December 1991 - Silicon Chip Online

Outer Front Cover
Contents
Publisher's Letter: Music and computers - a new way to learn
Feature: The Miracle Piano Teaching System by Darren Yates
Feature: Win A Miracle Piano Teaching System
Project: TV Transmitter For UHF VCRs by John Clarke
Project: Build An Infrared Light Beam Relay by Darren Yates
Vintage Radio: Power supplies for battery receivers by John Hill
Back Issues
Serviceman's Log: When the ghost comes early by The TV Serviceman
Feature: Remote Control by Bob Young
Project: Compact Solid-State Laser Pointer by Leo Simpson
Feature: Computer Bits by Jennifer Bonnitcha
Project: Build A Colour TV Pattern Generator, Pt.2 by John Clarke
Feature: The Story Of Electrical Energy; Pt.16 by Bryan Maher
Order Form
Feature: Index to Volume 4
Market Centre
Advertising Index
Outer Back Cover

This is only a preview of the December 1991 issue of Silicon Chip.

You can view 49 of the 96 pages in the full issue, including the advertisments.

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- AUSTRALIA'S DYNAMIC ~ ELECTRONICS MAGAZINE~ SERVICING - VINTAGE RADIO - COMPUTERS - AMATEUR RADIO - PROJECTS TO BUILD TV Transmitter For UHF VCRs Solid-State Laser Pointer FLUKE AND PHILIPS - THE GLOBAL ALLIANCE IN TEST & MEASUREMENT e FLUKE .. PHILIPS Introducing ScopeMeter TM There's More Than One Reason to Reach for It In fact there's every reason to reach for ScopeMeter. Because only ScopeMeter combines the expertise of Fluke and Philips to bring you a dual-channel digital scope along with everything you've come to expect from Fluke digital multimeters. The result, an integrated scope-and-multimeter that lets you see a waveform and digital meter display at the same time from the same input. Or switch between high-precision Scope and Meter functions with the touch of a key. That makes it faster and easier than ever to capture, store and analyze precisely what you're looking for. At aprice that looks good, too. To get your hands on a ScopeMeter, contact your Philips sales office or your nearest authorized Philips/Fluke distributor. Built to Take It ■ ScopeMeter Now there's only one to reach for Double Duty ■ Simply Easy Integrated 50 MHz digital storage scope and 3000-count (3- 2/3 digit) muhimeter. ■ Precision Min/Max Record and 40 ns Glitch Capture make it easy to troubleshoot intermittent failures. ■ Simultaneous waveform and digital display on a backlit screen you can read across the room. ■ Completely sealed against water, dust and contaminants. ■ EM/ protected and measures up to 600 volts rms. ■ Rugged construction with shock-resistant holster. ■ Three-year warranty. ■ ■ ■ Intuitive front panel layout for simple, straightforward operation. Pop-up menus and five function keys for easy control. Autoset key automatically sets voltage, time and trigger functions. Goes Wherever You Go Runs on rechargeable NiCad Batteries, standard C-cells or the included line vohage adapterIbattery charger. ■ Adjustable tilt-stand comes in handy as a hanger, too. ■ Compatible with a wide range of multimeter and scope accessories. Be No. 1with Fluke and Philips For further information please contact your local Philips Test & Measurement Organisation: SYDNEY /02/ 888 0416 MELBOURNE /03/ 881 3666 PEHTH /09/ 277 4199 WELUNGTON /04/ 88 9788 PHILIPS BRISBANE /07) 844 0191 ADELAIDE /08/ 348 2888 AUCKLAND /09) 89 4160 II Our factory is ISO-9OO I certified VOLUME4 NUMBER12 - . December 1991 FEATURES THIS TV TRANSMITTER enables you to transmit signals from the UHF output of your VCR to a second TV set in the house without messy splitters and cables. Details page 14. (Warning: suitable for VCRs with a UHF modulator only). 6 The Miracle Piano Teaching System by Darren Yates Your computer teaches you how to play 13 Win A Miracle Piano Teaching System Just fill in the coupon & send it to SILICON CHIP 76 The Story Of Electrical Energy, Pt.16 by Bryan Maher Pressurised fluidised bed combustion PROJECTS TO BUILD • ·14 TV Transmitter For UHF VCRs by John Clarke Transmits to a second TV set without messy cables ALARM TRIGGl:A~D 26 Build An lnfrared Light Beam Relay by Darren Yates Use it to monitor a doorway or a path LIGHT BEAM RELAY 60 Compact Solid-State Laser Pointer by Leo Simpson Easy to build, runs off three AA-size cells 68 Build A Colour TV Pattern Generator, Pt.2 by John Clarke Final article has the construction details SPECIAL COLUMNS WHEN YOU WALK through the invisible infrared beam generated by this project, it triggers an alarm for a ,1-second period. Find out how to build it by turning to page 26. 32 Vintage Radio by John Hill Power supplies for battery receivers 40 Serviceman's Log by the TV Serviceman When the ghost comes early 53 Remote Control by Bob Young Motors for electric flight models 64 Computer Bits by Jennifer Bonnitcha Windows 3 & the dreaded Unrecoverable Application Error DEPARTMENTS 4 Publisher's Letter 5 Mailbag 36 Back Issues 56 Circuit Notebook 66 Computer Update 81 Bookshelf 84 Product Showcase 88 Ask Silicon Chip 91 Subscription Page 92 Index To Volume 4 94 Market Centre 96 Advertising Index ~ ✓ OK, SO THE DAMAGE wasn't as bad as this but the Serviceman did come close to a major "oops" this month. He also delved into the spiritual world & found that electronic equipment definitely doesn't go better with Coca Cola®. DECEMBER1991 1 Me,~y Christmas F rom. CITIZEN LCD Colour TV & Video Monitor CITIZEN ED7800 Digital Pocket Diary ■ ■ ■ 2.2" Screen Automatic tuning system ■ A/V Inp u t Jack ■ Palm 32K Memory, Telephone Directory, Memo Reminder, Schedule Organizer, Calender, Home Time, Dally Alarm, World Time, Calculator, and More ! t size only $195.00 iii Now $199.00 AVS-30 Video Transmitter Portable P.A./Gultar Amp ■ O utput: ex tension cables around the house. ■ O u tput Channel: UHF30 ■ l0mtr. Range ,iii. ■ Power Supply lncl. 10 watts ■ 12V DC/240V AC Operation ■ Volume, Bass, Treble Controls ■ 6.5" Speaker ■ M lc. Input ■ Guitar Input ■ 240x285x155mm only $89.95 only $149.00 t PORTASOl PRO IRON KIT Butane Gas Power' d Ktt Includes: ■ Soldering Tip ■ Blow Torch ■ Ho t Blower ■ Hot Knile ■ FREE GAS I!! only $69.95 Hand-Held POCKET TRANSLATOR ■ Instant word conversion of ENGLISH, FRENCH, GERMAN, SPANISH, ITALIAN. ■ l,400 words In each language. IJ Home/Of/Jee SECURITY ALARM SYSTEM KIT KJt Contains: lx Alarm Panel ■ lx P(R Detector lx Power Supply ■ lx Horn Speaker 3x Reed Switches ■ lx Back-up Battery ■ ■ ■ only $349.00 AVM-3 ■ (;::I Audio/Video Mixer Ideal for the Video Camera Buff, who wish to dubb thler own narration and back-ground music to existing video tape recordings. Now $39.95 only $169.00 APS305 Adjustable Bench Regulated Power Supply A-3000 Remote Control Unit ■ ■ 0-30 volt DC " 0-5 amps Reverse polarity protection ■ Current llmltlng ■ Dual meters ■ Fully bu ilt only $199.00 ■ ■ ■ ■ ■ ■ N.O./N.C. relay output up to 5 amps 12 voJt DC operoted Complete with two remote keys ■ 10 meter range ■ Control Just about anything I ■ TX-60 TX-90 VX-60 VX-90 MRX-60 MRX-90 Normal Normal Chrome Chrome Metal Metal $2.45ea. $2.95ea. $3.S0ea. $3.95ea. $6.99ea. $7.99ea. VOTED BEST TAPE What HiFi ? AWARDS $22.00/10 $26.00/10 $32.00/10 $36 .00/10 $62.00/10 $72.00/10 ill ~ ■ AM , FM, SW, TV , Air, Marine and Morel Now $99.95 save $50.00 Remote Access Answering Machine HSA4330 3 way 30 watt Chassis Punch Set S ize: 16, 18, 20 , 30mm ■ Reamer: 3 to 12mm ■ Made In Japan Now $49.95 Remote Message Access ■ Call Screening ■ VOX Controlled ■ Message Indicator ■ 12 months warranty Now $149.00 only $89.00 save $150. 00 41 pee. Driver/Bit Set ■ lpc. T-Bar driver handle ■ 3pcs. illips Bits Bits 4pcs. Ph Slotted . • .)l· •. · ■ ■ 4pcs. Allen Bits _. · ·, i .. · :<: ■ 2pcs. Square Bits .-~ 6pcs. Torx Bits " ■ 9pcs. Metric sockets ~ · ■ 9pcs. SAE sockets . ■ . : i~~: t{t4:ia~ct~~t adaptor FLUKE 79 SERIES II ■ ■ ■ ■ Capacitance Frequency Analog bar graph 4,000 count display ■ Touch Hold ■ 0.3% basic acc . ■ Continuity beeper ■ 3 year warranty I $359.00 Capacity: 2kg/4.5 pounds ■ Digital Read-out ■ Gram or ou nce reading ■ Battery operated ■ PLUS MORE 111 . ,... only $19.95 ■ lpc. 90deg. adaptor ■ only $59.95 AM/FM PLL TUNER ■ LED Frequency readout ■ FET FM front end ■ 20 station memory ■ A uto search tuning Now only $199.00 Butane Pencil Torch PHONE/FAX SWITCH ■ Eliminates dedicated Fax lines ■ Fully automatic ■ Connecting leads supplied ■ Slim-Line design Rl2 months warranty ■ The "Butane Pencil Torch" wHJ melt solder, sliver solder, small brazing rod, glass tubing , and many other materials, only $9. 95 ■ Freq. up to 20MHz Sen. Sm V /DIV to I0V /DIV Sweep: 0.Sus/DIV to S0ms/DIV ■ Includes 2 K 1:1 10:l probes ■ 12 months warranty ■ 4" Screen ■ Dimensions : 212 K 133 x 336mm ■ Detects Propane, Butane and Methane gases, Inbullt visual and audlable alarm. ■ N.O./N.C. output !or alarm systems. ■ 12 volt DC operation . ■ ■ ■ Now $59.95 only $495.00 ■ 3x ■ Ix milling cu t ters wire brus h ■ Ix grinding wheel ■ 4K drill bits ■ 5x ch uck colle t s ■ 6x eraser sticks ■ 10,000 RPM Drill ■ Handy carry case $62.50 A. C.N. 001-372-372 I JIC-678N (LPG,LNG) Gas Leakage Detector CI-118A 20MHz 2 Channel Oscilloscope SuperTool FUJI "AA" NICad ■ ■ 1.2 volt c, S00mAH Made In Japan save $40.00 240 volt AC Mains Surge Protector ■ Protect your computer, HlFl etc. t.19aJnst voltage surges. ■ Designed to substantlatly reduce the posslbJllty of damage to your equipment. ,~ Now only $2.95 each - Weather Proof Speakers ■ 30 watts RMS. 84dB/Wm •· ■ 70Hz to 20KHz ■ 116xl20xl86mm ■ Mounting Brackets Included ,.··· ■ ,;;t5 . . . ■ ARLEc ■ ■ AVAILABLE MID JANUARY 1992 "High Performance " save $100.00 Ideal for watching a video In the kitchen, bedroom, etc. without having to move your complete VCR system or having long RY-610 PRO SERIES Multlband Receiver That's Audio Tapes only $22.95 /.:il- ] I ,. ·- : f ~l . / ~<_) <I. E LE C T R ON IC -...-..:1E1.I.-"1;:i.:.:.1<11E!':I.· PLUS CLOCK ■ ■ 12/24 hour dual timer/clock 2 count-down timers ■ 2 pre-set memories ■ Count-up timer ■ Disp lays Hours, Minutes, Seconds. ■ Built-In alarms only $19.95 David Reid Electronics 19 memory Hands-Free Telephone Computer Diskettes ■ ■ ■ ■ 5.25" 5.25" 3.5" 3.5" D.S.D.D. D.S.H.D. D.S.D.D. D.S.H.D. $4.70/10 $8.70/10 $8.95/10 $21.00/10 ■ Tone/Pulse sw ltchable diallng 16 one-touch memor ies 3 priority memories Last number redial ■ Built-in two way speaker phone ■ 12 months warranty Be quick for this one 11 PS228 ARLEC 6 & 12 V Battery Charger ■ Charges 6 & 12 volt batteries HI and Lo charge rate selector Large ammeter Short circuit proof ■ 2 year warranty ■ ■ ■ A vial/on Head-Set High performance, noise attenuating earphones. ■ Noise canelling microphone ■ Oil filled ear cushions ■ Standard aircraft jacks fitted only $189.00 Cassette Tape Eraser ■ No battery or liquid required ■ Works on Pos/Neg Iron fields ■ Powerful and effective action ■ Simply pass the tape through the eraser a few times to erase tape Now $5.00 Iii Portable CD Mount (9V 216) cleaning keyboards, camera lenses, audio equipment, and more!! ■ Size: 115 x 38 mm (body only) approx. ■ Battery not included Dual temperature range: 400 & 600 C 1600 watts output High Air-flow rate ■ 12 months warranty The PDSl Portable Disc Shuttle with the new NAVCOM suspension system allows you to mount your OlscMan In your car and virtually eliminates skipping or mlstraklng. ■ Complete with swivel base, platform, brackets and all mounting hardware. ■ Made In U.S.A. only · $49.95 and Sensitivity adjustments ■ Lights can be operated manually ■ Maximum 15 metre range ■ Weatherproof housing only $59.95 only $69.95 Car Alarm Warning Light "A Claytons Car Alarm " HAKKO ■ ■ ■ ■ ■ ■ 12 volt operation Starts [lashing when Ignition Is off Stops flashing when Ignition Is on ■ Simple connection ■ ■ only $13.95 Iron flame torch ■ Wide flame torch ~1'1.ACEHE/IT · Limited Stocks! -~ ~,,. ··-· Htiit1f' •~•:r!'~ '!t Now $37.95 Nylon Callpers Great for the tool box Better than a ruler 10 volt AC " 1 amp Suitable for NetCom modems requiring a 9 volt AC supply ■ Also used for a host o( o ther products ~ only $19.95 . "A very RARE product " Temp. AdJ.: 200 - 480 deg. C 24 volt <at> 50 watt element Large range of tips avaJlable Made In Japan 12 months warranty IBM Printer Cables DB-25 male to 36 centronlcs male ■ ■ ■ ■ 1.8 meters 3 meters 5 meters 10 meters Check Insulation breakdown ■ 500V 1000V swltchable ■ Sult Electricians/Technicians ■ Complete kit Allows you to connect your CD and another Aux. unit to one audio Input in your amp. ■ RCA Inputs/output ■ Switch up to 4 pairs of stereo speake rs ■ Each speaker set can be Individually selected. four can be switched on at the same time. ■ All J..2V DC to 240V AC Inverter only $69.95 only $199.00 Watchman PRO Torch Heavy Duty Aircraft aluminium Brilliant Krypton globe Adjustable focus Uses 4 x D cells (not Included) only $35.95 ■ ■ ■ 10.5-16 volt DC operation N.C. contact switch N.C. tamper switch ■ 84 deg. " 12M range ■ Walk test Indicator a • FMA-10 Amplified Indoor UHF/VHF/FM Antenna ■ 15dB amplifier (built-In) ■ 75 ohm coax and plug ■ 40 -890 MHz ■ 240V AC supply Overvoltage, Fused Input and ou tpu t. ■ Low battery Indicator-Audio buzzer ■ 50x135x74mm ■ fnput via clg. lighter plug - ■ Output via 3 pin Aust. socket ■ LED Indicators monitor JN/OUT volts. a, only $79.00' only $23.95 ■ Cont.power: 140Watts, 200W peak ■ Protection: Overload, Undervoltage, ■ ■ ■ ■ HDS90L Digital Probe type Multimeter : }~t~~!ta~~~ ranging ■ Vo lts AC/DC, Amps AC/DC, Logic, Ohms, Diode test, Buzzer. Hold ■ Data Now $54.95 Now $59.95 David Reid 127 York St. SYDNEY 2000 Electronics P.O. Box Q103, SYDNEY 2000 Post ond Packing PH: (02) 267 1385 FAX: (02) 2618905 ~ SAME DAY MAILORDER DESPATCH* ~ Din=Club ~ lnternallonof ~ . · - ' · .,,,, A.C.N. 001-372-372 $9.90 $19.95 $36.95 $69.95 SSS4 Four Way Speaker Switch m y - p < > w ~ r 2C>C> MEGOHM Meter Kit ■ 926/50 CDA-4 CD Adaptor Switching Unit only $23.95 ■ ■ ·. Soldering Station was $19.95 10 volt AC Plug Pack • Be quick for this one 11 ■ Now $9.95 -7 . only _ $199.00 ■ Flameless gas soldering ■ High temperature pencil ■ Ho t knife ■ Hot blower ■ 150mm ■ ■ ■ Timing Vulcan 30 Soldering Kit ■ Mini-Vacuum Cleaner ■ Battery operated ■ Just the thing for ■ ■ Night Watch PIR Flood light Controller ■ 12 months w a r r a n t ~ only $89.95 ■ only $44.00 Heat-Shrinlr Gun ■ ■ ■ ■ : i~~esc:'n:r~Ptroved ARLEc s· $5 - $25 ........ $4.00 $26 - $50 ...... $6.00 $51 - $100 ...... $7.00 f101 - $499 .... $9.00 $500 + , •• ,., •• , ••• FREE Ea , I +.-,, •~g ,? 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 Sales & Marketing Mgr. Angela Clarke, B.A.(Comm.) Phone (02) 979 5644 Mobile phone (018) 28 5532 Regular Contributors Brendan Akhurst Jennifer Bonnitcha, B.A. Garry Cratt, VK2YBX Marque Crozman John Hill Jim Lawler, MTETIA Bryan Maher, M.E., B.Sc. Jim Yalden, VK2YGY Bob Young Photography Stuart Bryce Editorial Advisory Panel Philip Watson, MIREE, VK2ZPW Norman Marks Steve Payor, B.Sc., B.E . SILICON CHIP is published 12 times a year by Silicon Chip Publications Pty Ltd. A.C.N. 003 205 490. All material copyright©. No part of this publication may be reproduced without the written consent of the publisher. Printing: Magazine Printers Ply Ltd, Alexandria, NSW; Macquarie Print, Dubbo, NSW. Distribution: Network Distribution Company. Subscription rates: $42 per year in Australia. For overseas rates, see the subscription page in this issue. Liability: Devices or circuits described in SILICON CHIP may be covered by patents. SILICON CHIP disclaims any liability for the infringement of such patents by the manufacturing or selling of any such equipment. Editorial & advertising offices: Unit 1a/77-79 Bassett Street, Mona Vale, NSW 2103. Postal address: PO Box 139, Collaroy Beach, NSW 2097. Phone (02) 979 5644. Fax (02) 979 6503. ISSN 1030-2662 4 SILICON CHIP Music and computers - a new way to learn At some time in our lives, most of us have a yearning to make music. It is a wonderful way of self-expression that is quite different from most other pastimes. Sadly though, relatively few people have had the chance to learn music and of those who have, many have found the process of learning music too rigorous to suit their temperament and lifestyle. Up till now, most of these people would have resigned themselves to that fact and have settled for the enjoyment of listening to music - a pastime that is highly satisfying in itself. But now there is a new development in the music teaching scene and that is the Miracle keyboard reviewed in this issue. When you first see this instrument it looks little different from the many other relatively cheap keyboards on the market. The difference with this Miracle unit is that it links to your computer and comes with software discs that enable you to teach yourself to play. Some of you might be cynical about the concept but we think it has a number of advantages over conventional methods of teaching. First, the computer is infinitely patient and not in the least censorious if you are having difficulty with a particular lesson. So there is no need to feel embarrassed. Second, you can take a lesson at the keyboard at any time, something that is just not possible with a human teacher. Third, you don't have to pay the not inconsiderable charges of music teachers, a fact which can be taken into ,consideration if you decide to purchase the instrument. Naturally, the Miracle won't suit everyone but it is certainly an interesting teaching concept which could perhaps be taken further in the future. Might we see a guitar/computer learning system or one involving wind instruments? And might the concept be extended to other areas such as a computer fitness system? The computer could perhaps be connected to an exercise machine and might gradually bring you up to a good level of fitness in the privacy of your own home. Which ever way you look at it, the future is-indeed bright for computers and we are well on the way to the day when they will be a fixture in every home. And incidentally, if you haven't already realised it, computers are currently exceptionally good value so if you are thinking of buying, now is the time. As 1991 draws to a close, I and the staff of SILICON CHIP thank you for your continuing support and wish you a happy and safe Christmas. Leo Simpson MAILBAG The pursuit of audio excellence Over the last 20 years, one of my passions has been the pursuit of excellence in electrostatic speaker design and construction, and to design audio projects. It is because of this that I have decided to take the step of putting some of my observations and views in print to stimulate discussion and feedback. Over the last 2 years, I have taken particular interest in slew rate induced distortion (SID).' My design philosophy has always been to keep things simple and totally symmetrical, and it may well be that the fantastic results obtained from audio equipment has been more by accident than good design. An American engineer, Walt Jung, has had a great deal of influence on my ideas since the publication of his extensive research papers on SID in "The Audio Amateur" magazine. While I do not agree with all of his conclusions, the basic concepts of ensuring that all devices in the audio chain have acceptable slew rates and that the loads are correctly (and symmetrically) driven are most important. After testing some sonically badsounding amplifiers, I was astonished to find out that most had either asymmetrical current sourcing and sinking capability or terrible slew rates at frequencies as low as 1kHz. While a 100W RMS amplifier requires a slew rate capability of about 60V/µs, some measured as low as 3V/µs. Some valve amplifiers also tested just as bad while some measured as high as 100V/µs. Preamplifiers proved just as bad under test, with the best being allvalve, FET or bipolar designs, the worst those using 1st or 2nd generation op amps. A couple of designs using current technology high performance op amps tested fine but still sonically inferior. My opinion is that the downfall of op amp designs is because all op amps use class "B" output stages not class ''A" and usually have fabricated symmetrical output stages because it is too costly to use complementary devices. If you agree with this, just think about all of those op amps used in the audio output stages of your CD player (no wonder valve CD players are becoming popular), and the mixing desks, digital recorders and audio processors used in the recording process. Some of the best sounding recordings I have in my possession were recorded with an analog Ampex stereo reel-to-reel broadcast recorder, using Neuman or AKG valve microphones and EMI valve mixers. By the way, I have no bias against digital recorders but against the design of the analog chains used before the ADCs and after the DACs. I am also particularly interested in absolute or reference speaker phase. Unknown to most is the fact that live music when played or recorded is not symmetrical on positive and negative going half cycles (just look at the waveform on a scope). This can cause additional problems with AC-coupled amplifiers due to DC drift but the main point is that most audio sources and amplifiers frequently reverse the absolute phase of the recorded signal. Finally, I would appreciate it if you would publish my name and address for those interested in forming an Australian Speaker Builders Club. Graham Dicker, PO Box 183, Blackwood SA 5051. Phone (08) 322 4229. Loop system for partially deaf Could you please publish an article in your magazine dealing with "loop systems" for partially deaf people who use a hearing aid. My father, who is suffering from "industrial deafness", could really benefit from one of these systems. I would like to construct two of these systems, one for the lounge room and one for his bedroom. I would like to connect these units to televisions in both rooms. The TV in the lounge room is connected to the hifi system which sounds great but it still isn't clear enough for my father to understand what is being said. My knowledge of"loop systems" SILICON CHIP, PO Box 139, Collaroy Beach 2097. is limited - all I know is that they work by magnetic induction and audio is fed into a loop of wire around the room. I would like to know what sort of audio power and impedance is required to run such a system. Thanks very much for your project on the DC-to-DC power converter described in the January 1991 issue of SILICON CHIP. I have been experimenting with the circuitry using higher powered Mosfets, a larger output transformer and power transistors (BD139s) to drive the gates of the Mosfet output devices. The modified version can produce an output of approximately 300 watts continuous power until the car battery or alternator goes into self-destruct mode! The system at the moment is set up in the back of a Commodore Station Wagon, using two large bass reflex speaker boxes, each containing a 12inch Etone woofer with whizzer cone, and a pair of Motorola piezo tweeters with crossover network. The sound source is a Sony disc player with radio. "So loud but yet so clear" was a comment from one of the local car hifi retailers in town - not bad for a homemade car audio amplifier. After having listened to commercially available "top of the line" sound systems in the demo cars (costing many thousands of dollars), the homemade system, in my opinion, sounds as good, if not better. Please keep up the good work. P. Kutas, Shortland, NSW. People in glass houses shouldn't ... Your reference .to a meter movement of 100mA FSD on page 91 of the October issue was rather naughty after your tough review of the Radio Theory Handbook for Amateurs on page 53 of the same issue. Bill Pascoe, Cooma,NSW. Comment: It was pounds to peanuts that such an error would occur in that issue. The text on page 91 should have referred to a meter of 100uA FSD not 100mA. SC DECEMBER1991 5 THE I PIANO TEACHING SYSTEM Learn to play the piano from a computer? Well, that's exactly what you can do with this . amaz1ngnew package. It combines a 4-octave stereo keyboard with your PC, Amiga or Nintendo to produce a system which could revolutionise the way music is taught. By DARREN YATES O YOU REMEMBER as a 10 year-old being trundled off to piano lessons for an hour every Wednesday afternoon? Invariably, you had to miss out on the after-school fun to learn "Good King Wenceslas" and to practice scales, and you wished you were somewhere else. Or maybe you're from the other side of the coin as I was, telling your mum you don 't want to learn the piano and then later regretting it. This may be a bit of an exaggeration but whatever the case, the new Mira- D 6 SrucoN CHIP cle piano teaching system is an exciting and affordable way to get into the world of music in the privacy of your own home computer. The Miracle was developed and designed in the USA and is imported into Australia by Mindscape International. It is currently available for the IBM PC and PC compatibles from all Dick Smith Electronics stores throughout Australia. When we first laid eyes on our review sample for the PC, we mistakenly thought it was just another key- board but a quick look over the packaging showed it was much more. It even included a glowing recommendation from the famed Julliard School of Music in the US. Inside the package In addition to the 4-octave keyboard, the package includes a 12VAC plugpack, a sustain foot pedal, an RS232 cable with a DB9 computer plug, a pair of headphones, software on 5.25inch and 3.5-inch discs, and the user manuals. The computer requirements for the PC version are MS-DOS version 3.1 or later and at least 512Kb of RAM if you are using a CGA monitor, or 640Kb RAM if you have EGA or VGA graphics. The software comes on two 1.2Mb 5.25-inch floppy discs and three 3.5inch 720Kb discs to suit either format. At least one serial port is recommended but we found that you really need two, to use the Miracle to its full potential; one for the keyboard interface and one for a mouse. Itching to see what it could do, we immediately grabbed the discs and started loading them into our workshop 286. Installation To get the most out of the Miracle, the software is best installed onto your hard disc. It occupies about 2Mb or so of space but this dramatically speeds up the operation and saves you swapping discs. After connecting up the Miracle keyboard to the computer, all you need to do is load in disc 1 and type INSTALL. The installation program then automatically loads the program into a directory called MIRACLE. During this process, it tells you when to change discs and confirms the type of system set-up you have. Running the Miracle When the tedious bits have been done, you're prompted to go to the MIRACLE directory on your hard disc and type MIRACLE. A couple of seconds later we were enveloped in music, with the keyboard playing a classical orchestration to some very high quality VGA graphics. In fact, the graphics were very impressive all the way through the program, particularly in VGA format. After going through the initial personalisation screens, you come to the main menu which contains six options: Classroom, Arcade, Studio, Administration, Performance Hall and Practise Room. Classroom This option allows you to go through the 40 lessons that are available on the initial discs. Further discs will be available in the future to extend the number of lessons to 250. The Miracle initially shows you to Lesson 1, but if you're adventurous, This is the Classroom chapter menu. You can select any of the 40 chapters at any time and, at the end of each chapter, you will know how to play another piece of music. You can use either the tab key or the mouse to select an option. you can go through and select any of the "chapters" you wish from 1-40. It also keeps track of which lesson you were going through the last time and allows you to pick up where you left off. During the lessons, the Miracle screen display is very much like a blackboard. It teaches you where the keys are by way of a keyboard shown on the screen, with the keys you are to press highlighted. One of its clever little tricks is that whenever you press a key, the corresponding key is depressed on the keyboard shown on the screen. Even in the first lesson, you get some hands-on practice by learning to play Beethoven's "Ode to Joy". The Miracle first of all demonstrates how it is played by showing both the sheet music and the keyboard, as well as each individual note as it is being played. After you've had a go, the Miracle then tells you how well you played, keeping track of your tempo, the number of wrong keys pressed and even how you pressed the keys . For example, if you don't hold a key down for long enough, the Miracle tells you. In fact, the Miracle checks each mistake you make against 200 error types which it splits into 41 main categories, including notes played too fast and those that have been held for too long. It also decides whether you played it well enough to progress to the next lesson by keeping score in these main categories but you can always bypass it by using the self-select method! Arcade This section is perfect for kids (both big and little) and uses arcade-style games to teach you which notes on the keyboard correspond to those on a piece of sheet music. There are three games: Ducks, Ripchord and Aliens. Ducks is very much like the game you would see at an amusement park. The idea is that ducks swim across lines representing a staff (the five lines on which notes are placed) and when you press the right key on the Miracle keyboard, the duck blows up! Ripchord is a similar style game where you have a certain time limit to play a set of notes or a chord. If you play them in time, the parachutes open for the little men, otherwise they hit the ground head first. Aliens lets you practise note sequences and is a minor variation to the above games. Also included in the arcade section is a Jukebox, which allows you to select and listen to any one of the 100 practice pieces of music (with full backing). Some of these include the themes fromM* A *S*H, Star Wars and a number of Beatles songs. The Studio This is one of the more interesting DECEMBER 1991 7 the whole thing used only just over 5Kb of disc space. Not bad, huh? The only negative thing is that there are no instructions that appear on screen when you first run the Studio. This means that you have to refer to the user manual to start off with but we found that one picks up the rules fairly quickly anyway. Administration This takes care of adding and deleting users, changing the system setup parameters, and checking the progress of a student via the number of lessons started and completed. You can even print out certificates when you have finished a particular section of the Miracle course. You also use this section to exit the program and return to DOS. Performance Hall One of the interesting ways oflearning is through the arcade games. Here, you have to press the correct keys on the Miracle keyboard in order to open the parachutes before the men hit the ground. sections of the program. The Studio turns your computer into an 8-track tape recorder, allowing you to record your own compositions. You simply record one track at a time; eg, bass, then lead, then accompanying background, etc. Each time you record a new track, the Miracle replays the other tracks you have recorded so that you can listen to your composition take shape. What's more, you can feed the stereo output from the keyboard into your hifi gear using the two RCA sockets at the back of the unit. As might be ex- pected, we had quite a bit of fun with this section! The Miracle gives you a choice of 128 different voices, from pianos to guitars to rap drum beats which are selectable from the software. As well, you can change the tempo and the volume of the keyboard by using the tab and arrow keys. You can also store your composition on disc and load it back again later. It uses surprisingly little memory. As an example, we made up a small piece of music using four tracks that ran for about three minutes and A view of one of the lesson "blackboard" screens. Each screen discusses a new topic. The keyboard display at the bottom of the screen is interactive with the Miracle keyboard, showing the keys you have pressed. 8 SILICON CHIP At the end of each lesson, you have learnt to play a new piece of music. The Miracle then takes you to the Performance Hall to play it with an accompanying orchestra, to test out how well you know it (rats!). On the screen is the sheet music of the piece you are about to play, with a small arrow indicating which note you should be up to, as well as the keyboard to show you which note you should be playing. This may sound a little intimidating but you can slow the tempo right down to a crawl if you're not confident. A metronome plays in the background to advise you of the tempo. You can even decide to play with only one hand if you want to. When you come to playing a piece, both the manuscript of the music and the keyboard are displayed. Small arrows indicate which note you should be playing at any one time both on the keyboard and on the sheet music. Electronics Workbench® This screen view shows the Miracle's Studio option. You have an 8-track recorder at your disposal to record, store and playback your musical masterpiece. You can select the instruments as well as the tempo and volume via the mouse or keyboard·: The block in the centre simulates an 8-channel LED bargraph display. The Practise Room The practise room is where you go to practise the pieces you have learnt during the lessons, but you can also choose your own piece out of the 100 available. There are five options here. You can try your hand at playing solo, or you can play a duet with the Miracle or listen to the Miracle play a piece in its own in demo mode. You can also practise playing notes at your own · pace or just practise getting the right rhythm and playing any note. The keyboard The keyboard itself looks rather plain on the outside but considering it has 128-tone stereo sound, velocitysensitive keys, digitally controlled volume and a MIDI interface , it still beats many currently available keyboards. And if you ever get sick of going through the software, you can switch off the computer, pull out the RS232 cable and use the keyboard on its own. The only problem you have is that there is no specific way of telling which tone you have selected, other than counting through the voices one by one and looking up the selei;;tion table. But many of the voices, particularly some of the vibraphones, are very sweet indeed. The system also comes with two well-written manuals that don't require you to be a computer programmer to figure out what to do. All instructions are followed through step-by-step with ·s mall graphics of the video screens as you come to them. The software can be run using either a mouse or the keyboard and is very easy to drive. Overall, the Miracle piano teaching system is a winner. It's the perfect way to start yourself or your children on the road to learning music. It not only allows you to learn how to play in the privacy of your own home but also includes many features to keep children of all ages interested enough to persist and not give up too early. The Miracle piano teaching system is available from all Dick Smith Electronics stores and, at $699, it's a great investment in either your own or your children's musical education. We loved it! SC ~ _, ., . . . .-- _ I, I: _lJ.E__;~~.~~i~~~:~ ,.~ ...~..~..u""l, ,_,_. -· - ' = .;. "':-d:-.. 1 "'·,. C .. :~ .. , : : --•1.. '• ) K~ U .. N A i_j Q 0 <at> , ..... ~ ~~~~~ == 00000 000 MU I Build and simulate both analog and digital circuits, complete with simulated instruments on your computer! FEATURES • Quick and simple circuit entry • Digital and Analog Modules included, complete with all components • Simulated instruments: dual trace scope, spectrum analyser, function generator, multimeter, digital word generator and logic analyser • Complete control over all component values and parameters • Print: circuit schematics, parts list, instrument readings, macros • Logic conversion -truth table to Boolean formula to logic gates • Customisable hypertext help system THREE VERSIONS • Professional Version: EGNVGA colour display; unli mited components • Personal Plus Version: Monochrome display; unlimited components • Personal Version: Monochrome display; limited to 20 components per circuit ----------------I YES ■ I want ELECTRONICS WORKBENCH in my computer Professional Version Personal Plus Version Personal Version $429 $229 $149 Plus $7 Delivery Enclosed is my cheque/money order for $_ _ ___ or Please debit my Ca rd No.J O Bankcard O Mastercard IIIIIIIIIIIIIIII Signature _ _ _ _ __ _ _ Expiry Date _ _/_ _ Name _ _ _ _ _ __ _ _ _ _ _ __ _ __ _ Street _ _ _ _ __ _ _ __ _ _ _ _ __ __ Suburb/Town - - - - -- - - Postcode - -- Send to: Emona Instruments, PO Box 15, Camperdown, NSW 2050. ·-----------------~ Tel: (02) 519 3933 Fax: (02) 550 1378 DECEMBER1991 9 Refine Your Reception QQ ANTENNA TUNER AND RF PREAMP Improve -the performance of your old shortwave receiver with this easy to build unit. Combining an antenna tuner with an RF preamp and preselector, it's ideal for improving both sensitivity and selectivity. The unit is powered by an external 12V DC source (plug pack not included). Includes all components, hardware, pre-punched silk • screen front panel and prepunched rear panel. CatK-6100 $109 TV COLOUR PATTERN GENERATOR Tune your TV to perform like new again! Generates seven separate patterns for adjusting your picture and tracking down faulty circuitry. It's easy to build and only requires a small amount of wiring. Ideal for video enthusiasts, TV servicemen, hobbyist etc. Comes with all components, hardware, case and pre-punched silk ',. _ screen front panel. Includes · , •... plug-pack . QQ i ! t\ ~ :iJ!;J 'J!..',~ ff,j)/!~ i <at>NOV'91 The Safe Solution QQ NOV/DE C '91 '$119 \ CatK-7355 So real.. .it's alarming! Q MAGNETIC FIELD STRENGTH METER FLASHING DETERRENT LIGHT Minimise the health risk of magnetic radiation with this handy meter. This accurate meter with LCD readout lets you measure the level of magnetic radiation emitted from appliances in the home & wo rk-place. By changing your room layout, you can then minimise your exposure. Comes with deluxe case, all components, hardware and pre-punched silk screen front panel. Requires a 9V battery. $8 995 Cat K-7600 !l~~i]l~i~~i~il I'.: '.~\'"_·•.·_•·.·._:'· _ :~_ Car thieves think twice when they see ..------------t 11 1:_~_ _:,_f!_:_ OCT '91 'ifc:il.!15.!-~iiii i~ f!I,j,'JJ - BUDGET KARAOKE Sing like a star! It's easy-to-build and doesn't require special Karaoke tapes or CD's. By using the principles employed by recording studios, it allows you to replace the vocals on almost any of your favourite tapes or CD's with your own. Includes 'gain' and 'null' controls for sensitivity and signal balance. Come!> in full form with all components, hardware and pre-punched silk screen front panel. Cat K-5300 NOV'91 $3995 Coming Soon! QQ MULTIMETER A low cost multimeter packed with features! It's compact, reliable and great fun to build. With continuity testing, a wide 10A 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 Cat K-4200 ~ ,j)jj - NOV '91 Added Insulation for Extra Safety! Q ~ A Star is Born! Q -<at> temperatures of a car dashboard. Includes all components, PCB, mounting hardware, deluxe bezel case and globe. ~ J . ! J ~ FAN SPEED CONTROLLER Warmer weather is.fast approaching so, while dusting off the old fan, you might like to make it more effective by building this Fan Speed Controller. It's an easy to build full form kit with PCB. Includes components, plastic cas,-,, pre-punched & silk screened front panel, plus mains plug & socket. Complete with a plastic pot for maximum insulation and added safety. Cat K-3086 <at> JULY'91 Please contact your nearest store for availability of the above kits. . $3 295 81229 / MS DSE NICAD BATTERY CHARGERS Charge up to 8 batteries at once. With indicator lights and reverse polarity protection. Both charge AAA, AA, C, D, and 9 volt batteries. Mains operated. NEW SOCKETS AND CONNECTORS 2.1 mm DC Bulkhead Socket 2.5mm DC Bulkhead Socket 2.1mm DC Metal Line Socket 2.5mm DC Metal Line Socket High Density 15 Pin Sub-D Male Plug suits VGA monitors P-1648 P-1650 P-1652 P-1654 $1.95 $1 .95 $2.15 $2.15 Cat P-2710 $3.95 Cat Cat Cat Cat OFC AUDIO CABLES NiCad Charging Cabinet Heavy Duty Charging Cabinet SANGeAN Cat M-9505 Cat M-9506 Extremely high quality oxygen free copper (OFC) cables. Designed for maximum conductivity and minimal resistance. NEW60 x 0.12mm conductors, Figure 8, Spkr. CatW-2013 $0.95/m 315 x 0.12mm conductors: Figure 8, Spkr. Cat W-2017 $3.95/m Super OFC Single Shielded, Audio. Cat W-2032 $1 .95/m Super OFC Figure 8 Twin Shield, Audio. Cat W-2033 $3.95/m 45 MEMORY SHORTWAVE RECEIVER 10 BAND SHORTWAVE RECEIVER There isn't much the Sangean ATS-808 won't do! It has AM/FM plus longwave, mediumwave & shortwave tuning (150kHz to 30MHz). There's a large LCD screen, dial or keypad frequency entry, 45 memories, alarm clock and 3 tuning modes. Includes telescopic antenna, headphone and external antenna sockets. Requires 6 x AA batteries or mains adaptor The Sangean SG-789 receives local AM/FM stations and 8 international shortwave bands. With bandspread tuning and an LED tuning indicator. Includes sockets for headphones and AC adaptor. Requires 3 x AA batteries. Cat D-2834 Cat D-2829 uniden. QUALITY WALKIE TALKIES 70 XLT SCANNER RADIO They're just like the real thing! With easy push-to-talk operation, flexible antenna and a super range. Each requires 1 x 9V battery. No licence required. A quality hand-held scanner. Includes rechargeable NiCad battery pack and AC charger. With 8 Band Coverage plus track tuning and 20 memory channels. It's light, compact and comes with a carry case. Covers 66-88MHz, 136-174 MHz, 406-512MHz. Cat D-1085 Cat D-2740 Music Video Singalong DIGITOR KARAOKE Plugs into your TV or VCR. A superb Karaoke with amplifier and digital voice processor. With microphone and connecting cables. Comes complete with VHS Karaoke tape. Great For Parties PORTABLE KARAOKE Sing along with your favourite tape, etc. It's a two-way speaker system, AM/FM radio, cassette deck, PA amp and mini mixer all in one. Requires 6 x 'C' size batteries or DC adaptor. Cat A-7500 Cat A-7600 Comes with DC adaptor and mic. With VHS Video Tape! KAROKE AUDIO TAPES MAJOR DICK SMITH ELECTRONICS AUTHORISED STOCKISTS: NSW: ARMIDALE: New England Electronics 711655 BALLINA: Ballina Electronics 867022 BATEMAN'S BAY: Baycity Siilht & Souml 725030 BERMAGUI: OlTECH Electronics 934242 BOWRAL: Bowral Electncal Supplies 611000 BROKEN Hill: Hobbies & Electronics 884098 COOTAMUNDRA: Cootamumlra Music & Lile 422561 COffS HARBOUR: Coffs Harbour Electronics 525684 DENILIQUIN: Deni Electronics 813672 DUBBO: Chris's Hi Fi 828711 FORSTER: Forater ~~~i4~~miiIT:~~~~~~r~~r~~~,281~1Et~:GP~n:~a:~~t5&~~~L~~~~::~7on~~~;~ LIGHTNING RIDGE: lightning Ridge Newsagency 290579 LITHGOW: Douroy Photographies 513173 LISMORE: Oecro ElectronicServices214137MOREE: Moree Electronics522091 MUDGEE: Headware 723895 MURWILLUMBAH: Stn~ ~:~:r ~aW~s ~~:1~::J;~'!tPA~ts"1r~~~;i~~~~li~LSON BAY Nelson Ba Elect & ~~ice 834574 RICHMOND: Silicon Crafts 784101 ULLADULLA: Coastal E WA~: Ptiillips ~:~:~~~~i~ ~~k~k~?i~ng~ ~r~~~n~:~~m3J~t~~RAT Jerram Electronics522ti~~fif~b':2/'t 5 1 lH & lM Crawford 5256TT BENALLA: North East Electronics 622710 COLAC: Colac Electronics 312847 MILDURA: Pullman Auto Pro 232882 SHEPPARTON: Andrew Guyatt Electronics 219497 SWAN Hill: Nvah Distnct 1V Service 329303 TRARALGON: Traralgon Electronics 741699 WARRAGUL: Roylaine 234255 WARRNAMBOOL: Koroit St Elec Services 627417 OlD: AYR: Delta Electnx 831566 BOWEN: Delpro Agencies 86 34TT BUNDABERG: Bob Elkin Electronics 521785 tALOUNDRA: Electro-rnart918533 DYSART: Dysart Videotronixs 582107 GLADSTONE: Electronic Enterprises 726660 INGHAM: Masons Electronics 763188 INNISFAIL: lnnisfail Hi.fi 612014 KINGAROY: MD & MM Siegle 624535 MACKAY: Stevens Electronics 511723 MARYBOROUGH: Keller Electronics 214559 MOOLOOLABA Dalma Services 448666 NAMBOUR: Nambour Electronics Shop 411604 PIAL.BA: Keller Electronics 283749 STANTHORPE Granite Belt Communications 813333 TAS: BURNIE: Electronic City 314760 DEVONPORT: Al Electronics 248322 LAUNCESTON: Krrronics 344555 SA: MT GAMBIER: Hutchesson's Communication Ctr 250400 PORT LINCOLN: Basshams 1V & Comp Wo~d 822788 WHYALLA: Eyre Electronics 454764 WA: ALBANY: Micro Electronics 4120TT 1 14 titles to choose from. Sing along with Old Blue Eyes or Old Macdonald. Cat C-8500 ... Cat C-8670 s149s80 TWIN AUDIO TAPES Twin pack Karaoke tapes. Choose from Top 40 hits, rock 'n roll 95 or all time favourites. Cat C- 6010 ... Cat C- 6050 s19 KARAOKE VIDEO TAPES Hits and memories for all tastes. Just follow the words on the screen. _.,T,;lllll'II. S2CJ95 ~::~~~~ril=~~l~~~:~~,i,~=is~ii~~oor/}~tJ't~ Tomek the Elect 732531 81229 / PB COMPUTER-WISE RIGHT NOW YOU'LL FIND THE BIGGEST AND BRIGHTEST COMPUTER PRODUCTS OF 1991, AT LOW PRICES THAfLL SURPRISE YOU! DIGITOR COMPUTERS For affordable power, performance and expandability, one name says it all ... Digitor. DIGITOR 286/16 'AT' DIGITOR 386/20 SX It's fast, built to last and ideal for running Windows applications. The incredible Digitor 386SX is astounding value and it's ideal for business or serious home use! • Fast 16MHz running speed • VGA Colour Monitor • 1Mb RAM (Expandable to 4Mb on board) • 1.2Mb (5.25") Floppy Disk Drive • 40Mb Hard Drive • 2 Serial, 1 Parallel & 1 Games ports • Includes DOS Outstanding Value! $1595 • Fast 20MHz running speed • VGA Colour Monitor • 1 Mb RAM (Expandable to 8Mb on board) • 1.2Mb (5.25") Floppy Disk Drive • 40Mb Hard Drive • 2 Serial, 1 Parallel & 1 Games ports • Includes DOS cat X-8440 An Exceptional Buy! $1895 MIRACLE PIANO TEACHING SYSTEM In Box Of 10 51/4" DS/;:>r, Cat X-3521 $695 31/2" DS/DD Cat X-3508 S995 SOUND BLASTER PRO Introducing the World's First Interactive, Computer Based Piano Teaching System! It simply connects into your Nintendo System, IBM Compatible PC or Amiga System. Now anyone can learn to read and play music. The keyboard is amazing! It features full sized velocity sensitive keys, over 100 instruments and effects! $699 PC Version Cat X-7100 • Stereo Recording, Mixer, DAC and internal speaker • Twin FM chips providing 22 voices • CD-ROM Interface & internal connector for CD Audio • And much, much more! Cat X-2033 Amiga Version (Available On Special Request) ~1: s399 B<;,. -.- . ~TH PHONES SECURITY AUDIO COMPUTERS Nintendo Version Cat X-7105 $599 The new standard in sound cards! With all the sensational Sound Blaster features plus lots more. SUPER VGA CARD More colours and higher resolution! 1024 x768 pixels in 256 colours. 1Mb of memory on board, and drivers for a wide range of software including Microsoft Windows 3. $199 Cat X-2001 DS XPRESS PHONE & MAILORDER SERVICE Outside Sydney (FREE Call) 008 22 6610 Sydney And Enquiries - 888 2105 FAX: (02) 805 1986 or write to OS 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 871 7722 • Brookvale 905 0441 • Bondi 387 1444 • Campbelltown 27 2199 • Chatswood Chase 4111955 • Chullora 842 8922 • Gore Hill 439 5311 • Gosford 25 0235 • Hornsby 477 8633 • Hurstville 580 6822 • Kotara 56 2092 • Liverpool 800 9888 • Maitland 33 7886 • Miranda 525 2722 • Newcastle 611898 • North Ryde 878 3855 • Orange SU 400 • Parramatta 889 2188 • Penrith 32 3400 • Railway Square 211 3777 • Sydney City 287 9111 • Tamworth 681711 • Wollongong 28 3800ACT• Belconnen (08) 253 1785 • Fyshwick 80 4944 VIC • Ballarat 31 5433 • Bendigo 43 0388 • Box Hill 890 0899 • Coburg 383 4455 • Dandenong 794 9377 • East Brighton 592 2388 • Essendon 379 7444 • Footscray 889 2055 • Frankston 783 9144 • Geelong 232 711 • Melbourne City 399 Elizabeth St 328 8088 & 246 Bourke St 639 0396 • Richmond 428 1614 • Ringwood 879 5338 • Springvale 547 0522 QLD • Brisbane City 229 9377 •Buranda 391 6233 • Cairns 311 515 • Chermside 359 6255 • Redbank 288 5599 • Rockhampton 27 9844 • Southport 32 9033 • Toowoomba 38 4300 • Townsville 72 5722 • Underwood 341 0844 •SA• Adelaide City 223 4122 • Beverley 3471900 • Elizabeth 255 6099 • Enfield 280 6088 • St. Marys 277 8977 WA • Cannington 451 8686 • Fremantle 335 9733 • Perth City 481 3281 • Midland 2501460 • Northbridge 328 6944 TAS • Hobart 31 0800 !ff• Stuart Park 811977 STORE ACROSS AUSTRALIA AND NEW ZEALAND YOUR EIGHT SPECIALTY STORES IN ONE DICK SMITH (WHOLESALE) PTY LTD A.C.N. 000 908 716 SPONSORED BY SILICON CHIP & DICK SMITH ELECTRONICS ••••••••••••••••••••••••••••••••••••••• THE MI CLE PIANO TEACHING SYSTEM Designed to work with your IBM PC or PC-compatible computer, Commodore Amiga or Nintendo ~ntertainment System, the Miracle Piano Teaching System makes learning music a pleasure. As reviewed on page 6 of this month's issue, the Miracle is available from all Dick Smith Electronics stores throughout Australia. Open to all readers of SILICON CHIP magazine To enter this draw, all you have to do is fill out the coupon below and send it in to us by December 31st, 1991. The competition is open to all readers of SILICON CHIP. Existing and new subscribers to SILICON CHIP are entitled to two entries. Send your entry in to SILICON CHIP, PO Box 139, Collaroy, NSW 2097. r------------------• • I WIN A MIRACLE I I PIANO TEACHING SYSTEM I I Name I Street I I Suburb/town Postcode I I I I I I I I I I ~------------------~ Rules & Conditions (1) The competition is open only to Australian residents. (2) All existing and new subscribers to SILICON CHIP are entitled to two entries. (3) Entries received after the closing date will not be included. (4) Employees or family members of Silicon Chip Publications Pty Ltd and Dick Smith Electronics Pty Ltd are not eligible to enter. (5) South Australian residents do not have to purchase the magazine to enter but may enter only once by submitting their name, address and a hand-drawn facsim ile of the competition to Silicon Chip Publications Pty Ltd, PO Box 139, Collaroy, NSW 2097. (6) The judges' decision is final and no correspondence will be entered into. (7) The description of the competition and instructions on how to enter form a part of the competition conditions. (8) The competition begins on November 29th, 1991 and closes with the last mail on 31 st December, 1991 . (9) The prize is not transferable or exchangeable and may not be converted to cash. (10) Th.e draw will take place in Sydney on 8th January, 1992 and will be announced in the March 1992 issue of SILICON CHIP magazine. ( 10) The prize is a Miracle Piano Teaching System valued at $699.00. The promoter is Silicon Chip Publications Pty Ltd, Unit 1A, 77 Bassett Street, Mona Vale, NSW 2103. Permit TC TC91/0000 issued under the Lotteries and Art Unions Act, 1901; Raffles Bingo Permit 91/0000; ACT Permit TP91/0000 issued under the Lotteries Act, 1964; NT Permit No 91/0000. DECEMBER 1991 13 TV transmitter for video recorders This TV transmitter enables you to transmit signals from the UHF output of your VCR to a second TV set in the house without messy splitters and cables. It uses two ICs & has a range of about 20 metres. By JOHN CLARKE How many times have you wanted to watch something from your VCR on another TV set located in another room in your house? It is possible to do so, of course, by running a cable from your VCR to the second TV set. Or you can transmit the signal to the set using this simpie transmitter. The first option of running a cable 14 SILICON CHIP . can involve a lot of installation. First, you have to split the signal from the VCR to obtain two outputs, one for the main TV set and the other for the second set. After that, you have to run the cable and, in some cases, this can be very difficult since it may involve drilling through brickwork or crawling around in confined spaces in the ceiling or under the house. Another problem with cable is that it can look unsightly if it is not installed properly. A cable outlet also ties the second set to a particular room, at least as far as receiving VCR signals is concerned. Using the TV Transmitter solves these problems. You do not need to run a cable and the TV set can be moved freely about the house without the need to relocate any wiring. Fig.1 shows the general arrangement of the two schemes. Fig. l(a) shows the conventional splitter and cable method while Fig.l(b) shows the arrangement using the TV Transmitter. The TV Transmitter operates by amplifying the UHF signal from the RF output of a VCR and then coupling it to a small antenna. This antenna then radiates the signal to a second identical antenna at the remote TV set. The antennas are 3-element Yagis which have a nominal gain of about 7dB. Because the transmission is at ultra high frequency (UHF), the antennas are quite small and relatively unobtrusive. Their main advantages when compared to a simple half-wave dipole are that they are quite directional and provide greater range. Note that, strictly speaking, the TV Transmitter is really a high gain amplifier, since it does not contain a modulator stage. Nor does it need one in this application, since it is fed from the modulated output of the VCR. Also, because of antenna size limitations, the device is suitable only for use with VCRs that have a UHF output (see panel). Circuit details Refer now to Fig.2 for the circuit details. As can be seen, the TV Transmitter is a relatively simple device based on two OM350 hybrid wideband amplifier ICs. This IC is a Philips device and has a nominal gain of 18dB over the frequency range from 40-860MHz. Our circuit uses two OM350 ICs in series to provide a gain of 36dB. The RF output from the VCR is coupled to IC1 via a 220pF capacitor. Following amplification in IC1, the signal appears at pin 5 and drives inductive load 11, a Philips wideband choke. The amplified signal is then coupled to a 220pF capacitor and split two ways: (1) to the input of IC2; and (2) to the main TV set via an s2on resistor and another 220pF capacitor. The 820Q resistor provides about 21dB of signal attenuation when connected to a 75Q TV input. This means that the overall signal loss from the VCR to the TV is about 3dB, due to the 18dB of gain in IC1. This 3dB signal loss is not important since the output from the VCR is more than sufficient to drive a TV input. The amplified output from IC2 is coupled via yet another 220pF capacitor to the output socket and from there to the antenna. Inductor 12 is another Philips choke which performs the same function as 11. Power for the circuit is provided by a 12V DC plugpack supply. A 47Q TV ANTENNA SPLITTER MAIN TV SET VCR REMOTE TV SET Fig.l(a): the conventional splitter & cable method for connecting two TV sets to a VCR. This scheme can become unwieldy if the remote TV set is a long way away from the VCR & the main set. TV ANTENNA TV TRANSMITTER TV IN OUT MAIN TV SET VCR REMOTE TV SET Fig.l(b): the alternative scheme using the TV Transmitter. It operates by amplifying the output from the VCR & then coupling the signal to a small Yagi antenna. The broadcast signal is then picked up by an identical antenna at the remote set. limiting resistor and 12V 1W zener diode regulate the supply to +12V, while two .00lµF capacitors decouple the supply at inductors 11 and 12. Transmit switch Sl switches the supply rail to IC2. When this switch is closed, the circuit is in transmit mode but when Sl is open, IC2 is left unpowered and so no signals reach the antenna. IC1, however, is paw- ered continuously so that signals are always available for the main TV set. Construction Because the circuit operates at UHF, special RF construction techniques are required. All the parts, except the switch and power socket, are mounted on a double-sided PC board coded SC02212911 and measuring 30 x - TRANSMIT ON/OFF S1 47!1 12V FROM •----W,._.-+-------+-----' PLUG-PACK - ~ .,. .001! .001! • II II L1 II II L2 II II 1BdB GAIN 1BdB GAIN r 'T 220 ~ S Q (!UTPUT TOANTENNA -21dB 220pFT L1, L2 : PHILIPS 4312·020-3670 CHOKE ( 6) 75ll OUTPUT 'T TO TV INPUT TV TRANSMITTER Fig.2: the circuit uses two OM350 hybrid wideband amplifier ICs in cascade to provide a nominal gain of 36dB. As well as driving IC2, ICl also drives a 21dB attenuator circuit to provide signal feed for the main TV set. DECEMBEH 1991 15 S1 Warning! ~]-\ • I J·~zot JtJt~2rK~ + • • TOP VIEW , - - - - - - - - - - O U T P U T _ _ _ _ _ _ _~ OUTPUT T O ~ ANTENN/\~ 220p~~ .0 0 1 ~ ~1:-· b•~ mti\to 220pF. .001~ • BASE VIEW Fig.3: install the parts on the two sides of the PC board as shown here & don't forget to install the "pin throughs" where indicated. Be careful with the two ICs, as they can easily be damaged if overheated. The two RF chokes, L1 & L2, are supplied ready wound. 97mm. This is housed in a plastic case measuring 130 x 67 x 43mm and fitted with an adhesive label. Begin construction by carefully affixing the label to the case and drilling out the switch mounting holes. The cutout for the switch can be made by first drilling a hole at the position indicated and then carefully filing it to the required shape. This done, use a sharp utility knife to cut away the labelling from the four corner mounting holes of the lid. The next step is to drill the three mounting holes in the side of the case for the 75Q PAL sockets. After mounting, these sockets are soldered directly to the PC board, with their centre pins passing through the board from the base side to the top side (see Fig.3). The socket positions are marked using the PC board as a template. To do this, place the board flat against the side of the case with the base side of the board facing outwards (orient the board as shown in Fig.3 and centre it top and bottom). Check that the socket holes line up with the labelling on the front panel, then carefully mark the holes with a pencil and Only four components are mounted on the top side of the PC board - the two OM350 ICs, ZD1 & the 47Q resistor. 16 SILICON CHIP This project is suitable only for use with VCRs that have a UHF output (ie, VCRs that require you to set your TV set to a UHF channel). It will not work satisfactorily with VCRs that have a VHF output. Check that your VCR is suitable before rushing out to buy parts for this project. Your VCR manual should state whether the modulator outputs at UHF or VHF and this will also normally be indicated on the back of the VCR. Depending on parts availability, we hope to publish a TV transmitter suitable for VCRs with VHF outputs in a later issue. lightly centre-punch them. The socket holes can now be drilled and reamed to size and holes drilled in one end of the case for mounting the DC power socket. This done , mount the 75Q PAL sockets in position with their solder lugs oriented as shown in one of the photographs. The DC power socket and the on/ off switch can also be mounted at this stage. Fig.3 shows the assembly details for the PC board. Note that some of the parts are mounted on the top side of the board while the remainder are mounted on the base side. There are also several "pin through" points , where a short piece of tinned copper wire is passed through the hole and soldered to both sides of the board. Here's how the parts are installed on the base side of the PC board. Keep all component leads as short as possible. PARTS LIST 1 double-sided PC board, code SC02212911, 30 x 97mm 1 plastic case, 130 x 67 x 43mm 1 Dynamark front panel label, 125 x 64mm 1 12V DC 300mA plug pack 1 2.1 mm DC panel socket 1 2.1 mm DC line plug 3 panel-mount 750 PAL sockets 1 DPDT slider switch 2 Philips 4312 020 3670 chokes 2 Philips OM350 wideband amplifier ICs (IC1, IC2) 1 12V 1W zener diode (ZD1) 1 8200 0.25W 5% resistor 1 47Q 0.25W 5% resistor 2 .001 µF ceramic capacitors 4 220pF ceramic capacitors The PC board is installed in the case by fitting it to the three PAL sockets & then soldering the centre pins. The socket solder lugs are soldered to the ground plane on the base side of the board (tin the board first to make this job easier). Antenna components Version 1 (with steel rods) 2 double-sided PC boards, code SC02212912, 220 x 13mm 6 250mm x 1.6mm-diameter steel rods 1 2-metre length 75Q coax cable 2 75Q line PAL plugs (for antenna leads) 1 60mm length of 0.8mm enamelled copper wire 2 3.3pF ceramic capacitors 1 120mm-length of plastic sleeving for wire ends 1 500mm-length 12 x 12mm wood 1 240mm-length of 75 x 20mm wood 2 20mm wood screws 2 15mm long x 3mm diameter machine screws and nuts 2 cable clamps or cable ties 8 rubber feet Version 2 (PCB version) The external wires from the board are connected to the TRANSMIT switch & to the power socket. Check the plug polarity carefully before applying power. Start the board assembly by install. ing the 470 resistor, ZD1 and the two ICs. ZDl's anode lead must be soldered to both sides of the board, while its cathode lead should be looped to provide thermal stress relief (see photo). The two ICs should be pushed down as far as they will go and their pins soldered on the underside of the board only. Take care not to overheat the two ICs, since these are hybrid devices and are easily damaged. In fact, it's best to tin the copper pads on the board before installing the ICs, to make the soldering as fast as possible . The remaining parts are mounted on the base side of the PC board. Note that some of the component leads do not pass through holes in the PC board but simply solder direct to the pads. Keep all component leads as short as possible. The power supply leads can now be soldered to the PC board and the free ends soldered to the switch and socket. Make sure that the socket polarity is correct, with the centre pin 2 PC boards, code SC02212913, 250 x 211mm 1 2-metre length 75Q coax cable 2 75Q line PAL plugs 2 3.3pF ceramic capacitors positive as shown on the front panel label. At this stage, it is a good idea to check that the centre contact of the DC plug is also positive with respect to the outer contact. If it isn't, swap the leads around now. Inspect the PC board carefully for possible wiring errors before installing it in the case. When you are cerDECEMBER 1991 17 Fig.4: this simple 600MHz Yagi antenna consists of three steel rods soldered to a PC board, plus a feeder wire & a 3.3pF capacitor. PUSH 10mm LONG PLASTIC SLEEVING ON ALL WIRE ENDS 100 100 ALL ELEMENTS 1.6mm DIA STEEL WIRE 600MHz YAGI ANTENNA The completed Yagi antenna fits into a slot at the top of a wooden stand & can be adjusted up or down so that it points directly at the opposing antenna. tain that everything is correct, fit the board to the PAL sockets and solder the centre pins. Finally, solder the socket solder lugs to the ground plane on the base side of the PC board. Antennas Two different types of antenna can be used with the TV Transmitter, al18 SILICON CHIP though both are 3-element Yagis. The first version uses a long narrow double-sided PC board coded SC02212912, to which are soldered rods made out of piano wire [available from hobby shops) for the reflector, dipole and director. This arrangement is mounted on a wooden stand and is pivoted at one end so that the trans- mitting and receiving antennas can be pointed towards each other. The second version of the Yagi aritenna uses a large PC board coded SC02212913 and this has etched copper tracks for the elements. Although rather ugly in its appearance, this version can be easily concealed on top of a wall unit or bookcase and aimed at the opposing antenna. The antenna version that you choose is based mainly on personal preference and whether you want a free-standing unit or one that can be concealed. You could even use a different version at either end of the link. There is virtually no difference in performance between the two units. Both antennas are constructed to the same dfmensions and are designed around a centre frequency of 600MHz (near channel 37). The wavelength (lambda) is therefore 500mm. Both the director and reflector are located 0.2 lambda from the dipole, with the reflector measuring 0.485 lambda, the dipole 0.466 lambda and the director 0.458 lambda in length. If your VCR outputs at some frequency other than channel 3 7, then the antenna dimensions will have to be re-calculated to obtain the optimum range. This will not usually be a problem since many VCRs with UHF modulators can be adjusted to transmit at any frequency between channels 36 and 40. Because the 75Q feeder cable used with the antenna is unbalanced, we Fig.5: here are the dimensions for the wooden stand. The upright is slotted at the top to accept the PC board & is secured to the base using a wood screw. Although not shown here, four rubber feet should also be fitted to the base to prevent scratches to furniture or to the top ofyourVCR. 3 DIA. UPRIGHT 12x12x250 ANTENNA STANO MATERIAL : woqg Another view of the finished 600MHz Yagi antenna. If your VCR outputs at a frequency other than channel 37, the antenna dimensions will have to be adjusted to suit. SECURE UPRIGHT TO BASE WITH WOOD SCREW FROM UNDERSIDE OF BASE DIMENSIONS IN MILLIMETRES The TO TV output must be fitted with a 75Q dummy load (ie, a 75Q resistor) if the main TV is not connected. decided to use an unbalanced feed arrangement. The main advantage of this arrangement is that the dipole can be a single solid length instead of the two separate lengths required for a balanced feed. The shield of the 75Q cable connects directly to the centre of the dipole, while the centre core connects to the 75Q position on the dipole via a series 3.3pF capacitor and feeder wire. This capacitor cancels out the inductive component of the antenna connection . Building antenna version 1 The first step in building version 1 is to cut each element to the dimensions shown in Fig.4. These lengths should be made to within 1mm for best results. This done , centre each element exactly in the PC board and solder it on both sides of the board. Now solder in the capacitor and feeder wire. This wire is soldered to the PC board as shown in Fig.4 and then soldered to the dipole 25mm away. The 75Q cable can now be attached and plastic sleeving pushed over the ends of the steel rods. Don't leave the plastic sleeving off. It's there to reduce the possibility of eye injury_and to prevent the rods from snagging on clothing or curtains. Fig.5 shows the dimensions of the wooden stand used to support the antenna. It uses a rectangular base to support a 250mm-long square upright and this is slotted at the top to accept one end of the PC board. The board is then secured to the stand using a screw and nut. Tighten the nut firmly so that the antenna can still be swivelled up or down for aiming but will remain stationary after adjustment. Finally, fit four rubber feet to the DECEMBER 1991 19 a II QUALITY NO BRAND DISKETTES 5.25" DSDD 5.25" DSHD 3.5" DSDD 3.5" -DSHD $4.95 $9.30 $8 .75 $17.50 *************** JAPANESE BRAND , ':', ,,' r / 1~ FLOPPY DRIVES f ' SUPER %_ 3.5" 1.44M $99.00 / . 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"' $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 FREE PRICE L,IST UPON REQUEST . ·, ♦ 1sn -1 - THISA~~ ~.\~"' THE ~~QN\C COMP01v, '-'<;;,C SHOP 'l:1ot)'-. ~ 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 ,8 POSTAGE RATES $1 00-$9 99 ,, ,,,, ,,, $3.00 $10.00-$24 99 $3.50 $25.00-$49.99 .... $4.50 20 $50.00-$99 99 . $5.50 $100.00-$199.00 $6.00 $200.00+ . . . FREE .SILICO N CHIP FRONT OF ANTENNA Fig.6: the second version of the antenna has its elements etched into a large PC board. You simply install a 3.3pF capacitor & attach the feeder cable. underside of the base, attach the 75Q lead to the side of the upright with a U-shaped cable clamp or cable tie, and fit the end of the cable with a 75Q PAL plug. Building version 2 There's not much to building this version, since the antenna elements are already etched into the board (SC02212913). All you have to do is install the 3.3pF capacitor and attach the 75Q cable. Fig.6 shows the construction details for this antenna. Testing The TV transmitter is now ready for testing but first you must tune your second TV set to the signal from the VCR. This is best done by bring- ing the two together and connecting the RF output from the VCR to the TV antenna input with a lead. The TV set is then tuned to the VCR signal in the usual manner (ie, using a test pattern or by playing a tape). To test the TV Transmitter, connect it as shown in Fig.1 and install the two small Yagi antennas. Now apply power and check that both TV sets display the VCR program when the TRANSMIT switch is set to ON. Only the main TV set should display the picture when the switch is set to OFF. Important: if the main TV set is not connected, the TO TV output on the TV Transmitter must be terminated with a 75Q resistor (otherwise the picture on the remote TV will be a mess). This can be done by fitting a 75Q I . 5%0FF . . ' ALL ORDERS · / - _IF YOU MENTION~ 'h \ UHF CABLE * ** ** ** ** ** ** ** , .~;:1 :R :!:~~~t~ nr~ .,,;e..,,,-•~- - This version of the antenna can be hidden on top of a wardrobe or bookshelf but is not as easy to aim as the first version. TOTV INPUT (FROM VCR RF OUT) 0 OUTPUT 0 0 (TO ANTENNA) TRANSMIT OFF ON + 0 12V DC INPUT ~ =IIHD==== .,.; = = -.... ~ TV TRANSMITTER ,... ,... C\I en § C\I .=:= 0 (.) "'... C\I C\I Cl) ~ > Fig. 7: actual size front panel artwork. s'° ~ -= ~ ~ 0 "Cl ~ "' ...= "Cl '° 0 .,Q u ~ '' - "Cl ~ ::? "'d, :a = ;1 0 "Cl ~ -=... <E "'... ~ 0 i... '° ~ -~ '{' ] Fig.8: here are the full-size artworks for the double-sided PC board. Check your finished board carefully against these patterns before installing any of the parts. ... N 0== N Q) N N 0 ~ ,... '° Ol ,... .,Q oi 0b ~ resistor inside a 75Q PAL plug, which can then be plugged into the TO TV socket as the need arises. Ifit doesn't work, check the supply voltage to the OM350 ICs by measuring the voltage across ZDl. You should get a reading of 12V. If the reading is low, check the orientation of ZD1. Range The maximum range will be obtained when the two antennas are pointing directly at each other. You should have little difficulty in estab- lishing a range of about 20 metres in free space but this will be reduced if there are obstructions in the transmission path (particularly metal). Our tests showed that the prototype had a range of about 15 metres through 30cm-thick concrete-brick wall, while plaster walls had little (if any) affect on range. In practice, the range achievable should be adequate for most homes. Note that antenna placement can have a big affect on picture quality. Just moving the antenna forwards or (.) If) 0 • 0 backwards by 10-15cm can make all the difference between an unwatchable picture and noise-free reception, so it's worth experimenting. SC DECEMBER1991 21 AL TRONICS 24 HOUR EXPRESS DELIVERY 'Our customers are often amazed at the speed and efficiency of our Jetservice Courier delivery. Phone your order Toll Free 008 999 007 and presto we can deliver your order next working day (country areas 24-48 hours later). Our famous 14 day satisfaction money back guarantee protects your hard earned $$$'s should ever a purchase be unsuitable for your needs. I invite you to try Australia 's best electronics phone order service soon.' Regards, Jack O'Donnell Keyless 4 Sector Alarm Control Panel Economy Alarm Panel For Homeo and Small Commercial PramlN1 This is a 3 zone alarm control panel designed for the protection of homes and small commercial premises. It employs the latest advanced electronic circuitry offering the highest degree of quality and reliability. It will accept either active or passive normally open or normally closed sensors making it both a versatile and effective protection system . 12V battery charger inbuilt. See Altronics '91 catalogue for full details. This 4 zone panel has been suitably designed for the protection of both commercial and residential properties. It employs the latest electronic circuitry and the most up-to-date security technology. It has 4 independent individually isolatable protection circuits accepting both normally open or normally closed sensors. The panel is easily armed and disarmed via the integral inbuilt keypad . 12V battery charger inbuilt . See Altronics '91 cataloge for full" details. S54ao$129.oo s 5485 $249.oo Economical Alarm System Kit Flush/ Surface Mount Alarm Control Panel The kit comes complete with the following components: • One Alarm Panel • One Passive lnfrared Detector (P.I.R.) • One AC Power Pack • One 8 Ohm Horn Speaker • Three pairs of Magnetic Reed Switches • One 12V/1.2AH Rechargeable Back Up Battery. Feature,: • 5 Protection Circuit Loops • Independent Connections for N.C. and N.O . Sensor Switches • Arm - Disarm With 1tyll1h compact good look• thl1 alarm blend• 1moothly Into any reoldentlal or office decor. This compact 3 sector alarm panel has been designed to either surface mount or flush mount into a standard 3 gang electrical wall box. In order to provide the maximum amount of security and operation convenience the panel is operated via a 4 digit access code rather than a key. For ease of installation and service, the panel is provided with a plug in wiring harness. See Altronics '91 catalogue for full details. 3~?1\1 ~Y ::lt!t~~~•~e~bt~ad Control • Warble Tone Steady Tone Siren Driver • Adjustable Timers for Entry Delay and Siren Duration • "Latch" and "Timing" Output Relays • Remote and Local Alarm Status Indication • See Altronics '91 catalogue for full details. 55470 349 s 5490 $119.oo FREE THIS MONTH ONLY100m ROLL CABLE and 4 LARGE WARNING STICKERS WITH ANY PURCHASE OF THE ABOVE SYSTEMS • THATS A SAVING OF OVER $401 $ .oo This digital access keypad is a 12-button electronic coded combination lock. II provides two sets of secret codes for the owner. There are 11880 different combinations possible for secuirty key and 132 different combinations possible for panic. The secret codes may be instantly changed by the owner by just simply rearranging the code jumper pins on the PCB. See Altronics '91 catalogue for foll details. Super Small PI R ~ 1\"'dToOur Detector 1deallY su vel 8 VERY UNOBTRUSIVE C Uses Xenon Strobe tube for high energy flash output at a rate approx. 1 per . seconds. Fantastic light energy output for the DC power used. DC input 12V 320mA. $34.95 S 5450 Red $34.95 Blue Alarm Stickers .. Incorporating the latest technology this compact Passive Infra Red Detector (P.I.R.) features Pulse Count Triggering which virtually eliminates false alarms. See Altronics '91 catalogue for full details. 1.2AH, 12V gell cell. A quality GS product made in Japan. To suit above alarm panels. Battery Charger g~rir~:f1 !~>;Jg~A Battery Operated Portable Passive Infra-Red Intrusion Alarm High Power Car Alarm • A ready to use system , no With Wlrelett• Remote Control System offering :i~;~~~i~e• ;i~~~~:';,~~n~~~ri~t and home, shop, caravan or when travelling. r~ . ~ .00 s 5065 8020 $12.so Amazing price for en A/arm tecttttte• installation • Fully automatic operation, very user friendly • Large coverage, over 100 square metres • Portable or wall mounted • Long life 9V battery operation • Battery low Be quick. Next 1h/pmenr w/1/ be priced et M ! th••• Audible warning with a 125 decibel loud siren and visible warning of flashing headlights when the alarm system is triggered. Keyring remote control allows arming with 'beep' sound and disarming with a headlights flashing signal. The alarm system will be triggered by unauthorised entrance through the car doors, boot, bonnet or removal of the car sound unit. The siren will sound and the headlights flash for 60 seconds. Ea1y to lnltall. , car S 5220 $99 .00 I $1.9581 For your car (fixes to inside of window). 70x25mm. S 5410 $3.95 NI of 4 Backup Battery 12V s 4200 $69.95 Extra large for home. 200x75mm. s 5400 ALTRONICS SURVEILLANCE ALARM SYSTEM FITTED HERE tncredtbty Small Only 55 X 31 x 73mm S 5302 $79 .00 5065 Strobe Signal Lamps s 5455 Digital Access d To our "Keypad 1de&IIY suite I control 8020 Charger $12.50 $29.95 (see Below) Optional Accessories: • M Battery Backup • S FrH sonu• ot ,.. A/ar!_'1 511ck~nfyl Tl!II mon 111 $29.95 PHONEORDER TOLL FREE AL TRONICS 008 999 007 Pin Point Ultrasonic Cleaner Squeeky Clean Mains Filters SINGLE MODEL FILTERED DOUBLE OUTLET Awarded the Good Product Design Award for CETDC in 1987. This fantastic Ultrasonic Cleaner can earn its cost a hundred times over in cleaning Computer Connectors, PCB's, Switches, Relays, Jewellery, Glasses Watches etc. 240V :'(OC~ 570ml . tl S 1 With 3 Minute Auto Trmer Power Supply: Capacity: A 0100 $ ~ 0 0 Thi• Month Just the shot for home computer or for individually located peripherals. Eg remote printer, computer terminal etc. P815o$jj,9'.oo $99.oo ,.c~ t10-.I & $175.oo 17 Range Digital Multimeter With overload protection Our Top Selling Autoranging LCD Multimeter WithBarMemory and GraphFunction DC Voltage to 2000V 4 ranges AC Voltage to 500V 2 ranges DC current to 10A 4 ranges Resistance to 2 meg other 5 ranges Plus diode and battery tester. Includes 9V battery and probe set. Q t ■ ntaatlc 1lne/1qu ■ re Dltpl ■ y 1056 Normally great va lue at ~ 5 This month for the very quick only $39.95 a 1057 Carry Case to Suit $12.so Cut and Clinch Tool T2800 Normally $~~ Economy Rack Cabinet Thie Month Only This popular 3.5 digit Multimeter is simplicity itself. Full auto ranging on voltage and res istance measurements. The large LCD digits al low quick and efficient reading of measurements. • 42 Segment Bar Graph Display • Auto-ranging on Voltage and Resistance • Memory Mode • Low OHM Range • Hold Facility • Autmatically indicates negative inputs • Lo w Battery Indicator • Continuity check with Buzzer. Now $25.oo • Solid steel construction • Blac'< anodised front panel • 3 unit (132mm) • Conforms to International Standards• Ventilated top and side panels H 0400 only $,J.a:oo $99.oo Thll Month Only Sensational Value On UHF Alarm Systems The main control receiver runs on 240V AC with a 12V 1.2Ah battery for emergency backup. The range between the transmitters and the receiver is normally 80 metres in open space. Feature,: • Wireless reception of external and internal senso rs & detectors• Selectable home or away modes for selecting internal or external arming or just external to allow movement inside th~ building• Built in piezoelectric siren gives different signals to indicate different functions • Sends signal down power line to activate remote siren • Programmable arm/disarm switch buttons Ideal for the ,oungeroom, family room or hallways. Mounts up on the wall or bookshelf Detects movement within an area of 9 x 9m . Remote Plezo Alarm This unit is a line carrier receiver, ie . plugs into 240V AC and receives signal through AC line. Front Door Remote Keypad This handy unit virtually duplicates the function of the main contro l unit but at a more convenient location, ie. just ins id e the front or rear door etc. System can be armed or disarmed without the need to go to the main control unit. Tons of torque. Just the shot tor PCB work. 12V DC operation from optional power pack . Comes with 0.8mm and 1.0mm chucks. Plus one 1.00mm Drill BIia tor T 2320 0.8mm $3.so T 2325 1.0mm $3.50 12V 1 Amp Plug Pack Remote Reed Switch Passive Infra Red Movement Detector For PCB Work Replacement $80.oo Main Control Receiver ~ $15 PCB W ork In a 1542 $.,.99'.oo Only $69.95 Powerful 6000 RPM Mini Drill drill bit.r,i..-, T 2302 ~ .50 Thlt Month Only ■way This pocket sized oscillator has all the features of a large bench oscillator. 46 preset switched frequencies ranged from 20Hz to 150kHz, eg: 1kHz, 1.2kHz, 1.5kHz, 1.8kHz, 2kHz etc. Smaller than most multimeters, this is ideal tor technicians, servicemen , students and hobbyists who require an accurate and reliable oscillator ready to use anywhere. Q 1075 Normally • Cuts, clinches and burnishes component leads in one stroke • Burnish improves solder wetting • Lightweight and comfortable • Rugged aluminium body • Durable steel mechanism • For production or prototypes. ~-00 Tuck thlt box wave oaclllator your tool Pocket Sized, Personal Audio Signal Generator .00 SYSTEM 1 SYSTEM 2 SYSTEM 3 Includes: 1 x Ma1'l Con tro ller 3 x Re m o te Reed Sw1tc hez 1 x Remote PIA Movemen! Dete,::to r 1 x Remote Key pad 1 x Remote Siren Plus 4 Bonus Large Alarm Warning Strckers Includes: 1 ,; M an Con troller 3 x Remote Reed Switc hes Plus 4 Bonus Large A lar m Wa rni ng Stic ke rs Includes: 1 11 Ma,n Co ntro ller 1 x Remote Reed Switch 1 x Remu te PIA Movement Det ecto r 1 x Remo te ,<e y pad Pll1S .1 Bon us Large Ala r m Wa rn ing St ickers $ Thl1 Month Only 399 NORMALLYs.se- This Mo nth Only $299 NORMALLYS,636" Nicad Battery Super Sale! Rubberised Commercial Grade Heatshrink Tubing O.flnltely Au1tra//a'1 loweat prlc•• on quality Nlcadal 10+ 1-9 Normally $2.so $3.so $7.so $12.oo $12.so AA 500 mAH AAA 180 mAH 'C ' 1-8 AH '0 '4 AH Super Heavy Duty 9V (Shrinks approx 50%) The heat from your soldering iron barrel IS all that IS required With this tubing Sold by the metre. Perm 10m up $2.20 0550 $3.20 0552 $6.oo W 0554 $11.oo W 0556 $11.50 W 0558 W 0560 1.6mm (1/16") $2 .95 $2 .70 3.2mm (1 / 8") $3.45 $3.1 5 6.35mm (1 / 4") $5.10 W W 12.7mm (1 / 2" ) 19mm (3/ 4") s,►·r"1 ~ .,r,;· _:' , \) · f/ 1 W ..t.$/, Ip " ' $4.55 $5.15 $5.80 $7.95 $5.15 $6.45 $8.85 9.5mm (3/ 8") \'C'-. 8 \1\ /" // /; Bargain Hobby Packs Mixed selection $AL of above normally '7"'5 0587 W A Bargain $4.oo Microphone's Prices Slashed in Half Uni-Directional Cardioid Omni Directional Recommended for vocalist, public address & general purpose entertainment use. Frequency res: 20Hz-15KHz Impedance: 600 Ohm rnc 6M lead with phone plug and wind screen . Uses 1.5V AA battery. Recommended for recording & eminently suited for wide angle sound pickup ie: choirs, orchestras, etc. Frequency res: 50Hz-18KHz Impedance: 1 K Ohm Inc 6M lead with 6.5mm phone plug and wind screen. Uses 1.5V AA battery. Just the shot for all those 'bits and pieces' laying around! Available in three nilty sizes. Complete with partitions to custom make your own compartments. 0246 15 Way (260x175x43mm) $1O.so H 0247 6 Way (2 10x110x44mm) $5.25 H 0248 5 Way (175x95x38mm) $3.so H Attention Audloohllesl Optimise Your Sound Sy1fem With This Oxygen-Free Cable , Twin Jumbo ~~~A I! )7/llfll Twin Mega 2 5~ ~ ~ ~Go 4 W 0138 Normally $ ~ 9 5 W 0138 Normally $58.'oo Thie Month Thie Month $20 r:~ ROLL MU Metal Shielded Audio Transformers Microphone Type: Primary: 200 Ohm Secondary: 5_0K Ohm. A high quality item emmently suited to mixers, PA amplifiers and where an ultra low "hum" pickup level is desired . Cable $45 r:~ ROLL $~95 Thi• Month Only $25.oo High Quality Oxygen Free Copper 10 Up $23.oo M 0701 Normally Brid_ging / lsolating Type: Use for coupling audio modules. Prevents Aarth loops, hum etc . Essential coupling device where DC isolating is required. Nominal impedance ratio 10K: 10K (1:1). ., M 0102 Normally Thi• Month Only .;.,llll!""""lli- Audio Leads Includes mounting hardware and cable • High performance 6" x 9" 3-way speaker • Power handling 160 watts max • 4 Ohms impedance • Dome tweeter • Hi-grade barium ferrite magnet • Frequency response 50 to 22,000Hz P $16 .00 Earth Lug each end 1 .Sm $19 .SO P 0448 2 RCA & Earth Lug each end 900mm P 0448 2 RCA & c • around $600 a pair" John Negua leading WA Aud/ophlle Building that extension? What great speakers to install. Designed to install into ceilings or walls this slim profile attractive speaker system/ grille assembly will compliment any sound system. Once installed the finished unit blends beautifully into any decor. (The grille assembly can be painted over in the same finish as walls or ceilings if required) . Installation is simplified by the use of a mounting frame (which could be installed during construction) which the speaker . assembly attaches to. Full mounting kit (even screws) supplied . C0880 $)26.oo •• Thll Month'• Special $~95 $99.oo c3012$28:so Dome Tweeter With Ferro Fluid Watt Max. Power. Silky smooth frequency response 1.5Hz to 20kHz. Wide angle dispersion . Massive power handling capacity. Diam. 94mm. High spectrum. Purity. Incredible low price! 60 Plasma Lamp Display Amazing! Pulsating high voltage plasma discharge continually changes shape and direction . Mode selectable to either fingertip control or sound activated. For example, from voice or sound system . Provides endless fascination as it sizzles and arcs. Supplied complete with mains adaptor. A $99.oo .. 9334 Superb Dome Tweeter Bargain of 1991 Less Than ½ Price! High Performance 2 Way Flush Mounting Full Range 60W Speaker "'Hlghly recommended. I found It dllllcu/1 to pick the between the Aftronlca C 0880, the American System difference Sonance and 801ton Acouatlc Sy1tem1, both coating - Up$23.oo 160 Watt 6" x 9" Triaxials All Plug• and Connector, Gold Plated p04381 RCA/1RCA 1.8m $9.so 0440 2 RCA/2 RCA 450mm $11.oo p0442 2 RCA/2 RCA 900mm $12.oo p0444 2 RCA/2 RCA 1.8m $13.so 10 $,.res $25.oo 0120 Normelly ._Thie Month Only $1,,99.oo $99.oo $12.oo $1 O.oo Thi• Month 10 up Portable Gas Soldering Iron ~ Ideal Christmas gilt! No more messy and dangerous extension cords running out to the car because this iron is completely portable. Uses cigarete lighter gas. Tip temperature variable up to 400"C (or equivalent to 10 60 Natts). 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Full connection deta ils supplied with the kit. 5565 $15.95 Four Digit Combination Lock K 1 GHz Digital Frequency Meter HURRY STOCKS LIMITED THIS PRICEI SAVE $50 AT • Professional machined and screen printed red perspex front panel •Et.Sy to assemble & construct • No special Transistor FET & Zener Tester Bridge Adaptor for Stereo Amplifiers tools requ ired • Bright Hewlett Packard 8 digit display • Electronic switch latching • High performance IC' s • High qualit y componen ts . OperatH from 10-30VDC (or 81AA cetlal • Fits easil y to std . electrica l swithplate c at. electric door strike/ release cat . S 4930. NEEDS ONE OF THESE. New updated circuit incorporates facilities for testing transistors FET's and Zeners etc. K This si m ple 4 Digit Combination Lock uses o nly 3 IC 's, and is bound to prove useful in many applications. Such as accessing alarm systems. electronic doors , ignition ki llers o r ju st abou t anything that c omes to mind . 2527 Now $45 .oo Be quick llmlted quantltlH . UNIVERSITIES, COLLEGES, INDUSTRIES AND THE HOME WORK BENCH THROUGHOUT AUSTRALIA. Our superb version incorporates the latest refinements and is now housed in an attractive , tou11h "ABS" instrument case . This all new compact version has been made possible by use of a high ef ficiency toroid power transformer . So you win four ways - less heat , less weight, greatly enhan ced appearance and easier to build . GET AN AMAZING BASS IMPROVEMENT FROM YOUR STEREO SYSTEM. This fantasti c adaptor simply " samples" your st&re o amp output and prov ides a single channel o utput to feed a separate sub-woofer amp . Unwanted audio spectrum is removed with P 8040. Use with EVERY BUDDING ENTHUSIAST OR SERVICE TECHNICIAN 1000'• NOW IN SERVICE IN the Frequency Control (cu t-off thresh old adjustable 60t30Hz). • Also includes an " o u t of phase " ou tput enabling the use o f stereo amp in a bridge con figura tion for those who really want to ratt le the floorboards . $249.oo K 1925 $39.95 K 5560 $29.95 Studio 200 Series 100 Watts Per Channel Power Amplifier K 2515 ~ - 0 0 The sound quality and overall specificati.Jns o f this amplifier will compliment any sound system . The overall mechanical design and pre-drilled chass is means that this kit virtua ll y falls together and should only take the average constructor about 6 hours to build . Why pay hundreds of dollars when yo u can build it yourself and end up with a quality professionally fin ished amplifier? FEATURES: In-Built speaker protection, To1oidal Transformer (Low Hum ). Black Satin Finish , Low leakage ·power supply capacitors, Housed in Rugged Custom Chassis K 5010 Studio 200 Stereo Control Unit $425.oo Fruit Machine WIN WIN WIN WARNING THIS KIT IS VEl'IY ADDICTIVE. The Stud io 200 Stereo Control un it is companio n to the studio 200 stereo power amplifier (and other power amps) . It features slim 1 u rack mount profile, treble , ste,eo mono switch and volume control. This novel kit works just like a real poker machine but without the expense Inputs include phono, tuner, V.C.R. & tape . Virtually all components of losing money. It has a jac kpo t and mount on ~CB 's, making assembly and co nstruction a breeeze Altronics kit includes fully pr"ofessionally punched and printed Panels. five other winning combinations. GREAT AT PARTY'S K Buy Both Kits For $599 and Save 1160 $35.oo K 5015 $229.oo 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 vi rtual ly every other Australian supplier, we send goods at consignees risk . Should you require comprehensive insurance cover against loss or 174 Roe St. Perth W.A. 6000 Phone (09) 328 2199 PHONE TOLL FREE 008 999 007 MAIL ORDERS C/ - P.O. Box 8350 Stirling Street PERTH W.A. 6849 STANDARD DELIVERY I PACKING CHARGE $5.50 to 1Kg, $8 rng-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 $28.00 - We process your order the day received and despatch via Overnight JelHrvlca Courier for delivery next day Country areas please allow addItIonal 24-48 hours 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 JetHrvlca we deliver ne xt day. AL TRON ICS RESELLERS Chances are there is an Altronic Reseller right near you - check this list or phone us for details of the nearest dealer. Blue Ribbon DHlaro are highlighted wit~ a• These dealers generally carry a comprehensive range of Altronic products and kits or will order any required item for you . WA COUNTRY ALBANY BP Electronics• (098) 412681 Micro Electronics (098) 412077 BUNBURY Micro Electronics (097) 216222 ESPERANCE Esperance Communications (090) 713344 KALGOORLIE Todays Electronics ■ (090) 215212 MANDURAH Lance Rock Retravision (09) 5351246 Micro Electronics (09) 5812206 PORT HEDLAND Ivan Tomek Electronics (091) 732531 ROCKINGHAM TV Joe's (09) 5271806 NT ALICE SPRINGS Farmer Electronics (089) 522388 DARWIN Ventronics (089) 853622 VI C All Electronic Components (03) 6623506 The Electronic Component Shop a (03) 6706474 BORONIA Ray Cross Electronics a (03 ) 7622422 CHELTENHAM Talking Electronics (03) 5842386 CROYDON Truscott Electronics a (03) 7233860 PRESTON Preston Electronics ■ (03) 4840191 COUNTRY BAIRNSDALE LH & LM Crawford (051) 525677 BALLARAT Ballarat Electronics (053) 311947 BENDIGO KC Johnson ■ (054) 411411 MILDURA McWilliam Electronics (050) 236410 QLD Delsound PL a (07) 8396155 NEWSTEAD EGO Elect ron ics (07 ) 2541153 WEST END B.A.S. Audiotronics (07) 8447566 WOODRIDGE David Hall Electronics a (07) 8082777 MAROOCHYDORE MALS Electronics a (074) 436119 MARY BOROUGH Keller Electronirs (071) 214559 PIALBA Keller Electronics (071) 283749 ROCKHAMPTOt~ Access Electronics (East St. ) (079) 221058 TOWNSVILLE Super Sole x a (077) 724466 SA Force Electro nic.; .J (08) 2125505 BRIGHTON Force Electronics ■ (08) 3770512 CHRISTI ES BEACH Force Electronics a (08) 3823366 FINDON Force Electronics a (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 a (002) 342233 LAUNCESTON George Harvey a (003) 316533 NSW David Reid Electronics a (02) 2671385 SOUTH Sheridan Electronics (02) 2817727 SMITHFIELD Cha 0 tronics (02) 6097218 COUNTRY COFFS HARBOUR Coifs Habour Electronics (066) 525684 NEWCASTLE Novocastrian Elect .Supplies (049) 621358 WARNERS BAY Vilec Distributors (049) 489405 WINDSOR M & E Elect. and Communications (045) 775935 WOLLONGONG Newtek Electronics a (042) 271620. Build this infrared light beam relay 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. By DARREN YATES These days, security is a big issue. If you're running a business, then you'll know that it's impossible to keep an eye on the door at all times. A properly installed door monitor will let you know that someone has entered the shop if you're working out the back and can serve as a deterrent to shoplifting. A light beam relay can also be used to monitor sensitive areas around a business or your home, particularly where young children are involved; eg, a computer room or the access gate to a swimming pool. The SILICON CHIP Light Beam Relay is based on two common ICs (an LM324 quad op amp and an NE555 timer) and can either sound a buzzer or trigger a relay. Apart from the relay and the infrared (IR) LEDs, you will probably already have most of the parts in your junkbox. Fig.1 shows how the project works in principle. The Light Beam Relay is placed one side of the doorway and uses three IR LEDs to transmit highpower bursts of light across the doorway to a mirror. This mirror then reflects the IR light pulses back to the unit where they are picked up by an IR photodiode. Block diagram The block diagram of Fig.2 s_h ows how this reflected signal is processed. First, the detected signal from the IR photodiode is amplified by IClb and fed through a 2.ZkHz bandpass filter to extract the wanted frequency. This filter attenuates signals at all other frequencies that may be floating around, to eliminate false triggering due to noise. From there, the signal is fed to a DC WALL i______T!_!1R~AN~SM~IT!....___ _ _ LIGHT-8EAM I RELAY _ _J ----RECl~-----1 REC Fig.1: how the Light Beam Relay works. A mirror mounted on the opposite side of the doorway reflects bursts of infrared light back to a detector for processing. If the beam ·is interrupted, the alarm sounds. x121 AMPLIFIER IC1c,d INFRARED DIODE 02 2.2kHZ BANDPASS VOLTAGE DOUBLER FILTER D3,D4 MONOSTABLE AND RELAY DRIVER IC2 Fig.2: this block diagram shows how the reflected infrared light is processed. 26 SILICON CI IIP amplifier stage consisting of IClc & ICld. This amplifier has an overall gain of 121 and amplifies the small signals from the IR diode (which are in the order of a few millivolts) to a series of pulses which swing to both supply rails. The following voltage doubler stage converts these pulses to a DC voltage which is then used to control a monostable. If the pulses disappear at any time, as when someone walks through the beam, the DC voltage on the monostable trigger input drops to OV. This triggers the monostable which then turns on the buzzer or relay. Circuit details Fig.3 shows the complete circuit diagram. As you can see, there isn't a great deal to it. ICla is one section of an LM324 quad op amp and is connected as a Schmitt trigger oscillator which has a frequency of about 2.ZkHz. Diode Dl provides the .0047µF capacitor with a fast charge-up path, which results in a very low duty cycle; ie, the output at pin 1 consists of very narrow positive-going pulses. Conversely, when the capacitor is discharging, Dl is reverse biased and current flows through the 220kQ resistor tu the low output at pin 1. The output ofICla drives transistor Ql which turns on three series connected IR transmitter diodes (LEDs 13). These LEDs are driven with about 400mA of-current when the transistor turns on. Normally, this would blow the LEDs but because they are only on for about 8% of the time, the current averages out to be only about 35mA, which the LEDs can handle quite comfortably. By doing this, we can get much greater IR light output and thus much greater range than ifwe ffild them with a steady DC voltage. Again, because the duty cycle is so low, we can get away with using a BC337 transistor "' • At.ARM TRIGGERED ~f . Ne.:, -3 .,.,.i!g cz X N ... ~ ~. UGHT BEAM RELAY The circuit is housed in a low-cost plastic zippy case, with the three IR LEDs mounted on one side. A hole drilled in the case about 50mm below the IR LEDs allows the reflected light to reach the photodiode. for Ql since it doesn't have to dissipate any heat and can handle currents up to 1A. DZ is a LT536AB or similar IR photodiode which picks up the pulses ofIR light from the transmitter section of the circuit. However, the voltage developed by the diode is only in the order of a few millivolts at most. For this reason, its output is fed to IClb which operates as a high gain amplifier by virtue of the 10MQ feedback resistor connected across it (ie, it has very little feedback). The signal is then passed through a simple bandpass filter formed around the 8.ZkQ and 10kQ resistors and the two .OlµF capacitors. Because the IR diode can detect IR light that is modulated at varying frequencies, the bandpass filter attenuates all unwanted frequencies and allows our frequency of interest (ie, 2.ZkHz) to pass through. IClc and ICld are both non-inverting DC amplifier stages with gains of 11 each. These simply multiply together to give an overall gain of 121 , as shown in block diagram Fig.2 . The output signal appears at pin 14 of ICld and swings between the two supply rails (ie, ground and +12V). Diodes D3 and D4 form the voltage ~ ..J --1.--11· w a: :lE <( w m 1::z:: (!) ::i I I I ~ g L - -.....,,.,,+-l,<lf4-,,,.J,. ,. i:c 'l / I ,______..........H•· ...... C, C, I a:--./ N:aa::5 c~c:e !:; en DECEMBER1991 27 the resistance in ohms and the C is the capacitance in Farads. Power supply The circuit runs from a standard 12VDC 300mA plugpack and no regulator is required. Supply bypassing on the PC board is provided by the 100µF and 0.1µF capacitors connected across the 12V rail. Construction A cardboard light barrier must be placed between the IR LEDs & the photodiode diode (D2), otherwise light leakage from the back of the LEDs will upset the circuit operation. The leads between the board and the IR LEDs are fed through a small notch cut into the top of the barrier. doubler stage and this converts the output signal at pin 14 of IC1d into a steady DC voltage. This voltage is proportional to the peak voltage of the pulses on pin 14 and is applied to the pin 2 trigger input of 555 timer stage ICZ. ICZ is wired as a 1-second monostable. Normally, when IR pulses are present, pin 2 of IC5 is held high and the monostable is held reset; ie, its pin 3 output is low and thus the buzzer (or relay) is off. Now consider what happens when someone breaks the path of the IR light beam. When this occurs, the signal voltage at all points in the receiver circuit drops to 0V and so the .047µF capacitor at the output of the voltage doubler quickly discharges via the parallel 100kQ resistor. As soon as the voltage on pin 2 of ICZ drops below 1/3Vcc, (ie, below 4V), ICZ is triggered and its output at pin 3 goes high. This then turns on the "Alarm Triggered" LED (LED 4) and sounds the alarm at the output. Diodes D5 and D6 protect the output stage of the 555 from large negative voltages which would otherwise occur when an inductive load (eg, a relay) is switched off. Switch S1 allows the circuit to be adjusted without having the buzzer constantly going off, or can be used to disable the buzzer when it isn't required. The 100kQ resistor and the 10µF capacitor on pins 6 & 7 of ICZ set the alarm period to about one second. This period can be easily adjusted to suit your particular application by changing either the resistor or the capacitor, or both. The alarm time in seconds is simply 1.1RC where the R is Most of the parts in the Light Beam Relay are mounted on a single PC board measuring 133 x 82mm and coded SC0311291. Fig.4 shows the wiring details. Before you begin construction, check the board carefully for any shorts or breaks in the tracks. If you find any, use a dash of solder or a utility knife where appropriate to fix the fault. When you're satisfied that everything is OK, start by soldering in the wire link and the resistors. If you're not sure about the resistor colour codes, check them on your multimeter before soldering them into circuit. The remaining components can now be installed on the PC board. Make sure that the diodes, transistor, ICs and electrolytic capacitors are all oriented correctly. The IR photodiode (DZ) should be mounted about 10mm proud of the board (see Fig.3 for the pinout details). If you use the equivalent BP104 CAPACITOR CODES 0 0 0 0 0 Value IEC Code EIA Code 0.1µF .047µF .01µF .0047µF 100n 47n 10n 4n7 104 473 103 472 RESISTOR COLOUR CODES 28 0 No. Value 4-Band Code 5-Band Code 0 0 0 0 0 1 8 3 2 220kQ 100kQ 10kQ 1kQ 15Q red red yellow gold brown black yellow gold brown black orange gold brown black red gold brown green black gold red red black orange brown brown black black orange brown brown black black red brown brown black black brown brown brown green black gold brown SILICO N C/111' S1 [DJJ Fig.5: this section shows how to wire in a relay instead of the buzzer. The switched output leads can be wired to a socket. Fig.4: make sure that photodiode D2 is correctly oriented when you install the parts on the PC board (see Fig.3 for pinout details). photodiode, first install a couple of PC stakes at the diode position. The diode can then be fitted by soldering its terminals to the PC stakes. If you intend using the buzzer, it can also be mounted on the board at this stage as shown in Fig.4. If you intend using the relay instead, then refer to Fig. 5 for the mounting details. Of course, you can use other devices here provided that you don't exceed the 555's maximum drive current rating of 200mA. The unit can now be made ready for testing by wiring up the LEDs and SC03112911 the DC power socket. Use 100mm lengths of hookup wire to connect the LEDs and 50mm lengths to connect the power socket but don 't worry about switch Sl at this stage. Note that LEDs 1-3 are all CQY89 infrared types, while LED 4 is a conventional red LED. Testing Before applying power, use your multimeter to check the polarity of the plug on your plugpack supply. You should find that the tip is the positive terminal. If it isn't, then you will either have to reverse the leach; to the plug or reverse the leads from the socket to the PC board. If you h ave any doubts about supply p olarity, the best procedure is to disconnect the leads from the socket, then apply power and use your multimeter to determine which terminal is positive and which is negative. You can then connect the supply leads from the PC board to the socket as appropriate. If you do get the supply leads mixed up, the two ICs will be destroyed at switch on. Once the connections are sorted out, apply power and aim one of the transmitting LEDs at the fro nt face of the photodiode . Check that the trigger LED turns on briefly and then goes out and stays out. If you now cover the photodiode , you sho ul d find that the trigger LED now lights up and stays lit. Thi s is because the circuit thinks that someone is standing permanently in Fig.6: check your PC hoard carefully against this fullsize artwork before installing any of the parts . Etched & drilled PC boards are available from the usual suppliers. Du:1,;,\ / BEil I WI l 29 PARTS LIST 1 PC board, code SC03112911, 133 x 82mm 1 front panel label , 93 x 155mm 1 plastic case, 160 x 90 x 55mm 1 SPST switch 1 3.5mm jack socket 8 PC stakes 1 12VDC buzzer (optional, see text) 1 12V single pole relay (optional, see text) 1 12VDC 300mA plugpack 4 LED mounting bezels Semiconductors 1 LM324 quad op amp (IC1) 1 NE555 timer IC (IC2) 1 BC337 NPN transistor (01) 1 1N914 signal diode (D1) 1 LT536AB or BP104 IR photodiode (D2) 4 1N4004 power diodes (D3-D6) 3 COY89 IR LEDs (LEDs 1-3) 1 5mm red LED (LED 4) + ALARM TRIGGERED Capacitors 1 470µF 35VW electrolytic 1 10µF 16VW electrolytic 3 0.1 µF 63VW 5mm fixed-pitch polyester 1 .047µF 63VW 5mm fixed-pitch polyester 2 .01 µF 63VW 5mm fixed -pitch polyester 1 .0047µF 63VW 5mm fixed-pitch polyester LIGHT BEAM RELAY Resistors (0.25W, 5%) 1 10MQ 1 8.2kQ 1 220kQ 2 1kQ 8 100kQ 1 15Q 0.5W 310kQ Miscellaneous Hookup wire, solder, screws, washers, nuts. front of the photodiode, blocking off the beam. If everything checks out so far, the circuit is working correctly and you can install it in a plastic case. The board will fit inside any of the available standard zippy cases which measure approximately 160 x 95 x 55mm. The board is mounted on the bottom of the case using machine screws and nuts. Use the board as a template for marking out the hole positions, then drill the hol es using a 3mm drill. This done, drill three holes in one side of case to accept the mounting bezels for the IR LEDs, plus another hole that aligns with the IR photo diode. Holes must also be drilled in either end of the case to accept the DC power socket and switch Sl. Finally, drill a 30 S ILICON CHIP circular pattern of small holes in the end of the case adjacent to the buzzer to allow the sound to escape. If you decide to use a relay instead of the buzzer, delete switch Sl and substitute a socket on the side of the case for the switched relay outputs. The PC board and the other hardware items can now be installed in the case. Note that the photodiode must be optically isolated from the transmitter LEDs, otherwise light leakage from the back of the LEDs will upset the circuit operation. This can be achieve d by installing a cardboard barrier inside the case. Make sure that this barrier is a tight fit and push it all the way down onto the PC board, as shown in the accompanying photograph. The leads between the board and the IR LEDs can be fed through a small notch cut into the top of the cardboard barrier. Setting up The easiest way of setting up the project is to mount it on one side of the doorway, opposite a small mirror. It's then simply a matter of adjusting the unit slightly until the mirror reflects the IR beam back to the photodiode (ie, the trigger LED goes out). It may take you a couple of attempts to find the optimum position but it shouldn't be too hard. Finally, switch the buzzer in and check that the unit triggers for a period of about one second if you momentarily interrupt the beam. Provided the unit is correctly adjusted, it should operate reliably over distances up to 1.5 metres. SC WOOD FOR CHIPS...WOOD FOR CHIPS. .. WOOD FOR CHIPS... WOOD FOR CHIPS...WOOD FOR CHIPS... WOOD FOR CHIPS... WOOD FOR CHIPS... WOOD Why pay up to $150 for a label? Take a close look at these APPA 90 SERIES NEW multimeters. Look familiar? That's 100 SERI Es ~~~~snea~~re sold under different Look at the features • Large high contrast display • The 96 and 98 have analog bar It's called 'Badge Engineering' graphs too Appa makes the multimeter, but it' s • Colour coded input terminals sold with someone else's name on and function switch for easy it. And that means you could pay a lot more than you need to. We've setting seen the top of the line model • Probe storage clips built in tor selling at around $150 more than easy two handed measurements our price. So you're paying that • The 96 is water resistance for much extra just for the brand label' industrial use It's also an indication of how of 1.5ml good Appa meters are tharother people want to put their names on • Automatic power-off them! • Meet /EC 348 Class II and .___________ UL 1244 standards for safety • Full 12month warranty Model93 • 1999 count • Large 20mm high contrast LCD readout • 8 Functions• Vdc, Vac, Ade, Aac, Ohms, Diode, Frequency, Capacitance • 0.5% de accuracy $142 .80 $119 .00 ex tax : :~ri~~fnri~::r::/'°P • Extra tough for industrial users • High energy fuse and PTC Rroteclion against overloading • 0-ring sealed case, switch and Jacks against dirt and moislure • Protective holster and till stand with lead storage • Test probes have finger shields • !Cfc;J;;r,:~~GHscase and shock mounted LCO withstands 2m drop on to concrete 1/oor • Unique rotary switch with berrylium copper contacts and gold plated pcb Model 103 & 105 • 4000 count • Digital update twice/second, analog 20 times/sec • 8 Functions - Vdc, Vac, Ade, Aac, Ohms, Diode, Continuity, Frequency, Capacitance e Data hold & Relative functions • 0.5% de accuracy $298.80 $249.00 ex tax Ranges Vdc 400mt 4V, -lOV, 400V, 1OOOV ¼~~ 4~,168mA;~i} 750V Aac 4-400mA, 1OA Ohms 400fl, 4kn, 40kn, 400kn, 4Mn,40Mn Frequency 100Hz, 1kHz, 10kHz, 1OOkHz, 1MHz Capacitance 4nF, 40nF, 400nF, 4µF, 40µF Model 105 has similar specs but with im/i'oved accuracy of 0. 1% typ on de and 0.5% a 13i%imv, 2V, 20V, 200V, 1ooov Vac 200mV, 2V, 20V, 200Vd 750V Ade 200uA, 2mA, 20mA, 2 OmA, 2A, 20A Aac 200uA, 2mA, 20mA, 200mA, 2A, 20A Ohms 200n, 2kn, 20kn, 200kn, 2Mn, 20Mn Frequency 2kHz 20kHz, 200kHz Capacitance 2nF, 20nF, 200nF, 2µF, 20µF Also available Model 93Twith transistor tester in place of 2A range $142 .80 $119.00 ex tax Model 96 • 3 1/2 digit plus 41 segment analog bar graph • Autoranging or manual selection • 6 functions · Vdc, Vac, Ade, Aac, Ohms, Diode • Water resistant • Data hold • Memory offset ~i\_ 80 APPA35 CLAMP METER • • • • • 4000 count display Autoranging Measures to 350A ac Conductors to 25mm diameter Measures voltage to 750Vac, Ohms to 40kn and continuity with beeper • Large 12. 5mm LCO display • Oafa Hold button • Built-in belt clip 13i%imv, 2V, 20V, 200V, 1000V Vac 200mV, 2V, 20V, 200Vd 750V Ade 200uA, 2mA, 20mA, 2 OmA, 2A, 20A Aac 200uA, 2mA, 20mA, 200mA, 2A, 20A Ohms 200n, 2kfl, 20kn, 200kn, 2Mfl, 20Mfl Frequency 2kHz 20kHz, 200kHz Ca~acitance 2nF, 20nF, 200nF, 2µF, Appa 90 Carrying Case $14. 10 • 3 1/2 digit display $12.20 ex tax • Autoranging Appa 90 Holster • 7 functions Vdc, Vac, Ade, Aac, $ _ Se1x9. 2a0x 16 00 1 O_hms, Continuity • Smgl~ handed operation • Large 12.5mm LCD display • Data Hold button --- - - • Built-in probe holder $94.80 ~No~i~~ $79.00 ex tax •&~~- OµF $214.80 $179.00 ex tax Model 76 Component Tester D th th 11 t dgi:ni ,ngs yeur mu ,me er • Capacitance 200pF to 20µF • Resistance 200n to 20Mfl • Trans,st_or hie and lceo • Diode displays Vf at 1mA LED displays Vf at and 10mA • Battery tests 9V and2Ma 1.5V cells • SCR Pass/Fail test $142.80 $119.00 ex tax • . CJ ~ Fluke 70 Series II offer a lot more than 'Basic' Features All 70 series 11 Moae'ls come with the patented Fluke Touch Hold™ feature. Just probe and the meter does the rest holding readings until updated. You also get high resolution, fast autorang,ng and range hold, a quick continuity beeper, diode test, automatic selftest - even a sleeP. mode. Unexcelled Oua/1ty, Ruggedness and Support You can toss the multimeter in your toolbox confident that it'll be g~ci~~J~/~ii!'~i~fi~~~~~~ci~~~t~rn overloads - voltage to 1000Vdc or 750Vac. All current ranges are protected with high energy fuses including the 10A range.l'lus you have a world-wide service network Common features Automatic TouchHold™ • Diode Test • Audible continuity• Au toranging with manual ranging• TL75 Test Leads with Hard Points™• Sleep mode• For measurements to 4800V·A 70 3200 count digital display• 31 segment analog bar grapll • 0.5°/, basic Vdc accuracy• 2.0% basic · Vac accuracy • 0.5% basic resistance accuracy • 2000 hour battery life (alkaline) $146.00 $125.oo·ex tax 73 As 70 but 0.4% basic Vdc accuracy • 2.0% basic Vac accuracy• 1.5% basic de current accuracy (1 OA range only) • 0.5% basic resistance accuracy• Holster/Flex-Staggttl.OO $175.00 ex tax 75 As 73 but with additional current range 32mA to 10A $312,00 $260.00 ex tax egi~'/Jimv, 2V, 20V, 200V, 1000V Vac 200mV, 2V, 20V, 200Vd 750V Ade 200uA, 2mA, 20mA, 2 OmA, 2A, 20A Aac 20011A, 2mA, 20mA, 200mA, 2A, 20A Ohms 200f!, 2!<fl, 20kn, 200kn, 2Mfl, 20Mfl $166.80 $139.00 ex tax Model 98 • 3 1/2 digit plus 41 segment analog bar graph • Autoranoino or manual selection • 8 Functions • Vdc, Vac, Ade, Aac, Ohms, Diode, Frequency, Capacitance · • Data hold • Memory offset $299.00 ex tax ~ Fluke - The Ultimate 2"6 r ~ ~ () ;!; il fJ> Fluke 83 Handheld Multimeter • 0.3% basic accuracy • Min/Max average recording • Duty cycle, capacitance, frequency • Zoom bar graph, x10 • Relative measurements Measures volts, amps, checks continuity and performs diode tests, measures frequency,_duty cycle and capacitance. The minimum, · maximum and average values can be recorded simultaneously. Analog bar graph updates at 40 times per second and the input Alert™sounds a constant audible warning or wrong input connections. 3 Year Warranty Brief Specifications DC Voltage 400mV to 1000V AC Voltage400mV to 1000V DC Current 400uA to 10A AC Current 400uA to 1OA Resistance 400n to 40Mfl , 40nS Other Functions Continuity threshold <20fl Capacitance: 5nF to 5uF Frequency: 0.5Hzto >200kHz Diode Test: Displays voltage t~rg8 0.1 % lo 99.9% 1OOms and 1s mode $478.00 $399.00 ex tax Fluke 85 Handhel d Multimeter 8 All Fluke 83 Features PLUS • 0.1 % basic accuracy e 20kHz bandwidth $576.00 $480.00 ex tax Fluke 87 Handheld Multimeter e All Fluke 85 Features PLUS • 4 1/2 digit mode • 1ms peak Min/Max recording • True rms measurements • High resolution 128 segment analog pointer • Backlig hting with time-out $690.00 $580.00 ex tax Fluke 45 Dual Display Digital Multimeter • 100,000 count, 5 digit multimeter • 0.0,% de accuracy (1 year) • Multi-function Dual display measures two signal parameters from a sing le test connection and allows you to view both measurements at the same time • Closed case calibration • Standard RS-232 and optional IEEE-488 • 21 reference impedances for dB measuremen ts Next to its dual display, the Fluke 45's powerful features include true rms ac + de voltage measurement, frequency measurements to 1MHz, compare (limits) functions, TouchHold ™, relative and Min/Max, i~ti~;tti'a8r~chargeable bagfz5ing0 $1216.00 ex tax Geoff Wood Electronics Pty Ltd ~ ~ () ;i;; ~ ~ ~ () ;;i:; ~ ~ CJ ~ () ;;i:; ~ ~ CJ ~ () ;;i:; r § CJ ~ ~ r ~ Brief Spec ifications DC Voltage 1oomv to 1ooov (1µV Resolution) AC Voltage 100mV to 1000V DC Current 30mA to 1OA AC Current 1OmA to 1OA Resistance 100n to 300Mn Frequency: 5Hz to 1MHz Diode Test: Continuity, capture time 50µs dB:Reference ,mpedance 2n to Skil (inc in N s W) 229 Burns Bay Road, (Corner Beatrice Street), Lane Cove West N SW Mail Orders to - PO Box 671, Lane Cove N SW 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 add $5.00 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. cl ::0 2 '6 f'l § cl ::0 () ;;i:; r § ~ () ;;i:; lJ fJl VINTAGE RADIO By JOHN HILL Power supplies for battery receivers Early radio receivers up until approximately 1927 were battery-operated with very few exceptions. They used a variety of different batteries, including dry & wet cells and rechargeable & non-rechargeable types. The late 1920s saw a market trend away from battery-operated receivers to "all electric" models that used household power. These electric radios were much cheaper to run and allowed many people to own a receiver in circumstances where they previously may not have been able to afford the high cost of battery operation. However, not all households had electric power and battery radios were manufactured until the end of the valve era, even if they mainly took the form of portables in those latter years. I live in country Victoria and it is surprising the number of old battery sets that are still around. Perhaps one in every six pre-1 950 receivers I find is a battery model. Most of these sets haven't been used for 30 years or more and have often been stored in a shed or a farmer's barn. Personally, battery receivers don't interest me greatly and their general level of performance is only fair when compared to mains-operated sets. A battery output valve such as a 1D4 is rated at 0.35 watts. When compared to the 4.5 watts of a 6V6, the advantages of mains operation are fairly obvious . Despite my lack of enthusiasm for battery radios , there are several in my collection and there is a GE vibrator model in the shed awaiting restoration. I'm not so one-eyed that I pretend that battery sets don't exist! The main problem with batterypowered receivers today is the lack of suitable batteries, for it has been many years since they were made. Even if they were still available, the price would be prohibitive. The battery eliminator Back in the 1920s, there was a handy radio accessory called a "B" battery eliminator. Even today, an eliminator is a handy thing to have if one is into battery receivers. There were several different types of battery eliminators. Some were "B" eliminators only, while others also produced "C" battery voltages. More recent types produced "A" voltages as well. A breakdown of these "A" , "B" and "C" batteries may be helpful for readers unfamiliar with battery receivers. The "A" battery's function is to supply the low tension current to the valve filaments. Typical battery valve filament voltages range from 1.5V to 6V. The author's home-built 1A regulated power supply and the accompanying small "B" battery eliminator will power most battery receivers. 32 SILICON CHIP The "B" battery supplies the receiver's high tension current and is applied to the plates and screen grids of the valves. "B" batteries were usually made in 45-volt units (sometimes with a 22,5V tapping) and were used singularly or in twos or threes , depending on the specifications of the recei~er. Three large "B" batteries producing 135 volts was a fairly common high tension requirement for many battery receivers. Finally, the "C" battery supplies the negative bias to the control grids of the valves. There is virtually no load on a "C" battery - it only supplies a negative potential to the control grids. "C" batteries were usually either 4.5V A "B" battery eliminator solves most of the problems of operating old battery radios. Shown at left is an Emmco eliminator of1927 vintage while immediately above is a close-up view of the controls. This unit has three outlets, two of which are variable. Some eliminators also had a range of "C" battery voltages. or 9V types with tappings. An old original · One of my battery sets is a 1938 model which still had its "C" battery installed in a special battery holder when I bought it. The interesting aspect of this battery (possibly the original) is that it is still in use today. Unfortunately, the old "C" battery was not dated but it is old enough for the cells to be sealed with sealing wax, which suggests that it has been around for quite a while. The design of the Eveready trade mark it carries is similar to those shown in mid-1930s radio books. When checked with a voltmeter, the old 4.5V battery measures 4.44V but when short-circuited, it is so weak that it cannot even manage a lmA discharge. However, as the "C" battery's only function is to give the control grids a negative potential, this ancient battery still performs its task quite .well. How one gets side-tracked; let's get back to battery eliminators. A simple "B" battery eliminator will solve the most serious problem of operating battery radios. Finding 135 volts DC is difficult if one thinks only in battery terms. If a "B" battery eliminator cannot be found, a home-made version can be built using a suitable transformer and a rectifier (either valve or solid state power diodes). Add suitable filtering and the appro- This home-made power supply is used with a small 2-valve headphone receiver. The "A" battery consists of two "D" cells, while the 90V "B" battery consists of ten 9V transistor batteries. priate high-voltage electrolytics and bingo, you have a "B" battery eliminator. If you are repairing an old "B" eliminator, the capacitors will most likely need replacing to restore it to full working order. "A" batteries are not much of a problem to substitute. Dry cells or rechargeable nicads are OK for receivers with 1.5V or ZV valves. A wirewound rheostat in the circuit will help to control the voltage. The old triode valves from the 1920s with their 4V and 6V filaments need a higher supply voltage. A small 6V motorcycle battery will do the job nicely and a suitable rheostat (about Z0Q) will knock back the voltage for use with 4V valves. A rechargeable 6V motorcycle battery is also a good power supply for any battery radio with a vibrator unit. Most vibrator radios operated from a single 6V supply rail, although some required a 4V or 32V rail. Typically, a small lead-acid battery will keep a vibrator set operating for three or four hours. Low-tension receiver voltages can also be supplied by regulated power supplies. A regulated power supply produces a virtually ripple-free current which is most desirable for battery valve filaments. A poorly filtered DC filament supply can cause considerable hum in the loudspeaker. A regulated power supply can also be used as a "B" battery eliminator if it is capable of producing sufficient voltage. A simple 1-valve regenerative receiver often works quite well DECEMBER1991 33 Rechargeable "B" batteries were not all that popular as they were messy, smelly and expensive to buy. The unit shown here has 12 cells and is rated at 24V. (Photo courtesy Orpheus Radio Museum, Ballarat). on 30V, which is well within the capabilities of many power supplies. Other options There are also other power alternatives for battery receivers. Last month's Vintage Radio dealt with the building of a 2-valve regenerative receiver. This particular receiver is typical of the simple homebuilt radios that so many of us oldies built in our youth. Like the receivers in this month's story, the 2-valve regenerative receiver is also battery operated. This particular radio uses two size "D" dry cells connected in series to light the filaments. A rheostat reduces the supply to 2V. The "B" battery is formed by using five 9V transistor batteries connected in series. These little batteries can be This 1938 AWA receiver is a 4-valve battery set which performs quite well. Many battery sets are worth collecting and they are much more interesting if they are in working order. 34 SILICON CHIP joined using their own snap connectors, soldered together or mounted in a special battery pack as shown in one of the photographs. Although this "B" battery is quite small compared to the large 45V batteries of yesteryear, its capacity is more than adequate for the task. The little two-valver draws just one milliamp of high-tension current when the receiver is operating. This rate of consumption is only a fraction of what the battery would be subjected to if it were used in its intended role in a transistor radio. The 90V "B" battery shown in another of the photographs has had quite a bit of use and most of the batteries in it are six years old. Only two have been replaced in that time. Despite the battery's age, it still delivers irt excess of 80 volts under load. Dry cell shelf-life is very good these days. Modern batteries are sealed very well and the electrolyte does not dry out. What's more, the purity of the zinc used in their manufacture is also better than in the past. This reduces the amount of "local action" which slowly destroys the cell from within. I have an 11-year old "Sharp" AA cell that still tests OK under load. Rechargeable batteries In bygone days, when battery-operated receivers were the norm, re- This old Diamond 45V "B" battery came with a 22.5V tap. Three of these batteries were used in the AWA receiver shown at left to give a 135V high tension supply. (Photo courtesy Orpheus Radio Museum, Ballarat). Resurrection Radio Vintage Wireless Specialists 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. Despite being many decades old, this 4.5V "C" battery still delivers close to its rated voltage. "C" batteries were used for grid bias in early battery sets. chargeable lead-acid "A" batteries were quite popular. These batteries required charging at regular intervals. If the household didn't have mains power, then the rechargeable battery had to be taken to the local garage or radio service centre for its weekly or fortnightly charge. Less common was the rechargeable "B" battery and this item, with a charger, would probably have cost as much as the average receiver did in the 1920s. My father built a rechargeable "B" battery back in the 1920s. It was charged direct from the DC mains using a globe in series with it to control the charge rate. Rechargeable batteries were large, heavy, seepy, smelly things and a good many users must have been very pleased to trade them in on a mainsoperated receiver. The Air Cell One "A" battery worthy of mention was the "Air Cell", and battery receivers from the 1930s era were often powered with this unique device. This cell used a carbon/zinc element combination, with an electrolyte of caustic soda (sodium hydroxide, NaOH) in water. It developed 1.4V on no load, dropping to between 1.2V and 1.3V under typical loads. A battery consisted of two cells and , as purchased, the cells were sealed and contained the dry caustic soda. The battery was activated by breaking the seals and adding water. The name Parts are available for the enthusiasts 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 catalogue. WANTED - Valves, Radios, etc. purchased for CASH Call in to our Showroom at: 51 Chapel Street, Windsor,Vic 3181 PO Box 1116 Telephone: (03) 529 5639 A 45 volt "B" battery can be made simply by connecting five 9V batteries in series as shown here. Such a battery has quite a long service life when used with a 1 or 2-valve receiver. "Air Cell" was given to this unusual device because it used oxygen from the atmosphere as a depolarising agent for the positive electrode. When used with a 2V filament string, a small amount of resistance ranging from 0.6-1. H1 was needed for typical current drains. A single Air Cell battery could operate a 7-valve receiver (filament consumption 550mA) for 1100 hours. By contrast, 36 No.6 dry cells at twice the cost were required to operate the radio for a similar period. In spite of this , the Air Cell wasn't around for very long and this was due to a number of factors. One was the high initial outlay which many people simply could not manage, even though it was cheaper to operate in the long run. It also had to compete with the 2V accumulator which, even if less convenient, was more economical for many people. Another factor was the timing of its appearance. Battery valve design was evolving rapidly, particularly in the area of operating economy, and eventually lead to the 1.4V-type valves , which were designed specifically for dry cell operation. At the same time, the vibrator-type receiver, powered by a single large 6V accumulator, was gaining popularity as the supposed answer to the whole battery problem. But regardless of the type of batteries used, battery receivers were costly to run and the power supply took up a considerable amount of space. Many early radios had quite sizable compartments in them to house batteries, while others were built on doublestorey trolleys , with the lower shelf used entirely as a battery storage area. The mains-operated electric models must have had great appeal when they appeared. SC DECEMBER 1991 35 Silicon Ch'i:p , BACK ·coPl"E S\ July 1988: Stereo Control Preamplifier, Pt.2; Fitting A Fuel Cut-Off Solenoid; Booster For TV & FM Signals; The 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 Of Nicad Batteries; Data On Insulated Tab Triacs. September 1988: Hands-Free Speakerphone; Electronic Fish Bite Detector; High Performance AC Millivoltmeter, Pt.2; Vader Voice; Motorola MC34018 Speakerphone IC Data; National Semiconductor LM12 150W Op Amp Data & Applications; What Is Negative Feedback, Pt.4. (Uses Mosfets); Poor Man's Plasma Display; Automotive Night Safety Light; Adding A Headset To The 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/Demister 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; Simple Computer Sound Repeater; 120W PA Amplifier (With Balanced Inputs) Pt.1; How To Service Car Cassette Players; Massive Diesel Electrics In The USA; Marantz LD50 Loudspeakers. October 1988: Stereo FM Transmitter (Uses Rohm BA1404) ; High Performance FM Antenna; Matchbox Crystal Set; Electronic House Number; Converting A CB Radio To The 28MHz Band; Queensland 's Powerful Electric Locomotives. February 1989: Transistor Beta Tester; Minstrel 2-30 Loudspeaker System; LED Flasher For Model Railways (uses LM3909) ; Bu ild A Simple VHF FM Monitor (uses MC3362), Pt.1 ; Lightning & Electronic Appliances ; Using Comparators to Detect & Measure. November 1988: 120W PA Amplifier Module March 1989: LED Message Board, Pt.1 ; 32-Band Graphic Equaliser, Pt.1; Stereo Compressor For CD Players; Map Reader For Trip Calculations; Amateur VHF FM Monitor, Pt.2; Signetics NE572 Compandor IC Data; Electronics For Everyone Resistors. April 1989: Auxiliary Brake Light Flasher; Electronics For Everyone: What You Need to Know About Capacitors; Telephone Bell Monitor/ Transmitter; 32-Band Graphic Equaliser, Pt.2; LED Message Board, Pt.2. 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. June 1989: Touch-Lamp Dimmer (uses Siemens SLB0586); Passive Loop Antenna For AM Radios; Universal Temperature Co ntroller; Understanding CRO Probes; LED Message Board , Pt.3. Use this handy form to order your back copies l ---7 ----------------------------------Please send me a back issue for: D November 1988 D April 1989 D September 1989 D February 1990 D July 1990 D December 1990 D May 1991 D October 1991 D October 1988 D March 1989 D August 1989 D January 1990 D June 1990 D November 1990 D April 1991 D September 1991 July 1988 December 1988 May 1989 October 1989 March 1990 August 1990 January 1991 0 June 1991 D November 1991 D D D D D D D D August 1988 D January 1989 D June 1989 D November 1989 D April 1990 D September 1990 D February 1991 D July 1991 D D D D D D D D September 1988 February 1989 July 1989 December 1989 May 1990 October 1990 March 1991 August 1991 Enclosed is my cheque/money order for $______or please debit my: D Bankcard Card No. $5.00 each (includes p&p). Overseas 9rders add $1 each for postage. NZ orders are sent air mail. Signature _ _ _ _ _ _ _ _ _ _ _ _ _ Card expiry date_ _ /_ _ Detach and mail to: SILICON CHIP PUBLICATIONS PO BOX 139 COLLAROY BEACH NSW 2097 Name _ _ __ _ _ __ _ __ _ _ _ _ _ _ _ _ _ _ __ __ Street _ _ __ _ _ __ _ _ __ _ _ _ _ _ _ _ __ _ __ Suburb/town _ _ __ _ _ _ __ __ _ _ _ Postcode _ _ _ __ _ D Visa Card D Master Card Or call (02) 979 5644 & quote your credit card details. Fax (02) 979 6503 X I - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - I_ 36 SILICON CHIP Channel Mixing Desk, Pt.2; Using The UC3906 SLA Battery Charger IC. April 1990: Dual Tracking ±50V Power Supply; VOX With Delayed Audio; Relative Field Strength Meter; 16-Channel Mixing Desk, Pt.3; Simple Service Tips For Your Microwave Oven; Active CW Filter For Weak Signal Reception. May 1990: Build A 4-Digit Capacitance Meter; High Energy Ignition For Cars With Reluctor Distributors; The Mozzie 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. 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; Studio Series 20-Band Stereo Equaliser, Pt.1; Garbage Reminder - A 7-Day Programmable Timer; Introduction To Stepper Motors ; GaAsFet Preamplifier For The 2-Metre Band; Modern 3Phase Electric Locomotives. September 1989: 2-Chip Portable AM Stereo Radio (Uses MC13024 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). October 1989: Introducing Remote Control; FM Radio Intercom For Motorbikes (Uses BA 1404 & TDA7000) 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. June 1990: Multi-Sector Home Burglar Alarm; Low-Noise Universal Stereo Preamplifier; Load 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. 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. 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; The Tube Vs. The Microchip (Two Shortwave Receivers Compared); What To Do When Your Computer Goes Bung, Pt.4. 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. October 1990: Low-Cost Siren For Burglar Alarms; Dimming Controls For The Discolight; Surtsound Simulator; DC Offset For DMMs; The Dangers of Polychlorinated Biphenyls; The Bose Lifestyle Music System; Using The NE602 In Home-Brew Converter Circuits. 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. 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. January 1990: Service Tips For Your VCR; Speeding Up Your PC; Phone Patch For Radio Amateurs; High Quality Sine/Square Oscillator; Active Antenna Kit; The Latest On High Definition TV; Speed Controller For Ceiling Fans; Designing UHF Transmitter Stages. December 1990: 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. 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. 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; Electric Vehicles - The State Of The Art. March 1990: 6/12V Charger For Sealed LeadAcid Batteries; Delay Unit For Automatic Antennas; Workout Timer For Aerobics Classes; 16- February 1991: Synthesised Stereo AM Tuner, Pt.1; Three Inverters For Fluorescent Lights; Low- Cost Sinewave Oscillator; Fast Charger For Nicad Batteries, Pt.2; How To Design Amplifier Output Stages; Tasmania's Hydroelectric Power System. 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 Config.Sys & Ansi.Sys; High-Voltage DC Transmission Systems. April 1991: Steam Sound Simulator For Model Railroads; Simple 12/24V Light Chaser; Remote Controller For Garage Doors, Pt.2; 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; Motors For Electric Vehicles. June 1991: A Corner Reflector Antenna For UHF TV; Four-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 1991: Battery Discharge Pacer For Electric Vehicles; CD Error Analyser, Pt.1; Loudspeaker Protector For Stereo Amplifiers; Four-Channel Lighting Desk, Pt.2; How To Install Multiple TV Outlets, Pt.2; Tuning In To Satellite TV, Pt.2; PEP Monitor For Transceivers; The Snowy Mountains Hydroelectric Scheme. 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 ($1000 Satellite Ground Station Reviewed); Installing Windows On Your PC; StepBy-Step Approach To Vintage Radio Repairs . September 1991: Studio 3-55L 3-Way Loudspeaker System; Digital Altimeter For Gliders & Ultralights, Pt.1; Build A Fax/Modem For Your Computer; Ultrasonic Switch For Mains Appliances; The Basics Of AID & DIA Conversion. October 1991: Build A Talking Voltmeter For Your PC, Pt.1; SteamSound Simulator Mk.11; Magnetic Field Strength Meter; Digital Altimeter For Gliders & Ultralights, Pt.2; Getting To KnowThe Windows PIF Editor. 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; Modifying The Windows INI Files. 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 issues out of print, 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. DECEMBER 1991 37 RITRON POWER RITRON QUALITY c2~6 .. t~ ASSEMBLED & TESTED IN AUSTRALIA $1 ,239 80286-16 CPU 1 MEG RAM EXPANDABLE TO 4 MEG 21Mhz LANDMARK SPEED TEST 1.2M JAPANESE BRAND F.D.D 42M 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) 2 SERIAL, PARALLEL, GAME PORTS 3 YEAR " AUSTRALIAN " PARTS & LABOUR WARRANTY 256K VGA CARD. IBM• COMPATIBLE SPREADSHEET, WORDPROCESSOR & DATABASE SOFTWAREINCLUDED. TAX INC. ASSEMBLED & TESTED IN AUSTRALIA $1 269 ' (386SX-27) ( •. . 386-57) /;;!.~ '/Jill 80386SX-20 CPU EXP TO 4 MEG 27Mhz LANDMARK SPEED TEST 1.2M JAPANESE F.F.D. 512K VGA CARD 85M HARD DISK DRIVE, 18ms ACCESS 101 EXTENDED " CLICK" KEYBOARD CASE & 200W POWER SUPPLY SUPA VGA COLOUR MONITOR (1024 x 768 Resolution) SERIAL PARALLEL GAMES PORTS 3 YEAR "AUSTRALIAN"' PARTS & LABOUR WARRANTY IBM• COMPATIBLE SPREADSHEET, WORDPROCESSOR & DATABASE MINI SOFTWARE INCLUDED. • SHAREWARE SOFTWARE $1 499 ' TAX INC. ASSEMBLED & TESTED IN AUSTRALIA. 80486SX-20 CPU 64K CACHE ON BOARD MEMORY 1 MEG RAM EXP TO 32 MEG 75Mhz LANDMARK SPEED TEST 85 MEG HARD DISK 18ms ACCESS TIME 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 Resolution) MINI CASE & 200W POWER SUPPLY 3 YEAR "AUSTRALIAN" PARTS & LABOUR WARRANTY SPEADSHEET, WORDPROCESSOR & DATABASE SOFTWARE INCLUDED. 'SHAREWARE SOFTWARE ASSEMBLED & TESTED IN AUSTRALIA. TAX WITH 200 MEG DRIVE TAXEX. 80386-33 CPU 128K CACHE ON BOARD MEMORY 1 MEG RAM EXP TO 16 MEG 57Mhz LANDMARK SPEED TEST 85 MEG HARD DISK 18ms ACCESS TIME 1.2M JAPANESE BRAND F.D.D 101 EXTENDED "CLICK" KEYBOARD SERIAL PARALLEL GAMES PORTS SUPA VGA COLOUR MONITOR (1024 x 768 Resolution) MINI CASE & 200W POWER SUPPLY 512K VGA CARD (256 COLOURS) IBM" COMPATIBLE 3 YEAR "AUSTRALIAN" PARTS & LABOUR WARRANTY SPEADSHEET, WORDPROCESSOR & DATABASE SOFTWARE INCLUDED. •SHAREWARESOFTWARE ASSEMBLED & TESTED IN AUSTRALIA. $1 895 ' ASSEMBLED & TESTED IN AUSTRALIA. TAX INC. $2,195 ~t; $1,875 TAX EX WITH 200 MEG DRIVE $3,195 TAXINC. $2,685 TAX EX. TAXEX. G486~tts) ( 486-75 ) $2,035 C•· •·• ~.a §f.7.p•• • • • •® 80386-40 CPU 128K CACHE ON BOARD MEMORY 1 MEG RAM EXP TO 16 MEG 650Mhz 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 Resolution) MINI CASE & 200W POWER SUPPLY 3 YEAR "'AUSTRALIAN"' PARTS & LABOUR WARRANTY SPEADSHEET, WORDPROCESSOR & DATABASE SOFTWARE INCLUDED. •SHAREWARE SOFTWARE RITRON EXECUTIVE EXECUTIVE INC. EXECUTIVE $1,650 RITRON ' DOS 4.01 AN EXTRA................ 60 DOS 5.01 AN EXTRA................ $100 TAX INC. RITRON RITRON 1 MEG RAM PLEASE NOTE SYSTEMS _DO NOT COME WITH DOS. $1,120 TAX EX. RITRON EXECUTIVE $2 395 ADD PRICE TO BASE SYSTEM COST. 512K VGA CARD ..... ............ ..... $50 IM VGA CARD ......................... $150 TO CHANGE A 40M HARD DRIVE TO A 85M HD add ........................ $150 126M HD add .......................... $290 200m HD add ......................... $700 EXTRA RAM 1 MEG add ........................ ; .. $75 add ........................... $150 >D 80286-12 CPU 1 MEG RAM EXPANDABLE TO 4 MEG 16Mhz LANDMARK SPEED TEST 1.2M JAPANESE BRAND F.D.Q 42M 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) SERIAL, PARALLEL, GAME PORT 3 YEAR ·'AUSTRALIAN"' PARTS & LABOUR WARRANTY 256K VGA CARD. IBM• COMPATIBLE SPREADSHEET, WORDPROCESSOR & DATABASE SOFTWARE INCLUDED. OPTIONAL EXTRAS RITRON RITRON $3,295 TAXINC. $2,850TAXEX. 80486-25 CPU /,;!~)J(Jill ON BOARD CACHE. 1 MEG OF RAM 115Mhz LANDMARK SPEED TEST 85 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 VGA COLOUR MONITOR (1024 x 768 Resolution) MINI CASE & 200W POWER SUPPLY 3 YEAR" AUSTRALIAN"' PARTS & LABOUR WARRANTY SPREADSHEET, WORDPROCESSOR & DATABASE SOFTWARE. $2,895TAXINC. $2,495 TAX EX. ROD IRVING ELECTRONICS Est. 1977. MAIL ORDER HOTLINE: 008 33 57 57. (ORDERS ONLY) ENQUIRES: (03) 543 7877 HEAD OFFICE: 56 RENVER RD, CLAYTON. PH: (03) 543 2166. FAX (03) 543 2648 CITY 48 A'BECKETT ST. MELBOURNE. PH. 663 6351 / 6391640. FAX : 6391641. OAK LEIGH 240C HUNTINGDALE RD OAKLEIGH. Ph: 562 8939 NORTHCOTE 425 HIGH ST. NORTHCOTE, PH. 489 8866. FAX: 489 8131. SYDNEY:74 PARRAMATTA RD, STANMORE. PH: (02) 519 3134. FAX: (02) 519 3868 MELBOURNE DEALER: BLUESTAR COMPUTERS : 271 MAROONDAH HWY, RINGWOOD, 3134. PHONE: (03) 870 1800 FAX: (03) 879 3927 WITH 200 MEG DRIVE $3,595 $3,055 TAXINC TAXEX 80486-33 CPU 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 VGA COLOUR MONITOR (1024 x 768 Resolution) TOWER CASE & 220W POWER SUPPLY 3 YEAR "'AUSTRALIA N"" PARTS & LABOUR WARRANTY SPEADSHEET, WORDPRCESSOR & DATABASE SOFTWARE. ASSEMBLED & TESTED IN AUSTRALIA. IDEAL CAD MACHINE! TAX INC. $ ■ :Zffi Postage rates $1 - $9.99 ...... $3.00 Theae poetage $10 • $24.99 .. $3.50 rate• are bHlc poetage only up to $25 • $49.99 .. $4.50 5Kg. Road freight, $50 - $99.99 .. $6.00 bulky & fraglle $100 • $199 ... $7.00 ltemewillbe $200 - $500 ... FREE $500 PLUS ... FREE :;.::,d, ~!,.. 9 3 '7 5 $3,295 TAXEX. All sales tax exempt orders to : RITRON ICS WHOLESALE 56 Ronv., Rd, Clayton, Victoria. Ph: (03) 543 2166 Fax: (03) 543 2648 MAIL ORDER & CORRESPONDENCE P.O BOX 620, CLAYTON, VICTORIA. 3168. Error• & omm,aeone exeep&ed. Pricee & apeclftc1Uon1 aubJect to change. •1BM, PC, XT, AT, are reglatared b'ademerila of lntamadon.al Bualne■- Machlnee. 1 1-9 boxes 10+ 31/2"0D $19.95 3 1/2"HD $45.95 5 1/4"DD $14.95 5 1/4"HD $23.95 OXES OF TEN ISKS LIFETIME WARRANTY 1-9+ 10+ 50+ 100+ 500+ 5 1/4" 5 1/4" 31/2" 3 1/2" DSIDD $4.75 $4.50 $4.30 $4.10 $3.90 DS/HD $8.75 $8.50 $8.20 $8.10 $7.50 DS/DD $8.50 $7.90 $7.70 $7.50 $6.90 DS/HD $16.50 $15.90 $15.50 $14.75 $13.90 $18.95 $42.95 $12.95 $22.95 3 1/2"DD $28.50 3 1/2"HD $53.50 5 1/4"DD $22.95 5 1/4"HD $27.95 $27.95 $52.50 $21.95 $26.95 3 1/2"0D $23.95 3 1/2"HD $39.95 5 1/4"DD $12.95 5 1/4"HD $19.95 $22.95 $37.95 $11.95 $18.95 HARD DRIVES ~ 85 MEG HARD DISK FOR AT •·tJMi:lit+1;111 m¥Wli•1ill Ill 28ms ACCESS WITH IDE/FDD CONTROLLER FAST STEPPER .......... $549 18 ms ACCESS WITH IDE/FDD......-=.,.,,-, Y AR CONTROLLER VOICE COIL.. .. WARRAN"l"Y •• $459 42 MEG HARO DISK FOR AT 126 MEG HARD DISK FOR AT 16ms ACCESS WITH IDE/FDD WARRANTY YEAR CONTROLLER VOICE COIL.. ............... $675 28 ms ACCESS WITH IDE/FDD CONTROLLER FAST STEPPER .......... $329 CH11'1li00•1ctt=c§•]!•i<at>;J•1•1Mt11ms ACCESS WITH IDE/FDD 200 MEG HARD DISK FOR AT 12ms ACCESS WITH IDE/FDD y AR WARRAN"l"Y CONTROLLER VOICE COIL. .............. $1,095 YEA CONTROLLER VOICE COIL. ...:~~~~~.:: .. $349 Al! Hard Disk capacities are formatted. IDEiFDD drives are already low level formatted so you only have to "F DISK" to high level format them. Please note you need DOS 4.01 to format these to their maximum capacity as drive "C'' or otherwise you will have to partition as "C", "D","E:", etc. if you have an earlier version. DOS 5.0 UPGRADE 3 1/2" or 5 1/4" AVAILABLE ................ ONLY $115 AUVA 945/20 RITRON 486-33 MAIN BOARD The Auva 945/20 takes up less space than your old desktop when your working and can be stored In the drawer of your desk when finished. The Auva 945/20 wont drag you down when you need to be on the go. It weighs only 3 Kgs. SPECS: Keyboards: Int&rnaI 83-key keyboard Microprocessor: CPU 80386SX-20 1 o function keys Memory: Fitted with 4Mb 1/0 Ports: External 15 i:,in VGA 8I0S: 128KB ROM Pheonix BIOS analogmonltor port, Centronics 25·pln Storage Devices: One 1.44MB 3.5" parallel port, Extarnal 5.25" floppy floppy disk drive connector One 60MB 2.5" Hard Drive Weight: 3 Kg including battery Display: VGA compatible display 640 x 480 plxal resolution 32 grey scales Backlit Paper White LCD extax • Intel 80486 Microproce&1or • IBM, XT and AT • Direct support for the Weitek 4167 coprocessor • Built-ln cache controller: Optional 32-KB, 64-KB, 128-KB or 256KB cache memory • 128Kcache fitted. , Supports interleaved cache RAM for high speed CPU . as well as 80486 burst mode . • Flexible DRAM 1-32MB , Sophisticated DRAM controller , AMI BIOS with built-ln SETUP program • Support shadow RAM • Synchronous AT bus clock with programmable clock • Support fast A20 Gate & fast CPU reset to boost performance of software utilizing 80486 protected mode, such as OS/2, UNIX..etc. • Eight expansion slots - Six 16 bit, Two 8-bit $3495 X18131 ..........................................................$1,795 31 /2" DRIVE KIT. Y.E DATA 3.5" 1.44n20/360 DRIV ~ E,Q !'/ • 5 1/4" Mounting bracket • Power supply adapter ,~ , • Cable adapter • ·~ • Floppy dis.k contr~ller car.d which3.co ~~rols 1.44".~/360 driveste E . th h. he , Complete 1nstructIons to install a 5 in your existing compu r. n1oy e 19 r density & easy handling of 3.5" floppy diskettes I C11915 .................. .$295 I , $2950 ,MATH CO-PROCESSOR SPECIALS . 80287XL... replaces 80287-6 80287-8 80287-10 .............. $295 80387DX-33.................... • .....................................$595 80387SX-16................... • .....................................$450 80387SX-20................... .. ....................................$495 LOOK! NEW CARDS "MegaRAM" Memory board 4 PORT SERIAL CARD This new generation memory enhanced board offers O wait state high speed operation. It can tske up to 6MBytea of 4 x 256K or 1 x 1M DRAM chip. Up to 7 cards can be used together (42MB 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, 16 bit configerable. So get yourself a Mega for the price of a Mini. Xl BQ.51 ............. ................................. - .......................................... .......$299. 00 (Software Output cables Included.) The PE-514A has 4 serial ports for asynchronous communication. These ports can be used to conrlllct your PC with • serial printer, MODEM, serial mouse or other aerial devices which uae an RS232C Interface. The interface is• DTE type with a male DB25P for 4 aerial port oUlpUl It supports DOS & XENIX. X18155 .........$199 ROD IRVING ELECTRONICS Pty. Ltd. ACN.005 428 437 HEAD OFFICE : 56 RENYER RD, CLAYTON, PH: (03) 543 2166. FAX (03) 543 2648 CITY 48 A'BECKETT ST. MELBOURNE. PH. 663 6351 /6391640. FAX: 6391641 . OAKLEIGH 240C·HUNTINGDALE RD OAKLEIGH PH:.562 8939 NORTHCOTE425 HIGH ST. NORTHCOTE, PH. 489 8866. FAX : 489 8131. SYDNEY:74 PARRAMATTA RD, STANMORE. PH: (02) 519 3134. FAX: (02) 519 3868 BLUESTAR COMPUTERS: 271 MAROONDAH HWY. RINGWOOD. PH: (03) 870 1800 Postage rates $1 • $9.99 ...••. $3.00 pootago $10 - $24.99•. $3.50 ralao a111 bulc $25. $49.99.. $4.50 pootage onty up to $50 • $99.99.. $6.00 ~•;:g'::lgh~ $100-$199 ... $7.00 ltamow!Ube Th•• !~rky $200 • $500•• •FREE charged at different $500 PLUS .. FREE rataa . TOLL FREE MAIL ORDER HOTLINE: 008 33 5757 . 'SLOG SERVIC When the ghost comes early In the spiritual sense, ghosts are not usually expected until after the main event; ie, after someone has departed this life. It's usually the same with TV ghosts. Normally displaced to the right, they are caused by signals which arrive after the main signal. I'm not all that well versed in spiritual ghosts but I have heard stories, from those who delve into such phenomena, about ghosts that appeared earlier than normal (ie, while the person was still alive). Admittedly, even the believers concede that this is very rare - compared with normal ghostly appearances, that is. OK, so my cynicism is showing. And I must admit that I tend to be trifle cynical also about early TV ghosts - leading ghosts, that is. Oh yes , I know they do happen; I've seen them but, like the spiritual early ghost, they are quite rare. So what causes a leading ghost? Until now, I have seen only one mechanism ; one where the TV signal finds its way directly into the tuner. Since the signal from the antenna takes a finite time to travel through the cable, it will arrive later than the signal picked u p directly by the tuner. And , the longer the antenna cable, the greater the ghost image displacement. The TV set will normally lock onto the stronger sync pulses so, if the signal from the antenna is the stronger (as it would be n9rmally), this signal will produce the "main" visual image and will be centred on the screen. The weaker image then becomes the ghost, whether it is leading or lagging. I once saw a classic example of a leading ghost. In TV's early days, a colleague had been involved in installing a large distribution system in a motel on Sydney's north shore, almost literally in the shadow of the transmission towers. The system had been run with coax 40 SILICON CHIP cable throughout, so it was a shock when all the sets produced leading ghosts. The cause was eventually traced to the sets' physical layout. The tuners were mounted at the front of the chassis, with about 30cm of soon ribbon running to the antenna terminals at the rear. And the ribbon was the culprit; in the shock area, it was picking up a substantial signal. Shielded cable cured the problem. Even rarer than the leading ghost is a ghost generated by the TV set itself. I am less familiar with these but a colleague has encountered a few. The exact mechanism is unclear but most TETIA TV TIP Philips GR100 chassis Symptom: no sound. Picture is perfect c:1.nd all other functions work correctly but there is no response from the volume control. Cure: this chassis features a "hotel" mode which allows the hotelier to silence noisy sets in rooms occupied by inconsiderate guests. The function can sometimes be triggered unintentionally by spikes on the mains. The cure is easy. Simply select Channel 38 with the remote control, then press "Store" and "Control +" together. 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. are caused by a fault in the IF strip. The suggestion is that it is due to some kind of frequency dependent phase shift, whereby the higher frequency video signals (ie, the fine details of the image) reach the video detector before the lower frequency video signals and sync pulses. Another cause experienced by this colleague was a faulty luminance delay line, in an early colour set. The delay line was an inductor about 12cm long and 9mm diameter, over which was a metal strip, forming one plate of a distributed capacitor. The fault was due to a faulty chassis connection to this metal strip. And what about an internally generated leading ghost? Well, nobody seems to have heard of that one. Until now. The ghostly Mitsubishi · The set involved was a an AWA Mitsubishi model SC6601, sold by a dealer colleague about nine months previously and thus still under warranty. The owner rang me first, complaining that the set had developed bad ghosting. And it was clear that he firmly believed that the set was at fault. Naturally, I was sceptical, not only in the general sense but because of the customer's location. There was a multi-level department store being erected at a nearby shopping centre, with the usual assortment of tall cranes reaching skywards. This had prompted a swag of complaints, both to me and as letters to the local newspaper, about interference to TV reception in the area. The construction company, while sympathetic, could do little to help. But they did advise that the cranes would probably be gone in a few weeks and that, hopefully, this would ease the problem. So, on this basis, I advised the customer to wait and see what happened. If the problem persisted, I would get one of my antenna and I are pretty adept at such jobs, so together we manhandled it into his van and delivered it to the workshop. Initial checks lI Q] \ t 1 ! ONC~ SAW A.. C.l.A4S"SI C. eJ<AM'Pl-E OF ~ C-£ADIN6 GHOST":., installation colleagues to have a look at the setup. The next thing I heard, about a fortnight later, was from the dealer. Apparently the owner was becoming impatient and had contacted him about the problem. Fortunately, the dealer was about to make a delivery in that area, so he took the opportunity to call. And he was smart enough to take another small set with him. This check was most revealing, because the dealer's set produced a virtually ghost-free picture. And that meant that it was an internally generated ghost, which put an entirely different complexion on things. My dealer colleague suggested I visit the customer's home, check his findings and perhaps fix it on the spot. "No way", I replied. "No way am I going to tackle an internal ghost problem in the customer's home. It's going to be hard enough in the workshop. We'll have to bring it in". I used the word "we" advisedly because I knew why my colleague had suggested I go to the customer's home. This is a 65cm set although, in most cases, I can usually handle sets of this size alone, albeit with a bit of puff and grunt. But not this one. It was housed in an enormous cabinet; the kind that normally needs a couple of furniture removalists to shift it. Well, almost. In fact, my colleague Two things had emerged from the visit to the customer's home. One was his discovery that the problem was intermittent - which didn't cheer me up at all. The other was that the two images were displaced by about 1520mm and that they were of almost equal intensity. I didn't even try to rationalise this last effect at this stage; time enough when I had it on the bench. So I set it up and fed in a signal from the pattern generator, choosing a simple one consisting of a circle, a cross and a border. It has no cross hatch and is ideal for observing ghosts and also for centring the picture. Now, with a steady pattern, I realised that one signal was slightly more intense than the other and had assumed the main signal position at centre screen. But the weaker image was to the left of the main image; in other words, a leading ghost. This was a bit of a shock initially but, on reflection, I decided that it was probably of more academic interest than anything else. If the previously expounded theory was to be believed, it simply meant that the high video frequencies were arriving ahead of the sync pulses. This might mean something to the set's designer but it meant little to me in practical terms. In fact, I had very little to go on, apart from the above secondhand experiences. I didn't even have a manual for the set and so I phoned AWA and was assured that one would be despatched immediately. And they were as good as their word - except that, somehow, the circuit diagram had been omitted. It took another phone call to get that. Unfortunately, I found that it left a lot to the imagination but more of that later. Three suspects By now I had mentally designated three s-qspect areas: the tuner, the IF strip and the luminance delay line. I put the delay line at the bottom of the list. According to my colleague, the displacement he encountered due to this cause was minimal and was more akin to a bad case of ringing than the marked displacement that I was observing. DECEMBER1991 41 SERVICEMAN'S LOG - CTD After that, I tended to favour the IF strip but decided to eliminate the tuner first, since it was easy to do. I simply reset the generator to the video IF (36.875MHz) and injected this signal into the IF pack. The result was totally conclusive; the ghost was still there and the tuner was cleared. Unfortunately, there were a couple of problems with the IF strip. The circuit showed this simply as a box, with 11 terminals, marked VIF-Pack. And the chassis itself was just as coy; the pack was a metal box, about 73 x 50 x 25mm, with 11 terminals. And it was tucked in•between two vertical boards on the lefthand side of the main board. Getting it out was more tedious than difficult but it was eventually done. When I opened the box I found it to be a typical IF system; a transistor, a SAW filter, an IC and a few discrete components, all on a small board. The intermittent nature of the fault (which I had confirmed) suggested a possible dry joint, and this was my line of attack. I went over the board with a glass and found not one but three obvious dry joints, which I repaired. I then put everything back together, refitted the box in the set, rubbed my hands with satisfaction (/) . R 42 The right track I did this and found myself talking to a technician who was obviously familiar with the problem. As far as he was concerned, I was right; the problem was in the IF strip. Well, that was some encouragement. Having checked what I had already done, he went on to suggest the joints of several other components. One of these was the SAW filter and another a small trim pot (the AGC preset). In addition, there were three other small components which, without a circuit, I couldn't identify. These were mounted on the copper side of the board and were probably small capacitors. I would have liked to have discussed the theory of the problem in detail but there was little more that he could tell me. So I pulled the pack out again and checked these components. The trimpot connections were above suspicion but, in any case, I doubted whether it could be responsible for this fault. The joints of the other three small components were equally above suspicion. That left the SAW filter. The SAW filter has five connections, two being to the chassis. And, having been alerted, a more de tailed check did suggest that some of them were rather "iffy". I resoldered them all, checked the rest of the board again, and refitted the pack. I put the set through another series of exhaustive bench tests and it performed faultlessly. After about a week, I concluded that the ghost had been finally laid and so the set was returned to the customer. A recent • check, two month's later, revealed that all oooAN'D INOUl-'D '<OIJ 'B~Uf:\JE. \ , ; 11.\G:' was well. However, the phrase ONLY 'PAN\At:>~ WP.S ~ T\N'< C.\·\\? OF\= mE: CA'e>\Nf;"f"ooo ~!!{p (fi; and switched on. You beaut! - no ghost. I let it run for several days, switching it off and on occasionally, and it didn't miss a beat. But then I left it off for a couple days and, when I switched it on again, there was the ghost - but for about 30 seconds only. I ran it for several more days, switching it on and off, thumping and otherwise abusing it. No ghost. I left it off for a couple of days and tried again. And again, the ghost appeared for 30 seconds at switch on but nothing more. At this point, I decided that, rather than waste more time, it would be better to fit a new IF pack, seeing that the set was under warranty. So I rang the company's spare parts department to order a replacement pack. They were out of stock but expected new stocks in about two weeks. Well, that was OK, the dealer had loaned the customer another set and a couple more weeks shouldn't matter. But the two weeks dragged on into four and when I rang I was told that there had been a delay in supplies from Japan and that it could be several more weeks - or even longer before stocks arrived. The company was both apologetic and helpful, suggesting that, if the worst came to the worst, they would "borrow" a pack from another set. But they suggested that I first talk to the service department, in case there was still a chance of repairing the existing unit. . .,, SILICO N CHIP "returned to the customer" in the previous paragraph has a deeper meaning than its simplicity implies. It was a near disaster. I've already mentioned the bulk of this set and the need to have two people to move it. Well, when it came time to return it, the dealer who had helped me bring it in could not immediately spare the time to help again. I explained the situation to the owner who was quite happy to help at his end, so I shanghaied a colleague into helping at my end. The snag was, the owner had his own ideas on carrying the set. He insisted on going first - which was OK by me - but also on walking forwards, supporting the set behind his back. Years of experience have taught me that this is a risky practice; it is simply not possible to get as secure a grip this way as it is when facing the load. Granted, one needs to make sure that there is a clear path and to check out steps, doorways and other obstructions but, on balance, facing the load is the safest way. I suggested I go first but this was ruled out. So we started up the concrete path to the one step leading to the house. The path was smooth and level but the edges had been finished with a raised roll, about 75mm high. All went well until he reached the step at which point, for some unexplained reason, he stumbled. What happened next was all over in milliseconds. He lost his grip on the left side of the set - the front - so the face of the picture tube was heading for the raised edge of the path. I suppose it was pure instinct which made me do what I did, because there was no time to think. I lifted the right hand side of the set with all the force my arm could muster. And it worked; I rolled the set through 180° and also pushed it beyond the path. It landed on the top of the cabinet, legs ·in the air, on the adjacent grass. And would you believe it; the only damage was a tiny chip off the cabinet veneer at one corner. There was no internal damage. But it was too close to an oops for my liking. A genuine oops And finally, here's a genuine oops. The first part of this story occurred long before I came on the scene but this is how I pieced it together. It concerns an up-market stereo amplifier, a Technics model SU-V460 made by Matsushita. This amplifier is rated at up to BOW per channel and has all the usual bells and whistles dear to the heart of the audiophile at a price somewhere between $700 and $800. It had been sold by my dealer colleague only about 18 months previously and, by all accounts, the customer was very happy with it. Or at least he was until the night of the party. The details of the party are a bit vague - nobody was saying much, even if they could remember, which is probably understandable in the circumstances. However, there was a broad hint that the party was what one might term an unofficial one - that the owner and his wife were away and "while the cat's away, the mice will play" the "mice" being the teenage offspring, mates and girlfriends. Anyway, someone managed to overturn a glass of drink on top of the amplifier. After which it didn't go. And so the owner took it back to my dealer friend, sheepishly confessed that something had been spilt into it, and asked what could be done about it. My friend removed the cover, took one sniff at the inside, and nominated Coca Cola. He then suggested that he should pass it over to me, as an authorised Panasonic Service Centre. But no; the owner insisted that it be returned directly to Panasonic, to ensure that the job "was done properly". (Bit of a blow to my ego, that). And so this was done. But it received short shrift at Panasonic. It came back with a brief note saying that the unit was not worth repairing; it would be cheaper to buy a new one. Naturally, the owner wasn't very happy but at least he accepted the diagnosis. And, in retrospect, I'm thankful that it was Panasonic that delivered the verdict, rather than myself. I wonder whether he would have taken my word as readily as he did their's. And that softened the blow to my ego somewhat. It was at this point that I first learned of these happenings, mainly because my dealer friend was stuck with the relic, and was about to send it to the tip, when it occurred to him that it might be of some use to me. He was TV TEST EQUIPMENT (AUSTRALIAN MADE) SHORTED TURNS TESTER Built-in meter to check EHT transformers including split diode type, yokes and drive transformers. $78.00 + $3.00 p&p * * * * * * * * * DEGAUSSING WAND Strong magnetic field , larger than usual coil with multicore centre. Double insulated for your safety. Also fitted with momentary on/off switch. 240V AC 2.2 amps. Just about as important as having a soldering iron in your toolbox! $75.00 + $10.00 p&p * * * * * * * * * HIGH-VOLTAGE PROBE Built-in meter reads positive or negative voltages from 0-50kV. For checking EHT and focus as well as any other hi-tension voltages. $98.00 + $5.00 p&p LOW-VOLTAGE PROBE Ideal for checking microwave ovens & TVs. The ranges are 0-5kV ·negative & 0-10kV positive. Double insulated for safety . $84.00 + $5.00 p&p * * * * * * * * * REMOTE CONTROL TESTER (INFRARED OR ULTRASONIC) Designed to test inlrared or ultrasonic control units. With the extension lead you can also test inlrared units which cannot be placed in front of the testing unit. Requires a 9V battery. Output is via a LED and piezo speaker. $84.00 ~ $4.00 p&p . ·.· .· ·, ♦', >;:.., / · ~- TUNER REPAIRS ./..r. ~ . From $19 exchange ~ . - plus p&p ...._ ~ - ✓ P,~.~~--- Cheque, Money Order, Visa Card Bankcard or Mastercard 216 Canterbury Road, Revesby, NSW 2212. "'2:r (02) 774 1154 .·-...!!!!(02) 774 1154 DECEMBER 1991 43 SERVICEMAN'S LOG - CTD Fig.1: general layout of the SU-V460 amplifier, showing the output stage heatsink, with the amplifier output IC (SV13205) on the front of it. It was in this area that the Coca Cola landed. aware that I had been thinking about such a piece of gear and that I might be able to salvage if I could afford to put some time into it. The idea intrigued me too. Without for one moment questioning Panasonic's diagnosis, I felt there was a fair chance that it might be possible to restore the amplifier for a modest amount, in my own time. And I already had a manual for it. And so it finished up in the workshop. I pulled the covers off and began assessing the damage. It was a mixed bag; there was not much to be seen at first glance but closer inspection soon revealed the details. This unit has a large main board (about 300 x 220mm) sitting on the bottom of the cabinet. Among other things, it carries the driver stages and the output IC for the power amplifiers. This output IC is mounted on a large finned heatsink which in turn is mounted above a central cut-out area measuring about 200 x 90mm. And it was on this heatsink and the surrounding board that most of the Coke appeared to have landed. The preamplifier and frequency control stages, along with the switches and other controls, are on a separate front panel board. They appeared to have escaped serious contamination. Vaporised links The output IC - IC501, SV13205 connects to 18 terminal pads on the board, along one edge of the cutout area. And this was where I first found obvious - and quite startling - dam44 SILICON CHIP age. Four of these terminal pads, 3, 4, 5 & 10, are connected to other parts of the board via short wire links. In fact, pins 4 & 5 are connected to 45V rails, while pin 10 connects to a 15V rail. Or, more correctly, they should have been so connected. In fact, some links no longer existed; they had been completely vaporised - a dramatic indication of just how violent the reaction had been. There were other links nearby which had also suffered, although not so drastically; these had simply melted, leaving most the wire in place. From here, I turned my attention to a group of 16 transistors on the main board - Q451 to Q465 - which make up the amplifier input and driver stages. There had been some violent reactions here also. Some of the transistors had been literally blown to pieces; all that was left were the legs with a few scraps of black encapsulation clinging to them. Of those physically intact, an insitu meter test indicated that most were faulty, while the others were doubtful; which meant that they would all have to be replaced. And, iri the same area, there were a number ofresistors which had obviously been badly overloaded. At this point I decided to make a rough estimate as to the cost ofreplacing those components that were obviously faulty. A quick check with Panasonic revealed that the output IC (IC501) would cost well over $100. Add to that the 16 transistors, sundry resistors known to be damaged, plus allowance for components not yet checked, and there wouldn't be much change out of $200. Well, OK, an $800 amplifier for $200 (plus the labour ofreplacing the faulty bits) doesn't sound such a bad proposition. But was that all that was involved? On closer inspection, I real 7 ised that it was not. Between the 18 pads and tracks feeding the output IC, I discovered considerable carbonising of the board. Now, it is usually possible to correct this situation by gouging out the charred material and is always worth a try where it is only minor and there is little other expense involved. As I say, it usually works; but not always. But this situation was quite different. The charring was extensive and the. space between tracks quite limited. And it would be impossible to know whether the work had been successful until I had bought and fitted some $200 worth of components. And this was only on the basis of the known faulty components. There would almost certainly be more and, in particular, I was worried about those on the front panel board. These included three ICs, various switches and potentiometers, plus a swag of minor components, any of which could have been damaged in one way or another. This would add to the cost but, even if this was only minor, there would also be the time needed to track them down, which could be quite tricky. And if one of them was intermittent, it could take a considerable amount of time to track down. The upshot of all this was that I had to shake my head and push the thing aside. What had initially looked like an attractive idea was simply not a practical proposition. I have recounted this story for a couple of reasons. The most obvious one, of course, is to emphasise that electronic devices and beverages do not mix. Such devices should not be located where people - and particularly inebriated party guests - are tempted to use them as a table. The other point is to vindicate the original diagnosis by Panasonic. Customers often accuse service organisations of taking the easy, and more profitable, course of writing off a device, when a repair really is economically possible. Well, perhaps it does happen. But not with reputable organisations. 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This unique product simply plugs into the end of your existing house hold vacuum cleaner hose and away you go, Supplied with: • an adaptor to suit all vacuum cleaner hoses ~ ~ • • • • • 1 x 80cm clear flexible tubing 1 x straight and curved extension pipe 1 x oval brush ' 1 x round brush 1 X crevice tool. ·x.· JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR .. e - ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS ELECTRON ICS - - n - e o .. no JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR , •n = ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS o on ~j:~g:: s JAYCAR JAYCAR JAYCAR JAYCAR s JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAY CAR - JAYCAR 4'-------•--...,- -j:~g:: ................ - ~ - ••••liiiiill., 110U1m IIRUSH _ __, .11 JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR 1S JAYCAR IS JAYCAR S JAYCAR 1S JAYCAR .S JAYCAR S JAYCAR S JAYCAR S JAYCAR S J AYCAR 'J AYCAR JAY CAR ljllllii6ililllliiiil...• OIAL IRU'" $14.95 c o :r Mi•-··-- '4 ATTRACTIVELY GIFT BOXED JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR 2.7A 6.5A 24A 38A $8.95 $14.95 $16.95 $16.95 $20.00 $29.95 $32.95 $43.50 $99,95 $149.95 S S S S S S S S S S S S S S S S S S S S S S s S S S S S S S S S S S S S S S S S S 1s 1S IS 1S 1s ALL THIS FOR ONLY h r1stm~s 6V 6V 6V 12V 12V 12V 12V 12V 12V 12V $12.95 Normally $1 3 9 ECTRO ECTR ICS JAYCAR ICS JAYCAR ICS JAYCAR ICS JAYCAR ICS J AYCAR 1A 6Ah 8A 156 x 112mm Pkt 24 Cat XL-2505 Great for cleani ng computers, typewriters, office machines, stereo and video equipment etc. Cat XV-5060 ~ _~ . 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This kit shows you how to make a solar system. make asolar circuit • make an electrical circuit • kearn how to increase vollage • learn how to increase current • learn how to make asolar panel • use solar power to produce energy for a radio, calculator, ballery charger and1.SV cassette player. The kit includes 8 solar cell s which fit into apl astic housing and can be connected up in either series or parallel, a motor and mounting bracket, afan, lool for connecting solar cells and a10 page booklel - - - - - - - - - - - - - - - - - ~ explaining thewhfs andhow's of solar energy. Cat. KJ-6 692 NORMALLy $24. 95 ~ _ ~ ~ ::~ ~t~g;~g: • JAY JAY JAY JAY JAY 'AY .9uce $20 SOLAR EDUCATION KIT AY AY AY AY AY AY AY :~ :AR ELECTROI Now yo u can experi ment wi th solar energy - the energy source of lhe future. Our solar :AR ELECTRO! education kit is designed to let you build your own solar models. This kit comes :AR ELECTROt :AR ELECTROt co mplete with: :AR ELECTROt • Solar cell module • Solar energy bookle t explaininr, the why's and how's of solar :AR E' ,=CTROt energy• small DC motor • screws and nuts • wire with moto r cli ps• coloured :AR ELECTRO! sp inner di scs • paper aeroplane and bird models • plaslic tumlables wilh 4 sizes, AR ELECTROf AR ELi:C TR Of 5/8' , 1', 11 /2' and 2· • plastic fan spinn er. AR ELECTROf cat. KJ -6690 AR ELECTROf 1 AR El :CTRm AR ELECTROf -AR ELECTROf AR ELECTROf AR ELECTROf AR ELECTRO~ -AR ELECTROf ·AR ELECTRO~ -AR ELECTROf Keep your car battery trickle charged while ii is parked for This is a smalli ead with a90 socket on oneend to a9 way AR ELECTROf These batteries are encased in black plastic housing which extended periods. sized 15 pin D pl ug (with only 7 pins connected). Length 10cm AR ELECTROf meas ures 30(L) x 16(W) x 19(H)mm. They were removed from AR ISTA'$ PRICE $14.95 cat. MB-3503 AR ELECTRO~ prin ted circuit boards by simply cutting ott the PCterminals so to A\ Cat. PL-0876 AR ELECTRO~ A\ usethemyou would need to break open the plastic case. Inside AR ELECTROf A\ are two 1.2V cells. So purchase 4 of these, 1 cell and you -AR ELECTROf A\ .AR ELECTROf have 8.2V (9V216 lype) battery for only $4, not about $20. Ideal A\ -AR ELECTRO~ for hobbyists, experimenters, elc. To buy these today they would A\ AR ELECTROf A\ cost about $13each. AR ELECTRO A\ :AR ELECTRO~ Cat. SB-2470 A\ .AR ELEC TRO~ A\ .AR ELECTRO~ A\ :AR ELECTROf A\ :AR ELECTROf A\ :AR ELECTROf A\ :AR ELECTROf A\ :AR ELECTRO~ Used In TV's, roll surrounds and arequality. Oval speaker, A\ :AR ELECTROf rubber roll surround. Size: length 68mm, width 34mm, _ h eight A\ :AR ELECTROt 33mm. Impedance 7n. Power hand IIng 1 watt. A\ :AR ELECTROt A\ :AR ELECTRO! Cat. AS-3020 A\ :AR ELECTRO! A\ The solar panel in lhe lld will charge up to 4 x AA NI Cads In a :AR ELECTRO! A\ :AR ELECTRO! This Is aquallly power supply. II is 240V pri mary to 48V DCat fairly short time. A\ :AR ELECTRO! 1.SA and 75V AC 50Hz at 6VA. It is housed in alarge melal cat. MB-3502 A\ :AR ELEC TR O! enclosure measuring 300(L) x 140(W) x 1 OO(H)mm. It A\ :AR ELECTRO! incorporates two transformers, fuseholder and spare fuse, 2 x A\ :AH ELECTRO! A\ :AR ELECTRO! 2500uF63V can electros, rectifier board and two large vollage A\ :AR ELECTRO! resistors. The inputs and outputs are all screw terminal strips. A\ :AR ELECTRO! Al last a low cost quality, portable butane powered flame torch. Ideal for the These would have cost Telecom afortune to be made. Due to the A\ :AR ELECTRO! hobbyist and professional. Adjustable flame, completely portable, up to 90 enormous weight- we must ask mail order customers to add an A\ :AR ELECTRO! minutes use per fi ll, adjustable temperature control, mini size, uses standard A\ extra $5 on top of normal P&P charges. :AR ELECTRO! butane gas lighler fuel. Ideal for shrinking healshrink tubing. A\ :AR ELECTRO! Cal. MP-3032 A\ :AR ELECTRO! Cat. TS-1410 Soldering option Cat. TS-1412 A\ :AR ELECTRO! A\ :AR ELECTRO! A\ :AR ELECTRO! A\ :AR ELECTRO A\ :AR ELECTRO A\ :AR ELECTRO! A\ :AR ELECTRO! A\ ;AR ELECTRO! :AR ELECTRO! ;AR ELECTROt ;AR ELECTROt 240V mains to 15V AC 100mA. Supplied with 2 melre cable to a :AR El.::CTROt ;AR ELECTROt 2.1mmDC plug. Cat. MP-3022 ;AR ELECTROt :AR ELE CTROt Buy aspare at this silly low price. :AR ELECTROt ;AR E'. .,CTROt Consists of a mini antenna which is :AR ELECTROt onl y 470mm(about 18') tall which is ;AR ELECTROt top adjusted and aquality magne ti c ;AR ELECTROt :AR ELECTROt basewith 5 feet of cable and aCB :AR ELECTROt plug. We've had reports lhal lhis ,;AR ELECTRO t anlenna is as good as a4foot helical ;AR ELECTROt bul you be lhe judge. You would ;AR ELECTRO! ;AR ELECTRO! expect to pay around $35 - $40 for ;AR ELECTRO! this , bul not from Jaycar. Limited :AR ELECTRO! quantity. ;AR ELECTRO! ;AR ELECTRO! Cat. DC-2020 ;AR ELECTRO! ;AR ELECTRO! ;AR EcECTROI ;AR ELECTRO! ;AR ELECTRO ;AR ELECTRO I :AR EcECTRO \Y _:;TRON ICS JAYt;AH c LECTR ONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRON ICS JAYCAH cLcC I HUNI\;::; JAYCAH t:Lt:C I HUNI\;::; JA YU\H t:Lt:L, I HUNIL," JAY ECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRON ICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRON ICS JAYCAR ELECTRONICS JAY ECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAY ECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELEC rRONICS JAY ECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ~LECTRONICS JAY NORMALLY $9. 95 ~~.9"uoe>$7.95 SAVE $2 SOLAR CAR BATTliiRY BOOSTER ~~ VARTA NICad BATTERY MADNESS 2.4V 100mA/h a adanto• NORMALLY $29.95 .9uce $20 SAVE $9.95 ~-~ .9uce $1 ea QUALITY SMALL SPEAKER SOLAR BATTERY CHARGER NORMALLY $14. 95 ~ .9uu$10 SAVE $4.95 WAS $ 3 . 9 5 . ~ .9uce $2.50 10+ 90~ ea 100+ 75~ ea TELECOM POWER SUPPLY BARGAIN BUTANE MINI TOOL SAVE $2.90 Plug Pack BARGAIN NORMALLY $9.95 , 1 ONLY $1 ea 100 up $2 ea X'MAS SPECIAL BUY BOTH FOR $20 STOCK UP NOW ONLY remove CB ANTl!NNA WITH MAGNETIC BASE BARGAIN $4.95 WAS $19.95 NOW $14.95 ONLY $:55 Nalural Natural Natural Black Front Panel Height 44 88 132 44 Mounting Boll Centres 34 57 89 34 lnlernal Chassis Height 38 82 126 38 $65.00 $79.50 $89.50 $65.00 Black Black 88 132 57 89 82 126 $79.50 $89.50 Cal No Finish HB-5411 HB-5413 HB-5415 HB-5410 HB-5412 HB-5414 $58.50 $71.55 $80.55 $58.50 $71.55 $80.55 REMOTE CONTROL BY BOB YOUNG Motors for electric flight models This month, we will discuss the electric motors used in model aircraft & look at controller requirements. In coming months, this will lead to a construction article for an electronic speed controller. Two prototypes of the electronic speed controller are being developed and these will be test flown in a twin Partenavia P68 Victor. This aircraft is shown a photo accompanying this article, along with my old mate and builder of the model, Wes Fisher. Before we can begin to design this unit however, we must have a full understanding of what is expected from an electronic speed controller for modern electric motors. Electric propulsion is an old dream of modellers and appeals especially to those in the modelling fraternity who abhor the noise and mess of internal combustion motors. Burnt castor oil is one of the most obnoxious substances one will meet in the hobby game. It is almost impossible to remove completely from your hands or models and over a period of time will gradually soak into a balsa airframe, rendering it very difficult to repair. Internal combustion technology has greatly improved over the past few years, with synthetic oils which allow much higher methanol/oil ratios .and are very easy to clean off. Fourstroke motors are now available too. These use much less oil, deposit less oil on the model and are much quieter in operation. We also have super glues which work well for bonding oily surfaces and we now have fibreglass which is impervious to the ingress of all oils . However, the appeal of electric propulsion remains undimmed by this impressive catalog of technological wizardry. If anything, it is enhanced (or some would say even finally made possible) by a similarly impressive catalog of technological wizardry peculiar to the field of converting electricity into mechanical energy. At the very heart of this mini technological revolution are dramatic improvements in battery and magnet Shown here is a reversing speed controller made technology. Thus, we some years ago by Sunlux. It was a 12V device rated 15-20 amps. now find ourselves in an era in which model electric motors are capable of delivering staggering performance by the standards of not too long ago. What's more, we also now have batteries that are more than capable of supporting this demanding performance. And now the relentless demand for technology has reached out and encompassed the electronic speed controller. Thus, we are faced with the difficult task of supporting these electron gulping monsters with their seemingly unlimited source of current, via a variable speed controller, capable of delivering up to 70 amps at 30 volts. This amounts to a total power dissipation of 2.1 kilowatts, all inside a flimsy model aircraft. Speed controller development Broadly speaking, speed controllers fall into two categories: forward speed only and reversible. The forward speed type is used mainly in. aircraft, track cars and electric boats. All of these applications place weight and voltage delivered to the motor above versatility. For applications where reversing the motor is a must, a reversing controller is used. These controllers feature a bridge output or a relay to effect the polarity change. Thus, they are heavier and usually more expensive than the forward only controllers. Typical applications are off-road buggies, model ships and most sports models where versatility and realism are th,e key points. The forward-only controller is often fitted with dynamic braking, a feature easily achieved in electric propulsion by simply placing a dead short across the motor terminals. As with all things, speed controllers had a fairly primitive beginning and a typical controller of the 1970s DECEMBER 1991 53 ,+5V + 33 GND~ 330k 10k D1 1S2473 -0.1 + 180k 7 SIGNAL IN 4 11 10k I + 2.7k IC1 BA607A .OSI 09 S1P +24V MAX ... 18k 47k-8.2k + 1+ .05 05 2SMi42 12 6 .05 MOTOR 10 D11 S1P ~ .01! .,. .05! This is the circuit of one of the most popular speed controllers of the late 1970s, made by Futaba. It used a relay for reversing, was rated at up to 10 amps & fitted into a case about the size of a cigarette pack. would deliver about 10 amps in a reversing controller and about 20 amps in a forward-only controller. Keep in .mind here that the motors they were required to drive were equally as primitive and typical current consumptions were in the order of 4-10 amps at 12V. The reversing controller usually used a relay to effect the reversal and these speed controllers were not small. Shown in one of the photos with this article is a finned unit made by Sunlux. This is a reversing 15/20A 12V device. One ofthe most popular speed controls of the late 1970s was the Futaba, giving a reversible 10 amps at 12V and again featuring a relay. About the size of a cigarette pack and built without a heatsink, it was a little prone to overheating when pushed near its limits but gave good service for many years when used with the more conventional motors. Here lies the key issue in speed control design: the ON resistance of 54 SILICON CHIP the switching semiconductors. At high currents, even a small resistance results in a significant voltage drop across the output stage. This lost voltage is critical in a racing application and is the key factor in deciding as to which unit you choose for your application. Luckily for us, the relentless quest for improved battery and magnet performance has been matched by the semiconductor manufacturers who have given us that magical little device known as a FET. However, even a very good FET such as the IRFZ44 has an ON resistance of around .025Q. Therefore, at 50 amps, the voltage drop will be about 1.25V, giving a power dissipation of 62.5W. This power is wasted as heat inside the model, heating the electronics and stressing the output stages. It would, of course, be better if it were delivered to the motor where it would provide extra propulsive force. Thus, we can draw several very significant conclusions immediately from this simple observation: (1) Nothing is better than a stout piece of wire for connecting the motor to the battery. (2) A relay is the next best thing for switching the motor ON and OFF. (3) If you must use semiconductors for switching, use those with the lowest ON resistance that you can buy and use plenty of them in parallel. This reduces the effective ON resistance and therefore reduces the total dissipation. It is quite common to see anything up to eight FETs in parallel in some commercial controllers. These units are very small and very expensive - as much as $350 each. The figures quoted for these modern commercial FET speed controllers are breathtaking, such as 250 amps sustained and 1000 amps instantaneous for forward only controllers. Reversing units are quoted at 150 amps sustained, with a peak instantaneous rating of 450 amps, while dynamic braking on the unidirectional models is quoted at 60 amps. Just how accurate these figures are, I cannot attest to, however I suspect they are fairly close to the mark. What's more, some It may be hard to believe but electric propulsion is being used for progressively larger and heavier models. This twin Partenavia P68 Victor, shown here in the construction stage, will be used as a test bed for an electronic speed controller currently under development by the author. of these units are quite small and most do not feature a heatsink - another technological marvel. Therefore, we now have our first design parameter for our proposed speed controller. The output stages will feature FETs - several of them in parallel. How many, what type and in what arrangement will not be resolved until we examine exactly what the modern electric motor demands of the proposed controller. High power cells and motors For those who have been away from R/C modelling, the world of electric propulsion is a complete revelation. Gone are the days of button cell nicads which melt down if too much curr.ent is pulled from them and which explode if too much current is pushed back into them. In their place stands a glittering array of batteries, some quite capable of melting down battery chargers or welding the connecting wires to the car chassis if one is not very careful. What we have now is a source of electrons of almost zero internal impedance, in case sizes which even as little as five years ago were just a dream. Electric flight is the main beneficiary of these advances, although most models benefit from weight reductions . . However, it is the motors themselves which stagger the imagination. Technology has invaded the world of electric motors in a big way and everything from new magnetic materials to class 10 bearings have been brought into play to squeeze out every last drop of performance. The result is a bewildering array of motors and accessories described in a language which is as mysterious as any ancient Middle Eastern dialect. What does it all mean? Well you might ask, and we will spend the remainder of this column and all of next month's to unravel the mysteries of electric motor language. Motor construction A typical model motor consists of three major sections: the motor can, which houses the front bearing and magnets; the armature and commutator; and the endbell containing the rear bearing and motor brushes. The motor cans are arranged in a hierarchical order, the classification of which seems to defy all but the most expert electric enthusiasts. On the face of it, there appear to be two popular classification systems, one American and one European, the most logical being the American system. The American motors range in size from 020 and 035 (which usually use 4-cell battery packs) to the 05, 075, 10, 15 , 25, 40 and, less usual, the 60. These numbers approximate the output power of an internal combustion motor expressed in cubic inches. The first surprise for tyro electric fan (if you will pardon the pun) is the size of the prop these motors swing and the speed at which they spin it. A 10 x 6-inch prop spinning at 13,000 RPM is really quite ordinary! Thus a 15 size electric motor delivers about the same output power as a 0.15 cubic inch glow plug motor. These figures are usually but not always based on 6-cell battery packs. The Japanese call the 05 housing the 540 series and these are remarkably similar in construction to the American motors. Armature winds range from 6-27 turns . The European system seems to be based on the armature winding and the can sizes seem to be confined to 3 7mm, 42mm and 45mm diameters. The length of the motor varies considerably in various models and the brush housings are quite different in construction from the American and Japanese systems. The Europeans offer armatures of various lengths and windings to accommodate the number of battery cells used in any particular application. Thus, armature winds range from 320 turns to accommodate 7-30 cells. They also use very large commutator areas for adequate brush cooling, a very big item in high power, high revving motors. This also contributes to armature length. Figures of up to 50,000 RPM can be achieved from some motors and brush/commutator heating becomes a serious problem. The magnets are the heart of the modern motor and the rare earth magnets have revolutionised this area of motor design. Low-cost motors are still available with the old ferrite magnets but some of the more exotic rare earth magnets such as samarium cobalt and neodymium are used extensively in the more expensive high-performance motors. Neodymium magnets are, however, prone to demagnetisation at high temperatures and suffer badly in some ii;istallations. A well-ventilated model aircraft is their best environment. Motors of this type are expensive and run at about $370-400. Compare this to a good, fun motor (Speed 600,075, 7-8 cell) at $21.95. And that's it for this month. Stand by for r..ext month's exciting developments. SC 0ECE/11BE R 1991 55 CIRCUIII' 'NOTEBOOK · Interesting circuit ideas which we have ch ecked but not built and tested. Contributions from readers are welcome and will be paid for at standard rates. Budget burglar alarm system Here's a low-cost burglar alarm system that's ideal for protecting garages and garden sheds. The circuit is based on a 555 timer (ICl) which is wired as a monostable. When power is applied via key-operated switch Sl, the two 47µF timing capacitors are initially held discharged by a transistor inside !Cl. During this time, ICl's pin 3 output is low and so the relay is off. When the normally-open reed switch contacts close (eg, when a door is opened), ICl's pin 2 trigger input is pulled low and the internal transistor turns off. !Cl thus switches its pin 3 output high and turns on the relay to activate the siren. At the same time , the 47µF timing S1 - - - - 4 - -ro SIREN OR HORN IC1 555 .01 6.8k ,--_ 56 SILICON CHIP 1k 03 1N4002 DZ) and the 6.8kQ resistor are not really necessary. These compon ents can all be deleted and the bottom leg of the lMQ trim pot connected directly to the timing capacitors. Also, the two 47µF timing capacitors can be replaced by a single lOOµF unit). Cameron Fraser, Mulgrave, Vic. ($15) capacitors charge via constant current source Ql and trim pot VRl. Wh en the voltage across the 47µ F capacitors reaches 2/3Vcc , the mon ostable resets , pin 3 switch es low again and the relay turns off. VRl allows the alarm time to be set as required . (Editor 's note : constan t cu rrent source Ql , its associated diodes (Dl & Expandable 3-way quiz game This 3-wayquizgameuses a 74LS75 quad D latch, a 555 timer and two 74LSZO dual 4-input NAND gates. It works like this: the in puts and thus the outputs of the four D-type flipflops are normally high and so the four LEDs are turned off. The output of the 555 timer is normally low and by combining this output with the four Q outputs of the flipflops via NAND gates ICla & IClb, the Enable inputs at pins 4 & 13 are controlled. Thus, when the Enable input is high (the normal condition in this circuit), the Q output of each flipflop will follow the associated data (D) input. When one of the four buttons is pressed, say Sl, the Dl line is pulled low, LED 1 lights and a low pulse is delivered from NAND gate ICZa to pin 2 of the 5~5 (IC4). IC4's output at pin 3 thus goes high. At the same time, when pin 16 ofIC3 goes low, it causes the output of IClb to go high. This causes the output of ICla to go low, which locks out the effect of any of the other buttons. ~ _,.._ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _....,__ _ +5V 1k 1k 1k 5 ...ll. 01 ...£. 02 ..E.. 6 03 7 IC3 74LS75 04 .,. .,. IC4 555 After about 2. 5 seconds, the 4.7µF capacitor at pin 6 of th e 555 charges to its threshold value an d the 555 output reverts to low and restores the Enable input on IC3 high. This resets the circuit and allows the game to be played again. The circuit has the advantage that it can be expanded by, for example, continued next page using a hex D latch and 6-input AND and NAND gates. (Editor's note: it seems likely that IC1b could be eliminated in this circuit by taking the three inputs to IC1a S1 a AO-O permanently high. This would mean that only one dual 4-input NAND gate would be necessary). Steven Merrifield, Newlyn, Vic. ($30) INPUT f1 250mA 240VAC &V + S1b NO--O Power supply for flash gun This simple circuit provides a 3V DC supply at 3A continuous to power photographic flash guns. It runs off the mains and so does away with need for batteries. The advantage of this scheme is that the colour temperature of the flash gun does not change, as it would as the battery condition deteriorates. The transformer is a 6-15V 2A type (available from most retailers), with the secondary connec·tion made to the 6V tap. BR1 is a 400V 6A bridge rectifier and this drives 2200µ F and 0.1µF capacitors to provide a smooth 9V DC 0-11 V voltmeter has LED indicators Built around three quad op amp ICs, this circuit uses LEDs to indicate voltage measurements from 0-11 V. There are 12 LEDs in all, each representing a voltage step of 1V (except for the bottom LED which represents 0.5V). As the circuit at right shows, the 12 op amps are all wired as comparators and these drive the LEDs via 8200 current limiting resistors. The noninverting (+) inputs of the comparators are all tied together and connected to the signal input terminal, while their inverting inputs are connected to a resistive divider string made up of 12 10kO resistors. Because there is a 1V drop across each resistor, IC4c is referenced to 0.1 100 + 16VW - 3.1V 3A CONTINUOUS input to an LM350 regulator. The LM350 is an adjustable 1.230V regulator rated at 3A. The 1800 and 1200 resistors set the regulator to provide 3.1 Vat its output, while the 100µF capacitor provides additional smoothing. The output can then be connected to the flash gun power input. Note that, in operation, the LM350 maintains 1.2Vbetween its OUT & ADJ terminals. The output voltage can thus be set to some other value using the formula: VouT = (120 + R)/96 where R is the value of the resistor between the ADJ terminal of the regulator and GND. Darren Yates, SILICON CHIP. +1V, IC4b to +2V and so on up to IC2a which is referenced to +11 V. IC4d is tied to 0V and thus switches its output high and lights LED 12 as soon as the signal input exceeds about 0.5V. The remaining op amps further up the chain then progressively switch their outputs high as the signal voltage applied to the input terminal is increased. Power for the circuit is derived from a 15V DC plugpack or battery supply which must be rated at 300mA. Diode D1 provides reverse polarity protection, while 3-terminal regulator ICl provides a regulated +12V rail for the op amps and the voltage divider. LED 13 and its associated 8200 current limiting resistor provide power on/ off indication. Paul Fitzgerald, Te Aroha, NZ. ($25) D1 1N4002 15V FROM PLUGPACK OR BATTERY ... The 12 op amps are all wired as comparatc;rs and these drive the LEDs via 820Q current limiting resistors. DECEMBER19 91 57 DIGITAL MULTI METER HC -4510 DISPLAV:41/2 DIGIT BASIC ACCURACY: 0.5% DC V DC VOLTAGE : 0-1000V DC CURRENT: 0-10A AC VOLTAGE : 0-750V AC CURRENT: 0-10A RESISTANCE: 0-20M OHMS CONTINUITY TEST, DIODE TEST DATA HOLD 20 MHz DUAL TRACE OSCILLOSCOPE N_O_W_$_12_9_._9_5_-_:::-..-..i.._..:_{_-I •0•1•3•0•3•0·.··.··.··.···.·R_R_P_S_1_4_9._9_s__ ~;=T~~s!it6~~~~~~;~;angular DIGITAL MULTI METER HC-5010EC • Deflection Factor: 5mV to 20V I Div on 12 r?nges in 1.2.5 step with fine control • Bandwidth DC: DC to 20 MHz (-3dB) AC: 10Hz to 20 MHz (·3dB) • Operat ing modes CH-A, CH-B, DUAL and ADD (ALTICHOP L202 only) • Chop Frequency: 200 KHz Approx . • Channel separation: Better than 60dB at 1KHz DISPLAY: 3 1/2 DIGIT BASIC ACCURACY: 0.5% DC DC VOLTAGE : 0-1000V DC CURRENT: 0-10A AC VOLTAGE : 0-750V AC CURRENT: 0-1 OA RESISTANCE : 0-20M OHMS CONTINUITY TEST, DIODE TEST s~~~ ~\\) O13010 ... ..... ............ RRP $119.95 NOW $99.95 DIGITAL MULTI METER HC-889 DISPLAY: 3 1/2 DIGIT DC VOLTAGE : 0-1000V DC CURRENT: 0-10A AC VOLTAGE : 0-750V RESISTANCE : 0-20M OHMS CONTINUITY TEST, DIODE TEST, DATA HOLD, TA HFE GAIN, AUTO RANGE DMM WITH BAR GRAPH _ __ _ __ _ _ NOW _ __ _ _ _.;;;::;_i:....~ O13040 ...._ .. .. _ ..... .._ ...... RRP $99.95 $89.95 TI ME BASE • Type: Automatic & normal triggered in automatic mode, sweep is obtai ned wit hout input signal • Sweep Time : 0.2m Sec to 0.5 Sec/ Div on ranges in 1-2-5 step with fi ne control and X-Y. • Magnifier: X5 at all times. TRIGGERING • Sensitivity lnt : 1 Div or more EX1: 1Vp-p or more. • Source : INT, CH·B, LINE or EXT • Triggering Level: Positive and Negetive, continuously var iable level; Pull for Auto. • Sync: AC, HF Rej, TV (each+ or-) at TV Sync. TV•H (line) and (frame) sync are switched automatically by SWEEP TIME/Div switch. HORIZONTAL DEFLECTION • Deflection factor: 5mV to 20VI Div on 12 ranges in 1·2•5 step with fine control • Frequency response: DC to MHz ( ·3dB) • Max Input Voltage: 300V DC+ AC Peak of 600V p-p • X-Y operation: X-Y mode is selected by SWEEP TIME/ Div switch. • Intensity Modulation Z Axis: TTL Level (3Vp-p-50V) + bright, - dark OTHER SPECS:. Weight: 7Kg Approx • Dimens ions: 162 (H) x 2941W) x 352(D)mm. 0 12105.......................... RRP $750 NOW $695 DIGITAL MULTI METER HC-3500T DISPLAY:3/12 DIGIT BASIC ACCURACY: 0.5% DC DC VOLTAGE : 0-1000V DC CURRENT: 0-20A AC VOLTAGE0-750V AC CURRENT 0-20A RESISTANCE: 0-20M .OHMS TEMPERATURE:-20C -1200C CONTINUITY TEST, DIODE TEST TEMPERATURE CAPACITANCE FREQUENCY, hie TEST, DATA HOLD. O13000 ........ ......... .. RRP $169.95 NOW $149.95 ANALOGUE/DIGITAL MULTIMETER HC-5050DB 3 1/2 DIGIT ·BASIC ACCURACY: 0,5% DC DC VOLTAGE: 0-1000V DC CURRENT: 0-10A. AC VOLTAGE : 0-750V AC CURRENT: 0-1 0A RESISTANCE : 0-20M OHMS DC AC RMS: -45d8 -+50d8 TEMPERATURE: -20C-1200C AC FREQ SPREAD: 50Hz-2KHz CONTINUITY TEST, DIODE TEST O13020 ... ....... ... ..... RRP $169.95 NOW $149.95 LOGIC PROBE (LP-2800) USEFUL FOR TTL AND CMOS . HIGH & LOW INDICATORS PULSE MEMORY. FOR THE HOBBIEST OR SERIOUS TECHNIICIAN FOR TRAC ING THOSE HARD TO FIND FAULTS ON LOGIC BOARDS. O11272 ............ ................ RRP$29.95 NOW $19.95 100 MHz 3 CHANNEL 8 TRACE MODEL 5510 This instrument meets the customers needs in quality of performa nce, effi cie ncy, function, design, and cost! Being rugged, highly reliable and a multi-purpose 3 channel, 8 trace oscilloscope with a 6 inch domed mesh type 14kV post deflection acceleration cathode.ray tube and with a fine red internal grati cule. FEATURES: • Compactness, lightweight, ruggedness and simple design. • The diecast frame provides compactnes§ lightweight and rugged ness. • Easy Operation Light torque lever switches and push button switches are used. • High Brightness CTR, high acceleration voltage and high beam eff iciency of th e 150mm rectangular CTR ensures a bright high speedsweep observati on • Multi mode display system CH1. CH2, CH3, Add any combination or alfthe cha nnels may be viewed simultaniously. Maximum 8 trace displaying is possible with the ALT sweep fu nction. • High sensitivity and wide frequency bandwidth . The maximum vertical sensit ivity is 1 mVIDIV (when x 5 MAG)at 20 MHz or greater 3dB and mVIDIV at 100 MHz or greater -3dB. • High input impendance The input impendance of CH1, CH2, CH3, is 1Mnt2%, 25pF t3pF O121 09 ......... RRP $2995.00 NOW $1,995 SCHOOLS & COLLEGES TAKE NOTE! ONLV$1,695tax exempt. LEDS ~I== ~I== QUALITY 3mm LEDS 1·9 1-9 10--99 100+ """' ~ ,..~ 10-99 100+ Z10140(R) $0.15 Z101 41(G).. $0.20 Z101 43(Y) .. $0.20 Z101 45(0) .. $0.20 $0.1 2 $0.18 $0.18 $0.18 $0.10 $0.15 $0.15 $0.1 5 QUA LITY 5mm LEDS BNC PA NEL SOC KET 1-9 10+ 100+ P1 0516 $2.50 $2.25 $ 1.50 -----=== Z10150(R). $0.15 $0.12 $0.10 Z1 0151 (G). $0.25 $0.20 $0.18 Z101 52(Y) .. $0.25 $0.20 $0.18 FLASHI NG LEDS BNC CRI MP PLUG 1-9 10-99 100+ P1 0530 $3.95 $3.7 5 $3.00 BNC SOLDER LESS TWI ST ON PLUG CANNON PLUGS AND SOCKETS RED 5mm 1-9 10+ Z10159 $1 .10 $1.00 Designed to transm it at 40kHz (L 19990) & recieve at 40k Hz (L1 9991 ) withup to 20V 1/P on the transmitter. These units :• can•t be heard so are ··· ideal for TV remo te dec tectors & information carriers as they can be either pulsed or used in a conti nu ous wave mode. Transmitter 1-9 10+ L19990...... .$2.95 $1.95 Receiver L19991 ....... $2.95 $1.95 1-9 10+ 100+ 1 se 12e 1Se 12e 1 se 12e 1se 12e DUDEI only ) I THIS MONTHS TOP TEN GAME SPECIALS! dectectors, burglar alarms, motion -- ARWSO ---------, ME' I l7~~~-~-._ . _____::·~~ controls, water level RECTANG ULAR LEDS RED 20<: GREE N 20<: YELLOW 20<: ORANGE 2oe r.------- • ' 15p,A(E #4. I THEIR FINEST HOUR ............................ $59.95 SEARCH FOR THE KING ..................... . $59.95 LINKS CHALLENGE GOLF. .................. $59.95 ELVIRA ................................................... $69.95 JET SET PACK ...................................... $59.95 KINGS QUEST FIVE .................. ............ $69.95 SECRET OF MONKEY ISLAND ............ $59.95 HEART OF CHINA ...................... ........... $69.95 RED BARON ......... ............................... .. $69.9 5 TEST DRIVE ll ........................................ $69.95 2 WAY................ $59.95 4 WAY................ $69.95 MON ITOR & KEYBOARD SWITCH BOXES only $69.50 ·.·: (...,_N _I_C_A_D_s_ ~ Save a fo rtune on expe nsive thr ow away batteries with these q ual ity Nica ds and Recha rgersl IDC PLUGS & SOCKETS WOW! FR OM $1.00 Size AA 450mA.H 1-9 10+ $2.95 $2. 75 100+ $ 2.50 Si ze C 1 2 A H $9.95 $9. 50 Sl,a D 1 2 AH $9.95 $9.50 IC SOCKETS D TYPE IDC PLUGS 1-9 10+ • DE9P Bpl n plug CANNON TYPE 3 PIN CHASSIS MALE 1-9 10-99 CANNON TYPE 3 PIN LINE FEMALE 1·9 1()..99 100+ P10964 $3.95 $3.50 $2.90 ~ LOW PROFILE IC SOCKETS , 0B25 P 25 pi n p lu g •• P12170 $4.50 $3.95 $3.50 Save a sma ll fortune on th ese " Direct Import" low profile IC sockets ! PCB mounting s olde r ta ll. All tin plated phosp hor bronze or barry llium and dual w ipe 10-88 100 + P10966 $4.95 $4.50 $3. 50 DB25 CONNECTOR SPECIALS 1-9 P10880 DE9P P10885 DE9S P10891 DA15S P10892 DA 15C P10895 DA15S P10902 DB25C P10904 DB25P P10905 DB25S $1.00 $0.80 $1.00 $0.70 $1.00 $0.70 $1.00 $0.90 $1.00 $0.80 $1.00 $0.80 $1.00 $0.80 $1.00 $0.80 P10550 s pin 15e 12e 1oe P105so 14pin 20e 1se 15e P10565 16pin 20e 1se 16e P10567 1Spin 30e 25e 22e P10568 20pi n 35e 30e 25e P10569 22pin 35e 30e 26e P1os 10 24pin 3Se 3Qe 26e P 10512 2Spin 4 5e 35e 30e P1os15 40pin 45e 40e 35e 1-9 ECONOMY TRANSFORMER 10-99 1-9 100+ WIRE WRAP IC SOCKETS These qua li ty 3 level wire COMPUTER CABLES • Si x conductor ahlelded · computer lnlerface ca ble. W12670 • CIC6 6 con. 1-BM 10M+ 100M+ $1 .30M $ 1.10M $ 1.00M W12672 • CIC9 9 con. 1-9 M 10M+ 1O0M+ $1.60M $ 1.50M $1.20M W12674 • CIC12 12 con. wrap socket s are ti n p lated pho sphor b ronze. P10579 Spin P10580 14pin P10585 16pin P10587 18pin P10590 20pin P10592 22 pin P10594 24pin P10596 28pin P10598 40pin $1. 50 $1.40 $ 1.85 $1. 70 $1.95 $1.80 $1.95 $1.80 $2.95 $2.75 $2. 95 $2.70 $3.95 $3.50 $3.95 $3.50 $4.95 $4.50 ~ 2SJ49 2SJ56 2SK134 2SK176 10+ • Plug P12200 $3.95 $3.00 • Socket P12201 $3.95 $3.00 6672 240V 15 30vc 1A tapped M16672 ........$12.95 $11.95 l:\:·:·: -:c-.,..,,,,,,...,.,.,,.,,.,,..--.,. L FANS =_) :::::.'.::::~.-----------==~':,::. VOLTAGE REGULATORS BARGAINS Descri ption 1-9 10+ 7805UC 7812UC 7815 UC 7905UC 7912UC 79 15 UC 78L05 78L12 $0.50 $0.50 $0.60 $0.45 $0.45 $0.45 $0.55 $0.60 $0.60 $0.40 $0.40 $0.55 $0. 55 $0.30 $0.30 $0.50 10+ 2155 240V 6-15V 1A M12155 .. ..... $8.95 $7.95 2156 240V 6-15V A2 M12156 ........ $13.95 $12.95 2851 240V 12•6V CT 250mA .... $4.95 .. $4.50 CANNON TYPE 3 PIN LINE MALE 1-9 We have a great ran ge of panel mete rs at g real pricesl 010500 MU45 0•1mA $9.95 010502 MU45 5()150uA $9.95 010504 MU45 0·1 00UA $9.95 010533 MU52E 0·5.JA $12.95 010538 MU65 0·50uA $1 2.95 0 10540 MU65 0-1mA $12.95 0 10550 MU650-100uA$12.95 010560 MU650-20V $12.95 MOSFET SPECIALS 1-9 P10960 $4.50 $3.50 $2.50 10 ♦ DTYPE IDCSOCKETS for rellablllty. 1-9 10+ 100+ CANNON TYPE 3 PIN CHASSIS FEMALE . 1-9 P12166 $1.50 $1.20 $1 .00 • DA15P 15pln plu g P12168 $ 1.50 $1.20 $1.00 100+ P10962 $3.50 $2.95 $2.50 100+ LM324 $1.00 $0.90 555 741 $0.40 $0.50 $0.38 $0.45 C 12V DC FANS 80 x 80 x 25.4mm 12V DC. 1.7 Watt 0.14 Amp T12469 ................ $18.95 10+ fans, only $17.Q5 FANS Quality fans for use In power amps, computer hotspot coollng etc. Anywhoro you nood plenty of air. 240V 4 5/8" T12461 ..$16.95 115V 4 5/8" T12463 .. $16.95 240V 31/2" T12465 .. $16.95 115V 3112" T12467 .. $16.95 10+ tana (mixed) Only $14.95. $9.50 $10.00 $8.50 $9.50 O+ $8.00 $9.50 $8.00 $8.90 TOGGLE SWITCHES $8.95 HEATSINK COMPOUND ~ Heatsink compo und ·i• applied to the base a nd moun ti ng studs of transistors & d iodes. It : maintains a positi ve : he atsink seal that im proves hea t transfer from the d evice to the heatsink, thu s increasing overall e ffici e ncy. : H11 800 .. 109 ... $2.00 : H11810.1 50g. $29.95 In the past there have been a number of designs for battery operated and mains operated lasers but this is the first design using a visible laser diode. Using this device, a small PC board and three AA-size cells, you can make a very effective laser pointer. By LEO SIMPSON Every year, laser diodes are produced in quantities which run into the millions. They are used in CD and video disc players, CD ROM drives and laser printers. The vast majority of these laser diodes produce their output in the infrared region, at around 780 nanometres. The laser diode used in this project is normally intended for use in bar code readers, as used in supermarkets and libraries. It produces its output as red light, at around 670 nanometres. The laser diode is, of course, a spe60 SILICON CHIP cial type of light emitting diode. And since light emitting diodes do not normally produce a very narrow beam, the laser diode is fitted with a collimator lens assembly which also doubles as a heatsink. The laser diode assembly is mounted on a small PC board together with its drive circuitry which is a constant current source. The PC board and AA batteries can then be packaged in a short length of electrical conduit to make a handy laser pointer. This can be used at lectures and slide shows and has the advantage of being a little more bulky than commercial units which are more expensive. Since when is bulk an advantage? It makes the unit easier to point more precisely and the larger size means that it is less likely to be misplaced. Besides being used as a laser pointer, the unit could also be used for a range of optical experiments, including data transmission. It could even possibly be used as the basis for a surveyor's level, although higher power gas lasers are usually used in this last application. The circuit Now let's talk about the circuit which is shown in Fig. l. The laser diode is connected to the battery supply via a constant current source comprising transistors Q1 and QZ and diode Dl. The battery supply is shown as having of range of3.5-5V. It could be supplied from three 1.5V AA alkaline cells or four 1.2V nickel S1 +3.5-5VC>------e _ _ _ _...__....__ _ _____,....__ _ ....__-o 22ll ~· 100 B2n 3.9pf OLLIMATING LENS LOOSEN SET SCREW ANO SLIDE TO ADJUST SET 60-100mA 01 2N2219A E GND<:r---il>----------------u LASER POINTER VIEWED FROM BELOW cadmium rechargeable cells. You might expect that a laser diode circuit would be little more than a battery and a resistor since it is essentially just a light emitting diode. However, the operating current is a good deal higher than for typical LEDs. Whereas LEDs typically operate with a current of 10 milliamps (depending on their application), a laser diode usually requires somewhere between 60 and 100 milliamps. This means that a current limiting resistor is impractical and a constant current source is required. The circuit works as follows. Q1 and D1 work together to provide a constant voltage of close to 1.2V between Q1 's collector and emitter. This voltage will remain constant for quite large variations of the bat- Fig.1 (left): the circuit uses Ql & Q2 as a constant current source so that the laser diode is never overdriven. Fig.2 (above) shows the laser diode assembly. tery supply voltage. The voltage from the collector of Q1 is applied directly to the base of Q2 which functions as an emitter follower. This means that the voltage at the emitter of Q2 will be constant at around 0.6 volts. Because the voltage at the emitter ofQ2 is constant and because its emitter load resistor is fixed, it follows that the emitter and collector currents of Q2 are constant. Hence, the laser diode current, supplied from the collector ofQ2, is constant. Trimpot VR1 is used to set the current to about 80mA. We'll talk about this setting later in the article. Note that there are two diodes inside the laser diode 3-lead package. The laser diode itself is between pins 1 & 2 while another diode, a photodetector diode, is connected between The Laser Pointer is powered by three AA cells installed in a 4-cell holder (one battery position is shorted out). Keep the parts leads as short as possible. pins 2 & 3. This is shown with a lOOQ resistor connected across it although in this circuit it is superfluous. Its real purpose is to monitor the light output of the laser diode and to use the voltage signal to control a feedback loop which ensures that the laser light level is constant over a long period of time. This is important if the laser diode is used with optical fibres or barcode scanners, or in other data transmission applications. Construction The Laser Pointer circuit is assembled onto a small PC board measuring 85 x 26mm. The laser diode and the collimating lens assembly are supplied separately and need to be assembled together. The first step is to short all three leads of the laser diode together to avoid the possibility of damage to it via static discharges. The assembly is as shown in Fig.2. Remove the end plate by undoing the two screws, taking care not to lose the two spring washers (not shown in Fig.2). This done, insert the laser diode and reassemble the unit. While it is possible to do so, we do not recommend that you try to adjust the collimating lens - it is not an easy job and the unit comes preset anyway. Now that you have finished the laser diode assembly, put it aside and proceed to assemble the PC board. Do not install the laser diode on the circuit board until it has been powered up and the trim pot set for the correct current. If you connect the laser diode into circuit before you are sure it is working properly, you could easily DECEMBER 1991 61 Fig.3: install the parts on the PC board as shown here. Note that pin 2 of the laser diode is connected to the metal case & thus to the collimating lens assembly. The entire assembly slides into a conduit housing as shown at right. damage the dio de - a very costly exercise. No special order needs to be followed in assembling the board. Just install the com ponents as shown while making sure that their values are correct and that the transistors and electrolytic capacitors are correctly oriented. Check your work carefully When you have finished assembling all the components onto the board (with the exception of the laser diode). You now need a source of 4.5V DC or thereabouts. You can use a DC pow er supply or the battery pack. If the latter, you will need to wire it up. If you intend using alkaline cells (wh ich put out a nominal 1.5V), you will need to wire the 4-cell holder so that one cell PARTS LIST 1 Toshiba ROLD9200 red laser diode 1 collimating lens assembly to suit laser 1 PC board, 85 x 25mm 2 2N2219A NPN transistors (Q1,Q2) 1 1 N4148 signal diode (D1) 1 SPST pushbutton momentar·y contact switch (S1) 1 4-cell AA battery holder and snap connector 2 100µF 16VW electrolytic capacitors 1 3.9pF ceramic disc capacitor 1 100 trimpot (VR1) Resistors (0.25W, 5%) 1 1kQ 1 100Q 1 82Q 1 22Q 2 10Q 1 1Q Miscellaneous Electrical conduit for laser housing , foam rubber, insu lated hookup wire, black spray paint , laser warning label, solder. 62 SILICON CH IP position is shorted out. Once this has been done, insert the three cells and measure the output voltage across the snap connector. It should be about 4.5V. Connect the supply to the board and short the collector of Q 2 to the +4.5V rail. Now connect a digital multimeter across the lQ resistor and adjust trim pot VRl for a reading of 85mV. This corresponds to a constant current of 85 milliamps. Now you are ready to connect the laser into circuit. Mount the laser assembly onto the PC board and secure it with the supplied screws and spring washers. Solder short leads to pins 1 & 3 of the laser dio de and sleeve them to avoid shorts to pin 2, then solder the two leads to the PC board. Now apply power and the laser diode should, but may not necessarily, put out laser light. If the current through the laser diode is not quite high enough , it will emit red light in a focused beam but it will not be laser light because the energy input is insufficient. If this is the case , you will have to change the setting of VRl to increase the current through Q2. To do this, reconnect your digital multimeter across the l Q resistor and rotate VRl so th e reading increases. By the time the reading is 90m V, corresponding to a laser diode current of 90mA, the light should have that characteristic "speckle" appearance of laser light. Do not , under any circumstances, increase the laser current beyond lO0mA, otherwise there is a strong chance that you will damage the laser diode. Having confirmed that the laser diode is able to "lase", you can finish the assembly. The laser housing is made from a couple of lengths of 40mm OD electrical conduit joined together with a short length of 40mm ID conduit. One end of the resulting tube assembly is blocked off with a disc of wood or plastic while the other end has a similar disc with a 6mm hole drilled in it for the laser light output. The photos show how the tube assembly goes together. The battery pack is mounted in one half of the tube assembly, together with a piece of foam rubber packed in so that it does not slide about. Similarly, the laser PC board assembly goes in the other half, again with a piece of foam rubber so that it does not rattle about. Finally, a momentary contact pushbutton switch (Sl) is mounted in the laser tube assembly to function as the ON switch. It is simply wired in series with the positive lead from the battery pack. SC Where to buy the kit The complete kit for this project, including laser diode, collimating lens & laser warning label , is available from Oatley Electronics for $179 plus $6 for certified postage and packing. Oatley Electronics can also supply infrared laser diodes and gas laser tubes. Their address is PO Box 89, Oatley, 2223. Phone (02) 579 4985. Note : copyright of the PC board associated with this project is retained by Oatley Electronics. A high quality military n!t!~eu~~1tb1i\fe:~~~I~ spectrum from medium and high powered incadescent spotlights and flood lights. Its pyrexglass base makes it capable of withstanding high temperatures. 3 ~i~~i~:"a~ttlm~ ~~~ Can be used in conjunction with infra red night viewers and IA respon• sive CCD cameras. Many colour video cameras and most monochrome video cameras have good IR response. Check by ~~e~2~ These precision glass prism assemblies are in excellent condition and were originally used to form a periscope in a tank navigation system. Their original price would have been around $1000! The two glass prisms can be removed from their holding assemblies. Make a high quality periscope or use in optical systems. A must for persons interested in high quality optics: 5 19 For the two prisms Illustrated •~rr:.:~~J ~~~:a control. Excellent for night surveillance equipment! We have a limited quantity of these. brand new filters at a FRACTION OF THEIR REAL PRICE: ONLY: $69 For the more serious applications we have some brand new, large 4mW and 10mW tubes. Both the tubes are of exceptional quality and would normally cost about three times the price indicated. Call us for a special deal for a tube and supply combination. The ridiculous tube only prices are: 4mW. 10mW We have a limited stock of laser heads with an output of 0.5mW-1mW and their special mains operated power supplies. Both of these are professional quality brand new components, and to put them into action you will simply have them enclose the laser and the supply in a small box, and connect them to a mains supply via a fuse. LIMITED QUANTITY AT THE CLEARANCE PRICE OF: s175 .. s155 $386 12V SOLENOIDS Used and tested high quality 12V solenoids. Suits 100's of electromechanical applications. The plunger is strong enough to be used as door latch. Very powerful, has a return spring and a travel of approximately 10mm. ONLY: s15 EA. Not a complete kit, but just the absolute essentials: An unmarked 6032 IR tube, or a fibre optic tube with some blemishes, and a very compact power supply based on a military inverter. You get the tube, the power supply components, a circuit and basic instructions. A very compact viewer can be made by using these basic components. Excellent value! Call to check availability. 5 174 If you could never afford the fascination of owning a gas laser, have a close look at the " trio", in th is " SPECIAL LASER INTRODUClDRY OFFER". The tubes are used . but have plenty of life left in them. They are GUARANTEED! You get one small tube with an output of around 1mW, one high quality low divergence SIEMENS laser head with an output at about 3mW, and one of our reliable and efficient 12V UNIVERSAL LASER POWER SUPPLY KITS. A tube and the supply will easily slide into inexpensive 50mm SWV pipe, which makes for a compact sell powered laser head. Casing is not supplied. Several of our customers reported that AT NIGHT, THE BEAM FROM THE SIEMENS W/o.S VISIBLE UP TO 4km AWAY! The kit comes with full instructions and it even includes a prewound transformer. The unlimited applications include laser pointers, surveying, optical experiments, medical field, holography, and fascinating laser displays. JUST IN TIME FOR THE FESTIVE SEASON. For a limited time onl~ we are offering this Experimenters delight! A brand new SmW 780nM820nM infra red laser diodes supplied with a collimating lens, heatsink, laser diode data, a suitable driver circuit and the components for this circuit. Visible in low light. Excellent for IR sights, data links, high quality audio links, security perimeter protection, laset listening devices, etc. s59 For all the above components I We provide a circuit for a laser listening system which relies on window vibrations, produced by sounds in a room. Works at good distances! The whole kit may be available when this magazine is published. Best give us a call. s149 "TmO~~OA~~~~fN (~fc~EOF ~hat~ mbre a spec,afChristmas offer: FREE CERTIFIED PACK AND POST ON THIS TRIO! The free P&P offer applies till the end of 1991. Don't require the bigger tube? The remaining "Duo" can be bought for $991 A complete mains filter employing two inductors and three capacitors fitted in a metal shielded IEC socket. We include a 4G joule varistor with each filter! ON SPECIAL AT sa.90 EA. or 10 for $65 1SkV EHT POWER SUPPLY Used but guaranteed regulated supply. Needs a DC supply of 19-28V for full 15kV S00uA output. That's about 7.SW of EHT energy! Great for all sorts of experimentation. Will work with reduced input voltage as low as 3V but output is reduced in voltage and current capacity. s45 ~ A very small complete kit • Includes both an adjustable lens and an eyepiece • The matching tubes, lenses and eyepieces were removed from new German night vision equipment • Simple construction: Instructions provided • For a limited time only the kit is supplied with a high quality military inverter: Draws only 25mA from the 9V battery• IR illumination is required in the dark, and good ranges are possible with just medium powered focussable torches, fitted with an IR filter • You would normally pay over $3000 for a view like this! DON'T MISS OUT! Hobbyists delight! One of these panels will fully . charge a 6V500mA HR .. nicad battery pack in about 4 hours! You can also connect as many of these panels in series or parallel to produce the voltage and current required. DIMENSIONS: 200mm X 200mm Voc: BV (max) 10V lsc: 250mA (max) 300mA Order Solar Panel: SP1 ONLY s14 $3 P&P Based on a "state of the art" 3mW visible re laser diode, and a matching heatsi nk/collimator assembly. The circuit even has provision for digital switching. Use them for pointers, sights, communications, security, etc. This kit includes the laser diode, collimator, PCB and components, and all the casing: Everything you need to· make a complete pointer! PRICE IS REDUCED BY OVER 20%' $179 + $5 Cert P&P A small 3mW 670nM visible laser diode head. Just connect it to a battery via a switch. Produces a well collimated beam. You could pay three times our price for a laser pointer or gun sight that uses a similar head. s199 Melbourne Distributor: Electronics World (03) 723 3860 or (03) 723 3094 Closed from 24/12/91 till 14/1/92: Gone fishing! s329 ONLY E.A. Oct. 1991 Includes the IA tube, lens eyepiece, electronics kit and the case kit: KIT No. IANWS. 75mm round IA plast ic filter: $16. DECEMBER1991 63 COMPUTER BITS BY JENNIFER BONNITCHA Windows 3 & the dreaded UAE Ever got the dreaded Unrecoverable Application Error (DAE) message while working in Windows? There are several reasons why this pesky bug sometimes appears. Most of the time, you can start Windows applications by simply double clicking on the required icon. However, you can also load an application as an icon instead of running it by holding down the <Shift> key and double clicking on the required icon. Even DOS programs like WordPerfect can use this technique. The program's icon sits quietly at the bottom of the screen, waiting for your next instruction. Saving changes When you exit the Program Manager, you are given the opportunity to save any changes made to the layout of the Program Manager. Occasionally, the changes made may need to be saved, however exiting Windows to save changes and then restarting is then either double click or click on Switch to; (4). Select the File menu then choose Exit Windows; (5). Click OK to save the changes. A dialog box called COMMAND now displays. Its message tells you an Application is still active; to complete the operation, exit the application then try closing Windows; (6). Select OK and the FROGMAN.IN! file will be updated and Windows will still be active. If you are not running Windows in 386 Enhanced Mode, you don't have the opportunity to run your DOS programs in a window. You can, however, switch back and forth between Windows and Non-Windows applications by pressing the <Ctrl Esc> combination to activate the Task List. "The majority of UAEs can be traced to configuration problems. These include disc caches, Terminate and Stay Resident (TSR) programs loaded before Windows, some font managers, and older 286 & 386 computers (usually clones) unable to run Windows successfully". time consuming. When you exit Windows, the PROGRAM.IN! file is saved; you can force Windows to save any changes but not exit the program by following these steps: (1). Double Click on the DOS icon; (2). Press <Ctrl Esc> to activate the Task List; (3). Choose the Program Manager 64 SILICON CHIP Choose the program you require and hey presto, multi- tasking. The UAE - what to do Windows comes complete with an equivalent to the helpful DOS message: "Bad command or file name". The "UNRECOVERABLE APPLICATION ERROR - Terminating Current Appli- cation" message is just as meaningful. Its general meaning is that an application has intruded on the area of RAM set aside for another application, thus corrupting the area. The "best" solution is to reboot your computer and start again - hopefully you save your work regularly and this won't cause too much anguish. Working towards a UAE-free world, Windows 3 .1 is supposed to include parameter validation designed to made Windows more robust and so help eliminate the dreaded bug. Possible causes So what causes the UAE in the first place? There are several possibilities, including: (1). Running the incorrect version of DOS on your computer. Windows requires DOS 3.1 or higher; (2). Using a version of an application designed for earlier versions of Windows. (3). Selecting the wrong machine or network during setup. (4). Using memory-resident software incompatible with Windows. (5) Plain bad luck. While the above seems to cover a fair amount of ground, the plain truth is that it's usually just one of those things. It's not necessarily the application itself that causes the problem; the message simply tells you that there has been a RAM collision, rather than which application was at fault. The majority of UAEs can be traced to configuration problems, according the Microsoft technical support. These include disc caches, Terminate and Stay Resident (TSR) programs loaded before Windows, some font managers, and older 286 and 386 computers (usually clones) unable to run Windows successfully. Remem- Application Compatibility Warning The application you are about to run, EXCEL.EXE, was designed for a previous version of Windows. (l) You should obtain an updated version of the application that is compatible with Windows 3.0. To run the current version of the application, choose Cancel. Then, exit Windows, restart it by typing Win /r, and start the application again. If you choose OK and continue to start this application, you might encounter compatibility problems that could cause the application or Windows to terminate unexpectedly. OK This "Application Compatibility Warning" message is displayed if you try to load a version of Excel that was designed for an earlier version of Windows. If you choose OK, an Unexpected Application Error message appears & this eventually causes both the application & Windows to terminate. ber that Windows operates in different ways, depending on your computer. If you have a 386 or 486 machine, Windows can run several applications at the same time - DOS or Windows. 286 machines, on the other hand, run in standard mode where one program only is active, although other programs can be loaded but inactive. With all this happening at the same time, Windows needs to make sure one program's RAM requirements don't conflict with any others. Although this is not an especially difficult task, sometimes programs are not as well-behaved as they could be, thus the UAE problems. Not all UAEs cause severe problems. While the message indicates that the application will terminate, you can often click OK, then close the application in an orderly manner. The suggestion is that memory has been corrupted, so you are well advised to heed the message, close the application and reboot. , Should you choose to continue, the initial UAE could cause other applications to crash with UAE messages, even though they are not actually the cause of the problem. Remember that the UAE doesn't apportion blame; it just tells it how it is. There is also the possibility of data corruption, so to be on the safe side, choose the "Save As" option and give the data file another name. A voiding UAEs While Microsoft acknowledges the UAE problem, Windows 3.1 hopefully will see the end of this annoying pest. Tracking the source of the problem is difficult if you get them right from the start, but not impossible. Normally, Setup examines your hardware and displays the components you are using in the Windows Setup window. Some computers and networks are not detected correctly by the Setup program. Some machines from several manufacturers, including NEC, NCR, Toshiba and all HewlettPackard, must be specifically selected in Windows setup. If you select incorrectly, Windows will not work correctly. You can exit Windows and run the DOS version of Setup from the WINDOWS directory, this time choosing the correct hardware. Sometimes an unusual hardware configuration can leave your system hanging. Should you experience this problem, run Setup using the /I switch; ie, type SETUP/I at the DOS prompt to prevent Setup from doing any hardware detection. Windows requires DOS 3 .1 or higher to function correctly. DOS 5's new features include advanced memory management, an enhanced graphic shell, disc partitions to 2Gb, a full-screen editor, command history utility and a new version of the Smartdrive disc cache. A nice feature of DOS 5 is its ability to check your current DOS version then install itself with all the special features your computer requires. Your computer's BIOS may not be compatible with Windows. It is a relatively simple matter to upgrade the BIOS chip if you have a "brand name" computer; clones could be more difficult to upgrade. Windows supplies drivers for the most commonly used display adaptors and network cards - but some inevitably miss out and you could be the unlucky owner. If you are having problems, remove all the driver software then re-install them one at a time, noting the result. This may indeed be tedious, but it is better than continual UAEs. Hopefully you will find the culprit, then you can check whether the supplier has a later version, suitable for Windows 3. Microsoft's Supplemental Driver Library could also be of assistance if Windows doesn't have a particular driver. Sometimes even Windows applications cause UAEs. Excel has a nasty habit of creating UAEs when too many (how many is too many?) features are added to a chart embedded in a worksheet - but not always! The UAE is often preceded by a low/out of memory message and will also appear if you have other applications active (like Solitaire!). Solution? - same as all the rest. Save the worksheet/chart, etc using File Save As, then exit Windows and reboot. The main culprit is RAM collision, so even if you think the UAE has passed on by, reboot. Microsoft also has available the Microsoft Windows Resource Kit which contains detailed information on solving unrecoverable application errors. Finally, an interesting book from Brian Livingston (IDG Books) called Windows 3 Secrets reveals many undocumented "features", workarounds and bugs of Windows 3. Some are just, well , "gee that's cute", while others can improve Windows' performance quite markedly. The book also includes two discs with shareware and public domain software covering virus detection, communications programs, various utilities and, of course, the inevitable games. SC DECEMBER1991 65 IEEE488 adapter card for PCs This adapter card connects a PC to peripherals using the IEEE488 standard. The software included with the card enables it to talk to, and listen to, device(s) connected to the interface, as well as take control of them. The software is supported by BASICA and the functions of the routines are fully documented. Examples are given in the manual to help with set-up but there is very little information given about practical applications. The IEEE488 adapter retails for $395. For further information, contact Electronic Solutions, 2/5 Waltham St, Artarmon, NSW. Phone (02) 906 6666. New hard drives from HP Hewlett Packard has just released a family of SCSl~2 drives ranging from 422Mb to 1 .355Gb for integration into the Macintosh Quadra 900 to provide additional mass storage for data intensive applications. One full-height or two half-height high performance drives can be placed inside the unit. They are intended for use in desktop publishing and computer aided design and manufacturing (CAD/CAM). The 3.5-inch drive offers a formatted capacity of 422Mb with an aver- 66 SILICON CHIP age seek time of 12.6 milliseconds. The larger 5.25-inch drives come in sizes of 1 .355Gb, 1.07Gb and 677Mb formatted capacity and have a seek time of 13.5 milliseconds. All drives in the range have a maximum transfer rate of 1 .5Mb/s. Prices vary from $4,975 for the 3.5inch drive to $9,490 for the 1.35Gb 5.25-inch drive (ex tax). For more information, contact Dene Maddren at Hewlett Packard Australia, 31-41 Joseph St, Blackburn 3130. Phone (03) 272 2651. Sound blaster card for gamesmanship The Sound Blaster could be described as all you could ever want in a sound card. It has a complete 11voice synthesiser that is Adlib compatible, a voice input (sampling) channel to record your own samples, and a full MIDI interface. Backed up with a host of software, it is an extremely powerful sound tool. The software synthesiser allows you to learn and play orchestral pieces with one finger. Accompaniments are added automatically. The MIDI input ailows the synthesiser to be triggered from an external MIDI device. The MIDI port is designed into a joystick, thus eliminating the need for a separate joystick card. To use the MIDI port however, an additional connector box and cables are required. A speech synthesiser is included that has a psychiatrist, called Dr Sbaitso, to analyse your problems. It will also take a text file and convert it to speech. Other software items include a talking parrot and a collection of voice development tools. The input has a built-in preamp to allow either microphone or line inputs to be used. Its OMA technology and hardware proprietary compression algorithm enhance performance by reducing the amount of storage needed for each sample. The output can be fed to an inbuilt stereo amplifier or to an external hifi system. A large collection of software is already available and games being released now have device drivers that support Sound Blaster architecture. The card retails for $299 and is available from all Dick Smith Electronics stores. Eprom programmer for PCs This programmer is ideal for field use as it connects to the parallel port of any PC. It can program any EPROM or FLASH memory to a capacity of 1Mb. It automatically detects the type of chip in its ZIF socket using the identifier code now used by most manufacturers. Chips that don't have the code can safely be programmed by selecting the appropriate algorithm on the screen. The software is menu-driven and different parallel ports may be selected. Defaults may be changed and saved to disc for quicker programming if small production runs are to be made. Several utility programs are included that support format changes, create check sums, and allow binary file splitting. Software is available on either 3.5inch or 5.25-inch diskette and the unit retails for $300 plus sales tax. Contact Edwin Schoell at JED Microprocessors, 5-7 Chandler Rd, Boronia 3155. Phone (03) 762 3588. 4-megabit RAM in vertical package Texas Instruments has announced the availability of a new 4-megabit · RAM in a new vertical mount package which will allow computer manufacturers to squeeze 32 megabytes of RAM (64 packages mounted upright) onto an area the size of a credit ca,rd. The new package, called VPAK , is extremely thin and is su rface mountable. It will supplied in 4Mb x 1 or 1Mb x 4 organisation. Engineering samples will be available in the first quarter of 1992 and full production will be in the second quarter of 1992. For further information , contact Rita Wong , Texas Instruments, PO Box 106, North Ryde , NSW 2113. Phone (02) 878 9000. Intelligent printer buffer/sharer Compaq's new 33MHz 486 portable Compaq has just released its new 33MHz 486 portable, the first using Th in Film Transistor (TFT) active matrix technology. This technology, combined with a hot cathode back-lit panel, enables the VGA display to provide hig h contrast, fast response (less than 50ms) and a selection of over 4000 colours. In 640 x 480 resolution, up to 256 colours may be used simultaneously. The display also includes an adjustable viewing angle to reduce glare and provide optimal image quality. The Advanced Video Graphics System also supports simultaneous internal and external monitor displays. Two models are available. Each comes with 4Mb of RAM as standard, expandable to 32Mb. Also included are a 3.5-inch high-density floppy disc drive, a detachable full -sized keyboard and two 32-bit EISA expansion slots. These allow the addition of high performance graphics cards, modems and LAN cards . The model 120 comes with a 120Mb fixed drive and retails for $19,594, whereas the model 210 includes a 210Mb fixed drive and retail s for $21,274. Both prices include sales tax. Paper feeders for laser printers If you have people in your office sharing a laser printer over a network, you will realize the problems involved when the . printer is fed from two or more paper bins. There is a dramatic red uction in productivity if the operation is subject to the constant delay and disruption ' caused by having to change th e paper supply. The Ergofeeder can hold up · to six paper bins and an envelope bin. Paper can be fed to the printer from any one of them with a keystroke at the operator's terminal. The bins can be loaded with letterheads, continuation sheets, paper for office copies or any other combination . This way you can print your first page on letterhead, other pages on continuation sheets and the file copies on A4 paper. The envelope can also be printed without the hassle of manual feeding. The Ergofeeder fits all leading models and is claimed to increase laser printing productivity by up to 50%. For more information, contact Greg Ducquet at Practical Peripherals, Level 11, 231 North Quay, Brisbane 4000. Phone (07) 236 1373. Lightweight monitor has touch-screen option Th is unit allows up to four computers to share two printers. It is microprocessor controlled and comes with 512Kb of memory, expandable to 1Mb. The buffer receives the incoming data and stores it until the selected printer is ready. Data routing and function controls are selected via a combination of front panel switches and key-i n software codes. Function controls include time-outs for data files and form feeds, with one option allowing up to 100 copies to be made from the same file. The Bafo Intelligent Buffer Switch retails for $549 from Electronic Solutions, 2/5 Waltham St, Artarmon , NSW. Phone (02) 906 6666. Planar International has just released the ELT320 terminal, featuring DEC VT320 compatibility and crisp, flicker-free images. It provides a resolution of 640 by 400 pixels (picture elements) and an exceptionally wide viewing angle. The monitor measures and weighs about 1/10th that of con ventional CRT screens and, with its plug-in compatibility and UNIX protocol standards, can be connected to existing host computers. These terminals are ideal for limited space environmerits :md also have the option of a touch screen feature. For further information, contact Amtex Electronics, 13 Avon Rd, North Ryde, NSW 2113. Phone (02) 805 0844. 0ECEM BEH199 1 67 Build a colour TV pattern generator, Pt.2 This month, we describe construction of our new colour TV pattern generator. This is made easy since most of the components are on a single PC board and there is only one setting up adjustment. By JOHN CLARKE The Colour TV Pattern Generator is housed in a standard plastic instrument cas e measuring 205 x 158 x 62mm. All of the space on the floor of the case is taken up by a large singlesided PC board measuring 17 5 x 142mm and coded SC02210911. It has quite a few wire links on it but we opted for this arrangement because a double-sided board would have been 68 SILICON CHIP considerably more expensive. There are two toggle switches, one rotary switch and a LED on the front panel, while the rear panel carries a power input socket (for an external 12VAC plugpack), a direct video output socket (RCA type) and the RF output from the modulator (also an RCA socket). There are two types of modulator recommended for this project. One mounts directly onto the PC board while the other, a slightly larger model, is ,trapped onto the rear panel and linked to the PC board with short wires. More on these later. You can begin construction by carefully checking the PC board pattern against the artwork published in this article. Check for shorted, open circuit or missing tracks. Ensuring that the p.attern is free from errors at this stage can save a lot of time and frustration later on. Now test the PC board for correct fit inside the case. It should easily fit on the floor of the case, with the mounting holes lining up with the integral plastic standoffs. Make sure that these mounting holes are large enough to accept the self-tapping screws sup- HOLE FOR MODULATOR OUTPUT ORFOUTPUT VIDEO MODULATOR VM41'6/A2E3 GND S3 ~ S1 ~ REAR PANEL PC stakes and links The first step in the construction is to install PC stakes at the 14 external wiring points (see Fig.4). Make sure you heat the pins well with your soldering iron before tinning them with the solder. If you are not careful with this step, it is quite easy to end up with dry joints on the PC stakes. Next to go in are the wire links and there are quite a few of these, all using tinned copper wire (in our case, 0.71mm in diameter). Before cutting the links to length, it is a good idea to straighten the wire. This can be done by clamping one end of the wire in a ---::f':) LED1 13,.-- A FRONT PANEL Fig.4. use this diagram in conjunction with the circuit diagram published last month when assembling the pattern generator. Note that the HC CMOS ICs are easily damaged by static electricity, so be sure to observe the precautions described in the text. plied and check that the modulator mounting holes in the PC board are large enough to accept the mounting pins. K 14 vice and then pulling the other end with a pair of pliers until the wire stretches slightly. Make sure that all the links are dead straight and parallel, to avoid short circuits. Next, install the resistors and diodes. Be careful with the orientation of the diodes and check that the correct type is installed at each position. There are three types of diodes used in the circuit. The black diodes with the silver stripe on one end are the rectifier types used for D1-D4. Diodes D5-D9 are small signal diodes which are clear-bodied with orange internals. The final diode is ZDl, a zener diode. Watch out for static The !Cs can now be installed but take care with static discharges when you are installing the CMOS devices. If the weather is very dry and your room is carpeted, it is highly likely that you will have a problem with static discharges. This can certainly blow !Cs in this circuit (we blew a couple ourselves). The way to avoid this problem is to earth the barrel of your soldering iron and then conn ect it via a jumper lead to the OV pattern on the PC board. After that , you need to earth yourself. Use a wrist strap (or a jumper lead connected to your metal watch band) to connect yourself to the OV pattern on the PC board. Finally, avoid touching the pins of the !Cs when mounting them on the board and solder their supply pins first. The capacitors, trimmer capacitor VCl and the crystals can now be installed. Note that the electrolytic capacitors must be correctly oriented, as shown on the overlay diagram . Also, be sure to · use the correct crystal at DHY .\ /ll/•:/l 1991 69 ,_ ___ \ ,_----'--- - This version of the pattern generator uses the VM416/A2E3 modulator which is mounted directly on the PC board. Take care with the wiring to the pattern selector switch, as it's easy to make a mistake here. each location on the board. The board assembly can now be completed by installing the two 3terminal regulators and transistor Ql. Note that REGl is a 7812 device while REG2 is a 7805. Two modulator types As noted above, there are two recommended video modulators for the Colour TV Pattern Generator. The first is the VM416/ A2E3 which mounts directly onto the PC board and is available from Dick Smith Electronics. The second typ e is the HL-RM-TS3/4AU which mounts on the rear panel and is available from Jaycar Electronics. If you are using the VM416/ A2E3 modulator, solder its mounting lugs to the copper pads on the PC board using a heavy-duty soldering iron. The remaining two leads from the modu70 SILICON CI-IIP lator solder into the PC board to make the INPUT and V+ connections. If you are using the HL-RM-TS3/ 4AU modulator, insert 100mm lengths of insulated hookup wire into the GND, INPUT and V+ locations on the PC board for connection to the modulator later on. Drilling the panels Work can now begin on the case. You will need to drill holes in the front and rear panels to accommodate the switches and sockets. The Dynamark label can be used as a template for marking the drilling positions on the front panel. After the holes have been drilled and deburred, the label can be stuck to the front panel and the holes cut through it with a sharp utility knife. The rear panel requires holes for the power input socket, the RCA video output socket and a large hole for the video modulator output socket. If the HL-RM-TS3/4AU modulator is used, it should be mounted upside down in the top corner of the rear panel, as shown in the photographs. Drill holes for the RCA output socket and for a ca:)le tie to clamp it to the rear panel. Alternatively, the hole position for the on-board VM416/A2E3 modulator can be found by temporarily positioning the rear panel and the PC board in the case. Drill a small pilot hole initially, then ream the hole out to clear an RCA plug. Installation & wiring Once all the holes have been drilled, mount the various hardware items on the panels, then install the panels and the PC board in the case. Fig.4 shows the wiring details. Use various colours of hookup wire or rainbow cable for the wiring to the LED and switches. By using different col- BUILD YOUR OWN FAX/MODEM This is a fully featured kit The Comma Fax/Modem is a commercially designed kit you can build. It will turn your PC (or Macintosh) into both a fax machine which can transmit faxes up to 9600 baud, as well as a Modem which su pports both 1200 and 2400 baud. You get all the necessary components as well as a professional case, and power supply. You also receive FREE Fax/Modem software. All this for less than $300. The Comma Fax/Modem uses the latest technology in digit al signal processing to ensure lasting troublefree operation. Send faxes from home The Comma Fax/Modem is a fully featured fax machine similar to units 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 them first. Programs supported such as Ventura Publisher, Wordperfect, Windows, TIFF and Dr Halo to name but a few. You can view incoming faxes on-screen or print them using a st andard 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 expensiv:e fax paper. Time saving The Comma Fax/Modem will also receive faxes in background while you continue to work. When faxing out the Fax/Modem will redial an engaged number so you can 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 of regularly used fax numbers for easy retrieval As well it's also a modem The Comma Fax/Modem is a fully AT command series V compatible modem. Features include V22/V22bis standards (V21/23 is an option) both 1200 and 2400 baud rates are supported as well as auto answer, dialing and disconnect. You will find it compatible with all popular communication services including most bulletin boards. Available soon MMP and V42bis option. FREE Software With each kit you will receive the QL2 Fax/Modem software featuring both pull-down menus and mouse support. Value packed kit Each kit h as 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-by-step guide to testing your Fax/Modem throughout the building process. ONLY $299.00 Note: This device does not have an Austel permit in force. Connection to Telecom lines is an offence. We also srock a range of motherboards, external disk drives, hard disk drives, add-on interface cards, as well as a huge range of cables, adaprors, switch boxes and chips. Call roday for very competitive pricing. Cheap 3.5" Floppy Disk Drives We have available a LIMITED quantity of external FDD, 1.44MB. Ideal for computer hackers. These drives have high quality Japanese Citizen Disk Drives. External case has a lead fitted with a Centronics 36 pin connector. Normally we would sell this unit for $329.00ea. This month only or until stocks are sold $99.00ea. Even as spare parts they are worth more than the asking price. ASK FOR A COPY OF OUR FREE CATALOGUE DEALER ENQUIRIES WELCOME Motherboard $100 Savings Month Give your XT or 286 computer a holiday this year wnh on of these motherboard upgrades. All motherboards come wnh 1MB of RAM. 286-1 2wnh 1MBof RAM $299.00 Save$100 286 - 16 wnh 1MB of RAM $325.00 Save $100 386SX- 16wnh 1MBof RAM $499.00 Save$100 386SX - 25 wnh 1MB of RAM $650.00 Save $100 386 - 33 Cache wnh 1 MB of RAM $999.00 Save $100 Speak to the experts about your motherboard upgrade TRY PC MARKETPLACE SUPERFAST MAILORDER - PHONE OR FAX TODAY! pfii{(jfeesons PC MARKETPLACE Pty Ltd FREIGHT CHARGES Include $1o whh order for all normal hems. Heavy hems e.g. monhors add $15. 14 day money back guarantee. PHONE (02) 418 6711 FAX (02)4186713 Mail Order Address: Order by phone (use credit card), by fax or by mall. Unless Insurance Is declined It will be charged at P.O. Box 1100 Lane Cove 1% of total purchase. This is for your protection. NSW2066 PRICES CURRENT FOR MONTH OF PUBLICATION OR WHILE STOCKS LAST e SERVICE IS THE DIFFERENCE e [Z] [BI SERVICE IS THE DIFFERENCE e SERVICE IS THE DIFFERENCE e SERVICE IS THE DIFFERENCE shorts and incorrectly placed or oriented components. Assuming that you get the correct reading, check that the output of REG 1 is somewhere between +11.4V and +12 .6V. Once again, switch off immediately if you find anything amiss. Now you can check that power is being applied to all the ICs. There should be +5V on the positive supply pin of every IC, except for IC16 which operates at +lZV. Finding the positive supply pin for all the 74HC series ICs is easy since it is always the highest numbered pin. Of the remaining two ICs, IC14 should have +5V on pin 8 while IC16 should have +lZV on pin 11. The alternative HL-RM-TS3/4AU modulator is mounted upside down on the rear panel and secured using a plastic cable tie. Its various terminals are then connected to the PC board using short lengths of hookup wire. ours, you will be able to easily identify each lead when it comes to checking the wiring later on. Be sure to use medium-duty hookup wire for the power switch (Sl) wiring. Finally, if you are using the HLRM-TS3/ 4AU modulator, the terminal closest to the rear panel connects to the INPUT (composite video) terminal on the PC board. The next terminal connects to the V+ terminal on the PC board, while the GND wire from the PC board is soldered to the case of the modulator. The remaining two inputs on this modulator are left unconnected. Cut the wires to these inputs short so that they are unable to contact the modulator case. If everything checks out, the pattern generator can now be checked on a TV set. To do this, connect a lead between the video modulator output and the RF input to your TV set and either tune to channel 2 for the VM416/ AZE3 modulator or to channel 4 for the HL-RM-TS3/4AUmodulator. Now Testing The pattern generator is now ready for testing. Plug the 12V AC plugpack lead into the power socket and set your multimeter to read 0-Z0V DC. Connect the negative lead of the multimeter to the metal case of the modulator and the positive lead to the output of the +5V regulator (REG 2). Apply power and check that the voltage reading on the multimeter is between +4.75V and +5.25V. If not, switch off immediately and check the PC board for faults such as solder CAPACITOR CODES 0 0 0 0 0 0 0 0 0 Value IEC Code EIA Code 0.1µF .01µF 330pF 220pF 100pF 82pF 33pF 5.6pF 100n 10n 330p 220p 100p 82p 33p 3p3 104 103 331 221 101 82 33 3.3 RESISTOR COLOUR CODES 0 0 0 0 0 0 0 0 0 0 0 0 72 No. Value 4-Band Code 5-Band Code 1 1 9 10MQ 36kQ 10kQ 5.6kQ 2.2kQ 1kQ 910Q 470Q 390Q 330Q 100Q brown black blue gold not applicable brown black orange gold green blue red gold red red red gold brown black red gold not applicable yellow purple brown gold orange white brown gold orange orange brown gold brown black brown gold brown black black green brown orange blue black red brown brown black black red brown green blue black brown brown red red blpck brown brown brown black black brown brown white brown black black brown yellow purple black black brown orange white black black brown orange orange black black brown brown black black black brown 1 3 1 1 2 SILICO N CHIP CI-118A 20MHz Dual Trace Osc;l.ll◄~ SPECIFICATIONS: Operating modes Yl, Y2, Yl and Y2 added are switchable alternately and lnterml ttently. Bandwidth, MHz: ■ DC coupled input: at -3dB .. 0-20 ■ DC coupled input: at -6dB .. 0-35 ■ AC coupled input: at -3dB .. 3x10·'-20 ■ AC coupled input: at -6dB .. 2x10·'-35 ■ input with external divider in position 1:1 .. 0-7.0 Transient response built-up time, ns, max.: ■ ■ DC coupled input: .. 17.5 with external divider in position 1:1 .. 50 Deflection factor (11 calibrated steps with 1-2-5 seq.) ■ ■ ■ mV /DIV: Accuracy,%: Max. input (AC/DC) V: .. 5-10' .. +/ - 4 .. 250 Input Impedance, Mohm/pf: ■ ■ ■ DC coupled input: with external divider in position 1:10 with external divider In position 1:1 .. 1/20 .. 10/15 .. 1/100 Sweep speed (21 calibrated steps with 1-2-5 seq.) ■ ■ ■ ns/ DIV: Accuracy,%: 50ns/ DIV+ Accuracy, %: 20ns/ DIV .. 20-50x10' .. +/- 4 .. +/ - 8 Trigger modes: ■ Autq, turning to triggered upon application of trigger signals HOPM (NORM). Trigger source: ■ Dimensions: 212 x 133 x 336mm Screen Size: 4" Includes 2 x 1:1 10:1 probes, and screen protection cover. Internal (from channe l Yl or Y2), external. Sensitivity for Internal s"9nchronlzation, V: ■ ■ 50Hz to 4MHz, DIV., Max.: .. 0.8 4MHz to 20MHz, DIV, Max.: .. 2 Sensitivity for external synchronization, V, Max.: ■ lOHz to 20MHz .. 0.2 Typical external synchroniz ation ■ Input imp. kohm/pf A.C.N . 001-372-372 .. 70 / 15 Note: for Go vernment Dept's, Schools, Sales Tax No. holders, etc only $430.43 ea. (ex-tax) - official order must be produced + DOT HATCH CHECK......____\ I / WHITE COLOUR RED / + - BARS------,GREYSCALE + POWER - =IIJI/JIIPCOLOUR TV PATTERN GENERATOR PATTERN Fig.5: this is the full size artwork for the front panel. fine-tune the TV set until the pattern selected is displayed on the screen. At this stage, colour may not be present because the colour burst frequency may need tweaking. Select the red raster pattern and adjust VC1 so that the screen is red. If you are using a metal-tipped alignment tool (better than a small screwdriver), you will need to remove it from VC1 after each adjustment to allow the crystal to oscillate correctly. The final setting for VC1 should be midway between the two positions where the colour drops out. This group of composite video waveforms is presented for those needing to troubleshoot the pattern generator. Below left is the colour bar signal while to its right is the equivalent grey scale signal. The waveforms on the facing page show the crosshatch signal (left) and the white raster signal (far right). 74 SILICON CHIP That completes the assembly. If all the patterns can be displayed on the screen, then your work is finished and you have a very useful service instrument for your workshop . Troubleshooting If it doesn't work, first check for incorrect wiring or component placeThe colour burst frequency is adjusted ment. The underside of the PC board by tweaking trimmer capacitor VC1 should also be checked for shorted until a red raster appears (see text). tracks, dry joints and open circuits. Make sure your wiring to the pattern selector switch is correct, as it is fairly kit projects do not usually malfunceasy to make a mistake here. . tion, the HC CMOS ICs specified in this If these checks do not find the probcircuit are more fragile than ordinary lem, then you will probably need acCMOS ICs . As pointed out earlier, they cess to an oscilloscope to check the are easily damaged by static electricwaveforms. Fig.1 in the November ity. If you are prodding about in the 1991 issue shows the main waveforms circuit, remember to wear a wrist strap. generated by each circuit block. Don't write off an IC before you By checking the waveforms at varihave thoroughly checked the solder ous points in the circuit, it shoul d be connections to its pins. Poor solderpossible to isolate the section which ing to IC pins and incorrectly wired is not functioning correctly. switches are the most common probNote that while the ICs supplied in lems in malfunctioning kits. r. ~~ ..-----n...._ . ~.~~ ~r Finally, there are two changes to the parts list and circuit from last month. First, the video modulator can be either a VM416/A2E3 or a HL-RM- ~~ TS3/4AU. Second, the 680Q resistor shown on the circuit (Fig.3) in series with the 6.8V zener diode (ZDl) should be changed to lOOQ. SC Fig.6: here is the full size artwork for the PC board. Check your board carefully against this pattern & repair any defects before mounting any of th e parts. DECEMBER1991 75 The Story of Electrical Energy, Pt.16 .Recent advances in thermal power station design include Pressurised Fluidised Bed Combustion, or PFBC systems. This new type of boiler, together with improved turbo alternator sets, increases the overall efficiency while decreasing costs. By BRYAN MAHER Thermal power stations have grown in capacity and improved in efficiency during their evolution over the past century. Yet boilers designed from about 1970 to the present are now regarded by some engineers as physically bigger, less efficient and more cumbersome than necessary, and thus too expensive. The designs we have seen previously in this series first pulverise the coal to a fine powder. This is then blown into a fire chamber lined with water/steam pipes. The flue gases then must be scrubbed and filtered to remove fly ash, sulphur dioxide, oxides of nitrogen and other pollutants. These scrubbers and filters have to be designed for the expected type of coal. That presents big problems. Australian power stations are sited close to coal mines, so the fuel properties for each station are well defined and the boilers are designed to suit. Things are different in many other countries. Some or all of the coal burned in Norway, Sweden, England, Japan, Peru and other countries must be imported. Changing world economics leads to a mixed variety of coals arriving at some power stations. For example, since 1984, up to 4% of all the coal burned in English power stations comes from foreign countries. In Japan, the figure is close to 100%. It would be a great help if boilers could accommodate a wide range of coals with a varying content of ash, sulphur, tar, gas and impurities. This is where the PFBC boiler comes in. PFBC boiler A radically new power station concept emerged from experiments during the 1970s, culminating in the building of a 15 megawatt test facility by Asea/ ABB at Malmo, Sweden in 1984. This consisted of a Pressurised Fluidised Bed Combustion (PFBC) boiler, as shown in the diagram of Fig.1. Coal in the form of 5mm particles is first mixed with dolomite (to add calcium) and then injected into the bottom of the fire chamber. When sufficient air is blown in from below, the mass of particles (coal, dolomite and ash) will be loosened up. At sufficient air velocities, all particles lose contact with their neighbours and float like a fluid in the airstream. This suspension is called a fluidised bed (the idea comes from coal gasification plants in the 1920s ). The vessel baseplate has a large This photo shows the huge size of a modern double-flow low pressure steam turbine. The largest blades are just over one metre long and the whole assembly is just on four metres in diameter and weighs close to 50 tonnes. 76 SILICON CHIP You can now afford a sate IIite TV system STACK 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 This is about 1/3 the price of corn parable systems Here's what you get: ~ A 1.8 metre pressed steel prime focus dish antenna, complete with all the mounting hardware - as well as a self supporting ground stand. 1J+ One super low noise LNB (low noise block converter) 1.4dB or better. w+ One KU band feedhorn and all the mounting hardware as well as a magnetic signal polariser. ltt 30 metres oflow loss coaxial cable with a single pair control line. ASH STORAGE 11+ A 99 channel infrared control satellite receiver with adjustable IF and audio bandwidth, polarity, and dual digital readout . The IR control unit has a range of approx. 10 metres. Before you receive your system the unit is pre-programmed to the popular AUSSAT transponders via the internal EEPROM memory. This unit is also suitable for C band applications. Fig.1: this diagram shows the principal components in a PFBC (pressurised fluidised bed combustion) demonstration power station built in Malmo, Sweden in 1984. The entire boiler furnace is housed in a pressurised container and the flue gases are used to drive a gas turbine. CALL, FAX or WRITE to AV-COMM PTY LTD. PO BOX 386, NORTHBRIDGE NSW 2063 PHONE (02) 949 7417 number of air nozzles. In operation, the fluidised bed can be four metres deep, consisting of about 1 % coal and 99% inert ash and dolomite. The ignition of the coal particles floating in the air stream raises the bed temperature to 850°C. Steam, generated in water pipes buried in the bed, is returned to a vertical pressure drum. From this, steam flows in more pipes laid in the furnace, returning to the drum in a superheated condition. Output steam from the boiler is at lOMPa (1500psi) and a temperature of 530°C. In the 15MW test facility, coal was fed in at 0.58kg/s to form a fluidised bed weighing 3.6 tonnes. Flue gas was produced at a rate of 8.1kg per second. First commercial unit The first commercial unit was rated at 206MW and was built for the Vartan CHP plant, and is similar to a 200MW unit installed for the American Electric Power Company (AEP) in 1990. In all its power stations, AEP burns 40 million tonnes of high sulphur content coal annually, mined in Ohio and Indiana. This new Pressurised Fluidised Bed Combustion technology was chosen for an upgrade of AEP's Tidd power plant at Brilliant, Ohio. FAX (02) 949 7095 All items are available seperately. Ask about our low noise "•c· band LNB, and other interesting products. All systems are provided with dish pointing details. ----------- 1 Yes Garry, I Please send me more information I on your l{ band satellite systems. I II Name ..................................... .. II I Address ................................... I I ................................................... I I ........................... P/Code., ........ I I I :Ce~~~~~::a . . . . . ... . . . . . . .~;;~~ 11. _ _ _ _ _ as ____ _ DECEMBER 1991 _.1 77 10 20 30 40 in 1990 by Asea Babcock, a consortium of the US companies ABB Carbon and Babcock Wilcox. Phase 2 of the Ohio clean coal program helps the funding of a 330MW PFBC unit being installed at AEP's Philip Sporn power-plant at New Haven, West Virginia. This unit, replacing two older 150MW boilers, will be in operation by 1995. 50m Pressure sphere COAL FIRED BOILER WITH DRY SCRUBBER PULVERISED COAL FIRED BOILER WITH REGENERATIVE AIR PREHEATING LIME ELECTRO S02 PREPARATION STATIC - REACTOR PRECIPITATOR FABRIC FILTER FLUE STACK GAS FAN PRESSURISED FLUIDISED BED BOILER PRESSURISED FLUIDISED GAS TURBINE BED Fig.2: here's how the size of the boiler and ancillary equipment for a conventional pulverised coal power station (top) compares with a PFBC station (above). Note that not only is the PFBC system smaller but it does not need separate precipitators or S0 2 reactors, leading to considerable cost savings. Fig.3 (below): a modern steam turboset made by ABB, Sweden. This has a single flow high pressure turbine (1), a double flow intermediate pressure turbine (2), and two double flow low pressure turbines (3 & 4). 78 SILICON CHIP The Tidd power plant is a working demonstration power station funded partly by the US Department of Energy and the Ohio State Coal Department's clean technology programs. The PFBC system at Tidd was installed But there's much more to the story. As Fig.1 shows, the complete combustor is enclosed within a cylindrical or spherical pressure vessel. The feed air is forced into the fluid ised bed until the pressure above the bed is 1680kPa (255psi). The products of combustion are forced out into multiple sets of 3-stage passive cyclones. Here the finest bed particles, caught up in the draught, are extracted from the flue gases. By controlling the fuel flow, the bed temperature can be maintained between 800°C and 900°C. The depth of the fluidised bed is regulated by the removal of ash from the bottom or by re-injecting stored ash. The deep bed and low fluidisation rate in the PFBC system assure a long contact time between bed and gas, yielding a very high combustion efficiency of 99%. This is about 3% better than conventional plants using pulverised coal. Fig.2 shows the greatly reduced size of a PFBC boiler installation compared to a conventional boiler of the same AIR PRESSURScD fLUIDScD 8!:0 BOILER CLEANED FLUE GAS TUHHtNf CONDENSE!l COAL ANO DOLOMITE !NTEfi-. COOLER 51 M\N power capacity. In both drawings, the auxiliaries required to clean the flue gases to government requirements are shown. Low sulphur emission Notice that the PFBC boiler does not need any electrostatic precipitator for fly ash removal, as these particles are caught by the internal cyclones. Nor is a sulphur dioxide (SO 2 ) reactor required. This is a big bonus, as many high quality coals (ie, those having energy ratings above 24 gigajoules per tonne) have a high sulphur content. In older types ofboilers, sulphur dioxide (SO 2 ) is produced in copious quantities by the burning of the fuel. This toxic gas, ifreleased into the atmosphere, reacts with airborne water vapour to produce sulphurous acid. This leads to acid rain and the resultant ruination ofrivers, fish, lakes, crops, trees and so on. Hence, huge SO 2 reactors are normally installed in power station flue lines to remove this gas. So bad was the problem in Europe that, in June 1988, the environmental ministers of the European Community agreed on a directive: chemical reactors were to be installed despite the huge cost; and sulphur dioxide was to be progressively reduced in existing plants by 20% in 1993, by 40% by 1998, and by 60% by the year 2003. Coal also contains ammonium compounds as impurities. These break down in the high furnace temperatures of conventional boilers to form nitrogen oxides. These may constitute as much as 500ppm (parts per million) of the flue gases. As well as being toxic, these gases also attack many common metals. Furthermore, if released ihto the atmosphere, they react with water vapour to form nitric and nitrous acids. Severe acid rain can result unless catalytic denoxing equipment is included in the power station flues. Photochemical smog can also result because of the absorption by nitrogen dioxide of ultraviolet light, releasing an oxygen radical which in turn reacts with the air and forms ozone. This oxidises hydrocarbons in the atmosphere to form photochemi- Fig.4: diagram of a proposed 332 megawatt power station in which the power will be extracted from both a steam turbine and a gas turbine. The net efficiency of this arrangement is expected to be close to 42%, a very worthwhile improvement over present day power stations. cal smog which is dangerous to human eyes and lungs. Benefits of PFBC stations A most interesting benefit of the fluidised bed technology is that over 93% of the sulphur dioxide is removed within the furnace by reaction with the dolomite added in with the coal. The end product is a dry gypsum solid, which has a ready market. Thus,'desulphurisation takes place in the fluidised bed and no SO 2 reactors are needed in the outside flue line. This easily meets Swedish standards which limit sulphur dioxide emissions to 100mg of SO 2 per megajoule of energy rating of the power station. Furthermore, the comparatively low DECEMBER1991 79 condenser. The exhaust from the gas turbine heats the feedwater in the economiser before these flue gases vent up the stack. Steam generated by the PFBC boiler will drive a modern 4-stage turbine set as shown in Fig.3. In this turboset, superheated steam first drives the high pressure (HP) turbine and is reheated before passing to the intermediate pressure (IP) turbine. Steam enters the middle of the IP stage and exhausts from both ends. To generate yet more shaft power, the IP exhaust steam drives two (not one) double-flow low-pressure (LP) turbines. These LP units are huge, having individual blades as long as 1050mm in the final stage. Each LP turbine bladeset rotor is approximately four metres in diameter and 10 metres long. So large are these final blades that the centrifugal force on them when they are rotating results in tensile stresses of 200-300 tonnes. They must not only be very securely anchored to the hub but blade resonances must be minimised if vibration stresses are not to become excessive. Efficiency enhancements This photo shows a PFBC boiler before it is enclosed in its spherical pressure vessel. This boiler is intended for a 200MW turboalternator set. temperature and high pressure in a fluidised bed furnace result in extremely small quantities of oxides of nitrogen being formed in the first place. So no denoxing plant is needed. The cost saving of the above is enormous. Currently, two billion pounds is being spent in England on equipment to reduce sulphur and nitrogen emissions from a handful of large existing power stations with a total output of 12 gigawatts. Because a PFBC power station automatically deals with pollutants , these stations can successfully burn almost any type of coal. This fact can lead to cost savings of a high order. If the coal contains more sulphur, the operators simply add slightly more dolomite. No problem! The almost complete combustion of the coal (99%) also results in considerable savings. Over the life of a large power station, this can amount to tens of millions of dollars. Furthermore, as the diagram ofFig.2 indicates, the PFBC system, being 80 SILICON CHIP smaller for the same power, represents large capital savings. Compared to a conventional pulverised coal burning plant, the PFBC steam generator is 70% smaller and uses 65% less steel for its construction. Finally, because of the lower combustion temperature, the ash is not softened. This fact eliminates the problem of high temperature corrosion within the plant and allows easy collection of fly ash in the passive cyclones. Commercial PFBC station The proposed commercial PFBC power station shown in Fig.4 contains even more innovations aimed at increased efficiency. The flue gases from the cyclones are so clean that they can be used to directly power a 3-stage gas turbine. This turbine drives both the boiler air compressor and a 74MW alternator. For economy, the air compressor interstage cooler is cooled by the feedwater returning from the turbine Any loss of steam pressure due to path friction represents a power loss. Therefore, in modern LP turbines, baffle plates are intentionally dispensed with to allow unimpeded passage of steam to the exhaust and prevent premature flow separation in the diffuser. The exhaust steam casing is also designed with a minimum of stiffeners and braces, as these would increase the pressure loss by friction. As a result of all these improvements, the overall efficiency of a complete large PFBC power station can be as high as 41. 5 % corn pared to a figure of 38.5% for a conventional station of similar size. If a 3% improvement does not sound much, consider that it represents 30MW in a lGW power station. That's a lot of extra power, provided at no extra expense. SC Acknowledgement Grateful thanks to ABB/ASEA Review and Action and National Power, England for data and photographs. BOOKSHELF Anti-viral book for computers • JOf)Olhcr\l.11.".a\lO Computer Computer Viruses, by Jonathan L. Mayo. 2nd printing, 1989 by Windcrest Books, Blue Ridge Summit, Philadelphia, USA. Soft covers, 188 x 232mm, 160 pages. Anti-virus disc included. ISBN 0 8306 3382 0. $49.95. Computer Viruses by Jonathan Mayo is a comprehensive look at what viruses are and how they work. In the first chapter, an historical account is given on the more infamous viruses, along with actual examples of their capabilities. He classes viruses into different categories, depending on the Everyday Electronics Data Book Everyday Electronics Data Book, by Mike Tooley. Published 1990 by PC Publishing, Kent, UK. Soft covers, 140 x 216mm, 250 pages. ISBN 1 870775 02 3. $19.95. The Everyday Electronics Data Book explains the concepts, principles and techniques which have everyday relevance in the world of electronics. It is not really a book that would teach you electronics but a quick reference guide that is useful for looking up terms that you might not be sure of, or for finding out what a certain rating means. The text is brief and to the point. Text and data tables are generously interspersed with examples, tips and havoc they create. These include logic bombs, Trojan horses, worms and viruses. The second and third chapters deal with how viruses get into systems, where they hide and how to look for them. The anti-viral programs and utilities currently available are reviewed and a brief description on how they work is also given. This could be thought of as a first-aid kit for your computer, should it 'catch' something. But the book emphasises that prevention is better than cure and includes a chapter on virus-proofing your computer. At the back is a user's guide to the anti-viral utility disc that comes with the book. This is full of "vaccines", "flu shots" and remedies for treating a sick PC. The book retails for $49.95 and is available from all Dick Smith Electronics stores (Cat B-6052). (M.C.) Semiconductor substitution guide Semicondu~tor General-Purpose Replacements (6th edition). Published 1986 by Howard W. Sams & Co, Indianapolis, Indiana. Soft covers, hints that will help with avoiding some of the problems and pitfalls that would otherwise be "put down to experience". The first sections cover circuit laws , preferred values, codes, markings and passive components. Networks, attenuators and filters are analysed and formulas are given for applications. The sections on active components include theory of operation, explanations of operating parameters, relevant formulas and hints as to design considerations. Circuits make up the rest of the book, with sections covering transistor amplifiers, oscillators, timers, power supplies and operational amplifiers (op amps). The design considerations are given for each circuit as 218 x 280mm, 418 pages. ISBN 0 672 22540 1. $34.95. What can you say about semiconductor replacement guides? Not much except to say that a huge number of semiconductors is listed in this one. It lists the parts numbers of five suppliers: NTE Electronics, Philips ECG, Radio Shack, RCA and Zenith. It is ideal for the technician who deals with a wide range of equipment for which replacement parts are not easily available or are of varying origin. The book is available for $34.95 from Altronics Distributors, 175 Roe St, Perth. Phone (09) 328 2199. ...•.... -~---·:•--~ .· . -·.•K ··, . · / ..~·-·· .. , ._ ~: j . ,. i . . .................. '\A ;.•.•.1: >..•(:1 . YBA ; ""} well as typical component values. The book is available at $19.95 from Altronics Distributors, 175 Roe St, Perth. Phone (09) 328 2199. SC DECEMBER1991 81 GREAT SIGHTS AND SOUNDS FROM ROD IRVING AND ARISTA ~· \P-· TV/ANTENNA MUSICAL ACCESSORIES CD ACCESSORIES INLINE SIGNAL AMPLIFIER MIDI EXPANDER Reduces signal loss that occurs with splitters and long cable runs. This MIDI (Musical Instrument Digital Interface) is a parallel box designed eapecially for digital interfacing of mo ■ t keyboards, sequencers and musical instruments with 5 pin DIN MIDI socket oU1puta. Switching allows one keyboard/sequencer to control up to eight keyboard s •••-/sequencers to control up to four keyboards each. Power supply: DC 9·1 2 volts •100mA PP112 plug pack (not supplied.) Inputs: 2 x 5 pin DIN sockets OutpUls: 2 lines of 4 x 5 pin DIN aocketa • Can also be used with antennas, coaxial feed lines and VCR'• • Inputs/output: 75 ohm coaxial sockets. • Power: 2VDC 100mA power pack supplied. ADJUSTABLE CD/AUX TWO WAY INPUT SWITCH L15043...........................................$49.95 Allows amplifiers with a single auxiliary input only to accept compact disc players as well as adding an other auxiliary input to the system. Variable gain ensures the output signal of the CD player m atches the input signal of the amplifier. A11510 ........................................... $39.95 A12014............................................. $109 • ~ - - - - -- - - - -- - - - - UHFTOVHF TUNA BLEDOWN CONVERTOR <O• Allows television sets with UHF only to receive UHF.• Receives both "on air'" and "off air"' UHF signals. • Leta you receive UHF channel 28 and many computers, VCR'• without having to buy a complete new television ..,. • Converts TV games. computers with UHF signal outputs to VHF. • Power supply: 240 volts AC/50Hz. L 15021 ........................................... $99.95 ~ ~ , :.:: '; ----....;:J DO·· ' ' ~ QUARTZ GUITAR TUNER WITH LED INDICATORS CD/TUNER TWO WAY INPUT SWITCH Designed to let you plug in your compact disc player into your amplifier via a tuner input Ideal for systems that do not have dedicated in put for a CD player. Two way switch allows switching between CD and tuner without reconnecting input and output leads. • JnpUI: 2 pairs of RCA aocketa for CD and tuner • Output: 1 pair of RCA sockets for the amplifier High quality tuner with a quartz crystal oscillator which generates a reference tone for accurately tuning guitar & bass string vibration s. • 6 settings for different length, thickness and tension atringa. • LED's lndlcsta the tone being generated & which string it refers to. • In-built microphone allowa testing of accoustic instruments and morel A11520 ................................ $39.95 ······················································$74.95 75 ohm switch connects to yourTV and selects between any two 75 ohm devices. • 2 x 75 ohm sockets in• 1 x 75 ohm plug out • Suitable for selection between your VCR and computer. L11040 .............................................. $6.95 WIRELESS STEREO TRANSMITTER This wiresess stereo audio transmitter allows portable compact disc and cassette players to be used with any FM tuner/radio . Ideal for the car, boat, or home Hi Fi system. Simply play the disc or cassette and tune in the signal on the FM tuner. Can also be used with radio headphones • Automatically ■ witchee itself on and off. • Mono or stereo signal ■ can be received. A1 6100...........................................$69.95 __ VARIABLE SIGNAL ATTENUATOR attenuation is variable from O to20 dB. L11054••i'9. ... • 75 ohm plug to 75 ohm socket. ------- • lnline installation. $a. • _ . .i . ,;;::. • Cuts oU1 TV aignal overload. Easy to install and D ,e - - mdQ1 95 GUITAR AND MIC AMPLIFIER Thi• portable 240VAC mains operated amplifier is not only portable but Is easy and quick to set up. It haa lnpU1• for a microphone and.musical Instrument Ideal for announcing (le. ahop specials, sales etc.) busking or guitar practice. • Microphone Input. • Volume Control. • Musical lnetrument Input • Baas b'eble control • Headphone oU1pU1 for monitoring • Power Indicator • Maxlmun power 10 watts 6.5" full range apeaker •13.8 VDC optional po\'ier lnpU1 • Handy carrying handle • Dimentiona: 260 x 245 x 120mm A14456 ..•........•...........................$149.95 FOUR WAY SPEAKER SELECTOR SWITCH THREE WAY TV SWITCH Stereo speaker selecting switch allows four pairs of speakers to be connected and run off one amplifier output. • Amplifier protected • Each pair of speakers can individually be switched on or off • Either one pair of speakers can Individually can be on 75 ohm switch connects to your TV and selects up to three 75 ohm devices. • 3 x 75 ohm sockets in 1 x 75 ohm plug out. • Suitable for se lection between your VCR, computer and one other 75 ohm device. • Mounting flange with screw holes. • Use 75 ohm load re sistor "RZ20r' if any of the inpU1 sockets are not uaed. • Saew terminating input• and output■. L11041 ............................................ $14..95 ........................................................ $29.95 1imu1taneously. • input impedance: 8 ohms • Output Impedance:& ohms ROD IRVING ELECTRONICS Pty. Ltd. ACN .005 428 437 HEAD OFFICE: 56 RENVER RD, CLAYTON. PH: (03) 543 2166. FAX (03) 543 2648 CITY 48 A'BECKETT ST. MELBOURNE. PH. 663 6351/6391640. FAX: 639 1641. OAKLEIGH 240C HUNTINGDALE RD OAKLEIGH PH: 562 8939 NORTHCOTE 425 HIGH ST. NORTHCOTE, PH. 489 8866. FAX: 489 8131. SYDNEY:74 PARRAMATTA RD, STANMORE. PH: (02) 519 3134. FAX: (02) 519 3868 BLUESTAR COMPUTERS: 271 MAROONOAH HWY. RINGWOOD. PH: (03) 870 1800 16 CHANNEL STUDIO PATCHBOX Ideal for studios, bands and audio workshops. Two banks, each with 16 pairs of socket& designed lo accept effecta pedal•, musical instruments. amplfiera, mixers equalizer etc. • lnputs/OU1puta: 2 x 16 6.35mm mono phone aocketa • Mounting: 19" r ■ckmount or freeatandlng • Dlmentlona: 460(L) X 45(H) x 95(W)nvn .....•.......................•.•.•.........•.•.......... $179 Postage rates $1 • $9.99 ... -.$3.00 The• poolage $10 • $24.99.. $3.50 r••• are bnlc $25 • $49.99.. $4.50 poolage only up lo :.':it. r::~':'gh~ $50 • $99.99.•$6.00 $100 • $199 ... $7.00 immo wtll be $200 • $500._FREE c:lmgod at dlffofont $500 PLUS .. FREE All salrs tax exempt orders to : RITRON ICS WHOLESALE 58 Ronver Rd, Clayton. Victoria . Ph: (03) 543 2168 Fax : (03) 543 2648 MAJL ORDER & CORRESPONDENCE P.O BOX 820, CLAYTON , VICTORIA. 3168. En-on• OffWn•it0n• excap .. d. Prlmt I. apec:itlcaHone autJtect to change. FLOPPY DISK DRIVE SPECIALS! ...~ . ·~ JAPANESE DRIVE SPECIALS 1.44MB 31/2" 1-9 10+ $99 $95 1.2MB 5 1/4" 1-9 10+ $129 $119 PHAXSWITCH Lets you connect a normal telephone handset and a fax to the same telephone line. • Detects whether an incoming call is for the phone or fax and automatically puts it through to the correct unit. • It automatically switches when you pick up the phone or use the fax to make an outgoing call. SAVE $20 this Month! X19090 ............. $269 THE BUTTON SPIKE PROTECT OR Surges and spikes are caused n01 Jnly by hghin,ng stri kes and load RITRON MONITOR sw 1l ching bu1 also by other equ1pmer.1 1· being switched on and ott such as fluorescent lights elec1r1c motors fndge free 1ers air cond1t1oner s e1 c For etfect1ve pro1o ct1on such spik es mus! be stopped belore they reach you r equipmen t Simp ly p!ug The The Sulton employs un ique metal ox id e var1s1rr wr.hnology and will SPECIFICATIONS, Vollage 240V Nom1na 1 To tal Energy Ra 11ng 1SO 1o ulP.., Re sponse Time 1Ons Pro1et1to n Level 3~0V Pf'dk $42.95 MAGIC STAGE A working bench for your Mouse . •H i gh qua,lity ABS plastic and ant i- static rubberised t op ·Stationary holder •Includes pull -out shelf tor ·Dimensions : 28CJ x 260 x 25mm · Fits over keyboard c 21 oao On special was $24.95 Now ....... $14 .9 5 6 PROTECTED POWER OUTLETS Ideal for protecting personal computers . video equipmen1. colour TVs. amplifiers , tuners, graphic equaliser;i , CO players etc . . • 3 x Metal Oxide Varistors (MOV) • Maximum clamping Voltage : each MOV: 71 C volts at 50 amps • Response time : Less than 25 Nanoseconds. X10086 ..... ................ $69.95 I .. ... ..,. ' ,. , -•~ as.,23 PC IBM PACK INCLUDING JOYSTIC K ADAPTOR CARD (15 PIN) C14 21 7 .......... $74 .95 ~ i OS·129NIF SPACEAGE CONTROL NINTENDO & MULTISYSTEM COMPATIBLE (7 OR 9 C14 21 4 ..........S3 9. 9 PIN) QS.130NIF DELUX DIGITAL NINTENDO & ,· MULTI SYSTEM COMPATIBLE (7 &9 PIN) C14209 ...... , .. .$39.95 OS·131 NEW BASIC ATARI I COMMODORE .g PIN C14218 ......•.. .$19 .95 Button rn to an o utlet and 11 wil l pro te c1 ' all equ 1prn en1 plugged in to ad1acen1 o u tl e ts on 1t1e same br anch c1 rc urt d1ss 1pa. !e 150 1oulcs o! elect ncat energy mearly twice that o1 comparable surge r\rr es1e,.., 1 Quick Shot offers the moat complete selection of video game controllers in the market Modelo are available to auit all the moat popular video game machines and just about 3 YEAR WARRANTY This stylish & reliable monitor has been designed for Australian conditions & comes with a 3 year warranty. Spees: CTR : 14" 90° deflection, dark-tint, non-glare. Display Size: 245+/5mm x 180+/-5mm Resolution: (max) : 1024 x 768 Dot Pitch : 0.28" --~_,_ _. === =~ . :~ -i----r-";.r =.: . :.· -~- ~- --■ :....~ ::~·l~· -t ~1 _. .!II 286- 12/16....... ............... $159 286-16/21 ......•.......... .....$199 386SX-10/20 ..•.......... .... $350 386SX-20/27 ................. $375 386-33 WITH 64K CACHE ........ .•........ $750 386-33 WITH 128K CACHE ..... .......... $895 386- 40 ...................... ... .$795 486SX -20 ............ ....... $1195 X14532 ................ $479 rWHAT'"SNEW1, f"WFfArS-Nl::W?, \..<at>:) I~ BUDGET MOUSE MOUSE HOLDER Microsoft compatible • Stylish & ergonomic design gives a unique feeling of pleasure & comfort In your hands. • Feature touch button control • Stream-lined design, glossy finish • Smooth well•balanced gliding Handy mouse holder attaches to the ·side of the 1 1 computer or monitor for I storing a mouse when not in use. It is supplied t with adhesive velcro so the mouse holder can be easily removed from the computer or monitor if required . Will accept a mouse with maximum demensions of 65mm wide & 35mm th ick C21064 •• •••••. .•.•.• $3.95 AN AMAZING $29.95 . Sound blaster II is the ultimate sound board that easily plugs into any internal slot in your IBM•, PC, XT, AT, 386, PS/2(25130) & compatibles. FEATURES: • Text to Speech synthesizer • 11 vioce FM Music • Digitized Voice Input & Output • Midi interface • Built-in joystick port • Power amplifier & Volume Control • Bundled software : SBTALKER with Dr SBAITSO VOXKIT •Voice development tools Talking Parrot FM Intelligent organ Only................ $249 PRO •• . FREE SPACE QUEST 1 with every Sound Blaster II. The All-in-One sound card. SOUNDS BLASTER MOTHERBOARDS SUPA VGA COLOUR MONITOR SOUND BLASTERS SOUND BLASTER II I - ···· • 16 Bit card • Stereo DAC with hardware ADPCM • Stereo Recording for line-in and co.Audio • Stereo 22 voice FM music Synthesizer • MIDI interface co.ROM Interface built-in • Text to Speech Driver. • Secectable IRQ and OMA • Power amplifier built-in Bundled Software: Ml DI Adaptor & sequencer FM Intelligent organ VEDIT: Voice editor & Utilites CD Music player MMPlay Presentation Only....... ... ....... . $420 :: :~ ·..i; ·; ; ~ USING MS-DOS 5 The most helpful DOS book available has now been updated for DOS 5 so you can achieve DOS success in easy steps. Real world analogies and examples guide you to confidently write batch files and Macros. Includes a DOS survival guide giving trouble- shooting advice. .• .. $51 .00 &.o. USING WORDPERFECT 5.1 2nd EDITION. Discover the secrets to success for over 100 000 users I This classic best seller expertly leads you from basic techniques to advanced Word Perfect operations, with detailed coverage of all new features. ······················ $57.95 USING MICROSOFT WINDOWS3 Adv ance to power user status with hands-on exercises for learning Windows basics. Then customize yoUr system using usful tips. This handy reference also teaches you Windows Paint & Windows Write. ...................... $51.95 ["TOP SELLING SOFTWARE-PRODDcfs--7 IMICROSOFT WINDOWS VERSION 3 ............... ...... $165 i !MICROSOFT WORD .............. ..............................••... $499 1 :MICROSOFT WORD FOR WINDOWS ......•••....•...... $499 : I :MICROSOFT FLIGHT SIMULATO ttt ··················$79 ·· ........ $230 1 I MICROSOFT WORKS .................... ' :woRD PERFECT....... ...... ........ ...... \ . . ..... $499 1 1XTREE GOLD ..... ................. ........ ~· ~ · ...... $195 lPC TOOLS VERSION 7 ............. , ···, ..... •.. $275 :LAP LINK 3 ................................~ ~ ·. /_.. ••.... $225 L--------------- ------- -- \PRODUCT SHOWCASE I High performance 51/2-cligit multimeter This benchtop multimeter has a performance which would have been regarded as close to laboratory "standard" not many years ago. It measures AC and DC volts and current plus resistance. For AC and DC volts, it has five ranges with full scale readings of 200mV, 2V, 20V, 200V and 1000V. For AC and DC current, there are four ranges with full scale readings of 2mA, 20mA, 200mA and 2A. For resistance, there are seven ranges with full scale readings of 200Q, 2kQ, 20kQ, 200kQ, 2MQ, 20MQ and 200MQ The resolution on any of these ranges is a function of the 5½-digit display and the integration time for the measurement which is selectable via the front-panel buttons. This can range from 1.2 milliseconds up to 100ms, although maximum resolution is obtained with an integration time (ie, reading update time) which varies according to the parameter being measured. For example, on the 200mV range , the maximum reading is 199. 999m V and the resolution is 1 microvolt. On the 200Q range, the maximum reading is 199.999Q and the resolution is 1 milliohm. . The accuracy on any range is also a function of the integration time and is specified for periods ranging from 24 hours to one year (from time of calibration). For DC voltage, the 1-year accuracy is quoted as ±0.008% + 3 digits on the 2V range. For AC voltage, the accuracy also depends on the frequency being measured, which can be up to lO0kHz. For example, on the 2V and 20V ranges, the accuracy is ±0.2% + 100 digits for frequencies between 45Hz and 10kHz. For AC measurements, the 7551 is calibrated to read RMS values for sinewave inputs. For the 7552 model, a true RMS rectifier is employed. The allowable crest factor for the 7552 is 3. In addition, the 7552 also provides frequency measurement up to 200kHz and its input sensitivity in this mode is 5% of the relevant AC voltage or current range selected. For DC voltages, the input resist- ance on the 200mV and 2V ranges is quoted as greater than 1 gigohm (lGQ), while for the other DC voltage ranges it is 10 megohms (lMQ). The 7551 (and 7552) is available with RS-232C or GP-IB (IEEE 488) interface and comes standard with a memory card slot for additional custom functions. Truly, these are exceptional instruments, particularly when the purchase price is considered. This ranges from around $1400 plus sales tax where applicable . For further information, contact Tony Richardson at Yokogawa Australia Pty Ltd, Centrecourt D3, 25-27 Paul Street North, North Ryde, NSW 2113. Phone (02) 805 0699. Laminator for cards and documents The best way to protect and preserve precious documents, photos, cards and other types of paper thin objects in a waterproof airtight seal is to laminate them. This laminator from Synlix can accommodate plastic sleeves up to 100 x 150mm. During laminating, the unit bonds the laminate sleeve to the item being processed. It makes a permanent seal and the photo or card cannot be removed. A recommendation is made in the instructions that self-developing photographs should not be laminated. The laminator is available, along with two standard size lamination sleeves (one credit card size), from all Jaycar Electronics stores at $99.95. Phone (02) 743 5222. 84 SILICON CHIP - f!JtJ.-<:!Jo ... ~ "':;"· '"'$ SvfiliX Test pattern generator for video monitors Pattern generators for PAL TV sets are readily available (eg, see this month's article on the TV pattern generator) but a generator suitable for the wide range of computer video monitors is a rare beast indeed. Enter the Blackstar 1410 video monitor tester. It produces the full range of patterns: testcard, raster, vertical lines, crosshatch, dots, checkerboard, border and colour bars. More importantly, the Blackstar is suitable for the following computer monitors as well as standard PAL and NTSC colour sets: MDA (mono), CGA, EGA, VGA, SVGA (600 and 768 lines) and PGA. Depending on the monitor type selected, the line scan frequency can vary from 15.625kHz to 48.5kHz, while the field rate can vary from 5087Hz. The test pattern outputs are available as composite and RGB signals from BNC sockets or from 9 and 15- ELECTRONIC WORLD DISPOSALS Common transistor pack over 60 for just Varistors 230V surge protection only 60c each BA317 (similar 9148) pin D-type sockets to suit the majority of currently available monitors. All the signals and monitor types are selected via pushbuttons on the front panel and the mode is indicated on a liquid crystal display. For further information on the Blackstar 1410 video monitor tester, contact the distributor, Len Altman, Obiat Pty Ltd, 129 Queen Street, Beaconsfield, NSW 2014. Phone (02) 698 4776. $2.80/100 Bulk capacitor packs Wima's, polycarb, disc etc $9.30 Variable gang capacitors open gang receiver type $6.95 12" sq blank PCB $4.00 DB25 right angle female $2.50 Assorted Hivolt capacitors 80c Silver mica capacitors 30c Electro's 100µF 160V $1.30 Electro's 10µF 40V $2.20/100 RF inductors assorted values from 60c to $1.30 Put your mouse on the stage If you are constantly having to clear an area on your desk to use Windows or any other program that uses a mouse, this may be the ideal solution for you. Called the Magic Stage, it sits on top of your keyboard and is a worktop for your mouse. There is also a sliding shelf to keep the mouse on when it is not being used. The Magic Stage is made from ABS plastic and has an anti-static rubbetized pad. It also has a compartment to place pens etc, and simply folds away $6.95 Relays 12V SA PCB mount $2.00 Filters 21 MHz 10-pole 15kHz 1.SkQ $20.00 High intensity LED's $16.00/100 BUZ90 power FETs $4.75 1 amp Triacs only 45c each Used AA nicads 700mAh 60c each when not in use. It has been designed with a sloping stage to allow for easy hand manipulation of a mouse. The unit is available from Rod Irving Electronics, 64 Parramatta Rd, Stanmore NSW, or from their Melbourne stores. .,.~~.;r..~:r:.h: 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. Rotary switches Oak type $5.50 Wafer type $2.55 5mm former & cores now 50c Coaxial relays $36.00 Bulk ICs at low prices 8049 X 9 LM324 x 25 CD4049 x 25 TL082 x 50 $18.00 $10.55 $12.00 $35.00 Numerous components all reduced to sell. Come and browse and sweep up the bargins. Electronic World Disposals 27 The Mall (Cnr Eastfield & Bayswater Rds) South Croydon, Vic 3136 TelP.phone: (03) 723 2699 DECEMBER1 991 85 Spectrum analyser has intuitive user interface played in AM or FM video monitor mode. An optional internal tracking generator allows swept frequency measurements to be made. Weighing only 10kg, the Tek 2712 is an easy to use portable package. For further information, contact Tektronix on (02) 888 7066. Russian-made shortwave radio Tektronix has just released a new VHF /UHF spectrum analyser with a frequency range from 9kHz to 1.8GHz. It has a high dynamic range, excellent frequency accur:acy and an intuitive front panel interface that is menu driven. The main function controls are dedicated, while other functions are accessed via a keypad. The display provides 4-trace digital storage with analog display capability. Signal counting to lHz resolution and 0.5ppm is possible with its internal frequency counter, while built-in audio demodulators give identification of AM or FM signals. Broadcast and satellite television signals can also be demodulated and dis- UV PROCESSING EQUIPMENT e KALEX LIGHT BOXES UV2 Exposure Area 40cm x 27cm $750.00 • Portuvee 4 Exposure Area 25cm x 14cm $250.00 • Portuvee 6 Do you have a hankering to own a shortwave radio that you can tune with a proper dial instead of a digital display? If so, this radio could be for you. The unit is tunable over the range 150kHz to 18MHz in seven bands: long, medium-wave and five shortwave bands. It also covers the broadcast FM band (in mono). Made in Russia, the unit has an extendable whip antenna, a tuning indicator and a large rotary band selector. Bass and treble controls are featured and the unit can be run from internal batteries or the 240VAC mains. It retails for $139.95 and is available through David Reid Electronics, 127 York St, Sydney 2000. Phone (02) 267 1385. Stylish 3-sector alarm module Exposure Area 43cm x 40cm $650.00 3M Scotchcal Photosensitive Riston 4600 PCB Material KALEX All prices are plus sales tax if applicable I VISA I I RI 40 Wallis Ave East Ivanhoe Vic. 3079 (03) 497 3422 (03) 497 3034 Fax (03) 499 2381 ELECTRONIC COMPONENTS & ACCESSORIES SPECIALIST SCHOOL SUPPLIERS 86 SILICON CHIP This flush surface mount alarm control centre features 4-digit keypad access and is tamper-proof. The alarm has three independent protection Is your phone being tapped? Are you the type of person who is afraid that someone might be listening in to your call? Well this is the device for you. It sticks to the side of your phone and connects between your phone · and the incoming line. ·When you are talking normally on the phone, a green light gives the all clear but if the red light flashes, someone might be listening in to your call. It retails for $34.95 from Rod Irving Electronics, 74 Parramatta Rd, Stanmore NSW, or through their Melbourne stores. loops: 24-hour instant, perimeter instant and isolatable interior delay. All loops are terminated with an end-ofline resistor and are compatible with both normally open (NO) and normally closed (NC) loop devices. Communicator, relay, siren driver and buzzer outputs are built into the alarm. All inputs and outputs are provided via a plug-in wiring harness to make for easy installation. Entry and exit times, access code and siren duration are all fully adjustable, making the unit suitable for small commercial premises, apartments and residences. The alarm can also be used as a slave unit for larger combined security systems in professional applications. At $119, it offers good value. Also available is a 4-sector alarm that provides a status display for each zone. Each zone is also individually isolatable and has provision for two siren outputs. It retails for $249. Each alarm has the option of being connected to a remote digital access keypad to allow arming and disarming of the alarm. This allows the alarm module to be hidden for increased protection. For further details, contact Altronics Distributors, 174 Roe Street, Perth WA 6000. Phone (09) 328 2199. DMM has automatic AC/DC selection Autoranging digital multimeters have been around for years but up until now they have not had automatic selection of AC and DC ranges. This new unit from Sanwa, the model ':"IILW-~; CDA-701, now in®,w.·~~ ® <at>® cludes that feature. It will automatically select AC or DC mode when using the voltage or current ranges. Other features in this 3½digit LCD meter include a quick response beeper for continuity checking and a low-ohms range for in-circuit testing. For further information, contact Tony Jones, Warburton Franki Division, Bell-IRH Industries Pty Ltd, 32 Parramatta Road, Lidcombe NSW 2141. Phone (02) 648 5455. UHF corner reflector available in kit form Those who want to build the UHF corner reflector antenna featured in the June 1991 issue of SILICON CHIP but who don't wish to go to the trouble of buying and cutting aluminium will welcome the availability of a full kit for the project. Retailing for $65, including postage to anywhere in Australia, the kit comes with all parts cut and drilled. Contact BDK Audio, PO Box 139, Landsborough, Qld 4550. Phone (074) 94 1928. New soldering station has redesigned heater This new 30 watt iron features a new heater/tip concept in that it has a cartridge type element that sits inside a hollowed out tip. Previous designs had a hollow heater outside a solid tip. This arrangement has the advantage of giving better heat recovery and reduced tip operating temperatures. ANTRIM TOROIDAL TRANSFORMERS For more information, contact Scope Laboratories, 3 Walton St, Airport West 3042. Phone (03) 338 1566. PRESTON ELECTRONICS 217 High Street, Preston, Melbourne Vic. 3072 (Cnr of Bell & High Street) Europ/Jap Transistor Equivelent Book 790 Pages. $39.95 Lab-Tech 20MHz Dual Trace CRO with Probes. $799.00 Economy 15 Watt Soldering Iron - 240V Fine Point Tip . $19.95 Weller WTCPN 240V Soldering Station $150.00 • • • • Now made in Australia Standard range 1SVA 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 Diskettes Precision Quality - Pkt 10 5¼" DS/DD $7.95 3½" DS/DD $14.95 IBM Compatible Disk Drives - Quality Jap. Units 1.2MB, 5 1/4" $195.00 1.44MB, 3 1/2" DS/DD $175.00 1r Mail Order Hot-Line B/Card-Mast/Card-Visa-Cheque Phone (03) 484 0191 DECE~IBEH 1991 87 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. Running the high energy ignition on 6V I have purchased the kit for your High Energy Ignition System (described in May & June 1988) and wish to modify it to run on a 6V coil ignition/ points system. Could you please advise on how I might do this? (K. M., Yarralumla, Vic;). • There is no reason that we can think of why this circuit will not work at 6V. However, we have not tried it at 6V and cannot guarantee that it would run well. We suggest that the 47Q, 100Q, 330Q & 2.2kQ resistors all be halved in value. The speaker protector & rack systems I have a small integrated rack hifi system made by Aiwa. Ever since it was repaired for lightning damage it has had an increased tendency to "thump" at switch-on and switch-off and so I ·intend building the Loud~ speaker Protector described in the July 1991 issue of SILICON CHIP. Since the Aiwa rack system is so tightly packed, there is no chance of installing it inside, so I want to make it as an e2(ternal unit. Are there any UHF antenna not intended for VHF You mention in the article on the UHF antenna in the June 1991 issue that "if all goes well, you should be able to dispense with the VHF antenna altogether". Does that mean that this antenna can be used for TV reception for bands 3, 4 & 5? Will it be suitable in areas with ghosting problems? (G. _D., Morwell, Vic). • Our comment about being able to dispense with the VHF antenna altogether was based on the assumption that all the wanted sta88 SILICON CHIP problems with this? I understand that the Protector needs a connection from the amplifier's signal earth. Can I use the grounding terminal on the back of the unit (normally used for the turntable earth) for this purpose? And what about a signal source to set the AC trip point for the Protector? I don't have any signal source. Can I just tune off a station on my FM tuner and then use the white noise as a substitute for a tone signal? (S. J., Moorabbin, Vic). • There should be no problems with building the Loudspeaker Protector into a box external to your rack system although you will need to fit a suitable terminal strip on it to terminate the wires from your power amplifier and loudspeakers. You can use the suggested mains transformer but you will also need a mains switch to turn the unit on and off. Make sure that all your mains wiring is quite safe and wired in such a way that there is no chance of any mains wires coming into contact with the leads from your amplifier. If you want to eliminate all mains wiring from the interior of the Loudspeaker Protector box, use an 18V DC plugpack power supply and link out the 220Q resistor Rl. tions could be received on UHF. This UHF antenna does respond to signals at the top of the VHF band (ie, channels 9 & 10), but the response is hardly good enough for first-class viewing. Your question regarding its suitability for areas with ghosting problems depends on whether you are asking in regard to UHF or VHF. Its response on the UHF bands is certainly more directional than an equivalent VHF antenna and so, in this regard, it should help eliminate ghosts. It certainly will be no good on VHF, ghosting or not, for the above reasons. It is OK to use the amplifier ground terminal. Alternatively, you could use one of the loudspeaker earth wires from the amplifier. You could use the "white noise" signal from your FM tuner to set the trip point although the resulting setting will not be very precise. Still, in the case of a rack system which can only deliver 20 to 30 watts, that will not be critical. In fact, you could just leave VR1 set fully clockwise (for maximum sensitivity) and that would be good enough. (GND) Instability in balanced line drivers Some time ago, I built several of the balanced line driver/receiver boards described in the December 1989 issue of SILICON CHIP, mainly to drive recording equipment or power amplifiers several metres from the control amplifier equipment. The boards performed OK initially when bench tested and there were no obvious problems with them driving short lengths (up to two metres) of twin cable. Recently, I had need to drive other power amplifiers about 20 metres away from the control equipment and I used the balanced line drivers for this. The sound reproduced by the power amps had a "grainy" quality, and a check with a scope revealed that very high frequency oscillation was present at the line receivers, this being generated by the line drivers. The inverting op amps, IC2b/IC4b, were oscillating, obviously due to the capacity of the cable. This suggests that the inverting op amp is having its feedback shunted at HF by the capacitance pf the cable which interacts with the 33Q output resistor. My conclusion (and fix) was that the inverting op amp• really should have a small capacitor (say 100pF) from pin 1 to pin 2 (across the whole feedback network) to roll the gain off at HF. This raises the following questions: (1) Is the solution I used the most elegant or might there be a better solution? Is there a better value than 100pF? (2) Should the line end at the receivers be terminated in something nearer the characteristic impedance of the cable? If the op amps won't drive a low impedance (600Q), would an additional 10kQ resistor between the legs of each line (conductor to conductor) be worthwhile? (3) Is there an absolute maximum line capacitance the drivers will drive? No limits or restrictions for this were specified in the original article. I had planned to drive another "suite" of equipment through a further 20 metres of cable but with the drivers at the approximate midpoint of the cable, I fear that the driver inverting op amps may not like the additional capacitance! (K. M., Silverstream, NZ). • We have not experienced the problem of instability but then we have not used them with very long lines. Your theory as to why they oscillate seems plausible as does your cure, although possibly a small stopper resistor (say 33Q) in each output leg would give a better result. It is not usual audio practice to terminate the cable in its characteristic impedance - use 600Q. There will clearly be a limiting capacitance which the op amps can drive - we would not recommend anything above a few hundred picofarads. Advice on 100V line PA systems I am writing to you in the hope that you may be able to help me with a technical problem I have. It concerns the PA system at St Brendans College, a boys ' boarding college located at Yeppoon, Qld. The system is a large one, consisting of 60 internal speakers and 12 external ones, being driven by three 100 watt PA amplifiers controlled through the PABX. The external side of the system, consisting of horn speakers operating on a 100 volt line from one amplifier, seems to operate OK. My major problem concerns the internal network which mostly consists of Aiphone intercoms being used as speakers only. These have a small 20Q speaker inside, being driven on a 25 volt line from one amplifier, without using audio line transformers. The How do traffic signals operate? What is the principle of operation of traffic signals? As I live on a farm, our front entrance is some distance from the road, and I have arranged for the gate to open automatically during the day and at night (under the influence of car headlights). The sensor is an LDR. The difficulty is that, at night, a vehicle with poorly adjusted lights will not always activate the system. · So, I would like to try another scheme, operating in conjunction with the existing one, and wonder whether the type of sensing used in traffic signals could be used. I think some type of pickup coil is used under the surface of the road, but have no other knowledge of the matter. obvious result of all of this is that the amplifier runs extremely hot. Having discovered this, I am changing all the internals to small horn speakers and multi-tapped audio transformers with the intention of operating it on a 100 volt line. I understand that 100/70 volt lines are used for distance transmission with the ability to run a large number of speakers on them, but having had nothing to do with PA systems until now, I need advice. Could you please explain how the maximum load is calculated? For example, if I am using multi-tapped transformers with say a 10-watt tapping in five rooms and 5 watt tappings in another five, is the total load 75 watts or because the amplifier is never being driven at full output do you allow a nominal figure of say 3 watts per unit, making a total load of 30 watts? Also, how many units can be run in parallel before you start blowing output fuses? Could you also tell me if it is permissible to connect the inputs of the amplifiers in parallel without causing problems? Any advice you are able to give me would be very much appreciated. May I also congratulate you on your excellent magazine. Keep up the good work! (R. C. , Do you have any information on this? The electronics of the system should not be any problem, just the type and configuration of the sense coils (or whatever else) is used. Hoping that you can help. (R. G., Mt Bryan, SA). • We have no information on this subject but we can comment on their likely operation. Coils are buried beneath the road surface and the system is designed to react to the change in inductance caused by the large metallic mass of a car passing immediately above them. Have you considered a non-electronic solution? Self-opening gates are available, operated by a nudge from a vehicle but unable to be opened by cattle. On the other hand, they do have the drawback that they can be damaged if they are "nudged" too heavily by vehicles. North Rockhampton, Qld). • Your example for calculating the maximum load on the amplifier is correct. You should assume that the amplifier is to be used at full power and then add up all the power settings on the supply line speakers and it should not come to more than the power rating of the amplifier. It is permissible to connect the inputs of amplifiers in parallel, provided their outputs are not connected in any way. Modular 4-channel lighting desk What's the possibility ofreleasing a "modular" version of the 4-Channel Lighting Desk? I am about to build it as is but would really like to be able to build up a 20-30 channel unit (fixed) for stage use in our church hall. The principle behind the desk is great! Obviously each channel module would ne-ed some kind of buffer to prevent loading and there would also have to be a "master" module to drive the channel modules. (D. P., Wagga Wagga, NSW). • We are not keen on the idea of a modular version of this project as a multi-channel desk implies a much bigger lamp load and therefore a reDECEMBER 1991 89 Converting RMS to peak-to-peak values For some ofus non-professional electronics enthusiasts it is one thing to interpret formulae but quite another to find the right one. The one I am having trouble finding at present is the one which converts volts peak-to-peak to or from volts RMS. The Studio 200 power amplifier (SILICON CHIP, February 1988) requires 1.5 volts RMS to drive it but a guitar preamp which I built recently has a quoted output of 20V peak to peak. Having overdriven the power amplifier tg,_ destruction once, I wish to make sure there is no mismatch between them. I suspect that 20V peak-to-peak is far too much for the Studio 200. Also, how can one measure output voltages such as these with an analog multim- quirement to run the whole system from 415V 3-phase AC. This is not to say that we will not consider doing a multi-channel lighting desk in the fu. ture. However, whether or not we go ahead with such a project will depend on the overall interest in the 4Channel Lighting Desk. Using the lighting desk as a slave controller Can the circuitry for the 4-Channel Lighting Desk drive the Triacs remotely? If so, what extra circuitry would be required to drive them from 30 metres? Could you recomme'n d a connecting cable and will I need a driver to compensate for power loss? (D. P., Rochester, Vic). • We are not sure from your letter whether you want to split the 4-Channel Lighting Desk into two separate sections or whether you want to drive additional Triacs separately. Possibly the easiest way to drive the Triacs remotely would be to run the low voltage optocoupler signals from the lighting desk to the Triacs. This should be satisfactory over a range of 30 metres but we have not tried it. The more correct (and industry standard) way of doing it would be to use the four 0-lOV signals present at 90 SILICON CHIP eter as not all hobbyists can afford or have access to a scope. (J. S., Taringa, Qld). • To convert an RMS sinewave voltage to a peak-to-peak voltage, multiply it by 2.828 (or about 2.8). For example, 1.5 volts RMS (sinewave) becomes 4.242 volts peakto-peak. 20 volts peak-to-peak is equivalent to 8.77 volts RMS, a figure too high for any power amplifier, although we suspect that this is the maximum output voltage your guitar preamp can deliver, not its nominal output level. You can measure RMS sinewave voltages up to at least 1kHz with most analog multimeters and digital multimeters. Have a look in the user manual for your multimeter and you will generally find a specification for the AC frequency response. the cathodes of diodes D8, D9, DlO & Dll. These DC signals would then be fed to the four comparators (eg, IC3), preheat circuitry (IC2c) and zero voltage detect and ramp circuitry preceding the optocouplers. However, we do have a strong caution. If you are thinking of using the 4-Channel Lighting Desk to control additional banks of lamps, they will have to be operated from a separate phase of the mains supply because the existing phase will already be fully loaded. Going the 3-phase route is a step up in circuit complexity and one we don't recommend unless you are fully conversant with this area of mains circuit design. 10-RPM resolution for tachometer I was very pleased to see the Digital Tachometer in the August issue of SILICON CHIP but disappointed that the resolution didn't go down to 10RPM instead of 100RPM. I can appreciate the engine variations in a car but this is not such a problem in a boat or aircraft engine where the load is smooth. I suspect that there are a lot of boat, ultralight and homebuilt aircraft owners who would like to used this tacho. In the case of aircraft, setting the correct mixture at altitude, without the aid of an exhaust temperature gauge, involves accurate setting of the revs. At some future time, would you consider publishing the additional circuitry to utilise the "10s" digit also. (R. W., Yungaburra, Qld) . • We don't think it is worthwhile designing the circuit for 10RPM resolution. You will find that all internal combustion motors, regardless of whether they are used in boats or aircraft, still ha_ve quite significant speed variations, even on a constant load. These variations are barely noticeable on an analog tachometer because its mechanical and electrical damping tends to filter out the variations. On a digital tacho , the variations are painfully evident, hence our decision to design for 100RPM resolution. Nevertheless, we may publish the necessary circuit modifications in the "Circuit Notebook" pages of a future issue. The wonderful world of General Electric I was recently given an old General Electric TC2OTI colour TV set (not working) to do with what I liked. The TC2OTI was fitted with the Hitachi PAL3 chassis. A quick check with the multimeter proved that the HT rail was working but the 20V rail was not (0V). To cut a long story short, the fault was traced to R731 which had gone high (approx. 6MQ) and was rather charcoaled looking. Problem: what is R731 's value? A guess of 100W got it working and showed up other faults: arcing in the focus network, R759-R760 1.5MW open circuit; and the 20V rail at 14V, C753, lO0µF 25V electro open circuit as per TETIA TV Tip in a recent issue. But my problem is what is R731? Charcoal is hard to read. (S. S., Zillmere, Qld). • Is there any hotshot technician out there who knows how to read charcoal or who knows the value ofR731? Notes & Errata PC Talking Voltmeter, October, November 1991: diode D4 on the circuit diagram of page 57 of the October issue is shown connected the wrong way around. SC ~~ORDER FORM / USE THIS FORM FOR ALL YOUR SILICON CHIP PURCHASES SILICON CHIP BINDERS: Yes! Please rush me _ _ _ SILICON CHIP binder(s)<at> $A14.95 each including postage. (Overseas orders please addA$3 .00 each for postage). Total $A_ _ _ __ SPORTS SHIRT: Please send me _ _ _ Sport Shirt(s) <at> $A24.95 including postage. (Overseas orders please add $A3.00 for the additional postage). Size(s): S(Qty)_ M(Qty)_ L(Qty)_ XL(Qty)_ XXL(Qty)_ . Total $A._ __ BACK ISSUES: $A5.00 each (including postage). Overseas orders add $Al.GO per issue for postage. YEAR ISSUE YEAR ISSUE ISSUE YEAR ISSUE YEAR TOTAL$A SUBSC RIPTIONS: RATES □ NEW SUBSCRIPTION: Month To Start □ RENE WAL:SubNo. (PLEASE TICK ONE) Start In Australia □ GIFT SUBSCRIPTION: Month Th Start Your Details Address Postcode 1 year (12 iss ues) O$A84 O$A42 Australia with Binder(s) O$A105 O$A53 · □ $A130 O$A65 Overseas Surface Mail O$A130 O$A62 Overseas Airmail O$A240 O$A120 NZ & PNG (Airmail) Mr/Mrs/M s: 2 years (24 issues) Daytime telephone number. _ _ _ _ _ _ __ Enclosed is my cheque/money order for $_ _ __ ordebitmyO ._ D ~~ II Di vM I II~I~~ Card expiry date Sign at ure _ _ _ _ _ _ _ _ _ _ _ _!_ _ l pax \ Rill (02) 979 6503 F ax the coupon with your Credit Card details 24 Hours, 7 Days a Week -=z:lt Gift Subscription Details Message: _ _ _ _ _ _ _ _ _ _ _ __ _ _ Mr/Mrs/Ms: _ _ _ _ _ _ _ _ _ _ _ _ __ Address: _ _ _ _ _ _ _ _ _ _ _ _ _ __ _ _ _ _ _ _ _ _ _ _ _Postcode_ _ __ (02) 979 5644 9am - 5pm Mon-Fri. Please have your Credit Card details ready. Mail coupon to: FREEPOST25 Silicon Chip Publications PO Box 139 Collaroy Beach NSW 2097 No stamp required in Australia Index to Volume 4: January-December 1991 Features 01 /91 04/91 04/91 05/91 06/91 07/91 07/91 08/91 09/91 10/91 11 /91 12/91 6 Take Care Servicing Microwave Ovens 16 Canon's New Still Video System 72 Hewlett Packard's Model 54600 100MHz CAO 4 How To, Install Multiple TV Outlets, Pt.1 14 Tuning Into Satellite TV, Pt.1 6 How To Install Multiple TV Outlets, Pt.2 18 Tuning Into Satellite TV, Pt.2 4 Tuning Into Satellite TV, Pt.3 12 Plotting The Course Of Thunderstorms 8 Road Testing The HP54601A 100MHz CAO 7 An Ultrasonic Detector That Does Not False Alarm 6 The Miracle Computer Music System Electrical Energy 01/91 98 Pt.6 Tasmania's Hydroelectric Power System 02/91 92 Pt. 7 Tasmania's Hydroelectric Power System 03/91 82 Pt.8 High Voltage DC Transmission Systems 05/91 82 Pt.10 High-Power DC Transmission Lines 07/91 96 Pt.11 The Snowy Mountains Hydro Electric Scheme 08/91 7 4 Pt.12 The Snowy Mountains Hydro Electric Scheme 09/91 88 Pt.13 The Tumut 3 & Murray 1 Power Stations 10/91 86 Pt.14 Making Electrical Energy Use More Efficient 11 /91 86 Pt.15 Heavy Electric Vehicles In The Mining Industry 12/91 76 Pt.16 Pressurised Fluidised Bed Combustion Electric Vehicles 01/91 14 The State Of The Art 02/91 8 Energy Storage - An Eldorado For Innovators 03/91 6 Motor Control - The Part Played By Electronics 03/91 10 Solar Electric Speed Record 92 SILICON CHIP 04/91 6 The World Solar Challenge 05/91 1O Motors For Electric Vehicles 06/91 6 Electric Vehicle Transmission Options Design & Theory 02/91 14 A Practical Approach To Amplifier Design, Pt.1 03/91 38 Data On The LM383 7W Audio Amplifier 04/91 64 A Practical Approach To Amplifier Design , Pt.2 06/91 59 Howl Suppression For PA Systems 09/91 4 The Highs & Lows Of AID & DIA Conversion Vintage Radio 01/91 42 My Fancy European Models 02/91 40 One Thing Leads To Another 03/91 42 Automatic Gain Control: How It Works 04/91 36 Converting An Airzone To AGC 05/91 18 All About Regenerative Receivers 06/91 78 Restoring A 4-Valve Howard Receiver 07/91 14 Some Simple Repair Techniques 08/91 82 Getting Out Of Trouble Again 08/91 14 A Step-By-Step Approach To Vintage Radio Repairs 09/91 82 Transistor Radios Are Worth Collecting 10/91 72 Two Vintage Radio Museums 11/91 78 A Simple Junkbox 2-Valve Receiver 12/91 32 Power Supplies For Battery Receivers TETIA TV Tips 01 /91 02/91 03/91 04/91 05/91 06/91 72 76 26 43 70 57 Rank C-1851 Sanyo CTP5604 Hitachi CTP-229 Mitsubishi/AWA AV10 National TC2001 A Hitachi CEP288, CEP 289 (PAL3A Chassis) 07/91 47 AWA AV11, Thorn TR101 VCRs 09/91 40 General Electric TC20T1 (Hitachi PAL-3A Chassis) 10/91 23 Philips KT3A-2 11 /91 43 Sharp 9C140 (Kriesler 37-104 & Similar Philips) 12/91 40 Philips GR100 TV Chassis Serviceman's Log 01/91 72 General GC-149 TV 02/91 76 Hanimex HTV7 TV; Hitachi VT33E VCR 03/91 26 Worn Heads On National NV370; Fisher FVH-P520 VCR 04/91 40 Toshiba C-2020 TV; Mitsubishi CT-2963 TV; Tandy CTV-2001 05/91 70 Sharp R2340E Microwave Oven 06/91 54 Samsung CB366H TV 07/91 44 National TC-1807 ; Sharp CX2048; Sharp DV-6384 08/91 60 General Electric TC53L2 (Hitachi NP6A-A Chassis) 09/91 40 Panasonic NVG-30A VCR; Hitachi CWP-131 TV 10/91 20 HMV B4803 TV; Philips K9, K11 11/91 40 Thomson TS5152 TV 12/91 40 Mitsubishi SC 6601 TV Computer Bits 01 /91 88 Hard Disc Failure: What To Do When Disaster Strikes 02/91 37 Why It Takes So Long To Turn On 03/91 62 Config.Sys, Ansi.Sys & All That Stuff 04/91 74 Playing With The Ansi.Sys File 05/9 1 76 Colouring Your PC World 06/91 74 How To Use The Keyboard Enhancers 07/91 88 Windows On A Brave New World 08/91 55 Installing Windows On Your PC 09/91 66 Swapfiles, Program Groups & Icons 10/91 42 Getting The PIF With Windows 11/91 66 Modifying The Windows INI Files 12/91 64 Windows : Unrecoverable Application Errors Amateur Radio 01/91 66 How Quartz Crystals Work 02/91 86 Oscillators - Which Type Suits Your Application? 03/91 70 A Universal Wideband RF Preamplifier 04/91 78 The Easytune FSK Indicator Projects to Build 01/91 22 Have Fun With The Fruit Machine 01/91 32 Fast Charger For Nicad Batteries 01/91 48 A Two-Tone Alarm Module 01 /91 80 Build A Bigger Laser 01 /91 92 LCD Readout For The Capacitance Meter 02/91 22 A Synthesised Stereo AM Tuner, Pt.1 02/91 46 Three Inverters For Fluorescent Lights 02/91 54 A Low-Cost Sinewave Oscillator 02/91 62 Fast Charger For Nicad Batteries 03/91 16 Remote Controller For Garage Doors, Pt.1 03/91 32 Transistor Beta Tester Mk.2 03/91 50 Synthesised AM Stereo Tuner, Pt.2 03/91 66 Multi-Purpose 1/0 Board For IBM PCs 04/91 22 SteamSound Simulator For Model Trains 04/91 30 Remote Controller For Garage Doors Pt.2 04/91 53 Simple 12/24V Light Chaser 05/91 79 AR2500 Multi-Mode Scanner Covers 500kHz-1500MHz 06/91 88 Active Filter Improves CW Reception 07/91 84 PEP Monitor Circuit For Transmitters & Transceivers 08/91 88 Ferrites - How They Work & Why They Are Used 09/91 78 How Glass-Mount Antennas Work 10/91 68 Optimising HF Antennas For Multihop Operation 11/91 53 Butld A Turnstile Antenna For Weather Satellite Reception 04/91 56 Synthesised AM Stereo Tuner Pt.3 05/91 24 Stereo Audio Expander 05/91 30 Build A DTMF Decoder 05/91 42 Fluorescent Light Simulator For Model Railways 05/91 58 13.5V 25A Power Supply For Transceivers, Pt.1 06/91 24 A Corner Refle9tor Antenna For UHF TV 06/91 36 Four-Channel Lighting Desk, Pt.1 06/91 64 13.5V 25A Power Supply For Transceivers, Pt.2 07/91 24 Battery Discharge Pacer For Electric Vehicles 07/91 36 Error Analyser For CD Players, Pt.1 07/91 62 Loudspeaker Protector For Stereo Amplifiers 07/91 68 Four-Channel Lighting Desk, Pt.2 08/91 16 Build A Digital Tachometer 08/91 24 Masthead Amplifier For TV & FM 08/91 38 PC Voice Recorder 08/91 66 Error Analyser For CD Players, Pt.2 09/91 16 Studio 3-55L 3-Way Loudspeaker System 09/91 28 Digital Altimeter For Gliders & Utlralights, Pt.1 09/91 58 Build A Fax/Modem For Your Computer 09/91 70 Ultrasonic Switch For Mains Appliances 10/91 12 Magnetic Field Strength Meter 10/91 32 SteamSound Simulator Mk.11 10/91 54 Build A Talking Voltmeter For Your PC, Pt.1 10/91 60 Digital Altimeter For Gliders & Ultralights, Pt.2 11 /91 8 Battery Charger For Solar Panels 11 /91 16 A Colour TV Pattern Generator, Pt.1 11/91 24 Flashing Alarm Light For Cars 11 /91 32 Digital Altimeter For Gljders & Ultralights, Pt.3 11 /91 60 Build A Talking Voltmeter For Your PC, Pt.2 11 /91 72 Error Analyser For CD Players, Pt.3 12/91 14 UHF TV Transmitter For VCRs 12/91 26 lnfrared Light Beam Relay 12/91 60 Solid State Laser Pointer 12/91 68 Colour TV Pattern Generator, Pt.2 05/91 05/91 06/91 06/91 12/91 12/91 12/91 12/91 06/91 07/91 07/91 08/91 08/91 08/91 Circuit Notebook 01 /91 86 Constant Volume Amplifier 01/91 86 Diode Test Adaptor For Multi meters 01/91 87 Precision Timer Goes To 46.6 Hours 02/91 20 Wide Range Inductance Meter 02/91 21 Mid-Frequency Tone Control 02/91 21 Coolant Level Alarm For Cars 03/91 46 Audio Filter For HF Receivers 03/91 46 3MHz Digital Frequency Counter 03/91 49 Direct Coupled Sniffer Probe 03/91 49 Simple Metal Detector 04/91 70 300Hz-3kHz Audio Filter 04/91 70 Simple IA Detector Checks Remote Controls 04/91 71 Bare-Bones Dual Power Supply 09/91 09/91 09/91 10/91 10/91 10/91 11 /91 11 /91 11 /91 11 /91 67 Lightning Distance Meter 67 Toy Car Motor Controller 32 5V Switchmode Power Supply 32 Discharger For Nicad Battery Packs 33 Shunt Controller For Solar Panels 80 3-Team Quiz Adjudicator 80 Analog Data Logging Via A PC's Parallel Port 36 Leading Zero Suppression For The Capacitance Meter 37 Automatic Controller For Sullage Pumps 37 Low Distortion Sinewave Oscillator 36 Soft Start For 240V Lamps 36 Voltage Regulator For Alarm Backup Battery 37 Simple Nicad Charger With 16Hour Timer 26 Dual Tracking Power Supply Uses Cheap Parts 26 DC Offset Canceller For Amplifiers 27 Battery Charging For Garage Door Controller 56 3-Way Quiz Game Uses Relays & Diodes 56 Low-Cost Variable Power Supply 57 Speed Sensitive Direction Switch 57 Power Supply For Portable Valve Radios 56 56 57 57 Budget Burglar Alarm System Expandable 3-Way Quiz Game Power Supply For Flash Gun 12 LED Voltmeter Remote Control 02/91 82 Galloping Ghost - The Evolution Of Proportional Control 03/91 74 The Development Of Digital Proportional Servos 04/91 86 How Pulse Code Modulation Decoders Were Developed 07/91 90 The Development Of Digital Proportional R/C Transmitters 08/91 33 Large Servo Amplifiers For Model Yachts 10/91 80 The Military Applications Of Radio-Controlled Aircraft 12/91 53 Motors For Electric Flight Models Notes & Errata 03/91 93 IA Remote Control Extender; September 1990 06/91 93 Garage Door Controller, March & April 1991 07/91 102 Stereo Audio Expander, May 1991 09/91 94 Stereo AM Tuner; Feb-April 1991 12/91 90 PC Voltmeter, Pt.1 ; October 1991 DECEMBER 1991 93 MARKET CENTRE Cash in your surplus gear. Advertise it here in Silicon Chip. ANTIQUE RADIO ANTIQUE RADIO restorations. Your one-stop radio repair shop. Specialising in restoring vintage radios including chassis rewiring, re-condensing, quality new parts, valves, valve sockets, speakers, power & audio transformers . Secondhand radio dials & parts for most brands & models. About 400 radios in stock for sale,.restoration & parts. Every restored wireless is covered by a 2year warranty on parts & labour. We restore damaged woodwork & cabinets & French polish (approx. 40 coats) . Vintage car radios available for sale or restoration . Repairs done on tape decks & 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 WEATHER FAX programs for IBM XT/ ATs *** "RADFAX2" $35 is a high reso- lution, shortwave weather fax, Morse & RTTY receiving program . Needs CGA, SSB HF radio & Radfax decoder. Also "RF2HERC", "RF2EGA" & "RF2VGA", same as RADFAX2 but suitable for 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 Qld. Phone (07) 358 2785. COMPONENTS SPECIALS available until end April 1992. MC14433 digital panel meter chip $15.00 (new stock) . MC45512 memory telephone dialler chip $10.00. 4001, 4011, 4071, 4081 $0.40 ea for 10 up. 4013, 4017, 4024, 4040 $0.80 ea in lots of 10 up. 7805, 7808, 78L05, 78L08 $0.40 ea. 1N914 $0.05 ea, 1N4004 $0.07 ea. 2114 static RAM r-------------------------, CLASSIFIED ADVERTISING RATES Advertising rates for this page: Classified ads - $7 .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 a separate sheet of paper & send it with this form & your cheque or credit card details to : Silicon Chip Classifieds, PO Box 139, Collaroy Beach, NSW 2097. Or fax the details to (02} 979 6503. Enclosed is my cheque/money order for $_ _ _ _ or please debit my D Bankcard D Visa Card 0 Master Card I I I I I I I I I SILICON CHIP IBM COMPATIBLE computer kits & accessories. Button spike protector $37.00. 6-socket power boards with surge/spike protection $49.00. Pack/ post $3.00. Send for a free price list. M.T.S. Electronics, PO Box 1013 Taree , NSW 2430. Phone (065) 53 1296. DIGITAL SPEEDO kit $50.00. Digital tacho with 10RPM resolution $49.00. Memory telephone dialler with single button dialling $30.00. 40kHz crystals $12.00. Hall effect sensors $4.00. Certified P&P $5.00. CTOAN Electronics, PO Box 33, Condell Park, NSW 2200. Phone (02) 708 3763. PATCH PLUGS:¼-inch T-R-S. New. 25 for $15 posted anywhere in Oz. Bulk prices available. Phone Greig (02) 799 3951 (6-10pm). GARAGE DOOR REMOTE control kit: see SILICON CHIP March/April 1991 . For orders received before the end of January 1992, we are offering one complete receiver kit and one ready made transmitter for the special price of $94. Oatley Electronics, PO Box 89, Oatley, NSW 2223. Phone (02) 579 4985. LASER DIODE HEAD BARGAIN: we have a small quantity of 3mW laser x I Card No . I I Signature_ __ _ __ __ _ _ _ Card expiry date_ _~ /_ __ I I Name _ _ _ __ _ _ _ _ _ __ _ _ _ _ _ _ _ _ _ __ I I Street _ _ __ __ __ _ _ _ _ _ __ _ _ _ _ _ _ __ I I Suburb/town _ _ __ _ __ _ __ _ Postcode_ _ _ __ _ L _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ JI 94 chips $1.50 ea, data available. P&P on components $4.00 up to order value of $200.00 . Ring for postage rates on higher order values. CTOAN Electronics, PO Box 33, Condell Park, NSW 2200. Phone (02) 708 3763. CORNER REFLECTOR ANTENNA KIT The original SILICON CHIP design. Outperforms commercial units at a fraction of the cost. Comes complete with all parts, cut & predrilled. Easy to assemble in under 1 hour. $65, ,ncluding postage anywhere in Australia. Send cheque/money order to: BDK Audio, 46 Calderwood Rd, Landsborough , Old 4550. Phone (074) 94 1928 r COMPUTER BARGAINS Systems: 286-16MHz CPU $1290.00 386SX-16MHz CPU $1545.00 All systems AMI BIOS, 1Mb RAM, 1.2Mb or 1.44Mb FDD, 42Mb HDD, 2 Serial & 1 Parallel port, SVGA monitor 0.28, 1024 x 768, 512K VGA card, desktop case, 200W PS, mouse with system only $20.00. Japanese floppy drives: 1.2Mb $100.00, 1.44Mb $95. 3-Button mouse with pad and adaptor $37. Mini tower case with 200W PS, 4 doors $135.00. 1Mb Trident VGA card incl. RAM $159.00. All prices incl. sales tax. Cheques & credit cards accepted. For comprehensive price list and oraers, contact: BDK Audio, 46 Calderwood Rd, Landsborough 4550. Phone/fax (074) 94 1928. Prices at October 1, 1991 SIMM 1MBx9 100ns sons 1MBx8 100ns 80ns 4MBx9 80ns 256 X 9 sons (For SIP add $1) DRAM-DIP 1MBx1 80ns 256 X 4 100ns 80ns 120ns 41256 100ns 80ns \.. r TRANSFORMER REWINDS TRANSFORMER REWINDS Reply Paid No.2, PO Box 438, Singleton, NSW 2330. Ph: (065) 761291. Fax: (065) 76 1003. LCD MODULES: when this magazine is printed, we will have in stock a range of brand new high-quality liquid crystal display (LCD) modules, at a small fraction of their expected prices . For example, we will have a 20-character 2-line (20 x 2) display with backlighting _for around $30. All modules will come with information and we should have a backlighting inverter kit for the displays available. Oatley Electronics, PO Box 89, Oatley, 2223. Phone (02) 579 4985. XT/ AT HANDBOOK by Choisser & Foster. Pocket size 92 pages. For Engineers & Programmers, & other serious PC/XT & PC/AT users. A collection of 58.00 55.00 48.00 56.00 240.00 16.00 6.00 5.90 6.00 1.80 2.00 2.20 COPROCESSORS 80387-DX To 33 80387-SX 16 & 20 80287 To 12MHz 80287 Over 12 250.00 157.00 100.00 147.00 FLOPPY DRIVES 3.5 Panasonic 1.44 3.5 Teac 1.44 5.25 Panasonic 1.2 80.00 86.00 92.00 EXPANSION CARDS LS 866N 32Mb OK 240.00 AST RAM plus 8Mb 350.00 BOCA AT plus 8Mb 250.00 SPECIALS Sun SLC Sharp 6220 Sharp 8081 PS/2(ALL) PS/2(ALL) Mac FX/NIX Laser Printers 4Mb 1Mb 1Mb 2Mb 4Mb 4Mb 2Mb 300.00 180.00 100.00 168.00 305.00 250.00 206.00 SOCKETS Simm Sockets 30 x 1 Vert 1.70 Simm Sockets 30 x 2 Ang 3.50 Simm Sockets 30 x 2 Vert 3.20 Sales Tax 20%. Overnight Delivery. Credit Cards Welcome 1st Floor, 100 Yarrara Road, Pennant Hills, NSW 2120. Tel (02) 980 6988 Fax (02) 980 6991 ~ PELHAM ALL TYPES OF TRANSFORMER REWINDS diode heads which were originally designed for use in very small pen-sized laser pointers. Dimensions: 11 mm diameter x 22mm long. They are designed to be powered from two small AAA or N type alkaline batteries. Alternative supplies can be used but a constant current source must be added (see suitable circuit in this issue of SILICON CHIP}. The heads are offered at a clearance price of $150. Oatley Electronics, PO Box 89, Oatley, NSW 2223. Phone (02) 579 4985. "I MEMORY EXPANSION UNIDEN SCANNERS DON'T PAV MORE! 50XL RRP $299.95. Our price $211 10 memories, Lo-Hi VHF, UHF 1OOXL T RRP $449.95. Our price $409 100 memories, Lo-Hi VHF, Air, UHF 200XL T RRP $549.95. Our Price $477 200 memories, Lo-Hi VHF, Air, UHF, 800 MHz All prices include delivery. Phone anytime today! (03) 883 9535; Fax (03) 432 0716 TopCom Communications PO Box 336, Greensborough, Vic 3088. ~ \.. KIT REPAIRS Kits repaired from all m"agazines. Switchmode power supplies repaired, design work from start to finish computer software consultancy. Ring anytime 9am-9pm Mon-Sun. EEM Electronics, 10 Bouverie Place, Epping, Vic. 3076 Phone (03) 401 1393 hardware & software facts & data on the PC compatible family & its operating system. Latest Edition. This is the one advertised by Annabooks in US magazines Byte, Dr Dobb's Journal, etc. $20 including postage. 5 or more $15 each. Don McKenzie, 29 Ellesmere Crescent, tu llamarine 3043. SOLAR PANELS, wind generators, batteries, inverters, etc. Our 50-page Solar Engineering catalog is the definitive statement on equipment and price! Send $15 to Solar Technology, PO Box LEARN ELECTRONICS WITH UCANDO VIDEOS AC-DC power supplies, amplifiers, integrated circuits, oscillators. Average one hour each. $A48.00 each. Also build electronic kits for learning experience. Mastercard & Visa accepted. Electronics Assembly Co, PO Box 21191, Edgeware, Christchurch, New Zealand. Phone 3-795-570 FIX-A-KIT KIT REPAIR & CONSTRUCTION 3 MONTHS WARRANTY ON REPAIRS 12 MONTHS WARRANTY ON CONSTRUCTION TECHNICAL ASSISTANCE HYCAL ELECTRONICS Design, Manufacture & Repair of Electronic Equipment (02) 633 5477 1129, Esperance 6450. Phone (090) 71 3719. OSCILLOSCOPE: 35MHz, dual trace, dual timebase, Leader LB0-524. As new, private sale, $800. Phone (02) 217 0232 BH Seaforth. PC TALKING VOLTMETER software. For project published in SILICON CHIP, Oct/Nov 1991. Plugs into the printer port of any IBM PC/XT/AT/386 or compatible. Displays voltages up to ±128V on screen, takes voltage samples over DECEMBER1991 95 Market Centre - continued from page 95 Advertising Index Altronics .... .. .. .... .................. . 22-25 Antique Radio Restorations ..... . 94 Av-Comm .. .. ... ..... .. ..... .. ......... ... . 77 Back Issues .. ..... .... ..... .. ... .. . 36,37 BOK Audio .......... ............ ... .. . 94,95 David Reid Electronics ...... .. 2,3,73 Dick Smith Electronics ... .. ... . 10-12 EEM Electronics .. .... .... .... ......... 95 SUSIES COMPUTERS Electronic Components Shop ... 20 36 Regent Street, Kensington (08) 364 0902. 75 Main South Rd, O'Halloran Hill (08) 322 4299. Electronic World ................... ..... 85 Electronics Assembly Co . ........ . 95 Elmeasco ......... .... ............... .... IBC time, 8-bit accuracy to within 1%, combines with the .PCVOICE RECORDER to give a talking voltmeter. Available on 5¼inch 360Kb disc plus documentation and instructions for $35 plus $3pp. Also available PCVOICE RECORDER software - turn your computer into an audio recorder $25 + $3pp (VGA/EGA/CGA/ MONO) . MS-DOS required. Send your cheque or money order to Darren Yates, PO Box 134, French 's Forest NSW 2086. Emona Instruments ...... ... .. ......... . 9 WANTED Geoff Wood Electronics ............ 31 WANTED: MANUAL; Handbook for Harbuch Electronics ... .. ... .. .. ..... . 87 Mullard Valve Tester, CT80/1/3. Phone (045) 761410 . Hycal Instruments ... ..... .. ..... ...... 95 CP/M PROGRAMS wanted to buy for Jaycar Electronics ................ 45-52 Little Big Board Processor with 8-inch double sided drives. Call Bill Collison (08) 232 1373. SC J.V. Tuners ....... ....... .. ...... ..... ... .. 43 r------------ ---------- ---, SILICON CHIP BINDERS X Protect your valuable issues with a special binder from SILICON CHIP. Our binders feature heavy board covers, are made from a distinctive two-tone green vinyl, and have the SILICON CHIP logo printed in gold-coloured lettering on the spine and front cover. They hold up to 14 issues and will look great on your bookshelf. Price: $A 11 .95 + $A3 p&p or buy a subscription and get a discount on the first binder (see the subscription order form in this issue) . lcom Australia .. .. ................... OBC Kalex ....... .. .. .. .. .. ................. ....... 86 Oatley Electronics ... ... .......... 63,95 PC Marketplace .... ... .. ........... .. .. 71 Pelham ..... .. ........................ ....... 95 Philips ... ... .. ............. ... .... .. ....... IFC Preston Electronics ..... .............. 87 RCS Radio ........ .......... .............. 85 Resurrection Radio ... ...... .......... 35 Rod Irving Electronics .... ... ... 38,39 58,59,82,83 Subscriptions ............... ..... .... .... 91 Susies Computers .... .. ..... ... .... .. 96 Yes! Please send me _ _ _ _ SILICON CHIP binder(s) at $A11.95 plus $A3 p&p each (NZ $A6 p&p). Enclosed is my cheque/money order for $_ _ _ _ or please debit my O Bankcard O Visa Card O Master Card Transformer Rewinds .... ..... .... .. . 95 PC Boards Printed circuit boards for SILICON CHIP projects are made by: Card No. Signature_ __ __ _ _ _ __ __ Card expiry date_ _~/_ __ Name _ _ _ _ __ _ __ _ _ _ _ _ _ __ _ __ __ _ _ Street _ __ _ _ __ _ _ _ __ _ _ __ _ _ _ _ _ _ __ Suburb/town _ _ _ __ _ _ _ __ _ _ Postcode_ __ __ _ Silicon Chip Publications, PO Box 139, Collaroy Beach, NSW 2097, Australia. Fax: (02) 979 6503. L _______ __________________ J 96 TopCom Communications .. .. ..... 95 SILICON CHIP • Electron ic Toy Services, 2/111 Glynville Drive, Hackham West, SA 5163. Phone (08) 382 8919. • Jemal Products, 5 Forge St, Welshpool, WA 6106. Phone (09) 350 5555. • Marday Services, PO Box 19-189, Avondale, Auckland, NZ. Phone 88 5730. • RCS Radio Pty Ltd, 651 Forest Rd , Bexley, NSW 2207. Phone (02) 587 3491. Eight Advanced Features Make Metrix ASYC ®Series Safest Check these 8 important safety features only found in the Metrix ASYC Series • Advanced housing design has screw-free assembly and is waterproof through a patented low-pressure, double seal design. • Housing is moulded in VO-grade self-extinguishing material • VDE!GS certificated to international standards • Safe flexible test leads with shrouded plugs and large cross section conductors to reduce heating during high current measurements • Battery and fuse compartment are fully sealed, both internally and externally using a patented double seal design • Access to battery and fuse is only possible after removing test leads • SECUR'X lead locking device prevents leads from being disconnected accidentally • Safety alarm gives an audible warning if measured signal exceeds specified range (10A ac ordc, 750Vac, 1000Vdc) Quick Selection Guide Model MX20 MX50 MX51 MX51 EX MX52 MX52S A multimeter doesn't just get used in the laboratory. It is a tool that is relied on to work accurately in difficult conditions - without endangering the user. ITT Instruments have analyzed the crucial elements in a multimeter and developed technical solutions for each of them . The result is ASYC®, Advanced Safety Concept, a synonym for safety and performance. It is your guarantee of safety and technological perfection. ----=-- ASYC 111..1:::.&.1.:.1 <at>[Q] U Advanced Safety Concept BLMBASCO NEW SOUTH WALES Tel (02) 736 2888 VICTORIA Tel (03) 879 2322 QUEENSLAND Tel (07) 875 1444 Fax : (02) 736 3005 Fax : (03) 870 8972 Fax : (07) 277 3753 Basic Accuracy 0.5% 0.5% Bargraph Zoom Mode1 Zero Mode 2 Live Trend Memory3 Logic Function Min/Max Recording Store 5 readings Relative Mode RMS Conversion Frequency dB level High Accuracy(0.1%) 4-20mA Intrinsic Safety EEx ib IIC T6 HBC fuse protection ••• •• • • 0.1 % 0.1% 0.1 % • •• • • ••• •• •• • ••• •• •• • ••• •• ••• •• • 0.1 % •• ••• ••• •• •• • 1. Zoom mode gives Sx magn1f1cat1on 250 seg ment sl1d1ng scale bargraph display 2. Zero mode functions as centre-zero meter for ra pid polarity change measurements and zeroing 3. Live Trend mode digital display shows stored value, bargraph shows absolute value (ie simultaneous display of current and stored values) Instruments Ply.Ltd. SOUTH AUSTRALIA W. AUSTRALIA Tel : (08) 344 9000 Tel: (09) 470 1855 Fax : (08) 269 6411 Fax: (09) 470 3173 READER INFO NO. 22