March 1978 International

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ew Communications Section- for Hams, SWL's and CB'ers RN I

MARCH 1978 INTERNATIONAL

NZ S1.50 ',LJHF FREQUENCY i COUNTER PROJECT 1

Computerised Musical 1 Doorbell Project:

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Audio enthusiasts the world over Outstanding among the amplifier RS-9900US. have come to expect exciting unit's many features is the fixed innovations from Technics. The plus variable calibration controls Two compone is RS-9900US is one of them. Unlike for equalisation lines, and Dolby* for one reason: other cassette decks it is a `cassette record and playback levels. Com- system'-the separation of the plete with peak reading meters of To outperform sensitive amplifier electronics studio standards, Dolby'` noise from the mechanical tape transport reduction circuitry and a built-in all other to obtain optimum performance 400Hz/ kHz test oscillator for cassette decks. from each. level calibration -and head Features in the transport unit azimuth adjustments. include a closed loop, double - An evaluatioft ¿if the Technics capstan, 3 -motor drive to provide RS-9900US capabilities will pro- smooth tape travel and closest vide the answer to any contradic- tape-to -head contact; pitch con- tions about cassette equipment trol of ±5% and full IC logic performance. all transport functions control of 'Under licence from Dolby Laboratories Inc. to ensure tape safety when . switching modes. The true 3 -head system permits professional -type tape/ source monitoring. ra Technics h. -f. WARRANT< For a National Technics Catalogue, please write to: T78.17 ®wicó National Technics Advisory Service, P.O. Box 49, Kensington, N.S.W. 2033. AUSTRALIAN OWNED AND PRODUCED March 1978. Vol, 8 No. 3.

electronics 1 INTERNATIONAL

Editorial: Les Bell

Publisher: Collyn Rivers PROJECTS

136: Linear Scale Capacitance Meter Useful test instrument 11 714: VHF Log -Periodic Antenna Baluns, splitters, etc. ....33 588: Theatrical Lighting Controller Final details 47 639: Musical Doorbell Australian design! 58 140: 1 GHz Frequency Meter / Timer High-performance test gear 85

New ComnWxctrone Sectron- lot Mens.sWlf and CB*, r Ls FEATURES r ,. >

.tAl1CN rar.r-- Sound.. -'"-SÑr[RMArg/IAl Looks at the 17 a1ae latest Hi-Fi UHF FREOUENCY COUNTER PROJECT Pirated Recordings Detection of counterfeits 27 Computerised Musical Doorbell Project. Inside Information from Ultrasound 41 Ultrasonics assists diagnosis

Print Out New devices, boards, systems 52 Digital Electronics by Experiment 73 Practical 'teach -yourself' series

Noting Down Music by Computer 79 UNBMI Computer transcribes performances

Self -resonance in Capacitors 80 Important in RF applications NEWS & INFORMATION News Digest 5 PCB's for Sound projects 92 Briefs 21 Calculator Offer Necklace 95 Offer 24 Communications A Modern Magazines Print News .... 100 Publication Out News 52 Ideas for Recomended retail price only. Door Bell Experimenters ... 107 Offer 63 Reader Services Mini Mart 114 66 Index to Advertisers 114 Registered for posting as a publication - Data Sheet Category B 67

ELECTRONICS TODAY INTERNATIONAL - MARCH 1978 3 A 4N 11.14).%

Puzzlea tvi ameters? Spaced/ byl specs? Or just plan confused about the who field?

p ed is the answer! It's a complete up-to-the-minute guide to understanding hi-fi written in good plain non- 1>` technical English.

Here's all you need to know kki, to choose the right equipment for your own special needs. How to get it right first time!

A Modern Magazines v\I.' Publication

Rushcutters Bay. NSW 2011 from Hi -Fi Review 15-19 Boundary St, ..vailab1e from most newsagents or directly Pr;ce $3.40 (incl. postage & packing).

MARCH 1978 ELECTRONICS TODAY INTERNATIONAL - 4 News Digest

Lauber - I Microphone Sennheiser has now released a new, extremely small lavalier microphone with a frequency response of 50- I I , 20,000 Hz. Identified as the MKE 10, it is an omni-directional electret condenser microphone, and has flat frequency response characteristics and low sensiti- 0 vity to vibrational pick up. For outdoor 771 work it is fitted with built-in pop filter and windscreen, and an additional windscreen is available for severe conditions.

Experiment in Theatre for Television. preparation. It has Armstrong applications similar Audio/Video Pty Limited to the present range, but due to its has constructed a temporary television dimensions it may be used as a centre handheld at the Open Stage Theatre in or pocket unit. Outside Melbourne dimensions are to house one million dollars' 119.1 x 93.6 x 30.0 mm. worth of technical equipment used for Two water-resistant boxes have also the production of playwright Ray been introduced. Features are as follows: Lawler's "Doll" trilogy. Metric Taptite screws recessed into, the The television centre a contains video lid of the box to a control provide flat top room, lighting control room and surface. An earth dimmer board. connection facility is provided inside the box. Neoprene All of the videotape equipment in sealing ring. the video control Corrosion Resistant to room was supplied by Industrial and Marine Ampex Australia Pty. Ltd, environments. including Good surface. Finished stove enamelled, three VPR-1 broadcast quality video- medium hammer Grey. Readily tape recorders and this is the first time machined. Robust and rugged. Diecast these recorders have been used in a in Aluminium Alloy to BS1490 LM6. major television production in Australia. Outside dimensions are: Model 9732P Up to three cameras were 1 isolated - 125 x 80 x 45mm; Model 9920P to each of the - Ampex VPR-1 recorders 220 x 120 x 66mm. If used with equipment which lacks to give the producers a powering a greater flexibility Further information from R.H. facility, battery adaptor, when editing the final model MZA 10, is product. The Cunningham Pty. Ltd., Melbourne 329- available. three plays, "Kid Stakes", "Other 329-9633 and all states. Further details from Australian Times" and "Summer of the Seven- distributors R.H. Cunningham Pty. Ltd. teenth Doll" were produced by the Wireless Video Game (in your phone book). Melbourne Theatre Company and A new IC being developed by Intermetall Armstrong Audio/Video for the Seven GmbH, the West German division of LCD Projector Network, and will be ready for ITT Semiconductors, is designed to Liquid crystals seem to be finding their transmission by late February. operate with that company's ultrasonic way into all kinds of devices these days, or infrared remote New Eddystone boxes control chips. The the latest being a large screen multi- SAA1080 is designed to be built into colour Two additions have been made to the projection system for tactical the TV set, and will play up to tem displays, now being established range of Eddystone diecast evaluated by the boxes. games in colour. US Navy. The projector, which was developed by Hughes Aircraft, utilises The model 9830P offers the Flat Colour CRT a single liquid crystal light valve to advantages of volume with the mini- RCA's David Sarnoff Research Centre, provide 1,500 lumens on a 10 mum of height. Like the others, a ft square it has at Princeton, New Jersey, are developing close fitting flanged lid, screen. Reliability, often claimed to be a secured by four a 76 x 100 cm colour TV display about countersunk screws. problem with LCDs, seems quite good - 50 mm thick. The device uses electron MTBF The box is of the device is 5,000 hours, and supplied unfinished, but multipliers to create the free electrons, a prototype has operated reliably for surface will accept any finish, which are then accelerated to strike the 1,100 hours over a 17 month period including cellulose, with a minimum of phosphor screen. with no degradation or failure.

ELECTRONICS TODAY INTERNATIONAL - FEBRUARY 1978 5 News Digest TM 500 Oscilloscope Plug -In Tektronix, Inc. have added a new oscilloscope plug-in to the TM 500 family of modular test and measure- SC SO4 80MHz OSCILLOSCOPE ment instruments. The 80 MHz, dual - sum trace SC 504 combines with a selection counters and other 4- of pulse generators, i TM 500 instruments to form versatile instrument configurations for measurements on digital equipment - all in one - --+-- , - 7 convenient package. In addition to ! , I -1 a compact packaging, this configuration r f t ,1_ I+ offers a rear panel interface for inter- connecting the various instruments. control, the SC 504 an With a front panel q1 can, for instance, be switched from dis- . playing external signals to displaying the .r. dt waveform input to its companion Nár counter or the output from the pulse d generator. 1CM1-9-CMi!( *POSITION P. capabilities of r 1 vsuNM ti Specific performance POI II the SC 504 Oscilloscope include 5 mV/ div sensitivity at 80 MHz; calibrated sweep rates to 5 ns/div; a selection of channel 1, channel 2, alternate, chopped, o l°¡¡w'" o channel 1 + channel 2, channel 1 - channel 2, and x -y display modes, z-axis input; and high writing speed. Auto, normal, and single -sweep trigger AC, AC low L*.__. modes; a selection of frequency reject, AC high frequency Victorian Test reject, and DC trigger coupling; and a Novice Licence - question to help all actual and are also allowed to keep the choice of channel 1, channel 2, line, In order an invaluable aid in prospective candidates for the Novice papers, this forms external, or interface (TM 500 back - the Youth Radio pinpointing weaknesses and con- plane) trigger sources provide great Amateur Licence, time. (Victorian Division) will sequently optimising study operational flexibility. Clubs Scheme a week of Novice Examination on Results will be posted within Further information from Tektronix hold a Trial Novice Exam is un- April 15, 1978. The place of the exam. The Trial Australia Pty. Ltd., 80 Waterloo Rd., Saturday the best possible single examination will be near the central questionably North Ryde, 2113. preparation -for the Novice area of Melbourne and will be easily form of Examination. accessible by public transport. Parking Licence Please help us by applying as soon as will be available. fee is $1.00 (this is pass rate in the Official Exam possible. The exam The cover costs, the YRCS Analog -Digital Conversion Notes: has in the past beenlow, and the Trial E used to partially profits), and should be sent The first major updating of Analog Exam is intended to improve the degree makes no as a postal note or Devices' highly successful Analog -Digital preparation of candidates for the with your application of made out to the Youth Radio Conversion Handbook (1972) not only actual exam papers. A similar Trial a cheque Clubs Scheme; please DON'T send cash. gives a new look at basic understanding Exam was held in 1977; amongst the but sat for The fee should be included with a note and application of data conversion, Trial Exam candidates who then two new chapters address- Exam, the pass rate was containing your: also includes the May Novice ing the contemporary challenges of twice the average Novice initials approkímately Surname and monolithic IC converter designs and complete pass rate! Many of these Postal address (in full, including and that they would interfacing with microprocessors candidates commented postcode) computers. Considerable coverage is not have passed the official exam if they Telephone number (if none, current designs, the trial exam. also given to had not first sat for write "nil") technologies, and production techniques Comments were also made on the circuits, decreased nerves Applications should be posted to: employed in conversion beneficial effect of (A) thin-film-on-CMOS, .where this is a including (especially in Morse laser -wafer -trimming, I2L, and hybrids. and (B) specific YRCS Trial Novice Exam, 11 Vista significant factor), is aimed at the engineer or many questions types. Avenue, Kew, Vic. 3101. The book preparation for scientist who now uses or is likely to use A great deal of effort and time converters ín his work. (including time) has gone into It is important that applications are computer (ISBN: 0-916550-03-6). Write: ensuring that the Trial Exam will be as prompt, as there are a limited number very Parameters Pty. Ltd., P.O. Box 480, similar as possible in all respects to the of places which are expected to fill quickly. Replies containing all other Crows Nest, NSW, 2065. Please include material and organisation of the Official $10.00 which includes answer sheets will be details of the exam will be posted one cheque for Exam. Candidates' packing and posting. returned when marked; since candidates to two weeks before the exam.

t ELECTRONICS TODAY INTERNATIONAL - MARCH 1978 6 Random Access Vídeo Using the freeze-frame, if the U-Matic is so Video-Dex 2010 U-Matic equipped. Vegas Consumer Electronics Show, users while can now select instantaneously The Timex have lowered all their any spot required for In Video-Dex does not interfere prices with presentation. with the normal their cheapest model at addition, the presentation begins on the functions of the U-Matic $24.95. On the machine. Demonstrations sidelines, both Fairchild first frame without the need of Video-Dex and National for old- can be arranged by Semiconductor are looking fashioned countdown. Both of these contacting at moving back up in the market to factors Professional Video Services on (02) 290 more are vital 3359. expensive models with increased for television stations, value. advertising agencies, universities or Tape Chip anyone needing a precise and pro- A new IC from National, the Dimmer fessional LM1818, Sensor presentation. combines all the electronics required siemens has build to introduced a new MOS IC a tape deck except the bias which can replace rotary potentiometers oscillator. The chip carries two used in light dimmer switches. By touch- preamplifiers for record and playback, ing a sensor surface it is automatic possible to vary level control circuitry, meter the brightness of light bulbs and also to 10Ep-CEx drive, and most importantly, record/ switch them on and off. playback switching. 15 transistors are A PMOS depletion -type IC, used to S 566 B, create a more flexible and has been used.to design a dimmer switch reliable switching circuit than the without mechanical parts. mechanical There is types previously used. ample room for the circuitry in Samples are conven- being shipped now, with tional switch boxes and there is no need production sceduled for June, at a US for wiring modifications. price around the dollar mark in volume. To switch a lamp on or off the sensor must be touched 12 -Bit A/D Converter briefly for about 60 series ms to 400 ms. A series When a lamp is switched of integrated circuit 12 -bit on, the last analog-to selected brightness level is -digital converters, which restored. To includes the make the lamp brighter or industry's first A/D dimmer, the sensor must be converter to guarantee no touched for missing code longer than 400 ms without operation over the full -55°C to interr- +125°C uption. If this is repeated, the military/aerospace temperature range, direction has been introduced by the Micro- electronics Division of Analog Devices. The new AD572 is packaged in an all - me tal, hermetically -sealed, electrostatic- ally and electromagnetically shielded dual -in-line package, and is available in "A", "B", and "S" versions offering a range of temperature operation and Professional Video Services Pty. of Ltd. performance characteristics for both r17"7"r"'" 35-43 Clarence Street, Sydney, has industrial announced afid military/aerospace the release in Australia of requirements. the Video-Dex 2010 random access For further information A controller for U-Matic contact videocassette Bruce McCarthy, Parameters Pty. Ltd., machines. The Video-Dex 2010 keeps ' accurate P.O. Box 480, Crows Nest, NSW, 2065 track of tape location by - Phone 439-3288. generating storing and displaying precise r numerical addresses for every point on the tape - with one second accuracy. This results in reduced search time and operator error. A presenter can select any part of a i,. videocassette to show. Once the selection has been placed in the Video-Dex, the 'rj __ _ . presenter need not touch thé U-Matíc machine, as the Video-Dex will of brightness control is out search ...&0512c reversed. The that particular programme or ell time taken to go through the entire programme segment and bring it up on brightness range from dark the to bright monitor and can even stop after the back to dark is about 7 seconds. presentation if so programmed. Any number of mechanical switches The U-Matic videocassette or sensors (consisting of a transistor and machine Watch Battle three can even be in a different room since all resistors) can be connected to a The U.S. digital watch market is the presenter needs is the Video-Dex still in special input of the 8 -pin MOS IC which 2010 turmoil as Timex and Texas Instruments is mounted in a dual control panel. All functions of the lock in -line package. U-Matic horns. The latest round of price For further can be controlled from the carbs information please Video-Dex has seen TI introduce LCD models contact Siemens Industries control panel including at the $15 mark, Limited, unveiled at the Las Melbourne, Sydney, Brisbane and Perth.

ELECTRONICS TODAY INTERNATIONAL - MARCH 1978 7 THE LOUDSPEAKER WITH ATOUGH ACT TO FOLLOW: JBL's NEW L40.

Every sound is clean and clear. Listen For the past 21/2 years, weve been to the snap of a rimshot. the crash of a making a two-way bookshelf loudspeaker cymbal. Pure. Accurate. Perfectly defined. called the L26. The critics loved it. The you'd like the technical information on loved it. The customers loved it. (If dealers write us and we'll send you an 250,000 times to be exact. the L40. engineering staff report. Nothing fancy The smart thing to do would've been except the specs.) to just keep cranking out those L26's for 1°'"1WWWWWWWWW Go listen to the L4O. And ask for it by the next hundred years. Never change a its first name: JBL. You'll be getting the " winner, right? Not if you're JBL. same craftsmanship, the same compo- Meet JBL's brand new L4O. nents, the same sound heard. in the very the best two-way loudspeakers studios in the world. It's one of top recording the number of Top Fifty albums Here's why: about getting Ranked by you can buy. If you've been thinking they produced last year. seven of the ten lead- fidelity, we used IBL to power han- into high performance high ing recording studios in the world The L4O has tremendous new L40. or mix their music.They used our fool you. know a great place to start: JBL's record dling capability. Don't let its size lot sound to make theirs. It's a whole lot of JBL for not a whole It'll play right up there with loudspeakers Source: Recording Institute of'America. of money. twice its size.

Dinnb, ed by Road, BROOKVALE, N SW 2100. Telephone 939 2922. HARMAN AUSTRALIA PTY. LTD., 271 Harbord JBL

GET ITALL. News Digest

ETI/Unitrex Calculator Contest In the January issue we ..1 left our man in PNG held captive by a lying and a truthful guard in a hut with two doors, only one of which leads to freedom. He was allowed one question to help trim decide which exit to take. No doubt about it, if Shane Martin of Barraba, NSW was caught in that situation, he would escape easily. Shane wins this month's calculator for his answer: he would ask `Which door would the other guard say is the door freedom?', and then exit by the opposite door -to the one the guard indicates. Our propagation expert, of course, being a propagation expert, calmly waited for a magnetic equatorial Sporadic -E opening, whereupon he whipped out his cunningly concealed 6 metre transceiver and made contact with a station in East Timor who relayed his message to Darwin, who relayed.... Anyway, to cut a long story short, now Telecom Approved Recorder ATDA Urges Comsat System Shane has worked out the answer for us Telecom has sanctioned the use of a The Australian we can radio it back to our man, thus modified Telecommunications version of a "National" Development Association securing his release. I don't know, cassette has come out recorder, designated model No: in support of a national communications though, maybe we should let him stew RQ 413 SP for use as an attachment to satellite system for for a while.... record Australia to augment telephone conversations. The existing. communications K. Wallace of Nord's Wharf, NSW asks: modifications systems. to the standard This is contained in a A cup of coffee and a cup of tea, "National" submission by both recorder comply with Tele- the association to the Australian of equal volume, are placed on a table. com specifications, and A installation Government Task Force which is teaspoon of coffee ís put into the tea- must be carried out by Telecom cup and tech- inquiring into all aspects of a national stirred thoroughly. Then a tea- nicians. This involves the fitting of a satellite system. spoon of the mixture from the teacup signal box in the is put telephone circuit, into The association has stressed in its back into the coffee cup. Does which the recorder is It the coffee plugged. will submission that if the decision to go now have more tea in it than record phone conversations at the tea has the press ahead with a satellite system was made a coffee, or vice versa? of a button, and may Seal also be used as a large proportion of it must be developed an empty envelope, write your conventional cassette unit, to replay and built in Australia. answer on the back of it, with your standard tapes name of conversations or music. "The establishment of a and address, and send it to: Unitrex Thus it can national double as a dictating communications satellite provides the Calculator Contest (March), ETI machine and a playback Magazine, 15 unit for inform- opportunity to build up our industry by Boundary St, Rushcutters ation gathered on Bay, NSW tape by people in the allowing us to be involved to 2011. The closing date is 21st field. the maximum possible extent" the April. Application for installation must be submission states. "This must not be made on Telecom form TS72, which another major project going to Errata sets overseas out the conditions under which it sources. The Australian tele- In the December issue 8080 Octal may be operated. The recommended communications industry was estab- Monitor Program, a section of code was retail price of the unit ready for install- lished to provide communications unfortunately omitted from page 95, ation is $170.00 plus a Telecom services for this country from local between locations 234 and 250 of the installation charge to around $25.00 manufacture. second page. It is reproduced here with The unit is available now from "Australia's future for manufacturing apologies to the many frustrated National dealers in all States. lies in the areas of high technology." programmers who are out there, and thanks to the chap who brought it to our attention. 235 346 003 Digital Speech and ANI 3 MASI( OFF ALL Interpolation only allocating them a satellite 237 366 260 BUT 3 BITS ORI 260 FORM ASCII DIGIT 241 315 362 377 CALL PNT Research into telephone channel when there is a PRINT FIRST OCTAL 01011 conversations speech signal 244 175 MCP/ A L MOVE L TO ACCUMULATOR has 245017 RRC revealed that of any group of present. The equipment ROTATE RIGHT 3 TIMES incorporates 246 017 RRC speakers, only about one third are five Texas Instruments TMS9900 16 -bit 247 017 RRC actually talking at one time. New equip- microprocessors. The engineers who We were rather out of date with the ment being installed at ground stations designed the system seem to have decided addresses of the WIA divisional offices as part of the International Time Division that the obvious alternative of asking given in the January issue. The correct Multiple Access satellite communication callers not to pause for breath would addresses are as follows: VIC 412 system - uses this principle to save satellite not meet with widespread public Brunswick St, Fitzroy 3065; TAS - P.O. channels by monitoring telephone lines approval! Box 1010, Launceston 7250; and ACT - P.O. Box 46, Canberra City 2601.

ELECTRONICS TODAY INTERNATIONAL MARCH 1978 - 9 DIRECTSL DRIVE-7D TURNTABLE DENON SPECIFICATIONS providing a direct drive system with the following features:- STARTING TIME: 2.1 seconds for 0 to 33-1/3 r.p.m.

HIGH ROTATIONAL ACCURACY WOW AND FLUTTER: LARGE DIAMETER TURNTABLE Less than 0.04% (WRMS) at 33-1/3 r.p.m. , - EQUIPPED WITH STROBOSCOPE & FELT INSULATORS RUBBER RATIO: INDEPENDENT CUEING LEVER SIGNAL TO NOISE HIGH SENSITIVITY TONE ARM Over 60 dB. WOW AND FLUTTER OF LESS POWER CONSUMPTION: THAN 0.04 PER CENT (WRMS) at 12 watts DENS 33-1/3 rpm The Professional Audio Brand .n:umr loot Iron DENON .. ,. SA -3900 AMPLIFIER

l.rbl. pmrr This integrated stereo unit has a rated output of 40W I. I. + 40W both channels driven, and through the use of PNP- NPN transistors a pure complementary circuit has been Residual Noise: Lower than 2 mV (0.5µW) SPECIFICATIONS in driver Factor: More than 35 provided, permitting improvement All silicon transistor stereo premain Damping efficiency and power bandwidth. amplifier. Power Bandwidth: 20 Hz - 45 kHz (-3 dB at rated output)

ST -3900 DENSN,..w...... P.

) rlrilr 11,,,, U l,,l,ll,l,lrr:l, Tuner rlrlr lllll',7,rl:,i,rrIli,lloÍ 14 -FM 102 MiI EX, OM id AM qe qM Mil aM 90 92 I4a aMa aD ar. . I. Mt OM IIM WWI gU The design of this receiver has been co-ordinated with that of the above integrated amplifier, p.-^ and features include silicon IC chip, diode limiter, and three V ceramic filter elements. Also provided is a muting circuit to minimise Interstation noise.

11111 SPECIFICATIONS Hi -Fi Audio Equipment WIRELESS (AUSTRALASIA) LIMITED Solid State AM -FM Stereo AMALGAMATED Road, Ashfield, NSW 2131 Phone 797 5757 Tuner. 554 Parramatta 3 -Integrated Circuit, 1-FET, Melbourne Brisbane Adelaide Perth Hobart Townsville Canberra 8 -Transistor and 5 -Diode. 560 4533 44 1631 272 2366 71 0888 34 5266 79 6155 95 3431 Power Requirement: AC 100, 120, 200, 220 Newcastle Launceston 2 5166 44 5155 230-240 volts changeable, AD A18 50/60 Hz

INTERNATIONAL MARCH 1978 10 ELECTRONICS TODAY - Project 136

AM\ OM - e u it --nee If you want to find out what values those odd capacitors are, then here's the instrument for you.

ONE OF THE HANDIEST instruments for an electronics hobbyist, or to have around an electronics workshop, is a capacitance meter. Every multimeter has a resistance scale - and it gets used quite often. But there is often a requirement for measuring capacitance, and few multimeters have a capacitance range. For example, measuring the value of a variable capacitor used to temporarily Alt* 'trim' a filter or oscillator that is to be replaced by a set of fixed capacitors. $4. Or a bagful of 'bargain' unmarked s / capacitors may have been obtained or - the color code or numeral code has disappeared and the value of a y cow as x component needs to be c x determined. por, Once you have a capacitance meter, , you suddenly find uses for it! This capacitance meter provides a linear scale readout of the value of unknown capacitors generally to within 5% or as good as 2% depending on the 41 accuracy of the meter used.

Range The meter will measure caoacitance values down to 5 pF and up to 1 µF. Scale divisions on the model shown were at 2.5% intervals. All the range resistors, R7 Five ranges are provided: 100 to R11, value is required then standard 5% or pF, and 1 R12 are high tolerance 1% 10% nF, 10 nF, 100 nF and 1 µF. or 2% tolerance resistors may be used, resistors accurately measured Different ranges can be provided by to be obviating the need for selecting them, or within the tolerance selecting different values for the range required. If only buying the expensive high tolerance 5% or 10% accuracy of resistors R7 to R11. For example, five capacitance types. ranges from 47 pF to 0.47 ;IF could be included by changing R7 to 470 ohms, R8 to 4.7k etc. The meter scale would have to be hand -calibrated in this case. SPECIFICATION - ETI 136 Construction Capacitance ranges 100 pF, 1 nF, 1 The construction is quite straight- 10 nF, 100 nF, µF. Accuracy 5% or better forward. The majority of the small (2% components are mounted on the printed possible with component selection) Calibration by internal circuit board. The range resistors are calibration capacitor Power requirements 240 V AC or 2 x 9V No. mo}pnted on the switch lugs as illustrated 916 batteries in the photographs.

ELECTRONICS TODAY INTERNATIONAL - MARCH 1978 11 Project 136

The printed circuit board, meter, Little difficulty should be exper- Note: A suitable edge meter is available range switch, potentiometers, pilot light ienced if the component overlay is from Ham Radio Suppliers 323 measurement terminals and on/off followed and the photographs are Elizabeth St, Melbourne 3000 switch are all mounted on the front referred to during construction. (67-7329, 67-4286). They have been as panel illustrated. Note that alternative panel layout is advertised at $3.00 each (plus P & P The power supply is mounted on the possible if a standard type of panel if ordered by mail). The particular back panel, as is the mains/battery meter is used rather than the edgewise meters are 0-1 mA movements switch. The batteries (if used) may be meter shown in the photographs. calibrated 0-5 ounces. The scale is mounted inside the case. Overall case The front panel was hand -lettered easily removed and reversed to size is 180 mm wide by 95 mm deep by with Letraset on the prototype. A provide a blank scale which can be 128 mm high. Scotchcal type front panel could also be hand -calibrated (use a reg. voltage A small tagstrip is used to terminate prepared if desired. supply a good pot. and a mirror the mains input and transformer leads The CAL. potentiometer is a screw- scale or digital meter to set the and the rectifier components. Both the . driver -adjust type and was mounted current points). This is best done back panel and the front panel should with a fixing collet. Knob-twiddlers with the meter mounted on the be connected to the mains earth which can cause havoc. panel. Excellent accuracy can be is terminated on the tagstrip, the strip's obtained. . earth tag being secured under one of the Using the Meter transformer mounting bolts. Once the instrument has been tested The calibration capacitor is a high and confirmed to be in working order, tolerance (2% or better) polystyrene switch the range switch to the 100 pF or, better still a silver mica type. This position and turn the SET ZERO PARTS LIST - ETI 136 control i component is mounted from the so that the meter reads zero with no Resistors appropriate switch lug to a suitable capacitor connected to the Cx terminals. R1 560k ,'4W ground lug mounted on the front panel. Then switch to the CAL. position and R2 470 ohm. '4W The printed circuit board has PC adjust the CAL. poténtiometer so that R3, 6, 13 1k5. '4W stakes (or pins) soldered in all the the meter reads full scale. R5 10k, '4W R7 1k,'%W.2% positions marked on the component Now you are set to measure all those R8 10k, " " either use 2% tol. overlay. . 'unknown' capacitors. R9 100k " " resistors or selec- Two of these (marked E and Cx on Any devices used to grip capacitors ted 5% or 10% the PC artwork) are used to mount the being measured, and plugged into the tol. see text. PCB directly on the back of the R10, 12 1M " " "Cx" Cx terminals, will add stray capacitance R11 10M " " terminals, as illustrated in the photo- and this will need to be compensated RV1 10k/A panel mounted, screw- graphs. This avoids increasing the for by readjusting the zero set control. driver adjusted circuit stray capacitance. RV2 500 ohm/A pot. Continued on page 14 .. . Capacitors Cl 3n3, Philips polystyrene or silver mica C2 10n F greencap or ceramic C3 1n Philips polystyrene (selected, 2%) or silver mica, 2% C4 100n greencap C5 100n F greencap C6 640 uF, 25V electrolytic Semiconductors D1 EM401 or similar S1 DPST or DPDT, 250 V AC rated min. toggle switch S2 SPOT or %-DPDT min, toggle switch S3 single pole, six -position OAK switch 01 2N2646 02 BC107 or BC108, BC109 or equivalent ICI LM555 or NE555 timer IC. PI IC2 78L12 (preferred) or 7812 or LM340-T12 Miscellaneous Jo' T1 PF2851 or M2851, 12.6 V C.T. @ 150 mA

i, Pilot 12 V, 20 mA bayonet lamp and holder. Case Instrument case, Australian Transistor Co. model 754 or similar M1 0-1 mA meter, see text Sundries pk screws, wire, batteries, nuts, bolts, tagstrip, etc.

12 ELECTRONICS TODAY INTERNATIONAL - MARCH 1978 Project 136

111 ------r

If you want to find out what values those odd capacitors are, then here's the instrument for you.

ONE OF THE HANDIEST instruments for an electronics hobbyist, or to have around an electronics workshop, is a capacitance meter. Every multimeter has a resistance scale - and it gets used quite often. But there is often a requirement for measuring capacitance, and few multimeters have a capacitance range. For example, measuring the value of of 0° a variable capacitor used to temporarily 0114 'trim' a filter or oscillator that is to be u"pf 7 replaced by a set of fixed capacitors. u,. -f Or a bagful of 'bargain' unmarked é capacitors may have been obtained or the color code or numeral code has 1 °:* o-é disappeared and the value of a C 100i. component needs to be determined. v of Once you have a capacitance meter, you suddenly find uses for it! This capacitance meter provides a linear scale readout of the value of unknown capacitors generally to within 5% or as good as 2% depending on the rTrn}e accuracy of the meter used.

Range The meter will measure capacitance

values down to 5 pF and up to 1 µF. Scale divisions on the model shown were at 2.5% intervals. All the range resistors, R7 to R11, value is required then standard 5% or Five ranges are provided: 100 pF, and R12 are high tolerance 1% or 2% 10% tolerance resistors may be used, 1 nF, 10 nF, 100 nF and 1 µF. resistors accurately measured, to be obviating the need for selecting them, Different ranges can be by or provided within the tolerance required. If only buying the selecting different values for expensive high tolerance the range 5% or 10% accuracy of capacitance types. resistors R7 to R11. For example, five ranges from 47 pF to 0.47 µF could be included by changing R7 to 470 ohms, R8 to 4.7k etc. The meter scale would have to be hand -calibrated in this case. SPECIFICATION - ETI 136 Construction Capacitance ranges 100 pF, 1 nF, 10 nF, 100 nF, 1 µF. The construction is quite straight- Accuracy 5% or better forward. The majority of the small (2% possible with component selection) components are mounted on the printed Calibration by internal calibration capacitor circuit board. The range resistors are Power requirements 240 V AC or 2 x 9V No. 916 batteries mounted on the switch lugs as illustrated ín the photographs.

ELECTRONICS TODAY INTERNATIONAL - MARCH 1978 11 Project 136

The printed circuit board, meter, Little difficulty should be exper- Note: A suitable edge meter is available range switch, potentiometers, pilot light ienced if the component overlay is from Ham Radio Suppliers 323 measurement terminals and on/off followed and the photographs are Elizabeth St, Melbourne 3000 switch are all mounted on the front referred to during construction. (67-7329, 67-4286). They have been panel as illustrated. Note that alternative panel layout is advertised at $3.00 each (plus P & P The power supply is mounted on the possible if a standard type of panel if ordered by mail). The particular back panel, as is the mains/battery meter is used rather than the edgewise meters are 0-1 mA movements switch. The batteries (if used) may be meter shown in the photographs. calibrated 0-5 ounces. The scale is mounted inside the case. Overall case The front panel was hand -lettered easily removed and reversed to size is 180 mm wide by 95 mm deep by with Letraset on the prototype. A provide a blank scale which can be 128 mm high. Scotchcal type front panel could also be hand -calibrated (use a reg. voltage A small tagstrip is used to terminate prepared if desired. supply a good pot. and a mirror the mains input and transformer leads The CAL. potentiometer is a screw- scale or digital meter to set the and the rectifier components. Both the . driver -adjust type and was mounted current points). This is best done back panel and the front panel should with a fixing collet. Knob-twiddlers with the meter mounted on the be connected to the mains earth which can cause havoc. panel. Excellent accuracy can be is terminated on the tagstrip, the strip's obtained. . earth tag being secured under one of the Using the Meter transformer mounting bolts. Once the instrument has been tested The calibration capacitor is a high and confirmed to be in working order, tolerance (2% or better) polystyrene switch the range switch to the 100 pF or, better still a silver mica type. This position and turn the SET ZERO control PARTS LIST - ETI 136 i component is mounted from the so zero that the meter reads with no Resistors appropriate switch lug to a suitable capacitor connected to the Cx terminals. R1 560k,'/.W ground lug mounted,on the front panel. Then switch to the CAL. position and R2 470 ohm. '/. W The printed circuit board has PC adjust the CAL. potentiometer so that R3, 6, 13 1k5. %VV R5 10k, '4W stakes (or pins) soldered in all the the meter reads scale. full R7 1k, %W. 2% positions marked on the component Now you are set to measure all those R8 10k, " " either use 2%tol. overlay. . 'unknown' capacitors. R9 100k " " resistors or selec- Two of these (marked E and Cx on Any devices used to grip capacitors ted 5% or 10% tol. see text. the PC artwork) are used to mount the being measured, and plugged the into R10, 12 1M " " PCB directly on the back of the "Cx" Cx terminals, will add stray capacitance R11 10M " " terminals, as illustrated in the photo- and this will need to be compensated RV 1 10k/A panel mounted, screw- graphs. This avoids increasing the for by readjusting the zero set control. driver adjusted RV2 circuit stray capacitance. 500 ohm/A pot. Continued on page 14 .. . Capacitors Cl 3n3, Philips polystyrene or silver mica C2 10nF greencap or ceramic C3 1n Philips polystyrene (selected, 2%) or silver mica, 2% C4 100nF greencap C5 100n F greencap C6 640 uF, 25V electrolytic Semiconductors D1 EM401 or similar S1 DPST or DPDT, 250 V AC rated min. toggle switch S2 SPDT or %-DPDT min, toggle switch S3 single pole, six -position OAK switch e Q1 2N2646 Q2 BC107 or BC108, BC109 or equivalent ICI LM555 or NE555 timer IC. IC2 78L12 (preferred) or 7812 or LM340-T12

Miscellaneous T1 PF2851 or M2851, 12.6 V C.T. @ 150 mA Pilot 12 V, 20 mA bayonet lamp y and holder. Case Instrument case, Australian Transistor Co. model 754 or similar M1 0-1 mA meter, see text Sundries pk screws, wire, batteries, nuts, bolts, tagstrip, etc.

12 ELECTRONICS TODAY INTERNATIONAL - MARCH 1978 BAIT. OUT

Cd MAINS 100n T 1 1I 2, 9V Na 916 BATTERIES

+ C6 125V640y D1 1I EM401 12.6V CT R4 150mA 120R T1 I PF 2851

R13 1k5

18 Si 2N2648 01 - IC7 - NE555 (OIL)

NOTES: 0-1mA R7 ARE %W. 1% OR 78L12 RV2 -R12 2% EDGEWISE METER RESISTORS OR SELECTED 500R 02 BC107.8,9 7812 OR OTHER 5% RESISTORS. ALL OTHER - IC2 78L12 or SET me. - LM340-T12 SUITABLE TYPE RESISTORS LW, 10%. 7812 or ZERO LM340-T12 Cl. C3 ARE POLYSTYRENE e OR SILVER MICA. IN 000OUT IN OUT REF. REF.

BLACK E TERMINAL

1 Cx 4 . 2 w {,!5 a, V R7 -R12 and C3 are mounted on the rear of the range switch C 1 RED _ TERMINAL - att 113 XII IT1 W N } > Om Jt- N H> +

INSERT P.C. STAKE IN HOLES MARKED THUS.

HOW IT WORKS - ETI 136

A unijunction transistor, Q1, is connected When ICI receives a trigger pulse at pin the relaxation oscillator frequency and as a relaxation oscillator with a frequency 2, the flip-flop is set, releasing the short trigger pulse duration. determined by R1 -C1. The frequency of circuit across Cx and driving the output, The current measured through the oscillation in this instance is about 1 kHz. pin 3, high. The voltage across the 'load' resistor on the output (R6) of IC1 Pulses of about 1 µ s duration are capacitor then increases exponentially for will thus be directly proportional to the produced across R4 each time the UJT a period that depends on the value of the value of the unknown capacitor Cx. "fires". The resistance between b2 and bl unknown capacitance Cx. The period is The meter, M1, measures the current of the UJT reduces to a low value each determined according to the formula: through R6, the meter inertia 'averaging' time the emitter conducts. Much of the the current. t = 1.1 RrCx charge stored in Cl is "dumped" across As the voltage at the output pin swings R4 for the short duration that the c-bl At the end of the period, the compar- between about 2/3 Vcc and less than 1/3 junction of Q1 conducts. ator resets the flip-flop which in turn Vcc in its 'high' and 'low' states respectively The narrow pulses across R4 drive the discharges the unknown capacitor, Cx, and the DC offset is compensated for by base of Q2 via R3, which serves as a drives the output to its low state. returning the 'load' current through an base -current limiting resistor. The pulses This cycle .is repeated each time a offset voltage developed across VR2 via cause Q2 to conduct for the same duration, negative -going trigger pulse appears at pin R13 from the supply rail. that is, about 1 µ 5, and negative -going 2ofICI. Zero -setting is accomplished by making pulses from the collector of Q2 drive the Thus as the range resistor value (Rr) VR2 variable. A calibration control is "TRIGGER" input of the 555 timer, is fixed, the ON/OFF ratio of the output provided by making a portion of the IC1. This is connected to operate as a voltage will be determined by the value of 'load' resistance variable - VR1 here. monostable in this circuit. Cx. The ON/OFF ratio is independent of

ELECTRONICS TODAY INTERNATIONAL - MARCH 1978 13 Project 136 ... from oage 12 However, this will only have to be done readout. Thirdly, the edge meter used in the construction. on the 100 pF and 1000 pF ranges as little panel space, giving it a clean, A calibration position is provided on the added capacitance will be negligible uncluttered appearance. the range switch for the sake of conven- on the higher ranges. A 0-1 mA meter was used as it has a ience. The original model did not have convenient scale. If you use a range with this refinement but we soon added it Meters full-scale values of 47 pF to 0.47 µF a when we found out how useful it was! it An edgewise -mounted panel meter was 500 µA FSD meter will have to be used. also helps to maintain accuracy as a used in the prototype for several The zero -set potentiometer, VR2, 'standard' capacitor does not have to be reasons. Firstly, we had one! Secondly, provides a small voltage offset as the kept external to the instrument for this a scale nearly 50 cm long allowed us to output, pin 3, or IC1 does not go to purpose - we kept losing ours until we calibrate the meter at very close intervals zero volts and it also compensates for put it in the circuit! - 2.5% here, and still give accurate the effect of the small stray capacitance

CAL CAPACITANCE METER SET ZERO PANEL LETTERING O 0

Cx + 1000pF 0.01µF

0 0 100pF 0.1{1F

CAL. 1µF o OFF o ON PILOT RANGE

175 r

12. 25

NOTES:

O 4 HOLES, 10mm DIA.

(3 1 HOLE, 8mm DIA. w 0 2 HOLES, 8mm DIA. FRONT PANEL SECURED BY FOUR SMALL SELF - ID 4 HOLES, 2mm DIA. TAPPERS. BACK PANEL SECURED IN SIMILAR ALL DIMENSIONS ARE IN MANNER. MILLIMETERS. PROTOTYPE PANEL LAYOUT

14 ELECTRONICS TODAY INTERNATIONAL - MARCH 1978 3009 SerieslIl 1 now more than ever... ,,r:.- The best pick-up arm ín the world

Unique balance system to give moulded carbon fibre and nitrogen - Tracking force of 2.5g with 0-1.5g fine

minimum -inertia operation for cartridges hardened titanium, achieving a rigidity adjustment and 1 g of coarse adjustment. weighing anything from 1 2g down to many times that of aluminium or other Longitudinal and lateral balance with zero. conventional materials, and providing a fine adjustment. Ingenious construction, with high - natural loss of unwanted acoustic Fluid -damped lowering and raising density metal cores in precision plastic information. control.

mouldings. Viscous damping in both planes, with Output : twin gold-plated phono Conventional tone -arm and shell are choice of three damping rates covering sockets plus separate ground. replaced by an integral carrying arm all cartridge compliances. For further information, write to which is interchangeable for multi - Bias graduated from 0 to 2.5g with AUDIO ENGINEERS PTY. LTD. cartridge use. Carrying arm is formed of fine adjustment.

AUDIO ENGINEERS P/L AUDIO ENGINEERS (Vic.) AUDIO ENGINEERS (Old.) ATHOL M. HILL P/L 342 Kent Street. 2A Hill Street. 5IACastlemaine Street. 33 Wittenoom Street. SYDNEY 2000 N.S.W. THORNBURY 3071 Vic. MILTON 4064 Old. EAST PERTH 6000 W.A. AE127/FP 1 1

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Est ^ orroton3 - ow TIP/ ON SUMPS.

Ortofon professional cutter head type DSS 732 in Latest from Ortofon is the M 20 Super-a unique action. magnetic stereo cartridge, based on our exclusive world -patented Variable Magnetic Shunt (VMS) principle. When it comes to perfection in recorded sound the principle is as simple as this: What goes in must come out. Which means that the response from the groove of your favourite record should be as close as possible to the sound of the original master tape. With this in mind, we at Ortofon concentrate our activities in two areas only: the production of sophisticated cutting equipment for making master records-and the manufacture of the finest pick-up cartridges to play the discs which they produce. Most of the major record companies use Ortofon cutters. And because it is only natural.that the manufacturer who knows most about making the records should also know most about playing them, our cartridges for many years have been the choice of professionals and discerning music lovers throughout the world. Ortofon do not make turntables, amplifiers or loudspeakers. We put all our experience into developing advanced products to cover the two most critical sectors in sound reproduction: the cutting and the playback of records. For us accuracy in sound is more than just a slogan. It's our reason for being in business. orrofon D.stnbuted by- accuracy in sound HARMAN AUSTRALIA PTY. LTD.. Dbtnnuted m New Zealand by- P O Box 6. BROOKVALE. N S. W. 2100. AWA NEW ZEALAND Ltd P.O. Box 1363, AUCKLAND, Telephone: 76 0129; Telephone: (02) 939 2922 WELLINGTON, Telephone: 85 1279; CHRISTCHURCH, Telephone: 89 0449. Arm/Cartridge Interface (it's actually grey hammer finish but we'll let that pass) based It seems obvious that most of the new crop of moving -coil on a first stage buffer amp interfacing with the cartridge, cartridges are capable of delivering very fine performance a precise RIAA equalisation stage, and then a further buffer when correctly fitted to a suitable arm. The interesting thing amplifier which feeds direct to the line -level inputs of the here is that the ultra -low mass syndrome is no longer prevalent majority of preamps. (The aux. input will normally be used). and that manufacturers of both arms and cartridges have come Used with the 'black box', the 20B sounds vastly improved, to grips with the idea that a moving -coil cartridge, by virtue of giving a very detailed and beautifully balanced result. One its low compliance, needs at least a medium mass arm (say 15 thing in favour of the 20B is its first class tracking perfor- gm or so effective mass less cartridge) to avoid serious mance, which has made it a cartridge well worth considering in resonance problems in the low frequency band. The mass will any event. obviously have a stabilising effect on the pickup system Modular Electronics can also supply equalisation cards enabling the stylus to follow the groove modulations without suitable for the Decca 6E (at last!) and the next subject for the entire pickup system attempting to trace very low treatment is the Garrott P77, which we wouldn't have thought frequencies. Our own experiments so far indicate that arms needed much doing to it to judge from our experience. The such as the Formula 4, whilst providing first class conditions P77, fitted with a Weinz stylus, a parabolic type from W. for high -compliance cartridges, do give low -frequency problems Germany, looks like being a big favourite and if its performance with items like the Denon DL103, the Ortofon MC20 and bur can be even further improved using the Modular Electronics regular Decca 6E. unit, a lot of listeners will be very happy indeed. The 'black Of course, low effective mass is most needed in the vertical box' can be ordered direct from Modular Electronics and plane to avoid loss of contact between stylús and groove on expected RRP is $149. warped and rippled record surfaced, whilst stability (by virtue of mass) is most needed in the lateral plane, since bass modul- Jordan -Watts Flagon ations on records are almost invariably lateral with minimal The Jordan -Watts Flagon loudspeaker, using a single Jordan - vertical elements. One solution to th'e conflicting demands of Watts drive unit module (we shall describe this in greater is low vertical mass and high horizontal mass the excellent detail in the next issue) is based on a ceramic enclosure which Dynavector (Onlife) arm which must currently take the cake looks like a traditional wine flagon. The drive -unit, a full -range is a for innovative and practical design. This arm based on device with a metal diaphragm, is sealed into the enclosure and massive pedestal which also enables it to be used free-standing covered at the front with a rather garish grille made of wooden (i.e. not secured to the turntable) and the main carrying arm, strips glued to a gauze backing. A lead -out cable is provided also very massive, pivots only in the horizontal plane. This for input connection. main arm supports an offset sub arm which, whilst of adequate Continued overleaf rigidity and total mass relative to its size, has very low effective vertical mass. The sub arm, which carries the headshell and, beyond its pivot (which allows only vertical motion) a very small counterweight, is unlikely to allow series resonances to v develop in the audible band. The only possible penalties arising from the use of the short sub arm are, first, that greater distortion due to vertical tracking angle changes is likely by comparison with arms having longer effective length in the vertical plane - although this is probably of less consequence than the mistracking distortion resulting from a high -mass arm playing a warped record; and secondly, the pivots for the sub arm must be very carefully made and maintained, for friction so close to the stylus would obviously have greater influence than the same amount of friction in a longer arm. So far, we've heard a Dynavector 20B in this unusual looking arm and can only confirm that the cartridge gives a distinct performance improvement thus 'used. After our initial, rather disappointing acquaintance with the 20B, as used in JH and SME arms, we were, of course, agreeably surprised. But it doesn't end there. Read on for more news on the 20B.

Cartridge/Amplifier Interface The 20B has displayed certain problems with the majority of preamps, resulting in noticeable bass -shyness and a rather prominent high treble brightness. These effects are due to modification of the 20B's frequency response by reactive components in the equalisation section of the preamp. To overcome this problem, Modular Electronics, P.O. Box 245, Narrabeen, NSW, 2101, has introd9ced a 'black box'

ELECTRONICS TODAY INTERNATIONAL - MARCH 1978 17 einTTf n _n tiÁ.1JP11"11 A, The inside of the enclosure appears to be stuffed with foam found the sound very satisfying indeed, with a dramatic plastic, and the cork stopper is hollow in the middle to provide impression of perspective and wide dynamics, first class reflex loading. The speaker system combines a number of definition, extremely stable .stereo imaging and good important desiderata - a non -resonant enclosure material, for coherency of complex sounds. example, of irregular shape. Most people refuse to take the Well, we can live with the colouration which was by no Flagons seriously, which is a pity since for size they sound means unpleasant, for the other qualities of the samples illus- exceptionally good,'the main drawback being a lack of genuine trated very clearly the benefits of a really good single -diaphragm bass output (which one would expect anyway from a compact full range drive unit. We're sure we haven't heard the last of loudspeaker) and a deep nasal colouration giving certain male Jordan -Watts and look forward to hearing others in the range speakers the effect that they have mild sinusitis. Even so, we - samples are to hand but as yet we've not had the opportunity to set them up. Spectrum Planning Plea

INCREASING PUBLIC DEMAND for high quality stereo FM radio broadcasts is underlining the appalling state of frequency allocation in Australia. In a situation where a major television channel has been allocated a frequency hardly suitablé for TV transmissions (channel 0); where TV transmissions occuPy part of the spectrum used overseas for FM radio; where communications for air traffic control use frequencies different to those employed internationally (thus necessitating duplicate radio equipment for aircraft flying into Australia from overseas), it is clear that effective long term planning is overdue. Even though some of the decisions contributing to this woeful situation could, under prevailing circumstances, have been justified at the times they were made, other decisions - such as the UHF/FM radio idea, mooted by major industrial interests and fortunately scotched before UHF sound broadcasting was forced upon us - have definitely been against the public interest and are now causing enormous problems to the authorities and broadcasting licensees involved. This is the view of Grahame Wilson, spokesperson for the Public Broad- r casting Association of Australia. Mr. Wilson discussed the situation with us at some length and pointed out that, with the Geneva World Administrative Radio Conference taking place in 1979, an enquuiry into radio frequency spectrum management in Australia was immediately necessary for the formulation of future broadcasting policy. The enquiry should: - review the demands for radio services - review recent technical developments which might alter the use of the radio spectrum - recommend long term policies on radio spectrum use - show how long and short.term use of the radio spectrum -.. .. - , - can be balanced - declare what research could help make better use of the radio spectrum - consider the implications of the International Tele- communications Union's policy - consider the immediate needs of Australian radio broadcasters and - determine the role in spectrum planning of the Post and Telecommunications Department. Mr. Wilson believes such an enquiry, resulting in concrete proposals and actions for sorting out Australia's broadcasting mess, could save Australia from the sort of problem referred to by McLean in his 1975 report - 'The non-standard use in i 1-i A Australia of the Band 88 108 MHz has given rise a large - to -r- I párt of the problem on which we have been called in to make

18 ELECTRONICS TODAY INTERNATIONAL - MARCH 1978 recommendations. The introduction of FM (sound broadcast- In a press release drawn up for the Public Broadcasting anomalies ing) into the UHF band would also be contrary to international Association of Australia, Mr. Wilson attributes these of television practice and could consequently give rise to similar embarrass- to the need for quick, high powered penetration development in ment in the future'. services. The cost is now being felt with the behind the rest of the The result of the McLean report was introduction of Australia of FM radio some 25 years experimental broadcasts in Sydney, Melbourne and Brisbane, world. later giving way in Sydney to a full stereo service on 92.1 MHz by 2MBS-FM. Timetable The extreme difficulty being experienced in allocating FM Mr. Wilson. It is Political Plaything services now needs to be emphasised, says a timetable for overall frequency spectrum We asked Mr. Wilson whether yet another enquiry into broad- time for definite be drawn up. The effect of changing casting was likely to return any successful result, and he management reform to in FM band will be felt by all UHF informed us that this particular enquiry was essential to avoid frequency allocations the not television services. The embarrassment for Australia at the 1979 WAR conference. and VHF spectrum users, only managed, provide ample space The main problem seemed to be that no rigid policy for future radio spectrum, if properly will 40 FM services in the 88 108 MHz planning was currently available and this was the real cause (Washington DC has over - and the for concern. Mr Wilson pointed out that broadcasting as a band!) for everyone; broadcasters, communicators general public. There should be clear separation between user whole was really a political plaything, with very few people allocating authority. The latter should be seeming to realise the tremendous importance of proper bodies and the at the entire radio spectrum, with clear management and planning. He urged the introduction, as soon charged with looking instructions for forward planning and evaluation of competing as practicable, of UHF TV broadcasting, ideal for Australian analysis. conditions where terrain and community virtually dictated uses on the basis of cost/benefit Had this been carried out in the 1950's and 1960's it is use of local broadcasting stations rather than fewer VHF might not have gone directly to UHF TV as a stations covering wide service areas. And with a large number possible we to our needs, as was done in the UK for the intro- of domestic TV receivers now equipped with UHF tuners, such solution duction of colour television - no VHF colour telecasts were a changeover would seem to be a logical move, especially in made and VHF monochrome receivers are no longer available, regions where existing VHF services (channels 3, 4 and 5) simultaneous VHF mono broadcasts gradually being overlapped internationally used FM sound broadcast frequen- the phased out. Thus the present difficulties caused by our non- cies. use the VHF band might never have occurred. This particular problem arose from a request in 1961 to standard of the time to introduce increase the number of VHF TV channels from 10 to 13, and Mr. Wilson emphasised that was now, for the situation, left to the com- in response to this the Huxley Committee recommended planning policies of a direct departures fróm the ITU (International Telecommuni- promise now being advocated to enable establishment of new FM radio cations Union) preferred usages of spectrum space. small number (up to seven in Sydney) anything Other TV channels cause other problems. Channel 5A was stations, would certainly not improve. Apart from use of the radio placed in an international satellite and space research band, else, concrete proposals for more efficient embarrassment at currently still in use. Part of Channel 0 falls into the amateur spectrum would save Australia from acute nothing of the improve- radio band (50 - 54 MHz) preferred for ITU region 3, which the 1979 WAR conference - to say for the community includes Australia. This particular channel is technically barely ment and increase of all broadcast services suitable for TV broadcasting! Another unusual feature of the as a whole. can be Australian allocation is the existence of a space, 6/7ths of a Further details and background information Association Aust- TV channel wide, left between channels 9 and 10 for use by obtained from the Public Broadcasting of domestic aviation. ralia, P.O. Box 578, North Sydney, NSW 2060. SHORE OCTAVE ANALYSER

frequency TO HI -Fl ENTHUSIASTS, Shure Brothers of the USA is best feedback filter system or octave equaliser, the known for its range of pickup cartridges and its association frequency response of a public address or sound reproducing give useful with the specialist British pickup -arm maker, SME. facility within it. Whilst the system has potential to setting, our But in the recording and broadcasting field, Shure is known measurements of a hi-fi system in a domestic us believe that mainly for its microphones and other products aimed at the experience with this and other systems leads to situation professional user. a compensated frequency response in such a listening There Among the electronic components produced by the does not always give improved subjective performance. here, and one of these is the company is an equalisation analysis system, consisting basically are several possible explanations living room on audio frequencies of a 'black box' model M615, fitted with a random noise influence of the ordinary for the severely undulating generator for use as a signal source, the unit also being due to its small size. Compensating in rooms is the chief problem, particular- provided with a LED indicator system for measuring relative bass response smaller response varies dramatically ín different parts of the level in each of ten octave bands. Auxiliary to this unit is model ly since wide -response hi-fi systems will be ES615 analyser microphone, featuring a response tailored room - as listeners of feasibly be improved, actually specifically for use with the M615. aware. Thus a response might listening area but can easily The purpose of the system is to analyse the overall frequency and subjectively, for a very small elsewhere. response of an auditorium and to optimise, using an anti - degrade performance 19 ELECTRONICS TODAY INTERNATIONAL - MARCH 1978

t , iS

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MAIL ORDERS EIIUSTRORICS AVAILABLE TOO 289 LATROBE ST, MELBOURNE. Ph (03) 663 1785 There's no doubt the system is very effective indeed. We were able to equalise our hi-fi system in less than three or four minutes after a little practice, and that involved treatment of Regardless of the problems of performing subjectively each stereo channel individually. acceptable equalisation, and the foregoing is not to say that The equipment was a joy to use - including Shure's SR107 PA equalisation is necessarily a simple process, Shure appears equaliser whose rotary controls were, to us, easier to operate to have done everything possible to ensure rapid and effective than the slider normally found on such equipment. Sliders, use of graphic - or more correctly, octave - equalisers in a in our view, are only useful in applications where several sound system. We received samples of the complete equalisation controls are likely to be manipulated at the same time and analyser, complete with microphone and all accessories, neatly where instant indication of their position is necessary. Mixing and safely contained in a tough lightweight suitcase type desk faders are the obvious application. carrying case. We also received Shure's SR107 mono octave We won't go into great details of the equipment. Excellent equaliser which had been sent for assessment by Hi -Fi Review descriptive material is available from Shure. We will say that magazine. it is extremely flexible and is usefully provided with both XLR Different operating procedures are employed for P.A. work and standard tip -and -sleeve jack connectors for interface with and hi-fi system analysis. But the fundamental procedure is the just about any installation. same. Basically the idea is to equalise the system using an No doubt more accurate equalisationwould be available octave equaliser while reducing the range of the 'hi -lo' using a third -octave system but this would obviously be more envelope, this being defined by the appropriate rotary control complex, both in design and operation. Shure's octave system on the analyser front panel, and indication of response peaks provides a very effective and economical answer to the or dips using the LED indicators. By reducing the size of the problem it solves and its portability offers great convenience. envelope by degrees, it is possible to identify very rapidly We can imagine any number of useful possibilities for the where response deviations occur and to take appropriate system and anyone who is professionally involved in sound action with the octave equaliser. reproduction should at least check it out. SOUND BRIEFS

Meridian Designed by Lecson originators Alan Boothroyd and Bob Stuart, the Meridian range consists of an amplifier based on `black box' type units with minimal controls. A loudspeaker system has also been introduced.

Audio Technica Completely new Audio Technica ranges, including cartridges and headphones, are in production and should soon be freely available.

Decca International Arm Latest Decca problem to be solved is incorrect lateral balance of most production samples. Solution involves enlarging the headshell plug grubscrew hole at the front end of the aluminium tube to a slot enabling the headshell to be twisted to give correct alignment.

Garrard Impulse NR Unit Presumably based on bucket -brigade electronic time delay circuitry similar to that used in the SAE 5000 impulse noise reduction unit, Garrard's new box of tricks has been released in the U.K. and should soon be available here.

Headshells Coral, the Japanese speaker people, have introduced a complex alloy `special metal' headshell of tremendous rigidity. Though fairly massive, the sample we've received from Garrott Bros. in Melbourne seems to give improved performance especially with moving -coil cartridges.

Sub Woofers With JR, Chartwell, JBL and Phase Linear (amongst others) all introducing sub - woofer systems recently, either as part of complete stereo speaker systems or as separate add-on units, it will be interesting to discover whether centre bass affects stereo performance and whether the interference effects of conventional pairs of full -range woofers might be more tolerable.

More Speaker Trends Seems probably that more and more speakers will be equipped with active crossovers and integral power amplifiers before long. The Boothroyd-Stuart Meridian, the JBL L212 and several other new designs are either fully or partly self powered.

Linn Isobarik Speakers Although we've indicated that Lin Isobarik speakers might soon be available in Aust- ralia, the likelihood is now remote. The reason, we understand, is high cost of the speakers themselves in addition to the three Naim 250 power amps, active crossover and preamp needed. With a Linn-Sondek turntable, this little system costs more than £4,000 in the U.K. which, with tariffs, tax and so forth would bring the local price to a minimum of $10,000!

ELECTRONICS TODAY INTERNATIONAL - MARCH 1978 21 Modern expertise and computer technology have created a fine piece of equipment. The NEW

. o, ---+ . 0

/li/

a Y, . * .I' DM7 is the f`yst o I new loudspe; r 15mily edir> our computer -aided research grogr iárnealth mpac 3 u'nit,system_empíoying entirely ew drive units in a endíosure engineered to exceptionálly -high andards. Many advances have -been incorporated to reveal new hdrizons in loudspeaker'performance, making possible a standard of musical reproduction unequalled tin an enclosure of this size. The DM7 gives almost perfect amplitude linearity __throughout the entire audio spectrum, and produces phase -coherent sound within a The DM7 complements a broad listening area. Thedrive units are purpose -designed range monitor and manufactured entirely in our own factory, employ- remarkable of ing new technology in order to achieve incredibly low loudspeakers from B & W. distortion levels - typically less than 1% THD from 30Hz to 200Hz and less than 0.5% above that frequency. Another new feature in the DM7 is a variable energy Britain's first control giving four frequency weightings - different to loudspeakers . A dyn.m lc system r ph.see nt those obtainable from the control unit to accommo- acct willaccu ruw - y achieved Only by thie very best electrostatic designs. date widely varying room acoustics. Hear the B & W DM7 - you may well agree that this is The OMa is. 3 unit monitor the finest small speaker in the world today. Guaranteed loudspeaker system th.t produces high quality results from an for 5 years. Incredibly smell cabinet (20.8 litr.sl making It perfect for horn. or small studio use where space es at a minimum. Only 28" it 9" a 95". 1, Despite Its compact size, NSW: CONVOY SOUND WOOLLOOMOOLOO SHOWROOM 357 2444; INSTROL HI-FI DM5 speakers can be rated 26 2798 MILVERSON PTY.LTD. as a system of wry high PTY.LTD. 29 7290; PARK ST. HI-FI STEREO CENTRE Quality. The design (CHATSWOOD) 412 2122 (PARRAMATTA) 635 35881 RIVEhINA HI-FI 938 2663/4; phllnsphy of John Bowers UNITED RADIO DISTRIBUTORS PTY.LTD. 232 3718; ARROW ELECTRONICS 29 8580; To design loudspeakers RUSSIN HI-FI 799 2421; PITMAN'S RADIO & TV (WAGGA) 25 21551 ALBURY AUDIO thet reproduce in your CENTRE 25 1712; LEISURE SOUND (CHATSWOOD) 411 4944; WROTH CENTRE HI-FI borne sound its you wuld (BATHURST) 31 2088; BYRON BAY TV 6 SOUND CENTRE 85 6762t SINGLETON hear in the concert hell" HIGH FIDELITY CONSULTANTS 72 2270; HIFl JUNCTION 389 4000; ACT: DURA TONE 82 1388; VIC: SHEPPARTON HI-FI 21 9006; ENCEL ELECTRONICS PTY.LTD. 42 3761: SOUND SPECTRUM (GEELONG) 96616;SOUTHERN SOUND (CITY) 677869 _9 (MOORABBIN) 97 7245; TIVOLI HI-FI 81 2872; THE SOUND CRAFTSMAN 509 2444; Buy RITE ELECTRI%426200; NATSOUND 678158; INSTROL HI-FI 675831; INSTROL HI-FI (FRANKSTON) 783 7535; OLD. JOHN GIPPS SOUND 360080; PREMIER SOUND (NTH. ROCKHAMPTON) 27 4004; TARGA ELECTRONICS (CAIRNS) 53 2715; RUSS ADAM (TOWNSV ILLE) 71 5618; TAS. BEL CANTO (HOBART) 34 2006; UNITED ELEC TRONICS (LAUNCESTON) 318528; AUDIO SERVICES (BURNIE) 312390; WEST. AUST. TECHNICAL SERVICES PTY.LTD. 31 5455; THE GINZA 61 7444; STH. AUST. BLACK - WOOD SOUND CENTRE 278 1281:INSTROL HI-FI 2237622; SOUND SPECTRUM 2232181.

Sole Australian agent: Coll_ f.- 4 Dowling Street, Sydney 2001. Phone: 358 2088. IDNTERNATIONAL ItSirk.

Now, professional Motor System. The steadi- 3 -head monitoring est, most accurate tape - transport method. Speed in a cassette deck. accuracy is superb, with Up to now you had to Wow and Flutter below choose between a cassette Y 0.08% (WRMS). deck for convenience. Or, To adapt the Model 5030 reel-to-reel for profes- to any of the three most sional recording features. popular tape formulations, Now have it both ways in press one of the three but- the Marantz 5030 cassette tons marked "Tape EQ and deck. BIAS:' There are settings Here's how: for standard Ferric -Oxide, The Marantz 5030 has Chromium Dioxide (Cr02) separate record and play- or Ferri -Chrome (FeCr) back heads... the same as tape. reel-to-reel. This gives you With Mic/Line Mixing, an instant check of the two sources can be re- quality of your recording corded at the same time, as you record. And, like some of the most expen- combining line and microphone inputs. The sive reel-to-reel decks, the record and playback Master Gain Control lets you increase or de- heads on the Model 5030 are super -hard perm- crease the overall volume of the total mix. alloy-a long-lasting metal alloy that gives What else could we pack into a front load better frequency response and signal to noise cassette deck? ratio than Ferrite material. More features. Like a 3 -digit tape counter For precise azimuth alignment, both the with memory function. Viscous Damped Verti- playback/monitoring and record heads are cal -load Cassette Door. Switchable Peak Limiter. set side -by -side within a single metal en- Fast -response LED Peak Indicators. 3" Extended - closure. They can't go 'out of tracking range Professional VU Meters. Locking Pause alignment. Control for momentary shut-off in record or Complementing this outstanding "head - play ... and Total Shut-off in all modes when technology" is Full -Process Dolby* Noise Reduc- the tape ends. tion Circuitry. It not only functions during And, of course, the unbeatable Marantz 5030 record and playback ... but during monitoring is front loading. Easy to stack or fit on a shelf. as well. The styling is clean and bold. The sound is the What drives the tape past the heads is every truest recreation of what was put on tape. If you bit as important as the heads themselves. For want the best-then do what you really want to this reason the Model 5030 has a DC -Servo do-go for it. Go for Marantz.

We sound better. Distributed by Auriema (Australasia) Pty. Limited (A subsidiary of Superscope Inc. of the U.S.A.) - P.O. Box 604, Brookvale. N.S.W. 2100. *TM Dolby Labs, Inc. © 1978 Marantz Co., Inc., a subsidiary of Superscope, Inc., 20525 Nordhoff St., Chatsworth, CA 91311. Prices and models subject to change without notice. Consult the Yellow Pages for your nearest Marantz dealer. 4TDK netic X49.95

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TDK NECKLACE OFFER

Please forward one TDK Magnetic Necklace. I enclose my cheque/postal note for $49.95 accordingly. Please make cheques etc. payable to 'Necklace Offer' and post together with order form (or replica thereof) to 'Necklace Offer' Electronics Today International, 15 Boundary St, Rushcutters Bay, NSW, 2011. Name

Address

Postcode Please specify your choice

0 Gold-plated, designed for women L Rhodium -plated, designed for men J Neckl

VERY many people suffer from so-called 'stiff Necklaces should be ordered via this magazine using shoulders' or 'stiff necks'. It is generally believed that the form (or replica thereof) published on this page. these unpleasant symptoms are caused by mental or Please make cheques payable to 'Necklace offer' and bodily stress but the exact cause is not apparently really send Cl- Hi -Fi Review, 15 Boundary St, Rushcutters Bay known. NSW, 2011. The TDK Electronics Corporation have produced a Please allow at least three to four weeks for delivery magnetic necklace which they state has proven effective - there really are mail delays - particularly of parcels! in relieving such symptoms for a very high proportion of Thousands of people have used these necklaces and sufferers. claimed they have experienced relieve of 'stiffness'. The Japanese Government's Ministry of Health and Nevertheless we would like to make it absolutely clear Welfare has given its approval (NO. 51B-614) to this that all papers published so far show that the devices necklace and we have read four fully documented reports vary in their effect from one person to another and that from independent authorities (such as the University of ín some cases they have no effect at all. There is no Tokyo's Medical Faculty) to support TDK's statements. totally tangible scientific evidence to support or refute The necklaces are made in two basic forms. Gold- any claims or statements made although research is plated 430mm long and rhodium -plated 560mm long continuing worldwide. Therefore as no claims can - these, TDK suggest, would suit men or women. currently be substantiated (and of course no claims are respectively. Both are sold at the same price. made by us or Caldor) the ultimate decision and The necklaces contain extremely powerful rare earth experience must be yours. cobalt magnets which were originally developed for the Nevertheless, the necklaces are made by TDK and NASA space programme. The magnets are permanent. that must mean something. Necklaces are supplied complete with two connecting rings, one hook and one length of chain as spares. TDK advise users to wear the necklace in direct contact with the skin. It should be worn continuously including whilst asleep, removing it only whilst taking a shower or bath. Manufactured by, Most people find it effective after two to three days. The TDK magnetic necklace is handled in Australia by the Caldor Corporation and they have -made arrangements for our readers to obtain either type at the same price - $49.95 including postage and packing. TDK TDK ELECTRONICS CO., LTD. Electronics Today International 600 and' 3600 SYNTHESIZERS .`

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Here are full plans for building two full-scale musicians, university music departments and as electronic music synthesizers. home hobby projects. Many thousands of these remarkable units Here, the complete series has been reprinted in a have been built world-wide since the series completely corrected and up -dated form. of constructional articles started in Electronics Today late in 1973. The book is available in a limited edition of 2000 Since then, the two units have gained a reputation copies only. as being among the most flexible and versatile of electronic instruments available. ENSURE YOUR COPY NOW! They have been built as school and university Send $12.50 to Electronics Today International, group projects, by recording studios, professional 15 Boundary Street, Rushcutters Bay NSW, 2011.

26 ELECTRONICS TODAY INTERNATIONAL - MARCH 1978 '- p '- I s f IRATED REO I G

How record manufacturers are planning to beat the bootleggers. By Roger Harrison.

IT WAS ONLY a few years ago that pirate or 'bootleg' versions of Bob Dylan's Basement Tapes and Pink Floyd's Dark Side of the Moon, sold like the proverbial hotcakes, along with a host of others. These recordings blatantly advertised the fact that they were pirated, and thus of illegal origin - transgressing not only performer's rights but also copyright. Many people were attracted to pirate recordings for there seemed to be something rather exciting about owning a recording which the artist did not approve. Often, the pirate recording! contained material not released on genuine recordings, or were of concert performances which often differ markedly from studio performances. Quality was almost inevitably low-fil Through a combination of circumstances, these bootleg recordings gradually disappeared from the market. Groups employed stewards to hunt through audiences looking for tape recorders, legal prosecutions were brought against bootleg distributors etc. Finally, high prices for low -fi killed the market. Recently, however, the pirates have changed tack and are presenting recordings that are either made to mimic legitmate releases on well known labels or to appear like legitimate competition. For example, a recording stolen from EMI may either be packaged to look like an EMI recording, or packaged in a sleeve with an authentic -sounding company label, but not that of an authorised EMI trader. In neither case does the

27 ELECTRONICS TODAY INTERNATIONAL - MARCH 1978 The ident ('194') over the recording every problems few seconds. Thus, if ever a bootleg recording is issued, its origin will be of PIRATED RECORDING audibly stamped all over it! With the station ident so loudly intrusive there would likely be little incentive anyway. In recent years, EMI's proposed artist, EMI or anyone else (save the and impress an audible signal on the system for identifying the source of a bootlegger and his outlets) receive any tape. recording has often been discussed in reward. In this way, two inaudible frequencies the popular press. But there is much Those recordings that mimic are combined to produce an audible confusion over just what it is that EMI legitimate. releases are usually a straight, frequency which destroys the recording have succeeded in doing to curb piracy. undoctored copy of the original, with attempt. Briefly, the system involves putting a slightly reduced fidelity. When released A little thought shows the snags in digital code on the recorded material at on a phony label, often the recording the system. To produce an audible a very low level which can be recognised is altered in the transfer to disguise beat with the very high bias frequency by specially designed decoding machines. its origin, usually by dubbing applause used on tape recorders (around 70 kHz It is extremely difficult to evaluate or extra instruments onto the copy. or higher) requires that a similar signal and thus prevents forging or replication The problem arises here in that both be recorded on the disc. The studio of the code. these techniques are far harder to detect cutting machine won't cut it, the Unfortunately, the EMI system is and prove as bootleg than the previous factory pressing machines won't press it usable only to prove that a recording methods. The British Phonographic and the would-be-recordist's cartridge did not originate from EMI. In the case Industry (the UK recording industry wouldn't reproduce it. of mimic recordings, which would look trade association) have taken numerous It is also. easily filtered out at any like a genuine EMI release, the lack of court actions, with some success, stage of the production chain, either any EMI watermark code would be resulting from pure detective work. intentionally or otherwise, with no loss good grounds to believe that the of quality, because the carrier signal is recording did not come from EMI. But SELF-DESTRUCT inaudible anyway. Different tape courts do not like negative proof - However, the final solution to pro- recorders have widely different bias where the absence of something is fessional piracy relics on technological frequencies which also defeats the regarded as positively proving some- aids. This can be achieved by either system. thing else. There is also the argument making the physical act of illegitimate The drawbacks are enough to dis- that unless all EMI plants around the copying technically impossible, or to courage further reinvention of this world were using the system at the time, make the technical detection of such system and doubtless account and there were no old stocks of copying unambiguous. Unfortunately, for the demise of the Apple patents. unwatermarked tapes, then it is despite considerable efforts, little real There is another daunting aspect to unreasonable to say that just because a practical headway has yet been made in anti -copy systems. It is likely that if tape has no watermark that it is not either of these directions: anyone does devise a system that will from EMI. Then again, why shouldn't If record companies had their way, prevent the copying of a disc or tape an EMI watermarked tape find its way each disc or pre-recorded tape released onto existing tape recording machines, into pirate hands? and sold- to the public, would self- the recorder manufactures will soon destruct, refuse to play or produce devise a defeat button or circuit to NOTCHES unacceptable sounds if copying was make copying possible again. There is another approach which a attempted. number of recording companies are To date, anti -copy remains an im- WATERMARKS seriously considering. This is the possible dream. Inventors still tackle the Anti -copy systems appear defeated for Audicom system invented by - Murray problem, the cash rewards for a workable the moment. However, the concept of Crosby. system would be enormous. Inevitably, an indelible watermark on the recorded It was originally intended one red -herring for scheme keeps being sound appears somewhat less fanciful. collating automatically the number re -invented. of As with anti -copy, watermark times a commercial was transmitted on Back in 1967/68, the Beatles' systems have gone through numerous a radio or TV station,, for accounting Electronics Company, Apple, leaked a futile reinventions. The aim is to record and statistical purposes. story about three patent applications an inaudible identification signal along The system works like this: At a on a new anti-cópy system. Any with the recorded sound. The water- frequency around 2-3 kHz, a tight notch attempt at recording a disc pressed mark signal is inaudible to the listener filter with a very narrow bandwidth according to this system would result in when the disc or tape is played on con- (around 100 Hz) bites a small chunk out a high-pitched whistle they claimed. The ventional equipment, but it can be of the audio spectrum. At the same time idea attracted a certain amount of identified or decoded by special a binary code watermark signal is attention, but, in time, the patent equipment. modulated onto an audio frequency applications were allowed to die, along Ultrasonic (high frequency) and subcarrier of the corresponding with the publicity and Apple Electronics infrasonic (very low frequency) water- frequency and bandwidth so that it fits disintegrated. marks have similar limitations to the neatly into the window left by the Although details of the idea remain a anti -copy schemes. For this reason, it is notch filter. The amplitude of the secret, the system probably involved essential to adopt a sledge -hammer subcarrier frequency is varied so that it recording an ultrasonic approach carrier to prove the origin of copied tracks the audio level of the surrounding frequency on the disc. Thus, at material. any One such attempt, by Capital programme. In this way, the coded attempt to put the disc material Radio on tape (UK) who recently broadcast identification signal is always submerged the carrier on the disc would beat with some previously unpublished Beatles by the programme, but it is still re- the tape recorder's ultrasonic bias signal tapes, involved putting a loud station cognisable by a decoder tuned to the

28 ELECTRONICS TODAY INTERNATIONAL - MARCH 1978 A 12 dB dip ín the mid -band frequency range, between 2 kHz and 4 kHz, can be introduced intermittently with surprisingly little audible effect. While a notch of higher or lower frequency may be relatively inaudible while consistently maintained, any attempt at intermittent notching outside the 2-4 kHz range produces highly offensive sounds. Below 2 kHz a notch intrudes into the fundamental frequencies of musical notes from many instruments. Above 4 kHz intermittent notching results in modulation of high frequency background noise and intrudes into the upper harmonic range of musical tones. By careful selection of where a notch is introduced into a recording, its presence can be made unobtrusive. It thus seems likely that a notch 'filled' with a coded carrier like the Crosby system could be placed on a recording without the listener being aware of its presence.

The presence of a notch in a recording can be simply detected with a'spectrum analyser. A notch filled with a code requires a decoder to identify the origin of the recording. The placing of a notch, or code -filled notch, on a recording would need to be dictated by the characteristics of the material recorded, in order that the presence of the watermark is masked. The notch characteristics may need tailoring to suit the programme material. Any system of indiscriminate notching would produce audible effects on the material and thus would be rejected by hi-fi listeners. There is no reason why the characteristics of the notch introduced narrow band notch frequency and below the programme level. Thus, the on any commercial recording should not designed to interpret the digital subcarrier is always submerged by the depend solely on the nature of that information modulated on the sub - programme but would still be detectable recording, with regard to location, carrier. by a decoder tuned to the narrow band frequency and duration. Provided the Sound like a. great system for discs notch frequency so that the digital recording company accurately logs the and tapes. However, several difficulties watermark code is recognisable by the position of the coding windows it will arise. If, for instance, the coded sub - digital decoder. have no future difficulties in detecting carrier is at such a low level, might it The encoding system is illustrated in - the coding. This in itself would prove a not be lost in noise after transmission figure 1. The notch and coded sub- deterrent to pirates. or the copying process? is This one area carrier are switched in at intervals When illegitimately copying a which EMI, RIAA and others are according to the periods of the timers. recording, the pirate will be faced with investigating. Even if they get results, As the frequency and position of the the knowledge that interspersed with we are not likely to read. or hear about notch and the code on the subcarrier the material will be a notch of unknown it. Because, if the system is adopted, it can be programmed by the encoder frequency and bandwidth, at unknown would not be prudent for the record operator, only a decoder set up to locations on the recording, including companies to indicate the level at which recognise that code could detect its an indentification signal which can be noise destroys the code. presence. The system is applicable to positively identified by the owner of the One set of technical specifications broadcasting, tapes and records. copyright. Secondly, even if you know indicates that when the programme Does the 100 Hz notch missing from where the notch is, it is well-nigh audio is level zero, the subcarrier coded the audible frequency spectrum affect impossible to repair. signal will be 55 dB below the peak the sound? Experiments have shown Such a situation allows the copyright level the carrier would be at peak audio that, in fact, such a notch will largely go owner to point, albeit electronically, to programme level. When the programme unnoticed. This leads to the possibility a watermark in the sound on an audio is at peak level then the audio of just using a notch to watermark a illegitimate recording and thereby subcarrier in the notch will be 40 dB recording. identify, positively, its source.

ELECTRONICS TODAY INTERNATIONAL - MARCH 1978 29 HARKSOUND a new name in turntables! looks suspiciously like the celebrated CCC doesn't it?

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in fact 11 is! CEC, Australia's top-selling range of imported turn- in the HARKSOUND range-right from the BD2200 belt tables,' will now be known as HARKSOUND. But don't drive, up to the unique DD8200 direct drive. despair ... nothing's changed but the name. Still the same five year warranty, still the same proven The HARKSOUND features include: performance, and when you consider that CEC are Japan's High quality, statically balanced S-shaped tone arm. oldest and most experienced turntable manufacturer, you Adjustable anti -skating. know you're buying the best. High quality magnetic cartridge. The HARKSOUND range by CEC offers everything you Fully decoupled motor to turntable/arm suspension. want and need for noise -free, Hi -Fidelity performance, plus Low profile design with balanced acrylic dust cover. operational ease ... and there's a turntable for everyone Excellent value and performance for the price. HFIA Survey figures Sept 1977 HARKSOUND by CCC CHUG ELECTRIC CO LTD.

ruw97e Chstr,bu,ea by- HARMAN AUSTRALIA PTY. LTD., P 0 Box 6. BROOKVALE, N S W. 2100. Telephone: (02) 939 2922 t

Features-- 400,000 Sold in 1977 Made in Australia Screwed (not welded) body Jamproof floating mechanism Quality ferric oxide tape 5 brief cases SUPER,/ -\4 $6.99 LARGE HOLDS32 C46min. ONLY 79c C60 min. ONLY 89c ONLY $2.99 HóL°DiuM S2pages \ A N LWEST PRICED C9Omin. ONLY 1'09C CHOROME IN AUSTRALIA ONLY7 1-39c C12O min. C60 - $1.59 C60 min. $1.69 + Q track C80 - $1.89 min. $1.99 - lesi C90 - DISCOUNT TDK Q H/Ckanet 99(

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Dick Smith brings you the Chroma-Chime - an outstanding example of tomorrow's micro -computer technology. Now YOU can be among the first enthusiasts in the world to build your own computerised musical door chime. And you=ll vote it one of the most incredible inventions you've ever seen! Pre-programmed into the Texas Instruments TMS-1000 microcomputer chip are 24 of the world's favourite and best known tunes. You set two knobs and - fantastic - when visitors press the bell button at your door they are greeted with the melodic notes of the tune you've selected. Just imagine how astonished (and flattered) your visitors will be! Complete kit: Build the Chroma-Chime in about 3 hours! One of the best things about having the Chroma-Chime in your home is that you can tell all your amazed callers that you built it yourself. The kit has been carefully prepared so that practic- ally anyone capable of neat soldering can build it with complete

success. The profusely illustrated instruction manual contains 1 step-by-step Control panel cover construction details together with a fault-finding also supplied. 2x 9V guide, circuit description, installation details and operating batteries required - instructions. It would be hard to go wrong! batteries last in excess of 1 year with average Cat K-2020 usage.

HERE IS THE CHROMA-CHIME'S AMAZING REPERTOIRE: * Westminster Chimes * Greensleeves * Maryland * Oranges and Lemons * Twinkle'Twinkle Little Star * * Mendelssohn's Wedding March * Sailor's Hornpipe * Cookhouse Door * Colonel Bogie * Beethoven's 9th * * William Tell Overture * Soldier's Chorus * Beethoven's 'Fate Knocking' * Bach * Mozart * Lorelei * * Great Gate of Kiev * Oh Come, All Ye Faithful * God Save the Queen * Rule Brittania * Land of Hope & Glory * The Stars & Stripes * The Marseillaise * Deutschland Uber Alles *

SPECIAL NO-OBLIGATION 7 DAY INSPECTION COMES WITH See the Chroma-Chime demonstrated at any Dick Smith store. 14r'"';'1.--'ofia. - FREE 28 PAGE Take advantage of our special'7 day no -obligation inspection offer: 1 d= -"e CONSTRUCTION inspect the Chroma-Chime kit for up to 7 days, and if '.., MANUAL AND for any reason you do not wish to build it, return it in the mar,mP original condition and it its original packaging and we will GUIDE. refund you the price of the kit!

SHOP HOURS 004er rnlue PAP c54r9e 99 S5 pppp Mo.. F. 9AM h 30PM 5 Ser. 9AM - 12 noon' $jy_ 0999e DICK 1Brnluno y hour ..01.e.1 $(10p SMITH ELECTRONICS welcome here SSh001 w 9.w9 5.SSSS50 SYDNEY. SYDNEY: SYDNEY: SYDNEY: MELBOURNE: 125 York St, . 361 Home Hwy, MELBOURNE: BRISBANE: ADELAIDE: 162 Pacific Hwy, 30 Grose St, 399 Lontdale St, 656 Bodge Crty. Ph 29 1126. Bankstown. Ph Rd. 166 Logan Rd, 203 Wright St, 709 6600. Gore Hill. Ph 439.5311 Parramatta. Ph 6831133 City. Ph 67.9834 Richmond. Open 'Id 8PM Thursday Open '1,1 Ph 42.1614. Buranda. Ph 391.6233 City. Ph 212.1962 8PM Thursday Ample parking at door. 1st floor - friendly store! New: in right town! Easy access: huge stock. Opens 8.30AM Now Open. See usl MAIL ORDER DEPARTMENT: PO Box 747, Crows Nest, NSW 2065. Phone 439.5311. Post & Pack eara. WE HAVE DEALERS RIGHT ACROSS AUSTRALIA - THERE'S ONE NEAR YOU! Project 714

i i i Purt2

By Roger Harrison, VK2ZTB, who still swears (SWR's?) the prototype hasn't fallen down yet!

Balun Construction The wound core is then glued to a Mount the balun on the antenna THE BALUN TRANSFORMER consists small square of matrix board, about 25 bogm, near or underneath, dipole 10, mm long per side, using a small amount and connect the two 'balanced' of a trifilar winding on a ferrite balun core, Neosid type 1050/2/F14. Alter- of five-minute epoxy or one of the connection leads to the feedpoint of glues. The windings are dipole 10. Tape the assembly to the natively, a similar core could be stripped 'super' terminated to two pins on either side of boom using weatherproof tape or plastic from a standard 4 - 1 TV balun and as illustrated in Figure 7. ties. Even string could be used, or the rewound. Construction is relatively non- the board, glued in position using some critical, and details are illustrated in Fig. Two lengths of hookup wire should.be assembly Fig. 7. soldered to the 'balanced' terminals, more five-minute epoxy. reach from the mounting An balun system would The winding wire is any convenient sufficient to alternative 4 - 1 TV baluns. small -gauge hookup wire, preferably in point of the balun to the feedpoint of be to use standard These a to 75 ohm three different colours to identify the dipole 10. A short length of coax, perform 300 ohm a transformation. With the type of different strands and assist construction. terminated in Belling -Lee line socket, employed, they can be Alternatively, ordinary enamelled is then attached to the 'unbalanced' construction used for a balanced -to -balanced or a copper wire, about 22 gauge to 28 gauge terminals as indicated. assembly can be balanced -to -unbalanced transformation. B & S, would be satisfactory, although The balun the three separate wires would have to conveniently 'potted', using five-minute be identified in some way, for example, epoxy, to weatherproof it. by knotting wire 'b' once at each end, and wire 'c' twice at each end. The three wires need to be about 150 mm long and should be lightly twisted :)alanced together before commencing the winding. Wind 6% turns through the two holes, around the outside of the balun core as illustrated in Figure 7. CIRCUIT

unbalanced

CONSTRUCTION Ferrite balun core a b c (Neosid 1050/2/F14)

WINDING BALUN

Fig. 7. Construction of 1:1 balun transformer.

ELECTRONICS TODAY INTERNATIONAL - MARCH 1978 33 Plo ject 714 UHF LOG -PERIODIC ANTENNA

300 ohm twin line Splitters from antenna Coax f om antenna To run two different receivers from a common antenna a device called a splitter is necessary. The two receivers cannot simply be connected in parallel as they will interact with each other, apart from causing an impedance mismatch with the antenna feedline. Two different kinds of splitters can be constructed - the resistive type and the transformer type. Alternatively, a suitable splitter may be purchased. As they are wideband devices they are suited for operation over the entire range from 40 MHz to 250 MHz. Twin line Twin line to TV receiver to FM receiver To FM receiver CIRCUIT Aluminium panel (back view)

CIRCUIT ANT

Aluminium panel (back view) o o o o

Belling -Lee coax socket RX RX o \ o o

RX RX CONSTRUCTION 220 ohm Screw %Wor'4W terminal 0 resistor panels

300 OHM SYSTEM SPLITTER 27 ohm CONSTRUCTION /zWo4W Fig. 8. a1 Circuit of 75 ohm resistive splitter. resistor bl Layout of 75 ohm resistive splitter. cl Circuit of 300 ohm resistive splitter. 75 OHM SYSTEM SPLITTER di Layout of 300 ohm resistive splitter.

If using these baluns, connect the 75 Resistive Splitters DX, then the loss these splitters intro- ohm side feed to the point of dipole 10 Two resistive -type splitters are duce will reduce receiver sensitivity. and run ordinary 300 ohm ribbon to illustrated in Fig. 8. That on the left Either type may be constructed on your receiver installations from is the 300 for unbalanced, 75 ohm coaxial a small square or rectangular ohm balun connections. Be sure to cable feedline systems; the one on the aluminium plate. Size is unimportant take all the required precautions is right for 300 ohm systems. Both of providing the feedline connectors are necessary with this sort of feedline these splitters are compromise mounted reasonably close together installation as for TV feeder, to prevent solutions and are only recommended so that the lead -length of the resistors signal 'suckout' by nearby metal for TV & FM receiver installations in and interconnections is kept short. structures and by line imbalance. strong signal areas. If you are after Solder all connections.

34 ELECTRONICS TODAY INTERNATIONAL - MARCH 1978 Note that any terminal may be used The coax required depends on the this type of cable with a grey plastic as an input and the other two exact details of your installation. If a outer sheath. This is meant for terminals may be used as the outputs. short run of coax is possible then a 6.5 community antenna installations, such When the splitter construction is mm diameter cable such as RG59 as in flats and units, and the sheath completed, it can be mounted in a (variously designated as RG59/U or deteriorates rapidly convenient when exposed to place such as a cutout in a RG59/CU etc.), which is a 75 ohm the weather. wall, shelf, or equipment cabinet. characteristic cable, is suitable. If this If you wish to use a 300 ohm cannot be obtained, then 50 ohm feeder system, any of the commonly Transformer Splitter cable such as RG58 may be substi- available TV ribbon feeders should The best splitter is a transformer -type tuted, although a slight mismatch will suffice, depending on your require- as it introduces a minimal loss, and can result. The effect will be unnoticeable ments: Solid dielectric type is be constructed in a similar way to the on a VHF or FM receiver but slight adequate in strong signal areas and is balun previously described. 'ringing' may be apparent on high the least expensive. If you want the Commence by winding three wires contrast areas on a TV picture. This maximum in sensitivity a low -loss on a Neosid balun core may not be visible at type normal viewing type should be installed. There are 1050/2/F14 as illustrated in Fig. 7 and distances. various versions of low -loss 300 ohin wind on 61/2 turns, For trifilar as described maximum sensitivity on feeder. Some types are similar to the for the balun. The reception connections and or if you have to run the solid dielectric type and simply have construction as are illustrated in Fig. 9. feedline more than 15-20 metres, then cutouts in the dielectric. 'Open wire' Once the a transformer is completed, low loss 75 ohm cable is types have small spacers supporting secure the windings, if necessary, with recommended, such as type ET13M or the two wires at intervals. Another a small application of super glue. Then PT13M with black, weatherproof type has a continuous dielectric of glue the transformer to a small outer jacket. It is made scrap by foam material encased in a thin plastic of plain phenolic board or matrix Cablemakers Australia and is about 'shell'. board. This assembly is glued to a 10mm diameter. There is a version of small aluminium panel on which are mounted three Belling -Lee sockets as Input (75 ohm) illustrated in Fig. 9. Carefully separate and identify the three leads at each From antenna Receiver 1 ohm) end of the transformer windings and (75 connect them as shown. Carefully solder all joints. When the construction of the Outputs splitter is complete it can be mounted as described for the resistive splitters. Receiver 2 (75 ohms) Feedline Systems There are two alternatives for your 27 ohm feedline system: a 75 ohm coaxial 'Y2Wor'4W cable system, or a 300 ohm twin -line resistor system. The coaxial cable system is CIRCUIT recommended for a number of reasons: the coax may be run anywhere convenient as it is unaffected by wall material, metal objects and power Aluminium panel (back view) cords. Most VHF receivers, TV sets and FM tuners these days have a coax connector antenna fitting to suit, and no interference can be picked up on the coax feedline as it is effectively Phenolic or matrix board shielded. Ferrite insulating sub panel A 300 ohm twin -line feeder has the balun advantage of being inexpensive, but it core must be correctly installed with stand- off supports and twists in the line to aid in maintaining 'balance'. It cannot Solder lug be run as conveniently as coax, and noise and multi -path signals may be picked up on the feeder. The required use of baluns and Belling -Lee socket splitters in the system is illustrated in 27 ohm Fig. 10 for both systems. The 75 ohm %Wor'W CONSTRUCTION resistor coaxial cable system is illustrated on the left and the 300 ohm twin -line system on the right. Fig..9. a) Circuit of transformer -type splitter. b) Construction of transformer -type splitter.

ELECTRONICS TODAY INTERNATIONAL - MARCH 1978 35 Project 714 UHF LOG -PERIODIC ANTENNA

are concerned I live in Antenna Performance using it for TV/FM reception the FM transmitters a strong signal area, although we have The beamwidth of the antenna is beamwidth sh6uld prove adequate for in the past suffered from ghosting on about 50° the -3dB points). most capital city locations. However, (between from the south. The good There were no discernable sidelobes in if you live in the Balmain-Leichhardt- TV signals -to -back ratio improved this the forward direction whichreduces Annandale-Glebe area of Sydney as I front problem considerably. problems with multi -path signals on do, you may think that you will have Listening to a variety of VHF signals FM and TV reception which are the problems with a fixed antenna. The with a general coverage VHF receiver cause of distortion on FM stereo and TV transmitters are to the north (Gore produced good strong signals on the ghosting on TV signals. Hill area) and 2MBS-FM is to move to frequencies from Bankstown The gain of the antenna is around the AMP building site in the city, to aircraft light aircraft aerodrome much as eight to nine dB and the front to back the east. However, their 'technical rep.' - Quite readable signals from ratio (rejection of signals behind the assures me that their 10 kW transmitter expected. as far away as Wollongong were also antenna) around 30 dB. will put such a strong signal into those and sound from channel The broad beamwidth allows areas that an antenna will not be copied. Video Wagga were audible, sometimes at reception over a wide range of angles necessary! 0in good strength, in Sydney on the in the forward direction, very handy Installed at a height of roughly six quite MHz model! when the DX starts pouring in from all metres above ground level, the antenna 60 - 250 over the place as it saves a great deal gave a good account of itself. of rotating the antenna. If you are Admittedly, as far as the local TV and

Antenna 75 ohm // 4:1 -- TV balun

N1:1 balun (Fig. 7) 300 ohm l / TV ribboribbon 300 ohm 4:1 r- 75 ohm TV balun coax (RG59) OR '75 coax 75 ohm 300 ohm (RG59) splitter n (Fig 8) 75 ohm splitter 75 ohm splitter (Fig 8 or Fig 9) (Fig 8 or Fig 9) to 300 ohm o inputs on O O O O receivers FM receiver FM receiver O

TV receiver TV receiver

Fig. 10. Feedline and splitter systems insta/ladon.

36 ELECTRONICS TODAY INTERNATIONAL - MARCH 1978 A series of tests conducted by a leading independent audio -testing THE ADC CARTRID laboratory prove it ' The tests show that the ADC XLM-MKII cartridge causes no perceivable wear until after 60 plays. Industry sources estimate the "life of a record" (the average number of times a CAUSES NU record is played) to be 40 to 50 plays. Other cartridge manufacturers may talk about less record wear, but ADC has PERCEIVABLE WEAR proven no wear over the average life of a record. The reason for this is our unique patented design. It's patent #3294405. OVER THE LIFE We call it the "induced magnet" cartridge. Most cartridges are designed so that OF A RECORD. a heavy magnet is part of the moving system. The ADC XLM-MKII is different, because our engineers found a way to detach the magnet and repo- sition it above the stylus, so the stylus applies less pressure against the groove. Less pressure means less wear. The fact is, of all the leading brands, ADC cartridges have the lowest mass moving system you can buy. That means better sound and superior performance. The XLM frequency response is exceptionally flat, from 15Hz to 24KHz ± 1.5dB. And for the ultimate in stereo reproduction, it has a minimum of 28dB of channel separation. Think about it. In the long run you'll probably spend more on your record collection than you will on your whole stereo system. So it makes sense to buy a cartridge with proof that it makes your records sound better and helps them to live longer. The ADC low mass cartridge. Unbelievable. -- -- A D C LOW MASS CLIITRIDGE A BSR COMPANY IT HELPS YOUR RECORDS LIVE BSR (A'asia) Pty. Ltd., LONGER. Anne Street, St. Mary's, NSW 2760. THE PROOF: THE DIFFERENCE: ADC 1.--.153" I RECORDED REO`O0fDED XLM-MK-II SURFACE III SUR' CE SHURE-7I I ilÍÍ1 ti V -I5 -III .257"

AUDIO-TECHNICA AT -15-S -.274"

STANTON 68l-EEE 282" The way to get the most accurate reproduction of sound is to This is a photomicrograph of a This is a photomicrograph of a lower the total effective mass of the moving parts of the stylus. 20kHz record groove that has similar 20kHz record groove And that's exactly what our engineers did. In fact, of all the never been played before. played 75 times with an ADC leading brands, ADC cartridges A XLM-MKII cartridge. As you can have the lowest mass moving INDUCED MAGNET see there is no difference. system you can buy. MAGNET IAIIIIIIII * CBS Technology Center Project 1108: Record Wear Test Program. Performed for Audio Dynamics Corporation. December 1976. COM PTON BSR137 , ,!. :. NOW: You can really get into microprocessors.. BUILD THE EXCITING NEW E.A. VIDEO FAMOUS SC/MP - less than DISPLAY TERMINAL PROJECT: By simple combination of the following kits with a cost! microprocessor, the hobbyist can build up a complete microcomputer system which will mate with a normal kit which The full evaluation TV receiver or video monitor for display. c! enables you to build a real microprocessor system. Was a VIDEO DISPLAY UNIT (known as a TV typewriter) bargain at $92 - now look at Basic video display board from Elect. Aust. Feb '78, complete MILAN the price -way under cost! with double sided, plated -through hole PCB, all ICs and comp- Includes the SC/MP chip, RAM, onents but not including 4.3MHz xtal (not a necessity) ROM, buffer, interface, voltage regulator & xtal, PCB plus all. Optional 4.3MHz crystal .. .. Cat K-6026.. ,. .. ,. . $4.75 required discrete components. I Plus you get all the manuals VIDEO MODULATOR KIT i (instruction, programming, This kit allows the Video display unit to be used with any !technical, etc etc ) in a ring - standard TV receiver through the antenna terminals. back folder for easy reference. ASCII KEYBOARD ENCODER 00 Learn about SCAMP: The ASCII keyboard encoder project from EA, March '78. Get the SC/MP programming This kit is complete with all components, including power and assembly manual. Loads supply and transformers, but not including the UART IC. of information & data. Value! For use with our computer keyboard (see below) Cat B-3232...... $12.22 Cat Z-9200 UART IC ONLY 145 IN STOCK: BE QUICK AT THIS PRICE! S1883/MM5303N/TMS6011 UART (universal asynchronous receiver transmitter) IC for above encoder if required.

PAPER TAPE READER SPECIAL PARTS FOR ABOVE KITS: ..- Cat H-8336 Video Display Unit PCB only .. ., ., . $32.50 Cat K-3466 Cat H-8337 Video Modulator PCB only ...... $1.20 NIT Cat H-8338 ASCII Encoder PCB only ...... $4.50 ,.. / NEW! Build this brilliant tape Cat H-3130 Keyboard Console Metalwork, complete with , ó. reader. Interfaces with all t if . marviplate lid ...... $24.50 i,zi, microprocessors via an 8 -bit para- Cat X-1180 b llel port. Precision optical reader 63 key computer keyboard, individual key uses ordinary room light. Comes contacts gold plated. NOTE: This is NOT complete with all instructions, a kit, keyboard fully assembled ...... $55.00 i schematics, etc, housed in attractive D0.. case. Incredible value : 'GETTING INTO MICROPROCESSORS' S By Jim Rowe, Editor of Electronics Australia magazine. If (see elsewhere for $1061 you want to get into microprocessors & minicomputers, you need this book! Cat. B-2350 ...... $4.50

St SPECIAL 'COMPUTER' SEMICONDUCTORS r Or 0 Z-9202 MM5740AAF Encoder $27.50 7üi Z-9206 2513 Character Generator $12.50 Random Access Memory $ 4.50 .,tlIOWVLAr Z-9302 2102 1110.0 10 Z-9304 2112 Memory (suits Miniscamp) $ 6.50 3.411 IMO Z-9306 2114 Memory (4k - suits M'scamp) $14.50 r------Z-9308 MM -5204 Prog. E -Prom $19.75 Z-4804 4N28 Opto Coupler $ 1.50 AYt,

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Futuretronics have done it again. The World's first microprocessor based Backgammon game is here right now. It's you against the computer. A sophisticated, totally computerized Backgam- mon game, utilizing a Motorola 6800 microprocessor with 2K ROM and 6K RAM, designed for excitement and ease of play. It will defeat the average player more often than not, and compete evenly with experts. When you play against the computer, each move is displayed and recorded electronically. The position of every piece on the board can be verified at any time and since the dice are "rolled" electronically at random, each o. game is different. The computer plays an aggressive offensive game, but will change its strategy depending on how you choose to play. Running game, block and hit, back game, it know them all, and plays them all well. Playing against the computer is a true measurement of skill. If you are a beginner it is a remarkable learning instrument. This beautifully finished, top-quality product complete with its own carrying case is available now. for $299.00 delivered free anywhere In Australia. COMPUTER CHESS

It's you against the computer. .Li . . i The first microprocessor based chess game, - using an 8080A C.P.U. It utilizes and 8224 clock generator/driver, 8228 system controller, 512 -- - - 8 -bit bytes of random access memory, that stores the position of the chess pieces, and a 16,384 -bit !'o read only memory. Software contains such ele- - , ments as the rules of chess, the relative impor- .° : tance of the pieces, allowable moves and 1 ' C-; strategies. The micro computer plays by the ti book, working on the weighed value of the ,FS_ pieces, and completely scanning the board for the best available move each time. It plays ag- gressively, tries to control the centre of the board, and, if it's in trouble, will try for a stalemate. The keyboard can be used to verify the position 480 4110 of each chess piece at any time during the game. User selectable 3 levels of difficulty, choice of black or white pieces. New shipment just arrived, 00 new low price $345.00 delivered free anywhere in Au- stralia. r 1 To order or for Please send Gammonmaster. I enclose $299.00 Information contact: E Please send Chess Challenger. I enclose $345.00 rc Please send both games. I enclose $599.00 NAMES BROmS pty. ltd. ADDRESS 1 Dallas Crt, Hughesdale 3166, VIC. Phones: (03) 823732 - (03) 579297 STATE L PY LIS ó4rh,ÑMsy, OR walLi

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Ultrasonic sound is being used increasingly in medical ultrasound diagnosis. By Dr P. N. T. Wells, Bristol General Hospital. THE importance of ultrasonic diagnostic methods lies in the fundmental differences between them and other techniques such as radiology Clock and radioisotope scanning. The symptoms of some diseases, and of Far -side Mid -line natural conditions such as pregnancy, structures structures are best investigated by ultrasound. It maps out anatomical cross -sections, Near -side measures the performance of the heart structures and the flow of blood, and identifies Transmitter many kinds of abnormality, including several types of cancer, all without encroaching into the body in any way. Twenty-five years ago, doctors Ultrasonic seeking to investigate the structures of probe the body had no alternative to X-rays. Swept -gain substances to give better Injections of Ultrasonic generator necessary obtain contrast were often to beam information about soft tissues. Nowadays, ultrasonic methods have replaced radiology in helping to solve many clinical problems: doctors depend on ultrasonic diagnosis, and patients Receiver demand this kind of investigation. The procedures are rapid and painless and nothing enters the body other than ultrasound waves. Unlike ionizing radiations, ultrasound at diagnostic exposure levels seems to be harmless. Time -base Near -side Mid -Line Vertical generator signals echo deflection Basic Principles plate Most diagnostic applications of ultrasound depend on the reflection of ultrasonic waves at surfaces between tissue structures which differ in their so-called characteristic impedance. The characteristic impedance of a material is EZD equal to the product of its density and the velocity of ultrasound within it. The densities of soft tissues, about 103 kg m-3 (kilograms per cubic metre), and /I the velocities of ultrasound within Far -side Cathode-ray Hor zontal Elect on gun them, about 1500 m s-1 (metres per Display for water. screen echoes tube deflection second), are similar to those plate When an ultrasonic wave strikes the boundary between tissues that differ Basic arrangement of the A -scope system, in use in this instance to show the mid-line structures in characteristic impedance, a propor- of the brain in their relative position half way between the sides of the skull, as indicated by Asymmetrical spacing of the tion of the energy in the wave is symmetry of the deflections of the cathode-ray tube trace. may mean that disease has brought about a physical change such as a tumour on reflected in much the same way that deflections one side of the brain. The swept -gain generator gradually increases the receiver amplification over light is reflected when it meets a change each sweep of the time base to compensate for the attentuation of the deeper echoes by in reflectivity at a surface. intervening tissues.

41 ELECTRONICS TODAY INTERNATIONAL - MARCH 1978 Inside information from ultrasound Clock The characteristic impedances of soft Transmitter tissues are similar, so the echoes from their boundaries are very small. For s example, only about 0.5 per cent of the Ultrasonic probe energy striking the boundary between Time -base Receiver kidney and fat is reflected. Such echoes generator are largh enough to be detected by a Moto sensitive receiver. But almost all the gearbox Y energy crosses the boundary and drive Deflection -- Grid is available for reflection by deeper plate Iú- structures. Cathode-ray tube 'tIQ Much larger reflections occur at - with fibre -optic face plate boundaries between soft tissues and r either bone or gas, because of large Ultrasonic differences in Heart characteristic impedance. N beam These large reflections restrict the use of Brightness- ultrasound in medical diagnosis. More- modulated trace Ultra -violet over, it is necessary to exclude air from Idling roller recording paper between the probe and the patient. This Constant -speed paper drive roller may be done either by examining through a water bath or through a film of oil smeared on the patient's skin. Time -position recording system based on the B -scope display, shown in use for echocardiography. The fibre -optic face plate of the cathode-ray tube collects enough light to produce a self- Resolution developing trace on ultra-violet recording paper. Ultrasonic echo -ranging techniques depend on the measurement the of time Clock interval between the transmission of a brief pulse of energy and the reception Supporting structure with articulated joints of its echo, just as in radar. In any and slides allowing % Trine base selection of scan plane imaging system, whether using light, genera ors ultrasound or any other kind of radiation, the resolution is limited by ResolversReso the wavelength of the radiation. It is for Jg:. this reason that ultrasound, as opposed -1/%0-" ,. Aniculated to sound, is- used in medical diagnosis. arrns We need to visualize structures of only a . . Receiver few millimetres in size, so that wave- Typical scan line Ultrasonic probe length has to be around a millimetre Deflection or less. In soft tissues, ít is about 1.5 plates 1.5 mm at a frequency of 1 MHz and proportionately less at higher frequencies. The highest audible Typical path of ultrasonic beam frequency, about 20 kHz, has a Gnd wavelength of 75 mm. In principle, Dirro-view electromc the performance might appear likely storage tube likely to improve as the frequency is increased. But ultrasound is attenuated as it travels through tissues Two-dimensional scanner and B -scope display system studying a foetus. The time -base generators and the rate are driven by electrical outputs from a series of resolvers that measure the position of the ultra- of attentuation also sonic beam as it moves across the patient Horizontal and vertical time -bases combine to deflect increases with the frequency, so we have the spot in such a way that its movement across the display corresponds to the movement of the to compromise beam. Echoes received between better as the probe moves over the patient produce a cross-sectional image in a plane resolution and reduced penetration. corresponding to that of the scan. In this example, the image is built up on the screen of an electronic storage tube for direct viewing. pulse with a large amplitude to the horizontal deflection plates to drive the Pulse -Echo Techniques transducer. Echoes return to the probe spot on the display at constant speed In an ultrasonic instrument for diagnosis, from those reflecting surfaces inside the from left to right. In this way the a probe 'containing a piezoelectric patient that lie along the ultrasonic beam sweeping across the display is transducer converts electrical signal into beam. Electrical signals from the echoes deflected vertically at intervals along the ultrasound waves for transmission into are amplified by the receiver and horizontal the patient. It axis, corresponding, in does the opposite for applied to the vertical deflection plates distance from echoes. the start of the sweep, to of the cathod-ray tube; the time -base echo -producing surfaces at various The simplest type of ultrasonic pulse - generator, which is triggered into distances along the ultrasonic beam. A echo diagnostic /system is called the A - operation by the clock at the instsnt special circuit in the receiver increases scope. (See Fig! 1). The clock triggers the ultrasonic pulse is transmitted by the amplification of the deeper echoes the transmitter, which feeds a brief the probe, is connected to the to compensate for their attentuation by

42 ELECTRONICS TODAY INTERNATIONAL - MARCH 1978 ultrasonic probe, instead of being held in the hand, is mounted on a scanner. It can be moved to any position in a two- dimensional plane. In this way it is Head of possible to arrange for the beam to pass -twin 1 through structures lying in a chosen plane within the patient, while the Head of position of the probe and the direction twin 2' of the beam are measured continuously by 'resolvers' mounted in the scanner. Placenta The electrical signals from the resolvers control two time -base generators, driving the vertical and horizontal beam tube. Abdomen - Abdomen deflection plates of a cathode-ray of twin 2 of twin 1 SAIS The direction and position of the ultrasonic beam across the patient controls I the position of the cathode-ray beam showing up on the display, related to the positions of the echo -producing surface. A cross-sectional image of the surfaces can be built up photo- graphically by a camera with an open shutter that record.; the bright spots on A two-dimensional scan (right) reveals twins at about 25 weeks of pregnancy. The placenta on the display while the patient is being abdomens of the twins, identified in the anterior wall of the uterus is clearly defined while the scanned. The echo information can also the explanatory diagram, appear in section. be stored electronically. Two-dimensional scanners in which operates In the B -scope, the time -base sweep is intervening tissues. The clock the probe is moved in contact with the' a normally invisible, but it is brightened at a repetition rate fast enough to give patient produce individual images in by returning echoes to produce spots flicker -free trace on the display. scanning times of about 10 seconds, light on the display in places where, The A -scope has clinical applications of Images can be produced at a much A -scope, there would be in neurology, ophthalmology and on an faster rate by moving the probe of the beam. The positions internal medicine. It allows the depths deflections mechanically. Images in rapid spots of light correspond to echo- of echo -producing surfaces to be of the succession allow physiological move- structures in the patient, and measured, and the characteristics of producing ments to be studied; their main be pattern of their movements can be echoes from within structures to the importance is in cardiological diagnosis. recorded. studied. permanently But although these rapid mechanical such Echoes from moving structures, scanners produce so-called real-time as the valves of the heart, oscillate in -Sectional Images images, they lack flexibility. This position along the horizontal axis, or Cross The B -scope forms the basis of another difficulty can be overcome by using time base, of the display. In cardiology display method, the two-dimensional ultrasonic probes containing many particularly, patterns of movement can ultrasonic scanner (see Fig. 3). The separate transducer elements, operated give diagnostic information. They can be studied by making recordings with the aid of a B -scope display (see Fig 2).

Stationary reflector Wave from transmitter

Reflected wave, Transmitter Receiver frequency (a) equal in to transmitted wave Reflector moving Probe towards source Wave from transmitter Receiving Transmitting Rate meter Reflected wave, transducer higher in frequency transducer (b) than transmitted wave Reflector moving away from source Wave from Recorder 4-- transmitter Í f.. Record of foetal heart wave, Reflected rate lower in frequency Ultrasonic Foetal heart than transmitted I wave beams-I The Doppler effect occurs when a wave is reflected from a moving surface, giving an foetal heart. The echoes usually fall in the range upward or downward 'shift' in frequency as in One use of the Doppler 'shift' is to monitor the (bland (c). of audible frequencies.

43 ELECTRONICS TODAY INTERNATIONAL - MARCH 1978 Doppler effect, conveniently gives Inside information shift real-time scanners and investigations from frequencies that fall in the audible range of techniques for displaying the when ultrasound is reflected by ultrasound moving. information. The ultrasonic signals from structures in the body such as heart . different tissues may be characteristic of separately or in groups, which can valves or flowing blood. A simple the tissues themselves and in some cir- produce ultrasonic scans made up of instrument based on this makes it cumstances it may be possible to parallel lines or of lines arranged in a possible to detect the movement of the identify them. Improved techniques fan shape, at frame rates of tens per foetal heart. Similar instruments to include colour -coding to demonstrate second. measure blood flow allow peripheral various tissue characteristics, and storing As well as making it possible to study arterial disease to be assessed. ultrasonic data in a three-dimensional rapidly moving structures, real-time Because Doppler shifted signals are matrix so that any two-dimensional scanners can also be used to explore received only from structures that move, plane can be selected for display. large volumes of anatomy in a short two-dimensional maps of them can be Analysis of Doppler signals from blood time. A doctor using one can examine a built up by using a Doppler probe to flow is another promising field; it may patient in about a quarter of the time it scan the patient. In this way the soon be possible to assess the effect of takes with a 'conventional' two- distribution of blood vessels close to the drugs on the cardiovascular system. dimensional scanner. surface can be studied. Such The clinical value of ultrasonic tech- The frequency of an ultrasonic wave information may be obviate the need niques has already been proved, but reflected from a stationary structure is for _ X-ray angiography, which is a their spread into general, everyday equal to that of the incident wave. If dangerous and expensive procedure. service will depend on the development the beam is reflected by a surface which It can also be combined with other of instruments that are simple to use. is moving towards the ultrasonic source, information about structure position These, paradoxically, may be more the reflected wave is compressed into a obtained by the pulse -echo method, complicated than the ones we shorter space. This means that the making it already possible to map out blood have. It will also mean training doctors wavelength is reduced. It shows as an vessels within the body and measure the and technicians to obtain and interpret upward 'shift' in its frequency. rate of blood flow at the same time. results. But it is clear that ultrasonic Reflection .by a surface moving away Work being done to improve the per- diagnosis is, in many from the source instances, the best gives a downward shift. formance of the instruments now in use and most This economical way of getting phenomenon, the well-known includes basic studies on the the information interactions essential to proper care between ultrasound and bilogical materials, the development of of the patient.

`` O r-4..;, o K .4 ,. 1- . .

414 8 CHANNEL AUDIO MIXER 485 STEREO GRAPHIC EQUALISER

8 input channels ,each with linear fader, input This superb equaliser offers 10 octave -centred linear attenuation switch, bass, treble, echo send and pan controls for each channel; level match control, in -out controls. High and low impedance PMG inputs. switch and tape monitor switch. 2 output channels with 5 stage equalisation on each channel, VU meters, overload led, master pan, echo The performance of this unit is equal to some of the and volume controls. best available. Black COMPLETE KIT $105.00 PLUS $2.50 Freight. anodised front panel with yellow lettering. Send stamped addressed envelope for specification sheet or Vinyl covered cabinet. S1.00 for complete construction manual. COMPLETE KIT $254.00 plus $5.00 Freight. P.O. Box K39 Haymarket 2000, 405 Sussex Street, SYDNEY. jaca Tel: 2115077.

44 ELECTRONICS TODAY INTERNATIONAL - MARCH 1978 NOBODY CAN BEAT FAIRCHILD AT THE NUMBERS GAME. Fairchild's Optoelectronics Division builds more LED digits than anybody else. Bigger digits than anybody else. Brighter digits than anybody else. And we can n even fit more character , size in a smaller package than anybody else. In short, we know digits. Our digits are available With oy pins or as PC board mounted stackables. And, you get a choice of common anode or I common cathode varieties. í Our digits also come in the widest selection of colors available. Red. Super Red. Orange. Green. ."0\ A WORD ABOUT DIGIT TECHNOLOGY. r;r;94 4 Our patented light pipe construction yields /` /;k the industry s most efficient LED display. Y The result: A bigger, brighter digit. Lower cost. ' / /¡/ Lower voltage requirement. A way to outspec j ' your competition. 1.`/ / LET THERE BE LIGHT. // Whatever your digital display need- industrial, consumer or automotive, you should light up our switchboard first. Because with high volume production of digits, LED lamps, phototrarisistors, couplers, arrays and LED dice, nobody has more experience or better technology than Fairchild.

Contact your nearest Fairchild distributor

NSW: George Brown, 519 5855 Amtron Tyree, 698 9666 VIC: Browntronics, 419 3992 FAIRCHILD Amtron Tyree, 288 7099 Warburton Franki, 699 4999

WA: Warburton Frank i, 65 7000 SA: Protronics, 51 4713 lingo OLD: Warburton Franki, 52 7255. «SE? " w to get the sound of a whole new hí -fi. system for around X35

Are you sure of the quality of your loudspeakers? Most people can't afford top quality speakers at first. So they upgrade the speakers later. If you're at that stage, you will know you're not going to do it for less than $200-$300 - not meaningfully. We offer an alternative. The Elcoma kit below gives you two Philips dome tweeters, cross -over capacitors and complete instructions to extend the frequency response of your existing speakers to 20kHz and beyond. (For non -technical readers, that is well beyond the range of normal human hearing). And they do it with excellent transient response and low distortion. (That means the highs are crisp and clear without grating). The dome construction disperses the high sounds naturally all round the room - not in a narrow beam like a flashlight. (Ordinary tweeters can do that). You can work this miracle on your stereo system in about ten minutes. For around $35. Why not try it before you write a cheque for $300?

PHILIPS ELECTRONIC COMPONENTS Complete instructions AND MATERIALS printed on pack. Sydney 427 0888 Melbourne 699 0300 Brisbane 44 2471 Adelaide 223 4022 Perth 277 4199

PHIGIPS Electronic Components and Materials PHILIPS

BA.EL2 Project 588

THEATRICAL LIGHTING CONTROLLER

''1 Pt.4 Final Details

THIS MONTH WE FINALISE the series on dimmers with the mechanical description of the control desk. Although the mechanical drawings of the rack are too large and complex to reproduce here, and some ..---- parts, like the 20A 2441. « 5 edge connector, are specially made, we T7 SI have made arrangements with Nebula . _. . ' Electronics Pty. Ltd. to supply these items. If the dimmer modules are not required to be connected through sockets, the total cost can be reduced MUM by connecting directly to the modules and mounting them in a box. In the 20A unit the heavy wires, should be bolted on to the appropriate pads to ensure contact to both sides of the board. One modification we have made to the control desk is the addition of a a black -out switch which allows all lights to be blacked out without moving the master control. This is simply done by switching the supply voltage on the master potentiometers from the -8V supply as set by RV3 to 0V. RV3 should be adjusted such that with one master at maximum, the sec- If the dimmer is connected up to When adjusting the maximum and ond at minimum and one individual a reasonably heavy load and adjusted minimum levels the minimum should be control at maximum that its output for about 1/3 level it will probably adjusted first. Note that the control voltage should be + 10 volts. be found that with RV3 at one end the potentiometer must be slightly up With the dimmer module the trim light level is not stable and tends to off zero to get any light and minimum potentiometer has to be adjusted so flash. This is caused by the sync pulse should be adjusted at this point. The that the output pulse from IC7 occurs occuring after the end of the half cyc- maximum should be adjusted with both at the very end of each half cycle as le and the trigger pulses from the prev- the master and individual control at shown in Fig. 3 (page 69, Dec 77). ious half cycle triggering the next. The maximum and set to the point where This is easiest set using an oscilloscope trim potentiometer RV3 should be the light level is just starting to drop. although an approximate setting can turned back about '/ turn from the be made without one. position at which this effect stops.

ELECTRONICS TODAY INTERNATIONAL - MARCH 1978 47 Project. . ~~~ ~~~

Theatrical Lighting Controller nebula Electronics Pty. Ltd.

- r - - - - ° r lo ° ` ° ° / ` 10 10 _-,-_ __,__ ^__ _-,__ ,__ __,__.-_,_- __,_- __"__

^__ ^__ __^__ __"_- _-.__ _-^__ __^-_ __^__ __^__ __`__ ,_- _-^__ __,__ ,_--_ __"__ __"-_ 2 ,_- __"__ __,__ __"__ ,__ | .---_ ,--__

MASTER 1 2 3 4 5 6 7 8 9 10

r ° 10 ° ° 10 "* _-^-_ "' ,'

5' 4' , "__ 2 ,__ .-_

Fig. 1. The front panel artwork for the 10 way control desk. Full size is 440 mm x 250 mm.

930 60 ~

-l-

| .9-290 80

Fig. 3. The control desk box dimension

48 ELECTRONICS TODAY INTERNATIONAL - MARCH 1978 40 80-6. 10P..í 130 -44 160-- 190- 220 250 280-w 310 340 370-'. 400 440

NOTES:

Q 2 HOLES 6.4mm DIA.

O 4 HOLES 3.5mm DIA. 22 SLOTS 66mm 3mm S MATERIAL: 1.6mm ALUM. O- SATIN ANODISED Fig. 2. The mechanical dimensions for the front panel.

80 130 -y

26+ 65+ 85 .1 r- 1154. 145 175-+ 205-r 235-r 1265-4.295--r 325- 355-+ m -- e- I --O.-- 0-$- 0----0- - -- ____I. l_._o a - e-- _li ---1- -- e----e=--=_ r 1 o-- e--(3- e-- e s- o ! l o s NOTES:

O2 HOLES 19mm DIA. E R O 56 HOLES 3.5mm DIA. - o O -i_ i. L I 9 _Q-O --0--e--e--e- -@----- 22 SLOTS 66mm 3mm ®- o MATERIAL: 1mm STEEL. PLATED Fig. 5. The potentiometer support panel.

L1n nl THEATRICAL LIGHT DIMMER The following components for these dimmers are available from Nebula Electronics, 15 Boundary St. 1 Rushcutters Bay 2011. BTW41-400 TRIAC S 9.50 7? 10A or 20A choke S 10.50 20A Amptrap fuse S 2.50 748 20A Amptrap fuse clips S 0.80 Philips 4322-020-36630 core S 0.65 20A PCB S 13.00 10A PCB S 11.00 10A Module (complete kit) S60.00 20A Module (complete kit) S 69.00 10 Way control desk S 125.00 20 Way control desk S 195.00 Prices of other components available on request. Add 15% sales tax, 5% postage 248 NEBULA ELECTRONICS PTY LTD. Fig. 4. The end pieces for the box. These should be fitted 15 BOUNDARY STREET into the ends of the box as shown in Fig. 3. The two ends RUSHCUTTERS BAY 2011 should be of opposite hands. ph. 335850

ELECTRONICS TODAY INTERNATIONAL - MARCH 1978 49 r pu ter Corn Products

1978 CATALOG NOW AVAILABLE SOROC 10120 A CAPABLE LOW CriC/./l!!lllllllllJlJlJtllll!-/,/l./1..á COST, APPROACH TO $975.00 REMOTE VIDEO 8K STATIC RAM BOARD TERMINAL DISPLAY TERMINALS Assembled ASSEMBLED AND TESTED

$ 975.00 Assembled $189.95 Key Standard 250ns. Curio, Comrol Numeric Key Pad Standard Line and Page Erase Standard Price Includes Addressable Cursor Standard 4 50ns. $150.00 Sellen Selectable Tranemiselon Block Mode WILL WORK WITH NO FRONT PANEL Irdm 75 to 11.200 boa Slenderd * Communkarbn Mode Lower Case * FULL DOCUMENTATION HDX COX Bbol 24 Option 11/1 Interlaces Punter Interlace Line * FULLY BUFFERED 652.17E+1enabn and shipping * SIOO DESIGN sr.:,:v:l:r.'.1:s'fir,i QS 1? RS232C interlace Non4lre Read Out Screen charge Is on us. * ADEQUATELY BYPASSED Protect Mode Standard * LOW POWER SCHOTTKY SUPPORT IC S Tao Standard KIT THE PROM SETTER JADE VIDEO INTERFACE KIT 250ns. $169.95 WRITE and READ FEATURES EPROM $89.95 450ns. $129.95 1702A-2708-2716 S-100 Bus Compatible 32 or 64 Characters per line BARE BOARD $25.00 5204-6834 16 lines W/SCHEMATIC Computer raphics (128 x 48 matrix) Plugs Directly Into your ALTAIR/IMSAI Parallel & Compositive video ADAPT YOUR MOTOROLA 8800 Includes Main Module Board and External EPROM On board low -power memory SYSTEM TO OUR S-100 8K RAM Socket Unit is connecte to the Com- Powerful softw a included for BOARD, KIT PRICE $12.95 The EPROM Socket Unit Scroll Graphics/ puter through a 25 Pin Connector home, ELL, Cursor,haracter, etc. Programming is accomplished by the Computer C Upper case lower case & Greek IMSAI/ALTAIR S-100 COMPATIBLE lust Read in the Program to be Written on the Black -on -white & white -on -black EPROM into your Processor and let the Computer do the rest into Use Socket Unit to Read EPROM's Contents JADE your Computer MOTHER BOARD BOARD w/front included 13 SLOT MOTHER Z80 Software panel slot -with PROVISIONS for Computer does KIT IVo External Power Supplies, Your S-100 DESIGN it all FULL GROUND PLANE ON ONE SIDE ONBOARD 2708 and POWER ON JUMP Doubles as an Eight Bit Parallel I/O RC NETWORK TERMINATION ON PWR & GRD (2MHZ) Manual included EVERY LINE EXCEPT KLUGE AREA $135.00 EA THE PROM SETTER STRONG 1/8" THICK DOUBLE SIDED KIT ASSEMBLED BOARD (4MHZ) $210.00 $375.00 BARE BOARD $35.00 KIT $85.00 $149.95 EA FOR S-100 JADE PARALLEL/SERIAL PERSCI DISK DRIVE BARE BOARD $35.00 INTERFACE KIT COMPLETE KIT DISK SYSTEM s -too $124.95 Info 2000 S-100 2 Serial Interfaces with RS232 (includes dual drive, power supply, case, and JADE 8080A KIT interfaces or 1 Kansas City cassette intelligent controller, adapter, cables, interface. disk monitor on EPROM) $2,650.00 Serial interfaces are crystal controlled. KIT Selectable baud rates. COMPLETE TDL SOFTWARE $100.00 Cassette works up to 1200 baud. PKG. FOR DISK $195.00 1 parallel port. BARE BOARD $35.00

MICROCOMPUTER MISC. PROM'S OTHER COMPONENTS MICROPROCESSOR', 8080A SUPPORT DEVICES CHARACTER 17070 500 te I 70 INTERFACE 8712 395 GENERATORS 5/10025C VIDEO F B 19 95 nod 1500 250 8214 995 6 75 1300 NH0076CN Tu-] Z80 7500 7513 UP 2708 581 20 350 8216 a50 6 75 38 TV -1 Video Z800 3500 2513 DOWN 2716 00 N8T76 2 45 You will want to know about the 6224 495 15.1 9 95 450 CDP18020D 2495 2513 UP 3601 74367 90 Interface Kit. 8228 8 75 10 95 400 to Televisior AM 7901 77 95 2513 DOWNIS.1 570.300 DM8098 90 8238 800 MC M6571 10 80 No need to buy a separate Video Monitor if 6502 12 95 570900 600 1488 195 8251 1700 MCM6571A 10130 16 95 the 6800 19 95 6834 1489 195 you already own a TV set. Just connect 75 8253 78 00 10 80 1 14 1 MCM6572 8008 B 6834 95 D.3707A 2.00 between system video output and 80808 1595 8755 1700 MCM8574 14 75 825238 400 TV1 your C 3404 395 - that's all there TM5990oTL 8995 8257 2500 MCM65e5 54 75 87718 2 70 the TV set antenna terminals 8159 7500 P 3408A 500 set a Video P4201 4.95 is to it - to convert your TV to 6800 SUPPORT DYNAMIC RAMS MM 5370 750 Monitor, and at a much lower cost! PRICE $8.95 100 1 90 6810P 4 9 STATIC RAMS 1.2 25.99 1103 1 50 MM 5369 1 8)30 290 6870P 800 71107 14501 1 SO t 40 75 7104 450 DM 11 1 2 75 6076P 25 71107 12501 1 95 r 90 50 21070 175 DM8131 6834P 1695 21111 425 410 395 71078 450 OM 8831 250 6850P 9 95 IOtA 49 179 110 210784 900 OM 8833 750 6857P 1195 71011 295 775 760 TM54050 4 50 13618835 250 6860P 1495 2107 125 115 100 7M54060 4 so SN74LS367 90 1795 I 30 115 4096 450 SN74LS368 90 Products 6862P 2'02 1 I50 Computer 6880P 7 70 400 350 325 4116 4200 71111 KIM 71121 300 280 269 MM5270 500 5351 WEST 144th STREET 16.95 1650 MM5280 600 280 SUPPORT DEVICES 2114 1795 KIM 1 245 00 17 95 12 50 11 95 MCM6605 600 6502 1795 LAWNDALE, CALIFORNIA 90260 3881 17 95 4700A E 1195 1175 7075 6520 900 3882 1295 5101C (213) 679-3313 UART'S 6571 9 25 550 WAVEFORM GENERATOR KEYBOARD CHIPS 495t0130 6530-002 15 95 Discounts available at OEM Quantities. All prices above are quoted in US F.e SUPPORT DEVICES 13 95 95 10140 895 15 95 Avb.2376 6530-003 L shipments please include interne - 8038 400 TR.16020 5 50 SF.0.8. awndale, Calif. USA. To expelkiale .1851 14 95 415 3600 13 95 6530 004 15 95 MC4074 750 Donal money order or bankers check payable against any USA hankie USS, or 3853 14 95 TM56011 695 6530-005 15 95 566 ' I t5 IM 6902 10 80 affiliated credit cards of Bank Amena or Master Charge welcome (Include LATE ADDITIONS FLO PV DISC CONTROLLER IM 6903 10 80 USRT card No., expiration date and signature).. Add 10 percent of total order for 1771 5595 4044 $14,00 5 7350 10 95 postage. For orders less Man $10 add 1.50 service charge. TMS 1 771 TM5 5501' 524.95 01 59 95 / WIREWRAP

PRECUT WIRE WIRE WRAP SOCKETS 167 25-99 1 W- 5 250-999 1K=5K Why buy wire on rolls? 1± e pin 41 38 35 31 29 .27 39 39 32 32 PRECUT 8 STRIPPED 1a 30 WIRE IS: p"a2 43 39 35 32 30 e pm 46 BURGLAR Fast - No more cutting & stripping by hand 11pmn 63 511 54 47 44 .41 20 84 78 11 63 59 .54 Reliable - Good, clean, uniform strip pen 130 120 110 95 90 M Economical - Cheaper than using bulk wire rip" 24 pm 91 64 78 68 64 59 Precu Wire Bulk Wire 26 pin 125 115 I08 95 69 92 - 40 pin 165 1 55 1 42 1 25 1 15 1 09 ALARMS 100 p:s O1 3. at ]wile, 50 h von at S1 99 44/R 682 GOId J-lere. Closed Entry Sockee 100 pica 100 h et 295 %/K.End '91. " 1 C.' - 29'8. r" 6 Side Suckable Ali prices Include gold Wire Kil 1 166 95 = 2 1/]ve T. sockets aM 2 -tare. sockets wallet. WE STOCK: Alarm Modules, Electronic Eyes, Photo Sensitive Cells, Micro- 30 Kyna, napped r on own end Lengths an orere.t WIRE WRAP TOOLS Colors 4163.13I0e Green:feu...-Black Orange While waves, Ultra Sonics, Gas/Heat/Smoke. Sensors, Sirens, Bells, Wire ~aged in plastic bags Add 25t/length for tubes Pressure Mats, Door Monitors, Car/Caravan/Home/Office Hold 109 SOO loon 5999 s 2.1 in 78 240 4 ]N1( 36WK Up Factory Alarms, Key Switches, Reed Switches, Relays, 3 I 62 260 471/1( 22/K Shock Recorders, Aluminium Tape. You Name It. We Have 3S In 86 260 512K 455/K It. 4 in 90 300 55óK 4806

4.51n 94 321 59310 521/K 5 in 96 342 63416 552,0 r DO YOURSELF IT PRE -WIRED SYSTEMS 5.1m 102 365 675,6 58áK $34.95 - 6 In 106 365 716K 6191K HOBBY WRAP EASY INSTALLATION 6'1 in 11S 405 757/K e52/K Model BW 630 7 In 120 425 7911/K 665111 rime 125 445 II 3911( 7 184 With Free Wire Kitt PORTABLE ALARMS e me 129 465 86VK 75L( (5695 Value) r) en 132 485 921/K 7 64r Microwave Systems concealed in Hi -Fi Speaker Enclosures or Batteries & Charger 511.00 9 m 136 505 962/0 a mg Desk Mains Operated, Self -Resetting 9Y in 140 525 10030 950,6 WSU 30 Hand Wrap -Unwrap Strip Tool 5.95 Units, Fully Automatic, 10 in 145 5 St 104468 863/K WSU 30M. for Modified Wrap 6.95 with battery standby. 60ds in to 41 e2K 69K BT 30 Extra Bit 2.95 Send 80c in Stamps for Illustrated Catalogue. WIRE KITS INTERCONNECT CABLES Ribbon cable connectors tor connecting boards to Pont pen.h or board to board N.S.W. AGENT FOR NIDAC SOLID STATE . 1 fa 95 a 2 911.95 SECURITY SYSTEMS SINGLE ENDED DOUBLE ENDED 250 3 tpp 4 , 250 I) 750 4 , 250 6 250 3 - 100 S 500 3 250 5- ton 6 tape 16 pin 24 pin 14 pin 16 pin 24 100 4 100 6 500 3 - 100 5 100 7 6 t >t 2 OS 2 45 376 500 4 12508 Ron Bulk 1e. 2e. ] 17 133 144 224 231 255 392 WHOLESALE SECURITY FROM 1 76 a 31 Choose One Color 24 52 l 65 263 2 52 2 I 91 206 291 317 506 or Assortment 46 340 PROTECTOR PAGE DIGITAL GdOrdering$25,, add62Btl°n. PayabInclude'ycashi0%Ice shipping Payable by usherscashiers In R.C. ALARMS ELECTRONICS Us. Funds 135 E. Chestnut Street 4A Visa and Master ChargeA

IF YOU ARE THIN KING ABOUT A TMS 9900 PIN ASSIGNMENTS 64 HOLD MICROCO VIPUTERVBB VCC 1--2 63 MEMEN L.,: 62 START HERE! LIAR 4 61 WE MOLDA 5 x-.60 CRUCLK WHAT DO YOU NEED FOR A TOP RESET 6 59 VCC QUALITY MICRO COMPUTER? IAO 7 58 NC 157 NC 1. YOU NEED THE RIGHT MICROPROCESSOR o1 B o2 9 . 56 015 May we draw your attention to the features of the easy to Intertac e with slow memories e Advanced Ala to :` .55 014 TMS9900: a Texas Instruments 54 -pin NMOS mic- memory -to -me mory architecture 16 General Pur- 11 roprocessor chip (CPU) e 16-bit Instruction Word, pose registers er file e Separate Memory, 1/0 and 0.13 54 013 and 8, 16 and 32 bit operation e Full minicomputer Interrupt Bus Jtructures a Separate Address and Al2 12 53 012 instruction set with 69 instructions a Hardware mul- Data Bus Struct acres no multiplexing Multiple - All 13 52 011 dply and divide, with 32 -bit capability a Bidirectional workspace regi ster files in memory And 16 user - parallel 16 -bit data bus a Parallel 15-bit address bus defined extends d operation instructions. A10 14 51 D10 directly addresses 64K bytes e 3.3 MHz Clock but - A9 15 Í ' 50 D9 No other microprocessor In the world has this range of features AB 16 Ws, 49 D8 A7 17 48 D7 I 2. YOU NEED THE RIGHT CPU B )ARD FOR IT A6 18 ; 47 D6 A5 19 1 46 D5 The TECHNICO T -9900 -SS board is a masterpiece of design. It is a Stand - alone System. This means that it is a r microcomputer on its own (just connect your terminal and power supply). Other boards and peripherals can be AA 20 45 D4 added, to build a minicomputer of any size and configuration. And it is bull t around the TMS9900 microproces- A3 21 44 D3 sor. . A2 22 W. 43 D2 May we tell you more? Send your name and address to: Al 23 El» 42 01 AO 24 el 41 DO I.M.P.A.C.T. LTD., P.O. Box 177, PETERSHAM 2 )49 (560-7503 A.H,) 04 25 ter 40 vas Vss 26 f 39 NC Please tell me more about the T -9900 -SS Microcomp uter. I VDD 27 r 38 NC I o3 28 37 NC 1 NAME I 0B1N 29 11111» 36 ICO I CRUOUT 30 35 IC1 ADDRESS 1 f I CRUIN 31 «MI f 34 1C2 STATE POSTCODE I INTREO 32 4.1 33 IC3 L

ELECTRONICS TODAY INTERNATIONAL - MARCH 1978 51

r ETI's COMPUTER SECTION ...... More on Z8, Z8000 Zilog have released more information on rr the Z8 single chip microcomputer. rar..irna: Featuring 130 instruction combinations -'. (against the Z80's 158), the Z8 runs at - 41, o 4 MHz and packs 144 registers, four im.n.t T. . 8 -bit I/O ports, 2 Kbytes of ROM and .; 128 bytes of RAM onto the chip, as well as two counter/timers, four hand- . - .. shaking lines, and a UART (not two - pins attached to the accumulator, but . a genuine UART). The Z8 can also ... ..b. x,: u- -141 address another 62 Kbytes externally. How it gets all that I/O, control, address and data signals through 40 pins is a mystery yet to be revealed. n_k3.1ciUra`L .. The Z8000 16 -brit microprocessor lies at the top end of the market. Addressing up to 8 Mbytes directly, the Z8000 can be teamed up with a matching memory management chip which will provide relocation and memory protection. Its .J.tuJil.íUurwtllil.iu"wwr.Ww.WWWrWrw,,1 418 instructions include 16 -bit multiply and divide, as well as powerful string manipulation functions. All 16 16 -bit 2708 Programmer registers can be used as accumulators, Pennywise Peripherals have just released EPROM plugs into a zero insertion force and all but one can be index registers. an economical PROM programmer for socket and a write disable switch Among its other tricks is the ability to 2708 EPROMs. protects the EPROM from accidental handle 32 -bit words, plus all the usual The programmer is built on a single programming. The supply voltages trap and interrupt handling. Since the printed circuit board which plugs required are +5, +12 and -12. All others Z8000 is bus -compatible with the Z8, it directly into the motorola bus. Due to are generated on board. can use that micro as a general-purpose its novel design, the programmer is peripheral controller. No pricing info particularly easy to use. It looks, to yet, but I'll bet a lot of computer the microprocessor, just like ordinary NEC 64 K RAM hobbyists are preparing to hock them- memory. Reading simply reads out of Nippon Electric Company are in the selves to the eyeballs! PROM. Writing feeds the data to the process of shrinking a two -level poly - addressed location in the EPROM and silicon 64 K dynamic RAM to a size 32K EPROMs Emerge applies a programming pulse; the correct that will make economic volume Texas Instruments production have started sampling setup and hold times are automatically feasible. Release is tentatively 32K EPROMs in 24 -pin scheduled a package, inserted and a busy flag indicates when for 1979 of two versions: one type number 2532, and have sparked a 64 K by 1 version pulsing of the location has been in a 16 -pin pack and off a debate in the industry regarding the other a 22 completed. -pin 16 K by 4. standard pinouts. Intel are apparently Thus to program an EPROM the proceeding with a different pinout on microprocessor simply block moves Blowing Bubbles Smaller their 2732, although both were on the data to it from RAM or another IBM is reported to have fabricated a JEDEC committee to standardise 32K EPROM. bubble memory which is up to an order EPROM pinouts. Intel claim their pinout The programmer allows the EPROM of magnitude denser than previous is more compatible with upcoming be to test read at any time during devices. Their 1 K experimental chip microprocessors. We'll just have to wait programming. Also, a program can be uses the magnetic bubble lattice and see which part becomes the executed from an EPROM when concept - this is the first time it has industry standard. Early indications are plugged into the programmer. The been tested in a working device. that it will be the TI part.

52 ELECTRONICS TODAY INTERNATIONAL - MARCH 1978 CRT Controller IC Fifth away from the start in the great CRT controller race, National Semi- conductor is powering up the straight 7 with the DP8350, now being sampled ' s to customers in the US and Europe. According National, A to the device is unique in having an on -chip crystal - controlled clock oscillator and on -chip character generator. iCOM Attache 10 < iCOM, a division of Pertec Computer Corp., who own MITS (remember MITS?), have announced a new desktop personal computer. The Attache looks remarkably like a Sol built into a fibreglass attache case, and is S100 based. More details as soon as we get them.

Tape Reader, Number Cruncher COMPUTER Two new gadgets from S M Electronics CLUB DIRECTORY of Box 19, Doncaster East, Vic 3109, Sydney: Microcomputer Enthusiasts (03) 842 3950 will be of particular Group, P.O. Box 3, St. Leonards, interest to readers of this column. Their 2065. Meets at WIA Hall, 14. high speed paper tape reader is of the Atchison St., St. Leonards on the 1st 'pull -through -and variety, -run' which Kit, which puts a National Semicon- and 3rd Mondays of the month. interfaces to an 8 -bit parallel port. ductor MM57109 Number Cruncher IC Melbourne: Microcomputer Club of Supplied with 8080 or 6800 software, onto a PCB along with the necessary Melbourne, meets at the Model the tape reader uses available light interface electronics to get it to work Railways Hall, opposite Glen Iris shining through the tape holes to drive a with a micro. The kit is supplied Railway Station on the third Satur- sensor array. Correct operation is complete with an Application Note and day of the month at 2 p.m. monitored by 4 status LEDs and inter- Data Notes, so that the user knows how Canberra: MICSIG, P.O. Box facing is through a flat cable and plug to use it, and assembly loóks darn near 118, Mawson, ACT 2607 or contact which are supplied with the unit. Kit fool -proof. The edge connector is a 24 - Peter Harris on 72 2237. Meets price is $75.00 and assembled it's $95.00, pin type, which fits no computer bus at Building post free in Australia. Handy when that we've ever heard of, but it should 9 of CCAE, 2nd Tuesday of month at 7.30 dealing with people who supply software work with most processors with only p.m. Newcastle: on paper tape, whereas you use CUTS. slight modifications, if any. So if you contact Peter Moylan, The other new goody from S M want to do some decimal arithmetic, Dept. of Electrical Engineering, Electronics is their Number Cruncher here's the board you want. University of Newcastle, NSW 2308. (049) 68-5256 (work), (049) 52- 3267 (home). Brisbane: contact Norman Wilson, VK4NP, P.O. Box 81, Albion, Queensland, 4010. Tel. 262 1351. New England: New England Com- puter Club, c/- Union, University of New England, Armidale, NSW 2351. (New club; not restricted to students) Auckland: Auckland Computer Club, P.O. Box 27206, Auckland, N.Z. Computer clubs are an excellent way of meeting people with the same interests and discovering the kind 110111.11111111111111111111111 of problems they've encountered in getting systems 'on the air'. In addition, some clubs run hardware and software courses, and may own . . . . some equipment for the use of v f ;11, '11P M. 71. members. Try one - you'll like it! . 77;o77'1. ;".- If your club is not listed here, please drop us a line, and we'll list you. The same applies if you are interested in starting a club in your area. Also, if established clubs know their programme of forth- coming events, we can publicise them.

ELECTRONICS TODAY INTERNATIONAL - MARCH 1978 53 n

Radio Shack TRS-80 Book Reviews -I Probably the big news this month as far This month we look at two books and a , as Print Out is concerned is the magazine, which were supplied by Australian release of the Radio Shack Computerland, 55.Clarence St, Sydney. TRS-80 microcomputer, which will be So if you want to buy them, now you marketed through Tandy stores. We'll know where to go. rRF.A'lC-gULDG[NdPIITRJI YRODRAMMINO IN bé bringing you a full, in-depth report in .1R.1tR.t.11V1.1.1P.i111 the next issue (we'll also have some good Your Home Computer, by James White, , stuff on PET 2001), but meanwhile, Dymax, $9.95. This book is aimed at the here's some info on TRS-80, based on computer tyro - the person who knows initial impressions after a few days' use. nothing about home computers, but has Fur the Rabbit.. Ntudtt. "I .t Better than we expected. The TRS-80 seen one and is very curious, perhaps Cumple.t Nnvho. U.ru n' tew.tt..mR..d AI.rAIR isn't a hobby computer, (although an even wanting to buy one already. After ltyt B -A N -I.0 ut.d t . perwua.l c.m.p.dun - and the S100 adapter will be available later in reading Your Home Computer, even the similarilr DEC BASIC-PIES -_, , . rt- a most sceptical will be converted - it's the year), it's home computer, and so BY is quite docile and tame. The 4K BASIC the kind of book that's filled with JRRAIA R. BROWN supplied in ROM is surprisingly powerful infectious enthusiasm. (this may be due to the compactness of The approach the book takes is 1t'y11t1r.^t r 'Y' t _ora~1'^,rbe- . Z-80 code) and includes a pretty full almost totally non -technical, although it complement of BASIC commands, does discuss microprocesoors in functions and statements. String considerable detail and introduces terms provides the answer, in the form of an handling is a bit weak, with only two like RAM and ROM before really intr- 'active participation' workbook, which string variables, AS and B$ (just enough ducing the home computer proper. The will take you from scratch right up to to hold two names for a game). In add- hardware describer is mainly oriented to subscripted variables, arrays and sub- ition, I'm darned if I can get 'IF A$ = the American market, but is discussed in routines with no pain. 'YES' THEN 50' - type statements to general terms, and many of the units are The style of this book is virtually work! now available in Australia. indescribable, a kind of Whole Earth/ On the other hand, it does have There is very little on the subject of Cole's Funny Picture Book / People's DATA statements, GOSUB, ON N software, but there are plenty of other Computer Company / What to Do After GOTO, PRINT AT, TAB, INT, ABS, books on the subject, and in any case, a You Hit Return mixture. This is used to RND, a bunch of relational operation computer is a necessity when learning good effect with all kind os crazy and logical operators. A number of programming, whereas most readers of graphics which exhort the reader to graphic statements are also included to this book will not yet own one. 'READ' when he should read, and set or reset a graphics location on the The book really comes alive for me 'DO IT' when he should attempt an screen or to test its status (on or off). towards the end, where Mr. White starts example. And do it he must - this book All in all,it's quite good for a 4K BASIC, to discuss various applications for home is designed to be used with a computer. though it doesn't offer the same facilities computers, including games, fine arts, There are lots of little program examples as more advanced BASIC's, obviously. education, amateur radio, robots, to try out. The User's Manual seems pretty good, electric trains, financial record keeping, Most BASICs come with a manual, written in a light, humorous style. If stock market analysis, home environ- and some are very good for beginners, you already know BASIC, it's a bit meet control and many more. Once but if you haven't got a manual, or it's difficult to be patient with all the short you've got your computer, and are not very good, or you're just interested, examples, though. Anyway, a full report wondering what to do with it, this is Instant BASIC gives good value. of what we discovered will follow next just the kind of stimulus that will make Calculators/Computers Magazine, edited month. In the meantime, for anyone you a computer user, and not a by Don lhman, Dymax, $4.50 per copy. who's already got a TRS-80 and is computer builder. looking for a user's group, try sending a The book finishes with lists of useful Dedicated to the application of self-addressed envelope and IRC (Inter- (US) addresses, including periodicals, calculators and computers in the class- national Reply Coupon) to: R Gordon clubs and computer stores. If you are room, this magazine is aimed mainly at Lloyd, 7554 Southgate Road, Fayette- titillated by home computing, but not teachers, although a large proportion of ville, NC 28304, USA, who is (we hear) yet galvanised into action, this is the it is suitable for duplication and classes. The style is rather forming a group in the US. Don't know book to do it. Highly recommended for distribution to of anyone in Australia yet, perhaps the beginner. like 'Instant BASIC', with lots of graphic will let us know if something's brewing? designs and large arrows saying 'COPY ME'. Amongst the articles in Vol. 1, Instant Freeze-dried Computer No. 2 are ones on classroom computer Programming in BASIC, by Jerald R. games, introducing calculators -to junior Brown, Dymax. Subtitled: For the school classes, Simpson's rule on a hand Hobbyist, Student, of Compleat Novice. calculator, the computer game UPS, Learn the NEW streamlined ALTAIR BASIC subscripted variables, teaching style BASIC used in personal computers using computers and PET. and the similar DEC BASIC PLUS. Although the slant is mainly to edu- Well, you've bought your computer, cation, Calculators/Computers is well some RAM, tape interface, terminal and worth having for the computer games now you've got a BASIC interpreter. alone. Teachers and educators just can't Where do you go from here? This book afford to be without it.

54 ELECTRONICS TODAY INTERNATIONAL - MARCH 1978 No computer magazine gives algorithms, you more applications than we do! shuffling and string IF YOU'RE NOT manipulation to make your own Games. Puzzles. Sports simula- programming tions. CAI. Computer art. Artifi- easier and moreeffi- cial intelligence. Needlepoint. SUBSCRIBING TO cient. Music We can even save you time and and speech synthesis. money. Our extensive resource Investment analysis. You name it. creative comp xtin section is filled with We've got it. And that's just the all kinds of beginning! facts plus evaluations of hundreds YOU'RE NOT of items. Including microcompu- Whatever your access to computers, terminals, ter power-home computer kit, peripherals, soft- mini, ware packages, periodicals, book- time-sharing terminal-Cre- GETTING THE MOST lets and dealers. We also ative Computing is on your wave- give you length. Whatever no-nonsense equipment profiles to your computer OUT OF help you decide which computer is application-recreation, educa- best for you-before you spend tion, business, household manage- money ment, even YOUR COMPUTER. on one that isn't. building control-Cre- We ve got fiction too. From the ative Computing speaks your best language. authors in the field, like Read Asimov, Pohl and Clarke. Plus through pages of thorough- timely reviews of computer books, ly documented programs with vendor manuals and complete listings and sample runs. government All made easy pamphlets. And so much more! for you to use. Learn Isn't it about time you subscrib- about everything from new soft- ed to Creative ware to microprocessors to Computing? It's new uses for the smart way to get the most home com- ;+ out óf your computer. puters. And all in simple, understandable terms. Complete this coupon and mail it today.° r for fast And t here's st ill more. response,call our toll - CreativeComputing free hot line. discusses creative. N programming tech- (800) 631.8112.(In niques like sort New Jersey call (201) 540-0445).

s.r:.

b' r ' 1 Please supply Nil wish the 55 Clarence Street, Sydney, following subscriptions ELEcIROniC conc'c?zs PIu LID NSW 2000. Phone: 29-3753 r1 CHEQUE MONEY ORDER ENCLOSED CHARGE MY BANKCARD Magazine f 1%1 Year Subscription *Air Mall creative TOTAL REMITTANCE $ Please computing - 12 Issues $46.00 send 10: Byte .,;.12 Issues $46.00 Dr Dobbs `r 10 Issues $21.00 Name Interface Age 12 issues $45.00 P.P.C. _6 or more $18.00 Address. Personal uting 12 issues $43.40 n ROM 12 Issues $46.00 City ' State P.C. Calculators and Computers 012 issues $45.00 BANKCARD CLCCLROnlc concCKi KV LID * Due to constant delays relative to ocean Acc. No. freights, and keeping In mind the fast moving Showroom & Offices developments In the micro Industry we decided Expiry Date computer Ground Floor to airfrelght all magazines to offer you fastest possible service. 55 Clarence St, Signature IAAv SYDNEY NSW 2000 ...... I Extra M6800 Instructions are potentially quite useful. For the benefit of 6800 users the 55 This useful hint was sent to us by David In particular, a number of additional 'unimplemented' op -codes and their Craig of Holland Park, Brisbane. All you test instructions form a useful definitions are listed below. All the op - 6800 users out there can have hours of supplememt to the Bit Test and Test codes are in hexadecimal. fun trying these out! Zero or Minus instructions of the 6800. The Motorola M6800 provides 72 For example, the op -code 45 which A. Actual invalid op -codes: 3C, 3D, DD, a of the executable instructions. These require performs test logical right shift 9D - stops processor operation, reset 197 different op -codes when all the A accumulator can be used to test required to regain control. allowable addressing modes for each whether the contents of A are odd or instruction are taken into account. To even by examining the carry bit (C) B. Alternative op -codes for existing number of op -codes the after executing the test instruction. The provide this defined operations:. 6800 uses an 8 -bit word length which test instructions perform the operation NOP 00, 02, 03, 04, 05, 38, 4E, 5E can specify two to the eighth (i.e. 256) on the data in the nominated registers DAA 18 op -codes. Motorola's literature says that and alter the condition codes TBA 1E only 197 are valid, and that the other accordingly, but leave the original BCS 21 But are they? registers unchanged. 59 are 'unimplemented'. COMA 42 The answer to this question is a The op -codes 14 and 1A which COMB 52 no! It appears that only four provide the logical AND and OR definite COM 62 (Indexed), 72 (Extended) of the 59 op -codes that Motorola does respectively of accumulators A and B NEG 61 71 (Extended) invalid. The should also prove useful. (Indexed), not define are actually LSR 65 (Indexed), 75 (Extended) are executed quite happily by It is doubtful that most of the other other 55 CPX EC (Indexed), DC (Direct), 6800 and well defined extra instructions are particularly useful, the produce CC (Immediate), results. 26 op -codes simply though in certain circumstances they of these FC (Extended) codes could find use in saving an instruction provide alternative for already BSR CD The remaining 29 or two. The group of op -codes 87, C7, defined operations. JSR ED (Indexed), FD (Extended) provide operations which have not been 8F, CF, 3A would require extreme care defined by Motorola. Some of these in their use because of their somewhat extra instructions which are available odd results. C. Additional executable op -codes:

Op Code Addressing Boolean/Arith Cond. Code ReQ, Mode Operation HINZ V C

Logic Ops Op Code Addressing Boolean/Arith Cond, Code Req. Mode Operation HINZ V C 14 Implied A.B + A 2 2 R . 1A Implied A+B + A (OR) . 2 2 R 3A Implied (SP+2) -. 8 . . . . . (SP+3) A 1F Implied 8- A . 3 2 R S (SP+4) -.X (SP+S) + XI Arith Ops (SP+6) 4.PC 12,13 Implied A -B-1 + A .. 2 2 2 2 (SP+7) .e Pen 83 Immediate 1 (SP)+1 > SP 93 Direct A -M-1 A j 2 2 A3 Index

83 Extended I C3 Immediate D3 Direct Op Code Addressing Boolean/Arith Cond. Code Reg 6-M-1 8 . 3 2 3 2 Mode N Z Operation N I E3 Index F3 Extended Test ops 10 Implied A+B + A' 2 2 2 2 ¡ ,. 15 Implied A.B . . 2 2 R I . 1C Implied A+B11 + A . 2 2 2 . e 41 Implied 00-A 2 I OIO .48 Implied A-1 -.A 3 2 0 e 51 Implied 00-8 2 3 CO 58 Implied 13-1 -. 8 . 2 2 e I I . . R 0 45 Implied A10I I! rl il 2 C 2 b0 C SB Index b7 : )N_1 2 2 e 55 Implied BI . R 2 $ +M O 78 Extended

Iliac Ope

67 I..plied A +(PC)+2 2 3 R NOTE: Condition code symbols (PC)+3 +PC $ Test and set if true, cleared otherwise C7 Implied B . (PC )+2 I 2 R Not affected (PC)+3 -PC R Reset always S Set always 8F Implied SP (PC)+2 . I 3 R , SP,HH ...(PC)+3 1 Set if result = 10000000 (PC )+4 PC 2 Set if result= = 00000000 a + 3 Set equal to result of N C after shift has occured CF Implied X +(PC)+2 . 2 I R 4 Set if operand = 10000000 before execution XH (PC)+3 5 Set operand = 00000000 before execution if (PC)+4 Condition code result differs from similar existing operation +pc

56 ELECTRONICS TODAY INTERNATIONAL - MARCH 1978 MICROPROCESSOR CRYSTALS COMPU/TIME offers 7400 TTL Series FREQUENCY FREQUENCY A COMPU/TIME 7.0.0 IB 7441 75 7496 80 5.0 MHz $4.95 Real Darn Clever 7401 20 7442 so 4 74751 1.0 MHz $5.95 20 7443 I 20 74100 1 25 74162 1.8432 MHz 9.80 5.0688 MHz 4.95 CT 100 Enhancement to users of 7403 20 7145 1 05 74107 40 74163 7404 70 7440 1 05 74109 45 2.0 MHz 5.95 IMSAI/ALTAIR 7405 25 7447 85 5.185 Mhz 4.95 7:88 4766 2.097152 MHz 8.50 7406 .3Z 7448 Lill 4.95 Microprocessors 7407 74120 1.25 74167 5.7143 MHz 7450 20 55 7408 75 7451 74121 74170 6.00 MHz 4.95 74172 45 74172 2.4576 MHz 8.50 BUS 7409 25 7453 MHz 4.95 $100 COMPATIBLE 7410 20 7454 74173 95 74173 2.667 MHz 9.50 6.144 7411 75 74175 55 74174 MHz 4.95 74175 6.40 TIME & CALENDAR 7312 40 740 40 74126 .60 3.00 MHz 8.50 4.95 7413 75 7472 l5 74178 65 74176 6.5536 MHz 7416 35 7473 14132 1.50 74177 3.20 MHz 8.50 74136 1,80 74180 COMPU/TIME CT100 $199 Kit $245 Assembled 7417 74,4 40 3.2768 MHz 8.50 1420 20 7475 74141 1 15 74181 8.0 MHz 4.95 only C101 Assembled 74182 COMPU $149 XII $189 7422 75 7478 4100 74147 400 3.579545 MHz 1.25 MHz 74144 4 00 74184 10.0 4.95 TIME only T102 Kit Assembled 7425 35 7479 2 4.0 MHz 4.95 $165 $205 7480 74145 I 10 /4185 18.00 MHz 4.95 COMPU/TIME PC Board only _$ 60 7427 35 7487 I.50 250 74106 1 4.0 MHz 4.95 18.432 MHz 4.95 40 7483 85 74148 75 74190 1 4.194304 MHz 4.95 7429 ao 7415 1.10 00 20.0 MHz 4.95 .25 7488 40 7414151 10 74197 4.91520 Mhz 4.95 MM16 "EPROM 7430 .30 7489 2 25 74153 10 74193 22.1184 Mhz 4.95 7433 40 74 55 74154 10 74194 Ut 7zing up to 16 2708 EPROMS 74155 10 74195 27.0 MHz 4.95 7437 3D 7491 1 10 7438 35 1492 74156 10 74196 36.0 MHz 4.95 S 100 Bus Computer Systems 74157 20 74197 36 7493 9ó FOR PROCESSOR TECH 48.0 MHz 4.95 Me'nor, capacity Of 811 Or 16K bytes by DIP 7440 70 7494 74158 7495 9ó 36á 74;99 14.318 Oh bOundars addressing by DIP SwrICh $/'\ /' Boo $4.95 O to 4 waet c,Cles by DIP Switch 9JJ MJ 74151974 77i Data output address input roes lu1'y buffered 7445Ó » 74LS00 DIP SWITCHES 741502 7445795 ; é 7 POSITION 1.80 HI grade glass epo.y 151511 yualed-thru holes 745503 ñ 7451196 I 87 741504 7455138 115 74Lsr91 197 4 POSITION 8 POSITION 2.00 EDefy solder masked 145505 1.560 79 14L5221 200 $1.50 741508 29 141573 9 15139 25 741514 49 7415151 115 7115240 300 5 POSITION 1.60 9 POSITION 2.25 145153 35 )LSN1 300 745511 145575 69 14L5217 300 741576 9 741(5154 365 6 POSITION 1.70 10 POSITION 2.50 Net .e" Display 141.512 50 111.524: 160 FCS 80004 - 3v, - 71513 69 145578 65 1415155 125 1 75 1415156 85 1524 MEW' 29 Po V.r7en eh cola, a 40250 ,nd08l 7.5511 1 70 74L583.N t;11 1 745524] .1r61511 4U 741585 7 75 7455157 50 CnMctl simos0 one .1515 SS WIRE WRAP TOOL 141.570 29 /41.586 69 7.5158 74E1311 lo, one eel 3417. 34174 SLIT-NWRAP 89 7.5160 7.571 741.590 7415253 i aposmg 89 7415161 195 or D. ....lass .1 . Slits and opens inwlaeon 145522 741592 I 74L5251 I 15 .:122B' 17417 1.5593 /15516] 95 bar 94 re. 14/526 31 95 14Ls258 1 95 WIRE WRAP CENTER 55000410 1.5521 141595 1 50 7415163 7415259 4 25 . No pre-cutting o7 pre...100,n9g 1 1415164 S 10087 VIEW 4511000 It roman cvtm 140.578 141596 89 14157606 50 - 4,11n with two /00tt 7415107 .s5 /455165 2090 484 uapl woo. 10 Nis . Comes complete 741.530 79 SPECIAL No. AWG wire 39 1435109 59 7415166 2 OD 10 me, a e a spools. 28 741532 7i51r3 250 TOOL-BW-630 II 5 s .0 741537 7415117 7415168 74Ls2r9 19 HOBBY -WRAP 14.95 EA. earn 15 mA 7415113 Só 7415169 7 óó .. 741535 440 1115283 I BS C) *58100304 FORWARD Sonata 000434 drop 741540 39 1415114 60 1415170 400 7415189 616 Battery Operated (Sue 60 200 50 I 70 1.5122 416790 1 56 C0)4014/97- 25tr0 1 S .6s NpaM Mao 524 115174 9> Weighs ONLY 11 Ounces 744s47 25 7415123 173 74/5293 I 56 7415124 7 éo 74151/5 741544 1 68 7415795 200 Wraps 30 AWG Wire onto 141551 7445125 87 7415181 ] 69 7415298 200 . 711.552 7415128 107 7415189 741.5352 165 $34.95 Standard DIP Sockets (.025 inch) Plugboards 8800V 71L554 29 7115137 74L5361 9/ 7445191 7 0411.41,101~.41. /4L555 29 7415136 9 Complete with Du,n-m SI) and sleeve Universal Microcomputer 741.ú70 395 Processor plugboard, use with S-100 bus complete with CMOS heat sink & hardware 5.3 x 4050 61 4517 850 10x 1/16' 1.001 40 WIRE -WRAP KIT WK -2-W 4051 110 1516 1 65 - 4000 75 4519 4057 1 10 90 e '41 001 25 110 570 165 WRAP STRIP UNWRAP 4002 25 4053 4521 375 $19.95 350 4060 3 75 Tool for 30 AWG Wire 4061 100 4572 1 75 4006 1 40 41163 4571 30 AWG Wire 4007 250 300 Roil of 50 Ft White or Blue 26 4066 es 528 75 4006 25 00 4563 145 50 each I 2 3 6 4 lengths -- , 4. 4cw4041e 714402 N/lwllie17 f7snw 4009 4067 6 pcs 4584 15 4010 46 1368 35 4069 35 pre -stripped wire Freeze Action Speed Option 012 25 / N7V 44 CHANNEL F 4070 e6 Automatic time and scorekeepm9 4012 25 © so 4071 35 Vr0901 all 4072 35 $11.95 Battery -free AC operation 401 75 O >4[Arlt21 4015 4013 35 Dual controls with 8 -way action 75 35 v7409w1. M 4016 449 4015 4076 I65 No/ 5 Bun -in Pro Hockey and Terns games 4011 25 $129.9 >4010909Ñ 34o WIRE WRAP TOOL 4011 47 WSU-30 Easy hook-up on any B/W or Color TV ee 25 ]5] 4079 0 4078 35 074.91w 1045 4081 35 WRAP STRIP UNWRAP $5.95 Factory warranty 4021 1 25 054031444 2I5 40112 35 4071 1 ]6 4015 35 /4517.6155 ea. 0813 g3ü,aCs 11 w 2 Mayenl 44027 Channel F - additional cartridges - $17.95 4086 A5 ,e or 2 24 35 0814 Son 11 04)11,1 4069 OD 1409195 4,. WIRE 30 AWG 4024 00 WIRE WRAP 7oe/55o0rrgG1'ery 0815 -04+0112P far 1 sot 11 or 2018'51 041 2re41 - 0811 Sat 0819 ba0 4093 75 5007. 70 -1* 25 35 ;4CW 7;~ 7:5 1000/1 ma I» Mate 4098 5o 1,47.745 4/ 1200 509 $195 $1500 ouadraaomil7oaote 0020 12 01Krs1 4025 2 ]5 4517.9755 1160 75 0812-Dese? Po. /Sh3315gey , ,-]q - Red - I FL) sa'312payers) 4027 60 035, SPECIFY COLOR White - Yehow Green Blue Blau al" 4161 75 ;: 2 w 4/01.9265 17 00 - 4029 1 5 200 1767 75 4029 1 50 5,114C115/4 M 4rcJ 75 454 t4C92/5 1700 40300 60 140095 475 74 75 4033 I 60 :MM7409a4 32 .5174C92eN 1200 WIRE DISPENSER WD -30 D -SUB CONNECTORS 1 5 60 .' 14.935 111 - 4034 200 4191 9/4740945 161 4035 350 B5 50 /1 roil 30 AWG KYNAR wire wrap wire NO. PINS PART NO PRICE COVER PRICE 30 53,45 ea. 4035 501 9wYgrN 1501 15 M54740r505 561 Cuts wire to desired length 4030 so 005414Cr116 590 i5 1 25 450] IS 50.0119 BlueYellowWhneIAed 9 DE 9P 1 49 SU Stnps 1" of insulation - 4506 ro 4ów1 45 15 00 9 DE 95 2 4042 25 450/ 500 01 15 DA 15P 2 11 1 5(1 20 4044 25 450 1S 15 155 10 1511 U0 LIQUID CRYSTAL DIGITAL DA 3 4045 50 111 50 25 D8 25P 3 00 1 50 4046 CLOCK -CALENDAR w 75 25 DB 25S 400 1515 75 0488 m ./4/¢I66N 161 Auto, Home. Office 37 DE VP 4 14 200 4049 r íZ::151fi 15 For 37 DE 37S 6 00 Small in size (2x2V2x47) for 50 DD SOP 5 40 2 25 Push button for seconds release date with e0her 3M double 50 DD SOS 8 00 Clocks mount anywhere 1.03074. 1 10 sled tape or VELCRO. included. 1.1.130181451301A0 INEARL4111'N 1 lo 2 MODELS AVAILABLE 11 1.2m115 runs on Sell Contained EDGE CONNECTORS 1.1021. /5 12:28 LCD.? 01, portable model 10runN ) I5 150 L for better than a year. 5Mp6N 1M7-.. ' 3011 batteries .0 pi.S 111 503070 55 is 1 A7m.,N 160 runs on 12 Volt System and back 15 LpCD 102, 187076 1.701/119 149 IE9 10 G S 50 183ne40 1 75 LM 513/1545 20 0-41. 41h l' 11425116 700 ea 1.5130eA6 100 LCD 111001 w LCD 102. your chase $ 33.95 IS PIN G On 75 15110350 405 411134144 5 25 30 OVAL I M3080 100 44 Dual 22 PIN GOL. 1 95 1020904l67y 5 SO 103106 lr0 1.617104014 50 44 22 COIL 2.50 115 1495404 75 Clear desk stand tor ...... $2.00 DUAL PIA 1/43106 LOA /ION 75 114 0658 4.95 700 00 80 DUAL 40 pIN SOLD 1.31044 10211C14 149k IN 260 43 GOL S 00 183710 200 86 DUAL PIN DI138001 90 1M111CN 39 10030299 I IS ÁL14141 A-25 1.31114 2304 00 100 DUAL 50 PIN GOLOIIMSAI 1003119 en VA y5 3 AL 101) 4.95 10725C0 55 4.714fiN 700 MODULE 100 DUAL SO PIA GOL Dl105Á1. 1.3114 eO 1433575 MA1003, 12V DC CLOCK PIA CARS-IMSAI 3.50 1M3130 /0 167725C14 250 2 100 DUAL 50 6010150 1Mtt725CN 1434015 4/431904 1 SO ?l IDO DUAL 50 PIN 71. ( I SPACING) 3.25 >w ;M79a9 on Oiled /43196 IS1 l 9n - -y 'Built X'TAL cont. 1.0/3.3C51 '00 against 103195 1 25 911 bese. Pro beer ALTAIR/IMSAI CARO GUIDES 254 CAC» 1/8739619 91$ ! : time 1032114 300 14. 1114 automotiv e volt 1 411..4.. ts. 1.3225 300 LM741C14 35 con. 166 1.117410114 35 } Automatic brightness 1032114 1104074N 2 15 300 147410'1 39 r) 1701 with 0.3- green color CLOCK CHIPS 1003355 16771106 39 1.51404414 300 turno11 L M339N 99 10742C14 L84250CN 104 display. Display 44145309 6 Dept; 8C0 Outputs Rebel PIS 59 95 (M3.970 I85 LM 7C51 M L44250CN 00 with ignition TOFF" MM531 1 6 Pyt, BCD Outputs 12 or Roar 495 1003506 100 24 10146(14 A 1.455614 5 1.35014 1 00 17.95 MM5311 4 091 BCO Outputs 1 PPS Output 4 95 1.1.4741815 39 1.437014 115 51451567 1 15 14545314 6 3101, 12 Or 24 Hour. 50 CA 6011 495 75 1.511(9[6 310 103106 7 1155585 I 00 44M5316 4 Drat. Alarm. 1 PPS Output 6 95 103150. 795 1.1413035 90 9 103155 300 MA15318 Video Clock Chip. For Use With (14M5814 59 95) 95 L1.1.30415; 19 103775 700 RCA SERIES CT7001 6 D,grt. Calendar Alarm. 12 o 24 Moor 5 95 3056 40 Lietee UNISON 1 w M39..5 108 14130770 85 L 1M131051 003513 2 15 L 51x..6 I 05 275 L51135870 100 CA3023 )56 Computer Products 1 75 1.14206 CÁ3035 2 48 1M1414N 1 l5 1.1135218 1 /5 CÁ3039 135 11/1115814 1 30 I C SOCKETS LMg60 85 CA3046 30 5351 WEST 144th STREET Wire Wrap LMxIAN t5 1014505 59 151146814 790 CA3o59 3 25 1.1438114 95 553160 325 LAWNDALE, CALIFORNIA 90260 Lo Pro11141 BOldr Tin 1 PV 124 25 99 100 999 111 (030014 12S /014586 95 1.01.896 I C43ow1 PIN 1 24 75 99 100 999 16 s 381 10 39 36 32 26 7 25 95 LMN196 95 12131 679-3313 8) 15 14 13 12 29 141149611 16 34 33 31 10149651 95 CÁ3®1 200 14) 25 10 16 11 16 36 34 32 30 14E53111V 700 CA3082 150 565500 L0155044 I /5 Discounts available at OEM quantities. All prices above are quoted in US 25 20 18 16 10 70 60 54 40 30 CÁ3053 1 60 6E5553 l9 1.1596/ 25 18 . 27 26 20 75 CÁ3006 $F.0.13. Lawndale, Calif. USA. To expediate shipments please Include Interna- 18) 20 ee 67 55 61549 125 10010005 190 34 33 30 239 22 95 80 71 59 6(5408 500 1.180014 Gm C4xe9 3 75 tional money order or bankers check Payable against any USA bank In US$, or 0.3130 1 19 122) 36 35 34 28 24 95 so 71 59 SO1 310191070 :00 5F5520 01 Bank America or Master Charge welcome (Include (24) 34 289 71 1671811N 00 063140 I 2 affiliated credit cards 36 35 28 95 e4 80 OF /6591 S0 C4140. 44 43 42 367 125 108 83 5E5669 700 1018206 125 card No., expiration date and signature). Add 10 percent of total order for (281 140 1/410936 41501 3N se 57 493 89 965661 V I 75 700 (401 60 436d 1S6 140 120 postage. For less than add $1.50 service charge. NE561V 159 10184574 75 orders $10 Project 639 1_ _in 'oor e Every home should have one - so make it a good one, say T. Long and T. Wooller of Applied Technology.

THE ADVENT of the microprocessor is more than just a remarkable technological achievement, it is destined to impact all our lives in the very near future. Instead of large, incredibly expensive computer installations these remarkable devices offer complex computing power at a low cost that is still diminishing. This article shows how a microprocessor can be used as the basis of a relatively simple device such as a musical # f i t doorbell. The finished product is elegantly simple, yet costs little more than the current top -of -the -range electro- mechanical doorbell on the market today. From a functional point of view, the doorbell consists of a PCB containing a SC/MP microprocessor, preprogrammed 512 byte ROM, a TTL quad gate package, a handful of resistors, capacitors and transistors and a speaker and battery pack which attach to the back of the board. The doorbell is programmed to play eight tunes which are selected with various push -buttons and one wire link on the PCB. The tunes are: Waltzing Matilda Greensleeves Can Can 'Rule Britannia Trumpet Voluntary Twinkle Twinkle Little Star Colonel Bogey March Computer Music

Basic Design Approach The ETI Microprocessor Doorbell has been designed to demonstrate how effectively a microprocessor can carry out even the most simple tasks. In this

58 ELECTRONICS TODAY INTERNATIONAL - MARCH 1978 ,

_j, at. - > t> 41 HOW IT WORKS - ETI 639 1 Ir -t t.= --i /10 4 4,44k.49 When a pushbutton is pressed the 74LS00 L(i- l tests which sense inputs of the SC/MP Ii" J gate ` v , chip are activated. Simultaneously the operation of the pushbutton initialises ` the SC/MP chip and program execution Fig. 1. Speaker Mounting on rear of PCB. starts' from location 0001. This action also applies temporary power to the SC/MP PRl PBI PUJ P94 and the ROM. The first step carried out by the SC/MP i:i°áiQl 11 11 I is to set the output at the SERIAL OUT I (SOUT) pin to high, which in turn ensures that power remains on when the VE pushbutton is released. UNREGULATED Next the SC/MP tests the SENSE A and SENSE B inputs and decides which tune has been selected. At this point the tune is played. On completion of the tune the SC/MP sets the SERIAL OUT pin low and turns the battery supply off. If the pushbutton is still pressed the tune will start again. Refer to the complete circuit diagram for an indication of how the actual operation is achieved. For those software oriented types the program listing on page 60 could be analysed as a flow chart with assembly listings or suitable description for the machine code. VE UNREGULATrQ

Fig. 2. Circuit diagram of doorbell.

PARTS LIST - ETI 639

Resistors all 1hW, 5% unless stated R1 1k R2 4k7 R3 560 R R4 -R6 4k7 R7 100R R8 1k R9 6k8 R10 -R12. 4k7 RV1 2k2 Capacitors Cl 114, electrolytic C2 68n C3,4 68p Semiconductors IC1 ISP8A/600 (SC/MP II) IC2 82S115 PROM (pre- 1..14 programmed) Ic3 IC3 74LS00 01-D4 1N4148 Q1 BD136 Q2,3 BC548 04 8D139 ISPKR Miscellaneous VE PCB ETI 639 _VE 01-04 TUNE PUSH BUTTON LS1 8 ohm speaker BANK TERMINALS 10 solder pins, 6V battery, battery SELECT connector, picture frame for mounting.

Fig. 3. Component overlay.

ELECTRONICS TODAY INTERNATIONAL - MARCH 1978 59 Project 639

08, C4, 01, 01, 06, 19, 1C, 1C, 1C, 1C, 01, 1C, 1C, IC, 1C, 1C, 3C, 2C, 35, 63, 50, 32, 00, 07, 50, 43, FF, 2C, 77, 35, 64, 00, 08, 58, D4, 07, 01, C4, 58, 32, 40, OD, 01, E4, 98, C6, FF, 9C, 81, 35, 64, 32, 69, 2C, 77, 19, C6, 00, 28, 19, C6, 00, 28, 20,

FA, 40, F4, FF, 02, 01, 90, FO, C2, 01, 35, C2, 00, 98, 12, E4, 00, FF, 3C, 59, 3C, 43, 3C, 17, 3C, 59, 48, 4B, 2C, 77, 2C, 59, FF, 98, DO, C4, 07, 07, C4, 00, 8F, 00, C2, 00, F4, FF, 02, 9C, 2C, 1E, 2F, 6F, 35, 64, 3C, 59, 3C, 43, 3C, 17, 35, 64, 3C, 43,

F8, 07, C2, 00, F4, FF, 02, FB, 9C, 35, F4, FF, 02, 98, 03, 35, 3C, 17, 3C, 59, 44, 38, 48, 13, 50, 66, FF, 27, C6, 27, 43, 24, 90, D9, C6, 02, 8F, 10, 90, DO, 44, 4F, 44, 4F, 2C, 77, 2C, 77, 48, 24, 8F, 27, 43, 24, 48, 27, 43, 2C, 3C, 32, 35, 35, C7, 20,

27, 85, 27, 85, 2C, EC, 32, 69, 32, 69, 35, 64, 35, 64, 3C, 59, 9F, 24, 8F, 27, 22, 32, 18, 24, 24, 2C, 1E, 20, 60, 24, 48, 27, 3C, 59, 44, 9D, FF, 35, 64, 2C, EC, 27, 85, 22, El, 20, 50, 22, 85, 2C, 77, 32, 3C, 32, 61, FF, 2C, 3C, 2C, 38, 27, 22, 20, 28,

96, 27, 00, 2F, 70, 3C, 85, FF, 3C, AF, 35, 94, 3C, 16, 35, 19, 22, 26, 27, 22, 1C, 5A, 1C, 5A, 1C, 2D, 19, 32, 22, 26, 20, 28, 2F, A6, 2C, 38, 2F, 6F, 35, 63, 3C, 58, 35, 63, 2F, 6F, 35, 31, 27, 43, 27, 43, 27, 22, 20, 28, 22, 26, 27, 22, 2C, 54, FF, FE,

80, 01, 08, 02, 08, 03, 08, 04, 08, 05, 08, 06, 08, 07, 08, 08, Fig. 4. This object code listing of the doorbell program will enable 08, 09, 08, OA, 08, OB, OS, OC, 08, OD, 08, OE, 08, OF, 08, 10, owners of SC/MP based microcomputers to generate tunes. This program is not the same as the one in the PROM as the address lines to the PROM are swapped about 08, 11, 08, 12, 08, 13, 08, 14, 08, 15, 08, 16, 08, 17, 08, 18, 08, 19, 08, 1A, 08, 18, 08, 1C, 08, 10, 08, 1E, 08, 1F, 08, 20, case the microcomputer is designed. to select and play any one of eight tunes; it 08, 21, 08, 22, 08, 23, 08, 24, 08, 25, 08, 26, 08, 27, 08, 28, controls the actual program sequence, 08, 29, 08, 2A, 08, 2B, 08, 2C, 08, 2D, 08, 2E, 08, 2F, 08, 30, turns the battery supply off after every tune and mathematically determines the 08, 31, 08, 32, 08, 33, 08, 34, 08, 35, 08, 36, 08, 37, 08, 38, pitch and duration of each note. The 08, 39, 08, 3A, 08, 3B, 08, 3C, 08, 3D, 08, 3E, 08, 3F, 08, 40, output is monophonic and consists of 08, 41, 08, 42, 08, 43, 08, 44, 08, 45, 08, a square wave driven into a speaker. The 46, 08, 47, 08, 48, 08, 49, 08, 4A, 08, 48, 4C, actual program and the tunes played are 08, 08, 4D, 08, 4E, 08, 4F, 08, 50 contained in a separate ROM, and other 08, 51, 08, 52, 08, 53, 08, 54, 08, tunes could readily be programmed by 08, 55, 56, 08, 57, 08, 58, 08, 59, 08, 5A, 08, 58, 08, 5C, 08, 5E, 08, 5E, 08, 5F, 08, FF, selecting a different ROM.

Assembly Assembly of the doorbell is very straight- forward. To minimise costs no sockets are provided and the microprocessor and ROM solder directly into the PCB. Refer to the PCB overlay drawing and study the location of every component before starting assembly. Start with the resistors and capacitors. N ext i n sertth a dí odes, watch in g carefu I I y that the cathode ends of the diodes are correctly oriented. Now mount the microprocessor, ROM and TTL gate as well as each of the transistors. Take the usual precautions not to overheat individual joints. Note that the microprocessor is fully protected internally and is not nearly as prone to damage as CMOS (but it should be handled carefully just in case!). Next solder PC pins as indicated for the loudspeaker, battery and pushbutton connections. Now glue the loudspeaker to the rear of the PCB, using epoxy or similar glue. Solder the leads to the correct pins on the PCB. Recheck the wiring thoroughly and connect the power to the board '(taking care to avoid reverse polarity). Now short one of the pushbutton terminals and a tune should be played. Adjust RV1 to give the desired pitch and your doorbell is ready for use.

60 ELECTRONICS TODAY INTERNATIONAL - MARCH 1978 LEDS, etc. SOCKETS/BR I DG ES TRANSISTORS, DIODES/ZENERS .15 pcb .25 ww .45 2N2222A NPN (2N2222 Plastic .10) 1N914 100v 10mA .05 8 -pin 2N2907A PNP .15 .25 ww .40 1N4005 600v 1A .08 14 -pin pcb 2N3906 PNP (Plastic) .10 1A .15 16 -pin pcb .25 ww .40 2N3904 NPN (Plastic) .10 1N4007 1000v .35 .05 18 -pin pcb .25 ww .75 2N3054 NPN 1N4148 75v 10mA 2N3055 NPN 15A 60v .50 22 -pin pcb .45 ww 1.25 1 N 753A 6.2v z .25 T1P125 PNP Darlington .35 ww 1.10 1N758A 10v z .25 24 -pin pcb .35 LED Green, Red, Clear, Yellow .15 ww 1.45 7 seg High corn -anode 1.95 1N759A 12v z .25 28 -pin pcb .35 D.L.747 5/8" XAN72 7 seg corn -anode (Red) 1.25 z .25 40 -pin pcb .50 ww 1.25 1N4733 5.1v MAN71 7 seg corn-anode (Red) 1.25 1N5243 13v z .25 Molex pins .01 To -3 Sockets .45 MAN3610 7 seg corn -anode (Orange) 1.25 z .25 MAN82A 7 seg corn-anode (Yellow) 1.25 1N5244B 14v 2 Amp Bridge 100 -pry 1.20 .25 MAN74A 7 seg corn-cathode (Red) 1.50 1N52458 15v z 1.25 25 Amp Bridge 200 -pry 1.95 FND359 7 seg corn-cathode (Red) - T T L - C MOS .40 .15. 7473 .25 74176 1.25 74H72 .45 74S133 4000 .15 7400 -.55 7474 .30 74180 .75 74H101 .75 74S140 4001 .15 7401 .15 74S151 .30 .20 7475 .35 74181 2.25 74H103 .75 4002 .20 7402 74S153 .35 7403 .20 7476 .40 74182 .95 74H106 .95 4004 3.95 74S157 .75 4006 .95 7404 .15 7480 .55 74190 1.75 .25 74S158 .30 4007 .35 7405 .25 7481 .75 74191 1.05 7400 74L02 .25 74S194 1.05 4008 .95 7406 .35 7483 .95 74192 .75 74 L03 .30 74S257 (8123) 1.05 4009 .45 7407 .55 7485 .75 74193 .85 74 L04 .30 4010 .45 7408 .25 7486 .25 74194 1.25 74L10 .30 74 LS00 .25 4011 .20 7409 .15 7489 1.35 74195 .95 74 L20 .35 74 LS01 .35 4012 .20 7410 .10 7490 .55 74196 1.25 .45 74LS02 .35 4013 .40 7411 .25 7491 .95 74197 1.25 74L30 1.95 74 LSO4 .30 4014 .95 7412 .30 7492 .95 74198 2.35 74L47 74L51 .45 74 LS05 .45 4015 .90 7413 .35 7493 .35 74221 1.00 .65 74LS08 .25 4016 .35 7414 1.10 7494 .75 74367 .85 74L55 74L72 .45 74LS09 .35 4017 1.10 7416 .25 7495 .60 .40 74LS10 .35 4018 1.10 7417 .40 7496 .80 75108A .35 74L73 .45 74LS11 .35 4019 .50 7420 .15 74100 1.15 75110 .35 74L74 .55 74LS20 .25 4020 .85 7426 .30 74107 .35 75491 .50 74L75 74 L93 .55 74 LS21 .25 4021 1.00 7427 .45 74121 .35 75492 .50 .85 74LS22 .25 4022 .85 7430 .15 74122 .55 74L123 74LS32 .40 4023 .25 7432 .30 74123 .55 74H00 .15 .25 74S00 .35 74 LS37 .35 4024 .75 7437 .30 74125 .45 74H01 .20 74502 .35 74 LS40 .45 4025 .30 7438 .35 74126 .35 74H04 .30 74LS42 1.10 4026 1.95 7440 .25 74132 1.35 74H05 .20 74S03 .35 74SO4 .30 74 LS51 .50 4027 .50 7441 1.15 74141 .90 74H08 .35 74 LS74 .65 4028 .95 7442 .45 74150 .85 74H10 .35 74S05 .35 74 LS86 .65 4030 .35 7443 .65 74151 .65 74H11 .35 74S08 .45 74S10 .35 74 LS90 .95 4033 1.50 7444 .45 74153 .75 74H15 .30 74S11 .35 74 LS93 .95 4034 2.45 7445 .65 74154 .95 74H20 .25 74S20 .35 74 LS 107 .85 4035 1.25 7446 .95 74156 .95 74H21 .40 74S40 .20 74 LS 123 1.00 4040 1.35 7447 .95 74157 .65 74H22 .20 74S50 .20 74 LS 151 .95 4041 .69 7448 .65 74161 .85 74H30 74S51 .25 74 LS 153 1.20 4042 .95 7450 .25 74163 .85 74H40 .25 .25 74S64 .20 74LS157 .85 4043 .95 7451 .25 74164 .60 74H50 .25 74S74 .35 74 LS 164 1.90 4044 .95 7453 .20 74165 1.50 74H51 .15 74S112 .60 74LS367 .75 4046 1.75 7454 .25 74166 1.35 74H52 .25 74S114 .65 74LS368 .75 4049 .45 7460 .40 74175 .80 74H53J 74H55 .20 74C04 .25 4050 .45 7470 .45 74C151 2.25 4066 .95 7472 .40 4069 .40 REGUL ATORS, etc. 4071 .35 MCT2 .95 LINEARS, 1.65 LM340K15 1.25 LM723 .50 4081 .70 8038 3.95 LM 320T5 1.65 LM340K18 1.25 LM725N 2.50 4082 .45 LM201 .75 LM 320T 12 .95 LM739 - 1.50 LM301 .45 LM 320T 15 1.65 LM340K24 MC 14409 14.50 LM741 (8-14).25 LM308 (Mini) .95 LM324N .95 78L05 .75 MC 14419 4.85 LM747 1.10 LM309H .65 LM339 .95 78L12 .75 LM1307 1.25 LM309K (340K-5185 7805 (340T5) .95 78L15 .75 LM1458 .95 9000 SERIES LM310 1.15 LM 340712 1.00 78M05 .75 LM 3900 .50 9301 .85 95H031.10 LM311Dwino .75 LM 340T 15 1.00 LM373 2.95 9601 .45 LM75451 .65 9309 .35 LM318 (Mint) .95 LM 340T 18 1.00 LM380 (8-14 PIN) .95 9322 .75 9602 .45 (8,14 PIN).25 NE555 .50 LM 320K 5( 7905)1.65 LM340T24 .95 LM709 .45 NE556 .95 LM320K12 1.65 LM 340K 12 1.65 LM711 MICRO'S, RAMS, NE565 .95 CPU'S, ETC. NE566 1.75 74S188 3.00 NE567 1.35 1702A 4.50 INTEGRATED CIRCUITS UNLIMITED MM5314 3.00 3.50 MM5316 Diego, CA 92111 U.S.A. 2102-1 1.45 7889 Clairemont Mesa Blvd., San SPECIAL 2102L-1 1.75 No Minimum 4.50 DISCOUNTS TR1602B postage to cover method of Total Order Deduct L 14.50 All prices in U.S. dollars. Please add TMS 4044-45N $35 - $99 5% 8080AD 12.00 Orders over $100 (U.S.) will be shipped air no charge. shipping. $100 - $300 10% 8T13 1.50 with order in U.S. dollars. Payment should be submitted $301 - $1000 15% 8T23 1.50 received. All orders shipped same day - Up 20% 8T24 2.00 All IC's Príme/Guaranteed. $1000 8T97 1.00 A 4.00 American Express / BankAmericard / Visa / MasterCharge 2107B-4, Phone (714) 278-4394 Barclay Card / Access / 2708 11.50 NEW MODEL, 3-30 MHz BI -LINEAR HF-3-100L2 AMPLIFIER Frequency Range 3-30 MHz Input Power: IOW Nom, 5-20 W PEP range Output Power: ± 100W Nom y2 dB across band 200-250W PEP output Input Impedance: 50 ; nom, adjustable to match exciter range under 2 1 across band er Mx rwM oM MOM NM oM Output Impedance: 50 9, nom, up to 3:1 VSWR acceptable with little degradation 0 Current Drain: 16A nom. A 0 o 20 supply recommended at 13.6 VDC art ON Of O. sa Power Supply: 13.6 VDC recommended for best results, 11.14 VDC acceptable i { positive or negative ground Pre -amp: 18 dB nom. gain »..0 t,. 1,.., R..,. across entire HF band, 15 dB typ at 50 MHz, 3-4 dB NF Size: 19 1 x 16.5 x 8.9 cm wt 1Y2 Kg DEALERS ENQUIRIES WELCOME SOLE AUSTRALIAN DISTRIBUTORS FOR SCS LINE OF LINEAR AMPLIFIERS

PHONE 2124815 EIT1O11f P.O. BOX K21, electronics HAYMARKET, N.S.W. 2000

memory_ GYOURROW own ON STACKABLE 4K RAM/ROM PLANES RAM PLANES ROM PLANES 4K Bytes using 32 2102s 4K bytes using 4 2708s PCB KIT 450 nS PCB KIT (no 2708s) $15.75, $89.30 $15.75, $34.90

EXPANDABLE 16K MOTHER BOARD All buffering and control Interfaces to 6800, 8080/ 7 for 1 to 4 RAM/ROM planes 85, 2650, SC/MP etc. R.sf44.tt MEMORY PLANES stack Edge connector.43 x 2 .: on sockets way 0.156" with Motorola Configurable to any 8K system connections. boundary . KIT - $49.20 /Prices inc. tax and P&P In Australia)

Pennywise Peripherals 19 Suemar St., Mulgrave, Vic 3170. Phone (03) 546 0308

FRONT PANEL NUMBER CRUNCHER BACKPLANE BOARDS U. . EPROM ERASER MM57109 Number Cruncher. Buffered 1/0 gold plated edge WIII erase up to 4 Eproms at a connector will suit 8080, 6800. time In 30 mins. 240V operation SCAMP, etc., will perform float- - portable - assembled price -Y0 ,of+lrep' ing point and scientific calcul- ations under software control. $47.50 f 1.41%.09 Full data and software support. KIT PRICE BUILT AND $52.00 TESTED $72.00 SINGLE STEP CONTROL Designed for 8080 but for 8080 will suit PAPER TAPE READER Push button single step most systems. Input lines are 16 Quality mode. ADD. Lines, 8 Data lines, x fibreglass boards, 5 Auto. step low speed (Variable 2 8 sockets per board with side speed) mode, Interrupt facility. Bit grog. output port, status spacing, flats etc. All Inputs buffered, provision for linking Run mode LED, will suit other flat cable interface. Also avail- o__, boards together even different systems, works off wait, & types, ready, able as an option a HEX DIS- lines. Panel mount. PLAY with 'h" high 7 seg. Led 10" x 8" 6800 board with wide KIT BUILT AND display for Address & Data Bus. centres PRICE TESTED 4 r x displays for address ! 12" 6" 8080 board with pro- bus and 2 _ vision displays for data bus. 10 x 8 for both sockets $23.00 Inches. $33.00 PANEL $75.00 Manual operation, self Contain- PRICE $_24.50 KIT PR CED ed In case 160X110X50. Flat ALL PARTS POST FREE cable Interface GOLD PLATED WITH to 1/0 port. SOCKETS See adv. JAN 78 Elec. Aust. for HEX DISPLAY $105.00 Handshake logic, Status LEDS, To suit & digital KIT PRICE Data & 8080 6800 43 way tacho, stop watches, tran. software supplied. double sided $9.50 or 5/ $45.00 Ign. system, burglar alarm etc. BUILT AND BUILT AND Simple to use on all systems. TESTED 8080, 6800, etc. TESTED S. M. KIT BUILT A ELECTRONICS 10 Stafford Crt, Doncaster East, $95.00 $125.00 PRICE $75I TESTED ND $95 3109. Box 19, Doncaster East, 3109. (03) 842-3950 (03) 842-3950

62 ELECTRONICS TODAY INTERNATIONAL - MARCH 1978 c

n NESSEL AUDIO

NEW NESSEL

PROFESSIONAL SERIES 15 LOUDSPEAKER

* Designed and made in Australia * Eight different tunes Only * Accepts up to four doorbells * Re -programmable with different tunes s3910 J * Novel picture frame design

This year, for electronics buffs at least, the old fashioned mechanical doorbell is out style. With microprocessor prices hitting an all-time low, it is economically of MODEL SL1502 feasible to have a microprocessor doing nothing but playing tunes whenever visitors press the button! Well, ETI and Applied Technology,have gotten together and done it. Here's the Voice coil diameter 4" first microprocessor -based musical doorbell project to be published in any magazine Magnet structure weight 9 kilos world-wide! True, other musical doorbells are. available, but nothing quite like this Cone resonance 55 Hz one. For instance, you can write your own tunes and program a PROM to play Power handling 150 Watts them with other designs using mask -programmed ROM this is not possible. This speaker is suitable for - musical amplifying systems, If you share a flat, as many of our readers do, then everyone can have their own PA, sound reinforcement, tune! discos etc.. . Since not everyone has a PROM programmer, and to make it easy to get all the bits together so you can start building, we have arranged for Applied Technology to supply complete kits of parts for the doorbell. These will be available to ETI readers at the special price of $39.50 + $2.50 for packaging and certified post anywhere in Australia. Allow three weeks for delivery. TRADE ENQUIRIES WELCOME Available from ETI DOORBELL OFFER Please make cheques payable to 'Doorbell Offer', and send orders to Doorbell Offer, ETI Magazine, 15 Boundary Street, Rushcutters Bay, N.S.W. 2011. NESSEL AUDIO NAME 9 Nellbern Rd, Moorabbln East, Vic. 3189 ADDRESS Ph (03) 95 9510 POST CODE

I enclose cheque/postal order for . . for . Musical Doorbells.

ELECTRONICS TODAY INTERNATIONAL - MARCH 1978 63 design and produce your own PRINTED CIRCUIT BOARDS

MAGAZINE PROJECT BISHOPS GRAPHICS HOBBYPACKS PRINTED (with full instructions) BLACK TAPES: CIRCUIT BOARDS CCT201 20yd rolls $1.55 Specify width .031", .050", .062" FEBRUARY 1978 EA.78C2 Cassette Deck $3.65 .080", .100", .125", .150", .200" EA.78AF2 Active Filter $3.50 ET1.487A Spectrum Analyser $4.75 DONUT PADS: (all with .031" hole) $1.20 ETI.487B Spectrum Analyser $4.75 ETI. 483 Level Meter $2.60 CCD216 88 pads .08" O.D. JANUARY 1978 EA.77TH12 Thermometer $2.50 CCD101 88 pads .10" O.D. EA.77CB12 C.B. Selective Calling $2.50 CCD102 125 pads .125" 0.D. EA.78CF1 Cross Fader $2.50 CCD103 125 pads .150" O.D. EA.77UP6A Nicad Memory $3.50 ET1.637 Cassette Interface $2.50 CCD138 125 pads :187" O.D. ETI.806 Skeet Game $3.00 CCD139 125 pads .200" O.D. DECEMBER 1977 77PM12 Poker Machine $4.25 CCD141 125 pads .250" O.D. 77UP11 Microprocessor Tester $8.50 ETI.450A Audio Delay Line $2.50 DUAL IN LINE: $1.20 ET1.450B Audio Delay Line $2.50 CCD6014 16 only 14 pin NOVEMBER 1977 77MX11 Mixer $2.50 CCD6004 only 16 pin 77SC11 Electronic Scanner $3.25 77PS11 5v/10A Power Supply $2.50 ARTWORK FILM: (.10" dropout grid) 77TS9 Test Tone Generator $3.00 ETI.245 White Line Follower $2.00 CC1489 8'h x 11" sheet $ .54 ET1.486 Howl Stabilizer $ 3.00 CC1476 17" x 11" sheet $1.05 OCTOBER 1977 ET1.586 Shutter Timer $2.50 ETI.135 Digital Panel Meter $2.50 SEPTEMBER 1977 EADVM Mini DVM $2.50 EA+10 Trafficator Repeater $2.50 ET1713 Add on FM Tuner $3.25 RISTON COATED LAMINATE ET1604 Metronome $2.00 ETI585R Ultrasonic Receiver $2.00 SINGLE SIDED ETI585T Ultrasonic Transmitter $2.00 AUGUST 1977 EA77AL/8 Headlight Switch $2.50 10" x 12" $8.91 EA77QBF7 Test Generator $3.00 6" x 10" $4.46 ET1583 Gas Alarm $2.50 5" x 6" $2.23 ETI134 True RMS Voltmeter $2.50 ET1603 Sequencer $2.50 JULY 1977 EA77B7 Burglar Alarm $2.50 DOUBLE SIDED EA77D7 Dwell Meter $ 2.00 10" x 12" $11.28 EA77DLT7 Digital Logic Trainer $10.00 EA77TTY7 RTTY Regenerator $2.50 6" x 10" $5.65 ETI484 Compander $ 3.50 5" x 6" $2.82 íT1317 Rev. Counter $2.00 ET1582A Home Alarm $3.50 ET1582B Home Alarm $2.50 "RISTON" DEVELOPER: $1.09 JUNE 1977 EA77E05 MOS Keyer $ 3.00 500m1 EA77UP6 SC/MP Memory $2.50 ET1485 Equaliser $ 3.00 "SCOTCHCAL" EXPOSURE FILM 8007: ET1581 Dual Supply $2.00 íT1547 Bell Extender $2.50 10" x 12" sheet $ 2.50 ET1712 CB. Power Supply $2.50 10" x 12" pack of 10 sheets $20.00 ET1481M Mixer $2.50 8500 developer 100m1 $ .80 MAY 1977 EA77PRE5 CB. Preamp $2.00 EA77TT76 RTT7 Modulator $2.50 EA77UP5 Mlniscamp $5.00 ETI549A Metal Locator $2.50 ET1584 Strobe $2.50 ETI481 Power Supply $6.00 PROTQ BOARDS ETI444 5w Stereo Amp. $1.00 APRIL 1977 77TT4 Transistor Tester $2.00 (48 hour service) 77CC4 Cassette Interface $3.50 ET1133 Phase Meter $2.50 We have on hand stocks of precoated laminate. You ETt631-2 Keyboard Encoder $3.50 supply 1:1 artwork or negative and we will have a We stock a complete range of PCB from E.A. and E.T.I. from 1976 single or double sided prototype ready in 48 hours or and new project boards are available as soon as each magazine is published. less. Please write for details.

I banMcard POSTAL ADDRESS P.O. Box 355, Hornsby, 2077 APPLIED !Icome TECHNOLOGY SHOWROOM 109-111 Hunter St., Hornsby 2077 (9-5 Monday to Sat) 1 PTY. LTD. PHONE 476 4758 - 476 3759 ECONOMY POWER SUPPLY LOW COST V.D.U. Ideal for microprocessors, this kit supplies +5v/ As described in E.A. February, this compact 10A, +12v/1A, -12v/1A fully regulated (S100 users V.D.U. is an ideal peripheral for microprocessor can use the +8v. ±16v unregulated outputs as well) systems. and optional overvoltage protection can be fitted. - 32 characters/line. 16 lines. This comprises of transformer, bridge rectifier and all - parallel ASCII (TTL) input. diodes, filter capacitors, PCB. regulatoi's and full - video output. assembly instructions. Can be readily adapted to fit - 1K on board memory. any metal work. - Automatic scrolling, carriage return, line feed. - screen clear facility. $49.50 KIT EPS.100 - uses low power TTL and MOS devices. Package and Post $3.50 - requires +5v at 800 M.A. -12v at 30 M.A. - Plated through hole PCB. - supplied with full instructions and trouble shoot- CASSETTE INTERFACE ing guide and Xtal.

Adapted from a design described in Radio LOW COST V.D.U. Electronics, this 300 baud interface uses the Kansas $99.50 Pack and Postage $2.50 City standard 1200/2400 Hz. encoding. Easily constructed, using standard TTL chips and a special test tape is supplied to simplify alignment. Kit is supplied TRISTATE LOGIC PROBE with PCB, all components, test tape and full device works with TTL circuits instructions. This very simple and TTL compatible levels from microprocessors and $22.50 KIT R.E.C.I. identifies LOW LOGIC STATE Pack and Postage $1.00 HIGH LOGIC STATE. FLOATING OR H1 Z INPUT. EXCESSIVE OR INSUFFICIENT VCC. S100 PROTOTYPE BOARD Also doubles as a pulse injector! Kit consists of PCB, IC's, LEDS, RESISTORS/ This is an ideal card for any prototype work. CAPACITORS and full instructions. Consists of top quality tin plated PCB with hard gold S100 edge fingers. Will suit virtually any IC package, $2.50 POST FREE plane and provision for on card has power and ground OR voltage regulator. FREE with any order over $20.00 (offer expires S100 PROTO BOARD April 15, 1978). $19.50 Pack and Postage $1.00 SC/MP ON 5100 CARD S100 MOTHER BOARD Interested in expanding your Miniscamp to a more useful system? This handy PCB. makes it possible to This 8 slot S100 Mother Board will greatly simplify connect the SC/MP (N or P Channel) to the hobby construction of your S100 system. Has provision for standard S100 buss. Has provision for Xtal clock and power distribution and bypass capacitors. Also full buffering of the chip, and of course on -card re- accepts 16 PIN DIL connections to adapt to other gulators. Board is quality fibre glass tin plated systems. top with hard gold S100 edge fingers. S100 MOTHER BOARD S100/SCMP BOARD $ 22.50 Pack and Postage $1.00 $19.50 Pack and Postage $1.00

1.3 bankcary POSTAL ADDRESS P.O. Box 355, Hornsby, 2077 1\r/ APPLIED welcome here TECHNOLOGY SHOWROOM 109-111 Hunter St., ,Hornsby 2077 (9-5 Monday to Sat) PTY. LTD. PHONE 476 4758 - 476 3759 lop or PLEASE USE BLOCK LETTERS

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For Sale: Half Price. ETI, EA, PW, PE, EE, oscilloscope for hobby and experimental Experienced programmer available for APL or (Magazine). Write to Dan Hackett, 7 Massey work for matriculation physics. Grant BASIC. Terms are negotiable. Send St, Rossmoyne, WA 6155. Any price accepted. Reynolds, 33 Hartington St, Glenroy, requirements to David Newell, 36 Gladstone Victoria 3046. Road, Prospect, SA 5082 or phone (08) 44 Sell: Hewlett Packard counter, all valves, 100 9303 (AH) kHz crystal oven, cooling fan, large size 18 x Wanted, backcopies ETI Oct, Nov, 76, Sept 75, 17 x 10 (in), ideal computer system home. EA Aug, May 77. Valve transformer, A & R SELL, High class COI. Constant 0/P with $30 Ph. 337 2317 Sydney. 2624 or equivalent. J. Philp, 50 Quay St, 5 - 24 V I/P. Fully encapsulated. Provision Brisbane 4000. for adjusting' timing. Enquiries: G. IBM Selectric typewriter with I/O interface Younghusband, P.O. Box 191, Laverton, $150. 5" CRT monitor $50. Paper tape reader Sell: 2650 KT9500 ass. and tested, ETI 632 VIC 3028. Ph 399 1568 mechanics only $15. All suit microprocessor. VDU, plus other items. 498 6950 after 6 pm. Sydney 419 2839. Wanted: circuit diagram 'for the 'Atar' Star Electronic Technician Certificate Students Wars game. R. Dyball, 39 Greenhills Ave, Miniscamp microprocessor power supply and (Stage 1, SA) Physics -Genzer, Younger; Woodberry, 2322. Ph (049) 66 2869. frame included. Full documentatiop. Ideal for in new condition for sale. $17.50. Mike learner or as an extra controller $100. Phone Springett, Ph (08) 356.5010. Zeners 1000 BZX 75C 1V4 $30. 200 WZ22V (02) 439 7270 after 4 pm weekdays. $10 Pr. Spkrs. Plessey/Philips 3 way X -over Sell: 'Australian Official Radio Service unused, cost $250, sell $100. Buckley, 53 2650 computer, fully buffered, 4K RAM, Manual', 1938 and 1947, $3 ea. 'Radio Merino Cresc., Airds, 2650. (046) 25 7175 number cruncher board, with power supply, Diagram and IF Index', 1948, $1. All plus I/O board, graphics board and vector display, postage. Meissner, 262 Pickering St, Wanted: Practical Electronics, Oct 76, Nov software. $600. A. Peek, 10 Gale St, Gaythorne, 4051. Ph. (07) 355 - 3443. 76, Dec 76, Jan 77, Feb 77. Peter Anderson, Woolwich, 2110. (02) 89 1450. P.O. Box 209, Lakes Entrance, VIC 3909. Wanted: Constructional plans for 27-29 MHz Sell two Auditec 100 W RMS power amplifiers 4 -8 channel digital proportional radio control Texas Instruments SR52 224 -steps pro- with mains transformer capacitors. Never used system, 1 mile range, for standard servos. grammable calculator with magnetic card $110 or offer. J. Barbour, Brisbane. (07) G. Solomon, (02) 747 2603. storage for sale $175. Tony McGetj, P.O. 229 2650, 10 - 6 pm. Box 14, Gloucester 2422. Ph 460 (work). Repertory Theatre Company needs used Wanted: Mother board for microprocessor electronic dimmer set, not necessarily (e.g. PDP-11 Unibus) or good quality edge working. Write with price and particulars. connectors. Contact Steven Cornelius, Main R. Horstman, 25 leichhart St, Toowoomba, Road, Rokeby 7019, Tasmania or phone 4350 Old. (002) 478893. Wanted:Practical Electronics, Oct 71 in good Sell: Playmaster Stereo Cassette deck. condition. Will pay $2.00. S. Campbell, Complete except R/P head and chassis. PCB 25 Buck master Dr., Mill Park, Vic. Ph. 404 assembled but not tested, $75 o.n.o. 2331. send your ad to A. Burgess, 130 Brackenbury St, Warrandyte, - 3113. Decca 'London' cartridge. Little used since ETI MiniMart, overhaul by makers. $35 or reasonable offer. Modern Magazines, Canadian QSL swap club, new members 'Aldridge, 12 Marcel St, Heatley, Townsville. welcome. Please write to C.Q.S.C., Box 251, Ph. 73 2937. 15 Boundary Street, Plympton, SA 5038 for membership form. Rushcutters For Sale: complete CB to Novice amateur Bay, Sell Trio 75 mm oscilloscope, 10 mV/div, licence conversion course - theory, questions, NSW 2011. DC-5MHz, very good condition, $110. morse tapes. $15.00 posted. D. Wilson, With test leads, handbook. Richard Samuel, VK2NMW, 63 Superior Av, Seven Hills 2147. Melbourne 96 5773, leave message. Amateur Radio Novice Course in Sydney at Wanted: Student requires reasonably cheap Hornsby. Discover the real thing. Contact Barry White on (02) 487 1428.

66 ELECTRONICS TODAY INTERNATIONAL - MARCH 1978 ETI data sheet NLS 4944 UNIVERSAL LED NATIONAL THE NSL4944 IS A simple two -lead device normally used as an AC or DC Features indicator whch can also be used as a Supply range 2 V to 18 V rectifier and constant current source Reverse polarity protection at the same time in associated Constant light output over 3 V :TO 01111A 111 normal LED circuitry. Further, most of the No larger than SU PP regulating circuitry is not in series 110 12mA to 14 mA current with the LED. This allows the 300 mW dissipation FIGURE 3. AC Power complete regulated LED to operate at Low cost per unit only about 300 mV more than a standard red LED. Thus the NSL4944 Schematic operates on half the voltage needed Figure 2 shows how some of the by previously available regulated or operating features of the device are resistor LEDs. The device is rated for a achieved. The rectifying characteristic maximum of 18 V forward and occurs because the only input to the reverse. device passes through the IC's PNP These characteristics provide seve- emitters. These have a high reverse FIGURE 4. Unfiltered DC Power ral advantages. Unloaded TTL gates voltage in standard linear processing millisecond. In both situations, the provide enough voltage, in either high The voltage reference and compari- or low states, to directly drive the indicator may be switched a number universal indicator. Size and weight of ways, including bipolar transistors, DC pass can be saved in instruments with a since only can through the number of indicator lights by reducing indicator. the size of filter capacitors or voltage Full Intensity regulators. The NSL4944 can operate AS shown in Fig. 5, full intensity on unfiltered DC or at somewhat and zero possible flicker are achieved intensity on 3 to 12 VAC. reduced C MPARIs011 by minimal DC filtering. The small A met If II R Since the IC within the regulated LED capacitor shown operates with 10 V blocks reverse voltage, the device can p -p ripple and only about 8 V average be used as a low voltage rectifier or DC, while the constant current drain polarity indicator. NSL FIGURE 2 Schemata Diagram characteristics of the 4944 allow son amplifier operate from the same low voltage that the LED does. The big Equivalent Circuit PNP transistor which passes both ICED and IREF can be operated almost in the comparison tvP11.A saturation since amplifier can pull the PNP base down 10 VAC to only one volt from common. FIGURE 5. Minimizing DC Filtering Unfiltered AC only a few percent change in light Power and parts count is minimiz- intensity. If a system or instrument ed by powering the indicator from a with a regulated supply has a number (WIVE UEA0 WIDER AT EASE low voltage transformer winding as of LED indicators, regulator size' and OF PACKAGE shown in Fig. 3. This method, dissipation can be minimized by FIGURE 1. Equivalent Circuit however, provides only half intensity powering the regulated LEDs from the light, but the apparent visual decrease unregulated voltage. is not as great. Some flicker occurs if moves his head rapidly. The LED and its current source, as the observer The supply of Fig. 4 will provide up Reduced Intensity illustrated in Fig. 1, both fit within a maximum light output. The The low operating voltage and standard LED package. The typical to 87% of make operating voltages shown allow the bulk of a filter capacitor is still not constant current characteristics flicker will LED an ideal status device to operate with lower supplies needed, and at 12 VAC in, the regulated An and take up less room than an LED be almost imperceptible since the LED indicator for digital circuitry. less than a interesting fact to keep in mind is that and resistor. ""off" periods will be

67 ELECTRONICS TODAY INTERNATIONAL - MARCH 1978 ETI data sheet full regulator current is not needed to light the LED. If, for example, only 8 SIGMASfNSIIIVE RELAY -0afnA mA is available (from a voltage of 1.6 C 110010 to 1.9 V) the LED T will light at a 1S I 110 VAC 6.1 -6V somewhat reduced intensity. The VAC BATTERY I regulator will be switched full on instead of current limiting ... but in SMALL BATTERY TRICKLE CHASSES such a situation it doesn't matter.

FIGURE 9. Six Second Time Daley TTL Drive current when the relay reaches its 11 Any circuit capable of supplying V pull -in voltage. The 14 to 18 V 10 to 20 mA and a voltage swing of at supply variation will produce only about a least 1 V can switch the NSL4944 3% timing variation, a from an off to an on state Fig 6a, b. considerable improvement. Varia- Within 25°C of room temperature, an tions due to temperature and electro- input voltage of 1.3V will produce lytic capacitor tolerances will remain little or no V however. light, and 2.3 will SNORTED SCR INDICATOR A number of LEDs can "share" a produce 70% to 90% of full output. B However, with a small signal change, single constant current LED. Further, the pre-existing biases must be any of the ordinary LEDs can be FIGURE 7. correct. The output swing of a TTL turned on and off by a shunting switch without stage goes much closer to ground Shortproof Circuit affecting operation of any of than to the 5 V supply. the others. A current source can also be a S VOC Active Loads current limiter. Fig. 8 shows an The lamp -driver Schmitt of Fig 10 NSL4944 put in the collector of an illustrates a still further use of the emitter follower such as might be NSL4944's constant current source. used in a pre-amp or mike mixer cable driver. Substituting a current source for the ISV collector resistor increases the useful voltage gain of Q1. Further, almost full base current remains available to Q2, A even when supplying 12 V output, Low Indicator which would not be possible using a IN resistor. When the lamp and Q2 are .11v off, most of the LED current flows in 1S TO ADQIO CABLE ETC

FIGURE 8. Current Limiting and Short Protection Normally voltage across the LED is (3) LAMP.DRIVING only 2 V, allowing almost full fCNMITTS B High Indicator supply -to -supply swing of the emitter Combination follower output. In comparison a 1T V LAMES TO I AMPERE limiting resistor would either greatly FIGURE 6. TTL Indicators increase output impedance, or seve- IRIGM POWER Su1stlTutIDN1 Therefore, Fig. 6-C requires a 3.5 V rely limit output swing. However, if supply for the indicators to have the output cable is accidentally. FIGURE 10. Use as Activa Load complete off -on switching. .shorted, only a little more than the the 100 R resistor, thus determining Replacing FETs rated current of the LED will flow. Output transistor the circuit's switching or trip point of dissipation actually 2 V. In many circuits or small instru- decreases under emitter short condi- With Q1 saturated, Q2 still provides ments the need for a constant tions. current a volt to the bulb, contributing source or current limiter arises. some FETs Delay Tactics preheating and reducing the bulb's can generally only be used as low Logically, a constant current starting current surge. On, current sources, so for 10 mA or more Q2 source is helpful in designing time provides the bulb with 12 V due to parts. If an indicator or pilot light is the delay circuits. If the circuit of Fig. 9 minimum voltage drop in the constant also needed, the regulated LED may were built with a resistor, the current LED. The 6k8 feedback be a very economical source of the timing period would only be half the resistor sets hysteresis a heeded constant current. at measured amount shown, and timing would 50 mV at the input. This The examples below illustrate can be varied all vary over 50% with the supply without having three characteristics of the NSL4944. to change the rest of variations shown. the circuit. 10k provides almost It is a combined rectifier, constant Instead, the current regulated LED hysteresis (undesirable and unstable) current source, and pilot light. is still drawing within 10% of full while 2k sets a hysteresis of 0.5 V.

68 ELECTRONICS TODAY INTERNATIONAL - MARCH 1978

INTERNATIONAL

electronics TEST GEAR it s easy ELECTRONICS IT'S EASY TEST GEAR Metering and power supply Vol 1/2/3. ,,metering and ewer supply protects projects. ta o ur Available from newsagents or Volumes 1 & 2 now reprinted directly from Electronics Today as a second edition! audio ed111voltoeter International. Published in June Muylti] d Y.pley digital olbTter 1977. Contains Audio Level Vol 1. The first 12 parts of simple frequency counter Meter, Audio ¡elk phase eater Meter, Impedance this very successful series audio signal generator Millivoltmeter, Simple Frequency produced as a 100 page book. s gcttsusloio Countér, Phase Meter, Temp- This volume takes the reader 1C testers five parer supplies erature Meter, Audio Signal Compnw. an to decade resistance boa D.+pary 4snserm from introduction Generator, Audio Noise ts.g.tr r.ntrs.r..«r stone calibrator T,,..e .... o LIMY electronics through to bean adaptor , Generator, Tone Burst Generator, Sc nree a n.en.e..s operational amplifiers. silent A -B snitch Corot red of Pow. audio attenuator Cross Hatch/Dot Generator, RF Vol 2. The 'middle -third' universal titer Signal Generator, Marker --N of the series introduces the Logic Probe, Logic TOW pubwdpn Generator, reader to more sophisticated yr an nbclRolecs Pulser, Logic Tester, Simple techniques, and includes CMOS Tester, Transistor Tester, power supplies, waveforms, filters and logic systems. Linear IC Tester, IC Power Supply, Dual Power Supply, Basic Power Vol 3. The final volume covers digital displays and systems, Supply, Experimenter's Power Supply, Switching Regulator Supply, computers, transmission systems. instrumentation and the Decade Resistance Box, Oscilloscope Calibrator, Dual Beam control of power. Adaptor, Silent A -B Switch, Audio Attenuator, Universal Timer. $3.00 per volume plus 40 cents per volume post and packing $3.00 plus 40 cents post and packing! (60 cents post and packing total if two or three volumes ordered at the same time.) Volume TOP PROJECTS Vol 3 newsagents or TOP PROJECTS Vol 4 TOP Available from AUDIO EXPANDER COMPRESSOR. Electronics MODULES. directly from 50-100 WATT AMPLIFIER Available from newsagents or PROJECTS Today International. -GAME. rom Eleclron,cs Today 3230 AUDIO LIMITER. SELECTA directly from Electronics in October 1976. .,,- Published AUDIO PHASER. `T' - Today International. Published Contains FM Tuner, 25 Watt in June 1977. Contains Audio Amplifier, Active Crossover, Top Expander/Compressor, 50-100 Crossover Amplifier, Booster IOJECTS watt Amp Modules, Stereo Amplifier, 50 Watt Power Ire Amplifier, Dynamic Noise System, today $3e00 Module, 400 Speaker V0[.4 electronics Filter, Audio Phaser, Audio Audio'Noise Generator, Cross- r *-11. ALARM. TRAIN Limiter, TV Game, Swimming hatch/Dot Generator, ETI CONTROLLER. ACTIVE ANTENNA. Pool Alarm, Temperature Utiliboard, Linear IC Tester, GSR MONITOR. DYNAMIC NOISE Alarm, Active Antenna, GSR Dual Beam Adaptor, FILTER. SELECTA-GAME. 'SCOPE Monitor, Universal Timer, ;'i::1 Impedance Meter, Tone TEST YOUR CAR. TEMPERATURE Mini -Organ, GP Power Supply, Burst Generator, Digital METER. UNIVERSAL TIMER. KITS Temperature Meter, Train Display, Digital Voltmeter, Testing. FOR ETI PROJECTS. 50-100 WATT Controller, Car 'Scope L $3.00 plus 40 cents post and AMPLIFIER MODULES. GENERAL Frequency Logic Probe, Logic Pulser, Switching Regulator packing. Counter, PURPOSE POWER SUPPLY. AUDIO Supply, Nickel Cadmium Battery Charger, Radar Intruder Alarm, Al ADM I IMITFD TFMDFDATIIDF Intruder Alarm, Colour Organ, Car Alarm, Transistor Connections. $2.50 plus 40 cents postage and packing. INTERNATIONAL 3600 s12 so AND 4600 SYNTHESIZERS Projects Vols 1 and A totally revised and updated We regret that due to heavy demand, Top reprint of ETI's phenomenally 2 are no longer available. successful music synthesizer International book. This book has been beautifully 3600 and 4600 - printed on heavy art paper and HOW TO ORDER has a sturdy cover varnished Synthesizers It's Easy series protection. Top Projects Vols. 3 and 4, the Electronics for most newsagents Available only from ETI and and the Test Gear book are available from some kit set suppliers $12.50 or directly from ETI. including postage and packing. The Synthesizer book is available only from us and a limited number of specialist suppliers - it is not sold by newsagents. NSend orders to Electronics Today International 15 Boundary Street Rushcutters Bay 1101 s MODERN M AGA ZINES publication NSW 2011

69 ELECTRONICS TODAY INTERNATIONAL - MARCH 1978 106A HAMPDEN RD, ELECTROCRAFT PTY LTD ARTARMON 2064 PHONE: 411-2989 E CRAFT TELEVISION AERIAL AND DISTRIBUTION EQUIPMENT 411-3772 CB RADIOS, AERIALS & ACCESSORIES

TELEVISION AERIAL HARDWARE: Wall brackets. ECRAFT DISTRIBUTION AMPLIFIERS chimney mounts. U brackets, guy wire. guy AND AMPLIFIER SPUTTERS rings. masts from 8ft to 50ft. Medium and high gain distribution r TRANSCEIVERS amplifiers for 811 suitable applications Clearance sale of all our CB Radio stock to with 1. 2. 3 and4 1t., outputs suitable p;C -- make way for new shipment: for small' home unit, showroom COBRA 21 x DEGAUSSING COILS TRANSCEIVERS, COBRA or household type installations. complete with power 19M TRANSCEIVERS, PRESIDENT TYPE 1.75 DI has one output, 16 db gain cord plug and push button switch S14.00. "GRANT" AM/SSB. with low N/F Ready for use. $45.50 MOBILE AERIALS: Royce, Belling Lee Gilco WHILE TYPE 4.75 T19 has 4 outputs 19db CB EQUIPMENT of (heavy duty) topix. ACCESSORIES: Plugs. gain with low N/F 561.84 h WAVE SPIRAL TUNED BASE STATION sockets, jumper leads, coaxial cable SWR ANTENNAS AERIAL. Meters, etc. ALL TYPES OF CABLE: in stock, A COMPLETE RANGE OF TV & FM AERIALS. Omnidirectional (top view) coaxial. twin, 300. 75. 850. From 30 cents per HILLS CHANNEL MASTER. MATCHMASTER radiation pattern with ex- metre. & cellent ground wave and H1.0. '"t.- HILLS sky wave characteristics. r,_ CA16 - High gain phase array 45.94 Ideal for "Point to Point" 215.2710 - 8 element yagi 25.29 & '"Skip" com- qC` 2010.2710 - Airways screened munications. Sturdy COMPONENTS co plated base bracket, 4 -linear 58.26 FCRGUSON TRANSFORMERS EFC 1 75 for telescopic radials and ver- - colour low gain 36.00 240V to 18V 60VA (Low profile) FC2 tical radiator. Spiral tuning $8.95' - 75 for colour medium gain 56.96 240V to 18V 20VA (Low profile) EFC 75 for stub at base for quick and 56.55' 3 - colour high gain 75.50 240V to 18V.0 18V (PC 5A Type) 54.56' ' CHANNEL easy tuning. SWR of 1.1 1 possible. Aerial MASTER PLUG TYPE POWER PACKS 3110 2 coloray comes complete with 50 239 socket. U bolt - element 27.96 240V to 18V DC, Full wave rectification. 3111 6 element super coloray 41.98 and saddle and detailed instruction sheet. - 470LF Filter capacitor: c/W 1 metre lead & H1.Q.LOG PERIODICS 537.75' - - 3.5mm plug $5.50' ' 8 element & 10 elements 539.00 (Excellent METAL BOXES back to front ratio). L=200mm. W=135mm. H=70mm Black ACCESSORIES: Outlet plates. <" Transformer DELIVERY ARRANGED IN SYDNEY AREA Vinyl covered, suitable for CB Power supply. splatters. Attenuators, filters, plugs, sockets for etc., ideal project box $3.50' ' . 75 ohm x 300 ohm applications. FOR ORDERS OVER $ 10.00 "RECOMMENDED RETAIL PRICE (NSW)

Terrace, -PTY LTD-I BRISBANE 1 Wickham Brisbane. CONTROL KNOBS. Also 35 Logan Road, Woollongabba SCREW FIX Queensland Distributors for Swann DEL OUND 1 229-6,55 Electronics (ex Murdo) I.C. TEST CLIPS JACK PLUGS I, .

14/16 PIN $4.60 28 PIN $9.50 40 PIN $11.90

11 i INSULATED ' TERMINALS PRICE LIST FOR CLIFF KNOBS TERMINAL PLUGS K1 Black/Grey 28c P2, MONO 6.3mm TOUGH MOULDED COVER50c K1 Black/Grey Chrome Top 34c ASSORTED COLOURS K1 Black/Grey Coloured Anodised Top 34c P5, MONO METAL 3.5mm 40c K2 Black/Grey Chrome Top 40c SEP3 MONO METAL COVER 95c K2 Black/Grey Plain 29c JACK SOCKETS (Nylon) K2 Black/Grey Coloured Anodised Top 48c S1-MONO, CHASSIS INSULATED 35c K3 Black/Grey ' 28c K4 S3-STEREO, CHASSIS INSULATED 57c Black/Grey 29c K5 Black/Grey 49c S5-MONO, CHASSIS METAL FACIA NUT 60C K5 Black/Grey Marker Line 54c MAIL ORDERS & TRADE K6 Black/Grey 54c ENQUIRIES WELCOME K6 Black/Grey Marker Dot 56c TP1 $ TP2 45c K6 Black/Grey Skirt 0-10 76c STOCKS AS OF 1/10/77 P12 (2mm) THROUGH PLUG 15c K7 Black/Grey 54c ALL PRICES PLUS 10% POST & PACK K7 P14 (4mm) TOP BANANA PLUG 22c Black/Grey Marker Line 56c CBs & ACCESSORIES 411~. K8 Black/Grey .48c .a AUSTRALIA'S SEM ICON DUCTOR SPECIALIST ANNOUNCES

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IAN SINCLAIR'S NEW SERIES IS DESIGNED TO IMPART THEORETICAL KNOWLEDGE THROUGH SIMPLE PRACTICAL EXPERIMENTS

MANY EXPERIENCED Constructors rail. For our course on digital electronics with several acres of transistor circuits The ICs we shall use in this course we shall need seven digital ICs and one behind them still fight a little shy of will be from the well-known TTL series, "jumbo" display, a full inventory of using digital integrated circuits. The developed by Texas, and also available semiconductors being shown in Table 1, need a reasons for this are not difficult to see. from several other manufacturers. There and in addition we shall also few Most of the transistor circuits with are several reasons for this: the devices other assorted components. Where a 5 V which an experimenter learns his are readily available at very low prices, supply is not available, a stabiliser can trade are fairly simple and show rather advertised in ETI and they are much less be included on the board, 'so that the be using a well how a transistor works, giving a easily damaged electrically than the experiments can carried out feeling of confidence to the user. alternative CMOS. car battery or any DC supply in the 6 V The many excellent projects using to 12 V range. Note that the current digital integrated circuits which have 0/C Inputs taken will be up to 350 mA. been published do not give any such When an input of a TTL gate is left help to the constructor, however. They open -circuit it automatically reverts to Breadboard is may be comparatively easy to build a "1". The reason for this is that the The heart of the whole project the the iCs and all on a prepared PCB, they may even be input to TTL gates is to one emitter of circuit board on which reasonably easy to understand, but they a multiple -emitter transistor whose other components can be mounted. do not give the constructor the exper- base is connected 'through a limiting This is one of the series of "Blob ience which enables him to design resistor to the +5 V line. Leaving an Boards" advertised in ETI - in this case confidently with ICs. input o/c means that the emitter the ZB-8-IC. Blob Boards consist of This series is intended to remedy terminal will take up the same voltage wide strips of tinned copper on the main that deficiency, so that the reader will as the base terminal. This cannot be usual insulating board, and their is are gain a firm grasp of the principles of done when CMOS devices are used. feature that components mounted digital IC behaviour, how they work, on the same side of the board as the and also a considerable amount of strips. "hands-on" experience on a board This, of course, is not a new principle designed to' make experimenting with in digital IC construction, since this digital ICs particularly easy. We shall method has been used for some time confine ourselves to the smaller scale where digital ICs are mounted on ICs so that nothing at involved as a double -sided boards. microprocessor will be used - the The ZB-8-IC as its name suggests, has components however are chosen so that mounting pads for eight ICs, including have specified. they give a good range of experience the display which we with some useful devices. The suggested layout for the ICs is shown in Fig. 3, where we can see that One and none the top left hand corner houses the We can assume that any reader of ETI 7414 Schmitt inverters and the 7400 will already have some knowledge of Nand gate; the top right hand corner what digital circuits are about, but has the two 7476 J -K flip-flops. At the hand we have a perhaps a very brief reminder may be bottom left corner, decade of some use. Digital ICs are made up 7494 shift register and the 7490 counter. The bottom right hand corner from transistor circuits of very high gain, Fig.1. The method of attaching compon- designed to run with inputs and outputs ents to the Blob Boards. The 'leg' can contains the 7447 BCD -7 segment which take up one of two states which be simply bent to one side and then sol- decoder -driver and the display. All of dered 'blobed' over the lead to hold it. the ICs have conventional DI L fourteen we call 1 and O. In most applications, 0 tinned, and the leg Since the boards are or sixteen pin bases, but the display has will mean a voltage very near to earth ought to be, a sound joint is usually .a base which is an eighteen pin type potential, and 1 near to the full supply obtained.

ELECTRONICS TODAY INTERNATIONAL - MARCH 1978 73 with several pins omitted, so that this Digital Electronics will just fit the pads on the board. The spacing between the lines of pins (0.6") is a little on the large side compared to By Experiment the other ICs, but with care it can be accommodated. In the circuits which we are using we shall not normally need the decimal point' on the display, but its connection may as well be made just in case. Before any experiments are started then, it is advisable to solder all the ICs and the display on to the board, so . that this does not have to be done when 2 "r- it becomes cluttered by other components. Since each circuit mounts on to _pads which are isolated unless 5 II I 6 _1 1_.I II I= other are connections made, no harm:is 7 done by leaving an IC soldered on to the - 4:1 _. board. 10 =1tr It is for this reason, incidentally, that 11 f is 12 it not desirable to use CMOS circuits 13 in such a project, since the protection 14 diodes built into CMOS ICs will operate 15 only when the 16 I _ power supplies are 17 =11 _I connected. 18 In the prototype, the lines running 19 Isomi round the edge of the Blob -board were 20 used 21 I for supplies, the outer line taken as 22 I I the positive 5 V line, and the inner as 23 earth. It is quite 24 convenient also if the 25 =1tif shorter lines running across the board between. each pair of IC pads are also 27 1 28 used as and 0 lines as well. The vertical 29 lines at the centre of the board may also 30 be used. If a regulated 5 V is 31 supply 32 available for operating the board then 33 II little else needs to be done other than 34 connecting the power pack to the lines 311i V u R TS D PON K 3 I 14 c F FD CRA at the edge of the board. Fig. 2. Above: This is the track pattern for the ZB-8-IC used in this series. NoteI the wire links which need to be made in order mare easily facilitate application. Fig. 3. Be/ow: Components in place on the board. Note that unlike our usual overlays, the tracks are on the SAME side as the components. Fig.4. The layout for the digital TTL series. This is looking down at the device 2 from above. Usually, but NOT always 3 power is applied to pin 14 and pin 7 is earthed. 5 Fig.5. Bottom: Positioning the ICs onto 6 Blob -Board pads. Make shure the legs 7 line up.

9 PIN 14 PIN 8 10

12 414 7400 7476 707F 13

14 INDEX 15 MARK 16 17

19 19 20 21 22 6C 6F 23 74 7C 7F 25 26 8C 8F 27 9C 1^ 28 7494 7490 9F 7147 7 7 DISPLAY 29 30 10C 1OF 31 32 11C 11F 33 34 12C 12F

K W S R 0 14 D K D C 9 A 13C 13F

74 ELECTRONICS TODAY INTERNATIONAL - MARCH 1978 these are very useful for mounting com- Regulation ponents such as LEDs, which are used is not available, If a regulated supply to indicate the stag (0 or 1) of any out- can be constructed, however a regulator put. Note that on most LEDs there is a separate board, or onto the either on a flat portion of the plastic case near the A 7805 monolithic Blob-board itself. leadout wires which indicates which IC, with 10 µF tantalum cap- regulator leadout wire is the cathode. Since we to ground and out- acitors from input are using the LEDs to light on .a "1" can easily be mounted on put to ground, state, the cathode of each LED is J, K, and N (with the centre tracks FLAT connected to earth, and the anode N as input). PORTION a limiting resistor to the IC out- important that TTL through It is extremely put. This resistor value is higher than we not be operated at volt- circuits should would normally use, but suits this appli- above 5.25 V AT ANY TIME, since ages cation, as we do not want the LEDS to to TTL circuits are to the the inputs draw too much current from the IC transistors, with the bases emitters of When we come to use the the positive supply. If k a outputs. connected to shall also use large value are earthed, has display, we the inputs to the emitters Fig.6. ¡dentifing LED connections - of doubt limiting resistors. too much current will flow in the base caused many a paralysed moment one present With all the ICs mounted in place, emitter junctions, though if all the inputs - look for the flat bit, if there's problems are over. we are ready to start our work on earthed, over -voltage is much less then your are Digital Electronics By Experiment, with likely to cause damage. in next short pads, usually the first set of experiments about the board there are several Led and two vertical, and month's issue. Above and below each mounting pad three horizontal BOARD Note: Only the essential basic components OTHER COMPONENTS 1 ZB-8-IC Blob -Board listed here. For various additional 1 x 0.1uF are this suggested experiments, additional resistors 1 x 1.0uF For a few applications in later parts of and capacitors will be needed; these 1x10uF series, a silicon NPN transistor may be some long values will be critical. 1 x 100u F used as an alternative to a reset SEMICONDUCTORS 1 x 680u F stretches of wiring (to connect 1 x 1000u F terminal on a counter). For this appli- 1 x SN7414N All the above 10V working, or more. any working small signal type is 1 x SN7400N cation, resistors, 0.125W or more 2 x SN7476N 10 x 470R suitable. 6 Miniature push-button switches. 1 x SN7494N 5 metres of single -core wire. 1 x SN7490N 1 x SN7447N 1 x 747 Display

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PRICE (KIT) $97.75 incl. sales tax SPECIFICATIONS: PRICE (FACTORY ASSEMBLED AND TESTED )$129.75 DC volts in 5 ranges: 100uV to 1000V; AC volts in 5 incl. sales tax to 1000V; DC current in 6 ranges: 10n range: 100uV ABOVE PRICES INCLUDE DELIVERY WITHIN AUSTRALIA A to 2A; AC current in 6 ranges: 10n A to 2A; Resis- tance in 6 ranges: 1 to 20M; Input Impedance: 10M; Display: 9mm (36") LED; Power requirements: 4.5 AUSTRALIAN AGENTS: 8 COMMUNICATION DEVICES VOC to 6.4 VDC (4 "C" cells-not included); Size: NSW 2010. "W" x 6.5" D x 3.0"H (203W x 165D x 76H mm). 271 Goulburn St, Darlinghurst, Phone: 2113399, 2113652, 2123712.

75 ELECTRONICS TODAY INTERNATIONAL - MARCH 1978 MAD MARCH SALE .. . ATTENTION Battery Holders CL7 Red goer lfps and Black. SCHOOLS 9c ea. Xtal Set type tuning BH6 1/ s condenser tl complete with Penlight 6 cell rfial. CL1O Good old can be soldered everyday crocodile , naall ` it or use the .M clip. 95c t .l+ rev clips on top. 9c ea. Only BH 11 Mono Xtal 45c ea. Penlight 3 cell CL11 Fahnstock Clip. for 4.5V or join Ideal to patch up oscL Cartridge two up for 9V circuits. it:m=1s BSR type X5H $3.00 Qom 800mW. . 10c 4 35c ea. ea. Stereo CL12 Robust BH9 935 6 cell. Ideal plastic -covered. Ceramic I M for heavier applications Red and Black. As used in many Japanese where there is room. units. BSR type SC7M-4 40c ea. $3.95 ea. Only 50c ea. SIGNAL MES EARPIECES Lampholder GENERATOR LH3 H5 8 ohm complete with Suits our 6, 12, KITSET 3.5 mm dug. What more can we say for only 24V liour lamps. 50c ea. 10c ea. H6 High hoped. for Xtal sets. sig. generators. etc. 96c ea. Fuses Standard 1W"" 3AG . 250, 500, 750mA 10c ea. WOW! Inject audio signals into for 1, We've had some circuits fault finding. Also 2.5 amp 6c ea. trace audio signals. The perfect kitset for the begin- a microphone specials in ner. Kit comes 20 mm x 5 mm Standard complete except for 2 penlight cells. Comprehensive 400, 500mA .) the past but this one beats all. building Instructions are supplied. 1, 2.5. 3 amp 12c ea. Suits most cassette recorders. Complete 20 mm x 5 mm Sloblow Plugs and with plugs and Sockets 1. 2. 2.5. 3 amp 26c ea. stand. Polarised plug Hook-up Wire Tape Recorder CDM1631 and socket. i r P2 S2 Wafer Microphone Only $2,15 11) 7c ea. 9c ea. .2 mm2 (6 x 0.2 mm) Perfect to have on hand Suitable power supplies, etc. 4 A irt2J around the workshop. Comes in red, Black, .V TCA2EC/RHNT ICAL D ATA: and 5 pin. Green, Yellow, Blue,Orange, Grey, GUTTERGRIP R/T White P4 or 5 S4 or 5 51. per 15 metres Constructed In non-ferrous materials for AERIAL lasting beauty. All metals chrome plated. 8c ea. 9c ea. Spare partsiable.ncluding replacement cables Model CA2/RT for VHF readily acat Variable Capacitor operation Frequency range approx. 80 mkt -180 mHz S12 Ideal $6.25 V.S.W.R.-80mHr 1.1:1 combination.. 175 mHz, less than C1604 140F 1.1:1 2 pin p.Ets. ` . Sortable for VHF. and 5 J communications quip. Low 12c ea. P12 2 tolerance. pin plug $1.95 ea. n, Dwell Meter d. i. n. ,. .1111 Slider Knob 3 pin din. plugs and metal Kitset $6,60 We might as well give chassis sockets. Spare lamps 6.5V 3 these away at Complete kit less meter and case. Save amp. Tubular MES. this price. on service costs and keep your car in PL23 32c K25 20c ea. PHONO PLUGS good tune. Set ignition points accurately P22 with this easy -to Metal phono plug. -assemble kit. Meter Matches socket below. required is 1mA Kit featured in ADDITIONAL EA July '77. Mail Order POSTAL CHARGES Only 6c ea. Instructions Order value Charge We ss -- 59.99 Ni1 S24 regret that all' these Minimum P P 51.00 510- 524.99 50.50 Twin offers must end 30th April Orders over 59.99 must Include S25- 549.99 51.50 additional postal charges (see right). 550- 599.99 Socket 1978. 5250 , 5100 or more 54.00 45c DAVRED ELECTRONICS PTY. LTD. 104-106 King Street Newtown Sydney Australia P.O. Box 317 Newtown, N.S.W. 2042. THE NEW BREED IN ELECTRONICS SERVICE Telephone 516-3544 Prices are for any quantity 1-10.000. Obviously we may run out of some products Better fill your order out right now!

Potentiometers Rotary Switches 80c Plugs and Sockets Without switch SW2 2 pole 2 pos. ea. SW4 2 pole 4 pos. 25K Log All SW6 3 pole 4 pos. 250K Log r I 3.5 mm only SW7 4 pole 3 pos. Box Socket. 500K Log S60B Great for all selection projects. 1 meg Log 25 mm wafer. 6.5 mm shaft 14c ea. 2 meg Log an I - 5K Lin 35c 25K Lin ea. Mini - 500K Lin Sub -min 2.5 mm Jack. meg 11, push 2 Lin Slide S61 Blue, Yellow, Red, Black. DPDT. anodized lever. 14c ea. With switch Green, White. Only 40c ea. 5K Log LOOK Sw16 30 Ili 25K Log ONLY ea. 2.5 mm Jack. box type. 50K Log S61B 500K Log 65c ea 15c ea.

Dual without switch Sub -min. 3.5 mm Plugs 50K Lin SW23 100K Lin DP P62 250K Lin DT - --rn 27c ea. 500K Lin 75c ROCK ROCK ROCK 50K Log Quality 100K Log ea. All 40c ea. 2540K Log 500K Log S W24 SW26 SW28 SPST SPOT DPDT Speaker Sockets Toggle ° o Project Sockets Slider Pots u 60c 50c Polarised Sockets 10K Lin Single -s ea. ea. Q 571 2 pin 25K Lin Single ONLY 100K Lin Single Irridescent Only 23c ea. 250K Lin Single $1.10 ea. 500K Lin Single 50c Push P75A 10K Log Single ON/OFF Red, Black. Blue, Silver. Co -ax. Plugs 25K Log Single ea. SPDT ROTARY 100K Log Single 240V 4 amp Nowhere do you buy these at 65c ea. this price. 78c ea. Preset Pots PT8A Only 24c

500 ohm, 4K. 7K,10K,22K, Lock Up! 47K. Push OFF! Red. Black. Blue. White, Yellow. Co -ax. Sockets 22c ea. Momentary off. S75 Chassis type. 441 50c ea. .31 Only 30c ea W/W RESISTORS Rotary key witch. PHONO 1 watt 33, .47 ohm 12c ea. Suitable low voltage. CONNECTORS Project Transformer Terminals $3.00 ea. Plastic covered T15 T17 Sub -min. 2 screw Wafer 2 screw std. C8 500mA terminal. 34 x 13 terminal. Ideal for á . Pug and socket i t speakers etc. 51 x 19 9, 7.5, 6-0-6. 7.5, 9V. mm. 1 mm. Ú1111111\\19 Suits many projects and can supply up to 18V 22c ea. using both tappings. Hole spacing 65 mm. 20c ea. 35c ea. Dim. W 45 mm, H 45 mm. Transformer prices will have to rise soon Semiconductors so be in now. Save postage and call in personally if Price Price IN4004 .10 $6.60 you live in Sydney. You'll receive a AC 126 .66 IN4005 .10 AC 188 .01 .58 pleasant welcome. IN4006 .10 BA148 .40 RECORD CLEANER CLOTHS IF YOU HAVEN'T A COPY OF OUR MAIL B8105 .45 1544 .07 P.S.- 0A91 08 BC178B .14 Clean, crisp sound can only come from a clean ORDER CATALOGUE ASK FOR ONE. WOULD YOU SN7403N .30 BC 1798 .34 record. Choose a Davred cleaning cloth for BELIEVE NO CHARGE IF MAKING ANY PURCHASE. SM495AN .70 BC183LB .25 fully effective dust removal. SN7496N 51.30 BC1848 .14 SN74107N .50 BC 184C .14 ADDITIONAL POSTAL CHARGES SN76005N 51.60 85c ea.. Volume enquiries welcome Mail Order BC213B .14 Order value Charge BF594 TAA570 54.00 .20 TIC226D 51.33 Instructions 59.99 Nil BF595 .20 S5- TIP42A .88 28 pin d.i.I. BFR40 .30 Minimum P P S1.00 510-524.99 50.50 TIS58 .50 BFR80 .30 28 Pin IC sockets Orders over S9.99 must include 525 - 549.99 51.50 TIS52A .39 IN60 .09 Top quality blue 28 pin sockets. additional right) 550 599.99 52.50 TP4007AN .38 postal charges (see - IN4001 .10 5100 or more 54.00 TP4028AN 51.48 Buy in bulk now while stocks last. 55c ea. IN4002 .10 DAVRED ELECTRONICS PTY. LTD. 104-106 King Street Newtown Sydney Australia P.O. Box 317 Newtown, N.S.W. 2042. THE NEW BREED IN ELECTRONICS SERVICE Telephone 516-3544 Essential FULL ASCII UPPER/LOWER CASE Computers We Stock Accoutrements COMPUTER KEYBOARDS IMSAI 699. Used Guaranteed Working TEXAS INST SOL20 1095. Cromenco Z2 595. Lo Profile Sockets r,,a 1.11--- Apply II (16K) 1698. rrrrrrrrrrraMíani Compucolor 2750. Pin 1 10 100 735. rrrrrrri' PP .. Poly 88 8 .30 2.50 20.00 rrurr porrrrr r2 .. sre Xitan I 769. 14 .25 2.00 18.00 & "1I3li .-ni1 n . Vector Graphics 619. 16 .27 2.20 20.00 ftif imifm wing Alpha Micro System 1495. 18 .40 3.20 27.00 7MIR 20 80 6.00 40.00 L,niummuuma StitiIr 22 50 4.00 30.00 24 50 4.00 30.00 28 50 4.00 30.00 Single Supply + 5v @ 800 ma 40 50 4.00 30.00 Memory Modules We Stock Schematics Included Basic Keyboard 545.00 *Write for 1K Hp pricing SSM MB7200ns16K 525 Add: S5.00 for Upper Case Alpha Industrial N Systems 8K 229 510.00 for Numeric Keypad Common DB Series SPACEBYTE 16K Static 599 S5.00 Misc. Function Switch SSM MB7 450ns 8K 199 Connector S40.00 Metal Case w/bottom Vector Graphics 250ns 8K 269 S45.00 Metal with Walnut Ends 1 10 100* 51.50 Connector DB 9P 1.10 1.00 .80 52.00 for 10 Extra Switches DB 9S 1.50 1.40 1.15 DB15P 1.50 1.40 1.15 DB15S 2.25 2.00 1.75 COMPONENTS DIP Switches DB25P 2.25 2.00 1.80 COMPUTER DB25S 3.25 3.10 2.75 5848.Sepulveda Blvd., Van Nuys, CA 91411 (213) 786-7411 1 10 100 DC37P 2.50 4 1.85 1.65 2.95 2.75 4705 Artesia Blvd., Lawndale, CA 90260 (213) 370-4842 1.45 DC37S 4.90 4.50 4.00 5 1.85 1.65 1.45

DD5OP 3.90 3.50 3.25 B of A and MC Welcome 6 1.85 1.65 1.45 OD50S 6.50 6.00 5.40 Terms: Min order 510.00 7 2.00 1.80 1.60 add 52.00 P and H if order 525.00 8 2.20 1.90 1.70 We stock a complete line Post Paid US if U.P.S. plus over 525.00 9 2.30 2.10 1.75 of 7400, 74LS, 4000 CMOS All orders U.S. Currency 10 2.40 2.20 1.80 GET IT TOGETHER! COMPATIBILITY is the name of the game. TECHNICS named it! 4 Whether you're starting a music system or upgrading one. If you want outstanding specifications, as well as o..... 11 the latest advances in component technology and design. You want Technics components: The concept is -simple. Technics The execution is precise. See the latest The performance is range now! outstanding. Including, the astounding SB series speakers (left), the precise SL-2000 THE NAME IS turntable (above), and the all new pow- TECHNICS erful 7300 and 7700 amplifiers. Technics RON CHAPMAN HI-FI NEWCASTLES MAIL ORDER SPECIALIST - 880 HUNTER STREET, NEWCASTLE 2302. PHONE 69 2733. i Noting down music by computer

Literal transcription by a computer of a performance in standard musical notation. By P.Mars, Robert Gordon's Institute of Technology, Aberdeen.

REPRODUCING A MUSICAL SCORE During a performance any notes expression mathematically poses an trans- all expression marks automatically is not a new idea. The struck by mistake are, of course, unsolved problem; first version of an automated piano, in cribed, for the print-out is not governed must be added later .by the composer. allows a key to be specified the form of a pianista, was introduced by any law of musical tonality. Difficulty The system lines between involve changes more than a hundred years ago. Later might arise in drawing the but many compositions developments include the well-known the bars of the music because the in key and it is not practical to account pianola and the piano camera. Our own musician seldom sticks exactly to a for them 'on-line', during performance. research stemmed from an interest in strict enough tempo to follow a parti- This information must be added later, modern jazz piano. cular crotchets/minute count, so the 'off-line'. In spite of these limitations, the There is a tremendous scarcity of bar lines may be incorrectly placed. a literal original, accurate transcriptions of such However, if the performer does stay machine gives completely pitch and music. Many jazz pianists have had no within the constraint and tolerance of a transcription in terms of note classical training in music, and even specific count, the computer can draw time, making the system attractive as a device for those who have cannot spare the time bar lines quite simply. Unfortunately, potential labour-saving for the tedious work of transcribing. for some practical applications such as musicians. transcribing avant garde jazz, timing But the keyboards of the piano and We intend to add to the system in a piece modulates and may have organ are ideally suited to the computer. within the near future, to permit the original random variations. It is a reasonably simple matter to transcription to be edited with the aid A further disadvantage of the system arrange that every time a note is struck of a conventional visual display unit. is it offers little or no discrimination it is recorded, and to monitor accurately that The composer will be able to insert between which hand plays which note the times when they are struck. All the expression marks, rests and so on auto- note tails are drawn information can be recorded in the or set of notes. All matically. is made binary form of 1 and 0, that ís, the upwards and no distinction lower and upper hand in the language of the digital computer. between Fast print-out. For similar reasons, no rests Information can be monitored during a Recent work in conjunction with the are drawn; it is impossible, for a partic- performance by using an automatic well-known jazz pianist Oscar Peterson ular piece, to ascertain individual transcription unit and storing it in has shown that the transcription system voicings. Rests must be added by the digital form on a cassette recorder. It can cope with the fastest of jazz impro- composer after the automatic trans- can'then be processed by computer to visations. It is a relatively simple matter cription has been made. No expression produce a transcript, in musical to play back original transcriptions marks are incorporated automatically, notation, of the original keyboard under remote computer control, and either, because modelling musical performance. thereby provide an audio check on their The transcription unit samples the validity. It is also possible to include entire keyboard at a rate of, for semi -automatic composition. For example, 20 times/second throughout example, given a standard popular tune, the performance and the information the computer can be organised to play on pitch and timing of notes, after some the standard left-hand chord sequence manipulation, is recorded. No audio and generate jazz improvisation, super- frequency needs to be recorded; all that imposed on the original chord sequences. is wanted is digital information, so it For any chord, notes that obey the does not matter if the piano is out of standard harmonic laws can be randomly Every impro- tune or even if a dummy keyboard is selected for improvisation. used. visation so produced is original and the It is quite simple to connect the composer can simply select the most automatic transcription unit and cassette attractive; the automatic transcription recorder to any keyboard device, but system then produces a conventional although direct electrical connections music -notation output. can be made to electronic organs and Although the system was originally pianos, optical transducers are needed developed to solve problems associated jazz piano, it can obviously be to convert the key movements of ord- Transcription of Chopin's 'Prelude in C with inary pianos. minor', opus 28, No. 20. applied to all forms of keyboard music.

ELECTRONICS TODAY INTERNATIONAL - MARCH 1978 Self-resonance in capacitors

Roger Harrison has been plotting again - this time it's self -resonant frequency versus lead length of ceramic capacitors!

THE LEADS AND CONSTRUCTION decreases with increasing frequency. But capacitor of appropriate value and lead all of capacitors form an inductance in a real capacitor the series inductance length so that its series resonant which is effectively in series with the of the leads and construction causes the frequency is at, or close to, the capacitance of the component. The impedance of the capacitor to increase frequency in use. Series resonant combined effect forms a series resonant above the self -resonant frequency. bypasses do a better job. tuned circuit, the frequency which Within a range of 0.7 1.4 of to times this Alternatively, when selecting a bypass (the self -resonant frequency) is mainly frequency the impedance will be equal capacitor, always ensure that, for the dependant on the length of the to, or better than, the reactance of the value chosen, its series resonant connecting leads, .the pure construction of capacitance. frequency is above the highest the capacitor and the way it is mounted. One can make use of this characteristic frequency likely to be encountered in The impedance of an ideal capacitor in bypass applications by using a the circuit. This ensures that the impedance is always low over the frequency range of interest. There are other ways in which the FROM series resonance a POWER of capacitor can be AMPLIFIER L utilized. A pi -network, as is frequently used in the output stages of transmitters, is shown in Fig. 1. The output capacitor, C2, will have a value that depends on the frequency and the input/output impedances. The leads of this capacitor can be cut to length before installation so that the series CAN BE RESONATED resonant frequency of the capacitor falls Fig. 1. Pi-network. WITH APPROPRIATE LEAD on the second harmonic transmitter LENGTH AT AN frequency. Thus it acts as a trap of very UNWANTED FREQUENCY low impedance at this frequency. If the second and third harmonics are to be suppressed, two capacitors may be connected in parallel (their added values to equal the value of C2), and resonated at the frequencies of the two harmonics. DIP METER Other frequencies (such as spurious mixing products) may be suppressed in the same fashion provided each frequency is sufficiently separated. In interstage coupling applications, the coupling capacitor may be resonated to CAPACITOR UNDER TEST the frequency used. Mounting a bypass capacitor flat against a groundplane (i.e. metal chassis or printed circuit board LEAD ground plane) increases its series LENGTH SOLDER LEADS resonant frequency by about 5%-10%. INTO SMALL HOLES Adding 2 mm or 3 mm wide copper strips along the length of the wire leads Fig. 2. Finding the series of a capacitor can increase its series resonant frequency of a resonant frequency by 30%-40%. capacitor. COPPER PLATE The series resonant OR P C. BOARD frequency of a capacitor may be measured by soldering

80 ELECTRONICS TODAY INTERNATIONAL - MARCH 1978 ' TABLE 1. SERIES RESONANT FREQUENCIES OF VARIOUS CAPACITOR STYLES

Lead Lengths & Resonant Frequencies

Value Style & Size 25 mm 20 mm 12 mm 5mm 1 mm Bandwidth

100pF Hi -K disc ceramic, 5mm dia 80 MHz - 135 MHz 165 MHz 200 M H z Broad 100pF NPO disc ceramic, 20 mm dia 75 MHz - 105 MHz 130 MHz Narrow 100pF NPO tubular ceramic, 20 x 3 mm 69 MHz - 99 MHz 122 MHz Narrow 100pF Stacked mica 60 MHz - 95 MHz 120 MHz Narrow 470pF Lo K disc ceramic, 5 mm dia. 65 MHz 80 MHz 14- 0 MHz Narrow 470pF Hi -K disc ceramic, 7 mm dia. 40 MHz - 60 MHz - Broad 680pF Hi -K disc ceramic, 5 mm dia. - 40 MHz 53 MHz 74 MHz 9- 2 MHz Narrow 1000pF Hi -K disc ceramic, 5mm dia. 34 MHz 37 MHz 45 MHz 58 MHz 84 MHz Narrow 1000pF Hi -K disc ceramic, 20 mm dia. 25 MHz - 35 MHz 46 MHz Sharp 1000pF Plastic Film 'Greencap' 28 MHz 31 MHz 39 MHz 50 MHz 65 MHz Sharp to Broad 4.7nF Hi -K disc ceramic, 7 mm dia. - 18 MHz 22 MHz Broad 4.7nF Hi-K disc ceramic, 'Red cap', 5 mm -18 MHz 21 MHz 25 MHz 33 MHz Sharp to Broad 4.7nF Plastic Film 'Greencap' 13 MHz 15 MHz 18 MHz 26 MHz Sharp .01µF Hi-K tubular ceramic, 10 x 3 mm 8 MHz - 11 MHz 14 MHz Broad .01µF Hi -K disc ceramic, 10 mm dia. 13 MHz 15 MHz Broad .01µF Hi -K disc ceramic 'Redcap', 5 mm 10- .3 MHz 11.7 MHz 16 MHz 21 MHz 34 MHz Sharp to Broad .01pF Plastic Film 'Greencap' 9.3 MHz 10.8 MHz 13.5 MHz 18 MHz 22 MHz Sharp to Broad

1000pF Resin -sealed Button Mica, 10 mm dia. - - - 500 M H z Broad 1000pF Gold -sealed Button Mica, 10 mm dia. - - - 800 MHz Broad 1000pF Solder -in Ceramic Feedthrough - - - 400 M H z Broad 1000pF Screw -mount ceramic Feedthrough - - - 250 MHz Broad .082µF Resin -sealed Button Mica, 10 mm - - - 100 MHz Narrow

the leads to a relatively large copper good. choice for bypass applications into Button ceramics exhibit similar plate or piece of p.c. board, as shown in the middle VHF region. For characteristics. Note the high Fig.2, and finding the resonance with a applications to 60 MHz or so the self -resonant frequency of the 0.082pF grid -dip meter (gate -dip meter, or common, plastic film 'greencap' is quite button mica. base -dip meter for modern instruments). good along with various styles of The self -resonant frequency of disc Table 1 lists the series resonant ceramic capacitors. For stringent ceramics is dependent largely on its dia- frequencies of a variety of values, styles applications in the VHF -UHF region or meter and lead length. The graph in Fig. and sizes of capacitors. The lead lengths for effective bypassing over wide 3 illustrates this for a variety of disc noted are the lengths of each lead (refer bandwidths, the button mica capacitor ceramics and a stacked mica capacitor Fig.2), the disc ceramic is obviously a or ceramic feedthroughs are necessary. for comparison.

Fig. 3. Self -resonant frequency versus lead length for various diameter ceramic disc capacitors (after J. Bork, 'A note on the self-resonance of ceramic E capacitors; proc. I. R. E. (Aust) May 19571.

E E E Yá N

45 - min -.- LL-' LL Q Go z W O o 4-OQ 40 mm - - z > 35 mm -

30mm--Á

Á 25mm 12-4 -11 áE q 11 20 mm áFo ó 15 mm

10 mm

5mm "ir 240 40 60 80 100 120 140 160 180 200 220 FREQUENCY IN mHz. FIG 3

ELECTRONICS TODAY INTERNATIONAL - MARCH 1978 81 P.C. BOARD BRIGHTEST foz. Copper F/glass Lam SHOP AT MELBOURNE'S 8" x 2" 0.85 0.35 6" x 3" 1.00 0.40 6"x4" 1.20 0.50 ELECTRONICS OUTLET... 8"x4" 1.50 0.65

ZENERS 400mW 5% E24 Values 3V to 33V .20

RESISTORS IRVING'sROD I.R.H. Metal Glaze G.L.P. or G.L.%Watt 2.20 oclp HM to 1MEG 3 cents each or 2.5 cents for 100 plus. CB REGULATOR UA78CB 13.8V at 2A $2.60 e M' TRANSISTORS C BC107 .18 PN3565 .20 BC108 .18 PN3566 .20 499 HIGH ST., NORTHCOTE, VIC. 3070, PHONE (03) 489-8131 BC109 .18 PN3568 .20 BC547 .20 MJ2955 1.60 OR WRITE AND ORDER TO US AT P.O. BOX 135, NORTHCOTE, 3070, VIC. BC548 .20 2N3055 .85 BC549 .20 FT3055 .80 10 TIMERS s400 BD139 .60 TIP31B .75 SUPER SPECIAL 555 FOR BD140 .60 TIP32B .75 BF180 .60 TTL X LP -3-31 $2.95 7400 .25 7432 .36 X LP -3-32 $2.70 7401 .25 7437 .55 XLR-LNE-11c $2.75 OPTOELECTRONICS FND 357 .375" c.c. 1.30 7402 .25 7438 .55 XLR-LNE-32 $3.90 FND 500 .5" c.c. 1.40 7403 .25 7440 .25 RED LED .22 7404 .31 7441 1.30 GREEN LED .35 7405 .31 7442 .75 TOGGLE SWITCHES YELLOW LED .40 7406 .77 7443 1.75 NKK Ultraminiature 7407 .77 7444 1.75 U2012 SPST .75 7408 .28 7445 1.39 U2013 SPOT (Centre off) 1.00 7409 .28 7447 1.15 U2022 DPDT .90 ELECTROLYTICS 7410 .25 7451 .25 U2023 DPDT (Centre off) 1.20 4.7uF 25V PCB .07 7411 .31 7454 .25 10uF 25V PCB .08 7412 .25 7470 .59 10uF 50V PCB .09 7413 .47 7474 .55 CMOS 22uF 16V PCB .07 7414 .86 7475 .66 4001 .25 4021 1.40 22uF 35V PCB .09 2416 .78 7491 1.01 4002 .25 4023 .25 33uF 16V PCB .08 7417 .78 7492 .61 4006 1.40 4024 .86 33u F 50V PCB .10 7420 .25 7493 .61 4007 .25 4027 .83 47uF 16V PCB .09 7421 .25 74107 .50 4008 1.32 4028 1.25 47u F 35V PCB .11 7423 .44 74121 .51 4011 .25 4040 1.30 100u F 10V PCB .10 7425 .44 74123 1.25 4012 .25 4049 .60 100uF 16V PCB .11 7426 .38 74141 1.14 4013 .55 4066 .85 220u F 25V PCB .14 7427 .44 74175 1.60 4014 1.40 4069 .30 470uF 16V PCB .16 7430 .25 74367 1.25 4015 1.20 4510 1.46 1000u F 25V PCB .36 4016 .55 4511 1.46 2500u F 50V Axial 1.85 VOLTAGE REGS. 4017 1.40 7805 5v 1A. 1.30 4018 1.40 7806 6v 1A. 1.30 TANTALUMS 7808 8v 1A. 1.30 1uF 35V .18 2.2uF 35V .20 LINEARS 4.7u F25V .22 10uF 16V .20 7812 12v 1A. 1.30 uA311 .80 uA339 .85 15uF 16V .27 22uF 16V .30 7815 15v 1A. 1.30 uA3401 .85 uÁ555 .45 7818 18v 1A. 1.30 uA556 1.10 uA741 .35 7824 24v 1A. 1.30 9368 1.75 LM380 1.25 POTENTIOMETERS 7912 -12v 1A. 2.00 RL4136 3.60 723 14 PIN DIL .45 .25 watt rotary carbon single gang, Log or Lin. 1K, 5K, 10K, 25K, 50K, 100K, 250K, 500K, CANNON CONNECTORS DIODES 1M. .45 X LP -3-11 $2.05 0A91 .15 0A95 .16 5K Lin Slide Pot .75 X LP -3-12c $2.95 1N4002 1A 200V .07 1N4004 1A 400V CERAMICS Weller cordless soldering iron kit model 1N5625 5A 400V .45 10p F to 680 pF .05 WC1000KW Includes batteries, solder 4 interchangeable tips, battery charger plus 1N 4148 .05 820pF to .0015uF .06 Instructions for only $28.50. All goods new .30 AMP 400V Bridge 4.75 E12 Values. and guaranteed. Price list enclosed with each order. Postage and packing charge 50c per order. PRICES CURRENT TILL 31/4/78 INCLUDE 20c POSTAGE FOR FREE CATALOGUE 1RYIN6 P.O. Box 135, NORTHCOTE, Vic. 3070. 499 HIGH STREET, NORTHCOTE, Vic. 3070 Phone (031) 489-8131. Intersil 31/2 DIGIT, PANEL METER E -Z- MACRO -HOOK

..tra.a. LCD a ..,, . or ,,.. ,. aii au,

LED: 14«- - KITS .,.

BUILD A WORKING DPM IN 1/2 HOUR WITH THESE COMPLETE EVALUATION KITS Test these new parts, for yourself with Intersil's low cost proto- typing kits, complete with A/D converter,and LCD display (for the 7106) or LED display (for the 7107). Kits provide all materials, including PC board, for a functioning panel meter. ICL7106EV (LCD) $29.95 ICL7107EV (LED) $24.96 HYBRID PART NO. XH

POWER AMPLIFIERS e Multi -purpose linear amplifiers for comercial and The Heavy -Duty Test Hook. Ideal for connections to large GQ . industrial applications. leads, terminals and lugs. Conductor and Hook are equivalent Less than 0.5% harmonic distortion at full power. in current carrying capacity to 14 AWG wire (.064" Dia. - f, dB responce from 20 to 100,000 Hz. 1.65mm Dia.). Spring -loaded and heavily insulated to a single Single or split (dual) power supply. contact point to assure true readings. ' Rugged, compact and lightweight packages. Construction: One-Piece Nickel Silver and Hook. current limiting for SI.1030G, SI.1050G Conductor Built-in Made for test connections over diameters up .125" (3.175 and efficient heat radiating construction. to mm). Durable Heat and Chemical Resistant Nylon Body and SANKEN Series SI -1000G amplifiers TYPICAL CONNECTIONS Plunger. Stainless Steel Compression Coil Spring provides e self-contained power hYbrid amp lifers designed for HI -Fi, steno, onus SI -1050G WITH SPLIT SUPPLY approximately 40 ounces (1244 Grams) contact pressure. leal Instruments. public address sye Colors: Red, Black. Specify tens and other audio applications. up M. color when ordering. The amplifiers have quasicomple- aru `t auru For Test Leads, see page 20. mentary class B output. The circuit r a sn ' '. m employs flip chip transistors with ea. w is ' For Coaxial Test Cables, see pages 30, 32, 34 and 37. high reliability end passatedw chip Field Serviceable. To connect replace leads, pull power transistors with excellent sec- *ant or straight out ondary breakdown strength. Built-InInm, on plunger until it slips free of body. Strip lead wire '4" Is for current limiting provided Si. se ruse (19mm), feed wire 1030G. 51.10506 and all devices ,_ -an through plunger and wrap around terminal can be operated fro mam single or n as shown in Fig. 1. Solder. Cut off excess wire at solder point. supply. ., 2Is n SI.10100 (10W output) S 6.90 1 3.25" SI.1020G 120W output) S13.95 -'.00n ac.. Socket for above .95 82.04 mm 1.625" 51.10300 (30W output) 519.00 .c l Wil li SI.10500 (SOW output) 527.80 7® 41.25mm Socket for above .95'ism 25y Date with Applkatlon Note,...S .50 K U.

' -r. -Illy 1/4 WATT 5% CARBON FILM - .: .3"DIA( ' RESISTOR 7.62mm <1..sON KIT .05" COMPLETE WITH STORAGE BIN 292,-a Each KIT contains 20 each of 42 . v) U1.27mm - different -values of %W Carbon Film 1 . 25"O.D. Resistors from 68 ohm to 4.7 megohm 9.53mm 22 " .xa 6.35mm .25" ' Order P/N RS -14-25 $24.90 6.35mm EXTENDED HOOK DETAIL GENERAL ELECTRONIC SERVICES P.O. Box 2208ET, Culver City, CA 90230 USA 99 Alexander Street, Crows Nest Phone (213) 641-4064 Telephone 439-2488. Melbourne Minimum order $10.00 Adelaide All prices quoted in US Dollars. Newcastle Please add postage to cover method of shipping desired. Brisbane Perth To expedite shipments, please include international money Canberra order or bankers' check payable against any USA bank in US $.

ELECTRONICS TODAY INTERNATIONAL - MARCH 1978 83 ,,41r,; DICK S y ITH FOR YAESU rl?

TheamateurCompare Dick's Yaesu prices with all the others - remember that these prices already include the recent Japanese price radió equipment rises. If you see a lower price, ask just one question: Where's the stock? YA E SU Dick has $100,000 worth of Yaesu NOW!

1 '1 lit - /to - Cat D-212 . 0::= Lit-_'! :5!?1,; I Cat D-2854 Cat D-2850 The radio of tomorrow - Compare: and be surprised! Calling all mobiles ... SAVE AROUND $1000 today! The FT -901D The YC-500S 500MHz counter Or those who would like to be! by buying the FRG -7 is extraordinary value for money. It's got to be the ham's dream. Here's the new Yaesu FT -227R - That's right - you could spend We a Full HF band coverage in all can't find comparable 2 metre FM, with 800 channels. well over $1000 dollars on a modes (yes, even FM) with the instrument under $700.00.. . Compare with other 2 metre rigs receiver with similar performance High sensitivity, with power rugged 6146 finals this is the and be surprised - the 227R is to the FRG -7 - and you'd waste top -of -the -line rig for the ham choice of 240V OR 12V! way in front (see EA March '78). $1000. High sensitivity, high who wants the ultimate. Versatile? It's more than that! Comes with microphone and stability - the Wadley Loop circ- Built-in 240V supply, DC -DC Ideal for the 432MHz operator, mounting hardware, is ready to uitry gives you top performance. converter optional. A really ideal also for servicemen. go on simplex, repeater (& rev) 0.5 to 30MHz reception, 12V outstanding piece of gear! or new tone repeaters. Superb! or 240V powered. EVEN LESS DUE WITHOUT IN S/TAX! SHORTLY!$380 35 $350 SEE THE ALL-NEW 1978 ELECTRONIC ENTHUSIASTS CATALOGUE - FREE IN APRIL ELECTRONICS AUSTRALIA. YAESU-MUSEN PRICE LIST Remember! We are proud to announce that the SUPER SPECIAL! All these prices include the superb range Hy -gain amateur latest of Japanese cost increases - and we band antennas are now back ... have the stock in our stores NOW. Don't be fooled by adverts which promise the TH6DXX earth but can't deliver the goods! Top of the range - a 6 element tri-band beam for 20, 15 & 10. Gives a mighty D-2546 FL -2100B Linear Amp $540.00 8.7dB gain. 7.3m boom length. A-5BQN MULTIBAND D-2850 FRG -7 comm. receiver $350.00 Cat D-4308 ...... $320.00 HF D-2854 FT -901D HF transc. $1275.00 RECEIVE & TRANSMIT TH3 Mk 3 D-2856 DC -DC cony. for 901 $75.00 ANTENNA Compact 3 element tribander gives 8dB D-2860 FT -101 E HF transc. $895.00 gain from 3 elements. Weight is only Here's D-2862 YO -100 mon. 'scope $330.00 your chance to save! The A-5BQN 16.3kg, boom length 4.3 metres. was selling for $51.00. Look again! Now D-2866 FT-7 HF mobile trans. $515.00 Cat D-4306 ...... $249.00 you save $11.50 on this deluxe antenna. D-2870 FT-301 HF s/s trans. $995.00 It comes complete with instructions, nuts D-2872 Power supp. for 301 $170.00 TH3 JR & bolts, plus aluminium antenna wire -- D-2880 FT -301S HF transc. $710.00 Superb little (?) antenna- it's the baby of sure you need a lot of room for this sort of antenna but look at performance! D-2882 YO -301 mon. 'scope $355.00 the range but lacks nothing in perform- - the ONLY A FEW LEFT AT THIS PRICE! 'D-2884 FL -110 linear amp $210.00 ance. 8dB gain, 3 element. 3.7 metre D-2890 FT -227R 2m transc. $335.00 boom with 4.4 metre turning radius. ' D-2892 YC-500S dig. counter $380.00 Cat D-4303 .. $199.00 FT901 D & FT -7 Due In shortly! 18AVT/WB 1 50 ALL Yaesu amateur equipment is fully Vertical trap for 80 through 10 metres, ONLY covered by Dick's famous guarantee on 7.6 metres high. Rugged construction. parts and labour - and is backed by the Sure it costs $10 more than the 4BTV - largest service department of any similar but you get 80 metres on the 18AVT! organisation in Australia! Cat D-4301 ...... $125.00 NEAR COST!

value P&P charge SHOP HOURS Ortler 45 00 Mon F. 9AM 5 30PM bonlicarp t - 14g9Y 2.00 Sao 4AM 12 noon 49 9 3 00 (Br Ahane' Lour embed 4 00 DICK SMITH ELECTRONICS welcome here t 99o9more 5.50 SYDNEY SYDNEY. SYDNEY: SYDNEY. MELBOURNE, MELBOURNE: BRISBANE: ADELAIDE: 125 York St, 361 Hume Hwy. 162 Pacific Hwy, 30 Grose St, 399 Lonsd.de St, 656 Bridge Rd. 166 Logan Rd, 203 Wright St, Coy. Ph 29 1126 &urkstown. Pt, 709-6600. Gore Hell. Ph 439-5311 Parran,.tta. Ph 683-1133 City. Ph 679834 Richmond. Ph 42.1614. Buranda. Ph 3916233 City. Ph 212-1962 Open 'ell 8PM Thursday Open'tsl 8PM Thursday Ample parking at door. 1st floor - l ..-ndly store, New: right en town Easy access: huge stock. Opens 8.30AM Now Open. See us! MAIL ORDER DEPARTMENT: PO Box 747, Crows Nest, NSW 2065. Phone 439.5311. Post .8 Pack extra. WE HAVE DEALERS RIGHT ACROSS AUSTRALIA - THERE'S ONE NEAR YOU! Project 140

1 GHz FREQUENCY METER - TIMER Pt.l Circuit Details

Lab -quality instrument offers superb performance and features at low cost.

OF THE VARIOUS QUANTITIES encountered in electronics (such as SPECIFICATIONS ETI - 140 charge, voltage, current, frequency), perhaps the easiest to measure accur- Modes of operation Frequency, period and time ately is frequency. Various types of Range frequency -measuring equipment exist, Frequency 10Hz - 50MHz ranging up from the simple absorption High frequency 50MHz - 1GHz * wavemeter ham should have one) (every Period 0.1µs - 10 sec. to sophisticated multi -counter instru- Time 1µs - 100 sec. ments which use microprocessors to calculate the measured frequency. Resolution The earliest really accurate instru- Frequency 1Hz ments were of the heterodyne type High frequency 10Hz (such as the BC221), in which finely Period 0.1µs calibrated oscillator was tuned to zero - Time 1ps beat with the incoming signal. Many of Display 8 digit LED, leading edge blanking these devices are still in use. In the late fifties and early sixties came the first Sensitivity 'digital' counters appeared, based on Normal input 20mV Dekatron tubes, which are cunning de- High frequency input 20mV cade counter and display valves. Time inputs OV to +3V level shift Integrated circuits and LED have now Input impedance made possible compact, portable count- Normal input 1 Meg // 15pF ers that can be held in the palm of the High frequency input 75 ohms hand, and these can easily be built by Time input >10k the hobbyist. we haven't seen how- What Maximum input voltages ever, is where a design for use at UHF, Normal input 70V ac,+ 100V dc CB and mobile radio, are appearing, High frequency input 200 mV ac ,T- 50V dc or which offered versatile measurement Timing inputs +100V dc of time or period. With these thoughts in mind, we set Crystal frequency out to do a design study, and came up nominal 4000 kHz with a lab -quality instrument which actual 3999.995 k H z should be very reasonably priced. The Stability and accuracy design is based mainly on TTL with Frequency Depends on crystal used and initial some CMOS and ECL. We rejected LSI adjustment. Oven used keeps temp- MOS and CMOS devices for various erature within 2°C. reasons: Although this increases board Period and time approx -0.000125% size and power consumption, the gain in simplicity of layout and trouble- * The upper limit of the prescaler has not been checked due to the lack shooting, as well as leading zero sup- of a signal source but both the preamplifier (OM335) and the divider pression, is well worth -while. ICs are specified up to 1 GHz.

ELECTRONICS TODAY INTERNATIONAL - MARCH 1978 85 Project 140

Design Feature When considering this instrument initially we looked at ways to reduce both cost and component count of the unit. Our initial design of the counter section used TTL for the first two stages and CMOS Y. for the rest. It then called for four 8 bit shift registers to take the information from the counters, latch it, and provide the multiplexing for the display. Multiplexing reduces the power consumption of the displays for the same light output and the total network would have saved 10-11 packages. However the PCB layout beat us unless a plated through board is used which would have cancelled any cost saving. The increased W' difficulty of fault-finding, even with fewer components, also weighed against 0 this approach. The counter in the LSD position has to operate at over 50 MHz. The only way to obtain this performance was to make our own divide by 10 using 74S74 dual D type flip flops as the 74LS90 is only specified to 32 MHz (although one sample we had worked at 60 MHz) and 74S90 is no faster. the pulses or level changds, into the respect- Adjustment of the crystal trimmer The network of 74S74'g should ive sockets. A voltage change from OV to should not be done until it is warm give 60-70 MHz minimum clock rate. 3 V (or +3V to 0 V) is all that is necessary (allow 10 minutes) and the oven should Preamplifiers which can work from although up to + 100V can be used. be fixed into the chassis to prevent almost dc 50 + MHz involving a to For accurate timing the pulse should movement of the leads which can affect Schmitttriggeralways prove troublesome have a rise time of less than 1 µs. For the frequency slightly. If CVI does not and was no exception. We this one measuring single pulses, both inputs have enough range the parallel capacitor dc coupled it throughout originally can be paralleled and starting and should be varied. using matched FETs and a differential finishing on opposite edges. If it is a The period mode should be checked pair to give the correct level for the repetitive pulse chain the unit will time for operation. With the time mode the 9585 IC. This proved to have too much the first pulse after the release of the display can be reset by the push button gain to be stable and the design shown reset button. and timing can be started by shorting here was final result. Originally we the out the start socket and stopped with used three diodes to the output limit Calibration and Testing the stop socket. Starting and stopping voltage to +2v in the EC L-TTL translator To calibrate the unit a known frequency can also be performed by switching the but replacing it with a resistor -diode not is needed so that CVI can be adjusted to polarity switches from negative to posit- only made it cheaper but increased the give the correct reading. Alternatively a ive edge triggering. It should not be frequency response by 50% and improved radio receiver can be used tuned to the possible to restart the counter before stability. PMG 12 MHz time transmission, VNG, the display has been reset. and the 4 MHz crystal beat against it Operation (take a wire from pin 11 of IC30, wrap The frequency and period modes are it around the radio aerial and adjust for +5V +8V commonly known and do not require zero beat. This sets the crystal to exactly much explanation. The only extra 4 MHz. However this is not the exact control provided over the normal sen- frequency needed (life wasn't meant...). sitivity control, is the dc shift. When Now feed the 4 MHz into the input and measuring the frequency or period of record the result. It should be about a pulse waveform where the pulse is 3,999,995 Hz which is about 0.000125% narrow in relation to the repetation low. Now measure the frequency of rate, triggering problems can arise. This another crystal (or extreme/y stable) is due to noise pulses being counted oscillator, record the reading and then as the average voltage is almost zero. adjust CVI to give a reading 0.000125% However by using the dc shift the sig- higher (or whatever error your unit nal can be lifted above (or below) zero requires). As this low reading is due to and the problem eliminated. For max- the time required for the strobe -reset imum sensitivity on normal ac signals pulses it is independent of the crystal the dc shift must be adjusted back to frequency and adjusting CVI will not zero. affect the reading when the counter is ov With -0 the time mode intervals from used to measure its own internal Fig. 1. The circuit diagram of the oven circuit 1 µs to 100 sec can be measured using frequency.

86 ELECTRONICS TODAY INTERNATIONAL - MARCH 1978 Tima T IT WC cac - I'1 RIqt1 Period _c m c sec 1R1O 7,111

50-1000MHz 0 50 MHz sTART k1Fl

Frequency -M Hz- k Hz Hz Hi Freq A Hz k Hz -Hz z 10- - dc SHIFT di140 SENS 1TOP z 00/114 I 1l1( )( '1-.\'('Y Ml:"11-R -"11N11.k

The following pins are not shown on the To +5V To O V circuit diagrams but are connected as IC20 3,16 8 shown below. Pins in the third * column IC21 3,16 8 are used as interconnections or are IC21 3,16 8 1--- unused inputs terminated to some IC22 3,16 8 output. IC23 3,16 8 To +5V To O V IC24 3,16 8 ICI 4,10,14 7 IC25 3,16 5,8 t1- IC2 4,10,14 7 IC26 14 7 8,9 IC3 5 4,6,7,10 13 IC27 5 2,3,6,7,10 IC4 5 4,6,7,10 13 IC28 14 7 -` i ; IC5 5 4,6,7,10 13 IC29 14 7 \IW.,.. IC6 5 4,6,7,10 13 IC30 14 7 IC7 5 4,6;7,10 13 IC31 2,4,6,7,10 11 IC8 5 4,6,7,10 13 IC32 16 1,7,8,9,15 IC9 5 4,6,7,10 13 IC33 16 1,8,9 1,2,3 IC10 5 12 IC34 14 7 IIIIIIII IC11 5 12 IC35 16 1,7,8,9 1N IC12 5 12 IC36 14 7 í IC13 5 12 IC37 2,3,11,16 8 alI IC14 5 12 IC38 14 7 1,2,5,6 Fig. 2. Waveform diagrams showing the IC15 5 12 IC39 14 7 relationships of the strobe -reset pulses. They IC16 5 12 IC40 5,14 6,7,8 are, fromI' the top down: IC17 5 12 The output of 1C37/1, pin 13 IC41 14 7 The 'strobe' pulse, i.e. the collector of Q2 IC18 3,5,16 8 IC42 2,3,5,6 The input to IC37/2, pin 10 IC19 3,16 8 The reset pulse on pin 5 of 1C37/2 The vertical scale is 2 V/division while the horizontal is 200 ns /division. It can be seen that between the strobe pulse and the reset pulse there Is a delay of about 50 ns.

OUT IN IC49 O +5V 7805 FOR PREAMP C39 + +I. C40I'C41 c IC42 10N 33,133n T 33 IN IC48 OUT +18V 7818 . C271 COM D12 cull

i IC25 °P11 220z T + 1 C21 013 2201. 014 Ti IN OUT IC46 0 +5V 240V/15V+15V 7805 @ 1 AMP + COM 1C31 IC32 IC33 1.C344 1.C35T33N C36 C37 C22 O C23 C28 T331. T334 ¡33n 33n 33n ACTIVE O--0 2500, 25°DN 330 015 33013> 240V INPUT 0 0V 016 NEUTRAL 0-.0 _ iC29 1 C24 ..--,--. 33n 2500N GOM IIN our 0 -5V EARTH O-- 7915IC47 D77 I Fig. 3. The circuit diagram of the power supply I fi

ELECTRONICS TODAY INTERNATIONAL - MARCH 1978 87 T 1 GHz FREQUENCY METER - TIMER

HOW IT WO R KS - ETI 140

The circuit is complex but can be sparated the two inputs Q9 and Q13 are used to stop dividing (this is used in the time totally wrong result. Because of this we use into sections to make the explanation disable one of the inputs. With both mode). This 1 MHz output is then divided the RS slip flop IC38 which is set by the clearer: transistors off the prescaler output is to 10 kHz by IC32 (dual decade counter) strobe pulse, stopping any further pulses, A. input preamplifier. disabled (it needs a pulldown resistor), and then to 100 Hz or 62.5 Hz by IC33. and reset by the 'C' output of IC35/2. This B. Prescaler. leaving the normal input active. If the This IC is a dual divide by 16 counter with IC (IC35/2) is reset by the strobe pulse C. Counter section. transistors are on the prescaler is oper- the AND gate IC34/1 resetting the first half and the 'C' output does not occur for D. Time base. ational but the dc shift on pin 16 of IC42 (IC33/1) upon reaching decimal 10 and 400 ms giving a maximum reading rate of E. Frequency -period control logic. forces the output (pin 7) high, effectively IC34/2 and IC34/3 resetting the second 2.5 per second. The reset pulse is not in- F. Time measurement control logic. disabling the input. half to zero at ten if the control input to volved in this process and occurs every G. Power supply. pin 13 of 1C34 is high. If it is low the reset 10 clock pulses of the input. Counter Section pulse is disabled and the counter will Preamp The counter section consists of eight divide by its normal 16. This change in Time Measurement Transistors Q6, Q7 and Q8 form the high decade counters, latches, decoders and the division ratio is necessary as the prescaler Separate inputs are used for time to low impedance unity gain buffer LED displays. Due to the symmetry of the divides by 16 and not 10. A final division measurement with both start and stop required to allow the one megohm input network the centre four stages aren't shown by 100 is done by IC37 to give the final inputs available. These inputs are buffered impedance. Diodes D5 and D6 prevent on the circuit diagram. timebase periods of 1 s and 1.6 s. by IC39 with both true and complementary excessive input voltages damaging the unit. Seven of the counter stages are the outputs available. Amplification is provided by IC42 familiar 7490/7475/7447 combination Frequency -Period control logic. Timing is done by coupling the 1MHz which is an ECL triple differential line (except that they are the LS versions) but In the frequency mode the output of the output to the count input (via IC28/2, amplifier. Each stage has a gain of about the decade counter of the LSD (least preamp is coupled to the count input of IC28/3 as per period mode), holding the seven giving a total voltage gain in IC42/1 significant digit), which has to work at the display section via IC28/1 and IC28/3. latches open so the counter information is and IC42/2 of around 50. The inputs of over 50 MHz is made out of four D type These need to be 74510 (not LS) to handle always displayed and controlling the divide IC42/1 are biased to the internal reference flip-flops using a NOR gate to get the the frequencies involved. The 1 sec (or by 4 (IC31) to stop and start the counting. voltage (pin 11) by R91 and R92 with the divide by ten function. Both the D type 1.6 sec) time base is coupled to the This control is performed by the D type input signal being ac coupled via C10,11. flip-flops and the NOR gate have to be 'S' monostable IC37/1 via IC36/1 and IC36/3 flip flops IC40/1 and IC40/2, after being The voltage on pin 16 can be dc shifted to series TTL to give 50 MHz + operation and is therefore triggered every one second gated by IC41/3 and IC41/4. If the Q allow better triggering on pulse type inputs. (our prototype went over 100 MHz!). generating a pulse 800ns wide. This is used output of IC40/1 is a '1' and the Q output The third section of IC42 is used as a All the counters can be reset by a '1' for the strobe pulse (open and close the of IC40/2 is a '1', IC31 will be enabled. Schmitt trigger to ensure that the output on the reset line and counting is advanced latches every one second). This output also When the reset button is pressed IC40/1 is is square and jitter free. As the outputs of on the positive transition of the count disables counting during this period to set to a '0' on Q, and IC40/2 to a '1' on Q, ECL move only from about +3.3 V to input. With the latches, if the strobe line is eliminate any error due to the latch closing disabling IC31. This also puts a high on the +4 V (on a +5V supply), a translater is high ('1'), whatever data is presented to it while a pulse is still rippling through the 'A' input of the reset monostable IC37/2. needed to drive the TTL logic which by the counter will be transferred to the decade counters. When the button is released this causes a follows. decoders. When the strobe line goes to a The output of this mono has to be reset pulse to occur resetting the counters Transistors Q10 and Q12 are both '0' the data present at that time will be buffered by Q2 as the input of the latches (and display) to zero. constant current sources with Q12 stored and displayed with the information is equal to 32 LS TTL loads (about 15mA). The D input of IC40/1 is normally providing about 18 mA (0.6 V across from the counters no longer affecting the This transistor causes a propagation delay connected to a '1' and this is clocked into 33 ohms). As the base of QIO can be display. of 100 ns on the leading edge and 50 ns on the Q output on the positive transition of either of two levels (3.3 V or 4 V) it Due to the interconnection between the trailing edge. After a delay at about the input to pin 3. When this occurs count- supplies either 33 mA (1.1 V across the decoder IC's the leading zeros will be 80 ns (which is to compensate for the 50 ns ing will start. This also puts a '1' on the 33 ohms) or 9 mA (0.3 V across 33 ohms). blanked, leaving only the right hand digit propagation delay of Q2) the second D input of IC40/2 and if a positive trans- As the two current sources are in series the on with no input signal To reduce the monostable IC37/2 is triggered giving a ition occurs on pin 11 (clock) the Q will differential current must go somewhere if load on the 5V regulator the displays are 250 ns wide pulse. This ís the reset pulse. go to a '1' and the Q to '0', which will they are to remain constant current supplied from the unregulated supply. The process of frequency measurement is stop the counting. Triggering the stop supplies! With 33 mA from Q10, the therefore to reset the counters, clock the input before the start will have no effect difference (15 mA) flows through R103 Timebase counters at the input frequency, after 1 sec as the D input is a '0' and once toggled no and D9 to give about +2 V on the output. The timebase is a 4 MHz crystal with open and close the latches which displays further action will occur until reset by the When the current drops to 9 mA the IC30/1 and IC31/2 providing the necessary the number reached by the counters, then pushbutton. Either positive or negative clamp diodes in the 74S10 which follows amplifier to make an oscillator. The immediately reset the counters and start edge triggering can be selected allowing the preamp clip the voltage at about frequency is adjustable by CV1. For the process all over again. the width of a pulse to be measured by -0.7 V. If these limits were not used the critical applications an oven can be used, In the period mode the 1 MHz output feeding it to both inputs and selecting the transistors would saturate, reducing the and this is controlled by Q3 and Q4. These from IC31 is gated into the count input via appropriate edge. response to a few MHz. transistors compare the voltages on their IC28/2 and IC28/3. The output of the bases and control the drive to Q3, which, preamp, after being divided by ten in IC27 Power Supply Prescaler along with R86 and R87, is mounted on then controls the strobe -reset monostables Four voltages are required for the unit: +5 For frequencies above 50 MHz, a prescaler the crystal body to act as a heater. Also on via IC36/2 and IC36/3. The result Is that volt for most of the logic, +8 volts is used with an amplifier IC43 providing the crystal body is the thermistor TH1 we count the number of one µs pulses in unregulated for the displays (to save power about 26 dB gain frequencies up provides to to which the necessary feedback to. the time taken for 10 cycles of the input disapation in the 5 volt regulator) +18 volts about GHz 1 and 1C44 and IC45 each Q3 to stabilize the temperature at about frequency. This gives the period of one for the prescaler and -5 volt the dividing the for signal by four to give a total 70°C. The crystal is mounted in a poly- cycle to 0.1 µs accuracy. Problems with preamplifier. A separate +5 volt regulator division by 16. To compensate for this styrene box to provide the thermal flickering occur when updating a display is used for the preamplifier and prescaler odd division the timebase is changed from insulation required. more often than about 1/5 sec, especially to prevent any feed back via transients in 1 sec to 1.6 sec when the prescaler is used. The output of the oscillator is buffered 7 segment displays, as the eye cannot follow the 0 V line. As these dividers are ECL else by (what IC30/3 before being divided by four by the change. This can be shown that if the The regulators are standard 3 terminal at 1GHzl) a similar translater is used the JK flip flop IC31. If the JK inputs of display is alternating between 100 and 99 regulators with the z 8 volt supply (Q11). To prevent interference between IC31/1 are taken low the flip flop will the result could appear as 188 which is a simply fullwave rectified. The +26V for the 18 V regulator is voltage tripled.

*5V

RV2 1k R 89 220R Vref C20 R93 R 102 R114 338 10p 1k 4k7 b/ L C19 06 C OV loa, 22ÓN 010 011 d NORMAL 15. 14 6 7 b b `rl R88 9 1M C11 100n IC42/1 IC42!2 IC42/3 16 13 10 2 OUTPUT RV1 891 R92 :le -D5 06 R95 R103 LO 1k 1k 1k R98 R100 R 101 100R 09 R96 R97 220R 220R 2208 Vref 2208 2208 R99 L14 b 2208 C18 09 100n T T100n Vref OV

R94 07 1k 012

137 + C12 R90 330 8104 47R 08 338

V +5V R115 *18V 106 a PRESCALER R108 R112 C15 1008 C43 1008 SELECTION 220p 14 14 INPUT HIGH FREQUENCY IC43 11 1110 4 0-111 -9 --- OM 335 INPUT

8106 IC44 1C45 R 110 R105 1008 1008 8113 1DOR C44 R116 In0 1508 3k3 -D10 -D11 6 0 10 h 013 17 7 C16.1 11107 R109 R111 b 1508 1508 1508 4. ON Fig. The circuit diagram of the preamplifier 0 1 GHz FREQUEII[V METER - TIMER 10 IC28/1 11 14 75510 INPUT COUNT FROM O IC27 PREAMP 74159 _MD OUTPUT +5V 3 IC28/3 12 74510 13 12 R57 3+3 7 IC29/1 IC213/2 +5V FR EOUE NCY 74LS00 74510 4 PR ESC AL ER SELECTION ' SELECTION INPUT 6 R63 INPUT VIM 3k3 IC29/2 R64 74L500 D17 47013 TO 2 DECIMAL ON 3 POINT DISPLAY 5 IC34/1 IC34/2 1C34/3

XTAL 4MHi DV1 5V 4 13 12 10 F9 _ 1 6 º L R62 11 3k3 15 12 2P 1 R59 IC30/3 12 IC32/1 6 L10 IC32/2 IC33/1 IC33/2 IC35/1 6 100 IC35/2 14 741500 4518 4518 4520 4520 43+3 12 4518 4518 C31:2 ,4_11 13 15 74LS73 2 C2 +5V IC30/1 10n IC30/2 74LS00 741500 0,C 1n0 R65 R60 T 3k 3 3k3 OV IC29/3 TIME 74LS00 +5V 55V SELECTION O 13 INPUT 11

IC36/1 R67 169 +5V 4011 15k C4 10k a

R61 IC36/3 336 4011 15 14 R68 7 6 IC29/4 12 330R PERIOD 774LS00 11 9 IC37/1 10 IC37/2 RESET SELECTION O 13 74LS123 74LS123 3-0 INPUT 8 IC36/2 BUTTON 4011 3 C5 CR80 1 .5v 1n0T 1470R OV TO DECIMAL +5V POINT ON IC41/3 DISPLAY 1 4011 R77 33k D7 IC39/1 4011 SW2 5 IC40'1 START 4013 +5V INPUT R76 10k IC39/2 D2 4011 4 IC41/4 4011 R75 470+ OV C9 +5V 100P IC36/4 STRUTPUTOBEO 4011 02 I PN3643 379 IC39/3 R73 SW3 33k 4011 11 10k

STOP 0 I4013C40/2 INPUT !J w. 11./R78 12 10k IC39/4 D4 4011 C7 R72 10 100P 10k

OV OV IC41/1 OV

R74 10k FBI +5V R70 RESET 10k BUTTON

IC41/2 4011 OV Fig. 5. The circuit diagram of the control logic Fig. 6. The circuit diagram of the display logic +8V +8V

L I LSD DISPLAY 1 MSD DISPLAY 2 DISPLAY 7 DL707 DISPLAY 3 - DISPLAY 6 DISPLAY 8 DL707 DL707 01.707 a b c d e t a g b c d f a b c d e f g a b c d e l g

R56 sv-1111111 4709 13 10 12 11 9 15 /4 13 12 11 10 9 14 IN 15 13 12 11 10 9 15 14 13 12 11 9 10 15 14 C18 IC20 C19 - IC23 IC24 C25 7 1547 741S47 4 741.547 741S47 7 1 6 7 1 2 6 7 1 2 6 7 1 2 6

STROBE 4 9 16 15 10 9 16 15 10 INPUT 9 16 15 10 9 16 15 10 C10 Cl 4 4 IC12- IC15 C16 IC17 74LS75 74LS75 I 7 13 13 LS75 74LS75 7 2 13 3 13 7 2 6 7 2 3 6 7 2 3 6

12 9 8 11 12 1 8 111- 12 1 9 8 11 IC3 IC4-IC7 4 IC8 IC9 U. 5 12 74LS90 14 1fi7 LS90 11 74LS90 11 2 3 2 COUNT IC1 3 IC2 11 IC2/2 3 IC1/2 3 2 3 INPUT 74S7/1/ 7457/14 74S74 H 74S74 6 8 r 1

13 13

IC26/1

74502 IC26/2 12 13 11 74502 IC26/3 5 4 RESE O INPUTT 74S02

Time sec. m sec. -µ Sec. PERIOD Period-sec.- - m sec. N sec. Qo o FREQ. O TIME o o 50-1000 MHz 0-50 MHz START f RESET Frequency -M Hz- k Hz -Hz Hi. M Hz k Hz x 0 Freq. -Hz 10- 0 o o 140 SENS. dc SHIFT - eli STOP POWER FREQUENCY METER TIMER

Fig. 7. The front panel artwork. Full size 320mm x 55mm A VATEUR CO`:-' V J\JCA1iO\S ea FACT Symposium V-FETS provide a maximum gain of Halving Voice Bandwidth Future Amateur Communications 10 dB at 175 MHz and source to drain The December 1977 issue of QST Techniques is the title of a symposium breakdown voltage is more than 65 volts. published a rather exciting article on to be held in Sydney over the Typical on -resistance for the 100 W BF a new system of modulation which weekend of 20-21 May, this year. 100-35 is quoted as less than one ohm halves the bandwidth of voice The Symposium is being organised for a drain current of 10 amps. transmissions. by the NSW VHF & TV Group but The 'new wave' of solid state power Titled 'A New Era in Voice the topics to be covered by the amps will undoubtedly use V-FETS Communications' and written by symposium will not be limited to the which are more rugged than comparable Richard Harris (Assistant Professor, world above 50 MHz. bipolar devices as well as simplifying Electrical Engineering, University of A variety of papers will be presented circuit design. The new FETS do not Stockton, California) and Judy covering the following topics: SSB experience thermal runaway or break- Gorski (Editorial Supervisor, QST), on 1296 MHz, Modern ATV down and are more tolerant of load the article explains the principle of techniques, Solid State Power mismatch than bipolar devices. They 'Narrow Band Voice Modulation' and Amplifiers, Advances in Repeater rival bipolars in linearity as well, having details how amateur radio was involved Techniques, Sunspot Cycle 21, using similar third -order distortion figures and in both the development and the first Anomolous Propagation for HF & better higher-order figures by a factor of practical tests of the NBVM system. VHF DX, Microprocessors and 5 - 10 dB owing to the FET's Basically, the system works by Amateur Applications, Phase III Oscar law -type' transfer characteristics. taking advantage of the characteristics and Beyond, Advances in Transceiver Smack, drool and all that, but what of speech. Consonants carry the bulk Techniques etc. about the price? of speech identity and vowels and There may be some last minute CTC indicate that preliminary prices consonants are produced serially - one changes or additions to these topics fc: 1-24 are as follows: for the BF25- after the other, in time. Electronic but the range of subjects covered will 35, $37.50 (US); for the BF50-35, circuitry emphasizes and 'folds' the be maintained. $48.50 (US) and for the big one, the consonants into blank spaces not In addition to the presentation of 100-35, $76.50 (US). occupied by vowels as you speak. The papers a number of 'workshops' are vowels and consonants do not New being organised where you can get Stripline Substrate interfere on transmission as they do your eyeballs onto 'state of the art' The 3M Company has recently not occur at the same time. equipment and question the people announced a new substrate material for It is the folding action that who built it in close detail. microstrip printed circuit applications. accomplishes the saving in spectrum Papers and workshops will be It is called Epsilam-10 and consists of space. presented by amateurs who are a ceramic -filled Teflon material. It has acknowledged leaders ín their field the electrical properties of aluminium First practical tests were carried and many well-known amateur oxide (used with microstripline circuitry out between Tom Lott,VE2AGF/W6 personalities will be confronting the in UHR IC's) but it can be cut with a in San Mateo California and Clarence audience. razor blade or shears and can be etched (Smithy)Smith, KH6 BFF in Honolulu, The FACT Symposium has been like any other printed circuit material. Hawaii, in May last year. modelled on the very successful FAMPARC Seminar held in Melbourne late November last year. This Symposium promises to be the Amateur Radio event of 1978 -- don't miss it. You can ensure your place by sending a $10 deposit right now to the FACT Symposium Organiser, c/o WIA, 14 Atchison Street, Crows Nest 2065. Cheques or money orders should be made out to the 'FACT Symposium Account'.

High Power VHF V-FETS The communications Transistor Corporation has recently released a range of three V-FET devices for solid state VHF power amplifier applications char- acterised for operation at either 80 or 175 MHz. Designated the BF25-35, BF50-35 and BF100-35, the devices can deliver 25, 50 and 100 W respectively of continuous-wave power. The three

92 ELECTRONICS TODAY INTERNATIONAL - MARCH 1978 ' SWL COVV ,.VCNTIO\ S Compiled by Peter Bunn, on behalf of the Australian Radio DX Club (ARDXC).

Holland Radio Nederland's schedule, effective until May, shows the following broadcasts aired at convenient times for P.O. Hox NO :t97 KUWAIT reception in Australia: 0730-0820 GMT on 9770 kHz, 0730-0920 GMT on 9715 kHz, both these programmes beamed via the Bonaire relay station. 2030-2120 GMT 21640 and 17810 kHz (via Bonaire), 15220 kHz (via Lopik), and RADIO :r I on 11730 and 11740 kHz (via the (fillf . Madagascar relay station). KUWAIT Florida transmissions of I.NYFR. The religious broadcaster, Your Family Radio (WYFR), has provided details of transmissions via their new transmitters at Okeechobee in Florida. The station advises that reception reports of these Florida programmes are needed, and will be verified by a distinctive QSL card from the one issued for reports of their older transmitter site at Scituate QSL in Massachusetts. Florida broadcasts in English until the end of April will be: On 17865 kHz: 1605-1700 GMT, 1800- 2100 GMT. On 17845 kHz: 1700-1900 Voice of Zimbabwe. GMT, and on Sundays only 1230-1551 This programme, broadcast via the More DX notes on page 101.. . GMT. On 15440 kHz: 1700-1900 GMT. facilities of Radio Mozambique at On 11815 kHz: 2100-2300 GMT. Maputo, is currently audible in Australia on 4855 kHz at 1800 GMT. An English station identification for Radio

Swaziland. Mozambique is given at sign on, The Australian Radio DX Club is a non- Trans'World Radio at Manzini advises followed by the Voice of Zimbabwe profit body, with headquarters in Mel- of its current broadcasts on the 16 programme in English. The Portuguese bourne. For further information on short- language programming of Radio wave radio, and on the activities of the metre band. These services may be ARDXC, please write to the General heard until the end of April on the Mozambique continues at 1816 GMT Secretary, ARDXC, P.O. Box 67, Highett, following schedule: On 17775 kHz: with musical selections. 3190, Victoria, enclosing a 20c stamp. 1445-1500 in Lingala, 1500-1545 in French, 1915-1930 Lingala, and 1930-2015 in French. All programmes TRANS WORLD RADIO may be heard daily. Trans World Radio Manzini has plans to build two new 100 P, 0. BOX CC. AGANA, GUAM 96910 kilowatt transmitters to expand its coverage area to include South Asia and North and West Africa. At present, YOUR STATION FOR INSPIRATION programming is beamed primarily for reception in Southern Africa.

African signals. The Voice of Kenya has recently put a 146LCW new transmitter into operation. The Swahili language service is now carried "For God so loved the world, that he gave his on 4933 kHz, and offers good reception only begotten Son, that whosoever believeth 1500 in Australia from fade-in at about in him should not perish, but have everlasting GMT, through until sign off at 2013 GMT. Swahili news was carried at 2000 life." GMT. John 3:16 (Kings James Version of the Bible)

ELECTRONICS TODAY INTERNATIONAL - MARCH 1978 93 HITS

1 ETII 101R IECTS

ETI 446 Audio Limiter J E TEST EQUIPMENT ETI 447 Phaser E,J We get many enquiries from readers ETI 101 Logic Power Supply E ETi 449 Balanced Mic Preamp J ETI 480 50 W. 100 W Power . . . wanting ETI 102 Audio Signal Generator . . E,DS Amp A to know where they can get ETI 103 Logic Probe E ETI 480P Power Supply DAT kits for the projects we publish. The ETI 107 Widerange Voltmeter E ETI 482A Preamp Module A ETI 108 Decade Resistance Box ES ETI 482B Tone Controller A list below indicates the suppliers we ETI 109 Digital Frequency Meter . . . E ETI 485 Graphic Equalizer JS ETI 111 IC Power Supply ES ETI 480 50W, Power . A,D,B know about and the kits they do. ETI 112 Audio Attenuator ES 100W Amp . ETI 113 7 -Input Thermocouple Meter P E Any companies who want to be ETI 116 Impedance Meter ÉS included in this list should phone LES ETI 117 Digital Voltmeter E,AS ETI 118 Simple Frequency Counter E,AS MISCELLANEOUS BELL on 33-4282. ETI 119 5V Switching Regulator supply ETS ETI 602 Emergency Flasher E Key to companies: ETI 120 Logic Probe L,ES ETI 503 Burglar Alarm ET ETI 121 Logic Pulser L,ES ETI 505 Strobe L E,D ETI 122 Logic Tester ES ETI 506 Infra -Red Alarm E A Applied Technology Pty. Ltd. 109 - ETI 123 CMOS Tester ES ETI 124 Tone Burst Generator ES ETI 509 50 -Day Timer E 111 Hunter St, Hornsby. 2077. ETI 128 Audio ~voltmeter L,ES ETI 512 Photographic. Timer E NSW. ETI 129 RF Signal Generator L,ES ETI 513 Tape Slide/Synchroniser E ETI 131 General Purpose power ETI 514 Flash Unit - C Amateur Communications Sound Operated E supply E N ETI 515 Flash Unit - Advancements, PO Box 57, Rozelle, ETI 132 Power Supply NS Light operated E NSW. ETI 518 Light Beam Alarm ET D Dick Smith Pty. Crows SIMPLE PROJECTS ETI 525 Drill Speed Controller E Ltd. of ETI 206 Metronome ET ETI 526 Printimer E Nest, NSW. (see Ads. for address). ETI 218 Monophonic Organ ET ETI 527 Touch Control Light ETI 219 Siren ET Dimmer E E E.D. & E. Sales, Victoria. ETI 220 Siren ET ETI 528 Home Burglar Alarm P.ET .E J Jaycar Pty. Ltd. 405 Sussex St., ETI 222 Transistor Tester ETS ETI 529 Electronic Poker Machine ETI 232 Courtesy Light Extender E ETI 533 Digital Display L E,AS Sydney 2000. ETI 234 Simple Intercom ET ETI 534 Calculator Stopwatch A D ETI 236 Practice Oscillator E ETI 539 Touch Switch E L 1 Code Delsound Pty. Wickham Terrace. ETI 239 Breakdown Beacon E ETI 540 Universal Timer ES Queensland. ETI 541 Train Controller ET ETI 543 Double Dice ...... M Mode Electronics. PO Box 365, MOTORISTS' PROJECTS ETI 544 Heartrate Monitor A ETI 528 Home Burglar Alarm MS Mascot 2020. ETI 301 Vari-Wiper ET ETI 302 Tacho Dwell ET ETI 583 Gas Alarm M N ETI Nebula Electronics Pty. Ltd., 15 - 303 Brake -light Warning...... E ETI 309 Battery Charger P E 19 Boundary St., Rushcutters Bay ETI 312 CaIAElectronic Ignition ELECTRONIC MUSIC 2011. NSW. ETI 313 E DT ETI 601 4600 Synthesiser J O Appollo Video Games of Hornsby, 3600 Synthesiser .1 ETI 602 Mini Organ E,A,D NSW. AUDIO PROJECTS Pre-Pac P Electronics. 718 Parramatta ETI 401 Audio Mixer FET Four Input . E Rd., Croydon NSW 2132. ETI 403 Guitar Sound Unit E COMPUTER PROJECTS ETI 4Q6 One Transistor Receiver . . . . ET BKX Electronics Supply Service.179 ETI 7 Bass A E ETI 630 Hex Display A S ETI 408 Spring Reverb. Unit E ETI 631 VDU Keyboard Encoder A Victoria St., Kings Cross. NSW ETI 632 VDU 1 k x 8 Memory Card . A ETI 410 Super Stereo E ETI 2011. ETI 413 100 Watt Guitar 633 VDU Sync Generator A Amp P,L,E,J,DT T Townsville Electronics Centre. ETI 413 x 200 Watt Bridge Amp :SE 281E Charters Towers Rd, ETI 414 Master Mixer E,J RADIO PROJECTS ETI 414 Stage Mixer E ETI 701 TV Masthead Amplifier . . E,D Rising Sun Arcade, Hermit Park. 4812 ETI 416 25 Watt Amplifier E ETI 702 Radar Intruder Alarmp D ETI 417 Amp Overload Indicator E ETI 703 Antenna Matching Unit E ETI 419 . . ETI 704 Crosshatch/Dot Guitar Amp Pre -Amp. P.E.DT Generator ETI 420 Four -channel . . . L,E L,A,D,ES Amplifier ETI 706 Marker Generator ES ETI 420E SQ Decoder E ETI 707 Modern Solid State PROJECT ELECTRONICS ETI 422 International Stereo Amp S L,E D ETI 422B Booster Amp E Converters C E ETI 041 Continuity Tester ET1 422 50 Watt Power Module E ETI 708 Active Antenna E ETI 710 2 metre Booster. . . . C,E ETI 043 Heads or Tails DATS ETI 423 Add-on Decoder Amp . . E ETI 711B Single . A ETI 044 Two -Tone Doorbell DATS ETI 424 Spring Reverberation Unit . S L,E Relay Remote Control ETI 045 500 Second Timer DS ETI 425 Integrated Audio System E ETI 711C Double Relay Remote ETI 047 Morse Practice Set DS ETI 426 Rumble Filter E Control A ETI 048 Buzz Board DS ETi 427 Graphic Equaliser S L E,J ETI 711R Receiver A ETI 061 Simple Amplifier DATS ET1 430 Microphone Line Amp E ETI 711AR Remote Control Transmitter . A ETI 711DR Remote . . . A ETI 062 Simple Amplifier Tuner . . . DS ETI 433 Active Crossover E..1 Control Decoder ETI 063 Electronic Bongo's DS ETI 435 Crossover Amp E,J ETI 740 FM Tuner A ETI 064 Intercom ATS ETI 438 Audio Level Meter L,ES ETI 780 Novice Transmitter E ETI 065 Electronic Siren DS ETI 440 Simple 25 Watt Amp L,E ETI 066 Temperature Alarm ADTS ETI 441 Audio Noise Generator. . L ES ETI 067 Singing Moisture Meter DS ETI 443 Compressor -Expander . E.J. ELECTRONIC GAMES ETI 068 Led Dice ADS ETI 444 Five Watt Stereo ES ETI 072 2 -Octave Organ DS ETI 445 Preamp J E,D ETI 804 Selecta -Game O,A,DS

94 ELECTRONICS TODAY INTERNATIONAL - MARCH 1978 ..5cintific c ...... ,SPECIA v 8rahthrnh It4 ]I]TRADE A sliifilioc pocket scicolific calculator - r packed with features - with a REVOLUTIONARY 1200 H fl BAT HY.

things to do with their dollars than buy batteries for their THE LATEST TECHNOLOGY hungry calculators. Goodbye old-fashioned red and green display calculators. Your That's where the people at Unitrex come in. time has come and gone. No doubt many of you have watched those old faithful servants use up hundreds of dollars worth THE NEW SCIENTIFIC TECHNOLOGY of batteries - right before your eyes. Imagine what you could ;lave done with all that money! SAVES YOU MONEY ON A BETTER Use your calculator to work out how much money you save with a 1200 hour battery scientific, compared with the old- CALCULATOR fashioned type. It's easy I On an average the red and green The experts at Unitrex have developed a pocket size, liquid display calculators give 4 to 5 hours of continuous battery life crystal display scientific calculator (FEM type), thin, good at an average battery cost of 50c per set. That's really looking, light on batteries, that's always sure to perform when extravagant, isn't it? - you need it most. But until May 31st, we will even pay you $7.00 as a INTRODUCING THE trade-in to take your old calculator away. (It doesn't have to be a scientific). UNITREX LCD 8SC Just pack up your old calculator, with its instruction book Now you can trade up to the slimline Unitrex LCD 8SC (if possible) and send it to us, postage paid of course, togeth- Scientific, for much less than you would expect to pay for a er with your cheque for $39.95 ($37.95, for Unitrex Scientific calculator packed with all the scientific features you are sure and $2.00 for postage and handling) and we'll send you your to need. Unitrex LCD 8SC 1200 hour battery Scientific. If you do not have a calculator to trade in please send $46.95 ($44.95 for the LCD 8SC and $2.00 postage and r23956/77 handling.) Thank -you. If you can provide a valid sales tax certificate the prices are $35.00 and $42.82 (including $2.00 postage and handling) 1 respectively. The warranty on these units is days labour and 12 FEATURES b 7:1 90 months for all parts. 8 digit liquid LCD display. 6 5 digit mantissa with sign Please make cheques/postal notes etc. payable to 'Unitrex 2 digit exponent with sign. pp DEEM and send 35 key operation with Offer' orders to the address below. 2 mode select switches. IPQQWO Calculator range 10103 ®QQq to 10 103. MN WM MIN NM ISM WEI MN ME MIN Full scientific functions. wooN1a and send orders Degree radiant grad switch Make cheques etc. payable to 'Unitrex Offer' I tz..z j for trigonometric functions. C/-'Unitrex Offer', Electronics Today Int. - Statistical functions 15 Boundary Street, Long life battery operation. Over 1200 hours. RUSHCUTTERS BAY, N.S.W. 2011. 2 levels of parentheses and many, many extra features. Name How many of you have wondered where all the spare change went, when you wanted that new bicycle, stereo, CB radio or Address home computer; paying the battery bill on your old calculator would be a good bet. Some say the old red and greerr display calculators were just ' like having another mouth to feed in the family. In the course POST CODE of an academic year, a battery bill in excess of $200 would not I enclose cheque/postal order for . together with my trade-in be all that surprising. ' Just calculate the average cost of a unit. battery, say 50c, by the average life, say 5 continuous hours, 1 by how long you use it. Most schools and students have better OR

II I enclose cheque/postal order for as full price. NW ~I MN MIMI ME ~I NM = 110, ELECTRONICS TODAY INTERNATIONAL - MARCH 1978 95 Making negatives This method can be used to copy ETI artwork from October 1977 on only. The film used is Scotchal 8007 which is UV sensitive and can be used under normal subdued light. Cut a piece of film a little larger than the pc board and expose it to UV light through the page of the magazine. The non emulsion side should be in contact with the page. This surface can be detected by picking it up by one corner and it will curl towards this surface. Exposures of about 20 minutes are normally necessary. The film can now be developed by placing it emulsion side up on a table, pouring some Scotchal 8500 developer on the surface and rubbing it with a clean tissue.

P.O. Box 4430C Santa Clara, CA 95054 988-1640 Same day shipment. First line parts only. Factory For will call only: (408) tested. Guaranteed money back. Quality IC's and 2996 Scott Blvd. other components at factory prices. 00,,26 54 INTEGRATED CIRCUITS W'1]0 534 2wú9 1 t: 2045}9 79 1O151ó40 13995 W' » 144417.15 I 10 07001 21 004553 171 90-3 Ir 4445)S9Y]11 /443447.71 10 11 001540 }» 42001 0.2 12525 191ó ELECTRONICS 11 ?.15110 T 1I 19 01006 110 001533 150 r1511Y 35 1913430 4 S° D1007 21 0045115 1 10 9110a } 50 23 14574 I 0103e 21 3 m 0.16}5 64 91 LY4J3I9 47 1ó 99 114014000192 79 950 W00900 31.1.4 MOW. 1411315001 13 4 U 74117 593/4 51 116379 !CO 0 6srlm 1,911U13 5104.4.. 4m. 1100 ¡Kco110 YCW5n1 qm 0g5 01015709 Y SR 11 1415954 I4 1Y04 1m 0 21 21 334 3.M m5465d 40i 101 m 09.70N m Im4NI70N 077 i[ 1 39 74510711 4 .301 1 to DO l 21 74(14 t 10 111101.1 3 44 Ye. 94r,41d4 }I ,'0 1451191 .3.2 1 m 00401 % 74149 4 CISCO 4 4 1011474 53 nSY1M101675 50 74511311 23 40 0401 6 74030 20 CO 10= 01m1655 34 49 74513211 1} 947Ó1 49 0401 4 7410 295 úúv 4 i 13n i50 .17404105 63 .w 44,939.4,14 3 040 11N441 35 1Y4304 50 040 16 rar4 33 >J1} 3 4 0 444.e 510 95 74 1, 34 09 141515110 67 67 oN 7a1 Y45Ja i C404Nn,..d tlw00434 anS-191lDC915on, 67 1.1.741C11 N 74(m 1 IS 409014 451550 940 ] Mp6431 49 14510711 o4a u Iñ w 1y166e421:441ñi0ó11100r.34 º95 JrNM14en* 11y 91 62 004m0 741154 m 74I51149 1117472. m 4 WeSn 1Y 000,1. 111300115 úº 7437634 9i 0.0414m 1 774,1,76070 44 v1i lm 7451r4Y 95 .13034144. v ;r, 17191 im r : 1019 .er .m11.1.1e,4 56 1494 010} 741924 a 1i49N141 » t.,I.DIO,i44194W ió ICfi4Dom .4Y: Y4 74924 ú 3µº99914 194 119130430 1 } OW IS 14(}21 2 75 W5165 I 74m11 4µ13}0Y 11 IY1307 } m 0412 21 74C905 3 CO mml pYy, 0Y94 4 5á }»5 1 MOW 3 93 4 C0/4. LEO 111 YM1 .Nrp.,Y 7494 69 9 D404 1 51 HC906 m d 9 19. ó 741066 90 LY1359 2 47 D101 % 7a97 I4 Cr470 ? 95 I,rr9Y1.+.mr11P4 rg4 7..1 19211 1,0414m. 14 10.1674 ° 1044 44 540 4110114 040} ry 2K91] 190 I01Y.Ce1 N J115 49 900 .SN91704 C001710 NISI 9IºW1715 u 4}IY H 2Ay,6 1} LYt911 394 0409 102 44921 150 Wv15 f m WY RIY144.1. fJ5 "'..5 III 90 VVra 142w Y 0561ee9 CGN/0 21 4925 10 SO ,54Y. 4 1171 Ca]045 b lm 1 fr., C0 14lt112110 ,11111.1,1' 2 rrl 342254 59 CAy,1 11.2111 In 04015 1m 7414 10 50 745 1e 50 C1171114L. 1 4 Y Ñ 4 00, 150 m 1m 1111 14C923 10 50 05099e211 3 75 00 91 041 70010 111 1444 !4 3 n .w . 0n4r44 Y. 9i15á 94 A3Y9 I4 W34c04 r11'44C1 umn, ill r.4J11.» 741191 69 1143905 I ry U1110i902 515.1 294 fYO, 4ñ CA101040 4 n nW. v10, 566 1 m L1111611 61 DON 4 If II 4030744 1411 12 1000 m 1R a4 11 0 Ill WI 3 Ó 001 3m4ERSn4 7n.,1..0 25 14157% 9 W313, 5.04566 50 0401616r Ij w 1. e9 04049 16 fm 1}6vR4m1. in °15041 1103 4 1Y3004 4 21401 2 eów 6s ° 90 UV rna CA14101 IY /4162M II 65 414 14 4 920ñ110 m4a01914pr 9S40 4110 CC 149 19 1461p %I 11,5511 43 0190U5907SSOM 133 19 144 11 143 447690 . LY14y11M1 115 410 94 )41330 r9 Ow4m06147 1e 49 16 Y II1W 494 140CI4m14 395 W914I71 WG mOlm rs 9ra 4m 10301 141794 m 5.' 71 1491 1r I JS14Yw 149 141C11mr1 434 f2Jml» lY311104',.:Iii. Im e49 394 a 11 t m 0w 66 r14 e4 r.9 u G 1DO 7 m 741m0 1951Y31nn 2Ó1 0slbv IIS 0441 14 410 l5 4 m47,o444 ..1 ^» 911 21411Y Yw 4 n 1n3 DL47/RI WCC 500 I m 9rN 1 m 4:i9ñ 9 1140"'"70 r}4491w lm ú.1Ye.0439,`,°174"" 0740/40 [4CC 44 L1r4JIS , i1,1 ref nl9 320 '0.5 'IV Inm 7110 713 2¡07 1141Yw [C t4Á 195 142210 I V 140173.5 615 2 10 ITN I6º 1216Wi009110C45t00 (MO 114 144 1.95 D1750 717144 1 n14 5a611Yw 4mm 70045º 4 55 1.611124 I/ I4 4(p4072 21 er4 2n MO 94 INeoud4 743ev1 14m 4 04071 21 5 415 Yw 7 m e,[w,rlr 12 50 711p5tp500 MICA .11»4 t 4 1.111,- IS 1 40 1 4401 .e, d44 41:1,11t9 6 1,Iww,1w4 Y SOU 90 74164 4é 2 4114 1 n Oan }I baud In m 100163510 COG 9 !10 A 4 r II4 6 Yw 4 m , 41614 94 549 CY m Db76 I s 915]6 wd o4olrs n m YDIDnLDI wG 1 4 Iv91óJ w 140y07 1 a m r J4946eD4 1416/Il LL14112 150 754940 4 Db7e 4140,1.11,1,11017,74::: 9m I» 40L R1YN.eN 4 m 75494G 04142 }I 0 e104mY , 010Y 1116fm 013uerr a 7450Y a Ly3206 15 1 60 44 9 9b S m Op11W.VaY 1 75 115010 » l J239 415140.0v11415CU461 }120.1 14 1024 1 m Onw 4 1 13 95 1 21fm YIO r4Yr.r114 145039 » 15'3366 SS VOW/ C0446 50 195 124 caDIW747010Y0r1r1Y l4.7.41:11017111 34 94004 » m cD4490 5 50 4 22W.d9 3414r. Im 1 34a 5 1 l0 9070 4 e41 Ilm 74504 a +1 WW1. a eMtY 9bR31Y 1rm0J 1995 C04m7 4 m m 91,d04 4mm ] Jº 915.0 25 ,49N6a 115 21019 m e45 ?j1y o-lÁ¡I 101m 1 ]r -»Íf 144o.,.WY9N0mrer M1YY94o4anWr 60 14114 I 10 94 C0450 n 912.2 1m co919m0p 1m1.e4w54 » ,..3....,,N.Il A 140004510190 /WM. Camp a4, 4 N1907 u,. Ca. goo..lgoo..m 39 14514 a 15 410 9 111}2 120 C091902p ism rG s C04511 y04111 9 50 r45139 m 1Y14414 I10 lCl)Im 0m H4 C.141 12 95 3002100 II C Cr C..10 01w Ú C04515 2 52 25 4702245l4 1021.794 4444 420 42 11 0 s0Jr n li CO 243940 II 54Y1..0/44-Y.r 14041,49 W u r:Rétáilér" 111H5'0b1 m(91W74514 IS CO 93ri14 9.4.104 nu. 2 r w} 7 0W..1.16,1 no u904 cWtl úlr0i20 1Y3391.} I 10 C04000 It .45 a 63m N m 200m5 94+W 104. I^ 61069169 Y n.1:n 55 5.01, 235 mn

Sinclair 31/2 Digit Multimeter 60 Hz Crystal Time Base Paratronics 100A Logic Batt. 1 . resolution. Re- oper. mV and NA Kit S4.75 Converts digital clocks Analyzer Kit S199.00 sistance to 20 meg. I% accuracy. Small, _ from AC line frequency to crystal time Converts an oscilloscope Into a digital portable, completely assem. in case. 1 yr. base. Outstanding accuracy. Kit includes: tester and analyzer. Trace computer pro- guarantee. Best value ever! 559.95 PC board, MM5369, crystal, resistors, gram flow, monitor I/O sequences, etc. capacitors and trimmer. Trouble shoot all digital, CMOS and MOS Not a Cheap Clock Kit S14.95 families. 128 bit truth table (8 by 16 bits). New Cosmac Super "ELF" Includes everything except case. 2 -PC Complete with case, parts and instructs. RCA CMOS expandable microcomputer boards. 6-.50" LEO Displays. 5314 clock Model 10 Trigger Expander Kit expands w/HEX keypad Input and video output for chip, transformer, all components and Model 100A to 24 bits 5229.00. Model graphics. Just turn on and start loading full instructions. Same clock kit with .80' 150 Bus Grabber Kit 5369.00, a one the resident monitor displays. 521.95 your program using board logic analyzer for S-100 bus appli- Pushbutton on ROM. selection of all four cations. Instant access to 56 S-100 bus CPU modes. LED indicators of current Digital Temperature Meter Kit signals. Complete kit with all parts and - 1(.7 t CPU mode and lour CPU states. Single instructs. Indoor and outdoor. Automatically step op. for program debug. Built in pwr. NOW YOU CAN ADD EXTRA switches back and forth. Beautiful. 50" supply, 256 Bytes of RAM, audio amp. 8 \Profit, Volume, Traffic LED readouts. Nothing like it available. 2.5 MHz Frequency Counter spkr. Detailed assy. man. w/PC board 8 TO YOUR ESTABLISHED RETAIL Needs no additional parts for complete, less case 537.50 all Kit Kit Complete kit STORE AND GET THE BEST OF full operation. Will measure -100° to parts, fully socketed. Comp. MHz BOTH WORLDS! +200°F, air or liquid. Very accurate. 5106.95 High address display option 30 Frequency Counter 8.95; address option Complete instructions. 539.95 Low display 9.95; Kit Complete kit less case 547.75 Our Authorised Sales Centre programme is a Custom hardwood cab.; drilled front Prescaler Kit to 350 MHz $19.95 proven way to increase retail sales and profits. panel 19.75 Nicad Battery Backup Kit Choose the famous Tandy products you want to Clock Calendar Kit S19.95 w/all parts 4.95 Fully wired and tested in Stopwatch Kit $26.95 add to your line -and keep your own identity! It CT7015 direct drive chip displays date furniture, cabinet 151.70 1802 software xchng. Full six digit battery operated. 2-5 volts. you have a successful store (hardware, and time on .6" LEDS with AM -PM indi- appliance, jewellery, photo, chemist. etc.) in a club; write for into. 3.2768 MHz crystal accuracy. Times to cator. Alarm/doze feature Includes buz- town of under 20,000 Contact us NOW. A 59 min., 59 sec., 991/100 sec. Times std., minimum investment inventory and zer. Complete with all parts, power supply RCA Cosmac VIP Kit 275.00 covering split and Taylor. 7205 chip, all compo- start-up costs can begin a rewarding association and instructions, less case. Video computer with games and graphics. nents minus case. Full instruc. White or with Tandy. a leader in home entertainment and black plexiglass case. 55.00 electronics! 1977 IC Update Master Original Cosmac "ELF" kit FOR DETAILED INFORMATION WRITE OR CALL Manual All parts and instructs. 589.50 Auto Kit Clock S15.95 TANDY AUTHORISED SALES CENTRE Final 1977 closeout while Board 14.95 515.00 they only DC clock with 4-.50" displays. Uses 280 VICTORIA RD, RYDALMERE, 2116 last. 1978 Master available late Jan. 1978 National MA -1012 module with alarm PHONE: 638-6633 530.00. Complete IC data selector, 1234 Video Modulator Kit S9.95 option. Includes light dimmer, crystal pg. master rel. guide, 17,000 cross ref- Convert your TV set into a high quality timebase PC boards. Fully regulated, erences. Free update for 1977. Domestic ' monitor without affecting normal usage. comp. Instructs. Add 53.95 for beautiful postage 52.00. Foreign 56.00 Complete kit with full Instructions. dark gray case. Best value anywhere. TERMS: 55.00 min. order U.S. Funds. FREE: Send for your copy of our NEW 1978 BankAmericard and Master Charge accepted. GUEST CATALOG. Include three Shipping charges will be added on charge cards. International Postal Reply Coupon

96 ELECTRONICS TODAY INTERNATIONAL - MARCH 1978 Electronics is where it's all happening ...ifyou're into it you've got it made!

It's the world's fastest growing industry... with new discoveries...new products every day. \...12.11141 And, every day, there are more jobs...bigger salaries...better opportunities...for people who are trained. , r, You can be part of this boom now by training with International Correspondence Schools. Learn to design, build, install, test, control and maintain modern electronic equipment...from . your own colour TV or hi-fi set to a digital computer. 11 .1440 'i Your career opportunities are limitless...in broadcasting, industry, the military, aerospace . :,_ programs, medical science and communications. With your enthusiasm and ICS tuition, a well paid job and a secure future in electronics is well within C A your grasp. How do I get into it? ICS have put together a -.way FREE Electronics Career Folder. It tells you all about the many courses open to you including Find out how you can be where Communications and Broadcasting, it's all Industrial happening - in Electronics. Fill in the coupon Electronics, Computer Servicing and Audio/Radio and post today! Servicing...courses endorsed by the Television and Electronics Technicians Institute of Australia. ICS Home Post the coupon and the career folder will be on its Study way to you without obligation. Don't wait another ...your passport minute...progress won't. The big developments to in electronics are happening now and the demand success in life! MN IM Eli IM IZZ for skilled people is growing all the time. M ~ W M r. Your invitation to join the thousandsI of Special Colour TV repair course. successful ICS graduates. Colour TV is booming all overAustralia,beyond the To: International Correspondence Schools expectations of all the manufacturers, resulting , 400 Pacific Highway, Crows Nest. NSW. 2065 in a shortage of qualified people to fill the 18-20 Collins Street, Melbourne VIC. 3000 182 service gap. 1 Wakefield Street, Wellington. N.Z. You could make a successful career in this YES! 1 growing field with the help of the ICS School of Please send me, entirely without obligation, a copy of the: TV Servicing. You can benefit by this course - all 1 ICS Electronics Career Guidance Kit you need is the enthusiasm to learn and enjoy 1 ICS Colour TV Servicing Career Guidance Kit. rewarding work. 1 I MR/MRS/MISS Your ICS course could be a start of an exciting new career or you can use your new-found 1 ADDRESS knowledge to earn extra money in your spare time. 1 POST CODE This special course is endorsed by the 1 Television and Electronics Technicians Institute PRESENT OCCUPATION AGE- of Australia. I Take the first step Send the coupon today. It could be - the first 1 Fill in and mail step in an exciting new future for you. this coupon today! Is mJ276620 for the Electronic Industry ARE YOU AWARE?? THAT WE HAVE PROBABLY THE LARGEST RANGE IN AUSTRALIA OF TOP -BRAND, QUALITY PRODUCTS AT CURRENT MARKET PRICES WITH OFF -THE -SHELF AVAILABILITY.

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Service tP.0. Oti?.BOX 36 , HIGHBURY ' Phone 264-2301 DISTRIBUTORS: - CASSETTES PROFESSIONAL GRADE . , C60 LN $1.99 C90 LN 2.60 NORTH. 20 % discount for 10 or more C (l - - C.B. ACCESSORIES ouICA10.4k J. A. SEVERN PL259 Antenna Plug $1.00 (No adaptor P.O. Box 47 required) Lightning Arrestor $2.65 (connects In antenna line to C.B. Rig) N Patch Cord 1 metre of $3.00 50 ohm coax Epping 2121 with PL 259 Plug at each end Cigarette Lighter Plugs $1.00 869-1058 * SPECIAL OFFERS WHILE STOCKS LAST ADVISORY SOUTH. TAG TANTALUM CAPS 4.7µF&6.8µF25V .20 BRYAN CATT or $2.00 per dozen SERVICE AND ROTARY WAFER SWITCHES INDUSTRIES. Single Bank 1 pole 12 possitlon $1.00 2 pole 5 position $1.00 3 pole 4 position 105 Miranda Road South $1.00 4 pole 3 position $1.00 SPARE PARTS (Near Motor Registry) SOLDERING IRONS Lotring 240 V 30w $10.96 Spare Tips .58 Miranda. SUPPLIED VOLTAGE REGULATORS Phone: 524-4425 LM 340-T POSITIVE REGULATOR AVAILABLE IN 6, 8, 12, 15, 18 or 24 Telex AA27266 volts $1.70 TO TRADE INTEGRATED CIRCUITS LM 555 CN .65 LM 741 CN .50 EAST. Full WE ALSO STOCK A COMPREHENSIVE Service facilities for all RANGE OF LINEAR. T.T.L. & CMOS communications equipment. RADIO DESPATCH INTEGRATED CIRCUITS AT COMPETI TIVE PRICES CB radio, Stereo, and HiFi etc. SERVICE. POST & PACKING .60c SEND 20c STAMP FOR QUANTITY 869 George Street, PRICES OR COMPLETE CATALOGUE iJ Sydney, N.S.W. 2000 METERS elf EDGEWISE 35 x 15 mm CENTRE ZERO UNSCALED $3.75 Phone: 211-0191 EDGEWISE 35 x 15 mm SCALED 0-10. . $3.75 SQUARE 40 mm CENTRE SCALED 5-0-5 $3.50 WEST. SQUARE 25 mm SCALED 0-10 $3.10 ELECTRONIC TAG TANTALUM CAPACITORS .1, .22, .33, .47, .68, 1, 1.5, 2.2, 3.3, 4.7 (DISTRIBUTORS) ALL 35 Volt .30 6.8 35v .33 (A Division of Electronic 10 25v .30 15 16v .30 Service facilities for Enthusiasts Emporium). 22 10v .33 33 10v .39 trade and public 2-3 Post Office Arcade, 47 6v .69 LIGHT EMITTING DIODES Joyce St., Pendle Hill, Red 24 mCD 2.15 30 High Intensity N.S.W. 2145. Phone Red 6 mCDGreen 1.72 636-5222 Yellow 7 mCD .75 419-3342 CERAMICS PHILIPS 100V 1.8-39 pf NPO .10 47-120 pf NPO .13 150-330 pf N750 :14 390-1800 pf HiK .09 NEWCASTLE: 2200-4700 pf HIK .14 1000-10000 pf DIGITRONICS HIK 40v .09 ROAD RUNNER ELECTROLYTIC SPECIALS 186 Parry Street, UPRIGHT TYPES 220 µt 16v .13 COMMUNICATIONS Newcastle West, 2302 220 ilf 25v .17 470/íf 16v .17 39 Vere St, Collingwood 3066 Phone: (049) 614991 470 f 25v .22 1000 µf 16v .24

ELECTRONICS TODAY INTERNATIONAL - MARCH 1978 99 390 )7 6 n0 )60 »0 IC i HA reo DO ]] 0 AVATEUR & SWL COVVU\ICATIO\5 )10 090 )90 Ionospheric Predictions for the month of April ]70 7/0 NO THESE PREDICTION GRAPHS have been prepared courtesy of Amateur Communications ]00 by Prediction Service Division of the NO Advancements from predictions supplied the Ionospheric 00 Department of Science. )) 0 210 The graphs indicate the maximum usable frequency (MUF) on HF circuits between various 200 in and selected overseas. 100 centres Australia points 170 For less than 50% of the days of the month the highest frequencies propagated will be at least no 160 as high as the uppermost curve. Between 50% and 90% of the days of the month the MUF will be 190 least as as beneath upper curve. The absorption limiting frequency 14 0 at high the curve the (ALF), no which affects the lowest frequencies that will be propagated, is indicated by the lower curves on 1)0 11.0 the graphs. 100 Time is given in Universal Coordinated Time (UTC) along the horizontal axis. .0 90 Frequency is given in 1 MHz increments up the side of the graphs from 2 MHz to 40 MHz. ,0 metre is so 67 Where the MUF exceeds the upper limit of the graph, six propagation indicated, 90 VHF enthusiasts take note. .o )0 Note that areas adjacent to the points given for each prediction chart will experience similar ]0

propagation. For example, Canberra and SW NSW amateurs and SWLs may use the Sydney -Tokyo 1] 10 ). chart as a guide to working surrounding Asian areas such as Korea, Hong Kong and the nearby island chains. The Sydney -Ft. Collins chart may be used to indicate propagation to central and PERTH -FT COLLINS south USA. LENGTH 16257 KMS

400 400 290 Mo 270 M 250 LO )) 0 )) 0 )1 0 )00 %790

)10 .TO ]40 }I 0 ]00 ]20 210 200 190 110 1)0 140 00 140 130 1]0 nu 100 90 90 ,0 00 60

30 )0

MELB-FT COLLINS SYDNEY -HONOLULU MELB'NE-HONOLULU BRISBANE -TOKYO LENGTH 14143 KMS LENGTH 8203 KMS LENGTH 8879 KMS LENGTH 7156 KMS

JOG o o b0 10 x0 ]10 )10 0,0

110 l5 H0 ). 0 uo 00 330 Alt uo )) 0 )10 210 At wo 300 )]0 AO 7110 010 MO ]) 0 ])O ]r 0 )v0 200 190 ] o no ].0 1.0 No 230 a] 720 720 no no 210 mo )10 AO AY AO

100 1 0 too 170 170 170 170 vo vo 140 100 140 I,0 1110

]0 1)0 1'] 0 1)0 )0 100 110 110 110 100 .100 00 90 00 90 00 00 00 )0 lo ,O 10 00 00 00 60 40 10 .0 aA 00 )0 )0 20 - 70 )0

0 1) 00 1 ] . N03 12 17 SYDNEY -TOKYO ADELAI DE -TOKYO ADEL-HONOLULU ADEL-FT COLLINS LENGTH 7822 KMS LENGTH 7853 KMS LENGTH 9206 KMS LENGTH 14502 KMS 100 ELECTRONICS TODAY INTERNATIONAL - MARCH 1978 1

b0 .o wo 11U vo 100 UV NO 310 UO UO 1} 0 NO 310 ]10 300 100 290 AO A0 Ao })0 770 AO A0 no no NO 730 no 210 no ]10 No 200 Ao 190 190 1110 190 ,10 90 170i 10 ,0 0 UO 130 1}0 1}0 110 110 100 90 90 90 110 10 10 110 90 90 90 90 9a ]0 00 }0 00 I 00 BRIS-HONOLULU BRIS-FT COLLINS SYDNEY -FT COLLINS MELBOURNE -TOKYO LENGTH 7610 KMS LENGTH 12902 KMS LENGTH 13434 KMS LENGTH 8190 KMS

]10 32 No x A0 No .] 110 su uo 00 no 010 }00 A0 290 AO AO JO })0 }l0 AO NO A0 ).0 No 90 no n'l }} 0 nl }10 213 AO AO I\0 190 190 tea vo 10 Iso no 1110 140 1.0 130 uo uo 120 110 110 100 100 90 90 .0 00 10 10 ao 110 110 110 40 30 30 10 }0 1 I I m 1} r TOWNSVILLE-TOKYO T'VILLE-HONOLULU TOWNS -FT COLLINS PERTH -TOKYO LENGTH 6144 KMS LENGTH 7558 KMS LENGTH 12873 KMS LENGTH 7922 KMS

400 SWL COVVU\ICATIO\S 00 }}0 ]10 1900 on 17850, 15115. 11870, 100 DX news from Sri Lanka. GMT "Radio Monitors International" is a 15 9720 and 7190 kHz. 0315 GMT on minute DX programme broadcast each 15425 and 9720 kHz. Sunday in the Overseas Service of the Sri Lanka Broadcasting Corporation. Norway broadcasts. The programme consists of three seg- Radio Norway's schedule current until ments: a station profile, a report on a May shows the following transmissions technical topic, and DX Digest in which at convenient times for listeners here in listeners reports are acknowledged. Australia 0700-0830 GMT to Australia Radio Monitors International is and New Zealand on 11850 kHz, and to 110 100 prepared in India by the host, Adrian the Far East on 11895 and 15135 kHz. 90 Peterson, and reception reports will be 1900-2030 GMT to the Pacific on 9610 10 110 welcomed at the programme address, kHz. 0500-0630 GMT to the Pacific 110 Box 15, Poona, India. All correct on 9645 kHz. All Radio Norway's 30 }0 reports are acknowledged by a fully programmes are in the Norwegian detailed verification card. Times' to hear language; except for the last half-hour PERTH -HONOLULU the programme are: 1100 GMT on of the Sunday broadcast, when an LENGTH 10967 KMS 17850 kHz, 15120 kHz and 11835 kHz. English language segment is aired. ELECTRONICS TODAY INTERNATIONAL - MARCH 1978 101 An interesting item in the' Kemtrontc Hy -Gain were represented in Aust- accessory range is a mobile noise supp- ralia by O.B.C. International Marketing NEIAIS ressor kit, model 36-106 which includes P/L who were placed in the hands of CB power lead filters for the transceiver, a receiver late last year. O.B.C. were a Kemtronics rigs and accessories ignition coil points, suppressor capacitor, division of the Luxor corporation. Lawrence and Hansen, claimed to be generator/alternator suppressor etc. Executives from O.B.C. have declined Australia's biggest electronic. electrical The range of Kemtronic's antennas to comment. and instrument retailers/wholesalers, includes the usual centre -loaded magnet It has been reported that the collapse have introduced a range of CB rigs and base, magnet base rubber duck and of Hy -Gain in the U.S. and their agent accessories under their Kemtronic brand bottom -loaded trunk lip mount here will affect the supply of spare parts name. antennas. for Hy -Gain equipment. However, this is The transceiver line begins with the Also included are two helical whips. only likely to be significant in the long CB500 economy AM rig. The model 33-103 is 1.3 metres long term. Apparently there are sufficient This little 18 channel rig has the and has a slug tuning adjustment on the stocks to supply needs for the immediate minimum of controls plus an S/RF tip - no more chopping bits.off - oops, to medium -term future. meter and features a mic which plugs too far - catastrophes! Amtronics International have taken into the front panel. The model 33-114 is a 1.5 metre over the Hy -Gain agency from O.B.C. Top of the Kemtronics line is the helical with a short adjustable whip - International Marketing here in SSB1000, an 18 channel SSB/AM rig section on the top for adjusting the Australia. with an RF gain control, ANL and NB SWR. No cutting problems with this one circuitry, and a large S/RF meter. The either. mic also plugs into the front panel. Also worth mention is the model The accessory line includes a range 33-112 antenna. This is a fibreglass, of three SWR/Field-strength meters. top -loaded whip - the type claimed to The -smallest (model 30-100) is a give the best performance of all loaded simple hand-held meter that measures mobile whips. only SWR and field strength on any It has a short adjustable whip on top frequency between 1.5 MHz and 150 for tuning the antenna to the lowest MHz. SWR. Next in line is the 30-102 model, a A range of antenna mounting access- fairly conventional SWR meter that can ories is also available along with coax also be used to measure power and field cables and an anti -theft transceiver lock- - 1 strength over the same frequency range. ing bracket. It features a large meter with an Further enquiries, brochures etc easily read scale. available from Lawrence and Hanson's Top of the Kemtronics meter line is head office at 142 Dorcas St, South the 30-103 which measures,SWR, power Melbourne, 3205 (697-1599). and field strength and also includes an is antenna tuning unit. The 30-103 Philips UHF CB release in March obviously intended for base station use. Philips will release their UHF CB, the a Two microphones, noise -reducing FM320, late in March. It is expected The latest preamp base mic from Turner - the Expander. type and a unidirectional type, are to be on sale early April in Victoria included in the accessory range along and NSW and later that month in the with an extension speaker. other states. The The long awaited UHF FM rig Expander features 40 channels, digital LED The `Expander 500' is Turner's readout, automatic channel stepping newest pre -amplified base station micro- It volume and small size. It will come with a six phone. features separate and warranty and is tone controls, built-in meter for reading + month expected to retail at around $330. both audio input and bettery condition t) Wibuibirutomc and includes a six -wire cable making the Expander 500 compatible with all Hy -gain transceivers. Bankrupt Compression circuitry compensates We learned shortly before going to for varying mouth -to -mike distance and press that Hy -Gain in the United States speech characteristics and reduces over - The Kemtronics basic 18th AM rig, the have filed for bankruptcy. modulation distortion. CB500 (top) and combination SWR/FS/ sliding volume power meter and antenna tuner, model Despite obtaining extended finance The control adjusts 30-103 (bottom). late last year following a disastrous the audio input for full modulation. The $(US)24 million loss over the 1976-77 tone slider control adjusts the bass - financial year, Hy -Gain have been treble balance for maximum speech unable to make headway with their CB clarity.

. , . product lines. A push -to -test button shows battery Hy -Gain Supported E.F. Johnson's condition on the dual -function meter. The microphone head tilts for ..... bid to have the U.S. International Trade L; Commission put import restrictions operator comfort. swot otowfot a on Japanese manufactured CB trans- For further enquiries, contact ceivers they claimed were severely Communications Power Inc., on (02) .. affecting market prices in America. 357-2022 or (02) 36-3703.

102 ELECTRONICS TODAY INTERNATIONAL - MARCH 1978 THE WORLD LEADERS IN VHF NOW BRING YOU THE ULTIMATE

.1111111111 .1111111111 "dim. a _inn, re -«

.S. . . o.r W W. won ...... r _ .0rov «. » v.. »

/" °J+ , r `. 0 0 0 ,...

1C701 ICON'S DIGITAL ALL SOLID STATE HF TRANSCEIVER V ICOM now brings you the latest in solid-state technology - the 1C701 transceiver. Features as standard (and NOT optional): Built-in twin VFOs, wide and narrow cw filters, variable output power, digital readout. Frequency control is LSI based with 100Hz steps via an optically coupled VFO. Frequency coverage of the transceiver is from 1,8 thru 10MHz covering the six Amateur bands (27 MHz band is not included nor has any provision been made for adding it!). The receiver has a number of interesting features including double balanced Shottky diode mixers in a triple conversion super - het with continuous bandwidth control. The features just go on -and -on! Give us a call now for full specifications and the ICOM catalog.

* All Solid State, even the finals. * 100W Continuous Duty on All Bands, All Modes. * All Bands 1.8 30MHz. * USB, LSB CW; CW-N(Narrow), RTTY. * Double Balanced Schottky Diode Mixer used in both receive/transmit. * Dual built-in individual Digital VFO's offer split frequency operation. * ICOM's unique Pass Band Tune. * VOX, Semi break in CW, RIT, AGC, Noise Blanker. * Built-in Speech Processor. * Full Metering. * Extremely compact. ICOM * Digital readout and all filters built in. * Built in DC power supply. *. Optional AC power supply/speaker. * Full line of accessories to come.

The IC -701, the one you've waited for, the ULTIMATE Distributed by:

VICOM GROUP OF COMPANIES Adelaide: 43.7981 Canberra: 82.3581 139 AUBURN RD. Perth: 446.3232 Brisbane: 38.4480 AUBURN VIC. 3123 Gold Coast: 32.2644 PH. (03) 82 5398 Melbourne: 813.2355 MICROCOMPUTERS SEMCON PTY. LTD. ATTENTION MOTOROLA D2 SCALAR UHF/CB If you want a fstemoyou OWNERS! expandable system, you need: 8K BYTE, STATIC ANTENNAS MEMORY CARD FOR = Australian Designed and Built CITIZENS BAND Fast Access 350 ns Chips (2102LF) RADIO Low Current -- 1:3 Amps Motorola Bus Compatible DESIGNED AND MANUFACTURED IN AUSTRALIA ealitlessie Write Protect Parity Generation/Checking available SCALAR'S UHF Professional Finish MOBILE MOUNT FOR CORRECT fiR k TERMINATION OF CO -AX 3óa ,ck Plated through Holes to AT UHF FREQUENCIES - $275 assembled board PAT. PENDING $219 in kit form No. 20506/76 n 298 Assembled with Parity $110 for 8k kit without rams

. Built Boards Guaranteed 12 months CARD CAGE/BACKPLANE: MODEL OB o Designed for Motorola Cards Anodised Aluminium chassis Sturdy Construction e Tin Plated Backplane CB420 Accomodates 8 cards HIGH PERFORMANCE DUAL BAND $74.00 476 AND 27 MHz MOBILE CO -LINEAR WHIP EDGE CONNECTORS - GAIN AT 476 MHz 4.5 dB 43 x 2 x 0.156' $8.50 each OVERALL HEIGHT 42' Eight for $59.00 S100 Connectors $8.50 THIS MONTHS SPECIALS 555 TIMER 35 cents

16 PIN DIL SOLDER IC SOCKET 28 cents CB410 HIGH PERFORMANCE 8 T26 $2.30 4.5 dB GAIN MOBILE WHIP. REQUIRES NO 2708 $18.50 2102 LFPC $1,90 TUNING. OVERALL - HEIGHT 21" 1 Amp Positive Regulators 10220 $1.20 LOW POWER SCHOTTKY

74LS00 33 74LS38 40 74LS109 53 74LS02 33 74LS40 37 74LS138 1.20 CB420 74L0S4 34 74LS42 1 30 74LS160 1.20 74LOS05 37 74LS47 1.30 74LS161 1.20 CB470 GDB GAIN CO -LINEAR BASE ANTENNA. ENCLOSED IN 74LS08 33 74LS74 0.55 74LS174 1.00 FIBREGLASS RADOME. LENGTH, 8ft. 74LS09 33 74LS75 0 70 74LS175 1.00 74LS10 33 74LS85 1 58 74LS190 1.20 A WIDE RANGE OF SCALAR IJHF/CB AND 27 MHz ANTENNAS 74LS11 33 74LS86 0.60 74LS191 1.20 CB (FROM 30" to 108" LONG) AND ACCESSORIES ARE AVAILABLE 74LS13 80 74LS90 1 20 74LS192 1.20 FROM LEADING RETAILERS AND DISTRIBUTORS THROUGHOUT 74LS14 1.40 74LS91 1.20 74LS193 1.20 AUSTRALIA. 74LS20 33 74LS92 1.20 74LS367 80 74LS30 33 74LS93 1.20 TRADE EÑOUIRIES WELCOME. SCALAR INDUSTRIES PTY LTD I.C. SOCKETS LOW PROFILE COMMUNICATION ANTENNA ENGINEERS - 18 SHELLEY AVENUE, KILSYTH, VICTORIA 3137 TELEPHONE 7259677. SOLDER DIL - TIN I WIRE WRAP GOLD, CABLES WELKIN TELEX AÁ34341

8 25 22 35 24 1 40 14 35 24 45 14 70 NSW: 20 THE STRAND, PENSHURST 2222. TEL: 570-1392 16 28 28 50 16 70 OLD: 969 ANN ST, FORTITUDE VALLUE, OLD 4006 TEL: 52-2594. TELEX AA43007 18 35 40 90

104 ELECTRONICS TODAY INTERNATIONAL - MARCH 1978 12" 3 -WAY 75 -litre 80 W Handling TIMBER VENEERED ENCLOSURE COMPLETE KIT D$139PAIR COMPLETE $189 PR. 10" 3 -Way 75-litre 70 Watts HANDLING

KITS 1 09 PAIR COMPLETE $159 PR.

10" 2 WAY 50 LITRE 60 WATTS. KIT $89 PR. jjoMPLETE $129 PR. 8" 2 WAY 30 LITRE 40 WATTS KIT $75 PR. COMPLETE $102 PR. HI Fl SPEAKERS & KITS DIRECT FROM MANUFACTURER 75 -litre cabinets KIT $48 pr . 00

80 COL CARD PRINTER/PUNCHES 50 -litre cabinets KIT $40 pr 7/9 TRACK TAPE DRIVES KIT $35 132 COL. DRUM PRINTERS 30 -litre cabinets pr POWER SUPPLIES, DISK DRIVES, each ETC. DISCO LIGHTING SYSTEMS & CONSOLES P.A. BINS COMPONENTS, AMP ETC MADE TO ORDER YOUR DESIGN OR OURS PLEASE 0.90'1 CAPACITORS, WRITE FOR QUOTE RESISTORS, ETC. POWER, All orders forwarded by road LOW 650 ns ACCESS TIME NO REASAONABLE transport payable on delivery OFFER REFUSED BRAND NEW, ALL CHEQUES & MONEY ORDERS TO AUDIO SPECTRUM FULLY GUARANTEED!

Cc UCHlo spectrum MAILMAN 41 WHITEHORSE ROAD DEEPDENE 3103 ELECTRONICS P.O.Box 536 Lane Cove 6 Lang Rd,Kenthurst Sydney Ph (03) 80.1074 or PH: (02) 498-3405 A.H. (03) 488821 Ph: Bus 848-9133 TRADE ENQUIRIES WELCOME, A.H. 654-9050

ELECTRONICS TODAY INTERNATIONAL - MARCH 1978 105 Buying components can be great fun, especially when you only want 16 IC's from one manufacturer and 10 from another and a few 10W resistors ~1E~ and a couple of connectors CITY and Purchasing is too busy to ELECTRONICS write out 6 fiddly little orders Bal and then the relay supplier PHILIPS - LOCMOS

HEF 4000 .30 NEF 4021 1 28 NEF 4050 5(1 HEF 4082 .32 reckons ,you're joking when you HEF 4001 30 NEF 4022 122 NEF 4051 124 NEF 4085 94 HEF 4002 30 HEF 4023 .30 NEF 4052 124 HEF 4086 94 HEF 4006 128 HEF 4024 .99 NEF 4053 114 HEF 4093 96 say need one in a NEF 4007U8 30 HEF 4025 .30 HEF 4066 80 HEF 4510 34 hurry and NEF 4008 HEF HEF you 4511 124 4027 .57 4068 33 NEF 76 NEE 4011 .30 HEF 4028 99 HEF 4069U8 35 NEF 4512 86 NEF 4012 30 HEF 4029 150 HEF 4070 .32 NEF 4516 76 he only takes orders in hundreds HEF 4013 50 HEF 4030 52 HEF 4071 30 NEF 4518 56

NEF 4014 128 HEF 4035 1 28 HEF 4072 32 HEF 4519 74

HEF 4015 1 24 NEF 4040 1.37 HEF 4073 32 HEF 4520 41 and then while you're wondering HEF 4016 52 HEF 4041 99 NEF 4075 32 HEF 4528 02 HEF 4017 1 24 HEF 404? 1 96 HEF 4076 1 86 NEF 4531 2 74

HEF 4018 1.28 NEF 4043 1 24 NEF 4077 39 HEF 4539 1 12 how the hell you're going to get HEF 4019 73 HEF 4044 1 24 HEF 4078 32 NEF 4555 1 02 HEF 4020 1 41 NEF 40464E 292 NEF 4081 30 HEF 4556 102 the circuit together, you're GENERAL ELECTRIC Electronics SCR's TRIACS & MACS UJT's & PUT's thumbing through .8A 4009 C 1038 200V 1.14 SC1410 104 1.95 282646 1.24 C 10601 4A 400V 1.19 SC I5I015A 4009 1.37 262160 3.65 C 1220 BA 400V 2.11 ST2 33 01311121160281 188 Today and you see this advert C 122E 8A 5008 2.54 ST4 .60 0131212860271 1.18 for a crowd that can supply all signotics TTL LOW SCHOTTKY

the parts and aren't put, off by 741500 36 741330 36 741.374 49 741S93 123 741.50? 36 741542 142 741578 47 741395A 1 70

741.304 .38 741351 36 741565 1 99 7415164 1 76 quantities large or small 741S10 36 741.555 36 741586 56 741S196 1 70 the 741373 47 - - 741.520 36 741390 173 741S367 1 19 and are small enough to care and signotics LINEAR Transistors Polyester Film 100V Caps 2N3055 including complete AC117 65c capacity ul I ea 10 ea mounting kit and T03 they've even given you. their AC128 65c 001 -DI 8c 6c UA 741 56 transtslor socket AC187 65c .012 - 033 10c 7c LM 301 56 AC188 65c 039 - 056 I 2c S1.10 set lM 308 143 9c 068-.18 I4c I0c number 381 telex and they might IM 3.04 B0137 60c .22-.33 I8c I5c LM 382 269 80138 60c 0.5 ohm 5W 39- .56 22c 18c 80139 65c wirewound resistor 68 - 82 28c 24c just be the people to call and .... TIMERS 80140 65c 20c ea. BC547 22c NE 555 64 BC548 22c IN4003 phew ! NE 556 1.43 BC549 22c Crossover Caps. IA 7000 diode BC557 22c REGULATORS 8C558 Poly Film 100V 5c ea. CLIP THIS OUT YOU NEVER KNOW WHEN 1OU'L7. RE,VELl /NG US ir 22c BC559 22c LM 309A 2.56 I mid 42c 3.3mId 1.10 uA78CB 2.10 1.5mld 55e 4.7mId 1.50 NZ Mal LM 340T1V1 263638 I8c 1380 2A CB ren lM 723 .65 2114258 18c 2.2m1d 75c 6.8mId 2.10 ea. CAPACITORS, SEMICONDUCTORS - Fairchild, ITT, UA 78CUIV1 2.10 MJE3055 80c S2.45

National (NS), NEC, Motorola Philips, Plessey, RCA, Pin for Pin substitute may be supplied where original not available Signetics, Texas. RELAYS - National (Japan), ITT. P 8 P semiconductors only 60c orders including cable etc. 5280 CONNECTORS - Acme/Kings, ITT/Cannon. HEATSINKS -Delco, Philips, Thermalloy. Gold Rush Specials RESISTORS - AIL Beyschlag, Philips, Soanar. TRANSFORMERS - Ferguson .. . PLUS MORE -11-111 i 2V Relay 1Double Pole CtD PCB

. $2.50 Orders:(02)6366052 , ) PHILIPS AD8080/M8 6W 8n 36.65 Office: (02)636 6222 8" Twin cone loudspeaker

Telex: ÁA23343 H P.O. Box 623 Electronic (Distributors) Ballarat Victoria 3350 2.3 Postla Office Arcade, =I- Joyce Street, PENDLE HILL. NSW. -2145. - ELECTRONICS TODAY INTERNATIONAL - MARCH 1978 Ideas for experimenters These pages are intended primarily as a source of ideas. As far as reasonably possible all material has been checked for feasibility, component availability etc, but the circuits have not necessarily been built and tested in our laboratory. Because of the naturé of the information in this section we cannot enter into any correspondence about any of the circuits, nor can we produce constructional details. ESTABLISHED FOR THE Electronics Today is always seeking material for these pages. All published PAST 35 YEARS FOR material is paid for generally at a rate of $5 to $7 per item. - ALL YOUR Ar o REQUIREMENTS 3045 30u5 NOTE

ICI IS a01/ 101 IC2 IS 4024 224m5+ « 2.24ms STILL ON TOP IC3 IS 4082 ELECTRONIC UNITS 1'^ TO. .110 T DECADE COUNTING UNITS T I 1 1 1 Hz WIDE BAND AMPLIFIER 14 13 12 10 9 6 1a 13 12 10 9 FOR your counter 1 MV sensitivity, ICI IC3 band width 1-250 MHz.

6 1 2 3 4 5 6 7 DEVOTED EXCLUSIVELY TO L L_ THE MANUFACTURE OF 2291 PIEZO ELECTRIC CRYSTALS 15OP o OUTPUT OV Federal & State 20P Contractors to o Government Departments. A perfect.... divided by 149 and doubled to give As any orchestral player knows, a 439.8 Hz, an error of only 0.05%! II >4 "4: 440 To enable a division of 149 be source of Hz, perfect or standard to y A is essential if he is to be in tune. On obtained, a dual AND gate is used. The 1 many occasions a piano will not be first gate detects the 149th pulse, and . available - hence this circuit. the second resets the binary counter on In the following a standard crystal the 150th pulse. at 32.768 kHz is used to stabilise an The resulting 30us pulse may be fed Yr oscillator. This frequency is then to a suitable amplifier. "All Types of Mountings"

REPRESENTATIVES - a piecé of silver foil is Bite Detector In operation, NSW Hose & Equipment Co. folded over the line, and placed between Pty Ltd, Since there are many fishermen in the the LED and the LDR. When a fish 11 Salisbury St., country, there must be many, who like 2019 pulls on the line, the foil will jump up, Botany, myself, try to combine their hobby Phone 666-8144 and light will shine on the LDR, causing with electronics. S.A. Rogers Electronics the resistance to go low, firing the SCR. this circuit is for a simple bit de- P.O. Box 3, Even if the foil drops again, due to its Modbury North, S.A. tector, and construction of such a unit latching action, the SCR will remain on. Phone: 42-6666 represents a considerable saving over the WD1 will now emit a loud note, and buying of a commercial instrument, OLD Fled Hoe & Sons Pty Ltd, the unijunction transistor, Q1, acts as a while at the same time offering many 246 Evans Road, relaxation oscillator making LP1 flash Salisbury North, Brisbane, additional advantages. Phone: 47-4311 OFF RESEI (the rate of flashing being dependant on the setting of RV2). SW1 is the on/ W.A. Communication Systems, reset 32 Rudlock Road, off switch. Morley 6062 The setting of RV1 will depend on Phone 76-2566 the amount of light reaching the LDR TAS. Dilmond Instruments, under quiescent conditions. The circuit P.O. Box 219, is, if anything, too sensitive and in Bellerive, Hobart, Tas. strong winds or heavy currents, Phone: 479-077. additional weighting of the line may be Send stamped addressed necessary, in this case lead foil should envelope for new catalogue or quote for your requirements. be used. WD 1 and LP1 may be taken from the BRIGHT STAR CRYSTALS P/L. unit via an extension lead, and kept by 35 EILEEN ROAD, CLAYTON, the anglers tent or sleeping bag. The VICTORIA, 546-5076

Continued on page 109.. .

ELECTRONICS TODAY INTERNATIONAL - MARCH 1978 107 DIRECT FROM USA MOTOROLA `pIEZO' SUPER HORN has all the features! Needs no cross -over network. Frequency response 4.000-30.000 Hz 3 dB patented momentum drive principle. No voice coils or magnets. High internal Impedance. Adapts to any system. High acoustic output. Many can be connécted in series to form an array -increased output. Power handling capacity 25 volts RMS. i' ! T SIZE: 348 x33 3x218 4 OHMS 100 WATTS Trade Enquiries Invited

Retail price As used by many major musical equipment manufacturers. $16.00 * P&P $1.00. Available through your local Hi -Fi, Electronic component or Music shop or direct o.

Victorian Distributor; Sole Australian Importer S si th Australian Distributor; ZEPHYR PRODUCTS SYSTEMS 70 Batesford Road FREEDMAN ELECTRONICS PTY LTD. 37 nga°SLtree Chadstone VIC 3148 Adelaide, SA Tel. 568-2922 89-91A Liverpool Road, Summer Hill, NSW 2130. Tel: 797-9941 - 797-0986 Tel. 212-3993.

31 BURWOOD RD, BURWOOD, SYDNEY, 2134. SEDGE CLCCTRV Tel: 747 2931 THE SPEAKER KIT SPECIALIST A.W.A. Coral *HUGE SAVINGS 12SAI 30W RMS *. 10SAI 25W RMS 8SA1 18W RMS 6SAI 15W RMS on PHILIPS KITS 111=s:111=s: 12SA5 30W RMS l OSAS Improved 25W RMS 8SA5 18W RMS PHILIPS PHILIPS HURRY - 12SA7 40W RMS 105A7 Dome Series 30W RMS LIMITED STOCKS 8 SA7 20W RMS 12" 3 -WAY 10" 3 -WAY AD12K12) WOULD USUALLY BE (similar to PRICED ABOUT OUR Plessey NORMAL 4-1-95 Foster PRICE 3016 12" 3way 40W RMS $149 3003 12" 3way 40W RMS szttS 2503 10" 3way 40W RMS PHILIPS 2510 10" 3way 30W RMS 2 -way 8" system 2010 8" 3way 20W RMS 15)5 2006 .8" 2way 12W RMS $199 $99 NOTE: THESE ARE GENUINE SPECIALS OVER 20 DIFFERENT SPEAKER KITS NOW'STOCKED THERE ARE SOME HUNDREDS SLIGHT MARKS ON OF DIFFERENT SPEAKERS SOME CABINETS CROSS-OVERS, CABINETS AND ACCESSORIES BUT BE QUICK

108 ELECTRONICS TODAY INTERNATIONAL - MARCH 1978 Ideas for experimenters UNIQUE ... from page 107 ELECTRONICS unit may be built onto a rod rest and even as a device to tell you when the cat should be fully wa terproofed. has come in! SECURITY The device has other applications; it WD1 should be the type of device may be used as a burglar alarm with a that draws a continuous current once CO. P/L. "trip wire" type detector, or perhaps energised. 682-3325 A new shop catering

/7 for the hobbyist, CB'er

FLASHER LEFT and for the trade. UNIT INDICATORS +I:V We specialise in: 0 Ce" 01 Components Kits 13E1,51 Technical Books 02 2N3055 Burglar alarm equip. CB Club needs. WARNING LAMP We have a range of data RIGHT books for your use or INDICATORS - purchase your own copy. trailer is being towed) a more powerful Hazard Warning Flasher flasher unit is required. As 02 carries We stock a full range Hazard warning lights can be a life-saver the full current of the right hand of security equipment in motor vehicles. But the high cost of indicators (3.5A to 5.25A) it must be Installation companies mounted on a suitably large heatsink. commercial units prevents some people check our prices. from fitting them. The circuit I have This can be achieved by fitting the devised is both simple and inexpensive circuit in an alluminium case 4" x 3" x to install. 11/4" and mounting 02 directly using a If you are having technical A flasher unit is used to operate the mica shim and rubber bushes to isolate problems with your equip- left hand indicators. At each flash a it from earth. The flasher unit should be ment current of 5mA is supplied to the base mounted on the outside of the case for in have a of 01, switching it on. The emitter ease of replacement. drop and chat, now goes high switching on Q2 which The circuit shown is for negative perhaps we can help you. connects the right hand indicators. If earth, but is easily adapted for positive more lamps are to be lit (i.e. when a earth vehicles. If you don't see what you want displayed, please ask

When a NPN transistor is being tested us, we can probably obtain NPN-PNP Indicator the collector will always be near OV and it for you. The 2 inverters IC1a and IC1b form first when a PNP transistor is being tested a multivibrator running at approxi- the emitter will always be near OV. MAIL ORDERS WELCOME mately 2 kHz. The next two inverters The last two inverters detect which which YOUR TO buffer the multivibrator outputs, terminal is held at OV and drive the SEND ORDER then go to the collector and emitter of appropriate LED via the current limiting P.O. BOX 402, the transistor under test. resistors R4 and R5. PARRAMATTA, 2150 the The signal applied to the base of The six inverters needed are all transistor is always in phase with the contained in a single IC package - the TRADE SALES WELCOME whether PNP collector so the transistor, SN 7404. of NPN, will always be turned fully on ó half cveJ every cch Burnett Street c Fowler. Road i<' z

383 MERRYLANDS ROAD, (CNR. BURNETT STREET) MERRYLANDS, N.S.W. 2160 682-3325

ELECTRONICS TODAY INTERNATIONAL - MARCH 1978 109 Blob Board - Mr. Blob says "The Technique of Inserting components on one side of a board and for soldering on the other is done for reasons which are now completely out of date; Namely this technique was established originally because heavy and bulky components were used. This no longer applies and has big disadvantages, the circuit is impossible to follow Digital Electronics by Unless the board is continually turned over to Inspect each side, Its difficult to work on both sides of the board and soldering basically needs three hands. A common fault is to Experiment mount both leadout wires on the same tract. Blob - Boards give you the modern, low cost, easy to build circuits. Blob - Boards are roller tinned circuit boards on which each roller tinned copper track is Identified by the letter and or number system. Simply tin the end of the component, butt the component lead against the roller tinned track, apply a blob of solder and the component is blobbed into place. All construction is from one side, component locatiol could not be simpler, YOUR NEAREST soldering is much easier, sub -circuits can be tested, then assembled together, the plain BLOB DEALER? side of the Blob -Board is free and so the Blob -Board can be mounted flush on case walls. And they can be re -used simply apply a soldering iron to the Blob and remove the THAT'S EASY. component." WRITE TO: Now start Digital Electronics by Experiment. No need to lose your way round a circuit board that needs a layout drawing - Blob -Boards make construction easy. Blob -Boards have numbered tracks that make BLOB BOARD layout drawing out of date, the tinning ensures easy soldering, and the tracks don't strip ASSOCIATES off when you unsolder components. Blobbing components on to the tracks (no holes, no drilling) makes layout easy to follow. Use the 8 -IC board for 'Digital Electronics by P.O. Box 23, SURREY HILLS, Experiment' in this issue, but remember that we have "A Blob for every job". VIC. 3127. or RING (03) 89-1019.

gau I : s - - kers are now available in A L. ,ralla DEALERS: VIC: Zephyr Prods., Sam Music, Dynasound, Dane Amp Sales. NSW: Farrell Music. QLD: Brisbane Music Factory. Trade enquiries to IMPORTRONICS, (03)317 7977.

End noise and cross -talk with our exclusive

NoiseguardTM system ( dpa( its 211 ;(moon, tnr rJgt ( canner tor,

I dge (onne< tor, S-100 typ(. -' S ,pd( utg Available front Ihrnklr Toy, or Ma,tente Shielding f very signdI toll ,lurks

t d by both inter( none( I ed ground lin,. Termination A( tuve termination of The WünderBussT each line I A product of Morrow's Micro -Stuff for network include, I Mlle 1 op amp, 2N 19114, 2N {91x, TIP29 and TIP 10 trams, tors 2 4 volts, 1811 ohms

--' A DIVISION F COMPUTER BITS STATHAM PTOY. LTDMATION 47 Birch Street, BANKSTOWN N.S.W. 2200 Phone (02) 709-4144 Telex AA26770

110 ELECTRONICS TODAY INTERNATIONAL - MARCH 1978 Ideas for experimenters -ELECTRONIC DISPOSALS +9V, 16mA 297 Little Lonsdale St., Melbourne,3000 D3 Phone 663-1785 ti~ TIL209 AWA Solid State TV Tuners $7.50 ea. D4 AWA Thorn Valve TV Tuners $5.00 ea. 1N4001 EHT Stick Rectifiers 13KV, 18KV, 20KV 75c ea. Cl D1 R1 Plessey 8" 10W 812 or 1512 $6.50 ea; R7 L 10u+ OA91 10k 4" 8$l $1.50 ea. Many other types in 0-1. 620R stock. 12V DC5 S2 Solenoids $2.00 ea. 12V AC Min. Relays 5 Amp. $1.50 ea. Slide Pots. 20K to 3meg. Singles 35c ea. R2 RO Dual 60c ea. C2 02 1k 620 R Resistors. Most values % to 1 Watt. 3c ea. 10u 0A91 Carbon Pots. Most values 30c ea. Duals 60c ea. 05 resistors 100 mixed $1.50 1N4001 Skeleton Preset Pots 10052 to 3 meg. 8c ea. Green Caps .001 to .022uF 5c ea. 'NIL D6 TIL209 .033 to .22uF 15c ea. .47 to .68uF 20c ea. Capacitors. Many Types OV Polystyrene 5c ea. Disc Ceramics. Large Range. 5c ea. Stereo Balance Meter Disc Ceramic capacitors 100 mixed $2.00. One of the more irritating aspects of and the resulting dc voltages are applied Polyester Capacitors. Large Range. Up to owning a stereo system is the need to to the inputs of the IC. 1.5uF 250V 10c to 25c ea. keep both channels 'in balance. What The output voltage from the IC1 is New Desk Telephones - Grey. $15.00 ea. 6.8uF and 3.3uF the the LED's D3 and D6 Polyester Capacitors often sounds right when adjusting applied to 60c ea. 2.2uF 40c ea. Tantalum Capac- controls turns out wrong when via the current limiting resistors R7 itors. Good range 15c ea. resuming , one's normal listening and R8, and the diodes D4 and D5.. BC. 107 Transistors 10c ea. position. These latter components allow the 0A636 600V 2A Fast Recovery Silicon LED's to extinguish at extremes of the Diodes - TV Type 25c ea. This circuit offers a solution to this IC's voltage swings. Dual 100 12 3W Wire Wound Pots. problem provided that one's equipment To use the indicator, switch the S1.25 ea. is fitted with a stereo/mono mode amplifier into the mono mode and S.C.R. BT100A 300V 2AMP 60c ea. switch. Triacs. 2AMP 400V 60c ea. adjust the balance control until both 2N3055, 90c ea. AD149, S1.00 ea. is used as a are equally illuminated. The IC1, a 741 op amp, LED's AY8110, 80c ea. 0C912, $1.00 ea. L R signals cari now be switched back into differential amplifier. and amplifier AY8139 and 9139, 45c ea. IN914 diodes across the speaker stereo mode and will, be found to be in are taken from 10c ea. 5 amp AC panel meters $3.50 ea. these perfect balance. terminals. D1 and D2 rectify 2500 uF 35V P/T electrolytics, 60c ea. 2200 uF 25V P/T electrolytics, 40c ea. Aluminium and plastic instrument boxes and ARLEC multimeters NOW IN STOCK. $1.50 monostable to start timing. Pin 5 goes Spkrs MAGNAVOX 5"x3" 8ohm ea. high allowing pin 9 to go low. As the Belt drive T/T kits 240V AC motor monostable is retriggerable, any contact with speed change. 12" cast alloy bounce only extends the timing period. platter, rubber mat, bearing, spindle and When _the timing period is complete, belt, $25.00 ea. CTS 10" woofers Mod1OW14P 8 ohm pin 5 remains high, due to pin 6 being 50W continuous power, 30-2000Hz. Air held low by the switch. Releasing the suspension foam cone surround, 15oz switch allows pin 5 to go low which ALNICO V magnet. $19.50 ea. 400V, 1.5A, triggers the second monostable. Pin 9 Silicon bridge rectifiers' 85c ea. now goes high and remains high after Balance meters 35Mm x 15Mm, $2.00 ea. the timing period as pin 8 is being held A&R 240V ac primary, 115V secondary low. Any bounces during this period at 95Vamps, $7.50 ea. monostable. Phone enquiries and personal shopping Contact Debounce merely retriggers the first For this reason, to ensure correct only. Also in stock - large range of electro- The circuit described below can be used operation, the period of the second lytic capacitors - wire wound resistors to provide contact debounce, or can be monostable must be twice that of the - switches - panel meters - transistors diodes plugs sockets edge used as a dual retriggerable monostable. first. - - - - The period of the bounce supp- connectors - vero board - transformers With SW1 in the off position, pin 5 We could go on and on, so period - chokes. is low, and holds pin 9 high - the ression is the timing of the first call in and browse around and check our same as the input. When the switch monostable, and is given by: low, low prices. closes, pin 6 goes low causing the T (seconds) = 0.693 x R x C.

ELECTRONICS TODAY INTERNATIONAL - MARCH 1978 111 SOME OF ELECTROCAPS T03 MOUNTING KITS: 10 for $1 or $4 (UPRIGHT) box of 50. Generous kit includes mica, screws, nuts, washers, tag, nylon brushes. POLYESTER (per 100 prices in brackets) LEDS: AUSTRALIA'S FILM CAPS $12 per 100, $110 per 1000, or Cap. 16V 25V 50V 17c each, 10 for $1.50 clips 3c each all LOWEST E12 10% 100V 0.47 uF quantities. LEDS superb - 5mm red - All values .001 to .01 - 7c ea. thru to all all all well diffused. Wide viewing angle sample .01 - 7c .1 - 13c 10 uF 5c($3) 6c $39..) 70 54 40c stamp. - COMPONENT .012 - 8c.12 - 14c 22 uF 6c $35. 7c $4 ec $5 .015 - 8c.15 - 14c 33 uF 8c($4 9$ $53 loe $6 .018 - 8c .18 - 14c a7 uF 9c($5) 10$ $6) 1]e $7 Potentiometers: 50c ea. rotary carbon sing. PRICES 022 - 8c .22 - 16c 100 uF lOc $6 12c $7 14c 511 gang ) log or lin: 1K, 5K, 10K, 25K, 50K, .027 8c .27 16c $17 - - 470 uF 16c(512) 100K, 25K, 500K, 1M, 2M (metal shafts) .033 - 8c .33 - 18c 22$ $16 45c $30 Trim Pots: 17e ea. lomm 1W horiz. or .039 - 9c .39 - 19c 1000 uF 22c($18) 30$ $25 75c $50 - .047 9c .47 22c 1000 uF/16V axial - 20c ea. $8 per 50 vert: 100 Ohm to 2M NOTE: REGULAR PRICES - 2200 uF/50V axial - 95c ea. $8 per 10 - .056 - 9c All Full axial list NOT TEMPORARY .068 - 10c values price - SAE ZENER DIODES: 15c each 400mW 5% SPECIALS - KEEP US IN .082 - 10c In uF E24 values 3V to 33V MIND FOR THAT 10% Off 100 same uF NEXT ORDER 2c RESISTORS - our 2 year old Keep electronics a hobby and not a luxury, price still current. Opposition compare our prices and buy from us. hoped we would go broke but our Same day turnaround service (unless price remains at 2e ea. swamped). All goods top quality and new. 1 Ohm to 10 M i/aW 5% E12 carb. No minimum order. One P/P charge of film $1.80 per 100 same value (or 40c regardless' of quantity. Advert current 1/2W 3c, $2.50 per 100 same value) 3 months for late readers. 5C Rs: TRIACS: DIODES: 0.8A 30V C103V - 35 2A 400V ESP240 - 65 1N4001 - 7c(1A 50V O.8A 200V C103B - 60 6A 400V SC1410 - $1.30 1N4002 - 8c((lA 100V 4A 30V C106V1 - 40 l0A 400V SC146D - $1.50 1N4004 9c(lA 400V 4A 400V C106D1 - 75 25A 400V SC2600 $2.50 1N4007 12c(lA 1000V LECTRONI 8A 500V C122D - 51.05 [MAC S12 - 35 1N4148 6c $4.50/10 P.O. BOX 33, CORAMBA NSW. 2466. 8A 500V C122E - $1.20 Chart to Identify leads $38/000 26A 400V C37D - $2.50 Plus trigger Info. 15

7 DIGIT FREQUENCY METER KIT

'Electronics Australia' March 1977 design High Stability Crystal (30 P.P.M. -100C to +600C) in cold -welded HC18/U holder. ALL high quality components (National, Fairchild, etc.) Fibreglass P.C. Boards with component overlay 'Polaroid' front panel, L.E.D. readouts, 'BNC' socket standard - 'UHF' socket optional. Pre -drilled aluminium chassis with Mack 'Marviplate' cover. 240 volt operation - provision for 12 Volt operation. Instructions in- a cluded.. Postage N.S.W. $2. Interstate $4. Registration $2, "Comet" -Sydney $2 insured. 'T.N.T.' Air-road courier, insured $6 anywhere in Australia. Separate components (post free) Crystal $8, 95H90 prescaler $9.50.

Please Note: The prices shown in December ETI were a misprint. COMPLETE ASSEMBLED20 ÓMMHz $82!00 MHz $122 00S J.R. COMPONENTS 200 MHz $89.50 200 IdIHz $129.50 P.O. Box 128, Eastwood, N.S.W. 2122 Ph: (02) 853976. TRANSFORMERS 12 or 24 Volt Primaries Range: 220-240 volts Ref. Amps Wt.Gms. Secondary Taps S Miniature transformers with screens: Primaries 220-240 volts Ref. Amps Wt. Secondary S 112 0.5 623 0-12-15-20-24.30 5.00 Ref. MA Wt. Gms Volts S No. 12v 24v Gms. Windings 79 1 737 0.12-15-20-24.30 6.25 238 200 85 3.03 2.50 242 300MA 150MA 198 0-12V at 150 MA o 2 2.50 3 2 1361 0-12-15.20-24.30 8.50 212 .1A lA 595 0.6 0.6 5.50 111 0.5 0.25 283 0-12V at 0.25A x 2 3.25 21 4 2600 0-12-15.20-24.30 10.50 13 100 113 9.0.8 2.50 213 1.0 0.5 425 0.12V at 0.5A o 2 4.00 89 10 5670 0-12-15.20-24-30 21.75 236 330, 330 198 0.9,0-8 2.50 71 2 1 793 0-12VatlAx2 6.00 50 Volt Range: Primaries 220-240 volts ' 207 500,500 566 0.8-9.0-8.9 5.25 4 18 2 1020 0.12Vat2Ax2 7.50 Voltage obtainable: 6, 7, 8, 10, 14, 15, 17, 19, 21, 25, 31, 33, 40, 205 500, 600 1077 015-20, 015-20 6.00 70 6 3 1538 0.12V at 3A o 2 9.50 50, or 25-0-25 214 300,300 623 020,0-20 4.00 108 8 4 2268 0-12V at 4A x 2 12.50 Ref. Amps Wt. Secondary Taps S 221 700 (DC) 737 20.12-0012.20 6.50 116 12 6 2722 0-12Vat6Ax2 14.00 102 0.5 137 0.19.25.33.40.50 V 7.00 206 IA IA 1304 0-15-27,0-15-27 9.00 115 20 10 5300 0-12V a1 10A x 2 20.75 103 4 1304 0-19.25.33-40-50 V 8.00 203 500,500 822 015.27.0-15-27 8.50 104 2 2495 019.25.33.40-50 V 10.50 204 lA 1A 1417 0-15.27, 0-15.27 12.00 15/30 Volt Range: Primary 220-240 volts: Secondary 105 3 3176 0.19.2533-40-50 V 12.50 106 4 4100 Windings 0-12-15v at 5 amps, 0.5-9.15v at 5 amps. Voltages 0.19-25-33-40-50 V 15.00 107 6 obtainable: 3, 4, 5, 6, 8, 9, 10, 12, 15, 18, 20, 24; 30, or 12.0-12 5444 0.19.25.33-40-50 V 22.00 60 Volt Primaries or 15.0-15. Range: 220240 volts - All transformers continuously rated Voltages obtainable: 6, 8, 10, 12, 16, 18, 20, 24.30,36.40,48,60 vacuum varnish impregnated, and Ref. Amps Wt. Secondary Taps S or 24-0-24 or 30-0-30. guaranteed. Ref. No. 15v 30v gins. Amps Wt. Secondary Taps S Prices do not include postage or packing. 51 10 5 3120 0-12.15, 0-5-9.15 15.00 124 0.5 737 0.24-30-40-48.60 V 6.50 Assess postage to your address using 126 1 1361 0-24.30.40-48.60 V 8.00 your weights given and add 10% of post- 30 Volt Range: Primaries 220-240 volts age 127 2 2495 0-24.30.40-48-60 V 10.50 rate for packing. Unless quoting sales Voltages obtainable 3, 4, 5, 8, 10, 12, 15, 18, 20, 30, or tax number add :15% 6, 9, 24, 125 3 4083 0-24-30-40-48 60 V 15.50 to order cost. or 12-0-12 15015. 40 5 5670 0.24.30-40-48.60 V 21.00 DOUGLAS TRANSFORMERS, DEPT. MO, BOX 23, COORANBONG, N.S.W. 2265.

112 ELECTRONICS TODAY INTERNATIONAL - MARCH 1978 INTERNATIONAL ELECTRONICS UNLIMITED DISCOUNT ON ALL LINEAR 0038 FUNCTION GENERATOR LED DISPLAYS SPECIAL Voltage conlrolléd on Maio* - sine. PN03S9 RE0 CC .775" RHO 5 .59 IC'S AND LED'S SPECIALS equate. biangular output. $3.95 160500 RED CC .50" RHO .79 f .49 140507 RED CA .S0" x140 .79 OFF ON $25.00 LM300 TO -5 DL 104 RED CA .27" (ND .99 10% SALE LM302 TO -5 .39 MM 5330 OLIO RED CC .30" LOD .99 1.1.1307 mDIP .19 D1707 RED CA .30" 9110 .99 15,10 OFF ON $50.00 457 DIGIT DVM LOGIC $ : 4.95 D1747 REO CA .40' LOD 1.49 TTL LM308 TO -5 .59 MANS GREEN CA .27" LOD .69 .TTL LM311 T0-5 .49 MAN I YELLOW CA 27" LNG 69 BARGAINS LM311 mDIP .49 SIGNAL DIODES- 400PAW MANS/ YELLOW CA .30" LOD .99 7400 .11 7451 .20 74155 .75 .79 54466610 ORANGE DOUBLE DIG 7416 f .19 340T -5V CA SR" RHD 99 7453 .20 74156 .75 7401 .18 7430 .16 340T -6V .79 201$1.00 MAN6670 ORANGE 07 DIG .20 74157 ROD 7402 .14 7454 .85 7432 .19 340T -15V .79 CA .54" 91 74158 1114146740 RED DOUBLE DIG. 7403 .14 7460 .20 1.39 7437 .19 LM380-8 mDIP .69 7464 .35 74160 CALCULATOR CC .56" RHO 99 7404 .16 1.23 7438 .19 LM565 DIP .89 9 MAN 3N MANHOSO REO DOUBLE DIG 74161 7405 .19 7485 .35 .95 7440 .13 LM723 DIP .39 DISPLAY CC .56" 9110 99 74162 ON PC BOARD MAN4630 RED CA 110' RHO .69 7406 .29 7470 .38 1.39 7445 .49 LM739 DIP .79 74183 NSN74R" RED CC 30" ROD .99 7407 .28 7472 .35 .95 7495 .55 $ .75 .22 7473 .35 74164 .95 ... 7408 74123 .25 1 11.1 1111.511'1. CALCULATOR KIT 7409 .17 7474 .31 74165 .95 74141 .59 w I!H 544.541íR5 LITRONICX 1502 MEMORY 74168 5738 7410 .16 7475 .49 1.19 751.580 .99 ...a Jumbo LED'S 7411 .25 7476 .34 74170 1.90 7413 .43 7483 .68 74173 1.49 SHIFT green - yellow 7414 .65 7485 .88 74174 1.19 MARK I CLOCK KIT amber - clear 16C ea. 74175 1 DIGIT CLOCK KIT WI711 ONE PC REGISTER 7415 .25 7486 .38 .95 13MS314 74176 BOARD. ACCOMMODATES 7416 .35 7489 2.25 .84 CLOCK CHIP AND 6 114D359 2510 51.75 ZENER 400MW 7417 .35 7490 .43 74177 .84 DISPLAYS. CONTAINS ALL DIODE - 3 SWITCHES AND 7491 .75 74180 .95 COMPONENTS, 2511 1.95 3.6V 5.1V 6.8V 15V . 7420 .18 ASSEMBLY INSTRUCTIONS. HAS 7423 .37 7492 .48 74181 2.30 TERMINALS 105 ADDITIONAL 2518 2.50 4.7V 5.5V 10V $ ,1 .35 7493 .48 74182 .85 REMOTE DISPLAY. 5 EA. 7425 510.95 2522 1.95 7428 .22 7494 .75 74185 2.20 81$1.00 ANY MIX RESISTOR PACKAGE 7427 .35 7495 .75 74190 1.25 2532 2.29 CARBON FILM 25% 111 OR VI W 7430 .20 7496 .75 74191 1.15 CERAMIC DISC J 5016 89 7432 .23 74100 1.15 74192 .89 USAGE EVALUATED ASSORTMENT 74107 .37 74193 .85 7437 .25 CAPACITOR PACKAGE RESISTOR PACKAGE 455 RESISTORS, 44 VALUES 7438 .25 74121 .37 74194 1.15 EA. FOLLOWING VALUES 50 VOLT CARBON FILM ± 5% 111 or 05W 7439 .50 74122 .38 74195 .74 10 OF - $12.95 7440 .15 74123 .45 74196 .98 191 33pí 82p1 220p1 820p1 .022u5 15 EA. OF THE FOLLOWING VALUES 7441 .85 74125 .54 74197 .95 5p1 47p1 10091 270p1 .001u1 .030u1 100, 220, 470, 1K, 1.5K, 3.3K, KEYBOARD 7442 .59 74128 .58 74198 1.69 1Op1 56pí 150p1 470p1 .0047u0 .050uí 4.7K, 6.8K, 10K, 33K, 100K, 1M 20 KEYS 7443 .65 74132 .75 74199 1.69 22p1 88p1 180p1 800p1 .01uí .1u1 1 SLIDE SW 7444 .73 74141 .85 745200 3.95 180 RESISTORS S CAPACITORS ' $10.95 $5,45 .99 7445 .65 74145 .90 74279 ,79 24u 7446 .81 74150 .98 7447 .59 74151 .68 2708 6 DIGIT 74153 .80 5314 ELECTRONIC DOOR CHIME KIT DISCRETE LEDS 7448 .79 MULL SPEED EROM ME4101rared CI.., 17" dig. 1.29 7450 .17 74154 1.20 CLOCK CHIP MYIOB Clew TOSS 17' dig. .15 $10.95 WITH TI TMS 1000 *4050 CI., 41101 09" dog. .12 LOW POWER SCHOTTK Y $2.95 MICROPROCESSOR CHIP 351100 Red point 19" dig .12 111309 Red dill. 12" dig .12 741500 .39 741532 .14 2.04 741595 1702A 74S200 PROGRAMMED TO PLAY RIT-71.03 White 013t no í1.nge 124" dig. .15 741102 .36 74E540 .45 7415107 .59 RIC200 9.4 0111 10" dig. 24 DIFFERENT TUNES 741104 .36 741542 1.40 7415154 2.20 256 BIT RAM Cun.n17.g .25 S3.95 x14403 Red 0111. .19" die. .15 74(101 .38 741574 .59 741519) 2.20 TRI-STATE: 3377150 Gr... yeller .tuber 741.510 .36 741.590 1.30 7415197 2.20 8008 w clew ddL .19" du. .16 74(570 .36 741593 1.30 SOSOA . $3.25 $11.95 DART M CAPACITORS Low POWER Solid dipped +20% 74(00 .29 74151 .29 74190 1.40 Al 5100A LD110, LDI11 10 mid 169 S .40 74102 .29 74155 .29 74191 1.20 .1 mid 359 S .25 3., 011.11 4 NI IINSRIIR 10 mid 259 .45 74101 .23 74(71 .29 7414) 1.50 $6.95 .33 odd 359 .25 IS mid 10V .40 741.04 .r 74172 .45 74195 1.50 $24.75 I lnld 359 .25 206 .25 IS mid 209 .41 74106 .M 74172 .5k 74196 2.25 2513 2.2 mid .30 22 mid 168 .4S 74110 .29 74(74 .56 741154 2.25 82S23 CHARACTER GEN $39.50 hHl1H1.SI.w L2 mid 359 256 BIT PROM 5.3 mid .N 35 mid 109 .40 74120 .29 74171 .75 741145 2.16 645855 ASCII 359 .70 47 mid 6V .40 74130 .T 74(05 1.09 LINEAR CIRCUITS 4.7 mid 169 $2.95 $6.95 .70 mid 411 .45 74242 1.34 74(14 .43 143001,. I77 114537251 103 147330 70 6.1 mid 69 54 LM301CH 29 4.437601. 5e 147396 99 6.5 mid 505 .40 ISO mid ISV 1.50 HIGH SPEED Clock Kit 1*03020 .5 11.36014 1 /9 11474101461 32 LM30411 00 113340 1301. es LM70CW1.1 32 74H00 74H23 74H0I MM5369 Divider mOIP 2.49 .25 MM5314 with 6 61571 .27" displays 2 P.C. 1.11307C5 20 1513411. 175 1.2/1741C0 35 74H01 741110 741142 Crystal 3.58 MHZ color TV 1.74 .23 boards Display board may be remote. 1430711 30 13.3025 t 75 047474 79 1.95 74H04 71140 74H74 - Crystal 3.010 MHZ .25 Internal or wall Iranslormer can be used. 1.1113010. 00 143050 45 11.747111 74H04 .23 74650 7411101 1M3040 I 05 14E5310 2 90 1M740CN 35 all necessary 99 NE 5.01. 2 60 70110 .21 74152 74H102 50-60 Hz, 12-24 hour. Includes 111/3040 2 90 1511)100 CARBON FILM RESISTORS 50'. 144370(3 I 07 711544. I 09 0a1.14,1 7 50 74H 11 .23 74H53 701102 transistors, resistors, capacitors, diodes, 3 IMIBO 19231101. 19 045501 75 411450C1. t 29 - AU 614SO4R115A11.1E5 741420 74H55 74H 106 .25 switches and complete assembly instruc- 003110 Be 0/1155C1. 39 L51145005 59 'S OHMS TO 5.014 1111 MN 74H21 70460 14H101 .25 tions. 1143113 89 1115544 115 1541.961d 09 - 41 I. SI4'D*R0 1411'1, /x051 1193,93 113 LM560H 05 1911 9000 2.. CMOS CK6-3 1151114 TO ISM 01145 $12.95, 1043200 1M5011. 05 1.11112209 Be Q11. red* ren(f 40004 4011A 1.19 .26 40664 .69 5 B 2 12 14 1 29 1145956 19 15141309 Bº ," 10 CALCULATOR CHIPS i. ., , imin,m 40014 .25 46204 1.72 4041* .44 1443101 1145964 39 003048 1 19 CT5002 12 digit. 4 'unction il.ed decimal 4002* 40214 .44 5 12 15 1 19 1143600 39 1 49 .35 1.10 40694 battery operation .0 in 1.95 CA30.1 10 6107, - 143223 1 59 59605 t0 4004A 1.35 40224 .14 4071A .26 plus memory, bed 15.34006 10100 110 r. 105.4 CTS005 12 digit. 4 lunctlon 324N33511701. 29 1M7524 40074 .M 40234 .25 40724 .25 1.5.324N41.5.324N 6011100 5.04 r4 decimal -70 pin L49 1192290201 152 1925010 49 IM75I5 79 4004* 1.52 4024A .09 407)4 .29 444457I5 0 digit. 4 ¡unction. floating decimal 144)3908 I SS 1427030 59 003.6 4 59 40094 40254 1%D .57 .25 40754 .39 Is pin 1.90 WJ.Ox 142703CN 39 7S.5ICH 35 METAL FILM RESISTORS 4010A .54 402.7A .59 40744 .39 5 4 6 12 427096 25 75452(3 35 444457).6 digit. 4 Iunc lion, 9V ballery STANDARD DECADE VALUES FROM 401 IA .29 4021* .96 40424 .35 15 10 24 1 29 04704,. 29 7545305 35 operation - IS pin 2.95 401211 .25 40301 .44 /511* 1.56 1M3é0T 1.13/10.459 75454CN 15 10.5 OHM TO 4644( OHM S pew memory and MMS72S 1 digit. Iuncllon 5 0 12 1337115 39 75,915 I 4013* .45 40354 1.27 45144 1.56 1 A(H MINIMUM 10 MINIMUM 109 constant 1í911+n0 decimal, 99 banery ! t0 24 1472)0 65 7549278 05 40144 1.27 40404 1.19 45454 2.10 era 54(U) PIE VAIUI operation - 74 pin 3.95 Ir0--E9v.I I le 11472338 57 40154 1.27 40424 1.47 9 digit, 4 function, 99 balery 0 10 1.10 94945729 .0320 1 15 U12507 1 es 184212 1 75 40164 .44 40491 .59 3.95 opn.lion - 27 pin .82206 2 91 19.136 1 75 .34739 115 10 . 100 .20 5.15 40174 1.01 40504 .59 102207 2 95 m.202 1 75 100 .10 5.09 74C 00 .11 74(74 1.04 74(162 7.49 OPTO ISOLATORS UNIVERSALaREADROARD 74( 02 74(74 74( 761 256 .34 1.34 14C132 Opto 601.107 diode 1.09 -7 74(04 74( 184 2.66 I-1 1 5-1 1 r. .. "I 3' .44 74(107 1.13 94(72 Opto 6dwor tunostot 1.09 li A..M.1.. MP 11'. let 74(31 .(i 74(151 2.62 74(171 2.72 .p... . .4.ap...6... lee 74(10 .35 74(154 74(185 7.24 3.15 1e 1'I., nd.mpl. 1,0431 74( TO .75 74(157 1.74 00(95 1.15 MINIATURE SOLID STATE b....d.n4 It ... u.10 11.50... ' 74(42 131 74(164 144 KO( 97 .% IC 119144004R0119144004R01 ELECTRONIC BUZZER 5 p,n IC. ..rA .31414.001 74(7) 1.N 74(161 7.49 ..n.nod.H. Dale sheets on request. Add 306 each p . I. r. LONG LIFE HIGH R:LIABILITY e t tw.. hoe. 1/141. A.,. d. ..14 CERAMIC - p4ud.0H,teepee ceo ere. 2 5014" . 130" 01.40 w. II item is priced below $1.00 each. DISC LOW CURRENT DRAIN CAPACITORS NO MOVING CONTACTS SaIislaclion guaranteed. Shipment will be made within 3 days Irons receipt of Ipl 500 56p1 SOY 2701.1 500 0111' 100114 NO ARCING NO RF NOISE order. 5pl 500 ISM 50V 3905,1 500 022,,1 100 - 714 5011 12p1 500 4711p1 -014 0301,1 SO0 RICH & CLEAR SOUND Prices are in Australian 5. Payment may be made with personal check. lOpl 500 130111 SOY 6110p1 500 05091 400 (include receipt). card (include no. a, 78 dB min Al 111. - 450 Hz IA internalional money order charge 2251 500 120p1 7800 82014 505' bol 50 expiration dale) or bank cheque made payable in U.S.S 2751 5014 1501.1 5110 COW SOY 18-106 6V 1SmA 4-9 VDC 55.99 501( items are shipped via air -prepaid unless otherwise indicated. 31p1 16014 500 0047o1 505 16-112 12V 15,oA 9-20 VDC 1.99 All 4714 50Y 2201,1 500 014f 500 IC SOCKETS Add 51.00 lerriEe charge lo, orders less than 510.00 (each) (Minimum 10 Solder Tall - low profile 74 pin per value) 1 pin 5 .17 .42 INTERNATIONAL ELECTRONICS UNLIMITED 14 pm .20 D Pm .59 VILLAGE SQUARE, P.O. BOX 449 CARMEL VALLEY, CA 93924 USA 0-100 5.10 ea S.05 ea 16 40 P'n pm .22 .69 TELEPHONE 406659-3171 100- 5.04 ea 14 pn .29 SERVICES electronics today ADVERTISERS INDEX

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114 The competition don't like the sound of this at all.

For quite some time, other manufacturers have UD-XL II TAPE, FORTHE CHROME POSITION (70us) been trying to produce tape with the qualities of UD-XL II tape is such a dramatic improvement the Maxell UD-XL. At the same time, Maxell have on most other tape that can be used in this been quietly perfecting an even better series. position, that comparison is really unfair. The UD-XL I and UD-XL II tapes are designed For example, if you're familiar with conven- to attain maximum performance at the ferric and tional chromium -dioxide tape, you'll know of the chrome position on your tape deck. Whichever associated problems of head wear, poor output tape position you choose, Maxell can give you a uniformity and relatively high price - plus low better performance. maximum output level and rather high distortion. UD-XLITAPE, FORFERRIC(norm.) POSITION(120us) UD-XL II tape offers you excellent MOL, UD-XL I offers an excellent sensitivity of 1 dB sensitivity, and an output improvement of more higher than even UD-XL. MOL performance is also than 2 dB over the entire frequency range. 1 dB higher over the entire audio frequency Maxell's unique 'Epitaxial' process gives you spectrum. The result is a new standard in ferric absolute sensitivity and stability, and no drop -out tape, with wider dynamic range and less distortion problems. What's more, the shells are moulded in than ever before. diamond cut dies, and made to tolerances 5 times

How does the UD-XL I compare then, with greater than the Philips standard. And, like all ordinary low -noise tapes? Maxell tapes, UD-XL II has the unique 5 -second Sensitivity is higher by 2.5dB, and MOL cleaning leader. performance by as much as 6dB. In short, if you're recording in the chrome Yet, for all this UD-XL I requires no special bias position, you can now achieve all the advantages - or equalization. Simply set your tape selector as with none of the drawbacks. you normally would at the ferric position - but A prospect we think you'll find very exciting - there the comparison ends. even_if the competition don't. maX thtPq 011

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W13/79 For details on all Maxell Recording Tape write to Maxell Advisory Service, P.O. Box 49, Kensington, N.S.W. 2033 Whth the real advanoqe oF owning makhina heno comoonenLr? Matched stereo components are not simply com- The Musical Truth is something special in sound. It's ponents that are designed to look alike. Instead they an indication thát your records sound as good in your are matched to ,deliver the right kind of balanced listening room as they did when they were cut in the performance that will bring out their very best studio, or your tapes just as good as the original musicality under all conditions of use. The real sound or music you recorded. Only superior advantage of owning matched stereo components is components ... matched to handle the fine nuances the way they work together in the areas of critical of music can create pure Hi -Fi entertainment for your performance, such as input/output power levels, enjoyment. That's why if you're serious about music, distortion and signal to noise ratio. The way they you'll want matched components ... just like these deliver what we at JVC like to call The Musical Truth. JVC units we've pictured here.

The JL-A40 direct - selling JVC knobless receiver line. drive turntable is You can stack it with the receiver, a beauty in its co-ordinate the design of your own way, what system, operate everything from the front. It features a wide 30- with automatic. The JR-S300 II FM/AM stereo re- operation for 16,000Hz (chrome, typical) fre- ceiver gives you dependable power arm cut/shut-off, a quency response and a high output (50W RMS per channel, beautifully realisticprice, low0.03% 56 dB S/N ratio. THD 0.1%), advanced tuner wow/flutter & high 70dB S/N ratio. circuitry (usable sensitivity 10.8dBf) The KD-S200 II stereo cassette and the unique JVC five tone - tape deck matches the best - zone S.E.A. Graphic Equalizer. JVC Hi -Fi Components beautifully matched for your entertainment!

Balanced erformónce! KD-S200 MARK II - - .f ;22= /-- j v oc

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o T.y,LFFFIFF.- .JL.A40 « r Í.o1.. Ít:='1. '. ' ' ' - mwolo.l _g . 0. .r I , Wp. tienulrJ;..- JVC J1/c fi / pure Ni F enrerlainmenri JVC For details on all JVC Hi -Fi Equipment, write toT717C-grivisory Service, P.O. Box 49, Kensington, N.S.W. 2033 the right choice

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