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The Snowy Mountains Hydro Scheme ~ - ~ AUSTRALIA'S DYNAMIC . ELECTRONIC? MAGAZINE~ .:.a- SERVICING - VINTAGE RADIO - COMPUTERS - AMATEUR RADIO - PROJECTS TO BUILD attery discharge seer for • ·.. ric CHASSIS PUNCH SET with TAPERED REAMER * 10 pcs. screw type punching tool set. * Size: 16, 18, 20, 25, 30mm. * Reamer: 3 to 12mm. * Made in Japan. was $7l95 -El!i * Detects Propane, 6utone and Methane gases. * Inbuilt visual and oudlable olorm. * N.O./N.C. output for alarm systems. * 12 volt DC operation. ATS-808 SANGEAN * FM/LW/MW/SW $199.00 save $10000 LIMITED STOCKS A-3000 Remote Control * ~ . ~ Transmitter Unit * * * N.0./N.C. relay output up to 5 amps. Receiver operating voltage: 12V D.C. Complete with two remote keys. Operating distance: 10 meters. ..,,, -: --~::-:.~~-:-- _: Normally $299.00 Now$259.00 12volt 6.5Ah Gel Cell Battery (I ual-tilller EL ECT RO NI C PLUS CLOCK A 24 hour dual/timer/ clock with; 2 countdown timers, 2 preset memories, count-up timer and clock. Oisplays Hours, Minutes and Seconds. •··•. .r,.,, . Save $100.00 SHORT WAVE RECEIVER .._;, $69.95 ' Se/lout Price -~:--~-[ $99.95 NowOnlg . * 100/200/300/400 DP/ * 45 Memories. Norma/lg •'..•. . * 105mm scan width $499.00 JIC-67BN (LPG,LNG) GAS LEAKAGE DETECTOR . ,. HS-3000 HANDY SCANNER For uses with: DESK-TOP PUBLISHING WORD PROCESSING CAD APPLICATIONS DATA BASE Special Introductory Price save $22.00 iJ• • Dual Diversity Wireless Microphone System. 1816MHz Butane Pencil Torch The ·sutane Pencil Torch· will melt solder. silver solder, small brazing rod, glass tubing, etc. save$40.00 Engraving Pen * Uses two "AA" batteries. NOW $89.95 was $109.95 Bask MOTOROLA ondthe 6800 M68000 FAMILY REFERENCE DATA BOOK Microprocessors Motorola Doto Book (not lncludod} •· : ; was $54.95 t~~:(\:\ Now$39.95 ~- only $19.95 only $3.95 Nit:e-Wot:ch PIR 40 pcs. UNIVERSAL TOOL KIT * Coverage: 90°<at> 15 meters. * Timing and Sensitivity Adjustment. * Lights con be operated manually. "Keep one In the boot of the car or for the work-shop, complete In o handy carry case" save $15.00 Motion 01Jt1J<fo1 11/t/J Flood light Kit only $7.00 ,, \ only $7.00 MOTORAD TL-301 TIMING LIGHT with DIRECT READING ADVANCE SCALE * Test timing on all 12 volt conventional and electrontc systems, 4, 6 or 8 cyllnch,rs, Including rotary motorJ. (flood llghts not ln<lud<1d) normally $39. 95 was $99.95 Now $69. 95 Now 129.95 was $/JO.OD Now 169. 95 Fa5t,, Efficient,, Reliable Service. Multi-lingual Pocket • mr-as.lc:::atc:>r * Instant word conversion of, ENGLISH, FRENCH, GERMAN, SPANISH, ITALIAN. 1400 words per language. * No,ISP,PS 22 pcs. T -Bar Socket Contains: *1pc. T-Bar driver handle. *9pcs. Metric Skis. (5,6,7,8,9,10, 11,12,13mm). *3pcs. Phillips Bits (#1,#2,#3). *3pcs. Posi-Drive Bits (#1,#2,#3). *5pcs. Slotted Bits (3,4,5,6,8mm). S<arf to 6 r RCA Videoleod * Scott p l ug to:· 2 x RCA plugs (video In / out) 4 x RCA plugs (audio Jn / out) Nowl7.95 This Is not a mlsta/rs P I ~ C:,etec:;tc:,r * Fixed or Portable Alarm. * Welcomes visitors and deters intruders. * Ideal security for around the home, shop or office. Battery operated. 10 mt range <at> 130° * * * * * * * * * * onlgl/9.95 COMPUTER DISKETTES * 5.25" D.S.D.D. PKT /10 $5.00 PKT /10 $10.00 KASPAROV Pocket-Plus CHESS COMPUTER * NYLON Quo1tzGocx CALIPERS Movement 8 levels of _ploy * 3.5" D.S.D.D. PKT /10 $9.50 * 3.5" D.S.H.D. PKT /10 $23.50 onlg S/3.50 GREAT VALUE I I Convert your Oscilloscope to a SPECTRUM MONITOR with o bandwidth of 100MHz The SPECTRUM PROBE Is a low cost 100MHz Spectrum Anolyzer In 0 hondheld probe. * Use It as a sensitive RF detector. * locate readfoted EMI sources. * Check your Rf signal generator. t ·'- * Check for stage 90lns In ampllflers. onfvlJ9,95 _..\. Doto Switch Box ~ ~ 4wag VGA and · _Kegboord switch box * 4 way VGA (DB-915) monitor sockets. * 4 way 8 pin mini DIN keyboard sockets * 1 in 4 out, or 4 in 1 out operation. * Ideal for 4 terminals to one computer. only only S3BS.00 I gear warranty 1v ,PPrlt11/ and Bit Set Contains: 1pc. T-Bar driver handle. 3pcs. Phillips Bits (•1,#2,•3). 4pcs. Slotted Bits (3-4,6 -8,8 -10,10-12). 4pcs. Allen Bits (3/32,1 / 8,5 / 32,3/16) . 2pcs. Square Bits (R1,R2). 6pcs. Torx Bits (T-10,15,20,25,30,40). 9pcs. Metric Skis. (5,6,7,8,9,10,11,12,13mm). 9pcs. SAE Skts. (3/16,7/32,1/4,9 / 32,5/16, 11/32,3/8,7 /16,1/2"). 1pc. 1/ 4 • socket adaptor. 1pc. bit adaptor. 1pc. 90 deg. adaptor. * * 5.25" D.S.H.D. COMPACT Door Entry * 10 mt. reel * for a total of 85 commands. indicating function in use and clock. Alarm. can automatically turn ON/ OFF any one of five components. Countdown timer. can automatically turn ON/ OFF any one of five components. 8 K memory. 41 pcs. T -Bar Driver No,164.95 normally $29.95 of the stuff I The TELE-ART RCt00 Universal Remote Control Unit ·can replace the infra -red remote controls of up to five audio/video components by simply learning and then mimicking their remote control command codes. This eliminates the confusion of which remote control to use and does away with the clutter of too many remote controls. * LCD display -~ . . .,;~ We've got reels RC-/00 Universal Remote * * * SW/C8 ... 15-30 MHz. No,IPP,PP * Can memorize up lo 17 commands per component, onlgl9.95 DIAL CORD • save $30.00 Driver and Bit Set * * * * FM ...88-100 MHz. * TV A/VHF ... 55-100 MHZ. * TV 8/VHF ... 175-218 MHZ. * Alr/Morlno .. 108-175 MHz. * Rodlo direction finder . * ond more Ill was $/49.00 was $B9.95 save $20.00 onlg $9.90 * AM ...531-1605 KHz. * HF ... 2-6 MHz. * Wolk test indicator. Now onfv 149,95 * D8-25 mole to CENTRONIC mole * 1.8 _meters long. PRO IR!Y/'-6!1<at> SERIES MULTIBAND RECEIVER <at> normally $69.95 iBM Printer Cable PIR-8612 PIR Detector * Single shot or Pulse count circuit. * Power source: 10.5-16 volt DC. * N.C. contact switch. * N.<;,. tamper switch. * 84 12 meter range. NEC RELAYS * MR72C· 6volt DPDT 5 omp. 70 ohm coll. * MR71C-5volt SPOT 10 omp. 50ohmcoll . • High Voltage Cops * 100 uf 250V DC RB electro. * 220 uf 250V DC RB electro. All one price 00 One prict1 $4 110. $2.95 each David Reid VALVES * 6L6 * EL34 * 12AX7 * 12AT7 * 6BQ5 * EF86 $14.50 $14.50 $8.45 $8.45 59;95 59.95 189.95 RS232 Coblt1s * DB - 25 male 5 mt. only * D6 - 25 mole 5 mt. only * DB - 25 ma le * 2 mt. only 06-25 male 2 mt. only to 0B - 25 539.95 to DB - 25 539.95 lo 0B- 25 519.95 to 0B -25 519.95. molo femole 10 volt AC Power Pack * * 10 volt AC <at>I 1 amp. 2.1mm DC piug fitted. male onlg $/9.95 female 127 York St. SYDNEY 2000 PH: (02) 2671385 Electronics P.O. Box QI03, SYDNEY 2000 FAX: (02) 2618905 (~ ~-·-~--] Qi:/:,;:~ :~ SAME DAY MAILORDER DESPATCH* Post ond Packing SS • 525 ., .... ,. $4.00 $26 • $50 ...... $6.00 $51 • $100 ...... $7.00 $101 - 5499 .... $9.00 5500 • ..... ....... FREE ! . ~ : ~ ' July 1991 FEATURES 6 How Install Multiple TV Outlets, Pt.2 by Jim Lawler BASED ON A FEW low-cost ICs, this simple project can indicate the percentage ampere-hour capacity used or remaining in u rechargeable battery. It can also be used us a "fuel" pacer to obtain maximum performance from an electric racing car. Turn to page 24. Couplers, signal losses & boosters 18 Tuning In To Satellite TV, Pt.2 by Garry Cratt Hardware requirements for C & Ku-band reception 96 The Story Of Electrical Energy, Pt.11 by Bryan Maher The Snowy Mountains Hydro Electric Scheme PROJECTS TO BUILD 24 Battery Discharge Pacer For Electric Vehicles by Dieter Kuenne Can be used as a "fuel" pacer or to show charge remaining 36 Error Analyser For CD Players, Pt.1 by Stephen McBride Counts interpolations & dropouts 62 Loudspeaker Protector For Stereo Amplifiers by Bob Flynn Protects your speakers from amplifier overdrive or failure BUILD THIS CD ERROR analyser & put an end to the myths of green pens, special feet & other gimmicks. The device connects to your CD player & shows the number of interpolations & dropouts. See page 36. 68 Four-Channel Lighting Desk, Pt.2 by John Clarke Full construction & testing details SPECIAL COLUMNS 14 Vintage Radio by John Hill Some simple repair techniques 44 Serviceman's Log by the TV Serviceman Bits & pieces - odd & ends 84 Amateur Radio by Garry Cratt PEP monitor circuit for transmitters & transceivers 88 Computer Bits by Jennifer Bonnitcha Windows on a brave new world 90 Remote Control by Bob Young The development of digital proportional R/C transmitters DEPARTMENTS 3 Publisher's Letter 4 Mailbag 57 Subscription Page 59 Product Showcase 78 Back Issues 2 SILICON CHIP 80 Circuit Notebook 101 Ask Silicon Chip 102 Notes & Errata 103 Market Centre 104 Advertising Index LAST MONTH, we gave you the circuit details & specifications of our new 4-chunnel lighting desk. This month, we show you how to build it - see page 68. Change of Address Please note: during June 1991, we changed premises. Our offices are now at Unit 1a/77-79 Bassett Street, Mona Vale, NSW 2103. Our postal address and phone numbers remain the same as before. Publisher & Editor-in-Chief PUBLISHER'S LETTER Leo Simpson, B.Bus. Editor Greg Swain, B.Sc.(Hons.) Technical Staff John Clarke, B.E.(Elec.) Robert Flynn Darren Yates Reader Services Ann Jenkinson Advertising Manager Paul Buchtmann (02) 979 5644 Mobile: (018) 28 5532 Regular Contributors There's an electric vehicle in your future Those who read Gerry Nolan's article on electric vehicles in last month's issue may be forgiven for thinking that it would be the last article we would have on that subject for some time. However, we expect that electric vehicles will continue to become more topical in the future and we also expect to have more practical articles on this subject. In fact, this very month we have just such an article - the Battery Pacer article beginning on page 24. Gerry Nolan foresaw in his February 1991 article that a battery capacity meter, a sort of electric charge gauge, would be a reality in the near future. He could not have known, when he wrote those words, just how near that would be. Already we have seen such a product previewed (April 1991, page 81) and now we present a build-it-yourself version, designed by contributor Dieter Kuenne. So the future draws closer. A lot of people are quite sceptical about whether we will ever see electric vehicles in large numbers on the roads. They cite the failure of electric vehicles to be really practical in the past and they also point to the great load that electric vehicles, if they were produced in large numbers, would place on the nation's generating capacity. And they go on to point to the inevitable greenhouse effect of the additional generating capacity that would be required. In fact, if electric vehicles did become very successful, we would be using less energy than we are now and so the greenhouse effect would be less. We would also be conserving precious petroleum reserves which will run out long before the world's coal reserves. And we should not forget the considerable energy contribution that solar power could make to electric vehicles. As time goes on, the arguments for electric vehicles will become ever more compelling. And lest I seem like an out-and-out protagonist for electric vehicles, we should also not forget that conventional petrol-powered vehicles still have considerable potential improvements in fuel economy. It seems entirely possible that motor vehicles of the future could achieve fuel economy as high as 3 litres/lO0km (100 mpg) or higher. Sound fantastic? It's not really. Consider that large interstate semi-trailers already achieve 45 litres/lO0km (6 mpg) or better and they're pulling 38 tonnes or more at over lO0km/h. With that in mind, why couldn't a one tonne vehicle obtain fuel economy of 3 litres/100km? Even sp, the chances are high that you will be driving an electric vehicle in the future and that day may not be far off. Leo Simpson Brendan Akhurst Jennifer Bonnitcha, B.A. Garry Cratt, VK2YBX 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. All material copyright©. No part of this publication may be reproduced without prior written consent of the publisher. Printing: Magazine Printers Pty Ltd, Alexandria, NSW; Macquarie Print, Dubbo, NSW. Distribution: Network Distribution Company. Subscription rates: $42 per year in Australia. For overseas rates, refer to 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 JULY1991 3 MAILBAG Customer service begets customer loyalty With reference to your "Publisher's Letter" column regarding customer service, in the April issue, I agree wholeheartedly with your sentiments on minimum cash sale values. It would appear to me that any turnover, be it $1.00 or $1000, would increase the net result of the company. Most companies can, and most probably do, calculate the cost of servicing their customers to the cent. I can see that a credit sale of $1.00 would show a loss, possibly even as high as $20.00, to the company. However, any cash sale is profitable. Most overheads are fixed and therefore need to be paid for regardless of the amount of activity at the front counter. Surely it is better to turn over $1.00 than have the staff, lights, insurance, advertising, etc doing nothing but look pretty. It may only contribute a cent towards each area of cost, but that's a cent less to find at the end of each month. A short tale to illustrate. I required a piece of aluminium sheet to complete an antenna project. On a square metre rate, it would have cost approximately $7.50. The charge to cut this out of an already cut sheet was to be $15.00; ie, an all up cost of $22.50. On querying this charge, it was explained that depreciation of the guillotine, blade wear, electricity, wastage and his time added up to almost $14.96 per cut and he could even show me a breakdown of the figures from his accountant. I pointed out that his time was already costed out in the price of the item, as was the depreciation, electricity and blade wear. The wastage, and I concede there would be some (possibly as high as 10% depending on the sizes required by various customers), could be covered by a small surcharge. In the order of 10-15% would be reasonable, not 200%. I was browsing for 10 minutes and discussing the above for 10 minutes, and was the only customer in the store during that time. I left without my aluminium and 4 SILICON CHIP tried another store. "No problem, what size?", was the answer at my next stop. "How much?" - "$7.90"; "Any cutting charge?"; "No!" I bought! The place was full - I wonder why? My next antenna project required $215. 00 worth of aluminium tube and plate. Guess where I got it? Even small customers buy a large quantity now and again. If the quality is much the same, then service is the criteria that gets and keeps customers. I have often wondered whether one $1000 credit sale (paid for in 30 days? ... sometimes) is better than one hundred $10.00 sales paid in cash. Now for a couple of observations on your magazine. It is my only regular monthly purchase, apart from an amateur radio µiagazine. I like the trains, power stations, electric cars, Remote Control, Amateur Radio, Serviceman's Log, Computer Bits, Vintage Radio and the projects. Even though I don't understand as much as I would like, I find the format and writing style of your columnists and feature writers entertaining and informative. I have found yours to be the only magazine I can be guaranteed of finding at least one article of interest (usually many more). It sits on the bookshelf with Time , National Geographic and Australian Geographic as a general reading and study guide for the whole family. Now if you only covered ancient Greece and cricket! Thank you in anticipation of many years of pleasure. R. M. Bingham, VK4KCM, D' Aguilar, Qld. Combiners, splitters and VNG time signals Firstly, congratulations on the standard of your magazine, which I have taken since issue No.1. I have two specific reasons for writing at this time. Jim Lawler's article in the May issue on installing multiple TV outlets contains an almost "throw-away" line when speaking of combining the output of a VCR with that of an antenna, where he says "this is done in a SILICON CHIP, PO Box 139, Collaroy Beach 2097. 'combiner' in reality a 2-way splitter used back to front" . As one who likes to "roll his own", there is no real problem in devising a splitter to serve two or more loads, but it seems to me that, strictly speaking, a "combiner" which combines two or more sources, is something else. I have searched the literature available to me and can find nothing on the design of such a device, or at least the reasoning which supports the use of a "splitter back to front". Do you think that this could be covered somewhere in your magazine? The other matter is the decoding of VNG time signals . I am a strong supporter of the concept of Australia maintaining its own time signal station and the VNG Users Consortium is to be congratulated on its successful efforts in doing this. However, it is a pity that the minutes and hours are not identified in a readily recognisable way (adding a voice announcement would be beyond the means of the consortium). As a CW enthusiast capable of moderate speeds, I have tried decoding the signals provided but find that the difference between the long and short pulses is too small for reliable mental decoding. To get to the point (at last), I think there could be a good deal of interest in a VNG decoder and I wonder if I could interest you in developing such a beastie? K. T. Andrew, Ryde, NSW. Upside down Yagi will malfunction Without a doubt, SILICON CHIP is one of the best electronics magazines. However, on page 6 of the May 1991 issue, Jhe "Yagi" VHF/UHF antenna is shown installed upside down. This doesn't really affect the quality of signal but after 6-12 months you'll find that the terminals are beginning to rust on the balun box. This is because the balun box has pilot holes and , if the antenna is installed upside down, it lets the rain water in. The instructions are explicit, yet DURING JULY - SEPTEMBER and only while stocks last hundreds of people install it in this way and find they have problems shortly afterwards which undoubtedly keeps me in business. John Coppola, The TV Antenna Doctor, Geelong, Vic. Telephone equipment needs approval I am writing to you concerning articles in your magazine which give instructions on the construction of customer equipment for use on a telecommunications network. The most receHt of these is an article on the construction of a DTMF Decoder in the May 1991 issue. The ·Telecommunications Act 1989 requires that only customer equipment which has an AusTEL permit in force is permitted to be connected to a telecommunications network. Your articles fail to mention this and the article itself openly enr:ourages readers who may wish to build the customer equipment, to connect it to a network. As there is no permit in force for the equipment, readers who constructed the unit would be committing an offence if they then connected the customer equipment to a network. The permit process is in force to ensure that customer equipment is of a standard so as not to affect the interoperability of the network and to ensure the safety of the network and of persons. It is requested that you consider your magazine 's position on these articles in light of what has been st~ted earlier and advise as to what course of action it is proposed to take. At the very least it is considered that your article should warn of the risks of connecting non-permitted customer equipment to a network. J. Helm, Investigations Officer, AusTEL, Melbourne, Vic. Pay TV can be afforded I really must query the last paragraph of your May 1991 editorial. On what basis do you conclude that "most people don't want, don't need and can't afford pay TV"? Even "can't afford" is, to me, highly questionable when one considers the big brass which so many people squander on cars and backyard swimming pools, to give just two examples. Increase in demartd causes increased production and lower unit costs. This country has had pay TV for years and still has it. Remember Sky Channel? The really bad aspect of our commercial TV network is that we all pay for it, whether we use it or not. The major political parties will happily blow 20 million or more of our tax dollars in just one Federal election campaign; this is not even a fleabite compared with the mammoth amount spent in advertising each year on commercial TV. Who pays? We do! So do you! I reckon that you could knock a third off the price of everything advertised on TV if those ads didn't exist. The commercial networks run on a "take what you get" approach, whereas pay TV is more "get what you want" without having to go out and rent it. VCRs do offer ultimate user-determined convenience but I cannot be bothered time-recording anything from commercial TV because anything shown is broken into meaningless sections by torrents of adverts, often fitted in at the expense of the program. Time-record for time-shift viewing from an ad-free channel which pay TV should be, and which Sky Channel is not, would be a reasonable exercise. Why can't the country afford it? The dishes and receivers are local products, even if the LNC is not. Market penetration would be determined by we the people, not by a bunch of · bungling idiots who make mincemeat of every communications issue in which they stick their big feet. Why the pay TV issue is under the control of politicians is beyond me. Why can't we decide for ourselves in the free world? We have a perfectly good satellite system which already does the job without the need for an optical-fibre network. In fact, you would need enough optical fibre to stretch from here to Pluto to interconnect all centres and cover every residence in the country - at hideous expense. Aussat exists and can do the job. J. Kentwell, VK2XBR, Springwood, NSW. WINTER SPECIALS INFRA RED NIGHT VIEWER Similar to E.A project (May and Sept. 90), but is smaller when assembled. Yes this kit includes an adjustable high quality long range mil spec lens with a built in IR filter as well as a high quality eyepiece. The tubes are NEW IR types (BWB 258). The lenses and eyepieces were removed from NEW mil spec night vision equipment and guaranteed not to have any blemishes. You would normally pay over $2000 for a viewer which uses a similar tube and optics! The lens, tube, eyepiece, are only part of the complete kit supplied. The Price of this bargain???: $ ... 299. 00 What is in the kit: A BWB258 tube, an adjustable long range objective lens, an adjustable eyepiece, sufficient plastics for the case, a 775mm round IR filter, an electronics kit as per the E,A May 90 article, and the instructions .... Kit No. IRNW5 MORE BARGAINS?: Check our adds in the "MARKET CENTRE" of this ma azlne. 2mW PHILIPS LASER HEAD WITH UNIVERSAL 12V POWER SUPPLY 'Uses a brand new, high quality, encapsulated and wired visible (red) He-Ne Laser Head. The head is easy to handle and use. It has a very tight beam (0.95mR), making it intense at good distances, and more suitable for most applications. Head dimensions: 37mm diameter by 260mm long. Supplied with our newest 12V "Universal Laser Inverter" kit which powers all He-Ne tubes. This inverter comes with a totally prewound transformer, instructions, and even some plastic casing. Very easy to construct, and very efficient. The Special July - Sept. Price 77 An incredible: $175. 00 for the pair!! 2mW PHILIPS LASER HEAD WITH MAINS POWER SUPPLY (Kit No. LK13) Alternatively you can purchase the same 2mW Laser Head with a very small professional (Illustrated) 240V power supply, that even has a TTL interlock: needs 35V approx. 3mA, across two isolated terminals (Opto isolator built in the supply), to switch the laser ON. Nor, mally you would pay over $250 for the ·• supply alone, but during July August the price for the head and the 240V · · supply is an unbelievable: 00 $210. for the pair!! (Kit No. LK14) We also have a limited number of some larger 24 mW "Mellas Griot" laser heads with a similar deal (dimensions: 45mm diameter by 275 mm long .) LK16 - 2-4mW Melles Head with universal 12V kit supply : $225.00 LK17 - 2-4m W Melles head with mains supply: $260 .00 LASERS are not for kids: DANGER OATLEY ELECTRONICS PO BOX 89, OATLEY, NSW2223 Telephone: (02) 579 4985 Fax No: (02) 570 7910 Certified p&p: $5 in Aust. NZ (Alrmail):$10 Melbourne DistributorElectronics World (03) 723 3860 or (03) 723 3094 ]ULY1991 5 Installing multiple TV outlets, Pt.2 In Pt.1, we looked at the problem of antenna selection & briefly considered masthead amplifiers. This month, we show how the antenna signals are distributed to the various outlets. By JIM LAWLER When planning a master antenna TV (MATV) or community antenna TV (CATV) system, the one overriding consideration is to keep the signals at or above 60dBµ everywhere on the network. It is generally accepted that a TV set needs 60dBµ of signal to give a good picture. Some modern sets need less, but 60dBµ is a good basic figure to start with. If this can be achieved, then every set connected to the system will be able td deliver a good picture, just as if it was connected to its own private antenna. First , however, it is neces- sary to get a good signal from the antenna as detailed in Pt.1. Signal losses They say that electricity authorities are the biggest users of electrical power, due to the 1 2R losses in transmission lines. The same goes for TV signals in coaxial cable. Losses can be as high as 20dBµ per 100 metres and a big installation can involve several hundred metres of coax. When the signal level falls to 40dBµ, the picture will be almost lost in snow and there's likely to be no colour at all. Yet this is just the effect that would !---- : ,: _ : : : :.. :¥r::::--. -:»· ;;..i.u. The Hills Unilink Series of distribution amplifiers is available in several different models for operation on various TV bands. The gain is typically around 37dB and multi-band models have individual attenuators· with a range of 20dB to help balance the output signals. 6 SILICON CHIP be seen if an antenna delivered an average signal into one end of a 100metre cable, with the set connected to the other end. This problem can be solved in one of two ways: (1) either a much larger, higher gain antenna could be used; or (2) a distribution amplifier could be fitted between the antenna and the cable. Either way, the signal would have to be "launched" into the cable at not less than 80dBµ. If there is a second set connected to the cable, at the antenna end, then it could be overloaded by this 80dBµ signal. To ovucome this problem, it can be connected via a device that will shed 20dB~t of unwanted signal strength. Likewise, the signal fed to a set located near the centre of the cable would have to be reduced by lOdBµ to maintain a balance with the others on the line. Couplers The devices that couple the TV sets to the main cable and do the work of balancing the signal levels go by many different names. They can be called couplers, directional couplers, drop taps, tee junc. tions, tee-offs or tap-offs. I prefer the term "coupler", although the names all mean the same thing and the devices all do the same job. Another point that has to be considered is that of mutual interference between sets connected to the cable. This is less of a probleri1 with modern sets but still needs to be considered. The interference is caused by radiation from the local oscillators in the sets. When this oscillator is running at a frequency that falls within the video passband of another channel, any set tuned to the other channel will suffer picture degradation unless steps are taken to isolate the offending set. This is done by using directional couplers ~ TEE Hills also manufactures a range of high output distribution amplifiers with gains ranging from around 20db to 40dB. Most models cover the VHF bands from 40250MHz but wideband units are also available to cover the UHF bands as well. to connect each set to the line. Directional coup lers reduce local oscillator interference by doubling the impedance offered to the offending signal s as compared to th e desired off air signals. In some situations, very low value coupl ers (around 8clBµ) cause problems because they provid e insufficient isolat ion between sets. That said, any well-designed TV set should have very low radiation, so 8dBµ couplers usuall y work quite effectively. This then is the art of designing MATV and CATV systems. Th e signa l must be tailored so that no set receives too much or too little. And it must be done in a way that does not introduce ghosts, nois e or other unwanted products. Down to work Before a design can be implemented, two things must be known: (1) the signal strength at the antenna site; and (2) the length of the cable to the most distant set on the system. The only sure way of measuring signal strength is with a signal strength meter. Failing that, you can select an antenna to give a "ball park" figure, as detailed in last month's article. The distance to the furthest set can be measured directly or gleaned from the building plans. We also know that we will be using directional couplers of appropriate ratings and that we are not going to let any output go below 60dBµ. ~ TEE TEE Tee-units are used extensively in TV distribution systems to provide balanced signals to the network. They are available in 1-way, 2-way & 3-way types and several models are available within each type to give different Tee losses. The through-loss is typically 0.5-1.SdBµ. At this point, it wou ld be advisable to divide the proposed system in to a series of cable runs. It is desirable that eac:h run should be approximately the same length or should have about the same number of outlets. If this can be achieved, the design work is mad e much eas ier since the -figures derived for one leg will also apply to all the others. For example, in a multi-stor ey building you might have (n) id enti ca l runs where (n) equals the number of floors. Alternative ly, a small mot8I might have two wings of 12 units. plus an administration block with lounges, a large dini ng room, office. lobby and managerial quarters, again totall ing 10 or 12 outlets. But whatever the situation, the design breaks clown to grouping the out lets together into runs having the same number of sets and about the same length of cab le. You then start at the most distant outlet and work bac:k towards the antenna, adding the ex pected losses along the way. The most distant set will be connected to the line by way of a 12clB terminated coupler. The terminating resistor is vital on this coupler, to absorb the last trace of signal and prevent it being reflected back along the line. These reflections give rise to line ghosts and standing waves that can create havoc in this kind of system. A common result of standing waves is the cance llation of the colour signal. Reception can be in perfect black ancl white without a trac e of colour. The 12dBµ coup ler is about the lowest valu e normall y used but I have got by with 8dBµ units in areas where there is little chance of mutual interference because of the local channe l spacings. Let's stick with the usual values. We need 60dBµ of signal at the last set and will loose 12dBµ in th e cou pler. This nrnans that the signal into the coupler must bn at 72dBµ. Cable losses It is usual to measure the cab le run to the next outlet and calculate the loss in that length of cable . However, this is often only 0.25dBµ or 0.5dBµ and the calculations can get rather messy with all these tiny values being added in as you go. That may be the right way to do the job but it's far eas ier to calcu late an overall loss for the full length of cabl e, and acid this in as a lump sum at th e end. This method is not quite as accurate a calculating losses in incli vidual cable lengths. but is quite satisfactory in practice. So, we hav e reached the second coupler on the way back to the antenna. However, thn act of cutting the cable and inserting a coupler w ill introduce a loss into the system. In a well -d esigned coupler this loss will be quite small, although it does vary with the isolation value and the frequency at which it is being used. ]ULY 1991 7 ➔- 20dB I NURSE'S LOUNGE KITCHEN CHAPEL DINING ROOM ➔ RESIDENT'S LOUNGE 2-WAY SPLITTER 30dB --<) TV OUTLETS 4- AY SPLITTER I ~ ➔ ➔ I ~ I D SPLITTER [> AMPLIFIER ◊ OROPTAPS ADMINISTRATION BLOCK HOSPITAL AND RESIDENTIAL WEST WING This diagram shows the basic layout of a distribution system that was installed in a retirement home by the author over two years ago. In the installation, the antenna delivers about 65dBµ to an amplifier which raises the level to about 95dBµ. The 4-way splitter causes a loss of about 7dBµ in each leg and the Tee units (or droptaps) are then selected to give about 60dBµ of signal at each outlet. For instance, in the Hills Industries range of "Tee Units", insertion losses range from 0.2dBµ for a single coupler at VHF up to 4.8dBµ for a 4-way coupler at UHF. The exact values can be determined from the manufacturer's data sheet and should be used in any calculation. If the figures are not available, then a reasonable average value would be 0.8dBµ and 1.5dBµ for single and double couplers respectively. Insertion losses There are likely to be an appreciable number of these couplers along the cable, so the insertion losses must be added to the calculations. Again, I prefer to add these losses as a lump sum at the end of the design. At the second coupler, the signal in the main trunk will be a little bit above the 72dBµ seen at the last one. So another 12dBµ unit will suffice. But as we get closer to the antenna, the signal in the cab le rises steadily so 16, 20, 26 and even 32dBµ couplers will be needed to keep the level 8 SILICON CHIP to the TV sets at about 60dBµ. Let's calculate some figures for the north wing of a hypothetical motel in a reasonable signal area. The wing has 20 units, each three metres wide. They are numbered from "1" at the antenna end to "20" at the bush end of the verandah. This means that the cable run will be about 60 metres and so the cable loss will be 12-15dBµ overall, depending on cable quality. Let's settle for 15dBµ to allow for any miscalculations. This loss will not be added in just yet but its effect needs to be considered when calculating other values in the system. Depending on the layout of the units, it may be necessary to use 20 single couplers. However, if the units are mirror images of each other, then twin couplers might be more convenient. Note, however, that multiple units have a higher insertion loss so there is no advantage other than physical convenience. So, unit 20 will be fed with a single 12dBµ terminated coupler and the sig- nal into it will be 72dBµ. In this motel we can use twi1rcouplers, so units 16/17 and 18/19 are each fed through 12dBµ twin couplers. At units 12/13 and 14/15, we are getti ng toward the centre of the system and the signal level in the cable will be 4-5dBµ higher. This means that the coup lers feeding those rooms will need to be 16dBµ devices. Similarly, for units even closer to the antenna, 20, 26 and 32dBµ couplers will have to be used. So what will the signa l at 1111it 1 be? The insertion losses are 9 x 1.5dBµ for the double couplers plus 2 x 0.5dBµ for the single couplers. This gives a total insertion loss of about 14dBµ to which we must add the cab le loss of 15dBµ. If the level in the ceiling over unit 20 is 72dBµ, this means that the signal launched into the cable must be at 101dBµ (ie, 72 + 15 + 14dBµ). At this point I would check the coup ler selection for units 1 to 10. Unit 1 will have 101dBµ in its ceiling, so a 32dBµ coupler will leave 69dBµ for the TV. That's a little bit high but not so high as to be unmanageable. Unit 10 will see half the cable loss and half the insertion los ses, so it will have about 86dBµ overhead. A 20dBµ coupler will work well here and still leave 66dBµ for the TV. The same applies to the units on either side of number 10. If this motel has a second similar wing of units, they can use the same set of calculations. The two wings are connected together via a 2-way splitter which has a 3dBµ loss, so we are looking at an input to the splitter of 104dBµ. Boosting the signal Now that we know the required input to the system, we are in a position to consider the signal from the antenna. Let's assume that the selected antenna provides 68dBµ of clean signal and that it looks perfect on our test set. But 68dBµ is a long way short of the 104dBµ required for the head end of our system. In fact, we are looking for no less than 36dBµ of amplification. If you are of a mathematical bent, you will realise that this figure is very close to the total of the losses we expected to find in the system. This is not surprising really, since the aim is to supply every TV on the SERVICE IS... THE DIFFERENCE 101 Enhanced Keyboard r286-12 MHz Motherboard~ This Month only $299.00 {'urchase in July and receive 1Mb of RAM FREE_. Was $199.99 Now only $89.00 MOTHERBOARDS 8088 12Mhz 8088 12Mhz 640K installed 8088 12Mhz 1Mb installed 8088 31 Mhz 8088 31 Mhz 640K installed 8088 31 Mhz 1Mb installed 80286 12Mhz 80386 25Mhz Cache 80386 33Mhz Cache 80486 25Mhz Cache SUPER SPECIAL 8028616Mhz NEAT WAS NOW $ 129.00 $ 250.00 $ 300.00 $ 225.00 $ 335.00 $ 385.00 $ 350.00 $1995.00 $2495.00 $ 109.00 $ 199.00 $ 235.00 $ 189.00 $ 279.00 $ 319.00 $ 299.00 $1495.00 $1795.00 $4395.00 ASK FOR A r CLOCK CARD INCLUDING SOFTWARE "" COPY OF OUR Youwilloftenseethesecardsadvertisedelsewhereforaround$50.00. 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TAKE A LOOK AT THIS: e e e e 286-16MHz Landmark speed 20MHz 1 Mb of RAM 1.2 Mb Floppy disk drive • 42 Mb Hard disk drive • 16 bit 256K VGA graphics card • 14" Super VGA monitor • Serial & parallel ports .• Desk top case • 200 watt Power supply ONLY $1750.00 12MonthsWarranty 31MHzMOTHERBOARD SLOT EXTENSION KIT - Compatible with PC/XT/AT slots - Includes one extender card plus flat cable extension for four extended slots on one external module. - Excellent for test and repair of PC add-on cards. - The onboard power supply connector allows usage of external power sources for add-on cards on the extension module. The power fuses on the must be removed in this case to disconnect the +SV / +12V power supplies from the PC. - All pin-signal assignment of PC-bus are clearly marked on slot No 4 for easy testing/monitoring. 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I IIDI PRICES CURRENT FOR MONTH OF PUBLICATION OR WHILE STOCKS LAST SERVICE IS THE DIFFERENCE e SERVICE IS THE DIFFERENCE e SERVICE IS THE DIFFERENCE e SERVICE IS THE DIFFERENCE system with a signal that has the same strength as that direct from the antenna. Last month, I mentioned masthead amplifiers and said that they are "designed to amplify very small signals". But when we talk about distribution amplifiers, we are talking about a different animal altogether. In fact , an MHA is rather like a preamplifier in a hifi outfit while the distribution amplifier is more like the power amp lifier that drives the speakers. There's no way that a preamplifior can drive the speakers directly and, similarly, an MHA does not have enough "grunt" to feed more than one or two TV sets. A simple distribution amplifier will have two or three stages of wideband gain, with the final stage consisting of an RF power transistor. This output transistor wi ll dissipate 10-15 watts, so it's usuall y mounted on a substantial heatsink. In addition, the ampli fier must be well ventilated. More elaborate amplifiers will have the same three gain stages, but will also include filters to shape the bandpass or to eliminate unwanted frequency bands. Thon there are quite sophisticated amp lifi ers which process the three TV bands separately. The signals are passed first through a preamplifier, then through three bandpass filters to separate th e signals into two VHF bands and one UHF band. These are passed through separate variable gain amplifiers, before being recombined at the input to the final° amplifier. This kind of processing allows the signal response over the entire TV band to be adjusted to accommodate a wide range of signal levels. An even greater degree of sophistication can be achieved with "single channel" amplifiers. These are particularly useful in areas where both strong and weak channels occur in the same band. For example, a local channel 9 signal could overpower a distant channel 6 signal if any sort of wideband amplifier were used. But by using a channel 6 amplifier and leaving channel 9 to its own devices, the two could easily be accommodated on the one system. It 's also possible to purchase equipment that will convert one channel into another. This is particularly useful in areas where adjacent channel interference is common . It 's also useful when upgrading an existing installation which uses 300-ohm ribbon cable or old coax. Rather than rewire the entire premises for UHF signals, a downconverter can convert the high frequencies to channels in the VHF band which can then be distributed by the old cable. Problem sites One difficult job I came across was a motel of peculiar design, where the administration block was built in the centre between two long residential wings. The problem arose because the antenna could only be mounted at the remote end of one wing. If I had tried to launch the signal at a level high enough to reach the end of the far wing , I'd have completely swamped the sets in the units closest to the antenna. In the event, I had to use two separate amplifiers , one near the antenna as in the example above, and the second in place of the termi- Adjacent channel filters can be used if an adjacent unwanted channel interferes with a wanted channel. If both channels are wanted, it may be necessary to use a frequency converter to convert one channel to an alternative band. 10 SILICON CHIP 'The ML-20 Minilink is a wideband distribution amplifier for private homes or other small installations. It covers the frequency range from 45860MHz and features an in-built 2way splitter. The gain is 20dB up to band 4 & 16dB for band 5. nated coup ler at unit 20. The second amplifier lifted the 72dBµ of signal back to 100dBµ, before it had a chance to get down into noise. The administration block and the second wing of units were handled in the same way as the first, with a terminated coupler as the last component in the chain. In really large distribution systems, the signals are carried from a CBntral point to local distribution points on high-grade coaxial cables, often boosted by low-noise amplifiers. In some systems, the traditional coax cables are now being replaced by fibre optic links. The subscriber cables then radiate . out from the local distribution point, rather like the rays of a star, and are tapped to provide the signal that enters the home. Nevertheless, cabling a smal I motfll or a large city is different only in scale. Both systems demand clean signals of adequate level and this can only be delivered by careful design and careful installation, using quality cables, amplifiers and other hardware. Good luck with your particular installation! SC T'S SIMPLE RITHMETI ~ .> AT COMPATIBLE '286 MOTHERBOARD 20MHz NEAT AT MOTHERBOARD • • • • • • • • NEAT chip set allows total user control over system hardware • Memory expandable to 8Mb • Hardware/software selectable 8/10120MHz operation • Five 16-bit and three 8-bit expansion slots • Software selectable memory interleaving, wait states, and hard drive specs. • Socket for 80287 co-processor cat X-1003 Expandable to 1Mb or 4Mb (using 1Mb DRAMs) Keyboard/hardware selectable 8112MHz operation Six 16-bit and two 8-bit expansion slots Zero wait states with 80ns RAM Socket for 80287 co-processor 13.7 performance on Norton S. I. standard AMI Bios ROMs included LIMITED STOCKS Cat X-1002 •i ' • • I • HARD/ FLOPPY DISK CONTROLLER • • • • MFM disk controller for your AT compatible Requires one 16-bit expansion slot Includes cables to suit 1 hard drive & 2 floppies Compatible with 360k, 720k, 1.2Mb, 1.44Mb drive formats Cat X-2030 t~·l -~-; ~ ~ MINI XT MOTHERBOARD Super small and with outstanding performance! Ideal for anyone building a system from scratch ... or getting a deceased XT system on the road again. Constructed using multi-layer PC board and quality workmanship throughout. 8 expansion slots and up to 8.9MHz clock speed. Comes socketed for 640K RAM & fits any standard IBM compatible XT. Cat X-1001 8MB MEMORY BOARD This 8Mb IBM compatible memory board grows with your needs. Start out with just 2Mb, then expand it in lots of 2Mb up to its full 8Mb capacity. It uses standard 1Mb RAM chips and can be configured as expanded or extended ~ memory. EMS version 4.0 drivers • • come with the board along with user selectable 1/0 ports for page selection. Ok RAM supplied Cat X-1020 SERIAL/ PARALLEL GAME CARD A combined 1/0 card complete with one RS-232C serial port (second port optional), a parallel printer port & a joystick port as well! Serial ports are selectable from Com1 to Com4 & interrupt requests are selectable on all ports. Fits IBM compatibles & can be installed in just a few minutes. Cat X-2012 MAJOR DICK SMITH ELECTRONICS AUTHORISED STOCKISTS: NSW: ARMIDALE: New England Electronics 711655 BALLINA: Ballina Electronics 867022 BEGA: OZTECH Electronics 923933 BOWRAL: F.R.H. Electrical 611000 BROKEN HILL: Hobbies & Electronics 884098 COOTAMUNDRA: Cootamundra Music & Lite 422561 COFFS HARBOUR: Coffs Harbour Electronics 525684 OENILIOUIN: Deni Electronics 813672 OUBBO: Chris's Hi Fi 828711 FORSTER: Forster Village Electronics 545006 GLEN INNES: John Sommerlad Electronics 323661 GRAFTON : Repairs & Spares 421911 GRI FFI TH: Miatronics 624534 INVERELL: lnverell Electronics 221821 KEMPSEY : P&L Leonard 631134 LEETON: Leeton Audiotronic 532800 LIGHTNING RIDGE: Cycle & Sound 290579 LITHGOW: Douroy Photographies 513173 LISMORE: Decro Electronic Services 2141 37 MOREE: Moree El ectronics 522091 MUDGEE: Headware 723895 NARRABRI : Namoi Computer Service 923274 NELSON BAY : Nel son Bay Elect & Hobbies 813685 NOWRA: Nowra Electronics 21 0722 PARKES: Strad Music Ctr 623366 PORT MACQUARIE: Hastings Com puter Service 834574 RICHMOND: Silicon Crafts 784101 TAREE: Brads Electronics 526603 WAGGA WAGGA: Phillips Electronics 216558 WELLINGTON: Wellington Service 452325 WINOOR: Silicon Crafts n6722 VASS: W.rmington Electrical 26111 6 YOUNG: K~th Donges Electronics 821279 VIC: BAIRNSOALE: LH & LM Crawford 525677 COLAC: Colac Electronics 312847 MILDURA: Pullman Auto Pro 232882 SHEPPARTON: Andrew Guyatt Electronics 219497 SWAN HILL: Nyah District TV Service 329303 TRARALGON: Traralgon Electronics 741699 WARRAGUL Roylaine 234255 WARRNAMBOOL: Koroit St El ec Services 6274 17 OLD: AYR· Delta Electrix 831566 BUNOABERG: Bob Elkin Electronics 521785 CALOUNDRA: Electro-mart 918533 DYSART: 1 1 ~1~1loW:tHM·K~~1.zt:~~t~i4~~ ~a:~~r"i 1~i~~n~6;i~~p~f1~: 1 ~~~ON~ii/r~1f~1~~ t~i~sWm~~~Mr~~~B~~ • ~ ~~~~c;:i~ ~~~~~tio~i~r'2~:6ll~~~t1~c~L~ii a;i~~ TV & Comp World 822788 WHYALLA: Eyre Electronics 454764 WA: ALBANY: Micro Electronics 412077 BUNBURY: Micro Electronics 216222 GERALOTON: Batavia Lighting & Electrical 211278 KALGOORLIE: Today's Electronics 215212 KARRATHA: Daves Oscitronic 854iD6 MANORAH: Micro Ele<;tronics 5812206 PORT HEOLANO: Ivan Tomek the Elect J32531 ~~~~~1~~%1 :~i~rt: A must when installing expansion cards or changing memory chips. Stray static charges can destroy chips in an instant. The Anti-static wrist strap has adjustable fastening, a coiled ground lead, & a high value series resistor for added safetv. Cat X-2042 ~Xm'. Not all products may be available at all stores. We suggest you phone to ch eck availability. l\eN POCKET '9f•J =t-3 DUAL 'Pockef Sized Digital Multimeter Combined Analog/Digital Multimeter There are compact meters.... and then there's our new truly pocket sized multimeter (it's about the size of a small calculator). It features auto ranging, data hold, diode test and continuity as well as all the usual DMM features. Cat 0-1575 • 3200 Count • Bargraph • Overload protection • DCV: 300mV, 3, 30, 300, 450V • ACV: 3,30, 300,450V • Resistance: 300, 3K, 30K, · 300K, 3M, 30Mohm If you've ever wished for an accurate digital meter with the readability of an analog meter then here is the solution - a digital multimeter combined with a full sized analog meter! • DCV 200mV, 2V, 20V, 200V, 1000V • ACV(rms) 200mV, 2V, 20V, 200V, 750V . • AC(rms) & DC current 20uA, 200uA, 2mA, 20mA, 200mA, 2A, 1OA • Resistance 200, 2k, 20k, 200k, 2M, 20M ohms • dB -45dB to +50dB (4 ranges) • Audible continuity • Diode check Cat Q-1700 5 With ·true HMS! 199 COMPUTER ~t~=~r PENCIL With BuiH-in Logic Tsster! Probe}pe !iM~~~diest own! It features data hold, fixed and auto ranging, diode test, audible continuity check plus a full 3½ digit LCD display. Ideal for work on circuit boards! • DCV: 200mV, 2, 20, 200, 500V • ACV: 2, 20, 200, 500V • AC/DC Current: 200mA • Resistance: 200, 2K, 20K, 200K, 2M. 20M ohms • Auto Polarity indication • ~~ftQ~1a;~ pouch . s5995 !!~~Mllt!J ?!., .• ~j(ij; PHONES SECURITY AUDIO COMPUTERS Digital Multimeter with RS-232 Interface A high quality performance multimeter that can find and hold minimum and maximum readings as well as measure relative offsets and handle currents up to a huge 20A (AC/DC). What's more, you can locate intermittent faults by monitoring and storing the output of your meter on computer. The meter has a 20 segment bar graph and comes with an RS-232 cable and computer program disk. • DCV: 200mV, 2V, 20, 200, 1000 • ACV: 200mV, 2V, 20, 200, 750 • Current AC/DC: 2mA, 200, 20A • Resistance: 200ohm, 2Kohm, 20, 200, 2Mohm, 20 • Capacitance: 2000pF, 200nF, 20uF • Frequency counter: 20kHz, 200 • Diode and Continuity check • Transi~or, Frequency & Logic Cat0-1570 $215 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. 0/Nite Courier Available. 24 HOUR DESPATCH OF ALL ORDERS NSW • Albury 21 8399 • Bankstown Square 707 4888 • Blacktown 671 n22 • Brookvale 905 0441 • Bondi 3871444 • Campbelltown 27 2199 • Chatswood Chase4111955 • Chullora 642 8922 • Gore Hill 439 5311 • Gosford 25 0235 • Hornsby 477 6633 • Hurstville 580 8622 • Kotara 56 2092 • Liverpool 6009888 • Maitland 33 7866 • Miranda 525 2722 • Newcastle 611896 • North Ryde 878 3855 • Parramatta 689 2188 • Penrith 32 3400 • Railway Square 211 3n7 • Syc;!ney City 267 9111 • Tamworth 66 1711 • Wollongong 28 3800 ACT • Belconnen (06) 253 1785 • Fyshwick 80 4944 VIC • Ballarat 31 5433 • Bendigo 43 0388 • Box Hill 890 0699 • Coburg 383 4455 • Dandenong 794 93n • East Brighton 592 2366 • Essendon 379 7444 • Footscray 689 2055 • Frankston 783 9144 • Geelong 232 711 • Melbourne City 399 Elizabeth St 326 6088 and 246 Bourke St 639 0396 • Richmond 428 1614 • Ringwood 879 5338 • Springvale 547 0522 QLD • Brisbane City 229 93n •Buranda 391 6233 • Cairns 311 515 • Chermside 359 6255 • Redbank 288 5599 • Rockhampton 27 9644 • Southport 32 9033 • Toowoomba 38 4300 • Townsville 72 5722 • Underwood 341 0844 • SA • Adelaide City 223 4122 • Beverley 347 1900 • Elizab~th 255 6099 • Enfield 260 6088 • St. Marys 277 89n WA• Cannington 451 8666 • Fremantle 335 9733 • Perth City 481 3261 • Midland 250 1460 • North bridge 328 6944 TAS • Hobart 31 0800 NT • Stuart Park 81 1977 B1152/TI Unlike most simple battery chargers, this clever 6/12 volt SLA (sealed lead acid) battery charger continuously monitors the battery voltage, and then automatically adjusts the charge rate to suit. Apart from having four LED indicators and five switchable charge rates, our charger maintains the battery at a constant float voltage once it has been fully recharged. This means it can remain connected to the battery indefinitely and still keep it in peak condition! Short form kit with all components, hardware & front panel label. This switch mode power supply can really "';,i,, ootoot Imm 0 to 100 volts DC! Ideal for TV servicing. dei;,e, fue goods wifu Cat K-3220 Do you have two-way light switches in your home and would like them replaced with touch dimmers? We have just the thing! This extension touch plate is connected in parallel to the K-3001 main unit. Now you can switch your lights on and off or dim them from two locations. Cat K-3002 f=Jftl -, i July '89 =.!iJJJ FLEXITIMER QQQ~ S219 rzlQ LIC.J 12/24V LIGHT CHASER We call this little gadget the 'Flexitimer' because it uses just a handful of components to accurately time intervals from just a few seconds to a whole day! It's relay can switch a number of different output devices and the circuit can be easily modified or incorporated into a much larger project. This is a short form kit with circuit board and components only. This simple circuit can produce some pretty impressive effects! It has four separate channels which can each power 36 watts of light bulbs ie : 12 x 3W. A single rotary control allows you to vary the flash rate from about a ¼ second up to 2 seconds. This is a full form kit containing all components, hardware & case plus LEDs for testing the channel outputs. Cat K-3163 Ma rch '91 Mains -:- _Kits marked with this symbol involve mains power wiring. Take extreme care when working with this equipment. Degree Of Simplicity $30 TOUCH LAMP EXTENSION This unit can turn your light on and off or dim them just by touching the decorative plate. The unit is suitable for dimming incandescent lamps rated from 25 watts up to 300 watts total. ""' ~, g '!1; , ~ cat K-3001 ~!Jj;/ ...,, June '89 cat K-3595 / • Current output is 1.7A <at> 0-87V and 1A <at> 100V • Voltage is variable from 0-100V 'll-:JJ.!Jii#,~ • LED indicator for ripple exceeding 'ff.!fJ'Jj 5mV p-p March '90 • Short-circuit protected • Pre-punched & screened front panel Case H-2812 & • This kit is supplied compleie transformer M-2000 Cat K-3465 SAVE not included HURRY... LIMITED STOCK! TOUCH LAMP DIMMER <at> ~ Q QQ QQQ Simple Intermediate Detailed ~ :JJ-51:=J.!).;.~ ~~L!J. April '91 Q 52995 VINTAGE RADIO By JOHN HILL Some simple repair techniques Every now and then I devote my vintage radio column to a getting out of trouble theme. This usually covers various repair techniques that have helped me overcome some of the many problems encountered while restoring old radio components to working order. Several months ago, I described the restoration of a 1932 model Howard, a 4-valve console radio with turned legs. In this particular story, mention was made of repairs to the dial drum, the tuning capacitor and the speaker transformer, but few details were given as to what these repairs actually involved. This month's column will give those details. The dial drum was the most troublesome of the three repairs, simply because it is an old diecasting. Modern diecastings are of good quality and give little or no trouble , but the diecastings of 50 years ago are another matter. Unfortunately, a considerable number of old dial components were diecast and can present the vintage radio restorer with many a headache. Most early diecastings were made of zinc and when first manufactured they were perfectly OK. However, due to impurities in the zinc, the metal was not stable and over long periods of time it became distorted and very crystalline in its grain structure. This ageing effect resulted in extreme brittleness. The weak nature of the Howard's diecast dial drum became apparent when it was gripped lightly in a lathe chuck - it simply fell to pieces as one of the accompanying photographs clearly shows. The centre piece had already been broken and the lathe effort succeeded in reducing the drum to five individual bits. This problem could have been solved by giving the shattered remains to my brother Alan (who is much cleverer than I). If necessary, he can cast a new aluminium dial drum for me using the reconstructed original as a pattern. However, getting someone else to fix things is cheating a bit so I decided to do what other collectors would be forced to do; to repair the part by gluing it back together again. If the repair fails at some time in the future, then brother Al may have a job to do after all. The glue operation worked 0ut reasonably well and the dial drum is now in one piece again and fully operational. Araldite® was used as an adhesive although Superglue® may have been stronger. The problem when using Superglue® is that it does not allow sufficient time to accurately position the bits before it sets. Vintage radio restorers should take heed of the problems one can encounter when working with old diecastings. Simply dropping a diecast component on the floor could shatter it into a dozen or so pieces. The nickname "muck-metal" is most appropriate for old diecastings. Tuning capacitor This dial drum became a problem when it broke into several pieces after being lightly clamped in a lathe. The unit was subsequently repaired by gluing the pieces together using Araldite®. 14 SILICON CHIP The tuning capacitor on the Howard is a simple single section type, typical of regenerative detector receivers of This dismantled tuning capacitor is from my 4-valve Howard receiver. Tuning capacitors are much easier to clean & repair if they are first removed from the chassis and dismantled. that era. It is of plain bearing construction and, like most old tuning capacitors, was in need of attention in the bearing department. Not only was the front bearing quite loose but the unit was also in need of a thorough clean-up. There is only one way to successfully service a component such as a tuning capacitor and that is on the workbench. Trying to repair one while it is still attached to the chassis can be rather awkward. It was therefore removed for servicing. Dismantling the tuning capacitor was easy. Two screws held the moveable plates to the control shaft, while another two screws secured the main bearing to the front endplate. The rear bearing consists of a 60° tapered setscrew (with a lock nut) which bears in a centre hole at the rear of the control shaft. Front bearing As can be seen in one of the accompanying photographs, the front bearing is split and the excess clearance is taken up simply by squeezing the sides of the bearing together with a pair of The completed dial drum, after it was glued back together again. Note the steel plate that's used to reinforce the centre section. If further problems are encountered, a new dial drum will be cast using aluminium. pliers. Such a bearing should be adjusted so that it is a light drag fit on the shaft. Because the tuning plates were not centrally spaced, the front bearing was packed with a thin cardboard gasket. This made up for the discrepancy caused by wear in the thrust bearing. The thrust bearing takes the pressure that is exerted by the adjustable setscrew at the back of the tuner. Once again, only gentle pressure should be brought to bear on the thrust bearing and the rear setscrew was adjusted accordingly when the unit was assembled. The moveable plates of the tuning capacitor are earthed through the front bearing, the thrust bearing and the rear setscrew. Therefore, these bearing surfaces need to be clean and under tension in order to give a reliable noise-free earth connection. The combined bearing pressures resulted in a noticeable resistance when the control shaft was turned. However, when the dial drum was fitted , the extra leverage of the large diameter drum reduced the resistance to a seemingly negligible amount and the dial cord drives the unit without slipping. Similar repairs may also be required in more elaborate receivers, such as TRFs with multiple gang tuning capacitors , particularly if the capacitor is of the plain bearing type. Once again , the job is made easier if the capacitor is removed from the chassis. The Howard's tuning capacitor uses a split front main bearing. This is adjusted by squeezing the sides inwards using a pair of pliers. The bearing was also packed with a cardboard spacer to compensate for wear. JULY 1991 15 The moveable plates are secured to the control shaft by two grub screws and are earthed via the front and rear bearings. These bearings should be clean and under tension to ensure a reliable connection. With multi-gang capacitors, it is also advisable to check the capacitance of each gang. This can be done using a digital multimeter which has a capacitance range. If necessary, minor capacitance adjustments can be made by bending the outside moveable plates. Loudspeaker transformer The final repair to the old Howard involved replacement of the output or loudspeaker transformer. This problem took a while to locate at the time because the speaker was working prior to removing it from the cabinet. For reasons unknown, the speaker then stopped working and, looking back, it was probably the cleaning brush and a blast of compressed air that did the dirty deed. A defective speaker transformer is a very common fault in vintage radios. In days long gone, speaker transformer failure was so common that special winding replacements were made for the job. Instead of replacing Just like new - the Howard's tuning capacitor after cleaning, painting and re-assembly. The old plain bearing tuning capacitor is serviceable once again & was subsequently refitted to the Howard receiver. the whole transformer, the transformer laminations were split and the defective windings removed and replaced with new windings (see photo). The problem is, such spares are no longer available and, if trouble is encountered, replacement of the defective unit is the only real alternative. A secondhand unit is not always the answer, however. The replacement may last for years or it could pack it in the next day. One never knows! Obviously, a new transformer is the better approach but such devices are now difficult to obtain. There is, however, another alternative. Most present-day electronics dealers stock audio line transformer as standard items. These transformers have tapped primary and secondary windings, are rated at four watts and cost about $7.00. According to the Dick Smith Electronics catalog, their audio line transformer (Cat. M-1100) has both 2.5kQ and 5kQ primary taps; 2, 4, 8, and 16Q secondary taps; and is rated at * * * For all your: Electronic Components Tools & test equipment Kits Security Remote Control and Computer accessories. You can also get us to design and service your equipment. * * 'e " i:'i !,.;:_:_.:~_-::_-:::,;;-,::-.:.:' _ Call NEWTRONICS 131 Pacific Hwy Charlestown, NSW, 2290 16 SILICON CHIP Mail order from your phone Tel: (049) 439 600 or by Fax: (049) 439 809 4W. It is intended for use with PA systems on 70V or 100V lines. On the basis of the above specifications , these transformers would seem to be well suited to the task. The 5kQ primary is close to the 7kQ impedance specified for most pentode output valves, while the secondary taps would accommodate any likely loudspeaker voice coil. While these transformers are not valve output transformers in the true sense of the term, they do the job very well. I have used dozens of them as speaker transformers in a wide variety of applications and they have all worked quite OK. They are a convenient over-the-counter substitute and if anyone is having a supply problem in this regard, then at least give them a try. The main limitation of these transformers is that, being designed for line work, they don't have an air gap. This is normally provided in a transformer designed to carry direct (plate) current, as well as audio. The practical result would be reduced inductance and some loss of bass response. Many early speaker transformers had a small tagstrip attached to them. This tagstrip terminated the transformer leads and the leads from the radio and to voice coil. A modern line transformer will not only lack this tagstrip but will also be too small to fir the original mounting holes. This makes installation quite difficult. This problem can be ove rcome by simply installing the new transformer in the old mounting cover. The excess space can be taken up by inserting wooden wedges down the sides to 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. Old speaker transformers were made to be serviced and new windings could be installed with little effort. Unfortunately, the windings are no longer available as spare parts. 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 The book of facts! FERROMAGNETIC CORES Modern audio line transformers such as the Altronics 1105 (left) and the M-1100 from Dick Smith Electronics (centre) make useful replacements for defective speaker transformers. The unit at right is an 1105 that's been transplanted into an old transformer mounting cover. hold things in place. If the wedges are installed with a liberal application of "Silastic", the new transformer will be held quite securely in place. One favourable aspect of using the old transformer mounting cover is that it makes the replacement transformer a good deal less noticeable than if it were mounted by itself. What's more, because the old transformer cover usually has the tag strip riveted to it, the original wiring arrangements can be maintained. Maintaining appearances The originality aspect of a vintage radio restoration is usually quite im- portant. If a receiver still looks original after it has been restored, it not only gives the restorer a great deal of satisfaction but the set also retains its value. On the other hand, if the set obviously looks as though it has been modified with inappropriate replacements, then the illusion of a desirable old original fades a little. Restoring original parts to working order and disguising modern components to look like old are just some of the problems the vintage radio repairer has to come to terms with. How well these repairs are done is up to the skill and determination of individual restorers. SC • Materials • Design • Applications :., illA.midmt Complete data on over 500 types of Iron Powder and Ferrite cores and assemblies, all available in Australia!$'/:! post paid from: 5•n U. U STEWART ELECTRONIC COMPONENTS Pty. Ltd. ACN004 518898 P 0. Box 281 Hunt1ngdale 3166 PH (03)543-3733 FAX (03)543-7238 JULY 1991 17 Tuning in to satellite T\T, Pt.2 This month, we take a look at the satellites that are visible from Australia and discuss the hardware requirements for C an'd Ku-band reception. We also include a few tips on aiming the dish. By GARRY CRATT The most popular C-band satellite amongst satellite TV enthusiasts is Intelsat 5, located at 180E 0 • This satellite, or "bird" as they are often called, carries links from the USA for several commercial television networks in Australia, as well as one transponder for the US Armed Forces Radio and TV Service, Cable Network News (CNN), and some French programming for the Polynesian islands. These transmissions are not made to any published schedule, although most are at regular times. They are not intended for reception by commercial organisations other than the transponder lessee. The material transmitted is also copyright. However, the amateur satellite enthusiast will find the reception of these programs most interesting, both from a technical point of view and from a contents point of view. No licence is required to receive this information, provided the material is not used for commercial purposes and the copyright is preserved. Table 1 shows the C and Ku-band satellites visible from Australia. To receive Intelsat and the other Cband satellites, the minimum dish size required to produce acceptable results is 3.5 metres. With a dish this size plus a good LNB having a noise temperature of less than 50°K, and by using "threshold extension" techniques such as narrow IF filters, it is possible to produce entertainment quality pictures and sound. However, there is no performance margin when using such a (relatively) small dish, and so signals are likely to deteriorate as the satellite ages or during periods of heavy rain. A larger dish will provide more gain and give some performance margin above threshold, thus allowing some headroom. As transponders are leased to customers, performance and programming can change dramatically from year to year. For example, transponders using a hemispherical beam can be switched to a lower intensity global beam, thus resulting in a weaker signal. In addition, satellites can be moved or even replaced in time, so any deci 0 sion to establish a satellite TV system must be based on the knowledge that reception cannot be guaranteed long term. However, experience has indicated that the use of satellites as a delivery method for TV programming is becoming more popular as time goes by, so reception from at least one satellite should always be possible. Signal coding There is also a growing trend for transponder lessees to use some method of encryption to scramble satellite signals, in order to protect sensitive material from interception. On the Intelsat satellites visible from Australia, several commercial TV net- Basic Scheme For An Aussat Ground Station MONITOR LNB RECEIVER 00 O Cl 18 SILICON CHIP D Fig.I: to set up a ~round station, you need a dish, a low-noise block (which is mounted on the dish), a receiver & a TV monitor. The LNB provides frequency conversion to the first IF (1450-950MHz) & these signals are then converted by the receiver to a second IF at 70MHz. works use a system called "vidiplexing". This system is not really encryption in the true sense of the word. It allows more efficient use of a transponder (or half transponder) by mixing two video frames together, each from a different source. Separating the two video signals is quite a simple matter and is easily done by using a video monitor which has been turned on its side, so that the two frames can be displayed vertically. This also involves rotating the yoke 90°. Fig.2 shows this technique. An inexpensive b&w set or computer monitor can be used for this purpose .. However, in spite of the growing trend to scramble transponders, there is still plenty of satellite activity which uses no encryption at all and is unlikely to ever do so. The Aussat system For the reception of Ku-band satellite signals in Australia, Aussat is really the only signal source available. There are three Aussat satellites in orbit at present, providing an interesting mix of program material. To establish a Ku-band system, capable of good results, the minimum dish size is considered to be 1.5 metres. This allows the reception of usable pictures from the low power (12 watt) transponders. The Aussat satellite system comprises three satellites: Aussat 1 at 160°, Aussat 2 at 156°, and Aussat 3 at 164°. The services carried on these satellites are listed in Table 2. Aussat carries three systems for delivering television. The first is a DBS (Direct Broadcast Service) which utilises B-MAC as the transmission mode. This system is based on propdetary technology, devised by Scientific Atlanta in the USA and licensed to Plessey Australia, which produces B-MAC receivers locally. B-MAC signals are supposed to provide superior video and audio reception, compared to the standard PAL system. These signals can only be received by authorised B-MAC receivers. The transponders used for this service are high power (30 watt) and good results can be achieved using a 1.0 or 1.2-metre dish. Unfortunately, the cost of a B-MAC receiver (which will also receive PAL signals) is quite high, at around $2000, and without one, no intelligible pictures or sound can be received. It is Table 1: Satellites In ITU Region 3 Satellite Country Location Band Statsionar 13 USSR 80° East C-Band DFH2-A1* China 87.5° East C-Band Statsionar 6 USSR 90° East C-Band lnsat 1C India 94.5° East C/S or C/Ka Band DFH2-A3* China 98° East C-Band Statsionar-T USSR 99° East UHF Asiasat* China 105.5° East C-Band Palapa B1 Indonesia 108° East C-Band BS-2B* Japan 110° East C-Band DFH2-A2* China 110.5° East C-Band Palapa B2P Indonesia 113° East C-Band Palapa B3 Indonesia 118° East C-Band Superbird A* Japan 128° East Ku/Ka Band CS-3A* Japan 132° East C/S or C/Ka Band CS-3B* Japan 136° East C/S or C/Ka Band Statsionar 7 USSR 140° East Ku/Ka Band JCSat 1* Japan 150° East Ku-Band JCSat 2* Japan 154° East Ku-Band Aussat A2 Australia 156° East Ku-Band Aussat A1 Australia 160° East Ku-Band Aussat A3 Australia 164° East Ku-Band Intelsat V F3 174° East C/Ku-Band Intelsat V F1 177° East C/Ku-Band Intelsat V F8 180° East C/Ku-Band *N ot visible from Australia unlikely that the B-MAC encryption system will ever be broken by software hackers and there is little reason for anyone to attempt to do so. This DBS system was designed for installation as a consumer product in rural areas and operates a regular published program service. High quality audio (stereo) programs are also carried. The RCTS service The second system carried by Aussat is a regional distribution service for TV stations around Australia. This systems is known as RCTS, or the Remote Commercial Television Service. Some commercial networks use the RCTS system to transfer program material interstate to their own studios. These links are generally scrambled, using a system called E-PAL. In this scrambling technique, the video signal is inverted, the sync removed, and the audio signal is inserted into the vertical blanking area. Considerable circuitry is required to unscramble E-PAL and, because all program material is subject to copyright, there is little point in expending any effort to decode these signals. There is, however, another service carried on Aussat which is unscrambled and of significant interest. This JULY 1991 19 is the "news interchange" service , and is designed to allow regional Earth stations to recover news items for inclusion in local news programs. Much of this information is broadcast in the form of pre-edited news items, ready for video editing. However, there are also many hours of direct un-edited programming re-broadcast (after standards conversion) by Aussat Master Control from the Intelsat 4GHz service, from which the programming originated. Typically, services such as CNN, Skynet, BBC World News and many others can be received in the course of any 24-hour period. Of course, this programming is often interrupted by local news event coverage, transmission of promotional material, and test patterns. In fact, there is sufficient unencoded program material broadcast to justify the establishment of a ground station, the cost of which can be kept to less than $1000, as we shall see. You can now afford a satellite TV system For many years you have probably looked at satellite TV systems and thought "one day". You can now purchase the following K band system for only $995. 00 This is about 1/3 the price of comparable 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. • One super low noise LNB (low noise block converter) l.4dB or better. • One KU band feedhorn and all the mounting hardware as well as a magnetic signal polariser. Radio programming • 30 metres oflow loss coaxial cable with a single pair control line. In addition to TV services, Aussat also carries radio programming from Radio Australia, the ABC and one commercial network. The Department of Aviation also uses the satellite system for air to ground communications, particularly in remote areas. All these services use SCPC as the transmission mode. So when all three satellites are considered, there are many • A 99 channel infrared control satellite receiver with adj ustable 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. services of potential interest to enthusiasts. Selecting the hardware Having decided to procure an Earth station, it is important to select the correct hardware. Whether the decision is made to build a C-band Earth station or a Ku-band station, the receiver that is used is common to both systems. Basically, the receiver converts a block of frequencies from 9501450MHz to "baseband" signals, comprising video and audio. This process is common to both C and Ku systems. Apart from the cable that feeds the receiver from the LNB, this is where the hardware similarity ends. For starters, the C and Ku bands use LNBs with vastly different frequency characteristics. Also, due to the frequencies used, the size of a suitable dish is much larger for C-bahd than Ku. Note that in all instances , a larger diameter dish will provide better results, as will an LNB having a lower noise temperature. Aiming the dish Assuming that the correct combination of hardware has been selected, the next step is to determine where to locate and point the dish. Because the locations of both the satellite and the proposed Earth station are known, a mathematical calculation can be made to determine the necessary dish elevation and azimuth. Fig.3 shows a CALL, FAX or WRITE to AV-COMM PTY LTD. PO BOX 386, NORTHBRIDGE NSW 2063 PHONE (02) 949 7417 FAX (02) 949 7095 All items are available seperately. Ask about our low noise 'C' band LNB, and other interesting products. All systems are provided with dish pointing details. ----------- 1 Yes Garry, Please send me more information I on your K band satellite systems. I Name ........ ....... ... ........ ........ ... .. I I Address .............. .... ... ..... .. .. .. ... I ................................................... I ........................... P/Code ........ . . I I Telephone .. . . . . . . . . .. .. .. . . . . . . . . .. . . . . . Ii, ~N= ~ !:. - 20 - - - - SILICON CHIP -0= I I I I I I I I I .I Fig.2: vidiplexed signals can be separated by using a video monitor which has been turned on its side & its yoke rotated by 90°, so that the two frames can be displayed vertically. A b&w monitor is best used for this purpose. A typical satellite receiver is shown next to the monitor. · Table 2: Aussat Services Transponder Polarity Satellite (Aussat 1,2,3) Programming Coding 1 V 1 Network 9 EPAL 9 H 1 Network 9 PAL 2 V For lease 10 H DOA, Aussat Data 3 V 11 H 4 V 1 Network 10 PAL 12 H 1 ABC PAL 5 V 1 SBS BMAC 13 H 3 1 2UW/Macquarie SCPC 1 Network 7 EPAL Q Net ABC Radio 6 V 1 Network 10 EPAL 14 H 1 2 ABC HACBSS Skychannel BMAC BMAC 7 V 1 ABC HACBSS BMAC 15 H 3 Network 9 PAL 8 V 2 ABC HACBSS BMAC BASIC computer program that can be used to calculate these parameters. Alternatively, most satellite hardware suppliers will provide the "pointing" information on request. Only two tools are necessary to enable you to accurately point the dish: a magnetic compass and a protractor. A compass is necessary to find the direction that corresponds to the correct azimuth. Note, however, that there are "lines of magnetic variation" crossing the Earth's surface, and these variations must be taken into account . when using the "heading" that has been mathematically calculated. For example, the magnetic variation for Sydney is -11 °. This means that 11 ° must be subtracted from the calculated azimuth heading. The easiest way to set up a dish is to set the ele·v ation first. This can be done by using a protractor, a length of cotton and a weight to measure the angle of elevation (this can be done from the back of the dish). Once the elevation has.been set, the dish can be manually turned (ie, the azimuth adjusted) until a signal is received. Obviously, this alignment procedure will be much easier if all receiving equipment, including the video monitor (or TV set), is temporarily . located next to the dish. Another method of alignment is to use a receiver that has been pre-tuned to the correct satellite channels, or to use a receiver fitted with a "scan" facility. By connecting a digital voltmeter across the receiver signal strength meter, the slight increases in signal strength which occur as the dish is moved closer to optimum alignment can be used as a pointing aid. This technique can also be used to align the feedhorn and to optimise the LNB probe rotation, prior to fitting any polarising device. Motorised drive If reception from more than one satellite is required, a motorised drive system can be employed. In this instance, a mechanical adjustment for the angle of declination must be built into the dish mount, to compensate for the location of the Earth station. In greater detail, all satellites pur- sue a circular orbit but this orbit is with reference to the equator. As the Earth station location gets further from the equator, the satellites appear to be in an elliptical orbit and so cannot be tracked by simply rotating the dish. This problem can be corrected by building a mechanical compensation into the dish mount. A far simpler system, considering the relatively small number of satellites viewable from Australia, is to mark both elevation and azimuth on the dish mount and mounting pole with an indelible marker for each satellite. The dish can then be manually adjusted whenever a different satellite is required. Once the dish is mounted, the LNB can be affixed to the feedhorn and polarotor if used. In the case oflntelsat reception, the feed can be configured to LHCP (left hand circular polarisation), or to RHCP in the case of the Russian Gorizont satellites. If building a Ku-band Earth station to view Aussat, a feedhorn capable of selecting either polarity (vertical or horizontal) will be necessary. Note that mechanical polarity changers have significant losses (as SATELLITE ENTIIUSIASTS! • • 1.5M Dishes complete $445 High performance Ku Band Hemt LNC's 2 yrs warranty.. $370 • Complete B-Mac Systems .. $2895.00 • Complete C Band Systems • Dishes Small through to Large • Pal Receivers ... $595.00 • Complete range of cables, connectors and accessories Call now for FREE Catalog, Information Bulletin and SPECIALS .. (02) 489 5474 Videosat Pty. Ltd. 83 Alexandria Pde. Wahroonga ' NSW 2076 [ ~VIDEOS~Ilj Fax (02) 489 3557 Mr/Mrs/Ms ...................................... . Address ......... ................................... . Telephone ....................................SCj ul91 * For all your Satellite Needs - Nationwide * JULY1991 21 will be the case if any object is placed in the feedhorn). Electronic polarity changers using the Faraday effect technique have far less losses and hence offer considerable advantages over their mechanical counterparts. The cable used to connect the LNB to the receiver should be a low-loss 75-ohm type. RG-59 or, better still, RG-6 or RG-11 is preferred, although air-dielectric copper and aluminium wrap braided UHF TV coaxial cable can be used in some cases . However, cheap cables with solid dielectric and single copper braid will not work at all over significant distances. Type "F" connectors are universally used to terminate the cables. In addition, steps should be taken to weatherproof the LNB cable connection. This can be done by using a rubber spark plug cover, as commonly supplied by auto accessory shops. These rubber boots form a snug fit over the cable and connector on the LNB. A non-acid based silicone sealant (neutral cure, as sold for metal roofing) should be used around the seal between the cable and the boot. Because a polarity changer is necessary for a fully equipped Ku-band system, special coaxial cable which contains two separate conductors (one to feed the control voltage) should be used. Typically, these special cables are available in lengths of 30 and 50 metres. This dual function cable will greatly simplify the installation of a Ku-band system. Australian suppliers of satellite equipment cater mainly for commercial Ku-band installations or remote area C-band systems. They can be found in the Telecom Yellow Pages in most capital cities. Most are able to supply and install equipment almost immediately. Next month, we will take a look at a complete ground station that you can purchase for less than $1000. It comes complete with a 1.8-metre dish antenna and is ideal for tuning into the Aussat satellites. Fig.3: Antenna Pointing Program 10 CLS:PRINT 'GEOSTATIONARY SATELLITE BEARINGS FOR SOUTHERN HEMISPHERE" 20 PRINT" - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -": PRINT 30 INPUT "ENTER YOUR LATITUDE IN DEGREES AND DECIMAL DEGREES (E.G. 30.855)";A 40 INPUT "ENTER YOUR LONGITUDE IN DEGREES AND DECIMAL DEGREES (E.G. 152.922)";0 50 INPUT'ENTER THE SATELLITE LONGITUDE IN DEGREES EAST ";Y 60 INPUT "MAGNETIC DEVIATION FOR DISH LOCATION (0 IF NOT KNOWN) "; MD 70 IF Y>O THEN GOTO 110 80 IF Y<O THEN GOTO 90 90 B=O-Y 100 GOTO 120 110B=Y-Q 120 C=A • .017 4533 130 D=B *.0174533 140 E=SIN(C) 150 F=TAN(D) 160 H=3.1416+ATN((F/E)) 170 AZ=H*180/3.1416-180 180 IF Y>O THEN GOTO 220 190 IF Y<O THEN GOTO 200 200 AS=360-AZ 210 GOTO 230 220 AS=AZ 230 J=(COS(C) *COS(D)) 240 CA=·ATN(J/SQR(-J* J+ 1))+ 1.5708 250 CB=CA*180/3.1416 260 R=3957 270 K=22245 280 RA=SOR((R*R)+(R+K) * (R+K)-2* R*(R+K) *COS(CA)) 290 T=((RA *RA+(R*R)-((R+K)* (R+K)))/(2*RA *R)) 300 TL=-ATN(T/SQR(-T*T+1))+ 1.5708 310 EL=(TL*180/3.1416)-90 320 RB=RA *1.609344 330 PRINT:PRINT "- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -" 340 IF EL<=5 THEN GOTO 440 350 PRINT 'AZIMUTH = ";AS;" DEGREES FROM TRUE NORTH " 360 IF MD=O THEN GOTO 380 370 PRINT 'AZIMUTH = "; (AS+(MD));" DEGREES FROM MAGNETIC NORTH" 380 PRINT "ELEVATION = ";EL;" DEGREES" 390 PRINT "RANGE = "; RB;" KILOMETRES" 400 PRINT:PRINT:PRINT "PRESS ANY KEY TO CONTINUE OR E TO END" 410 A$="" 420 A$=INKEY$ IF A$='"' THEN GOTO 420 430 IF (A$="E") OR (A$="e") THEN GOTO 460 ELSE GOTO 10 440 PRINT "SATELLITE TOO LOW .... ELEVATION IS ";EL;" DEGREES" 450 GOTO 400 460 END Example Run of Program ENTER YOUR LATITUDE IN DEGREES AND DECIMAL DEGREES (E.G. 30.855) 30.855 ENTER YOUR LONGITUDE IN DEGREES AND DECIMAL DEGREES (E.G. 152.922) 152.922 ENTER THE SATELLITE LONGITUDE IN DEGREES EAST 160 MAGNETIC DEVIATION FOR DISH LOCATION (0 IF NOT KNOWN) 0 AZIMUTH ELEVATION RANGE = 13.60957 DEGREES FROM TRUE NORTH = 53.23546 DEGREES = 36893.85 KILOMETRES Further reading (1). "Aussat Network Designers Guide" - Aussat. (2). "The Complete Guide To Satellite TV" - Tab Books. (3). "Build a Personal Earth Station for Worldwide Satellite TV Reception" - Tab Books. (4). "1991 World Satellite Alma22 SILICON CHIP nac", by Mark Long (available from Opac Pty Ltd, 99 Boundary Rd , Peakhurst. Phone 02 584 1233). (5). "Satellite & Cable TV Scrambling and Descrambling", by Brent Gale & Frank Baylin. (6). "Troubleshooting & Repairing Satellite TV Systems " - Tab Books. (7). "The Hidden Signals on Satellite TV" , by Thomas P. Harrington & Bob Cooper Jnr. - Howard Sams Books. (8). "Ku Band Satellite TV Theory, Installation and Repair" , by Frank Baylin & Brent Gale. SC Monitor Madness !! 14" Super VGA Colour Monitor (1024x768) 14" TTL Mono Monitors Green, Amber or Paper white plus 16 bit 256k VGA Card .28mm Dot Pitch Normally $249 Normally $874 This Month ONLY $199 YOU Save $50 This Month ONLY $649 Mono Card to suit above YOU Save $225 Normally $99 This Month $69 Save $30 Full 12 months warranty applies. r-------~~----------------------------, . ffiGH QUALITY, ELECTRONIC 1 ~o~~~~~~~~~~ I I -~if~~:~:~~~"' 0 CC:J i;,-◊ ~'\: •;~i~~~ SOLUTIONS SYSTEMS ~ (Other Systems available - Please Call) 386-33MHz 64KCache 286-12MHz 386SX-16MHz Includes: Includes: lMbRAM 1.2Mb Floppy 42Mb Hard Drive 16 Bit 256K VGA card Enhanced 101 keyboard Serial, Parallel and Games port Hinged Baby AT desktop case and 200WPSU 14 in o~()(}Monitor 1Mb Ram on board 1.2Mb Floppy drive 42Mb Hard Drive 2 Serial, 1 Parallel port 16 Bit 256K VGA card Enhanced 101 keyboard Desktop or mini tower case and 200W PSU 1Mb RAM on board 1.2Mb Floppy Drive 42Mb Hard Disk 2 Serial, 1 Parallel Ports 16 Bit 256K VGA card Enhanced 101 keyboard Desktop or Midi Tower case with LED display and 200W power supply 14 in 14 in s$1795 '------------- s$2395~00onitor Includes: s$3395~00onitor ------------ ___________ J GOVERNMENT & WHOLESALE ENQUIRIES WELCOME ( except software and hard disks). YOUR GUARANTEE OF SATISFACTION: * All products carry a 14 day money back guarantee * All prices include sales tax. * All motherboards carry a fu 1112 month warranty. * All cards come with full documentation * All other products carry a full 3 month warranty. a.~m-111111 Ir Due to Technical advances, products we supply may in some cases vary from those pictured. In all cases the products supplied are guaranteed to perform to an equal or higher standard than those pictured : -[Z] ~ei991Su":~::~er~~~;;~al---co'o~; :o'w~~1~i;, ;ndu7 ~~ I I this coupon to receive your FREE copy: I Mr/Mrs/Ms: _ _ _ _ _ _ _ _ _ _ _ _ __ Electroni~ Solutions Sales P/L 1 Address: _ _ _ _ _ _ _ _ _ _ _ _ _ __ 5 Waltham St. Artarmon 2064 PO Box 426 Gladesville 2111 1 I Suburb: _ _ _ _ _ _ _ _ State: _ _ _ _ Postcode:_ _ I Note: Please do not send back this coupon if you purchased from us in 1990 or returned the 1ieIep h one: (02) 906 6666 I previously issued card to be included on the mailing list, you will receive the catalogue Fax: (02) 906 5222 automatically. 07/91 Battery discharge pacer for electric vehicles I Based on a handful of low-cost ICs, this project can indicate the percentage amperehour capacity used or remaining in a rechargeable battery. Alternatively, it can be used as a "fuel" pacer to obtain maximum performance from an electric racing car. By DIETER KUENNE A common problem with rechargeable batteries is determining how much of their charge capacity has been used. This project is designed to give you that sort of information and can be wired to give readings in one of three modes. Of course, it does require careful calibration to match the battery being used but we'll give you 24 SILICON CHIP all those details later. The circuit to be described is similar to one installed in a battery-powered racing car called the "Rocket", developed by Ian Sims of Ferntree Gully, Victoria. A flat battery is a common problem with electric racing cars, due to over-zealous use of the "throttle". However, with the Battery Dis- charge Pacer on board, the state of charge can be monitored to obtain the best performance while conserving battery charge in order to finish the race. In fact, the first time that the Pacer was used in the "Rocket", it won the race. As used in the "Rocket", the unit operates in "Pacer" mode. 1!1 this mode, the unit integrates the current drawn from the battery and compares this value with the integral of the energy (average discharge current) that should have been used to that time. The difference between these two values is shown on the IPeter, which is set to give a centre-zero reading. If the resultant is zero, then you will get the maximum performance from your available energy source. A deflection to the right indicates surplus energy, while a deflection to the left indicates that the discharge is faster than the desired rate. Thus, depending on how the unit is calibrated, the "Pacer" mode can be used to optimise vehicle range or to Although shown here with a small sealed lead acid battery, the Discharge Pacer can be used to monitor virtually any rechargeable battery. The unit can be wired to show percentage charge used or charge remaining, or it can be used as a "fuel" pacer for an electric car. Power for the unit is supplied from the battery being monitored. obtain maximum speed over a given distance. The other two operational modes are similar to each other and indicate the degree of battery discharge. You can wire the unit to show either the percentage ampere-hour capacity used or the percentage ampere-hour capacity remaining (ie, the unit operates just like a fuel gauge). As well as monitoring conventional 12V car batteries , you can also use the unit to monitor nicad battery packs. In fact, you can calibrate the unit to monitor virtually any rechargeable battery. Note that the unit always assumes that you are starting off with a fullycharged battery. Note also that the unit cannot be used in reverse; ie, it cannot be used as a charging indicator. Presentation The circuitry for the Battery Discharge Pacer is housed in a small plastic instrument case. In addition to the meter, there are just two switches on the front panel. One switch powers up the device, while the second resets the reading to zero. In use, the unit can be powered from the battery being monitored. Because it draws only 11.SmA, it will have negligible effect on the ampere hour capacity of a car battery and only a small effect on a large nicad battery pack. Block diagram Fig. 1 shows the block diagram of the Battery Discharge Pacer circuit and shows how it is connected to a load consisting of a motor and its associated controller. However, you can use the circuit to monitor a battery driving virtually any kind of load; the principle is exactly the same. As can be seen from Fig.1 , the battery supplies power to both the motor via its controller and to the circuit via S1. The power supply circuit regulates the battery supply to +5V and also generates a -5V rail for the circuit. If the battery voltage is above 30V, the input for the circuit power supply must be derived from a battery tapping lower than 30V. In most cases , this simply involves tapping into a nominal 12V or 24V point above the ground reference. As shown on Fig.1, a shunt resistor is added in series with the motor (or load). At switch on, current flows through the motor and also through the shunt resistor which produces a voltage proportional to that current. This voltage is then amplified and filtered to prevent noise upsetting the circuit. The following stage consists of VCO1 which is a voltage controlled oscillator. Its output frequency (F1) is determined by the voltage applied to it by the amplifier/filter stage. The output from the VCO is then applied either to the count-up input or countdown input of an UP/DOWN counter via an input selector. The counter outputs are in turn applied to an 8-bit digital-to-analog converter (DAC) which produces a voltage that 's proportional to the digital count applied to it. This analog voltage is then amplified and used to drive the meter which has its negative terminal connected to VREFZ. This voltage reference allows the meter to deflect fully left for a count of hex 00, fully right for a count of FF and to mid-scale for a count of 80. Initially, at power up, the counter is preset to either hexadecimal 00 for the "Charge Used" mode, FF for the "Charge Remaining" mode or 80 for the "Pacer" mode. In addition, VCO1 's output is connected to the UP input of ]ULY1991 25 AD- MOTOR AMPLIFIER MOTOR CONTROLLER VC01 SHUNT UP/DOWN INPUT SELECTOR VREF1 +1.2V + BATTERY VC02 UP/DOWN COUNTER F2 OV AMPLIF_IER '!' I I S1 OAC ..L. i CIRCUIT POWER SUPPLY -sv VAEF2 .,. .,. Fig.I: the block diagram of the Battery Discharge Pacer. In operation, the circuit monitors the voltage developed across a shunt resistor in series with the load & uses this voltage to control the frequency ofVCOI. This VCO then drives a counter, the output of which is fed to a digital-to-analog converter (DAC) to derive a voltage that's proportional to the digital count. The DAC then drives a meter movement to show either the charge remaining or the charge used. In the "Pacer" mode, VCOI drives the DOWN input of the counter, while VC02 (which operates at a fixed frequency) drives the UP input. the counter for the "Charge Used" mode and to the DOWN input for the "Ch arge Remaining" and "Pacer" modes. It is now simply a matter of counting the pulses from VCOl to obtain either the "Charge Used" or "Charge Remaining''. Pacer mode For the Pacer mode, it is necessary to subtract the A.h (ampere-hour) value that should have been used up to a certain point from the value actually used. This is achieved by using a second voltage controlled oscillator, VCOZ, to drive the UP/DOWN counter. Its output frequency is set to a fixed value by the voltage app lied to it from VREFl. In operation, VCOl drives the DOWN input of the counter while VCOZ drives the UP input. The frequency of VCOl is then adjusted so that Fl equals F2 at the discharge rate required to just flatten the battery at the desired time. This is indicated by a zero reading on the centre-zero reading meter. However, if the discharge rate is greater than the required rate, Fl will be greater than FZ and so the counter will count down and the meter will deflect to the left. Conversely, if the discharge rate is too low, the counter 26 SILICON CHIP will count up and the meter will deflect to the right. Circuit details Refer now to Fig. 2 which shows the circuit details. Before getting down to the nitty-gritty, let's quickly relate the various sections to the block diagram. The two VCO circuits are easy to spot and cons ist of op amps IC2d & IC2c (VCOl) and IC2a & IC2b (VCOZ) . Of the remaining sections, IClc is the amplifier/filter section; ICs 5-7 the UP/DOWN counter; IC8 the DAC; D5 & D6, VREFl; and ICla, VREF2. As already mentioned, power is derived from the battery being monitored and this is applied to the circuit via a lOQ resistor and 30V zener diode (ZDl). ZDl is there to clip voltage transients or noise spikes (eg, from the motor) to prevent damage to the following circuitry. The supply rail is then fed via Sl to REGl which is an LP2950CZ-5 3-terminal regulator. This particular regulator was chosen for a number ofreasons but mainly for its low quiescent current. Typically, it can supply lOOmA while drawing a quiescent current of just 75µA . The output is also very accurate at 5V ±50mV and it can remain in regulation with an input voltage that's only 138mV greater .than the output voltage. In addition , the temp erature coefficient of the output voltage is just 15Dppm/°C, which m eans that the regulator can be used as a voltage reference. A standard 3-terminal regulator (such as the 7805) should not be substituted for REGl. Its output is nowhere near as accurate and it would introduce an extra l0mA of current drain . The negative supply rail for the circuit is obtained using an LMC7660 Switched Capacitor Voltage Converter (IC9). Fig.3 shows the internal workings of the LMC7660. It contains four CMOS switches which are shown here as Sl, SZ, S3 and S4. Sl and S3 operate together, while SZ and S4 operate together. When Sl and S3 are closed, SZ and S4 are open and when Sl and S3 are open, SZ and S4 are closed. Now lets see how it works. When Sl and S3 are closed, Cl charges to the V + supply vo ltage which in our case is +5V. Sl and S3 are then opened and SZ and S4 are closed. The positive side of Cl is now connected to ground and the opposite Fig.2 (right): the main circuit contains all the elements shown in the block diagram (Fig.I). The two VCO circuits are easy to spot and consist of op amps IC2d & IC2c (VCOI) and IC2a & IC2b (VC02). Of the remaining sections, ICic is the amplifier/filter section; ICs 5-7 the UP/DOWN counter; IC8 the DAC; D5 & D6, VREFI; and ICia, VREF2. N '-I -< ..... (Cl co ..... C: ---... 1 ~-' +5V A e VREF1 0 LK3 , , LK6 11 01! 16 10 C jB 021 IC5 40193 ~ 131 CARRY 12' oowN eoRRO 15,A 4 s u~OAO LK2 LK1 -1 . 7 2x1N414~ ~ - 12 0.11 I 8 . . 00 7 OC 6 "~ QA UPi OOWN COUNTERS 910 1olc 11 IC6 40193 ) oowN eonnowl 13 16 I •5V - 5V 220k 220k ~ ·:-~ ·-- I~ I - 5V OlT ') 1 VC02 -i 12k I I - 5V 390k "Vf' J'~ I CARRYl12 15,A 4 I i 5 u~oAo J. ,5V 0.1 -II- !- VR1 ,h 330kl BATTERY DISCHARGE PACER 16VWI 1 1N~i4BJ; LKs ' ' LK4 RWTll B2ki 06 1N4 14B +5V 1 ~ BATTERY : T MOTOR +5V 01 !.!!. .,. A -2.lo 1QJC, 11.e ,sl 1 VC01 IC7 40193 .,. QC 6 QB 2 Q 3 :l ·,loow I IUP ·,1 LOA 1~ 03 1N4148 0.1 47k l 471 VR(Fl 100k 88 81 82 83 -5V 9 · 85 10 86 11 87 12 5 6 7 B 84 ~ 'fj v- ICB OACDBOO VLCl1 011 82k or .,. 10 16VW 10 35VWI ~ q 0.1 09 1N4148'f 08 1N4148 4.7k 4. 7k IC9 LMC7660 ,- 5V GNO REG 1 POWER LP2950CZ5 • ,u..---,0UT S1~ ~ , - - - - - - • 5V I N ~.OUT VIEWED FROM BELOW 5-30V(MAX) 1:0!? +5V---<I>------, I" • 2.2k 1mA ..W, 27k 100!1 _J. • 1 2V -5 V -• 5V PARTS LIST 1 PC board, code SC11108911, 123 x 135mm 1 front panel label, 140 x 55mm 1 meter scale label, 51 x 40mm 1 plastic instrument case, 154 x 65 x 158mm 1 MU45 1mA meter 1 SPDT toggle switch 1 push-on momentary switch 1 5mm ID grommet 1 300mm-length twin hookup wire 1 500mm-length 0.8mm tinned copper wire (for links) 10 PC stakes 4 self-tapping screws 1 100kQ miniature horizontal trimpot (VR1) 1 10kQ miniature horizontal trimpot (VR2) 1 1kQ trimpot (required for testing only) Semiconductors 2 LM324 quad op amps (IC1 ,IC2) 1 4066 quad CMOS analog switch (IC3) 1 4011 quad NANO gate (IC4) 3 40193 4-bit binary up/down counters (IC5,IC6,IC7) 1 DAC0800 digital to analog converter {IC8) 1 LMC7660 negative voltage generator (IC9) 1 LP2950CZ5.0V 5V regulator (REG1) 1 30V 1W zener diode (ZD1) 91N4148, 1N914 switching diodes (D1 -D9) Capacitors 1 10µF 35VW PC electrolytic 2 10µF 16VW PC electrolytic 2 1µF 16VW PC electrolytic 8 0.1 µF metallised polyester 3 .01 µF metallised polyester Resistors (0.25W, 1%) 1 390kQ 1 27kQ 1 330kQ 1 22kQ (for testing) 10 220kQ 1 12kQ 8 100kQ 5 4.7kQ 3 82kQ 1 2.2kQ 2 47kQ 1 100Q 1 36kQ 1 10Q side of Cl, which is now at V- or -5V, connected to CZ via S4. After a few cycles of this process, CZ charges to V- to provide the -5V rail. In practice, an internal oscillator which normally operates at about 10kHz provides a clock signal to drive Sl and S3. At the same time, an inverted version of this signal is used to drive SZ and S4 so that the two pairs of CMOS switches operate 180° out of phase. Shunt input When the motor is running (or power is applied to the load), the voltage developed across shunt resistor RSHUNT is proportional to the current. This voltage is fed to a low pass RC filter (100kQ and 0.lµF) and limited to ±600mVby clipping diodes Dl and DZ before being fed to pin 10 of op amp stage IClc. Normally, however, the voltage across the shunt is less than zoom V. VRl, its series 330kQ resistor and the lOOkQ input resistor form a voltage divider which allows adjustment of the voltage applied to pin 10 of IClc from the shunt resistor. IClc has a gain of about 34, while the 0. lµF capacitor across its feedback resistor rolls off the response above 4Hz. The amplified and filtered signal from IClc is now fed to voltage controlled oscillator VCO1 (ICZd, ICZc & IC3a). ICZd operates as an integrator by virtue of the 0.lµF capacitor connected between its output (pin 14) and the inverting input at pin 13 . When the output ofIClc goes positive with respect to ground, pin 13 ofICZd will be more positive than pin 12 due to the voltage divider (2 x ZZ0kQ) at the non-inverting input and so pin 14 of ICZd will swing towards -5V. The 0. lµF capacitor on pin 14 now charges towards the negative supply rail via the series ZZ0kQ resistors on v+ = 5V S2 8 I 3 .,. I c1 - I I I 28 SILICON CHIP S4 I 4 CLOCK SIGNAL I I I 531 Miscellaneous Hookup wire, resistor or enamelled copper wire for motor shunt (see text). pin 13 and the resulting signal fed to the inverting input (pin 9) of Schmitt trigger stage ICZc. When ICZd 's output voltage reaches the negative threshold of ICZc, pin 8 of ICZc switches high and closes CMOS switch IC3a. IC3a now connects a 220kQ resistor to ground and this in turn pulls the inverting input ofICZd below the noninverting input. As a result, ICZd's output now swings high and the 0. lµF capacitor charges towards the positive supply rail. When the output of ICZd reaches the positive threshold of Schmitt trigger ICZc, pin 8 of ICZc goes low again and IC3a opens . ICZd now begins charging the 0. lµF capacitor towards the negative supply rail and so the process is repeated indefinitely. Thus, we have an oscillator which increases in frequency as the control voltage at the output ofIClc increases. VCOZ operates in exactly the same manner as VCOl. It consists of ICZa, ICZb and CMOS analog switch IC3b. In this case, however, the control voltage is fixed at 1.2V (VREF1) by two forward biased diodes, D5 & D6. When link LK1 is in place, VCOZ is enabled and the circuit operates in "Pacer" mode. When LKZ is in position, VCOZ is disabled and the circuit op erates in "discharge" mode. Note that the outputs of Schmitt triggers ICZc and ICZb both swing between -5V and +5V. In each case, this is converted to a 0V to +5V swing by a voltage divider consisting of two l00kQ resistors connected in series to the +5V rail. The outputs of the voltage dividers in turn drive NAND gates IC4b and IC4c. These two NAND gates simply buffer and invert the Schmitt trigger outputs. Thus, when ICZc's output switches high , pin 4 of IC4b sw itches low and pin 3 of IC4a remains high. INVERTER c2 I: 5 o,-.....--ovour = -v+ = -5V Fig.3: how the LMC7660 negative voltage generator IC works. It use an internal oscillator to drive two pairs if switches 180° out of phase so that C2 charges to -5V. CHARGE USED MODE CHARGE REMAINING MODE Fig.4: before mounting the parts on the PC board, decide on the mode you wish to use & install thl),necessary solder brides on the copper side of the board as shown here. Make sure that you install the bridges exactly as shown & that you don't short out adjacent tracks. Once the bridgl)s are in place, you can attend to the linking options on the component side of the board (see text & Fig.5). Conversely, when IC2c's output goes low, pin 4 of IC4b switches high and pulls pin 2 of IC4a high. At the same time, pin 1 ofIC4a is pulled high via a .0lµF capacitor and so IC4a's output (pin 3) goes low. The .0lµF capacitor on pins 1 and 2 of IC4a now charges via its associated 82kQ resistor. When the voltage on pin 1 falls below the lower threshold of the NAND gate input, the output of IC4a goes high again. Diode D4 prevents a large negative voltage from appearing on pin 1 ofIC4a when IC4b's output subsequently switches low again. Thus, IC4a provides a brief (0.8ms) negative-going pulse each time pin 8 of IC2c goes low. Similarly, IC4d provides a brief negative-going pulse each time pin 7 of Schmitt trigger ICZb goes low. Counters NAND gates IC4a and IC4d drive the UP & DOWN clock inputs of binary counter IC5, either via links LK3 & LK4 or links LK5 & LK6. LK3 & LK4 are used for the "Pacer" and "Charge Remaining" modes, while LK5 & LK6 are used for "Charge Used" mode. IC5 is a presettable UP/DOWN binary counter. This means that it can initially be set to a particular count under the control of the load input at pin 11. The preload count inputs are at pins 15, 1, 10 & 9 (A, B, C & D) and these are linked either to +5V or ground to obtain the necessary preload count. IC6 and IC7 are also binary presettable UP/DOWN counters and are connected in cascaded mode to IC5. Note that the CARRY output of IC5 is connected to the UP input of IC6, and the CARRY output of IC6 is connected to the UP input of IC7. Similarly the BORROW outputs of IC5 and IC6 connect to the DOWN inputs of the following stages. This configuration allows the three counters to operate together as a 12bit UP/DOWN counter. However, only the most significant eight bits from the counter are connected to Digital to Analog Converter IC8 (ie, IC5 operates only as a divide-by-16 stage). The LOAD inputs of IC5, IC6 & IC7 are all tied together so that the counters are simultaneously preloaded with their required counts. Initially, when power is first applied, the LOAD inputs are all pulled low via the lµF capacitor across SZ, and the counts at the preload inputs are loaded into the counters. The 1µF capacitor then charges via an 82kQ resistor, at which point preloading ceases and the counters are ready to begin counting. Alternatively, RESET switch SZ can initiate preloading at any time (ie, reset the counters) by simply discharging the 1µF capacitor. Digital-to analog converter IC8 is an 8-bit digital-to-analog converter (DAC) which has differential current outputs (!OUT & !OUT-bar) at pins 2 & 4. It is a relatively easy DAC to connect up. The inputs are at PACER MODE B1-B8 (pins 5-12) and these control the output of the DAC. In addition, the DAC requires two current reference inputs, one at pin 14 (VREF+) and the other at pin 15 (VREF-). There are many ways to configure the reference inputs and this circuit uses a positive current reference derived via a 4. 7kQ resistor from VREF1 (1.2V), while the VREF- input is connected to ground via a second 4. 7kQ resistor. Diodes D8 and D9 at the VLC terminal (pin 1) set the IC for CMOS input levels (connecting this pin directly to ground sets the IC for TTL input levels). Compensation for the DAC is provided by the .0lµF capacitor from pin 16 to the -5V supply. The differential current outputs . from IC8 at pins 2 & 4 are converted to a voltage output using differential amplifier IClb. The output of this op amp varies from -1.ZV if all zeros (lows) are applied to the B1 -B8 inputs to+ 1.2V if all ones (highs) are applied to the B1 -B8 inputs. When the inputs are all zeros except for a one at the most significant input (Bl), IClb's output is at ground (0V). For example, let's say that we want the unit to operate in "Pacer" mode; ie, with the meter starting off at centre zero. In this case, we simply preload 0000 into counters IC5 & IC6 and 1000 into counter IC7. (ie, a count of 800 hex is loaded). Similarly, if we want the unit to operate in "Charge Used" mode, 0000 is loaded into all counters (ie, 000 hex) to get -1.ZV at the output ofIClb. Finally, for the "Charge Remaining" mode, a count of 1111 r'nust be preloaded into each counter (ie, FFF hex). IClb drives the positive terminal of ]ULY 1991 29 +5-30V GND VRSHUNT Fig.5: before mounting any of the parts, install the mode select links as described in the text, depending on which mode you wish to use. The remaining parts can then be installed but don't mount RSHUNT until after the calibration procedure. For low-current applications, RSHUNT can be a standard resistor while for heavy current applications, it should be made up from a length of tinned copper wire (see table) & mounted off the board adjacent to the load. the 1mA meter via series 100Q and 2.2kQ resistors. The negative terminal of the meter is held at -1.2V by VREF2 (IC1a) so that we get a centrezero reading when IC1b's output is at ov. IC1a is simply a buffer ampl,ifier which has an output equal to the voltage on its non-inverting input at pin 3. VR2 and the 36kQ and lO0kQ resistors set this voltage to -1 .2V, while the 27kQ resistor equalises the source resistance on the inverting input with that on the non-inverting input to minimise output voltage drift. Construction Most of the parts for the Battery Discharge Pacer are mounted on a PC board coded SCl 1108911 and measuring 123 x 135mm. Before starting construction, check your PC board carefully against the published pattern. It will be much easier to locate and repair any board defects at this stage. 30 SILICON CHIP At this stage, you also have to decide on the mode of operation you require; ie, "Charge Used", "Charge Remaining", or "Pacer". Each option requires different linking arrangements on the PC board, to connect the VCOs to counter IC5 and to set the preload values for the counters. Fig.4 shows the preload connections for each of the three options. They are implemented by installing solder bridges across the copper tracks in the positions indicated. Fig.5 shows the linking options for the VCOs. Here's what to do for each mode: Charge used mode: this mode uses only VCO1. Install solder bridges to preload 0000 into all counters as shown in Fig.4. Install link LK2 (to disable VCO2) and links LK5 & LK6, as shown in Fig.5. Charge remaining mode: similar to "charge used" mode. Install solder bridges to preload 1111 into all counters (Fig.4) and install links LK2, LK3 and LK4. Pacer mode: install solder bridges as shown on Fig.4, then install links LK1, LK3 & LK4 as shown on Fig.5. Once the programming links and preload bridges have been installed, the remaining parts can be mounted on the PC board. Do not place anything in the RSHUNT position at this stage, since this value must be calculated to suit your particular application. · The order of parts assembly on the PC board is unimportant but make sure that all polarised parts are correctly oriented. These parts include the ICs, the diodes and the electrolytic capacitors. Install PC stakes at all external wiring points. Final assembly The completed PC board assembly can now be installed inside the case, along _with the front panel switches and the meter. Begin by drilling the mounting holes for the two switches, then mark out the mounting holes for the meter using the drilling template supplied. Position the meter so that it's right in the centre of the panel. This done, drill numerous small holes around the inside circumference of the large meter clearance hole and knock out the centre piece. Clean up the hole with a file, then drill the four screw-mounting holes using the correct sized drill. The front panel label can now be stuck to the front panel and the holes cut out using a sharp utility knife and reamer. It's up to you as to whether or not you replace the meter scale with a new artwork. To remove the old scale, first unclip the plastic cover, then carefully undo the two meter scale screws. The new meter scale can then be installed and the cover clipped back into place. Note that the scale published here is suitable for both the "charge remaining" and "charge used" modes. For the "Pacer" mode, only a centrezero mark is required on the meter scale. The meter and the switches can now be installed on the front panel and the rear panel drilled to take a single rubber grommet. This done, secure the PC board to the integral standoffs using self-tapping screws and complete the wiring as shown in Fig.5 . Testing The first step in testing the unit is to apply power (6-30V DC) and check the voltages at the supply pins of the ICs. ICl and ICZ should have +5V on pin 4 and -5V on pin 11; IC3 should have +5V on pin 14 and -5V on pin 7; IC4 should have +5V on pin 14 and OV on pin 7; ICs 5, 6 and 7 should have +5V on pin 16 and OV on pin 8; ICB should have +5V on pin 13 and . ;- -- 7 ! - -- - - : " 7 ' ~ . µ , - - - - - - W ] - - - ,I; ur- _r , ,. < Take care with the ICs when you are installing them on the board since they don't all face in the same direction. In particular, note that ICl & IC2 face in the opposite direction to IC3 & IC4 (see Fig.5). The board is secured to integral standoffs on the bottom of the case using self-tapping screws. RESISTOR COLOUR CODES 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 No. Value 4-Band Code (5%) 5-Band Code (1 %) 1 1 10 8 3 2 390kQ 330kQ 220kQ 100kQ 82kQ 47kQ 36kQ 27kQ 22kQ 12kQ 4.?kQ 2.2kQ 100Q 10Q orange white yellow gold orange orange yellow gold red red yellow gold brown black yellow gold grey red orange gold yellow violet orange gold orange blue orange gold red violet orange gold red red orange gold brown red orange gold yellow violet red gold red red red gold brown black brown gold brown black black gold orange white black orange brown orange orange black orange brown red red black orange brown brown black black orange brown grey red black red brown yellow violet black red brown orange bll!e black red brown red violet black red brown red red black red brown brown red black red brown yellow violet black brown brown . red red black brown brown brown black black black brown brown black black gold brown 1 1 1 5 JULY 1991 31 Diameter (mm) 3.149 2.500 2.000 1.600 1.250 1.000 0.800 0.630 0.500 0.400 0.315 Current Rating (A) Resistance mQ/metre 15 7.5 4.5 2.9 2.3 1.5 1.1 0.7 0.3 0.2 0.1 2.212 3.512 5.488 8.575 14.05 21.95 34.30 55.31 87.81 137.2 221.2 -5V on pin 3; and IC9 should have +5V on pin 8, 0V on pin 3 and -5V on pin 5. If any of these voltages is incorrect, check the PC tracks for shorts or open circuits. If the -5V supply is not present, check the circuit around IC9. When power is first applied or when the Reset is pressed, counters IC5, 6 and 7 are preloaded as discussed previously. You can check this by measuring the voltage at pin 7 ofIClb. This voltage should be -1.ZV when the preload is 000 (charge used mode); 0V when the preload is 800 (pacer mode); and + 1.2V when the preload is FFF (charge remaining mode). Assuming everything checks out so far, the voltage on the meter negative terminal can be set to -1.ZV using VRZ. To do this, press the RESET switch and adjust VRZ so that the meter reads 0% when the preload is 000, 50% or mid-scale when the preload is 800 and 100% when the preload is FFF. creased and deflect to the right if the voltage is decreased. In the charge used mode, the meter should rise gradually when 52mV is applied to the VRSHUNT input, until eventually it reaches full scale on the meter and then falls to zero again. Similarly, in the "charge remaining" mode, the meter reading should gradually fall from full scale to zero reading and then jump to full scale again. Calibration The unit can now be checked for correct operation by applying a voltage of 52mV to the shunt input. This can easily be done using a 22kQ resistor and lkQ potentiometer. One end of the resistor is connected to the +5V supply and the other end to one side of the pot. The other side of the pot is connected to circuit ground, while the wiper is connected to the VRSHUNT input. It's now simply a matter of adjusting the trimpot to obtain 52mV at the shunt input (check this voltage with your multimeter). If you are set up in the "Pacer" mode, the meter should remain close to the centre reading but may have some drift to the left or right. Check that this reading can be reset with the RESET switch. Now check the effect on the meter when you increase or decrease the shunt voltage. It should gradually deflect to the left if the voltage is in- To calibrate the unit, set VRl to mid-scale, apply 52mV to the VRSHUNT input and observe the meter. Adjust this voltage until it takes exactly 1 hour for the meter to travel from 0 to 100% in the "charge used" mode or from 100% to 0% in the "charge remaining" mode. For the "Pacer" mode adjust the input voltage until the meter needle remains stationary. By the way, you don't have to spend an hour observing the meter before making each successive adjustment. For example, in the "Charge Used" or "Charge Remaining" modes, the meter needle should move by 20% over a 12-minute period. Use this shorter time interval for your initial adjustments, then use a longer interval to make sure that the shunt voltage is spot on. The shunt voltage should now be measured and recorded as the calibration voltage for your Battery Discharge Pacer. The shunt resistor The calibration voltage is now used to calculate the value of the shunt resistor (RSHUNT) required. For the "Charge Used" and "Charge Remaining" modes, RSHUNT is equal to the BATTERY:-, DISCHARGE PACER • • RESE~ 32 SILICON CHIP Fig.6: this full-size artwork can be used as a drilling template for the front panel. The meter is supplied with its own drilling template . 00 I I!.! ~ -0-0 ~ 0 Fig. 7: check your PC board against this full-size pattern & repair any defects before mounting the parts. calibration voltage divided by the A.h capacity of the battery. This means that if the battery is discharged at the same rate as its A.h capacity, the meter would travel over its full scale in one hour. The wattage rating is equal to the maximum discharge current squared divided by the resistance of the shunt. For the "Pacer" mode, RSHUNT is calculated by selecting an optimum discharge rate for the battery. This is the discharge which will provide the racing vehicle with just sufficient battery capacity to finish by the end of the race. Any more and the battery will go flat before the end of the race; any less means that the car could have been driven faster. The value ofRSHUNT for the "Pacer" mode can now be calculated by dividing the calibration voltage by the optimal discharge rate. The wattage rating of the shunt is equal to the maxi- mum discharge rate squared divided by the resistance of the shunt. Once the shunt value has been calculated, you can decide on what to use for the shunt. In low current applications, you can use a standard resistor (eg, 0.H2). This can be installed in the RSHUNT position on the f..~ .l CLASS-2.5 MU -45 Fig.8: if you are using an MU-45 meter, this full-size artwork can be used to replace the existing scale. PC board, as shown in Fig.5. For heavier current applications, a shunt made up using a short length of enamelled copper wire may be more practical. In this case, the shunt must be mounted outside the case (preferably adjacent to the load) so that the heavy current flows directly through the shunt to ground. The VRSHUNT input to the circuit is then simply a voltage sensing connection between ground and the top of the shunt. Table 1 gives details on standard gauge copper wires, their resistance in milliohms per metre and the nominal current rating. For higher current shunts , you will need to use copper bus bar (use manufacturers' data sheets for resistance and current rating details). Once you are set up with a suitable shunt, any final adjustments (if necessary) can be made using trimpot VRl. SC ]UL Y 1991 33 O ~=~! ~o~:ae _,. 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CARD ORDERS/; ~ _._ 3 left 13· All Hard Disk capacities are formatted. IDE/FDD 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:", ate. if you have an earlier version of DOS. ? '-~ J ~ \ ~ .J/111? ~ »-·· .,},. ":f'' . :r -~ I _, L U _1 I_ILI IJ ,I.I ,. I LI I_ I I_I I I I An error analyser for CD players Here's your chance to put an end to the myths of the benefits of green pens, Sorbothane feet, rotational stabilisers and other gimmicks by building your own CD error analyser which connects to your CD player. This first article gives the digital background to the project. By STEPHEN McBRIDE* Since Philips introduced the first domestic CD player, the CD100, in the early BO's (the first in Australia was the Sony CDP101), many companies have been marketing CD accessory products with claims varying from intriguing to downright ridiculous. To 36 SILICON CHIP make matters worse, the "Golden Ear" brigade has brought new meaning to the use of hyperbole. Many of the big brand names are also just as guilty. In hindsight, I'm sure Philips had no idea just how much their claim that CDs offered "pure, perfect sound forever" would be twisted and used out of context as much as it has been over the past few years. Unfortunately, the unsuspecting public has been the victim of unscnipulous dealers out to make a quick buck from those left starry-eyed at the wondrous new technology of the CD system. There is no doubt Philips, and to some extent Sony, deserve to take a bow for bringing true state-ofthe-art recording technology into the home at a realistic price, despite the rubbishing it got from the analog fans in its infancy. Nor is there any doubt that the technology has improved since its inception. Yet despite the fact it's been in the marketplace for eight years, most people are totally ignorant of how the CD system works. Even if you have no desire to build the unit, this short series of articles will give you a good insight into the principles and operations of the CD system. Why have an analyser? As might have been expected, the article on CD green pens in the December 1990 issue of SILICON CHIP was met with a surge of mail. Testing fancy speaker cables is fairly easy but CD performance enhancers present a pile of obstacles, mainly because they (allegedly) work on the disc itself which operates in the digital domain. Proper CD analysers are complex (read expensive) and it would be out of the question to have one in your house. Well, now there is an easier, more economical alternative with this CD Error Analyser (CDEA) . This project will let you have an "analyser" at a fraction of the cost of the real thing. I say "analyser" because strictly speaking it doesn't give all the information a truP. analyser will, but it is as close as you are going to get without breaking the bank. In any case, the features it lacks are of no practical use to anyone except factory QC personnel. The big bonus is that the project has deliberately been designed to allow connection to most CD players on the market, from the el-cheapos to the big-buck units. This has been accomplished by its ability to be configured to suit the machine it's being connected to. Because there are so many chipsets on the market from various manufacturers, I decided to use one of the most popular sets, the Philips CDx series, comprising the CDl , CDZ, CD3, CD3a and CD'-1 units. (A CD chipset is a group of dedicated ICs intended solely for use in CD players). But it should work just as well on devices produced by other manufacturers. Philips chipsets appear in a myriad ofbrands including Philips (of course), Marantz, Aiwa, Micro-Seiki, Cambridge, Mission, Meridian, Nakamichi, Acoustic Research , Revox-Studer, Ratel, Sonographe and Toshiba. My machine is a 1985 Philips CD304 which uses the CDl chipset and this was used for testing the prototype. The machine shown in the photographs accompanying these articles is a CD104, which is virtually identical to a CD304. Incidentally, these players, as old The CD Analyser is easy to build with most of the parts mounted on two PC boards which are soldered together at right angles. We'll show you how to build it & connect it to your CD player in a future issue. as they are, can still outtrack the majority of current model players on damaged CDs and - surprise, surprise they use a single spot laser, not a 3beamer. In fact, Philips, who invented the CD system, has never used 3-beam footprints in any of their players even though they do in the VLP (Video Laserdisc) system, which is analog. Important points Before beginning assembly, a few pertinent points need to be considered. If you fit the CDEA to your CD player, you will most definitely violate the manufacturer's warranty conditions, hence the player will no longer be covered by warranty protection. So please think carefully about the implications offitting the CDEA if your player is still in its warranty period. Also, despite its ability to be adapted to various chipsets, the CDEA can't be connected to all machines. This is simply because some chipsets don't provide external connection points to the relevant information. For example, the Sony CDXl 125 decoder chip has no external access to the error flags so there is nothing you can do if your machine has this chip fitted. Likewise the Yamaha YM3817 uses multiplexed flags which require precisely, dedicated timebase decoding which kills any hope of having universal connection capabilities. Details of how to determine whether or not your machine can be fitted with the CDEA are given in future articles, so check that you can connect it up to your machine before rushing out to gather the parts. Definitions The following are terms which will be used throughout the following text and which may be new to you. Some are terms used only by Philips while others are common to all manufacturers. Note also that this article isn't intended to be one big plug for Philips, even though at times it may appear that way. But as Philips devices are so widely used and because Philips data is readily available, the choice was obvious. HF: High Frequency signal generated by the photosensitive diodes in the laser pickup assembly. This sig~ nal is a representation of the pattern impressed on the disc's information ]ULY 1991 37 Error analyser for CD players ... layer. A hole or "pit" in the surface scatters light from a semiconductor laser by causing a cancellation effect due to the depth of the hole being 1/4 the wavelength of the laser's radiation frequency. By the time the beam travels to the bottom of the pit and reflects back to the top, it is 180° out-of-phase with the light reflected off the area around the pit, which causes a cancellation effect. The flat area between the pits, called "lands", reflects a much larger percentage of light back to the photodiodes. A binary "1" is represented by the entry or exit edge of a pit while a binary "0" is represented by the flat area of the lands or the bottoms of the pits; ie, an NRZ (Non Return to Zero) code is used. HFD: HF Detector; a circuit which monitors the HF signal level and produces a signal, usually binary, flagging whether or not the HF is of sufficient amplitude for the decoder to work. A dropout will cause a temporary loss of HF level, causing the HFD to flag the event. HFD is also referred to as HFL. DROPOUT: A temporary, unwanted interruption to the HF signal caused by foreign matter on the disc blocking the light path (ie, dust or fingerprint), or by a physical defect such as a scratch on the disc surface or a hole in the reflective layer. It can also be caused by a loss of tracking as occurs while searching for a specific track (ie, in cue/review mode). The Philips specifications state that the CDs CIRC standard error correction can completely correct for loss of up to 4000 consecutive data bits (2.5mm on disc) and cope with the loss of up to 12,300 consecutive data bits (7.7mm of disc track length) by the use of linear interpolation. INTERPOLATION: The process of making a mathematical guess for the value of a missing or corrupted piece of data by averaging the values immediately before and after the bad one. For example, for the data stream containing values 1,2,?,4,5, the average of 2 and 4 is 3 and this is used to replace the"?" value. Since audio waveforms are sinusoidal in nature, interpolation provides a close approximation of the original value and hence a small, a 38 SILICON CHIP temporary increase in harmonic distortion. However, this is much better thaQ no value at all which would produce an annoying click. PCM: Pulse Coded Modulation. A system of representing analog signals with a binary weighted digital equivalent. Virtually, all A/D converters use some form of PCM as the digital output, either serial or parallel. The system was first proposed by Nippon Columbia, Japan (Denon). For the CD system, the code is in two's complement form. SAMPLE: A sample is two 16-bit PCM codes, one for left and one for right, representing the value of the original audio signal that was present at the input to the AID converters at the time of sampling. In the CD system, the AID samples are taken every 22.68µs, giving 44,100 samples per second, per channel. This value was mathematically chosen to satisfy several critical requirements. SYMBOL: Eight bits of audio data. Each sample of audio is represented by a 16-bit PCM signal which is split into upper and lower 8-bit halves, known as "audio symbols" for ease of handling. One sample period produces four symbols, two left and two right. EFM: Eight-to-Fourteen bit Modulation. Converts 8-bit symbols into a uniquely mapped 14-bit equivalent, specially chosen to make the decoding circuit as simple as possible for its 256 possible input combinations. EFM ensures there is always at least two '0's between consecutive 'l's but no more than 10 consecutive '0's in a 14bit EFM word; ie, under EFM, 00000000 becomes 01001000100000, 10001000 becomes 01001001000001 and 11111111 becomes 00100000010010. EFM prevents the data stream from containing low frequency components which could interfere with the focus, disc rotation or linear tracking servo systems. Also the code 100000000001000000000010 is the frame sync signal which contains 10 consecutive 0's so EFM prevents false sync triggering. The servos operate in the range 020kHz and the information transmission is in the range 20kHz-l.5MHz. It can also be shown that EFM enhances tracking performance over fingerprints, etc. MERGING BITS: A 3-bit block inserted between two adjacent EFM data words to ensure the 2-10 0's rule isn't violated at the block boundaries. A transition can be inserted if required to control the DC content of the HF signal. The merging bits contain no audio information and so are discarded by DEMOD during decoding. CHANNEL BIT: is a binary digit which has undergone sufficient processing to enable it to be ready for recording on the disc. C&D: Control & Data bits. Used to provide the servo and user-interface microprocessors with information about the current track number and title, the total and elapsed playing time, artist's name, album title, etc. The output is referred to as "Subcode Data" and is in eight serial bits, titled p, q, r, s, t, u, v & w. Each of the eight bits then forms part of an 8-bit parallel data stream by using a serial to parallel shift register. The eight bits clocked in serially are clocked out simultaneously (ie, in parallel) into eight separate serial shift registers, one for each bit, as each new 8-bit C&D symbol arrives. Once a sufficient number have been obtained, they are clocked out as eight individual serial channels titled p-w. Hence, the eight individual serial channels form one multiplexed serial channel during encoding, and decoding produces eight separate serial data channels. The "p" or "pause bit" is reserved to mark the silent periods between tracks, while the q or subcoding bit is used to form a serial information stream for the control microprocessor. Most machines ignore the r, s, t, u, v & w bits as the "q" bit contains the most commonly used data, such as time, track number etc. FRAME: A frame contains six sampling periods; ie, six left and six right 16-bit audio samples. This gives a 32bits per sample period or four symbols of 8-bit audio data. Hence, each frame contains 24 audio sy~bols, 12 left and 12 right, or 192 bits. Each symbol is then interleaved by the rules of CIRC. To this, one C&D symbol (eight bits) and eight parity symbols are added, producing 33 data symbols, or 264 bits. Each symbol undergoes EFM conversion and has three merging bits HIGH FREQUENCY LEVEL DETECTOR DATA SLICER A DEMODULATOR. SAA7010 ~ B : ERROR CORRECTOR . SAA7020 SAA/210. SAA7310 C CONCEALMENT. SAA7000 D : ENHANCED INTERPOLATION. SAA7210 E: TRANSVERSAL DIGITAL FILTER. SAA7030. SAA7120 F: 14-BIT DAC . TOA1540. 16-BIT DAC. TOA1541 G : BIT STREAM MODULATION DAC WITH 156x OVERSAMPLIN G. SAA7 320 H ACTIVE FILTER. TOA1542 OR DISCRETE PAR TS * DEC ODER LO GIC MASTER CLOCK ( 4.2336 DR 11.28~6MHz) CAN SE TIMING AND CONTROL GENERATED IN B. C. E OR G AND OTHERS SLAVED FROM IT AUDIO OUTPUT 8-14 BIT MODULATION AUDIO OUTPU T J~ ___:[___ -- --~L ---"'[__ :!l~~I ___ OUTPUT FLAG SHIFT REGISTER PROCESSOR SU BC ODE DATA 0 BIT P BI T - - - - - - - - - - - + - - - - - - - t - - - - , SERIAL TO PARALLEL SHIFT REGISTER DE-EMPHASI S 14 OR 16-BIT DAC TIMING AND CONTROL MUTE FROM SERVO SYSTEM CLOCK DATA DESCRAMBLER BIT STR EAM DAC 4-SAMPLE SHIFT REGISTER TIMING AND CONTROL COEFFICIENT GENERATOR RIGHT SHIFT REGISTER " EFAB " DIGITAL MULTI PLIER TIMING AND CONTROL SYSTEM CLOCK MUTE - oodB.- ...._,,_ ATTENUATE - 12aB Fig.1: block diagram of a CD player which uses the Philips CDl chipset. Most of the circuit functions & processes are described in the text. Philips chipsets are used in many brands (see text). ] ULY 1991 39 Error analyser for CD players ... · added, giving 17 channel bits per symbol and thus a total of 561 channel bits. 27 sync bits are then added, producing a total of 588 channel bits. This final result is the "channel bit stream" which is recorded on the disc surface such that a "1" is represented by a pit edge . So, our original 192 audio bits ends up as 588 channel bits on the disc; ie, for every 588 channel bits read from the disc, only 192 are PCM audio code. INTERLEAVING: Prior to EFM conversion, the encoding process interleaves (ie, jumbles up) the order of the data symbo.Is relative to time. To illustrate, consider a timeframe containing seven sample periods: 1L, lR, 2L, 2R, 3L, 3R, 4L, 4R, 5L, 5R, 6L, 6R, 7L & 7R. If this data was recorded serially in this order, a fault causing a dropout of, for example, six consecutive symbols would leave us with 1L, lR, 2L, 2R, 3L, 3R, 4L, 4R, ?, ?, ?, ?, ?, ess. In the CD player, a reverse CIRC operation takes place; ie, de-interleaving. CIRC: Cross Interleaved Reed-Solomon Code. Uses interleaving and two decoders , Cl and C2, to correct errors. The de-interleaving process is performed while the symbols are in RAM. When the data is recorded onto a disc, an encoder inserts parity check blocks so that the Cl and C2 decoders can determine whether or not the deinterleaved data is valid. The interleaving process only serves to scatter any data losses; it can't detect or correct for them. That's where Cl and C2 are used. First, the 32symbol frame is de-interleaved and moved into the Cl decoder where four parity symbols are stripped off and used to generate four error syndromes on the remaining 28 symbols. If there are no errors in C1, the symbols are written back to RAM. If one error is detected, it is corrected, then output to RAM. If two or more errors are detected, Cl flags the incorrect symbols as being unreliable and writes them to RAM for further processing. The 28 data symbols output from Cl are further de-interleaved then clocked into the C2 decoder. C2 strips off four parity symbols to create the error syndromes. If there are no errors, the remaining 24 symbols are written back to RAM and the four symbols used for the parity check matrix are discarded. If there is one error, C2 handles it the same way as Cl. If there are two errors, the flags set by Cl mark the errors and C2 uses these flags and its own error syndromes to create erasure positions to enable correction of two errors, then all 24 correct symbols are rewritten back to RAM. In the case of more than two erroneous symbols in C2 , all 24 are rewritten back to the RAM unchanged and a C2 flag is set to mark these 24 symbols as being unreliable. The data, regardless of whether or not it is correct, is then kept in RAM for a 5-frame duration then clocked out to Virtually, all AID converters use some form of PCM as the digital output, either serial or parallel. ? . This poses the problem of how can we guess what the missing values were. How ever, if the original serial stream is interleaved in the form: 1L, 1R, 3L, 3R. 5L, 5R, 7L, 7R, 2L, 2R. 4L, 4R, 6L, 6R, the loss of six consecutive symbols would give 1L, lR, 3L, 3R, 5L, 5R, 7L, 7R, ?, ?, ?, ?, ?, ?. This-may appear to be no different than before, but when we rearrange the order in the original way we have 1L, lR, ?, ?, 3L, 3R, ?, ?, 5L, 5R, ?, ?, 7L, 7R. This is much better than before and if we now split the left and right symbols apart, we end up with 1L, ?, 3L, ?, 5L, ?, 7L and 1R, ?, 3R, ?, 5R, ?, 7R. We can now use the error corrector's parity matrix to determine the missing values since each missing value is surround ed by valid values. Any values which can't be corrected reliably can still undergo linear interpolation to approximate the missing values. Neither function could be performed without the interleaving proc40 SILICON CHIP the next step in the chain, which in most cases is the CIM. Since CIRC spreads out any errors, most error bursts are fully corrected. DEMOD: DEMODulator. The circuit which takes the HF signal (4.3218 MBits/sec) from the laser assembly's photodiodes as its input and extracts and/or recovers frame and block sync signals, the data and parity symbols, the original bit clock rate and subcoding information for control and data displays. HFD notifies DEMOD of dropouts to ensure stability during periods where there is no HF signal. DEMOD also converts the 14-bit EFM words into 8-bit data symbols. ERCO: ERror COrrector. The circuit which de-interleaves the demodulated data from DEMOD, detects and, if necessary, corrects errors in the audio data stream. If ERCO is unable to correct an error, it outputs a flag, UNEC, to notify any following signal processing devices that the data is unreliable. It also removes any speed instability (ie, wow and flutter) by using RAM to buffer the incoming data rate from the outgoing data rate, thus allowing the output data to be re-synchronised to a clock signal derived from a quartz crystal oscillator. Hence, wow and flutter is eliminated. In most cases, ERCO also generates a motor speed control line; ie, MCES (Motor Control from Erco to Servo). The output from ERCO is the left and right audio data in 16-bit serial fashion, and any error flags resulting from the CIRC process not being able to fully correct any errors. UNEC: UNreliable data from Erco to Cim. A flag which signals that the current audio symbol has failed to pass the full requirements of the CIRC error corrector and thus needs further processing before being passed to the DI A converters. In some implementations, UNEC can be used to notify CIM that there will be a symbol arriving five frames later which is corrupted, hence giving advance warning that action will need to be taken. More about this in CIM (below). CIM: Concealment by Interpolation and Muting. If ERCO can completely correct all audio data, CIM is transparent to the data stream. If ERCO can't correct a single symbol (ie, a bad symbol has a good one either side), CIM will use the principle of linear interpolation to replace the error. If the error exists in two or more The CD Analyser is connected to the CD player via this small interface board. Note, however, that the unit can not be connected to all machines. consecutive symbols, the device mutes them until valid data is again available. UNEC gives CIM five frames advance warning when a mute is needed. When CIM receives a MUTE command, either via ERCO 's UNEC or from the control microprocessor, it immediate! y starts a digital attenuation process whereby the audio data values are brought to zero by following a cosine curve (0 - re) over a 30-symbol period and holds the audio values at zero so long as MUTE is active. When MUTE is released, the audio symbols are returned to their normal values (ie, the attenuation is removed) over a 30 symbol period, following a cosine curve (re - 2TC). This action occurs when track jumping is expected by the control microprocessor or when ERCO is unable to correct a burst of errors, there being too many for the interpolator to handle. This smooth muting action prevents annoying and potentially dangerous (to speakers) transients from occurring. Because it takes 30 symbols to reach the zero point, ERCO keeps all audio symbols in a 5-frame (ie, 30 symbol) delay before sending them to CIM. If ERCO decides muting action is needed, the delay line allows ERCO to give CIM a 5-frame advance warning so that CIM will have time to acli vale the digital attenuator down to zero by the time the erroneous data reaches CIM's input. Unfortunately, not all manufacturers' devices offer this critically acclaimed feature. EFAB: Error Flag from A-chip (SAA7210, SAA7310) to B-chip (SAA7220). EFAB is almost the same as UNEC except it only flags current symbols as being unreliable. It doesn't need a 5-frame advance warning because the SAA7220 (B-chip) has internal delay facilities to cope with large error bursts. FCO: Focus Control 0, one of three focus states for the servo microprocessor. FCl and FC2 are used to move the focus lens up and down during the startup procedure by the servo microprocessor. When FC0 is high, the focus and disc rotation servo circuits are overridden and forced off, making the focus lens sit in its home position and leaving the disc stationary. Upon receiving a startup corn- mand from the control microprocessor, the servo microprocessor uses FCl and FC2 to determine if focus can be achieved, indicating that a disc is on the turntable and is the right way up. Once satisfied all is well, the servo microprocessor releases FC0 (ie, it goes from a high to a low), allowing the focus and disc rotation servos to do their thing. It also gives the disc motor an initial shove to help get things up and running as quickly as possible. FC0 only creates a falling edge at startup; ie, an ideal time to reset the counters. RD: Ready Signal. A flag set by the TDA5 708 photo diode processor to signal to the control microprocessor that the laser startup routine has successfully been completed. We can use it for the same purpose as FC0. On the TDA8808, the RD pin is combined with the Si (attempt Startup routine instruction) input. This input is a 2way communications line between the control microprocessor and the TDA8808 and serves fine for use as a counter reset command line (ie, the same as FC0), even though it performs additional tasks. On the TDA8808, it's called Si/RD. 'MUTE: As the name implies, a signal from the control microprocessor (to the CIM) requesting that the audio output signal be muted. This occurs when the control microprocessor expects corrupted audio information to be received by the decoder, such as happens when in the pause mode or others such as skip, etc. The SAA7220 has a similar input: MUSB (MUte from Servo to B-chip). See also ATSB. ATSB: ATtenuate command from Servo to B-chip. This line is used by the control microprocessor to force the SAA7220 to digitally attenuate the audio signal by -12dB. This is so you can hear where the laser is in the high speed searching mode, enabling easier location of the desired portion of the disc. The SAA70x0 (CDl) devices don't offer this facility. In this project, if the SAA7220 is fitted, it is necessary to tap into both MUSB and ATSB, ·as errors are produced when either line is pulled low. In the next article, we will go on to describe the CD chipsets and present the circuit of the CD Error Analyser. * Stud. I.E. Aust; Dept. of Electronic and Computer Engineering, James Cook University, Townsville. sc JULY 1991 41 ;jf\ \, \\\ \-,.\ u ,.~~ ~ ,"1i ri~)' . \,0-- ~, ~ ~ .cc::7 ' ,. , IR~\ ~~/ \ ol? A 1,1,,; .'- ;>,, ~ RITRON Qr-U_AL _ I_T_Y__ RI _T ------. RON POWER ·"" - . :~ c~;N,?.,"! ~: ;!!~i!, ! df: .' '• ;~ j '~ 1 MEG RAM EXPANDABLE TO 4 MEG 16Mhz LANDMARK SPEED TEST 1.2M JAPANESE BRAND F.D.D 42M HARD DISK DRIVE 28m s AC CESS 101 EXTENDED " CLICK " KEYBO ARD JAPANESE KEYBOARD SWITCHES MINI CASE & 200W POWER SUPPLY 256K VGA CARD SUPA VGA COLOUR MONITOR (1024 x 768 res) SERIAL, PARALLEL, GAME PORT 3 YEAR " AUSTRALIAN" PARTS & LABOU R WA RRANTY DOS 4.01 G.W BASIC. 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A10030 ........................ $6.99 FREE CATALOGUES STILL AVAILABLE! COME ON IN AND PICK ONE UP! ◄ SERVICEMAN'S LOG Bits & pieces - odds & ends Yes, it's a bits and pieces month this month. No very profound or heartbreaking technical stories; just a few short ones from which useful lessons were learned and which are worth passing on. The first one did not involve any deep mysteries in the technical sense, but there are a couple of other factors which I feel justify its telling. One of these is the fact that, these days, the problem is relatively rare; the other is that the actual fault is even rarer. As a result, I found myself recalling how I tackled this problem in the early colour days, which led to the idea that a bit of a brush-up in print might be a good idea all round. The set involved was a National TC-1807, a 46cm colour set which belonged to a local motel. And as is often the case with motel installa- tions, there was some suggestion that the fault had been in evidence for some time before it was reported. Guests who stay for only one night seldom report minor problems. Some do not even turn the set on or, if they do, they tend to accept what they get, as long as it talks and moves. Significantly, in this case, the fault was reported by a guest who had booked in for a longer period. And it was, simply, loss of colour; intermittently in the broad sense but often present for hours at a time. In fact, by the time it landed on my bench it had become permanent, a condition for which one is always duly thankful. Mental check list 5E::'RVtCi;;::l\J\/\N AB0UT"f'O t-'c/W(; Pt 'STAB AT l t 44 SILICON CHIP This was when I began recalling my mental check list of possible causes of this condition and the routine for checking them . In one sense, this was easier in early colour sets with discrete components than it is with some modern sets using multi-purpose ICs. But, regardless, there are several fundamental checks which one should strive to make. The first and most obvious is whether there is a video signal, car- rying the chroma information, entering the decoder. Next, is the 4.43MHz crystal controlled reference oscillator functioning? And, at a more subtle level, is it on frequency; ie, within locking range of the burst? This latter fault would be very rare but it has been known to happen. As for the burst itself, this should have already been observed when confirming that there is signal entering the decoder, ideally from a colour bar generator. But the mere presence of the burst is not enough. There is a gating pulse, derived from the horizontal scan frequency, which admits the burst to the crystal phase comparator at the appropriate time. No gating pulse, no burst; no burst, no colour. Another source of trouble is the colour killer. This is designed to block off the chroma circuitry if there is no chroma information, in order to present a monochrome picture free of chroma noise. And, of course, if it kills when it shouldn't, there's no colour. Next there is the half line (7.BkHz) switch, which is used to reverse the reference oscillator phase to the R-Y demodulator, synchronously with the phase reversal introduced at the trans.mitter. Not all receivers respond in the same way to a failure here. In most cases there will still be colour - of a kind - but exhibiting pronounced venetian blind effect. But in some sets it will kill the colour completely. And that's about it. Of course, it is one thing to nominate these sections; it is often a good deal more difficult to pinpoint them, particularly in a modern set with which one is not familiar. In most cases, they will all be contained in a single decoder IC, making access to the actual circuitry impossible. But this is less important than finding and checking the various signals fed to it; eg, the video signal, the crystal reference oscillator signal and , L602 TLK68057 R626 IQK C5i! J., ~R608 0.01 : R625 120 ($ j'330 ~ ,i,, C0-51 C625 50V3.3 C0 -53 VP SYNC f!II C0-:1 "·p :2'1 DbOI DbOZ iCHROMAI ,..-'M-, '-----+-t---iH DblO CL!' _iMAIII 4--------. MA, III.~ ; .. ·w • ~wv-:: ::: c,~1 ),oq •.m. m 5011 -~Albl roo TNP65475AA §)BOARD Fig.1 the relevant portion of the decoder ("B") board, showing IC601 (centre) and the input plug, CO-53, at bottom left. Most of the tests were made around these two units. the burst gating pulse, to name just three. Signal checks So much for the background. With the set on the bench, a perusal of the manual pinpointed the decoder section as being on the "B" board, designated TNP65475AA. This consists mainly of two ICs: IC301 (AN5610N) and IC601 (AN5620N). The latter IC, together with its associated circuitry, performs most of the functions mentioned in the above check list - see Fig.1. I fed a colour bar signal into the set and made my first check at pin 1 of plug CO-53 (lower left), the point of entry for the video signal. All was well here - staircase, sync pulses, burst pulse - and I moved on to the video-in point of IC601 (pin 1). All was well here too, thus clearing the intermediate components, including transformer T601. The next check was at pin 15 of IC601, the entry point for the sync signals (which carry the 10-cycle reference burst), and which come into the board at pin 4 of plug CO-53. (The burst is separated from the sync pulses inside the IC by the burst gate pulse, which is timed to open the gate for the appropriate period). All was correct here, also. OK, what about the burst gate pulse? This comes in on pin 3 of CO-53, and enters IC601 at pin 7, via a rather circuitous route. A quick check with the CRO cleared this. And that, at least at a preliminary level, left only the reference oscillator. This involves pins 12 and 13 of IC601 and consists of the crystal, X601, and capacitors C622, C616 and C617. Again, the CRO is the logical test instrument. Not only will it confirm oscillation but also the amplitude and, with some effort, the frequenc y. A good frequency counter, if available, is a better device for this latter test, assuming a frequency error is suspected. Not that it was necessary in this case. The CRO told the whole story; no oscillation - dead as the proverbial dodo. Looking at the circuit I decided that the crystal was the most likely culprit. And since it needed only a few moments to unsolder it and substitute a spare, this was what I did. And that was it; the set came to life in full colour immediately and hasn't missed a beat since - which was something of an anti-climax I suppose, after all the mental effort that went before. But I don't feel it was wasted; it was a useful refresher course, for me at least. The reluctant Sharp The next story concerns a Sharp 48cm colour TV set, model CX2048. This is a relatively recent model, probably about four years old. The complaint was a little unusual; it was to the effect that if the set was simply switched on and left running, it would run indefinitely - for days, if necessary. (From this I assumed that the owner had done just that). But the catch was that, if it was switched off after a brief period - as little as 15 minutes, as I later established - and then switched on again, it simply would not start. And as I also later established, it needed at JULY1991 45 SERVICEMAN'S LOG - CTD least an hour's rest before it would come good. There seemed little doubt that it was a thermal fault of some kind which involved the starting circuit in the power supply. But I was faced with the problem of not having a manual, or even a circuit. And these things are not always available on demand. However, perusal of the power supply section revealed the presence of an IC with the type number IX0512CE - at least, that's the Sharp designation. Fortunately, I r.13cognised it by what might be termed its generic type number: STR41090, an IC which, among other things, features a starter mechanism. Which brings me to the first point of this story. Sharp - and some other makers - make a habit of this; taking a standard component and changing its generic type number to one of their own. I won't dwell on the philosophy behind this but it can mean that the generic version costs less than the special version. There can be other differences too, which I will expand on later. There have been a number of cross references published, listing these special/generic combinations, many of wpich I cannot recall off-hand. But one I do recall was by TESA (Television & Electronic Services Association Pty Ltd, 245 Rainbow Crescent, Coogee, NSW) and, in particular, the issue for October 1989. Anyway, having established that much, my attention was drawn to two components: a lµF 100V electrolytic capacitor and a 4.7kQ 0.5W resistor in series. This RC circuit was connected to pin 5, which I knew to be the pin for the starter circuit. My suspicion, while somewhat speculative, was further supported by the general suspicion most of us entertain concerning low-value electros. As it transpired, my suspicion was fully justified - well, sort of. So I changed them, even though superficial tests revealed nothing wrong. The trouble was, it didn't work. So I was back to square one and, without at least a circuit, in a pretty hopeless situation. Help sought At this point, it occurred to me to contact a colleague in a distant sub- urb, who is something of a Sharp specialist. Perhaps he knew the answer but, in any case, I could put the bite on him for a copy of the circuit. So I rang him and outlined the problem. His answer was immediate. "The one mike electro and the four point seven 'k' resistor to pin 5 of IC701 change them". "I already have. It didn't do any good", I replied. There was silence at the other end, so I went on, "Could it be a faulty IC?" "It could be, I suppose, but I've never had one. It's always one of those two components - usually the electro. Not surprising really, considering how close it is to the heatsink". And that raised another point which I will deal with later. By this stage, there wasn't much more my colleague could suggest but he did offer to send me a copy the circuit. Well, that was something. And he was as good as his word; the circuit turned up in the next mail. Not that it helped much really, except to clarify the arrangement in my own mind. The two components I had replaced were C711 and R708 and, as my colleague had already suggested, the IC was IC701. I went over the circuit seeking fresh inspiration but found none. So, after a few routine checks I plumped for the :,, WOUL.P YOIJ, UH, L-IKG: ,--o s~e MY He:-Ai"'SIN ' W/;Ll.. AWA OM 46 SILICON CHIP TETIA TV TIP AWA AV-11 Thorn TR101 video cassette recorders. Symptom: The most obvious symptom was that the clock would not run. It could be set, and the counter would work, but the clock would not advance. A secondary fault was that the set would sometimes not switch on. Cure: IC 8AO, an M558858 micro processor that controls the timer was faulty. The uPC runs the clock and counter, and also controls the power on and off for use with the timer record mode. (There are two ·'M558858 uPC's in this model. The timer one carries the suffix -615P). 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. IC. I put one on order (the STR version), it arrived in a few days, and I fitted it. Over the next few days I put the set through as many variations of the onoff cycle that I could think of and it never once failed to start. So it was . returned to the customer and, at last check, is still performing faultlessly. But the second point to be raised about this set - prompted by my colleague's remark - is really one of design. Why is that lµF electro mounted in such close proximity to the heatsink carrying the IC107? These small value electros are notorious for their tendency to dry out prematurely, so why aggravate this by turning on the heat? Nor is this a one-off situation, as I will demonstrate later. Another Sharp In fact , this story reminded me of the next one, which happened some time ago, and which was similar in many ways. It was another Sharp, a 63cm up-market type with stereo sound, type DV-6384. The main symptom was similar; intermittent failure to start but, in this case, apparently not temperature dependent. The circuit is quite different, using an IC designated by Sharp as IX0308CE but also available under the generic type number, STK7310. (There's another story about that too, which I will detail later). Perhaps coincidentally, it is also designated as IC701. In this case there are several electrolytic capacitors associated with the IC and, as before, they are mounted in close proximity to the IC heatsink. And, acting on the advice ofmy aforementioned colleague, I simply changed them all. That seemed to fix it, at least to the extent that I could test it in the workshop . So it went back to the customer and all was well for several weeks. Then it was back with the report that it was still faulty "occasionally". This time I plumped for the IC more in desperation than anything and that did fix it. I still have a suspicion that there were two faults; a faulty electro and a faulty IC. Be that as it may, I still feel that the placement of those electros represents poor design. And that thought takes me back still further. This same set, a couple of years earlier, suffered from a form of foldover, whereby all the text and other rubbish in the horizontal blanking period was running across the centre of the screen. I made a couple of tentative stabs at it but to no avail. I spoke to the Sharp service department twice about it, but none of their suggestions helped. So rather than waste more time, I turned to my Sharp specialist colleague on that occasion also. "Ah", he chuckled, "that's easy" (yeah, easy when you know how). "It's in the vertical output stage; transistors Q501 and 502. Change all the electros around these". And he was right. I changed them and that fixed it. But the real point about the problem, as he pointed out at the time, is the mounting of the electros. Each of these two transistors is mounted on the bottom of a fairly large U-shaped heatsink, the two heatsinks being mounted side by side, with about 25mm between the upright sections. This is fair enough in itself, but there are also some six or seven electros mounted in the vicinity; some actually inside the heatsinks and several in the 25mm space between them. It's little wonder they pack up. In fact, my colleague suggested that I follow his practice and relocate the electros under the board, well away Australian Made TEST EQUIPMENT YOU CAN TRUST SHORTED TURNS TESTER Built-in Meter to check EHT transformers incl uding 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 A/C 2.2 amps. Just about as important as having a soldering iron in your toolbox! $75.00 + $10.00 p&p HI-VOLTAGE PROBE Built-in meter reads positive or negative 0-50kV. For checking EHT and focus as well as any other Hi-tension voltages. $98.00 + $5.00 p&p REMOTE CONTROL TESTER (INFRARED OR ULTRASONIC) Designed to test lnfrared or Ultrasonic control units. With the extension lead you can also test infrared units which cannot be placed in front of the testing unit. Requires a 9V battery. Output is via the LED diode and piezo speaker. $85.00 + $4.00 p&p LASER DETECTOR PROBE A new addition to the remote control tester. Comparable with units costing $500 or more. You can test the laser pick-up in compact disc players. $27.00 + $2.00 p&p NEW PRODUCT TEST TUNER Save time and money with this tester. Helps you determine if you have a tuner problem, an AGC problem or a fault in the IF stages. $250.00 (Tax inc.) TUNER REPAIRS from $17.00 exchange + p&p Cheque, Money Order, Bankcard or Mastercard -a;v. TUNERS} .·.·-•-•.•.·.·.·.·.--·-·-·-·-·-·.-.·.·.·.·-·.·.·.·.·.·.•.•.·.•.•-·.·.•.•-·,:'.:-:-:-· 216 Canterbury Road, Revesby, NSW, AUSTRALIA, 2212 ~ (02) 774 1154 '~ (02) 774 1154 JULY 1991 47 SERVICEMAN'S LOG - CTD from the heatsink. I followed his ad vice and there has been no sign of that problem since. Part numbers Now, let's go back to the matter of special/generic type numbers and, particularly, the IX0 308CE/STK7310 combination. The STK7310 is in fact an upgraded version of the original IX0 308CE w hich had a nasty habit of developing an internal short circuit. As I can personally testify, the resu lts could be catastrophic. I have encountered two DV-6384 sets (one is still in my workshop) which were total write-offs after such fai lures. Apparently, protective circuits in these sets couldn't act fas t enough and the breakdown took out ICs and transistors left, right and centre. The estimated cost of repairs were such that the owners couldn 't consider it. From time to time I have considered trying to salvage the set in the workshop, on a purely personal basis. But when I think of the many hours of work involved and the cost of the replacement parts, I tend to back off On the other hand , it could make a good source of spare parts - those that have survived, that is. In fairness, I should add that these two sets were early production models and I have no doubt that later models used the upgraded IC , regardless of the type number it carried. Believe it or not To round off, here is the you wouldn 't-believe-i t story of the month. From time to time, I have chronicled the weird assortment of foreign objects that I have found in video recorders; coins, match sticks , parts of children's toys, dead spiders - to name just some. But I reckon this one beats them all. Readers may recall that I have a friend who, as well as keeping his own assortment of TV sets in running order, sometimes helps out a friend or neighbour on a purely non-professional basis (s ee April 1990). Such a situation arose a few months ago when a fri end asked him to have a ~.RADIO PTY. LTD .la1S~.r.~1;r.:.i;: RCS Radio Pty Ltd is the only company which manufacture s and sells every PCB f., front panel published in SILICON CH IP, ETI and EA . 651 Forest Road, Bexley, NSW 2207. Phone (02) 587 3491. 48 SILICON CHIP look at his colour TV set. It was a German make , a Gratez , which ap peared briefly on the Australian market with the introduction of colour. Since he had another set, he was happy for my friend to work on it on a "when y'got time basis". Which was just as well, because it needed a fair amount of work plus some spare parts which had to be tracked down. Anyway, the job was eventually completed and the set returned to the friend and set up in the lounge room. It turned in an excellent performance and everyone was delighted. Then came anoth er request. The owner had a video recorder which was normally used with the set but which had been put away in a cupboard while the set was being serviced . Would my friend supervise the various cable connections necessary to get the recorder back into operation? "Of course, no problem". But there was a problem. When all the necessary connections had been completed and an attempt made to play a tape, it simply wouldn 't work. More precisely, it wouldn't accept the video cassette. So my friend grabbed the appropriate screwdriver and whipped the cover off. And what did he find? During the storage period a colony of ants had found their way into the cupboard and then into the recorder. And they had built a substantial nest in the mechanism, consisting mainly of eggs and, of course, the ants themselves crawling all over them. After the initial shock came the important question as to how best to tackle the problem. A brute force approach did not seem to be appropriate, since there was a risk of adding to whatever damage might have been done already. So my friend simply took the recorder outside and sat it in the Sun for an hour or so. And that was the best idea. The ants didn't like the change of venue and proceeded to methodically remove themselves and the eggs as only they knew best. Finally, when the site had been abantloned, my friend carefu lly cleaned out what little rubbish remained, examined the mechanism for any signs of damage, found none, and tried the recorder once more. And it worked perfectly, first time; which was nearly as big a surprise as finding the intruders in the first place. But at least it was a happy ending.SC n vr,m..,.:, 1H l::Ll::C I HONIC S JAYGAH t.Lt.G 1 HUNlCS JAYCAH t.Lt.C I HUNIC:::i JAYCAH t.Lt. L I HUN IC;:, JAYl,AH t:.Lt:.V I HUN IV.:J .JA.TVAH CLCV r MVl'llV.::> .J M 1 ,R 1R •.R 1R JAYCAR JAYCAR JAYCAR JAYCAR ELECTRONICS ELECTRONICS ELE CTRONICS ELE CTR ONICS 1 1\\11"'/'l n ,-, r.r T.n..r.:,,~, ,,....,e, ELECTRONICS ELECTRON ICS ELECTRONICS ELECTRONICS \R E.LECTRC-"'-1re ,R ELEC TR q ,R ELECTR~ ,R ELECTRC ,R ELECTRC ,R ELECTRC ,R ELECTRC ,R ELECTRC ,R ELECTRC ,R ELECTRC ,R ELECTRC ,R ELECTRC H ELECTRC ,R ELECTRC ,R ELECTRC ,R ELECTRC ,R ELECTRC ,R ELECTRC ,R ELECTRC ,R cLECTRC ,R ELECTRC ,R ELECTRC ,R ELECTRC ,R ELECTRC ,R ELECTRC ,R ELECTRC ,R ELECTRC ,R ELECTRC H ELECTRO ,R ELEC TRO ,R ELECTRO ,R ELECTRO ,R ELECTRO ,R ELECTRO ,R ELECTRO ,R ELECTRO ,R ELECTRO ,R ELECTRC ,R ELECTRC ,R ELECTRO ,R ELECTRO ,R ELECTRO ,R ELECTRO ,R ELECTRO ,R ELECTRQ ,R ELECTRO ,R ELECTRd ,R ELECTRC ,R ELECTRq ,R ELECTR~ ,R ELECTRq ELECTRONICS ELECTRONICS E1_ECTRON ICS ELECTRONICS .'.f)Vr,-..o -~ -I )::: l"'T p r, 11.11 r c- JAYCAR JAYCAR JAYCAR J AYCA R ELECTRONICS ELECTRON ICS ELEC TR ONICS ELECTRONICS I /'l\/,.... ,~~-.I:::J . r-';"Tn,....,~ 11 rc- JAYCAR JAYCAR JAYCAR JAYCAR ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS JAYCAR JAYCAR JAYCAR JAYCAR I /'IV,.... l\ n ,- , r-r Tn ,....,~ 1, r e- ELECTRON ICS ELECTRONICS ELECTRONICS ELECTRONICS ' " " r "n ,-, ,-,-, -r r,,-..~ , ,,... ..... JAYCAR JAYCAR J AYCAR J AYCAR 1 1\\/ r I\ r"l ELECTRONICS ELECTRONICS ELEC TRONICS ELEC TR ONICS ,- , r- rTn,....,,.,1 , re- ECONOMY WIRELESS SECURITY SYSTEM Al last, you can now install your own wireless burglar alarm and ii won't cost you and arm and a leg! The new EG100 Is made by Zeus, the same people who make our current wireless system. In fact, all the same wireless extras will workwllh this panel. The EG100 Is a key operated single sector panel which accepts not only the wireless PIR's etc, but you can hard wire detectors as well. For example 2-wlreless PIR's, 2wireless door/Window transmitters and awired PIR will all work very happily on the one sector. This is the IC1Nesl priced wireless panel we've seen that is TOP OUALITY. l;here are plenty of junky ones around that we Just won't sell. After all -.a burglar alarm that false triggers Is no good to anyone! FEATURES • Low cost • DIY Installation • Accepts wireless and wired sensors • Tamper proof protected • LED indicators • Keyswilch arming wllh exll delay time • Instant alarm when sensors triggered • NC and NO relay output SPECIFICATIONS • Operates on 303-875MHz • System codes 4,096 • Transmitting range 50 metres (open space) • 30 second exll delay• Instant enlry delay Accessories • Back up battery 1.2A 1'2>/ Cat. SB-2480 $26.50 • Wireless passive Infra red detector Cat. LA-5205 $129.95 • Door/Window reed switch Cat. LA-5210 $69 • Siren 1'2>/ DC Cat. LA-5700 $28.50 • Strobe light Cat. LA-5300 $32.95 • Wired PIR's from $59. Cat. LA-5202 Includes 240V PC7tYer supply ~ ~ $229 SOLAR PANELS Firstly, Jaycarwish to apologise for the long delays In getting the solar panels featured In our catalogue into stock. We won't begin to explain the huge quality control problems we have had. We have since found new suppliers and we expect to have two new model s this month and three new models next month. Please bare with us, as the delays will beworthwhile. AVAILABLE THIS MONTH 12V 8 watt PANEL ':': ) { f C: L C:V t nv1'111...,v uM r vnr, .._ .__.._ .._,, , ,....,, ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS JAYCAR JAYCAR JAYCAR JAYCAR , ,.v,.... l\r"l ,- , ,,....,..,.,,....,~ ,,,...,e. 1 1\ \/ f"'I\ C ELECTRm ELECTROr ELECTRm. ELECTRm,, c:r c:.,;-.rROt. / } } \ } ( CORDLESS TELEPHONE BATTERIES Don't pay huge amounts of money for your replacement NI Cad batteries for your cordless telephones when they die! Jaycar now stocks the three most used battery combinations. Top quallly batteries supplied. / . ,~ CTB4 ...._ ·7 ~-- '..· . · ' . ·--· ··;,.;,,.,..~ $22.95 Nominal voltage 3.fN Nominal capacity 280mAH Cat. SB-2474 $16.95 CTCS $32.95 {SCOPE 20 WATT SOLDERING IRON NEW LOWER PRICE • ONLY $119.95 0.45V 1000mA PANEL ":'. \ ) ~ CTB1 $29.95 CATALOGUE PRICE WAS $ 169 .95 I J ;_..__ ' ..~:'.-.~--.. Nominal voltage 4.8V Nominal capacity 250mAH Used in the ATD MP200 and MP250 telephones Cat. SB-2472 Top quality Australian made scope 20 watt 240 voll soldering iron now available from Jaycar. It incorporates an air cooled finger grip for continuous use. Rated at 270°, 20 watt. CatTS-1490 Spare tlp -2mmflat Cat. TS-1492 Top quality solar panel supplied with lead and alligator clips for output. Aluminium frame, epoxy sealed. Spees: Voc 16V, max 18V. lsoc 400mA max SOOmA. Cat. ZM-9030 $8.95 Ideal for experiments. Connect In series or parallel. Terminal strap enables easy connection to other cells. AVAILABLE NEXT MONTH l / Cat. ZM-9004 AVAILABLE NEXT MONTH IBM PERSONAL COMPUTER UPGRADE GUIDE $24.95 $42.9 5 $75.00 By CSandler and T Badgett Packed wllh upgrade package hlls, misses and preferences, you get expert advice on what to do with your PC. With all the Information this handy text contains, you can even build your own custom design piece-by-piece! This book is an invaluable resource on: • Upgrading advanlages and disadvantages • Selecting hard disk drives and their components• Completing a computer "makeover" Operating system upgrades • Printers and their options • Testing your upgrade system • Plus much more! And ll's all in a "straight-talking", conversational text that's easy to understand. buyer or a veteran computer technician, you'll find this one of lhe most helpful books around. 285 pages, soflcover, 190 x 23Qmm Cat. BS-0740 6 volt 1 watt 12 volt 2 watt 12 volt 4 watt cat. ZM-9020 cat. ZM-9024 cat. ZM-9026 : ~~~g;:gttI!l;=============:::;:::==:zs ELECTRO ELECTRO ELECTRO ELECTRO ELECTRO ELECTRO ELECTRO ELECTRO ELECTRO ELECTRO ELECTRO ELECTRO ELECTRO ELECTRO ELECTRO ELECTRO ELECTRO ELECTRO ELECTRO ELECTRO ELECTRO ELECTRO ELECTRO ELECTRO ELECTRO ELECTRO ELECTRO ELECTRO ELECTRO ELECTRO ELECTRO ELECTRO T VMn JAYCAR JAYCAR JAYCAR JAYCAR .JM Nominal vollage 4.8V Nominal capacity 250mAH Cat. SB-2475 $6.50 10+ $5.85 ea ELECTRoE!;][C:=:=====di,::=======:::::r;; .R .R H .R .R R R R R R R R R R R R R H H H .R R R R R R R R R R R R VAM C L CV I '> :: ~~~g;:2 j ,R ELECTRO ,R ELECTRq ,R ELECTRO ,R ELECTRO ,R ELECTRd ,R ELECTRd ,R ELECTRO ,R ELECTRO. ,R ,R ELECTRO ,R ELECTRO ,R ELECTRO ,R ELECTRO ,R ELECTRO ,R ELEC TR O .R ELEC TRO .R ELECTRO .R ELECTRO .R ELECTRO .R ELECTRO JAYCAR JAYCAR JAYCAR JAYCAR UNDERSTANDING TELEPHONE ELECTRONICS By J Fike & GFriend Electronics Is bringing lower costs and expanded capabilities to telephone communications. This book tells you how. Subjects covered Include: dialling, ringing, transmission, signalling, switching, digital techniques, modems and the new cordless phone technology. It's all here In an easy-tounderstand format, fully Illustrated and Ideal for sell-paced learning, 284 pages, softcover 180 x 230mm Cat. BS-0460 R ELECTR01~1v.:, .JA r VAH t:Lt:V I HUl\llV.:> .JA YV ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR 8....E.LE.C.IB.b.llf'C:. IAVC,ll_Q i:=1 ~ rTA0.~.11rc:: Normally $18.95 THIS MONTH ONLY $9.95 Save $9 Cal PL-0854 ~ Description Price 09 female lo 025 male, 2mt $19.95 09 male to 09 female, 2mt $12.95 Centronics plug to centronics plug, 2ml $19.95 Hi-density 150 male to female, 2mt Keyboard ext 5 pin DIN to DIN BUY 10 OF ANY PRODUCT TAKE 100/oOFF R R R R R ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS Centronics printer lead D25 plug to centronics plug lead -1.8mt $ 39.95 $34.95 - COMPUTER LEAD BARGAIN JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR HOf\ AH t:Lt.C I ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS IAV('AQ c: u;crcor,,ucc: JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR ELECTRONICS ELE CTRONICS ELE CTRONICS ELECTRONICS ELECTRONICS JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS JAYCAR JAYCAR J AYCAR JAYCAR JAYCAR ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS 1.A.V("l\.D_ C I C f'T..C.OP.,.IJ("C_ 1JIVCAP Cl C C T C ~ . C . . A O C:! CCTOOtl!O O JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR ELECTRONICS IJAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICSIJAYCAR ELECTRONICS JAYCAR ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS !AUCAD Cl co:rnoe una.l !I\Vr"'AC C:! CCTOOhllCC' JAYCAR JAYCAR J AYCAR JAYCAR JAYCAR ELECTRO~, ELECTRO ELECTRO ELECTRO ELECTRO l&'fC&O c:i c ;JIGS I JICS I JICS H ICS HICS IJICS JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR ELECTRONICS ELECTRON ICS ELECTRONICS ELECTRONICS ELECTRONICS JAYCAR JAYCAR JAYCAR J AYCAR J AYCAR ELECTRONICS ELECTRON ICS ELECTRON ICS ELECTRONICS ELECTRONICS JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR ELECTRONICS ELECTRON ICS ELECTRONICS ELECTRONICS ELECTRONICS JAYCAR JAYCAR JAYCA R JAYCAR JAYCAR ELECTRONICS ELECTRON ICS ELECTRONICS ELECTRONICS ELECTRONICS JAYCAR JAYCAR JAYCAR JAYCAR J AYCAR ELECTRONICS ELECTRONICS ELEC'T"R ONICS ELECTRONICS ELECTRONICS JAYCAR ELECTRON ICS JAYCAR ELECTRON ICS JAYCAR ELECTRON ICS JAYCAR ELECTRONICS J AYCAR ELECTRONICS ,nr • r~~ ~, .. ~r JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS '"'~• r r , r ~ ~~r, .. rr JAYCAR ELECTRONICS JAYCAF JAYCAR ELECTRONICS JAYCAF JAYCAR ELECTRONICS JAYCAF JAYCAR ELECTRONICS JAYCAF JAYCAR ELECTRONICS JAYCAF , ,.,r,rr• --- ~r ~ • ·cSJAYCAF CS JAYCAF CS JAYCAF CS JAYCAF CS JAYCAF CS JAYCAF CS JAYCAF . CS JAYCAF The cheapest way to make your Industries station .. ····"·· CS JAYCAF vehicle look like you have a burglar has set a new . CS JAYCAF alarm. The pack Includes a120mCd standard In cost ' CS JAYCAF 10mm diameter red LED, and a black CS JAYCAF Pkt 10 1990 Price Cat effective soldering bezel. The 120mCd LED Is as bright CS JAYCAF stations for the $9,50 XC-4730 5.25" DSDD $5.10 as a normal red bezel. Unll requires a CS JAYCAF hobbyist CS JAYCAF 5.25" DSHD $10,50 $ 15,95 XC-4732 14mm hole and simply snaps in. Add or manufacturer. It CS JAYCAF lo lhls acouple of our burglar alarm $15,95 XC-4736 3.5" MF2DD $9.75 features a CS J AYCAF stickers (Cal. LA-5100 95i ea) and CS JAYCAF XC-4738 dial-up temperature 3.5" MF2HD your vehicle looks alarmed for under $8 . S JAYCAF between Cal. LA-5085 CS JAYCAF 315°C - 427°C CS JAYCAF (600°F - 800°F), CS JAYCAF No more constant CS JAYCAF CS JAYCAF to select a S JAYCAF For full specs see the new S JAYCAF Jaycar catalogue. Cat. TS-1600 S JAYCAF S JAYCAF Another surplus bargain. These are aplezo HI Fi lweeler, bul in a S JAYCAF strange shape. They were used in a Kangaroo scaring device, S JAYCAF bul the manufacturers had amodel change and these became S JAYCAF surplus. The speclficallons are similar lo our economy plezo S JAYCAF Another surplus stock buy. This lime a high quality steel box, lweeler(Cal. CT-1905), bul CS JAYCAF which would make agood power supply box or for general kll S J AYCAF the shape is rather different. S JAYCAF work. !I's painted while, has venlilalion slots on lhe lop and SPECIFICATIONS! Ideal for the hobbyist and handyman. Our lowest price 240 S JAYCAF two sides. There is a holeon one end for a mains cable and :~~~response S JAYCAF voll quality iron has astainless steel barrel. 25 wall. cord grip grommel and on lhe other end lwo holes for banana S JAYCAF Cal. TS-1450 lerminals or swilches, elc. Size165(L) x115(W) x 125(H)mm. Peak Power 75 walls S JAYCAF You would expecl lo pay about $25 for this box, bul you can S JAYCAf lnlermillenl S JAYCAf purchase lhese now lrom Jaycar for only $12.95 or a_ boul 1/2 Use wilh or wl lhoul S JAYCAf normal price. crossovers. Size 50mm S JAYCAf Cal. HB-5470 diameter, 60mm mounling···· · S JAYCAf holes, length 75mm S JAYCAf S JAYCAf Including bullet. S JAYCAf Cal. CT-1906 S JAYCAf S JAYCA f ~s JAYCAf S JAYCA f ,S JAYCAf S JAYCAf S JAYCAf S JAYCAf S JAYCAf S JAYCAf S JAYCAf S JAYCAf S JAYCAf JS JAYCAf JS JAYCAf The Maggylamp is awidely adjusted JS .IAYCAF magnifier wllh a12.7cm dlameler biCS JAYCAF convex lens 4.00 dioptres focal length of JS JAYCAf Low cost, high 25.4cm. II ls essenllally a mlnlscope wllh _,S JAYCAF performance llghllng. Maggytamp has flexible arms for J S JAYCAf DMM wilh 12 months JS JAYCAF easy poslllonlng. Handsome, sturdy warranty See catalogue for full details :s JAYCAF conslruclion assures years of service. Cal. QM-1410 cS JAYCAF JS JAYCAF S JAYCAF Cal. CW-2150 ,S JAYCAf :s JAYCAf ,S JAYCAf i ,S J AYCAf :,- ,S JAYCAF ,S JAYCAF ,S JAYCAF S JAYCAF ,S JAYCAF JAYCAF S J AYCAF Sub C NiCads are commonly used in battery ;s JAYCAF packs to power RC racing cars an(;! cordless ;s JAYCAF S JAYCAF power tools. Up til now, if a battery pack failed ;s JAYCAF - you would need to purchase a new pack S JAYCAF from the manufacturer of the product. These S JAYCAF battery packs are very expensive. The most S JAYC AF common voltage used is 7.2 volts which is S JAYCAF S J AY CAF made up with 6 x Sub C NiCads. So, instead Add this on lo your car alarm lo make S JAYCAF of being forced to pay $70 - $100 for a the indicalors flashwhenyou turn your S JAYCAF replacement battery pack, you can now fix it alarm on and off. Suppliedwilh wiring S JAYCAF yourself and save a fortune. The Sub C's are instructions. Wecannot guarantee S JAYCAF supplied with solder tab and are rated at S JAYCAF which alarms this unil will work with, S JAYCAF 1.2Ah. bul al lhe price, buy one and see!! S J AYCAF Cat. SB-2456 Cal. LA-8980 S JAYCAF Assorted LED's Inc. 3 & 5mm in yellow, orange, red & green. S JAYCAF Reclangular, triangular and olhers. All for less than 9t ea! S JAYCAF S JAYCAF 9 S JAYCAF S JAYCAF S JAYCAF , -S JAYCAF JA , CAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICSJAYCAF JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICSJAYCAF JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR-ELECTRONICS JAYCAR ELECTRONICSJAYCAF JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRON ICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELEC rRON ICSJAYCAF JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR t'LECTRONICS JAYCAF ACT DISKS AT EVEN LOWER PRICES CHEAPEST IN AUSTRALIA? 10mm FLASHING LED THE OK SOLDERING f:':~!JgN 1111 Make you r vehicle look alarmed for under $8 }? $24,95 $ 3 4.95 $5.95 $1 59.50 BARGAIN HOBBYIST BOX JAYCAR SOLDERING IRON ■,, , ,• $16.95 ONLY ON LY $2.95 10+ less 10% 100+ $2.00 e a BUILD A ROW OF DIRECT IONAL TWEETERS 20 RANGE DMM ONLY $299 ~ LOCK MOVEMENT NEW SUBWOOFERS 8" 80Wrms ONLY $49.95 $99.50 10" 120Wrms cat cw-2152 $129.50 Sub C NiCad :s BARGAIN LED PACKs Pack of 100 $6.95 ONLY $9.95 sa:95 IICS IICS IICS IICS ICS ••cc lt\\lCAO Cl C C TDObl!CC • IOVCOR Cl CCTP0,. 11f""_C ll\V~~L'TP("\I\JlrC:. 1/\V,...IID r::: , cr- T Of"'\,.._11,-..c, II\Vr-110 Cl Cf" T O("\I\J l rC lf\Vf"/1.0 Cl rrTO("'\l\ll.C_Q___j_l'i.YC_a..Q_r;:1 r::rTPnr-..urc:. llJ. ':YrtJ.A r:: 1 r::rTPr'I/\IJf"C:. lfl\/r-1\r ,K ,R ,R ,R ,R ,R t LtC I KUNIC!; ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS ELECTRC- •-0 ::~~ tEE E Ecgc i ::oc 0 R ELECTRC ~ ~t ~gi~g R ELECTRC R ELECTRC R ELEC TRO ~ ~t~g~g R ELECTRO R ELECTRO R ELECTRO ~ ~t~g:g R ELECTRO R ~LECTRO R ELECTRO R ELECTRO R ELECTRO R ELECTRO R ELECTRO ~t~g~g R ELECTRO R ELE CTRO ~ ~ ~t~gi~g R ELECTRC 9 ELECTRO 9 ~ ELECTRO ~t~g~g 9 ELECTRO 9 ELECTRO 9 ELECTRO 9 ELECTRO 9 ELECTRO 9 ELECTRO 9 ELECTRO 9 ELECTRO 9 ELECTRO 9 ELECTRO 9 ELECTRO 9 ELECTRO 9 ELECTRO 9 ELECTRO 9 ELECTRO 9 ELECTRO JAYCAK JAYCAR JAYCAR J AYCA R JAYCAR • •• • • • - t Ltc; I KUNIC!; ELECTRONICS ELEC TRONICS ELEC TRONICS ELECTRON ICS ••• -----• ••-- JAYCAK JAYCAR JAYCAR JAYCAR JAYCAR • • • •- • - ELtGI RUNIC!; JAYGAR ELE CTRONICS JAYCAR ELECTRONICS JAYCAR ELEC TR ON ICS JAYCAR ELEC TR ONICS JAYCAR -• ---- •• ••• • • • • •- • - ELECTRONIC!; ELECTRONICS ELEC TRONICS ELECTRONICS ELECTRON ICS -· ----- • •• -- JAYGAK JAYCAR JAYCAR JAYCAR JAYCAR ,..,_ • - MS DOS/PC DOS Quick Reference llluslraled Lolus 1-2-3 Release 2. 2 386 compuler Handbook Understanding Digital Troubleshooting Towers Digital IC Selector Towers Microprocessor Selector Towers OP Amp and Linear IC Selector Semicon Trans Index Data and Equip Microprocessor Data Handbook Using Field Effect Transistors Underslanding Compuler Science Applic Digilal ICs Fascinating IC Projects lllustraled Wordslar 6.0 Prraclical Timer Circuils Build Coils and Transtormers Transislors and Thyristors Made Easy Enhanced MS/DOS Balch File Programming Build 80486 PC and Save Bundle 41 Projects Using 741 IC Design Build, Test Speaker Syslems 51 Project Using 4011 IC Relays and Their Applications Simplilied Pracllcal Filer Design uild S~ IBud_el Recording studio We havea quanlily of super high qualily alarm conlrol boxes. They are painled cream and have various holes in lhe panel for LEDs, cam lock, elc. Some have lhe fonl panel printed, some don't, lhe holes vary and lhe size ol the panels vary. The size ol the sample is 330(H) x 230(W) x 85(D)mm, but some are slighlly smaller lhan this. This product is more suited lo the personal shopper who can pick the one most suiled, however, we will ship lo mail order cuslomers upon request. (Cam lock Cat SM·l 029 $9.95. Locking arm may not be correct lenglh in somecases.) Ideal for hobbyisls and installers. Savea bundle. Cal HB-5480 ON LY $24 .95 ea . >'.::::===========; _,... -- . ; ·"""""'' ."' JAYCAR 5MHz OSCILLOSCOPE tL~G I KUN IG!; ELECTRONICS ELECTRONICS ELECTRON ICS ELECTRONICS - • ----- --• -- JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR ' • _,_ • - ELECTRUN ICS ELEC TRONICS ELECTRONICS ELEC TRON ICS ELECTRON ICS r , - - - - - • -- - - Ca!QC-1910 ~ $399 CRO PROBE TO SUIT ~ Probe is identical lo our QC-1900 model 1x, 10x, bul supplied with an adaptor. (BNC socket to two banana plugs.) ~ See catalogue for full specs BM-2110 BM-2112 BM-2116 BM-2416 BM-4558 BM-4564 BM-4557 BM-2342 BM-2340 BM-2438 BM-2420 BM-2442 BM-2443 BM-2118 BM-2436 BM-2440 BM-2426 BT-1318 BT-1320 BM-2430 BT-1322 BM-2432 BM-2428 BT-1326 BT-1 324 $16.95 $24.50 $24.50 $12.95 $14.95 $19.95 $9.95 $19.95 $19.95 $3.95 $12.95 $7.95 $3.95 $29.95 $3.95 $3.95 $14.95 $49.95 $34.95 $3.95 $34.95 $3.95 $9.95 $34.95 $29.95 JAYGAR JAYCAR J AYCAR JAYCAR JAYCAR ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS JAYCAK JAYCAR JAYCAR JAYCAR JAYCAR , . . , _ • - r , - - - - - • -- - - ' ""- •- t Lt C I KUN ELECTRON ELECTRON ELECTRON ELECTRON r , r-TRON atures: ear, month, day and date 12 or 24 hour format daily alarm, 1 calendar alarm 18 world city time dis la s ta bank for 5 bers New design indoor antenna will pick up alrnosl anylhing! Well, almosl! Omni directional and polarised ii will pick up AM/FM/VHF and UHF. Frequency range 100MHz -960MHz. Easily adjusled for horizonlal or verllcal signals - jusl Iurn ii around. Suppliedwilh 12 velccro pads on lhe underside for easy mounting on awall or window. Size 280(W) X 240(L) X12(D)mm. Supplied wilh 3 metres of coax and a slandard 750 TV plug. Cat. LT-3135 Features: • Bandwidth DC to 5MHz (. 3dB) • Sensilivily 10mV/Div • Allenuator 1/1, 1/10, 1/100 • Sweep frequency 10Hz 100kHz 4 ranges• CRT 130mm round screen CRT Cal QC-191 2 $45 ~t~gi~g JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR • • • •- . - +AP'ALANREML BCOOXNTROL •~j§i/11 _:· ·)( Advertised NEWIn May AND BARGAIN BOOKS ..., ,. 1 • 1 ...-, and June. Full delails In lhose ads ~ ~t~g=g 9 ELECTRO 9 ELECTRO 9 ELECTRO 9 ELECTRO 1 ELCCTRO 9 ELECTRO 1 ELECTRO 1 ELECTRO 1 ELECTRO 1 ELECTRO 1 ELECTRO 1 ELECTRO 1 ELECTRO 1 ELECTRO 1 ELECTRO 1 ELECTRO I ELECTRO I ELECTRO I ELECTRO I ELECTRO I ELECTRO I ELECTRO I ELECTRO I ELECTRO I ELECTRO I ELECTRO I ELEC TR O I ELECTRO : ELECTRO : ELECTRO ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS ELECTRON ICS - • ----- • ••-- $ 37.95 SMALL SPEAKERS 100 WATT 12V DC· 240V AC INVERTER Someuniquelealures include: • Low ballery alarm - an audible buzzer sounds when ballery voltage drops to 10.7 volts • Low ballery shuldown - aclivaled when ballery discharges lo 10.0 volts, which prevents damage lo ballery • Eleclronic circuil proteclion - prevenls potential damage from overloads and inadequale ventilation • High surge current capability- starts diflicult loads such as lamps, motors and olher lnduclive loads Cal Ml-5030 $189.50 We had a quanlily of these some lime ago, and we still gel asked if we have any moreavailable. They are used in lelevi sions. They have roll surrounds and are QUALITY small speakers. ELECTRONIC WATCHDOG TYPE 1 IF you are aged or live on your own, owning a dog can ofler you wondertul peace of mind, especially al nigh! from lhe risk of inlruders. There are so many problems associaled wilh owning a dog - feeding ii, caring for ii, walking It, vel bills, who looks aller ii on holidays elc. This product can offer you peace of mind at nigh! wilhoul all the fuss assocaled wilh dog ownership. The eleclronicwalchdog incorporales a microwave motion sensor which activates when ii delecls movemenl and then ii slarls barking. II bark for 5 seconds each lime ii Is lriggered and barks conllnuaily if !here is conslant movement. The sound Is very aulhenllc and would easily scare lhe wits oul of an lnlruder. The unll is housd In a plastic box wilh ahandle on lhe lop. II operales form 240V lhrough a piugpack (supplied) and has a volume conlrol and a range of conlrol. Call inlo any slore lor a demo. Cal LA-5280 Oval speaker, rubber roll surround. Size: lenglh 68mm, widlh 34mm, heigh! 33mm. Impedance 70. Power handling 1 wall. Cat.AS-3020 $ 3 .9 5 TYPE2 Oval speaker, bul wilh 4 holes for slandard lype mounting. Roll surround. Size: length 70mm, widlh 40mm, height 29mm. Impedance 120. Power handling 3watts. Cal.AS-3021 $ 3 .95 TYPE3 Oval speaker wllh 4 holes for mounling. Same dimensions as type 2. Impedance80. Power handling 5 watts. :~t~g;~g Also available 300 and 500 watt models '~t~g;~g1r::r:::::=---------------c::::t<it1 4f : ELECTRO IRELESS RXJTX ELECTRO ELECTRO ELECTRO This producl consisls ol a receiver module and two key lob ELECTRO lransmillers. A press of lhe bullon of lhe transmilter causes one ELECTRO ol lhe lwo oulpul wires on lhe receiver lo go momentarily 'high' ELECTRO wilh respect lo -12V. II can be used lo lurn car alarms on and ELECTRO ELECTRO of, door locking elc. Supplied wilh wiring inslruclions. ELEC TR O Cat. LR-8820 ELECTRO ELECTRO ELECTRO ELECTRO ELECTRO ELECTRO ELECTRO ELECTRON ICS JAYCAR ELEC TR ONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRON ICS ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELE CTRON ICS JAYCAR ELECTRONICS ELECTRONICS JAYCAR ELEC TRONICS JAYCAR ELE CTRONICS JAYCAR ELECTRONICS ELECTRONICS JAYCAR ELEC TR ONICS JAYCAR ELEC TR ONICS JAYCA R ELECTRONICS ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELEC TRONICS JAYCAR ELE CTRONICS SAVE $10 $99.50 Cat.AS-3022 $ 5 .95 TYPE4 $ 129.50 Small round speaker wllh an hi C:::==============::::::;sttl Impedance of soon. Could possibly be used as asmall addDIL REED RELAYS on tweeler for radio or TV elc. 40mm diameler. Mounting holes olt Cal. SY-4030 $4.25 · are 47mm apart. Depth 13mm. Cal. AS-3024 $ 1 .95 ,- :· : } JAYCAR JAYCAR JAYCA R JAYCAR JAYCAR JAYCAR ELECTR ONICS ELECTRON ICS ELECTRONICS ELECTRONICS ELE CTRONICS ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELEC TRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELEC TR ONICS JAYCAR ELECTRONICS IJAYCAR JAYCAR ELECTRONICS ,JAYCAR JAYCAR ELECTRONICSiJAYCAR JAYCAR ELECTRONICS JAYCAR JAYCAR ELECTRONICS IJAYCAR JAYCAR .ELEC.IRQNICS JAYCAR ELECTRON ICS ELECTRON ICS ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONIC$ JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR IAYC:AR ELECTRON! ELECTRON ! ELECTRON! ELECTRON ! ELECTRON! ELECIBO.NJ IC:i ICS ICS ICS ICS IC~ JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR 1/\Vl"'IID ELECTRONIC:i ELECTRONICS ELECTRON/CS ELECTRONICS ELECTRONICS r: , Cl"'Tnr"\htll"'C" JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS lf\V0f\O Cl Cf"' T Of"'l"llr"C JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR ELECTRONICS ELECTRONICS ELE CTRONICS ELECTRONICS ELECTRONICS 1r,.vr"f\C C: Cr" T Of"\"lll""C' JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS 11\Vr"/\D C l cr--rn,...., ........ ,... JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR ELECTRONICS ELE CTRONICS ELECTRONICS ELECTRONICS ELECTRONICS , •• , ..... ~,.. ... , ,.. ..... T .... ,...., .... ,....C' Bui Id a JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS 11\Vr"'/\0 C l er ' JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR ' ELECTRONICS ELECTRONICS ELE CTRONICS ELE CTRONICS ELECTRONICS 1 C("' T C("'\,.,llr"C JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR , f\ vr II o ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS c1 KA-1715 Car Brake Lamp Monitor $24.95 KA-1717 Subwoofer Adaptor $29.95 KA-1718 Auto NiCad charger $42.50 KA-1719 NiCad discharger $27.95 KA-1720 RGB to PAI encoder $39.95 KE-4730 Solar generator $13.95 KC-5056 Motorcycle intercom $69.95 KC-5059 Radfax decoder $44.95 KC-5060 Bal in/out for EQ $27.95 KC-5061 Bal ad on stereo EQ $17.95 KC-5062 Hot canaries $24.95 KC-5064 12 CH Mixer kit $999.00 KC-5065 16 CH Mixer kit $1399.00 KC-5071 Gel bait charger $69.00 KC-5072 Digital voice recorder $99.50 KC-5074 vox with delay $59.95 KC-5075 CAP meter 1pF - 9999uF $109.00 KC-5076 Reluctor high energy $46.95 KC-5077 Stereo PRE AMP $32.95 KC-5078 PSU Load Protector $17.95 KC-5079 Sine/Square Wave Gen $149.50 KC-5080 Horace the cricket $16.95 KC-5082 DC Offset for DMM $39.95 KC-5083 3 Digit counter $23.95 KC-5084 VCR Remote control ext $29.95 KC-5085 Discolight dimmer $39.95 KC-5086 DC - DC car converter $149.50 KC-5087 Big Escape Game $34.95 KC-5088 Fruit machine $26.95 KC-5089 Two Tone Siren $9.95 KC-5090 Sinewave Oscillator $16.95 KC-5091 20W Fluoro Inverter $32.95 KC-5092 12V Light chaser $21.95 KC-5093 Steam Sound Simulator $24.95 KC-5094 Stereo Audio Expander $39.95 KC-5095 DTMF Decoder $79.95 KC-5010 Capacitance meter $27.95 KC-5012 Car radio power supply $28.95 KC-5013 16Mhz Digital Freq meter $299.00 KC-5019 100Wamp module $38.95 Kit KC-5021 Protector car alarm $79.50 KC-5028 Train controller $89.00 KC-5030 High Energy Ignition $55.00 KC-5031 Optical tacho $49.95 KC-5032 Disco Light $159.50 KC-5033 Studio 200 Preamp $229.00 KC-5038 Universal power supply $12.95 KC-5039 Vader Voice $19.95 KC-5040 Speaker phone $89.00 KC-5041 Mini Milter $34.95 KC-5042 Knightrider LEDs $17.95 KC-5043 12W PA/Guitar amp $72.50 KC-5050 1/3 Graphic Equaliser $239.00 KC-5051 CD Compressor $49.50 KC-5052 Touch Lamp Dimmer $34.95 KC-5053 Extension Touch Dimmer $14.95 KC-5054 Garbage Reminder $24.95 KC-5055 Stereo 1/2 Octave. Eq. $349.00 KE-4014 Mixer preamp $44.95 KE-4023 Signal Speaker protector $22.50 KE-4029 NiCad battery charger $14.95 KE-4033 Temperature probe $32.95 KE-4050 ETl480 50W amp module $27.50 KE-4052 ETl480100W amp mod $34.50 KE-4048 ETI power supply $29.50 KE-4666 RS232 Centronics inter/! $32.50 KE-4690 ETl342 CDI $79.50 KE-4698 4 sector house alarm $29.95 KE-4711 Mini FM transmitter $9.95 KE-4724 Parametric equaliser $23.50 KE-4729 Guitar preamp $45.00 KJ-6504 8 channel mixer $595.00 KJ-6505 Console P supply above. $119.00 KJ-7000 Red light flasher $19.95 KM-3044 6000 Mosfet Module $139.95 KM-3050 Workhorse amp $35.00 KM-3065 RS true 232 interface $27.95 KM-3068 FM minder bug $11 .95 4-CHANNEL LIGHTING DESK KIT Refer Silicon Chip June 1991 This 4-chan nel lighling desk is inlended for lhealre, disco and music group applicalions. II has heavy duly circuilry and is able lo copewilh spollighls raled up lo 1000 walls or more. Operaling fealures • Four channels • 60mm slider pals • Click aclion flash swilcheswilh inlegral LEDs • Separale dimming for eachchannel • Masler dimmer conlrol • Flashon each channel • Master dimmer for fl ash • 4-channel chaser• Adjuslable chaser rale • Singleslep for chaser • Chaser on and off • Flash swilch LEDs mimic lamp display TheJaycar kit includes prepunched and silk screen case, original Cand Kswitches, original slider pols (Jaycar supplied lhesamples lo Silicon Chip) and all specified componenls. Beware of kils wilh non original parls. 1 $329 CS CS CS CS CS CS JAYCAR JAYCAR JAYCAR JAYCAR J AYCAR IAYCAR EU:CTRON ICS ELECTRONICS ELECTRON ICS ELECTRONICS ELECTRONICS El ECTRQNICS - JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR ELECTRONICS ELECTRONICS ELECTR ONICS ELECTRONICS ELECTRONICS ELECTRONICS . _ JAYCAR ELECTR ONICS J AY CAR ELECTRONICS J AY CAR ELECTR ONICS J AYCAR ELECTR ONICS JAYC AR ELECTRONICS IAYCAR.£1.EC.Ifil)NICS JAYCAR JAYCAR JAYCAR J AYCAR JAYCAR I AYCAB ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTR ONICS JAYCAR El ECIRONICS_JAY_CAB _ . _ ELEC TRONICS J AYCAR ELEC TRONICS J AYC AR ELECTRONICS J AYCAR ELE CTRONICS J AYC AR ELECTRONICS J AYCAR ELECTRON ICS .J AYC AR ELECTRONICS ELEC TRONICS ELECTRONICS ELECTRONICS ELECTR ONICS FLECTRONICS -· J AYCAR J AYCA R JAYCAR JAYCAR JAYCAR J AYCAR cr,TonN ICS J AYCAR NICS JAYCAR NICS JAYCAR NICS JAYCAR NICS JAYCAR NICS JAYCAR NICS JAYC AR NICS J AYCAR NICS JAYCAR NICS JAYCAR NICS JAYCA R NICS JAYCAR NICS JAYCAR NICS J AY CAR NICS J AYCAR NICS JAYCAR NICS JAYCAR NICS JAYCAR NICS JAYCAR ,. NICS JAYCAR NICS JAYCAR NICS JAYCAR NICS JAYCAR NICS JAYCAR NICS JAYCAR NICS JAYCAR NICS JAYCAR NICS JAYCAR NICS JAYCAR , NICS JAYCAR NICS JAYCAR NICS JAYCAR NICS JAYCAR NICS JAYCAR NICS JAYCAR NICS JAYCAR NICS JAYCAR NICS JAYCAR . NICS JAYCAR NICS JAYCAR NICS JAYCAR NICS JAYCAR NICS J AYCA R NICS JAYCAR NICS JAYCAR NICS JAYCAR NICS JAYCA R NICS JAYCAR NICS JAYCAR NICS JAYCAR NICS JAYCAR NICS JAYCAR NICS JAYCAR NICS JAYCAR NICS JAYCAR NICS JAYCAR NICS JAYCAR NICS JAYCAR NICS JAYCAR NICS JAYCAR NICS JAYCAR NICS JAYCAR NICS .IAYCAR NICS JAYCAR NICS JAYCAR NICS JAYCAR NICS JAYCAR NICS JAYCAR NICS JAYCAR NICS JAYCAR NICS JAYCAR NICS JAYCAR NICS JAYCAR NICS JAYCAR NICS JAYCAR NICS JAYCAR NICS JAYCAR NICS JAYCAR NICS J AYCAR NICS J AYCA R NICS JAYCA R NICS JAYCAR NICS JAYCAR NICS JAYCAR ICS JAYCAR ICS JAYCAR ICS JAYCAR ICS JAYCAR ICS JAYCAR ICS JAYCAR ICS JAYCAR ICS JAYCAR ICS JAYCAR ICS JAYCAR ICS JAYCAR ICS JAYCAR ICS JAYCAR ICS JAYCAR ICS JAYCAR ICS J AYCAR ICS JAYCAR : ICS JAYCAR 1 ICS JAYCAR I ICS JAYCAR I ICS JAYCAR I ICS JAYCA R I __ _ _ __ ICS JAYCAR I ELECTRONICS JAYCAR ELECTR ON ICSJAYCAR 1 ELECTRON ICS JAYCAR ELECTRON ICS J AYCAR I ELECTRON ICS JAYCAR ELECTRON ICS.JAYCAR I ELECTRON ICS JAYCAR ELECTRONICS JAYCAR I ELECTR ONICS J AYCA R ~LECTRONICS JAYCAR I ELECTR ONICS JAYCAILELE CTRONICS .J AYCAR 1 Don't just sit there on these cold nights watching TV. Do something constructive and build a kit. For full details on all these kits see our catalogue. KA-1724 Vo lt up 1.5V to 9V $19.95 KA-1725 Pro series 1 power amp $599.00 KA-1726 Pro module less mosfets $47.95 KA-1728 VHF powermatch $49.95 KA-1729 RF probe - suit above $7.50 KA-1730 Pro series 2 pre-amp $329.00 KA-1731 Transistor/Fe! tester $32.00 KA-1732 Flexi timer $16.95 KA-1733 CRO adaptor $24.95 KA-1734 Quad DI box $79.95 KA-1735 CRO Adaptor for Monitors $179.50 KA-1109 Electronic Fence $23.50 KA-1115 300Wamp module $119.95 KA-1116 300Wpowersupply $115.00 KA-1117 300W speaker protector $23.50 KA-1119 Transistor tester $21.50 KA-1230 Zener diode tester $16.95 KA-1390 Freq counter 50MHz $169.50 KA-1392 Prescaler 500MHz $46.50 KA-1430 Vocal canceller $24.95 KA-1550 Deluxe car alarm $89.50 KA-1556 Ultra sonic move detector $34.95 KA-1574 30V/1A power supply $99.50 KA-1598 40W inverter 12/230V $99.95 KA-1610 300W inverter 12/230V $269.00 KA-1630 12Vlampflasher $12.95 KA-1652 Blueprint 60/60 $369.00 KA-1660 Electric fence $59.50 KA-1675 Screecher car alarm $37.50 KA-1682 Dual track power supply $139.95 KA-1683 Battery monitor $14.95 KA-1690 DI box $39.95 KA-1692 Voice operated relay $24.95 KA-1693 Metronome $19.95 KA-1696 Econ. Temp probe DMM $19.95 KA-1699 Bench amp-signal trace $39.95 KA-1702 50MHz Dig Freq meter $79.00 KA-1706 Cheap capacitance meter $19.95 KA-1707 Powermate 2 $119.00 KA-1710 Beepo Continuity Tester $19.95 JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR ;AH t:. L t:L.; I H U N ll..i::i JA Yl,,.;AH t:. L t:.L,; IH UNI L.; ;:, JAYL.;AH t:LC.l,; I H UN tl,;;:, JAYl..,;AH t:L t:l,; I H UN IL,;;:, JAYl..,.;AH t:L t:l..i I HUN Jl.i;:, J AY \,.; AH t::Lt: Li I H UN II..,;:, J A Yl.., AH t:L t:\., I HUN II...,;:, JAY l..i A H t:.Lt: I..., I HUN II...,;:, .Jl"ITV/'\n t: L C I.., I H >.1 :AR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS :AR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS :AR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS J AYCAR ELECTRONICS JAYCAR ELECTRONICS :AR ELECTRONICS JAYCAR ELEC TRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS :AR ELEC TR AR ELEC TR AR ELEC TR AR ELECTR AR ELEC TR "\((/ . •.. ,: . . ·.;.. ,, . .: ' ···•: ,::: ,•,•,•::• AR ELECTR AR ELECTR AR ELECTR AR ELECTR PC mount- pins are 15mm apart. Also includes mounting holes AR ELECTR Al lasl a low cos! qualily, portable bulane powered flame lorch. for panel mounling. Operates anywhere from 6 to 12 volts DC. Size AR ELECTR Ideal for lhehobb~sl and professional. Adjuslable flame, 28mm diameter, 35mm mounting AR ELEC TR ccmplelely porlable, up lo 90 minules use per fill, adjuslable holes, 14mm high excluding pins AR ELECTR lemperature ccntrot, mini size, uses standard butane gas AR ELEC TR Cat. AB-34fi0 tighter fuel. Ideal for shrinking heatshrink lubing. AR ELECTR AR ELECTR Cat. TS-1410 AR ELECTR AR ELECTR AR ELECTR AR ~LECTR AR ELECTR AR ELECTR Cat. TS-1412 AR ELECTR AR ELECTR AR ELECTR AR ELECTR AR ELEC TR AR ELECTR AR ELECTR AR ELECTR AR ELECTR AR ELECTR AR ELEC TR AR ELECTR With this in yo AR ELECTR car you will have AR ELECTR Hycasol is supplied in a bollte inslead AR ELECTR added protection AR ELECTR of the usual environmentally unsound againsl illegal en AR ELECTR spray can. II conlains 500ml which is 2 from movement AR ELECTR 1(2 times lhe amounl of lhe spray can. well as broken AR ELECTR To use simply pour conlenls inlo a AR ELECTR windows. Limited glass or metal ccnlainer, brush on AR ELECTR quantity. AR ELECTR circuil board and return to bollte afler Cal LA-8960 \R ELECTR use. Can be re-used many limes. PCB's AR ELECTR should be cleaned. Hycasol will \R ELECTR dissolve flux residues and grime leaving \R ELECTR the track work and board absolulety \R ELECTR \R ELECTR clean. Cal. \R ELECTR JAYCAR JAYCAR JAYCAR JAYCAR ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS JAYCAR JAYCAR JAYCAR JAYCAR ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS JAYCAR JAYCAR JAYCAR JAYCAR ELECTRO ELECTRd ELECTRO ELECTRC IHC JAYCAR • No 1 for HOBBYISTS ••, . •.. BUTANE MINI TOOL 6-12V DC BUZZER BARGAIN ONLY $1 2.95 CRAZY PRICE 1-9 $2.95 10-99 $2.00 100 up $1.50 SOLDERING OPT ION $9.95 Top quality buzzer. Operates from 3-16V DC. Typical frequency 3700Hz. Current draw SmA. Sound pressure level 91dB. Size 17mm(H), 23mm dia, mounling hole dia 28mm. UDPC p qualily 96dB PC mount zzer. Model Al-550KA. Limited . Pin spacing 15mm, Supply Its 3-1 SV DC, currenl draw A, frequency 2800Hz. Size mm (H), dia 23mm. I. AB-3458 .95 REUSABLE PCB CLEANING SOLVENT SPADE LUG MADNESS Stock up now. This bargain won't lasl tong. Slandard QC , 6.3mmspade lugs. ~ . 50 MALE, 50 FEMALE, 50 PLASTIC COVERS Cal. PT-4510 NLY $39.95 NA-1050$16.9 5 \R ELECTRCJ;/:::::==============:::::::"./fl \ R ELECTR \R ELECTR \R ELECTR \R ELECTR \R ELECTR \R ELECTR \R ELEC TR \R ELECTR \R ELECTR \R ELECTR 1R ELECTR ,R ELECTR ,R ELECTR ,R ELECTR ,R ELEC TR ,R ELECTR ,R ELECTR ,R ELECTR ,R ELECTR .R ELEC TR O .R ELECTR .R ELECTRO R ELECTR R ELECTRO R ELECTRO R ELEC TRO R ELECTRO R ELECTRO R ELEC TRO R ELEC TR O R ELECTRO R ELECTRO R ELECTRO R ELECTRO HOBBY BOX Oualily ABS black plastic box. Ideal for use in cars as can be supplied with underdash mounting bracket II may look familiar to many people as its a radar detector enclosure. The Iron! panel has a square hole and lhe rear panel has some odd shaped holes, bul cables can be run through and in acar they won'! be seen anyway. Dimensions 39(H) x 125(W) x 127(D)mm. Available two ways: Box A includes top, bottom, front and rear panel, mounling brackel and two lhumb screws. Cal HB-5942 ■ Box B includes top, bollom, front and rear panels only. $ Cal HB-5940 . $8.95 '. ... ' . .·.• .. ::::::/( TOP QUALITY CAR ALARM TAMPER (PINl SWITCHES Spring loaded swilch for mouniing in car doers, boo! elc for alarms. Top quality stainless steel. Will lasl alifelime. Two sizes. Short - overall length 38mm, pin travel 6mm. Cal LE-8780 $3.95 Long - overall length 53m pin !ravel 12mm. Cal LE-8785 $3.95 5 95 $ 2.95 D LE a 1.4mt length of twin fig 8 polarised ea lder and a2A 3AGfuse. Ideal for running ipment from the car, with the added bon useholder on a300mm single wire wilho .10. So slock up now! -201 4 GARE WER r running a 12 ·❖❖❖•.~===============:.:i~~7;:~==="'-" ❖ PROFESSIONAL RACK ENCLOSURES NOW AVAILABLE •"' '"► • 't'• See calalogue for full delails · ' .,.. 1 UNIT $89 Cat. HB-5120 2 UNIT $109 Cat. HB-5125 3 UNIT $11 9 Cat.rtB-5130 4 UNIT $ 13 9 Cat. HB-5135 5 UNIT $ 14 9 Cat. HB-5140 ELECTRd ''."'ii .., R ELECTR : ~t~g;:g R ELECTRO R ELECTRO RE LEC TRO R ELECTRO R ELECTRO cnLECTRo '1 ELECTRO "ELECTRO , ELECTRO ~~t~g:g ~~t~g;:g , ELECTRO HLECTRo , ELEC TR O , ELEC TRO <ELECTRONICS 'ELECTRONICS i ELECTRONICS , ELECTRONICS 1 ELEC TRONICS ~ ELEC TRONI CS 3 ■- • JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR j AYCAA ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS ELEC TR ONICS ELECTRON ICS JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS ELEC TR ONICS ELEC TRON ICS JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR IAYGAB ELECTRONICS ELECTRONICS ELECTRONICS ELF.CTRONICS ELECTRON ICS JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR fl ECIRON l(;S .IAYC..A.R DNESS Prices Include tax. Cat. PP-2000 LY $1.20 ea LY 1-9 6O~ =====~ 10-99 45~ 100 up 3O~ ELECTRONICS. ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS J.AYCAR FI ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS FCTAO/\JICq_ l A._Y..C.11.RJ;L~C.TAf""l!\1J ~ JAYCAR JAYCAR JAYCAR JAYCAR J AYCAR ELECTRONICS IJ AYCAR ELECTRONICS ,JAYCAR ELECTRONICSiJ AYCAR ELECTRONICS JAYCAR ELECTRONl~~l~~YCAR 1ll.vr1, 0 c.,a C:CTDOP\11 vr-11 0 ELECTRONICS ELECTRONICS ELEC TRONICS ELECTRONICS ELECTR ONICS t:: 1 c: r T.c:uJhllf''C JAYCAR JAYCAR JAYCAR JAYCAR J AYCAR ELECTRO~ ELECTRO[', ELECTRO~ ELECTRO!'< ELECTRON ff\VCII D c:1 r crno• ll.,.;) JA YL, AH t::Lt;I,.., I H U NI Li:::> JAn..,AH . t::Lt::V I HUN IL,:::, JAYL,AH t:Lt:L, I H UN IL,:::, JAYl.,.,AH t:Lt:L., I HUl'lll..,-:> JAYL,AH t:: Lt:.l., I HUN J\,.,;:, JAYL,AH t:. L t:L, I HUN IL,;:, JA Y L.,AH t:.Lt:L, I HUN tL,:::, JAYl.,AH t::Lt:L, I HUN IV:::, JAYL,AH ICS ICS ICS :1cs !ICS JAYCAR JAYCAR JAYCAR JAYCAR ELEC TR ONICS ELECTRO NICS ELEC TRON ICS ELECTR ON ICS · c:: JAYCAR JAYCAR JAYCAR JAYCAR IAV ELEC TRON ICS ELECTRON ICS ELE CTRON ICS ELECTRON ICS AA i:= 1 i=rTA 1\ 1 re:: JAYCAR JAYCAR JAYCAR JAYCAR ELECTRON ICS ELECTRONICS ELECTR ONICS ELECTRONICS Av i= c "' 1r JAYCAR JAYCAR JAYCAR JAYCAR ELE CTRONICS ELECTRONICS ELECTRONICS ELECTRONICS " A 11rc: JAYCAR JAYCAR JAYCAR JAYCAR ELECTRONICS ELECTRONICS ELECTRONICS ELE CTR ONICS 11'Vf"'l'IA 1= 1 T re: JAYCAR JAYCAR JAYCAR JAYCAR vrr,, 1 ELECTRONICS ELECTRON ICS ELECTRONICS ELECTRONICS 1=1 c TAf"'ll\1 1rc:: JAYCAR JAYCAR JAYCAR JAYCAR ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS JAYCAR JAYCAR JAYCAR JAYCAR 1tivrtiA 1=1 i=rn:Jnl\11rc:: 1avr6A JAYCAR • No 1 for NEW PRODUCTS : EDUCATIONAL SOLAR ENERGY KIT Available once again Pack contains 100 pieces. May lndude transistors, diodes, IC's, computer chips, RAM, TTL, CMOS, etc. We cannot guarantee that all Items above will be induded but we can guarantee al least 100 brand new prime specsemis and $10 will represent an absolute bargain. Cal. ZP-8990 $ 24.95 • make an electrical circuit • learn how lo increase voltage • learn how lo increase current • learn how lo make a solar panel • use solar power to produce energy for a radio, calculator, ballery charger and 1.5V casselle player. )} The kit includes 8 solar cells, Which fit Into a :\{ plastic housing and can be connected up In {% either series and parallel, a motor and )l mounting bracket, afan, tool for connecting i? solar cells and a 10 page booklet explaining the why's and how's of <'L. . . ,................. solar energy. · ......... .. • ~ ,;-,..,........,..,......,..,....._____ _______ _ 1111111111 BEGINNERS GUIDE TO THE IBM PC p;,, ,>:r► 1_--0 __W ...._E_R ____P .........R......... IC .......E_S _ O _ N_ H __I_G...H ........, BRIGHTNESS LED's JAYCAA JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR CS cs CS cs JAYCAR JAYCAR JAYCAR JAYCAR g~ 3:~g:: cs JAYCAR CS JAYCAR CS JAYCAR CS JAYCAR CSJAYCAR CS JAYCAR CS JAYCAR CS JAYCAR CS JAYCAR . CS JAYCAR CS JAYCAR ~ i?•:•:·• CSJAYCAR CS JAYCAR ICS JAYCAR CS JAYCAR CS JAYCAR CS JAYCAR ICS JAYCAR ,,>l g! j;~g;~ 1 cs JAYCAR CS JAYCAR CS JAYCAR ICS JAYCAR cat.ZD-1792 ea ICS JAYCAR 1000mCd RED WATER CLEAR ICS JAYCAR ICS JAYCAR cat.ZD-1793 ea CS JAYCAR CS JAYCAR 3000mCd RED WATER CLEAR CS JAYCAR cat. ZD-1796 CS JAYCAR CS JAYCAR 1&DmCd YELLOW WATER CLEAR Description Price ICS JAYCAR cat. zo-1795 ICS JAYCAR MC145436 DTMF Decoder$9.95 CS JAYCAR 4514 4-16 Decoder $3.95 80mCd GREEN WATER CLEAR CS JAYCAR , 4043 Quad RS latch $2.20 CS JAYCAR I cat. zo-1794 ea DAC 0800 $4.75 CS JAYCAR , 74LS323 Shilt register $8.95 CS JAYCAR I ...,..,,,..,,,,.,,,,,,,, . CSJAYCAR I ICS JAYCAR I ICS JAYCAR I ICS JAYCAR I We are sick and tired of paying too much for reed relays through local suppliers, so we have done ICS JAYCAR I something about ii. These new ones are directly imported by Jaycar. Check out the low prices. These CS JAYCAR I CS JAYCAR I are NOT OIL mount. ICS ,IAYCAR I ICS JAYCAR I ICS JA YCAR I WAS $5.25 WAS $5.95 ICS JAYCAR I Yes, the Metex M3650CR will interface with your computer via RS-232. Connecting ICS JAYCAR I lead and software disk supplied. Monitor store and print out the ICS JAYCAR I Cal. SY-4036 Cal. SY-4038 ICS JAYCAR I output of the DMM on computer. It will take readings over time and find and hold ICS JAYCAR I mimimum and maximum readings. CS JAYCAR I CS JAYCAR I CS JAYCAR I Function Range Resolution CS JAYCAR I DC Vollage 200mV 100µV CS JAYCAR I 2V 1mV CS JAYCAR I CS JAYCAR E 2r:N 10mV CS JAYCAR E 200/ 100mV CS JAYCAR E 1000V 1V CS JA YCAR E AC Voltage 200mV 100µV CS JAYCAR E 'lv 1mV CS JAYCAR E 2r:N 10mV CS JAYCAR E CS JAYCAR E 100mV 200V CS JAYCAR E 75(J,J 1V CS JAYCAR E DC Current 2mA 11,t\ CS JAYCAR E 200mA 1001M' CS JAYCAR E 20A. 10mA CS JAYCAR E CS JAYCAR E AC Current 2mA 11,t\ CS JAYCAR E 200mA 1001M' CS JAYCAR E 20A 10mA CS JAYCAR E Resistance 2000 0.10 CS JAYCAR E 2kQ 10 CS JAYCAR E CS JAYCAR E 20kQ 100 CS JAYCAR E 100,Q 200k0 CS JAYCAR E 2MQ 1kQ S J AYCAR E 10kQ 20MO S JAYCAR E Capacitance 2000pF 1pF S JAYCAR E S JAYCAR E 200nF 100pF S JAYCAR E Cal. OM-1450 S JAYCAR E Frequency 20kHz 10Hz S JAYCAR E 200kHz 100Hz S' JAYCAR E ,S JAYCAR E JAYCAR ELE TRONICS JAYCAR ELECTRONICS J AYCAR ELECTRONICS J AYCAR ELECTR ONICS JAYCA R ELECTRONICS JAYCAR EC YCAR ELECTRONICS JAYCAR E JAYCAR ELECTRONICS JAYCAR ELECTRONI CS JAYCAR ELECTRONIC S JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR E JAYCAR ELECTRONICS JAYCAR ELECTRONICS J AYC AR ELECTRONICS J AYCAR ELEC TRONICS JAYCAR ELECTRONICS JAYCAR ELECTRON ICS JAYCAR ELEC TR ONICS JAYCAR ELECTRONICSJAYCAR E JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCA R ELECTRONICS JAYCAR ELE CTRONICS JAYCAR ELEC TR ONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS J AYCAR ELECTRONICS JAYCAR E JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCA R ELECTRONICS J AYCAR ELECTRONICS JAYCAR ELEC TRONICS JAYCAR ELECTRONICS JAYCAR ELE CTRONICS JAYCAR 1::LECTRON ICS JAYCAR E J AYCAR ELECTRONICS JAYCAR ELECTRONICS JAYC AR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICSJAYCARJ:; Cat. ZZ-8465 all 5mm round styles - 500mCd RED WATER CLEAR NORMALLY $9.50 NOW ONLY $1 JUNE BARGAIN $3.95 NOW ONLY $2 NOW ONLY $3.25 ea NOW ONLY SO~ ea NOW ONLY SO~ $9.95 REED RELAY PRICES SLASHED METEX DIGITAL MULTIMETER WITH COMPUTER INTERFACE PLUS: • Bargraph • Frequency • Transistor • Logic • Relative offset • 3.5 digit • 20 Amp current • Carry case • Overload indicator • Data hold • Mimimum/maximum hol • Diode a nd c ontinuity • Range selector beepe r 5 VOLT SPST 12 VOLT SPST NOW $2.75 NOW $2.95 SPECIFICATIONS 2W ,CS CS ICS ,CS CS CS l l l!!!!M===::=:===~·= : :::= = - $1 0 JAYCAR JAYCAR JAYCAR JAYCAR g~ 3:~g:: SEMICONDUCTOR PACK Ideal for students or anylxldy who wanls lo learn about solar energy. This kit shows you how lo make a solar system. Cat. KJ-6692 • make a solar circuit By Bruce Collins This book assumes that you have very lillle or no knowledge of using a computer. II will lake your hand and guide you through the compuler maze. By the last chapler, you will certainly know your way around your new IBM compalible or genuine computer. The book covers such topics as:- what Is a computer?, formal and copy commands, disk drives, DOS commands, software generally, computer add ons, mainlenance and a lot more. . An Ideal book for a computer novice. Soflcover, 69 pages, 21 O x 140mm. Cal.BC-1120 ELECTRONICS ELECTRONICS ELEC TR ONICS ELECTRONICS 1=1 i=r.TAnMICS CS CS CS CS CS CS 11¥ ~ =lll/!IJll!-- The electronics magazine for the enthusiast Four good reasons why you should subscribe to SILICON CHIP You get a 12.5% discount on the newsstand cover price. Recently, we had to increase the cover price of the magazine because of rising costs but we have held the subscription to the old price so you get the benefit. You'll never miss an issue. Sometimes it can be very hard to find SILICON CHIP in the newsagents because it sells out early or gets buried under other magazines. By taking out a subscription you don't have to search for it - it arrives in your letter box in mint condition. We wrap it in tough plastic to make sure of that. JUNK MAIL Most magazines sell their subGet a discount on the binder too. You'll want to store scriber lists to mail order comand protect your issues of SILICON CHIP so when you take out panies, to earn extra income . . a subscription you get a further discount on the binder. By Be assured that we will not do taking out a 2-year subscription and buying two binders at this. Your privacy will be respectthe same time, you get even bigger savings. And we ed and you will not be deluged despatch the binder(s) with your first issue so you have it with unwanted mail. . right from the start. SPECIAL NEWSLETTER From time to time, we will have special promotions Subscribers will receive a specand offers in the magazine, -like the Bose Lifestyle competitial newsletter at least twice yearly which will contain inforion featured in the September to December 1990 issues. mation on upcoming SILICON When you are a subscriber you are automatically eligible for CHIP projects and sper.ial offers, these and you get the chance to benefit. available only to subs~ribers. Interested in these savings and benefits? Just fill in the coupon on the following page and send it with your remittance. You'll be glad you did. Why not do it today? Specially designed binders for SILICON CHIP are always available. Made with a distinctive high quality 2-tone vinyl, you can obtain them at a discount when you take out or renew your subscription. The price details are on the coupon overleaf. I hope to see you as a supporter soon. Leo Simpson, Publisher Just fill in the coupon on the following page MAGAZINE BINDERS ~ JULY 1991 57 ~~~ORDER FORM . I 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 add A$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_ _ _ SLOPPY JOE: Please send me _ _ Sloppy Joe(s) $A27.95 including postage. (Overseas orders please add A$3.00 for <at> 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 $A l.00 per issue for postage. ISSUE YEAR ISSUE YEAR ISSUE YEAR ISSUE YE AR TOTAL $A SUBSCRIPTIONS .. RATES: □ NEW SUBSCRIPTION: Month to Start □ RENE WAL: Sub No. (PLEASE TICK ONE) Start In Australia □ GIIT SUBSCRIPTION: Month To Start Your Details Mr/Mrs/M s: Address: Postcode 2 years (24 issues) 1 year (12 issues) O$A84 O$A42 Australia with Binder(s) O$A105 O$A53 NZ & PNG (Airmail) O$A130 O$A65 Overseas Surface Mail O$A130 O$A62 Overseas Airmail O$A240 O$A120 Daytime telephone number: _ _ __ _ _ __ Encl osed is my cheque/money order for $ _ __ myDIEBI D !( ll-) D l I 1111 11 1 11111111~11~ ~ or debit Gift Subscription Details Message: _ _ _ __ _ _ _ _ __ _ _ __ v1sA Card expiry date Signature _ _ _ _ _ _ _ _ __ (02) 979 6503 Fax the coupon with your Credit Card details 24 Hours, 7 Days a Week _ _ !__ Mr/Mrs/Ms: _ _ __ __ _ _ _ _ _ _ __ Address: _ _ _ __ _ _ _ _ _ _ _ _ __ _ _ __ _ __ _ _ _ _.Postcode_ _ __ u . . (02) 979 5644 9am - 5pm Mon-Fri. Please have your Credit Card details ready. Mail coupon to: FREEPOST 25 Silicon Chip Publications PO Box 139 Collaroy Beach NSW 2097 No stamp required in Australia I PRODUCT SHOWCASE I New range of solder suckers/tweezers Scope Laboratories has a range of four solder suckers available. Three have plastic bodies and one has an anodised metal body. All are available with static dissipation nozzles as an option. Also available are 130mm ceramic tipped tweezers which can be handy when soldering parts in difficult positions. The ceramic is zirconium ox- Deluxe lightboxes for PC and label production Need a lightbox for photographic exposure of PC board or Dynamark label materials? Kalextronics has just released three new lightboxes which are well finished in white enamelled steel. The prototype model pictured in ide, chosen for its abrasion resistance, rigidity and chemical inertness. The handle is made from springy glass fibre reinforced polypropylene. For further information, contact Barry McIntosh at Scope Laboratories, PO Box 63, Niddrie, Vic 3042. Phone (03) 338 1566. the photo is the Portuvee 4 which can cope with artwork up to 28 x 13.5cm. It also has a printed guide which shows recommended exposure times . for the most popular Dynamark label materials. It is fitted with a recessed 3-pin mains socket so it can be connected via a standard extension lead. This lightbox would be suitable for most organisations, particularly Customised SLA battery packs If you require a special SLA battery pack for a particular application and the current models aren't suitable, then Siomar Battery Industries has the solution. The range starts with the rugged, sealed 2V cylindrical cells made by Gates Energy Products in the US. Siomar then assemble these into 4, 6, 8, 10 and 12V batteries here in Australia. For more information, contact Siomar Battery Industries, 15 Colray Ave, Osborne Park, WA 6017. Phone (09) 443 1000. schools and technical colleges. Also in the range is the UV2 lightbox which can handle artwork up to 40 x 27cm and -the Portuvee 6 which can handle artwork up to 43 x 40cm. Prices are $225 for the Portuvee 4, $650 for the UV2 and $625 for the Portuvee 6 (all prices exclude sales tax). For further information, contact Ken Laird at Kalextronics, 40 Wallis Avenue, East Ivanhow, Vic 3179. Phone (03) 497 3422. ] ULY 1991 59 Transient protection for faxes and modems If you care about protecting your computer, modem or fax machine from transient voltages there are two products you should consider. The Faxguard and Compuguard are designed and made in Australia by Critec Pty Ltd. The Faxguard is specifically designed to protect your fax machine from lightning and transient spikes on both the phone and power lines. You simply plug your fax into the Faxguard and then plug the Faxguard into the phone and power outlets. The.,unit effectively reacts to any incoming faults in a few microseconds, preventing them from reaching the sensitive circuit cards inside your fax. A unique safety feature of the design is a non-linear transient clamp device which connects the phone lines' protective return path to the mains earth under fault conditions but provides near total isolation under normal conditions. The Compuguard is designed to . protect computer systems with or without modems and is suitable Compactshortwave radio from Philips With events continually changing around the world, shortwave radio has increased its following as people tune in for instant world news. With this in mind, Philips has released a compact 9-band receiver featuring FM, LW and MW bands, and six shortwave bands. The AE3205 comes with both telescopic and ferrite rod antennas, a LED tuning indicator and an earphone socket, and can run from either mains for use with either two or 4-wire modems. Both the Compuguard and Faxguard are capable of withstanding a current surge in excess of 6000 amps without sustaining damage. Under test conditions, when injected with a 6.5kV 500 amp lO0kHz high energy pulse (317 Joules), over 99.9% of the transient energy is clamped and filtered , leaving a harmless residual voltage. Both units are available from the agent for Critec, Raytec Data Systems. They carry a complete range of transient protection equipment for all types of applications. For further information, contact Peter Welsh at Raytec Data Systems, PO Box 1174, Gosford, NSW 2250. Phone (043) 23 1966. wheel tuning and stereo sound, with facilities for plugging in a pair of stereo headphones for personal listening. The AE3205 is available for $499.95 and the AE3405 for $129.95. Contact Domenic Genua at Philips Consumer Products, 16 Blue St, North Sydney, NSW 2060. Phone (02) 742 8311 . or battery power. Philips also has the AE3405 dual-wave version which also has a 9-band range. It includes electronic AM/FM switching, thumb- IBM 3480 compatible cartridge tape drive Midget speaker and IEC mains socket Want a teensy, weensy ·little speaker for that compact electronic project you are working on? This unit is only 40mm across and 14mm deep and is available from Stewart Electronic Components Pty Ltd at the ridiculously low price of $1 or a mere 50 cents each in quantities of 200 or more. Also available from Stewart's is a fused IEC mains socket at the bargain price of $5 each. You'll find this and lots of other products at Stewart Electronic Components Pty Ltd, 44 Stafford Street, (PO Box 281) .Huntingdale, Vic 3166. Phone (03) 543 3733. 60 SILICON CHIP Elmeasco has released a new lowcost IBM 3480 compatible half-inch cartridge tape drive in Australia from Cipher Data Products Inc in the USA. The T480 TapeXpress uses standard 200 and 220 megabyte cartridges and when fitted with the optional cartridge loader, which accepts up to 10 cartridges, the T480 total on-line capacity can be extended to 2.2 gigabytes. It's also capable of emulating reel-to-reel tape drive interfaces. It's fitted with the industry standard SCSI interface and has a transfer rate of 1.5Mb per second, allowing 2.2Gb to be transferred in about 40 minutes compared to 2.5 hours for an 8mm helical scan device. For more information, contact Paul Twigg at Elmeasco Instruments Pty Ltd, PO Box 30, Concord, NSW 2137. Phone (02) 736 2888. New subwoofers from Jaycar The HF801 and HFlO0l subwoofers are new additions to the Jaycar range. The HF801 has a nominal 8-inch diameter and is rated at BOW RMS on program signals. Its voice coil impedance is 8Q at 400Hz and its free-air resonant frequency is 41Hz. The HF1001 is a 10-inch version rated at 120W RMS. Its voice coil High volume forms and label printer Trying to send multi-part forms and labels through a standard printer is not only time consuming but almost impossible with thick forms and adhesive labels. Elmeasco has available from Facit Inc a wide carriage, heavy-duty, model E7650 printer. It has a flat platen and straight through paper path to accommodate up to 9-part forms and adhesive labels. Cut sheet forms can be fed via the front or optional top entry paths. It automatically adjusts for form thickness and uses a built-in FormFinder system which senses and locates the top, right and left edges of the form. A Z-axis control changes the printhead gap to accommodate different form thicknesses. Capable of 600cps at 15cpi and 400cps at 10cpi, it also has a 16-inch per second paper slew rate, providing high throughputs. IBM Proprinter XL and Epson FX/JX (colour) emulations are standard, as are dual RS232C and Centronics parallel interfaces. Setup and control can be done through an easy to use control panel with LED display, allowing storage of up to 10 different configurations. For more information, contact Paul Twigg at Elmeasco Instruments Pty Ltd, PO Box 30, Concord, NSW 2137. Phone (02) 736 2888. impedance is also 8Q at 400Hz and its free-air resonant frequency is 39Hz. Both speakers feature large magnet assemblies and heavy paper cones with foam rubber roll surrounds. The HF801 retails at $99.50 and the HFlO0l for $129.50. They are available from any Jaycar Electronics store. RAYTEC DATA SYSTEMS Surges and spikes, induced by lightning or power line faults can destroy your fax or computer. The 'FAXGUARD' is the ultimate protective device for fax machines or computer/modem combinations. Utilising solid state clamping in addition to high energy arrestors it provides full powerline filtering with superior telephone line transient supression. LUMEN PC MIGHT-25 FAX GUARD ANTRIM TOROIDAL TRANSFORMERS $200.00 The affordable back-up powersupply Protection against brownout and blackout 250 VA, 240V 50Hz output. Fully self-contained, automatic operation Inbuilt mains filtering and o/load protection Designed specifically to back-up computer systems Typically 6 minutes backup Other models available in 350VA & 550VA *** * * * SUI~ER.SfECIALS ON INPUT D_EVICES INFRA-R ED MOUSE PEN CORDLESS MOUSE * Hold it in your hand KEYBOARD like a pen. *Technology. Uses latest Infra-Red *standard Emulates a *andAmazing accuracy keyboard needs less space. *systems M'soft / mouse Enables remote * M'soft compatible. *control compatible. of your PC Normally $149.00 Eo.c,M;t.aa/Jt. S99 00 Normally $199.00 Eo.c,M,K.aa/Jt. SH5 00 Normally $525.00 Eo.c .t!L& aa/Jt.S399 00 * We stock a full range of PC compatible components. *andWePeripheral carry Lightning Surge Arrestors, Back-up Power Supplies, Coaxial supressors and Line Conditioners for all applications. * We are Authorised Agents for CRITEC AUST. * Mail and phone orders welcome · (:Ne accept Bankcard and Visa Card). * Call today for a free copy of our latest catalogue. PHONE 043-231966 FAX 043-233760 PO BOX 1174 GOSFORD STH N.S.W. 2250 * I SY A to 625V A available ex-stock * 1 SVA to 2KV A _available to order * Largest ex-stock source of toroids in Australia * Competitive pricing available for OEMs and resellers HARBUCH ELECTRONICS PTY LTD 90 George St. HORNSBY NSW 2077 Phone (02)476-5854 Fax (02)476-3231 JULY 1991 61 Loudspeaker protector for stereo amplifiers This simple circuit will protect your expensive loudspeakers from overdrive or from amplifier failure. It can be fitted to just abol}t any amplifier & will also eliminate switching thumps. By BOB FLYNN Although som e audio amplifiers includ e loudspeaker protection circuitry as standard, there are many amplifiers that do not. In particular, this important feature is often left out of high-power amplifiers , either to reduce cost or to eliminate switching in the audio path. And that can be bad news for your loudspeakers. Almost all audio amplifi ers use direct-coupled output stages - ie, there is no output coupling capacitor. This means that if an output transistor goes short circuit, virtually the full supply rail to that part of the circuit will be applied to the loudspeaker. The result is usually a blown loud- speaker voice coil or damaged suspension, probably before the unfortunate user even realises that anything is amiss. For example , consider a 100W amplifier with ±50V supply rails driving a loudspeaker with a voice coil DC resistance of 6.5il If one of the supply rails is shorted to the speaker, the resulting power dissipation in the voice coil will be 50 x 50/ 6.5 = 385W (or at least it will be until the power supply fuses blow. Obviously, there are not too many voice coils that will withstand that sort of treatm ent for long. In fact, the voice coil of a typical 50W or 100W loudspeaker would burn out almost instantly. Depending on the make and model of the loudsp eaker, a typical driver can easily set you back $150 or more , so replacing them can be a very expensive exercise - more so than getting the amplifier repaired, in fact. And don 't think that the above scenario in quite improbable. Audio amplifier output stages can go short circuit for a variety of reasons ranging from power supply faults to straight out user abuse. Another way of damaging your loudspeakers is to overdrive them, either by running the amplifier into clipping or simply by advancing the volume control too far. This type of abuse can quickly burn out a tweeter voice coil due to excessive power dissipation In severe cases, it's also possible to damage other drivers in the enclosure, particularly if the amplifier output power greatly exceeds the rated power of the loudspeakers. This project is designed to protect your expensive loudspeakers if any of the above situations occur. In use, the Loudspeaker Protector monitors the DC conditions at the output of the amplifier and trips a relay to disconnect the loudspeakers if a problem is detected. Switch-on thump All the parts for the Loudspeaker Protector are mounted on a small PC board which is installed inside the amplifier chassis. This is the DC-powered version. 62 SILICON CHIP Another problem with many amplifiers is that they cause a large thump in the loudspeakers when they are switched on or when they are switched off. There are a couple of reasons why this can happen. First, the positive and negative supply rails may not rise (or fall) at the same rate and so the output swings towards one rail. Second, it takes a finite time for the input circuit to stabilise at switch on and gain control over the output stage. During this time, there is no negative feedback which again means that there is nothing to stop the amplifier swinging towards one of the supply rails. - ~ - ----- - --- - - - -, I '------+--<> TO LEFT SPEAKER FROM AMPLIFIER LEFT CHANNEL \ \ .----.- -...-----'Wt'lr-:,~--~--.---v. 100 01 02 270k \ + 16VW+ 470 + 25VWJ \ 56k 56k 2x1N914 I 47k RLY1 12V 160ll .,. TO RIGHT SPEAKER FROM AMPLIFIER RIGHT CHANNEL 22k 0.5W ,.. .., B EOc VIEWED FROM BELOW 22k o.sw 22k 47 BP! Fig.1: most of the transistors in the circuit function as switches. Normally, Q4, Q5 & the relay are on & the loudspeakers are connected to the amplifier. However, if a DC voltage appears at an amplifier output, then either Q3 or Q1 & Q2 turn on & Q4, Q5 & the relay turn off. D1, D2 & Q6 form the overdrive protection circuit. 47 BP! ~ 22k .,. BCE 04 1N4002 FROM AMPLIFIER .,. *R1 REQUIRED FOR~+45V LOUDSPEAKER PROTECTOR This project neatly eliminates the switch-on thump problem. It does this by using a simple time delay circuit to switch on a relay to connect the loudspeakers two seconds after power is initially applied. During this period, the amplifier has time to stabilise so that, when the loudspeakers are connected, no switch-on thump occurs. The Loudspeaker Protector can also eliminate any thump that occurs in the loudspeakers shortly after switch off. It can also reduce (but not totally eliminate) the sharp click that some amplifiers produce at the instant of switch off. This can usually be eliminated by correct selection of the suppression capacitor associated with the on/off switch. How it works Take a look now at Fig.1 which shows all the circuit details. The main part of the circuit uses six transistors, most of which function as simple switches. It is based on a circuit which was first used in a commercial Japanese amplifier some 20 years ago. We have added a number of features to it to arrive at the circuit presented here. Transistor Q5 controls the relay and is in turn controlled by Q4. When Q4 is on, it turns on Q5 and the relay to connect the loudspeakers to the amplifier. Base hias for Q4 is derived from a network consisting of a 2 70kQ resistor, two 56kQ resistors and a 100µF capacitor. When power is applied, the 100µF capacitor charges via the 270kQ resistor and, after about two seconds, provides sufficient forward hias to turn on Q4. Q5 and the relay then turn on to connect the loudspeakers at the end of this 2-second delay, thus eliminating any switch-on thump. Q1, QZ & Q3 are used to monitor the amplifier outputs for DC fault conditions. Both channels are monitored via a low pass filter consisting offour 22kQ resistors and two 47µF bipolar capacitors . This filter is there to ensure that legitimate AC signals at the ampl ifier outputs have no affect on the protector circuit. However, if the DC output of th e amplifier rises above +2.5V, Q3 turns on and pulls the base of Q4 low. Q4 thus turns off and so Q5 and th e relay also turn off to disconnect the loudspeakers. On the other hand, if the amplifier output exceeds -2 .5V, Ql 's emitter is pulled negative with respect to its base. Ql thus conducts and turns on QZ which th en turns off Q4, Q5 and the relay as before. Note that when the relay is de-energised, the moving contacts are shorted to the loudspeaker ground lines via the " unused" contacts . This has been done because if a large DC voltage appears at the amplifier output, an arc can be maintained across the contacts as they open; ie, the loudspeakers will still effectively be connected during this time. Shorting the moving contact to speaker ground removes any DC voltage across the loudspeaker terminals and blows th e amplifier fuses if the arc persists. The fact that this Loudspeaker Protector is intended for use with high power amplifiers which can produce considerable output currnnts, plus the JUL Y 1991 63 .IJ~TO LEFT ~--:-1:~r------~--~--~-~- FROM AMPLIFIER 2-n___ .04 ! 0B63VW ~ ~ d:;® ~ ~ \I -Dl[}-- ~a®' efM 10uF8+ 01 ~.---~ ~~:: + - TO RIGHT SPEAKER + FROM AMPLIFIER RIGHT CHANNEL Fig.2: here are the assembly details for the DC-powered version. Be sure to observe correct component polarity & use heavy-duty cable to connect the loudspeaker terminals & amplifier outputs. Resistor Rl (220Q 5W) can be replaced with a wire link for supply rails of less than +45V. need to protect against heavy DC fau lt currents, means that a heavy duty relay is call ed for. The one specified for this circuit has DPDT (changeover) contacts rated at 10 amps. Lesser rated relays can be expected to weld their contacts together under DC fault condition s. DC input voltages of less than Z.5V have no affect on the circuit. This is desirable since all direct-coupled amplifiers have a "normal" DC offset at their outputs and this can be as high as Z00mV or so. In any case, DC voltages of less than Z.5V are not going to cause damage to your loudspeakers. Overdrive cutout D1 , DZ and Q6 form the overdrive monitoring ci rcuit. In operation, D1 & DZ rectify th e AC signals at th e ampli- fier outputs and charge a 10µF capacitor. If the AC signals exceed a preset level , sufficient vo ltage will be developed across this 10µF capacitor to forward bias Q6. Q6, Q4 and th eir common 100Q emitter resistor form a Schmitt trigger. In order for Q6 to turn on, the voltage on its base must exceed the voltage on the base of Q4 (approx. 1V). When this happens due to excessive signal drive, Q6 turns on and Q4 , Q5 and the relay all turn off. As soon as Q6 turns on , the voltage across the 100Q emitter resistor drops since all current is now supplied via the 56kQ resistor in the co ll ector circuit. This means that the voltage on Q6's base must drop to well below the turn-on value for Q6 to turn off again. This translates to an inp ut h ysteresis level of about 3V AC and prevents relay chatter at the transition point. Trimpot VR1 allows the trip point to be adjusted to the desired signal level. Power supply Power for the circu it can be derived in one of two ways . Assuming that you intend mounting the circuit inside your amplifier, power can be derived from any convenient positive DC rail ranging from +30V to +65V. This voltage is fed to a series regulator circuit based on D4 , ZD1 and Q7 . D4 protects the circuit against reverse polarity voltages, while ZD1 sets the voltage on the base of Q7 to 18V. Q7 functions as an emitter follower and produces a regulated +17.4V which is then used to power the rest of the circuit. Also shown on the circuit is current limiting resistor R1 (ZZ0Q) . This resistor is only required if the supply rail is greater than 45V and is linked out for voltages below this figure. The alternative power supply uses a centre-tapped mains transformer to drive a full-wave rectifier made up of diodes D5 & D6. The resulting 17V DC supply is then filtered using a 470µF Z5VW capacitor (n ear Q5 , at the top righthand corner of the circuit). Construction All the parts for the Loudspeaker Protector are mounted on a PC board coded SC0l 105911 and measuring 134 x 71mm. Before installing any of the parts, carefully inspect the copper side of the board for possible defects. In particular, look for open circuit tracks or tracks which are shorted together due to incomplete etching. Two versions of the Loudspeaker Protector can be built, one incorporating the voltage regulator components (based on D4, ZD1 & Q7) and RESISTOR COLOUR CODES 0 0 0 0 0 0 0 0 0 64 No Value 4-Band Code 5-Band Code 1 2 2 4 2 270kQ 56kQ 47kQ 22kQ 2.2kQ 220Q 100Q 68Q red violet yellow gold green blue orange gold yellow violet orange gold red red orange gold red red red gold not applicable brown black brown gold blue grey black gold red violet black orange brown green brue black red bro"".'n yellow violet black red brown red red black red brown red red black brown brown not applicable brown black black black brown blue grey black gold brown SILICON CHIP PARTS LIST 1 PC board , code SC01105911, 134 x 71mm 1 24V centre-tapped mains transforme r**, Altronics M2854 or similar 1 12V DPDT relay with 10-amp contacts, Jaycar SY-4065 or DSE P-8014 1 TO-220 mini heatsink~ 1 5kQ horizontal mount trimpot 1 1-metre length 32 x 0.2mm hook-up wire Semiconductors In most cases, you should be able to mount the PC board on the rear panel of the amplifier, close to the loudspeaker terminals. This view shows the prototype installed on the rear panel of the SILICON CHIP Studio 200 power amplifier. the other using the mains sup ply. For this reason, we have shown two separate wiring diagrams (Fig.2 & Fig.3 ). Fig.2 shows the assembly details for the version with th e on-b oard vo ltage regulator. Th is is th e version to bui ld if you intend powering the unit from the amplifier's pos itive supp ly rai l. Begin the assembly by install ing PC pins at all the external wiring points , then install the resistors , trimpot, diodes and capacitors. Make sure that all the diodes and polarised electrolytics are oriented as shown on Fig.2. The two 47µF bipolar electrolytic capacitors can be installed ei ther way around. Note that the wirewmm d res istor Rl (220Q, 5W) is required only if the supp ly rail is greater than +45V. Mount the resistor so th at it sits slightly above th e board surface to all ow air circulation for cooling. The six small- signal tran sistors can be in stalled next. Push them down onto the board as far as they w ill comfortably go before so ldering the ir leads and check th e ori entation of each one carefully against the wiring diagram. Make sure also that you don't get the transistor type numbers mixed up. Fig.1 shows the transistor pin out detai ls. The BD649 transistor (Q7) is mounted flat against the PC board and fitted w ith a small U-shaped heatsink to keep it cool. To mount th e transistor, first bend its leads at right angles so that the metal tab lines u p with its mounting ho le. Thi s done, smear the tab with heats i nk compound, then bo lt the assemb ly to th e board and solder the leads. Finally, th e relay can be mounted on the PC board. The best way to go about this is to first solder a short length of stout tinned copper wire to each relay pin. Th ese wire leads are then pushed through the relay mounting ho les and soldered. Be sure to sit the relay down as far as it wi ll go, so that its pins contact the board surface. Don 't try to enlarge the board h oles to directly accept the relay p ins. You will damage the copper pattern if you do. Fig.3 shows the assemb ly details for the alternative AC-powered version . It is similar to the prev ious version but omits the vo ltage regul ator components and substitutes the transformer and diodes D5 and D6 instead. Alternative ly, if th e amp lifi er's power transformer has a 24 V centretapped winding, you can use this instead. The completed board assembly can be installed in any conven ient location in the amplifier chassis , although it's best to mount it close to the loud speaker termina ls. In most cases, you shou ld be ab le to mou nt the board on the rear panel using standoffs. If you are installing the AC-powered vers ion into an integrated amplifier, be sure 4 BC547 NPN transistors (01 ,03,04,06) 1 BC557 PNP transistor (02) 1 BC327 PNP transistor (05) 1 80649 NPN transistor (07)* 2 1 N4148 s ignal diodes (01 ,02) 4 1 N4002 diodes (03 ,04* & 05**, 06**) 1 18V 500mW zener diode (ZD1 )* Capacitors 1 470µF 25VW PC electrolytic 1 100µF 63VW PC electrolytic* 1 100µF 16VW PC electrolytic 2 47µF 50V bipolar PC electrolytic 1 10~1F 16VW PC electrolytic Resistors (0 .25W, 5%) 1 270k.O 2 56kQ 2 47kQ 2 22kQ 2 22k.O 0.5W 1 2.2kQ 1 2.2kQ 1W 1 220Q 5W* 1 100Q 1 68Q 1W Miscellaneous Heats ink compound , standoffs, machine screws & nuts , mainsrated cable. * DC-powered version only. ** AC-powered version only. to keep the mains transfo rmer away from th e sens itive preamp lifier stages . On ce the un it has been moun ted in position, connect up the power sup p ly w irirrg but don' t co nn ect the amplifier or loudspeaker leads unti l the unit has been tested . You w ill have to check your amp li fier 's circuit d iagram fo r a su itable DC supply rail and th is shou ld be verified using a m ult imeter before it is connected to the Lou dspeaker Protector. If the AC-powered vers ion is used, JULY 1991 65 FROM AMPLIFIER T"-J - AMPLIFIER TO LEFT .----------J ~ SOLLJtR _ / / ~ ~::: ' S ' DV 06 ~ ij~ 8~~ ~ ~ ~\I -L.=!!......J- ~ 0,.,.o e,:Fes• .... ~~$~ ~ ~~"'1\ ~ ~e--(ill]--e 1 !70u: POWER TRANSFORMER LEFT CHANNEL o~ ~ ~ ~ • VR1 ~ • • • RELAY ~ + - TO RIGHT SPEAKER + - FROM AMPLIFIER RIGHT CHANNEL Fig.3: the alternative AC-powered version omits the on-board voltage regulator components and substitutes a mains transformer & diodes D5 & D6. tery. Connect the battery across each input in turn, first with one polarity and then the other, and check that the relay immediately opens in all four cases. In each case, the relay should close again as soon as the battery is removed. If you strike trouble , switch off immediately and check the circuit for w iring errors. In particular, check the power supply voltage and ch eck that all parts are correctly oriented and in their correct locations. Assuming everything is OK, VR1 can now be adjusted to set the signal overdrive trip point. To calculate this trip point, you need to know the power rating (P) and impedance (R) of your be sure to in stall the mains wiring in et professional manner. Use mains-rated cable and solder the leads directly to the PC board. Do not use PC stakes for mains terminations. Noto also that a lead must be conn ected -from the ground pin on the board to th e main earth of the amplifi er. On no account shou ld you simply connect the ground pin to circuit earth. You could get a hum loop if you do. Testing To test the unit, switch on and check that the relay closes after about two seconds. Fault conditions at the input can now be simulated using a 9V bat- Fig.4: here is an actualsize artwork for the PC board. Note that the same pattern is used for both the DC-powered & ACpowered versions. Check your board against this pattern before mounting any of the parts. rI O 0 0 sco I 10591~ I~' 66 SILICON CHIP Liz· loudsp eakers . These values are then plugged into the formula P = v ~/R to derive th e trip point voltage. For example, let's say that yo ur loudsp eakers have an impedance of 8 ohms and are rated at 50W. If those values are substituted into th e above formula, we get a trip point voltage of V = 20V. Similarly, if your loudsp eakers are rated at 100W, the trip point voltage will be 28V. Th e adjustment-procedure i_s as follows: (1). Switch offal! equipment & connect the Lauds poaker Protector between the amplifier outputs and loudspeaker terminals using h eavy duty (32 x 0.2mm) hookup wire. Disconn ect th e loudspeake~ . (2). Connect your multimeter to the speaker terminals of the amplifier and set it to the 50V AC range. Connect an audio signal gen erato r to an input of the amplifier and sot VRl on the protector board to minimum (fully anticlockwise). (3). Switch on, set the signal generator to 50Hz and increase th e signal level (or volume contro l) until the multimeter shows the required trip voltage. Adjust VRl slowly until th e relay trips (opens). If you wish , the can check the hysteresis of the system by now reducing the signal level and noting the voltage at which the relay closes again. The difference will probably be about 3V although individual units can vary from this figure somewhat. That's it! Your expensive loudspeakers are now protected against signal overdrive and amp lifi er failure. SC Telecom would like to help you develop it. Telecom Australia wants to encourage entrepreneurs and inventors working on ideas relevant to telecommunications and related fields in Australia. That's what the Telecom Product Development Fund is all about. Already the Fund has supported the ideas of people from many local companies. Companies like Almos Systems from Perth, Security Domain from Sydney, Power Reflex from Adelaide and Teletech from Melbourne. These were ideas that might otherwise have languished or been lost to other countries. Many of the ideas which have been supported are also ad~.ing to Telecom's efficiency and effectiveness and, in some cases, are earning valuable export dollars. Any company or individual looking for an opportunity to get their ideas up and running should contact Telecom soon. Not only is financial help available for viable ideas, but Telecom can also provide support with technical and marketing know-how. If you'd like to know more about the Telecom Product Development Fund, call Telecom's Technical Liaison Office on 008 033 673 or send in the attached coupon. = Telecom Australia r-----------------, I I I I I I I L I I I I I I I Please send me an information package NAME COMPA NY ADDRESS POSTCODE Send to: John Moran Telecom Product Development Fund 18 th Floor, 518 Little Bourke Street, Melbourne. 3000 CC040/COZ ----------------- J =fillflJIIIIJI/ flJll/!1- - PART 2 Last month, we introduced our new 4-Channel Dimmer and gave the circuit and operating details. This month, we show you how to build it and list a brief troubleshooting procedure. By JOHN CLARKE Building the SILICON CHIP 4-Channel Dimmer is a straightforward job although it must be done exactly to .our instructions. Part of the circuitry in this device is powered directly from the mains and therefore must be regarded as potentially dangerous. That's not to say that the dimmer is dangerous to use; it's not. The wiring all conforms to the relevant safety regulations and you will have no problems provided you follow the three wiring diagrams to the letter. OK, with that out of the way, let's get down to the construction details. As shown in the photographs, the project is built into a metal case with a sloping front panel. All the operating controls are mounted on this front panel, while the four mains sockets are mounted in a row on the rear panel of the unit. Inside the case, most of the parts are mounted on two PC boards. The main board is coded SC10106911 (201 x 158mm) and is mounted on standoffs on the bottom of the case. It holds most of the parts, including the four toroids and the insulated-tab Triacs. The second board accommodates the six pushbutton switches and is mounted on the lid of the case, along with the slider pots and the power switch. This board is coded SC10106912 and measures 160 x 67mm. To simplify the wiring, the two boards are connected together via two cable assemblies which plug into 8way header pins. These allow the case to be opened up to provide access for servicing, should it ever be needed . We envisage that readers will be constructing the 4-Channel Dimmer from a kit. This is because the metal case is not a standard unit and requires numerous cutouts for the slider pots and switches. However, there's nothing to stop you from making your own metalwork if you already have most of the parts. By the way, at least two retailers will be supplying kits for this project. Both have indicated that the metalwork will be supplied fully punched, with screen printed labelling on the front panel. Board assembly The switch PC board carries the six pushbutton switches, the two right-angle pin headers & a few wire links. There are also four PC stakes, to terminate external connections from the sliders. The LEDs are part of the switches. 68 SILICON CHIP Before starting construction, check the two PC boards carefully for manufacturing defects. You can do this by comparing them with the published patterns. Check the hole sizes in the boards as well. The corner mounting holes on both PCBs should be 4mm diameter, as should the four ·mounting locations for the toroids. The smaller switch board can be assembled first - see Fig.7. Begin by running in the same direction, as this makes it easier to check the board later on. Take care to ensure that all the ICs are oriented correctly (note: IC3 faces in the opposite direction to the others) . Similarly, take care with the orientation of the diodes and be sure to use the correct device at each location. The type numbers can be checked from the parts list published in Pt.1. In particular, note that ZD1 is a 10V 1W zener diode. Now install the capacitors, transistors, 3-terminal regulator (7812), trimpots and the two 8-pin headers. Note that two different transistor types are used. The parts list again shows the type numbers while the circuit diagram (Fig.3) shows the device pinouts. Install the 3-terminal regulator with its metal tab towards the adjacent 2.2kQ resistor. Toroids To make construction easy, it's best to purchase a complete kit with a screen printed front panel & pre-punched metalwork. Be sure to follow the wiring diagrams exactly, as some of the circuitry operates at mains potential. l 1 1 • 1 l 1-LED47 A--(}-K TO WIPER VR1 TO WIPER VR2 IQ l TO WIPER VR3 TO WIPER VR4 Fig.7: parts layout for. the switch PC board. The parts labelled "A" & "B" are the two right angle pin headers. Install them with their pins facing outwards. installing PC stakes at the four external wiring points, then solder in the wire links. A worthwhile tip here is to stretch the link wire slightly between two sets of pliers before installation, so that the wire is nice and straight. Once the links are in, the six plastic switches can be installed. Be sure to push the switches all the way down so that their diagonally-opposed plastic locating pins fit into the holes in the board. Finally, solder in the two right angle pin headers, with the pins facing outwards. The main PC board can be tackled now. Fig.8 shows the parts layout for this board. As before, start by installing the PC stakes and wire links. PC stakes are used to terminate the Triacs and at all external wiring points except for the Active input from the mairis terminal block. Do not install the three wire links shown immediately behind the toroids (L1-L4) at this stage. These links are at Active mains potential and are installed later, using mains-rated insulated cable. Next, install the resistors, diodes and ICs. It's a good idea to install the resistors with their colour codes all The toroids are wound using 18 turns of 0.8mm enamelled copper wire (ECW). First, cut the 4-metre length of wire supplied into four 1metre lengths, then straighten each wire by stretching it slightly. This done, wind each toroid in turn by first passing 500mm of wire through its centre and winding on nine turns. The remaining nine turns are then wound using the other end of the wire , to make up the required 18 turns. Once all four toroids have been wound, they can be installed on the PC board. To do this, feed the leads through the appropriate holes, strip away the enamel and solder them to the board. The toroids are then secured on the board using a screw, plastic washer and nut. You can use transistor insulating bushes for the washers. The three mains-Active links immediately behind the toroids can now be installed. Use mains-rated cable for this job and solder the leads directly to the board . The Active input lead is also soldered directly to the board and.should be left about 100mm long for ultimate connection to the mains terminal block. Triac installation The four Triacs are bolted to the bottom of the case with their leads bent up and across to fit over the PC stakes on the board - see Fig.9. First, bend each lead upwards at right an]UL Y 1991 69 CH2 CH1 CH3 ACTIVE ACTIVE 1 ACTIVE ·TRIAC3 IAC2 •G oi. I .r:i'ill!/~ IC2 M33 ---c::>--t' 07 Fig.8: the parts layout for the main PC board. The type numbers & pinouts for the semiconductors are shown on the main circuit diagram & in the parts list (see Pt.1). Take care with component orientation & note that the three links behind toroids L2, L3 & L4 must be run using insulated mains cable. gles exactly 3mm from the Triac body. This is best done by using long-nose pliers to hold the lead close to the Triac body and then pushing the lead upwards. Once the leads have all been bent, the Triacs can be temporarily bolted in position and the PC board secured on 6mm standoffs. This done, mark the Triac leads where they intersect the top surface of the board, then remove the Triacs and bend the leads at right angles again. Finally, check that each Triac can now be slid over its PC stakes and that the hole in its metal tab lines up with the hole in the case. Note that the hole in the gate lead of each Triac is narrower than the others. This means that the corresponding PC stakes will have to be narrowed by squeezing them with 70 SILICON CHIP pliers until the gate leads fit. The metal tabs of the Triacs can now be smeared with heatsink compound and the Triacs permanently bolted to the case. Note that because insulated-tab Triacs are specified, no insulating bushes or mica washers are necessary. Solder all the Triac leads, then trim the ends of the PC stakes to reduce the possibility of accidental contact. Once the Triacs are in position, the power transformer, mains terminal block and earth lug can be installed. If the case has been anodised, scrape away the anodising from around the earth lug mounting holes to ensure a good electrical contact. Front panel At this stage, you can start mount- ing the various items of hardware on the case lid. Begin by installing the eight slider pots. These are mounted on the 9mm spacers which are attached to the pots using the 3mm grub screws supplied. To attach a spacer, first screw the grub screw about halfway into the slider pot hole, then screw the spacer onto the remainder of the grub screw and tighten. A problem that sometimes arises here is that the grub screw continues to turn in the slider pot when you attempt to screw the spacer on. If this happens, the thn,ad of the grub screw can be slightly damaged over half its length using pliers and this damaged end then screwed into the pot. This should create sufficient friction to prevent the grub screw from turning when the spacer is screwed on. After all the spacers have been installed, the pots can be secured to the front panel using the 3mm countersunk dress screws. Note that the pots ' ·-~f, ,~ . The main PC board is secured to the bottom of the case on 6mm standoffs, along with the power transformer & mains terminal block. Note that the circuitry behind the MOC3021 optoisolators operates at mains potential. This includes the MOC3021s themselves, plus the toroids, 680Q resistors & 0.22µF capacitors. can be mounted either way around , although it's best to orient them all the same way for the sake of consistency. Next, install the knobs and check that they all slide up and down without fouling the slots in the case. Before mounting the switch board, the four leads that go to the wipers of VR1-VR4 must be soldered to the PC stakes. Use a 10cm length of 4-way rainbow cable for this job. This done, the switch board can be attach ed to four 9mm spacers which are secured to the front panel using countersunk dress screws. Note that an insulating washer must be installed under the mounting screw The switch PC board & the eight slider pots are all mounted on the case lid on 9mm spacers. An insulating washer must be installed under the board mounting screw at lower left to prevent it shorting out the adjacent copper tracks. JULY 1991 71 This close-up view shows how the Triacs are mounted, with their leads bent up & across so that they fit over the PC stakes soldered to the main PC board. Because insulated-tab devices are specified, the Triacs are bolted directly to the case without insulating hardware. adjacent to VR8, to prevent it shorting out adjacent PC tracks. Now check that all the switches operate freely. If they don't, you can reposition the PC board by slightly enlarging its mounting holes. The remaining items of hardware Mains wiring CAPACITOR CODES D D D D D D except for the mains sockets can now be installed in the case. These include power switch S7, the rubber grommets, the fuseholder and the earth lugs. The cord grip grommet can also be used to anchor the mains cord at this stage. Be sure to leave sufficient mains cord inside the case to reach power switch S7 (about 10cm). Value IEC Code EIA Code 0.22µF 0.1µF .039µF .01µF .001µF 220n 100n 39n 10n 1n 224 104 393 103 102 Fig. 9 shows the chassis wiring details. Note that you must use mainsrated cable for all wiring to the mains sockets, mains terminal block, fuse , power switch and earth lugs. To conform to the relevant standards, use brown wire for the Active connections, blue wire for the Neutral con- nections, and green/yellow wire for the earth connections. Do not use the green/yellow wire for anything other than the earth wiring. If you do, it could create an extremely hazardous situation for someone else should the unit require servicing later on. Begin the mains wiring by installing the wiring to the Neutral and Earth terminals of the mains sockets. These terminals are connected together in daisy chain fashion, with the :various leads passing through rubb er grommets. Twist the ends of the leads together before attaching them to the mains sockets and don 't leave out the grommets - they are vital safety components. Four 130mm-long leads can now be connected to the Active terminals of the sockets, and the Neutral and Earth leads connected to the righthand socket (as shown in Fig.9). The Neutral lead can initially be made about 150mm long. Once this has been done, the mains sockets can be bolted to the rear panel. The mains wiring is now completed with the lid of the case sitting upright on the mains sockets, .immediately behind the bottom of the case. Use plastic cable ties to lace the wiring together as shown in the photographs. By the way, it's a good idea :o unbolt the earth lugs when solde,mg leads to them. If they are left in situ, the case acts as a heatsink and you will find it difficult to make a good solder joint. The power switch (S7) and fuseholder should both be sleeved with heatshrink tubing to prevent accidental contact with the mains. This means that you have to push heatshrink tub- RESISTOR COLOUR CODES D D D D D D D D D D D D 72 No. Value 4-Band Code (5%) 5-Band Code (1%) 4 3 2 470kQ 100kQ 47kQ 22kQ 10kQ 5.6kQ 3.3kQ 2.2kQ 1kQ 680Q 220Q yellow violet yellow gold brown black yellow gold yellow violet orange gold red red orange gold brown black orange gold green blue red gold orange orange red gold red red red gold brown black red gold blue grey brown gold red red brown gold yellow violet black orange brown brown black black orange brown yellow violet black Dd brown red red black red brown brown black black red brown green blue black brown brown orange orange black brown brown red red black brown brown brown black black brown brown blue grey black black brown red red black black brown 11 4 1 4 7 8 SILICON CHIP ing over the wiring leads before they are soldered to their respective terminals. The heatshrink tubing is then pushed over the body of the component and shrunk using a hot air gun. Do not connect the mains input lead from the PC board to the terminal block at this stage. Instead, tape the end of the lead down out of the way so that it cannot possibly short anything out. That way, the low voltage circuitry can be safely tested before the Triac section of the circuit is connected to the mains. Low-voltage wiring <at> , SWITCH PCB I I I I C D t( VRB VA) I I I I I I I I I I I I I I I {( , , ' I I I P1• I <ID -1 • I I r;;-1• K The low-voltage wiring is straightforward. Begin by connecting the leads from the switch PC board to the pot wipers , then link the relevant pdt terminals together using tinned copper wire. This done, the leads between the pots and the main PC board can be run using rainbow cable. Route the cable so that it runs down the lefthand side of the case as shown in the photos. The two sets of 8-way pin headers (A and B) are also wired using rainbow cable. Two identical cables, each about 25cm long, are required and these are terminated at both ends using 8-way header sockets. To do this, first strip back the ends of the wires and crimp the header pins to them using pliers. The connections are then soldered, the crimp lugs bent over the lead insulation and the ends pushed into the socket shells using a small screwdriver until they click into place. Make sure that you plug the cables in the correct way around, as shown in Fig.9. The "1" side of the A socket on the main board must connect to the "1 " side of the A socket on the switch board and similarly for the B cable. VR2 VR3 VR4 I L G VR1 , VR5 VR6 :- • I ~ REAR MAIN PCB Test & adjustment Before applying power to the unit , carefully check all wiring and the PC boards for correct parts placement. In particular, check the mains wiring to ensure that the unit is safe and check that there are no shorts between mains Active and the chassis. If everything is OK, apply power and check the supply voltages on the ICs. To do this, clip the negative lead of your multimeter to the metal tab of the 7812 regulator (note: the circuit earth is not connected to the case) E• Do •H •G BASE Fig.9: here are the chassis wiring details. Note that all wiring to the mains sockets, mains terminal block, fuseholder, power switch (S7) & earth lugs must be run using mains-rated cable. Do not connect the Active lead from the main PC board to the mains terminal block until the low voltage circuitry has been tested, as described in the text. ]ULY 1991 73 ff 0 and measure the voltage at pin 4 of !Cl; pin 3 ofICZ & IC3; pin 14 ofIC4, IC6 & IC7; and pin 16 of IC5 & IC8. These pins should all be at +12V. If the voltage measured is not between +11.5V and +12.5V, switch off immediately and check that the !Cs and regulator are all correctly oriented. 74 SILICON CHIP If these are OK, check the board for shorts or open circuit tracks. Assuming everything is OK, the 10V supply for the Channel Master, Flash Master and Chaser Master controls can now be set. Connect your multimeter between the tab of the 7812 regulator and the top of the master controls (VR5 , VR6 & VR7) ; ie, to point G. Adjust VR9 for a meter reading of +lOV. The unit is now ready for an operational test but first switch off and fit the lid to the case. To check the unit , just following these step-by-step instructions: (1). Set all the sliders to minimum and apply power. Initially, the Chaser LED should be off. Push the Channel Master control fully upwards and check that the channel LEDs light (and increase in brilliance) when the Channel Level controls are advanced. Check that the Channel Master pot controls the overall brightness of the channels. (2). Set the Channel Master control to minimum and press the Channel Flash switches. Check that the channel LEDs light to the brightness set by the Flash Master control. (3). Press the Chaser switch and check that the Chaser LED lights. The Single Step LED should flash at the rate set by the Chaser Rate control. Check that the Channel LEDs chase at the rate set by the Chaser Rate control and that their brightness can be varied by the Chaser Master control. (4). Set the Chaser Rate control to minimum. Check that the Single Step LED goes out and that the chaser action stops. Now check that the Single Step control can be used to step through the chase sequence. The Single Step LED should light each time this switch is pressed. (5). Press the Chaser switch again and check that the chaser operation halts and that the Chaser LED goes out. Preheat setting Assuming everything checks out so far, switch off the unit and pull the plug from the mains outlet. Now open the case again and connect the Active lead from the main PC board to the Use plastic cable ties to lace the wiring at several points to ensure that everything it kept neat & tidy. Pay particular attention to the mains wiring & use your multimeter to check that there are no shorts between mains Active and the case before switching on. Also, check that the earth lugs make good electrical contact with the case (scrape away the anodising if necessary). rJ .. 0 6 1 SC 10106912 0 o_j Fig.11: this is the full-size artwork for the switch PC board. ]ULY 1991 75 The 4-Channel Dimmer can control anything from 40W light bulbs to high power spotlights like those shown here. Note that although each channel can control a load of up to 2400W, the maximum lamp load for the unit is 3600W. terminal block. When this has been done, the preheat setting can be adjusted as follows: (1). Connect a light to one of the channels of (eg, a 100W light bulb or 500W spotlight). Apply power and check that its brightness can be controlled using the Channel Master control and the re levant Channel Level control. (2). Set the Channel Master control to minimum and adjust VR10 so that the lamp just glows a dull orange. This is the setting for the filament preheat voltage. The 4-Channel Dimmer is now ready for use. Disconnect power (ie, pull the plug from the wall socket) and secure the lid to the case with self-tapping screws. If it doesn't work The fuseholder & the power switch are sleeved with heatshrink tubing to guard against accidental contact with the mains. Use a hairdryer to shrink the tubing over these components. 76 SILICON CHIP Most project problems are caused by faulty soldering, incorrect component placement and wiring faults. If you run into problems, check these three things first. In particular, try to isolate the fault to a specific part of the circuit and then relate this to the PC boards. Often, a visual inspection is not enough to detect a problem and running a sharp knife between suspect tracks can sometimes eliminate a short circuit. For more specific problems, check the following troubleshooting guide. (1) . Power switch neon does not light and power does not come on: check fuse and switch wiring. (2) . Fuse blown: check wiring to switch , fuse, terminal block and mains sockets. (3). Switch S1-S6 controls not operating correctly: check the A and B cable connections between the two PC boards for polarity and for possible cross connection. (4). Chaser LED switches on but cannot be switched off when the Chaser Master control is at maximum: adjust VR9 to slightly reduce the 10V rail applied to the pots (or use an 11 V 1W zener diode for ZDl) . (5) Chaser Rate control not working: check the connections to VR8 and the resistor values around IC2b. (6). Channel LEDs do not light but some channels will drive lamps correctly: check Q5 and Q6 for correct type numbers (BC547) and check Q1Q4 (BC557). Also, check that the LEDs are correctly oriented in the switches. (7). Channel LEDs operate but not all channels drive lamps: check inductors L1-L4 for bad solder joints. (8). Chaser ON/OFF switch does not latch for Chaser operation: check that pin 13 of IC8 goes high when the switch is pressed, and then goes low again when the switch is released. Also, check that pin 12 is at ground (except when power is first applied to the circuit), and that pin 15 toggles between low and high each time the Chaser ON/OFF switch is pressed. (9). Channel LEDs and lamps fail to operate: use a CRO to check the ramp waveform at the output of !Cl b (pin 8). If no CRO is available, use your multimeter to check the average DC voltage at this point. You should get a reading of about 3.5V. If no ramp is present, check the circuit around ICl b andIC2a. SC DM8135 Multimeter with Bargraph e 3 1/2 digit large LCD display • Memory for relative measurements • Data hold function • Diode and Transistor testing DM8243 Multimeter with Frequency Counter e 4 1/2 digit large LCD display • Measures capacitance • 200kHz frequency counter • Diode and Transistor testing Gotta Gatta 0S7020A 20MHz & 0S7040A 40MHz Oscilloscopes DM8433 Multimeter with Thermometer e 3 1/2/digit large LCD display • Measures capacitance • Measures Temperature -20 to +15ll°C DM6335 Multimeter fits your shirt ·pocket e 3 1/2 digit LCD display • Memory mode for relative measurements • Data hold function • Slim,compact construction GoldStar 0S8020R • High sensitivity- 1mV!div • Stable low drift design • 8 divisions of displayed dynamic range with accurate distortion-free waveform measurement • Special TV sync separation circuits for measurement of video signals • Delayed sweep function (OS7040A ) • ±3% accuracy • Convenient XY operation for measuring phase differences between two waveforms • Variable sweep control incorporating xio magnifier • Uncal and trigger warning lights e TV-V & TV-H triggering • Trigger hold-off _ • Includes TWO x1/x10 switched probes Readout Scope • Cursors for direct measurement of waveform voltage, time and frequency e 20MHz bandwidth • 1mV max sensitivity • Similar performance to OS702[JA ELMEASCO Instruments Ply: Ltd. Australia's Leading Test & Measuring Instrument Company Contact your nearest Elmeasco Office for name of your local supplier and special pricing if you mention this magazine Tel : (02) 736 2888 Fax : (02) 736 3005 NEW SOUTH WALES Tel : (03) 879 2322 Fax : (03) 870 8972 VICTORIA Tel : (07) 875 1444 Fax : (07) 277 3753 QUEENSLAND Tel : (08) 344 9000 Fax : (08) 269 6411 SOUTH AUSTRALIA Tel : (09) 470 1855 Fax : (09) 470 3173 W. AUSTRALIA Silicon Chip BACK COPIES May 1988: Optical Tachomete r For Aeromod ellers; High Energy Ignition For Cars ; Ultrasonic Car Burglar Alarm ; Walkaround Throttle For Model Railroads , Pt.2; Design ing & Building RF Attenuators ; Motorola MC3334P High Energy Ignition IC Data. 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 Tri acs. 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 & Appl ications; What Is Negative Feedback, Pt.4. October 1988: Stereo FM Transmitter (Uses Rohm BA 1404); High Performance FM Antenna ; Matchbox Crystal Set; Electronic House Number; Converting A CB Radio To The 28MHz Band ; Queensland's Powerful Electric Locomotives. November 1988: 120W PA Amplifier Module (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; Electronics & Holden's New V6 Engine; 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. February 1989: Transistor Beta Tester ; Minstrel 2-30 Loudspeaker System ; LED Flasher For Model Railways (uses LM3909); Build A Simple VHF FM Monitor (uses MC3362) , Pt.1 ; lightning & Electronic Appliances; Using Comparators to Detect & Measure. 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 Inter- Use this handy form to order your back copies ---------------------------------Please send me a back issue for: 0 September 1988 0 October 1988 O February 1989 0 March 1989 0 July 1989 0 August 1989 0 December 1989 0 January 1990 O May 1990 0 June 1990 O October 1990 0 November 1990 0 March 1991 0 April 1991 0 0 0 0 0 O May 1988 November 1988 April 1989 September 1989 February 1990 July 1990 o December 1990 0 May 1991 0 0 0 O O O 0 0 July 1988 December 1988 May 1989 October 1989 March 1990 August 1990 January 1991 June 1991 Enclosed is my cheque/money order for $_ _ ____or please debit my: Card No. Signature _ _ _ __ _ _ __ _ _ __ I Card expiry date_ _ J /_ _ Name ____________________ ________ Street _ _ _ _ _ _ __ _ _ _ __ _ _ _ _ _ __ __ __ _ Suburb/town _ _ __ _ _ _ _ _ _ _ __ _ Postcode _ _ _ _ __ 0 Bankcard SILICON C HIP August 1988 January 1989 June 1989 November 1989 April 1990 September 1990 February 1991 I I I I 0 Visa Card 0 Master Card $5.00 each (includes p&p) . Overseas orders add $1 each for postage. NZ orders are sent air mail. Detach and mall to : SILICON CHIP PUBLICATIONS PO BOX 139 COLLAROY BEACH NSW 2097 Or call (02) 979 5644 & quote your credit card details. Fax (02) 979 65o3 ------ -- - ------ --- --- ------ -- 78 0 0 0 O O O 0 l -__ _ x I I ------ -- -------- Digit Counter Module; Voice Mail For Your Computer; Simple Shortwave Converter For The 2Metre Band ; How To Make Dynamark Labels. October 1990: Low-Cost Siren For Burg lar Alarms; Dimming Controls For The Discolight; Surfsound Simulator; DC Offset For DMMs; The Dangers of Polychlorinated Biphenyls; The Bose Lifestyle Music System; Using The NE602 In Home-Brew Converter Circuits. November 1990: Low-Cost Model Train Control ler; 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. ference; LED Message Board, Pt.3; Electronics Fo, Everyone - All Ab~ut Electrolytic Capacitors. TV; Speed Controller For Ceiling Fans; Designing UHF Transmitter Stages. June 1989: Touch-Lamp Dimmer (uses Siemens SLB0586); Passive Loop Antenna For AM Radios; Universal Temperature Controller; Understanding CRO Probes; LED Message Board, Pt.3; Coherent CW - A New Low Power Transmission Technique. 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; A Look At Computer Interfacing. 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; Facts On The PhaxSwitch - Sharing Your Phone Line With A Fax Machine. March 1990: 6/12V Charger For Sealed LeadAcid Batteries ; Delay Unit For Automatic Antennas; Workout Timer For Aerobics Classes; 16Channel Mixing Desk, Pt.2; Using The UC3906 SLA Battery Charger IC ; The Controls On A Model Aircraft. 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. April 1990: Dual Tracking ±50V Power Supply; VOX With Delayed Audio; Relative Field Strehgth Meter; 16-Channel Mixing Desk, Pt.3; Simple Service Tips For Your Microwave Oven; Model Aircraft Aerodynamics ; Active CW Filter For Weak Signal Reception. September 1989: 2-Chip Portable AM Stereo Radio (Uses MC13024 and TX7376P) Pt.1; AlarmTriggered Telephone Dialler; High Or Low Fluid Level Detector (Uses LM1830N); Simple DTMF Encoder (uses Texas TMC5089) ; Studio Series 20-Band Stereo Equaliser, Pt.2; Auto-Zero Module for Audio Amplifiers (Uses LMC669); A Guide To Hard Disc Drives. 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; Electronic Load For Checking Power Supplies. 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 . December 1989: Digital Voice Board (Records Up To Four Separate Messages); UHF Remote Switch; Balanced Input & Output Stages; National Semiconductor LM831 Low Voltage Amplifier IC Data; Install A Clock Card In Your PC; Index to Volume 2 (January- December 1989). 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 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; Digital Waveform Generation Using A Computer, Pt.4; 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 Tel ephone; Remote Control Extender For VCRs; Power Supply For Burglar Alarms; Low-Cost 3- December 1990: DC-DC Converter For Car Amplifiers; The Big E·scape - A Game Of Skill; Wiper Pulser For Rear Windows; Versatile 4-Digit Combination Lock; SW Power Amplifier For The 6Metre Amateur Transmitter; The Green CD Pen Controversy. January 1991: Fast Charger For Nicad Batteries, Pt.1; Have Fun With The Fruit Machine; TwoTone Alarm Module; Laser Power Supply (For Tubes With Ratings Up To 10mW); LCD Readout For The Capacitance Meter; How Quartz Crystals Work; The Dangers When Servicing Microwave Ovens; Electric Vehicles - The State Of The Art. February 1991: Synthesised Stereo AM Tuner, Pt.1 ; Three Inverters For Fluorescent Lights; LowCost Sinewave Oscillator; Fast Charger For Nicad Batteries, Pt.2; How To Design Amplifier Output Stages; Tasmania's Hydroelectric Power System. 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; The Easytune FSK Indicator For HF Transmissions; Playing With the Ansi.Sys File. 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; High-Power DC Transmission Lines. June 1991: A Corner Reflector Antenna For UH F 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. PLEASE NOTE: All issues from November 1987 to April 1988, plus 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. ] ULY 1991 79 CIRCUIT NOTEBOOK Interesting circuit ideas which we have checked but not built and tested. Contributions from readers are welcome and will be paid for at standard rates. 06 1N914 D1 1N914 D3 1N914 D4 1N914 10k 10k 470k 470k 470k 47k 47k IC1 555 PLAYER S1 11 1 + 150VWI ":' ":' 3-team quiz adjudicator Here 's a circuit that will allow you to play your own quiz games and tell who was first to hit the button. The circuit is based on three 555 timer ICs working as monostables. These are connected to three momentary contact pushbutton switches, one for each player. Let's say that switch Sl was pressed fractionally before the others. This triggers ICl, discharging the lµF tim- IC2 555 PLAYER S2 21 ·+ O 1 1 + 150VWI ':' IC3 555 PLAYER 2 LE02 -:- s3 80 SILICON CHIP l 5ovwl 1 + "!" ing capacitor and sending the output at pin 3 high. LED 1 thus lights up to indicate that player 1 was first. The high at pin 3 also turns Ql on, pulling the cathodes of diodes D5 and D6 low. These diodes now conduct, pulling their anodes and the reset pins (pin 4) of the other two 555s (IC2 & IC3) down to about +0.6V. This resets these two 555s so that their outputs cannot possibly go high, thus locking out the other two players. LED 1 remains on for about five seconds and this time is set by the Analog data logging via a PC's parallel port This analog data logger was developed as a result of Steve Payor's series on signal generation using a PC ( see SILICON CHIP, February 1990). It also uses the parallel printer port but in this case, the port is used for input rather than for output. Analog data, in this case rough linear positional information from the wiper of a standard linear slider potentiometer ( shown on the circuit as VRl), was digitised to 8-bit (256 level) resolution using a National Semiconductor ADC0804 AID converter (ICl). Only two other components are used in the circuit: a l0kl:2 resistor and a 150pF capacitor. PLAYER 3, 470kQ resistor and the lµF capacitor on pins 6 & 7. Identical RC timing networks are also connected to 555 timers IC2 & IC3. The circuit works in similar fashion if S2 or S3 is pressed first. To give the circuit a bit more a sparkle, you may like to add the TwoTone Chime Module (SILICON CHIP, January 1991) to the output of each 555 to provide audible indication as well. Darren Yates, SILICON CHIP. +5V 20 INTR IC1 ADC0804 10k 5 087 11 12 D86 13 085 14 084 15 0B3 16 082 17 0B1 18 DBO 4 CLKIN WR 3 AGND 8 CS RD VIN- DGNO 1 2 7 GREY 32 VIOLET 11 BLUE 10 GREEN 12 YELLOW 13 ORANGE 36 RED 31 PC PRINTER CABLE 83 87 86 85 B4 Cl C2 BROWN 14 C1 1 BLACK WHITE co 2 15 ERROR 11 BUSY 10 12 13 17 ACK PE SLCT SLCTIN 16 Ttifi 14 AUTO 1 STB 2 DO 0B25 10 .,. Note that using a slider pot for positional data input will not generally give satisfactory performance in terms oflinearity and hysteresis. However, a more appropriate transducer, continued next page such as a linear displacement transducer, is much more expensive. Strobing was achieved with a lowgoing pulse on pin 3 (WR) of the ADC0804 via a line from port A of the PC's printer port, and the parallel digital output permanently enabled by tying the RD signal on pin 2 low. The data output from the converter was directly connected to the PC with a parallel printer cable. Bit D3 of port B (see Table 1 of Steve Payor's February 1990 article) was assigned for monitoring the AID conversion status (ie, the ADC0804's INTR pin) if needed, leaving bits D4-D7 of port B for input of the most significant nibble and bits D0-D3 of port C for input of the least significant nibble. This hardware arrangement has been tested successfully with a number of XT and AT originals and clones but there may be some with which it doesn't work, due to the wiring of individual ports. Problems have been encountered when attempting to use the device with a laptop anrl also one 386-type PC, which didn't allow input via port C. The sample code listing in Table 1 illustrates typical programming. The software was written using Turbo Pascal version 3, for ease of interfacing with existing data processing routines. Extensive use is made of Turbo Pascal's handy PORT command for 1/0. It is essential to nominate which port (LPT1, LPT2, LPT3) you wish to use, in response to prompts by procedure "select_port". Setting up the port is along the lines discussed in Steve Payor's articles: The procedure "test_ports" is included to establish which port(s) are available on a particular PC by writing logic ones to all lines on port A, and then reading back and comparing. The process is then repeated, this time using logic zeros. "Initialize_port" performs initialization of printer port C for input by writing what is effectively a group of logic ones to the port - actually binary 0100 is written (to bit D3, DZ, Dl, DO). because signals to bits D3 , Dl and DO (but not DZ) must be inverted due to the hardware inverters present. The procedure "strobe_adc " produces the low-going convert command pulse signal required to initiate each conversion by the ADC0804. This procedure first ensures the strobe line is high so that a distinct edge can be produced when it is driven low. It Resistor calculations on a Commodore 64 A program for making up nonstandard resistor values from series and parallel combinations was published in the November 1989 issue of SILICON CHIP. You simply typed in the value required plus the tolerance, and the computer showed you which standard values to use. That program was written in GWBASIC for IBM-compatible machines. The version published here works in exactly the same way but has been modified for use on a Commodore 64. A. Williamson, Elwood, Vic. ($20) l et REM PR OGRAM TO Flf\JD CDMBil'-JATIOl'-l OF Ti,JQ E12 RES ISTORS I N S ERIES OR PARALLEL 26 DATA· 01 , , 012, • 0 15,. 0 18, . 022, • 027, . 033, . 033, , 04 7, . 056, . 068, • 082 30 DATN • 1 , , 12, • 15, • 18, . 22, . 27, . 33, . 39, . 4 7, . 56, . 68, . 82 40 50 60 70 DATAl,1.2,1,5,1,8,2.2,2, 7,3 ,3,3. 5,4, 7,5,6,6,8,8.2 0ATA10,12 , 15,18,22,27,33,39,47,56,68,82 DRTA100,120,150,180,220,270,330,390,470,560,880,820 .DATA 1000 ,120~, 1500,1a00 , 2200,2100,3300,3s00,470e,ssee,sea0,e200 80 DMTA10000,12000,15000,16000,22000,C706 ~,33 000,33000,47000,56000,68000,32000 9P.I DATA 100000 100 DIM E 12 ,: 85): FOR!= 1 T085: READ E 12 ( I ) ; NE)<T I 110 RESTORE 112 PRHIT"'.:.l" 120 Il'lPU"T"CESIREO RESISTANCE( l TO 388.8 ) •• ,. ";R 121 PRINT 122 IFR=0THEl'874 IF R >989.9THEN370 I!'!PUT "l,JJTH IN +/- PER CENT ., ,,, •• "; T !23 1~0 140 A=R•<l - T/ 100):C =R•<!+T/100) 145 PRINT 150 PRINT" A VALUE BETUJEEN ";A; "AND" .!C 155 PRINT"--- - - - ------- -- ---- --------- - " 160 REM FI ND NEAREST c l'-lE i-<:T LO l,JEST ) E 12 VALU E 170 NEARE'?T =25 180 IF E12 (NE AREST+1 ><R T HEN NEAR EST =l'JE AR EST,._l :GOT.Ji80 180 REM TR Y AL L SERIES COMBINATIOl'-lS 2 FOR DEC:AOES LOWER THA~J R 200 FOR I =NE AREST -24TCNEARE ST: FORJ =l',lE AEST-24TO I 2112) Rl=i::12 ( l)+Ei 2(J) : IF Fl <A ORRt>C THEl'-l 240 220 PR I NT CHR$ ( 5) E 12 ( I ) .: " Al\lO " : E 12 ( J); " l N SER I ES, "; 231:! PR! l'-ff CHR$ ( 5) ''TOTAL="E12 ( l )+ E12<J ) ;!:<qe' NE XTJ, I z5e REM TR Y ALL PARALL E L COMBINATIONS FOR 2 DECADES HIGHER THAH R 260 FO R I =1-~EAREST + 1 TO NEAREST +2 5 : F OR J =I\EAREST + l TO 27 0 Rl=l /(1/E12 < I ) -+1/E12<J )) : IF Rl <AOR Rl >C THE~-1 3t3eJ 280 PRIMT CHR:S ( 153) E12(I) ; '"HNO";E12(J); "' It~ PARALLEL, ''; 290 PRINT''TOTAL = " INT~ 1/( 1/E12 < I )+ 1/ E12 (J))) 300 f'.JEXT J, ! : PR J NT" SEARCI-! C.'J:M.0 ~ETE. " I 302 PRP./T~oo YOU W!SH TO COt--JTJr•JUE (Y 0R ~~ ) " .: : Ir•.JPU TA$ 303 PR J: ,!T CHR:t: ( 154 ) Ir+A$ = "Y''-HEI-Jl 12 !FA$ = ''l'l"THE~·l401 304 306 ~7C PRI'iT"E YCEEDS 993.8.RE-RUN,USE DI VISOR" 37 1 PR Ir-JT" :t: :t·** *** :t.:t.:t-*** :t. :t.:t.:+::+:" 373 GOTO400 374 PRINT 375 ?R P•!T" e, HAS NO VALUE,R E-RU H" 27S PRINT" 400 STC 40 ! f'.lEl-' 0 READ Y. then produces the low-going convert command pulse and, finally, returns the strobe line high. Here Turbo Pascal's "DELAY" command was found useful for providing a defined pulse width for the strobe pulse, and also for allowing a delay for conversion. Nominally, the command "DELAY(l)" will provide a one millisecond delay (the minimum delay possible) but this is likely to be a bit shorter, depending on your particular PC's clock speed. It is probably better practice to monitor for an indication of "conversion completed" by polling the INTR pin of the ADC, depending on your application. The procedure "massage_data" inputs the data in the form of the upper four data bits from port B and the lower four bits from port C, masking off the non-valid nibbles of each. The upper and lower nibbles are then reassembled back into the full eight parallel bits which originated from the ADC output. However, due to the inline hardware inverters previously mentluned, several of the bits (D7, D3, Dl, DO) need to be inverted. Fortunately, Turbo Pascal includes JULY 1991 81 Table 1: Sample Code Listing PROGRAM ADC ; (Sample program to input data from ADC 0804 -10 Jan 91) CONST {port addresses:) lpt1 _porta=$378; lpt1_portb=$379; lpt1 _portc=$37a; lpt2_porta=$278; lpt2_portb=$279; lpt2_portc=$2be: lpt3_porta=$3bc; lpt3_portb=$3bd; lpt3_portc=$3be; VAR pot_value ,porta,portb,portc:INTEGER;lpt:CHAR;input:INTEGER; PROCEDURE test_ports; {procedure to identify active parallel port(s) • 10 Jan 911 VAR input:INTEGER;low_ok,high_ok:BOOLEAN; PROCEDURE check_port(lpt:CHAR); BEGIN CASE lpt OF '1':porta:=lpt1 _porta; '2' :porta:=I pt2_po rta; ·3': porta:=I pt3_porta; END; PORT[porta]:=0; input:=PORT[porta]; IF input= 0 THEN low_ok:= TRUE ELSE low_ok:=FALSE; PORT[porta] :=255; input:=PORT[porta); IF input= 255 THEN high_ok:= TRUE ELSE high_ok:=FALSE; IF (low_ok AND high_ok) THEN WRITELN('lpt', lpt,' present') ELSE WRITELN('lpt', lpt, ' not present') END; BEGIN ftest_portl check_port('1 '); check_port('2 '); check_port('3 '); END; PROCEDURE select_port; BEGIN testports; REPEAT WRITELN;WRITELN; WRITELN('Which port will the converter be plugged into?:') WRITE('(Choose 1, 2, or 3, and press enter)'); READLN(lpt); UNTIL lpt IN ['1','2 ','3'); END; PROCEDURE initialize_port; BEGIN CASE lpt OF '1': BEGIN porta:=lpt1 _porta; portc:=lpt1_portc; portb:=lpt1 _portb; the "XOR" command (non-standard Pascal) and these bits can be conveniently inverted by XOR'ing with binary 10001011. As written, the main routine performs the initialization and then enters an "infinite" loop of repeated conversions, displaying the result on the PC screen. The "DELAY(200)" instruction is included to provide a substantial smoothing of jitter between samples. 82 SILICON CHIP END; '2':BEGIN porta:=lpt2_porta; portc:=lpt2_portc; portb:=lpt2_portb; END; '3':BEGIN porta:=l pt3_porta; portc:=lpt3_portc; portb:=lpt3_portb; END; END; PORT[portc]:=4; END; PROCEDURE strobe_adc; BEGIN PORT[porta] :=1 ; {Assert strobe line inactive high I DELAY(1); {Hold stable approx 1 msec.l PORT[porta]:=0; {Assert strobe line active low! DELAY(1); {Allow a strobe pulse width time (approx 1 msec) PORT[porta]:=1 ; {Assert strobe line inactive high } DELAY(1); {Allow ADCOB04 some conversion time before read i END; PROCEDURE massage_data; VAR high_nibble,low_nibble:INTEGER; BEGIN low_nybble:=PORT[portc] AND 15; {mask off high bits} high_nibble:=PORT[portb] AND 240; {mask off low bits} pot_value:=(low_nibble+high_nibble) XOR 139; {form word and invert bits DO,D1 ,D3,D7I END; PROCEDURE convert; BEGIN {convert} strobe_adc; massage_data; END; PROCEDURE display: BEGIN GOTOXY(10,10); WRITELN (pot_value:7); DELAY(200); {smooth the display) END; BEGIN {adcl {main routine - initializes parallel port for input, then loops perpetually - user can break with CTRL-Cl CLRSCR; select_port; initialize_port; CLRSCR; WRITE('Type ' C (CTR L C) to exit'); REPEAT convert; display; UNTIL FALSE; CLRSCR; END. The circuit and software can be used to acquire analog data from other analog voltage sources, but consideration should be given to the band width required for your signal - the software routine here is deliberately longwinded for simplicity and consequently wasteful in execution speed. Throughput can be increased by discarding the software delays in the strobing routine and instead monitoring the INTR pin as discussed above, and using a one-shot to provide a distinct conversion command pulse. Conversion time data for the ADC0804 suggest that the maximum reasonable input signal which could be sampled would be somewhat less than 4kHz, depending on software overheads and what you intend doing with the collected data (eg, writing to disc or plotting on screen). P. Junor, Melbourne, Vic. ($60) WOOD FOR CHIPS... WOOD FOR CHIPS... WOOO FOR CHIPS... WOOO FOR CHIPS...WOOD FOR CHIPS... WOOD FOR CHIPS...WOOD FOR CHIPS... WOOD Connector "Extra Special" Do you use lots 01 uz~ connec1ors? Then take advantage of this bulk buy special - Buy in SO's and you'll pay Lust 70c a connector! That's right D25's male or female (not mixed) are just $35.00 for 50. Backshells to suit $40.00 for 50. (Yes that's 80c each!) Crazy Printer Cable Clearance What are you paying for print&r cables? Around S20? Look at this_ a 2m cable with 90° .Centronics connector fSaves fouling up your paper feed .). Usual D25 plu g at the other end. Our price? Nine dollars fifty_ $9.50. No, we haven't left the '1' out! SerialTest serial data analysis on your PC Now fitted with BOW heater, NEW Hot air nozzle makes it easier to remove surface mount devices. Price is unchanged ai:m 1~~ t~) If you're working on surface mount devices you'll need the SM D Rem ova I I • K•t Comes with filter pipe, stainless steel wire and blade rollshwire holder, blade holder and ot air nozzle. $82.80 ----------------------1 Save P.roblems and Cost w·1th MEMOREX .I GENUINE.. 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Use ve rtical ly or horizontally. , l ~or ~~~~~1nn~~ ·wrong place l $59.95 'U,_e also have the 8 'When itc~mes to using Serial/est to diagnose a practical serial communications set-up, most users will find the package easy-to-drive, yet a powerful diagnostic tool... " Rob Evans f.A. Ma-t 91 The NEW SC5000A DIC Desolderlng Tool. '"" ,s an M~·UOS software and cabling package which enables technicians and engineers to perform serial data comms analysis. It offers sophisticated problem solving facilities at a fraction of the cost of dedicated hardware systems. SerialTest provides a window onto RS232 lines operating either as a passive observer or actively sending d ta t 0 1 · 1 t s m lat ei~he~~rnH o?~it Je$ic~ u e Tri ggers can be defined based on error conditions or data to initiate or terminate mon itoring sequences. • Hand les baud rates up to 115.2kbaud. • View each byte in ASCII or EBCDIC, decoded to hex, decimal , binary or octal c::, ~ :0 2 "6 Why pay up to $150 for a label? Take a close look at APPA mullimeters. Look fam iliar? That's because they' re sold unde r different brand names . And that means you fgu~fJ{ teleo~ ~~rt~~gf t~~\~:ed model sel ling at around S150 more than our price. So you·re paying that much extra just for the brand label! ,,..u 1!1!21 Mi,.1,,•1 'P'• d•11t ~ • ii • the""""~ •"II U:>ITU L o, 1 l 1r <t lctlet ol - • c ho ,~e n.. t [S( I loeoi ,..1 k • •"" lo e , 11 the~,. • Writes captured data directly to disk to allow maximum cap[ure buffer • CRC checksum calcu lations • Auto-configuration to any of the comms ports 1 to 4 • Time-stamping (absolute and relative) including delta time calculafions • Split line DTE over DCE display $395 plus sales tax Send $10 for a demo disk. refundable on purchase. EI k lierman e tro Hobby Drill $45.00 45.00 65.00 99.00 1 $45.00 $65 .00 Custom Cables If you can't find what you want, ws'/1 maks ii for you! Our ssrvics now includss • "D" typs connsctors with shioldsd cab/a • /DC typss onto flat cabls • BNC typss onto coax. Call us for a quota! Power Supplies to go with it. 20,000 rpm!! Value at $99 .50 Ultrasonic Cleaner The latest high-tech wcy to clean PCB 's, switches, watches, drafting pens - even your dentures! Let the millions of tiny cavitation bubbles clean the surface 40000 times per second. 165x90x50mm container holds half a litre and is made of 304 stainless steel. Some people are charg ing a lot more. Our's are only $150 GPQ3020 DC Powe r Supply • z by 3UVflA vanaoIe outputs • Fixed 5V/3A and SV/1A outputs GP03030 o8&a.-:Ai~~wx tax) • 2 by 30V/3A variable outputs • Fixed SV/3A and 5V/1A outputs GPA3030 DCSjl°ga}A(~~Py ex tax) • Single 30V/3A output • Fine/Coarse :ontrol $280.50 ($245 ex tax) Buil1 •m Fliril Lighter AdJUStable h om 10-60W PORTASOL PROFESSIONAL SOLDERING KIT See E.A. April 88. No cords or batteries yet it gives the equivalent of a 10 to 60W iron. Up to 90 minutes continuous use from a single fill. Tip temperatures as high as 400°C can be set. The kit includes one soldering tip, a-hot knife. blow torch and hot blow. Cap contains a flint lighter. Comes in a handy case (with stand for the iron) 79 9 S · " i~~Wi~d2 '1l~W~~D SOLDERING IRON We've sold hun ctreas 01 ·em to servicemen and technicians. Complete .:nd ready to use with just the iron and bit $39 .95 Spare tips are each $12.95 Portasol gas specifica 1Iy designed for PORTASOL 150g $ 5.95 look at tho featuro s • Largo high contrast display· Tho 96 and 98 havo analog bar • !o'ff/:/c~3od input terminals and function switch /or oasy setting • Probe storage clips built in for oas;- /wo handed 11111asuromon/s • Tho 96 is water rosistanco for industrial uso • Shockproof for a drop of 1. 5ml • Bui/1-,n till stand : ftJ~'(7&gc:t,i~~~Jf~1 and Ul/244 standards for safe operation Model 93 • 1999 count • Large 20m m high contrast LCD readou t • 8 Functions - Vdc. Vac. Ade, Aac. Ohms, Diode, Freq uency, car,aci tance • 0.51/, de accuracy Ranges Vdc 200mV, 2V, 20V. 200V, 1OOOV Vac 200mV. 2V, 20V. 200V, 750V Ade 200uA, 2mA, 20mA. 200mA. 2A, 20A Aac 200uA, 2mA, 20mA, 200mA, 2A, 20A Ohms 200n. 2kn. 20kn. ZOOkn. 2Mn. 20Mn Frequency 2kHz, 20kHz, ZOOkHz Capacitance 2nF. 20nF, 200nF, 2µf, 20µF Also available Model 93T v1 :o :·a~s s'.8r :e,,•e· p1ace of 2A •a- ge Modal 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 offse t Ranges Vdc 200mV. 2V, 20V, 200V, 1OOOV Vac 200mV, 2V, 20V, 200v, 750V Ade 200uA. 2mA, 20mA. 2uOmA, ZA, 20A AIJ.c 200uA, 2mA. 20mA, 200mA, 2A, 20A Ohms 200n, 2kn, 20kn, 200kn. 2Mn, 20Mn $166.80 Modol 98 • 3 1/2 digit plus 41 segmen t anal og bar graph • Autoranging or manual selection • 8 Functions - Vdc, Vac, Ade, Aac, Ohms , Diode, Frequency, Capacitance • Data hold • Memory offset aii~~mV, ZV, ZOV, 200V, 1OOOV Vac 200mV, 2V, 20V, 200v, 750V Ade 200uA. 2mA, 20mA, ZuOmA, 2A, 20A AIJ.c 200uA, 2mA, 20mA, 200mA, 2A, 20A Ohms 200n. 2kn, 20kn, 200kn, 2Mn. 20Mn Frequency 2kHzi' 20kHz. 200v.Hz Capacitance 2n , 20nF, 200nF. 2µf, 20µf $214.80 Modal 76 Camponont Teste r Does the things your multi meter doesn'tl • Capacitance 200pF to 20uf • Resistance 200n to 20Mn • Transistor hfe and lceo • Diode displays Vf at 1mA • LED disgIar5 Vf at 2Ma and 1Orn/ : ~~¼e~as~~1in:rd 1.5V cells $142.R0 Geoff Wood Electronics Pty Ltd (inc in N s W) 229 Burns Bay Road, (Corner Beatrice Street), Lane Cove West N SW sul'P 0 -9;,Mail Orders to - P O 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 ~ 1 0 Mail Orders add $5.00 min to cover postal charges 3 . ~ ~ Next day delivery in Sydney add $5.00 -1 \> If.... JJte C"tt:'1 All prices INCLUDE sales tax unless stated otherwise &srn~"' · , VOo E\..~ Tax Exemption Certificates accepted if the line value exceeds $10.00 -----~ BANKCARD, MASTERCARD. VISA, CHEQUES or CASH cheerfull v accepted. a 4'v~ ~ (o -"~ ~~-"'-:\ p ~ ~ 2 "6 p 8 c::, 23 :0 () ;i;; r 8 c::, ~ () ;i;; r 8 CJ 23 :0 () ;i;; ~ § CJ ~ () ;i;; r 8 CJ ~ ::0 () ;i;; r § ~ £ r ~ 23 ::0 £ r ~ ~ () ;i;; -0 p ~ AMATEUR RADIO BY GARRY CRATT, VK2YBX PEP monitor circuit for transmitters & transceivers Althoug~_most analog meters are capable of making accurate measurements of the constant power modes used in amateur stations, they're no good for measuring peak envelope power (PEP) ~The circuit presented here is designed to give accurate PEP readings. Because peak power equ ates to "talk" power when using SSB as a transmission mode, being able to measure this output power accurately is important to SSB operators on HF, VHF and UHF alike. The inability of a standard analog power meter to correctly measure peak power is largely due to the inertia of the meter movement used. By necessity, the movement must be damped to some degree to ensure that it cannot easily be physically damaged. This means that the meter is unable to track rapid transients. Not only that, the peak indicated power is only visible for a fraction of a second, making visual recognition difficult. Indeed, this is also the case to a certain degree with transmission monitors using a CRT, although they are quite useful in ensuring that the transmitted signal is not unduly distorted , a common problem when linear amplifiers are driven into compression. Such units also require a significant financial investment. What is needed then is some system where the rapi d modulation transients can be monitored and the metering system modified to lengthen the response time, so that they can be easily seen. Of course oommercial PEP meters do exist, as do retrofit circuits designed for specific units such as the "Bird" wattmeter series, recognised as an industry standard. Once again , the cost cannot be justified for amateur use. The circuit described here is similar to one that has been previously publish ed overseas but includes several improvements. In essence, it takes the fluctuating DC signal which would normally be fed to the existing meter movement, feeds it to a "sample and hold" circuit and then drives the meter. Circuit details Now refer to Fig.1. The circuit uses a DC coupled op amp (ICla) and a voltage fo llower (IClb) to drive the original meter movement. The output of the first op amp charges a lµF capacitor through a l00kQ resistor, setting the circuit rise time to lO0ms. A 4.7MQ bleed resistor ensures that the decay time is set to several seconds, enough time to read the peak value on the meter. In more detail, the DC input signal to the circuit is fed across VRl, a 5kQ potentiometer in series with a lkQ resistor. This network effectively replaces the original meter movement. + ,ooI.- ,oOk 100k INPUT + VR1 5k 1M 1k VR2 50k - 0.1 03 1N914 04 1N914 ~ 4.7M 1M ":' 84 SILICON CHIP - - - ---<11----<.1 OUTPUT TO METER .,. ,. Fig.1: this circuit is intended to replace a normal analog meter for reading peak envelope power. It is essentially a sample and hold circuit. Note that it has no RF detector circuit but is intended to be driven by the fluctuating DC across a normal moving coil meter. Fig.2: the PC board overlay diagram. The board is intended to be mounted inside a normal RF power meter, possibly with switching to give "normal" and "PEP" readings. At right is the full-size PC pattern. The input signal is then coupled via a lOOkQ resistor to pin 3, the non-inverting (+) input ofICla. IC1a acts as voltage follower and charges the lµF "hold" capacitor via diode Dl. Dl is connected inside the feedback loop for IC1a so that the circuit can respond to quite small signals. Op amp IC1b buffers the lµF capacitor (ie, places negligible load on it) and drives the external meter via diode DZ . Diode D3 protects the meter movement against overdrive. Since one side of the meter is connected to the 0V line and the other side is driven by IC1b via DZ, it follows that the output of IC la and IC1 b must be biased so that they are normally about +0.6V (ie, one diode drop) above 0V. This is accomplished by th e biasing network involving trimpot VR2 , the two 1MQ resistors and diode D4. Any op amp capable of operating from a single supply rail _a nd allowing the output to go to ground can be used. The LM324 or LM358 are suitable, although the 324, being a quad amplifier, is somewhat wasted in this application. The entire circuit can be run from a 9 volt battery, which in our circuit feeds a 5 volt zener regulator. As the total current drain is less than 2mA, this arrangement could last six months or so in continuous use without a battery change. Construction of the unit is simple, with the idea being to fit the PC board inside a standard wattmeter case, if possible. Fig.2 shows the parts placement on the PC board. You can install the parts in any order you wish but take care with component orientatfon. Calibration Calibration of the circuit is straightforward . Set both trimpots to their midpoints and connect the transmitter to the unmodified meter in the standard manner. Set the transmitter so that the meter reads half-scale. This can be done by adjusting the actual RF output power or, in some cases, decreasing the DC supply voltage. Having set the transmitter to read half-scale, and without making any further adjustments, disconnect the power meter, open it up, disconnect the two wires leading to the meter movement (taking note of the positive lead), and connect the new circuit board output to the meter movement. This done, connect the circuit board input to the wires previously removed from the meter movement. Now turn the transmitter on and adjust trimpot VR1 until the meter reads the same as it did prior to the addition of the new circuit board. Reassemble the meter and recheck. In some cases, input matching of the circuit board can be assisted by replacing the lkQ series resistor with a lkQ potentiometer. This should allow finer adjustment. To adjust VR2, turn off the transmitter and check the meter reading in this "no signal" condition. Adjust VR2 so that the meter reads zero. Now recheck the accuracy of the meter and readjust VR1 if necessary. 'If desired, the unit can be switched in or out by using a DPDT switch to bypass the circuit board. Alternatively, as the gain of the circuit is unity, the decay response time can be shortened by reducing the value of the 4. 7MQ resistor, by switching a 100kQ resistor across it, when in the "normal" mode. References National Semiconductor Linear Data Book 1; Radio Communications magazine (USA) January 1989; Ham Radio magazine, September 1989; ARRL Handbook. SC ~ PARTS LIST ! 1 PC board, 60 x 65mm, code SC06107911 1 LM358 dual FET-input op amp (IC1) 4 1N9 14, 1N4148 signal diodes (0 1-04) 1 5. 1V 400mW zener diode (2 D1) , 1 50kQ trimpot (VR2) 1 5kQ trim pot (VR 1) 1 ~ 1, 1 , Capacitors 1 1 1OOµF 16VW electrolytic ; 1 1µF metallised polyester or polycarbonate 2 0. 1µ F metallised polyester or ceramic 1 .00 1µF metallised polyester or ceramic 1 Resistors (0.25W, 5%) 1 4.7MQ 2 1MQ 3 100kQ 1 1kn 1 470Q I JULY 1991 85 Phone your order to us Toll Free. . We guarantee our Jetservice Courier will deliver ♦ to your door faster than any other Australian supplier (including that local supplier just up the ♦ road). If we fatl I'll give you your money b~ck ~ t1/ plus $5.00 for your inconvenience.~ 0 ~ Look At Thlsll Just Po11lbly the Ultimate Speaker · Driver True RMS AC Reading Analog/Dlgltal Multimeter IF YOU PUT A SOLDERING IRON AND A SOLDER SUCKER TOGETHER. WHAT DO YOU GET? The Altronlcs Multiple DeSoldering Tool This lightweight de-solderinQ iron allows components to be quickly and cleanly removed with one hand . Naturally it's SEC approved and comes with a cleaning wand. Can be used as a soldering iron . 240VAC 30W. Earthed . Simple cleaning action. These woofer/ midrange drivers have just arrived and are becoming all the rage , Built from exotic Japanese materials eg . 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T 24711 .0mm Spare tip• T 2472 2.4mm T 2473 3 .2mm ea T 2474 4.8mm T 2476 Blow torch T 2477 Hot ai r blower $13.95 • Altronlcs Serles II Aviation Headset Now you can have a quality multimeter that has just about everything at an affordable price. The quality design and high sampling rate make this multimeter incredibly accurate, ~ its~ ~~guh ~'llfe'lf~~ase means this meter 1 Features include - 38 ranges, temperature 1 Why pay $400 or more for a David Clarke set? measurement, capacitance check, transistor 8" CARBON FIBRE WOO FE R 60 WATTS RM S 100 W MAX. S 5305 A truly precision 90° displacement analog meter. Ideally suited to laboratory and the engineering test or design bench . Fully Portable Multi-Purpose-Gas Soldering Irons. A ready to use system, no instalation required! Completely self contained - No external siren or power supply required. Large coverage, over 100 sq . metres. Portable wall mounting. Long life 9V battery operation (not included) . Battery low warning. Recommended for home. shop. caravan or when travelling. tester. frequency counter, diode tester, continui:( check. and lar9e LCD displ'a;. ~=~i~~~/o meet I EC 34 class 11 and L 1244 SEE OUR 1991 CATALOGUE FOR FULL DETAILS a 1064 $149.oo Free Bonu, Temp(lrature Probe Th/1 Month Q 1067 ($30 Value/) Auto-Ranging Multimeter • Features include - Large LCD display. diode tester, continuity check, overload beeper indication, range annuniation. low battery indication and auto-ranging. Designed to meet IEC 348 Class II and UL 1244 standards. SEE OUR 1991 CATALOGUE FOR FULL DETAILS Fr•• Bonu, Carry Ca•• Th/1 Month a 1073 ($12.so Value/) a 1012 $89.oo •High performance, noise attenuating earphones •Noise cancelling microphone • Cushioned head pad • Super sturdy • Great performance • Superb, professional pilot's headset will last a lifetime with reasonable treatment • Includes standard aircraft jacks. 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Such as accessing alarm systems , electronic doors, ignition killers or just about anything that comes to mind. \ quantltle■ . 1000'1 NOW IN SERVICE IN UNIVERSITIES, COLLEGES, INDUSTRIES AND THE HOME WORK BENCH THROUGHOUT AUSTRALIA. Our superb version incorporates the latest refinements and is now housed in an attractive, tou~h "ABS" instrument case. This all new compact version has been made possible by use of a high efficiency toroid power transformer. So you win four ways less heat, less weight, greatly enhanced appearance and easier to build. GET AN AMAZING BASS IMPROVEMENT FROM YOUR STEREO SYSTEM. This fantastic adaptor simply "samples" your st6reo amp output and provides a single channel output to feed a separate sub~woofer amp. Unwanted audio spectrum is removed with the Frequency • Control (cut-off threshold adjustable 60130Hz) . Also includes an "out of phase" output enabling the use of stereo amp in a bridge configuration for those who really want to rattle the floorboards . 2515 ~.oo $249.oo K 1e2s $39.95 K 5560 $29.e5 Studio 200 Serles 100 Watts Per Channel Power Amplifier K I . ,. . -~ Fruit Machine WIN WIN WIN WARNING THIS KIT IS VERY ADDICTIVE. This novel kit works just like a real poker machine but without the expense of losing money. It has a jackpot and five other winning combinations. GREAT AT PARTY'S K 1160 $35.oo Ttie sound quality and overall specifications of this amplifier will compliment any sound system . The overall mechanical design and pre-drilled chassis means that this kit virtually falls together and should only take the average constructor about 6 hours to build. Why pay hundreds of dollars when you can build it yourself and end up with a quality professionally finished amplifier? FEATURES: In-Built speaker protection, To,oidal Transformer (Low Hum) , Black Satin Finish, Low leakage power supply capacitors, Housed in Rugged Custom Chassis. K 5010 $425.oo Studio 200 Stereo Control Unit The Studio 200 Stereo Control unit is companion to the studio 200 stereo power amplifier (and other power amps). It features slim 1u rack mount profile, treble ; stereo mono switch and volume control. Inputs include phone, tuner, V.C.R . & tape. Virtually all components mount on PCB's, making assembly and construction a breeeze. Altronics kit includes fully professionally punched and printed panels. Buy Both Kit For $599 and Save K 501s $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 virtually every other Australian supplier, we send goods at consignees risk. ~'",ould you require comprehensive insurance cover against loss or damage please add $1.00 per $100 of order value (minimum charge $1 ). When phone ordering please request " Insurance". 174 Roe St. PERTH W.A. 6000 Phone (09) 328 2199 TOLL FREE PHONE ORDER - Bankcard, Visa, Mastercard Holders can phone order PHONE ORDER TOLL FREE 008 999 007 toll free up to 6pm Eastern Standard Time. Remember with our Overnight JelMrvtce we MAIL ORDER C/ - P.O. Box 8350 Perth Stirling St. W.A. 6849 deliver next day. STANDARD DELIVERY & PACKING CHARGE $5 50 to 1 Kg, $8 1 Kg-5Kg AL TRON ICS RESELLERS- chances are there is an Altronic Reseller right AUSTRALIA WIDE - Via Australia Post allow approx 7 days for delivery near you - check this list or phone us for details of the nearest dealer. OVERNIGHT JETSERVICE Up to 3Kg Is $10 00, 3Kg to 5Kg Is $28 00 Overnight Blue Ribbon DHlera are highlighted with a ■ These dealers generally carry a Jeteervlce Courter for delivery next day Country areas please allow add1t1onal 24-48 comprehensive range of Altronic products and kits or we'll order any required item hours. for yo4. 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 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) 853 622 VIC. All Electronic Components (03) 6623506 The Electronic C.o mponent Shop ■ (03) 6706474 BORONIA Ray Cross Elec t ronics ■ (03) 7622422 CHELTENHAM Talking Electronics (03) 5842386 CROYDON Truscott Electronics ■ (03) 7233860 PRESTON Preston Electronics ■ (03) 4840191 ~OUNTRY BAIRNSDALE LH & LM Crawford (051) 525677 BALLARAT Ballarat Electronics (053) 311947 BENDIGO.KC Johnson ■ (054) 411411 MILDURA Mc William Electronics (050) 2364101Q LD, Delsound PL ■ (07) 8396155 NEWSTEAD ECQ Electronics (07) 2541153 WEST END B.A.S. Audiotronics (07) 8447566 WOODRIDGE David Hall Electronics ■ (07) 8082777 CO UNTRY MAROOCHYDORE MALS Electronics ■ (074) 436119 MARYBOROUGH• _ Keller Electronics (071) 214559 PIALBA Keller Electronics (071) 283749 ROCKHAMPTON Access Electronics (East St.) (079) 221058 TOWNSVILLE Super Solex ■ (077) 724466 SAForce Electronics ■ (08) 2125505 BRIGHTON Force Electronics ■ (08) 3770512 CHRISTIE& BEACH Force Electronics ■ (08) 3823366 ENFIELD Force Electronics ■ (08) 3496340 FINDON Force Electronics e (08) 3471188 LONSDALE Force Electronics ■ (08) 3260901 COU N T RY WHYALLA Eyre Electronics (086) 454764 TA$. HOBART George Harvey ■ (002) 342233 LAUNCESTON George Harvey ■ (003) 316533 NSW David Reid E lectronics ■ (02) 2671385 CITY SOUTH Sheridan Electronics (02) 2817727 SMITHFIELD Chantronics (02J° 6097218 COUNTRY COFFS HARBOUR Coffs HabourElectronics (066) 525684 NEWCASTLE Novocastrian Elect.Supplies(049) 621358 WARNERS BAYVilec Distributors (049) 489405 WINDSOR M &. E Elect. and Communications _(045) 775935 WOLLONGONG Newtek Electronics ■ (042) 271620 COMPUTER BITS BY JENNIFER BONNITCHA Windows on a brave new world Microsoft Windows 3.0 has meant a re-evaluation of the way we look at computers. And please all you Mac users, no wailing and gnashing of teeth. The new-found power of the graphical user interface (GUI) means that you, as a Windows user, need to look at your computer from the macro rather than micro aspect. Once all you had to worry about was whether you had sufficient disc space to run an application. The character-based DOS programs always ran as standalone programs with clumsy file transfers sending information to other programs. Windows has changed all that so that you can easily transfer information from one program to another without the need to "massage" it in the receiving program. Windows is almost infinitely customisable (is there really such a word?) and has a large array of add-on programs such as games (surprise, surprise), screen savers, icon makers and so forth. One of the program's tastes, and how to get the most from Windows and your computer. If you are considering the move to Windows, here are some points to think about. Software compatibility First, take stock of your computer and determine whether all the DOS programs you currently run are available in Windows versions. If not , you can certainly run a DOS application in Windows, and this will be discussed in a future article. Where possible , choose Windows applications that support the Dynamic Data Exchange (DDE) protocol. DDE permits separate applications to share the same data; eg, you could create a worksheet in Excel, with supbiggest features is that it allows in- porting graph, and have that graph house developers to customise appli- display in Windows Word. As you cations to suit their organisations. make changes to the worksheet, the While thinking about this series on · graph changes both in Excel and Windows Word. You need do nothing exWindows, the main problem has been where to start - an overview of the cept change the worksheet data! program, straight into installation, or But how much is it going to cost if general tips and tricks? Let's settle on you need to upgrade the version of a general overview first. In following your current program(s) to take admonths, we'll show you how to per- vantage of Windows. The effect on sonalise Windows to your needs and the hip pocket of such a major change To really run Windows, you need at least a 386SX system, an EGA monitor and 3-4Mb of RAM. 88 SILICON CHIP to your computing environment should not be underestimated. Hardware requirements The minimum hardware requirements for Windows 3.0 is an 8086 processor. That said, various industry tests indicate that in order to really run Windows you need at least a 386SX system, an EGA monitor and 3-4Mb of RAM. While Windows actually requires a minimum of 1Mb of RAM, many Windows applications (such as Ventura for Windows) require more than this. Windows' customisation features and its exploitation of the capabilities of the 286/386 processors all add up to a bright future . The original 8088 processor chip on the IBM PC doomed DOS to a 640K memory limit. The later series processor chips in the AT and 386-style computers can address memory in excess of the old base limit. The catch 22 is that the software has to be written to exact guidelines to take advantage of the extra memory. Make sure all your hardware is supported. Although Windows is shipped with a comprehensive range of drivers , if you have a mixed-vendor system, you may run into trouble. Although Windows 3 does not truly multitask, multiple programs can be run at the same time in separate windows. The transfer of information from one program to another can be accomplished in several ways, depending on the type of application you are running. Transfers can be via the clipboard, which may be saved as a file for later use, or through the "realtime" DDE links. Windows modes Windows' multitasking and cutcopy-paste capabilities vary depending on the mode that Windows is run- WIIIIIEl11i&FIIElliQ i-1 File Options Window Help • Accessories Non Windows . ~ ~ \;/rite Corel Draw PageMaker Corel Trace l;/FNBoss 41 II Scan File Manager g- ~ Control Panel I Print Manager lml!D DO~ Prompt Windows Setup DOS Exec ATM Control Panel Aldus Aldus Setup DD Main ~ Excel For your share of the prizes Paintbrush lications PageMaker 4.0 •ii ~ In the March and April issues of Silicon Chip we published the Notepad C,ardfile II CalcL,lator PIF Editor ~ Table Editor ♦ + ♦ ' You can customise Windows' program manager to suit your tastes & requirements. Among other things, you can change the icons, move the icons from one group to another, install new groups & change the screen colours. ning in. With Windows 3.0 you have the option to run in one of three modes depending .on your computer's hardware configuration: Real mode, Standard mode and 386 Enhanced mode. Real Mode: W.i ndows runs in this mode if your system is an 8086 or 8088 computer with at least 640K of conventional memory. You may find that Windows. will also run in real ·m ode if your computer is an 80286, 80386 or 80486 with less than 256K of extended memory. If you have any expanded memory, Windows can make use ofit- though this memory is not used in standard mode or 386 enhanced mode. Standard Mode: Windows runs in standard mode if your system is an 80286 computer (or higher) with at least 1Mb of memory (640K conventional and 256K extended memory). This is also the more realistic mode for running DOS applications. Although Windows and Windows ap plications can access all the memory installed on the computer (up to 16Mb), DOS applications are still restricted to 640K. Enhanced Mode: This is the optimum operating mode for Windows (depending on your hardware requirements of course). Enhanced mode calls for an 80386 computer (or higher) with at least 640K of conventional memory SENDINYOUR APPLICATION and 1024K of extended memory. You can run DOS applications in this mode, together with a disc-based virtual memory manager and background processing. Many programs are designed to run in Standard rather than Enhanced mode. If you think a program is not running as fast as it should, try running Windows in Standard mode. You can start Windows using one of three switches to select the required mode, although more about this later. Weigh up the cost benefits of Windows for your computer or organisation. Any upgrade or change is expensive so the move from DOS to Windows involves not just dollars but also time spent adjusting to the mouse and new menus. One of the interesting features of all mouse-driven programs is that while you can certainly key ahead if you know the correct keyboard sequence, it is much more difficult to "mouseahead". While you can execute a command with the mouse and have it poised at the next screen location, you really can't set up a string of commands (unless you write macros, etc). This adds up to a fair amount of wasted time, sitting and staring at the hour-glass on the screen. Next month, we 'll talk about installing and customising Windows. SC Remote Controller for Garage Doors. The feedback from this project has been enormous. You · have to send in your application of how else this kit can be used. Plus a couple of photos if you actually put the application into practice. In conjunction with Oatley Electronics this is your opportunity to share your application and possibly pick up a prize as well. Even if you have not built the Garage Remote you can still send in an entry. Entries close on the 30th of August 1991, arid will be judged by the technical staff at Silicon Chip. What you could win? 1st Prize. 7mW HE-NE Laser and Inverter. All you need to power this unit is 12-14VDC. This is a red Laser and is valued at: $580.00 2nd Prize. Infra Red Night Viewer.See in the dark with this great night viewer. In this kit you will get a NEW 6032 Image converter tube, Case and the components kit. This prize is valued at: $339.00 3rd Prize. lmW Laser head with a commercial inverter. All you need is a 12V supply. This prize is valued at: $309.00 Plus 10 Ultrasonic movement alarm kits valued at $50.00 ea. SEND ENTRIES TO: GARAGE DOOR COMPETITION P.O. BOX 139 COLLAROY BEACH NSW 2097 JULY 1991 89 REMOTE CONTROL BY BOB YOUNG The development of digital proportional RC transmitters As we have noted in recent columns on this historical series, the development of the proportional control transmitter was a long, slow process which had its roots in the Galloping Ghost and similar analog systems. Galloping Ghost transmitt ers had only one stick, which gave rudd er and eleva tor control, and a lev er switch which gave positionable throttle via a pulse omission detector in th e decoder. This was quite primitive, as noted in previous articles on the Galloping Ghost system. Even more primitive by modern standards was the construction of the control stick assembly which was a very popular and reliable unit made commercially in the USA by "Protrol". The direct mounted potentiometers and the large completely open square hole is a far cry from the modern sealed gimbal in today's sets such as the Futaba Tx featured in this article. However, this type of stick construction died hard because it had one great advantage over the modern sealed gimbal: the excellent centring accuracy obtainable from th e direct mounted pots. The ·Americans fought hard to retain this typ e of stick assembly and retained it on their top-line competition sets almost until they were forced out of the commercial market. The customer is right The Japanese eventually got a stranglehold on the R/C transmitter market by producing sets with sealed gimbals, all moulded plastic contruction and lots of operating features. 90 SILICON CHIP Here we see a very practical and technically superior device giving way to customer pressure, for some very valid reasons secondary to performance. The "open gimbal", as it was known , was prone to dust ingress into the electronics and the large hole was quite ugly when compared to the slick finish of the modern Japanese units moulded in full plastic. The coup-de-grace was delivered to the open gimbal as the accuracy of manufacture of the sealed gimbal gradually improved. Today's sealed /, The interior of this Silvertone transmitter (made around 1969) shows a board using a half-shot encoder. The folded metal construction, while desirable from a technical point of view, was far less attractive to modellers than the modern moulded plastic sets. gimbals give nearly equal results and offer the above advantages as well. Thus died the "open gimbal" transmitter. It is interesting to note the rigid thinking of the American R/C manufacturing industry. Quite apart from the price disadvantage, they failed to recognise the importance of packaging and styling and thus they clung to the traditional methods for far too long. Their greatest failings were in staying with folded aluminium transmitter cases and in not recogmsmg the need for improved servo g\)artrains. That said, there were sound technical reasons for retaining the aluminium Tx case, even if it did look old fashioned, but their failure to improve their servo geartrains is totally inexplicable. As the Americans were the only reliable suppliers of OEM parts for small manufacturers, I can remember pleading with them, year after year, for more powerful and quieter geartrains and moulded transmitter cases. The pleas fell on deaf ears and my own sales suffered along with the Americans. In desperation and despite the cost, I finally began tooling for my own servo cases, but by this time the battle was lost. Thus died a major component of the Australian R/C industry. However, once again I digress and we must return to the main story. From the Galloping Ghost systems there developed full house analog proportional sets which featured two twin axis gimbal assemblies and looked for all the world like a typical early model digital system. The only problem was that they did not work anywhere near as well. Thus, we can see that by the early 1960s the mechanical form of the proportional transmitter was well established. Mathers & Spreng When Mathers and Spreng dev eloped their digital system in the early 1960s, there existed a sound mechanical layout to install their electronics into and there was nothing here to excite the fans. However, the revolutionary aspect of the Mathers and Spreng concept was in their use of the then almost unheard of digital techniques. In this , they turned the world of R/C electronics completely on its ear. Within a decade, their system had become the industry standard and completely swept aside all other systems. We have already examined th e digital servo and noted its need for a positive input pulse whose width is variable from 1-2ms. Spreng and Mathers pion eered the use of what was then called PDM (Pulse Duration Modulation) which was not quit e technically correct and which has since given way to the more correct PPM (Pulse Position Modulation). The actual servo input pulse varies in duration it is true, however the modulation system they used converted pulse duration into pulse position and it was this feature that gave the transmitt er its most powerful advantage. In essence, what they did was to transmit the control pulses in a serial form using marker pips at the start and finish of each pulse (s ee Fig.1 ). The marker for the trailing edge of pulse number 1 was the marker for the leading edge of pulse number 2 and so on. Thus , the data was carried in the position of the marker pulses. This had several advantages over prev'ious systems in that th e system was virtually a full carrier system with only a narrow spike of no transmission. This kept the receiver AGC clamped into low sensitivity and thus the best state for noise rejection. The frame or repetition rate was also very fast with all eight channels being updated every 22 milliseco nds, ]ULY1991 91 MASTER CLOCK ._____ _J I CHANNEL 1 ____.I CHANNEL 2 . _ _ _ _ I_ CHANNELJ _ _ __ _ _ _ __.n------------~' I ....,I CHANNEL 4 _ _ _ _ _ _ _ _ MARKER PULSE TR AIN 0 ~ ti1 i~~~fb~ --++--+]+----++-+[]+-----(.._____.-++--) (......________.--) [ Fig.1: the Spreng & Mathers technique transmitted the control pulses in a serial form using marker pips at the start and finish of each pulse. The marker for the trailing edge of pulse number 1 was the marker for the leading edge of pulse number 2 and so on. spent in range checking, tuning and chasing fly-away models. You never went to the flying field without your name and address inscribed indelibly on your model. How long is it since anyone has done that? I haven't seen a name on a model for years. How times have changed. After the advent of crystal-locked superhets and digital proportional systems , we had nothing to do all day but fly the models and drink coffee; really boring stuff. We all very quickly began to put on weight from lack of exercise and I have not lost it since. Who said progress was all good? I can so there was no time lag in control response . In addition, the system was inherently stable, using as it did full monostable multi vibrators as the master clock and pulse-width generators. There was absolutely no tuning requ ired in the entire system. This fact absolutely floored us old timers, brought up as we were on tu ni ng direct coupled super-regen trans istorised rece ivers, tuned reed aud io tones and free running transmitter oscillators. Tuning and tweaking was an important part of life on the flying fi eld for us and a good part of the day was MARKER PULSE GENERATOR BUS VR1 50k TO ~ - - FOLLOWING CHANNELS _rL_ ..,. 92 S ILICON CHIP Fig.2: this simple "half-shot" circuit formed the backbone of transmitter encoders for many years. Any number of these circuits could be strung in a row, depending on the number of channels needed. remember once running after a model from the Cooks River up into the main street of Earl wood shopping centre, a distanc e of 3-4km. R/C modellers had to be fit in thos e days. They also had to be insensitive to the "village idiot" label inevitably hung upon them. Believe me, nothing looks sillier than a grown man chasing a runaway model whilst waving a transmitter aerial ineffectually at it. You also had to have a heart as big as a lion to walk into a house with a model sticking out of a broken. win dow or the tile roof and for ask it back. However I digress yet again, so back to the story. In 1964, Howard Bonner brought out the Digimite 8-channel proportional system which was very professional in approach and appearance. Featuring such novel features as failsafe and full y wired servos with plugs for instant interchangeability, this system set the pace for several years. The most remarkable feature was, however, the sea led control gimbals, a first for the industry. The Bonner system suffered several drawbacks as we have already seen in past articles, and the main criticism of the Bonner sealed sticks was the mechanical trim. Modern gimbals use a trim lever which rotates the body of the control potentiometer and thus gives about 15% additional range to the stick travel, leaving the stick still mechanically centred. Bonner, on the other hand, used a mechanical trim which again gave about 15% of the travel for trim but instead shifted the control pot by shifting th e mechanical neutral position of the control stick. The disadvantage of this system was that if the model was flying in a trim that required (say) full up trim, then the available up elevator travel was less than the down elevator travel. I personally felt this criticism was unjustified for the simple reason that a good fly er trimmed his model correctly so that the trim is always in the qmtre. This applies even today with the modern microprocessor encoders and I have stated this previously, on many occasions. There was one very big advantage in the Bonner sticks and that was that all of the servo travel was available from the stick regardless of the trim position, whereas in the electrical trim system, 15% of the servo travel is These photographs show the open gimbal construction used in Galloping Ghost transmitters. kept in reserve and not available from the stick. The microprocessor systems at least have cured this problem. This advantage to me completely outweighed the disadvantage of the stick centre moving and I used Bonner Screws ,... ·r•g . -. +l Fig.3: this exploded view shows the main components inside a modern sealed gimbal assembly. Note the yokes which operate the two pots & also the mechanical trim levers. <at>) No.2 xl/8" L- -<at>- Transmitter encoders To finish the discussion on transmitter development, we need to talk about transmitter encoders which were also partly covered in the January 1990 article. Although the full 2-transistor multivibrator used for producing PPM signals was very stable, it was also very heavy on component cost and the relent- No.2x5/16" l sticks in my own equipment for many years. I also continued to fly with these sticks long after I had changed my production sets to electric trim due to customer pressure. ~7ifflj1 f No.2x3/16" •lli.! . Side plate centring tab on other side 11(3 .2x1/8" Side plate/ ,,,,;,, ,/. I ' I J\ Allen key 1·5 mm Pot carrier keys Yoke ~Yoke,.,:,,.;• 4/40x1/8" Set screw ' "---, / Allen Bradley type J Threaded bushing Fig. 3 less pressure for cost savings produced the clever little circuit featured in Fig.2 . Known as the "half-shot", it very quickly also became industry standard and was the backbone of transmitter encoders for many years. You just simply strung as many of these things in a row as you needed channels. and you had a simple and very reliable transmitter encoder. We built 32-channel transmitters for our robotic puppets from these pulse width generators and they were very successful. Their big asset was their voltage stability while thir chief disadvantage was again component count when compared to the new IC encoders. Another disadvantage was that they were not flexible enough for modern demands in regard to servo reversing, dual rate and exponential control configurations. Thus they gave way to the balanced rail encoders which used a stable reference voltage and which allowed symmetrical operation for servo reversing at the transmitter end. The Signetics NE5044 is good example of this type of encoder. However, nothing beats the microprocessor for flexibility and they are gradually finding their way into more and more R/C transmitter encoders. Finally, while this electronic race for improvement was in progress, there was a relentless quest for improved appearence and accuracy in the transmitter mechanicals. The transmitter of today, loaded to the gills with microprocessors and liquid crystal displays, is a far cry from the bent tin jobs that us old timers called the answers to our prayers. SC ]UL Y 1991 93 Australia has the largest and most complex water management and hyroelectricity generating system in the world - the Snowy Mountains Hydro Electric Scheme. Built over a 25-year period, it now provides great benefits to the people of NSW & Victoria. By BRYAN MAHER The story of elechical energy, Pt.11 J\ USTRALIA is the world's driest £'l.. continent. Finding reliable supplies of water is more ,important then even the discovery of gold. The western farmers of Victoria and NSW once suffered agonising droughts while fresh water from the Snowy Mountains was wasted, flowing eastward to the sea. The Snowy Mountains Hydro Electric Scheme was designed to alleviate the effects of both flooding and drought and provide electric power at the same time. Seven power stations, including two underground, together generate more power than the largest thermal power station in Australia. The whole 94 SILICON CHIP undertaking is the largest, most complex water management-electricity generation structure in the world. Hydroelectric proposals The catastrophic 1880 drought wrought such havoc that urgent proposals arose to divert water from the Snowy Mountains to the west. By 1908, further examination had produced a threefold proposition: (1) . Diversion of Snowy River waters to the west. (2). Dams to be built to ease both drought and flood conditions. (3). Hydro-electricity generation to supply the proposed national capital. Proposals came aplenty, but the first viable dual large-scale plan came forth in 1947. A joint State-Commonwealth technical committee investigated the whole question and NSW ceded to the Commonwealth the rights for the water to be used as a power source for the ACT. Above: while electricity generation is a key element in the Snowy scheme, less well known is the important part it plays in flood mitigation. Here the sluice gates on the Jindabyne Dam are wide open during late 1974 as they release part of the previous winter's snowmelt. &LOWERING RESERVOIR TOO MA RESERVOIR ,..s..,oo-=-o'-=FE=-cET_ _ _ _ _ _ _ _ _...,JOUNAMA PONOAGE l OGILVIES INTAKE OUTSTATION DEEP CREEK INTAKE p4,,_,00"'-0-----~&LOWERING --i---tTUMUT 3 POWER POWER STATION STATION 3000 2000 TO MURRUMBIDGEE IRRIGATION A R E A - - - - - -- ------ - - TUMUT 1 TUMUT HAPPY JACKS POWER POND PONDAGE --STATION--RESERVOIR - - - - - - - - - - - - - - - - - - ~ Snowy-Tumut Development 70""'0-"-0F'-"E"-ET_ r'- __,KH~~~g:~N MURRAY MURRAY 1 OGONG GEEHI --------.-GILTHEGA - - - - , ISLAND BENO JINOABYNE - - - - - - - , L A K E - - - ~ 2 POWER POWER CREEK RESERVOIR PONOAGE PONOAGE PUMPING EUCUMBENE STATION STATION INTAKE BURRUNGUBUGGE STATION 6000 i=="-----+---+---+---+-----+-----+----..C...,,-T""""-+-------i---------.n,TAKE LAKE JINOABYNE---+---------1 5000 4000 3000 TQ.MlJRRAY GUTHEGA POWER 0 IRRIGATION AREA - - - - - ' - ' = = = - - - - - - - - - - - - - - - - - - " S - " ' T A " ' T l " ' O N ' - - - - - □ ~:1"~~ ~~~~~r 6 0 0 ~~l~ :T~¥~ N ...JL TUNNELS ANO SHAFTS Snowy-Murray Development Some idea of the broad scope of the Snowy Mountains Hydro scheme can be gained from this diagram which shows every dam and power station and pumping station involved. Many tunnels and shafts are also involved, to transfer water to and from reservoirs. In 1949, The Commonwealth Government established the Snowy Mountains Hydroelectric Authority (the SMA). It was given responsibility to investigate, design and build the scheme. All earlier proposals were considered, some proposing as much as 800km of open channel aqueducts. Previous schemes proposed 16 power stations generating a total of 2.6 gigawatts. When one takes a 3-dimensional view of the Snowy Mountains, it is difficult to comprehend the complexity of the final plan, let alone the finished construction. The Authority's final design envisaged 144km of tunnels, 80km of aqueducts, 16 large dams, 7 power stations generating 3.74GW, and many smaller projects. Included under the heading of "smaller projects" were: (1). Shifting a whole town, including the removal and rebuilding of the historic stone church at Adaminaby; (2). Establishment of seven regional towns and 100 camps; (3). Building over 1600km of roads, access tracks and rail lines; (4). Construction of hundreds of kilometres of high voltage power lines (10 at 330kV and four at 132kV); (5). The transport of bulky, heavy power station equipment from seaport to site; and (6). Supervising the many subcontractors and caring for the 100,000 people who worked on the scheme at various stages. The first blasting shot was fired in 1949, and the whole scheme was completed on time, on budget, by 1974. The cost was $820 million. The highest number of on-site employees was reached during 1959, when 7300 people toiled on the project. Cash loans from the Commonwealth paid for the work. Thes e loans are being repaid over 70 years from sales of electricity. No charge is made for water used by the states for irrigation purposes. Large scale engineering The Snowy Mountains Scheme still ranks as the greatest and most complex water management/electri city generation undertaking in the world. The project was built over 3200 square kilometres of immensely difficult mountain terrain and is truly the greatest engineering feat yet accomplished in Australia. One dam alone holds nine times the volume of Sydney Harbour. The water management aspect involves a complex system of dams , tunnels , gates, valves and pumped storage. The geography naturally divides the scheme into two sections: (1). The northern Snowy-Tumut development; and (2). The southern Snowy-Murray proj ect. This follo ws from the three-cornered layout nature originally created. The Snowy River runs roughly from Mt Kosciusko to the south east. The Ge ehi flows south w est from the mountain to pour into the Murray. The Tumut River (originally called Doomut) crashes down its precipitous gorges in a north westerly direction to join the Murrumbidgee near Gundagai. Central to both sections of the scheme is the Eucumbene Dam. This , by far the largest storage in the system, holds 4. 798 billion cubic metres of water. Completed in 1958 , its rockcapped earthfill wall rises 116 metres above th e bed of the Eucumbene River. As is usual with earth/ rock dams, the ]ULY 1991 95 ~~ ~; _ &/ 1 . "#'., l!lfl\ T 01 ,✓ • "); ;- ·- ~~ ~ ,:~~~ ~ ';{e]IIIU'ilHIH=Wi❖UIUst·liMii·WK•maot--.--~--, :/ .~ r , ""· ~ I • • -:, •. • .- fr\\ l-......,·/ . '• \ ~ -. Cl. .\ ::J 'I!. > .,.,~ Q , '<c, ~ ~~ l11 ~, z • . ®. 19 ,o 99 100. ~ '- · <♦• ~ UJ G a:: ,)..._...,. 1 Q ( • ,. I- (/) 19 .... ~ ., _ - 1). {l BNC . SOLDERLESS TWIST ON PLUG Q a:; < ~ :E > cc ~ ~ UJ 3: CANNON TYPE 3 PIN CHASSIS MALE to. 100 , 1.g P10ll62 $3.50 $295 $250 J l:•w r CA~ TYPt ·i.· 1-9 10. -' 3 _jj j ~ LI.. ~ M ,... L 19990 .. .$2.95 Receive, Ll 9991 .. $ 2 .9 5 $1 .95 Range : 300 feel in open field RECIEVER SPECS , P1°"66 $4.95 $4.50 $3.50 1-9 10 , 100+ P10860 $4.50 $3.50 $2.50 COMPUTER CABLES i CI) -~ · S11 condu clo computer m · m : mel re W1267 1.9 m $1.30 W1 . m •·• $1 I OO+m $1.90m 100. m $2.50m · CIC25 100. m 3.40m $3.00m 1-9 $l.95 10+ LESS PHOl~E 1:, red5mm 210159 1-9 $1.10 10+ $1.00 ==II 1.40 : ;~ 1.80 2.75 2.70 3.50 3.50 4.50 1-0 10-99 100+ RED GREEN 10 100 YELLOW ORANGE Watts ONLY ..... .. .. .. ..$9.95 $9.95 t - - - - - :=P =R ==1'="' cE 01-1s\\\ $1.50 $1.20 $1.00 20c 20c 20c 20c 12c 12c 12c 12c 15c 15c 15c 15c 0 10500 01050 2 010502 010533 0105'.38 010540 010550 010560 MU4 5 0•1mA MU4S 50..'SOu A MU45 0- 10().J A MU5 2 E 0 -SA MUGS 0-S0uA MUGS 0•lm A MU6 50- 100u A MU650-20V $9 .95 $9 .95 $9.95 $12 .95 $12 .95 $12.9 5 $12.95 $12.95 g pin 1ocket , .9 ,o. 100 · Pl2167 $1.50 $1.20 $1.00 15 pin M>Cltet . QA155 P.12169$1 .50 $1.20 $1.00 ~ -- IOC CEN.TRONICS 36 WA Y PL UG & SOCKET ,, S3 95 SJ 00 S2.95 · S0 r: ket 2SJ49 2SJ56 2SK 134 2S K17 6 1·9 10, $7.50 $10 .00 S6. 90 S9.50 $7.00 S9.50 S6.50 $8.90 80 • 80 • 25 4mm 12V DC 1 7 Wan 0 14 Am p s T1 2469 .. . . . ······ $12.95 10+ fans only $11 .95 each FANS Oual 1l y. lans !or use 1n po we r INSERTS 1w,11, µ,.,., 10, i,as v ooarri ,n~,.,., ,, r a1 (1r1 1•n ' .. $1 .20 VOLTAGE REGULATORS BARGAINS 12V DC FANS •o. 10c . $3.95 $3 00 $2.95 ELECTRET MIC 1 2 A H $9.95 $9.50 $8 .95 o 1 2 AH '9.95 $9.50 $8.95 amps, c omputers . hotspo t coo li ng etc An ywhere you need plenly or air 240V 4 5 8" T12461 $12.95 nsv 45 a·· T12463 $12.95 240 V J , 2" 115V J 1 2" T12465 $12.95 T12467 $12.95 5 1 / 4" • SOOK unformatted, • IBM• XP compatible C11901 ............. $175 MOSFET SPECIALS P1?171 $4 .50 $195 $3.50. · Plu g C 1.6 M!Byte unformatted • IBM• XP compatible C11906 ........... .$150 25 pin 1od.11t . D8 255 :~~ha~!~~• ' 1·9 10. 100. •• 450mAH $1.95 $1.75 s1 .so 5 1 / 4" 1 . 2 M/BYTE JAPANESE DRIVE 008 335757 ECONOMY TRANSFORMERS 1-9 TYPE IOC SOCKETS Save a fortune on expensive throw away batteries with these quality Nicads and We have a great range of panel meters at great prices! MAIL ORDER HORINE 2155 240V 6-15V 1A Cat M12155 $8.95 $7.95 2 156 240V 6-15V A2 Cal M12156 ' $13 .95 $12.95 2851 240V 12-6V CT 250mA CatM12El51 $4.95 $4.50 6672 240V 15 30vc 1A tapped Cat M16672 $12 .95 $11 .95 20 ,""'.~--.-..,-~---I ~-_- lw..Ji&i ~ LIil'~ PANEL METERS GALORE 100 . · D82SP 25 pin plug P, 11 10 $4.SO $3.95 $3.50 D 1---r .- $1.l0 s, . QUALITY JAPANESE ORIVES -4) lOWH O RN SPEAKER S ~ 11 l,;HES ;. 9 10- 99 Sll0 l 0S .PD.T$1.20 DPDT $l .30 51 10 20 Sensitivity : 100d8 0 .5 m Frequency respon se : JkHz•J·0kHz Independence : 8 o hms. Si ze 96 m d iameter Normally ........ ...... ..... $1 2.95 . DA 1SP 15 pin plug · DE9S TOGGLt:.::; NICAD::; • OE9P 9 pin plug • .,, .. $1.50 $1.20 $1.00 P'1 >68 , "' DS 0 JYPE IDC PLUGS 10 . · _i.__ --FLA~ Requ ires no cro:;sover and handles up $0.50 ' TOLL FREE MAIL ORDER HOTLINE 00833 5757 12 S0.12 ---- SUPER H RN TWEETER 1lf ,.9 j ~00,; LEDS )g:~ \ $1.50 $1.00 $0.75 Y11025 4.75 Mhz $1 .50 $1.00 $0. 75 Y11033 5.0688 MHz $1.00 $0.75 $0.50 Y11045 6.667 MHz $1.00 $0 .75 $0.50 Y11 0 61 10.6445 MHz $1.00 $0.75 $0 .50 Y11082 18MHz $1.00 $0.75 $0.50 Y11100 27Mhz $1 .00 $0.75 $0.50 Y11105 32MHz $1.00 $0.75 $0.50 Y11110 36 MHz $0.75 15 2 ~0152 (Y) $D.20 50 _15 ~ 8 Pin 1.50 85 95 18 Pin 1.95 20Pln 2.95 22 Pi n 2.95 3.95 3.95 4.95 1 -9 10-99 100+ Y11 0 07 2.304 MHz $2.00 $1 .50 $1 .00 · Y11009 2.7648 MHz $2.00 $1 .50 $1.00 Y11018 3 .93216 MHz $1.00 = $1 .00 $0.70 P10902 DB25C $1 .00 $0.80 QUALITY 5MM LEDS p 10904 0B25P $1.00 $0.80 Zt0150(R)s~~• P10905 0B25S $1.00 $0.80 S0. 1-----------1 210151 IG)so.20 S0. Output level , 37mV(max) , wire wrap sockets are ~ 100 + $1.00 $0.70 $1.00 $0.90 $1.00 $0.80 A bronze. ~ 10- P10895 DA15S $0.12 $0 .15 $0 .12 RECTANGULAR P1()g64 $3.95 $3.50 $2.90 1-9 P10891 DA15S P10B92 DA 1 SC Recei ver freq : 37.1MHz Wow! from $1.00 CANNON TYPE 3 PIN CHASSIS FEMALE Z10143(Y) ....$0.20 $0.15 $0.12 Z10145(O) ... $0 .20 WIRE WRAP 100 + PIN LINE MALE Ul 10+ Tc:•ynssla~i01! inc~la•,~ s~~m : 5 0 Mic,ophone , Elect,et condense, Powe, suppty,9V batte,y PIN LINE FEMALE LI.. zw ·Transmitter 1-9 $: :~ >6t :rr:;m, f OUALITY1! M~~ E~~ R .... So.,s $Q_12 so.,o O $~~ Pl0880 OE9P Pi0885 DE9S 25< 3 ~ - -11 CA;:pN IYPt:J .... . ' w w cc ..._/ t<1a . V'J ;;~;~~!tting Frequency : 22< Rei:~::1:~,;~• Supe, cr;,,ai 30< 25< Powe, sup, 9V batte,y 30< 26< Volumecontrol : TuningLed JOr 26< Di mmens ion s: 115x32 x44mm 35< 30< 1----------~ Weigh1 : 220grams 40< 35< 10452 ............... $99 heard so are ideal tor TV remote control's , water level detectors , 1099 100 · ,, tin -plated phosphor ...I / recieve at 40 kHz (L 19991)with up to 20V IIP on the transmitter. These units can·t be .Y 1•9 Designed to transmit at 40kHz (L 19990) and ,,.. 12< 10< 15< information carriers as lhey can be ei ther pu lsed or used in a co ntinues wave mode. .... ~ \..::_: ~ · .... l ll •i i t)J J: ~ ~ (ri'fiS: J: O . · 8 pin ...... 15t 14 pin 20< 16 pin . ... 20, 18 pin . JO• 20 pin .. .. 35t 22 pin .. 35e 24 pin . 35< 28 pi n .... 45t 40 pin . 45< Cl) .-· 1/ a: :~:':j -------- UL T ASONIC TRANOUCERS •·• P10550 P10560 P10565 P10567 P10568 P10569 P10570 P10572 P10575 IC SOCKETS These quality J level W ~ • Cal. No . Descripl,on OB25 CONNECTOR . SPECIALS ----,--., z~o~:~~G~ .... $0.20 $0.25 MICAOPHONESPECS : burglar alarms. motion detectors and J Illa: fl ' ! SOCKETS Save a small l onune on these " Direct Import" low ptotlle le socltels! PCB mounling solder tail . All ti n plated phosphor bronze or berrylltum and dual wi pe lor reliability. P1osJ1 $2.50 u .2, ,2.00 ~ / , ii: ~ the dt?vice lo the -=i& ---,I- z ~~;~:;:/::!,'~;~nsler tram ~= ~ ===1~ ===UIP; Ml~~~':v~~E & LOW PROFILE IC C <I: ~J:--', o ;J\ · I- r ,o 99 , • • , 0 • •,s•v<· 0530 2 0 5 2 7 2 00 1 - '- 100 1 P /r · O 1-Z II ma intains a pos illve eN,ciency. H11800 ..10g ... ..$2.00 H11810 .. lSQlL... $14.95 BNC CRIMP PLUG a:; ::, ,...-...-J O , • P10516. ..' .50 2 S2.25 $1.50 · ) [ r:~~~~n~n> heatsink . thus increa s1"9 overall BNC PAN SOCKETtL a. i\,• ~::~~~~:~un~•;,~des ~z c-=-! "i ( Ck YSTAL LOCKED WIRELESS ~ IQ00(1 applied to the base and Pt 0514 $2.50 $2.25 $1.50 ~.,,,,. ' S:2 •O I (/)3 ~ '\ BNC MALE PLUG • W '4,.~ 1r_r..,~· , ) -.,,n,,....,.....,.,.,.. HEATSINK COMPOUND Heats,nkcompoundis .;a : Description 7805UC 7812UC 7815UC 7905UC 7912UC 7915UC 78L05 78L12 LM324 555 741 1-9 $0.50 $0.50 $0.50 $0.60 $0.60 $0.60 $0.40 $0.40 $1.00 $0.40 $0.50 10+ $0.45 $0.45 $0.45 $0.55 $0.55 $0.55 $0.30 $0,30 $0.90 $0.38 $0.45 3 1 / 2" 1 .44 M/BYTE DRIVE , S\vitchable 1.44 M/Byte formatted or 720K formatted. • Double sided, double density • Power supply adaptor provided • 5 1/4" mounted C11911 without bracket. $149 with bracket ...... .. $169 Controlier Card to s X18009 ................ $1 APPLE* IIC compatible . 25 on1y1 DISK DRIVE; - Including cable r~ "."'" - ,r ½.. , r~-< •, ~ e. ~~ -;;.t j't-1 ·~ ---: ~ ---- ~ f:- ~ ~ . ~''" C1060 Equiv. Tag X04030E ...... $1.50 c1220 .......... $2.50 C122E ... ....... $ 1.95 2N2646 ........ $1.95 2N6027 .. . ... $ 1.20 IUtidil!tl Desc ription ........$ 2N918 .. ... $1.00 2N2219 .... .... $0.90 .... .... $1.00 2N2369 2N2646 ........ sa5 2N2904 ........ $1 .10 2N3019 ....... . $1 .90 2N3055 ....... . $2 .00 2N3563 ........ $0.35 2N3564 ........ $0.30 2N3566 ........ $0.30 2N3569 . ..... $0.30 2N3838 ........ $0.30 2N3641 ........ $0.30 2N3642 ....... . $0.30 2N3643 ........ $0.30 2N3644 ....... . $0 .30 2N3645 ........ $0 .30 2N3771 ........ $6 .96 2N3772 ....... . $5 .70 2N3773 ...... .. $7 .95 2N3819 ....... . $1 .50 2N3866 ... ..... $2 .95 2N3904 .... , ... $1.00 2N3906 ........ $1.00 2N4033 ..... ... $2 .20 2N4258 ........ $0.40 2N4356 ........ $0.50 2N4360 ···· ···· $1.50 2N4342 .. . ... $1.50 2N4401 .... .... $0.30 2N4427 ........ $3.90 ,/ --- <at> ' 2N5484 .. ... $ 1.50 2N50jl8 ........ $1.00 2N5089 ....... . $1 .00 2N5401 . ....... $0 .35 2N5458 .. $0 .90 2N5459 ........ $1 .00 2N5485 ... ..... $1.15 2N5486 ........ $1 .30 2N6027 ... . ·· • $1 .20 2N6125 ····· -· $1 .90 2S0350 ........ $6 .95 2SJ49 .......... $9 .95 2SJ56 .. ...... $14 .50 25Kl34 .... .... $9 .95 2S K176 ... ... $14 .50 1=~11a Desc npt1 on .$ W02 200V .. $0 .80 W04 400V .... $0 .80 U!,!f ./ I, s 1 10 .... ... . 1. SC141E ......... $1 .95 SC142E or Teccor S4008L Trlac .$2.25 SC1460 ........ $2 .85 SC1510 . ...... $2 .95 C 103B or MCA 100-6 ..... $0.90 KBP C604 400V ..... $2 .50 _) >· K8PC607 1ooov .. ...... .... s2 .15 J.ll.AMf KBPC,004 400V. ............ $3.50 KBPC1007 1ooov.. ...... .... $4.so 2U.ME K8PC2504 400V ............. $6 .50 KBPC2510 1ooov.. .......... s1 .3s \ ) !,>· ll.A!,1£ ,.•• $ 1N4002 200V. $0 . 10 1N4004 400V .$0 . 10 Description . 1 N40071ooov .S0.20 1AMf. Descrip tio n . 1 N5401 SOV .. $0.40 1 N5404 400V $0 .40 1 N54081 OOOV$0 .65 G ER MAN IUM DIODE KBPC3504 Description . .. .. .$ 400V. ..... ....... $6 .50 OA47 .... ........ $1 .50 KBPC3506 OA90. ..... ..... $0.40 600V.... ..... $6 .75 OA91 . ........ $0 .75 KBPC3510 OA95 ............ $0 .75 1000V.. .. ....... $8 .40 ",,,,✓• ~. '4,,, ~¼:; , .... ' -- 8C549 .........$0. 15 8C550 ... ..... $0.:30 8C556 .... ...... $0.:30 8C557 ... ... $0.15 8C558 ... ....... $0.15 8C559 .......... $0. 15 8C639 .......... $0.80 8C640 ... ..... $0.80 8 01 39 .......... $0.90 8 0 140 ··········'°·90 8 0 237 .......... $0 .90 ... $0.90 B0238 .. 8 0650 ... ...... $1.95 8 0 649 ... .... $1.65 80647 ........... $1.80 .... $2.00 80681 8 0682 ........... $2 .00 8F115 ........... $1.00 ... $1.20 8F1 80 .. BF199 ........... $0.60 BF245A ... $1.95 8F469 ........... $1.20 8F470 .. ..... $1 .20 8FY50 ...... ..... $1 .50 8FY90 ........... $3.00 8U208A ...... .. $4 .90 8U326A ..... ... $4.95 8UX80 .......... $5 .95 8 U806 ........... $7 .95 MFE 131 ........ $2.90 MFE3001 ...... $9.90 MJ1 0012 ....... $5.95 MJ 802 .. . ..... $7.60 MJ1 5003 ....... $9.50 MJ 15004 .. ..... $9. 70 MJ 15024 ....... $9.60 MJ2Q55 . ....... $2.95 MJ4502 ........ $8 .50 MJ E'.l-10 .... ... $2 .00 MJ E350 ........ $2 .50 MJ E2955 .. .. ..$4 .90 MJ E3055 ...... $3 .90 MJ E13007 .... $4 .95 MJ E13009 .... $9 .95 MPF131 . .....$2 .90 MPSA06 ... .... $1 .00 MPSA13 .......$0 .50 MPSA42 .. ..... $0.60 MF'SA43 ... .... $0 .50 MPSA93 ....... $0.50 MPF10 2 .... .... $0.90 MPF10 9 ... .... $0.90 M PSU5 6 ....., .$1.75 PN 100 .......... $0.25 PN200 .. .... . $0.25 TIP318 .. ...... $1.00 TIP31C ......... $1.20 TI P32 8 .. ...... $1.00 TIF32C .. ....... $1 .20 TIP41A .... ... ..$1 .90 TIP41C .. ..... .. $2 .00 TIP42A .. ..... .. $1 .90 TIP42C . .... ... $2.00 TIP49 .. ......... $1 .90 TIP50 . ·· ········ $2·20 TIP53 .. .... ... $2.50 TI P 112 ..... ..... $2 .50 TI P1 16 ... .. .... $2 .50 TI P1 17 ······· ···$2 .50 TIP 120 .. . .. .$2 .90 TI P122. ... ..... $1.95 TI P1 25 ..... ..... $2.90 TIP127 ..... .... .$1.95 TIP147 .. .... $4 .95 TIP2955 ... ..... $2 .,5 TIP 3055 ....... $1.95 ~~i -,.!fim•n1 .. ,r BC107 .......... $0 .80 8C108 .......... $0 .80 8C109. .........$0.80 BC2 12 .......... $0.3 0 8C31 8 ..... ..... $0.30 8 C327 .... $0.30 8C 328 ... .. ..... $0.30 8C337 ... ...... .$ 0.40 BC338 .......... $0.40 BC 548 .. ........ $0.30 BCl547 ... $0.15 8C548 .......... $0.15 lfll N 6! 11V.. $0.25 12V..$0.25 13V..$0.25 15V.. $0.25 16V .$0.25 18V .$0.25 20V .$0.25 22V .$0.25 24V .$0.25 27V .$0.25 30V .$0.25 33V .$0.25 36V $0.25 -Description ........ $ 1N4n8 3V3 .$0.35 1N4n9 3V6 .$0.35 1N4730 3V9 .. $0.35 1N4731 4V3 ..$0.35 1N4732 4V7 ..$0.35 1N4733 5V1 ..$0.35 1N4734 5V6 ..$0 .35 1N4735 6V2 ..$0.35 1N4736 6V8 ..$ 0.35 1N4737 7V5 ..$0.35 1N4738 8V2 ..$0 .35 1 N4739 9V1 .. $0.35 1N4740 1 OV .. $0 .35 1N474 1 11 V .$0.35 1N4742 12V. $0.35 1N4733 13V .$0 .35 1N4744 15V .. $0.35 1N4745A 16V$0.35 1N4746 18V .. $0 .35 1N4747 20V .. $0 .35 1N4748 22V .$0 .35 1N4749 24V .$0 .35 1N4750 27V .$0 .35 1N4751 30V .$0 .35 1N4752 33V .. $0 .35 1N4753 36V ..$0 .35 1N4761 75V .. $0 .80 ■11;11 SW ZENER DIODE Ooscrlpt lon ......... $ 1N53398 5V6$ 1.50 1N53428 6V8$1.50 1N53498 12V$1.50 1N5358 15V$1 .50 1N5361 27V $1.50 1N5359 24V $1 .50 1N5363 30V $1 .50 1N5372 62V $1 .50 l!li~~ll·]~~ 8scnpb on....!. 1MHz ............ $6 .00 1.8432MHz ... .$7.50 2MHz ... .. ...... $3 .00 2.4576 MHz ... $2.00 3MHz ............. $4 .90 3.57954MHz .. $3 .00 4.00 MHz ... ... $3.00 4.19430MHz .. $3 .00 4.433618MHz$2.00 4.44 MHz ....... $2 .00 4.9562 MHz ... $3 .00 SMHz .... ....... $2 .00 6 MHz .. ··· ·····$2 .00 6. 144 MHz .... $3 .00 8.00 MHz .. ... .$3 .00 8.86723MHz .. $3 .00 10 MHz ... ... .$2 .00 11 MHz ..... .... $3 .00 12 .00 MHz ... .$3 .00 14.318 MHz .. $2 .00 15 MHz ..... ... $2.00 16.00 MHz .... $3 .00 20 .00 MHz ....$2 .00 2A MHz ...... .. $3 .00 48MHz . ......... $2 .00 32 .768KH• .. ., 00 ~(D=!H~ e sc npt,on 74HC00 .........$0 .75 74 HC02 ......... $0 .75 74H C04 ........$0 .75 74HC08 ........ $0.75 74HC10 .. .... ..$0 .75 74HC11 . ..... .. $0 .75 74HC14 ........ $1 .60 7>1HC30 .... .... $0 .60 74HC32 ........$0 .80 74HC42 . ....... $0 .90 74HC74 ........$ 1.10 74HC85 ........$ 1AO 74HC86 ..$ 1.10 74HC123 .. ....$1AO 74HC132 ...... $1 .25 74HC138 .... ..,1.40 74H CU7 .... .. $1 .25 74HC181 ...... $2.25 74HC184 .... ..$2.25 74 HC244 ...... $2.00 74HC 245 ...... $2.50 74HC273 ....... $2.75 74HC367 ....... $1.85 74HC373 ....... $1.80 74HC393 .... ... $2.75 74HC4040 .... $1.65 74HC4060 .... $3.95 74 HC4066 ..... $1.70 ~-%1!t1\'I'~• ! scnpbon .... ... . 4000 ..............$0.75 4001 ... ........... $0.4') 4002 .............. $0.55 4006 .............. $1.55 4007 ... $0.45 4008 ..... ······$1.70 4009 ............. $0.90. 4010 ... $0.90 4011. ..... $0.45 40.12 .. .......... $0 .45 4013 .. . ... ... $0.70 4014 ........ ..... $1 .00 4015.. ... $0 .90 4016 ......... $0.70 4017 .... .........$1.35 4018 .............l0.50 40 19... ..$0.80 4020 ...... .... ... $1.40 4021 .............. $1.50 4022 ... . ... ...$1.45 4023 .............$0.45 4024 .. ....... $1.60 4025 ............. $0.45 4026 ............. $1.10 4027 .. . .. ..... $0.85 4028 .. ....$1.15 4029 ............. $1.50 4030 ...... $0 .50 4033 .. ........ $2.75 4038 ..... ... .....$2 .25 4040 .. . ...... $1.20 4042 .. . ..... $1.50 4043 .... ........ $1 .20 4044.. ..... $1 .25 4045 ............. $4 .90 4046 ............. $1.00 4047 .. ..... $1.90 4049 ............ $0.60 40 50 ........... .. $0.60 4051 .. ... $1. 20 4052 ·•· ......... $1.20 4053 ... . ..... $1.20 4060 ·············$2.50 4066 ..... ..... ... $0 .80 4068 .. . ... $0 .50 4069 .. ... ..... $0 .50 4070.. . .... $0 .50 4071 .. ... ..... $0 .50 4073 ·········'°·50 4075 ............. $0 .50 4076 .... $1.90 40n ............. $0 .50 4076. .. . . ... $0 .50 4081 .. ···· ···$0 .50 4082 ............ $0.50 4093 .. ........... $0.80 4098 ..... ........ $1.90 45 104 .......... $7.25 4503 . ........... $1.:30 45 10 ..... ........ $1.40 4511 ......... ..... $1.45 4512 ..... ... .... $1.40 4514 ............. $2 .60 4515 .. ..... $1.90 4516 ............ $1.60 4518 ..... ..... ... $1 .50 4520 .. . .. .... $1.00 4522 ............. $1 .90 4526 4528 4532 4536 ............. $1.00 ............. $1.95 ..... ........ $2 .65 ..... ..... ... $6.50 4538 .... ... ... ... $1 .20 4543 .......... ... $2 .50 4556 ............. $1.25 4584 .. . ...... $1.00 40014 ........... $1.50 40175 ........... $2.00 74COO ..... ..... $1.00 74C04 ........... $1 .00 74C08 ......... $1 .00 74C14 ........... $1.75 74C74 ........... $1 .00 74C86 ........ ... $1 .50 74C90 .. ...... .. $2.50 74C192 ...... ..$3.50 74C22 1 . .... .. $3 .85 74C244 .. ..... $3.95 74 C373 .. . ... $8.95 74C906 .. ...... $2.90 74C922 ...... $14.95 74C926 ...... $13.95 74C946 ...... $24.50 lit!wjjt.1 74S04 ......... .. .$1 .20 74S08 ......... ...$1 .50 74S30........ ....$1 .00 74S32 ............ $1 .00 74S132 .... ...... $3.50 74S133 .......... $ 1.20 74S138 ...... .... $2.50 74S 139 .... ...... $3.30 74S 174 ..... .... $3.50 Ulldwt1 :i., t.4fi1; 1 ?.'. 7400 .......... .... $0 .80 7402 ...... $1.00 7403 ..... ......... $1 .00 7404 .............. $0.30 7406 ............. $0.40 7407 .. . ... $0 .50 7408 ............. $1.00 7409 ... $1,00 74 10 ............. $1.20 7414 .. ....... $1.50 7416 ............ $0.50 7430 ............. $ 1.00 7432 ............ .$1.00 7438 .............$0.80 7442 .............$1.50 7445 ........... .$1.00 7446 ...... ... ....$1.20 7447 ....... .. .. $1.75 7473 .. .. .........$1 .20 7474 .. ...........$0 .40 7475 .............$1 .20 7478 ............. $1.50 7483. . .. ....$1.10 7490.. ..$1 .20 7493 ......... .... $ 1.25 fZ!l-;.l-•1jj11:S."1 t!.ln),on?f 74 LSOO ... ... ... $0.:30 74LS01 ..... .... $0 .60 74LS02 ......... $0.60 74LS03 .. ..... $0.60 74LS04 ......... $0.75 74LS05 ..... .... $0.75 74 LS08 ... ... ...$0.60 74LS 10 ......... $0.:30 74 LS11 ......... $0.75 74 LS13 ... $0.90 74LS14 ... $0.75 74LS15 . ....... $0 .80 74LS20 ......... $0.90 74 LS21 ....• ... $0.90 74LS27 ........ $0.90 74LS30 ... $0.30 74 LS32 ... $0.60 74 LS379 ... $0. 70 74LS38 .. ...... $0.80 74LS42 74L S629. 74LS640 8Scnpbon ... 74F00 ............ $0.25 74F04 ............ $0.25 74F32 ..... $0 .25 74F74 ..... .$0.25 74F109 .......... $0.50 74F138 .... ...... $1 .00 74F151 ......... $1 .20 74F153 .......... $1.20 74F157 .......... $1 .20 74F194 ...... ....$2.41 74F244 ..........$3.·'2 7412 1 .......... .$1 .55 74123 .......... $0.50 74125 .. ...... $ 1.00 74126 .......... $ 1.00 74150 .. ... ...... $ 1.90 74154 ..........$2 .50 74157 . .......... $1.30 74161 ...... ...... $1.20 74164 .......... $1.20 74177 .. ... ...... $1.95 74193 ........... $1.50 74195 ........... $1.00 74197 ........... $ 1.20 74283 . ...... ... .$2 .45 74290 ... $0 .90 11 tP'Kf-,.p Description .. .... ... . ...$1.20 $ LM394CH ... ... $7 .95 LM39ST.... ...... $9.95 !. M395K ......... $7 .95 LM396K ....... $16 .50 LM399H ..... $7 .so LM711 ......... .$1 .20 LM725 ... .. .... $7 .50 LM733 .......... $ 1.50 LM741 .. .. ..... $0.60 LM747 ........... $1 .50 LM748 ........... $1.1 0 LM759 ....... .... $3.90 LM833 .. ........ $2.1 0 LM1830 ....... $4.90 LM1871 N....... $7 .50 LM1872N .. ... $8.60 LM1886 ...... .... $9 .10 LM2907·14 .... $3 .50 LM2907-8 ...... $5 .10 LM2917-14 ... . $2 .50 LM2917·8 .... .. $4 .80 LM3900 .... .... $0 .80 . LM3909 ......... $2 .50 LM39t1 ....... .. $3.95 LM3914 .. $2 .90 LM3915... .. $2 .90 LM3999Z ..... . $5 .95 LM 4250 .... .. .. .$2 .45. LM11CN .. ... .. . .$4 .95 LM 13600 ........ $2 .70 LMC555 .......... $ 1.25 MA X23211CC232 HMC232 .......$11 95 OM350 .......... $21 .00 MC1408L8 ...... $7 .50 MC 1458 ........ . $1 .20 MC1488 ...... . $0 .60 MC1489 ......... $0 .60 MC1496 ......... $2 .50 MC3334P.... ... $6 .95 MC34018P.. ... $8 .95 MOC302 1 .. .... . $1 .95 NE555.. .. $0 .50 NE556 . $0 .95 NE558 ...... ..... $6 .50 NE564 .. .. ...... $7 .00 NE566 ............ $2 .90 NE557 ........... $2 .00 NE570.. . ... $8.95 NE571 ......... $6.95 NEsn .......... s 11 .20 INS82SON .. .. $ 18. 10 TA 7205P..... ... $2 .95 TDA 1024 ... .... $ 3.90 TEA1002 ....... $17 .50 TL064 ....... ...... $2 .10 TL0711 LF351 . $1 .20 TL072/ LF353 . $1 .60 74LS47 .. ... $1 .80 OACOBOO ........ $4.95 74 LS48 ... $1 .80 0 ACOB08 ........ $4.90 74LS74 ...... ... $0.40 AOC0800CN .. $29.95 74LS75 $1 .20 AOC0803 ...... $13 .50 74 LS76 ... $1.00 AOCOB04 ......... $7.95 74LS85 .... ..... $0 .85 ADC0808 ....... $13.00 74LS86 .. ...... $0.60 AOC0820LCN.$27 .95 74LS90 ... $1 .20 OAC0832 .... ..... $7 .95 74LS92 .$1 .20 OAC1020 ....... $16.28 74LS 93 ... $1 .50 11C90 .......... $16 .50 TL074/ LF347 . $1 .40 74LS95 .. $1 .20 0AC 1220 . . .... $22 .95 TL081 ... $1 .90 74LS107 ... ... $0.90 OAC1408 ... ..... $1.00 TL082 ............. $2 .20 74LS109 ... ... $0.90 A D590J ........ $12 .95 TL084 ......... .... $1 .50 74LS112 . .$0. 70 UA710CN ....... $1.00 74LS123 ...... $1 .30 UA739 ............. $2 .75 74 LS125 ... $1 .00 UP08288 .... $16 .50 74 LS126 ....... $1 .00 XR2206 .......... $9 .95 74LS132 ... . ..$1.00 XR2209 .......... . $6.90 74LS138 ...... $0.80 .AY-3 -101 s ..... $11.95 . XR221 1 ........ .. $7.95 74 LS139 ....... $0.80 .AY-3· 8910 ..... $19.95 XR2216 ..... ...... $5.90 74LS145 ....... $1.50 .AY-5-8 11 6 ..... $14.50 XR2240 ... ....... $ 6.95 74 LS147 ....... $2.50 CA3028... . .. $3.95 XR2243 .......... $5.95 74L S151 ......$1.20 CA3086 ... ..... $1.20 26LS30 ... ..... . $2.00 . 74LS153 ....... $1 .00 CA3130E ....... $2.90 26LS31 ... ...... . $2.00 74LS155 ....... $0.50 CA3130T... ..... $3.95 26LS32 .......... $2 .00 74 LS156 ....... $1 .50 CA3140E .... .... $1 .30 5534AN .......... $3 .95 74 LS157 ...... $1 .20 CA3140T... .. .. $2 .95 74LS158 ....... $1.00 CTS256A .... . $45 .60 . 8155 ... ··········· $8 .95 OM2502 ...... $13 .60 8156 .............. .$8 .50 74LS160 ....... $1 .50 LF347 ............ $1 .40 81LS95 .......... $1.00 74LS161 .. ..... $1.00 81LS96 .. ......$2 .75 74LS162 .......$0 .50 LF351N ......... . $1 .20 8216 .............. $3 .00 74LS 163 ...... $1 . 10 LF353 ............ $1 .60 8237 . ....... ..... $14 .50 LF356N ......... $1 .50 74LS 164 ...... $1.40 LF357 ... ...... $2 .95 8255 ............... $6 .90 74LS165 ...... $1.20 LF398.. . . . $5 .90 8279 .............. $8 .50 74LS 166 .. .... $1.25 ..... $6 .95 LM301H ...... .. $1.50 8830 74LS168 ....... $2.10 LM301N ... ...... $0.50 9SH90 .. ....... .$10 .50 74 LS174 ....... $1 .20 LM302H ..... . . $6.50 9667 ............ .. $0.90 74LS175 .. ... .. $0.70 LM305H.. ..... $1.50 9668 . .... ... $2 .95 74LS181 ... .. . $4.00 LM307CN ...... $1.50 74LS191 ....... $1 .20 LM308 ..... .. .. .. $0.50 74LS193 .. ..... $1 .20 LM309K ... .. ... $2.85 74LS195 ..... $0.50 LM310N ...... ... $4 .95 74LS196 .. ..... $1 .20 LM311 ..... ...... $1.00 74LS22 1 .. ..... $2.00 LM324 ... . ...... $1.20 S240 ....... $1 .40 LM331 ..... .......$6 .00 t . ..... $0.95 LM339 ... ... ..... . $0.60 ., ,,,J ...$ 1.10 LM348 .. . ....... $1.00 74 LS 244 .... $2 .20 LMl49 ........ ... $2 .95 74LS245 ... ... .$2.95 LM358 ............ $1 .40 74LS257 ....... $1 .20 LM3F1 .. .. ...... .. $4 .95 74LS258 ....... $1 .20 LM380N·14 ... . $1.95 74LS259 ..... .$2.25 LM380N·8 ... .. $1 .50 74 LS266 ...$0.70 LM36 1 ............$4 .95 74LS273 .... ... $ 1.00 LM382 .... ........ $3.50 74LS323 .. .. ... $6.50 tl11lfl1·li._ 74LS352 74LS365 .. 74LS368 74 LS387 74LS373 11!1liil'li~·~ LM317T. ......... $2 .50 LM317KC .... ... $5.50 LM320K12 ..... $1.40 LM320 K-05 .... $3 .00 LM320T-5 ...... $1.40 LM323K ········ $9 .50 LM326 ........... $5 .50 LM3290Z ...... $0 .90 LM334Z . ...... .. $1.70 LM335Z .... ..... $2 .50 LM336Z-2.SV. $2 .95 LM350K. .. - 1M·08 .. ........ $14 .95 _]J_ ~\ \ ~· ---\ • $11 50 ~ r 78 L12... $0 .75 78L15 ... .$0 .75 79L05 .. .......... $1 .20 1M X 9-80 .. $125.00 1M X g.7Q .. $129 .00 79Ll2 ........ . ... $1 .20 79L15 .. ... ....... $1 .20 •:~11~,, LM396K ....... $16 .50 Wil:W+W Description ... .. $ 9-80 .. $49 .00 Desc ription. $ 76489 ...... ..... $12 .50 ICL7660 ..... ... . $6 .90 VN88A F. .........$5.95 MM5369 ......... $4.95 1M X 9-80 .... $125.00 1M x Q-70 .... $12Q.00 1n·r1a•i13;1 ! ,pt on 5502A ........... $16.96 6522A ....... .... $15.95 6802. .. $7.00 6809 ......... ..... $ 17.00 6821 ............ .... $5.50 6845 ....... ... .... $9 .95 6850 .............. $3 .50 7910.... $29 .95 8035N-6 ......... $6.90 8039 ............... $9 .90 8080 ............... $8 .00 8085A ...... $16 .50 8088 .. ··· ·•····· $12 .50 ICL7106 ..... .. $15 .95 ICM7216B .... $59 .50 LF13741 ........ $0.80 NS 16450 ..... $26 .95 S3530 .... ... $24.95 S P0256 .... ... $21.95 TR1863 .......... $8 .90 V20A ....... .... $35.95 V20 ... ..... . ... $29.95 W0 2123 ..... .. $29 .85 XR80 38 .......... $7 .50 Z80A CTC ..... $8 .50 Z80 8 CPU ... $13 .50 Z80A CPU ... ... $5.75 Z80A PIO ..... .. $4 .50 Z80A S IO .... $14 .50 Description .......... $ 3 mm L EOS Rod ................. $0 .20 Groe n ....... ..... $0 .30 Yellow ............ $0 .30 Orange ........... $0 .30 5mm LEDS Rod .......... ... .. $0 .20 Gree n ... ........ $0 .30 Yello w .... ........ $0.30 Orahge .......... $0 .30 1Clmm JU MBO LE ADS Rod .... ............ $1 .50 Gree n ............ $1.50 Orange ........... $1.SO S UP ER BR IGHT LEO S Rod . ........... ... . $1.00 GrHn .......... .. $1.00 Yel low ....... ..... $1 .00 Smm FLASHING LE OS Rod ................ . $1 .25 RECTANGLE LEOS Rod ..... .... ...... . $0 .25 GrHn ........... $0 .30 Yello w .. .. .. .. ... $0 .30 Orange . $0 .30 5mm RED/GREEN DUAL LEO .... $1.05 8087-2 ... $279.00 8087-1 ...... $379.00 80287•6 .... $249.00 802 87-8 .... $379.00 80287-10 ... $459.00 80387-16 .... $695.50 80387-20 . .. . $795 .00 80387·25 ... $8Q6.00 80387-39 ... .$995 .00 i Prices a re 1-9. I I I I I I I I 10-99 less 10%. 100+ less 20%. I I I I I I I I p I ~ ~ ~ LM386-1 ...... ...$1.40 LM390 .... ...... . $2.9b LM392 . ... .... .. .. S1.50 . ~ -~,. ~,/ / " - " J / ' --~ A_ 7 L----------.J 7•LS375 ...... $1.00 l . ,. 7BP05GC ..... $14 .50 7805 ... $0 .75 Descn t.i11on $ 256 X 9-80 . ... $49 .00 008 335757 TOLL FREE MAIL ORDER HOTLINE FOR CREDIT CARD ORDERS! I /.' :t LM378 .. $6 .95 TL494 ... $4.90 LM723CH .. $1 .50 LMn3CN ... .. $0.95 78HGK ........... $9.50 1M• 10 ........... $13 95 LM367 ........ .... $2.75 7'LS374 .. ... ..$2.00 - r- LM337KC .... $12 .50 LM338K ........ $9 .45 LM340T-5 .. $0 .90 LM340KC·S ....$2 .95 LM340T-5 ..... $0.90 LM340KC·5 . .. $2 .95 LM340T•12 .... $0 .90 Lf.4 l40T-1 8 ... $2 .00 LM340T-15 .. .. $0 .90 LM340KC-12 $4 .95 LM350T.... $8 .40 8264 LP ·10 .. $19 95 62256L P-10 . $39 95 X ~ ~ L M 33625 .0V. . $2 .95 L M337 T. ........ $2.90 44256-08 .. ... $14 .95 44256-07 ... ... $15 .95 6116 . $5 .50 256K t.I l[iliS · J-lit-Z ! scnptJo n ...... $ i cnp o n ; 2114 ............ .... $5.20 2716 ..... $12 .50 2732-200 .... .... $8 .25 2764-250 ....... . $8.95 27128 ........ .. .. $8 .00 27256-250 .. .... . $9 .50 275 12-250 . ... $14.95 27-1MEG ....... $29.50 27C64-200NS. $8 .95 27C1 28 ......... $12.50 27C2561 250NS .. ...... .. $15.50 27 C512 ........ $22.50 27C 1M EG ... $34.50 41 16 16K ....... $ 3.95 4164- 10 ... $4.95 4464- 10 ....... . $5.50 4464·08 .. ........ $5 .90 41256 · 10 ........ $4 .95 41256-08 ... ..... $5 .50 44256-10 ... ... $13 .95 LM383 .. ... ... .... $4 .95 LM384 ............ $3.50 ... $2.20 ... .$1.00 ...$1.00 ... $1.00 ... $2.00 " ___......- JA . . 1 N747A 3V6 .$0.25 1 N748A 3V9 .$0.25 1N749A 4V3 .$0 .25 1 N750A 4V7 .$0.25 1 N75 1A SV 1 .$0.25 1 N752A 5V8 .$0.25 1 N753A 6V2 .$0.25 1 N754A 6V8 .$0.29 1 N755A 7V5 .$0.25 1N758A 8V2 .$0.25 1N787A 9V1 .$0.25 1N758A 10V .$0.25 1N962A 1N759A 1N964A 1N9658 1N9668 1N9678 1N9688 1N9698 1 N9708 1 N9718 1N9728 1 N9738 1N9748 r-1 ·1>-/-F> I Snowy River and the Island BendEucumbene tunnel. This reverse flow mode is only used in times of heavy precipitation on the Mt Kosciusko areas and then only provided the Geehi River and reservoir alone can provide enough water for the Murray 1 and Murray 2 power stations. Finally, (5) water can pass by reverse flow in the Tumut Pond-Lake Eucumbene underground tunnel. This mode is only used when snowmelt/ rainfall in the upperTooma and Tumut rivers catchment exceeds the water requirements of the Tumut 1, 2 and 3 and Blowering power stations. Tumut Pond is also fed by another tunnel from Tooma Reservoir plus four vertical intakes from smaller streams under which the tunnel runs. Eucumbene outflow ;:, ,I,{,. The first dam to be built on the Snowy scheme was Guthega, shown here in the early construction stages during 1954. The associated Guthega power station was also built during these early years. wall is enormously thick, tapering ·in section from 686 metres at the base to just a roadway's width at the crest. Complex design Some idea of the complexity of the Snowy scheme can be gained when we consider the 4-way water flow pattern into and out of Lake Eucumbene. The overall design purpose is to: (1). Always provide sufficient water flow down the Murray & Tumut rivers for downstream towns and the Murray and Murrumbidgee Irrigation Areas. To meet these requirements, the whole scheme provides an annual equivalent of 2,350,000 megalitres of water. (2). Store enough water to generate 98 SILICON CHIP sufficient electricity for the ACT and to assist NSW, Victoria and South Australia with their peak load requirements. (3). As far as possible , prevent downstream floods and wastage of excess rainfall and snowmelt by storing all surplus precipitation in Lake Eucumbene for later use. Water can flow into Lake Eucumbene from five different sources: (1) from the Eucumbene River and its tributaries; (2) from rainfall/snowmelt on the mountains surrounding the lake; (3) via an underground tunnel from Tantangara Reservoir on the headwaters of the Murrumbidgee River; (4) from Guthega Pondage via Guthega power station , the upper In dry times , the Tumut and Upper Tooma rivers cannot provide enough water for the Tumut-Blowering power stations and downstream Murrumbidgee irrigation areas. Also, during droughts, the Geehi river is insufficient for the needs of the Murray 1 and 2 power stations and the Murray irrigation system. In such conditions, the vast storage of Lake Eucumbene is the saviour of the whole system. Water then flows by tunnel from Eucumbene via Happy Jack to Tumut Pond, thence through the three Tumut power stations to Blowering and on downstream. Also, to supply the Murray system, water flows by tunnel from Lake Eucumbene to Island Bend and then by tunnel to Geehi and on through the Murray 1 and 2 power stations. Jindabyne storage Precipitation falling in the catchments of the Crackenback River, the Snowy River below Island Bend and the lower Eucumbene River is stored in Lake Jindabyne. This lake is third in storage size in the scheme and holds 689,790 megalitres of water. Riparian rights (ie, irrigation and fishing rights) in the Snowy River below the dam is provided by a 914mm diameter siphon. To cope with floods , twin balanced radial gates can open a spillway capable of passing approximately 3000 cubic metres of water per second. The operation of these huge gates is fully automatic and is controlled by the height of the water in the dam. SECTION THROUGH GUTHEGA POWER STATION RL4422 120 TON OVERHEAD TRAVELLING CRANE --ttH---t::r::i:'lE:r:::I SCALE OF FEET This cross-section diagram of Guthega power station shows how water drives the turbine and the 30 megawatt generator. Water enters at the side and leaves the turbine from the bottom. The challenge to the engineers of the Snowy scheme: harness the vast catchment of these rugged mountains so that the water can be used for electricity generation and agriculture. They succeeded admirably. The function of Lake Jindabyne is to store Snowy River water for subsequent passage westward in tunnels under the mountain to Geehi Reservoir via Island Bend. But as the transmountain tunnel is 231 metres higher than Jindabyne, the water is pumped up to this height using cheap electricity in the middle of the night. Because of cavitation effects, lift pumps are unsatisfactory (and impossible above about 10 metres oflift). As the main Jindabyne pumps are located 20 metres above the water stor- age, booster pumps are installed below minimum dam water level. These booster pumps at the foot of the pumpwell are driven, via long vertical steel shafts, by 7.46MW (10,000 horsepower) induction motors mounted up in the pumphouse. The 40MW (53,600 hp) main pumps are horizontal shaft double suction single stage centrifugal types, capable of pumping 13 cubic metres of water per second against a 232 metre head. These are driven by llkV synchronous motors. The starting procedure for these motors is interesting, particularly when one considers that the water pressure due to the 232-metre head is always present at the foot of the Jindabyne-Island Bend tunnel, whether the pumps are running or not. To avoid any power surges when the pump motors are started, an auxiliary pelton water turbine, driven by this 231-metre water head, is used to get the main motors up to speed. The supply transformers for these 1 lkV motors are oil filled but they are cooled by heat exchangers in the pumped water stream. During times of excessively high flow in the Geehi river, water from this western source can be diverted backwards via the trans-mountain tunnel for storage at Jindabyne. Rivers like the Geehi, flowing in precipitous mountain gorges, have tributaries falling from great heights. Many of these enter the Geehi below the dam yet the bulk of their length is at greater elevation. Therefore, high up the rocky cliffs, aqueducts, tunnels and buried pipelines catch much of this water and shunt it back for storage in the dam. Construction of the Jindabyne pump system began in March 1966 and was completed in the summer of 1969. Of the seven power stations in the final design, Tumut 1 and Tumut 2 are underground, deep within the granite and granitic gneiss mountain formations. The remaining five stations Tumut 3, Blowering, Guthega and Murray 1 & 2 - are above ground. Individual station power ratings range from 60MW (Guthega) up to 1.5GW (Tumut 3). The first steps The first step was the essential detailed survey. Accurate measurements were taken of rain, snowfall and snow JULY 1991 99 SECTION THROUGH JINDABYNE PUMPING STATION 75-TON OVERHEAD TRAVELLING CRANE FSL LAKE JINDABYNE RL2990 FOUNDATION EXCAVATION LINE LAKE JINDABYNE 20 0 20 40 60 SCALE OF FEET depth. Above 1400 metres, the precipitation falls as snow in winter and is up to three or four metres deep on the highest areas. On-site measurements supplemented by local knowledge gave information on snowmelt runoff periods. The dominant runoff cycle begins each year in August, peaking in September and October. Peak monthly stream flow varies from 400 million cubic metres in a dry year to 1.5 ,billion cubic metres in wetter times. Because of the height of the Snowy Mountains, their stream flow varies less in wet-year/dry-year ratio than other Australian rivers. This fact enhances the reliability of the hydroelectric installations. While surveyors established detailed ground levels, geologists measured the deep rock structure. A thorough knowledge of the type, age and condition of subsurface strata and the location of faults was essential before the precise locations of power stations and dams could be decided. Also, the geological foundation vastly influenced the type of dam chosen for each site. 100 SILICON CHIP A fluid mechanics laboratory set up at Cooma test-proved the proposed designs for dams and spillways. Construction begins The geology near Mt Kosciusko is a mix of basalt lava flows, older clays and gravels overlaying ancient bluegrey granite up to 500 million years old. In places, glacial moraines show the only evidence on the mainland of past ice ages that occurred some two million years ago. It was in this type of area, 13km from the highest point in Australia, that the first dam and power station of the Snowy Mountains system was built. The Guthega Dam foundations were dug in the bed of the upper Snowy River at the beginning of December 1951. As with most of the Snowy sites, conditions were very difficult. The straight concrete gravity dam , rising a mere 33.5 metres above its granite foundation, holds back 1548 megalitres of water, at 1582 metres above sea level. The Guthega power station is supplied from the dam by a 5.87-metre wide horseshoe shaped underground Pumped water storage for later use during peak electricity demand periods is a key element in the function of the Snowy Mountains scheme. The two pump stages in the Jindabyne Pumping Station are used to lift water some 230 metres up to Island Bend pondage. pressure tunnel ending in two penstock pipes, in all totalling 5.5km in length. The penstocks reduce in diameter from 2.13 metres at the top to 1.52 metres at the bottom as the water velocity increases. To withstand the pressure of the 247-metre head of water, the pipes at the lower end of the penstocks are constructed from 24mm steel plate. Within the power station, two 3 lMW Francis vertical shaft water turbines together use about 40 cubic metres water per second to drive the alternators. Rotating quietly at 428 rpm, the two alternators together contribute 60MW to the system grid. The generated 1 lkV is stepped up to 132kV for tran.:;mission to Khancoban, Jindabyne and Cooma. That's all for now. We'll resume our story of the Snowy Mountains Schernfl next month. Acknowledgement Special thanks and acknowledgements to Libby Langford and the Snowy Mountains Hydroelectric Authority for data, photos and permission to publish. SC 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. Sensing the low signals from a CD player I have a unit built from a magazine article published about 10 years ago which I find very useful. It monitors the signals at the tape output of the amplifier and if no signal is present for around 30 seconds or more, it shuts off the AC mains supply to all the equipment. The problem is that it doesn't work with the very low signal levels that can come out ofmy CD player. When the CD player is in use, the signal level can be so low that the poor little auto switch thinks that everyone has locked up and gone home, so it shuts down, too. I have tried varying the R2 resistance (article enclosed), but it gets a bit too sensitive and "Voxes" on when I don't want it to and still shuts down on quiet CD passages. Could you give me a little advice on what to do with it? (No, not that kind of advice)! Maybe even an updated design would be a worthwhile project. I know I built quite a few for nontechnical friends who saw mine. (P. S. Nerang, Qld). • CD players do present a problem for this type of circuit because of their potentially low output signals. The way to get around the pr!:>blem, as far as your existing cirtuitis concerned, VU meter for stereo equaliser I have recently purchased the Studio Series 20-Band Stereo Equaliser, described in the August and September 1989 issues, and was wondering if it is possible to tap into the output of each gyrator circuit and drive a LED VU meter circuit, similar in design to the one used by your 1.6-Channel Mixing Desk (Feb-May 1990). The potential VU meter would add some life to my system and will impress may be to increase the delay by increasing Cl which determines the 30 second delay. Try a value of 50µF or lO0µF. However, that modification will only work if the CD player is actually playing. If you pause the CD player to allow for a temporary interruption to your music listening, the monitoring circuit will then sense that no signal is present and then shut down the system. The only way around that problem is to sense whether the CD player's drive motor is actually running (as it does in Pause mode). This would require an internal connection to the motor itself which you may not regard as desirable. Mixer preamp for a 300 watt amplifier I would like to make a mixer/ preamp for a 300 watt amplifier which has two 1V inputs (stereo). This mixer/ preamp will be in its own case with a power supply and have six balanced microphone inputs, two tape deck inputs and two tape deck outputs. Your article on the 16-Channel Mixing Desk in the February and March 1990 issues uses LM833 low noise dual op amps and I would like to know which circuitry to use but ex- visually as well as giving an indication of the sound output. (M. P., Hurstville, NSW). • You should have no problems connecting the LED VU meter circuit from our March 1990 issue directly to the output of your equaliser. However, you will have to make sure that the power supply in the equaliser can cope with the additional current drain of all the LEDs. As it stands, the power supply in the equaliser is not big enough. At the very least, you will require a bigger transformer. eluding effects, foldback, LED VU meter and the unbalanced microphone inputs for a start? Having a headphone jack per channel makes it easier to find noise due to microphone cable breaks at connections. Also, I would appreciate it if you could give me some information on 70 and 100 volt public address systems. They are often installed in halls and auditoriums and when you only have a conventional mono or stereo amplifier it is like running into a brick wall when you have only a limited time to set up. (R. T., Monto, Qld). • Your mixer preamp could make direct use of the input channel boards and the equaliser/VU board with the VU meter circuitry left out. Leaving out the unbalanced microphone facility is very easy - just omit the 3rd position of the input selector switch Sl for each input channel board. We have not published an article specifically on the subject of 70 and 100 volt lines although some aspects were covered in the articles on the 120 Watt PA Amplifier in the November and December 1988 issues of SILICON CHIP. These articles will at least give you the general idea. What price the mystical blue LED? Whilst sorting through my parts junk box, I came across an item that was definitely not junk. At first I thought there was a burned out red LED lurking in the shadows of the box but on closer inspection (simply picking it up and looking) I began to salivate (drool-dribble) and when I took it round the traps, I had the same reaction from many people. What was/is it? None other than a blue LED, yes blue. My poor wife who at one stage was an electronics widow, only ever seeing me through clouds of smoke from the soldering iron, and forever shovelling bits and pieces off the lounge table, dining table, and every flat surface in the house, has started a habit JULY 1991 101 of collapsing to her knees and praying in the general directions of electronic manufacturers in the hope that they don't make blue LEDs. My question is: where can we buy them? (M. M., Blackburn, Vic). • They are available, but at out-ofthis-world prices, from Siemens in each state. Their address in your state is 544 Church Street, Richmond 3121. Telephone 420 7111. Speed control for electric flight models I am an aircraft modeller from way back - about 28 years. Recently, I have become involved in electric flight which is a very challenging and .eyeopening experience for an aeroplane (read: combustion engine) nut. I have just completed one of your projects, the Fast Nicad Charger and, to my complete amazement, it work_s perfectly. I built it from scratch, etched the PC board myself and had about 50% of the components in my junkbox. Thank you and your R & D staff for such a nicely presented, intelligent project. Now I face another problem - speed control. I have built an ON-OFF relay switch operated by an R/C set but the challenge of a fully proportional speed control for an electric motor in a model aircraft has set in. To date, I have destroyed numerous (and expensive) MOSFETs, one motor, four fuses and an ammeter. About 12 years ago , I built a proportional forward/reverse speed control for electric boats. The silicon bridge and transistors took about 1V out of supply! This is not acceptable for aeroplanes drawing 7-15 amps at the 7.28.4V available. The NE544 servo amplifier is a great workhorse but isn't suitable for driving "expensive" MOSFETs . I am obviously not doing the right thing! A commercial speed control (imported) is in excess of $250. This is a bit too steep for the average modeller. Electric model cars obviously have the numbers, but "boaties" and R/C builders count as well. An "Aussie" developed speed control operated by an R/C set would be a boon. With environmental groups giving us (IC engine modellers) a hard time due to noise pollution, electric power is the way to go. What I and a lot ofmy flying mates are looking for is a speed 102 SILICON CHIP Power supply for security alarm Recently, I completed building my alarm system complete with keypad and steel case but I lack a power supply with battery backup. I have the September 1990 edition of Silicon Chip which has a power supply for an alarm system. The only problem is that I have already purchased a 12 volt 1 amp regulated power supply for my alarm. What I want to know is how to use the back-up and charger circuit from your September 1990 issue while employing the power supply I have at the moment. One last thing I would like to ask is what would the charge rate be for a 12 volt 2.6 amp/hour lead acid battery and a 12 volt 6 amp/ hour lead acid battery and how much current would I need to trickle charge each of these batteries? What value resistors would I need to charge these batteries from a 12 volt 1 amp power supply? (A. A., Moorabbin, Vic). • Since we do not have the details of your power supply circuit, we cannot give you a list of the modifications that will be required. Essentially though, the published power supply circuit needs an AC input of somewhere between 1218V AC. Your power supply should at least have that. It is then a matter of connecting the lowvoltage AC from your power supply to the PC board for the alarm power supply. As far as lead acid batteries are concerned, it is normal practice to charge them at the 20 hour rate. For example, a 6 amp/hour battery control for 05-size electric motors (buggy size), forward only, optically coupled, with a break circuit. If you can help, great. If you can't, I'll just keep the MOSFET suppliers happy and hope for the best. Thanks for a great magazine. (J. N., Hoppers Crossing, Vic). • Thanks for your comments about the Fast Nicad Charger - it does work well. We hope to so some work on a proportional speed controller for electric flight models and also for model would be charged at around 300 millianips for 20 hours. We described a charger especially for sealed lead acid batteries in our March 1990 issue which had trickle, charge and float modes. The value of resistor needed to charge these batteries really depends on how much you want the charge to be and the open circuit voltage of your power supply. If your power supply delivers exactly 12V, then it can't charge a 12V battery. You need a power supply with an open circuit voltage of something like 16-20V DC for charging to take place. The normal practice when designing a battery charger is to use a transformer with an open circuit secondary voltage of 17-18 volts RMS, giving a peak voltage (on the sine wave crests) of about 24 volts after rectification. Then, if you assume that a battery on charge will have about 13 volts DC across it, you can select a suitable resistor (or use the transformer's secondary resistance) to limit the charge current. For the example you are interested in (ie, a 12V 6 amp/hour battery with a 300 milliamp charge rate), a resistor of around 2 7Q rated at 10 watts should be about right. However, you should then make sure that the battery is not overcharged otherwise it may be damaged. For "trickle charging" a battery of this size, a current of no more than 20 milliamps is indicated. For this current, a resistor of 560Q is called for. In reality though, we much prefer the special charger described in the March 1990 issue. boats in the near future - possibly in the latter half of this year. Notes & errata Stereo Audio Expander, May 1991: the circuit diagram on page 26 shows the rectifier diode D2 the wrong way around while the wiring diagram on page 27 shows the 3-terminal regulator connected the wrong way around. The photo on page 27 shows it correctly connected. SC MARKET CENTRE Cash in your surplus gear. Advertise it here in Silicon Chip. FOR SALE WEATHER FAX programs for IBM XT/ ATs *** "RADFAX2" is a high resolution, shortwave weather fax, Morse & RTTY receiving program. Needs CGA, SSB HF radio & Radfax decoder. Also "RF2HERC", "RF,2EGA" & "RF2VGA", same as RADFAX2 but suitable for Hercules, EGA & VGA cards respectively. $35. *** "SATFAX" 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 5.25-inch or 3.5-inch discs (state which) & include documentation. Add $3 postage. Only from M. Delahunty, 42 Villiers St, New Farm, 4004 Old. Phone (07) 358 2785. LAB LASERS. 0.5mW to 2mW HeNe lasers complete. Ideal for students or hobbyists. Australian made. $440- $640. Phone M.C.E. Lasers (03) 357 0055. XT/AT HANDBOOK by Choisser & Foster. Pocket size, 92 pages. For engineers & programmers, & other serious PC/XT & PC/AT users. A collection of hardware & software facts & data on the PC compatible family & its operat- 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. If you use a PO Box number, you must include your permanent address and phone number for our files. We cannot accept ads submitted without this information. To run your classified ad, print clearly on the lines below or on a separate sheet of paper & send the form together with your cheque or credit card details to : Silicon Chip Classifieds, PO Box 139, Collaroy Beach, NSW 2097. Or fax the details to (02) 979 6503. Enclosed is my cheque/money order for $_ _ _ _ or please debit my 0 Bankcard 0 Visa Card 0 Master Card XI I I Signature_ _ __ _ __ _ _ _ _ Card expiry date_ _~ /_ __ I I Name _ __ _ __ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __ I I Street _ _ _ _ _ _ _ _ _ _ __ _ __ _ _ _ _ _ _ _ __ I I Suburb/town _ _ __ _ __ _ _ __ _ Postcode_ _ _ _ __ I L _________________________ J Card No. ing system. Latest edition. This is the one advertised by Annabooks in the US magazines Byte, Dr Dobb's Journal, etc. $20 including postage. Five or more $15 each. Don McKenzie, 29 Ellesmere Crescent, Tullamari_ne 3043. KIT REPAIRS. No job too small, fixed price & free quotes. Warranty on all repairs. Construction & design service also available. Phone (02) 649 2134. MAINS FILTER SPECIAL. Compact unit with an IEC socket, only about twice as long as a standard IEC socket. Not just a cheap filter that has a few capacitors. This unit includes two 1.7mH inductors & three capacitors in a shielded metal can. Has spade output connectors. Its 240V/3A rating means that it can supply up to 720 watt loads. With every filter, we will include a 140 joule varistor as a free bonus! That makes the pair about 1/3 the price that you would expect to pay! The price of this limited stock item? - only $9.90 for the mains filter & varistor. 10 or more: $8.90 each. Oatley Electronics, PO Box 89, Oatley, 2223. Phone (02) 579 4985. ULTRASONIC BURGLAR ALARM kit. SILiCON CHIP, May 1988. A quality crystal-locked ultrasonic movement detector that doubles as a self-standing alarm. Has provision for bonnet/boot protection, flashing light and back-up battery operation . PCB & on-board parts only $27.90 (includes open transducers). Optional light flasher/ back-up battery parts $7.50. Alternatively, we can supply prewired ultrasonic transducers with mounting clips for $12 extra. That's incredible. Oatley Electronics, PO Box 89, Oatley, 2223. Phone (02) 579 4985. MASTER SLAVE SWITCH. Remotely switch your non-remote TV off & on via your remote-controlled VCR. Includes a mains filter & over-voltage protection. Can also be used with hifi systems, computer systems, etc. One switch operation will switch everything on! Only $32.95 for the PCB & all on-board components or $54.95 for the com- JuLY 1991 103 r "' MEMORY EXPANSION Prices at May 10th 1991 DRAM DIP ZIP SIMM & SIP SPEED Cns) TYPE 4164 41256 120 2.20 1.80 100 2.35 2.00 2.50 6.10 80 70 2.20 2.40 2.75 411000 7.30 7.90 1MB x 4 (Static) 38.00 20.50 21.00 22.50 256K X 9 62.00 72.00 81.00 1MBx9 295.00 4MBx9 SimmSockets30 X 1Vertical 1.70 Simm Sockets 30 x 2 Angle 3.50 Simm Sockets 30 x 2 Vertical 3.20 41464 '"PELHAM Altronics .............. .................. 86-87 CO-PROCESSORS INTEL 120.00 175.00 175.00 272.00 275.00 285.00 285.00 550.00 693.00 848.00 432.00 510.00 8087 8087-1 8087-2 80287-8 80287-10 287XLT 287XL 387DX20 387DX25 387DX33 387SX16 387SX20 CYRIX IIT Antique Radio Restorations ..... 104 Av-Com ............ .......................... 20 Back Issues .. .... ..... .... .. ........ , 78,79 178.00 David Reid Electronics ......... IFC, 1 Dick Smith Electronics .......... 11-13 510.00 640.00 780.00 406.00 440.00 480.00 600.00 670.00 395.00 Sales Tax 20%. Overnight Delivery. Credit Cards Welcome 1st Floor, 100 Yarrara Road, Pennant Hills, N.S.W. 2120 Tel(02)980-6988 Advertising Index Fax(02)980-6991 ,.. Electronic Solutions ................... 23 Electronic Toy Services ........... 104 . Elmeasco ................. .............. .... 77 Geoff Wood Electronics ............. 83 Harbuch Electronics .................. 61 Hycal Instruments .................... 104 Jaycar Electronics ................ 49-56 MODEL TRAIN CONTROLLER project, SILICON CHIP, November 1990, $19.95 plus $2.50 p&p. Plugpack, 12VAC, 1. 7A, suitable for the above (use rectifier), $29.95 plus $4.00 p&p. Kits built & repaired. Prototype production board supplier to the hobbyist & supplier of SILICO~ CHIP project PCBs. ETS, PO BOX 491, NOARLUNGA CENTRE, SA 5168. Phone: (08) 382 8919 FIX-A-KIT $20.00 PER HOUR LABOUR 3 MONTHS WARRANTY ON REPAIRS 12 MONTHS WARRANTY ON CONSTRUCTION Service to most typ e s of electronic equipment TECHNICAL ASSISTANCE HYCAL ELECTRONICS Design, Manufacture & Re pair of Electronic Equipm e nt Trading Hours 8am to 3pm, Monday to Friday (02) 633 5477 J.V. Tuners ............... .................. 47 Newtronics ........ ... ....... ........... ... . 16 Oatley Electronics .... ... ..... .. .... 5,89 PC Computers .............. ........ ... 104 PC Marketplace .. .. ...... .... ........... 9 Pelham ................... .. .......... ..... 104 Philips Test & Measurement .. OBC Raytec Data Systems ................ 61 RCS Radio .... ............................ 48 MAX 1/0 Board Kit $149.00. Built & Tested $269.00. • 7 x Relays SPST 2 amps each • 8 x Switch inputs (TTL) • 1 x DAC (Digital to Analog converter) ' 1 x ADC ( Analog to Digital converter) • 4 x Motor Drive outputs (40mA ea.) • 1 x Programmable timer output. MAX includes a 20·page manual with all schematics, parts layout elc., a 360K PC·compatible floppy with diagnostic and sample software in GW·Basic. MAX runs from a PC compatible printer port for full compatibility with a large range of computers. Same day dispatch of orders. Credit cards or personal cheques welcome. Phone (08) 332 6513 or Fax (08) 364 0902 (24 hours) PC Computers, 36 Regent St, Kensington; SA. plete kit. You'd expect to pay that much just for a mains filter with overload protection! Oatley Electronics, PO Box 89, Oatley, 2223. Phone (02) 579 4985. TRANSFORMER REWINDS ALL TYPES OF TRANSFORMER REWINDS TRANSFORMER REWINDS Rod Irving Electronics ....... ... 34,35 42,43,96,97 Reply Paid No.2, PO Box 438, Singleton, NSW 2330. Ph: (065) 761291. Fax: (065) 761003. Silicon Chip Binders .. ........ ...... IBC Stewart Electronics .................... 17 SATELLITE DISHES FOR SALE These dishes are the same as shown in 'Silicon Chip' June 1991 on page 14. 1.8 meter Aluminium. 44.8dB gain at 12 GHz $200.00 plus freight. 2.4 metre Extender kit. Lifts the gain to 46.97dB $200.00 plus freight. Phone (077) 411247 9am - 9 □ m 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 104 S rLICON CHIP Resurrection Radio ............ .. ...... 17 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. 1Oam-5pm; Sun. 12.30-5pm. 109 Cann St, Bass Hill, NSW 2197. Phone (02) 645 3173 BHor(02)7261613AH. SC Subscriptions ........................ 57,58 Telecom ..................................... 67 Transformer Rewinds .. ....... ..... 104 Videosat .......... ........................... 21 PC Boards Printed circuit boards for SILICON CHIP projects are made by: • Electronic 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. SILICON CHIP BINDERS NO * High quality * Holds up to 14 issues * 80mm internal wiilth * Gold printed with SILICON logo on spine and front cover CHIP - ·-_ ·-,:~ __;_;.~ These beautifully made binders will protect your copies of SILICON CHIP. We are especially pleased with their look and quality. As soon as the first batch came in, everybody on our staff wanted them to store their own personal issues. You will too. How To Phone (02) 979 5644 Fax (02) 979 6503 ORDER: ~ ,,,. .·-----~:;as-- . Made with a distililctive' two tone green high-quality vinyl specially selected for SILICON CHIP, and with heavy board covers, each binder holds a year's issues (the 14 issues of Vol. I or the 12 issues of Vol.2). They will look really smart on your bookshelf. To order your binders, fill in the coupon on age 58 and send it to SIILICON CHIP, PO Box 139, Collaroy Beach, NSW 2097. Alternatively phone (02) 979 5644 and quote your credit card details, or fax your orders to (02) 979 6503. Prke $All.95 plus $A3 each for postage and packing. (NZ postage and packing $Ao.)