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S3.50 DECEMBER 1989 NZ S4.95 ~C,_L- Contains pure compressed inert gas for deaning inaccessible areas on circuit boards etc 400ml $23 .35 National Miniature Relay Special Contact Cleaner/ Lubricant Remember those Matsushita Relays General purpose switch/contact cleaner for use where thin film of oil is required for penetrating and cleaning action. Non-flammable, safe on most metals, plastics and rubbers. 200ml $8.30 we advertised some time ago? ~ i5 Q:: 0 l<.. Cl 0 ~ ~ i5 Q:: a l<.. Cl 0 ~ We've lor.ated a fresh supply of SV versions of the double pole 2 coil latching type. 60W, 125VA rating. Will handle 240Vac, up to 2A switching. Measures only 20x10x9.3mm. 1500V surge rating. Fits standard IC socket DS2E-SL2-DC5V only $3.1111 each. Volume pricing for OEM's Fluke 80 Series ... Top of the line Multimeter The Fluke 80 series offers a huge range of extra features like a 200kHz frequency counter, -capacitance meter, combined analog and digital scales plus the ability to automatically record max/min and average readings and store them for up to 36 hours! Check the features and the value! 80 Serln Feltum • • • • l(: ~ Q:: 0 l<.. Cl 0 ~ 4 3/4 digit 4000 count resolution Digital Display updates 4 limes/s 87 has analog pointer 83/85 have analog bargraph with ~~°'!1te~':li\~~:isplay • 0.5Hz to 200kHz Counter with duty cycle from 0.1% to 99.9% e 10pf to 5f.iF Capacitance range • Input alert warns of incorrect connections • 87 is a true nns 1ms Peak Min Max hold meter with backlit display • Touch Hold and Relative modes 83 $418.80 ($372 11 tax) 85 $492.00 ($438 II tax) Clear Protective Lacquer Flexible coaling for printed circuits to protect against humidity and environment also provides eht sealing. Does not crack or discolour. Can solder through. 200ml $8.70 Gender Benders Adaptors etc Benders GB-9PJ9P DB9 plug to DB9 plug GB-9S19S DB9 socket to DB9 socket DB25 plug to DB25 plug GB-25P'25P GB-25S'25S DB25 socket to DB25 socket GB-36P/36P 36pin Centronics to 36pin Centronics Adaptors GB-9P'25S DB9 plug to 0B25 socket 0B9 socket to 0B25 plug GB-9S'25P Modem GB-25P'25S-NM NuU Modem 0B25 plug to 0B25 socket DCA-115 4pin modular DCA-116 6pin modular Spin modular DCA-117 Mtacellaneous All have 0825 Plug to 0825Socket GB-25P'25S-MT Mini Tester GB-25P'25S-SB Switch Box GB-25P'25S-PB Patch Box Mini Wiring Box GB-25P'25S-MWB CAS 1S-RS 23 2A CAS16-CENTRONICS Printer Switches RS232 A.B Switch Serial Printer Parallel Printer Switch Discount Disks 5 1/4 Bu1k Paca $6 .50 5 11'4 Flleule OS DO $18.50 ' 51/4 Fileule OS HO $34.95 31/2 Flleule OS OD $39.95 31/2 Flleale OS HO $69.95 All Prices per Pack of Ten Disks. $7.35 $7.35 $12.IS $12.IS $35.IS $8.15 $8.15 $13.IS $7.51 $I.SO $13.20 $21 .IS $11.IS $12.IS $11.15 $45.00 $55.00 Ribbon Cable Products We stock a huge range of flat cable assemb~es, extenders, gender benders. We can manufacture to your requirements. We also stock a comprehensive range of connectors. This month all 1.Sm extension leads for D89, 0B15 ind 0B25 are just 87 $576.00 ($525 11 tax) " - - - - - - - - - - - - - - - ' $11.IS H.P.A. Conformable Coating Protects circuit boards from environmental attack. Easily removed with nonnal safety solvents (e.g. Electrolube Cleaning Solvent) 200ml $15.60 Electronic Cleaning Solvent Fut non-toxic, non-flammable cleiner fQr use on deHcate electronic circuitry. No residue. Hannless to plastics and rubbers. 400ml $15.10 .,., a :l) .,., a :l) C") :t ~ .,., a :l) C") :t ~ .,., a :l) C") :t Printed Circuit Board Cleaner ~ IPA Electrowipes a A non-flammable blend of solvents to remove contaminants and flux etc after soldering. · 200ml $8.00 Lint-free and in Sachets. Impregnated with isopropanol and demineralised water. Ideal for cleaning connectors and removing oxidation etc during servicing. $D.IS EC8 Electruwip11 Similar to above but with electronic cleaning solvent $1.&S loltl Elecl,-i,a SimHar to above but specially fonnulated for gold, silver, palladium and other contact materials, connectors etc. $1.75 GEOFF WOOD ELECTRONICS PTY LT D 229 Burns Bay Road, (Corner Beatrice St.) iNc IN Nsw Lane Cove West, N.S.W. P.O. Box 671, Lane Cove N.S.W. 2066 Telephone: (02) 428 4111 Fax:(02)4285198. 8.30am to 5.00pm Monday to Friday, 8.30am to 12 noon Saturday. Mail Orders add $5.00to cover postal charges. Next day delivery in Sydney add $5.00. All prices INCLUDE sales tax. Tax exemption certificates accepted if line value exceeds $10.00. BANKCARD, MASTERCARD, VISA, CHEQUES OR CASH CHEERFULLY ACCEPTED .,., :l) C") :t ~ ~ a c:, .,., a :l) C") :t ~ DECEMBER 1 989 FEATURES 6 Install A Clock Card In Your Computer THIS DIGITAL VOICE board can be connected to a computer, used in a security system, or used to monitor various functions in ·your car. When triggered, it delivers one 'of four separate voice messages. See page 24. by Leo Simpson Plug-in card comes with full instructions 82 The Evolution Of Electric Railways by Bryan Maher Pt.26: the Pilbara iron ore railways (2) 112 The LM831 Low Voltage Audio Amplifier by D. Yates New dual audio amplifier chip from National Semiconductor 118 Index To Volume 2: Jan-Dec 1989 by Greg Swain Use this handy reference to track down articles PROJECTS TO BUILD 24 Digital Voice Recorder Board by John Clarke Versatile unit stores up to four separate voice messages PREVIOUS UHF REMOTE switches have been tricky to build but not this one. The transmitter is supplied readymade so all you have to do is assemble the receiver. Details page 46. 46 Easy To Build UHF Remote Switch by Greg Swain Features a ready made transmitter 74 Balanced Input/Output Stages by John Clarke Add them to the Studio Series equalisers SPECIAL COLUMNS 8 Vintage Radio by John Hill Scrounging bits and pieces 12 Remote Control by Bob Young Operating an R/C transmitter 34 Serviceman's Log by the TV serviceman Knowing when to draw the line 70 Computer Bits by Jennifer Bonnitcha Adding RAM to your computer 92 Amateur Radio by Garry Cratt Simple HF receiver for the 40-metre band NO,THE SERVICEMAN didn't ~) hit it with a hammer ~ although he probably felt like it. Why? See page 34. 98 The Way I See It by Neville Williams Broadcast television: an industry that's not sure where it's going DEPARTMENTS 2 Publisher's Letter 3 Mailbag 4 Subscription Page 21 Circuit Notebook 69 Back Issues 80 Silicon Chip Binders 81 Bookshelf 105 Product Showcase 116 Ask Silicon Chip 120 Market Centre WHAT - NO CLOCK card in your computer? This low-cost unit will fix that problem. Turn to page 6. DECEMBER 1989 1 SILICON CHIP Publisher & Editor-in-Chief Leo Simpson , B.Bus. Editor Greg Swain, B.Sc.(Hons.) Technical Staff John Clarke , B.E.(Elec.) Robert Flynn Advertising Manager Paul Buchtmann (02) 982 9553 Regular Contributors Neville Williams, FIREE, VK2XV Bryan Maher, M.E. B.Sc. Jim Yalden, VK2YGY Garry Cratt, VK2YBX Jim Lawler, MTETIA John Hill Jennifer Bonnitcha, B.A. Photography Bob Donaldson Editorial Advisory Panel Philip Watson , MIREE , VK2ZPW Norman Marks Steve Payor, B.Sc. , B.E. SILICON CHIP is published 1 2 times a year by Silicon Chip Publications Pty Ltd. All material copyright (c). No part of the contents of this publication may be reproduced without prior written consent of the publisher. Kitset suppliers may not photostat articles without written permission of the publisher. Typesetting/makeup: Magazine Printers Pty Ltd, Rozelle , NSW 2039. Printing: Macquarie Publications Pty Ltd, Dubbo , NSW 2830. Distribution: Network Distribution Company. Subscription rates: currently $42 per year (12 issues) inside 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. Address all mail to: Silicon Chip Publications Pty Ltd, PO Box 139, Collaroy Beach , NSW 2097. Phone (02) 982 3935. Fax (02) 982 9553. ISSN 1 030-2662 2 SILICON CHIP PUBLISHER'S LE't·tER Dynamic RAMs are getting bigger & cheaper Welcome to the December 1989 issue of SILICON CHIP. What do think of the cover photo on this issue? It is intended to be whimsical while highlighting the great strides that are being made in the production of random access memory for personal computers. The unit pictured in the girl's hands is actually a normal sized 18-pin chip which we have blown up somewhat to emphasise its enormous capacity which is 4 megabits. Made by Fujitsu, it is the latest dynamic RAM to use that company's 3-dimensional "stacked capacitor cell" (3D STC) which is crucial to achieving really large capacity. Now I don't know about you but I find dynamic RAM chips about as exciting as a pile of dead batteries. They don't have a lot of charisma do they? Even a really significant development such as a 4 megabit DRAM fails to grab me. Yes, I know that 4 megabits is a humongous amount of storage and it uses extremely fast refresh times (56ns) and ultra tiny chip geometry. Nevertheless, I have to acknowledge that without the developments of the last few years in RAM technology, our computers would be a lot more expensive, a lot slower and a whole lot less capable. And memory chips would be very expensive. Two articles this month actually emphasise how cheap memory chips have become. The first is a project which should interest many readers, even if they have not the slightest interest in computers. The digital voice board does not use a computer but does use 4256 memory chips which are now, well, as cheap as chips, considering their capacity. It will have many applications which will have little to do with computers. The second article related to DRAMs is Jennifer Bonnitcha's "Computer Bits" column which is devoted this month to adding more memory to your computer. If you want more memory, now is a good time to add it because memory chips are presently pretty cheap. But if you are turned off by our apparent emphasis on memory chips have no fear. We won't let them take over the magazine. We will continue to present articles to appeal to the widest possible readership. On the other hand, since dynamic RAM chips are being made in such huge numbers and in such huge capacities, we can hardly ignore them, can we? And since it will shortly be the festive season, I and the staff of SILICON CHIP magazine wish you a happy and safe Christmas. Thank you for your support over the last two years. You can look forward to even bigger things from SILICON CHIP next year. Leo Simpson MAILBAG Semi trailers as rail freight On page 105 of your September 1989 issue, in the article on electric railways, there was a photo of semitrailers being railed. I took the liberty of sending the photo to the Minister for Transport and received the attached comment. You may wish to publish it for reader interest. Bill Jolly Nambucca Heads The letter from State Rail The Minister has asked me to reply to your recent letter concerning rail freight transport. State Rail is continually on the lookout for new modes of transporting freight on both intrastate and interstate corridors. The mode shown in your letter has been investigated many times and has been found to be unsuitable for rail corridors within NSW. This is because of the height and width restrictions within electrified areas of the state and the tunnels through the Great Dividing Range. This type of traffic is currently operated between Perth and Adelaide. However, its use has proven to be limited and containerisation is favoured as the most suitable intermodal (road and rail) system to suit our environment. Lucio Di Bartolomeo General Manager Express Rail, NSW Making your electric radiator safe I refer to your article "Making your Electric Radiator Safe". In general I can only applaud the advice given therein although I query any brass pin being too thin to carry 10A, even SILICON CHIP, PO Box 139 Collaroy Beach 2097. though the English 13A plug is so enormous. However, I believe that you should carry an addendum to the advice given to the effect that the pins of such plugs should be kept clean and bright. I have encountered severe overheating where the brass is corroded. The same applies to the contacts in the GPO. Though I find SILICON CHIP to be interesting and informative in matters electronic, I must admit that I resent the excessive area given to cartoons. I also query the inclusion of railway construction matters in an electronics magazine. W. Chidzey Sandringham, Vic Electricity tariffs After reading the Publisher's Letter in the September issue, I felt compelled to write to you on the question of tariffs for electrical energy. The The latest stereo receiver on the market today! Features: Dolby* and Hall surround sound for your pleasure; a protection circuit to prevent damage to your receiver for your peace of mind; precise digital synthesized tuning for accurate radio reception; 30-station memory preset and scan function for ease of operation; audio and video dubbing function for integration of all your audio/video equipment; alphanumeric display that shows the status of your musical world at a glance and infra-red remote control for your total convenience and it's backed by the largest electronics store in Australia. Who makes it? SUBSCRIBE SUBSCRIBE SUBSCRIBE Have SILICON CHIP delivered direct to your door at no additional cost. Each month, we '11 bring you the best and brightest electronics magazine, put together by Australia's most experienced team. • • • • • • .. J fi Police radar: it's not always right · \j Intelligent charger for 12V gel batteries CONSTRUCTIONAL PROJECTS AMATEUR RADIO VINTAGE RADIO COMPUTER BITS THE WAY I SEE IT INFORMATIVE ELECTRONIC STORIES ~----------~------------------------FREEPOST* 24 Hour Fax Service (02) 982 9553 Send the coupon with your Credit Card details. 24 Hours, 7 Days a week. SUBSCRIPTION COUPON D Renewal D New subscription Start in Name Subscription Hotline Telephone (02) 982 3935 9am-5pm Mon-Fri and quote your Bankcard, Visa Card or MasterCard No. and expiry date. (PLEASE PRINT) Street Suburb/town Postcode 1 year (12 issues) D $A42 2 years (24 issues) D $A84 NZ & PNG (airmail) D $A65 D $A130 Overseas surface mail D $A62 D $A120 D $A130 D $A240 Australia Detach Coupon and Mail to: FREEPOST 25 SILICON CHIP PUBLICATIONS PO BOX 139 COLLAROY BEACH NSW 2097 *No postage stamp required in Australia. 4 SILICON CHIP Overseas airmail Enclosed is my cheque/money order for $ _ _ _ or please debit my D Bankcard Card No . I D Visa Card I I I I I i D MasterCard I I I I I I I I I ~ I Signature _ _ _ _ _ _ _ _ _ Card expiry date_ _ / __ /_ _ ~ L-----------~-----------J first statements you make are quite in order but the statements you make in your last two paragraphs leave me astounded. As I have always understood it, coal fired power stations with their immense boilers and turbines cannot just be turned off at 10 o'clock at night (or thereabouts) when most offices are closed, the trains stop running and factories shut down. Nor can they be turned on again by the flick of a switch at 6am. If you did away with all hot water systems no energy would be saved because of the hours needed to shut down and restart the boilers. People might as well be encouraged to use this surplus energy and therefore provide some extra revenue rather than let it go to waste. Please in future make more realistic statements on energy conservation as you did earlier in the piece. H. Jenner Attwood, Vic Comment: we're well aware that alternators and boilers cannot be turn- ed off at night. In fact, it takes as much as eight hours to run a large alternator up to full power from cold. However, there is a large difference between maintaining alternators and boilers on "spinning reserve" and supplying large amounts of off-peak puwer. The power generated is by no means free and it takes a large amount of coal to produce more than the spinning reserve. Wants projects for the Commodore C64 I am a newcomer to electronics and a regular reader of SILICON CHIP. I have noticed features and projects on computers but they are always for IBM or PC compatibles. What about the people out there with their old faithful Commodore 64s? I am a member of the Commodore Computer Club which has members like myself who are interested in both electronics and computers. So what about some projects and a circuit or two that would work well on the 64 or 128 that would otherwise be gathering dust? I really enjoy your magazine even though some of it is over my head. I have succeeded in making up some of your projects and hope that you can help me out. R Ch . apman Jandakot, WA Success with auto-zero module Thank you for publishing John Clarke's version of the Auto-Zero Module (SILICON CHIP, Sept. 1989). I have just mounted two of these modules on the rear of my modified Studio 200 amplifier (to replace the manual offset adjustment). In my version, the 330 resistor in the module was removed, installed end on in the vacated earth pad for the 22k0 resistor (in the amplifier module), and the other end joined to the top end of the 22k0 resistor. A small length of shielded cable was then run back to the Auto Zero Module from the junction of the 22k0 and 330 resistors and signal earth. A. Kethel Turramurra, NSW CIPTIMUS® The Optimus® STAV-3200 is brought to you exclusively by Tandy Electronics, the first name in electronic equipment. This new dimension in stereo hi-fi receivers is a unique unit that will be appreciated by people who know and enjoy fine music. Come in and experience the performance at your local Tandy store. Enjoy music with the realism of "live" sound all in the comfort of your home. 31.3020 . . ..... ..... . . .. . .... . ............ . . . ..... . 999.95 Install a clock card in your computer Most computers these days are supplied with a real time clock but older machines usually do not have one. You can remedy this situation easily by installing a clock card. You will then have time and date available at the touch of a key. By LEO SIMPSON There are many programs which require a real time clock and others which will make use of the clock facility if it is fitted. For example, if you are using Sidekick or Popcorn in your machine, the calendar function will always be correct if you have a clock card installed. If you have a program which keeps track of appointments or a diary, again you need a clock card to make it function properly. A clock card can also be useful when you consider that any file created under DOS will be labelled with the date and time. This can be very handy if you want to check when files were actually created or last updated. 6 SILICON CHIP Anyway, you get the picture - a clock card is a handy facility. And considering that you can have a clock card in your computer for just $50, why should you have to put up without it any longer? What's involved So what is involved in installing a clock card? To tell the story of what is involved, we obtained a sample card from Electronic Solutions. Their clock card comes in a standard "half card" size, ready to be plugged into one of the vacant slots in your IBM PC or compatible. The card is supplied packed in foam and accompanied with a small instruction book and a 5 ¼-inch floppy disc containing one program entitled "RTC-EXE". The card is apparently a multipurpose board as quite a few IC positions are vacant. In its clock card form, it has three 14-pin ICs, one 16-pin IC, one 20-pin IC and the main chip which is a 24-pin type. Also in evidence is a 4-way DIP switch, the clock crystal, marked "XTAL2", and the button-style 3V lithium battery. Before you install the card, you should remove the plastic sleeve from the positive terminal of the battery holder. If you don't do this, the clock will not run when the machine is turned off. Installing the card is simply a matter of removing the cover from your IBM PC XT or compatible, removing the expansion slot cover strip/retaining bracket from one of the vacant slot positions and then inserting the card. Push down firmly on the card to make sure it sits properly into its connector on the motherboard and then secure the retaining bracket with the single screw. As supplied, the DIP switch has all four switches in the ON position and it should not be necessary to touch these. You can now put the cover back on your machine. The next step is to turn on your machine and boot it up in DOS. You then put the clock disc into drive A, type in "RTC" and hit return. The program will then put a menu on the screen which gives you three options, numbered 1, 2 and 3. To set the time and date, you hit 3 and then it leads you through the steps of giving the day, month, year, hour, minutes and seconds. It will then say "Bye" and throw you back to the A) prompt. If you then type RTC again and hit 1, the machine will be initialised with the correct time and date values. If you then ask the machine for the Time (type 'time' and hit return), you will get the correct time. Similarly, if you ask for the Date (type 'date' and hit return), you will get the correct day and date, in the American format; eg, Mon 10-23-89. All these steps are detailed in the clock instructions. Making it automatic With the operation side confirm- THE PLASTIC SLEEVE MUST BE removed from the positive terminal of the battery holder before the clock card is installed. If you don't do this, the clock will not run when the machine is turned off. ed, you then need to make the whole process automatic by incorporating the clock program into your AUTOEXEC.BAT file on your normal boot disc or hard disc drive. You can do this by either modifying your existing AUTOEXEC.BAT file or by creating a new one. Either way, the instruction manual that comes with the clock card will tell you how to do it. So why wait? The clock card is available from Electronic Solutions, PO Box 426, Gladesville, NSW 2111. Phone (02} 906 6666. Fax (02) 906 5222. ~ THE CLOCK CARD IS INSTALLED in a vacant expansion slot on the computer's motherboard. Push it down firmly to ensure good contact, then secure the retaining bracket with the single screw. DECEMBER1989 7 VINTAGE RADIO By JOHN HILL Scrounging bits and pieces One problem confronting the newcomer to vintage radio is the apparent lack of replacement parts for old radio receivers. One way around this problem is to scrounge and repair secondhand parts. Although resistors, high voltage capacitors and some radio valves can still be bought from various sources, it is wise to stock up on as many secondhand parts as can be found. Wrecking derelict radios and scrounging usable parts has been mentioned before in this column and its importance cannot be overstressed. Many secondhand components are quite serviceable; often they are the only ones available. Early in my collecting career I went to considerable trouble to buy some of those hard-to-get high voltage electrolytic capacitors. These new capacitors have caused me a fair amount of trouble however, because most of them lack capacitance. I recently discovered that some of my cherished 16µF 500V electrolytics (which were being saved for replacements in my more valuable receivers) aren't much good. These capacitors are of South Korean manufacture and, on average, measure only 2-3µF. This simply means that they are not of much use. In many cases, far better capacitors were being removed than were being replaced. This experience has made me take another look at the alternative - old electrolytics of the secondhand variety. I know this subject has been touched on before but high voltage electrolytics can be quite a problem in valve radios and such problems need to be discussed in detail. At one stage I was all in favour of discarding old electrolytics but now I find that many of them are more serviceable than some of the new ones I have bought. Electrolytic capacitors vary greatly regarding their useful 1ife span. Some will still be working after 40 or more years, while others will not last half that time. Therefore, if old electrolytics are to be reused they must be thoroughly checked out first. In some cases, "repairs" will be required. There are a number of malfunctions that will put an old electrolytic out of action or considerably decrease its efficiency. These faults are: internal short circuits, internal disconnections, partial short circuits (high leakage) and drying out of the electrolyte. Simple checks These relatively new high-voltage electrolytic capacitors measured only about 3µF when tested for capacitance, so they were hardly a bargain. An alternative approach is to scrounge parts from sets that cannot be restored and from old b&w TV sets. 8 SILICON CHIP The first two problems are easily detected by using a multimeter set to the lkO scale. Short circuited capacitors will show full pointer deflection on the meter while an open circuit capacitor will show no movement at all. Such capacitors are instant candidates for the rubbish bin. condition and can be used. Incidentally, an analog type multimeter with a pointer is a more convenient instrument than a digital meter for checking electrolytics. Although it is possible for a digital meter to be used, a moving pointer gives an easily understood indication that can be seen at a glance. These capacitor tests require no accurate measurements. All that needs to be seen is the quick · response of the rising pointer followed by a drop off to zero or thereabouts. Test lead polarity All these components were salvaged from a black and white (valve type) TV set. Most of the capacitors are serviceable and have high voltage ratings just right for valve radio replacements. Other useful parts in a b&w TV set are valve sockets and high wattage resistors. Partially short circuited (high leakage) electrolytics can also be detected with a multimeter. Such capacitors will show up on the meter by a rapid rise in the pointer as the capacitor is charged by the meter battery. The pointer will then slowly slide back towards zero ohms, stopping somewhere between 100k0 and lMO, depending on the amount of electrical leakage in the capacitor. However, don't throw these capacitors away just yet. They may still be usable as we shall see later on. Finally, an electrolytic in good condition should behave in the following manner when tested with an ohmmeter. First, the pointer should rise quickly to about half scale deflection for a. 16µF capacitor. Once a state of full charge has been reached the pointer will then drop back to almost zero. Any electrolytic of 8-24µF that reads 5MO or more while in this charged state is in reasonably good An electrolytic capacitor in this condition can usually be salvaged by applying a coating of glue to the neoprene seal. Check the capacitor for capacitance and leakage before using it, as a faulty electro can cause big troubles. If you are using an analog multimeter to test electrolytics, connect the red meter lead to the negative end of the capacitor under test and the black meter lead to the positive end. This is most important. If one cares to check these meter leads with a voltmeter, the reason for this soon becomes apparent. You will find that the. positive meter lead (red) has a negative voltage on it and the negative lead (black) has a positive voltage, when in the ohms mode. The reverse applies to digital meters. In this case, you connect the red meter lead to the positive end of the capacitor and the black lead to the negative end. N~ let's get back to those electrolytics with a high leakage problem and see what can be done. Selleys "Kwik Grip" is a suitable glue for resealing suspect end seals. Provided they are carefully patched up and checked out, old electrolytics should give years of reliable service. DECEMBER 1989 9 If they're like this, throw them out! These old Ducon electrolytic capacitors are beyond repair and are typical of the units found in early valve radios. position, the capacitor can be considered perfectly reusable. On the other hand, if the voltmeter drops 20-30 volts or more, the capacitor has a leakage problem. However, in many cases, the meter pointer will slowly rise as the dielectric reforms and will usually keep doing so until it reaches the normal HT voltage. Some electrolytics respond to this treatment very well and a few minutes on the test rig quickly fixes any problems. Others require more time and will still have a bit of leakage afterwards, although it will be nowhere near as bad as it was before. On odd occasions an electrolytic is too far gone and the amount of electrical leakage is such that the capacitor heats up, which is a fair indication that things are not well inside. In these circumstances, continued application of HT will only make things worse and the capacitor should be discarded. By the way, always make sure that the capacitor is fully discharged before attempting to remove it from circuit or you could get a nasty shock. Don't just short-circuit the terminals though. Instead, discharge the capacitor through a tkn 5W resistor. Checking capacitance Many digital multimeters now include several capacitance ranges as a standard feature. Alternatively, you can buy a specialised capacitance meter if you are into serious restoration work. Electrolytics that pass too much current are possibly inefficient because they have been out of service for a prolonged period of time. Although such capacitors appear to be a bit sick, they often respond favourably to being connected to a DC supply for a short time. When given this treatment the oxide dielectric of the capacitor will usually reform, thus greatly reducing the leakage. Perhaps the easiest way to put a DC potential on an old high-voltage electrolytic is to temporarily connect it across the high tension supp10 SILICON CHIP ly of a radio in good working condition - but take care because 250 volts DC can deliver a very potent electrical shock. I have an old radiogram chassis on my work bench which serves this purpose quite well. It is interesting to note the behaviour of a voltmeter connected across the high tension when an old electrolytic is placed into the circuit. It will give a very good indication of capacitor condition. If the pointer falls slightly (about 5-10 volts) when the electrolytic is put on test, then rises to its original If old electrolytics are to be put back into service they should also be checked for capacitance at some stage of the proceedings. This can be easily done on a multimeter that has a capacitance range. A capacitance check should be made prior to the HT treatment described above. There is no better way to wreck a perfectly good multimeter than to check the capacitance of a charged capacitor particularly a high voltage electrolytic. Sealing the ends Anyone familiar with old electrolytics will have no doubt noticed that a good many of them deteriorate at the seal end. Deterioration can take the form of cracking in older electros or a blister-like bulge in more recent types. Quite often such a capacitor will still be in good working order BIT INTERFACE PRODUCTS SWITCH ON TODAY'S COMMUNICATION SYSTEMS PHAXswitch The BIT PHAXswitch is able to automatically distinguish between fax transmissions and standard telephone calls. Avoid the cost of second line installation. Telecom Approved . $328.00 (RRP) PEPs (Printer Enhancement Products) These old electrolytic capacitors were scrounged from various sources. A fair percentage of them will check out OK and can be pressed into service but it is a good idea to reform the oxide dielectric first by connecting them across a DC supply. but once the seal breaks down, it's not long before the capacitor dries out and gives trouble. The seal at the positive end of an electrolytic gives plenty of warning that it will eventually fail. Cracks or blistering will start to show years before the final breakdown of the capacitor. Therefore a little bit of preventive maintenance can greatly extend the life of such a capacitor. The neoprene or fibre seal can be substantially reinforced with a generous application of a suitable glue. Selleys "Quickgrip" appears to be ideal for this job and several coats on the seal will prevent further trouble. In fact, this treatment can extend the life of a doubtful electrolytic by many years. Other capacitors Valve radios also use a considerable number of high voltage capacitors apart from the electrolytics just discussed. These smaller paper ca_pacitors usually range from around .002µF to 0.5µF. Once again, suitable replacements can be scrounged. When one considers the price of new high voltage capacitors, this procedure is not such a bad idea. At the time of writing, a 0.1 µF 630V capacitor can cost between $1 and $1.50. Such prices can make the cost of a radio restoration a bit more expensive than it need be. Old black and white TVs (valve types) are an excellent supply source of modern polyester high voltage capacitors. These obsolete receivers can often be picked up for nothing, yet they contain handfuls of usable components - mainly capacitors, resistors and the odd electrolytic. Although old b&w television sets and other discarded electronic equipment may be a good source of usable spares, every secondhand component must be thoroughly inspected before it is installed in some other piece of equipment. A faulty capacitor can cause a good deal of trouble in a vintage radio. In practice, about 99% of parts check out OK and are quite serviceable - but they must be checked! In conclusion, there are heaps of usable spares for the taking if one is prepared to spend a little time and effort chasing them up. If money is a problem with your restoration work, then try scrounging a few secondhand parts on the cheap. By using carefully selected secondhand components, you can considerably reduce the cost of vintage radio restoration. ~ The total answer to printer sharing whatever the size of your system . BIT PEPs can be used individually or in combination according to your needs. Their intelligence also allows for more complex installation for printer sharing, switching and buffering tasks. From $199.00 (RRP) BIT BLITZERs Bit Blitzer modems. The NO COMPROMISE, NO ALTERNATIVE, FULL FEATURED means of quality communication interface. Telecom Approved. From $230.00 (RRP) Contact Banksia for your nearest retail distributor. BANKSIA INFORMATION TECHNOLOGY (AUSTRALIA) PTY LTD 205/83 Longueville Rd, Lane Cove, NSW 2066. Telephone (02) 418 6033 Fax (02) 428 5460. DECEMBER 1989 11 REMOTE CONTROL By BOB YOUNG Operating an R/C transmitter There are many considerations that go into operating a modern radio control transmitter and we will examine some of these in a practical way. In particular, we will have a look at how the antenna radiates the signal and how this can affect the control of your model. To begin with, the prime factor is transmitter output. The considerations involved in this one aspect of R/C design are numerous and cause most of the spurious service calls and practical problems encountered in operating on a busy club field. This entire column will be devoted to this one aspect, although the solo operator does not encounter many of these difficulties. The circuit designer is well aware that, as the popularity of the sport grows, the number of people using flying fields and boating/car sites is increasing. Because each site can only support a given number of users, it is important ·that the minimum output power needed for operational safety and reliability be used. This allows more fields to be operated within any given city. Two hundred watt linears are definitely out in the model business. Unwanted interference is not merely annoying - it can have lethal results. A model travelling at 160km/h can kill. Besides that, government regulations on the use of R/C equipment limit the power to 2 watts total DC input with a maximum EIRP (effective isotropic radiated power) of + 30dBm (1 watt). Most modern systems use less than this, with 500-600 milliwatts being typical. This will give out of sight range on a model aircraft. At this power, fields can be as close as 5km apart. In Australia, we are allowed to operate on the frequencies 29.72 to 30.00MHz, 36.00 to 36.60MHz, and 40.66 to 40.70MHz. The 36MHz band is limited to competition type aircraft and watercraft only (Dept. of Transport and Communications Fig.1: the radiation pattern from an antenna is not symmetrical but has a number of lobes instead. The signal is weakest at the antenna tip so don't point the antenna at the model - it could crash! 12 SILICON CHIP DOC 60 and DOC 303, 1988). All other frequencies are illegal for radio control of models. Reduced range One very interesting and important point to keep in mind when operating models, particularly aircraft, is that the range is reduced as the Rx (receiver) antenna is brought closer to the ground and this effect is even more noticeable as the frequency is increased. The effect is worsened by the "lobes" of the transmitter antenna whereby, when the antenna is vertical, the signal strength radiated from it varies quite dramatically according to direction. Fig.1 shows the transmission lobes for a typical antenna and as you can see from this, the signal is weak at points A and B, and directly along the ground. Thus, flying low a long way out is not recommended. When range checking your model, be sure that the Rx antenna is the same height above the ground each day. When the Rx antenna is within 1 metre of the ground, the range is very badly affected and great changes in range will occur for every 15cm change in height. The moisture content of the ground also plays some part and results can differ from day to day as a result. Changing receivers from model to model will often also give differing results when range checking. The reason is often simply that the Rx antenna in one model is closer to the ground than in the other. Don't point the antenna Another important consideration that designers and flyers must take This Christmas at David Reid Electronics 127 York Street SYDNEY 2000 Ph: (02) 267 1385 MAIL ORDERS P.O. BOX 0103 SYDNEY 2000 FAX: (02) 261 8905 David Reid Electronics POST & PACK $5-$25 .... $4 $26-$50 ... $5 $51+ . . . .. $8 BUSINESS HOURS Mon-Fri B.30-5.30 Thur 8.30-7 .00 Sat 9.00-1.00 avoid pointing the Tx antenna at the model, placing the Rx antenna in close proximity to battery and servo leads, or flying low a long way out. Car enthusiasts beware Unless you take precautions, the antennas on adjacent transmitters can absorb or reflect your signal, leading to momentary loss of control. There's over 50 cars on the starting grid here so there's plenty of potential interference problems. If an unwanted signal is very close, it can swamp the front end tuned circuits in your model. into account is that the transmission lobe from the Tx antenna is theoretically donut shaped. This means that the signal is the weakest at the tip of the antenna. Thus, flying low and pointing the antenna at the model is definitely taboo. It can lead to a momentary loss of signal with serious consequences for the model. This condition is aggravated by 14 SILICON CHIP the fact that the transmission pattern is not a perfect donut. It is instead quite jagged in shape, resulting in weak signal areas in the most unexpected places. All of this must be taken into account by the system designer when setting the parameters for Rx sensitivity and Tx output power. So the flyer should keep in mind the possible dangers. He should Still on the problems associated with transmission patterns and levels, there is a special problem for the R/C car enthusiast. The average model car meeting always looks to me like an old Errol Flynn movie. There are 10 to 20 drivers, all waving their transmitters around excitedly, with frequent clashes of antennas. Add to this the fact that the track is usually in close proximity to the drivers and you have a recipe for trouble. What model car enthusiasts must realise is that other transmitter antennas act like reflectors and directors. This means that other antennas near your transmitter's antenna can absorb or reflect your signal. Thus, each adjacent antenna reflects some power away from the line of radiation. As well, the tuned circuit at the base of the other antennas will absorb some power, as is illustrated readily by placing another Tx, fitted with an output power meter, in close proximity. Its meter will show a reading, even though the Tx is switched off. The end result of all of this is that when a car comes into the straight and the driver of that car is at the far end of the queue, with many transmitters between him and his car, the signal is probably at its weakest point. Add to this a sudden savage increase in radiated power from much closer transmitters falling on the Rx antenna, servo leads, battery leads and circuit board lands, and the stage is again set for glitches (momentary loss of control). Great care must be exercised if you want to win races consistently. It is surprising how many complaints I receive from drivers who feel their receivers are out of tune or worse still, that other transmitters are off frequency. Once I point out these simple facts their problems often go away. There are of course always genuine Developed by the author, this 16-channel transmitter can control a range of functions on a model truck, including steering, brakes and gear change. cases of interference but they are rare. Another common problem here is the positioning of the Rx antenna in the car and this will be dealt with later. Designers of radio control systems have their special problems and the foregoing is one of them. If an unwanted signal is very close and very strong, it can swamp the front end tuned circuits in the Rx, The effect is similar to that which you experience when your hifi system is subjected to a CB'er driv- ing past your front door. The music is drowned out in a burst of voice transmission. This problem is not to be confused with an Rx bandwidth problem (ie, the ability of an Rx to reject signals close to the Tx frequency), although this does play some part in the problem. The bandwidth problem will be discussed in a later column. It is primarily an artificial problem, caused by the close proximity of many transmitters. Most of the problem probably comes from the base of the audio or IF (intermediate frequency) transistors rectifying the RF signal present on the circuit board tracks and demodulating it. I noticed that the problem got much worse after the change from metal Rx cases to plastic. I have even encountered situations where, after removing the Rx crystal from lts socket, the Rx could still be operated at close range. Some particularly bad cases will operate with power applied to the audio stage only. When you are on the end of the Radio-Controlled Motorbike from Dick Smith Electronics / Ii Currently available from Dick Smith Electronics, this radio controlled motorbike is typical of the diversity of models that are available. The transmitter (above) is a 2-channel proportional unit giving control of steering and motor speed. It is priced at $199 (Cat. Y-2541) from all Dick Smith Electronics stores. DECEMBER 1989 15 ...-------------------'l,,,,,,.---4,________,__.,..__..... ~-+9.6V .,.. r ---, TEST I I INPUT n--➔-----41._,__,..__ _ __.,..__--4..,___,..___..,_____...,__..,__ __._---4.,___---4~--~--+--,.__---0METER- fig.2: this circuit is typical of transmitters in use today. Note how the meter and associated diode is fed via a capacitor from the antenna. That explains how you can read the power absorbed by your antenna from other transmitters when your transmitter is switched off. queue therefore, you are really up against it, so please be careful. The same applies to aircraft taxiing in the pit area or landing or taking off in close proximity to other transmitters. The answer to this problem is really simple. Do not set your field up in such a way that models come within 7 metres of any Tx. Avoiding a crash Finally, the most dangerous situation of all is when two transmitters operating on the one flying field are separated by several hundred metres. Even though they may be on separate frequencies, if one model flies close by the other Tx, the disparity of signal levels can be so great that the Rx in the model cannot function properly. The most likely outcome is a crash. This is a situation which should never be allowed to exist on any model flying field. It is most often encountered on fields mixing power models and gliders using bungee and winch launches. Thus we can see that quite apart from battery consumption and government regulations, there are many considerations that go into just how much power should be fed into a radio control transmitter. Excess power is just a nuisance. Before leaving the Tx output stage, let me give a few practical tips. Do not run your Tx for extended pertods of time with the Tx antenna collapsed as this will result in a large increase in current 16 SILICON CHIP Club meetings like this are becoming increasingly popular. If you want to win, keep your antenna clean and the rest of the gear in tip-top shape. in the output stage with subsequent overheating of the output transistor and possible failure. This is fairly common problem for the poor old serviceman. Antennas The antenna is also a very important item. Most telescopic antennas on modern R/C transmitters are just barely adequate for the job. Ideally, we should be using ¼-wave antennas but on the frequencies we are · using these would be up to 2.5 metres long and are just not practical. The circuit designer therefore uses base loading coils to artificially extend the length. Unfortunately, telescopic anten- nas are quite flimsy and it is easy to loose one or more sections of the antenna. If this happens, the Tx will be very badly detuned and a noticeable loss of range can result. Do not fly with a damaged antenna. Likewise, always keep the joints clean and lubricated. CRC 2.26 is ideal for this job. I am always amazed at how much dirt comes out of those joints. I don't know how some transmitters that I see keep going. As you can see, the Tx RF section is quite a vital section of your R/C system. Learn how to use it, look after it and you will be rewarded with models that live a long and comfortable life. See you next month. ~ UITAR SPEAKERS 10" 65 watts Cat. CG-237 $59.50 12" 100 watts Cat. CG- $89.50 5" 150WRMS 80mm dia. Voice coil. · Cal CG-2382 Only$ 1.5V BAffERY TESTERS The latest in battery testers. Consists of a very flexible piece of plastic with a conductive strip on the rear. Simply place over tha battery terminals and the indicator will show if the battery is good, reasonable or bad. Re-useable. Every desk drawer. workshop, toolbox needs at least one. And at the price • who cares. 5 different designs available. ONLY 65~ EACH OR4FOR$2 :,11L. " Cat SB-2350 Merry Christmas PENLIGHT NiCads SAVE EVEN MORE SOOmA/Hr Cal SB-2452 . ~·.. · This amplifier was originally supplied with a pair of 5 watt walkman speakers. We believe this amplifier has much more merit on it's l7Wn rather than accompanied with two , ,r;· .~ . very ordinary _speakers. which effecttVely doubles the price. $11 . The amphfer Is battery operated (requires 4 x AA) or can be \; . used with a DC fN external source. Its input and output connections are VJa 3.5mm stereo sockets. One for in, one for out It has 3 leds for each channel to monitor output, a • high pass and low pass filter switch and an on/off switch with LED indicator. Size 150 Lx70 D x 225H mm. Ideal for Ideal for cars, homes, etc. Sticks to walkmans, or anywhere a ICM/ pO'Nlll' battery operated inside of window. Size 72 x 32mm. amplifier is required. Cal LA-5100 SPECIACATIONS 0.5 watt per channel 8 ohms Normally 95~ ea ~:u~ Imp 600 ohm 120 H2 • 20 Kh2 -3dB Band Width Voltage Gain 8 dB+/· 1 dB (walkman only) Input voltage 250 nw + pO'Nlll' output 30 (walkman) Was $3.50 ea NOW $3 EA or See Silicon Chip Nov '89 4 Ideal for students, who can now build something really useful. Multimeter specs: 20,000 ohms/Volt. 23 ranges, continuity buzzer. Size 135 x9Jx 40 Cat KC-5058 ONLY $34.95 3 IN 1 ALARM CHRONOGRAPH Incorporates • Hand held stop watch • Clip stop watch • Alarm chronograph wrist watch• Whistle Features • Quartz security • 1/100 second chronograph with I apse time • Display hours, minute, se:onds, month, date and day flag • Alarm and hourly chime function • Battery included CalXC-0200 for ~ ~ MINI STEREO AMPLIFIER .. ~ -· · •· . ~~ .· .,,."I!. · ALARM STICKER NOW 3 FOR $2 ONLY $9.95 RECTIFIER DIODE MADNESS 1N 4003 1 AMP YXfv Cal ZR-1003 1N 4007 1 AMP 1000V Cat. ZR-1009 $2.50 for50 $5.00 for50 ~ MACHINED AIRCRAFT GRADE ALUMINIUM FLASHLIGHT What an excellent product! It measures 145mm long and runs off 2 x AA batteries. It is 70 times brighter than a normal torch and the beam Is ad1ustable from spot to beam. and it's waterproof and shockproof. Durable anodised abrasion resistant finish, with a non shp knurled gnp. It can also be used as a lantern. Unscrew the top and the bulb is exposed to give 360° light. A spare bulb is supplted and mounts in the torch. We have seen these torches for $19. - WAS $9.95 SAVE $1 NOW $8.95 BUILD SOMETHING OVER THE BREAK }, STUDIO 200 HI-FI PREAMP High quality. Distortion below 005%. $2~~ Cat KC-5033 "SCREECHER" CAR HANDS FREE SPEAKER PHONE ALARM Thousands sold Cat KA-1675 $34.95 1/3 GRAPHIC EQUALIZER $239 ' • 32 band, high quality Cat KC-5050 MAWi:il!IP~ . . . . M C I ~ ~ . =~ -- , f ~ ~"' Ca< Kk1574 -~~-~---i'·-·-----~ ~~--=·----- -~.', - ' • ' <O(¼,~ ... _ _ ,, ,, ~, ,, ~ 30V 1A POWER SUPPLY • ""~a ... 0 ~ * .,.:R~->-::.::-~:: :_:._:~ -==--~-=~ STEREO 1/2 OCTAVE Graphic equalizer cat Kc-soss • , , e ~~ $89.50 • '""' ~- y . y_y- --8 CHANNEL AUDIO MIXER Cat KJ-6504 $595 * $89 $16.95 "' --·-~~y _________?!!_ ( DUAL TRACKING POWE •• SUPPLY •• Cat KA-1682 • $129.95 >12 : 23C>VOLT,INVERTER KIT $269 Pictured with optional desk console. Cat KJ-6505 $119 ~ ~ ? FUNCTION GENERATO Cat KC-5013 $299 Cat KA-1550 $89.50 ~ ) BRAND NEW ..5000" TYPE HI-FI AMPLIFIER UHFNHF INDOOR TV AMPLIFIER SPLITTERS REF: EA Dec '89, Jan ·oo Another distress stock purchase which saves you money. This time two TV amplifiers. UPro Series I" LT-3818 At loog last the 9 year old 5000 amp design has been totally redesigned to accommodate latest technology! This totally new design features the best of the old ETI 5000 features including: ■ Magnificent heatsink front panel ■ Rugged chassis bar 2 rack unit construction ■ Proven Hitachi Mosfet technology This unit has a boost of 70dB x 2. It has a 75ohm socket for input and two 75ohm outputs. It operates from 240/. Its UHF and VHF and its frequency range is 40 • 860MHz. We don't recommend this unit be used in hiph signal areas. BUT ALL ELSE IS NEWI The new pro Series I features two especially European made 225VA Toroidal Transformers feeding two separate power supplies, one for each channel. (The ETI 5000 had a common power supply for both channels). This massive bank of energy not only increases channel separation, but gives the amp an ENORMOUS LEAP in POWER HANDLING. (See specs.) Better Features. The Pro Series I not only kills the 5000 for perfomace. it has great features. For example, it has a chassis plug IEC 320 style mains inlet and a switched chassis IEC 24fN socket to power other mains equipment It also features signal clipping LED's 011 the cast front panel. This keep3 in mind the highly likely professional applications for this amp. Simpler to Build. You would think that this new amp would be harder to build than the straight forward 5000. Not so! The Pro Series I, intact, is far easier to build and actually has less signal distorting components than the 5000. What do you pay for this magic? Incredibly, we have managed to well withing sight of the old 5000 · only $100 more. That's right! You get all this for only $599!! INCREDIBLE. As usual, the Jaycar kit comes with fN8r'f conceivable part· nothing else to buy• and Ja-;tar quality as a boous! Normally $89 NOW ONLY $59.95 LT-3819 This unit has a 75/300ohm input and two 75/300 ohm outputs. Further splitters can then be used as this unit is designed to drive up to 8 • 10 TV points. It also has a channel 3, 4, 5A and FM switchable trap (-25dB) in case of cross modulation of 18dB x 2. catKA-1725 $599 Was $109 NOW $69.95 5VA P.C.B. Mount Transformer Bargain A 15-0-lSV tranny less than 1/2 the normal cost! The Ferguson equivalent to this now sells for around $20. This is what you get for 1/4 of that 24W AC to 30-15-0 !Ill 150mA and 3V<at> 150rr.A MANUFACTURERS! We have a large quantity of these. Buy in bulk and save! 1-9 $4.95 10-99 $4.50 100+ $3.95 INTRODUCTORY PRICE Power output (per channel, with both channels driven) Continuous: 140W RMS into 8 ohms 200N RMS into 4 ohms IHF pulse power. 190W RMS into 8 ohms 3'lfN,/ RMS into 4 ohms Harmonic distortion 0.005% at 100W RMS into 8 ohms 0.007% at 140W RMS into Bohms 0.008% at 200W RMS into 4 ohms Intermodulation distortion 0.004% at 100W RMS into 8 ohms {4:1 ratio of 50Hz and 7kHz) Frequency response 10Hz to lOOkHz (-3dB points) Signal to Noise More than lOOdB below rated output (unweighted) Sensitivity 0.83V RMS for 100W into 8 ohms Input impedance Approx 33k ohms Output slew rate More than 00v/us Greater than 50 Damping factor Overload indicator Activated if output distortion exceeds 0.05% JAYCAR • CONTINUING THE EXCELLENCE OF HI-FI WITH THIS SUPERB KIT Dimensions (excluding pins): 41W x 340 x 32H Cat MA-2622 5mm 7.5mm◊7.Smm ~ ~ lfV I Pinout & Voltage ConnectionsO ~ : O 5mm ~1 __J I 24°¥1NJ L1smm THE LATEST KITS KA-1717 Subwoofer Adaptor KA-1718 Auto Ni Cad charger KA-1719 NiCad discharger KA- 1720 RGBI to PAL er-coder KA-1722 Low cost mains filter KC-5050 1/3 Graphic equaliser KC-5051 CD compressor KC-5052 Touch lamp dimmer KC-5053 Extension touch dimmer KC-5054 Garbage bin reminder KC-5055 1/2 sterep graphic eq. KC-5056 FM radio/motorbike intercom Quality Disks at Silly Prices 24 HOUR CLOCK $29.95 Another Jaycar direct import Would you believe• computer disks with a llffilME $42.50 GUARANTEE for lass money than you have ever had to pay beforal 5 1/4' DSDD 48TPI DOUBLE SIDED $27.95 /DOUBLE DENSITY $39.95 Cat XC-4730 $18.95 $6.50 for 10 $239.00 3 1/2' MF20D 13STPI DOUBLE SIDED /DOUBLE DENSITY $49.50 Cat XC-4736 $32.95 $26.95 for 10 $14.95 5 1/4' DSHD 96TPI DOUBLE SIDED $24.95 /HIGH DENSITY Cat XC-4732 $349.00 $18.95 for 10 $69.95 All disks are supplied with envelope, Index labels and write-protect tabs. Remember, these disks might be cheap but they are good quality. We are so impressed by the quality we are happy to offer a lifetime guarantee. MOVEMENT Another addition to our range of clock movements. Ideal for Ham radio operators, astronomers, people in airlines and the weather industries, and the military. Make your own clock face. Includes 3 sets of plastic hands. Requires 1 x AA battery. Cat XC-0101 NfW ONLY $14.95 ARLEC TRANSFORMER BARGAINS ARLEC No. 61365 A chassis type tranny that gives 24CN to 24V CT C SOOmA and 'iN C 5A/ This tranny could give you a :1:12\1500mA and +Sil C SA DC power supply (with rectifiel3, regs. and electros of coul39i Caal. MA-2600 Normally$25 POWER CAR WINDOW WINDERS Convert your normal hand operated window winders to power windo.vs. It's really simple to connect remM! the manual handle, choose the correct adaptor and connect to motor drive and mount the drive unit Supplied with cables and auxiliary switch. Cat LR-8810 POWER WINDOWS FOR ONLY $219 Bargain of the century A. bargain at $9.91 10+ $8.95 P & P$4 extra ~\ ARLEC No. 81435 A grain oriented steel chassis type unit giving 24CN to <J.I AC <at>3A. 16V AC C 2A.16VACC1A. Thesecondariescan be wired to give 16V<at>3A or 24V C 3A. This is ideal for burglar alarm power supply as burglar alarms use 16V. You could also make a 13.BV regulated powei supply from this. Normally $30 - $35 ?:~vas••-91 Cat MA-2602 11 i~z'·~'""uJr i r_'• i, · · ~ ,,/· '/i ~j -~ A8i:f~~~traN o. 61~9 ·-•·,v) An_in-line "Maxibox· type power supply. 240V to 6V AC C 3 AMP. (Output lead fitted with 5.5 OD 22.1 10 DC plug.) Normally worth $40 _. ?t~Y95$9.91 Cat MA-2608 --r,,~ \\ \' MICROCHART SELLOUT For december you can grab the unique "Microchart· (see over for cat details) for never to be repeated prices. -· Cat BM-8501 BM-8502 Desc. 8080A,l80005 Data 6502/65XX Data BM-8503 BM-8504 BM-8510 BM-8516 54/74 TTL (LS) Data Algrithms Basic Intro Data 68000 Data Buy 4 bet the 5th FREEi! 100 assorted LED's including 3mm and 5mm in yellow, orange, red and green, rectangular-, triangular and other shapes and displays! All for less than ~ each! Cat.ZD-1696 $8.95 NORMALLY $9.95 NOW $6.95 ~ ~ DIGITAL CAPACITANCE METER NEW Anew addition to or range of test equipme Ideal for checking tolerances, measuring unmarked/ unreadable values, sortin values, selecting matched sets measuring cable, etc. 31/2 digit LCD display over Range Resolution 9 ranges. 200pF 0.1 pF Includes zaro 2nF lpF adjustment knob. 20nF l0pF Overload fuse 200nF l00pF protected. Three 2uF lnF months 20uF l0uF guarantee. 200uF lOOnF Specifications: 2,000uF luF 20,000u F 10u F Cat QM-1572 INTRODUCTORY PRICE ONLY $109.95 Scoop Purchase! 12 KEY NUMERIC PAD (telephone style) This fantastic little keypad measures 67H x 44W x 7D. Each button is separately addressable and has a fantastic tactile feel. 0-9 plus• & # keys. Connection data provided. Japanese made. Quality. Cat SK-0760 $2.50 each OR 5for $10 STILL AVAILABLE 480/50 50 watt module Cat. KE-4050 $27.50 480/100 100 watt module Cat. KE-4052 $34.50 POWER SUPPLY TO SUIT Cat. KE-4048 $29.50 TRANSFORMER Measures 280w x 145h x 170d Cat XC-3050 Not $99 $79 SAVE $20 TURN YOUR SURPLui ' STOCK INTO CASH! Jaycar will purthase your surplus stocks of components and equipment. CALL GARY JOHNSTON OR BRUCE ROUTLEY (02) 747 2022 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. High current intelligent charger In the July 1989 issue, Garry Cratt described an intelligent battery charger for small 12V gel batteries. It used a Unitrode UC3906 IC which controls both the output voltage and current to ensure optimum charging conditions. The original circuit could deliver up to 500mA of charging current but this can easily be increased to around 1A using the circuit shown here. In this circuit, the original MJE2955 pass transistor has been replaced by a BC328 (Ql) and this is then used to drive a 2N3055 power transistor (QZ). At the same time, resistor Rl has been increased from 0.50 to 4.70 to limit the maximum current to about 1A. DZ and the 5A fuse protect the circuit against reverse connection of the battery. The modified circuit also uses trimpots instead of 1 % resistors to set the output voltages. To aid set- Exhaust temperature alarm for boats 02 2N3055 01 1N4002 01 BC328 4.m + 20V -i 5 3 4 2 16 15 68k 12 10k IC1 UC3906 13 VR2 10k 20k 10 VR1 100k 8.2k .001 ... ting up, the over-charge indicate terminal (pin 9) is used here to drive Q3 which in turn drives LED 1. The setting up procedure is as follows: (1) centre both pots; (2) charge battery until LED 1 is on; (3) adjust VRZ for a float charge level of 13.6V; {4) Discharge battery slightly; (5) Recharge with LED off and adjust VRl so that LED turns on when the battery voltage reaches 14.5V. Bill Jolly, Nambucca Heads, NSW. ($25) 01 1N4002 -+----------------------, +12va-..... BATTERY If you own a boat, this circuit could save you the expense of a cooked motor. It's 12V PIEZ0 ALARM designed to detect an increase in exhaust temperature as can easily occur if the water pump fails or a plastic bag (or other rubbish) blocks the water inlet to the pump. The circuit uses an LM329 precision 6.9V reference, an LM355 temperature sensor (ICl), an LM311 comparator (IC2) and a BD140 transistor (Ql) to switch the alarm on or off. Trimpot VRl forms part of a voltage divider across the LM329 and sets the reference voltage on the non-inverting input of ICZ. It effectively sets the temperature at which the alarm operates. The in- .,. verting input is fed from the junction of a voltage divider consisting of a 4. 7k0 resistor and the LM335 temperature sensor {ICl). Normally, ICZ's output is high and Ql and the alarm are off. As the temperature increases, the voltage across ICl increases by 10mV/°C. When it reaches the reference voltage, pin 7 of IC2 switches low and Ql and the alarm turn on. To sense the exhaust temperature, the LM335 should be glued (Araldite is OK) to the inside of a metal tube which is then clamped to DECEMBER 1989 21 02 1N4004 100k 14 12 13 .001 IC1 LM183DN ST ART STOP EARTH 10 g + 22 25VW+ 11 .,. START Self cycle bilge pump control This simple circuit makes an ideal bilge pump controller on yachts and cabin cruisers. It's based on the National Semiconductor LM1830N fluid sensor (ICl) and uses three probes to detect the water level: START, STOP and EARTH. When the water reaches the START probe, the circuit activates the bilge pump which then operates until the STOP probe is cleared. The pump is then turned off and remains off until the water level reaches the the exhaust elbow, just after the water mixing point. Peter King, · Airlie Beach, Qld. ($30) El-cheapo buffer amplifier The problem with most audio signal generators is that their 6000 output impedance doesn't allow much voltage to be developed across low impedance loads; eg, 80. The circuit presented here is a unity-gain, wideband buffer amplifier. It uses an LM317 voltage regulator IC with a simple resistive pull-down to form a low distortion class-A amplifier. The internal circuit of the LM317 shows that it functions as a voltage follower, with the output voltage always 1.25V above the voltage at the ADJ pin. 22 SILICON CHIP STOP EARTH START probe again. Refer now to the circuit. In addition to the LM1830, it also uses a CMOS 4016 quad bilateral switch (IC2), a transistor (Ql) and a relay. Switch IC2a is always on and so the START probe is always connected to the probe input (pin 10) of ICl. The remaining CMOS switches (IC2b-IC2d) are controlled by the pin 12 output of ICl. When the bilge water reaches the bottom of the START probe, pin 12 of ICl switches high and IC2b-IC2d all turn on. IC2b switches the STOP probe in parallel with the START probe while IC2d turns on Ql. Ql in turn activates A fairly well regulated current of around 50µ,A flows out of the ADJ pin, and this is used to "jack up" the output voltage, using a lOOkO resistor. This resistor may need some adjustment to set the optimum quiescent DC output voltage: it should be adjusted for symmetrical clipping at full output. Of course, the DC output voltage can also be set using two resistors in the usual way. The output swing with no load is 10V p-p and the output impedance is less than .Orn at lkHz. Because of the simple resistive pull-down. the maximum output swing decreases with heavier loads and is around 5V p-p into 80. The following performance figures were measured with a 6000 source impedance and an 80 load: • Frequency response - dead flat to lOOkHz, - ldB at 250kHz, and - 4dB at 1MHz; C H~.:. ~L j_ the relay which then switches on the bilge pump. The bilge is now pumped until the water drops below the level of the STOP probe. At this point, pin 12 of ICl switches low again and IC2b & IC2d are switched off. This stops the bilge pump and switches the STOP probe out of circuit. The bilge pump now remains off until the water reaches the START probe again, at which point and the cycle is repeated. (Note: for further information on the LM1830N, refer to SILICON CHIP, September 1989). Peter King, Airlie Beach, Qld. ($20) LOAD ovo------<1>------.....,---0......, • Wideband output noise around lmV p-p or - 74dB below full output. The "A-weighted" noise is so low that measurement proved difficult (around - 90dB would be a reasonable guess). Distortion proved similarly difficult to measure. Connecting an AC millivoltmeter directly between the input and output pins showed that the maximum difference between input and output is less than .004 % at all levels below clipping. Because this is a class-A amp- lifier, the efficiency is quite low. The 1M317 should be mounted on a heatsink with a thermal resistance of 20°C/W or less. A second 1M317 could be used as a constant-current pull-down in place of the 120 power resistor. Steve Payor, Kogarah Bay, NSW. ($30) -----------1--11l Stereo FM microphone transmitter There have been lots of designs for FM wireless microphones but all have been mono units with only a short range. As well, most FM wireless microphones suffer from low audio quality. This stereo unit has been designed for professional use. It utilises the BA1404 Stereo FM Transmitter IC, as originally featured in the October 1988 issue of SILICON CHIP. Op amps IC1a and IC1 b amplify the low level signals from the microphones. The amplified outputs appear at pins 1 and 7 and are then fed to a stereo compressor stage. This uses an NE572 stereo cornpander (IC3) in the feedback loops of op amps IC1c and IC1d. Its job is to lift the wanted signal above the noise level of the transmitter stage. IC2a and IC2b buffer the compressor outputs and drive the stereo transmitter stage (IC4) via VR1 and VR2 which set the input levels. Trimmer capacitor VC1 allows the output frequency to be adjusted. Full constructional details for the stereo FM transmitter stage, including the winding data for 11 and 12, can be found in the October 1988 issue. Ideally, the signal should be received on a good quality FM receiver and then passed through an expander; eg, as shown on page 43 of the March 1989 issue of SILICON CHIP. This restores the original dynamic range and improves the signal-to-noise ratio. The total current consumption should be less than 20mA and so the circuit can be operated from a 9V battery. Darren Yates, French's Forest, NSW. ($30) .. ~H•· "'! N-t-~H•· . > + --+-'IM~I\--IHI- ~Nr--+-¥Nr-f•· : c:i DECEMBER1989 23 The Digital Voice Board can store four separate voice messages, each up to 30 seconds long. The message played back depends on which of four on-board comparators has been tripped. A Digital Voice Recorder Board Here is a complete digital voice recorder board. It can be connected to a computer, used in a security system, or used to monitor various functions in your car. When triggered, it can deliver up to four separate • voice messages. By JOHN CLARKE This project is not a voice synthesiser which puts out those cornysounding announcements from computers. No, this is a complete digital audio storage system based on a new chip from Texas Instruments. It can be used to record and play back any audio signal but it is mainly intended for voice messages. You can record messages using 24 SILICON CHIP your voice in exactly the same way as you would with a telephone answering machine. The resulting recording will not sound like a voice synthesiser; it will sound like you. While we have suggested that the Voice Board be used with cars, security systems or computers, we are sure that readers will use this project in a wide variety of applica- tions. For example, it could be very effective on a model railway layout whereby it could provide a variety of trackside sound effects, station voice announcements and so on. If used in a car, the Voice Board could warn about doors being ajar, high oil or water temperature and perhaps low fuel. In a security system, the Voice Board could point to sensors that have been breached, call for a periodic sensor check or ask for a response from a remote check point. The Voice Board could also be used to give specific instructions to operators of machinery in factories. You could also have a lot of fun with this device. You could connect it to the front and back doors of your home and have it announce or query visitors. Anyway, we are sure you will think up plenty of other applications. Technical features The Voice Board can record up to four messages and then play them back in response to signals from four on-board comparators. Any or all of the messages can be played back at any time, depending on the sequence of signals from the four comparators. Each voice message can be up to 30 seconds long. That's long enough for virtually any message you could want - you can almost tell your life story in 30 seconds. The key integrated circuit on the Voice Board is a new device from Texas Instruments, the TMS3477. Texas Instruments refer to it as a "single chip voice recording/ playback controller using Continuously Variable Slope Delta modulation" [CVSD). In simple terms, the TMS3477 converts an analog [audio) signal into 8-bit digital data which is stored in dynamic RAMs [random access memory). Then on command, it will convert the digital data back into audio signals for playback via an amplifier and loudspeaker. So the TMS3477 provides both analog to digital (A-to-D) conversion for the recording process and digital to analog conversion [D-to-A) for playback. Inside the TMS3477 is an oscillator to control the sampling process, the A-D and D-A converters, and a number of enabling pins to initiate the various func-tions. Like a lot of these special chips, the TMS3477 requires a few support chips to make it do its job. As well as a number of dynamic RAMs, it needs an op amp to amplify a signal from a microphone, an audio amplifier for the output signal, various comparators and gates to initiate playback, plus a number of transistors to tell the user what is happening. Sound quality vs. duration Essentially, there is a tradeoff between recording quality and recording length, just as there is in any other recording medium. If you PARTS LIST 1 PCB, code SC07111891, 220 x 138mm 1 PCB label 2 8-way PCB terminal blocks 6 PC-mounting click action switches 1 4-AA cell holder 1 battery snap to suit 1 8-way DIP switch 1 electret microphone 1 80 loudspeaker Semiconductors 1 TMS34 77NL voice recorder (IC?) 4 TMS4256-15NL 1 x 256K dynamic RAMs (IC1O-IC13) 1 LM339 quad comparator (IC1) 1 4030 quad XOR gate (IC2) 1 4011 quad NANO gate (IC3) 1 4017 decade counter (IC5) 1 40106, 7 4C14 hex Schmitt trigger (IC6) 1 7 4HC32 quad OR gate (IC4) 1 TL072 dual op amp (IC8) 1 LM386 audio amplifier (IC9) 2 7805 3-terminal 5V 1A regulators (REG1 ,2) 4 BC558 PNP transistors (Q1-Q4) 17 1N914, 1N4148 signal diodes (01-01 7) 3 1N4002 1A rectifier diodes (020,021 ,022) want long recording times, you have to sacrifice sound quality. If you want good sound quality, you get shorter recording times. In a digital recording system like the Voice Board presented here, the recording quality is set by the sampling rate. In the TMS3477, the sampling rate is set by the internal clock and by the programmable internal divider. The internal divider can be set for a nominal sampling rate [depending on the clock frequency) of 16kHz, 32kHz or 64kHz. Depending on how you select the clock frequency and the internal divider, the recording duration will be between 5 and 30 seconds. The Digital Voice Recorder Board measures 220 x 138mm and includes all the circuitry necessary to make it work apart from offboard components which are the DC power supply, an electret 2 1 6V 1W zener diodes (018,019) 5 5mm red LEDs (LED1-5) Capacitors 2 4 70µ,F 16VW PC electrolytic 2 100µ,F 16VW PC electrolytic 2 22µ,F 16VW PC electrolytic 4 1 Oµ,F 16VW PC electrolytic 3 1µF 16VW PC electrolytic 4 0.4 7 µ,F 16VW pigtail electrolytic 9 0.1 µ,F monolithic ceramic 1 .04 7 µ,F metallised polyester (greencap) 1 .004 7µF metallised polyester 1 .0022µ,F metallised polyester 1 1 OOpF ceramic 1 47pF ceramic Resistors (0.25W, 5%) 4 2 .2MO 1 39k0 1 1MO 1 27k0 1 680k0 1 22k0 1 270k0 7 1 OkO 9 220k0 5 4700 11 1 OOkO 1 1 000 2 47k0 3 100 5 200k0 miniature horizontal trimpots 2 1 OkO miniature horizontal trimpots Miscellaneous Tinned copper wire, solder, etc microphone and a small loudspeaker [OK, you can use a large loudspeaker if you like). The DC power supply can be between 9 and 12 volts and there are two separate power inputs on the board. One is for standby power to keep the recordings in memory and the second is the main input to fully power up the board. Standby current is 5mA and when fully powered up the circuit draws a minimum of 15mA and considerably more on playback and when the LEDs are lit. We have included an on-board battery for memory backup when external power is removed. Four sensor inputs There are four inputs which can be used to trigger the various voice messages. The four inputs are connected to four comparators and DECEMBER 1989 25 N -0 ::i:: - n ~ 0 n t: ~ Ol D101 ·' 1N414B S9 MEMORY CATCH ~ I +5V:.l STANDBY + .,. 22.I 220k ~ ,1 1N4148 D9 +5V_._....,___ __ POWER ~ IC6c ! TL072 I 47k 100P. 13G>o12 IC61 1M ~ -:- O.lI 141 CK 15jR . 13 J;_E IC5 4017 . 16 716 5.1 3'7 ,.z .,. J: ,RESET 012 1N4148 PLAY S12 •• .!!.!.. RECORD -i"i PAUSE S13 • STOP S14 47pFI 200k DSC IN .Ill . 14 .,. . 114 AP6 24 17 RAS AP8 26 AP7 25 AP 23 AP4 22 AP3 21 -:: T 3 .L o.1I ::;:: SPKR 1 VDD2 +5V POWER IC7 TMS3477 C/181 12 IC6d' S J!.ipa BIREC lOIPAUSE lllSTOP 6 h'P--4 rl I 5 28 VDOl ::DSCOUT lr 10k 017 1N4148 ! RESET,. SlO ICBb~I +5V POWER 680k 0.1t . - - - - - - - - - - - - - - - -STANDBY +5V I 5tSos 74C14, 40106 -:- T + +5V POWER lOOpF +5V STANDBY I .00471! 27k~ 270k .0022 +5V POWER .047:t 0.1'+ 51 AO ~ 16 IC10 4256 MEMORY 1 +5V STANDBY +5V STANDBY .,. o.1I MEMORY IC11 4256 2 MEMORY 3 IC12 4256 MEMORY 4 IC13 4256 +5V STANDBY 0.1! STANDBY -: .~)o_ .----4..______,___________________......,_+5V 0.1 I BP. ..;J ~ t:lj I ::~ I tl:l ~ t:lj (") t, t:lj t) I Wit 1 OUT I 1 OUT ~ + •t ♦• T 2.2M ? I T 100k ' T J:I 3 + 1 0 T INPUT 4 T I 100k -: 2.2M •o• T 0.47I: DB 1N4148 ':t" I (;I;) 100ki • _- 0.47I~ ~I THRESHOLD 4 VR4 200k +5V .. STANDBY INPUT + I "--.. 141 sv '♦♦• 2.ZM T 0.47I- 9 ~ 4 o 220k Wlf IN Os6. 'O➔---.---, THRESHOLD 3 VR3 200k ' i6 T 0.47 1 I r..,.----.1-I~- ' 100k -$ l 04 1N4148 ~\•No~ +5V r STANDBY T 1 INPUT 2 0 ,rn .,. t THRESHOLD 2 +5V STANDBY I ? 0-..---.....---, +.___,.__ _ _, T INPUT O OUT THRESHDI.D VR1 200k1 - - - - - - - - . . . . 1Nf1\a( 220ki 100k < T - LOW TO HHlH\ SS I a Ck '" ST~ANOBY -+sv 7 IC211 STANDBY -+sv -.. - f{AJ~BY .,. b _L 220 k HlbH IU LUW6 = lOOk T I 403 12 ~ 1 4 11 13 LOWTOHIGH~1 HHlH TO LOW 100kt sT1~~BY I I 11 ~ IN 00 OUT ~ = -:- = T D18~ 470 16V J 16VWI 1W 100 A· ~I< D13 - '"' - l 4x1N414ar r DIGITAL VOICE BOARD • _ GND1 BATTERY +12V .,. + l ZV POWER UP INPUT OR IGNITION GND1 BELOW ~- B • E 0C ~ 7 ?~ ~10 r ~ ll III~ 111 I II STANDBY +5V T 01 r·· iw• t D14 ~ D16 Rl -I. .,. ...L.. 4.5V: + -T I SEE TEXT ' ' sTAJ~ev .,. +5V STANDBY Fig.1: the circuit is based on the TMS3477 voice recorder chip from Texas Instruments. •·l~ I • 021 Pri~~R 03 4xBC558 10k Changing sense STOP PAUSE 1 3 4 PLAY RECORD i ~t. The four 256K RAMs store the digital data generated by the TMS3477 voice recorder chip during recording. If you don't need four channels, you can save money by leaving out the memory ICs for those channels you don't want. We used sockets for the memory chips but these are optional. each of these has a trimpot to set the voltage threshold at which it is triggered. There is also an 8-way DIP switch to set the polarity for the signal being sensed. This facility allows the comparator inputs to operate with signals which are either normally on or normally off or alternatively, normally high or normally low. There are six pushbutton switches on the board and these are used for control of the recording and playback functions, as follows: Reset which clears the memory of a recording, Record, Play, Pause, Stop and Memory Select. The Memory Select switch is only used when recording. It selects the memory into which each voice message is stored. Five LEDs are used to indicate the particular memory being accessed and whether record or playback is taking place. The board also includes several trimpots. These are used for adjusting the internal oscillator (to change the sampling rate), and for setting the microphone level and the playback volume. Circuit details Now let's have a look at the com28 SILICON CHIP plete circuit for the voice board (Fig.1). This may appear complicated at first but most of it is repetitive to provide for the four separate voice messages. Hence, there are four comparators, four memory select gates and four separate memories. First, let's have a look at the four sensor input stages, each of which is identical so we only have to discuss one stage. ICla is part of an LM339 quad comparator. VRl, a 200k0 trimpot, is connected to the non-inverting input of IC la to provide an adjustable threshold. A 2.2MO resistor between pins 1 and 7 provides a degree of hysteresis and the lOOkO resistor at the output (pin 1) provides an external load which is necessary since the LM339 is an "open collector" device. The sensor signal is fed to the inverting input of ICla via a voltage divider consisting of a 220k0 and a 100k0 resistor, with overload protection provided by diodes Dl and D2. The divider allows the circuit to function with logic signals of + 12V or more, even though the board logic runs from a + 5V supply. The 0.47µF capacitor removes any glitches which may be present due to switch contact bounce. Switch S1, together with exclusive OR (XOR) gate IC2d, is used to change the sense of the comparator output. For example, if S1 is open, IC2d's output will change from low to high when the sensor input to ICla goes high. If S1 is closed, IC2d's output will change from low to high when the sensor input to ICla goes low. Thus when Sl is closed, IC2d inverts the output of ICla. IC2d's output must change from low to high for the voice message to be played back. ICla and IC2d can be disabled by DIP switch S2 which simply removes the sensor input. Comparators IClb, IClc and ICld, and XOR gates IC2c, IC2a and IC2b, function in the same way as ICla and IC2d. They also have DIP switches to disable them: S4, S6 and SB. The outputs from the four XOR gates are connected to separate inputs of each of the gates in IC3, a 4011 quad 2-input NAND gate package. The second input of each NAND gate is connected to the '1 ', '3', '5' and '7' outputs ofIC5, a 4017 decade counter (pins 2, 7, 1 and 6, respectively). As IC5 counts, the four NAND gates are sequentially enabled so that they can pass signals through from the XOR gates. Only the odd outputs from IC5 are used so that there is a time gap between each of the NAND gates. As each output of IC5 goes high in sequence, the NAND gates will deliver a low output signal only if the respective XOR gate output is high. Diode OR gate The four NAND gate outputs are connected to an OR gate consisting of diodes D13 to D16, together with a 100k0 pullup resistor. If one of the NAND gate outputs goes low, the OR gate and its associated lµF capacitor delivers a momentary low signal to Schmitt inverters IC6a and IC6b which then pull pin 7 of IC7 low, via diode D12 . IC7 is the TMS3477 voice chip and when its pin 7 is pulled momentarily low, it goes into playback mode. The NAND gate outputs perform CERAMIC & POLYESTER CAPACITORS No. D 9 D 1 D 1 D 1 D 1 D 1 Value 0.1µF .047µF .0047µF .0022µF 100pF 47pF IEC 100n 47n 4n7 2n2 100p 47p EIA 104K 473K 472K 222K 10 1K 47K two other functions. Each output drives an associated transistor (Ql, Q2, Q3 or Q4) via a 10k0 resistor. These transistors drive the memory LEDs. Thus, the LEDs indicate which comparator is tripped to play its respective voice message. Finally, the NAND outputs select the requisite memory via the four OR gates of IC4, a 74HC32. The chip select output of IC7 (pin 12, CAS1) connects to one input of each of the IC4 OR gates. Each OR gate will pass this chip select signal when it is enabled via its r espective NAND gate output. Note that we have specified a high speed CMOS OR gate for IC4 because it has to pass through the fast rise times of the memory refresh signals without degradation. Memory select At this point we should explain some of the labelling on the dynamic memory chips, which otherwise will seem very obscure. The la belling on the pins is as follows: address inputs AO-A8 column address strobe CAS data in DI data out DO row address strobe RAS write enable WE You will see that there are corresponding pins on the TMS3477 chip (IC7) for the connecting lines to the memory chips. The CAS and RAS lines are used for refreshing the data in the memories but as far as we are concerned, the CAS input on each memory can be regarded as the chip select line. When IC7 is in the record or playback mode, its CAS line is ac- Fig.2: here's how to install the parts on the PCB. Be sure to install switches S11-S14 with their flat sides as shown. The DIP switch (S1-S8) is installed with the open side nearest the edge of the PCB. tive (ie, strobing at the nominal sampling rate of 32kHz or 64kHz). The CAS line from IC7 is fed via four OR gates (IC4) to the CAS inputs of the four memories. The CAS line also goes to Schmitt trigger IC6d. When the chip select output from IC7 is active, Schmitt trigger IC6d performs two functions. First, it lets us know that record or playback is in progress by lighting up LED 5. This is done by charging up the 0.1µ.F capacitor at the pin 9 input of IC6e via diode Dl 1. The resulting low output of IC6e drives LED 5. The output of IC6d also stops the clock of IC6f via diode DlO. This holds the lµF capacitor at pin 13 of IC6f high, which disables IC6f and IC5 for the duration of the record or playback period. The Memory Catch switch (S9) stops the clock in a similar manner by pulling the input (pin 13) of IC6f high. S9 is used to select the reDECEMBER 1989 29 Switches 2, 4, 6 & 8 of the DIP switch select the inputs to be used for triggering while switches 1, 3, 5 & 7 select the polarity of the input. For low to high triggering, these odd numbered switches should be off (open). For high to low triggering, the switches should be on. quired memory for recording. The final control over IC5 is the reset at pin 15. Both IC5 and IC6 run from the + 5V standby supply which is derived from either a car battery or on-board battery. When the circuit is operating only from the standby supply, diode D9 pulls the input of IC6c low. This causes IC6c's output to go high and reset IC5. The 22µF capacitor and 220k0 resistor at the input to IC6c provide a turn-on delay when the main supply is applied. Memory The memory chips from IC10 to IC13 are wired in parallel and connect to the voice annunciator chip IC7. Note that the AO-A8 address lines of IC7 do not connect to the corresponding address lines for the memory ICs. This does not matter and is done so that the printed circuit board layout is more convenient. The 10k0 resistor connected to the AP6 address line selects the 64kHz data sampling rate. If this resistor is removed, the rate drops to 32kHz, with a corresponding drop in the sound quality. The external oscillator components for IC7 are the 47pF capacitor, the 10k0 resistor and the 200k0 trimpot. These are at pins 6 and 7 of IC7. The power up reset is at pin 5 and uses a 47k0 30 SILICON CHIP resistor and lµF capacitor. Reset switch S10 provides manual resetting. The Play, Record, Pause and Stop switches connect directly to the respective inputs at pins 8 to 11. When a switch is pressed, it pulls its corresponding pin to ground via a 1000 resistor. The microphone input to IC7 (pin 2) is driven by op amp ICBb which is fed by an off-board electret microphone. The gain of IC8b is adjustable over a modest range by VR5, a 10k0 trimpot. IC8b has a high frequency cutoff of 2.6kHz due to the 100pF capacitor across the 680k0 feedback resistor. The reconstituted audio signal from IC7 (ie, playback) is fed to IC8a, a low pass filter with a high frequency rolloff above 2kHz. This attenuates any high frequency hash which is a normal byproduct of any digital to analog converter. Following IC8a, the signal is fed to volume control VR6 and then to IC9, an LM386 power amplifier. DC bias for IC8a and ICBb is derived from a voltage divider consisting of 39k0 and 47k0 resistors and an associated 10µF bypass capacitor (shown near to the electret on the circuit). Power Power for the Voice Board is provided from two separate 5V supplies. All of the RAMs and IC1, IC2, IC3, IC4, IC5 and IC6 are powered from the standby + 5V supply while the analog circuitry, IC7, IC8 and IC9 are powered from the main + 5V supply. Both supplies are based on 7805 3-terminal regulators. The main + 5V supply is the simplest. Its 7805 regulator (REG1) is fed from an external + 12V supply via a 100 resistor and protected against reverse polarity and excessive input voltages by 16V zener diode D18. A 470µF capacitor filters any hash from the input line to the 7805. The standby supply is more complicated but uses the same components for input protection and filtering. However, the standby regulator (REG2) has diode D20 in series with the GND leg to jack up the output voltage by 0.6V which is then "dropped" by diode D21. This gives an output of + 5V which is bypassed with a 100µF capacitor. Diodes D21 and D22 are included so that a 4.5V backup battery can be included. The diodes provide isolation of the normal 5V regulator output from the 4.5V battery. If the standby regulator is powered down due to disconnection of the offboard supply, the onboard battery maintains the data stored in memory. It feeds the + 5V standby rail via D22 and provides about + 3.9V which is adequate to keep the memories powered up. Construction The voice board is coded SC07111891 and measµres 220 x 138mm. While we have not done so, it could be housed in a large standard plastic instrument case, as available from Dick Smith Electronics, Jaycar and Altronics. Construction of the board is quite straightforward. First, insert all the links and resistors as shown on the overlay diagram (Fig.2). Next, the ICs can be inserted and soldered into place. Be careful with their orientation and ensure that when soldering there are no shorted pins. The next step is to solder in all the diodes. Most of the diodes are 1N914 types except those in the power supply section which are zeners and 1N4002 types. The capacitors can also be installed at this stage but take care with the ror~====---rro:~~~ir=~, -~. 00 00 "'n ~ ~ • ~ \.....l::::::=!1111!50'45; l.!jiOOC>OOOOC~i»---11 ===-.1 ea.: ~ 0 r-0 Fig.3: here is a half-size reproduction of the PCB. The full-size board measures 220 x 138mm. T'" N M ~ ~ ~ ~ ~ ::) C ::) C ::) C ::) C c. z C, z c. z c. C, z zC, z C, ~ ~ MEMORY PB/ REC 4 3 1 2 c. C, osc RESET 4 PAUSE STOP 3 C z zC, C 2 > a: ~ := v, II + CL 12V MIC SPKR CATCH RECORD PLAY 1 1 2 MEMORY 3 4 ---.----L·H _ __.___.l_H-L THRESHOLD + + + + Fig.4: use this artwork to label the various switches and controls on the PCB. The labels can be attached using double-sided tape. polarity of the electrolytics. Now install the transistors and other semiconductors, taking care to ensure that each device is correctly oriented. Finally, complete construction by soldering in the pushbutton switches, DIP switch and other hardware. The flat side of each pushbutton switch must be oriented as shown in Fig.2. Install the DIP switch so that the open side is at the edge of the PCB. Powering up To test the circuit, a 12V supply capable of providing up to 500mA is required. Connect the power supply and check that + 5V is present at pin 3 of ICl; pin 14 of IC2, IC3, IC4 and IC6; pin 16 of IC5; pin 8 of ICB, IClO, ICll, IC12 and IC13; pins 1 and 28 of IC7; and pin 6 of IC9. If all are correct, the circuit can be tested for recording. Connect up an electret microphone and loudspeaker to the terminal strip. Now close Sl, S3, S5 and S7 of the DIP switch. All four memory LEDs should now slowly flash in sequence. To record, press the Memory Catch switch to stop the LED at the required memory. For example, to record in Memory 1, press the Memory Catch button when LED 1 flashes on. Hold the Memory Catch button down and press the Record button. This starts the recording process, as indicated by the playback/record LED. The Voice Board will then continue recording until either the stop or pause switches are pressed or the memory is filled, which takes 30 seconds or so, depending on the setting of VR7. When the first recording is complete, the record/playback LED will extinguish and the next memory will be accessed. It will begin playing back what is in its memory. Since this has yet to be recorded, you will just get a loud buzz. Now press the Stop switch. The next memory will now be accessed and this will also play back noise. Each time you press Stop again, the Voice Board will move on to the next memory. When the first memory is accessed again, it will play the message just recorded. You can re-record at a faster or slower clock speed by adjusting VR7. Recording at a faster clock speed will give better sound quality but will reduce the maximum possible length of the recorded message. Normally this will not be a problem because most recordings you are likely to make will usually be much less than the nominal 30 seconds. You should also adjust microphone level control VR5 for best results. The three remaining memories can be tested by recording as before. Note that while the Stop pushbutton can be used to cut short a recording, this will mean that the recorded messages for the remaining memories will all be cut to the same length. The Pause pushbutton operates in a similar manner to a tape recorder. It halts the recording process until pressed again. The 4.5V battery pack can now be connected to test that it maintains the memory when all other continued on page 109 DECEMBER 1989 31 Mix and Match, and grab Special Offer!! 1411 EGA MONITOR +EGA CARD CAT.ACMEGA CAT.VCEGA VGA MONITOR + VGA CARD CAT.ACVGA Full analog VGA monitor, cornpatible with all VGA graphics cards. It is able to display up to 640 x 480 pixels in up to 256,000 colours. It features a 0.31mm dot pitch tube with anti-reflective coating plus a tilt and swivel stand. MINI TOWER CASE WITH 200W POWER SUPPLY BABY AT CASE + POWER SUPPLY CATCAATBBP CAT.CAT.BP Only$875 Normally $1,148 SAVE$273 MULTISYNC MONITOR + EGA CARD CAT.ACMM CAT.VCEGA The ACMEGA is a full EGA colour monitor, providing both text and graphics display with all EGA and EGA compatible graphics cards. It features a 0.31mm dot pitch tube with anti-reflective coating. A tilt and swivel stand is provided. 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OK RAM • High speed with 0 wait state • 6MB memory on board • LIM 4.0 compatible I =lEl :::.:~:~=2111 ONLY$295 ·-----------------------------· ~ ft I == ElectrnnicSolutions I • - -- • • Fax (02) 906 5222 I == I • We accept Bankcard, Mastercard & VISA. mail orders our specialty. Freight on smaller items is now $9.00 + $2.50 P&P • All prices include sales tax • All products carry a 14 day money back guarantee (software excepted ) • All products carry a full 3 month warranty • All cards come with full documentation • Ring for quantity discounts and tax free prices Due to technical advances products we supply may in some cases vary from those pictured. In all cases they are guaranteed to perform to an equal or higher standard. I I ·-----------------------------· Knowing when to draw a line Maybe I'm cynical or superstitious but it seems that whenever I mentally register a fault as "routine" it turns out to be anything but. Instead, Murphy is usually waiting to pounce - to teach me a lesson for daring to tempt fate. Thus it was with this month's story. The customer rang to say that his TV set was playing up. The picture had vanished and all he had was a bright line across the middle of the screen - in other words, frame collapse. Now frame collapse is not usually a difficult problem; in fact, it's typically routine. I suggested that he bring the set in and that repairs should be quite straightforward. When he arrived, it was with a Sanyo model CTP8631, a 53cm model between 10 and 12 years old. I turned it on briefly while he was there, just to confirm his description. Sure enough, it was a classic example of frame collapse. I was rather busy at the time and because the customer had a second set, I put it aside for a couple of days. When I finally set it up on the bench and fished out the manual, I fully expected to find that the ver- § ··· ···. < ,.._ THE: CUS1"'0M~'R AANG .,-o s~ THA, Hl'S 1V WF\S ?l..A'-flNG UP. 34 SILICON CHIP se:.T tical output transistors, Q903 and Q904, had packed it in (a fairly common fault). They usually take out a few other components as well, particularly diodes D461 and D462. But no. A careful check of these and other relevant components in this part of the circuit drew a complete blank; as far as I could see it should be working. It was time to stoke up the CRO and start chasing waveforms. At least, that was what I would have done normally. Now I realised that the set was exhibiting a couple of symptoms that I had overlooked earlier. Other sets were operating on the bench and I noticed that, when I turned this set on, it created random white dots all over the screens of the other sets. Sizzle, sizzle At the same time I became aware of a faint sizzling noise, exactly like an EHT leakage, though not quite as loud as these usually sound. Nevertheless, I assumed that it was an EHT fault and that this was responsible for the interference to the other sets. Such faults can be quite destructive, so it was important that I fix it before worrying about the vertical fault. But it wasn't that easy. One can usually pinpoint such faults visually if the ambient lighting is not too bright, but not in this case. I turned off all the lights and it didn't help, so I drew the blinds on the windows and tried again, paying particular attention to the ultor cap, the tripler and the horizontal output transformer. Still no luck. More or less on impulse I reached for the EHT voltage probe and measured the EHT. And that set me back somewhat. In these sets the EHT normally runs at around 24kV to 25kV but in this set is was varying between 30kV and 32kV. I snapped the power off quick smart. Excessive EHT can cause a lot of damage, even puncturing a picture tube in extreme cases. I needed time to think. The most likely cause of excessive EHT would be a higher than normal (120V) main HT rail due, in turn, to some kind of fault in the regulator circuit of the main power supply. But I didn't fancy the idea of trying to track down such a fault while the EHT system was doing its imitation of a sausage sizzle. On the other hand I needed to apply power. The simplest approach seemed to be to fire the set up via a Variac, bringing the voltage up gently to assess behaviour, while keeping the system below the sizzle level. So that was what I did, connecting a voltmeter across the main HT rail to keep tabs on it. I brought the rail up to about 100V, at which point all was quiet, but I had been paying more attention to the meter and the vital EHT points than the screen, which was facing away from me. When I did check it, I received another setback - in a cockeyed kind of way - for there in place of the thin bright line was a full size picture. From a serviceman's point of view I don't know which is more puzzling; finding a line when there should be a picture, or finding a picture when there should be a line! I checked the EHT at this point and it was close to normal so I edged the Variac up gently, trying to keep an eye on everything at once. And suddenly, as the HT rail was approaching the 120V mark and the TRIPLER EHT --------------7 rI I TO BEAM I L~ R607 1k R617 220k R612 470k R611 330k R613 R614 R616 220k 270k 270k I v~~ I I I I I 700k I I L I I R605 270k o2 CRT UNIT 85PH ------------------ I j Fig.1: this diagram shows the divider network which supplies the G2 voltage in the Sanyo CTP 8631. Note C603 (1µF) which is common cause of trouble. EHT was getting dangerously high, we were back into sizzle country again and the picture collapsed to a thin bright line. I switched off smartly. Weird symptoms Well, here was a weird set of symptoms if ever there was one. But there were a couple of others I had noticed while the picture was on the screen. It was overly bright for what I took to be a normal brightness setting and more importantly, was exhibiting vertical retrace lines. These were vital clues but I didn't appreciate this immediately. I was still trying to figure out the source of the sizzling and why it was causing the vertical system' to collapse. I also wanted to know at what point the vertical deflection was failing. The vertical and horizontal drives, along with a number of auxiliary functions, are generated in a 24-pin chip, IC401, type LA1463. The vertical drive comes out on pin 5 and runs straight to the base of vertical output transistor Q904. I attached the CRO probe to this pin and with the set running on reduced input voltage, confirmed that the waveform here was essentially as shown on the circuit. Next, I wound up the Variac until the vertical deflection collapsed, held it there just long enough to check the CRO, then backed off. The answer was that the waveform out of the chip vanished when the fault appeared. This at least cleared the vertical output stage but did little to suggest why the excessive EHT was shutting down the vertical oscillator. On the other hand the real fault was the one causing this excessive voltage. Find that and I shouldn't have to worry about what was really a side effect. But what could possibly cause the EHT to go high? While horizontal output transformers develop faults from time to time, I've never known one to behave like this. Reduced voltage, yes; excessive voltage, never. Much the same applies to triplers. But it so happened that I had a spare tripler on hand and it took only a couple of minutes to patch it in. After all, funnier things have happened. But it was a waste of time; the results were exactly as before. G2 voltage It was then that I realised that the symptoms, when I forced the vertical system to work, were more significant than I had previously appreciated. A common source of trouble in these sets - and some other brands as well - is a voltage divider network from which the picture tube's G2 voltage is derived. In this set the voltage divider is connected between the lower end of the EHT winding and chassis (the chassis connection also involves the beam limiter network). There are seven resistors in the main divider network: R607, R617, R612, R611, R613, R614 and R616, in that order (see Fig.1). In addition, there is a 700k!l pot (VR601) connected across R612 and R611, the moving arm of which supplies the G2 voltage via R605 (270k!l). Another vital component here is C603 which is a 1µ,F electrolytic capacitor. Partial or total failure of this capacitor will either darken or black out the screen. I'm not sure of its exact function but I imagine that it's there to filter out any remaining ripple which might otherwise upset the beam limiter circuit and bring it into action prematurely. It is a fairly common fault. Screen brightness can also be reduced by total or partial failure of resistors at the high voltage end of the divider (eg, R616). This lowers the G2 voltage and is a fault I have encountered several times in the past. But I was looking for increased brightness plus excessive EHT. Could some other failure here account for this? I pulled the neck board off and one glance was enough; all the main divider resistors were showing signs of distress and one of them, R617 at the chassis end of the network, measured open circuit (note I said "measured"). I promptly replaced the whole chain, plus C603 for good measure. Then I switched on and up came a near perfect picture, being just a little on the dark side due to the Variac being turned down. Restoring full mains voltage cured this and there were no further complications - ie, normal vertical scan, no sizzling and no interference to other sets. That was it. Unfortunately, I can't answer all the questions which this fault raises. The hardest one is why the fault shut down the vertical oscillator. Quite frankly, I haven't a clue. Next, where was the sizzle? I never did find it but my tip is that it was on the neck board, on the component side, facing the front of the cabinet. This cabinet is fairly deep and there is no way that one can view the front of the board while it is in situ. And why did the open circuit resistor cause excessive EHT? How, in fact, did the circuit work at all? I suspect that the resistor DECEMBER1989 35 SERVICEMAN'S LOG -CTD which measured open circuit on the ohmmeter behaved quite differently in the circuit. More specifically, it was probably behaving more like a very high value resistor, breaking down across the fault and generating the sizzle. And in this condition it jacked up the EHT, either directly due to the increased resistance, or indirectly because it reduced the current drain. In any case, any voltage increase in this part of the circuit would be multiplied by the tripler. Which is about the limit of my speculation. If anyone has any other ideas I'm sure readers would be interested. But, as I hinted earlier, never take a "routine" fault for granted. To change the subject, here's a story from my colleague J.L., in Northern Antarctica, across Bass Strait. As so often happens, something which started out looking like a lost cause finally had a happy ending. Here's how he tells it. J.L.'s story Sometimes customers give the most misleading description of the symptoms their sets are displaying. One such came in recently with the rep9rt, "No colour". The set was an early model HMV, a 12613, otherwise known as a "Braddon". At first I took the customer at his word. As is typical in such situations, when I set it up on the bench it produced a perfect colour picture. This introduction to the problem set the stage for my battle over the following two months. The set normally lived in a country town, some 100km away amid high hills. It was possible that the colour loss was due to a weak signal, so I set about reducing the signal with a series of coax attenuators. All of which proved nothing because the colour remained steady until the picture was about to disappear in the snow. I could do nothing more than return the set to its owner with instructions about a good antenna connection and proper fine tuning. I heard nothing more for a week. When the set came back it was with the explanation that the colour had been good for several days, then it disappeared and returned at irregular intervals until the owner decided to bring it with him on his next visit to town. On the bench it upset its owner by firing up with perfect colour. But only for five minutes. Even before he left the colour had gone, only to return intermittently for the rest of the day. But more importantly, I had seen the fault for the first time and realised that the customer's decription was only partly correct. There was some colour with faces being shown on screen as red. Just the faces - the rest of the picture was indeed monochrome! When there were no faces on screen, any red or orange item was coloured but everything else was monochrome. It was rather like a newspaper illustration in which highlights have been picked out in garish colour. In between times the colour returned and produced quite a good picture. At these times I tried all the usual tests, like thump and bump or heat and freeze, in an attempt to disrupt the colour. The only thing I learned from this was that adjusting the fine tuning could produce the strange "red faces" effect. Unlocked chroma 7) '7NE SUCH C..AMe: IN W\1'\,\ "TI-\~ 'R~'PoR-r '' NO COI-OU'R '' 36 SILICON CHIP But there was another strange effect; tuning from sound bars into the picture produced nothing unusual but tuning the other way, from a monochrome picture towards colour, produced a picture with unlocked chroma. I couldn't imagine why the chroma should be locked when fine tuning one way, and unlocked when tuning the other way. But it was a possible clue and I spent much time swapping crystals and integrated circuits in an attempt to secure stable locking. The intermittent nature of the fault gave me many false alarms but in the end it was always back to either red faces or unlocked colours. The only hint of a clue was that the go/no-go state might have been slightly sensitive to the angle at which the chroma board was sitting on its socket. This made me hope that there might have been a dry joint under the socket, so I upended the chassis and resoldered all the pins under the chroma board socket and a few others that looked a bit doubtful. Then I re-tensioned the contacts on the board itself, just for good measure. After all this I thought I might have really cracked it because the picture came up perfect, with no sign of unlocked chroma no matter which way I fine tuned the set. After all my hassles, this had to be a cure so the set went back home next time the owner came to town. I should have known better because it was back again within a week. It was the same problem and thoroughly intermittent to boot! The symptoms did not point to any clearly defined fault. The unlocked colours might have indicated a reference oscillator fault (and note that this set has two oscillators, running on different frequencies!) while the fine tuning requirement might have indicated a bandpass amplifier fault. Several other less likely troubles also suggested themselves. As an aside, the use of two reference oscillators is a rather novel arrangement in place of the usual flipflop, line alternation, PAL switching system. One oscillator runs at the conventional frequency of 4,433,618.75Hz and the other is offset by half the line frequency and runs at 4,441 ,431.25Hz. There are two decoder circuits, one for the B-Y signal and one for the R-Y signal. It became clear that I was going to need a set of extension leads so that I could test and adjust the chroma board out of the chassis. I had no idea where I might get such a set, so I cast around for bits and pieces to make into a suitable lead. Funny sockets You mightn't believe this but I tried dozens of plugs and sockets from dozens of different sets and all of them were either too big or too small. It seems that this particular HMV was fitted with odd sized sockets that don't match any other set sold in this country. It seemed that I was going to have to hardwire each plug pin to each socket terminal. ~-~ ~ 0 I ' I I' ~ -t' / , ~ , / I :t -rR ,~o AL-L- -o-t«;: \JSU~l-"'11::S-rS,L\K ~' SUMP P\ND 11-\UM'P ~ OR l-\~-r AND 'f'RE:E'Z.~ •.., There was only one adjustment on the chroma board that I was prepared to fiddle with while the board was in situ. This was the killer threshold trimpot and a small movement of this control brought back full colour, without any of the earlier tuning problems. What's more, the set ran for a fortnight in my workshop without a glitch. The only problem, if it could be so described, was that we now had confetti on the blank channels. Putting the killer back where it had been stopped the confetti but restored all the problems! So the set went home with the killer set fully high and my hopes for a long and trouble free life. I wasn't really happy about the job because I hadn't found and fixed the fault - I had only masked it. The customer had no grouch so long as the set worked normally onchannel. He had no interest in what it was like off-channel but it still worried me. As a result I was not too surprised when the set came back a couple of weeks later. It was back to its old capers and this time I had to fix it once and for all. Eureka - as they say At about this time I had an inspiration. I remembered that my son had an identical model. So I gave him a loan set and borrowed his HMV to give me a known good board for comparisons. My first test was to put the good chroma board in the doubtful set. This confirmed that the fault was on the chroma board because the client's set was now perfect. More importantly, when the client's chroma board was fitted to my son's set, it became as troublesome as the client's set. I had already replaced the three chips on the faulty board so I assumed that these were OK. Next I checked the rest of the semiconductors and compared them with their equivalents on the good board. Only one transistor showed any difference and I replaced this but without any improvement. Next, I checked all the fixed inductors on the board by testing DECEMBER1989 37 SERVICEMAN'S LOG -CTD I I ~w•,rri~--1~4~-~2 cso2 i I them for DC continuity. They were all OK so I began testing other coils and transformers, about eight in all. None of the transformers gave any indication of being faulty during my initial continuity check. It was only when compared with the equivalent unit on the good board that any sign of a difference in one of the coils showed up. It was the first coil on the board (although by Murphy's Law it was still the last one to be checked), L501. This is the chroma input coil and consists of a tunable shunt coil and a series capacitor. It is fed with raw chroma from pin 1 via a 120pF input capacitor and in turn feeds clean chroma to pin 2 of IC501. My first test was for continuity from pins 1 to 3 and this checked out at less than rn on both boards. The second test was from pin 4 to chassis, thus checking the integrity of the capacitor. Here the good board showed 2.2kn while the bad one showed much less, varying between 4200 and 8200, depending on which digital meter I used. I removed the whole coil/capacitor assembly and rechecked the resistance from the (now empty) pin 4 connection on the chroma board to chassis. It was 2.2k0, just as in the good board. As a quick test, I shunted connection points 1 and 4 on the board with a lOOpF capacitor. At switch-on the picture came up trumps - good though noisy colour and perfectly stable. Now that I knew what the trouble was, I was faced with the problem of curing it. This chroma input coil would have been an unlikely spare part, even when the set was new. Now, 12 years on, I wouldn't give tuppence for my chances of getting a replacement coil from any of the usual sources. It seemed that the best thing to do would be to find a similar coil in another set. The most likely source would be a Rank Arena because TV TEST EQUIPMENT (AUSTRALIAN MADE) I csoi L501 I 1 J I I I I__ 47pF 5 ~~ I I 3___ .J Fig.2: this is the circuit for the chroma input coil in the HMV 12613. While simple electrically, it is difficult to work on mechanically. they use the same chroma amplifier chip. However, examination of several Rank boards showed there was no similarity between the equivalent coils. So that line of investigation came to a dead end. So, if replacement was not going to be easy, would repair be any easier? Closer examination of the L501 package strengthened my conviction that the capacitor was the culprit. It seemed to be leaky, although there remained a slight possibility that the leakage was in the coil base material itself. There AUDIO TRANSFORMED SHORTED TURNS TESTER Built in meter to check EHT transformers including split diode type, yokes and drive transformers. $78. 00 + $3.00 p&p HI-VOLTAGE PROBE Built in meter reads positive or negative 0-50kV. For checking TVs, microwave ovens. $84.00 + $5.00 p&p. 1 TELE·TEST TUBE TESTER & REJUVENA TOR Removes cathode grid shorts & rejuvenates picture tube. Suitable for all colour tubes. 12 months warranty. $420.00 + p&p. NEW PRODUCT DEGAUSSING WAND: A must for all workshops. Efficient design, strong magnetic field, low heat, double insulated with momentary on/off. $75.00 + $1 0 p&p. ALSO TUNER REPAIRS FROM $17.00. Cheque, Money Order, Bankcard or MasterCard Y.V.TuNERs) 38 SILICON CHIP 216 Canterbury Road, Revesby, NSW 2212. Phone (02) 77 4 1154 FOR PROFESSIONAL, OEM OR AMATEUR Broadcast qual ity audio transformers ex-stock Mo re than 70 standa rd types availab le Fast protot yping se rvice for non-standard types Co mprehensive data available on requ est Locall y manufacture d Competitively priced HARBUCH ELECTRONICS PTY LTD 90 George St .. HORNSBY NSW 2077 Ph one (021476-5854 was only one way to find out. The trouble was, any kind of work on the package didn't look to be particularly easy. It is very small, the can being about 10mm square and 12mm high, and removing the assembly from inside the can without damage is difficult to say the least. So the alternative was to work inside the can to isolate the capacitor. Using a powerful magnifier and working with the fine tip of a sharp craft knife, I cut one of the capacitor leads. This removed all trace of the leakage between pins 1 and 4 and proved conclusively that the capacitor was the culprit. i carefully cut the other lead and tried to remove the capacitor from the coil body. It came out in two pieces so I don't know if that was the problem or the result of my ministrations. Whatever it might have been, there was no further sign of leakage across the base pins. I re-fitted the coil, and replaced the missing capacitor with an external 47pF ceramic tacked onto the back of the board. The problem licked At next switch-on I had the problem licked. Perfect colour, no chroma hash, and no sign of instability due to the fine tuning. I still had the confetti off-channel but that was easily curable with the killer threshold pot. I'm sure that the set will never come back with that particular fault. But in retrospect, I can't help wondering how I would have found it if I had not had the good board from my son's set for comparison. The extension leads might have helped by makin_g scope .inspection possible. But I wonder . It was the ohmic disparity that really solved the problem. As a matter of interest, I tried to duplicate the fault on the good board by dabbing a 5600 resistor across the capacitor in 1501. It killed the colour all right. But totally! Nothing I could do would give a repeat of the red faces or unlocked chroma. Comment Well that's J.L.'s story and it prompts a couple of comments. It so I 0\ s c; <at>J~g,. ...... S-,;;- s~v~AAL 011-\ER l-~'SS L..\K~l-'1 -r'ROU'Bl-E'S A.L.'SO s \JGGes-r-E,0 ~e:M~eL-ve:s.o. happens that I have one of these chassis in the workshop right now, exhibiting a particularly stubborn fault. Tracking it down may well make a story in its own right but that's for the future. The point is that this one is a General chassis, model GC18A, which is the true origin of the HMV 12613, which was also marketed under the Healing label. More importantly, good stocks of spares are still available from the General Corporation Japan (Aust.) Pty Ltd, 10 South St, Rydalmere, NSW 2116. I recently obtained an IF transformer from them and they also supplied my extension leads for the chroma board. They came as a kit of four leads (three 6-pin and one 3-pin). This was some time ago now but they may still have some. So, next time you tackle one of these J.L., this information may make things a little easier. ~ TETIA TV TIPS AWA C6319 (Q chassis) Symptom: Overbright screen, with no control of brightness. Retrace lines are obvious and persist at all settings of the CRT bias control. Replacing the usual electrolytic capacitors has no effect. Cure: R251 (1. 5MQ ½W) open circuit between VR25 1 CRT bias trimpot and the Vee supply to the video output transistors. This fault is confusing because the bias trimpot seems to adjust the screen voltage as might be expected. Al pine Cassette Deck, Model AL51. Symptom: Mechanism completely inoperative although panel lights show that power is reaching the unit. Cure: Either or both of two faults: ( 1 ) the counter belt is broken or misplaced or (2) the reed switch on the counter is stuck. A magnet on the counter shaft rotates in normal operation and causes the reed switch to produce a series of pulses which unlatch the auto stop circuit. Without these pulses the machine thinks it has come to the end of the tape. TETIA TV Tip is supplied by the Tasmanian branch of The Electronic Technicians ' Institute of Australia. Contact Jim Lawler, 16 Adina St, Geilston Bay, Tasmania 7015. DECEMB ER 1989 3-9 Test ,nst•u111entsl NOTHING BIJT THE BEST? High Performance - Low Cost! Digital Multim r The DSE 0-1440 Digital Multimeter proves that great performance doesn't have to cost the earth. With features and specifications worthy of many digitals costing much more. Latest IC technology is used to achieve the lowest possible component count - ensuring reliability, accuracy, and stability. It's durable and easy to handle. Includes fully shroudeJ probes for maximum safety. Requires only one 9V battery. • DCV: 2.20. 200. 1000 V • ACV: 200, 500 V ,----TI - ,- TT - m - ,.,. - nr.--. • Cwmnt: 2. 20. 200tllA (AC or DC) • Res: 2k. 20k. 200k. 2Mol11111 • Diode & T1111Sistor clMcl( Cat 0-1440 Bargain! Temperature To Voltage Converter It's ideal for service people. industrial electricians. schools. labs .....anyone who works with heat. heat exchange. etc! Used in conjunction with a voltmeter (multimeter) accurate tem~rature readings can be taken from -50°C to 1300°C or -58 Fto 2372°F. Unit is powered by a 9V battery. fits easily in one hand and comes with bead type thermocouple on 411 lead and banana plug connectors. Specification: Ideal For Sparks! RangesDCV: 40DIIIV. 4. 40. 400 (9M 0~111 l111p) ACV: 400. 700 Clrmnt (AC/DC): 4rnA. 40111A, 400111A. 2A, 20A Resistance: 4K. 40K. 400K. 4M (~111} rr;;;~;;;;;;;;il Freq11t11cy Cerlnter: 4KHz. 2DKHz I> °") nnn Max volt. lor freq.: 250V AC LI LI.L! Conlinwily: lllzztr (t~m~old approx 1.7K 0~111) Vertical bandwillt~: DC to 6.5MHz (-3dB) Attmator: 1/1. 1/10. 1/100 and groond Horizontal sensitivity: 250rnV/div or 111011 Ti1111b1se: lOHz to lOOkHz Sync: Extemal or internal 111111111111: II. I C/F II 200 V11111 1°C/F 112v,... Mlll-¥11111111~ !1,1!: 60VDC er 24VAC O Input hnuedance: 1 Meg/35pf Cat 0-1430 Cat 0-1200 Just s5995 1 Digital & Bargraphl 1g1t Auto Ranging D M All the features an electrician needs. With a huge 21 mm LCD display, pushbutton switches for mode and function selection. full range of measurements including AC/DC volts & Amps. resistance, diode. continuity and frequency. Features audible continuity test. auto ranging on DC, over range indicator, data hold, etc. etc. Plus it's shock resistant and fully sealed against water and dust. 6 Here's a great one for the workbench at home. etc! We all know a good oscilloscope is probably the most useful piece of test gear you can own. Not only Is it good value, but it offers some surprising features as well. Including retrace blanking for a clearer display. internal or external sync and usable response to beyond 6.5MHz. Low drift and quick warm-up make it perfect for service work, around the shack, in the class room. etc. Specifications: Minim: ·50°C te l300°C -58'0 f ta 2372°f s4995 Superb Performance! ulti 399 Invaluable! ter Afantastic all rounder for hobbyists. technician and service people alike. Both digital and bargraph displays gives you the best of both worlds. Large 30 position rotary dial for function and range selection makes it quick and easy to use. Superb features include automatic overload indication. high surge voltage protection (1.5KV -3KV). capacitance measurement, diode and continuity. transistor hFE test and frequency measurement. A essential piece of test equipment tor anyone working with AC current. It senses magnetic field so it's the safest way to work• there's no connection to the cable under test. Senses any current above 60 volts (approx.) and gives visual and audible indication. It can detect the difference between active and neurtral/earth. Fits neatly in the pocket and comes with pocket clip. Powered by 2 x G13 batteries. Also fantastic for finding breaks in cables. Cat Q-1530 Ranges. Cat O-H,i4 DCV: 20IIIIV. 2V. 20V. 200V. I 000V ACY: 20IIIIV. 2V. 20V. 200V. 75811 DC CIITIII: 200IA. 211A, 200rlA. 20A AC C1ITIII: 211A. 200rlA. 20A 11111st: 200. 2K. 20K, 2M. 20M l•I IIINe Clllck: UV <at> IIIA F,... CIIII: 28Kllz. 200Qz CNit:ilNcl: zooo,F. 200rlF' 20IF Essential Equipment! It's Got The Loll .. cara:-1s2s Electronics/Electrical Formul Calculator The incredible Casio fx-61f is, without doubt, one of the most useful tools anyone working with electronics could have. Makes electrical/electronics calculations a breeze with 27 of the most used electronics formulas built-in: resonance frequency, impedance. voltage/current gain ... everything! Includes 74 scientific functions, 10 digit display, programmin9 functions and comes complete with comprehensive manual ana ·son protective case. cat V-3828 Just s7995 4.5 Digit Multi ter Superb features, high accuracy and rugged reliability make this the pick of the bunch. A beautiful piece of equipment. it's ideal for the serious minded hobbyist or technician. The easy to read 15mm high contrast LCD display and data hold function makes service, repair and test work quick and easy. With capacitance measurement. diode testing, transistor measurement. frequency measurement, data hold, 4.5 digit accuracy plus rugged construction for a trouble free life. 1 199 Ranges: DCV: 2DDrlrV. 2V. 20. 200. 1000 ACV: 20011V. 2V. 20, 200. 750 DC Clmtlt: 20011A. 211A. 200111A. 2OA AC C1mtlt: 2111A. 200rlA. 20A Reslsllftce: 200. 2K. 20K. 200K. 2M. 20M (0~11) fl'll!lllt!Cy Cerl"1er: 20KHz. 200KHz CIIIICillllCI: 2000pf. 200nf. 201F Cal 0-1528 CHA RGERS A POWER SUPPLIES Slimline Battery Charger 12V <at> 1 Amp Convertor Designed to change the two most popular batteries - AA and 9 volt. Can charge up 6 penlight (AA) Nicads and IX Volt batteries at once. Includes indicator LED fo,r_.....,_.,-,£,~ each cell. cat M-9508 Perfect around the workshop or nome. Simply plugs into the AC socket and gives 12V <at> 1 amp. Comes complete with battery nap connector and 4-way connector. Cat M-9570 s2295 Versatile Power Supply Bargain Nicad Charger The ideal power supply to have around the house. Select any one of six voltages - 3, 4.5, 6, 7.5, 9 & 12V (<at>300mA) covers most household applicances. Cat M-9526 A great way to save money on batteries and make sure you've always got power when you need it! The DSE Changing Cabinet charges all the most common batteries, up to 8 at once, in any combination - AAA, AA, C, D & 9 Volt. It is mains operated and comes with built-in test meter. Cat M-9505 s1s95 Only s39 95 3,6,9, 12V DC High Capacity Nicad Charger <at> 1 Amp Same great features as the cnargrng caomet aoove, except tnIs one is tor high capacity NiCads - 600mAh AA, 1.8 & 2Ah C and 4Ah D cells. Does not have test meter. Cat M-9506 This one is not only good for the home, but also perfect for the workbench. With DC connections via screw terminals on front of unit of easy connection and disconnection. ~~~-ioJ glarm systems, intercoms etc. Nicad Charger Only s29 95 s39ss Most chargers these days allows tor an external charger to be plugged into charge Nicads (usually a 2.5mm socket). This charger is ideal for all Nicad packs from 6 to 10 cells (i.e. 7.2 to 12 Volts). Cat M-9517 $ 3 - _ 1795 3,6,9V Nicad Batteries You won't be short on battery power when you need it with these great value NiCads. Just think about the money and waste you'll save. Type Cat No. Price AAA AA C D 9V 1SOmAh 0.5Ah 1.2Ah 1.2Ah Full Output! S-3305 S-3300 S-3301 S-3303 S-3308 $3.95 $3.95 $9.95 $9.95 $19.95 <at> 2OOmA Here's a great way to save money on batteries. Three of the most used voltages makes it ideal for a huge range of battery powered equipment. Cat M-9525 Just s17 95 SOCKET ED BREAD BOAR DS Ideal for designing/tesing your own circuits ideas, etc. High quality breadboards which can be paralleled for larger circuits. Laid our in alpha-numeric format for easy track identification. With Panel! Same size as above but with panel which allows mounting of pots, switches, T0-3 transistors, etc. cat H-4617 Jumpwire Pack The fast, easy way to maKe your breadboard connections. Handy pack with 100 pieces of colour coded , insulated wire. Ends are bent for convenient installation. Wire is 22AWG and in lengths of .2, .4, .6, 1. 2, & 4 inches. Cat H-4014 s595 SA VE $6 Just ~~~:::::::::::::::::::===-- , s1995ea ~ MAINS POWER ADAPTORS ~'.~~"'~r~~~~;~1~!~~1••!~!!!!.,~ !,~~;,~ '"'"' ~!!~~1;!'!,~~~!..~~!,e!!!,, etc from dangerous power spikes and surges! 'Power Sale' could save you a fortune in repair or replacement costs. With built-in circuit breaker, master switch with pilot light, voltage surge/spike protection (uses MOV's), clamps spikes, etc, within lightning fast 10n sec. and incorJ)orates a noise rejection filter network with a frequency range from 1KHz to 100MHz. Cat P-5618 s5995 l,w, ,v, ,"-~ i ,.j ~~ ~w-·-· - _. I ,fV, ,(·~ ,~, Super Convertor 240 volt to 110 volt (1650W) convertor for operating foreign equipment from Australian mains. Suitable for hair dryers, shavers ... anything with an electric motor. Not suitable for hi-fi, computers (solid state) equipment. Cat P-5653 Only 500 Available L ~tl~ cdi l'ia.. ... lP" --- International Mains Adapto QM .,:_ . , ·. ~i Adapts iust about any mains plug to our 3-pin plug and viceversa! Use_s ac/ive/neutra! pins only- does not connect earth. An essential piece of equipment for anyone who's travelling . (Does not adapt voltage). Cat P-5652 • s2495 t"' lli!•J 2°' ;1 I 1 (., to accept plugs form Europe, America, Japan, etc. Does not adapt voltage so rating must be compatible. With multiple earth pins for new overseas systems. $895 Cat P-5655 0 \ Play Music/ Talking With... Creative Music System The Speech Thing The Creative Music Synthesizer card simply plugs into your IBM compatible and allows you create your own stereo sounds. With 12 channels (Voices), stereo output, 32 preset instruments and a stereo amplifier to drive speakers, headphones, etc. Define your own instruments, play ,-.i··~""background music, create albums of your favourite tunes and play them in any sequence or compose your own music ... it's fantastic! How long since your computer's had a good conversation? "Speech Thing" is a complete hardware and software package which adds sound capability to your PC. Converts text (either from keyboard or ASCII files) to high quality speech. Simply plug Speech Thing into the parallel port and keyboard (comes with adaptors) - and it doesn't interfere with their operation . Can be used in conjunction with the 'Voice Master' (X-2038) to sample and edit digital sounds. Cat X-2020 s299 Cat X-2036 IBM AT Compatible 80286 Motherboard Ts/111 What to do/ Building your own computer or upgrading the old one? Our new 12MHz motherboard is the way to go for the ultimate computing power. DRAM not included. Look .... • Expandable to 1Mb using 256K chips• Expandable to 4Mb using 1Mb DRAM chips• Keyboard or hardware selectable 8112MHz operation • Six 16-Bit and Two 8-Bit expansion slots. • Selectable for RAM speed - 80 or 100 nanosecond e Selectable from Owait states on read operations (with 80 nanosecond RAM) • Socketed for 80287 Coprocessor • Performance - 13.7 using Norton S.I. • Battery backed real time clock on board • AMI Bios ROM's included • OK RAM supplied s49ss IBM/Apple Joystick Versatile, fantastic value and it can be used on either IBM or Apple II compatible computers. Lightweight and comfortable it's the best way to get into those fast action games. Cat X-3570 s199 s499 Bargain Super Mouse Casio fx-61 f Calculator Outstanding quality at a barQain price! Plugs into any serial port and comes with 9-25 pin adaptor. Complete with set-up disk, drivers, manual, Dr Halo paint program, mouse Pad and 'mouse house' so you can pack it away when not in use. Fully Microsoft compatible. Cat X-3805 s3995 ,,,;;.----~ ~ f ~~rs~o?!es your Serial port. Cal X-3806 $129 Arcads Quality/ It's one of the most useful tools anyone workin9 with electronics could have. With 27 of the most used electronics formulas built-in! Resonance frequency, impedance, voltage/current gam .. .everything! Includes 74 scientific functions, 10 digit display, pro~ramming functions .. .. it's unbelievable. Cat V-3828 Just $ 79 SS Quality Disk Drives Commodore/Atari Joystick Easy to install fn any IBM compatible! Great value half height floppy disk drives in all of the available configurations. Can be installed as an internal drive or externally (with optional case.) It's almost indestructible! Uses microswitches for the ultimate in speed and reliability. With twin fire buttons. It uses the same mechanism they use in arcade machines ... so you can be sure it's built to last ... and last.and .... ! 3.5" Disk Drives Cat X-3831 WITH 3 YEAR WARRANTY! Just With Electronics/ Electrical Formula/ With Dr Halo/ RS-232 Multilink Adaptor ~Jih12654 Voice Master How often have you wanted to tell your computer what to do? With Voice Master you can give it verbal commands. You want DOS? Just TELL the computer and it'll get it for you . Comes complete with headset and software which allows you to experiment with voice recognition . With it you can set up to 256 different voice activated keyboard macros. Installation requires an 8-bit expansion slot. The perfect match for "Speech Thing"! Cat X-2038 Cat X-1002 A complete in-line tester, adaptor which makes complex and time consuming Serial connections a breeze! Comes fitted with 25 pin male connector and 25 pin female connector. With 1·umper pads and wires, 24 in- ine switches and 8 bicolour LED's which monitor the lines and tell you at a glance when you 've got it s149 $249 1.44Mb Version. Needs DOS 3.3 or higher. S299 720K Version. Needs DOS 3.2 or higher. Cat X-2220 Cat X-2221 5.25" Floppy Disk Drives 360K Cat X-8012 S 199 ·G . El EID D 1:113 DEIDEHI aaaaa 1:1amam Bargain AM CB Bargain Marine Transceiver An exceptional value AM CB that's now even better value -you get a FREE mobile antenna! Quality construction and reliability are built in. Intended for mobile use it comes with mounting hardware and microphone. With optional power supply it can even be used as a base station. Ftatu11s: • Co111t11cl (Only 160 X44 X 122111ffl) The incredible 'Sea Simba' 12 AM marine transceiver is perfect for coastal boating. Superb quality and reliability are built in with features you'd only expect on models costing$$$ more. • All 4"0 ctlmels Extra Range With SSBI With 12 channels (10 fitted) in the 27MHz marine band, automatic noise limiter, PA and extension speaker jacks, LEO level indicators and channel readout plus RF and Mic gain controls. Comes complete with mounting hardware and microphone. Cat 0-1718 power • Blill-in noise ll111H1r • Di1it1I channel readout & pow1r/str11ngth indicators • Easy ·to Optl"III • MIXifflllll lepl Super To The sensation Super Tomcat AM SSB mobile CB comes at an incredible low price yet sports some astounding features! With maximum legal power on both AM and SSB, all 40 channels, the extra range and performance SSB offers .... and, with optional power supply, it can even double as a base station! It's easy to operate with LED power/strength meter, RF pain control, clarifier, PA facility, automatic noise limiter and more. Comes complete with mounting hardware, microphone and full instructions. Cat D-1713 Cat 0-1450 Now Just 5 Just 5 199! 89 __________..,. Marine Antenna Latest 1990 Edition! Our most popular 27MHz marine antenna! It's ground independent so it doesn't require a ground plane for proper operation which makes it ideal for wood, fibreglass and cement boats. Features an easy to use swivel deck mount and S0-239 termination for coax connection. WIA Radio Amateur Callbook The lastest and most complete listing from all around Australia. In easy to follow, state by state order. Covers call sign suffixes, shortwave and Department of Transport & Communications information. Cat 0-4069 s49es A:· Cat B-2331 sgeo ------------- A great ~uy! ~ With direction finder! Quali ul · A great one for the keen radio listener, or the boat owner who wants to know where he is! A superb radio with 6 bands including all 40 CB channels, shortwave and VHF. Plus there's a built-in direction finder to help plot your position against AM radio stations. A variable BFO also allows reception of SSB marine signals. AC/DC operation and, with on optional mic, it doubles as a PA amplifier. Comes with manual and SW listening guide. Cat D-2832 1990 MORE GREAT TOOLS! Australian Radio Amateur CALL BOOK Gas Powered! Professional ·Pocket' Soldering System Only Perfect for when you're out in the field or for those spot repair jobs. The complete portable soldering kit from Portasol. Comes in handy plastic carry case, you get butane powered soldering iron giving the equivalent of 10-60watts and temperature adjustment upto 400degrees Celsius, 4 tips including hot knife and blow torch and tip cleaning sponge. ;gT-13794 Working with PCB's can be incredibly frustrating and time consuming. The Arlec Supertool takes car of just about everything. It sands, it polishes, it drills, it engraves, ,t mills ... . you name it. Comes complete with wire brush, milling cutters, grinding wheel, high speed drills, chuck collets, eraser sticks and plug page. All in a handy carry anywhere plastic case. Just 69 5 ~~ Economy Pencil Blowtorch Great for heatsink work, silver soldering, gold, brazing, glass work, etc. Fits in the pocket and it's powered by butane gas. Amazing value it's the ideal tool for handyman and tradesman alike. Cat T-1380 s14es ~ 15 Watt Hobby Iron Mains powered, general purpose iron that ideal for project building, service and other low heat applications. Rated at 15 watts it saves cooking components in PCB work. It's well balanced to help make work easier and made by Weller so you can rely on the quality. Cat T-1310 i»XPRESS ORDER BY PHONE - 008 22 6610 (LOCAL CALL FEE) OUTSIDE SYDNEY SYDNEY AND ENQUIRIES - (02) 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 149 ~°' ~ c-<<>~ -D~ Perfect For PCB Work! Arlec Supertool CatT-4754 F,=,sol __]~ - -~ 5 Incredibly Versatile! 3-ln-1 M ool S stem • IT'S A DRILL • IT'S A SOLDERING IRON • IT'S A SCREWDRIVER • IT'S RECHARGEABLE You won't find a more useful tool for the home or workshop. The incredible 3-in-1 does it all. Modular components snap onto the rechargeable battery pack (pistol grip handle) and in seconds it converts to the tool you need. Comes with assorted drills, screwdrivers, solder accessories and charger. Cat T-5712 sgg .. ALL NEW K.I :SNOW AVAIL Simple FM Transmitter For The 2M Band Improved Light Chaser The first in a great new series of easy to build projects for the amateur radio enthusiast. It's designed to make setting up and construction easier so the novice can more readily follow the operation and therefore gain more confidence in its use. The solid state NBFM transmitter module produces over 1 Watt at 144MHz. The operation is simple where the signal from a microphone is amplified to form a modulation input of a variable-frequency crystal oscillator. The oscillator frequeney, around 24MHz, is multiplied in two stages, first a tripler. .. then a doubler to 144MHz. The resulting signal is amplified through several stages before being fed to an antenna. Short form kit contains components and PCB. It's miles ahead of previous models! Our new Light Chaser is low in cost, easy to build, incredibly flexible and it's designed with safety in mind. Providing 6 different chasing patterns, 8 speeds, an enhanced front-panel monitor display and the ability to run lamps to a total of 2400 watts. Whenthe design was first conceived by the our R & D Department safety was considered paramount, so it was decided the best way to achieve this was to build a 'dedicated' chaser. This also allows many more functions to be incorporated without getting into complex construction techniques. Comes complete (full form) , riqht down to the last bolt! Cat K-6010 s59so Cat K-3 161 sgg Short Form Kit: Contains PCB & Components Incredibly Small! With BONUS Christmas Chip! FM Wireless Microphone Melody Door Bell This one is great! The FM Wireless Microphone is small enough to be inserted into a matchbox, can be tuned to operate at around 90MHz (On your FM receiver), incredibly stable, extremely sensitive circuitry and relatively easy to build . It's fantastic! You can use it as a bug (when you 're playing around) or even as a link between, say, workshop and house, etc. Comes as a short form kit with components and PCB. Also includes batteries. Put an end to that boring old doorbell and build yourself the incredible Melody Door Bell. You can select between 3 instruments and any one of 16 melodies ... or even a different melody each time the bell is rung. Kit comes complete including housing and pre-punched, silkscreened panel. It's easy to assemble and runs on 2 x AA batteries that will last for ages. Cat K-2726 Cat K-5006 s1&ss on1v s49ss 8,(-- CHRISTMAS BONUS: Buy this month and you'll Qet an extra chip just brimming with great Christmas tunes! Just send us proof of purchase and we II post ii to you .. . FREE! Communications On & Between Bikes! FM Radio Intercom For Motor Bikes This has to be the best device for motorcycles since they replaced horseshoes with wheels! A true FM intercom which allows communication between passenger and rider as well as between bikes. Not only that, but it also doubles as an FM receiver for your favourite radio station. The transmitter and receiver are housed in a small case which fits in the jacket pocket. The speakers and microphones are fitted in the helmet. As well , the microphone is voice activated to save switching. Beware though, it is not easy to build and is best tackled by someone with a sound knowledge of kit construction. Comes complete - ready to assemble with all components, board, mics, speakers and case. Powered by three penlight batteries (not included). Cat K-6020 1-------NEW KITS SOON TOBE RELEASED- -- VK Powermate 25 The perfect kit for amateurs with all the grunt you need the get the most out of your shack. A high power 13.8DC supply giving a huge 25 amp continuous current rating with a peak of 35 amps. It's capable of running transmitters and amplifiers in the 100150W class. And it's fully protected with both foldback current limiting and an over voltage crowbar circuit. Cat K-3210 Universal UHF Remote Control Switch It's easy to build and can be used for switching security systems, lights, doors ... almost anything you can think of! The kit consists of a 30mHz receiver, decoder IC and output relay driver on a single board. Kit comes complete. With Department Of Communications (DOC) approved transmitter! Cat K-3258 Short Form Only: Includes PCB and Components --- The Widest Range And Best Prices On.... SIIOrTl'O~M 1(/ts & kiT BiTs Here's a great way to get that project you've thinking about . .. up and running. Shortform kits which can easily be adapted to fit that special application you've had in mind, or you can build them as they were intended. All come with instructions and PCB's, some have complete hardware including cases, heatsinks, etc. But there are no components. Hurry stocks are limited! HF Transceiver A great one for the amateur! Comes complete with .... • Counter PCB • Main PCB • Front and Rear Panel • Heatsink and plate • Instructions s499s Cat K-9528 Comes complete with ... • Booster PCB • Filter PCB • Front and Rear panels • Heatsink and cover • Instructions A remote control for the TV, CD, VCR, mains powered appliances, etc. etc. Can control up to 8 functions. You get.... • Receiver PCB's (part A & B) • Receiver front panel • Transmitter front panel Value Plus! s39 95 It's A Bargain! PCB Pack ONLY sgg Series 200 Amplifier It was one of our most popular kits and now you've got the opportunity to build it the way you wanted. Comes with .. . • Main PCB • Control PCB • Front and Rear panels • Top and Bottom plates • Brackets to hold Caps and power supply • Instructions Cat K-9500 8 Channel lnfrared Remote Controller iZ;;~i;i~~~~PCB's (Part A & B) 200W HF Linear Amplifier Cat K-9529 Transmitter And Receiver! Bargain! s129 2L~~ rt'JU!J PHONES SECURITY AUDIO COMPUTERS Here's a fantastic buy that makes great sense for the bits box. Pack come with 10 or more assorted PCB's. there are all sorts and sizes from small to large. There are no instructions with these but you'll find plenty of useful and time saving applications. At this great low price you'd pay for them is you only used one! Cat K- Extra Value! 9553 s129s Available through Mail Orders or, order through your nearest Dick Smith Electronics Store. AND THERE ARE PLENTY MOREi Description Cat No. Fluro Starter Musicolour Mk4 Deluxe Car Alarm Car Alarm Mk2 Negative Ion Generator Home Alarm lnfrared Red Controller lnfrared Red Remote Switch 60 Watt Mosfet Amp Module RLC Bridge Audio Oscillator Graphic Equaliser Low Cost Amp I/R Stereo Head Phones UHF FM Power Amplifier K-9501 K-9502 K-9503 K-9504 K-9505 K-9506 K-9507 K-9508 K-9509 K-9510 K-9511 K-9514 K-9512 K-9516 K-9519 Price Description $0.99 $19.95 $9.95 $4.99 $5.99 $19.95 $9.95 $9.95 $19.95 $2.99 $2.99 $19.95 $19.95 $9.95 $12.50 VHF Gasfet Pre-amp UHF Wattmeter VHF Power Supply RF Attenuator Box 6 Mir Booster Amplifer Radio Direction Finder Signal Tracer/Bench Amp Mega Fast Charger Morse RTTY Decoder Meter 200uA (No Panel) Pre-punched extruded case Heatsink & Cover Suit Assorted Heatsinks & Brackets Heatsinks suit 2 x To-3 Plastic cases suit V2 200 Decodes Cat No. K-9523 K-9524 K-9525 K-9527 K-9530 K-9531 K-9536 K-9538 K-9541 K-9550 K-9552 K-9554 K-9555 K-9557 K-9558 Price $9.95 $5.99 $39.95 $29.95 $29.95 $19.95 $8.95 $5.95 $19.95 $12.95 $9.95 $39.95 $19.95 $5.95 $2.99 Some components for these kits may not be available from Dick Smith Electronics stores. So you may have to source them elsewhere. .. or who knows(?), they may be hanging around in your workshop right now! • NSW • Albury 21 6399 • Bankstown Square 707 4688 • ·B1acktown 671 7722 • Campbelllown {046)27 2199 • Chatswood, Chase 411 1955 • Ch ullora 642 8922 • Gore Hill 439 5311 • Gosford 25 0235 • Hornsby 477 6633 • Hurstville 580 8622 • Liverpool 600 9888 • Maitland 33 7866 • Miranda 525 2722 • Newcastle 61 1896 • North Ryde 878 3855 • Parramatta 689 2188 • Penrith (047)32 3400 • Railway Square 211 3777 • Sydney City 267 9111 • Tamworth 661711 • Warringah Mall 9050441 • Wollongong 283800• ACT• Fyshwick80 4944 •VIC• Ballarat 31 5433 • Belmont 43 8804 • Bendigo 43 0388 • Box Hill 890 0699 • Coburg (03) 383 4455 • Dandenong 794 9377 • East Brighton 592 2366 • Essendon 379 744:4 • Footscray 689 2055 • Frankston 783 9144 • Geelong 232 711 • Melbourne City 326 6088 • Richmond 428 1614 • Ringwood 879 5338 • Spnngvale 547 0522 •OLD• Brisbane City 229 9377 • 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 232 1200 • Beverley 3471900 • St. Marys 277 8977 • Elizabeth 255 6099• Enfield 2606088 •WA• Cannington 451 8666• Fremantle 335 9733 • North Perth 328 6944 • Perth City 481 3261 • Midland 250 1460 • TAS • Hobart 31 0800 •NT• Stuart Park 811977 ORDER BY PHONI! TOLL FREE (008) 22 H10 FORDS XPRESS HOUR Dl!SPATCH .,DickSmith Electronics-Still FullorSurprises' Easy to build UIIF remote sMtch UHF remote switches can be tricky to build and align. Not this one. It comes with a ready made transmitter so all you have to do is assemble and tune the receiver. By GREG SWAIN One of the main aims in designing this new UHF Remote Control Switch was to make it as easy to build as possible. Most people will use it to switch a car burglar alarm on and off but it can also be used with house alarms or for switching mains appliances. When installed in a car, it will have a range of about 10 metres, depending upon the degree of shielding by the car body and the provision of an antenna. 46 SILICON CHIP Apart from its obvious convenience, remote switching also offers improved security and eliminates exit and entry delays. There is no need for hidden switches inside the car and all sensors can now be wired to the instant trip inputs of the alarm. Malcing it easy Remote control switches have been described before but all required the constructor to build and align both the transmitter and the receiver. That's where the problems started. Many constructors find it difficult to set the transmitter frequency correctly and then match it with the receiver, particularly if they don't have access to a frequency meter. The way around this problem was obvious - use a ready made transmitter that could be supplied as part of the kit. This has several advantages: (1). It eliminates the fiddly task of building and tuning the transmitter; (2). It eliminates a source of possible uncertainty if problems are encountered; and (3). It ensures that the transmitter is tuned to the correct frequency (304MHz). To ensure that the transmitter is .---------------------------------+8.5V, 820!] 1M RF AMPLIFIER 150k Q3 PN3563 1M E .01I .,. L2 : 1.66T, 0.8mm ENAMELLED COPPER WIRE CW ON 5mm DIA FORMER SUPER REGENERATIVE DETECTOR AMPLIFIER 39k 2.2 BP* +4.25V ~------------+B.5V WIRE ACCORDING TO TRANSMITTER CODE 270k 10M t I R.ELAY 120n MIN 8.2k 16 ~ Dl-'-----"An LED1 A 14 RELAY DRIVER 10 390k +vs .,. 02 1N4002 +VSD---N-+-'""""' 12V VIEWED FROM BELOW 820!:l + -VS°"]_ .,. 390!:l POWER SUPPLY 10I 100k UHF CAR ALARM SWITCH .,. Fig.1: the incoming RF signal is amplified by Qt and detected by Q2. IC1a-IC1d amplify and square up the detected signal which is then fed to decoder stage IC2. When the correct code is received, pin 11 of IC2 goes high and triggers the output stage (latch IC3a and relay driver transistor Q4). always on frequency, the LC tuned circuit used in previous designs has been scrapped and replaced by a SAW (surface acoustic wave) filter which is precisely tuned to 304MHz. This eliminates the need for transmitter alignment and means that there is very little drift due to temperature variations. Another advantage of this transmitter is that it automatically switches off after about 10 seconds if the button is accidentally held down. As well as saving batteries, this feature is now also a DOTC (Department of Transport & Communications) requirement. The transmitter is supplied in a plastic keyring style case and is powered from a 12V lighter battery. A red LED flashes when the on/off button is pressed. Because the transmitter comes ready made, all you have to do is assemble and tune the receiver. There's just one adjustment to make and that's to a small trimmer capacitor on the receiver PCB. In practice, you simply activate the transmitter and adjust the trimmer until the receiver responds (ie, the relay triggers). Receiver circuit Fig.1 shows the circuit details for the receiver. It can be broadly divided into four sections: an RF amplifier and detector stage (Ql & QZ), an amplifier and comparator stage (ICla-lCld), decoder IC2, and a latch and relay driver circuit (IC3 & Q4). When the transmitter button is pressed, a 9-bit code word is broadcast as bursts of 304MHz oscillation. This signal is picked up by inductor L1 which forms a tuned circuit with the 22pF and 8.2pF DECEMBER1989 47 When mounting the parts on the PCB, keep all leads as short as possible, particularly around RF stages Q1 and Q2. The trimmer capacitor (VC1) must be installed with its flat side towards coil L3 (see Fig.2). We soldered the ICs directly to the PCB but you can use sockets if you wish. capacitors. The signal is then coupled to the base of Ql via a 3.3pF capacitor. Ql functions as an RF amplifier stage with bias supplied by the 8200 and 1800 resistors. The amplified signal appears across 12 in Ql 's collector circuit and is coupled to super-regenerative detector stage Q2. The circuitry associated with Q2 is actually both an RF oscillator and a quench oscillator. The RF oscillator comprises Q2, 13, TCl and the 5.6pF, 220pF, 33pF and 2.2pF capacitors. In practice, TCl is adjusted so that the RF oscillator runs at the transmitter frequency (ie, 304MHz). The quench oscillator includes 14, a 6.8k0 resistor and a 390pF capacitor at the emitter of Q2. Its function is to ensure that RF oscillation does not occur in the absence of an input signal. Q3 is wired as a diode. It forms part of the bias network for Q2 and provides temperature compensation for this stage. When a coded input signal is received, Q2 oscillates at 304MHz and the detected signal appears 48 SILICON CHIP across the 6.BkO resistor. This signal is then applied to a low pass filter consisting of a 1.5k0 resistor and a .OlµF capacitor which removes the 304MHz RF signal but not the pulse modulation. The resulting pulse signal is ACcoupled via a 2.2µF capacitor to ICla which is a non-inverting op amp stage with a gain of about 27. From there, the amplified signal is fed to inverting op amp stage ICl b which has a gain of 18. IClc is wired as a Schmitt trigger. It squares up the amplified signal from ICl b and then feeds it to pin 9 of IC2 via voltage follower stage ICld. IC2 is an MC145028 trinary decoder and is used to decode the 9-bit pulse signal generated by an MC145026 encoder chip in the transmitter. It has nine tri-state address inputs (A1-A9) which are connected to correspond to the transmitter code. These address inputs can be tied high, low or left open circuit. In this project however, the A1-A8 address inputs can only be tied low or left open circuit, while A9 is permanently tied low. This simplifies programming but reduces the number of coding options from 13,122 to 256. This is quite adequate for most applications but there's really nothing to stop you from increasing the odds by tying some of the A1-A8 inputs high. We'll talk more about the coding later on. When IC2 detects a valid code from the transmitter, its output at pin 11 switches high. Just how the. circuit operates from this point on depends on where you install the 8.2k0 resistor in series with the base of relay driver transistor Q4. If the resistor is installed in position AA, then Q3 is driven by latch circuit IC3. IC3 is a D-type flipflop and is wired to change state whenever it receives a clock pulse from IC2. When power is first applied, pin 4 (reset) of IC3 is momentarily pulled high by the lµF capacitor. This sets Q (pin 1) low which means that Q4 is off. When the transmitter button is pressed, IC3 is clocked by the high on pin 11 of IC2. Thus, the Q output switches high and turns on Q4 and the relay. On the next press of the transmitter button, the Q output I ULE01 t, • • ~ •• 1. POLYESTER & CERAMIC CAPACITORS I RELAY • □ □ □ □ □ □ □ □ □ □ □ INC .-:--NO ◄ No. 3 2 1 1 1 1 1 1 1 1 2 Value 0 .1µ,F .01 µ,F .022µ,F 390pF 220pF 33pF 22pF 8.2pF 5.6pF 3 .3pF 2.2pF IEC 1 OOn 10n 22n 390p 220p 33p 22p 8p2 5p6 3p3 2p2 EIA 104 103 223 391 221 33 22 8.2 5.6 3.3 2.2 Fig.2: the 8.2k0 resistor near IC3 goes in position AA if you want the relay to latch and in position BB if you want the relay to turn only only while the transmitter button is pressed. RESISTORS □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ □ No. 1 2 1 1 2 3 1 2 1 1 2 1 1 2 1 1 1 Value 10MO 1MO 390k0 270k0 150k0 100k0 56k0 39k0 27k0 22k0 8.2k0 6.8k0 1.5k0 8200 3900 1800 1000 switches low again and the relay turns off. This means that RLYl is alternately latched on and off for each press of the transmitter button. LED 1 indicates when the relay is on. Now assume that the 8.2k0 resistor is installed in position BB. In this case, the latch circuit (IC3) is bypassed and Q3 is driven by the output of IC2. This means that Q4 is only on while ever the transmitter 4-Band Code brown black blue gold brown black green gold orange white yellow gold red violet yellow gold not applicable brown black yellow gold green blue orange gold not applicable red violet orange gold not applicable grey red red gold blue grey red gold brown green red gold grey red brown gold orange white brown gold brown grey brown gold brown black brown gold 5-Band Code brown black black green brown brown black black yellow brown orange white black orange brown red violet black orange brown brown green black orange brown brown black black orange brown green blue black red brown orange white black red brown red violet black red brown red red black red brown grey red black brown brown blue grey black brown brown brown green black brown brown grey red black black brown orange white black black brown brown grey black black brown brown black black black brown button is held down. As soon as the transmitter button is released, pin 11 of ICZ goes low again and thus Q4 and the relay turn off. Power for the circuit is derived from a 12V battery via a 78L05 3-terminal regulator. The two resistors connected to the GND terminal of the regulator jack up the output voltage to + 8.5V while the 10µ,F capacitor on the regulator output provides supply line filtering. Finally, a half supply rail ( + 4.25V) is derived from a voltage divider network consisting of two lOOkO resistors. This + 4.25V rail is used to bias the non-inverting inputs of ICla, ICl b & IClc. Construction This project was developed by Dick Smith Electronics and is DECEMBER 1989 49 ;; L3 is the only coil that you have to wind yourself. It is made by winding 1 % turns of 0.8mm enamelled copper wire on a 5mm former. Scrape away the enamel coating from the leads before soldering them to the PCB. available as a complete kit (see panel). Construction is straightforward, with all parts mounted on two printed circuit boards. The main board is coded ZA-1518 and carries all parts except for the relay, the LED and a 3300 resistor. These remaining few components are all mounted on a separate small relay PCB. Fig.2 shows how the parts are installed on the main PCB. The order of assembly is unimportant but we suggest that you install the wire links first and then move on to the resistors and capacitors. After that, you can install the diodes, transistors and !Cs. Note that the 22kQ, 39kQ and 150kQ resistors in the base bias circuit of Q2 must be 1 % metal film types. Install the 8.2kQ resistor in position AA if you want the relay to latch on and in position BB if you want the relay to turn on only while the transmitter button is held down. Keep all leads as short as possible when installing the parts on the PCB. This particularly applies to those parts in the RF sections of the circuit (around Ql, Q2 & Q3). Cut the collector lead of Q3 flush with its body before installing it on the board. The coils can now be installed on the PCB. You don't have to worry about Ll since it forms part of the PCB pattern. 12 (4.7µH) and L4 (2.2µH) are supplied pre-wound and should be installed on the PCB using minimum lead length. 13 is made by close winding 1 2/3 turns of 0.8mm enamelled copper wire on a 5mm former (supplied with the kit). Remove the former after winding on the turns, then mount the coil by pushing it down onto the PCB as far as it will go [see photo). Scrape away the enamel coating from the leads with a sharp knife before soldering them to the board. Assembly of the main board can now be completed by installing the terminal block and the trimmer capacitor. Install the trimmer capacitor so that its flat side goes towards 13 (ie, the earthy terminal connects to the 5.6pF capacitor). Relay board The relay board has been designed to accept two different relays: Here's the location of the decoder address pins on the main receiver board. The prototype was coded by tying A1-A4 and A6 low, and leaving A5, A7 and A8 open circuit (see Fig.3). ◄ 50 SILICON CHIP Left: here's how it all fits in the case. The main board is mounted on the lid on 15mm threaded spacers while the relay board is mounted low at one end of the case on a single 6mm spacer. . .. l ~ •' . s:,: , r,. .~ A7 ' .• -~ ~· ., , A1 Fig.3: the transmitter and the receiver are coded by tying selected A1-A8 address pins low or by leaving them open circuit. The transmitter (left) is coded by cutting tracks while the receiver is coded by linking address pins to the earth track. An example code is shown here but you should choose your own code. either the DSE Cat. S-7120 relay rated at 2 amps or the S-7125 rated at 5 amps. The S-7120 will be supplied as standard with the kit but be sure to substitute the S-7125 if the load to be switched draws more than 2 amps, otherwise the relay's contacts will burn out. Fig.2 shows the assembly details for the relay board. Install the relay first, then mount the 3300 resistor and the 3mm LED. Note that the LED is mounted on the back of the board (see photo) and should be stood off the board by about 5mm so that it will protrude through the side of the case. Don't trim off the excess leads at this stage - you may need to adjust the height of the LED later on. Coding The transmitter and receiver must both be identically coded before they can be tested. If you don't use the same code for both, the project will not work. You program in the code you want by simply tying each Al-AB address pin low (ie, to ground) or by leaving it open circuit (0/C). For example, you could tie A1-A4 low, leave A5 0/C, tie A6 low and leave A7-AB 0/C. It's a good idea to write your selected code down on a piece of paper before you actually start making connections. As supplied, the transmitter has the Al-AB address pins of the encoder IC all tied low. Fig.3 shows the locations of these address pins on the copper side of the PCB. They correspond to pins 1-7 & 9 of the IC. Pin 10 (A9) is permanently tied low, as is pin 8 (which is a supply pin). To code the transmitter, first undo the self-tapping screw that holds the case together and remove the PCB (careful - don't lose the little plastic switch lever that sits in the lid). It's now simply a matter of cutting selected tracks between the address pins and the ground track to program in your selected code. The Al-AB address pins on the receiver PCB can now be connected to match the transmitter code see Fig.3. Unlike the transmitter, Al-AB on the receiver are all initially 0/C. They can be tied low by bridging them to the adjacent ground track using a wire link. As mentioned previously, there Where to buy the kit A complete kit of parts for this project is available from Dick Smith Electronics stores or by mail order from PO Box 321, North Ryde, NSW 2113. Phone (02) 888 21 05. The kit comes complete and includes the transmitter, a pre-punched front panel, and a front panel label. The price is $79.95 plus $4.50 p&p. Quote Cat. K3257 when ordering. Note: copyright of the PCB artworks associated with this project are retained by Dick Smith Electronics. This close-up view shows the transmitter address pins. Initially, the A1-A8 address pins are all tied low, so it's simply a matter of cutting selected tracks. The transmitter time-out feature can be disabled to allow receiver adjustments by shorting the 4 7µF electrolytic capacitor. are some 256 possible codes to choose from but this can be increased dramatically if you elect to tie one or two of the address pins high. This can be done by installing small insulated links on the back of the board. Be careful you don't install a short between the positive and ground rails of the battery, otherwise nothing will work. Tuning Having completed the coding, you now have to adjust the tuned circuit in the receiver so that it matches DECEMBER1989 51 PARTS LIST 1 Auto Keeper transmitter (from DSE) 1 PCB, code ZA-1518, 130 x 70mm 1 relay PCB, 53 x 26mm 1 plastic case, 160 x 96 x 50mm 1 5mm coil former 1 6-way PCB-mounting terminal block 4 1 5mm tapped spacers plus screws & washers 1 6mm spacer 1 1 9mm x 1/8-inch screw plus nut 1 12V relay, DSE Cat. S-7020 (see text) Semiconductors 3 PN3563 NPN transistors (01 ,02,03) 1 BC337 NPN transistor (04) the transmitter frequency of 304 MHz. The tuning procedure is delightfully simple: • connect your multimeter between pin 7 of ICl and ground, and set it to a low AC voltage range; • connect a 12V DC supply to the main board (both the relay and the LED should remain off when power is applied); • activate the transmitter and adjust VCl for a peak reading on the meter. You will find that the peak is quite sharp so adjust VCl very slowly. (Note: you must use an insulated tool for this job). Alternatively, you can forget about the voltmeter and simply slowly adjust VCl until the relay turns on (don't forget to link the relay board to the main board first). After that, you can get someone else to activate the transmitter at progressively greater distances while you peak VCl for maximum range. By the way, the transmitter timeout feature is a nuisance when making receiver adjustments. It can be easily disabled by shorting out the 47µF electrolytic capacitor near one end of the IC. Final assembly Construction can now be completed by installing the receiver 52 SILICON CHIP 1 LM324 quad op amp (IC1) 1 MC145028 or SC41344 trinary decoder (IC2) 1 ~013 dual D flipflop (IC3) 2 1 N4002 or 1 N4004 diodes (D1 ,D2) 1 78L05 3-terminal regulator 1 3mm red LED (LED 1) Capacitors 2 1 OµF 25VW PC electrolytics 3 2.2µF 25VW bipolar electrolytics 1 1µF 25VW PC electrolytic 2 0. 1µF ceramic 1 0. 1µF polyester 2 .01 µF ceramic 1 .022µF greencap 1 390pF ceramic 1 220pF ceramic 1 33pF ceramic 1 22pF ceramic 1 1 1 2 1 8.2pF ceramic 5.6pF ceramic 3.3pF ceramic 2 .2pF ceramic 4-20pF trimmer capacitor Inductors L2 4.?µH L3 1 % turns 0.8mm tinned copper wire, 5mm dia. L4 2.2µH Resistors (0.25W, 5%) 1 2 1 1 2 3 1 2 1 10MO 1MO 390k0 270k0 150k0 1% 100k0 56k0 39k0 1% 27k0 1 2 1 1 2 1 1 1 22k0 1 % 8.2k0 6.8k0 1.5k0 8200 3900 1800 1000 Lt is part of the pattern on the main PCB. If need be, the range can be increased by soldering a 250mm-long antenna to the centre of the coil. PCBs in the plastic case. The main board is mounted on the lid of the case on 15mm threaded spacers while the relay board is mounted on one end of the case and secured using a single 6mm spacer, machine screw and nut. The lid of the case is supplied pre-punched to take the mounting screws and there is also an access hole for the tuning capacitor so that you can make adjustments with the lid in place. A front-panel label is supplied with the kit and this should be carefully affixed to the lid before the spacers are attached. Note that the relay board is mounted as low down in the case as possible. This is to provide clearance for the main board. You will have to drill holes in the side of the case for the mounting screw and LED, and to provide an exit for the external leads. Finally, if you want greater range (out to about 25 metres in open space or 10 metres in a car), connect a 250mm antenna to the centre tap of coil Ll (see Fig.2). The PCB comes ready-drilled to accept this lead, so making the connection is easy. ~ PC Marketplace Summer Catalog * * * * MOTHERBOARDS DISK DRIVES PRINTERS MONITORS * KEYBOARDS * * POWER SUPPLIES DISK CONTROLLERS * RAM CARDS * 1/0 CARDS * MEMORY CHIPS * CABLES & ACCESSORIES CONTENTS DEAR CUSTOMER WELCOME TO MY FIRST CATALOG. THIS CATALOG EMBRACES A WIDE RANGE OF PC COMPATIBLE PRODUCTS WHICH WE HAVE SOURCED FROM ALL OVER THE WORLD. P.C. MARKETPLACE STAFF HAVE OVER 15 YEARS MAIL ORDER EXPERIENCE, OUR COMPANY MOTTO JS SIMPLE, WE SOURCE THE HIGHEST QUALITY OF PRODUCT BACKED BY A 12 MONTH REPLACEMENT WARRANTY ON OUR CARD LEVEL PRODUCTS AND WE PROVIDE THE HIGHEST LEVEL OF SERVICE. OUR MOTTO OF "SERVICE IS THE DIFFERENCE" SAYS IT ALL ANYWAY HA VE A BROWSE AND SEE IF THERE IS ANYWAY WE CAN BE OF HELP TO YOU. DONT FORGET THAT JUST BECAUSE IT IS NOT IN HERE DOESNT MEAN WE DONT STOCK IT OR CANT SOURCE IT FOR YOU. s;fZPON Computer cases and power supplies ...... 1 Motherboards .............................................. 2 Motherboards 386 ...................................... 3 Disk controllers ·································"········ 4 Diskdrives and Adapters ............................ 5 Keyboards, Drive cases and frames ........ 6 PHIL GLEESON DIRECTOR Mice .............................................................. 7 1/0 and Development cards ...................... 8 HOW TO ORDER 1. BY PHONE USE YOU BANKCARD, VISA OR MASTERCARD SIMPLY RING US AND QUOTE YOUR CREDIT CARD NUMBER, EXPIRY DATE AND YOUR HOME ADDRESS AND THE DELIVERY ADDRESS (NO P.O. BOXES) 2. BY FAX USING YOUR CREDIT CARD FAX WITH INFORMATION AS BY 1. ABOVE 3. BYMAIL USING CREDIT CARD AS PER 1. & 2. ABOVE BY CHEQUE BY MONEY ORDER BY ORDER FORM FROM GOVT. DEPTS AND APPROVED ORGINISATIONS. 4. 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MUST BE PREPAID MOST ITEMS CARRY A 14 DAY MONEY BACK GUARANTEE (IBIS DOESNT APPLY TO ANY FREIGHT CHARGES) • SERVICE /S THE DIFFERENCE• (02) 418 6711 COMPUTER CASES and POWER SUPPLIES MAXI-TOWER CASE WITH 250W XT CASES POWER SUPPLY Will fit AT/386 Baby or Full (standard) size motherboards Space saving floor-mount case Metal housing chassis Anti-static coated plastic face plate Back plate with 8 expansion slots Switches for Turbo and Reset Indicator lights for Power, Turbo mode, Hard Disk (1&2) operation Keyboard lock with 2-key set Will hold up to a combination of 6 half-height floppy or hard disk drives All necessary hardware included Colour beige 7.35"W x 16.75"D x 25.25" H Weight 34lbs H3520 - $499.00 MIDI-TOWER CASE WITH 200W POWER SUPPLY - Metal housing and chassis - Back plate with 8 expansion slots and power supply mounts - Switches on front panel for power, turbo mode and reset • Indicator for power, turbo mode and 2 x hard disk indicators • Keyboard lock with 2 key set • Will hold 3x5.25" half-height and lx3.5" third-height drives • All necessary hardware included · 7.5"W x 16.15 11 D x 17"H - Weight 24.5Ibs H3521 - $349.00 MINI-TOWER CASE WITH 200W POWER SUPPLY - Metal housing and chassis • Back plate with 8 expansion slots and power supply mounts - Switches on front panel for power, turbo mode and reset - Indicator for power - Keyboard lock with 2 key set • Will hold 2x5.25" half-height and lx3.5" third-height drives - All necessary hardware included - 7.5"wx16.15"Dx12.75"H • Weight 22.5Ibs H3525 - $299.00 Metal housing and chassis Anti static coated plastic face plate Back plate set for 8 expansion card slots and power supply mount Will hold up to 4 drives (HalfHeight) Switch on front panel for turbo & reset Indicator Led's for power, Turbo, Disk Colour grey All necessary hardware included Size 19.S"wx 16.S"d x 5.75"h Weight 17lbs H3510 - $99.00 With H3730 150W Power Supply - $199.00 BABY XT/AT FLIP-TOP Metal housing and chassis Anti-static coated plastic face plate Back plate with 8 expansion slots and power supply mount Switches on front for Turbo mode and Reset Indicator lights for Power, Turbo mode, Hard disk operation Keyboard lock with 2-key set Will hold up to one hard and two floppy drives All necessary hardware is included Colour beige Size 17.125"w x 17"d x 6.S"h Weight 21lbs H3519 - $129.00 With H3733150W Power Supply - $249.00 With H3732 200W Power Sup I -$299.00 PC/XT BABY 150W POWER SUPPLY - L SHAPED • Input <at> 47-63Hz (110/240V switchable) - Output +SV <at> ISA, -SV <at> 0.5A, +12V<at> 5.SA, -12V<at> 0.5A - Plug compatible connectors - Built in fan - Size (6.25"w x 611 d x 611 h) • Weight (5lbs) H3731 - $145.00 PC/XT 150W POWER SUPPLY • Input <at> 47-63Hz (110/240v switchable) • Output +SV<at> ISA, -SV <at> 0.5A, +12V <at>5.5A,-12V<at>0.5A • Plug compatible connectors - Built in fan - Size 5.5"wx9.5"dx4.625"h · Weight 6lbs H3730-$125.00 AT 150W POWER SUPPLY AT 200W POWER SUPPLY - Input 47 - 400Hz (110/240V switchable) - Output +5v <at> ISA, -SV <at> 0.5A, +12v<at> 5.5A, -12v<at> 0.5A - Plug compatible connectors - Built in fan - Size (6.5"1 x 5.88"w x 6"h) • Weight - (6Ibs) - Input 47 -400Hz (110/220V switchable) - Output +Sv<at> 20A, -SV<at> 0.5A, +12v<at> SA, -12v<at> 0.SA • Plug compatible connectors • Builtinfan • Size (6.5"1 x 5.88"w x 6"h) • Weight (6lbs) H3733 - $149.00 H3732-$199.00 • QUALITY COMPONENTS• COMPETITIVE PRICING• (02) 418 671 1 1 PC/XT/AT COMPATIBLE MOTHERBOARDS XT 1MB 12MHz TURBO XT TURBO 10MHz MOTHERBOARD MOTHERBOARD V20 processor Can be expanded to 256k, 512k, 640k or lmb Uses combinations of 414256, 41464 and 41256 4.77 or 12MHz hardware or keyboard selectable operation Front panel LED indicators supported Eight expansion slots Legal BIOS ROMs included 8087 maths co-processor, capability NortonSiratingof2.5 Size 8.5" x 8.5" Weight I.libs $ _ 129 00 Expandable to 640K RAM using 4164, 41256 & 41464 120ns chips 4.77 or 10MHz hardware or keyboard selectable operation Front panel LED indicators supported Eight expansion bus slots Legal BOIS ROMs included 8087-1 Math co-processor capability Performs at an average speed of 100% faster than the original IBM PC/XT Norton SI rating of 2.0 Size 12" x 8.5" Weight 1.75lbs $149.00 M5500- XT 1MB 12MHz TURBO MOTHERBOARD M5502 - XT TURBO 10MHz MOTHERBOARD AT 12MHz 80286 MOTHERBOARD AT COMPATIBLE 16MHz 80286 NEAT MOTHERBOARD Expandable to 1MB RAM using 256K DRAM chips Expandable to 4MB RAM using 1MB DRAM chips Expandable to 2.5MB RAM using a combination of 256K and 1MB DRAM chips 8 or 12MHz hardware or keyboard selectable operation Front panel LED Indicators supported Six 16-bit and two 8-bit expansion bus slots AMI BIOS ROMs included Zero wait state Selectable RAM chips speed (80 or 100 nanosecond) 80287-8 Math co-processor capability Norton SI rating of 13.7 Size 13" x 8.75" Weight 2.25lbs $449 •OO M5505-AT 12MHz 80286 MOTHERBOARD 2 Expandable to 1MB RAM using 256K DRAM chips or 4MB using 1MB DRAM chips Additional 1MB with 256K DRAM SIPs or 4MB with 1MB DRAM SIPs for a total of 8MB 8/12 or 8116MHz hardware or keyboard selectable Front panel LED indicators supported Six 16-blt and two 8-bit expansion bus slots AMI BIOS ROMs included Supports all NEAT functions including shadow RAM, EMS 4.0, • RAM re-mapping, selectable wait states, etc. 80287-10 Math co-processor capability Norton SI rating of 15.6 WAS $799 OO Size 13" x 8.5" • Weight2.25lbs NEW PRICE $649.00 M5510-AT COMPATIBLE 16MHz 80286 NEAT MOTHERBOARD • SERVICE /S THE DIFFERENCE• (02) 418 6711 386 COMPATIBLE MOTHERBOARDS 386 20MHz and 25MHz MOTHERBOARDS - 20MHz Landmark speed 28MHz 25MHz Landmark speed 33MHz Intel 80386 CPU Socket for 80387 Math co-processor 32 bit BUS System, 1MB or 640K on board memory Build-in speaker attachment Battery backup for CMOS Configuration table and real time clock Keyboard controller and attachment 7 Channel DMA 16 Level interrupts 3 Programmable timers 8 system expansion 1/0 slots: 5 with a 36 pin and a 62 pin expansion slot with only the 62 pin expansion slots 1 with two 62 expansion slots The 80386 baby motherboards are available in either 20MHz or 25MHz versions. The 80386 motherboards fit into anXT, AT or baby AT chassis so that the boards deliver 386 power/performance and AT compatibility in an XT footprint size. The motherboards are ideally suited for a variety of applications including Multiuser (Unix, Xenix, PCMOS),Networking (Novell,3-Com), CAD applications (Autocad) and Multitasking (Windows, OS/2, Desqview). The boards feature one 8-bit slot, six 16-bit slots and one 32-bit slot that accommodates the memory card (supplied). Also features 80387 math coprocessor capability. Both motherboards are keyboard switchable betweenlowandhigh speed and 1 or0waitstates. The20MHzboard 386SX 16MHz MOTHERBOARD features a Norton SI rating of 24.2 in the 20MHz mode, while the 25MHz board features a Norton SI rating of 30.25 in the 25MHz mode. AMI BIOS ROMs are included. RAM is mounted on a 32bit expansion card (included) which utilizes (72) 41256-100 256K chips to reach 2 Megabytes A daughterboard is available which accepts (72) 51 l00Op-10 lMeg chips for an additional 8 Megabytes, bringing the total memory of the system to 10 Megabytes. M5514 386 20MHz MOTHERBOARD- $2250.00 M5516 386 25MHz MOTHERBOARD-$2499.00 386 CACHE 20MHz and 25MHzMOTHERBOARDS $1295 00 LandmarkSpeed21MHz Processor: 16Mhz 80386SX • Co-Processor: 80387SX-16MHz (optional) C & T Neat chipset Supports up to 2MB on board (16 x 44256 and 8 x 41256) Supports the Lotus-Intel-Microsoft (LIM) Expanded Memory Spee. (EMS) Version 4.0. Baby Size Main Board Five 16-bit slots, Three 8-bit slots and additional memory slot. Optional memory card: 114MB Memory Card use 44256 DRAM Type. 218MB Memory Card us 41256 or IM DRAM Type. Supports Page/Interleave Mode Using lOOns DRAM Turbo Light and hardware reset connector Speed Selectable by Keyboard or Hardware Power Good Signal on Board · M5528 386SX 16MHz MOTHERBOARD • Processor: 80386-20 or 80386-25. Co-Processor: 80387-20, 80387-25 or Weitek 3167 (Optional) Intel 82385 Cache Controller with 32KB Cache Memory. Flexible Cache Memory Area With 8 Chips & Tech. Chipsets. Three 8-Bit Slots,Four 16-Bit Slots. One 32-Bit slot for: 114MB Memory Card Use 44256 DRAM Type. 218MB Memory Card Use.DRAM Type. 4116MB Memory Card Use Module Type. System Memory Using Page/Interleave Technology. Real Time Clock/Calendar and Battery Backup. Power Good Signal On Board. Baby Size Main Board. Hit Rate: Over 98%. Landmark Speed Test: 20MHz CPU Can Reach To 34MHz 25MHz CPU Can Reach To 43.5MHz MIPS: 20MHz Can Reach To 4.94 (0 Wait) 25MHz Can Reach To 5.75 (1 Wait) BIOS: AMI. M5524 386 CACHE 20MHz MOTHERBOARD -$2499.00 M5526 386 CACHE 25MHz MOTHERBOARD - $3499.00 • QUALITY COMPONENTS• COMPETITIVE PRICING• (02) 418 6711 3 PC/XT/AT COMPATIBLE DISK CONTROLLERS HARD DISK CONTROLLERS FOR XT AND COMPATIBLES • • . . low chip count for increased reliability Half card design for short slots Controls two 5.25" or 3.5" hard disk drives Drive types configurable • Increases hard disk storage capacity by 50% • Controls two 5.25" or 3.5" hard disk drives • Half card design for short slots . SPECIFICATIONS - Host Interface: IBM PC/XT Bus - HDD Interface: ST-412/ST-506 - Heads: 16 Max - Cylinders: 1,024 Max - Encoding: 2nRLL - ECC: 8 bits - Transfer Rate: 7 .5MBits/Sec SPECIFICATIONS - Host Interface: IBM PC/XT Bus HDD Interface: ST-506/ST-412 Heads: 16 Max Cylinders: 1,024 Max Encoding: 11 bits. Data Transfer Rate: 5.0 MB its/Sec M5642- RLL HARD DISK CONTROLLER $179.00 M5641 - HARD DISK CONTROLLER $139.00 HARD DISK CONTROLLER FOR THE AT AND COMPATIBLES Enables the PC/AT to control both 5.25" and 3.5" hard disk drives. ( Controls 5.25" and 3.5" hard disk drives. High-speed, 16-bit data transfers to hard disk file WD1003-WAH compatible. Increases storage capacity of hard disks by 50% Controls two hard disk drives SPECIFICATIONS SPECIFICATIONS - - Host Interface: IBM PC/ATBus HDD Interface: ST-412/ST-506 Heads: 16 Max Cylinders: 1,023 Max Encoding: MFM ECC: 5 bits. HARD FLOPPY CONTROLLER MFM FOR PC/XT HARD FLOPPY CONTROLLER MFM FOR AT Supports UNIX/XENlX, OS/2 and Netware Supports 1.44M, 1.2M, 720K and 360K floppy disk formats Controls either 5.25" or 3.5" hard disk drive Host Data Transfer Rate: 210 KB/Sec. XTHeight Controls two 3.5" or 5.25" hard disk drives. Supports two 360K/720K/1.2M/1.44M floppy disk drives. - Host Interface: IBM PC/XT Bus FDD Interface: FD-55F Hdd Interface: ST-506/ST-412 Heads: 16 Max Cylinders: 1,024 Max Encoding: MFM ECC: 11 bits M5644 - $175.00 Host Interface: IBM PC/AT Bus HDD Interface: ST-506/ST-412 Heads: 16 Max Cylinders: 1,024 Max Encoding: 2n RLL ECC: 11 bits M5647 -$229.00 M5646 - $220.00 SPECIFICATIONS RLL HARD DISK CONTROLLER SPECIFICATIONS - Host Interface: IBM PC/AT Bus FDD Interface:FD-55F HDD Interface: ST-506/ST-412 Heads: 16 Max Cylinders: 1,024 Max Encoding: MFM ECC: 5 bits M5645 - $245.00 SCSI HARD DISK CONTROLLER FOR PC/XT AT DMA channel dispensable for better compatibiltiy Asynchronous SCSI burst transfer rate up to 2 MegaByte/Sec SCSI logical interface for arbitrary SCSI commands to interface any SCSI peripherals Jumper selectable base address for other plug-in card High. reliability with low power consump• tion Coexists with one ST-506 interface hard disk drive and controller in one system. SPECIFICATIONS - Hostlnterface:PC/XT/AT - HDD Interface: SCSI M5670 - $179.00 FOUR FLOPPY DISK ADAPTOR-MULTI FORMAT Controls up to four floppy disk drives. Supports 1.44MB, 1.2MB, 720KB and 360KB formats. Internal or external connection is selectable for the third and fourth disk drives. SPECIFICATIONS - Host Interface: PC/XT/AT Bus. - FDD Interface:FD-55F M5630 - $129.00 4 • SERVICE /S THE DIFFERENCE• (02) 418 6711 ROCTEC EXTERNAL DISK DRIVES ATARI 5.25" 360K/720K 40/80 track switchable external FDD D2918 - $299.00 3.5" 880K external FDD for Amiga 500/1000/2000 D2930 - $249.00 THIRD-HEIGHT 3.5" 720K and 1.44MB DISK DRIVES • • • • • PC/XT PC/XT TOSHIBA 3.5" 720K external FDD for PC (internal/external switchable) 5.25" 360K external FDD for PC (internal/external switchable) 5.25" 360K for Toshiba laptop series D2946 - $299.00 AT D2950 - $299.00 AT D2952 - $329.00 D2948 - $329.00 AMIGA • 5.25" 360K/880K 40/80 track switchable external FDD for Amiga SOO/ 1000/2000 · 360K/720K 40/80 track switchable external FDD for Commodore PC 1 D2932 - $299.00 DISK DRIVES and ADAPTERS Ideal for up-grading your compatible to 3.5" format 720K needs DOS 3.2 or higher 1.44MB needs DOS 3.3 or higher Comes complete with 5.25" mount and cable adaptors Quality Japanese drive construction D2510 3.5" 720K DISK DRIVE- $179.00 D2520 3.5" 1.44MB DISK DRIVE-$199.00 FOUR FLOPPY DISK ADAPTER-360K M5640 - $55.00 D2972 - $399.00 HALF-HEIGHT 5.25" 360K and 1.2MB DISK DRIVES D2610 5.25" 360K DISK DRIVE- $179.00 D2620 5.25" 1.2MB DISK DRIVE - $199.00 CO-EXISTANT DISK ADAPTER Controls two 3.5" or 5.25" floppy disk drives. Supports 1.44MB, 1.2MB, 720KB and 360KB formats Half card design for short slots. External drive connection is optional. SPECIFICATIONS - Host Interface: IBM PC{XT/AT Bus - FDD Interface: FD-55F 5.25" 1.2M for Toshiba laptop series Upgrade your compatible to a second or higher capacity drive • 1.2MB needs compatible controller • Quality Japanese drive construction For PC{JCT/AT or compatibles. It is especially designed for systems which already have a floppy or floppy/ hard disk controller to control the third or/and fourth floppy disk drives. It can also be used to control the first two floppy disk drives in your system. Run up to four 360KB disk drives Includes cable for two internal drives DC37S connector allows for an additional two external drives (external cable not included) complete with manual TOSHIBA 5.25" 1.2MB external FDD for AT (internal/external switchable) 3.5" 1.44MB external FDD for AT (internal/external switchable) D2970 - $349.00 HIGH DENSITY FLOPPY DISK ADAPTER Easy, plug-in installation. · \ Controls two3.S" or 5.25" floppy disk drives. Supports 1.44MB, 1.2MB; 720KB and 360KB formats. Half card design for short slots. SPECIFICATIONS - Host Interface: IBM PC/XT/AT Bus. - FDD Interface: FD-55F. M5643 - $99.00 M5655 - $119.00 • QUALITY COMPONENTS• COMPETITIVE PRICING• (02) 418 6711 5 11.ftll KEYBOARDS, DRIVE CASES and FRAMES ENHANCED XT/AT COMPATIBLE XT/AT KEYBOARD KEYBOARD • 101 Key • Enhanced keyboard layout• Tactile touch keyswitches • 12 Function keys • Ilurninated LED indicators for Nurn Lock, Caps Lock and Scroll Lock • Seperate cursor pad • Low profile design • Switchable between PC/XT or AT• Manual included• Colour beige• Size 19"w x 8"d x l.33"h • • Weight 4.6lbs H3716 - $109.00 • 84 Key • AT style layout • Tactile touch keyswitches • Switch selectable between PC/XT or AT • Illuminated LED indicators for Nurn Lock, Caps Lock and Scroll Lock • Low profile design • Manual included • Colour beige • Size 19.S"w x 7.5"d x l.33"h • Weight 4.6lbs H3715 - $99.00 ENHANCED KEYBOARD WITH SOLAR CALCULATOR • Solar powered calculator offers ease and convenience of use• 101 key • Enhanced keyboard layout• Tactile touch keyswitches • 12 function keys • Illuminated LED indicators for NUM lock, Caps Lock, and Scroll lock • Separate cursor pad • Low profile design • Switchable between PC/XT or AT • Manual included • Color Beige• Size 19.5" x 7.625"D x l.5"H • Weight 3.6lbs H3721 - $149.00 TRANSDATA 3.5" Hard Disk Assembly Fixed Bracket Removable Dirnension:208rnrn x 145mm x 41mm (L x W x H) Dirnension:206rnrn x 117mm x 41mm (L x W x H) Weight :215grn net (w/o hard disk) Material :Plastic Capacity :3.5" half-height disk ST506/412 interface type Transferable to another computer system Convenient for transport and storing Weight :1040grn net Material :Aluminium alloy Keyswitch:Two-position pull CAM switch Buzzer :Pulse sound LED :Power ON (Green) steady: HD R/W (Yellow) trigger :Alarm {Red) pulse Made of heavy duty allurniniurn alloy Security key for locking Warning alarm for indicating wrong operation LEDs for indication R/W operation and system status Easily assembled into the case Includes 1 X H3636 rernoveable bracket H3636-$129.00 H3635 -$179.00 5.25" EXTERNAL DRIVE CASE 5.25" MOUNTING FRAME FOR 3.5" DRIVES Mounts 360k, 1.2mb and tape drives externally Cornes complete with cable D37-D37 H3630 - $85.00 H3638 -$25.00 3.5" EXTERNAL DRIVE CASE Mounts 720k and 1.44mb drives externally Cornes complete with cable D37-D37 With side mounting foot so it uses less deskspace H3631 - $85.00 6 Allows mounting of third height 3.5" drives in 5.25" mount Cornes complete with power cable adaptor and drive adaptor 3.5" DISK DRIVE POWER , -~ ADAPTER The Cl 730 allows connection of standard 3.5" disk drives to the PC, XT and AT power supply connector. - Length (3") C1730 - $5.95 • SERVICE /S THE DIFFERENCE• (02) 418 6711 ID MICE HIREZ BUS MOUSE FOR PC/XT/AT/P 2 COMPUT For XT/ATIPS-2 Total Current l0rnA, CMOS CPU No Power Supply Required Super Tracking Speed: 500mm/sec and up Programmable Resolution: from 22 to 200 DPI Optical Encoder Silicone Rubber Coated Ball Connector:DB-25S (DB-9S Optional) Standard RS-232C Output SMART sm~rw ARE Includes 256 color types Cut, copy and store any size picture Create and store symbols Multiple choice fonts Works with CGA, EGA, Hercules, MGA, PGA and VGA displays Catch and store graphics in other applications Large selection of printers and plotters Lasso-move or cut and paste an irregular shape non-destructively across the screen. SLIDE SHOW SOFTWARE Make a slide show presentation of more than 200 pictures; stored in memory, timed automatically and shown one by one Create slide shows and printer batch files The new LOGIIBCH High Res0lution Mouse is the only mouse designed expressly for today's new generation of high resolution displays, such as EGA, super EGA and VGA. The mouse is ideal for desktop publishing as well as CAD applications. With 320 dots per inch (dpi) resolution (compared with 100 or 200 dpi mice), the LOGIIBCH HIREZ covers the same area on your screen, but uses 62% less desk space to do it. This saves you valuable desk space, and effort. Mouse maneuvers that used to require a sweep of the hand are now reduced to a flick of the wrist. Includes Plus Package software with mouse drivers, text editor, menu building and point-click so'ftware (Lotus 1-2-3). ' Size 3.8"Ix2.7"wxl.06"h - Colour light grey H3925 - WAS $179.00 NOW $149.00 SAVE $30.00 INFRA-RED MOUSE H3905 - $99.00 DYNAMIC MOUSE For XT/ AT/PS-2 An exciting new concept in mouse control has been developed. The Dynamic Mouse 350-1050 DPI resolution gives greater ease and speed in selecting a precise location on the screen. The cordless mouse is a "pointing device" for drawing graphics, moving objects on screen and picking up items simply by moving the mouse on the chosen item and pressing a button. The faster the mouse movement, the greater the distance the cursor moves. Therefore, less hand movement is needed for long moves, yet you still have the precision control to accurately select a point on screen. Switch between Microsoft and PC Mouse Mode Dynamic Resolution: 350-1050 DPI Total Current l0rnA, CMOS CPU No Power Supply Needed Super Tracing Speed: 500mm/sec and Up Optical Encoder Silicon Rubber Coated Ball Connector: DB-9S and 9-25 Pin Adapter Standard RS-232 Output DYNAMIC MENU MAKER SOFTWARE Dynamic Mouse comes with the Dynamic Menu Maker allowing you to design or modify customized menus for virtually any software package, including those which you develop. DYNAMIC SOFTWARE Lets you create stunning graphics which can be merged to show a slide presentation. Capture and enhance graphics created in other applications for more professional presentations. Cut, copy, erase, rotate and store any size picture. Multiple choice fonts. Work with CGA, EGA, VGA, MGA and Hercules Displays. Supports dot matrix and laser printers. Unlike most of the other mice, the cordless mouse uses the latest Infra-Red signal transmission technology. H3915- $119 .00 Comes complete with driver software, test program and menu maker. H3955 INFRA-RED MOUSE- $169.00 MOUSE PAD Cleans, protects and prevents wear on yogr mouse's roller ball. Sensitive, accurate and prevents dirt contamination. Tough non-skid neoprene backing with smooth gliding anti-static plastic coating on top surface. • Size 11 "l x 8.5"w H3900 - $7.50 JOYSTICK Bring your games to life easy and handy to operate H 3940 $29.95 • QUALITY COMPONENTS• COMPETITIVE PRICING• (02) 418 6711 7 lGi PC 1/0 CARDS, DEVELOPMENT CARD MULTI 1/0 WITH CONTROLLER AND GRAPHICS FOR PC/XT Six add-on features using only one slot Text mode: 80 x 25 Graphics mode: 720 x 238 One RS232C serial communication port (expandable to two ports not included} Selectable for CO Ml thru COM4 Game port Real time clock/calendar with replacable battery back-up 5.25" floppy disk drive controller capable of handling up to two 360K drives Parallel printer port - Print spooler software - Manual included M5871 -$229.00 RS232 HALF CARD FOR PC/AT AND COMPATIBLE COMPUTER Fits the difficult to use half card slot or any long slot RS232 card comes with one ready to go serial port Expandable to 2 ports by user (parts for expansion not inc Selectable for CO Ml thru COM4 The user is able to select addresses for ports A abd B as well as interrupt requests Manual Included M5861 FOR XT - $55.00 M5862 FOR AT - $65.00 PROTOTYPE DEVELOPMENT CARD INPUT/OUTPUT CARD FOR PC/ XT COMPUTERS Parallel printer port RS232C serial communication port (expandable by two by user parts for expansion not included} - Selectable for COMl thru COM4 Ability to change interrupt requests on all ports Game port Cables and manual included Real time clock/calendar with replaceable battery back-up and print spooler software included M5860 - $125.00 Designed for the PC add-on card designers as an excellent alternative to pure -N _P _U_T _/_ Q_U _ T_P_U _T_C _A_R_D __F_Q _R_ A _J_----1 breadboard card for developing prototype of add-on cards. 1 The built-in basic circuit can eliminate the heavy labour and time consuming Parallel printer port RS232C serial communication port (expandable to two by user parts for expansion not included} Selectable for COMl thru COM4 Ability to change interrupt requests on all ports Game port Cables and manual included efforts in designing/implementing trhe memory address decoder, 1/0 address decoder, data line buffer and address line buffer. 81/0 write control signals and 8 1/0 read control signals are also provided for easy implementation of the 1/0 R/W registers. Jumper selectable memory FEATURES and 1/0 address sizes Built-in basic circuit for a 37 Pin D type connector ready great deal of time saving for various applications Large breadboard area (3290 holes) for do-it-yourself APPLICATIONS circuits Prototype development kit for All bus signals are buffered, PC add-on cards marked and ready for use - Customized PC add-on cards Independent on-board memory and 1/0 address decoders M5865 - $125.00 MULTI 1/0 WITH FLOPPY DISK ADAPTER The M5879 is a multi 1/0 card with M5885 - $149.00 up to 5 features: One RS232 serial port Optional second RS232 port Games port Real time clock/calendar (can be disabled for AT) Floppy adaptor for 360K,720K, 1.2M & 1.44M Parallel printer port Software manual and cables included SLOT EXTENSION KIT M5879 - $125.00 RS232 1/0 CARDS FOUR PORT AND EIGHT PORT M5840 FOUR PORT ....................................... $199.00 M5842 EIGHT PORT ...................................... $449.00 GAMES CARD TWO PORT M5850 Runs .2 x Joysticks.............................. $29.50 PARALLEL (CENTRONICS) PRINTER PORT CARD Compatiable with PC/XT/AT slots M5890 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 extenal power sources for add on cards on the extension module. The power fuses on M5890 must be removed in this case to disconnect the +SV/ + 12V power supplies from PC All pin-signal assignment of PC-bus are clearly marked on slot No 4 for easy testing/monitoring M5890 - $199.00 M5855 .......... ........................... ....... .................. $24.95 8 • SERVICE /S THE DIFFERENCE• (02) 418 6711 PC RAM AND NETWORKING CARDS 2MB RAM CARD FOR PC/XT/AT 2MB RAM CARD FOR AT Memory expansion for the PC/XT/AT, frees users from the aggravating drawbacks of the 640K MS-DOS limit It fully supports both the Lotus/Intel/ MicrosoftExpanded Memory Specification (EMS) and the AST/Quadram/ Ashton-Tate Enhanced Expanded Memory Specification (EEMS). It allows multi-tasking programs such as DESQview to acess its up to 8 MegaBytes of memory. Software for backfilling conventional memory to 640K is also included. Is a memory expansion board for the AT. Its three purpose design allows it to be used with the Expanded Memory Specifications (EMS) and the Enhanced Expanded Memory Specifications (EEMS) for applications such as Lotus 1-23 and DESQview or to be configured as Extended Memory for use with Xenix, Unix or Microsofts new OS/2 operating system. This diversity gives the user access to the best software available for the AT. FEATURES Supports EMS 4.0. Enhanced Expanded Memory Specification. Up to 2 MByte of expanded memory per card using Inexpensive 41256 dynamic RAM chips. Up to 4 cards are allowed to use in one AT or XT. Supports DESQview, Framework, Lotus 1-2-3 and Symphony. PrintBuffer, TurboDisk Ramdisk and backfilling software provided. FEATURES Supports EMS 4.0. Supports Expanded Memory Specifications, Enhanced Expanded Memory Specifications or Extended Memory Specifications. Up to 2 MBytes of expanded memory per card using inexpensive 41256 dynamic RAM chips. ' Up to 4 cards can be used in an AT. Supports DESQview, Framework, Lotus 1-2-3 and Symphony. PrintBuffer, TurboDisk Ramdisk and Backfilling software provided. M5982 - $245.00 M5981 - $245.00 EXPANSION MEMORY HALF-CARD FOR PC/XT 8 BIT ETHERNET LAN CARD FOR PC/XT/AT NE-1000 compatible NETBIOS compatible Ethernet CSMAICD, IEEE 802.3 protocol Distributed bus, baseband topology 8390 LAN coprocessor Supports ethernet and cheapernet cables 10 Megabits/second transfer rate Supports PC-LAN, MS-NET, Novell Advanced Netware and more Will drive over 300 metres of Cheapernet cable Onboard remote boot ROM socket Includes T-Type BNC connector, utilities diskette and manual. M5920 - $399.00 Expands your system to the maximum 640K (zero-Kon board) Accepts either 64K memory chips (4164) or 256K chips (41256) Eight possible memory configurations ranging from 64K Fits any slot (except slot8 on IBM XT) Manual included M5980 -$99.00 16 BIT ETHERNET LAN CARD FOR AT NE-2000 compatible NETBIOS compatible Ethernet CSMAICD, IEEE 802.3 protocol Distributed bus, baseband topology 8390 LAN coprocessor Supports Ethernet and Cheapernet cables 10 Megabits/second transfer rate Supports PC-LAN, MS-NET, Novells Advanced Netware and more Drives over 300 metres of Cheapei"net cable On board remote' boot ROM socket Includes T-Type BNC connector,.Utilities diskette and manual. M5925-$449 OPTIONS AUTOBOOT ROM FOR M9520 - M5921 - $30.00 AUTOBOOT ROM FOR M5925- M5926- $30.00 50 OHM ETHERNET TERMINATOR- M5928- $9.95 • QUALITY COMPONENTS• COMPETITIVE PRICING• (02) 418 6711 9 Im CABLES and ACCESSORIES PARALLEL PRINTER CABLES 6, 8 And 12 foot lenghts Exceeds EMI/RFI requirements Fully shielded 24AWGwire Moulded, shielded DB25 pin male connector Moulded 36 pin male Centronics connector Colour beige To connect one hard disk (1) C1710 and (1) C1720 are needed. To connect two hard disks (1) C1710 and (2) C1720 are needed. C1710 (34 PIN) - $12.50 C1720 20 PIN) - $9.95 C1520 (8 FOOT STRAIGHT) - $12.50 C1525 (12 FOOT STRAIGHT) - $15.00 C1530 (6 FOOT RIGHT ANGLE) -$15.0 CENTRONICS 36 PIN SHIELDED CABLES For parallel applications, such as switch boxes and printer extension cables (10") length Fully shielded - 24A WG wire Exceeds EMI/RFI requirements Moulded 36 pin Centronics connectors - Colour beige 5.25" DISK DRIVE POWER SPLITTER _-·_ ~ _•--~ - - -' . The Cl 725 is a power splitter for disk ~ drives. It splits a 4 line Molex male into 2 females for general applications (for example 2 disk drives to l power supply) and M5643 - Cable length (27") C34 Internal controller cable PC/XT/AT C1740 - $12.50 3.5"/5.25" DUAL FLOPPY DISK DRIVE CONTROLLER CABLE Compatible with M5640 and M5643 • Cable length (27") C34 Internal controller cable PC/XT/AT Comes fitted with 2x5.25" connectors and 2x3.5" connectors Exceeds EMI/RFI requirements - (10') Length - Fully shielded 24 A WG wire - All solder mount pins are plated pins Moulded, shielded DB25 pin male and female connectors Pins 1-8 and Pin 20 wired Colour beige MACINTOSH+, SE,11 MODEM/ PRINTER CABLE (6' length) Allows connection of standard RS232 modems or serial printers with DB25 connectors to the Macintosh DB25 Male to 8 pin male miniDIN ' C1745- $12.50 EXTERNAL CONTROLLER CABLE PC/XT DC37P External controller cable PC/XT Cable length 48" Fully shielded moulded construction - DC37 plug to DC37 plug C1640 - $19.95 SERIAL CABLE FOR XT/AT (6') Length - Fully shielded Colour grey Moulded DE9 female to DB25 male C1750- $19.95 KEYBOARD EXTENSION CABLE C1645 - $19.95 5 Pin Din M-F · Length (extended) 6' Use with C1810 Move your CPU off your desktop SERIAL 25 PIN SHIELDED CABLES C1805 - $8.95 For serial applications, such as switch boxes and printer/modem extension cables - (10') length - Exceeds EMI/RFI requirements Fully shielded· - 24A WG wire Moulded, shielded DB25 pin male and female connectors Colour beige - All lines connected C1655 (MALE TO MALE) - $19 .95 C1650 (MALE TO FEMALE) - $19.95 10 .,•.: <•~. 5.25" DUAL FLOPPY DISK DRIVE CONTROLLER CABLE Compatible with M5640 C1620 (MALE TO MALE) - $19.95 C1630 (MALE TO FEMALE) - $19.95 • ,. .• · -·--, , C1725 - $5.95 SERIAL PRINTER/ MODEM CABLES · - . / - Length (10") C1545 (MALE TO MALE) - $19.95 C1540 (MALE TO FEMALE) - $19.95 - CONTROL CABLE/HARD DISK DRIVE CABLE FOR XT/AT MONITOR EXTENSION CABLE - DE9M-F - Length 6' Use with C1805 to move CPU off your desktop C1810 - $9.95 • SERVICE /STHE DIFFERENCE• (02) 418 6711 ADAPTERS and TESTERS RS232 GENDER CHANGERS Female gender changer Double-end DE9S (socket) Assembly to interface two DE9P (plug) connections C2040- $9.95 C2050 - $9.95 Male gender changer Double-end DE9P (plug) Assembly to interface two DE9S (socket) connections VGA15 TO XT/AT KEYBOARD TO DE9F PS2ADAPTER ADAPTER Allows use of wide range of AT keyboards on PS2 Moulded construction C2125 - $8.95 These boxes will allow you to design new interfaces or modify old ones. The boxes come complete with (25) 22A WG jumpers and machine tool sockets so you are sure to have a good connection. They are completely selfcontained and are available with either male-male, male-female or female-female DB25 connector c2010 DB25S (socket) to DB25S (socket) - $19.95 C2015 DB25P (plug) to DB25S (socket) - $19.95 C2020 DB25P (plug) to DB25P (plug) - $19.95 RS232 25 PIN TO 9 PIN ADA.PTER Female gender changer Double-end DB25S (socket) Assembly to interface two DB25P (plug) connections C2055 - $9.95 C2041 - $9.95 RS232 BREAKOUT BOXES Male gender changer double-End DB25P (plug) Assembly to interface two DB25S (socket) connections Allows use of EGA monitor with VGA card Moulded construction C2128 - $8.95 MULTI LINK RS232 TESTER AND BREAKOUT BOX Allows cable makers to configure custom cables. The C2200 shows status of lines 2,3,4,6,8,20 and 22 on the DTE and DCE side by ulitizing red/green bicolour LEDs. The C2200 provides you the signal status at a glance (four states: mark, space, clocking and off). Complete cable "breakout" and reconfiguration exists with 24 in-line switches and 54 in-line machine tool sockets. Includes handy carrying case, 10 jumper wires and a device wiring chart. Cable extends 4 inches from side of tester. Connectors; One male DB25 and one female DB25. With the C2200you can easily see if a line is: High (+6 to +25V) bright red led; High (+3 to +6V) dim red led; Low (-6 to -25V) bright green led; low (-3 to-6V) dim green led; Off (-3 to +3V) led off. C2121 D9M-D25F ADAPTER - $9.95 C2220 - $14.95 RS232 INTERFACE CHECK TESTER 3 WAY SWITCHBOXES Ideal for sharing printers and modems or connecting a single printer to up to 3 computers C2120 D9F-D25M ADAPTER - $9.95 The RS232 Mini Tester is designed to test any RS232 (DB25) interface and to help identigy equipment that has failed. The Mini Tester has seven, two colour )eds which indicate the status of TD, RD, RTS, CTS, DSR, CD and DTR. The two colour !eds indicate positive (red) and negitive (green). No extra power is required. Comes with male to female DB25 connectors. C2200 - $49.95 Allows the switching of common input or output to any one of three other devices Use to convert 9 pin (AT) port to 25 pin Use to convert 25 pin to 9 pin RS232 MINI TESTER C2255 ABC D25 SWITCHBOX 3 WAY- $47.50 C2256 ABC CENTRONICS SWITCHBOX 3 WAY-$47.50 The Check Tester will help you avoid expensive repair calls by showing you simple interface problems which you can repair yourself. In seconds, the C2230 will target the status of lines 2,3,4,5,6,8,11,19 and 20. The C2230 comes with male to female DB25 connectors. C2230 - $19.95 RS232 LOOPBACK TESTER The loopback tester is used for diagnostic testing ofRS232 circuits. The tester consists of 4 LED's which monitor lines 2 to 3, 4 to 5, 6 to 20 and 15 to 17. The tester acts as a data verifier by sending data <lack to the transmission device. Comes with male to female DB25 connectors C2210 - $14.95 • QUALITY COMPONENTS• COMPETITIVE PRICING• (02) 418 6711 11 GRAPHICS CARDS and MONITORS MONOCHROME GRAPHICS ADAPTER FOR PC/XT/AT ENHANCED GRAPHICS ADAPTER FOR PC/XT/AT • The M5750 is a monochrome graphics card with parallel printer port and features the following. - Text mode: 80 x 25 - Graphics mode: 720 x 348 • Hercules compatible • Compact half card - Parallel printer interface with transfer rate up to 1000 characters per second • Manual included • The M5755 is an EGA/CGA/ MDAIHGA card featuring the following: - Text mode: 80 x 25 • Graphic mode: 720 x 348 • Reserved video jacks and feature connectors • Light pen interface • 256K Video RAM • Dip switch on back of card allows changing of switch settings without opening case - Displays 16 out of 64 colours • Manual included M5750 • $109.00 M5755 • $225.00 VGA ADAPTER 256K This VGA card is a high resolution display adapter for PC/XT/AT, PS/II Model 30 or compatibles. It supports both analogue and TTL type monitors with VGA, CGA, EGA, MDA andf Hercules modes. Fully compatible with VGA Supports digital and analogue modes including: 640x480 high resolution graphics for PS/II analogue or multifrequency display 360x480 or 320x200 resolution, 256 colours from a palette of 262,144 for analogue monitor capable of operating at 31.5kHz 800x600 high resolution graphics for multi-frequency colour display . 720x540 high-resolution graphic~ for PS/II analogue or multifrequency display 640x350, 640x200 ans 320x200 for 16-colour graphics Powerful, CMOS VLSI chips for increased speed, reliability and compatibilioty 256k on-board memory M5760 - $499.00 COLOUR GRAPHICS ADAPTER FOR IBM PC/XT/AT The M5752 is a colour graphics adapter card capable of operating with either IBM RGB or composite monochrome monitors and features the following: PHILIPS CGA COLOUR MONITOR Picture tube pitch .42 slotted Resolution on RGB 600 lines Features composite, RGB liner and RGB TTL input Stereo amplifer with 2 speakers Ideal for both PC and Amiga computers P6610-$499.00 1+1 YEARWARRANTY 14" FLAT SCREEN MONITOR These new flat screen 14" monitors are ideal for desktop publishing and CAD applications where limited distortion is desired. They feature a compact case with an anti-glare screen, an inverse video switch, a detachable tilt/swivel base, cable and manual. • Input DB9 (TTL) • Bandwith 20MHzx • Horizontal scanning frequency; 18.432kHz • Resolution 1,000 lines (centre) • Character display 80 characters x 25 rows • Size 12.75"W X 12.2"D X 13.6"H · Weight 16lbs P6510 AMBER -$199.00 P6515 WHITE- $199.00 P6520 GREEN -$199.00 MULTI-GRAPHICS CARD Single card can drive either Mono or CGA Monitor Allows CGA software to run on Mono Monitor M5751 • $139.00 Parallel printer port Text modes: 40 x 25 or 80 x 25 Graphic modes; 320 x 200 or 640 x 200 Light pen interface Includes composite video monitor adapter Manual included WE ALSO SELL EGA, VGA AND MULTISYNC MONITORS, PLEASE CALL FOR PRICING. M5752 - $1 t5.00 12 • SERVICE /S THE DIFFERENCE• (02) 418 6711 OLYMPIA PRINTERS OLYMPIA NP80, NP136 AND NP30 DOT MATRIX PRINTERS print line of 13.6" (136 columns at 10 cpi). Draft print speed of 240 cps and 80 cps letter quality. Two printers at the forefront of matrix technology that ensure both letter quality text and high resolution graphics can now be produced on the same machine without having to compromise on quality. NP136 P6725-$999.00 By using the latest 24 pin printhead, high speed letter quality test CaJ\ be printed in a wide range of fonts and pitch sizes easily selected by the operator panel or software. Text can be printed in draft, normal and italic styles and in 10, 12, Condensed, Expanded or Proportional Spacing. lbe AEG Olypmia 24 pin NP matrix printers are compatible with virtually every make of micro-computer and industry standard software. Both Parallel (Centronics compatible) and Serial interfaces are fitted as standard and a large 16Kb buffer means that data can be downloaded into the printer releasing ther host computer. NP30 The LCD display shows the current printer status such as font and pitch selections. The parameter menu is controlled from the operator panel and once set ensures that the printer is ready to go every time it is switched on. The paper parking feature is standard on both machines and allows single sheets to be loaded without having to remove the continuous stationery. An optional sheet feeder (single and dual bin) can befitted to the printer enabling the automatic feeding of cut sheet paper. The NP80-24 is ideal for letters and all documents up to A4 size with its paper capacity of 76.2 to 254mm (3"-10") and maximum print line of 8" (80 columns at IOcpi). Draft print speed of 200 cps and 67 cps letter quality. NP80 P6720 - $799.00 The wider carriage NP136-24 also enables the printing of wider documents and spreadsheets with its paper capacity of76.12 to 406.4mm (3"-16") and maximum THE DESK TOP LASER PRINTER - LASERSTAR 6 The Laserstar 6 heralds a new generation of desk top laser printers. Its compact size enables it to be connected and used with computer systems, even in a confined work space. The unique controller card, developed by AEG Olympia, is compatible to industrial standards. The practical, space-saving design provides a framework for a variety of functions in a laser printer which can be connected to virtually all systems. Automatic single sheet feed, and the choice of face down (in correct sequence) or face up paper ejection. SUMMARY 1.5 Mbyte memory as standard Centronic and RS232 C/V 24 Interfaces Diablo and HP Laserjet + emulations 18 fonts (9 portrait, 9 landscape) GKS vector graphics Enlarge text up to 4 times the height/width Print text in 4 directions on the same page Customized cards to load form APPLICATIONS Text processing High quality graphics Desk Top Publishing Photographs Forms printout Overhead transparencies Bar codes Symbols Envelopes The ability to combine various text fonts with graphics and symbols on paper, overhead transparencies and envelopes make Laserstar 6 an ideal work-station printer. Texts and documents, combining graphics, and even digitized photographs can be printed using Laserstar 6. SPEED Six pages/minute, of changing content, in a quality of a daisywheel printer or typewriter, and the available use of various typestyles within a page. QUITE OPERATION Meets the requirements of a modem office SIMPLE OPERATION Print parameters, one<: installed, are automatically selected every time the machine is turned on. Changing to a different font or print direction is carried out via the control panel. There is even a test key to provide a printout of the current printer status and selected fonts. SIMPLE MAINTENANCE All the consumables are delivered with the Laserstar 6. The clam-type construction ensures that the consumables can be quickly and easily replaced. The :r-.'P30 is an intelligent printer that has a draft speed of 130 cps with logic seeking and bi-directional printing. For important documents, the expectional NLQ mode of 26 cps can be selected and offers a wide reange of typestyles including Italic and Proportional Spacing. The industry standard high quality graphics mode enables the printing of those important graphics and charts. The Centronics compatible interface (an RS232 interface option is available). Epson and IBM compatibility ensure quick and easy connection of the NP30 to virtually all microncomputers and all the leading text and graphics software packages available. With a 4K print buffer, friction feed for single sheets and a built in tractor foruse with continuous paper, the NP30 gives excellent value for money. A single sheet feeder and forms tractor are optionally available for the NP30. 9 Pin head 130 cps print speed 101 • 254 mm paper width· 80 columns at 1/10" Centronics interface Epson and IBM compatible control codes 4K print buffer Self test P6710-$499.00 THE CONTROL PANEL located on the front of the machine, is easy to operate. Paper size, fonts and print direction can be selected. Indicators provide information regarding the machine status, such as ready for use, ON LINE, no paper, no toner, font and page format selection. All print parameters are set and installed by the control panel (LED display). DUAL INTERFACES There are no problems connecting Laserstar 6 to computer systems as parallel (Centronics or Dataproducts) and serial interfaces RS 232 CN 24 are fitted as standard. The interface and correct parameter are selected via the control panel. The current parameters can be recalled into the display at any time. INTERNAL FONTS Being able to select different typestyles and sizes is one of the benefits of a laser printer, and with Laserstar 6 there are 18 typestyles or fonts (9 portrait and 9 landscape). There are four standart text fonts in 10 and 12 pitch, proportional and micro spacing. These fonts can be used in word processing, spreadsheets, etc,. and are compatible with AEG. Olympia daisywheel typestyles. the five typographic fonts are all in proportional spacing. The correspond to HP font card "F', and are supported by Desk Top Publishing software packages. Standard fonts and typpographical fonts. SPECIFICATIONS Speed of 6 pages per minute Warm-up time approx. 45 seconds, first page 20 seconds Resolution of 300 x 300 pixels/inch Single sheet paper feed Paper formats - Automatic paper handling DIN A4, AS, BS (60-90 G/M2) US Letter, Legal, Half Letter, Manual paper feed: Labels transparencies, envelopes. Paper capacity • Paper feed tray: 150 sheets. Memory 1.5 Mbytes (Upgradable to 2 Mb) Interfaces • Parallel (Centronics and Dataproducts compatible) Serial RS 232 CN 24 Graphics - Bit map, GKS Vector graphics Emulations• Diable 630, H-P Laserjet + (in preparation: Epson, IBM Proprlnter, Postscript) Character Sets - 54 National character sets P6730 -$3699.00 For more information on Olympia printers ask for informative brochures. • QUALITY COMPONENTS• COMPETITIVE PRICING• (02) 418 6711 13 E OLYMPIA Model NP30 I t ' . -------~ ' ):::, . ::):::\i,; "'": ' / / '- ·~·«. ,- , Model NPS0-24 \ - Model NP136-24 Laserstar 6 See previous page for full specifications on all printers Monitor For PCs; Simple Stub Filter For Suppressing TV Interference. June 1989: Touch-Lamp Dimmer; Passive Loop Antenna For AM Radios; Universal Temperature Controller; Understanding CRO Probes. July 1989: Exhaust Gas Monitor; Extension for Touch-Lamp Dimmer; Mains Hum Sniffers; Ultrasonic Car Alarm. Au gust 1989: Build A Baby Tower AT Computer; Studio Series 20-Band Stereo Equaliser; Garbage Reminder; Introduction to Stepper Motors. September 1989: 2-Chip Portable AM Stereo Radio; Al'3.rm-Triggered Telephone Dialler; High Or Low Fluid Level Detector; Simple DTMF Encoder. October 1989: Introducing Remote Control; FM Radio Intercom For Motorbikes; 1 Mb Printer Buffer; Installing A Hard Disc in the PC February 1988: 200 Watt Stereo Power Amplifier; Deluxe Car Burglar Alarm ; End of File Indicator for Modems. March 1988: Remote Switch for Car Alarms; Telephone Line Grabber; Endless Loop Tape Player. High Performance FM Antenna; Matchbox Crystal Set; Electronic House Number. November 1988: 120W PA Amplifier Module; Poor Man's Plasma Display; Car Safety Light; How to Quieten the Fan in Your Computer. Aprll 1988: Walkaround Throttle for Model Railroads; pH Meter for Swimming Pools; Slave Flash Trigger; Headphone Amplifier for CD Players. May 1988: Optical Tachometer for Aeromodellers; High Energy Ignition for Cars; Ultrasonic Car Burglar Alarm . June 1988: Stereo Control Preamplifier; Breakerless Ignition For Cars; Mega-Fast Nicad Battery Charger. July 1988: Fitting a Fuel Cut-Off Solenoid; Booster for TV & FM Signals; The Discolight Light Show. August 1988: Remote Chime/Doorbell; High Performance AC Millivoltmeter; Getting the Most Out of Nicad Batteries. September 1988: Hands-Free Speakerphone; Switchmode Charger for December 1988: 120W PA Amplifier; Diesel Sound Generator; Car Antenna/Demister Adaptor; SSB Adaptor for Shortwave Receivers. January 1989: Line Filter for Computers; Proximity Detector for Cars ; How to Service Car Cassette Players. February 1989: Transistor Beta Tester; Minstrel 2-30 Loudspeaker System ; LED Flasher for Model Railways; Lightning & Electronic Appliances . March 1989: LED Message Board ; 32-Band Graphic Equaliser; CD Compressor; Amateur Band FM Receiver. April 1989: Auxiliary Brake Light Flasher; What You Need to Know About Capacitors; Telephone Bell Monitor/ Transmitter. November 1989: Radfax Decoder; Simple FM Bug; Low Cost Analog Multimeter; Floppy Disc Drive Formats & Options . 1 2V Gel Batteries; Vader Voice. October 1988: Stereo FM Transmitter; May 1989: Electronic Pools/Lotto Selector; Synthesised Tom-Tom ; Biofeedback Note: November 198 7 , December 1 98 7 & January 1988 are now sold out. Use this handy form to order your back copies --. ,------- - ------------- - ---- -------- + - - 7 Please send me a back issue for: □ February 1 988 □ March 1 988 □ April 1 988 □ July 1988 □ December 1 988 □ August 1988 □ January 1 989 □ September 1 988 □ February 1 989 □ May 1988 □ October 1988 □ June 1988 □ November 1 988 □ March 1989 □ August 1989 □ April 1989 □ May 1989 September 1 989 □ □ October 1989 □ June 1989 □ July 1989 □ November 1 989 Enclosed is my cheque/money order for $ _ _ _ _ _ _ or please debit my □ Bankcard □ Visa Card □ MasterCard Card No I~ ~ ~ ~ ~~ ~ -- ' - -- ' - ---'--- ' -- ' - - ' - - ' -- ' ----'-~ Price: $A5.00 each (includes postage). Overseas orders add Signature _ _ _ _ _ _ _ _ _ _ Card expiry date_ _ / __ / _ _ $ A 1.00 per issue for postage. NZ & PNG orders are sent by air mail. Name___________________________ (PLEASE PRINT) Detach and mail to: SILICON CHIP PUBLICATIONS Stree.__ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __ PO BOX 139 COLLAROY BEACH NSW 2097 Suburb/tow .__ _ _ _ _ _ _ _ _ _ _ Postcode____ OR FAX: (02) 982 9553 l . I ~------------ -- - -- - - --- ------ - -------- ~ D ECEMBER 1989 69 COMPUTER BITS By JENNIFER BONNITCHA Adding RAM to your computer Software expands to fill the available memory, to paraphrase a familiar adage. If you have a computer, sooner or later you will want or need ·more memory. Adding it is usually a matter of plugging in RAM chips and then resetting the motherboard DIP switches. The story of how the computer shrank in size from that of a room to the silicon chip is now familiar to most computer users. The technology for producing microchips was originally very expensive, so early computer memories were initially small. Computer programs in those "olden days" were designed to OC7 cupy a minimum of memory space. The trend since has been towards more memory and more functions in less space. First there was the integrated circuit (IC), then Large Scale Integration (LSI) and now Very Large Scale Integration (VLSI). Integration in this context means that functions previously located on different chips are now incorporated as part of one microchip. The chip itself is made of a semiconductor, usually silicon, which has been etched and plated. The pattern etched on the surface is that of the integrated circuits. First the pattern is drawn large, generally using computer-aided drafting (CAD), and then reduced in size. The modern computer has electronic circuits which use the binary number system for all operations. The binary system consists only of the digits O (zero) and 1 (one); the "on" state can be defined as 1, the "off" state as 0. 70 SILICON CHIP The smallest part of the binary system is called a bit (Blnary digiT). All information in the computer is stored in bits, however different computers process the information at different rates. Most chips are designed to receive, process and send one bit of information at a time. Eight bits make a byte. Each byte can have 256 different values from 0 through to 255. Data is moved in bytes around the computer system through eight wires known as the parallel data bus or more usually, just the data bus; each wire carries one bit of the 8-bit byte. All bytes used by the computer are stored in a special memory location and each location has a unique address. The Central Processing Unit (CPU) is the "brain" of the computer. The original IBM computer used Intel's 16-bit microprocessor, the 8088. This processor operates internally on 16 bits of data at a time but transfers the data 8 bits at a time to and from the external devices. Memory chips are thus assembled in multiples of 8, plus one extra for parity checking. Thus, while the 8088 is described as having an 8-bit data bus, it is generally considered a 16-bit processor. The AT computer is based on the Intel 80286 which is a true 16-bit processor. Information is transferred 16 bits at a time so the memory chips are installed in multiples of 16 bits with 2 bits for parity checking. Finally, the newer 386 computers have a 32-bit processor which also has RAM on a proprietary memory board. This highly specialised memory contributes significantly to the high performance of the 386. The main memory area of the personal computer is called Random Access Memory (RAM). The CPU is capable of asking for data directly at any address, rather than sequentially locating the information, as is the case with, say, a cassette tape. Adding memory Many users purchase a computer system and then decide to enhance the original hardware. For the majority of users, particularly considering today's memory-hungry applications, the first choice is to add additional memory. Although computer memory has, in fact, several different components, expanding memory generally refers to one type of memory - RAM. Officially, RAM on the IBM PC XT is expandable only to 640K. However with larger amounts of RAM, spreadsheet programs such as Lotus 1-2-3 can have larger worksheets, desktop publishing programs such as Ventura can run the Professional Extension, and integrated .programs such as Excel just take up a lot of memory space. Increased RAM also can be allocated to a "RAM disc" which is a virtual, electronic disc drive. The advantage is that the disc drive, POWER SOCKET PARALLEL PORT FLOPPY DISC CONTROLLER Adding extra memory to your computer is simply a matter of installing additional RAM chips in the sockets on the motherboard. Always use the correct memory chips and be sure to install them the right way around. typically drive E, can be used for the system at the same rate. temporary data storage. It is useful Chip speed is measured in for storing frequently used sections nanoseconds (ns). A nanosecond is of a program, and since it is much one billionth (10 - 9) of a second. faster than conventional mechanOne megahertz (1MHz) is one Jcal disc drives, program execution · million ticks (cycles) of the CPU is considerably faster. clock per second. Thus one clock cycle at 1MHz is equal to 1 microseMemory speed cond or 1,000 nanoseconds. 10MHz is 10 times faster with clock cycles Each computer is designed to use (or windows) of 100ns. RAM chips of a certain minimum XTs manufactured after 1983 speed. Memory specifications are had a processor speed of 4. 77MHz typically described by capacity, and thus a minimum access speed speed and type. While it is possible of 200ns. However, memory chips to substitute slower chips for the then were in the range of 200 to correct type, you then run the risk 300ns. To compensate, a "wait of jeopardising the integrity of the state" was added to make the data moved through the chips. 200ns window twice as wide at Similarly, there is seldom any ad400ns. The fast 386 processors of vantage in purchasing chips which today zoom through work at 25MHz significantly exceed the computer with ticks of the CPU clock only 40 manufacturer's specifications. The nanoseconds long. processor still operates at the same speed, passing information through Speeding up operation of the computer seems to be a neverending story. The latest step is the invention of a special kind of circuit called "cache memory". The circuit monitors information passing between main memory and the processor. Each time the processor sends information to memory, the cache circuit grabs a copy and stores it away. Should the processor again call for the same information, it is delivered at high speed to the processor. When this occurs, the processor experiences no waiting, so the operation is referred to as "zero wait state". If the information is not available, cache memory remains silent and the processor communicates with memory in the usual manner. Typically, the memory cache is measured in increments of 32K and it is generally better to use smaller DECEMBER1989 71 Switch 1 QI 2 3 4 5 6 7 8 ~□ ~□ □□□□□ Position 1 7-8 2 34 5-6 Position Function Amount of memory options installed Always in the off position rather than larger caches. Amongst other reasons, the smaller cache takes less time to fill up. Memory options IBM PCs manufactured prior to 1983 used 16K RAM modules with one module of nine chips always installed at the factory. Thus, the minimum on-board memory for these models was 16K. Memory expansion for these systems was obtained by installing up to three additional kits of 16K each. Each kit contained nine 16K bit chips. PCs manufactured after mid1983 and the PC XTs all use '64K memory chips. Each has four rows of sockets on its system board. The PCs come with a minimum of 64K bytes of memory, which means that up to three additional 64K memory kits can be installed. The XTs have a minimum memory of 128K and can accommodate up to two additional 64K memory kits. Once the system board of the PC or XT is filled, RAM memory can only be expanded by the use of memory adapter cards. Installing three memory kits in your PC raises the amount of on board memory to either 64K or 256K bytes of storage, as the actual 72 96KB 1 □ 0□□ 00001 1 □□□□ 0000 1 128KB 10 0□□ 00001 lo□M □o □ ol 160KB 100□□ 000011 □□□□ 00001 Function Number of 5'/4-inch diskette drives installed Reserved for co-processor Amount of RAM on system board Type of monitor you are using Switch 2 1-2-3-4 5-6-7-8 MEMORY OPTIONS SILICON CHIP D□ □□ ODDI I □□□□ 00001 228KB 1□ 0□□ 00001 1□□□□ 00001 256KB I□ o□ □ oo □ ol lo □□ □ oo □ol 196KB ID Fig.1: the DIP switches on the motherboard must be reset if you install extra RAM. These diagrams show the settings for switches 1 & 2 in the IBM PC but you should always check the manual for your particular machine. amount is dependent on whether 16K or 64K chips are used in the upgrade. Adding 64K memory kits to the XT raises the on-board memory from 128K to 192K or 256K bytes. Once this limit is reached, RAM cards or multifunction boards can increase the XT's memory beyond 256K, usually to the maximum addressable by the DOS operating system - 640K. Although 640K is the minimum required for use in today's memoryhungry environment, for the ATstyle computer, 1Mb or more of memory is not beyond reason, especially when you deal with large spreadsheets or desktop publishing applications. It seems that when/if the OS/2 and UNIX-style multitasking operating systems really come to the fore, computers will require around 2MB of memory just to work, let alone run any applications! Memory is added to the AT system board in 128K increments, up to a maximum of 1.2Mb. The AT memory expansion options include 128K memory expansion option, a 256K memory expansion kit and 512K expansion options. Again, RAM cards or multifunction boards may be added to the system unit to increase memory to 16Mb. Parity As noted above, each row or bank of memory on the PC consists of nine chips. Eight of the chips represent the eight bits in the data byte, while the last chip is used for memory parity checking. This extra bit of information is usually added to each character specifically for error checking purposes. Parity is computed by adding up the number of "1" bits in a data field. An even number of ls would result in a "1" as the parity bit, while an odd number would give a "O". The result of the addition is called the parity checksum, and parity checking is the most basic form of error checking. Should a problem arise, there is a roughly 50% chance the computer will realise this since the parity check bit will not match. Live in fear of the DOS message "Parity Error at 1000:lFOF" since this indicates a defective chip. If you ever do get this dread message, writing down the address will help determine which memory chips are defective. Sockets for the RAM chips are located near the bottom of the system unit. The location is easily identified by the labels on the system board, eg: XT Bank 0, Bank 1, Bank 2 & Bank 3. AT Bank 0, Bank 1. Banks O and 1 already contain chips on older versions of the XT while Banks 2 and 3 on these machines are empty. If only 64K of memory is added, the chips are placed in Bank 3. On the basic AT, Bank O contains 256K and Bank 1 is empty. When you install a chip, note the small notch or dot on one end of the chip. This identifies pin 1. In memory banks, this end always faces the same direction, so make sure the chips you install · do likewise. To install a chip, place it over the corresponding socket then tilt slightly so that one row of pins matches the appropriate holes. This done, gently push the pins on the opposite side into the holes, then push the chip firmly down into the socket. DIP switch settings After installing the additional memory, you must also alter the DIP switches located on the system board below and to the right of the expansion slots. This is to allow the computer to recognise the additonal memory (see Figs.1 & 2). Once the extra memory space on the system board has been filled to capacity (256K on the XT and 512K on the AT), you can add further RAM by installing a RAM or multifunction card. Memory options for the AT, such as the 512K memory expansion card, are inserted into an available slot. Amaximum of five cards may be installed to typically combine parallel and serial interfaces with other features such as additional RAM. We've already mentioned the advantages of the extra RAM and you frequently receive a bonus with these types of boards in the form of extra software which allows the spare memory to be used for tasks such as "print spooling". Thus, print information is stored in the extra RAM and by so doing, main RAM and the rest of the computer is freed to perform other tasks while the slow process of controlling the print functions is performed. ~ Switch I 2 3 4 5 6 7 8 "' of~ lJ □ □ □ □ □ □ Position 2 3-4 5-6 7-8 Function For normal operation is off Co-processor Amount of RAM on system board Type of monitor you are using Number of 5 ¼-inch diskette drives installed Memory options K I □ □□□ ODDO I I □ 0~ coo DO I K IOD□ □ DO DO I 128K 192 256 D.DAUNER ELECTRONIC COMPONENTS WE STOCK A WIDE RANGE OF ELECTRONIC PARTS for • Development • Repair • Radio Amateur • Industrial Electronic • Analog and Digital WHILE STOCKS LAST NEOSID HELIX FILTER for UHF now available COAXIAL RELAY 28VDC $32.00 TRANSMITTER VALVE 5786 $18.00 Come and see. Showroom: 51 Georges Crescent, Georges Hall, NSW 2198 (Behind Caltex Service Station In Blrdwood Road) Phone 724 6982 TRADING HOURS: Monday to Friday 9.00 a.m. to 4.00 p.m. Saturday from 9.00 a.m. to 12.00 noon. * GREAT VALUE AND TECHNOLOGY * COMPUTER PRODUCTS ... AT·4000 Motherboard 12MHz 80286 AT ulg for XT. $489 AT,4000 System 12MHz 512K 101Kbd, 200W, PS etc $1499 ECI VGA ·16 EGA , CGA, HGA modes Card 800x600x16 Res. . $399 AHOOO MB 25MHz 80386 inc 018M 32·bit Mem Exp Board $1989 . $802.06 ECl.fAX for XTIAT . . $399 2S&P $85; FDC $97.2;; 101KBD $88.43; ED·CGMA $99; VGA MON $775; 1.2MB FDD $161.20; 1.44MB FDD $181.35; CASE & 200W PS $207; SAVE 30% OH INDUSTRIAL CONTROL CARDS . . . EC111 6511 2MHz SBC with AID DIA Clk 8at. $336 EC109 6809 CPU 2MHz w/Clk Bat 2 x RS232 Cent 1/F . $304 EC545 Colour Crt (RGB) 16k/4 page SRAM 512 Char . $238 EC·1F124 IND CONTRLR Forth 1D·bit AID, DIA Opto lsol $392 LEDS 3mm & 5mm (Min 1OD/type) ... Red $0.05; Red HB $0.08; Green $0.07; Yellow $0.08; Orange $0.08 DIODES (Min 100/type) . .. IN4001; 1N4004 ; 1N914; 1N4 148 . $0.05 OTHER BITS .. . GAL PAL Programmer - 1 only - WAS $750 . . .. NOW $400 G65SC02·2 . $3.90 G65SC51 ·2 . . $4.00 SRAM Batt B/up Skt - Convert SRAM to non vol . . $19.95 QUALITY DISKETTES_(Pkt of 10, 100% error free , Lltime G/tee) 51/," DSDD 360K . .$ 6.25 51/,"DSHD 1.:/MD .. . ~17.88 3½" DSOO 720K . . $19.75 DSHD 1.44Mb . ... . $39.99 P&P $8.50 PRICES INGL. SALES TAX Fig.2: there's only one DIP switch to worry about on the XT's motherboard. Set positions 3 & 4 as shown to correspond to the amount of on-board memory. 26 Boron St, Sumner Park, Brisbane, Qld 407 4 Ph: (07) 376 2955 Fax: (07) 376 3286 WELLINGTON HZ: Ph: (04) 85 8742 Fax: (04) 82 8850 Ken Curry Managing Director DECEMBER1989 73 Balanced input & output stages for the Studio Series equalisers Have you built the Studio Series Third Octave Equaliser or the Studio Series Half Octave Equaliser? Or do you have a piece of audio gear which could benefit from balanced lines? If so, you'll want this little board which gives balanced input and output stages. Design by JOHN CLARKE When we featured the Studio Series 32-Band Graphic Equaliser in the March and April issues of this year, we were well aware that many users would want to build the unit with balanced inputs and outputs. Here then, is the add-on board we promised in the April issue. If you have to run audio signal cables for long distances, say more than 5 or 6 metres, balanced lines can give a big improvement in the amount of hum and noise in the system. They can also obviate most of the hum problems which occur due to earth loops. What we propose to do in this article is to present a printed circuit board which has balanced inputs and outputs and which can be built in mono or stereo form. We'll show how it is installed in both the mono 32-band equaliser presented in March and April and the stereo 20-band equaliser presented in August and September. After reading this article, it will be fairly obvious how to use this board in other applications, such as adding balanced inputs to a stereo amplifier or say, balanced outputs to a stereo mixer. For the present though, let's just consider the equalisers mentioned above. Now refer to the circuit of Fig.1. Fig; 1 shows two separate circuits, one for balanced inputs and one for balanced outputs. Let's look at the balanced input stage first. Balanced input This view shows the mono version of the balanced input/output board installed in the chassis of the 32-Band Third Octave Equaliser. Note the use of shielded cable for the audio input and output connections. 74 SILICON CHIP The balanced input stage involves a dual op amp, ICla and ICl b. Strictly speaking, the circuit should be called a balanced to unbalanced stage since it effectively converts balanced lines to unbalanced output. Alternatively, you could think of ICl as providing a differential input and a single ended output. The method of connecting the op amps of ICl is a little unusual. ICla is connected as a conventional noninverting amplifier with feedback from the output to the inverting input via R2 and Rl. Since Rl and R2 have equal values, the gain of ICl is 2. I Cl b does double duty. For signals from the output of ICla, it functions as an inverting amplifier with a gain of 1 and so gives an overall gain of - 2. However, for R2 1k R4 1k FIX-A-KIT Kit Repairs - $15 per hour. ~,~:2f,- Normal Rate - $35 per hour. 33 INPUT 3 + 1 33 OUTPUT TO EQUALISER INPUT - 10k .,. ~ '":" i -15V R1 1k 10k No charge for kits that can't be repaired. 3 month Warranty on repairs. Construction - fixed or hourly 1 2 Month Warranty on Manufactured Kits. +15V + LM833 10:r Custom Designing, Manufacturing, Large or Small Quantitites. .,. INPUT FROM EQUALISER OUTPUT i 100k HYCAL .,. BALANCED LINE OUTPUT 10k INSTRUMENTS Design, Manufacture, Repair of Electronic Equipment. (02) 633 5897 Unit 4, 62 Great Western Highway, Parramatta, NSW 2150. BRACKETS SHOW SECOND CHANNEL ICS IF REQUIRED Trading hours: Barn to 3pm Monday to Friday. BALANCED LINE INPUT AND OUTPUT FOR EQUALISERS BARGAIN COMPONENTS PRICE Fig.1: the circuit consists of two separate parts, one to provide the balanced inputs (IC1) and the other to provide balanced outputs (IC2). The ± 15V rails are derived from the equaliser circuitry. signals to its non-inverting input (pin 5) it functions as a noninverting amplifier with a gain of + 2. Both input signals therefore-have a gain of 2 via IC1. To enable them to be fully floating, both input signals are AC-coupled via 33µ.F capacitors. Ideally, for best balance in the circuit, resistors Rt, R2, R3 & R4 should be as closely matched as possible. This will give the highest possible rejection of common mode signals which means best rejection of hum and noise. In practice, with t % resistors for Rt to R4, the common mode rejection will be around - 80dB which is pretty good. Now let's look at the balanced output stage which involves IC2. It could be correctly thought of as an unbalanced to balanced line driver. IC2a is relatively straightfor- ward to understand. It is connected as a non-inverting voltage follower with the negative feedback being virtually direct from the output at pin 7 to the non-inverting input at pin 6. So IC2a gives an output (at pin 3 of the XLR socket) which is in phase with the input. To get the 180° out-of-phase output, the signal from pin 7 of IC2a is fed to IC2b which functions as an inverting amplifier with a gain of unity. Its output is fed to pin 2 of the XLR socket. Both of the output lines are AC-coupled via 47µ.F capacitors. The low noise LM833 dual op amp from National Semiconductor has been specified for both !Cl and IC2. First used in the Studio 200 Stereo Control Unit published in June and July 1988, this op amp has proved itself as a very quiet unit and it is ideal in this application ITEM COMMENTS AUST. 74LSOO Nand Gate 0.60 74LS32 Or Gate 0.60 7 4LS244 Octal Driver 2.00 7 4LS3 7 3 Octal latch 1.80 4001 Nor Gate 0.50 4011 Nand Gate 0.50 4013 Dual Flipflop 0.75 4017 Decade Counter 1.20 4040 12-Stage Counter 0.95 4066 Analog Switch 0.75 4082 And Gate 0.70 1488 RS-232C Trans. 1.20 1489 RS·232C Rx. 1.20 LM555 Timer 0.65 UA324 Quad Op Amp. 0.95 LF351 =TL071 Op Amp. 1.10 LF353 =TL072 Dual 1.60 LF347 =TL074 Quad 3.35 LM1458 Dual Op Amp. 0.95 LM13600 Dual Transcon. 3.10 LM393 Dual Comparator 1.05 LF833 LIN. Op. Amp. 3.05 LM3914 Led Bar Driver 5.75 LM317T 2·30V ; 1A Adj. 1.75 LM340T5, T12, T15. Reg. 1.05 LM7905, 12, 15. Neg. Reg. 1.15 MPSA06 80V NPN Trans. 0.90 MPSA56 80V PNP Trans. 0.90 RED LEDS 0.15 GREEN LEDS 0.30 50 Mixed Diodes 2.40 4 MEG . Crystal 2.40 10 of one item & receive one free NZ customers add 12.5% GST All orders add $5.00 P&P; airmail extra. Send cheque, money order to: N.Z. 0.75 0.75 2.50 2.25 0 .65 0.65 0.95 1.50 1.20 0.95 0.95 1.50 1.50 0.85 1.20 1.40 2.00 4.20 1.20 3.95 1.35 3.85 7.20 2.20 1.30 1.45 1.15 1.15, 0.20 0.40 3.00 3.00 SAMBOR EL CTRONICS 143 BAMB0R0UGH STREET INVERCARGILL, NEW ZEALAND Phone: 021 77456 DECEMBER1989 75 INPUT -----------.BYPASS ~50k Sl One point should be noted about the balanced input stage, particularly as it applies to the stereo equaliser. Since the balanced input stage has a gain of 2, it is twice the gain of a conventional equaliser with all controls set for flat response. With a gain of 2, the maximum input signal that the equaliser can handle without overload will be reduced by 2 also. In most situations this will not cause a problem but you should be aware of it. OUTPUT ~.,. -:- (a) Fig.2a: basic block diagram for the 32-band equaliser. BALANCED INPUT AMPLIFIER BALANCED OUTPUT AMPLIFIER ..... ,--'-',--03 / BA~:Pi~ED 30---d""".d •-.;,...,.-02 BaM~8¥D 1 (b) Fig.2b: how the balanced input and output stages are added to the 32-band equaliser shown in Fig.2a. since it is capable of driving 6000 lines. Fig.2 shows how the circuits of Fig.1 are connected into the 32-band graphic equaliser referred to above. Fig.2a shows the basic block diagram of the equaliser while Fig.2b shows how the balanced inputs and outputs are added in. Essentially what happens is that the existing input and output cables are disconnected from the RCA sockets and connected to the balanced circuits instead. Fig.3 is more complex and shows how balanced inputs and outputs can be added to the the 20-band stereo equaliser. Fig.3a shows the block diagram of the stereo equaliser while Fig.3b shows how the balanced inputs and outputs are added. Building the board To enable you to add the balanced input and output stages to the mono or stereo equalisers, we have designed a two channel board. That way, you build one half of the board to suit the 32-band mono equaliser or both halves to suit the stereo equaliser. Fig.4 shows the board layout for one channel while Fig.5 shows the layout for two channels. The parts list shows firstly the parts for the mono version and then the extra parts needed to complete the stereo version. The PC board measures 87 x 75mm and is coded SC 01112891. It should be fitted with PC pins at both ends to take the input, output and power supply connections. BYPASS TAPE PLAYBACK OUTPUT LINE INPUT EQUALISED OUTPUT -;- TO TAPE .,. 00 Fig.3a: block diagram of the 20-band stereo equaliser (one channel only shown). BALANCED DUTPUT AMPLIAER TAPE ~ PLAYBACK+ BALANCED INPUT BYPASS 100k '::c" ~EQUALISED OUTPUT TO~ TAPE (b) Fig.3b: how th~ balanced input and balanced output stages are added to the 20-band stereo equaliser. 76 SILICON CHIP ~ ~~ ::-:--=--.._..• v V INPUT FROM ALISER OUTPUT BALANCE INPUT CHANNEL 1 OUTPUT TO EQUALISER INP ALANCEO LINE OUTPUT 47 t l.?8 <; II I~ :)2 I Fig.4: this diagram shows the parts layout on the PC board for the mono version. Use PC stakes to terminate the external connections and note carefully the orientation of the ICs and capacitors. 1• BALANCE INPUT CHANNEL 2 OUTPUT TO EQUALISER INP --= 1,,-L~ ~~ I INPUT FROM UALISER OUTPUT BALANCED LINE OUTPUT 5V 5V BALANCE INPUT INPUT FROM UALISER OUTPUT CHANNEL 1 OUTPUT TO EQUALISER INP BALANCED LINE OUTPUT I Fig.5: the stereo version of the project uses the same PCB pattern as the mono version. All you have to do is add two more ICs plus their associated resistors and capacitors. When assembling the board take particular care with the polarised capacitors and the ICs. All four ICs are oriented in the same direction. Once the board has been fully assembled, it should be put aside so that work can be done on the equaliser chassis. In the case of the mono 32-band equaliser, it should be fitted with one female 3-pin XLR socket (for input) and one male 3-pin XLR socket (for output). Similarly, the stereo equaliser should be fitted with two female 3-pin XLR sockets and two male 3-pin XLR sockets. These are wired to the board using shielded cable. When the XLR sockets are mount- PARTS LIST 1 PC board, code SC 01112891, 87 x 75mm 12 PC pins 4 plastic PC mounts 1 3-pin chassis female XLR socket (Jaycar Cat. PS 1030) 1 3-pin chassis male XLR socket (Jaycar Cat. PP 1020) 2 LM833 low noise dual op amps 2 4 7µF 35VW PC electrolytic capacitor 2 33µF 35VW PC electrolytic capacitor 2 1 OµF 35VW PC electrolytic capacitor 1 100k0 ¼W 4 10k0 1 % ¼W 4 1k0 1% ¼W 2 330 ¼W Extra parts for stereo version 1 3-pin chassis female XLR socket (Jaycar Cat PS 1030) 1 3-pin chassis male XLR socket (Jaycar Cat PP 1020) 2 LM833 low noise dual op amps 2 47µF 35VW PC electrolytic capacitor 2 33µF 35VW PC electrolytic capacitor 1 100k0 ¼W 4 10k0 1 % ¼W 4 1k0 1% ¼W 2 330 ¼W Miscellaneous Shielded cable, screws, nuts, washers, solder. DECEMBER1989 77 "''~ --D -~(~ MAIN BOARD POTENTIOMETER BOARD ....~ C ....~ '"""'~ \0 SK3aO '"""'~ ""~ "'B SK3bo ""~ .,,> m•~ + "'~ ~, -~:~ >c > "'"'.,, ~"' + o'\_ A ~ I +15V POWER SUPPLY BOARD ).0 TRP~~i:~~MER ~ r-r--~~\ \ \ H G F N (BLU) E A (~RN) ( / CORO CLAMP GROMMET rN ~~(GRN/YEL) ~ ~ EARTH LUG Fig.7: here's how to wire the balanced input/output stage into the 32-band graphic equaliser. The best place to mount the PCB is at the front of the chassis, immediately behind the potentiometer board. The ± 15V rails are derived from the existing power supply board. 78 SILICON CHIP C~ G ,------_,U-1-~ .. J~ ~ H - D~ ,... ~I S2 ..... K +15V ov 1c:::::::J SK6a 1c:::::::J SK5a <at>,~, LEFT ~213 ~ OUTPUT SK6b 1c::::J .{lj (i::) 2 E - 1(=:::J SK5b INPUT RIGHT MAIN BOARD OUTPUT F -~ +15V OV -15V BALANCED INPUT/OUTPUT BOARD POTENTIOMETER BOARD A ~LEO K Fig.a: for the 20-band stereo equaliser, the balanced input/output board can be mounted on the rear panel, along with the four XLR sockets (female for the inputs, male for the outputs). The PCB can be supported on pillars and secured using screws and nuts, or you can use plastic PC supports. DECEMBER 1989 79 This view shows how the two XLR sockets were mounted on the rear panel of the 32-band equaliser. Use shielded cable for the connections to these sockets. ed, the balanced board should be mounted inside the equaliser chassis using four metal pillars, screws and nuts or alternatively, using plastic clip-in PC mounts such as those made by Richco. The female XLR socket at left is used for the input connections while the male XLR socket at right provides a balanced signal output. Follow the wiring diagram of Fig.7 for the mono version and Fig.8 for the stereo version. When all your wiring is complete, check it carefully and then apply power. Check that + 15V is present at pin 8 of each IC and that - 15V is present at pin 4. Check also that pin 1 and pin 7 of each IC is close to OV (ie, within ± 10mV). That being the case, everything is apples and you are in business. · ~ Protect vour valuable issues! SILICON CHIP BINDERS These beautifully made binders will protect your copies of SILICON CHIP. In distinctive 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.1 or the 12 issues of Vol.2). It will look great on your bookshelf. * High quality * Hold up to 14 issues * 80mm internal width * Gold printed with SILICON CHIP logo on spine •;:·:} ~~~ ;~~~..... :,~ ~,,,... ..,,~ 80 SILICON CHIP . '~,;~,;!~.!·..., . "' ... Price: $All.95 plus $A3 p&p each (NZ p&p $A6). Send your order to SILICON CHIP Publications Pty Ltd, PO Box 139, Collaroy Beach, NSW 2097; or use the handy order form on page 115. BOOKSHELF Reference book on Yagi antennas Yagi Antenna Design, by Dr James L. Lawson, W2PV. Published 1986 by the American Radio Relay League, Newington, Connecticut. Hard covers, 160 x 236mm, 194 pages. ISBN O 87259 041 0. Price $35.95. This is one of the best books on Yagi design that I have ever come across. Previously, if you wanted definitive information on Yagi design which had been experimentally verified, virtually the only source were the comprehensive tests detailed in the US National Bureau of Standards' publication Technical Note 688. Much of the information in NBS 688 has been reproduced in the yearly ARRL Handbook and in more detail in the ARRL Antenna Book. Now there is a very useful extension to the NBS 688 info in the form of this book. The author wrote a series of articles on Yagi design in the US publication "Ham Radio" during the early 1980s. Now these articles have been collated and brought up to date and published in this book by the ARRL. Of particular interest is the detailed analysis of the NBS 688 results by computer. The author outlines where NBS 688 is correct and agrees with computer predictions and where the results are wrong. He even gives an analysis of how experimental errors could have occurred. It's very interesting stuff. All of the foregoing is in chapter 1. The following chapters are on simple Yagis and Yagi optimisation. There is also a chapter on loop antennas and another on the effects of ground on signal propagation from Yagis. Another very good chapter treats the topic of antenna stacking while the remaining two chapters talk on practical design of Yagis for the amateur bands. In short, a very good book and one which is a good complement to the "ARRL Antenna Book". My only lament is that the subject matter is all on amateur band antennas which are essentially narrowband designs. When will someone come out with a definitive book on antennas for TV and FM reception? That lament aside, this book can be recommended. Our copy came from Dick Smith Electronics (Cat. B-2105). (L.D.S.) AC and DC power control circuits Practical Power Control Techniques by Irving M. Gottlieb. Published 1986 by Howard W Sams & Co. Soft Covers 216 x 137mm, 248 pages. ISBN O 672 22493 3. Price $23.95. This book could be called a retrospective of power control techniques since a great deal of the material is drawn from manufacturers' data and applications literature of the last 20 years or so. That should not put you off though because at least some of the data, from RCA and General Electric, is virtually unobtainable now but is still quite useful as far as basic circuitry is concerned. Provided you remember this aspect, this book has a wealth of power control information. Chapter 1 is an overview of the subject and covers such topics as motor control with phase controlled thyristors, linear voltage regulators using discrete components and 3-terminal regulators. Chapter 2 is devoted to solid state audio amplifiers which mainly fall into two categories: (1) relatively old discrete component circuits; or (2) those based around RCA or National Semiconductor integrated amplifiers. Chapter 3 is a little more relevant as it covers the subject of regulated power supplies in detail. Both linear and switching regulators are covered and bipolar and Mosfet examples are given. Chapter 4 is devoted to speed control of electric motors and is devoted mainly to circuits using SCRs. Chapter 5 is entitled "A Variety of Useful Applications" and includes circuits for remote AC switching, a solid state relay, various lamp flashers , a 100 watt inverter and even a capacitor discharge ignition system. Overall then, this book does provide some good background information for readers looking to inform themselves on power control circuitry. However, it is certainly not a definitive book on the subject and is far from being really up to date. Our review copy came from Jaycar Electronics (Cat. BS-0528) and sells for $23.95 . (L.D.S.) DECEMBER1989 81 THE EVOLUTION OF ELECTRIC RAILWAYS The locos, rolling stock, tracks, plant and methods used by the Pilbara iron ore railways are the most advanced in Australia. The efficiencies attained with their very large "unit" trains are far above those acbieved on State-owned rail systems. By BRYAN MAHER Last episode we saw how the longest and heaviest trains in Australia, many of 31,000 tonnes, run on three privately owned iron ore railways in the Pilbara region of Western Australia. Hauling these- trains are the most powerful diesel electric locomotives in the country. In harsh, hot, dusty conditions these huge trains run great distances at speeds up to B0km/h, PT.26: THE PILBARA IRON ORE RAILWAYS (2) 82 SILICON CHIP THIS PHOTO SHOWS HAMERSLEY'S enormous wagon yard and workshop facilities at the Seven Mile Yard near the port of Dampier in the far north of Australia. The company owns 2470 ore wagons and 47 large diesel electric locomotives. Keeping all this rolling stock running reliably is a big operation in itself. sustained for hour after hour. The locomotives, rolling stock and tracks are subjected to very high loadings as the emphasis is always on maximising throughput. Given the environment, the isolation dictates that each of the three railway companies provides its own facilities, including workshops for heavy engineering repairs and maintenance. The big supercharged diesel engines are particularly heavy at around 180 tonnes, resulting in high loadings of 29.9 tonnes per axle. Mostly the locomotives are used as triple headers to pull the trains while triple bankers are often added at the rear on heavy uphill sections. These high loco weights plus the heavy wagons used require the strongest possible rails and strong sleepers with solid track foundation. Hamersley Iron presently owns and operates 47 mainline diesel electric Co-Co locomotives in the 2.7MW class. The railway headquarters are at the 46-track Seven Mile Yard, 11km east of Dampier. Here are located train holding, fuelling and storage facilities, heavy workshops. the central train controller and administration. Diesel engine loading All locos have to work very hard, whether they are pulling loaded ore trains to port or empty trains back to the mines. For the return journey from Dampier, the empty trains weigh 5400 tonnes which is a very heavy load as far as conventional railways are concerned. On the uphill drag to the mines, the locos work at full throttle for 270km of the 288km distance from Dampier to Mt. Tom Price, on grades up to 1.5%. Then with diesel engines idling, full regenerative brakes are used over the whole 98km downhill run to Paraburdoo. Loaded trains call for the diesel engines to run at full throttle for 3½ hours ascending from Paraburdoo to Mt. Tom Price. From there on to Dampier the train is on full regenerative brakes all the way except for an 18km uphill stretch at full throttle. So even when the diesel engines are idling, the traction motors are still heavily loaded because full regenerative braking means the same motor current as full traction power. When capital investment is taken into account, the most cost-effective way to use any machinery is to run on full load all the time. Except in the Pilbara, this is almost never done on other Australian railways. All trains in the eastern states give their traction motors a onehour rating at full current, with continuous rating at a lower figure, typically 92 % . However, on the Pilbara ore lines and on Hamersley trains in particular, traction motors carry full current 100% of the time for 7 or 8 hours almost without a break. On DECEMBER 1989 83 Locomotive maintenance AT THE PORT OF DAMPIER the ore wagons are unloaded in a huge rotary dumper which handles two wagons at a time, without uncoupling them from the train. This photo shows the hydraulic wagon positioner which works on rails outside the main tracks. To withstand such heavy and consistent use, these diesel electric locos require regular and thorough maintenance to their engines, traction motors, wheel sets and bearings. The workshops at Seven Mile comprise a loco running shed (trip service) and heavy maintenance and wagon repair sections. After each run locomotives are inspected, refuelled, their sand boxes filled, and then rescheduled. Usually this service is performed on three locos together as a triplehead set. Lubricants and treated coolant water are topped up and safety features checked. At fortnightly intervals air filters are cleaned and oil and water samples are tested. Lubricating oil filters are tested by measuring their hydraulic impedance by the oil pressure drop across them. Traction motor covers are removed, so that the commutators and brushes can be inspected. At 30,000km intervals, which amounts to just 40 round trips, every locomotive is thoroughly checked and adjusted. As required, components such as turbochargers, pumps or fittings are changed at the 240,000km service. Diesel engines are normally changed and overhauled at the 1,000,000km interval. At all times computer programs check measurements and data to predict any need for changes or repairs. Diesel rebuilds AERIAL VIEW OF THE ROTARY DUMPER facility at Dampier. It takes about four hours to unload a typical 30,000-tonne train. empty trains the percentage is only slightly less. The timetable shows one particular train leaving Paraburdoo mine at 4am and travelling non-stop at continuous full motor current (either full traction or full regenerative braking) until 10:30am. 84 SILICON CHIP After a 12-minute halt at a crossing loop this train then resumed full motor current until arrival at the Seven Mile Yard at 11.20am. Apart from that short crossing loop halt, the traction motors were on 100% full load current all the time. Diesel engines are completely rebuilt in the heavy engineering bays. Our photo indicates the enormous size of these V16 Alco designed engines. Alco have favoured the 4-stroke principle while the latest EMD SD50S super series have turned to 2-stroke diesels to produce more power from the same engine weight. One heavy maintenance bay has shop. floors raised to loco running board level to facilitate access to engines. The shop is provided with two 75-tonne capacity overhead travelling cranes with 15-tonne auxiliary hoists, plus bridge and column cranes. Oil, water, air etc are laid on to automatic dispensing apparatus. The six 448kW DC traction motors on each locomotive are the most critical components. Mounted down in the bogies they are the electrical components most subject to dirt and vibration. And the motors run close to the ballast and rails which in summer are at sustained high temperatures, up to 74°C. When major repairs are needed, the motors are removed, disassembled and serviced. Armature rewinding is about the only work sent to outside contractors in the cities. All other electrical repairs, including complete bogie rebuilds, are done in Hamersley's Seven Mile shops. Load testing Before and after diesel engine overhauls, the direct coupled traction alternator electrical circuit is disconnected from the traction motors and fed to a bank of fan cooled 3MW resistors as a dummy load. The diesel engine and alternator HAMERSLEY LOCOS ARE BASED ON AMERICAN designs but have been considerably upgraded to cope with the rigorous conditions in the Pilbara and the requirement for full throttle operation for up to eight hours at a time. This unit is rated at 2.9 megawatts (3900hp). are then run at full speed and the power dissipated in the resistors is measured. This is the most valid direct measurement of diesel engine power output and is a critical full load test for the alternator. Such testing is essential when the -consequences of a breakdown on the line are considered. Just imagine how expensive it would be if a 31,000 tonne train broke down on the single track line hundreds of kilometres from anywhere. Heavy wagons Now let's consider the ore wagons on Australia's longest trains. These are all eight wheelers, weighing 120-128 tonnes fully loaded, meaning each axle carries 30-32 tonnes. Many of these wagons are made by Comeng of Granville, Sydney. They are 9.34m long, 3.31m high and 3.29m wide and weigh 20.6 tonnes empty. Hamersley has 2470 of these ore wagons. To service all their ore wagons, Hamersley has a continuous main- tenance program. A trackmobile brings groups of 12 wagons into the shop where they are speedily but thoroughly serviced and lubricated, with wheelsets being changed where necessary. Up to 24 wagons are serviced each day. The brake gear is changed every 5 or 8 years. All wagons are monitored frequently in the running yard to detect any needed repairs. Wheel profiling For longest wheel and rail life and least running friction, optimum wheel profile should be maintained. Wheel tyres sometimes wear more at centre tread whereas the correct slightly tapered shape is needed for least friction on curves and true running on tangential track. Should a wheel ever drag due to sticking brakes the tyre quickly develops heat-hardened flats which make lathe turning difficult. Hamersley's Seven Mile yard includes mills and lathes for restoring wheelsets of locos and wagons to optimum profile. The lathes are situated both above ground and below droptrack pits. DECEMBER1989 85 THE PILBARA RAILWAY TRACKS are continuous ribbons of steel, from mine to the port of Dampier. The rails are laid in 400 metre lengths, before being welded. Special trains are needed to carry such long loads to where they are needed. Rotary dumping Whereas most eastern states empty their coal wagons through hopper doors in the floors, this method is unsatisfactory in the case of iron ore. Iron ore has a much higher density than coal and the extra weight would mean damaged hopper doors if the ore were dumped into this type of wagon. Therefore, the ore wagons have solid steel bottoms, sides and ends, all fully welded. Each truck must be tipped bodily to dump the load. This is done in a rotary dumper, a very large cylindrical rotating frame containing a rail track section. In operation, a fully loaded train is hauled through this cylindrical frame, moving a distance of two wagon lengths at a time. As pairs of wagons pass into the cylindrical frame, the whole cylinder - rail section, wagons and all - rotates to dump the 212 tonnes of iron ore into an underground hopper. During this process, the wagons are held on the rails within the dumper as it rotates. Since the dumper rotates on the same axis as the train drawbar couplings, there is no need to uncouple the wagons for dumping. Thus, the train is never broken. 86 SILICON CHIP The rotary dumper itself is a cylinder as big as a small house. It measures approximately 12 metres in diameter and 19 metres long, with each end having an opening the size of a railway tunnel through which the train passes. The train is fed through the dumper by a hydraulically operated car positioner which runs on a wide track parallel to the trainline. The positioner shunts back and forth as demanded by the dumper, each time pushing the train along the track by attachment at the wagon sides. The rate of unloading is 7000 tonnes per hour. On that basis, it takes about four hours to unload ·a typkal train. Heavy track The Pilbara iron ore lines are notable not only for the very high axle loading of their locomotives but also for all their rolling stock. As noted above, the axle loading for each and every ore wagon is 30-32 tonnes. This means that very heavy track is required. The iron ore lines in WA began using 59kg/m rail in the 1960s and at that time it was as heavy as anywhere in Australia. This was progressively replaced after 10 years use with 68kg/m headhardened BHP rail which is laid in 400-metre lengths. After laying, these lengths were welded to form unbroken rails 382km long. There's no clickety-clack on these railways. You might well ask how continuously welded track does not seriously distort due to expansion and contraction in the wide temperature range of the Pilbara. The answer is that it is firmly held in place by the concrete sleepers and heavy track ballasting. By 1986, all Hamersley track sleepers had been changed to concrete. Straight track sections can wear unevenly because at a constant high forward speed, wagons tend to set up a transverse oscillation. Corrective measures include rail grinding in selected places to restore the rail profile, the use of BHP head-hardened rail, and the maintenance of optimum wheel tyre cross-section. The track is aligned by laser survey and the Plasser track dynamics and geometry car which takes measurements in both horizontal and vertical directions. Accurate straight rail is important in reducing flange-rail friction on long heavy trains. Steel sleepers In contrast to the Hamersley Iron Railway, the Mt. Newman Railway has used thousands of steel sleepers, pressed from heavy plate by the BHP company. To allow for signalling track circuits, patented rail insulating pads and track fasteners hold the rails to the sleepers. Bridges Hamersley has many river and creek crossings. In fact, there are 20 steel bridges and 442 culverts. The longest river crossing is at the Fortescue River on a causeway of 30 culverts, each 3.66m in diameter. The longest steel bridge in WA is Hamersley's Spring Creek bridge between Paraburdoo and Mt. Tom Price. The span of 165m is 46m high above the (usually dry) creek bed. This 878 tonne bridge was built in 42 days. Though for most of the year there is no water at all in these creek THIS MASSIVE MACHINE WAS USED in Hamersley's extensive program to change all railway sleepers to concrete types. The machine spreads the rails, lifts out the old sleepers, installs the new concrete units and then repositions the rails, all without cutting. beds, during cyclones they are subject to ·flash flooding due to extremely heavy downpours. This means that tracks, bridges and approaches must be built to withstand cyclonic winds and the tremendous destructive forces of occasional flooding. Signals and communications A 22kV power line provides 240V supply for CTC signalling over the whole route. Also carried on the cyclone-proof power line poles are conductors for the CTC telemetry system, carrier trunk phone lines and direct telephone connections from every signal to central control. Between the power line above and the communications line below is strung an aerial earth wire which acts as a 50Hz shield. This construction is unique in Australia. The telemetry system at 28kHz and 12kHz links the 25 signal relay rooms along the track. The 200 signals are multiple aspect colour light displays for speed indication and control, with route signalling near crossing loops and yards. Track point operation is by 24V DC motors in remote areas and by 110V AC trailable point motors in the main Seven Mile yard at Dampier. central control room. Radio messages then warn the train driver. Should any equipment drag from running trains, dragging equipment detectors (DEDs) inform central controllers. Communications Communication between all trains, track maintenance and support staff is maintained using 9 UHF radio channels in the 480/481 MHz band. Trackside radio repeaters are linked by a 6. 7GHz 960 channel microwave system involving 10 microwave repeater stations over the 386km distance. Hamersley leases 60 channels of this microwave system. As well as supporting the UHF repeaters, the microwave system provides signal telemetry system backup, voice, facsimile and computer communications. ~ HBDs and DEDs Hot bearings on running trains are measured by hot box detectors (HBDs) mounted at sleeper level. Any hot wheel bearings on a passing train will automatically trigger the track-mounted temperature detector, raising an alarm in the Acknowledgements Our thanks to Hamersley Iron and Mt. Newman railways, and Comeng of Granville, NSW for data, photos, drawings and permission to publish. DECEMBER1989 87 PHONEORDER TOLL FREE ALTRONICS 008 999 007 - Don't waste your time and hard-earned cash! Do your shopping at AL TRONICS Just phone your order on 008 - 999 - 007 for the best service in Australia. Gel Cell Charger Low Cost Dual Tracking Supply (See Silicon Chip July '89) . . . . .. With memv,·y logic and OP Amps NEW Features: NEW NEW NEW NEW NEW • Adjustable output to + or - 18.5V <at>l.?A • Voltmeter • Floating ground • Dropout indicator • Load switch K 3325 Normally $99.00 Beat Triggered This month - a CRACKING $90.00 Strobe Bonus Offer r,,.. 0 0 co Cl) -z F1ashcs in time to your music, or as nonnal strobe. Exclusively customised by ALlRONICS into our H 0480 Instrument Case. Includes silkscreened panel. K 5790 Was $79.95 VALUE a: ~ <( w w a: LL Tube Option K 5795 $16.50 Now $15.00 1-------MICROEYE VECTOR The First Detector with GaAs Diodes Until now GaAs diodes have only been used in sophisticated military radar equipment. The Mic:rncyc Vector is the first consumer electronics product equipped with this new tcclmology. Why GaAs diodes make the difference • Lower threshold allows for a better signal to noise ratio • Lower sign.al conversion loss • Higher barrier reduces noise. Quite simply GaAs diodes incrc8.!JC the sensitivity of the Microeye K 1685 $23.50 The Protector Alarm Kit 0 Now $75.00 (SeeAEMJuly'8S) 0 1 ~.: We will include a set of 4 Car Alarm WARNING stickers ($3.95 value) ABSOLUTELY FREE with every Car Alarm Kit ordered this month. O> O> O> 0 0 :.~~~?.~ The intelligent way to charge Gel Cells and sealed lead acid batteries • Monitored battery voltage states charging ClJl'rcnt • Can add years to battery life • Microprocessor controlled• Ideal for radio amateurs and model racing car drivers (See SC Feb '88) This relined car burglar alarm has about every feature you could possibly want to keep would-be thieves away. Features: Internal & External Sirens Dash Lamp Flasher Battery back-up Delayed and Non-delayed inputs Easy to build and install K 4370 Was $129.00 NOW a GREATS Screecher Car Alarm (See EA Aug '86) Ear Splitting 110db Modulated Tone Now our top selling car alarm. Two sensor inputs - nonnally open and n simple connCctions to door, bonnet, boot light, switches etc. y closed, enable r----, I GREAT I K436o Great Value $39.95 ~~~!~J does not have to be anywhere near the doorway as it uses an ingenious sensor to detect the pressure change caused when the door opens. Ideal for use in office, shops, doctors surgeries, chemists etc. K 1915 Was $45.00 A special bargain this month $39.00 Vector.• Simply plugs into your cigarette lighter socket or can be direct wired into your existing car wiring • Clips onto visor • Detects mobile radar equipment. Highway/City/Modes • Separate audio alerts for X and K bands • Visor bracket• Velcro • Cigarette lighter $399 plug. Microprocessor Controlled Detector Clips on to Sunvisor Invisible from outside your vehicle - this fantastic high spec. Radar Detector detects X and K Band Radar up to an amazing 13kM. A 1530Normally$499 Up to now similar lamps sold for $t000 & more p Ias ma Lamp D·isplay Build A Sub-Woofer Adaptor (See EA May '89) Get an amazing bass Improvement for your stereo system. Fantastic, pulsating high voltage Plasma discharge continually changes shape and direction. Mode selectable to either fingertip control or sound activated, eg from voice or sound system. Provides endless fascination as it sizzles and arcs. Supplied complet• with AC Mains Adaptor A0120 Normally $199 This fantastic adaptor simply "samples" your stereo amp. outpuJ and . prqyides a single channel output lo feed a separate sub-woofer amp. Also includes an out of phase output enabling the use of a stereo amp in a bridge configuration for those who really want to rattle the floorboards. Unwanted audio spectrum is mmoved with the Frequency Control (Cutoff threshold adjustable 60- K 5560 Kit (less plugpack) $29.50 M 9020 12V AC/AC Adaptor) $16.95 130Hz) Save $50 A0980 This month only $149 be quick • Save $100 this month ,---HAVE AHAPPY---, ~~ 0 =.E;:~:~~:::~~~ I II l 'TRONICS L A I Extension: 254mm Vertlcal Extension: 254mm ' I I~L_CHRISTMAS •_-_______ ___________________________ recmnmcnd this quality Australian made product. TECHNICALINFORMATION:Illumlnatlon: 22W Fluorescent Weight: 8.16kg Lateral ~ '.· t\ 1 Normally $279.00 This LDaemspk =M~ogunn_t eied~ i/ · month 11 $229.00 Flxlng:Hcavytablebase(greyorivory)with J_t_w_o_~_= __ p1_-_n_e_x,_hl_e_=_·_ _ _ _ _ _ _ _ ,.i 5~~ PHONEORDER TOLL FREE ALTRONICS 008 999 007 SAVE $50.00 PHONEORDER TOLL FREE AL-TRONICS 008 999 007- - - -- - ~ ~ - - - - -- - - -- - - - - - - - - - - - - - - - - -- INVERTERS INVERTERS INVERTERS INVERTERS INVERTERS 300 WATT Get 240V AC Mains Power from your battery with these handy inverter kit sets POWERHOUSE Many combinations to choose from: 600W INVERTER WITH AUTO START INVERTER (See EADec'87) This inverter has the capacity to produce 600 watts of mains power which will run a fantastic array of appliances. Ideally suited to running power tCXlls, lighting (including fluros) electric motors and much more. It can be used either as a portable or a pennanent fixture. • Manual or Auto Start facilities• Low battery r,.. --- Operat,:s from 12V Car Battery 1 Auto Start draws power from your battery only when applianc.c is plugged in and "turned onw ic, battery can be left permanently co1U1Cctcd if required. • Voltage .·· _ ~ ,~"l • -:·,1 • _~ ,.,, ,. ; , ":;i';>,,, I,~ • ~ ~1.' ~ . .:-..~~:J f<J ~---- , Regulat,:d • Curnmt Regulat,:d • Current Overload unit self limits Ktir~ers ion K 6770 $425.00 : • • ~ , i, ·, ' , , 1 ' Fully built and tested • 7iOp •• • , ,. . .·,,,. ."",-,"',,. ~ !.·.' 12V Input K 6774 $525.00 : VALUE : , --. , 24V Input K 6775 $525.00 • • •. • • 0 0 40W 0) Features: 2 modes of operation, Standard Charger. Fixed or variable frequency allows frequency dependent devices. ••• INVERTER FOR SMALL APPLIANCES 100'5 OF USES AT HOME AND AWAY SeeEAAug'85 Complete Kit K 6750 $279.00 Fully built and tested K 6755 $379.00 Redford Stereo 60 Watt Patio Loud Speaker Vo lume Control For years most of w have cove~d countless miles dashing from the Patio into the lounge or family room to ''Tum it Down!" or "rrhat's notloudenooughl" etc. Now you don't lave to. Massive 100 Watt music power m S?? l...;;.;;;'";;;;;"";..fr,;;;om;;.;;l..;2V.;;ol•tcar..b;..•ttc;;,;.,;,,.Al;;.low;;,,;,•,;;,;;for;.,;,;c;isi=on=con=tr=ol=,K::::6:7::::05=$=8=9=,0=0 ======::;--:--::--:-::---::-:-:-:-:-:--:--::-~ v, CX) o O Cl) -z 0 12" Guitar/Piano Loudspeaker MassiveMagnetandSturdy Dlecast Frame $ 160.00 each or 0 a: ~ C3100 w w ...J ...J 0 a pair This imptcssivc new 12" speaker will enhance any musical instrument Amp syslcm. 97db SPL at .SM. Designed principally for guitar and piano, this "'produ= will bandlc WOW intermittently or !SOW continuous. 8 Ohm, 50mm voice call, MASSIVE 4kg magnet, 1-- Fantastic Value! Great for 2-Ways, Intercoms, P.A. 's & 100 other uses. Super Comfortable w C a: 0 w z 0 :c Q. ~ Simply fantastic as Hi-Fi ex1cnsion speakers for the Den, Games Room or Kitchen. Looks just like a down light. Excellent reproduction. Saves O.oor space. )> ~ Only $29.50 each JJ 0 . Ultra High Power Capac1ty tt•s Polypropylene Bass Drivers I~ ~ -ten C3070 Normally $129 Normally $99 Was$69.00 NOWONL Y$99 YOU SAVE$30 NOWONL Y$89 HUGE SAVINGS ON SPEAKERS \ 61 /2" WOOFER/Midrange 30Watt RMS SOW Max. C 3055 WAS $29.95 NOW ONLY $24.00 ,':) \.!!'••"<$ Our ALL NEW "Black" polyprop cone Bass Drivers exhibit qu~e astonishing low register reproduction, Power ratings quoted are conservative, Not the cheapest but definitely the BEST VALUE we know of - ANYWHERE. 12" (300mm) WOOFER 100Watt RMS 150W Max. Now $39.95 SAVE $10.00 JJ C 0980 15Watt 8 Ohm, Light grey Inner C 0981 15 Watt 8 Ohm, Dark grey Inner Huge 120 Watts RMS Massive 200 W Max. C3075 8"WOOFER 60Watt RMS 100W Max. c 3060 Was $49.95 "TI m m 10" WOOFER 60Watt RMS 100W Max. C3065 15" (375mm) WOOFER r r "DOWNSOUND" by REDFORD SAVE $10.00 The really exciting news is that all of these speakers are available at such a low discount price for this month • but be quick. stocks are limited. a NEW! NEW! NEW! NOW ONLY $29.95 Pssst... ! Listen to this! JJ A 2300 $49.95 New for '89 20Hz - 20,000Hz, 32 Ohm, I 02 db/ uW, 3 .5mm stereo jack, 6.35mm stereo jack, adaptor . Microphone Spees: Dynsmic type, 300 Ohm, l OOHz 15,000Hz, -80 db<at> !kHz, 3.5mm Mono jack. a: JJ C capacity. Five volume settings and "OFF". Includes P 8045 mounting block. Headphone Spees: < a: LJ. I Mylar Stereo THE 1 Phones I BEST 1 with Dynamic Mic,_ ___ ,. "'tJ :::c: 0 z m 0 NOWONLY $49.00 61 /2" Mid Range 30Watt RMS SOW Max. with sealed frame c 3045 Was $27 .50 NOWYOU SAVE AT $22.00 PHONEORDER TOLL FREE ALTRONICS 008 999 007 c.o c.o c.o 0 0 ~ PHONEORDER TOLL FREE ALTRONICS 008 999 007 CALLMASTER DUAL TAPE PROFESSIO NAL STEREO CONSOLE MIXER TELEPHONE ANSWERING MACHINE ••••• •••• • RF 10P • S IGNAL GENERATOR With provision for both Internal and external modulation, this generator Is a winner! : \JAlUE : ••••• • ••• A 2570 240V Mains Operated Ideal for "live" recording, our NEW Audio Mixing Console has truly sophisticated features: ...... 0 0 0) a, 0) C0 0 0 en -0z 0 a: ~ <C w w cc LL ...J ...J ~ a: w C cc 0 w z 0 :I: Q. • • • • • • • • PA mixing Fantastic tape recording Stereo/mono VCR recording R/L 5 band graphic equalisers T alkover facil~y Separate headphone level control Patch switch bank Individual controls for Microphone, Phono 1&2, Aux. line 1&2, and Master slide level This Month $399 You Save $100.00 controls. ·Blend up to two magnetic or crystal turntables, two tape decks and two microphones - all at once!! FULLY PROFESSIONAL SPECS: . Input- Mic 1: 0.5mV, 600 Ohms, Mic 2: 0.5mV, 6000hms (Low imp.), 2.5mV, 10k0hms (low Imp.); Phono Features: • Outgoing message variable from 30 to 120 sec. • Announcement-only mode • Incoming message is voice controlled • Incoming call can be monitored • Rapid erase •Hasbuilt-inmicrophane-greatfardictaticm SPECIFICATIONS: Frequency Range: 100k -lS0MHz in 6 ranges RF Output level: lOOmV RMS Accuracy+/- 3% Modulation: Internal (30% depth) - !kHz• External - 50Hz - 20Hz e Crystal locked oscillator A0512Normally$199. This month 50 only at $149 (No back orders at this price) This Month $249.00 -'-----------'--...:...--' 1&2 (Mag.) 3mV, 50k0hms; Phono 1&2 (Cry.), 150mV, 100k0hms; Tape/Tuner 1&2 150mV, 100k0hms. EquaUNr- 5 frequency bands: 60Hz, 250Hz, 1kHz, 4kHz, 12kHz. - Boost Cut Range, plus or minus 12db<at> Low PRICE GREAT SAVINGS Normally $499 1 GHz Q 1550 Normally $299.00. Save $50.00 FREQUENCY CouNTER EA Measuring Mode: Frequency Measurements CHANNEL A Range: !0Hz to 10MHz direct counter, 10MHz to 100MHz pxescaled by 10 Resolution: Direct counter: 1, 10, lOOHz switch selectable, prescaled: 10, 100, lOOOHz switch selectable Gale Time: 0.01S, 0.1S, LOS, switch selectable Accuracy: +/- 1 count+/· tinx: base error x frequency CHANNEL B Range: 100MHz to 1GHz Resolution: lOOHZ to !kHz switch selectable Gale Time: 0.0Z7S, O.Z7S, 2.7S switch selectable Protect your Home or Business from Intruders with this Period Measurements (Channel A) Range: l0Hz to 2.5MHz "State or the Art" Burglar Alarm System and save$$$ on Resolution: 10-7S, !(}-8S, J(}-9S switch selectable the cost of commercial equivalents. Totallu Measurements (Channel A) Range: l0Hz to 10MHz Resolution: +/-1 Features: • Alarm has 8 separate input circuits - 8 sectors count of input Display: 8 digits. 7mm red LED display with decimal point, gate, SUPER 8 ON SECTOR BURGLAR ~ ALARM K IT can be monitored independently • Each input circuit is provided with an indicator LED and a sectOf ON/OFF switch.• Individual sector isolation allows the user to be in some areas of the premises while others remain protected, eg Inside OFF, Ouside ON. e 1nputs accept both normally closed and normally open sensors. • Two inputs provided with an entry delay (between !(}-75 seconds). e lnl,,rnal trip warning buu.cr - alerts owner/occupant of pending alarm operation - great for the "forgetful" amongst us. This buzzer is pre-settable between S and SS seconds prior to alarm. e Unique circuit detects automatically wh:n either N/0 or N/C loops arc either open circuit or dead short, eg someone Is trying lo bridge reed switches etc.• Switched output can be used to send a silent alann through an auto-dialler circuit or similar. (See EA Jan/Feb'85 or our 1989 Catalogue for full features) ,,r overflow, kHz, MHZ and uS indication. SH oKr 1989 CatalogKe Page 62 for fwU speclfu:alions of this lop quality co11nler, now al even greater value for one month only. Q 1530 Normally $499.00 This Month Only $399.00 SAVE $100.00 Labtech Dual Trace 20MHz CRO With Component Tester Back Up Battery 12V $149.50 1.2AH S (J) 0 0 ••••••••••• WIii even clean your teeth! Won't scratch or damage - uses ordinary tap wa1cr and crc:a1cs millio~ of super-penetrating bubbles. Hospitai tests show that Ultrascnic cleaning produces bct1cr results safer than conventional nx:thods. ~ :c -0z 5065 • • • • • • • • • • • Now only $15.00 : BARGAIN : in 01nt ULTRASONIC CLEANER )> 0 Kit (Less Battery Back Up) K 1900 :c m m CX) Earns its cost ltund,rds of times over in cleaning connecton, PCB's, switcht1s,jt1w.ZUry, glass,s, watcht1s, drafting pens, etc. A. worded the Good Prodl,ct D<sign A.ward Ju. "I r-s1VE I I CETDC in 1987 Ill 11!1 ,to:-~ . -- In Just 3 minutes you will be amaud at the dlfl'erence! DESCRIPTION: This model is a dual -trace 20MHz Oscilloscope using high brightness CIIT. The vertical amplifiers have high sensitivity of SmV/Div and the frequency characteristic response with the smooth roll off exceeding 20MHz. The special circuit is designed so that a single component or components in or out of the actual circuit board can easily be tested, rcquiring no power to drive the circuit. The display shows component faults, component value, chs.racteristics a..."ld 1ests componmts dynamically. FEATURES: • Component Tes1cr • Wide bandwidth & high sensitivity • Very low power COill!WI!j>tiOn • High sensitivity X -Y mode • Z axis (intensity modulation) • Front panel electrical trace rotator • Rgual1cd power supply for greater accuracy. $100 FREE BONUS OFFER Q 0155 LABTECH DUAL TRACE CRO $899 Q 0175 2 OFF 10:1 PROBE KITS$100 usuAL TOTAL$999THIS MONTH vou PAv ONL Y $899 Typical Component Test Status Patterns A 0100 TOP VALUE NORMALLY $199.00, ONLV 1 t;~*~ THISSAVE $ 2 5.00! Labtech Test Equipment for Life PHONEORDER TOLL FREE ALTRONICS 008 999 007 (.0 (.0 (.0 0 0 ...... PHONEORDER TOLL FREE ALTRONICS 008 999 007 UHF 305MHz MICROPROCESSOR CONTROLLED Passive Infra Red Movement Detector WIRELESS SECURITY SYSTEM Why spend hundreds of dollars installing cables and knocking holes in your walls? This UHF Alarm System uses no wires and installs in an hour or so. Main Control Receiver Ideal for the loungeroom, family room or hallways. Mounts up on the wall or on top of bookshelves etc. Detects moverrent within area of 9M by 9M. s 5280 $129.00 Remote Piezo .Alarm r,.. 0 0 0, 0, 0, CX) 0 0 en -z (.) 0 Features: • Wireless reception of external or internal sensors or detectors • Selectable home or away modes. Allows internal or external arming or just external to provide protected movement Inside the building • Bulltpln plezo electric siren gives different signals for different functions • Sends signals down power llne to activate one or more remote sirens 1hc main control rcceiver runs on 2AOV AC with a 12V l .2AH battery for emergency back-up. All other units with the exception of the line carrier run on a 9V battery each. 1k average life expectancy is approx. one year. SY3tcm works around 305MHz frequency where there is less chance of a false alarm. The range of the unit is normally 80 metres in open space. Suitable for windows and doors Consists of enclosed reed switch and removable enclosed magnet. s 5270 • • • • • • • • With each system ordered we will include 3 Large • • Hand Held Control Transmitter Unit Keep it at the bedside table - allows you to arm the house perimeters when you retire or you can take it with you when you go out, arming your system after you lock the door. s 5275 $59.00 • $10.00 VALUE IN ALL • •••••••••••••••••• $349.00 ~ <C a: LL ..J s 5285 $99.00 e BANKCARD e s 5290 $125.00 $55.00 •••••••••••••••••• FREE THIS MONTH •• •• •• • • • • • (Hou,e Window) detenent stickers, 200 x 75mm • and 3 (Car Window) deterrent stickers, 70 x 25mm. S 5265 Take it with you when you move a: w w This unit is an optional line carrier receiver. Receives signal through 'AC' line i.e. it would ideally be located in, say, the roof space and plugged into mains power. Detector/Tra nsmitter Unit (Reed Switch) Front Door Keypad Control Unit This handy accessory virtually duplicates the function of the Master Controller unit but at a more convenient location. System can thus be armed or disarmed without the need to go to the Master unit. VISA e MASTERCARD e PHONE TOLL FREE 008 999 007 e NEXT DAV JETSERVICE DELIVERY Country clients please allow an additional 48-72 hours 4LTilOnlC) a: ..J ~ w Q a: 0 w z 0 c. ::c: 174 Roe St. Perth W.A. 6000 PHONE TOLL FREE 008 999 007 Perth Metro (09) 328 1599 ALL MAIL: ORDERS P.O. Box 8350 Stirling Street Exchange PERTH W.A. 6000 AL TRONICS RESELLERS Chances are there is an Altronics Reseller right near you - check this list or phone us for details of the nearest dealer. Pie•• Note: Resellers have to pay the cost of freight and insurance and therefore the prices charged by individual Dealers may vary slightly from this Catalogue - in many cases, however, Dealer prices will still represent a significant cost saving from prices charged by Altronics Competitors. Don"t forget our Expreu Mall and Phone Order Service - for the coat of a local call, Bankcard, VIM or M•tercard holders can phone order for same day despatch. MORE AL TRONICS DEALERS WANTED If you have a Retail Sh_op, you coul~ increase your income significantly by becoming an Altronics Dealer, Phone Chris Campbell (09) 328 2199 for Details. STANDARD DELIVERY & PACKING CHARGE $5.50 to 1Kg $8 over 1Kg AUSTRALIA WIDE - We process your order the day received and despatch via. Australia Post. Allow approx 9 days from day you post order to when you receive goods OVERNIGHT JETSERVICE Up to 3 Kg is $8.00- 3Kg to 5Kg is $20.00-We process your order the day received and despatch via. Overnight Jetaervlce Courier for delivery next day Country areas please allow additional 24-48 hours. HEAVY HEAVY SERVICE - All orders of 10Kgs or more must travel Express Road - Please allow 7 days for delivery. $12.00 to 10Kgs, $15.00 over 10Kgs. INSURANCE -As with virtually every other Australian supplier, we send goods at consignees risk. Should you require comprehensive insurance cover against loss or damage please add 1% to order value (minimum charge $1 ). When phone ordering please request "Insurance". TOLL FREE PHONE ORDER - Bankcard.Visa, Mastercard Holders can phone order toll free up to 6pm Eastern Standard Time. Remember with our Overnight Jetaervlce we deliver next day. WA COUNTRY BP Electronics ■ 412681 ESPERANCE Esperance Communications 713344 GERALDTON K.B.Electronics & Marine 212176 KALGOORLIE Todays Electronics ■ 212777 KARRATHA Daves Oscitronic 854836 MANDURAH Lance Rock Retravision 351246PORT HEADLAND Ivan Tomek Electronict 732531 WYALKATCHEM D & J Pease 811132 NT ALICE SPRINGS Ascom Electronics 521500 Farmer Electtonics 522388 ACT CANBERRA Bennett Commercial Electronics 805359 Scientronics 6241331 VICTORIA CITY All Electronic CO,.;,ponents 6623506. SUBURBAN CHELTENHAM Talking Electronics 5842386 CROYDEN Truscott Electronics ■ 7233860 PRESTON Preston Electronics 4840191 COUNTRY BENDIGO KC Johnson ■ 411411 MORWELL Morwell Electronics 346133 QUEENSLAND CITY Oelsound P/L 8396155 SUBURBAN CAPALABAKingsway Electronics 3902399 WOODRIDGE David Hall Electronics8082777 COUNTRY CAIRNS Electronic World ■ 518555 BUNDABERG Bob Elkins Electronics 721785 GLADSTONE Supertronics 724459 MACKAY Philtronics ■ 578855 ROCKHAMPTONAccess Electronics (East St.) 221058Xanthos Electronics 278952 TOOWOOMBA Hunts Electronics ■ 329677 TOWNSVILLE Solex ■ 7724466 SA CITY Force Electronic ■ 2125505 SUBURBAN BRIGHTON Force Electronics ■ 3770512 CHRISTIES BEACH Force Electronics ■ 3823366 ENFIELD Force 6Iectronics ■ 3496340 FINDON Force Electronics ■ 3471188 LONSDALE Force Electronics ■ 3260901 COUNTRY MT.GAMBIER South East Electronics 250034 WHYALLA Eyre Electronics ■ 454764 TASMANIA HOBART George Harvey ■ 342233 LAUNCESTON George Harvey ■ 316533 Nichols Radio TV 316171 NSW CITY David Reid Electronics ■ 2671385 CARINGHAH Hicom Unitronics 5247878 COUNTRY COFFS HARBOUR Coifs Habour Electronics 525684GOSFORD Tomorrows Electronics 247246 GRAFTON East Coast Electronic 431250 NELSON BAY Nelson Bay Electronics 813685 NEWCASTLE Novocastrian Elect.Supplies ■ 621358 NOWRA Ewing Electronics ■ 218412 RAYMOND TERRACE Alback Electronics 873419 WINDSOR M & E Electronics 775935 WOLLONGONG Newtek Electronics ■ 271620 Vimcom Electronics 284400 PHONEORDER TOLL FREE ALTRONICS 008 999 007 "'C :c 0 z m 0 JJ C m JJ a rr- ,, JJ m m )> !:i JJ 0 -z C') CJ) 0 0 (X) (0 t.O (0 0 0 ~ AMATEUR RADIO By GARRY CRATT, VK2YBX Build this simple HF receiver & tune into the 40-metre band This little receiver uses just two ICs and can tune the 40-metre band from 7MHz to about 9.4MHz. It can be built in an hour or so and when used with a suitable antenna, is capable of resolving AM, CW or SSB signals. This single chip design uses a minimum of components to provide quite useful results on any HF band. It is based on a circuit that was originally published in the ARRL magazine "QST" in September 1986, but our version includes several modifications. The basic concept of this new unit is similar to the Narrow Band FM Receiver described in the March 1989 issue. That unit was based on Motorola's MC3362 FM receiver chip. By contrast, this new design uses Motorola's MC3359 which is a low power narrow band FM IF strip. The MC3359 is used in virtually every VHF or UHF amateur transceiver made today. Fig.1 is a block diagram of the chip while Fig.7 shows the internal circuitry. As can be seen from these two diagrams, the MC3359 contains a crystal oscillator, a double balanced mixer, a 6-stage 455kHz limiter, a quadrature detector, an audio amplifier, and muting and scan control circuits. How it works Although the MC3359 is designed as an FM IF strip, it is possible to access a sufficient part of the internal circuitry to trick the chip into receiving AM, CW, and SSB signals. There are two points at which we can apply amateur ingenuity to accomplish this task, as discovered by Bruce Williams, WA61VC, Assistant Technical Editor of "QST" magazine. He found that the crystal oscillator, accessible at pins 1 and 2, could be used as a Colpitts (LC) oscillator. It could thus form quite a good VFO, there by enabling the receiver to be made tunable. ANTENNA AUDIO AMPLIFIER t------1i5 SCAN CONTROL - - - - f i 4 SQUELCH INPUT QUADRATURE 8 INPUT Fig.2: although the MC3359 is an FM IF strip, it can be "tricked" into receiving AM, CW & SSB signals. This diagram shows the configuration of the simple receiver described here. ◄ Fig.1 (left): block diagram of the MC3359 narrow band FM IF strip. It contains an oscillator, a double balanced mixer, a 6-stage limiter, a quadrature detector, an audio amplifier, and muting and scan control circuits. 92 SILICON CHIP I Our prototype receiver uses two ICs and tunes the 40-metre band from 7-9.4MHz. The receiver should be installed in a metal case and the tuning gang rigidly mounted to prevent tuning drift. Power comes from a 9V DC souce. performance can be optimised for CW, SSB or AM reception. For SSB reception, a CFU455H filter having a 6dB bandwidth of ± 3kHz is the best choice. Narrower filters will be more suitable for CW reception, while wider filters improve the AM reception. Fig.3 shows the various filter specifications. Having passed through the 455kHz filter, the signal is then fed Fig.2 shows how the MC3359 can be configured to form a simple amateur receiver. The incoming RF signal is connected to the input of the double balanced mixer where it is mixed with the VFO signal. The output of the mixer is at 455kHz and is fed via a 455kHz ceramic filter to the IF amplifier at pin 5. By selecting a 455kHz filter with suitable bandwidth, the receiver ■ Resin Molded Type 455KHz ---------■ Part Number General S e r ie s - - - - - - - - CFU455 D CFW455 [l e _~,,~ 't j: li u .t ,.. : ---r:; '~~ 4 2 1 Q_on nect1on 3 (f " Inp ut 12 . Ground 13' : Oulput CF V455 '.] .l I~ I I 2.9 2.9 2.0 - , ..; I o 5-; 1. 0 :~ 2.0 Connection ,1 . Input 2 3 ,4 · Ground ,5: Output 1.32.82.82.l lff+p;; S I ConneC\IOn ·1 · input ,2 J J · Grou nd (S · Output CFU CFW CFW455B CFU455B2 CFW455C CFU455C2 CFU455O2 CFW455O CFU455E2 CFW455E CFU455F2 CFW455F CFU455G2 CFW455G CFW455H CFU455H2 CFW4551 CFU45512 CFU455HT CFW455HT CFU4551T CFW4551T CFV455E CFV455E1O to the quadrature detector. While this is suitable for FM reception, it would appear at first glance to be quite unsuitable for AM or SSB reception. However, the internal configuration of this quadrature detector is similar to that of a double balanced mixer and can also be used as an AM detector! If a 455kHz BFO (beat frequency oscillator) signal is introduced to Stop Band Att. Att. 6dB (dB)min. Band Width Band Width (KHz ) min . (KHz ) max. CFU CFW 27 35 ±15 ±30 27 ±12.5 ±24 35 27 35 ±1 0 ±20 +15 + 7.5 27 35 :27 + 6 +12.5 35 + 4.5 25 35 ±10 25 35 ± 3 ± 9 25 ± 7 .5 35 ± 2 60 35 ± 3 ± 9 35 60 ± 7. 5 ± 2 +16 + 8 50 + 7.0 +12.5 50 Insertion Loss (dB) max . ln ./Output Impedance (KQ ) 4 4 4 6 1.5 1.5 1.5 1.5 2 2 2 2 6 6 6 6 2 1.5 1.5 6 6 6 6 2 • Stop band a11enuat1on ,s specified w, thm 455± lOOKH i • A 11enuat1on band width 1s spec1f1ed by 1he wid th of CF U : 40d8 . CFW : SOd B and CF V : 60d B. Fig.3: this table from the IRH catalog shows the characteristics of various ceramic filters and their pin configuration. Narrow filters are best for CW reception while wider filters are best for AM reception (see text). DECEMBER1989 93 68(! r------~----.....----<1---+-------WtA....-+9V ANTENNA 220 + 16VWr 22pF 18 180pF 17 120pF II L1:: II 16T VC2 8-1D0pF 150pF VCl 3-1DpF 1C1 390pFI +6V MC3359 .,. 10D(l S1 10 220 + 16VWJ 10 16VW + - 220 .,. II L3 II 1mHII .,. .,. G0o VIEWED FROM BELOW L1 : 16T, 268&S ENCU ON T37-6 FERRITE RING L2 : PRI 13T, SEC 3T, 268&S ENCU ON TS0-6 FERRITE RING SIMPLE 40-METRE RECEIVER Fig.4: the final circuit for the simple 40-metre receiver. Tuning capacitor VC2 is used to tune the VFO so that it is 455kHz higher than the wanted signal. The 455kHz signal from the mixer is filtered by FU and then fed via the IF amplifier to the detector. The output signal appears at pin 10 and is amplified by IC2. pin 8, the circuit thinks it is a product detector and is able to resolve SSB signals. Because the BFO has some tuning adjustment, the actual BFO frequency can be located close to one side of the IF passband thereby eliminating the beat signal on the other side of the passband. This means that if the receiver is built for 40-metre reception, the BFO should be tuned to allow reception of the 1SB signal (according to convention). If the receiver is built to receive higher frequencies, the BFO can be tuned for USB reception. Final circuit Fig.4 is the final circuit of our 40-metre band prototype. It shows the incoming signal fed from the antenna via a matching network to pin 18 of the MC3359. This is the input to the mixer. Tuning capacitor VC2 is used to tune the VFO so that it is 455kHz higher than the wanted signal. 94 SILICON CHIP The 455kHz output from the mixer appears at pin 3 and is fed via the 455kHz ceramic filter to the IF amplifier and then to the detector. There is insufficient audio at pin 10 of the chip to be of much use, so a simple audio amplifier using an 1M386 was used to increase the level to drive a small speaker. This produces adequate volume levels for normal listening conditions. S1 switches in the BFO for reception of SSB & CW signals. This switch applies DC volts to an MPF102 N-channel FET, which is configured as a Colpitts oscillator. The frequency determining element of the BFO is a 455kHz IF transformer (Tl) from a DSE coil pack (white). This transformer also couples the 455kHz signal from the BFO to pin 8 of the chip. The entire receiver draws less than 15mA and can be operated from a 9V battery. Zener diode ZDl ensures that the supply voltage is held at 6.2V. Construction All the parts with the exception of the tuning capacitor are mounted on a small PC board. This is coded SC06111891 and measures 121 x 53mm. Fig.5 shows the parts layout on the board. The order of assembly is not critical but be sure to keep component lead lengths to an absolute minimum. Pay particular attention when installing the ICs, zener diode and electrolytic capacitors. These are all polarised components and must be installed exactly as shown. Coil 13 is a commercial lmH choke (available from Dick Smith Electronics or Altronics) but you will have to wind 11 and 12 yourself. 11 consists of 16 turns of 26 B&S enamelled copper wire (ECW) evenly spaced on a T37-6 ferrite core. Clean and tin the ends of the winding before soldering the coil to the PCB. l ANTENNA VC2 -- 120pf ~ '" ~~ =!i + . 220pf 220µF,/ 001~ . . 0. 68k . A L30 ~ Hr . 01' 2 ,~ '" • • O 2~ - 0 VC3 ·+;.____:.=.__ ¥ ~ ""' 1 PCB, code SC06111891 , 121 x 53mm 1 TS0-6 Amidon ferrite ring or equivalent (ID 7mm, OD 13mm) 1 T37-6 Amidon ferrite ring or equivalent (ID 5mm, OD 10mm) 1 SPOT miniature toggle switch 1 miniature 8-ohm loudspeaker 1 1 OkO log potentiometer 1 CFU455H ceramic filter (see text) ,m~=:. . e 22pf e.()e180pf ~ ~~10uf PARTS LIST I + __:...:___ ___, ,r. 1- 0470 G:\ ill!} ~-·\; \\ 80 SPEAKER Semiconductors 1 MC3359 narrowband FM IF strip (IC1) 1 LM386 audio amplifier (IC2) 1 MPF102 N-channel FET (01) 1 6 .2V 400mW zener diode (ZD1) Fig.5: install the parts on the PCB as shown here, taking care to ensure that all leads are as short as possible. Use polystyrene capacitors where specified as these offer better stability. , Fig.6: this is the actual size artwork for the PC board. 12 has two windings of 26 B&S ECW on a T50-6 ferrite core. The primary winding consists of 13 turns while the secondary (on the antenna) side consists of three turns wound adjacent to one end of the primary. Note that one end of the secondary winding is kept free for connection to the an.tenna. The tuning gang and the board should be mounted in a metal case, with the tuning gang bolted in position. A stout length of tinned copper wire is used to make the connection to the fixed plates on the gang (note: make the connection to the largest section). Don't use a flexible lead for this connection if you do, the capacitance will vary as the lead is moved and this will detune the receiver. The tuning gang must be rigidly mounted for the same reason. Keep the connection between the gang and the PCB as short as possible (we simply lashed up the prototype to verify the circuit concept). Ceramic filters The parts list specifies a CFU 455H ceramic filter which has a 6dB bandwidth of ± 3kHz. This is ideal for resolving SSB but can also be used for CW. Alternatively, you could use a CFU4551/CFW455I ( ± 2kHz) for CW work only, or a CFU455E/CFW455E ( ± 7.5kHz) for AM reception. Other ceramic filters would also be suitable. If you use a 5-pin type, it can be glued to the copper side of the PCB and its leads connected to the pads using tinned copper wire. Alignment Alignment of the receiver is quite simple. First, the VFO must be ad- Inductors L 1 - 16T 268&8 ECW evenly spaced on Amidon T37-6 ferrite ring L2 - Primary 13T 268&8 ECW on Amidon TS0-6 ferrite ring; secondary 3T 268&8 ECW at one end of primary L3 - 1mH choke (DSE Cat. L 1820; Altronics Cat. L7046) T1 - 455kHz coil (white from DSE L-2060 coil pack) Capacitors 2 220µF 16VW PC electrolytic 1 1 OµF 16VW PC electrolytic 2 0.1 µF ceramic 1 .04 7 µF metallised polyester 2 .001 µF ceramic 1 390pF polystyrene 2 220pF polystyrene 1 1 80pF polystyrene 2 120pF polystyrene 2 1 OOpF polystyrene 1 33pF ceramic 1 22pF ceramic 1 3-1 OOpF tuning capacitor 2 3-11 pF trimmer capacitors (white - Altronics Cat. R-4003) Resistors (0.25W, 5%) 1 1OOkO 1 1 000 1 68k0 1 470 1 5600 1 100 justed so that it operates at 455kHz above that part of the HF band required. Its frequency can be checkDECEMBER 1989 95 r----------------------------------, ---------, ----------, I ., I II I·, 14 4 I I 77 I I I 18 11 16 I I I 10 ---+---e I I 33 k 33 k 33 k 3.5 k 7k 50 k 50 k 750 II 2.5 le I OSCILLATOR - I M IXER I OP AMP 8 ROADCAST DETECTOR I I I I I -------------------------------------------~-----------,I LI MITING IF AM PLIFIER DETECTOR ANO AFC I I I I I I I I I II s n-~---1----1 ~+----1-~~+====i:~~=t=====!====::t=:;;;;;;;:::::ii-J o1 33k 33k 10 33k k 33 k 0-4>-----+-..___..,___ _+-_ __.__ _......__......;......_.,___ 11 I 5k ......_.,__....._.~.,____........_J ___._ _ I s L---------------------------------~---------------------~ Fig.7: inside the MC3359. It contains an oscillator, a mixer, limiting circuitry, and a quadrature detector. ed by using a CRO (or sensitive frequency meter) to monitor pin 2 of !Cl. There will about 80mV p-p of signal here. Adjust trimmer VC1 so that when the tuning gang (VC2) is fully in mesh, the lower limit of the desired band plus 455kHz is displayed. For example, if you want the lower limit to be 7.0MHz, adjust VC1 so -that the frequency meter reads 7.455 MHz. This should now mean that with VC2 fully out of mesh, pin 2 will be at the upper frequency limit plus 455kHz. If you don't have a CRO or a frequency meter, a HF receiver and a suitable sniffer probe could possibly be used instead. The prototype covered the entire 40-metre band from 7.0MHz and extended up to about 9.4MHz, thus allowing reception of some shortwave stations. The BFO can now be adjusted. Its output frequency is best monitored Where to buy the parts The MC3359 is available from VSI Electronics in Sydney. Phone (02) 439 8622 (offices in all states). Murata ceramic filters are distributed by IRH Components (phone 02 648 5455). You can also try Dauner Electronics, DSE and Stewart Electronics. The L1 & L2 toroids are available 96 SILICON CHIP from Amidon stockists. Try R.J. & U.S. Imports, PO Box 157, Mortdale, NSW 2223; or Geoff Wood Electronics; or Truscott Electronics. The 3-1 OOpF tuning gang can . be obtained from Dauner Electronics. The Jaycar Cat. RV-5740 (0-160pF) and RV-5736 (0-1 00pF) types could also be used. at Ql 's source. Adjust Tl so that the output frequency of the BFO is close to one edge of the IF passband (ie, slightly less or slightly greater than 455kHz, depending on whether you wish to receive the LSB signal or the USB signal). Finally, trimmer capacitor VC3 in the antenna circuit should be adjusted for best reception. Antenna For best results, the receiver should be used with a long wire antenna, installed as high as possible. The prototype was able to receive many stations on 40 metres operating CW and SSB, as well as commercial AM shortwave transmissions. References (1). "The SIMPLEceiver", by Bruce 0. Williams, W A6IVC, "QST" magazine, September 1986. (2). Motorola Linear & Interface !Cs, 2nd edition, 1987. ~ This year we gave away 2000 copies of our 1989 ACEL Electronics Yearbook, the definitive guide to Australia's e lectronics components and equipment so urces . And you told us it was the most up-to-date and comprehensive refe rence tool of its kind. Well the 1990 e ditio n is even better - more companies, more brand names, more overseas sources, more fax numbers , more product categories; it's 100 pages bigger and better. This time, it's not free . The 1990 edition of ACEL Electronics Yearbook costs 575 - it w ill save many times this in phone calls and time. • quicker so urcing • more alternative suppliers • fewer wasted pho ne calls • precious time saved ACEL Electronics Yearbook has uniqu e features like • a logo identification section and • a section detailing the catalogues available from each su pplier. •••••• El ■11111 ■11111 111111 111111 ACEL . Yearbook ectro111cs • comprehensive product listing • extensive brand names indexing • local sources fo r overseas companies • co mplete address and fax details Simple to use - a n d simple to obtain . Fill in the coup on and p ost it to us. -- -------------- - ------ - ------- - ----------- - --- --- - ---- - ----~ -- - ------- - -- Return to: ACEL Information, PO Box 1040, North Sydney, NSW 2059. ACEL Electronics Yearbook 1990 Please send .... .. .. ..... copies at S75 each (incl. de live ry) I enclose my cheque fo r S .... .. ...... .... .. .. .. or Please charge me - my orde r Numbe r is ....... .. .... .. .......... .... .. .. . Name: .. ...... .... .... ...... . .. . ....... .. .. ....... . .. .. .. . .. .. ..... .. ... . .... . ... ... Position: ...... .. .. .... ... .. .. ..... ...... .... ...... ... .... .. .... ..... . . Company Name: .... .. ... .... .. .. .. .. .. ... .... .. .. .... .. ... .... ........ .. ...... .... ... .. ...... .... ....... ...... ... .. .... .. ... .. .. ....... .. ... ... .... ..... ... .. . Address: ... .... .. ... ..... ..... .... ....... ............ .......... ...... ..... ... ... .... ... ...... ...... .. ........ .... ......... ......... ..... .... ........ .. ........ ....... Phone : ..... .. .... ... ... .. ... ..... ... ......... .... ... Signature: ....... ... ..... .... ....... .. ......... ... ............... .. .... .. ... .... .. ..... ........ ... ... . Sydney 98 Arthur Street North Sydney 2060 Phone: (02) 922 6088 Fax: (02) 929 7214 Telex 74964 Melbourne 71 Queens Road Melbourne 3004 Phone: (03) 529 5200 Fax: (03) 529 4680 Telex: 35364 Brisbane 178 Cane Street Redland Bay 4165 Phone: (07) 206 8031 Fax: (07) 206 8031 ACEL Information THE WAY I SEE IT By NEVILLE WILLIAMS Broadcast television: an industry that's not sure where it's going! Looking hack over the past year, broadcast television stands out as one industry that's even more confused now than it was 12 months ago. Aggregation and redeployment to UHF isn't working out, satellite broadcasting is facing major problems, HDTV is nowhere and to cap it all, our major commercial networks appear to be strapped for cash. For this December issue, I had planned to pursue the theme "89 The Year That Was", revisiting subjects that had been raised during the past 12 months and picking up letters and comments that had been squeezed out by pressure on space. But before I'd put finger to keyboard, events in the business world had exposed the serious financial position of Australia's commercial television networks, shifting the emphasis from expansion and gee-whiz technology to survival. ' No less to the point, inquiries about the progress of aggregation and the new UHF services in southern NSW indicated that the technical situation was in the very kind of mess that has been foreshadowed in these columns over the past 18 months - in the May, October and December 1988 issues, and again in April this year. UHF and aggregation Pursuing its long-term policy of clearing the 88-108MHz band for FM broadcasting (SILICON CHIP, May 1988), the Federal Government found itself on a course which 98 SILICON CHIP culminated, three or four years back, in their so-called "aggregation" plan. It went well beyond the original intention to redeploy services on channels 0, 3, 4, 5 and 5A to the UHF TV bands (526-582, 603-820 MHz). Now other regional VHF stations would also be transferred to UHF to make extra channels available - sufficient to accommodate the same number of services as already available in the major capitals: ABC, SBS and three commercial broadcasters. To prevent the major networks from simply absorbing the regional outlets, the Government legislated to limit their direct coverage to 60% of the total population. This left the way open for independent broadcasters to form secondary networks (aggregation) financially independent but free to affiliate with a major network for the supply of programs. Four major areas are involved at present: southern NSW, northern NSW, regional Queensland and regional Victoria, each with about one million potential viewers. Because of its proximity to Sydney and the fact that it includes channel 4 (94-l0lMHz), the Illawarra area became the first to undergo re-organisation, with the remainder of southern NSW close behind. The resulting secondary networks Prime, WIN and Capital - are affiliated respectively with networks 7, 9 and 10. From the outset, there was doubt about the limited reach and penetration of UHF transmissions, compared with those on the existing VHF band. Would UHF/aggregation work out in practice? The Department of Transport & Communications (DOTC) seemed to take the view that equivalent UHF coverage could be ensured by a combination of more powerful base transmitters plus (a few) translators for shadowed areas. But while some viewers are delighted with the extra channe_ls, overall coverage of the new highpowered UHF transmitters is poor compared with their less pretentious VHF counterparts . The signals just don't penetrate many areas and are subject to serious fading in others. As I write, they're still arguing about where to locate a key translator for the Milton/Ulladulla area and those already operating are the subject of frequent complaint. One low-power installation is reportedly so ineffective that a viewer who can see the mast from his back porch can't receive the signal! According to Jim Yalden, an experienced serviceman and my main contact in the Illawarra region, antenna suppliers will no longer accept responsibility in areas plagued by signal fading. They'll do their best but only after warning that a signal that's here today may be gone tomorrow. Without this precaution, they'd be plagued by call-backs. Kangaroo Valley, a land-locked area behind the coastal range, is hopeless for UHF. You get a signal of sorts, says Jim, but invariably one with a maze of ghosts from the surrounding escarpments. Not only that but the signal pattern is unstable, presumably because of changing atmospheric conditions. Despite all this, we have yet to hear that "almighty hell of a scream" predicted for the day they switch off the channel 4 and 5A VHF transmitters. The reason is simply that the authorities haven't so far got around to it! Aggregation or aggravation? VHF transmissions were supposed to disappear at the start of the year; then, as rumour would have it, in March, April, June and October. The latest tip, as I write, is January 1990. Even the people at WIN-4 don't know! In the meantime, DOTC and the responsible minister are caught between the proverbial rock and a hard place. He/they are loath to terminate the VHF transmissions until the UHF service is in place. On the other hand, they are under pressure to get rid of WIN-4 in particular so that the re-allocation by tender of a couple of Sydney AM broadcast stations to FM can be implemented. More cautious approach Indications are that DOTC has Rlready backed away from aggregation based on all-UHF technology. According to on-the-spot 11lawarra watchers, Bateman's Bay, Bega and Eden will now be served by the existing commercial VHF translator and two new UHF translators for the additional channels. Other major areas centred on Canberra, Orange and Dubbo will retain a VHF service for the ABC and the existing commercial station, with the new commercial outlets and SBS allocated to UHF. Mixed aggregation will permit a more flexibile timetable for the incoming broadcasters but it may also place them at a serious initial disadvantage. It could even prejudice the ultimate viability of the five-channel concept. An overriding consideration is the fact that rural commercial TV has always been financially precarious. Some stations have done well and could arguably remain profitable with one competitive station. Others get by, while still others have survived only by local mergers; a few available licences have never even been taken up. In his "Canberra Insider" column (Sydney Morning Herald, Sept. 2, 1989), Tom Burton says: "In their greed to get themselves three commercial signals across the country, the networks forced the Government into a scheme that was never economically viable. There just were never enough TV sets in regional Australia to underwrite three commercial free-to-air services". Right or wrong? It looks like we're going to find out the hard way! Satellite TV broadcasts As for AUSSAT, its role in nationwide TV broadcasting is very much in question. It carries programs from the ABC and SBS, and that's fine, as far as it goes. There's no way, however, that the major commercial networks will want to use it for everyday TV broadcasting, now that they have nationwide access. That leaves the existing Remote Commercial Television Services (RCTS) operators, each with a potential and very scattered audience of around 100,000 viewers. According to a report in the SMH Guide (Sept. 11, 1989), all three are in a parlous state because, they say, there is no way that AUSSAT's present charge of around $4 million per annum for a 30W transponder can be recouped by a free-access service from the available audience. Right now, the future of the Remote Commercial Television Services is in the melting pot. The Federal Government may decide to subsidise the cost of transponder POLYSTYRENE CAPACITORS Made here in Australia? Made Special to Type? Polystryrene Capacitors - 1 0pF to 1mF Voltage Range 63VDCW to 10,000 VDCW Tolerance - 0.25% to 10% Allied Capacitors Australia manufactures capacitors to the specification of the customers using high quality, imported polystyrene and aluminium foil with a tolerance of 1 micron. Our capacitors are manufactured to the system of Total Quality Control. We can provide Just In Time delivery if required, together with a Certificate of Conformance if requested. Specific values between 10pF and : 1uF are no more expensive than standard value components . You can now design circuits to use a single capacitor rather than a number in parallel or series to achieve a desired value . Personalised labelling is available at no extra cost. Your component code or name can be built into the capacitor. Minimum runs of only 25 allow you to specify a particular value for a prototype run. Delivery lead time for short runs is 3 to 4 working days, and for longer runs is less than 2 weeks . We are also able to produce capacitor styles for applications such as dual mount, end filled and mini style capacitors. INTERESTED? Call us now on: (02) 938 4690 ALLIED CAPACITORS AUSTRALIA PO Box 740 Brookvale, NSW 2100 DECEMBER 1989 99 THEWAYI SEE IT - CTD hire. Conversely, it may decide not to, which would probably mean the end of RCTS. AUSSAT and Pay-TV In the meantime, AUSSAT faces problems with its own capital intensive operation. Its second generation Hughes satellites are contracted for launch in late 1991 by Chinese Long March rockets but in the present political situation, there is no guarantee that the American satellites will make it to China in the first place. If they have to be launched by American or European contractors, there will be a huge increase in launch costs. Which brings me to both a coincidence and an irony. On the very morning after I wrote the above, an article in the daily press (SMH, Sept. 21) suggested that Pay TV may be in sight for Australia. It had been stalled by a 4-year moratorium that was due to end in September next. Scientific Atlanta, a company already involved in current AUSSAT services, is keen to supply from 5 to 7 channels of pay TV, with multi-lingual subtitles, automated billing, parent control facilities, a "fingerprint" anti-pirating system, etc - facilities already available with AUSSA T's B-MAC system. By 1992 the second generation satellites should be in place. Considering that the Federal and State Governments, AUSSAT and some of the present satellite services are strapped for cash, there seems little doubt what the Federal Government's decision will be when it con- siders the fate of Pay TV in a few week's time. High definition TV The subject of high definition television (HDTV) was first raised in the April 1989 issue by W.G. of Wentworthville, NSW, who was clearly impatient to see high definition, wide-screen, 3-D television introduced while he was still around to enjoy it. While admitting to a natural interest in the relevant technology, I suggested that viewers generally did not appear to share his impatience. We had not exhausted the potential of current standards, 3-D technology was still too clumsy, HDTV would be adopted when the time was ripe, etc. W.G's ideas were subsequently challenged in a long letter from another reader, K.W., discussed in the August and September issues. While agreeing with my own summation, K.W. was keen to emphasise the problems that would need to be addressed in the area of video production if the source material was to be equal to the demands of HDTV. There the matter might have rested had not the subject surfaced quite independently in the IREE, with references in recent issues of "IREE Monitor" and a symposium at the Melbourne IRECON in September. HDTV also received recent mention in the TV show "Beyond 2000". In a 10-minute segment, the commentator indicated that the Japanese, notably NHK and Sony, were .,•••, ;•.r..1;;.:.11: RCS Radio Pty Ltd is the only company which manufactures and sells every PCB E, front panel published in SILICON CHIP, ETI and EA. 651 Forest Road, Bexley, NSW 2207. Phone (02) 587 3491. 100 SILICON CHIP trying to create a demand for HDTV, as of now. Their aim was to establish a new market for the domestic electronics industry, as well as Japanese leadership in "third generation" TV. The introduction of HDTV would fairly obviously provide an opportunity to establish a new, worldwide transmission standard. If Japan could set up an industry based on a standard of its own choosing, other nations would be under pressure to conform. But HDTV faced major political as well as financial and technical problems. American and European interests were both determined to grab a slice of the HDTV "cake" but they were taking a much longer view - as it turns out, into the next century. Japan is impatient too That the Japanese were intent on creating immediate local demand was evident from the ''Beyond 2000" coverage of the daily 1-hour HDTV broadcasts in Tokyo. The emphasis seemed not to be on panoramic detail and colour, which is what HDTV is all about. It was on what a Japanese audience most likes to watch - Sumo wrestling - which scarcely needs more graphic portrayal! Currently, Japan is backing NHK's 1125-line 60-field system, the US 1050/60 and a European consortium 1250/50 - the last two by doubling the present line structure. In an effort to rationalise the position, Australia proposed the socalled "Common Image Format" in October 1988 - an approach that has since won growing support. Adapting the image film concept, it envisages an electronic image with an aspect ratio of 16:9, made up of 1080 active lines with 1920 active pixels per scan line, thereby providing for equal vertical and horizontal resolution. The proposed Japanese and European standards should both be able to accommodate that number of active lines. That should be enough on the subject of broadcast television. Now what else did I want to talk about? Curses, I've run out of space again! ~ JAYCAR DISCONTINUED PRODUCT SELLOUTLimited stock. No backorders. All specials may not be available in all stores. For more information on products see our catalogue. Cat No. Description AA2096 Car Aerial Ext lead 3.Smt AM4060 DM905 AKG Bal Uni AM4062 DM902 Bal Mic 600ollm AM4065 DM9040 Bal Dual Imp AM4115 Gooseneck 15cm AM4119 Microphone Desk Stand AM4122 Microphone Roor Stand HG9912 Bishop Graph 24 OIL Pat HG9913 Bishop Graph 28 Oil Pat HG9914 Bishop Graph 40 OIL Pat HG9928 Bishop Graph Univ Target HG9936 Bishop Graph Tape .093" HG9952 Bishop Graph Edge Conn KA1220 Signal Tracer Kit KA1681 Short Wave Radio • 3 Band KA1694 Volt/Continuity Tester KA 1700 Power Transistor Tester KM3064 Octave ED Module KE4731 Telephone Intercom KC5024 Modern End Filn Ind KC5027 Ph Meter Kit KC5044 Car Safety Lights KC5049 Aux Brake light Flash H3180 UHF TV Ant 10 Element LT3194 TV Gutter &kl+ 300A lead LA5095 Car lgn Ktt/Dash light MF1033 PL15/20VA Ferg T/Former MF1042 PL30/20VA Ferg T/Former MF1045 Pl40/20VA Ferg T/Former MF1072 Pl15/60VA Ferg T/Former MF1075 Pl18/60VA Ferg T/Former MF1078 PL24/60VA Ferg T/Former MF1081 Pl30/60VA Ferg T/Former MF1082 Pl40/60VA Ferg T/Former MT2119 Toroidal 45 + 45V 160VA MS4002 Mains Filter 240V 3A fll.4104 Lettering• Silver 7mm fll.4106 lettering - Yellow Auro OM1573 Digital Tune Up Tester OT2325 Colour Bar Pattern Gen Was $8.95 $t29.50 $77.50 $115 $5.50 $7.95 $65.00 $6.50 $6.50 $6.50 $6.50 $4.95 $6.50 $27.95 $79.50 $29.95 $22.95 , $59.95 $49.95 $8.95 $49.95 $29.95 $17.95 $59.50 $12.50 $39.95 $34.95 $34.95 $34.95 $45.00 $55.00 $55.00 $55.00 $55.00 $65.00 $26.50 $2.39 $2.39 $109.50 $249 Now $4.95 $79 $49.95 $75.00 $3.95 $4.95 $39.95 $3.95 $3.95 $3.95 $3.95 $2.95 $3.95 $19.95 $55.00 $19.95 $14.95 $34.95 $32.95 $3.95 $29.95 $19.95 $10.95 $39.50 $7.95 $27.95 $22.95 $22.95 $22.95 $25.00 $35.00 $35.00 $35.00 $35.00 $39.95 $16.50 $1.00 $1.00 $69.95 $199.00 OP5054 QP5515 OC7t60 RCli285 RCli296 SB2504 TS1476 TS1581 TH1902 TH1906 TH1908 XR1028 YX2500 YX2503 YS5512 YT6540 ZR1160 Z\/1625 Z\/1645 ZD1761 ZD1762 ZT2185 ZT2227 ZT2305 ZT2309 ZT2360 Zl3307 Zl3326 Zl3566 ZL3710 Zl3756 Zl3762 Zl3911 ZC4006 ZC4462 ZC4512 ZC4572 ZC4580 ZC4581 ZC4582 ZC4583 $9.95 $5.50 $29.95 $5.50 $5.50 $2.25 $79.95 $9.95 $17.95 $12.95 $23.95 $129.95 $44.95 $17.95 $39.95 $34.95 $3.20 $10.95 $32.50 2~ Centre Zerto Tuning Meter Lascar DPM Case ltttle Professor Calrulator 8.867238 Mhz Xtal 20MhzXtal GS Watch Battery Adcola Desol Tool Sutt Stat Tip for Scandia Desolderer Wre Brushes for Supertool Grinding Bits for Supertool Diamond Engrav for S/tool Robot with Remote Solar Exhaust Ventilator Solar Plant Turntable Pest Repeller Dual Element STD BI ode for Telephone 5082 - 2800 Schottky Diode LM337K 2 · '3fN Reg LM396K 1.5-15V Reg LEDSqRed5x5mm LED Sq Green 5 x 5 mm BCY71 Transistor MFE131 2N3442 2N3565 2N5245 LM307 LM326 NE566 UA709 Roood MC1496G CA3028 LM3911 4006 4426 4512 4572 4580 4581 4582 4583 NEWKIT FM WIRELESS INTERCOM FOR MOTOR BIKES ~ 95t 4(¥ $4.20 $5.50 $2.00 $2.50 ~ ~ Bot $1.95 $1.50 $1.00 $1.95 $1.00 $4.40 $2.50 $5.50 $1.35 $2.90 $1.95 $1.95 $4.95 $2.95 $2.90 $1.50 ~ ~ $1.20 ~ $2.00 $1.50 $2.95 85t $1.60 ~ Bot $2.00 $2.00 $1.25 $4.75 $1.10 $1.40 $1.95 ~ 3~ $1.00 $2.95 60t $1.45 $1 .45 $1.20 $3.95 $1.85 $1.85 $1.40 $1.40 $3.95 $2.20 $1.85 $2.95 $2.95 $1.75 $1.25 ~ ~ ~ 6~ 6~ 5~ $1.00 ~ 80t ~ 6Qt $1.00 Bot Bot $1.00 $1.00 Bot ~ Bot 40i 40i 2Qt $4.95 ~ $9.95 $1.95 $3.20 $1.95 $11 .95 $9.95 $8.00 ~ 40t $1.40 $1.00 $6.95 $3.95 $1.00 0.4mm Single Core Hookup Wire SENSATION ... Telecom style hookup wire 0.4mm single core insulated. Save an absolute fortune over normal prices. 250m roll Cat. WH-3027 500m roll Cat. WH-3028 ~ $4.95 $8.95 FEATURES PLUS . 20 Ranges · 34 Ranges -10AMPS • Diode Checker -10AMPAC & DC • Continuity Buzzer • 20 MHz Logic Probe • Capacitance Tester • Frequency Counter • Diode Tester • One hand Operation WASd$s9:9s See catalogue for full details HUNGCHANG20MHZCRO SAVE $,0 ONLY$49.95 ~ • Wide bandwidth and high sensitivity• Internal graticule rectangular bright CAT• Built in component tester• Front panel trace relater• TV video syno filter - Z axis (intensity modulation)• High sensitivity X-Y mode• Very low power consumption• Regulated power supply circuit $699 Probes to suit Cat. OC-1902 40t94 74HC90 74C02 74LS09 74LS49 74LS78 74LS95 74LS107 74LS126 74LS148 74LS155 74LS156 74LS158 74LS160 74LS166 74LS173 74LS190 74LSI 96 74LS243 74LS258 74LS365 7437 7475 7495 Z80AS10 8T-26A/MC6880A 81LS95/74LS795 81LS97 S-576A MCl3020 MC14411 SAVE ON DIGITAL MULTIMETERS Cat. OM-1410 DIGITAL THERMOMETER ZC4594 ZC4838 ZC4902 ZS5009 ZS5049 ZS5078 ZS5095 ZS5107 ZS5126 ZS5148 ZS5155 ZS5156 ZS5158 ZS5160 ZS5166 ZS5173 ZS5190 ZS5195 ZS5243 ZS5258 ZS5365 ZS5837 ZS5875 ZS5895 ZZ8015 ZZ8082 ZZ8195 ZZ8197 ZK8822 ZK8862 ZK8{1:;8 ECONOMY Ref: Silicon Chip October 1989 Will provide communications between rider and pillion passenger. or between riders on seperate bikes. Communicate with more than one rider at a time. and also includes and FM stereo. Cat. KC-5058 Cat. OC-l!nl $4.95 $1 .00 $19.95 $2.00 $2.00 $1.00 $49.95 $4.00 $12.95 $8.95 $14.95 $59.95 $29.95 $10.95 $19.95 $19.95 $1.00 $5.95 $19.95 1~ 1~ $49.50 ea Cat. OM-6300 Forget those old mercury thermometers. This digital model will measure body temperature from 32 • 43°C. Easy to use, simply hit the button to switch on. put in mouth or under armpit and when body temperature is reached, it simply gives a 'beep' to tell you.We have seen these in other catalogues for as much as $29.95. WAS $99.95 NOW $89.95 SAVE $10 PLUG-IN TIME SWITCHES Ideal for security Lighting. Cooking Appliances, Electric Water Heaters. Electric Radiators, Swimming Pools, Spa Heating, Pumps, Garden Lighting, Air Conditioners, Display Lighting, Electric Blankets, Radios, TV's etc. 24 Hour Cat. XW-0400 $31.95 7 Day MOTOR/GEARBOX KIT The kit contains a motor with press-fit brass cog, gearbox housing, 3mm x 110mm steel driveshaft, 2 intermediate shafts, 7 gearwheels and 6 nylon bushes. The motor will run from a source of 1.5 - 4.5 volts DC. A typical gearbox arrangement is shown in the exploded drawing. Cat. Y0-2712 Very compact 56 x 56 x 15mm Self starting one second stepping motor ■ Powered by 1 x AA battery that lasts about 1 year ■ ±15 second/month accuracy ■ Supplied with three sets of hands ■ Includes sweep second hand Cat. XC-0100 ■ ■ $12.95 $18.95 Cat. XW-0405 $32.95 REDUCTION TABLE Y0-2712 No. of gears 1.5V rpm 3V rpm 4.5V rpm 6 2 4 6 5 4 5 16 44 150 400 10 32 88 300 800 14 45 125 410 1150 3 2 1 PENDULUM MOVEMENT/QUARTZ CLOCK **** Ideal clock mechanism replacement for a small pendulum clock or create your own pendulum. ■ 3 sets of hands supplied ■$16.95 UseslxAAbattery Cat. XC-0103 MELODY CLOCK MOVEMENTS Two different modules are available. Both chime the hour after playing their tune. XC-0106 plays westrni nster Chimes each hour then gongs the hour (ie. 7pm - 7 gongs). XC-0107 plays a different melody each hour, then gongs the hour. Both units are supplied with: ■ Clock movement ■ Speaker and battery holder (3 x AA batteries required) ■ 3 sets of hands Cat. XC-0106 Westminster Chimes Cat. XC-010712 melodies RECHARGEABLE FLOURESCENT LANTERN FAMOUS ARLEC BRAND FEATURES: ■ 360° fluorescent glow and down light illuminates the area all around the lantern. ■ Charges from a regular household power point (240 Volt) or the cigarette lighter socket in your car (12 Volt). ■ Bright fluorescent light provided by two 6 watt and one 4 watt tubes. ■ High efficiency light inverter. ■ Up to 8.5 hours operating time. ■ Safe lighting for tents, boats, the bush and for children - no fuel or 'flames'. ■ Built-in and sealed, rechargeable lead acid battery. ■ ■ Overcharge protection circuit. 12 month guarantee. $89.95 $19.95 ARLEC CAR BATTERY CHARGER Features: ■ 4amp RMS ■ Charging meter ■ Overload and short circuit protection ■ Plastic case ■ 2 year guarantee Cat. MB-3520 $39.95 ARLEC RECHARGEABLE SUPER TORCH FEATURES: Charges from a household power point (249 Volt) or the cigarette lighter socket in your car (12 Volt). ■ Three large capacity nickel cadmium batteries (built-in}. ■ Wall mounting bracket. ----~.,/"-=lft;r ■ Reflector head that swivels through 00° for hands-free use. ■ Optional "dim" or full "on· settings. ■ Indicator lamp which glows when charging. ■ Rugged plastic case. ■ 12 month guarantee. Cat. ST-3005 FEATURES: ■ Never Buy Batteries Again . ■ Rechargeable from a regular household power point (240 Volt) ■ Built-in charger unit ■ Brilliant Krypton beam ■ Strong magnet for storage or hands-free use ■ ■ strap~fj~ Spare globe supplied Strong plastic case ■ Lightweight and compact ■ 12 month uarantee $27.95 $39.95 MERRY CHRISTMAS TO ALL OF OUR VALUED CUSTOMERS AND A HAPPY NEW YEAR FROM ALL OF THE STAFF AT JAYCAR ■ Quality woven wrist This great iron has all the features of those costing a lot more. • 240 volt operating • 370°C fixed temperature • High efficiency patented heating element • Iron clad chrome plated, long life interchangeable tips. Cat. TS-1550 ■ Cat. ST-3010 ARLEC SMART LIGHT 20WATT PROFESSIONAL SOLDERING IRON $19.95 CORDLESS TELEPHONE FEATURES: Simple to use and easy to install - just plug-in • ■ Operating range up to 250 metres (800ft) ■ Security code system with 16,348 combinations ■ Call function at base unit to alert handset ■ Pulse dialling with audible tone feedback at the touch of a ■ • 0 Cat. YT-7065 ,. - _- ONLY $179 NEW WATERPROOF MODEL $299° ¥8,t --- · ;,___~~· ,.,,,..< . . ] The Sensational 30 Piece 11 : 1 Engineers' Driver Set S bl t1 l o rSlot1 e d ec re w• CD t i-- o!, RADFAX DECODER INCLUDES ALL OF THESE PIECES: ---..P--- Sbit•fQr H e x acre we /: At last! A driver set incorporating those obscure (I) ~ ~ ~ shaped heads! This set contains all the drive r bits you are EVER li kely ' "" '~'"'"'"'"'"' "":::l::::g: '-P c:::l.,:a• f.. I ~ to encounter. Q7 ■ 5 slotted bits 0-1 , 3-4, 5-6, 8-10, 12 ■ 5 Hex bits 3/32", 5/64", 7/64", 1/8", 8/64" ■ 4 Phillips bits No. 0, 1, 2 & 3 ■ 4 Square Recess bits No. 0, 1, 2 & 3 ■ 6 Torx bits TlO, T1 5, T20, T25, T30, T40 ■ 2 Pozidrive Bits No. 1 & 2 ■ 1 x 1/4" Drive Socket Adaptor ■ 1 x 1/4" Drive Hex Bit Holder And it's all housed in a sealable tough plastic case.":~.;.~:~••<at>44 Cat TD-2000 .~~ ~ , E:::;:;~ t 6' - 3 STILL ONLY $19.95 ROVER NEGATIVE ION GENERATOR PIR DOORWAY/MINI ALARM <at>: These units are 240 volt operated, draw (: about 1/2 watt. del iver about 250 billion ""'= ions per sec ond, an d cover about 25 square metres. It's even supplied with a tester PC board and spare needles. These were selling for about $80. Jaycar has a limited qua ntity available. Cat YX-2905 e This pocket size alarm has a built in PIR sensor to detect human movement. It is ideal as a personal alarm or a shop door monitor. It will either give a pleasant chime to announce customers. or an alarm sound. It's easy to install . and measures only 108mm x 67mm x35mm. It operates on a9voltbattery. Cat. LA-5012 ONLY $49.95 ONLY $25 NEW RP/RB ELECTROLVTIC MADNESS KEYLESS ALARM PANEL SAVE $20 ONLY $199 Another surplus buy. which saves you a fortune. High quality Japanese made Nippon Chemicon brand. Normal Price l,300uF 63V RB $7.50 l.300uF RP $8.50 4,700uF 63V RP $8.50 6,800uF 40V RP $8.50 10,000uF 35V RP $11.00 See the Jaycar catalogue for full detai ls and our complete range of alarm equipment. Cat LA-5168 aov Sale Price 10+ $3.95 $4.95 $4.95 $4.95 $5.95 $3.50 ea Cat. $4.50 ea Cat. $4.50 ea Cat. $4.50 ea Cat. $5.50 ea Cat. •►►►- - -~ - :::-. . RU-6730 RU-6731 RU-6732 RU-6734 RU-6735 STEREO CEILING SPEAKER KIT This is a complete system ready to install in your home. It consists of: 2 x 4' dual cone quality speakers • 2 x Speaker grills and screws • 1 x 60W stereo volume controller • 2 x 20m rolls speaker wire. Ideal for games room. bedroom, kitchen, den, etc. Simply connect to your Hi-Fi system auxiliary speaker outlet. Full connection diagram supplied. Easily installed with simple hand tools. Cat. AS-3050 ONLY $99.50 ELECTRONIC SENTRY A complete burglar alarm in a PIR. What a great idea. Basically. it looks like a standard PIR but, it has a key swi tch on the front. It's completely self contained and needs no installation. Can be wall mounted or free standing. Incorporates built in sound maker giving a scream in excess of 85d8. Battery operated. Ideal simple burglar alarm for homes. units, caravans, garages, boats, shops, offices, etc. SPECIFICATIONS: Installati on Free standing or wall mount Operation By key Normal Operating Height 0.5 • 2 metres Operation Power requirement 9V Alkaline battery Standby Arming Delay 2 minutes Entry Delay 15 seconds Alarm Period 1 minute Siren Volume In excess of 85 dB Reset and Rearm Automatic Low Battery Indication Short 'beep' at 10 seconds interval Cat. LA-5015 Was$99.95 SAVE $10 ONLY $89.95 JAYCAR SOLDERING KIT Designed for general purpose soldering. This kit includes a 30 watt 240 volt soldering iron. a quality metal stand with sponge, a length of solder and a roll of solderwick. Cat. TS-1650 $29.95 BUT 1989 148 page PLEASE catalogue ASK Free with every purchase HIGHER POWER DATABANK/ CALCULATOR Similar to OM-7200 but• 16 character alpha-numeric LCD display• Capacity 8000 alpha-numerics • Superior editing or old information • Soft rubber tactile keypad • 14 digit calculator with memory• Character search• Forward search Only requires 4 x AAA batteries. Measures 155 x 103 x 35. Very high performance unit! 0 This personal databank will store your telephone numbers as well as being a pocket calculator. The databank has 2K memory which is 1,936 characters which will accommodate more than 100 names and telephone numbers. It measures only 88 x 57 x 4mm thick, about the same size as a credit card. It also has a special security code, so those private phone numbers can't be retrieved by anyone but you. $59.95 Cat. OM-7206 JTYPE THERMOCOUPLE PERSONAL • DATABANK/·· CALCULATOR ~ ~ UNDER $40 GREAT CHRISTMAS GIFT!! Save a fortune. Wholesale price $30!- tax +Ve composition Fe -Ve composition Ni 40-43% Balance Cu (Constantan alloy) Cont. Temp. Range -200°C to 870°C Max Spot Reading 1100°c Accuracy 0°c to 300°C ±% 300 to 780°C :t"C Cat. ZT-8400 Were selling for $20 NOW ONLY $10 BACKWARD CLOCK MOVEMENT Other features include: • Auto power off• Edit feature Cat. OM7200 • 10 digit calculator• Includes battery We have seen these for as much as $79.95. But with our direct importing we can offer them at about 1/2 that price. SCREAMER BARGAIN • SAVE 44% Don't pay over $40 for a backward clock. Make your own. A great idea and extremely baffling at first when friends try to figure out what time it is. The hours on the clock face should be reversed as the hands go backwards. Guess the time !! It's 5 past 3. Supplied with 3 sets of plastic hands. Requires 1 x AA battery. Made in Italy - grey in colour. 12 volt with unbearable sound. Size 57L x 33H mm. Cat. LA-5254 WAS $17.95 NOW $9.95 15" 150W RMS Guitar Speaker 80mm dia. Voice coil. Cat XC-0102 Cat CG-2382 $14.95 Onl $129 j. ; .0i' WAS $39.95 ,,,,1 e1 .- - ·- . ~ ,k ,.,;!; / TECHNICIANS BRIEFCASE Another distress stock buy, well below normal price. It's metal. hammer tone grey in colour. and has an ABS insert which sits nicely inside to hold all those components. It has 20 small compartments 50x55x35 deep mm and one large compartment to hold screwdrivers. cutters etc. The lid closes tightly, so components won't spill into the next compartment. It is well built. so will handle rough treatment. A handle is supplied along with a card holder for identification. Total size is 340mm wide x 240mm x 45mm thick. Normal price would be about $25 We can offer these at an absolute bargain basement price of only $12.95 each 5 + $12 each Cat. HB-6320 C& 0 Ni Cads SAVE UP TO 42% A must for people learning music. Fully self contained electronic style. Tempo is variable from 40 to 208 beats or times per minute. Switchable between audio sound and a Red LED. Supplied with an earphone for private use. Battery operated Size 60 x 108 x 30mm Cat. OM-7240 Was $11.25 ea NOW $6.50 EA Cat SB-2459 SUNRISE BRAND 10+ $13.95 Cat SB-2482 2.6AH $19.95 10+ $18.95 Cat SB-2484 15AH $59 WAS $79 10+ $55 Cat. SB-2490 1.2 Ah D size Was $11.98 ea NOW $6.95 EA MAIL ORDERS POST & PACKINO 115 Parramatta Road Concord 2137 P.O. Box 185 Concord 2137 HORINE 02 747 1888 Telephone (02) 747 2022 FACSIMILE (02) 744 0767 FOR ORDERS ONLY TOLLFREE (008) 022 888 $l0-$2 _ 4 99 $25 - $49_99 $50-$99. 99 OVER $100 MAIL ORDER VIA YOUR VISA PARRAMATTA CONCORD HURSTVILLE HUNDREDS OF USES AROUND THE WORKSHOP OR FOR HOBBY USE ~ Cat. SB-2460 HEAD OFFICE ffi EXIDE 12 VOLT GEL BATTERIES 1.9AH $14.95 C size $39.95 SYDNEY - CITY SAVE $5 ONLY $34.95 117 York St. (02) 2671614Mon-Fri 8.30 - 5.30 Thurs 8.30 pm - Sat 9 - 12 355 Church St (Cnr. Victoria Rd) (02) 683 3377 Mon-Fri 9 - 5.30 Thurs 8.30 pm - Sat 9- 4pm 115 Parramatta Rd (02) 745 3077 Mon-Fri 8.30 - 5.30 - Sat 8.30 - 12 121 Forest Rd (02) 570 7000Mon-Fri 9 - 5.30 Thurs 8.30 pm - Sat 9- 12 ff ROAD FREIGHT ANYWHERE IN AUSTllAUA $13.50 GORE HILL BU RANDA QLD MELBOURNE-CITY SPRINGVALE VIC $ .7 3 5 $ 4_50 $ 6.50 $800 188 Pacific Hwy (Cnr. Bellevue Ave)(02) 4394799- Mon-Fri 9 - 5.30 Sat 9- 4pm 144 Logan Rd (07) 393 0777 Mon-Fri 9 - 5.30 Thurs 8.30- Sat 9- 12 Shop 2. 45 A'Beckett St City (03) 663 2030 Mon-Fri 9 - 5.30 Fri 8.30- Sat 9 - 12 887-889 Springvale Road Mulgrave (03) 547 1022 Nr Cnr. Dandenong Road Mon-Fri 9- 5.30 Fri 8.30 - Sat 9 - 2 IPRODUCT SHOWCASE l Plastic backshells for DB25 connectors Helmet to helmet motorcycle intercom For those who don't have time to build our wireless motorcycle intercom published in the October and November issues of SILICON CHIP, this unit will be of interest. It will .l et the rider communicate with the pillion passenger without screaming. Called the Bikemike, it is a cigarette packet-sized unit with two coiled leads running to iri-line 3.5mm sockets. Each of these are connected to two earpieces and a microphone which are taped inside the helmets with Velcro pads. When not being used as an intercom, a W alkman can be plugged in to give music on the move. The unit has low current consumption and runs from a 9V battery. The cost of the Bikemike is $69.95. It is available from all Jaycar Electronics stores. -Stereo FM transmitter kit uses surface mount chip Tiny dome tweeter from Altronics This new dome tweeter is ideal for use in compact speaker systems. Manufactured in West Germany, it is only 60mm in overall diameter and 17mm in depth, yet it is rated at a very respectable 40W. With a claimed frequency range to 20kHz, the unit has a resonant frequency of 2.9kHz. To obtain the power rating of 40 watts, the suggested crossover frequency is 7kHz with a . crossover slope of 12dB per octave. Nominal impedance is 8 ohms and the deviation from this value is remarkably small over the If you have a computer which uses non-standard wiring for the printer port you probably have bare DB25 plugs and sockets which look messy and unprofessional. This attractive backshell will allow you to clean up your act. Either male or female connectors can be fitted to either end of the shell, allowing the wiring to fit neatly inside. ' Priced at only $3.25, it's well worth cleaning up that rat's nest of wiring. They're available from Geoff Wood Electronics, 229 Burns Bay Rd, Lane Cove, NSW. Phone (02} 428 4111. range to 20kHz. Rated sensitivity is 89dB at 1W, 1 metre. The tweeter is priced at $39.95 and is available from Altronics Distributors Pty Ltd, 174 Roe Street, Perth, WA 6000. Phone (09} 328 2199. For those who want to build a version of the Stereo FM Transmitter with a difference, Dick Smith Electronics has a kit which will appeal. Originally described in the October 1988 issue of SILICON CHIP, this very popular mini FM transmitter project used an 18-pin IC which has occasionally been in short supply. Recognising this, and taking advantage of the easier supply, Dick Smith Electronics has redesigned the printed circuit board to take a surface mount version of the chip. We must say that their version of the board is very neat and provided you are reasonably careful when DECEMBER1989 105 You simply insert the AA cell inside the C or D size adaptors and then place the adaptor into the battery compartment. We found the design of the C size adaptor more positive in its grip of the AA cell than the D type but both will find wide use in equipment with rechargeable batteries. The cost for both adaptor sizes is $4.95 per pack of four, from all Jaycar Electronics stores. Digital multimeter has frequency and capacitance Security/courtesy light uses PIR detection This unit is ideal for those dark walkways, where light is the best form of protection. It uses a passive infrared detector (PIR) to automatically turn on the accompanying floodlights (500W max.) when it detects rapid changes in temperature from a moving object (eg, a person or car). The sensitivity can be adjusted to between 6 and 15 metres. It is fitted with a timer adjustable between 1 and 20 minutes which, after being triggered, turns off the floodlights after the set time. The unit also has an in-built photocell which turns it off during the day. The unit comes with an installation and operation manual and mounting bracket but without the floodlights, allowing you to match the light for a given area. Priced at $135, the PIR Security Lamp is available from Altronics Distributors Pty Ltd, 174 Roe Street, Perth, WA 6000. Phone (09) 328 2199. soldering, it will present few problems in assembly. We tested a built up sample of their kit and found it performed slightly better than our original prototype. It ,also has a good quality label which enhances the ultimate appearance of the project. Priced at $34.95, the FM Stereo Transmitter kit (Cat. K-5004) is available now from all Dick Smith Electronics stores. Nicad AA cell holders If you have portable equipment requiring the C or D size rechargeable nicads and plenty of AA cells, then these new nicad battery adpators may solve a problem for you. They allow you to use AA cells 106 SILICON CHIP in place of C or D sizes. Sure, you will get less discharge time because of reduced capacity but AA cells are a lot cheaper and more readily available than the larger sizes aren't they? Digital multimeters continue to get better and better all the time. This attractively styled model from Escort features 4000 count (rather than the normal 2000 count) and an analog bargraph to simulate the pointer of an analog meter. Designated the Escort Model EDM-1177, it has autoranging for volts AC and DC, Ohms, millivolts AC and DC, and AC and DC current. As well, it has autoranging measurement of capacitance with ranges from 4 nanofarads to 40,000 microfarads and the ability to measure frequency up to 400kHz. There are 5 voltage ranges from 400mV to 1000V for DC and 400mV to 750V for AC volts, with an input impedance of 10MQ on both. DC voltage accuracy is ± 0.3 % of reading while for AC voltage it is ± 1 % of reading. Toroidal transformers from Harbuch Electronics While there are a number of suppliers of toroidal transformers in Australia, none have complied with the Australian Standard C126 with respect to separation of the primary and secondary windings. That is not to say that they are faulty. However, this new range of Antrim toroids has the primary and secondary terminations brought out at different points on the transformer circumference, thereby increasing the isolation between the two windings. Prices for these transformers start at $32.80 (tax paid) for the Current ranges for AC and DC are 400µA and 10A in 6 ranges with ± 1.5 % accuracy for DC and ± 2% for AC. When measuring capacitance, the accuracy is ± 5 % of reading for the 4nF and 40,000µF ranges and ± 2 % of reading for the other 6 ranges. For frequency measurements, the minimum sensitivity is l00mV RMS and the accuracy is typically ± 2% of reading. The unit also has data and peak hold functions which store the last value displayed or the peak value measured. Recommended retail price is $248.00 (incl. tax), complete with test leads and instruction manual. The Escort EDM-1177 is available from David Reid Electronics. Phone (02) 267 1385 or call in at 127 York Street, Sydney. Trackmate disc drive cleaner has diagnostics This is a disc drive cleaner with a difference! Not only does it clean your drive but it also can do diagnostic checks with a menu driven software package. You simply insert the program disc and the computer selects and 15VA version and range up to $112.00 for the 625VA size. For further inforamtion, contact Harbuch Electronics Pty Ltd, 90 George Street, Hornsby, NSW 2077. Phone (02) 476 5854. for IBM PCs and compatibles and for the Apple Macintosh. The cost for either package is $59.95 and both are available from Grace Bros and Myers stores or contact Trackmate Australia Pty Ltd, Suite 1, 1 Johnston Lane, Lane Cove, NSW 2066. Phone (02) 427 3999. Temperature probe set has plug-in handle !,•.,/ L e, controls the correct cleaning routine for your drive. You then insert the cleaning disc and the computer controls it to clean the read/write heads. The cleaning disc surfaces clean both the heads and the disc guides and they can be washed for re-use. The software disc not only tells you that your drives are within specification (or are not) but it also keeps a record of test and cleaning results. The package is suitable for cleaning drives 110 times which is a great deal more than the usual cleaning disc. The package is available in either 3½-inch or 5¼-inch format Now available from Amalgamated Instrument Company is this utility temperature probe set. Each set comprises one probe handle and three plug-in probes: one surface probe, one air probe and one liquid immersion probe. The probes can be supplied separately and are available in K and J type thermocouples. For further information, contact Amalgamated Instrument Company, 7/21 Tepko Road, Terrey Hills, NSW 2084. Phone (02) 450 1744. DECEMBER 1989 107 Safety first for faxes & modems As many people found out last summer, thunderstorms and mains spikes can cause very expensive damage to modems and fax machines. If the main board on a fax machine goes, you can be up for a very big bill indeed. And if your modem gets a surge, you may as well drop it in the dirt tin. Fitting a mains suppressor is no help at all and may even make the situation worse because the really severe transients come in on the phone lines. This means that both the phone lines and the mains lines need protection. Up till now though, suitable protective units just have not been available. Now there is an answer. Arista has just released their fax/modem filter which has transient suppression on both the phone · lines and mains lines. For really effective protection it incorporates gas arrestors on the phone lines and Fujitsu FPG-316 intelligent colour plotter When you first take the Fujitsu FPG-316 ImageGraph plotter out of the carton it looks more like a printer than a 6-pen plotter. There are two reasons for this. First, it is not a flat bed plotter on which the pens move up, down and across the paper. Instead, it works by moving the paper back and forth under the pens. This makes it much more compact although when working it tends to take up almost the same amount of space as an equivalent A3 plotter because of the paper guides fitted to each side. Without the paper guides it measures only 420mm MOVs (metal oxide varistors) on the mains lines. It comes in a neat moulded plastic case which plugs directly into a mains power socket. The fax or modem is then plugged into it. On the side are two US-style modular phone sockets, one for the incoming phone line and the other for a standard Group 3 fax connector. Three neon lights are included to indicate power and correct wiring of the power outlet. So now you can reduce the wide, 260mm deep and 95mm high. Its weight is 4.5kg. It comes with parallel and serial interfaces or can be supplied with a GPIB (IEE-488) interface. The second reason why the FPG-316 plotter looks more like a printer is that the pen holder is hidden in a compartment on the lefthand side. You unclip the cover from this compartment, load up to six pens of different colours into their respective positions in the rotary pen holder, load the paper or drawing film according to the instructions, and you are ready to go. o) FUJITSU 6 COLOUR PLOTTERS * Parallel and Serial Interface - GPIB also available * High Quality Re solution 0.025mm * Compact and Lightw eight 420 X 260 X 95 mm - 4.5 Kg * Wide Selection of Paper Sizes A3 down to Postcard * Wide Application s Business, CAD, Hobbyists etc. FPG316 PAR/SER - $1,299.00 FPG316 GPIB - $1,350.00 +20% Sales Tax.$10 Delivery Pacific Microelectronics Pty.Ltd . Unit A20 I 4 Central Avenue P.O. Box 189 THORNLEIGH N.S.W. 2120 Telephone 02 481 0065 FAX 02 484 4460 108 SILICON CHIP It took quite a lot of fiddling about (with DIP switch settings) to get this plotter to run with our CAD system running on an AT compatible but once this was accomplished we can report that it gave good results. We tried it both with text and CAD output. It works with plastic and fibre tip pens, as well as with ballpoint water colour pens. Pens are automatically capped when placed back in the holder so that drying out problems are kept to a minimum. The resolution is quoted as .025mm and is certainly more than adequate for•most plotter applications. The Fujitsu FPG-316 with serial and parallel interfaces is priced at $1299 plus 20% sales tax where applicable. For the version with GPIB interface, the price is $1350 plus sales tax. For further information on Fujitsu plotters, contact Pacific Microelectronics Pty Ltd, Unit A20/4 Central Avenue (PO Box 189), Thornleigh, NSW 2120. Phone (02) 481 0065. 3½-digit capacitance meter hazard to faxes , modems and computers from the double whammy of transients on phone lines and mains wiring. The price? Just $59.95 from all Arista stockists. For further information, contact Arista Electronics Pty Ltd, PO Box 191, Lidcombe, NSW 2141. Phone (02) 648 3488. If you have trouble reading the codes on capacitors or you have caps with the labels rubbed off, it is so convenient to be able to measure them on a capacitance meter. Many digital multimeters now feature capacitance measurement but they can rarely handle the full range of values in normal use. This new capacitance meter provides nine ranges between 200pF and 20,000µF and a zero adjus t ment for the l ow capacitance ranges (ie, 200pF, 2nF and 20nF). Accuracy is ± 0.5% of reading + 1 digit for the 7 ranges from 200pF to 200µF, ± 1 % + 1 digit for the 2000µF range and ± 2% + 1 digit for the 20,000µF range. Over-range and low-battery indicators are also given on the display, which updates itself at the rate of about twice a second. The new capacitance meter is priced at $109.95 complete with instruction manual and test leads and is available from all Jaycar stores. 12V/2A power supply for CBs and car radios Ceiling loudspeaker grill looks like a downlight This hew power supply is designed for use with CB's, car radios, alarm systems and DC power tools and provides a regulated 12 volts DC at up to 2 amps output. The unit is fitted with 4mm banana socket/ terminals and is double insulated. Price is $69.95 from Altronics Distributors Pty Ltd, 174 Roe Street, Perth WA. Phone (09) 328 2199. Digital voice board ctd from page 31 This loudspeaker grill is designed to look like a downlight and could find many uses in homes and office buildings, shopping centres and restaurants, or anywhere normal speaker grilles are not wanted. They are only $3.95 each and are available in white or black. They are supplied by Altronics Distributors Pty Ltd, 174 Roe Str eet, Perth WA. Phone (09) 328 2199. power is disconnected. The battery pack can be secured using cable ties around it and through the holes on the board. You can check the operation of the comparators by turning the VR1-VR4 trimpots two thirds anticlockwise (from their maximum clockwise setting). Now switch S1, S3, S5 and S7 off and S2, S4, S6 and S8 on. Connect a jumper wire from + 5V to input 1 and check that memory LED 1 lights up after a brief pause (IC5 needs time to cycle round). Simila rly, check that memory LEDs 2, 3 and 4 also light when input 2, input 3 and input 4 are connected to + 5V. Once all functions have been tested, the Voice Board can be installed in its final location. First select the options for switches 1 to 8. Switches 2, 4, 6 and 8 select the inputs while switches 1, 3, 5 and 7 select the polarity of the input. For "low to high" signal triggerings, these odd numbered switches should be off while for "high to low" signal triggering the switches should be on. Unused inputs can be left with the switches off. ~ DECEMBER1989 109 MONITOR MOVER ARM Position your monitor exactly where you want it! Place your monitor in an ideal working position, or out of your way when you're not using it. Maximise desk space! • Solid steel structure • Height adjustment by knob (3cm-27cm) • Span 33cm • Tray 30cm (tilting +/-1 5°) • Desk clamp range 3cm-7.5cm • Maximum load 50kg All sales. tax exempt orders and w_holesale inquiries to : RITRON ICS WHO LESALE 56 Renver Road. Clayton. Phone:(03) 543 2166 (3 lines) Fax: (03) 543 2648 UPGRADE YOUR COMPUTER WITH A 3 1/2" DRIVE KIT Y.E DATA 3.5" 1.44/ 720/ 360 DRIVE • 5 1/4" Mounting bracket • Power supply adapter • Floppy Disk controller card which controls 1.44/ 720/ 360/ drives • Cable adapter Complete instructions to install a 3.5" drive in your existing computer. Enjoy the higher density and easy handling of 3.5" Floppy diskettes. .............. ... ...... ONLY $355 ► POSTAGE RATES : $1 - $9.99 ........ ................. $2.00 $10 - $24.99 .. ...................$3.00 $25 - $49.99 .....................$4.00 $50 - $99.99 .....................$5.00 $100 + .............................. $7.50 The above postage rates are for basic postage only. Road Freig~,i. bulky and fragile items will be charged at different rates. Errors and omissions excepted . Prices and specifications subject to change. IBM' PC' XT' AT ' are registere d lldliPmarks 01 l nterna1 ,onal Business M ac hines "App lP. ,s ,1 11,g 1~te rP.d tra dema1 k Te!lon· 1s a reg 1ste rn1 1r ;id ema , k. ol Dupont · □ eriontes ,eg ,~1 c rf' r:I 1raC1llmarkso11he1rres pect1veowne•s G7 MONOCHROME COLOUR CARD • IBM' Colour Graphics Adapter compatible (support 600 x 200 four colour graphics model) • IBM' Monochrome Display Adaptor compatible • Hercules Monochrome Graphics Adaptor Compatible • IBM' Printer Adapter compatible • Support Composite Monochrome monitors BABY AT* COMPATIBLE COMPUTER! 2 M/BYTE RAM ONLY $2,195 • Final assembling and testing in Australia! • 4 M/Byte ·Main Board, 2 M/Byte fitted • Switchable 8/10/12 MHz • 1.2 M/Byte Floppy Disk Drive • 80286 CPU • Colour Graphics Display Card • 8 Slots • Floppy & Hard Disk Controller • Printer Card and RS232 • Keyboard • 200W Power Supply • Manual • 6 Months Warranty • Size: 360(W) x 175(H) x 405(D)mm With 20 M/Byte Hard Disk.$2,195 With 40 M/Byte V.C. H.D.... $2,395 With 80 M/Byte Hard Disk .. CALL PRINTER CARD Parallel interface for Centronics printers. X18017 ............. .......... $29 3.5 M/BYTE EXTENDED/ EXPANDABLE RAM AT* CARD X18056 ..................... $275 X18007 ................ ..... $139 1/0 PLUS CARD GRAPHICS CARD Provides a serial port, a parallel port and a joystick port . and even a clock/calendar with battery backup! TTL and Hercules compatible with printer port X18003 ... ....... ............. $99 ENHANCED GRAPHICS ADAPTOR CARD Auto switch CGA, EGA and Hercules with 256K Video Ram X18045 .... .. .. .. .. .. ....... $115 2 M/BYTE EXTENDED MEMORY RAM CARD X18052 ..................... $225 X18070 ..................... $295 VGA CARD PC'/ XT' / AT' compatible 256K Ram works with OS/2 VGA 512K PC' / XT' / AT' compatible 512K Ram. Hardware zoom, pan, window. X18072 ..................... $795 MULTI 1/0 & DISK CONTROLLER CARD This card will control 2 x double sided, double density drives, and features a serial port, a parallel port, and a joystick port or games port. It also has a clock/calendar genarator with battery backup SERIAL/ PARALLEL/ GAMES CARD FLOPPY DISK DRIVE CONTROLLER CARD R-NET/ S INTERFACE NETWORK CARD • Fully compatible with SMC, Novell Arenet card • Star-burst topology through RG-62 AIU coaxial cable • Zero wait at 20MHz or higher 80386 machine • 2.5 Mbps transmission rate X18162 .................... .$275 These cards will control up to 2 or 4 double sided 360K IBM' compatible disk drives For 2 Disk Drives X18005 ....................... $52 RS232 (SERIAL CARD) XT' / AT' c ompatible 1 parallel port, 2 Serial ports, 2 port games adaptor. X18151 .. ................... $115 4 WAY DISK CONTROLLER , PC'/ XT'/ AT' compatible • 1.44 M/B, 1.2 M/B, 720K, 360K Drives X18006 ..................... $129 WITHOUT CABLE Supports 2 asynchronous communication ports. 50 baud to 9600 baud. GAMES 1/0 CARD Features 2 joystick ports.(DB 15) X18019 ............ ....... .... $29 E-NET INTERFACE NETWORK CARD • Fully compatible withNovell NE-1000 Ethernet card • Built-In 15 pin D type connector • 1O Mbps transmission rate • Meets the IEEE 802.3 standard X18160 ..................... $425 WITHOUT CABLE Supports 1 asynchronous communication port. 50 to 9600 baud with Clock. X18028 ....................... $59 CLOCK CARD X18024 ....................... $49 The MIDI DS-401 Card is the PC standard MIDI interface that runs most popular PC music programs for sequencing, recording , composing , music printing , patch editing , music instruction and many other applications. • Run all programs designed for the Roland MPU-401 architecture • Socketed EPROM for easy user replacement • 113 length (short) card will fit in any computer accepting standard expansion card, including laptops • Including "Y" cable, external connector box to transport is unnecessary 386SX 16MHz MOTHERBOARD • Processor: 80386SX-16MHz (0/1 wait state) • Co-processor:80387SX-16 (optional) • CHIPS & TECH NEAT chipsets • (SMT) Surface Mount Technology for chipsets & CPU • Supports up to 2MB on board, (Sixteen 44256 and Eight 41256 sockets) • Three 8 BIT slots • Five 16 BIT slots • Memory Expansion Slot • Optional 2-8MB memory card • Supports LOTUS-INTELMICROSOFT (LIM) Expanded Memory Spee. (EMS) version 4.0 I • Supports Page Interleave Mode using 100NS DRAM • BIOS: AMI or PHOENIX • Turbo Light and Hardware Reset connector • Keyboard or Hardware Reset connector • Power Good Signal on board • Baby size main board •Without Ram X18094 ..................... $900 286 NEAT MOTHERBOARD X18026 ................ ....... $39 RS232 & CLOCK CARD MIDI INTERFACE CARD - DS/401 AC ADAPTOR • Output: 6V 300mA . M19008 ................ $8.95 1/0 ACCESSORIES X18164 ............. .. ...... $245 X18071 ..................... $595 X18040 ....................... $99 NETWORK CARD INCREDIBLE IBM* CARDS COMPUTER HARD DISK CONTROLLER CARDS X18060 (XT*) ............ $129 X18140 (AT*) ............ $195 • Processor: 80286-12, -16MHz or -20MHz (0/1 wait state) • Co-processor: 80287 (optional) • CHIPS & TECH NEAT chipsets • 1-4MB dual RAM socket • 1-4MB module RAM socket on board • 640KB-384KB memory relocation • Three 8 BIT expansion slots • Five 16 BIT expansion slots • Memory expansion to 8MB • Supports EMS 4.0 • Page Interleave Technology • BIOS: AMI or PHOENIX • Hardware and keyboard switchable Clock Speed • LED speed display • Power Good Signal on board • Baby size main board • 16MHz X18090 ..................... $700 • 20MHz X18092 ..................... $895 If you have two or four compatible devices that need to share a third or fifth, then these inexpensive data transfer switches will save you the time and hassle of constantly changing cables and leads around. • No power required • Speed and code transparent • Two/Four position rotary switch on front panel • Three/Five Interface connections on rear panel • Switch comes standard with female connector 2 Way RS232 X19120 .......................$59 4 Way RS232 X19125 ....................... $79 2 Way Centronics X19130 ....................... $69 4 Way Centronics X19135 ....................... $79 RS232 2 X 2 Auto Switch X19140 ....................... $79 Centronics 2 x 2 Auto Switch X19145 .......................$79 • Pocket size, Duto-scanning • Allows 2 PCs to share one Printer Serial model: MS-201 - Host-powered X19150 ..................$79.95 Parellel model: MP-201 Protocol transparent X19155 .................. $89.95 Manufacturer's data on the LM831 low voltage audio power amplifier National Semiconductor's LM831 is a dual low power audio amplifier optimised for operation at low voltages. It has two independent amplifiers, giving stereo or bridged mono operation. By DARREN YATES In the October and November issues of SILICON CHIP, we published an FM Radio Intercom which was mainly intended for communication between two or more motorbikes or between rider and passenger. One of the chips featured in the circuit is a new device from National Semiconductor, the LM831 stereo power amplifier. Although there are already a number of audio power ICs on the market, this one is different in a number of useful ways. The LM831 is a self-contained stereo power amplifier capable of driving loads as low as 4 ohms in either normal stereo (dual) opera- tion or in a mono power bridge (BTL) configuration. But what makes this 16 pin dual in-line (DIL) chip different is that it is optimised for very low voltage operation down to as low as 1.8 volts DC. The LM831 includes a patented compensation technique to reduce high frequency radiation, for optimum performance in AM radios. This compensation also reduces wideband noise and results in lower distortion. Main features The main features of the LM831 include: • Low voltage operation: 1.8 to 6.0 volts DC; • Typically 220 milliwatts output per channel into 40 loads or 440 milliwatts into 80 in bridge mode from a 3 volt supply; • Low AM radiation; • Low harmonic distortion typically 0.25% at 50mW; • Maximum gain: 46dB in dual (stereo) mode, 52dB in bridge mode; • System gain adjustable by external components; • Low quiescent current: typically 5 to 6mA. Both amplifiers can be connected in the inverting or non-inverting configurations and no input coupling capacitors are needed. Stereo operation A typical application for the LM831 is shown in Fig.2. It shows a stereo power amplifier which can drive 40 loudspeakers and run from just 3 volts. This could be supplied by two AA (penlite) cells. The gain of each channel is set internally by the 16k0 and 800 feedback resistors to 200. If need be, the gain can be easily reduced by connecting resistors in Typical Performance Characteristics Distortion vs Power Output Separation vs Frequency 11111 11 70 Ml u 50 z 0 i ~ •o IRAv • 2•on. Ctw • 270 pF) GAIN•C6 dB (R.1,ya.OO. C1w•O pF) ---- - r-,;;: ~ - - 10 kHz i !; i I.,._ ;;; t kHz ll 30 20 II Vout•200 mv I 1 11111 20 I 0.05 DUAL M OE 10 ~Yee• 3V, CH-A TO CH-8 0 SO 100 I 200 I I SOO 1K 2K FREOUENCY !HZ! 5K "" "" ,Hi:i .. 3,-. 111 l),EIJLe I 1111' .,, / Power Dissipation vs Power Output 10 10 10K 2DK 0.5 0.2 0.1 0.05 Ycc•3V, Rt•40 0.02 ~ C1w •RAv• 0 0.002 0.5 1 I ..,,. -~ Vcc•4V - :.,., ;..,- ~,; "' t1c•3V-- Vee• 2v 0.01 0.005 0.2 TH0-10 -;. Ill 0.02 ~ DUAL MODE I 1111 111 1 0.01 0.001 0.002 0.005 0.01 0.02 0.05 0.1 POWER OUTPUT IWATT) 1 Ycc•&V Vcc•5V ,-DUAL MODE 110TH DRIVE) Rt~•P·1 '1~111~Hz 0.001 0.001 0.002 0.005 0.01 0.02 0.05 0.1 0.2 0.5 1 POWER OUTPUT (WAIT) 2 5 Fig.1: these graphs show the performance of the LM831 in stereo mode. The chip can be operated on single supplies up to 6V DC and it generally performs with lower distortion at the higher voltage. 112 SILICON CHIP 500pF VIN 13 47 - +22~ O.JJJ LM831 4(l VIN 1D0 lOk>-,.....:.14;:_t.:...:l:,..N....;j..--1 ~SPEAKER .,. vs 1 I BY~q 9 47 47 VIN + 22+ 47 .,. SPEAKER GNDt +3V - .,. BSr VIN > + 10D - 1000 80(l 16k AV GND R 2--6--1 + +~ D.JJl ... 4(l ~SPEAKER 10! Fig.2 (above): this circuit shows how the LM831 is connected for stereo operation. Because the input transistors are PNP, no input coupling capacitors are required. Fig.3 (right): this is an improved version of the circuit ► shown in Fig.2 with bigger feedback, bootstrapping and output coupling capacitors. series with the external 101,lF feedback capacitors (ie between pin 2 and the ' capacitor for one channel, and between pin 15 and the capacitor for the other channel). For example, if a 2200 resistor is installed in series with the capacitor, the gain drops to about 54. Both channels are independent of each other and channel separatiqn is better than 52dB (with reference to lkHz). However, this figure drops quickly if the supply voltage goes below 2 volts. Maximum usable output power in the stereo mode is about 450mW into 40 per channel with a 6V DC supply. Total harmonic distortion at this power level is about 3% but at lower power levels it is typically around 0.5%. With a 3V supply, the maximum power per channel into 40 loads is about 220 milliwatts. The circuit of Fig.2 has a quoted frequency response of 250Hz to 35kHz. Fig.3 is an improved circuit with larger output and bootstrapping capacitors VIN DM8~0(l◄J :_-_-_-:~GN. . . ·.;......_ _ ]l!!!!.._IJG"-'N:::.D_ _ 2 .,.6 1 6 + ...JZ 11 ~ ~ 47r.- 15 + 10+ 0.1 Fig 4: here's how to connect the LM831 to drive a single loudspeaker in bridge mode. Note that, as far as we can determine, the 10µF feedback capacitor connected to pin 15 should be omitted although we have drawn the circuit as shown in National Semiconductor literature. and improved DC supply bypassing. It has a frequency response from 20Hz to 20kHz. Bridge mode In bridge mode, both amplifiers in the LM831 drive a single 80 load to get close to the same total power as the device can deliver into two 40 loads in stereo mode. You might ask, "Why bother'?" The answer is that the bridge mode delivers more DECEMBER1989 113 VIN Fig.5: this improved version of the bridge circuit uses bigger feedback and bootstrap capacitors. Again, we think that the 2400 resistor and 22,uF capacitor connected at pin 15 should be omitted. power into the most readily available speaker load (ie, 80) than can otherwise be achieved from a low supply voltage. The bridge mode also eliminates the need for output coupling capacitors which is an important point. In bridge mode, two power amplifiers are driven so that their outputs are 180° out of phase. When connected to a common load, the output voltages are added and so the effective power is quadrupled. In the LM831 however, the minimum load impedance that each channel can drive is 40, so the minimum load for bridge mode is 80. This is because each channel amplifier " sees" half the actual load impedance. Fig.4 shows the method of connecting the LM831 for the bridge mode. It requires a O.lµF capacitor to be connected between pins 1 and 13. This has the effect of making channel B work in the inverting mode with a gain of unity and with the signal coupled internally via a 16k0 resistor from the output of channel A. Because of the effect of signal addition, the maximum gain of the bridge mode circuit is 5 ZdB. Note that the 80 speaker is connected directly across the outputs and no output coupling capacitor is used. The maximum output power in this mode is close to 800mW into 80 at 3% harmonic distortion from a DC supply of 6 volts. At 3 volts, the maximum power is about 440 milliwatts into an 80 load. Overall bandwidth of the circuit of Fig.4 is quoted as 250Hz to 25kHz. Readers who saw the FM Radio Intercom project featured in the October and November issues may recall that in that circuit the LM831 was used to drive two 80 speakers in parallel, giving a load of 40. The LM831 will happily drive such a load although it will give no more power than it would into an 80 load. The reason we used two 80 speakers is that they are readily available and we wanted to have a speaker for each ear. While the LM831 works satisfactorily into a 40 load in bridge mode, ...---------------01 BOOTSTRAP tAI BOOTSTRAP (BI 120-,....-....----1---------BYPASS Vsum, JSO!! 16,o--------------Al OUTPUT (BI 10 ~.,_-+---+------+--+----l__,,.Y,,._I\N~-0 11 POWER GROUNO (II OUTPUT (A l ....,..,~H-----+-+-----J---"""""-+-<J 8 ~ ~ 1 \ / \ ,...... SIGNAL GROUNO POWER GROUNO !Al Fig.6: internal schematic of the LM831, as shown in the National Semiconductor Linear Databook, Volume 3. It has a bias circuit which automatically sets the amplifier outputs at close to ½Vee. 114 SILICON CHIP Distortion vs Power Output 10 - ·I i SILICON CHIP BINDERS I ' I , I i r-,...~ I lOkHl 0.5 I 0.2 I I 0.1 -.... 1kHZ ! * High quality up to 14 issues * Hold 80mm internal width * Gold with * SILICONprinted CHIP logo 0.05 ~ BTL MOOE 0.02 1-Vcc•JV. RL•BO C1w•R.1v=0 D.01 0.001 0.0D2 0.005 0.01 0.02 0.05 0.1 POWER OUTPUT (WATT) ' 0.2 0.5 1 Power Dissipation vs Power Output on spine IJ - Vcc•5V ,.... 0.5 ..,.,i., 0.2 ~~ 0.1 0.05 Ycc•6V ~ ~~ - ,f, Ycc~4V Ycca3Y I I ,..~ 1~Holit. THo.:.10% Vcc•2V ,, .,. ,,. 0.02 BTL MODE RL•8U . \~ 1 ~Hl 1 11 D.D1 0.D01 0.D02 0.005 0.01 0.01 0.05 0.1 0.2 0.5 POWER OUTPUT (WA TT) 1 2 S These two graphs show the performance of the LM831 in bridge mode. Good power output is available with only a 3V supply rail. the supply voltage should not exceed 4.5 volts otherwise internal dissipation may become too high. Fig.5 shows an improved bridge mode circuit with larger capacitors to improve the low frequency bandwidth. It also has a 330pF capacitor between the output and noninverting inputs of each amplifier, to curtail the high frequency response. Overall bandwidth is quoted as 20Hz to 20kHz. Fig.6 shows the internal schematic of the LM831 although note that this does not show all the semiconductor details. The input stage of each amplifier is a single transistor rather than the usual differential input stage of most op amps. The DC biasing is arranged so that the output is always at half the supply voltage for supplies above 2 volts. This bias voltage is filtered by the external capacitor between pin 16 and ground. Since the input transistor is a PNP type, no input coupling capacitor is required provided the signal source is referenced to OV. ~ These beautifully made binders protect your copies of SILICON CHIP. In distinctive 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). It will look great on your bookshelf. -------------------~-Yes! Please send me _ _ _ _ SILICON CHIP binder(s) at $A 11 .95 plus $A3 p&p each (NZ p&p $A6). Name _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __ (PLEASE PRINT) Street_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __ _ _ _ _ __ Suburb/town, _ _ _ _ _ _ _ _ _ _ _ _ Postcode_ _ _ _ __ Enclosed is my cheque/money order for $ _ _ _ _ or please debit my □ Bankcard □ Visa Card □ MasterCard I L ~I~~~ l~---'-~~I ~I-'--'--_._____,I l~---'-----'---'I Card No. Signature_ _ _ _ _ _ _ _ _ _ _ _ Card expiry date_~-w w w - -. . . - - - - - - - - - - - .... - -- - - - - - - - - . _ __ ._-----..1 DECEMBER1989 115 ASK SIUCON CHIP Got a technical problem? Can't understand a piece of jargon or some electronic principle? Drop us a line and we'll answer your question. Write to: Ask Silicon Chip, PO Box 139, Collaroy Beach, NSW 2097. Multiple coils for electronic ignition I am interested in building the High Energy Ignition published in the May and June 1988 issues. What I wish to do is make an ignition system using a multiple coil setup similar to the one used on the VN Commodore. This car uses microprocessor controlled ignition but the multi-coil idea could be adapted to normal electronic ignition if I can find a way of alternating the signal from the ignition module from one coil to the other. I intend to use two coils (for a four cylinder car) and I need either an electronic or mechanical solution to the problem. What happens is that one coil fires two spark plugs simultaneously. One is on the firing stroke and the other on a harmless exhaust stroke. I know very little about electronics and was wondering if it would be possible to build a system into the SILICON CHIP ignition High energy ignition does not start I have built the High Energy Ignition project featured in the May 1988 issue of SILICON CHIP and have a problem. The unit is fitted to a Toyota Land cruiser FJ 45 1984 model. When the engine is being cranked over the unit will not fire but immediately the key is released, it will fire. When cranking the voltage drops to about 10.5 volts and I am wondering if the unit is sensitive to low voltage. The unit was built and fitted primarily for a better start. I have replaced the MC3334P IC and the two transistors (BC337 and MJ10012) but the problem still persists. Could you please shed some light on my problem 116 SILICON CHIP module that would alternate the signal between the two coils. If you think it would be possible could I impose on you to do me a diagram and instructions? There are alternatives to alternating the output electronically, so if it is too complicated, don't worry. Your help would be greatly appreciated. (J.K., Ashgrove, Qld). • There are two drawbacks to the system you propose. First, where are you going to obtain the coils which will fire two spark plugs simultaneously? As described in our article on the VN Commodore in the December 1988 issue of SILICON CHIP, this car uses special double ended coils with a high tension output at each end and the coils are integrated with the electronic ignition module. You might be able to obtain these coils as spares but that could be expensive. Second, there is no easy way of switching the output of the high energy ignition from one coil to another. It would be much easier and probably cheaper to simply have two separately controlled ignition modules. Why don't you just try building the Hall Effect ignition as described in our June 1988 issue? It is highly effective and very similar to that used on many four cylinder cars today. Sure, this solution does not get rid of the distributor as would your proposed system but it does have the big advantage that you can do it without too many hassles. Needs a Thorn colour TV circuit Can you help? I need a circuit diagram for a 14-inch colour monitor, model Thorntel PX14TU. I've been all around the traps and have come to a dead end. Any chance that you can assist me? flan Barrow, PO Box 64, Port Melbourne, Vic 3207). • We don't have access to commercial circuit diagrams of monitors. If we did, we could solve a a few problems of our own. Can any reader help? and also give a fix for the unit? (R.K., Darkan, WA). • In our experience, the High Energy Ignition will function well down to quite low voltage. We suspect that you have wired the unit up to one of the fuses coming off the accessory position of the ignition keyswitch. When cranking, power to all accessories is removed which means that your ignition circuit is not powered up during this time. Why are we so sure about this? Because the writer made exactly this same mistake some years ago when installing an electronic ignition system. It did the same thing - nothing while cranking and then it would burst into life as soon as cranking stopped. Optical tachometer doesn't count Could you please help me in regards to your Optical Tachometer [SILICON CHIP, May 1988). After building it, I first set it up to 6000 RPM as per calibration with a fluorescent light. I then put a photostat copy of the strobe pattern on my turntable but no way would it pick up any light or show a glimmer of movement on the meter. Since I wrote the first part of this letter I have tried again to get it working and found that if I put a finger on the circuit board in the area of the Q3 & Q4, I get the needle to FSD and in doing this I was able to set it to 900 RPM using the strobe. The electrolytic capacitors may 6V version of the brake lamp flasher Could you please tell me if the "Flasher Circuit for Auxiliary Brake Lights" featured in the April 1989 issue of SILICON CHIP can be modified for 6V operation? I wish to fit this device to · my 6V motor cycle as a conventional stop light fails to attract enough attention when stopping. If I lower the value of the Darlington transistor and halve the value of the resistors could 6V then drive the unit? Keep up the very good articles and information in your magazine. I'm teaching myself electronics and find your publication very helpful. (G.W., Ocean Shores, NSW). • The circuit itself will work quite happily from 6V without modification but the voltage drop across the BD645, typically about lV, will reduce the brightness of the brake lamp. not all be new but are the ones stated. As the unit works perfectly when tested with a fluorescent light, I am wondering what could be wrong. (R.W., Stuarts Point, NSW). • There is a quick and dirty test to see if the Optical Tachometer is working. Just point it at a light source or open window and then rapidly flick your fingers back and forth in front of the sensor, to simulate a light interrupter. If the circuit is workir..g, the pointer will move part way up the scale. From what you have said with regard to calibration from the fluorescent light source, we think the circuit is probably working correctly. When you are testing from the strobe pattern on the turntable, you need to hold the sensor very close to the platter - within just a few millimetres - otherwise there is too much light reflected from adjacent parts of the pattern. That is probably why you've managed to get the unit going by putting your fingers on the board. By doing this you have altered the r---t>-----<1.--- -YN1r----- -+6V ZD1 15V ,w ~ 6VREIAY I 5A CONTACTS In a 12V system you can live with the slight reduction in brightness but in a 6V system a 1V reduction will mean that the lamp will be too dull. In daylight, you might not be able to see it at all. The only way to overcome this problem is to use a relay to do the switching, as shown in the accompanying circuit. The relay should be fast enough to flash the lamp but if it is not, you may want to reduce the flash rate. This can be done by increasing the 0.15µF capacitor at pin 6 of IC2. The only problem which re- bias on the preamp stage and thereby made it a little more sensitive. However, we don't think the circuit needs modifying to increase its sensitivity. Info wanted on gate turn-off SCRs Do you have any information on the operation, application and availability of gate turn-off SCRs, as referred to by Bryan Maher in the August issue of SILICON CHIP? My reason for asking is that I am interested in building a chopper type speed control for an electric golf buggy. I have seen a commercial speed control which uses two MJl 1016 transistors but it seems to me that a gate turn-off SCR could offer a better solution. (J.E., Bull Creek, WA). • We do have limited information on GTO (gate turn-off) SCRs as made by Philips but no applications circuitry. They are not simple to design into circuitry, for two This circuit will let you adapt the auxiliary brake lamp flasher for 6V operation. It uses a 6V relay to switch the brake lamp instead of a Darlington power transistor. mains is where to get 6V relays. Most kitset and parts suppliers do not stock 6V relays with a contact rating of 5 amps more. You may get one as a motorcycle accessory. Alternatively, you can obtain them from Farnell Electronic Components Ltd, 72 Ferndell Street, Chester Hill, NSW 2162. Phone (02) 645 8888. Their relay Cat 176-696 or 170-191 will do the trick. Alternatively, you could try the Perth branch of Radiospares at 28-30 Northwood Street, West Leederville, 6008. Phone (09) 381 4799. Their 6V 16A relay, Cat 346-025, would be suitable. reasons. First, they have no reverse blocking capability as does a normal SCR and so series diodes need to be added for reverse blocking or parallel diodes added for reverse conduction. Second, the big disadvantage of GTOs is that their turnoff gain is not very high and can be as low as unity. This means that you need a pulse of current, as high as the load current, fed into the gate to turn it off. When first introduced, GTOs were touted as being suitable for high frequency inverters, power supplies and motor control. These days though, these applications seem to have been largely taken over by Mosfets. For really high power applications, such as motor control in rolling mills and locomotives, GTOs are still used although they are very large devices indeed. For lower power motors, high power Mosfets and IGBTs (insulated gate bipolar transistors) have largely taken over. 1§:;l DECEMBER1989 117 Index to Volume 2: Jan-Dec. 1989 Features 01 /89 01 /89 01 /89 01 /89 01 /89 02 /89 02 /89 02/89 03/89 04/89 05/89 05/89 06/89 07 /89 07 /89 08/89 08/89 09/89 09/89 10/89 10/89 11 /89 12/89 4 The Goalkeeper Gatling Gun 6 How To Service Car Cassette Players 18 Marantz LD50 OMS Loudspeakers 40 The Technology Letters , Pt.2 78 Kit Clinic & The UHF Remote Switch 4 Lightning & Electronic Appliances 26 Cutec Z-2000 Stereo Power Amplifier 82 The Technology Letters , Pt.3 84 the Technology Letters, Pt.4 56 Fluke's New 80 Series Multimeters 16 The /PC NEAT/ 40E Computer 76 The Technology Letters, Pt.5 57 Sangean ATS-803A Shortwave Receiver 6 A Day In The Life Of A Computer 10 The Facts On The PhaxSwitch 34 Amcron PSL-2 Preamplifier & PS-400 Stereo Power Amplifier 96 Metrix MX52 5000-Count Multimeter 16 Scopeman Video Microscope 88 The Technology Letters, Pt.6 16 Making Your Electric Radiator Safe 98 The Technology Letters , Pt. 7 90 Simple Program For Resistor Calculations 9 Install A Clock Card In Your Computer Electric Railways 01 /89 02/89 03/89 04/89 05/89 06/89 118 80 Massive Diesel Electrics In The USA 74 The Search For Cost Efficiency 88 NSW XPT Express Passenger Trains 82 The Story Of Amtrak Passenger Services 84 The Burlington Northern Railroad 80 Amtrak's Monster vs. A Swiss Thoroughbred SILICON CHIP 07/89 82 The NSW 86 Class Electrics 08/89 102 The Benefits Of Modern 3-Phase Electric Locos 09/89 102 Swiss Tunnels & Racks 10/89 104 A Look At Australian Monorails 11 /89 92 Pilbara Iron Ore Railways (1) 12/89 82 Pilbara Iron Ore Railways (2) Design & Theory 02/89 03/89 06/89 08/89 12/89 28 Using Comparators To Detect & Measure 42 The NE572 Compandor Chip 4 Understanding Oscilloscope Probes 14 An Introduction To Stepper Motors 112 The LM831 Low Voltage Audio Power Amplifier Vintage Radio 01 /89 1 4 Trou bleshooting The Transformers 02/89 10 Restoring Plastic & Bakelite Cabinets 03/89 16 Timber Cabinets Are A Lot Of Work 04/89 18 Advice To The Budding Collector 05/89 12 How To Date Old Valve Radios 06/89 16 Collecting & Restoring Horn Speakers 07 /89 28 Old Henry - One Of My Favourites 08/89 18 Rebuilding A Vintage Radio Receiver 09/89 12 Valve Portables - Hard On Batteries 10/89 10 Collectables & Non Collectables 11/89 8 The Humble 4-Valve Receiver 12/89 8 Scrounging Bits & Pieces Electronics For Everyone 03/89 04/89 4 What You Need To Know About Resistors 4 What You Need To Know About Capacitors 05/89 4 All About Electrolytic Capacitors 09/89 6 Potentiometers & Trimpots 11/89 76 What You Need To Know About Switches The Way I See It 01 /89 62 Feeling Crook? You May Need An Electron Transfer! 02/89 66 Jump Start Your New Car & Blow Up The Electronics 03/89 74 "Spycatcher": Do Wright's Electronics Bear Scrutiny? 04/89 62 What's Happened To High Definition Television 05/89 44 Are Spikes On The Mains A Hazard To Personal Computers 06/89 24 Back To The Stone Age: Down With Audio, Radio & AC Mains 07/89 78 Police Radar: Where It Works & Where It Doesn't 08/89 90 HDTV: Don't Hold Your Breath 09/89 93 HDTV: Lots Of Problems At The Transmission End 10/89 86 Today They're Tagging Animals; Tomorrow It Might Be Humans! 11/89 86 Electronic Identification: A Boon Or A Catastrophe 12/89 98 Broadcast Television: An Industry That's Not Sure Where It's Going! TETIA TV Tips 01/89 57 Hitachi CEP288 02/89 58 National CP2000 03/89 61 AWA-Thorn N Chassis; GEC 2213-A; Sanyo CTP5601 04/89 75 Philips K9A 05/89- 37 Philips KT2A-3 06/89 38 Kriesler 59-03 07 /89 55 Hitachi PA3-A Chassis 08/89 62 Philips K9 09/89 43 Sanyo CTP6631 (80P Chassis) 10/89 53 Sony KV1300AS; AWA-Thorn VCR ATV4 11 /89 49 National TC2202 (M8 Chassis) 12/89 39 AWA C6319 (Q Chassis); Alpine AL51 Cassette Deck Projects To Build 01 /89 26 Ultrasonic Proximity Detector For Cars 01 /89 32 A Line Filter For Your Computer 01 /8 9 44 120W PA Amplifier , Pt.2 01 /89 68 Simple Computer Sound Repeater 02/89 20 Transistor Beta Tester 02/89 37 Minstrel 2-30 Loudspeaker System 02/89 52 LED Flasher For Model Railways 03/8 9 26 Stereo Compressor For CD Players 03/89 34 LED Message Board, Pt. 1 03/89 44 32-Band Equaliser, Pt.1 03/89 64 Map Reader For Trip Calculations 04/89 22 Telephone Bell/Monitor Transmitter 04/89 30 Flasher Circuit For Auxiliary Brake Lights 04/89 36 LED Message Board, Pt.2 04/89 46 32-Band Equaliser, Pt.2 Serviceman's Log 01 /89 02 /8 9 03/89 04/89 54 58 56 70 05/89 32 06/89 34 07/89 52 08/89 62 09/89 40 10/89 50 11/89 48 12/89 34 Copping It Right In The Neck A Sharp In Pye Clothing The Line Of Most Resistance When VCR Means Very Crook Recorder Brand What? Never Heard Of It! Look Before You Leap You Need A Pal To Deal With PAL Toss Yer - Triple Or Quits It's A Long Way To Trip A " Rarery" "Bar Humbug" - As Scrooge Would Say You've Got To Be Sharp In This Game Knowing When To Draw A Line Computer Bits 07/89 70 A Look At Video Monitors 08/89 82 Display Adapters - From Monochrome To Thunderdome 09/89 75 A Guide To Hard Disc Drives 10/89 76 Installing A Hard Disc In The P~ 11 /89 68 Floppy Disc Drives: Formats & Options 12/89 70 Adding RAM To Your Computer Remote Control 4 The Beginnings Of Remote Control 11 /89 40 Modern Radio Control Systems 12/89 112 Operating An R/C Transmitter 10/89 Circuit Notebook 01 /89 01/89 01 /89 02/89 02/89 38 38 39 44 45 Pulse Charger For Dry Cells 200-250mA DC Electronic Fuse RS232 to RS422 Adaptor Simple Binary Encoded Keypad Crystal Oscillator Using A CMOS 555 05/89 05/89 05/89 05/89 06/89 20 38 48 62 10 06/89 06/89 06/89 07 /89 07/89 48 60 70 14 32 07/89 42 07/89 58 08/89 6 08/89 26 08/89 08/89 09/89 09/89 09/89 48 76 20 27 52 A Synthesised Tom-Tom Biofeedback Monitor For PCs Electronic Pools/Lotto Selector LED Message Board, Pt.3 Passive Loop Antenna For AM Radios Build The Touch-Lamp Dimmer Universal Temperature Controller LED Message Board, Pt.4 Exhaust Gas Monitor For Cars Extension For The Touch-Lamp Dimmer Experimental Mains Hum Sniffers Compact Ultrasonic Car Burglar Alarm Build An AT Tower Computer Studio Series 20-Band Stereo Equaliser, Pt. 1 Build The Garbage Reminder Low-Capacitance Scope Probe 2-Chip Portable AM Stereo Radio Alarm-Triggered Telephone Dialler High Or Low Level Fluid Detector 02/89 45 Alternative Override For Car Safety Light 03/89 32 Photo-Interrupter For Digital Counter 03/89 32 Schmitt Trigger Using Discrete Transistors 03/89 33 Wide Bandwidth Video Amplifier 03/89 33 High Impedance 1-Watt Amplifier 04/89 80 Keyboard Sound Improver 04/89 81 Keypad Alarm For Car Security 04/89 81 Relay Output For Door Minder 05/89 26 Leading Zero Blanking For Digital Speedos 05/89 27 Thermostat For Cooling Fans 05/89 27 Bit Saver For Soldering Irons 06/89 32 Power Supply For Walkman Radios 06/89 32 X-Y Light Source Plotter 07 /89 22 Tone Decoder Input Control Circuit 07 /89 22 Using Centre-Zero Meters In Power Supplies 07 /89 23 Low Cost Locker Alarm 08/89 46 Channel Switch For DSE UHF Converter 08/89 46 Flasher Unit For Cars 08/89 47 Fuse-Fail Alarm For Cars 08/89 47 Car Battery Voltage Monitor 09/89 58 Sawtooth/Triangle Waveform Generator 09/89 58 Digitally Controlled Stereo Volume Control 10/89 7 4 Siren & Flash Generator For Toy Cars 10/89 7 4 Balanced Outputs From A Single Supply 10/89 75 Timer For Motor Driven Cameras 11 /89 61 Walkman Car Stereo Amplifier 11/89 62 Traffic Light System For Model Railways 11/89 62 4-Channel Mixer With Effects Send 12/89 21 High Current Intelligent Charger ,12/89 21 Exhaust Temperature Alarm For Boats 12/89 22 Self Cycle Bilge Pump Control 12/89 22 El Cheapo Buffer Amplifier 09/89 60 Studio Series 20-Band Stereo Equaliser, Pt.2 09/89 80 Offset Nulling Circuit For Power Amplifiers 10/89 20 FM Radio Intercom For Motorbikes 10/89 32 The Gladesville GaAsFet Amplifier 10/89 40 1-Megabyte Printer Buffer 10/89 58 2-Chip Portable AM Stereo Radio, Pt.1 11 /89 4 Build A low-Cost Analog Multimeter 11/89 14 Super Sensitive FM Bug 11 /89 18 The Radfax Decoder 11 /89 32 2-Chip Portable AM Stereo Radio, Pt.2 11 /89 64 FM Radio Intercom For Motorbikes 12/89 24 Digital Voice Recorder Board 12/89 46 Easy To Build UHF Remote Switch 12/89 74 Balanced Input/Output Stages For The Studio Series Equalisers 12/89 23 Stereo FM Microphone Transmitter Amateur Radio 01 /89 71 Relative Signal Strength Indicator 02/89 50 Build A Simple VHF FM Monitor Receiver, Pt.1 03/89 68 Build A Simple VHF FM Monitor Receiver, Pt. 2 04/89 42 The Dick Smith Satellite Receiver 05/89 69 Simple Stub Filter For TV Interference 06/89 66 Coherent CW - A New Low Power Transmission Technique 07/89 66 Intelligent Charger For 1 2V Gel Batteries 08/89 66 GaAsFet Preamplifier For The 2-Metre Band 09/89 72 Simple DTMF Encoder For Custom Control Circuits 10/89 84 SWR - Just How Important Is It? 11 /89 46 Two-Tone Test Oscillator For SSS Transmitters 12/89 92 Simple HF Receiver For The 40-Metre Band Notes & Errata 01 /89 02/89 03/89 03/89 04/89 05/89 94 94 95 95 94 94 06/89 94 09/89 111 09/89 111 09/89 111 10/89 111 10/89 111 10/89 111 10/89 111 Poor Man's Plasma Display Fish Bite Detector Hands-Free Speakerphone Ultrasonic Proximity Detector 1 20W Public Address Amplifier Stereo Compressor For CD Players Pools/Lotto Selector Studio 200 Stereo Control Unit Narrowband VHF FM Receiver Extension For The Touch Lamp Dimmer Touch Lamp Dimmer Studio Series 32-Band Octave Equaliser Ultrasonic Car Burglar Alarm Garbage Reminder DECEMBER 1989 119 CEN Cash in your surplus gear. Advertise it here in Silicon Chip. CLASSIFIED ADVERTISING COUPON Advertising rates for this page: Classified ads - $7 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. Print your advert on a separate sheet of paper and send it with this form and your payment to Silicon Chip Classifieds, PO Box 139, Collaroy Beach, NSW 2097. Fax: 982 9553. Name .. Street Postcode Suburb/Town or please debit my Enclosed is my cheque or money order for $ O Visa Card O MasterCard 0 Bankcard I Card No \ I .. Card expiry date ..... ../. ...... / .. . Signature FOR SALE PUBLIC DOMAIN & shareware software for IBM & compatibles. Catalog disc $4.00. Also TV-REPAIR.TXT which covers faults in most popular brands. It can save hours of work. On a 5¼-inch disc. Just $28.00 inc. p/post. Martins Television Service, PO Box 1013, Taree, NSW 2430 . BUILD YOUR OWN LED Moving Message Board. This 16-character $150 short form kit was featured in MEMORY CHIPS Prices at November 6, 1989 Speed 150ns 120ns Chip Type 10Dns SIMMS 9 x 256 9 x 1 mb 9 x 1mb 9 x 1mb 9 x 1mb 8 x 1 mb 8 x 1 mb SIPP$ 9 x 256 9 X 1mb DIP 411000 44256 41256 4464 4164 Sales Tax: 20% HP LP HP IBM LP IBM HP LP - 50.00 - 55.00 60.00 155.00 180.00 210.00 185.00 210.00 250.00 150.00 170.00 190.00 50.00 60.00 65.00 185.00 215.00 3.50 3.75 2.30 2.50 Overnight Delivery 16 .20 17.00 4.60 5.00 2.80 Tel (02) 427 0011 Fax (02) 428 5460 SILICON CH'P - ACTIVE TRANSMISSION line stereo speakers. Includes preamp. $760.00 . Send SAE to 36 Palmer St, Nambucca Heads, NSW 2448. BUILD A COMPUTER CONTROLLED micro robot with step by step instructions on how to make the electronic interface to connect the robot to a computer. A computer program is also included . Send cheque or money order. for $9.95 to L.R. Barnett, PO Box 187, St Lucia University, Qld 4067. - 16.50 17.40 5.00 5.50 5.20 - Credit Cards Welcome PELHAM 120 80ns 70ns Prices Excluding Tax SILICON CHIP from March to June 1989. Kit consists of PC boards, EPROM and full instructions to complete the project to a professional standard . Loaded from Centronics printer port or PC/XT keyboard . Equivalent commercial units start at around $1 000. For more information , send a 41 c stamp to Don McKenzie, 29 Ellesmere Crescent , Tullamarine 3043. SATFAX: WEATHER SATELLITE picture receiving program for IBM XT/AT. Displays in 64 colours. Needs EGA colour monitor & card, AM demodulator & ADC interface. $45 plus $3 postage . RADFAX2: HF WEATHER FAX, Morse & RTTY receiving program for IBM XT/AT. Needs CGA, SSB HF, FSK/tone decoder. Also "RF2HERC " & "RF2EGA", same as RADFAX2 but Advertising Index Acel Electronics 97 Allied Capacitors 99 Altronics 88-91 Sambor Electronics . 75 Banksia Information Tech . 1 ·1 Board Solutions . IBC Dauner Electronics 73 David Reid Electronics . 13 Dick Smith Electronics 40-45 Electronic Solutions 32,33 Elmeasco . . . . . . . . . . . . OBC Energy Control . 73 Geoff Wood Electronics .... IFC Harbuch Electronics . . . . . . 38 Hycal Instruments ........ 75 Jaycar Electronics 1 7-20 101-104 J.V. Tuners 38 Pacific Microelectronics 108 PC Marketplace 53-68 Pelham . . .. 120 RCS Radio. 100 Rod Irving Electronics 110,111 Tandy Electronics 3,5 suitable for Hercules & EGA cards respectively . $35 plus $3 postage. All programs are on 5.25-inch 360K floppy disc & include full documentation. Only from M. Delahunty, 42 Villiers St, New Farm, Qld 4005. Phone (07) 358 2785. THE HOMEBUILT DYNAMO by Alfred T. Forbes. Published by Todd-Forbes Publishing, Oratia, Auckland, New Zealand . Hard cover, 8½ x 12 inches, 182 pages with over 300 illustrations. ISBN 0-95977 49-0-4. Price $A85 postpaid airmail direct from ToddForbes Publishing, Dept. 03, PO Box 3919, Auckland, New Zealand. Trade enquiries invited . "What a delight this book will be to any lover of anything to do with DIY, ingenuity and devotion to the completion of a job once started. It is the complete pictorial history of how Alfred Forbes built a dynamo to power his house in New Zealand ... Definitely a book to put on your list of wanted Christmas presents". - Practical Electronics. Package 1 You get: Package 2 This provides all 51/4'' disc formats, with both a high and a low density drive 1: An all-standard floppy drive adaptor A superb EGA monitor and EGA graphics card at a massive saving. 1: A 14" EGA Monitor The ACMEGA is a full EGA colour monitor, providing both text and graphics display with all EGA andCGAcompatible graphics cards. It features a 0.31 mm dot pitch tube with anti-reflective coating. A tilt and swivel stand is provided. You get: The adaptor is fully compatible with the IBM PC/XT, PC/AT and compatibles and allows connection of all types of both 51/4" and 3½" drives. l or 2 floppy drives can be connected Any combination of 1.2MB and 360KB (5.25") or 720KB and 1.44 (3.5') drives may be connected. DOS compatibility: Version 3.0 or later. Cable is supplied with connectors for both 5.25' and 3.5' drives. Note: DOS Version 3.3 or later is required for 1.44MB 3112" drives. Normally $699.00 2: An EGA Card with monochrome mode NORMALLY $99.00 2: A 360K 5.25 inch floppy drive ,~ Superb Japanese quality drive. Standard double sided/double density, featuring brushless DC motor design. \ i_ This enhanced graphics adaptor is designed to upgrade the graphics display of the IBM PC/XT, AT and compatibles to a high resolution display. Compatible with the complete expanded IBM Enhanced Graphics Adaptor and providing 256KB standard video memory, it is also fully compatible with the IBM Monochrome Display Adaptor (MDA) , Hercules Graphics Adaptor (HGA), and Colour Graphics Adaptor (CGA) Normally $249.00 NORMALLY $175.00 3: A 1.2MB/360K 5.25 inch floppy drive Superb Japanese drive. This dual standard high/low density drive features a brushless DC motor for high reliability . Head positioning via a steel band and stepper motor for high accuracy. NORMALLY $199.00 Normal total price . .......... $473 Buy all three and pay only .... $399 SAVE ................. . ..... $74 MAJOR AUTHORISED STOCKISTS Albany Broken Hill Bunbury Charlestown Coffs Harbour Deniliquin Devonport Glen Innes lnverell Leeton Lightning Ridge Lismore Mackay Maryborough Morwell Mount Gambler Mt Isa Mudgee Nambour Narrabri Port Lincoln Taree WaggaWagga Warnambool Windsor Micro Electronics Hobbies And Electronics Micro Electronics Newtronics Coffs Harbour Electronics Deni Electronics A 1 Electronics John Summerlad Electronics Electronic Systems Leeton Audiotronics Cycle & Sound Decro Electronics Steven's Electronics Keller Electronics Morwell Electronics Hutchesson's Communications Outback Electronics Headware Nambour Electronics Namoi Computers Bassham's TV & Computer Brad's Electronics Phillip's Electronics Maartronics M&E Electronic Communication 412077 884908 216 222 439 600 525 684 813 672 248 322 323 661 221 821 532 081 290 579 214137 511 723 214 559 346133 250 400 433475 r!'lr::l"IW::r':'1~ 723 895 411604 .....,i.:::,,:..o,:,f..l 923 274 822 788 , 526 603 216 558 629 870 775 935 Normally these would cost you . $948 Buy both for only . . .$899 SAVE . . . . . . . . . . . . .$49 FREE WORDMAGIC WORDPROCESSING PACKAGE WITH ANY PURCHASE OVER $7501 This powerful yet easy to use wordprocessor is for people who don't want to learn to be computer experts, they just want to get words down on paper! And it's yours FREE with any purchase over S750! Complete with easy-to-follow manual and command card. Features: Full WYSIWYG , Simple mnemonic commands, Automatic save to disk, Typewriter mode, instant word count, upper / lower case conversion. VALUE $140.00 Board Solutions PTY. LTD. P.O. BOX 1120 LANE COVE 2066. TELEPHONE 906 5696 FAX 906 5222 Special prices available until 30th December 1989 • 14 day money-back guarantee (except software) • 3 month warranty on all products • Mail orders our speciality • Freight on small items is $9.00 Insurance (if required) $1.00 per $1 00 of order value • All prices include sales tax • We accept Bankcard, Mastercard & Visa • Call for our latest price list