Denmark DKr. (3.00 Germany DM -3.00 G-eece Dra 680 Holhnd DFI. -2.50 Italy 16500 1Rí2.97 Spain Pts. 700.00 Singapore SS -1.25 + WIRELESS WORLD USA 55.95

APRIL.1991 £1.95

TECHNOLOGY Getting into asic

''2), AUDIO DESIGN 0 / '1 4.£ Inside ' ©Q professional i1,17111y mixers r;;i1+F t,w

-r-ao' SCIENCE ^--`Í' .. Computers. in archaeology

,.,., . e .. .

PC ENGINEERING. Virtual instruments reviewed

Real-time PC operating systems 04

9 77095 9 833004 HIGH TECHNOLOGY DATA ACQUISITION BOARDS FOR AEROSPACE, ATE, R and D, ,.. a F ` f I / a ro"5-i.5. MEASUREMENT AND TEST 9, ,

NEW MODEL PC74 E,: DATA ACQUISITION BOARD 90 --- l t; ,-vr 1 sii5 T/r.r./331:11).- 1=.,:: DT 2811 . COMPATIBLE '' . ' . - ,;,r ti` _d k... r w : ~cs -o L1A11 o`e.;".M ` t`. o 1° -

,d'iép The Status data acquisition program which is supplied /51 with analog input boards .: 111, provides data acquisition at ,,.;!. ; AZS // maximum board throughput and features a graphic interface, pulldown menus and context sensitive help, Status has We market high performance advanced data processing features multifunction data acquisition such as FFT (Fast Fourier boards for laboratory test, Transforms) and Chirp Z measurement and control transforms, cursor read-out of applications. The multi -channel voltage and time, zoom and pan analog input may be used for signal operations and access to the boards analysis, data logging, sensor and analog output and digital I/O lines. transducer interfacing and voltage All screen displays can be plotted. measurement. Maths co -processors supported. r Analog out Speed Bits Single -ended Differential DMA Digital I/O Programmable 12 hit 8 -bit 16 -bit stain PC -30 25KHz 12 16 i/ps --- 2 2 - NO 24 lines _ No PC -30B 30KHz 12 16 i/p --- 2 2 - YES 24 lines No PC -30C 100KHz 12 16 i/ps --- 2 2 - YES 24 lines r No PC -30D 200KHz 12 16 i/ps --- 2 2 - YES 24 lines No * PC-30DS 200KHz 12 16 i/ps --- 2 2 - YES 24 lines No **PC-30DS/4 200KHz 12 16 i/ps --- 2 2 - YES 3-4 lines No PC-30PGL 200KHz 12 16 i/ps 8 i/ps 2 2 - YES 24 lines 1. 111, 100 1000 PC-301'G II 200KHz 12 16 i/ps 8 i/ps 2 2 - ES 24 lines -1, 2, 4, 8 PC -26 25KHz 12 16 i/p_. ------NO No No

PC -7411A 30KHz 12 16 i/ps 8 i/ps 1 2 - - NO 16 lines 1, 2, 4, 8 PC-74LA 30KHz 12 16 i/ps 8 i/ps 2 - - NO 16 lines -L.10, 100, 500 PC -7411C 80KHz 12 16 i/ps 8 i/ps 2 - - YES 16 lines 1, 2, 4, 8 PC-74LC 80KHz 12 16 i/ps 8 i/ps 2 - -. YES 16 lines 1, 10, 100 500 PC -32/H 2,5KHz 16 16 i/ps 8 i/ps - - I NO No 1, 2, 4, 8 PC -32/L _ 2 5KHz 16 16 i/ps 8 i/ps - - I NO No I , 10, 100, 500 PC -33/I I 2,5KHz 16 16 i/ps 8 i/ps - - - NO No 1. 2, 4, 8 PC -33/L 2,5KHz 16 16 i/ps 8 i/ps - - - NO No 1, 10, 100, 500 PC -34 ------I NO No --- PC-66 ------12 - - NO PC -66A ------8 - - NO No --- .. * Has 16 simultaneously sampled inputs ** Has 4 simultaneously sampled inputs

TEN DEXTER AVENUE WATERTOWN, MA USA 50 High SI CP Edgware 02172-4107 Middlesex TEL: 617-924-1155 HA8 7EP Citadel FAX: 617-924-1441 England United FlErhcnic /ncttc;rries Telephone: 081-951-1848 Products Ltd CONTENTS FEATURES

INSIDE MIXERS 280 ON THE RIGHT TRACK 311 A top -end mixing console should represents the highest Yachtsmen are increasingly looking to GPS for form of audio design. Soundcraft's chief designer Doug guidance. How have the manufacturers responded? Self describes the technology of acoustic excellence. CHIPPING AT THE PAST 286 .\ Archaeology is ripe for automation. A typical dig measurements required \ involves thousands of positional h . to produce a 3-1) image of the site. Archaeologist s''-_ { Helen Geake and technology writer Elisabeth Geake bring past and present together. N

THE SILICON TRAIL 791 IC design can be implemented in silicon in a variety of ways. Nigel Howell explains the pros and cons of different approaches.

0S9000: REALTIME PC 795 Lack of a real-time OS for the PC has held back r Q industrial application. but l\licroware's Stephen i4- ..:...-_. ;is.. _ \1ontgomery says OS -9(100 will change all that. INTERFACING WITH C 320 PC REVIEW - MAXSIM 300 Howard Hutchings continues his definitive series on Maxsim is designed to model and analyse the the use of the C programming language by electronics performance of systems in frequency and time domains. engineers. John Anderson tries it out and explains his reservations AUTOMOTIVE AUTOMATION 336 PC REVIEW - BLUE CHIP DMM 304 The car makers have always been able to produce a Blue Chip Technology's intelligent DM\I is one of the product which could move as fast as their marketing new breed of virtual instruments for the PC, offering departments wanted. Electronics has given the motor voltage and current measurement. chart recording and Indust y something else to sell cat. By Tom Woodford. data logging. FM RADIO: A BETTER TUNE 345 PC REVIEW - PCL860 4.5 DVM 307 John Linsley Ilood continues his short series on FM

I -low well does the Fairchild 4.5 digit voltmeter board receiver design. looking at the way in which component stand up to scrutiny:' Allen Brown investigates. development has influenced technique.

REGULARS

COMMENT 267 dead duck grouse, testing tintes. diode nonsense. and Researching priorities unsound models.

RESEARCH NOTES 269 NEW PRODUCT CLASSIFIED 351

I lalf-baked universes. supercool scientists, better CCDs New products at -a -glance. and mega -mega atomic memories. RF CONNECTIONS 356 UPDATE 275 Exploiting the spectrum above 30GHz. mobile comms Teraflops for euro -supercomputers. rise strategy. confusion and working in the rain. soaking up the sun. 20.000 lasers on a chip. Plus a special report from the ISSCC. San Francisco.

APPLICATIONS 315 In next month's issue. As :et only the military Adding a range switch to a l)PM. function generator superpower; have made use cf Over-The-Hori7on- and turning off mosfets. Radar. The Australians are ncw planning to spend

nearly £400 million on an I IF radar system to protect CIRCUIT IDEAS 331 their sparsely populated rorihen coastlines. Digital phase meter. fuse blown indicator. composite The impetus behind the radiating monster is feedback :mplifier. battery life extender. precision civilian: the Australian governiient hopes to use the pulse width generator and high frequency switch. radar to detect illegal aircraft running drugs into the Northern Territories. H. wever, the massive pulsed LETTERS 3.40 HF power.spells bad news for communications Back to the future. social worries. supporting Unix. systems operating around 14MHz.

April 1991 ELECTRONICS \\'ORLD+\\'IRELESS WORLD 265 Sg rfle programmers are more powerful th others...... P

i

The CP1128 is qualified by all major device manufacturers - like AMD, Lattice, Samsung and TI. This means'that you can feel secure that you'll be programming exactly as the manufacturer specifies and you won't get field failures from poorly programmed devices. It. programs over 2000 different devices - GALs, PALs, EPROMs, ERASICs, EPLDs Nothing's worse than finding that your shiny new programmer want work with the device you need. We've added 'more than 600 devices during the last 4 months and we're working hard to keep up with the manufacturers. We offer an absolutely free, lifetime, software update service. When you use a BP programmer you get on demand support for new devices as we produce the software. The new software costs you nothing and we'll continue to support you as long as you own the programmer. Last, but not least, the CP1128 costs less than £1000. It costs £985 and has a years guarantee. Like we've always said - power, reliability and value for móney. MUTEK (MSS) Ltd. Frome Road, Bradford on Avon, Wilts. BA18 1LE 02216 6801/6808 or fax -5083 CIRCLE NO. 126 ON REPLY CARD COMMENT

CONSULTING EDITOR Philip Darrington Researching priorities 081-6618632 The Science and Engineering Research directly in ceramic exhaust valves for EDITOR Council has recently been involved in vehicle engines, uniquely efficient Frank Ogden the yearly flurry of indignation over industrial production. hegemony in 081-661 3128 underfunding allegations. In essence, advanced semiconductor supplies. SERC is faced with effective budget cuts One could argue that any of these DEPUTY EDITOR of up to £30 million which temporarily achievements is more worthy than the Jonathan Campbell placed the Daresbury Nuclear Structure detecting of 9 neutrino, the analysis of 081-6618638 Facility under threat of closure. The radiation from a black hole or the Dareshury NSF provides a synchrotron knowledge that things aren't quite what DESIGN & PRODUCTION source for UK particle physicists. they seem at the speed of light. Alan Kerr Ramifications of the argument include Neither can it be taken for granted that an alleged overcommitment by SERC to big science generates useful spin-offs with EDITORIAL ADMINISTRATION international big science projects, cost effectiveness. Although the Apollo Lindsey Gardner principally CERN at Geneva, which have progran me resulted in non-stick frying 081-6613614 experienced greater cost inflation than pans. it might he said that a down -to -Earth SERC's UK commitments. Because related space programme costing the same ADVERTISEMENT MANAGER Britain's percentage contribution is fixed amount of money could have resulted in Jan Thorpe by international agreement, the effect has earth resources technology plus non-stick 081-6613130 been to reduce differentially the funds frying pans. In short, the sponsoring of available for UK work. competent research into the tangible DISPLAY SALES MANAGER It seems sensible to bring into question problems of industry' seems more likely to Shona Finnie the entire system of UK science funding. produce useful spin-offs than indulgence 081-661 8640 After all, we would expect other areas of in pure science. the economy to he subject to performance What is the Western preoccupation with ADVERTISING ADMINISTRATION tests. Why not science? The fundamental high science really about? While few of Karen Baines question is this: is pure science a luxury or us would disagree that the reciprocity 081-661 8469 a necessity? between the light-years of cosmology and The Japanese funded their economic the fenttoseconds of subatomic particle ADVERTISING PRODUCTION miracle by investment in applied science. physics is truly a source of wonder. it Una Russ Their electronics industry took over the shouldn't he an aspect of ersatz religion 081-661 8649 world by concentrating on research into which, one suspects. big science has the humdrum. It didn't question string become. PUBLISHER theories, it couldn't care less about the The size of a science research budget Susan Downey precision of the statement "e=mc ". It should he commensurate with the 081-66I 8452 concentrated on materials research, generally perceived value of the aim. artificial intelligence on the production Atter all, the really useful things in life FACSIMILE line, the movement of atoms around a don't require obscure explanations of their 081-661 8956 semiconductor lattice. This resulted worth. Frank Ogden

Electronics World + Wireless World

We are currently undertaking a appreciation using the scale 1 (low) to 5 programme of reader research. Please on the post-paid reader reply card help us to give you the magazine that located between pages 328/329 of this you would wish by scoring individual issue. The item key can he found at the editorial items. Please mark your end of each article F O

Electronics World r Wireless World is published monthly. By post, current issue £.2.25, back issues (if available) -£-2.50. 4-2 BUSINESSFSS Orders, payments and general correspondence to 1333, Electronics World Wireless World, Quadrant House, The PUBLISHING Quadrant, Sutton, Surrey SM2 5AS. Telex:892984 REED BP G Cheques should be made payable to Reed Business I` SI Publishing Group. GROUP Newstrade: Quadrant Publishing Services, 081-661-3240 Subscriptions: Quadrant Subscription Services, Oakfield House, Perrymount Ftoad, Haywards Heath, Sussex RH16 3DH. Telephone 0444 441212. Please notify a change of address. Subscription rates 1 year (normal rate) -1.30 UK and 1.35 outside UK. USA: $116.00 airmail. Reed Business Publishing (USA), Subscriptions office, 205 E. 42nd Street, NY 10117. Overseas advertising agents: France and Belgium: Pierre Mussard, 18-20 Place de la Madeleine,Paris 75008. United States of America: Jay Feinman, Reed Business Publishing Ltd, 205 E. 42nd Street, NY 10117.Telephone (212) 867-2080. Telex 23827. USA mailing agents: Mercury Airfreight International Ltd Inc, 10(b) Englehard Ave, Avenel NJ 07001.2nd class postage paid at Rahway NJ Postmaster. Send address changes to above. ©Reed Business Publishing Ltd 1989 ISSN 02663244

April 1991 ELECTRONICS WORLD+WIRELESS WORLD 267 HF-235 A. landmark in HF monitoring

610011 ,.. ` HF-235 . .2 i,4133 y. t

The HF-235 is a highly cost effective solution to * 30kHz-30MHz the need for a synthesised HF receiver for the * USB/LSB/CW/AM/FM/AM sync professional user. The HF-235 can be used as a * All IF filters fitted as standard Conventional tuning knob keypad stand-alone general purpose monitor or in or entry * 30 memories and 2 VFOs multiple unit installations where diversity or 600 ohm line driving multi -channel is monitoring required. * Optional. RS -232 interface for remote control LOWE ELECTRONICS LTD, Chesterfield Road, Matlock, Derbyshire DE4 5LE Telephone: (0629) 580800 Fax: (0629) 580020

CIRCLE NO. 127 ON REPLY CARD Toroidal - - PC WAVEFORM GENERATOR Transformers ' As manufacturers we are able to offer a range it - of quality toroidal and laminated transformers I' l at highly competitive prices. Toroidal Price List FEATURES Quantity prices Exclude VAT & carriage APPLICATIONS * Powerful complex Quantity Price Excluding VAT & Carriage * Arbitrary waveform VA Mall Order 2 10 25- 10 100 i. waveform generator simulator 15 12.16 8.51 6.89 5.17 5.02 4.87 * Four analogue outputs 30 13.37 9.36 7.35 5.68 5.51 5.35 * Low cost ATE 50 14.86 10.40 8.17 6.32 6.13 5.94 * Five TTL outputs 60 15.02 * Process control 10.51 8.26 6.38 6.20 6.01 * External trigger input 80 14.98 10.50 8.25 6.38 6.19 6.00 * Robotics 100 17.58 12.29 9.88 7.48 7.24 7.02 * Up to 6MHz clock rate 120 17.95 12.57 9.87 7.63 7.41 7.18 150 21.65 15.16 11.81 9.20 8.93 8.66 * Comprehensive FREE DEMO DISK 160 19.86 13.90 10.92 8.44 8.19 7.94 225 25.09 17.56 13.80 10.66 10.35 10.04 software included ON REQUEST 300 28.60 20.02 15.73 12.16 11.80 11.44 400 38.49 26.94 21.17 16.36 15.68 15.40 * Standard waveform 500 42.07 29.45 23.14 17.88 17.35 16.83 We 625 44.24 34.47 27.08 20.93 19.31 18.70 library also supply a full range 750 48.66 38.86 28.98 22.38 21.72 21.06 * User definable of DIY parts for PCs and 1000 65.67 45.97 36.12 27.91 27.09 26.27 1200 68.71 48.10 37.78 29.20 28.34 27.48 waveform library clones. Call us for more 1500 87.58 61.36 48.17 37.22 36.13 35.03 2000 114.45 80.11 62.95 48.64 47.21 45.78 * Full graphical editor information or a free 2500 135.87 95.11 74.73 57.71 58.04 54.35 * Time delay, continuous catalogue. These prices are for single primary with two equal secondaries with 8 coley coded fly leads. & single shot Each transformer Is supplied with a mounting kit. consisting of one steel washer, two neoprene Designed and pads, end a nut and bolt. * Example microcode Please do not hesitate to telephone or write with your particular requirements. manufactured by us in the Available from stock in the following voltages: 6-0-6, 9-0-9, 12-0-12, 15-0.15, and assembler also 18-0-18, 22-0-22, 25-0-25, 30-0-30, 35-0-35, 40-0-40, 45-0-45, 50-0-50, 110, 220, 240. UK. Full technical support Primary volt. included for OEM 240 applications. from the designers! AIR . Unit 14A, Sunrise Business Park, BLACKMORE Blandford Forum, %; LINK ELECTRONICS LIMITED Dorset. DT1 1 8ST. Air Link Transformers Telephone (0258) 451347 Unit 6, The Maltings, Station Road, Sawbridgeworth, Herts. Fax (0258) 456046 Tel: 0279 724425 Fax: 0279 726379

CIRCLE NO. 128 ON REPLY CARD CIRCLE NO. 129 ON REPLY LARD

26t ELECTRONICS \\ ORLD+WIRELESS WORLD April 1991 RESEARCH NOTES

Is lumpy universe theory half-baked ? The scale of the Universe is so mind -bog- very smooth. homogenous beginning - Cold dark matter seems to explain so glingly big that it's scarcely surprising we know it was smooth because echoes of well virtually every feature of the universe when cosmologists have to tinker around Big Bang can still be detected in the form that it is often taken for granted. Small with theories to accommodate the vast of an isotropic 3K microwave background wonder, then. that the latest study ques- wealth of information being beamed down radiation. tioning its validity has caused quite a stir. from the various orbiting observatories. CDM. consisting of slow moving Using data from the infra red astronomy But to judge from a recent paper (Nature ghostly particles, has never been detected. satelli:e Iras. the cosmologists have vol. 349, no 6304) by British and hut if it were to make up about 90% of the mapped the locations of 2000 individual Canadian researchers. some of theories Universe. it could have drawn matter galaxies and showed that. on a scale of are so seriously adrift that it's virtually together into the lumpy structure we hundreds of millions of light years. the hack to the drawing board. observe today. The presence of CDM Universe is just much too lumpy. Clusters What is in particular trouble is the would also satisfy other cosmological of galaxies are lumped together into huge notion of cold dark matter (CDM). a con- problems for which a large amount of blobs and filaments with relatively empty cept put forward to explain the lumpy dis- matter is a prerequisite. voids in between. tribution of matter in the universe. CDM. {lot or faster moving particles might Professor Michael Rowan -Robinson of or something like it, was introduced supply sonic of the "missing" mass, but Queen \lacy and Westfield Colleges in because cosmologists could not otherwise they don't stay in one place for long London. one of the study's authors. says understand how galaxies managed to form enough to explain the clustering of the that CDM theory can explain mass distri- so quickly from what was originally a galaxies. bution t.p to the size of the Virgo cluster

that is true then exploration teams could Supercool scientists take the heat be missing a lot of good deposits. Of course that possibility is pure spec- out of fast chips ulation, but there are several more down- to-earth applications for geometric super- Chill a container of water below 0°C and are interesting because they are not, as cooled fluids. One that is particularly it will gradually freeze into a block of might be expected, tiny glass test -tubes, exciting is the prospect of their use for ice. But use a very pure liquid - and but microscopic pores in blocks of spe- cooling high speed chips. take great care - and the temperature cial high-porosity glass. As things stand, the ability to dissipate can be lowered below its normal freezing Size of the pores is controlled during heat is probably the biggest barrier to point without any ice crystals appearing. the manufacturing process; they are then increasing switching speed and/or pro- Researchers are now wondering if this filled with a variety of experimental flu- cessing density. As chip structures shrink phenomenon could be harnessed in cool- ids, including liquid oxygen, liquid nitro- and processing capacities rise. there is an ing superfast and high density chips. gen. alcohol, carbon disulphide and ever-increasing risk of overheating. "Supercooled" fluids are highly unsta- nitrobenzene. If molecule -sized channels were to be ble and will freeze suddenly if disturbed But depressed freezing points are not machined into the structure of a chip, by any noise or movement. But Dr David the only peculiarities of geometrically supercooled fluids could be pumped Awschalom of IBM's Thomas 1 Watson supercooled fluids. Using a glass block through them to remove the surplus heat. Research Centre, Yorktown Heights NY containing tens of thousands of pores, It is a process that should be aided not has shown that. in a container only a few Awschalom has discovered some unusu- only by the lower temperature of the flu- tens of molecules wide, many liquids can al acoustic properties. ids, but by another strange physical prop- be supercooled to well below their nor- Ultrasonic techniques to measure the erty that occurs at very low temperatures, mal freezing points and can spend weeks velocity and attenuation of sound waves superfluidity. Superfluidity - the loss of in this remarkably stable liquid state. show that although they are physically viscosity - is also affected by the size In one series of experiments Dr liquid, geometric supercooled fluids can of the container in which a fluid is con- Awschalom and his team found that liq- have similar acoustic behaviour to solids; fined, a subject currently under investi- uids trapped in tiny containers could he sound waves travel faster and experience gation. chilled to 40% below their normal less damping. This discovery could he of David Awschalom believes that all Kelvin freezing points without solidify- crucial importance for oil exploration these fascinating properties of super- ing. As the size of the container where prospectors use sound waves to cooled liquids could eventually have decreased, the freezing point progres- try to distinguish pockets of oil from widespread applications. not just in com- sively dropped, an effect Awschalom rock. Awschalom thinks that supercooled puters and oil prospecting, but in cooling calls "geometric supercooling". oil in porous rock in arctic regions could and lubricating tiny gears and motors The containers used in the experiments well be masquerading as solid rock. If smaller than the eye can see.

April 1991 El .ECTRON ICS WORLD+WIREI.ESS WORLD 269 RESEARCH NOTES

of galaxies. But cold dark matter cannot cept invented by Einstein in 1917 and Weijtens' study, part of a project in the be reconciled with the structure of super - later disowned. Einstein's cosmological Esprit programme, has shown that indium clusters. constant implies the existence of an extra tin oxide (ITO) can be used successfully He admits that most cosmologists prob- force to balance that of gravity, thus pre- as an electrode material to replace polysil- ably do not now know in which direction venting the inward collapse of the icon. to go in terms of new theories. Universe. ITO, one of the few available alterna- Rowan -Robinson himself believes that But if, like me, you get the impression tives, is both conductive and transparent, it might be possible to create a cosmologi- that this is all a bit hard to accept, you'll its only problem being that it tends to cal model involving both cold dark matter appreciate an editorial in the same edition cause troublesome crystal defects in the and hot dark matter, the hot material con- of Natre. It observes that "if cosmolo- SiOx oxide layer of the sensor. Defects sisting of particles like neutrinos travel- gists are forced to start throwing around result not only in a loss of sensitivity but ling at near to the speed of light. several kinds of dark matter along with a also in visible faults. Another possibility that would save the cosmological constant, scepticism is Weijtens found that one of the causes of CDh1 theory would he to resurrect a con- hound to arise". Really? the damage to the crystal lattice is the charging of the non -conducting SiOx layer by the very process used to deposit Improved electrodes will the ITO. mean Production better image for CCDs First step in producing ITO electrodes Solid state image sensors such as the well - By applying appropriate voltage pulses consists of a magnetron sputter arrange- established CCDs have ousted thermionic the packages of electrons are sampled and ment in which indium and tin atoms are and vacuum devices in a wide variety of converted into an output, and the amount forced out of a cathode by ion bombard- applications. But just as vidicons and the of charge under each electrode is a mea- ment at low pressure in an atmosphere of lead oxide camera tubes underwent con- sure of the light absorbed. argon and oxygen. tinuous development and improvement. The indium and tin atoms combine with the same is now proving true of solid state the oxygen to form ITO, deposited on an image sensors, particularly in the search ITO replaces polysilicon oxidised silicon wafer, and thereafter the for new electrode materials. The present generation of image sensors electrode structure is etched using a pho- CCDs can be found everywhere: from uses polycrystalline silicon as the elec- toresist. By applying a very thin, almost the home camcorder to the biggest astro- trode material because it is easy to control transparent, conductive layer of polycrys- nomical telescopes in the world. In princi- and process. Only disadvantage is that it talline silicon prior to the ITO, Weijtens ple, the chips all consist of a series of nar- absorbs light which in turn reduces the found that the charging of the SiOx layer row light -transmitting electrodes applied sensitivity of the sensor. But that may is prevented. to oxidised wafers of silicon. soon become a thing of the past, thanks to Another advantage of this extra layer is If light falls on the electrodes, electrons research by Christ Weijtens at the Philips that the SiOx layer is clean and well are released into the underlying silicon. Research Laboratories in Eindhoven. defined. Using a final brief heat treatment at I !If 950°C with subsequent heat treatment at a lower temperature, any remaining crystal defects are reduced considerably.This y, improves the light absorption and also the ,e electrical properties of the chip. Although development is still at the laboratory stage, it promises the possibili- ty of a new generation of cheaper and : .* considerably better image sensors.

1 ( ,.m ; i _ . l . A!....R! y r M slndium and tin atoms, forced out of a rt4strttt sibtli*iy%L, *,4tta.sira+> .. cathode by ion bombardment, combine #, 4clre#iFR¢;ASgic'¡Eftlws+1{41'!+*x+:+x,43tE }ilXx.aa with oxygen to form ITO, deposited on .>sr .t yx++« S r >' +'` sI,tss 4 s ?., ,. an oxidised silicon wafer. t ! ` Electrode . . ' ' structure is etched using a photoresist. A thin conductive layer of polycrystalline silicon prevents charging of the SiOx layer. l S'11r w Iv, ta ík it L R Mn Xi rr 9l xk -r.l í .: f r u a a et r ut.E a»w lx r ma 1, r' LI Al. 31. tlw.,e i a itIL a

270 ELECTRONICS WORLD + WIRELESSWORLD April 1991 L _RJET1 HIGH PERFORMANCE COLOUR 1NK'.JET PRINTER (compatible with IBM pc, BBCImicro, Nimbus etc.) * PRINTS ALL'64 SCREEN COLOURS FROM CGA :AND EGA USING

OPTIONAL INTEGREX'SOFTWARE . * EMULATES OTHER PRINTERS (IBM3952, PJ1080A and QUADJET)

* OVERHEAD TRANSPARENCY PRINTING . * 8G+ 132 COLUMN OPERATION, A4 WIDTH TEXTILE * --UP TO11280 DCTS/LINE ADDRESSABLE PRINTING * FULL VIDEOTEX CAPABILITY. ; INK CARTRIDGES * OPTIONAL BUFFERED RS232. (INTERNAL) - NOW AVAILABLE * HIGHLYVERSATILE

ULTRA LIST PRICE LOW £636 + VAT NOISE

COLOLIRJET 132

EDUCATIONAL DISCOUNTS AVAILABLE -

INTEGREX LTD CHURCH GRES_EY, BURTON ONTRENT STAFFS DE11 9PT PUB LC SE :TOR CUSTOMERS Tel (0283) 551551 iW36.1T FOR SPECIAL PRICING CALL oB Fax (0283) 550325 HMSO I99I Telex 341727 INTEGX CIRCLE NO. 1300N REPLY CARD SECOND USER INSTRUMENTS PRODUCT PRICES FROM PRODUCT PRICES FROM PRODUCT PRICES FROM

AVO FT6/12 AC/DC Breakdown, £950 FIREBERD 6000 Data Error £3750 MARCONI 2955/2960 Multi - £3000 Leakage and Ionisation Analyser designed to analyse, standard Radio Test System. Tester suitable for flash evaluate and troubleshoot (Various software options testing and non-destructive digital communications systems available i.e. TACS, NMT, testing. and equipment. Band III and AMPS). ADVANCE-BRYANS 60020 X-Y/t £650 FIREBERD 40392 RS232N.24/M1L- £550 MEGGER PAT2 Portable Appliance £195 Recorder. 188 Asynchronous interface. Tester. BBC GOERZ Servogor 120 £450 FIREBERD 40236 RS232 Synchronous £290 PHILIPS 5193 50MHz Programmable £1550 2 Channel Chart Recorder. interface. Synthesised Function Generator. BRUEL 8 KJAER 2221 Sound £1700 FIREBERD 40200 RS449N.II/ £475 POWERSENSE Single Phase Mains £850 Level Meter. X.21 DTE/DCE interface. Analyser, with built-in printer. CEL 213 Random Noise £310 FIREBERD 40202 V.35 DTE/DCE £475 PRISM 5042 Power Supply Unit. £1200 Generator (suitable for interface. Voltage range 0-30V, current White Noise Generation). limit 10-2200mA. FIREBERD 30608 64kbps G.703 £795 CIL PCI 6380 I/O Units for £150 Co/contra directional interface. RACAL 1991 Universal Counter £490 HP-IB. suitable for direct measurement FIREBERD 40380 2.048Mbps G.703 £475 up to 160MHz. CIL Multi-monitor, 10 Channel £180 Unstructured interface. Voltage Acquisition Unit. For RACAL 1992 Universal Counter FIREBERD 30609 2.048 Mbps G.704 £750 £995 millivolt, thermocouple and As 1991 with input Structured interface for Framing/ but C with strain inputs. Includes HP-IB frequency range 40MHz to 1.3GHz. interface. CRC -4 testing. SCHAFFNER NSG200E Main- FIREBERD 30447 T2 interface. £895 System £950 CHESSELL 306 6 Channel £450 frame. Recorder. FIREBERD 6000 Jitter Option 6007/8. £2300 SCHAFFNER NSG203A Plug-in. £1650 CHESSELL 4001 Multi -function £1750 FLUKE Type 37 Digital Multimeter. £240 SCHAFFNER NSG204A Plug-in. £1295 Data Logger/Chart Recorder. FLUKE 8010A 3.5 Digit LCD Bench/ £125 (Up to 30 inputs). Portable Multimeter. SCHAFFNER NSG222A Plug-in. £1350 CHESSELL RTD Board with SCHAFFNER NSG223A Plug-in. SIMM £225 FLUKE 8012A 3.5 Digit True r.m.s. £175 £1695 Module for 4001. LCD Bench/Portable Multimeter. SCHAFFNER NSG224A Plug-in. £1800 CHESSELL DC INPUT Board with £225 FLUKE 9010A Microsystem Trouble £1295 SCHAFFNER NSG225 Plug-in. £1650 SIMM Module for 4001. for Shooter. Suitable locating SIEMENS C1732 Multireg faults microprocessor fast Multi- £1875 CLARE A203C/J Flash Tester. £325 on based channel Recorder, with facility of circuit boards. COMARK 6600 Autoscan Thermo- £480 up to 32 channels. meter providing GOULD 1421 20MHz Digital Storage £375 automatic SIEMENS DC Current Module. £75 scanning of up to 10 Oscilloscope. SIEMENS DC Voltage Module. £75 thermocouple inputs. GOULD 1425 20MHz Digital Storage £650 COMARK 4600 Printer for Comark £180 Oscilloscope. SIEMENS DC Universal Module. £85 6600 Autoscan Thermometer. GOULD Type 135 Waveform Processor £125 SIEMENS C1013 Recorder £1750 DATA 1/OModel 1010 Chip Dupli- £2800 Keypad. STAG SE15 Eraser. £50 cator mainframe. 400 GOULD 100Ms/sec Dual Channel £1210 STAG PP39 Universal MOS EPROM £375 DIGILOG 300 Protocol Analyser £1800 Digital Storage Oscilloscope. Programmer (Includes RS232 Inter- for data communications testing HEWLETT PACKARD 8112A Pulse £2500 face). up to 19.2kbps. Generator. STAG PP40 Ganged EPROM/EEPROM £325 DIGILOG 420 Protocol Analyser £4700 HEWLETT PACKARD 5385A Frequency £985 Copier. for data communications testing Counter. up to 72kbps. STAG PP41 Ganged EPROM/EEPROM £650 HEWLETT PACKARD 54100A 1GHz £3000 Copier (Includes RS232 Interface). DIGILOG 620 Protocol Analyser £7200 Digitising Oscilloscope. for data communications testing STAG PP42 Gang/set Copier (Includes £950 up to 128kbps. HEWLETT PACKARD 54001A 1GHz £325 RS232 Interface). Miniature Active Probe. DOWTY TRIO Multi-standard 1200, £250 STAG ZL30 PAL Programmer. £975 1200/75, and 300bps full duplex HEWLETT PACKARD 10269B Probe £200 STAG ZL30A PAL Programmer. £1295 modem; conforms to CCITT V.22. Interface Assembly for 1630G V.23, V.21 with Bell 212A, 202 Logic Analyser. STAG PPZ Universal Programmer £1800 mainframe. and 103 options. HEWLETT PACKARD 10300B Z80 £250 DRANETZ 808 Power Demand £2500 Microprocessor interface. STAG ZM2000 Universal PROM £950 Module for Stag PPZ. Analyser for monitoring, display HEWLETT PACKARD 10305B 8086 £600 and print out of V, I, PF. Microprocessor interface. STAG ZM2200 Logic Module for £1195 kW. kVA, kVAR demand. Stag PPZ. HEWLETT PACKARD 10311B 68000 £750 DRUCK DPI 600 I.S.2 Portable £350 Microprocessor interface. TEKTRONIX 2225A Dual Channel £350 Pressure Calibrator. 2 bar 50MHz Oscilloscope. Calibrator. HEWLETT PACKARD 4951B/001/106 £1765 Data Communications TEKTRONIX 2445B Four Channel £1500 DRUCK DPI 600 I.S.7 Portable £350 Protocol Analyser. 150MHz Oscilloscope. Pressure Calibrator. 7 bar Calibrator. HEWLETT PACKARD 4953A/001 £3500 THANDAR TG503 5MHz Pulse/ £195 Protocol Analyser, to include Function Generator. DUX DICE 8085 Microprocessor £850 expansion memory. In -Circuit Emulator. THANDAR T0315 15MHz Battery £175 HEWLETT PACKARD 4953A RS232 £500 Portable Oscilloscope. ELAN 5000 Editing Programmer £1725 Pod. for EPROMS/EEPROMS from 2716 THANDAR TS3022 Bench Power £350 to megabyte devices. HEWLETT PACKARD 4953A RS449 £500 Supply. 30 volts, 2 Amps. Pod. ELAN Universe 1000 Universal £850 TIME ELECTRONICS 2003 Voltage Calib- £225 Programmer. HEWLETT PACKARD 54501A 100 MHz £1485 rator. 4 Channel Digitising Oscillo- TIME 9000 Series Various. P.O.A. ELAN Stack Modules for Elan £300 scope. Universe 1000. TREND DT100 RS232/V.24 Data Communi- £325 HEWLETT PACKARD 3780A Pattern £6100 cations Test Set. ERO Memocal 81B Process £525 Generator/Error Detector. Calibrator and Transducer A comprehensive error measuring TREND DT105 RS232/V.24 Data Communi- C395 Simulator. set in one portable package. cations Test Set. FARNELL AP60/50 Autoranging £950 MARCONI 2019A RF Signal £2750 TRIO LAI910 GPIB Bus Analyser. £795 Bench Power Supply Generator with AM, FM and Analyser for IEEE -488 Bus. provides DC up to IKW. Output OM for testing in the frequency maximum. WAVETEK 191 20MHz Pulse/Function £850 60V, 50A range 80kHz to 1040MHz. Generator. FEEDBACK SFG606 Function Sweep £250 MARCONI 2022A RF Signal £2550 WAYNE 4210 Generator, frequency range KERR LCR Component Meter. £495 Generator offering frequency, For measurement L, R, 0.01Hz to 1MHz. of C. D, O, % amplitude and phase modulation deviation. FEEDBACK VP0602 Variable Phase £520 over frequency range 10kHz to WAYNE KERR 4250 LCR Component Meter. £650 Oscillator. 1000MHz . For measurement of L, C, R, D. O. %

FIREBERD 1500A Data Error £1500 MARCONI 2955 Radio Communications £3990 deviation . for Test Set. Analyser evaluating commu- WAYNE nications links and hardware KERR Capacitor Tweezers for £35 MARCONI 2955A Radio Communi- £4650 4250. performance. cations Test Set. WEIR 4000T Stabilised Twinpack Power £175 Supply Unit. Dual single output of 0-30V at 2A. Ring (0 763) 247251 r First Rental Limited PO. Box 19, Newark Close, York Way, Royston, Herts, SG8 5HH

r Fax: (0763) 242106 CIRCLE NO. 131 ON REPLY CARL) Computers and Peripherals also available. Prices quoted are for one-off quantity and exclude warranty. Prices quoted exclude carriage charges and All products sold are fully tested and callibrated to manufacturers specification, V.A.T and are subject to availability. and wil be eligible for manufacturers maintenance contract where appropriate. RESEARCH NOTES

Atomic power drives megamega memories

Last year IBM scientists Don Eigler and the tunnel diode) is critically dependent Last year's spectacular result came Erhard Schweizer achieved something of on the gap between a pair of charged con- about when Eigler and Erhard developed a publicity scoop by printing the company ductors: increase the gap and fewer elec- the STM beyond that of a mere passive, logo with individual xenon atoms on a trons can traverse it. If one of the conduc- diagnostic tool. Using higher voltages on nickel substrate. Now Hitachi scientists tors is placed in a feedback loop so that the probe and cooling their samples to have now taken the technology another the electron flow remains constant, then it near absolute zero they managed to nudge stage forward by detaching individual will hover at a specified distance from the 35 xenon atoms into specified locations in atoms from what was previously a uni- other conductor. the nickel lattice. form flat surface. For the electronics Hitachi scientists have now taken STM industry the eventual result could be technology another stage forward by memories a million times denser than cur- Microscopic tracking doing almost the reverse, detaching indi- rent devices. In the case of a practical STM the mov- vidual atoms from the uniform flat sur- It was perhaps appropriate for IBM to able conductor is made in the form of a face. be making the running in the original very fine needle that floats over the fixed What's more, they've proved they can work, since its scientists had previously specimen. And because it is forced to do it at room temperature, a significant won a Nobel prize for inventing the maintain a precise spacing, the needle, achievement. enabling technology. Moving individual when moved sideways, will track the As with the IBM work the method atoms around and, even more surprising- microscopic hills and valleys of the speci- involved scanning the surface of the sub- ly, being able to produce an image of the men in a manner analogous :0 the stylus strate using a voltage and spacing to give result is an incredible feat considering that of a record player. The only difference is a clear picture of that surface, but without the smallest speck of visible dust may that the STM needle can track hills and changing it. The STM needle was then contain around 1016 atoms. valleys on the atomic scale without ever moved even closer - a mere 3 The secret lies in a device called the touching them. Angstroms - and given a pulse of a high- scanning tunnelling microscope (STM) er voltage. A tungsten probe floating over which has revolutionised our ability to "Peace '91 HCKL" written in molybde- a surface of molybdenum disulphide was study matter down to atomic dimensions. num disulphide by removing sulphur used in the experiment and when the sur- This tunnelling effect (also exploited in atoms. face was subsequently checked using the STM in its diagnostic, or picture -taking mode, it was found that each pulse had ,,W removed a single sulphur atom from the

i1;1 t ,+ 4 0 molybdenum disulphide. ,. _ + o Although further studies will be neces- í Ac?2' sary to understand the atom detachment mechanism, Ilitachi researchers believe a. that the atoms are removed by field evap- dip 9, oration. a phenomenon in which atoms fly ,. --Ala into the surrounding space when the inter- R a atomic binding energy is overcome by a ó- des 'IN as'r . . R , alb strong electric field. 11111 a. r Excising individual atoms with high Al> OS0 ¢ o - _ precision has the same practical goal as all 4rs4".r 101 Oa ó 1 manipulation: higher Qn #r2,,- t 411- . 493 research on atomic " density memories and atom -scale active . * a devices. In memory terms alone a Hitachi . spokesman suggests that STM technology ! ..- by a r storage capacity fac- * 40OP might improve t . * - tor of 106 compared to today's 4Mbit o *' ^ - drams. -i!' da al 0^ + a ., 161 II© " 41.w . 6i1p © Research Notes is written by John Wilson .w. .404 -"Malo 4.1 of the BBC World Service science unit. 5,. 4.+ T 41/1 o. _ s+ -.' 41 . .-..-41" .----fr 1 ! .y` l¡tV mid Editorial survey: use the infomation card to evaluate this article. Item A.

ELECTRONICS WORLD + WIRELESS WORLD April 1991 273 UNIRAicOSB / . .:.,..:: ' :,:::.....:::::: .

:

' . .. . :::,,,:,:, .,..::: ,::::: ".: ...... ,,,,,.,:,:,.. , ...... ,...... :....,

//GRou P FIRST FOR QUALITY AND SERVICE

SWEEP GENERATORS FUNCTION GENERATORS HP 8620C Sweeper Mainframe £ 1,395 HP 3200B 500MHz Oscillator £ 641 HP 86242D 9 GHz Plug in £ 750 HP 3325B Synthesizer/Level Meter £ 3,250 WAG 1081 £ 2,500 PHI PM5190 LFSynthesizer £ 1,500 GREAT LOGIC ANALYSERS PHI PM5193 Programmable Synthesizer £ 2,350 HP 1630G 65 Channel Logic Analyser £ 1,450 RF GENERATORS HP 1631D Logic Analyser/Digitising Scope £ 3,250 HP 86574 1GHz Synthesizer Signal Generator £ 5,250 HP 1650A Logic Analyser £ 2,500 MAR 20194 Signal Generator £ 3,250 HP 16500A Logic Analyser Mainframe £ 2,500 MAR 2022A Signal Generator £ 1,950 HP 16510A 80 Channel Card £ 1,250 MAR 2022C Signal Generator £ 2,500 HP 1651A Logic Analyser £ 1,950 DIGITAL MULTIMETERS TEK 1240 Logic Analyser £ 895 FLU JF73 Digital Multimeter (handheld) £ 60 SPECTRUM ANALYSERS FLU 8026B Digital Multimeter (handheld) £ 150 ANR MS610A .52GHzAnalyserGHzSpectrum £ 2,750 PROM PROGRAMMERS CAN T#E ADV TR4131 3.5 GHz Spectrum Analyser £ 4,650 STG PP39-1 Prom Programmer £ 400 HP 35660A Dual Channel Dynamic Signal Analyser £ 7,000 STG PP41-2 Gang Programmer £ 950 HP 3585A Spectrum Analyser 20Hz -40MHz £ 8,750 STG PPZ Prom Programmer £ 650 HP 3585B Spectrum Analyser £13,500 STG Zm2000 Module £ 350 HP 85904 10KHz -1.5GHz £ 4 850 STG Stratos PC EPROM Programmer £ 190 HP 35624 Dynamic Signal Analyser £10,950 EX-DEMO EQUIPMENT (AS NEW) MAR 2382 Spectrum Analyser 100Hz -400MHz £11,500 OUR : FG7 Colour Generator £ 600 RAC 9702 1GHz Spectrum Analyser £ 1,000 HAM 1005 100MHz Oscilloscope £ 600 TEKIP 2710 Spectrum Analyser £ 5,500 PHI PM3305-40 35MHz 4 Channel DSO £ 1,700 PROTOCOL ANALYSERS PHI PM5518TX Pattern Generator £ 1,650 "' ""' HP49518 Protocol Analyser £ 1,250 RAC 1995 200MHz Universal Counter £ 1,850 HP 4953A Protocol Analyser £ 2,750 TEK 2221 100MHzDSO £ 1.950 WE BUY TOP HP 49544 Protocol Analyser L. 8,000 TEK 22464 100MHz, 4 Channel +DVM £ 1,750 HP 4951C Protocol Analyser £ 2,500 THA TA2500 72 Channel Logic Analyser £ 1,500 OSCILLOSCOPES MISCELLANEOUS HP 54501A 100MHz Quad Channel Digitising Scope £ 1,950 DAT 1081 Multimeter QUALITY E. 2,950 HP 54502A 2 Channel Digitizing Scope 400 Msa/s £ 3,500 HP 437B Power Meter (sensors available) £ 1,275 HP 54503A 4 Channel Digitizing Scope 500 MHz BIW £ 3,250 HP 2225A Thinkjet Printer £ 150 TEST PHI PM3315 60MHz DSO £ 1,750 HP 8745A RF Network Analyser £ 2,000 PHI PM3320 Digital Oscilloscope £ 3,950 KON 520 6 Channel Chart Recorder £ 2,650 TEK 2230 100MHz DSO £ 2,100 MAR 2958 Cellular Radio Test System £ 4,950 EQUIPMENT TEK 2236 100MHz Dual Channel Oscilloscope £ 1,600 MAR 6960A Power Meter (sensors available) £ 850 TEK 2445 150MHz Oscilloscope £ 1,500 RAC ST14DS Tape Recorder £ 4,000 TEK 2445A 150MHz Quad Channel Oscilloscope £ 2,050 SCH NSG 200E Disturbance Mainframe LONDON OFFICE TEK 2445B 150MHz Oscilloscope £ 2,450 (plug ins available) £ 900 AND HEADQUARTERS 2465A TEK 350MHz Quad Channel Oscilloscope £ 2,950 TEK 1502B TDR Cable Tester £ 3,250 TEK 2465A IR Group -OPTIC 350MHz Oscilloscope £ 3,331 YEW 3057 2CH Recorder £ 450 TEK 7S 11 Plug In Sampler £ 666 YEW Dorcan House 3081 Hybrid Recorder £ 1,950 PULSE GENERATORS Meadfield Road TEK PG506 Pulse Generator £ 1,281 Langley Berks SL3 8AL All prices advertised are exclusive of carriage and VAT. All equipment sold subject to availability. period 12 months Telephone: Warranty on all equipment (except computers MDS -3 months). 0753 580000 For further information telephone 0753 580000

CIRCLE NO. 133 ON REPLY CARD

273 ELECTRONICS WORLD+WIRELESS \1 ORLD April 1991 UPDATE

1993 aim for Europe 20 000 lasers on an IC Scientists at IBM's Zurich Research Tflops supercomputer Laboratory have developed a technique to A group of European academics and com- designed to capture a different portion of build 20 000 lasers on a round semicon- puter engineers is close to completing a the solar spectrum. ductor 2 -in across. It is claimed to be the design for a supercomputer which can Multi -junction structures have already first time anyone has been able to mass- process lTeratlop/s (I x 1012 floating demonstrated impressive gains in stability produce and mass -test semi -conductor point operations/s). over earlier single -junction devices. lasers on a complete wafer. European Teratlop Initiative, which In the new process narrow trenches includes academics from Cern and the Risc strategy 0.005 -in deep are etched into the A1GaAs University of Edinburgh as well as com- Mips Computer Systems has unveiled its like Parsytec and Meiko, believes plans for the R4000 rise microprocessors. panies " it can build a working machine by 1993. The 64 -hit devices. when they eventually `a ? `'111 -.mss s t' use an -stage . .T. ` .71 :' This is despite a recent EC report which appear as silicon, will eight 1«.,r instructions as litF ,t found that Europe would have to invest pipeline to execute two code ,= r 0". about £750million each year to catch up every clock cycle. dt -M with the supercomputer technology lead The company has plenty to say about built by the US and Japan. the technical points of its device; its cache The working group has welcomed the page lock mode, addressable memory report's call for funding, especially for range and pipeline stage bypass circuitry developing a market for European -built among others. But the most interesting l " 1 ' supercomputers. But members feel that features are very much more basic. , i}14 the expertise needed to make the machine There will he two versions of the chip. t i`I and write software already exists. One is housed in a 450 pill grid array and ETI's machine will use about 50 000 the other in a 180 lead package. microprocessors all running in parallel. Something which will certainly be left semiconductor wafers to form laser mir- One of the engineers working on the off the smaller size is the dynamic real rors. Previously mirrors were formed indi- design said that the biggest problem world delay compensation circuitry. The vidually for each laser by cleaving the had would be finding a suitable micro. "To 450 pin device will have two connections semiconductor crystal, and the lasers can build a computer with 10 000 processors shorted together on the circuit board. to be individually tested. Now IBM you need to have very small nodes, with allowing the chip to measure and accom- fabricate and test thousands of lasers at less than 10 glue logic chips per node. modate variations in the signal delay once or. an uncut wafer. This would he very hard with the ¡Intel) between the chip die and the board. If a Shown above is a wafer with 5000 i860." he said. chip maker produces a "faster" package lasers. Enlarged pictures show an array of But he expected it to he more workable than another, the user won't have to six individual lasers and accompanying with the H1 version of the transputer. worry about the difference. photo diodes, and a single laser and photo diode

$6.5m chance to Chip ship: The space Industries street float zone furnace is used for high -temperature superconductor materials processing research in nticrogravity environment aboard soak up the sun the Nasa KC -135 parabolic aircraft. The industrialised Macintosh -based system is A three-year programme has been drawn controlled by National Instruments' LabView2. up by the Solar Energy Research Institute -v i (Seri) to develop large area, high efficien- . ! cy, multi -junction thin film solar electric generating modules that convert sunlight 11',1ü I - itr directly into energy. °4t Under the programme Solarex and Seri - , 7.9' t will share the $6.5million cost of develop- 4--- 1 i' " ' t: ? . fr.. modules demonstrating a . I ing advanced stable conversion efficiency of 12%. The : .>_.--- contract also targets development of a 1: " small area (1 cm2) device with a 14% con- version efficiency. solar Unlike typical single -junction . \ cells, multi -junction solar electric devices t; r ,- `s: are constructed of several solar cells -Co placed on top one another, each being of w- 1., ..

April 1991 ELECTRONICS WORLD + WIRELESS WORLD 275 LASERS - SCOPES - AVOS - SOLAR MOTORS - FLOPPY DRIVES - HEATERS - PRINTERS - FIELD TELEPHONES - MEGGERS - ETC ETC all at unrepeatable prices

4 COLOUR PRINTER PLOTTER Sharp IP16 made ref for use with their MZ800 but AMSTRAD 3.5 FLOPPY DRIVE Reference FD9 brand new and perfect, £45. adaptable to many other computers. Brand new and complete with pens, paper, ATARI 64XE COMPUTER at 65K this is quite powerful so suitable for home or leads, and instructions. £25 plus £5 insured delivery. business, unused and in perfect order but less PSU, only £19.50, Handbook £5 extra. AVO-METER Ex British Telecom this is a 19 range 20K o.p.v. top grade instrument, CAR SECURITY ALARM protect your car (or other valuables) with an ultra -sonic alarm, covers AC & DC voltages, current and resistance, very good condition, fully working complete transmitter receiver and piezo shrieker, cased new and ready to go once PP3 and complete with leads £9.50, leather carrying case £2 extra (batteries not included battery is fitted was £40, now yours for £10. but readily available). 9" CATHODE RAY TUBE Philips M24/306W, which is not only high 12 VOLT 1.9 AMP -HOUR rechargeable battery by lap YUASHA brand new, charged resolution but is also X Ray and implosion protected, regular price over £30, ready for use £6.50 each. Solar charger to house this and keep it ready £29.50. you can have them at £12 each and you will receive the deflection coils as well tubes.are guaranteed unused. EPSON FLOPPY DRIVES 7 models in stock, all double sided all brand new and with 80 Watt MAINS manual, model nos SMD2801H, SMD280H, SWD180B, these are 31/2' and SD540, TRANSFORMERS two available in good quality, both with normal SD521L, SD580L, these are 5'/"£49.50 any model. primaries and upright mounting, one is 20V 4A the other 40V 2A only £3 each or 10 for £27 carriage paid. 100 WATT MAINS TRANSFORMERS all normal primaries:- 20-0-20 volt 2'/2A 30volt 31/2A, 40 volt 21/2A and 50 volt 2A all upright mounting, all £4 each, good quantities PROJECT BOX size approx 8" x 4" x 41/2" metal, sprayed grey, louvred ends for in stock. ventilation otherwise undrilled made tor GPO so best quality, only £3 each or £10 tor £27. COLOUR MONITORS 12" high resolution in black metal case with mains p.s.u. built in, unused, but line rejects so will require servicing, hence offered at the very low price of 12V SOLENOID has good V2" pull or could push it modified, size approx l'/2" long by £69.00 plus £5 delivery. I" square, £1 each or 10 for E9. PHILIPS 9" HIGH RESOLUTION MONITOR black and white in metal frame for easy WATER VALVE 230V operated with hose connections, ideal for auto plant spray or mounting, new in brand still makers packing, offered at less than price of tube alone, would control air or gas into tanks etc, £1 each or 10 for £9. only £15 plus £5 delivery- good discount for quantities. 5V 2'/2A POWER SUPPLY UNIT 230V mains operated, mains filtered and DC voltage 16 CHARACTER 2 LINE DISPLAY screen size 85mm x 36mm, Alpha -numeric dot LCD regulated with mains on/oft switch and indicator, £6 each or 10 for £50. matrix module with integral micro processor made by Epson their ref 16027AR brand HANG UP PHONE won't clutter up your desk or workbench, current model, has £8 each, 10 for £70, 100 for £500. push button dialling, last number recall, internal alarm etc., Ex B.T. in good condition and INSULATION TESTER WITH MULTIMETER internally generates voltages which enable fully working ready to plug in. £5 you to read insulation directly in megohms. The multimeter has four ranges. AC/DC HIGH VOLTAGE CAPS it you use these ask for our 1-30 Kv Capacitor list, we have over volts, 3 ranges DC milliamps, 3 ranges resistance and 5 amp range. These '/e million in stock and might save you a lot of money. instruments are EX British Telecom, but in very good condition, tested and gntd. OK, TWIN 360K 5.25 INCH FLOPPY DISK DRIVE with power supply built into a professional probably cost at least £50 each, yours tor only £7.50 with leads, carrying case £2.00 white case complete with mains extra. lead. Connections are via a 37 pin 'D' socket, full connection details supplied. Brand new by famous Japanese maker £59.50. 110 WATT POWER SUPPLY ASTEC switch mode, 230V mains input; 38V at 21/2A & 5V ELECTRONIC BUMP & GO SPACESHIP sound and impact controlled responds to claps 3A outputs, encased and fitted on panel mounting plate with mains input socket and and shouts and reverses or diverts should it hit anything! Kit with really detailed on/off switch, made for use with computers or other top grade equipment. You can instructions, will make ideal present for budding young electrician. Should be able to have it at a fraction of its proper price. Brand new and guaranteed. Sample £12.00 assemble but you may have to help with the soldering of the components on the PCB. post paid - 3000 available & good discount to quantity buyers. Complete kit £8.95. BRUSHLESS D.C. 12V FAN tiny, only 60mm square, good air mover but causes no 500V BRIDGE MEGGER developed for G.P.O. technicians the Ohmeter is the interference £8.00. 18B modern equivalent o4 the bridge meggar. 9V battery operated it incorporates a 500V 2MW LASER Helium Neon by PHILIPS, full spec, £30, power supply for this in kit form generation for insulation testing and a null balance bridge for very accurate with case is £15.00, or in larger case to house tube as well £17.00. resistance measurement. On the front panel there is a 3"x 3" panel meter calibrated MAINS 230V FAN best make "PAPST" 41/2" square, metal blades £8.00. in megohms to inf. and a small scale to indicate balance showing the exact setting of the four BATTERY MOTORS 12 models in stock in large quantities ranging from tiny model controls in the variable arm of the resistance bridge. Ex B.T. in quite good condition with aircraft one at 25p each to'/3hp made to drive the famous Sinclair C5 car, you can data&tested. Yours for a fraction of original cost £45+£5 insured have this at £17.50. delivery. TRAVEL SOLAR MOTORS I'/2 -9V precision made to operate from low current off solar cells MECHANISM goes backwards and forwards, could be used to animate a display or position £1.50, solar generator to drive this £7.00, has provision for battery backup when sun a device, battery or p.s.0 operated, distance of travel 4" and speed is not shining! of travel depends on applied voltage 1'/2V very slow I2V max is quite fast. £5.00. COPPER BOARD for making you pcb 174 x 100mm x 2mm thick double sided and SOUND SWITCH has countless uses, one could be to control the above travel mech. brand new. 50p each, £40 per hundred. £350 per thousand. Signals of 10 Hz to 20kHz picked up by its electret mike and FET amplifier and further amplified to be able to control relay motor etc up to 1/2 amp. supplied ready to work AIR SPACED TRIMMER CAPS 2-20 pf ideal for precision tuning uht circuits 25p each, from 6V. Price only £2. IO for £2.IOU for £15. EXPERIMENTING WITH VALVES don't spend a fortune on a mains transformer we can 1Khz. TONE GENERATOR this is PP3 battery operated and has a 1Khz output that can supply one with standard mains input and secs. of 250-0-250V at 75 mA and 6.3V at be continuous or interrupted at a rate variable by a panel mounted control. Also on 3 A. price £5. the front panel are separate output sockets for monitor or headphones, and a battery 15Watt Bohm 8" SPEAKER & TWEETER condition indicator. Constructed on a pcb and front panel size approx 105x 50mm ex 3" made for a discontinued high quality music equipment but in as new condition £2 each. centre, give real hi.fi. and for only £4 pair. TIMES OSCILLOSCOPE 3018 developed for testing transmission lines, it makes and displays TEN IONISER using transformers and novel circuitry, our ioniser emits at least !en times as many ions as does kit pulse echoes to find shorts and breaks in cable networks, this uses a 3" CRT to any other on offer, nor do we know of a ready built model is as display the type of fault and a LCD to read out the distance from the fault. The that good, you don't need a tester to see if it is working just bring your instrument is powered by I2V of rechargeable nicads located in base, and it hand close to it and feel the stream of neg ions. It's a kit complete with case, nothing else to buy yours for generates 1.5kv internally. It is housed in a high impact plastic case size approx 91/2" £14.50. x 91/2" x 5". Ex British Telecom in very good condition and working order, £49.50 ULTRASONIC TRANSMITTER/RECEIVER with Piezo alarm, built into preformed case, is plus £5 insured delivery. triggered by movement disturbing reflected signal, intended for burglar alarm, car alarm has many FIELD TELEPHONES just right for building sites, rallies, horse shows etc, just join two etc. extras, time delay, auto reset, secret oft device etc. A £40 instrument by twin wire and you have two way calling and talking, and you can join into regular yours for £ 10. phone lines if you want to. Ex British Telecom in very good condition, powered by MOVEMENT ALARM goes off with slightest touch, ideal to protect car, cycle, doorway, batteries (not included) complete in shoulder slung carrying case. £12.50 each. window, stairway, etc. etc. Complete with pieta shrieker ready to use. Only £2 (PP3 battery MAINS ISOLATION TRANSFORMER stops you getting "to earth" shocks. 230V in and not supplied). 230V out. 150 watt upright mounting £7.50. STEREO HEADPHONE extra lightweight with plug £2 each or 10 pairs for £18. MINI MONO AMP on pcb size 4" x 2" with tront panel holding volume control and Prices include V.A.T. Send cheque/postal order or ring and quote credit card number. with spare hole for switch or tone control, output is 4 watt into 4 ohm speaker using Add £3 post and packing. Orders over £25 post free, unless postage quoted 12V or 1 watt into 8 ohm using 9V. Brand new and perfect only £1. each or 12 for separately. £10. M&B ELECTRICAL (WW) EVER LASTING BATTERIES well nearly, Lithiam, have a shelf life of over 5 years so are 12 Boundary ideal tor fire alarms and similar circuits which must always be ready but get little Road, Hove, Sussex BN3 4EH maintenance, bargain offer 4 x 3V Lithiam batteries for £I. Telephcne (0273) 430380 Fax (0273) 410142

CIRCLE NO. 132 ON REYI T CARD

276 ELECTRONICS 11 ORLI)+WIRELESS 11ORL1) April 1991 UPDATE

Portable products and wireless communi- cations are now the two big areas of elec- tronics activity for leading technologists, IT'S GOING TO BE A judging by the International Solid State Circuits Conference (ISSCC) held earlier this year. As a result, flat -panel displays, ultra - WIRELESS WORLD low power memory and technological options for personal wireless communica- tion are all hot issues for current R&D. Low temperature polysilicon processing Looking first at displays. no less an would have to be mastered. authority than IBM's Ti Watson Research Sharp's assessment is that whereas both Centre is saying that full -colour, flat - approaches are feasible. polysilicon seems panel, thin-film transistor (TFT) liquid - the hest solution for high resolution dis- crystal displays are the future for comput- plays, though Hitachi think that integrat- er and television viewers, replacing the ing driver and interface circuitry onto the bulky and power-hungry cathode ray tube. glass will be more effective in reducing IBM believes that 1991 will be the year in the number of chips and connections than which these panels will be manufactured the overall replacement of peripheral cir- in quantities of more than a million. cuits by polysilicon TFTs. A keynote speaker from Toshiba sup- Whether anioprphous silicon or polysil- ` ported that view. Perhaps it is no coinci- icon becomes the dominant technology. 4.9= dence that IBM and Toshiba have a joint drive requirements will differ from CRTs. 3s venture to manufacture large, colour CRTs are scanned and require a serial active -matrix LCDs. First factory comes analogue input; active matrix displays on -stream this Spring. write a line at a time and require parallel inputs. If polysilicon drivers are to he integrated with the displays then new cir- Amorphous or polysilicon cuit design techniques may be required. According to an ISSCC panel. there are two main technology options for building Better memory large flat panels. One is to use amorphous Much consideration was given at the silicon TFTs and the other is to use The ISSCC, held every ISSCC to the conflicting pressures on polysilicon TFTs. selecting different types of memory store, Disadvantage of amorphous silicon is year in February in San principally in relation to the new genera- that drive currents are typically I0(1(1 tions of portable computer. times smaller than with the n -channel sin- Francisco, is the premier The problem is essentially that if you gle -crystal mosfet driver chips needed to use disks. you need bulky revolving world forum for It operate the display. For a mega -pixel dis- mechanisms requiring hefty batteries. play, several thousand connections need announcing advances in follows that the resulting machine is to be made to the active matrix, increasing heavy, large and has just a two or three costs and presenting reliability problems. microelectronics. 1991 hour battery life. Memory chips give the advantages of On the other hand. polysilicon TFTs papers offer drive currents about one tenth those conference lightness:, cheapness and 40 to 6(1 hours of of single -crystal devices and both n -chan- described new integrated battery Life; but your removable storage nel and p -channel devices are available. medium -a card rather than a floppy - little. This makes ít possible to integrate cmos circuits and gave a good is compatible with precious driver and interface circuitry directly on No one seems to have resolved this the glass with the display. greatly reduc- indication of where dilemma yet. although it was pointed out ing the number of external chips and con- electronics leaders are by speakers from Intel that it is possible to nections. produce a chip which is non-volatile, can But Nippon Telephone and Telegraph directing their R&D. David he erased electrically rather than by UV, (NTT) believe that the amorphous silicon and because like dram it needs only one approach could come up against a techni- Manners reports on transistor to make a memory cell capable per panel. NTT's of storing a binary digit, has the potential cal harrier at 1M pixels to a and viev, is that for larger; denser, panels the progress portable to be both dense and cheap. move must he made from amorphous sili- wireless world. The chip is called a flash eeprom (elec- con to polysilicon, integrating the active trically erasable programmable read only matrix, driver, interface and defect -toler- memory) and it currently costs about £7- ant circuits on the same glass substrate. 1O for a I Mhit device. alloy'. ing a credit -

April 1991 ELECTRONICS WORLD+ Wireless World 277 Many Radio Amateurs and SWLS are puzzled. Just what are all those strange signals you can Everything you want ... hear but notidentify on the If. and h.f. frequencies? A few of them, such as c.w., ... to make life easier. RTTY, and Packet you'll know - but what TDS2020 is an ideal way about the many other signals? to save time and money Hoka Electronics have the answer! There are some well designing equipment. known CW/RTTY decoders with limited facilities and high prices, complete with expensive PROMS for upgrading, etc., As a High Performance but then there is Code 3 from Hoka Electronic! It's up to you to make your choice - but it will be easy once 16 -bit Control Computer you know more about Code 3. its on -board Assembler and ' Code 3 works on any IBM-compatible computer with MS- Forth high level language DOS having at least 640kB of RAM. make programming and debugging a pleasure, yet give the 3 Code hardware includes a complete digital FSK Converter execution speed you need in a real-time system. with built-in 230V ac power supply and RS232 cable, ready to use. You'll also get the best software ever made to decode all kinds of data transmissions. Code 3 is the most sophisticated As a Data Logger Module you've little to add to its decoder available, and the best news of all is that it only costs 10 -bit 8 -channel analog to digital converter, real time £249 plus VAT! clock and non-volatile RAM of up to half a megabyte. The following modes are included in the basic -program (with the exact protocols). You will also like the price. Call for full details. Packet Radio AX 25, 50 to 1200 Bd SITOR Automatic Mode A and B (ARO and fEC) Hell: Synchronous/asynchronous, all speeds ARO: CCIR 476, CCIR 625 mode A Fax: Weather charts, photographs with 16 grey ARO -6:-90/98 spec. ARO variant scales at 60, 90, 120, 180, 240 rpm ARQ-S ARO I000S Triangle Digital Services Ltd Morse: Automatic and Manual speed with wpm ARO-Swe: CCIR 518 variant indication ARO -E: ARO 1000, ITA 2-p Duplex 223 Lea Bridge Road, LONDON E10 7NE Press OPA: Fib spec., 300 Bd ASCII ARO -N: ITA 2 Duplex Wirtschaftdienst: F7b spec.. 300 Bd ASCII ARO -E3: CCIR 519 ITA 3 Tel 081-539 0285 Fax 081-558 8110 Sport Information: F7b spec., 300 Bd ASCII POL-ARO spec. ARO -variant

Autospec : MK's I and II with all known TOM 242: CCIR 242 1/2/4 channels interleaves TOM 342: CCIR 342 1/2 4 channels OUP ARO: Artac ITA2 FEC-A FEC 100(A) ITA2-P FEC Broadcast TWINPLEX Fib! ... F7b6 Simplex ARO FEC CCIR 625 476-4 mode B Sitor both ASCII ITA 5 all speeds, parity collective and selective FEC. Baudot: ITA 2 plus all types of Bit inversion, at FEC-S FEC 10005 ITA 3 1F any speed All modes in preset and variable user -defined baud rates and CIRCLE NO. 135 ON REPLY CARD shifts. Five options are available to use with the Code 3 and consist of: TELECOMMUNICATIONS. EQUIPMENT 1: OSCILLOSCOPE, this facility displays the measured frequency versus time, including split-screen, storage and TEST GEAR. COMPUTERS, ETC non -storage modes at £25. 2: PICCOLO MK VI (Everybody wants this facility, but it's only MONTHLY SALE CATALOGUES OF SURPLUS, on offer from Hoke), the well-known multitone-mode at £60. 3: ASCII 'SAVE TO DISC' Store all decoded text to Disc as SECONDHAND AND REDUNDANT EQUIPMENT ASCII. £25. AVAILABLE ON ANNUAL SUBSCRIPTION OF £5. 4: COQUELET (Another multi/tone system. Only on offer from HOKA!). £60. ITEMS INCLUDE: 5: SPECIAL ARQ/FEC. Various other ARQ/FEC systems. £80. Plus many other special codes. Send for details, price on SCOPES, SIGNAL GENERATORS, POWER application. Along with the many facilities listed above, the analysis SUPPLIES, POWER METERS, DVM'S, section of the Code 3 offers you a wide choice of unique COMPUTERS, VIDEO MONITORS, SCIENTIFIC facilities such as: a built-in AF frequency spectrum -analyser for shift measurement and tuning, plus precision speed INSTRUMENTS, PRINTERS, MULTIMETERS, measurement up to 0.0001 Baud resolution. Other analysis facilities include Speed Bit analysis, Speed Measurement, COMMUNICATIONS RECEIVERS, COMPONENTS, Character Analysis, Auto -correlation of MOD and RAW signal, Bit Analysis. All these state-of-the-art features are CONNECTORS, SEMI -CONDUCTORS, ETC.... included in Code 3 to assist the experienced user. All options are available from the main menu, saving or loading to or from hard or floppy disk in RAW Bit form (no PLEASE NOTE: ALL EQUIPMENT IS SOLD AS loss of unknown signals), hard copy with printer, on -screen tuning indicator and very easy to use online Help -files. SEEN AND THEREFORE, MAY NOT BE IN To order, phone us for more details or send cheque, WORKING ORDER. LOTS CAN BE DESPATCHED payable to: HOKA Electronics HOKA Electronics (UK) BY POST AT COST PROVIDING THE ITEMS ARE Feiko Clockstr. 31 84 Church Street NOT TOO LARGE OR HEAVY. NL-9665 BB Oude Pekela Langford, Biggleswade, The Netherlands SG18 9QA, Beds Tel: 010-31-5978-12327 Tel: 0462-700644 Fax: 010-31-5978-12645 Fax: 0462 700893 B: BAMBER ELECTRONICS, 5 STATION ROAD, Please specify disk size 3'/2 or 5'/á' when ordering! LITTLEPORT, ELY, CB6 1 QE All prices ex. VAT and Shipping; price includes a free 6 -month software update and life -time tech. support. TEL: ELY (0353) 860185

CIRCLE NO. 134 ON REPLY CARD CIRCLE NO. 136 ON REPLY CARD

278 ELECTRONICS WORLD+WIRELESS WORLD April 1991 UPDATE

card -sized 1Mbyte memory card to be Storing analogue wavefo-ms directly made for £56-80. Chips for computer memory storage are not to -A corverters in storing analogue signals the only new kinds of storage chins under and is s.aid to allow storage of eight times Cheaper flash memory current examir ation. more intormation than can he achieved by £80 is a heavy price for a removable stor- For the first time, a chip has beer present- digital techniques. In other words, using digi- age medium, but to bring down future ed which stores analogue waveforms without tal technology, a 1 Mbit chip would he need- any need for conversion into digital form. ed to offer equivalent storage to ISD's 128K costs Intel is projecting a very quick climb Silicon Valley start-up company Information device. up the density scale for flash chips to Storage Devices described a technique to The chip can interface directly to a micro- 4Mbit in 1992 and to I6Mhit in 1994. store 16s of analogue waveforms at 8MHz phone or loudspeaker without the need for As if to demonstrate that such a using 128K eeprom cells. other active components and reproduction is timescale is possible, Mitsubishi gave a The technique eliminates A-tc-D and D - claimed to be better than telephone quality. paper at the conference describing a Short cut: direct storage of analogue waveforms without need for A -to -Ds. I6Mhit flash eeprom which could he made in a similar manner, and so for Sample much the same cost, as a conventional Ck ADDRESS REGISTER CK CHARGE GEN eprom (erasable programmable read only .1 L PUMP memory - erased by exposure to ultra SAMPLE AND 1 -OW WAVE VOLTAGE violet). SHAPER REGULA INPUT COLUMN OLIVER LOGIC Credit -card -sized memory cards (some- 1 1, comma MULTIPLEO:R times called solid-state discs) with up to FLED 24 eeprom chips. suggest the possibility REFERENCES L O D NONVOLATILE of a removable storage medium providing U ADDRESS A E ANALOG T N CONTROL VOLTAGES hut INPUTS . 48Mbyte of non-volatile electrically O STORAGE H erasable and alterable memory. -7 E i -7 ARRAY a -^ E OSC FILTER As well as being useful for removable _ TEST memory storage. it was argued at an LOGIC

ISSCC evening session that flash chips M 0161R. fixed, internal ANALOG 'ILTER U could become suitable for INPUT cx in The - it> = storage computers. justification AGC was that cost -per -byte of flash chip stor- age was on a steeper learning curve than the cost -per -byte of hard -disk storage. An Intel panellist projected that by 1996, with the ñ4Mhit chip generation, the cost of Advent of chips to accomplish this aim panel. wireless private branch exchanges flash would be less, byte -for -byte, than has seen prices of equipment drop dramat- (PBXs) could become a reality during the the cost of hard disk. ically -a process which will continue. 1990s. Such PBXs would need to operate According to UK's Shaye in the GI Iz range and would allow com- Communications Communications. at an ISSCC evening munication from anywhere in a building The ideal for personal communications, discussion session. 1991 will see an to anywhere in the outside world. summarised at ISSCC by NTT, will he explosion in the market as manufacturers All in all, the message from 1991 when: "Anyone can communicate instant- produce standardised products based on ISSCC was a little different from the tra- ly with anyone else anywhere else". The the cordless telephone 2 (CT2) system. ditional ISSCC message of "Look what medium for achieving this ideal is Overcrowding of the frequency spectrum we can do". This year it seemed to he say- advanced cordless telephony using radio has meant these 'phones are moving from ing "Look what we can MM. y'ou". waves. the 45MHz hand to 902-928M1Iz. Instead of technology for its own sake, the At the moment the US cordless tele- world's electronics leaders are at last Combining analogue and digital phone system uses analogue techniques, focusing their thinking on serving the but digital systems are needed to cope shape of a future world, where electronic with the demands on available channels. products are pocketahle and wireless. One of the chip technologies needed to achieve low-cost, lightweight portable tele- Two systems are proposed for a digital phone equipment is the amalgamation of system in the USA: time -division multiple analogue circuitry and digital circuitry on access (TDMA) amd code -division multi- one chip. ple access (COMA). At the ISSCC, a panel session devoted to TON A use, quadrature phase shift key- mixed -signal technology addressed the ing (QPSK) and CDMA uses frequency - question: "Can simulation ensure first -pass silicon success?". Its conclusion was "so hopping spread -spectrum techniques, far, no". which are also used for Europe's proposed Editorial survey: use the information group special mobile (GSM). card lo evaluate this article. Item B. By using microcells. according to the

April 1991 ELECTRONICS WORLD + w IREI.ESS ORI.0 279 AUDIO DESIGN

J

ID i hoe n1 zuam ta as-. T . Itt4:13.tat ME i I MI 1=3 EE I 14 o ir1_rrr t ,' : : i . . t !11

y`(

''41tÁ

,r 3 o .4,A.* \\ , L,f - --- - ``_```;1111i11111>y :-.. r ._...._._. . INSIDE MIXERS

Alarge mixing console arguably A top -end mixing clear view as to what is really necessary to represents the most demanding meet a demanding specification: in other area of audio design. The steady console should words the way forward is to use conven- advance of digital media represents tional parts in an unconventional way, demands that every part of the chain that the highest rather than simply reaching for the most takes music from performer to consumer form of audio design. expensive op -amp in the catalogue. must be near -perfect. as the comfortable Technical problems that must he over- certainty that everything will he squeezed Soundcraft's chief come in a professional mixing console are the through quality bottleneck of either many. A large number of signals flow in a analogue tape or vinyl disc now looks designer Doug Self small space and they must be kept strictly very old-fashioned. describes the apart until the operator chooses to mix Competition to sell studio time them: crosstalk must he exceedingly low. becomes more cut-throat with every pass- technology of acoustic ing week. and it is clear that advances in Sonndcrafl's Series 3200 mixing con- console quality must not harm cost-effec- excellence. sole, which the company claims to he tiveness. The only % ay to reconcile these possibly the hest -performing instrument demands is to innovate and to keep a very ever built.

280 ELECTRONICS \VORLD April 1991 AUDIO DESIGN

Up to 64 input channels, each with many AUXILIARY SENDS; FOLDBACK AND EFFECTS. stages, all have the potential to add distor- tion and noise to the precious signal. Even The auxiliary sends of a console represent phone feed of what he/she is perpetrating, summing these signals together. while an extra mixing system that works inde- which is important if electronic manipula- sounding trivially easy, is in practice a pendently of the main groups; the number tion is part of the creative process, and major challenge. In short, requirements and configuration of these sencs have a essential if the artist is adding extra materi- are much more demanding than those for large effect in determining the overall ver- al that must be in time with that already the most expensive hi-fi equipment, satility of the console. Each send control recorded. In the latter case, the existing because degradation introduced at this provides a feed to a console -wide bus; this tracks are played back to the artist via the stage can never be retrieved. is centrally summed and then sent out of prefade sends on the monitor sections. Major functions of consoles are largely the console. Postfade sends are used as effects standardised, although there is much sends; their source is after the fader, so will be faded down at the scope for detailed variation. Figure 1 Sends come essentially in two kinds: that the effect shows the system diagram, and the tech- prefade sends, which are taken from same rate as the untreated signal, main- nique of multi -track recording is before the main channel fader, and post - taining the same ratio. The sum of all explained in the panel. fade sends, which take their feed from feeds to a given bus is sent to an external returned Figure 2 shows a typical input channel after the fader, so that the final level effects unit and the output of this many channels for a mixing console. The input stage pro- depends on the settings of both. There to the console. This allows vides switchable balanced mic and line may be anything from one to twelve sends to share one expensive device (this is par- inputs; the mic input has an impedance of available, often switchable between pre ticularly applicable to digital reverb.) and is more than the alternative I -2kí2, which provides appropriate load- and post. Traditionally, this means labori- often appropriate into ing for a 20052 mic capsule. while the line ously pressing a switch on every input of patching a processor the channel input has a bridging impedance of not less module, since it is most unlikely that a mix- insert point. than IOW. This stage gives a wide range ture of pre and post sends on the same of gain control and is followed immedi- bus would be useful; the 3200 minimises "Effect returns" may be either modules ately by a high-pass filter (usually -3dB at the effort by setting pre/post selection for in their own right or a small subdivision of 1001Iz) to remove low -frequency distur- each bus from a master switch that con- the master section. The returned effect, bances. trols solid-state pre/post switching in each which may well now be in stereo, the out- The tone -control section (universally module. put of a digital reverb., for example, is usu- known in the audio business as "EQ" or ally added to the stereo mix bus via level equalisation) typically includes one or Prefade sends are normally used for and pan controls. EQ is also sometimes more mid -hand resonance controls as well "foldback"; i.e. sending the artist a head - provided. as the usual shelving Baxandall-type high and low controls. Channel level is con- generate trolled by a linear fader and the panpot noise pickup in long cables and sets the stereo positioning, odd group Microphone inputs minimal internal noise. It must also be numbers being treated as left, and even as The microphone preamplifier is a serious able to withstand +F48V DC suddenly right. The PFL (prefade-listen) switch design challenge. It must provide from 0 applied to the inputs (for phantom -power- routes the signal to the master module to 70dB of gain to amplify deafening ing internal preamps in capacitor mics) independently of all other controls; a logic drum -kits or discreet dulcimers, present while handling microvolt signals. The bus signals the master module to switch an accurately balanced input to cancel Soundcraft approach is to use standard the studio monitoring speakers from the normal stereo mix bus to the PFL bus, allowing any specific channel to he exam- Headphones for in isolation. I n ined ci '1 0 fold back Figure 3 shows a typical group module Electronic oóo Aux 1 keyboard 0 © o Externa a master section; a and Fig. 4 the basics of Multitrack tape machine e fects device manual source -select switch allows quali- Trackl Track2 Track N Aux ty checking of the final stereo recording kuuumuuuulmumumunmo and two solid-state switches replace the Mic Other Stereo stereo monitor signal with the PFL signal sources tape - mach whenever a PFL switch anywhere on the Mic I/p Line Up console is pressed. Mon Group Mon I Group Mon Aux ffect lip 1 lip N Group 2 N N nester »eturn module oAile

System diagram of complete mix- Fig.!. To other console, showing division into inputs, Group groups ing mix group monitor contributions and master se modules. Routeing matrix determines which group of inputs shall he fed to a given track on the multi -track tape machine. Several channels share one Stereo mix bus effects device.

Aux 1 Aux 2

MASTER MODULE INPUT MODULES OUTPUT MODULES

281 April 1991 ELECTRONICS WORLD AUDIO DESIGN

parts, which are proven and cost-effective through quantity production, in new con- 4EY !Phantom power figurations. The latest mic preamplifier ,,on/off Normalled Mid freq insert skt design. as used on the 3200, is new IPFL active signal Input gain i HF PFL enough to he covered by patent protec- B PFL bus tion. Mic/ 1 f' Mix line Fader P It is now rare to use input transformers 11 PF L I bus Mic Mic t/p Input to match the low -impedance (I50 -200i2) pre amp amp ""'l"'` Ring.s nd In/cut microphone to the preamplifier, since the Tip .return cost and weight penalty is serious, espe- Line input cially when linearity at low frequencies and high levels is important. The low -

noise requirement rules out the direct use 5!, IGP2 of op -amps, since their design involves compromises that make them at least GP3 10dó noisier than discrete transistors at low impedance. Fig.2. One input channel. Gain control is 70dB This circuit, shown in Fig.5, therefore and tone control is standard Baxandall shelving uses a balanced pair of low -noise, low-Rb type with addition of mid -range lift and cut. p -n -p transistors as an input stage, work- Two auxiliary sends are shown. ing with two op -amps to provide load - driving capability and raw open -loop gain to linearite signal handling. Preamplifier gain is spread over two stages to give a smooth 0-70dB gain range with the rota- tion of a single knob. This eliminates the HF LF switched 20dB attenuator that is normally required to give the lower gain values, not Summing Monitor Stereo source mix bus only saving cost and complication, but amplifier switch also avoiding the noise deterioration and Record Replay Tape input output L CMRR degradation that switched attenua- ©Fader suffer Group `Group tors impose. The result is an effective Rotary Panpot virtual -earth Electronic Multitrack Balanced 2 -band eq level input stage that is not only quieter, but bus balanced alp recorder tape -return amp control also more economical than one using spe- cialised low -noise op -amps. Fig.3. Block diagram of typical group module, showing switching between direct out- put and tape replay for monitoring purposes. EQ Since large recording consoles need sophisticated and complex tone -control variable band-pass filter which allows generated is thus reduced about 6dB. systems, unavoidably using large numbers control of centre -frequency and Q, and of op -amps, there is a danger that the then added back. To improve noise per- number of active elements required may formance, the signal level at all locations Panpot degrade the noise performance. A typical (in all conditions of frequency, Q, and To give smooth stereo panning without mid -band EQ that superimposes a ±I5dB boost/cut) was assessed, and it proved unwanted level changes, the panpot resonance on the flat unity -gain character- possible to double the signal level in the should theoretically have a sine/cosine istic is shown in Fig. 6. A signal is tapped filter over the usual arrangement. while characteristic; such components exist, but from the forward path, put through a state- maintaining full headroom. The noise they are prohibitively expensive and so most mixing consoles use a dual linear Fig. -1. Block diagram of master module, with tape send/replay switching and auto- pot. with its law bent by a pull-up resistor, matic PFL switching. as shown in Fig.7a. This not only gives a mediocre approximation of the required law, but also limits the panning range, PFL since the pull-up signal passes active PFL logic control through the bus wiper contact resistance (usually greater PL than the end -of -track resistance) and lim- bus its the attenuation the panpot can provide Summing amp Mi Record Repla when set hard left or right. This limita- tion is removed in Ir E o the Soundcratl active Tape panpot shown in Fig.7b by replacing the Buffer Ele Ironic Stereo Speaker Electronic pull-up with a negative -impedance -con- ba anted oip¡ Q Speaker volume mix master source PFL switching switch verter that modulates the law -bending fader effect in accordance with the panpot set- mastering Stereo apeI a tape machine ting. making close approach to the sine Balanced tape-TMix law possible. There is no pull-up at the retu n amp J lower end of the wiper travel. when it is not required. so the left -right isolation

181 ELECTRONICS WORLD April 1991 AUDIO DESIGN

using a good -quality pot. is improved from approx -65dB to -90(113. This has 4.48V mic power also been made the subject of patent pro- Feedback conditioning tection. network

Gain2 Summing Ganged One of the main technical challenges in console design is the actual mixing of sig- Mic/line i/p nals. This is done almost (hut not quite) Mir select i/p switching universally by virtual -earth techniques. as in Fig.8a. A summing amplifier with Balanced amp shunt feedback is used to hold a long mix- 30dB gain range ing bus at apparent ground, generating a sort of audio black hole: signals led into this via mixing resistors apparently van- ish, only to reappear at the output of the summing amplifier, as they have been Line i/p summed in the form of current. The ele- gance of virtual -earth mixing. as opposed to the voltage -mode summing technique Fig.S. Low -noise microphone amplifier with wide gain range and balanced line out- in Fig.8b, is that signals cannot he fed put. Transistors in first stage avoid noise problem of op -amps. hack out of the bus to unwanted places, as it is effectively grounded. and this can save massive numbers of huffier amplifiers in the inputs. Boost/cut control central .= flat There is, however, danger in assuming that a virtual earth is perfect: a typical op - R amp summer loses open -loop gain as tre- In Out In

NIC NIC

Cw Summing 1

I L ' I vCw I Mix Fig.6. Parametric liGanged resistorsessisstor mid -band EQ icontrol stage. EQ and cen- 1 -- RI tre frequencies are State -variable Ibl independently bandpass filter variable, being set Ganged control by the parameters Centre frequency of the state -vari- End res RLaw able filters. Summing bus

L quency increases, making the inverting These sum amplifiers have a balanced input null less effective. The 'bus residu- architecture that inherently rejects supply - Mix End res al' (i.e. the voltage measurable on the rail disturbances, which can otherwise resistors J summing bus) therefore increases with affect LF crosstalk performance. frequency and can cause inter -bus As a console grot+s larger. the mix bus in the classic situation with adja- system becomes more extensive. and tal crosstalk cent buses tunning down an II)C cable. therefore more liable to pick up internal Increasing the number of modules feed- capacitive crosstalk or external AC fields. Fig.7. Standard panpot circuit at (a) ing the mix bus increases the noise gain: The 3200 avoids internal crosstalk by the showing how pull-up resistor draws cur- in other words the factor by which the use of a proprietary routeing matrix con- rent through wiper contact resistance, noise of the summing amplifier is multi- struction which keeps the unwanted signal which is usually greater than the end plied. In a large console. which might on a bus down to a barely measurable - resistance of the poi., limiting maximum have 64 inputs, this can become distinctly I20d13. This is largely a matter of keeping attenuation. Arrangement at (b) uses problematic. The Soundcraft solution is to signal voltages away from the sensitive NICs to replace pull-up to modulate law again exploit the low noise of discrete virtual -earth buses. Further improvement with panpot setting. Leftlriglrt isolation transistors coupled to fast op -amps. in is provided by the use of a relatively low increased from -65dB to -90dB. configurations similar to the mic preamps. value of summing resistor; this also keeps

283 April 1991 ELECTRONICS WORLD AUDIO DESIGN

THE TECHNIQUE OF MULTITRACK RECORDING. o Input Mix bus Multitrack recording greatly enhances the through "monitor sections" Negligible which are usual- voltage flexibility of recording music. The availability ly much -simplified inputs giving limited con- of a number of tape tracks (anywhere trol; this keeps the more flexible inputs free between 4 and 32 on one reel of tape) that for material that is actually being recorded. can be recorded and played back separate- One of the major features of the 3200 is ly allows each instrument a dedicated track, that the monitor sections are unusually the beauty of this being that one mistake capable, having facilities almost identical to Current -to -voltage conversion does not ruin the whole recording; only a the inputs and allowing much more accu- single part need be done again. The multi- rate assessment of how the mix is pro- la) track process is in two basic halves; record- gressing, reducing learning time for opera- ing individual tracks (or "tracklaying") and tors. mixdown to stereo. Mixdown.When the tracklaying process is Recording. Normally only one or two parts complete, there are 16 or more separate Input are recorded at once, though it quite possi- tape tracks that must be mixed down to Mix bus ble to dedicate five or six tracks to a drum stereo. Major manipulations of sound are kit. The initial whether Significant sound, captured by a done at this mixdown stage; since the multi- signal microphone or fed in directly from a synthe- track tape remains unaltered, the resulting voltage siser line output, is usually processed as lit- stereo being recorded on a separate two - tle as possible before committing it to tape; track machine, any number of experiments subsonic filtering and perhaps compression can be performed without doing anything or limiting are used, but most effects are irrevocable. Amplifier carefully avoided because they are usually Multitrack replay signals now enter the to restore gain impossible to undo later. You can easily console through the input channels, so that add reverberation, for example, but just try the maximum number of facilities are avail- removing it. able. Linear channel faders set the relative Recording is performed via the input levels of the musical parts, while the rotary tb) modules, this being the only place where panpots (panoramic potentiometers) define microphone preamps are fitted. The inputs the placement of instruments in the stereo are mixed together into groups if required; sound field by setting the proportion of sig- performers doing backing vocals might use nal going to left and right mix buses. The four or five microphones, but these would monitor sections are now redundant, and almost certainly be mixed down to a stereo can therefore be used either as extra inputs Input Negligible pair of groups at the recording stage, so to the stereo mix, perhaps for keyboards, or voltage that only two tape tracks are taken up. A to return effects. l bank of switches on each input module Inverter determines which group shall be fed; this is Virtual The - Unbal mixing. advent of computer 1 output known as the routeing matrix. Combined based sequencers has given rise to the group outputs are then sent to tape; howev- term "virtual mixing". Keyboard/synthesiser er a "group" is usually used even if only one parts of the musical masterwork are not Mix Balanced buss current -to -voltage signal is being recorded, as this is the part committed to multitrack, but instead stored conversion of the console permanently connected to in the form of MIDI sequencer data. This the multi -track. (c) can be replayed at any time, providing It is clearly essential that new parts are means of synchronising it to the acoustic performed in time with the material already parts on the multitrack exist; this requires Fig.8. Virtual -earth summer at (a) effec- on tape and also that the recording engi- one tape track to be dedicated to some tively eliminates cross -talk, since there is neer can make up a rough impression of form of timecode. almost no signal at the summing point. the final mix as recording proceeds. Thus Advantages are, firstly, that this gives Voltage -mode circuit at (b) allows cross- continually replaying already -recorded almost any number of extra 'virtual tracks", talk. Balanced virtual-earth summing material is almost as important as recording and secondly that the synthesiser parts suf- circuit al (e) requires a separate inverter it in the first place. During recording, the fer minimal degradation as they avoid one for each channel to provide the anti- tape tracks already laid down are replayed generation of tape storage. phase signal.

the noise flown. although since it drops as a balanced input: each group has two increases by 3dB. the square -root of the resistor value, at buses, which run physically as close The obvious method of implementing hest, there is a clear limit to how far this together as possible and the group reads this is to use two summing amplifiers and approach will ork before drive power the difference between the two, effective- then subtract the result. In the 3200, this becomes excessive: 4.7kS2 is a reasonable ly rejecting unwanted pickup. The two approach is simplified by using one sym- minimum value. buses are fed in antiphase from each metrical summing amplifier to accept the External magnetic fields. which are input, effectively doubling the signal level two antiphase mix buses simultaneously; poorly screened by the average piece of possible for a given supply voltage. this reduces the noise level as well as min- sheet steel. are rejected by the balanced Overall mixing noise is reduced by 3dB. imising parts cost and power consump- nature of the 320(1 mix buses, shown in the signal level is 6dB up and the noise, tion. Theconfiguration is very similar to Fig.8c. The operation is much the same as being uncorrelated for each bus. only that of the balanced mic amp., and there -

ELECTRONICS WORLD April 1991 AUDIO DESIGN

Performance factors Primary requirements of modern consoles are very low noise and minimal distortion. Since a comprehensive console must pass the audio through a large number of cir- cuit stages (perhaps over 100 from micro- phone to final mixdown) great attention to detail is essential at each stage to prevent a build-up of noise and distortion; the lb) la) most important trade-off is the impedance of the circuitry surrounding the op -amp, fore gives low noise as well as excellent Fig.9. /lard switching withiets in volt- for if mis too high Johnson noise will he symmetry. age mode (a) and with analogue gates in increased, while if it is too low an op -amp the current mode (h), which prevents will exhibit non -linearity in struggling to gate elements from being driven outside drive it. Solid-state switching. their voltage capabilities. The choice of device is also critical, for There are two main applications for elec- cost considerations discourage the global tronic switching in console design. The use of expensive chips. In a comprehen- first is "hard" switching to reconfigure Secondly. there is channel muting: this sive console like the 3200 with many signal paths, essentially replacing relays not a hard switch, since an unacceptable stages of signal processing, this becomes with either jfets (Fig. 9a) or 4016 -type click would he generated unless the signal a major concern: nonetheless, after suit- analogue gates which, since they are lim- happened to be at a zero -crossing at the able optimisation. the right -through TIID ited to I8V rails and cannot handle the instant of switching: the odds are against remains below 0.004% at 20dB above the full voltage swing of an op -amp audio you. The 3200 therefore implements mut- normal operating level. At normal level it path, must be used in current -mode. as ing as a fast -fade that takes about 10ms: is unmeasurable shown in Fig.9b. Note that when gate I is this softens transients into silence while off, gate 2 must be on to ensure that a preserving time -precision. It is imple-

large voltage does not appear on gate I mented by a series -shunt jfet circuit. with Editorial survey: use the information input. Full -voltage range gates do exist carefully synchronised ramp voltages card to evaluate this article. Item C. but are very expensive. applied to the fet gates.

FIBRE -OPTICS EDUCATOR

Versatile training equipment for education and Chelmer Valve Company industry. 30th Year? FIBRE -OPTICS POWER METER Can we supply the part you need? Our stocks are very large but if we do not have It dBm and µW we do our best to get It and we know that cost and service count. scale; battery life Worldwide supplier of hours. ELECTRONIC VALVES/TUBES, SEMICONDUCTORS 500 AND OTHER COMPONENTS FOR SPARES OR PRODUCTION ANCIENT OR MODERN SIMPLE OR SOPHISTICATED FIBRE OPTICS MONITOR

For continuity testing and voice comms.

FAX, PHONE, POST OR TELEX YOUR REQUIREMENTS 130 NEW LONDON ROAD, CHELMSFORD, For further details contact: ESSEX CM2 ORG, ENGLAND ELLMAX ELECTRONICS LTD., Telephone: (0145) 355296/165865 Unit 29, Leyton Business Centre, Telex: 995398 Fax: (0245) 490064 Etloe Road, Leyton, London, E10 7BT. (ELLMAX\ Telephone: (081) 539 0136. ELECTRONICS/ ``

CIRCLE NO. 137 ON REPLY CARD CIRCLE NO. 138 ON REPL CARD

285 April 1991 ELECTRONICS WORLD TECHNOLOGY

CHIPPING AT THE PAST

IIf you saw any of the Down to Earth Archaeology is ripe data by hand, whereupon it calculates 3D archaeology programmes on Channel coordinates and stores them. The Husky 4 before Christmas, you will be aware for automation. A Hunter, a larger and more sophisticated that archaeology these days is pretty hand-held computer, can download data high-tech. Electronics and computers are a typical dig involves from an electronic theodolite and store the routine part of all but the smallest excava- thousands of raw data as well as the coordinates. These tions. systems represent the first stage of They are used throughout a project, positional automation. from electronic surveying and metal detecting before digging begins to recon- measurements Map generation struction with computer -aided design and A big problem with both the Psion and required to 'a 3D animation programs when the dig is produce the Husky Hunter is that they generate finished. 3-D image of the site. coordinates, not a map. Even skilled Now archaeology has beaten electronics archaeologists admit that it's easy to and engineering, and become the first dis- Archaeologist Helen record particular points wrongly and even cipline to use the Gridpad computer in to enter the wrong setup data at the begin- anger. The Gridpad, described in the Geake and ning of the day, without finding out until panel, is a hand-held computer without a technology writer the coordinates have been plotted. keyoard; instead, it has a brass stylus for But the program written by TTD for the writing on its -sized It A5 screen. recog- Elisabeth Geake Gridpad plots a map on its screen as the nises handwriting and can store drawings raw data is collected, so it is much easier and signatures as hit -maps in its I Mbyte bring past and to spot mistakes as they are made. This memory. Its maker, GRiD Computer present together. feature is important because virtually all Systems, believes it to be unique. archaeology is destructive: digging is a The machine is waterproof and fairly once -only exercise. And there is never rugged (it will survive being dropped) and enough time for a dig, so anything that was designed to be used like a clipboard. saves time is to be welcomed. But it also has a nine -pin serial port, so by trigonometry. Nowadays, some pro- Only the edges of features are surveyed, can collect data automatically from elec- jects use electronic distance measurers such as the outline of a stone pavement. tronic instruments. (EDMs), which eliminate one of the mea- Using conventional methods, the survey Richard Trainer, of Loughborough - surements and one of the calculations. coordinates are plotted onto a dimension- based Tangent Technology Designs The lucky few have combined electronic ally stable plastic film called Permatrace. (TTD), thought it would be ideal for col- theodolites and EDMs. Then details such as individual paving lecting data from theodolites, which are But frequently. in archaeology, that is stones are drawn on by hand. These must used extensively by archaeologists. A sur- where the technology stops and the long- then he digitised if the map is to he stored vey must he done as a site is excavated, suffering people doing the survey must on a computer - work which is usually mainly to record unexcavated conditions write down the raw data by hand and cal- saved for the winter. But because the to show where the excavation is to he culate the coordinates of the test point Gridpad has a digitising screen, drawings done. After a dig, the soil is replaced care- later. Waterproof paper is used when it can be done on the screen, which automat- fully or, more often. the hole ís filled with rains! ically digitises them. foundations for a building and it is diffi- Fortunate ones, oil better -funded pro- Trainer said "If you take the Pad on cult to see where the dig took place. jects, have been using Psion Organisers or site, you don't need to digitise. By the Theodolites are set up at reference Husky Hunters in the field with their elec- time the site has been excavated, all the points related to grid references. They tronic theodolites and EDMs. The Psion, a data will have been digitised." One tenth measure two angles and a height is mea- very small, simple, hand-held computer, of the York Archaeological Trust's post - sured with a marked staff: from this, the costs around £80 and is used like a pro- excavation staff are currently employed in distance of test points can he worked out grammable calculator: you tap in the raw digitising -a significant expense.

286 ELECTRONICS WORLD+WIRELESS WORLD April 1991 SCIENCE

r

,I

11 A

f

c t ,-01§§011 -4

J

If any surveying has been done in the GRi1Pad's screen. showing a map of a Tumulus, with contours. past. this data can be loaded into the Pad at the start of the survey to avoid repeti- tion TTD software also allows zooming t in and out and panning and can glue Ea..' together the work done by two people on , -r.:ti \ adjacent areas of a site. "It's like taking a 4 ''7. ).` cad package out with you. said Trainer. y . - ' I `. -} - W-5,,-3 A rather more glamorous aspect of ; . V ~ archaeology than surveying is finds - the 1 r items recovered from the excavation. 1.1 which fall into two categories: bulk finds. - ' such as pottery sherds. flint and hone: and s small finds. which are usually the interest- , U,'. ing things such as jewellery and coins. The only record made of most hulk ~, 1. fin,.is is in which layer of earth they were Ems; 44, foLnd. since the conventional method of s recording a small t:nd is to sur\ey its ell r'' position in the ground and then to put it in a marked plastic bag for cleaning and cat- - alogaing. With the Pad and TTD's software. the o '. I; position of a small find can e marked ; - directly onto the map shown on the Pad's ,1--alt % _v screen. using the brass stylus. Then a description can he written onto the screen, which is stored in a file associated with the point on the map. Raw data is entered by means of' a stylus and is then digitised as the work proceeds. The advantage of all these time -saving GRi!)Pad then plots a map of the dig on screen.

Apri 1991 ELECTRONICS WORLD 287 TECHNOLOGY

While it is difficult to raise money for a dig (and harder still in a recession, when little property development is going on), the post -excavation funds which usually An electronic clipboard is probably the most characters, using a combination of two finance the map -making stage are even accurate description of the GRiDPad. It is methods, segment -then -recognise and more scarce. Post -excavation work is as about the size of an A4 pad, with a screen recognise- then -combine. In the first, the important as the dig itself; if the dig is not about A5 size and looks like an Etch -a - computer combines the strokes that go to published, it is worse than not digging at Sketch. A brass stylus, attached to the Pad make up a character and recognises the all, as digging is destructive. by a wire, is used to enter data, text or whole character at once. In the second Andy Copp of York University is a sketches simply by writing on the screen. method, the computer identifies strokes as supervisor at Sutton Hoo. in Suffolk, at Liquid crystal "ink" appears where the they are written and gradually builds up a the site of the famous Saxon ship burial stylus has been; any mistakes can be picture of which character is intended. The and associated cemetery. He commented: crossed out with a vertical line, whereúpon technique used here is called elastic match- "At the moment, we may he recording the they disappear and the correction is written ing. minimum amount of necessary informa- instead. The stylus acts as a mouse too, Jeff Hawkins, an ex -neural biologist who tion )during an excavation)." If it took less when it is tapped gently on the screen. designed the algorithms for the GRiDPad, time to process the information collected, The screen itself is made of two layers, a said it "works on one character at a time. archaeologists would he able to gather conventional LC screen and a layer which But the algorithm is so fast that we take a more evidence about the past. detects the position of the stylus. This guess at the character and try to match it Copp also pointed out that faster pro- upper layer consists of glass with an undu- with a template, grouping several strokes cessing of the data might allow archaeolo- lating surface and a conducting compound, together." gists "to take the work one stage further antimony oxide, in the "valleys"; when the At the heart of the Pad is a standard PC - and draw reconstructions of buildings. stylus touches the screen it completes a cir- compatible with an 80086 processor run- This would involve both )site) plans and cuit. To detect its position, 5V is applied ning at 10MHz and 1Mbyte of system ram, the finds to see if you could, for example. across the screen horizontally, then verti- and it can be converted to an ordinary lap- identify post -holes which belong to the cally. GRiD says the screen is difficult to top machine by plugging in a keyboard and same building. You could use AutoCAD". scratch and should not wear out. monitor. It can be programmed like this, or The beautiful, sophisticated reconstruc- The Pad can recognise handwriting in programs can be loaded via an RS -232C 9 - tions seen on the Down To Earth pro- the form of block capitals and numbers, pin serial port and the LapLink program gramme were produced by an alternative even if they touch; if a character is unclear, stored in rom. Instead of floppy disks it has to AutoCAD-3D animation. Imagic, a the software will choose the most likely one. two removable IMbyte ram cards. The TV graphics animation house, used Soft GRiD says some users have to alter their screen has a resolution of 640x400 for both Image software running on Silicon handwriting a little to help the Pad along. display and pen position sensing, which is Graphics' Iris workstations to give the It converts handwritten symbols to Ascii marginally coarser than VGA. viewer the impression of, for example, walking around a reconstructed house. and village by the This technique could he the next develop- suitable theodolite and EDM, such as church built Crusaders. ment in archaeology: (MAGIC is working Zeiss's Elta 6 Total Station, is about "Gridpad made the work much easier," says the on a couple of projects commissioned £8,000. Total Station is much more accu- Trainer. "We surveyed site in directly by archaeologists. rate (to 3mm over Ikm) than necessary for three days; it would have taken months this type of equipment, but it is compara- without the EDM, Pad and software." 50 000 points tively simple for an electronic theodolite. Gloucester City Council's assistant Trainer is not an archaeologist himself, The TTD and Total Station system was archaeology director, Malcolm Atkin. has but a software engineer. He spent about a designed to he easy to use. "It takes about used an early version of the system to year and a half writing the code for the a day to learn," claimed Trainer. "It pre- build up a contour survey at two sites. GRidPad in C and Pascal, with advice vents a lot of mistakes because you can One was the Norman castle in the city - from archaeologists, one of whom is his see what you're doing and there are pull - a rather confined urban site. The other, in wife. He estimates that the Pad can store down menus and help messages." contrast, was in the countryside, plotting the equivalent of more than 50,000 points. Gridpad may he able to help archaeolo- areas where a magnetometer was to he "It would be hard to make more than gists over the computer phobia which used. 1,500 measurements in a day, so the Pad many of them suffer from, but Trainer Atkin said that on the latter site every- could store about a month's work." he warned that the Pad could introduce prob- thing could he done from one position. so said, though he expected most people to lems not seen before: "Essentially we are the archaeologists didn't have to wander download their data to a host computer at getting rid of paper and that produces all over the fields with tape measures. But the end of every day. phobias." he said the main advantage of the system Trainer said some archaeologists have was its speed: "We're always under pres- bought laptop computers for use on site, Data on site sure of time and we need absolute accura- but they are rather delicate, not water- So far, the system has been tried out in cy. It will make an enormous difference to proof and could easily run out of battery Israel and Gloucester. At Tel Jezreel in 0111 work." power before the end of the day. Israel. the British School of Archaeology One of the major reasons that it is tak- in Jerusalem and Haifa University are ing so long to automate archaeology. of working together on a large and complex course, is cost. Most projects set money excavation. The site measures 200m by aside for EDMs and computing resources. 600m; it is mainly iron age. with a palace but will they be persuaded to part with built by Jecreel, who is mentioned in the money for the Gridpad? The Pad and soft- Bible, and includes a chalcolithic village Editorial survey: use the information ware cost around £3,000 together and a (from the fifth millenium BC) and card to evaluate this article. Item D

288 ELECTRONICS WORLD + WIRELESS WORLD April 1991 Leader Video Monitors

00 0 and o-po _oo ó , Generators e.

' 1 lea ------7." Lg 0 - - - _- G.Li////.í17Dfi

. 411 ;'. or -- : _:.. 03 1111 í ioa o rrjqjv 1. I. AL ------,.®. 11.1 fl . . . o o o é . .. , J + 5851V Fully featured PAUNTSC vectroscope £1,788 The Leader range of video 5861V Fully featured PAUNTSC instruments represents the state of waveform monitor £1,505 the art for both broadcast and non - 408P Advanced pattern gen. THURLBY broadcast applicat ons. with Genlock £2,443 5871V Combined VectorscoFe Our illustration shows just five models and waveform monitor £3,664 THAN DAR from the large range. They are (left tc LC399A Pattern generator right): PAL B £939

Thurlby-Thandar Ltd., Glebe Rd., Huntingdon, Camts. PE18 7DX. Tel:10480) 412451 Fax (0480) 450409 Telex: 32250

CIRCLE NO. 140 ON REPLY CARD

U SWITCH MODE POWER METEX PROFESSIONAL DMM's auuNDnit ltIIli SUPPLIES

3'h and 4'h digit LCD large display (17 MODEL RANGES BASIC EXTRA FEATURES PRICE I AVAILABLE IN QUANTITY - mm) Dam's. AC/DCto 20 Amps

- FROM STOCI to S 3800 32 0.5/o LO AC/DC UA £1$.50 Resistance 20 Mohms ranges (UK um/peck/In.. AC/DC Volts Me Transistor Test n.19Ior 1, 2 oe 3) 3610 30 0.3% £35.35 ° ,T.,.e Diode Test Continuity Auto I Polarity and Zero With test leads, 1 -rn `4TYPE1 3630 30 0.3%o. Cap Test x.60 r, Hard carry case and * `OPEN CHASSIS" PE Instructions. 3630B 30 0.3% with Bargraph £49.00 ' yy Output 5 volt 8 a mp, Ii 12 0.5. INSTRUMENTS 3650 30 0.3% Freq. Count 8 Cap £42.45 - volt amp. NEWND x.18 BENCH wthDtobes) 533800 Size7.7x42x1.1 it SCOPES Hi ylopp TESTERS NAMEG 3650B 30 0.3% with Bargraph £9.50 u'neTs í.2..r7% Size7.7x4.2x1. ins meters DuallraceMHZ C792 "POCKET" dal 11 puallrace pl m I 1. N TYPE 2 1gs 3ROr9a12mmLCDor9 10053Cbanne10a9e 4600 30 £53.85 Cont. C!5 0.05% Data Hold M27O818Ran9eé0AADC ]2.74 205170ua120 VOdaple ASTEC Cont IL 1 f M2315811Ran9 a CarlyCase potecnscopesa [p900 L gi_ ty12 ScoDeS 4630 30 0.05% Cap Test. Data Hold £x.20 I M2316B23Ran9e10ADC AllHdaCNMone156 pTS ENCLO EDOX r MZ33511Ran9el0AIDCContteCone H1e 'CDualMSMHZBañlMamss1°LED 174.57 30 0.05% with Bargraph £9.25 II M2Ra getOAIACDDC 0109>MI Three pin Col Plea pt25 FREWENCMHUNTERSBD9 .1135 mains socket -' - re Ran9e10ÁlACIOC CIIE. 4650 . M236538 Lo9Cies1 nedo, MEl11600 30 0.05°/n Fret 8 Cap 8 Data Hold £(íi.25 input, on/off ' ' Freq mmand5,9' 1 Hle tout .11214 MEpp1000*WOO MMHZ switch. Output -5 volt 3.75 amp, Slur°y 018.10 ME19016RangqeOOmni 1y10MHZ 4650B 30 0.05% with Bargraph £71.55 12 volt 1.5 amp, -12 volt 0.4 amp. AL12610PDC Omm F2118 ME115 t110.10 GENERATORS 115.230V A/C Intut Size 7.0x5.3x2.5in pMSiHINAutérAu10rangeDmm FUNCTION p2P5 t110a10 M818 True RMS AutorangEr 33/e Digit NC31Pen1y0 TS J.pIHZto9lUKH2 BRAND NEW £1 .27 ' yF20BualScaleSoundLevelMe1e' 1200002HHZwMMHZ Cl Data hold. Hi/Lo Frequency £4.15 el 01683al ALSO STOCKED. Public Address Equipmi nL yVHStaILoaMetere31Ran9es 1G10202ÑZto2MHZ .1ZB1 M818B As above with Bargraph £4,3.85 1065D,9 01475 GENERATORTV-VIOEO g F HI-FI Disco Spealers. Microphones. Mixe 01LgCProb° VDlus and Graphics. Security Alarms. Doorphones. OdonPilNHFIUBF M625 Lg'c PrMe ePu1FpO5eA1300 LCD 3`h Di911 ,,,..../.,,,ni OMM's Intercoms. CCTV Tools and Components. 7qlAtClam:RessRan9Range BENCH tti TIMERS, RELAYS AND FANS Cl6. S21pirueRMSO Accessories for 7V. Video. HI -Fl. Telephones. Ranggelock IamDQ1ode 3,n5p25w,Bavc M265AddonC AmOS - Audio and Computer. 011999 tp86 Axial Fans Dmm lauontester5NV ¡M35101%Bas,c U0320 m stocl 501EIectromCllnsulabonlesterllpOV 04188 L85BO lo' GENERAL 220/24)V A/C. 5plElecuomC q612 JOWLCRACBnd9e j120 110/12)V KOmB¡RDrDMeeºatureEMn d M30028ACMApvoftMeeerIMHZPIus6D,9it TLDIy . . 1p62LCDlemO A/C. 11 Volt PAP% pnasetester meb' 4162A0150MHZRFGen All type s of Relays. Low , d ÉSF C4343 and 24 Volt. Dpnal clam: Ptusó 9 .115110 Voltagv,110/240V A/C DIL., :. AND ,, AC SPECIAL MáppA t29.35 3Ap1MM2counter AF Gen '""\ Various ACvolts 2(>6 PLUGIN, PCB Etc. I n FOR PITIES tescer 10' OCTAL, EDUCATION D0lahotdResa RF Gen 11350 sizes n msulabonw,tpDwellatd C4S 70 counter Also -10 and 240 V A/C - 261Aodo 150M [1110 20 TEND ;1gp110LCDOm ACIDC t timers. ces tortes' December 1990 A4 15% VAT UK only Á nMeter 145 14111 Generator UOUL SEND t1m 1 udro Meter FpR tacnRan9es20 eOaDacita C52 u 9 MtW tE2201 nalCaD CATALOGUES ¡SpLCD 8Ra Power L5.p U`9 K 10000 Auloran9e ¢ctor UAW 5(,6pLCD0,9ilallme 01261 S,9naiDlg1Fieq.Co un ter R Send A4 -Fut=er t2611 SAE 2 1312Ran9eMM tOADC RY S faUfJlO ELECTROf11CS (UK Stamp f100 2p1p19Ran9eMM su ruts 1á6 FEl PPLIES PSU 41 Range pp pp ER t8955 I 5p5pt a0able 404 Edgware Road, London W2 1 ED. -el: 071-724 3564 t520 2430124V013AVa0ab1ePSU MOO Mk RQ sw) C953 24501244015 t,g995 6 days a week callers and orders. M200P200MHZ8De9i1LEDCouNerSub t VxOable150p1eP5U Open for Telephone PF "Nat- Rests. 367 514115V014A us so 7 ORS10" CI aEEto c l. `enlSnodCCi7o p$j030130V01359003 018110 Trade/Industry/Export Supplied. Quantity 11ry s' UP OCISC Kd ver5mn4 s and Education obe 3113 Economy Mele E11E10 Ivers,on ' Enquiries Tel: 071-2581831 FAX: 071-'24 0322 PS363O Dual CIRCLE NO. 139 ON REPLY CARD

April 1991 ELECTRONICS WORLD+ WI RELESS WORLD 289 SPECTRUM ANALYSERS RALFE - ELECTRONICS HEWLETT PACKARD 36 EASTCOTE LANE, S. HARROW. MIDDLESEX HA2 8DB ..... TEL: 081-422 3593. FAX: 081-423 4009

l 3 I . 01 _

i I , ` fC r-rlpi ``_: 1.. EST 35 116028 transistor fixture for S -parameter test set HPI82C/85588 0.1-1500MHz £2500 YEARS £395 HP182T/8559A 2IGHz system £5000 r - 11710 frequency down -converter for 86408 sig' gen' HP3582A 0.02Hz-25.5kHz £3500 £750 HP3585A 20Hz-40MHz £7500 3400A milli -voltmeter l OHz-10MHz true RMS £250 15Hz-50kHz £1000 HP141T/85528/8553B 110MHz system £2000 GOULD 0S4035 digital storage oscilloscope £750 358IA audio wave analyser P -band attenuator 12.4-I8GHz 0-5008 £250 HPI41T/85528/8554B 1250MHz system £2250 NATIONAL VP -7750A wow & flutter meter £225 382A1P) mV -Meter Is. 20Hz-4MHz £325 HP14IT/8552A/8555A 18GHz system £3250 PHILIPS PM5534 standard pattern generator NTSC £2500 400FL 100pV-300V 4204A oscillator 10Hz-1 MHz £125 PHILIPS PM5545 colour encoder PAL £1000 decade 435A/8482H microwave power meter £650 PHILIPS PM5597 VHF modulators £250. PM5598 UHF £500 4329A high -resistance meter £750 MARCONI INSTRUMENTS PHILIPS PM5580 I.F. modulator £1500 4342A Q-meter 22kHz-70MHz. Q-range 5 1000. £1000 PHILIPS PM6613 250MHz counter/timer 8 digits £150 4948A impairment (TIMS) tester £3000 2017 signal generator 0P -controlled GPIB £3500 PHILIPS PM8202 recorder with 9874/01 temp' unit £450 in -circuit transmission multi -meter, £1750 2019 synthesized signal generator (GPIB opt) £2000 RACAL 9081 signal generator 5-520MHz synthesized £850 50058 signature programmable -timer £150 2091C/2092C white noise receiver/transmitter, pair £1750 RACAL 9082 signal generator 1.5 520MHz synthesized £950 5300A/5302A 50MHz counter 2356/2357 level oscillator/level meter £1000 5363B time-interval probes £ 1250 RACAL 9082H 1.5-520MHz high power sig' geni synthesized £500 2370 spectrum analyser 110MHz £2950 £1000 5384A 225MHz system frequency counter GPIB supply 0-40V 0-5A £250 2380/82 400MHz spectrum analyser £11000 RACAL 9084 synthesized signal generator to 104MHz £650 62668 power 6516A power supply 0-3kV @ 6mA £250 2431A 200MHz frequency counter £110 RACAL 9105 RF micro -wattmeter 0.020W-200mW £250 7440A (002) HPIB A4 plotter £450 2438 (3033) 520MHz universal counter timer £450 RACAL 9300 RMS voltmeter -8048 to +50 £ 195 colorpro 80138 pulse generator 50MHz dual output £750 2501 RF power meter 0.3W DC-1GHz £150 RACAL 9301 RF milli -voltmeter £350 function generator 1 MHz-50MHz GPIB £1500 2503 RF power meter to (00W DC-IGHz £200 RACAL 9301A RF milli -voltmeter £450 8165A test set selector £500 2828A/2829 digital simulator/analyser £1500 RACAL 9302 UHF mV -meter 10kHz-1.5GHz 1000V-3 001. 8327A Voltage & phase to 1000MHz £ 1250 - 2833 digital in -fine monitor £250 £450 8405A vector voltmeter. 110MHz spectrum analyser plug-in £750 2870 data communications tester £1000 RACAL Store 7DS instrumentation tape recorder £1750 85538 in 8600A digital marker generator for 8601 A £325 2955 test set with GPIB option 11 only stock) £3500 SCHLUMBERGER 4010A mobile radio test set £1750 generator 800MHz-2.4GHz £1250 6460 microwave power meter with head 6421 £300 SCHLUMBERGER 4021 mobile radio test set £1950 8614A signal sweeper main frame & 86218 plug-in units £ 1500 6460/1 microwave power meter with head 6423 £350 SHIBASOKU 217A/33 SECAM colour bar generator £325 8620A sweep generator plug -1n IOMHz-2.4GHz £1750 60568 2-4GHz signal source £850 SOUND TECHNOLOGY I000A FM stereo sig gen Band II £500 86222A 0A2805A PCM regenerator test set £750 £450 86408 signal generator options 1.2 and 3 £ 1750 TEKTRONIX 465B 100MHz oscilloscope £2000 TF 1245A Q-Meter with 1246 and oscillators £500 TEKTRONIX 2336 ruggedized 100MHz oscilloscope £950 8656A signal generator 0.1-990MHz generator 2-36.5GHz £13500 TF20028/2170B 88MHz signal generator £300 TEKTRONIX 576 transistor curve tracer £2500 86738 signal transceiver interface £750 TF2011 FM signal generator 130-180MHz £150 TEKTRONIX TDR 1503C options 3 and 4 New £3250 8954A TF2013 FM signal generator 800-960MHz £350 TEKTRONIX 4696 colour ink -let printer (with 4510A) £750 TF2015/2171 10-520MHz AM/FM signal generator £500 TEKTRONIX 7633/7A26/7853A storage oscilloscope £1250 T&M EQUIPMENT TF2162 audio attenuator £100 TEKTRONIX 7L18 spectrum analyser plug-in unit £4750 STOCK EXAMPLES TF2163S UHF attenuator DC-16Hz 0-14248 £325 TEXSCAN VS60C 1000MHz sweep generator £1100 A.W.A. type F242A auto distortion & noise meter £325 TF2175 RF power amplifier 2-500MHz 27dB gain £250 TEXSCAN VS901 5MHz-2400MHz sweep generator £850 TF2300 modulation meter ANRITSU MN95D fibre -optic attenuator 0-65dB £250 £200 TOA PM -30R RF volt -meter 1 mV-IOV fsd £250 & bridge £275 TF2300A modulation meter £300 WAYNE KERR 3245 inductor analyser £3000 AVO CB154/5 electrolytic tant' cap' TF23008 modulation meter £400 AVO RM 160/3 megohmmeter £175 TF2304 modulation meter, automatic £400 AVO RM215L-2 ac/dc breakdown tester to 12kV £695 Alpha II 807R £500 TF2331 distortion meter £150 PLEASE NOTE. ALL OUR EQUIPMENT IS NOW CHECKED BRANDENBURG 0-30kV & 4416 response test unit £550 TF2500 audio frequency power meter £100 TO MANUFACTURERS' SPECIFICATIONS BY INDEPEND- GRUEL KJAER GRUEL & KJAER 2609 measuring amplifier £650 TF2600B video voltmeter I mV -300V fsd £150 ENT LABORATORY TO BS5750. Certificates of calibration BOONTON 1028 AM/FM signal generator £1000 TF2807A PCM multiplex tester £400 to this standard can be supplied at very reasonable cost. All FARNELL SSG520 signal generator AM/FM 10 520MHz £950 TF2905/8 sine squared pulse & bar generator £275 items guaranteed for 3 months (90 days) and 7 -days 'return FARNELL AMM-automatic modulation meter £325 TF2908 blanking & sync mixer £150 for full refund' warranty. URGENTLY REQUIRED FOR STOCK - TF2910/4 video non-linear distortion analyser £750 'high waiting for first -quality FLUKE 80208 handheld DMM £125. 13840A(09) 51/2 DMM end' test equipment, cash £325 TF2950 mobile radio test set £600 instruments. ALL PRICES SUBJECT TO ADDI- second user 0.01-4GHz £1250 TF893A audio power meter £50 TIONAL VAT. GIGATRONICS GUI240A signal source TM4520 Inductor set £250 GOULD.138 audio oscillator £350

CIRCLE NO. 144 ON REPLY CARD l MICROPROCESSOR DEVELOPMENT TOOLS

EMULATORS -SIMULATORS -COMPILERS - ASSEMBLERS -DEBUGGERS -PROGRAMMERS 77C82 8085 Z8 68000 8051 8086 64180 32010 68HC11 87C752 6301 6502 Z80 V20 6809 740 Series V40 80188 etc.

8051 DEVELOPMENT SYSTEMS MITSUBISHI 740 SERIES Pascal, C and Assemblers NEW Integrated:- Multitasking support Assembler Source level debug Editor Supports ALL 8051 variants Emulator with Real Time Trace Programmers including support for 87C751 UNIVERSAL TOOLS Universal Assembler ROM EMULATOR Compilers Simulators ROM sizes from 16 kbit Dis-Assemblers to 8 Mbit! Programmers for PROMs, PALs Full screen editor etc. High speed parallel download Split and shuttle capability Battery back-up shuffle IN -CIRCUIT EMULATORS 68HC11 77C82 8051 8086 NEC V Series 68000 Z80 80188 80186 and more

SMART COMMUNICATIONS 2 Field End, Arkley, Barnet, Herts EN5 3EZ. Telephone: 081-441 3890

CIRCLE NO. 145 ON REPLY CARD

290 ELECTRONICS WORLD+WIRELESS WORLD April 1991 TECHNOLOGY

There are three basic strategies available to execute an IC design in silicon: the programmable logic device (PLD), the full custom E SILICON device, and the application specific IC (asic). Taking the PLD first, this relies on eprom technology and is implemented using a matrix of logic gates. As each TRAIL STARTS device has to be programmed individually and for large numbers of latches, this method is unpractical and expensive. Also, because the internal silicon layout is fixed, gate utilisation is limited and so HERE less circuitry can he accommodated on a single device. Another approach, at the other extreme of the spectrum, is a full custom device. IC design can be The cost of producing a customised sili- Each design is hand-crafted to optimise con circuit is dependent on which of the silicon use and hence improve speed. implemented in technologies is used (Table 1) and how But these devices take a long time to many devices are required. design, due to complexity, and hence are silicon in a variety of Obviously, for low volume batches, the costly to produce. To he cost-effective, ways. Nigel Howell PLD solution would he the most cost- manufacturing volumes must be high to effective since it entails little initial cost cover initial design and tooling costs. explains the pros and layout on production and only incurs costs A trade off between these two options at the programming stage for high vol- is the semi -custom asic which combines cons of different 11111eS. the complexity of a full custom IC with However, a lot of CPU time will be the simplicity of a programmable design. approaches. needed and this could prove expensive. For asics, software has been developed There is little to choose between gate to enable a unique design to he produced arrays and standard cells. But due to the out of a library of gates, with the possibil- constructed from predefined building initial costs of tooling. the gate array ity of fairly cheap manufacture in low vol- blocks which have been tested beforehand method is slightly cheaper for lower vol- umes and the capability for reasonably by the man u fact urer. Designers simply umes and as the volume increases, less complex design. select the combination of blocks required redundant silicon makes the cost of stan- and connect them together. dard cells more competitive, until it Advantages are that because each block becomes the cheapest method. Two sorts of asic has been previously tested. there 's a high If a aesign has been proven and it has There are two main asic categories from probability that the completed design will been shown that there is a market for high which a designer can choose - the gate work first time. Also less silicon is used volume production, then in the long -terns array or the standard cell. because there are no areas of redundant it may be cost-effective to produce a full A gate array is manufactured on a mas- silicon. custom ]C. ter silicon wafer which contains a matrix However, tooling charges a -e more Advantages of this approach are that of logic devices. All the designer does is expensive because a full mask set is less silicon will be used, and the speed of connect these logic gates together in a required in production the device will increase accordingly. unique pattern. In this way the master wafers of logic gates can be mass produced beforehand Table 1. Comparing the route to silicon and customisation is only completed at the final stage of production. Production costs are reduced and there is a faster turnround parameter PLD Gate array Standard cell Full custom in device completion. But this solution does have a drawback No of gates 102 103 103 103 in that there are many redundant logic (complexity) gates because the design routeing can only Design time 2 4-13 6-26 1-2 occur along fixed channels. Silicon (and (years) money) is wasted as a result and the per- Manufacture 0 1-8 6-12 8-16 formance of the device is limited. time (weeks) Practical 1-10,000 5000-50,000 50,000-200,000 200,000+ "call off" Standard cell volumes The alternative approach is to use the Circuit Reasonable Good Very Good Excellent standard cell, where the full asic design is

April 1991 ELECTRONICS WORLD + WIRELESS WORLD 291 TECHNOLOGY

Once the mask -set for production has been fabricated, manufacturing of devices will he fairly cheap and the pros of this method will outweigh the cons.

Non -recurring engineering A parameter not yet considered when deciding which route to silicon to take is the non -recurring engineering (NRE) charge. NRE is a charge made at the out- set of production, which covers technical support, tooling and mask manufacture. It cannot he avoided in asic and so must he considered. The only time it is reduced to zero is when the PLD option is used. For gate -array. standard -cell and full custom options, the NRE charges roughly vary 1:20:10(1 in proportion, respectively. reinforcing the opinion that full custom is only really viable for high volume manu- facture. NRE charge also varies depending on the point that the customer enters the design process. As asics are becoming cheaper and more complex with the advance of tech- Suppliers such as Micro Circuit Engineering can offer a low-rolunte prototype at rel- nology. companies are beginning to atively low cost. choose them as a low risk method of com- mitting a design to silicon. would he reduced and the overall costs available. reduced. Mentor Graphics's Idea system can he Level 5: silicon layout is performed. used as an example. Mentor Graphics is Differing customer leaving only the actual production to com- an American Company who claim to he involvement plete. the largest supplier to the industry. Once the decision has been made to pro- Idea has the ability to create a schemat- duce a design using asic there are five Some companies allow less points at basic levels at which the customer may which the customer may enter the design Table 2. Suppliers of design enter the production process (Fig. 1) process, others more. packages though these options may not apply to all Some companies may he involved only manufacturers. in the design process. some only in manu- Level I: the customer merely supplies facture. Workview the manufacturer with a specification and For example, Rapid Silicon is a compa- Viewlogic Systems Inc the rest of the work will be carried out on ny that will produce an asic design solu- his behalf, from circuit design through to tion to a specification given by a customer Scald prototype production. but will not fabricate the design, only Valid Logic Systems Inc Level 2: the circuit diagram and specifi- helping with its creation. cation are prepared by the customer and In other words, Rapid will perform the Logician the rest of the process is completed by the tasks outlined between levels one to five Daisy Systems Corporation manufacturer-from schematic capture to but will not produce the physical integrat- prototype production. Schematic capture ed circuit. Sunews is the process of transferring the circuit For this final stage the company will Sun Microsystems diagram onto a software database, using help select a suitable silicon vendor and one of the packages discussed later, such arrange to have it produced. Rapid will Dash as Idea by Mentor Graphics. This is then design the circuit on one of a choice of Future Net Corporation used during manufacture. computer -aided design packages devel- Level 3: At this level the schematic oped especially for this purpose. Orcad capture and simulation is performed on an Orcad Systems Corporation acceptable cad system -engineering work- station and the schematic files and simula- Suitable design packages Design Engineer tion listings are given to the manufacturer Manufacturers supply a list of packages Intergraph Ltd to complete the process. that are suitable for their design process Level 4: the customer must not only and also a library of available functions. Phase 182 complete all the previous tasks but also Some packages are shown in Integrated Silicon Design perform the design verification on a pow- It would he too lengthy to discuss each

erful computer such as a Digital Vax. By of these systems' merits and faults. so 1 BX entering at this level, the NRE charges will explain briefly the facilities generally MCE Idea Mentor Graphics

191 ELECTRONICS WORLD +WIRELESS WORLD April 1991 TECHNOLOGY is and also simulate its use. Sample pulses share the production costs for one wafer Table 3 principal UK manufacturers and waveforms are displayed simultane- (in very low volume fabrication). ously on the sank screen. The package is The European electron beam (E -beam) menu driven based on hierarchical meth- system used by Texas Instruments is an Hitachi ods and is, as most are, devised around the example of how the multi -design wafer is Watford, Hertfordshire, WD1 7TB edif (electronic design interchange for- produced. mat). A wafer can be manufactured without a Intel Corp Schematics can be entered in Boolean. mask set. But this can only he used for Swindon, Wiltshire, SN3 1RJ programming language or diagrammatical low volumes, because of the time factor format for good flexibility and the pack- and as volume increases, a mask set must International Microcircuits age has the ability to incorporate libraries he produced. Alencon link, Basingstoke, Hants, of functions supplied by silicon vendors to There are about 300 silicon foundries RG21 1RD allow it to he made specifically compati- worldwide - a list of those available in ble with that vendor. Britain (Table 3) is published by the DTI. MCE Though the exact forms vary. these fea- Micro Circuit Engineering, a supplier Ashchurch, Tewkesbury, Glos., LG20 tures appear on most packages. from Tewkesbury, offers a low -volume 8TB prototype service at a relatively low cost. It produces the physical prototype as a Motorola Final stages gate array in a turnround time of four Aylesbury, Bucks, HP20 2NF Once the design has been produced by weeks. this means it must he verified using a National more powerful computer such as a Vax, Home Lane, Bedford, MK40 1TR Mach -1000 or Hichip simulator. Auto - placement and routeing procedures NEC required before production can begin will Linfordwood Business Centre, Milton also he carried out at this stage. Keynes, MK14 6NP Finally, the software design can he manufactured using advanced production Texas Instruments systems. It is becoming possible t produce Bedford, MK41 7PA several different designs on a single sili- Editorial survey: use the information con wafer. reducing the cost of producing card to evaluate this article. item E a custom chip. as several companies can KESTREL FULL SPECTRUM ELECTRONIC MONITORING

COMPONENTS LTD *min. i , ls rc a . a99.e0o 00 ,,, 0 _ -r * All items guaranteed to manufacturers' spec. ( t - ei * Many other items available. 112 -- tyi[r ri A405. _Pk. -- 'Exclusive of V.A.T. and post and package' .tÍ l =

1+ 100+ 14 100+ Z8530 0.60 0.30 2732A 2.00 1.50 mimmilmm Z80A CPU 0.80 0.65 2764A-25 2.00 1.30 Z80A CTC 0.50 0.30 27C128-25 2.40 1.68 with ICOM's new IC -R9000 radio 2.10 1.42 The world is at your fingertips Z8OB CTC 0.60 0.40 27128A-25 widebond range Z80A P10 0.60 0.40 27256-25 2.10 1.42 communications receiver with continuous all mode, super Z80B (CMOS) CTC 0.80 0.50 27C512-25 3.00 2.60 of 100KHz to 1999.8MHz and a unique CRT display that shows frequencies, Z80A DMA 0.95 0.80 6116LP-100 1.00 0.65 modes, memory contents, operator -entered notes and function menus. The 2.00 1.20 74LSO4 0.12 0.07 6264LP-100 features IF Shift, IF Notch, a fully adjustable noise 3.60 2.45 revolutionary IC -R9000 74LS27 0.11 0.07 62256LP-100ns the widest range, 74LS83 0.16 0.10 74HC 194 0.16 0.10 blanker and more. The Direct Digital Synthesiser assures 74LS86 0.12 0.07 74HC244 0.18 0.14 lowest noise and rapid scanning. 1000 multi -function memories store 74LS109 0.16 0.11 74HC356 0.16 0.12 frequencies, modes, tuning steps and operator notes. Eight scanning modes 74LS138 0.16 0.11 74HC541 0.28 0.20 include programmable limits, automatic frequency and time -mark storage 74LS148 0.18 0.10 74HC574 0.30 0.20 full, restricted or mode -selected memory 74LS151 0.18 0.10 74HC640 0.50 0.30 of scanned signals, a 74LS154 0.28 0.15 74HC40105 0.20 0.12 scanning priority channel watch, voice -sense scanning and 74LS244 0.22 0.16 8251A 1.10 0.80 selectable width around your tuned frequency. 74LS273 0.22 0.16 8255A-5 1.20 0.75 74LS373 0.20 0.14 6502P 2.00 1.56 o Icom (UK) Ltd. Tel: 0227 741741. Telex: 965179 ICOM G 2.00 1.35 74LS374 0.20 0.14 6522P N.B. For Wales and the West contact: 0.18 0.14 74LS399 0.18 0.10 74HCT373 M.R.S. Communications Ltd. Cardiff. Tel: 0222 224167. 74LS645 0.58 0.38 IC All memory prices are fluctuating daily, please phone to Please send information on Icom products & my nearest Icom dealer. 7 confirm prices Name/address/postcode:...... 178 Brighton Road, Purley, Surrey CR2 4HA Tel: 081-668 7522. Fax: 081-668 4190 Job Title: Post to Icons (UK) W Dept. WV, FREEPOST, Herne Bay, Kent CT6 8BRX CIRCLE NO. 141 ON REPLY CARD CIRCLE NO. 141 ON REPLY CARD 193 April 1991 ELECTRONICS WORLD+ WIRELESS WORLD Finally... an exceptional PCB arid Schematic' CAD system for every electronics engineer!

BoardMaker 1 is a powerful software tool which provides a convenient and professional i1u u method of drawing your schematics and

I 3 designing your printed circuit boards, in one R9 cIs 138 9 1:i 6 9,, 10au remarkably easy to use 01222 --.-i ; oKi2 +16v package. Engineers Ti worldwide have discovered that it provides an L R 7cc RQ0 RIO II 12K unparalleled price performance advantage S6R aT ,S over other PC- based systems. 7÷1--

RH RI2 BoardMaker 1 is exceptionally easy to use - its 660R i- 2k 2 sensible user interface allows you to use the 12 I 13 '2:11 13 cursor keys, mouse or direct keyboard C4 - 9n7- 9n7C16- commands to start designing a PCB or schematic within about half an hour of opening the box. HIGHLIGHTS Produce clear, professional schematics for inclusion in your technical documentation. Hardware:

ool -mire rnf 1 i. 4127 IBM PC, XT, AT 100% or compatible. N / I/ MSDOS 3.x. I/ owe nude 640K bytes system II ack a node P memory. wt node 2 HGA, CGA, MCGA, EGA or VGA o nd node N display. re/circle Microsoft or compatible mouse recommended. urrent node a All 19er Capabilities : o Segment aver 1,11 width Segment :Mk IN Integrated PCB and schematic editor. pellt o prof 8 tracking layers, 2 silk screen layers. overt order` O'1 Maximum or - 17 sift track board schematic size 17 x Oio i11 inches. barest pad o, O ' Y\ L1 IN o 2000 components per layout. Symbols can be o =_ moved, rotated, repeated and mirrored. H. " \ p User definable symbol and macro library facilities ó .-. including a symbol library editor. Graphical library browse facility. OT Design rule checking (DRC)- checks the clearances between items on the board. d v I o o , c Real-time DRC display - when 9.tRie W, lac- I/99 45' 11=11 ,- ,of . placing tracks you l r1- f,`:e can see a continuous graphical display of the PCB layout editor provides full analogue, digital and design rules set. surface mount support - ground and power planes Placement grid - Separate visible and snap grid - (hatched or solid)- 45 degree, arced and any angle tracks. 7 placement grids in the range 2 thou to 0.1 inch. Auto via - vias are automatically placed when you switch layers - layer pairs can be assigned by the user. Despite its quality and Blocks = groups of tracks, pads, symbols and text performance, can be block manipulated using repeat, move, BoardMaker 1 only costs £95.00. rotate and mirroring commands. Connectivity £95 Combine this with the 100% buy back can be maintained if required. discount if you upgrade to BoardMaker SMD - full surface mount components and 2 or Board facilities are catered for, including the use of the Router and your investment in Tsien same SMD library symbols on both sides of the products is assured. board. Circles - Arcs and circles up to the maximum board size can be drawn. These can be used to generate rounded track corners. Don't take our word for it. Call us today for a Ground plane support - areas of copper can be FREE demonstration disk and judge for filled to provide a ground plane or large copper yourself. area. This will automatically flow around any existing hacks and pads respecting design rules. Tsien (UK) Limited Output drivers : Cambridge Research Laboratories Dot matrix printer. 181A Huntingdon Road Compensated laser printer. Cambridge CB3 ODJ PostScript output. Tel 0223 277777 Penplotter driver (HPGL or DMPL). Photoplot (Gerber) output. tsien Fax 0223 277747 NC (ASCII Excellon) drill output.

All trade marks acknowledged

CIRCLE NO. 143 ON REPLY CARD

294 ELECTRONICS WORLD+\TIRELESS WORLD April 1991 áe1L Edit S imulatenEllpct Options Pendant: ion - . PROBEREST 455.90 466.33 67 1 -239.66 m -53 .03 3 =38.85

: 0.00 = -0.00 455 .90 461.33

Z 670.34 -4

B 90.00 C -90.00 Learntp Weletetp 1Pólloacp

e1pL F1O-Main menu'

Simulation is an indispensable toolior planning all manner of syseems, and Robotics is no ex.eptior..Vorkspace from Robot S nul¢üons d Nev.ca.tle rune on a K - and allowing engineers to evaluate different robots, experiment with designs 0-factory workcelk or cakilale :ycle tines. Virtual instruments reviewed Real-time PC operating systems OPERATING SYSTEMS

pC use in industry and science has never really managed to match its widespread popularity in the business community, primarily because of the lim- OS -9000: ited availability of a low cost trite real- time operating system. But now a new real-time multi -tasking operating system is available for the 386 PC and single -board computers, combin- real chance for ing many of the individual advantages and benefits of several operating systems in a single modular package. Microware's OS -9000 real-time operat- ing system, modelled on the OS -9 operat- real-time PCs? ing system, brings VME-style, real-time system software to the PC and to the embedded 80386 microprocessor CPU. It will allow the carrying out of more Lack oía real-time OS for the PC has held back industrial than one task at a time - in real-time - and will address the whole 4Gbyte mem- but - ory range as a single contiguous block, application, Microware's Stephen Montgomery says OS giving access to more than 640K without resorting to inelegant techniques such as 9000 will change all that. block switching (OS/2 can also do this - see box). One of the major shortcomings of dos offers the PC user another enhancement har

296 Supplement o Electronics World April 1991 OPERATING SYSTEMS

years. The capability is performed in real- time and is achieved by controlling the execution of tasks with a kernel which implements task switching and interpro- [1.12 A ND'a C119RaRv Cess communication. Execution time is assigned to tasks. in rotund -robin fashion by time -slicing. l alike Microsoft \Vindows. (:I'1' time x - is assigned rather than supervised and so , (-1:rr-,7 SECURITY . tasks do not have to relinquish the CPU of their own volition. In this way true multi -tasking is possible rather than a simple sharing of the processor. Various refinements allow tuning of the execution cycle to weight CPU atten- tion in favour of the most critical and important processes and tasks may not he nun at all if their status is sleeping, sus- pension or wailing. Interprocess communication mecha- nisms provide a powerful and versatile choice of. methods for passing data bow( en processes. whether single bits or large blocks of data (and all the steps bel t'en). and for synchronising the exe- cution of separate tasks. Fundamental to implementation of real-time systems is priority -based pre- emptive task switching (the system E'YOE FINE I designer can designate tasks as high pri- orities that must execute inunerliately they become active. replacing the cur- rently' executing task which loses the remainder of its time slice). 0S-90(11) supports this facility. It also supports a wide range of PC Fig. I. Modular architecture of the OS -9000 operating system hardware and Pe ripheral devices: 1SI)I and SCSI disks and tape. PC floppy disk. graphics. serial and parallel I/O and net- of the I/O manager is required on the tying development ensuring that the working. system. one copy of each file manager for intended version is used. each class of device (disk, tape etc.) and Modularity one device driver for each type of clevice. Graphics under OS -9000 System designers do not always use all A separate device descriptor. contain- Graphics support is available with rave the hardware in a particular project: so ing specific I/O device details, is neces- (real-time audio/ visual environment). a why should they load the fall suite of s ri' for each individual unit. But if a multimedia development tool and user - operating svStent softwarer 0S-9(01) is device driver does not exist for a piece of interface that greatly simplifies design of built of optional modules. each one re- hardware, a new driver can be quickly realistic man/machine interfaces for entrant, so that only one copy is required written in C from scratch or based on an real-time process control systems. It to support a number of similar devices. existing one. combines high quality audio and video, Core of the operating system (Fig. 1.) \n additional feature of the system is computer generated graphics and cus- is the real-time kernel which controls that modules can he installed and tomised menus in the saute user inter- scheduling of tasks and handles ancillary, removed dynamically while the system is face and so allows real -world stimuli to services such as Inenurry management running - an aid to system revision and be itworporateri into a control system. and inner -process communication. testing- perhaps where nt (work calls I he method results in a more intuitive The versatile. unified, hardware inde- can he made to disk for proving. and interface requiring less operator "brain pendent I/O system. able to be cus- then to the actual network. pow( r.. and consequently improving tomised and extended to suit applica- All memory modules. position -inde- accuracy and safety of a system. tion. comprises an 1/O manager. file pendent and run-time locatable. contain Development support contained with- managers and device drivers which pro- a header detailing type of moduli . its in the rave package allows use of cam- cess I () service requt sus al different lev- revision number, and other information. eras. microphone s and 1'C paint pack- els. The system atnontaIicallvchecks the revi- ages at a level easily understood by Because of re-entrance. just one copy sion numbers and uses the la est, sintpli- graphics artists and industrial psycholo-

April 1991 Supplement to Electronics World 297 OPERATING SYSTEMS

Implementation phase can he rates but will simplify implementation of 1''.-_ bypassed since the final solution grows btil-safe and hack -up mechanisms since front the start by addition of new mod- data on the whole system is held locally ules. This, together with the modularity in one machine and can be duplicated requirements of the system. promotes relatively simply. efficient code writing through structured Production data and operating history programming. An additional benefit is is then easily fed to a background that tools can be loaded into any system database for process evaluation. temporarily' for field testing and modifi- A more horizontal application of an cation - extending to rom-based sys- operating system of this type is illustrated tems where even debuggers can he load- by a large point -of-sale terminal manufac- ed for testing the system. turer. Here the application criterion is not so Beyond the PC much for enormous processing capability \Vhile the 386 PC is eminently capable of as commonality of equipment across sev- running the software, it may not be the eral product ranges. Fig.2. Real -lime audio environment (rave) final target. By standardising on one multipurpose operating under OS-9000 on a PC Cost or reliability reasons may dictate operating system, hardware and software transfer of the developed application developments are extended across the onto a stand-alone. custom-clesigned sin- products by a central core of designers gle hoard computer. \t this stage it is a with access to a single library of" code gists. It also releases software engineers straightforward task to port OS -9000 and modules. '\s a result once a device driver, from the task of \l \11 screen design -a the application code onto a suitable cus- for instance. is written it can he used task that can he time-consuming, labori- tom board for final delivery. The main again and again in different circum- ous and unappealing. work required will then he in replacing stances without the duplication of effort the device drivers and descriptors for the that would result if different operating Networking changed hardware and producing the systems had been employed. .\s far as networking goes Ethernet, hoot rom to configure the system at start- based predominantly on the National up (not necessary if the same hardware is The future Semiconductor chipset. is the prince used or the system does not require any So where will OS -9000 be when every- communication medium with TCP/IP peripheral hardware). body has outgrown the 386 and moved serving as the main protocol. on to the 486 and eventually the 586? \s OS-9000 supports this type of network- Applications it is written almost entirely in C. allowing ing with the Internet dedicated file man- Typical applications where real -titre quick porting to new processors the ager which again is installed in a system multi -tasking is required include process answer should he right there with them. only as required. providing a BSI) -1.3 control. industrial control of plants. data Not only that, but if the 386 is not pow- Unix socket-stvle interlace to the TCP/IP logging and communication. measure- erful enough for a particular application, protocols. ment of processes etc.. intelligent prod- code already designed can he transport- ucts such as point -of-sale tt rntinals and ed to another processor with only minor Development environment weighing machines. modification and a recompilation. At OS -9000 provides a complete range of A typical application is where several present this can be toward the 32 -hit rt sident and cross -development tools types of plant monitoring equipment are Motorola 68020. 30 or 40: but will shortly covering languages. C is currently avail- coupled together with a multiple -stage he toward the 88001) risc chip. able. with others planned for future manufacturing process in a complicated Portability provides a highly appealing release and a macro assembler is also machinery/assembly operation. for design option: the operating system can available. Other tools include debuggers example in a paper mill in a classical be selected and application code written for system -state and C source -level rt al -titre application. befine the final choice of processor is debugging; and a screen oriented text Sensors monitor the moisture content, made - and that could he a standard PC editor. tension. thickness and weight of the or a custom single -hoard computer con- 0S-9. the equivalent Motorola based paper as it passes through the wet and taining one of a number of cisc or risc operating system. is supported by several dry processes and cause adjustments to devices. hundred hardware and software prod- be made in process flow speed, pulping With so many advantages over the cur- ucts and this is expected to happen to rate. water addition :utcl drying tempera- rent PC operating systems I believe OS - OS -9000. resulting in an extensive range ture. 9000 is set to become the real-time oper- of packages. Use of a single controller will reduce ating system of the future, and will open \\'ith OS -9000. the operating system the possibility of problems occurring up use of the I'(: to a whole new range of installed to run the application is the between different intelligent machines real-time applications. same as the one used to develop tinder. due to complexity of several separate When developme nt is complete. the sensor/controller processors. tools are stripped off. leaving the bare Basing the whole system on one Editorial survey: use the information operating system together with the appli- machine will not only allow greater opti- card to evaluate this article. Item F cation code. misation to be achieved for production

298 Supplement to Electronics World April 1991 EASY -PC, PCB and SCHEMATIC CAD

For Super Schematics.... BRITISH DESIGN

ket AWARD ,.. . 1989 é - _ .: 04

140 oor.,.--. w, u.le. Runs on:- o --1 i1.- PC/XT/AT/286/386/486 041 trey .010 Vet 044 L. with CGA EGA VGA. ;..

. Design: -

ó Wee, ^^, Single sided, Double ,._ ,fee, I= ' ....,. , .,:, y.. 4.-44 .- ,w...n [.r.,... sided and Multilayer , "r 19:s;es , I IL. boards.

"i11"^ eu1*-+w. 0 r-1 Provides s. 1 Surface .. m e. ...d. ow ._. ,,. ... . _,.^ : -_' L Mount support. Standard output and Perfect PCB's includes Dot Matrix printer, Laser Printer, Pen Plotter, Photo -plotter and N.C. ihr 1 Drill. Superbly EASY to use. a Unlimited Hotline 4 t support. Not copy protected. hay cliiisrd tc. Over 7000 ape omai installations in go II over 50 Countries worldwide. Over 500 . installations in Universities, Use Award Winning EASY -PC Colleges etc. NEW VERSION - LASER PRINTER SUPPORT!

Write,'Phone or Fax for full details: - See us at CAD -CAM, Stand 201 Number One Systems Ltd. I REF: WW, HARDING WAY, ST.IVES, HUNTINGDON, CAMBS, ENGLAND, PE17 4WR. Telephone: 0480 61778 (7 lines) Fax: 0480 494042 International: +44 480 61778 / 494042 ACCESS, AMEX, MASTERCARD, VISA Welcome.

CIRCLE NO. 104 ON REPLY CARD

April 1991 ELECTRONICS WORLD+WIRELESS WORLD 299 PC REVIEW

Simulating the system

Maxsim is designed to model and analyse the performance of systems in frequency and time domains. John Anderson tries it out and explains his reservations

Rilaxsim is a simulation system provid- Maxsim is written in Turbo Pascal with Ming performance analysis in both the auto screen -sensing facility, allowing it to frequency and time domains. The mod- be used with a number of popular screen elling system relies on describing the for- standards. mat of the various system blocks in a sim- ple Ascii file, which is then interpreted, Entry of the transfer function checked and simulated. Typing Maxsim executes the program. After the sign -on message, you can select Program installation the file to be simulated from the files Software is supplied on a single disk, with the extension .DAT. Once the file together with a thick, spiral -hound, pho- has been selected, the program moves to tocopied manual. The software compris- a simple Ascii editor to give you the es the single application file, a number chance to set up the system for simula- of example files and a few graphics files. tion. An example is shown in the box. An install file copies the program to your When the system file has been set up, hard disk, though you could do this your- the program checks the formulation for self; there is no copy protection. Rather errors of syntax. There may be some strangely, the latest version of Maxsim errors which cannot be detected until insists that the program should reside in the system calculation routine, which a different directory to the data files so, if may then cause the program to abort. Bode plot for 8th order you copy the files across yourself, follow Chebychev low-pass filter. the instructions carefully. Frequency simulation In the frequency domain, magnitude and phase information is derived from

O -~ either automatic or user -defined fre- -s . quency range and increment. This pro- -lo -15 cess was quite slow, taking several sec- -20 onds to the data set a dR produce on 8M1 Is -25 AT. Once generated, the data may he dis- -30 as - 35 played any one of the Bode, Nyquist, I -4o inverse Nyquist or Nichols charts. As all 2 3 4 5 6 7 8 9 2 3 4 5 6 7 8 9 the data is available at this stage, screen 1OnHz lOOnHz 1Hz plotting is fast. AMPLITUDE RESPONSE of node 6 Time simulation A reduced subset of the built-in compo- nents may be simulated in the time domain. Why capacitors and inductors 1 so loo - are excluded from this is not clear, since 50 it obviously limits the use of the package o = when compared to other performance deg -50- simulators such as Spice. Time simula- -100- tion follows same -15a the procedure as for the frequency simulation, the steps of 2 3 4 5 6 7 8 9 4 5 6 7891 the time simulation slowly accumulating 1OnHz 100nHz 1Hz until the dataset is complete, at which

300 Supplement to Electronics World April 1991 PC REVIEW

SIMULATION MODELS 1.4 -

1.2 - General system models Integrator, simple gain, adder, second - order phase shifter, sampler, pure time phase delay, multiplier, divider, shift. 0.8 - In time domain Limit, backlash, friction, dead zone, 0.6 - noise generator, digital filter, stiction, switch. 0.4 - In frequency domain Resistors, capacitors, inductors, voltage 0.2 - amplifiers, mutual conductance, line, operational transformer, delay 0..0 amplifier, transistor, fet. r, r,TrT Stimuli O 10 20 30 40 50 60 70 80 90 100 Frequency: frequency sweep, linear, log or spot frequencies. Time: step, ramp, square, triangle Secs and sine wave, or from a user- specified 50 -point curve. Output of node 6

TIME RESPONSE of data file ZFILTER.DAT 21 -JAN -1991 20:03 point it may be plotted. An interesting option is to he able to Time response for 8th order Chebychev 19w -pass filter. set the type of numerical integration used in the simulation, from rectangular L and trapezoidal to a fourth -order Adams MAESIM EDIT PROGRAM SERVO.DAT Insert mode On Bashforth. It is not clear why an engineer Edit File: would want to do this, but it could prove SERVO.DAT - Example of hydraulic valve - 2nd order system Al useful in the teaching environment, a.361850íá li 93 where the sensitivity of the various algo- P1 6, 1,12E-3,0 1,1,2E-3,0 END OF SERVO.DAT rithms to step length could be conve- 2nd ordºo system with I?ad-lag compensation niently demonstrated. o A wile range of input stimuli is avail- able for the time -domain simulation, including step, pulse, ramp, sine, trian- IRow C,I File Length F1 F2 (F10+ F5 F6 insLInsee Helg Exit (Save) ,.DAT ..INF. To 1 ~ gle and user -defined functions, defined by data. In the time domain, the input editing environment driving function can be defined by the user in a file arranged as a table of up to facility within the editor was rather better 50 values, stored as two columns. The and included examples of data file layout Using Maxsim first values are the increasing titile sam- and syntax. However, there was a bug in The program can handle systems of up ples and the second values are the corre- the program which prevented invoking to 50 nodes per sub -system and of up to sponding function amplitudes. the help system within the editor a sec- 50 sub -systems per node. As the program ond time. was rather slow even with the modest sys- Examples and help tems provided in the demonstration set, Examples of electronic, mechanical and HARDWARE NEEDS it is likely that large systems at the limit multi -loop control systems are presented of what can he handled with this pro- to give a sound base for simulating your gram will take many hours to run. own system. The help system, although Minimum is a PC or PC -AT run- Once the rather strange user interface context sensitive, is very limited and gives ning MS-DOS version 3.0 or later. was mastered, the generation and testing little assistance. An indication of this is CGA, EGA, VGA or Hercules of complicated systems was accomplished that the route out of the program is not graphics card. in short order. However, there were a properly sign -posted. It turned out that, Optional Epson -compatible printer, number of occasions where the data pro- at one particular level, the user must HP plotter or HP -compatible laser vided to the program by this novice user press the "Q" key, which is fine once you printer. - was not wholly sensible, and the program know, but the exit from any program handled this in the worst possible way by should be a simple matter. The help printing an error number and returning

April 1991 Supplement to Electronics World 301 PC REVIEW

SUPPLIER

Maxsim System Simulation for the PC costs £425 excluding vat for a single copy. Adrian Morris Engineering Ltd, 60 Southway, Totteridge, London

-0.2 - -0.4 - lag compensation and I'll) (proportional -0.6 - integral derivative) control. Other topics -0.a - are non-linear systems and state feed- back. 1 , In simulating complex. non-linear. -0.5 real -world systems, many of the niceties of linear analysis are lost and the only way to ascertain the performance of the system is by simulation. However. this NYOUIST PLOT of data file SERVO.DAT of node 6 alone is not enough ill that it does not determine the sensitivity of the system to Nyquisf diagram for a second -order servo the various gains. phase shifts and non- linear attributes. 'knottier related aspect

to the operating system. An example of printer, I IP plotter or HI' -compatible of some non-linear feedback systems is a this operation is that the program aborts laser printer. Both time and frequency mode of operation called jump reso- if less than three spot frequencies are graphs can be expanded using a zoom nance, where the frequency response entered. There can be little excuse for facility to show specific items in more depends on the direction of the input this bad behaviour from a computer pro- detail. It is only possible to show one sweep and the input amplitude. Maxsim gram. particularly one which has reached graph on the screen at a time (an excep- only offers increasing frequencies. version 3. The manufacturer is well tion is a Bode magnitude/phase plot). so aware of these deficiencies and is work- performance comparisons at the various Conclusions ing to improve matters. nodes of the system mast he done with \laxsint has the feel of a rather amateur the plotted results. product with a number of rough edges. Plotting Its main abilities are in frequency Graphical 0111/)111 of frequency and tune Manual response analysis and to some extent the response is available from any node in Although produced on a low budget., the time domain, the reasons for its low level the system, which might be particularly manual is well written and very compre- of interest in the time domain being' his- useful if you are investigating possible hensive. It not only covers the operation torical", according to the maker. Its slow saturation effects of antplifiei s or devices of the program, but also provides an performance and limited features make inside a complex series of feedback introduction to control engineering as it seen[ poor value for money. loops. Built-in drivers enable the plots to well as some worked examples. which Its redeeming feature is that it can be presented on an Epson -compatible start with simple concepts such as lead- tackle very complex multi -loop systems which competing products cannot han- EXAMPLE dle. The system descriptor file uses a sim- ple format which, in principle. could As an example, an 8th -order low-pass Chehychev filter with a 2dB ripple in the even he generated from a circuit net list. pass band. It is made up of four 2nd -order sections, each as below. The transfer Used in this way. Maxsim starts to look

function for the first block is Pl . For the first block, G = 1/(0.565 + 0.266s + s2). like a circuit simulation package such as This polynomial fraction is represented in Maxsim simply as a phase shifter block: Spice, but its limited libran' of electronic components and inability to handle time

PI 1,2, 1,0,0, 0.0565, 0.266, 1 domain rt spouse for discrete compo- nents limits its usefulness for the elec-

The interpretation of this syntax is: nodes 1 and 2, numerator coefficients for tronics engineer. Its real forte is highly s0, st and s2 orders, and three further coefficients for the second -order polynomi- complex multi -loop non-linear systems. al in s in the denominator. The remaining three blocks are defined ill a similar although with systems of this complexity manner, ending in a normalising gain block. Bandwidth is lrad/s. beware the Onset of -mathematical prob- Combining this with the further blocks shown below gives the complete 8th - lems such as chaos and the deviation of order filter. real and simulated performance due to finite number length representation. P2 2,3, 1,0,0, 0.3271,0.225,1 The cost of £-125 is rather steel) for a P3 3,4, 1,0.0, 0.7098,0.150,1 product with this limited specification. P4 4,5, 1,0,0, 0.9804,0.052,1 but then there are not many multi -loop K1 5,6, 0.01286 simulators to choose front!

Since the blocks are general system blocks, simulation can be performed in the rime as well as the frequency domain. Not surprisingly, the time response of this system for a step input shows a considerable overshoot. Editorial survey: use the information card to evaluate this article. Item G

302 Supplement to Electronics \\ orló April 1991 DUADRATURE ECA- L DSC ILL 4104 FAST, FRIENDLY, FLEXIBLE FEATURES ECA-2 is a powerful user-friendly program for ¢ analogue circuit analysis. In association with a spe- Á7.S. daily tailored graphics entry program, you a- can draw and analyse your circuits simultaneously. 16IGINFIGiFi Even with just its L+ea- some of features that we have been able to show in this ad, you will be pleasant. ,I ,...,a, "' "` dial IYdIIJf'dL li'i1Ifllli1Li11 E" ly surprised by its pricing. Shown below is e WA iYN11111111111'111111 a small corner of its facilities. To see more, you must 6' ,,,1fe l Ilila , 02 3 contact for B 1QlQnW01Í us a free demo disk which is the complete program limited only in the size of circuits it ,- }-} can handle. The full version is able to handle upwards of 500 circuit nodes! °ád2 VVe"' 0Marla .i !i I we : 154

43 v-

e.. "'II' Ur, 1i° r?. Components

I Transient Analysis This calculates circuit conditions over the prescnbed time range at the pre- xx .I ECA-2 accepts simple twoterminal linear components such scnbed intervas. This is a full nonlinear analyse which is illustrated here by a quadrature oscillator. The cir- as resistors it curt generates two sine waves in quadrature. A :mall initiating pulse is required and is - - and capacitors: includes current and voltageg produced by the pulse generator whose 1,,,¡` xxx sources and transmission lines. Diodes are described by the output resistance is made very large so that it has no effect on the subsequent operation. n 0- exponential diode equation wherein (amongst other parame- ECA-2 allows up to four points tobe plotted and here the quadrature waveforms and the current in RS are

r F) ters) the user can define the emission coefficient, energy gap, x ( temperature correction factor, and loardrw and reverse resis- Lances. This real xx /, i '' I # enables diode characteristics to be ....,, , .,, , , , . .., .-. a... ,. ,, ro. .--(.=-18 matched. Transistors, thyristors and DC Signal 1 operational amplifiers . "p' Analysis can also be modelled. These can be saved as macro models and a number popular is zzvl 1 of devices supplied on the disk. = , - Here the analysis is carded out at a fixed temperature with Furthermore, non-linear functions -T }-axx can be added to any win- L the signal generators set to dc. An interesting app 'cation of

ponent to enable for example zener diodes and voltage. I r this is the Schmitt Trigger where the dc command is used to x It , tE.' xx variable capacitors to be created. is possible to define com. _ -.E::,,-1.- - step the input from -5V to 5V in 0.1V steps. The loop option ` xxx ponents in terms of their real and imaginary parts, for exam then causes the voltage to reverse so that the hysteresis loop pie to deli e the band -width or phase shift. - --" i I can be traced. In conjunction with the sweep command, this -r allows the effect of altering the resistor At from 5 kt1 to 30

;. i J } I k>2 in three logarithmically spaced steps to be observed.

Statistical Analysis - 1.1 ,a .. If your work involves designing, developing or verifying analogue or digital circuits, you will wonder how you ever managed without Those A rather pessimistic worst case analysis can be " o : trill; Engineers circuit run. It also performs a sensitivity analysis indicating Simulation Software.

which tolerance contribution is the most important - - , ------ii, t factor, whilst Rc2 has negligible , A good range properly effect. A more realistic esti- i i 1 u' "011 ,,,,I of supported and proven programs is available

mate u ' i Hl of production yield is obtained by a Monte Carlo analy- " ( ii'I and our expert staff are at your service.

which 11 sis can be tabulated or displayed as a graph. Just 25 i i' 1 ' ' ' l runs of a 3rd order Chebyshev filter are shown here. _ - Telephone: Charles Clarke on 071-435 2771 for a demonstration disk. 0 106a Fortune Green Road West Hampstead London NW6 10.5 LUM0 _° LTD c/G n 1491 Tel: 071-435 2771 Fax: 071-435 3757

CIRCLE NO. 105 ON REPLY CARD

SPECIAL Prices are correct at time of press but may fluctuate. VALVES QUALITY Please phone for firm quotation.V.A.T. included. A1065 240 EF37A 2,45 PFL209 2.80 Z800U 3.45 6CL6 2.75 12A18 1.95 A 140 PL36 1.60 2801U 3.75 740 12A17 two year guarantee A2293 7.00 EF39 6C334 125 A2900 12.75 EF80 0.65 PL8r 1.30 Z803U 21.15 6058 4.60 12AU7 0.95 AR8 1.40 EF83 390 PL82 0.70 Z9001 9.50 6CV5 1.15 12AX7 1.50 ARP3 145 EFBS 0.90 PL83 0.70 IA3 190 606 2.50 12BA6 2.95 on all our second-hand ARP35 1.50 EF86 1.45 PL84 0.90 1L4 0.95 6F6G 2.90 128E6 2.40 ATP4 090 EF89 1.60 PL504 1.25 IRS 120 6F608 2.90 128H7A 536 0120 6.90 EF91 1.60 P1.508 2.00 154 120 6F7 2.80 12E1 19.95 CV31 2.40 EF92 2.15 P1509 535 155 0.85 6F8G 1.75 12.1501 1.80 Test Measurement DAF70 1.75 EF95 140 PL519 585 114 0.75 6F12 1.60 1207G1 1.15 and DAF96 1.35 EF96 0.65 PL802 660 IU4 125 6F14 1.15 120801 125 DET22 32.80 EF103 0.75 PYBO 0.90 2X2A 380 6F15 340 1207GT 1.15 DF92 0.95 EF184 0.75 PV81 0.75 344 1.30 6F17 310 12SH7 125 DF96 1.15 EF812 0.75 PV811800 085 34.12 3.40 6F23 0.75 17537 1.40 equipment! DH76 1.15 EF1.200 185 PV82 0.75 3828 17.50 6F24 1.15 12507 1.45 DL92 1.70 EH90 0 85 PV88 0.60 306 1.15 6F33 10.50 1250701 2.20 008687 065 EL32 085 PYSOOA 2.10 3E29 21.85 6FH8 18.80 12Y4 0.70 To give you the confidence that you really did 0Y802 0.70 EL34 325 00003/10 595 354 1.70 6GA8 0.65 1303 2.80 E92CC 1.95 EL34 9.50 00003/10 7.50 4832 35.00 6GH8A 1.95 1306 0.90 save money by buying second-hand, we are the E180CC 980 EL82 0.70 00003/20.4 5R4GV 4.85 6146 1.60 19A05 185 61148 0.75 EL84 1.35 27.50 5U4G 1.85 6J4 195 1903 11.50 only company to offer you the protection of a two EA76 1 on EL86 1.45 001/06/40A 5V4G 190 6141NA 3.10 1906 10.35 EB34 1.15 EL90 1.75 2850 53301 3.45 6.15 2.30 1985 38.00 labour guarantee on all the EB91 060 EL91 6.50 00V06/40A 523 4.85 6.1601 180 2001 0.80 year parts and EBC33 220 EL95 1.80 46.00 5240 2.20 636 2.20 20E1 1.30 we EBC90 1.20 E1504 2.30 0003/12 7.40 530L2 080 6.16W 280 20P1 060 Test and Measurement equipment supply. EBC91 1.15 EL519 7.70 004.400 101.60 6AB7 1.85 61E6C 9.15 251607 190 EBF80 0.75 01.821 7.50 SP61 320 6AC7 1.80 6JS6C 9.15 25ZAG 1 80 EBF89 0.80 E1822 11.50 18205/409 88.30 6AG5 060 6J116 6.35 8542 1.40 Dealing in equipment from the leading EC52 0.65 Et LOOSE 4.50 1721 47.50 6405 1.90 607 220 85A2 255 EC91 5.20 EM80 1.50 TT22 45.00 6AB 2.85 6006 13.75 5728 50 35 manufacturers such as I lewlett Packard, EC92 5.55 EM87 2.85 T3/-125A 85.30 64.15 0.60 616 780 807 3.45 ECCOI 125 EV51 0.90 TV 400A 9420 6AL5W 1.50 616GC 9.60 807" 4.30 7éktronix, Marconi, Philips, Gould, etc., we can ECC82 0.95 EV81 1.10 UABC80 0.75 6AM5 6.50 616GT/C 2.90 81.1Á 1350 ECC83 1.50 EV135/87 0.75 UBF80 0.95 6AM6 1.60 6118 0.70 812A 32.00 offer you the hest in test. Call us now for ECC84 0.60 EV88 0.65 UBF89 0.95 6AN8A 3.80 61020 0.70 813 2850 ECC85 0.75 EZ80 0.80 UCC84 0.85 5405 1.75 6106 9.15 813 44.00 more information. ECCBB 125 EZ81 0.80 UCC85 0.70 64.05W 2.90 6070 1.50 8298 1600 ECC189 1.20 GM4 11.05 UCH42 4.60 6456 1.15 65A7 1.80 8798 2400 ECC804 0.65 GN4 6 30 UCH81 0.75 54570 4.95 6507 1 80 866E 14.95 ECF80 1.25 GV501 1.50 UCL82 1.60 6ÁU6 0.90 6537 2.50 931A 1895 ECF82 1.60 GZ32 2.80 UF41 1.85 640401 1.30 6507 185 931A 2880 ` ECF802 1.00 0733 420 UF80 1.60 6AX5GT 1.30 6517GT 435 954 1.10 ECF804 4.50 0734 2.80 UF85 1.45 66A6 1.75 65N7GT 4.35 955 1.10 ECH35 2.75 GZ37 3.95 U184 1.50 6BA6 2.20 6507 3.20 956 120 ECH42 1.65 KT77" 16.10 UM80 230 6BE6 1.75 0007 4.60 6060 1.95 / . ECH81 175 MX120/01 29.50 UM64 1.30 68E6. 220 6V601V 1.50 6080 7.30 ECH84 0.90 N78 9.90 UV82 1.10 68060 2.65 604 1.50 6136 280 ECI80 0.75 082 1.70 0V85 0.85 6836 1.75 60501 0.75 61468 10.50 ECL82 0.95 P01.87 0.95 VR10530 2.75 66074. 395 6Y6G 280 6336A 33.35 ECL85 0.95 PCL84 0.85 VR/50/30 2.75 6887 4.80 624 1.75 9001 1.40 EC186' 120 PC186 0.80 066 4.95 6BW6 6.10 72.6 1.90 9002 6.50 ECLLB00 17.50 PCL805/85 0.95 011210 11.50 6BW7 1.50 906 2.15 9003 850 `/ EF9 300 P0500/510 5.60 2749 0.75 6C4 120 11E2 19.50 CAPELLA EF22 3.90 PF1200 1.10 2758 17.90 6CH6 750 12A6 3.50

TECHNOS VALVES AND TRANSISTORS NEW HEADSETS mi.,o a -m microphones CAROL 1111339M at 610.00 FIELD TELEPHONE, CABLE TYPRE DIO Headphone imp 4.16 ohms. Microphone imp at 600 ohms HELD TELEPHONES TYPE 'J'. Tropical, in metal ca. .es. E-80 et 615.00 10 -ulna MAGNETO SWITCH-BOARD. Can work with Headphone imp 416 ohms. Microphone imp at 200 0800 521231 every type of magneto telephones. ohms. Surplus VIDICON P8211 and others at C18.00. International Callers No. 44 344 869 226 POSTAGE AND PACKING CHARGES: 61 -(3 (1. E3-05 (1.20 (5-610 (Lao. 01015 (1.70. (15.70 62.50. over 020 C165 Pamela over 21(g at Cost Capella-Technos, Park House, The Pavilions, Irownmill Road. Bracknell, Berkshire, RGI2 1QS. Fax 0344 869230 - nA COLOMOR (ELECTRONICS LTD.) 170 Goldhawk Rd, London W12 Tel: 081-743 0899 Fax: 081-749 3834. Open Monday to Friday 9 a.m-5.30 p.m.

CIRCLE NO. 106 ON REPLY CARD CIRCLE NO. 107 ON REPLY CARD

April 1991 ELECTRONICS WORLD+ WIRELESS WORLD 303 PC REVIEW

Voltage and ;. -.:.., .. current on screen

Blue Chip Technology's intelligent 1)illlll is one of the new breed o/ virtual instruments /o the PC, offering voltage and nil rent measurement, char recording and data logging. Mike Toolev has been using it for some time and presents Iris com- ments

Avirttual instrument is simply the emu- rent and resistance. but will store these lation ofa conventional piece ()I' lest values for later analysis a cl export to equipment basecl on a microcomputer software packages such as Loins 1-2-3. system lifted with an appropriate expan- Fttrtherntore, virtual instruments may he sion cardd which. in turn. is driven by suit- n adil programmed so that they can able software. Such combinations otter fibrin the basis of automatic test equip- an increasingly' cost-ellectiye solution to ment systems. the use of traditional stand-alone items Extremely useful: Blue Chip's DMM hoard of test gear. Cost effectiveness provides the major fiu,cliorrs c f a ?millimeter At first sight. the concept of virtual A conventional intelligent digital multi - with the data loggingfacilities ofa data instrument display may appear to he meter such as the Fluke 8840r\. or acquisition system. something of a gimmick. Attempting to Keithh v 197 will set you back between Good psychology: most people assimilate emulate the front panel of a convention- £500 and £750. \dd to this basic price analogue readouts faster than the digital al item of test equipment on the uto- an extra £151) to £200 for an IEEE 4S8 equivalaent. This virtual instrument dimensional screen ofa P(; is. after all. "option" and you have a sizeable outlay. provides both. something of at artificial exercise when Furthermore, when you purchase such one realises that none of the usual manu- an instrument you pay for a case. a poser ally operated controls is available! Of supply. a front panel fitted with controls course. mouse control adds another (if and displays. one or more printed circuit at times cumbersome!) distension to this hoards. the labour to put it all together, and at least it provides the user with a overheads incurred with development, means of pointing to. a cl clicking on. marketing and (lis ribttion. the required function. Remember. however. that you already Behind this is the reasoning that an have a case. display and power supply engineer is much more at home with already siting on your bench in the form something that he recognises as part of Of your P(;. With a virtual instrument the usual range of workbench test equip product. therefore, the first three items 3 _ mein. Tell hint that you will exchange a are no longer required: in wit( r words. a . .: PC such stalwart items as a I)V\I. greater proportion of' your cash can be - fi- ..... oscilloscope or chart recorder and you directed towards the functionality of the J' are likely to be given a pretty

301 Supplement to Electronics World April 1991 PC REVIEW

a full-sized 8-bit bus PC expansion cant, lion, which compares favourably with all which employs a mixture of surface - but the more expensive of conventional CPERATING ENVIRONMENT mounted and standard technology. "[he bench instruments. It measures direct card is fitted with two standard fnun and alternating voltage (each in four DLIM-VIP requires an IBM- banana sockets (fbr signal input) on the ranges from 200111\' full-scale to 30(1V PC/XT/AT/386 (or compatible) with industry -standard 0.75in pitch, together full-scale), direct and alternating current one 8 -bit bus slot free and a standard with a male 9 -way 1) -type connector for (each in three ranges from 20ntA 6111 - mouse. A minimum of 640K of ram is control of an optional external scanner. scale to 2A full-scale), resistance (in needed, together with EGA or VGA Board layout is uncluttered and. in many seven ranges from 20(2), capacitance (in graphics (either colour or cases, users will not need to change the four ranges front 24' to 2µF in four monochrome). settings of the configuration jumpers fit- ranges) and (Ulm. Accuracy of the ted. direct -voltage ranges is between ± 0.02% and ± 0.09% of reatlíng, while in AC Chart recording and data logging ranges it lies between ±0.5% and ±1% of followed, the user should be presented One of the outstanding advantages of reading. AC ranges provide true-R\1S with a fully functional front -panel display the 1)\I\l is that it incorporates a chart indications and the input is rated at in minutes. recorder display, which closely emulates 100\'DC/ 100\' peak \C maximum. Programming the I)\l\I-VIP is very a conventional chart recorder, with mov- Accuracy on the resistance ranges easy, thanks to the driver sofis are provid- ing "chart" and "pen". Chart speed varies from ±11.06% on the the ee lowest ed with the package. The technician or (sampling rate) is adjustable to a maxi- ranges to 1% on the 20\112 range. Ott engineer with only a modicum of solt- mum of 25 samples per second. capacitance, accuracy is ±2% to ±5%. ware knowledge will he able to control The data logging function, which is Instrument display provides 4.5 digits the instrument from packages such as available when the chart recorder display and count headroom before overrangt \licrosoft Quick&\SIC or C. is selected, allows the user to log the indication is generated amounts to acquired data in a named disk file, data 29,00( counts. Operation tieing stored in standard comma -delimit- Base addtess of the instrument is D\I:+I-\'II' has been in regular use in my ed Iorunat which is compatible with most selectable within the I'C 1/O Wrap workshop over the last two months, software packages such as Lours 1-2-3 between 20hex and 3F.Ohex -a total of installed in it DS(: "Turbo AT -compatible and Won1star. On completion of mea- six addresses within the I/O map is fitted with 1 \lbyte ram, Microsoft bus surements, data may lw replayed by the required. The instrument may be config- mouse and EG \ colour display. During chart recorder display, analysed by other ured to interrupt levels of between IRQ2 that time, I have used the unit in a vari- packages (a spreadsheet, for example) or and IR(17. ety of tasks. ranging from the purely dumped to a line printer in chart - nnntdane to the abstruse. I wits able suc- recorder format. Documentation cessfully to "automate" a number of mea- If single-channel operation is not The MINI -VIP is provided wtith a 78- surements of RI' transistor parameters acceptable. an external scanning unit. is page. A5-format. spiral -bound handbook, (with data logged and exported to a pop- available to increase the capacity of the which describes installation and applica- ular public domain spreadsht et). I also basic D\IM, chart recorder and data log- tion of the chart recorder and 1)\h\1, found the chart -recorder facility useful ger to a maximum of 32 channels per seven appendices providing reference when observing the tent pet attire rise instrument. Each channel of the DM \I (lata on clocks and timing, I O address- within a complex heat. -sink used with a can be set up for a different Itrttction and es, interrupt levels and calibration. It is prototype power amplifier -a ask range. laid out in a logical manner and will be tthich would otherwise have required the of value to the newcomer to virtual manual plotting of a graph. Specification instruments as well as providing more For many of the mundane nteasure- D\t\I-\'11' offers an impressive specilica- specific details on measuring techniques. ntents, however, I muss admit to being Sections are included for "experienced tempted (at least initially) o return to users" and the handbook also includes a my bench 1)\lNl, even though the was to he SUPPLIER "(~nick Stat I Guide" for people who may mouse/screen interface found the up and somewhat more workable than I was orig- DMM-VIP is available from Blue Chip be in a hurry to get system to give it credit for. Technology, Hawarden Industrial running. inally prepared Park, Manor Lane, Deeside, Clwyd Conclusion CH5 3PP. Phone 0244 520222; fax Installation and programming to The Blue Chip Technology' D\1s1-VII' 0244 531043; Telex 61471. The hoard is factory configured an I/O base address of 03(1011ex, interrupt offers a full range of I)NINI specifications in :t package which cannot be faulted for The package costs £495 (excluding request level 3 and internal clock. versatility. It must surely represent out- vat) and the optional sequential Default values in the setup software is standing value at less than £501). scanner costs £149 for each group of match these settings; all that required eight channels (subject to a of the user is to press the RE [URN key maximum of £32). in response to the setup questions. Fitting the board and installing the soft- ware is thet('fure simplicity itself and, Editorial survey: use the information provided the 11w basic instructions are card to evaluate this article, Item H

April 1991 Supplement to Electronics \Vorld 305 AN RF SPECTRUM ANALYSER FOR ONLY £345? (+VAT) The 107 SPECTRUM PROBE converts a standard ,í 1 MHz scope into a 100MHz spectrum analyser. 70dB dynamic range 40dB spurious rejection 50µV sensitivity, +/-2dB flatness 1 kV DC, 1 v/+ 15dBm @ 100MHz Max signal ±5% frequency axis linearity APPLICATIONS RF Radiation. When used with a short antenna, the local RF field can be monitored. Check for emission from computers, switching PSU's etc. Servicing. The low capacity input of the Spectrum ,P-..- 3-q.416 Probe allows circuit probing without affecting circuit operation, allowing rapid evaluation of performance and problems. 1 w-..- .. Mains -borne RF. The high voltage input rating of the Spectrum Probe allows direct measurement of RF noise. Signal lines and ground lines can equally be checked.

Education. This low-cost, easy -to -use probe is ideal for teaching RF techniques and the frequency P domain. - n Available only from Laplace Instruments Ltd at £345 plus VAT (£396.75) including mains LAPLACE INSTRUMENTS LTD adaptor, manual, equipment case, BNC adaptor and postage. Full Masters House, Bexton Road, Knutsford, unconditional refund if returned within 15 days Cheshire WA16 OBU. Tel: 0565 50268 undamaged.

CIRCLE NO. 114 ON REPLY CARD

PLOT THE DIFFERENCE PLOTVIEW

Is the simple, low cost alternative to PLOTVIEW allows paperless plotting and paper plots. Able to preview plot images replotting - avoiding delays, improving on a graphics screen within seconds, efficiency. PLOTVIEW

Has up to 25 separate plot files Easy to integrate, PLOTVIEW previewable simultaneously on screen is ideal for system builders and can and a zoom function which allows any be Customised to suit their part of the plot to be Inspected in detail. individual needs. Digital Phone now for more details about PLOTVIEW: IEEE488, I/O, Timer the versatile tool that can really make a difference Counters, RS232, RS422, to your productivity. RS485, D/A, A/D, Acquisition, Analysis RVICES LTD. AND A WHOLE LOT MORE! Brain Boxes, Unit 3G, Tel: 051-2207190 Telephone OXFORD (0865) 512678 Wavertree Technology Park, Liverpool. & 051-220 2500

CIRCLE NO. 115 REPLY CARD ON CIRCLE NO. 116 ON REPLY CARD PC REVIEW

PCL-860: D performance 1 on a PC

How well does the PCL-860 4. 5 digit voltmeter PC expansion card measure up? Allen Brown plugs in to find out.

Explosive growth in expansion cards by thing a four wire arrangement where for the PC means that now the elec- two of the wires provide a current source. tronics engineer can quite easily have a Minimum resistance range is 2052 (res- machine dedicated to data acquisition olution In112) and the maximum is a and measurement: drop in the appropri- rather limited 20k12 (resolution I12). ate card and the I'(. is transformed into a As with the majority of expansion logic analyser, a digital 'scope or a host cards, the PCL-860 has a switch setting to of other devices. allow users to choose their own l'C I/O One such card is the PCL-860 l)V\1 address with appropriate wait states to from Fairchild -a full length expansion enable the card to he used with high card presiding a facility for measuring sptriid PCs. It has a lb-bit A -to -1) convert- voltage and resistance. er and a bandwidth of 10k1 -1z. Four voltage ranges span 200\' (resolu- tion 10niV) to 200ní\' (resolution 10µV) Installation Fig. I. PCL-860 pop-up display within a for both 1)C and \C inputs with an accu- Installation of the card is very straight IVindows environment. racy of±0.(10 3%. Resistance is measured forward, though it is advisable to insert the banana plugs in the card's bracket sockets first. They are a very tight fit and resulted in the bracket bending when ,IS -DOS Erb, the card was in place. =]Select Windowed Comwnd Process file Viet, Special (- PCL-860 DIM [he P(:1 -860's own device driver (installed in the PC's (;ONFIC.SYS file) A 0©I D r- f E1-1 C PIE CUTPRINT.EXE PIFED allows a pop-up display to he evoked by 200U - 11, 5. 5 DuC , PRRCT { R4TRRV.TXT DOTHIS.TXT pressing the two shift keys. An attractive ARC .TNT DSP.4lRI PSCRI - display panel (Fig. I.) shows the device RPPLETLK.DLL ECR40.FON RE ADM BARRY .TNT ECRBU.FON RERDN settings and four function boxes activat- j PRESS SHIFT -SHIFT TO TURN OFF DUN. BARRY .URI EPSON9.DRU RERDIII ed by cursor keys. CRLC.EXE FRED1 .4Rí I REUER' Function boxes offer the various CALENDAR .ENE FRED2.UR1 ROHR i GARDE ILE.ENE HDS.4IRI SCRIP option setting on the card, for example CCR40.FON HDS2.tIR1 SPOOLER .EXE ACV or l)(:V and display rate - display CCRBO.FON HELUC.FON TEMP .TRII is accessing the CHIRP -1 .11SP HELUD.FON ERN.TXT rate adjusted by FU\C. CLIPBRD.ENE HELUE.FON TERIIINRL.EXF box and has a maximum value of 10/s. CLOCK .EXE HERCULES.FON fEST.tIRN But in these days of multitasking front CONtIRNDE. P IF H1IEN.SYS TESTCRRD.CRD CONIIRNDF.PIF LOO.TXT TIIIF.1ISP ends, the PCI.-860 requires a dedicated C04111RNDU.PIF NENSET.EXE TIISRC.FON doswindov% (CO\I\1:\\I).EXE) which CONTROL .ENE NODERN.FON TIISRD.FON can take up a lot of memory. An example COURC .FON NSDOS.EXE TIISRE .FON COURD.FON NOTEPRD.EXE t11N.INI (shown in Fig. I.) is where the host mul- COURE.FON PRINT.EXE HIN.OLD titasking environment is Windows/386. For British keyboards. the I'C1:86() requires a terminate and stay resident (TSR) routine which must he evoked once envy into the command window has been made. But the I)V\1 becomes

April 1991 Supplement to Electronics World 301 PC REVIEW

into once entry the command window PCL-860 data Reservations has been made. But the DVM becomes My reservations on the PCL-860 focus on inactive when the window is put into four aspects; I must question whether a background mode, which is a little IBM XT/AT or 386 16-bit A -to -E) converter is adequate for a disappointing. Dos 3.x DVM. I also do not like the way Adding to its functionality, the I'CI.- Colour or monochrome moni-or resistance is measured using two wires 860 can be driven from a number of Supplier: Fairchild Ltd, Eastpoint, for a current source. If lead resistance high-level languages and Fairchild Burgoyne Road, Southamptcn SC2 6PB. needs to be considered, then four wires provides sample programs written in C, Tel 042121-6527. £349 plus +/AT. are necessary (there is no reference to Basic and Pascal. lead resistance in the manual). A set of command instructions allows There is no option for measuring the user to configure the card and current, which is a standard feature on control its operation from within a understanding operation of the P(1.-860 most DVMs. Lastly, at £350 the board is program, and the extensive C sample from a programmer's perspective. not cheap. programs give a good insight into the Chapter six covers calibration But putting my reservations aside, the programming possibilities hell out by procedures, effected by using a product performs well within the the PCL-860. calibration software routine and specifications laid out in the manual and Data can be imported from the card manually adjusting the board's if a user has a requirement for a PG and further processed or stored on disk potentiometers. The method is not based DVM with these specifications, for future analysis. particularly appealing since auto - then the PCL-860 is a product worth A standard set of leads and calibration procedures have been considering. terminators is provided and the around for several years now. accompanying manual is quite well Editorial survey: use the information written with many diagrams to assist card to evaluate this article. Item I.

. "f,» , -1_1.0111P. VI. One phone call brings the .WORLD to your door.

If you have trouble finding us in your newsagent, why not '_ consider a subscription? One phone call to Lindsey Gardner will bring Electronics World delivered directly to your home. in ELECTRONICS re fn WORLD The cost? Just £20 for 12 issues. 9 27tsswaw The magazine arrives in a protective sleeve and should ui arrive in the same pristine condition of a shop -purchased , , copy. If it isn't, then we will replace it free of charge.

Please call Lindsey on 081-661 3614. Alternatively, 4AUMY! WpMbax,' complete the coupon below f p -,..,Fair. Ma

NAME TALKING TECHNOLOGY ,I -II ADDRESS

r Postcode -

-

I enclose payment for £20 by cheque/money order made payableto REED BUSINESS PUBLISHING GROUP. F Please charge my Access/Visa/American Express Card. f JJ[ lL][ II If Expiry date U

308 Supplement to Electronics World April 1991 Psst .. Powerfu/SoltwareSaves Time

ISIS - Intelligent Schematics ARES - Advanced Routing

ISIS SUPERSKETCH - our highly popular schematic PCB II - an exceptionally easy to learn PCB drafting drafting package. Still only £69 (basic library). package - ideal for the computer -phobic and only £69.

ISIS DESIGNER - no nonsense schematic capture ARES - advanced PCB design with netlist integration, with Netlist, Bill of materials and ERC reports. 10 routing layers, EMS memory support, DRC, auto Excellent value at £275. ground planes and more. Attractively priced at £275.

ISIS DESIGNER+ - Design Management Tool with ARES AUTOROUTE - our new autorouter uses an Hierarchical Design, Auto Annotation and ASCII data advanced multi -strategy algorithm to achieve very high import. Unrivalled features for just £475. completion rates. £475 price tag includes ARES.

o Auto wire router. o Topological Route Editor 01 o Auto dot placement. o Unlimited user configurable Auto label generator. pad, track and via styles. us Auto component finder. o Surface mount & metric 1 support.. (3 o Object oriented 2D drawing. o Comprehensive libraries. o 1 thou resolution. o Integral Device Editor. o 30x30 Inch max board size. o Object oriented 2D drawing for , ,.... . ,.,. - -- --0,.. o Output to dot matrix, pen plotters, lasers, POSTSCRIPT. silk screen graphics. o Export to DTP in IMG or DXF. o Drivers for dot matrix, pen o Runs on any PC compatible plotters, lasers, POSTSCRIPT, with mouse. gerber, NC drill.

COMBINATION PRICES SUPERSKETCH & EXT LIB & PCB II £149 Call for demo disks DESIGNER & ARES £500 abcenter DESIGNER & ARES AUTOROUTE £675 today - 0274 542868. DESIGNER+ & ARES £675 Electronics DESIGNER+ & ARES AUTOROUTE £850 14 Marr%ners Drive, Bradford. 8D9 41T Prices inc UK delivery, exc VAT.

CIRCLE NO. 117 ON REPLY CARD

' Custom metalwork ME1:3(DOD good and quick! 1. 4. Dataytcme i i .,,"I Q ,' ú tip; v

' ° / A2 ..

Plus a wide range of off -the -shelf products í GO K including:

- Nine sizes of standard 19' rack cases \,, New "clam" case in any depth ' Eight -card 1U Eurocard case - Audio, video and data patch panels NOW! Rack blanking and ventilation panels .,_ All use the unique IPK extrusion, giving strength A fully PC compatible A. and rigidity with no fixing screws in the front panel; cases can be tailored to your requirements. Eurocard solution to all Rack mounting str ps, cable trays etc. from stock. your embedded controller needs. i IPK 3roadcast Systems ' 3 Darwin(04)close ReadinFax: Berks RG23836 OTB

CIRCLE NO. 118 ON REPL Y CARD CIRCLE NO. 119 ON REPLY CARD

April 1991 ELECTRONICS WORLD+WIRELESS WORLD 309 With 48 experience in SMALL SELECTION ONLY LISTED- EXPORT TRADE AND QUANTITY DISCOUNTS years' the design and manufacture of RING US FOR YOUR REQUIREMENTS WHICH MAY BE IN STOCK several hund-ed thousand transformers we can supply: Tektronix 475 - 200Mds oscilloscopes- tested from £400 less attachments to £700 CAN manual probes etc. Tektronix 475A - 250wds - complete kit with probes- £750. Telequipment D755 - 50Mc/s oscilloscopes - tested C/W 2 probes + manual - £250. AUDIO FREQUENCY TRANSFORMERS OF Marconi TF2008 - AM -FM signal generator - Also sweeper - 10Kds -51014ds - from £350 tested to £500 as new with manual -probe kit in wooden carrying box - £50. HP Signature analyser type 5006A - £300. EVERY TYPE HP DC Current source type 6177C - £300. HP Frequency comb generator type 84064 - £400. YOU NAME IT! WE MAKE IT! HP Sampling voltmeter (Broadband) type 3406A - £200. HP Vector voltmeter type 8405A-£400 to £600. RANGE INCLUDES: HP Oscilloscope mainframe type 182C- £200. 180A £100. 1800 £120. 180D £140. OUR HP Oscilloscope mainframe type 181TR-£400. Microphone transformers (all types). Microphone Splitter/Combiner transfor- HP Frequency counter type 53526- 40GHzS - £5500. mers. Input and Output transformers. Direct Injection transformers for Guitars. HP Synthesiser/signal generator type 8672A -2 to 18GHzS - £7500. Multi -Secondary output transformers. Bridging Line HP Vector impedance meter and probe type 4193A-£1500. transformers. transformers. HP Network analyser type 8754A + HP8502A test set - £5000. Line transformers to B.T. Isolating Test Specification. Tapped impedance match- HP Mainframe type 8620A or C- £600-£1200. ing transformers. Gramophone Pickup transformers. Audio Mixing Desk transfor- HP 8505A network analyser -500Kds-1.3GHz e HP 8502A test set - P.O.R. HP 6640A signal generator- OPT 001-002- .SMc.s-1024Mc/s-£1000. mers (all types). Min ature transformers. Microminiature transformers for PCB Racal/Danadigital multimeler type 5001 - £250. mounting. Experimertal transformers. Ultra low frequency transformers. Ultra Racal/Dana interlace type 9932 -£150. linear and other transformers for Valve Amplifiers up to 500 watts. Inductive Loop Racal/Dana interface type 9934A-£100. GPIB transformers. Filter, Inductors. Amplifiers Racal/Dana timer/counter type 9500 (9515 OPT 42) - 1250Mc/s- £750. Smoothing Chokes. to 100 volt line Racal Thermlonic store 4 recorder - £300. transformers (from a few watts up to 1.000 watts), 100 volt line transformers to Racal frequency standard generators type MA259- 600Kds- 1 MC 8 SMc s- £200. speakers. Speaker matching transformers (all powers). Column Loud-speaker Marconi AF power meter type 8936- £300. Marconi bridge type TF2700-£150. transformers up to 300 watts or more. Marconi attenuator type TF2163S -1 GHz - £250. We can design br RECORDING QUALITY. STUDIO QUALITY, HI-FI MarconLSaunders signal sources types- 6058B- 6070A -60558-6059A - 400 to 18GHzS. P.O.R. P.A. Thurlby convertor 19 -GP-IEEE -488 -£ 150. QUALITY OR QUALITY. OUR PRICES ARE HIGHLY COMPETITIVE AND Philips logic muhimeter type PM2544 - £200. WE SUPPLY LARGE OR SMALL QUANTITIES AND EVEN SINGLE Microwave systems MOS/3600 microwave frequency stabilizer - 1 to 18GHzS 8 18 to 40GHZ -£ 1500. TRANSFORMERS. Many standard types are in stock and normal dispatch Microwave systems MOSS microwave frequency stabilizer -1 to 18GHzs 8 18 to 40GHzS- £300. times are and Bradley oscilloscope calibrator type 156 - £t 50. Short Sensible. Bradley oscilloscope calibrator type 192 - £600. OUR CLIENTS COVER A LARGE NUMBER OF BROADCASTING Tektronix curve tracer type 577 -£1000. AUTHORITIES. MIXIVG DESK MANUFACTURERS. RECORDING Tektronix plug -ins -7A13 -7A14- 7A18- 7A24 -7426-7411 -7M11 -7511 -7D10- 7S12 -St - S2 STUDIOS, - S6 - S52 - PG506 - SC504 - SG502 - SG503 - SG504 - DC503 - DC508 - DD501 - WR501 - DM501 A HI-FI ENTHUSIASTS. BAND GROUPS AND PUBLIC ADDRESS FIRMS. -FG501 A - TG501 - TR502- PG502 - DCSOSA - FG504. P.O.R. Export is a speciality and we have overseas clients in the COMMONWEALTH, Racal HF drive unit 1.6 to 25Mc/s type 1724 - brand new- £350. Racal HF drive unit type 1720 -1 MC to 29Mds -£150--£250. EEC. USA, MIDDLE EAST, etc. Alltech Stoddart receiver type 17/27A - .01-32Mds- £5000. Send for our questionnaire which. when completed. enables us to post Alltech Stoddarl receiver type 37/57 - 30-1000Mds - £5000. quotations by return. Alltech Stoddart receiver type NM65T - 1 to 10GIGS - £3000. HP Oscillographlc recorder type 7404A -4 -track - £350. HP Plotter type 98726- 4 -pen - £300. Marconi TF2015. SIGIGEN -10MHz-520Mc/s- AM/FM - £250. HP power meter type 431C to 18GHz with C type head 8 waveguide head -£150 to £200 S OWTER HP sweep oscillators type 8690 A86 + plug -ins from IOW's to 18GHz also 18-40GHz...O.R. Marconi TF1245A circuit magnification meter . 1240 8 1247 oscillators - £100 to £300. TRANSFORMERS HP signal generators Type 612 -614 -618 - 620 -626 - 628 -frequency from 450Mds to 21 GHzs. HP 86148- HP 8616A signal generators-800-2400Mds -1800 4500Mds-£600-4400. Gould J38 test oscillator - £250 e manual. Ferrograph recorder test sets - RST2 - £200. PO Box 36, Ipswich IP1 2EL, England. Raca /Dana 9301A -9303 RF mlllivoltmeters 1.5-2GHz - £350-£750. Racal/Dana counters 9915M -9916-9917 -9921 -£150 to £450. Fitted FX standards. Phone: 0473 252794 & 0473 219390 - HP 8407A . 8412A + 8601A network analyser- 100Kc/s-11OMds- £1000. HP 84108 network analyser -11 OMds to 12.4GHz or 18GHz plus most other units and displays used in Telex: 987703G Fax: 0473 236188 this set-up 8413A -8414A -8418A -8740A -8743A- 8750A P.O.R. NO. 109 REPLY HP 1417 mainframe plus -8556A- 85536-85546- P.O.R. - 8555A - 8552A - 85526 mug -in units. CIRCLE ON CARD HP 181TR mainframe -£400 -HP 182T mainframe -£500. HP 141T mainframe- £5OC-01000. HP 432A -435A or B - 436A power meters + Powerheads- 10Mc/s-40GHz. HP 478A- p486A-1(486- 8481A-84818. P.O.R. TEKTRONIX Image intensifiers - ex MoD - tripod fitting for long range night viewing - as new - £3000 EA. Thermal Imaging Equipment - high definition - from £2500 -complete in transit case. 7704A Main Frame Oscilloscope 250MHz Don 10 telephone cable - t2 mile canvas containers or wooden drum- new- Mk2-3 or 4. P.O.R. Infra -red binoculars in fibre -glass carrying case - tested - £100 EA also Infra-red AFV sights -£100 EA. 7904 Main Frame Oscilloscope 500MHz S.A.E. for details - Infra-red spotlights and Infra-red filters P.O.R. TM506 Main Frame Oscilloscope B 8 K 2019 analyser -2305 level recorder - 2425 meter - 4220 piston phones etc. P.O.R Geo Space System VLF receiver - phase comparator. 10-30kc/s+60kds+recorder outputs. 1-10-100ká 2815 Opti Fibre Scope New and Boxed + Used Ones s. Fx standard - £500. 2225 Digital Storage Scope ACL Field Intensity Meter Receiver type SR-209-6. Plug -ins from .Sills to 4GHz - P.O.R. Tektronix TR502 Tracking Generator -100kc/s-1800Mc's a TM500 mainframe. P.O.R. 7603 Main Frame Scope Marconi TF2361 Sweep Generator + + TM9693 0-300Mds + TM9694 - 220Mds-1000Mds - £350. SC502 Scope 15MHz HP 117108 Down Convertor -.01-11~ - £450. HP 86406 Signal Generator Opt. 001+003 -512Mds- £1200. 5223 Digitalizing Scope Narda Microllne Sweeper model 9535C - 1-18GHz - £2000. 106 Square Wave Generator Singer EMA 910-11 data evaluation unit - EMA 910-10 FX selection units + EMA 910-12 FX selection uno. 1 GHz-26.5OGHz total FX coverage - £2000. 191 Constant Amplitude Signal Penetrator Marconi distortion meter type TF2337A -£150. 134 Time Mark Generator H.P. pulse modulator type 11720A -2-18GHz. P.O.R. M.P. modulator type 8403A - £100-0200. TG501 Time Mark Generator M.P. pin modulators for above, many different frequencies -£150. DM501 H.P. 435A power meter (no head) - £200. M.P. 5342A -18GHz counter -£1600. DM561A Digital Multimetre Tektronix 308 data analyser -£350. SM502 506 Main Frame Systron Donner model 6053 counter/3GHz - £300. Systron Donner model 6057 counter/18GHz-£800. DM5010 Programmable Digital Multimeter M.P. 66408 opt 001+003 signal generator -.5-Sí 2Mds AM/FM -£1200. H.P. 745.746A AC calibrator + high voltage amplifier- £300. Phillips 3217 - SOMc s oscilloscope with probes 8 book - £300. S1 8 S2 SAMPLING HEADS J. & M. Computers Marconi microwave 6600A sweep osc mainframe with 6650 PI - 18-26.5GHz or 6651 PI - 26.5-40GHz - £1000. Plug ins Eight Acres, H.P. 86608 signal generator mainframe - £1000. 7A13 7650 7D02 7B53A Gt Totham Road, Wickham H.P. 86608 signal generator -1-t 300Mds. 86602A eext modulator PI 866316- £1500. 7A18 7BS0A 7D20 H.P. 8660C signal generator-1-1300Mes. 066026 -AM -FM modulator PI 866328-£2500. 7A24 7B71 7Sí1 Bishops Witharn, Essex A -£150. M.P. 3720A spectrum display - £200 - HP3721 correalator 7426 7B80 7St4 H.P. 3320A frequency synthesiser - .0t Hz to 13/Ads OPT001 - £250. Tel: Maldoft 0621) 892701 M.P. 5359A time synthesiser pulse generator -1 OMds- £400. Send £1.00 for list of test equipment Fax: (0621) 891414 M.P. 37555 + 3756A - 90Mds swhch - £500. H.P. 331A distortion analyser £150. Marconi TF2331 distortion meter -£150. J & M Computers specialize in all redundant Electronic Equipment, H.P. amplifier type 8447A - .1-400Mcls -£400. HP8447F -.1-1300Mds -0800. H.P. frequency counter 5340A- 18GHz -£1000. Rear output - £800 - 20GHz opt -£ 1100. working or not, i.e. H.P. spectrum analyser plug-in 8557A - .01-350Mc/S- £500 -OPT001 - £400. M.P. spectrum analyser plug-in 85586-.1-1500Mc 5-£1500. Computer equipment and peripherals Clark air masts. Heavy duty. Scam -40h or 7011- £200-£1000. Components (resistors to IC's) Gould K105 logic anz-£500 with twin disc. Test equipment Tektronix 491 spectrum analyser - 10Mcis-4OGHz - £1000. Tektronix 491 spectrum analyser -1.5GHz-40GHz -£1000. Modems Tektronix 491 spectrum analyser - 1.5GHz-40GHz - as new -£ 1200. Printed circuit cards Tektronix DC508A - 1.3GHz counter+TM500 mainframe- P.O.R. Redundant stocks EIP microwave counter 371 - source locking -18GHz -£1200. Tektronix mainframes - 7603 - 7623A - 7633 - 7704A - 7844 -7904 - TM501 -TM503- TM506 - End of job lots P.O.R. Cable Tektronix oscilloscopes -465B-466 -475- 475A -485 -2215- 2235 -P.O.R. Factory clearances hems bought from HM Government being surplus. Price Is ex -works. S.A.E. For enquiries phone for appointment or for demonstration of any Items, availability or price change. VAT ano Carr. extra. If you have redundant equipment now or in the future, would you Johns Radio, Whitehall Works, 84 Whitehall Road East, Birkenshaw, contact us. We would be pleased to price and collect it at our own Bradford BD11 2ER. Tel. No. (0274) 684007. Fax 651160. expense.

CIRCLE NO. 108 ON REPLY CARD CIRCLE NO. 110 ON REPLY CARD

310 ELECTRONICS WORLD+WIRELESS WORLD April 1991 UPDATE SPECIAL

,

1

, * 1,41 F14 v -

_ .;-11.. r ..3`=_ . .. '1".' "le". lí"#1. . 91P1.1 -G f . a jkir7

ON THE RIGHT TRACK

Marine electronics is becoming Navigating a small There has been a dramatic fall in price big business. Small boat own- for GPS systems. Four years ago a unit ers have never had a better boat is no longer a could easily cost £10.0(X). As recently as opportunity to pour money wet last year the price was in the £2500 brack- into high technology than at this year's matter of the et. At this year's boat show there were Boat Show. The satellite based global finger held aloft. sets available for as little as £1300 with positioning system (GPS) is emerging as a predictions that the price will drop below clear winner for electronic navigation Technology has made £ 1000 by the end of the year. They are against the traditional land based systems still more expensive than the land based of Decca and Loran. inroads and Steve equivalents. typically £600 to £700 for a The big boost for GPS has been its Rogerson reports on Decca and as low as £500 for Loran, but increased coverage with 18 of the planned some pundits were predicting that within 24 satellites in operation. This allows the latest equipment five years the price differential will have users to take a fix for more than 23 hours disappeared completely. in any 24 hour period. By the end of this seen at the Boat GPS has also been given an increase in year, shuttle launches permitting, all the popularity in a strange spin-off from the satellites should be up and giving an Show Gulf crisis. When the GPS satellites first around -the -clock service. went into orbit, the US Government

April 1991 ELECTRONICS WORLD+ WIRELESS WORLD 3I1 UPDATE SPECIAL

became concerned about the 10 to Ism DIFFERENTIAL GPS Mediterranean. Saudi Arabia, Japan and positioning accuracy achieved by civilian part of the South China Sea. Further trans- sets. The worry \\ as that it could he inte- GPS systems can be made more accurate mitters are planned for India but it still grated into a guided missile system or oth- using a technique called differential GPS. leaves large areas of the globe uncovered erwise used for military purposes. For this to work a second GPS receiver is including most of the British Isles. The US authorities responded by needed at a known fixed position. The Decca has all of the British Isles cov- putting a scrambling system on the satel- mobile GPS takes readings from the fixec ered, along with most of Scandinavia and lite signals that reduced the accuracy to station as well as the satellites to improve the north European coast. There are fur- only I00n1: military units were fined with the fix. With GPS descrambling, it is pos- ther systems in Canada, Japan, the Gulf, a descramhler. But with the large deploy- sible to get accuracies within a few cen- India, Bangladesh, South Africa and ment of troops into a featureless desert, timetres, ideal for surveying applications. Australia. Land -based systems are also every unit and section was to he given a Even with the SA switched on, accuracy more prone to weather and time -of -day GPS receiver. The trouble is that not can be within 20m at a limited range. The interference and their range and accuracy enough military units could be sent to the 20m accuracy can only be achieved within are not as good though Decca, at 25m, area in time and so civilian units were 30km of the fixed base station, and does heat a scrambled GPS. Loran, at pressed into service. This led to the US reduces to 100m at 160km. Some manu- 200m, is not a contender. Government switching off the scrambler facturers are thinking of setting up their Political problems also come into play. own base station networks for differential The Decca system was taken over by the if the INTERPHASE Star Palm GPS GPS US turns SA back on. British Government about three years ago

least one US firm is making a hybrid GPS/Glonas unit. If cheap Glonas systems 3 '1 .2-3 come on the then it .357- 19.3. 9. '4 75 6 market. seems incon- -028' - 7.4.. ceivable that the US would switch SA t y á ro hack on. thus reducing the positioning t o accuracy for civilian users: doing so would kill sales of the US system hard- ware stone dead. Chris Carter from Naystar put it this Navico's Star Pilot GI'S costs £2395 and way: "If a good, commercially viable Philips's ap Navigator six -channel stand- has a /28 X /60 pixel display, which is Glonas receiver is put on the market and alone GPS at £1950, which displays data responsible for the elevated price. the US implements SA. then Glonas received from wind instrument systems, Vessel's tracA is displayed. would outsell GPS, which would he com- with lay lines for true speed over ground. mercial suicide for the US manufactur- system - called SA for selective availabili- ers." But Brian Grant. a consultant for although Decca still manages it. The prob- ty. The US has said SA will go hack on Navico, said that Glonas is too sophisti- lem is that the Government is only guar- after the Gulf crisis is over. but that deci- cated for the leisure industry. Ile didn't anteeing transmissions until early 1997, sion will surely depend on the progress of envisage that low price Glonas sets will after which Decca may not exist unless a the Russian Glonas system. come in. at least not as low as GPS. private firm takes over the transmitter This is again a satellite based system Satellite systems enjoy virtual global chain. The Government intended to hack with no SA equivalent planned. Russia is coverage. In contrast. Loran only cove s the Loran system, assuming that it would approaching manufacturers with a view to the American coast states. Norway, get funding from the European partners. producing versions in the \Vest and at Iceland, the north of Scotland, the However, other countries are updating their Decca chains and seem unlikely to NEW GPS RECEIVERS sanction extra money for Loran. Navico's Grant summed the commercial possibili- Companies showing new navigation prod- receiver, but most of the extra cost clearly ties this way: "In five year's time GPS ucts all went for the GPS system with price went into its large 128 x 160 pixel super - will have very low price systems and he as the selling point. The winner at £1300 twist lcd display Accuracy is15m.Cetrek the main player. Loran will he in Europe wasthe Pronav GPS100 available from was doing something different. A GPS sys- and he sustained for European military three UK distributors - Regis Electronics, tem is made up of a black box, antenna and reasons as an alternative to GI'S and SM International and Marine Electronics display, but the firm was selling its black Glonas. Services. It measures just 159 x 100 x box for £1295 for owners of its chart based "But GI'S is so universal and accurate 51 mm and weighs about 0.7kg. But the navigator. This is a cartridge system with that it will he in the hands of the US with firm must have been looking at last year's each cartridge containing details of a partic- no commercial hack -up if European coun- price lists when it made its claim that it ular area of coastline. The .GPS system tries do not put up the money. It will he a costs around £600 less than its nearest links into It to show sailors where they are problem getting fishermen to scrap Decca, rivals.Try telling that to Marconi which had a on the display. The chart system itself costs but GPS is so accurate that some fisher- range of Koden GPS units priced between £3000.Even more different was the Naystar men are already asking for it.'' £1350 and £1900 including the GP910. Like XR4-PC.This is a computer expansion card the Pronov product, it has an accuracy of intended for the OEM market and people 15m. And Shipmate was showing its who want to value add to systems. It turns RS5500 unit at less than £1500 with an an IBM XT or AT -compatible computer into accuracy of 8m. Not really in the price war a GPS development system. Editorial survey: use the information at £2395 was Navico with its Star Pilot GPS card to evaluate this article. /tern J

312 ELECTRONICS WORLD= WIRELESS WORLD April 1991 A 20MHz top quali oscilloscope for£270? This special cffer, only available through Electronics World + Wireless World, represents unbelievable value.

send in a Oscilloscope offer, Room L333, We t -awe assured ourselves that the Model To place your order please Electronics World + Wireless World, 102E osci loscope from Japanese chegLe for £310.50 (wh ch includes VAT) to inst-unent manufacturer, Leader the aidre.ss shown. Alternative y complete Quadrant House, -he Quadrant, Electrcnics, more than meets its published the coupon with your credit ca -d details or Sutton SM2 5AS speafcation and is of an exceptionaly high phon_ in your credit card order on 081-661 build quality. Our judgement is backed by 3514 (mornings only). an unequivocal guarantee. At £270 (inclusive of test probes, LEADER OSCILLOSCOPE 1021 ORDER FORM packag.ng and delivery but excluding VAT) Please send me the specia off, r ns* rumen the iistrument is an absolute bargain.

I enclose a cheque for ©105( fine VFTI Reed Business 'ubl sh inc Gray{ 2J MHz dual channel operation r yible to Varable. trigger hold -off Please debit my credit card 5mM/div Y11Y2 sensitivity at 20MHz Expiry date 1 mw'/clv Y1/Y2 x 5mag at 71/Hz 230-isldiv to 0.2s/div sweep rate Access Visa Ame dear Express Diners Club To Me sum of £310.50 DCto 500k1 -z X bandwidth Y/lr.operation using Y channels Mr. Ms (with XPr pfuse shift <3° at 20kHz Name. 8 cm x 10 cm display area Address Cal bration accuracy better than 3% Daytime tel no: 1kHz internal calibrator Signature Spezial video signal trigger modes .Rise -time <17.5ns CrEticule illumination TwSx-10 probe kits included; Ln.equivocal guarantee d rr na, t1Y,r%V 410 ,. ~Jo '.d ] K w. : r ! . . ]IYl 41u, r,

d o.

vYor.i gv .x. /i .r.

.11 nib \` 1.~`` Jr . -Al

d L np -. v

C

t áj6 ilI' ..

11` RAEDEK ELECTRONICS

BANNERLY ROAD, GARRETTS GREEN, BIRMINGHAM B33 OSL, ENGLAND Tel 021-784 8655 a d Fax 021-789 7128 Eir Electron Tubes

CRT's IGNITRONS KLYSTRONS y MAGNETRONS PLANAR TRIODES RECEIVING RECTIFIERS SPARK GAPS

TETRODES THYRATRONS TRANSMITTING 8775::

TRAVELLING WAVE TRIODES SOCKETS & ACCESSORIES R.F. Power Transistors MOTOROLA GENERAL ELECTRIC R.C.A. JOHNSON 1/4 iri vr THOMSON-CSF REGENCY WILSON T.R.W. MSC ACRIAN 1/4 ., 1 TOSHIBA NEC MITSUBISHI PHILIPS AMPEX MULLARD 1 ..-.b Also in Stock ti / THYRISTORS MICROWAVE DIODES ZENER DIODES CRYSTAL OVENS R.F. POWER MODULES R.F. CERAMIC CAPACITORS RECTIFIERS RECTIFIER STACKS JAPANESE 2SC TRANSISTORS JAPANESE IC's VIDEO ACCESSORIES (MOTORS, HEADS, BELTS etc) R.F. HEATERS / CATHODE RAY TUBES (CURRENT AND OBSOLETE TYPES, MICROWAVE OVEN MA3NETRONS) HOME AND INDUSTRY LINE OUTPUT TRANSFORMERS (FOR A LARGE RANGE OF MONITORS) VACUUM CAPACITORS

CIRCLE NO. 120 ON REPLY CARD

C Ready for hours ssebly NEW TO THE WORLD a In OF TV? Prototype1.2Prototype or in need of updating? Then why not attend "INTRODUCTION TO TV PRINCIPLES FOR ENGINEERSt"

** Next course: 23rd - 26th April ** oo tato d to be held at the W o r k s s U CROSSMEAD at tt rtotypeboa CONFERENCE CENTRE, Directly gropo EXETER alrntive Zhe dr¡ ,it9plotter n9 tFree textbook, worth £47.95, with each place i11in`ad1...P rate crctbd Irons sddmaXtm"os Write or phone for details. Nigh goóeed plston SOD. ,tdiñ9 Cad System-_::.r Snterfiace li Gerber J1, - JAMES BR/CEASSOC/ATES c1 TRAINING SERVICES FOR THE TELEVISION INDUSTRY =[ z.CKS 2, COURT GARDENS, STOODLEIGH, L "`N T TIVERTON, DEVON EX169PL 'Meadows' IBA Beech Coppid Lane Wokingham Berks RG11 5PJ Tel. & Fax. 03985 515 Tel: 0344 860420 55046 Fax: 411346 Tlx: 849462 Telfac G

NO. 121 REPLY CIRCLE ON CARL) CIRCLE NO. 122 ON REPLY CARD

31.4 ELECTRONICS WORLD+WIRELESS \\ORLD April 1991 APPLICATIONS

Adding a range switch to a DPM

71R DIGn tcD 01sRlAr

IOU

Although many low-cost digital panel this supply, available at the I38's V- pin, an analogue output. Any function is meter chips now exist, they are commonly at currents up to 0.5mA. obtainable with the correct rout program- designed for a single range and have no Maxim Integrated Products (UK) Lid, ming. provision for different voltage ranges. 2 IC Horseshoe Park, I'angbourne, Analog Devices's AD7569 (below) When input switching is needed. one solu- Reading RG8 71W. contains both data converters. so that with tion is to use solid-state devices in a thk device. a Sierra Semiconductor divider arrangement. but this does mean SC22102 rom and a quad Nand such as that the switch resistance has to be taken the 4093 to carry out logic and timing into account when designing the divider. Function generator functions. a three -chip function generator Since the resistance is not accurately can he made. as described in Application known and varies with temperature and with linearisation Note E1369 and shown in Fig. 1. Input power supply voltage, the method is not When a complex or discontinuous func- and output ranges are pin -programmable. ideal. tion must he generated, it is now common Since input impedance is low and bias in the circuit shown, which is taken to use an A -to -D converter feeding digital current rather high, it is expected that an from the Maxim 1990 Applications addresses to a rom. which provides a input butter will he used. Data from the Handbook. using the differential inputs of unique code to a D -to -A con,erter to give A -to -D and to the D -to -A use a common the MAX 138 panel meter module removes the IR voltage drops across the Ov°° analogue switches in series with the preci- BANDGAP sion resistors. The second set of analogue REFERENCE switches has no current flowing in it and simply connects the 138 input low pin to va,,, TRACK --o vw RANGE the bottom of the divider resistor in use. NETWORK HOLD a L so that the voltage drop in the current -car- rying switch is not seen. A negative supply voltage is needed by the analogue switch if it is required to AD7589 pass positive and negative inputs. Since ODGND the 138 contains a charge pump to gener- ate negative voltages. low -current switch- O 0 AGND.a AGNDo. es such as the DG509A shown can use a wR

April 1991 ELECTRONICS WORLD+ WIRELESS WORLD 315 IN VIEW OF THE EXTREMELY RAPID CHANGE TAKING PLACE IN THE ELECTRONICS TH U RLBY INDUSTRY, LARGE QUANTITIES OF COMPONENTS BECOME REDUNDANT. WE ARE CASH THAÑDAR PURCHASERS OF SUCH MATERIALS AND WOULD APPRECIATE A TELEPHONE CALL OR A LIST IF AVAILABLE. 'pan éóil 3 . WE PAY TOP PRICES AND e erlR SSSS tiaf-,Rrt 0,--01- COLLECT. R. Henson Ltd 21 Lodge Lane, N. Finchley, London, N12 8JG. 5 mins from Tally Ho Corner For Digital Telephone: Multimeters 081-445 2713/0749 Whatever your need in DMMs, Thurlby-Thandar it. can supply CIRCLE NO. 111 ON REPLY CARD With prices starting at just £39 + VAT, the range includes both hand-held and bench models. EPROM PROGRAMMERS Display resolution varies from 31/2 digits up to 5'/2 MODEL 200 - £295 (other models from £195) digits and accuracies are from 0.5% up to 0.01%. Includes MSDOS driver software, serial cable, comprehensive manual, 32 pin ZIF socket and universal object file Some models offer True RMS AC, frequency editor/converter. measurement, conductance measurement and Programs virtually all EPROM devices currently available including micro - digital interfacing. controllers (nearly 60011. Emulation capability with our E512 or the Greenwich Instrument emulators. Easy to set up - not a plug in board. 12 Month Guarantee. Money back if not completely satisfied. Designed, manufactured and supported eaónr in the UK. -2-35q52 A- Z8 ADAPTER PIC 16C5x ADAPTER m`ciooalo©ó ¢ FOR MODEL 200 FOR MODEL 200 Programs Zilog and SGS parts Available for DIL or SOIC parts All Security Functions Programmable Manufacturer approved algorithms £75 From £75 Increasingly 0j1 popular 8 bit microcomputer avail. The 16C54/7 is a range of low cost, low power, able in CMOS versions. high speed microcontrollers ideally suited to low or high volume developments .1 8 PIN SERIAL EEPROM ADAPTER Adapters available also include FOR MODEL. 200 8748/41 family £75 Reads & programs over 50 devices 8751 family £75 12C (M8571, X2402), 9306, 2506 etc. 40 pin EPROMs up to 4 Mbit £75 £95 63701/5 from £75 1905a As used for security devices in many car radios. 32 pin PLCC EPROMs £85 mobile radios, cellular phones a security 647180 systems. £125 This low-cost 51/2 digit bench DMM combines Other families in development -please enquire.

exceptional resolution and accuracy with We also sell Bipolar and Gang Programmers, EPROM Emulators and computing power and data logging. It costs Erasers and a universal cross -assembler for IBM PCs and compatibles. £349 + VAT. Write or phone today for Free Information Pack Tel: Contact us now for full details of all our DMMs. (0666) 825146 Fax: (0666) 825141 MOP ELECTRONICS, PARK ROAD CENTRE, Thurlby-Thandar Ltd. MALMESBURY, WILTSHIRE, SN16 O UK Scandinavian customersmers please contact: Glebe Rd., Huntingdon, Cambs. PE18 7DX. m Digitron A/S, Alesund, Norway Tel: (0480) 412451 Fax: (0480) 450409 Phone 071-45890 Fax 071-45453 German customers please contact: 145.4 Synatron, Grasbrunn B. Munchen, Germany Phone 089/4602071 Fax 089/4605661

CIRCLE NO. 112 ON REPLY CARD CIRCLE NO. 113 ON REPLY CARD

316 ELECTRONICS WORLD+ WIRELESS WORLD April 1991 APPLICATIMS

.5V C7 y UP C8 100nF T00nF POLARITY O/P DIP LO RANGE E C5 R5 HIGH O SC22102 - 1 68pF 6k2 AD7569

CI ""'" 1nF V

R2 R1 41--1 1 U DI --i

4093 C2 1 10pF R3 3 rt 475 SV

C8 C41100PF D4 R4 100NF R5 I 100k C3 2k2 11-, 10pF

Fig.1. Three -chip function generator.

(5-1._ T1(304) T241us I Fig.2. WW'areforms in the function gener- ator. Circled numbers refer to Fig.!. 250ns

Fig.3. Using the generator to linearise signals from a transducer. 400ns1 7 port and it is therefore convenient to use a torn with multiplexed address/data bus, U f 2" I the SC22102 eeprom being such a device. 250ns Both converters are 8 -bit devices, so accu- racy is 0.4%. o Í1 Clock pulses at a maximum frequency of 250kHz, A -to -D triggering and (1) RELAXATION OSCILLATOR WAVEFORM 1.1 /(714.T2) (2) MONOSTABLE 1 OUTPUT - DRIVES WR OF THE AD7569 DAC. write/read control is provided by the four (3) MONOSTABLE 2 OUTPUT - ORIVE3 OE OF THE SC22102. (4) A07599 BUSY OUTPUT. gates in the 4093. Waveforms, identified (5) BUSY DELAYED BY 250ns TO LATCH ADC O/P INTO SC22102 by circled numbers, are shown in Fig. 2. ADDRESS LATCH WHEN CONVERSION IS COMPLETE. No setting up is needed unless the sam- pling frequency is to he precise, in which case R1 should he set so that Ti is at least SUMMING the the INPUT OUTPUT 500ns longer than BUSY signal of AMPUF1ER AD7569 and T2 then set to give the cor- rect frequency. FUNCTION ATTENUAfOR 1 Programming the roan is simple and the GENERATOR author points out that he built a program- mer to plug into he Centronics port of a personal computer (a 12 year old PET signal is 2% and the correction applied to which is 0.008% or around 14 bits. The with a modified operating system). the signal front the function generator's application note gives full details. One application is that of the linearisa- A -to -D is 2%. then the resolution to which tion of transducer signals: Figure 3 shows correction is applied is the 0.4% of the Analog Devices Ltd, Station Avenue, the principle. If the non -linearity of the function generator multiplied by 2%, Manton on Thames, Surrey KT 12 HT

April 1991 ELECTRONICS WORLD+ WIRELESS WORLD 317 APPLICATIONS Turning off mosfets

A ntoslet's input capacitance amounts to turns on to discharge the mostet input several thousand picotarads, which must capacitance rapidly. The rener protecrs D1 INPUT OUTPUT he charged to 5 or 10 volts to turn the the gate front overvoltage. mostet on and discharged to turn it oft. Motorola's MDCI000A/B/C (Fig 2) is Turn -on is relatively simple, but to drive an integrated equivalent to that in Fig.I, the input voltage below the gate/source except that the p -n -p transistor is replaced threshold voltage needs some kind of by a complementary pair to form a silicon active network, which normally consists controlled rectifier. which discharges the

nlosfet gate capacitance faster; the protec- RETURN tion cener is also incorporated. A circuit DC symbol for the device is shown in Fig.3. I'ig.2. OUT Integrated drive using When the input goes low. the SCR turns complementary pair. on rapidly, the gate capacitance being dis- charged until the SCR turns at the oft OUTPUT point where the moslet gate charge is too low to provide holding current for the mostet. Mosfet gate voltage al this point is less than I V and the time to discharge 1000pF from 9V to IV is 15ns. Figure 4 shows the MDCI 000A used in the P1\"á-1 switch of a power converter, INPUT Fig.]. Common mos%el drive in which current is taken from the emitter arrangement. of an output transistor in the MC3406OA oscillator and passed to the mostet via the of several discrete devices. as seen in Fig. MDC1000A. The 300ohni resistor limits 1. Motorola's Engineering Bulletin current to the turn-off device and the

EB142 describes an integrated device to 680pF capacitor provides a little extra RETURN perform the function rather better and at urgency at turn on. lower cost. Motorola Ltd, European Literature Fig.3. Circuit svmbolforM/)CWOO. In the circuit of Fig.l. the gate capaci- Centre, 88 Tanners drive, Blakelancls, tance is charged to the level of the input Milton Keynes Mk 14 581'. less the diode drop, the base of the Editorial survey: use the information MPSA55 being clamped off by the diode. t ig.4 below. MI)CIOOO used in card to evaluate this article. Item K PWM When the input goes low, the transistor switch of power converter.

Vin 12 to 26 V MR850 . Vow 28 Vt0.5 A 150 µH 20µH @4A @1A /22k

10

0.05 µF VCC 33 k

2 . 4.7 k w. 2.7 M 680 pf 1, COMP

50 µF ._. 14 MC34060A MTP50N05E + +' 35 V MDC1000A 470 µF - 470 µF 13 35V 35V 39 k

12 ref GND

DT CT RT

4 6

4.7 k 0.001 µF

390 47 k 1 O o Fig.4 *Optional to minimize output ripple

318 ELECTRONICS WORLD+ WIRELESS WORLD April 1991 M & B RADIO (LEEDS) Industrial THE NORTH'S LEADING USED TEST/EQUIPMENT DEALER Spectrum analysers Special Offers HP 141T 8554Ú8552A 0.1 to 1200 MHZ analyser Dryf it A200 12 volt 20 amp/hr Batteries E24 (new Vuasa NP38/1212 volt 38 amp/hr Batteries E30 141T) 02950 RS 500VA 240V Primary 110V secondary isolating HP 182A 8558B Spectrum Analyser 0.1 to 1500 transformers in yellow GRP enclosure 040 computers MHZ 12500 RS 500VA 240V Isolating Transformers C35 HP 180TR 85588 Spectrum Analyser 0.1 to 1500 HP 85 Desktop Computers 095 MHZ 12300 Marconi TF995 1.5 MHZ to 220 MHZ AM FM SIC/ HP 8551 Spectrum Analyser 10 MHZ to 40 C60 GHZ £850 Drake (SR 3240E Satellite Receivers 0100 HP 8553B Analyser Plugins [350 Fluke 77DVM Case Cal Certificate 1130 Tektronix 491 Spectrum Analyser 1.5 to 40 GHZ Tektronix 141A Pal Colour Test Generator 1850 New Book £1350 Tektronix 1485C Waveform Monitor 1750 Wayne Kerr RA200 Digital Audio Response Tektronix 1481C Video Waveform Monitor C600 Analyser ' 0850 Tektronix RM529 Waveform Monitor 1195 Tuscan 9900 Sweep Analyser 450 MHZ E550 Philips 5334 TV Sweep Generator 0250 Tektronix 7D01/DF2 Logic Analyser C750 Marconi TF2162 MF Attenuator DC to 1 MHZ 075 Marconi TF2432A 560 MHZ Freq Counter £275 Oscilloscopes Marconi TF2432 560 MHZ Freq Counter C190 Tektronix MHZ 4 Trace £1750 2455 GPIB 250 Systron Donner 6053 Frog Counter 20HZ to Tektronix MHZ 4 Trace 2455 250 11600 3GHZ C225 Tektronix 2445A 150 MHZ 4 Trace C1500 1 WATSU SC7104 Freq Counter 1 GHZ 9 Digit [400 Tektronix 5223 Digitizing Oscillosope 5B25/N Tektronix DC508 Freq Counter 1 GHZ 1450 7 5A18 (1000 Tektronix DM501/TM501 Digital Multimeter E295 Tektronix 2225 50 MHZ Dual Trace £550 Farnell TM8 RMS 1 GHZ Sampling IEEE Meter E375 468 Tektronic Digital Storage GPIB (1200 Farnell TM4 Millivobmeter C135 Tektronix 76037A18/7A18/7B53 £500 Ferro graph RTS2/ATU1 Audio Testset C300 475A 250 MHZ Dual Trace C550 Tektronix MJS Electronics 401 Noise Level Testset C350 475 200 MHZ Dual Trace in good clean Tektronix Wayne Kerr B421 Autobalance Component order £495 Bridge 0150 Tektronix 5403 5048 5018 5842 4 Channel [450 Wayne Kerr 8900 Automatic Bridge 0250 MHZ Trace Tektronix 455 100 Dual D/L RFL 5950A Crystal Impedance Meter E175 Timebase 1195 Burndept Absorption Wattmeters 0 to 500 MHZ 50 Philips 3217 50 MHZ Dual Trace (as new) with Ohm 3 ranges to 100M W. 0 to 300M W. 0 to 1 5 probes etc £350 -0 watts C40 Telequipment D83 Dual Trace 50 MHZ E250 Racal VHF/UHF PMR Calibrators E75 Telequipment D755 50 MHZ Dual Trace C250 with TV/Line Signal Generators Could 0S3350 Oscilloscopes Marconi TF2008 10 KHZ to 520 MHZ AM/FM Kit 0200 Trigger Box E395 05350060 MHZ Dual Trace £300 Gould Marconi TF2016A 10 KHZ to 110 MHZ AM/FM E275 The flex -l -b -le solution MHZ Trace Gould 0S260 30 Dual 0190 Marconi TF2015/2171 Synchronizer 10 MHZ to 520 Telequipment DM63 50 MHZ 4 Trace Storage C325 MHZ E450 35 MHZ Dual Trace D/L Cossor CDU150 Farnell SSG 520 520 MHZ Synthersized 1750 Timebase 0135 Philips PM5234 100 KHZ to 110 MHZ AM/FM r 7922R Rack Mount A PC/AT/386/486 compatible Tektronix Dual Beam 0295 Sweep 0200 Tektronix 10A2A 11132S (125 647A Oscilloscopes Philips PM6456 Stereo Generator 0185 General T/M HP 6060 50 KHZ to 65 MHZ Sig/Gen E100 A Steel cased HP 427181 MHZ LCR Meter C900 HP 6168 1.5 GHZ to 4.2 GHZ Sic/Gen C75 HP 5340A Freq Counter lO HZ to 18 CHZ (1000 HP 6188 3.8 GHZ to 7.2 GHZ Sig/Gen [75 proof HP 5345A Timer Counter C450 HP 612A 450 MHZ to 1200 MHZ 0125 A Splash/dust HP 1415A TDR with Genrad Connectors C200 HP 6518 Test Oscillator E100 HP 34000 True RMS Voltmeter E145 HP 334A Distortion Analyser [300 A 8088 to 80486 CPU HP 3465A Digital Voltmeter C150 Marconi TF2331A Distortion Factor Meter [295 HP 8112A Programmable Pulse Generators C1400 131.0 Wow and Flutter Meter WM2 E250 Kathrein MFK80 TV Field Strength Test Set C400 Woelke ME120C Wow and Flutter Meter 1190 A Any disk combination Racal RA17L Communications Receivers E225 Marconi TF2300 AM/FM Mod Meter E150 Racal RA117 Communications Receivers C350 A Up to 10 free slots ALL PRICES PLUS VAT AND CARRIAGE Send, or call today for details. Leeds LS1 4BB BLUE CHIP 86 Bishopsgate Street, Telephone 0244 520222 TECHNOLOGY Tel: 0532 435649 Fax: (0532) 426881 Hawarden industrial Park, Manor Lane, Deeside, Clwyd , CH5 3PP Fax 0244 531043

CIRCLE NO. 124 ON REPLY CARD 1

WE HAVE THE WIDEST CHOICE OF USED PHILIPS PM1525 Dig/al Multilunetion Multimeter 417 to 541 digit 1325 OSCILLOSCOPES IN THE COUNTRY 00091(1 224 Programmable Lumen Source £1000 RRROGRAPH RIS2 Reenter Test Se' with AIL As New 1600 RRROGRAPH RIS2 Orville, Test Set him 1150 TEKTRONIX 7445A Four Iraca I50MH2 Dual 1B [1100 460 VANE CIMRACTERSTICMETER VCM163 [300 If y1.08112235 Dual Tras 100W1 Dear Sweep 6600 1HUR1By P5U PUIDMO 30V.4Quad ltd Di[ilal 1700 Ire` CPU 2225 Dual irate 50vnr De at Saerp 1650 1110011 Bench P500-404 O- SOR Metered 0100 DKr ONX 2215 Dual trace 601.X1 Deicer Smelt 2450 FARRELL PSU H30/1000-30V 0-1000 1150 It rli ONI1415 Dual iras 200'/Hl Delay Seen, 6550 500/0 X10 tole Mays« 32 Channel £500 loro OMs 465 Dual Irate 100MNi Delay Spero 2450 IBM IELFOU'PML9I C171 Curve Tracer 1250 -PC bus 5616088ERGER ENERTEC 5218 Three Trace 2000111 Delay Sweep 1650 MARCONI 92700 Universal LCR Broge Battery Pm [125 5C111108ERGER ENlRTEC 5220 Dual Trace 100MH2 Delay Sweep 1000 MARCON 11.3371 Aulomahc Distortion Meter £0091 111H1 01% (115 PN TIPS PM3217 Dual iraca 5014111 Oe,ay Sorer L400 MARCOS MUD Mrlert 02300 1123008 112163 tram (100 TELEOUIPMENI 0755 Dual Trace SOMH10elar Semi [250 RACAL 9915 Fred Ce.Mer 10-520MH1 Cmta 0 en 1150 GOULO 053000 Dual Trace 40MH1 Dear Sweep 1V Trig L150 input/output cards GOULD 051100 Dual Trace 30MN11V Trig (Ho 010 1 6 140 9 M3LIIMEOERS Good Nor& rig order pNrsicalN nor brilliant COULD 0S310- HIGH DUALITY 20MHZ Dual Trace - Ieaas 2mvicrn 5,0l light Wright NON OHS' 1115 Supp.iee myth batteries A -0111110 No 8M6 Porn 165l0 Mar berm Ivan some M the New Rubbish available) Other available Tell Sit 1, Boss 070

GOULD 052508 Dud hace 15MNI N Trig I1á0 PHILIPS PM6622 Unrwrsai IrmeriCouniw 8081119.digt 1130 SCOISX 14015 Dual Trace 15MHZ (IS 11006060 51/606 5aero fun Gen Srrc5R4n 00111- PM/ 6110 TELF W PMENT D614 Dual Trace 101.1112 El 2n EEDBAC116600 Fun Gen Srne'S64n 001x1 -1000X1 (S3 S( LABS SMI I I Dual trace IbMHl II I 400 VALVE TESTER 01160 Suitcase title 22 Bases 240 TEKTRONIX 468 Digital Storage Dual Trace 100MH1 Delay /SMMI Sampling (Valve Data N01 INCLUDED) Rala 11750 111900X/0 2210 [Nita Storage Dual Trace 50MHZ 20MSis Sampling LEADER LWI46a two Ch AIVmeer 5X1-500011. ImV-3004 [100 Rale 11150 MlUSUI 451123 AC Vmele Dual Ch IOHI-500091 30010-100V [1S GOULD 1421 Digital Storage Dual Trace MINI 1150 50LARIR000 7045 Mu t mete 141 diga 30 ranges AutoMan 195 GOULD 4035 DNgdal Storage Dual Trace 200/2 1750 GOV(D 0S4020 Digital Storage Dual Trace 10MHZ 5450 Urge range of BENCH PONER SUPPLIES available Min 140 TEKTRONIX 434 Dua Trace 251.042 tube Slow 1250 XY PLOTTERS Various mode's Irom [a-Goo NNIS 151ÚS1 A SIMPLE - MANY 01111 115 AVAILABLE TOME 81111E1. 61aAFR EQUIPMENT WW1 AIMMLL 864001 Oscilloscope Calibrator 192 with Cal Cent 1600 MAS( EMOUIIE D80000 1061 Auto Cal OMM True RMS ec 1650 501ÁR1000 1075 DVM up lo 742 digit AC/RMSNCIONM [700 MARCONI 112008 AM 1M 100X1-5108111 Sig Gen [400 EQUIPMENT MARCONI 102015 AMIN 10-5201011 Sig Gen with 1(2111 1400 M.V. EG OSC 0.010 rE HMIu05 Inpie Tract IDOMH/ Dear hmebase 6792 MARCONI112015 without Synchronise 071II [750 HOVEL 056 LIOSCOPE 110004 Due 1r aye 61911/ Delay Seeep 1610

MARCO/ 92016 AMT/ 10 0/12-1 7 0MHZ Sig Gen with 112113 2350 HAMEG OSCILLOSCOPE 104203 1 Due, (race 20MH1 Component Testa 1121 MARCONI 92016 without Senchronnn 112113 (175 MAIEO OSCILLOSCOPE HM2053 Duel Trace 2O4.Hr Digital Storage 1610 MARCONI 92356 2357 Lee« OM.tAeln 20011 Me parr [950 All Mks mode/i available- all oscilloscopes supplied with 2 panes HP 8520[ 5eerper Ma n Frame IPug-ins avarubiel [I000 LEADER LVS51151A VMorscape 1600 BLACK STAR EQUIPMENT IPSP all units 051 (AR1ELL PSG520N Srotliescrd Sig Gen 100890-520M012 1100 APOLLO 10 1001111 Rat. Pnrnd Time interval etc £222 2060 124 DC Input APOLLO 100 100MÚ IAt ate« w ih more IunOxoS) lots MARCOS SANDERS 60558 Sg Source 800-2150MH1 [400 811E0R 100 fREOUEYCY COUNTER 1001,1 [101 MAR601. SANDERS 6010A Sig Source 100-1200902 [100 NEIEOR 600 FREQUENCY COUNTER 60091/ [135 RACAL 9081 SPHnesised Dig Gen 5-520040/ 075 METEOR 1000 FREQUENCY COUNTER 1681 (Ill T7 RAC/ 9009 Mod Mile, 106X11 -I 5GHZ LI50 IUPIOR 500 FUNCTION GEN 0 IHr 500lor Sine SO In [110 ORION COLOUR BAR GENERATOR Pal N Video 0709

Analmee 1 [Gill Iron [1000 C1400 TEKTRONIX 491 Spectrum 5-12 Ill outer 8/ok Star Equipment available T/Ir+ ~ 1ge HP Spectrum Analyser System with 8555A 6 IF Pug -m 10MNZ- of 1411 A 13150 I8GHZ HUNG CHANG DMM 1010 3 digit Hand held 28 ranges HP Spectrum Analyser System air 8554 6 IF Plug-in 5000/12 1411 ledudmg 10 amp 00001%ACC (P&P Gil 0950 O na, i- ®ue an lital 12501012 07500 As above DMM6010025% 0350 HP 1411 Spectrum Analyser System with 8553 6 IF Pug -in 1011 Carrying cases IM above WO ea 1IOMNI £2000 and wat« ;iog 1. - A M..RCONI 92370 Spectrum Analyser 1101401 11000 OSCILLOSCOPE PROBES Switched 111110 (P&P 13) 111 SVSTRON DONNER 1702 Gen 1950 9g 10011-IGl1 o 4G111 1600 ' in the IN 86167 Sig Gen 16-2 A resigned and made UK 11P 8610 Sig Gen BODIAHZ 20691 /500 A 3 year warranty This Is a very small sample of stock. SAE or telephone for UST of OVER 700 ITEMS. Please check availability before ordering. CARRIAGE all units 118. VAT to be adder, to total of goods and carriage. A PC/AT and PS/2 cards STEWART OF READING III. VISA 110 WYKEHAM ROAD, READING, BERKS RG6 1PL Tel: 0734 68041 Fax: 0734 351696 Atk Send, or call today for details. BLUE CHIP Callers welcome gano le 5 30pm MONLFRÍ (UNTIL Born THURS) Telephone 0244 520222 TECHNOLOGY CIRCLE NO. 123 ON REPLY CARD Ha warden Industrial Park, Manor Lane, Deeside, Clwyd , CH5 3PP Fax 0244 531043

CIRCLE NO. 125 ON REPLY CARD PROGRAMMING

L t ' a INTERFACING WITH C PART IJ

Kalman filters are not exclusively the preserve of mathematicians. In this part of his series on C, Howard Hutchings brings the subject down to earth by describing a practical filter used for measuring temperature in the F, presence of noise.

If you are not confused, then you are misinformed Kalman filters - predicting (2) You have heard of Kalman filters, uncertainty but never found the time to fully Kalman filtering is an important com- understand them. puter application and a specialist area. (3) You have never heard of them, but Interfacing with,C Connecting a PC to an external device the prospect of predicting order out of is an effective means of acquiring a apparent chaos has a certain perverse realistic understanding of this method The collected series of articles appeal. of digital -signal processing. The aim is Numerous military, industrial, Interfacing with C' is now and to remove random fluctuations and to scientific applications exist. Undoubt- , ávailable in book form price ° establish trends. In this sense, the edly, many of the remarkable techno- £14.95. Kalman filter is a digital estimator logical achievements of the past 30 The source code listings for the designed to remove noise, although years are due in part to Kalman filter exemplay programs which this is not clear from the literature. theory. A few of the more spectacular accompany the series are Most books are written by specialists include: available on disk (please state 31/2 who seem to think Kalman filters exist - the navigation of the Apollo or 51/4in media) price,£25.50 + for the purpose of manipulating spacecraft - this involves mid -course mathematical equations. This makes correction culminating in the VAT.` . control of getting very Prices include postage and started difficult. I think in the lunar lander; terms of specifics rather than packing. gener- - the guidance and control of Exocet alisations. Show me a problem, sign- missiles which are skimming a few feet Please make the chequeor post a solution, and let me demonstrate above the waves in the presence of company order payable to Reed that it works. In this way, I feel noisy sea swell; Business Publishing Group and comfortable and I am happy to take satellite navigation as an 1 - aid to send to Lindsey Gardner, Room more ambitious abstractions on board. precise ship docking and manoeuvre; .L333, Quádrant House,.The Your comprehension of the subject - and tracking radars and the control Quadrant,Sutton SM2 5AS. may fall under one of the following of auto -pilots. _Credit card orders can be phoned profiles: Despite the complexity of the through on 081-661 3614 (1) You already use Kalman filters engineering system, the fundamental .(mornings only). successfully and the terms digital filter, problem remains of how to recover the state variable, mathematical model, characteristics of a deterministic signal autocorrelation, variance, mean - corrupted by stochastic noise. Here square error, and random noise are deterministic means exact or predict- well understood. able, whereas stochastic describes a

320 ELECTRONICS WORLD+ WIRELESS WORLD April 1991 PROGRAMMING process made up of random events. tant to he given a special name - the stochastic. This could be of consider- These appear unpredictable to an probability -density function symbol- able significance to any prospective observer, but can he characterized by ized by p(y). Much of the subsequent population planner anxious to predict statistical methods. I will describe my work will rely on some comprehension future trends. How far back in time experiences when interfacing an Ana- of the terms mean value, variance, and should he go to he confident of his log Devices temperature transducer mean -squared value as a way of figures? In signal -processing terms, this AD5911 to a digital computer IBM PC describing the characteristics of a ran- problem has already been addressed clone, through a 12 -hit a -to -d conver- dom signal. It is appropriate to adver- using a 2 -term moving averager. ter. The signal was deliberately cor- tise the first and second moments of an Instead of processing all the terms, the rupted by random noise before being amplitude distribution for both con- average is computed using a moving processed in real-time through a Kal- tinuous and sampled data signals, as in mean. Because of the small number of man filter written in C. Finally, the the box below. A few words on nota- samples, expect considerable variation processed output was displayed graph- tion will also he relevant. It is custom- in the calculated mean. Clearly, the ically through an EGA card and colour ary to identify the operation of evaluat- variation between samples is an impor- monitor. ing the mean or expected value of a tant parameter in random -signal analy- By way of a comparison, the proces- data set by E. Thus, the mean or sis. This is quantified by statisticians as sed output will be shown with no expected value y is given. by E[yl. the variance. filtering at all, as well as the effects of a To compute the variance, first sub- 5 -term moving averager. Remember tract the mean value from the signal, this is reality, not a game played on a then square the result and evaluate the blackboard where everything works Characterizing stochastic average. With knowledge of the perfectly first time. Be prepared to get noise- Noddies' guide to variance cr2 and the mean value y, the it wrong before you get it right and statistics meat square value learn to try a little harder next time. By Most of us have a good idea of what is deliberately selecting a relatively mod- meant by the average value, but the y2 ran he predicted using y2 = cr2 + est system to control and monitor, it concept of stationarity may not he (y)2. It is interesting that electrical will he possible to see what is going on quite as clear. For example, the mean engineers have been using this result without being overwhelmed by detail or expected value is the usual arithme- for years to compute the total average and complexity. tic average summed over all the sam- power of complex waveforms. Con- To help you to participate fully in the ples, then divided by the number of sider how to evaluate the total average discussion, it is first necessary to intro- samples. How would the mean value be power of a signal made up of a DC' duce a few terms from elementary affected if the sample number were component, together with an AC (or statistics. Fig. 8.1 represents a con- increased? If the statistical properties time -varying) component, developed tinuous random -signal voltage which remain unchanged, then the signal across a 112 resistor. Obviously, the may take any value in the range ±5V, would he characterized as stationary square of the mean value is the power for example. Statistics of a random variable

Continuous signals Discrete signals

Obtaining the mean value from the Average value of signal

amplitude distribution. n , First moment of y a Y = Pmy, Fig. 8.1. Quantifying random signals m=1 Y = Sy P(y) dy using the probability density function. Mean -square value n b To learn a little more about the charac- Evaluating the mean -squared value. y2 = pmy,n2 teristics of this signal, it makes good Second moment of y a jm=1 sense to ask for what fraction of the total observation time To does the Standard deviation 6 is related to 2 signal occupy a particular voltage y2 = P(y) dy the variance by n range? For example, the tram -lines b a- drawn in Fig. 8.1 indicate the time 2 = V'm -592Pm spent in the range Sy and they enable Electrical analogy m=1 us to compute the sum: 0/1+8/2+ 8/3+8t,+ ...) y2=c2+(y)2 q = TO 62 where? is total average power and is average AC power. Examination of this will expression Alternative notation soon make evident that q tends to zero as the observation time To becomes infinite. However, the division of q by E[y21 = or2+E[y]2 Sy as the interval between voltage If the DC component is zero, the variance is equal to the mean -square ranges to zero does tend to a shrinks value. definite limit. This is sufficiently impor-

April 1991 ELECTRONICS WORLD+ WI RELESS WORLD 321 PROGRAMMING

in the DC component, whilst the (1) Evaluate the mean or expected amplitude distribution, using: variance represents the AC power. value Ely]. Examine the relationship closely. (2) Calculate the mean -square value Observe that, when the mean value is E[y2[. E[á.21= zero, the square root of the variance m=I (defined as the standard deviation) is Area under Gaussian curve equal to the root mean -squared value =0.01(0)2+0.03(1)2+0.11(2)2+0.19(3)2 (r.m.$) of the waveform. The noise Y Area y to y+y generators shown in Figs. 8.7 and 8.8 (3 sgt figs) are designed to produce a random - +0.30(4)2+0.20(5)2+0.13(6)2+0.03(7)2 o 0 noise voltage with a hell -shaped dis- 0.5a 0.192 Gaus- =18.13 tribution curve. The theoretical a 0.341 sian curve of a random signal with 1.5a 0.433 The standard deviation is a measure of mean value y is shown pictorially in 1.645a 0.450 the overall spread of the signal about Fig. 8.2. There are some interesting 1.96a 0.475 the mean. It is defined as the square and important points to note about the 2a 0.477 root of the variance. idealised mathematical model, which 2.5e 0.494 2.575a 0.495 in characterizes random behaviour 3a 0.499 2 terms of the parameters y and a. Use a`' Ú',-Y) P,, the normal curve to apply distribution Table 1 in= I scientific method to predict the likely behaviour of apparently unrelated events. =(0-4.01)2x0.01 +(1--3.01)2x0.03

+(2-4.01)2x0.11

+(3 -4.01)2x0.19+(4 -4.01)2x0.30 +(5-4.01)2x0.20 9 9+y Value of variable 9-2a 9 9+2a +(6 -4.01)2x0.13+(7 -4.01)2x0.03 9-3a 9-a 9+a 9+3a Fig. 8.3. Shaded area is related to Voltage numerical values of Table 1. =2.05

Fig. 8.2. Theoretical Gaussian curve for 0.30 Hence, the standard deviation is given random signals normalised in terms of by V2.05 = 1.43 mean and standard deviation. 0.19 0.20 The aim is to verify that the mean - (1) The curve is symmetrical about the 0.13 0.11 square value (total average power) is mean. 0.03 I 0.01 I 0.03 the sum of variance (average AC (2) The probability of a voltage lying 1 power) and the square of the mean between two given values is simply the 0 1 2 3 4 5 6 7' (power in the DC component). area under the curve between the ym appropriate limits (Fig. 8.3). For exam- Fig. 8.4. Eight -level amplitude ple, the area between the mean value y E[v2[ = a2+(EM)2 distribution. and (y + a) is obtained from Table I. So it can he concluded that the prob- (3) Determine the standard deviation 18.13 = 2.05 + (4.01)2 which ability of the signal lying between the a. confirms the anticipated result. mean and one standard deviation (4) Confirm the total average power is a above the mean is 0.341. Because the the sum of the variance (average AC Tracking time -varying signal curve is symmetrical, it follows that the power) and the power in the DC in the presence of noise - probability of the noisy signal having a component. optimal estimation value within one standard deviation Before the characteristics of an opti- each side of the mean will he 0.682. The average value is given by: mum recursive estimator or a scalar (3) The Gaussian curve is almost zero Kalman filter can he established, it is beyond (y + 3a). In other words, the necessary to quantify the measurement probability of the signal being more criterion upon which the best possible than plus or minus three standard m=I estimate of the noisy variable is made. deviations away from the mean is very This problem was investigated almost small. two hundred years ago by Karl A simple example will help you make =0.01x0+0.03x1+0.11x2+0.19x3 Frederick Gauss in connection with the the necessary connections. A noisy prediction of planetary orbits, based on instrumentation signal is sampled by a +0.30x4+0.20x5+0.13x6+0.03x7 noisy or uncertain observations. Gauss 3 -bit a -to -d converter. Analysis of a adopted the method of least squares to =4.01 large number of samples gives the find the best approximation to a func- 8 -level amplitude distribution shown in The mean -square value is obtained by tion from a range of experimental data. Fig. 8.4. evaluating the second moment of the Real-time estimation based on a

322 ELECTRONICS WORLD+WIRELESS WORLD April 1991 PROGRAMMING minimised mean -squared error crite- EI(Y(a)-Y(n))21 rion remained intractable until about 1960, when R. E. Kalman, and others, In doing so, the relationship between demonstrated how the algorithm might a(n) and h(n) will he established, and he implemented recursively. Consider the need to incorporate a model of the the elementary recursive algorithm: signal into the Kalman filter will be demonstrated. The mathematical y(n) = ay(n - I) + bx(n) details are contained in Appendix 1. Here a and b are constants subject to the constraint a + b < 1 to ensure the filter remains stable and well-behaved. Applied optimal control A weighted version of the current input To design a Kalman filter, it is neces- Fig. 8.7. This noise generator, combined .r(n) is being added to a weighted sary to know the characteristics of the with the Fig. 8.6 circuit, provides an version of the previous output y(n - signal and the anticipated values of exercise in Kalman filter design. 1). Provided the values of a and b are signal and measurement noise. A con- chosen carefully, any abrupt or sudden vincing practical example, which changes in the input will he smoothed requires a relatively modest mathemat- out. This will leave only the long-term ical toolkit, is the measurement of +15V trend. Anyone familiar with digital temperature using the Analog Devices filters will have recognised this as a AD590. This 2 -terminal integrated cir- simple first -order low-pass filter, whose cuit transducer produces an output output will "track" or follow a slowly current proportional to absolute changing input signal whilst ignoring temperature (1µA/°K) in the range the high -frequency noise, as in Fig. 8.5. -55°C to + 15(1°C. An attractive fea- v(out)= ture of the data sheet is the thermal v(in)+noise circuit model and the time constants for both the F (metal case) and H (cera- mic) packages (Fig. 8.14). The compre- hensive data sheet also provides a variety of applications circuits. Here, the 2 -trim circuit was selected which gave an output of I00mVí°C over the range 0°C-100°C. The differential Time equation which models the dynamic Real-time Kalman filter characteristics of this transducer is The input to the Kalman filter will be a Fig. 8.5. Elementary first -order low-pass given in Appendix 2, with along the sequence of numbers - actually a digital filter removes HE noise, allowing model showing transformation from string of l's and 0's from the a -to -d - output to follow slowly changing input continuous to sampled data. which represent the noisy transducer signal. output. The operation of the filter will +15V be to process the data sequence in real-time, before presenting the re- This is a useful starting point towards 35.7kn. 2kn 97.6k.n. 5k.n. ordered data to the outside world. To understanding the mechanism of a Kal- simplify the design and description of man filter. However, a couple of small AD581 the digital -signal processing operation, but important modifications need to he it is customary to adopt the graphical introduced. Instead of a and h being . symbols shown in Fig. 8.9. Apart from constants, allow both to he functions of 100mV/°C the time -varying gain block b(n) in the n. So, the recursive algorithm may be 27k AD301AL feedforward loop, the mathematical VT =100mV/°C written as: operation of each symbolic block AD590 should he self-explanatory. 9(n) = a(n) y(n- I)+ b(n).r(n) Correction V- You may have noticed the subtle + y(n) change in notation. The "cap" or "hat" Fig. 8.6. Measurement of temperature Time + Prediction over the y terms are intended to repre- using the AD590. varying sent an estimation. In other words, the gain current predicted output is made up of To complete the hardware description, two weighted terms the previous combine the output the transducer - of T estimate and the current noisy with the random -noise generator measurement. The relative weighting shown in Fig. 8.7, then process through Measurement System Unit coefficient parameter time of each will depend on the confidence the 12 -bit a -to -d AD574A contained on delay the filter places in its own prediction, or the Blue Chip analogue input card in the observation. The next step is to AIP-24, which is conditioned in the Fig. 8.9. System block diagram of the establish the best estimate y(n), in the range 0-I0V. Adapt the circuit shown Kalman filter representing the recursive sense of the minimised mean -square in Fig. 8.8 to overcome any difficulty in relationship 9(n) = ay(n-I) + error, obtaining the 5837. h(n) fx(n) - acy(n -I )/.

April 1991 ELECTRONICS WORLD+ WIRELESS WORLD 323 PROGRAMMING

220 +15V + r- + 2200µ 1000µ 1µ input

>rlTl. + + 470 2200 1000µ

220 -15V 100k SIGNAL NOISE 200k 1M 10k

100k 741 I F-----11- 10k 741 iÍ--,,,' 1µ 10k 741 1jy 10k LLoutput 1k 1i 1k 10k 10k 10k

71

50-5000 Hz WHITE NOISE-Both signal and covery of low-level 500 -Hz signal from noise. quire ±15 V supply, which can be simple volt- noise levels are continuously and Indepen- Circuit gives maximum noise output Into 1500 - age doubler without regulation.-J. E. Morals, dently variable from zero to maximum In simple ohm load; for lower load impedances, reduce Simple Noise Generator, Wireless World, April noise generator developed to demonstrate re - noise level to prevent oscillation. Opamps re - 1977, p 62.

Simplifying the design - the any sudden changes in the input will be using the program, transducer, and steady-state Kalman filter smoothed out. This will leave only the random -noise source are shown in the long-term trend or low -frequency com- screen dumps of Figs. 8.10 to 8.13. The Kalman gain is a time -varying ponent. Additional insight into the parameter whose value cannot exceed smoothing operation is achieved by Listing 1 The unity. magnitude of the gain convoluting the impulse response h(n) reflects the confidence the filter places with an input signal x(n). The time - in the current measurement. When the FIRST -ORDER KALMAN FILTER * extended impulse response is a re- gain is small, the filter is suspicious of minder that many input samples must the new data and places more confide- #include be taken into account when forming #include nce in its prediction. When the gain is the current estimate of the processed #include large, the filter is less dubious of the output. Try cycling a noisy DC signal #define BASE 512 new measurement. As shown in the through the filter and observe how the #define START 0 appendix, the gain is related to the processor establishes trends. main() error covariance p(n), or mean - To understand the reality behind the ( squared error, in this single variable int x,y,j; abstraction of optimal filtering, it is example by this recursive expression: float word,old,new,input; helpful to design and use your own unsigned int lower_bits,upper_bits,flag; p(rl) Kalman filter. The results are really outp(BASE,O); h(n) - quite remarkable. The C program with /* (p(n)+cr2) SELECT CHANNEL graphics advertised in listing 1 imple- 6v2 */ where is the measurement noise ments a linear first -order Kalman filter for(;;) variance. in terms of the characteristics of the ( The recursive nature of the algor- AD590 and the sampling interval T. _seNideomode(_DEFAULTMODE); ithm guarantees that the gain h(n) Use the minimised mean -squared error _setvideomode(_HRES16COLOR); converges to a steady value after very criterion to process the noisy measure- /* initial in EGA MODE few iterations. Ignoring any tran- ment real-time and display the */ sient, it is possible to pre -compute the filtered output on the monitor. The _clearscreen(_GCLEARSCREEEN); steady-state gain using the method incorporation of a delay loop in the _setbkcolor(_GRAY); shown in Appendix 3. This has the data capture routine establishes a sam- _moveto(0,199); effect of reducing the Kalman filter into pling interval of 50ms. This is in agree- _lineto(639,199); a simple low-pass digital filter. The ment with the model and makes the _moveto(0,199); is simply the signal -processing operations observ- _lineto(0,0); processed output /* weighted 4 be a useful sum of the current noisy input able. Appendix should DRAW X 8 Y AXES and the previous output. The careful source of reference when identifying */ choice of coefficients using the methods the relevant parameters in the pro- _settextcolor(3); outlined in the appendix ensures that gram. The results of my experiences _settextposition(4,3);

324 ELECTRONICS WORLD+WIRELESS WORLD April 1991 PROGRAMMING

_outtext("Temperature (0-100) degrees while(32 & flag); /* - Celsius"); lower_bits = inp(BASE+2); TIME WASTE TO MAKE SAMPLING /* upper_bits = inp(BASE+3); INTERVAL 50ms COLOUR AND POSITION TEXT word = ((15 & upper_bits) * 256) + lower_ *1 */ bits; for(j = 0; j <= 20000; j++) for(x = 0; x <= 639; x++) input = word/4095; { { /* } outp(BASE+1,START); RECURSIVE KALMAN FILTER EQn. } /* */ getch(); START CONVERSION new = 0.99 * old + 0.009 * input; /* */ y = 200 * (1 - new); HIT ANY KEY TO REFRESH SCREEN do _setcolor(14); *l { _moveto(x,y); } flag = inp(BASE+3); _lineto(x,y); } } old = new;

Fig. 8.10. Signal (temperature) plus random noise.

. ;N"/'. L

. V % '! R" 1V5.11`i s,",,..5' f r1' , .ti. . ' 1

Fig. 8.11. Effect of a five -term moving averager.

Fig. 8.12. Processing the same signal through a Kalmani filter.

Fig. 8.13. Response of Kalman filter to a step input.

April 1991 ELECTRONICS WORLD+WIRELESS WORLD 325 PROGRAMMING

Appendix thin-film resistors are laser -trimmed to calibrate the device to 298.2µA at 11(z) - z-ak (1) Relationship between a(n) and b(n) 298.2°K (+25°C). Due to its high - impedance current output the device is where a = The aim is to establish the relationship insensitive to voltage drops over long between the coefficients of the recur- wires, making it ideal for remote - To obtain the recurrence relationship, sive algorithm sensing applications. Any well - convert from transforms to sequences insulated twisted pair is sufficient for using: 9(n) = a(n)9(n-I)+h(n)x(n) operation 100's of feet from the con- V(z) k Here the first term is a weighted ditioning circuitry. With reference to version of the previous "best" estimate, Table 8.2, it is possible to model the T(z) z-a dynamic characteristics of the trans- in the sense of the minimised mean - cross -multiplying squared error. The second term is a ducer using the first -order linear dif- ferential equation: weighted version of the current V(z)(z-a) = kT(z) measurement. Enumeration of the by (It error t + v = k(T+w) v(n+ I )-av(n) = kT(n) It e(n) = 9(n)-y(n) allows the mean -squared error to he where t is the time constant of the Expressed in terms of the current in seconds output, this is: written as transducer y is the output voltage in volts El (9(, _%(,,WI T is the monitored temperature in v(n) = av(n-1)+kT(n-1) The two time -varying parameters a(n) degrees Celsius (°C) and b(n) are chosen to minimise the k is the steady-state gain (0.1) w is the random white noise mean -squared error. Write the mean - T(n) V(n) squared error as: Fig. 8.14. Extract from Analog Devices p(n) = El(a(n))1(n-1)+/(n)x(n)-y(n))21 data sheet. Time response of AD590 to a step change in temperature is determined Differentiate with respect to a(n) and by thermal resistance and thermal b(n) before equating to zero: capacities of the chip, Ce.n, and the case O HT al'(n) C. Ceti is about 0.04Wsl°C for the - 2E[a(n)9(n- 1) AD590. Cc varies with the measured aa(n) medium. In most cases, the single time Fig. 8.15. Characteristics of the filter +b(n)x(n)-y(n)19(n- 1) constant exponential curve of Fig. 8.14 is modelled as recursive digital filter. and sufficient to describe the time response. Rather than apply a deterministic a pOi) _ 2Ela(n)9(n-1) input, enquire how this model will a b(n) modify the characteristics of white +b(n)x(n)-y(n)ix(n) Ttln°I noise. With reference to Fig. 8.15, the sampled output can he expressed as: which is a minimum when v(n) = av(n-/)+kw(n-1) a(n)9(n-I)+b(n)x(n)-y(n)=0 ltf) T6) = Tinitial + (Tfinal-Tlnlpnl)tl-° The autocorrelation function of Substitute x(n) = cy(n) to write: r(k) the processed output is computed on a y(n) sample -by -sample basis using: a(n) [1-ch(a)l Tlnlfl°I r '4r Time - v(n-1) Time response curve r(k) = El v(n) .v(n+k)I since When k = 0, the mean -square value of Y(ii) }'(z)- the output noise is: -z - e - y(n-I) )'(z)z-I ' -a The use of the Laplace transforms allows the deterministic transfer func- the required relationship is rw(() = Elv(n)2I tion to he expressed as:

a(n) = al I -ch(a)l = El(av(n-1)+kw(n-I))2l V(s) k

(2) Modelling the dynamic characteris- T(s) st+ I = a2rvv(0)+k2rw,,,(0) tics of the transducer Clearly, the pole is located at s = -lit. This may he written as: The mathematical model is based on Under the z -mapping z = e'T, the pole the Analog Devices AD590 2 terminal is translated from the left-hand stable k " vv(()) -zr,(0) IC temperature transducer. For supply region of the s -plane to a point on the voltages between +4V and +30V, the positive real axis of the z -plane located electrical characteristics are equivalent inside the unit circle, where z = a. The To obtain the autocorrelation function, to a constant -current generator produc- transfer function of the digital system follow this procedure and compute the ing 111A/°K. In manufacture, the chips' becomes: coefficients for k = 1, 2, 3, ... etc:

326 ELECTRONICS WORLD+WIRELESS WORLD April 1991 PROGRAMMING

r,,,.(I)=E[v(n).v(n+1)1 Assume the linear observation model The steady-state gain in achieved by x(n) = cs(n) + v(n) and the dynamic soling the quadratic for h. Of course, = El v(n)(av(n)+kw(n))1 signal model s(n) = as(n - I) + v(n - this result could have been achieved = ar,(() 1). Then substitute and express the recursively simply by deducing (re- mean -squared error as: member a deduction is a scientific Similarly, when k = 2: guess) the initial mean -square error. p(n) = El(a(I -ch(n))e(n- I) As an example let p(n - I) = 11)00. r,(2) = a2r,,,(()) This large value indicates low confide- -(I -cb(n)n'(- I )-b()v(n))21 nce in the deduction, although it does Since the ACF is an even function, the initialise the system and get the filter coefficients are symmetrical about the Because e(n - I), w(n - 1) and v(n) started. Confirm for yourselves that origin, as shown in Fig. 8.16. share no common characteristic, their averaged cross products or crosscor- h(n) approaches thé limiting value h (k) relation coefficients will he zero. after a couple of iterations. 0=0.996 v (4) Identifying the parameters h(n) = a21 I -ch(n)12p(n-1) 0992 0.996 0.996 0.992 0.988 ' 0 988 +[ 1-ch(n )12crw+h2(n)cr,2, As already indicated, the output from the temperature transducer is a linear substituting voltage with a sensitivity of l($)mV/°C. h(l,)61 Since 1(111°C maps to 4095 at the output -3 -2 -1 0 2 3 p() - of the a -to -d (effectively unity after c division in the program), select the and rearranging measurement coefficient c to he 0.01. Fig. 8.16. Effect of digital filter on a The numerical value of the sampled random input may be determined by h(n )(a1,-:+(21a2p(n- I )+aá,1) signal pole is obtained from the autocorrelating the processed output. expression a = e- With a sampling Notice mean -square value is given by = c[a2 p(n -1)+a;,,1 interval of 50ms and a transducer time r,,,.(0). constant of 13.5s, this gives a = 0.9963. Hence the gain of the Kalman filter is Notice from Fig. 8.18 that a Gaussian (3) Evaluating the steady-state gain b(n) given by: noise voltage spends 99.5% of its entire lifetime within three standard devia- c[a p(- I )+cr2,,,1 With the aid of the signal and measure- tions of the mean. h(n) - 2 2, o ment model shown in Fig. 8.17a and the This means that, practically, the overall model of the optimum recursive esti- The object of this unpleasant algebra variation of the noise voltage may he mator in Fig. 8.17b, it is possible to has been to establish the relationship represented by a figure of between four express the mean -squared error as: between the steady-state gain h and the and six standard deviations. Adopt an parameters a and c. Ignore engineering rule of thumb to allow the E1(s(n)-s(n))21 the initial h(n) = transient and assume h(n) has con- standard deviation es to he interpreted as being Vv_v/5. is verged to a steady value b, when the It convenient to = El(us(n-1)+h(n)(a(n)-acs(n-1)) estimate the peak -to -peak noisy vol- mean -squared error is a time invariant. tage be This is represented algebraically as to 5V. In other words, the -s(n))21 variance a2 will he unity. The esti-

p(n) = p(n- I) = p mated noise parameters are c7,,2 = 1 v(n) and aµ2 = I - u2 = 0.00738, which give Measurement The required result using this rela- noise a steady-state gain h of 0.0098 as well w(n-1) tionship is: + Signal s(n) x(n) as a Kalman filter equation:

White e O +© h2(a2ca2,)+h(c2a 2,+cr2[ I -a21)-caK.=O noise + Observation y(n) = 0.9963 v(n - I ) + 0.111198[x(n) data - 0.0(19963 v(n I )1 a s(n-11 Fig. 8.18. Engineering approximation - used to establish, standard deviation of random signal. o - T Fig. 8.17. Models of signal and observation process (a) and optimum recursive estimator-Kalman filter (b).

x(n) Correction + s(n) P(y) Observation Time + Prediction Probability data varying density gain

Measurement System coefficient parameter

April 1991 ELECTRONICS VV'ORLD+WIRELESS WORLD 327 PROGRAMMING

This may he expressed as an elementary first -order low-pass recur- sive filter: - y(n) = 0.99620y(n - I) + 0.01)98x(n) E.I.E Evidently, this is marginally unstable c since 0.99620 + 0.0098 > 1. However, the Kalman filter is robust and

acceptable compromise is to modify the t.. coefficients as shown: «_1

y(n) = 0.99y(n - 1) + 0.0119í(n) W°

Deliberately detpne the filter by adjust- + WIRELESS WORLD ing the coefficients and observe the .,

radical change in the processed output. JANUARY 1931 £1.95 _ Remember that, theoretically, no other estimator can produce a better estimate SCIENCE of the noisy signal. It is a powerful way of proving that Kalman filters really do Electrochemical reduce the effects of noise. It should energy from water? - also give you the confidence to examine more ambitious projects, using signal 1 vectors and matrix theory. DESIGN - 1 High efficiency power conversion

REVIEW f Asyst it the lab: -

help or hindrance? r ter

Nei', E, ^ l'E r '

Eastern bloc ft

telecomms _ -

RADIOCOMMS

TALKING -

References ELECTRONICS WORLD (1) S. M. Bozic. Digital and Kalman Filter- ing. Edward Arnold 1979. FOR £ 1 ONLY (2) G. C. Dean. An introduction to Kalman filters. Measurement and Control. Vol 19. - March 1986. (3) B. Hill. Recursive Kalman Filters. Due to circumstances beyond our control Practical Computing. April 1983. (4) II. J. Hutchings. Linear Systems and there have been difficultes with the Random Inputs. Electronics & Wireless World. April 1988. newstrade distribution of the January issue. (5) Lobdill. Kalman Mileage Predictor- Monitor. Byte. July 1981. Ifyou have not been able to get hold of. (6) P. A. Lynn. An Introduction to the ¡¡- Analysis and Processing of Signals. Nlacmil- your copy please contact Lindsey _Gardner Ian 1982. (7) M. Schwartz and L. Shaw. Signal (mornings only) on 081 661 3614 Copies Processing Discrete Spectral Analysis, Detection and Estimation. McGraw-Hill available for only£1- incl. p & p. 1975.

328 ELECTRONICS WORLD+WIRELESS WORLD April 1991 - Where can you find information about the technologies of the '90s? Our information -packed books will give you the clear view of open systems, PC networking, the electronics industry and the new scanner technology.

_ Hitchhikers' Guide to THE w Cost PC SCANNER tworking ELECTRONICS HANDBOOK IN THE '90s VIII /411 " A a COr,ptele puma to a - de use and apOnpauens o desktop scanned MEI SYSTEM

I M1 Basic 4iY1.B 444 ~Am 'If 3 ...... ,. ._a

aOnslálaners N as L. ' . .-A

OPEN SYSTEMS: LOW COST PC HITCHHIKERS' THE SCANNER THE BASIC GUIDE NETWORKING GUIDE TO HANDBOOK TO OSI AND ITS by Mike James ELECTRONICS IN by Stephen Beale and IMPLEMENTATION THE '90s James Cavuoto The growing Ímpor by Peter Judge by David Manner:: tance of networking has An authoritative and in- A concise, clear guide made this a vital hand- David Manners, senior formative guide to the to this complex area of book for any business editor on Electronics selecting, installing and computer standards, setting up a network or Weekly newspaper. ex- using of scanners. It untrammeled by jargon trying to run one. It plains how the electron- offers practical tips and and with appropriate shows how networking ics industry works, ex- advice, covering in de- and comprehensive revolutionises the way amines its key prod- tail each stage in docu- analogies to simplify we use PCs and the ucts, and discusses its ment production with this difficult topic. tasks that they perform. central role in the '90s. scanned images.

Order Form Please send me the following: Oty Title Unit Price P&P Total Full despatch address/credit card registered address:

Open Systems 12.95 1.00 Name Initials Low Cost PC Networking 16.95 1.00 Position Guide to Electronics in the '90s 12.95 1.00

The Scanner Handbook 19.95 1 00 Company

TOTAL Address Choose one option:

I enclose a cheque for £ payable to Computer Weekly Charge my credit card account £ to pay Computer Weekly Amex Access Visa Diners Postcode My card number is

My card expires on Return to Computer Weekly Publications. Quadrant House. Sutton. Surrey St42 5AS or ring 081-685 9435 and place your credit card order. Bulk prices

Signature on request. Allow 28 days for delivery. Ref: EW 19t . MONITORS IBM KEYBOARD DEALS Superb Quality 6 foot 40u MONOCHROME MONITORS A replacement or backup keyboard, switchable for IBM PC, THIS MONTH'S SPECIAL! PC -XT or PC-AT. LED's for Caps,Scroll 8 Num Locks. Standard : 19'! Rack Cabinets There has never been a deal like this oral 84 keyboard layout. Made by NCR for the English 8 US markets. Absolutely new & m .> s Massive Reductions Brand spanking new & boxed monitors standard. Brand boxed with manual and key o ,. template for user slogans Attractive Ono 6:{T from NEC, normally selling at about on the function keys. Virtually New, Ultra Smart! £1401 belge,grey and cream finish, with the usual retractable legs e> These are over -engineered for ultra Isev . underneath. A generous length of curly cord, terminating In the Less Than Half Price! reliability. 9- green screen composite Input standard 5 pin DIN plug. A beautiful piece clean of manufac- IIITop quality 19' rack cabinets made In UK with etched non -glare screen plus switch - turers surplus. What a deal) £39 (B) 5/£175 (D) ómá by Optima Enclosures Ltd. Units feature able high/low Impedance Input and output see :3+:.+}.' Brand new and boxed 84 key PC/XT type keyboards In standard : evé ;:.;.;_ designer, smoked acrylic lockable front for daisy -chaining. 3 front controls and 6 at rear. Standard BNC e sockets. Beautiful high contrast screen and attractive case with IBM grey with very attractive mottled finish and 'dicky" solid feel 'r s'<:

CIRCLE NO. 1460N REPLY CARD CIRCUIT IDEAS

Low-cost digital phasemeter

To make a phase meter with a typical error of 0.2%. the ICL 7107 digital volt- meter IC can be pressed into service to "Fuse -blown display the phase difference of two signals in degrees. indicator Two LM31 I comparators convert the When the fuse blows, Ledl indicates inputs to cmos-compatible square waves. the fact. Normally, the red led, D1, is in The leading edge of the square at ICI out- parallel with the green led 1)2, the volt- put sets FF1 and removes the inhibit from age drop across DI preventing Ledt FF2, that from U2 setting FF2 which resets from illuminating. A blown fuse FF1, FF2 in turn being reset. Output at Ql removes the current through Led2, the is therefore a pulse whose width is direct- voltage across Led' allowing it to light. ly proportional to phase difference Resistor R=DCin/0.01, unless DCin is between the inputs. 5V, in which case R=47052. Resistors R5 and R6 form a voltage T. Cottignoli divider to provide a voltage reference of Taranto, Italy 1.02V for the ICL7107, the height of the pulses from Q1 being set by R1 and R4 to DC in Fuse DC out 3.6Vrer at position I of the range switch. The average voltage of the pulse train is 0-199.9. For the range set by resistors D1 (3.6Vrer x duty cycle) and the display R12, measurement resolution is 1° over 0- Green reads (1000 x average/vrer), which is 3600 360°. Measurement accuracy is better D2 x phase difference/360°, or 10 x phase dif- than 0.2% over I kHz to 250kHz, falling ference. off at lower frequencies. The decimal point of the display is M.S. Nagaraj D28 D3 bicolour led arranged to give a reading in degrees, so ISRO Satellite Centre that the resolution is 0.1° over the range Bangalore India

.5V z100n 1k 3k9 Vdd V. C ref

1 T100n FF1 Cref

2 REFHI CK1 1999 111 2k2 1/2 CD4013 1R6 1k 700n ICL7107 r-->Set1 05C1

171- Reset 1k 05C --V/ 100k 2 INHI 0.2 +15V LReset2 1 1M OSC3 Dp

D2 FF2 1 lnput2 2 t00n a/2

LM311 CK2 47n IC2 --- !PILO 3 1/2 CD4013 BUFF 1k J - REFLO 470k Set2 CCMMON iNT 20 I Vss I I 220n -15V 1Q *- ''"100n R4 2k 2 I 330 100n -+-

To decimal point

April 1991 ELECTRONICS WORLD+WIRELESS WORLD 331 CIRCUIT IDEAS

Composite -feedback amplifier

An amplifier with a defined output impedance can be imple- being connected between the non -inverting inputs to produce mented rather more easily than in the circuit given by A.J. an amplifier with a floating output giving +24dB with 24V Chamberlain in the October 1989 Circuit Ideas by the use of rails and +I6dB with 6V rails. a modified version of the Howland current -pump circuit D. Austin shown left. Birmingham Voltage feedback to inverting and non -inverting inputs R1A R2A cancels, leaving only current feedback and, therefore, a high output impedance. To produce a specific output impedance, 51k 10k reduce the amount of feedback to the non -inverting amplifier Input input by the appropriate amount. For example, changing R2h -nr----R3 Output to 22kS2 gives a 4,a, of 30052. 30 Two current pumps can he driven in antiphase, a resistor R1B R 2

51k 10k (Z-out=600!1, A=2) 150k

Input R1a R2 R2A 51k 82k Output 30 Modification for floating load Rib R1B R2B

51k 10k (22k) 51k 10k Battery life extender Since primary batteries are usually dis- consequent waste of money and resources reduced battery voltage. carded when their output voltage has is worth considering. The problem is to In this circuit, a TLC3702 comparator dropped below about two thirds of the ini- ensure that the performance of battery - senses V, hen the battery output has tial voltage. any means of reducing the powered equipment does not suffer at a reached a level determined by R t/R,; resistor R3 provides a degree of positive feedback to avoid oscillation. At this ave output the three a Ct point, -gate oscillator driving 74HC4053 capacitive multiplier increases t00n Rt the output to 150% of the battery voltage, 6 12 4 15 R3 which enables the battery to continue in

3 8 service until its voltage has dropped to TLC less than 50%. 3702 74H C 4053 C2 The multiplier is similar to the 7660 10 4 capacitive doubler but, instead of cha ging a capacitor and placing it series with the T 3j l B 13 7 battery, Two capacitors (C1 and C, are charged in series and placed in series with the battery but in parallel with each other. Although the oscillator shown runs at 16 14 -ve around 100k11c. frequency is not impor- 13 4 ?output tant. C, and C, being adjusted to suit.

Ban dg ap 15 1 Efficiency of the circuit is about 90% at r ef. 74 HC 4053 2n1A. falling to 80% at 5mA. Several switch packages can be used in parallel to improve efficiency. Ian M. Wiles hop 3 6 9 10 IPR Technology Basingstoke Hampshire

332 ELECTRONICS WORLD+WIRELESS WORLD April 1991 REAL POWER AMPUFIER For your car, it has 150 watts output. inner tube. Wheels are black, spoked one piece poly carbonate. 13" Superhet Req's PP3 battery. £1.00 ref 80716. Frequency response 20HZ to 20 KHZ and a signal to noise ratio wheel £6.00 ref 6P20, 16" wheel £6.00 ref 6P21. HIGH RESOLUTION MONITOR. 9" black and white Philips tube better than 60db. Has builon short circuit protection and adjustable ELECTRONIC SPEED CONTROL KIT for c5 motor. PCB and all in chassis made for OPD computer but may be suitable for others,' input level to suit youe easing car stereo, so needs no pre -amp. components to build a speed controller (0.95 % of speed). £20.00 ref 20P26. Works into speakers ref 30P7 described below. A real bargain at only Uses pulse width modulation. £17.00 ref 17P3. SURFACE MOUNT KIT. Makes a high gain snooping amplifier on £57.00 Order ref 57P1. SOLAR POWERED NICAD CHARGER. Charges 4 a PCB less thanan an inch square!. £7.00 ref 7P15. REAL POWER CAR SPEAKERS. Stereo pair output 100w each. AA nicads in 8 hours. Brand new and cased £6.00 ref SURFACE MOUNT SOLDER. In easy louse tube. Ideal for above 4ohm impedance and consisting of 6 12' woofer 2' mid range and 6P3. protect £1200 ref 12P18. 1' tweeter. Ideal to work with the amplifier described above. Price per MOSFETS FOR POWER AMPLIFIERS ETC. 00 wan mosfet CB CONVERTORS. Converts a car radio into an AM CB receiver. pair £30.00 Order ref 30P7. pair 2SJ99 and 2SK343 £4.00 a pair with pin out info ref 4P51. Also Cased with circuit diagram. £4.00 ref 4P48. PERSONAL STEREOS Customer returns but complete with a available is a 2SK413 and a 2SJ118 at £4 00 ref 4P42. FLOPPY DISCS. Pack of 15 312" DSDD £10.00 ref 10P88. Pack pair of stereo headphones very good value at £3.00 ref 3P83. We 10 MEMORY PUSH BUTTON TELEPHONES. These are 'cus- of 10 51/4" DSDD £5 00 ref 5P168. also have customer returned units with a built in FM radio at£6.00 ref tomer returns' so they may need sight attention. BT approved. £6.00 SONIC CONTROLLED MOTOR. One tick to start, two tick to 6P34 each ref 6P16 or 2 for £10 00 ref 10P77. reverse direction, 3 click to stop! £3.00 each ref 3P137. 2KV 500 WATT TRANSFORMERS. Suitable for high voltage 12 VOLT BRUSHLESS FAN 4 12" square brEnd new ideal for FRESNEL MAGNIFYING LENS. 83 x 52mm £1.00 ref BD827. experiments or as a spare for a microwave oven etc. 250v AC input. boat, car, caravan etc. £8 00 each ref 8P26. lcd display 412 digits supplied with connection data £3.00 ref 3P77 £10.00 ref 10P93 acorn data recorder ALF503. Made for BBC computer but suitable or 5 for £10.00 ref 10P78. MICROWAVE CONTROL PANEL Mains operated, with touch for others. Includes mains adapter, leads and book. £15.00 ref TRANSMITTER AND RECEIVER. These units were designed switches Complete with 4 digit display, digital clock, and 2 relay 15P43 for nurse call systems and transmit any one of 16 different codes. outputs one for power and one for pulsed power (programmable). VIDEO TAPES. Three hour supenor quality tapes made under The transmitter is cased and designed to hang round the neck Ideal for all soils of precision timer applications etc. £6.00 ref 6P18 kcence from the famous JVC company. Pack of 10 tapes £20.00 ref £12 00 a pair ref 12P26 FIBRE OPTIC CABLE. Stranded optical fibres sheathed in black 20P20. ALARM TRANSMITTERS. No data available but nicely made PVC. Five metre length £7.00 ref 7P29 ELECTRONIC SPACESHIP. Sound and im- complex transmitters 9v operation. £4.00 each ref 4P81. 12V SOLAR CELL 200mA output ideal for pact controlled, responds to claps and shouts and 100M REEL OF WHITE BELL WIRE. figure 8 pattern ideal for trickle charging etc. 300 mm square. Our price reverses when it hits anything. Kit with complete intercoms, door bells etc £3.00 a reel ref 3P107. £15.00 ref 15P42 assembly instructions £10.00 ref 10P81. ULTRASONIC LIGHT. This battery operated unit is ideal for the PASSIVE INFRA -RED MOTION SENSOR. J shed etc as it detects movement and turns a light on fora preset time. Complete with daylight sensor, adjustable lights PHIUPS LASER. 2MW HELIUM NEON (light included). Could be used as a sensor in an alarm system. on timer (8 secs -15 mins), 50' range with a 90 LASER TUBE. BRAND NEW FULL SPEC £14.00 each ref 14P8. deg coverage. Manual overids facility. Com- £40.00 REF 40P10. MAINS POWER SUPPLY KIT £20.00 CLAP UGHT. This device turns on a lamp at a finger 'snap' etc. plete with wall brackets, but. holders etc. Brand REF 20P33 READY BUILT AND TESTED LASER IN ONE £4.00 each ref 4P82. new and guaranteed. £25.00 ref 25P24. CASE £75.00 REF 75P4. ELECTRONIC DIPSTICK KIT. Contains all you need to build an Pack of two PA R38 for above unit £12.00 bubs electronic device to give a 10 level liquid indicator. £5.00 (ex case) of 12P43 SWITCHED MODE POWER SUPPLY (Boshert) +5 at 15A, +12 ref 5P194. VIDEO SENDER UNIT. Transmit both audio and video signals at 3A. -12 at 2A. .24 at 2A. 220 or 110v input Braid new £20.00 ref UNIVERSAL BATTERY CHARGER. Takes AA's, C's, D's and from either a video camera, video recorder or computer to any 20P30. PP3 nicads. Holds up to 5 batteries at once. New and cased, mains standard TV set within a 100' range! (tune TV to a spare channel). SOLDER 22SWG resin cored solder on a 1/2kg reel. Top quality. operated. £6.00 ref 6P36 12v DC op. £15.00 ref 15P39 Suitable mains adaptor £5.00 ref a reel 4P70. ONE THOUSAND CABLE TIES? 75mm x 2.4mm white nylon 5P191 £4.00 ref 600 WATT HEATERS. Ideal for air or liquid, will not corrode, lasts cable ties only £5.00 ref 5P181. FM TRANSMITTER housed in a standard working 13A adapter for years coil type construction mounted on a 4' dia metal plate HI-FI SPEAKER. Full range 131 mm diameter 8 ohm 60 wan 63-20 (bug is mains driven). £18.00 ref 18P10 3'x2' for easy fixing. £3.00 ea ref 3P78 or 4 for £10.00 rat 10P76. khz excellent reprduction. £12.00 ref 12P33. MINATURE RADIO TRANSCEIVERS. A pair of .00 (sT TIME AND TEMPERATURE MODULE, A clock, digital ther- welds talkies With a range of up to 2 kilometres. Units mometer (Celcius and Farenheit (0-160 deg F) programmable too ASTEC SWITCHED MODE POWER SUPPLY. 80mm x 165mm measure 22x52x155mm Complete with cases, £30 00 i I hot and too cold alarms Runs for at least a year on one AA battery. (PCB size) gives +5 at 3.75A, +12 at 1.5A, .12 at 0.4A. Brand new ref 30P12 U £9 00 ref 9P5. £1200 ref 12P39 FM CORDLESS MICROPHONE. Small hand held f Remote temperature probe for above unit £3.00 ref 3P60. unit with a 500' range! 2 transmit power levels reqs PP3 battery. Tun- GEARBOX KITS. Ideal for models etc. Contains 18 gears (2 of VENTILATED CASE FOR ABOVE PSU with IEC filtered socket eable to any FM receiver. Our price £15 ref 15P42 each size) 4x50mm axles and a powerful 9-12v motor. All the gears and power switch. £5.00 ref 5P190. 10 BAND COMMUNICATIONS RECEIVER. 7 short etc are push fit. £3.00 for complete kit ref 3P93. IN CAR POWER SUPPLY. Plugs into cigar socket and gives bands, FM, AM and LW DX/local switch. tuning 'eye' mains ELECTRONIC TICKET MACHINES. These units contain a 3,4,5,6,7.5,9, and 12v outputs at 800mA. Complete with universal or battery Complete with shoulder strap and mains lead. MI magnetic card reader, two matnx printers, motors, sensors and spider plug. £5.00 ref 5P167. £34.00 ref 34P1 loads of electronic components etc (12'x12'eT) Good value at CUSTOMER RETURNED switched mode power suppies. Mixed WHISPER 2000 LISTENING AID. Enables you to hear sounds £1200 ref 12P28. type, good for spares or repair. £2.00 each ref 2P292. that would otherwise be inaudible( Complete with headphones. JOYSTICKS. Brand new with 2 fire buttons and suction feet these PUMP. Fits any drill and is self priming. £3.00 Cased. £5.00 ref 5P179. DRILL OPERATED units can be modified for most computers by changing the connector ref 3P140. CAR STEREO AND FM RADIO. Low cost stereo system giving etc. Price is 2 for £5.00 ref 5P174. PERSONAL ATTACK ALARM. Complete with built in torch and 5 watts per channel. Signal to noise ratio better than 45db, wow and QUALITY PANEL METERS. 50uA movement with 3 different mirror. Pocket sized, req's 3 AA ballenas. £3.00 ref 3P135 flutter less than .35% Nog earth. £25 00 ref 25P21. vanity scales that can be brought into view with a lever! £3.00 each ref LAMP .45 VOLT? only £5.00 ref LOW COST WAUKIE TALKIES. Pair of battery POWERFUL SOLAR CELL 3P81. 5P192 (other sizes available in catalogue). operated units with a range of about 150'. Our price t,J CAR IONIZER KIT. Improve the air in your car! clears smoke and of a solar cell, special DC motor, £8.00 a pair ref 8P50 1^I SOLAR PROJECT KIT. Consists helps to reduce fatigue. Case required. £12.00 ref 12P8. fan etc plus a 20 page book on solar energy! 7 CHANNEL GRAPHIC EQUAUZER plus a 60 waft plastic and turntables METAL DETECTOR. Fun light weight device for bur- Price is £8 00 ref 8P51. power amp! 20-21KHZ 4-8R 12-14v DC negative earth. Cased. £25 ied treasure! 33" long with tune and fine tune controls 10 x resistors) all 1/4 wan ref 25P14 RESISTOR PACK. 50 values (500 2% £10.00 ref 1OP101. metal film ref 5P170. NICAD BATTERYS. Brand new top quality. 4 x AA's £4.00 ref £500 6V 10AH LEAD ACID sealed battery by yuasha ex CAPACITOR PACK 1. 100 assorted non electrolytic capacitors 4P44 2 x C's £4.00 ref 4P73, 4 x D's £9.00 ref 9P12. 1 a PP3 £6.00 equipment but in excellent condition now only 2 for rot 6P35 £2 00 ref 2P286. £10.00 ref 10P95. TOWERS INTERNATIONAL TRANSISTOR SELECTOR CAPACITOR PACK 2. 40 assorted electrolytic capacitors £2.00 12 TO 220V INVERTER KIT. As supplied it will GUIDE. The ultimate equivalents book. Latest edition £20.00 ref ref 2P287. handle up to about 15 w at 220v but with a larger transformer it will lighter 20P32. QUICK CUPPA7 12v immersion heater with lead and cigar handle 100 watts Basic kit £12.00 ref 12P17. Larger transformer ref 3P92. CABLE TIES. 142mm x 3.2mm white nylon pack of 100 ref plug £3.00 £3.00 ref 12P41. £1200 . 50 red lads, 50 green leds and 50 yellow lads all 5mm 3P104. Bumper pack of 1,000 ties £14.00 LED PACK VERO EASI WIRE PROTOTYPING SYSTEM. Ideal for design- £8.00 ref 8P52 ingprojects on etc. Complete with tools, wire and reusable board. BUILD AN IBM COMPATIBLE Our price £6.00 ref 6P33. 12 " HIGH RESOLUTION MONITOR. AMBER SCREEN MICROWAVE TURNTABLE MOTORS. Complete with weight BEAUTIFULLY CASED NEEDS 12V AT /A TTL INPUT (SEP PC ! wou lit ng time. Ideal for sensing electronics that have varied the cooki SYNCS). £22.00 REF 22P2. window displays etc £500 ref 5P165. AT 12 meg turbo 286 mother board. £115.00 pc1 SIC SWITCHED MODE POWER SUPPLY. 220v or 110v input RADIO CONTROLLED CAR. Sigle channel Ric buggy with for - 1 meg memory for above board. £55.00 pct giving 5v at 2A, +24v at 0.25A, 12v at 0.15A and .9Cv at 0.4A£12.00 wart) reverse and rum controls, off road tyres and suspension. 4 meg memory for above board. £214.00 pc3 ref 12P27. £12.00 ref 12P40. AT keyboard £49.00 pc4 CAMERA FLASH UNITS. Require a 3v DC supply to flash. £2.00 FERRARI TESTAROSSA. A true 2 channel radio con rolled car AT power supply and pc case (complete) £115.00 pas each ref 2936 or 6 for £10.00 ref 10P101 (ideal multi -flash photog- with forward, reverse, 2 gears pbs turbo. Working headlights. AT controller card with 2 x serial, 1 x parallel raphy). £22 00 ref 22P6. Floppy and hard controller + mono TELEPHONE AUTODIALLERS. These units, when triggered will SUPER FAST NICAD CHARGER. Charges 4 AA nicad's in less Display driver. £74.00 pc6 automatically dial any telephone number. Originally made for alarm than 2 hours' Plugs into standard 13A socket Complete with 4 AA 1.2 meg 3 12' disc drive. £74.00 pc7 panels. BT approved. £12.00 ref 12P23 (please state telephone no nicad batteries £16.00 ref 16P8. 1.44 meg 5 1/4' drive. £66.00 pc8 req'd). ULTRASONIC WIRELESS ALARM SYSTEM. Two units. one Amber monitor 12'. £99.00 pc9 25 WATT STEREO AMPUFIER ic. STK043. With the addition of a sensor which plugs into a 13A socket in the area you wish to 40 meg hard disc. £270.00 pc10 a handful of components you can build a 25 wan amplifier. £4.00 ref protect. The other, a central alarm unit plugs into any other socket 100 meg hard disc. £595.00 poll 4P69 (Circuit dia included). elsewere in the building. When the sensor is triggered (by body MINATURE DOT MATRIX PRINTER assembly 24 column 5v movement etc) the alarm sounds. Adjustable sensitivity. Price per minimum system consisting of mother board, 1 meg of memory , (similar to RS type). £10.00 each ref 10P92. pair £20.00 ref 20P34. Additional sensors (max 5 per alarm unit) case, power supply, 1.44 meg floppy, interfaces, and monitor is UNEAR POWER SUPPLY. Brand new 220v input +5 at 3A, .12 inc VAT (single mono £11.00 ref 11P6. £525 00 drive 286) pc12 at 1A, -12 at 1A Short circuit protected. £12.00 ref 12P21. £795.00 inc VAT (40 meg + floppy + mono pc13 TOP QUALITY MICROPHONE. Unidirectional electret con- 286) MAINS FANS. Snail type construction. Approx 4'x5' mounted on a denser mitt 600 ohm sensitivity 16.18khz both in chime complete metal plate for easy fixing. New £5.00 5P166. 1991 CATALOGUE NOW IF YOU DO NOT with magnetic microphone stand and mic clip £12.00 ref 12P42. AVAILABLE POWERFUL IONIZER KIT. Generates 10 times more ions than HAVE A COPY PLEASE REQUEST ONE WHEN ORDERING WASHING MACHINE PUMP. Mans operated newpump. Not self commercial unitsl kit including case £18.00 ref 1 8P2. Complete priming £5.00 ref 5P18. OR SEND US A 6"X9" SAE FOR A FREE COPY. MINI vrith ferrite aerial and tuner. RADIO MODULE. Only 2' square IBM PRINTER LEAD. (025 to centronics plug) 2 metre parallel. GEIGER COUNTER KIT. Complete with tube, PCB and allcompo £5.00 ref 5P186. FIX MAINS CONNECTOR. Ideal fort he fast connection of nents to build a battery operated geiger counter. £39.00 ref 39P1 QUICK FM BUG KIT. New design with PCB embedded coil. Transmits to mains equipment. Neon indicator and colour coded connectors any FM radio. 9v battery req'd. £5.00 ref 5P158 BULL ELECTRICAL) £7.00 ref 7P18. COPPER CLAD STRIP BOARD. 17' x Col .1" pitch hero' board. N SOUND DECODER. Nicely cased unit, mains powered 8 PORTLAND ROAD HOVE £4.00 a sheet ref 4P62 or 2 sheets for £7.00 ref 7P22. channel will drive a small speaker directly or could be fed into HI Fl 250 TOOL £2.00 ref 2P352. etc. Our price £12.00 ref 12P22 BN3 :'' STRIP BOARD CUTTING SUSSEX 50T DEPT Ell ref 60P2 COMPOSITE VIDEO KITS. These convert composite video into 3 1/2" disc drive. 720K capacity made by NEC £60.00 5 watt magnetically screened 4 ohm 55 x separate H sync. V sync and video. 12v DC. £8.00 ref 8P39. TELEPHONE 0273 203500 TV LOUDSPEAKERS. SINCLAIR CS MOTORS. 12v 29A (full load) 3300 rpm 6'x4. 1/4' TERMS: PO CHEQUE 125mm. £3.00 a pair ref 3P109. ''MAIL ORDER CASH OR magnetically 0/P shaft, New. £20.00 ref 20P22. TV LOUDSPEAKERS. 3 watt 8 ohm screened 70 TH; ORDER PLUS £2.50 POST 50mm £300a pair ref 3P108. As above but with htted 4 to 1 ink ire reduction box (80orpm) and ...:::...:: toothed nylon belt drive cog £40.00 ref 40P8. VISA TOROIDAL TRANSFORMER. 24v SA encapsulated 4" dia £5.00 SINCLAIR C5 WHEELS 13" or 16" dia inck/d.ng treaded tyre and FAX 0273 23077

CIRCLE NO. I47 ON REPLY CARD April 1991 ELECTRONICS \\ ORLD+ WI RELESS WORLD 333 CIRCUIT IDEAS

PLE5P0 And/or Precision gate array 16 5V Vcs

pulse -width Enable IA generator TR Programmable pulse generators common- A3 ly have limited programming capability ICI by and exhibit initial timing error caused OP lack of synchronism between the input trigger and the system clock. The circuit described overcomes these disadvantages. No RC timing is used and accuracy is solely dependent on clock frequency; a 1 wide range of pulse widths is obtained by G changing the clock frequency. 9 20-5V A PLE5P8 programmable logic element Reset JCLR Vcc D1 08 by Monolithic Memories and a 74273 - a1 Dg - the the octal latch compose circuit; clock IC2 '-Trigger á7 input to the 74273 may be the system a374273 Qy -Output clock. Four of the five inputs to the PLE 03 D6 04 05 are used for state -incrementing control, 114 Q5 -Output the fifth serving as the trigger. The clear r-,{GND CK IT-Clock input of the latch functions as the reset input for the generator. Both active -high and active -low outputs are available. When the trigger goes low, the true out- put of the generator goes high and begins to time-out the programmed n clock cycles; after one complete cycle. the true output goes low. In the case of re -trigger- CLOCK

ing, timing continues for another n cycles f1 and, if re -triggering continues, so does the TRIGGER output tinting. OUTPUT Count cycle In the circuit shop+n. from I to I(, clock -- cycles can he programmed at any desired frequency, and a PLD with more inputs OUTPUT 3-f will allow a greater selection of tinting Retrigger mode combinations: a PLD with nine inputs will TRIGGER I1 give 1 to 256 clock cycles, one input ff I 1 being used as the trigger input. OUTPUT Count cycle Count cycle V.Lakshminarayanan -

Centre for Development of Telentatics OUTPUT l3anga lore 1 India

12 V 12V

High frequency switch 1k An emitter follower can be used as an RF switch, which will work To CMOS TT L at VHF, with a high switching speed. (control input ^ control input Transistor Trt is an emitter follower and Tr2 á current switch. A Output 47l iBC547 voltage of OV at the control input cuts off Tr, and therefore D1, allowing Trl to function as an emitter follower. When the control voltage is 12V, Tr2 is on, Dl conducts and cuts Trl off, preventing

signal reaching the output. Attenuation in this condition is greater Control input (CMOS) 5082/2B00 than -30dB at 80MHz. The control input is cmos-compatible, but OV=switch is on Tr2 or 8,1234/4off the circuit shown right can be used to make the circuit usable for BC547 TTL input. D.I Malynovsky Editorial survey: use the information Leningrad USSR card to evaluate this article. Item L

334 ELECTRONICS WORLD+WIRELESS WORLD April 1991 USE YOUR SCOPE AS A SPECTRUM ANALYSER FOR JUST £295

j¡lilüiu _.. t :I - Imagine, if you will, an '-+ instrument which offers the 01)--z__-I- - power of a spectrum analyser combined with the=ease of use 'IQ :1 of a conventional oscilloscope \\\ _ Tr, , í I /,r probe. Hard to imagine? Not < ® - any more. The Type 107 O y ` A +`+ _,,. Spectrum Probe from Laplace Instruments provides these , . - iw iS _ . - ' ' facilities at a mere fraction of `. i ' r ll 8 t the cost of a fully-fledged .s= -' : I - ' spectrum analyser. ' _ S) IZ -r7- '_-PI .4. _2.," f ..w. Á .1- '11111k II r ` II._ F

Specifications. Laplace Instruments quote the following The Type 107 Spectrum Probe allows any standard oscilloscope specifications for the Type 107 Spectrum Probe to be used as a 100MHz spectrum analyser; the vertical deflection indicates amplitude (on a logarithmic scale) while the FREQUENCY RANGE: 100MHz horizontal scale gives a (linear) indication of frequency. DYNAMIC RANGE: 50dB rrin. Mike Tooley reviewed the Laplace Instruments Spectrum Probe VERTICAL OUTPUT: 5mV/dB typical in the November 90 issue of Electronics World+Wireless World. VERTICAL LOGARITHMIC LINEARITY: ±3dB This is what he had to say: "The ability to display signals in TANGENTIAL SENSITIVITY: 10011V ±3dB at 50MHz the frequency domain on a conventional low-cost FLATNESS: ±2dB, 5MHz to 100MHz oscilloscope should not be underestimated. Indeed, it LF DEGRADATION: Approx. 5dB down below 1MHz should be stressed that the Spectrum Probe can display SPURIOUS RESPONSES: Generallly -40dB signals at 100MHz far outside the bandwidth of, for example, IF BANDWIDTH: 180kHz at -3dB a 10MHz oscilloscope." MAX CW INPUT: +15dBm, 1V at 100MHz SWEEP RATE: 6ms/100MHz typical Our magazine is pleased to be able to offer the Spectrum Probe HORIZONTAL LINEARITY: ±10% to its readers for just £295, £45 off the normal price. To order RADIATION (FROM PROBIE TIP): -40dBm at 150MHz yours, simply fill in the coupon below and return to Lindsey POWER SOURCE: 220V ±10% 50Hz 4W max. Gardner, Room L333, Quadrant House, The Quadrant, Sutton, SIZE: 190 x 25mm diem. (probe) Surrey.SM2 5AS. Alternatively phone in your order on 081-661 WEIGHT: 56gm (probe) 260gm (power supply) 3614 (mornings only). r SPECTRUM PROBE ORDER FORM Spectrum Probe analysing transmitter RF output. for harmonics Please send me the special offer instrument,) enclose a cheque for £339.25 (inc VAT) payable to Reed Business Publishing Group

Please debit my credit card Access, Visa, American Express, Diners Club

Card No : I I I 11 11 I I I I 11 11 11 11 11 11 11 11 11 1 11 11 11 11 1

Expiry date I To the sum of £339.25 II I I IF I

Daytime telephone number: -

Name Mr/Ms (with initials)

Address

r r=w

Signature

J CONSUMER ELECTRONICS

AUTOMOTIVE AUTOMATION PART 2

>< Vn y "~- yy7 c---- - /

c-- S°' _ . . i _. . 9,

0 yr^.1!¡ 426 GTO r , ,_ -

ehicle management and "drive- ABS operates by sensing the onset of ahlility" is the growth area for wheel locking with a rotation sensor, usu- electronic systems. Features and The car makers have ally a reluctance probe and toothed wheel. facilities which were not cost- The control system momentarily releases effectively achievable even as options by always been able to the brake at the offending wheel by trig- other means are becoming the standard. produce a product gering an electro -hydraulic actuator to which could move as "tight" the driver with opposing hydraulic Brakes. The most significant develop- pressure. This gives a disconcerting "puls- ment must he anti -lock brakes, but trac- fast as their marketing ing"through the brake pedal which, in the tion control. adaptive suspension, four- departments wanted. best electronic tradition of dressing up a wheel steering, climate control and other Electronics has given hug to look like a feature. is claimed to secondary safety systems are all now give the driver positive indication that the available. Secondary safety features are the motor industry system is working. Most systems are those which make the car easier to drive something else to sell three -channel, with separate speed sensors or save the driver from himself. It is on. By Tom Woodford. on each wheel. but with the rear wheels arguable that ABS leads to more danger- sharing an "unhraking" valve. ous driving, as it enhances the belief that Knowledgeable road testers in the one is invincible. motoring press claim that a skilled driver

336 ELECTRONICS WORLD+ WIRELESS WORLD April 1991 CONSUMER ELECTRONICS

can always outperform an ABS system in Much research has been conducted to hack -to -hack tests, but we are not all determine the correct differential tempera- skilled and it is the unexpected situation 'The imaginative tures to foot, chest and face level to pre- When tired at the end of a long day that engineer can add all vent drowsiness and some systems con- kills you: similar arguments have applied tain very sophisticated processors to for years to automatic gearboxes. sorts of nice touches. ensure that these differentials are main- Ford pioneered ABS as a standard fit- On the Ford Granada, tained. ment to all current Granadas, using the the rear screen wiper ís Alfred Teves system. Bosch and Honda Four -si heel steering is verging on the offer similar systems, which are becoming automatically started if "gimmick" category, although it is standard equipment on most upmarket reverse gear is selected claimed to otter dramatic stability benefits executive cars. when front wipers in high-speed lane changing or swerving the manoeuvres. In this case, the rear wheels Traction control is an interesting inte- are on. The 7 -Series are turned in the same direction as the grated -system concept. The ABS wheel BMW will switch the front ones: low -speed manoeuvres (park- rotation sensors are used to detect the wipers to intermittent ing) are enhanced by turning the rear onset of wheelspin under hard accelera- wheels in the opposite direction. tion, the control system then applying the when the vehicle is Mitsubishi, among others. have demon- brakes and/or reducing engine power to stationary to avoid strated complex processor -controlled sys- maintain directional stability. nasty squeaking noises' tems operating hydraulic rams to steer the This concept was taken to extreme on rear wheels. Numerous sensors are used the Porsche 959 supercar, where the elec- for the system to determine which way to tronic systems also operated sophisticated steer in any set of circumstances. Since clutches to direct power to the wheels Honda have now introduced a very sim- with most grip at all times. A heuristic esting by comparison. Less sophisticated, ple, purely mechanical system, it is system, the processor could "learn" the but still numerous sensors monitor vehicle unlikely that the electronic systems will operating characteristics of the car to dif- movement and driver demand. The system have a long production run. ferentiate between tyre slip due to pres- processor triggers fast -acting valves on sure differences and genuine wheelspin. otherwise conventional spring/damper Bus -bar systems are. perhaps. the most This system is not quite smart enough. units to increase suspension damping significant sensible application of simple however. as the driver must operate a front "soft- to "stiff- (or `sport") when electronics in a vehicle environment. The switch to tell the controller if the road sur- required. Transition is achieved in less wiring loom of a modern car, in particular face is ice, snow or loose gravel. than IOnts and such systems offer up-market models laden w ith options, improved ride comfort without the penalty contains around 25-35kg of copper. An Active suspension. Seen on Lotus and of roll and float associated with soft sus- obvious solution is already used in mod-

Williams Formula I cars. fully active sus- pension. Manual override is usually pro- ern aircraft. in which a bus -bar feeds pension was also demonstrated by GKN vided for the keen driver to select the firm power to individual ancillaries. which are in a fully -hydraulic system some twenty setting when required. The systems switch attached to the bus where required and years ago. The car's conventional springs automatically from soft to firm at pre- contain a data decoder with a unique and suspension are replaced with Last -act- determined road speeds to maintain vehi- address code. The controlling switch or ing hydraulic rants. A whole range of cle stability. Extensions to this principle processor is also attached to the bus where accelerometers monitor vehicle movement use Hoge self -levelling spring/damper required, and sends the "on" or "off" in three planes on two axes. further sen- units to lower ride height by 10-20ntnt at instruction preceded by the identity code sors monitoring steering angle and verti- high speed to improve aerodynamic sta- of the add essed device. cal loads at each wheel. The processor bility. Such a data multiplexed system has then computes the required position for been shown to save some 30%-40% of each w heel and commands the suspension Hydractive suspension is Citroen's pro- copper weight alone, and at today's metal rants to stove accordingly. Processing and prietary semi -active system and goes one prices is highly cost-effective. Significant electro -hydraulic demands are quite stag- stage further than demand -adjustable further benefits are available in produc- gering, needing a 32 -hit processor running damping by using an additional, electri- tion. for adding options to order as the car at 20N1Hc. cally switchahle hydro -pneumatic spring. is assembled. Similarly, the addition of Advantages in adhesion and stability The system not only increases damping aftermarket options is greatly simplified. are equally dramatic: the car can he tai- but also increases spring rate when need- It also offers some potential for the owner lored to provide any desired handling ed. This otters further improved high- to "customise" the control layout to per- characteristic - it can even he pro- speed cornering stability. sonal preferences. grammed to lean into (instead of away Although suitable multiplex communi- front) kends. Cost will keep such systems Climate control may not seem as glam- cations protocols and hardware already in the "of interest" league. unless there is orous as ABS or ETC. but is still a signifi- exist, such as the I2C bus. the hostile a sudden world shortage of steel springs. cant secondary safety feature, again vehicle environment precludes consumer It is significant that none of the FI teams becoming integrated with other in -car sys- ICs. Conversely, the 1553 avionics bus is now use active suspension. Nevertheless, tems: for example. to direct all air to the somewhat of an overkill. Cars with limit- as a demonstration of what is now achiev- windscreen until the engine is warm, to ed bus systems are already on the market able by electronically controlled mechani- avoid cold feet. More importantly, it sig- and the development of totally integrated cal systems in consumer applications this nals the engine management system as the vehicle control will depend on the exten- is a phenomenal development. air-conditioning compressor is engaged. sion of multiplex control to the whole car. so that the idle speed can he increased to To meet the CARl3 monitoring require- Semi -active suspension is merely inter - compensate for the sudden engine load. ments will otherwise he impossible.

April 1991 ELECTRONICS WORLD+WIRELESS WORLD 337 CONSUMER ELECTRONICS

Instruments. ing first checked with the owner's diary \lost dashboards have sported an "elec- Citroen produced an for a free date. tronic tachometer since the late 1950s. with a capacitor -diode network to convert example of the Entertainment, information and the frequency of pulses from the contact - navigation breaker to a voltage for meter deflection. "ultimate safe car". It The very first in -car electronics were pre- \lost manufacturers have flirted with was made of glass and war valve radios. which used vibrators to "electronic'' displays and many have dis- generate the I -IT (that will not mean the covered that. in Europe at least. drivers had a nine -inch spike saute to younger readers) and occupied prefer traditional. round. analogue instru- most of the passenger's foot -well. where ments.. One wonders if the new monitor- sticking out of the they also served as a heater. Now. they ing systems will eliminate all but the accept a cartridge of CDs. and occupy speedometer from dashboards of the late middle of the steering most of the boot instead. 1990s. wheel. The theory was In -car entertainment is well known to PCB sub -assemblies have been used for most car owners and needs little further instrument panels for some years and the that no-one would risk comment. Most line -fit ICE systems have traditional Bowden -cable speedometer acceptable performance. only let down by and odometer drive has been replaced by an accident in such a playing through six or ten speakers. none a toothed -wheel magnetic transducer. of which costs more than 40p. "electronic" meter and electromechanical vehicle The Philips/Renault ICE controls. with pulse counter. The latest Rolls-Royces full remote operation available from a col- have made the radical break with tradition umn stalk. should he made compulsory as by using a fluorescent display to indicate BMW have pioneered the `"intelligent a safety contribution long befo e monitors gear selector position. odometer'', which offers the driver a led to detect fluorocarbon leaks from the air - Crude monitoring systems. in particular bar -graph to indicate when the next ser- conditioner. for bulb failure. use discrete logic or a vice is due. This system monitors the driv- Much has been made of the new RUS dedicated consumer microprocessor to ing style. car duty cycle and other wear - system in the UK. While invaluable to detect breaks in circuit continuity. relevant parameters to provide the user motorists for its automatic re -tuning capa- Primary safety systems are still some with genuinely useful information. A sec- bilities. the traffic information service way in the future. It is also doubtful if ondary benefit. for the dealers. is that the facility will become intimating for motor - they will gain user acceptance without customer must visit a BMW service centre wary and trunk route users. Automatically legislative compulsion. to have the lights re -set. This helps to re -tuning the radio to local stations broad- maintain brand loyalty. casting traffic information. it will be real- Servicing and reliability In theory the slid-I990s car. equipped ly useful to hear about major local con- Most of the current engine management with the full CARB compulsory monitor- gestion problems that one is by-passing at systems have diagnostic sockets, which ing system. could detect a fault. order its 70m ph. The French system, of logy power can be attached to an analysing computer own spare parts using a data link over the transmitters on a common network. offers by the servicing dealer to check vehicle car's eellphone. then telephone to book a only Autoroute-related information on a performance. service appointment with the dealer. hav- single national frequency. This is close to the original BBC CarFax FIX1-capture con- cept. which would have been highly suc- cessful had it not been killed off by set - makers' vested interests in rival systems. Navigation systems. such +as the 131aupunkt Travel Pilot. are now becoming commercially available. Offering a nuly- ing-neap display. they will guide the driv- h - er to a destination previously entered. `^ Linked to police or motoring organisation r 3 traffic information services. such systems 41,71.4. "aiiiÉl... t".. t offer the possibility' of detours to avoid f 41414.041s. .'.,.'r congestion or the 1\125. Basically inertial guidance computers using maps stored on Cl) ROM, such systems may be overtaken :1 ' ' ` by more recent developments using the ' ^' American. satellite -based global position- + k , L Y' f. ing system (GPS). !'! . 1.1' "4 .r , oí' ., S. Toys from the marketing - , 'r i w. 1 Y,..1 J:J_ department '' EA1 9 V " ' I low useful you find a trip computer o . ti n ...4.1P1. depends on how often you get bored on '': e,G+' _ u.r.á u% rry R?1' \125. ' '' ,i, ó the a.. Some trip computers are obviously '1 , ,..:.o urc.' ;;k;: , included to fill up a hole in the dash. The ;fi - ° =.t.` ' a '. device provided a Rover 80(1 -f n ' on does n clever things like pick up the sum of fuel

;x ELECTRONICS WORLD+WIRELESS WORLD April 1990 CONSUMER ELECTRONICS injected from the engine management sys- What is needed for the future is a differ- 25- tem and use it to display. very accurately. ent approach, measuring what is actually how much fuel you have used since you happening inside the engine, instead of 20 last remembered to reset it. This informa- only external symptoms. This will require tion is virtually useless unless you know the further development of existing sen- the exact capacity of the fuel tank and sors. One approach is to measure the have a calculator with you. since the cylinder pressure during the combustion answer you want is how much fuel is left, cycle; this. among many other things, or (better still) how many miles to empty. being a di ect measure of the combustion -5 t t r I Similarly. many of these devices otter an process. This concept was explored by 200 400 600 800 "arrival time" function. If the ETA were Christopher Clarke and Peter Wihherley crank angle (degrees) calculated on average journey speed this of the leading independent consultancy in would be helpful,hut calculating from this field. Ricardos. They evolved a com- Fig. I. Measurement of cylinder pressure instantaneous current speed gives a silly plex algorithm to predict several critical during combustion cycle for a typical answer, with an ETA in the year 2000 performance criteria front direct cylinder every time you stop at traffic lights. pressure readings taken from an engine Some convenience functions are much over the relevant part of a cycle. 24 more useful. The PLIP remote infra -red Figure 1 shows example cylinder -pres- 22 central locking system is helpful in the sure diagrams measured directly on a 20 dark or when the keyholes have frozen Ricardo test engine. Predicted results were over. If you use your universal "learning" made for air -fuel ratio, EGR, unburnt 18 domestic remote control to store the key's hydrocarbons, CO, NO,, and CO, and 16, IR stream you can unlock the doors front plotted against measured data. Figure 2 14 200 yards away. This French system uses shows the air -fuel ratio result, and Fig.3 12 dedicated ICs hard -coded with a digital the CO, plot as examples. The correla- sequence. In theory vastly more codes can tions are remarkably close. hut exhibit 10 0 2000 4000 6000 be accommodated than is achievable with significant "noise" or scatter, possibly due cycle number conventional metal keys. to errors in the prediction algorithms and (data sets cc18-26.31-36) Once he has access to control signals to cycle -to -cycle in the various measured from other vehicle systems, the imagina- parameters. Nevertheless this is an ideal Fig. 2.Electronics isn't perfect: measured tive engineer can add all sorts of nice DSI' application. Although the cylinder variations between predicted and touches. On the Ford Granada, the rear pressure sensors would be generating data measured airl¡uel ratios in a Ricardo screen wiper is automatically started if at a very high rate. this would be well reverse gear is selected when the front within the capability of current digital sig- wipers are on. The 7 -Series BMW will nal processors. switch the wipers to intermittent when the Ricardos' proposed outline of a closed - vehicle is stationary to avoid nasty loop EMS using these techniques is squeaking noises: the intermittent wipe shown in Fig.4. A system along these rate is also speed dependent and increases lines is not currently commercially feasi- as the faster. When reverse is ble. since the necessary pressure sensors car goes 1100 in prototype o selected the passenger's door mirror is are only available quantities .0 dipped down a tew degrees so the driver and prices. Further research needs to 1060 can see the kerb when parking. prove the validity of the predictive algo- 0 2000 4000 6000 Many executive saloons have an elec- rithms under wider operating conditions. cycle number tronic timed delay on the interior lights so but the overall technique looks very (data sets cc18-26.31-36) that they stay on after the car is entered promising as a significant step towards the and are cancelled as soon as the engine is more stringent EMS requirements of the started. The Rover 400 goes one better mid 1990s. One further problem is the Fig. 3. Differences between predicted and fades the lights out gently, proving physical space needed to locate the new CO, exhaust gas levels in a research that the miracle of electronics has indeed sensors with adequate access to the com- engine had a hand. bustion chambers, since modern cylinder to engine heads are totally devoted multiple EGR is adequate O The real future valves and spark plug: if there ignition (x4) While the marketing men find really use- need a way will doubtless be found. It O fuelling (x4) O for the may he significant that at least one major ful things like interior light faders O electronics engineers to design; the engine manufacturer has already incorpo- cylinder engine predic ion pressure advances made in engine management rated a provision for cylinder pressure mar.agement algorithm (x4) appear slow and ponderous by compari- sensing in their next -generation engine system (x4 son. As yet, no true closed -loop or feed- designs. AFR(x4) EGR feedback back control techniques are used. Current Nox(x4) References variables systems function only as extremely NC (x4) I. \ibberley. t'. and Clark, C.A.. Ricardo co (x4) sophisticated open -loop set -point genera- Consulting Engineers. Ltd. "An investigation of 11 existing EGO sensor feeback tors, based on a small sample transposed cylinder pressure as feedback for control of engine speed load a run. Sensors internal combustion engines. -SAE 119+1396 . to all units in production air mass flow rote, etc. initiate corrective action only when oper- ating parameters are obviously' exceeded. Editorial survey: use the information Fig. 4.Ricardo engine management such as knocking or detonation. card to evaluate this article. Item M system based OSP using the results of

April 1991 ELECTRONICS WORLD+WIRELESS \1ORLl) 339 LETTERS

Back to the future about the propagation of life. Trans I would like to take issue with the Kidd's prototype. encased in a I read with interest the article on Am Phil Soy. Philadelphia. Dec following points: wooden box suspended by a Kevlar Benjamin Franklin in your February 1966. vol 56. part 9 p.74. You suggest that Unix software is Cord front an overhead beam. issue (Pioneers: Benjamin Franklin 2. Gruman. op cit. p.84 expensive: well. yes, but so is dos registered a positive result in every - printer. postmaster. scientist and 3. Gruman. op ch. p.84 software for networks, often more one of twenty consecutive runs. the statesman EW + WIV pp. 158-160). 4. Alcor UK Ltd. Unit 18. Potts expensive on a per -user costing. and force measurement ranging front

But I felt that his interest in the \larsh Industrial Estate. Eastbourne prices are falling. just under half -an -ounce right up to future was an omission. In particular Road. Westhant Sussex. I lardware to run Lnix is four ounces.

I quote from a letters he wrote to a expensive: not necessarily. a system No one has yet been able to prove friend James Duhorg. in April 1773: Keep worrying for. say four to 16 users is cheaper to how the machine works: but work it "I wish it were possible. I am writing in response to GS intplentent with a 386 -based does. [reference experiments in which he Brown's letter which appeared in machine and character terminals Talk of "dead ducks' therefore is revived flies drowned in Madeira your September 199(1 edition (Facts than with a dos network. Unix is greatly exaggerated. winch to invent a method of not pax p.817). large and unfriendly: yes. but dos is Ron Thompson embalming drowned persons, in -lis comments were offensively equally unfriendly, which is why Author "Beyond 2001" such a manner that they might he patronising and I am amazed that most users have a graphical or text - Dundee recalled to life at any period. anyone of professional competence based menuing system. Creating a Scotland however distant: for having a very could openly advocate that worrying text -based set of menus in Unix is a ardent desire to see and observe the about the effects of technology simple matter. which the supplier state of America a hundred years should be left to social workers. This should implement. so that the user Testing disharmony hence,I should prefer to an ordinary is tantamount to championing need never see the command line. A In his article on triple -tone audio death. being immersed with a few abdication of responsibility for the Unix system needs the constant amplifier testing (EIV +Wit' Feb. 91. friends in a cask of Madeira. until negative aspects of technology. attention of qualified and therefore Trial by three tones). Ivor Brown that time. then to be recalled to life Only human concert at all levels expensive personnel: indeed. appears to he unaware of the work by the solar warmth of that provides the necessary checks and familiarity with computers and an of Paul Miller in this area. as country!". balances to application of science in appreciation of the importance of published in sundry amplifier Although somewhat fanciful. our imperfect world. and a restraint hack -ups and other housekeeping reviews over the last couple of years Franklin's idea had a basis in the on all elitist technocracy. Wherever tasks is vital. which is why our (principally in h1i-Fi News and I/i-Fi science of his time. The 18th century there is any controversy about receptionist performs these functions Choice). microscopist van Leeuwenhock technology. wide ranging and perfectly well and very reliably. The Although the frequencies and observed that if he dried the healthy debate should he encouraged service contract should cope with relative amplitudes used a e microscopic animals rotifers they and how better to do this than to any other problems. different. Miller's technique is based could he revived by adding water. highlight the issue by publication of I could goon. but to suns up. any on the same premise: that complex Franklin believed that extending the facts in reputable journals of small business moving from a single intenutodulation products can reveal life -span would benefit individuals high calibre such as EW + 11'11 . dos machine would do well to look more about an amplifier than and the species - in distinct Your recent series of articles on at a Unix/Xenix system. It is cost- conventional. "static". single -tone opposition to opinion of his time. EMR and non -ionising radiation has effective to install. the service tests. The Epicurians. for example. been brought to the attention of contract can be cheaper, and \tiller. in fact, has taken the thought that only a limited number Justice Sir Harry Gibbs who is expansion is easy and cheap. principle a stage further. by using of pleasurable experiences were conducting the power line enquiry in \lane dos programs are also one constant tone and two sweep possible. In the Bible there are New South Wales. available for 386 -based Unix/Xenix tones. sweeping at different rates. accounts of people routinely living The information they contained systems. at prices comparable to The resulting spectrum is plotted its thousands of years in early periods. will undoubtedly he taken into their dos networked counterparts. a "three-dimensional" graph. and this gave rise to the popular consideration during formulation of Stephen Biggerstaff showing up quite unequivocally the belief that things were always better policy which will affect future Adverlech Communications 1 td harmonic and intennodulation in the past. generations of Australians. The London products generated in a DC-11)11kI-1z However unless any of readers of articles have also reached interested bandwidth. with remarkable clarity. EW + 1V N vs Ito are interested in medical specialists. Even so. these techniques still use alternative physics can come up with Many of your readers look forward Duck grouse signals which are at hest "semi - a mechanical time machine. to being kept informed about Your correspondent D Austin of static''. and the use of fully random. Franklin's wish remains unfulfilled. contentious issues. so keep up the Birmingham was quite us rong to or pseudo -random. tones would be except that is Ior the actions of a good work. assume in February issue EH' + WW an interesting further development. small group of scientific renegades. Peter Harding that gyroscopic inert:al thrust On the other hand, single -tone the cryonicists. NSW machines are a "dead duck" (Letters. tests are capable of showing up quite They freeze people at the point of Australia Quack technology p.150). a lot of detail provided they are death in liquid nitrogen. after He referred to the television made sensitive enough. and. carefully preparing the bodies with Unix supported documentary The Man Who Wants particularly. are conducted au cryoprotecunns. Reasoning is that it I was most interested to read your to Change The World in which he different frequencies and power Will he possible. by nanotechnology Unix feature in February 1991 issue says that such a device built by levels. or otherwise. for future science to EW + II/ti' (Nothing but Unix. Scottish engineer Sandy Kidd was I ligh harmonic distortion - say. repair the bodies of ageing damage Dos/Unix - the price of change. claimed to work. above tenth order - seems to have - the cause of death - freezing Open a vv indow on Dos and let in In my recently published book very strong effects on perceived damage. and restore them to a life of new life. pp. 1116- 114 ). "Beyond 20(11 '. tracing the history sound quality. and I have found it indefinite duration. While the articles were fairly of Kidd's invention, there is a necessary on occasion to measure

John de Rivaz comprehensive. I felt that they detailed description given of hots down below -IINIdB to find anything Truro nonetheless perpetuated a few myths this device was proved to work "wrong" with amplifiers which. on about Unix. Having used a small during tests conducted at specialist blind auditioning. show a subtle References SCO Nenix system in it small laboratories in Melbourne three sonic signature. This is perhaps not I. Gerald J Orman: I -i story of ideas business for the past couple of years. years ago. quite as far-fetched as it may sound.

340 ELECTRONICS WORLD + WIRELESS WORLD April 1991 cornptsmsntary straight

50mA

by I mV. That Si ill send 0.25mA but I would be the first to admit that Tr2 it is strange we can hear such small 2143792 hack up through Tr, (its model 50 imperfections at the end of what is t3 Tr 3 resistor is 40). This 0.25mA is BD139 .joined at E by 2mA/11FE = 0.04mA often a long and complex recording Hire./ 40 chain. from Tr, base. 0.29mA flows up In the same issue. you discuss Tr4 through the I(N152. raising E by 2153716 generator. some research on the phenomenon Him >50 29mV. So B was a 30mV of absolute pitch (Singing the blues But our real B is 2(111mV. and as or reds. or greens or...). all goes in proportion the extra bias - adjusted 0.5 v,° current through the 0.50 is not 2mA I have absolute pitch. and have 0.5 always found it most peculiar that but 2(81/30 x 2 = 13mA. others do not. There seems to he Straight Darlington produced more to it than memory of what a 300mA, so complementary does 23 better. Game. set and match to note sounds like. for I can also sing times or whistle a note on pitch (or at least the 0.552 resistor, to produce the Thus It1mA lions down to D Linsley Hood! handles one very close) w ithout preparation. same increase in quiescent current as raising it by SmV: Vin was 6mV. This discussion only he the factors that determine thermal implying that I remember physically before. Since the generator at A may of what the note feels like. Thermal stability is the same for considered instead as part of Vin it stability. But a general conclusion So why can singers not do this? both circuits! now follows that nearly all the 2mV can already he drawn. Any other The human voice has certain In his January 1991 letter (Audio at A appears across the 0.50 system would be of real interest if it characteristics which are remarkably amplifier bias current p.53) JN Ellis resistor. to give an increase of 4mA threw out the amplified diode. the dangerous thermal pitch -constant. For example I points out a slip: 2mV generators in quiescent current. together with frequently accompany a singer who inserted at F and at G will produce The methods that follow show balancing act that it supports. has certain vocal problems. always tw ice the voltage of the single that B has little effect. But compare Such a system was proposed in + WW 19911 at the same frequency. and whose generator at A. These voltages are the prey ions paragraph: the two my October article (Eli' speaking voice is constant in its handed on to the 0.50 resistor. So circuits are hack once more on level Reducing crossover distortion "tuning" (both true of most singers). 1°C rise produces 8mA increase in pegging. pp.879-882) and Mr Ellis sets out to yet she does not have absolute pitch quiescent current in the straight case In practice Vin is supplied by an criticise it. But he fails to offer any and w ill often guess a note in error but only 4mA in the complementary amplified diode (pot si ith its three criticism. by up to a major third (26rá). case. w hich is therefore the better leads connected to a transistor). This Instead he relies on Reg view that the subject On the other hand. when I arrangement. largely eliminates the gradual Williamson's long commented on one occasion that a Analysing thermal effects in Tr, thermal effects of the above of crossover distortion is since w It is that in his certain recording sounded a little is harder, because of the feedback discussion, if ít is in contact jth the closed. true flat. she replied that it sounded involved. output transistors. November 1988 letter (The correct to her - and was proved Neither writer produces figures But the system is still vulnerable subjectivist manifesto pp. 1(167) Mr right! for Tr,. thus invalidating any to rapid increases in amplifier Williamson did refer to his June Richard Black comparisons of the two circuits. output. 1969 article. and he came within a London Further. both repeatedly assume that Suppose that the fully loaded whisker of saying that it had covered a 2mV generator inserted at. say. G amplifier is suddenly made to comprehensively the matter of VI ill devote its entire 2mV to deliver a steady square wave of crossover distortion. increasing the current through the amplitude one quarter of the total By courtesy of Mr Robson of Amplifying diode 0.50 resistor: no part of the 2V is supply voltage (the worst possible Stevenage Marconi I have been able 21 year WW The output stage in a class B audio needed to increase current in the case). This might cause the power to examine this old amplifier consists of two halves. one transistors. With sub -ohmic emitter transistor junctions to heat 1181°C in article. a nd it makes just one point for each direction of current. Each resistors. this is an invalid a kw seconds. with much less effect on crossover distortion: fully stages would hall is normally a Darlington procedure. on the other transistors involved. complementary output structure. either complementary or To summarise. the Dynamic (time -related) behaviour eliminate the odd harmonics that straight. as shown in Fig. I. correspondents have assumed VIE of this kind is much more likely to cause most of the unpleasantness. In his November 1989 article remains constant as current changes. trigger runaway than the gradual Magisterial and indeed prescient. (EW + Wit' Solid-state audio power In fact the change in Vt{E may be drifting discussed above. In the but scarcely comprehensive. and pp.1042-1(148) John Linslevy flood accurately modelled by assuming straight case. 1(10°C rise produces in certainly no criticism of the October said that the complementar- that V1 does not change. but that effect a 200m generator at G. article. arrangement has better thermal there is in series with the emitter a Noting the 0.50 model resistor in In his December letter (EW + stability. model resistor of value 25/10. where series with Try emitter. just I(N)mV 111N 199(1 Crossover distortion pp.1(144) Margan of Ljubljana But Les Sage disagrees. In his I is emitter current in inA. falls on the real 0.50 resistor. The Erik March 1990 letter (Audio power For example. Try has a model bias current has increased by 21(1mA does comment on my October pp.236-237) he examines first the resistor of 0.50. in series with the - only an approximate answer article. straight case. and notes that the 0.50 shown. It is now clear that 1°C because change in I is no longer Ile observes that measuring spikes is an insufficent criterion for electrical effect of a I °C rise at rise in the straight case produces small. An accurate method predicts either junction can he modelled by 4mV total at F and G. but only 2 mV 300n1A increase). crossover distortion. The temporary ski, of higher inserting a 2mV generator at F or at of this falls across the real 0.50 The complementary circuit fares itch -off they cause G. This produces an extra 2mV resistor. to yield an increase of just much better. when a 2(X)mV frequencies is most important. But across the 0.552 resistor. thus fixing 4mA in the quiescent current. generator is dropped in at B. can this happen in the proposed the increase in the quiescent current Suppose Vin increases enough to To see what happens. work from system. where the spikes only last through that resistor. augment Trt V by ImV: co:lector a less enmeshed variable. Suppose l ls. and are not 167 times (as I Then he observes the same current will increase by 0.25mA (the that generator B has lowered C by wrote) hut 333 times less serious resistor in the complementary model resistor is 40). 4/5 of this ImV. Well. the model resistor for than those he has tested? circuit, and concludes that a 2mV cones from Tr, base (from B Tr, Tr, is 0.50. so its emitter current Michael McLoughlin generator at A will yield 2mV across model resistance is H/ -f x 0.552). will increase by 2n1A: this raises D 1 laherdashers' Aske's School

April 1991 ELECTRONICS WORLD+ WIRELESS WORLD 341 LETTERS

could manage anything more than Unsound model 1(0MHz, and Mr McLoughlin's I read with interest Michael Truth and gyroscopes circuit is less relevant to power McLoughlin's article on crossover Mosfets. This simple fact could distortion in the October issue (EW From reading his description in swung back across the machine, largely account for the apparently + WW Reducing crossover February letters (Quack regaining its start attitude. A poor crossover performance of the distortion pp.879-882). technology), it is clear to me that D smaller pulse to the left followed. amplifiers tested by Vandekooy and The article is informative and Austin did not reproduce the By examining the bench marks, Lipshitz. and Margam when thought -provoking as far as it goes. experiment demonstrated by it was clear that the machine had compared to McLoughlin's simple But it has some limitations when Raymond Baxter on the BBC translated to the left without little amplifier. applied to modern power amplifier Tontorrow's World programme. rearward reaction. In effect, the Also real life amps often use topologies. Support arms for the top were stop was a mechanical rectifier Darlingtons for the output transistors I do not think anyone would use a allowed to hang vertically and the which prevented precession to the and this will contribute to the size of circuit as simple as that presented centre of the support pin was right. the crossover spikes. except for amplifiers of I or 2W assigned to be the reference point On the fifth of May, 1972, I Mr McLoughlin recommends use capability in non -critical on the machine. A stop was showed Professor Laithwaite a of a current source in the collector applications. where it might be arranged to halt the support arms 101b machine, the bearing losses of circuit of the second stage of his argued that cross -over distortion is moving beyond the vertical to, say, which were sustained by IOW of amplifier, to reduce the effects of not a significant consideration. the right. electricity. The length of the first crossover distortion. The major problem as I see it is In operation, the top moved to pulse was about 8in, which took Most modem power amplifier that Mr McLoughlin's circuit model the left, the frame to the left and, at the device completely beyond its designs already use similar circuits is not sufficiently representative of the end of the traverse swing, the original boundaries. in that position and so Mr modern amplifiers in two main supports were again touching the I have an affidavit to that effect. McLoughlin's suggestion is a bit areas. First, nearly all modem audio stop. pointless. Many amplifiers use a power amps of average to high The top now behaved as a Alex Jones push pull arrangement which is performance use differential pairs in simple Newtonian pendulum and Channel Islands usually more linear and can provide their first stages. The differential (or more gain from the stage. long tailed) pair provides greater I feel that the major shortcoming signal handling capability. linearity capability and much higher common maximum output voltage swing of of Mr McLoughlin's article lies with and common mode rejection mode rejection. more than approximately 2V peak his failure to relate the work he has compared to a single transistor, at Another point to consider is the (4V peak -to -peak). This is very done with his amplifier to modern the expense of some gain. power supply voltage. The biasing inefficient use of the available amplifier topologies, and there are Second. Mr McLoughlin's model requirements of most input stages supply and could not he tolerated in important differences between his uses high gain small signal are such that they cannot a modem high powered amplifier. amplifier and modem class B power transistors in the output stage. which accommodate both supply voltages Another point that Mr amps. are quite different from the large and in their input (or output) range. McLoughlin has largely ignored is Based on this I find his relatively slow power transistors In fact most power amplifiers the different frequency conclusions are dubious, in normally found in power amps, and cannot accommodate either supply compensation required for a unity particular his claim "that the quite different also from power rail voltage at their inputs. To gain amplifier and its effect on slew amplified diode has had its day". Mostets. maintain a reasonable efficiency, rate. Very few amplifiers can In my experience, when crossover Use of differential pairs is supply voltages are kept as low as provide the same slew rate at unity spikes appear in an amplifier no perhaps the most important with possible while still delivering gain that they might at higher gains. amount of feedback will remove regard to Mr McLoughlin's sufficient voltage to obtain the say 30dB. them, and the only acceptable course conclusions. required output power. Inadequate slew rate is probably of action is to avoid them in the first For differential (long tailed) pairs However if the amplifier's input the dominant cause of TID. Slew place. the impedance seen from the emitter is required to handle full output rate is an important parameter that I cannot see that Mr McLoughlin of either input transistor is pretty voltage of the amplifier, as it would must he considered when designing has presented an acceptable much just the intrinsic emitter if the amp had only unity closed a power amp and, for a given design, alternative to the amplified diode, resistance (re) of the other transistor, loop gain, then larger supply lower gain usually necessitates except for simple amplifiers of about and the first stage gain has little or voltages would he required for the lower slew rate unless other design IW output power. Having said that I nothing to do with the impedance of input stage. requirements are sacrificed. It is must say that I did find the article the feedback circuit. This implies either two sets of pointless to trade one :ype of interesting and thought -provoking. I Under these circumstances supply voltages, or larger supply distortion for another when an think that reconnecting the reducing the amplifier's closed loop voltages for the whole amplifier alternative design reduces both. compensation capacitor (to the gain to unity would not provide as which means a less efficient As for the output transistors, Mr output terminal) looks like a very much benefit as Mr McLoughlin amplifier and output transistors with McLoughlin has not allowed for the sensible idea. Perhaps further would have us think. The higher power ratings and bigger much slower response of power investigation of the subject might he subsequent increase in feedback heatsinks - all adding considerably transistors compared to the small in order with a circuit more should reduce all distortions, as we to cost of the final unit. signal transistors he has used in his representative of modem Class B expect feedback to do, but reducing It is revealing that all of Mr model. amplifiers. the amp's gain to unity might have McLoughlin's measurements appear When configured as an emitter Phil Denniss some rather undesirable effects. to have been done at an output level follower a bipolar transistor has a University of Sydney Australia For example a 50W amp would of 2V peak -to -peak with a total 3dB bandwidth approximately equal he expected to deliver just over 28V supply voltage of 9V, and very little to its fT. For a BC 109 this might he to an 8i2 load. If it were a non - attention has been paid to the full between 100MHz and 300MHz. and inverting amplifier with a gain of power capabilities of his circuit. for a BC 327 it might be 50MHz to unity then the input voltage would In fact it the DC voltage at point I50MHz. have to he 28V as well, requiring an F is only 2.7V (as stated in his Fig) It is unlikely that any Editorial survey: use the information input circuit of large signal handling then we could not expect a bipolar power transistor card to evaluate this article. Item Q

342 ELECTRONICS WORLD+ WIRELESS WORLD April 1991 LINIPLEX Loop Antenna

50kHz - 30MHz

* Only 1 metre wide * Classic loop characteristics * Figure of eight directivity * Deep broadside nulls * Effective at ground level * Sensitive only to magnetic field * Rejects power line interference * Weatherproof and lightweight * Current driven push-pull amplifier * Patent pending

PHASE TRACK LTD., 16 Britten Road, Reading, RG2 OAU. England Tel:O)3a0734 75266675266 PHASE) TRACK CIRCLE NO. 148 ON REPLY CARD

... the name for atmos good value (trading since 1976)

FULLY IBM COMPATIBLE 286 AND 386 AT COMPUTERS

High performance 286 basic system at £349 High performance 386 basic system at £779

286: * 12 MHz. (Landmark speed 16MHz.) 80286 processor complete with 1 Mbyte of RAM, expandable to 4 Mbytes * 1.2 or 1.4 Mbyte floppy drive * stylish 101 keyboard * IDE hard drive controller (MFM and RLL options) * 8 expansion slots * monographics card * co -processor socket * AMI BIOS with full set-up routine and diagnostics including hard drive format * comprehensive user and technical manuals; £349 plus VAT. .rtrrn;rnr^I, 386: * 25 MHz. (Landmark speed 33 MHz.) 80386 processor complete with 1 Mbyte of RAM expandable to 8 Mbytes * otherwise the same configuration as above. Note: a full 386 system with 32 bit cpu. * Desktop version; £799 * Tower case version; £879. We will configure systems to your specification. For available monitors, hard drives, cards and add-ons see page 360 of this edition. .. / a Access and VISA orders accepted .`í ' MATMOS LTD. UNIT 11 THE ENTERPRISE PARK, LEWES ROAD, LINDFIELD, WEST SUSSEX RH16 2LX. Tel: (0444) 482091 and 483830. Fax: (0444) 484258. SEE OUR OTHER ADVERTISEMENT ON PAGE 360

CIRCLE NO. 149 ON REPLY CARD

April 1991 ELECTRONICS WORLD+WIRELESS WORLD 343 EPROM Programmer The LePROM Cards EPROM Emulators

* PC plug-in * l'C plug-in * Programs EPROMs from * Menu driven system 2716 to 27101 * Cuts development time

* Adapters available for * 1 pod emulates 2 El'ROMS at once single chip micros * Total 4 pod capability

* 1 gang (EW70I) £185 * Emulates all 24 and 28 pin types * 4 gang (E\1704) £225 * Supports 8 and 16 bit bus widths * 8 gang and production also * Expandable to 32 bit bus widths available * Also available LeMEG for 1\1b * 8751 adaptor £75.00 EPRO\Is and LeIIIG fort Mb * 2/4/8 Mb programmers available EPROMs. * (1IE1' 801, HEI' 804, HEI' 8118) * from £495 MPE PowerLogic Development System CATALOGUE of more hardware and cross -support software Half length I'C plug-in available on request. Programs : Lattice/National, SGS GALs I6V8A, 20V8A Altera/Intel EP310, 320, 600. 610 MicroProcessor Cypress/TI C22 V 10, ('20G 10 Engineering Limited ICT PEEI. 18CV8, 22CV10, 22CV 10'/. 133 Hill Lane Integrated logic equation assembler for each device Southampton Easy to install SO1 5AF \lenu driven system from £345 TEL: 0703 631441

CIRCLE NO. 150 ON REPLY CARD

C -Compilers The American Option ys Developed with 12 years experience, true System Request processor specific ANSI and KerR C - Compilers, are now available complete with AT Compatible Personal Computers free Assembler and Linker. 1802, 1805, 6301. 64180, 6502, 6800, Desktop design with 80286/12 Mhz CPU, 6801, 6802, 6805, 6809, 6811, 68000, 1MB RAM, 1.2MB Floppy Disk Drive, 8051, 8085, 8086, 8Q96 and Z80. Dual Display Card, Serial and Parallel ONLY £595 Ports, Keyboard and 14" Paper White and now 86C010 only £895. Monitor. Development System support for over 150 devices is also available, complete with Prices from £479 + VAT High Level Debugging, to see you through your complete software and hardware design cycle. A full range of upgrade options is also available. Call us now for your FREE active The above price excludes delivery. All machines are demonstration disk. subject to availability and are supplied with a 12 month Return to Vendor Warranty. E&OE. american automation System Request uk oxford PO BOX 40, ROMSEY, UK Oxford Tel: (0993) 778991 Fax: (0993) 702284 HAMPSHIRE, SO51 8WR. Lea View House, Two Rivers Estate, Station Lane, Witney, Oxon OX8 613,1 Telephone 0860 641855

CIRCLE NO. 151 ON REPLY CARD CIRCLE NO. 152 ON REPLY CARD

344 ELECTRONICS \WORLD+WIRELESS WORLD April 1991 AUDIO

FM RADIO: PLAYING A BETTER TUNE

n the first part of this article I looked cuit. which is a function both of the extent at the reasons for the growth of VI IF and the direction of mis -tuning of an input radio broadcast systems in which the signal. as a basis for some form of auto- 11 carrier was modulated in frequency. matic frequency control. Miller capaci- rather than in amplitude, and at the evolu- John Linsley Hood tance circuits of the kind shown in Fig. 1 tion of receiver designs for FM transmis- continues his short had been known and used for many years sions. in other applications and would have Although workable and offered as nor- series on FM receiver allowed a useful degree of frequency con- mal commercial products, these early FM trol in the oscillator circuit of an FM radios were not entirely without residual design, looking at the superhet radio. It is now, of course. an problems. Most annoying were the very way in which easy matter to arrange this type of control high levels of inter -station noise and the by the use of a Varicap diode connected in short-term thermal drift of the tuning set- component parallel with the oscillator tuned circuit. ting. due to the heat generated by the The use of AFC is not, in itself, a com- receiver valves. development has plete answer to the problem of tuning

I felt that a suitable point to end this drift, unless this is fairly small anyway. In part of the article was in 1960. when the influenced technique the presence of uncorrected drift, the first transistor -operated designs began to receiver AFC circuitry may pull it into appear, since these, being cool running, tune on an adjacent signal channel at offered at least the possibility of avoiding switch -on, rather than the one to which it the second of these problems. had been tuned when switched off.

Stability of tuning Inter -station noise From the inception of FM broadcasting on Even after the widespread adoption of the VHF bands. it was obvious, particular- cool -running, solid-state circuitry had ly to those hostile to the adoption of the made short-term tuning drift a relatively system in the first place, that there would minor problem. there remained the prob- he a practical problem in obtaining ade- lem of off -station noise. This was particu- quate stability of tuning. This would arise larly conspicuous in high -gain systems because a 0.1% drift in the resonant fre- using amplitude -limiter circuitry, since

quency of a I MHz tuned circuit, which the thermal noise of the input stage would would be relatively unimportant in the 8- he amplified to become a wide -band FM 10kllz pass -band of a typical medium - signal at an effective 100% modulation wave AM receiver, would he unaccept- level. able in an FM discriminator system From the point of view of the amateur intended to operate on a ±75kHz carrier constructor a simple. if rather expensive, deviation. answer to the problems of both inter -sta- Because of this need to operate at rela- tion noise and drift was to use a crystal - E tively high frequencies, most of the valve - controlled oscillator, its operating fre- operated FM tuner designs of the time quencies being appropriate to the three suffered from some drift in tuning fre- BBC channels broadcast ill any given quency, though efforts were made to min- 1 area. so that the radio could he switched imise this irritating problem by the sensi- from one channel to another without pass- ble choice of components. circuit structure ing through the noisy inter -station region. and layout. This was a widely adopted approach in In retrospect, it is surprising that so few FM receiver systems using pulse -counting circuits of the time used the mean direct - demodulators".3. for which stability of voltage output of the FM demodulator cir- the IF output frequency was essential.

April 1991 ELECTRONICS WORLD+WIRELESS WORLD 345 AUDIO

that of the surface acoustic wave or ladder filters used as replacements for band-pass Electrical tuned circuits. output Electrical Ceramic ladder filters. Front the manu- input facturing point of view; a significant dis- advantage of an FM tuner, in comparison with a more conventional AM one. was that any FM receiver design will use a rel- atively large number of tuned circuits in the RF. mixer, oscillator, IF and demodu- lator stages. Fig.3. Basic construction of surface All of these would need to he correctly acoustic wave filter. Fig.!. Vari-mu pentode used as Miller - adjusted during the manufacture of a com- capacitance stage for AFC purposes. mercial receiver, which would be a niobate. These have acoustic velocities in labour-intensive. time-consuming task. the range 2000-5000m/s and the spacing However, quite apart from considerations The availability of pre -tuned piezoelectric between the adjacent metallic digits will of cost, the use of crystal -controlled oscil- hand -pass filter circuits therefore filled an usually be of the order of half a wave- lators lacked appeal to the commercial urgent need. especially since the pass - length, depending on the design type, the manufacturer making products for use hand characteristics would be repro- pattern of metallisation depending on the country -wide, although in 1961 STC ducible and could well be superior to transmission characteristics required. The offered a range of three -crystal packages those available from a conventional pair method of construction of some types of mounted in a 139G -type glass envelope to of band-pass. coupled tuned circuits. these devices have been shown by Murray allow a change of frequencies. Their method of operation, shown in and White56. Various techniques were employed for Fig. 3, is based on the fact that an inter- Filters of this general type have been inter -station noise muting in continuously laced (interdigital) pattern of transverse available at least since the middle 1960s tuned receivers, hut the most common conductive stripes on the surface of a thin and are currently offered, for a variety of method was to derive a voltage propor- wafer of piezoelectric material can he applications, by a number of manufactur- tional to signal strength, which could then made to launch a surface ripple (the sur- ers, such as Brush-Clevite, Murata, he used to operate an audio switching cir- face acoustic wave) in response to a spe- Philips, Toko, and Vernitron. Figure 4 cuit. as in Fig. 2. An ingenious alterna- cific input RF signal. This ripple passes shows typical pass -band characteristics tive system, based on the detection of high down the wafer and induces a voltage in for a ceramic ladder filter intended for use frequency components in the demodulated another interdigitated group of metallised in a I0.7MHz FM IF strip. The actual output and used to operate a fet switch, stripes tun her along the water. performance will he influenced by the was shown by Hinch4. 13v adjusting the number of metallic source and load impedances employed, In its most convenient and economical stripes, the spacing between them and the which may typically be in the range 200- form, such a facility could he included extent to which they interleave, the RF 330Q. within the circuitry of the limiting ampli- pass -hand of such an electromechanical fier/demodulator IC as. for example, in filter can he very precisely controlled. It is RF transistors. At the time of the 1960 the RCA CA3089E of 1974. customary to terminate the ends of the circuit design by Harvey, to which I ceramic wafer with some mechanically referred at the end of the first pan of this absorbent material to avoid unwanted end article, the HF transition frequency of the The growth of solid -slate reflections and the reverse face of the best available transistors was inadequate technology water may be similarly treated. although it for RF amplification purposes in the Techniques evolved in the I960s for the is said that 95% of the energy remains IOOMHz band. The author therefore manufacture of IC chips, in particular within one acoustic wavelength of the sur- adopted a circuit which avoided the need those for the deposition of precision pat- face. for an RF stage, though this limited the terns of metallisation on a substrate, lent Various materials are employed for receiver sensitivity and could have themselves also to other purposes, of such ladder filters, such as barium increased the leakage of unwanted radia- which one of the more unexpected was titanate, aluminium nitride and lithium tion at the local- oscillator frequency.

.10V

k3

2y2 GI 0A95 10k 2N4

IF 1P7Mttz 100k r OÁ95 39k 47 1n1 182 741 1k AF of

8k2 '"'220u n ,.100k 97 107 107 112 FREQUENCY (MHz) AF input

Fig.2. Autocratic noise muting circuit operated by IF output Fig.4. Transmission characteristic of FM IF ceramic filter. signal strength.

346 ELECTRONICS WORLD+WIRELESS WORLD April 1991 AUDIO

Even when transistors with better F, values became available. problems of instability due to internal feedback were still difficult to avoid, without complex neutralisation circuits. The use of a grounded base RF transistor stage of the kind shown in Fig. 5 avoided the problem and this method was widely used for many years in inexpensive tuner -head sys- tems, although the high degree of damp- ing of the input circuit reduced image - channel rejection. What was needed. clearly. was a tran- sistor equivalent of the screened -grid valve. in which there was effective capac- Fig.s. Low-cost tuner -head design of /967, using self-oscillating mixer. itive isolation between the input and out- put electrodes. The early experimental a germanium dual -gate Alcatron, junction All netaltising fet described by Martin7) ill 1961. clearly S offered the possibility of internal electro- screening. it was static although construct- Sio2 ed using rather primitive alloy diffusion P- substrate technology. (a) Although. many years before. Shockley and others had envisaged a transistor in which current flow through a depleted Fig.6. Structure and circuit symbol of du ai-gate depletion -type mosfet. semiconducting channel could he aug- mented by an externally induced electro- are slightly worse than in junction lets static charge, attempts to make such when used in similar type circuitry. the +1 5V devices work had been frustrated by the enormous convenience of these devices in 1N 4148 difficulty in achieving the necessary RF amplifier and mixer stages has made degree of purity at the insulator -channel them exceedingly popular with designers. gate junction. An elegant FM tuner using them was

were solved described by Nelson-JonestO.t I in 1971. These practical problems 220p in the early 1960s and single insulated - This circuit also employed ceramic ladder gate mosfet transistors became available filters in the IF stages and is, in many 8k2 220p Tuning in 1963-4. Amplifier and oscillator ways. typical of modern FM tuner design voltage AFC Up designs using these were described by practice. Butlers in 1965 and an RF/mixer stage for L P1186 Tuner was Nelson - an FM tuner using mosfets described Tuner head units. Although head by Rohde9 in 1966. Jones took the somewhat bold step of While these single -gate mosfets had designing his own RF and mixer stages. it excellent RF characteristics. they had a was by this time. becoming increasingly significant internal gate/drain capacitance, common for both manufacturers and ama- 200k which meant that RF amplifier stages teur constructors to rely on specialist sup- 2k7 4N7 using these devices needed some form of pliers for complete pre -aligned tuner - neutralisation to avoid instability. unless head modules, based on grounded-hase the stage gain was kept low. Source/gate junction transistors. neutralised junction capacitive isolation was provided by the fets or mosfet RF stages. with either junc- Fig.7. Skinglev and Thompson Varicap- dual -gate mosfet. introduced by RCA and tion fet or ntostet mixers. diode thermal compensation. others a year or two later. These head units used either ganged air - Figures 6a and 6b show the circuit spaced tuning capacitors or more often pensate for the temperature dependence of symbol and constructional form of the Varicap diodes. because these would the Varicap diode capacitance. This cir- dual -gate mosfet. Modern devices of this simultaneously tune a greater number of cuit also used an ingenious AF output - type offer signal -gate mutual conductance tuned circuits, in the interests of better muting circuit operated by amplitude - values in the range 2-1211iS and gate I to image channel rejection and s:n ratio, and modulated components in the IF output. drain capacitances as low as 0.01 pF, cou- would also facilitate the use of automatic pled with a relatively high output frequency control. However, the reverse impedance of more than 50kS2. voltage/capacitance characteristics of IC IF and demodulator stages It is customary to incorporate a pair of these tuning diodes needed careful match- The process of simplification by the use back-to-back zener diodes on the chip to ing. of pre -aligned tuner -head modules and protect each gate from possible electro- A very popular tuner head module at ceramic -filter IF tuning blocks continued static breakdown. as indicated in Fig. 6c. the time was the Mullard LPII}{6 with the development of ICs for IF ampli- though these are usually omitted in the Varicap-tuned unit. An FM tuner design fication and demodulation. Figure 8 circuit symbol. based on this head unit, described by shows the Motorola MFC40IOA IF ampli- Although the noise figure and resis- Skingley and Thompson' 2, used the ther- fier block of 19621 and the MCI35I P lim- tance to cross-ntotlulation of these devices mal correction circuit of Fig. 7 to cont- iting amplifier/demodulator of 1969 is

April 1991 ELECTRONICS WORLD+WIRELESS WORLD 347 AUDIO

transistor chain Tr11_17. A second RF sig- of a single tuned circuit, which could be nal, derived from the single tuned circuit replaced by a suitable fixed -frequency L1C1. is fed to the second port. Trl tl. via ceramic resonator. the butter emitter follower Trio. In the circuit of Fig. 9. transistors Tr1.q If there is no signal to Trio, or if this Corm a high -gain RF amplifier block. in signal is in phase quadrature with the which amplitude clipping is achieved by incoming RF signal (the condition that limiting the possible collector voltage exists if L1C1 is loosely coupled to the RF swing to about I.}{V p -p. This method of input signal and is tuned to the same fre- amplitude limitation, by driving the tran- quency) the current flow through the tran- sistors into saturation, is less good than sistor chain is equally divided between the hack -to -hack diode technique adopted Ir11.13 and Trl,.t-t. and there is no change in the RCA CA3089E and the later in the current flow through R,11. CA31 t{9E. Fig.8. Motorola MFC-10111 IC Kt' gain If, however, the phase of the RF output block. from L1C1 is caused to shift away from quadrature by a change in the input fre- 3089 and the 3189 shown in Fig. 9. quency, there will be a change in the A major requirement for an FM IF ampli- By this time, demodulator systems such mean current through R,11 and a conse- fier/demodulator system is that there as the Foster -Seeley and ratio -detector quent RF-frequency-dependent output sig- should he enough IF gain to cause limit- had been superceded by this type of sin- nal. ing at an aerial input voltage of less than gle -coil gate -coincidence detector circuit. This can provide a low distortion (0.3- 5111V. to allow adequate performance in RF signals are amplified by the transistor 1.59( ) demodulation system for an FM fringe areas. In practice, this probably chain Tr" and fed to one port,Tr15, of the signal. which only requires the adjustment implies an IF input sensitivity, at the lint -

Fig.9. MC1351 FM IF strip and demodulator.

750 IF output 480

Fig.10. Limiting IF amplifier gain block used in RCA CA3089E.

348 ELECTRON ICS WORLD+W I RELESS WORLD Apri l 199 I AUDIO

iting threshold, in the range 10-50mV. voltage is derived from a secondary out- References It is also desirable that the demodulator put from the gate coincidence detector. I. Wireless World pulse counting FM circuit should have a distortion level of Although this IC is still widely used. an receiver. 1%'ireless World July, 1964, pp. 0.5% or lower. that it should he simple to improved version. the CA3I89E. was 326-333. adjust, that the recovered audio output introduced by RCA in 1977. It gives a 2. Hopkins, J. C. Wireless World, voltage should he 0.5V RMS or more to 5á13 improvement in stereo signal-to- September, /965. pp. 420-422. operate stereo decoder circuitry without noise ratio and an improved inter -station 3. Frost, E. D. Wireless World, December, further amplification and that facilities noise muting circuit, in which a DC signal 1965. pp. 586-590. should be provided for AGC, AFC. inter - related to the IF frequency deviation was 4. Hirsch, P. Wireless World. November, station noise muting and some method of added to the signal -strength control volt- 1973, pp. 547-548. tuning indication. age to improve muting operation at fre- 5. Murray. R. J., and White, P. D. All these needs were met, for the first quencies close to a high-level channel. Wireless World, March, 1981, pp. 38-41. time in a single IC, with the introduction This later IC has been exceedingly suc- 6. /deny. Wireless World. April, 1981, pp. in 1971 of the RCA CA3089E, which uses cessful commercially. Because of its 79-82. the very highly developed IF amplifier excellent performance. it has imposed a 7. Martin. A. J. V. Wireless World, May, circuit shown in Fig. 10. A cascode-con- degree of design conformity in the choice 1961. pp. 238-241. nected input long-tailed pair Tr1_5 feeds of amplifier and demodulator method 8. Butler, F. Wireless World. February, two further stages of symmetrical push- used in contemporary designs, although it 1965, pp. 58-61. pull amplification Tr7-20, which drives the is still practicable to use this IC in non- 9. Rohde, U. L. Wireless World, January, gate -coincidence detector via the hack -to - standard F \1 circuitry. such as a recent 1966, pp. 2-6. hack diode limiter mentioned above. phase -locked loop design of my ow1113.14 10. Nelson -Jones, L. Wireless World, Each of the RF amplifier stages is also In the final part of this article, I will April, 1971, pp. 78-92. arranged to feed a current summation cir- look at the techniques used tot the broad- II. Hem. Wireless World. April, 1972, cuit to allow both a tuning meter and an casting and reception of stereo signals. pp. 179-183. inter -station noise mute circuit to he oper- together with some of the recent innova- 12. Skingley. J. A.. and Thompson. N. C. ated from an output voltage largely pro- tions in commercial receiver design. Wireless World. April, 1974, pp. 48-60. portional to the size of the input IF signal. 13. Linsley Hood, J. L. Electronics Today, This circuit also provides a control volt- V arch. 1987, pp. 34-38. age for an AGC system w hich can be Editorial survey: use the information 14. /dent. Electronics Today, April, 1987, used, where appropriate. with the RF and card to evaluate this article. Item N pp. 33-37. mixer stages of the tuner head. An AFC

HALCYON * PRICE * PERFORMANCE * PROFESSIONALISM * = 3P SYSTEM] ELECTRONICS Computers, test equipment, video monitors, amateur radio gear, oscilloscopes, scientific instruments, connectors, printers, power supplies, communications, disk drives, multimeters, component bridges, frequency counters, signal generators, semi -conductors, SPECIALintegrated circuits,OFFERS etc. FARNELL E350 VARIABLE STABILISED PSU'S 0-350V 100MA V A METERS, 6.3V 2A CT, 0-2.5-5-6.3V 3A C49 NEW BATCH LINSTEAD M28 MILLIVOLT METERS, BATT OP RANGES 1.2MV-400V AC, 120MV-400V DC. £19 NICAD BUTTON CELLS 100MAH 6V FLAT PACK STACKS, EX NEW EOUIPT. £2/STACK.10 FOR C16 . ''a ..u.urc aa.i..1.2~..0 ti nn;":17,1 -,11-_ MICROVITEC HL FST MONS RGB ANAL COMPO. SND f 149 LYONS WG716 16M Z WORD GENERATOR £245 .1111 pi -4i RE /POINT 6E-1 HEATSINKS 1.5"CW BRAND NEW C1.50 MICROWA ANALYTICAL BALANCE C69 BBC -B COMPUTERS C139 6 1179 (DOS) H.P. 5004A SIGNATURE ANALYSER 95 Systems built to suit your requirements NELSON ROSS SPECTRUM ANALYSER 0-20KHZ £295 EPSON PO4 8 TF15D TWIN FLOPPY f175 CT491 CABLE TEST SET, 700YDS, CRT DISPLAY £59 WAVETEK 2001 SWEEP/SIG GEN. TO 14GHZ f1995 286/12 286/16 3716/SX 386/25 386/25C 386/33C 486/25

DATA PRECISION 6000 W/F ANAL - 681 ()'DRIVE £1495 1N4004 6000 OFF (THOMSON-CSF) £125 BASIC SI"STEM £395 £430 £565 £795 £8811 £1095 £2150 TRACKING ANALYSER HP97 SCIENTIFIC CALCULATOR, LIKE NEW 95 TEXSCAN 9650 SWEEP 1695 RAM 1MB 1MB 2MB 4MB 4MB 4MB KMB RACAL DANA 9341 DIGITAL LCR BRIDGE £295 NESTAR 4722 6PORT HUBS £29 AVO CZ 457/5 COMPONENT COMPARATOR C75 BAT LAB OVENS 12x13x14 INTERNAL 210`C C195 HARI) DISK 411MB 411MB 411MB 9115113 90MB I35MB 15115113 MARCONI TF2300 FM AM MODULATION METER E195 MARCH DPL300S ELECTRONIC LOAD 60A 400 C175 14" MONO TTI. £698 £733 £918 £1383 £1468 £1739 £3148 TEKTRONIX 5458 OSCILLOSCOPES Fan £65 PASCALL BALL MILL. VARIABLE SPEED 95 WANDEL 8 GOLTERMAN TFPM-43 8 TFrS-42 EA C55 TEKTRONIX 4662 PLOTTERS, GPIB 8 RS232 £179 14" MONO VGA £728 £763 £948 £1413 £1498 £1769 £3178 OLIVETTI 32MB EXT WDRIVE HDU2432 0149 OTHER PLOTTERS From £95 14" ULTRASONIC CLEANING BATH, 5 LITRE 1195 HP COMPUTER 9825B, 15263A. 98032A OPT. 066 £195 VGA UN 200W SHUTTR OP, TIMER, 240V £89 MICROWAVE BY H.P. KELTEC, VARIAN, ETC. POA COLOUR £853 £888 £11173 £1536 £1623 £1894 £3303 HITACHI CH2073A301 20' RGB 64kHz. CAC DTP E495 B8K 1019 AUTO VIB EXCITER CONT+HEAD £85 14" SUPER VGA KUNKEL A10 MIN. MIXER 20K RPM £25 TECMAR 01C -60H TAPE STREAMER £95 JANKE 8 LID. COLOUR £952 £987 11172 £I637 £1722 £1993 £3402 TSWITCHES INMAC 1863 RS232 2 -WAY C40 GOULD K100 D LOGIC ANALYSER £595 LEAKSEEKER 46 PORTABLE GAS DETECTOR £95 LEADER LCG 396 NTSC PATT. GENERATOR £195 III% )iseount on all systems unlit end o May 1991 RACAL CSC RECEIVER 1772E1521131F/0 £1950 UDI 2026 SONAR SCANNER, SURFACE UNIT C995 BASIC SYSTEM = MOH-IERIrOARD, 1MI1 RAM, FLOPPY DRIVE 1.20R TEKTRONIX 834 PROG DATACOMMS TESTER £495 CONRAC 7211 HIRES RGB MONITOR 395 1.44, IDE HARD, FLOPPY, 2 SERIAL, PAR/GAMESCARD, 256 VGA IBM POLAROID PALETTE IMAGE RECORDER 72.10 £595 OSCILLOSCOPES DUAL TRACE From C75 GRAPHIC CARD. DESKTOP CASE + 2141W POWER SUPPLY, 102 -KEY AVO 8'S Mk2 5 8 6 From £55 17 GREEN SCREEN MONITORS From £39 VARIABLE OUTPUT PSU's From 135 LEADER LBO -9C ALIGNMENT SCOPE 1249 KEYBOARD TEKTRONIX 520 PAL OR NTSC VECTORSCOPES 1475 QUBEX OA 200 DISK DRIVE TEST UNIT [1495 All systems come with L'RF,E 12 -month on -site ,maintenance METROHM 9A 250V MEGGERS £79 SIGNAL GENERATORS. AF TO 12.5GHt From £20 FOR SYSTEM & ('0511'ONEN'l PRICES W RITE, PHONE OR FAX FOR A OTHER MEGGERS/MEGGER BRIDGES From £15 GALLENKAMP MAGNETIC STIRRER £29 FREE CATALOGUE. ALL PRICES EXCLUDE 15% VAT & DELIVERY.

LIST AVAILABLE, BUT 1000'S OF UNLISTED BARGAINS FOR CALLERS QUALITY ELECTRONIC EQUIPMENT BOUGHT. ALL PRICE EXC. OF P&P AND VAT 93 KENTMERE APPROACH, PANRIX LEEDS LS14 1JW. 423, KINGSTON ROAD, LONDON SW20 8JR ELECTRONICS 0532 650214 SHOP HOURS 9-5.30 MON-SAT. TEL 081-542 6383 Fax: 0532 300488 CIRCLE NO. 157 ON REPLY CARD CIRCLE NO. 158 ON REPLY CARD

Apriil 1991 ELECTRONICS WORLD+WIRELESS WORLD 349 D.I.L. SWITCHES 10 -WAY f1 8 -WAY 80p 4,5 6 -WAY 80p COMPUTER ICS 18OVOLT 1WATT ZENERS also 12V & 75V 2041 USED D CONNECTORS price per pair 80C31 MICRO £2 PLASTIC EQUIPMENT CASE 9x6x 1.25 WITH FRONT D9 60p. D15 £1.50, D25 f2, D37 £2, D50 í3.50, covers P8749H MICRO C5 AND REAR PANELS CONTAINING PCB WITH EPROM 50p ea BBC MICRO PARTS 2764-30 AND ICS 7417 LS30 LS32 LS367 7805 REG, 9 - VIDEO ULA 201647 £10 ea, 10+ f8 WAY D PLUG, PUSH BUTTON SWITCH, DIN SOCKET WIRE WOUND RESISTORS 6845 CRT C5 f 1.90 W21 or sim 2.5W 10 of one value £1 6522 PIA C3 VN 10LM 60V 1/2A 5 Ohm TO -92 mosfet 4/£1 100 420 R100R15OR212R04R75R05R68R21OR12R15R18R OM88LS120 £4.50 MIN GLASS NEONS 10,t1 20R 22R 27R 33R 4714 56R 62R 91R 120R 180R 390R AY3-1015D UART í2.50 RELAY 5V 2 -pole changeover looks like RS 355-741 430R 470R 680R 820R 910R 1 K15 1 K2 1 K5 1K8 2K4 2K7 USED 41256-15 £2 marked STC 47WBost f1 ea 3K3 3K0 5K0 USED 4164.15 ex equipment f1 MINIATURE CO -AX FREE PLUG RS 456-071 2 f1 R05 (50 milli -ohm) 1% 3W 4 for f1 9 x 41256-15 SIMM 410 MINIATURE CO -AX FREE SKT RS 456-273 211.50 W22 or sim 6W 7 OF ONE VALUE C1 8 x 4164 SIP MODULE NEW f8 DIL REED RELAY 2 POLE n/o CONTACTS £f R47 R52 1 R01 R5 1R8 3R3 6R8 9R1 12R 20R 24R 27R HD 146818 CLOCK IC £2 PCB WITH 2N2646 UNIJUNCTION WITH 12V 4 -POLE 33R 51R 56R 62R 68R 100R 120R 180R 220R 39014 560R 2864 EPROM C3 RELAY C1 620R 910R 1 K0 1K2 1K5 1K8 2K2 2K7 3K3 3K9 4K7 8K2 27128A 250ns EPROM USED C2 NEW £2.30 400m 0.5W thick film resistors (yes four hundred megohms) 10K 15K 16K 20K 27C1001 -20Z NEW 1M EPROM f 6 4 f1 W23 or sim 9W 6 of one value £1 FLOPPY DISC CONTROLLER CHIPS 1771 £10 ea STRAIN GAUGES 40 ohm Foil type polyester backed balco R22 R47 1R0 1R1 56R 62R 100R 120R 180R 22014 300R 68000-8 PROCESSOR NEW f6 grid alloy C1.50 ea 10+ f1 390R 680R 1K0 1K5 5K1 10K HD6384-8 f5 ELECTRET MICROPHONE INSERT C0.90 W24 or sim 12W 4 OF ONE VALUE fl ALL USED EPROMS ERASED AND BLANK CHECKED Linear Hall effect IC Micro Switch no 613 SS4 sim RS 304- R50 21,10 9R1 18R 22R 27R 56R 66R 75R 62R 100R 150R CAN BE PROGRAMMED IF DESIRED 267 C2.50 100+ £1.50 180R 200R 220R 270R 400R 620R 1K0 6K8 8K2 10K 15K 2716-45 USED f2 100 f1 HALL EFFECT IC UGS3040 - magnet f1

2732-45 USED C2 100 £1 OSCILLOSCOPE PROBE SWITCHED x 1 x 10 412 PHOTO DEVICES 2764-30 USED £2 100t1.60 CHEAP PHONO PLUGS 50 f2 1000 410 HI BRIGHTNESS LEDS COX24 RED 5 £1 27C256-30 USED f2 1 pole 12 -way rotary switch 4 fl SLOTTED OPTO -SWITCH OPCOA OPB815 £1.30 27C512 USED 43.50 AUDIO ICS LM380 LM386 C1 ea 2N5777 50p 1702 EPROM EX EQPT C5 555 TIMERS £1 741 OP AMP 6 f1 TIL81 PHOTO TRANSISTOR f1 2114 EX EOPT 50p 4116 EX EOPT 70p ZN414 AM RAIGO CHIP 80p TIL38 INFRA RED LED 5 C1 6264-15 8k STATIC RAM C2 COAX PLUGS nice ones 4/C1 4N25, OP12252 OPTO ISOLATOR 50p SN76489AN C3 COAX BACK TO BACK JOINERS 3,41 PHOTO DIODE 50P 6 f2 4x4 MEMBRANE KEYBOARD í1.5O MEL12 (PHOTO DARLINGTON BASE nWc) 50p REGULATORS INDUCTOR 209H 1.5A 5 f1 LED's RED 3 or 5mm 12'£1 100 f6 LM3171 PLASTIC T0220 variable f1 1.25 PANEL FUSEHOLDERS 3'C1 LED's GREEN OR YELLOW 10 C1 100 C6 LM317 METAL £2.20 CHROMED STEEL HINGES 14.5x 1" OPEN f1 each LED's ASSORTED RD GN YW - INFRA RED 2001E5 7812 METAL 12V 1A Cl 12V 1.2W small wire ended lamps fit Audi VW Saab Volvo FLASHING RED OR GREEN LED 5mm 50p 100£40 780512 15 24V plastic 25p 100+ 20p 1000+ 15p 10t1 7905 12 15 24 plastic 25p 100+ 20p 1000+ 15p STEREO CASSETTE HEAD £2 STC NTC BEAD THERMISTORS CA3085 1099 variable reg 2 C1 MONO CASS. HEAD f1 ERASE HEAD 50p G22 220R. G13 1K, G23 2K. G24 20K, G54 50K. G25 LM338 5A VARIABLE f8 THERMAL CUT OUTS 50 77 85 120°C fl ea 200K, RES 20 C DIRECTLY HEATED TYPE C1 ea THERMAL FUSES 220°C;121 C 240V 15A 5/f 1 FS22BW NTC BEAD INSIDE END OF 1" GLASS PROBE CRYSTAL OSCILLATOR TRANSISTOR MOUNTING PADS TO-5/TO-18 ... £3 1000 RES 20°C 200R £1 ea 1.8342 16.00 MHz £1.50 each TO -3 TRANSISTOR COVERS 10,11 Ala DIRECTLY HEATED BEAD THERMISTOR 1k res. STICK-ON CABINET FEET 30 f1 ideal for audio Wien C2 ea CRYSTALS PCB PINS FIT 0.1" VERO 20011 2.77MHz, 4.00MHz, 4.9152MHz, 20MHz. 49.504MHz. 8M. TO -220 micas + bushes 10'50p 100'f2 CERMET MULTI TURN PRESETS 3/4" 16.588M TO -3 micas - bushes 15 f1 l OR 20R 100R 200R 250R 500R 2K 2K2 2K5 5K 10K 47K PTFE min screened cable 10m f1 50K 100K 200K 500K 2M 50p ea TRANSISTORS Large heat shrink sleeving pack t2 BC1O7 BCY70 PREFORMED LEADS CERAMIC FILTERS 6M 9M/10.7M 60p 100 £20 IC SOCKETS full spec f1 í4100í30H000 IEC chassis plug filter 10A C3 6 pin 15 £ 1 8 pin 12 f1 14116 pin 10 £ 1 18,20 pin 7/E1 BC557, BC546B. BC238C, BC308B £1/30 í3.50 100 Potentiometers short spindles values 2k5 10k 25k 1m 2m5 2224 28 pin 4 £1 40 30p lin 4'G1 POWER TRANSISTORS 500k lin 500k log 4 t1 SOLID STATE RELAYS P POWER FET IRF9531 8A 60V 3 f1 40kHz ULTRASONIC TRANSDUCERS EX-EQPT NO 40A 250V AC SOLID STATE RELAYS 410 N POWER FET IRF531 8A 60V 2 f1 DATA £1/pr 25C1520 sim BF259 3 1:1 100 422 POLYESTER/POLYCARB CAPS TIP 141 2 C1 ea TIP 112'125,420 2 f1 DIODES AND RECTIFIERS 100n, 220n 63V 5mm 2041 10013 TIP35B TIP35C £1.50 1N4148 100 f1 .50 1n,3n3 5n6 8n2 10n 1% 63V 10mm 100 C5 SE9301 100V 1 DA DARL SIM TIP121 211 1N4004 SD4 1A 300V 100 1:3 10n115n 22n,33n 47n 66n 10mm rad 1001:3.50 2N3055 EX EQPT TESTED 4 C1 1N5401 3A 100V 10 C1 100n 250V radial 10mm 100 C3 PLASTIC 3055 OR 2955 equiv 50p 100 C35 BA158 1A 400V fast recovery 100'£3 100n 600V Sprague axial 10t1 100 f6 (C1) 2N3773 NPN 25A 160V £1.80 10 416 BA159 1A 1000V fast recovery 100 C4 292 160V rad 22mm, 292 100V rad 15mm 100 £10 BY127 1200V 1.2A 10,£1 10n/33n 47n 250V AC x rated 15mm 10 f1 QUARTZ HALOGEN LAMPS BY254800V 3A 841 470n 250V AC x rated rad 4 f1 A1/21624V 150 WATTS 42.25 BY255 1300V 3A 6 f1 1U 600V MIXED DIELECTRIC 50p ea H1 2V 50W (CAR SPOT) í1.5O 6A 100V SIMILAR MR751 4,f1 190 100V rad 15mm, 190 22mm rad 10046 14 -WAY AMP ZIF SOCKET 2 C1 1A 600V BRIDGE RECTIFIER 4 £1 TEXTOOL single in line 32-way. Can be ganged (coupling 4A 100V BRIDGE 3 f1 RF BITS supplied) for use with any dual in line devices 2 í1.5O 6A 100V BRIDGE 2 f1 TRW 50watt 50ohm DUMMY LOADS £50 28 -WAY TEXTOOL ZIF SOCKET EX NEW EQUIPMENT 8A 200V BRIDGE 2,f1.35 TRIMMER CAPS ALL 4 50p í2.5O 10A 200V BRIDGE C1.50 SMALL 5pF 2 pin mounting 5mm centres 40 -WAY TEXTOOL ZIF SOCKET C5 25A 200V BRIDGE f2 10418 SMALL MULLARD 2 to 22pF 4 50p 25A 400V BRIDGE 42.50 10422 SMALL MULLARD 5 to SOpF 4/50p CAPACITORS COMPUTER GRADE Larger type grey 2 to 25pF black 15 to 20pF 22009F 160V SIC SAFCO FELSIC C038 C4 (41.20) SCRS TRANSISTORS 2N4427 60p 24,0009F 50V C3 (£1.30) PULSE TRANSFORMERS 1:1-1 41.25 FEED THRU CERAMIC CAPS 100pF 10 f1 10,0009F 100V SPRAGUE 36D C10 (f1) 2P4M EQUIV C106D 3 f1 TOROID 350VA 35V -35V AND 15V -15V 24VA 412 TICV105D 800mA 400C SCR 3 f1 100115 MINIATURE RELAYS Suitable for RF

MEU21 PROG. UNIJUNCTION 3 f1 5 volt coil 1 pole changeover C1 MISCELLANEOUS 5 volt coil 2 pole changeover fl TRIACS DIACS 4 £1 LEMAG EARTH LEAKAGE TRIP 35A 35mA TRIP C9 12 volt coil 1 pole changeover f 1 FANS 240V 120MM f6 (41.50) BT137-800 8A TO -220 2 f 1 (OTHER VOLTAGES SIZES USUALLY AVAILABLE) NEC TRIAC ACO8F 8A 600V-1-0220 5t2 100,130 MONOLITHIC CERAMIC AMERICAN 2 3 PIN CHASSIS SOCKET 2M1 TXAL225 8A 500V 5mA GATE 2 C1 100135 CAPACITORS HUMIDITY SWITCH ADJUSTABLE f2 TRAL2230D 30A 400V ISOLATED STUD C4 each 10n 50V 2.5mm 100/£4.50 WIRE ENDED FUSES 0.25A 30,41 BTA 08-400 ISO TAB 400V 5mA GATE 90p 100n 50V 2.5mm or 5mm 100£6 NEW ULTRASONIC TRANSDUCERS 32kHz C2'pr 100n ax short leads 100,43 12 -CORE CABLE 7/0.2mm OVERALL SCREEN CONNECTORS 100n ax long leads 100,45 70p'metre D25 IDC SOCKET FUJITSU C2 100n 50V dil package 0.3" rad 100 £8 POWERFUL SMALL CYLINDRICAL MAGNETS 3 f1 34 -way card edge IDCCONNECTOR (disk drive type) OP AMP LM1OCLN £2.90 41.25 STEPPER MOTORS BNC 500HM SCREENED CHASSIS SOCKET 2 £1 CENTRONICS 36 WAY IDC PLUG 42.50 2 CENTRE -TAPPED 9 VOLT WINDINGS 7.5° STEPS £4 MAINS ADAPTOR 9V DC 200mA £1.25 CENTRONICS 36 WAY IDC SKT £4.00 SMALL MICROWAVE DIODES AE1 OC1026A 2,£1 BBC TO CENTRONICS PRINTER LEAD 1.5M £3 BULK ITEMS CENTRONICS 36 WAY PLUG TYPE SOLDER C 7912 REG 10,000 12p 1000+ USED CENTRONICS 36W PLUG-SKT f3 CNY17.1 Opto 4,000 @ 12p 1000+ PMI PKDO1-FY 150 C £3.50

MAIL ORDER ONLY KEYTRONICS MIN. CASH ORDER £3.00. OFFICIAL ORDERS WELCOME UNIVERSITIES COLLEGES/SCHOOLS,GOVT. DEPARTMENTS TEL. 0279-505543 MIN. ACCOUNT ORDER £10.00 FAX. 0279-757656 P&P AS SHOWN IN BRACKETS (HEAVY) ITEMS 65p OTHERWISE (LIGHT) ITEMS P O BOX 634 ADD 15% VAT TO TOTAL BISHOPS STORTFORD ELECTRONIC COMPONENTS HERTFORDSHIRE CM23 2RX BOUGHT FOR CASH

CIRCLE NO. 153 ON REPL) CARD

350 ELECTRONICS \\ ORII)+\\'I RELESS \\ ORLI) April 1991 MEW PRODUCTS CLASSIFIED

short-circuit capability, latch -up free, Operational amplifier. Micropower 10km. It is suitable for PCB mounting improves ruggedness. 600V units op amp needs 1.2µA maximum and simplex or duplex connectors. ACTIVE have a fast recovery diode to improve supply current and operates from Applications include NC machines turn -on losses and reduce RFI single supplies ranging from 2 to 10V, and transmitting data between factory problems (available on 1200V units or from dual supplies of up to +5V. machines. Norbain Technology, 0734 later this year). Toshiba Electronics The output of the Maxim MAX406 can 864411. Discrete active devices (UK) Ltd, 0276 694600. source 2mA when powered from 9V. 700MHz building block. Monolithic Eight -pin devices in plastic DIPs SO Laser diodes. Optilas range has OPA660 is a voltage -controlled Automotive mosfets. The 2SK943 and CERDIP packages. Kudos source sizes of 100 x 1pm, 200 x current source and voltage buffer. mosfet for the automotive market is a Thame, 0734 351010. 1µm, 1cm x 1pm, and 0.1 x 75pm. Buffer stage has a 700MHz 60V 25A device with a typical on - LDT26000 has output powers from bandwidth, 3kV/ps slew rate and rise resistance of 46m52 in an isolated Telephone IC. TEA1085 works in 125mW to 1W at 790 to 812nm. time of 1.5ns for 5V step. Uses TO220 package. Logic level line -powered sets, with a loudspeaker LCW5100 units are monolithic arrays include signal -processing stages in compatible gate drive makes it in the base as well as handset, to et with up to 10W continuous output video systems, radar, suitable for direct interface to cmos several people listen to a power. LCW100 and 200 have communications and high-speed data and TTL logic circuits. Toshiba conversation. 40mW into a 5052 wavelengths from 800 to 870nm and acquisition. Burr -Brown International Electronics (UK) Ltd, 0276 694600. speaker in BTL or 20mW in SE output powers from 250 to 500mW. Ltd, 0923 33837. configuration. Loudspeaker amplifier Optilas, 0908 221123. Mosfet. N -channel dmosfet has a with fixed 35dB gain. Philips BJ transistor model. Bipolar junction power rating of 360mW when Components, +31 40 724173. Photo sensors. TLP820 has a 5mm transistor software model can mounted on a substrate 10 x 8 by detection gap, a 50mA direct forward simulate small and large signal 6mm. The SOT23 BSS t 23 device Microprocessors and current, and 35V current emitter performance of microwave silicon has a drain -source breakdown of controllers voltage. The 860 needs 1 mA devices as well as presenting bias - 100V with typical on -resistance of 552. VGA display controller. VGA display maximum for led forward current. dependent s -parameters for linear Maximum pulsed drain current is controller improves Windows and 1200 is for use as a general purpose

simulation at any arbitrary bias point. 0.68A. At 1 mA drain current, gate - Presentation Manager performance photo interrupter with a connector, EEsof 49 81 052 4005 source threshold voltage is 2.2V. At on 386 and 486 PCs and and the 1224 is for use in 24V 25V and 100mA, transconductance is workstations. The 77C22E chip systems and is rated to 95°C. Mosfet relays. Opto -coupled mosfet 120mS. Zetex plc, 061-627 4963. provides 16 -bit operation in all display Toshiba Electronics, 0276 694600. relays have bounce -free switching modes and interfaces to AT, eisa and and provide up to 2.5kV isolation. Linear integrated Microchannel systems. NCR Programmable logic Standard six -pin DIL package; less circuits Microelectronics Europe, 0049 89 arrays than 0.5g. It can switch up to 400V at Motor driver. A 5V voice -call motor 632202. Gate arrays. CG31 units are sea -of - currents to 1A. AC and DC versions. driver IC with sense-fet outputs, the gate devices with 130,000 to 200,000 Switching times are down to 18µs and A8932CLB mixed signal IC is for Optical devices gates. They are made in 8pm input sensitivities up to 4mW. NEC positioning read and write heads in FDDI chip set. AMD is sampling an technology and three versions: Electronics (UK) Ltd, 0908 691133. hard disk drives for laptop computers. integrated circuit chip set for fibre 129,540 basic cells and 300 signal It also integrates a full-bricge current distributed data interface (FDDI) lans. I/Os; 160,930 basic cells and 332 Microwave transistors. Semelab is amplifier onto a single chip. Allegro The Supernet 2 chip set allows signal I/Os; and 201,188 basic cells starting to make microwave MicroSystems, 0932 253355. implementation of a complete FDDI and 332 signal I/Os. 70% of the basic transistors and full production is station on an AT half -card or similar cells are typically available to the planned for later this year for the Communications IC. Frequencies of sized board. It supports 400Mbit/s user. Gate delay is 370ps. Fujitsu previous Acrian style devices and Fujitsu Super-PLL communication ICs memory bandwidth. Drives fibre or Microelectronics Ltd, 0628 76100. newly developed 2GHz mosfet range. start from less than 0.5GHz for copper. Advanced Micro Devices, Semelab Ltd, 0455 554711. cellular radio up to 2.5GHz for digital 0483 740440. ECL gate arrays. ECL gate arrays TV. Power consumption is 10mA. with an internal flip-flop frequency of IGBTs. Saturation voltage is typically They can operate from 2.7 to 5.5V Optical -fibre system. Tostink fibre up to 4GHz have a clock frequency of 2.2V and current range is 15 to 400A. supplies at -40 to +85°C. Hawke optic system from Norbain can more than 1GHz and a gate switching 600 and 1200V versions. A high Components Ltd, 0256 880800. transmit signals at distances up to time of 75 to 160ps. Internal logic of the ICs consists of basic cells that FASTCache-SX accelerator card by Micro Way gives 32 -bit performance to 16 -bit 286 PCs include a master and slave circuit. Fujitsu Microelectronics Ltd, 0628 76100.

GaAs gate arrays. Fury MB5xxx GaAs gate array units have inputs that can work with ECL, TTL and GaAs signal levels. Gate delay time is 70ps, gate power consumption 1.1mW, and input signal frequencies are up to 1GHz. Fujitsu Microelectronics Ltd, 0628 76100.

Motor drive IC. LMD18200 IC can drive up to 0.25hp DC motors; two can drive a high power stepper motor circuit. It contains four power mosfets, four fast power diodes and can drive four large capacitive load mosfets at high speed (two being highside switches). It also provides low loss current sensing, shorted load protection and thermal shutdown and warning. STC Electronic Services, 0279 626777.

Apri 11991 ELECTRONICS WORLD+ WIRELESS WORLD 351 NEW PRODUCTS CLASSIFIED

digital storage mode it can capture repetitive events up to 50MHz and PASSIVE single -shot events to 5MHz. Memory length of 2000 words on each channel. Thurlby-Thandar Ltd 0480 Passive components 412451. Resistors. A range of high precision resistors for up to 40kV or 1000Mí2 Scope and monitor. 5851V applications have resistance vectorscope and the 5861V waveform tolerances from ±10%. Epoxy coated i monitor are half -rack instruments. The to minimise flashover and breakdown vectorscope displays relative problems. Power dissipation is 0.8 to amplitude and phase of chrominance 3W at 20°C. Temperature coefficient components with an accuracy of ±2%. is 150ppm/°C from -55 to +125°C. . The monitor measures signal Menvier Hybrids Ltd, 0295 256363. amplitude, timing and frequency e. response. Thurlby-Thandar Ltd, 0480 Capacitors. ZA series have a 412451. leakage current of 0.004CV or 0.2µA. They are for measuring instruments DMM scanner. An eight channel and audio devices where low noise is scanner for BCT's PC -based digital required and operate from 6.3 to multimeter combines Vip board and 100V at capacitances from 0.47 to software to support eight intelligent 47µF, tolerance ±20% at 120Hz, multimeters linked to a PC. It 20°C. Operation is rated between functions as an intelligent DMM using 40°C and +85°C. Radial packages. PC graphics software, mouse and Nichicon (Europe) Ltd, 0276 695393. Tek FiberMaster is the only OTDR to accommodate two dual -wavelength plug-in card, and can measure optical plug -ins at the same time voltage. current, resistance, decibels Ceramic capacitors. Threaded and capacitance. Measurements can bushing units have working voltages be stored. Scanner allows selection of of 100, 200, 250 and 500V DC Digital storage oscilloscopes. 4060 a different function and range for each covering capacitances of 75 to Displays family of DSOs, two and four channel channel. Four scanners can be linked. 10,000pF. Solder mount types go Led display array. Gunstar array has versions, has 400megasamples/s £175. Blue Chip Technology, 0244 from 100 to 300V and 47 to 6000pF. 16,384 leds in an area 42.3 x 42.3mm sampling, 8-bit vertical resolution, 520222. Discoidal units are rated at 500V and in a 66 x 60 by 6.7mm package. Each 150MHz bandwidth, 16 non-volatile 33 to 1000pF. STC Mercator, 0493 diode is a pixel which can memories for waveform storage, on- Harmonics module. The harmonics 844911. independently present any alphabetic, screen signal measurement and expansion module for Vip system 3 numeric or graphic display required. analysis functions, and internal hard - gives a solution to harmonics Connectors and cabling MIL883 requirements. Two ceramic copy capabilities. Gould Electronics measurement, with the module Five way/42 way din style substrates mounted on top of each Ltd, 081-500 1000. providing simultaneous three-phase connector. Erni GmbH's special size, other are contained in a hermetically monitoring of current and voltage - DIN 41612 style connector has raised sealed metal package with a Digital multimeters. The 175A 4.5 allowing printed and displayed mounting flanges, enabling it to fit transparent lid. Contraves Circuit digit autoranging instrument has 10µV information up to the 25th harmonic. between two standard length DIN Technology, 0908 222466. DC and TRMS AC sensitivity, Vip system 3 is configured for 41612 connectors on a double resistance measurement down to harmonics analysis by inserting a Eurocard in existing mounting holes. Instrumentation 10mí2, DC and TRMS AC current plug-in expansion module into the slot Two versions: one for use with up to Cable detector. Intek TEK600 hand- resolution from 10nA, and a dB at the rear of the instrument. The 42 signal contacts rated at 4A; the held detector has automatic function with internal reference to instrument includes an oscilloscope - second will accept up to five high adjustment of sensitivity and will 60011 over a 100kHz bandwidth. 197A like waveform display. Elcomponent current 40A contacts, or a similar detect dead or live cables through is a 5.5 digit version with resolutions Ltd, 0279 503173. number of coaxial or fibre optic various materials including foil -backed of 1µV, 1mi2 and 1nA. Keithley contacts. Radiatron Components Ltd, plasterboard. 9V battery. 50 x 64 x Instruments Ltd, 0734 575666. Measuring amplifier. MGC 081 891 1221. 30mm. Detection depths are 12 to measuring amplifier combines 25mm for twin and earthed cables Digital multimeter. Full rack analogue and digital technologies. A Wire to board. NR series low profile and 6mm for telecomm/computer capability in half rack size is a feature patented A -to -D conversion technique wire -to -board connectors insulation cables. Alpha Electronics, 0942 of the SI7063. The 6.5 digit unit ensures the analogue signal is displacement products have a height 873434.Atpha Electronics 0942 includes pulse width conversion digitised without losing information by above board of 13.1 mm. Height for 873434 techniques to provide continuous gate -array technology. Functions crimp types (XH series) is 9.8mm. averaging and linearity on 20 include filtering, taring, and balancing Both have a 2.5mm pitch and use the Battery oscilloscope. Hitachi's V209 measurement functions at up to 1000 of the mean point signal. It is same base post assemblies available portable, miniature and battery - readings/s with no intervals between designed to accommodate plug-in in top or side entry forms. Contact powered oscilloscope comes with x1 measurements and no polarity units, those available being intended resistance is initially 10Mí2, rising to and x10 probes and has a screen reversal errors. PPM Instrumentation for direct -voltage signals and 20Mí2 after environmental cycling. XH area of 8 by 10 divisions. Vertical Ltd, 0483 301333. thermocouples, strain gauge 3A, can be supplied with up to 20 deflection factor ranges in ten transducers and inductive poles; NR, 2A, up to 13 poles. 250V calibrated steps from 1mV to 5V per OTDR. Two dual -wavelength optical transducers. Hottinger Baldwin AC/DC with an insulation resistance division. Horizontal sweep times are plug-in modules can be Messtechnik, 0869 321321. of at least 1000Mí2. Takbro Ltd, 0444 0.5µs to 0.2s in 18 steps. Feedback accommodated in the FiberMaster 245601. T&M, 0892 653322. optical time domain reflectometer Interfaces giving flexibility of high resolution and Transducer interface. Oasis High current terminal block. 30A, Function generators. Thandar long-range performance in single and interface connects a microcomputer 500V terminal block 8375 is designed TG2000 units have 0.002Hz to multimode applications. Driven by RS232 port to analogue signals from to accept 4mm2 cable. It has a double 20MHz frequency ranges in eight Motorola 68020 32 -bit technology. transducers such as load cells, strain square profile solder pin, offering overlapping decade ranges with Tektronix UK Ltd, 0628 486000. gauges, LVDT, PH probes and greater mechanical support than adjustments via coarse and fine oxygen probes. Input impedance is 10 conventional units. The solder pin is verniers. They also offer sine, square Real-time oscilloscope. Hitachi or 1000Gí2 with switch selectable copper/tin plated. Enclosed housing and triangle waveforms as well as VC6024 'scope combines real time gain of 1, 10, 100 or 1000. 3D Digital interlock gives 7.5mm pitch. Wieland TTL outputs. Feedback T&M, 0892 and digital storage. 20Msample/s, Design and Development Ltd, 081- Electric Ltd, 0483 31213. 653322. real-time bandwidth is 50MHz. In 886 3668.

352 ELECTRONICS WORLD + WIRELESS WORLD April !991 NEW PRODUCTS CLASSIFIED

Lan interface circuit. MB86951 is available in six models with output mobile radio equipment to 1000MHz proprietary two-phase brushless encoder/decoder is a serial interface combinations of 5, 12, 15 and 24V including low power hand portables designs using rare-earth magnets to cmos device for PC -based Ethernet DC. UL, CSA, IEC and VDE using selective calling, full duplex create the high air gap flux density systems. MBL8392A coaxial approved. Input range is 85 to 265V radio telephones, digital pocket needed for optimum torque and transceiver interlace IC transceiver AC, 100 to 370V DC. On -board input pagers, base station and repeater efficiency. Parker Digiplan Ltd, 0202 device is for Ethernet Ian applications. line filter exceeds VDE/FCC class B equipment. IR Group, 0753 690911. The MB86954 microchannel interface requirements by about 15dB. Dowty 580000.IR Group 0753 580000 unit. Fujitsu Microelectronics, 0628 Power Electronics, 0722 413060. Displacement transducers. D5 -W 76100. Power supplies miniature displacement transducers, DC/DC converters. DB DC/DC -48V to +5V DC -DC converter. developed for submersion in liquids or Multimedia interface. Rave (real- converters, with short-circuit Max650 produces a regulated +5V gases, are hermetically sealed using time audio and video environment) protection facility and automatic reset, 250mA output from -48V. All control electron -beam welding of the multimedia development environment have three input voltage ranges - 10 functions and a 140V, 250mA pnp stainless steel housing. Specially and user interface for the IBM-PC is to 16V, 17 to 34V and 35 to 70V. transistor are on chip. It incorporates designed cable attachments will for industrial uses such as process These 50W open -frame primary a shutdown function to permit output withstand pressures of 2000psi. control and instrumentation. It runs on switched regulators offer up to three to be disabled under logic control. Measurements from ±1 to ±5mm. top of the OS -9000 operating system. isolated output lines in combinations Soft start reduces initial current levels, RDP Electronics Ltd, 0902 457512. Microware Systems (UK) Ltd, 0489 of 5, 12, 15 and 24V. Schroff UK Ltd, and permits safe start-up at full load 886699. 0442 40471. without overshoot. Maxim Integrated Vision systems Products, 0734 845255. Image processor. Imaging system Production test Power supply controller. Kikusui's provides digital storage, real-time equipment unit simplifies the making of automatic Lower cost. AEC series low cost processing and playback of video Wafer inspection. Nidek IM -7 DC power supply systems, either via unregulated power supplies have AC sequences for industrial and security inspects etched wafers during photo- GPIB or sequential control. In GPIB inputs of 110, 220 and 240V, CCTV systems. It uses transputer lithographic processing. Its fused mode it interfaces between host frequencies of 47-440Hz. Load technology and captures images from quartz contact surface gives pin -point computer and power supply. Two regulation is 20% or 3V whichever is pal standard signals, then examines accuracy of movement. Stabilised channels; two supplies can be greater for a 10-100% load change them for specific features such as auto -focus eradicates focusing controlled. Setting resolution is 12bit and output ripple and noise 1V RMS. moving objects or characteristic problems, even with dark or bright for each output. Telonic Instruments Operating temperature is 0-70% with shapes. It stores the images in four visual fields and highly absorbent or 0734 786911 2.5%/°C derating above 50°C. 512 by 512 8 -bit memories for further reflecting surfaces. Wafer exchange Isolation 4kV. Ten units can be processing. Akebia 081-546 4908 time is 2.5s/wafer. Manual positioning High -current supply. Kenwood connected in series or parallel. XP by integral joystick. Dage (GB) Ltd, PD18-10 is a 0-18V and 0-10A unit plc, 0734 835515. 0296 393200. with dual analogue or digital meters and a three -terminal floating output. Programmers Board testing. BoardMaster TSA Voltage setting is via a ten -turn Software upgrade. Intel Flash parts COMPUTER , offers an open architecture test potentiometer. Preset output voltage can be handled on Stratos PC -based strategy for in -circuit, functional and can be switched. Ripple and noise eprom programmers using a software combinational testing up to data rates between 10Hz and 1MHz are within upgrade in the form of a floppy disc. It of 50MHz and offers manufacturing 0.5mVRMS. Thurlby-Thandar extends to full E2 support in 24, 28 Computer-aided design defect analysis, analogue/digital in - Ltd,0480 412451. and 32 pin packages. Stag Cad program modules.. Release circuit, emulation, simulation, Microsystems Ltd, 0707 332148.Stag 1.03 of the HEPA series of cad combinational and functional testing. Computer power supplies. Microsystems 0707 332148 program modules is for switching RF It links to all professional simulator Computer Products power supplies power amplifiers and linear amplifiers target systems. Rohde & Schwarz UK include linear, switched mode. Transducers and driven into gain saturation. They Ltd, 0252 811377. Euromodular, and bench adjustable sensors evaluate performance from RF power units as well as DC -DC and AC -DC Transducers. Isotran transducers are transistors and design, simulate and Digital IC tester. Designed around a converters. Most have approval to UL, for measuring AC electrical variables optimise the power amplifier circuit. Z80A 8 -bit microprocessor, the ABI CSA, VDE, ISO9001 and IEC950 such as current, voltage, power and Claimed to be faster than Spice by a digital tester system features standards. Verospeed, 0703 641111. VARs. Accuracy is typically 0.2% of factor of 1000. Design Automation dedicated LSI ICs to control keyboard full scale. There are two case sizes, Inc, 617 862 8998. and display, and handle information Radio communications either 55 or 150mm wide DIN rail or input/output from the device under products panel mounted. Isolation is 4kV on Computer board level test. It can cater for clocked devices Network analyser. A standing -wave input to input and input to output. products such as flip-flops, latches, counters, ratio bridge makes this device Glade InstrLments Ltd, 0785 662685. Grabber board. Analogic FG/ALU-8 and shift -registers, tri-state or open - suitable for simultaneous video frame grabber board for the collector devices, memories, and measurement of transmission and Alarm thermometers. Thenma D4C 1R PC/AT is capable of real-time 8 -bit interfacing including line drivers, reflection characteristics of panel alarm thermometers are ALU processing and uses a menu - receivers, and opto -isolators. STC components for mobile general purpose mains (240 or 110V) driven dedicated software package Instrument Services, 0279 641641. communications systems. R3763A operated units. They are a digital called Imagine. It has RS170, RS330, covers the range from 300kHz and indicator with an on/off high or low NTSC, pal and CCIR compatibility. Appliance tester. Seaward PAT has a sweep time of 0.5ms per point. alarm/switch rated for 8A loads. Lea Consort Electronics, 0252 871717. 1000 portable unit can be used for Advantest UK Ltd, 081-336 1606. display indicates set point or the earth continuity testing: insulation temperature, with set point adjustable Digital signal processor testing to 500V DC; flash testing Radio ID system. ID2 measures 42 x from front panel. -50 to +1150°C with DSP module. SPT156 measures 9 x selectable between 1.5kV Class I and 32mm and works by sending a two - 1°C resolution, repeatability and 11cm and is built to the Inmos Tram 3kV Class II; a supply voltage load digit ANI signal at the end of each accuracy. Probes from £10.00. ETI, format. Its dual processing design test with a current limit; operation test over. It is programmed by splash 0903 202151. combines the 10Mips power of the from 0 to 3.2kVA at supply voltage; pads for any of 256 identities and has T400 or T805 transputer with the DSP and leakage test. A memory permits only five connections to the radio, Single -axis brushless servo. PS7X capability of Motorola's DSP56001 recording of up to 400 sets of tests. taking minutes to install. is supplied ready -to -run, containing processor. 1 or 4Mbyte of dram as STC Instrument Services, 0279 Communication Development an all -digital indexer/drive unit with system memory and 96Kbyte of 641641. Specialists Ltd, 0256 83528. built-in power supply, brushless motor fastsram. Sunnyside Systems Ltd, with integral encoder, and 10ft 0506 460345. Power supplies Single unit tester. Marconi 2955R interconnection cables. The .rotor Switching 40W. Power General Flu3- radiocommunications test set has all can handle peak torques of up to foLr Image capture card. Entry level 40 series of universal input, triple functions for transceiver testing in a times its continuous rating and has a multimedia card MicroEye IC can output, 40W switching power supplies single unit. It can test AM, FM and PM top speed of 7500rpm. Motors are capture a video image and

April 1991 ELECTRONICS WORLD+ WIRELESS WORLD 353 NEW PRODUCTS CLASSIFIED

incorporate it into a PC graphics performance. Based on a 16MHz Industrial workstation. 2900-RM is above. Keithley Instruments Ltd, 0734 display. It has been enhanced to 80386SX microprocessor, it keeps rack -mounting with an integral 19 -in 575666. accept single field video images from hardware and software compatibility colour screen. Complex plant mimics video recorders which eliminate the with existing 16 -bit systems and lets or trend graphs can be displayed in Autorouter. The Maxroute fully flicker experienced when capturing AT users run multitasking operating up to 1024 x 768 Super -VGA interactive shove router is available pictures from a moving video source. environments such as Unix386, resolution. It is based on the 386SX from Lloyd Doyle with a PADS Digithurst, 0763 242955. DESQview 386 and Windows 3. or DX processor with I Mbyte ram, interface. In routeing a board it looks Microway (Europe) Ltd, 081-541 one 3.5 -in floppy disk and 40Mbyte for ideal paths that could be made Solid state disc. PC form -factor plug- 5466. hard disk with 19ms access time. available and then clears the room for in cards perform all the functions of Front and rear connectors for the new route at the location. Lloyd conventional floppy or hard disks with Development board. Cmos keyboard. 110V/60Hz or 220V/50Hz. Doyle, 0932 245000. access times 50 times faster than a microcomputer development board for £5000. SD-Scicon UK Ltd, 061 491 hard disk. For use where a PC is the Mitsubishi M50747 works with a 3683. DSP toolset. InterTools 96002, for used for fixed tasks such as machine PC running a text editor, assembler creating and debugging software control and monitoring, they can also and appropriate communications Development and applications for embedded Motorola let networked PCs boot without a software. The board carries an evaluation DSP96002 processors, is a totally floppy disk. Fairchild Ltd, 042121 M50747SP extendec microcomputer, In -circuit emulators. IceMaster in - integrated C environment. It can 6527. 8Kbyte of battery supported ram, circuit emulators replace the Microlce implement advanced optimisations, 16Kbyte of eprom, reset, crystal clock and Metalce units. The IceMaster is in -line assembly and instruction Single -board computer. XP 286 and and RS232 transceiver in a 100 x for 8051 and 68HC1 1 microcontrollers coalescing techniques. Loughborough 386 single -board computers are 160mm board. RCS Microsystems and has a windowed user -interface. Sound Images, 0509 231843. software compatible with the PC and Ltd, 081-979 2204. PC XT/AT or PS2 compatible. Reflex AT and have full VMEbus Technology Ltd, 0494 465907. Development tool. Microtec has master/slave interface and system released an 88K software controller functions. They run at 16 or Computer systems Software development tool chain to produce 20MHz. Local system memory is Rack -mount computer. PC825 rack - PCB autorouter. Version 7.7 of the and debug highly optimised code. It either 512Kbyte or 2Mbyte dram mount computers can act as low-cost Vutrax PCB system includes full Unix addresses the Motorola 88100 and expandable by daughter card to SBC stand-alone controllers or file compatibility under X -Windows, a consists of C compiler, C source level 4Mbyte. HTEC Ltd, 0703 servers and data acquisition and gridless autorouter and schematic simulator and debugger and 581555.1-1TEC 0703 581555 management computers. Features capture enhancements. Vuroute is a assembler. The C compiler is fully ANSI conformant and takes full advantage of the 88100 risc r - [r1,1K Kr[t rop[I architecture. Microtec Research Ltd, «[ 31" _ ni.___m""0"1«: 0256 57551.

111.115 c emitrrlF'.-.c-. cab J deb. . - r s rm _._ lit sxt> Schematic capture for large PCBs. 7.11~ toulI yl! nab An enhanced version of schematic /Ab t0000000000 7L _ r capture software Pads-Logic is nwelaa ylii particularly suitable for large PCB designs. Upgrades include 4i,o/r ropa rac[r hierarchical design capability, design et.11!" 115 Ll orientated database, automatic gating .a . and pinning, and support for a range r . . o 15/5 : 4.=. Ir of popular simulation and cad layout i . , I ` tools including P -Cad, Futurenet, Rlax yet .....o .r , . o - . , 11 q-!0 Cadstar, P -Spice and Susie. Library w,iNlx tlY of 5000 electrical devices and parts. n;f 47 Lloyd Doyle Ltd, 0932 245000. . 1h:UMIIi I B - xl v6rO70G ;3 ,S= . . _ .,. ( u t ;1 Data logging. Solar is a real-time PC \ 011 03. utlr ..r Ili-!III ill based program for recording In . equipment signals. It has multi- 1 . . .. DJ 1 .., ; 15;.1:;' 1i M.:' tasking, fail safe -down I al 0 ___ .n...yF!_ power , r 017 - 1 rer protection, password access control, 00000óó000J[, - u graphical trend displays, help screen 1 ó000000o0oa,4 G ` r . C , facilities, on -demand reports and data r- rptM . w t. - ;,f 111111-"" export. User -definable algorithms can be incorporated for calculating values prior to storage or display. Nano Computing Ltd, 0606 49937. Pocket Rocket from LSI Logic, an evaluation board for the LR33000 Workshop management. Scantrax, Evaluation board. An evaluation include ISA, eisa or MCA gridless rip -up and retry autorouter is designed to give control over board for the LR33000 embedded motherboards, eight -slot eisa or 4 to with specific bus, routeing and administration of the repair workshop processor, the Pocket Rocket, board 15 slot ISA backplanes, and four optimisation phases for conventional to minimise paperwork. It uses measures 8.6 x 15.7mm. It can be device drivers all with shock mounts. and surface mount cesigns. conventional keyboard and bar-code used in hardware and software Comcen Technology, 0792 589988. Computamation Systems, 0525 input to record receipt of repair items, evaluation as well as for prototype 378939. job status, technicians' time and assistance. It contains 1Mbyte of Industrial PC. 2902 -FS industrial PC materials used. Full traceability of dram, 128kbyte of eprom, two serial is for desktop use and has a 19 -in Data acquisition software. For 386 spares used and repair item history is channels and a 96 pin expansion screen. It uses the Intel 80386 and is and 486 -based PCs Viewdac gives retained. Orac Information Systems counter. LSI Logic Europe PLC, 089 drip proof and fan filtered in a rugged users access to features such as high Ltd, 0734 772233. 926 90 30. metal case. Disc dr,ves and controls processing speed, 32 -bit addressing are protected by a locking cover. VGA and multitasking. It uses a window Plug-in accelerator. The graphics standards give up to 1024 by environment and runs on Dos 3.0 or FASTCache-SX plug-in accelerator 768 super -VGA resolution with 16 card from Microway enhances 16bit colours. SD-Scicon UK Ltd, 061-491 Editorial survey: use the infomatlon card to evaluate this article. Item O. 286 IBM compatibles with 32 -bit 3683.

ELECTRONICS WORLD+ WIRELESS WORLD April 1991 354 R F 4NNECTIONS

Exploiting the spectrum above 30GHz

Despite R&D effort and official encour- from information coating out of two IEE created ITC will issue "local delivery" agement from the Radiocommunication colloquia ("Radiocommunications in the licences to cable operators without speci- Agency of the DTI. practical civilian utili- range 30-60GHz" and "The National fying the technology. thus permitting sation of the radio spectrum between 30 Radio Propagation Programme") and the cable or MVDS or a mixture of both to he and 60GIIz for communications and 26th Appleton lecture given by Roger used by franchise holders. broadcast distribution in the UK seems Byrne (ITC. formerly IRA). A working group has recently been destined to proceed relatively slowly. The IBA work on MVDS has included formed by the Radiocontnmunications An identified practical application, field trials in both millimetre -wave bands Agency of the DTI to assist the DTI. ITC, however, is to link mobile cellular radio and the upper part of the 11.7-12.5G11z industry and potential users in formulating control centres and their base transceiver broadcast band reserved primarily for broad plans for the use of MVDS at sites at 38GHz. GEC -Plessey at Coventry DRS. 40G1 I z. are to introduce later this year short-range The 40.5-42.5G1Iz band promises to be SE Pike and John Lothian (NTL) have 38GIIz link equipment providing two the harmonised frequency band for pointed out that, despite limitations due to BMhit/s digital channels. European N VDS: at I2Gii¿ it is now currently available technology and attenu- But the future of 40G11z broadcast dis- recognised that there would he insuffi- ation by rain and atmospheric gases (oxy- tribution systems (MVDS) seems less cer- cient spare spectrum to provide a 20 -chan- gen vapour). it is possible to obtain a use- tain. with cable operators so far showing nel MVDS system equivalent to modern ful cell size of about 3.8knt. Using a relatively little interest. despite field trials broad hand cable systems. monolithic low noise amplifier in the by BTRL (British Telecom Research NTL (formerly IBA Engineering receiver would increase this to 5.6km and Laboratories). IBA and industry. Division) is now concentrating on the pos- coverage would he achieved using a trans- Such at least appears to he the case sibilities for the 40Gllz hand. The newly - mitter with a sector horn on one side of

Mobile comms confusion may deter users Commercial success of the existing analogue Cellnet and than 900MHz to Doppler shift and the consequent ntultipath Vodafone networks - over I million subscribers, though with spreading of the received pulses. growth rates currently affected by the recession - is seen as an Some bench -stark figures given at the colloquium by Philip encouraging sign for pan-European harmonised digital systems. Gaskell (Unitel) indicated that, whereas in rural areas GSM900 But at a recent IEE colloquium, Dr Christopher Queree (MVA should be satisfactory at speeds up to about 250km/h, the Systematics) warned that "the complexity and range of mobile equivalent speed for DCS1800 would be about 130km/h sug- communication offerings (present and future) is confusing to gesting that there might, for example, be problems in using the users and smacks of being driven by technology". system on high-speed trains. Dr Queree's worry was that, having chosen one mobile sys- In hilly terrain and urban (car) areas there should be little dif- tem a user will be reluctant to take another. Some key aspects ference in practical performance with figures of 100km/h and of mobile services, such as traffic information, were not valued 50km/h respectively for both systems. Urban (pedestrian) per- highly, he said, partly because at the moment the quality of formance at 3km/h iGSM000) and l.5km/h (DCS1800) were such information is not as high as will be needed for effective not expected to present practical problems. real-time fleet control. "In strictly cost -saving terms, the returns (to the user) of Architecture for mobile terminated short -message -service mobile radio services are often not brilliant," he said, and providing store -and -forward transmissions of up to 83 char- pointed to a US study of truck tracking suggesting a return of acters on the signalling channel. about 1% on an investment of around 5% of turnover. Dr Queree concluded that success (of pan-European systems) will neither be guaranteed nor easy. PCN, being initially a UK phenomenon, is not yet seen in OPERATOR BUREAU quite the same way. According to Dr Queree its main attraction will be to extend mobile communications to a much wider mar- X.400 ket. PCN on I.8GHz with its small cell size and digital technol- SYSTEM ogy is capable of offering specialised features nor available with many of the established systems. but will require very PRIVATE WIRE large investment in the infrastructure of the networks, particu- larly if system operators each provide extensive coverage in M.r{-kIr. 11k rural areas as well as urban centres. Sig eWllln{ link Mobile operation at 1.8GHz is significantly more susceptible Inr.rr.{Winn link

April 1991 ELECTRONICS WORLD+ WIRELESS WORLD 355 R F CONNECTIONS

the cell, transmissions using FM. bility and potential of GaAs MMICs. But available to carry high data rates. work at Key factor for 40GHz MVDS and for BT themselves are precluded from large- Roke Manor in conjunction with Bristol many local telecommunications services scale manufacture of consumer devices University indicates that short range mil- at around 38GHz - or in the high oxygen and production would need to involve the limetre e -wave channels show delay absorption band around 60GH7 (with its semiconductor industry. At present virtu- spreads of 50ns - limiting transmission excellent frequency -reuse potential) - ally all the available low-cost millimetric- rates to less than SMsymhols/s without remains the development of mass-pro- wave components come from overseas resort to equalisation - and that power duced, low-cost millimetric-wave compo- suppliers. decays more rapidly with increasing delay nents. These include monolithic IC About 20 months ago a technical work- than at lower operating frequencies. devices and use of such transmission -line ing party on millimetre -wave propagation For hand-held transceivers, Doppler structures as Finline, Microstrip and was set up (chairman C J Gibbins. RAL) spread would seem to present problems Dielectric Image Line rather than wave - to serve as a forum for bringing together that have not yet been fully investigated. guides machined from solid metal. activities in industry. academia and gov- Portsmouth Poly has been investigating TE O'Ciardha of (BTRL) reports the ernment. Its aim was to encourage pre - indoor propagation including reflections successful development of 39GHz low competitive collaboration and co-opera- from signals propagating through walls noise amplifiers, suitable for both RF pre- tion between various groups, as a channel and hours. amplifiers and local -oscillator amplifiers. to direct technical problems from the user Generally. the primary problem appears to using GaAs millimetre -wave monolithic community to those able to provide solu- remain that of cost reduction in a chicken - MMIC technology with 0.31.1m -high elec- tions, and as a vehicle to provide guidance and -egg situation: prices won't come tron mobility transistor (HEMT) devices on direction for future work. down until there is large-scale production having a yield of about 50%r. 15d13 gain and this cannot happen until there are and a noise temperature of 8.5dB. assured markets. BTRL believes that such LNAs could Still problems to be faced he mass-produced within the range of Clearly, there is still considerable work Editorial survey: use the infomation consumer budgets and represents a signif- needed before full use can be made of card to evaluate this article. Item P. icant advance in demonstrating the feasi- these frequencies. Though spectrum is

Working in the rain

It has become clear that work on mod- elling millimetre -wave propagation is rather more complex than originally RECEIVERS TRANSMITTERS anticipated. Rain attenuation, particularly from very fine droplets, is proving 55 GHz greater than CCIR prediction's would DATA 95 GHz 9 km suggest. COLLECTION Rutherford Appleton Laboratory COMPUTER 16 (RAL) has established experimental ter- at over a dis- restrial links Chilbolton 57GHz 57 GHz R-- tance of 500m and more recently 9km. The 500m 37GHz work has been extend- PROCESS 97 GHz 97 GHz ed to 57, 97GHz and infra -red 135 and CONTROLLER 135 GHz 500m 135 GHz TEMPERATURE 210GHz with the 9km path currently at 55GHz, to be extended also to 95GHz. 210GHz C>1210GHz HUMIDITY RAL also uses its 3.075GHz dual - 104 l0µ DEW POINT polarisation rain radar at Chilholton to develop better models of rain -drop size 0 6 0=10 6 DISTROMETER distribution in work directed at optimis- + REFRACTOMETER ing propagation predictions, including rain attenuations, at higher frequencies PRESSURE than have been attempted hitherto. r WIND VELOCITY

Block diagram of the millimetre -wave HAIL/SNOW RAINFALL RATE experimental system at RAL, Chilbolton.

356 ELECTRONICS WORLD + WIRELESS WORLD APRIL. 1991 Meet the Embedded Controller Family J B Designs announces a complete range of microcontrollers for embedded applications. All RTC controllers are designed to run with MC -Net software where the family is distributed all over the plant, and have an expansion socket for connecting the wide choice of I/O expansion modules to precisely meet your applications requirements. RTC31/52 t, yrtnr'tttirhh!!L EMB286 8031 or 80052 -Basic processor w., : 6. .v:^ PC -AT technology applied to embedded control Up to 64K bytes of RAM/EPROM H 10MHz 80C286 AT An RS232/RS485 port Floppy and hard disk interface 12 parallel I/O lines Graphic LCD interface _ Program in Assembler,' C' or Basic On -board bootable solid state disk "oo... Size 3.5 x 3.5' ,.. Built-in parallel and RS232/485 lines IBM AT and matrix keyboard I/F's fri RTC180 9 MHz 64180 CPU I Up to 96K bytes of RAM/EPROM/EEPROM One full -duplex RS232 port and one RS485 port 8/10 bit 8 channel A/D converter 24 TTL parallel I/O lines Use Multitasking Basic, 'C', Modula -2 or Assembler Size 3.5' x 4.5' COMING

RTCV25 SOON 9MHz PC compatible V25 CPU Up to 384K of RAM/EPROM Two RS232/485 serial ports Time -of -day clock 8/10 bit Channel A/D converter If you want more details on the ULTIMATE embedded 32 TTL parallel I/O lines controller, then pick up the phone and call us - Use JPI Modula -2 or Microsoft 'C' because we are designing for your FUTURE -TODAY! Size 3.5'x5'

J B Designs & Technology Limited 15 Market Place, Cirencester. Gloucestershire GL7 2PB. UK DESIGNS Telephone (0285) 658122 Fax (0285) 655644

CIRCLE NO. 154 ON REPLY CARD

AC CIRCUIT ANALYSIS SMITH CHART CAD ANALYSER II £195 Z -MATCH II £195 t- Evaluate the Metres innards:

Generator= 11.2233 } } performance of

your designs Lod. 1.2767 } prior to breadboarding. Make Gee fib 11.80 modifications to C C FF: them and assess the new 1-_.-,, performance in Guile ills) i H11 If11 .....1....:....r....: r....:.. .r....:....1..... minutes, rather Ta: 511 OM 11.51lhil.1011 LG7Ma than hours or Preq: 19e.11 Mle Iwred.,cr01_.:

days. Dielec.constant.1.130 ANALYSER II can save thousands Z -MATCH II takes., the drudgery out of RF matching of pounds in test problems and includes many more features than the equipment alone. standard Smith Chart. Provides solutions to matching problems using Runs on transmission line transformers, PC/XT/AT/286/386. stubs, discrete components etc.etc.. EVALUATE DESIGN MODIFICATIONS IN Supplied with comprehensive user instructions including MINUTES! many worked examples. For full info, Phone, Fax or use enq. card: - Number One Systems Ltd. IL The CAD Specialists REF: WW, HARDING WAY, ST.IVES, HUNTINGDON, CAMBS, ENGLAND, PE17 4WR. Telephone: 0480 61778 (7 lines) Fax: 0480 494042 International: +44-480-61778, I'Fax: + 44-480-494042 ACCESS, AMEX, MASTERCARD, VISA Welcome. CIRCLE NO. 155 ON REPLY CARD

April 1991 ELECTRONICS \1ORLI)+V I REI ESS \\ ORI I) 357 081 081 661, 661 *Ila 8469 CLASSIFIED 8640 ARTICLES FOR SALE

TO MANUFACTURERS, WHOLESALERS, e . 'VALVES AND C.R.T.s BULK BUYERS, ETC. (also Magnetrons, Klystrons, Transistors) LARGE QUANTITIES OF RADIO, TV AND ELECTRONIC COMPONENTS FOR DISPOSAL One million valves in stock. Obsolete types a speciality! Fax or phone for SEMICONDUCTORS, all types, INTEGRATED CIRCUITS, TRANSISTORS, DIODES, quote. RECTIFIERS, THYRISTORS, etc. RESISTORS, C F, M/F, WAN, etc. CAPACITORS, Special prices for wholesale quantities. SILVER MICA, POLYSTYRENE, C280, C296, DISC CERAMICS, PLATE CERAMICS, etc. Orders from government departments, overseas etc. most welcome. ELECTROLYTIC CONDENSERS, SPEAKERS, CONNECTING WIRE, CABLES SCREENED Many other types in stock. Please enquire re any type not listed. WIRE, SCREWS, NUTS, CHOKES, TRANSFORMERS, ETC ALL AT KNOCKOUT PRICES CATHODE RAY TUBES M28.13LG c45.00 1CP1 £29.50 D13.611GH t59.00 F16.101GM C75.00 M31.182GV [45.00 -Come and pay us a visit ALADDIN'S CAVE 12CSP4 C35.00 D13.630GH £59.00 F21.130GR [75.00 M31.184W £55.00 107414 C45.00 014.200GM C75.00 F31.12LD C75.00 M31.190GR C45.00 TELEPHONE 081 445 0749/445 2713 30780 C95.00 D16.'00GH97 £65.00 LF708 C75.00 M31.191W t55.00 8931 (W.H) POA DG7-5 £45.00 M7 120W C19.50 M31 325GH £35.00 R. HENSON LTD CME822W C7.00 1307-6 £45.00 M14.1000M £35.00 M38.100W t59.00 CME1523W £9.50 DG7-32 f55.00 M17151GVR.... C175.00 M40.120W .. t59.00 21 Lodge Lane, North Finchley, London N12 8JG. CRE1400 C29.50 DG7-36 £55.00 M21 11W £55.00 MV6-5(Mul) £50.00 (5 minutes from Tally Ho Corner) D9.110GH C45.00 DH3-91 [50.00 M23 112GV £45.00 SE5FP31 f45.00 D10.220GH £45.00 E723(EEV) POA M24 121GH £55.00 T975D f75.00 D10.230GM £45.00 ECR35 £39.50 M24.122WA f55.00 VLS429AG POA VALVES Prices on application. Please enquire re any type not listed below. _ A2426 Maz M8136 Mu! VL5631 J/V/C.i+ f ECC804 6BJ6 A2521 ECC81 M8162 Mul Z759 6BM6 C1149-1 ECCet Spec M5138 Z803U 6CH6 01166 ECC82 MagBnetrons Y644 6CJ6 cCS1 ECC82 Spec O PC900 10355 6F33 Cooke International CV TYPES: Many ECC83 PCC89 2K25 61.600 in stock Not all ECCB3 Specp O PD500 3828 6SL7GT DO YOU WANT USED SCOPES, SIGNAL GENERATORS, listed below. Please ECC88 PL509 3C/800E 6SN7GT Inquire. ECC88 Spec 0 00V03-10 3J -160E 12BH7 POWER SUPPLIES, POWER METERS, DVM's, OSCILLATORS, CV488 ECC804 00V03-10Mul 4-65A 12E1 CV1881 EF39 00V03-205 4.1255 Eimac 13E1 ATTENUATORS, TEST EQUIPMENT. CV2355 EF73 00V03 2OA EEV 4-4005 19A05 CV4014 EF91 o0V06-405 4028 211 Contact: Cooke International, 4, CV4024 EF92 00V06-400 Mul 4CX2500 805 Unit Fordingbridge Site, Main CV6087 EF86 Sion-ens 0Y3-125 4CX250BC 807 Road, Barn ham, Bognor Regis, West Sussex P022 OEB. cV718o EF93 0Y4-250 4CX350A 8115 CX1140 EF95 OVO4-7 4CX1000A 813 Tel: 0243 545111. Fax: 0243 542457. DA42 EL34 RIO 4CX5000A 4635 DET22 EL38 SU2150 5B -254M 5763 DET23 EL81 TT21 SB-255M 63365 Open Mon to Fri 9.30am-5pm DF91 ELB1 Mol S11E12 58-257M 6973 EBOL ELe4 1003.106 58-258M 8056 Wide range of items available. Visit our walk -round bargain E83F EL5070 1Y4-4005 5U4G 8122 E88CC GV501 U19 5V4G Sockets: store. Send for lists. E180F Klystrons UBC41 BAKSW B9A PCB E810F KT61 UCL82 6A56 B9A chassis EC158 KT81 UL41 6840 Octal Chassis ECC35 Mol KT88/6550 UY85 68H6 Many others FIELD ELECTRIC LTD VA222A Testing to special quality - Military/CV, industrial etc available on request 3 Shenley Rd, Borehamwood, Herts. WD6 1AA 081 953 6009. Fax 081 207 6375. We buy & sell Computers at Computer Hardware, Power BILLINGTON VALVES Unit F2, Oakendene Industrial Estate, Near Horsham, RH13 Supplies, Test & Measurement Equipment Special Offer 8 bit Sussex 8AZ. Callers by appointment only. EGA cards from £18.95 16 WDC bit from £8.95 cp £1.00 Fax: 0403 865106 Telex: 87271 PRODSS G Tektronix 465B O'scope 100MHz £460 inc VAT C/P £24.00 in Telephone: 0403 865105 Cal: Mail order or callers welcome. Send SAE for List. Min. UK order £20,+ VAT. Min. Export order f50 + carriage.

Technical & Scientific Supplies LCR Bridge -AIM Datebridge 401 £175 HP Thkletm Printer -New Boxed £185 Attenuator. 0.10048 Hatfield/RS 610.506 MURPHY TYPE A72 BULK Unused 098 GOLLEDGE BUYING LISTS PCM Decomut'r Doce,,, Systems 7103 NRZ/ ELECTRONICS McMICHAEL Blphase £2100 CRYSTALS Send £1 stamps + large SAE: Galvanometers for recorders - OSCILLATORS -FILTERS UV various, from £15 AF Power Meter. Dymar 585 £110 Comprehensive stocks of standard items. Over SUPER VOX 650 stock lines. Municipal Metals & VHF Signal Gen r Pye SG3V 70-170MHz. 3 ranges, Specials made to order. Supplies AM and FM Mod. Tatry but fully operational £55 OEM support design advice, prototype quant- MULLAND TYPE M.U.35 Transistors MP3731 320V 10A PNP 103 4 for E1 ities, production schedules. (Electronics) Pye FM1OBV.6 Transceivers, pair ex working Personal and capon orders welcome. For information and offers system, remote control, hailer etc but as seen. £98 SAE for our latest product information sheets. 21 Wilshaw Street Hire available on some eourpmenrs GOLLEOGE ELECTRONICS LTD Tel: 0460 73718 please reply to All prices exclude carriage and VAT. Merrion, Somerset, TA16 5NS Fax: 0460 New Cross SE14 6TN Lists now available, please write/fax/phone:- 76340 Box No. 2611 Technical & Scientific Supplies, PO Box 19, Hythe, Southampton, Hampshire. SO4 650, Tel:- (0703) 848 666. Fax:- 107031 89 7 079 ARTICLES WANTED WANTED Receivers, Transmitters, Test STEWART OF READING WANTED Equipment, Components, Cable 110 WYKEHAM ROAD, Test equipment, receivers, WANTED: VALVES TRANSISTORS and Electronic, Scrap. Boxes, READING, RG6 I PL. valves, transmitters, I.Cs (especially types KT66. K1'88 TEL: 0734 68041 PCB's, Plugs and Sockets, components, cable and 1'X4, I'X25). Also plugs. sockets and Computers, Edge Connectors. FAX: 0734 351696 electronic scrap and quantity. Prompt service and cash. complete factory clearance. If possi- TOP PRICES PAID FOR ALL TYPES OF TOP PRICES PAID FOR ALL ble, send written list for offer by TYPES OF SURPLUS M& B RADIO ELECTRONICS EQUIPMENT TEST return. Billington Valves, phone 0403 EQUIPMENT, COMPUTER 86 Blshopgate Street, A.R. Sinclair, Electronics, Stockholders, Leeds LS1 4BB. 865105. Fax: 04(13 865106. See adjoin- EQUIPMENT, COMPONENTS 2 Normans Lane, Rabley Heath, Welwyn, Tel: 0532 435649 ing etc. ANY Fax: 0532 426881 advert. Herts AL6 9T0. Telephone: 0438 812 193. QUANTITY. 103 8858 Mobile: 0860 214302. Fax: 0438 812 387 780

358 April 1991 ELECTRONICS WORLD+\1IRELESS WORLD Oasis Data Converters INDUSTRIAL DATA MONITORING Low-cost precision interfaces and multi -tasking software hardened for industrial data logging and process monitoring INTERACTIVE PROCESS MONITOR SOFTWARE

Calibrates and filters measured data Compensates and linearises thermocouple data 4\ R Converts data to engineering units Calculates virtual channels. derived from real roo; Configurable displays; charts. line, bar etc. 1 Run-time display selection by operator Automatic archive to disk with run-time replay Concurrent printouts including colour charts Full range of analysis software for data files INDUSTRIAL ANALOGUE INTERFACES

16, 32. 64 and 96 channel units 1 30(1V isolation between channels 500V isolation from host computer 2OmV- 10V full scale in nine ranges - . ' 2(1(1V full scale ranges option Direct connection thermocouple conditioning ®.T --.T :!.! 4-wire RTD and resistance conditioning I(I/20mA current loop conditioning - - 25k samples/sec on -channel throughput l ,, 4k samples/sec across channel read rate

The Street, Old Costessey, Norwich NR85DF Tel: 0603 747887 Design Consult ancy

CIRCLE NO. 156 ON REPL F" CARD APPOINTMENTS THE BRITISH LIBRARY NATIONAL SOUND ARCHIVE

ENGINEER TECHNICAL TRANSLATORS (German English), to The National Sound Archive is the national collection for all kinds WRITERS AND ADVISORS of recorded sound. The collection includes material on carriers Sought for a new publication about the practice and theory of PC - ranging from wax cylinders to digital audio tape with an based measurement and control techniques. international subject coverage including various musical We need to build a team of experts who have a combination of traditions- literatt.re, the spoken word, and wildlife sounds. skills: Listening, Information, and Transcription Services are provided for public access to the collections. * fluency in technical German the * ability to design measurement and control software for the PC Applications are invited for post of Engineer (Museum Technician Ill) in the Conservation and Technical Section. * up-to-date technical knowledge You will be responsible for the maintenance of the Archive's * good contacts in the industry audio equipment which includes signal processing and mixing * ability to write clearly for process engineers desks, amplifiers, record decks, tape recorders, CD and DAT If you are interested, please fax or send CV and letter to: players, and some video equipment. Much of the work will be Elizabeth Evans done by the Engineer but maintenance contracts and call -out Head of New Product Development engineers may be used where necessary. You will also be WEKA Publishing Ltd expected to meet occasional requests for the construction of The Forum, 74-80 Camden Street small customised devices for applications within the Archive. London NW1 OEB Applicants should oreferably have experience in the professional Tel: 071 388 8400 recording industry, and should have proven technical skills. You Fax: 071 388 0692 should be thoroughly familiar with a range of traditional analogue equipment as well as with professional and domestic digital systems. For further information telephone Peter Copeland on 071-589 6603. Salary range £11,188-£12,972 including £1,750 London Garibaldi-RF & Microwave weighting. Annual leave 22 days (rising to 25 after 1 year's service) plus 101/2 public and privilege days. We are the specialist agency for 'Radio Frequency' design or test Engineers working from 1MHz to light! We have hundreds of top Applications (to be returned by 5 April 1991) from Personnel positions throughout the UK, working on RF mobile comms (GSM, (Recruitment), Administration, The British Library, 2 Sheraton PCN, CT2), opto, satellite, mm -wave & microwave projects. Street, London W1V 6BH. Tel 071-323 7331. Please contact our consultant Simon Luttrell MSc on 0494792592 The British Library is an equal opportunity employer. 160 Bellingdon Road, Chesham, Bucks. HP5 2HF.

April 1991 ELECTRONICS WORLD+WIRELESS WORLD 359 33MHz 386 Top performance motherboard with 64K cache built in. Set up disk. 8 expansion slots. AMI BIOS. MATMOS 286, 386 memory upgradable to 16 Mbytes on board and 80387 socket (799 (carr (5). 25MHz 386 motherboard. 80386 cpu, Landmark speed 33MHz.. accepts up to 8Mbyte SIPPS HAM, otherwise as and 486 SYSTEMS above L499 )carr (3.50). 12MHz AT motherboard, 80286 cpu. 8 expansion slots, full AMI bios with diagnostics etc., 80287 socket, manual. Landmark speed of 16MI1z, accepts up to 4Mbyte of SIPPS RAM on board (99.00 (carr C3.50). WIDE RANGE OF ADD-ONS 1 Mbyte RAM IOr 80286 or 80386 (49 50 (please state chips, SIMMS or SIPPS(. 10 MHz 80287 maths coprocessor 0129. AT Multi I/O board with 1 parallel. 2 serial. 1 game, 2 floppy, IDE hard drive E37.50 AT 00 card, parallel, serial, game (17.50. AT floppy disk controller £15. Mono graphics card MATMOS 286 AND 386 HIGH PERFORMANCE COMPATIBLE C14 50 all carr, (2). COMPUTERS KEYBOARDS XT compatible quality keyboard at very low price (9.95 (calf £3.50). 16MHz 286 system: E349 plus VAT MOUSE A quality system using the industry standard 80286-17 processor, running at a Landmark speed of Microsoft compatible, serial with software C34.50 (carr (3(. 16MHz; clock speed 12MHz. Complete with 1 Mbyte RAM expandable to 4 Mbytes. Serial and parallel MONITORS MONO (Centronics) ports, 101 keyboard mono graphics card. 1.2 Mbyte 525 inch floppy drive. floppy - 12 inch Xerox Hercules very controller, IDE hard drive controller (add C20 for MFM or RLL unless purchased with Matmos hard paperwhite; smart case with tilt -and -swivel base. particularly good, user.friendly high res display (59.95 (6.50). drives.), (MFM and ALL options), eight expansion slots (3-8 bit, 5x 16 bit). AMI bios with full setup (car, 12 Inch Hercules amber; 12 volt suppl'r )psu needed) modern with routine and diagnostics including HDD formatting, well made stylish case with space for up to three case tilt and swivel base 029.50 (carr (5). 14 Inch VGA paperwhite; smart case, tilt -and swivel base L89.50 E6 50). 5.25 drives and two 3 5 inch drives: lock, front panel switches full manual (carr and LEDs, included. MONITORS 33MHz 386 system: E779 plus VAT -COLOUR 14 inch 1024..768 VGA multisync. Same system as above but with state.of-the.art 386 motherboard. Uses full spec. Intel 80386.25 Latest VGA. 0.28 dot pitch. Displays up to 1024a 768 at a very high quality. (279 )carr L10( running at a Landmark speed of 33MHz; clock speed 25MHz. This is not a 386sx but has a full 32 bit 14 inch 640 by 480 VGA good quality fully compatible lex. dem) (179 C/0(. CPU. Comes with 1 Mbyte of RAM upgradable to 8 Mbytes. Also available in quality full height tower (cart case at E879 plus VAT Carriage on systems L14 plus VAT. See below for add-ons. HITACHI CAD COLOUR MONITORS 20 inch mutt isync. CM2085M From VGA up to 64KHz at 1280 by 1024 (ex dem.( (899. FLOPPY DRIVES 20 inch fixed frequency 48 KHz CM2086A1.D lux dem.( (350. Internal 20 inch fixed frequency 64 KHz CM2086A3-EX (ex dem.) (350. 360K 5.25 inch standard quality IBM half -height chassis drive (29.95 )carr E3.50). 16 Inch fixed frequency 64 KHz CM1686A (new( (299. 720K 3.5 inch NEC FDt036 30mm drive For XT or AT's (32.50 (cart (3). Fitting kit for 5.25 inch space (p.o a for carnage for above) (8 49. LASER PRINTER 7206 3.5 inch Citizen OSU45A true third -height drive (37.50. Fitting kit for 5.25 inch space 08.49 (carr Acer -76 II C3). LP HP Laseget compatible, 6 drain., 300 x 300 DPI. 512K expandable to 4.5 Mbytes, standard Centronics interface, with auxiliary paper tray giv ng paper capacity of 400 sheets or two paper sizes (20). 1.44 Mbyte 3.5 inch third height drive for ATs (49.50 (car, (3). IBM standard floppy disk drive cable CO. (599 (car, External DIGITISERS (Exdem.) 720K cased Standard 720K 3.5" in smart case with cables to suit Amstrad 2286 series of machines. Hitachi HDG 12120: 12 inch by 12 inch PC compatible industry standard interface, supported by all PC (39.50. Cable adaptor kit to enable use with standard ATs (12.50 (carr (3.50(. applications packages o/fenny digitiser input (125 (carr (6). Hitachi HDG1717D: 17 inch by 17 inch version of above £1751 carr C6). HARD DISK DRIVES, etc Stylus pens, pucks and accessories for above available from stock 20 Mbyte ST125. 1 Seagate 3.5' 28 msec. MFM hard drive: latest, fast, silent technology (129 (carr (4). VGA CARDS 20 Mbyte Miniscribe 8225 24 msec 'state of the art' hard drive with embedded Controller and all cabling 16 bit VGA card. 256K. all emulations, up to 800 a 600 with software to run all major packages. Oak chip set. to connect straight to 16 bit AT slot. 5 25 inch, half height (159 (car, C5). (129 when ordered with 286 Switchablo for use in XT's (74 95. and 386 systems. 16 bit designer VGA card, all emulations up to 800 x 600. 256 colours with 512K video RAM. Paradise chip -set 40 Mbyte Western Digital 5848 RLL half -height 3.5 inch drive in 5.25 inch chassis (179 (cart E4). with software to run with all major packages, XT switehable. (99.50. 50 Mbyte 157R Seagate ST 3.5 inch 28 msec FILL (209 (carr E4) or available as hard card for Amstrad. 16 bit 1024. 768 super VGA card Very high resolution with 512K and software. Full manuals and disks for XT AT or £229 (car' £5). compatibility Tseng chip set (119 1 Mbyte (139 (car, on cards C2.00). 94 Mbyte Seagateltmprimus ST2106E half height 5.25 inch 16.5 msec. ESDI drive with controller (299 (carr E5) FAX CARD HDD cable set (5.00. Plug into PC expansion slot. Giving powerful fax features: ATS Cipher BT approved Group Ill intelligent receive/ transmit, with multiple output and cal scheduling. With disks, cables and full user manual £169 (carr (5). HITACHI CD ROM DRIVES (Exdem.) ETHERNET CARD Internal bus CDR and half height. 3600 3500 5 25 inch with card and cable L259 (car,. (5). Novell compatible 16 bit L99 (carr C2(. Internal embedded SCSI CD413650. half height. 5 25 inch (259 (carr. (5). External cased AT bus CDR1502S. half height. 5.25 inch with card and cable (299 (cart. ES). POWER SUPPLIES Aster BM 140 IBM XT/AT compatible 150W; 5V at 15A. -12V at 5A, -5V at 0.3A, -12V at 0.5A: fan cooled. rear DISK DRIVE CONTROLLER CARDS panel switch, good value at (19 50 lcar E4) XT MFM (37.50, XT RLL (37.50. AT RLL (37.50, AT MFM (49.95, AT IDE £19.50 (Can C2.50). Farnell N180 R113U 100W; 5V at 40A, ' 12V at 5A, 24V at 5A, -5V at 1A. (26.95(car, (3). VIDEO COLOUR PRINTER IBM COMPATIBLE MOTHERBOARDS, CARDS etc. Hitachi VV25E PAL video printer. Produces high density photographic quality colour prints in A6 size from PAL 25MHz 486 Very latest 80486 motherboard with extra 64K cache. Landmark speed approx 100MHz. video (TV) source 0299 (car, (12). Floating point Co-processor built into CPU. Eight expansion slots. SAE for full details. (1295 leer, (5). NB VAT and carriage must be added to all items (quotes for carriage overseas) Everything new. and guaranteed 6 months unless stated Access and Visa telephone service Visa & Access Matmos Ltd. has been trading successfully since 1976. VISA phone service MATMOS LTD, UNIT 11 THE ENTERPRISE PARK, LEWES ROAD, LINDFIELD, potmos WEST SUSSEX RH16 2LX. 0444 482091 and 0444 483830 (Fax 0444 484258) SEE OUR OTHER ADVERTISEMENT ON PAGE 343

INDEX TO ADVERTISERS

PAGE PAGE PAGE Airlink Transformers 268 G H Systems 314 MQP Electronics 316

American Automation Halcyon Electronics 349 Mutek - 266 UK 344 Hoka Electronics 278 Number One Systems 299 Audio Electronics 289 ICOM UK 293 Panrix Electronics 349 Bamber Electronics 278 Integrex 271 Phase Track 357 Blackmore 268 IPK 309 R Henson 316

Blue Chip Technology . 319 IR Group 274 Ralfe Electronics 290 Brain Boxes 306 J & M Computers 310 Raedek Electronics 314 Bull Electrical 333 James Brice Associates 314 Sherwood Data Systems Camel Services 306 Johns Radio 310 309 Capella Technos 303 Kestrel Electronic Smart Communications 290 Chelmer Valve Components 293 Stewart of Reading 319 Company 285 Keytronics 350 System Request 344 Citadel Products IFC Labcentre 309 Taylor Bros (Oldham) IBC Colomore Electronics 303 Laplace 306 Those Engineers 303 Dataman Design OBC Lowe Electrical 268 Thurlby Thandar .. 289,316 Design Consultancy.... 359 M&B Electrical 276 Triangle Digital Services Display Electronics .... 343 M&B Radio 319 278 E.A. Sowter 310 Matmos 360 Tsien (UK) 294 Ellmax Electronics ...... 285 Micro Processor First Rental 273 Engineering 344

OVERSEAS ADVERTISEMENT AGENTS France and Belgium: Pierre Mussard, 18-20 Place de la Madeleine, Paris 75008. United States of America: Jay Fenman. Reed Business Ltd., 205 East 42nd Street, New York, NY 10017 - Telephone 1212) 867 2080 - Telex 23827.

Printed in Great Britain by Riverside Press. Gillingham, Kent. and typeset by Marlin Graphics, Sidcup. Kent D \14 5DT, for the proprietors, Reed Business Publishing Ltd, Quadrant House, The Quadrant, Sutton, Surrey SM2 SAS. © Retd Publishing Ltd 1991. Flectrnnlcs and Wireless World can be obtained from the following: AUSTRALIA and NEW ZEALAND: Gordon & Crotch Ltd, INDIA: A.H. Wheeler & Co, CANADA: The Wm Rawson Subscription Service l,td., Gordon & notch Ltd., SOUTll AFRICA: Central News Agency Ltd.; William Dawson & Sons IS.A.I Ltd.: UNITED STATES: Worldwide \ edia Services Inc., I IS East 23rd Street. NEW YORK, N.Y. 101110. USA. Electronics & Wireless World $5.95 1745131.

3(11) ELECTRON I('S \VORLD+W I RECESS \\ ORLD April 1991 TAYLOR

P30 RANGE STEREO FM RADIO (88-11oMHz) MODULATORS TRANSMITTERS & TRANSPOSERS

P30 902P BAND 2 FM STEREO MODULATOR.

19" Rack Mounting Zit 35)mm deep Any specified fnatuency .88-110)111x. Crystal controlled IF-RF 1-equency stability < 5ppm Temp controlled VCO, frequency stability t 2.5KHz Audio input .7V .000 Balanced (Isolating transformer) XLR Sockets Audio bandwidth 401íz-ISKHz TAYLOR Pre -e mphasis 50ís & 75µs Crosstalk <40,1B 1KHz L&R volume controls with 2 analogue level meters L'1 Devi..lion level control wits analogue deviation meter I KHz tone generator svvitd able L or R. L & R. 4So+ta 902-P IF Loop on front panel Volta>;e 220-240V AC 5011: (110-120V AC no cost option F) Output level 63dimV(15011mV) 750 (IEC Connector) OPTION G 500 no cost (V Connector)

OPTION A Output Level I Watt 500 E190.00

OPTION B Output Frequency 420-460 MHz /900.920 MHz Specify Frequency E 80.00 £540.00

P30 -30VF 30WATT BAND 2 POWER AMP WITH AGC

19" Rack Mounting 2µ 425mm deep Gain 30dB +20dB AGC. Enables power amplifier to be sited remote from modulator linked by atax cable with attenuation up to 20dB.

Input Impedance 750. (IEC Connector) Output Power 20 Watts into 5011(N Connector) f Voltage 220-240V \C 50Hz (110-120V no cost option F) £901.00 e P-30 P30 30VFT 30 WATT BAND 2 TRANSPOSER WITH AGC;

Power: Specification as PJO JOVE Input: 88-110MIk/420-460MHz/ 900-920MHz 500 (N Connector) Specify Frequency

Crystal Controlled Frequency Stability <5ppm Gain 93 dB AGC 40dI1(t 20dB). £1261.00 '

P30 -300VF 300 WATT BAND 2 POWER AMP WITH AGC ,

19" Radt Mounting 40 500mm deep Gain 42dB +20dB AGC. Enables power amplifier to be sited remote from modulator linked by coax cable with attenuation up to 20dB.

Input Impedance 7511. (IEC connector) Output Power 300 Watts into 5011(N Connector) £2668.00 Voltage 220-240V AC 501 z (110-120V no cost option F)

P30 -300V FT 300 WATT AND 2 TRANSPOSER WITH 'AGC

Power: Specification as P30-300VF Input: 88.110MHz1420-460MhIz/ 900-920MHz 500 (N Connector) Specify Frequency

Crystal Controlled Frequency Stability <5ppm Gain 103dB AGC 44,18 022dB). £2928.00

ALL PRICES EXC VAT & EX -WORKS Taylor Bros.(Oldham) Limited. TeI:061 652 3221, Tlx: 669911, Fax: 061 626 1736 CIRCLE NO. í020N REPLY CARD Dataman Introduces Omni -Pro at £395

S3 as a Programmer... SDE S3 will program virtually any EPROM or Assembler £195 EEPROM that will go in the socket. Without recharging, you can program I (XX) modern fast Develop your New Product in PROMS or 10(1 ancient slow PROMS. Operation is continuous with a mains supply: S3 can be an advanced Software Develop- used while recharging. S3 does not monopolise ment Environment. your computer for copying. editing or programming PROMS. S3 uses latest high-speed Dataman's SDE comprises a ©` programming methods and supports FI.ASII EI'ROMS. Program, Data and Configuration are two -window Editor, fast Macro c. O 1004'© retained while turned -off S3 has a ROM BIOS, Assembler, Linker, Librarian, Serial but runs its main program in RAM. Software can Comms and an intelligent Make facility be upgraded instantly from a PROM in the which automatically reassembles o socket. SOFTWARE UPGRADES ARE FREE. ONLY those files you have edited, links them What you get with S3... and downloads to your Mains Charger. Ring -Bound FactoFile Memory -Emulator or Programmer. Manual. Emulation Lead (plugs into your ROM SDE works very well with S3. socket). Write -lead (hooks -up your uP Write u hen -Line emulating RAM in a ROM The Editor is pretty smart: it can tell you the socket), FREE Software Upgrades by BBS. Absolute - . Address of any line of the Source -File. S3 -The-Best-Seller £495 Technical Support by Phone. Fax and BBS and a The Assembler is pretty smart too: if it finds a FULL TI IREE EAR l GUARANTEE. mistake it puts you hack in the Editor at the right Wouldn't you like an EPROM place to fix it. SDE's Multi -Processor version supports all common micros - please ask for list. Programmer that is Elegant? The Disassember version creates Source Files Stunning? Superb? from Object Code (e.g. from a ROM). SDE IS NOT COPY -PROTECTED. These are words used by engineers to SDE Multi -processors & Disassemblers £695 SDE Multi -processors describe S3. They often say S3 makes £395 SDE Single -processor £ 195 their expensive lab -programmer look stupid. Flow can we disagree? When designing S3 we tried to turn a boring Strobe Eraser £175 bench -instrument into something more exciting: a compact..intelligenl tool Wipes EPROMS before you which could be used for New Product can say "Jack Development. with facilities such as Robinson". Editing and Memory -Emulation. We Our Flashy New Eraser wipes EPROMS made S3 small enough to slip in a pocket clean in seconds. You can do it to chips and battery Omni-Pro -powered so that it would £395 on the bench, chips in -circuit or even retain data and configuration, because chips in the Programmer. Tidy up your we were sure engineers would want one Programs BIPOLARS, workshop tomorrow. Recycle all those each. And they do! S3 is now the PROMS, PALS, GALS, old Memory Chips! hest -selling programmer in the U.K. EPLDS, PEELS, IFLS, S3 is likely to fill needs that you never EPROMS, EEPROMS knew you had! We can send you an S3 AND MICROCONTROLLERS. =t today on FREE TRIAL - 30 DAYS Tests SRAM, DRAM SALE -OR -RETURN. AND TTL/CMOS logic Optional S3 Modules... Omni -Pro uses a short slot PC card to EPLDS. CMOS PALS £295 32 pin EPROMS £75 make fast parallel transfers of data. It is 40 pin EPROMS £75 controlled by software with a 8748/49 £ 125 professional look and feel. The latest 8751/53 £ 125 XICOR 2212 quick -programming methods are UK customers please add VAT £45 supported. Any of the usual Optional S3 Developers Package file -transmission formats can he used. AMERICAN Software and Inside Information for engineers Omni -Pro is compatible with all popular VIM EXRESS ( who wish to study and customise S3. \o I'LD compilers producing JEDEC files. Secrets! Editor/Assembler (SDE see below). Circuit Diagrams. I.ist of Calls and BIOS Source Omni -Pro comes with this Universal Code £195 Guarantee: it WILL program all the S3 as a Development System... parts you need. Or you can have your altaman The FREE Terminal Program which comes with money hack. S3 provides Full Remote Control from your PC. Station Road, Maiden Newton, All keyboard functions are - supported such as What you get with Omni -Pro... Dorset DT2 OAE, Editing. Byte and Block Shifting. Split & England An Excellent Manual in Plain English. A Phone 0300-20719 Shuffle. Seek and CheckSum. S3 is also a quality 40pin TEXTOOI. Double -Width Socket, Memory - Fax 0300-21012 Emulator it will substitute ROM or FREE Technical Support by Phone. Fax or BBS, RAM in -circuit. You can try your Telex 418442 program FREE Software Upgrades by BITS and a FULL. before committing it to PROM. YEAR'S GUARANTEE. BBS (Bulletin Board) ... 030(121095 300/1200/2400/N,8,1 (24hr) CIRCLE NO. 103 ON REPLY CARD