December 1992 - Silicon Chip Online

Outer Front Cover
Feature: The Silicon Chip 5th Birthday Sweepstakes
Contents
Publisher's Letter: Celebrating five years of Silicon Chip
Feature: Ten Years Of The Compact Disc by Silicon Chip
Project: Diesel Sound Simulator For Model Railroads by Darren Yates
Project: An Easy-To-Build UHF Remote Switch by Greg Swain
Feature: Computer Bits by Darren Yates
Feature: Remote Control by Bob Young
Project: Build The Number Cruncher by Greig Sheridan
Project: The M.A.L. 4.03 Microcontroller Board; Pt.2 by Barry Rozema
Feature: High Voltage Probes: Beware The Dangers by S.A Blashki & R. N. Clark
Project: A 2kW 24VDC To 240VAC Sinewave Inverter; Pt.3 by John Clarke
Vintage Radio: Preventing trouble & making odd repairs by John Hill
Serviceman's Log: A dogged approach is justified by The TV Serviceman
Feature: Index to Volume 5, Jan. 92 - Dec. 92
Market Centre
Advertising Index

This is only a preview of the December 1992 issue of Silicon Chip.

You can view 54 of the 104 pages in the full issue, including the advertisments.

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Upgrade Your Computer To A 386DX PROJECTS BUILD A UHF REMOTE SWITCH Controls your house or car alarm or use it to switch other appliances DIESEL SOUND SIMULATOR It fits inside the loco for added realism BUILD THE NUMBER CRUNCHER It chooses a number; you guess what it is REGISTERED BY AUSTRALIA POST. PUBLICATION NO. NBP9047 /IAPPY srH 9J-ffl'Dl\'I YOU COULD WIN "'~"'-~ \ \. \ \ \ ......... ' ' \ ' \ \ \ \ ' ""-' "" ~ \. \ \ " ....................... \ THE GRAND PRIZE IS ONE FORD ESTIVA3 DOOR SEDAN VALUED AT $15,2 INCLUDING ON-ROAD COSTS. ~ ~ " 0 -- . RIDGES ~ ~ HAM M PACKAGES · ... lately? ~ · ---- MICAMPLIFIEA-ONE AJ,'JBOnJ,) AV-COMM A SATELLITE DISH AND TWO RECEIVER SYSTEMS OUND PROCESSOR VIDEO/AUDIO SURROUNDL~FIER 120W STERO POWPEWRl~~~AGNETIC PHONO OR STEREO PRE-AM 15 TEMPERATURE CONTROLLED SOLDERING STATIONS uamo ONE PAIR OF JAMO LOUDSPEAKERS ONE PAIR OF PEERLESS PSK/60/2 LOUDSPEAKER KITS ONE PAIR OF DYNAUDIO IMAGE 5 LOUDSPEAKERS ' ~m,~ THREE ELECTRONIC SE~~~E SYSTEMS R HOME PHI THREE PHILIPS/FLUKE 50 SCOPEMETERS PROUDLY SPONSORED BY Have you driven a Ford . .. lately? . ''ilt ~JJBOJJJC} ij PHILIPS A-ONE Vol.5, No.12; December 1992. FEATURES . . ADD REALISM to your model railroad layout with this diesel sound simulator. It fits right inside the locomotive & the sound rises & falls in response to the throttle setting. Details page 12. 1 The Silicon Chip 5th Birthday Sweepstakes Enter & you could win a car - lots of other prizes as well 8 Ten Years Of The Compact Disc A look back at an all-conquering product 64 High Voltage Probes: Beware The Dangers Coronial report of a fatal accident 100 Index To Volume 5, Jan.92 - Dec.92 All the year's projects & features - PROJEC'ES 12 Diesel Sound Simulator For Model Railroads by Darren Yates It fits inside the loco for added realism THIS UHF REMOTE SWITCH uses a ready-made receiver front end to eliminate alignment hassles. You can use it to switch your house or car alann on & off, or to control lights & other appliances. Turn to page 22. 22 An Easy-To-Build UHF Remote Switch by Greg Swain Factory made receiver front-end eliminates· alignment hassles 44 Build The Number Cruncher by Greig Sheridan It chooses a number; you guess what it is 58 The MAL-4 Microcontroller Board, Pt.2 by Barry Rozema The complete circuit diagram & how it works 66 A 2kW 24VDC To 240VAC Sinewave Inverter, Pt.3 by John Clarke The sinewave generator & the H-pack output drive circuit 28 Computer Bits by Darren Yates Upgrading an AT computer to a 40MHz 386DX motherboard 40 Remote Control by Bob Young Building & using the low-cost speed controller, Pt.2 ARE YOU RUNNING Windows on an old 286 machine? If so, now's the time to put some zip back into your computing by fitting a 386 motherboard & a larger hard disc drive. Our article on page 28 shows what's involved. 74 Vintage Radio by John Hill Preventing trouble & making odd repairs 84 Serviceman's Log, by the TV Serviceman A dogged approach is justified _ . DEPARTMENTS ~- . : _ : . ~ 4 Publisher's Letter 98 Ask Silicon Chip 6 Mailbag 34 Circuit Notebook 57 Order Form 93 Product Showcase 99 Notes & Errata 102 Market Centre 104 Advertising Index OUR NEW SPEED controller for electric models is really compact since it uses mainly surface · mount components. All you have to do is install the FETs & the servo input lead. See page 40. DECEMBER 1992 3 Publisher & Editor-in-Chief Leo Simpson, B.Bus. Editor Greg Swain, B.Sc.(Hons.) PUBLISHER'S LEITER Technical Staff John Clarke, B.E.(Elec.) Robert Flynn Darren Yates, B.Sc. Reader Services Ann Jenkinson Sharon Macdonald Sales & Marketing Mgr. Sharon Lightner Phone (02) 979 5644 Mobile phone (018) 28 5532 Regular Contributors Brendan Akhurst Garry Cratt, VK2YBX Marque Crozman John Hill Jim Lawler, MTETIA Bryan Maher, M.E., B.Sc. Jim Yalden, VK2YGY Bob Young Photography Stuart Bryce Editorial Advisory Panel Philip Watson, MIREE, VK2ZPW Norman Marks Steve Payor, B.Sc., B.E. SILICON CHIP is published 12 times a year by Silicon Chip Publications Pty Ltd. A.C.N. 003 205 490. All material copyright©. No part of this publication may be reproduced without the written consent of the publisher. Printing: Magazine Printers Pty Ltd, Alexandria, NSW; Macquarie Print, Dubbo, NSW. Distribution: Network Distribution Company. Subscription rates: $42 per year in Australia. For overseas rates, see the subscription page in this issue. Liability: Devices or circuits described in SILICON CHIP may be covered by patents. SILICON CHIP disclaims any liability for the infringement of such patents by the manufacturing or selling of any such equipment. Editorial & advertising offices: Unit 1a/77-79 Bassett Street, Mona Vale, NSW 2103. Postal address: PO Box 139, Collaroy Beach, NSW 2097. Phone (02) 979 5644. Fax (02) 979 6503. ISSN 1030-2662 4 SILICON CHIP Celebrating five years of SILICON CHIP It may be hard to believe but SILICON CHIP is now five years old. It has been a very busy but exciting five years for us and having reached this landmark, we are planning for continued growth into the 1990s. Looking back over the last five years, it is hard to credit the pace of technological change we have seen. While there may not _have been radical changes in electronic components or in consumer electronics, the changes to computer technology have been rapid indeed. Our method of preparing and laying out the magazine has changed quite a lot too. When we started SILICON CHIP, we were preparing all editorial copy on IBM XT compatible machines, embedding the typesetting commands in the text and sending it by modem to the typesetter. Following that, the pages were made up in the conventional cut-andpaste method. Then during the latter half of 1990, we changed over to a full desktop publishing system usfog Pagemaker 3.1 on a 386 25MHz machine with a large screen. Today, we are using a mixture of 386 and 486 machines to compile the magazine. All pages, including the cover, are made up on screen. The printed circuit boards, the circuits and wiring diagrams are made up using a number of different CAD packages. To achieve this result, there has been a heavy investment in hardware and software and we expect that to continue. Who knows what changes we will see in the next five years - about the only thing which can be predicted with certainty is that the changes will -continue to come thick and fast. Actually, the October 1992 issue was our 60th, so strictly speaking, we could have celebrated our 5th birthday with the publication of the November issue. However, for a number of reasons it had to be moved back to this issue. Hence, we now present our birthday celebration with over $45,000 worth of prizes, including a Ford Festiva sedan. To give everyone plenty of time to enter, the SILICON CHIP 5th Birthday Sweepstakes will run till the end of February 1993: So get your entries in and join in the celebrations. Our special thanks to Jaycar Electronics and the Ford Motor Company, who are the major sponsors of this 5th birthday celebration, and also to the many other companies who are participating. Without their support, this celebration would not have been possible. Leo Simpson Message Stopper Are your customers having trouble getting through to your phone/fax line ? and you've Jost the sale because your exsisting fax switch is not doing what YOU want it to do ? WE HAVE THE SOLUTION! This ine,r;pensive device, which connects direct to your answering machine will automatically disconnect your answering machine whenever ANY PHONE is answered ! If your answering machine answers your call before you do, simply pick. up any phone, your answering machine will immediately disconnect and you can speak. without interference. With the MESSAGE STOPPER you can now leave your answering machine on and not have to worry ! -· The VSI EASY CONNECT Phone-Fax/Line Sharer _j;/' The most advanced Phone-Fax (or Modem) /Line Sharing Device. Now available in Australia. Integrate ANY fax, with ANY answering machine on ANY telephone system, WITHOUT the limitations of faxswitch devices or 3 in I fax systems. Only$39.95 Maggy La1n.p Magnify any object under a clear cool ~~o!~sr~e~~jift~~-in. ;p ~ ... With a 127mm biconvex lens, 4 dioptres, focal lenght 245mm, sturdy contruction and built to last ! ' ., · NO NO NO NO Why the EASY-CONNECT 1 Confusing Voice Messages Delays or Periods of Silence Unusual Dial Tones Frustrated Callers Becaue lht Bi\SY-CONNBCT 1, Ille mo1t :i~Jlr11~~e le"vd1/r:.°:l.11e,~ebfehrAne,..:~!~r!W: toda,-. ~:gir: · ,. 1· ' l !~ )' !eo~n n ~-:ere~~ 0 ,;:t'e·i.: r.!ifhou t the llrnl11tlon, of fauwltch device& or 3 ln I ru, &ynem&. Other faxswitch systems ? Clunuy fu; priority operation. Delay,, p111,e1, voice me1111e1 , fr1111tr1tedc1llen. ~~t~et~belvel:e~~ limited operulon with M111t be rlttr:d on rirat socket. Poor hl,cory or c111tomr:r 11tl,f1ctioA. The EASY-CONNECT is totally transparent. Your callers will never know it's on the line I "'' . Don't Pay 1299.00 u-w u-w u-w u-w Dedicated fax line 7 _.More Automatic, More Flcxiblc, More Powerful than a ny 3 in I fax s ystem . Telecom ch ■ r1u errectin 23/6 / 92 without telephone. : ~:,\c:1t1sVi~ic;i:~ii°c'si':n l~~~~11fJN~~~cfi~7,!~ility. -Fully Functional with ALL e.l.lcnsion telephone,. -No rcslriclion to the number or poliilion or extensions. .-Qpcratc with Fax, Phone, Modem, and Answering Machine on one line. _.No switches to remember (or rorgct) when your office is •nallcndcd. •Proven Reliability bactcd up wilb a 2 YEAR EXCHANGE WARRANTY . •PROTECTION tor the Fax. and other devices against lightning or surges. -Austc l Approved. A?0/1 ◄ 8/03 ◄ 2. Made in U.S.A. •Save installation and rental costs for a separate line. ';.~",: ,°j~';~!~~•n~':c:.•t,zrc of ll1l,tnln11trltc1, 1009' prott:.t:.tlon for Jflc f•~ 1 0 I yr:1r :!?':,J:~';ie~:g Te l ecom 14<12 VSI 1399 S1vln1& S4<1 Jye1r1 Syeu1 SISU Sl99 S399 SIIH The VS/ Easy-Connect is not to be confused with other faxswitch systems. Our price: Only $279.00 /r,c:lc.1str-ial Digital :M:ultimeters DMSXL $89.95 .,.lopul Lead Warning. ... 2oomA Fuse . -continuity Beeper. _.Diode Test. -De Volts: 200mV-I000V. .... Accuracy: 0.8%. -Resolution: rno·uv. -Input Imp.: JM ohm. -AC Volts: 200V /S00V. -oc Currcnl: 200uA-200mA . GrResistance: 200-2M ohm. -Display: 3.5 Digit, 0.7•. .-Low Battery Indica tor. a,rJ2 Months Warranty. DMlOXL DM15XL $117.00 $149.95 •Logic Test. _.Input Lead Warning . •I0A Fuse. •200mA Fuse. •Continuity Beeper . .-Diode Test. -oc Volts: 200mV-J000V. -Accuracy: 0.5%. •Resolution: I00uV. •Input Imp.: I0M ohm. -Ac Volts: 200V/750V . .-DC Current: 200uA-I0A . -AC Current: 200uA-I0A . •Resistance: 200-2000M Ohm. -Display: 3.5 Digit, 0.7 •. •Low Battery Indicator. •12 Months Warranty . .., Safety Tester. w Input Lead War nin e. •JOA Fu1e. •200mA Fue. A' Continuity Beeper. Diode Test. •DC Volts: 200mV -I000V . .., Accuracy: 0.7%. .., Resolution: l00uV. .., Input Imp.: I0M ohm. •AC Volts: 200V/750V. !Qr DC Current: 200uA-I0A. • Resistance: 200-20M ohm. •Display: 3.5 Digit, 0.7"'. !Qr Low Battery Indicator . .a-12 Months Warranty. * Input Warning Beeper: Incorrect test lead placement will cause all three meters to issue a warning beeper sound . The warning beeper indiCates that a test lead is in an incorrect position. sarety Tester: The safety tester on the DM10XL aafely detects and displays the presence of particular AC or DC voltage (Pos. or Neg.) levels through a series of LED'a. KINGRAY SA214V VHF/UHF Vidt:o Combint:r Amplifit:r For UHF/VHF TV systems The SA214V remote powered video combiner has been designed to combine and amplify a video output signal from a VCR with VHF/UHF signal for multipoint distribution. You can now have video and TV reception from any wired distribution point in the house. Christmas is just around the corner, and so are the break-in's. Avoid Theft, be Alarmed! (example) UHF Ant. UHF/VHF Ant. Economical Alarm System .-s protection loops Alarm Panel. _. Di1it1I Acccu Kc1•P1d. _.Passi've lnfr ■ -Rcd Detector . _. Power Supply and IJallery . Ar Horn Speak.er ■ nd Panic B11tton. ■r) pain of Reed Switches . ..-fh.p1ndablc. KINGRAY MHW34T/ PKS02 Masthead Amplifit:r For UHF/VHF TV systems 240V Toa-o;::( ••• was SJ49.00 · ·.·•·• l~ PKS02 Now$299.95 Only $125.00 12V DC to 240V AC Compact Disc · Cal/mate 9000 Answering Machine Power Inverter protcctJYe carry bag -Tone Remote Control _.Remote turn-on mcua1e access. ..-Remote -call scrccnin1 -Remote change OOM .-Tolluver. : ~~!~: 0 1:;~c~-ystem -Plus more I Onl $89.00 • Durable, weather resistant padded protcctiYc carry case with adjustable shoulder strap, Poctet for compact disc storace. Oct one for christmss ! I David Reid 127 York St, SYDNEY 2000 Ph: (02) 267 1385 Electronics P.O. Box Q103,SYDNEY 2000 Fax: (02) 261 8905 A.C.N. 001-372-372 _. Suitable for city &. country areas. _.Gain: 28d8 VHF: 34d8 UHF. ..-suitable for combined/seperatc aerials. _. Rasy iutallalion . ■r Designed &. Made in Austnli1. _. Power npply included. _. Improve your TV reception. OCTJJO Clamp Mc(cr "Measure AC and DC current" .-AC/DC Amps (400A). •AC/DC Volt,. ..- Resista nce. • Temperature. •Data Hold. •Peal Hold. • Probes Included . ..-c,,e Included. ..-1 yc1r warranty. Only $178.50 ott.•~• +.•~•'c. 0 Postal Charges $5 • $25 "'""" $4.00 $26 • $50 """ $6.00 $51 - $100 '"" $7.00 $101 · $499 ,. $9,00 $500 • ............ FREEi SILICON CHIP, PO Box 139, Collaroy Beach 2097. MAILBAG Magnetostriction oscillators are simple Recently while studying magnetostriction oscillators, I came up with an idea which could be of interest to your readers. As you are aware, all a simple magnetostriction oscillator need consist of is a tuned circuit connected in series with a coil wound coaxially around a rod of magnetostrictive material. Normally, when a tuned circuit is connected to a DC source, free oscillations result which eventually diminish and fade out. But in a magnetostricti ve oscillator, if the frequency of the tuned circuit is the same as the natural frequency of the rod, the oscillations are maintained due to the interaction of stresses in the rod. Of course, in order for the rod to oscillate at the natural frequency, some form of magnetic basis is necessary such as that provided from permanent magnets. This information is well known but it is my belief that it should be possible to make the circuit oscillate without the use of a DC source. This can be simply done by charging the capacitor of the tuned circuit before connecting and closing it to the tuned circuit. The capacitor will then discharge into the inductor of the tuned circuit, setting up free oscillations. If this is done, a very interesting situation will have been created as the tuned circuit will oscillate indefinitely even though there would be no external power source of any kind to replace the losses of the circuit. Hence over time more energy would be created than was originally stored in the capacitor, although thf) energy generated during each cycle would be minute. I believe that this is an unlikely proposition but by using the information I have available I can see no reason why it should not work. The idea could even be expanded to generate energy on a commercial level by use of magnetic coupling, DC pulses, and electromagnets. M. Harkess, Southshore, NZ. Comment: This topic is potentially quite interesting but your proposed method of excitation of such an oscillator cannot provide continuous operation; that is impossible. If it was possible, it would be the first ever example of perpetual motion. Losses in any system always prevent continuous operation if a power source is not present. And if you wish to take energy out, you must put energy in, to maintain oscillation. Nostalgia in telephone terminology On page 46 of the Serviceman's Log in the November 1992 issue, the writer refers to the incoming phone line as being marked "R" and "T". This is a carry over from the days when telephones were large wooden cabinets that hung on the wall. Each telephone line circuit ended up at a socket at the local switchboard. Just why this hole became known as a "jack" has always puzzled me. Another term which still lives today is the "phonejack", for any of a family of round sockets The connections at the jack included two line wires and a supervisory wire. The line wires were Tip and Ring, with the Sleeve being the supervisory connection. The plug and socket were of almost exactly the same dimensions as today's 6mm headphone plugs (and you always thought phone plug was an abbreviation of headphone plug). To this day, older phone technicians might still be heard talking of the tip and ring when referring to telephone lines. Thanks for an interesting column each month; it is usually the first thing I read. W. G. Neumann, Yeerongpilly, Qld. YOU AN NOW AFFORD A .SATELLITE TV SYSTEM $ 995 For many years you have probably looked at satellite TV systems and thought "one day". You can now purchase the following K-band system for only: 6 SILICON CH IP Here's what you get: • A 1.6 metre prime focus dish antenna. complete with all the mounting hardware. • One super low-noise LNB (1.4dB or better). • One Ku-band feedhorn and a magnetic signal polariser. • 30 metres of low-loss coaxial cable with a single pair control line. • lnfrared remote control pre programmed satellite receiver with selectable IF & audio bandwidth, polarity & digital readout. Your receiver is pre-programmed to the popular OPTUS transponders via the internal memory. AV-COMM Pty Ltd, PO Box 225, Balgowlah NSW 2093. Pb: (02) 949 7417. Fax: (02) 949 7095. Al I items are available separately. Ask about our C-band LNBs, NTSC-to-PAL converters, video time date generators, FM2 &EPAL & Pay TV hardware. GEs GARRY, please send me more information on K-band ~ I satellite systems. I Name: _ _ _ _ _ _ _ _ _ _ _ _ __ I Address: _ _ _ _ _ _ _ _ _ _ _ __ 1 I --------- P'code: ---- 1 Phone: _ __ _ _ __ _ _ _ _ __ I ACN 002 174 478 10192 Introducing the DAS-1600. Fasten your seatbelts. Turbocharged data acquisition performance at an economy price-only $1,675. When we introduced the DAS-16 in the early '80s, it raced quickly into the top spot among general purpose data acquisition boards. Well, here we go again. We've just taken the wraps off the next generation: the DAS-1600. A board with break-through performance and the be st software support in the industry. For the incredible price of $1,675 - less than our original DAS-16. Packed with advanced features you need for the '90s. Including: □ 100 Ksample/sec with 12-bit resolution. □ Burst mode to simulate simultaneous sample and hold. □ 8 differential or 16 single-ended analog inputs. □ 32 bits of digital 1/0. □ 2,12-bit D/As with Prices exclude sales tax which may apply. 5 selectable ranges for greater flexibility. □ Advanced ASIC design for lower cost and higher reliability. □ High-quality four-layer printed circuit board for reduced noise. □ Pop Up Control Panel for quick start-up. □ Optional Wmdows® 3.1 software. □ Extensive third-party software support. . ~ Special "Fast Track" offer. • ~ $520 off new EASYEST AGTM software from Keithley Asyst when you buy a DAS-1600 board by Oct. 31, 1992. Get quick start-up, troubleshooting, acquisition to disk, and graphics for only $140 (normally $660). With a price of $1,675, and an offer like this, the DAS-1600 will go even faster.· NILSEN INSTRUMENTS PTY. LTD. • NILSEN Melb (03) 419 9999 Syd (02) 888 8777 Aoel (08) 268 2300 Bris (07) 252 5231 Perth (09) 443 1522. Ten years of the Compact Disc Introduced at the end of 1982, the Compact Disc has now become so popular all over the world that it can justifiably be described as the most successful audio development of the century. This story gives some of its history. ruary 1983, more than 35,000 CD players were sold in Japan, from manufacturers such as Sony, Marantz (Philips), Hitachi, Denon, Sharp, Pioneer, Technics, Onkyo and Kenwood, along with 5 million CDs, making an average of 14 per CD player. World standardisation While slow to begin with, sales of Compact Discs eventually exceeded all expectations. Prior to its introduction in 1982, Sony and Philips were hoping that more than 10 million CDs would be sold worldwide in 1985 but within a year they had revised their forecast to 15 million. Sony went as far as to predict that sales of 20 million CDs could be achieved in 1985. In the end, however, everyone proved to be way off the mark, as CD sales in 1985 totalled 59 million, rising to 136 million in 1986. Sales of CD players also rose rapidly, totalling 3 million in 1985 and 9 million in 1986, a number that earlier Philips forecasts had suggested would not be reached until 1990. 8 SILICON CHIP The Compact Disc was jointly developed by Philips and Sony, and was launched on the Japanese market in November 1982 and four months later in Europe, the USA and Australia. At its European launch, the General Manager of Sony's HiFi Audio Division, Noboyuki Idei, called the Compact Disc "the sound carrier of the century'' ... "We launched the Compact Disc four months ago in Japan and the reaction from the consumer was far better than we had anticipated. But the ultimate growth of the system will largely depend on the software. So the provision of software is our most important objective for the near future". Between November 1982 and Feb- Philips and Sony were not the only ones working on a "digital gramophone record" at the end of the seventies but most eventually dropped out, leaving only the Philips/Sony combination, JVC and Telefunken still in the race. JVC tried to make a breakthrough with AHD (Audio High Density), the audio counterpart of the VHD (Video High Density) video disc sys- TOP OF THE PAGE: the first Philips CD player to be seen in Australia was the top loading CD200. It was closely followed by the CD202. 1 We have done all we can ... now it's up to you! When we in 1989 decided to design Australia's finest range ofloudspeakers, we soon realised the potential we had on our hands. By designing and building the speakers in Australia, and by using the ultimate drivers available, we could challenge the best loudspeakers from around the world. With this in mind we now set out to achieve our go:tl. The choice of drivers was obvious: DYNAUDIO. They are known the world over as being the finest drivers available. The high cost however, makes their use prohibitive for those speaker manufacturers who only produce mass market speakers. Our intention though, was not to make another mass market range ofloudspeakers, but rather Australia's finest. The next step was to appoint a design team. The ideal team should have not only the best technical qualifications and facilities, but also a great love and appreciation for music. With the design team chosen, work began in February 1990. Now followed an exhaustive but rewarding 14 months of intensive research and development. Numerous prototypes were built and refined until each model fulfilled its objectives: Being the finest in its class. The listening panel comprised not only the design team, but also Hi-Fi critics and leading audio dealers from around the country. Each prototype was compared against the more expensive imported equivalents until the design team was fully satisfied. In June 1991 Australia's finest range of loudspeakers was released : DYNAUDIO IMAGE. WE HAVE DONE AIL WE CAN ..... NOW IT'S UP TO YOU ! Acknowledgements: Acoustical Design: Glen Leembrugen & David Connor , Sydney Australia Dynaudio Drivers: Mark Thorup & Peter Larsen, Skanderbarg Denmark So/en Capaciwrs: Dennis QueUet, Quebec Canada Bi-wiring Terniinals : Ben Fan, Taipei Taiwan Monster Cable : Noel Lee , San Fransisco USA Cabinet Builder: Scott Krix, Hackham South Australia Listemng Panel: Glen Leembruggen, David Connor, Pat Hayes, Les Cardilini, Philippe Luder, Dahl Murphy, Carlo Di Martino, Craig McNeil, Michael Henriksen , David.Jacobs , Tom Manning For more infunnation and name of nearest dealer please contact: Scan Audio Pty. Ltd. , P.O. Box 242, Hawthorn Vic 3122 Ph. (03) 429 2199 Fax (03) 429 9309 The or~ginal model released in early 1983 by Sony in Australia was the CDP101. Retailing for more than $1000, it came with a remote control. ' while Telefunken attempted to tern, do the same with the "Mini Disc" (mechanical scanning and 14-bit resolution). But both JVC and Telefunken finally had to concede victory to the Compact Disc. In its original form, the Compact Disc developed by Philips had a diameter of 11. 5cm and a resolution of · 14 bits (16,384 digital steps). Sony's DAD, the Digital Audio Disc, had a 30cm diameter disc - like the LP which could contain over 13 hours of music. Nb company apart from Philips had hit upon the idea of developing a much smaller disc. Philips and Sony jointly decided to increase the diameter and resolution of the Compact Disc to 12cm and 16 bits respectively (65,536 digital steps). The slightly larger diameter was necessary for a longer playing time (the story goes that Beethoven's 9th, which is very popular in Japan, had to fit onto one CD) but had to be kept small enough to ensure that it would still fit into the wide breast pocket of the Japanese shirt. They also decided to increase to resolution from 14 to 16 bits, despite - 10 SILICON CHIP duction of the video disc (VLP), it had already been suggested that· the principle of the video disc could.be used in the future for a new (analog) optical audio long-play disc. Initially, attempts were made to produce a 4channel audio long-play disc with a playing time of one hour on the basis of broadband frequency modulation. It sounded good but it wasn't ideal. It wasn't until the second half of the seventies, that the idea of recording sound digitally and applying error correction emerged. In 1978, the basic concept ofa Compact Disc with a playing time of one hour was ready and a prototype was shown to Philips' Board of Management. A very important role in promoting the concept was played by Corvan der Klugt, at the time a member of the Board of Management and later on President of Philips. He was convinced that Philips alone would never succeed in making the Compact Disc a world standard. the fact that there were no reasonably priced ·16-bit DI A converters available at the time. The suspicion that critical music lovers would not be satisfied with 14-bit resolution was the deciding factor. Because Philips was not sure that it would have 16-bit Japanese cooperation DI A converters available in time for the CD's introduction, the technique Cooperation with a Japanese comof "oversampling" (digital-filter) was pany seemed to him to be an absolute developed. With this step, Philips ini- necessity. Sony appeared to be the tially attracted criticism from almost most suitable partner, partly because the entire electronics industry, par- of his personal relationship with ticularly Japan. Sony's Akio Morita and that compaThe Japanese, who did not have ny's existing expertise in the field of oversampling, were taken aback by digital technology. In fact, Sony had this development (which fell outside already developed a PCM processor, the CD standard). However, the criti- with which digital tape recordings cism was short-lived, because the could be made. benefits of oversampling became patCorvan der Klugt succeeded in conently clear. Barely two years later, Jap- vincing Morita of the possibilities of · anese CD players with two times over- . the Compact Disc and of the need for sampling appeared, but soon four cooperation and standardisation. This times oversampling was the norm. cooperation between Philips and Sony began officially in the summer of 1979, Initial developments several months after Philips had preLong before anyone had ever sented the Compact Disc to the interthought of the Compact Disc, Philips national press for the first time. was working on a possible successor At the end of the seventies, the to the LP. In 1972, during the intro- Digital Audio Disc Committee (DAD Committee) was founded in Japan. It was a sub-department of MITI, the Japanese Ministry of International " The first Philips CD Trade and Industry. And when, in player was the CDMay 1980, MITI organised a meeting 100, a top loader with spartan facilities. It of the DAD Committee, the demon:was used as the basis stration given by Philips and Sony for many players made such an impression that the sysoriginating from tems presented by rival companies Europe & England. were swept from the table. But although the hardware industry was left with no other option but to accept the licenses offered, the soft- Bitstream is now used in almost all ,Philips CD players and by a large number of other manufacturers. Worldwide success 0 Many early CD players had a vertical front loading format which enabled you to see the spinning disc. However, this configuration was troubled by shock and vibration and quickly gave way to the drawer loading scheme now used universally. ware industry continued to put up a fight. The major record companies decided to boycott the Compact Disc, mainly because of a royalty ofUS$0.03 that Philips and Sony were claiming on each CD. Morita considered drops ping the royalty claim but Philips wouldn't hear of it and they eventually got what they wanted. Convinced of their imminent success, Philips and Sony presented the Compact Disc at the Festival du Son in Paris in March 1981 and a month later gave a spectacular presentation to the press in Salzburg, at the invitation of conductor Herbert von Karajan. Von Karajan himself was so impressed by the Compact Disc's quality and possibilities that he became one of its main promoters. In August 1981, the Compact Disc was presented at the Berlin Funkausstellung, and in October of that year it was the major attraction at the Japanese Audio Fair. At the beginning of 1982 30 licences had been issued to hardware manufacturers and 10 to software manufacturers. In the course of 1982 the Compact Disc was to be seen at exhibitions all over the world. In August 1982, PolyGram's CD factory in Hanover was opened by the pianist Claudio Arrau. Shortly afterwards, the first 300,000 CDs (approximately 150 titles, mainly classical) were shipped to Japan. Directly after the Japanese Audio Fair in October 1982, the Compact Disc was brought onto the market in Japan. DIA converter, the TDA 1541. By combining four times oversampling and noise shaping, a theoretical resolution of 18 bits could be achieved. In Japan, however, some manufacturers, such as Yamaha, were using eight times oversampling and 18~bit converters. Nevertheless, Philips chose to stick with 16 bits, noise shaping and four times oversampling. Bitstream Then Philips introduced a completely new conversion technique, called "Bitstream", at the Electronics Show in Japan in October 1989. With Bitstream DI A conversion, the digital samples are converted with a highspeed (11.28996 MHz) 1-bit DIA converter. The technique is claimed to eliminate the principal causes of non-linearity and zero-crossing distortion in DI A conversion. In Japan, they were so impressed by this advanced technique that a 'Technology Award' was presented to Philips. Ten years after its introduction, the Compact Disc can be considered a gigantic worldwide success. In technical and musical terms, the 1992style CD player is a long way from the models released 10 years ago. Apart from the many new techniques developed for CD and the related improvements in sound quality, ease of use has also been dramatically improved. The Philips CD-100 of 10 years ago could do little more than play, fast search and skip - the latter only very slowly. If we consider the numerous extra options now available (preprogramming, repeat, favourite track selection, etc), together with all the possibilities ofremote control and portable players, it can be said that the CD player has become "the audio machine of the century". It far exceeded Philips' and Sony's wildest dreams. Sales of CDs have increased phenomenally in the last few years. In the Netherlands alone, 39.2 million CDs were sold in 1991, compared with 1.3 million LPs. The number of recordings issued on CD increased from 12,200 in 1989 to 13,000 in 1990 and to 14,300 in 1991. In Australia, some 800,000 CD players have now been sold and 40% of all households have at least one CD player. Worldwide, over 1 billion CDs were sold in 1991, compared with only 170 million LPs. Acknowledgement Our thanks to George Sprague of the Philips Press Office for the material used in this story. SC VIDEO & T.V. SERVICE PERSONNEL TV & VIDEO FAULT LIBRARIES AVAILABLE AS PRINTED MANUALS $85 +P/H BOTH MANUALS T.V. & VIDEO $145 +P/H OR AS A PROGRAM FOR IBM COMPATIBLES OR AS AN APPLICATION PROGRAM FOR D-BASE Ill PLUS FOR MORE INFO. CONTACT TECHNICAL APPLICATIONS PO BOX 137 KENMORE 4069 OR FAX/PHONE (07) 378 1064 Further developments In 1984, Philips produced a 16-bit DECEMBER 1992 11 Diesel sound simulator for model railroads For added realism, why not fit a diesel sound simulator to each of your model locomotives? It's great to see and hear them rolling around the tracks with the sound of the motors rising and falling as they speed up or slow down. By DARREN YATES Well, it was inevitable! After we featured the SteamSound Simulator in the April and September 1991 issues of SILICON CHIP, it didn't take · long for the diesel fraternity to ask "why don't you do the same for diesel locos?" To those of us who prefer steam locomotives, it's almost a case of"why would you bother?" The only problem was that it was the boss who made the final request and after sidestepping the issue for the last 12 months or more, there are only so many medical excuses you can come up with for not doing a project. So I 12 SILICON CHIP came right out and said it: "What a silly project idea"! When I regained consciousness, he reminded me that there are readers who believe that diesels are actually far more interesting than steam locos. So in the interests of remaining fair, impartial and unbiased in any shape, manner or form, I proceeded to do the project. We published a diesel sound generator for model locos some time ago, in the December 1988 issue of SILICON CHIP, but this was intended to be mounted under the layout and could be used with any locomotive scale. This new design can be mounted right inside the loco, provided the scale is HO (1:87) or larger. Mounting the unit inside HO locomotives is made possible by using the 27mm mylar speakers that are now readily available. In addition, we have designed the PC board so that it can be cut in half and folded, if necessary. The design is primarily intended to be used with the pulse width modulated speed controllers described in the April 1988 and April to June 1992 issues of SILICON CHIP, although it can be adapted to other controllers, as described later. Circuit diagram As you can see from Fig.1, the Diesel Sound Simulator contains only two !Cs and a small number of other components. Power is derived from the rails through diode bridge BR1. This is a 1B04 4-pin DIP device capable of providing up to 1 amp. The bridge rectifier feeds diode_Dl and a 100µF capacitor to produce smoothed 4.711 TO TRACK.,. 660k 16 .022 IC1 4046 ZD1 9.1V 400mW 9 vco IN FREQ MAX MIN 11 12 R1 5.6k .,. .,. R2 470k .,. SIG IN COMP IN VCO OUT 16 11 14 - - - - - - - - --1 038 3 12 - - - - - --1028 9 4 ------CKA 04A IC2 4015 DB _____0.1._-+---'l--'-IDA 7 COMP 2 OUT 10 15 15k 5 .,. .,. 8 .,. .,. B 100 EQc VIEWED FROM BELOW .,. DIESEL SOUND SIMULA TOR Fig.1: the circuit of the Diesel Sound Simulator uses a phase lock loop IC connected to an 8~bit shift register to produce the "rumbling" sound. Zener diode ZDl, transistor Qt and diode D2 monitor the back-EMF from the loco's motor to make the pitch of the sound rise and fall with the lo,co's speed. DC which is then regulated to 12V by a 78112 3-terminal regulator. The regulated+ 12V rail powers IC1, IC2 and a power amplifier consisting of four transistors (Q1 Q2, Q3 & Q4). IC1 is a CMOS 4046 phase-locked loop (PLL) which, together with IC2, a CMOS 4015 dual 4-bit shift register, provides most of the circuitry to pro- 811 27mm + 4.7 16VW+ duce the diesel sound. The frequency range of IC1's voltage controlled oscillator (VCO) is set by resistor R1 at pin 11 and resistor R2 at pin 12. By connecting the two clock inputs (pins 1 & 9) of IC2 together and feeding the fourth output of register A into the data in of register B, we've created an 8-bit shift register. The 6th and 7th bits are fed into the SIG IN (pin 14) and COMP IN (pin 3) inputs ofIC1. As a result, the VCO frequency is constantly forced to change back and forth to produce a "rumbling" sound which is taken from pin 2 (COMP OUT) of IC1 via a 15kQ resistor. To provide the effect of turbocharger whine, the VCO output at pin 4 is mixed with the low frequency output via a 27kQ resistor. The mixed high and low frequency signals are then filtered with a 0.22µF capacitor before being fed to the 4-transistor audio amplifier. Speed monitoring The PC board can be separated into two halves which can then be folded together to fit inside the body of the loco. Alternatively, you can mount the board inside a following carriage. As noted above, the frequency of the Diesel Sound Simulator rises and falls in proportion to the motor speed and this gives a very realistic effect. To achieve this effect, we need to monitor the speed of the model locomotive's motor. In practice, we can't monitor the speed directly but we can monitor the motor's back-EMF. The is the voltage produced by the motor which opposes the current flow through it and this voltage is directly proportional to the speed. But how do we separate the motor back-EMF from the voltage applied to it to make it go? You might remember that we said that this sound simulator we designed especially to go with the DECEMBER 1992 13 the amplifier is around 350Hz, although the bass really sounds quite impressive when fed to a large speaker. Construction Take care with the orientation of the two ICs when installing them on the PC board & don't get them mixed up. You can cut the board in half, if necessary, after all the parts have been mounted in position. PWM controllers designed by SILICON CHIP. These controllers produce a pulse output at about 200Hz and have a DC amplitude of about 20V peak. The power to the locomotive is varied over · the full range by varying the width of the pulses. Now since the pulse output from the controller is usually off for 50% or more of the time, that gives us a chance to monitor the back-EMF of the motor because the motor naturally keeps spinning between the pulses and therefore its back-EMF can be measured at these times. The waveform of Fig.2, taken from a motor driven by a PWM controller, demonstrates this effect. You can see the large pulse output of the controller and in between each pulse is a spiky waveform which represents the motor's backEMF. The spikes come from the motor's commutator and brushes by the way. We can monitor the back-EMF by using a circuit which ignores the full pulse output of the speed controller but measures the voltage in between ~~ ~ pulses. This is done using zener diode ZD1, transistor Ql and diode DZ. ZD1 conducts whenever the voltage across the rails is more than about 11 V; ie, whenever high voltage pulses are present. When ZD1 conducts, so does Ql and therefore the monitoring circuit ignores these pulses. At other times, Ql is off and so diode DZ conducts, via the 15kQ resistor, to charge a 4. 7µF capacitor. This capacitor is proportional to the motor speed of the loco and is fed into the VCO IN (pin 9) ofIC1 to control its frequency. Hence, increasing the motor speed increases the VCO frequency and thus the diesel sound rises in pitch. Audio amplifier The audio amplifier is based around transistors Q2-Q5. This is a simple complementary output stage which has a gain of about 5. 7, as set by the 470Q and 2.2kQ resistors connected to the emitter of Q2. The low frequency rolloff is set by the 4.7µF capacitor in series with the 470Q resistor. The actual cutoff frequency for -FEB-1 QQ ? 1? '.'l5 CH1= 500m\/ DC P*1 · win dow w 2m s /d rr " ~ f'l "' 14 L r, .L & fl'' ,, f~ SILICON C H I P lot, . ( ~T fl T., ,~ l - ~~~ ~ Fig.2: this oscilloscope waveform shows the voltage from a PWMspeed controller at a low speed setting. The pulses have an amplitude of about 17V. The spiky waveform between the pulses is the motor backEMF. The hash on the waveform is caused by the brushes & the commutator in the motor. All of the components, except the speaker, are installed on a small PC board measuring 102 x 25mm and coded 09111921. Regardless of how you are going to finally install the unit, we suggest that you build the board ih its supplied form and get it going. Then, if it is necessary, you can cut the board in half to fit it into the loco. Before beginning any constructional work, check the PC board carefully for any shorts or breaks in the tracks. If you find any, use a small artwork knife or a dash of solder to fix the problem as appropriate. When inserting components, start by fitting the two wire links which go under IC2. Next, solder in the resistors. You can use either the standard 0.25W 1 % metal film resistors or Philips MRS16T 0.4W types which have a body that's only 3mm long. If you are using the standard 7mm body (0.25W) resistors, some of them will need to be installed "end on" while the 3mm body types can be installed flush with the board. Our photo shows a mixture of both types ofresistors on the board. If you can't make out the colour bands on the resistors, use your multimeter to make sure of the value. Next, solder in the diodes and the bridge rectifier. The "+" pin on the bridge rectifier package should be.adjacent to the end of the PC board, as shown on the wiring diagram ofFig.3. Make sure that the diodes and electrolytic capacitors are installed with correct polarity. Take care when soldering in the transistors to make sure that they are correctly oriented. Q3 and Q4 have their faces butted together, while. Q2 and Q5 face away from each other. The two CMOS ICs go in last - make sure they are correctly oriented. Testing To test the Diesel Sound Simulator, you'll need to hook it up to your layout with a loco ready to run on the track. This is because the Diesel Sound Simulator relies on the back-EMF produced by the motor to get the correct speed information. We also suggest that you don't use the specified 27mm SIAS (Voc) ·i. ."' I ! > : JU? • •I r"! ! '' JI i l !·!J'"i!_' GEN ■ ii ~ M E N U S :__ = J Power analyser Fully autoranging for voltage, current and frequency. 700VRMS 20ARMS DC-20KHz 0 Accurate measurements to 0.1 % O Accurate with distorted waveforms O Accurate with all power factors O Measures any short term events from inrush current to burst power O PC Software and interfaces provided with most instruments. I • : , ii • he "smart" digital technology in these Voltech analysers and testers, results in measurement made easy. 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'C!:~~![~9h2~se INDUSTRIAL PRODUCTS ro miniature speaker at tnis stage - it is rather fragile and should be handled as little as possible. Use a conventional larger speaker during testing. When you first apply power, and with the speed controller set for minimum output, the Diesel Sound Simulator should be in "idle" mode; ie, simulating the effect of the motor at idle. As the speed setting is increased to make the loco move, the pitch of the diesel sound should begin to rise. Wind up the speed controller to maximum and observe that the diesel sound is still realistic. It should sound like a diesel running at a good pace, not like a motorbike doing 8000RPM. If the maximum diesel pitch is too high, you can reduce it by increasing the value ofRl. Similarly, if the maximum pitch is too low (unlikely), you can increase it by reducing the value ofRl. Similarly, if the idle speed is too CAPACITOR CODES 0 0 0 0 Value IEC Code EIA Code 224 104 223 SPEAKER Fig.3: here's how to install the parts on the PC board. Make sure that you install the wire links before fitting IC2. high, you can reduce it by increasing the value of R2. If the PC board does not work, the most likely reason will be shorts between tracks caused by tiny solder splashes. Careful inspection of the board under a good light with a magnifying glass will locate these problems. Mounting it in a loco As noted above, the Diesel Sound Simulator is intended for locomotives in HO, 00 or larger scales. However, some HO diesel locos are just too small or are so crammed inside that it will not be possible to install the sound components in them. In these cases, the only practical approach will be to install the sound components inside a dummy loco (ie, without a motor) or inside a carriage or wagon. Either way, you must arrange to pick up power from the rails. This can be done from the loco's wheels and then via a miniature 2-way cable and connector. Alternatively, you will need to pick up power from the rails via collectors on the wheels of the dummy loco or wagon. On the hand, if you can possibly manage to fit the sound components inside the loco itself, the effect will be even more realistic. You can then have PARTS LIST 1 PC board, code 09111921, 102 x25mm 1 27mm 8Q Mylar loudspeaker Semiconductors 1 4046 phase-locked loop (IC1) 1 4015 dual 4-bit shift register (IC2) 1 78L 12 + 12V regulator 2 BC548 NPN transistors (01 ,02) 1 BC558 PNP transistor (03) 1 BC337 NPN transistor (04) 1 BC327 PNP transistor (05) 1 9.1V 400mW zener diode (201) 1 1804 bridge rectifier (BR1) 1 1N4004 rectifier diode (01 ) 1 1N914 signal diode (02) Capacitors 1 100µF 35VW electrolytic 1 100µF 16VW electrolytic 1 10µF 16VW electrolytic 2 4. 7µF 25VW electrolytic 1 0.22µF 63VW MKT polyester 1 0.1 µF 63VW MKT polyester 1 .022µF 63VW MKT polyester Resistors (0.25W, 1%) 1 680kQ 1 10kQ 1 470kQ 1 5.6kQ 2 100kQ 1 2.2kQ 2 47kQ 1 1kQ 1 27kQ 1 470Q 2 15kQ 1 4.7Q 0.22µF 0.1µF .022µF 220n 100n 22n 0 0 0 0 0 0 0 0 0 0 0 0 0 No. Value 4-Band Code (1%) 5-Band Code (1%) 1 680kQ 470kQ 100kQ 47kQ 27kQ 15kQ 10kQ 5.6kQ 2.2kQ 1kQ 470Q 4.7Q blue grey yellow brown yellow violet yellow brown brown black yellow brown yellow violet orange brown red violet orange brown brown green orange brown brown black orange brown green blue red brown red red red brown brown black red brown yellow violet brown brown yellow violet gold brown blue grey black orange brown yellow violet black orange brown brown black black orange brown yellow violet black red brown red violet black red brown brown green black red brown brown black black red brown green blue black brown brown red red black brown brown brown black black brown brown yellow violet black black brown yellow violet black silver brown diesel sound all the time, even when the loco is running "light engine" (that's railway speak for when it's running by itself). RESISTOR COLOUR CODES rn 2 2 1 2 SILICON CHIP The prototype fitted neatly inside a HO scale Victorian Railways V/Line G Class Mk2 loco but only after we had relocated the internal wiring for the lighting. To obtain adequate sound output, the loudspeaker should be fitted inside a 30mm length of tubing (not shown here). As a practical exercise, we mounted the Diesel Sound Simulator inside a HO scale Victorian Railways V/Line G Class Mk2 loco. This model is quite roomy inside although it still requires some internal surgery to make everything fit. First, it was necessary to replace the steel weights with lead. Health regulations prevent toy and model suppliers from selling products containing lead but there is nothing to stop model enthusiasts from putting in lead after purchase. It was also necessary to relocate the diodes and the wiring associated with the directional lighting. These diodes were originally terminated to solder lugs under screws which retained the steel weights. We relocated the diodes to a small piece of Veroboard which was then mounted inside the roof above one of the cabins. As noted above, the PC board has been designed to be cut in half if necessary. This is best done with a miniature high speed grinding wheel fitted to a Dremel Moto-tool or an Arlec Mini-tool. This enables you to fold the board in half, with both halves connected together with very short lengths of miniature hook-up wire. The bisected board is then squeezed into the cleared space above the lead weights. We put insulating tape over the lead weight to prevent shorts to the board. Finally, we fixed the speaker inside the roof of the loco adjacent to louvres which conveniently let the sound through. All that you can see in the relevant photos. How did it sound? Not too brilliant - at least not initially. While it was satisfactory at idle, once the loco got going the sound of the motor and following rolling stock tended to drown the sound from the speaker. It really needed a baffle. Hence, after the photos were taken, we mounted the speaker inside a short length of tubing (anything over 30mm long does the job) which is mounted above the unpowered bogie. This can only be done if the top half of the bogie housing (essentially it is a dummy motor) is removed to make space for the tube. That done , the sound output is much louder and is quite satisfactory. Under the layout mounting While the circuit was specifically designed to run with our PWM controller designs, it is possible to use it with other controllers which simply vary smoothed cir unfiltered DC. An example is the simple controller featured in the November 1990 issue of SILICON CHIP. In these cases though, it is not possible to install the system inside the locomotive. Instead it will have to be installed underneath the layout. You can then use a much larger loudspeaker and obtain even more sound output. The circuit will require a few modifications, however. These are as follows: (1). Since the DC from the rails can vary from Oto 12V or thereabouts, the circuit will have to be run from an external power supply which can be a 12V DC plugpack. (2). The anode of diode Dl will need to be disconnected from the bridge rectifier BR1 and connected instead to the positive lead from the external DC power supply. (3). You will probably also have to change the value ofRl to obtain satisfactory operation. We found that 4 7kQ was suitable. Apart from these modifications, the Diesel Sound Simulator is connected as in the loco except that its inputs are wired directly across the track (ie, across the output of your speed controller). Acknowledgement Fig.4: this is the full-size etching pattern for the PC board. Our thanks to Powerline Models Pty Ltd who kindly supplied the V/ Line G Class Mk2 locomotive used in this article. They can be contacted at PO Box 264, Penrith NSW 2750. Phone (047) 396 204. SC D ECE M BE R 1992 17 Want to make something of it? 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This set and forget timer is perfect for clothes irons, electric blankets, heaters, stereo's and other 240V appliances. Adjustable time of approx 2 mins-2 hours. Cat M-7208 ANTENNA TUNER AND QQ RF PREAMP Improve the sensitivity and selectivity of your old shortwave receiver with this easy to build tuner, RF preamp and preselector. Includes all components, hardware, pre-punched silk screen front panel and pre-punched rear panel. AC plugpack optional Cat K-6100 <at>NOV'91 Game Books For Sega, Nintendo or IBM PCs GET THE WINNING EDGEI All the latest and best kept secrets on how to score big points with selected Sega Mega drive, Nintentdo or IBM PC games. They're a great Christmas gift for your favourite space cadet! Priced To Clear Save a bundle on these popular game books. Nintendo Games Players Encyclopedla Vol 1 $14.95 B-9001 Nintendo Games Players Encyclopedia Vol 2 SHORTWAVE ANTENNA KIT Q Get the very best from your equipment with this high-quality shortwave antenna kit. 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You can use it to switch your car or house alarm on & off, or to control lights & other appliances. By GREG SWAIN Although it's mainly intended to switch burglar alarms, this simple project can be used wherever you require a single channel remote control and could even form the heart of a garage door controller. It uses a small hand-held transmitter, has a range of about 100 metres in open air, and uses a receiver that measures just 138 x 42 x 30mm (W x D x H). There are two relays on the receiver board and these are activated each time you press the transmitter button. You can activate the main (or switch) 22 SILICON CHIP relay in one of two modes, depending on how you install a single wire link. If you select momentary mode, the relay turns on when you press the transmitter button and remains on only while the button is held down. It immediately turns off again when the button is released. Alternatively, in latched (or toggle) mode, the main relay changes state on each press of the transmitter button. Press the button once, and the relay turns on. Press it again, and the relay turns off. This mode would be used to switch most burglar alarms on and off, for example. Note: the alarm on/ off inputs should be wired across the normally closed (NO) contacts of the switch relay. The second (or indicator) relay is activated briefly each time the main relay switches on or off, regardless of the mode of operation. When the main relay switches on, the indicator relay closes its normally open (NO) contacts for about 0. 2 seconds. Conversely, when the main relay switches off, it closes its contacts for about 0.1 seconds. This second relay in intended to briefly activate a car's hazard lights, . to indicate whether a burglar alarm is · being turned on or off. The short pulse indicates that the alarm is on; the longer pulse indicates that the alarm is off. most other applications, the "indicator" relay would not be required and so it could be left off the board. In 01 1N4148 18 Cl .001 Al R4 A2 820 C4 6.8pF C3 2•7pF B 17 304MHz SAW FILTER CS 4.7pF 01 2SC3355 E A3 + 'T' ~ A4 12V : ..&.. c2 · .001+ ~ + AS AS IC1 AX5026 A7 A~K AS C E B VIEWED FROM BELOW 16 15 0 R1 111 UHF REMOTE CONTROL TRANSMITTER ~ 9 14 Fig.1: the transmitter is based on trinary encoder ICl. When St is pressed, it generates a series of pulses at its pin 17 output to switch transistor Qt on & off. This transistor is wired as a Hartley oscillator & operates at 304MHz due to its tuned collector load & the SAW filter in the feedback path. The relay contacts are all brought out to a screw terminal block adjacent to one edge of the PC board, along with the supply connections. The main (switch) relay has both NO and NC contacts, while the indicator relay has one set of NO contacts only. SAW resonator Unlike some UHF remote switches, a SAW resonator is used in the transmitter to ensure frequency stability. This SAW filter also makes the transmitter easy to align, since its oscillator will only spring into action and pulse a LED in series with the power supply when the single tuned circuit . is virtually dead on frequency. This clever technique eliminates trial and error adjustments and means that the transmitter can be quickly and accurately alignedto 304MHz (ie, the frequency of the SAW resonator). And although it doesn't directly set the transmitter frequency, the SAW filter will quickly pull the oscillator to 304MHz when it starts oscillating if there is some drift in the transmitter tuned circuit. At the other end of the RF link is a factory-built front-end module that's accurately aligned to the transmitter frequency. This module is fitted with a row of pins along one edge and mounts on the main receiver board just like any other component. It eliminates quite a lot of work, since you don't have to wind any coils or align a receiver front end in order to get the project going. To ensure a compact assembly, the module is entirely made up of surface-mount components. It accepts the signal from the antenna and outputs a digital pulse train which is then fed directly to a digital decoder IC. We'll look more closely at how this decoding circuitry works shortly. How it works -transmitter The transmitter is based on an AX5026 trinary encoder IC - see Fig.1. When pushbutton switch Sl is pressed, this IC generates a sequence of pulses at its output (pin 17). The rate at which these pulses are generated is set by the lMQ timing resistor between pins 15 and 16 (Rl), while the code sequence is set by the connections to the address lines Al-A 12. Each address input (A1-A12) can either be tied high or low or left open circuit (0/C), giving more than half a Main Features Range: ........ .. ...................... ... : ............ 100 metres. Main Relay: ................. ................... ..... Momentary or latched operation. Indicator Relay: .................................. . Pulses on for 0.2s when main (switch) relay turns on; pulses on for 0.1 s when main relay turns off. No. of Code Combinations: ................. 531 ,441. Receiver Current Consumption: ....... ... 1mA approx. (relays off). Receiver Dimensions: .. ....................... 138 x 42 x 30mm (W x D x H). DECEMBER 1992 23 + 0 Fig.2 (left): the receiver circuit is based on a pre-built front-end module. It processes the RF signals from the transmitter & feeds the resultant coded pulse signals to ICl, an AX-528 trinary decoder. This IC then drives the relay circuits via D1 & link LKl for momentary operation, or via flipflop IC2a & link LK2 for latched operation. I 0 ; i. ... a a:~ ,. -> c.., N- + I,--!•· "'C> 0$! 1---1•· oo o~ million possible codes - 531,441 to be exact. The 12-bit code pulses generated by ICl are used to switch transistor Ql. This transistor is connected as a Hartley oscillator operating at 304MHz, as set by parallel tuned circuit 11, C3, C4 & C5. The SAW resonator provides a narrow-band feedback path. Its lowest impedance is at its resonant frequency of 304MHz and thus the tuned collector load must be set to this frequency in order for Ql to oscillate. C3 is used to adjust the centre frequency of the tuned collector load. This point corresponds to maximum current consumption and is found by adjusting C3 to obtain peak brightness from the indicator LED (LED 1). Power for the transmitter is derived from a miniature 12V battery (GP23 or equivalent) and this is connected in series with the pushbutton switch (S1). When S1 is pressed, the current drawn by the circuit is only a few milliamps, the exact figure depending on the code word selected at address lines A1-A12 . I• ... ,-.N ON :::, 0 + I,--!•· O>c, o- a: w > w 0 0 w N:C ><O ....----➔ _,; . ., _... N- w a: _...< ► IC ....I 0 ><Z --'W a: "'0 "' 1- z 0 I• o<> 0 w 0 l- L....IINU\,,.-+-.IJ\-... + o lrl•· ~ .. 0 U)Q w o- a:~ a: ..,.., Oe> LL :c :::, ., ,. IC!;; ...cc-,. How it works - receiver . _... o"' - >< .. < C ., C ... C .., < ... .... C C .... ... C ... C . < ,. N < . . . . . , " ' " ' " ' . . . . . , , , . _ _ . . . . . . , , , . _ _ . . . . . . , , , . _ _ . . . . . . , , " - - ' . . . . . ,1" - - ' . . . . . , , , , . _ _ . . . . . . , , , , . _ _ . . . . . . , , , _ . . . . . , , , _ _ ,, _ _ , 24 SILICON CHIP _ Fig.2 shows the circuit details of the receiver. Its job is to pick-up the coded RF pulses from the transmitter and decode these signals to drive the relays. As already mentioned, the receiver is based on a complete "front end" module which is supplied ready made, tested and aligned to 304MHz. This module processes the received signal · via a bandpass filter, an RF preamplifier, a regenerative detector, an amplifier and a Schmitt trigger. Its input is connected to a short antenna, while its output delivers a digital pulse train that's applied to the input (pin 14) ofICl. ICl is an AX-528 Tristate decoder and is used to decode the 12-bit pulse signal that's generated by the transmitter. As with the AX-5026 encoder, this device has 12 address lines (AlA12) and these are connected to match the transmitter code. If the code sequence on pin 14 of ICl matches its address lines, and the code sequence rate matches its timing (as set by Rl) , the valid transmission output at pin 17 switches high. This then drives the remainder of the circuit via one of two possible paths, to provide either latching (toggle) or momentary operation for switch relay RLYl. For toggle operation, the output from ICl (pin 17) is applied to the clock input (pin 3) offlipflop IC2a via a filter circuit consisting of R2 , R3 & C5. This filter circuit isolates ICl from IC2 and the filtering action of C5 is useful iflong wires are attached to the clock input of IC2 (eg, if the optional manual override circuit is connected). ICZa, a 4013 D-type flipflop, has its Q-bar output conn ected to its data (D) input via R5 to provide toggle operation. Thus, each time pin 17 of !Cl goes high (ie, wh en a valid code is detected), a clock pulse is applied to IC3 and its outputs (pins 1 & 2) toggle. C4 and R5 prevent the flipflop from changing state at less than 1-second intervals. This time constant acts as a debounce circuit and eliminates inadvertent multiple toggling when the transmitter button pressed. Assuming that the circuit is wired in toggle mode, ICZa's Q-bar output (pin 2) drives transistor Ql via R6. When pin 2 of ICZa switches high, Ql turns on and pulls QZ's base low. QZ thus turns on and activates relay RLYl to operate a set of changeover contacts. The relay now remains on until the transmitter button is pressed again. When that happens , ICZa's output switches low and so Ql, QZ and RLYl all turn off. D4 protects QZ by quenching any back-EMF spikes that are generated when RLYl turns off. Momentary operation If momentary operation is selected, ICl 's output is fed directly to Ql via Dl and a lkQ resistor (R4). ICZa is not used for this mode. Now, when the transmitter button is pressed, pin 17 ofICl goes high and Ql, QZ and RLYl all turn on as before. However, when the transmitter button is released, pin 17 of !Cl goes low again and so Ql, QZ and RLYl all turn off. C3, in company with R6 & R7, provides a 1-second switch-off delay when the transmitter button is released. This protects the circuit against drop-outs due to short breaks in the transmission when the transmitter button is pressed (eg, due to contact b ounce). Thus, when momentary operation is selected, RLYl only remains on for as long as the transmitter button is held down. Conversely, when toggle operation is selected, it only changes state each time the transmitter button is pressed. Indicator relay The indicator relay, RLYZ, works differently to RLYl. It is actuated briefly each time Ql (and thus RLYl) changes state, regardless of the mode of operation. Each time Ql turns on, capacitor C7 charges via R12 , DZ, R13 and the base-emitter junction of Q3. As a result, Q3 turns on during this charging period and operates the indicator relay (RLYZ). After about 0.2 seconds, C7 is fully charged and so Q3 and RLYZ turn off again. Similarly, each time Ql turns off, QZ also turns off and capacitor CB charges viaR12 , D3, R13 and the baseemitter junction of Q3 . Q3 and RLYZ thus turn on while CB is charging and turn off again about 0.1 seconds later when the capacitor is fully charged. Resistor RlO discharges C7 when Ql turns off, while Rl 1 discharges CB when QZ turns on. Switch SZ and its accompanying 4.7kQ resistor (R15) provide an optional manual override for the circuit. When SZ is pressed, it provides a positive-going pulse to the clock input of ICZa and so ICZa toggles and switches the relays as described previously. Alternatively, if the circuit is wired for momentary operation, pressing SZ pulls Ql's base high (via R15, RZ, Dl, R4 & R6) for as long as the switch is held down. The receiver module can be powered from any+ 12V DC rail and draws approximately lmA. This rail directly powers the relay driv.er circuitry, since the relays can only w9rk down to about l0V. The front end of the receiver, including the module and the two !Cs, is powered from a +5V rail derived from 3-terminal regulator REGl. PARTS LIST Transmitter 1 transmitter case 1 PC board, 30 x 37mm 1 miniature PC-mount pushbutton switch 1 12V battery, GP23 or equiv. 1 304MHz SAW resonator Semiconductors 1 AX-5026 Tristate encoder (IC1) 1 2SC3355 NPN transistor (01) 1 1N4148 silicon diode (D1) 1 3mm red LED (LED1) Capacitors 2 .001 µF ceramic 1 6.8pF ceramic 1 4.7pF ceramic 1 2-?pF miniature trimmer Resistors (0.25W, 5%) 1 1MQ 1 6.8kQ 1 1kQ 1 150Q 1 82Q Receiver 1 PC board, 137 x 42mm 1 front-end module (aligned to 304MHz) 1 SPOT 12V relay 1 SPST 12V relay 1 7-way PC mount screw terminal block 1 pushbutton switch plus 4.?kQ resistor for manual override (optional, see text) Semiconductors 1 AX-528 Tristate decoder (IC1) 1 4013 dual O-type flipflop (IC2) 1 BC548 NPN transistor (01) 2 2N2907 transistors (02,0 3) 1 78L05 3-terminal regulator (REG1) 1 15V 1W zener diode (ZD 1) 3 1N914 diodes (01,02,03) 2 1N4004 silicon diodes (04,05) Capacitors 1 100µF 16VW PC electrolytic 1 22µF 16VW PC electrolytic 3 10µF 16VW PC electrolytic 1 1µF 16VW PC electrolytic 2 0.1 µF monolithic 2 .0033µF ceramic Resistors (0.25W, 5%) 2 1MQ 1 330kQ 2 180kQ 2 100kQ 1 47kQ 2 10kQ 2 4. ?kQ 1 1kQ 1 10Q DEC EMBER 1992 25 Fig.3: keep all leads as short as possible when installing the parts on the transmitter board & take care with the orientation of the encoder IC. The receiver board can be wired for either momentary or latched operation of relay RLYl by selecting the location of a single link. The indicator relay (RLY2) at right is optional & can be left off the board if not required for your particular applicatjon. Zener diode ZD1 protects the regulator circuit against voltage spikes on the supply line. These spikes typically occur in automotive supply lines and are usually generated the ignition system. R14 and capacitors C6 & C10 provide decoupling from the supply line, while C9 filters the output from the regulator. The receiver has a sensitivity of 2µV for a valid data detect and this input level normally gives a 400mV p-p signal at the test point. This can rise to several volts peak-to-peak with normal input levels. The noise level at the test point (under no signal conditions) is approximately 110mV p-p. Construction Fig.3 shows the assembly details for the transmitter. All the parts, including the battery terminals and the switch (S1), are mounted on a small PC board which fits inside a plastic transmitter case. The most important thing to remember with the transmitter assembly ·is that all component leads should be kept as short as possible. Apart from that, it's simply a matter of installing the parts on the board exactly as shown in Fig.3. Be sure to orient IC1 correctly and note that the flat side of the trimmer capacitor (VC1) is adjacent to one end of the board. The SAW resonator and switch should both be mounted flat against the board, while the transistor should only stand about 1mm proud of the board. The LED should be mounted with its top about 7mm proud of the board, so that it later protrudes about halfway through a matching hole in the lid. Be careful with the orientation of the LED - its anode lead is the longer of the two. Check the board carefully when the assembly is completed - it only takes one wrong component value to upset the circuit operation. This done, slip the board into the bottom half of the case, install the battery and test the circuit by pressing the switch button. Don't worry if the LED doesn't flash at this stage - that probably won't occur because Ql will not be oscillating. To adjust the oscillator stage; press the switch and tune C3 using a plastic tool until the LED does start to flash. When this happens, the oscillator is working and you can then adjust C3 for maximum transmitter output (ie, maximum LED brightness). The lid of the case can now be snapped into position and secured using the small screw supplied. Receiver assembly Fig.4 shows the parts layout on the transmitter board. The first step is to decide whether you want momentary or latched operation for RLY1. Install either link LK1 for momentary operation or link LK2 for latched operation. RESISTOR COLOUR CODE 0 0 0 0 0 0 0 0 0 0 0 0 0 26 No. Value 4-Band Code (5%) 5-Band Code (1%) 3 1 2 2 1 2 1 2 2 1 1 1 1MQ 330kQ 180kQ 100kQ 47kO 10kO 6.8Kn 4.7kO 1kQ 1500 82Q 10n brown black green gold orange orange yellow gold brown grey yellow gold brown black yellow gold yellow violet orange gold brown black orange gold blue grey red gold yellow violet red gold brown black red gold brown green brown gold grey red black gold brown black black gold brown black black yellow brown orange orange black orange brown brown grey black orange brown brown black black orange brown yellow violet black red brown brown black black red brown blue grey black brown brown yellow violet black brown brown brown black black brown brown brown green black black brown grey red black gold brown brown black black gold brown SILICON CHIP TEST . ii RELAY1 CONTACTS Fig.4: the front-end module is installed on the receiver board with its component side facing the adjacent .0033µF capacitor. Install either LK1 for momentary operation of Relay 1 or LK2 for latched operation on Relay 1. The rest of the parts can be installed in any order, although you will find the assembly easier if you leave the larger components till last. These include the relays, terminal block and the front-end module. Make sure that all polarised parts are correctly oriented and that the correct part is used at each location. The front-end module comes with a row of 12 pins along one side and is simply mounted on one end of the PC board. Install the module so that its component side faces capacitor Cl. The trimmer in the module is factory preadjusted (and sealed) for 304MHz operation. It shouldn't ever be necessary to retune the receiver but it can be done by rotating the trimmer (at the top of the board) for maximum voltage at the test point. This voltage can be monitored by connecting a DMM set to AC volts between the test point and ground. However, unless you have a good reason to adjust the tuning, we suggest that you leave the trimmer alone. It's unlikely that you will do any better than the factory adjustment. To obtain a decent range, either a¼wave. or a ½-wave antenna must be connected to the input. This antenna consists of a length of insulated hookup wire and can be either 250mm or 500mm long. The latter will give slightly greater range if this is important. Testing When the assembly is completed, connect the receiver to a 12V DC power supply (a 9V DC plugpack should do) and press the transmitter button. If the project is working cor- rectly, you will immediately hear the relays operating. Check that each relay is operating correctly by connecting a DMM (set to ohms) across its outputs. RLYl should provide momentary or latched operation, depending on whether LKl or LKZ is fitted, while RLYZ's contacts should close briefly each time the transmitter button is pressed. Now check the line-of-sight range of the project. Provided the battery is fresh, it should operate reliably up to about 100 metres in open air, although this can be considerably reduced if the receiver is located indoors, depending on the building material. You can expect a range of 20-30 metres if the receiver is placed inside a car, depending on the location of the antenna. Changing the code Once the project is working correctly, you can code the A1-A12 address lines in both the transmitter and Where To Buy The Kit A complete kit of parts for this project is available from Oatley Electronics, PO Box 89, Oatley, NSW 2223, Australia. Phone (02) 579 4985. The price is $35 for the receiver (includes the frontend module) plus $34 for two transmitters (transmitters available separately for $20 each). Add $4 for packing & postage. Note:·copyright of the PC boards associated with this project is retained by Oatley Electronics. the receiver. You can make this code as elaborate as you like, depending on the security required, but make sure that the transmitter matches the receiver otherwise the unit won't work. Initially, all the A1-A12 address lines will be open circuit but you can tie selected address pins high or low by connecting them to adjacent copper tracks. In both cases, a +5V rail runs adjacent to the inside edge of the address pins, while a ground track runs around the outside edge of the address pins. For example, you might decide to tie Al, A2 and A8 high, tie A3 and A6 low, and leave the rest open circuit. Short wire links can be used to make the connections but note that you will have to scrape away the solder mask from the adjacent rail at each connection point so that the track can be soldered. Troubleshooting If it doesn't work, the first step is to check the supply pins of the two ICs in the receiver. You should find +5V on pin 18 ofICl and on pin 14 ofICZ. If the supply rail is OK, set you DMM to a low AC range, connect it to the test point, and check that the reading increases when you press the transmitter button. If it doesn't, then the receiver module is faulty (unlikely) or the transmitter is suspect. If the reading does increase, set your DMM to DC volts and check that pin 17 of ICl swings high when the transmitter button is pressed. Check the A1-A12 address lines and the timing resistor between pins 15 & 16 if this does not occur. If the reading does go high but neither relay operates, check transistor Ql and its associated base bias resistors (R6 & R7). If only one relay fails to operate, check its associated driver transistor (QZ or Q3). SC DECEMBER 1992 27 COMPUTER BITS BY DARREN YATES Upgrading an AT computer to a 40MHz 386DX motherboard If you're still battling away on an old 286, now is the perfect time to upgrade your machine. Motherboards and hard disc drives have never been cheaper & we'll show you how to put it all together. While 286 machines seemed more than fast enough a few: years ago, they are not much good at running a lot of the newer software, particularly anything that is Windows based. And the standard 40-megabyte hard disc that's been supplied as standard for many years is no longer large enough for many applications. With this in mind, we decided to look at the proposition of upgrading one of our 286 machines to a 386 processor, together with a bigger hard disc. How much could be kept and how much would have to be replaced? The existing machine was in a minitower case and this could be kept along with its 200 watt power supply. The original VGA monitor and video card were also OK and could be kept in service. The existing 5.25-inch 1.2Mb and 3.5-inch 1.44Mb drives were OK as . well. From there on though, it was a matter of out with the old and in with the new. When we surveyed the market, we found that Rod Irving Electronics.had quite a good selection of 386 and 486 motherboards at very competitive prices. So, for this exercise, we chose their 40MHz 386DX motherboard with 128Kb of cache memory. It was priced at $425 plus extra for main memory. Depending on what memory you have on your old motherboard, you may be able to salvage it and use it on 28 SILICON CHIP the new one. We took the new broom approach and went for all new memory (we may want to use the AT board and its memory to upgrade an even older XT ~achine). This 386 motherboard only has room for 1Mb of DIP RAM, but it can handle at least 8Mb of SIPP packages and you can pick these up for about $70-$80 per megabyte. We fitted 4Mb which should be adequate for our current needs. IDE hard drive The next step was to choose a new hard disc drive. You can go two ways. If you're on a really tight budget you can jump to an 85Mb drive fora minimum cost. If your old 40Mb drive was crammed to the eyebrows, 85Mb will seem luxurious. Rod Irving Electronics currently has an 85Mb IDE drive for only $419. On the other hand, for just a few hundred dollars more, you can get a 200Mb drive and thereby get a lot more megabytes per buck. If you think you might need it and can stretch the budget a little more, you would be wise to go for the biggest hard disc drive you can afford. Because our old 40Mb drive wasn't an IDE type, we also needed a new IDE (Integrated Disc Electronics) card. These are quite cheap and you can pick up one which will handle an IDE drive and two floppy discs for around the $35 mark from Rod Irving Electronics. As a bonus, it also provides two serial ports (one 9-pin and one 25-pin), a parallel printer port and a games port. If your present AT machine has only one serial port, getting this IDE card with two ports is a very worthwhile bonus. You will be able to connect a mouse to one port and use the other for a modem or fax card. That pretty well takes care of the hardware but there are a few pitfalls to watch out for. Compatibility The most important thing when choosing a new motherboard/hard disc combination is to make sure they are compatible. The new motherboard should have the new hard disc drive's parameters listed in its BIOS setup program. If you're buying the i;notherboard and drive from the same source, such as Rod Irving Electronics, these details should be taken care of automatically but it is wise to check. If you are buying parts from different sources, check to see if you can get some type of return guarantee if compatibility proves to be a problem. Make sure that you're going to have enough time to do the job - don't start it at 10pm and expect to get it going in 10 minutes. If all goes well, you can expect the job to take at least a couple of hours from start to finish. If you run into problems, it can take a good deal longer. Removing the old board The first step in the conversion is to make sure all the power is disconnected so you don't end up blowing The parts used in the upgrade were a 40MHz 386DX motherboard (left), an 85Mb IDE hard disc drive & an IDE controller card. The latter also handles the two floppy disc drives & includes two serial ports, a parallel printer port & a games port. The parts all came from Rod Irving Electronics. either yourself or the motherboard up. After all, your old 286 board still works and you could use it in something else later on. Disconnect your monitor, printer cables and keyboard as well - you won't be needing them for a while. The only tool you'll need is a Pozidriv No.2 screwdriver - these are similar to a Philips type but they are a much better fit into the heads of Asiansourced crosshead screws. Hence, you. are less likely to strip the heads of the screws if you find a screw that's a bit tight. It's a good idea to write down the colour of each connecting lead and its function as you unplug it. Most motherboards have screen printed labellipg next to each connector to designate its function. You should be able to identify which of your plug-in cards are which. If you have an old MFM hard disc drive c;:ard, you won't need that any more if you've bought an IDE type drive. However, you may still need the cables that connect to your floppy drives. Label each cable so that you know which drive it belongs to. After removing the cards, disconnect the two power connectors from the motherboard, noting which socket they fitted into and their orientation. By now, you should have nothing connected to your old 286 motherboard. However, depending on whether you have a desktop case or a towerstyle case, you may find that you have to remove the disc drives before you can remove the motherboard from the case. In this case, note down the cables which fit into the back of the drives and then remove them. You should be able to remove the screws with a Pozidrive screwdriver and the floppy disc drives should then slide out. Be gentle with the hard disc drive - it should be handled with care to prevent damage. You should now be able to locate the mounting screws for the motherboard. Remove these and you should find that the motherboard moves freely. Our old 286 motherboard had screws as well as plastic fasteners to the side of the tower case. To remove it, we had to first remove the screws and then slide it in a certain direction before lifting it out of the case. Once it's out of the case, place the old motherboard in a non-static plastic bag and pack it away safely. Installing the 386 board Chances are that the holes in the new motherboard and the mounting points in the case will not all line up. Try and get as many to match up as possible. The new motherboard must sit as close to the back of the case as possible, otherwise the metal brackets on the plug-in cards won't line up with the mounting rail. Once the motherboard is in place and screwed down, you can connect the two power plugs to the board. These plugs are polarised and should be labelled and there will be labelling on the motherboard itself to indicate how they are connected. Installing the hard disc Before you install the new hard disc drive, you should find somewhere on it a reference to the number of cylinders (or "CYL" for short), the number of heads, and the number of sectors per track (or" SPT"). Write these numbers down now as they'll be needed during setup time. When it comes to actually installing the drive, you'll find that the mounting holes will match up somewhere along the slot in the 3.5-inch bracket. Your new IDE drive card should come with cables as well. The one for the hard disc drive comes with two header-style sockets. One socket plugs onto the back of the hard disc drive , while the other plugs directly onto a matching connector on the card. Next, you can fit the 4-pin power plug to the other socket at the rear of the drive. You can also reconnect the cables to your floppy disc drives as well. Before you go too much further, this will probably be the best time to reconnect the power and turbo LEDs, the loudspeaker and any remaining leads to the motherboard. Keep the cables neat by lacing them together using plastic cable ties. Note that the lead from the hard disc drive indicator LED plugs into the IDE card. It should sit on the two outer pins towards the edge of the DECEMBER 1992 29 you'll only have the IDE controller and video cards plugged in. If you have any other cards (eg, a fax card), make sure you plug these in as well. Check that you have all the cables back in place and in the right order. Don't worry about the connecting leads to the indicator LEDs for the time being, If they're not right, they won't do any damage or stop the motherboard from running initially. When you're happy that everything is OK, reconnect the power and monitor cables to the case but don't put the lid back ori or reconnect the keyboard just yet. Powering up Access to the standard CMOS setup is obtained by pressing DEL while the computer is booting up & then choosing the appropriate .option. You then enter in the date & time, the hard disc type, the floppy disc details, & the type of video card used. · Now apply power - you should see the on-board power indicator LEP light up. You should• now hear the · familiar click, click, click from tbe loudspeaker as the motherbqard checks the on-board memory. When it's finished, you should end up -With the ;s ystem configuration displayed on the screen (it will be incorrect at this stage); together with a mes·sage about the cache memory if you·r motherboard ltas any. · If the power LED or the turbo LED on the front panel fails to turn on, you. have connected it the wrong around. To correct the problem, switch: the computer off, and reverse the plug connection to the motherboard. ~ay B10S check We changed the system boot-up sequence in the advanced CMOS setup but, as a general rule, you can just use the default settings. board. If that lead uses red and white wires, the red wire should go to the outer pin. If you can't identify the polarities of the leads from the LEDs, connect them to the motherboard anyway. If need be, they can be corrected later. Now install the video and IDE cards into suitable slots on the motherboard 30 SILICON CHIP (it doesn't matter which ones you use , as each card has its own address to ensure it receives the correct information). The sockets for the serial ports can now be attached to the back of the computer and the cables plugged into the matching connectors on the IDE card. If you have just a basic system, then Now that you have the new motherboard up and running, you need to check the internal BIDS settings to make sure that they are correct for your system. The way to do this is by switching your computer off and then on again. While it does its initial memory check, you will get a screen message telling you to press the DEL key to access the CMOS setup. While that message is on, press the DEL key, then select the Standard CMOS Setup option. You will then see a screen that's similar to one of the accompanying photos, depending on the BIOS program that's on your particular motherboard. When you go through the BIOS, you need to make sure that it has the correct drives listed. Usually, this will be a 5.25-inch 1.2Mb floppy designated as drive "A", and either a 720Kb or 1.44Mb 3.5-inch floppy as drive "B". You can change these settings by using the PGE UP and PGE DWN keys • . ~ FLUKE AND PHILIPS - THE GLOBAL ALLIANCE IN TEST & MEASUREMENT IP • •. • FLUKE® • • • J ♦ ♦ • 7 0 • •• . •. ♦ ♦ e • PHILIPS ♦ S E R I E S I I We've improved on a winner If you've waited for the next generation digital muhimeter technology, you've made the right choice. Now there is the new Fluke 70 Series II. We've made the world's most popular OMM's even better. At the top of the line, the new Fluke 79 and 29 blend high-performance features capacitance, frequency, a fast 63-segment bar graph, Lo-Ohms range, Smoot/Jing~, faster ranges - and affordability. At the entry levP./, the new model 70, Fluke's lowest-priced OMM ever, delivers unparalleled Fluke quality and safety. *Basics· Redefined No matter which 70 Series II you choose, you gel simple, one-handed operation. High resolution. And built-in reliabtlity. Automatic Touch Hold® - standard on every model - locks the reading on the display and signals you with a beep. Leaving you free to concentrate on your work, not on your meter. There's also fast autoranging. A quick continuity beeper. Diode test Automatic self-test Overload protection, even in the 10 amp range. And a sleep mode that automatically powers down the meter when you forget to. Best of all, every 70 Series II is a Fluke, /Jacked by a worldwide se,vice network and 3-year warranty. ?: I 'I I Be N 1ivith Fluke and Philips Available from the following Philips Test & Measurement distributors: ALL STATES: George Brown Group, Bestobel\, Dick Smith, Petro Ject NSW: Obiat, Ames Agency, Ebson; David Reid, · OGE Systems, No,ocastnan Electronic Supply, Macalec, Vincom, Blackwoods, Emcorp, Tecnico, Tech·Fast, Auslec, Consultant Technology, Elect.Smith Projects, Stott Industrial Supplies. ACT: John Pope Eleclrical, Aeromotive Maintenance Services VIC: Radio Pans Group, Mektronics, Factory Controls. Black.woods. Emcorp, Technico. OLD: St Lucia Electronics.LE Boughen, Colourview Electronics, Auslec, Thomson Instruments, Nortek, Emcorp, Mass Electronics. SA: Electronic Components & Equipment, AWM. NT: Blackwoods, Industrial Supplies & Swnchgear. WA: Atkins Carlyle, Leda Electronics. TAS: George Harvey Electric. NEW ZEALAND: Control Tech, David Reid, Sinus Enterprises, Dick Srntth Electonics PHILIPS • This lets you type in the specifications for your particular drive. Make sure that you specify the hard disc as the C: drive. Once you've done that, exit the setup and the machine should continue to boot up. Hard disc formatting This view shows the upgraded computer, with the 386 motherboard, IDE controller card & 85Mb hard disc drive in position. Make sure that all cables are plugged in correctly & that the supply connections are correct. but the BIOS will tell you what to do anyway. The next thing is to check which type of hard disc drive you have. Each type of hard disc drive has different parameters depending on its make and capacity. Most BIOS programs have a selection of disc types. Each hard disc type will have three important parameters: (1) the number of cylinders; (2) the number of heads; (3) the number of sectors per track. You now have to match the figures you wrote down earlier to one of the disc types on the list. If you can't find it, you should be able to find the option which says "USER DEFINED". ltS'-DOS Uersion 5.88 Fixed Disk Set«p Progra ■ CC)Copyright "icrosoft Corp. 1983 - 1991 0131 a,tlon Cirrent fixed disk drive: 1 Clloose oae or the following: 1. Create. DOS partition or LQfical DOS )rive Set acth.ie. partition 3. Delete partitfo11 or Logical DOS Drive 4. Display partition infor■ation z. Enter choice: lll Press Esc to exit FDISK 0 This screen appears when you type FDISK during the setting up procedure. By choosing one of the options, you can then partition the hard disc drive as required. Most users will choose to have only a single partition. 32 SILICON CHIP The next thing to do is to format the hard disc. If you are using a new IDE drive, don't do a low-level format. Instead, you should use the DOS utility FDISK. If you don't already have FDISK on a bootable disc , you can use the first disc from your DOS 4.01 or DOS '5 package. If you have DOS 5, insert.the first disc into the drive and then press the RESET button on your computer. It will now boot up from the A: drive and the DOS disc. After a short time, the DOS Install Setup program will appear on rthe screen. Press the F3 key to get out ;mf the program and return to the 'A> prompt. Now type FDISK and press <return>. Once FDISK has loaded in, you'll be presented with various options on partitioning the disc. Most u_sers will simply choose to have a single partition that m_atches the full capacity of the disc. When that option runs toJts · completion, you should see the hard disc LED flash on a couple of times. The hard disc is now ready to be formatted. With your DOS 5 disc still in, you can restart the computer and run through the DOS installation program. As it goes through, you'll get to a point where the setup program says it can't copy DOS to the hard disc 'because it hasn't been formatted. Select the option which says '.'format partition" and press return. This will automatically format the hard disc and then load on the rest of DOS 5 onto the disc. Once it has "finished, you should be able to remove the floppy disc, and reboot the machine from the hard disc to the DOS Shell. You can then load in all your normal i;oftware and enjoy the speed and convenience of a 386-based computer. Note: the prices quoted in this article were current during November 1992. You should check current prices with Rod Irving Electronics before making your purchase decisions. The upgrade described in this article had an all-up cost of about $1000. SC · FOR CHIPS... WOOD FOR CHIPS... WOOD FOR CHIPS... WOOD FOR CHIPS... WOOD FOR CHIPS...WOOD FOR CHIPS... WOOD FOR CHIPS... WOOD FOR CHIPS... Get Into The Christmas Spirit with FREE extras for the stocking! Portasol Professional Soldering Iron See review E.A. April 88. No cords or batteries yet it gives the equivalent of a 1Oto 60W iron. Up to 90 minutes continuous use from a single fill. Tip temperatures as high as 400°G can be set. The kit includes one soldering tip, a hot knife, blowtorch and hot blow. Cap contains aflint lighter. Comes in a handy case (with stand for the iron) almost fits·in your pocket. $69.95 Spare tips are each $12.95 Portasol gas specifically designed for PORTASOL 150g $ 6.95 FREE GAS REFILL for the Chflstmas Stocking! Hakko926 Soldering Station The Hakko 926 is a super-quick heat-up (3 sec cycle) and fast recovery iron offering high quality soldering at lower tip temperatures. The built-in ceramic heater maintains temperature to within 0.5°C of the setting. Yes this is an ADJUSTABLE temperature iron covering the range from 200°G to 480°G using a full wave zerocrossing switching system. Meets Ml L-STD-2000 and operates at safe 24V. 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Fluke 10 $108.00 Fluke 11 $138.00 Fluke 12 $156.00 Fluke 45 $1450.00 New 73-11 $210.00 New 75-ii $312.00 New 77-11 $354.00 Fluke 83 $478.00 Fluke 85 $576.00 Fluke 87 $690.00 ; FREE AClO PACK of Call for tax free pricing ,~{ALL/GA TOR CLIPS for i the·fhflstmas Stocking! you to interactively simulate either the DTE side or OGE side of the communications link. You must find a Seriallest space in the stocking for this PC-based Protocol Screwdriver set! Analyser & Data Serialtest Async is similar to Serialtest, but Is limited to asynconly testing. The package includes Serialtest Async software and custom cabling which works in conjunction with the serial ports on your PC. Une Monitor ~ u:: § $ c.,:J !l:; G er: f2 a German quality and ideal fortoolbox, glovebox or pocket. Includes universal magnetic holder for use with power drills, 5.5x0.8 and 6.5x1 .2 flat, Philips No 1 and2 and Pozidrive No1 and 2 bits. The great thing is that the case acts as a handle for the bits, so it's self contained in a space of only 70x50x15mm $20.50 The new version of Serial/est turns ANY PC into a full-featured serial data protocol analyzer - even laptop and notebook computers for both synchronous and async data. Serial/est unleashes the power ofyour PC for data communications testing with a simple, user-friendly interface and either! The new ComProbe f}lugs in to your printer port. With Sena/test and your PC, there is no longer any need to buy or rent expensive, dedicated protocol analyzers. The Serialtest package includes Serialtest software and Frontline's RS-232 ComProbe™ adapter. The ~ 8.30am to 5.00pm Mon to Fri. 8.00am to 12 noon Saturday. :s. c.,:J ~ (.) ~ u:: § $ Then take a close look at these APPA multimeters. Look familiar? That's because they're sold under different brand names. It's called 'Badge Engineerinq' Appa makes the multimeter, but rt's sold with someone else's name on it. 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ComProbe connects to yo ur computer via the parallel printer port (no need for plug-in cards) and allows Serialtest to work with both synchronous and asynchronous devices. Serialtest's monitor mode shows you exactly what information is flowing between any two serial devices - both data bytes and control signals. Source mode allows Anyone who works with serial data communication needs Serialtest. Field service engineers and system integrators wnl appreciate the portability and ease-of-use. Communication specialists and network supervisors will enjoy the power and flexibility. No matter what the industry, Serialtest will prove to be · an indispensable tool. SerialTest Sync/Async with Comprobe $2480.00 (ex tax) $2536.00( inc tax). Allow$15 P&P. Plug Pack $24.95. SerialTestAsync is still $480.00. Demo disk $10.00 refundable on purchase • Extra tough for industrial users • High energy fuse and PTC protection against overloading_ • 0-ring sealed case, switch aM jacks against dirt and moisture • Protective holster and till stand with lead storage • Test probes have finger shields and s/eevetfplugs • Thick walled ABS case and shock mounted LCO withstands 2m drop on to concrete floor • Unique rotary switch with . bery/ium copper contacts and gofd plated pcb Model 103 & 105 e 4000 count • Digital update twice/second, analog 20 times/sec • 8 Functions - Vdc, Vac, Ade, Aac, Ohms , Diode, Continuity, Frequency, Capacitance • Data hold & Relative functions • 0.5% de accuracy $298.80 $249.00 ex tax R1n1es Vdc <IOOmV, 4V, 40V, 400V, 1OOOV Vac4V, 40V,400V, 750V Ade 4-400mA, 1OA Aac 4-400mA, 1OA Ohms 4000, 4kn, 40kn, 400kQ, 4MQ,40Mn Freguency 1OOHz, 1kHz, 10kHz, 100kHz, 1MHz Capacitance 4nF, 40nF, 400nF, 4µF, 40uF Model 105 has similar specs but with improved accuracy of · 0.1% typ on Vdc and 0.5% at 50Hz $358.80 $299.00 ex tax CIRCUIT NOTEBOOK . Interesting circuit ideas which we have checked but not built and tested. Contributions from readers are welcome and will be paid for at standard rates. Board game countdown timer DISP1 LSD The idea for this circuit was inspired by the Pictionary game and is intended to 1k replace the sandglass timers they use. The circuit is basically a down counter which is preset with a START count of 60 and S2 fed with a 1Hz clock signal. The circuit works like this. IC la and IC1 b form an RS flipflop. When the start button (S2) is pressed, the output at pin 4 of IClb goes high, reverse biasing diode Dl. This allows the clock oscillator consisting ofIClc and ICld to run. When the reset button (Sl) is pressed, the output at pin 3 goes high and so the clock oscillator is disabled. This same high going pulse is cou- 7x330D This circuit employs an LM3909 flasher IC as a power on/low battery indicator. Provided there is adequate supply voltage, the LED will flash at a predetermined rate. Once the voltage falls below this level, the LED stops flashing . Resistors Rl and R2 and trimpot VR1 can be adjusted to indicate "low battery" for voltages between approximately 4.4V and 10V. To adjust the circuit, connect it to a power supply set to the voltage SILICON CHIP 7x330D 5 7 B 1 +5V 13 12 11 10 9 15 14 l b C d I a • IC4 4511 IC5 4511 C 2 D 6 18 ['f ii 4 LE A B C D 5 7 1 2 6 8 ~ ~ +5v----------------+--+--+-+-<......,....., + Power on/low battery indicator ~ 13 12 11 10 9 15 14 abcdefg I 34 DISP2 MSD ~ 1 8 11 14 2 PE 01 02 03 04 10k 5 330k IC2 4510 Cl 270k 16 co 18111421213 18 PE 01 02 ·0s 04 A2 AS 7 CLKU/DRST A1 A2 A3 A4 151094121338 5 Cl co IC3 4510 CLK U/D RST 15 10 9 A1 8 4 7 A4 3 11 1 TANT + 02 1N4148 pled via a O. lµF capacitor to the preset enable pins of counters IC2 and IC3. This loads the counters with the preset value of 60. Pressing the start button then causes the circuit to count down to zero. +V R2 1.5k IC1 Lll3909 5 i C1 + 100-400 18VW - you wish to detect as the "low battery" point and rotate trimpot VR1 The BCD outputs ofIC2 and IC3 are fed to two 4511 7-segment display drivers which drive the 7-segment LED displays. S. Merrifield, Newlyn, Vic. ($20) until the LED just stops flashing. To determine the approximate low battery voltage, use the following formula: V1ow batt = Vsupply X 1.1/1.5 where V1aw batt is the voltage at which each cell is down to 1.1V. For ft 9V battery, this voltage is 6.6V. Capacitor Cl can be varied from 100-400µF to set the LED flash rate - the larger the value the slower the flashing rate. The current drain for the circuit is about 2mA. A. Lazzard, Mitchelton, Qld. ($15) IC1 -----------mos----. Q2 MJ2500 18VAC INPUT 330 + 35VW- Q1 1M 1k 5W BC557 0-20V OUTPUT +5V 0-10A t 214700 + 40VW 10k 10k 5.6k 13 0.47 CURRENT SENSE 0.1 and fed to IC2a where it is compared with a variable reference voltage derived from 5V regulator ICl and potenIC voltage regulator chips such as tiometer VRl. IC2a then controls Q3 the 7805 and LM317 are ideal for load which in turn controls series pass trancurrents up to about 1A. They are sistor Q2. cheap, readily available and have pracVR2 thus ·sets the output voltage tically all the necessary regulating and from the supply. If the output voltage protection circuitry built in. rises above the set value, pin 1 ofIC2a If you want higher load currents, goes low and Q3 & Q2 switch off. the design becomes much more comCurrent limiting is achieved using plicated, requiring (typically) a series comparator IC2b. This compares the pass transistor plus additional cir- voltage generated across the .010 curcuitry to protect it from a variety of rent sense resistor with the reference overload conditions. voltage on its inverting (pin 4) input. The design presented here has a If the voltage across the .010 resistor continuously variable 0-20V DC out- · exceeds 96mV, IC2b reduces the base put and can deliver currents up to current to Q3 and hence Q2, thus about 9.6A. Although it is not as effi- limiting the load current to the set cient as a switchmode power supply, value. it generates far less RF interference The current limit value also deand is probably less touchy in terms pends on the voltage across Q2 , as of output stability under various load sensed by Ql and ZDl. If this voltage conditions. · exceeds 9.7V, the current reduces proOther features of the design include gressively so that Q2 's maximum current limiting and temperature pro- power dissipation remains within the tection for the series pass transistor manufacturer's ratings. (Q2). The output voltage is sampled Under worst case conditions (short by a voltage divider (75kn & 10kO) circuit across output), Q2 may dissi- High-current _ 0-20V power supply pate over 100 watts and so a large heatsink is required for this devic!:). Forced air cooling may also be useful if the power supply is operated at high load currents for prolonged periods. Temperature protection for Q2 is provided by thermistor RTHl which is mounted on the heatsink adjacent to Q2. IC2c monitors the voltage across RTHl and its output in turn feeds current limiting ·comparator IC2b. With the component values shown, the maximum heatsink temperature is limited to about 60°C. The performance of the prototype was very good. Using a generous heatsink for Ql and a large transformer, the unit was tested by operating it continuously at 12V and 9A into a load. There were no signs of stress, even after several hours of operation. By the way, you can make up the . .010 current sense resistor by connecting 10 0.10 resistors in parallel. The remaining parts should all be readily available. H. Nacinovich, Gulgong, NSW. (40) DE C EMBER 1992 35 A-ONE A-ONE A-ONE A-ONE A-ONE ~ Save 10%- off for Ca z0 < ~ ~ ~ ~ ~ PROFESSIONAL CLASS DIGITTAL IIULnllfflR WITH ANALOG BAR GRAPH EDll-189110119 $189.00 Z• . 0I < r.,...., .... Z 0 I < Z 0 < ~ ~ •3¾ Digit, Extra Large LCD. • Analog Bar Graph. 14 Functions with AUTORANGING. DCV,ACV, DAA,ACAand Ohm . Frequency Counter 100Hz (0.1 Hz res) to 1000kHz Capacitance 4nF (1 pF res) to 40µF Diode Forward Voltage Test Audible Continuity Test Adaptor Input (1 mV res) Data and Max/Min Hold Relative Mode Data Store and Recall Warning for incorrect input selected. SPECIFICATIONS VDC 400mV to 1000V, 5 auto ranges, 100µV max resolution, ± 0.5% VAC 400mV, 4V to 750V auto, 5 ranges, 100µV max resolution, ± 1 % ADC 4mA to 400mA auto, 10A, 4 ranges, 1µA max resolution, ±1 %. AAC 4mA to 400mA auto, 10A, 4 ranges, 1µA max resolution, ±1.5%. Ohm 4EODOlloh mt o 4oM o hm, 6 auto ranges, 0.1ohm max resolution, ±0.7%. 81 1 110120 $207.00 3¾ digit, 40 x 60mm large LCD screen with analog bar graph • 0.5% DCV accuracy • Auto power off • Includes: autoranging for frequency test, function annunciators, data hold, max/min/avg record and audible readout. • 8 functions measurement ranges: □ DCV 100µV-1000V □ ACV 100µV-750V □ DCA 0.1µA- 10A □ ACA 0.1µA- 10A □ Resistance 0.10- 40MO □ Audible Continuity Test □ Diode Check □ Frequency Test 1Hz- 4MHz • 3¾ digit, 40 x 60mm large LCD screen with analog bar graph • 0.5% DCV accuracy • Auto power off • Includes: autoranging for frequency test, function annunciators, data hold, max/min/avg record and audible readout and high voltage warning detect. • 12 functions measurement ranges: □ DCV 100µV-1000V □ ACV 100µV- 750V □ DCA0.1µA- 20A □ ACA 0.1µA-20A □ Resistance 0.10-40MO □ Capacitance 1pF-40µF D Audible Continuity Test □ Diode Check □ Transistor hFE Gain □ Frequency Test 1 Hz-4MHz □ Logic Level □ Temperature Test -20°C-1000°C. EDII 83B 110122 $269.00 • 3¾ digit, 40 x 60mm large LCD screen with analog bar graph • 0.5% DCV accuracy • Auto power off • Includes: autoranging for frequency test, function annunciators, data hold, max/min/avg record and audible readout and high voltage warning detect. • True RMS READING FOR ACV and ACA • 12 functions measurement ranges: □ DCV 100µV- 1000V D ACV 100µV- 750V D DCA 0.1µA-10A D ACA 0.1µA- 10A □ Resistance 0.10- 4000MO □ Capacitance 1pF-40µF D Audible Continuity Test □ Diode Check □ Frequency Test 1Hz- 20MHz □ Logic Level □ Inductance Test 1µH-40H □ dBm Modifier FINEST 183 MULTIMETER 110116 $74.00 FEATURES • Display Hold mode • Hold and Low battery annunciators • Splash proof and dust proof case • 3½-digit, 2000 count digital display • DC voltage accuracy within 0.5% • 600V protection in ohms and diode test [FINEST' 3487A 3¾ DIGIT ANALOG BARGRAPH DMM M 0115 $143.00 FEATURES • 3¾ digit large LCD DISPLAY (74.8mm x 31.0mm) • Resolution of 4000 counts • 41 Segment analog bar graph • Data hold • Max/Min stores the highest and lowest readings • Relative display (offset) • Continuity beeper and diode check • Indicators of all functions and all ranges • Frequency measurement up to 40KHz • 10 readings per second conversion rate • Dimension: 162 x 80 x 30 (mm) • Weight: appro. 200g • Overflow indicators: steady "OF" • Polarity: Auto" - " sign on at minus input • Overflow indication: "OF" sign on • Measurement rate: appr. 10 readings per second • Display area: 74.8 x 31.0 mm • Function: indicators: "MAX" "MIN" "HOLD" "BAT" "A'~"'-t::+ ., u •Ill) " II Q "REL' M" "AT" "AC" "-" "K" "Hz" "m" "V" • Range selection: Auto, manual • Low battery: "BAT" sign on below operating voltage • Battery: 9V alkalin or carbon-zinc • Accessories: test leads, instruction manual, battery • Operating temperature: 0C to 40C (below 80% RH) • Storage temperature : - 20°c to 60°C *All Escort DMM comes with 3 year warranty. 'I 11 < :INO-V :INO-V :INO-V :INO-V :INO-V SPECIFICATIONS DC Voltage Range: AC Voltage Range: DC Current: 200mV to 1000V 200mV to 1000V 200µA to 10mA A-ONE A-ONE A-ONE A-ONE A-ONE lSh or Money Q!c~~tDECEMBEA.1M2 SPECIAL SAVE $60 BOTH FOR$398 t ~ ~ ~'¾~Tu.\\\;,' '' ~--44..."¾:.tf~&,'< ' ~,,:, '"''''" ' '''" \ SM-320 120W STEREOPOWER AMPLIFIER A0001 SM-333 surround sound processor employs the most updated integrated circuits as its heart. It is also equipped with a (DNA) Dynamic Noise Reductor systems IC made by "National Semiconductor" to particularly filter out the annoying noise that is commonly found on tapes or CD disks; therefore (DNA) system is suitable for and has outstanding performance on different video types, CD, LO, or Dolby Surround encoding disks and tapes, etc. The internal noise reduced to its minimum level, to produce ultimate live performance effect. SPECIFICATIONS & ELECTRICAL CHARACTERISTICS: FREQUENCY RESPONSE : 20Hz-20KHz+/-5dB T.H.D. (Front channel) : 0.05% 20Hz-20KHz T.H.D. (Rear channel) :<0.25% Input signal voltage : 0.1V-3.5V(MAX) Front channel output voltage : 0.1V-3.5V(MAX) Input impedance :47Kohms Surround sound output Voltage : 6.6V(MAX) Delay time :5ms-50ms Power : AC240Vat 50Hz Dimensions : Wide 360mm,(14.2in.) Depth 122mm,(4.82in.) Height 53mm,(2.10in.) ' -"y "''"~:~; · __:,: ""' ---~:W<at>~ ' ',, t'- [~ $219 :«.: ~~ (L Front Panel ~ Front Mounting Plate ~ TopCover <at>; Bottom C over l2l SideCover 11; Rear Panel ~.) Hand le Screw 0 M3 x 0.6 x 5 rti., Screw 0 M4 x 0.7 x 12 19" RACK MOUNT CASES Cat. No, Model Panel Width 80308 80309 80310 80311 80312 80313 80314 80315 80316 80317 80318 4U-10 2U- 12 4U-12 3U-14 4U-14 AL-2U- 12 AL-3U-14 AL-4U-12 AL-2U-10 AL-3U-10 AL-4U-10 19.00 19.00 19.00 19.00 19.00 19.00 19.00 19.00 19.00 19.00 19.00 Panel Height 7.00 3.50 7.. 00 5.25 7.00 3.50 5.25 7.00 3.50 5.25 7.00 BLACK RACK FRONT PANELS Cat . No. Model Width Height 80416 2U 19.00 3.50 80417 3U 19.00 5.25 80418 4U 19.00 7.00 Box Width Box Height 6.75 3.25 6.75 5.00 6.75 3.25 5.00 6. 75 3.25 5.00 6.75 16.50 16.50 16.50 16.50 16.50 16.50 16.50 16.50 16. 50 16.50 16.50 UNIT PRICE 13.50 16.50 18.50 UNIT PRICE Box Depth 10.00 12.00 12.00 14.00 14.00 12.00 14.00 12.00 10.00 10.00 10.00 CASE HANDLES Cat. No. M odel 80501 2U 80502 3U 4U 80503 $45.00 $45.00 $52.00 $56.00 $65.00 $82.00 $92.00 $92.00 $72.00 $77.00 $82.00 (PAIR) PRICE 6.50 7.50 8.50 )~ SM-333 VIDEO/AUDIOSURROUND $239 SOUND PROCESSOR A0002 In order to mat ch with t he SURROUND SOUND PROCESSOR, our company has specially designed a 120W Stereo Power Amp. Th is amplifier not only acts as a perfect partner of Surround Sound Processor but also many other audio sources. The special design of all components are soldered on one P.C. Board. SPECIFICATIONS & ELECTRICAL CHARACTERIST ICS: FREQUENCY RESPONSE TOTAL HARMONIC DISTORTION POWER OUTPUT INPUT SENSITIVITY MIG LO HI S/N RATIO LOAD IMPEDANCE POWER CONSUMPTION DIMENSIONS STEREO PRE-AMP WITH MAGNETIC PHONO OR MIC AMPLIFIER S0301 $20,00 : 20Hz-20KHz : LESS THAN 0.1 % : 60W/4 ohms, 33W/8 ohms per channel :10mV :380mV :640mV : BITTER THAN 70dB :40HM·80HM : 130VA : 360mm(W)x75mm(H)x220mm(D) 14"x 3"x 8•5/8" SUPERIOR ELECTRONIC ROULEnE S0212 $37.50 A v.:onderful fun game! Electronic roulette with novel sound effects. Simulates a real roulette game. Very easy to build. Have fun building - have fun using. Dimensions: 6.38" x 6.38" x 1". This small, economical and versatile preami;,lifier uses a low noise integrated circuit to provide a switch selectable RIAA phone equalized amplifier or a microphone amplifier, and uses high-quality resistors and capacitors. SPECIFICATIONS Frequency response: Sensitivity: Phone: Mic: Power supply: Dimensions: 20 Hz to 50 KHz 2.5mVat 47 K 6mVat 10 K AC 18-22V 0.2A transformer or DC 30V 2.75" X 2.38" X 0.5" ~ s ~ :tINO-V :tINO-V :tINO-V :tlNO-V :tlNO-V A-ONE A-ONE A-ONE A-ONE A-ONE Save 10%-off for Ca! 41/z DIGIT HI-PRECISION DPM S0406 $79.50 This precision digital meter is a standalone voltmeter - ammeter or can interface with a computer! 4½ digit 0.55" LED display. Temperature compensated to 100 PPMt'C. Operating temperature range is 0°c to +70°C. , Outputs include BCD data, Busy and strobe. Panel reading can be latched on hold. SPECIFICATIONS Range: DC voltage: 1mVto 2000V DC current: 1 microamp to 20 amps Stability: ±0.025%±2 digits Power requirements: 5 to 6 volts DC at 200ma Dimensions: 4-5/16" (W), 3¼ (DJ, 1¾"(HJ. 31/2 MULTIFUNCTIONAL LCD DPM (WITH HOLD FUNCTION) S0408 $59.50 S0408 Digital Panel Meter which employs high quality AID converter IC as a main device. The IC drives the 3½ digit of LCD digital display directly. By connecting one or two resistors to produce. all range of voltmeter, ohmmeter and currentmeter. Besides, this unit has detail circuit diagram on temperature meter. Frequency meter.. .etc for reference . Being of high impedance due to FET input, and low bias current, the digital panel meter SM series is furnished with the automatic zero adjustment circuit and automatic polarity transfer, with 100 PPMt'C temperature compensated voltage reference, high reliable within 0°-50°C. Input sensitivity of S0408 Digital Panel Meter is DC±199.9mVfor full scale display. Input impedance: 100M ohm. Working voltage of S0408 is DC 9V, 1.BmA. In order to upset the meter's stability and accuracy, a 100ppmt'C temperature Compensated Voltage Reference Diode is employed, to make this meter work, in the best way within 0-50°C. SPECIFICATIONS DC Voltage Range: AC Voltage Range: Thermometer Range: DC Current Range: Capacitance Range: Frequency Counter: Display: 1mV to 1000V 1mV to 1000V 0°C to 100°c 1 microamp to 2 amps 1 pf to 2 microfarads 10 Hz to 20 KHz 3½ digit 15mm high LCD Maximum Indication: -1999 or +1999 Power Supply: DC9V±5% Power Consumption: 16mW Outline Dimensions: 3¾" 0N) x F/a" (HJ x 4-1/16" (DJ. DIN standard This Case meets West German DIN standard. 31/2 MULTIFUNCTIONAL LED DIGITAL PANEL METER S0405 $64.50 This is a high quality device with excellent specifications. Instructions are included to use this instrument as a voltmeter, ammeter, temperature meter, frequency meter and capacitance meter. The accuracy of this meter is ±0.1 %, ±1 digit. Input impedance is 100 megohms. It has high vibration resistance and so can be used in a mobile or portable environment. Resets to zero automatically. The meter is temperature compensated so that' is can be used from Oto + 150 degrees fahrenheit. SPECIFICATIONS DC Voltage Range: 1mV to 1000V AC Voltage Range: 1mVto 1000V Thermometer Range: 0°c to 100°c DC Current Range: 1 microamp to 2 amps Capacitance Range: 1 pf to 2 microfarads Frequency Counter: 10 Hz to 20 KHz Display: 3½ digit 0.5" high LED Maximum Indication: -1999 or +1999 Power Supply: 5 to 6 VDC, 200 ma Dimensions: 3¾" 0N) x F/a" (HJ x 4-1/6" (DJ. This Case meets Germany DIN standard. 41/z DIGIT HI-PRECISION DPM WITH DIN CASE S0407 $89.50 This is essentially our very popular S0406 digital panel meter but in a standard DIN case. Like the S0406, it has a large 0.55" LED readout. It is also temperature compensated to 100 PPMt'C. Operating temperature range is 0° to +70°C. A MEMORY SYSTEM can HOLD the input reading for comparison and monitor. This is a sensitive unit. An input of 1.9999 volts results in full scale display. The unit operates on 5 VDC at 200ma. SPECIFICATIONS Rear outputs: Range: DC voltage: DC current: Accuracy: Power requirements : BCD data, Busy, Strobe 1mVto 2000V 1 microamp to 20 amps ±0.025%±2 digits 5 to 6 volts DC at 200ma Dimensions: 3¾"0N) x F/a"(HJ 4-1/16" (DJ. This Case meets Germany DIN standard. 31/2 DIGITAL PANEL METER S0402 $49.50 S0404 $59.50 These meters use a Teledyne AID converter integrated circuit. The display is a 0.6" LED for high visibility. These kits are easy to assemble and the instructions provide information on how to use the meter as a voltmeter, ammeter, ohmmeter, thermometer, frequency counter or capacitance meter. A red plastic face is provided to enhance viewing contrast. The S0404 has a HOLD FUNCTION, so the last readout can be held! SPECIFICATIONS DC Voltage Range: AC Voltage Range: Thermometer Range: DC Current Range: Capacitance Range: Frequency Counter: Display: Maximum Indication: Power Supply: Dimensions: 1mV to 100V 1mV to 1000V 0°c to 100°c 1 microamp to 2 amps 1 pf to 2 microfarads 10 Hz to 20 KHz 3½ digit 0.5" high LED -1999 or +1999 5 to 6 VDC, 200 ma 4.75" 0N) x 1.75" (HJ x 1.56" (DJ. A-ONE A-ONE A-ONE A-ONE A-ONE ~h or Money Q~~~L™DECEMBER,oo, WALKMAN* BOOSTER/AUX STEREO POWER AMPLIFIER S0328 $54,50 Since it was introduced to the world by Sony in 1979, the Walkman* took music out of the disco and living room and put it, literally, into our hands. It enables us to enjoy music any time, any place, no matter what we are doing. After a decade of continual development and refinement it is now an established Hi-Fi system. It's one handicap is that we must listen via headphones. Although there there are small loudspeaker systems, they are inadequate in one respect or another. The S0328 booster is now available in response to the demand for a Walkman type loudspeaker amplifier. · Each kit comes with signal input socket, output speaker terminals jack. You just need to turn on the S0328 and connect your Walkman to our Booster then you will be ready to enjoy the HI-Fi grade music! SPECIFICATIONS Power Output: 20W Into 4 ohms 8 ohms Per Channel 120W Music Power Frequency Response: 20Hz-20KHz Total Harmonic 0.1% Distortion: Signal to noise ratio: 78dB Aux. Sensitivity: 150mV Walkman/ 150mV CD Sensitivity: 8-16VDC, 12V x 2AC Power Supply: 3-4A *Walkman is the registered trademark of Sony Corporation Japan . 6.5V TO 18V DC 20 AMP. REGULATED POWER SUPPLY (With 4 steps current• limiting & short-circuit protected) S0011 $149.00 The S0011 has been designed to fulfil! the demand for a fully adjustable regulated current limiting and short circuit proof from 6.5 to 18 volt DC20 ampere power supply circuit board. The S0011 uses newly available components whose operating parameters are ideally suited for this application. The components are conservatively rated for long trouble free life even when operated at the specified limits. For instance, the circuit is capable of easily supplying more than the rated 20 amperes of current. The current is limited by the capacity of the transformer used and the heat sink dissipation. The high power series pass transistors, Motorolas' new 2N6274, has such outstanding characteristics that only two are required. This is in comparison with other competing designs which much utilize from 4 to 8 transistors to achieve similar results. The rectified line frequency power is smoothed by two high capacity capacitors. In addition, filtering is further improved by the use of inductance-capacitance networks at the output. These networks, not provided by other designs, prevent high frequency energy and transients from flowing back into the power supply where they may cause impaired performance. SPECIFICATIONS Output voltage: 20-STEP BAR/DOT AUDIO LEVEL METER S0403 $49.50 Our finest LED dual channel level meter. Each channel has 20 LEDs in groups of green, yellow and red to display a range of -57 dB to Output current: Current limiting control: Ripple and noise: Line regulation: Load regulation: Power input source: OdB. It can be used with power amplifiers from 2 to 200 watts. Operates on 12 volts AC or DC. Has a professional looking panel. Power supply components are on a printed circuit board and so requires only the addition of an external transformer. Dimensions are 10-7/8" x 2" x 2-3/8". Dimensions: 6.5 to 18 volts DC (25V max) fully adjustable 20 amperes maximum 4 steps (5, 10, 15 and 20 amperes) 15 millivolts 0.08% + 20 millivolts 0.08% + 20 millivolts 18-20Vn AC 50/60 Hz, 20-30 amperes 8.13" X 7.62" X 3.25" · DC FET SUPPER CLASS 111>11 PRE-AMP S0330 $145.00 The S0330 is a discrete transistor stereo pre-amplifier using FETs in the critical stages for ultra low-noise linear operation. All amplifier stages operate in class A. The circuit is devoid of all signal processing circuits such as tone controls, filters, etc., in orqer to closely approximate a 'straight wire with gain' configuration. The power supply is heavily regulated to provide a low impedance constant voltage source. SPECIFICATIONS Total harmonic Overall (from AUX) less distortion: than 0.01% Frequency response: Overall (AUX to PRE OUTPUT) 10 to 100,000 (at rated output) Hz+0.5dB-1dB Input sensitivity and impedance: (1,000 Hz for rated output) Phono: 47K ohmns. 2mV Outlet level: Rated Output (0.01 % harmonic distortion) Preamplifier output: 1.3V (20V MAX. 0.1 % T.H.D.) Recording output: 130 mV Power requirements: Power voltage: AC 36V x 2 0.2A Dimensions: 9" x 5.88" x 1" >. ; tfj A-ONE>.0 ELECTRONICS PTY LTD 432-434 Kent Street, Sydney NSW 2000. Phone: (02) 267 4819. Fax: (02) 267 4821. A.C.N . 003 882 513. MAIL ORDERS WELCOME: CHEQUE, MONEY ORDER, AMERICAN EXPRESS, BANKCARD,MASTERCARD AND VISA. Phone or write to us for a copy of your price list. Shop hours Mon-Fri 9-5. Sat 9-1. All prices include sales tax. ~ L.., ._ ~........J REMOTE CONTROL BY BOB YOUNG Building & using the low-cost speed controller; Pt.2 The low-cost speed controller presented last month is a surface mount design on a PC board measuring 55 x 38mm. It will be supplied with the surface mount components installed & the board tested. All the constructor has to do is fit the FETs and the servo input lead. The first step in the assembly is to fit a suitable servo lead to match the receiver you intend to use. These leads should be available from your local hobby shop. Modern servo leads usually come as a 200mm ribbon cable fitted with a 3-pin crimp connector. However, each brand ofR/C set seems to use a different connector and they do not follow any convention in lead colouring or lead position. J.R. and Futaba, for example, use Neg, Pos, Signal whereas Sanwa and K.O use Pos, Neg, Signal, so please take care here. Lead colouring is also messy. The usual convention has a dark colour or black for negative, a red \orange for positive and a neutral colour for signal, but don't be fooled. For example, Futaba use Black, Red and White which is logical but J.R. use Brown, Red and Orange (Sig) This version of the speed controller has eight Mosfets connected in parallel but you can use less, depending on the current requirements of the motor. 40 SILICON CHIP which is confusing. Sanwa receivers have Black with Red trace (Pos), Black (Neg) and Black (Sig) which is crazy. I did warn you to be careful! Fig.1 shows the component layout on the top of the PC board and also the location of the three input wiring pins. For those who feel this is all getting too much, fully assembled, tested and tuned units, with the lead fitted, will be available from Silvertone Electronics (see footnote). Those intrepid souls who can cope with this type of confusion should read on. Parallel Mosfets The PC board provides for up to eight power Mosfets connected in parallel to handle high motor currents. The basic concept of this project is to allow the experimenter to fit as many and whatever FETs he can afford, to suit his particular application. IRFZ30s are affordable, yet will cause only a 125mV loss at 10 amps with four in use. If very high current motors are to be · used, eight IRFZ40s will cut the voltage loss in half. Some of the more exotic FETs such as the IRFZ44, SMP60NO6-18, STVHD90 or the new National DMOS NDP 705, 706 range will give even better figures but at a much higher price. Table 1 lists some test results that were obtained using various numbers and types of FETs. The Speed lB controller has been tested with 30 cells at 46A but lack of suitable test motors has prechided testing to higher figures to date. The unit in this test was fitted with 8 x SMP60NO6 FETs (23mQ) and dropped 0.41 V. This voltage drop seems rather high considering that the eight paralleled FETs should have a combined "ON" resistance of 2. 9mQ. Where is all that extra voltage drop coming from? At this point, we must break off for a spot of theory on high current design. PCB and SCHEMATIC CAD I • • -- •:: • •~ m i' .TV. .IFwAMPLIFIE Keeping it cool Fig.3 shows the variation in drainsource resistance (Ros) versus temp era ture for a National NDP705 Mosfet. This illustrates the need for FETs to be kept as cool as possible. If the . temperature is allowed to rise, Ros will rise, increasing the power dissipation across the FETs, which will in turn increase Ros and leads to further heating. At some point, Ros will stabilise but, by this time, considerable power will be lost to the motor as heat losses in the FETs. I might add here that this factor allows FETs to be parallelled, so it is not all bad. In effect, one FET (lowest Ros) in the group will pass more current and warm its junction, thereby increasing Ros and reducing the current. This effect is not perfect in actual operation and some matching of the FETs is recommended for best results at very high currents. However, this problem has other ramifications which must be clearly understood if the full potential of these exotic semiconductors is to be realised. For example, the compartment housing the speed controller must be well ventilated or better still, the FET heatsink tabs should be fully exposed to the slipstream outside the model. Fig.1: here's how the components are mounted on the top of the Speed 1B PC board. The board will be supplied with the zener diode, trimpots & links fitted. All you will have to do is fit the Mosfets & the servo lead. 275C shows that a 2oz, 0.160-inch track (the width of the FET tracks in the Speedlb) will produce a 45°C temperature rise at about 20A. Even though the PC board design has the gate leads cranked outwards, the space between the FET source and drain leads does not allow any greater track width. Thus, I recommend that if you intend to run very EASY-PC • Runs on PC/XT/AT/286/386 with Hercules, CGA, EGA or VGA. • Design Single sided, Double sided and Multilayer boards • Provides Surface Mount support • Standard output includes Dot Matrix/Laser/Inkjet printers, Pen Plotters, Photo-plotters and NC Drill • Award winning EASY-PC is in use in over 12,000 installations in 70 Countries World-Wide Heating of copper tracks • Superbly Easy to use Heat generated in the FETs is only part of the· problem, however. In the unit tested to 46A, the tracks connecting the FETs were almost as hot as the FETs themselves. This was due to the fact that the prototype was constructed from "one ounce" (ie, one ounce per square foot or 35 microns thick) copper laminate and no additio_n al solder or bus wire was applied to these tracks. Thus, the track resistance was really too high for this ~urrent. That's where most of the extra voltage drop was coming from. The production boards for this project will be made from two-ounce copper laminate but that only goes part of the way to solving the problem. Reference to the US MIL STD • Not Copy Protected Options: • 1000 piece Schematic symbol library • Surface Mount symbol library • Gerber Import facility For full info 'phone, fax or write: BTC Fig.2: this diagram shows the surface mount components on the Speed 1B board. Note that some of the resistors are zero-ohm links & were not shown in the circuit published last month. The board comes with all surfacemount components fitted. PO BOX432 GARBUTT 4814 QLD. PH (077) 21 5299 FAX (077) 21 5930 DECEMBER 1992 41 This close-up view shows the surface mount components on the copper side of the board. Note the heavy solder coating applied to the FET tracks. high currents, lay down a very heavy coating of solder over these tracks after the FETs are soldered in place. The PC board supplied is tinned on these tracks , thus providing some additional conductor thickness and allowing this additional solder to be applied. The rest of the PC board is coated with a solder mask which prevents solder being applied to the tracks, but it will help to minimise corrosion in humid atmospheres such as boats. In theory, we should be able to run currents in excess of 30A and hold down the temperature rise to reasonable limits. However, I have effectively doubled the track width by bringing the power leads into the geometric centre of the tracks. This is a bit of a nuisance if a heatsink is to be fitted but is well worth the trouble. As each side carries only half of the current, the current handling capability of the Speed 1B PC board can be around 60A or more with some track reinforcement, without undue temperature rise. The important point in all of this is that the heat generated in the PC board tracks will be conducted up into the FET junctions, resulting in a further increase in Ros and even more losses, so keep those tracks well reinforced if you intend to use very high currents. Balancing currents Since the design of the PC board has the power leads brought to the centre of the FET tracks, they must be mounted symmetrically to achieve the current balance referred to above. So if you are using four FETs, they must be mounted with two on each side of 42 SILICON CHIP The PC board fits into a small plastic case, with the metal tabs of the FETs protruding through a hole in the lid to ensure adequate cooling. the power leads. Incidentally, this is a good rule to observe in any parallel FET PC board layout, as non symmetry in the PC board, particularly in the gate tracks, can cause incorrect load sharing. Having taken such care to mini1.8 ,i 1.6 J,"' ~ z: e u ~ ..."' 1.2 v.., Q ':I -c 2 "' i 0.8 / v" vV lo= '40A VGS = 10V 1· 0.6 -50 -25 0 I 25 50 75 100 125 150 175 TJ, JUNCTION TEMPERATURE ("C) Fig.3: this diagram, taken from data on the National Semiconductor NDP706A, shows the effect of temperature on Ros• As you can see, increasing the junction temperate from 25°C to 100°c increases the ON resistance by about 35% which means that the FETs should be kept as cool as possible. PLUG TO RECEIVER + ► 0:: SPEED CONTROL .......,< w IC 0 ,.... 0 BLACK GREEN Fig.4: suggested wiring arrangement for connecting the Speed 1B board to a typical radio controlled device. mise resistance losses in the speed controller, don't throw it all away in the connecting wiring. When I first began researching the speed controller project, I sought the advice of various modellers who I knew were considered experts in the field. I was regaled with stories of ZkW motors using 30 odd cells and drawing up to 70A. I also read manufacturers' specifications which stated that their speed controllers were good for 1000A or more. Now the question I must ask here is what kind of PC board and interwiring were these people using? We have already discussed the problems of track width so let's now look at the interwiring. Hartland Cables (Aust.) make an 801.25mm PVC coated cable, 4.7mm OD, which they rate at 40A. It is thicker than any cable that I have ever encountered on a commercial speed controller. Once again, if the temperature rises in the interwiring, this will find its way into the FET junctions and increase RosAll of these heat losses will rob the motor of much needed power and result in overall inefficiencies in the system. For currents up to 30A (most modelling applications), there are few problems. However, if you intend to push the system harder than this, the following recommendations are applicable: (1). Keep the FETs well ventilated. (2). If very high currents are required, lay a heavy coating of solder on the FET tracks or, better still, solder tinned copper wire or even solder wick along the tracks to reduce the resistance. (3). Use the best heavy duty cable Table 1 · FET Selection FUSE WIRE SOLDERED TO PCB >< Type Number Voltage Drop Current BUK455-60 8 100mV 25A STHDV90 4 110mV 25A STHDV90 8 60mV 30A SMP60NO6 8 410mV 46A PCB COPPER CONNECTING WIRE SOLDERED TO PCB Fig.5: suggested method for including a fuse in the wiring to the speed controller. Conventional inline fuses are too bulky and have high resistance losses. available for the interconnections and keep the.m short. Choice of FETs The more FETs used, for any given FET type, the lower the Source/Drain voltage drop and therefore the lower the heat dissipated in the FET junctions. The balance here is between cost and performance. Some of the more exotic FETs can cost up to $12, so you can be looking at $100 worth of FETs in an 8-FET unit. Alternatively, much more care can be put into the heatsinking to take advantage of cheaper FETs run at a lower temperature (and thus lower ON resistance). Thus, the IRFZ30s may be attached to small aluminium plates for heatsinking. The BUK455-60A is another useful and cheap FET. Note, however, that heatsinks are not necessary on systems with only moderate current drains, even with only a few FETs fitted. The flight battery can be anything from 4-30 cells. And although there has been no testing beyond 46A to date, I see no reason why the unit will not handle currents much higher than this. The interwiring presents the biggest problem to my mind. For the competition types who want to win at all costs, the sky is the limit. They should fit the very best FETs that money can buy: SMP6DNO6-18 (lBMQ), NDP705A or NDP706A (15MQ), STVDH90 (23MQ). They should also use as many FETs as possible and provide them with airflow cooling. To do this, cut a small hole through the fuselage, hull or car body and mount the circuit board so the FETs are outside, in the airstream. Take care that you don't static zap the Mosfets. Don't remove them from their anti-static bags until you're ready to install them and connect the tip of your soldering iron to the ground track on the PC board (via a clip lead) when soldering their leads. Use heavy gauge wire to connect the speed control to the motor and battery as discussed earlier. The best wire is the multi-strand instrument type cable. It has a very low resistance per foot and is very soft and flexible. The negative battery lead goes to the Mosfet terminals marked MZ , the positive battery lead goes to the positive motor terminal, and the negative motor lead goes to the Mosfet terminals marked "Ml" (Drain) - see Fig.4. Please, please use a fuse in one of the flight battery leads. They may add weight and take up space but this is Table 2 - Fuse Selection B &$Gauge Fusing Current 30 10 28 14.5 27 17.4 26 20.5 24 29.2 preferable to a burned out motor or speed control. The wiring diagram of Fig.4 shows the fuse in the positive lead but anywhere in series will do. There is no track fuse option on SpeedlB and I would strongly suggest that a small PC board fuse, as shown in Fig.5, be constructed and fitted in place of the standard type fuseholder (the latter are bulky and have a higher than desirable resistance). A fuse in which all connections are soldered gives the lowest resistance, even if it is not quite as convenient to use in the field. Table 2 shows the fusing current of different B&S gauges of tinned copper wire. For example, 20-gauge wire has a fusing current of about 58A. It would be a good choice if your motor draws around 35A at the chosen flight battery voltage. Wrap the fuse in fibreglass tape to avoid problems with molten copper splattering everywhere if it blows. Don't forget the diode, capacitor and varistor across the motor terminals. These must be mounted directly across the motor terminals with the shortest leads possible. Yes, I realise that soldering three leads to each terminal is a real pain and that modern commercial speed controllers have the diode built into the speed control module for the customer's convenience. I also realise that by not putting the diode in the unit, the user may be tempted to leave it out. Don't do that. - it will spell disaster for the Mosfets. Next month, I will describe the installation procedure and tell you how to adjust the throttle direction and sensitivity. SC 22 41.2 21 49.3 Where to buy the kit 20 58.6 19 69.7 18 82.4 17 98.6 16 Footnote: a kit of parts for this speed controller will be available from Silvertone Electronics. Phone Bob Young on (02) 533 3517 for pricing details. 117 DECEMBER 1992 43 Build the NUMBER CRUNCHER What can you do with 10 ICs, three LEDs, two displays and a power supply? You can build the Number Cruncher! It chooses a 2-digit number between O and 99, and you have to guess what it is. By GREIG SHERIDAN & DARREN YATES Think of a number between 0 and 99, double it, add 10, take away the number you first though of, divide it by 10 and what do you get? Well, this project isn't quite that clever but it does automatically select a 2-digit number between 1 and 99, stores it away, and then lets you try to guess what it is. Each time you make a guess, it tells you whether your guess is too high or too low. You then make repeated attempts, all the time zeroing in until you finally guess the correct number. So what's the purpose behind it? Well, to be strictly honest, there is no purpose except to teach and entertain! By building the Number Cruncher, you'll learn a good deal about digital electronics and how logic circuits work. And, when you've finished, you'll have a useful game that will entertain the family for hours. There are just three pushbutton switch controls on the Number Cruncher and these are arranged in a row along the bottom of the PC board. The first (bottom left) increments the TENS digit of a 2-digit LED display, while the second increments the UNITS digit. The third pushbutton switch (on the right) is designated MOVE and has a number of functions. When you first apply power, the display is blank and the game defaults to the reset mode. During this time, two "hidden number" counters are clocked by a lOkHz oscillator. These counters form a random number generator which rapidly cycles between 0 and 99. The game progresses to the running mode when you press the MOVE switch. This latches in a random number and illuminates the 7-segment displays with an initial value of 00. You now try to guess the number by incrementing the display using the TENS and UNITS buttons, and then entering the chosen number by pressing the MOVE button again. To the left of the 2-digit display are three LED indicators. These are the result LEDs. If the number you entered is too low, the bottom red LED glows, Similarly, if it is too high, the top red LED glows. You then enter a new number and press the MOVE button again. When you guess the correct number, the centre green LED glows and the game can be restarted by pressing the MOVE button once more. Block diagram Fig.1 shows the block diagram of the Number Cruncher. The clock (IClOa) provides a square-wave with a frequency of about l0kHz. This is used to clock two decade counters (IC5a & IC5b) to provide the random 2-digit number. The counters are stopped when the 44 SILICON CHIP MOVE button is pressed. Two other BCD (binary coded decimal) counters (IC2a & IC2b) are then clocked by the UNITS and TENS switches. Pressing each switch once increments its associated counter. The outputs from these two counters, along with the outputs from the random number counters, are fed into two 4-bit BCD comparators (IC6 & IC7). These two ICs are really the main stars of the project. They compare the values in the two sets of counters and generate an appropriate output, depending on which is higher and which is lower, or whether they are equal. For example, IC6 compares the values from units counters IC2a and IC5a. Similarly, IC7 compares the values from IC2b and IC5b. The outputs from the comparators are then fed into latch IC8 which is clocked whenever the MOVE switch is pressed. The outputs from this latch then feed the LED drivers to indicate "too high", "too low" and "equal". To show you the number you've pressed, the outputs of IC2a and IC2b are fed into two BCD to 7-segment display drivers (IC3 & IC4). These in turn drive two 7-segment displays. Circuit diagram Let's now take a look at the full circuit diagram - see Fig.2. When power is initially applied, an RC network on pin 9 of IClb sets the flipflop so that its Q output (pin 15) is high. This means that the K input (pin 11) will also be high, while Q-bar (pin 14) will initially be low. This blanks the two 7-segment displays by pulling pin 4 of the two 7-segment display drivers (IC3 & IC4) low. The initial high on IClb's Q output does several things. First, it resets the two guess counters, IC2a & IC2b, so that they don't come on with some random number. Second, it resets quad latch stage IC8 and this in turn ensures that LEDs 1-3 are initially extinguished. And third, it enables the two cascaded random number counters which immediately begin counting clock pulses from IClOa. IClOa is part of a 4093 quad NAND Schmitt trigger IC and is configured here as a square-wave oscillator. It oscillates at a frequency of about l0kHz, as set by the .0lµF capacitor and the 8.2kQ feedback resistor. Its output (pin 11) clocks IC5 which INCREMENT UNITS S1 T UNITS I ~ l7 DISPLAY DRIVER IC3 RANDOM COUNTER TOO HIGH UNITS COMPARATOR IC& ICSa CLOCK l 1 LED EQUALS LED LATCH IC8 IC10a RANDOM COUNTER IC5b TENS COMPARATOR IC7 TOO LOW LED INCREMENT TENS S2 TENS T I ~ COUNTER I -_ _.....,__ ___,_ IC2b w:rvtt: IC4 l7 l 1 Fig.1: block diagram of the Number Cruncher. When the MOVE button is pressed, the two random number counters are stopped. The user then tries to guess the hidden number by incrementing counters IC2a & IC2b until the desired number appears on the 7-segment LED displays. The entered number is then compared with the hidden number using IC7 & IC8. is one-half of a 4518 dual BCD UP counter. Thl:l Q4 output from IC5a in turn clocks IC5b, thereby producing a 2-digit UP counter which continuously cycles from 0 to 99. The outputs of counters IC5a & IC5b are fed into the "B" inputs ofIC6 and IC7. These two ICs are CMOS 4585 4bit comparators and it's these devices that tell us whether the input number is too high, too low, or "just right". Debounce switches ICla is one half of a 4027 dual JK flipflop and is used to debounce the MOVE switch (S3). Each time S3 is pressed, it releases the reset on pin 4 and pulls the set input (pin 7) high. PARTS LIST 1 PC board, code SC08110921, 195 x 97mm 4 10mm rubber feet 3 PC-mount piano key switches 1 metre tinned copper wire (for links) 3 BC547 NPN transistors (01 -03) 1 1N4004 silicon diode (D1) 3 1N914 signal diodes (02-04) 2 5mm red LEDs (LED1 ,LED3) 1 5mm green LED (LED2) 2 LTS543 or equivalent commoncathode ?-segment displays Semiconductors 2 4027 dual JK flipflops (IC1 ,IC9) 2 4518 dual 4-bit up counters (IC2,IC5) 2 4511 ?-segment decoders (IC3,IC4) 2 4585 4-bit magnitude comparators (IC6,IC7) 1 40175 quad D latch (IC8) 1 4093 quad Schmitt trigger 2-input NANO gate (IC10) Capacitors 1 100µF 16VW electrolytic 1 0.1 µF 63VW MKT polyester 1 .01 µF 63VW MKT polyester Resistors (0.25W, 1%) 8100kQ 310kn 1 8.2kQ 171kQ DECEMBER 1992 45 01 1N4004 INCREMENT UNITS S1 I ~ 100k 5 3 J IC9b 0 r ~ - 116 10 112 . 11& T I I EN Q ~ lo Q3 R 04 LT 7 l 12 Q2 IC21 4518 1a 3 11 01 CK u ~K477 13 i ( 2 14 I I 6 6 11 4 d 10 2 C 4511 , 9 •I 1,. -!! • 14 ~ ~ P,~k l +V IC10:_l 4093 14 13 '-)1 :ill s 9 _r K 11 01 11 Q2 12 IC51 .~ RANDOM NUMBER CLOCK .8· d 10 BI -!! 41! ,_ 14 04 14 EN 7 10 i1!.. A4 A3 A2 Al INL 9 82 1 03 13 4518 2 1 IC& . 8- >L 4515 OUT 3 D -!-5 I~ < IN 8 OUT ~2 ~ +V 1~:14~ -- - ~ 16 R -- 0.1 11 81 9 82 035 1 83 • 1A . IC7 4515 OUT . • 01 - OUT 12 12 1 :i ... ~ r' s 1 s iiJ D3 I ~ ' 1N914 R ~ ...] R 17 12 EN cm Q 1 £HK!~ 100k B ~ • '-:!I 100k E~C VIEWED FROM BELOW _J! 1 01 3 Q2 4 Q3 5 I 1a I i . . I I 1 B . I 2 C Q4 6 CK ' I 7 A +V 4 13 BI a 13 4511 DEBOUNCE ..I! .!§ 711k 7 b 12 6 11 4 C IC4 8 D ~ NUMBER CRUNCHER SILICON CHIP 2 C: 14 ~ E ~ 04 I I 100k CLK 9 -:I '-,,Cl B O 15 13 CK IC1b 11 K .r8 6 10k K(:.\A I DEBOUNCE -- 1~. C re J R INCREMENT TENS -!' LED3 TOO LOW IC1®~1 ~ 17 100k E ~ 3 ~ ~01 Q3 10 ..,. CLR rf:\A 01 41175 03 A1 A2 A3 A4 10 7 2 15 K '-C,,I' C A mLr- I 14 16 R 11111 Q3 BC547 t-,fMffE 100k 1k Q2 BC547 , ICI I■100k POWER UP RESET LED2 EQUAL E 84 -!! -1: +V 01 3 024 04 '-.!:l7 B ~ I IC5ll EN 10K Q4 15 13 D4 K /'F\A C OUT ~> N 1 CLK ........1 IN > 13 IN 1k Q1 BC547 18 5 < 6 LED1 TOO HIGH f, +V 46 UNITS +V ~5 16 1T .01I i 100 1&VW! IIIIPIAY1 D •• LfJ 7 12 ' IC3 711k 13 I 1 DEBDUNCE 100k Cl 17:\ _ .1 \!:I - +9-1 2V +V d 1• 2 • 9 1 I 15 9 I 14 18 DISPIAY2 Tall .8 d -!! ~K The result is a clean positive-going Now the really tricky 9V pulse on ICla's Q output (pin 1). work is done inside these Thus, when S3 is pressed to start two ICs. Let's see how it all the game, ICla's Q output goes high works. Since we want to guess a and clocks flipflop IClb. This resets IClb which now switches its Q-bar number between 0 and 99, output high and this enables the dis- we ne~d eight bits·to hold play drivers, so that the displays now that number; ie, four bits show "00". At the same time, IClb's Q {or the "units" and four bits output switches low and this releases for the "tens" . the resets on the guess counters, IC2a IC6 compares the lower & IC2b. The enable inputs of IC5a & four bits from IC2a with IC5b are also pulled low and so these those from IC5a (ie, the counters are latched, thus locking in units). The outputs at pins 2, 12 & 13 then indicate the the random number. IC9 is a 4027 dual JK flipflop and results of this comparison. this is used to debounce switches Sl If the units number entered and S2. The resulting pulses from IC9a in (ie, the number on the and IC9b form the clock signals for "A" inputs) is higher than IC2a and IC2b. These counters corre- the random number on the spond to those shown in Fig.1 and are "B" inputs, pin 13 goes used to hold the entered number. Each high. Conversely, if "A" is less press of the appropriate switch applies a single clock pulse to either pin than "B", then pin 12 goes 1 or to pin 9 to increment either the high. And if they are equal, pin 3 goes high. Note that tens or units digits. The 4-bit (Ql-Q4) outputs from each only one of these three outcounter are fed to 4511 7-segment de- puts can be high at any coder/ driver ICs (IC3 & IC4). These time. then drive two 7-segment displays to The latter two outputs indicate the number that's being en- (pins 3 & 12) are coupled to tered. At the same time, the positive- the cascading inputs of the going pulse that results each time an "tens" comparator, IC7, but increment switch is pressed is ap- note that pin 13 of IC6 is plied to diode OR gate D3 & D4. The left disconnected. By dooutput of this OR gate is inverted by • ing this, IC7 is able to disIClOb and resets latch IC8 to extin- tinguish between numbers INCREMENT MOVE guish any result LED (LEDl - LED3) of the same decade. UNITS that may be on from a previous guess. IC7 is also used to compare the outputs of IC2b Fig.3: install the parts on the PC board exactly 8-bit comparator as shown here & note that all the ICs face in the and IC5b. Its three outputs same direction. As well as driving the 7-segment at pins 3, 12 & 13 then give decoders, the outputs ofIC2a and IC2b the result of the overall are also fed into the "A" inputs ofIC6 comparison between the two num- age to set and reset them and do not and IC7 respectively. These two de- bers. Pin 12 goes high if the guess is respond when the switch wipers are vices are 4585 4-bit comparators and too low; pin 13 goes high if the guess held low. The high on pin 2 of IC8 is also fed have been cascaded to form an 8-bit is too high; and pin 3 goes high if the to the J input (pin 10) of IClb. Thus , BCD comparator by tying the cascad- guess is correct. These outputs are fed into IC8, a IClb now has a "high" on its J input ing inputs (pins 4, 5 & 6) appropri40175 quad D latch which is clocked and a "low" on its K input. When the ately high or low. each time the MOVE switch (S3) is MOVE switch is again depressed, the pressed. If the number entered is too resulting clock pulse from IC la causes high, pin 15 of IC8 goes high and IClb to set, sending its Q output (pin turns on LED 1 via transistor Ql. If 15) high and its Q-bar output (pin 14) the number is too low, pin 10 goes low. This causes the displays to blank Fig.2 (left): the two 4-bit magnitude high and lights LED 3 via Q3. again and the game can now be recomparators, IC7 & ICB, form the If the number entered is correct, started by pressing the MOVE button heart of the circuit. These compare pin 2 of IC8 (Ql) goes high and lights once more. the number entered into IC2a & IC2b LED 2. At the same time, Ql-bar (pin with the hidden number in counters 3) goes low and this disables the twq Construction IC5a & IC5b and generate an INCREMENT switches. This occurs beAll of the components for the appropriate output to ·drive quad D cause the switch debounce flipflops Number Cruncher are mounted on a latch ICB. IC8 then drives the (IC9a & IC9b) require a positive volt- PC board coded SC08110921 and indicator LEDs via transistors Qt-Q3. DECEMBER 1992 47 Tt SC08110921 ol codes check the values with your DMM. Note that Dl must be a 1N4004 while D2-D4 are all 1N914s. The two capacitors can be soldered in next, followed by the 't ransistors and the ICs. Be sure to install the correct IC at each location and note that they are all oriented in the same direction. A clean, fine-tipped soldering iron is essential for this job, since many of the tracks run quite close to the IC pins. Don't use a soldering iron that's too big for this job. If you do, you risk damage to the tracks and you will probably wind up with lots of short circuits. Finally, install the LEDs, 7-segment displays and the three switches. Note that the green LED is LED 2 (centre) and check that all the LEDs are correctly oriented (the anode lead is the longer of the two). The 7-segment displays must be installed with their decimal points at bottom right. Switching on lV)o o-fiTI=o;.=~~ a a ~ Fig.4: check your PC board for defects by comparing it to this full-size pattern before installing any of the parts. measuring 195 x 98mm. Fig.3 shows the assembly details. Before actually installing any of the parts, it's a good idea to check the board carefully for etching defects. Repair any defects that you do find, then start the assembly by installing the wire links. It's important to keep these wire 48 SILICON CHIP links as straight as possible, to avoid shorts. If necessary, you can straighten the link wire by clamping one end in a vyce and then stretching it slightly by pulling the other end with a pair or pliers. Once all the links are in, you can install the resistors and the diodes. If you don't know the resistor colour Now for the smoke test but first check your completed board carefully against Fig.3 to ensure that all parts are correct. Everything OK? If so, connect your DMM (set to the mA range) in series with a 9V plugpack supply and apply power to the board. Note: do not use a 12V plugpack supply, as its output may be well in excess of the maximum 15V supply voltage for the CMOS ICs. Initially, none of the displays or LEDs should be on and the current should be less than 5mA (typically about ZmA) . If the current exceeds 5mA, switch off immediately and check for wiring errors. An IC might have been mounted the wrong way around or there could be a short on the copper side of the PC board. If everything checks out so far, press the MOVE button (S3) and check that the display now shows "00". At the same time, the current reading should jump to about 100mA. Now press the INCREMENT buttons (S1 & S2) until the nµmber you want to enter is dis. played and then press the MOVE button (S3). Finally, check that one of the three indicator LEDs lights to indicate whether you're too high, too low or bang on. Do you know anyone who claims to have ESP? You can now put them to the test. SC IBJJj])~-.==:== ,. BACK ISSUES* ··• ..· MONTH YEAR YEAR MONTH . MONTH .. - YEAR MONTH YEAR - *Back issues are $A5 each (incl. postage). Overseas orders add $A 1 per issue for postage. h y, \+: BINl)Ees:..xif; ',: Please send me _ _ SILICON CHIP binder{s) at $A14.95 each (incl. postage). Overseas orders please add $A3.00 each for postage. TOTAL PRICE $A ••·, .,,,,, .·.· (E••••• .,... '"' H 0 New subscription - month to start 0 Renewal - Sub. No. Overseas surface mail Overseas airmail I I I I I I I I I I Gift subscription I<at>" 1 year (12 Issues) 0 $A42 0$A53 0 $A65 0 $A65 0 $A120 0$A84 0 $A105 0 $A130 0 $A130 0 $A240 NZ & PNG (airmail) *1 binder with 1-year subscription; 2 binders with 2-year subscription -~, ..• I . .. YOUR DETAILS - :. ····~· -~ +Y .. .' r------------, RATES (please tick one) · 2 years (24 issues) Australia with binder(s)* . ··-::;-::_·::::/4'." SUBSCRIPTIONS 0 Australia ·,·.· I ., Your Name (PLEASE PRINT) Address I I I I I I I GIFT SUBSCRIPTION DETAILS Month to start Message Gift for: Name ~ (PLEASE PRINT) I I I I I I Address State I I I I I I I I I I Postcode L - - - - - - - - .___ ..J Daytime telephone number Postcode o Cheque/Money Order 0 Card No. I I I I I I 0 Bankcard I I I I I Visa Card Signature 0 I I I I Master Card I I I I I Phone (02) 979 5644 Fax (02) 979 6503 9am-5pm Mon-Fri. Please have your credit card details ready Fax the coupon with your credit card details 24 hours 7 days a week Card expiry date I Mail coupon io: Freepost 25 Silicon Chip Publications PO Box 139, Collaroy Beach 2097 No postage stamp required in Australia DECEMBER 1992 57 MAL-4: Microcontroller Aid for Learning; Pt.2 This month, we publish the complete circuit diagram of the MAL-4 & describe how it all works. It's based on a Motorola 68HC705CB microcontroller. By BARRY ROZEMA As noted last month, the heart of the MAL-4 is the Motorola MC68HC705C8 Microcontroller Unit (MCU). It has the following internal "peripheral" devices: EPROM (7.6K) , RAM (304 bytes), ROM (240 bytes), bootstrap, crystal oscillator & divider, watchdog timer, interrupt timer/coun58 SILICON CHIP ter, synchronous & asynchronous .serial interfaces, three 8-bit ports and one 7-bit input only port. A 2MHz crystal (XTAL1) is connected to the oscillator pins (38 & 39) of the MCU. The MCU divides the crystal frequency by two, giving an internal clock rate of 1MHz or lµs. This means that if an instruction takes five clock cycles to complete, you know how much time it takes (5 x lµs = 5µs). The MC68HC705C8 is a true "single chip microcontroller" and therefore provides no access to the internal busses. Instead, it has four input/output p9rts. The four ports are called (for want of better names) Port A, Port B, Port C & Port D. Ports A, B & Care 8bit bidirectional ports; ie, any bit(s) can be used as an input or output. Port D is a 7-bit input only port (bit 6 is missing). On the MAL-4, the ports have logic switches or logic monitors connected to them. Ports A and D each have eight data switches connected, while ports B and C each have eight LED data monitors. Port A is used as a data bus and has a number of devices connected to it. They are the liquid crystal display (LCD), the hexadecimal keypad and the port A data buffer (U8, a 74LS541). Port A is configured as an input to communicate with the hex keypad and the port A data buffer. It is configured as an output to write to the display and as an input to read from the display. Port B is connected directly to the input/output socket (PLZ). The logic levels on this port are indicated by eight LEDs which are driven by octal inverting buffer U4 (74LS540). This port is configured as an output but can also be configured as an input by the .user. Port C is used as a control port. It is connected to and controls the display, the hex keypad, the port A data buffer, U8 and the loudspeaker. It has 8-bit LED data monitoring like port B, which is driven by octal inverting buffer U3 (74LS540). Port D is an input only port. It is connected to seven data switches in the form of an 8-way DIP switch (DIP SWZ). If a switch is ON, it shorts the input to ground which makes the input low (0). If the switch is OFF, the input is pulled high (1) via a l0kQ resistor (RP2) to +5V. If the appropriate switches are turned off, Port D can also be configured. as a communications port. Port D has a synchronous and asynchronous serial communications interface called the Serial Peripheral Interface (SPI) and Serial Communications Interface (SCI) respectively. The SPI is connected to a 5 or 8-pin DIN socket. This can be used to drive an IBM XT type keyboard or other synchronous serial devices. The Serial Communications Interface is connected to an RS232 line driver IC (U5, a MAX-232) and PL1. This device converts the 5V TTL signals to ±l0V RS232 levels. The MAX232 chip internally generates its own +10V and -lOV supplies to do this. Operation of the display The 16-character 2-line alphanumeric, intelligent, liquid crystal display can provide the full range of ASCII characters. The MAL-4 talks to the display via port A in an 8-bit parallel format. The control lines, R/W, Register Select and Enable are fed from port C. . The display can be disabled by a link (LNKl). Position 1 enables the display by connecting the enable (E) signal to port C bit 4 (PC4). Position 2 disables the display by disconnecting the E signal and ties the E pin on the display low (0V) via the lOkQ pulldown resistor (R28). VRl is a contrast (viewing angle) control (VRl) which places a DC bias on the VO pin of the display. This enables you to adjust the display to suit your particular viewing angle. Operation of the hex keypad The keypad is an 6 x 4, x-y matrix or row/column type. The column is 4bit and it is driven by port C via a 1-of4 decoder (U6a, 74LS139). This pulls each column low in turn. The row is 8-bit and is read by port A via an octal data buffer (U7, a>74LS541). Each of the eight rows are pulled high via a l0kQ resistor (RP3). If no key is pressed, the row will read high (1) for each of the four column scans. If a key is pressed, a row will read a low (0) on a given column scan. The MCU knows which key is pressed by reading the row/column reference. The keypad circuit can be disabled by a link (LNKZ). Position 1 enables the keypad circuit by plac.i ng a low (0) on the enable pins ofU6 and U7. Position 2 disables the keypad circuit by placing a high (1) on the enable pins via a lOkQ pull up resistor (RP3). Operation of port A Port A is an 8-bit input only port connected to the input/output socket (PL2) and to eight data switches in the form of an 8-way DIP switch (DIP SWl). Its operation is the same as the switches on port D. It is read by the Fig.2 (next page): the MAL-4 circuit is built around the MC68HC705CB Microcontroller Unit. It features synchronous & asynchronous serial interfaces and four 8-bit input/output ports. Ports A, B & C are 8-bit bidirectional ports (ie, any bit(s) can be used as an input or output), while Port Dis a 7-bit input only port (bit 6 is missing). PARTS LIST 1 MAL-4 PC board 1 2MHz crystal 1 24-button keypad 2 PC mounting keyswitches 2 8-way DIP switches 4 3AG PC fuse clips 2 3AG 1A fuses 1 60 x 32 x 30mm TO-220 heatsink (DSE Cat. H-3401) 1 8-way 0.2-inch PC-mount screw connector 1 40-pin DIP socket 1 28-pin DIP socket 4 20-pin DIP socket 4 16-pin DIP socket 1 16-pin header plug 1 26-pin header plug 3 3-pin 0.1-inch SIL PCB plug 3 0.1-inch shorting links (to suit above plugs) 1 plug -to suit display 1 socket to suit display 1 5-pin DIN right-angle PCB socket Semiconductors 1 MC68HC705C8S (EPROM version) with monitor program by E.S.D. 1 Seiko M1632 16-character 2line alphanumeric LCD 2 74LS540 octal inverting buffers 2 74LS541 octal buffers 1 74LS139 dual 1-of-4 decoder 1 7805 5V regulator 1 MAX232 line driver 3 BC108, BC548 transistors 1 WO4 1.SA bridge rectifier 4 1N4001 diodes 1 1N914 diodes 17 3mm LEDS 1 3mm high brightness LED Capacitors 1 2200µF 16VW electrolytic 1 1µF 16VW tantalum 11 10µF 16VW tantalum 4 0.1 µF ceramic or monolithic 2 27pF disc ceramic Resistors (0.25W, 1%) 1 10MQ 1 2.7kQ 6 10kQ 17 150Q 1 4.7kQ 1 10Q 3 10kn x 9 SIL resistor packs 2 4.7kQ PC mount trimpots Miscellaneous 3 3mm x 10mm-long machine screws, 3 3mm nuts, 3 3mm ID spring/antishake washers DECEMBER 1992 59 ,! Ii RESET KEY5 C10 1 r +5V !• R22 10k -- R2 10k 02 8C548 C ~ RESET PAO Cl RESET/ S3 PA1 PA2 PA3 ~E PA4 PAS ':" 35 TCMP 37 TCAP 39 j_ I 'f C3 .LxTAL1 27pf 2MHz ':" · C4 PA8 TCMP PA7 TCAP PBO OSC1 PB1 R1 10M P82 38 .l. PB3 OSC2 P84 U2 88HC705C8 27pf + PBS PB8 2 IRQ PB7 IRQ VDD PCO +SY POO lu1 IRQ KEYi ---;;;;-; PDO PD1 R2 10k _,_ P02 I) 1 01 R21 10 -- LNK3 -~ :f~> 2 C 0 .1+ ':" I) R27 10k 29 31 P03 32 PD4 33 PD5 34 P07 38 PC1 PC2 PD2 PC3 PD3 PC4 PD4 PCS PD5 PCS PD7 PC7 +SV I 40 1 .... ar.::i) 04 ( 1N914 • YOO I RESET PAO 18 10 PA1 PAI 17 9 PA2 PA2 16 8 PA3 PA3 15 7 PA4 PA4 14 +5V 8 PAS 5 PAS PAS 4 PA7 12 PBO PBO 11 13 PB1, P81 12 14 PB2 PB2 13 15 PB3 PB3 15 16 PB4I 17 PBS 18 PBB 19 PB7 C,. PB4 18 PBS 17 PB8 18 Al 9 PA1 D2 8 A2 A3 7 PA2 A4 8 PA4 03 D4 24 28 PC2 PC2 21 PC3 23 24 PC4 I PC4 2 23 PCS, PC7 22 3 01 02 02 03 03 08 U1 A8 19 4 PA2' 5 PA3' E2 Ei~PIN2 RP2 -!!o PA3 +SV t 20 PA2 13 A8 I PA4 A10 PAS A11 PA8 A12 I ce PA7 PC2 9 ROWO 08 D8 07 D7 8 ROW1 7 ROW2 08 8 U7 D5 5 15 74LS641 04 04 4 18 D3 03 17 3 02 D2 2 18 01 01 19 1 PA3 14 A9 OE 3 PAI' 04 AS ,-5__~5.., D5 08 05 ROW3 ROW4 ROW5 ROWS ROW7 E2 Ei -t +o VPP E PC3 r-- PA1 12 PC1 PC7 I AO 01 PA7 25 ,PCO .- PCB 00 ~ D7 2764 A7 3 PCOI 22 PAO PAO 11 PC1 I 21 PA7 10 PAS 27 PC3 r PAS 27 2 PAO' 01 04 6 PA4' ua QS 74LS541 OS 13 7 PAS' 08 08 12 8 PA&' 07 07 11 08 08 ~ 4 28 25 ,,...--- t2, 11 PAO -:1:10 .,!30 ':" ... +SY R28 2.7k R3 10k VDD D1 1N4004 GD AC VPP +12V +5V GND +8 SPKR -- 0- - ...... I) 26: 10 0 R 2200i - 4 RS D3 R/W 04 3 05 D8 E 11 PCS 10 PC8 9 LNK1 1,-- GND -YLED -!!3 R20 10k ~8 0 10 ~ GND C15 -:- DS R28 4.7k +5V C 03 BC548 8 PC7 - SILICON CHIP - VOLUME VR2 1k -0 - +5V 10 LED1 ~ POWER ·• ~ 03( 1N4004 rt 2 ':" ~~""h C18 ~ I■ ~ 1::1\ \;J '-::,/ 1N4004 BATTERY WARNING ~ R24 1500 VDD Cl 1 ■ jt IGO '-- PC4 +SV 120 PCO 2 PC1 3 PC2 4 PC3 5 PC4 6 PCS • 7 ·-:- LED2 r.:'\ EOc VIEWED FROM BELOW ':" U9 0 F2 ":" ~ E 60 5 PA4 D1 LCD 02 M1832 B CONTRAST VR1 1k \:;I POWER S1 ~,.:. - --- PA3 VDO +VLED 12 VO 17:\ POWER 0- 8 D2 1N~004 • -- PA2 DO ~ D7 8R1 AC 7 ...~ l coNNECTOR 8 PAI PAS I) VPP S2 PAO ~ 15 114 PC8 8 --.fQL! 0.1+ MAL-4 MICROCONTROLLER vcc D1 01 02 02 03 18 D6 .... RB 08 06 07 D7 DL _ E1 E2 .... 14 12 LED9 K~A V LED& K~A R8 R9 LEDS K~A R7 .... V. .... l2 RIO .... Q8 11 R11 ~10 V,_ V..KLED7 ~A LE08 V K~A .... 04 05 RS 18 03 U3 74LS540 .... 17 15 D4 8x1500 LE010 R4 K ~ A .... V!:j LED4 K~A V LEDS K~A \D PORT C LED MONITORS PCO PC1 PC2 PC3 PC4 PCS PCB PC7 +SV +SY 20 PBO ·- - -- 01 Q1 PB1 · - - - - 02 02 PBO 19 RP1 10k P81 Q3 18 PB2 2 TCAP PB3 · - - - - 04 +SY RP3 10k 1 PB4 6 OS PBS 7 i 2 i : : 3 4 s 7 6 8 PB& 8 9 10 U4 74LSS40 PB7 9 05 08 Q6 07 07 08 E1 E2 08 14 R18 13 R1!. 12 R18 11 i R19 w 7 8 9 10 PAO' PA1' PA3' PB4 LE013 K~ A PA4' w PBS w b PA6' PB6 LE011 K~ A +SV PAS' PA7' 1 P87 PORT B LEO MONITORS ~ 19 6 PA2' LE012 K~ A w 5 4 P83 LE014 K~ A w 3 2 4 3 s 7 8 18 15 14 13 12 11 10 9 + LNK2 I 0 -- I 2 E A B vo 4 8 s r+ 7 ~ ...... C1+ C11 : : 10 _ C1· 16 PIN HEADER (25 PIN RS232) 2 y. 8 C2+ LINKS us ce C c12 .I. MAX232 1o u 10 ~ C214 TX DATA P01/TOO 11 T11 T10 POO/RD1 12 13 RX DATA R10 R11 GNO §"'"' 0 0 11 RO W7 10 ROWS 9 ROWS 8 ROW4 7 RO W3 8 RO W2 5 ROW1 4 ROWO 2 0 0 3 0 1 08 10 18 07 OF 17 20 KEY2 1F KEY1 1E KEY4 10 KEY3 08 OE 18 05 00 15 04 oc 14 1C 03 0B 13 18 02 OA 12 1A 01 09 11 19 PIN19 U8 -P07 4 8 7 8 9 P05 22 0 TCMP - 250 IRQ -~- 10 P03 PD4 260 t POO 23 _ P01 24 -= :~ -f I I "' ~ 210 TCAP - P04 P03 - w 0 - : 3 (2) s - PB6 18 = PB7 20 ':: : 3 "" 0 9 (S) . b 1(1) ~ 13 (7) 2 8::. : S (3) RP2 10k 0 PB1 PB4 14 _ PBS 18 = 1 0 0.. 15 (B) 11 (6) +SY ... ..."' ...... 6_ PB3 12 RESET 0 PBO PB2 10 = 0 7 (4) +5 3 N J1a YCC V+ 3 4 Y1 Y2 Y3 13= t C8 10 L _ 8 us 74LS139 PA4' +SV 1 18 PA3' - 2 T 1 3 9- 11_ PA7' 19_ , 11 - - PA2' PAS' 1s: PA6' 17 _ PORT A DIP SWITCH ,-- 1: PA1' \\\ 1\\\\ SW1 L PAO' 8 SPI INTERFAC E 5-PIN DIN P02 P01 8x4 KEYPAD (32 KEY) POO 16 15 14 13 12 11 SW2 10 9 \\\ \\\\ 1 2 3 4 5 8 7 8 -,r PORT O DIP SWITCH D ECEMBE R 1992 61 MAL-4: Microcontroller Aid For Learning MCU via an octal data buffer (U8, a 74LS541). The MAL-4 monitor program allows port A to function as an input port under a user program or it can be disabled by switch 6 on DIP SWZ. If the switch is in the ON position, the octal data buffer (U8) is enabled. The loudspeaker is driven by bit 7 of port C via NPN transistor Q3. This is a BC108 (BC548) configured as an emitter follower. The level of signal fed to the transistor is set by volume control pot VRZ. R28 limits the maximum volume level and can be reduced if a higher volume is required. The monitor program generates a series of highs (1) and lows (0) to generate tones from the speaker. Power supply The MAL-4 can be fed from a 12V Hear what the It runs in the family. test panel had to say First Concert VII voted say about Concert II: 'Loudspeaker of The "On audition it didn 't Year'. Now the smaller take long to establish model Concert II that the Jamo was winning hands down something special. in.a group test with 8 The speaker simply other loudspeakers sounded more transin the UK magazine parent and revealing "High Fidelity". than the other speakThe conclusion of ers in the test.... They the test was: "The imaged better.... A speaker that resolved deep, tangible bass the problem was the and crystalline mid dark horse Jamo. Very and treble clarity.... much an unknown Imaging was virtually quantity in the UK, it holographic... " was nothing less than a With 24 years exrevelation when put to The test winner perience having prothe test. It was the one duced more than 10 speaker here with million loudspeakers, genuine grip and grace 2-way bass reflex Jamo is today and, as such, ended up System: Woofer: 1 70mm Polypropylene Europe's preferred the overall winner. " Tweeter: 25mm sofl dome loudspeaker brand. When a Danish Power Handling: 80 watts RMS Timber Finishes: Walnut and Mahogany To experience _ loudspeaker is the RRP: !Timber finish) $1190 pair why Jamo is winning preferred choice in (Black Ltd. Edition) $ 990 pair time and time again, the UK over such brands as B&W, Mission, Heybrook, call into your nearest authorized Jama specialist or contact Scan Castle and Tannoy, it must be of outstanding design, And this is Audio for more information and exactly·what Jamo's Concert II is. the name of your nearest dealer. CONCERT II uamo AWARD WINNING LOUDSPEAKERS SCAN AUDIO, 52 Crown St, Richmond VIC 3121. Phone: (03)429 2199. Fax (03)429 9309 62 SILICON CHIP DC plugpack or a 12V battery. Alternatively, a 9V AC supply can be used. It is full wave rectified by bridge rectifier BRl and filtered by a ZZ00µF electrolytic capacitor (C13). This feeds U9, a 7805 3-terminal regulator to produce a +5V supply which feeds the ICs on the board. This +5V supply also provides the Voo rail for the microcontroller via diode D3. There is provision for a battery backup supply for the RAM. Normally supplied by three AA cells in series (off board), the line feeds the Voo rail via diode D5 and LED 2, when the +5V rail falls. LED 2 is a battery warning indicator. It is a high brightness type and indicates when a current of more than lmA is drawn from the battery. This can occur if the MCU is not shut down before the power is removed. The MCU current under shutdown (STOP) conditions is in the order of a few microamps. Reset circuit The MCU requires its pin 1 to be pulled low for the reset condition to occur. The reset can come from four places: reset switch (S3), pushbutton reset (KEY5), at "power on", or via the input/output plug (PLZ). The reset switch (S3) works simply by pulling the reset pin to 0V. It is intended to be used when the MAL-4 is used as a programmer. Alternatively, the pushbutton reset (KEY5) turns on transistor (QZ) and this pulls the reset pin low. The power-on reset circuit works as follows. Capacitor Cl0 is discharged via diode D4 when the +5V rail falls. When power is applied, ClO is charged via RZZ and the base of transistor QZ. While the capacitor is charging, QZ is switched on and pulls the reset pin low. When Cl0 is fully charged, QZ turns off and the MCU resumes normal operation. Interrupt request The escape or Interrupt ReQuest (IRQ) circuit supplies the MCU with a low (0) on pin 2. The IRQ comes from pushbutton KEY6. This turns on transistor Ql via resistor RZl and pulls pin 2 of the MCU low. · Both the reset and the IRQ circuit prevent the MCU from being reset when there is no power applied to the MAL-4. This is necessary otherwise it could be taken out of the shutdown The assembly of the MAL-4 microcontroller is straightforward as all the parts are mounted on a double-sided PC board with plated-through holes. A kit of parts will be available from the author (details next month). mode (STOP) if the reset or IRQ buttons are pressed and thereby cause excessive battery consumption. Link LNK3 in the IRQ circuit provides the IRQ pin on the MCU with a pull-up voltage of +5V in position 1 or +9V in position 2. Position 1 operates the monitor program while position 2 operates the Boot loading program. Programmer mode If links LNK1 , LNK2 and LNK3 are placed in position 2 and the 8-way DIP switch (DIP SW2) is set correctly, all the MAL-4 peripherals are disabled (display, keypad, monitor EPROM and port A buffer) and the unit becomes a programmer. Note: last month's overview of the MAL-4 may lead readers to believe that the unit can program EPROMs. This is incorrect. At this time, the MAL-4 can only program the EPROM inside the MCU. The steps involved in programming the internal EPROM are set out in the Motorola MC68HC705C8 Technical Summary (BR594/ D). Programming can be done in the following ways: (1). Program and verify internal EPROM from the 8K EPROM (U1) (2). Verify interna"i EPROM contents from 8K EPROM (U1) (3). Secure internal EPROM (4). Load and run program in RAM via RS232 (5). Dump internal EPROM contents via RS232 (6). Run program in RAM When LNK3 is placed in position 2, the MCU is placed into the bootstrap program mode. This mode uses the internal bootstrap ROM. DIP sw 2 selects the programming mode. S1, S2 and S3 are used to switch the power (Vpp) and take the MCU out of reset to enter the programming mode. The 8K EPROM (U1, 2764) is used as the program source. Its data is loaded via port B while the address locations are incremented via ports A and C. Data can be sent to the RAM or from the internal EPROM via the RS232 interface to a PC. LEDs PC5 (LED 5) and PC6 (LED 4) indicate that the program is verified and that the MCU is programming. Next month, we will present the full constructional details for the MAL-4 microcontroller. SC We have over 1,000 different printed circuit boards and screen printed front panels for kitsets from EA, ETI, AEM, HE and Silicon Chip. On special this month only for half normal price! For a complete list of available PCBs and front panels, their date of issue and price, simply send your name, address and stamped self addressed envelope. Note:Duetocopyrightlaws we cannot supply copies of magazine articles. These are available from libraries or the magazine companies (by arrangement) ALL ELECTRONIC COMPONENTS 118-122 Lonsdale St. M elbourne 3000. Ph: (03) 662 3506. Fax:(03)6633822. ~ -~- - - - - - - - - - - - I I ;:.:N.=.am:..=.e_ _ _ _ _ _ _ _ __ I I I -----------I I Address I -----------I I -----------I I Postcode I -----------L ____________ _ .J D E CEMB ER 1992 63 High voltage probes: beware the dangers High voltage probes can be lethal if used incorrectly or for servicing equipment other than that for which they were designed. This coronial report of a recent accident in Victoria highlights the dangers. RECORD OF INVESTIGATION INTO DEATH I, Susan Adele Blashki, Coroner, having investigated the death of ...... . with inquest held at the Coronial Services Centre, South Melbourne on the 12th June, 1992, find that the identity of the deceased was ....... and thatthe death occurred on 25th July, 1991 at the premises of HY-DU-EX, 15 Ormond Avenue, Sunshine from the effects of electrocution in the following circumstances. (1). The deceased, on 25thJuly 1991, was repairing a radio frequency welder at the premises of HY-DU-EX, 15 Ormond Avenue, Sunshine. He was a contractor, employed as an "A" Grade Electrical Mechanic by K. T.V.. Electronics, a small electrical -contracting company. He was the holder of an "A" Grade electrical mechanic's licence and had 28 years experience in this capacity. (2). The welder is designed for the purpose of welding PVC. It is between 15 and 20 years old. On the previous day the deceased had replaced the high voltage transformer and on the day of the accident he had tested two rectifier valves and found them faulty. He had then replaced the valves and was in the process of fine tuning the radio frequency welder. At the time of the accident it is probable that the deceased was testing the high voltage transforrner, us64 SILICON CHIP ing a "Leader High Voltage Probe", LHM - 80 Serial No. 5050061. This probe was found under his body after the accident. The deceased had completely overhauled and rebuilt this radio frequency welder some 3 years prior to this accident. The machine had then operated effectively for a number of years before K.T.V. Electronics was again called and Mr ..... .. attended to service the machine. Editorial Comment This coronial report has been published in full for the information of our readers . While the exact circumstances may not be certain, several cautions can be drawn from the report. (1 ). Use the utmost care when measuring high voltages in big power supplies, such as in microwave ovens or RF welders. They are far more dangerous than the EHT supply in a TV set. (2). Wear rubber soled shoes and rubber gloves while making high voltage measurements. (3). If at all possible; do not work alone. Footnote: the name of the deceased has been omitted to prevent further distress to relatives. He was sufficiently familiar with this particular machine to produce a set of technical, electrical drawings on it. (3). It is probable that the accident was caused either by the earth lead of the probe dislodging and coming into contact with high voltage, or the deceased may have been attempting to put the earth clip on the earth centre tap of the 6000 volt secondary connections and inadvertently put the clip on one of the positive terminals. It appears that the electrical current may have passed up the earth/ return lead and exited through the potentiometer adjustment screw access hole to the hand of the deceased, thereby delivering a high voltage shock to him. This shock would have thrown him back when he then struck his head on the cutting ·board of an adjoining click press and fell to the floor. No other person was present at the time this incident occurred, but both the proprietor and another employee . at the building at the time heard a loud bang and discovered the deceased with scorch marks on his right fingers and marks on the back of his head. (4). The deceased, whilst working at these premises the previous day, had complained of being faint and requested a chair. He had also complained to members of his family that he was very cold on the eve·n ing of the · 24th July, 1991 and to the factory manager at HY-DU-EX on 25th July, 1991 that his legs were very cold just prior to th!:) accident. About 6-8 months previously the deceased had collapsed whilst at work and been absent for approximately three months, but was at the time of the accident considered by his doctor to be fit for normal duties. (5). The general area of HY-DU-EX measures 31 metres long by 9.5 metres wide. It was constructed by a steel frame with corrugated iron walls and roof sheets. The area where the deceased was located had a concrete floor, and there was a section of what appeared to be rubber conveyor belting covering the concrete in the form of a floor mat. The temperature on the 25th July, 1991 at approximately 2pm was between 7°C and 10°C, with even lower temperatures being recorded earlier that morning. (6). At the time the deceased was working on this machine there were a number of tools scattered around including screwdrivers, pliers and electrical type tools, but the only one considered to be dangerous was the high voltage probe which was found to have recent burn marks on the handle. It is probable that the electric shock originated· from this piece of equipment as the burn mark on the handle matched the burn marks on the hand of the deceased. The Leader high voltage meter probe, model LHM 80 would have been used to check voltage within the machine when it was operating. It was manufactured by Leader Electronics Corporation, Japan, in approximately May, 1975. It is designed not for checking voltage on an RF welder, but for checking DC voltage of television sets. This model did not have any insulating cover fitted over the potentiometer adjustment screw, although since August 1985 this model has been modified to include an insulating cover. Production of the modified unit was discontinued in April, 1991. (7). It is probable that a person holding the lead of a high voltage probe while kneeling or sitting on the concrete floor and the flexible lead or alligator clip coming into contact with a high voltage within the machine could receive an electric shock sufficient to cause death. (8). I find that based on a reasonable belief, for reasons unexplained, the deceased has incorrectly used the EHT probe thereby receiving an electric shock of sufficient intensity to cause death. (9). I further find that whilst the external temperatures were cold, and that the factory may also have been cold, that there is no evidence to suggest that this was a factor contributing to the cause of death, and that no other person has contributed to the cause of death. Care required with high voltage probes I am writing to ask for your assistance in alerting your readers to the potential danger associated with high voltage probes as used in testing television receivers, transmitters and other equipment requiring high voltage measurements. The result of a recent coronial inquest in this State has highlighted the dangers associated with the use of such test equipment. The victim in this incident was a qualified "A Grade" licensed electrical mechanic who was testing a radio frequency welding machine. He had extensive experience in testing and repairing this type of equipment. This incident has highlighted the need to ensure that: tools and equipment are kept in good working condition; equipment is used within the manufacturers' guidelines; the earth connection is intact and operative; COMMENTS AND RECOMMENDATIONS The Leader High Voltage Probe LHM 80 is designed and manufactured by Leader Electronics Corporation, Japan and is marketed in Australia by AWA Distribution. It i.s designed for measuring high voltage (+25,000 volts) in colour TV receivers by qualified TV technicians and is safe to do so. Whilst the probe can be used for other purposes, such as measuring other high voltage sources, qualified and experienced technicians using this equipment should be aware of the possible dangers involving the measurement of dangerous high voltages · as these high voltages can result in the death of the operator if used incorrectly. The dangers to the operator could be measuring a negative supply exceeding 1,000 volts whereby electrocution could occur through the trimpot hole, or where the "earth" clip falls off, where a minor electric shock could occur but which could result in a secondary injury occurring as a result of the operator withdrawing their hand. This EHT probe and other similar types are widely used throughout the TV serving industry for the checking of EHT in TV receivers for being ei- extra care is taken when working in the vicinity of live electrical equipment. There has been an increase in the occurrence of electrical fatalities and serious electrical accidents involving electrical workers including engineers, technicians and mechanics in the past year. We must all take greater care when working with any electrical equipment. I request your assistance in warning your readers, many of whom are involved with the testing, repair, manufacture and design of electrical equipment, that caution should always be exercised when working on live equipment. R.N. Clark, Chief Electrical Inspector, State Electricity Commission, Victoria. ther under or over voltage. They are quite safe to use, and the Leader probe falls into this category when used correctly. It is recommended that all industries which use an EHT probe to measure high voltage be. advised of the dangers of using an EHT probe. In particular, attention is drawn to a new service industry developing in microwave ovens. The high voltage in a microwave oven is several thousand volts, and. is negative. Its existence can be measured with an EHT probe used inversely which may prove fatal if the insulation on the probe breaks down, either through the probe handle if dirty or cracked, or through trimpot holes, or the negative connecting lead if its insulation is damaged. It is noted that a document has already been prepared by ·the Occupational Health and Safety Authority alerting persons who use high voltage meter probes of the dangers associated with their use. It is hoped that distribution of this information to po- · tential users will reduce the likelihood of a further tragedy such as this in the future. S.A. Blashki, Coroner DECEMBER 1992 65 A 2kW 24V/240VAC sinewave inverter; Pt.3 In this third article on the 2kW inverter, we present the H-pack output drive circuit which converts the 365V DC rail into 240VAC. We also describe the pulse drive circuit which enables the H-pack to produce a sinewave output. By JOHN CLARKE Last month, we described the heavy duty DC-to-DC converter circuitry which steps up 24V DC to 365V DC and we emphasised the design problems in handling currents in excess of 100 amps. But having obtained the high DC voltage, it must be converted to a 50Hz 240VAC sinewave and this presented more onerous problems 66 S1LJCON CHIP than the DC-DC conversion. Our initial approach to this part of the circuit was to use heavy duty Mosfets but this proved to be a dismal failure. These devices just could not do the job and so we turned to a hybrid device, the insulated gate bipolar transistor. These devices are available in higher current and volt- age ratings than Mosfets and enable us to design a H-pack output drive circuit which requires just four devices. This means that there is no need for paralleled devices and hence problems of uneven current sharing are eliminated. The circuit for the H-pack drive is show:n in Fig.10. This uses eight ICs (IC6-IC13), three transformers, four insulated gate bipolar transistors (IGBTs), four soft recovery diodes and associated passive components. Before we dive into the circuit description, let's just refresh our memory on the overall concept of this sinewave inverter. This is best done by referring to the block diagram ofFig.3 MOSFET DRIVERS i ANO CONTROLLER + 24V BATTERY STEP-UP TRANSFORMER x18 HIGH VOLTAGE FULLWAVE RECTIFIER HIG~ VOLTAGE LTER CAPACITOR +365V ISOLATED VOLTAGE FEEDBACK A A SWITCH 1 SWITCH 2 8 8 L2 SWITCHMODE SINEWAVE GENERATOR X C -c D SWITCH 3 D SWITCH 4 DV Fig.3: repeated from the first article, this block diagram illustrates the basic arrangement of the sinewave generator & H-pack output drive circuits for the 2kW inverter. Switches 1-4 are equivalent to the insulated gate bipolar transistors (Q17-Q20) shown in Fig.10. which we have reproduced from the first article. We won't go through the description of the block diagram again other than to point out that the H-pack circuit consists of semiconductor switches 1-4. These are fed with pulse signals from the switchmode sinewave generator which allow the circuit to produce a 50Hz sinewave, after suitable filtering. Switches 1-4 in Fig.3 are the insulated gate bipolar transistors we have already referred to. Switch 1 is Ql 7 on Fig.10, switch 2 is Q18, switch 3 is Q19 and switch 4 is QZ0. These IGBTs are Siemens BUP304 devices which have a collector-emitter voltage rating of 1000V and a continuous collector current rating of 35A. They can be pulsed at currents of up to 50A and because they have insulated gates, they can be driven in the same manner as Mosfets. Hence, each IGBT gate is driven by six paralleled 4049 CMOS inverters. So Q17 is driven by IC7, Q18 by IC9, Q19 by IC11 and QZ0 by IC13. The paralleled inverter outputs provide sufficient drive to charge and discharge the Z000pE gate capacitance which must be done to switch the IGBTs on and off. Zener diodes ZD8, ZD10, ZD12 and ZD13 protect the gates of the IGBTs against overdrive. Each 4049 hex inverter IC is driven by a fast optocoupler with an isolation rating of 5300V and a switching response time of about 0.5µs. The LED in each optocoupler is driven by the switching sinewave generator circuit yet to be described. When the LED is turned on, the transistor in the optocoupler turns on and pulls the inverter inputs low. This pulls the respective IGBT gate high and-turns it on. Conversely, when the LED is off, the IGBT is off. Isolated supply lines Turning the IGBTs on and off requires a lot more than just having a paralleled hex buffer to drive each gate, however. For the two top transistors in the H-pack (Ql 7 and Q18), each 4049 buffer requires its own isolated 15V supply. Similarly, for the other two transistors in the H-pack, the 4049s require a common but still isolated 15V supply. There are several reasons why the 15V supply used for the drive circuitry in the DC-to-DC inverter cannot be used. The first reason is that the 0V line of the 365V supply cannot be tied to the 0V line from the 24V battery. This MAINS GPO is necessary because both the . high voltage DC and the 240VAC output must be completely isolated from the battery input circuits. This is done for safety reasons and also to prevent any feedback process which might upset the circuit operation. For the top two transistors in the Hpack, there are much more compelling reasons for having the isolated supply lines for the buffers. When Ql 7 or Q18 turns on, its collectoremitter voltage drops to a very low value and so its emitter jumps to almost +365V. So when Ql 7 turns on, its emitter jumps to +365V and so does the rest of the circuitry tied to that emitter. Hence, pin 8 of IC7 and pin 5 of IC8 is also pulled to +365V. The sµme process also applies to Q18, IC9 and IC8. This means that three isolated 15V supplies are mandatory for the circuit to work. The isolated supply lines are provided by three small transformers : TZ, T3 and T4. These are driven by a common high-frequency driver circuit which operates at about 1MHz. We'll describe how this works later in the article. The secondary outputs of TZ, T3 and T4 are rectified using small signal diodes D7, D8 and D9 and the DC DECEMBER 1992 67 +365VO-------------------------------------+---------D7 1N4148 4.7k 106 SFH6136 • 1 50VW LL - 017 BUP304 8 K D10 BYP102 J A ~~~ J A G B 1W H (1) X ~ H GOE K A D9 1N4148 (3) 4.7k 1010 SFH8138 ZD11 15V 1W 1 + 50VW LL - 8 K 8 J SIOV3 S14K275 019 BUP304 1D A 5 ZD12 18V 1W K J SIOV4 S14K275 HIGH VOLTAGE SWITCHES AND FILTER is smoothed with a lOµF capacitor. The supplies are each regulated using a series resistor and a 15V zener diode (ZD7, ZD9 and ZD11 respectively), and are each bypassed with a lµF capacitor. While these three transformers are very small, the 1MHz operating frequency means that they are very efficient and quite adequate for supply68 SJLICON CHIP ing the gate current requirements of the IGBTs. IGBT voltage protection You might think that because the IGBTs have a 1000V rating, they would be rugged enough to withstand anything that the circuit could throw at them. Unfortunately, that is not true and they do require protection both for themselves and their insulating washers. Since these IGBTs do not have internal reverse diodes, as do power Mosfets, we have connected a BYP102 fast recovery diode across each one. These are D10, D11, D12 and D13. When each IGBT is switched off, its inductive load generates a very sharp voltage transient which raises the D8 1N4148 +365V 4.7k E IC8 SFH6136 ZD9 15V 1W LL - 018 BUP304 D11 BYP102 6 J ZD10 18V 1W 5 C SIOVS S14K275 1 sovw SIOVI S14K275 J D (2) 0.75mH 10A L3 0.75mH 10A L4 y FS 10A 15A Elli FILTER DELTA 10DRCG5 GPO OUTPUT 240V SOHz SINE +385V CHASSIS (4) 4.7k IC12 SFH6136 1 + S00VAC- SIOV7 S14K275 1 + 50VW LL 020 BUP304 K D13 BYP102 ). A ZD13 18V 1W II emitter above the collector in the case of Ql 7 and Q18, or pulls the collector negative with respective to the emitter in the case of Ql 9 and Q20. During switch-off, the diodes conduct and clamp the emitter of each IGBT to its collector and hence prevent reverse voltage punch-through. The BYP102 diodes are rated at lO00PIV and 50A peak, and have a SIOVI S14K275 J N response time of 130ns. Even with diode clamping, the large voltage transients produced at the instant the IGBTs switch off can cause breakdown of the insulating washers. This problem has been controlled in two ways. First, a lµF 500VAC capacitor is connected across the 365V supply rail close to the IGBTs. This effectively counteracts much of the Fig.10: the H-pack output drive circuit is based on insulated gate bipolar transistors Q17-Q20. These in turn are driven by a sinewave generator circuit (see Fig.11) via optocouplers IC6, IC8, ICtO & IC12 & hex buffer stages IC7, IC9, IC11 & 1Ct3. The optocouplers serve to isolate the highvoltage output stage from the 24V DC supply. Transformers T2-T4 & diodes D7-D9 provide isolated DC supply rails for the optocouplers & 4049 hex buffers DECEMBER 1992 69 n :r: :a z n 0 r=: C/l Q "-l I +5V 100k! 0.1 • I 2 IC14 7555 ": ": ........;t I 220pfj +5V 5 t 16 4 I ": 14 8 -·- ": 16VW 10 I 1 I I 10 3 10 ": • +5V 4 8 u n ": 14 8 CLR 5 COUNT UP 16 4 B A po~• IC15e R I ~n III 2 A3 7 2 ae E GIil A2 8 3 QA E ~,,-• I 711o.. IC15d 1 IC19 74HC193 11 A4 6 6 QC 9 AS 5 7 0D CARRY 15 10 B IGO ~ IC23 NIIC27C84N OTP-ROIi A6 4 QA AS 25 6 QC r 05 A7 3 2 QB 9 A9 24 7 QD CARRY 15 10 0.1+ I I I I I I 3 21 3 1 A11 I 23 2 ae VPP PGII A12 VCC 2 6 IC17dr. 11 0D 27 I; I .c- 2200 2200 2200 ~~~~ .... + ": 12 ": -~~~- r =\\Y, 021 ": o.1I IC17e 0.1+ ~8 15 10 QC IC21 74HC193 11 IC22d~ A10 IC22■ Y. 14 CLR QA I l I I 8 16 I I. I I I I 19 5 COUNT UP I IC17d 3 ..... - 4 ~7 08 12 ": 0.1 ! +5V:t'Q I Y. CLR 1 IC20 74HC193 11 IC22c 74HC08 10 16 4 5 COUNT UP EOc VIEWED FROM BELOW 12 ": ... o.1I LOW VOLTAGE TRANSFORMER DRIVERS AND SWITCHING SINEWAVE GENERATOR ~ 12 ": ... o.1I I I '.IC181 .... , I £""'°-c ecr-o A1 9 7 QD IC15b 1 1, AO IC15c + I 11 I CARRY 6 QC rJ 10 I 15 10 9 a IC18 74HC193 11 QA I IN~OUT REG2 Allo.. 4049 0.1+ .I. 0.1! 0.1 ! I. I COUNT UP CLR M~I • I I -: 22pf I 0.1+ 2.2ki 10 .&,. 25VW+ sw~~6~Eo 0 22pf+ ": 1011 ~- X1 3.2768MHz . • N ~ ~K t :~ supply lead inductance which causes the sudden voltage transient. Second, we have connected Metal Oxide Varistors (MOVs) across each IGBT to clamp the voltage to an acceptable level. Each IGBT has two SIOV S14K275 varistors in series, which effectively gives voltage clamping at about 780V. The H1 resistor in series with each pair of MOVs limits the breakdown current through the varistors to a safe value. Output filter The difference between the pulse ◄ Fig.11 (left): the sinewave generator circuit uses crystal oscillator stage IC17a to drive cascaded 4-bit binary counters IC18-IC21. These in turn drive the address inputs ofIC23, an OTPROM which contains the sinewave code. Its outputs, at D5 & D6, then produce pulse signals to drive the optocouplers in the H-pack output stage via transistors Q21-Q24. IC14 & its associated inverter stages provide the low voltage drive to transformers T2-T4. This close-up view shows the H-pack drive circuitry for the inverter, with the outputs from the sinewave generator circuit at bottom right. The four switching transistors (IGBTs) are bolted to the chassis on either side of the board, along with their BYP102 protection diodes. width modulated waveform at point X (ie, the junction of Q17 and Q19) and the PWM waveform at point Y (the junction of Q18 and Q20) becomes the output waveform after filtering. This filtering is provided by inductors L3 and L4 and the 25µF 3 70VAC capacitor connected between points X and Y. While the switching rate of the IGBTs is 4kHz, the filter cutoff frequency is set to about 820Hz to produce a smooth sinewave as depicted in the photographs published last month. However, this filtering is not sufficient to avoid interference to radio and TV reception. Hence, further filtering is provided by a commercial EMI filter rated for load currents of up to 10 amps. Sinewave generator That concludes the description of H-pack circuit ofFig.10. We now need to refer to the diagram ofFig.11 which shows the sinewave generator and high frequency transformer drivers. The latter provide the isolated 15V supplies via transformers T2, T3 and T4 . The transformer driver circuitry comprises IC14, IC15 and IC16. IC14 is a CMOS 555 timer which is connected to produce a square wave with a duty cycle of 50%. Unlike the usual 555 circuit configuration, the output at pin 3 charges and discharges the 220pF capacitor at pin 2 and pin 6 via a 2.2kQ resistor. At switch-on, pin 3 is high and the 220pF capacitor charges via the 2.2kQ resistor until the voltage across it reaches 66% of the 15V supply. Pin 3 then switches low and discharges the 220pF capacitor via the 2.2kQ resistor until thEp voltage reaches 33% of the 15V supply. This causes pin 3 to again go high and so the cycle repeats. The frequency of the square wave at pin 3 is about 1MHz. The output of IC14 is buffered by IC15a, a 4049 inverter. This in turn drives inverters IC15b, IC15c and IC16a. IC15b and IC15c are connected DECEMBER 1992 71 The sinewave generator board carries the low-voltage transformer drive circuitry & the NMC27C64N OTPROM. This board is mounted on the bottom of the case & its outputs connected to the H-pack output board via flying leads. in parallel to drive IC15d, IC15e and IC15f. IC16a drives paralleled inverters IC16b and IC16c which in turn drive IC16d, IC16e and IC16f. The buffered outputs from these stages then drive the primary windings of transformers T2, T3 and T4 on the H-pack output PC board. . The circuitry for the sinewave generator includes four 4-bit synchronous counters (IC18-IC21), an BK x 8 OTPROM (see below), a 4049 hex inverter (IC17), a quad 2-input AND gate (IC22) and four transistors (Q21-Q24). CMOS inverter IC17a is connected as a crystal oscillator operating at 3.2768MHz. Its output signal appears at pin 8 and is applied to the clock input (pin 5) of binary counter IC18. The four binary counters (IC18IC21) are cascaded together to divide the 3.2768MHz signal. These counters are synchronous types which means that their outputs at QA, QB, QC and QD all change together with the clock input. IC23 is an BK x 8 One Time Programmable Read Only Memory (OTPROM). The only practical difference between an OTPROM and an EPROM is that an OTPROM can only be programmed once while an EPROM 72 SILICON CHIP can usually be programmed and erased many times. Since the OTPROM does not have a window in the package, it is quite a bit cheaper. IC23 contains the code for one half of a complete sinewave. It has 13 address lines and these are driven by the Q outputs of the binary counters. Two of its data lines, D5 and D6 at pins 16 and 17, then produce the necessary pulse signals to drive the Hpack output stages. Since the frequency fed to the AO input is 409.6kHz (3.2768MHz divided by 8), the frequency fed to the A12 input is 100Hz (409.6kHz divided by 4096) and this provides exactly half the period for a 50Hz sinewave. Because IC23 counts up from 0 when all its address inputs are low (0) to 8192 when all its address inputs are high (1), the OTPROM produces a high and low signal sequence at its D5 and D6 outputs. IC17b inverts the QA output ofIC18 and drives the G-bar input to IC23, pin 22. When the G-bar input is low, the data outputs (D5 and D6) of IC23 have a low impedance. Conversely, when the G-bar input is high, the data outputs are in a high impedance state. When the address lines of IC23 change to the next count, there is a short time when the data outputs are invalid since the OTPROM has a finite access time of 250ns. To cope with this problem, the G-bar input is held high (QA ofIC18 is low) and the data outputs are in a high impedance state for 305ns between each valid code. It may appear to be bad design to have the data outputs at D5 and D6 in a high impedance state for this brief time interval. After all, these outputs are driving the CMOS inputs of quad AND gate IC22. In practice though, it is not a problem since the input capacitance of the AND gates acts to maintain the last valid code. When the data outputs return to their low impedance state, they drive the CMOS inputs in the normal way. AND gates IC22a and IC22d each have one input connected to the QD output of counter IC21. This output is also inverted by IC17e to drive one input of AND gates IC22c and IC22b. Since QD is a 50Hz square wave, it is high for 10ms and low for 10ms. Thus, QD effectively controls the AND gate package and determines which of the four driver transistors (Q21-Q24) receive the switching signal from the OTPROM. IC22a drives transistor Q23 which drives optocoupler IC10 and transistor Q19 on the H-pack board. Similarly, IC22b drives transistor Q24 and this in turn drives optocoupler IC12 and Q20. The D6 output of IC23 therefore controls the lower switches of the Hpack. Similarly, the D5 output ofIC23 controls the upper switches of the Hpack. These separate outputs allow dead time to be included in the sinewave generation coding between opposing switches. For example there is dead time between the '1' switch turning off and the '3' switch turning on. Power supply Power for the circuit is derived via REG2 which regulates the 24V supply to provide a +5V rail. The series 150Q resistor limits the current through ZD14 which is included to protect the input of the regulator. The 10µF capacitors at the input and output of REG2 provide supply decoupling. That concludes the circuit description of the 24V/240VAC sinewave inverter. Next month, we will describe the construction of the DC-to-DC converter board. 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This atlas, almanac and world fact book in one, gives you instant access to over 240 fully detailed, EGNVGA colour maps and a huge database of international information. all for IBM (also Mac where shown) ORDER PRICE Chess with sound and animation D $90 Microsofts musical journey (also MAC) D $135 9 Bibles 3000 Sermons, 6 dictionaries D $90 Classic story - music and sound effects D $90 A classic game - now a classic CD D $90 - RI MICROSOFT Iii BOOKSHELF ,, Page Total $160 $160 $860 $8.00 TOTAL I enclose che,que, money order for $....... ........... ... or please charge my aedt card (below) Mr/Mrs/Ms (please print) . .. . .. .. .. .. .. .. . .. . .. .. .. .. .. ................ Address.................. .... .................................................. .............................. ................. Postcode ............. ........ Phone ..................................... Fax no ......................... . D BANKCARD D MASTERCARD D VISA Card Number: I I I I I II I I I .1 I I I I I I I I I I I I I I I I I I L Expiry date.................................................................... Cardholders Signature .........•............................. ........... 1 ■t PELHAM PTY LTD Floor, 100 Y - Road, Pennant HIii■ 2120 Ph (02l 980 . . . . F- (02) NO U91 See• II Boolh 141, HOME COMPUlER SHOW, Melbourne 1I I VINTAGE RADIO By JOHN HILL Preventing trouble & making odd repairs to old receivers One problem that constantly confronts vintage radio restorers is the lack of suitable spare parts. Some valve radios are now 60 years old or more & so the vintage radio repairman must be prepared to improvise. Those rotten little furry rodents (commonly known as mice) can do more damage to an old radio set than one could possibly imagine. Mo:;;t radio chassis have a few unused holes which give mice ready access to the underside where most of the vulnerable parts are housed. Any radio that has been stored in an outside shed will, most likely, have been home to mice at some stage. I recently inspected some old radios that came from a retired radioTV salesman. They were his trade-ins over a 40-year period and had been stored in "dry" sheds. One of these sheds consisted of a "U" shaped formation of old refrigerators (also tradeins) with sheets of galvanised iron on top for a roof. Many of these receivers were in a terrible condition, as one could well Rodent damage to old sets can be quite extensive, as this photograph clearly shows. The component at left is a wel~-chewed capacitor, while at right is the remnants of a chewed aerial coil. Careful storage of old receivers can prevent this type ofdamage. 74 SILICON CHIP imagine, but mice weren't the only rodents that called these sets home. No mouse could have caused that much damage. Rats had torn the wiring to shreds. Power transformers, chokes and coils had had the windings ripped out of them -they were just about total writeoffs as far as restoration was concerned. Any collector who stores his sets in outside sheds would be well advised to take a few precautions against rats and mice. A few traps and a packet of "Ratsack" are cheap insurance. Mice cause two major problems .in old radios: they nibble the wax coated components and their urine is highly corrosive. There is nothing quite like resoldering urine soaked joints - the stench is terrible! One common mouse problem is chewed paper capacitors. Once those sharp little teeth start chomping into the foil layers, they short circuit the capacitor. It is not uncommon to find all of the capacitors ruined in a mouse infested receiver. Capacitors are easily replaced and in most vintage radio restorations they should be replaced whether chewed or not. However, when little teeth start sampling aerial and oscillator coils, plus other tasty morsels, the damage is not so easily rectified. I recently had a mouse damaged oscillator coil to contend with and, rather than look for a suitable replacement, I decided to have a go at repairing it. In this particular instance, urine had turned one of the coil leads green and the electrical continuity in that coil had vanished. If the corroded wire had come from the outside of the coil winding it wouldn't have been difficult to pick up the outer strand of wire and rejoin it to the connection tag at the base of the coil former. But no. This mouse had to do it on the inside connection - didn't he! This meant unwinding the whole coil so that the inside lead could be reconnected. As it turned out, the job was surprisingly easy and the repaired oscillator coil worked as good as new. My approach was to first unwind the faulty winding. I then made and attached two cardboard disks to the coil former, spaced the same distance apart as the width of the original coil. The original wire was then wound back on, with each end connected to the appropriate tags at the base of the coil former. No doubt it would have been a good idea to have counted the turns but, because I was interrupted half way through the operation, I forgot where I was up to. The less scientific approach seemed the only alternative. The fact of the matter is that the oscillator coil worked perfectly after the repair was completed. Because the coil had an adjustable iron core slug, it was easy to compensate for a few turns discrepancy in the winding. I have performed similar repairs on intermediate frequency transformers and, once again, they worked quite satisfactorily. A few turns one way or the other makes little difference because IF transformers also have ad- Old radio valves, particularly those from the 1920s and 1930s, often have problems with loose bases & "crook" solder joints. Resoldering the base pin connections often restores an otherwise useless valve to full working order. justments, in the form of trimmer capacitors or iron cores, which can make up the difference providing it is not too great. However, one should not approach these problems in a totally haphazard way. If the inductance of the replaced winding is somewhere near that of the original winding, then the repair will be successful. If the change in inductance is beyond the range of the adjustments, then the repair will not be successful. So while I have done a few tricky repairs of this nature and have got away with it, perhaps there This oscillator coil was repaired by undoing the top winding, re-attaching a corroded lead and then rewinding the coil between two cardboard washers. The re~!'-d was completely successful. is an element of luck involved too. A simple repair like rewinding an oscillator coil is usually better than replacing the damaged component with one that may not be an identical unit. Can you tell the difference between various oscillator coils simply by looking at them? Unusual repairs Now let's move on to another type of repair, one that made a lot of junk quite serviceable, not to mention valuable. I have a good arrangement with Unfortunately, there was no reprieve for this old triode, as one of the lead-out wires had broken off inside the glass stem. Corrosion of the wire due to damp storage conditions was the probable cause. DECEMBER 1992 75 They might look like new but these old valves were salvaged in poor condition from the local tip. They are, from left: a 27, a 45 & a 26. None of these valves showed any signs of life until their base pin connections were resoldered. Base pin connections are always suspect and many were never soldered properly at the factory. Cleanliness (bright shiny metal) is an essential factor when resoldering old connections. young Peter, the lad next door. He spends some of his time scrounging at the local tip (you can do that when you live in a country town) and anything of interest in the way of old radios, etc, he brings home and sells to me for whatever I think is a fair price. Peter also strips high voltage polyester capacitors from old valve TV sets and keeps me fairly well supplied. Over a period of a couple of years, he has extracted quite a few hundred dollars from my wallet. 76 SILICON CHIP Pete's latest find at the tip was a box of old valves and they were passed over the fence for inspection. There were about 40 valves in the box, the most modern one being an old 47 output pentode. The others consisted of 4V an.d 6V battery triodes (B406, A609, etc), plus a number of early AC valves (24, 26, 27, 35, 45, etc). Unfortunately the valves appeared to have been stored for many years in a shed ·with a leaky roof. As a result, their outward appearance was most uninspiring. Most of these valves seemed to be totally dead but a few of them tested quite OK. I gained the impression that they may have been put aside because they were in "good" condition, even though that may have been 50 years ago when the roof didn't leak. So I investigated them more closely. Age and moisture can have a strange effect on a soldered connection. The solder loses its bonding (probably due to electrolysis) and although it looks reasonable on the outside, there is little or no electrical contact between the parts the solder is supposedly joining. No doubt there is some highly scientific metallurgical name to describe this ageing process but "cruddy solder joint" will have to suffice in its absence. Socket connections I also understand that the lead-out wires used in valves presented· their own soldering problem and that faulty base connections were not uncommon in new valves. These leads are not simple copper wire as they might appear, but a special alloy designed to have a similar temperature coefficient to glass, so as to preserve the vacuum seal at varying temperatures. This soldering problem was evident with these old valves and the base pin connections of one in particular looked very suspect indeed. When the solder was melted out of the pin connections, there was absolutely no tinning on either the wire or the pin. Both parts were dull and dirty looking. Because the valve had a loose base, it was removed so that the internal . wiring could be inspected. Th.e connecting wires were tarnished but otherwise OK. The ends of the wires were cleaned and retinned. Likewise the ends of the base pins. The base was then cleaned and refitted to the valve and the pin connections resoldered. Super glue was used to secure the base to the glass envelope of the valve. The end result was most pleasing - a B406 in excellent working order! It took many hours to check out those grubby old valves and most of them responded favourably to these repairs. Even the valves that tested OK were resoldered because, although they were working, some of those pin connections looked highly suspect. KALEX The UV People ETCH TANKS • Bubble Etch • Circulating LIGHT BOXES • Portuvee 4 • Portuvee 6 e Dual Level TRIMMER e ldeal PCB DRILL • Toyo HiSpeed MATERIALS This speaker wiring was chewed through by a rat. Storing old radios in a safe place, away from rodents, can save a lot of headaches. Rats are very destructive animals. What I have suggested here is nothing new or revolutionary. It is something I have done many times in the past, with mixed degrees of success. I never discard a valve without trying to salvage it first. Quite often, a badly soldered pin connection (usually a heater pin) is all that prevents the valve from working. I have even found it necessary to resolder the pin connections on new valves. By "new", I mean unused the valve can actually be 40-50 years old. The Stromberg-Carlson Most of my vintage radio writings are directed at readers of limited experience and the next item illustrates the trouble some people get into when they do not know what they are doing. The saying, "a little knowledge is a dangerous thing," does have an element of truth in it. I was asked by a new radio collector to have a look at his 1939 Stromberg-Carlson, a console model with pushbutton tuning. He had bought it at a country auction for the bargain price of $6.00 and wanted to have it restored so that he could use it. Now this guy didn't know what he had bought. The set was a 6V vibrator model and it no longer had tlie two alligator clips attached to the power cord. What did he do? That's right! He put a 3-pin plug on the end of the tattered cord and plugged it into the 240V mains! Despite the fact that the set had a fuse, the result was five burnt-out valves and possibly other damage that · I did not bother to check out. To quote his own words: "it smoked a bit at the time , so it's only fair that I tell you what happened!" Another small problem with this set was the tuning mechanism. The drive from the control knob to the tuning capacitor shaft went via a worm and wormwheel reduction to a friction drive mounted on the capacitor shaft. The fibre wormwheel was all chopped out and the friction drive (a rubber-tyred affair) was perished and useless. What was wrong with using a simple dial cord and a couple of idler pulleys? The somewhat disheartened radio collector qeparted with his wreckage. His farewell comment was, "I have learnt quite a lot for $6.00"! He was lucky: his lesson could have cost him his life. A colleague reports a similar incident. The set was a 6V valve-type car radio that had been imported from the US from an era when American cars used 6V electrical systems. It was connected to a 12V battery and it too smoked a bit. The vibrator power supply components took quite a beating and he is still trying to salvage it. So be warned about such things. Take a close look first before doing something that you may regret later on. If you have any doubts , ask someone who knows! SC • PC Board: Riston, Dynachem e 3M Label/Panel Stock • Dynamark: Metal, Plastic AUSTRALIA'S NO.1 STOCKIST * * I VISA I 40 Wallis Ave, East Ivanhoe 3079. Phone (03) 497 3422, Fax (03) 499 2381 Old Reprinted Electrical Books Build a 40,000 Volt Induction Coil ............ $9 Short Wave Radio Manual (1930) ........ $23 High Power Wireless Equipment (1911) $16 High Frequency Apparatus (1916) ........ $19 Build Short Wave Receivers (1932) ...... $13 Vision By Radio (1925) ......................... $16 1936 Radio Data Book .......................... $12 How to Become a Radio Amateur (1930) $6 All About Aerials ....................................... $5 Television (1938) ...................................... $5 Shortwave Coil Data Book (1937) ........... $5 1928 Radio Trouble-Shooting ............... $24 101 Short Wave Hook-Ups (1935) ........ $14 Vacuum Tubes in Wireless's ................. $21 Construction of Induction Coil ............... $21 Tesla: Man Out of Time (biography) ...... $22 Tesla Said, articles by Tesla 292pp ....... $74 My Inventions, by Nikola Tesla 111pp ... $27 Dr. Nikola Tesla - Complete Patents ..... $93 Tesla Coil Secrets ................................. $13 How to Build a Solar Cell That Works ...... $9 1914 Catalog Electro Importing Co ....... $14 Electric Arc Furnaces ............................... $6 Experimental Television ........................ $25 Allow 15 weeks for delivery of some items. Payment can be made by cheque made out to Plough Book Sales, PO Box 14, Belmont, Vic. 3216. Phone (052) 66 1262. DECEMBER 1992 77 ,.•• r-.t ,..... ,~.., '-•.... ,~., '-•.... ,....., ,.~. ,....., ,.~. t ) ---- ~• DISK STORAGE BOXES t.. ? ~• ~ 31/2 Memorex disk box holds 10 disks C12840............$3.95 31/2 Eclipse disk box holds 40 disks * No lock C16040 ............$6.95 3 1/2 Disk box li.:lds 50 disks • Locks & Keys C16035..........$14.95 3 1/2 Eclipse disk box holds 90 disks • Locks & Keys C16046..........$10.95 3 1/2 disk box holds 100 disks • Locks & Keys C16038...........$16.95 3 1/2 disk box holds 140 disks *L k & K C16039 $21 95 oc s eys ...........w · . ~ Ar lllf' .. ..-,:- ~ ? .. ~ .,.... ~ lllf' .,!. 51/4 Memorex disk box holds . 10 disks C16030.............$3.50 5 1/4 Disk box Holds 60 Disks * Lock & Keys C16025............$14.95 5 1/4 Eclipse disk box holds 100 disks ...., ~ ? t.. ; ~~~::box ~ P:!~6t;;!:!P □· ·· - ~~~~~c·.;~.-~ii;··$9.95 l_ ~ -" P10651 ....................$12.95 . 16 Pin IC test clip ' - P10852....................$14.95 18 Pin IC test clip ~ P10653 ....................$14.95 ~ - < 20 Pin IC test clip o ~ P10655....................$20.95 --._________ ~ 24 Pin IC test clip ~ P10656....................$22.95 28 Pin IC test clip P10657....................$26.95 36 p· IC t t I' P10~~8 ..... .. ~.'.~ ..$34.95 40 Pin IC test clip 39 95 $ • p $ 6410660 p· l............. i._..... 44 .95 t Pl0 ' n C teS c lp $ 661.................... 49 .95 ~~ :~':!:~~c·;~~.·~·11·~. .;1~6:~~0·dl;k;·..$6.95 TORROID TRANSFORMERS 2 X 12V 160VA :!s,1:i..1·sovA··············$69.95 M16710..........................$69.95 2 X 25 160VA ~ M16730.......................... $69.95 2 X 3ov 160VA €) . 9 95 :!s;:i·160VA ..............$s . M1674o..........................s69 .95 2 X 12V 300VA M16750 ..........................$87.50 2 X 1BV 300VA M16760 .......................... $87.50 2 X 25 v 3oovA M,s77 o..........................$B7.5o ...... ......... $87.50 2 X 35V 300VA 75 :~s:ii300VA...............$B . o M16800 $87 50 2 X 45VioovA.............. . M16810 ..........................$87.50 2 X 45V 225VA ~~6~~~·~·~·~·~~ .. .,J//r• ~~!::i~:;:i~~=:t~'.~~.~.~;1d~~~s 5 1/4 Disk box holds 140 disks • Lock & Keys C16028 ..............$19.95 ~. KEYBOARD • t.,. .ANTI-STA TIC MATS .,.... ~ lllf' .. .Jlr- . ~ · • Wipe-clean static electricity ·. • Each mat includes acoiled • Decrease friction • Accommodate the whole keyboard Size: 11.5" x 22" C21030.........................$19.95 ~ ? Z.,.. , • • ;. ~ ·• ? 4 --------SYSTEM ANTI-STA TIC MATS • Wipe-clean static electricity · * Each mat includes acoiled • Decrease friction • Accommodate the whole PC, Printer & keyboard Size: 23.5" x 23.5" c 2103 1..........................$ 29.95 ) • ~ .' • . ~ ,:=:::::-----..:=..:~:1] One computer can drive 10 VGA monitors using the Buffer • Utility for Analog Signal Input • Minimum video response of 120MHz at -3dB • Compact size Approx: 330mm x 235mm x 70mm • Will drive monitors up to 75 metres away from the unit SPECIFICATIONS: • Display Capability: 1024 x 768. 1280 x rn24 resolution • Video Input : Analog (0.7 Vp-p) • Frequency band . width : 120 MHz at -3dB • Power Line input : 100-135 Vac or ~~ * Signal Connectors 9-15 pin D-sub connector for analog slgnals x1 911o................................$795.00 COMPUTER DUST COVER Keep your computer and accessories free of dust and grime while not in ~~~I covers in clear plastic ANTI STATIC TOUCH PAD • • Wipe-clean static C21033.........................$14.95 • ~PONITOR FILJER 12" MONO • ~~~:7::;~:r:~e:d~::e:~~:ges. * Easy installation X99995........................$9.95 • :r-. ,,!IT • ) "1IJ.i, .• • . ~- .,,.., • ~ 4 IC STRAIGHTENER There is a narrower side for 8/14/16/ 18/20 pin IC's and a wider side for 24/28/40/42/48 pin IC's What a great idea for only !!! T12179 $10 95 ....................... · ~ \ \ ..,. .. 1 PROJECT BREADBOARD • 58 .... Group of 5 connected terminals * 4...bus of 25 connected Terminals • Size 80 x 60 x 8mm P11002...........................$5.95 NEW FUSES Thermal Fuses 72C 64mm S16200 ...................$2.65 128C 64mm S16210 ..................$2.65 141C 64mm S16220 ...................$2.65 167C 64mm s16230...................$2.65 228C 64mm 2 65 $ · :~:~~4~~............ S16250..................$2.65 • Mini Tower cover set .----;... 152C 64mm ~ ~ C21067 .......................$12.95 /." ____ __J. S16260....... . ..........$2.65 '_ ··- 4 • ( • \ ~ ' , I: ~ ~ ••, lllf' • ~ ' , .. ~~~~:;~~~.~.~~~~.~~~ 14 . 95 /~~=====~=====~ • AT cover set ' •'"::"'r'!\~>)llli\ LED BARGRAPHS ~ ~ c 21068.......................$ 16.95 '----' An end stackable L.E.D bar a S.I.L pin .., ....., ' , ~ X99990........~~'.'..~!~.':'.~.....$18.95 15" Co X99991.. .................!~~!. .....$59.95 • XT cover set C21066 .......................$14.95 package. Suited for solid state meter movements and level indicators (10 leds In a row) • ). X99992... ....~X:'..~!~.':'.~.$79.95 X99993......~.1:i:'..~!~.':'.~;.$89 •95 • 14" Monitor dust cover C21061 ........................$9.95 1-9 210180 ...........................$3.95 .......J .. .• ~ lllf' .) · ~ M16820..........................$82.50 • Lock & Keys C16020 .............$15.95 ~ ; 10+ $3.50 • • • ·. ~ '--.-~--~--__.,( ---h-- --1 - ~--t~ - --..- ~ - --~-1--,-.~.....;.--~- ~- --....-~- -,-.__---4 - -~---..-.. -1--,.-.- ----...Jr .. . rie I 2KW SINEWAVE INVERTER The Flagship of our Solar products range. This high power true Sinewave Inverter produces 2000Watts contlnious at 240 VAC from a 24VDC Battery source. SPECIFICATIONS Input Voltage 22-28VDC Output Voltage 240VAC EMI Suppressed Output Power 2KW continious Output Power Peak 3KW for 300mS Standby current 3AMPS DC Full Load current 114AMPS DC Output Regulation <8% Efficiency > 80%at 2KW Harmonic Content < 10% distortion 50 Hz accuracy Crystal locked The 2Kw Inverter will power fridges, washing machines, microwaves, ovens, Power tools, Lights and vldeo/Hifi equipments. In conjunction with a suitable solar panel array and battery bank, t he Inverter could form the basis for a remote supply system for farms or applications where no mains supply is available. Kits will be available later this month. Assembled & tested units as well. We will be supplying all ancilllary products for this project. KIT $1950* +Tax if applicable A & T $2750* +Tax if applicable *Prices are subject to change due to the specialist nature of objects in this unit. Multi strand heavy duty cable, high capacity batteries, solar cells, battery connectors etc. are available as well. ~ RS232 2 Way x,9120•....•.•$39.00 RS232 4 Way X19125 .......•$59.00 Centronics 2 Way Xt9130 .........$49.00 Centronics 4 Way X19135......... $69.00 RS232 2 X 2 X19140... ......$79.00 Centronics 2 x 2 x,9145.........$79.00 2 Way DB9 + Keyboard X19170......$49.95 4 Way DB9 + Keyboard X19175 ......$59.95 2 Way VGA + Keyboard X191ss......$59.95 4 Way VGA + Keyboard X191B6......$69.95 PLUS MANY MORE ! ! . s'-;'o~~~ LA;~, - ~ SOFTWARE S P E ~ ETl-569: SOLAR GENERATOR KIT The ETl-569 Solar Charger is designed where mains power is unavailable. It Is ideal for remote data acquisition stations, caravans and boats Of course the are other solar chargers around, but these are extremely expensive. With the ETl-569 the emphasis is on simplicity and cheapness. K10005 ......................................$13.95 Sim City .........................................$74.95 Sim Ant. .........................................$84.95 Sim Earth .......................................$94.95 Aces of the Pacific ........................$84.95 B17 Flying Fortress ......................$94.95 Push Over ..................................... $74.95 Links 386.......................................$84.95 Troon-Course disk ... ;...................$34.95 Pinehurst-Course disk .................$34.95 Indiana Jones - Fate of Atlantis ..$74.95 SQUEEKV CLEAN Allows television sets with UHF only to recieveUHF Recieves both "on air" and "off air" UHF signals • Lets you recieve UHF channels 28and many computers VCR's without having to buy a complete new television set. • Converts T.V. games Computers with UHF signal outputs to VHF *Power Supply :240 volts AC 50Hz L15021 ...........................................$99.95 . // -f.· ·-./.,,,,, :••';·:•·.·-:• ·-;. ,;;.;~~-. ;~ :..{ Surge Stopper Protects against surges spikes - transient - Lighting - RF • Office equipment *Sound Hi/FI equipment • Personal Computers*Amsteur & CB radio • Video equipment *Television Receivers Made in Australia X10040 ...............................................$245.00 EXTREMELY POPULAR Allumlnlum T o r c t ~ Black White & Grey Emulation scanner with powerful Photo/image Editor & Multilingual Omnifont OCR. Three grey emulation modes allows you to bring excellent reproductions of pictures into your reports, brochures,etc. Perfect for scanning line art. Scan objects in resolutions from 100 to 400 dpi. Inc. GO-CR-Scans text to text file. Windows based operation makes it so easy. This month retailing for only VERBATIM DATALIFE ALL DISKS INCLUDE WRITE PROTECTS & ENVELOPES BOXES OF TEN DISKS LIFETIME WARRANTY 1-9+ 5 1/4" 5 1/4" 31 /2" 3 1/2" 10+ 50+ 100+ 500+ OS/DO $4.35 $4.20 $4.10 $4.S)O $3.90 OS/HD $8.10 $7.90 $1;75 $7.50 $6.60 OS/00$7.50 $7.40 $7.30 $7.10 $6.60 OS/HO $12.95 $11 .95 $11.00 $10.50 $9.90 1-9 boxee 10+ 3 1/2"00 $19.95 3 1/2"HD $45.95 5 1/4"DD $14.95 5 1/4" HD $23.95 $18:95 $42.95 $12.95 $22.95 1-9 boxee 3 3 5 5 1/2"DD $21.95 1/2"HD $42.95 l/4"00 $17.95 1/4"HD $22.95 10+ 1-9 boxea 10+ $20.95 $41.00 $16.95 $21.95 31/2"DD $19 .95 $18.95 3 1/2"HD $34.95 $32.95 5 1/4" 00 $10.95 $9.95 5 1/4"HD $15.95 $14.95 YOU'LL HAVE TO GO A LONG WAY TO FIND DISK PRICES LIKE THESE, SAVE ON OUR GREAT RANGE OF EPSON PRINTERS 5 L.X•400 80 Col. 9 Pin Dot Matrix. 190 Cps Draft 30 Cps NLO. Pull Tr actor C22054 ...................$249 LQ•1070136 Col. 24 Pin Do t LX· 850 90 Col. 9 Pin Dot Matri x. 240 Cps Draft 48 Cps NLO. Pu~h Tractor. Smart Park Feature C22074 ....................$365 ,... ,... ~ ~ ~ • Matrix. 180 Cps Drat~ 60 NLO Pull Tractor C22070 ............... ...... $439 C22066 ............................ L0•570 80 Col. 24 Pin Do t Matrix. 252 Cps Drat~ 84 Cps. NLO Scalable Fonte 8 to 32 pointe, 11 LO Fonta 360 x 360 DPI. Top. Re ar. SQ-850 80 Col. 24 Nozzel ink je~ 600 Cps Draft, 198 Bottom and Front paper $1 399 l l : 241-243 WRIGHT ST, ADELAIDE. J ~:;:~o~onvertable Push/Pull I I 1 Ph : ' (08) 211 7200. Fax : (08) 211 7273 1 L-----------------------------JI ~1Li~~;~:~··cAR·o·oK··RA i~·::::: :~: • ~ ,.!fir • • • .. • ~ ~ • . ·• .l/i4 2 WAY FOO CONT. ...........••.•...•..••.. $89 4 WAY FDD CONT..............•...........• $129 VGA 16 BIT 256K .............•.•........... $59 VGA 16 BIT 512K ............................ $79 VGA 16 BIT 1 MEG ...................•..•. $129 16M HO CACHE CARD OK RAM... $495 HDD IDE /FD0 ................................. $19 HDD IDE/FDD/SPG ...•...•...•.•.......•.. $39 8 BIT ETHERNET CAR 0 .. ..•.•..••..•...$195 16 BIT ETHERNETCARD•.........•....$245 AT HD CONTROLLER .•.................. $149 MULTI 1/0 CARD ......•............••••..•••• $99 MONO COLOUR CARD.•..••..•......... $69 EGA CARD ............................••..••.... $99 DIAGNOSTIC CAR0.•..•..••.....•..••.•.~$795 TTL PRINTER C A R D ~ •. $79 FAX CARD............... ••.••.$595 6M AT EX/EXP•.•..•..•..:~.~:..... .......... $225 PARADISE ACCELERATOR ........... $325 PARKEET ACCELERATOR ..........•..$375 LQ•2550136 Col. 24Pin·Dot Matrix· 400 Cps Drsf~ 133 LO Colour Sta ndard.Push Tractor. Smart Par!< Feature. C22064 .......................... $1995 $ 995 :ll, ' i- · HARD DRIVE SPECIALS MEMORY MEMORV- 40M SEAGATE DRIVE................................... $299 85M HO 6ms T.T ACCESS. VOICE COIL 2 YEAR WARRANTY...................................... $399 105M HD 6ms T.T ACCESS ...•.....................•. $449 120M KALOCK .ORIVE ................................... $475 126M HO 6ms T.T ·ACCESS.VOICE COIL 2 VEAR WARRANTV...................................... $515 170M 6ms T.T ACCESS................................ $595 212M HD 5ms T.T ACCESS. VOICE COIL. 2 YEAR WARRANTV...................................... $699. NEW 340M H.D 5m s T.T ACCESS ...............$1295 4125s-08 .....s2.95 s2.15 s2.5o 44256-07.....$7.50 $6.50 $5.9D MOTHERBOARDS -==::: 286·1 6/2C .:...................... ...• $110:-oo 386SX-25/31.............. •............'$190.00 386SX-33/41 ...••.••.• .. ... ... ... $265.00 386-25 ............:.......... ........ $365.00 386-33 64K CACHE.... .. •••• $335.00 386-40 64K CACHE...... •.. $365;00 386-33 128K CACHE....... · .... $395.00 486SX-20 .......................... ......•.•...$425.00 486SX-25 .............................. ............. ......$475.00 486SX-33 .................................................. $525.00 486· 33 256K CACHE .............................. , $1195.00 486-50 256K CACHE............................... $1495.00 486-33 EISA.............................. ,.............. $2895.00 1.9 SIMMS 1-9 256K-60 256K-70 256K-80 1M x 9-70 1M X 9-60 4M x 9-70 $29 $23 $21 $79 $89 $292 10.99 10-24 $27 $21 $19 $77 $85 $279 . .'i ■ PRICES ARE WITHOUT PADD LE CARDS & BRACKETS IBM CARDS ~ c22012........................ $1249 LO· I 060 136 Col. 24Pin Dot Matrix' 292 Cpe Drat~ 98 Cps LO. Colour Standard.Push Tractor. Smart Par!< Feature. C22096............................... $1,395 LQ•870 80 Col. 24 Pin Dot Matrix.330 Cps Drat~ 110 · Cps NLO. Scalable Font e. C220 7o........................-. .... $449 8 to 32 pointe, 11LO Fonts. ,- - - - - - - - - - - - - - - - - - - - - - - - - - - - - , 360 x 360 DPI T R ADELAIDE STORE NOW OPEN! Bottom. & Fr~ni°:;pe:a;~ed -~ ~ ? C22127 ........................... ~ LO· I 00 90 Col. 24 Pin Do t Matri x 200 Cps Draft. 72 LO. Built-in sheet feeder.a font•. 2 ecalable fonte. $795 LQ• 1170 136 Col. 24 Pin Dot Matrix. 350 Cps Draft .• 110 Cps NLO. Scalable Fonts. 8 to 32 poin~ 11 LO Fo nts. 360 x 360 DPI. Top. Rear. Bottom. and Front Paper Feedpaths. Convertable Push/Pull Tractor feed paths, Converta~ e Push/Pull Tractor. C22068....................... $649 Cps LO, Push Tract or, Smart Park Featu re. PRINTER CAR0 ............•..•. .•.. .•....... $19 GM RAM CAR0..... .........•.................$249 2 PORT SERIAL CARO.................. $39 GAMES CARO ...........•.................... $1 9 .. Matrix. 252 Cps Draft .• 84 Cpe NLO. Scalable Fonts. 8 to 32 poin~ 11 LO Fonts. 360 x 360 DPI. Top. Rear. Bottom, and Front Paper Feedp1th1 1 Convertabl~ Push/Pull Tractor LQ•400 80 Col. 24 Pin Dot FX· 1050 136 Col. 9 Pin Do t Matrix, 264 Cpa Draft, 54 Cps NLO. Push Tractor. Smart Park Feature. C22067 ......................... $1 025 C2205 2...................... LQ •860 80 Col. 24Pin Dot Matrix' 295 Cps Draf~98 CPS LO. Colour Standard.Push Tra ctor Sm art Park Feature. C22073 ................. $1 095 SQ-2550 80 Col. 24 Nozz.el Ink jct. 600 Cps Draft. 198 Cpe LO • Push Tractor. Smart Park Feature. C22099 .........................$1 99 5 100 + t ,,, I 25+ $26 $19 $17 $17 $15 $75 $73 $81 $75 $269 $259·11,I I f , ~ ~i,..t· SIPPS 1M x 9-80 256K-60 $85 $84 $26 $25 ~; SUPAVGA COLOUR 'MONITOR "3 YEAR WARRANTY" This stylish and reliable monitor has been designed for Australian conditions & comes with a 3 year warranty. PECS: cte: 14.. 90• deflection. darl< tin~ non -glare. Display aize: 245+/Smm x 180+/-Smm x 180+/-5mm Reeolution: (max): 1024 x 768. Dot Pitch : 0.28" only $439.00 tJ..fJ:i SUPER VGA MULTISCAN COLOUR MONITOR 0.28" D.P L.:::============~===============================J 1».-L.~~ •r 1».•·t~~ •.r 1.•.-L~,,._•··I •1.•.-L~~ •.r 1.•.-L.~ ..t• ·~ • .l-. - • .1-. - • l♦ - • ,-- \ ..4 J. I ,!' • ·• \I -.t'-• CHRISTMAS COMES BUT ONCE A YEAR! I with FREE MINI SPEAKERS The sound blaster II ls the ultimate s ound board 4 ( ). l ( ). ..,. ( ). ' TEXT-TO SPEECH SYNTHESIZER • 11 VOICE FM MUSIC SYNTHE$IZER • DIGITIZED VOICE OUTPUT WITH 4KHz TO 44,1KHz SAMPLING RATE , DIGITIZED VOICE INPUT (8 BIT ANALOGUE TO DIGITAL CONVERSION) , BUILT-IN MIDI INTERFACE FOR CONNECTING INSTRUMENT. , MUSICAL BUILT-IN JOYSTICK PORT • BUILT-IN STEREO POWER AMPLIFIER -T ·, ' •f - - .•. : (•, ...I·.·.' ! ~-.•.• A super VGA dlap·l ay adaptor designed for users of Windows and CAD applications. It accelerates Window• by wind owing programa by up to 15 timea that of a atandard VGA. It oupporta reaolutlon of up to 1280 x 1024 and a pallatte of up to 32K colours. Comes packaged with aoftware utilitiea and drlvera • 1 Mbyte of on-board Memory Emulates IBM PS/2, VGA, MCGA, CGA, MDA and Herculeadlsplay adaptor• MORE THAN JUST - LISTENING EXPERIENCE! THE SOUND BtASTER PRO CARD EASILY INSTALLS INTO YOUR IBM PC/AT ANO 100% COMPATIBLES. (286 AND HIGHER RECOMMENDED) PACKAGE INCLUDES : • SOUND BLASTER PRO CARD • RCA AUDIO CABLE , 5.23" AND 3.5" DISKETTES • VOICE EDITOR II • SBTALKER (TEXT-TO-SPEECH SOFTWARE) • FM INTELLIGENT ORGAN SOFTWARE • CD MUSIC PLAYER • MMPLAY PRESENTER • DOS DRIVERS AND WINDOWS DLL • SB MIDI· A MIDI FILE DRIVER SOUND BLASTER PRO V2 MORE THAN JUST- LISTENING EXPERIENCE! THE SOUND BLASTER PRO CARD EASILY INSTALLS INTO YOUR IBM PC/AT AND 100% COMPATIBLES. (286 AND HIGHER RECOMMENDED) PACKAGE INCLUDES: • SOUND BLASTER PRO CARD ( ~~ pRg : ~;.~t~1r.:l~:ETTES , SP PRO MIDI SEQUENCER SOFTWARE • VOICE EDITOR II • SBTALKER (TEXT-TO-SPEECH SOFTWARE) • FM INTELLIGENT ORGAN SOFTWARE • CD MUSIC PLAYER ~~:ii~~~~~G PARROT MIMICS YOUR SPEECH FM INTELLIGENT ORGAN • CREATES ORCHESTRA LIKE MUSIC USING YOUR PC KEYBOARD AS INPUT. JUKEBOX. A WINDOWS THREE APPLICATIONS. RUN WINDOWS UP TO 3 TI MES FASTER WITH THE PARADISE ACCELERATOR CARD X18012 .......$165.00 • SOUND BLASTER PRO \ I •f » so HURRY IN FOR THESE BARGAINS! •BUILT-IN STEREO POWER AMPLIFIER BUNDLED SOFTWARE INCLUDES• SBTALKER FOR READING ASCII FILES & Di, SBAITSO VOXKIT-VOICE DEVELOPMENTTOOLKIT that easily plugs into any slot In your IBM, PC, XT, AT, 386, ell:. • -.t,•••••-.f .• I Only $325.00 • SBSIM - A SB STANDARD PROGRAMMING TOOL SYSTEM REQUIREMENT • IBM PC/AT OR 100% 286 ANO HIGHER COMPATIBLES (286 AND HIGHER RECOMMENDED) • MINIMUM 512KB RAM • DOS 3.0 OR HIGHER • EGA OR VGA (VGA RECOMMENDED) X18021.$319.00 • MM PLAY PRESENTER • DOS DRIVERS AND WINDOWS DLL • SB MIDI· A MIDI FILE DRIVER • SBSIM • A SB STANDARD PROGRAMM ING TOOL \ ~1:fJg~~:;~j1 / SYSTEM REQUIREMENT • IBM PC'AT OR 100% 286 AND HIGHER COMPATIBLES (286 AND HIGHER RECOMMENDED) • MINI MUM 512KB RAM • DOS 3.0 OR HIGHER • EGA OR VGA (VGA RECOMMENDED) X17050 ........$345.00 ~~:t.fl~ ' .1!.,. NEW CD ROM PACKAGES FOR BUSINESS, EDUCATION AND FUN! Tho O~•OM Ori~ ,ro••H O ' " " ' ' ""'000... 0 . . . o,d """ 0~ . . -""'=• mullimedia Information technology. A key component in the Multimedia Upgrade Kit, it -- .,. , has s maaa storage necessary to run the data-intensive multimedia appli cation. CD-ROM ·drive will also flt into any 5.25" half-height drive bay on your IBM compatible (Xra not ( • ). • . 4 ( ). ,., I. ( ) I?'.'.'.'.'.'.~ compatible) ~ ~~ FEATURES: ~ , Includes Sound Blaster Pro (short version) . , CD quality sound (you can even play normal audio CD's) ~ --- ~ · • Ability to display photographic images & motion video (requires VGA display) '--"'===-----_Ii , Audio Jacko for quality sound through your own apeaker ayatem- 630 Mb of data on one compact disc , Full compliance with multimedia extenaiona 1,0 , Front mounted stereo headphone jack and volume control We now provide three different upgrade pacakgea. JO - a ·,, ' . . )i\ v'.·,( ,.-·' . ', ·-~ . .' MULTIMEDIA UPGRADE KITS BUSINESS PACK Includes: Sound '3laster Pro 2 Sound Card• Internal C.D-ROM Drive• Microphone• 8 C.D titles comprising of MICROSOFT WINDOWS 3.1 (with Multimedia extensions) - Fuh Implementation of Microsoft Windows 3.1, 10 Mb of help data, multlmedla accessories Including Music Box, Sound Recorder, Juke Box and more , MICROSOFT BOOKSHELF- A complete reference library with an Encyclopedla, Thesaurus, Atlas, Quotations, Book of Facts, Dictionary and Columbia Dictionary of Quotations • CREATIVE'S SOUNDS- Superb music and sound effects. lncludn audio clips, 2!1 compositions In 4 formats and up to 111 sound effects• Macromind Action• Authorware Star• Microsoft Works• The Selectware System and Sherlock Holmes. $1299.00 EDUCATIONAL PACK Includes: Sound Blaster Pro 2 Sound Card• Internal C.D-ROM Drive • 7 C.D Titles comprising of: • MICROSOFT BOOKSHELF- A complete reference library with an Encyclopedia, Thesaurus, Atlas, Quotations, Book of Facts, Dictionary and Columbia Dictionary of Quotations • CREATIVE'S SOUNDS- Superb music and sound effects. Includes audio clips, 29 compositions In 4 formats and up to 111 sound affects• Mammals the Multimedia Encylopadia • The Select ware System, Sherlock Holmes • Jonas In the fast lane and Multimedia Sampler. (Windows 3.1 available with this kit for $70 extra ..$1099.00 r.:.'lr::.-':r."'lr:n'TI':'li:r."F.r.:r.:R"7'1:":r7'.:~ C.D-ROM Drllve and cables , Complete with 7 C.D Titles • MICROSOFT BOOKSHELF-A complete reference library with an Encyclopedla, Thesaurus, Atlas, Quotations, Book of Facts, Dictionary and Columbia Dictionary of Quotations • CREATIVE'$ SOUNDS- Superb music and sound effects. 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Approx. 1.8~ per copy $1095 ExTax ONLV $1379.99 X19961 ...............................................................$189.00 RITRON COMPUTER SYSTEMS / 286-16Mhz (LM21) ............. $1289 386SX-25Mhz (LM31) ......... $1359 ~ 386SX-33 (LM41)................ $1439 ,: 386-33 (LM57) 64KCacha .. $1519 ~ 386-33128K Cache............ $1539 ""-------.; 386-40 (LM65) 64K Cache.$1539 ~ 486SX-20 (LM85)................$1589 ~ 486DX-33 (LM157) ,. 256K Cache ........................ $2279 ~ 486DX-50 (lm172)256K ...... $2679 ~ 486-33 EISA ........................ $4039 :i ~ . . . .. . . . . All Salas Tax exempt orders to: RITRONICS WHOLESALE 56 Renver Rd, Clayton, Victoria. Ph: (03) 543 2166 Fax: (03) 543 2648 Mail order & Correspondence P.O BOX 620. Clayton. Victoria, 3168. Do you hava an application for FREE anargy? Doaa your alactrtclty bill glva you nlghtmaras? Can you afford Iha lnauranca premium■ when all your night !Ima visitor■ s~a you attar tripping on dark paths? 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Each kit contain• a eel of precut plywood, PVA cement, assembly Instruction sheet, solar cell module, musical IC or amall DC motor, wire and sand paper. 219044 Aeroplane ........... $19.95 Z19046 Gramophone...... $19.95 SOLAR CAR BATTERY CHARGER Never worry about your car battery going flat when left without being uaed over a prolonged period of time. Simply place the aolar power unit on your dash or near I window In your garage and plug It Into your car cigarette lighter. The unit consists of 1ol ar cells in a 219048 Hellcopter........... $19.95 DYNAMO & SOLAR A /FM RADIO WITH 4 WAYS POWER BACKUP '~ l~ SOLAR MOTOR KIT 219040 ........................ $9.95 SOLAR BICYCLE WARNING LIGHT AND BATTERY CHARGER. for 2 'AA' size batteries Z19056 ..............................$19.95 Leam what aolar power la and how to build your own solar ayatam. With thia great kit you can make an electrical circuit. l.Hm how to Increase voltage, learn how to Increase current, learn how to make • solar panel, 1188 solar power to produce the energy for 1 radio, calculator battery charger or 1.SV caasette player . 219042 .................... $22.95 SOLAR MUSICAL KEYCHAIN WITH LIGHT. Never lose your keya again with thla clever lltUe device. The aolar powered keychaln with light will let you find where you left your key ■ where you left them juat by listening to music. The ■ olar powered light will slwaya let you find that Illusive keyhole in the dark. A very handy idea and all run on FREE powerl 219060 ................................ $4.95 ROD IRVING ELECTRONICS Pty. Ltd. Eat. 1977. ACN.005 428 437 • HEAD OFFICE: 56 RENVER RD, CLAYTON. PH: (03) 543 7877. FAX (03) 543 2648. • CITY: 48 A'BECKETT ST. MELBOURNE. PH. (03) 6636151 / (03) 6391640. FAX: (03) 6391641. • OAKLEIGH: 240C HUNTINGDALE RD. OAKLEIGfj. PH: (03) 562 8939. 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Ph: (03) 543 2166 Fax: (03) 543 2648 Mall order & Correspondence P.O BOX 620, Clayton, Victoria, 3168. , SERVICEMAN'S LOG A dogged approach is justified It's funny how the job you think is going to be a snack can turn out to be a right proper bomb, while something you are tempted to write off at the beginning can sometimes come good. But it does happen and my main story this month is an example of the latter. The story started when a new customer drove up to the shop with a very large TV set in a box trailer behind his car. It turned out that he had just moved into the area and one of my regular customers had directed him to me. I recognised the set at a glance - a Kriesler 5·9-1. Well, that was my first negative thought. This was the first Kriesler on the market when colour TV was introduced in Australia, back in 1975, making it anything from 15 to 17 years old. Granted, they were a good set in their day but spare parts can now be a problem. Then came the customer's comment: "It just stopped. And there was a smell of burning and some smoke out the back". Our loss is your gain Fracarro's ESVU2. The really low loss VHF/ UHF mixer with areasonable price tag. Peter C. Lacey Services Pty. Ltd. P.O. Box 676 (74Fulton Ad.) Mount Eliza 3930 Tel:03 767 2077 Fax:(03j 767 3460 ACN006893438 84 SILICON CHIP Well that didn't sound too good either. In any case, I didn't feel like manhandling the thing into the shop - even with the owner's help - only to find that it was a write-off and then have to manhandle it out again. Fortunately, the set was quite accessible on the trailer and it took only a few moments work with a screwdriver to get the back off. And while I was doing this, the owner nominated the lefthand side as the area from which the smoke had emerged. This suggested that the fault was somewhere on the deflection board which carries the vertical and horizontal circuits. And so it proved to be. With the back off, I could dearly see the source of the smoke and smell. It was roughly in the centre of the deflection board and involved two capacitors: C760 (0.33µF) and C761 (0.39µF). These are connected in parallel and are then wired in series with the horizontal linearity coil (T761) and the horizontal scan coils. This is not the first time I've encountered trouble in this area. It's not unusual for one of these capacitors to fail, either directly or due to a dry joint. The result is severe horizontal overscan; normally enough to bring a response from the customer - but not always. Some people will watch anything! . And if both capacitors fail? Ah well; then you can be in real trouble. Among other things, the EHT can rise to around 50kV, while excessive voltage on the scan coils can punch a hole through the neck of the picture tube. For now, it was obvious that one of the capacitors, C760, had a dry joint on one of its leads. But it was around C761 that the real damage had occurred. As with C760, it had a dry joint (as I confirmed later) but so much heat had been generated around it that the board had been charred and the track damaged. More importantly, both capacitors had been out of action, at least briefly, before the set was turned off. Had the picture tube survived? Again, I couldn't be sure from a casual inspection , although there were no obvious cracks and there was no discoloration inside the glass, or obvious damage to the screen, as often happens when air enters. I explained this risk to the customer, adding that I thought the picture tube was intact and that it was probably worth taking a punt on the other fault. I suggested I take a closer look and advise him if I thought the cost was going to exceed $100. He said up to $150, I said OK, and we carried the monster into the shop. Tube OK When I finally gained proper access to the works, I quickly confirmed that the picture tube was intact before tackling the two capacitors. C760 was easy - I simply resoldered its connections. C761 was another matter; not only had the board been damaged but the capacitor itself was also damaged, one of its leads having come adrift. Fortunately, I had a replacement capacitor on hand, in spite of the unusual value. I cleaned up the damaged board, fitted a wire link in place of the damaged track, and then refitted the capacitor. I then carefully examined the rest of the board, checking for dry joints or other obvious trouble spots , but found nothing suspicious. Dead as a dodo It was time to switch on. Ever the optimist, I thought the set might come I I I r-----' .. ,v, I ----- --, I : I .• ,_ I L-..4-______:.4[I}-4--_J ii ~, I I "I ~---+---.1------r-..---"' I ~I i ~I u, i;.i--m~;-i ~I ~I L....;n:llill!l-,1.-.. I 1. ' ,_ - - - "'I i: ----- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - G. I I Fig.1: the switchmode power supply circuit in the Kriesler 59-1. The four rails generated by the supply are on the right, starting at the top right corner. The sub-board, or "power supply control unit", is at lower left. good. Alas for my hopes; it was as dead as the proverbial dodo. Back to square one. A little preliminary testing pointed squarely at the switchmode power supply; it simply wasn't working. And this was where my stockpile ofboards came to the rescue. By substituting a known good board one can quickly determine whether the original board is faulty or is being prevented from working due to a fault somewhere else. In this case, there was no doubt. I fitted a replacement board and the set came good. When I took a closer look at the power supply, it was immediately evident that someone had been there before me. And they'd been pretty heavy handed. In fact, they were probably looking for the fault I subsequently located. Minor components had been changed and various joints resoldered, and it all looked a bit messy. Worst of all, a 2.20 10W resistor (Rl 11) had been replaced with a couple of 3W units in parallel. This may have been adequate electrically but I had a spare on hand and this was fitted as a matter of course. I then went over the board, tidied things up a bit, remade a couple of joints which I thought looked suspicious, and put the board back into place. I didn't really expect it to work and it didn't. So I tried another tack. The power supply consists of two boards: (1) a main board; and (2) a sub-board called the "Power Supply Control Unit" which connects to the main board via an edge connector. So which one had the fault? I have a swag of sub-boards, so I simply fitted one in place of the original unit. And this time it did work, which meqnt that the fault was on the subboard. But before I could pursue that line, I realised that something else was wrong. The picture was displaying an effect sometimes known as "cogging" or "gear wheel effect". More exactly, it takes the form of horizontal displacement of vertical lines, usually in a square wave pattern. The term "gear wheel effect" comes from the effect it has on test pattern circles - it turns them into a crude imitation of a gear wheel. In this case, there were many such displacements although the amount of each displacement was quite small. In fact, at a normal viewing distance, on ordinary program material, the average viewer may well have not noticed it. But on a test pattern, it was clearly evident. More importantly, it decreased with time and after about 15 minutes, it had virtually disappeared. I didn't have many clues at that stage. All I knew for certain was that it appeared to be thermally sensitive and that it was in the power supply somewhere, because a replacement board cured it. Also, I tipped that it was probably a ripple problem in one of the supply rails, most likely due to a faulty capacitor. · Hula girl In broad terms, I likened it to a problem known as the "hula girl" effect. This was common in early TV sets and was caused by mains ripple in the horizontal system. However, most modern sets use switchmode supplies and so any ripple would be at much higher frequency, thus giving a far greater number of displacements. Partly due to pressure of other work, DECEMBER 1992 85 SERVICEMAN'S LOG - CTD and also to give me time to think, I put the set aside until the next day. I didn't have any inspiration in that time but, when I switched it on again, from dead cold, the effect was more pronounced than ever. So was it a thermal fault or a faulty electrolytic that was being partly reformed by applied voltage? I tended to favour this latter thought now, so I started looking at all likely capacitors in the power supply. The reader can best follow this by starting at the top right corner of the accompanying circuit diagram (Fig.1). First, a 205V rail is derived from pin 7 of the switchmode transformer (T131) via diode D131, capacitors C131 and C132, and inductor 1132. These two capacitors were measured for capacitance and checked OK. The next rail down the circuit is the main HT rail at 155V and the two capacitors involved, C137 and C138, are both in a single can. Initially, I thought I'd struck oil here because one unit measured zero capacitance. I was able to fit a replacement pair but it had no effect, at least not on this fault. Further down the circuit again is a 28V rail, involving C142 and C143, but I could find nothing wrong here either. That left only a very low volt- age rail, designated as "Horizon. Osc. Quick Start". Apart from resistor R14 7, it involves only one small capacitor (C147) and diode D147. I didn't really expect to find anything wrong with the capacitor and a quick check confirmed this. I finally turned to the CRO and checked the ripple on each supply rail. This didn't reveal very much. Most of the rails showed some ripple but how much was acceptable? I tried comparing it with a known good board and while the faulty board seemed to be marginally higher, even after the fault had cleared itself, it was all very inconclusive. Where to now? So where to now? Apart from proving that a lot of things were not the cause, I hadn't made much progress. But I did have second thoughts about one thing. Whereas I had been visualising a sick electrolytic capacitor that was reforming itself, my failure to find such an electrolytic had swung me back to my original theory - a thermal fault. Perhaps this influenced what happened next. ...,. ~ ~~ -1-\E- HA.'D -:S-UST MOVE.t> IN'T"O -me:. A'REA ANO -ONE. OF M.'( ~E,G,ULA'R. cus,o~~~s HAO t:>l'R.E-C.Te:,p HlM -ro I\AE-oe, 86 SrucoN CHIP In any case, while I was going over all I'd done and seeking further inspiration, I noticed something different about the board. All the diodes in these rail circuits were similar Mullard types (mostly BY206). And they all looked the same: plastic encapsulated, green in colour, and about 5mm in diameter and 7mm long. At least they should have been and they all were on my own boards. But on this board, D147 in the "Quick Start" rail was a ring-in. There was no discernible type number on it and it was a small glass-encapsulated type (commonly called a low signal diode). How or why it had been fitted remains a mystery. Contrary to other service work on the board, it didn't look like a bodgie; it was as neatly fitted as any other component. Yet I couldn't imagine it being fitted at the factory. Acting on a sudden impulse, I reached for the freezer can and gave it a squirt. The set had well and truly warmed up and the fault had vanished by now but the effect of the freezer was dramatic; the fault was back in full force instantaneously. And that was it. I pulled the bodgie diode out, fitted the correct type, and that was the last of the problem. In fact, the set now delivered a firstclass picture. So, after all my hours of hard work and frustration, I had stumbled across the fault virtually by accident. It was all a bit of a blow to the ego but no less welcome for all that. I checked the diode after I pulled it out and the fault was quite clear cut; it had significant reverse current leakage at ambient temperature but this fell to virtually zero with moderate heating. That much established I decided to trace the rail and determine its function. In fact, it ran to the deflection board and to another subboard (or "module"), CU701, called the Line Control Unit which contains, among other things, the horizontal oscillator. At t);iat point, I reckoned I'd traced it far enough. But why the bodgie diode was fitted in the first place and why it had failed is anybody's guess. Perhaps the 25Vp-p applied to it was just too much. And what were its specifications anyway? We'll never know, of course. But at least the problem was solved and I ii EHT GENERA TOR Based on a brand new, very compact modern EHT flyback transformer which includes an EHT diode rectifier. We supply the transformer, a very simple circuit, and the components to suit. All you need to make a very simple EHT, DC or • pulsed AC supply. Powered from 12V DC supply. Great for EHT experiments, EHT testing, plasma displays, etc. Total price for the transformer and the components is ONLY: LASER POINTER VISIBLE LASER DIODE BARGAIN Small PCB Assembly based on a ULN2232 IC. This device has a built in light detector, filters, timer, narrow angle lens, and even a siren driver circuit that can drive an external speaker. Will detect humans crossing a narrow corridor at distances up to 3 metres. Much higher ranges are possible if the detector is illuminated by a remote visible or IA light source. Can be used at very low light levels, and even in total darkness. With IA LED. Full information provided. The IC fs_ly, is worth $16! OUR PRICE FOR THE ASSEMB&LY Brand new 5mW-670nM laser diode, plus a collimating lens, plus a driver kit plus hardware, plus instructions. sag High quality pen sized 5mW laser diode pointer for teachers, doctors, etc. On Special Item No. 0164 s1so Item No. 0101 . LJJJ m Brand new Hitachi LM215XB, 480 X 128 dot displays at a small fraction of their real value. s39 <at> Item No. 0132 Controller IC (surface mount) $5. 28 pages of data $3 , $6 ea. or 5 for $25 Item No. 0163 BARGAIN MONOCULAR VIEWER I Brand new large 640 X 200 dot matri x LCD displays with built in drivers. Limited supply at s30 .. s599 $279 s17 ea or 3 for $45 ea. 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ON SPECIAL <at> $49.90 For two keys, and one decoder kit. For the Argon head only. We also provide a circuit for a power supply. Item No. 0109 DIVERGING LENS Stock up on this LIMITED STOCK surplus item . Circuit supplied. Brand new, 6-12V (6V/50mA, 12V/150mA}. GIVEAWAY at: $6 ea. or 5 for $25 <at> • • A high quality laser beam diverging (beam expander) glass lens, mounted on an aluminium plate, with mounting screws provided. Dimensions: 25 X 25 X 6mm . Use it to expand the laser beam for Holog°raphy, Special Effects, or one of the two lenses required to fine focus a laser beam, for Surveying and Bar Code Reading. sg 90 ,. .. .___ _ _• _ _ __ RING OR WRITE TO OBTAIN A BROCHURE LISTING THESE AND OTHER PRODUCTS AND KITS OATLEY ·ELECTRONICS Brand new Japanese 6V-500 mA Hr. Gel batteries. Fresh stock, charged , and very compact. 57 X 50 X 13mm. Limited quantity at PO BOX 89 , OATLEY , NSW 2223 Telephone: (02) 579 4985 Fax: (02) 570 7910 MAJOR CARDS ACCEPTED WITH PHONE AND FAX ORDERS $7 per pack ~ c__o_r_5_;p_a_cks_f_or_S_3_ 0_ ONLY ......,.. $17 S75 ssoo s10 ea for 10 for $85 Item No. 0130 Telephone display based on an NEC uPD7503 single chip microcomputer and an LCD display. Has ALU, 8 bit serial interface, ROM, RAM , 1/0 lines, time and date display, Xtal. oscillator, and a dedicated LCD display. Features extremely low power consumption at 3.5-6V operation . A connection diagram and microprocessor data is included . CLEARANCE AT: . power pack -that was intended to be used in emergency lighting applications. Contains 17 "D" size 1.2V/4 AHr batteries which can be easily separated into individual cells. New packs in their original packing. Used air cooled Argon laser heads that produce a BLUE beam! Power output is in the 30-100mW range. Limited stock, at a fraction of their real value: Brand new large precision projection lenses, which were originally intended for big screen TV projection systems. Will proiect images at close proximity, onto walls and screens and it has adjustable focussing. Main body has a diameter of 117mm and is 107mm long. The whole assembly can be easily unscrewed to obtain three very large lenses: two plastic and ·one glass. The basis of the cheapest large magnifier or projection system? Experimenters delight at .,:ir·,.... r_ r .,S.~ A complete nicad battery s279 Brand new 6 volt 1 watt amorphous solar panels. Two of these in series make a great 12V battery maintainer/ charger. Incredible pricing. ,- - ._, ._ , 1J , "' NICAD BATTERY PACK Item No. 0121A Item No. 0108 Includes one "Free" rifle or pistol mount. " sggo A very small but compl IA telescope which only needs an EHT power pply, which is provide kit form . New 12V/1 .9 Hr. German Gel batteries. Fresh stock, charged . Dimensions are 178 X 60 X 33mm. Limited quantities at • We should have suggested power supply circuit to suit, at the time of publication. 12V GEL BATTERIES A 5mW gunsight at an unbeatable price. .. New 40mW helium neon (visible red) laser tubes: One metre long! Need approximately 3KV at 20 mA to operate. For discos, displays, holography, etc. Incredible introductory price: a small fraction of their helmet mount binocular real price! ~viewer. Limited stock at sgg If• ~ BIG LASER TUBES Brand new regulated power supplies. 240V mains in - 13.6V or 14.2V at 1.8A continuous output. Less than 2mV Pk-Pk ripple at 1.7A. Has additional output terminals for battery charging. 450 mA maximum . Approved Australian made units that employ a low profile Ferguson PL18 - 40VA transformer, and a regulator circuit (easily modified}, in a very compact , all metal housing: 170 X 95 X 50mm. Mains lead plug attached: 1.8M long. Information/specifications provided . Limited quantities at: High quality ex-military Item No. 0166 •• • • Item No. 0125 An LSI surface mount Includes one "Free" controller IC for this 130mm glass IA filter. display is available elsewhere for about $35. ~ , <', : __, Certified p&p : S6 in Aust. NZ (Airmail) : S10. j SERVICEMAN'S LOG - CTD oo•WOU\•.'t> \-\E: GO OFF H\'S TUC.KE.~ A~t> 'r\AV£ '1"0 'S~ ,-A"'-E-~ TO A ·-poG ?"5Y'CH\A'1'"~\S,-.~ was able to return the set to its owner within the agreed price structure. Pongo's TV set And now, in lighter vein, here is a story about a TV set and a dog. It was related to me by a colleague who has his own shop in a nearby suburb. And because it is secondhand, I cannot answer all the questions which the story prompts. But I will vouch for my colleague's integrity. This is how he tells it. It started with a telephone call from a stranger. Would I come out and have a look at his TV set? Naturally, I .wanted a few more details; I try to avoid house calls if the set is small enough for the customer to bring it in. In any case, I need to know the make and model before making a house call. The upshot was that the set was a Rank Arena model 2601; too big to bring in and, at 17 or so years, probably too old to be worth repairing. The fault was a complete failure, preceded by loud sizzling noises from inside the cabinet. I had a fair idea as to what I'd find and, among the items that I chucked into the van, I included a spare tripler that I had on hand. Original Rank triplers are like hen's teeth these days 88 SILICON CHIP and about as expensive if you can find one. I now use a modified version of another brand but they're still pretty pricey. When I got there, I found that the Rank was obviously a second set, having been relegated to a rumpus room which, by all appearances, was well used. I turned the set on briefly and, yes, there was a series of crackles from inside the cabinet. I didn't really have to guess what the trouble was. The main questions were how bad was it, could the original tripler be salvaged, and had other damage resulted from the tripler failure? I pulled the back off and switched it on again. Talk about fireworks; it put New Year's eve to shame. The tripler was a write-off and I explained the situation to the customer, adding that I could fit a replacement (which I just happened to have on hand). I also told him that I didn't think it was worthwhile. In particular, I pointed out the age of the set, the risk that the tube may be near the end of its life, and that I couldn't guarantee that there was no other damage or that something else might not fail in a couple of months. The money would be better spent on a new set. The owner shook his head. "No, don't want to do that. How much would it cost to fit this triple thing?" I did a couple of quick calculations and suggested a figure of $175, all inclusive. Privately, I felt sure that that would change his mind. But he barely hesitated. "Could you do it now?" It was my turn to hesitate. Did I have everything on hand? "Yeah, all right; I could do it now if you like". Then came the punch line. "Well. I've got to have it fixed. The dog'll go mad ifI don't. You'd better go ahead". Well, I've heard plenty of blokes trying to justify an unjustifiable repair in similar circumstances. It normally goes something like this: "It's not for me y'understand - I don't watch it much. But the missus - and the kids - they get a lot of fun out of it". With minor variations, its a standard routine. But the dog! I've never heard that one before. In fact, I tended to write it off as a bit of leg-pull. Maybe Pongo liked the atmosphere of the rumpus room when others were watching a program but as for taking serious notice of the images, well, you've got to be kidding. In fact, it has always been my impression that animals take little notice of TV or film images. Some people have insisted that their eyesight is such that they cannot see them as the complete images that we do; that they don't have adequate persistence of vision and/ or that they lack colour perception. Others insist that, even if a dog can see the images, the lack of smell tells him that it is not the real thing. And so on. Wild thoughts On the other hand, I must confess that a lot of wild thoughts passed through my brain. Did Pongo show any marked preference for particular programs. "Lassie" perhaps? And how was he expected to express his distress (ie, "go mad") if the set was not fixed? Would he go off his tucker and have to be taken to a dog's psychologist - complete with canine couch - to straighten him out? The thoughts became wilder the more I thought about it. But all I could say was, "The dog? Surely he doesn't watch it seriously". "Oh yes", said the customer. "He really does watch it. Doesn't take his eyes off it and gets quite excited about some scenes. I'll show you when its working". I mentally shrugged my shoulders and went to work. After all, Pongo's money was as good as anybody else's and I'd be rid of the tripler which I had feared I would never use after all this time. It was a straightforward exercise, with no hassles, and in no time at all I was . ready to switch on. The set worked first go and produced a surprisingly good picture, indicating that the tube should last for at least a few more years. I gave it the usual routine onceover for height, width, focus, and colour balance, though I did wonder if Pongo would appreciate these subtle improvements. And as I stood back to admire my handiwork, I couldn't resist a dig at the owner. "Well, do you think the dog'll approve?" He took the hint, opened the back door and whistled. The next minute Pongo bounded in through the door. He was a fairly large dog, seemingly a mixture ofblue cattle dog, kelpie, and a lesser amount of indeterminate breeds. TETIA TV TIP Sanyo 83P chassis Symptom: dark picture. All voltages around the tube appear correct but the beam current is very low. Bears a resemblance to a faulty tube. Cure: R234, an 8.2kQ resistor between the brightness control circuit and the 130V rail, had gone high. This resistor biases the brightness circuit and insufficient voltage throttles the picture. TETIA TV Tip is supplied by the Tasmanian branch of the Electronic Technician's Institute ofAustralia. Contact Jim Lawler, 16 Adina St, Geilston Bay 7015. As he came in the door he was just a big playful dog, ready to frolic with anyone. But the moment he realised that the TV set was running, everything changed. He sat bolt upright in front of it, his gaze never wavering, his eyes following every move on the screen. Electronics Workbench® The electronics lab in a computer! A simple, intuitive and very powerful teaching tool, Electronics Workbench lets students and hobbyists design and test both analog and digital electronic circuits, without the delays and expense of a laboratory . FEATURES • Quick and simple circuit entry • Digital and Analog Modules _included, complete with all components • Simulated instruments: dual trace scope, spectrum analyser, function generator, multimeter, digital word generator and logic analyser • Complete control over all component values and parameters • Print: circuit schematics, parts list, instrument readings, macros • Logic conversion - truth table to Boolean formula to logic gates • Customisable hypertext help system THREE VERSIONS • Professional Version: EGANGA colour display; unlimited components • Personal Plus Version: Monochrome display; unlimited components • Personal Version: Monochrome display; limited to 20 components per ....,. EMONA INSTRUMENTS NSW ......................... (02) 519 3933 VIC ............................ (03) 889 0427 QLD .......................... (07) 397 7427 DISTRIBUTORS Perth .............................. (09) 244 2777 Adelaide ........................ (08) 362 7548 Hoban .... ........ ..... .. ... ..... . (002) 34 2233 In fact, he seemed to be totally mesmerised but the best was yet to come. The program was suddenly interrupted by an ad extolling the virtues of "Doggie Do-Nuts" in which · immaculately groomed canines performed all kinds of acts to demonstrate their preference for this product over all rivals. And now Pongo really did go mad. He was up against the screen , pawing at it, whining, growling, even barking; totally frustrated at not being able to get at the dogs behind the glass. Don't ask me what his motives were but at least I had an explanation for the grubby marks I'd wiped off the bottom of the tube face, and for the scratches on the plastic surround below it. Now I've seen everything. Well, that's my mate's story and we both had a good laugh about it and indulged in a lot of speculation. Why, of all the dogs in the street, was it Pongo? Higher intelligence? Better eyesight? Do all other dogs need glasses?. And how would he react to his master's image (a new trademark?) or to his own image? The possibilities are endless. I'll leave it to your imagination. SC EmonaLAB4 Four instruments in one package! The LAB4 has four full function test instruments: ■ DC POWER SUPPLY Triple output; 5V, 15V, 0-50V with neatly laid out and labelled front panel controls. Also, the LAB4 is compact and only takes up a small space, compared to four bench-top instruments. ■ DIGITAL MULTIMETER Full function, auto-ranging ■ FUNCTION GENERATOR 0.02Hz-2MHz, with SWEEP ■ FREQUENCY COUNTER 1Hz-100MHz input range INDEPENDENT INSTRUMENTS Each instrument in the LAB4 is completely independent and can be switched ON or OFF as required. The LAB4 has only one 240V mains input, saving on multiple power points. · Each instrument is clearly defined EMONA INSTRUMENTS NSW ......................... (02) 519 3933 VIC ............................ (03) 889 0427 QLD .......................... (07) 397 7427 DISTRIBUTORS Perth ...... ...... (09) 244 2777 ........ (08) 362 7548 Hoban . ...................... .. (002) 34 2233 Adelaide DECEMBER 1992 89 Phone Your Order To Us Toll Free We guarantee our Jetservice Courier will deliver to your door faster than any other Australian supplier (including tl')at local supplier just up the road). If we fail, I'll give you your money back plus $5.00 for your inconvenience. This great unit allows you to place calls on hold, intercom other extensions, answer calls from any extension and transfer calls. II is expandable up to 10 extensions, and is compatible with all DTMF (touch tone) telephones. Operation is as simple as pressing '*' to place a call on hold, press the extension number (0-9) and the respective station rings. Once answered, you have a two way . intercom, with which you can announce a call. To p1_ck _up the mcommg call from . hold press'#'. A neat feature is that all extensions will rmg when an mcommg call ,s placed on hold for 30 seconds so that it won't be forgotten. The Basic kit is complete with power supply, case and facilities for 3 extensions. Extra extension boards allow expansion in multiples of 3. Simple operation, fantastic for home or small off,ce. No more shouting from room to room. Not Austel Approved. _ lil'I"-•.••~ K 1430 Basic Kit $189.oo K 1435 Expansion Board $79.95 3½ Digit LCD Pan I et r Kit (S.C. Sept '92) ddition to power supplies, , current meters etc. It ea ted to accurately read 2m Requires 9 volt power sup mmable decimal point. (SC June/ July '92) This multi-station headset intercom is designed to provide clear communication in high noise environments such as at race tracks and rock concerts. It Is designed to operate with a headphone and mic combination. Each headset requires a station module. Stations are simply connected in a daisy-chain fashion. Up to 12 units (stations) can operate from the power supply. Features low noise circuitry and compares favourably to many commercial equivalents. Mics can be switched on continuously at one time for hands free operation of all stations. Also includes visual and audio call function. Ideally suited to our C 9055 headset/mic and the C 9070 noise attenuating Aviation Headset. K 5250 Station Module $7 4.95, K 5255 Power Supply $64.95 Ni-Cad Battery Discharger Kit Designed to rid your nicad batteries of the 'memory effect' . power tools and regain full recharge including drills ..potential. It discharges your ' 1(1 ' nicads correctly to enable a full recharge. Suits most battery suitable for brushpacks. Great for mobile phones, type tools up to SA. battery drills, toys etc. Not suitable for K globes or radiator 1640 95 _ _ _ _ _ _ _ _ _ _ _,__ _._h_e_a_te_r_s_._ _ __ NE ~~;r~v!::'!tc. KIT! ---------------"----------...------- $24. Four Digit Combir,.~tlon Lock Kit Get an amazing bass improvement from your stereo system. This fantastic adaptor simply "samples" your stereo amp output and provides a single channel output to feed a separate subwoofer amp. Requires 12V AC or M 9020 plugpack. K 5580 .95 $29 Drill Speed Controller Kit 1 l~~ab~!~ p;;J controller for 240V (SC Dec '90) K 1925 $44.so This 4 Digit Combination Lock is bound to prove useful in many applications. Such as accessing alarm systems, electronic doors, ignition -~·,-· . killers or just about anything that comes to mind. Momentary or latched relay output. tlve Crossov (E.A. Jan '92) This great new kit enables you to customize your sound system in your car or at home. The circuit simply connects between the audio source and the amplifiers. There are two outputs, one for bass and another provides signal for the upper range. us each amp ,s dedicated to a frequency range (i.e. one for bass, one for midrange and treble). Because no passive crossover is required in the speaker one per channel is required. Operates on+ and -15V rails. The result is a much better sound with less distortion. Door Strike Apo/ogle. In September & October ads we incoreclly advertised a K 3301 Power Supply Option for $4.50. This should read $29.50. AL TRON/CS apologises for the inconvenience. Ideal for security access areas, this high quality lock will fit most door jams. Operates from 12V AC or DC. Ideally suited to K 1925 Combo Lock Kit. s 4390 $39.95 High Power Amplifier Modules Kit (SC Dec '87) All components, including output transistors mount on a single PCB. Suitable for high quality guitar amp, public address or in a high fidelity stereo amplifier. Kit includes angled heatsink bracket, main heatsink and a in-built polyswitch for loudspeaker protection. Full specs available on request. $ $6~ NOW ONLY 55.oo K 5150 150W Version $98,{s NOW ONLY $85.oo K 5140 100W Version Megohm Me.ter Kit (EA May '89) LED Dlgital Tacho Kit $19 .95 Checks electrical wiri~g and appliances for ---..;.----------------------,-------4 insulation breakdown by passing high voltage K 5570 ltimeter for Gliders (SC Aug '91) This digital tachometer will tell you how many revs your car's engine is doing. It works with all ignition systems and 4, 6 and 8 cylinder cars. Indicates that 09900 RPM with a resolution of 100 RPM. PCB only. $31 (selectable 500 or 1000V) at low current through the test appliance. Includes calibrated megohms scale. Great for checking transformers, wiring etc Requires 6 AA batteries (not included). . est K 2555 $79 .oo our a,gg -1, seI1ing K• · K 4320 Ideal for experimenting and prototyping with Memory, Logic and Op Amps FHturea: Adjustable+ or - 18.SV at 1.7A, volt , meter, floating ground, dropout indicator, : load switch, compact sturdy "ABS" instrument case K 3325 .00 $S 9 :_ . .. :,~"": ·- ._ B . ,: . ~ : ; , " . -. .00 ow In ••nice lhrougho Inc ude Unlrer,111••• R••••rch E• Get 240V AC from your car, truck or boat battery. The AUronics ran_ge includes an inverter for nearly every appllcatron. Fantastic for camping, boating, farms and anywhere else 240V AC isn't available. Each size inverter is available in kit form or fully built and tested. The 300 and 600 Watt Famous Labtech 20 Oscilloscope Inverters now feature new improved circuitry using multiple mosfet outputs This model Is a dual trace 20MHz oscilloscope using a high brightness CRT. The vertical amplifiers have high sensitivity of 5mV/div and ,' . i a frequency characteristic response with smooth roll off exceeding 20MHz. The TV sync signal operator circuit is provided to ensure stable observation of video signals. Triggering is obtained by sampling the AC power waveform, external waveform or internally generated trigger. making them even more reliable with a genuine 300 or 600 watt continuous power rating. Our latest model, the 1200 Watt Powerhouse offers excellent value for money and performance. It features crystal locked circuitry and a massive 2400 watt power surge making it ideal for small fridges, vacuum cleaners, power tools etc. Any model an absolute necessity where 240V isn't available. Call Altronlco today for more information on freecall 008 999 007 . lJ 300 Watt K 6750 Kit Version $279 K 6755 Built-up $37 9 Ideally suited to Q 0156 (2 required) . Superb quality DC to 80 MHz Max 600 Volts DC Lead length pprox 1.5m. 600 Watt 1200 Watt K 6790 Kit Version $7 K 6792 Built-up 12V I 1 Turn 12V DC to 240V AC. This fantastic inverter will power lights, TV's tools, electric shavers and a whole host of othlar appliances. Great for camping, out in the bush and any place where 240V is not available. Featureo: Complete with over current circuit breaker • Fused 240V output • Built in panel meter to monitor output voltag_e • panel meter to monitor output voltage • Strong steel case and chassis $ . M~~ 9 This fully featured meter offers performance and facilities which are normally only found on far more expensive meters . Features include DC and AC V, DC and AC current (up to 10A), transistor check, capacitance check (up to 20uF), resistance and continuity, frequency count, temperature via optional thermocouple (' C or ' F) and high impact case just to mention a few . a 1272 20MHz Logic Probe $37.so - i.f.P1'"••<,..l ;::.~ (···:.:'..;~t.. ·.:- · Now you can solder anywhere with this new gas soldering ir~n. Feature•: See through gas chamber (no more guessing how much gas 1s left) • Built in ignition cap• Uses standard bu_tane_ gas • Comes with _safety ban.eh stand • Supplied with 2mm soldering tip and blow torch tip• Adjustable temperature from 400°C to 1200' C ~ Can be easily refilled with standard I butane lighter gas • Replacement tips are less than half pnce of some other brands . T 2455 Exhaust Port $6.50 REPLACEMENT TIPS - ALL $6.00 H T 2451 Replacement 1mm Conical Tip T 2456 Hot Kn ife Tip $6.00 T 2452 Replacement 2mm Conical Tip T 2453 Replacement 3mm Conical Tip T 2454 Replacement 3mm Chisel Tip T 2457 Hot Blower Tip $12.50 T 2458 Blow Torch Tip $12.50 T 2448 Butane Gas Refill $6.95 Car Voltage Adaptor Sealed Lead Acid Batteries As used in security systems, battery backup for computers, solar power systems etc. ... Premium Grade Long Life S 5069 S 5070 ' •• ~ , ~~ <''~s~,;s,ni::t li<t1« " ' 12V/4AH 12V/6.5AH $49.95 $54.95 1 .....-=·_ Our Top Selling Digital Multimeter ~ .. ~1 With quality and features you would expect only on ex pensive meters the Q 1056 represents excellent value for money . 17 Ranges include DC and AC volts, resistance , diode check , DC current with 1.5V and 9V battery check. ~ ~ ~·t· Iii) 1 ~. ';I-. ';i' a 1056 t49_95 -~ -.a 1057 Carry Case To Suit $12.50 Super Small PIR inbuilt sealed lead acid battery even when the mains has failed . Ideal for use Triggering which virtually dibiY \ 1 eliminates false alarms . 1nc<~ Operates on 8-16V DC. onlY 5 Features: walk test LED , wide 12x12m detection, N.C. S 5302 Normally ~ 0 0 M 9090 $69.95 This Month $69.oo Siren Cover WeatherprQof Horn Speaker Protects external siren from tampering, weather etc. Also ideal for 10 watt, 8 ohm . Ideally suited to S 5460 siren mounting strobe. cover and our alarm panels. This horn can deliver in excess of 120dB S 5460 $28.95 S 5160 Tamper Switch $1.85 High Energy Siren applications or alarm systems. Dlmenolono: 100mm Diam . 125mm L. Normally $~95 when driven by an appropriate driver circuit. C 2015 Normally$~ , This Month $ 12 .95 Alarm Strobes Absolutely ear splitting SPL 120dB. Handy bracket for wall mounting etc. 12V 300mA. Ideal for industrial s 5177 mall! Incorporates Pulse Count tamper switch, interfaces with most alarm panels. See AL TRON/CS '92 catalogue for full details. with alarm system power supplies monitoring systems , warning systems etc. Suits C 2015 horn speaker. Tamper switch available . This handy unit simply plugs into your car's cigarette lighter socket and presto! Gives you switchable 3, 4.5, 6, 7.5, 9 and 12V DC at up to 800mA. Includes a range o( output plugs. Reversable polarity. Great for pocket TVs, M 8150 $16.95 radios, portable CDs etc. 1280 50MHz Logic Probe Pulser $54.95 With stylish compact good looks this alarm blends smoothly into any residential or office decor by either flush mounting into the wall , or surface mount. 3 secto'rs include 24 hour panic / fire , perimeter and internal which can be isolated enabling the alarm to be armed at night with occupants inside whilst still protectmg entries. Simple 4 digit access code for operation . See Altron1cs '92 catalogue for full details. S $119.oo 5490 This UPS (Uninterruptable Power Supply) will supply 12V at 1.2 Amps via its internal T 2449 $39.s5 Q (! ~ 24 NIMROD Gas Soldering Iron 12V/ 1.2AH Digital Engineering Multimeter compatibility. Deluxe version includes a logic pulser function making it even more versatile for fault finding, and a 50Hz logic probe. Economy version includes 20MHz logic probe only. a1064t149.5o Q 1065 Carry Case to Suit $12.50 Q 1067 Thermocouple to Suit $29.95 300 Watt Economy Inverter S 5065 Two models available. Both feature audio and ~-------------"----'"1 visual 'hi ' and 'low' indication, and TTL/ CMOS K 6770 Kit Version $499 K 6774 Built-up 12V Input $62 K 6775 Built-up 24V Input $25.oo Uses Xenon Strobe tube for high energy flash . Output rate approx 1 per second . 12V DC, 320mA. Dimensions : 97mm diam , 50mm High . S 5455 Blue S 5450 Red~5 Now $20 .00 111 111 fr mazing Nlcad Battery Bargain 2.oo At full specification premium quality. Good for up to 1000 recharges. S S S 5020 5022 5023 1-9 10-24 $2.so $7.oo $13.oo $2.95 AA 500 MAH 'C' 1.8 AH 'D' 4 AH $8.oo $14.oo 25+ $2.oo $6.oo $12.oo Passive Infra-Red Flood Light Control ~~~~~~rvf~~o r~~::r~h~1rin1:i~!r~ 8 A •iili!:•• $18 9.00 $19.so C 9075 Carry Case To Suit A Converts sockets into a double socket to allow you to plug in two phones . frequency response 1.BkHz to 30kHz and C 6160 $39.95 These Poly Emulsion Coated Cone (PEGG) Speakers utilize the development of high grade driver components in Japan, such as Barium ferrite magnets and specially formulated paper cones impregnated with poly emulsion. The result is a driver of quite remarkable power handling, performance and extremely low distortion . C 3024 ~ Now $54.95 174 Roe St. Perth W.A. 6000 Phone (09) 328 1599 PHONE TOLL FREE 008 999 007 MAIL ORDERS C/ - P.O. Box 8350 Stirling Street PERTH W.A. 6849 P . 0995 $4 .95 H gh Pe n ay Flush Mounting full Rang 60W Speaker Sy speakers to install. Designed to 1000 $& 9.95 install into ,ve $$• on ceilings or 12" Guitar Sequivalent walls this Building that extension ? What great Speaker SPL at 93dB (2.83v/ 1m). 91 x 91mm mounting hole centres. Specifications available on request. Simply wires in parallel to your woofer. No crossover or capacitor required . As it presents almost no load to your amp it doesn 't effect the overa.1I speaker system 's impedance. Fantastic for hi-fi or disco speakers. e 0492 $119.95 This universal infra-red remote control makes all • • • other remote units superfluous. Will control ....;;. .. CD players, videos, TV's • • • • and stereos etc. :::: Controls up to 6 •••• different appliances. ,;,,.,.,. .. Easy to use and -• ••~ programme from an a;. existing functional remote High performance Series II. Features• Noise attenuating earphones • Noise cancelling mic • Sturdy construction • Cushioned head pad • Includes standard aircraft jacks • Over 4000 sold Australia wide • Don't pay $400 or more! Genuine Motorola KSN 1165A. Features 400 watt maximum power capability $17 .95 $19.95 __ A 0493 Optional Remote $24.95 4 9 95 1 ersal Remote Telepho 0 e Ideal fo-r answering Ada t machine Control and phone Altronics Aviation Headset tweeter looks and sounds great. J Telecom approved FHlu,.a: Variable length outgoing message (maximum 30 seconds • Security code access for remote • Cail screening• 12 month replacement guarantee • Optional Full function DTMF Remote Control for Playback, Reset, Save, Outgoing Message change. or even to find the keys in the dark! Features daylight sensing circuit which means unit will not activate during daylight hours (save on your power bill). Includes manual override facility to turn lights on continuously or automatically. Features movement sensitivity adjustment. and turn on period. Great for the driveway or backyard. Complete with two screw in type sockets for standard 150W floodlight globes (not included). This new bullet M9005 6, 9. 12v<at> 500mA $pl'50 Telephone Answering Mac Just arrived, this new model PIA floodlight activates when it detects movement of a C 9070 Headset -DC' These multi-purpose AC-DC adapters are Just great for toys, calculators, radios, etc ■ etc Both include a range of output , voltages, a range of plugs reversible polarity and are energy authority --approved ,- M 9000 3, 4 5, 6, 7 5, 9, 12V <at> 300mA $),0"95 replacement ,aker 50 Walla RMS, 100 Watts Max. Attention all guitarists and keyboard musicians. This fine USA design~d speaker is supplied as standard equipment to the world famous brand name series of Guitar Amps. • Impedance: 8 Ohm • Sensitivity: 101dB/W (0.5m) • Weight: 2400gm C 3102 Normally $j8'oo This Month s' · 89.oo slim profile attractive speaker system/ grille assembly will compliment any sound system. Once installed the . finished unit Front Grille Not Illustrated blends beautifull y into any decor. (The grille assembly can be painted over in the same finish as walls or ceilings if required). Installation is simplified by the use of a mounting frame (which could be installed during construction) which the speaker assembly attaches to. Full mounting kit (even screws) supplied. C 0880/C 0855 Normally~O This Month $219.oo per pair HEAVY HEAVY SERVICE - All orders of 10Kgs or more must travel Express Road Please allow 7 days for delivery. $12.00 to 10Kgs. $15.00 over 10Kgs. INSURANCE - As with virtually every other Australian supplier, we send goods at consignees risk. Should you require comprehensive insurance cover against loss or damage please add $1.00 per $100 of order value (minimum charge $1 ). When phone ordering please request '' Insurance" TOLL FREE PHONE ORDER - Bankcard , Visa, Mastercard Holders can phone order toll free up to 6pm Eastern Standard Time. Remember with our Overnight JelM rvfce we deliver next day. STANDARD DELIVERY I PACKING CHARGE $3.50 to 500gms, $5.50 500gms- 1Kg, $8 ·IKg-5Kg AUSTRALIA WIDE - We process your order the day received and despatch via. AL TRON IC RESELLERS Chances are there is an Altronic Reseller right near Australia Post. Allow approx 9 days from day you post order to when you receive goods . you - check this list or phone us for details of the nearest dealer. OVERNIGHT JETSERVICE Up to 3Kg is $10.00, 3Kg to 5Kg is $23.00 - We process your Blue Ribbon Dealers are highli~hted with a ■ These dealers general ly carr y a orderthe day received and despatch via . OvernlghtJetMrvfce Courier for delivery next day comprehensive range of Altron1c products and kits or will order an y requ i red item for Country areas please allow additional 24-48 hours. you . WA COUNTRY ALBANY BP Electronics ■ (098) 412681 Micro Electronics (098) 412077 BUNBURY Micro Electronics (097) 216222 ESPERANCE Esperance Communications (090) 713344 MANDURAH Lance Rock Retravision (09) 535 1246 PORT HEDLAND Ivan Tomek Electronics (091) 732531 ROCKINGHAM TV Joe's (09) 5271806 T ALICE SPRINGS Farmer Electronics (089) 522388 DARWIN Ventronics (089) 853 622 All Electronic Components (03) 6623506, TECS (03) 6706474 BORONIA Ray Cross Electronics ■ (03) 7622422 CHELTENHAM Talking Electronics (03) 5842386 COLLINGWOOD Truscott Electronics (03) 4198208 CROYDON Truscott Electronics ■ (03) 7233860 FOOTSCRAY G.B. Telespares (03) 3179100 PRESTON Preston Electronics ■ (03) 4840191 COUNTRY BAIRNSDALE LH & LM Crawford (051) 525677 BALLARAT Ballarat Electronics (053) 311947 OLD Delsound PL ■ (07) 8396155 WEST END B.A.S. Audiotronics (07) 8447566 WOODRIDGE David Hall Electronics ■ (07) 8082777 COUNTRY GLADSTONE Gladstone Electron ic Services (079) 724459, Electronic Enterprises (079) 726660 MAROOCHYDORE MALS Electronics ■ (074) 436119 MARYBOROUGH Keller Electronics (071) 214559 NAM BOUR Nambour Electronics (074) 411966 PIALBA Keller Electronics (071) 283749 ROCKHAMPTON Access Electronics (East St.) (079) 221058 TOWNSVILLE Super Soiex ■ (077) 724466 '>A Force El ectronics ■ (08) 2125505 BRIGHTON Force Electronics ■ (08) 3770512 CHRISTIE$ BEACH Force Electronics ■ (08) 3823366 FINDON Force Electronics ■ (08) 3471188 HOLDEN HILL Force Electronics ■ (08) 2617088 LONSDALE Force Electronics ■ (08) 3260901 ENFIELD Aztronics ■ (08) 3496340 COUNTRY WHY ALLA Eyre Electronics (086) 454764 TAS HOBART George Harvey ■ (002) 342233 LAUNCESTON George Harvey ■ (003) 316533 N W David Reid Electronics ■ (02) 2671385 REVESBY Revesby Electronics (02 ) 7738087 SMITHFIELD Chantronics (02 ) 6097218 COUNTRY COFFS HARBOUR Coifs Habour Electronics (066) 525684 NEWCASTLE Novocastrian Elect .Supplies (049) 621358 WARNERS BAY Vi lec Distributors (049) 489405 WINDSOR M & E Elect. and Communications (045) 775935 WOLLONGONG Newtek Electronics ■ (042) 271620, Vimcom Electronics (042) 284400 WOY WOY Alphatran Electronics (043) 434919 Ple ■oe note that all care has been taken In preperatlon of theM ado, however AL TRON/CS la not liable for errors, typographical or otherwise. I PRODUCT SHOWCASE I Zenology Sales Pty Ltd, 7/245 Springvale Rd, Glen Waverley, Vic 3150. Phone (03) 802 0599. New satellite receiver from Av-Comm Multimeter with PC interconnect A new range of digital multimeters has been released by Levell Electronics (UK) Ltd. The top of the range model VC96 can be linked to a PC via an infrared RS232c link. The VC96 is an autoranging 3¾-digit multimeter with a bargraph display. It can provide measurements of AC/DC amps and volts, resistance, frequency, capacitance and transistor gain. It also features a diode/continuity test range and meets IEC 348 class II. Maximum, minimum and average reading storage is provided, as well as a data hold and relative mode function. The VC96 multimeter and the infrared link combine to produce a versatile low cost datalogger. The infrared link is quick to set up and there is no socket on the multimeter to get damaged. To operate the link, you simply slip the VC96 into the VCIR sleeve, and load the custom software. The VCIR software allows storage of up to 250 hours of information. It provides graphical and digital displays, calculates decibels and audio power, and runs under MS DOS with a Hercules, CGA or VGA display. Options include a protective holster and stand. For further information, contact ~MTI~~tro POTTER &BRUMFIELD RKS-SDG-12 10A 250V f\U OR 30VDC 1/3HP 250VAC 360VA 240VAC O* • I Av-Comm Pty Ltd has announced the introduction of a new 100-channel PAL satellite receiver, suitable for use on either the C or K bands. The new receiver has extended 9501750MHz block down conversion and boasts a comprehensive range of user controls and features accessible via an infrared remote control. These include on-screen display, PLL synthesised tuning, dynamic noise reduction, programmable channel selection, decoder output switching, scan and selectable half transponder reception. The unit has discrete audio and video outputs using either SCART or RCA connectors, and provides a tuneable UHF output with an in-built test signal for direct connection to a TV set. The receiver supports mechanical and magnetic polarisers, and has an AFC system capable of tracking several megahertz of LNB drift. For more information, contact AvComm Pty Ltd, PO Box 225, Balgowlah NSW 2093. Phone (02) 949 7417. Free desk clocks with floppy discs Verbatim is giving away desk clocks valued at $65.00 as part of this year's ll®<at><at>[}{] <at> ~[}{]~lY□□ POTTER & BRUMFIELD {SIEMENS) PCB RELAYS SERIES RKS-SPDT-1 0A-250VAC-SEALED-WASHABLE orM<at>M~u!XlW ~u/ijfM<at>fij!XJ<at> ~o:J!g &½ ffeJOrM<at>Mu $1.99ea (100 up) PLUS SALES TAX IF APPLICABLE Reserve Electronics Pty. Ltd. ACN 008 822 455 SYDNEY 02 9068486 MELBOURNE 03 6652536 PERTH 09 3289755 DECEMBER 1992 93 Christmas promotion of its PC storage products. Five boxes of Verbatim Datalife or Datalife Plus floppy discs, or five Verbatim Data Cartridges, must be purchased to qualify for the clock. The data cartridges are in 0.25-inch, 4mm and 8mm sizes. On each pack of discs or data cartridges is a coupcn. Purchasers must collect five coupons and may apply as many times as they like. The offer is available from participating dealers until December 31, 1992 or until stocks last. To redeem the offer, customers must apply to Verbatim by last mail, . January 31 1993. For further information on the Verbatim range of computer products, contact Verbatim Australia Pty Ltd, 42 River St, South Yarra, Vic 3141. Phone (03) 827 1361. cally set, irrespective of input signal amplitude or waveform, thus eliminating errors due to incorrect trigger Universal frequency settings. counter from Philips Standard bandwidth is DC 300MHz, while a choice of optional Philips has introduced the PM6685 frequency counter, a calibration labo- RF inputs extends the bandwidth to 1.3GHz, 2.7GHz or 4.5GHz, the latter ratory standard instrument that's fully portable. The PM6685 offers a resolu- being the highest prescaler input fretion of 10 digits for a 1-second update quency available in any portable fretime, a DC-300MHz standard band- quency counter. This particular input width (up to 4.5 GHz optional), and is designed around a proprietary GaAs timebase stabilities up to five parts in chipset. 10 10 over a 24-hour period. The high resolution of 10 digits also Philips claim that this is best meas- applies to the optional RF input chanuring performance available in any nels. In systems or GPIB-cluster portable frequency counter. It is also applications, the PM6685 can store easy to operate due to microprocessor up to 1600 medium resolution (5 digit) control of input trigger settings in re- measurements per second in internal sponse to varying input signals. The memory. Dual displays allow simultaneous optimum noise immunity is automati- readings of frequency and signal level, while a 3dB/segment analog bargraph gives confirmation of adequate signal level, eliminating the need to check signal levels with a separate instrument. For further information, contact Philips Test & Measurement Division, 25-27 Paul St North, North Ryde NSW 2113. Phone (02) 888 8222. VGA buffer has 10 outputs This unusual buffer allows a personal computer to drive up to 10 VGA monitors. It is intended for use in schools and universities, and for factory process displays and exhibitions. The U-Sync Buffer measures 330mm wide, 70mm high and 235mm IAN J. TRUSCOTT'S ELECTRONIC WORLD 30 Lacey Street, Croydon, 3136. Phone (03) 723 3344; Fax: (03) 725 9443. Mail & Credit Card Orders Welcome We stock an extensive range of semiconductors, FETs &Mosfets, power &zener diodes, SCRs, Triacs, Linear ICs, 74LS/HC & 4000 series ICs, high-intensity LEDs and displays. Accessories inc. pots, trimpots, RF chokes, voltage regulators, relays, fuses, globes & heatsinks, as well as a comprehensive range of popular switches, knobs, plugs & sockets. We offer a huge range of resistors, capacitors & popular parts at competitive prices. Rechargeable batteries, incl. regular, tabbed, rapid charge & back-up types are available ex stock. Ring for a price on our sealed leadacid, video , cellular phone & watch batteries. 94 SILICON CHIP We now offer a speedy, courier delivered, mail order service. HI-FI & PA SPEAKERS Huge variety of all common hi-fi replacement speakers, crossovers, speaker cloth & grilles. Call for a price on our great range of speakers, microphones, cables, audio leads & adaptors. We'll send you a catalogue. 2-way crossovers (pair) from 3-way crossovers (pair) from SWF12 12" 100 watt RMS woofer SWF8 8" 60 watt RMS woofer Redford PECC 6.5" 60 watt woofer Redford PECC 12" 160 watt woofer $9 $16 $75 $39 $38 $114 DM40 4" 50 watt RMS midrange DT30 1" 35 watt RMS dome tweeter Ferro Fluid 30 watt (60 max) tweeter Piezo tweeters from Speaker wall mounts from 2-way speaker switch boxes 3-way speaker switch box (impedance matching) $16 $11 $13 $16 $39 $18 $49 Don't forget our disposals store at Sth. Croydon. There's plenty of hard-to-find parts and help you won't get elsewhere! Phone 723 2699 (ask for Mai) First High-Speed IEEE 488.2 Controller for Notebook PCs deep and can be powered from 100-135VAC or 200275VAC. It accepts standard VGA analog signals and has a minimum video bandwidth of 120MHz at -3dB. It is claimed to drive VGA monitors up to 75 metres away from the unit. The VGA connector sockets are 15-pin D subminiature types. Recommended retail price is $795 from Rod Irving Electronics, 74 Parramatta Rd, Stanmore, NSW 2048 and other stores in Melbourne, Sydney and Adelaide. Vintage radio calendar shows famous brands Vintage radio enthusiasts will be interested in a 1993 calendar devoted to fine examples of the hobby. Thirteen excellent colour prints of famous Australian mantel radios are featured, along with a brief history of each model. If you have one of the models in question, these photos would certainly answer any questions you might have regarding their finish and presen_tation. The calendar is available for $18.95 plus $2 postage from Resurrection Radio, 51 Chapel St, \'\:indsor, Vic 3181. Phone (03) 529 5639. Barcode decoder IC from Hewlett Packard Hewlett Packard has introduced a barcode decoder integrated circuit that eliminates the need for a separate memory chip and supporting circuitry. While providing a superset of the capabilities of HP's popular HBCR18XX series decoder IC, the HBCR-161X series reduces the number of ICs needed for a barcode reader. The HBCR-161X IC can be used with contact type readers such as digital wands and slot readers. The HBCR-161X can be used in data collection and point of sale terminals, keyboards, weighing scales, medical equipment, test instrumentation, materials handling equipment and other systems that have data collection needs. The chip decodes most popular bar codes used for industrial, medical, service, government and retail point of sale applications. ► IOtech The Personal488/NB is a compact external IEEE 488.2 interface that enables 170 Kbyte/s IEEE 488.22 control of up to fourteen IEEE instruments from a notebook PC via its parallel port. A virtual PC plug-in board in terms of speed and performance, the Personal488/NB is compatible with both IOtech 's DLL driver for Microsoft Windows and with its DOS subroutinestyle and device driver software. The Personal488/NB also supports third-party data acquisition software packages, such as DADiSP and Labtech Notebook. The Personal488/NB uses FPGA (field programmable gate array) technology to permit simultaneous instrument-control and printer transactions via its connection to a notebook PC 's parallel port. The unit can draw power from a notebook PC's keyboard port, a 7 to 15 VDC voltage source, or a standard A/ C voltage source via an included power supply. Portable and Remote Applications. As notebook PCs decrease in price and increase in functionality and power, many engineers are finding them practical, easily transportable alternatives to cumbersome desktop PCs. The Personal488/NB enables engineers to use notebook PCs in IEEE instrument control and data acquisition. It is well suited for vehicle testing, such as aircraft and automobile testing, where physical space is at a premium, and is also ideal for users who require a portable computer, such as test-instrument sales engineers, who can now use notebook PCs to demonstrate IEEE 488 instruments on customer calls. The Personal488/NB is also useful for engineers who need to analyse acquired data away from the test site because it enables the same notebook PC to be used both on-site for data acquisition, and in the lab for subsequent data analysis. This eliminates the time-consuming data transfer processes and cross-platform incompatibility problems sometimes associated with using one desktop PC for testing and another for analysis. SCIENTIFIC DEVICES AUSTRALIA PTY LTD r;.1 Melbourne Fax Sydney Fax Adelaide Fax (03) (03) (02) (02) (08) (08) 579 3622 579 0971 344 5200 349 2602 281 3788 281 4194 Product names listed are trademarks of their respective manufacturers' company. DECEMBER 1992 95 Other features include data input at up to 76cm/s, bidirectional scanning, support for parallel or full duplex serial communications at up to '9,600 baud with a choice of parity and stop bits, and support for audio and visual feedback to the user. Operation is from 5V DC, requiring a maximum of 24mA at a maximum clock rate of 16MHz and 6mA while idling. For further information contact, VSI Promark Electronics, PO Box 578, Crows Nest, NSW 2065. Phone (02) 439 8622. High density 9-track drives Overland Data Inc has introduced 1Ls new Tape-Pro series of ultra-compact high density (6250 bpi) 9-track tape drives. These allow users to ex- High temperature electrolytic capacitors Siemens now has available a range of aluminium electrolytic capacitors intended for high ambient temperatures of up to 105°C. Envisaged mainly for the stringent conditions of automotive use, the B41538 range is characterised by a long lifespan. Siemens claim that this will ensure the reliability of airbag and xenon vapour pressure lamp systems in cars. Can sizes of the new electrolytic capacitors change data stored on 9-track tape among mid-range and mainframe computers, PCs and UNIX-based workstations. The new drives are 9cm high, weigh under 14kg and can sit on a desktop or can be mounted in a rack for computer room use. They support Pertee/ Cipher plus interfacing, a feature exclu,sive to Overland Data, whereas the 5000 Series drives support Pertee/ Cipher, parallel port and SCSI. Data compression is provided with vary from 18 x 30mm to 25 x 40mm. For further details, contact Siemens Ltd, 544 Church St, Richmond, Vic 3121. Phone (03) 420 7716. the SCSI models, to increase capacity by 2-5 times, depending on the type of data stored. One megabyte of cache memory is provided with Tape-Pro drives. The combination of caching and tape speed optimisation ensures maximum data transfer performance and eliminates CPU and disc drive delays. For further information, contact Elmeasco Instruments Pty Ltd, PO Box 30, Concord, NSW 2137. Phone (02) 736 2888. SC THE 1993 GOSFORD FIELD DAY FOR RADIO AMATEURS AND ENTHUSIASTS, COMPUTER AND ELECTRONIC HOBBIESTS SUNDAY 28TH FEBRUARY 1993 AT THE WYONG RACECOURSE - GATES OPEN 8AM • Truckloads of pre-loved equipment at give away prices in the fleamarket and disposals areas. • See all major Amateur Radio equipment suppliers together under one roof with many dealers displaying the latest products and offering once in a year bargain prices. • Interesting technical lectures • Packet Radio - Computerised Communications Displays. • Radio fox hunts. • Amateur television transmission 'displays. • Entrance fee only $6.00. Pensioner concession $3.00. Senior card $5.00. Children under 12 free. • Free off street parking. • Free sightseeing tour of the Central Coast. • Free entry tickets to the Australian Reptile Park. • Bring your picnic lunch or buy hot and cold food and drink from the stalls in the grounds. DON'T MISS THE BIGGEST FIELD DAY IN THE SOUTHERN HEMISPHERE Presented since 1957 by the CENTRAL COAST AMATEUR RADIO CLUB INC. For further information write to the CCARC PO Box 252 GOSFORD 2250 96 SILICON CHIP ANTRIM TOROIDAL TRANSFORMERS ---=-K""°~- IN ANYONE'S LANGUAGE. PROCON TECHNOLOGY LETS YOU TAKE CONTROL! ~~~VT -~.......___..•-!.- We manufacture a wide range oflow-cost digital 1/0 boards. Each board features: 8 opto-isolated inputs (12/24/48V AC or DC), 8 relay outputs (switching up to 10 Amps at 250VAC), LEDs indicate 1/0 status and IBM-PC software is included. An industrial version with plug-in relays is also available. The system features: External mounting (up to 30 metres from computer) operating through any IBM-PC bi-directional printer port and capable of expanding to 240 1/0. Applications: Home or business security systems, process monitoring and control, laboratory automation, quality control testing, robot control and energy ·management. • Now made in Australia. • Standard range 15VA to 2kVA. • Large ex-stock quantities available. • Competitive pricing available for OEMs & resellers. • Simply the best transformers all round. HARBUCH ELECTRONICS PTY LID 90 George Street, Hornsby NSW 2077. Telephone (02) 476 5854. Fax (02) 476 3231. PHOCONtechnologn ~~!11 ~ Box 655, Mt. Waverley, VIC. 3149. IIIIUIIIFIM,_.IS&m.111a TEL: (03) 807 5660 FAX: (03) 807 8220 • Yes! High-speed drivers are available for GWBASIC, QuickBASIC, TurboBASIC, QuickC, TurboC and TurboPascal. Our file 1/0 driver also allows many other programs and languages to be used. E.g. DBASE, Clipper, COBOL, FORTRAN, MODUIA-2 etc. ON SALE NOW First edition Vintage Radio Calendar, in full colour. Featuring a selection of Australia's most photogenic radios. Ideal Christmas gift for friends and collectors overseas. Available from Resurrection Radi CREDIT CARDS ACCEPTED 51 CHAPEL STREET, WINDSOR, VIC. 3181. PHONE (03) 529 5639. DECEMBER 1992 97 ASK SILICON CHIP Got a technical problem? Can't understand a piece of jargon or some technical principle? Drop us a line and we'll answer your question. Write to: Ask Silicon Chip, PO Box 139, Collaroy Beach, NSW 2097. Controllers for model railroads The problem I have is that when building controllers for my son's model railway I have been using a lkQ or 2kQ pot to control from 0 to 12V DC from the transformer which gives you the speed from slow to fast. This works fine, however I have forgotten which type of pot it was; ie, metric linear, logarithmic, anti-log, or wirewound. I think I was using a logarithmic lkQ pot. Perhaps there is a better one to use. The output is 12V DC4A. Also, if I wanted to run more than one track from one power supply (eg, three separate tracks at the same time), would I have to go to a physically larger transformer which is heavier wound but with the same output 12V 4A? Or would I just go to a bigger transformer - say 18V 6A? (D. P., Port Pirie, SA). • We cannot nominate the type of pot you need unless we know the circuit configuration you are using. Or are you simply using a pot wired as a rheostat? If so, then the pot should be a wirewound type with a rating of Wants articles on boat electrics I wonder if you could consider doing an article on boat electrics? By that I mean a discussion on the 12V system, particularly the alternator, its exciter, its regulator, ways of dealing with more than one battery, isolating switches and isolating diodes. Having been an electronics enthusiast since about 1943, I always felt that I had a reasonable grasp of anything to do with electricity. However, since acquiring a boat with three batteries and a diesel engine recently, the depth of my ignorance on what should be a 98 SILICON CHIP several watts and probably with a value of 500Q or less. Alternatively, if you are using a conventional electronic controller similar to the circuit published in the November 1990 issue of SILICON CHIP, the pot should be a linear type. This controller will give better performance than a simple rheostat controller but, for really top performance, you should go for the Pulse Power Train Controller featured in the May 1988 issue. Unfortunately, without knowing the circuit you are using and the typical current drain of your locomotives, we cannot make any suggestions abou t the current rating of the transformer. Problems with the iron timer I recently decided to make the Iron Timer that w_as published in your August 1990 issue. In doing so, I found two faults in the published design as follows: (1). The 390Q current limiting resistor was low enough to allow an excessive current through to earth with the result that the supply voltage very simple subject has come as a bit of shock. Anything you can do to shed light in these dark places would be greatly appreciated. I do enjoy SILICON CHIP. (M. F., Frenchs Forest, NSW). • This is a subject that we have not previously contemplated featuring in the magazine. What do other readers think? If there is sufficient demand for such a series, we'll see what we can do. We can assure you on one point though . Boat and car electrics are no longer simple and are becoming more complex as time goes by, especially in cars which now have complicated computer-controlled engine management systems. fell below 4 V and prevented power cutoff. A change to lkQ fixed that problem. (2). The piezo transducer was almost inaudible. Looking into the matter, I found that this item resonated at about 4kHz. It became satisfactory when I replaced the lOkQ oscillator resistor (between pins 11 & 12 ofIC3d) with a 5kQ trimpot and tuned the circuit to resonance. In view of the above, I recommend that you make a trial run of any design before publication. (B. C., Sandringham, Vic). • We are puzzled as to why the 390Q resistor in your circuit had to be changed to lkQ in order for the circuit to work. Since the DC supply is capable of delivering about 35mA or more, it should be able to perform as stated. We suggest that you check the 0.47µF 250VAC capacitor and the 4 70Q 1W resistor in series with the bridge rectifier, as an incorrect part may have been used here. By changing the 390Q resistor to lkQ, there is a risk that the MOC3021 will not have sufficient LED current. for reliable triggering of the Triac. We also suspect that your piezo transducer's output may have been on the low side. Operating the unit at resonance will certainly increase the output but that would have required an adjustment which we regard as undesirable in a circuit of this nature. By the way, there is no connection to earth in the circuit. The earth symbol indicates the 0V rail which connects to Neutral. We normally build more than one prototype of our projects and often build several. Yours is the first complaint we have had about the Iron Timer; which is now over.two years old, so we don't believe that there are any problems with the design. Sockets & the digital sine/square generator I have purchased a kit for the Digital Sine/Square Generator featured in July and August 1990 issues of SILICON CHIP. My query is can I use sockets for all the ICs and if not, which can have sockets? (D. S., Beelbangera, NSW). • We would recommend against using sockets for the critical circuitry involved with the waveform generation as the extra capacitance of the sockets could contribute to distortion. However you could use sockets for IC5, IC7, IC12 & IC13. Avoid using cheap sockets, though. They are generally more trouble than they are worth. Questions on the sinewave inverter After reading your article on the new 2kW 24VDC To. 240VAC Sinewave Inverter, I wish to ask the following: (1). Does it have autostart/shutdown and thermal overload protection with auto-reset? (2). Can the unit be converted to operate at a higher input voltage, say 34V DC? (3). What is the price of a kit and where can I buy it? (M. P., Colac, Vic). • At present the circuit does feature thermal cutouts but does not have autostart/shutdown or auto-reset after overload. We may provide these features as an add-on board at a later stage. Unfortunately, it is not easy to change the design to accept a higher input voltage. We chose 24V as areasonable compromise between input current and versatility. Kits will be available from Rod Irving Electronics in early 1993 and this company will be able to advise on the price. Wants a fuel flow sensor Could you please advise me on where I might be able to purchase a fuel flow sensor. I would like to construct a gauge to show fuel flow in analog form. Absolute value is immaterial - only the trend is required to allow me to trim my power boat for minimum flow. I believe that a flow transducer was used in a car computer kit some years ago. (F. L., Mundingburra, Qld). • As far as we know, there is no readily available sensor in Australia. However, we have published your letter in Problem with PEP monitor I built the PEP Monitor circuit from the July 1991 issue of SILICQN CHIP but I am having problems fitting it to a Micronta 3-Range Power/Modulation/SWR Tester. I have fitted a DPDT switch ·so that the unit can be switched on or off and so that the PEP Monitor can be switched in or out of circuit. The power meter has trimpots fitted to it so that it can be switched to 5W, 50W or 500W and I suspect that this is where my problem lies. When the DPDT switch is in the normal power meter position, everything is OK. When switched to the PEP position and the meter switched to the 5W position, the meter still reads OK but when switched to the 50W or 500W position, the needle barely moves. Am I trying to fit this circuit to a the hope that one of our readers can help. PC board for the autofire module I was wondering if you or G. Cattley of Sydney, NSW could provide me with a PC board (or just the design for one) for the Autofire module published in the October edition. I have all the parts except something to assemble them on and would like some advice on what to use and how to go about the assembly if a PCB or a design is not available. (B. M., Strathfield, NSW). • Normally, PC artworks are not made available for designs published in our Circuit Notebook pages. It is likely that the designer made up this circuit on Veroboard or on prototype board. However, we have published your letter to see if other readers want the design too. If so, we will be happy to produce an artwork and publish it. Adapting US projects 240V mains operation American books often have projects to build using 120V at 60Hz but we meter which is not suitable? Also could you please advise what the PEP reading should be if the transceiver is putting out say 50W RMS. Is there a formula so that this can be calculated? Thank you for a very interesting and informative magazine. (J. C., Sturt, SA). • Your problem probably stems from the fact that you don't have full isolation between the PEP Monitor and the power tester. The PEP Monitor is intended only to drive a lmA or similar meter movement. Therefore, to make the circuit work with your power tester, you will have to isolate the meter itself and ensure that its sensitivity is of the order of lmA. The peak envelope power (PEP) is equal to the RMS power multiplied by 2. Thus, if your transmitter is putting out 50W RMS, the PEP is 100W. Note that a PEP Monitor is only really necessary if you are using SSB transmissions. have 240V at 50Hz. What do I do about it with a limited electronics knowledge, because they probably would not work on 50Hz? (D. H., Mosman, NSW) • As a general rule, American circuits can be adapted to the 240V mains simply by substituting an equivalent 240V transformer for the 120V unit originally specified. However, if the circuit relies on 60Hz for timing or synchronisation, then it often cannot be easily adapted. That said, you should steer clear of such circuits unless you know exactly what you are doing. Often, the circuits presented in books lack constructional details and this can easily lead to a dangerous situation if your knowledge of the subject is limited. Notes & errata Studio• Twin 50 Stereo Amplifier, April 1992: the 0.33µF output capacitor in the righthand channel of the phono preamplifier is incorrectly positioned on the wiring diagram (Fig.5). It should be connected between the 100Q resistor and the nearby vacant pad that runs back to the adjacent lMQ resistor. SC DECEMBER 1992 99 Index to Volume 5: January-December 1992 Features 01/92 42 Experiments For Your Games Card 01/92 82 New Blood Steriliser Uses Microwaves 02/92 6 The Mobile Telephone Revolution 02/92 69 Designing A Speed Controller For Electric Models 03/92 4 The Electronic Dentist 03/92 8 How To Adjust Your Hot Water System 03/92 70 Updating The Resistor & Capacitor Scene 04/92 6 Understanding Computer Memory 04/92 14 Yokogawa's 100MHz Digital CRO 04/92 56 The Electronic Workbench 05/92 6 We Take A Look At CD ROM 05/92 16 Computing On The Big Screen 06/92 42 SuperMac: Video Editing On the Small Screen 06/92 53 What's New In Oscilloscopes? 07/92 16 Understanding The World Of CB Radio 07/92 82 Electronics Workbench For Home Or Lab 08/92 16 The Musical Instrument Digital Interface 09/92 16 A Tutorial On PC-Based Data Acquisition 10/92 4 Manned Electric Flight Across The USA 10/92 73 The Philips PM3394 Digital/ Analog Scope 11 /92 6 A Brief Look At Liquid Crystal Displays 11/92 32 The Oriel : Jamo's Flagship Loudspeaker System 12/92 8 Ten Years Of The Compact Disc 12/92 64 High Voltage Probes: Beware The Dangers Serviceman's Log 01/92 34 AWA Mitsubishi C-3423; CT-144 7AM/CT-1440A 02/92 56 Rank Arena C-2053; Hitachi Fujian HFC-1425B 03/92 54 VCRs: Sharp VC-9300X; Sharp VC-782X; National Panasonic NV-850 04/92 36 Samsung CB5012Z TV Set; Sony KV1830 TV Set 05/92 40 Panasonic TC-2969 TV Set; AWA SC5326 Q Chassis (TV Set) 100 SILICON CHIP 06/92 36 Samsung CB5025 TV Set; Panasonic TC-1401 AR TV Set 07/92 40 Sharp GF-76002 Stereo Radio Cassette; Akai VS-112EA VCR 08/92 40 General GC-202 TV Set; Sharp VC9300X VCR 09/92 64 English Thorn 9418 TV Set 10/92 42 Panasonic TC-2969 & TC-48R60 TV Set 11 /92 44 Telephone Answering Machine; "Magic" Computer 12/92 84 Kriesler 59-1 TV Set; Rank Arena C2601 TV Set TETIA TV Tips 01/92 37 Princess 14CT8 (PC-02X Chassis) 02/92 57 Sony KV2764EC TV Set 03/92 54 AWAC620 (G Chassis) TV Set 05/92 41 Samsung TV Chassis No. P50F & RM101 06/92 40 AWAAV11 Video Recorder 07/92 43 JVC HR-7200 Video Recorder 08/92 43 Sharp DV4884 TV Set 09/92 67 AWA C2341 TV Set 10/92 45 Akai CT-K209 TV Set 11/92 47 Akai VS-4E Video Recorder 12/92 89 Sanyo 83P Chassis (TV Set) Computer Bits 01 /92 40 What To Do When Things Go Wrong 02/92 50 More Things To Do When Things Go Wrong 03/92 52 Coping With Damaged Directories & File Allocation Errors 05/92 24 The PC Game Is Changing Again - OS/2 Is Really Here 06/92 32 A Look At Hard Disc Drives 07/92 70 Good Books On The PC Can Be Well Worthwhile 09/92 37 The 68705 Microcontroller 10/92 92 The Inside Story On Hard Disc Standards 11 /92 88 The PHd Pocket Hard Disc Drive 12/92 28 Upgrading An AT Computer To a 386DX Motherboard Amateur Radio 01/92 74 The Global Positioning System 02/92 72 A Look At Trunked Radio Communications 03/92 50 The AR-1500 & AR-2800 Scanning Receivers 04/92 42 Receiving Weather Satellite Signals - The Hardware Required, Pt.1 05/92 86 Receiving Weather Satellite Signals, Pt.2 07/92 72 Radiation Hazards - The Precautions You Should Take 08/92 38 Review: Kenwood's TS-450S HF transceiver 09/92 86 Build A Relative Field Strength Meter 10/92 78 How To Make Transmitter Measurements 11/92 66 A PLL Demodulator For Amateur Receivers Circuit Notebook 01/92 22 Signalling For Model Trains 01/92 23 Automatic Night Light Timing Circuit 02/92 13 Alarm Dialler Uses An EPROM 02/92 13 8-Channel ADC For PCs 03/92 12 Courtesy Light Delay For Cars 03/92 13 Traffic Lights For Model Train Layouts 03/92 13 Adjustable 20V Power Supply 03/92 .14 Using Your Games Port For Data Input 04/92 12 Scanning Facility For A CB Radio 04/92 13 EPROM-Based Stepper Motor Driver 05/92 22 Low Cost Audio Oscillator 05/92 22 Bulletin Board Watchdog 05/92 23 Airconditioning Override With Kickdown Switch 05/92 23 Nicad Fast Charger Timer 06/92 66 Loudspeaker Protector Has Power-On Delay 06/92 66 Courtesy & Headlight Delays For Cars 06/92 67 Chocolate Wheel With Fixable Numbers 07/92 58 Sequential Combination Lock 07/92 58 Modification To Headlight Controller 07/92 59 BCD & Decimal To ?-Segment Decoding With An EPROM 08/92 1.4 Musical Chime Generator 08/92 14 12VDC To 240VAC Inverter For Small Appliances 08/92 15 High Performance Drill Speed Controller 08/92 15 Simple Lap Timer For Slot Cars 09/92 8 Traffic Lights For Model Train Layouts 09/92 8 Automatic Electric Blanket Controller Projects to Build 01 /92 16 Build A 4-Channel Guiter Mixer 01/92 28 Automatic Controller For Car Headlights 01 /92 53 Baby Room Monitor & FM Transmitter 01/92 64 0-45V 8A Power Supply, Pt.1 02/92 24 Compact Digital Voice Recorder 02/92 34 Build A Stereo Power Amplifier 02/92 42 12VDC/240VAC 40-Watt Inverter 02/92 76 Adjustable 0-45V 8A Power Supply, Pt.2 03/92 16 TV Transmitter For VHF VCRs 03/92 22 Studio Twin Fifty Stereo Amplifier, Pt.1 03/92 42 Thermostatic Switch For Car Radiator Fans 03/92 62 Build A Telephone Call Timer 04/92 18 Studio Twin Fifty Stereo Amplifier, Pt.2 04/92 30 Build The Executive Thingie 04/92 64 lnfrared Remote Controller For Model Railroads, Pt.1 04/92 76 Differential Input Buffer For Oscilloscopes 05/92 30 A Low-Cost Electronic Doorbell 05/92 36 The Battery Eliminator (3-9V DC) 05/92 58 Build A Telephone Intercom 05/92 76 lnfrared Remote Controller For Model Railroads, Pt.2 09/92 09/92 10/92 10/92 10/92 11 /92 11 /92 11 /92 11 /92 12/92 12/92 12/92 9 Tester For 2-lnput Logic Gates 9 Cross-Coupled FET Mixer 8 Automatic Soldering Iron Timer 8 Stutter Trigger For An Audio Strobe 9 Self-Contained Autofire Module For Electronic Games 8 Reversing Light Chaser For 12V Lamps 8 A Low Cost Crystal Checker 9 2-Chip Electronic Blackjack Game 9 Timer Safeguards Rechargeable Cells 34 Board Game Countdown Timer 34 Power On/Low Battery Indicator 35 High Current 0-20VDC Power Supply Remote Control 01 /92 78 Motors For Electric Flight Models. Pt.2 03/92 78 Voltage Losses In Speed Controllers 04/92 53 Switching Frequencies In Speed Controllers 08/92 58 Internal Combustion Engines For R/C Models, Pt.1 09/92 93 Internal Combustion Motors For R/C Models, Pt.2 10/92 88 Internal Combustion Motors For R/C Models, Pt.3 11 /92 84 A Low-Cost Speed Controller Using Discrete !Cs, Pt, 1 06/92 16 A Multi-Station Headset Intercom, Pt.1 06/92 24 lnfrared Remote Controller For Model Railroads, Pt.3 06/92 68 Video Switcher For Camcorders & VCRs 06/92 82 Build A 15-Watt 12VDC To 240VAC Inverter 07/92 22 Build A Nicad Battery Discharger 07/92 30 8-Station Automatic Sprinkler Timer 07/92 54 Portable 12V SLA Battery Charger 07/92 64 Off-Hook Timer For Telephones 07/92 76 Multi-Station Headset Intercom, Pt.2 08/92 22 Build An Automatic SLA Battery Charger 08/92 36 Miniature 1 .5V to 9V DC Converter 08/92 62 Dummy Load Box For Large Audio Amplifiers 08/92 68 The lnterphone Digital Telephone Exchange, Pt.1 09/92 6 Track Tester For Model Railroads 09/92 28 Heavy-Duty 5A Drill Speed Controller 09/92 46 The lnterphone Digital Telephone Exchange, Pt.2 09/92 56 A Multi-Sector Home Burglar Alarm, Pt.1 09/92 78 A General-Purpose 3½-Digit Panel Meter 10/92 16 A 2kW 24VDC to 240VAC Sinewave Inverter, Pt.1 10/92 22 A Multi-Sector Home Burglar Alarm, Pt.2 10/92 48 Build A Mini Amplifier For Personal Stereos 10/92 56 The Thunderbird Battery Charger 11 /92 16 Build A Simple FM Radio Receiver 11/92 22 Modifications To The Drill Speed Controller 11/92 24 A 2kW 24VDC to 240VAC Sinewave Inverter, Pt.2 11 /92 34 The MAL-4 Microcontroller Board, Pt.1 11 /92 40 An Automatic Nicad Battery Discharger 11/92 62 An lnfrared Night Viewer 11 /92 74 Simplifying The lnterphone Telephone Exchange 12/92 12 Diesel Sound Simulator For Model Railroads 12/92 22 Easy-To-Build UHF Remote Switch 12/92 44 Build The Number Cruncher 12/92 58 The Mal-4 Microcontroller Board, Pt.2 12/92 66 A 2kW 24VDC to 240VAC Sinewave Inverter, Pt.3 12/92 40 Building & Using The Low-Cost Speed Controller, Pt.2 08/92 82 Pt.19 Electric Traction Schemes In Sydney 09/92 89 Pt.20 Sydney's Tramways & The Ultimo Power Station 11 /92 79 Pt.21 How Electric Lighting Came To Sydney's Streets Vintage Radio 01/92 58 Restoring An AWA Radiolette Receiver 02/92 18 Console Receivers From The 1930s 03/92 72 A Look At Valve Substitutions 04/92 84 The Basics Of Receiver Alignment, Pt.1 05/92 68 The Basics Of Receiver Alignment Pt.2 06/92 6 The Basics Of Receiver Alignment Pt.3 07/92 7 Unusual Problems Lead To Interesting Repairs 08/92 6 Troubleshooting Vintage Radio Receivers 09/92 40 Repairing An Old Heathkit RF Generator 10/92 37 Vintage Radio Repairs Made Easy 11 /92 58 Converting A Battery Set To Mains Operation 12/92 74 Preventing Trouble & Making Odd Repairs Electrical Energy 01 /92 8 Pt.17 Giant Hydroelectricity Schemes In Brazil 02/92 34 Pt.18 How The Broadwater Was Tamed Notes & Errata 01 /92 93 Digital Altimeter For Gliders & Ultralights, Sept-Nov. 1991 02/92 92 Battery Charger For Solar Panels , November 1991 03/92 92 lnfrared Light Beam Relay, December 1991 05/92 92 TV Transmitter For UHF VCRs, March 1992 06/92 92 Thermostatic Switch For Car Radiator Fans, March 1992 07/92 93 40W 12V DC To 240VAC Inverter, February 1992 07/92 93 Telephone Intercom, May 1992 07/92 93 Video Switcher, June 1992 09/92 100 lnfrared Light Beam Relay, December 1991 09/92 100 Video Switcher, June 1992 09/92 100 Nicad Discharger, July 1992 09/92 100 Portable 12V SLA Battery Charger, July 1992 09/92 100 6/12V SLA Battery Charger, August 1992 10/92 100 40W 12V DC To 240VAC Inverter, February 1992 12/92 99 Studio Twin 50 Stereo Amplifier, April 1992 DECEM BE R 1992 101 . . . . TCENTRE Cash in your surplus gear. Advertise it here in Silicon Chip. ANTIQUE RADIO ANTIQUE RADIO restorations. Your one-stop radio repair shop. Specialising in restoring vintage radios, including chassis rewiring, re-condensing, quality new parts, valves, valve sockets, speakers, power & audio transformers. Secondhand radio dials & parts for most brands & models. About 400 radios in stock for sale, restoration & parts. Every restored wireless is covered by a 2year warranty on parts & labour. We restore damaged woodwork & cabinets & French polish (approx. 40 coats). Vintage car radios available for sale or restoration. Repairs done on tape decks. Open Sat. 10am-5pm; Sun. 12.30-5pm. 109 Cann St, Bass Hill, NSW 2197. Phone (02) 645 3173 BH or (02) 726 1613AH. FOR SALE WEATHER FAX programs for IBM XT/ ATs *** "RADFAX2" $35 is a high resolution, shortwave fax, Morse & RTTY receiving program. Suitable for CGA, EGA, VGA and Hercules cards (state which). Needs SSB HF radio & Radfax decoder. *** "SATFAX" $45 is a NOAA, r----------------- -------7 CLASSIFIED ADVERTISING RATES I I Advertising rates for this page: Classified ads: $10.00 for up to 15 words plus 40 cents for each additional word. Display ads (casual rate): $20 per column centimetre (Max. 10cm). Closing date: five weeks prior to month of sale. To run your classified ad, print it clearly in the space below or on a separate sheet of paper & send it with your cheque or credit card details to: Silicon Chip Classifieds, PO Box 139, Collaroy Beach, NSW 2097. Or fax the details to (02) 979 6503. Enclosed is my cheque/money order for $_ _ _ _ or please debit my 0 Bankcard 0 Visa Card O Master Card Card No. Signature_ _ _ _ _ _ _ _ _ _ _ Card expiry date_ _~/_ __ Name _ _ _ _ _ _ __ _ _ _ _ _ _ _ _ _ _ _ _ _ __ Street _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __ Suburb/town _ _ _ __ _ _ _ _ _ _ Postcode_ _ _ _ __ l I I I I SILICON CHIP SPRINKLER CONTROLLER KIT: get ready for summer with this very popular kit. Very reliable and versatile design can control eight stations and has 32 programmable START and RUN times (refer SILICON CHIP, July 1992). All settings stored in EEPROM. Can be expanded to 64 with the addition of extra memory chip and switch. Requires 24V AC to run. Complete kit including LCD & case $135 (incl. p&p}. Relays extra at $3.75 each (controller requires 9 for full kit). FROSl SWITCH KIT also available. Remote temperature probe starts the above controller in a fully programmable sequence, when temperature falls to a user selectable value (controller requires modified S/W). $60 incl. reprogramming and p&p. Available from Graham Blowes, 38 Garnet St, Niddrie, 3042. Phone (03) 337 1917 AH or (03) 575 3349 BH. Fax (03) 575 3369. SECURITY ALARM COMPONENTS: commercial quality alarm panels, de. teeters, cable, everything for complete alarm system. DIY kits. Discounted prices. 4-core alarm cable $35 per 100m. 2-core alarm cable (figure-8) $15 per 100m. PIR detectors pulse count $59 ea. Horn speakers $12.50 ea. Mail order service. Send SAE for free price list to Security Distributors, 141 Todds Rd, L.awnton, Old 4501. Phone (07) 882 0002. x I I I I I I I I I I L---------- ______________ J 102 Meteor & GMS weather satellite picture receiving program. Needs EGA or VGA plus "WEATHER FAX" PC card. *** "MAXISAT" $75 is similar to SATFAX but needs 2Mb expanded memory (EMS 3.6 or 4.0) and 1024 x 768 SVGA card. All programs are on 5.25-inch or 3.5-inch disks (state which) & include documentation. Add $3 postage. Only from M. Delahunty, 42 Villiers St, New Farm, Old 4005. Phone (07) 358 2785. THE HOMEBUILT DYNAMO: (plans) brushless, 1000 watt at 740 revs. $A85 postpaid airmail from Al Forbes, PO Box 3919 - SC, Auckland, New Zealand. Phone Auckland (09) 818 8967 anytime. 8051 MICROCOMPUTER PROTOTYPING PCB $30 - similar to my ROMLoader EA Jan 92. Provision for 8255 PPI, 9346 EEPROM, 2K-32K SRAM, 2K-32K EPROM, MAX232, DIP switches & expansion header. Send A4 SAE for article. Tantau, PO Box 206, Gordon 2072. NEW NOTEPAD Computer by Amstrad as advertised on TV. Z80B micro, Builtin Standard Parallel, Serial, Basic, Word Processor, Dictionary, Calendar, Diary, Address/Telephone book, World time clock/alarms, Calculator, PC File transfer. $390 inc post & ins. For more info send a 45c stamp to Don McKenzie, 29 Ellesmere Crescent, Tullamarine 3043. Phone (03) 338 6286. STEPDOWN POWER transformer. Atco 1kVA, 240VAC in, 11 0VAC output. $250. Phone (060) 31 3577 (Bus); (06) 24 1168 (AH). NICAD BATTERIES: D-size 4Ah. At less than half price it's the best deal in town. $4.90 each plus p&p. Phone (052) 78 8298. PAY ASIAN PRICES for common electronic components. No minimum. Ask about hard to get items. Local SAE for details. DIY Electronics, GPO Box 904, Hong Kong. FOR SALE: we have a number of Plessey 2001 B-MAC satellite receivers for sale. This model is currently retailing at over $2200.00. These are in good going condition and complete with remote controls and handbooks. If interested, please make a cash or Bankcard offer to: Langridge Electronics, PO Box 290, Norfolk Island 2899, or fax to (0011) 6723 22833. COMPONENT PACKS, 30 trimpots, Bourns, Beckman etc, mixed values and types including multiturn. 400 metal film ¼W resistors, most are 1% or 2% Beyschlag, mixed values including some E96 and E192 series. 200 carbon film ½W and 1W resistors, most are Beyschlag 1% or 2%. All component packs $12 ea plus $5 p&p. Japanese transistor pack with two each of 2SA 1069, 2SC923, 2SC 1826, 2SC3157, 2SD381, 2SD667, $15 per pack. Electronic component pack, 400 items including ICs, transistors, diodes, resistors, trimpots, capacitors, relays, fuses etc. All new components, $25 per MEMORY EXPANSION PRICES AT OCTOBER 19TH, 1992 SIMM 1Mb xll 1Mbx3 1Mbx8 4Mbx9 4Mbx 8 DRAM DIP 1 x 1Mb 256x4 41256 1Mbx4 ?Ons ?Ons 100ns ?Ons 80ns $46 $42 $37 $160 $150 ?Ons ?Ons 80ns (stat) DRIVES SEAG 89Mb SEAG 107Mb SEAG 130Mb SEAG 245Mb 14M 15M 12M 12M $5 $5 $2 $23 $320 $350 $430 $780 IBM PS.2 50155/70 70135 90195 2Mb 4Mb 4Mb $115 $180 $190 TOSHIBA T2000SXe T3200SX T44l6400 T5200 4Mb 2Mb 4Mb 2Mb $260 $135 $345 $135 MAC 2Mb SI & LC 4Mb P'Book $83 $260 BOARDS & PTRS 8MbAT W2MB $232 8Mb PS2 W2MB $234 4Mb HP Laser W2MB $155 1MbTI W1MB $80 Sales tax 20%. Overnight delivery. Credit cards welcome. Ring for Latest Prices Plans Kits and PCBs 100W Valve Amp PCB ............................................... $30 Valve Amp PSU PCB ................................................. $25 Universal PSU (±5/±12V) Dual Supply ...................... $10 Digi 125 100W amp/pair ............................................ $1 0 ETI 1623 PIA for PCs ...................... ....................... $40 Max 1/0 Board ............................................................ $40 Max Kit ..................................................................... $169 LM380 3.5 amp PCB ................................................... $7 AEM 35W amp kit ...................................................... $20 ETI Audio Toolkit PCB ............................................... $10 AGC Amp PCB ............................................................ $7 Z-80 Miniprocessor PCB ............................................ $50 6502 Miniprocessor PCB ........................................... $50 6809 Miniprocessor PCB ........................................... $50 8048/8049 Developers board complete B& T ........... $199 IBM PC Prototype PCB .............................................. $50 EPROM Programmer .............................................. $299 ESL-1 Electrostatic speaker kit/pair inc manual ..... : $899 ESL-1 Assembly Manual ........................................... $50 P.C. Computers (08) 332 6513 36 Regent St, Kensington SA. 1st Floor, 100 Yarrara Rd, PO Box 382, Pennant Hills, 2120. Tel: (02) 980 6988 Fax: (02) 980 6991 PELHAM FIX-A-KIT KIT REPAIR & CONSTRUCTION TRANSFORMER REWINDS 3 MONTHS WARRANTY ON REPAIRS 12 MONTHS WARRANTY ON CONSTRUCTION TECHNICAL ASSISTANCE ALL TYPES OF TRANSFORMER REWINDS HVCAL ELECTRONICS TRANSFORMER REWINDS Design, Manufacture & Repair of Electronic Equipment Reply Paid No.2, PO Box 438, Singleton, NSW 2330. Ph: (065) 76 1291. Fax: (065) 76 1003. (02) 633 5477 pack, plus $8 p&p. Valves, CV3998, 12AX7, 12AY7, 12BY7A, 3A4, 6AM5, 6J7G, all $8 each or 10 for $70 (can be mixed). Open Thursday, Friday 4pm8pm, Saturday 9am-4pm, 143 Grays Rd, Enoggera, Qld. Ph (07) 355 1314 or (07) 855 1880 AH. Fax (07) 855 1014. Visa, Bankcard, Mastercard available for fax or phone orders over $20. Secontronics, PO Box 2215, Brookside, Qld 4053. NEW 280 SINGLE BOARD COMPUTER: designed for the 1990s. Also modern kits. Local SAE for details. DIY Electronics, GPO Box 904, Hong Kong. CAPACITORS, quality Siemens 10000µF/1 00V cans made in Germany, $20 ea or $15 ea 10 up. Phone (02) 411 1539AH. INTELSAT· International Satellite (Television) Receiving System (movies, sport, news). Commercial 4.8-metre solid dish plus system electronics package. Can see operating. $3995.00 ono. Phone Rod (08) 387 0372. MULTIPLEXERS - CASE 825 (x4) 24 channel V.24, CASE 815 (x2) 12 channel V.24, optical link 48kbps. No reasonable offer refused. Phone (02) 411 1539AH. ON SALE NOW: First Edition Vintage Radio Calendar, in full colour. Featuring a selection of Australia's most photogenic radios. Ideal Christmas gift for friends and collectors overseas. Available from Resurrection Radio, 51 Chapel Street, Windsor, Victoria, Australia 3181. Phone (03) 529 5639. $18.95 plus $2 postage. SOLAR POWERED MOTOR KIT: a 6V 50mA solar panel with terminating clips, a very efficient motor to suit, and instructions, great for education and experimenting. Only $7 per set or 5 sets for $28. Ref XXJAN93101. * ELECTRONIC KEY: use it to activate door strikers for entering buildings, for switching car alarms, central locking, the most secure key ever (see EA, July 1992). On special<at> $49.90 for two keys and one decoder kit. Ref XXJAN93103 . * ULTRASONIC CAR BURGLAR ALARM (SC, May 1988): based on a crystal locked ultrasonic movement detector. Can be used as a detector or a self standing alarm, has provision for DECEMBER 1992 103 LOCAL TRADES & SERVICES * JV Tuners - Repairs Tuner • • • • repairs for TVs & VCRs Shorted Turns Tester High Voltage Probe Degaussing Wand Remote Control Tester * Transfonner Rewinds For all types of transformer rewinds. (02) 7741154 Fax (02) 7741154 (065) 761291 Fax (065) 761003 Ian .J Truscott's Electronic World EEM Electronics \fail or credit card facilities Printed circuit hoard assembly, switch mode power supplies repaired. Design work from start to finish. Ring anytime 9am-91>m Mon-Sun . (03) 7233344 Fax (03) 4192808 (03) 4011393 For sen ice & repair work T. A. Mowles Silicon Chip Printed circuit hoards for the hobbyist. For ser,ice & enquiries contact: To ad,ertise your products or sen ices, please call Sharon on (08)3265590 (02)9795644(018)285532 bonnet/boot protection, flashing light and back-up battery operation. Clearance at below half price at only $24.90. Includes the PCB, all parts except the screw terminals, a pair. of ultrasonic transducers. Ref XXJAN93102. * SOLAR LIGHTING BARGAIN (EA, Nov 1992): this kit has three separate sections that are contained on one PCB, but can be separated: (1) a crystal .locked ultrasonic movement detector; (2) a fluorescent tube inverter (4-20W) with logic circuitry; (3) a solar battery charging regulator and an incandescent lamp switcher-pulser, which employs a Mosfet switch. As a package special we are offering the complete kit for the three sections plus six 6V/1W solar panels for a total cost of ONLY $99! RefXXJAN93104. * SWITCHES: high quality miniature enclosed Italian (FEME) 1, 2, 3 and 5-pole, 12-position switches, $2.80 ea or 10 for $20. Ref XXJAN93105. * SINGLE CHIP MICROCOMPUTER: in the form of a telephone display, based on a NEC uPD7503G single chip micro IC and an LCD display to suit. See our previous advertisements for more information. Clearance $9 ea or 5 for $30 ! Ref XXJAN93107. * MYSTERY LASER: includes a 12V universal power supply kit, plus a very small, modern, brand new 0.5mW laser tube to suit. To top the bargain we will include a diverging lens (holography, etc) with the deal for a TOTAL PRICE OF $79!! Ref XXJAN93106. Major cards accepted with phone and fax orders. Total cost of certified p&p: Australia $5, NZ (airmail) $10. Oatley Electronics, PO Box 89, Oatley, NSW 2223. Phone (02) 579 4985. Fax (02) 570 7910. 104 SILICON CI-I!P Advertising Index All Electronic Components ........ 63 Altronics ............................... 90-92 Antique Radio Restorations .... 102 A-One Electronics ................ 36-39 Av-Comm ..... .. ............................. 6 Breakthrough Computers .......... 41 Central Coast Amateur Radio ... 96 David Reid Electronics ................ 5 Dick Smith Electronics ......... 18-21 EEM Electronics ...................... 104 Electronic World ................. 94, 104 Emona Instruments ................... 89 Ford Motor Company ............. OBC Geoff Wood Electronics ............ 33 Harbuch Electronics ...........;...... 97 Hycal Instruments ................... 103 Jaycar Electronics ......... 49-56,IBC JV Tuners ................................ 104 Kalex ......................................... 77 Nilsen Electronics ....................... 7 Oatley Electronics .............. 87,103 PC Computers ........................ 103 Pelham ............................... 73,103 Peter C. Lacey Services ........... 84 Philips Test & Measurement... ... 31 Plough Book Sales .................... 77 Procon Technology .................... 97 ACS Radio .............. ................ 104 Reserve Electronics .................. 93 Resurrection Radio ................... 97 Rod Irving Electronics .......... 78-83 Scan Audio ............................. 9,62 Scientific Devices ...................... 95 T. A. Mowles ..................... :... ... 104 Technical Applications ................ 11 Transformer Rewinds .............. 104 Westinghouse ........................ ... 15 RC§ RADIO PTY LTD ~~'.'i~1, ~ U16if~I Ill RCS Radio Pty Ltd is the only company that manufactures and sells every PC board and front panel published in SILICON CHIP, ETI and EA. PC Boards Printed circuit boards for SILICON CHIP projects are made by: • Jemal Products, 5 Forge St, Welshpool, WA 6106. Phone (09) 350 5555. • Marday Services, PO Box 19-189, Avondale, Auckland, NZ. Phone 88 5730. RCS Radio Pty Ltd, 651 Forest Rd, Bexley 2207. Phone (02) 587 3491 • RCS Radio Pty Ltd, 651 Forest Rd, Bexley, NSW 2207. Phone (02) 587 3491. :;:=J I 0 NEW FROM JAYCAR HOT-SOL GAS SOLDERING IRONS. Jaycar Electronics proudly announce a new force in gas soldering irons. The Hot-Sol needs no cords or gas bottles. Al I you need is standard Butane cigarette lighter gas which is available everywhere. The Hot-Sol has adjustable temperature control, you can vary it from the equivalent of 10 to 60 watts. Features include: • Built in gas igniter. • Totally see through case - see how much gas you have left at a glance. • Supplied with protective cap with Pocket Clip. • Fully portable, always ready to use. • Heavy duty, tip temperature up to 400°C. • Hard working, one fill will last over an ho • Refills in seconds. • Low cost. ::< • No leakage current to sensitive circuits. ~~A v. • Spare tips available, and they are not expensive. • Hot blow tip available. Supplied with 2.4mm tip. • 1 year warranty on unit. Hot-Sol Gas Soldering Iron_ONLY $ HOT-SOL SERVICE KIT This kit includes the same soldering iron, but comes with a range of accessories, and its all housed in its own case. Includes: • Hot-Sol Butane Gas Tool. • Protective cap and pocket clip. • Non slip stand with sponge. • Torch Tip which gives a flame. • 2.4mm Soldering Tip. • Hot blow tip for shrinking heatshrink tubing. • Scoop for feeding tubing to hot blow tip. • Hot knife tip. • Roll solder. • Case which holds everything. MAIL ORDER VIA g Optional Extras: • 1mm Soldering tip with catalyst. Cat. TS1704. $9.95. • 2.4mm Soldering tip with catalyst Cat. TS1705. $9.95. • Hot air tip fo r heatshrink. Cat. TS1708 $9.95. • Small stand to suit soldering iron. Cat. TS1720 $3.95. Flame Torch Tip Cat TS1710 $3.95. $64 95 ~rJ4trim ■ 1 0 ~-~ &I ;J;· FREE CALL FOR ORDERS ONLY ~oA t o~~:5E~~ncord 2137 : ~! ~s l ~~?sERhodes 2138. ~, $50 $99.99 $6.50 ROAD FREIGHT ANYWHERE IN Telephone (02) 743 5222. --·-·- 1 (DOB) 022 888 '----OV_ER_$_10_0 _ $_8._00----' AUSTRALIA (up to 20kg) $13.50 Fax (02) 743 2066. , HOTLINE (02) 743 6144. ADELAIDE SA 190 Wright St (Cnr Selby St) (08) 231 7355. Mon-Fri 9-5.30 Fri 8.30-Sat 9-1 2. BURANDA QLD 144 Logan Rd (07) 393 0777 -,\ . I Mon-Fri 9-5.30 Thurs 8.30 -Sat 9-4. COBURG VIC 266 Sydney Rd (03) 384 1811. Mon-Fri 9-5.30. Fri 8.30-Sat 9-4. MELBOURNE CITY Shop 2, 45 A'Beckett St Ci ty (03) 663 2030. Mon- Fri 9-5.30 Fri 8.30-Sat 9-2. SPRINGVALE VIC 88 7-889 Springvale Rd Mulgrave (03) 547 1022. Nr Cnr. Dandenong Rd. Mon-Fri 9-5.30 Fri 8.30 - Sat 9-2. SYDNEY CITY 129 Yo rk St. (02) 267 1614. Mon-Fri 8.30-5.30 Thurs 8.30pm - Sat 9-4. BANKSTOWN 363 Hume Hwy Cnr Mered ith St (02) 709 2822. Mon -Fri 9-5.30 Th urs 8 30pm - Sat 9- 4 - Sun 10-4pm GORE HILL 188 Paci fic Hwy (Cnr Bellevue Ave) (02) 439 4799. Mon-Fri 9-5.30 Thurs 8.30 - Sat 9-4pm. PARRAMATTA 355 Ch urch St (Cnr. Victoria Rd) (02) 683 3377 Mon -Fri 9-5.30 Thurs 8.30pm - Sat 9-4pm. Sunday 10am-4p m. PENRITH 199 High SL (047) 21 8337 Mon-Fri 9-5.30 Thu rs 8.30 - Sat 9-4pm Sun 10-4pm. RHODES 6 Leeds St. (02) 743 5222 . Mon -Fri 9-5.30. __, ■ VISA i!U ______ _____________________________ ~~-