December 1987 British Aerospace: 10 Years in Space Numbers and the Machine 1987 Cumulative Index Readers' Survey UK £1.50 IR £2.20 (Incl

December 1987 British Aerospace: 10 years in space Numbers and the machine 1987 cumulative index Readers' survey UK £1.50 IR £2.20 (incl. VAT) NOW Alt PRINTERS BBC Micro Computer System EPSON KF915 156 toll 1369 fal LX800 E180 la)BROTHER HR20 BBC MASTER SERIES: WORD PROCESSOR ROMs: E349 FX800 E299 la)STAR NL10 (Parallel Mace)._ E190 fa) AH315 BBC MASTER 128K _ . £346 a: VIEW 2.1 . £35 (dl VIEW 3.0 £48 lc) FX1000 E405 la)STAR t.L10 (Serial Interface)- £219 fa) ADC06 Turbo I65C1021 Card £99 (dl Spearnaster E49 (d) VIEW INDEX 112 (di ADCO8 512 Processor £189 Ib) WORDWISE E24 WORDWISE - E38 (dl EX800 E409 la)JUKI 6100 (Daisy Wheel) .... E295 (al ADF14 Rom Cartridge ...E12.75 SPELLCHECK ill EX1000 £549 la)INTEGREX (Colour) £549 (a) ADF10 Econet Card £41 (dl WYSIWIG .£21 (dl E31 (dl L0800 (80 col) E399 la)NAT PANASONIC KX P 1081. E149 fa) ADJ22Ref. Manual I E14 (c) INTERWORD £46 EDWORD I) E43 la) Li31000 (136 coil E529 fa)NAT PANASONIC KX P 3131. E249 (a) ADJ23Ref. Manual Part II.. £14 (c) TAXAN KP815 180 coil E269 (a) ADJ24 Ad: Ref Manual £18 Id LANGUAGE ROMS: (Ye hold in stock a 1.3.7e variety. of ar..27ter artad-drents, interfaces and consurnabfes Micro Prolog E62 (c) Microtext £52 (Cl Please mite or phone for 'loafs BBC ARCHIMEDES ISO PASCAL £51 LOGOTRON E55 Please empire thorn avadabilty and LOGO....£46 (c) MACROM £33 (dl dermas of the - em. Use £39 (d) COMAL _ _ _ _ £43 (di ACCESSORIES Oxford Pascal E36 BUFFALO 3211 Buffer for Epson printers £75 (di: FX 60 plus sheet feeder E129 (bi: UPGRADE KITS: EPSON Serial Interface: 8143 E30 lb); 8148 with 2K buffer E65 ibl. 1.2 OS ROM El5 COMMUNICATIONS ROMS: DNFS ROM £17.50 (dl EPSON Paper Roll Holder E17 lb): FX80.,80 +185 Tractor Attach E37 to): RXFX80 TERMULATOR E25 (di Dust Cover £4.50 (dl; LX80 Tractor Unit E20 lc); 10800 Tractor Feed £47 lb). BASIC 11 ROM (BBC E22.50 MASTER TERMULATOR £34.75 (dl ADFS ROM £26 Id) COMMUNICATOR £49 (dl EPSON Ribbons: MX/RX(FX130 E5: MX/RVFX100 £10 (dl: LX80 £4.50 (dl: 1770 UPS Kit £43.50 (dl COMMSTAR II £28 (dl JUKE: Serial Interface E65 (d): Tractor Attach_ £149 fa): Sheet Feeder E219 la): Econet Kit (Ems-) E55 MODEM MASTER E11 (dl Ribbon E2.50 (a): Spare Daisy Wheel £14 Id). ACORN ADD-ON PRODUCTS: COMMAND £34 'BROTHER HR20: Sheet Feed £229: Ribbons Carbon or tiyfon £3: Tractor Feed Torch ZEP 100 £229 (al UTILITY ROMs: E116 lel; 2000 Sheets Fanic4d with expo fine pert. 9.5- - 113.50: 15- £17.50 to'. 512 2nd Processor E195 lb) DOTPFIINT PLUS for FXRX compatibles BBC Parallel Lead E6: Serial Lead E6 IBM Para e! Lead i2rn C12 IEEE Interface £265 (b) DOTPRIiJT DUAL for MX range Teletext Adapter E95ml Acorn Graphics Extension Rom _ £28 Id/ Acorn 65CO2 Turbo £99 tb) MONITORS Merlin with 57 disc utilty commands MICROVITEC 14" RGB TAXAN K12SV620 12" £279 iai 100 page manual £37.50 (c) Ask for full details on our full range of software 1431 Standard Resolution .. - £179 (a)TAXAN K12SV625 12" . _ £329 (a) 1451 Medium Resolution £225 (a) 12" MONOCHROME MONITORS: 1441 (di Res £365 (a)TAXAN: MULTIFORM Z80 2nd Processor for the BBC MICROVITEC 14" RGBiPAL & AudioTaxan KX 117 12" Green P3) E 85 lai This unique 280 2nd Processor running OSiM will a9ow use of almost any standard CP/M soft- 1431 AP Standard Resolution E199 (a)Taxan KX 118 12" Green P39 95 iai ware on the BBC micro. It is supplied with a number of different CPJM formats and includes a 1451 AP Me:Wm Resolution .£259 fa)Taxan KX 119 12" Amber E 95 ra, utility to configure it to read other formats. This is particularly useful in environments where com- PHILIPS: MICROVITEC 20- RGI3iPAUAudE3o80 E 75 f a t puters with different CP17.1 formats are used and the data cannot be easily exchanged between 7502 Green Screen 2030 CS std Res 7522 Amber Screen E 79 !a, them. Mains powered (includes Pocket Wordstar & MS/DOS RAWutrity) £249 2040 CS 141 Res £685 (a) MS DOS Read Write Utifity E49 lc) 7542 White Screen E 79 lei Mitsubishi 14" ROB Med Res. (812C1.119 8M)(a)All Phelps Monitors supplied with swivel META Version 3 ASSEMBLER stand Assembles 17 of the popular processors. Over 70K long program on two roue ant provides complete Editing and Assembly facilities. It uses appropriate mriemorecs z processors. Fully nestable macros, nestable conditional assembly OF/ELSE/END; -- - No VAT on books; Carriage (c) source code, true local and global labels. 32 bit labels and arithmetic. 30 ways to s, _ code and 50 directives. View 3.0 User Guide £9.00 A powerful editor with many features. Send for detailed leaflet. £145 LANGUAGES: Viewstore £9.00 6502 ASS, Lang Prog E19.95Viewsheet E9.00 BBC DISC DRIVES 8086 Book £23.95'Nordwise Plus E9.95 5.25" Single Drive: Acorn BCPL User Guide E15.00 Acorn FORTH E7.50SOUND & GRAPHICS: 1 x 400K 40.801 DS: TS400 E99 (b)PS400 with psu £109 It) Acorn LISP Mastering Music £6.95 5.25" Dual Drive: Atom ISO Pascal Ref Manual .. £10.00 2 x 400K 40.80T DS: TD800 ... 1179 la)P0800 with psu £199 ial intro to COMAL £10.00DISC DRIVE SYSTEMS: 2 x 400K 401101 DS with psu and built in monitor stand POBOOP E209 Advanced Disc User Guide E14.95 3.5- Drives: intro to LOGO E7.50 Micro Prolog Ref Manual E10.00Disc Book £3.50 1 x 400K SOT DS TS35 1 £75 lb)PS35 1 with psu £99 Introduction to Turbo Pascal.. 114.95Disc Prooramning Techniques £7.95 1 400K 80T DS with psu TD35 2 E129 fib)PD35 2 with psu 1169 Ibl Prog the Micro with Pascal 18.50Disc Systems £6.95 The UNIX Book E7.50File Handing on the BBC £6.95 3M FLOPPY DISCS Unix User Guide E19.95APPUCATIONS: Industry standard floppy discs with a life time guarantee. Discs in packs of 10: Understanding Unix E18.45interfacing Proj for BBC £6.95 51/4 DISCS 3% DISCS BBC MICRO GUIDE BOOKS BBC and Small Business E5.75 BBC User Guide Acorn £15.00 40T SS DD £8.50 (d)40T DS DD £10.50 Id)80T SS DD £15.00 (d) PROFESSIONAL SOFTWARE BBC Plus User Guide Wordstar made easy £16.95 80T SS DDE11.50 Id)80T DS DD .E13.25 (dl80T DS DO £19.50 (d) Drawing your Own BBC Prograrns16.95Introduction to Wordstar£17.95 Inside Information E8.951/ordstar Handbook 111.95 DISC ACCESSORIES Math Prog in BBC Basic E7.95dBase-II for the first time userE16.95 Toolbox 2 E10.95Understanding dBase-Ill 122.95 Single Dec Cabe E6 Id)Dual Disc Cable £8.50 (dl VIA 6522 Bc-o)= 4.50 10 Dec Lt rery Case £1.80 lc)30 Disc Storage Box E6 (ci Multiplan Made Easy E18.95 40 Dec Lockable S.sx E8.50 lc) 100 Disc Lockable Box E13 to) PROGRAMMINQUTIUTY Mu(timate Complete Guide _ £16.95 FlopPciene Drive .at C'ea, -4 Kit...,-;1!-. 20 dsocsat'e crea, 72. ;,:s 5-'," £14.50 o " EIS (di Advanced Sideways Ram Use: ABC of LOTUS 123 117.45 Guide £9.951-2-3 for Business £16.95 Advanced User Guide il3f3C).... £12.50Adv Tech in dBase £22.95 BT APPROVED MODEMS Applied Ass.il.ang on the BBC 19.95Mastering Clai1.1 E 17.95 8BC Micro Sideways ROM's RAM'sE9.95CPIM Bible E16.50 MIRACLE TECHNOLOGY WS Range Guide to the BBC ROM 19.95Introducing CP M SEC & 280 £9.95 MS.PC DOS E10.95 WS4000 V21/23. WS2000 V21,V23 B,g,,,,ers Guile to W.P £7.95 IHayes Compatible,Intelligent. Auto Dial/ Manual Modern E92 Auto Answer) E135 UM WS 2000 Auto Dial Card E27 (di PROGRAMMED ROMS FOR ELEKTOR WS3000 V21/23 Professional WS 2000 Auto Answer E27 PROJECTS As WS4000 and with BELL standards and WS 2000 SKi Kit E5 503-N Jet. Computer Monitor 516 Talking Dice 2716 E 7.30 battery back up for memory .... £244 (b) WS 2000 User Port Lead £5 2708 C 4.80 521 CharGen & Video Routine for DOS WS3000 V22 Professional 504 Disco Eghts 2708E 4.80 Junior 2732 + 2716 £16.40 As WS3000 V21,23 but with 1200 baud full 505 Chess Intelekt. 2 x 2716 E14.60 522 CharGen & video; Routine for ex- duplex E409 la) 506 J C Tape Monitor . 2716 E 7.30tended junior 2732 r 2 x 2716 E24.00 WS3000 V22 bis Professional (Offer &allied to current stocks) 507-N J C Printer Man & PME 523 Char_ Generator 2732 E 9.00 As V22 arid 2400 baud full duPex E537 lei 2716 E 7.30 524 Cluantisizer 2732 E 9.00 WS3000,118C Data Lead £7 id) 508 J C Bus Control 82S23 E 4.80525 Universal Term 2732 E 9.00 510 150 MHz Freq Meter 2.82S23 526 Wind Dir lnd 2716 £ 7.30 E 9.60 527 Elabyrinth 2716 7.30 SPECIAL OFFER PROJECTS: 514 Dark Room Computer 2716 E 7.30 530 Daisywheel trace 2 x 2716 111.00 EPROMs/RAMS Junior Computer Kit £86 lb) Housekeeper kit £58 (b) TECHNOLINE 2764-25 £2.80 (d) ALL PRICES Elekterminal Kit (1980) . £50 (b) VIEWDATA SYSTEM 27128-25 £3.60 (d) ASCII Keyboard kit £75 (b)EXCLUDE VA T. Tel. 01-450 9764 27256 £5.00 (d) J C Books 1. 2, 3, & 4E6.90 (c) eaPlease add carriage 50p unless Using "Prestef type protocols. 27512 £9.90 (d) Universal Terminal (6502) Kit £75 (b) indicated as follows: For information and orders 6264LP-15 £2.60 (d) Elekterminal Kit (1983) £70 lb) evadable 24 hours, 7 days talf8 (1#12.50 (clf1.50) All£1.00 a week. SEE OUR PAGE 5 ADVERTISEMENT FOR COMPONENT PRICES

PLEASE ADD CARRIAGE AS PER CODE & 15% VAT TECHNOMATIC LTD (Export: no VAT, p&p at Cost) MAIL ORDERS TO: 17 BURNLEY ROAD, LONDON NW10 lED Orders from Government Depts. it Colleges etc. welcome. Minimum telephone order 15. SHOPS AT: 17 BURNLEY ROAD, LONDON NW10 Detailed Price list on request. (Tel: 01 208 1177, Telex 922800) 1_11112*Prices subject to change without notice 305 EDGWARE ROAD, LONDON W2, Tel: 01 723 0233

please mention ELEKTOR ELECTRONICS when contacting advertisers December 1987 Volume 13 CONTENTS Number 151

13 Editorial ELECTRONICS In our January 14 Electronics News 17 Telecommunications NewsTECHNOLOGY issue: 19 Computer News 26 British Aerospace: 10 years in space: in the The main theme is 21 Letters first 10 years of its existence, BAe has be- Radio Techniques: come world renowned for its work in space apart from an over- engineering and electronics. view, there will also be some HF/VHF projects. 31 The new AT&T: how is this American giant Other items will coping with its enforced role, and what are include: its aims for the future? The rise and rise 43 Philosophiae Naturalis Principia of the micro Mathematica: it is 300 years ago this year European edu- that Isaac Newton delivered the three cation software books of his "Principia" to Edmund Halley Test & measuring for printing. equipment - 2 BAe: 10 years in space Stereo limiter p. 26 50 Numbers and the machine: the correct use Solar cell ther- of real numbers in computing science re- mometer quires an understanding of the mathematical basis of these numbers. 62 Information theory and Encryption: Brian McArdle explains the areas of overlap and difference between encryption and IT. PROJECTS 22 LCD VU Meter: the combination of a peak detector and a modern LCD results in a LCD VU Meter with a range of 60 dB and a peak -hold function. 46 Multi -function Frequency Meter: a user configurable test instrument for measuring frequency, frequency ratios, time intervals, Front cover 1Z periods, and events. Solartron's Type 1255 Philosophiae Naturalis Principia 56 Digital driver for radio -controlled motors: a HF Frequency Re- Mathematica highly efficient (ii>90%) driver primarily sponse Analyser can p. 43 intended for electromotors in models. be used for electronic, mechanical, 64Application notes: a newly developed inte- and electromechan- grated pulse -width modulator combined ical analysis in with fast switching power FETs allows DC research and pro- motor characteristics to be achieved with duction. Accurate 3 -phase motors. analysis of components operating at READERSHIP SURVEY frequencies up to 41 We ask all our readers to take a few 20 MHz has been Multi -function Frequency Meter minutes to answer the 20 questions in our difficult until now p. 46 first Readership Survey for 3 years. because available instruments could TEST & MEASURING not cope with the INFORMATION high-speed calcula- 38 Events; 38 Cumulative EQUIPMENT tions needed to Index 1987; 45 People; 32 This month we start a regular series of assess the signal 53 New literature; 63 Correc- reviews of test & measuring equipment by magnitudes and tions; 68 & 73 New prod- Julian Nolan. In this issue he reviews the phase shifts. The in- ucts; 70 Readers' services; Hitachi V-212 and the Crotech 3133 dual - strument has many 71 Subscriptions; 72 Terms trace oscilloscopes. Next month, he will applications, includ- of business. deal with the Gould 0S300 and the ing the design and Grundig M020. testing of RF and GUIDE LINES 55 Elektor Electronics Test Equipment: an video amplifiers and 74 Buyers' guide; 75 Switch- overview of the test equipment projects filters, crystal filters, board; 78 Small ads; that have appeared in EE during the past and audio compo- 78 Index of advertisers. few years. nents. EE 4 December 1987

q61)11EL IF' IL E2 TRANSFORMERS FROM AMPLIFIERS FROM 1111 1111111 -ii F55 The UK Distributor for the Standard Toroidal Transformers The UK Distributor for the * 106 types available from stock * Sizes from 15VA to 625VA complete ILP Audio Range \^ * Bipolar Modules - 15 watts to 180 watts STEEL DISHED WASHER * Mosfet Modules - 60 watts to 180 watts * Power Booster -15 watts (for 12v dc supply) OUTER INSULATION * Power Supplies Pre -amplifier and Mixer Modules NEOPRENE SECONDARY WASHERS WINDING * 100 volt Line Transformers

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PRIMARY CORE 200 watt Wideband Bass WINDING END CAPS * Power Slave Amplifiers Write or phone for free Data Pack Write or phone for free Data Pack

Jaytee Electronic Services Jaytee Electronic Services 143 Reculver Road, Beltinge, Herne Bay, Kent CI -6 6PL 143 Reculver Road, Beltinge, Herne Bay, Kent C1-6 6PL Telephone: (0227) 375254 Telephone: (0227) 375254

The Archer Z80 6bC The SDS ARCHER- The Z80 based single board computer chosen by professionals and OEM users. * Top quality board with 4 parallel and 2 serial ports, counter -timers, power -fail interrupt, watchdog timer, EPROM & battery backed RAM. * OPTIONS: on board power supply, smart case. ROMable BASIC. Debug Monitor. wide range of I/O & memory extension cards.

The bowman 68000 65C The SDS BOWMAN-The 68000 based single board computer for advanced high speed applications. * Extended double Eurocard with 2 parallel & 2 serial ports, battery backed CMOS RAM, EPROM, 2 counter - timers. watchdog timer. powerfail interrupt. & an optional zero wait state half megabyte D -RAM. * Extended width versions with on board power supply and case.

6hcrwood l )ata8v5tems Ltd Sherwood House, The Avenue, Farnham Common, Slough SL2 3JX. Tel. 02814-5067 1113EE December 1987

LINEAR ICs CPU cR4S7ALS 1.TERFACES 'CS 74393 1 7415379 130 4536 230 AC7581 1203 LID% 050 709109 510 689036 1200 2016-145 .tao 32.7561 1134 1-00 AD561.1 20 CO 74493 7400 030 1.107415381 4_50 4033 0.75 .40038.5 11.90 1.7379C74 443 TC4910 1.75 6E030 LS 36.00 2101 41:0 1 03 5041 270 9075131 15W 7401 OW 74333 1237415330 003 4saa 00_9075 M3791001 25.00 151733 0.65 7041010 2.25 WS 15021078 5.03 18132 MIN 725 A009 1110 7402 74493 140 7415393 1.00 4541 AN)* 24:0 0.1741 0_22 11341022 450 60C35 21114-35 4.00 2.10 MIN 225 4515510 33 7433 0030 1415548'15 74153364 1.* 4543 a10x) AYI 5:60 1.03 161747 0.70 1041024 1.* 9339 470 2114 1_50 245760 MHz 451 4.51700 07521150 7404 03 7415399 1.40 4551 1 493 2110 4.50 1.51743 033 713411705 3_03 WC39 700 2114-3 2.50 203 51425157518130 741500 190 AY3 &DO 11.11011 1.211 7415 0.33 0247415445 240 450 4 SO 11342002 3% 2147 4.03 251458 250 410261531 141.501 741549. AY36912 553 1511014 1.50 8504 7.50 4702115.532 120 7406 003 034 1.20 45% 0.36 -rowan 7.90105A 3.ao 4110.15 21/0 3.12 MIN 1.75 7407 741502 024 7415467 1.80 .056 0.53 CA33194 1.03 1.411931 1W 1134294 2.40 4116% 1-50 3276 MHz IM 414791000 3,10 741503 741_5540 C43.1284 1.10 850934 sao 7403 .300 024 1W 4557 2.40 191E30 2.50 TD420:6 120 4161-15 O11 aco 357% 10, 110 137002 603 741504 0 24 CAM* 0.70 001871 ECM ate DAC% C81 2V 7410 0.33 7415541 1.03 45% 1.40 1W 1%9675 6120 419-15 150 4.03 4044 1.40 7410 741505 0.24 7.1% 4556 1.40 CA3059 320 1511872 1110 708203) 250 noo 0.33 741560 03 8037 8 1161) 471615 1034-194 404 152 7411 010 7415013 024 741%1 2500 45E6 2_40 CA3103 150 1511836 5_00 TDA31310 7.52 453220 250 4.43 MHz 1.00 0,48131 CA313306 0.70 EC* 17.50 7412 030 741509 0247415612 25.00 4503 1.70 LAM* 4.50 IDA** 350 8741 1200 4125615 3104.603 MHt 250 DFS2C4 350 7413 0.5) 741510 024 1415624 350 0572 0.45 CA30% 0 W t612911 3.013 TEA1000 ZOO 510115501 400 4.9152 MIN 2.1.0 135311 150 741511 CA33896 2.50 1200 7414 0_70 0247415626 22 4%3 0.90 1613332 090 7106100 0.40 87445990 14.50 5514:5114 4.03 5103 MHz 1_53 1158833 1.40 7416 0.36 70512 024 7415E28 4-334 0.48 CA3030411 335LAMM 010 140E2 053 00599361000 5516 4.W5.0% 1.75 O 59331 150 744513 CA3133E 0.90 L743939 1.50 7417 0.40 034 7415693 125 4585 0_60 1 03 11164 090 5'20.8 110 5517 4,03 6.00 604 1.40 13593% 7420 030 741514 0.50 7415E43 203 4724 1_50 CA31331 1.30 18n911 1.81) 11071 0.40 5.338 5356-15 4.00 6.144 MIN1.40 D58833 2.25 7421 0.60 741515 0.24 7415603 1 303 14411 7.50 CA31406 0.46 1.413914 350 11072 0.70 280 611618.3 3.00710 MN: 150 D59336 1.50 CA31401 1.03 2.50 7479 0.36 741520 0.24 7415641 153 14412 7 50 0.13915 3.40 11.074 1.10 SO-Zi 2.90 62641P-15 2607,19 UHT 1.75 O 58338 2-% CA3146 2.25 1.14.3915 7423 0.36 741521 024 74(5642 250 14415 3.03 340 71.081 903 550 6810 2.03 8 03 1.1110 1.50 MC14113 003 7425 0-40 741.521 024 7415647 1 303 14419 283 CA3196 1.50 L7013600 1S0 1190 0_55 745193 1.93 8_8E7 MIN 1.75 MC10% 003 CA31616 2930 7.50 7426 0.40 741524 0_50 7415643 293 14490 420 ZOO 50515131 Z30 11033 0_75 /1196 793 745201 3.50 10.00 511-10 1.75 1.11:2446 2_50 CA31626 600 MC3459 4.53 7427 0-32 741526 024 74155131 303 144E6 4.50 5515161 4.50 11034 10 142440SOS ZECI 748293 275 10,50 5114.7 250 74% 0.43 741527 0247415644 3.93 14503 6 50 CA3189 2701.103712 210 110E01 21.00 93415 6.00 10 70 5tHr1.50 1.1113.170 475 7433 0.30 741518 0147415645 2_03 14599 203 CA32406 1.50 MCI310 1.50 1/4759 310 93425 6.10 11-03 41.14 310 54090 850 7432 031 74153) 0.247415645 1 4.W 22100 3_50 CA329CG 100 MC1413 015 U42243 150SUPPORT DEVICES 12.1.0 4044 1.50 MC:3426 2% 6 CO 6.00 7433 03) 741532 0247415558 093 22101 7.00 won MC14% 0.45 UC569314 .0; 1 1200 14 03 MIN1.75 MC31617 2_25 7437 0.33 741533 0.247415003 OW 221 7.03 04014088 350 1.!014551 310 ouciwat,0.75281633 moo 14.318 6574 1.03 MC4024 550 7438 0.40 741537 0247415670 1 70 4001824 0.48 04008:0 303MCI** 0.711 111.122:0111 075 8 00 14.7991H: 2513 MC4344 5 50 3242 5106883 7439 0.40 741538 02474156E2 2.93 40355 120 DACE 3/0M03340 2.00 111.142:68 293 1245 450ROMS PROMS 15 03 1.1111, 210 1610 7440 CIO 741540 024741594 1 40 40097 0.36 OG303 310MC3401 070 trit42932 190 MC14411 753 921) 3 CO 1620 MIN 2.00 14014412 7441 OW 741.542 0.50741_5687 3_50 400% 0.40 H41366 190 MC3403 0.85 11477284 1.03 ES% 353 28172 4.00 17.734 WON 1.50 7.51 7462A 0.70 741547 0.037415693 3_50 40103 1.50 IC1711:6 675 65310C19 4.00 111187937 1-90 66224 5_50 24510 250 18.02 MHz110 U00003 0.75 74434 1.03 741549 0.90740922 6.9 40101 175 1017611 0.9554050240 9.03 UPC579 2.75 6532 4.W 185030 253 18 432 MHz 1.50 75107 0_93 7464 1.10 741551 024 C50 40102 1.50 1117600 4.00hrtaaf- 5.03 LIPG6QH 203 185490 2.00 75108 093 74C373 4.03 6514 5 50 195E9 MHz 1.50 7445 0.70 741.554 024749125 650 40110 2-00 I0I.7933 2-50Evan UPC115511/00 6321 1.93 745108 1.8023.1:03 104.4 175 75103 1% 74164 1.* 7415E6 0.24 741:925 650 40104 1.20 931113373 4.00191441214 353 UPC118541500 05621 3 CO 745287 24 LW 5100 150 75110 0.90 74475 1.03 7415734 0.30 401(5 1.50 10517555 OW5E531 1.20 XR210 400 130% 17_50 745288 1.10 43133 MHz1.75 75117 1.60 78.8.9 1037415744 OM Din SE MIS 40106 0.413 WOW% 1.40 NE555 022 XR2206 4039* 3.75 745387 2.% 116 5.454 230 75113 110 7450 0.36 741575 0.46 000 , 0 40107 1.C7120 103NE556 056 XF12207 175 6.0382523 1.50 10)(01003 1200 75114 1.* 74157FA 838* 7E4 0.36 0.36*01 024 4as(e LC7133 3.03nat.) 4_03 XR2211 575 1.813 828173 150 75115 1.4.3 741578 953 DISC 7453 03 0.42492 0% 40108 123 1C7431 341011655 1_20 XR7216 6.75 03051 3_00 8251% 1_53 75121 1.40 7464 0.38 74583A 0.704036 0.70 43110 275 1C7137 3.50 185566 1_50 X712240 120092 250 CGNTROLLERS 751% 1.40 7460 OW 741555 0754007 0.25 40114 LF3.17 120 /1E557 1.25 214.06 1.1% ET PROM 7519)0 1.20 741596 964 650 6513 6.03 7470 0.50 049 1008 0.60 40147 2.83 18361 0.60 18135713 450 D4414 OW 63351 8 CO 7154 1000 75154 1% 7472 741%0 0.48 0_46 10:73 0.45 43163 1.03 13353 OW 71E571 3,W 2144150 1.75 C675 5_00 8272 1103 /5159 2% 7473 741591 0.93 14-355 2668 30.00 0.46 4010 0_60 463173 1. 010 274Q38 1.30 8151 650 3131771 2000 751E0 5.ffl 7474 0.50 741592 035 43174 1.W 1E3564 1-10 24424E 1_33 9306 2S161 Oars 75161 650 4711 0.24 P4E0632P 193 8155 3.93 1160 4.00 3131791 23.W 74.5 0.03 741593 054 4312 0.% 4)175 1.0) 1E357 1.00NS531310 150 27441588 3_50 8153 360 F131793 20.00 75162 7.03 7476 0.45 7415958 075*13 036 43192 1.00 1.51100111 450/160534P 170 211426E8 300 2% 75172 4.03 741556 093 9305 (PRO :,S FDI797 2203 7420 055 4314 0.83 40193 1.03 1.743314 033 71%534410 13 214127E8 653 8212 2_23 WI31770 124 7519 150 7481 74(5107 040 1.54337 75189 180 4015 0.70 40194 1.00 0.46OP OMP 350 2114298 8216 1-6025I6 5V 3.50 W017% 003 74.434 7415109 0.40 1513138CN VIO 105 4116 0_36 43244 150 07510.1134 500 37442568 223 8224 0 0.A 251635 550 11102797 27_03 751% 060 7%15 115 7415112 O.* 4017 OW 40243 1.50 16010 225RCM% 055 Dail( 900 8226 4.% 450 430101 15W 7595 150 74* 1.10 7415113 OW 4018 0-W 40257 1.80 1463)) (0WRC4151 21:0 203448 793 332-30 550 5452143 1220 M451 050 74E6 7415114 141318 75452 0.42 06 4319 0-W 43373 1.93 190RC.11% 1.50 91456 3.00 13713 7.60 2554 11 00 050 7403 2.10 7415122 0.70 4020 0 83 43374 1.03 412319 1.80RUE% OM 774409 1203 CHARACTER MASI 070 7415123 2253 7703 4 00 74934 0-55 OW 4021 990WC% 0.75 15E91 0 45553240 9.00 91458CP 100 82514 3.25 GENERATORS 75454 070 7415121 1.40 2716 5V 350 7491 0.70 43% 0.70 80C97 0.75 1117517 1.15SAA1930 16.00 2711034E 203 82530-5 3.50771635 550 754E0 1 50 74MA 0.70 741.5125 050 4023 049WC% 0.75 1413352 130SFF95364 8.03 911040 6538294C 5 320 RO 3-2513 7501 0_36 7415126 OW 2732 450 LIC11_50 70334 0.55 404 0.48 114336 1.83 5450 100 2W413-144 2100 8256 1E103 7507 ass 7494 7415132 0.65 273242 7.03 RO 3 2513 1.10 4025 0_24 114339 040514703391 3.W 7.0 9-50 134570-5 4.0327324.33 6.00 8726 123 74FF.A 0.W 7415133 050 4025 OW Full range 110348 0_60906490 4.00 E%9C.5 4.03 1111.50 8128 120 7436 0.W 7415136 0.45 1.51349C1I 27324-35 500 REAL TIME 4027 0.40 3 60 4.W 8275 %.032764-25 2.80 8195 1% 797 2_90 7415138 055 of 74S Et 11.103601 0.50 CLOCK 87% 120 4728 0.30 951/7646517090 1% E379C-5 4.932716425 6.00 74103 1.90 7415133 OW 4029 0.75 114377 303 3 03 1015318P 4.03 8197 74107 74HC S00256512 750 CPUs 10219 27128-25 360 0.50 74151* OSKee 0.35 1.1433131 8 150 TA7120 110 82E3 4.1:0 /35581744719.40 81% 170 74109 7415147 27256-25 5-00 0.75 1.75 4031 ISseries in Luasass 15014133 I.40 1932CE 6.50 6384 41027256-30 20.00 70555832815 3.50 811556 1.40 74110 0.75 7415148 1.40 4332 1.1:0 1.14364111 110 8115% 1.40 747201 1.50 24604 1050 11727 3.8027512.25 1440 B AU ORATE 74111 O.% 7415151 0.65 4033 1% stock. 1.51119 1W 0.90 ffieM 4.50 650 811597 1 43 7415152 14.150 714527)6 5.00 GENERATOR 74116 1.70 200 4034 2_53 1509 3% TA7222 1.50 9CO2-21.114 8054 8115% 1.40 74118 1.10 7415153 0.55 4335 0.70 Ask for 110384 220 TA73I0 150 1200 01 2 9 1103 14411 7 925120 4_50 74119 1.70 7415154 1_60 4036 250 1613594 1 1 03 154231 120 6_50 174540)3 14 00 C0103116 641 9932 3.00 74113 7415155 0.65 full list. ecizA 1_00 4037 1.10 114.1387 2-70 91413:13 0130 90008 810 17459901 5_03 co,f:LER 47323 7.93 906A 1.60 74121 0.56 7415155 0.65 0033 1.03 03391 1.83 TBASIO 76459332 S3740 1W 74/22 7415157 0.50 zif soclutts 090 *33 2_50 503 KEYBOARD 0.70 4003 2-50 Lmzeazu 1.10 8.0840) 6602 100rms_nit 998 590 74123 0.93 7415158 0.66 093 tamCR rscer 18.00 ENCODER ,P34) 0 93 00393 0_65 reAamm 0/5 6E032 1203 7/459314 14.03CRT6545 910 218447E 950 74125 066 741.51E04. 0.75 401.1 055 L4C641.14 4 00 181923 2.03 6E09 650 233010 2.5099364 800 AY.5 2376 11.50 TELETEXT 74126 OW 74151614 0.75 4012 0.50 1.1.009 1335 184050 20% 9036 10.03 %WIC' 2.75 74128 0.55 741514324 0_75 993* 25.03 /1.M :130 DECODER 4013 OM TTL 6 EC! 1741710 0.48 33.815 10/0 351-C1C 2S06E9365 2.03 74132 0.75 74151534 0.75 44314 0 W 114711 199 283ACTC 275 SAA5320 6 CO 74136 0.70 741519 075 ET -9367 3903 4315 110 28313457 65099369 12.03 SAA TAXI 700 74141 090 74151901 13 4316 0.83 ZEOADART 200 HF S4744911 1600 74142 2_W 741.51664 1.50 119M MC06* 6_50 .0041 470715 5417 003 1£0014A 7.035416845.58 5.445050 74143 2.70 74151E8 1.304748 0_55 *ATTENTION 150 X.091 TVAGLUGEO PLASTIC 2I0513415 7.50MCM17 6.53 6 MHz 3.75 uARTS 74144 270 7415145 1.00 TOES 0.38IA 4110710GRS 7M55/0 700 8 MHz 450 74145 1.10 7445170 1.40 ALL PRICES ARE 5719416.1 8.03 AY -310150101% 3.03 4.360 035 - VE WCOPIO 50376I5M18 15E0 SOUND Er AY 51013P 310 74147 1.70 744.51734 110 4451 015 5V net 0.46 7935 0.50 SUBJECT TO CHANGE 28613C1C 500 VM0071 03518017 310 7410 1.40 7415174 015 4052 O_CO 7936 0_50 7306 0_50 6V 3 DART 900 12 MHz WO 4.513 7415) 1.75 7415175 0.75 4053 003 8V 7918 2053 0.50 WITHOUT NOTICE 74151A 7415181 2.03 0.0.9345 020 454 0 93 12 V 7812 7912 030 SCAS LOW PROM E Da SODLETS BY TEXAS WIRE WRAP 500 (615 115A5 74153 0.9) 7415183 1.913 0:65 080 15V 7815 050 7315 050 74154 1.40 7415193 0.75 4056 056 18 V 78180.50 7919 0.50 tA SC,: no GF IP-, - P -F, 8 Arw 30p 18 9,, 50p 24 H 750 14 10p 420 60p 74155 0.93 7415191 0.75 4069 40024V 70240.50 7924 050 SA SOD 2444lip 281:6- 760 14 on 20 Pn 2847H 1000 74156 0.93 7415187 4060 0.70 IA FIXED VOLTAGE PLASTIC 7092 EC4'... top 'eon op 22,,,22a *40 309 16 on 459 22 on 660 40 Pin1300 74157 7415193 0.80 *61 085 164 15]-:2000 74159 2_25 74151944 075 Turned Pan 4356 040 5 V 78416 0.33 IS V 7944.1.1030 41240 45p 8 pn Zjo ,561 300 4044 28 pin 654 74160 1.10 74/51964 0.75 Low Profit, 4063 0% 6 V76106 0.33 V 73106045 46CR 10 34p 14 pn 259 /8 cn 3Sp 550 43 On 900 74161 OW 7415196 0804069 SocInns 024 8 V 7310E 0.33 12 5'79_12OW T TC44 349 74162 1.10 7415197 CLW 4770 0.24 12 V 73112 0.33 15 V 17115053 TRANSISTORS 74163 1.10 7415211 214352517/9 C5576 1p ,.51 t/PMC :T13765 550 090 4071 0.24 SWITCHING 80107.8 74164 1207415210 0.93 4372 0 24 OTHER 7544411404 801039 129 05938 18a4 84752 T1P41C T13442 140p 74165 1.10 7415241 0.934073 0.24 REGULATORS REGULATORS 755:604 449 BC1OCC 234 CoS5C 244 13FY30 113424 770702 3 Sp 74186 'CL 5% 250 MJ2501 210704 S 499 1.40 7415302 OW 4075 024 1.513,00 1 40 ZENERS EC141 404 CY?) 36p T1P42C 74167 4.00 7415243 3-00 BC161 404 Cr72 30p JAMS 11847 7137% 7 2375p 0.90 43% 0.66 1613731E 250 2 TV 331' 74170 200 7415244 070*77 0% 71494 3 00 80177 329 0131 750 1.1.3101 1154 2000 7Di05XC T1491 725 ACKOdW gp 74172 420 7415215 090 4075 5.75 BBC179 334 80132 EOp 507%955 TIPS 74173 1.40 0 0.2b4 A 5V 78540 91 10/ 150 80E271 154 1319 5U533% TIP125 .1137* 90p 7415247 1.10 4C61 MHO 7.50 400 210%* 6 22p 74174 1.10 7415249 1.10 4032 0% 7104195 1.50 TRIACS 13C113441_ 20p 0136 404 008102 TIPME6 74175 1.* 74/5243 1.10 VARIABLEREGULATORS BC212/1 16p 13139 404 MPF143314 71030% 774481) 500 4035 0_50 7665245 400 74175 16)77374 365,14 13C213)1 D2418 754 6138105 N9160 110 141521 0 75 4035 0.75 1.513054.10 29) 0.50 245457 8 300 74178 1.93 7415153 0.75 4053 120 033171 123 73GHGKCUIC 6.50 IA 4444N 60p 8021411 1841E9 132428 75p MI/SAO 2142194 74179 150 0114COV 704 80327 16p 112448 4434 111319C 710.09 09 7415256 0.93 4093 0 % 1-41317K 2.4078 2% NOMA 294506 74180 13C3313 F2E913 504 111/31B 1.00 741.52574 0-7! 4094 OW 1.133371 2.25 79HGKC EA 5015'90p N72454 216910 74181 3.40 74152664 0.70 4035 0.93 1513507 4.0379GL0C 2_50 BA 100, ?Sp sun 209 FM7/3 404 11P31C 2/(2516 DOW 74182 1.40 7415259 1.20 0096 OW 15 51.!4720 1.40 6.4 500:96p 1381051617 509 F259 404 TIP321 211%054 91128 74104 74152E0 58105475 200 F337 3E9 TIP= SC093 IW 0_75 4397 270 OPTO ISOLATORS 1746500v 1054 374140 1 741854 140 7415261 1.20 448 0.75 9805480 149 rowal 324 710.850 21,13354 4:673 1lD 1-33 155505: 130p 74193 IW 79.52E6 OM 40-69 090 T11112 0.71) T29X0 1102 74191 IW7415773 1% 4501 0.3611074 220 711113 0.70 IOC CONNECTORS DIODES 1.00 117060 UV 74192 1.10 7415279 0.70 4502 OW 111_116 010 wsr SST 1.93 11 260 7 89127 124 0425 = N.6 , .-,.4 so 74193 1.15 74152W 1.93 4503 0.31tea)) 004137 3_60 HeaOr 74191 1.10 MOC3020 1.50 91133 1.75 DISCRETE 0447 104 05132 1-00. -1.3521.7 /4 7415%3 0.13) 4501 016 145p175p 74105 01111 0.70 DISPLAYS P09 90p 2000 2209 2350 0490 go 04914 49 118510117 122 1150 7415230 0.004%6 350 0591 74156 133749292 14_00 4506 0.93 LEOS Recto 9p 1)64148 49 4105413314 lIe O,SP LAYS 1250 157: 190, 66400112 74197 1.107415%3 0.30 1507140% OM 125' tave 825 1930 2000 0495 go 65920 74191 RED 711.209 0.12 2.20 7415236 1.40 3110357 1.03 61466610 210 Ea94 5RIDGES 74199 2%74/5297 14.1.0 4510 05511805001T1173015) 14555831 5.70 GREEN C4814 1200151: 32:-.3.2, 3909 74021 1.10 7415293 1.03 94145377111729 1-03 111311 650 111211 015 19.507 110 24400V -- eamov loop 74251 1.013 7415299 210 4512 0643AN74,01.301 1.00 711729 1.03 YELLOW EURO CONNECTORS valcov20p 3A200y604 644000 1299 74259 1.93 7415231 170*13 1.50 041714131.707 1.03 111730 100 111212 020 ONJg Socket 1464451 304 441495'054 41000 1500 742% 514113610 1.75 14453910 Rext LEDs 7415323 1104414 1.10 150 DIN 416122 22 1,31 33303504 0A540 304 444005. 1000 1/441031/1904 74273 25400 7415324 3204515 1.10 1.44e0.040 200 IRIG,Y1 0.30 .15040-01 232 040 3504 4034 241000350 6.4500 SOp /0A/0007000 74276 1. 7415301 2.03 4516 036 QtU113: DISPLAY DRIVERS 0901.1 332 way 4004 74278 1.70 7415362 120 4517 2.20 Cdow 100 - MIN D CONNECTORS 74279 OW 7415391 1.20 4518 %03 450 111.07033 090 10 LED Itor 232 000.spec00 0 645 4 <7 0.76 9370 4_50 wet we.Ss, ow 74%3 1.% 7415356 2.10 4519 0.32 LIL42074 8000 30 004 41617 21 may 160p 1654 9374 3.50 111.19:03 1/031 742* 3.20 7415391 1.E0 4520 0.83 230 Red 2-25 DIN 41617 31 way 170p 1119 033314 350 610 184 1030 712:0 093 7415364 1 EC 4521 1.15 U192932 190 Grort 2.25 DIN 41612 46 1100 1103315 3.50 Jr911. 1244 7500 009 741060 O 50 7415355 053 4022 053 01745% 11002° 220p 2750 14 11143316 250 111./9504 2- 32 was St PH 1111141 75013 110705366 050 4526 0.70 111230 0.15 2 - 32 vszr, Ang Pan 2350 320p 74351 2.W 7415367 052 4527 090 1.7016118 3% 75191 070 -111%2 0.18 WAILV Ida 175 110 Sao 5441 UDT*184 3.20 75152 3 32 way St Pin 2609 3:09 7 011e rOo 7439A 0.80 7415358 053 4528 070 111226 022 351. t ay 241 ass 3 3754 4034 743664 OW7415373 0.70 7829 110 OTHERS 11132 0.55 %0,04 AN001 ,X.Cel 743574 010 1 DC 511 A 13 1%9 lel- warp Sip ft* 040 1070 7415374 0_70 4531 0.75 2H5777 0.50 0,1117 120 11178 0.55 25.n Ceneunw 7,ee Cern- SW se... 743654 O 70 7415375 0.75 4932 006 13P)M. 1.93 ORR% 120 111319 123 A C 4254 74376 160 For 2. M way ciease 6.6:-..,6 0.0_0.0 1.1 SSCisewt, 7415377 1.33 4534 BP0/21 ORP61 1% 11181 174 1007500 /1.0 3469SO,. 'WO 743E0 1.10 TI IA 0 A CI PLEASE ADD 50p p&p & 15% VAT TECHNOMATIC LTD (Export: no VAT, p&p at Cost) MAIL ORDERS TO: 17 BURNLEY ROAD, LONDON NW10 lED Ordersfrom Government Depts. & Colleges SHOPS AT: 17 BURNLEY ROAD, LONDON NW10 etc. welcome. (Tel: 01 208 1177, Telex 922800) Detailed Price List on request.AL 305 EDGWARE ROAD, LONDON W2, Tel: 01 723 0233 Stock items are normally by return of post.

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PANEL RELAYS SWITCHES DIL SWITCHES RO IDC CONNECTORS EASTERS VE FSO Kniraure. enclosed, PCB mount_ Togg.e. 2 4.250 V ISPST) 4 my 75p 6 way 90p VERO BOARDS 0.1" VERO WONG hasFemale tensile 35p PCB Pi. 60.46x SINGLE POLE Changeover SPST _ 8 way 95p 10 way 1209 x 3% 959 11N Spool _ 380pPugs StuAngle Header Cad 35cren RL6 91209 Cod; 12V DC 110V5 to OPOT 48p (SPOTS 4 way 225p . 75p 2,1 x 5 110p Spare weer with E1.3 Edge 0-50µ4 19.5 VI. 10A3130VDCor SUB -MIN - ROTARY SWITCHES x 110p Combs 80latch Connect0-10414 250 V AC 195p 125p iAdiustable Stop typel 3% x 5 Pen `Mel - Combs10 way 65p 65p 650 1113p 0-5004A DOUBLE POLE Changeover. 6 A TOGGLE 590p 599p 1 pole/2 to 12 way: 2.p./2 to 6 way: 4% x 17 16 way75p 75p 80p - 0-lenA 30 V DC or 250 V AC Sr cr.:cti 58p DIP Board 395p 20 way 90p 90p 90p 185p 0-5mA 3 wde.2 to 4 way; 4p0 to 3 way FROTO DECs R1-113 53 2 Col. 6 V DC 15V4 to SPOT Co, sr64p Vero Strip 95p 26 way 105p110p 1159230p 0-10mA Vembicck 41509 9V91 210p SPDTC.EntrE clf135p ROTARY:ktg-. DP 25017 34 way 115p130p 135p320p 0-50mA SPOT based bp:h 4 Amp or,oti 80p S -17w 350p 1,56-111 205 4 Coil. 12 V DC 1101/7 40 way 140p145p150p 335p 0-100m4 to 191/51 2159 ways 1059 VERO MS per 100 590p50 way 165p170p175p 350p 0500m4 DPDT 6 tags80p ROTARY: Mak-a-Switch) Euricanil 575p R16-114 740 0 Cod. 24 V DC 122V Single Ended . 550 60 way 1959210p225p495p 0-1A DPOTcentreol188p %lake a matiway switch_ Shafting SupcstrP 552 1350p to 37 V1 220p asserriUy ha actustable stop. Ac- Eloutde ended . 60p 0-2A DPDT biased both Ware Wray SfE 155p 0-25V ways 145p commodates up to 6 wafers (mac 0ALD ETCH EURO CONNECTORS ASTEC UHF MODULATORS 6 pole; 1 2 Veal, Wee Wrap 0.4 255p RESIST PEN 0-501./ AC 6 MHz Standard 375p DPOT 3 poetic rs' DP switch). Femak Sockethide Pkm %tech:mem cagy 99p s.,,Ity to 15.0p 0-300V AC E PAH. Wsdebend 450p entrVon 185p VERO TOOLS Stn. Angle Sot Angle 4 -pole 2 way 220p make before WAFERS: Soot face waters 150p FERRIC Pau Fins Fro Pew "VIP' BUZZERS. manasture. soil state SLIDE 250 V: break)tofathe above switch Pn insertion tool 185p CH1ORKIE DIN41617 650p each 6V. 9V & 12V 90p mechanism E. bag Arhydrol-s 31 way 125p 175p DP01 1 A 149 CORER CIAO BOARDS -- OPOT 1 A cef115p 1 pole112 way; 2 pole/6 way; 250 - 50 P&P D0141612 2+32 CRYSTALS PIIMO TRANSDUCERS 3 polel4 war 4 pole/3 way; Fire sive- A .9 2009 175p 220p OPOT h A 13p - 32.753.H2 100 992720 95p 6,2 way 70p gf444 sided Pied EDGE 131/41612 2.32 PUSHBUTTON %taws DP 44 Synich to fn 55p 6".6" 1009 1250 COPOECTORS A ZZSp - 1859 2309 2000M 370 ULTRASONIC TRANSDUCERS 6A Spacers 4p. Screen Bp 5"=12 00.41612 3.32 459044 370 40 kitz 475p pr. with 10 mm Button ROCKER SWITCHES 1759 2259 2= 6 war - 75pA-8 11.8.12 265 SPDT latching 1 50p 280p290p295p300p 1-00611 275 LOUDSPEAKERS ROCKER: 54:250V SPST 35p D a. SOCKETS 2.12 way - 1600 C DPDT tatchina Low Wee Turned2.15 way - 1659 r1_251.944 450 Mr/4mm 0.31V, 82 200p ROCKER: 10A/250V SPOT 450 1.51415, 525 NoProfWrap Pei 2.113 way175p 160p 20% 2Sin. 25ikm. hint 989 OPOT moment ROCXEFt 10A/250V DPOT cioff 1.61.81 595 E 2.22 way 200 170p 2%M. 404. 642 cr 9.04 95p 200p 105p 8p 20p 18p 1,5MOM 545 ROCKER< 10A/2.50V DPST with 14 10p 28p 23p 2.23 way 150P - DM PLUG RIBBON CABLE 1 543211 200 Mini Non Locking neon 95p 16 10p 40p 28p 2.25 way250p 245p(fteackal price par foot 2.CMIM 225 ACCESSNISA Push to Make 15p THUMBWHEEL 16 16p 40p 33p 2 28 way 1130p - P0/ Se;der (DC WAY (2551 COLCUR 245704 200 ORDERS P.i-sh to Bleak 25p 20 209 589 37p 2= 30 war280p - 14p -n 40p 95p 10 150 2Bp1175M 150 Just phone your orders 22 22p 60p 399 2.35way300p 14 20p 34p 257941.1 95 DIGITAST SWITCHES - 16,;;n459 100p 2 858414 303 24 25p 6139 429 2.40 way3209 through. We do the rest SWITCHES Mae front mounting - 24pin 85p 135p 16 251, 409 s_OMHz 140 Assorted Decade Switch Module 325p 2E 289 789 52p 2. 43 way400p - 28P. -105p 165p 20 30p 50p4 032101. 290 600p Tel: 0923 50234 cotmos B.CD. Snitch Module 315p 40 30p 89p 72o 2. 75 way - 40or2013p 225p 24 40p 65p 4.1943511.1 150 75p each Mounting Cheeks tye pen B5p ANTEX SOLDERING IRON 28 4a 70p 43361511 100 BT TELEPHONE C -15W 600pCSI 620p 511 ZIP TEXTOOL 28 55p 75p4 Kam: 200 TRANSFORMERS SOCKET 1311 SOCKETS 34 60p 85p 5.C.tmiti 150 0-18W 620p5.5255/ 5.185V.H4 300 CONNECTOR 3-0-3V: 6-0-6V: 9-0-91/: 12-0-12V. Spare tips. assorted p:re 100p 0.1" pitch 24 pm 550p 40 709 90p 15-0-15V 100 rnA 130p 28 on 695p 5.2428574 390LJU 1/4A Mini Line Master Spare Berrents 245p 20 way 50 859 110p6.0400 140 PCB els:ranting; &Grimm: SO. Bobbin Iron ward with sponge 1959 65p 40 an 800p 64 100p 135p6.14411461 140 435p 3VA: 2 x 61110.254: 2 x 9V /015*- 2 'D CONNECTORS miniature 5.5536461, 225 LJU 1/6A Mini Line Slave x 12V 03.124: 2 a 15V/0.2A . - 235P VOLTAGE REGULATORS SOLDERCON PINS 7_01.1117 150 6VA: 2 = 6V PISA; 2 x 9V /13.34: 2 = 9 15 25 37 7_165.4111 175 295p 1A Paste Cas-ng for awing 511 12V 0.25A 2 x 15V /0_24 280p 10220 MALE way way way way 7.661/712 200 Standard Spit Batten type VE -VE or OIL Sockets 8014116 140 UU 2/4A Line Master 370p 5V 7805 Sop 7905 SOp 100 p-ns 35pSolder kegs 55p 130p 12001513p 8,382111.1 395 6VA: 2 x EV /0.54; 2 x 9V113A4: 2 UU 2/6A Line Slave 250p 12V .11.3A: 2 x 15V A3.254 250p By - 7908 60p 500 100p Angle pins 110017592250300p 8,85723M175 12V 7812 45p 7912 50p PCB p;rs 95p 100p 150p250p9.00kOM 150 UU 3/4A Flush Master 370p 12VA: 2 = 4V5 /143: 2 x 9V 03A6; 2 45p 7915 50p ALUM BOXES 10_01.111.7 170 12V /OAS: 2 x 15V .1344; 2 x 20V .174315V 7815 10C LJU3/6A Flush Slave 240p 18V 7818 45p 7918 50p 3 . 1" 75p 10 241.0M 200 345p 135p P&P) FEMALE 10.7 150 24V 7824 45p 7924 50p 4 x 215 x 95p 120.11.1. 150 UU 1013A Dual Splitter 475p 24VIL, 2 x Gil /145; 2 9V /142: 2 100mA 1092 Ft4st4 Camp ac 2%. 028 115pSolder tags 90p 12501800275p 12V Ilk 2 x 20V /045 3850 1609 P&P) 12.5281 300 4 -way BT plug 65p 5V 78505 30p 705 50p 4 x 42" 110p Any.e. pons 15002000260p390p 143151441 I55 50VA: 2 x 6V/4.1/42 = 9V /2A5: 2 x 12V 6V 79106 30p 4 x 4 x 214" 135p 12A: 2 . 15V /1A5: 2 a 20V ilA2: 2 PCB pea 100012501950355p 15.0100 200 8V 791.08 30p 5x 4x 1/5"115p 15_02.01: 200 EPROM PROGRAMMER 25V /1A: 2 x 313V !DAB 5200165p P&P)12V 781.12 30p 79112 50p 5 4 2%"135p IDC 18.011Hz 150 SOYA MULIIRAIL, 5V/5A. .121/. 15V 78115 30p 79115 50p 5.2%.1%"100p COVERS 659 68p 70p 85p 18.43211 150 Copies up to eight at a pass. 2716 .251/. -5V. -12Vto 62001650 P&P/101.7660 245p TAA550 500 5 x 2)5 x255"145p 20.014Ha 150 to 27256. EPROM type is set by 100VA: 2 x 121/ t4A: 2 . 15V f3A: 2 151309K 135p 11341412 150p 6 4x 2"135p 25vray17' CONNECTOR RS232 I9S6Ealett 150 20V /2A5: 2 x 25V 12A: 2 x 30V /145:LAI317K 250p TL497 1859 6 4 x 170pJumper Lead Cable Assembly 24.01.04.7 150 switches. Erase is checked auto- 2 . 50V /1A 955p (7551 P&P) 043171 99p 781105 .5V 5A 550p 7.5 x 3" 2013p 24 5301.1Hr 325 18" long. S.ngle end. Male 495p 76 691/ 150 matically. Simple control. Alpha IP.S. P&P charge to be added over and abo- 1.113235 450p 781112 +12V SA 640p 8r 6 = 3" 230p 113" long. Srigbe end. Female 525p 27.56814 170 ve our normd postd charge) 132337 175p 72I-0 -51/ to -24V 695p 10 x 4 x 2659 liquid crystal display. Checksum 36" long. Double Ended. (44.1 1025p 27_1494 190 LM723 30p 7350 225V =241 785p10x 7 x 3" 3130p 33E4657IA 175 facility 6 hex digits. FAST or NOR- 4071 20 4531 120 RC4194 375p 7E640 220p12 . 5x 3" 290p 36" long. Double Ended. PIP 995p46 Oliftr 170 4072 204532 65 RC4195 160p 12 .8.3"325p 36" long. Double Ended. 1AF 995p 100.01100 245 MAL programming £385 CMOS 4073 204534365 4000 20 4075 25 4536250 OPTO ELEC- GAS & SMOKE AMPHENOL CONNECTORS VIDEO MONITORS 4001 204076 60 4538 70 Detectors IDC solder o 1431 14" Standard Colour £175 4002 20 4077 25 TRONICS 4539 80 24 way IEEE Rug 465p 460P o 1451 14" Mecnum Resolution ColourC225 4006 70 4078 254541 95 LED TGSB12 695p 4081 24 way IEEE ski 485p 480p 4007 20 204543 65 0.125" TGS813 695p o 1431 14" High Resolution Colour . C359 4008 60 4082 36 way Convorees 20 4544 150 111209 Rod 10p o 1431AP Std. Res ROB -i- PAL & Audio £199 4009 40 4085 60 4548 40 Sockets for above ..150p 0049 375p390p 4010 01211 Gwen 14p 40 4086 60 4549390 T11.212 Yellow 14p 36 way Convc.rics o 1451AP Med. Res ROB PAL & Audio £255 4011 20 4089 120 4553210 TI1213 Amber 14p sit 480p 450p 4012 20 4093 25 4554 190 4013 30 4094 70 0 2' o TAXAN KX1201 12" Hines Green ... E 85 4014 50 4555 50 ' .220 Red 12p COMPUTER ACCESSORIES CORNER 4095 704558 50 4015 40 .222 Green 149 1.405 o TAXAN Type 620 Hi -Res RGB Colour. E269 4096 1004557 250 226 Yellow 14p o Epson EX800 Printer 4016 25 4097 260 1.315 o TAXAN Type 625 Ultra 16 -Res RGB 4558 120 _ Ped 56p o Epson FX800 Printer 4017 454098 70 4018 55 4559 340 = - -P.G 1DOp o Epson FX1000 Printer 1.439 Colour £319 4099 110 4560 110 CvY 1013p 4019 35 4160 o Epson 10800 Printer £429 4020 95 4561 104 Tr. colour RON 85p 50 4161 99 oEpsonLX86 Printer 1.189 .4562 350 HI -Bright Red 95p o Philips 14" kfires Colour £209 4021 55 4162 o Epson Paper Roll Holder C 17 4022 60 994566 1E0 HI -Bright Green 100p 4163 99 4023 20 4568 250 HI Bright Ye3low 95p o EX800/1000 Colour Option C 55 4174 99 o ZENITH 12" Hires Green Monitor .. . E 69 4024 35 4569 175 RectrogL R. G & Y 35p o EX Colour Ribbon E 18 4175 105 4025 20 4572 45 Recte-g.Skatre o FX80185 Tractor Feed Unit E 35o ZENITH 12" Hires Amber Monitor ..E 72 4194 105 4026 90 4580 255 Red. Green. Yefew 18p o FX/LX800 Single Sheet Feeder 1.139 4027 30 4408850 TnangutarR&G 18p 8504581 125 o FX/L01000 Single Sheet Feeder £149 4028 404409 4582 Securicor Carriage on Monitors E 7 4410725 99 Infra Red o Hi -80 Retilts - Set of 4 Pens £ 7 4029 45 4583 100 LD271 lentil 46p 4030 20 4411 750 o 10800 Tractor Feed Unit E 39 44128054584 40 11132Iemtitl 52p 4031 125 4585 65 SFH205 feletecter11009 o DC80186 Tractor Feed Unit £ 20 4032 65 4415590 4419 4597 330 1117BIdetechar) 55p o 1X130186 Single Sheet Feeder E 49 4033 130 280 14.38lest1 50p 145 44227704599 155 o Brother HR20 Daisy Wheel Printer £349 4034 40085 111100 {detector) 90p SPECIAL OFFER 4035 70 435 860 SO o Panasonic KX-P1081 NLCI Printer £155 40097 45 4036 250 4440999 7 Segment Display 0 Panasonic KX-P3131 Daisy Wheel 1.245 4037 115 44503504009842 O 1704 .3" C.An 120p 1+ 10+ Securicor Carriage on Printers E 7 4038 110 4451 35040100215 01707 .3" C...Cth 120p 4039 40101130 FNE1357 or 500 100p 270 4490450 1/1321 .5' C.An 140pCan in at our retail shop for demonstration on any of the above2764-250nS 350p 325p 4040 45

ZenithElectronics.® cRiELECTROriotNICS LTD op Kits-Modules-Hardware CHRISTMAS SPECIAL 10 -Channel variable speed running light Kit. drives LED's or Mains lamps - plus 2 -FREE LED display boards and WRITE OR PHONE LED lamps. An ideal festive project. NOW The following are examples of our proven product designs: * High quality touch dimmer 500W R/Built £12.99 * Selectable tone generator, 9-12 V operation £ 5.50 FOR OUR FREE * 3 Note Electronic Door Chime unit; 9 volt operation, 3 melodious tones; variable frequency. Kit £9.83 * Miniature FM Transmitter, 60-145MHz. Kit £6.95 PINK R/Built £8.95 * 3 Watt FM Transmitter, 80-108M14.7.. Kit £13.99 R/Built £18.99 COMPONENTS * 300 Watt Light Dimmer unit for 240 volt mains lights. Kit £6.95 * 4 Code Digital Code unit plus Key Pad -select own CATALOGUE code; 9 volt. Kit £15.95 * 5-100 Wan Electronic Loudspeaker Overload Protector, adjustable. Kit £11.11 * VU Meter 10 LED indicator, -5 to +12dB range. Kit £12.59 * Automatic light controller: automatically turns on and off lights at pre-set times and triggered by darkness. Kit £25.08 * Mains Wiring and Metal Detector, R/Built £11.00 * Zenith Speech Processor P-202 R/Built £25.00 * 18 -Wan Car/Home Power Amp_ 12-V. Kit £13.23 * Amplifier Power Meter, 10 LED indicator from 0.25-100 Watt Input -9 volt operation. Kit £9.52 * Light sensitive relay unit; variable sensitivity trigger control; senses light or dark -selectable. Kit £8.45 ALL KITS CONTAIN FULL INSTRUCTIONS: P.C.B.s AND COMPONENTS ALL PRICES INCLUDE VAT AND POSTAGE & PACKING. SILL rat OVERSEAS ORDERS -ADD 10'. TO ABOVE PRICES. PLEASE SEND CHEQUE OR POSTAL ORDERS WITH ORDER. Data Pack Zenith Electronics, 14 Cortlandt Business Centre, Hailsham, E. Sussex, U.K. BN27 1AE. Tel: 0323 847973 Telex: 878334

_ fj7___ XEN-ELECTRONICSTEL. 0983 292847

LC'S Orange .21 Ti,I21 .34 15 Vi Sit.1.02 II -.F 4Xed _ _ _ 08 400108 .....12Wort 15 714126 .34 IS W Pk.9 .. _390.010f 100V 08 4011u8 _.....123 =In Dia 710310 .30 2510 Pkg _ .2.1500220 63V ce 4011 12 Red 13 718320 .30 00470 103V 03 4.017 .31 Cr,..st 13 2I/2546 .1.18 CAPA4Rom 0.10 63V 08 - 4028 29 Orr -age 21 2n30e5....47Radii Lead 0.1%sf 63Y .17 4040 .38 Yams .13LC. Sockets 7--20 50V -- -080.330 630 .33 4053 dr Bred Velsree 1-.1. Cost 320 63V- -. .11 0.47,,F64, .17

406.6 . 6 Wzr . _ . -05 4:74.6-3V -- -438 4 Regulators 07 330, 16V ....04 4081 + 5IA 36 8 Way .350A-C4U 1.135 6 t.6A 68 14 Wey ...... 1147,0 10v ....06 Resisters Carbon Me 7 .30AP,0 _ .1.68 t6 War /3470 25V _ ...06 0.25Watt 5% 121.5A....36 eicr 36v .08 1 4 To 10610 sic, 02 -:-.. - - -4-°° +15 IA .. _ .36 18 MI 0.5 Walt 5% s.. - : 7.- 7_30 . 24 /A : .66 20 wn. _16 470 63V _ ...DB _ _ 102 To WW2 rad: .04 18 47Af 100V . _17 - -- A1 -5 IA . ...39 22 WA, 3-30 Ilk.f 35V ...AG - 12 IA . . . 2.10 24 War 20In, 63.,, 06 - -25 -15 IA _39 78 Wn - -23 .--- ,,- - "*,, Teneister Bead 1117C/ '''' 1.87 _2411 .3940 WO -33 '."-,:himy - 11706" CA1472W 14.74.21 195 L074C?... _51 c ,/.-- -',. T p. k2633. _3.69 4-8'' '-'1" 0.1A_ .. _28 '`.. 6 '''''SWay 2 103AF I8V -- -08 /100f°45 25V35,, iT3ts60.5284 __.P20 6 12 0.11A ..288 wa, . .16 ::-.4107/3 1.444.8..4".4c...... 0.0pA4FC9 Wor4

+15 0 lA -36 14 Wry _ _28 5.1.4900P 2.13 /6 wn. 32 1030' 5GV - - -19 1007 _ 30 -50.11.-..30 115 .30 '9-926Ce- -104 -120.14...30 18 Wry. -36 1CC'sF 63V...06 - 21 5A/2 ------Diodes220010V-15 0.1A.- .30M Wei 40 333,,c 163_.19 30 194001_ ....05 -50 HUNDREDS OF LOWER PRICES .05 22 Wt.' .44 4760 16V ..25 //gm 24 .05 BCI07 ..16 :....:4, 470..f 50V , _.40 -103.37 /1,005 Trassistors602 .50 HUNDREDS OF NEW DEVICES 11,007 ./36 80108 .21 .."0 -'°'4700 623 ..63 20X0 .50 1115401 -_...1280162801090 _1940 'Ve, -9° 10000 103 _23 ..05 10300 163 _27 from theU.K.'s number one 100% components shop genes Diodes 80212 - .05 0 TYRA rad. 22020 16V ..45 Project Kits 2V7 .410 ._.D5 Bc_5460 _./34 9 W Sit - 43 miss ',sad RS232 10 Commies Ca-arr..er

no gimmicks, no gadgets, no computers, just millions of 531 .4 W - -05 BC5564 _.04 9\4 F312. -.. -38 4.70 53V _...OS Orly ... _ 18.40 715.4 W - --°880233 _42 9 W Caro - .98 1Ccf 35V . .11 280 amid Cerste41.E.s.,--j, - ...06 Es -55/ ..54 1 components, all easily available by mail order, calling at shop, 931 .4 W . 1510 5 - -60 474F 753 _ ...10 4/4193.7 10V .4 W ...06 6E259 .58 15 W Pug- -53 103.4 2511 _18 ICJOr4 ...... 20.45 or creditcard telephone orders. Just pick up thephone, ora 113 _4 W ._ _0565150 49 15 W 40,44-1-0747-f- 10V _ 22 1: -.rasa -6. Tacerreastre

1.1 -D'S 633520 . .1.61 28 W S91 -60 101700 10V _ .31 10e5ar .144dde Font pen, toget the catalogue(noSAE is required) - posted 5 Med Elka 6380-_-_4.10 25W P.3 -53kuuftedPay. k1 Orgy -23.52 25 W ea, _1.16 FR EE to any country on the globe Red 13 J112.- _ ..52 ester Far 13,1.1 LCD -V-,..1i1.- I:-..:"...... - Green 12 417F61110 _ .1.44 Pat Mews 5.7.5 rim Pt st CI Ori`y _ 1433 WHO SAYS WE NEVER GIVE ANYTHING AWAY? AN OFFER WHICH CAN ONLY LAST UNTIL CRICKLEWOOD STOCKS ARE EXHAUSTED: THE ELECTRONIC INDUSTRY TELEPHONE ELECTRONICS LIMITED CODE BOOK AND DIARY 1988 40 CRICKLEWOOD BROADWAY Y OUR§ABSOLUTELY FREE WHEN YOU NEXT PLACE AN ORDER WORTH £25 OR MORE. LONDON NW2 3ET ALTERNATIVELY YOU CAN ORDER THE DIARYON Tel: 01 450 0995 Et 01 452 0161 ITS OWN AT A PRICE OF £7.25 (VAT ZERO RATED) Telex: 914977 ORDER NOW AND DON'T BE CAUGHT WITHOUT IT!! Mai or Telephone Orders Only Please To: DEPT. 13 Samuel Whites Estate. Bridge Road, Cowes, Isle of Wight. P031 7LF Please Add El For 1st Class Post and Packaging, and 15% VAT to Total VISA arria4 drre Stock listing evadable soon. Please send SAE to be put on the mai fist 9 EE December 1987

1988 CATALOGUE SWITCHED MODE PSU OUT NOW - 88 pages of bargains from _ Astec type AA7271, PCB 50 x 50mm resistors to disco mixers. Pricein- has 6 transistor cat providing current cludes latest bargainlist,discount overload protection, thermal cut-out vouchers, order form. Don't be with- and excellent filtering.Input 8-24V out your copy - send £1.00 nowil DC. Output 5V 2A. Regulation 0.2%. NEW THIS MONTH £5.00 30WATT AMPLIFIER Z806 Sturdy steel case 305 x 300 x WIN 120mm containsILP HY60 amp Sinclair module, controllpre-amp PCB, PSU, small monitor amp + speaker £12.50 + E3 carr A 600MHz Z807 As abovebutincorporates MICROVISION cassette deck built into top of case, We now have a supply of cases, alsobatt.back-up(3 x 6V 1.2AH complete with aerial at the special sealed lead acid batts). Push button low price of E5.00 FREQUENCY COUNTER! bank on front panel controls cassette, We have a quantity of these units power etc. E22 + £3 cart in varying states. From labels at- Full details of these on BI- 33 tached to some of the PCB's it K568 GIANT PLASTIC PACK seems after assembly on the pro- Approx 1000 pieces- standard and duction line they did not function IN THE NEW miniature PCB supports, self adhesive correctly. No attempt has been ribbon cable clips, straps, ties, cord made to repair them, though - in- clips. This lot would normally cost stead the following parts were removed: STYLE around £50!! Our special priceE12.00 a) RF Tuner 1(563 Cable markers lident sleeving) b) Vol control & switch Over 1,000 pieces, all with either letter c) ZN401E chip or number. Assorted colours and sizes 2666 2 x PCB in good condition WINTER from 1-5mm dia. Over 50 different! with 2 x CRT that have been re- Pack of 1,000 £2.50 moved,but maybe repairable. RECENTLY ARRIVED!! Conductivepaint(15m1bottle A major electronic distributors discon- £3.45l will probably be needed to 1987/88 tinued lines, all being sold off at LESS remake contacts. With diagram & THAN 14 PRICE!! - boxes, cases, con- notes E6.95 nectors. LED's switches, DIP boards, RF Tuner £6.95; ZN401chip cable ties etc. All goods detailed in a E9.95; Vol control ÷ switch with 16 page supplement available now knob f 1.00 Cirkit FREE MOTOR + SOLENOID Z659 Motor, high torque 6V operation CATALOGUE with integralbrass gearbox giving 6ORPM. Shaft 18mm long x 8mm dia with flat. Overall length exc. spindle lb :"?_ 80mm. Dia 33mm. Ideal for robotics applications,beingextremelyhigh PACKED WITH NEW LINESI torque £2.75 _IP Z738 6V solenoid single hole fixing. 46 x 16 x 18mm. Slug is 45mm long 6.5mm dia with tapped cross hole and Z652 Coin acceptor mechanism. Made slot. 25mm pull. £1.75 by Coin Controls,thiswillaccept 2 new HF Receiver kits various size coins by simple adjust- SPEAKERS 2578 Sub -min speaker 30 x 30 x 3mm ment of 4 screws. Incorporates various thick by Fuji. 1611 0.4W. 60p ea; 10 5 and 50W RF Power Heads security features - magnet, bent coin £3.70 25 £7; 100 £22; 1000 £180. rejector etc. Microswitch rated 5A Z575 70 x 45mm 45R 0.5W 55p ea: 240V. Front panel 115 x 64. Depth 10 £3.30 25 £6 100 £20 Oscilloscope Digital Storage Unit 130nm. Cost E10.85. SOLDER Our pnce E4.00 500g reels resin cored. 18g . £5.95 SOLAR CELLS 500g reels resin cored 22a .. £7.95 Component Packs Giant size. 90mm dia giving 0.45V LOGIC PROBE 1.1A output. £4 each; 10+ £3.50. For TTL, CMOS etc. LED and sound in- Mega size - 300 x 300mm. These indication. Pulse enlargement capability 12 new books corporate a glass screen and backing allowspulse directiondownto panel,withwiresattached.12V 25nsec. Max f = 20 MHz 4-16V. UP 200mA output_Idealforcharging 2:1M £9.99 nicads. £24.00 Temperature Controlled Irons SPEECH CHIP 'NEWBRAIN' PANELS Z733 SP0256A + index chip + ULA 2494Motherboardmicroprocessor chip as used in Currah microspeech. panel 265 x 155mm Complete PCB for Easy to Enter Competition Cct and info for using SP0256 with computer. Z80, char EPROM etc. 68 Spectrum. ZX81, BBC, VIC & C64. No chips altogether ÷ other associated info on other 2 chips. All 3 for £3.00 components, plugs, skts etc .. £5.50 Special Offers AUTO DIALLER 2495 RAM panel. PCB 230 x 78mm Sloping front case 240 x 145 x 90150 with 14 x MM5290-2 (4116) (2 miss- contains 2 PCB's: One has 4 keypads ing) giving 28k of memory. Also 8 LS Quantity Price Discounts ONLY (total 54 switches) ÷ 14 digit LED dis- chips. These panels have not beer. play. 2 x ULN2004, ULN2033 & 4067: soldered, so chips can easily be re- the other has 12 chips + 4 power moved if required £5.00 24 hour order line £1.20 devices etc. Case contains speaker. 8 Z679 Keyboard. 62 keys onally core cable 2m long with plug. For use chassis 260 x 90mm. No PCB £6.50 with PABK. £9.00 Z670 Handbook 204 pp. Useful appen- PCB Prototyping System dix (about 14 the book) gives tech, info PANELS £5.00 Z620 68000 Panel. PCB 190 x 45 be- 'NEWBRAIN' PSU CB Rigs lieved to be from ICL's 'One per Desk' BRAND NEW StabilizedSupplyin computer containingMC68008P8 heavy duty ABS case with rubber feet. (8MHz 1618 bit microprocessor, + 4 Input 220/240V ac to heavy duty EEEs of Discount Vouchers ROM's,allinskis; TMP522OCNL. transformerviasuppressorfitter. 74HCT245, 138, LS08, 38 etc. £5.00 Regulated DC outputs: 6 - 5V at 262532k MemoryBoard. PCB 1 -2A; 135V at 0 3A; -12V at 170 x 170 with 16 2k x 8 6116 static 0.05A. All components readily ar-eec- Available from your local newsagent or ible for mods etc. Chunky heatsink has RAM's. Also 3.6 V 100 mA 2 x TIP31A. Mains lead (fitted with direct from Cirkit at the address shown memopack nicad,13 other HC/LS 2 pin continental plug) is 2m long. devices, 96w edge plug. 8 way OIL 4 core output lead 1.5m long fitted below switch, R's, C's etc. £4.80 with 6 pole skt on 0.1" pitch. Overall Details of other similar PCB's in latest size 165 x 75 x 72mm. list £5.95 oaf l0 for £40 Al prices include VAT; just add CI.00 P&P. VISA krn Arrg.es order E10 (Pio IT141. CWOI. Officid 'MEL orders from schools etc welcome - ten invoice charge £10. Cirki GREENWELD Ois slx.p has enorroots stock of components &A is or., Cirkit Distribution Ltd. ELECTRONIC 9-5.30 Mom -Sat. Came and see us!I! COMPONENTS 443E Milibrook Road Southampton Park Lane, Broxbourne, Herts EN10 7NQ S01 OHX Tel (0703) 772501/783740 Telephone (0992) 444111Telex: 22478 EE 10 December 1987

OSCILLOSCOPES OSCILLOSCOPE BARGAIN TELEQUIPMENT 083 Dual Trace 501.1Hz_ Oday .501).,pa-pc% colsxr. c.;,...:. gE,.....m, 15!!i- S';,-.;;;:,.... _ofitil.der oi Sweep. Vi5th Marcia' £350 withrrtim-,a' . .. OrayES5".ez-v- first COSSOR 000150. Dual Trace 35M.Hz. Sad State...... _- .0 K rie.macrn CRT Res:wet Arlaysa. Model 467. f Portable 8 i 10 cm display with marvel .. E180 wedwith 2 basesand manual S.E LABS 5161111. Duel Trace 113&012 Sold State- (mg vi ONLY £125 each P: --__'a AC or Extend DC operation 8.10:m &s- £150 LARGEAR Colots Bar Generator KG). 8 Test patters r' '.-'-i. Msuul ONLY £40 eich N!1 7E1,2 _ 7LIcYiT 061. Dual Trace IDIAHz. Viith (P&P £41 £150DISK DRIVE PSU. 240V lfi; 5V 1.6A & 12V I.5A etot TELEO. °YE'. T 043. Dual Trace 151.4141. With out. Sire: W125rrrn. H75 ann. 01130mm. Cased Un- otIN1°.e Marue £100 used ONLY E10 (P&P El ttoostt TELECIU:P.,E'i 7 SE4A. Shale Trace 101.11. Solid OWERTY KEYBOARD. Cam. ASCII Coded + Un- e Send Slate- 'i''''.'a- -: -- -. £00 Coded Keypad & Fur:fon. Keys. Receares -+!- 12V With info. Un-uset £2.5 !P&P E4; COMMUNICATION RECEIVERS Op*&sAE OWERTY KEY=_' n :.7..s n LYNX &OM). Push to Reoal RA17L SOOKHz-30Ltilz . _ only £150 each make. Gar'.. ONLY E5 ea._ IP&P £21 Ot with Meisel for CATALOGUE Eddystone 7304 4130KHz-34:ALHz .only £110 each DISK DRIVE .5'. ..,...... HEIGHT BEI Trek DoubN Ath Ma ell. Sided. Double De-omy. With Manual. Used RDERS: RING IOU 567 8910 -24 HRS. (P&P £51 EEO eaxh NEW POWER STROBE KIT MICROPROCESSOR TIMER KIT MULTIMETERS 9' Black & White Monitors horn £45 AVO 9 Mk4 fliethcal to AntS Mk4 bat soaked dffte SWITCHED MODE PSU - '-12V 0-25AI 5V ISA Desgcso to con- andy1 Complete wilt Batteies b Leads L55 etc (20 each P&P £3. Desdred to prodace a trol 4 outputs highintensity light AVO 81,0)2 Complete:Anti 6.--nefes Er Leads ___. E45DATRON 3000 PROM COPIER IwPe' UP to 101 £150 molt P&P E7. purse at a variable fre- dependently Above Items in GOOD WORKING ORDER - emu,- quency of 1to 15Hz. switching on and rice not Al hence the prep. ISOLATING TRANSFORMER 240V In - 240V Out. This kit also includes off at preset times AVO TEST SET Rio 1 Iliffite.y version of AVG Br 500VA E15 e P&P 15: IOOVA £6 ca. PEP £2 24V circuitry to trigger the over a 7 -day ci,c1.. Cc.m::ete wok Ez7.-c-es. LSI& 8- CarrYis3 Case.. 1.65 Out SO5VA ER ea- ?&P £5. 200VA Ell P&. £4 display of strobe front an thitemal LED -_=ADS t_--1- t far AVOMETERS. Rod Er Stack time and day, easily programmed via 20 way NEW EQUIPMENT source lee a ioudspeaIcerl via an opto isolator. ... r - PmA-6 'cf.,. ,21 __ ._ . 13 HAM ,_,...-.,---- - , -, - , ...... LtbLUrr. ci.: -. I TZ,:t 50 keyboard. Ideal for central heating control in- - - r - .r_ ...-.. cruding different switci-Ang time for weekends. 13eLay Sweep. Cormorant Teste £553 A. - EIO Battery back-up circuit. Includes box. 18 time HAMEG OSCILLOSCOPE 203.6 Dual Trace.20.'m, imoc;a:r : _ .3S a warning Compenett Tester with 2 probes £314- The kitin- settings. STEPPING MOTORS beacon in- secr.u.t _s_ CT6000IC £42.90 cludes a high q_... -ents, con- A4CIFW Models AvA4,1 XK114: Relay kit for cr6000. includes PC9 7....-:.s ::::: -:-.. -_- :, C.... i; -sc..,:ecl nectors. 5Ws = eno r_J assembly and one relay. WA accept up to 4 Loupe Es -,-,- BLACK STAR FREOUViCY COUNTERS P&P 14 instructions. 5...- . 240V ac Tare: relays. 3A240V clo contacts £4.30 Type)._ 612 Steps per ter. 3 Phase. 12-24V In0 wokiifalear 100-10MIIN E 99 75.50645 701 115:4.3011icral rerayS £1.80 u_so Vetost 600-600MHz E126 XX124 STROBOSCOPE KIT t12.50 on 5V) E2 ea_ 5 off Typo 3. NORTH AMERICAN PHILIPS 24 Steps per re.r. Meteor 1000-1Gift E175 VERSATILE REMOTE 4 wee 5V 33Arms 0250ree 1L233PP$ £6.,.. RACK STAR JUPITOR 5030-00CTION GENERATOR. ELECTRONIC GUARD DOG KIT CONTROL KIT T-4,3 4.200 Stops per re, 1371 0 Wee} Torque 4 or Si"*Schureariaingle. 0.1Hz 500Kftz P&P £4 E110 Ore of me Dec: inch E4 er_ This kit _clads HUNG CHANG DMM 7030 335algal- 1-,-4-, rents to a turgIar at a Type 7. WARNER 24 Saps Ire rev. 3 Rase 16 wire!. -., -8 all components wen" rock Hand10 Arm AODC 0.1%. C.,:,,,:'e-,- tl es 2SV. tfoidng Torree 6 at. inch 5 ett. 1+ tranSiOrrner) with barmy leads. P&P £4 £39.50 pro:ridn'lesthee to make a SenSi- AVO TRANSISTOR TESTER TT1613 - _ _ withoutthe As above D1.11.1 6010. 0.25% £33 50 IR receiver Harcheid GOINOGO for In-Ocu Test g. Con p'ete with Thekitwhen tive with 16 logic 13_n.-res. feeds Er ireStAXO0r6IPBP £31 OSCILLOSCOPES PROSES. Switched x 1:a 10 assembled can be outputs 10-15VI which with suitable interface tfOWONLY 02 =:&PE2 £11 connected to a doorbe pressure ma! Or any circuitry (relays Macs. etc - detals supp`edl ar:ritrucler de:a- c " - - 3 ran- can be used to switch up to 16 items of eq_ip- Used equipment - with 33 days guarantee. Manuals supplied if possible

- _ SarreS of II-- -; the merit on or off remotely. The outputs may be Trot is a VERY SMALL SAMPLE OF STOCK. SAE cr Tek,exre for Lists. Please check erefaigszy before ...:_;o.be intruder ti . s latched (to the Last received code) or momen- ordering CARRIAGE 2,7 ..,-'s £15 VAT tt be eyed to Tots,. of Goods 8 CsrUge. elsewhere_ The kit is s.:: s: compIete with tary Ion during transmission) by specifying the 7.:!.i- ..s::-.:a - 7: E 33 7 + Vs. --4-..-:E p fn. Tkes) high querty PCB. Pan a' at components decoder IC and a 15V stabilised supply is and instniff 4 - _ 'Sa mains evadable to power external circuits. STEWART OFREADING supply, = tdria The Supply: 240V AC or 15-24V DC at lOir,A. 110 WYKEHAM ROAD, READING,BERKS RG6 1PL kit even in,: _ .r.rwhich is Size feseudirig transformer) 9 x 4 x 2cnre Telephone: 0734 68041 essential to prociroe Ire ick.id sound required. The companion transmitter is the LIK18 which The "dog" Cain be adrusted to produce barks operates from a 9V PP3 battery and gives a ranging from a errs-: 4__._nand con- range of up to 60ft. Two Lyboards are tains circuitry to ; - - series of wadable ?MOM -way) and MK10 116 -way), de- balks giving a me =,.. purding on the number of outputs to be used. XK125 Complete kit of pans E21.95 MX12 IR Receiver find. transformer) £14.85 DISCO LIGHTING KITS MK18 'Transmitter £7.50 £2.00 DL1000K - Thisve:Je.for.rroney - MK9 4 -Way Keyboard 8052 -BASIC chaser features bi-directional serstrcr.ce and 1.5K10 16 -Way Keyboard . . . £5.95 E2.60 lk-Ve per channel £17.50 601 133 So= for Trans. -PA -Ter microcomputer prototyping board 0121000K -A lower cost ore -directional ver- PROPORTIONAL TEMPERA- sion of the above, Zero switching to reduce interference £9.85 TURE CONTROLLER KIT DLAII Ifar EH_ & ..r.to in- Uses "buretfire - put abowing audio 'bee: 70p technique to man - 01.3000K - 3-channe. _ -gr.: ,rz fea- thin temperature to byMATRIX Systems tures zero voltage sw;t: --7.automatic level within 0.5°C. Ideal control and budt-iner 7.--rmore.tkVY pee for photography. charnel. (1425 incubators. wine - special features include: making.etc.Mar. * powerful BASIC interpreter in the ROM of an. The 018000K is an 8 -way sequencer kit with 'odd 3kw 1240V act. Temp. range up to 90*C. Intel 8052. bait in onto -isolated sound to fight input Size 7 A s 2 5 c. -s MK4 . E7.10 whichcomes complete with a pre- * on board EPROM programmer. programmed EPROM containing EIGHTY - HOME LIGHTING KITS YES 801 different sequences including stan- Tbosekits re:essari ccr,:crer-,- * up to 255 different programmes can be dard flashing and chase routines. The KIT in- arpd fti.5u -up -Pons & are des Wed to regr:33s stored in the EPROM. chAes heinstn.dtions and all components a standard wad switch and control up to even the PCB cortnectors) and reeheres only a 300w. of fighting. * 2 RS232 ports, one for a VDU and the other boo and a control knob to corritgete. Other TDR300K Remote Control for a printer. features include manual sequence speed ad- E16.45 justment. zero voltage switching. LED mimic MK6 Transmitterforabove * 24 general au/pose ilo lamps and sound to Iglu LED and a 300 W [4.95 output per chaniret TO3001CTouchrfammer E8.50 * 8 kbytes of static CMOS RAM. And the bast thing about it is the ore: - TS300KTouthsivitch £8.50 IDEK Ectenseon kit for 2 -way * 8 kbytes of EPROM. ,a -11 ONLY £ 28.50 switchng for 1133001( E2.70 1f * on board switching regulators generate fL1 .10, -10 and 21 volts. You just reed a simple 5v supply * MATRIX prototyping space to build your own circuit. * decoded signals are provided for expanding ELECTRONICS SEND 9' x 6" SAE & 50p FOR iio and memory. CATALOGUE OR CALL AT * 116 instructions includingfloatingpoint 13 BOSTON RD. SHOP MonFri 9-5 pm arithmetic LONDON W7 3SJ Saturday 10-4 pm "The 8052AH BASIC microcontroller.. _offers an elegant and efficient way of writing TEL. 01 567 8910 control programmes for computer based projects." Ere4ctor Electronics Sept 1987. iNIIVISA IMB The MX1 board costs £250 inclusive of post and packing ORDERING INFORMATION: and £5 for just the handbook ALL PRICES EXCLUDE VAT Aft FREE P&P on orders over £20 (UK only), other.vise add 75p ÷ VAT. For full details write to MATRIX Systems Overseas P&P. Europe £2.75. Elsewhere £6.50. Send chequ&PO, 23 Grove Road. Leighton Buzzard. LU7 8SF Barclaycard'Access No. with order. Giro No. 529314002. Telephone enquiries to Peter Cox -Smith on 0234-751001 Cheques with orders payable to MATRIX Systems LOCAL AUTHORITY AND EXPORT ORDERS WELCOME GOODS BY RETURN SUBJECT TO AVAILABILITY EE December 1987

Half Price List Price 6V 16AhEasy DC -DCBreakthrough! 68000 Power Processors Sealed Batteries Converters The Signetics SCN68000C8164 is an 8MHz 68000 A sealed, maintenance free, lead acid gel bat-Measuring only 85 x 70 x 20 mm the GSR407 con- cpu in a 64pin Ceramic DIL package. Due to its tery. the EP6160 is manufactured by Elpower andverter delivers 7 Volts at 4 Amps from an inputadvanced design features the 68000 has become delivers a massive 6 volt 16Ah capacity from arange of 8-48 Volts DC. The use of modern switch -an industry standard in true 16 bit processing. A package measuring only 210 x 140 x 70 mm.mode circuitry enables an efficiency of 75% andscoop purchase enables us to offer this popular Useful for many standby or portable applications,the unit is protected against short circuit and the EP6160 is suitable for deep cycling use and isovertemperature. Simple to use, the GSR407 is of- device at the unbelievable price of chargeable from a constant voltage source.fered with data sheet, and lull application infor- P+Pmation is available. MASSIVE STOCKS +P BRAND NEW £15£3.00Brand New E 10 MUST BE CLEARED £1P SIEMENS V30141 300 WATT OPEN FRAME SUPER SAVINGS ON SWITCHMODES GRESHAM LION SWITCHMODE SWITCHMODE TRIPLE RAIL SUPPLIES A high reliability multirail supply carrying UL and CSA approvals. Built on Top quality power supplies originally manufactured for a major OEM. a rugged aluminium chassis the V30141 accepts 110 or 220Vac input and de- Three outputs on 0.156 moles connector +5V at &Amps * +12V at livers five outputs:* 5V/35A * I2V/3A *24V/3.2A *-12V/0,2A*-5V/2A 4.75AI:rips -12V at 0,5Amps Semi enclosed in an attractive black enclosure, the units are supplied All units burned in and tested. REDUCED BRAND NEW with data. Offered BRAND NEW & boxed TO CLEAR onlyE 30 _ VAT Input 240Vac on switched IEC ski only ÷ £2 p&p Overall size 390 x 225 x 70 nun. - £2 p&p E 20 DECEMBER SPECIAL OFFERS BBC DISK INTERFACE leads, 34 way speed -ELMA INSTRUMENT CASES -Supplied in kitPAPST FANS -Type 4850 120mm low noise axial bloc socket to 34 way edge connector. Availableform, these attractive and easy to assemblefans. 240V Brand New £7.00 in single or twin drive configurations. enclosures are finished in Pacific Blue and will ac-SPRITE FANS-80mm low noise axial fans high SINGLE DRIVE... £1.50 TWIN DRIVE £2.50cept either eurocards or modular components. performance. 240V NEW £6.00 UM1286 MODULATORS -HighqualityUHFSize 317 x140 x 240mrn. ONLY £10.00FADERS -Metal body construction. modulators for interface of computer and videoNEC MC5808 DBS Local Oscillator Module 10K Lin 60mm Mono £0.60 75 Ohm sources to TV sets. Data supplied.10GHz ECS frequency. 50 ohm o/p £15.00 10K Lin 45mm Mono centre stop £0.60 BARGAIN PRICE £4.00LITHIUM CELLS, Matsushita 8R2325. 3V. 23 x aram LL50 100K Lin 45mm Ster.centre stop £1.00 Semiconductors Switchmode Power Supplies GOULD MG5-20. 5V at 20A £20.00 Part No Mfr Description Price GOULD MG5-40. 511 at 40A £35.00 GOULD MG5-60. 5V at 60A £45.00 DAC80-CBI-V EtBr 12 Bit D -A Converter £4.00 GOULD MMGS-5. 5V at SA £15.00 K1135A Mote Dual Baud Rate Gen £2.00 VMS2300. 5V at 4A. 12V at 3A. -5V at IA. -12V at lA £13.00 AY -3-1270 G.I. Temperature Controller £2.00 VMS2600. 5V at 6A. 12V at 3A. -5V at 1A. -12V at IA £15.00 LD271 Siem I -Red Emitter ). 950nm £0.10 VMS2800. 5V at 6A. 12V at 6A. -5V at 1A. -12V at lA £20.00 POWER GENERAL 4100. 5V at 20A. +12V at IA. -51/ at 1A. Supplied brand BPX81-IV Siem Phototransistor8,50nm £0.10 new & boxed with data sheet £25.00 DL1416 Nat Intelligent 4 Chr Ascii Display £6.00 LAMBDA LWT-1B. SV at IA. + 12V at IGOmA. Brand new miniature FET MAB8031AH-12P Sig 8 Bit Microcontroller £3.95 switcher, size 110x 50 x 35mm. Only £15.00 LM350K Mote Adj. 3A Regulator TO3 £2.00 FARNELL N200. 5V at 30A. +12V at 5A. Few only £35.00 INS8154N Nat 16 Bit I/O + 256 Bit RAM £6.00 Other switchers always in stock. Please phone for sales or technical information on our wide range. Quantity discounts available on all the above lines. FARNELL G30. 5V at 5A. or 15V at 2A, two versions £20.00 Rechargeable Batteries Linear Power Supplies A range of YUASA maintenance free rechargeable Lead Acid batteriesELPAC SOLV 30. 12V at 4A Open frame supply. Brand new and boxed with having many applications in portable & standby situations. Suitable fordata sheets £15.00 cyclic and standby use, the sealed construction ensures long life and no ADVANCE PMG5-5. 5V at 5A £20.00 electrolyte leakage. All batteries are brand new and available ex -stock atADVANCE PMG12-1.2. +12V at 1.2A £25.00 highly competitive prices. ADVANCE PMGD15-1.2. +15V at I.2A £25.00 *6 Volt IAh £5.50*12 Volt 1.2Ah £10.00 ADVANCE PMA47. Variable 0-I5V at 3A £20.00 *6 Volt 1.2Ah £7.25*12 Volt 1_9Ah £13.00 ADVANCE PMA48. Variable 0-30V at 3A £25.00 *6 Volt 2.6Ah £8.00*12 Volt 2.6Ah £15.00 COUTANT ESM15. SV at 15k +12V at 1.5A. 12/24V at 2A 40.00 *12 Volt 6Ah £20.00 all prices + P&P CAPACITORS Motors ariF 250Vac Filmcap ACT Polycarbonate £1.00 SANYO 103-606-2 Stepper. 2 Phase 4 pole 6V 3A £10.00 100/350V Erie KB411CT £L0O 470/250V Mull 0.52 £0.80 SHINKOH 20PMA055 Stepper. 1 Phase 3 pole 28V 1.3A £10.00 2200/16V Rad. Panasonic .... £0.25 2200/63V ITT KSIOA £1.00 PHILIPS CONTROLS B82959 Stepper. 2 Phase 4 pole. 2200/200V Mallory CGS £2.00 3300/50V Maroon CGF £0.50 14Vdc Step Angle 7.5 Deg. 27.5 Ohms./Coil £10.00 4700/16V Ax.Mull 032 £0.25 4700/25V Mull 050 £0.50 KAWASAKI MC6O9R-A 6V Cassette Motor, 2400rpm £2.00 4700/63V Procond 542 £1.1010000/16V Rad Nich £0.30 MATSUSHITA MH15R2C 12V Cassette Motor+ regulator £3.00 10000/40V Lorin Computer Grade £2.00 BERGER-LAHR RDM 50/8G 12 Volt Stepper Motors. 3mm shaft. 230mA/37Q We carry a full range of Ceramic. Polyester. Polystyrene, Tantalum, Electro-per winding. Brand new stock. Only £6.00 lytic. Variable and Trimmer capacitors. DC and AC motors always in stock. Industrial Timers Bargain A range of high reliability electromechanical timers by IZUMI DENKQ All BREADBOARDS - exciting new range of solderless prom -typing boards at affordable units 240Vac and have 5A contact sets RTMSP2N-Octal base. 2 contact sets, pnces. start on power -up, power off reset. 0-6sec, 0-210sec, 0-28hr. Budget Series - 100 Tie Poirits. .11.70. 640 Tie Points...15.00. 840 Tie Points...16.50. Pre Series - 400 Tie Points...14.20. 630 Tie Poinm...17.90. 1650 Tie Points...111.80. EtTMUM2N-72trim square panel mount. Screw terminals. Specs as above. PANEL METERS, 60mm x 45mm. Cutout 38rran. Attractive Black/Clear plastic construc- 0-35sec. 0-70sec, 0-210sec, 0-7min, 0-35min, 0-210min tion. Available 50,,A, 100x.A. linA, IA, 5A. 10A. Brand new & boxed. Only.... £6.00 ea. RTMSP3B-as above but separate clutch & motor connections DRILLS - Pcb drills 12 Volt Pin chuck type...16.95. 4mm adjust chuck...0.25. Reset on Power off.0-12sec, 0-35sec-0-210sec, 0-28hr MAINS DRILLS - high power 4rnm chuck -124.75. Drill kits - 12V drill Application sheets available. All timers only £10.00 SIRENS - 12 Volt Ear Piercing 115dB output Small £9.50. Large £11.50. Ideal Car Alarms. etc. ...stop press... SOLAR PANELS FERRIC CHLORIDE -Circuit Etchant Granules. Appiox. 250g. Only...11.65/W/. - 12 ins x 12 ins. 12 Volt 200mA output in British sunlight. EEEEE WE BUY COMPONENTS FOR CASH EEEEE Bargain price BRAND NEW £15.00 + £2.00 P&P We also buy good working TEST EQUIPMENT, POWER SUPPLIES, COM- PUTER EQUIPMENT, PERIPHERALS and other hardware. Terms of business Cheque/PO with order. MailPlease note. This advertisement represents a fraction of our cur- order..phone for details ofrent stock. It would be impossible to list our vast range of elec- fuselodge Ltdp&p charges for your order.tronic components and equipment. As a broadline distributor we Callers Welcome. have comprehensive stock of semiconductors (linear,logic. 17S4 Shop Hours 9.00am to 5.30pm memory, LSI and discretes) resistors, capacitors, switches, op- 6 days a week. toelectronic products, connectors, potentiometers, fuses, cable, 267 ACTON LANE, lamps, and new products are constantly arriving. Our technical CHISWICK, LONDON W4 5DDPLEASE ADD 15% VAT TOand sales staff are always available to handle your enquiry. Telephone: 01-994 6275 ALL PRICES

THE STAFF AT FUSELODGE TAKE THE OPPORTUNITY TO WISH ALL ELEKTOR ELECTRONICS READERS AND CUSTOMERS A MERRY CHRISTMAS AND A HAPPY 1988. EE December1987

Bohm wPROM programmer Copies theEPROMs 2716...27256, 8052 -BASIC 2C-19 .. etc. as well as the corresponding CMOS-versions and EEPROMS. The RS 232 interface enables connection of MICROCONTROLLER-KIT a computer and purpose programming of the EPROMs. A 2764 for instance can I/O CONNECTIONS be programmed in 30 secs.

Bohm µPROM 2000 EPROM programmer up to 1 MBit RS232 Available askitor built and CONVERTERS tested PROM 2000 offers more possi- 7.7.014.RU / P00 ACC -*PRINTER bilities and improved simplicity and safety. DUPLEX Large memory with 8K oper- 8052 -BASIC PORT ation program. Software exten- CONTROLLER sions are possible. EPROM PROGRAMMER EPROMs and EEPROMs up to 1M8it can be programmed! Switching -on of Vcc and Vpp L voltages to the socket only at the start of the program. 32K BY 6 Automatic correction of programming voltage for each IC type by means of soft- EPROM ware or by pressing a button. For ICs with Identify Code automatic recognition and adjusting of the parameters. MEMORY RS 232 interface. Adjustable 8audrate. Hardware -reset in case of transfer failures. Fast: a 2764 is programmed in only 30 seconds! Eight function keys: "Vpp Select": for the programming voltage; "Size Select": for the size of the EPROM; Abbheeti "Mode Select": for the program algorithms; 32K BY "Reset": switches everything to zero or start position; ATA STATIC "Shift": double functions for the following keys: MEMORY "Verify": comparison of data master and IC copy; CO:ATHOL "Identify": automatic IC recognition and adjustment of parameters; "Error": prevents start. LED indication for errors; "Blankcheck": test -memory cells are "blank"; "Program": start of the programming process: "Erase": erases EEPROMs.

For further details contact CRESTBEAM LIMITED EXPANSION 8 TO 15V 389, ASPLEY LANE, NOTTINGHAM NG8 5RR CONNECTOR SUPPLY Telephone 0602 296311 FEATURES INCLUDE Pos.verful Enhanced Basic Interpreter, Universal Semiconductor Devices Ltd.

On Board EPROM Programmer, UNIT 4, SPRINGFIELD ROAD. Program Development from a VDU, CHESHAM, BUCKS. HP5 1PW 32K Bytes of CMOS Static RAM, TEL.0494791289: FAX 0494 791296 : TLX 25157 uscico g 32K Bytes of CfvlOS EPROM (expandable to 56K WE OFFER ONE OF THE LARGEST RANGES OF SEMICONDUCTORS AT HIGHLY ECON- Bytes). OMICAL PRICES. THE FOLLOWING SEMICONDUCTOR TYPESARE AVAIL- ABLE FROM STOCK. IF WE DONT STOCK WHAT YOU NEED THEN WE CAN GET IT -1,.:o RS232 Ports. FAST FROM OUR FACILITIES IN WEST GERMANY AND USA UPON REQUEST Single Unregulated Supply Requirements, TRANSISTORS - Small Physical Size (80 by 100mm), BIPOLARS - GERMANIUM AND SILICON U.S.D. WILL SMALL SIGNAL BE PLEASED Expansion with range of Compatible Circuit POWER TO HELP Boards. DARLINGTONS - ALL SHAPES AND SIZES SUPPLY SEMI- VHF/UHF DEVICES - ALL SHAPES AND SIZES CONDUCTORS FETS - POWER ArK)SFETS KIT including all components, full instructions and FOR THE UNIJUNCTIONS SATELLITE TV operating manual - £129 DIODES - GERMANIUM AND SIUCON PROJECT Manufactured and Fully Tested Circuit Board - RECTIFIERS AND BRIDGES OPTO-ELECTRONIC DEVICES £244. N -NN LEDS OF ALL SHAPES AND SIZES 04

"All prices exclude VAT. THYRISTORS TRIALS - ALL SHAPES PLEASE Packaging and Postage FREE (UK only). NOTE SIZES NEW Overseas P&P : - Europe £2.75 INTEGRATED CIRCUITS RATINGS ADDRESS Elsewhere £6.50." CONSUMER - DIGITAL/ANALOGUE MICROPROCESSORS AND PERIPHERALS IC SOCKETS c- For full details please contact JAPANESE COMPONENTS - VAST RANGE OF DISCRETES AND CONSUMER IC's. 1988 CATALOGUE IN PRODUCTION - NEW CUSTOMERS PLEASE ENQUIRE AT OUR SALES DESK. TEL 01 348 9420, FOR PRICE AND DELIVERY OF COMPONENTS

SPECIAL DISCOUNTS AND PAYMENT TERMS ARE AVAILABLE TO OEM'S. inQ n I 1) electronics ltd SCHOOLS. COLLEGES, UNIVERSITIES, GOVERNMENT INSTITUTIONS. COMPUTER FIRMS, ELECTRONIC REPAIR RAMS AND DISTRIBUTORS.

PLEASE ENQUIRE FOR QUANTITY DISCOUNTS. MONIFIETH BUSINESS CENTRE WE WELCOME TELEPHONE AND TELEX ENQUIRIES! DUNDEE DD5 413jTelephone: 0382 534944 112EE December 1987 REGULATION AND LIBERALIZATION

A Wolters Kluwer Company Managing Editor: Len Seymour The recent seminar at 10 Downing Street on the future of British broad- Personal Assistant: L. Vousden casting highlighted once again that there is no one view on the need for Technical Editor: J Buiting regulation, although there seems to be a general concensus that a great Advertisement manager: S Brooks many of the existing regulations are outdated and unrelated to today's Editorial offices: 1 Harlequin Avenue needs. Great West Road BRENTFORD On the one hand, there is a strong lobby that wants the Government to Middlesex TW8 9EW England abide by the popular demand for consumer sovereignty, while on the Telephone: 01-847 2618 other, there are many who want it to make sure that viewers and listeners Telex: 917490 (elektr g) can not watch, or listen to, programmes that in their opinion is unduly full of European offices: sex or violence. This presents a serious dilemma, of course, because the Postbus 75 vast majority of television viewers, for example, would rather watch Rambo 6190 AB BEEK IL) The Netherlands II or Sex Kittens on the Loose than Triumph of the West or The Great Telephone: +31 4402 89444 Philosophers. Telex: 56617 (elekt nil Fax: +31 4402 70161 But the problems do not end there. In their deliberations over the white Overseas editions: paper on the future of broadcasting, the Government will have to Publitron Publicacoes Tecnicas Ltda Av 1piranga 1100, 9° andar recognize that the quality of programmes received in this country can in CEP 01040 Sao Paulo - Brazil future no longer be controlled solely by the BBC, the IBA, or British regu- Editor: Juliano Barsali lations. That requires agreement among broadcasters and advertisers in Elektor sari many other countries, particularly Europe and the United States. Un- Route Nationale; 12 Seau; B.P. 53 59270 Bailleul - France doubtedly, not all of these see the purposes of broadcasting in the same Editors: D R S Meyer; light. G C P Raedersdorf Elektor Verlag GmbH Fortunately, a commission appointed by the European Institute for the Silsterfeld-Stralle 25 Media and the European Cultural Foundation is already engaged on find- 5100 Aachen - West Germany Editor: E J A Krempelsauer ing ways to unify the views of at least those in Europe concerned with programme making. Elektor EPE Karaiskaki 14 16673 Voula - Athens - Greece Similar problems abound in the world of telecommunications. Like the tele- Editor: E Xanthoulis vision viewer or radio listener, the telecommunication user will judge the Elektor Electronics PVT Ltd. aptness of regulations by their obtrusiveness. Unlike the television viewer, Chhotani Building who may simply see certain regulations as an infringement of his personal 52 C. Proctor Road, Grant Road (E) Bombay 400 007 - India freedom, the telecommunication user is likely to be a business man, who Editor: Surendra lyer may consider some regulations as constraints, preventing him from carrying Elektuur B.V. out his business as he feels the should. Peter Treckpoelstraat 2-4 6191 VK Beek - the Netherlands Unfortunately, and this is an old problem in telecommunications, national Editor: P E L Kersemakers regulations often can not be adopted internationally. Itis, of course, right Ferreira & Bento Lda. that countries can, and should, decide for themselves what their national R.D. Estefania, 32-1° 1000 Lisboa - Portugal regulations should be. But it is to be hoped that in formulating new regu- Editor: Jorge Gonsalves lations, countries in this day and age will take into account the situation in Ingelek S.A. other countries. Fortunately, there is an intergovernmental organization, the Plaza Rept%lica Ecuador International Telecommunication Union-ITU-that provides the regulatory 2-28016 Madrid - Spain framework for trans -frontier telecommunications structures. Editor: A M Ferrer Electronic Press AB In the interest and furtherance of individual freedom, the overriding im- Box 63 182 11 Danderyd - Sweden portance of consumer sovereignty must be emphasized. Regulations are Editor: Bill Cedrum necessary, but they must not have the effect of restricting the consumer's International co-ordinating choice. A proper balance needs to be sought, and maintained, between & technical manager: regulation and liberalization that will be in the interest of everybody. K S M Walraven International editorial secretariat: G W P v Linden; M Pardo The past year has-been one of recovery and subsequent stabilization for Distribution: Elektor Electronics after its divorce from Glentop. During the year, we had Seymour Press Ltd., 334 Brixton the great misfortune to lose, through his unexpected death, our Info/Data Road, London SINS 7AG. card Editor. This has meant the (hopefully temporary) suspension of our In- Typeset & composed in the fo/Data card service. This will probably be resurrected soon, but in a rather Netherlands by GBS, Beek IL). different form. Printed in the Netherlands by NDB. Zoeterwoude. The subscription service, which on occasion has been (rightly) criticized, is now being handled by World Wide Subscription Service Ltd, which will Copyright 1987 Elektuur B.V. mean a much prompter response to subscribers' queries. ABC We thank all our readers for their continued support and wish you all A Prosperous and Peaceful New Year! kEVEIR or OLE FI;ot RE.F.0 OF COO JI.ATOFS EE-El D...... ::r -=' 7',--2":37 ELECTRONICS NEWS ELECTRONICS

GEC endowment for representing an infra -red pixel specialreport to AFDEC available according to market London University canbeelectronicallyad- members. They are based ondemand. Recently opened new elec-dressedandactivated in- information supplied by Furtherdetails on the Cor- dependently of its neighbours. tronicsengineeringlabora- members and other reliable climatic 7000 from C.E. A resistor's temperature can be toriesatUniversityCollege, sources and represent an en-Johansson Ltd 66 High Street

increased by a maximum ofcouragingimprovement London. were a gift from the on Houghton Regis 25 CC above the nominal General Electric Company. The 1985-86 figures, which showedDUNSTABLE LUS SBJ Tele- baseline operating temperature laboratories will provide an overall decline of 4-5 per phone (0582) 867711. greater opportunitiesfor ad-of the device. cent from those of the previous vanced research into communi-The degree of heat emitted by a year. resistor depends upon the cur- cations,microprocessor, and The document is priced at £225 rent flowing through it and this space technology. plus VAT, to include quarterly Westinghouse Cubic can be programmed to be one updates, and is available from just the ticket

of 200 values so providing a AFDEC Owless Hall New 'Quickfare'automatic graduated range of tempera- Owles Lane BUN- ticket machine from ture colours for the generation TINGFORD SG9 9PL. Westinghouse Cubic, now Ferranti merges with of high -resolution infra -red im- undergoing trialsat London ages. The substrate also func- ISC Bridge Station,are speeding tions as a heat sink. It forms the Ferranti, the Manchester -based base of a chamber containing a pasengers to40BritishRail destinations in south and south- electronics giant, has merged fluorinated hydro -carbon liquid with International Signal and and is cooled by the latent heat east London, as well asto stationsinKent and Surrey. ControlofLancaster,Penn- of vaporization of the liquid as it Westinghouse Cubic, the auto- sylvania. The new company has boils.Thisarrangement en- aworldwideturnoverap- sures the thermal response of maticfare collectionand proaching £1 billion, and will the resistors is sufficiently rapid revenue systems specialist, is jointly owned by Hawker Sid- be particularly active in the for dynamic infra -red images to denly and Cubic Corporation. world's defence, space, and in- be produced in real time by the John Walker (left), Chairman of dustrial electronics markets. thermal picture synthesizer at AFDEC, and Christopher Since their installation last June, frame rates of up to 50 per sec- Sawyer, Deputy Chairman of the two custom-built machines, ond. AFDEC. strategically placed at the main barrier next to the ticket office, have recorded a total of over Thermal picture 40,000 ticket sales. A variety of synthesizer Co-ordinate ticket combinations are A solid-state thermal picture measuring machine available to travellers from the automatic machines. Each synthesizer has been devel-Continuing growth in A co-ordinate measuring component sales machinehasanelectronic oped by British Aerospace. It machine, which has absolute clock capable of calculating consists of a matrix of thermally - The Association of Franchised measurement scales in all three off-peakperiods,weekends, emitting thin-film resistorsDistributors of Electronic axes and uses UNIX -based soft- bank holidays, and even leap deposited on a thermal insu- ware, has been introduced by Components-AFDEC-whose years. lation layer built on a siliconmembers account for a half of the Swedish quality assurance substrate. The substrate con- the distributors' share of total specialists C.E. Johansson. tains a corresponding matrix ofUK sales of electronic compo- Initially, customers can specify integrated -circuit diodes usednents, forecasts an overall UK delivery with either IBM or in the control of the resistor market growth of 9% to £1,577 Hewlett-Packard computer matrix. The image area of the million for these products dur- systems, but the manufacturer device is 35 mm2 and containsing 1987, and a futher 11% to intends to make other systems 10,000 resistors arranged in a £1,746millionin 1988.The 100 x100 matrix. Each resistorforecasts are contained in a 11:1EE December 1987 ELECTRONICS NEWS ELECTRONICSNI

Bumper ELECTREX in the medical training market. THE WEST EUROPEAN TRANSDUCER MARKET again Video disctechnologyalso makes possible interactive pro- BY MAJOR COUNTRY - 1987 ELECTREX '88, Britain's major grammes that can accept user international electricaland input and respond to that input. electronicsexhibition, pro- According to The Non - mises yet again to be anotherconsumer Market for bumper show: to date more Videodisc Technology than 1,000 companies will be (4A1665),a report from Frost & represented on 485 stands oc- Sullivan, sales of non -consumer cupyingover24,000 mz of video disc programmes will space. The exhibition will be rise in value from an estimated held at the NEC, Birmingham, $140 million in1987 to some from 29 February to 4 March £606 million by 1991. Although 1988. the report is cautious about the TOTAL S525M ELECTREC '88 will be visited future of non -consumer video by an inward mission of about Sant; ,:ut t disc technology, it makes clear Frx,-: nice 20 top level potential buyersthat this is a technology with from selected markets aroundconsiderable potential, which the world, each of whom has £4.1 billion between 1987 and support to the new international may be realized sooner than 1992. The study covers any Components in Electronics ex- purchasing influence in their many analysts think. particular sphere. The mission device that couples a sensingposition to be held in London is being organized for ELEC- element for pressure, tempera- from 8 to 10 March 1988. TREX by BEAMA with financial ture, flow, level, motion, etc. to The show has further received assistancefromtheBritish an output element that gener- a boost with the news that Nor- Overseas Trade Board. ates an electronicsignal.It man Merritt, Manager of the Cossor IFF for Abu deals with more than 25 types of MOD's Electronic Component Dhabi transducer and says that the Standardization Scheme, and an CossorElectronicshasre- prospects for many of these internationally highly received an order to supply four hinge on the accelerating trend spected figure in the area of New future for video Identification Friend or Foe- toward the integration of micro- component quality, has agreed discs IFF-systems, which will be in-processor technology into in-to become Chairman of the Video disc players marchedstalled in patrol vessels beingstrumentation and device de- Conference Programme Man- sign. into the consumer markets inbuiltfor Abu Dhabi by the agement and Papers Vetting available from 1978 with much fanfare, only to German shipbuilders, Lurssen.The report is Committee. Frost & Sullivan Ltd Sullivan limp out again a few years later The total value of the installed Further information from Nut - House 4 Grosvenor Gardens in defeat: they were no match systems exceeds £0.5 million. wood Exhibitions Ltd Guar- LONDON SW1W ODH. for the cheaper video cassette The order is the first for the new dian House Borough Road recorders. Type 850/4 system which incor- GODALMING GUI 2 AE But video disc technology has porates the Mark XII compat- Telephone (04868) 25891. some definite advantages over ible cryptographic capability. video tapes,particularlyfor training applications in the non - AFDEC support for consumer industrial,govern- new show ment, professional, and com-The transducer AFDEC, the electronic compo- mercialmarkets.High -resol- market in Europe nent distributors'association. ution,high -qualityvisual im-A Frost & Sullivananalysis ages give video disc program-suggests that the transducer has agreed to officially lend its mes a long leg up, for instance, market in Europe will amount to

NON CONSUMER MARKET FOR VIDEODISC TECHNOLOGY - PLAYER & DISK SALES

1987 1988 1989 1990 1991 Tent t 541141s. nrc. it=ft 01143 EP December 19E7 ELECTRONICS NEWS ELECTRONICS

£650,000 for the flat TV screen. However, the companiestohold capacitySelection of freely definable Hatfield Polytechnic report entitled Flat Panel Dis-available to execute them in data transmission allows for op- play Market in Europe (#E961), due course," he says. eration in NRZ, MANCHESTER The Department of Trade & In- predicts that this will not be"Our industry is a wonderful (RZ), FFSK. PSK, DPSKO, DPSKI, dustry has announced that Hat- achieved before 1992. Instead,opportunity for wealth creation field Polytechnic is to receive FSK, Biphase mark and Biphase products such as portable com-and, in order to achieve our space over £650,000 in two separate transmission modes. puters and car dashboards will maximumpotential,we do User -defined transmissions can projects. The first is to set up an incorporate the technologiesneed Governmentpoliciesbe programmed and recorded "awareness and training" well before that date. which willgiveus greater in non-volatile memory. centre at Hatfield for Advanced The report predicts thatflat possibilities for increasing our Manufacturing in Electronics, paneldisplayswillbrightenthroughput in this country as a and the second to support ac- from a $399 million market inbase from which to expand our tivities by Cimtech, the Europe in 1986 to in excess ofexport activities." polytechnic's National Centre $1.3 billion in 1992. Most of the The key role of Government in forInformationMediaand speed in this stems from the the affairs of industry is stressed Technology. automotive industry which willin the report by BEAMA's Di- Similar Advanced Manufactur- rev up itspurchases offlat rectorGeneral, Mr Gordon inginElectronics(AMIE) panel displays by more thanGaddes. The year had seen centres are being created in a 64% a year. LCDs, which have further emphasis on the case number of other polytechnics costadvantagesoverother for more investment in the elec- anduniversities throughout types,and thin-filmelec- trotechnical infrastructure. Britain.Initially,sixcentres troluminescent ones, desirableThe British electrotechnical in- The 4922 incorporates an IEEE - were to be funded, but because because of their solid-state con- dustry in 1986 had a total pro-488 interface as standard to of strong demand it was decid- struction, will dominate as theduction of £25,953 million, of followfor use in automated ed to set up 12 over two years. auto market matures. which £10,408 million, or 43.5 systems and output of signalling The funding going to each will per cent, were exports. The results to a printer. cover 50% of costs over the in- 1985 revisedfigureswere Further information from Solar- itial two-year period, says the £23,526 million, of which £10,336 tron Instruments Victoria DTI. million or 43.9 per cent, were Road FARNBOROUGH The Hatfield centre will cover Winning overseas exports. GU14 7PW Telephone (0252) virtually the whole of south- Production in those product 544433. easternEngland. Thepoly- power station orders extremely competitivegroupscomingwithinthe technic has a wellknown track BEAMA scope(thatis,ex- record in the field of elec- In his report for1986-87, Sircluding such items as com- tronics and industrial systems William Barlow, the President of puters and consumer durables) and control. BEAMA, the federation of 17accounted for £13,083 million Fluke & Hilevel Further information from Hat- manufacturers' trade associa- (1985 revised: £12,788 million), of Technology alliance tions,says field Polytechnic College thatBritain'sin- which 38.9 per cent (39%), or John Fluke Manufacturing Lane HATFIELD AL1O 9AB. dustrialelectrical and elec-£5,085 million (£4,991 million), Company Inc. of Everett, tronics industry is having to winwere exports. Washington, and Hilevel Tech- power station orders overseas Imports in the BEAMA sectors nology Inc. of Irvine, California, under extremely competitive were £4,577 million (1985: £4,472 have signed a letter of intent to situations. million),giving a favourable form a strategic alliance be- Flat panel display Sir William looks forward tobalance of trade of £508 million tween the two firms. early announcements of CEGB market in Europe (519 million). Under theproposals,Fluke orders for coal-fired power sta- would purchase about 25 per The major driving force, ac- tions. "Every month of delay in cent of Hilevel for about $6 cording to an analysis by Frost the placing of orders makes it million, providing the Califor- & Sullivan, has been the goal of increasingly difficult for nian firm with added capital for Radio Code Analyser expansion. In turn, Fluke would FLAT PANEL DISPLAY MARKET IN EUROPE Solartron's Type 4922 Radio be granted licences to use tech- BY END -USER - 1986 Code Analyser provides all the nology developed by Hilevel in test facilities required by the non -competing applications. expanding pager market. It isFluke is a leading maker and Wsv, I Aecsawe designed for production and marketerofelectronictest, repair environments, but is also measurement, and control a valuable tool in development. equipment. Hilevel Technology As well as performing selective has a growing leadership pos- call, cellular, and DTMF system ition in ASIC verification testing, the unit incorporates systems and ASIC applications

C.sr...,ro +cu.can tat .1U generation facilities for testing support. bleepers, numeric pagers, and message masters using POC- tat I Sall ton. Nc. %pan 4.3161 SAG, and generation/analysis facilities for FMS, ZVEI Binary, anduser -definedsignalling systems. EE December 1987 TELECOMMUNICATIONS NEWS TELEC1

UK start for new cable to span the Atlantic be-of specialized antennas andVAN services in Atlantic link tween Europe and the United fibre optics. Europe States.Itscapacityisthree Work in Britain on laying the times greater than that of all the A recent report from Frost & world's first transatlanctic op- others together. Sullivan, Value-added Network tical fibre cable-code-named The new cable will form an im-New hi -tech facility Services in Europe (#E940), TAT8-has started.At Wide - portant part of a new globalfor Cincinnati predicts that the VAM market mouth Bay in Cornwall, the UK will be rising about 40% a year communications network, shore end of this £220 million Electronics asanaveragecompound whichwilloffercustomers undersea system is being in- Cincinnati Electronics, the growth rate, from $900 million in fasterconnections,andim- stalled bystafffromBritish world's leading developer of 1986 to almost S4.9 billion by proved quality links at lowermanpack transceivers, has Telecom International. cost. A whole range of ad- 1991. The greatest gains are ex- The shore end of the cable will opened a new high-tech facility ditional services will be made pected to come in the period befloatedashorefroma inMason,Ohio. Theultra- possible with the new digital 1988-90, when the compound cableship, secured, and sunk modern structure will house growthrate isforecastto links. intoposition by divers. The Cincinnati Electronics' growing average 57%. A second transatlantic opticalAerospace Division. About half cableship will then move off to fibre cable is being planned to As might be expected, lay the remainder of the first the93,000squarefeetof business users of VANs, which comeintoservicein 1991. 12 km of the UK section of the floorspace is dedicated to eight range from data bases, elec- Called TAT9, the $400 million highlysophisticatedlabora- cable. system will have landing points tronic mailservices, and Next spring, the main 520 km tories specifically designed for in Britain, France, Spain, videotex to paging services, ac- UK section of TAT8 will be laid advanced -technology research count for more than 80% of the Canada. and the United States.and development work. by BTI's cableship CS Alert. The cable's main transatlantic volume generated ($726 million She will carry out the laying section will have the capacity to in 1986). with the aid of BTI's remotely- The reportexplores the carry 75,000 simultaneous controlled plough, which will phone calls. nationalmarketsofFederal bury the cable beneath the The new cables will help British Germany, Britain, France, Italy, seabedtoprotectitfrom Telecom to meet the continuing and Scandinavia in detail, and damage by ships' anchors and growth of the number of tran- also develops figures for the trawling. satlantic phone calls, which has rest of Europe as a whole. The UK section of the cable will been doubling every five years. As shown in the figure, the UK be connected by afurther the largest VAN market, ac- 20 krn link to a special junction counting for some 35% of the Cincinnati Electronics Corpor- device on theoceanfloor, European total (£220 million in ation has been active in military 540 km south of Widemouth 1986). France's FF1.5 billion in and commercial electronics for Bay. This will join the UK cable 1986 ranks it second, accoun- British Aerospace, over 60 years. Business areas in- to a similar section from France, ting for about a quarter of the clude tactical communication connecting both to the main Marconi, and STC European volume. Both these 5,000 km span of the cable to jointly pursue new systems and equipment, elec- countries, however, will lose in the USA. submarine communi- tronic warfare systems, space share duetofastergrowth When TAT8 comes into service cations package electronics, infra -red systems, elsewhere, such as in Federal next summer, it will have the radar, and contract manufactur- Germany, which in1986 ac- British Aerospace, Marconi ing. Their Aerospace Division potential capacity to carry the Radio Systems, and STC have counted for only 12%, or DM220 equivalentof40,000simul- istheleading producer of million, of the European formed a team to jointly tender rangesafetyreceiversfor taneoustelephonecalls,or for the communications system market. their equivalent in data, text, space launch vehicles, which of the Royal Navy's next gener- have been on board 75% of all facsimile, graphics, or TV pic- ation of submarines. tures. US launch missions in the past The direct capability and ex- five years. TAT8 is the eighth telephonepertise of this combination is formidable. For the first time, a single organization will have the effective expertise to ad- THE MARKET FOR VANS IN EUROPE dress all aspects of naval com- BY COUNTRY - 1986 munications. Theindividualstrengthsof each company are complemen- Italy S36.6M W. Germany $109.1M taryandincludeMarconi's France 5224.6M breadth of involvement in naval communications through pro- What is claimed to be the duts such as ICS3 and SCOT; smallest, most cost-effective British Aerospace's back- CTCSS encode only panel has ground innaval procedures been designed, and is now and programmes such as the Others S126M manufactured, by Communi- U.K $314M cations Development Specialists shipborne SAMHADs and DIMPs data handling systems, ,:11t . Itc. Ltd P.O. BOx 83 114: BASINGSTOKE RG25 2PX andwith STCprovidinga Scandinavia 590M Telephone 10256) 83528. valuable capability in the area EE December 1987

TELECOMMUNICATIONS NEWS TELECi

GEC -Plessey Cable & Wireless PLC, has ap- From these, the risk of locust in- Marconi upgrades to Telecomms merger pointed Vanderhoff Businessfestation can be assessed, sostandard 'A' for Systems to be the first that effective counter measures Negotiations are proceeding on distributor for the Mercury 2200 tnay be taken if and where re-Mercury the proposed merger of the telephone service. This uses aquired. TheSatelliteCommunication telecommunicationsbusiness Smart Box to connect customers Itis hoped that the satellite Department of Marconi Radar of General Electric Company to the Mercury network. systemwillpreventrecur-Systems has just completed a and Plessey. The aim of the new The Mercury Smart Box is in-rences of the plagues of the contract for Mercury Communi- company isto offer a more stalled on the exchange side ofpast,notably thatof1974-75 cations which providesthat powerful and competitive customers' PABX equipment. Its when a large part of the totalcompany with itsfirst Intelsat rangeof telephone systems purposeistowork tothe grain crop in the Sahelian zoneStandard 'A' earth station. worldwide. customer's advantage in was lost. (The Sahelian zone is The work involvedtheup- Although GEC's turnover deciding when a call can bethe vast strip of land between grading of an existing Marconi (£5.939 million) is vastly greater more economically handled bythe Sahara and the savanna 13 metre antenna-which was than thatof Plessey (£1,430), Mercury and automatically rou-reaions from the Red Sea to the previously operating as a Stan- their telecommunications turn- teing it accordingly. Mercury Atlantic). dard B-through the use of overs do not differ much-GEC: 2200 customers benefit from readilyavailableparametric £749 in 1986; Plessey: £681 in call cost savings of an average low -noise amplifiers to become 1986.Both companies were, of 15% on long-distance con- the first antenna in the world of therefore, at pains to stress that nections and itemized billing at its size to meet the new Stan- they would haveanequal no extra charge. dard 'A' Specification since its number of directors on the Land -mobile satellite Inadditiontothe Mercurycommunications revision by Intelsat. board to the new organization. Smart Box, Vanderhoff are also Remarkably, the antenna meets Although the Monopolies and national distributors for Mer- INMARSAT andtheCentre the required G/T of 35 dB/K Mergers Commission last year cury Paging and are undertak-National d'Etudes des down to 14° elevation; no mean rejected GEC's bid for Plessey, ing the billing of air time to Telecommunications (CNET) feat considering the antenna's it is reported to be strongly in subscribers. have conducted a series of suc- physical location in the bowl of favourofthetelecommuni- Further information from cessfultrialsinvolvingthe what was previously a quarry. cations merger. Vanderhoff Business Systemsreception of messages trans- The entire exercise was made The telecommunications Ltd 19 Station Approach mitted to a moving vehicle via possible only because of the market in Britain is worth about FLEET GUIS 8QY. satellite. advanced RFdesigntech- £1.6 billion, of which GEC and The compact trials equipment niques used by Marconi on its Plessey together takeabout was identical to that which will antennas.Marconiisworld half. It is expected that the new be used for maritime communi- leader in the synthesis of the company would be predomi- cations applications when main and sub -reflector profiles nant in Britain in the markets for Locust alert by satellite INMARSAT introduces its Stan- ofcassegrainantennas.To multiplexing equipment, micro- dard -C service next year.It achieve this lead, a variety of wave radio, optical transmission The United Nations, the EEC,consists of an electronics unitsoftware packages has been systems, PABX equipment, as and the United States have paidmeasuring 73 x 214 x 279 mm developed which provides the well as having more than a third for a satellite system, now near-and a conical antenna with a basic design tools. These proof the telephones market. ingcompletion,thatisde- diameter of 190 mm. The two grammes are based on a rigor- signed to avert future locustunits together weigh less than ous vector implementation of plagues and thereby protect 4 kg. Standard -C is a data -only physical optics, and form the the crops in the locust belt ofonly system which permits the core of Marconi's design tech- Asia and Africa. transmission of test messages at nique known as Diffraction Pro- Mercury service Sensors on the satellites will through Vanderhoff a rate of 600 bits/s. Mobile users fileSynthesis-DPS.Practical give information from whichare connected via satellite to comparisons have shown this Mercury Communications Ltd,maps can be produced thatthe standard telex and other technique to have a significant a wholly owned subsidiary ofshow vegetation and rainfall. data transmission networks. advantage over classical design Measurements taken on motor- tools based on the Geometrical ways, secondary routes, moun- Theory of Diffraction-Gm tainous routes, and incities DPS-unique to Marconi- fromCalaistotheSpanish allows an interactive design of border yielded very encourag- optimum surface profiles to be ing initial results. On the motor- achieved from a given primary way or open road, for example, feed system, which inturn the percentage of messages re- allowsreflectorsystemef- ceived correctly the first time ficiencies (including the effects was higher than 96%. Because of main and sub -reflector spill- messages are retransmitted un- over,sub -reflectorblockage, til received, the reception of a and non -uniform phase in the givenmessageisvirtually aperture fields) of up to 95% to guaranteed.Obstacles like be achieved. bridges, electrical power lines, and trees caused practically no degradation of reception. 19 EE December 1987 301VIPUTER NEWS COMPUTER NEWS

The report cites four major Local Area reasons for the pace of LAN COMPUTER LEASE/RENTAL Networks in growth in western Europe: the MARKET IN EUROPE - 1986 price of the technology will Europe continue falling; the need for data sharing will intensify; con- The United Kingdom's early sensus on technical operating Sales (new) 617862M lead in computers has given it standards is arriving, bit by bit; the edge in creating networks and LANs help control office in the workplace, but by 1990 cabling costs. bothFederalGermany and Frost & Sullivan Ltd France may eclipse the UK in Sullivan House Used Equipment 91245M what will be a $466 million a 4 Grosvenor Gardens Rental(new)$1013M year market to link machines LONDON SW1W ODH together. SOU,CE, Tr.,. 1 5,1111 -se,is Local Area Networks in Europe Lease (new) $9107M (#E857), a 307 -page Frost & Sullivan report, says that the im- Computer petus to link computer -related LOCAL AREA NETWORKS IN EUROPE lease/rental in INSTALLED BASE - 1986 devices to each other is so great that the 298,000 nodes in place Europe in Europe at the end of 1986 will are being eradicated. which exceeds the EEC's local quadruple by 1990, approach- Close tohalf the new com-Leasing will become the domi- sourcing requirement-with a ing an installed base of1.4 puter business generated in nant form of computer acquisi- planned increase once pro- billion. Europe by 1991 will stem from tion in the UK by 1990: that year, duction is under way. There is a relatively higher in- lease arrangements, according close to $2.9 billion worth of stalled base in the UK and this to Computer &Communi- computers will be leased. but will tend to reduce the uptake cations Lease/Rental in Europe only S2.8 billion sold new. of new systems. In 1986, though, (#E951), a study from Frost & Frost & Sullivan Ltd New the UK represented nearly 30% Sullivan. It predicts that half the Sullivan House ($69 million) of European LAN $55 billion annual computer/ 4 Grosvenor Gardens architecture for shipments by value. There is a telecommunicationsgearin- LONDON SW1W ODH disproportionally low installed vestment then will be in equip- graphic base in Federal Germany. Cor-ment that the end user does not porate business there is move- own. systems from ing away from central main- Leasing is of particular benefit Brother moves Fairchild frame computers towards more in a field such as computers, en- distributed processing-abling the user to update to the printer factory Fairchild Semiconductor Cor- creating extremely strong sales latest equipment without theto UK poration recently disclosed a that will account for well over a difficulty of disposing of exist- new architecture for graphic quarter of Europe's 1990 ship- ing equipment, the report says. Brother printers are now being systems. The architecture ments. Furthermore. a lease arrange- made in Britain. The decision to (patent pending) willsignifi- The strongly centralized organ- ment enables a firm to acquiretransfer production from Japan cantly improve theperform- ization of French business and an asset without a large capitalto Wrexham (where operations ance of graphic systems by in-

government and lack of strongoutlay, only incurring regular,started on 1 October) follows creasing vector performance of support of LAN products bybudgeted operating expense. thesuccessofestablishinglow-cost systems by 10 times, distributors and dealers are fac- Of course, tax authorities are typewriter and microwave oven and doubling or trebling the tors in France's low share of the not blind to this situation, andproduction plants in Wrexham performance for polgygon, bit- LAN market. many of these fiscal advantages over the past two yearsto blt, and characters. The new ar- supply EEC markets. chitecture is expected to have a LOCAL AREA NETWORKS IN EUROPE A complete range of dot matrix significantinfluence on new INSTALLED BASE - 1986 printers will be produced, start- workstations and PC add-on ing with the company's popular designs reaching the market in 1709-a wide carriaae model 1988. that is compatible with all com- The revolutionary achitecture is puters and suited to a variety of based on a unique, low-cost im- business applications. plementation of multi -cellular With an average planned pro- framebuffers. The perform- duction rate of 3,000 printers ance level available with Fair- per month, rising to a projected child's patented architecture is 10,000 per month, it is estimated 10 times. This architecture will that around 100 jobs will be allow an upward growth path in created locally by the time full graphicsfrom2 -dimensional productionisachieved next with limited 3 -dimensional year. In addition. over 50 per capability,toa full-blown 3 - ICIOCE. S.:11We, It, dimensional system. .asortFEES: Scandinavia 17,000 cent of all printer components Italy 21.500 are to be supplied locally- EE 19S7 OIVIPUTER NEWS COMPUTER NEWS

Changes in IT Managing Director of Amstrad Espana SA, and Ms Marion Van- industry nier, Chief Executive of Amstrad International SA, are According toa report from appointed to the main board of Diebold, the US computer con- Amstrad PLC. sultancy firm, the IT industry will undergo vast changes in the years leading up to the 21st century. The report says that today's methods cannot cope with the fast changes and that new ones are needed. Amstrad in Many medium -size companies Spain will disappear, either through bankruptcy or by being Amstrad recently announced swallowed up by bigger ones. that it has agreed to acquire the Such companies will find that total shareholding in In- they are neither big enough to directly transferred to the target distributor. Mr Sugar was, how- descomp SA, theSpanish compete with the giants, such application thus reducing ever, at great pains to explaincompany responsible for the as IBM, AT&T, and Apple, nor valuable engineering time. that the USA "is also a very distributionof Amstrad PLC havetheytheflexibilityof Cambridge Microprocessordangerous market; we have products in that country, sub- smaller concerns. Systems Ltd always expressed caution with jecttothe approval of the The report sees the structure of Brookfield Business Centre respect to this territory and will Spanish General Directorate of the IT industry, which com- Twentypence Road continue to do so. The USA will Foreign Transactions. prises computer, office auto- Cottenham not be allowed to drain our Amstrad will pay a total price of mation, andtelecommuni- CAMBRIDGE CB4 4PS resources. None the less, no ef- £21.65millionconsistingof cations producers, consisting fort will be spared to ensure 8,812,518 ordinary shares with by the end of the century of a success and I will take a per-the balance in cash. small number of giantpro- sonal interest in the develop- Indescomp SA, which has been ducers and a large number of ment of this market". Amstrad's exclusive small entrepreneurial firms. Amstrad reports InFrance, AmstradInter- in the Spanish market for the The study feels that the giants national SA has traded very well pastthreeyears,andhas have the enormous advantages record sales in its home market, where there devoted itself solely to the dis- of low-cost manufacturing, is an excellent nation-wide dis- tributionandmarketingof high -volume output, worldwide In his statement to the annualtribution network in place for Amstrad PLC products, earned presence,politicalinfluence, report for the twelve months en-all Amstrad products. profits before tax for the half credibility, and financial ding 30 June1987, Mr AlanThat sales and marketing suc- year ending 30 June 1987 of £1.9 resources. Sugar, Amstrad'schairman, cessiswellrewardedby million and had net assets of reported record sales of £512Amstrad is shown by the an-£5.1 million. On completion of million,an increaseof 68% nouncement that both Mr Josethe transaction, it will change compared with last year's sales, Lois Dominguez, the founder of its name to Amstrad Espana SA. and record pre-tax profits ofIndescompand now the £135.7 million, an increase on Half height VME last year of 80%. The report comes just a week processor after the launch of the new word-processing computer, the PSI Systems of Cambridge haveType PCW9256, and just a day announced a new half height aftertheannouncementof VME 68000 single board com-Amstrad'sacquisitionofIn- puter. The card is British made descomp SA. The PCW9256, and is ideally suitable for targetsuccessor to the PCW8256, has applications or as the systema better printer, larger disc processor of a VME develop-storage, and improved word- ment system. processingsoftwarewitha Thecardispackedwith spelling checker. The screen features which allow it to benow displays black characters used as part of a 68000 develop- on a white background. ment system, and intarget Amstrad is clearly the market systems ranging from single -leader in the UK, but it has also board controllers to complexmade tremendous inroads into multi -tasking and multi- a number of European markets. processor control systems. A Equipment that enables personal computers to be used as telex In Italy, it has recently formed terminals is now available from the Swedish firm ITD-Wernor. Called major advantage of thisap- Amstrad SpA, which started PcTex, it consists of a printer with built-in telex functions and soft- proachis thatexperience trading last month. In the USA it ware for the IBM PC and compatibles. Further information from ITD- gained in development can be hasrecentlyacquired its Wernor AB Box 1050 S-171 21 SOLNA Sweden EE December 1987 LETTERS LETTERS LETTERS

Sir-In your admirable tribute and I feel that I must write to above matters, and also show better sounding design. The to Alan Turing (EE, October, you in protest: stop publishing me that I have not wasted my valve preamplifier is intended 1987) you say that Turing's work misleading information! time in writing to you. for dyed-in-the-wool valve en- laid the foundations for modern With reference to the article en- In conclusion, I am quite sure thusiasts. Ed. computer science. Be that as it titled Active phase -linear cross- that the original authors of both may, the Science Museum is at over networks (EE, September, articlesareawareoftheir present trying to find an answer 1987), it is implied both in the mistakes, but it would be no dif- to the question as to whether text and by the diagram in Fig. 2 ficult task for me (or many other Sir-There has been much talk, CharlesBabbage (1792-1871) that the vertical polar diagram people, for that matter) to fur- and even more writing, over the succeeded in designing the of the so-called phase -linear nish you or your readers withpast 12 months or so as to big- world's first computer during cross -over network shown isadequate proof of their most ger and faster microprocessors. the middle of the nineteenthmuch broader in the regionbasic errors. It is my, and many other chip century-just about 100 yearswhere two loudspeaker units designers', belief that the re- before the work at Bletchley radiate equally. This is absolute C.W. Pollard cently introduced 32 -bit chips Park. nonsense! The verticalradi- Wellingborough will control the computer world Babbage's Analytical Engine is ationpatternoftwounits Northants for the next decade, perhaps thought by many to be the first radiating equally and in phase even into the next century. The design of a computer. The giant isa function of the relativeAs regards the article by T world does not (yet) need a big- machine, using gears,axles, distance between them, andScherer, I admit that that con- ger, but rather a faster micro- and pulleys,could be pro-cannot in any way be influ- tainedsomeerrorswhich processor. Look at it this way. A grammed (by punched cards)enced by the addition of thisshould not have been pub- 32 -bit chip can address roughly to perform computations many phase -linear circuit! Don't trylished. Our difficulty at the time 4.3 x109 bytes, and at present times faster than human and mislead your readers into the errors were discovered was computing speeds (0.1 us),it operators.Itisnot known believing that electronics can that Mr. Scherer (a contributortakes 430 seconds to access whether it had some sort ofdefy the laws of physics! The to our German sister magazine) each of these. A 64 -bit micro- memory and, if so, what form published circuit will give nohad moved and could not be processor would be able to ad- that took. improvement whatsoever in the traced for comment. Inre- dress 18.5 x 10'a bytes. Even if Since Babbage did not succeed verticalpolardiagrampro- sponse to your criticisms of the the computing speed would be (as far as is known) in construc- duced by conventional Link-recentarticle, theauthor increased to 1 ns, it would take ting a practical form of his witz-Riley type filters,as de-replies:"Your correspondent 596 years to access each of design, the Science Museum is scribed in your April 1987 issue,is, of course, absolutely right these addresses. That is why attempting to do this on the for example. when he says that the radiation the big three, Intel, Motorola, basis of the many drawings Bab- There is also a fleeting refer-pattern is determined by the andNationalSemiconductor bage left behind. The Science ence in the article to an evendistance between theloud- have, at present, no intention of Museum isundertakingthe bigger blunder perpetrated byspeaker units.It is, however, developing a 64 -bit device, but project as a tribute to Babbage a certain T. Scherer and pub-also a function of frequency. rather look at more and better on the two -hundredth anniver- lished in the December 1985 When a cross -over network is ways of exploiting the existing sary of his death. issueof Elektor Electronics,added to a system, it may ad- 32 -bit designs. which almost prompted me to versely affect the radiation pat- Roger Harrison write to you at that time; I ex- tern, and it is this that the phase - Martin Callagher London University pected, however, that the suc-linear filter does NOT do. In Boston, Mass. ceedingissuewouldcarryother words, this type of filter some sortof apology, soI does NOT affect in any way the waited to see what would ap- natural radiation behaviour of a pear. I waited in vain, however, loudspeaker system. It is this Sir-It would have been in-as no such apology or ad-latter aspect that was meant in formative to your readers if The mission of error ever appeared. the article; unfortunately, I did INMOS tran.sputer and OCCAMThat article detailed the design not specifically mention that, (EE, November, 1987) had inof a phase -corrected cross -overand I fear that this has given rise cluded a note indicating the in- filter; it turned out to be a lot of to the misunderstanding':Ed. genuity of choosing the name useless drivel! What was de- OCCAM for the language inscribed in the article just will question.The name comesnot work; the principle is fine from William of Occam (c. 1285- for two -polefilters,but be- c. 1349), an English philosopher comes uselessif applied to Sir-I am writing to ask for an best known for his doctrine non four -pole filters as used in that (admittedly subjective) assess- sunt multiplicanda entia praeter cross -over circuit. Isn't it about ment as to which of the two pre- necessitatem (things should not time you were honest and ad- amplifiers, Top -of -the -range be multiplied unnecessarily). mittedthatyou(probably (EE, Nov. 1986) or Valve (EE, uniwittingly; certainly er- March/April, 1987) sounds bet- Dr. S. Whitehorn roneously) published a load of ter. Gloucester rubbish? I look forward to reading in the Cameron Brook near future some small com- Swanbourne, Australia ment published in your maga- Sir-It was the last straw-thezine which will set the record In our opinion, the Top -of -the - camel's back has been broken straightwith regardtothe range unit is the better and also EE December 1987 LOGARITHMIC LCD VU METER

A compact, versatile AF signal level indicationunit with a dynamic range of 60 dB, a dotor bar graph read-out, and a peak hold function.

Not so long ago, coloured LED building a compact indicationThe linear LC display which are readily connected to bars were welcomed as the unit using a sandwich The circuit diagram of this part the respective points on the more robust and faster replace- construction-see the introduc-of the VU meter is given in Fig, amplifier board-Fig. 3 shows ment for moving coil meters in tory photograph and Fig. I. The 2. It would have been possible the completed sandwich con- VU (volumeunit)indication amplifier board holds 2 to use a single display driverstruction. The linear scale of units. An additional, important, logarithmic amplifiers forchip with a suitable multiplex- the LCD gives a read-out which advantage of the LED VU meter stereo applications. Both the ing circuit for the LCD, but this is directly proportional to the was that it enabled realizing the amplifier and the display boardwould have been at the ex- input voltages applied to points peak hold function. which iscan, of course, also work as apense of the peak hold func- L and R, varying between the useful, if not indispensable, for separatemoduleinappli- tion. The inputs of the relatively voltage on the respective REF determining the recordingcationsotherthanthatde-expensive driver ICs are pro- LO and REF HI input (0.5 and levelontapes.Themajor scribed here: the amplifier, fortected against overvoltages by 4.5 V). The level of the supply drawback of the LED based VU instance,isalso suitable for networks D1 -D2 -R5 and D3 -D4 - voltage applied tothe LCD meter is its relatively high cur- driving a moving coil VU meter, R6. Selectionbetweenthe board is governed by the maxi- rent consumption, which poses which is arranged to display avarious available display modes mum permissible supply for the considerable problems in port- linear dB scale. Similarly, the LC is accomplished with the aid of LC display(6V),and the able equipment. The VU meter display board may be used aswire links, jumpers or a switch minimum supply level for cor- described here is based on a an indication unit in,say, anas summarized in Table 1. The rect operation of the driver liquid crystal display (LCD) with electronic thermometer. LCD board has only 4 inputs, chips (5 V). modest power requirements. The read-out is logarithmic with a scale of 60 dB, which is ad- equate for the dynamic range Table 1 of, for instance, a CD player. The logarithmic The built-in peak hold function amplifier It 12 13 DISPLAY MODE has an option for automatic Figure 4shows thecircuit resetafterapproximately2 diagram of I of 2identical seconds. Wire links or jumpers L L X dot mode; 18 steps logarithmic amplifiers, and the make it possible to select dot or power supply for the VU meter. L H X dot mode; 9 steps bar indication, but it should be Opamp Atraisestheinput noted that the peak hold func- H L X bar mode; no peak value signal and feeds this to a peak tion operates in the bar mode H H L bar mode; peak value, automatic reset rectifier circuit. The logarith- only. mic amplifier, composed ofA.2, H H H bar mode; peak value, reset: 12= low The proposed LCD VU meter is A3 and matched transistors T2 H = no wire link composed of 2 units, namely a andT2,is driven with if(c2), logarithmic amplifier and a lin- L = wire link fitted which is directly related to the

X = immaterial ear LC displaydriver.The amplitude of the input signal. printed circuit boards for these The matched transistorsare have the same size to enable housed in an IC Type CA3046, EE December 1987 3

Fig. 1 The completed display driver board (I) and the logarithmic Fig. 3 The 2 boards can be fitted in a sandwich construction to amplifier board (r) have the same size. make the VU meter as compact as possible. the 4 opamps in an IC Type 2 LIv1324. The linear variation of the rectified input voltage is converted to logarithmic by means of an

5 -.4 opamp with a feedback circuit BV O that comprises a conventional bipolar transistor. Under cer- C31 R3 R1 0 01623 tain conditions, the collector t0On 22 21 current of a bipolar transistor tt 20 IC rises 19 exponentially with the 1m1m 15 3903 4754 base -emitter voltage. Figure 5 27 17 16 shows how this phenomenon is 15 exploited: the transistor forms 14 23 Oa. .r. 13 the resistance in the negative 12 11 feedback circuit of an opamp, 26 I.0 10 which thusfunctionsas an 9 amplifier that translates its lin- 7 ear input signal into a logarith- 01 24 II 12 130R mic output. 41 3 21 The voltage transfer of this cir- 6 57 cuit is written as a b °' 11111111101.,)d. R7 MI I U0= -k-i-Tloge [1] 131-54 = 1N4148 q ctkoR LCD, 2 x 18 -BARS LTD 321 -001 0 5V mimmumin in which a is the current ampli- 11 41556. fication of transistor T, and kr/ q 2171- at room temperature works out off24 t ; - 6 at about 26 x10-3. The weak 9' 7 point of this circuit is that the term ieo is strongly tempera- 13 4754 11 ture dependent. Figure 6 shows

13 a slightly more complex circuit y R6 14 whose voltage transfer is less MEI 15 affected by temperature vari- 17 04 26 t8 ations. The voltage transfer of 19 this circuit is 20 21 22 23 _(R6+ Rio)/c11,. UiR 11 12 133'8 Uo_ 7=7r" R q Molts The factor kT/q is the same as

67505 .2 in equation [1], while aleo has been eliminated, ensuring reasonable temperature stab- ility. Compensation of lerl q was foundunnecessaryforthe givenapplication,since it Fig. 2 Circuit diagram of the linear LCD driver. proved to have little effect on EE 24 December 1987 the relatively low resolution of the LCD. Returning to the circuit 4 diagram of Fig. 4, operational 78L05 amplifier At inverts the 5V logarithmic voltage, so that the

LC drivers receive a signal with 2V5 the correct polarity. The resolution of the display is 0!110 fairlylowat 18 bars.The logarithmic amplifier is dimensioned such that a variation of A1-84 = IC 1 OC1= L14324 the input voltage of 3 decades T2, T3 (72; Ti) =t1C 2k CA3046 results in an output voltage variation of 0.5 to 4.5 V. This corresponds to 1.33 V per decade. The full rangethencor- responds to a scale of 60 dB (-50... +10 dB) as shown in Table 2 and Fig. 7. Considering that 0 dB 775 mV on C2, a dynamic range of 60 dB means that the minimum voltage for illumination of the lowest bar is 2.45 mV, which is about equal to the offset of the input voltage. It should be noted that the value of 775 mV on C2 is not related to the definition of 0 dB as 1 mW (775 mVnr) in a load of 600 Q.

The drive margin of the logar- 5)57.5-4 ithmic amplifier is ensured by feeding itfromtheinput voltage for the 5 V regulator, Fig. 4 Circuit diagram of the power supply and 1 of 2 identical logarithmic amplifier channels. ICs. Resistors R7 and Rs are dimensioned such that the output Table 2 voltageof At can notrise above the supply level of the LCD board. Indication Utc21Uo (A4) IdB1 IrriV1 [VI Construction and +10 2450 4.5 setting up 0 775 3.83 The components are fitted as -10 245 3.17 per the directions in the parts -20 77.5 2.5 list and Figs. 8 & 9. The LCD -30 24.5 1.83 used is the type LTD -321-001 from Mullard/Videlec.The -40 7.75 1.17 outer 2 bars of each row of 20 , -50 2.45_ 0.5 on this LCD are not used in the present application. The virtu- Fig. 5 The most rudimentary form of the logarithmic amplifier. ally symmetrical pinning of the mal position, the display (2 x 26 display, in combination with the pins) is fitted as far as possible layout of the printed circuit to the right-hand end of the ter- board, make it possible to fit the minal strips (2 x 28 pins). In the display upside down also. The reversed position, the PCB is contrast of the LCD is maximum still held as stated before. How- when this is viewed straight, or ever, the position indicator on from one side. The display is fit- the LCD is then at the right, and ted either normally or reversed the LCD itself is fitted as far as -but alwaysatthe copper possible to the left-hand end of side-depending on whether it the terminal strips. is to be viewed from above or Preset Pi is adjusted such that below. Itis recommended to 0 dB corresponds to a direct use terminal strips for mounting voltage of 775 mV on junction the LCD Take note of the pos- R4 -Rs. This results in 3.83 V at ition indicator, which is at the the output of the logarithmic left side of the LCD when this is amplifier, and illumination of 15 viewed in the normal position, bars on the LCD. A different dB i.e.,facingstraightorfrom scale can be set up by redimen- below. The PCB should be held sioning of Rs...Rio inclusive. If such that the EPS number is the input signal has a DC com- Fig. 6 This circuit is derived from that in Fig. 5, but is less affected always upside down. In the nor - ponent, blocking capacitor Ci by temperature variations. EE December 1987 is fitted with the corresponding polarity. The reset period of the peak detector is the product of R11 and Ca. This period can be Parts list kept relatively short thanks to the fact that peaks in the input DISPLAY BOARD (FIG. 81: signal are already retained and displayed with the aid of the Resistors (±5%): 5.2m peak hold function. The input 131;132= IMO 'signal level can be adjusted R3;R4= 1K5 meta, -rx:c-ilt, >5-7 with PL If necessary, Ai can be Re:R6=10K dimensioned for a higher am- R7= 12K Fig. 7 Showing the position of the dB values on the face of the LC plification by increasing the Capacitors: display. value ofR3. TN' CI;C2= 390p C3=100n

Semiconductors: Di. .. D4 incl. = 1N4148 ICI;IC2=HEF4754.

Miscellaneous: LCD= LTD - 321 -001 (MullardiVidelec; far distributors see Infocard 507 in the April 1987 issue). K1;K2= jumpers or terminal strips; 2 x3 contacts. PCB Type 87505 (available through the Readers Services).

Available from Universal Semiconductor Devices Limited 17 Granville Court Granville Road Hornsey London N4 4EP. Telephone: (01 384) 9420. Telex: 25157 usdco g. Fax: 01 348 9425.

STEREO LOGARITHMIC PREAMPLIFIER (FIG. 9):

Resistors (±5%): 111;Rt'=390K Fig. 8 Track layout and component overlay of the LCD board (circuit diagram: Fig. 2). The LCD is fitted R2;R2';R7;R7';111o;R1o'; AT THE TRACK SIDE. Mt:RW=100K 1:13.:R3' = 220K R4;R4' = 39OR Fle;Re'=1K0 116;Re'=3K3 Re:Re'= 120K Rs;Fis'= 15K 1'112:R13=560R PI;Pi' =100K preset

Capacitors: C1;C1'=4p7; 16 V C2;C2' =22 p; 16 V Ca;Ca' = In0 C4:C4' =680p C5:Cs' =100p C6;C6.;C7 = 100n Ca=330n Cs= 100p; 3 V; tantalum bead

Semiconductors: D ';D2:D2' = 1N4148 TI;Ti'=BC5578 ICI;IC1' = LM324 IC2=CA3046 IC3=78L05

Miscellaneous: PCB Type 87520 (available through the Readers Services). Fig. 9 Track layout and component overlay of the stereo logarithmic amplifier board (circuit diagram: Fig. 4). EE 26 December 1987 BRITISH AEROSPACE: 10 YEARS IN SPACE

When we speak of British Aerospace, we normally think of Concorde and the company's other work in aircraft production and engineering. But, in the first 10 years of its existence, this industrial giant has also become world renowned for its work in space engineering and electronics.

British Aerospace was born on six new civil aircraft program-datarecordersandengine simulation, electronic support 29 April, 1977, by the amalgama- mes. health monitors. measures,allied with ex- tion of British Aircraft Corpor- AlthoughBritishAerospace Missile aerodynamic and perienceincommunications ation, Hawker Siddeley consistsofsevendivisions, rocket -thrust vectorcontrol and message handling,pro- Dynamics, and Scottish Avia- employing a stable workforcesystems are supplied as well as vides the Division with a C31 tion, companies whose averaging 75,000 people. thiselectro-hydraulic power units. capability. antecedentscan betraced article deals primarily with theMissile gyroscopes produced Antennas and antenna systems back to the dawn of powered SpaceandCommunicationsinclude the Microflex gyro. are produced for aircraft, land aviation in the first decade ofDivision at Stevenage, employ-Sea Archergunfirecontrol vehicles and ground based use. this century. ing around 1,600 people, but asystems are supplied for naval Lord Beswick was its first Chair- brief summary of the activitiesships. The Interceptor surveil- man. He was succeeded inof the Electronics and Equip- lanceandgunfirecontrol Space and March 1980bySirAustin ment Division (3,200 personnel) system for offshore patrol craft Pearce. This was the final year is also given. is offered. Compass equipmentCommunications in which BAe operated as a na- and vertical reference units forDivision tionalized corporation. On 1 ships are also available. British Aerospace isBritain's January, 1981, the business was Electronic Systems A field artillery battery com- leadingspaceengineering vestedinBritish Aerospace puter is manufactured for thecontractor, and the Division is PLC. and Equipment Swiss Army. Tilt sensors arethe largest organisation of its In 1983, Sir Raymond Lygo was Division supplied for tanks. Ajax is atype in Europe. It has its head- appointed Managing DirectorThe Division produces a wide sensor and fire control systemquarters at Stevenage where of Bike, and in 1985, the year that range of navigation and for anti -armour off -route mines work on the design and con- BAe was fully privatized, he wasguidance systems for land, sea using LAW -type projectiles. structionofcommunications appointed its Chief Executive. and aerospace use, plus data Data handling, message satellites is concentrated. Today, BAe is the UK's largest handling, message switching switching and disc memory Communicationssatellitesin exporter of manufactured and electronic warfare systems. systems are built. A Royal Navy service for which the Division goods, with an order book ap-A new activity is the develop- main communication centre has was prime contractor include proaching £10 billion. By com-ment of antismuggling cargo been equipped with an advanc- OTS (now retired), Marecs-A parison, the order book in 1977 examination systems. ed message switching system, and B2, and ECS-1 and 2. The stood at £2 billion. Then, salesAvionic products include laser and smaller message switching Division is responsible for a were £800 million,of which gyro inertial navigation andformattingsystemsare further nine communications £530millionwereexports. systems.strapdownattitude made for naval vessels. satellites now under construc- Today, the respective figuresand heading referencesys- An infra -red jammer for tion.Theseare ECS (2 -off) are £3.1billion and over £2tems,gyrocompasses, twin - helicopters to counter infra -red Skynet 4 (3 -off), Olympus and billion. gyro platforms,flightinstru- missiles is available. Electronic Inmarsat 2 (3 -off). As principal BAe has established itself as ments,crash -protectedflight warfare, electronicwarfare subcontractor, the Division is Europe'slargestaerospace also participating in the largest company with the widest range contractforcommunications ofproductsofanysuch satellites yet placed.Itisto companyanywhereinthe build Intelsat VI satellites. The world. Its portfolio of products Eurostar communications satel- stretches from underwater lite is also marketed in associ- systems, through ship -launched ation with Matra. missiles, ground -launched Other projects of the Division missiles,military aircraft and are Hotol (horizontal take -off air -launched missiles, civil andlandinglauncher),and airliners and business aircraft, Space Platform, a free -flying ve- to satellites for communications hicle to operate in conjunction and scientific research. with manned space stations. This position owes much to the The Division also includes a substantialinvestmentBritish major space engineeringfa- Aerospace has made in cility at Bristol concerned with developingatotalproduct scientific satellites and equip- strategy, which is most evident Fig. 1. Flexible manufacturing system for the automated production ment, the development of solar in the launch of no fewer than of electronic units. arrays, and the Skylark soun- EE December 1987 ding rocket. Giotto, the Halley's transmissions in the 4 GHz and multi -purpose, high-power transponders capable of hand- Comet spacecraft, was built 6 GHz bands. Power (750 W) is communications satellites with ling 200,000 half -telephone cir- there along with units for the derived from 13.8 m -span solar direct broadcast capabilities. cuitsortheequivalentfac- NASA/ESA Hubble Space Tele- arrays. Members of the Olympus fam- simile,telex,data,and TV scope. The Division is involved MARECs are operated by the ily will vary in size and weight, transmissions,orupto 12 in numerous other space engin- European Space Agency and andpower -generation and fullpower direct broadcast TV eering projects as a major sup- used by INMARSAT-the multi- communications facilities,ac- services.Typicalcommuni- plier of systems and equip-national International Maritime cording to the particular oper- cations frequencies are direct - ment. Satellite Organization. ational role for which it is re- broadcast TV 11.7-12.5 GHz; quired. The largest versions specialized business services: could generate7.7 kW from uplink 14-14.25 GHz, downlink solar arrays of 60 m span. 12.5-12.75 GHz; high -power European Communi- Olympus Olympussatellitescanbe communications 20 to 30 GHz. cations Satellites Olympus satellitesarelarge equipped with up to fifty 50 W Olympus -1hasapre -oper- The European Communications ationaldirect -broadcast TV Satellites (ECS) providea channel for Italy and a second European communications net- steerablechannelforex- workfortelephone,telex, perimental use by members of business data, facsimile, and TV the EBU. Itwill be launched traffic. The programme calls for from Kourou, French Guyana, in five satellites in all, of which the near future and be pos- ECS-1 and ECS-2 are in service. itioned in geosynchronous or- ECS-3 was lost because of an bit at 19° W. Arianelauncherfailurein Under the leadership of the September1985.ECS-4 was SpaceandCommunications launched, together with Division, an international con- AUSSAT (anAustralian com- sortium comprising Aeritalia, municationssatellite)inthe Selenia-Spazio,Fokker,and earlyhours (BST) of 16 SparAerospacewillbuild September last by Ariane 3. It is Olympus communications at present being tested before it satellitesandmarketthem is taken into service and will worldwide. then be designated Eutelsat 1- F4. Its geosynchronous position Fig. 2. European Communications Satellite. will be 10° E. Eurostar These satellites are operated by the European Space Agency for Eurostarisamedium -size Eutelsat-the 20 -nation as- satelite, larger than ECS-class sembly of European PTTs-and satellites, but smaller than the for the Europeam Braodcasting Olympus series. It can be car- Union (pan -Europe TV). They ried by, and launched from, Space Shuttle Orbiters, or it can contain 12-14 transponders capableofhandling upto beoneoftwosatellites 12,600 telephone circuits and launched by Arlene. being car- two TV transmissions.Their ried aloft on the Ariane's Spelda power (1,200 W) is derived from structure specially developed 13.8 m -span solar arrays. by BAe for dual -launch missions. Eurostar is the first product of Maritime Communi- SatcomInternational,ajoint cations Satellites venture of BAe and Matra of (MARECs) France to design, build, and The role of MARECs is to pro- Fig. 3. Marec maritime communications satellite. supply communications satellites on the international videglobalcommunications between ships and shore sta- market. canaccommodate tions. MAREC-A was launched Eurostar communications payloads up to inDecember 1981 andis operating in geosynchronous 250 kg mass and supply them orbitpositioned overthe with 700 W RF power. Maxi- mum power generated by its Atalanticat26° W. Thefirst solar arrays is 3.2 kW. MAREC-B was lost in September 1982 due to a failure of the Ariane launcher. Its replacement was launched on 10 Skynet 4 November, 1984. It is positioned Skynet 4 is a series of military in geosynchronous orbit over communications satellitesfor the Pacific at 117.5° E. the UK armed forces. Its design The satellites have one 2 m is based on that of ECS with diameterdishfor ship -to - communications equipment satellite communications in the operating in the X -band sup- 1.5 GHz and 1.6 GHz bands, and plied by Marconi. Each satel- two horns for satellite -to -shore Fig. 4. Satellite transfer vehicle (single launch). lite's 16 m ofsolararrays EE 28 December 1987 generates 1,200 W of electrical 100nations,providesinter- power. The first two satellites in national communications ser- theseries are launched by vices by satellite. Structures for Space Shuttle. the Intelsat III series were supplied in an association with this INMARSAT-2 series of communications satellites dating back to 1966. Sub- Inmarsat-2 is a family of second - sequently, BAe's involvement in- generation maritime communi- creased and it became the prin- cations satellites being built for cipal overseas contractor in the the International Maritime Satel- Intelsat N and IVA program- lite Organization. Although the mes. BAe was also the only non- initial contract calls for three Amercian contractor to supply satellites,options exist to equipment for the US domestic supply a further six. Comstar satellitesdeveloped The satellites provide 250 voice from the Intelsat N design. Fig. 5. Big Communicator satellite clusters. channel for ship -to -shore com- BAe is the principal offshore munications,and 125 voice contractor to Hughes for the In- second communications with present-daysatellitedesigns. channels for shore -to -ship links. telsat VI programme. Space-mobile vehicles, and a third With the latter, if it is a three - Ships' terminals operate in the L craftstructures, power elec- communications withfixed axis stabilised spacecraft, the band (1.5to1.6 GHz),while ground stations. As the traffic solar arrays are aligned North to shore stations use the C band tronics, cable harnesses, C and B band antenna reflectors, and associatedwithaparticular South. In contrast, the solar ar- (3.6 to 6.4 GHz). Hughes Aircraft the complete cradle for sup- region increased, extra rays of the equivalent Big Com- is supplying the satellite com-porting and launching space- satellites of the required type municator satellite are aligned munications payload. craft from Space Shuttles will be could be added to a cluster to East to West and remain fixed The Inmarsat-2 design is based supplied for this programme. providetheextrafacilities pointing at the Sun. They are at- onthatofEurostar. These The C -band dish, three metres needed. tached to an open framework satellites have a design life of 10 in diameter, is one of the largest All the satellites of a clusterwhich comprisestheouter years and can be launched byantennas made from carbon would be able to intercom- body of the satellite. Ariane or Space Shuttle. fibre to be constructed for use municate,informationbeing Mounted on bearings inside in space. The antenna must relayed between them via laser this framework is a drum that withstand the harsh conditions links to avoid interfering with containsthesatellite'scom- of satellite launch and remain the communications traffic be- municationsequipmentand dimensionally stable in space, tween the satellites and Earth. other systems. The communi- retainingitsaccurate profile, Laserlinkswouldalsobe cations antennas are deployed despite daily temperature employed to relay communi- from one end face of the drum, changesfrom -150'C to the rotation of which is con- 4-140'C. lite clusters This would enable trolled sothatthe antennas a connection to be established always point towards Earth. One directly between two users on advantage of this layout is that differentcontinents,situated the drum is shielded by the The Big remotely from each other, with- solar arrays from the direct rays Communicator out the need for multiple Earth - of the Sun. Better heat dissi- satellite -Earth hops to be set up, pation from the interior of the The geosynchronous orbit in as is now the case. satellite is also obtained which communicationssatel- Thisconcept of satellites through the drum's ends which lites are positioned is already operating in clusters has been permanently face outer space. becoming crowded. This is es- named the Big Communicator pecially true of sectors in which by British Aerospace. satellites are placed to coverThe geometry of Big Com-Giotto Fig. 6. Giotto - the Halley's specificgeographicalareas Comet spacecraft. municator satellites differs from Launched on 2 July 1985 from generating high volumesof communications traffic, such as NATO IV Europe and North America. BAe is designing two militaryThe demandforcommuni- communications satellitesfor cations services provided by NATO. Given the designationsatellitesisincreasingand NATO N, these satellites will within the next 15 to 20 years the provide members of the network could be saturated alliance with secure militaryunlesssome technological and diplomatic communi- solutions are found to expand cations facilities. The first NATO the available capacity. IV is scheduled to be launchedFollowing studies of the prob- in the early 1990s. Both will re- lem one answer proposed by main in service beyond the yearBritish Aerospace is to establish 2000. clustersofsatellitesatpar- In design, the NATO IV satel- ticularorbitalstations.The lites are virtually identical toseparatesatellites forming a Skynet 4. cluster would be dedicated to fulfilling different roles. An in- itialclustercould comprise Intelsat Series three satellites. One to provide Intelsat, a consortium of overdirect broadcasting services, a Fig. 7. Columbus space platform. EE December 1987 Kourou by Ariane 1, Giotto was Aerospace concept that was initially placed in a geosyn- proposedby Britain and chronous transfer orbit, follow- adoptedbytheEuropean ing which it was boosted into a Space Agency as one of the heliocentrictrajectorytoin- fourmajorprojectsinthe tercept Halley's Comet. European Columbus pro- Giotto intercepted Halley's gramme which could be part of Comet during the night of 13 Europe's contribution tothe March1986.Conditions be- manned space station being came increasingly hostile dur- developed by NASA. The Plat- ing theencounter.Giotto form would provide the station penetrated the dust cloud sur- with an equipment carrier, con- roundingthenucleusand trolled to operate with it, but at because Giotto and Halley's a sufficient distance for the Plat- Comet orbit the sun in different form not to be affected by the directions, this occurred at the contamination and clutter sur- very high relative velocity of rounding the station, or to im- 68 km/sec (about 150.000 mile/ pede visiting traffic. Whenever hour). required, Space Platform could Giotto's mission was the most be manouevred to dock with successful space science event Fig. 8. Space telescope solar arrays being tested. the station. As a free flyer, the Platform could be placed in a of 1986. Of the five satellites sent solar magnetosphere, the struc- to observe the comet, Giotto scopic observation will be in-polar orbitforEarth obser- made theclosest approach, ture of the sun/wind interface, creased by the huge factor ofvation applications or be con- theinterplanetarymagnetic 350, and objects 14 billion light passingwithin608 km (378 trolledtoco -orbitwiththe miles). Close-up photographsfield, solar and galactic cosmic years distant will be seen. space station. It could also fly at rays, and dust. The magneto- Under contract to the European relayed back to Earth by Giotto higher or lower altitudes than sphere of Jupiter will be exam- show a potato -shaped object Space Agency (ESA), (BAe) de- the station, depending upon the ined on the way. signed and built the solar arrays measuring 16 km by 8 km by requirements of the equipment 7.2 km. The nucleus is very fortheNASA/ESA Hubble being carried. Space Telescope to be porous with a densitity less than Space Platform is a vehicle that launched into orbit by a Space Hipparcos can be replenished and,if that of water. The comet rotates Shuttle. These are the largest once every 53.5 hours and has a Hipparcos is being built for necessary, refurnished in orbit very dark surface that reflects solar arrays to be constructed in to act as a permanent satellite ESAandisEurope'sfirst Europe. The total area of the only 3% of the incident sunlight. astronomic satellite. It will ac- bus inspace. The Platform two arrays is 60sq metres. (Forwould provide all the services The pictures taken by Giottocurately measure the positions further details see entry on show clearly a number of active and proper motions of more requiredforavarietyof Solar Arrays). payload modules. These would areas from which masses of gas than 100,000 stars. BAe has also developed and anddustarecontinuously be carried up from Earth by BAe is supplying the power made the ultra senstive Photon ejected.Evidenceindicates distri- SpaceShuttle,orasimilar system and electrical De ctectorAssembly (PDA) thatHalley's Comet consists reusable launch system, and at- bution network and, with Matra, which is the sensor of the faint mainly of water (80%), with car- the attitude and orbit control tached to the Platform. At the bon dioxide as the next most object camera, one of the fiveconclusion of their missions, units for the satellite. focal plane experiments associ- abundant compound. Hipparcos has a design life of themodules would bere- Other experiments carried out ated with the Hubble Spacetrieved and returned to Earth. 2.5 years and is scheduled to be Telescope. The PDA detects in- by Giotto measured the Typicalpayloads would be launched by Arianeinthe dividualphotonsemanating chemical composition, size and course of next year. communications equipment, abundance of dust grains, and from the object under obser-astronomical instruments, Earth the surrounding atmosphere of vation so that a visual image ofobservation sensors,material electrically charged particles. Hubble Space the source can be built upmanufacturing systems, 50times Giotto continues in orbit and revealingobjects biologicalexperimentsand Telescope fainter than those now visible will arrive back in the vicinity of other scientific equipment. The Hubble Space Telescope from the Earth. Earth in 1990, when it may bewill enable objects to be ob- The main structure of the Plat- given another scientific task toserved that are over seven times form and all the systems could perform, such as interceptingfurther away than can be seen be carried up to low -Earth orbit Comet Grigg-Sjellerup in 1992. with terrestrial telescopes. The Space platform and assembled there during one Space Shuttle mission. Dur- universeaccessibletotele- SpacePlatformisaBritish ingasecondmissionthe Ulysses payload modules would be BAe has developed attitude and added. The Platform has its own orbit control equipment and the propulsion system which would 1.6 metre high -gain antenna for be used to move itinto the Ulysses. the European satellite desired orbit. to be used for the deep -space Space Platform is designed to International Solar Polar Mis- be extendable. Initially the Plat- sion. During the 4.5 years of this form could, typically, have four mission, the satellite will use payload module berthing the gravitational pull of Jupiter points,generate up to 5kW to swing it out of the ecliptic electrical power, have a fully place over the poles of the Sun. active cooling system and a The satellite's mission is to in- data communications link, via a vestigate the solar wind and Fig. 9. Hotol. data relay satellite, operating at EE 30 December 1987 up to 300 MBPs. It would orbit at Spacelab shuttle altitudesbetween600and pallets 800km. As a member of the nine -nation Spacelab consortium BAe was Hotol responsible for the design and manufacture of Spacelab Shut- Hotol (horizontal take -off and tle pallets - large structures landing launcher)isan un- (height 2.24m,width,4.35m, manned reusable single -stage length 2.93m) that act as plat- vehicle for placing spacecraft forms on which unmanned ex- in low -Earth orbits.It will be periments are mounted for car- capable of lifting payloads up to riage in the cargo bays of NSA 7000kg mass transported in a Space Shuttle Orbiters. Up to cargo bay 4.5m in diameter by 4130kg weight of experimental 9m long. In effect, Hotol is an Fig. 10. Spacecraft assembly hall. equipment can be carried on a unmanned aircraft powered by pallet. Eighteen Spacelab an air -breathing and rocket pro-ment and industry, has beena third system has been built palletshave been manufac- pulsion system. It can take -offallocated fo fund a proof -of - ready for the first Ariane 4 mis- tured and delivered. andland -onrunwaysfrom concept study of Hotol. The sionin 1986. BAeisalso A pallet equipped with five which theConcorde couldstudy will last up to two years building the Spelda structure OSTA-1 experiments was car- operate. which will enable Ariane 4 to ried in the cargo bay of NASA's It is proposed as a more econ- carry and launch two satellites Orbiter Columbia in November omical vehicle than the Space during the same mission. 1981 during the second Space Shuttle for the task of launching Skylark Shuttlemission and another spacecraft. Hotol can lift loadsSkylark is a sounding rocket for with OSS experiments was car- similar to those carried cur-space research supplied by Spelda ried on the third mission in rently by Ariane, and would BAe.It can carry experiment March 1982. A pallet formed provide Europe with the facilitypayloads to alitudes of 1000km Spelda (structure porteuse ex- part of the manned Spacelab as- it needs both to remain com-and is being used by the West terne pour lancement double sembly which was carried into petitive with the US Space Shut- German Space Agency, DFVLR. Ariane) is part of Ariane 4's spaceforthefirsttimein tle in the future, and to retain itsThe first Skylark rocket was payload -bay primary structure. November 1983 abord NASA's general capability in space. launched in 1957. To date 400 Availablein two versions - Orbiter Columbia. Two pallets The reasons Hotol will be able havebeenlaunchedfrom short (3.78m, 348kg) and long were used in the recovery from to operate at a lower cost thanranges around the world in(4.78m, 393kg) - Spelda is a space of the Palapa and Wester Space Shuttle or other conven-various research programmes. cylindrical structure 3.97m in satellitesbySpaceShuttle tional launchers, are: One oftheseistheWest diameter with a truncated con- Discovery in November 1984, it uses atmospheric oxygen German Texus project in whichical upper section. One satellite and a three pallet 'train' formed as fuel during the initial flight the nature of materials under is carried on a mounting ring fit- partoftheSpaceShuttle phase resulting in a great sav-microgravity conditions is be- ted to the top of the conical sec- Challenger Spacelab 2 mission ing in the all -up weight of the ing investigated. tion, and the second satellite is in July 1985. vehicle at take -off. Currently all Depending upon the payloadenclosed within the cylindrical Half and quarter -length pallets spacecraftarelaunched bycarried and theversionof portion. After the Ariane 4'shave been designed, and a rocket -powered vehicles using Skylark used different spacenose cone is jettisoned, the top study has been completed for a fuels in which the oxygen con- missions can be performed. satelliteisreleasedthena proposal to useSpacelab tent can account for as much as Payloads from 100kg to 400kg in pyrotechnic line charge splits pallets as autonomous general- 85% of the total fuel weight at weightcanbecarriedto Spelda in two around its cir- purpose free -flying spacecraft. take -off. Fuel weight at take -offaltitudes ranging from 150km to cumference and the upper sec- can be greatly reduced by 1000km. The usefultime tion is propelled away by a pre - using a combination ofair - available for microgravity ex- compressedspring system breathing and rocket propul- periments can be eightleaving the second satellite free Satellite launch sion to provide power. Hotel's minutes, with significantly to be released into orbit. cradles air breathing engines drive it to longer periods available for ex- Spelda can accomodate two BAe has built and delivered a Mach5 at26km(85,000ft) traterrestrial research projects. Class 1 or Class 2 satellites ofreusable cradlefor carrying altitude before rocket power is between 800 and 1400kg mass and launching Hughes Leasat required. each. military communications itis unmanned and, there- Spelda is of monocoque sand- satellitesdirectlyinto space fore, from the engineeringAriane wich construction comprising from the cargo bay of a Space point -of -view is a much simpler BAe designed and installed thean aluminium honeycomb core Shuttle Orbiter. A Leasat satel- andlesscostlyvehicleto Ariane hold-down releasebonded to multi -layer carbon - lite weighs 6000kg at launch. design and build. systems used on the launchfibre skins, with outer The cradle is a primarily alu- Hotol is completely reusable platformatKourou,Frenchglassfibre layers covered with miniumstructureweighing having no costly expendable Guiana. BAe also supplies a var-aluminium foil. 750kg.Itis2m wide and parts such as boosters, or exter- iety of high technology prod-BAe designed Spelda and has measures 5m across its open nal fuel tanks. ucts for Ariane including thecompleted two engineering de- face. Hotol could be built and oper- auto -pilot electronics unit, velopment models and the first BAe also has the task of design- ational by the early years of the solenoid valves,gaiters andprotoflight unit which is to be ing and supplying reusable 21stcentury.Laterversions carbon -fibre struts for gimball-used on the first Ariane 4 mis- support cradlesfor carrying could carry men into orbit toing the engines of the secondsion scheduled for July 1986. and launching Intelsat VI series servicespaceplatformsor stage. Work has begun on a further communications satellites from other equipment in low -Earth A second launch -padhold- fiveproduction Speldasre- Space Shuttle Orbiters. Intelsat orbits. £3 million, contributed down release system was in-quired for the initial series of VI satellites weigh 3500kg at equally by the British Govern - stalled in 1984 for Ariane 3, andAriane launchers. launch. EE December 1987 Solar arrays using special tools. The arrays which can be lowered 4.5m solar array drive units capable For the past 20 years, BAe hascan be deployed and retracted (14ft) below floor level permit- of supporting producing up to built solar arrays and deploy-independently andalsore- ting satellites over 12m (40ft) tall 6kW per drive unit. ment mechanisms for a number placedinspace,thedis- tobebuilt.Class 100,000 Instrumentationsensorspro- of spacecraft. These have in-mounted arrays being returned cleanliness conditions prevail, duced includesunsensors cluded the Ariel 3, 4 and 6, X-3 to Earth for refurbishment. and the temperature is main- orientatingsolararrays; a (Prospero) and X-4 (Miranda), tained at 20 °C ± 1 °C with rela- sensor for detecting microwave and Cos -B scientific satellites. tive humidity at 45% ± 5%. The emissions from sea surfaces; Twelve solar array sets wereSpacecraft assembly .steelframed building providesand aninfra -redradiometer provided for Intelsat IV and IVA hall limited electromagnetic protec- which was installed aboard the communications satellites, and In 1984 a new spacecraft as- tion and the floor is electrically American Nimbus 7 advanced four sets for the American Corn - sembly hall was completed. conductive to prevent residual atmospheric research satellite star satellites. This new facility was estab-electric charges accumulating. to monitor energy output from More recently, BAe has beenlishedto enable thelarger Electromagnetic compatibility the Earth's upper atmosphere. developing the flexible roll -outsatellites now being developed testscan be conducted on Utilizing the hardened version arrays having a total area of 60sq to be assembled at Stevenage. satellites in the hall. In an adjac- of the Texas Instruments SBP m for the NASA/ESA HubbleAt any one time as many as four ent room are four computer -9989 microprocessor, BAe has Space Telescope. Each wing ofsatellites can be under con- controlledcheckoutstations built a spacecraft microcom- thisarraymeasures 11.82m struction in the hall. Satellites used for testing satellites andputermodule (SMM) for (span) by 2.83m. The complete currentlybeingassembled their equiment at various stagesgeneral use in satellite systems array comprising some 48,760there include the Olympus -1 in their construction. requiring data processing ser- silicon solar cells, weighs 160kglarge multi -role communi- vices. Up to 64 SMMs can be and generates 6kW at the be-cations satellitefor ESA, and linked together,ifrequired. ginning of its life in orbit. Skynet 4military communia- Spacecraft equipment Software needed to control the The arrays are unreeled from tionssatellitesfortheUK BAe has built power -condition- operations of SMMs is available. drums and deployed automati- Ministry of Defence. ing equipment for more than 30 The SBP 9989 was selected as it callyeithersideofSpace The assembly hallis a win- satellites, stabilisation systems is bipolar I2L device resistant to Telescope. A duplicate drivedowless building 27m(88ft) for both spinning and three -axis radiation damage. and duplicate wiring is pro-long, 27m (88ft wide) and llm stabilisedsatellites,and has vided. Provision has also been (36ft) high. It has two developed and tested reaction made for the arrays to be un-hydraulicallypowered plat- and momentum attitude control rolled manually by astronautsforms, each 7.5m (25ft) square, wheels. BAe supplies a range of

THE NEW AT&T

Forced to compete for the long- data, and video information. reality,providing onetrans- the end of 1986, is expected to distancemarket with lower - Moves toachievethisgoalmission path and onetele- grow to 1.4 billion miles by 1990 priced carriers like MCl/SBS range from internal restructur-phone numberforspeech, and to be 50% digital by then. and US Sprint, AT&T has never- ing to joint ventures abroad data, text, and image Inthecomputerbusiness, theless kept more than 70% of with strategic overseas partners worldwide.Itsupports inter- where AT&T has suffered heavy that market. In this and other (e.g., Philips in the Netherlands;national standards (which re- losses,the company is now areas where AT&T has always Korea's Lucky Goldstar group;duce design and manufactur-stressing data networking and been strong, it remains strong. 17companies in Japan;the ing costs) and open architec-positioning itself to compete in But how well can the company National Telephone Company ture for systems (which ensuresthe communications market for use its traditional strengths to of Spain; and a 25% equity stake the logevity and usefulness ofsmall and medium-sized com- offset weaknesses in such areas in Italy's Olivetti). AT&T equipment). AT&T's fibre puters. Computer revenues by as computer products whe,re it AT&T is pushing to make ISDN a optic network, 10,000 miles at 1991 are expected to lead all has less experience? product revenues ($2.8 billion Frost & Sullivan's report AT&T for computers, followed by $2.7 Market Strategy to 1991(#A1823) LONG-DISTANCE COMPANY MARKET SHARE billion for central office says that the company's strategy 1986 switches, and $2 for PBX sales). looks to boost its revenues and modest earnings by cost cutting, by more capital spending AT&T 72.6% to strengthen core businesses, by increasing its efforts in the international markets, and by continued efforts to get federal authorities to remove the cap from what AT&T can earn from longdistanceservice(efforts the report predicts will succeed). AT&T is not modest about its long-term goal. It simply wants MCVS8S 13.7% to be the world leader in the in- MAY: rrst f U1111... rK. ratccet tegrated management of voice, EE 32 December 1937 TEST 8c MEASURING EQUIPMENT

The field of electronic test and measuring equipment is large and still growing. Although not so long ago even an electronics engineer could get by witha multimeter, an oscilloscope, and a signal generator, nowadays even a small laboratory or workshop is equipped with an array of general purpose instruments, suchas multimeters and power meters, various signal generators, a frequency counter, distortion meter,wave or spectrum analyser, and one or two oscilloscopes. Inmany cases, this is complemented by an LCR meter, Q meter, waveform recorder, a storage oscilloscope, and others. To help readers find their way in this sometimes bewildering variety of equipment,we start this month a regular series of reviews of such equipment. Since theoscilloscope, after the multimeter, is probably the most frequently used instrument inan electronics environment, the series is started with a review ofa number of dual -trace oscilloscopes. The author of the series is Julian Nolan. Part 1: dual -trace oscilloscopes (A) Hitachi V-212 £27.50 each (x10/ x 1) it is well worth considering alternatives Hitachi is a Japanese company such as the Coline range of which is perhaps best known modular probes, which start at for its consumer products, es- £13.66 (x1);theswitchable pecially in the video and hi-fi x 1/ x10 version costs £17.84. fields. The V-212 is one of a high voltages, x10 probes have comprehensive range of os- to be used, especially in the cilloscopes manufactured by dual trace mode to prevent the company, covering from the over -scanningofthetrace. V -058G, a dual trace 5 MHz ultra Although not restrictingthe compact scope, to units such as versatility of the instrument, it the VC -6155, a 100 MHz DSO. can cause a small amount of in- The V-212, which can be pur- convenience; a 20 V/div range chased for £320 +VAT, is the as fitted to many instruments dualtraceversionofthe would have helped solve this cheaper V-211. The accessories problem. A x 5 magnifier con- available include carrying trol extends the range of the Y - cases, rack mounting kits, and amplifiers to1 mV/div, and, in - viewinghoods.High -quality The packaging of the V-212 probes are also available, but at Fig. 1. Hitachi Type V212 oscilloscope takes into account the instru-

Table 1. Specification

ELECTRICAL CHARACTERISTICS: - Protection class 1. Line voltage: - 110,120,220,240 VAC ± 10%, Externally adjustable. Power 30 Watts. Line frequency 50,60,400 Hz TIMEBASE Deflection factor 0.2 psecidiv...0.2 sec/div ± 3% with 1/2/5 MECHANICAL CONSTRUCTION divisions. Dimensions: -W 310 mm, H 130 mm, D 370 mm Expansion x 10, extends max. timebase speed to 20 nsec/div; Housing: - aluminium sheet expansion error ± 2% extra. Weight: - approx. 6.5 kg Uncalibrated control full cw extends range to 0.5 sec/div.

Y AMPLIFIER ETC. TRIGGERING Operating modes: - Trigger modes: - Auto (bright line), Normal, active TV (line and CH 1 alone. frame) sync. CH 2 alone or inverted Trigger coupling: - AC only. alternate or chopped (250 kHz) CH 1/CH 2. Trigger sources: - CH 1, CH 2, Alternate Line, Ext. CH 1 ± CH 2. Triggering slope: - positive or negative, switchable. Frequency range 0...20 MHz ( -3 dB). Decreases to 7 MHz at Triggering sensitivity: - Internal 1.5 div at 20 MHz, External 1 mV. 800 mV at 20 MHz, Normal mode. Risetime 17.5 nsec. Deflection factor 10 steps: 5 mVidiv... 5 V/div ± 3% extends MISCELLANEOUS to 1 mV/div; by x 5 control, increases error by 2%. Min sensi- CRT -make Toshiba, measuring screen 100 x 80 mm, tivity 12.5 V/div; variable control; fully anti cw. accelerating voltage 2 kV; beam rotation by front panel Input coupling AC, DC or Gnd. adjustment. Input impedance 1 MQ!25 pF; Max input voltage 300 V (peak Compensation signal for divider probe; amplitude approx. including DC voltage), or 500 Vp-p AC at 1 kHz or less. 0.5 Vpp (± 3%), frequency 1 kHz. Z modulation 5 Vp-p noticeable modulation; Max input voltage X -Y MODE 30 V (DC r peak AC). CH 1 X-axis, CH 2 Y-axis. X Bandwidth DC to at least 500 kHz. CH 1 output at least 20 mV/div to 5 MHz. Less than 3° phase shift at 50 kHz. Covered by 2 year warranty. EE December 1937 ment's very compact design, period making instant measure- and the cardboard box in which ments easier. itis packed is, therefore, not The vertical modes of the V-212 much bigger than the instru- are fairly standard, including mentifself,whichisheld alternate and chopped securely in place with poly- (250 kHz) modes for dual trace. styrene cutouts. On inspection, operation. Only one channel (2) the Hitachi turned out to be a of the V-212 is invertable for sub- relativelysmallat 310 mm traction purposes, this being (W) x 130 mm(H) x 370 mm(D): implemented, as are some of theabsenceofthenormal the other functions, by pulling swivel stand adds to its com- an associated control (in this pactness. A small one -position case CH 2 position) to its out stand is fitted to the underside position. This does have advan- of the instrument to facilitate tages in that it helps provide an tilting, and for those who re- uncluttered layout, but it also quire the scope to be easily means that when this 'second- portable thereis a carrying Fig. 2. Close-up of V212 controls ary' function is operated, itis strap on one of the sidepanels. very easy to offset the 'primary' One advantage of the small Table2. function from its original value. stand is that it can easily be Triggering on the Hitachi is of a tftS3L, $414- VS,I. E.-&-_-,--.1 tucked under the scope, thus CATEGORY f.tory f.ture I c...., ao.c veryhighstandard,incor- malting the stacking of other TRIGGER PAU-RIES x porating the unsual feature of TRIGGER PERFORMANCE x pieces of equipment above or CRT IIMONTP.ESS x an alternate channel triggering CRT FOCLISiNS below the scope possible. The Y AMP PERFORMANCE x mode. This permits stable, fully UiTERNAL CONSTRUCTION x V-212 is supplied with a good E7CTERN..L CONSTRUCRON x triggered tracesto be pro- length of mains lead, connect- OVERALL SPECIFICATION duced ineitherdualtrace EASE OF USE x ing to the scope via a standard MAKUAL x mode from two non -synchron- IEC socket. Power consump- XY PULPORMANCE ized sources, as each channel is tion is low: only 30 W at 240 V. triggered independently. This Unusually, the scope isalso is invaluable for taking equipped with a vertical signal TABLE EXPLANATION measurementswheremore out BNC socket, which pro- than one signal source is being vides at least 20 mV/div into TRIGGER FACILITIES-The triggering facilities offered by the used within a circuit, and is also 50 Q. scope,eg alternate triggering, TV sync, auto trigger, etc. helpful for single trace The specifications are shown in measurements,enablingthe Table 1. From these it can be TRIGGER PERFORMANCE-Is an indication of how well and stable display of either channel easily the scope triaaers on a wide variety of waveforms, as well seen that the maximum Y ampli- without having to manually alter fier sensitivity is an excellent the maximum triggering frequency. the triggering channel. Active 1 mV/div, while the minimum is TV frame and line triggering CRT BRIGHTNESS-This is an indication of the brightness 5 V/div (calibrated) or approx. are also provided on the V-212, available on a fully triggered waveform at the maximum deflec- 12.5 V division (uncalibrated). making triggering on video tion speed. Note: some scopes have internal brightness presets, Whenmeasuringrelatively signals an easy task. The per- setting the maximum and minimum brightness; this is not taken formance of this was good, trig- deed, increases the versatility into account. of the Y -amplifiers throughout gering even at very low levels therange, providing acali- and over an acceptable range CRT FOCUSING-The standard of the focusing over the whole of line and frame frequencies. brated step outside the stan- range of deflection speeds and display modes. dard 1-2-5 sequence, i.e., in a 2- Two notable exceptions from the V -212's triggering facilities 4-10 sequence. This does how- Y -AMP PERFORMANCE-An indication of the maximum sensi- ever introduce a + 2% increase are HF and LF coupling, and tivity of the Y -amp, along with its performance across the band- although itis possible to get in Y amp error, bringing the width. total to a maximum of + 5%. Put- aroundthisproblem when tingthisinto perspective in these functions would normally INTERNAL CONSTRUCTION-This rating assesses the scope's be required by fine adjustment relation to, say, a waveform of internal construction, the main criterion being the quality of the typical total deflectionof of the triggering threshold, the PCBs and other components, the general neatness and layout necessary filters would have 40 mm, it may be that with even with a view to servicing and the mechanical robustness. a ± 5% Y amp error, a total made operation easier. Selec- tion of the triggering criteria is deflection error of more than EXTERNAL CONSTRUCTION-The strength and quality of the ± 2 mmisunlikelytobe made by a number of lever op- generated. In the x5 mode, materials used, along with the finish are among the criteria here. erated switches, making for however, the Y amps are limited fast, reliable and convenient op- OVERALL SPECIFICATION-This takes into account other eration of the scope. Trigger in bandwidth to 7 MHz (-3 dB). features which may be provided on the scope, such as triaaer On the whole I did not find this sensitivity was satisfactory at hold -off or a third channel, as well the general specification of 5 mm internally and 200 mV ex- restriction limiting as the full the scope. bandwidthisstillusableat ternally in the 20 Hz to 2 MHz 5 mV, at which sensitivity the Y range, increasing to 10 mm in- EASE OF USE-This assesses the general layout of the controls, ternally and 800 mV externally amps performed very well at and ease of use for a first time user, and not the ease of oper- their maximum bandwidth, be- in the 2 MHz to 20 MHz range. ing well insidetheir -3 dB ation of the range switches etc. Generally the triggering per- specified limit. The input amps formance was very good, with MANUAL-Takes into account the actual information included the alternate triggering being a also exhibited practically zero in the manual which is likely to be useful to the user. driftduringtheir warm up particular bonus: thisis nor- EE 34 December 1987 mally only found on models possible shock should be outer outsidethispricerange. A housing be removed. stable trace was produced in Not surprisingly, most of the nearlyallcases; the trigger semiconductors are manufac- threshold control did, however, tured by Hitachi themselves; prove to be sensitive and it was other components come from a very easy when pulling this variety of manufaturers and are control out (for triggering on fairly standard, ranging from the trailing edge of a signal) to miniature resistorsto the in- offset it outside the triggering dustry standard 78 and 79 series threshold,thuscausingthe monolithic fixed voltage timebase to free run, producing regulators. an unlocked trace. The 56 page manual contains a Maximum timebase speed is number of detailed sections, 200 ns/div; this is however ex- among which how to set up to tendable to a maximum deflec- scope initially, and a particu- tion speed of 20 ns/div (not larly good section on measur- 100 ns/divasstatedinthe ing procedures. There are no manual) by means of a x10 con- sections on calibration or ser- trol, although naturally this is at vicing, and the roughly A5 size the expense of trace intensity. Fig. 3. Internal view of V212 of the manual makes the circuit Speed selection is by means of diagrams small and andin a 19 -position rotary switch, the ditions. Robust feet/cable tion was generally good; theplace difficult to understand as minimum speeds being 0.2 s/ holders are featured on the rear large number of connections they are spread out over a num- div(calibrated)orroughly panel and protect the instru-maldng the mounting of all high ber of pages. There is also no 0.5 s/div (uncalibrated). On the ment to a large extent from any power dissipation components circuitdescription.Overall, maximum deflection speed of damage which may occur if, foron the subframe possible. The although containing some good 20 ns slight defocusing occurs example,theinstrumentis internal construction itself is ex- sections, the manual missed out towards the end of the trace,dropped while being carried.tremely compact: the two main on several important points and which is unfortunate, because IncontrasttomanyotherPCBs are mounted horizontally could have been accurately for the remaining speeds focus- scopes, all the controls have aabove one another at the frontsummarized in a considerably ing from the Toshiba tube is ex- very positive and fairly light ac- of the instrument. Unlike the Y shorter space. cellent for a 2 kV acceleration tion, making for easier, more amplifiers, the EHT section of voltage. Despite this, the per-precise operation. Some, how- the circuit is completely formance of the scope in this ever, notably the Y amplifiershrouded, thus helping to pre- good, many of fine controls, protrude a goodvent the build up of dust, as Conclusion its rivals not offering a 20 ns/div distance from the front panel,well as helping to prevent any The Hitachi V-212 is generally a sweep speed, although, asI makingaccidentaldamage have said, accurate measuring more likely in the event of a fall. over the last third of the trace at My only major criticism of the this speed is limited by the Hitachi, if it can be called that, 2 mm wide trace over this area. is the internal construction. The Other Hitachi scopes under £1000 The screen itself is filtered a main circuitry is mounted on light blue and has full gradua- two PCB's of equal size, but 20 MHz tions for risetime measurement. larger components, such as The V-212 is equipped with Z - voltageregulators,etc.,are V-222: As V-212 plus alternate magnify, swivel stand, scale illumi- modulation and CH 1vertical mounted on the chasses itself nation, uncal. indicators. Probes are also included. £395 +VAT. signal out facilities; the BNC for good heat dissipation. This connectors for both these func- wide variety of mounting points V-223: As V-222 plus sweep delay, 1 psec to 100 msec. £450 +VAT. tions are mounted on the back coupled with the three remain- panel. For noticeable intensity ing PCB's housing the tube V-225: As V-223 plus on -screen cursor measurement of voltage modulation a 5 V p -p signal is base, etc., necessitates the use and time difference. £550 +VAT. required, the input bandwidth of a large number of wire con- for this function going up to nections and links, giving the 40 MHz 2 MHz. The CH 1 output on the inside of the Hitachi an appear- other hand provides a buffered rence not dissimilar to one of V-422: As V-222 plus signal delay line,12 kV accelerating output from channel 1 which the company's tapes. All of the voltage. £580 +VAT. could be used todrive,for interconnections appear to be example, a counter/timer, thus of a very high quality, however, V-423 and V-425: As V-223 and V-225 respectively, but with in- providing an accurate readout and Ihave been assured by creased bandwidth. V-423: £650; V425: £695. of frequency, etc. Hitachi that the number of inter- Aluminium plays an importantconnections in no way affects 60 MHz part in the V -212's construction, the reliability of the scope. This both the outer housing and is proved by the fact that Hitachi V -650F: Similar to V-422 + dual timebase, trigger view, delay frame are manufactured fromoscilloscopes using the same multiplier: £780 +VAT. this, which contributes to theconstruction technique are ofscope's light weight of 6.5 kg.fered for hire by some of the PORTABLE Plasticis used for the frontelectronicequipmentrental fascia surround, and this couldcompanies, where reliability is V-209: 1 mV sensitivity 3.5" tube, lightweight miniature format, prove to be fragile, especiallyobviously at a premium. battery/mains, NiCd batteries included : £680+VAT. around the top corners if theIgnoring the number of inter- scope is used in rugged con -connections, internal construc- EE December 1987 well -thought out scope, withThe scope's smallsizealso wires, which could make ser-for most users who need a flex- some advanced features, and is makes it eminently suitable for vicing difficult. However, I amible scope for a wide variety of competitively priced at those users who include por- quite happy that they will in no tasks. 020 +VAT. Triggering is par-tability high on theirlistof way affectreliability. The ticularly good, having an alter-priorities. It does have one or manual is not really up to stan- nate triggering facility and thistwo minor shortcomings, such dard, despite its length, pro- The Hitachi V-212 was supplied coupled with the scope's ex- asitsinternalconstruction, viding only the initial 'set up' in-by Hitachi-Denshi (UK.) Ltd cellent CRT, which is one of thewhich, although of a fairly high formation, which admittedly is 13-14 Garrick Industrial Centre best 2 kV tubes I have seen,standard, does possess a large good. Summing up, the V-212 Garrick Road Hendon make it well worth looking at.numberof interconnecting should represent a good choice London NW9 9AP.

Crotech 3133 initslayout,with the CRT 165 mm. The weight of the 3133 ton is by means of a fixed lead, situated in the centre of the is also on the somewhat heavy i.e., no socket, which is a pity, The company of Crotech wasscope and the Y -amp and side at 8.5 kg. A three position since it is of only average length formedin 1981, andnow timebase/triggering controls swivel stand isfitted, which, so that in some cases it may be designs a wide range of testpositioned at either side of it. given the external graticule of necessary to extend its length. equipment from frequency Thisgivesthescopethe the tube, is just as well, since it As I have already mentioned, counters to signal generators.average size of 330 (W)x 395enables the scope to be pos- the3133incorporates some The 3133 is one of a range of six(D) mm, although the height is itioned to minimize the small rather unusual features, these in oscilloscopes manufactured bysomewhat higher than normal at parallax error. Mains connec- themain beingthepower the company. The range ex- supply, component comparator tends from the single trace 3031 and the more common trigger at£199tothe3339 which hold -off facility. features a 30 MHz bandwidth, The front panel layout is fully as well as a VDU mode, en- colour coded, and this should abling the scope to act as a make first time operation no monitor. at £570. The new 3133 problem, as well as contribu- is priced at a competitive £319. ting very significantly to the The 3133, which replaces the scope's ease of use. Most of the 3132, is unique in its price range functions are selected by a in that it incorporates a compo- series of push-button switches, nent comparator and a power which are arranged infour supply outlet in its design, and groups: CH 1input coupling; has a bandwidth of 25 MHz CH 2 input coupling, Display (-3 dB). Probes are also sup- mode; and trigger functions plied,but these are of the etc. While these provide an eas- 'crocodile clip' x 1design, so ilyidentifiable, and in some their usefulness for RF work is ways more flexible, method of limited. A x 1/ x10 probe may function selection, I found that be purchased as an optional ex- operation is perhaps slightly tra, along with a light hood and more time-consuming than the trolley. more usual 'slider' type The 3133 is somewhat unusual Fig. 4. The Crotech 3133 oscilloscope switches.

Table 3. Specification TIMEBASE Deflection factor 0.2 psecidiv. .0.5 seckliv ± 3% with 1/215 ELECTRICAL CHARACTERISTICS divisions. Line voltage: - 115,220,230,240 VAC, internally adjustable. Expansion x 5, extends max. timebase speed to 40 nsec/div (vari- Power 40 Watts. Line frequency: 27-65 Hz. able control fully anti cw), expansion error 2% extra; typical variable control error ± 2%. MECHANICAL CONSTRUCTION Dimensions: -W 330 mm, H 165 mm, D 395 mm TRIGGERING Housing: - aluminium sheet Trigger modes: - Auto (bright line); Normal; active TV (line and Weight: - approx. 8.5 kg frame) sync. Trigger coupling: - AC. DC, HF reject. Y AMPLIFIER ETC. Triager sources: - CH 1, CH 2, Line, Ext. Operating modes: - Triggering slope: - positive or negative, switchable. CH 1 alone. Triggering sensitivity: - Internal < 0.5 div at 25 MHz, External Inversion capability on CH 2 only. 1 V at 25 MHz, Auto mode. Alternate or chopped (120 kHz) CH 1/CH 2. CH 14- CH 2. MISCELLANEOUS Frequency range 0 . 25 MHz ( -3 dB). CRT-make NEC, 13 cm front faced round tube (viewing area Risetime < 14 nsec. approx. 100 x 80 mm); accelerating voltage 2 kV, beam rotation Deflection factor 12 steps; 2 mVidiv . 10 Nhcliv ± 3%; no vari- by front panel adjustment_ able attenuation controls. Compensation signal for divider probe, amplitude approx. 0,2 Vpp Input coupling AC, DC or Gnd. (-L- 3%), frequency 1 kHz. Input impedance 1 MQ/25 pF; Max input voltage 400 V (DC 4. Z modulation 20 Vp-p for complete blanking (-). peak AC). Power Supply: 5 V at1 Amp, 4-i -12 V floating at 200 mA continuous. X -Y MODE Component Comparator: - test voltage 8.6 V r.m.s., test current CH 1 Y-axis, CH 2 X-axis. X Bandwidth DC to1 MHz ( -3 dB). 28 mA max; line frequency = test frequency. Phase shift at 50 kHz 3°. Covered by 2 year 'Blue Chip' warranty. EE 36 December 1987 The Y -amplifiers,which are control, when fully clockwise, positioned to the left of the adds about 2% to the error. A tube, surprisingly have a band- x 5 control is provided, which width of 25 MHz: 5 MHz more increases the maximum deflec- than the 20 MHz offered by its tion speed to 40 nsec/div and directcompetitors.Perform- brings the maximum error at ance of the Y -amps is certainly this speed to approximately 7%, good,meetingthe25 MHz which I found acceptable for all bandwidth well inside its -3 dB tests carried out on the scope. limit. The 2 mV/div maximum Y - The maximum sweep speed of ampsensitivityiseffective 40 nsec/div gives a 1 division across the whole bandwidth, horizontalresolutionfora allowingaccuratemeasure- 25 MHz sine wave and should ment of low amplitude RF be enough for most purposes. signals. This range extends up The 3133is one of the few to a useful 10 V/div. I found cali- scopes which still use an exter- bration accuracy on all of these nal graticule CRT. On the 3133, ranges very good, and well parallaxerroriskepttoa within the quoted ± 3%. It is a minimum bystickingthe pity,however,thatboth Y - Fig. 5. Internal view of 3133 (right-hand) graticule template directly onto amplifiers have no variable con- the CRT, and, although a small trol. This among other things Trigger hold -off facilitates Normal and Auto modes areparallax error is obviously still makes accurate risetime stable triggering on complexalso provided, making trigger-present, I found that the extra measurements difficult, unless and irregular waveforms, and as ing effective across a widemeasuring error incurred when the deflection amplitude of the such is useful for displaying, for range of signals. Alternate, ortaking measurements is practi- signalmatchesthatofthe example, complex pulse trains Verticaltriggering,isnot acally zero, if the screen is view- risetime graticule. Both Y -amps in digital work over a wide feature of the scope, and conse-ed from a constant angle. The have a 14 ns risetime to accom- range of timebase speeds. The quently non -synchronizedexternal graticule does, how- modate their wider than usual 3133's hold -offfacility copedwaveforms cannot be stablyever, slightly obscure the trace bandwidth and this does, of with a wide variety of timebase displayed on both traces. along its markings to a small ex- course, help in giving more ac- speeds and waveforms, ranging Triggering sensitivityis very tent,andinsome circum- curate high frequency pulse from a simple double pulse to a good, typically being 2 mm up -stances it may be necessary to deflection representations than complex pulse train. Other trig- to 25 MHz internally, which isslightly alter the viewing angle themorecommon 17.5 ns gering functions include thewell inside the 0.5 div deflec-to clearly observe the whole of risetime. This reduced risetime more standard HF reject and TV tion quoted, or approximatelya low intensity trace. The 2 kV is largely due to the use of synchronization. Triggering 700 mVp-pexternally,againCRT itself is round and because faster FETs in the input stage performance is good for thewell inside the quoted 1 Vp-p.of this the trace cannot be ob- and in my view is well worth the vastmajorityof waveforms.To obtain these sort of sen-served at the corners of the trouble, not only having the ad- When the scope isin auto sitivities,fairly critical adjust-viewing screen. However, vantages outlined above, but mode and the TV frame sync is ment of the triggeringunder normal conditions, this in also that at 20 MHz the attenua- in operation, however, it is diffi- threshold is, however, required,no way affects the measuring tion is way below the -3 dB cult to lock on to the frame sync althoughtriggeringonthe capability of the instrument, as level, enabling more accurate pulses during a steady videoquoted sensitivities is more eas- most measurements are taken vertical measurements to be signal; a changing video signalily accomplished. at or around the centre of the made across the whole upper with a low signal content makesTimebase speeds range from screen. It may, however, slightly bandwidth. thisnexttoimpossible. No0.2 secs/divto0.5 iisecs/div; affectdualtraceoperation, The display modes on the 3133 problems were encountered inthe maximum speed being in-causing a small adjustment in are fairly standard, with the ex- the line sync mode and reliablecreased to 200 nsec/div by the waveform amplitude or position ceptionthatinsingletrace TV (both frame and line) trig-use of a variable control. Cali- on,forexample,apulse mode only CH 1can be dis- gering was present in Normalbration accuracy of the wavetrain, where viewing of the played, instead of the more mode. AC and DC coupling andtimebase is ± 3%, the variable initialleadingedgecould usual switchable CH 1/CH 2 op- otherwise be partly obscured. tion.Thisiscertainly not a Automatic focusing is not incor- major setback, but it can entail porated, and consequently a a certain amount of lead swap- small adjustment is necessary ping, or trace repositioning, if, when, for example, changing for example, it is necessary to deflection speeds from display a signal connected to 50 msec/div to 40 nsec/div in CH 2 for a full 8 cm vertical order to maintain the optimum deflection amplitude. A 1 kHz focus of the trace. The focusing 200 mV (±2%)p -p divider of the CRT at low to medium in- probecompensationsquare tensities is quite good, although wave output is provided. athigherintensity'sslight An ever increasingly popular defocussing did occur, feature is the trigger hold -off fa- although with the good cility, which is now finding its brightness available this is not way into the 'under £350' price surprising.Despitethis,the bracket. This, along with the in- tube'sperformanceonthe crease in bandwidthand focusing side does not quite slimline appearence, is one of match that given by some of the the main differences between better 2 kV internal graticule, the new 3133 and the older 3132. Fig. 6. Internal view of 3133 (left-hand) rectangular tubes. The CRT is EE December 1987 protected byadeep blue Other Crotech scopes Table4. plastic faceplate and is DUAL TRACE mounted in a bezel which also 3132-Preceding model to 3133, has camera mounting cut-outs. Untatis- Saris- Very CATEGORY factory factory Good Good Exceifent main differences 20 MHz band- The cost saving on the external TRIGGER FACILITIES width,notrigger hold -off, graticuletubeallowsextra TRIGGER PERFORMANCE . CRT BRIGHTNESS design. Currently £285 +VAT. features, such as the power CAT FOCUStfiG . Y AMP PERFORMANCE supply, to be incorporated. This INTERNAL cousreucnou 3337-30 MHz version of 3132, has three outputs which consist EXTERNAL CONSTRUCTION OVERALL SPECIFICATION - maindifferences 10 kVac- of a negative ground 5 V 1 Amp EASE OF USE x MANUAL celeration voltage, no compo- supply, suitable for driving TTL X/Y PERFORMANCE nent tester, signal delay. Cur- etc., and to floating ground out- rently £425 +VAT. puts which can be configured as ± 12 V (200 mA each), +24 V nents, allowing the user in most full circuit diagram, as well as 3339-Same as3337,except or -24 V supplies, suitable for cases to see their actual charac- diagrams of both mechanical VDU mode facility and the ad- driving a whole host of devices teristics. construction and PCB layout. dition of a component tester from op -amps to CMOS logic. Both the internal and external and power supply. Currently This facility should prove useful construction are of a very high £570 + VAT. to most users, even those who standard. Internal constructionConclusion already have their own power is based around a relativelyThe Crotech 3133's extra func- SINGLE TRACE supplies, mainly because in large number of PCBs, totalling tions and higher than normal3031 and 3032-singletrace, contrast to the average power seven in all. The timebase, Y - bandwidth turn what otherwise 20 MHz, component tester, 3031 supply, with perhaps 1 or 2 amplifiers, power supply, etc., would perhaps be an unexcep- 9.5 cm rectangular tube, 3036 supply rails,the 3133 has 3, are all mounted on differenttional scope into one which is 13 cm round tube.Currently already configured to supply boards, thus making servicing wellworthlookingat,es- £199 and£220respectively simultaneously both analogue greatly easier. All the PCBs are pecially when the price of £319 (both +VAT). and digital circuitry. For those silk screened with the various is taken into account. While the users who already have a com- component identificationCRT gives a reasonable per- Nextmonth,JulianNolan prehensive power supply, this numbers, and, where appro-formance, its external graticule reviews the Gould 0S300 and feature may be of more limited priate, their function. Both the can make accurate measure-the Grundig M020 oscillo- use, but I feel still worth while. attenuatorstageinthe Y - ments slightly more time con- scopes. Thecomponentcomparator amplifiers and the EHT section suming. It is probable, however, consistsoftwo component are fully shrouded, as is thethat the extra bandwidth and testers, which generally display CRT. The components them-functions offered by the 3133 a V -I type curve of the compo- selves come from a wide var-over its rivals will be worth this nent under test. The test signal iety of sources and all appear to to the many users who require a is an 8.6 V r.m.s.sine wave, be of a good quality. All internal scope which can be used for a which produces, for example, a wiring is neatly grouped, giv-large number of applications. sharp right angle for a typical ing the inside of the scope a The high standard of construc- diode, or ellipse for a capacitor. very neat appearance. External tion is also one of the 3133's Although it does not provideconstruction of the scope is to assets. The 3133 is particularly any accurate information as tothe same high standard, being suited to new users of scopes, the component's value, it doesalmost completely aluminium. asitisparticularly easy to provide a very clear indicationThis also includes, unusually, operate and it is supplied with of whether the component isthe front panel, which is silk two good manuals. To sum up, operational, if it is, for example, screened with the appropriatethe 3133 certainly represents 'leaky'. Component com-markings. None of the front value for money, offering as it parison is also possible with the panel controls extends beyond does a number of useful extra 3133 two testers,enabling athe display bezel, which further functions and a reasonable per- known good device to be ac-increases the robustness of the formance, while maintaining a curately compared with otherscope. With the construction in very high standard of construc- examples. It is also possible tomind,itis not surprising totion. If you require a versatile compare complete circuits withlearn that among the users ofscope, with a wide range of this technique, each circuit ef-the3133'spredecessor,the features along with good con- fectively having its own 3132, are British Nuclear Fuels, struction quality, I can certainly 'signature'. Initially, I was a little GEC, UK AEA and several large recommend it. sceptical of the component tes- industrial companies. I havebeeninformedby ter, mainly because I was un- A comprehensive manual and a Crotech that they intend to im- sure if its usefulness, in view of book entitled Getting The Bestprove the TV triggering per- the fact that the vast majority ofFrom Your Scope are included formance of the 3133; the review scope users possess a mul-with the 3133. Both are verymodel was a pre -production timeter. This opinion was, how-good, the manual covering in- prototype. ever, quickly changed by theitial setting up, servicing andThe Crotech 3133 was supplied component tester, which calibration,whilethebookby Crotech Instruments Ltd., 2, proved to provide a quick anddeals with a wide range of ap- Stephenson Road, St. Ives, Hun- veryclear method of both plications, including TV servic- tington, Cambridgeshire PEI7 testing and comparing compo-ing. The manual also includes a 4WJ. Tel. (0480) 301818

LOOK OUT FOR OUR SPECIAL OFFER OF THE 3133 IN NEXT MONTH'S ISSUE! EE 38 December 1987 Computer network design & tiveness. stalledwithin them. The EVENTS protocols Copies of the 'Call for papers seminar will take place on 1-2 8-11 Paris (in French) and Exhibition Information' may December at the Heathrow Pen- IEE meetings Integratedvoice/datacom- be obtained fromtheIBC ta Hotel, London. munications & ISDN Secretariat The Institution Further information from ERA this month 15-18 Paris (in French) ofElectrical Engineers TechnologyLtd Cleeve

Fibre optic communications SavoyPlace LONDON Road LEATHERHEAD KT22 3Inter -satellite links and on- 15-18 London WC2R OBL Telephone 01-240 board optical techniques 7SA Telephone (0372) 374151. Computer & communications 1871. 3 Testing expert systems security 7 Practical implementation of 8-11 Stockholm (in Swedish) expert systems in industry Details from ICS Publishing Co. 7 The UK space programme Ltd 3 Swan Court Leather - 8 Third Inter- Silicon sensors give head KT22 8AD TelephoneSemicon microprocessors new eyes Free Linkline Number 0800 282 national and ears 35 or (0372) 3792U. Europa 88 9 When the chips are down... Conference on 11 Control of time delay Semicon '88 and its associated systems SEMITechnicalConference Image 11 Education in circuit theory Willbe held at the Zuspa Con- and design International vention Centre, Zurich, Processing and 14-17 Land mobile radio Switzerland, from 1 to 3 March 17 Using computers in quality Broadcasting 1988. its Applications control Further information from SEMI The Third International Con- Full details from The Institution Convention European Secretariat ference on Image Processing ofElectricalEngineers 1988 Cochrane Communications and itsApplications will be SavoyPlace LONDON Ltd CCL House 59 Fleet held at the University of War- WC2R OBL Telephone 01-240 The 'Call for papers and Exhi-Street LONDON EC4Y 1JU wick from 18 to 20 July 1988. 1871. bition Information'for IBC88 Telephone 01-353 8807. The conference is organized by has been issued. the IEE and aims to provide a Papers are invited for presen- forum for the exchange of new tation and discussion in the results in the area of image pro- ICS courses this IBC88technicalprogramme, cessing. Papers of a review which will cover all aspects ofSeminar on nature will also be presented. month broadcastengineeringand For the purpose oftocon- related topics, including lightning ference, images can be taken to Introduction to Datacomm & BroadcastingSatellites(DBS); protection include all types of multidimen- networks Encryption for Video; sound sional data, for example, infra- 1-4 London and data; enhanced and high - ERA Technologyis holding a red. visual, radar, and sonar. 8-11 Stockholm (in Swedish) definition television systems, as two-day seminar and exhibition Further information from The Implementing local area net- well asmulti -channel soundon lighting protection.Itwill Institution of Electrical works and special services. Emphasiscover not only the protection of Engineers Savoy Place 1-4Stockholm (in Swedish) will be on emerging tech-buildings, but also the elec-LONDON WC2R OBL Tele- 8-11 London nology and its likely cost effec- trical and electronic systems in- phone 01-240 1871.

CUMULATIVE INDEX 1987

Audio & music LCD VU meter 12 - 22 Limiter for guitars 7/8 -S42 Active phase -linear cross -over network 9-61 Linkwitz filters 4-36 AF waveform generator 6-32 Loudspeaker protection 7/8-S14 Biphaser 3-46 Low -noise microphone preamplifier 10 - 36 Buzzer driver 7/8-S2 MIDI signal redistribution 5- 20 Compressor 7/8-S6 MIDI split control 3- 31 Current corrected AF amplifier 7/8-S9Mobile studio unit 2-51 Digital audio selector 7/8-S9 Patch catcher 7/8-S47 Digital volume control 7/8-S31 Record -playback amplifier 10 - 44 Electronic potentiometers 4 -36 Simple preamplifier 7/8-S53 Feedback in loudspeakers 4-20 Single -chip 40 W amplifier 7/8 - S58 Headphone amplifier 7/8-S15SMD headphone amplifier 7/8-S41 Horn loading revisited 9-44Stereo indicator 7/8-S36 Integrated stereo amplifier 7/8-S12 Stereo VU meter 3-20 Intercom for motorcyclists 6-44Top-of-the:range preamplifier -3 1- 30 in supplement of construction projects. 39 EE December 1987 Valve preamplifier - 1 3 - 50 Domestic Valve preamplifier - 2 4 - 26 7 -digit code lock 7/8 -S34 Central heating control 7/8-S65 Computers & microprocessors Current monitor and alarm 7/8 -S23 Light sensitive trigger 7/8 - S49 4 -way DAC extension 7/8-S62 Mains failure alarm 7/8 - S4 4 -bit D -A converter 10 - 38Thermometer 7/8 - S35 16 Kbyte CMOS RAM for C64 9 - 67 Toilet pointer 7/8-S19 16 -key input for MSX micros 7/8-S17 32 Kbyte pseudo ROM 7/8 -S20 A -D converter for joysticks 7/8 - S30 Generators, oscillators and test equipment BASIC computer 11 - 24 Bidirectional serial - parallel converter.. 7/8 -S11 8 -channel voltage display 7/8 -S50 Bus direction add-on for MSX extensions 7/8 -S49 Autoranging digital multimeter 6 - 51 Communication program for C64 7/8-S28 Capacitance meter 5- 33 Discrete DAC 7/8 -S57 Digital sine -wave generator 2 - 24 Drive selector 7/8 -S27 Duty factor analyser 7/8 - S6 IEC -Centronics interface 10 - 32 Function generator 7/8 -S54 Level adaptor for analogue joysticks 7/8-S18 HC -based oscillators 7/8-S36 Light detector 7/8 - S8 HCU/HCT-based oscillator 7/8-S59 MIDI split control 3 - 31 High-level two-tone RF test generator 9 - 65 Morse code teaching program for Electron Multi -function frequency meter 12 - 46 & BBC computers 11 - 64 Pierce oscillator 7/8 -S35 MSX extensions - 4: Precision crystal oscillator 7/8 -S45 I/O and timer cartridge 1 - 53 Precision rectifier 7/8 -S 54 MSX extensions - 5: Preset extension for function generator.. 4-34 EPROM programmer (1) 3 - 37Spot sine -wave generator - 1 5- 28 MSX extensions - 5: Spot sine -wave generator - 2 6- 38 EPROM programmer (2) 4-52Two-tone RF test oscillator 9 - 65 ROM/RAM card for Electron Plus One . . . . 2 - 48 Variable Wien bridge oscillator 7;8-S63 Serial data converter 7/8 - S38VLF add-on unit for oscilloscopes 2- 38 Simple D -A converter 7/8-S13Wien bridge oscillator 7/8 -S44 Standard disk and MIDI interface for Atari ST 2- 20 Synchronization separator 7/8 - Informative articles Universal control for stepper motors 1 - 38 Universal EPROM emulator 9 - 5460 -metre wind turbine for Burgar Hill completed 6-58 Background to hollow -emitter technology 10 - 60 Design principles and ideas The birth of satellite communications 11 - 20 British Aerospace: 10 years in space 12 - 26 3 -phase power converter for induction Bursting the bubble myth 5-20 motors 12-64The compact disc 7/8 - 39 ATN Filmnet decoder 7/8- 56 Computer science's Holy Grail 11 - 56 Band -gap voltage reference 7/8-S22Cossor Radar -the first 50 years (1) 1 -47 Decoding satellite TV signals 5-49Cossor Radar -the first 50 years (2) 2-43 Decoupling in logic circuits 7/8 -S48 The desk -top supercomputer 10 - 59 Driver IC Type TDA7260 for class D The digital audio tape recorder 11 - 32 amplifiers 6-55Digital signal processing 1 - 58 Electronic potentiometers 4-23 Directory enquiry service in £80 million Field-effect optocoupler 2- 58 computer development 6- 24 Filters -theory and practice - 1 7/8 - 50 Electronmicroscopy comes to life 10 - 24 Filters-theory and practice - 2 9-39 The future belongs to the photon 1 -27 Filters - theory and practice- 3 10- 28 How does the human computer work? . 5-37 HC -based oscillators 7/8-S36 Information theory and encryption 12 - 62 HCU/HCT-based oscillator 7/8-S59The Inmos transputer and Occam 11 - 50 High -current switching regulator IC Its master's voice 2-22 for SMPSUs 10 - 22 Lasers: an overview 7/8 - 27 An introduction to DC power supplies. 5-54Local area networking 4 - 56 Linkwitz filters 4-36The MAC system 7/8- 32 Low -noise amplifier Type TDA7232 5-26The magnetic way to painless brain Low voltage drop regulators 7/8-S52stimulation 6-26 OpAmp-based current source 7/8-S26Measurement of ventricular distances . . . . 9-31 Passive infra -red detector Type PID-11 . . 3-24Mobile satcoms for the future 7/8 -19 Pierce oscillator 7/8-S35 Mobile telephone -via -satellite service from The positive impedance converter 10 - 54Marconi 6-59 Precise motor speed regulator chip 11 - 62Numbers and the machine 12 - 50 Printed resistors 6-36 Philosophiae Naturalis Principia Transmission lines for TTL circuits 7/8-S39 Mathematica 12 - 43

S = in supplement of construction projects. EE 40 December 1987 The razor edge of the excimer laser 2-36 Low voltage drop regulators 7/8 - S52 Remote control in astronomy 3-34Tunnel diode battery charger 7/8-S40 Research collaboration to boost IT 10- 58 RIMS: counting atoms 4-48 Robot arms with the versatility of humans 5-58 RF, infra -red & video Satellite TV reception: your questions answered 2-30 ATN Filmnet decoder 7/8 - 56 Schools' equipment for tomorrow's Decoding satellite TV signals 5- 49 scientists 4-57 Four-way aerial switch 7/8 - S46 Secondary breakdown in power transistors 4-31 High level passive DBM 7/8-S21 Single -chip microcontrollers 9-18 High level wideband RF preamplifier 7/8-S4 Software for the BBC computer -2: High level two-tone test generator 9- 65 the BBC Buggy 1 -60 Indoor unit for satellite TV reception - 3 1-20 Software for the BBC computer- 3: Interfacing Atari ST and MSX computers to PCB design 2-56 SCART/TTL colour monitors 6- 47 Software for the BBC computer -4: Long-range infra -red transceiver 11 - 36 analogue circuit design 3- 56 Morse filters 7/8 - S43 Solar power generation 7/8- 22 Multi -mode pP-controlled IF module 7/8 - S24 Speech recognition system from Marconi . 5-45 Passive infra -red detector Type PID-11. 3- 24 Stand-alone EPROM programmer from RF module for IDU 7/8-S10 Bohm 6-21 SCART adaptor for IBM PC 3 - 44 Stream encryption 9-28 SMA FM stereo receiver 9 - 51 Strechable concave mirrors 5-61 SSB adapter 10 - 46 Switch -mode power supplies 10 - 49 SSB receiver for 80 and 20 metres 11 - 52 Technologists look to Britain Switchable bandselector 7/8 - S64 in Europe's great Eureka project 10 -62 Synchronization separator 7/8 - S37 Test and measurement equipment- 1: Synthesizer for SW receiver 7/8-S61 dual -trace oscilloscopes (A) 12 - 32 Two-tone RF test oscillator 9- 65 Testing the instruments of tomorrow 9-22 A tidal generator for energy and jobs.. 9-34 The ultimate solid-state memory? 3-27 Corrections The UNIX operating system 11 - 46 Where electronic messages have the edge 4-44 16 Kbyte CMOS RAM for C64 10 - 70 Where students make their own chips 7/8 - 54 Active phase -linear cross -over network.. 11 - 61 World electronics market expanding at Analogue wattmeter 2 - 29 6- 7 percent 6-54 Computerscope 2-29; 6-37; 9-66 D -A converter for I/O bus 7/8- 57 Digital sine -wave generator 11 - 61 Miscellaneous Electronic balance 1 - 37 Facsimile interface 9 - 66 6 -way channel selector 7/8 -S19 Headphone amplifier 9 - 66 Auto focus for slide projector 7/8 - S26 High power AF amplifier 6- 37 Buzzer driver 7/8 - S22 Horn loading revisited 11 -70; 12- 63 Digital driver for R/C motors 12 - 56IDU for satellite TV reception - 3 2- 29

Display intensity control 7/8 - S9 Long-range infra -red transmitter -receiver. 12-63 Dimmer for inductive loads 11 - 59 Preset extension for function generator 10 -70 Facsimile interface 4- 39 Printed resistors 9 - 66 Flashing lights 7/8 - S53 Single -chip microcontrollers 10-70 Flashing rear light 7/8 -S29SSB receiver for 20 and 80 m 12-63 Halogen lamp dimmer 7/8-S55 Stream encryption 11 - 61 Long-range infra -red transceiver 11 - 36 Synthesizer for SW receiver 9- 66 Metal detector 5- 40 Toilet pointer 9 - 66 Section indication for model railway 7/8-S18 Top -of -the -range preamplifier 6-37 Selective calling in CB radios 6 - 29 True RMS meter 1- 37 Speed control for DC motors 7/8-S32Universal control for stepper motors. 2- 29; 7/8- 57 Speed control for R/C models 7/8 -S60 Timer for fixing bath 7/8-S8 Tracking window comparator 7/8-S51

Power supplies & ancillaries

Band -gap voltage reference 7/8 - S22 Current indicator for 723 7/8-S33 Current monitor and alarm 7/8 -S23 Digital voltage/current display 7/8 -S5 Dimmer for inductive loads 11 - 59 High -current switching regulator IC for SMPSUs 10 - 22 Loss -free supply protector 7/8 - S66

S = in supplement of construction projects. EE 42 December 1987 17Why do you buy Elektor Electronics? 19 Education in electronics:

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Please use this space for any further comments. E.c.be9.7 READERSHIP SURVEY Since our last readership survey three years ago, Elektor Electronics has undergone a number of changes, brought about in the main as a result of your responses to the questions asked then, and also to keep abreast of our fast changing electronics environment. To make sure we remain on the right track, we ask all of you to take a few minutes to answer the 20 questions here by ticking the relevant box and post the completed form to: Elektor Electronics Readership Survey FREEPOST TK756 1 Harlequin Avenue BRENTFORD MIDDLESEX TW8 8BR England No postage stamp is required if the form is posted in Great Britain or Northern Ireland.

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Tools (6) you read regularly 43 EE December 1987 PHILOSOPHIAE NATURALIS PRINCIPIA MATHEMATICA or MATHEMATICAL PRINCIPLES OF NATURAL PHILOSOPHY by ISAAC NEWTON 1687 -A TERCENTENARY CELEBRATION 1987

by Dr. T.R. Carson, University of St. Andrews, Department of Physics & Astronomy.

Isaac Newton was born on 25 plete mechanistic philosophy. December 1642 in the manor - Due to the death of his father houseatWoolsthorpe,near two months before his birth, Grantham,Lincolnshire. He Newton spent his early years died on 20 March 1727 at Ken- witlihis maternal grandmother singon, London and was buried inWoolsthorpe.In1654 he in Westminster Abbey. Thus he entered the grammar school in lived under seven monarchs, as Grantham, but left in 1656 to well as two protectors, in what help manage the family farm, can surely be described as an returning to school in 1660 to age of revolution. Against this prepareforcollegefor he politically turbulent back- showed a remarkable precocity ground the world of learning inmathematics.In 1661he was undergoing, after a simi- matriculated at Trinity College, larly turbulentstart,its own Cambridge, where he became albeit quieter evolution. The an- a scholar in 1664 and graduated cient philosophy of Aristotle, B.A.in1665. He became a despite the efforts of Aquinas, fellow of Trinity College in 1667 had already sunk into decline. and in 1669 was elected Luca- OfthethreePhilosophies. sian professor of mathematics Metaphysical, Moral and in succession to Isaac Barrow Natural, the latter was poised whom he had impressed as "a for its most dramatic develop- very ingenious person" and "a ment.Man'splaceinthe man of exceptional ability and physicaluniverse had been remarkableskill".Hewas redefined by Copernicus and elected to fellowship of the Bruno. Bacon and Galileo had RoyalSocietyin 1672 and initiated a new science, based represented the university in on observation and mathemat- parliament in 1689 and in 1701, ically precise description, so SIR ISAAC NEWTON and was finally appointed to the immediatelyexemplifiedin post of Warden of the Mint in Kepler's three laws of planetary 1696 and Master in 1699. In 1703 motion. The most influential future development of natural series of events in space andNewton became president of philosopher of the seventeenth philosophythroughitsre- timesubjecttoquantitative the Royal Society, which office century was Descartes, whose duction of all reality to matter analysis based on premises ofhe retained forlife. He was attempttoconstruct anall - and motion. Newton's "Prin- cause and effect. Later on theknighted by Queen Anne on embracing philosophy of the cipia"represented thenext combination of Descartes' the occasion of her visit to Cam- world, failed even to resolve his step along this road. Matter was analytical, geometry andbridge in 1705. own conflict between reasoninvested with certain intrinsic Newton's differential and inte- During the years 1665-1666, at a and authority. Nevertheless it properties,bothactiveand gral calculus would becometime of enforced absence from had a lasting impact on the passive, while motion became a powerful tools in forging a com-Cambridge due to the plague, EE 44 December 1987 at Woolsthorpe, Newton made a in 1684 of Edmund Halley (soon number of advances in optics, assistant secretary of the Royal mathematics, mechanics and Society and editor of Philo- gravity. It was mainly with the sophical Transactions) to pose last three topics that the "Prin- the question, prompted by a cipia" would be later concern- discussion with Robert Hooke ed, but it was during this rural and Christopher Wren, as to retreat that the seeds of that what orbit a planet would follow bountiful harvest were sown. PHILOSOPFILE if attracted to the Sun by a force Newton himself wrote later "... varying inversely as the square fromKepler'sruleofthe NATURALIS of thedistance.Halley,im- periodical times of the planets pressed by Newton's im- [Kepler's third law]...I de- mediate answer, asked for the duced that the forces which PRINCI PIA proof, which Newton sent and keep the planets in their orbs was received by Halley with must be reciprocally as the such great satisfaction that he squares of their distances from MATHE MATICA visited Newton again to discuss the centres about which they the matter. He reported to the revolve: and thereby compared RoyalSocietythe"curious the force requisite to keep the Amore ys. NEWTON, Trim. Coll. Cantab. Sx. Mathefeos Proferforc Dicafianci, C Socicratis treatise, De Motu (On Motion)" Moon in her orb with the force which Newton had promised to of gravity at the surface of the send to the Society. This was re- earth, and found them answer IMPRIMATUR ceived in February 1685, pretty nearly. All this was in the S. PEPYS, Reg. Scc.PRJESES. Halley'sintentionbeingto two plague years of 1665 and yzlii5. ,656. secure the positionuntil 1666... for in those days I was in Newton could publish his work, the prime of my age for inven- as he was encouraged to do by tion and minded Mathematics LONDINI, Halley and by the Royal Society. and Philosophy more than at In April 1686 the Royal Society any time since ... between the juflit Set -ideas Regic ac Typh pfepLi .9rAtter. Profhr apud received a manuscript, in the years 1676 and 1677 I found the plums 8ibliopolas.ARM MDCLXXXVII. hand of namesake and ama- proposition that by a centrifugal nuensis Humprey Newton, of force reciprocally as the square 'I'LL PiL Or Tilt 11112 LblitOF Of TIIL "M.P. what Halley referred to as an of the distance a planet must "incomparable Treatise on Mo- revolve in an ellipse about the tion"entitled"Philosophiae centreofforceasfocus Naturalis Principia Math- [Kepler's first law]... and with a ematica" and dedicated to the radius drawn to that centre de- Society by Newton. This was in scribe areas proportional to the fact the first part of the "Prin- times [Kepler's second law]' cipia", comprising the "Defini- Christian Huygens had already tions", "Axioms or Laws of Mo- published in 1673 the rule of ILLUSTRISSIM/E tion" and "Book I - On the Mo- centrifugal force for uniform tion of Bodies", bearing the full circular motion. What Newton SOCIETATI REGALI title of the whole work. The did was to define the concepts Society resolved to have the of quantity of motion (momen- a Screnifilmo manuscriptprintedwithout tum) and force, and the laws delay at its own expense, and relating to them. He also made furthermore entrusted Halley to the conceptual move from cen- REGE CAROLO II supervisetheprinting.For trifugal to centripetal force and financialreasonstheRoyal generalized from the circle to A D Society shortly ordered that theellipse,havingalready Halley print itat his expense postulated the universality of PHILOSOPHIAM PROMOVENDAM which he engaged to do. In the gravitational force on the June1686 Newton informed falling terrestrial body and that Halley that he had intended the acting on the Moon and other UND A T "Principia" to consist of three heavenly bodies. The story of ET AusPICIIS books, of which the third would the apple falling from the tree concern thesystemofthe in the garden at Woolsthorpe POTENTISSIMI world, which he now proposed was told by William Stukely in MONAR_CFE. to suppress because "Philos- recountinghisconversations ophy is such an impertinently with Newton in 1726, and also litigious Lady that a man had as by Voltaire who obtained it from JACOBIII good be engaged in Law suits Newton's step -niece. The tree as have to do with her". Newton was cut down in 1820 but a por- F L O R E N T 1. realized that thetitleof the tion of the trunk may be seen in whole work would no longer thelibraryof the Royal Traaattim hunc humillimeD. D. D. be as appropriate, considered Astronomical Society in Bur- changingit,but on second lington House, Piccadilly. 7 S. NEIPTO N. thoughts retained the former ti- The events leading up to the tle to help the sale of the book. publication of the "Principia" Halley begged Newton "not began with the visit to Newton to...deprive us of your third 45 EE December 1987 book", adding thatitwould "Principia" hadgeneratedyoking gravity as a cause oftion Newton thus prepared the make the "Principia" accept- much excitement. Reactions to(changeof)motion, he was famous General Scholium con- able to "those thatwill call the book were quick to followmaking no statement regarding taining the sentence "...And themselves philosophers with- publication. Two reviews ap-the cause of gravity itself and thus much concerning God: to out mathematics, which are by peared in French (journal despermitted himself but one ref-discuss of whom from the ap- far the greaternumber". Sealants, Bibliotheque Univer-erence to God in the first edi-pearance of things, does cer- Newton deferred to Halley and selle) the latter being attributed tion. Richard Bentley, Master of tainly belong to Natural duly delivered to him "Book II to John Locke, one in Latin (ActaTrinity College, in his Robert Philosophy...". Herein toois - On the Motion of Bodies in Eruditorum), and one in English.Boyle Lectures (1692), noted that found the famous declaration Resisting Media" in March 1687 (Philosophical Transactions) bythe dispositions of the planets ...hypotheses non fingo... (I and "Book III - On the System Halley. Readers were left in norelative to the Sun were criticalframe no hypotheses)", which of the World" in April 1687. On doubt as to the scope and scale forthesustenanceoflife must be taken only in the con- 5 July1687 Halley wroteto of Newton's achievement. thereon, leading him to text of the cause of gravity, for Newton that he had "at length Newton's work appealed par-"discern the tokens of Wisdom Newton framed many hypoth- brought your book to an end, ticularly to mathematicians like in the placing of our Earth".eses. The third edition (1726) and hope it will please you". James Gregory (St Andrews and George Berkeley,Bishopof was prepared for Newton by Halley had written a latin ode, Edinburgh) and his nephew Cloyne, attacked Newton's con- Henry Pemberton who also, a dedicatedtoNewton,with David Gregory (Edinburgh andcepts of absolute space, absol-week after Newton's death, an- which he prefaced the work. In Oxford). Perhaps the first con- ute time and absolute motion as nounced a translation of the his own preface Newton paid a tinental student of Newton wasinadmissible since they enter- "Principia".This was never glowing tributeto the assist- NicolasFatio deDuillier,a tained "something besides God published and the first English ance which Halley had given Genevese mathematician whowhich is eternal, uncreated, in- translation was that of Andrew him. The title page bore the was instrumental in spreading finite,indivisible, unmutable". Motte in1729. Fatio was the "imprimatur" of Samuel Pepys, newsofthe"Principia"to Joseph Addison too upheld the authoroftheepigramon President of the Royal Society. Huygens in Holland and tothinking of Descartes, although Newton's tomb: "Sibi gratulen- The number of copies printed Leibnitz, otherwise known forboth Berkeley and Addisontur Mortales, Tale tantumque isunknown buthas been his controversy with Newton re-would later publish defences ofextitisse Humani Generis estimated as high as four hun- garding the calculus, in the Newtonian philosophy. Decus (Let mortals rejoice that dred. Newton received twenty Germany. An early casualty wasLeibnitz considered that gravity there has existed such and so forhimselfandfortyfor Descartes' philosophy, particu-"without any mechanism... or great an ornament of the human disposal through booksellers. larly as it applied to mechanics, by a law of God... without race)".Amongstthemany The price to the trade was six including his theory of vorticesusing any intelligible means, tributesthathave been ac- shillings in sheets, reduced to relatingtocelestialmotions. ...a senseless occult qual-cordedNewton's"magnum five shillings for cash, but nineHowever, to Newton the con-ity...". Roger Cotes (first Plu- opus" few are as generous as shillings leatherbound and let- cept of action at a distance with- mian Professor of Astronomy), that of Laplace in referring to tered! out mediation was an absurdity, editor of the second edition the causes "which News, emanating from Halleya point of some importance (1713) of"Principia"underassure the "Principia" a pre- andJohnFlamsteed (first when considering the later rev- Bentley's supervision, advised eminence above all the other Astronomer Royal), of the im-olution due to Einstein. Newton Newton to counter the criticism productions of the human in- pending appearanceofthealso made it clear that while in - of Leibnitz. For the second edi- tellect".

James C.Smith Esq, CEng, FLEE, Deputy Chairman, The company'shomeentertain- PEOPLE FLEE, Chairman, Eastern Elec- Electricity Council. ment's division. tricity Board. British Telecomhave an- Science, Education & Tech- nounced the appointment ofDivisional Chairmen Andrew Trollope has been ap- Dr Sydney O'Hara as Managing nology Division pointed Export Sales Manager Director of its British Telecom Derek R. Edwards Esq, Electronics Division BSc(Eng), CEng, FLEE, Consul- at ElectronicBrokers, the Enterprises (BTE) Division. Dr John R. Forrest, MA, DPhil, Prior to his appointment, Dr tant Engineer. specialist supplier of test and FEng, FIFE, Director of Engin- measuring O'Hara was Director, Products instrumentsand eering,IndependentBroad- second -user DEC computer and Services, in BT's UK Com- casting Authority. equipment. munications Division. Mr Alan Nicholson, BSc, CEng, MIMechE, has been appointed Computing & Control Division Marketing and Sales Director of Professor Bhalchandra V. Jaya - British Aerospace Naval andIn a move to meet the growing On 1 October last, the following want, PhD, DSc, CEng, FLEE, Electronic Systems Division. demand for its PC local area took office at the IEE for the School of Engineering and Ap- networkingproducts, 1987/88 session. plied 3Com Science,Universityof has appointed Paul Trowbridge Sussex. President Mr Tony Aspras has been ap-to head up its newly estab- lishedProduct Professor Eric Ash, CBE, PhD, Power Division pointed Sales Director of Syfer Consultancy Group. FEng, FLEE, FRS, Rector, Im- Kenneth M. Odell Esq, OBE, Technology Ltd, the wholly UK perial College of Science and BSc(Eng), ACGI, CEng, FLEE, owned manufacturer of multi - Technology. Engineering Director, Balfourlayer ceramic capacitors. Beatty Ltd. Deputy Presidents Dr T. Bryce McCrirrick, CBE, Management & Design Div- Carole Whittaker has joined FEng, FLEE, formerly Director ision Grundig International as of Engineering, BBC. David G Jefferies Esq, CEng, MarketingManagerinthe EE 46 December 1987 MULTI -FUNCTION FREQUENCY METER

An advanced, versatile and user -configurable testinstrument capable of accurate measurement of frequency,frequency ratio and time interval. In addition to all this, itcan be used as a period and event counter.

The multi -function test instru- S2 isusedfor checking ment described here is based whether the internal oscillator on the 8 -digit counter/timer IC works, but not for veryfing the Type ICM7226B from Intersil frequencyofoscillation.It (GE/RCA). This chip combines should be noted that input B is all the functions expected from only used for measuring fre- a good and versatile counter, quency ratios and time inter- and requires very few external vals.The frequencyofthe components. The chip handles signal applied to input A should frequency measurement from be higher than that applied to B. DC to 10 MHz, period measure- Similarly, the pulse transition on ment from 0.5 us to 10 s, unit input A should occur before counting up to 10 million events, that on input B. frequency ratio measurement, The protective networks fitted and time interval measurement. at the inputs of Ns and Nt The inputs of the proposed in- enableapplyingalternating strument can accept a wide The counter. IC3, has an on -above options on the frequencyvoltages as well as CMOS or chip timebase oscillator which range of alternating (analogue) TTL (digital) pulses. For small voltagesas operates at10 MHz (Xi).Itis wellasdigital when the relevant function is alternating voltages applied via pulses at TTL or CMOS levels. possible to use a 1 MHz quartz not required. Itis, of course, crystal provided Ss is closed. CI -C2, diodes D: -D2 or D3 -D4 also possible to replace the do not have a limiting effect, so Similarly, S7 makes it possible switches with wire links for per- that inverters Ns -Ns operate as toapply anexternal clock manent operation in a particular amplifiers. When the input am- Circuit description signal of 100 kHz or more to pin mode. 33. When switch S5 is closed, plitude is greater than about The circuit diagram of the fre- The maximum input frequency 2 Vpp, the inverters operate as quency meter is given in Fig. 1. thepositionof the decimal applied to input A of the instru- point on the display is con- buffers. Limiting of the input It would be beyond the scope ment is 10 MHz in the frequencysignal takes place when the in- trolled externally via the of this article to give a detailed and unit count modes, and put signal at the digital inputs is description of the internal oper- respective input, pin 20. The 2 MHz in the other modes. The lower than -0.6 V or higher decimal point can thus be pos- ation of the ICM7226B, and the counter modes and functions than +5.6 V. This means that AC itionedas requiredforthe following is, therefore,an that can be selected with the coupledinputvoltagesare prescaler used. Switches Ss -S7- outline of the simple peripheral RANGE switch,Sta-b, and the clipped to about 6 Vpp. The in- circuitry needed to obtain a58 and the associated diodes, FUNCTION switch. Sza-b, are sum- Ds -Dr -Da, are intended for the put sensitivity stated in the cir- complete instrument. A marized in Table 1. Position 6 of cuit diagram is an average and prescaler for extending the in- frequency dependentvalue. put frequency range to 1.2 GHz When the Type 74HCTO4 in will be discussed in a forth- Table 1 position IC2 (Ns ...Nio incl.) is coming issue of Elektor Elec- replaced with a 74HCU04, the tronics. Switch Sz: FUNCTION input sensitivity increases by a TheICM7226Bhasinternal Position Function factor 5 to 10. timebase circuitry, display 1 (K1) frequency (fA) The circuit around N7.. .N10 decoders, segment and digit 2(K8) period (TA) incl. and XOR gates N3 -N4 is drivers. The 8 -digit read-out is 3(K2) frequency ratio (fAlfa; ft. > fa) used for measuring time inter- composed of common cathode 4(K5) time interval (tA-te) vals, i.e., the period that lapses LED displays multiplexedat 5(K4) unit counter between the positive edges of 500 Hz and a duty factor of 0.122 i 6(K3) oscillator test the signals applied to inputs A per digit. Leading (non -signifi- Switch S4: RANGE and B. A bistable internal to the cant) zeroes are blanked when ICM7226B is set and reset by PositionAccumulation time I cycle(s) the meter is set to frequency the pulse transitions at input A measurement in kHz or period 1(K1) 0.01 s / 1 cycle and B, respectively. When the measurement in us. LED D9 in- 2(K2) 0.1 s / 10 cycles bistableisset,the oscillator dicates an overflow condition, 3(K3) 1 s / 100 cycles pulses are internally fed to the 4(K4) 10 s / 1,000 cycles i.e., the counter is "full", and all counter input.Evidently, the digits read 9. longer the bistable remains set, 47 EE December 1987

C21

322 PM Yr, _ Ctil CO 5V 111-N4 = IC1 = 74HC(T)56 - 715_N10 =1C2 = 7411DOL IM' 19' 6 - EXT. 17.7.3-4 34 3F. 35 2 MC_ EAT. PUT 05C. 11444 - CS, T!C..3 5r.) D RV 5 Ill K1 K2 43 K3 ca is ra 5V 33 EXT. OSC EX- CSC S sa RE *Soa Nal K7 15 K7 C2 .5 25 EMI 34 23 A - fs'.1FF. 05C.41 0 EJ7T. CSC 1. 53Y 03 ti6 IC 3 Ra K2 cc 42 IC H72251 2 51. 0 .ma] A 711.-DNI35 a.Fa *1 A:0 0 Ela 22 5V min 147 24 0 23

22 C= ¶ 1 in 22 ice , 79 R12 $2.4 rs 522 51 P.5 23 1-1. I-Er ee____iE.5 FUNCTION NI OP 255 MT OolkS4 U10 N9 20 rz Pk". OS - \ K.3 01--D5 = 1H4165

C3 13 C5; l5411 ni

F SET LD1-LCS = H011070 0 0 MSS LSB LDS L07 LDS LDS LD4 LD3 LD2 LD1 0;30 01 20

;1 0U. 01 0c co0 012 L- U. U. U. R. C12 CIO Omm OP 01 45 OVERFLOW D10_013= 1144001 57334 .1

Fig. 1 Circuit diagram of the multi -function frequency meter. the more pulses are counted, on. The 3 push -buttons can be circuit diagram are fitted on asecurely and slighlyoff the and the higher the read-out on fitted on the counter'sfront single printedcircuit board, board to prevent sharp solder the display. Push-buttonPRDtE panel as suggested in Fig. 2. whose track layout and compo- points piercing the insulating is pressed before measuringThe power supply for the fre-nent mounting plan are shown materialand causingshort- the time interval for a single quency meter is of conventionalin Fig. 3. Commence the con- circuitswiththegrounded event. Inverters N io-Ns design, and requires no further struction with fitting all the wire metal can. It is recommended generate a brief pulse for chip detailing. links. Do not forget the 8 short to use good quality sockets for inputA; Ns -N7 aslightly ones underneath the displays! all integrated circuits. The dis- delayed pulse for input R The Electrolytic capacitorCl?is fit- plays are also fitted in 10 -way internal logic in the ICM722613 Construction ted at the track side of the sockets, made from terminal isthusprimedreadyfor Virtually all parts shown in the board. Make sure that it is fitted strips or 14 -way IC sockets. Use measuring the interval for one event, delimited by the positive edges of the pulses applied to 2 instrument input A and R Press- ingPRIMEis not required when these inputs are driven with a .1. 215 1. w:.3 Ola Vs, repetitivesignal, as thefirst .1 400 alternating signal states cause eIAN automatic Multi -function priming ofthe 0.42i111. PF.E. 0 Frequency Meter counter chip. SCaLE1 The read-out can is retained ("frozen") as long as the Hort) e ED switch,Ss, ispressed. The 0 counter's internal circuits-and PERT WAD Haut hence the read-out- can be cleared at all times by pressing theRESETkey, S. CapacitorC7 is connected in parallel withS3 to prevent hang-ups at power Fig. 2 Lay -out of the ready-made front panel foil for the frequency meter. EE 48 December 1987

Fig. 3 Track layout and component overlay of the PCB for building the frequency meter. Capacitor C12 is fitted AT THE TRACK SIDE. short lengths of strong wire towire, to minimize stray induct- ensure the correct height of the ance and capacitance.This displays above the board. LED measureeffectivelyprevents D9 isa high brilliance typeunwanted effects such as in- whose leads are lengthened determinateillumination of make its top is level with thedigits ("ghosting"). As already displays in the sockets. Voltage stated, function switches Ss-Si- regulator IC4 should beSa may not be required on the mounted with a heat -sink. Thefront panel of the instrument. In- RANGEandFUNCTIONswitches, puts A and B are made in S4 and S2, are soldered directflange -type or single hole BNC onto the board, or with shortsockets. Two more of these are lenghts of left over componentrequired when it is intended to The completed printed circuit board (prototype version). 49 EE December 1987 extend the frequency meter right-hand side of the display with the prescaler to be in- bezel.Thepositionofthe troduced. InputsEXT.osc, Ex -r. various controls and indicators DP,and output sum osc, can be is evident from Figs. 2 and 4. made in suitable sockets on the It is, of course, possible to use a Parts list Miscellaneous: rear panel of the enclosure. The ready-made mains adapter with St;Ss;Ss= push -to -make signal at our osc can be used 8 VAC output for powering the Resistors 5%): button. for setting the oscillatorfre- instrument. In many cases, this Rt;R4;Fl1 e= 330R Sz= 2 -pole 6 -way rotary switch quency to 10.000 MHz precisely is safer and less expensive than R2;R3;115;R7;Ra:fi to= 100K for PCB mounting.* with the aid of trimmer capaci- incorporating a mains trans- Re =150K S4= 4 or 6 -way rotary tor Cs. It is also possible to use former. When it is still intended Fis;Riz;Ria;Rt4=10K switch for PCB mounting: 1311=10M the signal for driving other cir-to furnish the frequency meter Se;S7;Se= miniature SPST cuits, provided theBUFt oscout- with its own, internal, mains switch (see text). put is fitted with a 10K resistor to supply, the mains socket and Xt = 10 MHz quartz qrystal. Capacitors: the +5 V rail. fuse (100 mA) should be fitted at T0220 style heat -sink for IC-i. CI;C2=1p; 63 V (non - Verobox enclosure Type The supply voltageforthe safelocations onto the rear electrolytic) 4775-1411. prescalerisavailableon 2panel of the enclosure. The C3=150n PCB Type 87666 (available soldering pins next to theMI mains transformer should be C4 = 1n0 through the Readers Services). DPinput. preferably an 8 V, 0.5 A type. Ce;C7;Ci o;011;C 3:C14; Front panel foil Type 87286F The completed PCB is mounted The current consumption of the Cte=100n (available through the Readers vertically in themoulded circuit is about 55 mA with all Ce:Ca = 39p Services). guides provided in the bottom displays blanked, and 175 mA Cs=40p trimmer Mains transformer 8 V; 0_5 A. C12=4700; 25 V plate of the Vero enclosure. The with all displays illuminated. 14 Mains entrance socket, fuse ready-made front panel foil for (100 mA), and DPDT switch. Semiconductors: Knobs for rotary switches. the frequency meter can be D'. .D5 incl. =1144148 BWC sockets as required. used as a template for drilling De;Dz:De= 1144148 (see text) the metal front panel provided Ds= high brilliance LED (red) Available from Universal with the enclosure. The shafts D to .013 incl. =IN4001 Semiconductor Devices Limited of the rotary switches, S2 and D14= red LED 17 Granville Court Si, are cut to size to enable fit- ICt=74HC86 or 74HCT86 Granville Road Homsey ting suitable knobs. The LED Reference: IC2 = 74HCUO4 or 74HCT04 London 144 4EP. Telephone: displays arefittedin a rec- 1C3=ICM7226BIJL or (01 384) 9420. Telex: 25157 tangular clearance cut in the Component Data Catalog 1987: ICM7226BIPL' usdco g. Fax: 01 348 9425. ICM7226A/B p. 14-80 ff. Intersil IC4=7805 front panel. The visibility of the LDI ...LDa incl.= common Switch with adjustable stop, read-out is enhanced by the GE/RCA International Limited cathode LED display e.g. Lorlin Type CK1045 (Cirkit semi -transparent bezel in the Beech House 373-399 Lon- HD11070 stock no. 53-21045). ready-madefrontpanelfoil. don Road Camberley Sur- TheOVERFLOWindicator, Ds, is reyGU153HR.Telephone: fitted immediately below the (0276) 685911. Fax: (0276) 685255. 4

_ 44- 47 5

TST V! 2.5 155 4 14 4 4 as 56, ca_s 4 4. 4 107 4- - - - 4 .7 4 = 4 4 4 87286

Fig. 4. Drilling diagram for the front panel. EE 50 December 1987 NUMBERS AND THE MACHINE

by C.H. Freeman

Computer science depends largely on the properties of real numbers. The correct use of these requires an understanding of the mathematic basis of the real number system. Unfortunately, many people shy away from anything mathematical, even if it has only to do with numbers. This article attempts to allay these misgivings.

Modern man counts in base ten, tion arising from Binary digiT). have 16 individual symbols in its It is at this point that octal and thatis,he uses the ten in- So, using the above expression, counting system and after go- hex become interesting. By col- dividual symbols 0, 1, 2,...,8, 9. a string of binary digits, such as ing through the symbols 0-9 we lectingadjacentbits into Obvious, you might say, but it 11001, can represent the run out! Mathematicians, when groups of four, we can write just hasn't always been so. Somedecimal number faced with problems such as one hex digit in place of each races have been known to these, invariably do the decent group. To illustrate, consider count in base 20 (by using their lx24 + 1x23 + Ox22 + thing - and cheat. In this case toes and fingers in arithmetical + Ox2' + lx2° = 25 the letters A -F are pressed into 59 = 111011 = 0011 1011 = operations) and the concept of service and the full counting = 3B (hex) zero itself is quite new; conse-and we can now see how any system runs 0, 1, 2, 3, 4, 5, 6, 7, 8, quently, the Romans, who had positive decimal integer can be 9, A, B, C, D, E, F. and it can be seen that hex no- no representation for zero, hadrepresented in binary, and also tation can act as a useful 'short- endless trouble with arithmetic. how totransformabinary hand' when writing long binary In general, an ri digit integer, number into its decimal equiva- Binary addition sequences. Note how we pad No, can be represented by lent. But what about translating Two binary numbers are added the number out with leading decimal into binary? What dotogether in the same way twozeroes in order to obtain two No = drSn + dn-1R11-1 we do then? The answer is, we decimal numbers are added4 bit groupings. A similar tech- +d,R1 + d°R° simplydivideourdecimal together: by adding together in-nique can be adopted using oc- repeatedly by 2, recording thedividual digits, paying due at- tal by gathering bits into groups Or remainder at each stage of the tentiontoanycarrydigits of three thus division.Theseriesofre- generated. As there are just 2 No= drRr mainders, when read 'from the digitsin the binary system, 59 = 111011 = 111 011 = 73 (octal) bottom up', form our binary thereare4possiblesums where ci1, d2, , dn are thenumber. Let's try an example, which can be formed. These decimal symbols in the coun- converting 229 into binary are ting system and R is the number Signed integer base we are working in. When 229=2 sumcarry representation we count in decimal, the sym- 114 remainder 1 0 + 0= 0 0 Sofar we have considered bols used are 0,1, 2, ,9 and 57 remainder 0 0 + 1= 0 binary representation of R, the base (or radix), is 10. Thus 28 remainder 1 1 + 0= 1 0 positiveintegers 1 + 1= 0 only. What we can represent, say, 50465 as 14 remainder 0 happens if we want our com- 7 remainder 0 3 remainder 1 Using this principle, we canputer to hold a negative in- 5x104 + Ox102 + 4x102 + teger? Our system has so far 6x10' + 5x10° 1 remainder 1 generateatableof binary numbers alongside theirmade no allowance for such 0 remainder 1 eventualities so what can be Now, althoughthissuitsus decimal equivalents.Partof done? Fortunately, three humans verynicely,digital thus 229 = 11100101. Check this such a table for a 4 bit binary is possibilities exist. They are systems do not use ten discrete for yourself by converting theshown in Table 1. values when representing number back into base 10. numbers; the engineering What we have just discovered TABLE 1. (a) sign -magnitude problems introduced in usingabout converting decimal to representation. such a system would be tooand from base two applies 23 22 2'2°DECIMAL HEX This is the simplest possible great. Instead we use base two, equally well to base 3, base 7, method and relies upon the fact 0000 0 0 more commonly referred to as base 9 or, in fact, any base you that computers hold numbers in 9 o0 1 1 1 binary. The binary system has care to name. Actually, two fixed length registers. These o o 1 0 2 2 just two decimal digits in its other bases, base 8 and base 16 00 1 1 3 3 registers are usually 4, 8, 16 or counting system: 0 and 1. Now, (known as octal and hexadeci- 0 1 00 4 4 32 bits in length, but the import- this is handy because a switch, mal respectively), are import- 0 1 0 1 5 ant fact is that their length is beitelectronic, mechanical, ant, but more of this later. For constant. If we have an n bit hydraulic, pneumatic etc., canthe moment, though, you may - - - register, we can use the most be either on or off and can thus well be wondering about base significant bit as an indicator (or 1 1 1 0 14 be made to represent a single 16(or hex asitisusually FLAG) to represent a positive or 1 1 1 1 15 F binary digit (or bit: the deriva- known). After all, base 16 will negative number. It is usual for MEE December 1987 this bit to be set (i.e.1) when toitstwos complement will two binaries, but it is far lessthen it actually is. To a person, representing a negative num- resultinallzeroes plus an simple to build circuitry whichperforming suchaprocess ber and reset(i.e.0) when overflow carry. If the system in can perform subtraction direct-seems quite alien, but com- representing a positive. The use ignores any digits in excess ly. This means that the process puter circuitry finds the pro- rest of the n-1 bits hold the ab- of n then the above equation ofsubtractingonebinarycess beautifully simple. And solute value of the number. The reduces to number from anotherisin- speakingofsimplicity,the greatest absolute value which variably reduced to two distinctworld of numbers is not limited can be held in such a register is RC = -Nr operations: forming the com-to the simple system of integers. 2n-1-1 so it follows that if a plement of the subtrahend, and We must now examine how we number is held in an n bit in other words, the radix com- 'then adding this complement tocan represent the system of register in this form plement represents the the minuend. This leaves us natural numbers in binary. negative of a number in the with the decision as to which range = 0 to ± (2n-1-1) same number of bits. complement to use: ones com- inclusive Computer circuitry can easilyplement or twos complement? form a twos complement by If we choose to use twos comp- The real world (b) diminished radix firstly inverting all the bits of the lement, we simply add and then complement. number (to obtain a ones com- discard any carry which mayIn our earlier look at binary For an n digit number N: inplement) and then simply ad- arise from the most significant numbers we saw how an n digit base R, we can form what isding 1to the least significantdigit. If we use the ones com- integer, No, in base R could be known as its diminished radixbit. For us mortals there exists plement, however, any suchrepresented in the following complement by applying the an easier method of translating carry must be added to the manner: formula a binary into its twos comple- least significantdigit.Ifthis ment. Starting with the leastgenerates further carry digits, No = dnRn + do -1 Rn-1 + DRC = (Rn-Nr)-1 significant bit, we copy all the they must be also added until + + diR1 + doh") bits in the number up to and in- no further carries are The name of the complement cluding the first occurrence ofgenerated.This end -around - We now extend this to enable depends upon thebasein one. The remaining bits are carry means that arithmetic per- us to represent any finite length which operations are being then inverted. Table 2 showsformed with the twos comple- real number using the follow- performed and takes the name comparative representations ment system is a much simpler ing representation: of the highest decimal digit in for a 4 bit register. Note that in business than all that mucking the system. Thus the DRC of a the case of twos complement aboutinones complement. No = dr.Rn + + chR' + decimal number is known as its representation Consequently,twoscomple- + &JP' + d -1 + + nines complement, whilst that ment is the method computers of a binary is referred to as its range = -(2n -I) to will normally use when ones complement. With the (2n -I -1) inclusive representingnegativenum- Now, when we use binary to above equation as a bers. Let's look at an example, represent such a number, we springboard, it is not difficult to andthe minimum negativesubtracting 13 from 42 to leave are using show that the ones complement number cannot be negated. 29: of any binary can be formed No = dnx2n dna' ÷ simply by inverting each bit, 42 = 101010 13 = 001101 + dox2° + d-ix2-1 + that is changing 1 to 0 and 0 to 29 = 011101 + d. -2x2-2 + 1. For example. Why bother? and it should be easy to see that If all this seems as if it is merelyOnes comp. of13 =110010, 0001 represents 1 someabstractmathematical +1 = twos comp. = 110011 we can hold a binary fraction in stuff, then let me assure you that aregister,usingthemost 1110 represents -1 it is not. All this maths has a very 101010 ÷ 110011 = 1011101 significant bit to represent 2-1, practical consideration in the etc. Thus in an n bit system the design of computer hardware. Discarding carry leaves greatest positive number will You see, it is easy to build cir- 011101 = 29 MSBI be held by only n- I of the bits. cuitry which can perform inver- Therefore, the greatest positive sion of a binary and addition ofThis looks more complicated 2-1 2-2 2-32- 4etc. number = 2n-1-1. The greatest negative will be represented by TABLE 2. a 1 in the most significant bit followed by n -1 zeroes. Hence REGISTER POSITIVE ONES TWOS SIGN HEX OCTAL range = 0 to ± (2n-1-1) BIT INTEGERS COMPLEMENT COMPLEMENT MAGNITUDE inclusive PATTERN 0111 7 +7 4-7 +7 7 7 0110 6 +6 +6 +6 6 6 (c) radix complement 0101 5 +5 +5 +5 5 5 representation. 0100 4 +4 +4 +4 4 4 3 +3 +3 +3 3 3 The radix complement of an n 0011 0010 2 +2 +2 +2 2 2 digit number Nr in base R can 0001 1 +1 +1 +1 1 1 be calculated using the equa- 0000 0 +0 +0 +0 0 0 tion 1111 15 -0 -1 -7 F 17 1110 14 -1 -2 -6 E 16 RC = Rn -Nr 1101 13 -2 -3 -5 D 15 1100 12 -3 -4 -4 C 14 and the radix complement of a 1011 11 -4 -5 -3 B 13 binary number is referred to as 1010 10 -5 -6 -2 A 12 its twos complement. It should 1001 9 -6 -7 -1 9 11 1000 8 -8 -0 8 10 be clear that adding a number -7 EE December 1987 Table 3 showsathree -bit - 0.750 x 2-8 = -6/2048 register holding binary frac- TABLE 3. tions in just such a way, along REGISTER SUM DECIMAL with the decimal equivalent of BIT PATTERN itscontents. This tablealso - 0.875 x 27 = -112 shows the method of converting 000 O+ 0+ 0 0.000 a binary fraction into a decimal 00 1 0 ÷0÷ 2 0.125 - 1.000 x 27 = -128 0 1 0 0 4- 2 +0 0.250 fraction. By inspection, it 0 1 1 0+ 2± 2 0.375 should also be easy to see that Notice that because of the twos 1 00 0, 0.500 such an n bit register can hold 2+ 0+ 1 0 1 2 0+ 2 0.625 complement method of storing values in the range 1 1 0 2+ 2+0 0.750 our mantissa thereare two 1 1 1 12 +2+2 0.875 numberswhichcannotbe 0.0 to (1.0 - negated: the minimum positive in steps of 2-n. real and the minimum negative Floating point Let's try and illustrate this by real. Before going any further, we'll representation considering afictional com-A 'proper' computer would, of take a look at how we convert puter holding numbers in two 4 course, use many more bits than Floatingpoint representation bit registers: decimal fractions into binary relies on thefactthatany 4 to represent numbers but the fractions. Decimal integers, as number in base R can be split principle is exactly the same as we saw earlier, are converted into two parts, its mantissa, M, thatoutlinedforour4bit into their binary equivalents by together with its corresponding example above. repeated division by two, re- exponent, E, and depicted as cording the remainder at each stage. Decimal fractions, on the MxRE SIGN 2-' 2-2 2-3 otherhand,arerepeatedly Range and multiplied by two.At each In decimal, of course, this cor- accuracy stage, the resulting integer part responds to the familiar ex- Itisclear,judging by the is separated from its fractional ponential notation (powers of example above, that there are part and forms a bit in the ten) we all know and love. If we somedecimalswhichcan resulting binary. The process is consider the binary number SIGN 4 2 1 never be represented exactly, better illustrated by example 101.1101 (for example) then it can for the reason that there simply than by words so let's convert be written in mantissa and ex-The mantissa, remember,is aren't enough bits available to 0.375 into binary: ponent form as normalized so it can take the bit fit the number in. For example, patterns (ignoring the sign bit 109 = 1101101 0.375 x 2 101.1101x21 or 10110.1x2-3 or and considering 2-'as the 0 + 0.750 x 2 0.1011101x 24 most significant bit) 109 = 0.1101101x27 1 + 0.50 x 2 1 + 0.0 process completed. The last notation is, in fact, the 111,110, 101, 100 corresponding But the binary equivalent is too 0.375 = 0.011 usual method of writing binaryto the decimals big to fit into our 4 bit mantissa. reals, with the most significant In cases such as these there are Try converting a few decimals setbitcoming immediately 0.875, 0.750, 0.625, 0.500 two options open. We can simp- into their binary equivalents, after the decimal point. Such a and for negative mantissas the ly 'chop off' (or TRUNCATE) the and then convert them back number issaid to be NOR- excess bits and store as into decimal again. You'll soon MALIZED. In point of fact this is possible range which can be get the hang of it! Now we know stored is almost exactly how computers 0.110x2 = 96 how to convert a decimal real do store real numbers within -1.000, -0.875, -0.75, -0.625 into a binary reallet's think their memories, as two distinct or we can ROUND the number about how we can store such a series of bits representing man-and we get the range for our up (or down accordingly) to number inside a computer. tissaandexponent.You've mantissa If we think of a binary number probably also noticed by now 0.111x2 = 112 as having two separate consti- that numbers stored in this way -1.0, - 0.875, -0.75, -0.625, tuents, an integer part and a will have the most significant bit 0, 0.5, 0.625, 0.75, 0.875 Whatever happens, it should be fractional part, then it would ofthemantissaapparently realizedthattherewillin- seem an obvious move to store redundant (as it appears it willThe exponent can takethe variably be a degree of error in such numbers in the following always be zero). This is no ac-range +7 to -8 in steps of 1, of computer arithmetic.Usually way: cident.Negative as well ascourse. The numbers we can such errors present no big positivemantissasandex-representinour'machine', problems and can be allowed M BITS N BITS ponents must be catered fortherefore, will be for. INTEGER FRACTIONAL and in such cases the mantissa As far as range is concerned, if PART PART is held in twos complement 0.875 x 27 = 112 a machine stores numbers as M form, the most significant bit bit mantissas and N bitex- leading us to suppose we canbeing taken as a signbit. 0.750 x 27 = 96 ponents, the greatest possible store numbers in steps of 2-N. Remember that such a bit will positive mantissa will be equal In fact, this is a very poor way to usually be set if the number it to storenumbers. When very representsisnegative,and large or very small values are reset if the mantissa is positive. 0.625 x 2-2 = 5/2048 0.111 ...111 represented in such a way, it is The exponent is also held in found that there can be vasttwos complement form (see 0.500x2-2 = 4/2048 and will be equal to 1-2-(m-0 amounts of 'wasted space. This below) is inevitable whenever such a 0 and the greatest possible expo- fixed point system is adopted SIGN MANTISSA SIGN EXPONENT nent will be given by 2N-1-1. and a much better bet is... BIT BIT - 0.625 x 2 -8 = -5/2048 So, EE December 1937 greatest positive number - Try and work out the largest diverse as spacecraft navigation Theauthorwouldliketo (1-2-'-'-'))x(2N-1 -1) andsmallestnegativereals to preparing and printing youracknowledge the help of Mr. G As far as the smallest positivewhich can be represented. So gas bill. The modern world is so Parkes,dept.of compute there you haveit! real is concerned, the mantissa Computer very heavily dependent upon science, University of Hull. fo, will equal 2-1 and the expo- arithmetic is not just so much computers thatitisdoubtful his assistance in the prepara- nent will be 2- '2"-j arcane theory, but is a whether it could function with- tion of this article. fascinating branch of mathemat- out their assistance. Love them Smallest positive number = ics: a branch which is in con- or loathe them, you've got to ad- -I) 2-I x2 -(2N stantdailyuseinfieldsas mit that we need them! NEW LITERATURE NEW LITERATURE

AVAILABLE SHORTLY 303 CIRCUITS ISBN 0 905705 26 2 Price: £7.95 303 CIRCUITS is the latest in Elektor Electronics' well -liked series of books for the electronics enthusiast, professional or amateur alike. Like its predecessors. it offers a comprehensive collection of practical ideas, concepts, and developments in the gamut of electronics. Unlike its predecessors, 303 CIRCUITS is arranged in 11 subject sections to make it easier for the reader to find that long -sought circuit. In well over 300 pages, 303 CIRCUITS offers 32 Audio and Hi-fi projects; 14 circuits for Cars & Bicycles; 43 Computer & Microprocessor circuits; 11 Electrophonics projects; 24 HF & VHF circuits; 16 circuits for a number of hobbies & pastimes; 54 projects for Home & Garden; 29 Power Supply circuits; 29 circuits for Test & Measurement equipment; 9 TV & Video projects; as well as 42 Design Ideas.

ELEKTOR ELECTRONICS 1 Harlequin Avenue Great West Road BRENTFORD TW8 9EW England Telephone 01-847 2618 Used test makes their Types 7061 and ting, as well as giving brief in- 7062 71/2 -digit DVMs the fastest formation on their range of test MAPLIN 1988 Equipment precisionvoltmetersonthe and measurement instrumentsCatalogue market, with transient capture isavailablefromAdvance Carston's new StockListof facilities superior to a digital Bryans Instruments Ltd 14- Maplin's 1988 Buyer's Guide to Used Test Equipment and Com- storage oscilloscope. Solartron 16 Wates Way MITCHAM Electronic Components is up in puter Products is now available Instruments Victoria Road Surrey CR4 41IR. size by 40 pages to 512. as com- from Carston Electronics Ltd FARNBOROUGH GU14 7PW. pared with the 1987 issue. Up 2-6 Queens Road TED- alsoisthe amount of infor- DINGTON Middlesex TINU mation packed onto each page, OLR. MIME -600 with the opportunity taken, for Power Line example. to move from 2 to 3 emulator column pages for the Projects Problems section.All sections areex- Fast Precision A new brochure from Pentica panded, with communications An 8 -page application note en-details the advanced capability - as could be expected - Voltmeter titledUnderstandingPower of the MIME -600 8 -bit emulator. showing the greatest growth. Line Disturbances is available Pentica Systems Ltd Stattion Overall, hundreds of new products are featured, each priced A 20 -page booklet from Solar - free from Livingstone Techni- IndustrialEstate Oxford The Ironcontainsawealthof cal Sales Ltd Livingstone Road WOKINGHAM RGII highly competitively. background information on the House 2-6 Queens Road 2YQ. catalogueisavailablefrom measurement technology that TEDDINGTON TW11 OLR. Maplin orfrom W.H.Smith stores at £1.60. Beck capacitors & CAD/CAM 41 la filters 4,111EINO cm a.

so eseniPWINM _ :1011 A 6 -page full colour brochure capability has been produced on the ; A fullcolour brochure pro- Beck range of products by STC viding an introduction to theirElectronic Services The Ca-

range of high-performance pacitor Group Edinburgh drafting plotters for CAD, hard Way HARLOW CM20 2DF. copy graphics, and photoplot- EE 54 December 1987 NEW LITERATURE NEW LITERATURE

Electronic p&p), cash with order from the plines. All of the authors areProduct ranges listed in the Institution of Electrical Engin- British, and many are now onBlue Book include authorized Systems and eers Publications Sales De-the leading edge of researchdistribution lines from major partment P.O. Box 26 anddevelopment in this manufacturers, such as Philips, Techniques HITCHIN SG5 ISA. country -a fact that has con- Marconi, Grundig, Lloyd, tributed heavily to the successThurlby, Thandar, Hameg, and by K.F. Ibrahim ofthesebooks acrossthe Siemens. In addition, a selec- ISBN 0 582 98817 9 world. tion is included that covers the 267 pages - 245 x188 mm Computer- Kogan Page Ltd computer productsavailable Price £7.50 (soft cover) 120 Pentonville Road from Electronic Brokers, and a This is a most welcome bookaided LONDON N1 9JN review of the company's aimed at students taking the second -usertestequipment City & Guilds 224 Course (Elec- Engineering for and computer activities. tronic Servicing) Parts I and II, Manufacture Electronic Brokers and BTEC students at levels I, II, Instruments for 140-146 Camden Street and III taking electronic by D.A. Milner & V.C. Vasiliou LONDON NW1 9PB engineering. It is, however, also ISBN 1 85091 093 6 Industry Blue useful for practising engineers 264 pages - 215x135 mm who would like to back their Price £17.95 (hardback) Book practicalbackground with One of Kogan Page's successful Transistor theoretical knowledge. New Technology Modular256 pages - 150x210 mm The reader is taken from a basic Series, Computer -aided In an attempt to break awaySelector Guide knowledge of Ohm's Law to an Engineering for Manufacture is from the traditional catalogue understanding of electronic cir- intended principally for under- approach used by most elec- by J.C.J. Van de Ven cuitry. It clearly and conciselygraduateandpostgraduate tronics companies, Electronic ISBN 0 85934 179 8 explains the fundamentals ofstudents of production, mech- Brokers has introduced a 256 - 192 pages - 178x128 mm electronic systems, includinganical, and general engineer-page Blue Book including virtu- Price £4.95 (soft cover) radio and television reception,ing, but it is also suitable as aally all the technical information Prepared from a vast database digitalandmicroprocessortechnical reference source forneeded bytheprospective of electronic component systems, amplifiers, oscillators, the practising professional who user of test and measurement specifications, with the aid of digital gates and counters. I paris faced with making financial equipment. the latest computer techniques, ticularly liked the chapter on and engineering decisions con-The new publication, free to this unique guide offers a range fault finding (not found in many cerning computer -aided manu-quaified users, is broken down of selection tables compiled so books), which teststhestu- facturing projects. into 16 sections covering differ- as to be of maximum use to all dent's grasp of the book's con- The emphasis of the book is onent categories of instrumen- electronics engineers, design- tents admirably. computerized systems used intation, each of which is pre- ers, and enthusiasts. The author's stated aim has the discrete manufacturing in-ceded by a general introduc-Section 1 gives a detailed in- been to meet the challenge of dustries and it provides a com-tion to the instruments included troduction,covering compo- conveying complex electronic prehensive study of the techni-in that category and the type ofnent markings, codings, and concepts and systems in a man- cal topics related to computer -measurement they make. standards, as well as explaining ner that may be understood byaided manufacture. Areas con-Categories included, all cover-the symbols used and how the those who have no mathemati-sidered include numerical con-ing product lines supplied by tables are arranged. cal background, but who may trol,robotic technology,flex- Electronic Brokers, are Section 2 tabulates in alpha- none the less wish to acquireiblemanufacturingsystems, oscilloscopes (bothreal-time numeric sequence the com- the necessary skills to servicecomputer -aided productionand digital); analysers; prehensivespecificationsof modern electronic equipment.management. and artificial in-multimeters (digital and over1,400 JEDEC, JIS, PRO - In my opinion, he has suc-telligence. The book provides analogue); signal sources ELECTRON, and brand - ceeded in this very well. an overview of these special-(pulse, function, and RF); TVspecific designated devices. Longman Group UK Ltd ized topics and demonstratesand communications test Section 3 tabulates the devices Longman House how they are all related within aequipment; counter/timers;in a fashion similar to that in Burnt Mill manufacturing organization. power supplies; power meters; Section 2, but here by case HARLOW CM20 2JE Kogan Page's New Technology recorders; and plotters. type. Modular Series, started in 1984, Section 4 considers particular now includes a great number of limits to the electrical booksthatcoverimportant parameters and is sub -divided IEE Wiring topics of interest to production, into six parts, each dealing with mechanical,electrical,and a particular type of transistor. Regulations electronicsengineers,com- Section 5illustrates package The 15th edition of the IEE Wir-puter scientists, systems outlines and leadouts. ing Regulations for Electrical designers,architects, man- Section 6 gives an SMD (surface Installationshave now beenagers, personnel and training mountingdevice)markings reprinted and incorporate all officers,andotherprofes- conversion list. amendments up to and includ-sionals in the industry. All the Bernard Babani (Publishing) ing those of June 1987. books arealsosuitableas Ltd The reprint is identified by itscourse textbooksforunder- The Grampians browncover. Copiesare graduate, HND, and graduate Shepherds Bush Road available, price £20 (UK Incl. students inthe above disci- LONDON W6 7NF 55 EE December 1987 ELEKTOR ELECTRONICS TEST EQUIPMENT

As reported elsewhere in thisA comprehensive instance,aretheanalogue Pulse Generator (*):April issue,this month we start aseries Capacitance Meter, the Audio 1984, p. 26 ff. regular series of reviews of a Sweep Generator, and a host of RLC Meter (*): February 1985, variety of test and measurement Shown to the left in the photo-smallerprojectsfortesting p. 56 ff. equipment. The seriesstarts graph is the LCR Meter on topcomponents, AF, RF and digital Spot Sine -WaveGenerator with a review of a number ofof the Computerscope. Below circuits. (-): May 1987, p. 28 ff., and dual -traceoscilloscopes, and in the centre stack is the Loud- June 1987, p. 38 ft willcontinuewithstorage speakerImpedanceMeter. Overview of publications: Thmperature Probe for DMM oscilloscopes,signalgener- Then come the Microprocessor Audio Sweep Generator (-): (+): December 1986, p. 61 ff. ators,power supplies,mul- Controlled Frequency Meter, November 1985. p. 34 ff. True RMS Meter (+): timeters, frequency counters, the True RMS meter, the Digital AutorangingDigitalMul- December 1986. a 40 ff. pulse generators, LCR meters, Sine -wave Generator. The 2 - tirneter (+): June 1987, p. 51 ff. Variable Dual Power Supply and more. Since it is, however, channel and standard, single - Barometer/Altimeter (+): (+): April 1986, p. 32 ff. appreciated that many readerschannel, version of the VLF November 1986, p. 20 ff. VLF Add-on Unit for inschools and small work-Add-on Unit for Oscilloscopes Capacitance meter (digital) Oscilloscopes (+): February shops, laboratories and elec-seen on top of the stack are (+): February 1984, p. 2-52 ff. 1987, p. 38 ff. The 2 -channel tronic design centres remain in-housed in flat Verobox enclos- Capacitancemeter(ana- extension circuit will be dis- terested in constructing someures. The right-hand stack is logue) (+): May 1987, p. 33 ff. cussedinaforthcoming test equipment themselves ascomposed of the Pulse Gener- Computerscope (+): article. an attractive alternative to theator at the bottom, supporting September 1986, p. 60 ft, and (+) Printedcircuit board(s) more costly commercial equip- the Digital Capacitance Meter, October 1986, p. 41 ff. available. ment, we thought it helpful to the Dual Variable Power Supply, Digital Sine -wave Generator (-) Printed circuit board(s) not remind you all of the number of the Function Generator, and the (+): February 1987, p. 24 ff. available. test equipment projectsthat Spot Sine Wave Generator. Seen Function Generator (*): (*) Printed circuitboard(s) have been published in Elektorin front are, from the left to the December 1984, p. 30 ff. available in limited supply. Electronics over the past few right, the Altimeter/Barometer, Loudspeaker Impedance Please consult the Readers Ser- years. The accompanying the Autoranging Digital Mul- Meter (*): September 1986, p. vices page and the Order Form photograph shows that the ma-timeter, and the Temperature 50 ff. in this issue for details on order- jority of the Elektor Electronics Probe plugged into a DMM. Microprocessor -controlled ing back issues, printed circuit instruments are housed in a No attempt was made to photo- Frequency Meter (+): boards, and copies of the stated standard Verobox enclosure, graphallpublisheditems Decemb6r1984,p.64ff, articles. which makes for a neat andrelated to electronic test and January 1985,p. 46ff, and uniform appearance. measurement-not shown for February 1985, p. 26 ff. EE 56 December 1987 DIGITAL MOTOR DRIVER FOR R/C MODELS

R/C modellers will delight in building and using this ultra -compact, high efficiency, all -digital power driver for electric motors with a current requirement of up to 40 A.

The circuit described here is ciently fast (real time)-hence based on pulse -width modulat- accurate-control of the model ion of power FETs at a fre- is ensured by repeating the quency of 1 to 2 kHz. The motor control pulses at a rate of about driver can be tailored toin- 50 Hz. In a traditional (analogue) dividual needs, which means motor control system as shown that the number of FETs fitted in in Fig. 2, the input pulse is com- parallel in the power output pared with a reference pulse, stage depends on the current whose width corresponds to requirement of the motor used. the neutral position. The width Flyback diodes are included to of the error pulses so obtained ensureasmoothlyrunning is multiplied by a specific fac- motoratallspeeds.Two tor, and the resultant signal is presets not only enable ad- either used for direct control of justing the zero point and the the power stage, or averaged maximum speed in accordance and subsequentlyfedtoa with the R/C system used, but pulse -width modulatorthat in addition select operation of drives the power stage at a rela- the motor in the single or dual tively high frequency. A major quadrant mode. Single quad- drawback of this system is the rant operationisparticularly fact that average output voltage useful for non -reversing motors is not. only a function of the in model aircraft. The proposed pulse -width, but also of the con- controller makes it possible to trol pulse repeat rate. Notably in stop the motor when the control modernmulti -channelradio lever is pulled fully backwards, control systems,thisrateis while the trim adjustment is often dependent on the status pushed ahead. The entire oper- of other channels, i.e., it is vari- ating range of the lever is then able due to circuitry that op- availableforregulatingthe timizes the density of the infor- motor speed (forward), and the mation stream. This arrange- trim is used for accurate control ment readily leads to undesir- of the compensatory reverse able, mutual, cross -effects on force that ensures a smooth overloading and output short- pulse -widthtovoltagecon- channels. The circuit presented touch -down of the model. circuits. verter. The decoder in the R/C here is an all -digital design, and Reversal of the direction of receiver supplies pulses with a is completely free of the above travel of the motor is effected period of the order of 1 to 2 ms. effects. with the aid of an external relay The digital approach Thepulse -widthdetermines for polarity change -over. An all - A speed control for small elec- the position of the relevant ac- electronic reversing circuit ver- tricmotorsisessentiallya tuator in or on the model. Suffi- sion was found too inefficient Block diagram since it required quadrupling The block diagram of Fig. 3 thepowerstage. A motor Digital motor driver for R/C models shows a conventional input sec- reversing relay is, of course, not tion. The input pulse triggers a required for single quadrant Technical specifications: monostable multivibrator applications. (MMV) that supplies the refer- The 5 V supply on the driver Supply voltage: 6-24 V ence pulse. The error pulse is board is used for powering the Output current: max. 40 A fed to a second MMV dimen- HF PW modulation: R/C receiver and, if applicable, 1 -2 kHz sioned for arelatively short any additional servo motors. Efficiency (LJD = 12 V): > 95% Inoperative area around neutral position: 50 ps mono time, which serves to Clearly,theabsenceofa Current consumption of logic circuitry: < 1 rnA createtheinoperativespan separatebatteryforthere- Weight (20 A version): 35 g around theneutralposition. ceiver means a welcome re- On -board driver for motor reversing reversing relay; max. coil The error pulse must be longer duction in space as well as current: 400 mA. than the inoperative span for weight, but due care should be Variation of input pulse -width for the full available speed the motor driver to be activated. taken not to exhaust the motor range is adjustable between 0.5 and 1 ms. MMV2 also resets a 4 -bit binary battery. The motor driver board Zero point adjustable between 0.8 and 2.3 ms. counter, and synchronizes the isprotected against thermal internal oscillator. The counter EE December 1987 is re -enabled when the period for the inoperative span has lapsed. At the end of the error pulse, the current state of the counter is stored in a latch. Evidently, the longer the error pulse, the higher the counter value. The 4 -bit dataword at the latch output thus corresponds to the width of the error pulse at a resolution of 16 steps. A 5th bit indicatesthepolarity, i.e., whether theinputpulseis longer or shorter than the reference pulse. Pulse -width modulation is essentially achieved by comparing the latched 4 -bit dataword with the current counter state. The output of the 4 -bit comparator goes high,and switchesonthe power transistors, when the counter value is lower than the latched dataword. The output periodofthe pulse -width Fig. 1 Prototypes of 3 versions of the driver board: 10 A (left), 20 A (centre) and 40 A (right). modulator corresponds to a full 16 -stepcountercycle.This means that the switching frequency is 2 kHz at an oscillator frequency of 32 kHz. When the oscillator frequency is reduced-for instance. for obtaining single quadrant operation-the switch fre- quencyisautomaticallyre- duced also.

Circuit description The practical realization of the previously discussed functions isapparent from the circuit diagram of Fig. 4. The reference pulse is generated by MMVt, while Pi sets the zero point. XOR gate Ni Fig. 2 Block diagram of a traditional motor driver for R/C models. subtracts the input pulse from the reference pulse, and so sup- pliestheerrorsignal.The 3 negative error pulse triggers MMV2, whichresets 4 -bit protection4- counter 1C3, and defines the start state of the oscillator via Di C inputonN3. The rel. pwIS CL. and an latch counter is enabled when the -11MMVI period of MMV2 has lapsed. The trailing edge of the error pulse loads the current counter 4bit state in 6 -bit latch 1C4, which 11 counter sense can so supply the dataword for MMV2 C noperalive the pulse -widthmodulator. - span rsse Components D3, RI and N2 ef- fectively limit the number of counter steps to 16 by disabling VT'vv the oscillator when CO (CARRY SYNC PWM s;cnas 4 -bit OUT) goes low, and the error comparator pulse is still active. Output CO oscillator goes low when the counter 37C13 - 3 reaches state15 (counting up from 0),freezing the counter Fig. 3 Block diagram of the all -digital motor driver for R/C models. The motor speed is adjustable in 16 stateuntil the error pulse is steps for both directions of travel. finished,and the maximum EE 58 December 1987

4 SV battery, +5V IC Aff u805

CIO SIMIc 1IC 2 0 Ir22 100s $00, a 6V3 o rertr33111111 0 0 s 151414.5 4 nD

/11.-114 = ICI =4030 1414V1.14411/2 = IC 2 =4538 MI a 0 B 7 55 TR a KIWI ittra -CA 8 SC5171 Se 09 - A II 13 Ds 06

c" IC 4 Ds 40174 as12 85170 31422 0000 14505 3o J1 2 85170 TR 3 ,01 961 1414V2 0r5 S 5 RT R -C-S.T1 a M---- 02 " 31F2IC /G00 3 PE4515 1_. 5V , ps 71 iti 91154 to 7 2 t4- P3 CO CZ ; 'I 2 8 IC 5 IMIEI - 4585 ARE s-, 1N4148 Ace. AR9 25 5, 13' fit C. 412 EEO 1_92 031 RI C. *

T4_17 = BuZ t a

battery

Fig. 4 Circuit diagram of the digital motor controller. The heavy linesindicate high current paths.

value is loaded in the latch. of about 1 nF formed by eachvalue just above the supply varying the duty factor over the Bit D6 in the latch is used as the FET, the switch response of the level. full available range of 0 to 16/16, reverse/forward indicator. The power output stage is accept-XOR gateN4functions as an in- the A =B input is made logic corresponding input on IC4able due to the "low" switchverter for latch output bitQ5, low by N4 when the error pulse receives the slightly delayed rate of 1 to 2 kHz. Fast recovery, and controls the A =B input of is longer than the inoperative reference pulse from network high current, flyback diodes Dsthe 4 -bit comparator. When this span. The timing diagram rel- R3 -Cs. When the input pulse is and Daguaranteethatthe input is logic high, the duty fac- evant to the various signals dis- shorterthanthereference motor runs smoothly even attor of the output signal varies cussed is given in Fig. 5. pulse, the latter causes the end low speeds, and at the samefrom 0 to 15/16. When A =B is of the error pulse. Assuming time clamp induced voltagelow, the duty factor varies from Transistors Ti and Ts are in- that link f is fitted, the polarity peaks on the drain rail to a safe 1/16 to 16/16. In order to enable cluded as safety measures. The bit will be loaded as a logic highlevel. When the input pulse is longer than the refer- 5 input ence pulse, the former deter- puLle 3.315 .= OA reveres Ima= 0_9 res tunas mines the end of the error rel.pulse _1 pulse, andDois logic low when M14V2 /010 the new dataword is latched. ISeks The polarity bit is output on Q6 encl. pulse of the latch, and controls relay Ht /r53 T2, driver a darlington transis- inoperabve span/R counter 1414V2106 tor that can switch coil loads up Ii to 400 mA. Jumper e or f is fitted 4 bit dataword new data in accordance with the control 1C4 / 01-134 lever position that causes the I LX reversing relay to be energized. polarity bit 1C4 / 06 In most cases, this will be the aumPid "reverse" position. PWMsignal 105 /013 The 4 -bit comparator,ICs, opt 1 perist reset new drives the power FETs direct ee.etee duty cycle via 100 Q gate resistors for sup- I 1 I I I 0 0202 CA 2.3 pression of spurious oscillation. I (ms) ---4, Notwithstanding the relatively 07cia - high output impedance of ICs, and the high input capacitance Fig. 5 Timing diagram for the main signals in the circuit. EE December 1987 drain-source resistance, Rd -s(on), of each power FET is Parts list used as a current sensing re- Resistors sistor. FET T3isconductive -± 5%1: simultaneously with the power fit;Fia;R4;Rt i =100K R2=22K FETs. The base of Ti is then Rs;R6;R7=47K connected to the drain rail of Rs= 56K the power stage via low-pass Rs = 27K Rs -CE. When the voltage on the fito=10K drain rail is higher than about inc1=10OR 0.6 V, Tiis switched on, and Pi =100K miniature preset for resets thelatch. The power vertical mounting stage is so turned off until the P2=25K miniature preset for next input pulse is received. vertical mounting The latch is automatically reset Capacitors: at power -on since Cs is con- Ci=15n nected to the positive supply C2= 1n0 ceramic rail. C3= 10n ceramic C -s= 680p ceramic The protective circuitry set up Cs =100p ceramic around Ti and T3 is effective in Ce=0p22; 6.3 V; bead tanta- 3 ways: lum C7=47p; 6.3 V; bead tantalum (short- II Toohighcurrents CB=22p; 25 V; bead tantalum circuits) cause a voltage drop Cs;Cio=100n (miniature) across Rd-Aon) that results in de- Ci =47p (see text) activation of the power stage. II When the supply voltage, Semiconductors: and hence the gate drive for Di ...Da incl.=1N4148 the power FETs, is too low, the Ds (De.)=BYV79-50 Ti =8C547 output stage tends to operate in T2=BC517 the linear range, causing con- T3=BS170' siderable dissipation. The pro- T4;Ts (Te;T2.)=BUZ11' tective circuitry prevents this IC1=4030 happening, and at the same IC2 =4538 time safeguards the motor bat- IC3 A4516 tery against excessive load cur- IC4=.40174 rents. !Cs= 4585 ICs= L4805 I Rd- s (on) of the FETs riseswith temperature, so that the protective circuitry is active For motor currents higher than at lowercurrents, i.e., it 20 A. becomes more sensitive. + Available from Cricklewood Electronics Limited.

Construction and use Miscellaneous: in practice SPDT or DPDT relay suitable for Given the number of compo- available battery voltage. Contact current rating as required for the nents onit,the ready-made relevant motor. printed circuit board for the 4off car -type male terminals with digital motor controller is of mating sockets. modest size. The PCB shown in 4 off 20 -way turned pin terminal Fig. 6 is a double -sided, but not strips for making the IC sockets. through -plated, type. The large Angled 3 -way header with mating copper areasat both sides jumper. enable fitting car -type male ter- PCB Type 87098 (available through Fig. 6 Track layouts of the double -sided board, and the component the Readers Services). minals which are capable of mounting plan. carrying relatively high currents. For applications wheregoes for a number of IC socket cessible with the tipof thestage isto requirement. The space is tight, and the motorpins.The socketsarecon- soldering iron. minimum number is I, the maxi- current is fairly low (< 5 A), theveniently made from terminal mum 4. As a general rule, each large copper area can be cut strips to enable careful It was found that the on -board power FET can carry about off, and soldering pins can besoldering to the tracks at the oscillator may require fitting an 10 A, but it should be borne in fittedinsteadofthehigh - componentsidealso.Itis additional 47 pF capacitor, C11, mind that the overall efficiency current terminals. strongly recommended to toensureacorrectoutputof the power driver increases The completion of the board isfollow the constructional stepssignal and reliable operation. with the number of FETs fitted. illustrated in Figs. 7a... Te. Allas suggestedinthephoto- This capacitor is shown with an A second flyback diode, De, is resistors are fitted upright, and graphs of Fig. 7. Push -fit and asterisk in the circuit diagram, required when more than 2 some component leadsare solder the terminal strips one at and additionally in the white FETs are used. For the 20 A ver- soldered at the track side and a time, making sure that all pins circle in Fig. 7f. sion of the circuit,itis rec- the component side to effectthat require soldering at the As already noted, the number ommended to mount 2 FETs through -contacting.Thisalso component side are well ac- of FETs in the power output and 1 flyback diode. EE 60 December 1987

a® 2

Fig. 7a Step 1: all components are to hand for assembly. Note that Fig. 7d Step 4: Mount the parts at the PCB edges, and the vertical the PCB in the photograph is a prototype without the component presets. Fit the ICs in their respective sockets. overlay provided on ready-made hoards supplied through the Readers Services.

Fig. 7b Step 2: a number of components require soldering at both Fig. 7e Step 5: the power FETs, flyback diodes and the voltage sides of the PCB. regulator are fitted in a row and secured with insulating PTFE washers and a long M3 bolt plus nut.

Fig. 7c Step 3: the IC sockets are fitted as terminal strips to enable Fig. 7f The area in the white rectangle may be tinned when the through -contacting via some of the pins. output current is higher than 15 A or so. Shown encircled is the 47 pF capacitor that may be needed to ensure correct operation of the 32 kHz oscillator. 1

EE December 1987 When the battery used supplies however, that a motor requiring more than 7 V, the gate drive of a relatively high starting current the power FETs can be slightly may cause the battery voltage improved by cutting the track todropbrieflybutcon- that forms connection X (see siderably. In critical cases it is, the circuit diagram) and fitting a therefore, safer to power the re- diode Type 1N4148 with the ceiver from a separate battery. cathode connected to ground. Voltage regulator ICe should Thismodificationraisesthe be fitted with a heat -sink of am- supply voltage-and hence the ple dimensions when itis to logichighlevel-byabout power a relatively heavy 5 V 0.6 V,and allowsaslightly load (servos, receiver, lighting), higher maximum output cur- at a high input voltage (> 10 V) rent per FET. from the motor battery. The power FETs,flyback diodes The connections of the board to and the voltage regulator are the motor, the battery and the TO220 style components, and reversing relay are shown in the can be secured as shown in Fig. wiring diagrams of Fig. aa (dual 7e with the aid of a long M3 bolt quadrantoperation) and 8bwhich isrun through PTFE (singlequadrantoperation). washers and spacers. The metal The latter circuit enables im- tabs of the TO220 components plementing an electric brake as should remain insulated, how- discussed earlier. The series ever,andit isnotrec- resistor in Fig. 8a has a value ofommended to use a common 0.2 to 0.5 Q. It prevents current heat -sink. The FETs and the surges, excessive loading of the diodes do not run hot under battery, and erroneous action normal conditions. on part of the protective circuitry, when the motor's direc- Ascertain that the motor is fitted Fig. 8 The motor controller can be wired for dual quadrant (8a) tion of travel is reversed at full with a proper noise suppres- and single quadrant operation (8b). speed. The resistor does not sion network before connect- carry current when the motoring the driver board. A single runs in forward direction. The capacitor is usually not enough, function of the fuse in Figs. 8aand a suggestion for a more ef- and 8b is self-evident, as is the fective network is,therefore, fact that the coil voltage of the given in Fig. 9. The chokes are DPDT or SPDT relay matchesa few turns of enamelled cop- the battery voltage. per wire on or through small The regulated 5 V supply rail on ferritecores. The 10 nF the motor controller board may capacitors are preferably feed - be used for powering the re-through types for optimum sup- ceiverand,ifneeded,the pression of motor noise at the servos and thelighting, butoperating frequency of the re- only if their total current drain is ceiver. The network isfitted Fig. 9 Suggestion for an effective noise suppression network. less than 400 mA. Remember direct onto the motor terminals andsubsequentlyscreened Table 1 using a grounded metal Trouble shooting guide enclosure. Presets Pi andP2are used for adjusting the zero point and the Problem Possible cause Possible remedy maximum motor speed,respectively. A jumper fitted in Fit Cu (see Fig. 7f). Overshoot of maximumOscillator malfunction. position motor speed. Wiper Pi turned to Adjust P2. e orf causes the junction Rio-Di. reversing relay to be energized only when the motor runs in re- Reversing relay Protective circuitry Fit current limiting verse. clatters after fast activated by peak resistor (Fig. 8a). reversal of direction. reversal current. Increase gate drive voltage (see note below). (see text). Decrease value Finally, a number of prototypes of R5, or increase Rs. of the digital motor controller were built and tested to enable Slow motor response Battery voltage drops Charge motor battery spotting, analyzing and rem- on acceleration due to starting current. or use a more powerful commands. type. edying the most frequently encountered malfunctions.The Mutual influencing Noise suppression Fit noise suppression results are summarized in Table or servos and ineffective. Battery network (Fig. 9). 1,to form a guide for trouble motor. voltage too low. Recharge battery. Power receiver from separate shooting, should this be re- battery. quired to get the unit to function satisfactorily. TW Note:for very fast reversing action, the protection can be incapacitated by omitting either Ti or R9. EE 62 December 1987 INFORMATION THEORY AND ENCRYPTION

by B.P. McArdle

Anyone who is, or becomes, involved in encryption operations and cryptosystems must wonder about their connection with Information Theory. In this article, Brian McArdle briefly explains the areas of overlap and difference.

Consider a channel where a ation is determined by the diffi- message xi drawn from a set culty in deducing the key from Ixi,x2,x2, ...,xn)of n possible the ciphertext. Modern cryp- messages, as illustrated in fig- tosystems also require that the ure1,is transmitted between key should not be deduced sender A and receiver B. The froma matchedplaintext- message could be just a letter ciphertext pair(s). However, this from an alphabet of n letters or point is not developed further a symbol. However, it is infor- because we are not actually mation of some type and is ex- ceiver B does not receive false Theory but are not used in this analysingparticularsystems. changed between A and B. The information. If the channel is article. The relationship between En- electronic representation of xi very noisy such that the signals cryption and Information could be a particular waveformarecorrupted duringtrans- Theory is now considered by or a set of binary digits (bits)mission this adds to the prob- Encryption operation outlining the results of a famous paper. etc. For example, the Englishlems of the receiver. However If xi is encrypted as illustrated alphabet of 26 letters requires a the techniques used to reduce in figure 2 set of 5 bits to represent a letter the effects of noise are not be- Shannon's theory ing examined in thisarticle. and since 25=32 there are 6 Ex(xi) = yi (3) redundant combinations.For And the technical limitations of Shannon (Ref.1) in his paper thepresentthemethod ofthe channel, such as in the compared the effects of the electronic representation of secrecy operations to the prob- signallingisnot being con- Hartley -Shannon Law are not yi instead of xi is transmitted. It lem of noise. The letters of the sidered.If each xi has pro-considered. is easier to keep track of the ex- babilityPr(x)=piofbeing ciphertext should appear ran- planation by taking the xi 's and dom with no preference for any chosen for transmission by A yi 's to be letters but this is not the information entropy of the A priori and a particular letter(s) but only the essential. The encryption oper- correct key will produce a channel is givenbythe posteriori information ation is varied by changing the equation meaningful message after The receiver may have some parameter K called the key. This decryption. He assumes that a advance information before the is the secret information and H = _r pilog2(p) (1) cryptanalystknowsorcan message is sent. This is known shouldbe knownonlyto deduce the method of encryp- as a priori information and the a andreceiver.The minussign sender tion (which we will not examine The makes H cleartext)and positive because every pi s 1.priori probability is the prob- plaintext(or here) and has unlimited ciphertext are xi and yi respect- The base of the logarithm does ability that it is correct. The a ciphertextbut noplaintext- posteriori information and the ively. An unauthorized listener not have to be 2 but this means ciphertext pairs. He explains associated a posteriori prob- (cryptanalyst) on the channel that the dimension of H is bits. If the requirements of a crypto- ability refer to the transmitted wouldprobablyknowthe aparticular message xi has systemusingthefollowing message afteritis received. method of encryption but not parameters: pi =1 which means that pi = 0 for use. The it.j, then H=O. If all messagesThesearecommonly usedthe actual key in (a) entropy of the plaintext H(X) are equally likely to be trans- parameters in Information strength of the encryption oper- computed as per equation (1); mitted (uniform distribution) (b) entropy of the ciphertext 2 H(Y) computed as per equation H = log2(n) (2) (1); (c) key entropy H(K) computed

which is the maximum value Encryption Decryption as per equation (I); Channel Sender A Operation Operation Receiver B (d) key equivocation computed and is also the number of bits Message Mossn. required to represent a EK(N) = Yi two = according to the equation message. The larger the value of H the greater the uncertainty H(K/Y) = in the information transmitted Key K Key K 872s4 - 2 - Pr(KY)LOG2Pr(K/Y) (4) over the channel. If H=0 there is no uncertainty and the re- with joint and conditional prob- EE December 1987 abilities being used. We need whose dimension is symbols or H(K) = log2(256) = 56 (9) RSA Public Key Cryptosystem not be concerned withthe letters. This is the number of let- (Ref.4) have become subjects in various steps in the analysis but ters of the ciphertext required U = 18(approx.). (10) their own right. Any student he deduces the following result to determine uniquely the key who wishestostudy Cryp- (remember that Shannon as- From Shannon's Theory,this tology would be well advised to H(K/Y) = H(K) - H(Y) + H(X) = sumes that a cryptanalyst knows means that 18 blocks are re- startwithbasicInformation H(K) - nD (5) the method of encryption and quiredtoestablishthata Theory and Shannon's paper. has unlimited ciphertext but no decrypted message is mean- where D is defined as the Re- plaintext). ingful text. If 8 bit ASCII is used, dundancy The dimension is then 18 blocks = 144 symbols. bits per symbol which is usually Example 1 However,sincetheASCII Appendix aletter.This parameter re- Consider a simple substitution alphabet has 128 symbols, the Equation (4) can also be written quires further explanation as follows: result is not too different from in the form becauseitiscentral to thePlaintext:ABCDEFGHIJK example 1. In reality, a crypt - theory and conclusions. LMNOPQRSTUVWXYZ analyst could not try each key of H(K/Y) = Most languages have a Ciphertext: GZWJPABIMT M 256 possiblekeysbutthe -E EPr(ki,y).log2PrOci/y0 (11) peculiarity that certain lettersDNECSOYXVHLFKQRU. example doesillustratethe j=1 i=1 occur more often than other let-The number of possible tables principle quite satisfactorily. ters. Consider a message which which is the equivalent of the The other parts of Shannon's where m is the number of poss- is encrypted by replacing each various keys is 26! such that paper need not be consideredible keys. The other form is letter with another letter ac- in presenting a short overview. commonly used in text books. cording to some rule. A good H(K) = LOG2(26!) (7) However, his results are de- cryptosystem will result in a ducedusing manyofthe ciphertext which has a uniform U = 28(approx.) (8) parameters and formulae which distribution of letters such that are now part of Information no letter or group of letters oc-which agrees very well with Theory. curs too often. This means that practical results. Any reader H(Y) and H(X) have differentwho wishes to know the actual References values. Although they are both techniquestodeducethe (1) Shannon, Claude E.; Com- measures of uncertainty, the dif- tables should refer to (Ref.2). Conclusions munications Theory of ference between themisa Encryptionisnotreallya Secrecy Systems. Bell measure of redundancy. Ob-Example 2 branch of Information Theory. SystemTechnical Journal, viously, H(Y) will be larger than Consider the Data EncryptionThere are important areas of volume 28 (1949). H(X) from equation(2).For Standard (Ref.3) which turns a overlap but the theories and (2) Friedman, William F.; English D=3.2.If H(Y)=H(X), 64 bit plaintext block into a 64 techniques for the evaluation of Elements of Cryptanalysis. then D = 0 and H(K /Y)= H(K) and bit ciphertext block using a 56modern cryptosystems, such as Aegean Park Press: U.S.A. evenunlimitedamountsof bit key block (Fig. 3). the Data Encryption Standard or (1976). ciphertext encrypted with the (3) Data Encryption Standard. same key do not reveal the key. 3 FIPS PUB 46 National Bureau Thus one of the most important Bit Bit I ofStandards,Washington conclusions of the paper is that PtirAell Data Encryptim Ciphertext DC. U.S.A. (1977). cryptanalysis is only possible Block Standard Btxt. (4) Rives', R.L. and Shamir, A. because of language redun- Bit 64 and Adleman, J.; A Method /P.a` " dancy. for obtaining Digital The 2nd important parameter is Signatures and Public Key Key the Unicity Distance given by Stock Cryptosystems.Communi- 87244 - 3 8456 cations of the ACM, volume U = H(K)/D (6) 26, number 1 (1983).

CORRECTIONS

Long-range infra -red Horn loading revisited SSB receiver for 20 transmitter -receiver September 1987, p. 44 if. and 80 m November 1987, p. 43 Unfortunately, there are a few errors in November 1987, p. 53 On thecircuitboard, R38iser- the text, which should be amended as The value of R13 in the circuit diagram roneouslyconnectedtojunction follows: is erroneously given as 510 Q. The Pe-R4o, while it should go to junction Page 44, column 4, line22: .. .For correct value is 560 Q. however, as 1140-Ecrth, as shown in the circuit k2= ...should read. . .For kr= . stated in the parts list. diagram, Fig. 10. Page 45, column1, line 32:. ..fp which ...shouldread. .fc which

Page 48, column 2, line 25:.. .domestic 12 W system .. .should read. . .domestic120 W system . EE 64 December 1987

APPLICATION NOTES The contents of this column axe based on information obtained from manufacturers in the electronics industry, or their representatives, and do not imply practical experience by Elektor Electronics or its consultants. 3 -PHASE POWER CONVERTER FOR INDUCTION MOTORS by K. Wetzel & W. Schumbrutzki' A newly developed integrated pulse -width modulator and fast switching power FETs are the key components in a converter design which allows the good control characteristics of DC motors to be achieved with the more versatile 3 -phase motor.

The most widely used three-Advantages of starting, the slip frequency is These advantages apply to both phase motoristhesquirrel converter -fed three- low and thus the multiple start- synchronousandinduction cage type. Its features are well phase motors ing current can be reduced to motors. The converter -fed known. Having no commutator the rated value. Furthermore, it three-phase motor is ideal for or brushes, it gives a long ser-Converters are designedto is possible to produce a de- drives which require vice life and runs very quietly.generateathree-phase AC fined excess starting torque or long operating times, As there is no brush arcing. RFI voltage from a DC source. If the to generate a torque at stand- high speed, suppressionisnot required. three-phase voltage is variable still, e.g. to keep a robot's arm variable rpm, Becauseofthethree-phase in frequency and amplitudesuspended in a fixed position. frequent reversing cycles, rotating field the motor has high andsuppliesathree-phase Reversing the direction of ro- low -noise, maintenance -free starting and pull-out torque, is motortheabove -mentioned tationislikewisefacilitated. operation. overload -proof and takes veryoperating characteristics of the Thisisusually achieved by Typicalapplicationsofvari- littlespace.Therotational motor will be extended con-reversing the connections ofable -frequency AC inverters speed is determined solely by siderably. Speed is controllable two motor windings. In con- are: pumps, fans, machine tools, the operating frequency and over a wide range correspond- verter operation only the con-robots, spinning machines, ve- the number of pole pairs in a ing to the frequency variations. trol pulses are interchanged by hicles and washing machines. given type. In rated operation, A drive capable of handling 0 to softwareinstructions.Almost slip speed is negligible in view 600 Hz has been built and is de- unlimited control applications The three-phase of the operating frequency. Ascribed here. Used with a two - are possible if the control logic voltage supplied from three-phase power source ispolemotorthisfrequency of the converter is made part of necessary to operate the motor.would allow 36,000 rpm. The thewholeelectronicdrive the converter to the Line frequencies being low,motor iscontrollable byits system and programmed se- motor is not like 50 Hz, allow only low motor freelyselectableratedfre- quences or measured valuessinusoidal speeds. quency, in other words, upon are used to control the motor. Figure 1 shows the principle of the converter design, which is based on the Type SLE4520 3 - phase generator. Line AC voltage is rectified by a bridge rectifier and smoothed by a reser- voir capacitor. The smoothed DC voltageis called the in- termediate circuit voltage. The threeterminalsofthe three-phase motor are connected to the outputs of the power inverter (in Fig. 1six SIPMOS transistors). The desired motor

Messrs Wetzel and Schum- brutzli are with Siemens AG, Components Division, Applied Electronics, in Munich, Federal Fig. 1 Main components of a power converter for 3 -phase motors. Germany. 65 EE December 1987 frequency is generated in the quency would certainly restrict controlblockconsistingof the pulse -time variations for an microcontroller and PWM. optimum sinusoidal shape. Usually, frequency and associated voltage-and thus motor pulse nurnters speed-may be selected over a 4. Pulse -width wide range by means of an ad- MP- modulation juster.A sinusoidalvoltage The principle of pulse -width would increase the power dissi- modulation is shown in Fig. 3. A pation in the converter to an ex- microcontroller with timer and cessive level. The overall ef- down counter is needed to ficiency would be unaccept- modulate pulse widths. able. Therefore the undershoot Another minimum requirement method is applied here. The is a register to pre -load the in- pulsed voltage applied to each itial count value and a motor winding switches it off at L predivider to adjust the counter short intervals. On and off times frequencyinsteps.As a of the pulse sequence are con- -u register and a counter are re- trolled in a way that the average 4 quired in each phase, they are valueofallon -cycles zero level rep- 4 integrated in the new SLE4520 resentsasine -waveshape pulsewidth for: instantaneous amplitude pulse -width modulator together (Fig. 3). This process is called +0 with some additional functions. pulsewidth modulation. Since Functional description: the in- the motor inductance acts as an period of PV/M signal itial count value is loaded via energy store, current depends 4 the register from the microcon- on thepulse widthofthe troller to the down counter. The voltage pulses. Figures 2 and 3 87261-2 down counter runs down to illustrate the process. Figure 2 zero using the predivided CLIC shows the current flow in a load frequency (count clock). In this with a pulse -width modulated Fig. 2 Principle of pulse -width modulating a sine -wave voltage. cycleanegativesignalis supply voltage. It can be seen available at the output (Fig. 4). A that the current approaches the time signal is generated simul- ideal sine waveform with in- taneously in the timer of the creasing number of pulses (syn- microcontroller. After this inter- thesis points) used to build up a val has lapsed, a transfer pulse sine wave. But the pulse -width (synchronization pulse) is also determines the current am- passed to the down counter to plitude. Decreasing all pulse - start another count down from widths in the positive sinusoidal theinitialvaluefromthe region reduces the amplitude register. If,meanwhile,the of the synthesized sine -wave microcontroller has written a voltage by the same factor. With 0' 160* 360° new value into the register, the the same load applied less a) 12 pulses per period pulse width generated at the sinusoidal current flows (Fig. 2). outout is modified. To obtain a A 1:1 duty cycle of the clock fre- r proper pulse -width modulation quency for all pulses results in the down count period has to zero current. be equaltoor below the The minimum clock frequency transferpulse sequencein- depends on the motor induct- itiated by the timer. ance. The clock frequency re- The timer determines the clock quired rises with reduction of or switching frequency and the inductance. Consequently down counter cycle decides small motors and high rotational 0' 180° 360° the pulse width. Pulse -width speeds permit high clock fre- b) 36 pulses per period modulation for a sine wave is quencies while large motors shown in Fig. 2. The sine wave and low rotational speeds mean is divided into a number of syn- low clockfrequencies. The thesis points. To each point an selected clock frequency may, amplitude is allocated which however, exceed the required correspondstoaparticular minimum. One synthesis point pulse width. With a pulse width ofasine -waveconsistsof I 11 of 50% the average voltage is several uniform pulses. Often zero (see Fig. 3), with 100%, the the clock frequency is chosen maximum positive voltage and much higher than necessary to with 0%, the maximum negative avoid excessive noise (beyond 0° 180° 360° voltage is obtained. The the limit of audibility). The emit- c) 36 pulses per period switching frequency 87261-3 (e.g. ted noise primarily depends on amplitude -factor = 0.33 15 kHz) is usually kept constant the current characteristic. The Fig. 3 Illustrating the principle of synthesizing a voltage waveform to generate a particular sine - closeracurrentcurveap- with the aid of pulse -width modulation. The sine -wave shape of the wave frequency whereas the proaches the ideal sine wave- current waveform is improved by the number of synthesis points pulse width is varied from one form, the less noise is gener- (3a; 3b). Current approximation is also possible when the amplitude synthesispointtoanother. ated. Too high a clock fie- factor is lower than 1 (3c). Values are compiled in a table EE 66 December 1987 within the microcontroller. A circuit. This is particularly im- continually changing fre- r nTicro-:canTrollTr f-pu-lsevriTithmodulator portant for bipolar switching quencyisobtained by ap- transistors but also if the power propriately reducing or exten- pulsewidth - transistors have to be driven via ding the switching frequency register a voltage isolating optocoupler period, or, in other words, the susceptible to delays. 'clock load timer interval. IntheSLE4520pulse -width As already mentioned, the sine - modulator up to 16 dead time wave current to be generated is programmable down -counter intervals can be generated from approximated by a number of divider 0 to 15 x 4 (or 6)/fctx in steps synthesispoints. Each point of 4 (or 6)/f cis. At zero dead corresponds toatleast one dock - zero output time both output pulses of one cycleoftheswitchingfre- 'Igenerator ----tdetector phase are in inverse to each quency. The number of syn- other without any delay. Data thesis points for each full sine - are transferred to the pulse - wave cycle must be a multiple width modulator by writing into of six as otherwise a 120' phase Fig. 4 General organization of a pulse -width modulator with "intelligent" control. phase registers I, 2 and 3 via the displacement cannot be 8 -bit data bus PO and the ad- achieved for three-phase oper- dress decoder latch. At one ation. increasing the number of syn- also clock the microcontroller. thesis points or pulses per point The operating frequency (oroutput the 3 -bit address is de- For the sinusodial frequency coded and latched at the falling the following formula applies: with a given switchingfre- count frequency) is generated quency. via a programmable divider. edge of the ALE clock until the data are available at the bus r 12_ The available divisors 4, 6, 8, 12, SN 16, 24, 32 or 48 and the deadtogether with the WR signal. The SLE4520 time delay are archieved by Thetransferpulseforthe where The SLE4520 pulse -width loading a number into the div- Jr = synthesized sine -wave fre- registerisproduced by an modulator is a control deviceider control register and into AND -logic operation from the quency (motor fre- which reads the data provided the appropriate dead -time WR-signalandtheaddress quency), by the microcontroller and con- register. Dead time is a delay fs = switching frequency, stored. The pulse -width vertsthemintopulse -widthrequired in case the halfbridge modulated signal is generated S = number of synthesis modulated clock pulsesfor transistorsexhibitexcessive points, by azero decoder and a three phases driving the power switchingdelays.Herethe presetable 8 -bit down counter N = number of equal pulses half -bridgesvia intermediary delay has to be compensated per synthesis point. which can be stopped via an stages. The SLE4520 is compat- by decreasing the number ofenable input. The transfer pulse ible with all kinds of microcon- control pulses. The SLE4520 has The switching frequency is de- (one instruction cycle) of the trollers and suitableforall two outputs for each phase toprocessordeterminingthe termined by the timer interval types of three-phase motorscontrol individually the upper inthemicrocontroller.The switching frequency loads the because of its large variety ofand lower transistorsinthe timer frequency of the micro - registercontents into the selectable clock frequencieshalfbridge. Output pulses may presetable counter and a "1" controller used here is1 MHz. and pulse widths. Fig. 5 shows be delayed by a programmable appears at the 8 -bit OR gate out- A maximum of 256 ps time inter- the block diagram of the SLE dead timeto prevent simul- val results for the 8 -bit timer put. This 1 digit enables the 4520 PWM. The IC is operated taneous switching of the half - counter and causes it running correspondingtoa3.9 -kHz at the crystal frequency of anbridge transistors, thus down. Upon reaching zero the switching frequency. For on -chip oscillator which may eliminating the risk of a short- higher switching frequencies pulse ends and the counter is the timer is counted to below 8 bits with time steps of 1psbe- ing achieved. For a desired frequency of 20 kHz, for example, switch titre 50 steps = 50pShave to be pro- ALE tit latch 8 tit latch 8 tat -latch latch Prase I 0,1,e 2 Masi 3 grammed. The maximum syn- 4 nits address thesized sine -wave frequency is Latch/ obtained at a high switching fre- decoder quencywithsixsynthesis WR points per period (roughly) and one pulse per point: SYNC boat 15.625 kHz down -counter dawn -counter dayinsusuntet Lilt - 2604 Hz L1/2 6 x 1 XTAL I 4 -blt- LI L2,1 ffrrider L2 8 There are hardly any objections latch L2/2 to generating extremely low L3/1 1312 sine -wave frequencies as the program - XTAL 2 number of synthesis points and usable zero detector zero detector pulses per point may be almost dander unlimited, e.g. L

clear status 3906.25 Hz- 0.16 Hz f -240 x 100 set status If a generated sine -wave fre- stance quency is to be varied, minor a major frequency changes may be performed by reducing or Fig. 5 Internal organization of the Type SLE4520 PWM controller for 3 -phase systems. EE December 1987

Table 1 stopped until the next transferIn the pulse -width modulator are given in Table 3. pulse arrives. the dead time is obtained by Without dead time PH 1/2 is in- The SLE4520 has a locking cir- linking the pulse -width verted to PH 1/1, PH 2/2 to PH Valuedivider ratiodivider ratio cuit to inhibit all outputs via one modulated source signal and its 2/1 and PH 3/2 to PH 3/1. The counter delay clock inhibit line. This feature is very delayed signal. The delay is ob- active switching stateis low: 0 1:4 1:4 useful,e.g. ifuncontrolled tained by passing the source With a programmed dead time 1 1:6 1:6 pulses must be withheld fromsignal through a 15 -bitshift the negative edges of the out- 2 1:8 1:4 the power stages over the en-register with 15 outputs. The put signal are shifted to the 3 1:12 1:6 tire settling time of the micro -shift pulse is either fquanz/6 or right by the dead time. The out- 4 1:16 1:4 controller. Furthermore, all out- /cilium/ 4,depending on theputs are capable of directly 5 1:24 1:6 put stages and thus the motor contents of the divider control driving TTL devices or opto- 6 1:32 1:4 can be switched off immedi-register. couplers for voltage isolation of 7 1:48 1:6 atelyin criticaloperating To select the delay and the drive blocks and power circuits dead time, only one output of Table 1 Allocation of value in phases caused by overload, with currents up to 20 mA. the divider register to the div- over -temperature and externalthe shift register has to be ad- The SLE4520 is a CMOS device. ider ratio by which the hazardous situations. Via a cut- dressed and then switchedand non -used inputs should, SLE4520 operating frequency is off flip-flop this locking state is through to the logic circuit. This therefore,beconnectedto selected. either maintained or cleared. isprovidedbythree 1:16 ground or the positive supply The control output is likewise multiplexers. 15 dead times are rail. Finally, Table 4 shows the Table 2 suitable for indication or feed-presettable(incl.zero deadrelation between counter fre- back to the processor. time)bywritingavalue - quency andswitchingfre- To produce low switching fre-between 0 and OFti into the ap- quency for a SAB8051 micro - Word in Divider Divider quencies with a simultaneouslypropriate control register. controller operating at 12 MHz. dead timeratio 1:4ratio 1:6 Dead time depends on the TW memory dead timedead time high microcontroller operating quartzfrequencyandthe (psi (ps) frequency the divider control register is loaded in the initialpreset divider ratio (1:4 or 1:6). Source: 0 0 0 routinewith an appropriate For a 12 -MHz quartz frequency Siemens Components XXI 1 0.33 0.5 number. Allocation of value and the programmable dead times (1986) Nos. 1 and 2. 2 0.66 1 3 1.0 1.5 dividerratioisshownin 4 1.33 2 Table 1. Table4 5 1.66 2.5 The switchingcycle(deter- 6 2.0 3 mined by the initial value in the 7 2.33 3.5 auto -reload register of the pC) Divider Counter Operating Switching Resolution 8 2.66 4 should be selected after the ratio frequency time Timer 0frequency 9 3.0 4.5 ratio is fixed so as to barely 1:6 2 MHz 64 ps 15 6kHz 7 bit 10 3.33 5 reachthemaximumpulse 1:6 2 MHz 128 us , 7.8kHz 8 bit 11 3.66 5.5 1:12 1 MHz 128 us '7.8kHz 7 bit 12 4.0 6 width. This means that with a 1:12 1 MHz 256 ps 3.9kHz 8 bit 13 4.33 6.5 PWM counter operating clock 1:24 500 kHz 256 us 3.9kHz 7 bit 14 of,say,1 MHz (oscillator fre- 4.66 7 1:24 500 kHz 2 x 256 ps 1.95 kHz 8 bit 15 5.0 quency of 12 MHz, divider ratio 7.5 1:48 250 kHz 2 x 256 us 1.95 kHz 7 bit 1:12) and a table value of 127 (7 1:48 250 kHz 4 x 256 ps 975 Hz 8 bit Table 2 Dead time presettable in bits) the counter reaches zero the relevant register using div- after 128 ps. ider ratios of 1:4 and 1:6. Table 4 Allocation of the counter frequency and the switching Table 2givesa number offrequency of the SAB8051 microcontroller. Table 3 useful allocations of counter and switching frequencies for PinDescription the SAB 8051 (12 MHz clock). 1 VDD 5-V connection 3 -bit Pulse generation in the three 2XTAL1 quartz connection address latch processing channels is done by 3XTAL2 quartz connection 00 8 -bit latch for PH1 a presettable 8 -bit downcounter 4P7 01 8 -bit latch for PH2 and a zero detector (OR gate) 5P6 02 8 -bit latch for PH3 which is connected to the eight 6P5 03 dead time latch counteroutputs.Withthe 7P4 input pins to be 04 divider latch transfer pulse from the 8P3 connected to data bus 9 P2 Table 3 Addressable latches in microcontroller (width is one 10 P1 the SLE4520. instruction cycle) the repetition 11 PO rate of which determines the 12 PH 3/2 output phase 3 inverted Li switching frequency, the ,,,,,,. C I If ELK WI 13 PH 3/1 output phase 3 normal (active low) ZIA: IIC I Tr smc presettable counter is loaded 14 PH 2/2 output phase 2 inverted ;UL: IC I23 rSf with the contents of the appro- 15 Vss ground connection PI 4.0 18 Qt priate register and a 1 appears 16 PH 2/1 output phase 2 normal (active low) Pi 5C 1 v. ,. at the zero detector's output 17 PH 1/2 output phase 1 inverted GS EC 123 ;is (provided the register does not 18 PH 1/1 output phase 1 normal (active low) z'. 7 C 1 22 SU -suns 19 INHIBIT inhibit (active low) sets all phase outputs to H contain OOH). This 1 digit P3 20 STATUS status of status flipflop 3C 137 EMU -STATUS enables the counter and starts it Pt -IC 12: SUNS 21CLEAR STATUSresets status flipflop ,1 ,c III rIPIMPI running down. When zero is 22 SET STATUS sets status flipflop 22 !IC I tf :14711 reached the pulse ends and the 23 RES chip reset :hl., Iti I r, 22133 counter is stopped until the 24 WR input for WR pulse from microcontroller .nls, Tit I ts P1.12/1 next transfer pulse arrives. The 25 ALE input for ALE clock from microcontroller %,Iit .. C I n ,,-. quartz frequency multiplied by 26 CSE chip select the divider ratio clocks the 27 SYNC input for carry pulse from microcontroller 28 CLK OUT output quartz frequency for microcontroller Fig. 6 Pinning of the SLE4520. PWM counter. EE December 1987

PRODUCTS NEW PRODUCTS NE1A Dual -channel design and development for manufacturers. Itis useful for 40/20 MHz measuring and verifying signal frequencies,for pulse coun- oscilloscopes ting, and as a tachometer or a timer. STC Instrument Services has The cost of the instrument is extended its growing range of £299, including all the connect- Hitachi oscilloscopes with the ing cables, a handbook and a introduction of the new high- one year guarantee. performance V-212 DC to Flight Electronics Limited 20 MHzand V-42240 MHz Flight House single time -base instruments. Ascupart Street Both feature dual -channel oper- Southampton SOl 1LU. ation and a high sensitivity of Telephone: (0703) 227721 1 mV/div. Telex: 477389 FLIGHT G Housed in a compact Fax: (0703) 330039 (3678:11:F) 310 x130 x 370 mm package, tonicallyregulated,contain these versatile instruments offer their own 220 V/24 V power New intelligent a wide range of features includ- suppliesandfeaturecon- frequency ing a 6 in. CRT with internal tinuous temperature adjustment Protective Trans- graticule; an autofocus circuit between 150 °C and 400 °C. counter port Cases For and scale illumination (422); a A built-in vacuum pump makes DC offset function (422); voltage thedesolderingstationin- The FC-8100G isanew, Economical and frequency reading outputs dependent of any external air microprocessor -controlled, (422); alternate magnify function pressure connection. The high resolution, frequencyScope Family (422); VERT mode triggering pump is foot -switch activated, counter. Made in Taiwan by (422); an accuracy of +38/0; a creates a vacuum of GW Instrumentation, the ECW (Electronicand Com- stable, low -drift design; 8 divi- 7NI/Min.Max, and is fitted with counterisavailableinthis puterWorkshop Ltd.) an- sionsofdisplayeddynamic in -line foam filters to prevent country only from Flight Elec-nounces a range of carrying range and accurate, distortion - contamination. tonics. casesfortheeconomically free measurements; TV sync The soldering and desoldering The new counter has two chan-priced Crotechrange of separation circuit; signal delay irons are each outstandingly ef- nels in order to cover a wideoscilloscopes. line for observation of leading ficient, containing ceramic range of frequencies from DCThe cases give proctection for edge of fast risetime signalsheating elements which have to1 GHz. Despite this widethe instruments while being (422); and a convenient X -Y op- positive temperature co- coverage, the counter costs 15-carried about and when stored. eration mode to enable phase efficients giving an 80 Watts 20% less than competitive prod- They are available for 20 MHz, difference measurements be- rating at 350 °C. ucts with smaller ranges. It is2 mV dualtrace3132, the tween two waveforms. The modular construction of accurate to. typically, <0.01% at30 MHz, 5 mV dual trace 3337 and the 30 MHz, 5 mV VDU STC Instrument Services the ELS8000 allows each el- 23'C and sensitive down to ement of the station to be used pulses of 10 mV. mode 3339. Dewar House The Crotech range, which in- Central Road independently and both the Resolution remains high at both soldering and desoldering sec- high and low frequencies. Atcludes both single and dual Harlow trace types, is available with a Essex CM20 2TA. tions are available with digitalleast 7 digits are displayed for displays. a one second gate time, anduseful selection of accessories Telephone: (0279) 29522 to improve further their ver- Telex: 817202 STCRES G Toolrange Limited 5 digits for a 60 ms gate time. satility. (3678:3) Upton Road The gate time is variable from ECW offers the carrying cases Reading RG3 4JA. 60 ms to 10 s or ten periods of input, whichever is the longer. at a price of £37.38, including Telephone: (0734) 29446 post/packaging and VAT. Telex: 847917 (3662:4:F) The counter will be of use to Soldering and thoseinvolvedintestand MostCrotechoscilloscopes measurement both in educa-now include a built-in compo- desoldering tional establishments. and innentcomparatorforrapid testing of semiconductors and problems passive devices. Several types, including the 3132 and 3339, solved in one also provide a very convenient The ERSA ELS8000 is a new in- front -panel +12 V and +5 V out- dustrial soldering and put. desoldering station from Electronic & Computer Toolrange which enables Workshop Limited highlytemperaturesensitive Unit 1 components such as FETs and Cromwell Centre MOS ICs to be worked on in Stepfield perfect safety. Witham Both the soldering and Essex CM8 3TH. desoldering stations are elec- Telephone: (0376) 517413(3678:4) 69 EE December 1987

PRODUCTS NEW PRODUCTS NEM1

Hand held set measurements in any func-0.03 CV or5 mA. The CEL from flight Electronics Limited. tion or range. Readings arerange is suitable for operation A highly sensitive instrument, it digital displayed as a + or - deviation overthetemperature range offers good price performance fromthestoredvalue. The -25 to +85 CC except for 450 V and a resolution of1 mV/div. multimeter 8060Awillrememberthe devices which are rated for op- with better than 3 percent ac- proper function and range for eration over -25 to +70 CC. curacy. measures fre- the value stored, even if theThe CELP2 with plug-in ter-The scope has a 6 in screen user changes functions. minations is a family of low pro- with an internal graticule CRT. quency Other features include overloadfile devices and is available in Availablefunctionsinclude protectionto ElectronicBrokersofferthe 1000 V, DC or the capacitance range from 220 chop/alternateand hold -off Fluke 8060A series of handheld 750 V AC and to 500 V (resist- to 15,000 uF. Working voltagestimebase. The time base range ance);asophisticatedself - range from 16 to 200 V and the digitalmultimeters,thefirst spans 0.2 us to 0.5 s. Both chan- digital handheld test instrument diagnostics procedure; and the devices are suitable for oper-nels have an alternate trigger- ationoverthetemperatureingfunction. A tooffer frequency measure-ability to display AC or DC separation ment capabilities. Ranges in- voltage measurements directlyrange -40 to +85 'C. Capaci- circuit provides TV synchronis- indB.,clBm (referencedto tance toleranceis -10+30% clude200 Hz,2000 Hzand ation. Channel one has a signal 200 kHz, all of which are fully 600 Q),orrelativedB,thus whilst maximum leakage cur-output at the rear of the in- autoranged, thereby enabling allowingsimplifiedamplifierrent is 0.02 CV or 3 mA. strument. easy servicing of a wide range gain tests. The CEL solder tag devices are supplied with of communications equipment. Electronic Brokers Limited mounting brackets already fitted. Theinstrumentsare also 140-146 Camden Street suitable for other applications London NW1 9PB. Availablefromstock,these in design, manufacturing, and Telephone: (01 267) 7070 electrolytic capacitors are part of a recent franchise agreement field servicing. Telex: 298694 Fax: 01-267 7363 (3662:3:F) between Abacus and Wimpey- Dubilier. Abacus Electronics Limited Abacus House Bone Lane Newbury New large can Berkshire RG14 5SF. electrolytics Telephone: (0635) 36222 (3662:9:F) AbacusElectronicshasan- nounced the availability of a new range of large can aluminium electrolytic capacitors. The CEL and CELP2 ranges are manufactured by Wimpey- The unit is easy to operate and Dubilier and are supplied with Low-cost ideal for general purpose work solder tag or plug in termina- 20 MHz dual- in education, service and pro- tions respectively. duction. Trigger modes can be The CEL solder tag termination beam oscil- set at three levels, normal, auto- capacitors are available in the matic, and single. capacitance range from 1000 to loscope Frequency bandwidth is 47,000 uF with working voltages AC/DC 10 to 20 MHz. Rise times from 6.3 to 450 V. CapacitanceThe new GOS-522 dual -beam are 17.5 ns (20 MHz) and 23 ns toleranceis-10+50% andoscilloscope is now available (15 MHz). Chop frequency is around 250 kHz. Overall dimen- sionsare 460 x 310 x170 mm. With a basic DC accuracy of Standard unit priceis£299. 0.04%, the multimeter measures With two switchable probes the AC and DC voltage and current, price is £319. resistance, and continuity and Flight Electronics Limited includes a diode test function. Flight House The 8060A has a 10 ouV, 10 nA, Ascupart Street and 10 mQ sensitivity with ex- Southampton SOl 1LU. cellentstabilitytotheleast Telephone: (0703) 227721 significant digit. A wideband Telex: 477389 FLIGHT G true RMS AC capability enables Fax: (0703) 330039 (3662:15:F) accurate measurements of non - sinusoidal signals from 12 Hz to 100 kHz. The 8060A DMM also features a relativereferencecapability that provides for relative or off- EE 70 December 1987 ItEADERS SERVICES READERSSERVICE1

PARTS & BOOKS BOOKS No. Price VAT ADVERTISEMENTS All orders must be sent BY POST to (Cl (El Eektor ElecrruniCs is pdblisted on the trird oscilloscope 85125 8.451.22 Thursday of the month preceduno cover our Brentford office using the appro- The following books are currently priate form opposite. Please note that Unhorse! control For date. Closing date for copy is five weeks stepper motors 87003 15.40 2.31 before publication date for both colour and we can not deal with PERSONAL available: these may be ordered from certain electronics retailers monotone. CALLERS, as no stock is carried at the FEBRUARY 1987 or bookshops, or direct from our The Publishers will not be liable for arty editorial offices. The postal address is Mobile studio unit 86047 21.00 3.15 toss occasioned by the failure of any given at the back of the form. Brentford office. Electron ROM card 86089 5.70 0.85 advertisement to appear from any cause All prices shown are net and customers VLF add-on unit for whatever; nor do they accept liability for oscioscopes 86135 5.05 0.76 printers' errors, although every care is in the UK should add VAT where 301 Circuits £6.25 Digital sine -wave 302 Circuits £6.25 taken to avoid mistakes. Advertisers' prop- shown_ ALL customers must add generator 87001 7.501.13 erty. artwork, etc. is held at owners' risk. postage and packing charges for orders 9968-5 2.05 0.31 BINDERS and should be insured by them against fire or other damage. up to £15.00 as follows: UK, E1_00; MARCH 1987 Europe, £1.50; other countries, E2.00 Elektor Electronics binder £2.95 Copy and illustrations are in all cases sub- MSX'EPROMmer 87002 9.501.43 ject to the Publishers' approval and must !surface mail) or £3.00 (airmail!. For Valve preamplifier 1 87006-18.501.28 FRONT PANELS comply with the code of advertising prac- orders over £15.00, but not exceeding 86111-3a 6.901.04 tice in force in the country or countries of £50.00. these p&p charges should be Stereo VI) meter 87022 1.750.26 publication. The advertiser will indemnify No. PriceVAT Siphaser 87026 8.201.23 doubted. For orders over f50.00 in (0) (C) the Publishers against any contravention of value, p&p charges will be advised. APRIL 1987 any Trade Act in force in the country or Indoor unit for satel- coutries of publication. The Publishers lite TV reception 86082-F3.500.53 Valve preamphitu-2 87006-2 12.521.68 Software is also available from Facsimile interface 87038 8.831.32 reserve the right to re'...Ere -_spend, or Top -of -the -range 86111-F1 5.600.84 7 TECHNDMATIC LIMITED (for address. Learwitz liters 84071 7_261.09 cancel any advertise- - " .."_6e.5 of see inside front cover). preamplifier 86111-F2 4.450.67 advertisements. In .1 - no Digital sine -wave MAY 1987 Putilishers' Ste,-e.__': -75.-;Business In Sweden. printed -circuit boards generator 87001-F5.450.82 CanAirriance note 86042 5.150.56 apply (see re,e-Ee & Books Order should be ordered from Autoranging 13M1.1 87099-F2.800.42 Metal detector 86069 4.250.64 Form opposite.. T- of space reser- Frequency meter 87286-F 10.751.61 MIDI signal distribution87012 7.401.11 vations by the advertisers or their agents is ELECTRONIC PRESS deemed by the Publishers to imply accept- Box 63 Spot sine wave SOFTWARE generator 87036.t not avalable ance of, and agreement to be bound by. S-182 11 Danderyd these conditions. Telephone: 08-753 03 05 Software in lEIPROSts No. PriceVAT JUNE 1987 (El (El Intercom for motor 0P -controlled frequency cycfrsts 87024 6.851.03 Advertisement sizes SUBSCRIPTIONS meter 1x 2732 531 9.001.35 Spot sine Vralfe Tnm size: 297mm a 210mm Subscriptions can be provided X -Y plotter generator 2 87036-2net alai** Full page: 265mm a 185mm page : 130mm x 185mm Moriz) anywhere in the world: they may be 1 x 2732 532 9.001.35 Autoranging 0/.0.4 87099 6.55 0.98 programmable timer 265mm a90rnm (yen) ordered on the appropriate form op- JULY/AUGUST 1987 is page : 63mm a 185mm Manz) 1 535 1.35 posite_ a 2732 9.00 GHz pre -scaler Wien bridge oscitator 87441 2.15 0.32 130mm .90rnm (vert) Duty factor analyser 874.48 5_85 0_88 1 x 2732 536N9.001.35 % page : 63mm a90nun automate your Digital voltage:currern Classified & semi -display column width: LETTERS model railway display 87468 6.50 0.98 60mm 32 K pseudo ROM 87500 4.00 0.60 1 x 2716 537 7.30 1.10 Full pageibleed size: 303mm a 215mm Letters of a general nature, or express- marine computer Headphone amplifier 87512 9.001.35 Halogen lamp drnmer 87452 not ayalatte ing an opinion. or concerning a matter 1 x 2716 538 7.30 1.10 of common interest in the field of elec- Jumbo clock 7-digt code lock 87463 not ar-itable Production details Printing :offset tronics, should be addressed to The 2 x 2716 53914.60 2.20 SEPTEMBER 1987 Graphics card Screen, : 40:cm (100 inch) Editor. Their publication in Elektor Elec- Surface -mount stereo colour 601crn (150.inchl 2 x 82S123 543 9.60 1.44 FM receiver 87023 3.20 0.48 tronics is at the discretion of the Editor. printer buffer Required material :Irtho artwork or 16 Kbyte CMOS RAM same size wrong - 1 x 2716 545 7.30 1.10 for C64 87082 4.10 0.62 PAST ISSUES MSX EPROMmer reading negatives Active phase-Imear (mono) 1 x 27128 552UK 7.30 1.10 liter 87109 15.00 2.25 A limited number of past issues can be EPROM emulator colour separated EPROM emulator 87136 17.50 2.63 film positives and supplied at the current cover price plus 1 x 8748)4 55815.00 2.25 progressives postage & packing as detailed above. OCTOBER 1987 Icolourl PRINTED CIRCUITS IEEE interface 87054 11ot evadable Agency commission: 10% SS9 adapter 87145/lot available TECHNICAL QUERIES Raiders who wish to mate their men 14-bn 0-A convener 87168 7.251.09 PCBs ire; private and personal use orly) Reconfirm playback Although we are always prepared to Advertisement rates assist readers in solving difficulties they may in many, but not all, cases receive amplifier 87486 Not evadable the relevant drawings free of charge by Low -noise microphone Full page £440.00 may experience with projects that have ordering these on the order corm opposite amplifier 87058 3.455 0.52 Half page £245.00 appeared in Elektor Electronics during and enclosing a stamped addressed Quarter page £145.00 the PAST THREE YEARS ONLY. we envelope (preferably 9,13 In or NOVEMBER 1987 Eighth page £95.00 230 x 325 mo). 558 Receiver for 80 m Special position regret that these can not in any cir- or facing matter + 15% cumstances be dealt with by telephone. and 20 m 87051 14.752.21 BASIC computer 87192 20.25 3.04 Cover position 25% Bleed 10% 40. Price VAT (Ammer for inductive loads 87181 6.00 0.90 Additional colour E200.00 COMPONENTS IC) Ill IR Transceiver 87179liot avaaiae Classified ads 45 p per word Components for projects appearing in JANUARY 1987 (Mill 12 words} Elektor Electronics are usually available IOU for satellite TV DECEMBER 1987 Semi display ads £10.00 per single from appropriate advertisers. If difficult- reception 86082-36.901.04 Digital motor enver for column cm (min 2.5 cml Top -of -the -range RC models 8709B 4.50 0.68 Series discounts are available on appli- ies in supply of components are en- preamplifier 86111.2 22.50 3.38 Frequency meter 87286 12.501.89 cation. visaged, a source will normally be MSX cartridge for t. LCD VU meter 87505 6.751.01 All prices are subject to VAT at the stan- advised in the article. oscilloscope 85125 8.451.22 87520 6.751.01 dard rate.

EDITORIAL CALENDAR

Publication Copy deadline Issue Main theme date Advertisements* Articles January 1988 17 Dec. 1987 9 Nov. 1987 26 Oct. 1987 HF & VHF Techniques February 1988 14 Jan. 1988 4 Dec. 1987 20 Nov. 1987 Telecommunications March 1988 18 Feb. 1988 15 Jan. 1988 28 Dec. 1987 Sensors April 1988 17 Mar_ 1988 12 Feb. 1988 29 Jan. 1988 Electrophonics May 1988 14 Apr. 1988 11 Mar. 1988 26 Feb. 1988 Artificial Intelligence June 1988 12 May 1968 8 Apr. 1988 25 Mar. 1988 Electronics & An July/August 1988 16 June 1988 13 May 1988 29 Apr. 1988 Amateur Radio & TV September 1988 18 Aug. 1988 15 July 1988 1 July 1988 Computers & Microprocessors October 1988 15 Sep. 1988 12 Aug. 1988 29 July 1988 Power supplies November 1988 20 Oct. 1988 16 Sep. 1988 2 Sep. 1988 Optoelectronics December 1988 17 Nov. 1988 14 Oct. 1988 30 Sep. 1988 Computer -aided test & measurement January 1989 15 Dec. 1988 11 Nov. 1988 28 Oct. 1988 Audio & Hi-fi February 1989 19 Jan. 1989 5 Dec. 1988 21 Nov. 1988 TV & video March 1989 16 Feb. 1989 13 Jan. 1989 30 Dec. 1988 Knowledge -based systems April 1989 16 Mar. 1989 10 Feb. 1989 27 Jan. 1989 Telecommunications May 1989 20 Apr. 1989 17 Mar. 1989 3 Mar. 1989 Robotics 'Ore week later for camera-ready copy. EE December 1987

PARTS & BOOKS SERVICE

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TERMS OF BUSINESS How to order ing at the time your order is re-nents, and so on, described in our Orders for parts and books shouldceived: these cheques should be in-magazinesorbooks.The pub- be sent to creased by the equivalent of £3.00lishers do not accept responsibility ELEKTOR ELECTRONICS to cover the Bank's negotiating fee.orliabilityfor failingto identify 1 HARLEQUIN AVENUE such patent or other protection. GREAT WEST ROAD Delivery BRENTFORD TW8 9EW Whilst every effort will be made to ENGLAND dispatchyour orderwithin2-3Copyright Enter the details of your order, cutweeks from receipt of your instruc-All drawings, photographs, articles, outthe completed orderform,tions, we cannot guarantee thisprinted -circuitboards, EPROMs, enclose your remittance where ap-time scale for all orders. and cassettes published in Elektor propriate, and post. Electronics (other thaninthird - Returns party advertisements)are copy- How to pay Faulty goods or goods sent in errorright and may not be reproduced or Unless you have an approved creditmay be returned for replacement ortransmitted in any form or by any account with us, all orders must becorrection, but please do not returnmeans, including photocopying and accompanied by the full payment,goods for refund without obtainingrecording, in whole or in part with- including VAT (where applicable)our prior consent. All goods re-out prior permission of the pub- and postage and packing chargesturned should be packed securelylishers. Such written permission as stated under "Parts & Books" inin a padded bag or box, enclosing amust also be obtained before any the Readers Services section. covering letter stating the dispatchpart of these publications is stored Payment may be made by cheque,note number.Ifthe goods arein a retrieval system of any nature. postal order or ACCESS (in the lat-returned because of a mistake onNotwithstanding the above, ter case, the order must go to theour part, we will refund the returnprinted -circuit boards may be pro- cardholder's address). Do not sendpostage. Goods returned for refundduced for private and personal use cash through the post. Chequesmust be in a resaleable conditiononly without prior permission. and postalordersshould beand will be subject to a ten per cent crossed and made payabletohandling charge, with a minimumLimitation of liability ELEKTOR ELECTRONICS. charge of £1.50. If you live outside the UK, payment The publishers shall not be liable in contract, tort, or otherwise, for any may also be made by Bankers Ster-Damaged goods ling Draft drawn on a London clear- loss or damage suffered by the pur- Claims for damaged goods must bechaser whatsoever or howsoever ingbank, Eurocheque, US orreceived at our Brentford officearising outof,orin connection Canadian dollar cheque. within 7days(UK); 10dayswith, the supply of goods or ser- Ifyou pay by Bankers Sterling(Europe),or14 days(allother Draft, make clear to the issuing vices by the publishers other than countries) from your receiving theto supply goods as described or, at bank that your full name and ad-goods. dress MUST be communicated to the publishers' option, to refund the London clearing bank. the purchaser any monies paid in Cancelled orders respect of the goods. Eurocheques should be made out inAll cancelled orders will be subject £ sterling and have the holder'sto a ten per cent handling charge, guarantee card number written onwith a minimum charge of £1.50.Law the back. US and Canadian dollar Any question relating to the supply cheques, as well as EurochequesPatents of goods and servicesby the not made out in £ sterling, are ac-Patentprotection may existinpublishers shall be determined in all cepted at the exchange rate prevail-respect of circuits, devices, compo-respects by the laws of England.

GENERAL INFORMATION & CONDITIONS OF SALE Subscription rates Eurocheques should be made out in E sterlingMissing issues United Kingdom E18.00and have the holder's guarantee card numberReplacement copies will be sent within reason, UK students £16.50written on the back. US and Canadian dollarprovidingclaimsarereceivedwithin two Europe & Eire £22.00cheques, as well as Eurocheques not made outmonths (outside Europe & North America - Outside Europe - surface mail £22.00in E sterling, are accepted at the exchange ratethree months) of the publication date of the AIRMAIL: prevailing at the time your order is received:missing issue. Requests for issues beyond this Middle East & North Africa £28.00these cheques should be increased by theperiodshould be addressed South East Asia tothe Back E32.00equivalent of£3.00 tocover thebank'sNumbers DepartmentofELEKTOR ELEC- Central & southern Africa £32.00negotiating fee. Central & South America TRONICS who will advise the cost of replacing £32.00DO NOT include payments for other services:the issues concerned. USA & Canada £32.00to do so will cause serious delays both to your Australia & New Zealand £34.00subscription order and the other services. Far East & Pacific £34.00 Subscription period Cancellations How to pay Cancelled orders will be subject to a fee of Unless you have an approved credit accountThe standard subscription order periodis twelve months. If a permanent change of ad-25% of the full subscription price (minimum with us, the order must be accompanied by £5.00) plus the cost of any issues already payment infull. Payment may be made bydress during your subscription period means that copies have to be dispatched by a moredispatched. Subscriptions can not be cancelled cheque, postal order, ACCESS or VISA Ac: in when they have run for more than six months. the last two cases, the subscription must go toexpensive service, no extra charge will be the cardholders' address. Cheques and Postalmade. Similarly, no refund will be rnade nor ex- Orders should be crossed and made payable topiry date extended, if a change of address allows the use of a cheaper service. ELEKTOR ELECTRONICS. Miscellaneous If you live outside the UK, payment may also be Student applications must be supported by made by a Bankers Sterling Draft drawn on aChange of address evidence of studentship signed by the head of London clearingbank, Eurocheque, US orAt least six weeks advance notice is needed tothe college, school, or university faculty. Canadian dollar cheques. If you pay by Bankersensure that copies reach the new addressPlease note that new subscriptions take about Sterling Draft, make clear to the issuing bankwhen required. Please enclose the address por-four weeks from receipt of order to become ef- that your full name and address MUST be com-tion from your mailing wrapper when sendingfective. It is regretted that new subscriptions municated to the London clearing bank. in your instructions. can under no circumstances be backdated. 111EE December 1987 PRODUCTS NEW PRODUCTS NEVl

Rugged, £34.65 exc. VAT. Microcomputers for LCD and244 uV increments and +10 V Model 3015 inc. carrying casebattery drive and Application DC in 2.44 mV increments. accurate & £40.12 exc. VAT. Specific ICs. The hexadecimal mode is most Universal Instrument ServicesHero Electronics Limited usefulfor computer -oriented protected Limited Dunstable Street calibrationofdigitalpanel Unit 62 Ampthill meters, A -to -Ds, and data ac- Two new analogue multimeters GEC Site Bedfordshire MK45 2JS. quisition systems. It eliminates are available from Universal In- Cambridge Road struments. Hioki models 3000 Telephone: (0525) 405015 the need for tedious hexa- Whetstone number and 3015 are high quality instru- Telex: 825906 (3662:8:F) decimal -to -decimal Leicester LE8 3LH. conversions as the DVC-350A ments that are drop proof, have Telephone: (0533) 861544 performs these automatically. large clear taut band suspen- Telex: 34611 sion meters with diode Fax: 0533 866084 overload protection and can (3678:9:F) withstand 240 V on all resist- Hand held ance and current ranges. Both voltage AC and DC voltages are accurately measured to1000 V calibrator with a DC voltage sensitivity of 20 kQ per volt. Modem Datel has introduced a new evaluation hand-held battery -powered voltage calibrator for precise board adjustment of analysers, recorders, controllers, data ac- Recently introduced by SEIKOquisition system computers and EPSON and available through many other lab and field appli- theirU.K. Agent Hero Elec- cations. tronics, is the SEK9401B Modem The microprocessor -based Evaluation Board. Intended as a DVC-350A provides the user tool to helptheDesign with two entry modes of oper- Engineer evaluate the SEIKO ation and four output voltage Other features of the DVC-350A EPSON range of CMOS ranges. The outputs feature an include a 41/2 digit LCD; right and left binary shift for hexa- Telecom LSI,itincorporates outstanding 0.015% accuracy, a 300 bps and 1200 bps Modemfigure more usually associated decimal calibration of A -to -D or D -to -A converters; convenient, ICs, a DTMF Tone Dialler, Pro- with laboratory -type cali- easy -to -usemembranekey- Hioki model 3015 also measures tocol Controller and 8250A/B brators. The accuracy and stab- both alternating and direct cur- Compatible Bus Interface. ility are traceable to the US board with audible feedbacic rent to 10 A, resistance to 15 MQ The SEK9401B is capable of full - National Bureau of Standards. up to 20 mA source or sink cur- rentcapability;finger touch infour ranges with a 20 Q duplex communication at The DVC-350A possessesa centre scale, dBs from -10 to 1200/300 bps on a telephonenumber of powerful features cursor control with automatic +23 dB and temperature with line. Connecting it to an IBM such as switch -selectable mode voltage increment or decre- an optional probe from -30°C PC-XT/ATSystembus im- of entry as either decimal orment; and automatic current to+200°C and isthe ideal plements a complete modem hexadecimal.Decimal modelimiting and low battery indication. general purpose tool. Model link. output ranges are ±1.2 V DC in 3000 measures direct current to HeroElectronicsrepresents100 uV increments and +12 V The DVC-350A features rated 300 mA, resistance to 1 MQ with Seiko Epson in the U.K. and of-DC in1 mV increments. Hexa- accuracy down to 6.5 V DC bat- a 20 Q centre scale, tempera- fers their range of CMOS LSI.decimal mode offersoutput tery level using reachargeable ture via an optional probe from This also includes SRAMS, 4 bit voltage ranges of +1 V DC in 7.2 V battery or conventional -50°C to +150°C and has a real 9 V battery. The calibrator is battery test function with an in- supplied with water resistant tegral load to indicate the true carrying case which also holds condition of the battery under the test leads set and spare bat- test. teries. A certificateof NBS Both instruments have a Traceabilityandoperations physical size of 136 x 92 x manual complete the package. 39 mm, and come ready for use Datel UK with test leads, spare fuse, bat- Intec 2 Business Park teries, instructions and carrying Wade Road case. A range of usefull optional Basingstoke accessories includes a clip -on Hants RG24 ONE. ammeter with a0to 300 A Telephone: (256) 469085 range, a 30 kV high voltage Telex: 858041 INTDAT G probe, thermistor temperature (3678:12:F) probes, and a fused probe for power line voltage measuring applications. Model 3000 inc. carrying case EE December 1987

EXPORT ULTRA HIFI CLASS A 744664° FACILITIES POWER AMPLIFIERS emicrotiti170536 WORLDWIDE ce-s.r.ed fee Lott -nog to VIII*St 24 rho. advanced acthe Claims A MOSPET coact hr 7 days/week , to 54539 ON PetIO,OZIOOG 9O 150W 091 4-16ohntL or* Leraaue morkde * * * 74TT1 117 40 .55.- 0.COIX 4O iL.:-,-2 5: VEYDRES LS HC 158 40 ES OPO7CP 55 TL032 45 DRAM 5V NMOS There'sfrraother arrpfifier module that cattalo. ANY of these ad 00 2) 25 161 55 55 fiE5 18TE084 45 4164 641K . 1 EC/ 88 (0 23 25 163 55 55 11.074 50ULI,C.O:1 73 41256 256K . 1 (2.39 THE 'SUPERMOS',...d 04 20 25 164 55 55 4416 te)1 =I E3 30 41464 64K . 1 £3.30 Ce 20 25 IF2 ...,00 75 SAVE OVER 40% ON OUR 20 Z '''. '-'-' EX EQUIPMENT MEMORIES SRAM 5V HMOS Actne days A MOSFET O. P (cool runn.e.21 10 20 FLOPPY AND EPROMS 11.93 2114LP 1K a * DotorOon typicady 0.0002% 1201art) 14 20 23 DISC CON i Dor s of 4,:n...... 1 215LP Z( 8 1250 20 20 23 TF1OLLERS * Slew rate greater than 250Wpa or-tare's * 16gh current Cassaba:v. of sox -ma p -p 21 20 29 02157 19.0) GUARANTEED UV SRAM 5V CMOS 27 27 WD1797 1900 ERASED AND TESTED 6116LP 2Xt8 (1.40 ntsgral atink. no * Very low feedback for superb sound goakty 42 49 WII.V16 14 6264LP EX .8 (2.50 *Lli-Owe gan vac* for exceotioal porker supply 4116 1(s: .. "5 10,75 o rternd comporents 7812 23 62255IP 326.8 C14. 0 51 20 25 EPROMS E rr.p4 rnorsns onto a flat opple rejection 74 20 33 765412 3) 93 2716 2K. 9 C1.50 EPROM SV NMOS .sneL 35 59 75154 2732 4K , 8 E1.E0 2716 21( 8 (2.70 ts -430 to 1543VDC fLd deals with each *ma*: 141.*Ialare wparale4y. E2_50, reorder. 38 20 49 ADC0333 SW F-SU 276A. 6K E El 20 2732 411 8 L2.65 In ea ss LM311 AO 27128 16)1 8 C2.50 2764 EX 8 C2.45 Ire ultinate in class A scond quaky at a fraction of the cool of butt units. SUPERMOS rnockd 132 49 15024 43 271284 16K 8 E2.70 t35 43 40 1.1.037 1.23 AS taken from working each Iota inc. SAE or 4 IRCs for detzds. 27256 326 8 (3.75 etc) £21.00 '33 40 43 1).1348 5 boards. Try some. You will - Low Noise Duo Regulator for Pre Arrives 27512 5,7,, 5 (9.70 ideng £5 per pal -Europe. £12 5.i Al t... [AMR 4E SAVE POUNDS ELIE E XPO Riots sr,--"ty - send 50* draft in meting drawn on a tro-rOc- rma-Par EL, et. ADD VAT 15 i ORDERS UNDER £25 ADD El P&P OVER £25 POSTAGE FREE ORDERS DISPATCHED SAME DAY BEFORE 3.30 PM Construction House, Whitley St, DEPT (E 1) 18 HOLDERMF_ADOW Av CORBY NORTHANTS NN18 9AI SPICE Bingley, Yorks. (0274) 568647 00 D. P. HOBBS (NORWICH) LTD. Deansgate Electronics 13ST. BENEDICTS STREET (G 3HEO) We stock a large range of electronic components. NORWICH, NORFOLK NR24PE test equipment. telephone accessories, computer Tel.0603 615786 accessories. microphones. mixers. meters. stylus. So Electronic component specialists call in and have a look around. Amateur radio equipment 263Deansgate, Manchester Piexchanges welcome -- Access. B/Card Telephone:061-834 1185 Open 9 a.m. - 5.30 p.m. Mon - Sat. ThursCas 9 - ip_r, ELECTRONICS KITS & COMPONENTS ENORTHERNL ESUPPLIESCOMPONENT SPECIALISTS 13 BOSTON RD Test Equipment, Computers. Peripherals LONDON W7 3S.1 also at SHAWCLOUGH ROAD, Tel. Orders:01.551 0110 Enquiries: 01-5219754 45 LOWERHILLGATE, WATERFOOT Shc.p Hours:Mon-Fri 9arri-ipm STOCKPORT,CHESHIRE. ROSSENDALE 684 9JZ. Sat 10arn-4pa. 061477 9272 0706 - 215556 ELECTRONICS BRADLEYMARSHALL- omNI stock a wide range of electronic components a: ELECTRONIC COMPONENT 174 Dalkeith Road COMPUTER & SOFTWARE SPECIALIST Edinburgh EH16 5DX tel: 031 667 2611 BRADLEY MARSHALL. 382-386 EDGWARE ROAD. LONDON W2 1EB Telephone: 01-723 4242 situatedmidway between Commonwealth Pool and Cameron Toll.

GARLAND BROS. LTD ECTRONICS LTDDOD Electronic Components Spec alists ...... 40 CRICKLEWOOD BROADWAY Chesham House. Deptford Broadway, London, LONDON NW2 3ET SE840N ELECTRONIC 01-452 0161101-450 0995 TI x : 914977 COMPONENTS Telephone 01-692 4412

LTD.102 CHURCHFIELD ROA 99D. ACTON. BON EX LONDON W3 6DH 01 2 7748 L.F.HANNEY

Toko coils filters chokes and inductors Ms. 77LowerBristolRoad, Bath, Avon. Moulded coils linear TTL CMOS XTAL filters Helical and ceramic filters RF transistors Tel.0225-24811 Radio communication IC's Toko block fillers Your electroniccomponentspecialist for Avon, Wilts. & Somerset. Not just a component shop but a whole lot more. Closed Thursdays Trade Et OEM .ts. available ex stock. CAUDIO ,-...-.., ELECTROnICS AFT ARLE0 GEu _--i Era Stout 404EdgwareRoad,London W2 lED iMarshall'si-___.',.i-fp.....s TEST ,-4s a 2 COMMUNICATIONS INSTRUMENTS PCERT3HPUEMTERLS c=7;17-TII'2'aml-25 Judge us by the company ..ve keep - 1,6.00,1E100 PA - DISCO Siemens, Texas, National. Muliard, Leader, ITT, SECURITY Global Specialities. Piher, Sinclair/Thandar, Greenwood. ACCESSORIES Arrow, Antex, Sifarn, Vero, Motorola OPEN6 DAYS A WEEK: 01-724 0323/3564 PROGRESSIVE RADIO PLEASE MENTION THE ELECTRONICS SPECI A LISTS' ELEKTOR ELECTRONICS AenaisiComponents/Ham & CB Radio - a fully comprehensive range. WHEN CONTACTING 93 Dale Street, Liverpool L2 2JD. TeL 051 236 0982 ADVERTISERS Also at 47 Whitechapel, Liverpool. TeL 051 236 5489 112EE December 1987

WANTED: Editor assembler for Tandy EPROMSIRAMS, new 2764K, Colour Computer and any peripheral 27128K-2, 6264LP-10, 4256-15, E2 hardware. Please write or phone: Mr ea. Any 6, £10. incl. P&P. BBC chips, G. Moodie, 44 Seafield Road, Edin- PROMS blown:copy SAE Mr R. WITaBOAR burgh EH6 7LQ. Tel. 031 553 7827. Wraight, 30 Swains Road.Tadley, Hants. RG26 6LZ. Tel. 07356 77353. OFFERS for complete set of Elektor POWER SUPPLY 150W =5V at 8.5A, OLIVETTI PORTABLE COMPUTER and from issue 1 to 80 (Dec 74 - Dec 811. 12V at 4A, - 24V at 1.7A, -12V at Plotter. unwanted gift. Offers invited. Bladon, 15 Burfield Road. Leigh on Sea WANTED: Any 6 metre Transceiver 0.21, over voltage, over current pro- to include manual and charger, word SS9 5TU. gear, also photostat or service manual tection, £19. Tel. 0245 259027. proc., clock. A. Miller. 8 Middlentist Solartron CX1441 scope. Lucking. 62 Grove. Great Barr, Birmingham 843 Ember Farm Way, East Molesey. Surrey WANTED: SSB Adapter for Grundig KT8 OBL. Tel. 01 398 3603. EDDYSTONE EA12, amateur band re- 5EJ. Tel. 021 358 1843. -Satellite Radio Receiver, Model 2100. ceiver, as factory condition, as new Tel. Darlington (0325) 381075. with manual. f130 o.n.o. W. Billington, GEORGE BRAY LTD brass encased ORGAN PARTS Gen-BDS rhythm unit 16B Wyleu Street, Honor Oak Park, heating elements for sale, total quan- WANTED: Crystal set Galena revert i Korg synth etc. All London SE23 1DU. Phone 01 699 tity 18 assorted lengths & wattages. reasonable. Sean Smyth, "De Porres". 4413 after 6 pm. 170 - 1150W. Offers invited.E.G. Catswhisker detector. Cosgrove. 59 Fenton Road, Southbourne, 67 East Princes Street, Helensburgh Priestley, 6 Lynden Avenue, Windhill, G84 70G. Scotland. Tel. 0436 71181. IC CLEAROUT: 74LS95. 161, 192.4. Shipley, West Yorshire BD18 1HF. Tel. Bournemouth, Dorset BH6 58S. 290, 366, - 40p; 78M05112 - 25p: 0274 593382. LM318, CA3146 - 75p; CA3130, OFFER: Handicraftiware,folkLPs, HAS ANYONE BUILT synthesised UA733, LMICA)339 - 35p: - lots WANTED: Any complete circuit mountain holiday in exchange for full shortwave radio 144 rots transceiver. more. Rick Beament, 10 Shakespeare diagrams of Transceivers. CW, SSB, sat. recept. unit kit & Sony SMC70GP (Practical Wireless). John Savage, 18 Gdns, Cove. Farnborough.Hams, etc. Nothing overly complicated. Will PC. Big HURRY( Bohm Ernest Francisc, BidefordClose,Pknorth,Swindon, GU14 9QT. Tel. 0252 540558. pay reasonable price. R. Parker, 'Dail', Strada Romaneasca 1, BL. 46, SC. 11. Wilts. SN3 2LB. Burford Road, Lechlade.Glos. GL7 AP 20,R-2692 Vulcan -HD, Jud. WANTED: Service manual anclor data 3ET. Tel. 0367 52493. Hunedoara, Romania. for Rediffusion system Alpha 14 inch SALE: Solartron double beam oscillo- FOR SALE:Telephoneline micro scope 10MHz, delay tirnebase. £75. display monitor. Tel. 0737 221480. SOLARTRON spares for sale. Tel. Lon- transmitter, E10. Voice micro transmit- don 101) 747 1635. Phone D.E. Jones. 01 249 4829. WANTED: RTTY Unit (DIY) kit -4- soft ter, £12, size 35 x 15 15. SAE for warefor Acorn Electron. Anything list. lzhaki Jouval, 10 Zvi Pinkas St, considered, any information on RTTY OR-Jhoola, Israel 60-201. WANTED: Elektor from January 1985 for Acorn welcome. P.A. Webster, 1 to June 1987, and Hewlett Packard Louden Cottages,Pitfour,Mintlaw, WANTED: AppleII Language Card. catalogue1974 or1975.Maiorino Aberdeenshire AB4 8LE, Scotland. Write to Robert Bolton, 29 Ettore, Via Atemo 53, 66013 Chieti Ballineaspig Lawn, Bishopstown. Scalo. Italia. WANTED: Circuit diagrams of Cork. Ireland. DMS1280 Data Terminal. Willing to pay. Write to C.R. Rosli,11 Lebombo CLEAROUT: 3printers& VDUs, 51/4" DISC DRIVES. 2 off, 40T full Place, Glenvista EXT5, Johannesburg, EPROM programmer+ flext6800 height TEAC FD 50A, £35 o.n.o. Gary S. Africa. system. Zicon 701 Logic Analyser, os- Morgan, 61A Roxborough Road, Har- cilloscope & drawing board. Vidya rev:, Middlesex HA: 1NS. Tel. 01 861 FOR SALE: Oscilloscope with flat LED Thillai. 74 Forlease Road, Maidenhead, 2210. screen (unmade kit),£29.99. Also Berks. Tel. 0628 36121. case kit, £9.99. Scope lead. £3.95. SPECTRUM 48K Computer, Interface Newbrain AD Computer,£40.J.E. DISC DRIVES: two 8 inch DS drives. & Programs, £75. Talkingboard Ellis, The Flat,18 Butter Hill,Wall- FWO with manuals. E100 o.n.o. Tel. SpeechSynth, E35. SpringLine ington, St.16 2JD. Robert, 0203 317360. evenings. Revert, £23. Tel. 0502 66026.

I am a private reader.I have read your rules and I enclose a valid switchboardvoucher. Please place the following advertisement, free, in the next available space.

BLOCK CAPITALS PLEASE ONE CHARACTER TO EACH BOX. advertising forour readers!

Rules: Private advertisers only. No trade, no Name and address business. Full address or private telephone number; no post office hoxes. Items related to electronics only. Software only when related to Elektor Electronics computer projects. Maximum length: 114 characters - letter, numeral, comma, space. etc. (not including address and;or telephone number). One advertisement per reader per month. To oc:3 enforce this rule, a switchboard voucher will be printed each month. Aerio v 0, Elektor Electronics cannot accept respon- Send to: sibility for any correspondence or trans action as a result of a 'switchboard' ad, nor ELEKTOR ELECTRONICS 4,4b as a result of any inaccuracy in the text. SWITCHBOARD All advertisements must include the AN Ads will he placed in the order in which 1 HARLEQUIN AVENUE voucher printed here_ They must they are received. GREAT WEST ROAD he post -marked within the We reserve the right to refuse adver- BRENTFORD TW8 9EW month indicated. tisements. without returning them. ENGLAND EE December 1987 76

1 BAKERS DOZEN PARCELS COMPACT FLOPPY DISC DRIVE EME-101 NEW ITEMS st1 CC: i.o i_ro, 72 The EME-101 drives a 3- disc of de new standard which despite Some et se .any deicsted 5+. Cut amens 1st +ere. Eck. kral 01c.a..0 ,on - extra bee. es anal we prowfm a capacey of 933k per the, atsch .me par. Al die I.. -:Leis fisted babe. brand new xonipareeds equisakert to the 53:-tic Ur matted s.h. We supply the Oporto, Mensal and error nformaten Vneoer,g 1 -5 13 amp ring train lunetre. boxes bow to use this WM poodar Cancasto5- BSC. Sactrum 12 POUNDERS Amstrad era A3 al a special mks pie 01 127.50 eckning past 291311 orb et doptroork math and demons to reap cat 2 -5 13 a -a .rp main spur bores and VAT_ Data avala4de *vire.* a. refundable if rat archer, 2P122 In roan, bergs- srUce tmacena was area Mob 5 - 3 f , . rai switches ore owe_ 22123.1 ra'ary sks0.00 sa-bse mains owes engagediv\ 7 -4 ci witches with neons sea and off 8 - 280 wan brass cased elinents 22124.1 'hk..Y ansenta 9 -2 mains transformers with 6v la secondaries EVERLASTING BATTERIES, wod not elute, tut 1 stet don't switch 4 22121.1 ,,Kes .s.,-Ttly on No *Au on. the Idiom battery has at :Arced nricf rm. she. Efe, wisch makes 22129.1 - . 115. so aropTrel ribs SaLECCCE w Mr 10 -2 mans transfon.srs with 12v lie secondaries it.. e-rs for emergency. siandbY & sinkar accifostars, eso for quou 22131_1 MN To de Dom Garb= 11 - 1 extension speaker cabinet for 64" spe-akta dots and tamorarts rtut draw my microscopic currents. He 221]21 S. fa fie warring or poems-. 12 - 5 octal bases foe relays or valves khan barker we haw is 3v and about as bg And thick as 2p on 22133.1 ae- Ma. Cate. tel C53 13 - 12 glass reed switer. Prism 2 for EI ref St)553. Note these plug nto D7 socket ax ref 22134.1 or,a mi 13a socket 14 -4 OCP 70 photo tramismrs 130553 rta.122133 ICam 16 - 4 tape heads. 2 record. 2 erase 3 POLE MODEL MOTOR Ad operate born as low as the and mad 2E07.1 IntOcitOtd for treasons Moral tea 17 - 1 ultra sonic trans -nine and 1 t6Ito recta,. wit noose WeaSty as the wortragenormed. at 9e however a 22138 .1 la saga ire rang 18 -2 15000 mid COrreputer grade ebactroles governor rAc+k 05w and the speed rerrans comsat 21'141.1 ; tartar Dsae H Akimbo rag ended en sate motor 2P14210m : a- .ire ?sr.,. PVC 19 -2 ight dependent resistors for molds. Ste appro. 78on 4krs-ri satyr resersid nth Goad 29141.1 20 -5 afferent micro switches Length spole 137p each our ref 1360). 22129.1 21 - 2 main interference suppressors CASSETTE STEREO TAPE HEADS wash rnourti.g test.s end WM 2PH6.1 22 - 225 watt crossover arias 2 way use nudes taus. ore mood: barb.* ad the otter erase_ ET par ref 29147.1 23 - I 40 wan 3 way crossover unit E DW. 2P143.1 : d war tur 21,1de 28 - 1 6 argil counter dais voltage OPTRO INTERRUPTER consists of a IR errata mcontot dose to 2Pi5D.t PSU . 2a. 24 Cc unwind 32 - 2 Fixed battery chargers 19ht Orposierrt motor when Eget or IR is 4worrup,op rho usage 29151 1 Air, a _l111220 pat 31 - 1 key wench with key resistance can same made to Peach a operas a retry 22152. I 32 -2 trunicety snitches useful Mr 22(531 7w, ...00a S.. we Moe coating, motor stoppng etc. Price 2 fa El ref 13050. 2215121 - ekg into 13a ureirs 5.24 -VA 33 - 2 aerosol cans of ICI Dry Lubricant 2915Ra - pilsa bra 13a socies6. 3A of.p.t 34 -W x1 metre lengths colour coded conneetrng VENNER TIME SWITCH 291E...1 gene 16, 17. PS & 20r Wry wires Mans corewel with 20 ores siatrts. are on 221911 1-at+-k1S141 oath IOW CaSsarsall,C0 36 -2 air spaced 2 gang tuning condensors and ow off per 24 Ns repeam defy 22193_1 SCCeria easedtrt cars teed an:1.MA leaf 37 - 2 solid draelectric 2 gang tuning condenses WHil 1 ckg edger feed uteri 3 13a Pup aurceratcaly correcrirg for the lagthrong 22161.1 B" &WW1 side oases 38 - 10 compression trimmers a the shortening day. An expansive tire 291611 Stereo ;Aso* PCB mormia &declass 135 41 -6 Rocker Switches 10 amp Mans SPST went WI year can haw a for cedy 12.95 221631 AC VAIdo9 cleacear 12ut (*De AC or 1110v do 43 -5 Rocker Switches 10 amp SPOT Centre Off without case. metal case - 1225. adaptor 1PTEU1 AC Wala2 mama 1b1350. AC a ED.- do 44 - 4 Rocker Switches 10 amp DPDT kit to careen Mit nip a rarral 24hr. terse _41613 Now kacks 3 otrs berg Casa ore red B T ;kg teat Cril retch but with the added setae -mac of 45 - 1 24 hour tine switch mans operated Is_K1 12 crOoffs Pd tuts. This makes an des 46 - 1 6 has dock ameswitch Ea -Electricity Board oundcara for the irrirrers..ers hero Free c. E3 POUNDERS 48 -2 6v operated reed switch relays Guaranteed 12 months_ adaptor ka a 1233 377. 1 DC sotto,. cb_bler a raw id 123 to 20. 12 to 5.23 vr 12i 49 - 10 neon rakes - make good night tights 328 1 2.e4 tire swell Sagami. rem condom G_awartl t yea 50 - 2 x 12v DC or 24V AC 4C0 relays 12 volt MOTORS BY SMITHS 393 124 S.T.rrA norm pigsty 13a sobs 51 - 1 x 12 v 2C 0 very sensitive relay Mate for use et cars. etc these are wry 3910- Mars turstomer We 2A WM 63 liar Sist nin41,4 52 - I x I2v 4C achy powerful ad easy re.erable. Sire 3 li- Incurens tuts graded king by reks- They haw a good length of 3913.1 Nose Ma to Et in eons kadd axiom: up so 25m 53 -2 mans operated reins 3 x 8 amp changeovers S. sonde- 3215. 1 vaasprocel rate ail take 7M Naar ErrafOrtrat 55 - flocking mechanism with 2 keys 1.10 to 13.46 .9'16. sire! to.. 3 Linos en Ms ask of mete so 56 - Miniature Uri:Selector with circuit for electric ignerr 3 hp L5.75 ti6 to f750 55 350 57 - 5 Dole House switches 3917.1 P.M ad SLUG 10 vana-etaxtsant tte it Ms. 391.8.1 724Sr mars uralana wet trate mod bard en sac ea, 60 .- 5 ferrite rods 4" 5/16- diameter aerials !SOUND TO LIGHT UNIT 3933 1 051 anneser 3 IS Co; de et coroner 61 -4 ferrite slab aerials with ISM wave cods 3921. 1 Coeds Lecke corm -ton codoser Ear 350ac 62 -4 291 ohm earpieces 3222. 1 203.2-zero transtormor 233 to I 15y tonadal 63 - I Mulard ThyriStra trigger module (150 phi 64 3773. Ms 0 Ms tapped 204 0.20r 103a 10 assorted knobs Y. spindles 3921 Scorn dsc for ace," -alstn 66 -5 afferent thermostats_ minty bimetal wts.1 r Eicrt. mum pliers 65 - Magnetic brake - stops rotator insrandy 67 - Low pressure 3 level switch e3 - 225 watt pots 8 ohm Conpkte ka of pots Mr a three cturect mad to rept saw connoting E4 POUNDERS 70 - 225 watt pots IOW ohm ow 3303 warn of Sawing. the this at bore d pa. antisbon 14is purr 4911.1 Car Rale acne ry rugged enough fa deco work. The wit is fors -el n an wee -.ca 4212. Sin in in co as fide fl PSI, 71 -4 wire wound pots - 18. 33. 50 and 100 ohm two tats natal case and has co -acts 10c tad. Cirarn+4_ and a mats 4913 3 Hats -an trre ard set asches tsar. p 73 -4 3 wan wee wound pots 50 ohm oirerf. The ardo npat and orban are by Si- sockets and Vac panel 3913, 1 1S W, rantlat.,-..-C we dais 3291 SeCOntary 77 - 1 time renunder a. isoitle 160 mins mosang fuse holder pram* thyrMor proetrtian. A for pis plug and 4915 T porraki mom2-.stack fated reel cestcr fed mod toter 78 socket Cocksure ease of comerting laps Speoal ace is (14.95 in to Mars optoad °lid operak ace oafs cm: ES - 1 mains Shaded pie motor It" stack - S. shah form 4211. 1 UweRcer 3 CC1.2 roe., 5)1/4 col standard axe .0.213. 1 leek meter reel deflug drub i DiCaVISORI 136 -2 5- ak fan Hades fn K" shaft 41919 1 IS, or n-oW alt 55 W sold.. 4727 87 -2 3- plastic fan blades fit3.." shaft This Month Snip 4720 I Gear min Tens lead rat-et:en 88 - Main motor suitable for above blades 9" VDU OR MONITOR deal to wok wish corpuses or yds.o 89 - 1 mains motor with gear box 1 rev per 24 hours carers tam Macs track ad who nee ref 604 Whiph ES POUNDERS 91 -2 mans motor with gear box 16 rpm ease is irreaosinn and X Ray ratiaten poroted VDU is food 93 -4 11 can moulded bases for relay; raw ad has a tine bases and EHT &oily. Requires sty a lE&e 5293 Tues2amo uoser memory 233 2A30- arra 2 133 la dc peppy to set a gong. Its made up n a tararred 'real fare secalay. 94 -5 B7G vane bases work bin has open sides so should be coed fa you ore hady 9993 tradorrer n waserpoil neap ben 241 Sa add 12 past 95 -4 skirted 89A valve bases woh a ad anal Mr sox rend make a case on of two of C. 6'i 5293 4 balk heatici *mere each 2i-yr dot coweesa heater 96 - 1 thermostat for fridge sposko cabinets/. The VDU cones complete with acid dragra, 990. leg lanoniall blower eon aro at owe ern 96- 1 rnoroised stud writch ls.h.1 5291. 14- blower. motor is =Pik ard has been bre testa ! and has our sis months asoaram. Of- 5288Xis Aldo mat debt sowed therm siva in bra for T.V. 101 - 1 216 hours delay switch fend at a of kip don scene fans are askew fa the tube alone. war darn Del 24 Cc a x 103 - 1 6. mans power supply unit ordr EIS pis 13 au_ We also have lane that Wad the trot 5F9L Garb trareci-cr It. 1., 13 de incsa tar, agan brand new but °Hoed without guannam at 03 pl.*, f3 104 - 1 435v macs power supply unit 5E95.. Verage risc :' 105 - 1 5 pin hits plug and panel socket piss_ We do a kit fee de 16.3 ia on to oposte thrs reado. UST. k7.0.07acce -; 5-8-1E0 am TOO add Prices [3 ore ref 3226_ EPA post 107 -5- speaker we rade cabinet with handle - 5293a 0-92. rand 109 - 10IG- spindle type imam. controls SLIDE SWITCHES Sub ni 'canoe sire any 15-ren 4 nen serge 9032. 04933 arrce, 110 - 10 thder type ve.`...-ens controls 5293. Marti pole Charge over or oni off Price 5 for CI ref 9D653 - 112 - 1 heating pad 21._ 59100. Nara miner tie s - 114 - 1 Ity awake 1.' 1172 LOW VOLTAGE RELAY ONIRCH4 3.54 col. pfug it dl sceAets. 53 cio 52101. Node moo. 1 ry- 0. rcksti,-. 115 - Wal ramming -coal 24v consorts. Brand row offers! at a say price 2 for El ref 13050. 118 - teak effect e.t,-_i 5" speaker cabinet POLARISED RELAY deposing soon es ibrechos do current as low E7 POUNDERS

120 - p.e.b. with 2 am.: `al wave and 17 other nos. 14 h63 makes this open acaa, so it cold be used to protect deEcam 721 1 cocoa teat sokler we - M3415 sigl rm.-rade sp and p6 Sop 122 - 10 nets twin screened flea white p.v.c- cuter wesburnents or as to earth leekaoe. or reverse voltage tro etc_ 2 for El ref 131350 132 -2 plastic boxes with winekms, ideal for interrupted ER POUNDERS beam. snitch 0E- SLOTTED OPTO SWITCH tem red emitter a -a sensor mos-tea in DM 1 Chow 42a taighx. mooing 2312242 moan 15. 155 - 3 v_ - push button tuners with knobs !!..nnisel marking, so that the antler berm wren tram makes a con 10. secondary t. 'scams switch. can be mei it dectrrac g-ition, peed sosess etc 193 - 1 c bo., sloping metal (tont. sidel6 x Manor. 912 1 6' Lederer:me Mamba satanic for a fre earns or Issga isms -_x: 4..H -in are Price 2 to El ref 8E645. aim mans ocrtami

- 893 1 241 - 1 - ,- -very Ball 619- 15 ohm made fee 24fir TIME SWITCH emu:duty made Arch hot German peciaion_ ten se* lig pswerki so deal tot own mormrser under 4" square wish 15amp clo contacts can be set an 825 1 cora,SOO Ran c+ EaCa.... ran 296 1 Pe-;re tene awed. -2 os ars Na co oxcarts 3- 3- - 243 -2 speakers 6" n 4" 15 ohm 5 watt made for -_-and 24rr dal to the nearest 15 ones also with a owuride sitt.k.ch_ 5F7.1 Skew wad inrStra rsy ke 044 826 but 1..my we hew oar 301 Sedalia:ale EFS 1 Roar tan 3h 31, 1 Sr 220. rout totted 266 -2 nuns uenadIBIles 9V ISA secondary spirt aerial+, so OK also for 115V COMPUTERS the Acorn "13ectron- as used irs romp stools for MO POUNDERS 267 - 1 main transformer 1SV IA secondary PCS games and se away jobs. Works two color or BUM ad Wine momuirg T.V. Proper price was EI93, or Prim. vested and wait. E45 10913 1 meal* freer with oohs. Karon Pasta 13 cue. resod tort sIghny faxacy CO (3 eon ani laser weed 10914 1 tare wrath 1 an off per 24o arra egad fl par 330 -2 6e -0-6v mains transformer .3A p.c.b. mounting 11:215 1 Mal dowsed rem 233 AC mars 393 -40 double pole leaf switches SW rot mating CO E3Put.as are raw and carrcact. rash mom P.S.0333 page hadboce_ TV kai, and sorter 13916 1 Cosocaki Sr nova 2 sea nor kkrems aaT Irckl. 365 - 1 7111 61304 50hr metal cased condenser ossote_ Fee range of Sabra. also a saixk at soy Sow 12218 1 mans opened tam 453.2 - 214 in_ 80thin loudspeakers 1^,219.1 124 Yarn bol rotaylocel. arts opened. r+ con ow E5 eon Prices 0921.1 toot metal box site 19- ar 7- deco lociatle El or,: 4542 - 2S1 n. Sohn' loudspeakers 102221 sensate lea rater rein 462.1 - mains operated relay with 2 sets cfo contacts TELEPHONE LEAD 3 gnus keg teem -eating ore end with raw ST. 101923 1 Ma machete heart 3 Ma wins each 141131. - 4642- packets resit fitteirsealer with cures Rot ;wag and she odor end ends 4 cv,c.9y coload coded wires to fa 14:924 1 hd Pod osier Moe sues% 2h22.4rroaras-1 4652 - 5A round 3 pin plugs wil fit item 193 to phone a ap;fance ReptanK rtla lead on ad pew* rw.gung 10225.1 103a Ado eandower 50 057.- cora 8 ohs =oda 466.4- 7 segment Led. deploys writable tor new 81 socket Pre' El red 13054 or 3 Mr12 10926_1 Srossery" Over JutorSalcs meows; said as such ref 164_ 10221 12ir ogre eosins tor 470.4 - pc boards for stripping. lots of valuable parts 10231 1 narsntreMr 00 orb east atom 12., Sr Eat Thr Sac 473.1 - 5" 4 ohrn speaker with boat in tweeter Rain -54 motel POWERFUL IONISER. Y.P31 1 drIErre worn 1St c 0 d-Sacts soy Porsches Ice tactdab - 3A double pole magnetic SO, SEra repairing Gcrwrstes aCCcur. 10 tescs ,ore IONS than and sender 101'32.1 ES .70 1:Eth to coke inerstk

fuses sec,ns. Wit ref.t, can rare, office. sl'eS .ss V.- - 1030u1 25v axial electrolytic Cdp.3C4104S /As:es vat fart Otto eel work hanks a c; L15 POUNDERS 00.=4- 2.1 to, care incicataa. EISO t 12 P&P tSPI. 1 14 fa 115w to 6 axe 1522.I kit lot par to nether. a two 11 ores TELEPHONE BITS INT I tire meth battery or rens operas - 16a c.,ra coo, socket (has surge arrestor - rexjrg condenser MC) and J N BULL ELECTRICAL 7 day poaroorsabe has 39e name B.T.pluta [3.95 DEPT. EL, 250 PORTLAND ROAD .tension socket 122 95 QS POUNDERS Dual adaptors 12 from one socket) -- HOVE. BRIGHTON, 2591 1 15:0 PSI hylazIc pre 24. do meld% mare for cortarang air Cord seminar:trig with B.T. plug 3 metres fl CO SUSSEX BN3 5QT ash ands cone* era. Kit for convening old entry terminel boa to new H.T. master MAIL ORDER TERMS: CASH. P.O_ or - _r rem order. Onas socket. complete with 4 core cable, cable airs aid 2 HT LIGHT CHASER KITwater dneal bent ArtnCrer-ran noer CO add El Novice Mope_ kfcrate, art ordens accepted de air ,and n cosecton rash 4 sets of Xmas fah males a wry extension sockets [11.50 shorts end pub& companies (min 5 &Wad alert areonding doon let fart. star Cr dos. only ES rel 11(55 160 mfrs 4 core telephone cable =mood Row flriatara f02731 73160 or 203603 EE December 1987

ELEKTOR PCBs HIGH QUALITY REPLACEMENT KITS AND COMPONENTS CASSETTE HEADS

- -- a -th We are cdferro PL -8s kits and components for the ex- ELEKTOR. Au kits feature tsghest coaEly

. - Ewa cop -actors for exact fit on the boards_ SW LINSLEY-HOOD aa0 up a raroe of carrcsarents and we offer these III = SYNCHRODYNE AM RECEIVER rats CM -5.31 of 10. co-rposenm to mount on FCC uniess othetwa,e = stated. ' - - - oa.drs _,-triagn kati.redr, WrrnawWr,: aro-wed he the Author. uses 3 clout,. OCTOBER 1987 Do vow mos Secs orbie, A worn head co.A1 be the coataiarn Fthrg one es at a stacked m.cut toe total raty. saw uS crarsaucom and SS8 .44apter PCS 87662[3.364-Trad, RP Heal 110551 (14.60 Ths enc.:safe waS boOS the AM sectors of anti., high goat or 00 reit4aoaraott heads cold tartan peace..ca better that MN' Kit87662K (2.25tow Noise Atic Amp. Standard rnoantrgs nuke foteg eaa and our ICI Test Cassette betas, '. Ala FM sntr.c.t.I bardadth we 33) saran arroafers E3.45 .Stelesall PCB rnmantredFCC 137059 sacs* and tonng Mary ccii St d weth the FM sect., set ttea..nonsoaten ihte me the 2C11.0 erattanwetcl. TM.T5 componentsexceptthe ecaEkaLeced rers:on the taarra at lomat pores for cewe Pans Consae dtWeh 450 JI.H Synchrolyne /GI Spec*a--' E65.90 Iowa -e, See our test for offers onFat 137058K1 E11.16 and see The todoneg okst of as most pewee reaa Cl are a.. - ths ,_-.--earecd=370584(2 E5.62 ta, use on Dolby michres and we es stoci AmpErear. PCB 87486 E3.76 -h kits _as the correct E96 Ft 374:39( E6.84a -to as ,-d'i(55341Cs HC20Permancry Stereo Head. Tt-s ode suMani head fated an ons.a coutenea an mat decks 13.65 HS16 Sendai Ahoy Super Head. The best head we can Ind trevae GOLD PLATED AUDIO CONNECTORS Me me, Pen--sloy, hater 0.1.4,1 than Ferhtttareetse free resorts. £14 66 Tr.:. a- _ : a and PC8 H05514 -Track Head for ...40-,e,,aw ow qtoittoçlanar ao, Full dace-. (14.193 s catch doom mol ornback head mount e,t.thi a ; -;S Ih.tjdetadson Out Ests.. SMUG Standard Mounting 2/2 Erase head. Ccenpatiok wet. above to. H1 4 Track head . 13-07 400 SERIES LINSLEY-HOOD ULTRA HIGH H524 Standard Erase Head_ Sena double gap. h5h effitisncY 12-25 F4561 Metal Tape Erase Head. Fart dada* gap ...... E7_35 QUALITY AUDIOPHILE AM/FM TUNER SYSTEM. HXICO Special Offer Stereo RIP Heads .. COillpkTs LIT with the co-nom:oh FM tuner to go HRP373 Sendai Ancry Stereo Combination Head . . C3360 v. t taat S,nalau.1,e AM rece:ver. This sat offers Me tEsceer-ng HRP373 Techrucal specification 15p entteast the char* to get the titrrate sound Guaty rosstae from HS%10 2 4 Stereo DC Erase Head [6 70 VFL600 VERTICAL FRONT LOADING both AM and FM t,..11,..2sI3,33 systmra. Thes is made a...ease br HCOSIE 4-4 Erase compatible with HOST (3972

both of w Nth use raw and novel CASSETTE MECHANISM herng conwhately Sa'." - " &curt features to ,...dro performance_ The IuT COP -4.M The tate <- -- -- htfht. the need tr, -.15.anabh Proed the urtra high col.W.:4 stem, decode from -Dectroncs from load, , .-s Ths /FM cornes with Vert'. Y R 4. mot wa.- reari r.z. ht standard mountings so mat Mei tray be Today InternatonM m Synchrodyre AM =bye, from HART TRIPLE -PURPOSE TEST e=argettSo, tenets. our raw ral hards-d rec. rand. The rne.hansm,Mro "Wireess World-. cased to rnatdt our 300 Senes ampEfiers. To CASSETTE TC1 ran a 3 dgr oowatng ken. mechankal mtoo stop and a sinegry conanucteet the F1.1 section am 3 ready bait preakened . front erd The photo socked loop desnodu4stoe1F stage having a , 4C. with ce-aral wedaer and kr. func- , ^,31a. heads Ch-ir (466 pa 2..t response down to DC and advanced senate Seat hold stereo decoder Cod alCoOt alt. - -s ran carter has a frnfrautcat4 damped 'soh together make a tooter ...Ouch stunts superb but thanks to the . . 9ms:wed md ors". needs a 12y DC suscir '. , regenous double sided FCC layr..t 15 EST, to oral and to=ey stat4e an -;^J% Gat stOS%Tn.., w4 e.uratLaOtt 71-e Synchrodyne AM section ynth -Is seectaltie barsderdth Pt -.des Tape Head De -magnetiser. Haa). sae mans ccatml tnt Pre.ehls SOS1Xin...r , - - deeo sxklang trona and keys. A roam the best postaiste reacts from tang and Med,n chmreis so Wit) up of 2.6 -ad head nagnetsatcrr caning rso-se on othhati ECM -; a a-, f loyf Caned Poe Tope fow nacc-es. sere real CIS .; 502 Velte_v oaaorg Cassette Ded 424.30 necessary at these days ol sort vans up to IIN3 full AM FM nuactel 331-01 _- _ Z.? tore ca.Xcu R.I D-ty Ent, - 1134.61 seet1 one err c-Alycc" LISTS IRCs to toter il.CGA II AV Cri,t . £147.87 A,Iwc Poor cr 5 MC, fly K4-30FV 4 TV Pr.r...me ea./ per ccwV dpraz o.r4ost 3--x/ s-S.s3,CeSt 00e045 AY 1,7.38S INLAND OVERSEAS Orders up to £10 50p Please send artfcent to cc... STUART TAPE RECORDER CIRCUITS Ord.ms £10 to (49 - El Surface ow Past as co.t, Orders oum ISO - 50 tecturra tors thra hood ITIOTSTC..39 wstmn tr, cock has arcs frtecl Stan

dad 250.0.' -r-pn and cu.: . Fua dela. S on .3 OTT into

£133 . Pert.- ';-se Arbd-as

Personal callers are always very welcome but please 24 Hour Sales LinePLEASE ADD VAT note that we are closed all day Saturday (0691) 652894 TO ALL PRICES 131-PAK BARGAINS £140 ha Orr DeflailEat F'sa, 5733 ::: 7 -: . . :" = 2 MO

E.E : e a ::::, 3Aa 12 -.. ESCO YP34 2::..: . a: _a RESISTORS. 8735 5: A ..'.:E,E.:: :7'73: good .-,-,et 11.00 171 310 Ask -red Resatas, :Taal sates and :.p:,-a'Et CO 5703 30 Assad. ia. ; a. .a -s. 1A.104. rased ran . E14.3 E2120 172 3)) CrtosPera,-.... Ni-11 wet veto -mad caned EI.[IC.)VI ct.": 87141 105,14.10254 - ,.:: - -a 7A 100r. Eratmed [1 40 [2.00 MO 5.1 era Patears. aced vales and sydes. £1.071716 52142 A 404 Pdas-c.--.i'l .41CCA 7043 3).) Fri.. (1.00 EEE Tres . . . . (2.00 50 Verrea.rd Reeser.. clay( martk takes- . 1.1 CO 87443 5 57157 145. 2: :ameba:rim 2-50A [1.00 171 40 50 Precisen Reire.t.15. tierce (1.00 57124 3 4.4 400y 7taa_.a lax 1140 MISC. 171E1 1001 red 2 Sr: 7.-:.....s. esstr-yeb.s L103 57187 10 SCR'S 83:1,14. LK-, 049C65. V3V4.... 7033 LIDO V717 50 - red mon 00

. wars _ Ft CO CAPACITORS. matsa oral corr =r-itl gam. Dcdes ...roofed £1.02 V713 3:1 : try.: 1719 .40 - riaid (1 (0 175 23311.44fr' _V' ENW-,31 ki tyott (1 0) 17155 50 0447 Fid brdel gem. thades .red. E1.0) -it- t -a- ,6922 S: _ : : [to) 1.75 103 Cot -ant Ur erred sites (IC.) (71.955) 0470,3 :.rer-.4,raer.--- Dedes (1.07 11 03 173 103 Asso-ted Poryerar Pownere Caaeceaa [TO.) 17197 50 OAK tide era- Dede. Lt-COdid DEO 2723V742 E140 2100 '.710 90 C253 Ca0.161.11. Mit fol. rued rates 117.0 17133 40 6.421351. 5odes 384 2A. fast 1=024 011 53 teatittes. al acres £1.0) 87222 20 IS 57.d 5w:tess. 511402e. Rt3te... (1.00 (P43 4 ;_ : - a- : TOSS £1 03 9744 IS at II., a 10 : £1 03 '.1112 4) Eectrdr....47:5715011. smog/1013 SIC.) TRANSISTORS. 4754 M 4.11' - 'A.3:5-TTS 4: E2_50 ..113 30 r-r -a,..tal. 150:31CO2rta, ailed so...... f 193 10) EL Tara_ /..95 dad:. Pied ai'h data EIDO E4 DO .714 5) She Area Caps. anal tate; OIL,) 2746 rise,leo 8723 TM SI. Tire- Pe ciart. co... a..r.t', &a [300 2731 1 attars & Ced CA. KS. ne do. a- E :250 . .718 23 .01 250.: lan. lens Vase Caps ...... LIDO .... _ 8747 ELK [2.35 .743)23 Tartelm Sea) Caps. sacred Ilea. (1 00 TO SE haw Tres emir 21.3355. treolai 5753 1 EeCeOlc (Arm . EN. 25VA .. . 8745 5 Pin frPfk7N7 Maze i1/4163' T,3"3- Akectl _____ (IC0 2934 1 [eat -do 9a2ff. 9e. 23804 _ . 5035 .1,1V a ;Mr "W.r. reariy,c1 . LLD) W 604 SL Serzhrg Tres_ TO -18 ed TO -92 ILO) £055 .7132 3) Uln E.-ehst:um rnel rat.....47n1.1030,4 61E, (100 5753 vria IBeartric Boot,. 13,. 23VA 1931 60 P?..7 SE 5.,:t(g Trra. 70-15 ard TO -32 11.00 5766 1 TKA'SSOT Coaorerts PatS, striord.clad (IC,) .,-,33. I'5.6 LEn Eeett4tcs 2 IDCO22:20M-re 10 16. E1_03 2750 ICO Al sots Trasers IF% MP E I CO 5757 1 letencre ode col ear 157=0ra plg . £1.25 £1 .07 (1.45 1-,Tri... 5715)23 871629$S. Tare SPY Kt 200,..A 145_240 1092 . 1733 1 Noe .n.aire rest 3.5em 77101 35 EC1713 SC Tars_ AN 435 TO7rrA Wag, /032 £1 40 1795 s-4-01.. E1.75 . - 25- 4., raxi-g PeiLs (100 1 Paso seta ase £1 07 - . ...ad rex rd ado., tED s £1 0) 17152 15 TrasKI SL Tars SPY 7.0, 4037A 1151100 1027 toFrt±sTaux.SzCi14.5,.1E,D11-rri--tv: £586 (102 1:7133 15 ressi St_ Trre MP 40, 403trA ittelC0-, TD22 . £1 .07 1 Lhvtrse Ter.. *Tr atria EE 03 27151 15 ILPSA_K St. Tres. P.5P84 MOM Sth-50- 1032 E1.00 1 Pen 8.zrar. 7a*r.ra.. 12. f 1 25 .727 ii uqa_r sad LEDS ._._.. . 11.0) 1795 1.0 PeParglar .r Pad 1.31's (1.0) 1915520 57533 SE Ttrs. M.N aza 57184 KT TOST £1 00 IPets Setate. earar.re. 243, 1'125 'if -57 15 Oat) atonal pee_ Mardi S.oes Vase £3.0) 57156 33 5741651 It -was. WA ectst 5173 1:15. TD32 (1.00 1 Cat. Anrra Seta. 2 sly £410 57.13) 6 760 7...;., OC tann- . 7.5err. PCP EhDra3 LEO Dada/ .. 12_0) 57157 15 zrxso)se,ks St. Trrs. Rt7 deed.. £10) 1 Can 4.-ze-ra Starr."... 3 lets 74.75 1:9131 4 C. -KEN 7 Sag CA .6' LDP X42.5520 LW Dagiar 112.03 57135 15 1TX107 SA Tans. :Pawn K107 p1tatc . (1.00 7 Pass Fite SICCrfttar_ cart. 10_30 (SOO 17132 E -^M (heft.. .6" 3 CA 3 . CC 5630501M Dada, . .. [2.0) 17159 13 Z1110351_ Tare ION east KIN crake__ PAS 'art,. vt.e.re bad (300 £1.00 1.7134 E: 30001. Deft* 4-- CA 7,47255301M D. E.200 57151 25 act ea a Pars 1)78 84 2COtsS TI92 = .T r-reciam Var. Eat-. 4 o5t.ano El 85 1:5138 .:.:Asso-41 LED Dockers. Da am wen dais (SOD 27152 3 5.55451 SI P.m. Trrs hP2i Ma tA Ke20- (1_00 'ttrtr_re Turseitur Bety7ere 7.50 44141 ';:- :-Er; Coxed Volta 10.60 47163 2 ....7:. ESP daiS S1 Peas! Ttrs lit S.E515I... (TOO ; 334 Lin cub tan Pcrs, dee %ou cap tres El .03 WIK. 4. .L- .: -r LM Degas./ CA 11.00 0154 425525351 7:-..ele Ttms ?Pt 40, 40,. 7A Wt3)- (1.03 a '4E Arared Pots to and saeshel boas ft 00 77723r.77723 - ',',N I.- t.-r)t LED's. %had od'o... EI CO ...ples 6 57TM IsTli SI T,3-1. K., SA Kt5020) 1039 ITO) - 7-He.t. tar:arse rd retce. mud vales Etc.) 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Send your orders to Dept. EK, Ell.PAK PO BOX 6 WARE, HERTS Use your crerit card Ring us on 0763 48851 NOW and get your order even faster. Goods TERMS CASH WITH ORDER. SAME DAY normally sent 2nd Class Mai. DESPATCH. ACCESS, BARCLAYCARD ALSO ACCEPTED. Remember you must add VAT 01 15% to your TEL 0763-48851. GIRO 386 7006. ADD 15% VAT AND order. Total Postage add E1.50 per Total E1.50 PER ORDER POSTAGE AND PACKING. order. EE 78 December 1987 classified ads advertisers' index Bi-Pak Semiconductors 77 CONDITIONS OF ACCEPTANCE OF J & N Bull Electrical 76 CLASSIFIED ADVERTISEMENTS Cirkit Distribution 9 Advertisements are accepted subject to the condi- 12 tions appearing on our current rate card and on the Crestbeam express understanding that the Advertiser war- Cricklewood Electronics 8 rants that the advertisement does not contravene CSI Electronics 78 any Act of Parliament nor is it an infringement of Display Electronics 79 the British Code of Advertising Practice. The Publishers reserve the right to refuse or with- Eltrak Electronics 12 draw any advertisement. Fuselodge 11 Although every care is taken, the Publishers shall not be liable for clerical or printer's errors or their Grandata 78 consequences. Greenweld Electronics 9 The Advertiser's full name and address must ac- Hart Electronic Kits 77 company each advertisement submitted. The pre- 78 paid rateforClassified Advertisementsis 45 Jasp International pence per word (minimum 12 words). Sernidisplay THE Jaytee Electronic Services 4 setting £10.00 per single column centimetre (mi- Maplin Electronic Supplies 80 nimum 2.5 crns). Please add 15..,. VAT to total. All ELEKTOR Matrix Systems 10 cheques, postal orders, etc.. to he made payable Microkit 74 to ELEKTOR ELECTRONICS. Treasury notes should always be sent by registered post. Adverti- ELECTRONICS Sage Audio 74 sements, together with remittance. should be sent Sherwood Data Systems 4 to: ELEKTOR ELECTRONICS Classified Ad- Stewart of Reading 10 vertisements Dept. 1 Harlequin Avenue BINDER Technomatic 2& 5 Great West Road BRENTFORD TW8 9EW 10 England This cassette style binder villI help to TK Electronics keep your copies of Elektor Electronics Universal Semiconductor Devices ...12 NEW clean and in order, even though you Watford Electronics 6& 7 ZERO INSERTION FORCE referto them time and time again. Xen Electronics 8 CONNECTORS Because no wires or fastenings are Zenith Electronics New design -High quality Low cost -Tin or used copies can be easily removed and Gold plate 24,28,40 -way e.g. 24T:£4.75. Audible + Visual continuity tester, probe replaced and each cassette will hold one year's volume ofElektorElec- current 0.1ma 50gm, incl batteries. £9.85. DELUXE WALKIE TALKIES 49MHZ, LONG P&P £1.00. Other items, SAE for list to tronics. RANGE SATISFACTION OR REFUND. £24.99/ JASP INTERNATIONAL 14 Tudor Close, Price: £2.95 - P&P PAIR (NORMALLY £31.49). SEND £3 NOW. Wokingham, Berks RG11 2LK. PAY BALANCE UPON RECEIPT. 48HRS Tel. 0734 782084 (TLX: 849021g) (See READERS SERVICES) Please use the Order Form in this issue. DELIVERY. XENON (Dept ELE11), 24 WHARN- Trade enquiries welcome. CLIFFE STREET, BARNSLEY, YORKSHIRE.

laa::::all*77 13p741527 1597415132 50p 15540 333p745133 212p VOLTAGE ... 728 13p 741.5223' 15p7415153 51p5932A 4009745267 7439 REGULATORS ,_ ,...51 13p74153) 15p7415194 53p .Cr" 933p74557 4509....,. MO 17- .4i:. 13p7415M 17p74151% upatm 57097,48:88 'WO502 3Sp ,:.-.6 36;4X5 40p741533 17p74154% 62p6.5.2) 17139 aVV 1919 1:07 13p1086 32p74531 16p7415157 52pfez., 330p 2:01, 7.,-.T7L5 23,rr3''' ry 4:03 38p44e3 9397415313 17p7415721 56p653) 10669 -..- 75118 829'-'1 3o 4773 70114663 1E9744540 lip7415210 559 ..?2 1.60p Vp .015 4094 me3 110P73:6 alp 4Sp741542 339711.5241 SSP5545 ESOP .71.0- . 731> 149 4311 EOP 13p 58p74154756p7415242 55pV51 630975,,2 le,7515 4.1p 4012 13p9333 93p 741548 56P741--U 130111 fa70 210PIsm X6p7375 52 4013 19p4499 46p741551 lip7415244 50p 6.8 220pri,,, ix,2920 03p *74 35p4911 30p741554 1E97418745 50pfiazet 900p75//5 /339TAM 21T. 1015 Sap4.7,1,2 29p74155517p7415247 50p650 3 500p ,-5 ,21 us,7112 Mp Advertisementsare expected to conform to rules and standards 4316 18p1513 32p741S73 28p14143 50p ..9 ECOp75127 1E9 7% , V> Mp laid down by the Advertising Standards Authority. Most do. 4317 alpzeal 55p74157422p7415219 92peats 199p75,w npp z 21`P ra 4075 33045,6 2COP 74I.57529p7415251 339We 333p515: 116p'4-' ZEp The few that don't we'd like you to write inabout. 113p 4)19 2E945.:6 60p741,576 28p741553 50p "-.3 140p5155 upp ii.,-' 4333 Mp4507 33074157623p711.5256 60p6271 140p75159 203p , 60 And if you'd like a copy of these rules for press. poster and 1V1 36p49)e 70p741.553 43p7415257 42p6212 3159 T5760 4009 14 cinema advertisements, please send for our booklet_ It's free. ....n2 3594510 37p74158545974157.5 47.p6.6/5 620p75161 400p..,1,, ..C.C9 .A323 13p4511 40p741596309741523 58pSVC 110p757E1 7COP L';...... "' 1,,,S9 -4-4 25p4512 42p741533329 7415206 33p8.3KA 4009 T87...72 73:9...,_ :..717:. 220.--". -1,_.:5 i3p4513 83p 741.591 759 7415265 SipE2654 3304.75.,,,_,'' :..72:04.577 iiri; The Advertising Standards Authority. .1L.:5 60p4514 7Sp7415W 33p7415273 52p3155 350p..,. 'eop."... ,,,,,,, 4,,,p 17C7 .615 7Sp741.5M 30p7415279 40p8155 350p 781.3s' lip -51a 204,LM723 149 L.: 40p 140p Zip.616 7415% 47p7415233 8165% 123p '7,5,. ,,,c- We're here to put it rightif 39p4517 120p741S%60p 60p 7415253 811596 1309 /309734:5AC acco 17p4619 19p 7415293 33p811597 1309 2*112.(c - 7415107 32p ,....,,: uop 1039 93p3519 33p 7415169 34p2415250 30p5115% 1331/ - 65,710,1C 1Vp ASA Ltd . Dept Y. Brook House.Torrington Place. London \VC I E 7 H', 54p 45.33 35p7115112 36p741.V65 Ylp8224 270p i.r...... rzC.I0C 2159 60p4521 90p7415113 32p745366 37p126 270p7s...w Sep73.* ..0 C 3X9 5225 :.., 30p4522 SOp7415114 35p71E5357 3543 270p-z-,.tsi xisc, 4594926 40p7415122 03p745333 3E9820 E09 44MUM= 425 1E0p1527 44p7415123 Up 7115373 Sip525) 85097x53 659 EZi ccR.t.'":7 47.13 75p4528 40p7415124 Sep7-'15374 Sep 8:67 "CI:4'P7557 ... !..._. 2.7 701. -Es 45'35 4.8p46:5 7Sp7415115 35p7415375 SipV51 333pr 433 y.,.; 4:23 130p451 52p741512636p74!R451 5098753 320pr61 66P67.. F..% 7r. 4..10 36p4551 83p7415132 40p7115353 45p5255 310prsraz 12 47.1 33p.1.3 190p7415133 34p7115333 8:9K.4 1200P 3T:,5 A:42 30948-6 29p711.5135 Xp7115629 10E95257 350p5122 CSI ELECTRONICS ..,....".:.f.11111.111 A:43 35p1V6 38p7415138 35p711554/ 110pETV 3609an, ---,...., FED 3,6 "636: specializes in KITS a officuit to ontain 1:4-4 38p4557 190p7415133 35p7415542 200pV71 3403p575-*. ,,TZ110 3., ta 1:7 COMPONENTS for the major projects in

,...:8 7754553 60p7415145 83p7415644 733095272 1200p37* 7....7"7 2.M 3-, Gr4'.1,7v Elektor Elecuonics. , 41 4594554 33p7415147120p7415515170p 7) ASC9877" ''''''LE0 5-t^ ma 5; 1A 459 4425. 42p7/15148 543p7415E70 72p5353 330p31-33 1863450 5'- la es Introductory offer: Computerscope (complete kit) ... £165 A.-1.: 279 7415151 Vp745674 4009E7E3 400p 1. 5-.- CV. 93; .1- 18p 7451V 4119745E57 270pVE4 4409 KPIO1A UMC3561 TEA2025 X 9.216 M 6227 Pt E. -SE P...19.6 US FOR 119£ xo, TDA1540P X 11.592 7.1 4.i. 209.41503 1597415154909 ARE UVC3101 8052AH-BASIC ,.. COMPUTER LLSTED KRE AS V.2 32p 7.11_58115p71159.5 41p 8ZSEI ESOP440113900 350 ants 4,3i0 01-`0 IMS1455-20 781U10 10.172268 P1011 3462- 37p741553 15p7415153 47p IC 5 5738 1103pTAI3OUS ARE GIVE% 108 totAtli HPF511 BUZIO'11:71 51-110.693 HEF4754 2663 37p741503 15p7415157 33p 57% 14C0p euxxi 116.5 8YV79-50 4:51 53p741504 15p7415158 33p2114 2049593 1015 290917.7 1grf. 73. P6? 4ZI %.V -:t: LT0321-601 135170.250 U20668 10K1 7T15 8F982 TLC272 47352P741$06 15p7415160 48p:532 32/19515-3603 5709.x944.1 0.94991spap,1,. TDA5660P 4:55 529711933 1Sp7115161 SOp2716 203p5P005641 -1503p199. 9.984n. prows '1u.7 as,' Many more kits & parts avallable For price list & ordering 529) 4C97.11.54 15p7115152 4E0'733 290923)ACP1J loopfc, de+.4.,v1.1 bravow. C.-9, info send SAE and 1IFIC (returned with order) to 4363 52p74510 159 7-4151 46927-24 300pMEMEL/ 500p=, .12341,3 r_'"' 4-' 4a.36 701, 741511 15p141.5164 43p4164 240p283407.1.A650p'."" CSI Electronics, P.O. Box 22089, 4:67 tato.41512 150741525~ 66927C44 550p2335910 2309 zwer-4, 4939 GRANDATA LTD 6360 AB Nuth, The Netherlands 4'3% 139711513 22p71151E6 74p77128 250p 9 THE BROADWAY. 430 13p741514 33p741.5166 929.2725345 4C092335CIC 2509PREST074 ROAD. WEMBLEY. 4370 13p711515 15p741511) 65p 41216 153:00Zzoectc 4E0p MIDDLESEX. ENGLAND 1071 13p711520 1Sp7415173 809':50385'.1300pMASICI 6609 TeLephone 01 904 2093 4272 13974521 15p7415174 35194,15 7SpMA5L0 ' layEr 504-1115.6 1373 1341 741522 15p7415775 429 416' 1169'----A5''-'1 ?CCP Telex MA 932 ass isunmit) 437, 13p74524 35p7115119 4594.7'6 11002__1 79107 MP . .... ',.." KSb Har1tr, Card 4.88,..psed

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.. 40MPUTER WAREHOUSEFOR CALLS THEALLADINS CAVE OF COMPUTER AND ELECTRONIC EQUIPMENT 14.- HOT LINE DATA SASE DON'T MISS THE CPM Deal *DUMP OF the CENTURY The ORIGINAL FREE OF CHARGE dial up data TheTABULOU CPM TATUNG PC2000 base. Buy, browse or place YOUR OWN AD for goods or services to selL 1000's of stock items, Professional Business System spares and one off bargains Updated daily. A canceled export order -and months ce negotiation enables us to offer this profess =- ON LINE NOW. CCITT, 8 bit word, no parity. PC, CPM system. recently on sale at OVER £1400. at a SCOOP pricejust over the w s 7:' For 300 baud modems call 01-679 1888 IV the two internal desk drives,' Or less than the price of a dumb termiriar Not a toy, the BIG BROTHER of the EINSTIEN computer, the DUAL PROCESSOR For 1200-75 baud modems call 01-679 6183 PC2000 comprises a modern stylish three piece system with ALL the necessities for the SMALL BUSINESS, INDUSTRIAL. EDUCATIONAL or HOBBYIST USER Used with r2o4n to; ttom itsmcom liFRoBr the THOUSANDS of proven, tested and available CPM software packages such as Yont; aSUeir," WORDSTAR. FAST, DBASE2 etc the PC2000 specification, at our prices. CANNOT BE BEATEN FREE HIGH QUALITY * COLOUR TV SET The fabulous TELEBOX, an INVALUABLE MUST for the coiner of = The central piccessorplmth contains the 64K, ZEIOA processor. DUALTEAC 55F 51/4 ANY video mortitorwith a composite input colour or monochrome Double sided 40/80 track disk drives (1Mb per drivel. PSU, 4K of memory mapped screen FtAM, disk controller, RS232, Made by a major UK Co as a TOP QUALITY, stand alone UHF CENTRONICS and system expansion ports and if that's not enough a ready to plug into STANDARD 8' DRIVE port for upto FOUR tuner and costing OVER £75 to manufacture, this opportunity to 8' desk drives either in double density or IBM format The ultra slim 92 key, detachable keyboardjeatures 32 user definable keys give your monitor a DUAL FUNCTION must not be missed! The numeric keypad and text editing keys even its oval integral microprocessor which agrees the main 7,30A to devote AU. its time to TELEBOX consists of a compact stylish two tone charcoal, USER programs efimi natinglost charactef problems found on other machines. The attractive, detachable 12e =niter combines mouldedcase containing ALL electronics tuner: er supply etc a green anti -glare etched screen, with full swivel and tilt movement for maximum user comfort. Supplied BRAND NEW with CPM to simply plug in and convert your previously dedicated computer 2.2. user manuals and full 90 day guarantee. Full data sheet and info on request monitor into a HIGH QUALITY COLOUR' TV SET, giving a real PC2000 WorderOcessor System benefit to ALL the ferrule! Don't worry if your monitor eneerit have PC2000 System PC2000 Business System with CPM with CPM and TEC FP25 daisywheel sound -THE TELEBOX even has an integrate watt audio amplifier with CPM Etc and 'Ready to Run FAST Sales and printer fordriving an external speaker, PLUS an auxieary output or superb COST OVER £1400 Purchase ledger, supports up to quality television sound via your headphones or HI Fl system etc 9000 Accounts, VAT etc. £799 Other features include: Compact dimensions of only 15.75" w x 1401111 COST OVER £1700 NOW only 7.5' d x 3.5" h latest technology. BRITISH manufacture fully - e399 tuneable7 channel push button tuner. Auto AGC circuit SAW later, LED status indicator fully isolated 240v AC power supply for total NOW only £499 safety. Mains ON -OFF switch etc Many other uses Carnage 8 Insurance £12.00 MODEMS LIMITED QUANTITY- DON'T MISS THIS OFFER!! SURPLUS SPECIALS OM Join the communications revolution with our super ONLY £29.95 OR £24.95 if purchased with ANY of our range of DATA MODEMS. prices and specifications PRESTEL - VIEWDATA - TELEX to suit all applications and budgets video monitors Supplied BRAND NEW with full instructions and 2 YEAR BRAND NEW State of the art products. warranty. Post and packing E3.50 'When used with colour crt PLESSEY VUTEL, ultra compact unit. slightly larger DACOM 051.2123 Multi standard 300-300, 1200-75 than a telephone features A STANDARD DTMF Auto answer etc £268.00 TELEPHONE (tone dial with 5' CRT monitor and DACOM DSL2123A0 Auto dial smart modem with COLOUR & MONOCHROME integral modem etc for direct connection to PRESTEL multi standard AUTO SPEED detect and data buffer VIEWDATA etc Designed to sell to the EXECUTIVE at with flaw control etc £365.00 MONITOR SPECIALS over £6001 Our pace BRAND NEW AND BOXED at DACOM 051.2123GT The CREAM of the intelligent only £99.00 modemsauto dialautocall index,buffer 'SYSTEM ALPHA' 14 COLOUR MULTI INPUT MONITOR DECCAFAX VP1 complete Professional PRESTEL £498.00 Made by the famous REDIFFUSION Co. for their own professional computer s5yys5tem in sfunline desk top unit containing Modem etc etc seetem this monitor has all the features to suit your immediate and future Steebeck S81212 V22 1200 baud FULL DUPLEX Numeric keypad CPU. PSU etc Connects direct to sync Or async optional auto dial £465.00 requirements Two video inputs RGB and PAL Composite Viden allow directstandard ROB colour monitor. Many other features TRANSDATA 307A Acoustic coupler 300 baud tun connection to BBCJIBM and most other makes of micro were...eters or VCR's include: Printer output Full keyboard input, Cassette £49.00 including our very own TELEBOX An internal speaker and a e amp may be port etc BRAND NEW AIM DATA. A FRACTION OF duplex. originate only. RS232 interface-1111-11111- connected to computer or VCR for superior sound quality. Ma-ateer featuresCOST only £55.00 Separate Ex BRITISH 'TELECOM full spec. CCITT, Matching BBC case colour. on frc- ALPHATANTEL. Very compact unit with integral FULL bargain offers Sold TESTED with data.Wwitere= Contrast and Brightness - even in RGB mode Separate 'S.: - -d audioALPHA NUMERIC keyboard Just add a domestic TV arty MICRO oesystem with RS232 interface controls for Composite Video input, 8NC plug for composte 'it way 'Er receiver arid you have a superb PRESTEL system and plug for RGB input modular construction etcetc MODEM 13A 300 baud unit only 2' high fits under via PRESTEL the cheapest TELEX service to be pane CALL mode OraY This Must Be ONE OF THE YEAR'S BEST BUYS. PC USER found! Many features CENTRONICS Printer output MODEM 201. 75-1200 baud Compact unit for use Supplied BRAND NEW and BOXED. complete with DATA and 90 day Memory dialling etc Supplied complete with data and guarantee ONLY £149.00 as above OR IBM PC Version £165.00 as subscriber end to PRESTELTELECOM GOLD, DIY mod for RGB or Composite video outputs AS MICRONET etc £39.95+p75£6..°5°0 - 15 Day '17 ski £1.00. BNC ski 75p BBC interface cable £5.50 NEW only £125.00 MODEM 20-2 1200-75 baud Same as 20-1 but for DECCA 80 16' COLOUR monitor. RGB input Post and packing on all PRESTEL units £8.50 computer end £65.00 +pp £650 Little or hardly used manufacturer's surplus enables us to otter this special DATEL2412_ Made by SE Labs for BT this two pail convened DECCA RGB Colour Video IV Monitor at a super low price of only EX -STOCK INTEGRATED CIRCUITS unit is for synchronous data finks at 1200 or 2400 £99.00, a price for a colour monitor as yet unheard of! Our own interface, 4164 200 ns D RAMS 9 for £11 4116 ns baud using 2780/3780 protocol etc Many features safety modification and special 16- high definition PtL tube coupled with the include 2 or 4 wire working see test auto answer etc DECCA 80 series TV chassis give 80 column definition and quality found only £1.50 2112 Eiaoo 2114 £250 2102 £2.00 COST OVER £800. Our price ONLY £199 +pp E8.00 on monitors costing 3 TIMES OUR PRICE The quality for the price has to be 6116 £250 EPROMS 2716 £4.50 2732 £3.00 DATEL 4800, RACAL MPS4800 baud modem. EX seen to be believed! Supplied complete and ready to plug direct to a BBC2764 £4.95 27128 £5.50 6800 £2.50 6821 £1 BT good working order, ONLY £295.00 +pp £8.00 MICRO computer or any other system with a TTL RGB output Other features 68A09 £8 6BB09 £10 - 8085A £5.50 8086 £15 are internal speaker, modular construction, auto degaussing ciradd. attractive 8088 £8 NEC765 £8 WD2793 £28 8202A SPECIAL OFFER TEAK CASE. compact dimensions only 52cm W x H a 24 D. 90 day£22 8251 £7 8748 £15 ZEIDA DART £5.50 MODEM TG2393. Ex BT. up to 1200 baud full guarantee Although used units are supplied in EXCELLENT condition. duplex 4 wire or half duplex over 2 wire line ONLY ZBOA CPU £2.00. Thousands of IC's EX STOCK £85.00 PER PAIR +pp £10.00 ONLY £99.00 + Carriage. send SAE for fist_ DECCA 80, 16' COLOUR monitor. Composite video input Same as above For more information contact our Sales Office. model but fitted with Composite Video input and audio amp for COMPUTER, VCR or AUDIO VISUAL use ONLY £99.00 + Carr. DISK DRIVES MATRIXPRI TERS REDIFFUSION MARK 3, 20' COLOUR monitor. Feted with standard 75 ohm SPECIAL BULK PURCHASE of these compact high to video input and sound amp This large screen colour di-9May is idealJapanese 5Ie" hall height. 80 track double stled disk speed matrix printers Built in Japan for the Hazeltine drives by TEAC. CANON. TOSHIBA etc Corporation this unit features clual.ty construction F oeSCHOOLS SHOPDS, DISCOS CLUBS and other AUDIO VISUAL arePli- Sold as NEW with 90 day guarantee ONLY £85.00 giving 100cps bidirectional, drvcsallo cations Supplied in AS NEW or little used condition ONLY £145.(X1 + Cart TEC F8 503 Double sided HH 40 TRK NEW £75.00 graphics, 6 type fonts. up to -isheetor BUDGET RANGE EX EQUIPMENT MONOCHROME video monitors. SUGART SA400 SS FH 35 TRK £55.00 tractor paper handling. RS232 c- ,c!:TRONICS All units are fully cased and set for 240v standard working with composite video SIEMENS Fool 00 SS FH 40 TRK £65.00 parallel interface. Many other feat -:e s BRAND NEW inputs Units are pre tested and set up for up to 80 column use Even when carriage on 5Ye" drives £5.50 and BOXED. COST £420. Our price Only £199.00 MINOR screen burns exist - normal data displays are unaffected 30 day Brand NEW metal 511." DISK CASES with internal PSU. guarantee DSKC1 fort HH or 1 FH drive £29.95 +pp £400 12" KGM 320-1 9/W bandwidth input will display up to 132 ic 25 tines E32.95 DSKC 2 for 1 HH drive £22.95 +pp £3.50 12- GREEN SCREEN version of KGM 320-1. Only £39.95 DKSC 3 As DSKI LESS PSU £12.95 +pp £2.50ErtETZErM5111:03Dry Fit MAINTENANCE FREE by Sorinenschein 9' KGM 324 GREEN SCREEN fully cased very compact unit Only E49.00 DSKC 4 As DSK2 LESS PSU £10.95 +pp £2.00 & Yuasa Carriage and insurance on all monitors £10.00 8" IBM format TESTED EX EQUIPMENT. £13.95 SHUGART800/801 SS £175.00 +pp £8.50 A300 07191315 12v 3Ah NEW SHUGART 851 DS £250.00 +pp E8.50 A300 07191372 6v 3Ah NEW E9.95 1WINSHUGARTE151's2 Mb total capacity insmart case A300 07191202 6.0-6v 1.8Ah TESTED Ex 1,151101714:711L114711t0ILIFI Equip £5.99 GOULD OFee3 enclosed. compact switch mode supply with DC regulated outputs compete with PSU etc £595.00 0.1a and - 23v Z.0.02a. Din 18 -11 cm. MITSUBISHI M2894-63 8- DS 1 Mb equiv. to SHUGAFT1 5v I5.5.a. SA850 R. BRAND NEW at £275.00 +pp E8.50 -.: or 240v input BRAND NEW CALL OUR SALES OFFICE DYSAN 8 - Alignment disk £29.00 + pp £1.00 VDU TE r MINALS GOULD G6 -40A 5v 40 amp switch mode supply NEW £130.00 Various disk drive PSlf s Ex Stock SEE PSU section. Standard VDU data entry terminals ACDC linear PSU for DISK drive and SYSTEM appricatiOnS. Comtructed on a rug- HARD DISK DRIVES at give away prices!! ned ALLOY chs.- - continuously supply fully regulated DC outputs of5v - DRE/ DIABLO Series 30 2_5 Mb front load £525.00 CIUME 13VT108. Current product_ state of the art 3 amps and v24v 5 amps. Short circuit and overvoltage pro. Exchangeable version £295.00. ME3029 PSU £95.00 terminal with detachable keyboard. 12" Green screen. tested. 100 or :4 input_ Dim 28 125 . 7 an NEW £49.94 DIABLO 44/DRE4000A, B 5+5 Mb from £750.00 2 page RAM. TVI 925, Hazeltine. ADMSA emulations, Carriage on all PSU's (3.00 CDC HAWK 5+5 Mb £795.00. CDC9762 80 fitioRM03software setup. 25 x 80. Clock. Swivel and tat base. etc £2500.00. Printer port Function keys etc BRAND NEW and PERTEC D3422 5+5 Mb £495.00 BOXED AT ALMOST HALF PRICE Only £425.00 C441111:1111 Manufactures BRAND NEW surplusRODIME 51/4- Winchesters ex -stock from £150 CALL AJ51O - EX RENTAL, Z80 controlled. 15green DEC LA34 Uncorked keyboard with 67 quality gold plated switches on X -YClearance items- Sold as seen- No guarantee screen 24 a 80 display, graphics cursor addreing. matrix- ideal micro corrvetsions etc £24.95 ICL 2314 BRAND NEW lee Mb Removable pack hardprinter port etc Very good condition TESTED complete disk drive. coat over £2000 with data ONLY £99.00with manual only £225.00 AMKEY MPNK-114 Superb word processor chassis keyboard on single PCB 11'w screen with 116 keys Many features such as On board Micro. Single 5v rail full ASCII BASF 6172 0 23Mb Winchesters £199.00ADDS 520 - Dumb terminal, used 12 coded character set with 31 function keys numeric keypad cursor pad Unless stated all drives are refurbished with 90 clay RS232 interface and printer port TESTED. and 9600 baud SERIAL TTL ASCII OUTPUPI Less than halt once guarantee Many other drives and spares in stock- mil ONLY £125.00. Carnage on terminals £10_00 Only £89.00 with data Carriage on Keyboards £3.50 sales office for details 100's of other terminals in stock, CALL for more details. All prices quoted are for U K Mainland paid cash with order in Pounds Sterling PLUS VAT_ Minimum order vaiuef2.00.

MO Minimum Credi t Card order£ 0.00.Minimum BONA FIDE accou nt orders from Govern me nt Depts. Sch ools. Universities and established companiesE20.00. Where post and packing not indicated please ADD £1.00 + VAT. Warehouse open Mon -Fri 930-5.30. Sat 10.30-5.30. We reserve the right to change prices and specifications without notice. Trade, Bulk and Export r r32 Biggin Way, Upper Norwood, London SE19 3XF CLLL I ic Lii W-11-Telephone 01-679 4414 Telex 894502 Data 01-679 1888 1988 BUYER'S GUIDE TO ELECTRONIC COMPONENTS

NOW302SHOPVISITTel: GLOUCESTER OPEN (0272)IN OUR BRISTOL AT NEW232014 ROAD