Fullscreen HTML5Med Res (??MB)HTML4

A LOOK AT LARGE SCREEN MONITORS AUSTRALIA'S DYNAMIC - ELECTRONICS MAGAZINE~ - - -~ - D I PTRONICS- '\1'at\ - · \ ~ • • .V :-; ~~,v.... --+-------------1---"'1~ =~~,!f~!~E,, 0 f\ Bayswa er., 1.5. P.O. Box 664, Bayswater 3.153 Telephone: (03) 761 4466 \ Facsimile: (03) 761 4161 Toll Free: (008) 800 482 ~ ~ ~ m~ Road, 1::11~ namsgate Sans Souci 2219 Telephone: (02) 529 Facsimile: (02) 529 ,"" . ----------.-------\ a,,, \ 227,7 589\ • Capac.itors • Connectors • Fans • Filters • Headers • LEDs • Plugs • Rectifiers • Relays Resistors • SCRs • Triacs • Sockets • Swtiches • Terminal Blocks • Varistors ~ _ _"'J ...J - _/ r.:; ::;/:__ .:J J 7);...J ...J LI ...J // ...J '..,I -..,;;,.J ,...J _.,,. ...J ...11..=...J 'W...J_.,,....J~ "-'-J ...J _.,,. ...J ...J !f , U ,_ -~_,../_.__:, ;_.__ __ ~ , -, - ...J __J - ...J I ...J .! l ' I --Vol.5, No.5. May 1992 •• _, • I FEATURES , ,,. , (" .. o.' • • • 6 We Take A Look At CD ROM by Darren Yates FORGET ABOUT CAD & desktop publishing on a small screen. A high-resolution, large-screen monitor is really the way to go. We tell you what to look for in our story starting on page 16. A large range of software is now available 16 Computing On The Big Screen by Jim Sharples A look at large-screen, high-resolution monitors _ _ _ PROJECTS TO BUILD __ _ __ 30 A Low-Cost Electronic Doorbell by Darren Yates Build it from junkbox parts 36 The Eliminator by Marque Crozman It runs your personal player from a 12V DC supply 58 Build A Telephone Intercom by Greig Sheridan Works jusdike a real telephone system 76 lnfrared Remote Control For Model Railroads, Pt.2 by John Clarke Remote control receiver circuit & pulse power board construction - SPECIAL COLUMNS • f • • • • ... DO YOU HAVE A COUPLE of old telephones sitting in your junkbox.? This project will turn them into a useful intercom unit that works just like a real telephone - see page 58. • 24 Computer Bits by Paul Lynch The PC game is changing again - OS/2 is really here 40 Serviceman's Log by the TV Serviceman Five faults all at once! THE SERVICEMAN suffered a frightening encounter with a Panasonic TV set this month. His tribulations begin on page 40. 68 Vintage Radio by John Hill The basics of receiver alignment, Pt.2 86 Amateur Radio by Garry Cratt · Receiving weather satellite signals, Pt.2 ~ . - . "' DEPARTMENTS. . . 2 Publisher's Letter 4 Mailbag 22 Circuit Notebook 53 Product Showcase 88 Back Issues .. Ask Silicon Chip Notes & Errata Order Form Market Centre 96 Advertising Index 90 92 93 94 . . ... DON'T BUY A new doorbell to replace your bro,ken-down unit. This design comes in a special case & uses readily available parts to produce a realistic & pleasant "ding-dong" sound. Construction begins on page 30. MAY 1992 1 Publisher & Editor-in-Chief Leo Simpson, B.Bus. Editor Greg Swain, B.Sc.(Hons.) PUBLISHER'S LETTER Technical Staff John Clarke, B.E.(Elec.) Robert Flynn Darren Yates Reader Services Ann Jenkinson Sharon Macdonald Sales & Marketing Mgr. Sharon Lightner Phone (02) 979 5644 Mobile phone (018) 28 5532 Regular Contributors Brendan Akhurst Jennifer Bonnitcha, B.A. Garry Crall, 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 Ply 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 p21tents. 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 2 SILICON CHIP PC technology is moving rapidly ahead This month, we are taking a look at three areas of PC technology that are evolving rapidly. The first of these is our feature article on large screen video monitors. These are not new of course and specialised labs employing CAD programs have had them for quite a few years. What is new is that they are now becoming much more affordable although most private users would still baulk at paying between $3000 and $5000 for a high resolution colour monitor and accompanying video card. Still, the prices were very much higher as little as two years ago and as computer prices have dropped so much, you can now buy a high end system with a big monitor for the same price that you would have paid a few years ago for a less capable system with a 14-inch screen. We also take a look at one of the latest CD ROM packages. When CD ROM came out a few years ago it was stymied by a severe lack of software and the hardware wasn't cheap either. That has changed rapidly and there is now a wealth of interesting software on CD ROM. We can see many families adding a CD ROM to their home computer and thereby gaining a very good reference base for school assignments. And finally, we take a look at OS/2 version 2. IBM's much vaunted 32-bit replacement for DOS has languished badly since it was originally released in 1987 but now it looks set to really compete with Windows-based software, with the advantage that it should operate much faster. It will be very interesting to see how much OS/2 based software appears over the next few years - the PC will evidently continue to change extremely rapidly over the coming years. These rapid changes do present their problems though. For people considering buying a home computer so their children will not be left behind, there is a particular dilemma. Whatever computer they buy now, it is not likely to bear much similarity to the ones that will be used when their children enter the workforce in five or more years time. And for business users, the problem is that no matter what system they buy, its value will rapidly diminish in the space of two years or so. So if they are making buying decisions now, the computers must pay for themselves several times over in two years or less. The other side of the coin is that if businesses do not continually update their equipment, and that includes their computers, then they will be rapidly left behind in the marketplace. Leo Simpson Ars your eugfo111srg /Javi11g trou/Jls gstti11g t/Jroug/J to your p/Jo11s/rax li11s ? illl'i~I a11d you'vs loGt t/Js Gals /lseauGs your fax Gwite/J iG 11ot doi11g w/Jat you wa11t it t o do? ~~.-. ,-.,_.,..._ -,-,-~ s:~1,,,.-,-,~,,. Why the EASY-CONNECT ? The VSI EASY-CONNECT 11111 I I ll <at>ii Bec ause the EASY-CONNECT is the most flexible and complete phone-fax line sha ring device av ailable in Australia today. Integr ate an y fax with any answering machine on an y telephone system without th e limitations of faxswitch devices or 3 in 1 fa x s yst ems. The Most Advanced PHONE-FAX/LINE SHARING DEVICE NO Confusing Vo ice Messages . NO Perio d s o f Silence. NO Unusual Dial Tones. NO Delay s. NO Frust rat ed Callers. T he E A SY -CONNECT is totally trans pare nt. Yo ur callers w ill never know it's o n the line ! * Sa ve installat ion and re ntal costs for a s epara te line. ** Latest Sw itches incoming Fa x calls automatically on receipt of calling Fa x ton es. VOICE PRIORITY technology. * Installs in minute s on ANY PHONE SOCKE T usin1 supplie d connectors. * DOES NOT REQUIRE EXPENSIVE TELECOM INSTAL ATION . Other fa xswitch systems ? Clum sy fa x priority operation . Delay s, pause s. voice messages, fru s trate d ca llers . Inflex ible and limite d operation with oth er device s. Mus t be fitted on fir s t socket. Poor history of cus tomer satisf action. Dedicated fax line ? $210 min . installa tion, $ 22 monthly rental thereafter. $472 min. in first year, over $1000 in 3 years. (1991 fees) Installation delays. Ch ange of premis es results in further $ 210 installation fee . Inefficient use of resources for small businesses. No available lines in some areas. * Adds HOLD FACILITY to all phones. Puts a call on hold from any phon e. * Manual Tr a nsfer to Fax before, dur ing or after voice conversation. * Can interupt a voice conversation, to send or receive a Fax, then resume. * Works with or without an Answering Machine. Pulse / Ton e dial compati a bl e. * Will operat e with Fax, Phone, Modem and Answering Machine on one lin e . * No restriction to the numbe r of extensions or other de v ices conn ec ted t o it. 8v~..'.'R'tt1~~!~~~ : ~~o~~~CJe?i:~\~ry i~g~e~ l~~l~!r~gae2 M~r'i.kn~~ -of ciga re ttes. Also work s with Command er, Keyphone or PABX (technic al installation req u'd) The EASY-CONNECT is c ompatible with the changing ne eds. Provides Lightning protection for the Fax and other devices connect ed to it. Made in the U.S.A. Telecom Australia Permit Number: A90 / 14B / 03 4 2. Size: 8 5mm x 9 0mm x 33mm . Wgt: 225g. * * * ** * 1!1 L Run your business efficiently with the VSI EASY -CONNECT Only $399.00 2 Y E A R Exchan ge Warranty LAB4 Frequency Counter, Function Generator, D.M.M., Power Supply, 4 in 1 Unit FEATURES ■ One instrument with ■ Frequency Counter, Four Tes t and Measuring Systems. Function Generator, Digital Multimet er and Po wer Suppl y. ■ Ideal for Labor at ory, Produ c tion Line and R & D Engineer's Wor king Bench . ■ High Accu racy and Low Cost for Specia lis t s a nd Hobbists. ■ Unique Performance to Save Spac e. ■ Light Weight and Attractive Design . ■ Simple and Ea sy Operation. ■ Full Overload Protection. GENERAL ■ Po w er Requiremen ts: 115 / 240V AC 50/60H z. 120VA with Full Loaded Power Supply. Size: 375(W) x 160(H) x 3 40(0) mm. ■ Weight: 11Kg (approx.) ■ ■ #1 Frequency Counter #2 Function Generator #3 Digital Multimeter #4 Power Supply ■ ■ ■ 3 1/2 Digit LCD Display. ■ Auto/Ma nu al Range. ■ ■ ■ Output ■ Output Range: 1Hz - 100MHz ■ Sensitivity: 1Hz - 60MHz: 15mV 60MHz - 100MHz: 25mV. ■ Resolution: 0.1, 1, 10, 100Hz. ■ Gate Time: toms, 100ms. 1s, 10s. ■ Display: 8 digits LED. Sine, Square, Triangle, Skewed Sine, Pulse, TTL Level Square. ■ Frequenc y: 0.02Hz - 2MHz. ■ Output: 0.1 Vpp - 20 Vpp. ■ Linear and Log Sweep: Internal: 20ms - 2s. DC V, AC V, Ohm's, DC A, AC A . ■ Ba sic Ac curacy:+/- 0.5% ■ Data Hold f unct ion. ■ Memor y Mode for Zero Ohm adjus tm ent a nd Relative function. ■ Inpu t Imp edance: 10M oh m. ■ 5~lg~71~~~~;,~J~~ ;'cf!Joo ohm . 3 1/2 Digit LCD Display V & A. 11- O - 50V, 0 .5A max. 12- 15V, 1A (fixed). • 3 - 5 V, 2A (fixed). ■ Full Over Current Protection . ■ Ripple: • 1- 1mV max. Ripple: • 2, • 3- 2mV max . ■ Lo a d Regulation: 11- 0 .01% + 5mV ■ Output Only $837.00 incl. tax. $722.00 ex. tax. 12 months Warranty CITIZEN ET -8 Pocket Translator Ill I with Japanese and Chin e se tra nslations I ■ The ET-8 translates more than 1,500 words and 1,000 useful expressions instantly between English, French, German, Italian, Spanish, Dutch, Jap anese a nd Chinese. ■ Home Time, World Time, Cl o ck and Alarm func tions. ■ Calculator, Metric Con ve rs ion , Currency Conversion functions. ■ Instruction Manual in 8 different languages. ■ Doi Matrix LCD Display. ■ Handy Poc ke t Size, ideal for travell ing. ■ 12 months Warranty. Now available at an affordable price I ■ ■ Luminou s Intensity "' 20m A: 7mcd (min.). 14mcd (lyp.) Forwa rd Voltage: 2.7V (min.l . 3.0V (t yp.), 3.5V (ma x.) o 20mA. Reverse Voltage: 5.0V. Full Viewin g Angle: 30 deg. Wave Leng th: 470nm. ■ Ava ilabl e in 3mm and 5mm case. ■ Ca se Colour : water-clear. ■ ■ ■ 3mm Part No.: L-934BC (BLUE) 1 to 9: $3.95ea. 10+ $3.55ea. 50+ $3.20ea. 100+ $3.00ea. 5mm Part No.: L-53BC (BLUE) Only $149.00 David Reid Electronics A.C.N. 0 01-372-372 12 months warra n ty 1 to. 9: $3.95ea. 10+ $3.55ea. 50+ $3.20ea. 100+ $3.00ea. 127 York St, SYDNEY 2000 Ph: (02) 267 1385 P.O. Box Q103,SYDNEY 2000 Fax: (02) 261 8905 Pos t al Charges $5 - $25 ......... $4.00 $ 26 - $ 50 ...... $6.00 $ 51 - $ 100 ..... $7.00 $101 - $4 99 .. $9.00 $ 500 + ............ FREEi MAILBAG Radiation limits for low power transmitters An article, published in the March 1992 issue of your magazine concerning a project for a low-power UHF transmitter for use with VCRs, has come to the Department's attention. This equipment is subject to Equipment Compliance Requirement 315 (ECR 315) incorporating Ministerial Standard 315 (MS 315) for Wireless Video Equipment, copy enclosed. If in the course of an investigation of a complaint by the Department, this device is found to be the cause, then there could be some problems for the owner of such equipment. If further investigations show that the equipment does not meet the requirements of MS 315, under the Radiocommunications Act 1983, it would become a sub-standard device. Possession of a sub-standard device is an offence under the Act. In order to assure compliance with MS 315, it would be necessary to submit a device with an appropriate antenna to the Department for compliance testing. The fee for testing this device is $420 plus $50 for a certificate. It would also be a requirement for parts to be labelled correctly stating that the device complies with MS 315 and quoting the Departmental approval number. Although the exact power output is not stated, the MS 315 requirement is that the peak vision carrier field strength shall not exceed 76dB microvolts per metre at three metres. I commend your magazine for warning users of the potential to cause interference to neighbours. However, from the above it is evident that the problem could become more serious. Jim Little, Radiocommunications Operations Branch, Canberra, ACT. Appreciation for the TV Serviceman Do excuse my addressing this note to just "The TV Serviceman" but that was the writer of your "Serviceman's Log" column as listed in the index. I 4 SILICON CHIP am rtot in the habit of writing fan letters but I felt moved today, just as I started to read my newly purchased copy of SILICON CHIP, to drop a few lines to express my appreciation of your column. Indeed, I find that it is the first part of the magazine I turn to! Just can't wait to get my feet up with a cold drink at hand and read of your latest antics and trials and tribulations. I am an electronics engineer by profession, though it would be more accurate to say hard-core tinker in all honesty. I have worked in a semiconductor factory, then serviced computers, and lately am moving into software. In all that time, and ever since I was old enough to hold a screwdriver come to think of it, I have had on many occasions cursed gremlins, damned elves and chased ghosts, convinced that science and technology had nothing to do with any of their handiwork. ICs that test fine but just do not work in circuit, computers that work perfectly the moment I so much as look at them (but not at other times) , programs that adamantly believe 2 + 2 = 5, and even coils that sing an elegant soprano ... I have had my share. Reading in your articles of similar plagues Down Under may have been what has kept me sane (though I suspect there are folk around here, especially my long suffering wife, who will claim otherwise). At the very least, it has been therapeutic to know I have not been singled out for the undivided attention of you-knowwhat. On a more serious note, I have benefited from the nuggets of wisdom passed on, and have saved time, effort and money due to hints and shortcuts in your column. And the cartoons really do illustrate your points quite admirably. My compliments to the artist! A big thank you for the entertainment, consolation and information. I look forward to reading your column for a long, long time to come. Y. W. Loke, Petaling Jaya, Malaysia. SILICON CHIP, PO Box 139, Collaroy Beach 2097. Support for microprocessor kit Regarding the suggestion that you develop a microprocessor development kit, I believe that you might be surprised at the amount of interest. It seems that there is a fair scattering of people who want to get closer to the technology than the use of a PC usually allows. Some satisfy this urge by getting something like a Commodore 64, which is fairly powerful and yet simple enough for "hands on" experience and modification. On the other hand, if one wants to start from ·the ground up, there is almost nothing better than a kit for getting acquainted with the nitty-gritty. Provided the price can be kept reasonable, it would be attractive to keen students, and find use as a programmable controller for a wide range of devices. There would be problems in choosing the chip-set for such a kit. Obviously, one type ofMPU would have to be chosen and any choice would be objectionable to some potential users because of price and availability (of support chips, too) and because the order-code is not "as good" as one's preference. Then too there are onerous decisions to take, like the notion of an RS232 (serial) interface, which would (according to some) eat up valuable board space better utilised for parallel input/output access. It is perfectly feasible to build a small system from scratch using perf board and point-to point wiring. In fact, this is the way I built a microcontroller for a wheelchair as a TAD (Technical Aid to Disabled) project. It used a 6800 MPU, 6810 RAM (128 x 8), 2716 EPR0M (2Kx 8), 6821 PIA and a modicum of other components for "logic glue" and analog signal handling. Such an effort is somewhat harder than just soldering bits into a readymade circuit board but the sense of achievement is very rewarding. E. Wormald, Florey, ACT. Function generator Frequency Counter Digital Multimeter Power Supply Ideal for the professional and keen hobbyist. Saves bench space. High accuracy yet low cost. Just check the features - Function Generator • Sine, square. triangle. skewed sine. pulse TTL level square • Covers 6.02Hz to 2MHz • Output from 0.11/pp to 20Vpp • Linear and Log sweep - 20ms to 2s (int) or 100:1 VCF (ext) • 500/600'1 output Miniscope The pencil iron wrth real power. Manual control of temperature while • soldering. Surts light to medium dutv work e 10W to 70W ad1ustable • Ad1ustable 200° to 500°C • 5 seconds to reach 20'C • Easy owner maintenance • Low 4V supply • Automatic SWIICh·off Frequency Counter e 1Hzto100MHz e 15mV sensitivity to 60MHz • 0.1 to 1OOHz resolution • 10ms to 1Os gate • 10MHz reference with 5ppm stability . • 8 digrt display wrth annunciators Dialtal Multimeter e 31/2 digrtLCD • Auto/Manual ranging • Vdc, Vac.n. Ade, f>i.c functions • 0.5% basic accuracy e oata Hold • Memory mode for relatiuve measurements and zeroing n's 1111!21 H!1hli1ht .,,..., c)ioice ~iH ti.. • • - ~ •"" preu !Dirt r i.. t letter (If ygur cMice. The [£SC ) l<e<,4 ,..~ M •se<l lo e,il Power Supply • 3 1/2 dig rt voltage display • Triple OUtQUt e Oto 50V. 0.5A e 15V 1A and 5V 2A fixed e 1mV ripple • Full overload protec1ion at $837 .DOinc tax $722.00 ex tax Cher/r fhe11 rilu, flllurBl- • 3999 count high r11afutian • El1v1n 11/nclian, - Vdc, Vac, Ade, Aac, ohm,, diode, logic, cantinuity1 fr1qu1ne1, upac,tanee 1nd tnn111tor hf• e PH/r hold button • Autom1tic paw,r off • 0.5% b11ie 1ccurac1 • Shack proof from 1.5m drop • Writes captured data directly to disk to allow maximum capfure butter • CRC checksum calculations • Auto-configuration to any of the comms ports 1 to 4 . • Time-stamping (absolute and relative) including delta time calculations • Split line DTE over DCE displU 80 Send $10 for a demo disk. refundable on purchase. Handy Probe Multimete Ideal for tight spots !ci' tf~mv. 4V. 40V. 400V. 1000V Vac 400mV. 4V, 40V, 400V 750V No need to turn your head to read this multimeter. The readout is right there in the probe! Auto and manual Ade 400uA, 4mA, 40mA. 46OmA, ranging, 3.5 digrt large 14mm LCD 2A, 20A display • all in a handy probe. Logic Aac 400uA. 4mA. 40mA. 400mA. testing function for CMOS/TTL. Data 2A. 20A Hold fiutton, Diode test, Continuity Ohms 400n. 4kn. 40kn. 400kn. 4Mn,40Mn ~~~!~ie~iig1~MV?ws all functions. Frequency 0-4MHz autoranging, • DC Voltage from 200mV to 500V 40MHz (500mV min) Capacrtance 4nF. 40nF. 400nF. 4µF. • AC Voltage from 2V to 500V 40µF • Resistance from 200n to 20Mn Transistor hfe 0-1000 pnp/npn • AC/DC Current to 200mA Continuitv 2kHz buzzer, <50n • Continuity check to 2kn Logic to 20MHz • Logic Testing to 1MHz and 1µs Power Off after 15min $55.00 $166.80, $139.00 ex tax • Diode Test 2V Heatshrink Tube • PHS series to UL/DIN standards • 40/cV/mm breakdown • • • . 600Vratlng 9D'C shrink temperature Supplied in metre lengths 1.5mm to 25mm diameters Call tor pricing ET&OL &OW 24V Soldering System e Infinitely adjustable 200°C to 470°C e Illuminated temperature readout monitors actual tip temperature • Select tip temperature required • Zero voltage swrtchning for maximum component safety • 60W of back-up power - 30W _pencil option • Burn-proofflexible lead Weller Soldering Stations WTCPS !83fH~· itL-1 SCOPE·MINISCOPE SCOPIE·PH20·5PK SCOPE·PSU SCOPE-STAND SCOPE·SUPERSCOPE 60W Adjustable w/· Oisp MINISCOPE Handpiece (needs PSU) 5 Piece Hobby Pack Power Suppty Unrt General Purpose Stand SUPERSCOPE Handpiece (needs PSU) SCOPE·SK2-0IB SCOPE-SK2-02 SCOPE-SK2·03 SCOPE·SK2-04 SCOPE·SK2·05 SCOPE-SK2·06 SCOPE·SK2-06A SCOPE·SK2·07 SCOPE·SK2·08 SCOPE'SK2·09 SCOPE·SK2· 10 SCOPE·SK2· 11 A SCOPE·SK2· 12 SCOPE·SK2· 13 SCOPE·SK2· 14 SCOPE·SK2· 15 SCOPE-SK2· 11 B SS Tip 6.4mm Dual Flat SS Tip 3.2mm Conical SS Stainless Barrel SS Element SS Bead Retaining Nut SS Ceramic Bead SS Push Rod SS Push Rod Assembly SS Return Spring SS Flexible Lead SS Bakelrte Lock Nut SS Brass Nut SS Handle Body Only SS Swrtch Ring SS Rubber Grip SS Grommet Spring SS Grommet Nut SS Complete Handle /eg'rftltlmrs,ap, 50.30 1.50 1.50 8.95 1.50 0.40 0.20 7.70 10.20 1.20 10.70 3.25 2.80 7.15 3.60 0.95 1.85 3.60 20 .30 Tips for your Weller Iron are Weller WPA2 all $10.00 each Pyropen ~mm:~~ 1•~~~3}~~~:; The ultimate cordless soldering iron WELLER·PTA8 1.6mm 430d Sdriver Transformer powered low voltage soldering station. Features Weller closed-loop method of controlling maximum tip temperature to protect temperature sensitive components. • Grounded tip protects voltage and current sensitive components. I Ih I 48w I · I • const~i;i;~s see ea er • Non-burning silicon rubber cord • 15 tip sizes· 0.8mm to 6.00mm • 11secs to recover for 37'C drop • Choice of tip temperatures 315:cisoo:F, 370'C/70'Fi 430 C/800 F 155.00 • • • • • • No electricity No batteries Gas operated Ready to use in 30 seconds Refill _in moments . . h Hot air blower and mmi-torc burner .. • Up to 3 hours us_e from one filling Weller Pyropen weighs only 90gm and offers temperature co_ntr_ol from 200 lo 500' C • It has.a ~uilt,-m 1gn1tor and gas level md1cat1on.. Flame and temf;erature are eas1_ty controlled bys idmg lever. Choice of 14 tip shapes plus 4 gas/hot a_ir blowers. Can.be usecf for. brazing up to 1300'G with special tip. Supplied m metal storage box containing tip wipper. WELLER·PTAA61.6mm313d Sdriver WELLER-PT AA7 1.6mm 370d Spade WELLER-PTB7 2.4mm 370d Sdriver WELLER·PTB8 2.4mm 370d Sdnver WWEELLLLEERR··PTPTB B1 2._4 mmmm 3700dd Sppaaddee 43 5 888 2 4 WELLER·PTC6 3.2mm 315d Sdriver WELLER-PTC7 3.2mm 370d Sdriver WELLER·PTC8 3.2mm 430d Sdriver WELLER-PTCC7 3.2mm 370d Spade WELLER·PTF7 0.8mm 370d Con Rat WELLER·PTH7 0.8mm 370d Sdriver WELLER·PTH8 0.8mm 430d Sdriver WELLER-PTK6 1.2mm 31 Sd LSdriver WELLER·PTK7 1.2mm 370d LSdriver WELLER·PTKB 1.2mm 430d LSdriver WELLER·PTL7 2.0mm 370d LSdriver WELLER·PTLB 2.0mm 430d LSdriver WELLER-PTP6 o 8mm 31 Sd conical WELLER·PTP7 o•smm 370d Conical r65.90 WELLER·PTPB 0.8mm 430d Conical SC5000A DI:• ~\~~ ,, "'" •~·"" Desoldering Tool. 225.40 55.60 41.95 63.55 14.20 ~~ <('\ Now fitted with SOW heater. NEW Hot air nozzle makes rt easier to remove surtace mount devices. Price 1s unchanged at $399 ex tax 78 Stand ($4 \ ,,, SMD Removal i$-ii~6 Kit. Comes wrth filter pipe, stainless steel wire and blade rollshwire Miss E.A. December? holder, blade holder and at air Then send for 8 page FREE nozzle. Surts SC5000A and SC-700 . $82.80 Semiconductor Listing Geoff Wood Electronics Pty Ltd NEW SC-7000 DeSoldering Tool • Now with 1OOW ceramic heater • Work on up to 12 layer boards • Special antistatic housing e Optional surface mount krt $482.50 ex tax $579 inc tax Solder 1.25, 0.9 and 0.71 mm 250gm $7.95 500gm $14.95 Solder Wick $2.95 (Inc 1n N s W) 229 Burns Bay Road, (Corner Beatrice Street), Lane Cove West N SW Mail Orders to - P O Box 671, Lane Cove N S W 2066 Telephone: (02) 428 4111 Fax: (02) 428 5198 8.30am to 5.00pm Monday to Friday. 8.00am to 12 noon Saturday Mail Orders add $5.00 min to cover postal charges Next day delivery in Sydney ~dd $8.00 All prices Include Sales tax unless stated otherwise · Tax exemption certificates accepted if the line value exceeds $10.00 BANKCARD, MASTERCARD, VISA, CHEQUES or CASH cheerfully accepted. We take a look at Sony's new D-R If you thought that the CD ROM was just a clever toy with no real place to go, then think again. Now, more than ever, CD ROM brings a whole new world of information as close as your PC. By DARREN YATES Remember back to those grand old school days when you had to do those natural science assignments and you spent hours looking up books for information on all sorts of animals? Often you found one photo and only a couple of paragraphs of information when you had to write four pages! If you think about it, it's amazing how things have changed in just the last 10 years, let alone the last 50! The CD ROM makes it possible to store 680 megabytes of information on a single compact disc - or, in other words, a complete edition of the Encyclopaedia Brittanica from A to Z. But if that isn't your cup of tea, then what about desktop publishing, wildlife, history, music, engineering? - the list of titles now available for CD ROM is growing all the time in a wider area of subjects. So, when we were offered the chance to review the latest Sony package from Pelham Pty Ltd, it was a case of "who's first to play with it?" For just $1140, you can purchase everything you need to get their CD ROM up and running; from cables to the software and the CD ROM card. But of course, the whole package is useless unless you've got software to go with it. Fortunately, they've covered this end of the wicket as well by providing a package containing six discs, each in its own container. The titles included are Compton's Illustrated Encyclopaedia, National Geographic Society's Mammals, Languages of the World, World Atlas and CD Player Simulator software. This selection is claimed to be valued at over $3000. The CD ROM drive itself is very compact, measuring approximately 320 x 180 x 50mm, and it contains its own power supply so that it doesn't have to reply on the computer's supply. The front panel of the drive contains a thumbwheel volume control, the CD eject button and a 3.5mm stereo socket for a pair of headphones. A dualcolour LED shows when the CD is being accessed by the computer; orange for access and green for ready. Sony have done their best to make sure that installing the CD ROM is as easy as installing any other peripheral into your PC. They've even given you the corBoth the software & the hardware for Sony's CD ROM are easy to install. You can use it with just about any computer from an XT up, although at least an AT with a VGA monitor & driver card is recommended. 6 SILICON CHIP rect Phillips-head screwdriver to undo the computer case! The CD ROM card is a half-width unit that will fit into any expansion socket on an XT through to a 486. There are no DIP switches to set and it's very easy to install. The socket at the end of the card simply connects to either one of the sockets on the back of the CD ROM drive. After that, it's just a case of connecting up the power cable and you're ready to go. Installing the software The driver software for the CD ROM comes on a single 5¼-inch or 3½-inch floppy disc. All you have to do is load in the disc, type "llinstal" and press return. The installation software automatically loads in and then asks you what sections of the 6-pack CD-ROM software you wish to load into your hard disc. There's a very good reason for this, too. The demo program, which is a top-grade mix of high-resolution graphics and digital stereo sound, is about eight megabytes (8Mb) long and when you add that to everything else, the total comes to about 17Mb! Once you have decided on what software you want loaded in, the driver software prompts you to load in the correct CD and away it goes. When it's completed, it also automatically reboots your computer so that changes it has made to the CONFIG.SYS and AUTOEXEC.BAT files take effect. If you had enough room on your hard disc to load in the demo program, go to the LASERLIB directory and type "lldemo" and press return and you'll learn briefly how the CD ROM system works. Six-pack software As mentioned before, there are six CDs provided with numerous reference titles. To give you a taste of what you can expect, we'll take a brief look at a couple. To load in one of the CDs, you have to load it into a plastic caddy which then fits into the CD ROM drive. When you consider that some CD ROM drives now do without this caddy system and no CD players have it, you wonder why Sony has persisted with it. From our point of view, it was about the only negative feature of the whole package. But that aside, you only need to change discs when you change applications. CD music sampler Although not one of the bigger programs, this is one that is sure to be a hit in just about every workplace (including here in our editorial offices)! WHERE DO YOU GET IT? o~ (<,~ The unit is supplied complete with six CDs, including Compton's Illustrated Encyclopaedia, National Geographic Society's Mammals, Languages of the World, World Atlas and CD Player Simulator software. QLD'S LARGEST SUPPLIER OF MICROWAVE OVEN PARTS & ELECTRONIC COMPONENTS REPLACEMENT PARTS DISTRIBUTORS FOR • A SHARP Panasonic AKAi e TV e CAR STEREO e VCRs e STEREO e BUSINESS EQUIPMENT e WHITEGOODS e PHONES e VIDEO CAMERAS e MICROWAVE OVENS A RANGE OF MAGNETRONS, DIODES, CAPACITORS & SHEET MICA TO SUIT MANY MODELS & BRANDS OF MICROWAVE OVEN lf ffi EDSON FIELD PTY LTD (A.C.N. 010 378 588). Trading as: ECONOMIC ELECTRONICS, 24 Campbell Street, Bowen Hills, Old 4006. PO Box 481, Fortitude Valley, 4006 Telephone (07) 252 3762. SOUTHPORT ELECTRONIC SHOP, Shop 1/ 10 Welch St, Southport, Old 4215. Telephone (075) 32 3632 Fax (075) 51 0543 I VlSA I e VAST RANGE OF COMPONENTS e TEST EQUIPMENT e TOOLS e SOLDERING EQUIPMENT e DATA BOOKS e AUDIO/VIDEO ACCESSORIES e CABLE & CONNECTORS MAY 1992 7 You can now afford a satellite TV system 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: $995.00 These two off-screen shots are from the National Geographic Society's Mammals & from World Atlas. Here's what you get: * A 1.8-metre prime focus dish antenna, complete with all the mounting hardware. This program allows you to play your favourite music CDs through your CD ROM and even has a VGA screen display of one of Sony's CD players, complete with shuffle play, repeat and all the standard CD player features. But the best thing from a work point of view is that the software is clever enough to be able to play your CDs in the background while you get on with other work on the computer. That's pretty clever stuff. And what's more, the sound quality is just as good as from any conventional CD player. Sony even provide you with a pair of stereo headphones that plug straight into the front of the CD ROM for private listening while you work. * One super low-noise LNB (1.4dB or better). *magnetic One Ku-band feedhorn and a signal polariser. * 30 metres of low-loss coaxial cable with a single pair control line. * lnfrared remote control satellite receiver with selectable IF & audio bandwidth, polarity & digital readout. Your receiver is pre-programmed to the popular AUSSAT transponders via the internal EEPROM memory. This unit is also suitable for C-band applications. Call, fax or write to: AV-COMM PTY LTD PO BOX 386, NORTHBRIDGE NSW 2063. Phone (02) 949 7417 Fax (02) 949 7095 All items are available separately. Ask about our C-band LNBs, NTSCto-PAL converters, video time date generators, FM 2 & EPAL & Pay TV hardware. I I II ----------Name ...... .. .... ... .. ... .. .. ............... ... .... I I II I Address ........... ... .. ........ ... ...... ...... ... . I I ........................... P/code .... .. ..... ..... II Phone .... ...... .. ..... ....... .... ...... ..... ....... I I I II YES GARRY, please send me more information on K-band satellite systems. . ___________ .I I 8 ACN 002 174 478 SILICON CHIP 01/92 CD player software, you'll hear a myriad of animal sounds in both ears. CD ROM catalog National Geographic Also included in the "6-pack" is a CD ROM catalog which shows the CDs currently available from Sony. The list is truly diverse and includes, among other things , an aircraft registration compendium, Battle Chess , CIA World Fact Book, Variety's Video Directory, Shakespeare on Disc and Coate's Art Review. They're priced at between $80 and $500, depending on the application. One CD contains the complete 26volume edition of Compton's Family Encyclopaedia with over 32,000 articles, 1500 illustrations and sound recordings. What's more, you don't have The most spectacular package comes from the National Geographic Society. Called "Mammals " the program contains information on over 200 mammals, all complete with full colour photographs. But this is where the CD ROM leaves books behind. Also included are sound recordings and real life footage from some of the National Geographic films on a large number of mammals. You can even get a printout of the information provided on a particular screen by clicking on the PRINT tile. To be able to store so many audio recordings of the mammals shown, the right and left channels contain different tracks. For example, when you listen to what an old-world monkey sounds like, the sound is reproduced in the left ear. If you listen to, say, a moose later, you may hear that in the right ear. If you play the Mammals CD via the The CD is placed in a plastic caddy before being inserted into the player. to flip through reams of pages; instead, you just follow the pathways to the particular subject of interest. Again, the same method of storing so many sound tracks has been used here. If you play this disc through the CD player software, you'll hear two separate tracks in both right and left ears. The program, of course, only allows you to hear the sound recording of interest. Play CD's On Your Computer World Atlas One way to help with geography assignments is to have a good atlas and this CD ROM system has one. It gives you a picture of the world and by using either the keyboard or a mouse, you can select any region of interest and it will display that almost instantly on screen. You can then select any country from that particular region and look at it more closely. Overall, the CD ROM system allows you to instantly access a whole world of information previously only available at large reference libraries. As a teaching tool, it provides students and teachers alike with fast, instant information on the latest topics from music, science, art, biology, history and geography - the list goes on. With the way that CD ROM is expanding, it won't be long before you can buy the software as easily as you can buy music CDs. The Sony CD ROM package from Pelham is areal winner. At only $1140, it represents terrific value for money, particularly when you consider the amount of information being made available and the current cost of many of the reference works provided. Although many of the CDs available use high-resolution VGA graphics, many CDs also support CGA and EGA standards as well and there are plenty that don't even require graphics cards. So there are lots of good reasons to consider a CD ROM for your computer. If that doesn 't interest you, think of the complexity of the games that will be possible - at the very least, you should get digital stereo sound and motion picture graphics. The system reviewed here comes complete with drive, CD ROM card, installation software, the "six pack" reference library, CD cassette tray, cables, headphones, screwdriver and user manuals. The system require- THE LATEST MULTIMEDIA SENSATION ..... CD-ROM YOU GET ... •3 - • Textual Information • CD quality audio sounds • Photographic Images • Motion Video • SOUND BLASTER PRO Short Version SENSATIONAL CD TITLES Creative's Sounds Microsoft Windows 3.0 Microsoft Bookshelf, includes Atlas, Encyclopedia & more! Cat X-2250 DISK STORAGE BOXES 5.25" Holds 50 disks Cat X-3531 5.25" Holds 100 disks Cat X-3534 Mini IBM Joystick Cat X-3581 For more information on your nearest store location Phone: (02) 888 3200 PHONE ORDERS: SYDNEY AREA 888 2105 OUTSIDE SYDNEY (FREE CALL) 888 22 6610 81319 DICK SMITH (WHOLESALE) A.C.N. 000 908 716 ments are an XT or AT personal computer, 512Kb RAM minimum,' DOS 3.1 or higher, a hard disc, and a VGA card and monitor (recommended). For more information, contact Pelham Pty Ltd on (02) 980 6988; or see them at 1st Floor, 100 Yarrara Rd, Pennant Hills, NSW 2120. SC MAY 1992 9 · 3 year warranty! OPTIONAL EXTRAS ADD PRICE TO BASE SYSTEM COST. lM VGA CARD .. $150 512K VGA CARD .. $50 TO CHANGE A 85M HARD DRIVE TO A 126M HD add $175 105M HD .. $105 200m HD add $675 ISOM HD .. $575 (286-21 80286-16 CPU ._______...__ 1 MEG RAM EXPANDABLE TO 4 MEG 21Mhz LANDMARK SPEED TEST 1.2M JAPANESE BRAND F.D.D 85M HARD DISK DRIVE 28ms ACCESS 101 EXTENDED "CLICK .. KEYBOARD JAPANESE KEYBOARD SWITCHES MINI CASE & 200W POWER SUPPLY SUPA VGA COLOUR MONITOR (1024 x 768 Res) 0.20•• DP 2 SERIAL, PARALLEL, GAME PORTS 3 YEAR PARTS & LABOUR WARRANTY 256K VGA CARD. IBM' COMPATIBLE SPREADSHEET, WORDPROCESSOR & DATABASE SOFTWAREINCLUDED. NEW 286-25/31 $1 , 549 TAX INC. $1595 80386SX-16 CPU 1 MEG RAM EXP TO 8 MEG 21Mhz LANDMARK SPEED TEST 1.2M JAPANESE F.D.D. 512K VGA CARD 85M HARD DISK DRIVE, 101 EXTENDED "CLICK" KEYBOARD MINI CASE & 200W POWER SUPPLY SUPA VGA COLOUR MONITOR 1024x768 Res 0.28""DP SERIAL PARALLEL GAMES PORTS 3 YEAR PARTS & LABOUR WARRANTY IBM' COMPATIBLESPREADSHEET, WORDPROCESSOR & DATABASESOFTWARE INCLUDED. TAX • SHAREWARE SOFTWARE ' INC. ASSEMBLED & TESTED $1 695 EXTRA RAM 1 MEG add .. $75 2 MEG add .. $150 DOS 5.0 AN EXTRA ....................... $100 DR DOS 6.00.$129 WINDOWS 3.00.$129 SOUND CARDS SOUND COMMANDER ..................... $149 THUNDER BOARD .......................... $199 SOUNDBLASTER II ......................... $249 SOUNDBLASTER PR0 ..................... $389 FLOPTICAL DRIVE add ................... $849 21 M/BYTE DISC TO SUIT............... $39 CD ROM DRIVE ............................... $795 RITRON RITRON ( (3~6SX-31) 80386SX 25M CPU 1 MEG RAM EXP TO 8 MEG 31Mhz LANDMARK SPEED TEST 1.2M JAPANESE F.D.D. 512K VGA CARD 85M HARD DISK DRIVE, 101 EXTENDED ""CLICK .• KEYBOARD MINI CASE & 200W POWER SUPPLY SUPA VGA COLOUR MONITOR 1024 x 768 Res 0.20•• D.P SERIAL PARALLEL GAMES PORTS 3 YEAR PARTS & LABOUR WARRANTY IBM' COMPATIBLESPREADSHEET, WORDPROCESSOR & DATABASESOFTWARE INCLUDED. 'SHAREWARESOFTWARE ASSEMBLED & TESTED IN AUSTRALIA. EXECUTIVE EXECUTIVE $1 _ 749 ' TAX INC. ( /.3~~-65 >v 386-57) 80386-33 CPU 64K CACHE ON BOARD MEMORY 1 MEG RAM EXP TO 16 MEG 57Mhz LANDMARK SPEED TEST 85 MEG HARD DISK 1.2M JAPANESE BRAND F.D.D 101 EXTENDED "CLICK" KEYBOARD SERIAL PARALLEL GAMES PORTS SUPA VGA COLOUR MONITOR (1024 x 768 Res) 0.28" DP MINI CASE & 200W POWER SUPPLY 512K VGA CARD (256 COLOURS) IBM' COMPATIBLE 3 YEAR PARTS & LABOUR WARRANTY SPEADSHEET, WORDPROCESSOR & DATABASE SOFTWARE INCLUDED. ' SHAREWARE SOFTWARE ASSEMBLED & TESTED IN AUSTRAUA. $2 095 ' TAX INC. EXECUTIVE (486-157.>) 80486·33 CPU 256K ON BOARD CACHE. 1 MEG OF RAM 157Mhz LANDMARK SPEED TEST 85 MEG HARD DISK 1.2M JAPANESE BRAND F.D.D 101 EXTENDED "CLICK"" KEYBOARD SERIAL, PARALLEL, GAMES PORTS 512K VGA CARD. IBM' COMPATIBLE SVGA COLOUR MONITOR (1024 x 768 Resolution) 0.28""DP MINI CASE & 200W POWER SUPPLY 3 YEAR PARTS & LABOUR WARRANTY SPREADSHEET, WORDPROCESSOR & DATABASE SOFTWARE. ASSEMBLED & TESTED IN AUSTRALIA. ' TAX INC. WITH 200 MEG DRIVE $2,945 TAXINC. $2,450 TAX EX. $2,895 $2,495 WITH 200 MEG DRIVE TAXINC. TAX EX. ROD IRVING ELECTRONICS Est. 1977. MAIL ORDER HOTLINE: 008 33 57 57. ORDER FAX LINE: (03) 543 4871 ENQUIRES (03) 543 7877 HEAD OFFICE: 56 RENYER RD, CLAYTON. PH: (03) 543 2166. FAX (03) 543 2648 CITY 48 A.BECKETT ST. MELBOURN E. PH. (03) 6391640. FAX: 6391641. OAKLEIGH: 240C HUNTINGDALE RD, OAK LEIGH. PH: (03) 562 8939 FAX: (03) 562 8940 NORTHCOTE 425 HIGH ST. NORTHCOTE, PH. <189 88M. FAX: 489 8131. SYDNEY:74 PARRAMATTA RD, STANMORE. PH : (02) 519 3134. FAX: (02) 516 5024 BLUESTAR COMPUTERS: 271 MAROONDAH HWY, RINGWOOD, PHONE: (03.) 870 1800 FAX: (03) 879 3027 115 - 117 PARRAMATTA RD CONCORD. PH: (02)'744 5526 FAX : (02) 744 5405 $2,395 ~:; WITH 200 MEG DRIVE $2,895 TAXINC. $2,495 TAXEX. TAXEX. RITRON EXECUTIV RITRON $ 2 195 ASSEMBLED & TESTED IN AUSTRALIA. $1,995 386-33 12BK..... $2195 80486SX-20 CPU 1 MEG RAM EXP TO 32 MEG 75Mhz LANDMARK SPEED TEST 85 MEG HARD DISK 1.2M JAPANESE BRAND F.D.D 101 EXTENDED ··cLICK"" KEYBOARD SERIAL, PARALLEL, GAMES PORTS, 1MEG VGA CARD SUPA VGA COLOUR MONITOR·(1024 x 768 Res) 0.28" DP MINI CASE & 200W POWER SUPPLY 3 YEAR PARTS & LABOUR WARRANTY SPEADSHEET, WORDPROCESSOR & DATABASE SOFTWARE INCLUDED. 'SHAREWARE SOFTWARE 80386-40 CPU 64K CACHE ON BOARD MEMORY 1 MEG RAM EXP TO 16 MEG 65 Mhz LANDMARK SPEED TEST 126 MEG HARD DISK 12ms ACCESS TIME 1.2M JAPANESE BRAND F.D.D 101 EXTENDED ··cLICK" KEYBOARD SERIAL, PARALLEL, GAMES PORTS 512K VGA CARD SUPA VGA COLOUR MONITOR (1024 x 768 Res) 0.20·· DP MINI CASE & 200W POWER SUPPLY 3 YEAR PARTS & LABOUR WARRANTY SPEADSHEET, WORDPROCESSOR & DATABASE SOFTWARE INCLUDED. 'SHAREWARE SOFTWARE $3,595 $2,995 TAX INC <at>4.E362t.57 c 80486-33 CPU 256K ON BOARD CACHE. 4 MEG OF RAM 157Mhz LANDMARK SPEED TEST 200 MEG HARD DISK 12ms ACCESS TIME 1.2M JAPANESE BRAND F.D.D 3.5" 1.44M JAPANESE BRAND F.D.D 101 EXTENDED "CLICK" KEYBOARD SERIAL, PARALLEL, GAMES PORTS 1 MEG VGA CARD. IBM' COMPATIBLE SUPA VGA COLOUR MONITOR (1024 x 768 Res) 0.28"" DP TOWER CASE & 220W POWER SUPPLY 3 YEAR PARTS & LABOUR WARRANTY SPEADSHEET, WORDPRCESSOR & DATABASE SOFTWARE. ASSEMBLED & TESTED IN AUSTRALIA. IDEAL CAP MACHINE! ' TAX INC. TAX EX FREIGHT CHARGE BASED ON 35KG COMPUTER SYSTEM Melb-Metro.$12.00 Sydney....... $17.00 Adelaide .. ... $17.00 Bribane ...... $24.00 Canberra .... $18.00 Darwin ........ $40.00 Perth. •••...•... $31.00 Tasmania •... $53.00 Vic country.... $19.00 NSW country.$39.00 S.A country..• $39.00 OLD country.$55.00 W.A country.• $74.00 lnsurance:$1 / $100 Value. $ 3 99 5 $3,395 TAXEX. All sales tax exempt orders to : RITRONICS WHOLESALE 56 Ronvor Rd, Clayton, Victoria. Ph: (03) 543 2166 Fax: (03) 543 2648 MAIL ORDER & CORRESPONDENCE P.O BOX 620, CLAYTON, VICTORIA. 3168. Error• & ommlnon, excepted. Prtcn & apeclflc1tlons eub/eet to change. "IBM, PC, XT, AT, are registered trademark ■ of lntem atlonal BualneH Machlnee. PRICES AT AUS S ■ US $0.74 1·9 boxea 10+ 31/2"DD $19.95 3 1/2"HD $45.95 5 1/4"DD $14.95 5 1/4"HD $23.95 ETIME WARRANTY 50+ $4.30 $8.10 $7.50 $13.50 100+ $3.25 $7.50 $7.00 $12.00 SOO+ $3.95 $6.90 $6.60 $11 .00 ~ RS232 2WAY.......... ........ $39 RS232 4 WAY.................$59 RS232 X OVER .............$59 RS232 2 WAY A UT0 .....$69 CENT RO NICS 2 WAY... .$39 CENTR ONICS X-OV ER .$59 CENT RONICS 2 WAY A UTO.$69 CENTRONICS 4 WAY.$69 D89 + 5 PIN DIN ....$69.95 VGA KEYBOARD SWITCH BOX 2 WAY............... ...... $59.95 4 WAY...................... $69 .95 9 PIN SWTCH BOX 2 WAY.................... .$49.95 4 WAY..................... $59. 95 10+ 3 3 5 5 1/2"DD $28.50 1/2"HD $53.50 1/4"DD $22.95 1/4"HD $27.95 NEW CATALOGUE OUT NOW! NEW SWITCH BOXES VIDEO SWITCH BOX $18.95 $42.95 $12.95 $22.95 MOTHERBOARDS $27.95 $52.50 $21.95 $26.95 3 1/2"DD $23 .95 3 1/2"HD $39.95 $ 5 1/4"DD $12.95 $ 5 1/4"HD $19.95 $ PA COLOUR MONITOR 3 YEAR WARRANTY c::::::::::v"""" 286-12/16 .............ir...·=··················$1 09 286-16/21 ........... ._j -~·,,.--,. •· ........$159 This stylish & reliable monitor has been 386SX-16 ........... · ,. .......$295 designed for Australia n conditions and 1 386SX-20/27 ..... •• , •.•':::::: :'. . . . . . . . . $325 comes with a 3 year warranty. 386SX-25/31 ................................... .$350 , Spees: CTR: 14" 90° delection, dark tint, 385-25 .............................................. $525 non glare. 386-33 64K CACHE......................... $645 Display Size : 245 +/5mm x 180+/-5mm x 386-33 WITH 128K CACHE ............$749 180+/•5mm 486SX·20 .........................................$895 Resolution: (max): 1024 x 768 486·33 256K CACHE....................... $1295 Dot Pitch: 0.28" ...... $469.00 SOUND BLASTER II With FREE speakers The ultimate sound card that plugs into ant internal slot in your IBM or compatible • Spech to text syntheseizer & more........ $229 • • SHORT OF SLOTS? . SOUND BLAST R PRO 16 Bit Card • RCA Aud io cable • Midi Cables • 5.25" & 3.5" diskettes • CD music player & much more .....•...... $469 "NEW" IBM VGA-COMPATIBLE VIDEO GRAPHICS CONTROLLER Comes complete with : , VP442 Card • Users Manual , 2 Diskettes (driver & ut ill ity) • Two 10 to 9 /25 interface cable for COM 1 & COM 2 , 34 way Flat cable for FOO • 40 Way flat acble for IDE • 16 to 15 interface cable for GAMES PORT. X18066 .....................................................................$139.00 SAVE ON OUR GREAT RANGE OF EPSON PRINTERS Matr i x, 180 Cps Dr aft 30 Cps NLO, Pu ll Trac tor C22054 ................... $249 LX·SS O 80 Co l. 9 Pin Do t Malrix , 240 Cps Dr aft LQ •860 80 Col. 24Pi n Doi Matrix• 295 Cps Drall.98 CPS LO. Colo ur SQ -25S0 BO Col , 24 Nozzel LX•40 0 80 Co l. 9 Pin Do t tQ~ i nk jet, 600 Cps Draft, 198 Cps LO, Push Tractor, Smart Park Featu re , Standa rd,Push Tractor Smart Park Feature ................................... $1095 ..............$1995 LQ-1070 136 Co l. 24 Pin Dot Matri x, 252 Cps Draft, 84 Cps LQ •400 80 Co l. 24 Pin Do t 48 Cps NLQ, Pu sh Trac tor, Sm art Park i-:ea tu re Matrix, 180 Cps Draft , 60 NL O NLO, Scal ab le Fonts, 8 to 32 Pull Tractor po int, 11 LO Fon ts, 360 x 360 C22074 .................... $3 65 C22070 ..................... $4 39 FX· SSO 80 Col. 9 Pin Dot Ma trix , 264 Cps C'r a h LQ-570 80 Co l. 24 Pin Dot Matrix, 252 Cps Draft, 84 54 Cp s NLO Pu sh Trac tor Sm art Pa rk Fe&ture Cps . NLO Scalable Fonll 8 to 32 points, 11 LO Fonte 360 x 360 DPI. Top. Rear• Bottom and Fro nt paper ...$750 FX• 1050 136 Col. a Pin Dot Ma trix. 264 Cp s Draft. 54 Cpa NLQ, Push Tr1ctor1 Smar t Park Fea tura. ·•· ··•· ·....... .................... .. $925 SQ •85 0 80 Col. 24 Nozzo l Ink GOO Cpl Dri ll. 1118 Cpl LO. Pul h Trac tor. Smut Pe rk Foaturo. i••· .................................... $1, 225 DPI, Top, Re ar, Bottom, and Front Paper Feedpaths, Convenable Push/Pu ll Tr actor ·························· ..............$775 LQ• 1170 136 Col. 24 Pin Doi Matri x. 350 Cps Drafl. 110 Cp1 NLO. Sc1l1ble Fonll. 8 to 32 poin~ 11 LO Fonll. 360 x 360 DPI. Top. Rear. Bottom. I nd Front Poper Feedp1th 1• Convel1 oble Pu 1h/Pull Troctor feed pa th,, Con vertable Pu1h/Pull Tr1e1or. .................................. $575 ........................................ $1,149 LQ•870 80 Col. 24 Pin Dot Motrlx.330 Cp1 D,.fL 110 Cp1 NLO. Scalab le Fonta. a to 32 pol n11. 11 LO Fon11 . 360 x 360 DP I. Top. R11r. Bottom. & Fro nt pop11 FNd palhl Convtrtlbll Pu1h/Pull Tractor . LQ•l 060 138 Col. 24Pln Dot Matrix' 292 Cp1 Drott, 98 ;;pa LO. Colour Standard.Pulh Tractor. Sm1J1 Park Future. ............................................ $1,395 ...................................... $895 LQ•2550 138 Col. 24Pln Dot Matri x' LQ •200 60 Col. 24 Pin Dot Matrix 192 Cpa Drafl. 84 LO. Pu ll Tractor. a Bit Mop lonll. 400 Cp1 Draft, 133 LQ Colour Sta ndard.Pulh Tractor. Sm111 Pa rk F11turt • .......... .................. .............$475 • ACN.005 428 437 HE.AD OFFICE: H RENVER RD, CLAYTON. PH: (03) 543 21H. FAX (03) 543 2848 CIT'i 48 A•BECKETT ST. MELBOURNE. PH. H3 8351 / 8381840. FAX: 8381841. OAKLEIQH: 240C HUNTINQDALI! RD, OAKLEIQH. PH: 582 8838 . NORTHCOTE 425 HIQH ST. NORTHCOTE, PH. 488 88H. FAX: 488 8131 . IYDNl!Y:74 PARRAMATTA RD, STANMORE. PH: (02) 519 3134. FAX: (02) 519 3888 BLUESTAR COMPUTERS: 271 MARCCNDAH HWV. RINGWOOD. PH: (03) 170 1800 .........................................$ 2,049 Po1tag1 r1t11 ., ............ u.oo Tit•• ,....,. . 10 • f24.99.,'3.50 11ltllN bHII '21 • '49.99 .. '4.50 potltge only 11P •• '50 • "9.99 .. H.OO : •::,i:lgh~ ,100 • ,199 .... 7.00 llomt wtNIla :~lty ,200 • 8100... FREE 8100 PLUI .. FREE oharg• ~ 11111-t 11 • 1 HO ~ WELLER SOLDERING STATION ~ c ·~ with temperature controlled soldering iron. I~-· CD ROM DRIVE UNIT \Q·~),C::~,:./ A tramsformer powered soldering station, complete with a low voltage, temperature controlled soldering pencil . The special Weilar "closed loop" method of controlling maximum tip temperature Is employed, thereby protecting temperature sensitive components while the grounded tip protects voltage and current sensitive components. The soldering pencil features a stainless steel heater construction, a non-burning silicon rubber cord and a large selection of iron plated tips in sizes from 0.8mm diameter to 6.0mm diameter with a choice of tip temperature of 315° C/600°F, 370° C/700° F and 430° C/800°F. r12soo Usually $179.00 This month o nly $129.00 ioouble your disk .storage with .... .•. -g . a Open up a whole new world of sight and sound user interaction with a CD-ROM Drive Unit You have never seen such a wealth of lnfomation and entertainment with audio and visual response that will truly astound you. You can even play and listen to your audio CD'S while continuning to use your computer The world of the CD-ROM makes available to you over 1,500 CD-ROM Titles produced by more than 1,800 companies which support this fast growing information and entertainment facility.Comes complete with CD ROM DRIVE UNIT, controller card for installation In an IBM PC.2 SPECIFICATION PERFORMANCE Disc diameter..............................12cm Disc speed .................................. 200-530rpm (CLV) Da!a capaclty.. .............................540 MBytes Da!a transfer Rate Sequentlal..1 SOKBytes/sec. (Mode 1) 171 KBytes/sec. (Mode 2) THE POWERMATE "GREAT 8" DR DOS 6.0 The most advanced, fully DOS-compatible operating system available today. lt•s everything you need to nm your DOS, Windows, and networking applications faater. Maximize hard disk performance, keep your system and Data secure, and make your PC easier to use. DISK MAX: Improves your pc•s overall performance so you can get more work done In less time. lta optional automatic file compression feature potentially doubles your hard disk storage space. MEMORY MAX: moves ·DR DOS buffers, drivers, TSRs and networking software outside the 640K memory area, leaving more memory for your DOS, Network and Windows applications. Ideal for the garage or home. The Powermate "Great 8" has 8 outlets for all types of appliances plus ii provides extra safety. It has Overload protection. If it is overloaded (operating appliances that totally exceed 2400 watts or 1 O amps). The overload swlch will trip, automatically turning off all appliances plugged Into the Powermate. If it does overload you simply push the reset bullon THIS MONTHS PRICE IS THE LOWEST YET!.. ...... P18044 .......................................•...••.........•. ........ $39.95 CITIZEN™ PN48™ $99.00 and power ls restored. lH\5 MON1~ -!,~~-·;:·~-=::::=::=====:,7' 4164-10 : .: : ~,~ o~ : : : : :,::~~~s,: :,e__:_te-rs-. Z• The PN48 Notebook Printer Is the first printer I that is every bit as portable as the new· notebook • ·· · computers. Weighting approximate ly two pounds ■ without the battery (2 1 /2 pounds with the battery), you can add the PN48 to your portable office and hardly know it•s there. PN48 FEATURES: Despite the remarkable small size (11 518" x 3112"), the PN48 is the worlds first truly portable laser quality printer, offering the same versatility and superior printing quality made famous by other Citizen printer. The Notebook Printer is compatible with Citizen CSX- aeries 24-wire printers. Has two built'i n fonts, Roman and Courier; five pitch selection; and the ability to print on overhead projector transperancies. You will find the PN48 easy and fun to use. 1t•s simple to operate, connecting your computer Is a snap, and both print cartridges are designed for long and dependable trouble free wear. • Graphic resolution as high ea 360 x 360 dpi: C22199 ........................................ $699 1Mx9 ;) CORDLESS / ELEPHONE AUS ~/ ~ ,K----....-::~ G ~---- .- .· FEATURES: • Full Two-way Intercom • Paging • User Selectable Security Coding • Tone/Pulse Switchable • Last Numder Redail • In-use Indicator • Automatic return lo standby mode when remote phone is in charge A94200 ........................was $17Q,QQ Special MAY price $169.00 Speed (ns) No. of pins 1-9 100 (64K X 1) $4.95 80 (4 X 64K) $6.95 41256-08 (256K X 1) 80 $3.95 44256-07 70 (256K X 4) $9.95 lM-10 (1Mx 1) 100 $10.95 lM-08 80 (1Mx 1) $12.95 Speed (ns) SIMMS 1-9 10+ 256K X 9 80 $21.00 $19.00 1M x 9 80 $79.00 $75.00 1M x 9 70 $79.00 $75.00 1-9 10+ 4M X 9 80 $295.00 $275.00 Speed (ns) SIPPS 1-9 10+ 256 X 9 80 $21.00 $19.00 1Mx9 80 $79.00 $75.00 ) 4464-08 70 $79.00 $75.00 10+ $4.50 $5.95 $3.50 $8.95 $9.95 $10.95 100+ $2.90 $3.50 $2.50 $8.50 $7.95 $8.95 100+ $18.00 $69.00 $69.00 25+ $250.00 500+ $16.00 $59.00 $59.00 100+ $18.00 $69.00 500+ $16.00 $59.00 $69.00 $59.00 1000+ $2.25 $2.95 $1.95 $6.95 $7.50 $7.50 CODE-A-PHONE PERSONAL ANSWERING MACHINE FEATURES: •"BEEPLESS" Remote Control • Call Screening • One-Touch Message Playback • Personal Memo Record • Voice-Activated Recording • 10 Number Speed Dailing • Power-Fail Security • Digital Message Counter • Fast Forward Rewind • Built-in Microphone • Ring Selector MESSAGE LIGHT MESSA GE COUNTER 7 ,... STOP ~ MESSAGES RINGER _ Auro..J i , NN REC - o1ALPA0 iuNoeR cAssene cov A94150 ............... was $~QQ.QQ LNO J , o,REcrosv Special MAY price only $1.79.00 .• . . - .- ' ·' . ST·UDE.NT .SOFTW,AR.:E. PAC-KAG.ES WORDPERFECT WINDOWS .. If your a FULLTIME student MS WORD WINDOWS .......... .. or teacher with current MS EXCEL WINDOWS ........... . CORAL DRAW........................ . identification from the VENTURA PUBLISHER ......... . education institute you DBASE IV................................• attend, you can take BORLAND C++ ....................... . advantage of these great BORLAND C++ prices on this popular WITH APPLICATIONS ............ . software! ADL,US PAGEMAKER ............ . GET INTO THE PICTURE WITH THE MAESTRO . 9600XR FAX/ DATA MODEM . . J • - SPECIFICATIONS V29 / V27 ter / V21 Ch.2 Fax modes V22 bis V22 / Bell 212A 103 Data modes Auto dail, Auto Answer, Pulse and Tone Dialing, Hayes "AT' compatible, TR.29 fax mode compatible (industry standards), Fax group 3 compatible (send and recieve), Auto Baud select, All new dsp technology, External modem-RS232 compatibles and Apple Macintosh. MAESTRO 2400XR MODEM This is our biggest selling external modem that features• V22 bis, V22 , V23 (with auto BRC), V21· (2400bps, 1200bps, 12oonsbps, 300bps) Auto Baud Select, Hayes "AT"·commands set, Auto Answer, auto Dial, Auto Disconnect. This modem will suit almost any computer with a RS232 serial port. Telecom approved. 2400bps for only $389.oo This has to be the cheapest and easiest way Into high speed data communications with features only found .i n some moderms of at least twice the price. Features include-2400bps (V22bis), 1200bps (V22), Auto answer, Auto dail, Auto disconnect, Hayes "AT" commands set compatible, Non volitile memory (for configuration storage), Synchronous and Asynchronous operations Telecom approved $289.oo full price incl. tax "MegaRAM" Memory board This new generation memory enhanced board offers O wait state high speed operation . • It takes• up to 6M Bytes of 4 x 256K or 1 x 1 M DRAM chip. Up to seven cards can be used together (42M B EMS). It is 100% EMS 3.2 & 4.0 compatible, and best of all it can be used in an XT, AT or 386 because it is 8 bit, 16configerable. So get yourself a Mega tor the price of a mini. x1aos1 .. .............. ......... SAVE sso.oo........... $249.oo $210.00 $.290.00 $296.00 $399.00 $395.00 $295.00 $235.00 ..._ $285.00 $395.00 AUVA NOTEBOOK The Ritron 945/20 takes up less space than your old desktop when you 're working and can be stored in the drawer of your desk when you're finished. The 945/20 uses less than one third of the space of your desktop SX and Is at least as powerful. Don't stretch your arms to their limit walking back to the office. The Ritron 945/20 wont drag you down when you need to be on• the•go Relax over a cup of coffee and do some power computing in a more elegant setting than your office. The Ritron 945/20 lets you work in your favorite places without intruding on everyone around you. Microprossor 'CPU 80386SX·20 Memory 'Fitted with 4MB BIOS '128KB ROM Pheonix BIOS Storage Devices 'One 1.44MB 3.5" Floppy disk· drive ' Ona 60MB 2.5" Hard Disk Drive Display 'VGA compatible display '640x480 pixel res olution '32 gray scales •Backlit Paper White LCD INCLUDES DOS 5 OR DR DOS 6.0 ALL FOR ONLY $2895 1nc. Tax $2495 Tax Ex. 4 PORT SERIAL CARD (Software Output Cables included) The PE. 514 has 4 port serial ports for asvnchronous communication. These ports can bve used to connect your PC with a serial printer, MODEM, Serial mouse or serial devices which use an RS232C interface. The interface Is a DTE type with a male DB25P for 4 serial port output. It supports DOS & XENIX. X18155 ...............................,...... $199.00 =:;===============================::; ;:;;:;:;;:;::~;:::::;;:;;;==============-=======:::::.... ,~i,~~~ °;~;;~::~\ m~~i~i::RDc~ scanner that can transfer graphic :Jl.RJi:1 ~• .:·___)···· images such as photographs, drawings, - - - ~ ~ text and clip art d irectly to your computer screen. It Js capable of scanning up to 105mm in two ditterent modes, Letter or Photo. The GS-4500 also has a resolution control switch lo select Iha amount of brightness to be used. It also can control Iha amount of colour shade. Tha letter mode scans black and white This mode can be used for artwork and scanning text lo a text file using OCR software. X19935 ................................ $279.00 ~ The ULTRA 15C provide• Intelligent caching up to 16 MBytee of cache memory to make the drive "lnvl1lble" when a cache hit le achieved providing multiple lncre11e1 In 1/0 performance. It lo AT regieter & BIOS compatible. It 1upport1 two high transler IDE drive,. It 1upport1 the lergeet ■e lection of hard drlveo In the m,rket today. The ULTRA 15C 1110 aupporll any mix (s. 25.. and 3.5") of up to three floppy dlek drlveo or floppyt ■ pea. In addition to the apeclal oupport to break the oupport to break the 1024 cylinder and the 528MB partition limit■ of DOS ind OS/2, the ULTRA family of caching controllero will 1 110 co-reolde with any other controller to aupport dual channel• and/or duplexing/mirroring in popular network operating ayateme. ty. t . •············•·•···•••••·········•··· .. ROD IRVIN ACN.oos 428 437 HEAD OFFICE: 56 RENVER RD, CLAYTON. PH: (03) 543 2186. FAX (03) 543 2648. CITY 48 A'BECKETT ST. MELBOURNE. PH. (03) 663 6151 / (03) 639 1640. FAX: (03) 6391641. OAKLEIGH: 240C HUNTINGDALE RD, OAK LEIGH. PH: (03) 562 8939. FAX:,(03) 582 8940. NORTHCOTE 425 HIGH ST. NORTHCOTE, PH.(03) 489 8868. FAX : (03) 489 8131. SYDNEY:74 PARRAMATTA RD, STANMORE. PH: (02) 519 3134. or (02) 565 1458. FAX: (02) 516 5024. BLUESTAR COMPUTERS: (COMPUTER PRODUCTS ONLY) 271 MAROONDAH HWY. RINGWOOD. PH: (03) 870 1800. FAX: (03) 879 3027. OPENING 6th OF APRIL: BLUESTAR COMPUTERS CONCORD. (COMPUTER PRODUCTS ONLY) GROUND FLOOR 115-117 PARRAMATTA RO, CONCORD. PH: (02) 744 5528. FAX: (02) 744 5405. TOLL FREE MAIL ORDER HOTLINE: 008 33 5757. FAX ORDERS: (03) 543 2648 (STRICTLY ORDERS ONLY) $649.00 ::a . , 195mm length H10542 ....................... $15.50 , 200mm length H10543.......................$15.90 • 225mm length H10546 ....................... $16.90 • 300mm length H10560 .......................$19.00 , 1 metre length H10565 ....................... $49.95 • 2 metre length H10570 ....................... $95.00 10+ P10525 ............$7.95 $6.95 6N138 ·OPTOCOUPLERS Z11660 ..................... $6.95 CANON LASER CARTRIDGES ' TI P 120 T90517 .....................$2.90 ,_ - TEA 2000 PALJNTSC ENCODER U10175 .................. $15.00 INS 16550 AFN UART U221 87 ..................$23.95 NEW IC MC34 063 U10416 ................... $2.95 As seen In Silic on Chip's Solar Battery Charger kit. 2 UNI VE RS IAL BRACKETS WITH SC REWS TO MOUNT 3 1/2" HARD DR IVES INTO MOST CO MPUTER CASES X19971 ...................$9.95 Why waste your precious time & money trying to get a quality print out from a "recharged" cartridge when you can buy a brand new Canon Laser cartridge from Rod Irving for only $199.00 EP CARTRIDGE FOR SIDE LOADING PRINTERS C21107..............$199 .00 EP•L CARTIDGE FOR FRONT LOAD ING PRINTERS C21109 ............... $199.00 EP-S CARTRIDGE FOR TOP LOADING PRINTERS C21108 ............... $199.00 BJ CARTRIDGE BC-01 CANON BJ CARTRIDGE BC-01 FOR BUBBLE JET PR INTERS C22218 .............. ......... $ 55.00 RADIAL FIN HEATSINKS TURNTABLE ·· REPLACEMENT BELTS -~-d~ ;,j TB5.DIA.185mm WIDTH 5mm LENGTH 581 mm A17006 .................... $4.95 TB10.DIA.189mm WIDTHSmm LENGTH 593mm A17007.................... $4.95 TB15.DIA.195mm WIDTHSmm LENGTH 612mm A 17008 .................... $4.95 TB20.DIA.205mm WIDTH 5mm LENGTH 644mm A17009 .................... $4.95 TB5.DIA.185mm WIDTHSmm LENGTH 581mm A17006 .................... $4 .95 TB25.DIA.210mm WIDTH 5mm LENGTH 659mm A17010.................... $4.95 BUDGET SOLDERING IRONS ~ Rating 1' C/Watt 150mm Length Des igned by Rod Irving, SCREWDRIVER TIP SOLDERING IRON , 240V • 30mm length H 1o52 o......................... $s. 9 o • 75mm length , 15 WATT T12907 $16 95 ........ ................ · H10 52 5 ......................... $7 .9 o PO INTED TIP SOLDERING IRON , 240V , 15 WATT T 12905 WAS ~ THIS MONTH 0NLv.:·s12.95 DIRECT IMPORT PRODUCT! YOU SAVEi DOU BLE P10538 ............... ......... $6.95 Th e11 are good quality SIMM Socket ■ w ith metal cllpe at th1 enda and not t h e p laetlc on11 which • 100mm leng th H10529 ......................... $8.90 • 140mm length H10534 ....................... $11 .50 • 150mm length H10535 ....................... $ 12· 95 brHk, • 170mm length H10538 ....................... $14.95 MAIL ORDER ·HOTLINE: 008 33 5757 FAX HOTLINE, (03) 543 264B These pin!- are not gold plated so they are much cheaper.Thay are su itable for wire wrapping and flt holes of 1mm (0.04In) diameter. Two types are available Sing le-sided and Double-sided 0 LAMPS & GLOBES Our range of lamps and globes have colour coded wires to denote what voltage they are rated at: Red wires: White wires: Blue wires : 6 volt rating. 12 volt rating. 24 volt rating. CLEAR SUBMINIATURE GLOBES DOUBLE SIDED Packet of 20 H11680 .......................... $3.95 Packet of 100 H11681 ....................... .$18.95 Packet of 500 """'·· ~ "-" Anodized B lack Thermal ~· £:: " WIRE WRAP PINS SINGLE SIDED Packet of 20 H11690 .... ...................... $3.50 Packet of 100 H11691 ........................ $17.95 Packet of 500 H11692........................ $79.95 ARLEC DIGITAL SCALES . S14000............... 6V/80MA..... $0.80 S14001 ............. 12V/85MA..... $1.25 S14002. ............ 24V/50MA..... $1.25 • Dimentions: 6.3mm (L) x 3.2mm(Dia) • All have 120mm wire leads CLEAR SUBMINIATURE GLOBES S14003. ............. 8V/80MA ...... $1.25 S14004............. 12V/85MA..... $1 .25 S14005............. 24Vi50MA ..... $1.25 • Dilnenliona: 10mm (L) x 5.1mm (Dia) • All have 120mm wire leads <C:Qtiiw~ ROUND GLOBE • BAYONET BASE S14006......... 12V/50mA ....... $0.95 • Dlmentiona: 23mm (L) x 11mm (Ola) • Clear glaae lena. ~~~ ROUND GLOBE, SCREW BASE ELECTRONIC K ITCHEN SCA LES • Si mply converts grams to ou nces and ounces to grams by switching the selector key. • Various Items can be individually we ighed in Iha same container using the reset key. , minimum we ight 1g 0.1oz, up to a max . 200 0g or 4.5Ibs , Easy-to-read digital displa. , Compact size enables easy storage. , 12 months guarantee. A15075 .............. $69.95 DIL INLINE BRIDGE = ,¥;, ■ IQjJ ■lllloil .· --===....., KBL06 1·9 10+ 6 AMP S00V.... $3.95 $3 .50 Service per1on1I You need to keep I few of lheae in your part■ box. ~ C3153 5 AMP TWIN DIODES .. $9.95 S14007.......6Vi100mA ..........$0.95 S14008....... 12V/105mA ........ $0.95 • Dimentions: 23mm (L) x 11mm (Dia) • Clear glasa lens GLOBE· T1 FLANGE S14009........... 6V/60mA ....... $1.95 • DI mentions: 9mm (L) x 4mm (Dia) Clear glasa lens GLOBE· T1 BI PIN S14010......... 6V/60mA .........$1 .95 S14011 ......... 12V/60mA....... $1.95 • Dimensions: 9mm (L) x 4mm (Dia) • Clear glasa lens ~11 1111111 'ff""'W ~~ ~ -· SUBM INIATURE GLOBES• SCREW $14012. ......... 6 Voll .......... $0. 95 $14013. ........ 12 Volt ........ $0.95 $14014 .......... 24 Voll ........ $0.95 • Dlmenslona: 20mm (L) x 6mm (Dia)• Designed for use with (I L2) holder• Clear glaH lens. ROD IRVING ELECTRONICS Pty. Ltd. ACN .005 428 437 HEAD OFFICE: 58 RENVER RD, CLAYTON. PH: (03) 543 2188. FAX (03) 543 2848. CITY 48 A'BECKETT ST. MELBOURNE. PH. (03) 883 8151 / (03) 839 1840. FAX: (03) 839 1841. OAKLEIGH: 240C HUNTINGOALE RD, OAKLEIGH. PH: (03) 582 8939. FAX: (03) 582 8940. NORTHCOTE 425 HIGH ST. NORTHCOTE, PH.(03) 489 8888. FAX: (03) 489 8131. SYDNEY:74 PARRAMATTA RD, STANMORE. PH: (02) 519 3134. or (02) 585 1458. FAX: (02) 518 5024. DEALERS: BLUESTAR COMPUTERS : (COMPUTER PRODUCTS ONLY) 271 MAROONDAH HWY. RINGWOOD. PH : (03) 870 1800. FAX: (03) 879 3027. APEN!NQ 01b QF APRIL: BLUESTAR COMPUTERS CONCORD. (COMPUTER PRODUCTS ONLY) GROUND FLOOR 115•117 PARRAMATTA RO, CONCORD. PH: (02) 744 5528. FAX: (02) 744 5405. ~I== ~I== QUALITY 3mm LEDS 1·9 10-99 100+ ""'" ~ ...~ ... BNC PANEL SOCKET 1·9 10+ 100+ P1 0 516 $2.50 $2.25 $1.50 ,, BNC CRIMP PLUG 1-9 10-99 100+ P10530 $3.95 .,3.75 $3.00 ~ BNC SOLDER LESS TWIST ON PLUG 1·9 10-99 100+ P10531 $3.50 $3.25 $3.00 CANNON PLUGS AND SOCKETS 1-9 Z10140(R) $0.15 Z10141(G) .. $0.20 Z10143(Y) .. $0.20 Z10145(0) .. $0.20 1 0-99 100+ $0.12 $0.18 $0.18 S0.18 $0.10 S0.15 $0.15 $0.15 QUALITY 5mm LEDS Z10150(R). $0.15 S0.12 S0.10 Z10151(G). $0.25 $0.20 $0.18 Z10152(Y) .. $0.25 $0.20 $0.18 ROD IRVING ELECTRONICS HAVE THEIR NEW 116 PAGE 1992 MAIL ORDER CATALOGUE OUT NOW! PICK UP YOUR FREE COPY AT ANY OF OUR STORES! ------- FLASHING LEDS RED 5mm 1-9 10+ Z10159 $1. 10 $1.00 MOSFET SPECIALS 1111== 1-9 10+ 100+ 20e 15e 12e 20e 15e 12e 20e 15e 12e 2oe 15e 12e CIC SOCKETS ) ULTRASONIC TRANDUCERS Designed to transmit at 40kHz (L 19990) & recieve at 40kHz (L 19991) withup to 20V IIP on the transmitter. These units can't be heard so are ideal for TV remote controls, water level CANNON TYPE 3 PIN CHASSIS MALE 1·9 10-99 100+ P10962 $3.50 $2.95 $2.50 - ft) CANNON TYPE 3 PIN LINE FEMALE 1·9 10-!lll 100+ P10964 $3.95 $3.50 $2.90 5 CANNON TYPE 3 PIN CHASSIS FEMALE 1-9 10-98 100+ P10966 $4.95 $4.50 $3.50 dectectors, burglar alarms, motion dectectors & information carriers as they can be either pulsed or used in a WIRE WRAP IC SOCKETS These quality 3 level wire wrap sockets are tin p lated phosphor bronze. P10579 Spin $1.50 P10580 14pin $1 .85 P10585 16pih $1 .95 P10587 18pin $1.95 P10590 20pin $2.95 P10592 22pin $2.95 P10594 24pin $3.95 P10596 28pin $3.95 P10598 40pin $4.95 $1.40 $1.70 $1.80 $1.80 $2.75 $2.70 $3.50 $3.50 $4.50 COMPUTER CABLES • Six conductor ■ hI8'ded computer lnh,rlace cable. W12670 • CIC6 6 con. 1OM+ 100M+ $1 .30M $1.10M $1.00M W12672 • CIC9 9 con. 1OM+ WIRE WRAP IC SOCKETS Th••• qualtty 3 level wire wrap sockets are tin plated phosphor bronze. P10579 Spin $1.50 $1.40 P10580 14pin $1.85 $1. 70 P10585 16pin $1.95 $1.80 P1058718pin $1.95 $1.80 P10590 20pin $2.95 $2.75 P10592 22pin $2.95 $2.70 P10594 24pin $3.95 $3.50 P10596 28pin $3.95 $3.50 P10598 40pin $4.95 $4.50 1O0M+ 1OM+ 10M+ 1OOM+ 10M+ 100M+ $3.90M $3.40M $3.00M ELECTRET MIC INSERTS With pln ■ for euy board Insertion. C1O17O 1().99 100+ 1-9 $1.20 1-9 $9.50 $10.00 $8.50 $9.50 10+ $8.00 $9.50 $8.00 $8.90 C NICADS TOGGLE SWITCHES ) ~ Save a fortune on expensive throw away batteries with these qualily Nicads and Rechargeral ECONOMY TRANSFORMER L19991 ....... $2.95 Size AA 450mAH 1-9 10+ 100+ $2.95 $2. 75 $2.50 SlzeC 12AH $9.95 IDC PLUGS . & SOCKETS WOW! FROM $1 .00 $9.50 $8.95 SlzeD 12AH $9.95 1·9 10+ 2'155 240V 6-15V 1A M12'155 ......... $8.95 $7.95 2'156 240V 6-15V A2 M12'156 ........ $13.95 $12.95 $9.50 $8.95 PS2 CONNECTORS Cc.-J 2851 240V 12-6V CT 250mA M12851 ......... $4.95 .. $4.50 $1 .00 $0.90 100+ • OE9P P12166 $1.50 $1.20 $1.00 • DA15P 15pln plug P12168 $1.50 $1.20 $1.00 • O825P 25 pin plug •• P1217D $4.50 $3.95 $3.50 DTYPE IDCSOCKETS 1-9 10+ • DESS 9 pin eocket 100+ P12167 $1.50 $1.20 $1.00 P12169 $1.50 $1'.20 $1.00 • D825S 15 pin eocket -- P12171 $4.50 $3.95 $3.50 1O0M+ $3.SOM $3.20M $2.50M W12678 • CIC25 25 con. 1-BM Receiver • OA1SS 15 pin eocket $2.50M $2.20M $1.90M W12676 • CIC16 16 con. 1-9M Transmitter 1-9 10+ L19990 ....... $2.95 $1.95 1-9 10+ 9pln plug $1.60M $1.50M $1 .20M W12674 • CIC12 12 con. 1-9M continuous wave mode. D TYPE IDC PLUGS CANNON TYPE 3 PIN LINE MALE 1-9 M DB25 CONNECTOR SPECIALS 1·9 10+ P10880 DE9P $1.00 $0.80 P10885 DE9S $1.00 $0. 70 P108111 DA15S $1.00 $0.70 P10892 DA15C $1 .00 $0.90 P10895 DA15S $1 .00 $0.80 P10902 DB25C $1.00 $0.80 P10904 DB25P $1.00 $0.80 P10905 DB25S $1.00 $0.80 2SJ49 2SJ56 2SK134 2SK176 • 114" NUT DRIVER • 3116" NUT DRIVER • 3 CLAW PARTS RETRIVERIEXTRACTOR • TWEEZERS , T10, T15 TORQUE SCREWDRIVER • #1 PHILLIPS SCREWDRIVER , 3116" FLAT SCREWDRIVER • IC EXTRACTOR • IC INSERTER, 14-16 PIN 1c·a • #0 PHILLIPS SCREWDRIVER , 118" FLAT SCREWDRIVER • VINYL ZlPPER CASE Tuneable:92-104MHz Freq response: 5015kHz. Range: over 300 feet in open field. A10450 .......... $24.95 6672 240V 15 30vc 1A tapped C 1-9M ~ RECTANGULAR LEDS RED GREEN YELLOW ORANGE We have a great range of panel meters at great prices! 010500 MU45 0-lmA $9.95 010502 MU45 50/50UA $9.95 010504 MU45 0·100uA $9.95 010533 MU52E O·SUA $12.95 010538 MU65 0•50uA $12.95 010540 MU65 0-1mA $12.95 010550 MU650-100UA$12.95 010560 MU650-20V $12.95 VOLTAGE REGULATORS BARGAINS Deecrlptlon 7805UC 7812UC 7815UC 7905UC 7912UC 7915UC 78L05 78L 12 LM324 555 741 1-9 10+ $0.50 $0.50 $0.50 $0.60 $0.60 $0.60 $0.40 $0.40 $1.00 $0.40 $0.50 $1J.45 $0.45 $0.45 $0.55 $0.55 $0.55 $0.30 $0.30 $0.90 $0.38 $0.45 IDC CENTRONICS 36 WAY PLUG & SOCKET 1-9 10+ • Plug P12200 $3.95 $3.00 • Socket Pl 2201 $3.95 $3.00 M166n ........ $12.95 $11 .95 VCA MONTOR ADAPTOR oe.sP FEMALE TO 12V DC FANS 80 X 80 X 25.4mm 12V DC. 1.7 Watt 0.14 Amp T12469................$18.95 10+ fans, only $17.95 FANS Quality fans for usa In power amps, comput1r hotspot cooling etc. Anywhere you need plonly of air. 240V 4 5/8" 115V 4 5/8.. T12461 ..$16.95 T12463 .. $16.95 240V 31/2" T12465 .. $16.95 115V 31/2'• T12467 .. $16.95 10+ fane (mixed) Only $14.95. NEW SWITCH BOXES 100+ $2.95 $2.95 9 PIN D SWITCH BOXES 2 WAY.•• - ........... $59.95 4 WAY................ $69.95 MONITOR & KEYBOARD SWITCH BOXES only $69.50 HD-15P MALE .X15670 .......................... $14.95 fijJ MOUSE ADAPTOR DB·9PMINI DIN 9P PLUG X15672 ........................... $14.95 HEATSINK COMPOUND ~ Heatsink compound is applied 10 the base and mounting studs of 1ransistora & diodes. It maintains a positive heataink seal that Improves heat transfer from the device to the heatsink, thus Increasing overall efficiency. H11800 .. 10g..• $2.00 H11810.150g. $29.95 Computing On The Big Screen Forget about CAD & desktop publishing on a small screen. To really work with these programs, you need a large-screen, high-resolution monitor. By JIM SHARPLES* The recent popularity of others , such as desktop pubGUis (Graphical User Interlishing, CAD and graphics, faces) and WYSIWYG (What larger screens are almost a You See Is What You Get) necessity. If you try doing a has resulted in a marked 2-page layout in PageMaker decrease in the prices of or Ventura, for example, the monitors, particularly the resulting display is practicolour models. cally unusable. Or what The advent of Windows about trying to design a 3.0 in the IBM PC compatlarge double-sided board on a small screen. It is possiible market has created a ble but not the most effihuge demand for colour cient way. monitors capable of dis playing higher resolutions Colour or mono? than ordinary VGA. These higher resolutions are reEighteen months ago the ferred to as "Super VGA" price gap between colour and can not only display and monochrome monitors the 640 x 480 pixel resoluwas fairly substantial and tion of standard VGA , but if the application didn't abThe Philips 4CM2799 20-inch colour monitor supports also 800 x 600 and 1024 x solutely require colour, then resolutions up to 1280 x 1024 & can be used with a wide 768 resolutions. Many of monochrome was certainly range of video driver cards. the larger monitors also supthe most economical purchase. Now, however, the port 1280 x 1024 but there there is a corresponding demand for are not (yet) many video cards able to price gap has narrowed to the point larger monitors. It's very nice having where monochrome would not be a display at this resolution. a 14-inch monitor displaying Win- wise choice, particularly as many Most of the recent monitors are the "multisync" type; ie, they synchro- dows or CAD (Computer Aided De- newer programs rely on colour to make sign) in 1024 x 768 resolution but nise at multiple frequencies. This them easier to use. Menus, grids, tools, everything is so small! Just try using a icons, selection areas and many asmeans that IBM compatible users 14-inch monitor, swap to a large moniaren't the only ones to score - Mac, pects of the programs use colour to tor for a week or so, then return to the Amiga and other computers can use make the user's job more instinctive 14-inch monitor. You'll really miss and obvious. the same monitors. that large screen. Windows 3.0 is a good example. Larger monitors For some applications, the smaller Whereas Windows 2.0 hardly needed size is not much of a problem but for With the increase in resolution, colour and indeed, it was just a 1uxury, 16 SILICON CHIP Windows 3.0 was designed to use colour. In fact, it is somewhat difficult to use quite a few applications in monochrome! CAD is another software category where colour is almost essential, particularly with multi-layered applications such as circuit board design. Drawings quickly become confusing and hard on one's concentration. But what about the difference in quality between monochrome and colour? Let's face it - monochrome will beat colour hands down in a contest where resolution is the same. It's much easier having one electron gun than trying to align three at once. Again, things are changing. The resolution of colour monitors is improving all the time, to the point where it doesn't really make that much of a practical difference, and in any case the advantages of colour outweigh the clarity of monochrome. How large? OK. We've decided on a large colour monitor. What is the best size to go for? Well, here's where personal taste steps in. In my view, a 17-inch monitor is ideal for the broadest range of applications, whether they be textbased (eg, wordprocessing or database under MS-DOS) or graphicsbased as in Microsoft Windows. Text- based applications can be rather overpowering when viewed on a 21-inch monitor, unless you happen to be very short-sighted, in which case they are a great idea. I know of one person who bought a 20-inch monitor for this very purpose. (By the way, notice how we still persist in measuring monitor diagonal sizes in inches? Obviously, this is the strong influence from the American computer industry). 17-inch monitors As mentioned, this is the best general purpose monitor size. They have the added advantage of taking up a little less space on the desktop, though even a 17-inch monitor seems huge after a standard 14-inch one. There haven't been many of this size monitor around until a recent flurry of announcements by various manufacturers. It seems they all suddenly realised that this would be the logical choice for many users and announcements have been appearing hard on the heels of one another. Another curiosity is that they have appeared with almost the same specifications: flat screen, 1280 x 1024 maximum resolution, 0.26mm dot pitch and very similar horizontal and vertical scan rates and bandwidth. These specs are pretty good for this A video glossary Autosizing: this is the ability of the monitor to maintain a constant image size across different video modes. For example, this is important when entering Windows in 1024 x 768 non-interlaced mode from the normal DOS VGA mode. If this is not available, either automatically or as a user-programmable option, then the user must change the size and position of the image every time another mode is entered. Dot Pitch: the distance between the holes in the shadow mask in a colour monitor. The shadow mask (which sits behind the screen) ensures that each electron beam (from the red, green and blue guns in the tube's neck) hits the correct dot in each triad of red, green and blue phosphors. The smaller the dot pitch, the finer the grain of the image. Horizontal Frequency: how often the monitor scans a horizontal line, measured in kHz. VGA is standardised at 31.SkHz, while Super VGA varies depending on the vertical refresh rate of the graphics adaptor. Multisync: a term originated by NEC to indicate that the monitor can synchronise to any horizontal line frequency within a given range. Some cheaper monitors are actually "multiple fixed frequency" which means that they synchronise to particular modes, usually VGA 800 x 600 and 1024 x 768. Pixel: the smallest triad or group of triads, depending on the resolution selected. Triad: a triad comprises three phosphor dots - red, green and blue arranged in a triangle. Each of the three electron guns is assigned a particular colour and that gun excites only its own phosphor dot in the triad. The combination of excited dots determines pixel colour. Vertical Frequency or Refresh Rate: how often the monitor scans a compete screen, measured in Hz (cycles per second). The higher the refresh rate, the less flicker is noticeable. Standard VGA has a vertical frequency of 60 or 70Hz, while Super VGA should be an absolute minimum of 56Hz but preferably 70Hz or higher. This 19-inch high-resolution monochrome monitor from Radius is ideal for desktop publishing & graphics design. It is fully VGA compatible & can be used with either PC or Macintosh systems. Video Bandwidth: the highest video input frequency the monitor can accept, measured in MHz. This determines the maximum resolution . MAY 1992 17 size of monitor and should make them a popular choice. benefit from a larger view of all those figures . 19 & 21-inch monitors Portrait & 'full page' monitors These are the big ones, needing plenty of desk space. Don't try to use them on a narrow desk - you'll land up with the keyboard in your lap! And do a weightlifting course before moving the monsters. They are definitely in the heavyweight class. Once in place however, the view is worth it. Both graphics and text are easier to see and manipulate, reducing the need to zoom in on working details. There is a corresponding saving in screen redraw time between the zoom levels. Monitors in this class usually have a 0.31mm dot pitch, which is quite acceptable, though some go as low as 0.28mm: This is the ideal monitor size for those working almost exclusively in high-resolution graphics mode, whether it be CAD, desktop publishing, animation or even large spreadsheets. Maybe accountants could also What is a 'full page' monitor? A number of times I have been asked to recommend a monitor to fit this vague notion and when pressed to clarify the request, the customer usually answers: "a monitor that displays an A4 page". My answer is almost always in the form of another question: "What size would you like your A4 page to be?". The person wanting a full page monitor usually needs it for a desktop publishing application and I have to point out that even a 12-inch monitor can display a full A4 page. But if they want it displayed full size, the options are limited and are pretty expensive. I also point out that unless they are working solely on publications where only a single page view is necessary, the portrait or 'full page' monitor can be a liability when viewing two pages fllc Edit l2plloni ,eage Iypc Elemcnl Window Help J Computirig'On •I The l3ig Screen Forget about t,AD & desktop publisll.Ufg on a small screen. ToreaD~ work ~ilhthesep~og,JpDl~,youneeda large-screenh,gh-resolution "f°:nil'or. ~:,- JIM SHARPLES ' These two captured screen images from PageMaker show how much more information is displayed at higher resolutions. At top left is a 1280 x 1024 display, while at bottom right is a 640 x 480 (standard VGA) screen capture. The text is directly readable on-screen in the highresolution mode but has "Greeked" in the low-resolution mode. 18 SILICON CHIP side-by-side, or using other applications. The only exception to my prejudice against portrait monitors is a rather curious animal - the Radius Full Page Pivot monitor. This colour monitor acts as its name suggests - it pivots between portrait and landscape modes, using software drivers to change the orientation when the monitor is pivoted. Portrait mode can only be used in applications for which a driver exists and these include some CAD, wordprocessing and spreadsheet programs, plus Microsoft Windows. A Mac version is also available. The Pivot measures 15-inches diagonally, so it does not really fit into the "large monitor" category. VESA & Swedish standards The Video Electronics Standards Association has defined standards for Super VGA signals to reduce flicker. This can be particularly noticeable when the screen background is white, as in Microsoft Windows. The official standard requires the vertical refresh rate to be 72Hz at 800 x 600 resolution and 60Hz at 1024 x 768 resolution. Both monitors and video boards must be able to conform to or exceed these standards. Sweden's National Board for Measurement and Testing (MPR) has pub- A 17-inch colour monitor is a good compromise between size & cost for many applications. The multi-sync CMl 7MBD from Tatung features 0.26mm dot pitch, 1280 x 1024 resolution (max.), a flat dark-tinted CRT & a microprocessor-based control system for automatic screen configuration. It can be used with a wide range of driver cards for both PC & Macll computers. lished standards for monitor emissions, designed to reduce health risks and eye stress. Many manufacturers are designing monitors to conform to the standards, though there is still some controversy over the supposed health risks. Video graphics boards When discussing high resolution monitors, one part of the equation that cannot be left out is the board generating the screen graphics, and here I will restrict discussion to PC compatibles. A series of simple calculations will show these results: Resolution 640 x 480 (VGA) 800 X 600 1024 X 768 Pixels 307,200 480,000 789,504 It is obvious that at the common high resolution of 1024 x 768 the number of pixels is over three-quarters of a million! And the poor graphics board has to frequently redraw most of them! Standard VGA has a limit of 16 colours, whereas high resolution boards can usually generate 256 colours. This means that the high resolution board is manipulating five times as much information as VGA. The question of which graphics board to use is therefore an important one if you want your screen updates to happen at an acceptable pace. Basically there are two types of high-resolution boards: those with graphics coprocessors and those without. The most popular and possibly fastest of the boards without coprocessors are those based on the Tseng Labs ET 4000 chipset. Apart from Tseng Labs themselves, quite a number of manufacturers produce boards using this chipset. A better option for those using large monitors at high resolutions are the coprocessor based boards. IBM ini- The Radius Pivot Display System is a colour monitor that pivots between portrait & landscape modes to suit your application. Versions are available to suit both the PC & the Macintosh family. tially produced the 8514/A coprocessor for 1024 x 768 interlaced resolution and others have subsequently cloned this chip, adding extended features like 1024 x 768 non-interlaced and higher scanning frequencies (see glossary for an explanation of some of the terrris). Another popular coprocessor is the Texas Instruments TMS34010 and TMS34020, and boards designed around these chips can respond to TIGA, the Texas Instruments Graphics Architecture software interface. In terms of speed, there is not much to choose between the 8514/ A and MAY 1992 19 There are also some lower-cost boards appearing which contain the Sierra DAC (Digital-to-Analog Converter), which is 15-bit and generates 32,768 colours, and then there are other 16-bit adapters such as IBM's XGA which generate 65,536 colours. For most purposes, a 256-colour board based on the S3 chip would be my choice, both in terms of speed and economy. What should you look for? Hitachi's Model CM2187 is a 21-inch multi-sync colour monitor with a 0.31mm dot pitch & a resolution ofup to 1600 x 1200 (non-interlaced). It is compatible with a wide range of graphics standards & features microprocessor control. TMS340x0, though the 8514/A-based boards tend to be a little cheaper. A new contender is the 86C911 chip produced by S3 Inc. The boards based on the S3 are particularly exciting, not only because of their fast speed, but because they cost about half the price of the other two types. Most graphics boards available gen- erate 16 and/or 256 colours (4 and 8 bits per pixel), though there are other more expensive boards available which can generate 16.8 million colours (24 bits per pixel). These boards would only entice the most demanding users who need photographic-like images and can afford the thousands of dollars required to purchase them. 16-inch Colour Display for the Mac Apple's new Macintosh 16-inch Color Display features 832 x 624 resolution & is supported by all current Apple video cards & by the on-board video interface of the Quadra CPUs. Alternatively, users can choose the 8.24 GC card (not needed for Quadras) which offers 32,768 colours & graphics acceleration. 20 SILICON CHIP Dot pitch is important - newer 17inch monitors are 0.26mm, while a 20-inch monitor should be 0.31mm or less. Autosizing is a definite requirement if you will be changing modes and may be either automatic or user-programmable. Colour-correction may be important depending on the type of work you do. The new NEC FG series is one of the few monitors available with this feature built-in. Non-interlacing at higher resolutions can increase viewer comfort but it is important to match graphics card capabilities to that of the monitor. Finally, spend a reasonable amount of time looking for the monitor you need and don't skimp on price and quality - you will spend long periods looking at the screen. SC •Jim Sharples runs Computrack, a company that supplies PC-based desktop publishing equipment. Phone (02) 451 2521. Only $129 Order Your Copy Today 00 RINGTODAYFOR.,A • FREE DEMO,Ol'SK "Having 1st ACT! is like having your own personal, assistant that thinks and works just like you." . Features pull-down menus and pop-up windows so you can complete tasks with only a couple ofkeystrokes. Built in WordProcessor allows you to write to your contacts quickly and easily. Time scheduler allows you to keep track of important dates for calls, meetings and to-do's. Keeps details of your contact.s at your' fingertips. Instantly displays the entire contacts file - addresses, phone numbers, notes you've written, as well as completed and future activities, even personal details. Do you have a computer? Have to keep track of more than 100 names and addresses? Then you need JstACT!. Manages and Tracks your Contacts Over 50,000 copies already sold in the USA 1st ACT! - The World's leading contact Manager Options: UB1 o case with front & rear panels . Front Panel is punched and screened, rear is punched. $19.99 Approved Plug Pak $17.95 Kit $135.00 • Voice reco rding and reproducing LSI using an ADM algorithm. • Capable of recording and reproducing up to a maximum of 16 phrases . • 4 different bit rates can be selected. (BK, 16K, 22K, 32K bps).• Pausing function . • Beep sound output.• Mute Circuit. • Built-i n DRAM refresh circuit.• Built-in band pass filter. • Builtin microphone amplifier. • Built-in 10 bit DAC. • Built-in DAC output buffer. • Uses a 640K resonator. • +5V single power. • Clocked CMOS for low power consumption.• Variabledebouncing time for start, stop and pause by the CPU terminal. Features: The CMOS chip used in this kit is a surlace mounteq device, and so we have had these premounted to the board. The kit comes complete with a full set of instructions and 1MB of RAM. Prefitted CMOS Surface mount Chip The CMOS LS I chip used for this project uses a minimum of power. Reco rd ing and reproduction of the signals is processed through the CMOS chip us ing an (ADM) Adaptive Dela Modulation algorithm. This provides a clean clear recording. An electret microphone is used, and the CMOS chip has a builtin microphone amplifier as well as a muting ci rcuit. A 57mm speaker is provided to ensure quality reproduction. A 5mm LED is included to show the unit is recording. Low power consumption This digital voice project has hundreds of uses and wil l only take you a couple of hours to build. You can also install up to4M B of RAM for longer recording ti mes. Power is supplied from a low voltage plug pak (optional). A Voice recorder you can build in a afternoon Easy to build Digital Voice Recorder 7J 3 :,q; a.3~ )< , ~ .z g a 5· OJ -0 a. 0 :E ~ 5· 3 0 ;I 0 :(0 "' " a, 0 : (I) <-,, ~ ::::!. a, a, s * !lo c.Q ;i;; e I 'V 0 Q (0 ' " ' FREE Software ~ With each kit you will receive t he QL2 Fax/ Modem software featuring both pull-down menus and mouse support. Value packed kit ■ Each kit has been specially prepared to ensure you are able to build the Comma Fax/Modem with a minimum of specialised skills. We have also weighed each kit to ensure every component is included. There is also a step-bystep guide to testing your Fax/Modem throughout the building process . 00 -,;"io" 00~ ~... (t) 6 ;;;· i:,. (IQ i:,. i:,. e (t) ~o ~-~ ..., po;-~ '"d ...., - CD CD ~ m~ H en en Cl) a. ~ _., ~ _., w (X) (X) ~ "".... gJ ........ Q. !:: ~ ~ m -0 e ~ -~~i 1•11•' SERVICE IS THE DIFFERENCE__ tri - ~ ~ -I ~ SERVICE IS THE DIFFERENCE e SERVICE IS THE DIFFERENCE (t) "' ~ ~- 8 Pi ::, ~ ~ 00 s "' '"d trl l:l "' ;;i ::ti -- . .... i:i. 0 i:,: :,;"ois:'"' ~ <; coe'.p,:ii~;:l'"' 9'"0'"'"'"':="'-1:l '"d i:i. (t) • "' "' z ,o<""'.!" t:! i6§P>.oof/¾-• ~ i:i. ~ "' §'. ~ 0 i:,. ATl'ENTION: FAX/MODEM OWNERS If you own a Comma, Maestro, Interlink or other Fax/Modem and you are using the QL2 Software, then upgrade to the latest Version 2 for only $40.00 including P&P. This new version has a number of new features. Call for a Fact Sheet. Note: This device does not have an Austel permit in force. Connection to Telecom lines is an offence. SERVICE IS THE DIFFERENCE s i !!g_cg~ i s- !!l > §l ge.g, [1!l • -gi "'' Illa, ~ [§ a a. i;i ., a. e,m - (/) -i z ::I : ..:::r,.. ~ s,.,.a , :0, 8:i! "' !. . !D ~ 3 AQ !D = ~ !" I!!. en -n a, en :o ~ "2.;,r -i :E -n ~ cc 01 t.O -00t-:l ~ Ul ~ Pl ~ s- w ., , ~ I z < As well it's also a modem . . . . The Comma Fax/Modem is a fully AT command seri es V compatible modem. Features include V22/V22bis standards (V21/23 is an option) both 1200 and 2400 baud rates are supported as yvell as auto answer, dialing and disconnect. You will find it compatible with all popular communication sen.rices including most bulletin boards. Now Available $99.00 .. ' MNP and V42bis option. V21/23 option. $39.00 0 TRY PC MARKETPLACE SUPERFAST MAILORDER - PHONE OR FAX TODAY! -n:r - 0 :I: ,.. -i! """ c<- :ii oo ::," -- R, z :0 :s::: -0 -0 :!'. .. C 2. !!I ~ ..., i::: ~ ;J . p 11111111, c22 (J)Q o i ~ 91 3 ~ trl - -OQ (t) <" g_ (t) 0 ~ ;;;· s"' ~ ~ .... '< !" a. t"< >~ 8" (t) .., (t) ::r 8 ► ~ cm -ea~-~~ i,.. ., ~t-< ::r~ ;>.!" (t) e. ::if/¾:E lJJ oen 0 ~~ 1\)0 ~g ~g_~3-g. 3i ~:lli~~g"cfil~[8"~ ~S' a ~ 0m Ox z 0, _., 0:0 ~~iil~gg!D CD ~~ !!56":l 8~(t)<>i:i.f;ooO~'"' 0, _., 0 z:o ::S! :0 \.Cu !,~'? :::r:I: sooS,f;e:i:i.s~o~ s;:om -c:s~i! 0 C 3 o-4 r,i:>- " OOr,p, '< g ~ ~ OJ 0 cii 0 :x, :x,"' 0~3.W 'TI CJ) ::, "£ ~ ~ ro en &. ~ e. o. Ul g ~ CD l00's Now Sold Build ~our Own Fax/Modem This is a fully featured kit The Comma Fax/Modem isa commercially designed kit you can build It will turn your PC (or Macintosh) into both a fax machine which can (t) transmit faxes up to 9600 baud, as well as a Modem which supports both U).i 1200 and 2400 baud. "C You get all the necessary components as well as a professional case, and (t) power supply . You also receive FREE Fax/Modem software. All this for less than $300. The Comma Fax/Modem uses the latest technology in digital signal processing to ensure lasting troublefree operation. Send faxes from home The Comma Fax/Modem is a fully featured fax machine similar to units ""I costing over $1000, which will transmit faxes at up to 9600bp. ~ Your faxes can now be sent directly from your PC without having to print Q ....... them first. Programs supported such as Ventura Publisher, Wordperfect, Q' Windows, TIF~' and Dr Halo to name but a few. You can view incoming faxes on-screen or print them using a standard dot matrix printer. Incoming files can also be exported in either TIFF or PCX format for use in most popular graphic packages. ~ Only print the faxes you want to keep - just think of the savings on expensive fax paper. Time saving The Comma Fax/Modem will also receive faxes in background while you continue t o work. When faxing out the Fax/Modem will redial an engaged number so you can (t) be sure your faxes are sent. The software also automatically keeps a complete log of both incoming and outgoing faxes. Also supported are cover pages, broadcast faxes, and scheduling. The software keeps a database type register ofregularly used fax numbers for easy retrieval Ul ~ ~ ~ g. c.o_ ccnc. • I» o'< ;· -c-< .ii. :::::, "TI ::iO gOJX ::. :::::!'. ~£ 5. g~ -g, ~ NO 3 -U) ro ::, -0 0 0 - · (1) ~-.; ::, C CJ) -0 3 0 g0 a. gi Q. :::J e?. o CD -, 0 OJ -co :::J OJ -o~ ~ro s· 0""- 0J~ '< a.~Z :::J O - - -- · 0 "' ;: ~a.~gj5.:E o _ go'< o '< 0 c x o :E o OJ5°0J3 1\) C CJ) C :E 5g g £ ~ £ =--co !ii a. ::, -o ::, 6S "'~ f!!.O::, :::::!'. 0 (/) (D - · § '< c ::i"'-g ~ OJ o -■.: gg~a el gi:::"C 0 en cr- oo - w - :::J D> O (/) - · o 3__ >< o "' a: ::iro IB en -~ CD ~- C CO ~ 5 · CD J> ~~ 6' ~§1jl5g ::::, -g. ~ ~'g !ii~ i} .,, :::c :::c ••••••• :e s: 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. Low cost audio oscillator This low cost oscillator is based on the popular Wien bridge configuration. It is powered by a single +9V supply and draws only 8mA, so it is ideal for portable, battery-powered operation. The frequency can be continuously varied over the range from 16Hz to 244kHz, with the output voltage variable from 10mV to 5V peakto-peak over this entire range. There are four frequency ranges, set by ganged switch Sla and Slb, with the actual frequency being set by the dual gang pot, VR1a and VR1b. The two 4700 resistors in series with VR1 prevent the resistance from becoming too low and stopping oscillation. These components are essential to ensure that the upper frequency limit is as high as possible. VR2 is a presettable trimpot and should be set for maximum output voltage without clipping. You will Bulletin board watchdog This circuit was devised to act as a "watchdog" for a bulletin board (BBS) and to reset the computer should it "hang" for any reason. It connects across the RS-232 line and monitors DTR, TXD and CD (also known as RLSD). An IDC ribbon cable is ideal for this application, as an extra "D" connector is easily added to the line. The inputs are isolated by 100kQ resistors so that line loading is negligible. The 1N914 diodes on the inputs prevent signal levels from going above the +5V supply rail or below 0V. IC1b forms an oscillator which clocks a 4020 12-stage binary counter. Should the count reach a predetermined level without being reset, Q1 will be turned on, firing the 555 monostable which in turn op- 22 SILICON CHIP VR1a 10k VR1b 10k 470n 4700 S1b S1a 0.1 0.1 o--1 .01 o-1 t--o ~ +9V +9V t--o 470lc VR3 47k ♦ 470k .001 o--1 .001 470k +9V .01 4. 7 4.7+ + .- 47k VR2 47k 56011 OUTPUT •PJ¼ 0 D1 D2 211N914 need to check the setting over each frequency range to find the best compromise. The output is fed via VR3 which acts as a level control. before being erates Q2 and relay RLY1 which resets the computer. Setting the 10kQ trimpot for a clock frequency of 1Hz allows time delays of up to 34 minutes to be obtained, plenty long enough for this application. With the computer off-line, say for maintenance purposes, the DTR lead is low and gate IC1d will be high, holding the counter chip reset. When on-line, DTR goes high and pin 11 of IC1 falls low, allowing the counter to clock. Should the computer transmit data, the TXD lead will pulse high, to be inverted by IC1c, and cause IC1d to reset the counter. Thus, while on-line with the computer sending data, the watchdog circuit is continually being reset. Should the computer hang, there will be no activity on the TXD line and when the counter reaches an buffered via emitter follower Q1 which provides a nominal source impedance of 600Q. Steven Merrifield, Newlyn, Vic. ($25) appropriate count, the computer will be reset. The CD/RLSD lead allows for the counter to be paused whenever the modem is communicating with another. This facility was not provided in the prototype but found to be necessary, as the BBS which it was monitoring did not send acknowledge characters when receiving large mail packets. When waiting f9r a call, the BBS regularly sends a reset string to the modern, which serves to reset the watchdog and thus prevents the system from being unnecessarily reset. This usually happens every 10-15 minutes, so a "watchdog time" of 17 minutes (Q11 with 1Hz clock) was chosen. The Q12 output of the 4020 (pin 1) will give a watchdog time of 34 minutes. Greig Sheridan, Ashfield, NSW. ($30) Airconditioning override with kickdown switch Most 4-cylinder cars with automatic transmission lack power when accelerating or overtaking with the airconditioning on. This automatic cutout is controlled by the switch under the accelerator that controls the kickdown solenoid. The kickdown switch is used to control a relay which is placed in parallel with the existing kickdown solenoid. The relay contacts are then wired in series with the electromagnetic clutch on the airconditioning Nicad fast charger timer +12V These wires are connected to the "normally ACCELERATOR closed" contacts on the KICK·OOWN SWITCH TOAIR relay, so the airconCONDITIONER --+--------CONTROL ditioner runs normally RELAYS /,,/ during normal engine KICK•OOWN AIR CONDITIONER demands, but when the RLY1 SOLENOID CLUTCH I ELECTROMAGNETIC transmission changes down under acceleration, the compressor is temporarily cut out. The compressor. Most cars have some sort fan in the cabin continues to run, so of connector harness to the clutch, so you should not notice that the comit should not be necessary to cut the pressor has cut out temporarily. clutch wires - just put connectors on Peter Bradstock, the wires which run from the relay. Epping, NSW. ($20) 11 10 +13.B V O - - - - - - - ~ - - - - - - - - - - - - + - - - - - - - - - - - + - - - - , 16 This timer circuit is used in conjunction with a resistance lead for fast charging 7.2V 1200mA.h nicad racing packs from a 12V car battery. It normally takes 15 minutes to charge a battery from flat but if you then forget to disconnect it, the battery will be damaged. Mechanical timers. can overcome this problem but they can jam and the result is still a ruined racing pack. The circuit is simply a 555 timer (ICl) which clocks a 4020 timer (IC2) 256 times over a period of about 15 01 8C337 10 IC1 555 RESISTANCE LEAD WI• minutes. It then switches Ql and RLYl off. VRl is adjusted to give the required period. The+ 13.8V supply rail PACK LED1' .,. i- is derived from the car battery. Paul Fitzgerald, Te Aroha, NZ. ($20) 25-PIN D CONNECTOR CD/RLSD 8 i 4093 07 1N4002 270k 16 lO CLK IC3 -555 VR1 10k +5V + 0+ TO NICAD IC2 4020 LED1 10:r D3 1N914 -:- ,ol ''' + I ,+5V RL1 71 IN PARALLEL .,. WITH COMPUTER RESET SWITCH .,. 100kl TXD 2 11 11 RESET .,. ~ +5V LED2 D5 1N914• D8 1N4002 100k OUT DTR 20 FROM PLUGPACK 06 1N914 +5V 1i OV ~ T GN077- MAY1992 23 BY PAUL LYNCH The PC game is changing again: OS/2 is really here PC users find themselves in an unusual position in 1992: IBM is really after our dollars. The year is still young but it is difficult to imagine that much will happen that's more important than the new release of the IBM operating system, OS/2. IBM released version 2.0 of the system at the end of March. It's a true 32bit system, which means that it runs extremely quickly. MS-DOS and PC-DOS run at eight bits in real mode - and Microsoft Windows at best runs in only 16 bits in 386-enhanced mode. As many users have found, this higher mode of Windows is effectively no faster than the usual protected mode. OS/2 also tackles memory management in innovative ways that make have a machine with a 40Mb hard disc, it's quite likely that OS/2 is not for you - at this time. What we have now is software that in effect will prescribe your hardware configuration - if you choose to accept it. What IBM has done to encourage you to do this is really quite remarkable. The nature of SILICON CHIP is pretty obvious - it's a technical magazine. But at some stage, the PC user looking for software must recognise the corn- "To run 05/2 version 2.0, you will need at least an 80386SX central processing unit (CPU) chip. You'll also need a lot of spare storage. The minimum requirement is 15 megabytes" previous systems quite obsolete. All this is good - in fact, excellentnews. But part of the news is not quite so good. To run OS/2 version 2.0, you will need at least an 80386SX central processing unit (CPU) chip. You'll also need a lot of spare storage. The minimum requirement is 15 megabytes. If you install the lot, it will occupy 30Mb of your hard disc. So if you already 24 SILICON CHIP mercial environment in which he or she is operating. There are many dead ends in the history of the PC: I have a number of software packages on my shelves that I seldom used some years ago and will never use again. They've been a waste of money - quite a lot of it, I'm sorry to say. They remind me daily of the importance of looking beyond the technical parameters when buying major software and equipment. The new version of OS/2 is quite wonderful but a straight technical statement of its characteristics will not answer the sensible questions of most users. After all, to run it, many people must consider replacing their present computer at a cost of some thousands of dollars. Is this a good idea? Answering the question calls for a quick stroll through the marketplace. The race for our dollar Quite a lot of the stuff laid out in the market is there not because it's ready, but just to beat a competitor in the race for our dollar. Central Point Software and Symantec had just such a race last year Central Point was in a hurry to put PC Tools 7.0 on the market, because Symantec was in a hurry to present Norton Utilities 6.0. Haste overcame caution and within weeks of each other, both manufacturers found it appropriate to bring out free updates designed to fix the errors that existed in the products as first marketed. Central Point issued PC Tools 7.1 and Symantec offered 6.01. The feelings of people who purchased the bug-infested versions only weeks or months earlier have not been recorded publicly. But in a recent article in the American magazine PC Computing, senior officials of WordPerfect were quite frank about the error they'd made in putting their version 5.0 on the market too soon a few years ago. As they see it now, the product had so many glitches that it almost destroyed their reputation. (It's worth recalling that it's only in the past few months that WordPerfect re- leased its Windows version - two years behind its major competitors). Beyond this urge to hit the market at the earliest possible date, all software manufacturers find themselves to a large extent in the fortune-telling business. What do we users want? What will we pay for? How much of what we want should be in the final package? WordStar users saw what started out as a single double-density disc program wind up, in version 5.5 , as one that needed 19 discs for the same program with all kinds of bells and whistles. I doubt that any single user wanted, or applied, all the wonderful things offered on those 19 discs but the manufacturer had a commercial need to supply the lot. Since 1990, software manufacturers have had another question to answer: when they move beyond MSDOS, should they develop a Windows version or an OS/2 version? OS/2 was clearly a technically superior interface ·but market realities are such that many of those software designers who decided that OS/2 was the way to go got their fingers burned quite badly. While OS/2 had been round since 1987 as a joint effort between Microsoft and IBM, there was a rupture of the partnership. Microsoft pulled out because of the staggering success , starting in 1990, of its graphics interface, Windows. The success of Windows In any history of the PC, the appearance of Windows 3.0 will merit a new chapter. Earlier versions of the program were glitch-ridden, and even 3.0 presented users with some difficulties, but largely due to the support of other software manufacturers who wrote programs to operate through MS-DOS µlus the Windows 3.0 graphics interface, the Windows market exploded. Over nine million copies had been sold by the end of 1991. This is why Microsoft says "the market has spoken", suggesting that computer users are so happy with their product that they want, or will want, no other. This is a doubtful proposition. But the Windows success prompted Microsoft to pull out of OS/2 development and concentrate on later versions tlf Windows. Version 3.1 came out last month and Windows NT - a 32-bit package - is promised for late this year. Presumably, NT will be the first true Windows operating system, as distinct from an add-on to the basic MS-DOS: which is what versions 3.0 and 3.1 are. Microsoft says that no matter which version you buy, it will always look like what you're used to. The present Windows interface will always be retained - as far into the future as its technical people can see. So why should users buy OS/2 version 2.0 instead of sticking with Windows? There are a few reasons. The first and most dramatic is probably that OS/2 actually includes Windows 3.0 and IBM promises that it will continue to enhance its Windows versions in the package - to match 3.1 and, later, to match NT. How is this possible? It's because IBM and Microsoft signed a development deal for graphic interfaces back in the eighties that gave IBM full rights to all programming codes developed during the course of that agreement. This agreement runs as far as the coming Windows NT, IBM claims, and includes it. So if you like Windows, and want to use it, you now have a choice of buying the Microsoft version or the IBM version. If you buy Microsoft, you will also need to buy MS-DOS, on which Microsoft Windows stands. If you buy OS/2 version 2.0, you will find it includes DOS - and goes beyond it into 32-bit processing. Countless forests have been hewn to bring computer users the first reports on what OS/2 is, and what it does. Here is a simple Q&A that answers some questions about whether it belongs in your computer - now, or in the future. What's the minimum hardware I'll need for OS/2? IBM says this is an 80386SX with 60Mb of storage and 4Mb of RAM. A smaller hard disc may suffice if you are running compression-on-the-flysuch as Sup erStor, Stacker or DoubleDisk. Obviously, the faster your CPU chip , the greater your RAM and the larger your hard disc, the better OS/2 will run. How much disc space will I need? The bare-bones installation occupies 15Mb and there are alternative installations that take you up to 30Mb. The higher-end installations, however, STOCK SALE!! FANS 80 x 80 x 25mm 240VAC .... $16.84 120 x 120 x 38mm 240VAC $16.92 Fan Finger Guards for 80mm Fans ....... ........ .. .. .... $1.43 Fan Finger Guards for 120mm Fans ........... .... .. .... $2.12 MISCELLANEOUS Circuit Breakers 7.5A- Press To Reset .. .... .......... .. ... .... ... $7.25 Mains Power Lead 10A 1.8m long ...... .... ... .......... .... $4.16 9V Battery Snaps .... .. ..... ....... $0.20 2 x AA Battery Holder ... ...... .. . $0.28 12-Way terminal block 10A .. . $1.60 SEMICONDUCTORS 1N4004 Diodes ... ... ......... ...... $0.07 1N4007 Diodes .. ..... .. ... ... .. ... . $0.1 0 1N4148 Diodes ................ ... .. $0.04 MJ15003 Transistor ........ .. .... $6.50 MJ15004 Transistor ........ ... ... $6.50 MJ15024 Transistor ..... ......... $8.60 MJ15025 Transistor ..... .... ... .. $8.60 MJ13007 Transistor ....... .. .. ... $4.87 MFR571 Transistor ..... .......... $4.27 NE555 IC ... .. .... ... ............ .. .. .. $0.30 TL494 IC .... ... .... ...... ... ........... $2.83 MC14514 IC ..... ....... .... ..... ..... $3.00 MC34063 IC ....................... ... $2.98 ALL ITEMS 10 PLUS 10% OFF HY CAL ELECTRONICS Unit 4, 62 Gt. Western Hwy, Parramatta, NSW 2150. Phone (02) 633 5477 Fax (02) 891 5640 Credit Cards Welcome MAY 1992 25 are those including the on-line help, and if you don't have this, your learning curve may be a longer one. There's a type-font program. (These are just the things I found in my review copy. I'm told there's more). How much does it cost? Are any OS/2 application packages in the market? Beats me. The recommended retail price is $275 but you could get it for about $250 on the day it hit the shops. IBM is apparently interested in discounting to get a leg into this market which ultimately can bring them hundreds of millions of dollars. How well does it work? Brilliantly. An IBM publicist said last year that the new package would "run DOS better than DOS and Windows better than Windows". OS/2 certainly does that, for two reasons. One is that it's a 32-bit package - your DOS and Windows applications run faster. The other is that IBM, just like Microsoft, has had about two years to clean up some of the things that trou- Yes. In June last year, you could buy PageMaker, CASE, Carel Draw, Lotus 1-2-3, PackRat, Ventura, WordPerfect and other packages in OS/2 versions. Microsoft was offering Excel and Word. IBM spread its programming codes around for version 2.0, and now claims that 800 applications are now available or in advanced preparation. Note, by the way, that the programs listed here sold for the same prices as the Windows versions in almost every case. Is OS/2 here for the long haul? We don't know whether any of the current systems are here for the long haul. How long a haul are we think- "OS/2 actually includes Windows 3.0 and IBM promises that it will continue to enhance its Windows versions in the package - to match 3.1 and, later, to match Windows NT" bled Windows users with the 3.0 package. I couldn't get any Unrecoverable Application Errors from my OS/2 Windows, for example. Memory management is wonderful. I don't use Windows and don't want to. What's in OS/2 for me? Quite a lot of things. Your DOS programs will run faster. RAM cram vanishes because of the way OS/2 presents DOSwhich is that it sets up a new DOS simulation for every DOS program you get into. These simulations each have something like 630Kb of available RAM. Task switching is better. The REXX programming language supplied is better. And besides, OS/2 is bundled with a lot of things beyond the operating system itself. And these are? There's a database and a spreadsheet. There's a good communications program for modem users. There's a calendar/diary/personal information manager. There are excellent games. There's a 5-disc suite of device drivers, including scads of mouse drivers. 26 SILICON CHIP ing of? It's pretty obvious that OS/2, DOS and Windows are here for as long as we're using x86 Intel CPUs. And IBM has already worked out how to transfer our OS/2 data files to RISC processors. Only a brave or foolhardy person would predict what CPUs we'll be using 10 years from now. How confident can I be that OS/2 works? Pretty confident. IBM issued 30,000 beta copies before release and licensed many of the beta assessors to make up to 10 copies of the beta code. When Microsoft released MS-DOS 5.0 last year, it announced there had been 5000 beta testers - at that time, the largest such program in history. DOS 5.0 doesn't seem to have too many dark and spooky corners. Do I really need OS/2? It's up to you. If you often sit in front of your computer waiting for it to do things, for example, you'll spend less such time with OS/2. If you're crashing your present system often, you should enjoy less crashes under OS/2, because of the improved memory management. If you foresee working with any software that calls for a lot of calculation, you can rest assured that somebody out there is writing or bringing to market a 32-bit version that won't run under DOS. If you're already running a program you want to be faster, check with your program's Australian agent when the OS/2 version will be available. Your DOS or Windows software will be faster within OS/2; your OS/2 application will be faster again: in some cases, much faster. What are the disadvantages? The main one, is that you have to learn it. It's not much fun learning any new software. One of the many charms of Microsoft Windows is that its Program Manager interface slashes the learning time for new applications; but you have to learn the PM interface before you can take advantage of this. In exactly the same way, you have to learn how OS/2 works. The other disadvantage is the high hardware requirement. You may not be able to run OS/2 at all on your present computer. Then again, you may not be able to run Windows NT, either. · How do you see OS/2? My view is that it shows us where the PC is going. Not everybody has to follow this path. If you want a simple business machine for word processing, plus a couple of simple DOS and Windows programs, you can continue happily with an 80286 machine, a couple of megs of RAM, and a 2040Mb hard disc. These machines are really cheap today and will get cheaper in the future. OS/2's ability to run DOS and Windows now, and keep up with Windows even through the NT evolution, is a powerful incentive to adopt the system. And the higher-level machines are also getting cheaper. Coincidentally, just as I was finishing this column, I saw a newspaper advertisement from a well-known clone supplier. It was for an 80486-40 machine with 64Kb RAM cache, 125Mb hard disc and 4Mb RAM- for under $2200. Two years ago, an 80286 with a 40M hard disc, no cache and 2Mb of RAM, could cost you $5000 or more. SC All this month you'll find fantastic new products and sensational value at Dick Smith Electronics! Hurry in today for the latest in kits, books, tools and shortwave rad ios. Bffi~~~~,?- Exceptional performance and specifications make the Playmaster series a popular choice among kit builders. This classic 30/30W stereo amp is no exception; it's superbly engineered and designed to enhance the output of any music system. All components (including heatsinks) are mounted on one PCB so it's easy to build. It comes complete as a full form kit with PCB, hardware, pre-punched rack-mounted case, prepunched silk screened front panel and all components. t~•i=Jifi~-~:! ~;fJi A great idea when there's one VCR and two televisions. Now you can play a video and watch it from another television without connection leads from VCR to TV. All components for UHF or VHF modulator output are included . What's more, it's simple to construct and comes as a full form kit with PCB, all components and front panel label. You'll have to build your own antenna, so PCB's and instructions are also included. Cat K-5700 Cat K-5600 QQ ti i: ift{~l•t◄ ;j 1113~ l·IB i•'-' t•J ;j A high performance yet inexpensive benchtop audio oscillator. It covers the frequency range from around 6Hz to ?0kHz in four ranges with very low distortion. What's more, in terms of practical and general use, this oscillator really delivers. It comes as a full form kit with all components, PCB, case and pre-punched silk screened front panel. Cat K-7340 Mf~1filiilll Active crossovers are an effective way to improve loudspeaker performance. This inexpensive crossover kit includes features found only in systems costing thousands of dollars. To overcome the limitations of passive crossovers the active crossover filter network is shifted so that it precedes the power amplifier. The advantages of this system include; ideal high impedance loads, less discrepancies in speaker driver efficiency and less resistance between the voice coil and amplifier. Short form kit complete with PCB and all components. Cat K-5405 $5995 1:1•)·Milt(•)~il!1ii11;j A low cost multimeter packed with features! It's compact, reliable and great fun to build. With continuity testing, a wide 10A DC range and battery checker. It has 19 ranges plus dB, 20K/V sensitivity, diode and fuse protection. Complete with all components , printed circuit board, quality case, probes and full instruction manual. Ideal for the hobbyist or professional. Cat K-1040 QQ Q t-v ;I I 3•l!l•J ~ i~Ii 13 :j A simple voltmeter that can save you money. It gives a visual indication of the charging system of a 12V battery. The three LED's show if battery voltage is low, correct or high . This way, you can tell if voltage is dropping or if your battery is overcharging . It's super easy to build , includes a small PCB which fits the a 35mm film contain_ er, or your pocket. Cat K-4205 $695 N!W Q B1316 With Cassette Player Listen to the world, local AM/FM stations or your favourite cassettes with this professional dual conversion, all-band world receiver. The Sangean ATS-81 BCS covers AM/FM bands, FM stereo (with optional earphones), Longwave and Shortwave bands. Top of the line features include a 45 station memory, large digital display, BFO control, keypad frequency entry and much morel FEAlURES • Covers AM/FM, Longwave (150 to 519kHz) and Shortwave (1.62 to 29.99MHz) bands • Five tuning methods, including keypad frequency entry and rotary dial tuning • 45 station memory • Easy to use keyboard controls • Dual time display for local and UTC • AM wide/narrow I.F. filters • Pushbutton selection of major SW bands from 120m to 11m • Standby functions for radio, buzzer or recording functions • Adjustable RF gain prevents overloading from very strong signals • BFO (Beat Frequency Oscillator) control for receiving SSB and Morse code transmissions • Dual conversion design for improved receiver performance • Large LCD screen with frequency, time, station preset channel, signal, battery strength and icons. • Pushbutton cassette recorder with Cro2 facility and auto- stop CalD-2842 2 Tools In One! If you thought only Superman had X-ray vision ... think again! The tracker detects wood, metal and live cables through walls, floors, plaster board, chipboard and panelling, etc. It's ideal for locating joints, battens and rafters through walls when Installing pictures, shelves or ceiling fans. As well, you can use it to detect live/dead cables, pipes and mains, etc. A safe and easy alternative to 'blind drilling'. Requires 9V battery. CatT-1990 $399 Rechargeable Get the features, design and specifications of a professional unit at an affordable price. This incredibly easy to use 10Hz to 1.2GHz frequency counter has an 8digit LED display and 3 switchable gate times. It comes with a rechargeable battery and a DC power socket, so you can work and recharge it at the same time. What's more, it recharges in 5 hours and has overcharge protection. It's ideal for measuring radio frequency transmissions as well as servicing stereos, videos, computers and cordless phones. With Hi and Low BNC connectors and calibration adjustment. Includes a full 12 month warranty. Cal Q-1320 Specifications Frequency Range Impedance Max. Voltage Range B Range A 10Hz- 20MHz 20MHz - 1200MHz 1 MEG Ohm,80pf SO Ohm 100Vp-p 5Vp-p Gate Time: 2s, 0.02s, 0.002s Switch Selectable Read Out: KHz or MHz Power: 8.4V rechargeable battery or optional 12V/500mAadaptor, Cat M-9627 B1316 WIRE AND CABLE ·FOR ELECTRONICS .•. . . Nell Sclater The most comprehensive source of information available on topics including the properties of conductors, insulation system design and assembly techniques. What's more, it has guidelines for the latest wire and cable equipment. With international code designations, plus wire and cable specifications for the most simple, through to the most advanced applications. Cat B-1618 Learn from the experts. Tips and winning secrets on how to play the hottest video games around. With storylines, hints and full colour screen shots. It even has game evaluations, so you can read about a game before you buy it. NINTENDO GAMES PLAYER'S ENCVCLOPEDIA VOL 1-3 B-9900/B-9901 /B-9902 $4995 NINTENDO GAME PLAYER'S ENCYCLOPEDIA VOLUME 4 Cat B-9903 Peter Norton & Robert Jourdain ~195 An easy to read book designed for IBM PC users at all levels. PC Problem Solver extends beyond DOS to cover Networks, Communications, Windows 3.0 and DOS 4.0 DOSSHELL programs. With many time-saving tips on utility software and trouble-shooting, from the man who invented Norton Utilities! IBM PC GAMES PLAYER'S ENCYCLOPEDIA'S VOLUME 1-2 Cat B-6800/B-6802 $4995 Cat B-6200 QUE QUICK REFERENCE POCKET BOOK GUIDES Essential and inexpensive! The QUE range of computer guide books are the smart and easy way to solve problems and find specific commands quickly. Though not intended to replace complex user manuals, they cover all the essential information you'll need to get started. li~M-18 r en 11 spaugh A practical insight for children, students or adults interested in aviation and space flight. Dr Millspaugh received the 1989 'Aerospace Teacher of the Year Award' and the 'Award for Excellence in Aerospace Education'. This book contains the very best of experiments devised and presented by his own students. Includes principles of buoyancy, propulsion, atmospheric composition, Newton's laws and more! $1695 Cat B-6702 TITLES INCLUDE: Cat No. Wordperfect 5.1 Microsoft Word 5 MS-DOS 5 Norton Utilities Fastback Hard Disk (DOS 4.01) PC Tools Lotus 1-2-3(Release 3.1) B-6400 B-6402 B-6404 B-6406 B-6410 B-6412 B-6414 B-6408 DS XPRESS PHONE & MAILORDER SERVICE Outside Sydney (FREE Call) 008 22 6610 Sydney And Enquiries • 888 2105 FAX: (02) 805 1986 or wrtte to DS XPRESS, PO BOX 321 N/RYDE NSW 2113 All Major Credit Cards Accepted. O/Nite Courier Available. 24 HOUR DESPATCH OF ALL ORDERS STORE LOCATIONS: NSW • Albury 21 8399 • Bankstown Square 707 4888 • Blacktown 671 7722 • Brookvale 905 0441 • Bondi 3871444 • Campbelltown 27 2199 • Chatswood Chase 4111955 • Chullora 642 8922 • Gore Hill 439 5311 • Gosford 25 0235 • Hornsby 477 6633 • Hurstville 580 8622 • Kotara 56 2092 • Liverpool 800 9888 • Maitland 33 7866 • Miranda 525 2722 • Newcastle 811896 • North Ryde 878 3855 • Orange 618 400 • Parramatta 889 2188 • Penrith 32 3400 • Railway Square 211 3777 • Sydney City 267 9111 • Tamworth 661711 • Wollongong 28 3800 ACT• Belconnen (06) 2531785 • Fyshwick 280 4944 VIC • Ballarat 31 5433 • Bendigo 43 0388 • Box Hill 890 0699 • Coburg 383 4455 • Dandenong 794 9377 • East Brighton 592 2388 • Essendon 379 7444 • Footscray 689 2055 • Frankston 783 9144 • Geelong 232 711 • Melbourne City 399 Elizabeth St 326 8088 & 246 Bourke St 839 0396 • Richmond 4281614 • Ringwood 879 5338 • Springvale 547 0522 QLD • Brisbane City 229 9377 • Buranda 391 6233 • Cairns 311 515 • Capalaba 245 2870 • Chermside 359 6255 • Red bank 288 5599 • Rockhampton 27 9644 • Southport 32 9033 • Toowoomba 38 4300 • Townsville 72 5722 • Underwood 341 0844 •SA• Adelaide City 2321200 • Beverley 3471900 • Elizabeth 255 8099 • Enfield 260 8088 • St. Marys 277 8977 WA • Cannington 451 8888 • Fremantle 335 9733 • Perth City 481 3261 • Midland 2501460 • Northbridge 328 6944 TAS • Hobart 31 08J)O NT• Stuart Park 811977 STORES ACROSS AUSTRALIA AND NEW ZEALAND B1316/LB A low-cost electronic doorbell Has your doorbell broken down? This unit uses readily available parts to produce a realistic & pleasant "dingggdonggg" sound. By DARREN YATES These days, like most consumer goods, doorbells are treated as a "throw-away" item - the cost of repairing one invariably exceeds the cost of buying a new one. If your doorbell has broken down or if you don't already have one, then here's an ideal opportunity to build a deluxe unit for yourself. As you can see from the photographs, we built two versions, one housed in a commercial doorbell case (from Dick Smith Electronics) and the other in a plastic zippy box. Apart from that, the two units are identical. Go for the Dick Smith Electronics version if the unit is to be seen as well as heard. In other situations, the zippy box version may be the more convenient, particularly if the unit is to be hidden from view on top of a cupboard or a bookcase. The last time that we used a 2-tone chime circuit was in the Door Minder project, published in February 1988. That circuit used an SAB0602 2-tone chime IC which has subsequently become hard to get and expensive. This project overcomes that problem by using common CMOS ICs. In fact, parts of the circuitry are similar to the Executive Thingie project in last month's issue. When the front doorbell switch is pressed, this project generates the familiar "dinggg-donggg" sound by sequentially feeding the outputs from two tone generators to a small power amplifier. These tone generator outputs are fed to the amplifier via separate CMOS FETs which act as variable resistors to give the required decay characteristics. Power is derived from a 6V battery pack consisting of four 1.5V AA cells. If you use alkaline types, they should last for about one year or so. Alternatively, you could replace the batteries with a 6V 300mA plugpack and forget about them. Block diagram Refer now to Fig.1 which shows the block diagram of the Doorbell. We'll Left: this view shows the completed electronic doorbell in the commercial case that's available from Dick Smith Electronics. This case has a dark brown front panel with metallic highlights and this attaches by four screws to a cream-coloured midsection. The rear-panel, which is moulded in black plastic, is secured to the wall and the front assembly then clips over it. 30 SILICON CHIP Ii BELL PUSH DEBOUNCE HALF MONOSTABLE HALF MONOSTABLE IC1a IC1b IC1c D1 D2 VOLTAGE CONTROLLED RESISTOR IC2a AMPLIFIER BIAS CONTROLLER VOLTAGE CONTROLLED RESISTOR IC2b [(J SPEAKER HIGH TONE OSCILLATOR LOW TONE OSCILLATOR IC1d IC1e AMPLIFIER 03-06 Fig.1: when the doorbell switch is pressed, the two half monostable stages (IC1b & IC1c) are activated in sequence & apply bias to voltage controlled resistor stages IC2a & IC2b. These stages then modulate the outputs from the tone generators (IC1d & IC1e) & the resulting signals are then fed to an audio amplifier stage (Q3-Q6). due to switch contact bounce or due to spikes generated in the switch leads by nearby lightning strikes or mains transients. From there, the output is then fed into two half-monostables based on IClb and IClc. These provide the correct time delay between the two tones of the doorbell. Each half-monostable is connected to a voltage-controlled resistor network (IC2a & IC2b) and these modulate the outputs from tone oscillator stages ICld & ICle to give the characteristic ringing sound. The outputs from the voltage controlled resistor stages are then fed to the audio ampli- just go through it briefly at this stage, so that you will understand the basics of the circuit. The front doorbell switch is connected to a debounce circuit based on ICla. This prevents false triggering Fig.2 (below): the final circuit uses the FETs from a 4007 IC as the voltage controlled resistors. When S1 is pressed, Ql turns on & provides bias to IC2a which allows through signals from oscillator stage IC1d. Ql then turns off & Q2 turns on to provide bias for IC2b which then passes signals from tone oscillator IC1e. 100 + 16VWJ T 6V 1 + Circuit diagram Let's look now at Fig.2 which shows the complete circuit details. The project is based on two common CMOS ICs and six transistors. Let's start again with the doorbell * 150k I ...I... fier stage (Q3-Q6) and to the loudspeaker. We've pulled rather a neat trick with the audio amplifier stage, however. Because the circuit is powered continuously, we have to make the quiescent current (ie, the current flow when the circuit is in its idle state) as low as possible, to conserve the batteries. By using CMOS ICs in the front end, we have no problems here but we have to control the quiescent current of the audio amplifier. The easiest way to achieve this is to use the half-monostable outputs to control the DC bias of the amplifier via an OR gate (Dl & DZ). When the circuit is in its idle state, the monostable outputs are low and no forward bias is applied to the amplifier. Thus, the quiescent current drawn by the audio amplifier is reduced to zero. Conversely, when either half monostable output is high, the output of the OR gate is also high and bias is applied to the amplifier which then operates as normal. This allows us to keep the quiescent current down to only 160µA. Not bad,huh? 2.2M +6V 01I t14 IC2b 1 OOOR I BELL S1 10 3.3M .,. 8.2k 2.2 + 25VW+ t9 -¥- 12 -:- +6V * 120k +6V 01 + 10k 02 1N914 IC2a 4007 03 BC54& 8. eLJc 2.2 + 25VW+ VIEWED FROM BELOW 10k .,. *SEE TEXT DOORCHIME MAY 1992 31 Fig.3: you can install the parts on the PC board in any order but take care with the orientation & placement of the transistors & ICs. The two resistors marked with asterisks may need adjusting to get the correct tones. switch. The 2.2MO resistor, the 0.lµF capacitor and Schmitt trigger stage ICla form the de bounce circuit. These components clean up the waveform produced by the bouncing switch contacts to give a positive-going pulse on pin 2 of ICla each time the switch is pressed. This positive-going pulse is then AC-coupled to the first of the halfmonostable stages. This stage consists of IClb and its associated 0. lµF capacitor and 4.7MO resistor. Normally, pin 5 ofIClb is held low by the 4.7MO resistor and so its output at pin 6 is high and transistor Ql is off. When pin 2 of ICla switches high (ie, when the doorbell is pressed), IClb is immediately triggered and switches its pin 6 output low. Pin 6 of IClb then switches high again a short time later on the trailing edge of the input pulse, as set by the RC time constant on pin 5. When pin 6 ofIClb goes high again, the second monostable based on IClc is triggered into action. This halfmonostable works in exactly the same manner as the first and switches its pin 8 output low for a brief period. Thus, the two half-monostables work in a sequential fashion, with IClb first briefly switching its output low and then IClc doing the same. Voltage-controlled FETs Transistors Ql and Q2 buffer these outputs and in turn drive the voltage controlled resistor stages IC2a and IC2b. These stages are actually the ~channel FETs from two complementary pairs inside a 4007 CMOS IC. When pin 6 of IClb switches low, Ql turns on and quickly charges the 2.2µF capacitor on its collector. This turns on N-channel FET IC2a by pulling its gate (pin 3) high, so that it now passes signal from tone oscillator stage ICld. When pin 6 of IClb switches high again, Ql turns off and the 2.2µF capacitor discharges via its parallel 680kO resistor. This sets the decay time for the tone oscillator signal. As the voltage across the 2.2µF capacitor decreases, the source-drain resistance of the FET increases so that the signal level on pin 5 decays to zero. Q2, IC2b & ICle operate in exactly the same fashion. When Ql turns off, Q2 immediately turns on and this turns on IC2b which now passes signal from tone oscillator ICle. The two tone oscillators (ICld & ICle) are standard Schmitt trigger configurations with RC feedback components. ICld is the high tone oscillator and ICle is the low tone oscillator. Or, to put it another way, Ql, ICld and IC2a produce the "ding", while QZ, ICle and IC2b produce the "dong". Output amplifier The tone outputs from the FETs are mixed via two 10kO resistors and coupled to the base of Q3 in the audio amplifier via a 0.22µF capacitor. A .033µF capacitor then filters the waveform on Q3's base to give it a more "mellow" sound. The audio amplifier is a fairly standard 4-transistor class B arrangement but note that no fixed bias is applied CAPACITOR CODES (10%) 0 0 0 0 0 Value IEC Code EIA Code 0.22µF 0.1µF .033µF .01µF 220n 100n 33n 10n 224K 104K 333K 103K RESISTOR COLOUR CODES 0 0 0 0 0 0 0 0 0 0 0 0 0 32 No. Value 4-Band Code (1%) 5-Band Code (1%) 1 4.7MO 3.3MO 2.2MO 680k0 330k0 220k0 150k0 120k0 10kO 8.2k0 6.8k0 1.5kO yellow violet green gold orange orange green gold red red green gold blue grey yellow brown orange orange yellow brown red red yellow brown brown green yellow brown brown red yellow brown brown black orange brown grey red red brown blue grey red brown brown green red brown not applicable not applicable not applicable blue grey black orange brown orange orange black orange brown red red black orange brown brown green black orange brown brown red black orange brown brown black black red brown grey red black brown brown blue grey black brown brown brown green black brown brown 2 1 1 1 4 2 1 2 SILICON CHIP The PC board is secured to the rear panel of the DSE case on 25mm tapped standoffs. Note that the lOOµF capacitor at top right is mounted with its body flat against the PC hoard so that it clears the loudspeaker. to Q3 or to the complementary output pair (Q5 & Q6). Q3 is wired as a common emitter amplifier and provides most of the voltage gain. Its collector output drives Q4 which in turn functions as a driver stage for Q5 and Q6. Note that the bottom end of Q6's 1.5kQ base bias resistor has been connected to the output rather than to ground. Because Q5 and Q6 together function as an emitter follower with a voltage gain of almost unity, there is almost no AC voltage across the 1.5kQ resistor. This means that very little signal current flows in the resistor and thus its impedance does not load the output of the preceding stage, Q3. This technique is called "bootstrapping" and it results in greater signal output. The gain of the amplifier is set to approximately 4.5 by the ratio of the 6.8kQ and 1.5kQ feedback resistors. The amplified audio signal appears at the emitters of Q5 and Q6 and is coupled to the loudspeaker via a 100µF capacitor. Bias control The DC bias control circuit for the amplifier is quite simple but very effective in reducing the quiescent current to zero under no-signal conditions. As mentioned earlier, it is based This view shows how the batteries are hidden in one channel of the DSE case. The front & mid-sections of the case are held together by four self-tapping screws. on diode OR gate Dl and DZ. This OR gate drives a voltage divider consisting of ZZ0kQ and 330kQ resistors. The voltage developed at the junction of this voltage divider then provides the DC bias for the audio amplifier. Let's see how it works. When Sl is pressed, Ql immediately turns on as described previously and pulls Dl 's anode high. Thus, the output of the diode OR gate also goes high and this applies approximately 3.ZV of DC bias to the base of Q3 via the voltage divider. Similarly, when Ql turns off and QZ turns on, the output of the OR gate is pulled high via DZ and base bias is applied to Q3 as before. When the output of the OR gate subsequently goes low (ie, at the end of the two tones), the lOµF capacitor immediately begins discharging via the ZZ0kQ and 330kQ resistors. This progressively removes the DC bias from Q3 over a 5-second period, thus effectively shutting the amplifier down until the button is pressed again. By the way, if the doorbell switch is pressed and held down, the Doorchime will only operate once and then stop. That's because IClb can only be triggered when pin Z ofICla switches from low to high (ie, the change of state is necessary to trigger IClb). Thus, to get the Doorchime to sound repeatedly, it is necessary to repeatedly press the doorbell switch. Board assembly Fig.3 shows the parts layout on the PC board. This board is coded SC031069Z 1 and measures 108 x 74mm. Before starting the assembly, check The four plastic ribs on the back of the front section must be snapped off before the final assembly, to provide clearance for the PC board. MAY 1992 33 Now for the big test. Connect the loudspeaker, bell push (S1) and battery connector to the PC board, then snap the battery into position. If everything is OK, the circuit should trigger immediately power is applied. After that, you will have to press S1 to trigger the unit - disconnecting and reconnecting the battery will not do the job unless you discharge the lO0µF filter capacitor across the supply. Adjusting the tones A plastic zippy case can be used to house the PC board if the unit is to be hidden out of sight (eg, on top of a cupboard or bookshelf). the board carefully by comparing it with the published pattern. If you find any defects, correct them immediately, then install the four wire links. Make sure that the links are straight, so that they don't short against other parts. Once the links are in, you can install the resistors, diodes and capacitors. The two resistors marked with asterisks should be soldered to PC stakes and not directly to the board itself. This makes it easy to make adjustments to the tone oscillators, as we'll explain later. The accompanying table shows the resistor colour codes but it's also a good idea to check them on your multimeter before installing them on the PC board. Make sure that the diodes and electrolytic capacitors are correctly oriented. Finally, you can complete the board assembly by soldering in the ICs and the transistors. Be sure to use the correct transistor type at each location, as both NPN and PNP types are used in the circuit. Fig.2 shows the pin connection details for the transistors. Install a plug and socket in series with the battery leads if you are using the DSE case, so that you can easily separate the front section from the rear panel assembly. This will make it much easier to replace the batteries when they eventually go flat. 34 SILICON CHIP At this stage, the tones might sound a bit ''wonky" but that's easily fixed by changing the values of the feedback resistors in the tone oscillators (ie, those marked with asterisks). You simply increase the resistor values for lower tone frequencies and decrease them for higher frequencies. For example, to lower the frequency of the "dinggg", increase the value of the 12okn feedback resistor in the high tone oscillator. If you're the cautious type, then connect your multimeter (set to the mA range) in series with one of the battery leads before initially applying power. It should indicate a peak current of about 40mA as the doorbell sounds, but this should then rapidly fall away to about 160-170µA after 10 seconds or so. If you get any readings other than these, (eg, if you get a current of 40mA or more continuously), switch off immediately and check for wiring errors. In particular, check for incorrectly oriented parts and for shorts on the copper side of the board (eg, shorts between adjacent IC pads). Final assembly Once the circuit is working correctly, you can install it inside the case. If you're using a plastic zippy case, first attach the adhesive label to the front panel and drill out a pattern of 5mm-diameter holes to let the sound escape from the loudspeaker (note: drill small pilot holes first). The loudspeaker can then either be glued•in position or secured to the lid using two small aluminium brackets, machine screws and nuts (see photo). The PC board is mounted on the bottom of the case at one end, so that it sits underneath the loudspeaker. Check that there is enough room at the other end of the case for the batteries before drilling the mounting holes. 91 n (/) C) w ~ C) (J'I "°nJ Fig.4: this is the full-size etching pattern for the PC board (code SC03106921). The board can then be mounted in position on 5mm spacers and secured using screws, nuts and star washers. The assembly can now be completed by drilling a small exit hole in the side of the case for the leads to the doorbell switch . .These leads can be made as long as is necessary to connect the unit and doorbell switch together. The alternative Dick Smith Electronics case is a 3-piece assembly of moulded plastic. The front piece is dark brown with m etallic highlights and this attaches by fo ur screws to a cream-coloured mid-section. The rearpanel, which is moulded in black plastic , is secured to the wall and the front assembly then clips over it. If you're using the Dick Smith Electronics case, it's simply a matter of gluing the loudspeaker into the mould on the rear panel and mounting the PC board over it on 25mm-long plastic standoffs. These standoffs are mounted on either side of the loudspeaker and the m ou lded battery holder (see photo). Don't forget to connect the loudspeaker leads before mounting the PC board with its co de number adjacent to the loudspeaker. Battery arrangement The zippy box version has a series of 5mm-diameter holes drilled in the front panel to allow sound to escape from the loudspeaker. The battery holder moulded into the rear panel is not used here. Instead, the batteries are clipped into a separate long holder which is cleverly hidden in one of the channels that run down both sides of the case. You gain access to these channels by undoing the four screws that hold the front and middle sections together. The battery holder is installed in the righthand channel, as viewed from the back, and the leads passed out through the cutout in the centre of the channel. By the way, it is a good idea to install a plug and socket in series with the battery leads so that you can easily separate the section containing the batteries from the rear panel as- PARTS LIST 1 PC board, code SC03106921, 108 x 74mm 1 plastic zippy case, 150 x 90 x 50mm; or 1 commercial doorbell case from Dick Smith Electronics (see note 1) 4 1.5V AA cells (alkaline) 1 4 x AA battery holder (square for zippy case, long for DSE case) · 1 75mm 8-ohm loudspeaker 1 front doorbell switch (DSE Cat. P7554; Jaycar Cat. SP-0780) 4 5mm spacers (25mm for DSE case) Semiconductors 1 74C14 hex Schmitt trigger inverter (IC1) 1 4007 complementary pair plus inverter (IC2) 3 BC558 transistors (01 ,02,04) 1 BC548 transistor (03) 1 BC337 transistor (05) 1 BC327 transistor (06) 2 1N914 signal diodes (D1 ,D2) Capacitors 2 100µF 16VW RB electrolytics 1 10µF 16VW RB electrolytic 2 2.2µF 25VW RB electrolytics 1 0.22µF 63VW MKT 4 0.1µF 63VW MKT 1 .033µF 63VW MKT 2 .01 µF 63VW MKT Resistors (0.5W, 1 4.?MQ 5% 1 3.3MQ 5% 1 2.2MQ 5% 2 680kQ 1 330kQ 1 220kQ 1%) 1 150kQ 1 120kQ 4 10kn 2 8.2kQ 1 6.8kQ 2 1.5kQ Miscellaneous Tinned copper wire; insulated hook-up wire; figure-8 bell cable; machine screws, nuts & washers. Note 1 : the Dick Smith Electronics doorbell case is available only as part of a complete kit. sembly. This will make it much easier to replace the batteries when they eventually go flat. Finally, it is necessary to remove four plastic ribs from inside the case before clipping it over the rear panel assembly. These ribs can be easily snapped off by hand. SC MAY 1992 35 Don't spend big bucks on batteries for your Sony Walkman ®. This simple voltage regulator will let you power it from a plugpack supply or from your car's cigarette lighter socket. The If you like listening to your personal player in the car or while relaxing in your favourite chair, then this project is a must. It's a very simple voltage regulator circuit that's designed to conserve the player's batteries for those times when you want to listen "on the move". We've christened the project The Eliminator because that's just what it does - when it's plugged in, it effectively eliminates (or bypasses) the player's internal battery. In use, The Eliminator is simply connected between a plugpack supply (or car battery) and the player's DC socket. Its job is to accept the +12V (nominal) from the 36 SILICON CHIP By MARQU E CROZMAN plugpack supply and regulate it to the DC voltage required to run the player. Because it only uses low-cost parts, the savings in batteries will very quickly pay for this project. It's also a snack to build and get going. In fact, we reckon that even a rank beginner could build this design. The circuit can also be easily customised to meet your requirements. Some personal players require two AA cells (3V), while others require three (4.5V) or even four (6V). For this reason, we've designed the project so that it can deliver either 3V, 4.5V, 6V or 9V. All you have to do is select one resistor value from a table. An important safety aspect of this project, particularly for beginners, is that no mains wiring is required. Instead, it's designed to run from a car battery or from a DC plugpack supply. You can use any DC plugpack supply with a rated output voltage of 9-12V. However, the project is not just confined to powering personal players from a DC supply. Because it was originally intended for use in a mainspowered project, the PC board also has provision for a four-diode bridge rectifier. By adding this bridge rectifier, the circuit can be powered from a 15VAC (or less) mains transformer. In this application, however, the 02 1N4004 ~.....__ _ _ _ _ _ _ _,-..,-•3V D3 1N4004 10 + 16VW - Fig.1: the circuit is based on an LM317 3-terminal adjustable regulator. The output voltage can be varied between 3V & 9V by choosing the value ofR2, as shown in Table 1. LED1 OVO---,.__ ___.,_ _ _ _ _ _ _ _ _ _...,.._OV THE ELIMINATOR TABLE 1 R2 Output 180 ohms 3V 330 ohms 4.5V 470 ohms 6V 750 ohms 9V four diodes in the original bridge rectifier have been replaced by a single diode (Dl) and a wire link. We don't need the bridge rectifier, since we are using a DC supply only. Circuit details Refer now to Fig.1 which shows the circuit details. As you can see, The Eliminator is based on an LM317 3-terminal positive voltage regulator. This device is capable of delivering up to 1.5A (with adequate heatsinking), has an output voltage range from 1.2-37V, and features internal thermal overload and short circuit protection, In short, it is virtually "blow-up" proof. Let's take a closer look at how it works. The+ 12Vrail from the plugpack (or car battery) is applied to the input of the LM317 regulator via reverse polarity protection diode Dl. In operation, this regulator is designed to provide 1.25V between its OUT and ADJ (adjust) terminals but note that the current flowing through the ADJ terminal is negligible. This makes the device extremely easy to use, since we require just two resistors to set the output voltage. Since the voltage between the OUT and ADJ terminals is fixed at 1.25V, it follows that the current through Rl and R2 is also fixed. This gives a simple formula for the output voltage, as follows: V001 = 1.25(1 + R2/Rl) In our circuit, Rl is fixed at 120Q while R2 is selected from Table 1 to give the required output voltage. In our case, we used a value of 180Q to obtain a 3V output. If you want a 4.5V, 6V or 9V output, then just select the appropriate resistor value from Table 1. Alternatively, you could replace R2 with a lkQ trimpot to make the output continuously variable over the 1.259V range. A lO0µF electrolytic capacitor is used to filter the incoming supply PARTS LIST 1 PC board, code SC04104921, 48 x 61mm 1 aluminium case 100 x 58 x 45mm (Jaycar Cat. HB-5100) 1 Dynamark front panel label, 55 x 190mm 4 68A x 10mm machine screws, nuts & lock washers 6 PC stakes 1 200mm length of medium~duty hook-up wire Semiconductors 3 1 N4004 diodes (D1 -D3) 1 LM317 voltage regulator 1 5mm LED (LED 1) Capacitors 1 100µF 25VW PC electrolytic 2 10µF 25VW PC electrolytic Resistors (0.5W, 1%) 1120Q 1 R2* * The value of R2 must be selected · from Table 1 or a 1kQ trimpot can be used instead voltage, while the output of the regulator is filtered by a l0µF capacitor to ensure stability. Notice also that the ADJ terminal is bypassed using a second lOµF capacitor, to improve the ripple rejection. D2 protects the LM317 from any reverse voltages which may generated across the output by inductive or capacitive loads, while D3 discharges the lOµF capacitor on the ADJ termi- li:i "'... C> ~ u c,i ov--1 +T2v- D1 ~ 9,oouF + Fig.2: the circuit is shown here wired for a 3V output but this can be varied by changing the value of the 180Q resistor (see Table 1). Mount the LM317 regulator at full lead length & with its metal tab adjacent to the edge of the PC board. Fig.3: here is the full-size etching pattern for the PC board. MAY1992 37 TABLE 2 Brand Plug Size Sanyo 1mm Sony & Aiwa 1.3mm Casio 1.6mm JVC 3.1mm Others: generally 2.1 mm or 2.5mm Note: there is no fixed convention as to which terminal is positive & which is negative. Check the socket of your player - there is usually a small diagram next to it to indicate the wiring polarity The PC board is mounted on the base of the metal case & secured using machine screws, nuts & spacers. Take care with the polarity of the external leads. nal if the output is short circuited. Finally, LED 1 and its associated 3300 current limiting resistor provide power on indication. Construction All the parts are mounted on a small PC board coded SC04104921 - see Fig.3. Begin the assembly by installing PC stakes at the six external wiring points, then install the wire link. You now have to select RZ from Table 1 to obtain the required output voltage. We wanted an output voltage of 3V, so we used a value of 1800 as shown in Fig.3. If you want an output voltage of 6V, for example, just substitute a 4800 resistor instead. The remaining resistors can now be installed, followed by the diodes and the capacitors. Make sure that the diodes and capacitors are oriented ex- actly as shown in the diagram. Finally, the LM317 regulator can be installed. Mount it with its metal tab towards the edge of the board and leave its leads at full length. The completed board assembly is housed in a small metal case which also acts as a heatsink for the LM317 regulator. Mark out and drill the three mounting holes in the base to accept the PC board, then mount the board using 5mm spacers, machine screws and nuts. When the board is in place, mark the mounting hole for the LM317 on the side of the case, then remove the PC board and drill the hole to 3mm. Carefully deburr this hole so that you get a perfectly smooth surface, then reinstall the PC board in the case. Fig.5 shows the mounting details for the LM317. As shown, its metal tab must be isolated from the case using a mica washer and insulating bush. Smear both sides of the mica washer with heatsink compound before bolting the assembly together. When this has been done, use your multimeter (set to a high resistance range) to confirm that there is no connection between the tab and the case. If the meter indicates a short, remove the assembly immediately and locate the source of the problem (eg, a piece of metal swarfmay have punched through the mica washer). Next, attach the adhesive label to the lid and drill a hole to accept the LED bezel. This done, mount the LED in position and connect it to the PC board using short lengths of hook-up wire. Take care with the LED polarity INSULATING MICA WASHER ·"·~)I SCREW r Dllilill(3 ----CASE t T0220 DEVICE The Eliminator Fig.4: this is the full-size artwork for the front panel. 38 SILICON CHIP Fig.5: the LM317 3-terminal regulator must be isolated from the case using a mica washer & insulating bush. Smear all mating surfaces with heatsink compound before bolting the assembly together, then use your multimeter to confirm that the metal tab has been correctly isolated from the case. correct - the polarity indication will usually be moulded into the plastic adjacent to the socket. For in-car use, the input lead is simply a length of figure-8 cable attached to a cigarette lighter plug. Again, make sure that you get the polarity correct. If a plugpack supply is used, tbe input lead will come directly from the plugpack itself. You can either connect the plugpack supply to The Eliminator via a DC socket mounted on the side of the case or you can solder the wires directly to the PC board. The LM317 regulator uses the case as a heatsink. Make sure that it is electrically isolated from the case as shown in Fig.5 . MARK ONE COMMUNICATIONS Specialising in: Mitsubishi , Motorola & NEC mobile phones INSTALLATION & SERVICE 7DAYS . Testing Double check all wiring and component orientation before you assemble the case. All OK? If so, screw the two halves of the case together and connect the unit to your 12V power supply. If everything is working OK, the LED will come on. Check the output voltage and polarity with your multimeter- it should be very close to the selected value. Alternatively, if you substituted a lkQ trimpot for R2 , you simply adjust the pot until you get the desired output voltage. SC - the cathode lead is the shorter of the two (see Fig.1). The assembly can now be completed by installing the input and output leads. These are fed through holes in the ends of the case and secured by cordgrip grommets. You will have to fit the output lead with a DC plug to suit your particular player (see Table 2) . Make sure that you get the polarity obile Phone 18) 29 5888 18) 21 4555 275 Ryedale Rd, Eastwood, NSW2122. Motorola Micro-T•A•C Cellular Telephone Phone (02) 489 7777 Fax (02) 489 7774 Introducing the Protel advantage. Prate({or Windows: Protelfor Windows is an entirely new Printed Circuit Board design system created f or Windows 3. Protelfor Windows brings the professionalism of Protel's proven PCB design sofware to the highly productive Windows 3 environment. New Prate/ users will start designing sooner and experienced users will work more efficiently than eve,: In 386 advanced mode, Windows 3 provides virtual memory capability, which allows advanced PCB users to design without restrictions on the total number of components, nets, tracks , etc. Protelfor Windows supports the multiple document Copper Trace Layers - IZI Top □ Mid 1 D Mid 3 0Mid4 5 □ Mid D Mid 6 □ Mid 7 ---, ---, Visible • □ Mid 8 0-Mid 9 liffl □ Drill Guide - □ Drill Draw • □ DRC Errorsl!III IZI Grid 1~ □ Rats Nest • IZI Grid 21111111 - D Ill IZI Keep Outs - Selections Mid 10 c;] D Mid 11 - □ Mid12 D □ Mid 13 □ D 18] Multi Layer[3:J Background • D Mid 14 11111. D □ Mech 1 - 0 Mech 3 D Mech 2 D Mech 4 - - • D Bottom I . - 1111 □ Dithered Colors Bottom - - D inte1face (MDI) standard. Any number of files can be loaded at the same time, using standard Windows routines, to move information between different fi les or different applications . The Prote/ fo r Windows faimily consists of Advanced PCB - IZI Transparent [Mechanical Layers ---IZI -----, [ft - ISolder Mask I D Top S p e c i a l - - - - -- advanced level PCB layout - $1990 . Options: Advanced Place $995, Advanced Route $995, Advanced Pack* - $3490. Select P,i,.e, • IPo,tSc,ipt P,inte, on LPT1 , Batch Mode 0 Seperale Page For Each Print 0 Composite P,_int <at> Panels (Multiple Layers Per File) ~ Border Between P,tnts ■ Technology Scale P,intScale Protel Tech11ology Pty Ltd PO Box 204, Hobart Tasma11ia 7001 Pho11e (002) 730100 Fax ( 002) 730944 Tollfree 008 030 949 ~ X Conection ~ Y Conection 10.995 I *Includes all 'Advanced' options. Prate! is a registered trademark. Advanced PCB and Prof essional Schematic are registered trademarks of Prate! Technology Pty Ltd . Windows is a registered trademark of Microsoft Corporation Inc. MAY 1992 39 Five faults all at once! A heading like that is hard to ignore. Likewise the customer's claim as she went through the list of faults. Superficially, at least, it was a formidable list and I could only hope that it wasn't as bad as it sounded. The device in question was a Panasonic TC-2969 TV set, an upmarket unit which first appeared about four years ago although this particular set is only about three years old. It is a 73cm model featuring, among other things, an elaborate remote control unit. ·It has been a very popular set. My dealer colleagues, between them, have probably sold around 150 in this area but the number of faults I have encountered has been extremely small. This set belongs to one of my longstanding customers, an elderly widow, but most of my dealings were with her daughter and son-in-law, who were better able to transport the set and describe the various faults. I have had one previous call to this set but that was hardly the set's fault. FRACAR ·AVE ••• ... more than $10. from every UHF television antenna you buy. Fracarro's ====- 4PUN for better performance from weak UHF signals. Peter C. Lacey Services Pty. Ltd. P.O. Box 678 (74Fulton Rd.) Mount Eliza 3930 Tel:03 787 2077 Fax:(03) 787 3460 ACN006893438 40 SILICON CHIP and enjoying a TV program when the screen suddenly went black. But it wasn't a shut-down as in fault number one because the sound was still running and there were traces of the brighter colours on the screen. This was something new and it fi~ nally convinced them to seek my help. So there we had it - five different intermittent faults. Naturally, there wasn't any point in trying to tackle a problem like that in a lounge room; it had to come into the workshop. Fortunately, the son-in-law had a ute and plenty of help on hand to load the set into it. And so it finished up on my counter. About 12 months ago, it was the victim of a lightning strike to the power lines which, as well as damaging the set, knocked out a microwave oven, the electric stove and the hot water system. In fact, about the only thing that escaped in the household was the video recorder - a typical Murphy touch. My first insight into the problem Related faults was a phone call from the owner's Now tracking down any one of daughter, who proceeded to list all those faults could be a nasty job. But the faults it was exhibiting. And, as was tracking down five going to be already intimated, it was a formida- any harder? Not necessarily. In fact, it ble list. didn't need Sherlock Holmes to deThe first fault appeared not long duce that all five faults were almost after I had serviced it and took the . certainly related; find the cause of form of occasional spontaneous shut- one and you'd probably find the cause down; ie, the set would simply turn of them all. itself off. But while this was mildly That was the bright side. The dark annoying, it wasn't regarded as very side was that it was still an intermitserious; it needed only a touch of the tent and likely to take a lot of time to remote on/ off control button to turn it track down. I started by simply turnback on. ing the set on as it came in and, sure Fault number two caused the set to enough, the number five fault just randomly change channels, again in- described was still in evidence; ie, termittently and also easily remedied normal sound but a dark screen with via the remote control. just a hint of colour. And, by using the Fault number three could be al- remote control unit, I could change most rated as two faults: random channels, as evident by the sound. changes of brightness, or the same It is necessary to digress here, so effect on colour saturation. that the reader can follow the next Fault number four was a fairly re- step. As is common with many upcent manifestation. It had happened market sets, this set's remote control on only a couple of occasions but was system offers a multitude of functions; somewhat more serious. As the daugh- far more than most people find necester described it, it was " ... a kind of sary and more than some people can blurting noise; frighteningly loud. handle. Nearly scared Mum out of her wits". In this case, the controls include And then she went on to describe the usual on/off button, 10 channel fault number five which had occurred selecting buttons, an up/down button the previous evening. She and her which takes the set through the chanhusband had been visiting her mother nels one-by-one, a button to allow a channel number - up to about 30 - to be keyed in, volume up/down, stereo sound enable/disable, video up/down and audio up/down. Suitably activated, the video up/ down provides a choice of brightness, contrast and colour saturation control. The audio up/down operates similarly, providing bass, treble and balance control. And any settings selected by these controls are held after the set is turned off, or even unplugged from the mains. There is also a TV /VCR switch which allows the control unit to be used on a Panasonic VCR. It provides all the usual VCR control functions: stop, rewind, fast forward, record, etc. Then there is a another group of five buttons. Button 1 switches from TV to video input; button 2 is a timer, to shut the set down after a selected time; button 3 displays the channel number in the top right corner of the screen; button 4 provides sound mute (now what would anyone want that for?); and button 5 is marked "N" (for normalising). Complicated? You bet it is. And many a viewer has got himself into a hopeless mess trying to cope with all those facilities. In particular, it is all too easy for the beginner to black out the screen or mute the sound, and then forget how to undo it and go into panic mode. Hence the above mentioned "N" button, which is almost an admission of the extreme complexity. It effectively cancels all the control instruc- TETIA TV TIP Samsung TV chassis No. PSOF & RM101 (used in Samsung, Tempest, Akai and Toshiba models) Symptom: picture size is small and pulsates, never quite filling the screen. The 125V rail is low but shows no sign of fluctuation. Reducing the picture contrast stops the pulsation but does nothing to increase the size. Cure: STR30125 voltage regulator IC defective. This is the main cause tions that have been fed in and takes everything - brightness, contrast, colour saturation, sound settings, etc back to their mid-position (or "normal") settings. From there, the user can start all over again. Back to the interruption That brings us back to where I interrupted myself; with the set on the bench with' normal sound but only a few spots of colour on a black screen. I hit the "N" button and up came the picture with normal brightness, contrast and colour. I then tried something else. Using the remote control, I activated the brightness function and wound it down to minimum, then did the same for the contrast. And that exactly duplicated the condition of the set when it came in. All this was quite significant. It sup- of the small picture - the pulsation is a secondary effect produced by the low rail voltage on the Automatic Beam Current Limiter. Resetting the contrast has the effect of reducing the beam current, so the pulsation stops. TETIA TV Tip is supplied by the Tasmanian branch of the Electronic Technician's Institute of Australia. Contact Jim Lawler, 16 Adina St, Geilston Bay, 7015. ported a theory I had been toying with from the start: that the fault was not, as might have at first been imagined, in the remote control system itself. Rather, something was "telling" the microprocessor to do these things - in this case to turn down the brightness and contrast. That "something" could be almost anywhere in the set. All I had to do was find it. I let the set run all day and every day for about a week. During that time, it exhibited almost all of the faults listed above; all, in fact, except fault number four (the distressing blurting noise). More importantly, I confirmed that these effects were totally random; they didn't appear to be related to temperature, period of operation, operation of other appliances on the same power circuit or, in fact, anything that I could pin down. But that very randomness created a gut feeling that it was due to a dry joint somewhere in set. The back was already off the set and so, armed with my favourite sledgehammer, I set to work. (The sledgehammer is really just a large screwdriver, the plastic handle of which is the right weight to deliver an appropriate blow to the circuit board). Looking into the back of the set, there is a large horizontal board, about 350 x 200mm, in the bottom of the cabinet. This carries the power supply and the horizontal and vertical output MAY 1992 41 SERVICEMAN'S LOG - CTD stages . On the lefthand side there is a similar size signal processing board which is mounted vertically. This carries the tuner, IF strip, stereo decoding, remote control processing (but not the receiver), and the audio/visual inputs and t;mtputs. On the righthand side there is a smaller board, about 150 x 100mm, which carries additional horizontal components and the pincushion correction components, etc. I tackled the horizontal board first, starting on the lefthand side, tapping moderately hard and watching the screen in the mirror. No joy. I made my way across to the righthand side , again without any result until I tapped the horizontal output transformer, which is at the right rear of the board. Suddenly, there was a reaction. I can't remember which fault it was, or whether there was more than one, except that it probably changed channels. Anyway, it was what I was after. Well, that was encouraging. The only snag was , I couldn't repeat it. No matter how hard I bashed after that, there was no response. I left it for a while , tried again, left it, tried again, and so on for more times that I can remember. The result was, at best, "iffy"; a couple of times I achieved a briefresponse but nothing consistent. Nevertheless, it did seem to suggest that the fault was not on the board, but somewhere nearby, and that the vibration I was imparting to the board was being transferred to it. So what was closest? There is an "L" shaped aluminium plate near the horizontal output transformer, best envisaged as lying on its side, with the longer section, about 200mm long and 80mm high, running from the back towards the front of the set. The shorter section, about 40mm long, runs parallel with the back of the cabinet and provides the support. One of this plate's functions is as a heatsink for the horizontal output transistor, which is mounted towards the AUSTRALIAN MADE TV TEST EQUIPMENT 10% discount on all test equipment. 15% discount on two or more items. SHORTED TURNS TESTER Built-in meter to check EHT transformers including spl it diode type, yokes and drive transformers. $78.00 + $4.00 p&p rear. It also carries a heavier, finned heatsink at the front for the power supply regulator IC and a couple of large resistors. And when I tapped this, ever so gently, the set "went mad", changing channels and varying brightness, contrast and colour. But then it, too, settled down and I went back to the main board again. But no joy here either. So over the next few hours, in between other jobs, I went through several tapping sessions. I achieved some briefresponses but, more importantly, I concluded that the aluminium bracket was the more sensitive of the two, although the point to be tapped was most critical. And it was while I was establishing this critical point that I encountered fault number four; the blurting sound. And it was only then that I fully appreciated why it had "nearly scared Mum out of her wits". With my head half inside the cabinet while I was probing, it must have hit my eardrums at about lOdB above the threshold of pain and it came close to having a more drastic effect on me than it had on "Mum". ANTRIM TOROIDAL TRANSFORMERS rllGH-VOLTAGE PROBE Built-in meter reads positive or negative voltages from 0-50kV. For checking EHT and other HT voltages. $98.00 + $5.00 p&p DEGAUSSING WAND Strong magnetic field . Double insulated for your safety with momentary switch operation. 240V AC 2.2 amps . As important as a soldering iron! $75.00 + $10.00 p&p REMOTE CONTROL TESTER Designed to test infrared or ultrasonic . control units. Supplied with extension ' infrared detector lead. Output is via a LED and piezo speaker. $84.00 + $4.00 p&p s: ---s ·s --.../'~ / ,__----~ --~ ~ TUNER REPAIRS ~ ~z ~ .,..'I From $19 exchange plus post & pack Cheque, Money Order, Visa, Bankcard or Mastercard 216 Canterbury Rd, I _- .!.. TUNERS , ':::..I Phone (02) 774 11 54 42 SILICON CHIP Revesby, NSW 2212, Australia. Fax (02) 774 1154 • • • • 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 LTD 90 George St, Hornsby, NSW 2077. Phone (02) 476 5854 Fax (02) 476 3231 What happened next was I ') more fortuitous than scientific. I,, The set was on a bench near one of the windows and, in the late afternoon, the sun ~ shines directly into my eyes. I have a blind fitted to take care of this situation and this darkened the area considerably but . .~ it was still light enough to see ,~-what I was tapping. And so I had another go at q~:==::.i--:;;-~·"V'·> .• the aluminium bracket. After -~~~ a couple of tries, I found the sensitive spot again and the set gave forth with another raspberry. This time, fortunately, I had moved back a little, so it wasn't quite so traumatic. oWl-,-H r,/\'-( 1-tG:Ai;> l~SI?~ "fl1E: But, more importantly, I INE:"i" J: E-Na::>ul\J"'t1::;..~e;D happened to be looking at the L.: i 1\-\~ 1)\-Sl'f<G:S'SlNG right spot at the right time. "BLURTING NOi The horizontal output transistor is in a TO-3 case, connected quick fix was out of the question. And to the main board via three flying SC5326, which uses the "Q" chassis. leads. The base and emitter leads are The "Q" chassis is a mite long in the so the customer had no option but to soldered directly to the appropriate tooth now; it first appeared at least 10 leave it with me. pins but the collector lead is con- years ago and remained current, with A little later, I turned the set on nected to the case via a solder lug minor variations, for several years. again and studied the problem more secured under one of the mounting This particular set has been through leisurely. I still couldn't make sense the workshop several times, mainly of the hold control behaviour, so I screws. At the instant the system took off, I for minor faults, but is still in good decided to disconnect the line to the was looking at this solder lug. And nick and has a few years of life left in sync separator and let the vertical circuit float. Normally, this would enthere it was - a tiny spark, clearly it yet. Initially, the owner contacted me able me to roll the picture slowly in visible in the subdued light. From there on it was routine. Closer exami- by phone and, from the symptoms either direction and even hold it nation confirmed that what was sup- described, it appeared that the pic- briefly (with a little care). posed to be a soldered connection · ture was rolling very rapidly. When I The vertical functions are provided between the lead and the solder lug suggested that he try adjusting the by IC401 (LA7800) and the video and was no such thing; it was a classic dry vertical hold control - on the front of sync pulses come in on pin 14 via the set - he replied that he had done number of components, including joint. And that was it; a few moments that, but that it didn't seem to make R402 (220Q) which was fairly easy to get at. It was also a convenient access work with some flux and a hot iron any difference. This clearly indicated that it was point for the CRO and this indicated produced a proper joint and all the problems were solved. It was almost not a simple case of maladjustment, that the waveform was correct. So I lifted the resistor and tried the hold an anti-climax, except that I had the so I said "bring it in". When it arrived, I switched it on for a preliminary check control again. satisfaction ofknowing that I had fiwhile the customer was still there. nally cracked it. The result was rather strange. IniThis confirmed the customer's obser- tially, the effect was much the same as But there was one puzzling aspect. vations and also seemed to confirm before, with the picture rolling rapI would normally expect such a fault, idly upwards. But it was now floating in that position, to take out the tran- my interpretation of them; that the sistor. So why had it survived? I dunno picture was rolling very rapidly up- and, by backing off the vertical hold please; ask Murphy. · wards. control, I was able to make it roll I tried the vertical hold control but quite smoothly and under perfect conConfusing symptoms it had only a very slight affect on the trol. Well, that was better than before. My next story involves a 53cm AWA upward movement in one direction. But it was when I tried to roll it colour TV set and some very confus- Rotating the vertical hold control in slowly upwards that it baulked. I could ing symptoms. Indeed, symptoms are the other direction then caused the hold the blanking bar at the bottom of not always what they appear to be at picture to suddenly reverse direction the screen and move it slowly upwards until it was about half way up first glance. And if you don't get the and roll rapidly downwards. Well, I hadn't seen anything like the screen. At that point, it started to symptoms right, well ... The set involved is an AWA model that before and any suggestion of a jitter, as though the bar was bouncing . ~ . .. . be ~ ~~ se:: a MAY 1992 43 • C4,Z 3.Cf 41,3 sov scv 3~ ~30_..u 040 ,.,_,z /2S0 /2SC20 66 o/2SC21 Fig.1: part of the vertical & horizontal output circuitry in the AWA SC5326. Transistors Q402 & Q403 form the vertical output stage & drive the vertical scan coils (at left) via capacitors C412 & C413. against some obstacle. And the further up the screen I forced it, the faster it jittered. At this point, I suddenly realised that I had been misleading myself. What I had imagined to be a fast roll was, in fact, a fast jitter. Of course, the difference was academic as far as the viewer was concerned but it was important diagnostically. In any case, I wasn't particularly worried. There isn't a great deal to suspect in this part of the circuit and I had already mentally cleared part of it anyway. Most of the circuitry is in IC401, which contains the sync separator, vertical oscillator, blanking circuit and the vertical drive. The latter comes out on pin 6 and goes to the vertical output pair, Q402 & Q403. These, in turn, drive the vertical scan coils. And it was everything from pin 6 to the scan coils that I had mentally cleared, on the simple basis that both the height and linearity, checked on a test pattern, were perfect. So was it the chip? I did a voltage check of all the pins and found nothing abnormal. I then checked the various minor components around the chip but again drew a blank. That threw suspicion on the chip and, since I had some in stock, it was easy enough to fit a new one. But, alas, still no joy. As far as I could see, that didn't leave anything else to check. It was 44 SILICON CHIP time to seek help. I rang one of the service technicians at AWA, described the symptoms and told him what I had already tried. He wasn't at all fazed by my story and immediately suggested two other components: capacitor C421 (220pF) across the scan coils and C588 (1000µF) across T573 in the pincushion circuit. He explained that both these components could give trouble and create symptoms similar to those I had described. So, full of hope, I changed both of them. But I drew another blank; it made absolutely no difference. And that really put the ball back in my court. I could hardly ask for more help; it was obvious that this was all that was known. But the advice had done some good. ... A CON\/G:t-.llli.N""i' AcCG:~':S ?DIN, FOR .,.-1-1e;. C. 'RO .. o It had broken through a mental barrier which had excluded anything in the output stage from my thoughts. If one component in this section could cause these symptoms, then why not another? And that brought me to capacitors C412 & C413 (330µF, 50V) in series between the output pair (Q402 & Q403) and the scan coils. I've often puzzled over this arrangement. Some models used only one capacitor, others the two-in-series arrangement (not back to back). Anyway, in desperation I pulled them both out and fitted two new ones. And bingo! That was it; everything was now back to normal. But the reason remains a mystery. I checked both capacitors on the capacitance meter and they both read full value. Nor did there appear to be any leakage, at least at the test voltage. Nevertheless, I suspect that leakage may be the answer - after all, what else can go wrong with an electrolytic? Or was one capacitor partially open circuit? And what was the reason for the two ·capacitors in series? Had leakage proved a problem in early versions, with only one capacitor, and had someone decided that two would reduce the risk? The reasoning, of course, would be that one could fail without creating a problem, while the chances of both failing would be quite small. SC 59.95 250.00 299.00 34.95 5.80 1.25 33.00 325.00 5.95 29.95 4.95 9.95 21% 28% 17% 20% 49% 20% 27% 17% 75% 33% 60% 60% YCAH f YCAH l \ CAI, c '((,Ail f YCAH 1::: YCAH f r l.,A h JAYCAR ,IAYC AR .AYCAR cAY CA R '' ' ' " ' KU Ntt.,;.::, ELEClRONICS F L, C TR OMCS FLEC lRONICS ELl:.ClRON IC:c, l..dl M CLCI..., 1 M Ul'W ..... V ,U"I t: L l:"l, 1 HU I\Jll., ::> JA Y L,AH tLt.L, I c,\q t Ll:.CIRONICS C,\R i LE CTRO NICS U,i1 E'LFCTl10NICS CAR ELECTRONICS CAr, l:.LrGi ' " ' :;Afl LU f l:. LEClROMCS t LECTRO NJCci FI EC1RONICS ELFCTRO NICS ::AH FLf-' :AR m, :A 11, LEr :,\R ELrr ~~;;: 3~~ ~AH , LlC ~AH , Lt· ~AH ELU ;AH ELEi ~:~ ~~~i :Ar, r LEc :AH H El :AH FU-c :;~ m~c :r,R E-Lf :'.;~ :~f '. ,AH f Lf l : .\R cLe ( :All LLEl ;AH flf l ;AR H ~ E conomy JAYCAR JAYCAR JA ,CAR JAY C AR t.Ll:.C 1HO NIC ~ JAY CA R ELECT ROl'<ICS J AYCA R FL,C TR ONI CS JAY CA R ELECT RONICS J ,\YCA l1 ELl:.CTRONICS JA Y L A H w·ire1ess secur1·1y . syst e m 1 ~~ 1~;;~~~ power supply WAS $249 ELECTRO NI CS ELEC TR ONICS ELi'C TRO NICS FLtCTRONICS f Ll:.Cl RONICS JA YC AR J AYC AR JA YC AR J AYC AR JAYC /1 R ELEC TRONICS ELEC TR O NICS FL EC TR ONICS ELEC TRONICS E'LFC lRON ICS J AYCA R J AY CAR JA, CAR JAYCAR ,IAYC Al1 EU ::Cl RONIC~ 1:. LEcCT RONICS H E' CT RO NICS ELECT RO NICS Fl 1·CT RONICS JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR YC Afl EC ,c Aii u: c YCA 11 F YCA R FC AR ELCC er YC AR i cA H 1:L: c 1CA R F / C AR , L: i c An cL: IC AH EL ;g;~n: SAVE $5 0 / CA R EL· / C AR 1:L, / C AR EL; ICA f1 EC 13V~~I) ~ 1 :W 1c;J<:J~ l:ID ITIO~§ UP TO DATE WORLD'STRANSISTORS , DIODES, THYRISTORS & ICS, COMPARISON TABLES. TWO VOLUMES. Vol 1 - A-Z Comparison tables of transistors, diodes, thyristors and IC's. Nearly 28,00 types with brief data, pin assignment. Over 80,000 comparison and equivalents. Excellent reference book, 967 pages, 110x150x 43(1hick)mm. CatBM-4580 $19.95 Vol 2 • IN-60 000-u Comparison tables a~d brief cfata and pin assignmenls of anolher 28,000 types of transistors, diode and !Cs of daily use. Over 80,000 comparisons and equivalents given. 950 pages, 110 x 150 x 42 (thick) mm. Cal BM-4582 $19.95 Teach Yourself DOS 3.3 & 4.0 ,n By Al Stevens. This remarkable how-lo Quickly cuts past computer mumbo jumbo of conventional documentation to reveal DOS's capabilities and power. Veteran author Al Stevens uses non-technical language to deliver indepth information on MS and PC DOS commands and operations. Teach yourself to set up fixed and floppy disk systems with easy-to-understand Instructions contained in this book. Arm yourself with real time saving techniques Including file maintenance and file protection. Improve your compuler's eltictency and effectiveness. Learn how to back up and archive files for safe storage. Master easy ways to handle tricky file directories. Improve your disk formatting and copying techniques. Experiences users will find comprehensive information on more advanced topics such as batch files and Edlin (the DOS editor). Maximised learning - overview of DOS for the new DOS user - DOS commands - Paths, fillers, pipes and input/output redirection batch files - EDLIN- Useful commercial utility programs - Index to general user needs - Glossary of commonly used terms. 267 pages, 153x224mm. CatBM-2475 u; FLFC The Encyclopedia of Electronic :~ t~~g Circui1s ,11 f-1 FC 111 l: LEC ,Fi ELfC ,R ELEC ,11 Cl[(, ,R 1: LEC .,RI' ~LL~~· ' ' ~0 ,H cLLC n ELEC R ELFC ~ ~~tg· R ELEC R I LLC R ELE'C ~ ~~~Z· :t~~g ~~~z :~ki ~ F Fe· ByRudolfFGrat. Thls bookhasa clrcullschemallcforjustabout everything you could think of lo build, nearly 1,300 in all. The are listed alphabetically and divided into 98 basic circuit categories. For example the sections starting with the letter A are: Alarms, Amateur All I radio, Amplifiers, A lo Dconverters, enua ors, Audio mixers, Audio oscillators, Audio power amps, Audio signal amps, Automotive. This Is the hobbyists and technicians dream treasury of both analog and digital circuits. From amateur radio and crossover networks lo fibreoptics, lest circuits, motor control, video circuits, times, etc, with special emphasis on slate-of-the-art IC circuit technology. Also included is a huge index to specific circuits. A massive 760 pages, size 17 23 WASSxS ELOLmlNmG. FOR $6 _ 9 95 . , , ,,.,..,,._,,. Cat BM-2476 Rf'ELLcCCI Hv ·1v R t:. I~ ,) R ELl:CIHON ICt-> 11 Elf CTHONIC" 11 [LEC Tn O NI C:i R r·L[ CTil ON ICS RF-! F-l-T R Ol\l lrc:. J1Y ' Arl \ L, ,A'oCAH I A \ CA R JA/C AR IAYC All $19.95 ~~/ t~-~~lt $34. 95 l+ ' ~ },F::3:,~; ~;~), t I t C JRUNICc,JAY'A C R I LFCTnO NI CS IAYCA l1 Lcf Cl llONICS .JA , CAR FL;cCTRONICS .1AYCAf1 [ Ll CT l10NIC,, ,I AYCAH I A Vrti. R i- 1 i=r TR /1"!/('C.. ~ ~~ ''j ;, blEC ' - ' , , ,v, ~,u~} rl f ClHON IC,, I I fC I RON ICS LLLC TR ONICS l:LEC TR ONICS I/\.V('fd 1 c· 1 ( ('TOf\ J\ll rl.: 1/\Vr ,\!J " ELI CTRONICS f Lf CTnON ICS H I Cl l10NIC:. 1·L,CT110NICc, ,Jt-, Yvr•J ~ FLEC TR ONICS JAYCAl1 fLFC JHON ICS JA, CAR LLI-C I HCJNICc, JAYCA l1 l Lf CT l lONIC:, ,J/1YCAH H f C I HUNIC,, l I L ,, f{ll --. 1\ 11/"C.: 1/,V('f\{J r I L(' I l)f'lt-dr'{_' ,m i v , ,11 1..LL\.., 1 n u,..,. rv.:i JA\CAR .JA , CAil ,IAYCAll JAY CAR E L; El; EL; EC: FC fl; U; ,cAn El: /CA R 1:i:: ICAR Fi! /CA R ICAR rCA R /CA R IC AR 'CAR •CAR 1 CAR ' CAR 'C AR ' CAR 'C AH ' CAR ' CAR ' CAR ' CAH ' CA R ' CAR 'CAR 'CAR 'CAR ' CA R (C AR 'C AR ' CAR 'C AR ' CAR ' CAR ' CAR ' C AR 'C AR 'C AR El! E~ El! f l! El! El; E0 EL; E0 FI, EG 1: G EG E~ E0 E0 E0 El; EL; E0 E0 E0 [0 E0 E0 E0 Ei: EL; E0 E0 E0 EL: ' CAR EL: 'C AR EL: 'CAR EL: :g:; ~ ~[. g~~ ~~: ~i•=.•u ~"""' ~·•.· .. · . . · . . ·'. 11!6i~llt"1111(1;.Ri!I ·cAR EL' CAR EL: g:~ ~ ~: •cAR EL' CAR CAR C AR 'CAR 'CAR 'CAR 'CAR EL' EL: EL: EL: EL' EL: EL: .....,_..,...,_~""'° :g:= ~t: -~~!111111..~ 'CAR EL: •cAR EL: ·cAR EL: 'CAR EG 'CAR EL: :g:= ~~ 'CAR EG 'CA R EL: :g~~i~ $19. 95 · 1 CA R t CA R ICAR ICAR /CA R 'CAR ICAH :g:= ~~ A huge data book listing dala for thousands of transistors, as well as alarge equivalent section. The book is designed for the engineer and technician. section 2 lists manufacturers names and addresses. section 3 is the huge alphanumeric listing of lransistors with specifications.. section 4 lists FETs with specs. section 5 covers injunction transistors. seclion 6 is the substitution guide. section 7 covers devices with prefix CV. section 8 lists 100's of transistor outline drawings and terminations.. 242 17 x 0mm. . ICAR H ; ICAH EL; ' CAR E0 Semicon's International Transistor Index Data and ■!11""·!11119'• Equivalen1s . 1_c :g~:~;~ CIVCU II T 1300~§ f-- c1: 1:. c ~~ ~~ ~ ~ YC An cc Four fabulous new books published by Micro Tech for Elektor Electronics. Each book has 300 circuits aimed at the electronic enthusiast, professional or s amateur. They offer a comprehension collection of practical ideas, concepts and developments, many of which have been in annual Eleklor magazines. You will find circuits for audio and video, car, cycle and motorcycle, home and garden, receivers and aerials, hobbies and games, measuring and testing, oscillators and generators, current sources and power supplies, microcomputer and music electronics and more. 300 Circuits cat BM-2470 $19.95 301 Circuits cat BM-2471 $19.95 302 Circuits Cat BM-2472 $19.95 303 Circuits Cat BM-2473 $19.95 To give you an example of these circuits - the 303 circuit book includes 32 audio and Hi Fi projects, 14 circuits for cars and bicycles, 43 computer and microprocessor circuits, 11 electronics projects, 24 HF and VHF circuits, 16 circuits for anumber of hobbies and pastimes, 54 projects for home and garden, 29 po.yer supply circuits, 29 circuits for test and measure men I equipment, 9 TV and video project, as well as 42 design Ideas F 1:. LE.CTRCX ELf- CTRO: ELECTRq ELEC TRO: ELEC TRO: LECTR O: YCAI< [I( -1c AH vc Ai , .. ·•"'•'")\] :.:.· El Ff f Li C f L[f. 1-LFC eLEC AH cl J AYC AR JAYCA R ,IA YCAR ,IAYCAH JAYCAH SELLOUT MAY PRICE $ 199 Al1 f, ,C AF· f-Lcl ·AR u er: AH H EL!:: CT HONICS ELEC TRONICS ELEC TRONICS ELECTRONICS ELECTRON ICS Install your own wireless burglar alarm and don't pay an arm and aleg! The EG100 is made by Zeus, the same people who make our current wireless system, in fact, all the same wireless extras will work with this panel. The EG100 is a key operated signal sector panel which accepts not only the wireless PIRs etc, but you can hard wire detectors as well. Eg 2 wireless PIRs, 2 wireless door/Window transmitters and a wired PIR will all work very happily on the one sector. This is the lowest prices wireless panel we've seen that is TOP QUALITY. There are plenty of junky ones around that we just won't sell. Aller all, aburglar alarm that false triggers is no good to anyone. FEATURES: • Low cost • DIY installation • Acceplswireless and wires sensors • Tamper proof protected JLED indicators • Keyswilch arming with exit delay time • Instant alarm when sensors triggered • NG and NO relay output. SPECIFICATIONS: • Operates on 303-875MHz • System codes 4,096 • Transmitting range 50 metres (open space) • 30 second exit delay • lnslant entry delay. ACCESSORIES: • Backup battery 1.2A 12V cat SB-2480 $26.50 • Wireless passive infra red detector Cat LA-5205 $129.95 • Door/Window reed switch Cal LA-521 O $69 • Siren 12V DC Cat LA-5700 $28.50 • Strobe tight Cat LA-5300 $32.95 • Wired PIRs from $49.95. ,AR F, FC Afl 1\H AR AH t,R JAYCAR JAYC AR JAYCAR JAYCA R JAYCA R · 'CARE~ JA\CAP LLEC f.YQ l,J iC,S J.!'l.'l'CA...9 E'....!:.C ~ t:: LEC\RO ~ JAYCA H ell CrRONICS JAYCAR EL[CmuNICS JA YCAH l: Lt C I HLlN ICS JA YCAn l'LFC TH OI JA\CAR cLFC rRO'J IC:i JAYCAR ELECTRONICS 1J AYC AR ELEC TRO NICS .JAYCA R ic LE:CTRm JA,CAll ELECTRON ICS JAYCAR f- LcC1RON ICS JAYCAR 1:Ll:CTl10NI CS JAYCAR ELECTRON JA\ CAii lLI Cl llUN IC" JAYCAH I LlC I HUN ICSl,JAYC1i R FLFCTRONI CS JAY CA R ELF crno, $,\\, r ' 11n L- 1 .:-r·Tnru,11rc 11\Vf" !I D C l { f"'T n ni.. If""~ 1/\V(' ,\Q J.. I 1-- ('T~/1 1\l lr<:..: lil.Yrll.P l=I r:rT P n ,.; :s J AYCAH EL~C THO NICS J AYC AR ELECTRONICS JAY CAR l::LECTRO NICS JAYC/\R ELE:CTHONICS JAYCAR ELl::CTRONICS JAY CAR ELECl RONICS JAY CAR ELECTRONICS JAY CAR ELECTRONICS JAYCAH f-1 :s JAYCA R ELEC TR ONICS JAYCAR ELECTRONICS JAYCAR ELECTRON ICS JAY CAR ELECTRON ICS JAYCAR ELECTRONICS JAY CAR ELECTRON ICS JAY CAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR f I :s JAYCAR ELECTRON ICS JAYCAR ELECTRONICS JAYCA R ELECTRON ICS JAY CAR fLECTHO'IICS JAYCAR l::LECTHO"<ICS JAY CAR ELEC-11ONICS JAYCAR ELFC I HONIG!:> JAY CAR f-LlcCl HONICS JAYCAR l :s JAYCAR LECTRONICS JAYCAR ELECTRONICS JAYCAR EL:cCFlONICS JAYCAR ELEC -ROI\ICS JAY CAR ELECTRO ICS JAYCAR ELFCTRO'IICS IAYCAR FLFClRONICS JAYCAR El FCTRONICS JAYCAR El :s JAYCAR ELECTRONICS JAYCAR ELECTROt-.lCS JAYCAR ELECTRO'IICS JAYCAR EL[CTRONICS JAYCAR EcFCTROt-.lCS JAYCAR FcECTRO:-.ICS JA>CAR ELFCTRO'IICS JAYCAR ELEC-RONICS JAYCAR 1::1 :s J AYCAR ELECTRO ''1 CS JAYCAR ELECTRONICS JAYCAR ELECF1O'JICS J AYCA l1 EL:cC TR ONICS JAYCAR EclCTRONICS JA\'CA fl ::s JAyr,110 c: , c:rTor.J\ur-<:: 1Avr11n c:1 c:rTorH,.1r<:: 1l1Vf'Ao i::1 :::rn~n-..ur-c: 1r. vrr.A , Ll CJ RONICS JAY CAR I Lt C' RO'J ICS JAYCAR I Ll CTnONIC::i JAY CAR El c: c:rTAf"\l\11 rc:.: u1.·v'r!l.A r:- c:rTR()'-.Ji"C, lA'vr'AA ;::1 i=r T Ar'IJ\dr'C:.. 111'-r"tiA F=t 1=r1nnr-.11rc, IAYr.A R FI l=(:TR()N IC'S ,JAYCAR E! ;TRON I ;;~g~ ;TRON ,rnoN :;::g: JAYCA ll [ I ARE YOU SICK AND TIRED OF PAYING TOO MUCH FOR BATTERIES? "'' , • we ceRTAINLYweRe. so wevrnoN'T soMeTHINGAsourn White TV Coax Sale - ·::~g:: ~: 30mt Rolls IAYCAR FI IAYCAR El am'"" '"""' ..,,, .., "'""""" '°"' =! w,sent """' black _, and ourrosuppliers us :TRON :TRON w, "'"' lolrodoces arao~ """"'"'· oe>lly "'"" n., is good and when you compare !he value our rechargeable NiCad batteries, Vinnick so you know the quality you'll be pleasanlly surprised. There are lwo ranges available: Long life general purpose and Gold Extra Heavy Duty Zinc Chloride. while coax. 3C2Vstyle in convenient 30ml rolls. Meter :TRON Long Life 30mt roll price normally $1 4.95. :TRON :~=g~ rno'l AA TRo'I c ,TRON D 9V ;:g~ ~~g~ Pkt 4 Pkt 2 Pkt 2 Pkt 2 $1 .60 :~~t $1 $2.25 cat SB-2330 cat SB-2331 Cal SB-2332 Cat SB-2333 ;~g~ Gold Extra Heavy Duty Zinc Chloride TAO, AAA ;:g~ TRO '. Tr1ON lRON Tl1O N TRON THOI'. TRON 'Tf1O'-i l RO '. lRO'. TRO'I TRON TRON TRON TRON TRON Cat SB-2340 Cat SB-2341 AA Cat SB-2342 C Cat SB-2343 D Cat SB-2344 9V Discharge rates for Gold Extra Pkt4 Pkt 2 Pkt 2 Pkt2 Pkt 1 $2.50 $2.75 $2.75 $3.25 $1.75 Heavy Duty Size Norn AM 1.5V AA 1.5V 1.5V C 1.5V D Cutoff 0.85V 0.75V 0.75V 0.75V Load 15 ohms 4ohms 4ohms 4 ohms Mins of service 280mins 190 mlns 480 mlns 910 mlns i· j_] :::g;; ;: 1,,cA11 El Jaycar wil I purchase your surplus stocks of ~~~WB~~gg M • $i O 95 S $ ay price · ave 3 112 That's only 36 ~ per meter U\!l~ AUDIO LEADS 3.5 stereo plug to 2 x RCA plug. 1 .2mt long . $4. 95 (02) 743 5222 $4.50 .______ii' Cat WA- 1024 ~EUt !~~ICON~,UCT&RS 4060 14 stg count.div +oscil ZC-4060 LM358 Dual op amp ZL-3358 IBODv ~<at> ~;~g~~ components and equipment. We are continually on the lookout for sources of prime quality merchand ise. Call Mark Harris or Bruce Routley now 3.5 stereo plug lo 3.5 stereo plug. 1.2ml long. catwA-1022 !AYCAR 1:1 AYCAR F 1 $1 .95 $1.20 LESS 10°/a !: sAYCAR, 1 1AvcA<1 ! 1 ~~:g;~ ~ JAYCAH I ::~c:~ ~ I J!~,-1 GAH f .11\YCAR fc IA'1CAR E ~YCAR L iAYCAH t 1A~CAH L .AVCf\R F. ·AYCAR f ,·AYC/'...H f,AYCAR f1AYCA H t AYCAH, .AYCAH f' 1Ar'C1\R AYCAH .•A\C/\R AYCAI< ,\YCAH " /\YCAR 1AYCAf1 'A\CAl1 f I F I 1:. f E I I PRODUCT SHOWCASE] Scope programmable alarm has six sectors This is a professionally designed and built alarm panel with six sectors and highly flexible programming, via the 12 button keyboard. As many as 51 separate facilities can be programmed but if you just want of use it as a standard 6-sector alarm, no programming is required. Two manuals are supplied with the unit: a basic instruction manual and a 114 page installation & service manual which has all the details of programming. Inside the case there is plenty or room for wiring and a standby battery. The complete system, less mains plugpack and standby battery, retails for $199.50. Or you can purchase just the printed circuit board, if you want to mount it remotely. In that case the PC board costs $129.50 plus $49.95 for the intelligent remote keypad and 7-segment display. For further information, contact your closest Jaycar Electronics store or phone them on (02) 743 5222. Handy magnifier for PC board inspection Do you have trouble inspecting your solder joints on printed circuit boards. This handy magnifier makes the job much easier, whether or not you normally wear glasses. The magnifying lens is 115mm in diameter and its In-circuit fault finder The new T1500 from Polar Instruments is specifically designed for troubleshooting unpowered PC boards. It will test any kind of component, including linear or digita'l. LCs, tFansformers, relays, discrete transistors and capacitors. To test a suspect component, a pair of probes is placed across it. This applies a small AC voltage across the component and the Lissajous pattern resulting from plotting voltage and current is displayed on the screen. This can be compared with the normal pattern for the component (Polar calls it the "dynamic signature" of the component) which can then be accepted or rejected. The T1500 has four ranges and two test frequencies to cope with a wide variety of components. By using the dual channel comparison technique, users can identify if the component is good or faulty. This allows operators with lim- ited technical ability or poor documentation to locate faults to component level. For more information, contact Mark Breznik, Emona Instruments, 86 Parramatta Road, Camperdown, NSW 2050. Phone (02) 550 1378. MAY 1992 53 cleaner removes dirt from keyboards, monitors, printers and PC boards. Several attachments are included. 5.25-inch and 3.5-inch cleaning discs (wet type) are provided for removing dirt from read/write heads in drives. For more information, contact Rod Irving Electronics at their Stanmore or Melbourne stores. Protect your valuable issues Silicon Chip Binders New catalog of HP power supplies fold-up stand makes it quite convenient to work with. Use it in conjunction with a desk lamp for even more ease of use. It is priced at just 13.95 from David Reid Electronics, 12 7 York Street, Sydney 2000. Phone (02) 267 1385. These beautifully-made binders will protect your copies of SILICON CHIP. They feature heavy-board covers & are made from a distinctive 2-tone green vinyl. They hold upto 14 issues& will look great on your bookshelf. Clean-up kit for computers * High quality * Hold up to 14 issues * 80mm internal width * SILICON CHIP logo printed in gold-coloured lettering on spine & cover Price: $A11.95 plus $3 p&p each (NZ $6 p&p). Send your order to: SIiicon Chip Publications PO Box 139 Collaroy Beach 2097 Or fax (02) 979 6503; or ring (02) 979 5644 & quote your credit card number. Use this handy form l ----------Enclosed is my cheque/money order for $_ _ _ or please debit my □ Bankcard □ Visa □ Mastercard Card No: Card Expiry Date _ _/_ _ Signature _ _ _ _ _ _ _ __ Name _ _ _ _ _ _ _ _ __ I I I I I I I I I I I I I .___________ . Address _ _ _ _ _ _ _ _ __ _ _ _ _ _ _ _ P/code._ __ 54 SILICON CHIP Surprising as it may seem, your computer constantly acts as a vacuum cleaner, drawing in dust particles via the cooling fan. This dirt then settles on the drives, discs and boards. This cleaning kit from Rod Irving Electronics addresses the dirt problem. The kit has everything to clean your machine inside and out. Doubleended cleaning wands reach into crevices and antistatic cleaning pads remove dust and help in keeping it away. The battery operated mini vacuum Hewlett Packard has just released a new catalog of their DC power supplies and electronic loads. An introductory section outlines important aspects in selecting a supply for specific applications and a quick reference to the line of DC supplies is also included. Among the programmable supplies in HP's range are single and multiple output units and a mainframe with interchangeable modules. Programmable electronic loads are offered as single input models or as modules for use in the mainframe. For more information, contact the Customer Information Centre, Test & Measurement, Hewlett Packard Australia Ltd, 31-41 Joseph Street, Blackburn, Vic 3130. Phone (008) 033 821. .,.s~.,.i;;i:.i;~ RCS Radio Pty Ltd is the only company which manufactures and sells every PCB [, front panel published in SILICON CHIP, ETI and EA. 651 Forest Road, Bexley, NSW 2207. Phone (02) 587 3491. Electronics Workbench® The electronics lab in a computer! MH series amplifier (left) & PSU1 piggy back supply unit. New masthead amplifiers & splitters from Hill Industries There are five models in this new range of MH series masthead amplifiers from Hills. The units are designed to cover a wide variety of applications in both the UHF and VHF frequency bands. All amplifiers have a filter which rejects FM (band 11) signals. If the unit is required to amplify FM signals as well, the filter is rendered inoperative by cutting a link. Each MH series masthead amplifier consists of two units. The amplifier itself is installed on the antenna mast and is housed in a black weatherproof box. A U-clamp arid wing nuts secure it in place while the power supply comes in the form of a plugpack which can be 'piggy backed' with the TV's power plug (see photo). Thus, both the TV ' and the masthead amplifier The Extraset 1-4 amplified are powered from the same splitter. socket. The power supply unit sends the amplified signal to the TV via coaxial cable. It also has provision to supply signal to a second TV. If you need more TV or FM outlets, the Hills range of Extraset amplified splitters could be answer. There are two models. Extraset 1-4 is a self contained mains-powered unit for use in locations with ready access to 240VAC. The other, Extraset 4LP, is a line-powered 2-part unit consisting of the amplifier and a 'piggy back' power supply for use where access to 240VAC is more difficult. Both units have a single antenna input and four outputs for TV or FM radio use. Both the masthead amplifiers and the amplified splitters can be easily installed. For more information, contact Hills Industries, 944-956 South Road, Edwardstown, SA 5039. Phone (08) 297 3888. New transistor mounting washers This new range of transistor mounting washers allows you to dispense with that messy process of applying heatsink compound. Why didn't somebody think of it before? They have a high voltage rating and come in the common sizes - TO-220, TO-3, TO-3P and so on. They are available at all Jaycar stores. C> 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, THREE VERSIONS • Professional Version : EGNVGA colour display; unlimited components • Personal Plus Version: Monochrome display ; unlimited components • ·Personal Version: Monochrome display; limited to 20 components per circuit 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 EMONA INSTRUMENTS NSW ......................... (02) 519 3933 VIC ........ .. .......... ........ (03) 889 0427 OLD :......................... (07) 397 7427 DISTRIBUTORS Perth .. ... ... ... .... ...... ......... (09) 244 2777 Adelaide .................. .. . (08) 362 7548 Hobart .. .................... .. .. . (002) 34 2233 EmonaLAB4 Four instruments in one package! The LAB4 has four full function test instruments : ■ DC POWER SU PPL V Triple output; 5V, 15V, 0-S0V ■ 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. DIGIT AL MULTI METER Full function, auto-ranging ■ FUNCTION GENERATOR 0.02Hz-2 M:-iz , 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 EMO NA INSTR UMENTS NSW ...... .. ............ ..... (02) 519 3933 VIC ... ........ ... .............. (03) 889 0427 OLD .......................... (07) 397 7427 DISTRIBUTORS Perth ... .... .... ..... .. .. .. ...... (09) 244 2777 Adelaide ..... .. ............... .. (08) 362 7548 Hobart ............. ............. . (002) 34 2233 MAY 1992 55 Balanced line receiver for audio applications sional and automotive audio equipment, as well as industrial applications. For more information, contact Ian Laidlaw at NSD Australia, 205 Middleborough Road, Box Hill, Vic 3128. Phone (03) 890 0970. tronics, 127 York St, Sydney 2000. Phone (02) 267 1385. Micro drivers for teensy weensy screws Engrave your valuables with the Easy Etch The SSM-2143 from Analog Devices is a balanced line receiver system for audio and industrial applications requiring high immunity from electromagnetic interference (EMI). It has a differential gain of0.5 and has a common-mode rejection at 60Hz of -90dB and -85dB at 20kHz. Housed in either an 8-pin mini-DIP or SOIC package, the device complements the SSM-2142 balanced line driver. Together, they provide a high performance solution to driving and receiving audio signals over long cable runs in noisy environments. Two gain options (2 or 0.5) make it flexible for use in consumer, profes- With the ever-present risk of theft, it's a good idea to engrave your household valuables with your driver's licence number. This is only one of the possible uses of the Easy Etch Engraver. It has a steel bit and is suitable for engraving metal, plastic and wood. Replacement bits are available. The unit is powered by a 12V plugpack and retails for $34.95. For more details, contact David Reid Elec- PRESTON ELECTRONICS 217 High Street, Preston, Melbourne Victoria 3072 (Cnr of Bell & High Street) Quantum 50-Meg SCSI Hard Drive (1 only) $295.00 Fujitsu 240V Coil Relays, DPDT 30A $9.95 ea Fujitsu 5V Relays, SPOT Subminiature 2764 Surplus Computer EPROMs, Erasable $19.95 $3.95 27128 Surplus Computer EPROMs, Erasable $4.95 27256 Surplus Computer EPROMs, Erasable $5.95 27512 Surplus Computer EPROMs, Erasable $6.95 QC-191 O Super Tiger 5MHz Oscilloscope $29.95 TEEPROM EPROM Writer Card/Cable + Software To Suit IBM-Compatible Computers $39.95 ff Mail Order Hot-Line 8/Card-Mast/Card-Visa heque Phone (03) 484 0191 56 SILICON CHIP Most enthusiasts probably have a set of jewellers screwdrivers which let them do work on most miniature equipment but this set of drivers is for really tiny screws that the standard types are too big for. There are seven drivers in all with tip sizes of0.6, 0.7, 0.8, 1.0, 1.2, 1.4 and 1.6mm. They would be particularly handy if you are working on tiny brass model locomotives or their equally tiny motors and gearboxes. The set of dr.ivers is available from Rod Irving Electronics at their Sydney or Melbourne stores. PCB faults & shorts locator from Emona Instruments The Polar 850 shorts locat!Sr allows you to pinpoint short circuits on PC boards in a fraction of the time it normally takes. By locating solder bridges, etching defects, faulty ICs or faulty decoupling capacitors, the 850 also eliminates the need to cut tracks to isolate the fault. Three different techniques are employed to track down short circuits. 2MQ, 40MQ and 200MQ ranges allow shorts to be located between PC tracks or component legs by finding the point of minimum resistance. For higher resistance faults, a 2mV range with lµV resolution allows the tracing of current flow along tracks. Finally, a magnetic field sensing current probe traces current along inaccessible paths such as through ICs or through buried tracks in multi-layer PC boards. A variable pitch tone and a digital display are used to guide the user to the shorted location. For more information, contact Mark Breznik at Emona Instruments, 86 Parramatta Rd, Camperdown, NSW 2050. Phone (02) 519 .3933. SC VISIBLE LASER DIODE HEAD JmW GAS LASER SOLAR PANEL GIVEAWAY Sui t teachers. doctors, bus inessmen, and other professionals. Improve an d enhan ce all you r presentations. Not a kit. but a complete commercial pen sized laser poi nter at an inc redible in troducto ry price ! $199 ON LY Small pen sized body. Ru ns on two sma ll AAA b atte ry. Batte ry life : 2-10 hours. Vi sible 5mW red (670nM) laser. Proj ects a Brand New high quality US made, amophourous glass Solar Panels. Dim ensions: 150 X 150 X 2.5mm . In normal sunlig ht they deliver a full 1 Watt whilst charging 6V-8V batteries! Can be co nnected in ser ies, in parallel. or series I parallel, to inc rease the vo lta ge, and/or cu rrent capacity. For example, in average sunlight , two of these panels connected in se ries will deliver approximately 150mA of charging current , into a floating 12V (14V) battery: 2 Watts' Four panels can be connected in seri es paralle l to deliver 300mA into a float ing battery : 4 Wat ts ' Comp are the prices ' All the panels . have a weat her INCREDIBLE PRICING: protection film on rear, and the terminat ing clips are provided. ea. or 10 fo r $75 s9 than 50 metres. As used for medical treatm ent by so me doc tors and acu punctu rists. . •• ., ,:.,. ·~ A high q uality laser beam di verging (beam expander) glass lens, mounted on an alum ini um plate, with mounti ng screws provided. Dimensions: 25 X 25 X 6mm. Use it to ex pand the laser be am fo r Holog raphy, Special Effects, or one of th e two Small black anodised metal body. Removable pressure switch. Vertical and horizontal adju stments. Batte ry li fe more than 10 hours continuous . 5mW 670nM cl ass III A laser. Range is about 150m, some wou ld claim three ti mes more. Shock teste d to 20009 . One year warranty. ON LY s9,9Q SILICON SOLAR CELLS ~m11int~ High efficiency silicon ce ll s. With normal su nlight. and under load . ea ch on e of these 12.5 X 50m m ce ll s wil! de live r 0.46V at approximately 175mA: V o/c = 0.58V, I sic = 188mA. Glass from a ve ry small picture frame, an d some silico n coul d be used to make a 6V / 1. 1W (14 ce ll s) or a t 2V / 2.2W (28 cells) solar pan el! Pretinned co nnec ting solder co nnect ions are provided. ON LY 5 1 ea. EXPERIMENTAL ·. E.H.T. POWER SUPPLY ,· s299 Price includes one rifle or pistol mount 135 ARGON LASER 99 A very small telescopic monocular IA viewer. Actually 1 h of the IA Binocular Vi ewer,•.~};iiii~ advertised els ewhere in this advertisement. Very small: Length of scope is 130mm without the rubber hood fitted . The assembled scope has high quality military grade optics, and employs a prefocussed IA image converter tube. This tube has a useful response from 600-1300 nM , thus also making it useful when working with IA LEDs, and JR laser systems. The scope has provision for a coaxial E. H .T. connect ion, and is su pplied with a power supply k it, t hat features a ready assembled inverter on a sma ll PCB. The power supply easi ly fits into a small plastic case, and can be fitted with a belt r::fc1i~~s~i5i~;';'!i:1d~a1~:! ~;;;,~~tbo s239 MAINS OPERATED LASER lenses requi red to fine focus a laser be am, for Su rveying and Bar Code Reading . s NIGHT VIEWER BARGAIN visible red spot at more DIVERGING LENS Includes high quality low divergen ce Siemens lase r head with an output at about 3mW an d one of our reliab le and effic ient 12V un iversal laser power supply kits. The tube is used but it is guaranteed. The kit co mes with full instru ctions and it even includes a prewou nd transformer. The applications include high power laser poin ters, surveyi ng equipment, optical ex periments, educatio n, holography, medical field , disco s displays, etc. ONLY Save. by mak in g your own laser poin ter. las er gu n sight. medical treatm ent laser. etc. Produces a well collimated beam . Designed to be powered directl y from a 3V batte ry. or from hig her voltages. if a simpl e co nsta nt sou rce is added. Simple circui t included . 5mW (670nM) . At an incredible introductory pri ce of : For th e head only: Add $8 for the .ex tra "bits" needed to make a complete laser diode pointer. Case, switch, alkaline batteri es, and battery holders. Eve rything yo u need to make a complete, self con tained, visible ·Iaser poin ter or gunsight. Con sider thi s Mains Powered Lase r Bargain , for discos, laboratories. photography, holography, medical field, etc. Supplied with two 3mW Sei me ns tubes. and a brand new potted mains laser power supply. Th~ :~,~~~ 3 5 189 f~=~~~i!Yu~~e iu~~~~\~;~tfe We can also supply the mains lase r supplies wi th lower powered tube. at a slightly lower cost. Ring or fax . KIT SPECIALS INFRA RED FILTER LCD DISPLAY MODULE These are brand new 16 character by 2 line mod ules (16 X 2). has back lightmg prov ision High quality. high contrast. alphanumeric LCD display modu les. with surface mounted control c irc uit ry already moun ted underneath the PCB. Require a few m1llamperes at 5V to operate. We include infor mation . ON SPECIAL AT s1s LENS ASSEMBLY This plastic len s assembly includes a lens with an ap!Noximate diam eter of 12m m. whos e focal point is about 1h th e length of the cylindrical tube. which is 20mm long. Moun ting holes provided . Great for housin g an d imp roving th e sensit ivity of any ~i~~c~~~s.laser These air cooled Argon Laser Heads have had re lati vely " low hours" of operation . They are guaranteed . They produce a bright blue beam (488nM) and have a power ou tp ut in the 10-100mW ra nge. Lim ited supp lies. at a small fraction of the ir real value. ssoo ONLY T he head includes powe r meter ci rcui try an d starting circuitry. Circuit diagram provided. Also provid ed is a circ;:uit for a sim ple power supply. We can prov ide th e maj or compon ents for this s upply. En quire. ea. s5.50 /?1~ ,· '$. t' . High qual ity military binocular IA viewer. Self powered. and ori ginall y intended to be moun ted on a helmet. Foc us Is adJustable from 1 metre to infinity. Requires some IA illum ination . Powered by one single 1.5V battery. Ori ginal fibreglass carry ~f~~td s~~dce/. s549 0 IR LASERS A high quality. milita ry grade. deep infra red (IR) filter. For medium and high power incadescent spotlights and flood lights. Approximately 130mm diameter and 6mm th ic k. High temperature pyrexglass base material. Excellent for night surveillance equipment! Works wlth IR viewers and so me video eg'/tfPeE~ IA L AT s55 This preci si on coll imator assembly was removed from work ing laser printers. bu t is supplied wi th an extra Brand New laser diode to sur t. It produ ces a be am that can be focussed to a fin e dot or hne Barel y vIs1b le. 780 nM/SmW. We also supply a PCB components and instructions kit. for a suitable digit al driver circ uit that can be used to complete the la se r transmitter Suitable for commun ications. data lin ks. perimeter e;;:~~~os~oi::. code reading. medical . etc . s59 LASERS are not for kids: DANGER Melbou rn e Distributor : Electronics World (03) 723 3860 or (03) 723 3094 ULTRASONIC CAR ALARM Crystal locked ult rasonic movement detector and/or a self stand ing ca r alarm. Provision for bonnet/boot protection and battery back up. See S.C. May '88. The kit includes the PCB and com ponen ts. the ultrasonic tran sducers. but the screw terminals are not provided. CLEAR AN CE AT $24.90 THE MICROPHONE This un it has a bu ilt in preamplifier so it can drive any amplifier. Turn your stereo amplifier into a PA amplifi er. Also features to uch switch ing , battery c heck fun cti on. etc. See EA Nov. '86. CLE ARANCE AT 5 19.90 MAY 1992 57 Build this telephone intercont Do you have a couple of old telephones sitting in your junkbox? This simple project will turn them into a useful intercom unit that works just like a real telephone system. By GREIG SHERIDAN Ever wondered how Commissioner Gordon managed to raise Batman so effortlessly on the hotline? Or have you ever been curious to know how the White House-Kremlin hotline works? Both systems are probably very similar in concept to this telephone intercom - ordinary telephones connected to 2-wire lines and featuring full-duplex operation (ie, simultane58 SILICON CHIP ous 2-way conversation). As well, this unit is simple to drive, easy to build and doesn't cost the earth! As well as an intercom, this interface is capable of testing telephones, modems, DTMF decoders and facsimile and answering machines. It is also ideal for theatrical applications. A stripped-down version could also be used to make role-playing training sessions more realistic at telephone counselling services. In fact, this is the purpose for which the circuit was initially designed. Telephones - an introduction A telephone in its on-hook (hung up) state exhibits a capacitance and series resistance between both legs of the line. This is the ringing circuit see Fig.1. An AC ringing signal will pass and cause the bells to ring or the "tone ringer" to warble. When the phone is taken off-hook, a DC loop (mainly resistive) is applied to the line and DC flows, fed from the exchange. The exchange equipment detects this current flow and either stops the ringing signal (for an incoming call) or sends dial tone (if it's an outgoing call attempt). When a phone is rung, the ringing signal is connected to one leg of the line and the return path is through and frequency are not critical. For applications where a higher ring voltage is required (generally the 800 series phones and their Bakelite predecessors), a larger ring transformer can be used. As well as the Arlec 75XXX and Know how 7VA transformers, the circuit board has been designed to accept the Farnell T 150-07X 6VA series. The I I Farnell 24-0-24 (150-076) rings ..J.. RL1 RL2 an 800 series telephone much more convincingly. For those who want to go L - - - - - - - - - - - 4 - - S~P~Y over the top, replace the power Fig.1: the basic telephone ringing circuit. supply shown here with an When one phone is taken off-hook, the ring ex-Telecom 50V supply (comrelays in the other loop close & a ringing plete with 75V ring). These signal is applied to the second phone. supplies occasionally pop up at electronics disposals stores the DC supply. The idle line voltage is for a fraction of their "new" value. usually around 48V, although this is To operate the intercom, you simnot critical. ply lift one phone and the other phone When the phone handset is off- rings. Lifting the second phone then hook, a current of 20-30mA flows. stops the ringing and conversation This is sufficient to power the phone's can commence. transmitter (microphone) , whether it The circuit does not reset until both is a modern electronic type with an telephone handsets are replaced. This in-built preamplifier or the original prevents the first phone to be hung up carbon granule type. from ringing until the second phone This loop current also powers any "clears". It also allows one party to dialling circuitry where appropriate. hang up and continue the conversaThis circuit emulates the above con- tion on another extension on the line. ditions, which makes it compatible Circuit details with just about all types of telephone. However, there are a couple of deviaFig.2 shows the full circuit details. tions from standard telephone prac- All the required voltages are derived tice. from two power transformers. One First, the circuit described here uses transformer (Tl) provides a +12V rail a negative earth whereas telecommu- (via D5 and a 3-terminal regulator) for nications equipment generally runs the logic and around 46V DC for the on a positive earth. This convention telephone "speech" voltage. The secwas chosen to minimise electrolytic ond transformer (T2) produces around action in earth stakes and the like but 90V peak-to-peak (nominally 30V as this is not applicable here, it has RMS) for the ring signal. been omitted. Besides, I hate trying to The whole circuit uses only four think and design for a positive earth. CMOS chips and two optoisolators to The ring voltage and frequency have provide the logic and generate the also been altered to keep the project required ringing signal. Let's see how easy to build and the cost as low as it works. Schmitt inverter stages ICla & IClb possible. The normal exchange ring signal is 75-90V RMS at 25Hz but, by provide buffering and false triggering experimentation, it has been found protection for phone 1. In the idle that this voltage and frequency are state, there is no DC flowing in the only required when driving older tele- phone line and so the LED in the phones with real bells. associated optoisolator (IC5) is off. Modern telephones usually rectify ICla's input is thus held high, which the incoming ring signal and regulate means that pin 12 ofIClb is also high. it to about 12V, which then becomes Similarly, if phone 2 is on-hook, the power supply for the ringer chip . pin 10 of ICld will be high. These So, for these phones, the ring voltage logic highs are fed to pins 5 & 6 of PARTS LIST 1 metal case, 256 x 155 x 76mm (W x D x H) 1 PC board, code SC12105921, 132 x 102mm 1 PC board, code SC12105922, 105 x 103mm 1 mains cord & 3-pin plug 2 15-0-15V 7VA PC-mounting transformers (see note 1) 1 600:600 ohm transformer (Arlec 45035, Altronics M1000, Jaycar MA-1510). 2 12V DPDT relays (Jaycar SY4061 or Altronics S-4165) 2 LED bezels 1 4-way screw terminal panel 1 100kO 10mm horizontal trim pot 19 PC stakes 1 cordgrip grommet 1 solder lug Semiconductors 1 74C14/40106 hex Schmitt inverter (IC1) 1 4081 B quad AND gate (IC2) 1 4001 B quad NOR gate (IC3) 1 4017B decade counter (IC4) 2 4N25 optoisolators (IC5,IC6) 4 BC547 NPN transistors (01 ,02,03,05) 1 BC557 PNP transistor (04) 7 1N4004 diodes (D1-D7) 4 1N914/1 N4148 diodes (D8D11) 2 3.3V 1W zener diodes (ZD1, ZD2) 1 5mm green LED (LED 1) 1 5mm orange LED (LED 2) Capacitors 1 3300µF 63V PC electrolytic 1 1000µF 35V PC electrolytic 2 10µF 25V PC electrolytic 3 1µF 25V PC electrolytic Resistors (0.5W, 1%) 3 100kO 2 6800 2 47kO 3 2200 6 10kO 2 1500 21.2kO1W Miscellaneous Machine screws, nuts & washers; hook-up wire; two telephones; 2way telephone cable. Note 1 : if a higher ring voltage is required, use a 24-0-24V transformer (eg, Farnell 150-076) for the ring supply instead of one of the specified 15-0-15V transformers. MAY1992 59 + 1 2 V • - - - - - - - - - - - - + - - - - - - - - -....- - - - - - - - . . - - - ~ - - - , RING 202 3.3V PHONE 2 100k 15 R .,. +12V 16 D10 VR1 100k IC4 4017 Q3 BC547 37 240VAC ":' 3300 63VW 14 + 1000l25VW+ T2 15V-0-15V OR 24V-0-24V D5 +12v---------- 8 rO.c 1N4004 VIEWED FROM BELOW TELEPHONE INTERCOM Fig.2: the final circuit uses optoisolators IC5 & IC6 to isolate the ring circuits from the control logic. When one phone is taken off-hook, then either Ql or Q2 turns on to activate the ring relay in the other circuit. Transformer T2 provides the ring signal, while IC4 & its associated parts generate the ring sequence. AND gate ICZa, to pins 5 & 6 of NOR gate IC3a, to pin 13 ofIC2c, and to pin 8 ofIC2d. Assuming that both phones are initially idle (ie, on-hook), the output of ICZa will also be high. This holds the RS flipflop formed by IC3b & IC3c in its reset state, with "Q" low & "Q-bar" high. The Set input of the RS flipflop 60 SILICON CHIP (pin 13 of IC3c) is fed from pin 4 of IC3a which is currently at logic 0. If phone 1 is taken off-hook, current flows through the LED in optoisolator IC5 and turns on the internal transistor. This pulls pin 1 of ICla low and thus the previous high on the reset of the flipflop is also toggled low (via IClb & ICZa), which means that the flipflop can now be toggled. Similarly, if phone 2 is taken offhook, pin 3 of IClc goes low and toggle~ the Reset of the flipflop low via ICld & ICZa. IC3d detects any difference between the states of the two phones. When a difference is detected (ie, when one phone is taken off-hook), its output at pin 3 goes high and turns on LED 1 via transistor Q5 (actually, ICZa, IC3a & IC3d together form an XOR gate to detect the different phone states). TABLE 1 Symptom Possible Fault No sidetone in either phone Is green "power-on" LED lit? Check all voltages. If either + 12V or +46V rail missing, switch off & di$COnnect the logic PC board from the supply. Power up & check the supply rails again. If supply rail(s) still missing, check the supply board; if supply rai ls now correct, check for a snort on the logic board. No sidetone in one phone only (1 ). Check that the associated 220-ohm protection resistor in the loop circuit has not burnt out. (2) . Do cabling & telephone test OK? Check by swapping phone lines over on the back of the interface. If the same phone still has no sidetone, then the fault is either in the phone itself or in the cable. No ring to either phone (1 ). Check that the 220-ohm ring protect resistor (connected to transformer T2) has not burnt out due to excessive current. Check the loop circuitry carefully before replacing this resistor. (2). Are interrupted ring counter IC4 & transistor 03 operating? Test by earthing collector of 03. (3). Check that the orange LED (LED 2) is off when both phones are on-hook. If LED is on & logic circuitry is OK, then one phone is faulty or there is a cabling fault. Test this by removing the wires from the interface. No ring to one phone (1 ). Check ring supply voltage from transformer T2. (2) . Is associated ring relay (RLY1 or RLY2) operating? If phone 1 does not ring, check for high on pin 11 of IC2c. If pin 11 high, suspect switching transistor 01 & RLY1. If phone 2 does not ring, check for high on pin 1O of IC2d. If pin 1O high, suspect 02 & RLY2. In addition, when IC3d's output goes high, pin 3 of IC2b also goes high. Depending on which phone was taken off-hook, then pin 11 of IC2c or pin 10 ofIC2d will switch high. (Note: IC2 is a 4081 quad 2-input AND gate. When both inputs of these AND gates are high, the gate output will be high). Let's assume that phone 1 has been taken off-hook. In this case, pin 10 of IC2d switches high and forward biases Q2. Q2 then subsequently turns on and activates ring relay RLY2 whenever Q3 in the ring circuit turns on. Similarly, if phone 2 is taken offhook first , pin 11 of IC2c switches high and forward biases Ql. In other words, taking phone 1 offhook closes RLY2 and rings the bell on the other phone. And vice versa. the beginning the ringing cycle, rather than having to wait for possibly up to two seconds for the ringing cycle to begin. IC4 is clocked by Schmitt oscillator stage IClf and turns on Q3 and ring relay RLY2 each time its "1" and "3" outputs go high. It also switches interrupt transistor Q3 (via its "2" output) to generate the required ring cadence. The exact operation of the ring cadence generator is described a little further on. Each time RLY2 operates, its contacts close and the AC ring signal from transformer T2 flows through phone 2, ZD2, the series 1.2kQ and 220Q resistors, and the 3300µF filter capacitor on the +48V supply rail. If the calling phone now goes back on-hook, pin 3 ofIC3d goes low again Ring circuit and the circuit reverts to the idle conCounter stage IC4 (4017) and its · dition. Alternatively, if the called party associated parts form the ring timer answers, pin 4 of IC3a goes high and circuit. It is normally held reset by toggles the flipflop (IC3b & IC3c). This ICle but is activated when pin 3 of sets Q-bar of the flipflop (pin 11 of IC2b goes high and pin 8 of ICle IC3c) low, which in turn switches pin switches low. This ensures that the 3 of IC2b low and stops the ring. Conversation can now proceed, counter is only one "clock tick" off g QUALITY NO BRAND DISKETTES 5.25" 5.25" 3.5" 3.5" DSDD DSHD DSDD DSHD $4.70 $8.95 $8.50 $16.95 II I ----------EPROIIS 2716 .... ..... .. .. $9.95 2732A .. .. .. .... . $7.50 27C32 .. ....... $11.50 2764 ............. $6.50 27C64 .......... . $7.00 27128 .... .. .. .. . $7.50 27C128 ......... $8.00 27256 ........... $8.50 27C256 .. .. ..... $9.00 27512 ......... $12.50 27C512 .... .. . $13.50 27C1001 ... .. $23.50 RAMS 6116 .... .. ....... $4.50 6264 ........ ..... $9.50 62256 .... .... . $17.50 628128 ...... . $60.00 SERIALPOFIT CHIPS 8250 .. .... ... ... . $7.50 82450 .. ....... $17.50 16C450 ....... $18.00 16C550 .. .. ... $29.50 *************** ~ ~ ~-~ - n r PRIMES~ S DYNAMIC RAMS 4164-10 ........... $3.25 41464-08 ... ... ... $2.75 41256-08 ......... $2. 75 414256-08 ....... $7.95 411000-08 ....... $7.95 256KSIM,SIP. $23.50 IM,SIM,SIP .... $79.00 4M SIM,SIP . $335.00 llfGUUTORI 7805T ... ........... $0.50 7812T ...... ........ $0.50 7815T .......... .... $0.50 7905T .............. $0.60 7912T ...... ........ $0.60 7915T .............. $0.60 317T ................ $1.50 337T ................ $2.10 723 .................. $0.80 DIDDEI IN4148 .......... .. $0.04 IN914 ......... ..... $0.05 IN4004 .......... .. $0.08 IN4007 ............ $0.10 IN5404 ............ $0.20 IN5408 ............ $0.25 TIIMIISTORS BC547/8/9 ........ BC557/8/9 ........ B01 39 .............. B0140 .............. TIP31C .... ......... TIP32C ............. MJ15003 ......... MJ15004 ......... MJ2955 ........... 2N3055 ............ $0.15 $0.15 $0.45 $0.45 $0.80 $0.80 $6.50 $6.50 $2.50 $1.50 LINEAR l SPECIAL FUNCTION 1488 ................ $0.50 1489 ................ $0.50 8250 ......... ....... $7.50 82C450 .......... $17.50 16C450 .......... $18.00 16C550 .......... $29.50 XR2206 ............ $8.50 ICL7106 ......... $14.00 324 .................. $0.75 339 .................. $0.50 358 .................. $0.90 555 .. ................ $0.45 741 .................. $0.55 IRIDOES W04 ........... ..... BR64 ...... ......... BR104 ............. BR254 ............. BR354 ............. LEDS 5mm RED ........ 5mm Green ..... 5mm Yellow .... $0.50 $1.50 $2.50 $3.50 $3.95 FREE PRICE LIST UPON REQUEST $0.15 $0.25 $0.25 ELECTRONICS & COMPUTER SUPPLIERS 289 LATROBE ST MELBOURNE, VICTORIA 3000 PHONE: (03) 602 3499 FAX: (03) 670 6006 MAIL ORDER HOTLINE: (008) 33 5901 ALL MAJOR CREDIT CARDS WELCOME POSTAGE RATES $1.00-$9.99 ......... $3.00 $10.00-$24.99 ..... $3.50 $25.00-$49.99 ..... $4.50 $50.00-$99.99 .... $5.50 $100.00-$199.00 $6.00 $200.00+ ............. FREE M AY1992 61 CORD GRW GROMMET PHONE 1 PHONE 2 REAR PANEL ACTIVE (BROWN) NEUTRAL (BLUE) • • • 240VAC T1 • • • 01000uF • • • T2 • ,. G• 7812 e+46V O• • • FRONT PANEL Fig.3: this diagram shows how the parts are installed on the PC boards. Note that the two 1.2kQ 1W resistors on the logic board are soldered to PC stakes (see text). The two boards are connected together using 4-way telephone cable. with the audio signal coupled by the 600:600 ohm transformer (T3). When one party subsequently replaces the handset, pin 3 of IC3d will go high and attempt to ring the idle phone. Ringing will not proceed, however, because the flipflop is set (Q-bar low), thus depriving IC2b of the required logic high. The flipflop remains set until both handsets are replaced and IC2a resets the logic to its standby state, ready for another call attempt. Ring sequence The ring cadence can be easily customised to suit your applicmtion. Some constructors may choose to build the 62 SILICON Cf:IIP unit as close to the Australian standard as possible, whereas others may opt for an" American-sounding" ring, or some other sequence. The standard ring cycle that we are familiar with has the following pattern: 400ms on, zooms off, 400ms on, 2s off, and so on. To generate this sequence, we would normally require a zooms clock period and a counter with 15 outputs (ie, we would have to use two counter !Cs in cascade). Another way is to use a single standard decade counter, the 4017, and addJogic to make it suit the application. In this circuit, the 4017 (IC4) is fed from a 2.5Hz clock (IClf) which pro- vides a period of 400ms per step. However, as the output corresponding to the zooms "off" period goes high (output "2", pin 4), the clock is doubled in speed to give the required zooms period. This is easily accomplished using PNP transistor Q4 and the lOµF capacitor wired between its emitter and collector. In operation, Q4 is normally conducting and the lOµF capacitor across it is short circuited. However, when output "2" (pin 4) of IC4 goes high, it turns off Q4 and this switches the lOµF capacitor in series with an existing lOµF capacitor in the clock's timing circuit . . Because the two capacitors are in series and of the same value, the total capacitance seen by IClf is now halved. The clock therefore doubles its frequency, giving one zooms burst to step the counter past output "2". When output "3" goes high, Q4 turns back on again and the clock reverts to its 400ms period. Diode DB resets the counter when output "9" (pin 11) goes high to limit the off period to 2s following the second 400ms ring. The ring sequence is then repeated. Although Fig.2 shows the circuit arrangement for the Australian ring standard, you can easily customise the ring to suit your own requirements. For example, the clock frequency can be adjusted over a wide The two PC boards are housed in a · metal case & secured on 5mm spacers using machine screws & nuts. The screw terminals on the rear panel provide the connections for the lines to each telephone. range using VR1, or the ringing sequence can be changed by using different counter outputs. If you don't require the standard "ring-ring" cadence, omit Q4 and replace the lOµF capacitor between its emitter and collector with a wire link. check the circuit boards for undrilled holes and damaged tracks. In particular, check the logic board around ICZ & IC3, since the tracks here are very fine. Check also that the mounting holes and the holes for the transformers, filter capacitor, relays, PC stakes and trimpot are large enough. Fig.3 shows the wiring details. Begin by installing PC stakes at all exter- Construction Construction is straightforward, with most of the parts accommodated on two PC boards. One board (code SC12105921) carries all the logic circuitry, while the second board (code SC12105922) carries the power supply components. Before mounting any of the parts, TABLE 1: RESISTOR COLOUR CODES 0 0 0 0 0 0 0 0 No. 3 2 6 2 2 3 2 Value 4-Band Code (1%) 5-Band Code (1%) 100kQ 47kQ 10kQ 1.2kQ 680Q 2200 150Q brown black yellow brown yellow violet orange brown brown black orange brown brown red red brown blue grey brown brown red red brown brown brown green brown brown brown black black orange brown yellow violet black red brown brown black black red brown brown red black brown brown blue grey black black brown red red black black brown green black black brown MAY 1992 63 0 - ( \J (]\ -- If) C) ( \J u (I) 0 0 0 0 0 (\J (\J (J\ If) 0 -( \J u (I) 0 0 Fig.4: here are the full-size patterns for the two PC boards. 64 SILICON CHIP nal wiring points on the power supply board, then fit the 7812 voltage regulator, capacitors and transformers. Take care with the orientation of the voltage regulator - see Fig.2 for the pin connection details. Moving now to the logic board, install the five wire links before mounting any of the other parts (one link runs underneath two ICs). Once these are in, fit PC stakes to the external wiring points and install the remaining parts as shown, leaving the relays and transformer until last. Note that you should also fit PG stakes at the mounting points for the two 1.2kQ current limiting resistors (in series with ZD1 & ZD2), since these values may have to be adjusted when the circuit is operational. The prototype was housed in a metal case measuring 256 x 76 x 155mm and fitted with an adhesive aluminium label. After attaching the label, drill mounting holes in the front panel for the two LEDs, then drill the rear panel to accept the mains cordgrip grommet, an earth lug mounting screw and the screw terminals for the telephone lines. The two PC boards can be used as templates to mark out their mounting holes on the bottom of the case. Once the holes have been drilled, secure the mains cord to the case using the cordgrip grommet and solder the Active (brown) and Neutral (blue) leads to the power supply board. The Earth lead (green/yellow) is connected to the earth lug on the rear panel. This lead should be made longer than the Active and Neutral leads, so that it will be the last to break if the cordgrip grommet comes adrift. Once the mains wiring has been completed, mount the two boards in the case on 5mm standoffs and secure them using screws, nuts and star washers. The remainder of the wiring can now be completed as shown in Fig.3. This includes a 4-wire connection between the two boards, plus wiring from the logic board to the front and rear panels. Testing Before applying power, go over the project carefully and check for wiring errors. In particular, check that all parts are correctly oriented and that the mains cord is securely held by the cordgrip grommet. When you are satisfied that everything is correct, switch on and check the supply voltages. The output of the 7812 regulator should be at +12V, as should pin 14 ofIC1, IC2 and IC3, and pin 16 of IC4. The positive terminal of the 3300µF filter capacitor should be at about +46V. Exercise caution when making these measurements, as mains voltages are present tended life for carbon granule type transmitters. The level of sidetone (ie, the level at which you hear your own voice) is also be reduced. Of the phones tested, many gave reliable communication with as little as lOmA of loop current, although one Siemens model would not send DTMF tones from its keypad until it . had about 25mA flowing. Fault finding The two 1.2kQ lW loop current limiting resistors may have to be reduced in value for telephone lines of considerable length. Generally, you should aim for loop currents of 10-25mA. You can check this current by connecting your multimeter across each telephone while it is on-hook. on the underside of the power supply board. Assuming that the supply voitages check out, short pins 4 and 5 of one of the optoisolators (IC5 or IC6). One of ring relays should now begin operating, according to the programmed ring sequence. Trimpot VR1 can now be adjusted to give the correct clock period. If you want to simulate the Australian ring standard, just adjust VRl so that each complete ring cycle lasts three seconds (ie, 400ms on, zooms off, 400ms on, Zs off). Alternatively, you can connect the two telephones to the circuit, take one of them off-hook, and adjust Fig.5 (below): this full-size artwork can be used as a drilling template for the front panel. VR1 until you get the correct "sound". Installation The values of the current limiting resistors in series with ZD1 and ZDZ may have to be adjusted according to the lengths of the individual lines. Generally, a loop current of 30mA should be considered the maximum. For most in-house or house-togarage use, 1.ZkQ 1W resistors (as shown on Fig.2) will do the job. However, lines of considerable length require lower value resistors because the resistance of the cable itself provides a certain amount of current limiting. If built solely for use as an intercom, the loop current can possibly be reduced to as low as 10mA. The benefits of lower loop current include longer operating distances and ex- If you strike problems, first check that all ICs have+ 12V on their supply pins. You should also check the boards for missed solder joints and for solder shorts between adjacent IC pins (make sure that the power is off). Next, trace through the gates with a logic probe or a digital voltmeter to check that the input logic is operating correctly. Check that pin 12 of IClb, pin 10 of ICld and pin 4 of ICZ are all high when both phones are on-hook. Pin 4 ofICZa should switch low when one phone is taken off-hook. If you don't get the correct readings here, check the optoisolators and the input buffering circuitry (IC1a-IC1d). Table 1 lists a number of possible symptoms and their likely causes. By following this table carefully, you should have little difficulty in tracking down any likely faults. References (1). Telephony, Volumes 1-5. Postmaster-General's Department, Australia. (2). Telephony and Telegraphy. Sydney F. Smith. Oxford University Press. Caution This intercom must not be connected to Telecom lines. It is intended only for use on lines completely separate from Telecom installations. TELEPHONE INTERCOM 0 0 POWER CALLING MAY 1992 65 ROLEC OFFICIAL DISTRIBUTORS FOR: RD AUSTRALIA DISTRIBUTORS ROLEC DISTRIBUTORS AUSTRALIA PTY LTD 20-22 Hilly Street Mortlake 2137 NSW Australia Ph: 61-2-7 43 3808 Fax: 61-2-736 3732 Telex: AA 20186 ROLAUS NOl<IA CONSUMER ELECTRONICS 2M213 2M218H A670 1H 2M214 2M218J A670 03H NEW LOCATIONS OPENING SOON: MELBOURNE (5) • DARWIN • N.Z. • TASMANIA • PERTH (2) • BRISBANE Microwave Ovens These capacitors are used in vo ltag e doubler circuits in high vo ltage microwav e oven transformers. In these applications, the capac itor must be capab le of withstanding an AC voltage equal to twice the peak voltage of the transformer output voltage . Oolll••·•c ... • 170-HOOYAC N50H1770G N50H2170G N50H2 570G N50H 1775G N50H2175G N50H2575G NSOH I 780G NSOH21 BOG Ns0 H2s80G N50H1785G NSOH1785G N50H2585G N50H1790G NSOH2190G N50 H2590G N50H1795G NSOH2195G N50H259SG NSOH1710G NSOH1710G N!!iOH2 51 0 G NSOH17 10G NSOH 2 110G NSOH1711G NSO H2111G N!!iOH1712G NSOH2112G 0 .70 0 .70 0 .70 0 .75 1700 2 100 2 500 1700 0 .75 0 .80 0 .80 2500 1700 2 100 2500 1700 2100 2500 1700 2100 2500 1700 2 100 2S00 1700 2100 2500 1700 2 100 1700 21 00 1700 2100 o.eo 0 .85 0.85 0.85 0 .90 0 .90 0 .90 0 .95 0 .95 0.95 1.00 1.00 1.00 I.OS 1.05 1.1 0 1. 10 1 .20 1.20 A A A A .A A A A A A A A A 1.25 1.25 1.25 1.25 1.25 1 25 1 25 1.25 1.25 1 2s 1.25 1.25 1 25 1.25 1.~5 1.25 1.25 1.25 1.25 1.25 1 .25 1 .21!1 1.21!1 1.25 1 .25 1.25 1 .2 5 2.so 3.31 3 .75 2 .50 4. 25 2.50 3.31 4.25 3 .oo 3.31 4 .25 3 .00 3 .31 4.75 3.00 3 .31 4 . 75 3.00 3.31 4 .75 3.00 4 .00 3 .00 4 .00 3.13 4.00 e 3 .5 84 .0 95 .3 63. 5 84.0 108.0 63.5 84 .0 108 .0 1e .2 84 .0 108.0 7 6 .2 84 .0 120. 7 76.2 84.0 120.7 7 6 .2 8 4.0 120.7 76.2 101 .6 76.2 10 1.8 79.S 101.6 Typlc•I 8 1lH for ou,1 C•p•cll,nc• A•Ung, N84H2295G 0 .67 + 0 .28 2200 1.75 2.56 0 .33 2200 1.75 2 .56 68 N64H2512G 0.90 + 0 .48 2500 1.75 4.06 102 N64H2210G 0 .70 + A ea A• DenotH • tock ltema Non-ll•t•d 1t111ma • Dellvary on appllcatlon DIODES D200 - D201 - D208 SHORT PROTECTOR D209 SHORT PROTECTOR & DIODE COMPLETE LAMPS CL815 15 WATT E17 240 VOLT CL816 25 WATT E17 240 VOLT Arco Australian AMP BKC International CKE Comspec Fox Electronics General Electric Harris Harwin lgnis Intel lntersil Johnson Components Kautt & Bux K G Kitagawa Ind. Kriesler Litton MA / COM Maida Marantz Motorola National Electronics NEC Panasonic Parker Magnetics Philips Pulse Engineering Pye Rank Arena RCA RCD Components Redpoint Samsung Semikron Semtech SFE Technologies SGS-Thomson Sharp Siemens Sony Star Printers UTC Transformers Vitelec Warth Whirlpool A full range of products available on request ADELAIDE ROLEC DISTRIBUTORS (S.A.) Pty. Ltd. 5-9 Rundloe Street, Kent Town SA 5067 Phone: (08) 366 0000 Faxstream: (08) 362 0000 ALCORA ELECTRONICS 94 Chandos Street, St. L.eonards NSW Phone: (02) 906 1253 Faxstream: (02) 906 1263 ROLEC DISTRIBUTORS NEWCASTLE 1 Vista Parade, Belmont NSW Phone: (049) 47 7701 Faxstream: (049) 4 7 7018 ROLEC DISTRIBUTORS AUSTRALIA PTY. LTD. 20 Hilly Street, Mortlake NSW Phone: (02) 743 3144 Faxstream: (02) 736 3732 Telex: AA20186 ROLEC DISTRIBUTORS HORNSBY Unit 2, 107 Hunter Street, Hornsby NSW Phone: (02) 482 1944 Faxstream: (02) 482 1309 VINTAGE RADIO By JOHN HILL Aligning vintage radio receivers, Pt.2 Last month's Vintage Radio column covered the various components involved in receiver alignment. We now move on to the equipment used for alignment and describe how it is used. It is both easier and quicker to align a superhet receiver if you have the right equipment. The right equipment in this case is a radio frequency (signal) generator and an output meter. However, as these instruments are not always available, we will also describe the alignment procedure without them. Signal generators A signal generator does exactly what its name implies - it generates RF signals which can be injected into a radio receiver at various points. It is usual to modulate the RF signal with an audible frequency of around 400- lO00Hz, so that the signal can be heard in the receiver's loudspeaker. Signal generators are tunable and any desired frequency can be obtained simply by selecting a frequency range and setting a calibrated dial. Modulating the RF signal with an audible tone is similar to what happens at a radio station's transmitter, where the radio frequency signal (carrier) is modulated by audio frequencies (speech, music, etc). A simple way oflooking at this is to think of the RF signal as the vehicle and the audio frequency signal as the passenger. The receiver is designed to receive, amplify and separate the two signals, for An RF (signal) generator and an output meter make the task of receiver alignment much easier. This photo shows a Heathkit RF signal generator and a standard multimeter. 68 S ILICON CHTP it is only the passenger that is of interest in the end. Likewise with the signal generator. It is of little use injecting a radio frequency signal into a receiver if we cannot monitor it. If we modulate the RF signal with an audio signal, we can both hear it and see its strength on an output meter. The main advantage of using a signal generator is that it supplies a constant and stable signal at any chosen frequency. Also, its amplitude can be varied as appropriate during the various alignment stages, thus making it more convenient to use than a distant radio station. Output meter An output meter is used to measure the output signal strength of the receiver being aligned. Its two leads are usually connected to the anode of the output valve and to the chassis. In some cases, it can be connected across the loudspeaker's voice coil but this method is not successful unless the meter is particularly sensitive. Some multimeters have a special output socket (to accept the lead connected to the output valve anode) but, unfortunately, many lack this refinement, which makes things a little more difficult. However, any multimeter with an AC volts range can be easily adapted for use as an output meter. To explain, not all voltages are pure AC or DC - some can be a mixture of both. In the case of an output valve, the AC audio signal which drives the loudspeaker is superimposed on a DC voltage of about 250V which is applied to the valve's anode. An output meter is designed to ignore this DC voltage and display the AC (audio) component only. This seemingly difficult task is easily accomplished by placing a high instantaneous level of the voice or music signal being received. On the other hand, if using a signal generator, the meter needle will remain steady because the audio signal is constant. Under these conditions, it is very easy to align a receiver for maximum needle deflection on an output meter. Alignment tools IF transformers are adjusted by one of two means - either by using trimmer capacitors, as shown at right, or by adjustable iron slugs (left). Some early transformers may only have one adjustment instead of the usual two. voltage capacitor (of about .047µF, or larger) in series with one of the meter leads. This capacitor blocks the DC voltage but allows the AC voltage to register on the meter. Therefore, any multimeter with AC ranges can be used as an output meter by making up a special lead with a suitable capacitor in series with it. Such a lead requires a small insulated alligator clip at one end and a banana plug or whatever to suit the meter socket at the other end. The capacitor connections must be well insulated. If you have a multimeter with an output socket, the blocking capacitor is already built into the meter. However, it is advisable to check this capacitor. Either check the circuit for specification or open the back of the multimeter and have a look. The capacitor must have at least a 400V rating and should ideally be a modern plastic type if it is to be used on valve receivers. I speak from experience. The only meter I have with an output socket has already blown its original 400V capacitor and now has a 630V replacement. Perhaps the capacitor was faulty but it sure did burn out. Correction: it blew out - paw! If you don't have a signal generator, then there is little point in using an output meter in the manner described above. When using radio stations as a signal source, an output meter will flicker up and down according to the This multimeter has an output socket with a high-voltage capacitor in series with the meter circuit to block any DC components. It can thus be used to monitor the output signal level by connecting it directly to the anode of the output valve. Not all multimeters have this function. The tools used for alignment adjustments are confined (in most instances) to insulated screwdriver blades. However, the everyday screwdriver is not the best tool to use. Simply touching a metallic screwdriver blade onto some alignment components will change the alignment. And in some cases, it can cause -:1 high tension short circuit or give Lie operator an electric shock. The recommended tool in the old days was a non-metallic screwdriver fashioned from a toothbrush handle or similar insulating material. Such a tool is quite satisfactory provided it will turn the adjustment screw. Unfortunately, plastic screwdriver blades are a bit gutless when it comes to torsional strength. If the adjustment screw shows any degree of resistance, then the blade simply snaps off. In addition, many modern insulated alignment tools are moulded from a flexible plastic material which is often inadequate for valve radio applications. I recently made a couple of alignment tools from 6mm-diameter acrylic rod. Into the ends of these rods are cemented very short metal screwdriver blades which have been spe- An AC voltmeter can be used as an output meter simply by fitting a .047µF 400V capacitor in series with one of its test leads. The capacitor blocks the DC voltage on the anode of the output valve but allows AC signal voltages to register on the meter. MAY 1992 69 TABLE 1 Variations in intermediate frequencies as taken from the 1938 Australian Radio Service Manual kHz kHz kHz 175 392 180 450 452.5 455 456 457.5 458 468 462.5 465 470 472 182 250 252 252.5 455kHz is by far the most common IF for valve radios. However, many early superhets had odd frequencies, with 175kHz being quite common in the 1930s. When aligning the IF transformers on a superhet, the generator signal is jnjected into the circuit via the grid of the frequency converter valve. If the valve does not have a top cap, a connection on the appropriate fixed plates of the tuning gang will do the job just as well (see text). cially made in various sizes from high carbon steel. These alignment tools give the best of both worlds in that they are reasonably strong and the small metal tip has little or no affect on the alignment setting. In some cases, however, the alignment components are so stiff that they can only be turned with a standard screwdriver. This is of no great concern provided the tool is used properly. First, the blade needs to be fully insulated to within one millimetre of the tip, to prevent short circuits and possible electric shock. This can be 70 SILICON CHIP done using insulation tape or a piece of heatshrink tubing of appropriate size and length. Second, after each adjustment, the metal screwdriver must be removed from the screw slot so that the output meter can display the true reading. Alignment may be a bit slow and tedious by this method but sometimes there is no alternative. If the adjustment ~crews are tight, then a metal blade is the only way to move them. Alignment procedure The correct starting point for superhet alignment is at the interme- diate frequency (IF) transformers. The first step is to connect the RF generator leads to the grid of the frequency converter valve and to chassis. If you have trouble working out where the grid is on the converter valve, it is usually the top cap that connects to one of the tuning capacitor gangs. If the valve has no top cap grid connection, trace the wiring to determine which tuning gang section connects directly to the converter valve and connect the generator lead to the fixed plates of that particular section (or to the corresponding valve socket connection). It is important to inject the correct frequency into the receiver in order to tweak up the IF transformers. Today, the industry standard IF is 455kHz and this frequency has been established long enough for it to apply to many valve receivers as well. However, some early superhets had quite weird IFs, as a quick look at Table 1 will show. The set's IF transformers should be tuned to the frequency that they were supposed to operate on but this frequency is not always known. Now if a receiver with a 460kHz IF is aligned to 455kHz, it will not prevent the receiver from working - although it will work better when aligned to the correct frequency. In particular, it may upset the dial calibrations slightly and/or the front-end tracking. More on this later. One way to ascertain an unknown IF is to connect the signal generator to the receiver and adjust the generator dial until maximum signal is heard in the loudspeaker. Provided that the IF transformers have not been previously tampered with, the generator dial should indicate the receiver's IF. Once the IF has been established, the IF transformers can be adjusted RESURRECTION RADIO Vintage Wireless Specialists A metal-bladed screwdriver can be used as an alignment tool when the adjustment screws are tight. This particular tool has an insulated blade with only the tip exposed. Such a precaution is necessary when adjusting early IF transformers to prevent short circuits and possible electric shocks. for maximum output. This should be done with the tuner plates completely out of mesh, the volume control at maximum and the signal generator adjusted to feed in just enough signal to activate the output meter. AVC action There is a very good reason for these level settings and that is to effectively disable the AVC (automatic volume control) system. If the AVC is operating, it will try to counteract any increase in output signal due to improved alignment, thereby making the improvement less obvious. Since most AVC systems are (level) delayed, keeping the input level down renders them inoperative. As sensitivity increases with alignment, the input level from the generator should be progressively These two special alignment tools were made using acrylic rod and metal screwdriver tips. The small steel tips were cemented into the ends of the rods. decreased, to keep the output approxi mately constant. If an off-air signal must be used, there is another way to set up an output meter, this time so that it monitors the AVC system. By using a stronger (off-air) signal, the AVC system will be activated and, by monitoring this , we can measure the effect of adjustments. The AVC action can be monitored by measuring the voltage developed across the cathode bias resistor of the IF amplifier (typically 3V). As alignment progresses, more AVCvoltage is applied to the valve grid, less current is drawn, and less cathode bias is generated. So you simply adjust the IF transformers for a dip in the meter reading, rather than a peak. Note, however, that the meter may not respond to adjustments to the IF secondary winding. The AVC voltage is normally taken from the primary of this transformer. But all earlier stages (aerial, RF, oscillator and IF primary) can be monitored. When making these adjustments, it matters little in what order they are done provided that the trimmers or cores are peaked a number of times. Some adjustments will be sharper than others. At this stage the IF transformers are aligned. The next step is to align the aerial and oscillator circuits. This will be covered in next month's Vintage Radio. SC Repairs - Restoration - Sales Our skilled technicians offer QUALITY repairs and restoration. We also have a large stock of bakelite and timber radios fully restored and for SALE. Parts are available for the enthusiast, including over 900 valve types, high voltage capacitors, transformers, dial glasses, knobs, grille cloth etc. Circuit diagrams for most Australian makes and models. Send SAE for our catalog. WANTED: Valves, Radios, etc. Purchased for CASH Call in to our showroom at: 51 Chapel Street (PO Box 1116), Windsor, Vic 3181. Telephone: (03) 529 5639 Our first full catalogue of our huge range of electronic components and kitsets is nearing completion and will soon be del_ivered to those requesting a copy - FREE! To secure your copy, please fill in the coupon (or copy details), send together with 3 x 45(1: stamps for postage and we'll send a catalogue, hot off the press! You'll also receive updates, bonus offers, specials, etc. during the year AND each month until June you will be in the draw for a free SCOPE PH20 soldering ironl Q 'e,o/ Please send me a FREE catalogue ~t I have enclosed stamps for postage Name:. Address . . Postcode. 'it\ ALL ELECTRONIC COMPONENTS 118-122 Lonsdale Street. Melbourne. v,c. 3000 Telephone (03)6623506 Fax . (03)6633822 MAY 1992 71 AL TRON/CS - SETTING NEW STANDARDS Altronics is proud to announce a new standard in Warranty. Because we stand behind our range of qµality products we have extended the guarantee period to 6 months - Double that of our competitors! ' May will prove to be an exciting month with arrivals of many new kits and products, an excellent time to try our famous 24 Hour express delivery Australia wide to all capital cities and suburbs. Get 240V AC from 12V DC! Great for camping, on the farm, boats etc. The All New Powerhouse 1200W Inverter (EA Feb '92) This new design of Power Inverter wlll provide 1200 Watts of power from a heavy duty 12 o, 24V battery. Using the latest Mosfet output stage and toroidal transformer this inverter is efficient and will deliver high surge currents. The Powerhouse has been designed not only for rugged bullet proof operation but for ease of construction, two PCB's hold all circuitry with one inter-connecting cable. (7 wires). Thi• kit comH to you In I fully drllled, pre punched ch111l1 complete with 1llk ■crHned front panel. Auembly of the kit 11 1lmpllfled H the maJortty of component, mount on • llngle PCB. Thul vlrtu■ lly ellmlnatlng 111 external terminal,. Suitable for UHi In camping, boating, f11hlng, mining, remote Htllement1 etc. Feature■ :• Massive 1200W continuous 2400W surge will run almost anything• 12 or 24V operation selected via internal wiring • Low battery cut-out • Over temp cutout • ·:iircuit breaker for overload protection• Auto start circuitry for standby operation• Easy to construct Recharge Your Mobile Phone, or Run Your Electric Shaver from the Car Battery' This fantastic little unit is ideal for use with incandescent globes, (note this model inverter will not run fluorescent lighting) electric shavers, small radios and some plug pack operated devices, ie charging cordless drills and other rechargeatle battery appliances etc. Feelurea: • Operates off 12V DC • Battery connection leads provided • Light weight • Uses Mosfet devices • High efficiency • Low heat dissapation Baby Room Monitor (S.C. Jan '91) This TV transmitter enables you to transm it signals from the output of your VCR to a second TV set in the house without messy splitters . and cableis. Two versions available for videos with UHF or VHF outputs. NEW UHF Version FOR VHF Version '92 K K5860 5885 $74 .95 Digital Altimeter for Gliders and Ultralights (SC Sep/Oct '91) K 1180 $24.95 This Baby Room Monitor allows you to listen to your baby from a remote location using a conventional FM receiver. It runs from a single 1.5V AA battery and includes a muting facility so that it only transmits sounds above a certain level. 8 Using state of the art circuitry this supply will be a great asset to the enthusiast and professional alike. It uses switch mode principles which allows for smaller transformers, and heatsinking which means greater efficiency, less heat and lighter weight. Feature•: • Variable output • Variable current limit • Separate Earth Terminal • Individual Volt and Amp Meters • Constant 13.BV setting • Short circuit proof Sp ecifica tion ■: • Output voltage 0-45V • Output current BA <at> 35V, 6A <at> 40V • Load regulation 1% • Ripple and Noise 40mVp-p at BA 35V • Current limit 800mAB.6A • Over current limit 9A • Foldback current less than 2A (SC Jan '92) NEW FOR '92 Build this simple little device, and avoid getting caught out with a flat battery during your holidays. It simply connects into a 12V accessories power line, and shuts off the flow if the battery voltage drops to a dangerously low level. Ideal for battery powered camping fridges etc. Adjustable Cutout Variable from 10.9V to 11.9V. Includes Automatic or Manual Voltage Reset Function. If::;_;. LOW VOCTAGE CUT-OUT . __,,,,. __] ;----·~-::-~1 1-.~ ( ,,,-, 01.,~' J-!i :__ _:_j K4328 $24.95 Infra-Red Light Beam Relay ~~'"""~ ---. . _,~~ .. * is compact digital altimeter · n display altitude up to 19,990 feet with 10 feet solution. Accurate to better than 3.5 percent. A must for '.:hts etc. Op:;:sF;R9~;-itery Here's a simple project that monitors the power drawn from a 'master' socket and automatically switches on a 'slave' socket. It is Activate all Your Hi-Fi versatile, because it by Turning on just the can monitor one or Amplifier! several appliances plugged into the 'master' and switch on one or several devices plugged into the 'slave'. Ideal for Hi-Fi's or computers with peripheral hardware. K6070 $59. 95 Adjustable 0-45V, 8 Amp Bench Power Supply (SC Jan/Feb '92) K3360 $375 .00 Massive Powe, C Pab1/ity,1 Low Voltage Cut-Out for Cars and Boats NEW FOR '92 ,·- ·""'~ -·: · :::1$2.99 K6790 Kit Version $799.oo K6792 Built & Tested 12V Input $999 K 6793 Fully Fully Built & Tested 24V Input .00 (SC Dec '91) This simple project allows you to monitor a doorway or a path using an infrared light beam. When someone walks through the beam, it triggers an alarm for a 1 second period. Ideal door monitor for shops or for security around home or office. Requires 12V DC plugback (M 9002). NEW K1920 $32.95 ~~2R J. ••• GJ - ' 4 Channel Guitar Mixer and NEW Preamp FOR K5535$49.95 (SC Jan 1992) '92 This unit features separate bass, midrange and tre~le controls, very low noise and distortion, separate input level controls plus an output level control. Ideal for use with most musical instruments from keyboards to guitars to tape decks. In fact, you can feed it with just about any audio signal - it's not just limited to guitar outputs. • Dl1tortlon: (at 1kHz and 1OOmV input) less than 0.0075% • Frequency ReaponH : 18Hz-35kHz (+/-3dB). The kit includes PC Board, potentiometres, input sockets and all specified components. The kit does not include the optional ground plane, nor the 15V power supply board. Low Cost 'Karaoke' Adaptor (EA Nov '91) It's time to bring out all those hidden vocal talents that you've always known were there. With this project you can remove the lead vocal from almost any recording, and replace it with your own via a standard microphone. It's a great way to liven up a party! Kmo $34.s5 (SC June/July '91) Make your 1tage production a proteNlonal lhow wtth 1h11 new Lighting Mixer. Ideal tor amateur theatre groupe band1 etc. his great new kit enables you to U!ltomize your sound system In ur car or at home. The circuit mply connects between the audi urce and the amplifiers. There re two outputs, one for bass nd another provides signal for th equency range (i.e. one for bass, one This 4-channel lighting desk is intended for theatre, disco and music group applications. It has heavy duty circuitry and is able to cope with spotlights rated up to 1000 watts or more. It has been designed and built for the rigours of commercial use . You can flash each channel up to any brightness as set by the 'Flash Master' fader. Similarly, the 'Channel Master' control fades all lights up or down, to or from their individual fade settings. Two chaser faders control the rate and lamp brilliance when the unit is operated in chaser mode. Th e lights can be flashed to full brilliance or to an intermediate setting as set by the 'Chaser Master' fader. K assive crossover is required in the speaker one pe n + and -15V rails. The resu lt is much better sound 5570 $19.95 Surround Sound Decoder K 5585 $3 5815 $329.oo (E.A. Jan '92) , - - - - - - t Build this new surround sound processor and . ,' envelope yourself with the stunning realism ·' and dramatic sound impact available from SOW Mosfet Module surround-encoded videos or TV 50 Watts RMS into 8 Ohms. This great module features moderate power output at low harmonic distortion. Simple to build and compact in size this unit makes a great replacement module for your old Hi-Fi or buy two and make your own stereo amplfier. K 5115 transmissions. It can also enhance conventional stereo, by providing a rear or 'ambiance' channel. 0-30V Power Supply $49.95 Hi Syste (SC May '8 Stereo 50 + 50 Watt Midi-Style Amplifier Replace That Old Beaten Up Amp! (SC Feb and March '92) -'IHI ,-,: ~1"ffl\ll,)~ ,,,.,,, 0 w~ .,.,; :""' ""': ~~ , .... ,;,;oo #<J _ . _;(a. ,.:: " '_, I,~ zA h ,,., Economy Alarm Panel For Home, and Small Commercial PremlaH This is a 3 zone alarm control panel designed for the protection of homes and small cg_mmercial premises. It employs the latest advanced electronic circuitry offering the highest degree of quality and reliability. It will accept either active or passive norma ll y open or normally closed sensors making it both a versatile and effective protection system . 12V battery charger inbuilt. See Altronics '92 catalogue for full details. s 5480 $139.oo Flush/ Surface Mount Alarm Panel This amazing new model features just about everything you could imagine! Multifunction keyring remote control wi ll arm and disarm alarm (and activate central locking if fitted), chirp the horn , turn on car headlights. panic and even open the boot (if actuator fitted). One remote can control two alarms. Other features include: Starter inhibit, valet mode, central locking interface, flashes car indicators when tripped, auto reset plus much more!, s 5230 t249.oo 5231 ;Teplacement Remote S Control $48.50 DIRECT IMPORT PRICE l With stylish compact good looks this alarm blends smoothly into any residential or office decor by either fl ush mounting into the wall, or surface mount. 3 sectors 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 protecting entries. simple 4 digit access code tor operation. See Altronics '92 catalogue for full details. s 5490 $119 .oo UHF Microprocessor Controlled Wireless Security System Apart from the flawless operation of the system one of the great features is its application with rented or leased premises - let's face it, money spent on installing a wired system in your home or office, factory, etc is irrevocably lost when you move on. With this system you simply take it with you. Ultra high-tech and push button operation makes this unit a breeze to install and operate. Features 6 sectors plus 2 x 24 hour fire and tamper circuits. The S 5240 system includes main controller, 1 Passive Infra Red Movement Detector, 1 window or door Reed switch, wired siren. power supply, back-up rechargeable battery. and a special personal remote. All sensors are radio transmitters which means no wiring is neccessary (except for the plug pack and siren). The wh ole system is coded so it can not be interfe,ed with and can be changed any time by the owner. Each individual sensor can be eas ily set to operate on any sector. The main controller utilizes latest EEPROM technology which means things like selecting user on/off codes, isolating sectors are a breeze. Includes a myriad of other amazing features, too many to mention . Wireless Remo.le Keypad Call AL TRONICS today for a frH colour brouchure. Complete 1yatem Includes: 1 : ~i;;r~ in~~i Red Detector/ Tran smitter 1 x Door/Window reed Switch/Transmitter 1 1 1 1 1 1 s External Siren · 2015 C $15.95 x x x x x Hand Held remote Control/Tran smitter Horn Speaker - 10 watt/wired 240V AC adaptor 1.2Ah Back-up Battery Set of batteries for all transmitters 5240 Complete System Door/ Window Only $679 .OO eed Switch & Transmitter S 5247 $72.95 s 5255 $135.oo Interlocking Part, Unique design allows units to be D rawer, · 'dove-tailed' together. Drawers _ _ _ _ will not stick or seize. Single or pouble drawers available. · H 0235 Single $4.95 ea T 1250 $ 4 5 .oo This lightwe ight de-soldering iron allows components to be quickly and cleanly removed with one hand. Naturally it's SEC approved and comes with a cleaning wand. Can be used as a soldering iron. 240VAC 30W. Earthed. Simple cleaning ,, action. H 0238 Double $5.so ea Box T 1255 Replacement 1.5mm Tip $4.95 J 1252 Replacement 1.2mm Tip $4.95 All New IRODA Gas Soldering Iron Temperature Adjustable Soldering Iron A/B Computer Switch ~ : ·:: ····•,•-:, ,·,:.- ..-:,_:_:,:,::.:,:::::·: "trodo: Winner of the Taiwan Good Deolgn Award Now you can solder anywhere with this new gas soldering iron. Screwdriver temperature adjustable between 2500C and 450°C enabling very delicate soldering on low settings with surprising heat energy reserve on maximum setting. Relative temperature is indicated by LED iamp brightness. Now Two way printer/peripheral computer switch with D25 sockets. Allows two printers to be run off one computer and individually selected or allows one printer to be run off two computers and individually selected. D 1570 Normally $;,8'95 Feature• • See through gas chamber (no more guessing how much gas is left!) • Built in ignition cap• Uses standard butane gas• Comes with safety bench stand • Supplied with 2mm soldering tip and blow torch tip • Adjustable temperature from 400°C to 12000C • Can be easily refilled with standard butane lighter gas • Replacement tips are less than half price of some other brands! REPLACEMENT TIPS - ALL $4.95 ea IT 2455 Replacement Exhaust Port T 2451 Replacement 1mm Conical Tip T 2456 Hot Knife Tip T 2452 Replacement 2mm Conical Tip T 2457 Hot Blower Tip T 2453 Replacement 3mm Conical Tip T 2458 Blow Torch Tip T 2454 Replacement 3mm Chisel Tip T 2448 Weller Butane Gas Refill $5.95 u1ea 1tate ot the art ceramic heating element. T 2448 Normally $ ~ 5 NEW FOR '92 This Month $ 3 9 .95 This Month $ 3 9 .95 Universal Remote Control 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 existing functional remote. I Electronic Temperature Controlled , Temperature Selectable, Soldering Station. The MICRON T 2440 solderin g station offers the ultimate in controlled temperature hand soldering. Featureo: • Variable Temperature Control • LED Temperature Readout • Zero Voltage Switching protects CMOS Devices • Grounded Tip • 48 Watt Element • Thermocouple lmbedded in Heating Element for Precise Temperature Control • 24V Low Voltage Element • Rubber Silicon Lead • Chrome Plated, Iron Clad Ultra Long Lile Tips • New Improved Ceramic Element $139 T 2440 Normally $ % 5 , This Month Onl y .95 With this simple device you can monitor any door in your house. This two piece alarm consists of control box and magnet. The magnet simply mounts onto · the door frame while the unit is mounted on the door so that when closed, the magnet and control box are opposite. Easy to use on/off switch. Built in beeping buzzer sounds when tripped. Requires 9V battery. S 5315 A 1000 $69.a5 Micron Mk II Soldering Station Scoop Purchase On Door Alarms $15 G pR1cEl p.l,,1Az1N n,1, la the 1992 model of our fantutlc ubt.ch Duel Tree• 20 Meg Scope, There are over 3000 now In ••rtlc• throughout Aullra//e - Our cu,tomer, Include Unlveraltte,, R••••rch Eatabllahment, and lndu■ try SENSATIONAL VALUE Famous Labtech 20MHz Dual Trace NORMALLY $699 Oscilloscope ·~~- THAT's $100 OFF/ The '92 model is a dual trace 20MHz oscilloscope using a high brightness CRT. The vertical amplifiers have high sensitivity of SmV/ div and 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. Highly recommended for Thl1 fantaotlc tuner 11 the Ideal add-on to any aound 1y1tem. Can be u,ed a, background mualc aource In reatauranta, ahop1 etc or any PA appllc~tlon. Al10 a great upgrade for the home HI-FI. Featureo: Q 0158 This Month Only $599.oo ~~'"-.-.------------------------------4 0 0175 $49.95 ea Illuminated SPST Rocker Switches Amazing value! 24.ov AC inbuilt neon glows red. Panel cutout 18.6 x 13mm. s 3218 $1 .50 ea, or 10up $1 Pocket Sized, Signal Generator 'B ;J , -, TURN 12V DC TO 240V AC. This fantastic inverter will power lights, TV's, tools, electric shavers and a whole host of other appliances. Great tor camping, out in the bush and any plac11 where 240V is not available. Fe ■ ture,: • Complete with over current circuit breaker• Fused 240V output• Built in . panel meter to monitor output voltage • Strong steel case and chassis. Replace that old Dial Tuner! 1.\:.1' Sarvlce Workbench, Deolgn Laboratory, Manufacturer,, Unlver1ltle1 and the dedicated enthullaotlc. Ideally suited to Q 0156 (2 required). Superb quality. DC to 80 MHz. Max 600 Volts DC. Lead length approx 1.Sm. AM/FM PLL Tuner This pocket sized oscillator has all the features of a large Ii ~~I bench oscillator. 46 preset { ,..'-"'' .1 switched frequencies ranged / 1 · ~.- - ...... •• • -- -- ~ ' from 20Hz to 150kHz, eg: a, .., 1kHz, 1.2kHz, 1.5kHz, • "'....-~)"{• ~ 1.8kHz, 2kHz etc. Smaller /,:"• 'I' '' ,•. than most multimeters, this I ;;· • ·,_. is ideal for technicians, ! ::; servicemen, students and \·· -...._ · ~ •.. hobbyists who require an acc~rate and reliable oscrllator ready to use ...~ :..;!"' r~ anywhere I M"'' I ;.: '":f",. ,.,·•2~ I -~~.~-l:'J-im:c'j J Q 1542 Normally ~ o · This Mdnth Only $ 8 0 ,oo G!!:~i!'..i:.::. ,x CS ea • Digital LED frequency readout display • FET FM front end for high image rejection • Phase-linear ceramic filters are incorporated in both AM and FM IF section • Phase-lock loop (PLL) IC for FM multiplex stage • Dimensions: (W x H x D) 435 x 60 x 232mm • Weight: 3kgs. A 2210 Normally ~ . 0 0 , This Month $199.oo Our Top Selling 17 Range Digital Multimeter for an Amazing $39.95 With quality and features you would expect only on expensive meters the Q 1056 represents excellent value for money. Specification,: DC Voltage: Ranges 2-2000V AC Voltage: Ranges 200V, 500V DC Current: Ranges 200mA, to 10A Reol1tance: 5 Ranges 200 Ohm , to 2M Ohm Diode Teot: Test Current 1.0mA Test Voltage 3.2V Max Battery Te,t: Ranges 1.5V, 9V Loaded Current: 1.SV 100mA, 9V 6mA Q 1056 Normally ~ 9 5 This Month $39.s5 Q 1057 Carry Case to Suit $1 2.50 Cleane • High performance noise attenuating WtlY Pav $tf° earphones • Noise cancelling or More· · , ~ microphone• Cushioned head pad • '-\' , Super sturdy • Great performance • ~ I Awarded the Good Product D esign A w ard for Superb, professipnal pilot's headset will - CETDC in 1987. last a lifetime with reasonable treatment T his fantast ic New model just arrived! 80 x 80 x 25mm. Ideal for amps, power supplies, computers and just about anything else that requires effective cooling. Exceptional value for money. F 1050 $17.so High Performance Crossovers ', Crossover Frequency: 3.5kHz dB/Octave: 6dB * c 4005 $11.95 2 Way, 150 Watts RMS Crossover Frequency: 3.5kHz dB/Octave: 12dB C 4007 $ 2 6 .95 3 Way, 80 Watts RMS Crossover Frequency: 600-800Hz/5kHz dB/ Octave: 6dB c 400& $20.e5 3 Way, 150 Watts RMS Crossover Frequency: 600-800Hz/5kHz dB/Octave: 12dB C 4008 $ 4 9 .95 ' I standard button mounting. r:di~ae~f~~i~i~~[s ~r~~· 0 ~~!~~u~ Car Voltag e Adaptor Stereo Headphones with Dynamic Mic Glasses, Watches wire connection. ', Fantastic new model includes , :t ·r.r improved microphone and shielded ', C $27. 0335 95 cable, allowing even better "' <o performance! Now better. value for ~-------------many than before. Over 2000 $189 already sold Australia wide. C 9070 . .00 . etc. 2 Way, 80 Watts RMS New stylist model, with simple one handed operation. Uses Complete with approx 1.5m • Includes standard aircraft jacks. Ultrasonic Cleaner can earn its cost a hundred times over in cleaning Computer Connectors, PCB's, Switches, Relays, Jewellery, These models consist of only high quality components. PCB mounted quick connectors for easy and reliable If, Noise Cancelling CB Type Mlc Simply brill iant Mylar stereo headsets and dynamic mic combination. Speaker Speclflcatlona: 20Hz20,000Hz, 32 Ohm , 3.5mm stereo jack , 6.35mm stereo jack adaptor. Microphone Spece: Dynamic type, 300 Ohm, 100 Hz15,000Hz -80db <at> 1 Khz, 3.5mm Mono Jack M 8150 $ 1 6 .e5 Portable PIR Alarm c 9055 Entertainers Cardioid Microphone * Professional Performance and Appearance. Balanced mic with unbalanced canon to 6.5mm lead . Includes vinyl carry case and mic holder. Polar pattern: Cardiod Impedance: 600 50-15,000Hz Ohm Freq. re1pon1e: Sen1ltlvlty: -75 +/ -3dB Diaphragm material: Polyester film This handy unit simply plugs into your e lighter socket and presto! Gives you switc~able 3, 4.5, 6, 7.5, 9 and 12V DC at up to 800mA. Includes a range of output plugs. Reversable polarity. Great for pocket TV's, radios, portable CDs etc. $44.s5 • • A ready to go system, no installation required • Fully automatic operation , very user friendly • Large coverage area • Portable or wall mounted • Long life 9V battery operation (battery not included) • Battery low warning • Lightweight, compact and attractive. _$,P8'. __.o_o._T_h_is_M_o_nt_h_$_4_9_ ._oo_ ..... s _53_0_5 Super Heavy Duty Tripod $129 A tlt1C,n1, r~ J~,.., ... ., , ~ -'J,,.., 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 STANDARD DELIVERY & PACKING CHARGE $5.50 to 1Kg, $8 1Kg-5Kg AUSTRALIA WIDE - We process your order the day received and despatch via. Australia Post. Allow approx 9 days from day you post order to when you receive goods. OVERNIGHT JETSERVICE Up to 3Kg is $10.00, 3Kg to 5Kg is $23.00 - We process your order the day received and despatch via. Overnight Jetaervfce Courier for delivery next day Country areas please allow additional 24-48 hours. ~ _,,,=;_ 'D' Series Connectors Wai : ~g~ 069 Male solder connector DB9 Female solder connector P3020 069 Male 90' PCB connector .,_c_o_3_15_ _ _._95_ _ _ _ _ _ _ _ _ _ _ _-t : 069 Female 90' PCB connector DB9 Male straight PCB connector p 3050 069 Female straight PCB connector P 3090 069 Backshell Cover sAVE ovER p 3100 0B15 Male solder connector COMPETITORS P 3110 DB15 Female solder connector 0615 Male 90° PCB connector PRICES! DB15 Female 90' PCB connector This great new model holds an amazing p 3140 0615 Male straight PCB connector range of equipment. With rubber feet for p 3150 0615 Female straight PCB connector sure and stable grip. Anti-sway bars on p 3190 DB 15 Backs hell Cover legs prevents wobbling. Adjustable p 3200 DB25 Male solder connector height from approx 1 to 2 metres. p 3210 0825 Female solder connector Lightweight aluminium construction and p 3220 DB25 Male 90' PCB connector collapsable for easy transportation. p 3230 DB25 Female 90' PCB connector Removeable mounting plate makes this p 3240 0B25 Male straight PCB connector tri-pod ideal for amplifiers, speakers, p 3250 0625 Female straight PCB connector lighting etc. p 3290 DB25 Backshell Cover P3310 Spacer Screws pk 1O C 0520 .95 P 3312 Spacer Screw pk 100 $79 (il ~g:g :mg .. .. 10 Up $1.35 $1.35 $2.00 $2.00 $1.75 $1.75 $1.75 $1.55 $1.55 $2.25 $2.25 $1.90 $1.90 $2.00 $1.75 $1.75 $2.85 $2.85 $2.25 $2.25 $2.25 $4.45 $35.95 $1.20 $1.20 $1.80 $1.80 $1.60 $1.80 $1.80 $1.40 $1.40 $2.00 $2.00 $1 .70 $1 .70 $1.80 $1.80 $1.60 $2.40 $2.40 $2.00 $2.00 $2.00 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 $1 ). When phone ordering please request " Insurance". TOLL FREE PHONE ORDER - Bankcard , Visa, Mastercard Holders can phone order toll free up to 6pm Eastern Standard Time. Remember with our Overnight Jetaervfce we deliver next day. AL TRON ICS RESELLERS Chances are there is an Altronic Reseller right near you - check this list or phone us tor details of the nearest dealer. Blue Ribbon Dealers are highliQhted with a ■ These dealers generally carry a comprehensive range of Altron,c products and kits or will order any required item tor you. WA. COUNTRY ALBANY BP Electronics ■ (098) 412681 Micro Electronics (098) 412077 BUN■URY Micro Electron let (097) 216222 UPIRANCE Eeperance Communlcatlona (090) 713344 KALGOORLIE Todays Electronics ■ (090) 215212 MANDURAH Lance Rock Retraviaion (09) 5351246 PORT HEDLAND Ivan Tomek Electronlc1 (091) 732_531 ROCKINGHAM TV Joe's (09) 5271806 NT ALICE SPRINGS Farmer Electronics (089) 522388 DARWIN Ventronict (089) 853 622 VIC All Electronic Components (03) 6623506 TECS ■ (03) 6706474 BORONIA Ray Cross Electronics ■ (03) 7622422 CHELTENHAM Talking Electronics (03) 5842386 CROYDON Truscott Electronics ■ (03) 7233860 HUNTINGDALE Stewart Electronic Components (03) 5433733 PRESTON Preston Electronics ■ (03) 4840191 COUNTRY BAIRNSDALE LH & LM Crawford (051) 525677 BALLA.RAT Ballarat Electronics (053) 311947 BENDIGO KC Johnson ■ (054) 411411 CRANBOURNE Mart's Electronics (059) 968 200 MILDURA McWilliam Electronics (050) 236410 QLD Delsound PL ■ (07) 8396155 WEST END B.A.S. Audiotronics (07) 8447566 WOODRIDGE David Hall Electronics ■ (07) 8082777 MAROOCHYDORE MALS Electronics ■ (074) 436119 MARY BOROUGH Keller Electronics (071) 214559 NAMBOUR Nambour Electronics (074) 411966 PIALBA Keller Electronics (071) 283749 ROCKHAMPTON Access Electronics (East St.) (079) 221058 TOOWOOMBA Hunts Electronics (076) 329677 TOWNSVfLLE Super Solex ■ (077) 724466 SA Force Electronics ■ (08) 2125505 BRIGHTON Force Electronics ■ (08) 3770512 CHRIST IE$ 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 NSW David Reid Electronics ■ (02) 2671385 SMITHFIELD Chantronics (02) 6097218 WOY WOY Alphatran Electronics (043) 434 919 COUNTRY COFFS HARBOUR Coifs Habour Electronics (066) 525684 NEWCASTLE Novocastrian Elect.Supplies (049) 621358 WARNER$ BAY Vilec Distributors (049) 489405 WINDSOR M & E Elect. and Communications (045) 775935 iO,.<ONGONG ••~• '"''""'~ • ,,.,, """'· ,O~om ,,.mrn,;o, (00) ,,.,oo. INFRARED REMOTE CONTROL FOR MODEL RAILROADS, PT.2 In this second article on our new remote control for model railroads, we present the circuitry for the remote control receiver. This mates up to the pulse power board described last month. It also providesJatched and momentary outputs which can be used to control signalling, points and lighting on a model railway layout. The receiver circuit comprises eight ICs plus quite a few transistors and diodes, as shown in Fig.7. IC5 and IC6 are . the infrared remote control devices, while IC7, IC8, IC9, IC10a and ICl la provide the control signals for the pulse power circuit. Finally, IC10b, ICllb and IC12 are used for the various latched outputs. IC5 , a Plessey SL486 infrared preamplifier IC, is specifically designed for processing infrared control signals. This device features a differential photodiode input to reduce noise pickup and an automatic gain control circuit for improved operation in noisy By LEO SIMPSON & JOHN CLARKE" 76 SILICON CHIP ·' environments. It also incorporates two gyrator circuits and these allow the device to receive signals in high ambient lighting conditions, such as from incandescent lamps. The incoming IR signals from the remote control transmitter are picked up by photodiode IRDl which is connected across the differential inputs of IC5. The received pulses are then amplified and filtered before they appear at pin 9. Capacitors connected to pins 2, 3, 5, 6 and 15 ofICl roll off the frequency response of the gyrator and gain stages below about 2kHz. This effectively filters out any 100Hz signals produced by mains-powered lamps. Automatic gain control is provided by an internal peak detector which measures the output signal appearing at pin 9. A O. lµF capacitor at pin 8 filters the output of the peak detector and the resulting signal is used to control the gain of the first three amplifier stages. Signal decoding The signal from pin 9 of IC5 is directly connected to pin 1 of IC6, the decoder IC. This provides five BCD (A, B, C, D & E) outputs which can be either momentary or latched, depending on whether pin 5 is high or low. We have selected momentary operation by tying pin 5 high. In addition to the five BCD outputs, IC6 provides a Data-bar signal which goes low whenever a valid code is present on the A, B, C, D & E outputs. This signal is used to drive the ACKnowledge LED (LED 6) via a 3300 resistor. This LED therefore indicates whenever the remote control circuitry is receiving a valid signal from the transmitter. Pins 3 and 4 are the A and B rate inputs and must be connected to match the transmitter rate input connections. When the links to these inputs are left open, internal resistors tie them high (ie, to +12V). Three of the BCD outputs from IC6 are connected to IC7, a 4051 3-8 decoder (also known as an analog multi- plexer). Depending on the BCD code presented to its inputs, IC7 pulls one of its eight outputs (pins 1, 2, 4, 5, 12, 13, 14 & 15) high. Actually, what really happens is that one of the eight pins is connected to the common pin (3) which is tied to +12V via a 2.ZkQ resistor. The A, B and C inputs of IC7 are only decoded when the INHibit input (pin 6) is low. This input is connected to the Data-bar output of IC5 via a lOkQ resistor so that decoding is done only when valid data (low output) is present on the A, B and C inputs. Note that pin 6 of IC7 is also controlled by the D and E outputs of ICZ via diodes D15 and D16. Thus, when either the D or E output goes high, it inhibits IC7 and prevents any of its outputs from going high. Logic level conversion IC5 and IC6 operate between the +12V and +7V supply rails, while IC7 operates from +12V, +7V and 0V. The reason for this messy arrangement is because IC6 requires a 5V supply while the rest of the circuit needs to be compatible with the pulse power PC board which operates at 12V. Thus, IC7 not only decodes the signals from IC6 but also provides logic level conversion so that its output signals swing between 0V and +12V. The +12V supply for the circuit is · obtained from the +12V regulator on the pulse power PC board, while the +7V supply is derived from a separate -5V 7905 2-terminal regulator. This may seem a little unusual but the 7905 effectively operates as a current sink and subtracts its 5V from the 12V rail to give the +7V rail. Auxiliary outputs The five auxiliary control outputs are derived from the "5", "6" and "7" outputs of IC7 and the D and E outputs of IC6. The "5", "6" and "7" outputs of IC7 connect to the clock inputs of D-flipflops IC12a, ICl0b & ICl lb respectively. These are each Shown below is the completed pulse pow.er board, together with the handheld controller that's used to test it. These two items are identical to the Railpower project published in the April 1988 issue of SILICON CHIP, which means that you can easily convert the original project to remote control. MAY1992 77 "O ~ C") % Q n (/) C:: ~ I . 0 ~ v 1 CASE - • l 8 .1. O· - 6 a, 16VW .01s _ 40f!Jw<~~ -,- "':r DISABLE LEVEL· VR310k ,ra 9 100pF '" . GNO · IN. l T l A .1. 10M¾ .,. ' MOM' TiJT=F- + METER SET VR!ii2.2k ~~ (L, 1~\ "" 8 " , 9 ·--, I - INFRAREO RECEIVER BOARD RAILPOWER · 11 .,. 16 -,f -i/:,17 -1il!i 1 L R Js I ~~ ~ I I c .l I I "' . 100k~ I • I :3: ~ I 0.1 I .,. . t • C·~'" .,. .,. • I " _.,, .... '· t IC10b - . - -r---..::~.,___:!;i~---100k . 11• t J L r-c:_.,_____ "i ,--·· -1 I 0.1 r--+-- 1 l - 4 7 6 n sl 5 +12V I ~ ::1w 3' e !:i 14 1s 12 013 a: 1a: 2.._ 30 4w 7 IC 4051 ' COM '" II I MOMENTARY t='.f-· 100k 0.1 1- ~ +12V· ·"' OH 1N4002 .,_""'°''Nr-....-OUTPUTl1 15 016 r--:r+H-4----_J E ,~..a...l....JD15 2x1N4148 16 .,.7 a '•• 11 A 10 B C,t1"'"3------~-Jc 8 12 A 11· DISCHARGE ECB """ ACKNOWLEOGE ,t-'----4--¥,~---.!J ' 1N4002 204 6.8V ""'~" 400mW PLASTIC SIDE·1 .,. CLR 2 0.11 IC6 MV601 ,__ _ _ ___!!!U .,. r------~--41--J +12V ' K~ BPW50 "" LK1 1 OPEN=1 CLOSED=O T 6.BV 400mW 00pF 1 l 22 -+ 16VWT +7V <at>~"'-"""-"""'"~'"--'"~' 8.2k OUT .. 00, . ••• I 7905 r,.;,..-_. _.,. ___J ~ ~ 5 I 4 = ml 16VW SL486 3 1· FORWARD/REVERSEh E C VIEWED FROM BELOW OV +12V + 1 8P104 J~ ·" 10; • 16Vwr· >. L ~ i. ~ • ..j. .,. ,.;;;, 'q LEDS , .. . '"' ' +12V !~k l1N4002 +12V ' 019 ,020 1N4002 rt· . rt; ,moo, 021 ·'" ◄ Fig. 7 (left): the receiver board decodes the signals from the infrared transmitter. IC5 (preamplifier) & IC6 (decoder) are the infrared remote control devices; while IC7, IC8, IC9, IC10a & IClla provide the control signals for the pulse power circuit. IC10b, ICllb & IC12 are used to provide latched outputs for signalling, points switching & lighting. OV +12V BUZZER + connected with the D input tied to the Q-bar output so that each time their clock input goes high, the Q output changes state, from a low to a high or from a high to a low. This provides the latched output facility so that the first press of a button on the transmitter latches the relevant output on and the next press latches it off. The Reset inputs of these flipflops are all tied to an RC netw ork consisting of a O. lµF capacitor and lOOkQ resistor. This provides a power-on reset facility. At power-on, the O. lµF capacitor is discharged and so the reset line is momentarily held high until the voltage drops to OV via the lOOkQ resistor. This resets each flipflop so that its Q output is low. The Q outputs of IC12a, IClOb and ICl 1b are connected to transistors Q13, Q12 and Q11 to provide the latched outputs. Alternatively, the flipflops can be bypassed, via a link option, for momentary operation. Each of the three transistors can drive a 12V relay, connected between the collector output and the+ 12V supply. Each transistor has an associated diode to provide protection against any spike voltages that may be generated when a relay is switched off. Also associated with each transistor is a LED (LEDs 5, 6 & 7) which is lit when the output is on. The D and E outputs of IC6 drive transistors QlO and Q9, each via a 6.8V zener diode (ZD5 and ZD4) and a 2.ZkQ resistor. These provide momentary outputs only and, as with the other three outputs, have LEDs (LED4 and LED3) to indicate when they are on. The 6.8V zener diodes are used because the D and E outputs ofIC6 are at +7V when off (low) or +12V when on (high). When the outputs are at +7V, the zener diodes prevent the transistors from turning on. Note that Q9 and QlO are high gain Darlington tran- LE02 vdf I Fig.8: this is the parts placement diagram for the pulse power PC board. Note that IC2 is oriented differently to the other !Cs & take care to ensure th~t the two heatsinks used for transistors Q1-Q4 do not touch each other. Tnmpots VRl & VR2 set the maximum and minimum track voltages & must be adjusted as described in the text. sistors which are needed due to the limited base drive available from the D and E outputs of IC6. Train control The remaining circuitry on the receiver board is used to provide the various throttle functions via the pulse power board. You will need to refer to the circuit diagram of the pulse power board published last month to be able to fully understand the circuit description to follow. There are six connections from the receiver board to the pulse power board. Terminals 1 and 2 provide connections for the minimum and maximum speed setting voltages (from VRl, VRZ , ICla & IClb on the pulse power board). Terminal 3 is the speed control voltage (fed to pin 3, IClc on the pulse power board), while terminals 4, 5 and 6 provide the OV connection and the forward/reverse control. Each of the terminal 1, 2 and 3 points on the receiver board feature input protection for the CMOS circuitry. This takes the form of a 12n series resistor and 12V zener diode to ground (OV). The "O" and "1" outputs of IC7 (pins 13 & 14) correspond to the "faster" and "slower" buttons on the remote control transmitter. They con- nect to the control inputs of CMOS analog switches IC8a and IC8b. When pin 13 ofIC7 goes high (corresponding to the "faster" button being pressed), switch IC8a closes and the 2.ZµF capacitor at pin 3 of IC9a is charged via a 1OMQ resistor connected to the +12V rail. When pin 14 of IC7 goes high (when the "slower" button is pressed), switch IC8b closes and discharges the 2.ZµF capacitor via the lOMQ resistor connected to OV. The 2.ZµF capacitor can charge no higher than the voltage at Terminal 2 and can discharge no lower than Terminal 1. This is achieved by clamping diodes DlO and Dll and the associated resistive voltage divider between Terminals 1 and 2. The reason for using this fairly complicated capacitor charging, discharging and clamping arrangement is to give more linear charging and discharging and thus a better throttle response from the transmitter buttons. Sample and hold The voltage across the 2.ZµF capacitor is buffered by FET-input op amp IC9a which acts as a sample and hold circuit. This is desirable because the capacitor voltage is the throttle setting; you don't want it changing after it has been set. Since the op amp MAY 1992 79 - ' J f vO • Ov o o o _, V · OO c, OOOo VR5 000 following 4 7µF capacitor on the pulse power board will take several minutes to charge to the throttle setting, thus simulating the inertia of a real train. Conversely, if VR4 is set for minimum resistance, there will no inertia, which might be desired for shunting manoeuvres. Braking Fig.9: this is the wiring diagram for the temporary handheld controller. The numbers on the leads correspond to the numbers on the terminal block at the top of Fig.8. VR4 and VR5 set the running & braking inertia. FROM MAIN BOARD IC10a, IC8d and VR5 control the braking. IC10a is a D-flipflop which is normally set with its Q output (pin 1) low and its Q-bar output (pin 2) high. The high on pin 2 closes switch IC8c for the normal run mode (ie, normal running, brake not applied). When the stop output (pin 15) of IC7 goes high, flipflop IC10a changes state. Thus, pin 2 of IC10a goes low, causing analog switch IC8d to open. , At the same time, pin 1 of IC10a goes high and closes analog switch IC8d to discharge the 47µF capacitor connected to Terminal 3 of the pulse power board via trimpot VR5. This is the braking mode. The degree of braking is set by adjusting VR5. Hence, pushing the Stop button on the transmitter will cause the braking circuit to activate and it then stays that way until the Faster button is depressed (a momentary press is all that is required). When this happens, the "Faster" output of IC7, pin 13, goes high and pulls reset pin 4 of IC10a high via diode Dl4. This resets IC10a's Q output to low and the Q-bar output high. Switch IC8d now opens and switch IC8c closes to revert to normal running. Forward/Reverse This view shows how everything fits together inside the hand-held control unit that's used to test the pulse power board. A 6-way telephone cable makes a handy connecting lead. dr'aws an extremely low current (typically 50 picoamps), the rate at which the capacitor discharges will be almost solely due to its own leakage current. In practice, a typical 2.2µF tantalum capacitor should hold a voltage across it for five minutes or more before any noticeable reduction occurs. The output of op amp IC9a is at the 80 SILICON CHIP same voltage as the capacitor and is used to drive the speed setting meter via trimpot VR6. IC9a also drives inertia pot VR4. Normally, the following analog switch, IC8c, is closed and the run inertia pot connects to Terminal 3 of the pulse power board. This input has a 47µF capacitor which is charged via VR4 to set the train speed. If VR4 is set for high resistance, the Forward/reverse control is provided with flipflop ICl la. This is initially set at power-on with its Q output (pin 1) high and th~ Q-bar output (pin 2) low. These outputs are connected to Terminals 5 and 6 and thence to the pulse power board. Thus, when power is first applied, the circuit is set in the forward mode. When the Reverse output - pin 1 of IC7 - goes high, it pulls pin 4 of ICl la high to reset it. This causes the Q output to go low and the Q-bar output to go high. This is the reverse mode. Forward/reverse lockout However, there is more to the forward/reverse control than this. IC9b is an op amp connected as a comparator. It compares the voltage at Termi- nal 3 with the voltage set by VR3. In practice, VR3 is adjusted so that the output ofIC9b goes low only when the voltage at Terminal 3 is so low that the train is either running very slowly or has completely stopped. If the voltage at Terminal 3 is higher than the setting ofVR3, IC9b's output will be high; this is the normal condition while the train is running. The high output from IC9b turns on transistor Q14 and thereby pulls both the set and reset of IC11a low via diodes D12 and D13. This prevents ICl la from changing state and so prevents a change in direction; ie, gives forward/reverse lockout unless the loco speed is zero or very low. This condition causes the For/Rev Off indicator, LED 9, to light. If the For/Rev Off indicator is alight, you cannot change the direction of the loco. Construction We now come to the construction procedure for the pulse power controller. It is housed in a standard plastic instrument case and has two PC boards, as already mentioned. The power transformer and the receiver board are mounted on the base of the case, while the pulse power board is mounted on the lid. We will first describe the assembly of the pulse power board and show you how to get it going as a selfcontained train controller. After that, we will tackle the construction of the transmitter and receiver and marry them to the pulse power board. Fig.8 shows how the parts are mounted on the pulse power board. The 6-way connector is for the connections to the receiver board (Terminals 1-6), while the 16-way connector (actually two 8-way units) is for the rest of the connections. Assembly of the board can start with the wire links, small diodes and the resistors. When these have been installed, you can concentrate on mounting the four output transistors, the 3terminal regulator and their associated h eatsinks. Three heatsinks are required. Ql and Q3 are mounted on one heatsink while Q2 and Q4 are mounted on another. We made ours from 0.8mm aluminium (equivalent to 22 gauge), although the thickness is not important. For each two-transistor heatsink, we RESISTOR COLOUR CODES Value 4-Band Code (1%) 5-Band Code (1%) 10MQ brown black blue brown green blue yellow brown red red yellow brown brown red yellow brown brown black black green brown green blue black orange brown red red black orange brown 560kn 220kQ 120kQ 100kQ 47kQ 27kQ 22kn 15kQ 10kQ 8.2kQ 5.6kQ 4.7kQ 2.2kQ 1kO 8200 3300 1000 47Q brown black yellow brown yellow violet orange brown brown red black orange brown brown black black orange brown yellow violet black red brown red violet orange brown red red orange brown brown green orange brown brown black orange brown grey red red brown red violet black red brown red red black red brown brown green black red brown brown black black red gold grey red black brown brown green blue red brown yellow violet red brown red red red brown brown black red brown grey red brown brown orange orange brown brown green blue black brown brown yellow violet black brown brown brown black brown brown yellow violet black brown 120 2.20 brown red black brown red red gold brown used a piece of aluminium 30mm wide and 55mm long, with a rightangle bend 9mm from one end, which becomes the foot. Four 3mm holes need to be drilled in each heatsink, to take the two mounting screws for the foot and the mounting screw for each transistor. For the 3-terminal regulator heatsink, we used a piece of aluminium CAPACITOR CODES Value IEC Code EIA Code 0.1µF 100n 104 0.022µF 0.015µF 0.01µF 0.0047µF 22n 15n 10n 223 153 103 4n7 n10 472 101 100pF TRIMPOT CODES Value 220kO 100kQ 10kO 2.2kQ EIACode 224 . 104 103 222 red red black brown brown brown black black brown brown grey red black black brown orange orange black black brown brown black black black brown yellow violet black gol~ brown brown red black gold brown red red black silver brown 20mm wide by 45mm long, with a rightangle bend 9mm from one end. Three 3mm holes need to be drilled in it, two for mounting screws and one to secure the regulator. The three heatsinks should be secured to the PC board before the transistors and regulators are soldered into place. Note that the two transistor heatsinks must not touch each other otherwise they will short out the DC supply. Attach the regulator and the power transistors to their respective h eatsinks and then you can solder their leads to the board. Note that mica washers are not necessary for the transistors or for the regulator. Once the transistors and regulator are in place, the rest of the components can be mounted on the PC board. We suggesrthat you solder in the small transistors first , then the two trimpots, the 5W wirewound resistor, the four ICs, the four rectifier diodes and the capacitors. Leave the connector strips till last, otherwise they tend to get in the way when you are soldering other components. Note that ICl and ICZ, the two LM324 op amps, are oriented differMAY 1992 81 PARTS LIST FOR IR MODEL TRAIN CONTROLLER Case & hardware 1 plastic instrument case, 260 x 190 X 80 1 aluminium front panel 1 Dynamark front panel label, 250 x 75mm 1 M2165 60VA transformer 1 piece of 1.5mm gauge aluminium, 120 x 165mm 1 piece of 0.6mm gauge aluminium, 80 x 60mm 1 MU45 1mA meter 1 meter scale, 51 x 41 mm 9 5mm LED bezels 1 16mm nylon bushing 1 1MQ linear pot (VR4) 1 15mm diameter knob 1 9.5mm nylon cable clamp 1 3-way mains terminal block 1 cordgrip grommet for mains cord 1 panel mount 3AG fuse holder 1 1A 3AG fuse 2 solder lugs 2 panel mount banana sockets 1 12V buzzer 6 4BA 9mm Nylon screws plus nuts 4 6mm standoffs Wire & cable 1 mains cord with moulded 3-pin plug 1m 5-way rainbow cable 400mm 4-way rainbow cable 400mm brown medium duty hookup wire 400mm blue medium duty hookup wire 150mm blue mains rated wire 400mm brown mains rated wire 200mm green/yellow mains (earth) wire 200mm red light duty hookup wire 200mm black light duty hookup wire 200mm green light duty hookup wire 200mm red medium duty hookup wire 200mm yellow medium duty hookup wire 200mm blue medium duty hookup wire Miscellaneous Tinned copper wire , solder, 82 SILICON CHIP screws, nuts, self tapping screws, heatshrink insulating tubing, etc. Pulse power board 1 PC board, code SC91488, 117 x 125mm 2 8-way PC board mount screw connectors 1 6-way PC board mount screw connector 2 100kQ miniature vertical trim pots (VR1, VR2) Semiconductors 2 LM324 quad op amps (IC1, IC2) 1 4093 quad Schmitt NAND gate (IC3) 1 4049 hex inverter buffer (IC4) 2 BD650 PNP Darlington transistors (01 , 02) 2 BD649 NPN Darlington transistors (03, 04) 3 BC547 NPN transistors (05, 06, 08) 1 BC558 PNP transistors (07) 1 7812 12V 3-terminal regulator 5 1N914, 1N4148 signal diodes (D1-D5) 4 1N5404 3A diodes (D6-D9) 1 5mm bicolour LED (LED1) 1 5mm red LED (LED2) Capacitors 2 2200µF 25VW PC electrolytic 1 47µF 16VW PC electrolytic 1 10µF 16VW PC electrolytic 1 4.7µF 16VW PC electrolytic 1 2.2µF 25VW PC electrolytic 1 2.2µF 16VW PC electrolytic 2 0.1 µF MKT polyester or greencap 1 0.01 µF MKT polyester or greencap Resistors (0.25W or 0.5W, 1 560kQ 1 220kQ 2 120kQ 5 100kQ 1 27kQ6 1 22kQ1 2 15kQ1 1%, 7mm body) 5 10kQ 1 8.2kQ 2 5.6kQ 6 2.2kQ 1kQ 100Q 0.1Q 5W Transmitter board 1 plastic case, 68 x 130 x 43mm 1 PC board, code SC15204922, 88 X 57 1 front panel label, 63 x 125mm 4 black PC board mount momentary switches 4 white PC board mount momentary switches 1 grey PC board mount momentary switch 1 red PC board mount momentary switch 1 216 9V battery 1 216 9V battery clip 4 6mm standoffs 4 2mm x 20mm countersunk screws 12 2mm nuts 4 2mm washers 1 160mm-length 0.8mm tinned copper wire 1 CSB615A 615kHz Murata ceramic resonator (X1) Semiconductors 1 MV500 Plessey remote control transmitter (IC1) 1 BC338 NPN transistor (01) 1 B0140 PNP transistor (Q2) 2 COY89A, LD271 infrared LEDs (LED1, LED2) Capacitors 1 220µF 16VW PC electrolyfic 2 100pF ceramic Resistors (0.25W or 0.5W, 1%, 7mm body) 1 10kQ 1 100Q 1 1kQ 1 2.2Q 1 820Q lnfrared receiver board 1 PC board, code SC15204921, 140x98mm 1 CSB615A 615kHz Murata ceramic resonator 1 220kQ miniature horizontal trimpot (VR5) 1 10kQ miniature horizontal trimpot (VR3) 1 2.2kQ miniature horizontal trimpot (VR6) Semiconductors 1 SL486 Plessey infrared receiver amplifier (IC5) 1 MV601 Plessey remote control receiver (IC6) 1 4051 8-channel analog mutiplexer (IC?) 1 4066 quad analog switch (IC8) 1 LF351, TL072 dual FET input op amp (IC9) 3 4013 dual D flipflops (IC10,IC11,IC12) 2 BO681 NPN Darlington transistors (09, 010) 4 BC338 NPN transistors (011014) 1 BP104, BPW50 infrared detector diode (IRD1) 7 1N4148, 1N914 signal diodes (D1 0-D17) 5 1 N4002 1A rectifier diodes (D18-D22) 3 12V 400mW zener diodes (ZD1-ZD3) 2 6.8V 400mW zener diodes (ZD4-ZD5) 1 7905 5V negative regulator 7 5mm red LEDs (LED3-LED9) 00 00 "f ,... I en Capacitors 1 68µF 16VW PC electrolytic 1 22µF 16VW PC electrolytic 3 10µF 16VW PC electrolytic 1 6.8µF 16VW PC electrolytic 1 2.2µF tantalum electrolytic 6 0.1 µF MKT po lyester 1 .022µF MKT polyester 1 .015µF MKT polyester 1 .0047µF MKT polyester 2 100pF ceramic Resistors (0.25W or 0.5W, 2 10Mn 5% 11 100kQ 1 47kQ 410kn 1 8.2kQ 1 4.7kn 1%, 7mm body) 3 2.2kQ 10 1kQ 1 3300 1 47Q 3 12Q Parts for hand controller (for testing pulse power board) 1 plastic case, 83 x 54 x 28mm 1 1 0kQ linear pot. (VR3) 1 1 MQ trimpot (VR4) 1 220kQ trimpot (VR5) 2 SPOT togg le switches (S1 ,S2) 1 piece of Veroboard (50 x 20mm) 1 6-way cable (to connect to pulse power board) u en ~ Fig.10: compare your etched PC board against this full-size artwork & correct any defects before mounting any of the parts. ently on the board (ie, they point in different directions). Testing Instead of now proceeding to assemble the infrared transmitter and receiver, we suggest that the pulse power board be assembled into the case, along with the power transformer, some of the LEDs and so on. We will assume that you have purchased the full kit so there will be no need to do any metalwork, although you may have to drill holes in the plastic instrument case - see Fig.11. In effect, you will initially be wiring up the complete project minus the receiver board. We will then show you how to wire up a simple hand control (the same as published in our April 1988 issue) so that you can put the pulse power board through its paces. The 60VA transformer is mounted on a metal plate in the lefthand side of the case. The metal plate (we used 20-gauge aluminium sheet) is then secured to the case using four of the integral plastic pillars in the base. A 3-way insulated terminal block is required to terminate the mains wiring to the power switch and transformer. The mains Earth (green/yellow) wire is terminated to a solder lug which is attached to the transformer mounting plate. The mains wires to the power switch and fuseholder should be fitted with heatshrink sleeving to prevent any accidental contact. When fitting the mains cord, make sure it is anchored to the rear panel of the case using a cordgrip grommet. Mount the pulse power board on the lid of the case with four screws and nuts. We used nylon screws for this job since they are safer and the screw heads are less noticeable on the lid. Lay the lid, with the pulse power board fitted to it, to the right of the base and run the necessary wiring. The two transformer secondary windMAY 1992 83 Fig.11: this diagram is provided to enable you to initially install the pulse power board, power transformer & mains wiring. The pulse power board can then be tested with a hand-held throttle (see Fig.9). The installation of the receiver PC board & the rest of the wiring will be described next month. PULSE POWER PCB ON l:ASE LIO 11 ALUMIN IUM FRONT PA~NEL LED7 A - PLASTIC REAR PANEL 6 5 - )A 5 pf-A TRACK OUiPUT TERMINALS INFRAREO RECEIVER PCB p=ol LEDB A I LED9 ~ K L~ f~ 4-~A 1~1/1 K 2 LED1 K I OUTPUTS TO RELAYS ALUMINIUM BASE PANEL F1 84 SILICON CHIP LEO4 . . LE~) -e ~ 1.,,.,.. A. ~ ~~ A GROMMETG e 3 ~===================~s1 1 6 , r~ . The run & stop inertia adjustment pots (VR4 & VR5) in the hand-held controller are mounted on a small piece of Veroboard. Note: these pots are optional for testing purposes & could be replaced by wire links. ings are connected in parallel (0V to 0V and 12V to 12V) before being connected to the relevant points on the connector strip. You can also wire in the overload buzzer and the output (track) leads which connect to binding post terminals on the rear panel. The LEDs can be connected directly to the connector strip at this stage, leaving the permanent wiring till later. Handheld control To test the pulse power board, you will need a handheld control and we have shown one wired up on Veroboard in Fig.9. It is wired up to Terminals 1-6 on the pulse power board. Switch Sl functions as a Run/Stop switch while switch S2 provides forward and reverse. VR3 becomes the main speed control, VR4 the inertia control, and VR5 the braking control. However, don't wire in the control until you have made the following voltage checks. Powering up Having completed the wiring, check your work carefully and then apply power. A number of voltage checks should now be made. To make these easier, orient the pulse power board in the same direction as the diagram of Fig.8 and have last month 's issue open at the circuit diagram on page 70. That way, it will be easier to find your way around the board. Switch your multimeter to the 20V DC range and check that + 17V is present at the IN terminal of the 3terminal regulator (you can pick it up at the end of the adjacent 2.2kQ resistor) and at the emitters of Ql and Q2. Depending on the incoming mains voltage, this measurement is likely to be anywhere between+ 17V and +21 V, or even a little more. TABLE 1 IC Pins Voltage IC1 1, 2, 3 +1.2V IC1 5,6, 7 +4.8V (triang le waveform at pin 9, square wave at pin 7 IC1 8, 9, 10 Same as wiper of VR1 IC1 12, 13, 12 Same as wiper of VR2 IC2 1 +11V IC2 2 ov IC2 3 +0.6V IC2 5 10.1V IC2 6 +9.8V IC2 7 +12V IC2 8,9, 10 Close to 0V IC2 12 +1 .8V IC2 13 Same as pin 6, IC1 IC2 14 ov Now check for +12V at the output of the 3-terminal regulator and on each of the supply pins of the ICs: pin 4 of ICl and IC2, pin 1 ofIC4, and pin 14 of IC3. Again, the actual voltage will vary between +ll.4V and +12.6V, depending on the actual 7 812 (or LM340T-12) used. The voltages around !Cl and IC2, as shown in Table 1, should now be checked with the handheld throttle disconnected. These voltages are "ballpark" figures only but should be a good guide to see that things are working. Now you can wire in the handheld control and check that the voltages at pins 3 and 4 swap from high to low or vice versa when the forward/reverse switch is operated. Check that the voltages at pins 6, 7, 9, 10, 11, 12, 14 & 15 also change state when the forward/reverse switch is operated. Now connect your multimeter across the output terminals of the controller and wind the throttle control up to maximum. Adjust VRl on the pulse power board so that the voltage is 12V (or whatever is the maximum recommended operating voltage for your locos). Now rotate the throttle to the minimum and adjust VR2 for an output of 1.5V (you will want to "fine tune" this minimum setting once you start operating trains). Now note that the polarity of the output voltage changes when you operate the forward/reverse switch and that the colour of the track LED changes (from red to orange or vice versa). Now wind the throttle to about the half-way mark and briefly short the output terminals. The overload LED should light and the buzzer should sound. You can also listen to the operation of the controller by connecting a loudspeaker to the output terminals via a l00Q resistor. (Don't connect it directly otherwise you'll probably blow the loudspeaker). At low throttle settings, the loudspeaker will have a thin, reedy sound. At higher settings, the sound will be louder but more mellow. With all those checks made, you can now run trains if you like. After all, you probably want a break from soldering at this stage. Next month, we shall complete the project by presenting the assembly details of the infrared transmitter and receiver. SC MAY 1992 85 AMATEUR RADIO BY GARRY CRATT, VK2YBX Receiving weather satellite signals; Pt.2 Last month, we looked at the polar orbiting weather satellites and discussed the equipment necessary to receive and decode images transmitted by them. This month, we look at the SHF transmissions which originate from the Japanese GMS-4 satellite. The Japanese GMS-4 satellite is located in geostationary orbit at 140° east. This satellite transmits enhanced images on a frequency of 1691MHz, requiring the use of microwave techniques for good quality reception. When one considers the minute signal levels reaching the Earth's surface (typically .05µV), it becomes apparent that considerable care must be taken to receive and display weather images from this satellite. The GMS satellite uses a deviation of ±126kHz and so the receiver must have a minimum IF bandwidth of 260kHz. This increased bandwidth means that the received noise is about 10 times larger in amplitude than from a VHF polar orbiting satellite having a deviation of ±18kHz. In order to recover useable signals , the antenna must be capable of pro- This image from the Japanese GMS-4 satellite clearly shows the cyclone that eventually crossed the Queensland coast during March 1992. 86 SILICON CI-IIP viding sufficient gain between the incoming signal level of -134dBm and the typical receiver sensitivity of -1 lOdBm. This equates to a gain of 26dB, requiring a dish having a diameter of at least 1. 5 metres. Such dishes are often available from satellite TV dealers, who often have damaged units of no use at 12GHz but still quite useable at the frequency of the GMS satellite. Fig. l shows the gain that can be expected from dishes of various _diameters. The path loss between spacecraft and Earth at 1691MHz is approximately 188dB and as the output signal from the satellite is 5W (+37dBm), and the gain of the spacecraft antenna is around 17dBi, the calculated signal at the ground is -134dBm. Receiver requirements To obtain a good signal, the receiver should also have a noise figure of around 1.5-ZdB. A popular configuration is to use a microwave mixer and local oscillator chain feeding a VHF receiver. Particular care must be taken to ensure that the local oscillator is kept as stable as possible: it will be oscillating at about 1500MHz, to produce an IF of 137MHz (for example), and any drift in the oscillator will be multiplied by 15 or so (assuming the oscillator runs a 20MHz crystal). Thus, a frequency offset of lkHz will become a shift of 75kHz at 1500MHz. The most important parameter of the GMS receiving system is the IF bandwidth of the receiver. Some weather satellite enthusiasts have attempted to use scanning receivers for the purpose, as they cover the SHF frequency range. However, these receivers have a wideband FM bandwidth of 150-lB0kHz, causing poor signal-to-noise ratio and severe limiting of greyscale resolution. A correctly ing this distance for maximum signal. Fortunately, for those without the resources or time to construct a GMS system, specially designed and prebuilt components .are available. PH Communications - phone (07) 264 1575 - produces a built up GMS receiver, downconverter and dipole feed system. They also produce a suitable 1.7GHz LNA (low noise amplifier) for those who think they need it. S.CISAT Products are finalising a complete GMS receiver/downconverter. QUORUM Communications (address details in last month's issue) produce a suitable downconverter, model SDC16918. Polar orbiters Taken from one of the NOAA polar orbiting satellites, this infrared image of the United Kingdom shows quite a lot of detail, including many small towns. designed receiver must have an IF bandwidth of 260-280kHz. Unfortunately, most receiver designs featured in overseas magazines are suitable only for METEORSAT or GOES satellites, which have an IF bandwidth of 40kHz. With this kind of signal improvement over GMS transmissions (+8.25dB), signals can be heard on four phased Yagi antennas. While GMS transmissions can be heard using such equipment, pictures cannot be produced, due to the reduced signal levels. As 1691MHz is a frequency used exclusively for weather satellite transmissions, commercial feedhorns for this frequency are not readily available. Because the efficiency of the dish is related to the type of feedhorn arrangement used, the design of this component is also very important. The first step towards constructing a suitable feedhorn is to determine the focal point of the dish, so that the feedhorn can be correctly positioned. This can be calculated using the formula F = D2 /2c, where F is the focal point, D is the diameter and c is the depth of the dish. Designs for "coffee can" feedhorns can be found in the ARRL Antenna Book, and Jessop's VHF UHF Manual. A table in the latter book shows both the 3dB and lOdB beam width required for various values of F/D. This table enables constructors to select a suitable feedhorn design, once the F/D of the dish is known, ensuring that the dish is fully illuminated and operating at peak efficiency. As an example, a feedhorn suitable for a dish having an F/D ratio of 0.56 can be constructed using a 12cm long, 18cm wide can, containing a quarter wavelength monopole (3cm), mounted 3cm from the rear of the tube. The focal point is measured from the inside centre of the dish to the inside edge of the feedhorn. As is the case with all microwave receiving systems, the feed must be rotated to the correct satellite polarity, corresponding to maximum signal level, and the focal point should also be fine tuned by carefully adjust- Fig.1: Dish Diameter vs. Gain Diameter Gain (dBi) 0.6 18 1.2 24 1.5 26 1.8 27.5 2.0 29 2.4 30 3.0 32 There is yet another mode of transmission used by the polar orbiting weather satellites described in our first article. These polar orbiters produce extremely high resolution pictures and the data is transmitted on frequencies similar to GMS. In the case of NOAA 9 & 11, this frequency is 1707MHz. For NOAA 10 it is 1698MHz. Data is collected from spacecraft instruments such as the Advanced Very High Resolution Radiometer (AVHRR), the Operation Vertical Sounder (TVOS), the Space Environment Monitor (SEM), the Data Collection System (DCS) and the spacecraft telemetry system. The subject of HRPT signal reception is quite complex and extremely interesting. Dedicated newsletters for enthusiasts are available, such as the Journal of the Environmental Satellite Amateur Users Group. This is published by the Dallas Remote Imaging Group, 4209 Meadowdale Drive, Carrollton, TX 75010 USA. Several copies perused in our office indicate that this newsletter contains a high level of quality information. Further reading (1) "High Resolution Weather Satellite Pictures," M. L. Christieson, Wireless World December 1981 and January 1982. (2) "Tracking Low Earth Orbit Satellites At LIS Band", "Break In" NZART publication, March 1989. Acknowledgment I would like to thank Mr Brian Buckingham and Mr Fred Lehner for their time and assistance in supplying background information. SC MAY 1992 87 July 1988: Stereo Control Preamplifier, Pt.2; Fitting A Fuel Cut-Off Solenoid; Booster For TV & FM Signals ; Th e Discolight Light Show, Pt.1; Tone Burst Source For Amplifier Headroom Testing ; What Is Negative Feedback, Pt.3; Amplifier Headroom - Is It A Con? August 1988: Building A Plasma Display; Universal Power Supply Board ; Remote Chime/Doorbell; High Performance AC Millivoltmeter, Pt.1; Discolight Light Show, Pt.2 ; Getting The Most Out 01 Nicad Batteries; Data On Insulated Tab Triacs. September 1988: Hands-Free Speakerphone; Electronic Fish Bite Detector; High Performance AC Millivoltmeter, Pt.2; Build The Vader Voice ; Motorola MC34018 Speakerphone IC Data; What Is Negative Feedback, Pt.4. October 1988: Stereo FM Transmitter (Uses Roh m BA1404) ; High Performance FM Antenna ; Matchbox Crystal Set; Electronic House Number; Converting A CB Radio To The 28MHz Band ; Queensland's Powerful Electric Locomotives. November 1988: 120W PA Amplifi er Modul e (Uses Mosfets) ; Poor Man's Plasma Display; Automotive Night Safety Light; Adding A Headset To Th e Speakerphone; How To Quieten The Fan In Your Computer; Screws & Screwdrivers, What You Need To Know ; Diesel Electric Locomotives. December 1988: 120W PA Amplifier (With Balanced Inputs), Pt.1; Diesel Sound Generator; Car Antenna/Demiste r Adaptor ; SSB Adaptor For Shortwave Receivers ; Why Diesel Electrics Killed Off Steam ; Index to Volume 1. January 1989: Line Filter For Computers; Ultrasonic Proximity Detector For Cars ; 120W PA Amplifier (With Balanced Inputs) Pt.1; How To Service Car Cassette Players; Massive Di esel Electrics In The USA; Marantz LD50 Loudspeakers. May 1989: Electronic Pools/Lotto Selector ; Synthesised Tom-Tom; Biofeedback Monitor For Your PC ; Simple Stub Filter For Suppressing TV Interference; LED Message Board, Pt.3; Electronics For Everyone - All About Electrolytic Capacitors. February 1989: Transistor Beta Tester; Minstrel 2-30 Loudspeaker System ; LED Flasher For Model Railways (uses LM3909); Build A Simple VHF FM Monitor (uses MC3362), Pt.1 ; Lightning & Electronic Appliances ; Using Comparators to Detect & Measure. June 1989: Touch-Lamp Di mmer (uses Siemens SLB0586) ; Passive Loop Antenna For AM Radios; Universa l Temperature Controller; Understanding CA O Probes; LED Message Board, Pt.3. March 1989: LED Message Board, Pt.1; 32-Band Graphic Equaliser, Pt.1 ; Stereo Compressor For CD Players; Amateur VHF FM Monitor, Pt.2; Signetics NE572 Compandor IC Data; Map reader For Trip Calculations ; Electronics For Everyone Resistors. Apri l 1989: Auxiliary Brake Light Flasher; Electronics For Everyone: What You Need to Know About Capacitors; Telephon e Bell Monitor/Transmitter ; 32-Band Graphic Equaliser, Pt.2 ; LED Message Board, Pt.2. July 1989: Exhaust Gas Monitor (Uses TGS812 Gas Sensor); Extension For The Touch-Lamp Dimmer; Experimental Mains Hum Sniffers ; Compact Ultrasonic Car Alarm ; NSW 86 Class Electric Locomotives. August 1989: Build A Baby Tower AT Computer; Studi o Series 20-Band Stereo Equaliser, Pt.1 ; Garbage Reminde r - A 7-Day Prog ramm able Tim er; Introducti on To Stepper Motors; GaAsFet Pream plifier For The 2-Metre Band ; Modern 3Phase Electric Locomotives. September 1989: 2-Chip Portable AM Stereo Use this han~y form to order your back copies Please send me a back issue for: D October 1988 D November 1988 D March 1989 0 April 1989 D August 1989 O September 1989 D January 1990 0 February 1990 O June 1990 D July 1990 O November 1990 D December 1990 D April 1991 0 May 1991 O September 1991 D February 1992 O October 1991 0 March 1992 ., O August 1988 D Jan uary 1989 O June 1989 o Novembe r 1989 D April 1990 D September 1990 D February 1991 0 July 1991 D December 1991 0 O O O O July 1988 December 1988 May 1989 October 1989 March 1990 o August 1990 D January 1991 o June 1991 D November 1991 0 April 1992 Enclosed is my cheque/money order for $___or please debit my: O Bankcard -l ---, O September 1988 D February 1989 0 July 1989 O December 1989 0 May 1990 0 October 1990 O March 1991 D August 1991 D January 1992 D Visa Card o Master Card $5.00 each (includes p&p) . Overseas orders add $1 each for postage. NZ orders are sent air mail. Signature _ _ _ _ _ _ _ _ _ _ _ _ _ Card expiry date_ _ /_ _ Name _ _ _ __ __ __ _ _ _ _ _ _ _ _ _ _ _ __ _ _ _ _ Street _ _ _ __ _ _ _ _ __ _ _ _ _ _ __ __ __ _ __ Suburb/t o w n - - - - - - ~_ _ _ _ _ _ _ Postcode _ _ _ _ __ L __ ________ __ _ 88 SILICON CH IP ___ ______ _ _ __ _ Detach and mail to : SILICON CHIP PUBLICATIONS PO BOX 139 COLLAROV BEACH NSW 2097 l Or call (02) 979 5644 & quote yo ur credit card details. Fax (02) 979 65o3 _ _ _ _ _ _ _ _ _ _ _ _ J I_ _ Radio (Uses MC 13024 and TX7376P) Pt.1 ; AlarmTriggered Telephone Dialler; High Or Low Fluid Level Detector; Simple DTMF Encoder; Studio Series 20-Band Stereo Equaliser, Pt.2; Auto-Zero Module for Audio Amplifiers (Uses LMC669). Protection Switch For Power Supplies; A Speed Alarm For Your Car; Design Factors For Model Aircraft; Fitting A Fax Card To A Computer; What To Do When Your Computer Goes Bung, Pt.2. TV; 4-Channel Lighting Desk, Pt.1; 13.5V 25A Power Supply For Transceivers; Active Filter For CW Reception; Electric Vehicle Transmission Options; Tuning In To Satellite TV, Pt.1. July 1990: Digital Sine/Square Generator, Pt.1 (Covers 0-500kHz); Burglar Alarm Keypad & Combination Lock; Simple Electronic Die; Low-Cost Dual Power Supply; Inside A Coal Burning Power Station; What To Do When Your Computer Goes Bung, Pt.3 ; Weather Fax Frequencies. July 1991: Battery Discharge Pacer For Electric Vehicles; CD Error Analyser, Pt.1; Loudspeaker Protector For Stereo Amplifiers; 4-Channel Lighting Desk, Pt.2; How To Install Multiple TV Outlets, Pt.2; Tuning In To Satellite TV, Pt.2; PEP Monitor For Transceivers August 1990: High Stability UHF Remote Transmitter; Universal Safety Timer For Mains Appliances (9 Minutes); Horace The Electronic Cricket; Digital Sine/Square Wave Generator, Pt.2; What To Do When Your Computer Goes Bung, Pt.4. August 1991: Build A Digital Tachometer; Masthead Amplifier For TV & FM ; PC Voice Recorder; Error Analyser For CD Players, Pt.2; Tuning In To Satellite TV, Pt.3; Installing Windows On Your PC; Step-By-Step Vintage Radio Repairs. September 1990: Music On Hold For Your Telephone; Remote Control Extender For VCRs; Power Supply For Burglar Alarms; Low-Cost 3Digit Counter Module; Simple Shortwave Converter For The 2-Metre Band. September 1991: Studio 3-55L 3-Way Loudspeaker System; Digital Altimeter For Gliders & Ultralights, Pt.1; Build A Fax/Modem For Your Computer; The Basics Of AID & D/A Conversion; Windows 3 Swapfiles, Program Groups & Icons; How Glass-Mount antennas Work. October 1990: Low-Cost Siren For Burglar Alarms; Dimming Controls For The Discolight; Surfsound Simulator; DC Offset For DMMs; The Dangers of Polychlorinated Biphenyls; The Bose Lifestyle Music System; Using The NE602 In Home-Brew Converter Circuits. October 1991: Build A Talking Voltmeter For Your PC, Pt.1; SteamSound Simulator Mk.II; Magnetic Field Strength Meter; Digital Altimeter For Gliders & Ultralights, Pt.2; Getting To Know The Windows PIF Editor. November 1990: Low-Cost Model Train Controller; Battery Powered Laser Pointer; A Really Snazzy Egg Timer; 1.5V To 9V DC Converter: How To Connect Two TV Sets To One VCR; Introduction To Digital Electronics; Simple 6Metre Amateur Transmitter. November 1991: Colour TV Pattern Generator, Pt.1 ; Battery Charger For Solar Panels; Flashing Alarm Light For Cars; Digital Altimeter For Gliders & Ultralights, Pt.3; Build A Talking Voltmeter For Your PC, Pt.2; Error Analyser For CD Players Pt.3; Modifying The Windows !NI Files. December 1989: Digital Voice Board (Records Up To Four Separate Messages); UHF Remote Switch; Balanced Input & Output Stages; Data For The LM831 Low Voltage Amplifier IC; Install A Clock Card In Your PC; Index to Volume 2. December H/90: DC-DC Converter For Car Amplifiers; The Big Escape - A Game Of Skill; Wiper Pulser For Rear Windows; Versatile 4-Digit Combination Lock; 5W Power Amplifier For The 6Metre Amateur Transmitter; The Great Green CD Pen Controversy; Index To Volume 3. December 1991: TV Transmitter For VCRs With UHF Modulators; Build An lnfrared Light Beam Relay; Compact Solid-State Laser Pointer; Build A Colour TV Pattern Generator, Pt.2; The Miracle Piano Teaching System; Windows 3 & The Dreaded Unrecoverable Application Error. January 1990: High Quality Sine/Square Oscillator; Service Tips For Your VCR ; Speeding Up Your PC; Phone Patch For Radio Amateurs; Active Antenna Kit ; Speed Controller For Ceiling Fans; Designing UHF Transmitter Stages. January 1991: Fast Charger For Nicad Batteries, Pt.1; The Fruit Machine; Two-Tone Alarm Module; Laser Power Supply; LCD Readout For The Capacitance Meter; How Quartz Crystals Work; The Dangers When Servicing Microwave Ovens. January 1992: 4-Channel Guitar Mixer; Adjustable 0-45V 8A Power Supply, Pt.1; Baby Room Monitor/FM Transmitter; Automatic Controller For Car Headlights; Experiments For Your Games Card; The GPS Satellite Navigation System. February 1990: 16-Channel Mixing Desk; High Quality Audio Oscillator, Pt.2; The Incredible Hot Canaries; Random Wire Antenna Tuner For 6 Metres; Phone Patch For Radio Amateurs, Pt.2 ; PC Program Calculates Great Circle Bearings. · February 1991: Synthesised Stereo AM Tuner, Pt.1; Three Inverters For Fluorescent Lights; LowCost Sinewave Oscillator; Fast Charger For Nicad Batteries, Pt.2; How To Design Amplifier Output Stages; Tasmania's Hydroelectric Power System. February 1992: Compact Digital Voice Recorder; SO-Watt/Channel Stereo Power Amplifier; 12VDC/ 240VAC 40-Watt Inverter; Adjustable 0-45V 8A Power Supply, Pt.2; The Mobile Telephone Revolution; Designing A Model Speed Controller. March 1990: 6/12V Charger For Sealed LeadAcid Batteries; Delay Unit For Automatic Antennas; Workout Timer For Aerobics Classes; 16Channel Mixing Desk, Pt.2; Using The UC3906 SLA Battery Charger IC. March 1991: Remote Controller For Garage Doors, Pt.1; Transistor Beta Tester Mk.2; Synthesised AM Stereo Tuner, Pt.2 ; Multi-Purpose 1/0 Board For PC-Compatibles; Universal Wideband RF Preamplifier For Amateurs & TV; A Look At The Config.Sys & Ansi.Sys Files. March 1992: TV Transmitter For VHF VCRs; Studio Twin Fifty Stereo Amplifier, Pt.1; Thermostatic Switch For Car Radiator Fans; Telephone Call Timer; Updating The Resistor/Capacitor Scene; Coping With Damaged Computer Directories. October 1989: Introducing Remote Control ; FM Radio Intercom For Motorbikes (Uses BA 1404 & TDA?000) Pt.1; GaAsFet Preamplifier For Amateur TV; 1Mb Printer Buffer; 2-Chip Portable AM Stereo Radio, Pt.2; Installing A Hard Disc In The PC; A Look At Australian Monorails. November 1989: Radfax Decoder For Your PC (Displays Fax, RTTY and Morse) ; Super-Sensitive FM Wireless Microphone; FM Radio Intercom For Motorbikes, Pt.2; 2-Chip Portable AM Stereo Radio, Pt.3; Floppy Disc Drive Formats & Options; The Pilbara Iron Ore Railways. April 1990: Dual Tracking ±50V Power Supply; VOX With Delayed Audio ; Relative Field Strength Meter; 16-Channel Mixing Desk, Pt.3; Active CW Filter For Weak Signal Reception; How To Find Vintage Radio Receivers From The 1920s. May 1990: Build A 4-Digit Capacitance Meter; High Energy Ignition For Cars With Reluctor Distributors; The Mazzie CW Transceiver; Waveform Generation Using A PC , Pt.3; 16-Channel Mixing Desk, Pt.4; What To Do When Your Computer Goes Bung, Pt.1. June 1990: Multi-Sector Home Burglar Alarm ; Low-Noise Universal Stereo Preamplifier; Load April 1991: Steam Sound Simulator For Model Railroads; Remote Controller For Garage Doors, Pt.2; Simple 12/24V Light Chaser; Synthesised AM Stereo Tuner, Pt.3; A Practical Approach To Amplifier Design, Pt.2; Playing With The Ansi.Sys File ; FSK Indicator For HF Transmissions. May 1991: Build A DTMF Decoder; 13.5V 25A Power Supply For Transceivers; Stereo Audio Expander; Fluorescent Light Simulator For Model Railways ; How To Install Multiple TV Outlets, Pt.1 ; Setting Screen Colours On Your PC. June 1991: A Corner Reflector Antenna For UHF April 1992: lnfrared Remote Control For Model Railroads; Differential Input Buffer For CROs; Studio Twin Fifty Stereo Amplifier , Pt.2; Understanding ComputEl,r Memory; Switching Frequencies in Model Speed Controllers; Aligning Vintage Radio Receivers, Pt.1. PLEASE NOTE: All issues from November 1987 to June 1988 are now sold out. All subsequent issues are presently in stock. For readers wanting articles from sold-out issues, we can supply photostat copies (or tearsheets) at $5.00 per article, including postage. When supplying photostat articles or back copies, we automatically supply any relevant Notes & Errata at no extra charge. MAY 1992 89 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. Transistor replacements On the Brake Light Flasher Circuit (described in the April 1989 issue of SILICON CHIP), is there another transistor I can use instead of the BD645? I have catalogs from Altronics, Rod Irving, Dick Smith Electronics and Jaycar, and none of them list BD645. And in Fig. 2 of the article on the Car Antenna Adaptor (SILICON CHIP, December 1988), the photo shows two wires that come from the power to the circuit board, with (+)going to L2 and (-) is going to L1, but on the other side of the toroid it shows L1 going to (+), and L2 going to(-). Does it make any difference which wires go to the demister? Also in the text it specifies that the 75-ohm cable should have a 1.25mm central core. Most ofmy catalogs don't list the sizes of the central core of their 75-ohm cable and the largest size that is stated is 0. 95mm from DSE. Where can I get 75-ohm cable with a 1.25mm central core? Finally, the toroid core is specified as Neosid 28-042-31 F14 ferrite but I can't find that part in any of the Remote control extender I have constructed the remote control extender published in the September 1990 issue of SILICON CHIP but I have been unsuccessful in getting it to operate. The indicating LED does light up when the · remote controller of the VCR is operated, however the signal is not being received at the VCR end. Can you please help me with the following questions: (1) What should the output..voltage at pin 9 of the SL486 be when high? Using a multimeter, the voltage is 200m V when low and varies little when high. From data sheets, 90 SILICON CHIP catalogs I have. The closest I can find is a toroid core, size OD 44 x ID 24 x H 16.5mm, which is the type I bought. (O. M., Liverpool, NSW.) • In the Brake Light Flasher project you can replace the BD645 transistor with a BD649, which is available from Altronics in Perth for $2.65. This transistor is virtually identical to the BD645 except that it has a higher voltage rating. For the Car Antenna Adaptor project, we haven't tried the toroidal core you mentioned in your letter, however as the application is not all that critical, we cannot see why it wouldn't work. You can substitute 50-ohm coaxial cable for the 75-ohm type. A suitable type would be Dick Smith Cat. W2099. It does not make any difference which wires go to the demister. Current rating for solar battery charger I am after some more information concerning the "Battery Charger for Solar Panels" that appeared in the November 1991 edition. I am considering using the charger this voltage should be Vee (the supply voltage). I replaced this chip and the same results occurred. (2) What should the voltage be at the receiving end; ie, at the infrared LED? (3) The BPW50 chip has been replaced by a BP104. Is this OK? Your help would be appreciated. (B. M, Rockhampton, Qld). • The BPW50 can be replaced by a BP104 but you have replaced the SL486 unnecessarily as it was probably behaving normally. Some constructors are having low sensitivity problems with this unit. When re-transmitting an infrared remote control signal, the red acknowledge LED flashes to indicate with an SLA battery but one that requires a float voltage ofbetween 13.6V and 13.8V for standby use. It is intended to connect the charger's input to an automotive electrical system. The SLA battery I have draws a peak current of around 2A, which quickly dies away to a fraction of this as the battery charges. I wish to know the maximum continuous and maximum peak current the charger can supply, as this information does not appear anywhere in the article. I would also like to see a graph of load voltage against load current. Apart from this omission, the circuit would seem to be ideal for the intended application and, with the addition of a constant cur:..ent sink, could be used to charge nicads while in a mobile environment (eg, battery packs for hand held radios). Your thoughts and ideas on this application for the charger would be greatly appreciated. (W. ·S., Endeavour Hills, Vic). • The capacity of the circuit is about 2A, although this will depend more on the solar panel than the circuit components. It should be suitable for your SLA battery. It could also be reception of this signal, as you have found. However, the infrared LED (IRLED1) may not provide a satisfactory output for some or all of the remote control functions. This problem is caused by IC1 's AGC attack time being too short when used with some infrared remote controls. To solve this problem, the 0.15µF capacitor at pin 8 of ICl.should be changed to a larger value. Some experimentation may be required to find the best value, which should be in the range from 6.8µF to 22µF (use an electrolytic). The positive terminal of the capacitor connects to pin 8 of IC1 and the capacitor should be rated at 16VW or higher. used for nickel cadmium batteries provided you included a timer or some other means to avoid overcharging. Exhaust gas analyser would be a good project I am writing to enquire whether or not you may have considered publishing an exhaust gas analyser in your magazine. As a motoring enthusiast who likes to work on my own car, I often have wished for an exhaust gas analyser to set the mixture on the carburettor but sadly, commercial units cost many hundreds of dollars. These electronic units use infrared pickup devices, calibrated accordingly, or "hot wire" resistance devices. Perhaps even the sensing device in the exhaust gas detector project published in the July 1989 issue could be used? I'm sure this project would be very popular, as digital tacho/dwell projects for cars have been very popular too. (S. L., North Balwyn, Vic). • It would be relatively easy to develop a suitable circuit and, as you suggest, it could be based on a semiconductor gas sensor similar to that used in the exhaust gas detector featured in the July 1989 issue of SILICON CHIP. The big problem is how to calibrate the circuit. It must either be calibrated in a standard gas mixture or against a standard gas analyser. We don't have the solution to this problem, otherwise we would have published the circuit already. Improvements to the SLA battery charger I'd like to make a suggestion concerning Darren Yates' Sealed Lead Acid Battery Charger in the March 1990 issue. This turned out to be a terrific charger after ironing out some bugs: (1) figuring out the way voltage select switch S3 is hooked up; and (2) figuring out why the charge state LEDs would not behave. The person I assembled this charger for raised the possibility of damage to the charger through leakage from the battery when the unit was switched off with the battery still connected. I had a 24V relay lying around, so I connected the coil to the 24V DC that enters the board and the 'normally open' contacts to the positive lead running to the battery being charged. Sports coil does not give better spark I have built the High Energy Ignition System described in the Ap:dl 1988 issue of SILICON CHIP. On two occasions now it has failed. On the first occasion it blew the Dadington transistor, the IC and one of the polyester capacitors. On the second occasion, all the zener diodes had gone short circuit. Is there anything wrong with the design? My friend seems to think that it is because I am using a sports coil rather than the original coil fitted to the car. (A. K., Haberfield, NSW). • Your friend is dead right. If you use a sports coil with this circuit, you are bound to blow it up sooner or later. Because of the inbuilt dwell extension, the High Energy Ignition circuit causes consider- Thus, when the unit is off, the battery is isolated. This proved to be most effective and I intend to use it on all applicable projects in the future, as an additional safety feature to augment any diodes used for this purpose. The last point I'd like to make about this project is the mains switch only switching the Active line. Since the switches supplied with most kits are DPDTs, why not switch both Active and Neutral for safety? (P. B., Epping, NSW). • In view of some recent feedback on this project, we are looking to revise the circuit and present it again some time later this year. The main problem seems to be associated with the wiring of the switches and the use of LF347s as comparators but otherwise the original circuit was quite practical. There is no need to provide relay isolation, as the existing diodes in the circuit provide this feature. As far as the mains switching is concerned, there are no real advantages in switching both Active and Neutral, although we have on occasion used DPDT mains switches. On the one hand you can say that if Active and Neutral switching is included, the appliance will definitely be off when switched off. ably more current to flow through a standard ignition coil, thereby increasing available spark energy. A sports coil also draws considerably more current when fitted to a standard Kettering ignition system. Fitting a sports coil to an electronic ignition system with dwell extension is just asking for trouble as the current will be increased even further. No wonder you blew the Darlington transistor. The High Energy Ignition circuit gives more than enough spark energy with a standard coil. The only possible result of fitting a sports coil to it, apart from eventually blowing the system up, is that the spark plugs would be more quickly eroded and ultimately, would have to be replaced more often. Need we say more? Don't use a sports coil! However, we still regard the only safe mains appliance to work on as one with the mains plug pulled out of the wall socket. On the other hand, if only the Active is switched, the mains wiring is simpler and there are less chances of mistakes. Questions on amplifier design My questions concern the articles published in February and April 1991, "A Practical Approach to Amplifier Output Stage Design". With regards to the output stages, can more transistors (for each part of the amplifier) be connected in parallel to help provide more collector current? From what I can gather, this is used extensively in car amplifier design and surely beats having to use • TO-3 transistors (although they may handle a lot of power, they take up a lot of space, and their construction makes it harder to use fan cooling). A large number of car amplifiers use up to 14 transistors in each channel, and maintain a relatively small case. The author, David Eather, talks about transistors in common collector mode, and using emitter resistors for equal current sharing. Is the above essentially what he means? David Eather also discusses the use MAY 1992 91 Pulse current inIRLEDs With the infrared lightbeam relay published in the December 1991 issue, how was the value of the 15Q resistor in series with the LEDs calculated; ie, what were the values of forward voltage across the LEDs and what value of current was used? Also, can the infrared emissions be focussed with lenses and woµld the point of focus be much different to that of red light? In the same issue of SILICON CHIP there was a TV transmitter for VCRs. The output impedance of the transmitter was quoted as 75 ohms. Is this determined by L2 and the 220pF capacitor or is this a characteristic of the OM350? (D. A., Findon, SA). • The 15Q resistor in the light beam relay circuit was selected to give a peak current through the LEDs of between 300 and 400mA. Thi& gives a forward voltage across each LED of about 1.8V. The LEDs are able to pass a maximum repetitive peak current of 1A but only at very short duty cycles. Our circuit meets those requirements. You could focus the infrared light with lenses and thereby improve range and sensitivity. The point of focus would be little different to that for red light. As far as the TV transmitter is concerned, the output stage of the OM350 is designed to drive 75ohm loads. Its actual output impedance is, of course, much lower. of Mosfets in the output stage. Are ciated. (B. M., Giralang, ACT.) these similar to using bipolar transis• It is common practice to parallel tors? We covered Mosfets in electronoutput transistors to obtain greater ics as a "basic idea" course and from current capability in the output stages what I can see, they are a totally difof amplifiers. We have done this sevferent "can of worms". eral times with amplifiers published Any information on how these tran- in SILICON CHIP, the most recent exsistors are used in amplifier circuits ample being the 50 watt per channel would be greatly appreciated. Will stereo module featured in the Februthe driver transistors be affected by ary and March 1992 issues. the extra transistors used to handle The limit on how many output tranincreased collector current and if so, sistors can be connected in parallel is how can this be remedied? Can the set by the current capability of the DC-DC circuitry use this same techpreceding driver transistors but some nique , so that it can handle increased big commercial amplifiers we have current, in both the oscillator transisseen have had as many as six output tors (the final stage) and the DC regu- transistors in parallel, making a total lator? of 12 output transistors. Emitter resisDo transistor SOAR curves follow a tors are used to improve current sharing but the transistors need to be reahyperbolic function, with the limits being their maximum Vee and le? sonably well matched even so. When I was poking around in my Mosfets are a different ballgame mother's car one day, I noticed that since they are transconductance dethe back shelf had provision for three vices (ie, amps controlled by volts). 6 x 9-inch speakers and not long after, We featured an amplifier with Mosfets I thought of designing a circuit which in the output stages in our November would split a stereo signal into three · and December 1988 issues. channels: left only, that which is comThe SOAR (safe operating area) mon to both channels and a right only curve of a power transistor represents channel. a power derating at higher voltages There was a stereo enhancer project and as you have correctly surmised, (ETI-1405) which worked in a similar the curve is a hyperbola but with a manner..Instead of subtracting the censteeper slope than the hyperbola tre, L and R are isolated and added drawn from the transistor's nominal power rating. back later on. Any help with the questions I have We note your comments about car presented here will be greatly appreamplifiers using large numbers of tran92 SILICON CHTP sistors. However, car amplifiers do not just parallel a lot of output transistors to get sufficient power as this approach would still not give adequate power into loudspeakers with a nominal impedance of four ohms, or even two ohms. Commonly, car amplifiers use two amplifier stages in each channel and these drive the speakers in bridge mode. This means the maximum voltage to the speaker is doubled and hence the power is quadrupled (in theory). The bigger car amplifiers also incorporate a DC-DC inverter to boost the supply up and thus enable much more power to be developed. We are not keen about your 3-channel circuit concept. It really is not necessary. All stereo recordings have a substantial amount of signal common to both channels and since this is reproduced by both speakers, it avoids any "hole in the middle effect". How to magnetically shield loudspeakers How do you magnetically shield a loudspeaker case to stop it affecting the television nearby. (I hope to sit the TV on a homemade subwoofer enclosure). Keep up the great magazine! (H. P., San Remo , Vic). • As far as magnetically shielded loudspeakers are concerned, it is not the case or the chassis which needs shielding but the ferrite magnet. This is shielded, during manufacture, by a steel cup which i.s fitted over the magnet. In the 2ase of the more sensitive speakers with a bigger magnet structure, an additional magnet is interposed between the steel cup and the main magnet, to help cancel out any leakage field. We think that it would be difficult to satisfactorily shield an existing speaker unless you had the correctly designed hardware. Notes & Errata TV Transmitter for UHF VCRs, March 1992: the 12V supply connections shown on the overlay diagram of page 18 are reversed. Also the photo of the underside of the transmitter board is for the version described in December 1991. The components on the copper side of the board are not used in the UHF version. SC ORDER FORM BACK ISSUES* MONTH YEAR MONTH YEAR MONTH YEAR MONTH YEAR *Back issues are $A5 each (incl. postage). Overseas orders add $A 1 per issue for postage. BINDERS 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 SUBSCRIPTIONS 0 New subscription - month to start 0 Renewal - Sub. No. r------------7 0 RATES {please tick one) 2 years (24 issues) 0 0 0 0 0 Australia Australia with binder(s)* NZ & PNG (airmail) Overseas surface mail Overseas airmail I I I I I I I I I I Gift subscription ~ 1 year (12 issues) 0 0 0 0 0 $A84 $A105 $A130 $A130 $A240 $A42 $A53 $A65 $A62 $A120 *1 binder with 1-year subscription; 2 binders with 2-year subscription I I YOUR DETAILS Your Name (PLEASE PRINT) Address Daytime telephone number Postcode Enclosed is my cheque/money order $ 0 Bankcard Card No. 0 Visa Card or please debit my I GIFT SUBSCRIPTION DETAILS Month to start Message Gift for: Name I I I I I I I I I I I- (PLEASE PRINT) I Street I I I I Suburb/town I I I Postcode I State I IL _ _ _ _ _ _ _ _ _ _ _ _ _JI Signature 0 Master Card I I I I II I I I II I I I II I I I I Card expiry date I Phone (02) 979 5644 Fax (02) 979 6503 Mail coupon to: 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 Freepost 25 Silicon Chip Publications PO Box 139, Collaroy Beach 2097 No postage stamp required in Australia MAY 1992 93 MARKET CENTRE Cash in your surplus gear. Advertise it here in Silicon Chip. r----------------------- --, CLASSIFIED ADVERTISING RATES ANTIQUE RADIO 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 on the form 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. 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 & amplifiers. Open Sat. 10am-5pm; Sun. 12.30-5pm. 109 Cann St, Bass Hill, NSW 2197. Phone (02) 645 3173 BH or (02) 726 1613 AH. FOR SALE NEED A NEW GENERATION microcontroller? Program in Pascal, C, Turbo Basic, Quick Basic or 8088 Machine Language? The world's first MS-DOS pocket PC is what you need. Video cassette size Atari Portfolio $380. Lowest prices on accessories. For full info, send a 45c stamp to Don McKenzie, 29 Ellesmere Crescent, Tullamarine 3043. Phone(03)3386286. Enclosed is my cheque/money order for $_ _ _ _ or please debit my O Bankcard 0 Visa Card 0 Master Card XI I I Signature_ _ _ _ _ _ _ _ _ _ _ Card expiry date___/_ __ I I Name _ _ _ _ _ __ _ __ _ _ _ _ _ _ _ _ _ __ _ __ I I Street _ _ _ __ __ __ __ _ _ _ _ _ __ __ _ _ __ I I Suburb/town _ _ _ _ _ _ __ __ __ Postcode_ __ __ _ L _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ JI WEATHER FAX programs for IBM XT/ ATs *** "RADFAX2" $35 is a high resolution, shortwave weather fax, Morse & RTTY receiving program . Needs CGA, SSB HF radio & Radfax decoder. Also "RF2HERC", "RF2EGA" & "RF2VGA", same as RADFAX2 but suitable for Card No. 94 SILICON CHIP FIX-A-KIT KIT REPAIR & CONSTRUCTION 3 MONTHS WARRANTY ON REPAIRS 12 MONTHS WARRANTY ON CONSTRUCTION TECHNICAL ASSISTANCE . HVCAL ELECTRONICS Design, Manufacture & Re pair of Electronic Equipment (02) 633 5477 Old Reprinted Electrical Books Build a 40,000 Volt Induction Coil ............ $9 Electrical Designs (1901) ...................... $19 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 111 pp ... $27 Dr. Nikola Tesla - Complete Patents ...... $93 Tesla Coil Secrets .................................. $13 How to Build a Solar Cell That Works ...... $9 Photocells and Their Application ........... $20 1914 Catalog Electro Importing Co ....... $14 r Prices as at March 20, 1992 SIMM & SIP HONEYWELL INDUSTRIAL Chart Recorders. 12-inch. $25 each or $40 for two. Phone (02) 925 4434 or (02) 428 2273 AH. 16 CHANNEL MIXER: this is the prototype unit, as described in the February to April issues of SILICON CHIP. Complete and going. $850. Phone Leo Simpson on (02) 979 5644. BARGAIN PRICED ITEMS: twin (stereo) VU meters $3; 4OkHz ultrasonic transducers $3 per pair; used O.52mW HeNe laser heads and tubes $25. Dual element pyroelectric detector plus Fresnel lens plus white filter plus circuit, $9. Mains filters in IEC socket plus a varistor, $5. Used collimated 5mW IR CO--PROCESSORS 256Kb x 9 80ns 1 Mb x 9 (9 chip) 80ns 1Mb x 9 (3 chip) 80ns 4Mb x 9 80ns 1Mbxg 100ns 1Mbx8 80ns $17.00 $55.00 $53.00 $215.00 $50.00 $45.00 8087-1 80287-12 80287-20 80387SX20 80387IX33 80287XLT Intel AMO IIT IIT IIT Intel EXPANSION CARDS $130.00 $105.00 $130.00 $168.00 $250 .00 $150.00 DRAM 1Mbx4 1Mbx4 1Mbx4 1Mbx 1 414256 41256 41256 41464 4164 "- r 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) 661262. Hercules, EGA & VGA cards respectively. $35. *** "SATFAX" $45 is a NOAA, Meteor & GMS weather satellite picture receiving program. Uses EGA & VGA modes, needs EGA or VGA colour monitor & card, plus "WEATHER FAX" PC card. $45. *** All programs are on 5.25inch or 3.5-inch discs (state which) & include documentation. Add $3 postage. Only from M. Delahunty, 42 Villiers St, New Farm, 4004 Old. Phone (07) 358 2785. "I MEMORY, DISKS & PROCESSORS ~ St Zip PgZip Pg Dip 80ns 80ns 100ns 80ns 80ns 100ns $30.00 $30.00 $30 .00 $5 .75 $6.80 $1.90 $2.00 $2.60 $2.50 PELHAM TOSHIBA LAPTOP T1000SE T1600 T3100E T3100SX T3200 T5100 T5200 2Mb 2Mb 2Mb 2Mb 3Mb 2Mb 2Mb $265.00 $145.00 $145.00 $145.00 $236.00 $145.00 $155.00 LCS 866IN (AT) EMS 512-32Mb (SIMMS) OK $240.00 BOCARAM AT PLUS OKTO 8Mb $240.00 BOCARAM AT OK TO 2Mb $180.00 BOCA PS2 MCA OK TO BK $180.00 ($60 per Mb) COMPAQ 386-20, 386-25,386-20S, 386-S, 386-33 4Mb modules $345.00 4Mb boards $400.00 Sales Tax 20%. Overnight delivery. Credit cards welcome. 1st Floor, 100 Yarrara Road (PO Box 382), Pennant Hills 2120. Tel (02) 980 6988 Fax (02) 980 6991 " UNIDEN SCANNERS DON'T PAY MORE! 50XL RRP $299.95. Our price $211 10 memories, Lo-Hi VHF, UHF 10OXLT RRP $449.95. Our price $409 100 memories, Lo-Hi VHF, Air, UHF 200XLT RRP $549.95. Our Price $477 200 memories, Lo-Hi VHF, Air, UHF, 800 MHz All prices include delivery. Phone anytime today1 (03) 883 9535; Fax (03) 432 0716 ~ DIGI-CART DSP BOARD For 16-bit IBM compatibles. Broadcast quality 44.1 kHz/16 bit stereo audio with audio recorder software. $1599 + Tax Custom software service for applications available. PC Computers (08) 332 6513 36 Regent St Kensington SA TopCom Communications PO Box 336, Greensborough, Vic 3088. ~ TRANSFORMER REWINDS ALL TYPES OF TRANSFORMER REWINDS TRANSFORMER REWINDS - Reply Paid No.2, PO Box 438, Singleton, NSW 2330. Ph: (065) 761291 . Fax: (065) 761003. Direct CAD PCB design from your schematic, rough PCB,to ink plot negative for prototype or one-off in sing I e or doub I e sided with s ii k screens & .so I der resist. NC and photoplot options avai I able on floppies. 7 Phone <02)807 6916 or wr I te 0 ~ ~ .C ~ G . F . & M . Hugfies ~ PO Box 37, Ryde PCB ART NSW, 2112 0 JO - laser diode assemblies (collimator pens), $35; 1OnF/3kV disc ceramics, 10 for $12; used regulated 15kV 5OOµA EHT power supplies, $45; 1mW 800nm IR LEDs at 10 for $3.50. Oatley Electronics, PO Box 89, Oatley 2223. Phone (02) 579 4985. Fax (02) 570 7910. quantity prices. Limited supply. Oatley Electronics, PO Box 89, Oatley, NSW 2223. Phone (02) 579 4985. Fax (02) 570 7910. NEW CRO TUBES & VALVES: 1-inch electrostatic deflection, type number CV1522 - $35; 3-inch spiral PDA electrostatic deflection, type numbers DP1O-6 and 4VP7 - $44; 3-inch magnetic deflection (no yoke supplied) PDA, type numberCV223O-$25; mercury vapour rectifier value, type 866A/866-$5; pentode valve, type 6C6 - $5. All items in original cartons. Enquire about reduced INFRARE;D NIGHT VIEWER: Not a complete kit but just the absolute essentials- an IR image converter tube and a ready-made power supply. The supply has approximate dimensions of 105 x 56 x 37mm, draws approx. 35mA from a 9V battery, and can power any IR tube. The tube may have some blemishes but will function properly. Basic instructions are provided. Give-away at $150 for the MAY 1992 95 r-------------------------, l SILICON CHIP BINDERS These beautifully-made binders will protect your copies of SILICON CHIP. They feature heavy-board covers and are made from a distinctive 2-tone green vinyl that will look great on your bookshelf. Advertising Index Adilam Electronics ........ ..... ...... IFC All Electronic Components ........ 71 Altronics .... ....... ........ .......... .. 72-75 Antique Radio Restorations .. .... 94 Av-Comm ....................... ........ ... .. 8 Breakthrough Electronics ... .. ..... 25 * High quality. * Hold up to 14 issues David Reid Electronics ... ............. 3 Dick Smith Electronics ...... 9,27-29 * 80mm internal width. Emona Instruments ................ ... 55 Geoff Wood Electronics .............. 5 * SILICON CHIP logo printed in gold- G. F. & M. Hughes ................ .... . 95 coloured lettering on spine & cover. Harbuch Electronics ............... ... 42 Yes! Please send me ____ SILICON CHIP binder(s) at $A11.95 plus $A3 p&p each (NZ $A6 p&p). Hycal Instruments ............. ... 25,94 Enclosed is my cheque/money order for $_ _ _ _ or please debit my Jaycar Electronics ................ 45-52 □ Bankcard O Visa Card lcom Australia .. .... ...... .... ... ...... IBC J.V. Tuners .... .. .. ........................ 42 O Master Card Mark One Communications ..... . 39 Oatley Electronics .. .. ....... ... .. 57,95 Card No. L_____L_L___j____JI I~ '----'--'--..JI I~ L___j____J'-----.. JI ~I '---..J'-----..- - ' PC Computers .............. ... .. .... ... 95 PC Marketplace ... ... ... .. ....... ...... 21 Signature._ __ _ _ _ __ _ _ _ _ Card expiry date._ _ _ /_ __ Pelham ... .... .... ................... OBC,95 Name _ _ __ __ _ _ __ _ _ __ _ _ _ _ _ _ _ _ __ Peter C. Lacey Services ........... 40 Plough Book Sales .. ... ............... 95 Street - - - - -- - -- - - -- - -- - - - -- - - - Suburb/town _ _ _ _ _ _ _ _ _ _ _ _ Postcode_ _ _ _ __ Preston Electronics ................... 56 Protel Technology ... .................. 39 RCS Radio ... ............................. 54 Resurrection Radio .... .. .... ......... 71 SILICON CHIP PUBLICATIONS PO Box 139, Collaroy Beach, NSW 2097, Australia. Phone (02) 979 5644 Fax: (02) 979 6503. L _________________________ J Rod Irving Electronics .. .... .... 10-15 Rolec Pty Ltd .. .... .... .............. 66-67 Silicon Chip Back Issues ..... 88-89 Silicon Chip Binders ....... ........... 96 St Lucia ....................................... 7 pair. 75mm perspex IR filter, $16. Major cards accepted with phone & fax orders. Certified p&p for any or all the listed items: Australia $5; NZ (airmail) $10. Oatley Electronics, PO Box 89, Oatley, NSW 2223. Phone (02) 579 4985. Fax (02) 570 7910. Circuit Ideas Wanted Do you have a good circuit idea languishing in the ol ' brain cells? If so, why not sketch it out, write a brief description & send it to us We'll pay up to $60 for a really good circuit. So transfer your circuit to paper & send it to Silicon Chip Publications, PO Box 139, Collaroy Beach, NSW 2097. 96 SILICON CHIP WANTED TECS Electronics & Computers 61 Transformer Rewinds ... ........... .. 95 PERSON TO REPAIR Macintosh 512K power supply fault. Phone (03) 398 2486 (Bus) or (03) 742 6093 (AH) . TopCom Communications ........ . 95 CIRCUIT/MANUAL for Printed circuit boards for SILICON CHIP projects are made by: PC Boards National NV450A video recorder, TC2252 CTV. Phone (077) 72 8572 BH, (079) 52 3737 weekends. DISTORTION TEST SET wanted to buy. Must be auto-nulling and with instruction manuals. Can be Audio Precision , Sound Technology 170x, Hewlett Packard 339 or equivalent standard. If you have one to sell, please contact Leo Simpson on (02) 979 5644 with details and price. • Jemal Products, 5 Forge St, W~lshpool, 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, NSW 2207. Phone (02) 587 3491. SONY: SONY: LQQK LQQK PARENTS PARENTS ILLUSTRATED • D ENCYCLOPEDIA · 11 I) n LANGUAGES OF • Iii THE WORLD Why pay $1000's for books? Buy an entire educational centre plus so much more for $1140. NATIONAL GEOGRAPHIC ~ ~ Not only can this fantastic software package educate you and your children, it also can provide hours of entertainment. Learning can be difficult for many people, but with Interactive Educational Software, you interact with the computer, ask questions and watch the answers. Info on 200 animals, photos, range maps, motion clips essays and 155 animal vocalizations. rA MIXED-UP 1M The World Atlas brings the entire globe to your computer screen. This atlas, almanac and world fact book in one, gives you instant access to over 240 fully detailed, EGA/VGA colour maps and a huge database of international information. n MICROSOFT ~ 1111 REFERENCE LIBRARY~ '. . - GREAT FOR STUDENTS- MOTHER GOOSE* An interactive game designed to stimulate your child's imagination with full colour graphics and digitized sound, voices and music. WhatCDRoms are available? - The perfect reference tool for travellers, educators, business people, librarians and students of all ages. • D SOCIETY'S MAMMALS* WORLDATLAS* 1 A program which translates to and from Chinese, Danish, English, Finnish, French, German, Italian, Japanese, Norwegian, Spanish & Swedish. Allows retrieval of translations, dictionary entries and synonyms & then export to WP packages(Chinese and Japanese display only). Includes the full text of 18 dictionaries in 12 languages. Compton's Encyclopedia (from Brittanica) contains full text of 26 volumes, 9 million words, 32,000 articles, 1500 illustrations including sound and speech recording. Forget flipping through volumes, instead, follow key pathways on words and subjects - access information in the blink of an eye. Not only is this Software Educational - It's fun too! · ,· This indispensable collection of reference materials includes the American Heritage Dictionary, Roget's II Electronic Thesaurus, the World Almanac and Book of Facts, Bartlett's Familiar Quotations, and more- all on a single CD-ROM disc. Fm added efficiency, all reference volumes interface directly with more popular word processing programs. Over 1000 Rom products are available including SUBJECT ACCOUNTANTS AEROSPACE AGRICULTURE ART BIBLE STUDY BIOLOGY BIOMEDICINE CARDIOLOGY CHEMISTS CHESS CINEMA CIVIL ENG COMPUTERS DESKTOP PUBLISHING ELECTRICAL ENG . ENVIRONMENT GEOGRAPHY GEOLOGY HISTORY HORTICULTURE TITLE - Oiskrom Tax Law Database - Aerospace Database SUBJECT LAW LIBRARY -Agricola - Coafe's Art Review Impression ism - CD Word/The Bible Library - Biological Abstracts -Bibliomed - Bibliomed Cardiology Series - Excerpta Medica - Drugs & Pharmacology - Chess Datarom -Cinescan - Citis CD-ROM - Carousel/C-CD ROMiComputer Select - Clip Art (Various) - FT Business Graphics - lnspec On Disc. - Environme ntal Library - Countries of The World -Geovision Windows on the World - The Middle East Diary - The Plant Doctor MEDICINE MUSIC NURSING OCEANOGRAPHY PATENTS PEOPLE SCIENCE SPACE TRAVEL VETERINARY WILDLIFE GENERAL TITLE - Case Law, NSW, SA, TAS & VIC - Books in Print PlusfBNB on CD Rom - Business Periodicals - Cancer on DiscfConsult Medical -Posindex - Music Library Sound Recordings -Nurses Medical Partner - Aquatic Science -Automated Patent Search (us· - Biography Index · - Applied Science Library - Nasa Space Encyclopedia - Great Cities Of The World - The Merck Veterinary Manual - Wildlife & Fish Worldwide -Australia On a Disk - Best Encyclopedia-Grolier - Business Periodicals on Disk - Facts on File 1980-90 - Guinness Book of Records -Jane's All The World's Aircraft -Oxford English Dictionary ~-----------------~ COMPUTER REQUIREMENTS XT/AT Compatible, 512 Ram. DOS 3.1 or above hard disk drive. Recommended VGA Monitor & VGA adapter Mouse *Requires VGA (For PS2 MCA I/F card add $320) PACKAGE CONTENTS Sony external drive model CDU 7205U (which supports CD Rom mode 1 & 2 & Audio combined CD) Sony bus interface card (half card value $180) Software Collection (as detailed) PELHAM PTY LTD 1st Floor, 100 Yarrara Road, Pennant Hills 2120 Ph (02) 980 6988 Fax (02) 980 6991