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BUILDING THE DIGITAL FUNCTION GENERATOR * Horace 1he Electronic Cricket * Universal Timar For Appliances HS-3000 Plus HANDY SCANNER "THE TOTAL SCANNER SOLUTION" GOODWILL GOS-622 20MHz 2CH. OSCILLOSCOPE * Display: CH1 , CH2, DUAL, CH1, CH2, X-Y. * Sweep Modes: Auto, Normal, Single Shot. For uses with: DESKTOP PUBLISHING WORD PROCESSING CAD APPLICATIONS DATA BASE WIDE 4.13" (105mm) SCAN WIDTH 1 00/200/300/400 SWITCHABLE DPI RESOLUTION WAS $499.00 NOW ONLY * Auto Trigger Level Lock , Variable Hold-Off. * Sensitivity: 5mV/DIV to 5V/DIV to 20MHz. * INCLUDES 2 x 1:1 10:1 PROBES * ONLY * $799.oo 12 MONTHS WARRANTY $385 1600 WATT HEATGUN PORTASOL "PRO" GAS SOLDERING IRON KIT Two heat settings: 400°C/600°C. Great for heatshrink tubing, paint stripping, or bending PVC pipes. Designed for the craftsman ,. technician, or professionals requiring micro-precision soldering with adjustable power equivalent to 60 watts. Complete kit includes Portasol tool, 4 tips (Soldering iron, Blow Torch, Hot Blower, Hot Knife) , safety stand, cleaning sponge and handy storage case. AALEC ONLY $55.oo RECHARGEABLE ~~;;;;;;;;J=r:~to=-> \it;! "DRILL 'N' DRIVE" NOW Two speed cordless Drill and Screwdriver. $59.95 HDS-90L PROBE TYPE DIGITAL MULTIMETER EMTEK UPS-501 UNINTERRUPTIBLE POWER SUPPLY 500 WA TT The UPS provides instant emergency inverter power in the case of mains distubances or failure. PLA YMASTER "PRO SERIES ONE" HIGH POWER AMPLIFIER KIT NORMALLY $599.00 NOW * $549.oo Output power: 140W RMS into Bohm. 200W RMS into 4 ohm. Distortion: 0.005% at 1DOW into 8 ohm. Frequency response: 1OHz to 1OOkHz. VIDEO TRANSMITTER Ideal for watching a video in the bedroom, kitchen etc. without having to move your complete VCR system or having long extension cables running from one end of the house to the other. * Output channel: UHF 30 * Transmitting distance: 1Omtr. * Complete with power supply and connecting cables. ONLY * $89.95 127 YORK STREET SYDNEY 2000 PH: (02) 267 1385 BUSINESS HOURS: Mon-Fri 8:30 to 5:30, Thurs 8:30 to 7:00, Sat 9:00 to 1 :00 COMPUTER DISKETTES a COAXIAL CABLE CONNECTOR CRIMPING TOOL 5.25" D.S.D.D. $6.45 PKT 10 $60.00 BOX 100 * This handy crimper has five different sized crimping jaws to suit most BNC, F, Mini M, M, N, and TNC coaxial connectors. Insulated handles with spring return. Push to release button. Jaw sizes: 1.72, 2.5mm. * Jaw sizes: 5.4, 6.48, 8.2mm . 5.25 11 D.S.H.D. 1.2mb . ....... $14.95 PKT 1 0 3.5" D.S.D.D. $16.50 PKT 10 $120.00 BOX 100 3.5 11 D.S.H.D. 1.4mb * * * .. $33.00 PKT 1 0 ONLY MULTIFUNCTION CAR ALARM with WIRELESS REMOTE PHOTO ELECTRIC SMOKE DETECTOR Designed to be used as a stand alone unit or in conjunction with an alarm or security system. . '* Does not use radioactive substances l and is triggered by visible smoke itself rather than heat. 9 volt battery operated. Wireless remote active/deactive alarm system and central door locking system (where fitted). Horn sounds to confirm armed. Lights flash to indicate disarmed. * ONLY NOW ONLY $129.oo $59.95 Convert your Oscilloscope to a Spectrum Monitor with a Bandwidth of 100MHz C-400 WITTY MOUSE ~ ;.:_, ''¾, . c:::::::;;;;;;, - i--- / ' , * Optical rotary encoder. * Max. tracking speed: 200mm/sec. * Resolution: 195 dots/inch. . * Mouse driver software inc luded. * IBM XT/AT compatible. $69.95 * The SPECTRUM PROBE is a low cost 100MHz Spectrum Analyzer in a handheld probe. Now see the frequency components of signals and noise. Use it as a sensitive RF detector. Locate radiated EMI sources. Check your RF signal generator. Check for stage gains in amplifiers. * PRICE TO CLEAR NOW ONLY * $49.95 * * * $395 Great value for only FOAM EAR PADS TO SUIT SENNHEISER HEADPHONES THREE WAY AUDIO/VIDEO STEREO SWITCHING BOX Replacement foam earpads to suit SENNHEISER outer ear stereo headphones. Selects oetween three stereo audio/video inputs to one stereo audio/ video output. Can also be used as a stereo audio only selector as well. All sockets are standard RCA. .Complete with 3xRCA to 3xRCA lead. * * Yellow in colour * ONLY $5.95/2 pairs per set TWO WAY SPEAKER SELECTOR SWITCH Select between two sets of stereo speakers, switching from one to the other or selecting both at the same time. * Easy screw terminal inputs. 240 VOLT 120mm FAN NOW ONLY $16.95 600 WA TT INVERT Air Flow: 80 CFM AVAILABLE IN KIT OR BUILT-UP VERSION NOW ONLY $16.95 SAVE $12.00 12 VOLT 80mm FAN Air Flow: 30 CFM (approx.) NOW ONLY $14.95 MAIL ORDERS: P.O. BOX 0103, PHONE ORDERS: (02} 267 1385 FAX: (02) 261 8905 At these prices it will BLOW you away SYDNEY 200.0 ~ I- V1S4 ~ .. I! I 1---. lDl · I-A' -=•m A This inverter has the capability to produce 600 watts of mains power from a 12 volt car battery. $499/Built $399/Kit <at>>_ D,,,mC/ub lmernauonaf POST & PACKING $5 - $25 · · · $3.00 $26 $50 $5 00 - ·· · $51-$100 $1 01 $499 · $6.00 $8 00 ·· · $500 + FREE ~ ;J i-1 ;.....ll :::J lj --- --g :::::::J j..J fit:1 ...J ~ __, ;; I t_ H '-" AUGUST 1990 THIS NEW UHF TRANSMITTER uses a SAW filter so you don't have to make frequency adjustments. Details page 16. FEATURES 32 The Story Of Electrical Energy, Pt.2 by Bryan Maher The quest for greater efficiency 76 Laservision: High Power Communication by L. Simpson Mixing technology with advertising 82 The "Tube" vs. The Microchip by Garry Cratt We compare a vintage shortwave receiver with it modern counterpart PROJECTS TO BUILD 16 High-Stability UHF Remote Transmitter by Greg Swain For DSE & SILICON CHIP remote switch circuits 20 Universal Safety Timer For Appliances by John Clarke Turns off the power after 9 minutes 52 Digital Sine/Square Wave Generator by John Clarke Pt.2: the construction details 66 Horace The Electronic Cricket by John Clarke He's fully house trained & under your command SPECIAL COLUMNS 6 Vintage Radio by John THE "TUBE" VS. the microchip: in the left corner the Collins 51]4 general coverage receiver from the 1950s; in the right the Yaesu FRG-7700. Who won? - see page 82. THE SERVICEMAN tried everything this month (pity the poor cat). So why (Grrr!) wouldn't the picture cooperate by staying on? Turn to page 46. Hill Tuned radio frequency receivers 46 Serviceman's Log by the TV Serviceman It was the last thing I tried 70 Computer Bits by Jennifer Bonnitcha What to do when your computer goes bung; Pt.4 88 Remote Control by Bob Young Bluff body design & automotive aerodynamics DEPARTMENTS 3 Publisher's Letter 4 Mailbag 42 Circuit Notebook 96 Product Showcase 104 Back Issues 2 SILICON CHIP 106 Ask Silicon Chip 108 Notes & Errata 109 Subscription Page 110 Market Centre THIS PROJECT WILL automatically switch off an electrical appliance after 9 minutes unless a reset button is pressed. See page 20. PUBLISHER'S LETTER 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) 979 5644 Mobile: 018 28 5532 Victorian Representative McDonald Woodside & Associates Pty Ltd, 143a Como Parade East, Parkdale, Victoria 3194. Phone (03) 587 5155. Contact: Cameron McDonald . On mechanical & acoustic filters Ever looked at one of those fancy new communications receivers and marvelled at how much performance is crammed into their small cases? They are jewels of miniaturisation with more features than any one person is ever likely to use: scanning, lots of memory for storing wanted stations, comprehensive coverage, multiple modes. You name it, you can have it, provided you are prepared to pay the price. But have you ever wondered just how much better these modern communications receivers are compared with the best that was on offer 30 or 40 years ago? That is one of our stories this month. The conclusions will surprise you. Essentially, while great strides have been made in making communications equipment smaller, more reliable and crammed with operating conveniences, today's manufacturers haven't really managed to make them receive signals any better. To me, the really interesting aspect of those old communications receivers was their use of mechanical filters to give unsurpassed selectivity. Typically, they worked at 455kHz or at 500kHz. Now how could this be? How could anything mechanical work at 500kHz? I'm not going to give away the whole story here - you can read it yourself, beginning on page 82. But while the concept of anything mechanical working at 500kHz may seem staggering, one of our projects this month uses a surface acoustic wave filter which works at over 300MHz. How's that again? An acoustic device working at 300MHz? Impossible! Not so. Surface acoustic wave filters, SAW filters for short, have been widely used in TV and communications equipment for quite a few years now although it is only just recently that they got into the realms of 300MHz. They are a resonant device which works by propagating an acoustic wave across a piezoelectric crystal. Often, when designers are trying to model physical systems, such as loudspeaker systems for example, they use electrical analogs or equivalents. This helps them understand the system better and therefore ultimately leads to better performance. However, the use of mechanical filters and SAW filters shows that it is possible to go the other way and get results which are almost unthinkable. Isn't it true that, the more you read about electronics, the more fascinating it becomes? Now have a look at that article comparing two communications receivers on page 82. Those designers of 40 years ago certainly knew what they were about. Leo Simpson Regular Contributors Jennifer Bonnitcha, B.A. Garry Cratt, VK2YBX John Hill Jim Lawler , MTETIA Bryan Maher, M.E., B.Sc. Jim Yalden, VK2YGY Darren Yates Bob Young Photography Glen Cameron 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. Typesetting: Magazine Printers Pty Ltd , Rozelle, NSW 2039. Printing: Macquarie Print, Dubbo, NSW 2830. Distribution: Network Distribution Company. Subscription rates: $42 per year in Australia. For overseas rates, refer to the subscription page in this issue. Liability: Devices or circuits described in SILICON CHIP may be covered by patents. SILICON CHIP disclaims any liability for the infringement of such patents by the manufacturing or selling of any such equipment. Editorial & advertising offices: Unit 39, 5 Ponderosa Pde, Warriewood , NSW 2102. Postal address: PO Box 139 , Collaroy Beach, NSW 2097. Phone (02) 979 5644. Fax (02) 979 6503 . ISSN 1030-2662 AUGUST 1990 3 MAILBAG Microwave cooking destroys good food I heartily concede your superior expertise in electronics but not necessarily in nutrition. There you are probably way out of your depth. Your editorial in the April issue might lull some unsuspecting people into believing the fallacious notion that microwave cookery is safe and beneficial. I spent 60 years of my life studying, teaching and advising on nutrition. I have not found any scientifically acceptable evidence to show that microwave cookery is safe or desirable. Furthermore, there is not one iota of evidence to show that cooking of any kind improves the nutritional value or safety of food. Microwave cookery is simply a faster but more expensive way of destroying good food. Kenneth S. Jaffrey Nelly Bay, Qld Speed control in model aircraft I would like to reply to the points raised by George Lindley in Mailbag in the July issue of SILICON CHIP. The questions raised on using the elevator as a speed control is a very subtle one but is bound up essentially in the difference between full size and model aviation. In the modern, neutrally stable, zero centreline aerobatic model, the requirements demand that the aircraft can be flown throttle on throttle off without any trim change whatsover. If there is the slightest deviation from straight and level, then the design, rigging or trimming is incorrect and needs urgent attention. It is not until kinetic energy and thus airspeed has been washed off that this type of aircraft will begin to descend in the glide. This is only possible in aircraft with symmetrical wing sections and very light wing loadings. In fact, they fly more like ballistic missiles than aircraft. In this situation, the throttle is very much the speed control. Up and down must be accomplished with the elevator control. The position in a heavily loaded 4 SILICON CHIP full-size aircraft is infinitely more complex. These aircraft usually use an asymmetrical wing section rigged at a positive angle of attack. This rigging is so arranged that the Cd of the fuselage is at a minimum at the angle of attack that gives the best lift/drag ratio on the wing. Thus, the action of the elevator now becomes extremely complex but essentially the task of the pilot is to fly his aircraft at the most efficient speed. He does this by setting the throttle to economical cruise and adjusting the speed with the elevator to give the speed which corresponds to the best lift/drag angle. So you see Mr Lindley, we were both correct. It just depends on your point of view: designer or pilot; model or full size. The problem arises from trying to write a single article to cover both situations. Finally, with regard to stalls, I should of course said that they can be dangerous. However, the inference of the original article was that the stall could occur at an awkward moment. Bob Young Silvertone Electronics Modifying the Studio 200 power amps I am writing in response to A.K.'s letter in the June Mailbag. I realise that a lot of space has been given over to this particular topic but I feel there are still important things to say and, as I have previously mentioned, I like the opportunity for a good technical discussion. I shall deal with A.K. 's letter point by point. In his first point, A.K. gives his reasons for including emitter resistors in the first stage, and these are quite good reasons except that he misses another very important point. Can the modified amp still keep distortion low with this drastic cut in gain? I feel that the most important sources of distortion will be the second and third stages because they have to operate over much larger voltages and currents - not the first stage. If the first stage gain and therefore the total open loop gain is reduced then the amp's ability to SILICON CHIP, PO Box 139, Collaroy Beach 2097. reduce distortion through feedback is similarly reduced. I get the impression from the last sentence of A.K. 's first point that he does not fully comprehend the mechanism and the usefulness of feedback. He is using more "local" feedback and reducing "overall" feedback. In his second point, A.K. says "Further audible improvement was noted .. .'' and I will address this particular method of assessment later. I was prompted to go back over all that was printed on this topic and I looked particularly at the second stage of the amp. In A.K. 's modified design, Q4 has no collector load except for its own output impedance in parallel with the output impedance of Q14. Because of this, Q4 will have very high gain and will be prone to saturation and clipping. A.K.'s biasing scheme can do nothing for this. If Q4 clips asymmetrically, then the feedback circuit comprising Q14, Q15 and Ql could conceivably cause an imbalance in the collector currents in Q2 & Q3. Also if Q4 does saturate, it will generate distortion which will be coupled through its emitter to Q5. I would not be in the least surprised to find that fitting separate emitter resistors will improve this situation because fitting separate resistors will decouple Q4 from Q5, thus preventing any distortion coupling from Q4 to Q5 and resulting in "further audible improvement". Fitting separate emitter resistors also reduces the gain of this stage and hence the overall gain by about 10 or 20 times (pretty drastic!) and will probably increase the distortion produced by this stage. In point three, A.K. talks about thermally coupling Q6 and Q14 and about "VBE tracking (matching)", I think A.K. is confusing two separate issues here. Sure, this will produce some :VBE tracking but this is quite different to matching. In my first letter I said that A.K. should match for VBE not for hpE, which means he should select his transistors for pairs that have the same VBE at the particular operating conditions. Thermal coupling for VBE tracking is recommended for all differential pairs. In point four, A.K. claims that "The Problems? main reason for Q15 is to slightly reduce the voltage drop across LED 1 as the hpE of Q4 and Q5 increases during warm-up thereby keeping the Q2 and Q3 collector voltages within less than 5mV of each other' '. I think that this is a poor description of the circuit's operation. First, it is highly unlikely that shifts in the hpE's of Q4 and Q5 will have an important effect; certainly not compared to the effects that their VBE's will have. Second, if Q15 and the associated feedback network were removed, gross DC imbalances could easily occur that would render the amp quite unstable, at DC at least. I feel that the original design would have delivered stable and predictable performance with fewer components and would have provided a fair measure of temperature compensation for gain and hence stability. Finally, I am a little disturbed at A.K.'s insistence on balancing collector voltages when this is not a very important parameter and does little to describe the performance of the amp as a whole. VBE tracking and the matching of collector current are far more indicative of circuit operation and performance. And now to A.K.'s method of evaluation. I think for a nyone who seriously wants to get some handle on the performance of any audio equipment, "audible improvement" is simply inadequate. To evaluate any audio equipment by ear with an end to identifying any real differences, the following points must be observed: (1). you must have a reference component (another Series 200 amplifier in this case); (2). you must have the gains in both components matched to less than ldB, which should be done with a meter and an oscillator (not too common in hifi stores) because the human ear is just not good enough; (3). it must be done in identical acoustic environments, including position of equipment, number and position of people etc in the room; (3). it should be done by switching quickly between the component under test and the reference component; and (4). it must be done with the individuals making the assessment completely unaware of which component they are testing. On this basis, A.K.'s claims for his modified amplifier are pretty worthless without some objective testing to support his claims. A.K.'s claims may have some real basis in fact (although I am sceptical) but without some objective testing and/or some rigorously controlled listening tests, we just cannot tell. My gripe is that his mods have poor justification on an engineering/design basis and his "tests" tell us nothing much except that he thought the modifications improved the sound. One area that has not been covered at all is the subject of frequency compensation and its effects on frequency response, slew rate and stability. As A.K. has drastically altered the open loop gain of the amplifier, so will he also alter the gain bandwidth product. This could adversely affect the closed loop bandwidth. Since most of A.K.'s modifications would seem to reduce the gain of the amplifier I guess it would probably not cause instability but it may reduce the bandwidth to something less than desirable. This is mostly speculation; I bring it up only because it is a very important part of amplifier design that has not yet been considered in this debate. To finish, I would like to repeat what I said in my first letter: that A.K. is to be encouraged, although there is not much encouragement in what I have said. His cause is holy I feel that making the amplifier more linear with less need for overall feedback is a good thing to do. I just think he is going in the wrong direction. I think A.K. should go back to a fully differential second stage and he should perhaps explore the nonlinear behaviour of the output stage and its effects. And I feel he should rethink his biasing circuit for the first stage. The references I gave in my first letter are a goldmine of hard to find information on this topic and there are many other useful sources as well. Phil Denniss Chippendale, NSW ... and you don't have our NEW 1990/91 148 p§lge electronic parts and accessories catalogue ... Its our latest TRADE catalogue for the consumer ARISTA ... Your one-stop problem solver. ... Stylus ... ...Plugs, Jacks and Sockets ... ... Batteries ... ... Cable ... ... Tools and Technical Aids ... ... Plug and Power Packs ... .. .Car/Auto Accessories .. . ... Boxed Hi Fi Speakers .. . ... Raw Replacement Speakers ... ... Speaker Accessories ... ...Telephones and Intercom .. . ... Public Address Accessories .. . ... Security and Alarm Accessories .. . .. .TV/Video/Antenna Accesories .. . ...Videocam Accessories ... ... Audio Accessories ... ... Headphones .. . .. .Computer Accessories ... ... Microphone Accessories ... ... Mixers, Amplifiers, Equalizers ... Just about anything you want. .. Get your catalogue complete with "Recommended Retail Prices" free from your local ARISTA dealer or send $2.50 P & H and your return address to: ARIST~ ELECTRONICS PTY LTD PO BOX 191. LIDCOMBE, NSW, 2141 AUGUST 1990 5 VINTAGE RADIO By JOHN HILL • Tuned radio frequency receivers Because of their basic simplicity, TRF receivers are usually fairly easy to restore. These receivers are usually worth collecting although their performance is not up to superhet standards. TRF [tuned radio frequency) receivers were popular during the early years of radio, particularly in the first decade of broadcasting. In the 1920s, they took the form of multi-dial sets with two or three tuning dials, while in the early 1930s they had the more conventional single knob tuning of that era. These latter types look a bit like early superhets but a close examination soon reveals that they are not. The TRF receiver had a band of devoted followers that kept it in production for a longer period than it deserved. A c·o mparison between a TRF and a superheterodyne receiver would soon prove that the superhet is the better of the two. But despite this, many listeners preferred the TRF because of its straightforward design and simple alignment procedures. A TRF receiver can have from one to three stages of tuned radio frequency amplification prior to the detector stage. It may or may not have reaction but if it has the set will give a better account of itself. A good TRF will also have a couple of audio stages as well. In other words, a TRF receiver has no frequency converter valve Early TRF receivers had individually controlled tuning stages. This particular set has two stages of radio frequency amplification ahead of the detector. 6 SILICON CHIP or intermediate frequency amplification stages such as a superhet has. The TRF simply amplifies the radio frequency input from the aerial, detects that signal and further amplifies it in the audio section. Perhaps the worst aspect of a TRF receiver is its poor selectivity. Nearby radio stations will occupy a considerable portion of the dial compared to a superhet. This is particularly evident with smaller TRFs having only one stage of RF amplification. Such sets have very poor selectivity and there could be positions on the dial where two or three programs can be heard simultaneously. TRFs with two or three RF stages are much more selective but still do not approach the selectivity of a superhet. Most TRF receivers have two or three aerial terminals and using these to advantage will make the receiver more selective. So too will increasing the rear.tion control if the set has reaction. As the reaction is increased to almost the point of oscillation, selectivity improves greatly. However, although a reaction control gives a considerable boost to volume and can improve selectivity, it also gives rise to distortion when used at maximum levels. TRF receivers are comparatively rare and to find such a set today is indeed a lucky break. TRFs are very collectible items, even if they do not perform as well as a superhet. Most TRFs, particularly the ACoperated receivers from the early 1930s, are easily restored due to their relatively simple construction, but one can always strike unexpected problems. The 5-vafoe TRF shown in the ac- The chassis of the old 5-valve TRF receiver scrubbed up really well. A TRF receiver has no frequency converter or intermediate frequency amplification as in superheterodyne models. This beautiful TRF console model should be sufficient proof that TRFs are very collectible. It is the 5-valve unit mentioned in the story and was recently restored by the author for a friend. This close-up view shows a typical TRF layout. The valve, coil and tuning gang section of each RF stage are in line. The three grid-cap RF valves are type 24As. companying photographs gave more than its fair share of trouble. The speaker was a total write off with a busted cone and open circuit field coil and speaker transformer. The set had only one valve and the dial was jammed up solid. The power cord had been cut and much of the wiring needed replacing, not to mention numerous other incidental repairs. What's more, as the set belonged to a friend, it would have to be a job at minimum cost. A few preliminary checks are always in order before starting a restoration job and the power transformer was checked out to see if it was still operative. Both the high and low tension windings were OK. Likewise the radio frequency coils. At that stage of the proceedings the set appeared to be restorable. When repairing an old receiver for someone else, it is important to find out what type of restoration the owner wants. In this case, the owner was only interested in getting the set working again and whether it was original or not didn't really matter. That suited me because of the speaker problem. I haven't many spare electrodynamic speakers and really didn't want to part with one. Therefore, a relatively modern permag speaker was used as a replacement. Now that type of repair will make some readers shudder with disgust and as the replacement speaker was made in Brazil, it makes the originality aspect even worse. However, I was only doing what the owner wanted and what was practical. What's more, the end result sounded very good indeed. A little experience always helps when selecting unknown valves for an ancient receiver. A 4-pin rectifier socket suggested that an 80 would do nicely in that particular location. A 5-pin output socket indicated that an old 47 should work OK and two 24As should restore the radio frequency stages to working order. The owner was given the phone number of a valve supplier and I suggested that he obtain an additional valve of each type for spares. The seven valves cost $90 which really isn't expensive considering their age. Nearly all TRF receivers were made prior to 1935 and, as a result, are usually fitted with 2.5V valves. Many of these old valve types are AUGUST 1990 7 The high-tension dropping resistor in the 5-valve chassis was open circuit in one of its sections (near crosses). This problem was overcome by bypassing this section with a wirewound resistor. This old chassis shows an early attempt to gang individual tuning capacitors. They are rack and pinion driven from a single central dial. Note the small trimmers at the front of each tuner to correct misalignment. fairly rare and one major problem regarding the restoration of a TRF receiver could well be obtaining suitable valves. In some instances, substitutions may have to be made. Scraping plates Restoring an old valve radio is simply a matter of repairing or replacing worn and defective components. On this particular receiver, one thing that really needed repairing was the tuning capacitor. The tuner was a 3-gang type with a nasty problem - all the plates of all three gangs were scraping. The tuner was a plain 8 SILICON CHIP bearing type with riveted end plates. In this instance, the small brass rivets had come loose, allowing the main shaft to move forward under the pressure of a strong spring that took up the end float in the shaft. Trying to re-rivet the end plates was impossible because there was no room to fit anything inside that was strong enough to hammer on. One can only rivet if the rivet head is backed up by something solid. A different approach was tried. The loose end plates were pulled into position using G clamps; then Superglue was run into the joints to secure the endplates in position. This was followed by a couple of dabs of solder to ensure that the end plates were electrically connected to the main body of the tuner. The Superglue repair was completely successful and holds the end plates far better than the original brass tubular rivets ever did. Finally, the capacitance of the three gangs was checked with a digital multimeter and corrective adjustments were made to the outside movable plates. The tuner tracked very well for two thirds of its travel, but one gang wandered off a bit over the rest of the movement. Nothing much could be done to correct this error. Removing the tuning capacitor from the chassis makes cleaning up much easier and the chassis was wire brushed and repainted. By this stage of the proceedings, the old TRF looked a good deal better than before. The previously mentioned tight dial mechanism was mainly due to the problem with the scraping tuner plates and the gear driven dial mechanism required no further maintenance other than a thorough clean and a smear of grease. The dial lamp holder, however, required attention as it had come apart. Like the tuning capacitor, the dial lamp holder was of riveted construction and had come apart due to poor assembly. The repair required a couple of fibre washers for insulation and a few drops of Superglue to hold everything together. Handy stuff, Superglue! It is jobs such as the dial mechanism and the lamp holder repair that come under the heading of " incidentals". While nothing much in themselves, they collectively add up to quite a lot of time at the end of any restoration project. The next item to check out was the 10k0 wirewound volume control. A multimeter check indicated serious internal problems and it was replaced with a modern counterpart. As mentioned in previous stories, modern wirewound potentiometers have very short control shafts and so an extension shaft was fitted to overcome this problem. This 4-valve TRF radio has only one RF stage and no reaction. It is a very poor performer indeed. The styling is hardly a thing of beauty either. As the high tension supply was still connected to the original electrolytics, it seemed like a good idea to replace them. Likewise with half a dozen paper capacitors. In keeping with many early AC receivers, the high tension was exceedingly high and 600 volt electrolytics were used on both the input and the output sides of the HT filter. Originally, the speaker field coil was part of the HT filter, but as the electrodynamic speaker was to be replaced with a permanent magnet speaker, a substitute field coil was used. Unfortunately, the original loudspeaker was in such a poor condition that the field winding resistance was illegible. When this is the case, a suitable resistance must be built up so that the HT filter output voltage is approximately 250 volts when the set is operating. As the set was not operative at this stage, a 2k0 20W resistor was wired into the circuit in place of the speaker field coil. If its value needed to be increased or decreased, it could be sorted out later on. The speaker plug and socket then had to be rewired to suit the new arrangement. The speaker transformer also had to be wired in somewhere and this was mounted under the chassis for convenience. It's not a bad idea to do this becaus'e it keeps all the high voltage components out of the way. The worst thing that could happen to probing fingers in the back of the set is a mild burn from a hot valve. A few more incidentals needed attention. The frayed grid cap connections were tidied up. A few carbon resistors were also checked and although they had gone high, they were still close enough to their original 20% tolerance. Waggling a couple of suspicious looking solder joints revealed two exceedingly bad connections which were carefully resoldered. A couple of mica capacitors were also checked and found to be OK. One component that would have caused trouble if it had not been inspected was the high tension dropping resistor. In this case the resistance winding between two taps was open. Rather than replace the whole unit, the faulty section was bridged across with a wire wound resistor. The value of this resistor was estimated by measuring the resistance of a similar length of the dropping resistor in an unbroken section. Silence is not golden . It was time to see if my many hours of work had restored this old TRF to working order. The valves were inserted, the speaker plugged in, the aerial and earth connected, and the set switched on - nothing but silence. Total silence! The rectifier did not light up. A quick check showed that green corrosion on one of the socket contacts was possibly the cause of the trouble. With no valves in the sockets for so many years, it was not surprising. Try again. Success - all valves light up and music fills the room. The final job was to adjust the trimmers on the tuning capacitor and the task was completed. This 5-valve TRF receiver was the second radio of that type I had worked on in less than a fortnight. The 5-valve model was a much better performer than the 4-valve one, but neither can match a superhet.~ Resurreetion Radio The original vintage wireless specialists Our skilled technicians offer QUALITY repairs & restoration . We have a large stock of bakelite and timber radios fully restored and for sale. Valves, high voltage capacitors and other specialised parts available. ADDITIONAL SERVICES COPIES OF: CIRCUIT DIAGRAMS $5 .00 SERVICE MANUALS $10.00 AVAILABLE FOR MOST MAJOR AUSl. MAKES FROM 1934 ONWARD. WANTED - valves, radios , etc., purchased for cash . Call in to our showroom at: 51 Chapel Street, Windsor, Vic 3181 PO Box 1116 Telephone: (03) 529 5639 SOUND AUSTRALIA can offer you semi conductors passive components tools - hardware Hy-0 coloured mic cable neutrik-cannon connectors public address systems project cases + many more! 10% OFF EVERYTHING AUGUST ONLY ph (03) 791 1622 28 Walker St, DANDENONG 3175 AUGUST 1990 9 ··. /~ hardware : lBONANZA! fl,JJJ we are over-stocked•.. these lines must be cleared! i NUT & BOLTi PaAtH C_ KS C 100 0 68A $1.95 Cat H-10 10 4 45 BA t ~ ~ ijjlJ ijjlJ ~ 9mm HEX. 4BA TAPPED SPACERS CatH-1842~ ~ 6pk s2so PCB TRANSISTOR BA TYPE , TERMINAL BLOCK MOUNTING KITS NUTS AND BOLTS Cat H - 6 7 4 ~ · TO-220 TYPE MICA WASHER AND BUSH Cat H-1916 5 Pack of ' Size Pack Cat Price 12mm x 4BA 10 H-1032 $1.50 4BA nut 20 H-1332 1.85 2ss $ , RUBBER GROMETS •Hole Size 8mm 12mm 16mm Pack No 10 10 8 Cat No Price Pk H-1712 $1.95 H-1716 2.25 H-1719 2.50 RUBBER FEEToo RIGHT ANGLE BRACKETS ~ C 8~ ~ 6pka t H - 1~ ~5 (j • ' s7ss Screw on H-1736 $2.95 Stick on H-1740 1.50 Stick on square H-1745 1.95 ~a~~;;~eBR;;; "'-- PCB SPACERS CABLE TIE PACKS~~ll))ll"" OF 100 0 Cat H-1986 110 x 2.5mm Cat H-1988 160 x 3.5mm Cat H-1990 100 x 2.3mm Cat H-1992 (with ID tags) 100 x 2.3mm s12ss s13ss S14ss sg95 $3.95 4.50 <at>;;<at>!-:,t,)<at>-O 10mm 15mm 20mm 25mm 5 5 5 5 H-1861 H-1862 H-1871 H-1872 ~& TO-3 TYPE MICA WASHER AND 2 BUSHES Cat H-1917 0 Pack of4 $1.95 ~MICA 0 .~.,, TO-3 TYPE INSULATING Cat H-1918 CAP 95c • ~~!s~1sher (steel) 50 H-1488 1.45 !~~h~-;roof 50 H-1486 1.95 12mmx6BA 25 bolt (brass) 6BA nut 25 (brass) H-1092 3.95 H-1342 1.85 ©<at> 6BA Pack - 12 x 12mm bolts, brass nuts, and washers Cat H-1684 $4.95 SBA Pack12 x 12mm brass bolts, nuts, and washers Cat H-1682 $5.95 V ~ ~ SELF-TAPPING SCREW PACKS NYLON NUTS AND BOLTS Size Pack Cat Price No. 4 x 12mm 25 H-1612 $1.50 size 40 No.4x6mm 25 H-1611 1.25 size 40 No.8 x 12mm 25 H-1632 1.75 size 30 Size Pack Cat Price No. 4 x 6mm 500 H-1625 10.95 12mmx4BA 10 H-1012$1.75 Bulk Pack 25mm x 4BA 10 H-1022 1.95 4BA Hex nut 12 H-1302 2.75 2BA washer 12 H-1452 1.25 Cross pan-head screws t o ' 12mm x 6BA 10 H-1032 1.50 suit most switches with 25mm x 6BA 10 H-1042 1.75 threaded mounting holes. 6BA Hex nut 12 H-1312 2.95 Cat H-1674 6BA washer 12 H-1462 1.25 Pack of 10 $120 1 2;:50 Type: Round 4BA hole Length Pack Cat Price 1 6mm 12 H-183 $5. 50 9mm 10 H- 183 2 5.50 12mm 8 H-1833 5.50 5.50 25mm 6 H- 1834 Type: Hexagonal ~\ ~ 11~.__..,, 4BA tap ~....i. 12mm 6 H-1843 25mm 4 H-1847 Type: Insulated $l .5o $3.95 4.25 4.50 4.75 SWITCH SCREWS hardware BONANZA! This new Australian designed case has 3 circuit board slots, a snap fit cover, and provision for bar mounting. Its dimensions are 155x100x75mm. WAS $9.95 Cat H-2597 METAL PROJECT CASE An attractive two-part case with ventilating side slots finished in blue and grey. It's 160x130x50mm and ideal for all your small instruments. Cat H-2762 95 A sturdy plastic tool box with two full width trays, metal latches, and large carrying capacity. Cat H-2570 ONLrS12 HEATS/NKS- -~ ~- - - - - - - - To-a T Y P E . POWERFIN~ MINI PCB HEATSINK Cat H-3401 T0-5 TYPE~ ROUND Cat H-3400 Cat H-3402 s350 s1e5 s1e5 95c For the greatest possible heat dissipation in the smallest possible space. Measures 50x50x26mm. Suits all flat semiconductors and has fluted fins for maximum thermal efficiency. The universal hole pattern on this Heatsink provides mounting for nearly all 'power' semiconductors. Designed to ensure a snug fit around the transistor and provide the best possible heat transfer. SNAP-ON HEATSINKs• VERSATILE POWER ECONOMY POWER HEATSINK mounting design with fins top and HEATSlmmrr, Flat bottom. Available undrilled or pre- Cat H-3412 drilled for 2 TO-3s. Measures 74x102x25mm. T0-220 style Cat H-3416 $195 T0-126 style Cat H-3417 $185 The fast and efficient way to control heat dissipation on PCB mounted power transistors. They can be fitted in seconds and are available in two common sizes. Mounts flat or at right angles to the panel and has tongue & groove couplings to interlock with a second heatsink. Measures 78x110x33mm undrilled or pre-drilled for 2 TO-3s. cat H-3460 Undrilled cat H-3461 Pre-drilled s725 s75o cat H-3470 Undrilled Cat H-3471 Pre-drilled 595 5625 5 (' ~ WITH A 386S1 FROM - -- .... ... ......... 1iw·1n~e:~~ tookTD m --~....,.._,.._ 32 Bit Computing Power without The 5 digit Price Tag! ~ HERE ARE 4 GOOD REASONS WHY YOU'LL BUY YOUR FUTURE COMPUTER FROM DICK SMITH ELECTRONICS.... 2 THE QUALITY Twinhead computers are constructed using the latest surface mount technology fo r improved reliability. All controls are conveniently located on the front panel and the AT keyboard has a smooth, bounce-free design to keep up with the fastest typists. Your Superset-590 Computer has undergone extensive testing b efore it leaves the factory. To ensure it has arrived safely, our own Quality Control Department then puts EVERY Twinhead computer through 24 hours of rigourous testing and has given you r new computer a 100% d iagnostic test... even formatted and tested your Hard Drive. Yes, you can trust your business to the computer you buy from Dick Smith Electronics! .ti liiliw · 4 ' ··~:,;z • • • • • • • • • • 1 l THE COMPUTER • Twinhead-590 AT compatible • Super fast 16MHz 80386SX processor with 80387SX Maths co-processor Keyboard switchable processor speeds 1Mb RAM expandable to 5Mb on board Shadow RAM feature 40Mb Hard Drive & high density 5¼" Drive 2 x 1" and 1 x half height drive bays 4 free expansion slots MS.DOS 4.01 Operating System 2 serial & 1 parallel port Paradise VGA graphics adaptor with 256k (expandable to 512k) Graphics Memory VGA monochrome Monitor socket for 3 THE SUPPORT Think of a computer question and ou r support staff will know the answer! If you have a p roblem using any of our computers or software, or just need some good advice, our support staff are wa iting fo r your c a ll. Computer Service Hotline 888 2002 SERVICE TOO! Service is not a p roblem with a computer you buy from Dick Smith Electronics. We have a computer service plan to suit YOUR needsYour Dick Smith Electronics Store IS your service centre. We'll rush your computer to our Service Department and have it repaired in no time. We can arrange a Field Service agreement too, with one of Australia's largest PC service organisations - BULL HN INFORMATION SYSTEMS. Their TotalCare Engineer will come to YOU and in most cases your computer will be repaired ON TFIE SPOT! Your 12 Month Warranty can become 12 months TotalCare Field Service for just $150. 24 months of TotalCare Servic e can a lso be arranged. • NSW • Albury 21 8399 • Ba nkstown Square 707 4888 • Belconnen (06) 253 1785 • Blackta,.,n 671 7722 • Brookvale 905 044 1 • Bondi 387 1444 • Campbelttcmn 27 2199 • Chatswood Chase 4 11 1955 • Chu llora 6428922• Gore H,11 439 5311 • Gosford 250235• Hornsby 477 6633 • Hurstville 5808622 • Kotara 562092 • Liverpool 600 9888 • Maitland 33 7866 • Miran da 525 2722 • Newcas1le 61 1896 • North Ryde 878 3855 • Parramatta 689 2188 • Pen rith 32 3400 • Railway Square 21 1 3777 • Sydney City 267 9111 • Tamworth 66 1711 • Wollongong 28 3800 • ACT • Fyshw1ck 80 4944 • VIC • Ballara1 31 5433 • Belmont 43 8522 • Bendigo 43 0388 • Bo x Hill 890 0699 • Coburg 383 44 55 • Dandenong 794 9377 • East Brrghton 592 2366 • Essendon 379 7444 • Footscray 689 205 5 • Franksfon 783 9144 • Geelong 232 7 11 • Melb ourne City 399 Elizabeth St 326 6088 and 246 Bourke St 639 0396 • Richmond 428 1614 • Ringwood 879 5338 • Sprin gvale 547 0522 •OLD• Br isba ne City 229 9377 • Buranda 391 6233 • Cairns 311 51 5 • Cher ms1de 359 6255 • Red bank 288 5599 • Rockharnpton 27 9644 • Southport 32 9033 • Toowoomba 38 4300 • Townsv1lle 72 5722 • Underwood 341 0844 • SA• Adelaide City 223 4122 • Beverley 347 1900 • Elizabeth 255 6099 • Enfield 260 6088• St. Marys 277 8977 • WA• Cannin gton 451 8666 • Fremantle 335 9733 • Per1h City 481 3261 • Midland 250 1460 • North bridge 328 6944 • TA S • Hobart 31 0800 •NT • Stuart Park 81 1977 ORDER BV PHONE OUTSIDE SYDNEY (008) 220010 Free Call Sydney Area 888 2105 4~~HE0;1; s2995 Including VGA Monochrome Monitor Add $500 for Multi-Scanning VGA Colour M o nitor B973 You'll Never See Prices Like This Again! Sharp Pocket Computer PC1248 Sharp Memory Expansion Cards • 8k RAM, 17k ROM • 16 char. display • Built-in BASIC. CatX-5132 Printer & Cassette Interface Prints Thermal hard copy from your Pocket Computer and allows you to connect a cassette recorder for data storage. CE126p $1 39 Cat. Size Price Part X-5136 X-5137 X-5138 8kRAM $39.95 16k RAM 32k RAM $49.95 $69.95 CE212M CE2H16M CE2H32M CatX-5119 Printer Paper Rolls To suit these Pocket Computers: cat x-5121 Pocket COJJlPUfer o PC1100 o. PC1270 o. # PC1280 EA23 Mains Adaptor CatX-5122$12 95 CE152 Data Cassette Recorder Designed especially for recording computer data. CatX-5140 Keyboard S99 84 key XT style keyboard with high quality ALPS keyswitches. CE124 Cassette Interface Connects your Data Recorder to the Sharp Pocket Computer. Cat X-5139 o. # PC1360 o. # PC1425 o. PC1450 CatX-3820 s399s For Cassette Recorder CE152 Mains Adaptor cat x-5141 $12 95 Hard/Floppy Disk Controller Fax Card Cal X-2020 o. # PC1460 o • # PC1475 o • # PCE500 Parallel Data Booster Break the 2 metre limit! Move your parallel printer up to 16 metres from your computer. Requires an AC adaptor. (not included) Cat X-3578 Off The Desk Kit $2995 Monitor Cable 4 Digit Capacitance Meter QQQ [t] Use it in the workshop, use it in the laboratory. This meter can measure capacitance from 1pf to 9999uf in seven ran9es. It is mains powered , which means a bi~ bright LED display, and ,t has an accuracy of better than + 1 Vo. Supplied complete with all components including plastic case , deluxe pre-punched silk screened front panel, and even alligator clips and BNC plug for test lead. Cat K-7500 S129 s99 <at> Chromavox QQQ [t] Automate your light show and let it dance to the music! The Chromavox accepts line input from an amplifier or operates independently, off its built-in microphone. This kit comes complete with a moulded plastic case plus pre-punched silk screened front panel and can ha·ndle up to 2400 watts of lighting. Cat K-3162 . s139 2 Sector Burglar Alarm Control Unit Q This Control Unit features variable entry and exit delays, LED status indicators, alarm driver circuitry, timed and latched outputs, two separate sector inputs, and the provision to add extra sector boards as required. This is a short form kit which includes all components, PCB, and IC sockets. Cat K-8401 Expand your K-8401 Burglar Alarm Control Unit. Add as many of these Sector Modules as you need. They hold two sectors, each with LED status indicators and isolating switches. Kit includes components, PCB, and IC sockets. Cat K-8400 .., ~!i.~-.-.-=-.-~ - -~ s 1295 '!..:. :- ~-~-- Combination Lock Q This keypad operated combination lock could be used to operate your K-8401 or other Burglar Alarm. Works with solenoid door locks too! It can even be wired to trigger the alarm when the lock detects repeatedly incorrect entries. The kit includes all components, PCB and high quality keypad. ' Cat K-8403 .. <at> Hot Canaries Q Electronic Dice Q This handy kit is more than just a random number generator. It displays its numbers in the traditional die format on two rows of three LEDs. You can even see the Electronic Dice counting as numbers roll by and stop just past that elusive six. Short form kit with all . components, PCB, IC sockets, and battery holder. sge5 Cat K-3532 fL1 LZJ Kits marked with this symbol involve mains power wiring. Take extreme care when working with this equipment. Degree Of Simplicity Q Simple QQ Intermediate QQQ Detailed Put your budgies out to pasture and let these Hot Canaries rule the roost! Intrigue your cat as these two birds sing their electric sox off. The kit comes with a cat-proof case, PCB, all components, and front panel label. Cat K-3530 ....... Let's Brighten Up Your Switches Keypad Matrix Switch Xenon Flashtube DPDT Lampswitch Suitable for electronic locking devices or as numeric input for any digital device. $ As used in Strobes, warning lamps, and photographic equipment. Operates on 200-400 volts with a 4kV trigger, and has 5 watts maximum input. The double pole version of P7874. Fits th e same hole but has a slightly larger body (23x15x13mm). Rated at 240Vac, 2A per pole. 50 Cat P-7804 [I) 0<at>) <at>] [II~ III 395 ~ ~ [B<at>] <at>I Neon Bulb Cat P-8164 Pigtail type neon bulb as used in indicators, timing circuits, oscillators, etc. 70-90 volts <at> 600uA. Cat P-8160 M.E.S. Bulbs Miniature Edison Screw BULBS to suit most illuminated dials. Cat P-8150 6 volt Cat P-8152 12 volt M.E.S. bulb sockets ~2c ~ 75c Cat P-8162 Car/Battery Clips Battery Terminal Clip 30A red Battery Terminal Clip 30A black Crocodile Battery Clip 20A red Crocodile Battery Clip 20A black P-6420 P-6422 P-6416 P-6418 $1 .25 $1 .25 $1 .95 $1 .95 This switch pack is ideal for audio switching applications. Each switch is DPDT and mechanically interlocked so that only one button can be activated at once. Switches spaced at 11 mm centres. Cat P-7750 • Illuminated Push Button Switches $395 4 Way Switch Pack 75c $2 Cat P-7876 A square switch with round body as used in car burglar alarms and control panels. Uses alternate make/break switch action and has an inbuilt 12 volt, 55mA bulb. Cat Cat Cat Cat s515 P-7580 P-7582 P-7584 P-7586 red blue $ green yellow 13h95 eac Dashboard Switch Single DPDT Switches to match the 4 Way Switch Pack Pull on, push off single pole switch as found controll ing lights or wipers in many older vehicles. This switch is ideal for trucks too as it's rated at 24 volts, 10A. Cat P-7752 Cat P-7562 s195 $495 SPST Lampswitch 12V Illuminated SPST The perfect replacement for a worn out desk lamp switch. Fits an 11 mm hole and is rated at 240Vac 2A. Intended for automotive use, the soft glow from the toggle is not distracting. The 12 volt lamp operates from the supply being switched (12 Vdc<at> 16A). Cat P-7874 ~ Cat P-7666 s425 DS XPRESS PHONE & MAILORDER SERVICE PHONES SECURITY AUDIO COMPUTERS Outside Sydney ( FREE Call) 008 22 6610 Sydney And Enquiries - 888 2105 FAX: (02) 805 1986 or write to DS XPRESS, PO BOX 321 N/RYDE NSW 2113 All Major Credit Cards Accepted. 0 / Nite Courier Available. 24 HOUR DESPATCH OF ALL ORDERS • NSW • Albury 21 8399 • Bankstown Square 707 4888 • Belconnen (06) 2531 785 • Blacktown 671 7722 • Brookvale 905 0441 • Bondi 387 1444 • Campbelltown 27 2199 • Chatswood Chase 411 1955 • Chullora 642 8922 • Gore Hill 439 5311 • Gosford 25 0235 • Hornsby 477 6633 • Hurstville 580 8622 • Kotara 56 2092 • Liverpool 600 9888 • Maitland 33 7866 • Miranda 525 2722 • Newcastle 611896 • North Ryde 878 3855 • Parramana 689 2188 • Penrith 32 3400 • Railway Square 211 3777 • SydneyCity 2679111 • Tamworth 661 711 • Wollongong 28 3800• ACT• Fyshwick 804944• VIC • Ballarat3 1 5433 • Belmont 43 8522 • Bendigo 43 0388 • Box Hill 890 0699 • Coburg 383 4455 • Dandenong 794 9377 • East Brighton 592 2366 • Essendon 379 7444 • Footscray 689 2055 • Frankston 783 9 144 • Geelong 232 7 11 • Melbourne City 399 Elizabeth St 326 6088 and 246 Bou rke St 639 0396 • Richmond 428 1614 • Ringwood 879 5338 • Springvale 547 0522 • QLD • Brisbane City 229 9377 •Buranda 391 6233 • Cairns 311 515 • Cherms ide 359 6255 • Redbank 288 5599 • Rockhampton 27 9644 • Southport 32 9033 • Toowoomba 38 4300 • Townsville 72 5722 • Underwood 341 0844 • SA •Adelaide City 223 4122 • Beverley 347 1900 •Elizabeth 255 6099 • Enfield 260 6088 •St. Marys 277 8977 • WA • Cannington 451 8666 • Fremantle 335 9733 • Pert h City 48 1 3261 • Midland 250 1460 • Northbridge 328 6944 • TAS • Hobart 31 0800 •NT • Stuart Park 81 1977 I ;(t) ~ i )I )f ,, ={ijl ij ,J (1/.1 ~1_ o_Ro_E_R_e_v_P_Ho_N_E_o_u_Ts_1o_E_s_v_o_NE_v_1_oo_a>_22_s_s1_o_F_ree_ca_11_s_yd-ney_A_re_aa_a_a_2,_os_ _ _ _ __ The Largest Australian Electronics Retailer! 63 Stores Across Australia _ .,: ·:., .:•.··•t:, . · m. :.:,:·;:::.•. . ·,, . . . _. :_·/i ' ~-~ . . .. .,v ... ' .· ansmI .e , By GREG SWAIN Here's an easy-to-build UHF transmitter that you don't have to adjust for frequency. It uses a SAW filter for high stability and is fully compatible with the UHF Remote Switch described in December 1989. Although designed specifically for the DSE Remote Control Switch described last December, this UHF transmitter can also be used with previous remote switches described in SILICON CHIP (eg, March 1988 & August 1988). However, this new transmitter has several improvements compared to earlier designs. These improvements have been 16 SILICON CHIP wrought mainly by scrapping the LC tuned circuit used in previous designs and replacing it with a Surface Acoustic. Wave (or SAW) filter. A SAW filter offers several advantages over an LC circuit: (1). it locks the transmitter frequency to 304MHz (303.88MHz to be precise); (2). it eliminates the need for transmitter alignment; and (3). it means that there is very little frequency drift due to hand capacitance or temperature variations. Another advantage of this transmitter is that it automatically ceases transmission after about 10 seconds if the button is accidentally (or purposely) held down. This can easily occur if you put the transmitter in a pocket. As well as extending battery life, this feature is now also a DOTC (Department of Transport and Communications) requirement. As can be seen from the photos, the circuit fits in a plastic keyring style case and is powered by a 12V lighter battery. A red LED flashes when the button is pressed to indicate that the unit is operating. In essence, the new transmitter duplicates all the features of the commercial transmitter supplied with the Dick Smith Electronics UHF Remote Control Switch (SILICON CHIP, December 1989). That design also used a SAW filter but unfortunately is now becoming difficult to obtain. The unit described here will be used as a replacement transmitter in future kits or can be built simply to provide additional transmitters for the remote switch. A complete kit of parts for the project will be available from Dick Smith Electronics [see panel). How it works Fig.1 shows the circuit details of the UHF Remote Transmitter. It uses a digital encoder IC to key a UHF oscillator operating at 304MHz [Ql) on and off. ICl is a Motorola MC145026 9-bit trinary encoder and is used to generate a 9-bit code word. Trinary code is similar to binary code except that there are three logic states instead of two [ie, high, low and open circuit). The 9-bit code word is selected by the connections to ICl's nine address pins, Al-A9. In practice, this means that each address pin can be tied to the + 12V rail, to ground or left open circuit, thus giving 19,683 combinations. However, because of the particular decoder IC used in the receiver [MC145028), A9 should only be tied high or low and this reduces the number of coding options to 13,122. In fact, in the DSE receiver (SILICON CHIP, December 1989), A9 is tied to ground which means that A9 in the transmitter must also be tied to ground. The 9-bit serial data is shifted by an internal oscillator in ICl, the frequency of which is set to 770Hz by the RC timing components on pins 11, 12 & 13. Pin 14 is used to control ,the transmission. When S1 is initially pressed, this pin is low and the internal oscillator is enabled to shift the data out. The 33µF capacitor on pin 14 of IC1 now charges via an internal pullup resistor. After about 10 seconds, the voltage on pin 14 100(! + 47k 16 -T 1 2 3 Al 14 + 33 16VW A2 A3 47k 15 1k !Cl MC145026 A5 SAW 6 FILTE{1=--f * J 5.6pFl .,. A6 13 7 * 3.3pF 4 A4 5 .001! - * SEE TEXT 56k A7 12 .01 g AB c<at>e A~K 11 120k VIEWED FROM BELOW 10 A9 .,. HIGH ST ABILITY UHF REMOTE TRANSMITTER Fig.1: the circuit uses an MC145026 trinary encoder IC to key UHF oscillator Ql on and off. The SAW filter sets the output frequency to 303.8MHz while inputs Al-A9 are connected to give the address code. reaches logic 1. When this happens, the internal oscillator stops and data transmission ceases. The 47k0 resistor is there is discharge the 33µF capacitor when S1 is released, so that the circuit is ready for the next transmission. During transmission, the output from pin 15 consists of a series of pulses and these are used to modulate the external oscillator (Ql). The frequency of this oscillator is set to 303.8MHz by the SAW filter in Ql 's base circuit. The 3.3pF capacitor between collector and emitter provides the necessary positive feedback to ensure oscillation. Another capacitor (5.6pF) is used to bypass the 4700 emitter degeneration resistor to increase the oscillator output. This output appears at Ql 's collector and drives a transmission line antenna which actually forms part of the PCB pattern. The PCB fits neatly into a small keyring case and is powered by a 9V lighter battery. The SAW filter locks the output frequency to 303.8MHz and eliminates drift due to hand capacitance. AUGUST 1990 17 PARTS LIST auaa A6A5A4A3A2A1 Fig.2: keep all component leads as short as possible when assembling the PCB. The SAW filter is oriented so that the side closest to its four pins is adjacent to the lkn resistor. Inductor L1 is part of the PC pattern. Fig.3: to code the transmitter, each A1-A9 input is connected to the high rail, the low rail, or left open circuit. If the unit is for use with the DSE receiver, then tie A9 low. Be sure to match the receiver code. 1 transmitter case 1 PC board, code ZA-1432 (copyright Dick Smith Electronics) 1 PC-mounting pushbutton switch 1 SAW filter (303.8MHz) 1 12V lighter battery (GP23 or equivalent) Semiconductors 1 MC145026 trinary encoder (IC1) 1 PN3563 NPN transistor (01) 1 red LED (LED 1 ) Capacitors Power is derived directly from the 12V battery and is applied to the circuit via push button switch S 1 and LED 1. During transmission, LED 1 flashes due to variations in the current drawn by ICl as it outputs the serial data stream. At the end of the transmission, LED 1 will remain dimly lit due to the circuit's quiescent current consumption. Building it All the parts for the UHF transmitter are mounted on a small PC board. This board is coded ZA-1432 and fits into a plastic keyring-style case. Fig.2 shows the parts placement diagram. You can install the parts in any order but we suggest that you leave the IC and the switch until last. Keep all resistor and capacitor leads as short as possible and use your multimeter to check the resistor values before installing them on the board. Note carefully the orientation of the SAW filter - the edge closest to the four pins goes towards the IC. Transistor Ql is mounted with its leads bent at right angles and with the flat side of its plastic body sitting flush against the PCB. The leads of the 33µ,F tantalum capacitor are also bent at right angles so that the device can lie flat on the board. Install this capacitor so that its positive ( +) lead is closest to the IC. This done, install the switch with the flat side of its body towards the battery, then install the two PC-mounting battery terminals. The LED should be installed so that its top sits about 13mm above the board. That way, it will just pro- 1 1 1 1 1 33µ,F 16VW tantalum .01 µ,F ceramic .001 µ,F ceramic 5.6pF ceramic 3.3pF ceramic Resistors (0 .25W, 5%) 1 120k0 1 56kQ 2 47k0 1 1 kO 1 4700 1 1000 trude through the hole in the lid when the case is assembled. Check that the LED has been correctly oriented (the anode lead is the longer of the two) before soldering its leads. Coding Before testing, the A1-A9 address pins must be connected to match the receiver code. This simply involves tying each pin high, low TABLE 1: RESISTOR CODES □ □ □ □ □ □ □ Value 120k0 56k0 47k0 1k0 470Q 1000 No 1 1 2 1 1 1 4-Band Code (5%) brown red yellow gold green blue orange gold yellow violet orange gold brown black red gold yellow violet brown gold brown black brown gold TABLE 2: CAPACITOR CODES □ □ □ □ □ 18 Value .01 µ,F .001µ,F 5.6pF 3.3pF SILICON CHIP All Value 10nF 1nF IEC Code 10n 1n 5p6 3p3 EIA Code 103 102 5.6 3.3 Before mounting Ql, bend its leads at right angles then install it so that the flat of its body rests against the PCB. The 33µF capacitor is mounted in similar fashion. Why Kill your Computers Memoryl COMPUTER PROTECTOR The transmitter output drives inductor Ll which is a transmission line antenna etched into the PCB pattern. This transmitter has been coded by tying A1-A4, A6 & A9 low and by leaving A5, A7 & AB open circuit. or open circuit. For example, you could connect A1 to the high rail, A2 to the low rail, leave A3 open circuit, bridge A4 low and so on. Note that if the transmitter is for use with the DSE receiver, then A9 (pin 10) must be tied low (ie, connected to ground). Fig.3 shows the A1-A9 address pins on the copper side of the PC board, together with the locations of the high and low rails. Use solder bridges or short lengths of tinned copper wire to connect the selected address pins to the high or low rails. Once coding has been completed, the PCB and battery can be installed in the case and the unit tested with its receiver. Note that it may be necessary to retune the receiver so that it matches the transmitter frequency. The range achieved will depend on whether or not an antenna is fitted to the receiver but distances of up to 25 metres in open space should be possible. Note that the value of the feedback capacitor between collector and emitter of Ql is critical. If the circuit does not oscillate with 3.3pF, increase the value to 3.9pF. How can you tell? Simple - the LED will flash when the button is pressed but the transmitter just won't work. Finally, you will have to slightly modify the receiver circuits of March & August 1988 for use with this transmitter. In each case, change the 39kQ resistor on pin 6 of the MC145028 decoder IC to 56k0 and the 180k0 resistor on pin 1O to 390k0. 1§:;l Where to buy the kit This project was developed by Dick Smith Electronics and is available from all DSE stores or by mail order from PO Box 321 , North Ryde, NSW 2113. You can also order by phone on (02) 888 2105 or, from outside the Sydney area, on (008) 22 6610. The kit consists of all parts including the case and the battery. The price is as follows : UHF Remote Transmitter (Cat. K-3259) ... .... ... ....... ..... ..... ... $29.95 Postal orders should include another $3.00 for packaging & postage. Please quote the catalog number when ordering . Note: copyright of the PCB artwork associated with this project is retained by Dick Smith Electronics. ~~~ Or Risk the Loss of Expensive Data? Available in the following Current Ratings: l Amp 3 Amp 6 Amp 10 Amp Install o COMPUTER PROTECTOR A definite must for all electronic office equipment ..-----■ cmi:mi ■ ~ ~Ls!,Lng~se I SYSTEMS WESTINGHOUSE BRAKE & SIGNAL COMPANY (AUSTRALIA) LIMITED SIGNAL DIVISION 80-86 Douglas Pde. Williamstown. Victoria. (P.O. Box 267, Williamstown. Victoria. 3016) Phone (03) 3971033. Fax (03) 397 1861 Telex : 37 477 Wessys Vic(03) 3971033. NSW (02)5451322, Old (07) 275 3188 SA: (08) 212 3161 . WA:(09) 446 8844 COM/2 AUGUST 1990 19 Universal safety timer for irons & kettles How many times has someone in your house left the iron on or allowed the electric kettle to boil dry and burn out the element? This circuit solves those problems by automatically switching off the power after 9 minutes unless a reset button is pressed. An alarm warns of impending power shutdown. By JOHN CLARKE Although specifically intended for use with irons, this Iron Timer can also be used with many other appliances. It is an in-line device which plugs into the power point, while the controlled appliance (an iron, electric kettle, lamp etc) plugs into the timer itself. A Triac is used to control the power of the appliance while CMOS ICs perform the timing function. When first switched on, the Iron Timer supplies power to the ap- pliance for 9 minutes and then sounds an alarm. If the reset button is now pressed, the timing cycle restarts and the unit supplies power to the appliance for another 9 minutes. However, if the reset switch is not pressed, the power switches off after a further 16 seconds. Because mains voltages are involved and some heatsinking is required, the project is housed in a diecast metal case which is secure- The Iron Timer can be used with appliances rated up to 2.4kW. It is installed in series with the appliance and automatically switches off the power after 9 minutes unless the Reset button is pressed. 20 SILICON CHIP ly earthed. The two power leads emerge from either end of the case - one fitted with a 3-pin plug and the other with a 3-pin mains socket. The reset switch is on the lid of the box, along with a LED power indicator. Before electing to build this project though, you should note that it is unsuitable for use with inductive loads such as induction motors. Apart from this limitation, you can use the project with virtually any appliance that presents a resistive load and is rated up to 2.4kW. It's also quite easy to vary the time-out period over quite a wide range. This involves altering an RC time constant in the circuit to give the required period - more about this later. How it works Fig. l shows the circuit details. It uses 3 CMOS ICs (ICl-3) for the timing function plus an optoisolator (IC4) to drive the Triac (TRIACl). Note that this circuit is potentially dangerous. If you touch components inside the box while it is powered up you could be electrocuted. That means you could be DEAD! If you are not confident about building a purely mainspowered circuit with no isolating transformer, then give this one a miss. Having scared off half our readers, let's look at the circuit in more detail. The low voltage supply for the circuit is derived directly from the mains via the 0.47 /.lF capacitor which drops most of the mains potential via its reactive impedance. A bridge rectifier (Dl-D4) rectifies (what else?) the incoming AC and the output is limited to 15V DC by zener diode Dl and filtered by another 470/.lF capacitor. The 470!1 1W resistor limits the initial switch-on surge current to a safe Fl 10A 0.4 7 250VAC S1 RESET +15V I 680!! 1W 3 014 1"-_.,--J--k--l--' 10k 01 BC328 IC2 4020 .056!. OSCILLATOR 1M IC1 7555 MASTER OSCILLATOR DIVIDER/COUNTER B EOc VIEWED FROM BELOW CASE value for the rectifier diodes and the 470µ,F capacitor. Note that the + 15V line on the circuit is positive with respect to the Neutral line. If the wall outlet is wired correctly, you could safely touch any part of the low voltage circuit and not get a shock. But if the wall outlet (power point) has the Active and Neutral transposed, then all the low voltage portion of the circuit will actually be sitting at the full 240V AC and will therefore be extremely dangerous. So don't -consider doing anything to this circuit while it is powered up. OK? Having said that, it is possible to safely test the circuit by powering it from a low voltage supply. We'll tell you how to do that later in the article. Timing oscillator ICl is the master oscillator for the circuit. This stage consists of a CMOS 7555 timer which is connected for astable operation. Its output frequency is set to 15 .2Hz by the lMO resistor and .047µF capacitor on pins 6 & 2 and so these components determine the period for which the appliance is on. The 555 timer stage works like this: Initially, the output, pin 3, is LOAD IRON TIMER Fig.1: the circuit uses a 555 timer (IC1) to clock a 4020 binary counter (IC2). IC2's Q outputs in turn control Schmitt trigger gates IC3a-d and these drive transistor Qt and the piezo transducer. IC4 controls TRIAC1 which switches the load current. high and so the .047µF capacitor begins charging via the lMO resistor. When the voltage across the capacitor reaches 2/3Vcc (after time 0.695RC), pin 3 switches low and the capacitor then discharges via the lMO resistor until it reaches 1/3Vcc. This switches pin 3 high again and thus the cycle is repeated indefinitely to give a 15.2Hz square wave output. This 15.2Hz signal is used to clock IC2 which is a 4020 14-stage binary counter. When power is first applied or the reset switch is pressed, the reset input (pin 11) of IC2 is pulled high and this sets all the Q outputs low. As soon as Sl is released, the 10µ,F capacitor quickly charges via the 1ookn resistor and this pulls pin 11 low to release the reset. IC2 now begins to count the clock signal from ICl. Four Q outputs of IC2 control three Schmitt triggers, IC3a, IC3c & IC3d. Let's look at IC3a first. After reset, Q9 and Q14 of IC2 are low and pin 3 of IC3a is high. This means that pin 4 (reset) of ICl is also high and so ICl is enabled (ie, it oscillates at 15.2Hz). At the same time, pin 4 of IC3b will be low and thus transistor Ql , LED 1 and the internal LED in IC4 are all on. The internal LED in turn activates the optical Triac in IC4 and this drives the gate of TRIACl to switch power to the load. The low on Q 14 also pulls pin 8 of IC3c low. Thus, pin 10 of IC3c remains high and no sound is produced by the piezo transducer. At the same time, Q14 pulls pin 13 of IC3d low via diode D5 and this prevents IC3d from oscillating. This is done to ensure that there is no low-level feedthrough to the piezo transducer. The circuit remains in this state until Q14 goes high which does not happen until 535 seconds, or about 9 minutes, have passed. When Q14 goes high, it pulls pin 8 of IC3c high. At the same time, diode D5 is reverse biased and pin 13 of IC3d is pulled high by its lOOkO resistor. IC3d then begins to oscillate at about lkHz, as set by the 10k0 resistor and .056µ,F capacitor at its pin 12. This is the signal that drives AUGUST 1990 21 Fig.2: here's how to wire up ·the Iron Timer. Check that the mains cords are securely clamped and be sure to use 240V AC cable for all mains wiring. The Triac is bolted to the bottom of the case and this provides the necessary heatsinking. 0 MAINS CORO FROM MAINS \ CORO CLAMP GROMMET ,J ~-------< I CORO CLAMP GROMMET 1---------1 TO LOAD 0 0 0 3 4 AUK LE01 0 0 RESISTOR CODES □ □ □ □ □ □ □ No 1 2 Value 1MO 100k0 10k0 68on 4700 3900 2 1 1 1 the piezo transducer. Actually, a flat lkHz tone produced by the piezo speaker is not very noticeable. To make it more noticeable it is modulated on and off by the Q4 output of IC2. Q4 goes high for 520ms and then low for 520ms continuously, and this low frequency square wave modulates IC3d via diode D6. Now consider the Q9 output. It goes high 16.7 seconds after Q14 goes high, during which time the 4-Band Code brown black green gold brown black yellow gold brown black orange gold blue grey brown gold yellow violet brown gold orange white brown gold piezo oscillator is enabled. Actually, Q9 will have been changing state every 16.7 seconds but it does not come into play until this moment. When Q14 and Q9 go high together, IC3a's output goes low. This signal is inverted by IC3b which drives transistor Ql. With Ql 's base now pulled high by IC3b, it has no choice but to turn off. This turns off the optoisolator (IC4) and so the Triac turns off too. The other result of IC3a's output CAPACITOR CODES □ □ □ □ 22 Value 0.47µF .056µF .047µF Alt Value 470nF 56nF 47nF SILICON CHIP IEC Code 470n 56n 47n 5-Band Code brown black black yellow brown brown black black orange brown brown black black red brown blue grey black black brown yellow violet black black brown orange white black black brown EIA Code 474 563 473 going low is that it pulls pin 4 of ICl low. This stops ICl and so the circuit stops operating altogether. Reset If the reset switch is pressed before the load is switched off, IC2 is reset and mains power is maintained for another nine minutes or so, when the circuit will again switch off the power. Alternatively, if the circuit has already powered down and the reset switch is pressed, the power is restored to the load for another nine minutes or so. Note that by increasing the timing capacitor at pin 2 of ICl, the overall timing period can be increased in proportion. Want the circuit to run for ten times as long WOOD FOR CHIPS ... WOOD FOR CHIPS ... WOOD FOR CHI PS ... WOOD FOR CHIPS .. WOOD FOR CHIPS .. WOOD FOR CH IPS .. WOOD FO f;; C MULTIMETERS EDM1133 Digital Multimeter • 8 Autoranging Functions Vdc, Vac, Ade, Aac, Ohms, Diode, Continuity etc. • Analog Bar Graph • Range Hold • 3 3/4digits EDM1133 $172.60 ($148.80) ~ i5 a: 0 I.I.. Cl 0 ~ ~ ::t: u a: 400A Clamp Meter • 20A to 400A ac • 750Vac • Peak Hold DCT300 $126.95 Fluke 80 Series ... 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Don't substitute for any of the specified parts and don't work on the circuit while it is powered from the mains - it could be dangerous (see warning panel). - ie, 90 minutes? Simple - just increase the .047 µ,F capacitor to 0.47µ,F. Want it to run for around 7 hours? increase the .047µ,F capacitor to 2.2µ,F. Construction All of the circuitry for the Iron Timer is assembled onto a PCB coded SC 10107901 and measuring 100 x 60mm. It is a tight fit in a diecast aluminium box measuring 122 x 67 x 43mm. The Triac connects to the underside of the PCB so that it can be directly mounted onto the base of the box for heatsinking. Note that the specified Triac is an isolated tab device - it can be mounted directly onto the inside of the earthed case and no mica insulating washers are required. You can start construction by installing the oarts on the PCB. Install the 10 PC stakes first , then the low profile components such as resistors, links, ICs and diodes. Make sure that the diodes and ICs are in the right way around, otherwise the circuit will not work. Zener diode ZDl is installed with a loop in one of its leads. This is to 24 SILICON CHIP reduce mechanical stress as the device varies in temperature. Once the low profile components have been installed, mount the fuse clips, fuse, capacitors and the transistor. This done, mount the Triac so that the lower face of the tab is 6mm below the PCB. The tab of the Triac should overhang the PCB edge by 6.5mm. This will allow the Triac to sit comfortably on the base of the box while the PCB sits on the 6mm standoffs. Also, the overhang of the Triac allows access to the mounting screw. The PCB and Triac assembly can now be temporarily installed in the box so that the drilling locations for the PCB corner mounting screws, Triac tab and earth solder lug can be marked. Locate the solder lug position at the opposite end of the PCB to the Triac and as close as possible to the edge of the case so that the screw is accessible with the PCB in place. After drilling, all holes should be deburred using a larger drill, particularly the Triac mounting hole. The Triac is simply bolted to the case with a smear of heatsink compound between the case and the 1 PC board, code SC10107901, 1 00 x 60mm 1 Dynamark label for front panel, 120 x 65mm 1 diecast aluminium box, 1 22 x 67 x 43mm 1 plastic momentary push on mains rated switch ; DSE Cat. P- 7 5 50 (do not substitute) 1 piezo transducer 1 red LED and bezel 2 mains cord grip grommets 1 metre 1 OA mains wire 1 mains line plug 1 mains line socket 2 PCB 3AG fuse clips 1 1 OA 3AG fuse 6 6mm standoffs 4 screws and nuts for securing PCB 1 screw and nut for Triac mounting 1 screw, nut & star washer 2 screws and nuts for piezo transducer 1 solder lug 10 PC stakes 4 adhesive rubber feet 1 70mm-length of 1 0mm dia. heatshrink tubing Semiconductors 1 7555 CMOS timer (IC1) 1 4020 14-bit binary counter (IC2) 4093 quad Schmitt NANO gate (IC3) 1 MOC3021 optically isolated Triac driver (IC4) 4 1 N4004 1 A 400V diodes (D1-D4) 2 1 N914, 1 N4148 diodes (D5 ,D6) 1 BC328 transistor (01) 1 15V 1 W zener diode (ZD1) 1 MAC320A8FP 20A 600V insulated tab Triac Capacitors 1 1 1 1 1 4 70µ,F 25VW PC electrolytic 1 Oµ,F 25VW PC electrolytic 0.47µ,F 250VAC capacitor .056µ,F metallised polyester .04 7 uF metallised polyester Resistors (0.25W, 5%) 1 1 MO 1 6800 1W 2 100k0 1 4700 1W 2 10k0 1 3900 Miscellaneous Solder, heatsink compound , tinned copper wire. For Features and Performance ... 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Pt Moresby 25 6322 Lae 42 6246 ~Recommended prices only Install the zener diode with a loop in one lead to provide stress relief as the device warms up. Immediately to the left of this diode is the 0.47µF capacitor. This device must be rated at 250V AC. mounting tab to improve heat transfer. Now mark out the locations for the cord grip grommets. The inlet (plug) lead is located on the solder lug terminal end of the box. Mark out the position for this cord grip grommet in the centre of the box and 15mm below the top edge. The outlet (socket) lead is located on the Triac end of the box but is located slightly off centre away from the Triac to allow access to the Triac screw. Mark out the position for this cord grip grommet 15mm down from the top edge of the case and 15mm apart from the Triac mounting screw. Drill out the holes required and file out the cord grip grommet holes using a round file. The cord grip grommet must be able to securely grip the mains cord, so do not make the opening too large. At this stage, the holes in the lid can be marked out and drilled. The Dynamark label can be used as a guide for the hole positions. The six hole positions at the end of the label are for the piezo transducer. The four inside holes are to allow the sound to pass through the lid while the two remaining holes are for 26 SILICO N CHIP securing screws. These screws secure the transducer to the underside of the lid on 6mm spacers. Alternatively, you could use Superglue. Note that the four sound exit holes are all that are necessary for this purpose. Do not drill an extra hole in the centre since this could allow someone to make contact with the metallic disc of the transducer with a metallic object WARNING! Under some circumstances (eg, if the Active & Neutral wires are transposed at the power point or in an extension lead), the low voltage portion of this circuit will actually sit a 240V AC and could therefore be extremely dangerous. For this reason, never attempt to work on the Iron Timer while it is powered from the mains. If you do, you could get a fatal shock. The only safe way to test this circuit is to power it from a 1 2V DC source as described in the text. such as a screwdriver - a very dangerous situation. The hole for the LED is made large enough for the bezel, while you will need to drill and file out a square hole for the pushbutton switch. Incidentally, the reason we have specified this square switch rather than a larger one with a round mounting hole is to give adequate clearance to the circuit board underneath. Once the Dynamark label is secured to the lid, the holes can be cut out with a sharp knife to allow the switch, piezo transducer and LED to be mounted. The PCB can now be installed in the box. First, apply a smear of heatsink compound to the lower face of the Triac, then insert the four corner screws for the PCB. This done, install a 6mm spacer over each screw, then lower the PCB into position and do up the nuts. The Triac tab can now be secured with a screw and nut. For each of the mains cords, strip 150mm of sheathing off each cable end to allow termination to the PCB and connection of the plug and socket. The connections to the plug and socket must be as shown in the packaging information supplied with them. Secure each mains cable with the cord grip grommet and connect the leads as shown in the wiring diagram. It's best to solder the two earth leads to the solder lug before securing it to the base of the case. If you screw the lug to the case and then attempt to solder it, you may have difficulty since the case will act as a good heatsink and possibly cause a dry solder joint. Use a star washer between the nut and solder lug to prevent the nut from coming loose. Finally, install insulating sleeving over the wires running from the piezo transducer and the LED to the PCB terminals. This will prevent any tendency for insulation breakdown due to the possibility of high voltage between the wires and case. Testing When the wiring is complete, the unit is ready to be tested. Don't connect the circuit to the mains yet. In- SEE IN THE DARK with our 0 0 See EA MAY 1990: Plans for new housing included. 0 IRON TIMER RESET 0 I.!.. I!!.=- POWER ON (2400 WATTS MAXIMUM 10A FUSE INSIDE) Fig.3: here is a full-size artwork for the front panel. stead we recommend testing the circuit with a low voltage power supply set to 12V DC. The leads from the power supply are connected across the zener diode, with the positive lead going to the striped end. Do not set the supply to 15V or above otherwise the zener diode will be blown. Check that + 12V is present at pin 8 of ICl, pin 16 of IC2, pin 14 of IC3 and the emitter of Ql. That being the case, LED 1 should be lit. Now check the DC voltage at pin 3 of ICl - this should be at about half supply voltage because it is actually oscillating with a square wave output of about 15Hz. If everything is OK wait for about 9 minutes and check that the alarm sounds. When this happens, the LED should go out after a further 16 0 I a~111) C.c"E::m- INFRARED NIGHT VIEWER 0 * PCB and components kit (tripler included) $59.95 0 * Case Kit . . ..... . ..... $27.00 (no lenses) * New lnfrared Image Tubes at approx. $200-$400 * Other lower priced tubes may be available: P.O.A. 0 I BARGAIN PRICED LASERS! I -:..!1 seconds. The LED should light again if the reset switch is pressed. If the circuit does not function, check for short circuits between tracks, wiring errors and missed solder joints. You can also check the operation of each IC by measuring pin voltages. The outputs of IC2 & IC3 should be either high or low as set out in the circuit description. If everything checks out thus far, the circuit can be tested on the mains. First, secure the lid of the case, then plug the device into the mains without a load at the socket end. If the LED lights when powerd up, the Iron Timer can be tested with a load. Check that the iron (or other appliance) is initially on and that the alarm sounds after about 9 minutes. The unit should then switch off the power. ~ Complete 240V Laser Kit (EA July 1990). With 0.5-0.BmW Tube ... $239.90 With 3-4mW Tube ...... $349.50 ;~1· CURRENTLY WE ARE OFFERING THIS KIT WITH A 1-1.5mW TUBE FOR THE INCREDIBLY LOW PRICE OF ONLY ................ $269.90 TUBE ONLY: Simply subtract $110.00 from the above prices. KIT ONLY: $120.00 A DC power supply kit for HeNe laser tubes will be available at a cost of under $100.00. LASER DIODES Low voltage operation: for communications, security, simple laser pointers, etc, etc. 5mW, infrared diode with collimator lens assembly. 780nm (barely visible) $89 .00 Visible laser diodes .......... P.O.A. (expensive) A combined power supply and digital switch kit for laser diodes is available for under ........ $30.00 JUST SEND US AN SAE AND WE WILL SEND YOU A COMPLETE LISTING ON OUR LASER TUBES, LASER DIODES AND ACCESSORIES: AT INCREDIBLE PRICES. CHECK OUT THESE VERY SPECIAL PRICES ON SOME STOCK ANO LIMITED STOCK ITEMS: ....... $19.00 PIN Diodes Very Fast Detectors For Lasers Etc Large IA Detector Diodes ..... . .. . ... $3.50 Lenses For Detector Diodes . $4.30 Mirrors For Deflecting Laser Beams . . $4 .20 X-Y Scanners For Laser Beams . . . $200.00 Photomultiplier Tubes . $199.00 OATLEY ELECTRONICS PO BOX 89, OATLEY, NSW 2223 Telephone: (02) 579 4985 Fax No: (02) 570 7910 Certified p&p $4 -$6 Aust: NZ add $2. Distributors : slightly higher prices may apply. Fig.4: you can use this pattern to etch your own PC board. MELBOURNE: Electronics World - (03) 723 3860 AUGUST 1990 27 ,l\t1 ;AR ;AR ;AR ;AR ,AR cu:e, 1 t1UN IL,.:,.JI\ TL,l\t1 ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELE~T~~ ... -- .. ..M - cLECTR• cLECTRt cLECTR( :LECTR( : LECTR( : LECTRt :LECTR( : LECTRt : LECTRt : LECTR( : LECTR( : LECTRt :LECTRC :LECTRf :LECTR( :LECTRC :LECTRC :LECTRC :LECTRC : LECTRf : LECTRt : LECTRC : LECTR( : LECTRt : LECTRC : LECTRC :LECTR( : LECTR( : LECTR( : LECTR( :LECTRt: :LECTRt: : LECTR t: : LECTRt: :LECTRt: : LECTRt: :LEC:TRt: : LECTRt: :LECTRt: : LECTRt: : LECTRt: :LECTRt: lt~g+=: :.' ,_'. : LECTR•: :LECTR 1: : LECTR1: : LECTR< : LECTR< : LECTRC : LECTR< : LECTR< : LECTR( :LECTR• : LECTR• :LECTR• : LECTR ,LECTR : LECTR• : LECTRo : LECTR • : LECTR• , LECTRo ,LECTR• :LECTR• :LECTR• :LECTR' :LECTR c u:e, 1t1UNIL,~A YL,AK ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR - · - -T~ -· .. -- tLtL, I KU NIG:;JAYGAK ELECTRO NICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR 1:U:C I KONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRON ICSJAYCAR ELECTRONICSJAYCAR ELECTRO NICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR i Frequency Counter, Capacitance 4.5 Digit, Frequency Transistor Test, Capacitance, Meter, Logic Probe, Diode Data Hold, 20 Amp Cat. QM-1560 Tester, $209 10 Amp. 0M-1475 $179 0M-1400 $99.95 Digital Capacitance Meter Ranges 200pf to 20,000uf. 0M-1572 $109.95 ••,.,.,.,.,.,.,.,.,.,.,.,... ,,,.,,,::,:\lj\llllllllllliiiiti::::::•;,,....~~~~::;:..,....~ t~g=: $4~-95 J $3.50 ea 4oograms-ma1<es21i1res Cat NC-4252 t~g=: $7 •95 . .. . -- ,R ,R ,R ,R ,R $8.95 pkt 2 \.::.: y·1e Mounts ~;t~;-~:~~city \jlili! !i~ifv (. ,,,,,, 'l:} ~h r~~~;~~r:roundthecablesandpulledtight :11! Ammonium '~ 'iii.,~ ] $6.50 ea . . · . ·~~ :-. . "' . : . . : · . : .) "D" SIZE Persulphate ....·...-.···.•·.'·.:.·.,. _._ NC-; 4 ELEC. .. - .. ·---· .. - · ... ELECTRONICSJAYCAR ELECTRON ICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ......... .......... ,.. - -- - ... _ .. , _ _ ,, , _,,., ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR :--,,;:"t.L. . _,_.,.;. f 4 tor$12·5D } "C" SIZE ~E iE£~}i::~ ' . : " "' ' 2 :' ~ ~, : .., i ~rif.' $ J -~l,i s,,,.::.. ~=,,. •,.•,., .co,· -•:-mm:e:-m.A!!~. . LECTRt -.- -· 4000 Count, 3.75 Digit, Inductance, Capacitance, Frequency, Temperature, Logic, Peak Hold. ~ii;:::~:~j:~;!~::,:~::,%: m~~}!b:"ii:~=ayba~~ ~P"P • t~g~=: ELECTRON' ELECTRON! ELECTRON! ELECTRON! ELECTRON! ECTRONI 0M-1500 $169.50 ;1§ LECTR( JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR True RMS Autoranger, 3.75 Digit, Frequency, Metex. 1ig~= t,,.'fi~!"'~=2 e=,~=:~=t=i=h=l=o=r=id=e=--·=···=----=--·=--·=----=--·=--·~--,,.,,,::llll/~'·;·~:•;❖•;:·;·;·;;,;,;·;·'·'• :•:•:, .,.,.,.,., t~g~:: ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS ·•--M- -· ----·. --····-·- -·--T--• . -- ··---·- -· -----· - -- ····-·- -· --- -·-- -------· - -· -----·---- -- ---·- -· -----·---- :t~g= : ;': ,.,.;•. LECTR• ELECTRON ICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR Ill 1 Pacet k 2s I ~~~o NOW 9 VOLT - - -- .. ·- .. ·--- · .. - · ... ELECTRONICSJAYCAR ELECTRONI CSJAYCAR ELECTRON ICSJAYCAR ELECTRON ICSJAYCAR ~~c~~ai~i~~~~~~~~ :~~~~reel~~!~ \i:~hey <at>:: m ...,,,••• "' --•-sw ----%•• -~,,,,,,!~-~:.:~- - - - - - . . . ... . . . . .. - --- . .. - .. ·- --· .. - .. . --- - .. ·- · ··- - · .. -· .. . ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCA R ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ---- .. ·-· ·· - - .. _, .. . ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ---- .. ,-.. ,-~,~~ .. ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ~~~~, ..~, .. ~ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS ""'-"" JAYCAR JAYCAR JAYCAR JAYCAR ___ :;TRONIC. ELECTRONIC: ELECTRONIC: ELECTRONIC. ELECTRONIC : tU:G I HONICSJAYGAR : ELECTRONICSJAYGAR , ELECTRONICSJAYCAR , ELECTRONICSJAYCAR , ELECTRONICSJAYCAR , ELEC :LECTI :LECTI :LECTI UCTI 'LECTI UCTi .LECTI :LECTI LECTI LECTI LECTI LEGTI LECTI LECTI UCTI LECTI LECTI LECTI LECTI LECTI LECTI LEGTI LECTI LECTI LECTI LECTI LECTI LECTI LECTI LECTI LECTI LECTI LECTI LECTI LECTI LECTI LECTI LECTI LECTI LECTJ LECTI LECTI LECTI LECTI LECTJ LECTI LECTI LECTJ LECTI LECTI LECTI LECTI LECTI LECTI LECTI ELECTRONICS.JA YCAR ELECTRONICS.JAYCAR ELECTRONICSJAYCAR ELECTRONICS.JA YCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELEGTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICS JAY CAR ELECTRONICS JAY CAR ELECTRONICS JAY CAR ELECTRONICS JAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICS.JAYCAR ELECTRONICS.JAYCAR ELECTRONICSJAYCAR ELECTRONICSJA YCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELEGTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICsJ ELECTRONICSJ, ELECTRONICSJ1 ELECTRONICSJ1 ELECTRONICSJ1 1111111 llll::lljg!;!!fflfflfflfflfflfflfflfflfflfflfflfflfflfflfflfflfflfflfflfflfflfflfflfflfflfflfflfflffl!fflffl!fflfflfflfflfflffll Cat. KA-1652 $369 DC OFFSET KIT FOR DIGITAL Playmaster 60/60 Blue Print MULTI METERS Amplifier Kit Ref: Si licon Chip Aug 1990 This compact unit provides a precise voltage to give a higher resolution of voltage readings from your DMM. Top multimeters, such as the Fluke 85 include this relative measurement feature. Kit includes PCB, box, label and all specified components. e $39":9s HONICSJi Refer EA May-July 1986 Full 60 W RMS per channel stereo Amp for much less money than equivalent commercial units. Refer EA Dec 1989 140W RMS per channel .007% distortion at full power! Full kit. Cat. KA-1725 $599 Screecher Car Alarm Kit Refer Silicon Chip Feb 1988 The car alarm with with the lot. See our catalogue for full details. Refer EA August 1986 The car alarm that goes off 'inside' the vehicle. Full kit including siren. Cat. KA-1675 Cat. KC-5021 $79.50 $34.95 Lead Acid Battery Charger Kit •,•.•, Ref: Silicon Chip March 1990 It will charge both 6 and 12 volt batteries and will charge all of our range from 1.2Ah to 15Ah. It includes PC board and all board compenents. No box or front panel supplied. Transformer not supplied as you have a choice: 1.2Ah • 4.5Ah use MM-2008 (6672) transformer $16.95 / 6Ah • 15Ah use MM-2000 $37.95 Cat. KC-5071 ,,,,,,,,,,,,,,,,, ,,,,,., .... ., ... ..... .. =====8:i8i :~·,IB•wm!wfil• ...m, ... w., ....m, .. ,,:;,i ....czi ... ,:;,i ....czi. $69 t~g;: ■rtt======="""ill'! LECTI LECTI LECTI LECTI LECTI _ECTI _ECTI _ECTI _ECTI _ECTI _ECTI _ECTI _ECTI _ECTI _ECTI _ECTI _ECTI _ECTI _ECTI _ECTI _ECTI .ECTF .ECTF .ECTF .ECTF .ECTf .ECTf .ECTf .ECTf .ECTf .ECTf .Ec:n ECTf ECTf ECTf ECTF ECTF ECTF ECTf ECTF ECTF ECTf Ref: ETI December 1985 This unit is a two transistor two stage transmitter that has the benefits of being VERY COMPACT. The Jaycar kit contains all specified parts and makes an ideal, inexpensive beginners kit. ' --.. Cat. KE-4711 ""\···· $9.95 . : ""' CJ]] ' ~- ' ~- ~ The speaker kit consists of the famous 8' polycone woofer with diecast chassis. The tweeters are the legendary D25. The cabinet is supplied in knock-down form veneered in beautiful black woodgrain finish with silver front baffles. speaker cloth, damping material. grill clips, speaker terminals, screws and parts. The performance of these speckers is outstanding. 'Australian Hi-Fi' magazine recently acclaimed: ·Avery accurate design and exhibits remarkably low levels of colouration and distortion· across the baord." Cabinet size is 338(D) x 290{W) x 680(H)mm. Power handling 70W RMS. Full Kit ;JAY(liiiiiliii••--------------------t... . . . '!"!"--~ ;JAY( ;JAYCAR ;JAYCAR ;JAYCAR ;JAYCAR . Speaker. crossovers. cabinets and all bits ·n· pieces. ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTl10NICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR Refer EA Aug 1989 • Use your IBM compatible computer on your TV . Cat.KA-1720 $39.95 TURNYOUR SURPLUS STOCK INTO CASH!! Jaycar will purchase your surplus stocks of components and equipment, We are continually on the lookout for sour!,:es of prime quality merchandise. CALL MARK HARRIS OR BRUCE ROUTLEY NOW ON (02) 747 2022 . . ----" ,_,.,_~, ' w.. ' ELECTRONICS ELECTRONIC' ·•• - - . , . .~,," AYCAR ELECTRONICSJAYCAR ELECTRONICS ELECTRONIC n t:LECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICS ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICS ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR .: TRONICS, TRONICS, ELECTRONICS, ELECTRONICS, ELECTRONICS, ELECTRONICS, L L L - " , _ , . , - -. . - ~ " L L L V ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR :. rA vrAQ i::1 i:rTQnt-.11r..c :.1AvrAQ i::1 i:r.mnt-..11r..c:.1b. vr.AQ i:-1 i::r.nlnt-.HrQ:_IA vr.AQ i:1 i:-r.TRnt-.llrQ: i:-1 i:-r.mnt-..11r..c:.1Avr.AA i::1 i=rTAnt-.llrQ:_IA vrAA i:1 i=r.TAnNtr..C:. IAVrAJ:? i=r i=r.rnnl\JIC...S.. !A vrAo P CCT 0 O P..II C C i:"::...., Power handling 65W rms • Freq. Resp 34 - 5000Hz Resonant Freq 34Hz • Sensitivity lOOdB ±2dB Magnet weight 20 oz OMS 5.329359 • OES .·.w••••••••••••••••••••• •• •••• • •••••.w•w.w.•.•• • ••.ww•.••••w•.••• ••.-. • ••• •w :::::· 1:1· !~!~ ~ s~t~s~i~ ~ERS { inside of window. Size 72 x 32mm. OTS 1.490212 • VAS 1.086201 Cat CG-2376 NORMAL PRICE $59.50 l~~W~FOR$2 AUGUST SPECIAL $39.50 . .,/)1\. .SAVE $20 , UHF Wireless Security System I Just imagine a security/alarm system that does not need wires to connect the PIRs, window/door reed switches, personal remote control and optional NE j remote keypad. The only wiring required is to connectto a horn speaker. I,,,. UHF 3031\fllz Microprocessor Control Wireless Security Alarm System COMPLETE SYSTEM includes 1 x Control Panel 1 x Passive Infra Red Detector/fransmitter 1 x Door/Window Reed Switch(fransmitter 1 x Hand Held Remote Control/fransmitter 1 x Horn Speaker - 10 watt/wired 1 x 240V AC adaptor 1 x 1.2Ah Back-up Battery 1 x Set of batteries for all transmitters CONCORD VISA HURSTVILLE t w I! t The generation of electricity in modern power stations involves engineering of massive proportions. The power station is a world of its own, vastly different in scale from everything else. The race is on for greater efficiency and minimum costs. By BRYAN MAHER Prior to the early 1950s, Sydney's power stations were built close to the load centres. Predominant loads were the city buildings, electric trams, trains a nd inner suburban homes and industries. The power technology of that time could not transmit large quantities of electricity over great distances. Therefore, power stations at Pyrmont, Ultimo and White Bay were built almost under the shadow of the Harbour Bridge and supplied the city using short 6.6kV and 1 lkV cables . Bunnerong station extended the Sydney County Council's capacity, feeding power to the city and suburbs via llkV and 33kV mains. The sites chosen were close to ample supplies of cooling salt water: Sydney Harbour and Botany Bay. Fuel costs The drawback of these locations was that coal had to be carried by rail over great distances from mines at Lithgow and the Illawarra coast [any coal supplies below Sydney are at great depth - more than 1000 metres down). A similar situation appeared in other Australian cities . Brisbane had power stations built at the intersection of Ann and George Streets in 1899, at William Street in 32 SILICO N CHIP 1912 and New Farm in 1938 - all beside the Brisbane River. Coal was shipped to them by riverboat from Ipswich. In those days, the high cost of electricity was due to: (1). expensive transport of coal; and (2). the low thermal efficiency of boilers and turbines. There had to be a more economical way! The answers came in the development of long distance high voltage power lines, bigger and better boiler/turbo-alternator units, and cheaper and shorter coal transport. Today, very high voltage transmission lines can carry vast amounts of electrical energy far more cheaply than the raw energy in the form of coal can be carried by rail. This statement applies for distances of up to 1000km. The cost per kWh [kilowatt-hour) can be further reduced by using very large boilers, turbines and alternators. The resulting strategy has been to locate large power stations close to the coal mines and to send the generated electricity by overhead lines to the cities, whatever the distance. If a cooling water supply is also available, that's an extra bonus. If not, then a water supply and cooling towers must also be constructed. The thermal efficiency of these heat/steam/mechanical rotational energy conversions is increased by the use of very high steam pressures and temperatures - up to 600°C, which is well above the melting point of many common metals [tin, lead, zinc) and approaching that of magnesium or aluminium! To be economic, such installations must be on a vast scale. For minimum cost per generated kWh, modern power station design therefore favours having just a few very large turbo-alternators, with ratings of between 600MW (600 megawatts) and 1.5GW (1500 megawatts or 1.5 gigawatts) being common. Compared to these figures, older machines seem diminutive. The Ultimo power station had alternators as small as lOMW, while the four 50MW generators installed at Pyrmont in 1952/55 were considered huge in those days. The first Brisbane power station in 1899 was rated at 45kW and the 1912 William Street Plant at 2.5MW, while New Farm in 1928 contained units each rated at l0MW. As Australia grew, newer and bigger power stations were provided. And this trend shows no sign of stopping. Eraring power station When it was completed, Eraring was the largest power station in Australia, generating 2.64GW [gigawatts) of electricity which feeds into the NSW state grid system. Eraring on its own could supply 10 cities the size of Newcas- RIGHT: LOCATED NEAR MUSWELLBROOK in the Upper Hunter Valley of NSW, Bayswater Power Station generates 2.64GW of electricity from four 660MW turbo-generators. Along with Eraring, it is the biggest power station in Australia and uses four huge natural-draught cooling towers to cool recirculated fresh water. ' ' ERARING WAS THE FIRST power station in Australia to be fully equipped with 660MW generating units and, like Bayswater, has a capacity of 2.64GW. This station is situated on the western shore of Lake Macquarie near Newcastle and draws cooling water from the lake. tle, and in 1982 was the first station in NSW to be equipped entirely with 660MW turbo-alternators. Following seven years of planning and construction, generation commenced in March 1982 when the first turbo-alternator set came on line. The second and third units were completed in 1983, with the fourth placed in operation the following year. Eraring is situated on the western shores of Lake Macquarie, a large body of salt water about 28km long and up to 10km wide. Open to the ocean at Swansea, the lake consists of many bays and headlands and has almost 500km of foreshores. Many of Newcastle's suburbs nestle along the shores of this pleasant fishing and boating area. Such a large body of water also provides an excellent cooling supply for the power station's condensers. From Bonnell's Bay, water at 84,000 litres/s is drawn via a 5km long canal to a pumping station. To 34 SILICON CHIP avoid upsetting the local ecology, this inlet water passes under Dora Creek through a 260 metre long concrete tunnel which is 23 metres wide and 4.8 metres high. After being lifted to a high level storage dam, this salt cooling water descends through pipes to the powerhouse, there to be pumped through the condensers associated with each turbine. The cooling water is then returned to Lake Macquarie via a tunnel and canal to Myuna Bay. The immense scale of the cooling system may be judged by the civil engineering effort involved. The inlet canal required a 2,000,000 cubic metre excavation which was then lined with 160,000 tonnes of concrete. The Dora Creek underpass tunnel itself used 16,000 tonnes of concrete. The total canal system, inlet and outlet, runs for nearly 9km. Local mines The site chosen on Lake Macquarie, as well as affording ample cooling water, is situated in the midst of plentiful coal reserves. Myuna and Cooranbong collieries (4.5km and 1.8km distant) are captive mines, specially developed to supply the station. Eraring's total coal usage is 6,500,000 tonnes per year. Coal is delivered from the mines to the power station by conveyor belt. Additional supplies come by road from the nearby Newstand (close to Fassifern) and Awaba mines. By designing larger furnaces and providing appropriate forced and induced draft, power stations can successfully use cheaper low grade coal. This policy has for decades allowed the higher grades of steaming coal to be shipped overseas to produce export income for Australia. Low grade coal with an energy rating 23 . 3MJ/kg (megawattseconds per kg) is supplied to Eraring. Bayswater power station uses coal with an average rating of 22.4MJ/kg. Some coal is treated to remove impurities before use in the power station. In general, in the Newcastle region, the low gr9-de coal comes from shallower mines around Lake Macquarie and in the Muswellbrook area of the Hunter Valley. The higher grade export coal is obtained from very deep pits on the Cessnock field. Environmental impact Despite its enormous size, Eraring station is fairly inconspicuous on the lakeside, largely because it has no cooling towers. The four boiler houses blend with the lake and surrounds and the two slender 200-metre high emission stacks are virtually unnoticeable against a cloudy sky background. Smoke emissions are tightly controlled. The highly successful fabric flue filters trap 30,000 tonnes of fly ash annually. This byproduct is not wasted but is sold for concrete and roadmaking additives. Some key dimensions Eraring's boiler structures are each 80 metres tall. Each of the four turbo-alternators is 50 metres long and weighs 1342 tonnes. They THESE HUGE TRANSFORMERS at Eraring Power Station step up the generator outputs from 23kV to 500kV for transmission to the Kemps Creek Substation. The overall thermal efficiency from coal input to electrical output is 35.4%. WALLERAWANG POWER STATION, west of Lithgow, contains two 500MW turbo-alternators plus two 60MW units (the latter used in mid-winter peak periods) .. A large cooling tower cools the water from the condensers. each stand on a reinforced concrete foundation consisting of 24,000 tonnes of concrete and 1000 tonnes of steel. All four stand in the truly gargantuan turbine hall which is 418 metres long, 27 metres wide and 38 metres high. Approximately 7,400,000 litres of fresh water per day is supplied by Newcastle city for boiler make-up water and sundry purposes. Each of Eraring's four boilers generates 590kg/s of superheated steam at 15,860kPa (2200psi) and 538°C. The alternators, running at 3000rpm, each generate 3-phase 50Hz power at 23kV, 20.71kA, giving 660 megawatts at 0.8 power factor. Eraring's thermal efficiency is quite high, at 37.7% from coal input to alternator output. When the station load is added, the overall efficiency from coal input to station electrical output is slightly less at 35.4%. Tough enough to take it, wherever you take it Fluke 80 Series multimeters come in a rugged, water and dust resistant case. They can handle up to 1000 VAC (RMS)/DC on any terminal and have an "input alert"™ warning if test leads are in the current jacks and a non-current function is selected. They are shielded against electromagnetic interference and are protected against shock and vibration. Each Fluke 80 Series multimeter comes in a rugged pro~ tective holster, with a unique "Flex-Stand"™, which bends and holds to any shape, allowing the multimeter to be stood or hung almost anywhere. To find out just how tough a Fluke 80 Series multimeter can be ... call your local Fluke distributor today. FLUKE AND PHILIPS - THE T & M AL LIANCE ij PHILIPS AUGUST 1990 35 The Story of Electrical Energy - ctd ATMOSPHERIC CONDITIONS are constantly monitored around the Hunter Valley power stations and smoke emissions are tightly controlled. Bayswater power station The success of Eraring, together with the State's increasing demand for electrical energy, lead to the building of an almost identical station at Bayswater in the Upper Hunter River Valley. This was completed in 1986. Bayswater and Eraring now form the backbone of NSW's baseload energy supply and they are presently the two largest power stations in Australia. Coal from dedicated open cut mines at Ravensworth and Swamp Creek is carried by 13km long conveyor belt systems to the power station. Load cells built into certain belt support rollers weigh the coal on-the-run. Deep underground mines at Liddell and Muswellbrook together with open-cut mines at BP Howick, Bayswater-2 and Drayton supply coal by rail and road. Liddell power station Close to Bayswaster is the older Liddell power station. Built in 1971/73, this installation consists of four machines, each rated at 500MW. 36 SILICON CHIP Cooling towers and two fresh water lakes, Lake Plashett and Lake Liddell, provide fresh water coolant for the Liddell and Bayswater stations. Water comes from the Glenbourn dam which is kept filled by 20 gigalitres/year of fresh water pumped from the Barnard River. This water flows via a pipeline and pumping system over the Mt. Royal range into the Hunter River headwaters above Glenbourn Dam, supplementing the upper Hunter's catchment. Both Liddell and Bayswater are fed by conveyor belt from the same, six open-cut coal mines. These are the only NSW power stations receiving coal from open cut operations. The complex conveyor system allows coal to be sent from the mines to the stockpiles at either station. Coal transfer between stations by conveyor is also possible should the need arise. Dirt and impurities are washed out of the coal by washeries before the coal is crushed to the powder required by the station's furnaces. Liddell consumes 2,900,000 ton- nes of coal plus 13,200 tonnes of fuel oil annually. Before Eraring and Bayswater were operational, Liddell power station was the largest in the state, the backbone of the NSW Electricity Commission's generating system. Now it is third in size. Liddell's overall thermal efficiency is 29.1 % . Other lakeside stations Other large stations in the NSW system include Vales Point-B on Lake Macquarie where two 660MW units were installed in 1978/79. Also Munmorah, built in 1967/69 between Lake Munmorah and Lake Budgewoi, features four turbo-generators rated at 300MW each. The older W angi power station is now in dry storage. Wallerawang Wallerawang, west of Lithgow and about 160km from Sydney, is located on the western coalfields. The station consists of three parts. The older A section is now in dry storage as its small 30MW machines are less efficient than the newer additions. The B station has two 60MW units. These are classed as intermediate load plant and used only in mi_d -winter peak periods. The C station, with two 500MW turbo-alternators, was commissioned in 1980. The combined 1 gigawatt output of these machines is an essential component in the state's base load capability. Each 500MW turbo-alternator unit is 48 metres long and weighs 1300 tonnes. This is only fractionally smaller than the 660MW monsters at Eraring and Bayswater. Base load and peak load The six stations we have discussed so far - Eraring, Bayswater, Liddell, Munmorah, Vales Pt and Wallerawang-C are together capable of continuously generating 10.5 gigawatts as long as required. Normal system practice is to have the most economic stations, Bayswater and Eraring, supply the bulk of the continuous load. As domestic, industrial and traction electricity demands vary throughout each day, the other large power stations in the system take up the extra load. By base load we mean the normal electricity demand over a long period, neglecting the twice-daily peaks. Every morning and evening the state uses more electricity as people take showers and prepare meals. This adds considerably to the base load. The minimum power demand typically occurs at around 4am every morning. Included with this article is a On the alert, accurate and safe Fluke 80 Series multimeters come with a large number of "alert" functions designed to ensure safe, easy use. The "Input Alert" prevents accidental damage through wrong lead connection. An automatic power cut-off (after 30 minutes idle) extends battery life. This may be overridden in 36 hour record mode . And the readouts couldn't be easier. Fluke's patented "Touch Hold" ™ feature, when activated, captures, locks and displays each measurement, yet leaves you both hands free to position the probes. In the relative mode, measurements can be made relative to your own reference point Arid there's a maximum/minimum alert, plus automatic storage of max/min readings. And there's much more . Why not be alert to all the special features of Fluke 80 Series multimeters . .. call your local Fluke distributor today. FLUKE AND PHILIPS - THE T & M ALLIANCE MYUNA COLLIERY IS ONE of two specially developed underground mines supplying Eraring Power Station (background). The colliery is 4.5km from Eraring and delivers its output to the station by conveyor. Eraring's total coal usage is 6,500,000 tonnes per year. PHILIPS A UG UST 1990 37 Eraring was supplying exactly 100% of its rated capacity, while Bayswater was at 76%. Notice too that the sharp peaks of 1.3GW around 9am and 6pm were supplied by the Snowy Mountains hydroelectric system, where generators can be started and stopped at short notice. [But that's a story for another chapter). Big British ,b oilers Before closing this chapter, we should have a look at a modern overseas power station, to see how it compares with big Australian power plants. A good example is England's Littlebrook-D power station. Situated on the south bank of the Thames River, this installation features three 660MW oil fired boilers and turbo-alternators. It was built in 1981-2 by NEI (Northern Engineering Industries) Ltd of . Newcastle and the Central Electricity Generating Board (CEGB) of England, and it contributes almost 2GW to the British national grid. Steam at 16,560kPa pressure and 541 °C is generated by boilers which are oil-fired rather than using coal. The boilers are every bit as big as Australian units, containing thousands of tubes made from carbon-chromium-molybdenum steel. These tubes, totalling 480km in length, weigh a total of 6000 tonnes, two-thirds of which hangs suspended from a steel framework extending up to 68 metres high. THE STEAM DRUM for one of the 660MW boilers at Littlebrook Power Station, Englan_d, during construction. The drum is 35 metres long, 2.5 metres in diameter and weighs 250 tonnes. chart showing the winter load used by the whole state of NSW on a particular day (26th June, 1989). Notice the big peak in the morning as people are waking, heating themselves, cooking breakfast and travelling by electric train between 6am and 9am. By that time, industrial and business loads form a steady demand until around 4pm on weekdays. BELOW: THIS CHART shows the total load for NSW on the 26th June, 1989, together with the contribution of each station. Notice the evening and morning peaks and the contribution of the Snowy Mountains hydroelectric stations. Then as evening slides into night, the traction, cooking and heating requirements reach an all-day high, until around 11pm when the general populace tires of TV and goes to bed. Observe the evening peak of 8.943GW - a staggering quantity of electrical power. It is equivalent to the power drawn by almost 9 million lkW single bar radiators. The load chart also shows the contribution of each power station to that particular day's demand. Of this , Bayswater generated 2 gigwatts, Eraring 2.65 gigawatts, Vales Point 1 gigawatt, and Wallerawang and Munmorah 800MW each. That means that 10000 8943 MW' System load B E.C Pumps E3 Snowy [j 9000 8000 7000 SboalhaJ•en 6000 Other 5000 4000 3000 2000 .1000 0200 38 SILICON CHIP 0400 0600 0800 1000 1200 1400 1600 1800 2000 2200 2400 ■ 111, THIS VIEW SHOWS one of the boilers at Littlebrook Power Station (England) during construction. Note the size of the steel girders needed to support the steam drum and the 6000 tonnes of economiser and reheater tubes. The station now contributes 2GW to the British national grid. All the tubes are joined to the steam drum above. Construction involved 70,000 pressure-tight welds of which 10,000 were made on site. Some of the photos in this article show the boiler in various stages of construction. Pre-heating and post-heating was a necessary part of each welding operation. Rigorous quality control, testing and inspection of all welds is necessary for reliability. 100% individual ultrasonic and magnetic particle analysis was used to con. firm that · every weld met the rigorous specifications necessary for long life reliability. During heating from cold to full temperature, the vertical hanging tubes extend their lengths by 225mm due to thermal and pressure expansion. That's a lot of expansion to cope with while still maintaining those extreme steam pressures. Also part of the suspended mass in the boilers are the main steam drums, fabricated from 125mm thick DucoL-W30 carbon manganese steel. Each drum is 35 metres long and 2.5 metres in diameter, and weighs 250 tonnes. Our photo, taken during construction of the boiler, shows the massive proportions and the hanging braces carry- ing the weight of the tubes. Upon completion, the drum, steam tubes and pipes were hydraulically pressure tested, with only 8 leaks being found in the 140,000 welds of two boilers - an excellent result! Each boiler at full load consumes 140 tonnes per hour of heavy residual oil fuel which is delivered by ocean going tankers. Oil firing allows quicker start-up compared with the use of coal. In · other respects, England's Littlebrook-D power station is quite similar to large Australian stations. It too does not need cooling towers, as it is sited right on the river. Acknowledgements Grateful thanks and acknowledgement to ASEA and ABB journals, Electricity Commission of NSW, C. A. Parsons & Co Ltd, Dr Habibulah, Electronics and Power Journal, IEEE, IEE, and NEI Newcastle-Upon-Tyne, for photos, data and permission to publish. Finally, the Electricity Commission of NSW advises that inspection parties are taken on conducted tours of certain power stations. Interested readers should ring the Commission on (049) 73 2933 or (02) 268 6800. ~ Count on them to measure up 1n more ways ■ Fluke multimeters are made in the USA, to the highest standards, offering accuracy you can depend on .. . and they are guaranteed for 3 years by Philips, the name you can trust Each measurement is clearly shown on the display, so you know exactly what you're measuring .. . without having to check connections or switch positions. Fluke Models 83 and 85 have bar graphs for analogue readings, while the Model 87 has a high resolution pointer. The 10-times zoom facility lets you enhance resolution. And your Fluke Multimeter comes comp lete with protective holster, safety leads, 9V battery and operating instructions . To find out why no other multimeter measures up . to the Fluke 80 Series ... ca ll your local Fluke distributor today. FLUKE AND PHILIPS - THE T & M ALLIANCE [e) PHILIPS AUGUST 1990 39 008 33 5757 TOLL FREE MAIL ORDER HOTLINE FOR CREDIT CARD ORDERS! UI AUSTRALIA'S CHEAPEST DISKS .. I 1-9 10+ 1M/B 80 NS $24.95 $22.95 $4.95 $4.50 4164•15 $5.95 $5.50 4164·12 41256-15 $7.50 $7.00 41256-12 $8.50 $8.00 41256·10 $9.50 $9.00 41256-08 S Now you can buy absolute top quality d tsks t hat •r• also the cheapest In Australl■ I They even come with • lffetime warranty, which Indicates the quallty of t hese disks. So why pay 2- 3 t imes the price tor ttM same quality ? PKks of 10, OSI DDwtthout boxes, or brand names but Just the whl1e Jacket and Index label.( S 1/4" disks include wrhe protects.) (ALL PRICES PER 10 DISKS) 1-9 10+ $5.20 $12.50 $12.50 $32.50 $4.90 $4.80 $11 .50 $11.00 $11 .50 $10.75 $29.50 $29.00 CAR ANTENNA BOOSTER · In line instalation · 12V boosts 100% A12073 • •• ••• •••••• •• $ 7.95 50+ 100+ $4.60 $9.80 $9.80 $28.50 500+ $4.50 $9.50 $9.50 $27.50 9MM HOLE, IN3COLOURS 514030 •• Red ..... $ 1 .20 514032 ••Green .. $1 .45 514034 ••Yellow ..$1.45 HEATSINK COMPOUND Heatslnk compound is applied to the base and mounting studs of transistors and diodes. It maintains a positive heatslnk seal that improves heat transfer from the device to the heatsink, thus increasing overall efficiency. H11800 .. 1Og ......$2.00 H11810..1SOg ....$14.95 SUPER HORN TWEETER Requires no crossover and handles up to 100 Watts · Sensitivity: 100dBI 0.5 m · Frequency response : 3kHz-3-0kHz · Independence: 8 ohms. · Size 96 m diameter Normally ..................... $12.95 p ULTRASONIC TRANDUCERS Desi gned to transmit at 40kHz (L 19990) and recieve at 40 kHz (L 19991 )with up to 20V 1/P on the transmitter. These units can't be heard so are ideal for TV remote control's , water level detectors, burglar alarms, motion detectors and information carriers as they can be either pulsed or used in a continuos wave mode. Transmitter L19990............. $4.95 Receiver A13014•••• •••• ••••• $69.95 X15700 ......... $94.95 combinations - Power consumption: · · · · · · 5mA standby, 50 mA alarm Two sector LED and 1 arm LED Wrong number lockout 12V DC operation Relay output Panic button Normally open - Dimmensions: DB25 CONNECTOR SPECIALS P10885 P10890 P10891 P10892 P10894 P10895 P10902 P10905 P10905 DE9S DA15P DA15S DA15C DA15P DA15S 0825C 0B25P 0B25S $1.00 $1.00 $1.00 $1.00 $1.00 $1.00 $1.00 $1.00 $1.00 $ 0.70 $0.70 $0.70 $0.80 $0.80 $0.80 $0.80 $0.80 $0.80 ( CRYSTAL LOCJ~D WIRELESS MICROPHONE & RECIEVER MICROPHONE SPECS: Transmitting Frequency: 37.1MHz Transmitting system : Crystal oscillation . Microphone : Electret condenser Power supply :9V battery Range: 300 feet In open field RECIEVER SPECS: Receiver freq : 37.1 MHz Output level: 37mV(max) Receiving sys: Super crystal oscillation Power sup : 9V battery Volume control: Tuning Led Dimmensions :1 15x32x44mm Weight : 220grams I. • 145 X 100 X 37mm · ACP3 compatible · Over 5,000 possible $37.95 $28.95 $54.50 $20.95 $24.95 $75.95 $25.95 ~ monitoring RS232 interface lead activity Interface powered pocket size for circut testing , monitoring and patching. 10 signal LEOS and 2 spares 24 switches enables you to break out circuts or reconfigure and patch any or all the 24 active positions. SPECS: Connections: OB25 plug on 80mm ribbon cable and OB25 socket Indications: Tricolour Leds for TD RD RTS CTS DSR CD TC RC DTR (E) TC Jumper wires : 20 tinned end pieces Power : interface power Oimmensions: 85 x95 x30m m code 31 /2"SS/DD 3 1/2"DS/DD 31 /2"DS/HD 5 1/4"SS/DD 5 1/4"DS/DD 5·114"DS/4D 5 1/4"DS/HD A10452 ...............$99 A Simple way of · Telephone type digital keypad · Four digit changable (ALL PRICES PER BOX OF 10 DISKS) DESCRIPTION 1·9 BOXES 10+ BOXES L19991 ............ $4.95 RS232 BREAK OUT BOX CODE KEYPAD V These quality 3 level wire wrap sockets are tin-plated phosphor $35.95 $26.95 $51 .50 $18.75 $19.95 $70.95 $24.95 bronze. 1·9 10+ 8 pin 1.50 1.40 14 pin 1.85 1.70 16 pin 1.95 1.80 18 pin 1.95 1.80 20 pin 2.95 2.75 22pin 2.95 2.70 24 pin 3.95 3.50 P10596 28 pin 3.95 3.50 ----- ----- ----~ r~ r?r ONLY ....................$9.95 CHROME LED BEZELS WIRE WRAP IC SOCKETS PANEL METERS GALORE We have a great range of panel meters at great prices! 010500 010502 010504 010510 010518 010520 010525 010530 010533 010535 010538 010540 010550 010560 MU45 0-1m A $12.50 MU45 50/50uA $12.50 MU45 0·100uA $12.50 MU45 0-5A $1 2.50 MU45 0-1 A $1 2.50 MU45 0-1A $12.50 MU45 0-20V $1 2.50 MU52E 0-1A $1 4.50 MU52E 0-5A $14.95 MU45 VUP $14.95 MU65 0-50uA $16.95 MU65 0-1mA $16.95 MU65 0-100uA $1 6.95 MU650-20V $16. 95 MOSFET SPECIALS 2SJ49 2SJ56 2SK134 2SK176 1·9 $7.50 $10.00 $6.90 $9.50 10+ $7.00 $9.50 $6.50 $8.90 ; 115 $265 $395 $295 $395 $495 $695 $795 $895 $1,095 TOGGLE SWITCHES S11010 D.P.D.T $0.90 $0.80 S11020 D.P.D.T $1.10 $1.00 ~I== ~I=== ""I=== QUALITY 3MM LEDS Z10140(R) .... $0.15 $0.12 $0.1 0 Z10141(G) ....$0.20 $0.25 $0.12 Z10143(Y) ....$0.20 $0.15 $0.12 210145(0) ...$0.20 NICADS Save a fortune on expensive throw away batteries with these quality Nicads and Rechargers l Size Oesc . 1-9 10+ 100+ AA 450mAH $2.95 $2.75 $2.50 C 1 2 A H $9.95 $9.50 $8.95 D 1 2 A H $9.95 $9.50 $8.95 $0.15 $0.12 Z10150(R) .... $0.10 $0.09 $0.08 Z10151(G) .... $0.15 $0.12 $0.10 Z10152(Y) .... $0.15 $0.12 $0.10 21 /4" MINI SPEAKERS -----(57MM) With p ins for easy board insertion C10170 third or fifth , then these lnexpenCivedata tranfer will save youthe time and hassle of constantly changing cables and leads around . · No power required · Speed and code tranparent · Two or four position rotary switch on front panel. · Switch comes standard with female connector. RS232· 2 way.. ............ $39 RS232· 4 way ..................... $59 'AS232- X over ........ :..$69 RS232- 2 way auto ............. $69 Centronics- 2 way ..............$49 Centronlcs- 4 way... ...... $69 Centronics- X over ........... $69 Centronlcs- 2 way auto ..... $79 Normally $11 .95 ONLY $9.95 UTILITY BOXES Plastic boxes with alum inium tops and available in four sizes. Very popular for projects and very economical ! H10101 150x90x50mm $3.25 H10102 195x113x60mm $4.50 H10103 130x68x41mm $2.75 H10105 83x54x28mm $1.95 H10110 120x65x38mm $2.95 H10112 120x65x38mm $2.95 (Metal Top) ~~ 9 PIN TO 25 PIN CONNECTOR ADAPTORS The perlect so!ution! Features gold plated pins X1 5668 0B9 Plug to 0B25 Socket X15669 0B9 Socket to 0B25 Plug . 8,ch$8.95 Use these all metal . Piezo tweeters for great top ·end in your band speakers sound system etc. Rated at 30 watts RMS in a systemthey will handle over 100 watts RM$. Two sizes to choose from : Size: 4 " x 10 112·· Independence: Sohms Rating : 30 watts RMS Response : 1.5 kHz - 14 kHz Dimensions: 76 x 1n x 145mm Cat C92084 Normally $49.95 only 39.95 Size: 3" x 7" Independence: 8 ohms Rating 30Watt RMS Response : 2k Hz - 15 kHz Dimensions: 76 x 177 x 145mm Cat C92084 Normally $29.95 only $24.95 ECONOMY TRANSFORMERS QUALITY 5MM LEDS ELECTRIC MIC INSERT If you have 2 or 4 compatable devices that need to share a White durable plastic, 8 ohms Cat. C12010 MIDRANGE HORNS 8087CHIPS 8087•3 (4.TTMHZ) 8087·2 (BMHZ) (10MHZ) 8087•1 (6MHZ) 80287·6 80287-8 (8MHZ) 80287·10 (10MHZ) (12MHZ) 80287· 12 80387•16 (16MHZ) 80387•20 (20MHZ) 80387•25 (25MHZ) DATA TRANSFER SWITCHES 10WHORN SPEAKERS C10610 $ 1.95 $ 1.75 FLASHING LEDS 1·9 2155 240V 6-15V 1A Cat M12155 $9.95 2156 240V 6-15V A2 Cat M12156 $14.95 $13.95 2840 240V 9VCT Cat M12840 $5.95 $4.95 2851 240V 12-6V CT 250mA CatM12851 $5.95 $5.50 2860 240 V 15VCT 250m A Cat M 12860 $5.95 $4.95 6672 240V 15 30vc 1A tapped Cat M16672 $14.95 $13.95 FOLD UP MAGNIFIER An economically priced " hands free" magnifier, lets you take care of all those tricky fine detailed jobs so often encountered in electron ics, or any of many other practical uses such as home , work, hobbies etc . SAVE ENERGY SAVE YOUR PLANET! CARD IN LD! S14049 7W BC ... $34.95 S14051 11W BC .. $34.95 "~ For quality and a great price this EGA video card is the cheapest in the world . Using the most advanced paradise chip technology. it provides reliability and maximum performance. FEATURES INCLUDE: Full compatibility with XT. AT. 386 Full 256K display memory Completely backward comp. with CGA. MDA. and Hercules with intelligent switching software. 480 line extended EGA mode. ONLY ...... $139 THECHEAPESTXT TURBO MOTH ERBOARD IN THE SOLAR SYSTEM '" S14053 12W BC .. $42.95 S14054 18W BC .. $44.95 Why not save money by cutting your energy costs down by 80% ? Each Fluro glob~ produces 5 times the light to the normal globe. So theres no need to buy 100 watt globes when you can by 20 watt globes to replace 100 watt globes. Save money by using power at only 20% of the previous rate. These Fluro globes last at least 8 times as long as the normal globe. 31MHz XT MOTH We are offering to you the FASTEST XT on this Planet. It features 31 MHz compared to 4.77MHz on the standard XT. The board is fully XT compatible and runs with all standard XT cards. Speed is switchable between standard 4.77MHz and turbo speed .. Up to 1 MB of RAM can be fitted on board • For even faster operation the memory above 640K can be used as "shadow" RAM for speeding up BIOS operations or as a RAM disk. The board provides software selection of wait- state. X18036 ... $199 X18036 IBMXT IBM PS2 MODEL 30 10 MHz XT IBMAT t---T-------- --- PC games card for A Switchable with: "UP" for XT "MIDDLE" disabled "DOWN" for AT Comes with 1 game and is .tlesigned for uses 74 ·1 This mighty little XT motherboard has 8 expansion slotsand uses 5 low costing 1MB RAM chips to provide a full 640K memory. The ASIC chip well known for its reliability is also used. The CPU is a state- of the art NEC V20 running at 4.7/ 10 Mhz (switchable) with zero wait states. Size is just 208 X 161mm. "GOOD THINGS COME IN SMALL PACKAGES" DRAM J::,! 424256 X 1 424256 X 2 424256 X 3 424256 x 4 or 421000 x 4 424256 x 5 or 421000 x 4 + 424256 X 1 CAT ..... X18037 The widely acclaimed guide to the IBM pc•s inner workings. The latest edition now covers every model of the IBM micro PC. XT and AT. and every version of DOS from 1.1 to 3.0. B20080 ..................$44.95 · Auto selection and transfer between system, PC mous and Microsoft seri mouse mode. Microsoft serial m · MINI CASE & P.S · 101 KEYBOARD · FDCI HO CARD and mouse syste · · · · compatible. Super high trackin speed : 600mm/ sec Super high resolution: 200 d.p.i (0.12mm/dot) Silicon rubber coated ball Optical rotary encoder )1(19952 .......... $89.00 · 3 button user definable · Silicon coated steel ball ·High resolution movement · Size: 116 X 66 X 34mm Mouse driven software included, allowing you to install with all popular software packages. Also \\._.--::::::-t included is the handy pop up menu softwarethat allows the user to intergrate the mouse with the keyboard, DOS & other popular packages. X19950............. $69.00 · 1 M RAM · G 7 CARO · 1.2M FOO · 12M MB a MOt~ITOR EXTRA a · 360K FDD $995 20 MEG AT 1 •~~~ K~~~~!=; ffl . · FOCI HO CARD l_ _~ : : :lBl EG~ 1 :i~A:~~sAT ~~MR~~ _·_2o_M_ H _D_ __ · 101 KEYBOARD · FOCI HD CARO · 20M HD EGA CARO 1.2M FDD $1 ,295 VGA 20 MEG AT · 20 MEG HD MINI CASE & P.S · 1M RAM 101 KEYBOARD VGA256K CARD FOCI HO CARD 12M MB FOO ~ ., f [ ~ :::lBJ I CIRCUIT ------NOTEBOOK -Interesting circuit ideas which we have checked but not built and tested. Contributions from readers are welcome and will be paid for at standard rates. Electronic time delay switch This circuit will keep a mains light lit for approximately 2 minutes after switch S1 has been pressed and then switch it off automatically. It can be used to replace the mechanical cime delay switches found in hallways or to provide temporary lighting 'for a pathway. The circuit operation is as follows. When switch S1 is pressed, capacitor Cl charges up to the full 15V supply and this turns on the MOSFET transistor Q2. Q2 in turn triggers Triac TRl which is an isolated tab 6A device. Thus, TRl allows current to flow through the lamp (500W max). When the switch is released, Cl discharges via Rl (2.2MO). Eventually, the gate voltage on Q2 falls to a level where Q2 can no longer supply sufficient gate current to AO--~t------4t------------------680!! 1W 02 VNBBAF, BUZ71 D 24DVAC iJ RBLL + - TR1 MAC218A6FP A2 R1 2.2M 500W MAX 0. 47 250VAC 4700 1W fire the Triac and so the lamp is extinguished. The RlCl time constant is about 2 minutes. Transistor Qt is used to fully discharge Cl as soon as the Triac switches off. This prevents the lamp from flickering on and off when the voltage on Cl reaches a critical level. Power for the circuit is derived from the mains via a 0.47 µF 250V AC capacitor & 4700 resistor. Diodes Dl & ZDl rectify the mains waveform to provide a 15V DC supply which is filtered by a lO0µF capacitor. John Clarke, SIIJCON CHIP Effective in-circuit battery tester Most low-voltage battery indicator circuits share a common problem: under unloaded or slightly loaded conditions, the battery basically presents its EMF across the output and that goes low only long after the battery is practically flat. This circuit was designed to give a more effective early warning of the battery condition. It senses the change in the internal resistance RI by comparing the output voltage under loaded and unloaded conditions. Initially, while S1 is open, capacitor Cl charges to the unloaded voltage of the battery. Pressing S 1 now connects a significant load of 1500 across the battery and activates a comparator circuit consisting of transistors Ql & Q2. The loaded 42 SILICON CHIP 1500 0.5W 560r! This circuit provides a good indication of battery condition by comparing the loaded & unloaded output voltages. voltage is then compared to the unloaded voltage and, depending on the relative level, the green, red or both LEDs will glow. VRl is best adjusted by substituting a variable power supply for the battery. To adjust the circuit for a 9V battery, set the supply to 7.5V, press S1 and adjust VRl until the green LED just goes out (red LED on). The circuit has been optimised for 9V 216-type batteries but works well over the 6-12V range. Herb Steinfeld, Glen Waverley, Vic. ($25) Remote control for early Rank Arena TVs About 15,000 years ago, my parents purchased a Rank Arena colour TV. This . TV came with an ultrasonic remote control with three buttons: Volume Up, Volume Down and Channel. Each button causes the transmitter to output a different frequency. After years of faithful service and many minor repairs, the remote control transmitter is now well and truely deceased. Since it is no longer possible to buy a replacement unit, I decided to design a new one. And rather than follow the tuned LC analog approach of the original design, I opted for a robust digital design. The circuit uses two CMOS ICs, thus allowing it to run directly from a small 9V battery. It draws no power unless one of the three buttons is pressed. The design consists of a 4MHz oscillator (ICla) which drives a programmable divider IC2 . The Q and Q-bar outputs of IC2 are then buffered by ICld & ICle, which then drive a standard 40kHz ultrasonic transducer. The positive side of the battery is permanently connected to the circuit while the negative side goes to the · commoned terminals of the three switches (S1-S3). When a switch is pressed, the negative terminal of the battery is connected to + + T 101 9V : 0.1:r 470k ..I.. CHANNEL 1 12 16 2 9 ..ll. A/B L1 L32 L2 40kHz TRANSMITTER UP .E.. OOWNI S2 .,. D6 13 T L16 IC2 MC14557 IC1b ~ 15 l4 4.7M 02(!) 14 LB +9V R3 4C 4049 10pF! 6 5 10pF! 10 B CE 8 01! .,. S1,S2,S3: MOMENTARY CONTACT SPST SWITCH COUNT FREQ. UP/POWER DOWN CHANNEL 45 49 51 43.5 40.0 38.5 circuit ground via Dl, D2 or D3 . Additional diodes [D4-D6) connected to the switches determine the count for the MC14557 programmable divider (IC2). This IC is actually a variable length shift register with its complementary output fed back to its input. To ensure proper operation as a divider, the register must be initially Overvoltage protection for power supplies Many circuits are easily damaged by overvoltage, including high speed CMOS and TTL chips. To protect these ICs from damage, it is often a good idea to provide crowbar protection of the supply in case the recommended supply voltage is exceeded. The circuit uses a single IC and an SCR to monitor the voltage and short out the supply when an overvoltage occurs. Note that the fuse is not necessary for power supplies that are short circuit proof. The fuse should be rated above the normal supply current but must be less than the SCR rating. The C106D1 SCR will handle currents up to 4A. ICl is a Motorola MC3423 which is specifically designed for crowbar applications. The voltage at which it triggers SCRl is set by the ratio of Rl to R2 such that: SPECIFIED FREQ. 43.95kHz 40.0kHz 38 .5kHz cleared. This is accomplished by using a 12okn resistor, a .01µ,F capacitor and inverter IClc to generate a brief reset pulse at switch on. The division ratio is 2 x (count + 1). The counts have been set as shown in the table. Ron Young, Epping, NSW. ($35) 1A + R1 13k 2 3 POWER SUPPLY R2 10k SCR1 C10601 (4A MAX) SENSE1 SENSE2 ICl OUT B MC3423 4 CURRENT SENSE REMOTE 8211 A G TO LOAD VTRIP = VREF(l + R1/R2) where VREF is between 2.45V and 2.75V. The circuit shown is set to trip at 6V and can be Q.Perated from a 5V supply. The circuit will also operate on negative rail supplies. For further information, refer to the Motorola Linear Data Handbook. John Clarke, SILICON CHIP. A UGUST 1990 43 ·------------- . "NEW" 1 IBM*CARDS 1 I AUTOMATIC TELEPHONE I I : ANSWER/ CALL CARD I ...___... I TURN YOUR IBM* PC, XT, AT INTO A I I FULLY FUNCTIONAL ANSWERI NG I I MACHINE!!! II ~~~~~. ~~~~~······· · .......$49 MONO/ COLOU R CARD...$96 MULTI l/O.......................... $99 I . A Sophisticat e d Voice coi l m a i l s y s tem s12K RAM .........................$59 I · A u t o ans wering I Dial~·ng .- ~ ~~= 1 DIAGNOSTIC $750 I ·100 voice ma il boxes I TTLl PRINTER.................. .................. $89 . Password protec tion I I · Message mail i n g I · Auto redialing I .,__111111111_ 1 · Beeperless rem o t e co ntrol I · Toll saver I I . 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X 18156 ..... ..... $275 • 2 -5 Mbps transmission rate • Fully compatible with SMC PC 210 • Bus topology through RG·62 AIU coaxial cable • Zero-Wait al 20 MHz or higher Cat.X18162 .. .. ....... $195 I I I I I I OHcriptlon : / 12.Smhz ayatem ,:;,uck speed I •. 6.25 12mhz veralor,, 80287- 10 CPU I • Socketa for 80287 coproce..or lndependant clock for 80287 I •• Optional Syatema apeed hard-re & aoftware -ciable I•RAM Support• up to 1 MB DIP (8 x 44256 + 4 x 41256) or 4MB SIMM I •• 2RealXTCapacity and 4 AT Compatible Exp-,alon alota time clock/ calender with rechargable battery back- up I •Ouadtel Legal biaa •Sia : 8.75 x 8.75 lnche• Land mart< SI I I Benchmartl teat 15.8 13 12MHz G2 Motherboard without RAM I X183O5 ..................................................................$275 I Include 1 MB RAM with parity I X1831O .................................................................. $449 I 16MHZ O WAIT BABY AT II •8116MHz SyatemUSING G2 CHIPS E T * Clock Speed ~ • 80286-16 CPU \ I •Page Interleave Memory management •Hard-re Implementation of LIM EMS4.0 Socket• for 80287 Coprocesaor I •• Optional Independent Clock for 80287 Coproceuor I • System apeed Hardware & aoftware aelectable • Support• upto 1MB DIP RAM (8 x 44256 +4 x 41256) I or 4MB SIMM RAM I ••2Real XT and 4 AT Compatible Expansion alota time clock/ calendar with Rechargable battery back up I ·• On bo■rd power good generator Sim : 8.75 x 8. 75 lnchea I •Legal blaa Landmark SI I Benchmartl teat 20.8 17.6 I 16 MHz G2 Motherboard without RAM I I X18315 .................................................................$449 I Includes 1 MB RAM with parity I X1832O .................................................................$649 I I I 1 1 16 MHZ O WAIT HALF SIZE AT USING VLSI CH IPSET I •8/ 16 MHz Syatem clock apeed CPU 0/1 wait state RAM Acee.. Selectable I .•• 80286-16 for 80287 coproceaaor I • Sockets Syatem apeed hardware and software aeleciable : I I I up to 1 MB DIP RAM (8x 44256 + 4 x 41256) I I •orSupport• 4 MB SIMM RAM I •• 2RealXT time4clock/ AT Compatible Expansion •Iota • with rechargable battery beck up • I •On board po_, calendar Good generator •Slm:8.75x8.75inchea ~I l •l..egalBIOS Land mart< SI I I Benchmartl teat 21.8 18 1 16MHz VLSI Motherboard without RAM I I X18325 .................................................................$349 I Include 1 MB RAM with' parity I I X1833O ................................................................. $549 and I I I There are different merits for the two 16M Hz I motherboards. The 16MHz G2 motherboards support hardware EMS and later version wlll also support I shadow RAM. The 16 MHz VLSI motherboard can only I support software EMS and do not have shadow RAM, It operates In true zero wait state. Unlike G2 I orbutneat motherboard which operates under page I mode. there Is no need to adjust page sizes In I I I I ■ order to attain maximum speed. --------------- • I .I -.,-...,~...~ . , 'l --; ; - ==<at> ~ v- ,=•~•~q .\l c_ I '" ' / -0 :L ·l l. rn~,,~,~~=:~:!c::~~/ ·!~ ~ , --- AIR IONS GENERATOR No need for air lreshners ~~~e~~;o~~gative Air Ions Just plug it into the cars cigarette lighter and it releases negative air ions into the vehicle ....making a fresh driving environ- ment. Odors , smoke and dust TOUCH MOUSE A STATIONARY BREAK THROUGH!!! Now you can use your fingers instead of your mouse. MODELS: ATM• 110 Touch Mouse for IBM PC/ XT/ AT and compatible·s. Operates under Microsoft / mouse system mode. FEATURES: · User's finger movements on the 58 X 48mm front panel of the touch mouse control the on• screen cursor movement. 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This is a relatively recent model, released a couple of years ago, and the particular set had been in service for only about 6 months - which meant that it was still under warranty. In greater detail, it was one of a ~ batch sold by my dealer colleague ~· to a local motel. He dropped it into ,v.::::;.~~ ~ the shop with the explanation that {~ "It goes for a while and then it loses ~ the picture - the screen just goes black. But the sound is OK". That was a more detailed description than I get from most customers; in many cases, the -OF ~qO-\ \ ~U'R.~e:., ,-r w~s 11-\E: LAS, t"HING :C. TR\~D 46 SILICON CHIP symptoms have to be prised out of them. At the same time, I was a little surprised by it. Usually, a nopicture, no-raster situation suggests failure of the horizontal deflection system, from which most auxiliary voltages - including that for the sound channel - are derived. So I sensed that this was likely to be a "funny" one. Anyway, I set it up in a corner of the bench and let it run. It played perfectly at switch-on and for the next hour or so but then, just as my colleague had said, it switched to the no-picture, no-raster situation but with normal sound. At this stage I hadn't even fished out the service manual and my memory of the chassis - which is used in a number of models - was a bit vague. The last time I worked on one was some years previously, when the chassis first appeared. At this point, it seemed that the easiest thing to do was to take the back off and look for anything obvious. Fortunately, the back forms the larger part of the ea binet and when it is removed, most the boards are readily accessible. I made a careful visual inspection of the boards using a glass to check for dry joints or similar faults but there was nothing obvious. Then I switched it on and, again, there was a perfect picture. I went through the usual bash, wriggle and shake routine to see if I could provoke the fault but it just kept on working. In fact, it kept on working for the rest of the day. And all the next day. And the day after that. So had my prodding and bashing accidently cured the fault? It wasn't a very satisfactory solution if it had, but these things happen. If the worst came to the worst, I could return the set with instructions to bring it back when the fault recurred. I replaced the back and gave it another test run. That lasted about an hour, then it was up to its old tricks; just the sound with a black screen. Well, that changed the whole outlook. It was obviously a temperature sensitive fault which was critical enough to sense the difference between the "back-on" and "back-off" conditions. I put it through this cycle a couple of times and, in the process, learned something else. When it failed it needed to be switched off for only a minute or so for it to recover, after which it would run for another half hour or so before failing . This reminded me of an important feature of this chassis; a very effective protection circuit, designed to sense a number of abnormal conditions and shut the set down. And when this happens, the set will not function again, even if the fault is cleared, until the protection circuit is reset by switching the set off. (I mentioned a similar feature in these notes, involving a National TC2258, back in December 1987; how time flies!). Unfortunately, this can make servicing quite difficult in some circumstances. Is there a fault which is being sensed by the protection circuit? Or is it a typical intermittent, which commonly responds to the off-on cycle anyway? All I could do was press on and hope that more clues would emerge. Since it was necessary to leave the back off in order to work on the chassis, but also necessary to raise the temperature to initiate the fault, I fished out an old blanket I keep for such situations and draped it over the set. That worked fine; I was able to bring up the fault in about half an hour. That was a help but it served to reveal even more about the switch- TV TEST EQUIPMENT (AUSTRALIAN MADE) off/switch-on cycle; switching the set off for only a few seconds was enough to restore performance which only added to the confusion. Up until this point I had been paying more attention to the symptoms than to the manual and the circuit. Now, having established a behavioural pattern, it was time to study the circuit and try to relate the two. My first query was why the sound system continued working when, apparently, the horizontal deflection system was failing. The explanation was simple enough. The sound section, including the sound output IC, is fed from a 12V rail derived from the transformer in the switchmode power supply. This carries an additional winding which, after rectification and preliminary filtering , delivers a bout 17V. This is fed to a 3-terminal regulator which provides the 12V rail. So that was that - the sound system power supply was independent of the horizontal deflection system. That much clarified, it was time to tackle the fault directly. The first check was to determine whether PCB POWER TRANSFORMERS 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 O-5OkV. Can also be switched to check negative voltages. For checking EHT and Focus voltages as well as TVs arid Microwaves. Hi-tension voltages. $89.00 + $5.00 p&p LOW-VOLT AGE PROBE Ideal for checking microwave ovens and TVs. The ~ ranges are from Oto 5kV and from Oto 1 OkV. Double ~ insulated for safety. $79.00 + $5.00 p&p D DEGAUSSING WAND Strong magnetic field, larger than usual coil with multicore centre. Double insulated for safety with momentary switch operation. 24OVA/C 2.2 amps. As important as having a soldering iron! $75.00 + $10.00 p&p Proudly manufactured in Australia by TUNER REPAIRS We repair most tuners on an exchange basis. From only $17 .00 + p&p Cheque, Money Order, Bankcard or MasterCard ,, TUNERS'I V•____ • 216 Canterbury Road, Revesby, NSW 2212 Phone (02) 774 1154 HARBUCH ELECTRONICS Pty Ltd 90 George St., HORNSBY, N.S .W., 2077 Phone (02)476-5854, Fax (02)476-3231 AUGUST 1990 47 ::a ::t: z n n 0 ~ CJ) ~ ""' ~ ,,, 1vwr1 ~ - - ~cl:l! :).l)K. ~ . IS _£° 470 ~ MOAIVEI. 'l!.Q?-,, f~ '"°°" ~""" ~:21' ,.., ,-,o--v-·' - :~i :I[ - ;: ~ ~ ~ ~•\1::·1• U) J Lilli ISO £~~; cso, . ! SC92S- lo ""' c:YOR4M.n R413 1-'« . II 1 ' T;; t --1.'5!0 ._ , ., ~ - • . u ·· ~t -:::z cs.:s .:-sA~ ,. ''"""'!( ) I :-,, j . :81( ! ~~~ ~ I i . - - - -- 1 ; ou, • : j i I C50l ~ =k= ~ ·---=~. r~ ... '"' '·" R674 18.n: •. • r c- 140UUl/ZRIO ~ llo.)K ••• :_C-l401Al 11 ' It,~, ; ! ______, 00~~~!_ ; JS03' Uj ;>:zf ~ f : f',. ~V "~ I ·.;, "~ool " ii I ,~...,.,,. 4,'T,J,. ;U; .~ I ~ ·; . ~~ ~ ~ 2SAll2.l 0521 120 1.670 - ,."' I i;s ,,.. ,... ""' Jlf ! ""'! 1 I ~ I i ~ • I M.U, ~ r:::;' ;Y32\ mm "" E~[§~ 1 7' . ~ -- ID_5tj. IOO : ~ l ~ :1<at>l;~ ~ :, i :I ii ;j ·!j 6 r-- · '1 ,ir-- f~ ' 0521 ir } .,...., ~~ ! "\'t.'51 L:_;_ - .• <at>I :~ ..,,,.'-J" . '- i«~TD 6i _.7 . ~ i :c!,~'®! ';~ ®I - "" ~ , ,. .l. . ~ :o ~ I !~ ~ 470 16V •C6l'l i·z:t 25"13094 . n-,.. ::1 I M.Al61l 06)0 ~tls Fig.1: section of the National TC1480A circuit. The horizontal output stage is at bottom left, the protective circuit to the right of it, and the video/chroma IC at top centre. l pi; 1' I i b i ~~ ,.~KV ~ T i~&p ~e I ,g. ~ - R412 2-21( """'1.01"' ''·""""1 A .... -· l :"" "" 11~ t ~,~ "" ,;J.11 "'" !~ !W ~ ..Rl,,, 4Jf . -j---- -- - - - -- - -- --'~"':_f ...... :.-- , ~ E-BOARD TPN197059AB . .. FOR TC·1401AR TPN197059AA .. . FOR TC·1401MR TPN197059 .. . .. FOR TC·1401ZR VIOEOICHROMA JUNGLE Q630 there was any EHT. Well, there was some, but only a paltry 3kV rather than the 25kV I expected. This was the first real clue. From here I moved back to the collector of the horizontal output transistor, Q501 [lower left of circuit). This should have been showing an output of around 900V p-p . Instead, the CRO showed about 300V. That in itself was not surprising in view of the poor EHT figure, but there was something else wrong. The frequency of this waveform should, of course, be 15,625Hz. In fact, it was more like twice this frequency which was a good enough reason for the poor EHT performance. But why? Back tracking from Q501 takes us to Q502, the horizontal driver transistor, and from there to pin 41 of IC601, the video/chroma jungle chip [top centre of circuit). The waveform here should be a 5.6V p-p square wave at 15,625Hz. In fact, it was well down in amplitude, was nothing like the specified shape, and was also at twice the correct frequency. So, did we have a temperature sensitive fault in the chip? One way to prove this was to to spray it with freezer while in the fault condition. But this was easier said than done. Because of the aforementioned protection circuit, simply spraying the IC and waiting for a result could well be pointless. If the fault had tripped the protection circuit (which seemed likely since the horizontal output stage was involved), any change would not be apparent until the set was switched off and on again. But, as I said, this action might also cure the fault. Then, a possible way out of the impasse presented itself. Continued testing with the blanket in place revealed that, if the set was left on for some time after the fault occurred, so that the chassis became really hot, it might need up to 15 minutes in the off condition before the set would play again. So, after a good long heat soak, I gave the chip a generous spray of freezer, then switched the set off and on again, just long enough to reset the protection circuit had it been activated. Result - a virtually instant response as the tube warm- TETIA TV TIP Hitachi CWP139 (NP6C chassis) Symptom: Set apparently dead . Closer investigation shows that 11 0V rail is OK, as are the 800V screen supply, the 180V video output supply and the EHT. Cure: 1 2V rail missing . In this case there was an almost invisible dry joint at the anode of D705. The configuration of this supply is unusual in that the diode is placed between the earthy end of the supply winding and ground, rather than in the supply rail itself. 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. ed up. Well, it hadn't done that for the previous super heat cycles I had inflicted on it. I reckoned that was it. I had a spare chip on hand and 42 solder-sucked and resoldered pins later it was in place. Brimming with confidence, I then tossed the blanket back over the set and switched it on for a final test. My euphoria lasted exactly half an hour. Suddenly, the set was back in fault condition and I was back to square one. Brain in top gear So where to now? I suppose the shock of the set-back put my brain into top gear, or at least directed it along a different path. I began to think more and more about the protection circuit and the role it had played in that other incident back in December 1987. On that occasion it was the protection circuit itself that was at fault. So was that what was happening here? Had I been chasing a false alarm? One way to clarify this point would be to disable the protection circuit and see what happened. But first, a few points about the protection circuit. It involves four transistors, Q451, Q521, Q503 and Q504 (bottom left of the circuit), plus various diodes, zener diodes and resistors. Just how it senses all the parameters it does - or even how many it senses - is quite complex but the manner in which it shuts down the set is simply explained. The main voltage supply for the video/chroma chip is derived from the 110V HT rail via a 6.8k0 resistor (R519}. This applies 8.5V to pin 42. And pin 42 is also connected to the emitter of Q503 via a 560 resistor, R536. Q503 is normally turned off but when a fault is sensed, it turns on and this pulls down pin 42, reducing its voltage to a small fraction of its normal value. This shuts down the most vulnerable parts of the set. It was now fairly obvious that what I had taken to be a fault in the chip was really the result of the protection circuit doing its thing. To disable this circuit, I had only to lift the 560 resistor. But it wasn't quite as simple as that. If there really was a fault, there was a very real risk of an expensive component being destroyed before I could hit the power switch. But that was a risk I had to take. To reduce this risk as much as possible, I set up a meter to monitor the HT rail and the CRO to monitor the waveform out of the horizontal output transistor. Then I tossed the blanket over the set, switched it on, and waited. And I waited. After about two hours, with the set still playing, I was ready to believe that the protection circuit was the culprit. Then suddenly there was no picture. My gaze flashed first to the meter, then to the CRO. But neither had changed. And a further check confirmed that the EHT was normal. I checked the picture tube G2 voltage, the value of which is not given on the circuit. It was at something over 400V which I was happy to accept. I then checked the voltages on the collectors of the R, G, B driver transistors but all were normal. It was all becoming very disconcerting because I was now rapidly running out of ideas. As far as I could see, all the picture tube operating voltages were correct, yet the set just wouldn't work. It was almost as though the electrons had gone on strike. At a more rational level I reasonAUGUST 1990 49 SERVICEMAN'S LOG -CTD 1lrd £.1-E:C...--rR ONS ON ST'R \ Ke A, 1"H €" PI C..-TORE: "TV~E: H~-re::R c...tRC.U ed that there was only one thing I hadn't checked - the picture tube heater circuit (lower right of the circuit). There isn't much to this; the winding on the horizontal transformer, a 30 resistor (R523), a plug and socket, and the tube heater. I checked all these with the ohmmeter and all were OK. But there had to be something wrong and I wanted to make a visual check of the heater . Unfortunately, the physical layout makes this difficult unless one knows exactly where to look. I switched the set on again, switched off the lights, pulled down the blinds, and confirmed that the heater could be seen. But it could only just be seen and then at a fairly critical viewing angle. I restored normal lighting and let the set run. When it failed I darkened the room again and took a careful look. Result - no heater. The culprit - at last! So I was on the track at last. But was it the tube, or the resistor, or 50 SILICON CHIP l'r... the transformer? About the only way to determine this was to measure the heater voltage; something that needs a special meter because the supply is at horizontal deflection frequency. Fortunately, my Fluke 87 meter will handle this with ease and that was the answer; there was no heater voltage. Well, that cleared the tube which was a relief - and put suspicion squarely on the transformer. But I wanted to be sure before I pulled the transformer out and replaced it. What was needed was a continuity test but, from observations thus far, this would be valid only when the system had been heated to the point of failure - and it would have to be done smartly. I disconnected the lead from the 30 resistor and restored the connection with a clip lead. I set up a meter for resistance measurement, connected one lead to the other end of the winding (pin 8), switched the set on and let it run until it failed and then for a while longer to make sure it was really hot. Then I switched the set off and quickly changed the clip lead connection to put the meter across the winding. Result; open circuit. But I continued to check the meter and, within 20 seconds or so, it dropped to zero ohms. That clinched it of course but I had to order a replacement transformer. When this arrived, I fitted it and gave the set a thorough workout. It behaved perfectly, even with both the blanket and the cabinet back in place. OK, so why did the failure in the heater winding trigger the protection circuit? The answer is that this heater voltage, via diode D523 & filter capacitor C582, provides a DC voltage to the protection circuit. Presumably, this is . designed to monitor the whole horizontal output circuit but it was tricked by the winding failure. The protection circuit also monitors a 25V rail which is derived from pin 6 of the horizontal transformer. This rail also supplies the vertical output chip (IC401, pin 7) via a 1.50 resistor (R411), one end of which goes to the emitter of Q451. Apparently, this arrangement is designed to sense any excessive current drawn by IC401. The 110V HT rail is apparently monitored by Q521. But why did the set take so much longer to fail after the protection circuit was disabled? This is a real puzzle and the only theory I can advance is that the winding failure was not sudden. Instead, there was probably an increase in resistance initially. As a result, the heater voltage may have been reduced enough to trigger the protection circuit but not enough to seriously impair tube performance. But that is only a theory. And that's about as far as I have been able to work things out so far so it will have to suffice for the present. But about that heading; perhaps it should have read " ... the last thing left to try". Who done it? And now, for a complete change of pace, here is a short story without any serious technical aggravation. The main point of the story is: "Who done it?". It concerns a Sharp colour set, model 9C143, a set that has been around for about 10 years. The owner, a new customer, simply dumped it on the counter, said "It doesn't go", and wanted a quote to fix it. I'm not into quoting in the normal sense. It's a risky business. By the time you've found out what is needed, most of the hard work has been done, with the real risk that the customer will shake his head, say "Too dear" and walk out. But, not wishing to come on too strong with a new customer, and because it involved a total failure, I said I would have a quick look at it and try to get some idea of what was involved. If it was easy to diagnose that would be fine but beyond that I wouldn't commit myself. After a moment's hesitation, he accepted the offer. When I pulled the back off the set, the first thing I checked was the mains fuse. It was open circuit; not blackened or even visibly faulty, but open circuit nevertheless. Whenever I find an open circuit fuse, the next thing I suspect is the degauss circuit. A common fault is a short-circuited thermistor, although the fuse reaction is usually more violent. · So a typical routine is to unplug the degauss circuit, fit another fuse , switch on and watch what happens. If the fault is elswhere in the set, the fuse reaction can often reveal a lot about it. As an added precaution, I usually fit a lighter fuse than the one prescribed, since it no longer needs to survive the degauss surge. But in this case someone had been there before me; the degauss circuit was already unplugged and, what was more, the plug had been neatly taped to the winding, well out of sight. OK, why had the fuse failed? The prescibed fuse is a 2A delay type, so I fitted a 1.5A quick blow type and switched on. Nothing happened; nothing untoward, that is. The set came to life immediately and produced a first class picture. And strangely, there appeared to be no purity error. I let it run for a while, then checked the degauss thermistor. And, of course, it was shorted so that was easily fixed. I then refitted the degauss plug, changed the fuse to a 2A delay type as prescribed, and tried again. And again, the set worked perfectly. I let it run for the rest of the day but there was no sign of trouble. So why had the original fuse failed while the degauss circuit was unplugged? A closer look at it pro- vided the clue; it wasn't the prescibed type but a 1.5A quick blow type, similar to the one I had used experimentally. Well, I reckoned that was pushing things a bit. Such a rating is OK on a short term basis but is almost certainly too light for continuous use, even with the degauss circuit unplugged. On that basis, I felt confident that the set could be safely returned to the customer. But what was the history of all this and "Who did it"? I hate to say this but I suspect that it was a professional serviceman. Granted, it could have been a do-ityourself type but, if so, would they have thought to fit a lighter fuse? And would they have bothered to tape the plug out of sight, as if to hide what had been done? I doubt it. I fear it was one our own kind who simply couldn't be bothered doing the job properly and took the easy way out. If so, I would nominate him for the Striped Apron Award for the year. Of course, I quizzed the owner as discreetly as I could but it was obvious that he couldn't (or didn't want to) help. So I backed off and that means we shall never know what really happened. But we can do without "servicemen" like that. 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 Price: $All.95 plus $3 p&p each (NZ p&p $A6). Send your order to SILICON CHIP Publications Pty Ltd, PO Box 139, Collaroy Beach, NSW 2097 (use the handy form on page 112). Fax 979 6503. AUGUST 1990 51 Digital Sine/Square Wave Generator; Pl.2 This month we present the constructional details on our new Sine/Square Wave Generator. The parts are all installed on two PC boards which are soldered together at right angles and mounted in a plastic instrument case. By JOHN CLARKE Very little point to point wiring is used in this project as it is virtually all on the two printed circuit boards. What little wiring there is, is mostly associated with the mains transformer. The two printed boards occupy just about all the floor space inside the standard instrument case which measures 263 x 190 x 84mm. The main board measures 225 x 162mm and it has the power transformer mounted directly on it, which does away with the need for a separate transformer baseplate. The front panel is made from a sheet of red Perspex measuring 250 x 75mm, the lower half of which is covered with a Dynamark label. We expect that kitsets will be supplied with screen printed red Perspex front panels. Behind the Perspex front panel is a black plastic film which masks all but the four digit The main regulator (REG2) is mounted on a U-shaped heatsink which is bolted lo the PC board. Notice how the plastic insulating sleeving fitted over the power switch leads is extended back past the heatsink. 52 SILICON CHIP displays so that components on the display board are not visible. The display PCB measures 227 x 75mm and is mounted at rightangles to the main board. The complete 2-board assembly is secured into the case by four selftapping screws which thread into integral pilla rs in the base. The vertical display board is held rigid by slots in the front of the case, along with the red Perspex panel. Board assembly Before you start work on the boards, check them carefully for any open circuit or short circuited tracks by comparing them with the PC artworks included in this article. Also check for any undrilled component holes - it is a pest to have to drill holes in a partly assembled board. Note that three of the tracks on the display board around S1 and S2 are open circuit at one end. This is not a mistake - these tracks are there to provide shielding We suggest you start work on the main board first. There are a large number of links on the board and these should be installed first. Many assembled kit boards we see don't look good because the links are all untidy and crooked. The way to make them look good is to take a length of the tinned copper wire and straighten it by putting one end in a vyce and pulling the other end with a pair of pliers to stretch it slightly. You can then take this length of nice straight wire and cut it to length for each link. The ends of each link should be neatly bent with pliers so that they fit into position nicely on the board. A little care in this aspect can help make your boards look a lot better. Incidentally, some people may question why we have produced a board with a relatively large number of links. Why not go to a REAR PANEL CORO GRIP - - ~/G~~IT \ ACTIVE (BROWN) HEAT SHRINK TUBING ""',1 I I I I • 1% double sided board and eliminate them entirely? That could be dohe but it would be a good deal more expensive and make no difference at all to the final result. Double sided boards are a good idea for mass produced gear where labour costs must be kept low but for this project they would be a waste of money. The four PC stakes are optional but should be installed now if you intend to use them. There are three in the power supply section of the board and one near IC7. The resistors can now be installed. Note that all of the resistors shown with a star in the circuit presented last month and the wiring diagram of Fig.5 are 1 % types. The 5-band colour coding for these can be difficult to decipher. To help \ FRONT PANEL t NPO SEE TEXT Fig.5: here's how to install the parts on the main PCB. Be sure to use 1% resistors where indicated and take care with component polarity. All wiring to the mains switch & to the power transformer must be run using 240V AC cable. Note the wire link under VR3. in this regard, we have included a table of the all resistor codes but if you are not sure about any resistor value, check it with your multimeter before installing it. Now the ICs can be installed and when they are all in, the board will look more than half complete. Don't hurry the job though, as you could make mistakes. Make sure that all the ICs are placed in the correct position and oriented correctly they all face the same way except for IC2, the 74HC42. Note that the parts list and circuit diagram presented last month give a choice of 74LS (low power Schottky TTL) or 74HC (high speed CMOS) for a number of the ICs. The only other permissible IC substitution is to use a TL071 instead of an LF351 for IC5 . Now install the diodes and transistors, making sure that each is correctly oriented. The capacitors and trimpots can then be added, again making sure that the electros are correctly polarised. Cut the shafts of the two dualgang potentiometers (VR2 & VR3) to a length of 29mm. They are soldered directly into the board although note that you might have to make some fine adjustments to AUGUST 1990 53 Cut the shafts of the switches and the single gang pot to 13mm before mounting them on the display PCB. The pot is mounted on three PC stakes. them later when the time comes to mate the two boards together. Regulators REGl and REG3 (at the back of the board) are installed upright, while the main regulator, REG2, is mounted horizontally on a U-shaped heatsink. Apply a smear of heatsink compound between the regulator base and the heatsink to improve the heat transfer. Both the regulator and heatsink are secured to the PCB using a machine screw and nut. Display board Work can now begin on the display PCB. First, install the PC stakes, noting that the PC stake marked A should be installed from the copper side of the PCB. Note that there are three stakes for the connections to the single gang pot, VR5. The links and all the resistors can now be installed. The displays are mounted onto Molex pins so that they are raised from the PCB by about 4mm, to be closer to the Perspex panel. The transistors, trimpots and capacitors go in next, followed by the rotary switches and the single gang pot, VR5. The rotary switches and the single gang pot should have their shafts cut to 13mm before they are soldered to the board. RESISTOR CODES D D D D D D D D D D D D D D D D D D D 54 No 1 1 1 1 2 1 2 3 8 3 1 1 9 2 SILICON CHIP Value 330k0 1% 270k0 1% 120k0 1% 82k0 1 % . 47k0 1% 39k0 1% 33k0 1% 22k0 1% 20k0 1% 18k0 1% 15k0 1% 10k0 1% 10k0 4 .7k0 2.2k0 2700 470 330 4-Band Code (5%) not applicable not applicable not applicable not applicable not applicable not applicable not applicable not applicable not applicable not applicable not applicable not applicable brown black orange gold yellow violet red gold red red red gold red violet brown gold yellow violet black gold orange orange black gold 5-Band Code (1%) orange orange black orange brown red violet black orange brown brown red black orange brown grey red black red brown yellow violet black red brown orange white black red brown orange orange black red brown red red black red brown red black black red brown brown grey black red brown brown green black red brown brown black black red brown brown black black red brown yellow violet black brown brown red red black brown brown red violet black black brown yellow violet black gold brown orange orange black gold brown Finally, the DPDT switch (S3) can be installed. Mating the boards The display PCB is joined to the main PCB by soldering the underside of the main PCB bus to the display bus. The first step in this process is to fit the display board over the shafts of the two ganged pots, VR2 & VR3, and secure it with lock washers and nuts. Now ensure that the PCBs are square and that the bus pattern on the main PCB lines up with the bus pattern on the display board. Tack solder the boards together at several points along the mating bus patterns and then test the boards for fit in the case. Do the same check with the front panel fitted (we're assuming here that the front panel is finished and ready to fit) to make sure that everything lines up in the case. Finally, solder the two PCBs together. The wiring can now be completed. A short wire runs from the Fig.6: install the wire links and PC stakes on the display PCB first, before mounting the other components. The PC stake at point A is installed from the copper side of the board. Point B on the earth pattern is wired to the bodies of the rotary pots (see photo). "A" PC stake on the main PCB to the corresponding "A" stake on the display PCB. Solder wires from the VR2 & VR3 pot bodies to the B track on the display PCB. This earths the bodies of these pots. Transformer wiring The transformer is mounted on the main PCB as shown in Fig.5 . You will need to run hookup wire from the OV, 7.5V and 15V AC secondary connections on the transformer to the three PC stakes on the main board. If you are working from scratch and not from a kit you will need to drill and file a hole in the rear panel of the case to accept a cordgrip grommet. This is to anchor the mains cord. We suggest you use a 3-core flex which comes with a moulded 3-pin plug. Fit the cord and check that it is held securely by the cordgrip grom- Right: here's how to mount the single gang pot. Bend the pot terminals so that they fit over the PC stakes and make sure that the pot body sits flush against the PCB. CAPACITOR CODES □ □ □ □ □ □ □ □ Value AH Value IEC Code Ell Code 0.1uF .022uF 220pF 100pF 22pF 12pF 10pF 100nF 22nF 100n 22n 220p 100p 22p 12p 10p 104 223 221 101 22 12 10 met. The Earth lead of the mains connects to a solder lug which is secured by one of the transformer mounting screws. The Neutral wire goes directly to one of the transformer primary connections while the Active wire goes to the power switch on the front panel. Don't connect it to the switch at this stage though because you need to go through a test procedure before final assembly. Instead, connect the mains Active wire to the other primary terminal of the transformer. Fit heatshrink sleeving over the two primary terminals or tape them up so that there is no chance of accidental contact. If not supplied ready made in the kit, the Perspex front panel can be cut to size and drilled for the switches, pots and BNC output socket. To do this, first attach the Dynamark label, then punch out or cut out the holes in the front panel. GO ~ r,~ -=-=~--==i ~~ 4..'o":::::~ ~ ~ ~~ °°" I .Rd m'IIII 56 SILICO N CHIP 7 I- • ::) 11. I::) 0 UJ er: I N • < ::::) N J: J: .ll: ~ 0 0 (/) oO ,... • eo J: ' N O.ll: ,-o UJ z 0 u, en N J: .";° 0 N ~ J: Oo • g C a, .0 . . 00 0 ,...' N ,- :5 6 ,... 0 0 ,- ,... "-I" • 0 (.) Cl') UJ z u.. I(/) ::::) -, C < > (.) zUJ ::::) UJ • (/) er: < 0 UJ er: u.. 0 (.) a: Figs.7-10: here are actual size artworks for the two PC boards, the front panel and the light mask. • UJ 3: ~ VOLTAGE TABLE The four 7-segment LED displays are mounted using Molex pins so that they sit close to the front panel. Be sure to install each display with its decimal point at lower right. IC1 IC2 IC3 IC3 IC4 IC4 IC5 IC5 IC6 IC? ICB IC9 IC10 IC11 IC12 Q1 Q2 pins 11, 16 pin 16 pin 7 pin 4 pins 7,8, 12 pins 6, 1 3, 1 4 pin 7 pin 4 pins 6,10,14 pin 14 pin 16 pins 2, 1 o, 1 6 pins 4, 11, 1 6 pin 14 pin 18 collector collector +5V +5V +10V -10V +5V -5V +10V -10V +5V +5V +5V +5V +5V +5V +5V +10V -10V do not read waveforms much beyond lkHz. If there are problems, check the component overlay against your circuit for incorrectly placed components and for short circuits beneath the PCB. In our experience, most problems in kits of this sort are due to soldering and little else. Setting up Solder tack the two boards together in a couple of places and test the assembly in the case before soldering all the edge connector pads. Make sure that you don't create shorts between adjacent pads. The masking film is installed directly behind the Perspex panel and will also require matching holes for the switches and pots. Test the front panel for fit in the case [see above) but do not fit it to the board assembly yet since it will interfere with the trimpot adjustments required for the setting up procedure. Power up Before switching on, check the mains wiring carefully. When you are satisfied that everything is correct, switch on and check that the 58 SILICON CI-IIP power supply voltages on each IC are correct. This should be + 5V for all ICs except for IC3 & IC5 which have a + 10V supply. You should also check the - 5V supply to IC4. Most of the relevant voltages are shown in the accompanying table. The display will also be lit if all is well. If the circuit checks out so far, check that there is an output on both sine wave and square wave using either an oscilloscope or multimeter set to read AC volts. Note that many digital multimeters There are three setting up procedures required for the generator. You will need a multimeter and frequency meter. As an alternative, an oscilloscope can be used although its accuracy will be limited if used for the frequency adjustments. The first operation is to set the offset voltage at the output of the generator when it is in the sinewave mode. This is done by measuring the DC level of the sinewave when set to about lkHz. At this stage, the output frequency shown on the display will not be accurate but this is not important for this procedure. Set your multimeter to a low DC voltage scale and measure the voltage at the wiper (2700 resistor) of VR5 (the output level control). Now adjust VRl for a minimum DC reading on the multimeter. You should be able to set VR 1 for a reading of less than 50mV DC the closer to OV, the better. The se_cond procedure is to accurately set the frequency display FOR FAST SERVICE-CALL_TECH-FASTFIRST! 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Full range of Fluke Accessories. Fluke made in U.S.A. t1:1c:r'l-:Fzsl' T & M PTY. LTD. VISA Call Tim Wortman the specialist Fluke Distributor TECH-FAST T & M PTY. LTD. 14B MAXWELL STREET. TURRAMURRA N .S.W. 2074 TELEPHONE: 988 3865 FAX: 988 3861 This view shows how the metal bodies of the dual gang pots are connected to earth (point B) on the display PCB. Also shown in the lead that connects from point A on the display board to point A on the main board. why not go for the maximum frequency possible? The reason that 500kHz should be the maximum obtainable frequency is because this gives the best possible hash reduction with the tracking filter, which operates in tandem with the coarse and fine frequency controls. If you have to change the value of the lOpF capacitor, increase its value to reduce the maximum possible frequency and reduce its value to increase the frequency. Note that there is space on the PCB to add a parallel capacitor if necessary. Now select the 1-lOOkHz range with switch S2 and the O.lHzlOOkHz range with Sl. Check the maximum frequency obtainable with the coarse and fine frequency controls set fully anticlockwise. Adjust VR4 until the output frequency approaches lOOkHz. If VR4 needs to be adjusted almost fully anticlockwise, the 22pF capacitor will have to be increased in value. If the frequency cannot be set close to lOOkHz, the 2 2pF capacitor have to be reduced. In the final result, you should be able to adjust VR4 so that the frequency range is slightly beyond lOOkHz. This will allow some overlap between ranges. Note that there will be some interaction between all these adjustments and so you may have to repeat them to get the final result. Final assembly The two transformer mounting nuts should be soldered to the copper pattern of the main board to ensure a good earth connection. meter. VR6 adjusts the O. lHzlOOkHz range readings, while VR7 adjusts the 100-500kHz range. Connect a frequency meter or oscilloscope of known accuracy to the output of the generator and select the 0. lHz-lOOkHz range. Set the output to a high frequency, say 90kHz, and adjust trimpot VR6 so that the frequency display reads the same as the external meter. Similarly, select the 100-500kHz range and set the output to a high frequency, say 450kHz. Adjust trimpot VR7 for the same reading on the frequency display as on the external meter. 60 SILICO N CHIP Finally, the overall frequency range of the generator needs to be set. Select the 100-500kHz range and determine the maximum frequency you can obtain from the generator with VR4 set to about half way. This frequency should be about 500kHz. If this frequency is reached well before the coarse and fine frequency adjust pots have reached their full travel or does not reach anywhere near this figure , then the lOpF capacitor at pin 3 of IC7b will require changing. If you are obtaining a frequency well in excess of 500kHz, you may think you have a bonus. After all, Now the front panel can be installed. Before you do that though, fit the BNC socket which is retained with a single nut. Don't forget the earth lug for the BNC socket - it fits under the retaining nut. Make the connections to the BNC socket with two short pieces of the hookup wire, then fit the front panel and the light mask to the display PCB. Secure the panel by fitting the nuts and lockwashers to the switches. Now you need to wire the mains switch. The Active wire from the mains cord goes to one side of the switch while the other side goes the transformer primary. Fit heatshrink tubing over the switch to make the mains connections safe from accidental contact. Finally, fit the lid onto the case and you are finished. ~ Attention ALL constructors, hobbyists and users of rack hardware. Manufacturer makes maior BOO BOO with huge shipment of rack cabinets. Massive ~ savings of 40% and These are actual cases from our latest delivery of the famous Altronics rack case. They look fine don't they? Well then, what's the problem you ask? Why are they selling so cheap? • Firstly, the front panels were specified to be anodised. Instead, the maker has black powder-coated models H 0411, H 0412 and H 0413 and silver alumadised the "natural" models, H 0401, H 0402 and H 0403. The actual appearance and finish is to a high standard and attractive. So what's the problem? Very simply, the majority of these rack cases are sold by our parent company , Altronic Distributors, to manufacturers and most manufacturers require (and insist on) an anodised finish to match with associated equipment when assembling rack consoles. Sale Model H 0401 H 0402 H 0403 H 0411 H 0412 H 0413 Finish Natural Natural Natural Black Black Black Normally $59.95 $79.95 $89.95 $59.95 $79.95 $89.95 1-5 $39.95 $49.95 $59.95 $39.95 $49.95 $59.95 6+ $35.00 $45.00 $55.00 $35.00 $45.00 $55.00 • Secondly, the lid securing screws don't always line up perfectly - you occasionally might need to drill out a hole or two to get the screws to fit 100%. • In our view these deficiencies will not bother the average enthusiast (and perhaps quite a few trade users) and more than made up for with these fantastic savings. Once they're gone - that's it. Obviously we can't take any back orders in this instance. NEW! NEW! NEW! Another superlative design from the Silicon Chip design team. See Silicon Chip Magazine July '90 The use of modern circuit technology Waveform Synthesis enables this Generator to deliver . performance specifications comparable to commercial equipment costing $2000 and more. ! 'I\ This new Digital Sine/Square Wave Generator uses high speed CMOS ICs and a digltal filter IC to produce sine and square waves over the frequency range from 1 0.1 Hz to 500Hz. It also features a 4-digit frequency readout and an output level control. r K2547 i Specifications: Frequency range: 0.1Hz-500kHz in four ranges; 0.1-10Hz; 10- $175.00 VALUE 1000Hz; 1-100kHz; & 100-S00kHz • Output wave forms: Sine and square • Harmonicdiatortion: Less than 0.15 from 0.1Hz-50kHz; 0.27% at B0kHz • Square wave rise time: 10ns • Square wave fall time: 10ns • Output level: Sine wave; variable from 0-1.2V RMS; Square wave; variable from 0.5V p-p • Output impedance: soon nominal• Load impedance; soon to infin~y •Protection: Short circu~ protected (indefinite)• Display accuracy: +/-2% +1digit How many timea have you opened up that favourite board game to find that someone has pinched the dice? In that case, why not build this elegant electronic dice which uses just two CMOS ICs? It simulates the roll of a rea l d ice and even turns itself off. 4 separate channels-up to 30 seconds per channel record/playback time. Build this elegant without one single moving part/ Electronic Dice LED readout simulates a "dice" - Great fun to build. see Silicon Chip July 90. Thia Digital Recorder delivers sstonishing reproduction of voice and/or music Digital (X ,, c9ni~i, DeR ec o r d e r Build this for the kids! $ 29 •5 0 Includes Jiffy box. The specificationa ofthia excellent design compare w,ry favourably with commercial test equipment costing $300 and more. A w,ry worthwhile addition to your workbench. Digital Capacitance Meter "Silicon Chip" May '90 Superb test equipment. K 2524 Here is a digital voice recorder that can store 4 different signals, voice, sound or a music source of up to 30 seconds each or one recording of up to 2 minutes. There are 4 trigger inputs so that a message can be retrieved when a certain condition occurs. Battery backup is provided so that the messages are retained when main power is off. Typical applications include: • Alarm system messages • Sales messages for customers put "on hold" • Experimental telephone answering machine• Door station announcer• Talking displays for shops • Emergency warning message announcement • Operation instructor for machinery etc.• Countless other applications where voice or music is required • $1 OO's cheaper than imported digital recorders K 9550 Kit complete- PCB Format .K 9555 Kit complete - with Inst. case $120.oo • Capacitance lpF to 9999µF in seven ranges •Accuracy+/. 1%, +/- 1 digit • Mains powered • Designed for laboratory and wmkshop use HERE YOU ARE BARGAIN HUNTERS! Digital Capacitance Meter (See EA Aug 85) -- -- $129.00 For those who want a professional appearance • s_ tand alone product, we can supply with our Deluxe H 0483 Instrument case and fully punched and screen printed front panel $149.00 Laboratory Power Supply Kit Over 500 sold to date ! EA May '85 M e a sure l pf to 99.9 9µ.F d that's how long our K 2522 Dignal we have to make room for the new at we have left for an incredible el • 3 to 50Volts at 5Amps • Single PCB - very easy to build • Floating output • Super low ripple voltage • High efficiency TOROID transformer is used K 3301 10 turn 0/P control $29.50 $14.50 K 3302 +/-12V Aux. outputs For the engineer and hobbyist 40MHz Dual Trace Oscilloscope • CRT Display 150mm rectangular, domed mesh and 12kV post accelerator type. e Vertical Amplifier (CH1 and CH2 identical) Operational Modes: CH1, CH2, ADD, DUAL, ALT, CHOP Sensitivity: 5mV- 5V/Div 3% in 1-2-5 steps, 1mV- 1V/Div 5% X5 Mag • Horizontal Amplifier Operating Modes: X-Y operation CH1-X axis, CH-2 Y axis Sens~iv~y: 5mV - 5V/Div +/- 3% in 1-2-5 steps Input Impedance: 1MOhm +/- 2%, 25pF +/- 3% e Time Base Sweep Method: AUTO, NORM, SINGLE Magnified Sweep: 10 times+/- 5%, Max 20nS Delay Method: Continuous delay and adjustment e Synchronization A, 8, 8 Triggered, Internal V-MODE, CH1, CH2, LINE, EXT e Trigger Coupling: AC, DC, HF Rej, TV-H (Line), TV-V (Frame) Triggering Sensitivity: !NT. DC 20MHz 1.0 Div, 20MHz - 40MHz 2.0 Div, EXT. DC - 20MHz 150mVp-p, 20MHz - 40MHz 300mVp-p • Vertical Amplifier Signal Output: 50 mV/Div. - 50 Ohm • Intensity Modulation Z Axis Bandwidth: DC - 1MHz, Sens1t1v1ty:3Vp-p • Probe Cal ibrator Output : 1 kHz square wave 1V II a 0160 $1495 .00 Price includes TWO X1/X10 Probes worth $100.00! ''l DUAL TRACKING POWER SUPPLY +/- SOV DC AT 1.0AMP SILICON CHIP APRIL '90 17 Range Digital Multimeter Voltage output: 0 to +/-50V or Oto lOOY Current output: 1.7 A from Oto ~V (+/-43.SY) !A from Oto !OOY (+/-SOY) Load regulation, better than 500mV at +/-SOY, IA Drop out indicator (5mV of ripple) Short circuit protection II Load switch - no need to switch off when switching load. K3380 with Overload Protection $229.00 Australia's best value, less than $50 Speclflcatlon: DC Voltage Range: 2V, 20V, 200V, 2000Y AC Voltage Range: 200Y, SOOY 1 1. Laboratory Series Aud io Oscillator DC Current Range: 200mA, 20 mA, 2mA, IOA ReslstanceRange: 200Ohm. 2k0hm, 20k0hm, 200k0hm, 2M0hm Diode Test Test Current: 1.0 +/6mA Q1547 $480 • Frequency Range: 20Hz to 200kHz in 4 ranges • Sine Wave Characteristics: Output voltage: 5V RMS or more at no load Distortion factor (at max output) 0.5% or less Output impedance: 600 Ohms +/-10% Output attenuator: 0 to greater than 50d8 continuously variable, • External Synchronisation Characteristics Input impedance: approx. 10kOhms Max. allowable input voltage: 10V RMS • Reading Accuracy 0.01%, +/-1 count • Frequency Counter Characteristics Display: 4 digits, 7mm red LED display Frequency range: 10Hz- 1Mhz (square wave) Sensitivity: 25mV RMS Max. input: 150V pp Input impedance: 1MOhm Square Wave Characteristics (TTL Out) Overshoot: 2% or less (at 1kHz) Rise/fall time: 200n sec or less • Power requirements: 100/120/220V +/-10% 240V +5%, -10%, 48-66Hz Another Altronics Direct Import Price Breakthrough Carry Case Q 1057 $12.50 INVERTERSINVERTERSINVERTERSINVERTERSINVERTERS POWERHOUSE 600W Get 240V AC Mains Power from your battery with these handy inverter kit sets Many combinations to choose from: INVERTER (See EA Dec'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 tools, lighting (including fluro:s) elcc motors and much more. It can be used either as a portable or a permanent fixture. • Manual or Auto Start facilities• Low battery Kit version K 6770 $425.00 Fully built and tested 12V Input K 6774 $525.00 24V Input K 6775 $525.00 ' THOME 300 WATT INVERTER WITH AUTO START Operates from 12Y Car Battery l Auto Start draws power from your battery only when appliance is plugged in and ~turned on" ie , battery can be left permanently comected if required.• Voltage Regulated • Current Regulated• Current Overload unit self limits Complete Kit K 6750 $279.00 Fully built and tested K 6755 $379.00 Two Brilliant New Multitesters From Altronics at Low Direct Import Prices a o ang1ng ultimeter a Specifications For 1 066 / 1 070 Engineering Multimeter Testers Why pay double the price for Fluke? DC Voltage Range: 200mV, 2V, 20V, 200V, 1000V • Acc uracy: All ranges+/- 0.5% rdg + ldgt Input Impeda nce: 10Mn AC Voltage Ra nge: 200mV, 2V, 20V, 200V, 750V Input Impeda nce: l0Mn , DC Cunent Ra nge: 200uA, 2mA, 20mA, 200mA, 10A Z AC Cunent Ra nge: 200uA, 2mA, 200mA, 10A Resistance Range: 200n, 2kn, 20\ill, 200\ill, 2Mn, 20Mn, 2000Mn Capacitance Range: 2000pF, 20nF, 200nF, 2uF, 20uF Transistor hFE Base DC Current : l0uA, VCE: 2.8 +/- 0.4V Gooeral: Display: 3 1/2 dign liquid crystal wnh maximum reading of 1999 Overra nge Indication: Highest digit of (1) or (-1) is displayed See our catalogue for full features and quality of this excellent Labtech Auto Ranging Digital Multimeter a 1075 Normally $99.50 This month only $89.50 Logic Tester, Frequency Counter, Capacitance and Transistor Tester Q 1070 Multimeter with Temperatu_ re Meter, Capacitance, Diode and Transistor Tester Temperature Ran ge: -2o·c lo 750' C 0' F to 1400' F Acc uracy:+/- (3 ' + 1 dgt) up to 150'C +/- 3% rdg over 150-C +/- (15' + 2 dgts) up to 225' F a 1066 $149.00 a 1067 Temp. Probe for a 1066 $29.95 Including FREE carrying case a 1076 or Holster a 1077, $12.50 value, makes a total saving of $189.00 $22.50 SAVE! SAVE! Logic Test (01070 only) Log ic 1: 2.4V +/0.2V, logic 0:07V +/- 0.2V FrequencyRange: 2kHz , 20kHz, 200kHz, 2MHz, 20MHz Input Sensitivity : 20MHz range 1V rms. Other ranges 35mV rms. a 1068 Carry Case $12.50 (suit a 1066 & a 1010) Fluke is the registered name of Fluke Instruments USA. AVIATION HEADPHONES 1 FREE with ea.eh multimeter ordered this month Why pay $400 or more for a David Clark set? BENCH AMP SIGNAL TRACER Another Altronics Kit Special! AVIATORS HEADSET WITH OIL FILLED EAR CUSHIONS see EA Apri l '88 • High performance, noise attenuating earphones. • Noise cancelling microphone • Cushioned head pad • Super sturdy • Great perfonnance • Superb, professional pilot's headset will last a lifetime with reasonable treatment. • Includes standard aircraft jacks. Here is a simple but effective audio bench amplifier. Ideal for fault find ing and experimenting and sooo inexpensive. ONLY $189.00 - - - C9070 ~..__........_, Features : • Input range 10mV to lOV in 4 ranges• Inbuilt speaker and external speaker socket • Overload indicator• Requires external 9-15V AC supply K 2100 Normally $65.00 FREE this month w ith e ach kit, K 2565 RF Probe kit worth $12.00 Now available from Altronics Dealers Polypropylene Bass Drivers Ultra High Power Capacity Our ALL NEW "Black" polyp rop cone Bass Drivers exhibit quite astonishing low reg ister reprod uct ion. Power ratings quoted are conservative. Not the cheapest but definite ly the BEST VALUE we know ol - ANYWHER E. 12" (300mm) WOOFER 100watt RMS 150W Max. C 3070 Massive 200 W Max. C 3075 60Watt RMS 100W Max. C 3065 Normally $99 Normally $129 NOW NOW ONLY $99 YOU SAVE $30 Was$69.00 NOW ONLY ONLY $49.00 $89 8" WOOFER 60Watt RMS 1OOW 61 /2" WOOFER/ Was $49.95 Midrange 30Watt RMS SOW Max. C 3055 WAS $29.95 Now$39.95 SAVE $10.00 NOW ONLY $24.00 Max. C 3060 with sealed frame 3045 Was $27 .50 c NOWYOU SAVE AT$22.00 Harris Four Channel Digital Recorder/Announcer • The Harris A2100 provides 4 channels of natural speech recording and play-back. • Record time for each channel Is Internally selectable to 10, 15, 20 or 30 seconds. • Channels can be used separately or linked to provide one long recording/announcement . Facilities/Features • Microphone Input - balanced line, low Z, • Au xilhary Input · 100KOhm 0.2V sensitivity, e.g. for CD, tape deck , Tuner, BGM line. Channel Select Pushbuttons - A, B, C, D or A+B+C+D. i.e. when activated will playback wh ichever is selected. • Sequential Pushbutton - enables playback of each channel in sequence via the Timer Switch. Timer Switch - automatically initiates the play back of the selected channel. Intervals are 10, 20, 30 seconds, 3, 6, 12 and 30 minutes and off . Re mote microphone operati on and PTT. Remote switch message actu ati on input. Line In/Line Out - zero gain circu it : ~~ :! ~GuJ oftt~~~ ~~~~tf:d~cc k etc 1 8 0 • interrupt with the recorded announcements as desired. Nicad battery backup fitted fo r memory retention. Literally dozens of applications • Mus ic on Hold Adviser - Over 50% of phone calls are placed on hold - use th is ti me to pro mote your business or prod ucts . • Information G uide - Great for displays, trade shows, self guided tours and even art galleries. • A Security Guard - Good weather or bad, holidays and weekends, it stays on duty 24 hours a day to query and direct all personnel at stores, wharehouse, plants, off ices, hosp itals and parking faciliti es. And for apartments, hotels, estates an d more • whenever you wi sh to screen traffic. • Emergency Sig nals - and/or secur~y warn ings can be generated automatically or at th e push of a button. Advertisement Announcer for Retail Stores • Either record you own ads or have them commercially produced play through your PA/BGM system as often as desired w ith th e interval ti me. • through the recorder. This line will The Protector Car Alarm Kit "The crime rate and home burglaries are increasing, so help protect your valuables by installing your own alarm system. It's so inexpensive!" Silicon Chip Feb '88 This refined car burglar alarm has about every feature you could possibly want to keep would-be thieves away. House Guard Alarm System Features:• Internal and external sire ns • Dual lamp flasher • Battery back-u p • Delayed and non-delayed inputs • rcas y to build and install. • Easy to build • One PCB • Kit includes 1.2AH back-up battery • Entry, exit delay • Panic alarm input • Lamp te lltale outputs • Auxiliary relay for exte rnal siren etc • Key switch operation • Uses most types of sensors. K 4370 EA March/April '89 NOW ONLY $119.00 BONUS OFFERII With each car alarm kit purchased this mooth we wUliocl"de fooc (4) S 5400 car alarm warning stickers, ~ BANKCARD e .. WARNING VALUED AT $12.00, ABSOLUTELY FREE! e $ 89 00 K 1910 Kit less siren • S -5170 Screecher Siren 110db $24.95 WAS $129.00 ~ FREE with each kit this month! Two (2) sets of house alarm _ stickers worth $12.00 VISA e MASTERCARD e PHONE TOLL FREE 008 999 007 e NEXT DAY JETSERVICE DELIVERY Country clients please allow an additional 48-72 hours AtTROnlC.) 17 4 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 ALTRONICS RESELLERS Chances are there is an Altron ics Reseller right near you - check this list or phone us for details of the nearest dealer. Pleue Note: Resellers have to pay the cost of freight and insuranc_ e and therefor~ the prices charged by individual (?ealer~ m~y vary slightly from this Catalogue - in many cases, however, Dealer prices will sti ll represent a significant cost saving from prices charged by Altronics Competitors. Don't forget our ExpreH Mall and Phone Order Service- for the coat of a local call, Bankcard, Vlaa or Matercard holdera can phone order for 1ame day deapatch. Blue Ribbon Dealera are highlighted with a ■. These Dealers generally carry a comprehensive range of Altronic products and kits or will order any required MORE AL TRONICS DEALERS WANTED If you have a Retail Shop, you could 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 Upto3 Kg is $8.00- 3Kg to5Kg is$20.00-Weprocess yo ur order the day received and despatch via. Overnight Jellervfce Courier for del ivery next day Country areas please allow additional 24-48 hours. HEAVY HEAVY SERVICE -All orders of 10Kgsor 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 Aus1ral ian supplier, we send goods at consignees ris k. Should you require comprehensive insurance cover against loss or damage please add 1% to order value (minimum charge $1) . When phone orderinQ 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. item for you. WA COUNTRY ALBANY BP Electronics ■ 412681 ESPERANCE Esperance Communications 713344 GERALDTON Bird Electronics 641631 KALGOORLIE -Todays Electronics ■ 212777 KARRATHA Daves Osc it ronic 854836 PORT HEADLAND Ivan Tomek Electronics 732531 WYALKATCHEM D & J P·ease 811132 NT ALICE SPRINGS Ascom Electronics 521500 Farmer Electronics 522388 DARWIN Ventronics 480030 ACT CANBERRA Bennett Commercial Electron ics 805359 VICTORIA CITY All Electronic Components 6623506 SUBURBAN CHELTENHAM Talking Electronics 5842386 CROYDEN Truscott Elect ronics ■ 7233860 PRESTON Preston Electronics 484019 1 COUNTRY BENDIGO KC Johnson ■ 411411 MORWELL Morwell Electronics 346133 QUEENSLAND CITY Delsound P/ L 8396155 SUBURBAN CAPALABAKingsway Electronics 3902399 WOODRIDGE David Hall Electron ics 8082777 COUNTRY BUNDABERG Bob Elkins Electronics 721785 GLADSTONE Supertronics 724459 MACKAY Philtronics ■ 578855 ROCKHAMPTONAccess Ele c tronics ( Eas1 S1. ) 221058 TOOWOOMBA Hunts Electronics ■ 329677 TOWNSVILLE Solex ■ 7724466 MAROOCHYDOREMals Electron i cs 436119 SA CITY Force Electron i c ■ 2125505 SUBURBAN BRIGHTON Force Electronics ■ 3770512 CHRISTIES BEACH Force Electronics ■ 3823366 ENFIELD Force Electronics ■ 3496340 FINDON Force Elec1ronics ■ 3471188 LONSDALE Force Electronics ■ 3z°60901 COUNTRY MT.GAMBIER South East Elec t ronics 250034 WHYALLA Eyre Electronics ■ 454764 TASMANIA HOBART George Harvey ■ 342233 LAUNCESTON George Harvey ■ 316533 NSW CITY David Reid Electronics ■ 2671385 CARINGHAH Hicom Unitronics 5247878 COUNTRY COFFS HARBOUR Coifs Habour Electronics 525684GOSFORD Tomorrows Electronics 247246 GRAFTON East Coast Electronic 4 3 1250 NEWCASTLE Novocastrian Elect.Supplies 621358 RAYMOND TE!IRACE Alback Electronics 873419 WINDSOR M & E Electronics 775935 WOLLONGONG Newtek Electronics ■ 271620 Vimcom Electronics 284400 WAGGAWAGGA Phillips APESKY INSECT TO ANNOY YOUR FRIENDS Horace the cricket always chirps back whenever he hears a noise. If you keep quiet, so does Horace. Make a noise and he joins in and flashes his LED eyes at the same time. He can also be concealed to play his favourite game of hide and seek. By JOHN CLARKE PARTS LIST You know how crickets can be quite annoying at night. You can hear the little beggars chirping away somewhere under the lawn but when you go creeping out to find them, they shut up until you go away. And so you should, you intolerant humanoid! But why should crickets be confined to the great outdoors? Why not have your own pet cricket who can pester people when you want him to? So here's Horace, the electronic cricket. He's a 6-legged beastie, fully house-trained and under your command. Horace incessantly chirps away while there is any noise or talking going on and he only stops when the noise ceases. We are sure that our readers will be very resourceful in finding uses for Horace. And Horace is inexpensive. He only uses a single cheep (sorry cheap) IC and a few other bits and pieces all built onto a PC board. The board itself becomes Horace's body and the battery his belly. He also has a couple of LEDs for eyes, a miniature microphone mouth, a slider switch tail and six resistors for legs. He has a certain jaunty style, aided by the springyness of his resistor legs. 66 SILICON CHIP Best of all, Horace is easy to build. So let's see how he works. Circuitry The circuit for Horace uses just one low power quad op amp IC, an LM324. It is ideal for this task since it will operate happily from a single low voltage supply and has a low current drain of 3 milliamps or less. Horace has two modes of operation. The first is the "listen" mode, whereby Horace listens with its electret microphone for any noises. Having detected a noise above the threshold level, the circuit switches into its "chirping" mode. Only one mode is possible at any one time, so that the circuit can only listen or chirp - it can't do both at the same time. In the listen mode, IClc functions as a non-inverting amplifier with a gain of 455, as set by the lMQ and 2.ZkQ resistors connected to pin 9. The non-inverting (+)input of IClc, pin 10, is biased to about + 4.5V by the lO0kQ resistor connected to pin 13 of ICld. During listen mode, the pin 14 output of ICld normally sits high (ie, + 9V). This is because of the way in which the inputs of ICld are biased. The lMQ pullup resistor at pin 12 1 PC board, code SC08106901, 91 x 61 mm 1 electret microphone insert 1 piezo transducer 1 9V battery holder (DSE Cat. S-61 50 or equivalent) 1 9V 216 battery 1 subminiature DPDT slider switch 2 PC stakes Semiconductors 1 LM324 quad op amp (IC1) 1 1 N4148 diode (D1) 2 red LEDs (LED 1, LED 2) Capacitors 1 1 0µF 16VW PC electrolytic 2 0.22µF RBLL or tantalum electrolytics (or monolithics) 2 .039µF metallised polyester Resistors (0.25W, 5%) 3 1MQ 1 4.7kQ 9 1 00kQ 1 2 .2kQ 1 22kQ 1 1 kQ 6 1 0MQ 1W (for legs) Miscellaneous Solder, tinned copper wire , 5 screws and nuts for battery holder and piezo transducer. and diode Dl holds this input at one diode voltage drop above the output voltage of IClc. And the pin 13 inverting input is effectively at the +9V 10 100k ~, + 16VW.,._ 100 k s+11, J + J 100k .039 T 9V : ...I... ELECTRET MICROPHONE l 100k PIEZO TRANSOUCER 100k 2.2k 22k .I,;" C3 ... 0.22I 100 k RBLL - .,. . 0391 1M 10Mi 1W LEG1 10Mf 1W LEG 2 10Mf 1W LEG3 I I 10M 1Wf LEG4 10Mf 1W LEGS 10M' 1W LEG6 ""'~ 100k .,. LE02 ~ i HORACE same voltage as the output of IClc since IClc itself is biased from pin 13. This incestuous arrangement means that pin 12 of ICld is normally above pin 13 and therefore pin 14 is high. Chirper and LED driver IClb provides the chirp part of the circuit. It is an oscillator which drives the piezo transducer but while ever pin 14 of ICld is high, !Cl b can't function; similarly with ICla, which is the LED driver for Horace's eyes. We'll come back to these two op amps later. Now let's go back to the front of the circuit to the electret microphone. This is biased from the 9V supply via a 4. 7kQ resistor while the input signal is fed to pin 10 of IClc via Cl, a .039µF capacitor. With the circuit in the listen mode, the electret generates a signal voltage which is amplified by IClc. For louder sounds, the output of IClc swings strongly up to the positive rail and down to the 0V rail. The negative swings of the signal pull pin 12 of ICld low and so pin 14 flicks low too. Once that happens, the whole circuit is in the chirp mode. With pin 14 of ICld low, pin 12 is pulled down low too, via the associated lO0kQ resistor and this means that ICld is " latched". It will stay that way until the capacitor at pin 13 can discharge sufficiently for pin 13 to get below pin 12 (which is at about + 0.BV). Until that happens, ICl b is "enabled" as a Schmitt trigger oscillator with its frequency set by the 22kQ . resistor and .039µF capacitor connected to pin 6. It functions as follows: initially, pin 6 is high and the output at pin 7 is low. The .039µF capacitor begins to discharge via the 22kQ resistor until it reaches the lower threshold of 3V (set by the lO0kQ resistors connected to pin 5). Then the output of IClb [pin 7) goes high and begins to charge the .039µF capacitor via the 22kn resistor. This continues until the upper threshold of 6V is reached when the output of ICl b again goes low. This cycle repeats itself and so ICl b oscillates at around 1700Hz to drive the piezo transducer. While IClb is oscillating, ICla turns on the two LEDs at its output. This is because ICla is connected as an Schmitt inverter. When its pin 2 input is low, its output at pin 1 Fig.I: the circuit is based on a single quad op amp IC. IClc is the microphone amplifier and this controls Schmitt trigger oscillator ICld. ICld in turn controls chirp oscillator IClb, while ICla drives the LEDs. is high and this drives the LEDs via a lkQ resistor. So while ever ICld's output at pin 14 is low, the LEDs are alight and the piezo transducer is sounding. None of this sound and light la sts for long though, since the circuit conditions around IClc and ICld don't stay constant. Tone modulation Recall now that pin 10 of IClc, the audio amplifier stage, is normally biased to about + 4.5V via the lO0kn resistor from pin 13 of ICld. When ICld's output flicks low, this bias voltage is removed and so IClc can't function as an audio stage. Instead, the 0.22µF capacitor (C2) on pin 9 begins to discharge from 4.5V via the 2.2kQ resistor and the lMQ resistor to the output of IClc. Some discharge current also flows via the pin 9 inverting input but this is small enough to ignore. The discharge time for CZ is about 200 milliseconds and during this time, the 0.22µF capacitor (C3) AUGUST 1990 67 9V 4.5V "\ IC1c, PIN B Fig.2: this diagram shows the waveforms at various points on the circuit. Notice how the output of IC1d switches high & low to modulate the output of IC1b. at pin 13 is being rapidly charged and discharged. C3 charges and discharges because ICld is now operating as an oscillator by virtue of the lOOkO resistor connected between pin 13 and pin 14. So ICld's output doesn't stay low as we implied. OK, so we led you astray but you'll get the whole picture bye and bye. Thus, ICld's output actually flicks low and high at about 70 times a second (70Hz) and this frequency switches on and off (modulates) the tone produced by ICl b and thus makes it sound richer. The voltage at pin 10 of IClc is essentially the same as that across C3 except that it is filtered by the associated lOOkO bias resistor and Cl. When the voltage at C2 finally discharges below that at pin 10, IClc's output goes briefly high which allows ICld to revert high again too. This puts the circuit back into listen mode and the output of IClc settles back to around + 4.5V. The waveforms of Fig.2 show the circuit functions graphically. The first waveform shows pin 8 of IClc. It starts off sitting at about + 4.5V but with noise superimposed. Then it flicks negative as a strong noise signal is picked up. This causes Cl, C2 & C3 to discharge at different rates, as shown in the second waveform. The third waveform shows the output state of ICld which may be thought of as controlling the whole circuit. Finally, the 4th diagram shows the high frequency waveform which drives the piezo transducer. Construction As noted above, Horace is basically a PC board with a 9V battery slung underneath and the whole lot suspended on six resistor legs. The PCB is coded SC 08106901 and measures 91 x 61mm. Check the board carefully for un- This view shows how the battery holder is mounted. You will have to bend the two leads so that they go through the holes in the board. drilled holes or shorted or open circuit tracks. Fix these first before going further. Assembly can begin by inserting the two PC stakes used for terminating the piezo transducer. Now insert the low profile components such as the links, resistors, diode and IC. Be careful with the orientation of the diode and IC. The piezo transducer is mounted using two small screws and nuts directly onto the PCB. If these have not been supplied you could use a Fig.3: this is the full-size PC pattern for Horace. RESISTORS D D D D D D D 68 No 3 9 1 1 1 SILICON CHIP Value 1MO 100k0 22k0 4.7k0 2.2k0 1k0 4-Band Code (5%) brown black green gold brown black yellow gold red red orange gold yellow violet red gold red red red gold brown black red gold 5-Band Code (1%) brown black black yellow brown brown black black orange brown red red black red brown yellow violet black brown brown red red black brown brown brown black black brown brown ELECTRET MICROPHONE Fig.4: here's how to install the parts on the PC board. Take care with component orientation and note that the battery holder (shown dotted) mounts on the copper side of the board. You can use any value 1W resistors down to 10k0 for the legs. piece of double-sided tape or a spot of Superglue. The wires from the transducer are cut short to terminate to the PC stakes. Note that although the + sign is shown on this transducer, the polarity is unimportant. Next, the capacitors can be installed. Make sure that the electrolytics are oriented correctly. Cl & C2 must be low leakage aluminium or tantalum electrolytics or monolithics. If you use monolithics, you don't have to worry about the polarity. The two LEDs are mounted with long legs which are then bent over, as shown in the photos. The longer lead of each LED is the anode. The miniature slide switch is mounted directly on the PCB. The electret microphone is mounted on Don't stomp on poor Horace if he fails to work first time. Instead, check your work carefully against the wiring diagram (Fig.4). In particular, check the polarity of the IC, LEDs and microphone. two short lengths of 1mm tinned copper wire so that it stands about 10mm above the PCB. Note that the electret is polarised and the negative terminal is the one which is connected to the microphone body. The legs are simply lOMO lW resistors which are mounted at one end of their leads. The free end is folded over for a rounded foot. Actually, you can use resistor values down to about 10k0 for the legs but don't go below this.figure otherwise you risk excessive supply loading if the unit is placed on a metal surface. Before installing the battery holder, it is best to try out the circuit first since the holder obscures many of the tracks underneath the PCB. Use some short leads to temporarily connect power to the circuit. It should operate when switched on - by chirping and switching on the LEDs whenever you make a sound. Troubleshooting If Horace does not work, don't fling him across the room. Check your work very carefully against the wiring diagram. Are all the component values correct? Is there any sign of shorts because of solder splashes underneath the board. Still no sign of life? Use your multimeter, switched to a DC volts range, to check for + 9V betwe.e n pins 4 & 11 of the IC. If that checks out, briefly short pin 14 to pin 11. This should cause the piezo transducer to sound and the LEDs to light. If so, the fault lies in the circuit associated with IClc & ICld. Check the circuit very carefully for wrong components or components installed the wrong way around. Briefly shorting pin 8 to pin 11 should also cause the LEDs to light and the piezo transducer to sound. Any deliberate short circuits applied in this way should only be of brief duration though, otherwise you run the risk of blowing the IC. Finally, the battery holder can be installed. The two leads from it require bending so that they will fit into the PCB holes. This is done so that the leads can be soldered easily on the underside of the PCB. The battery holder is secured to the PCB using screws and nuts. A UGU ST 1990 69 COMPUTER BITS By JENNIFER BONNITCHA What to do when your computer goes bung; Pt.4 Many computer problems can be quickly diagnosed using the CHKDSK command. This month, we take a look at CHKDSK error messages and also cover power supply & keyboard problems. The DOS program CHKDSK is one way to analyse the directory and file allocation table on a hard or floppy disc. The end result is a table showing the number of files currently stored on the disc, together with an availability report of disc space and memory. It looks like this: xxxxxxxx bytes total disk space xxxxxx bytes in x hidden files xxxxxx bytes in x directories xxxxxxxx bytes in x user files xxxxx bytes in bad sectors xxxxxxxx bytes available on disk xxxxxx bytes total memory xxxxxx bytes ·free Problems with a faulty File Allocation Table (FAT) can often be detected through CHKDSK. The FAT records the position of each file on a disc and the location of each piece of information the file contains, and allocates free space so you can create new files. Rather than actually recording the contents of each sector, the FAT actually records information in groups of sectors called clusters. CHKDSK error When CHKDSK detects an error, you will often see messages like: xx lost Clusters found in xx Chains or File x Cross-Linked on Cluster x 70 SILICON CHIP If you specify the IF (Fix) switch with CHKDSK, you will be asked to convert lost chains to files. If you answer Yes, then CHKDSK gives each fragment a name, starting with FILE0000.CHK then FILE000l.CHK and so on. You can then examine the contents of the files using, for example, the TYPE co~mand. If you answer No, the lost cluster pointers are erased. Somehow the DOS file structure of the disc has been damaged. This typically occurs when a program manipulates the FAT or directories. Sometimes a normally well-behaved program can go berserk. Sometimes a program terminates before any open files are closed. A lost cluster is a unit of storage with a pointer saying the cluster is in use by a file but no directory entry knows anything about that cluster. Since files may be fragmented on a disc, DOS is reporting a discrepancy in the FAT - the link to another part of the file has been lost. File allocation table When a disc is formatted, the FORMAT command creates an empty Root directory to hold the FAT. Every disc in fact has two FATs, so DOS can compare the contents of each. If one copy is damaged, DOS will use the other. However DOS can't decide which of the FATS is more correct than the other. If a discrepancy is detected, DOS tells you: File Allocation Table bad for drive X This means the copy in memory of one of the allocation tables points to nonexistent blocks. Possibly the disc has been incorrectly formatted. However, if the problem occurs on a disc you have been using for some time, reach for your backup discs. Programs like Norton Utilities, PC Tools and Mace Utilities can help rejoin the files created by CHKDSK. CHKDSK is OK as a quick way to sort out simple problems. Software programs like Norton Utilities and Mace Utilities enable you to make a duplicate of the FAT on an unused area of the disc where it can be read if the original or backup FAT is damaged. Another method of checking for problems is to use a disc optimisation program. These programs move all data firstly to the centre of the disc then progressively back to the outer edges. The advantages are two-fold. First, the files are positioned at the outer edge of the disc so the read/write heads don't have to travel so far to locate the data and second, the files are no longer fragmented, thus reducing the possibility of lost chains. Certainly operating systems have become smarter when it comes to allocating disc space, but large files and discs nearing full capacity still require allocation, dependent on Magic Box Shares One PC Between Two Terminals Does your computer sit idle on your desk for most of the day? Why not let someone else use it while you are doing other things? By using this device, it is possible to let someone else share your machine while you stay at your desk. Called the "PC-Share Magic Box", it enables two video monitors and two keyboards to be connected to any PC XT, AT, PS/2/25 or 30, or PCAT-386. the available space. It's a good idea to run disc optimiser programs at regular intervals to really springclean your disc. Other FAT errors include the message: Probable Non-DOS Disk This often occurs on a hard disc when the FAT has been altered. The implication is that somehow the FAT has changed and should be given priority attention. Of concern is the fact that something (or someone) has overwritten a part of the disc normally out of reach. FORMAT and FDISK traditionally twiddle with this area of the disc, however you could have conflict with device drivers or memory resident software. The obvious treatment is to reformat the disc. Once again Norton Utilities, Mace and PC Tools etc can help you, which is great if you don't really have lots of time to spare. You do, however, need to have a working DOS disc available to boot In normal use, one user can watch the other's work as it is produced but if you are sharing an AT-286 or AT-386, it is possible to blank the unused station 's monitor by pressing the NUM LOCK key several times. Not a bad idea, eh? PC-Share is available from Rod Irving Electronics (7 4 Parramatta Road, Stanmore) for $299 plus the cables . the computer initially. The problem is with the first value of the FAT, the Media Descriptor Byte. It is normally defined as F8 for the hard disc and if CHKDSK detects anything else, the Non-DOS message eventuates. Refer to your favourite utility program for instructions on setting the descriptor right. FE 160K single sided disc FC 180K single sided disc FF 320K double sided disc FD 360K double sided disc F8 hard disc F9 720K, 1.2M or 1.44M disc F0 other The power supply Heading the list of likely computer troublemakers is the power supply. It uses a switching regulator to convert the mains voltage into something the computer can use, usually 5V and 12V DC rails. The electronic components and circuits of the motherboard, adapter cards and disc drive logic boards use the 5V power, while the disc drive motors and fans use the 12V power. Naturally, the system needs a steady supply of both to function effectively. At system startup time, the power supply completes a series of internal checks to ensure that adequate power levels are achieved prior to allowing the PC to continue. When it is satisfied that all is well, a signal is sent to the motherboard. If the signal is not sent, the computer will go no further. Common symptoms of a faulty power supply are: (1) power switch on; (2) fans running; (3) hard disc running; (4) not much else happening. Failure can occur due to overloading, power surges and normal AUGUST 1990 71 defects brought about by conditions such as thermal expansion or contraction (read overheating, etc). The fan in a power supply can also fail. This problem is quite easy to recognise - prior to failure, the fan runs at an increasingly slow rate and in its death throes, tends to make strange noises. Power supply problems can occur when you purchase additional/more powerful disc drives, 8087 chips, hard discs and memory devices. Remember that power is needed to run all these devices and the more devices you add, the more you overtax a possibly inadequate power supply. Poorly engineered power supplies can also run hot, causing the system to do likewise. Repeated heating and cooling of electronic components can lead to system failure since the hotter the component becomes, the shorter its life expectancy. Repeated heating and cooling causes metal to harden and become brittle. Since many components are soldered, the same principle applies. Devices connected via sockets can also work loose, thus causing possible corrosion of the sockets and connector joints. When a power supply "blows", it is frequently the result of cracked or broken solder joints. Keeping the unit at a constant temperature will certainly prolong the life of your system and this is one reason why you will hear some people say they leave their computer running constantly. Only you can judge. When replacing a power supply, make sure you specify the kind of PC you are using, as well as the desired wattage. The shape of the power supply varies from model to model (ie PC/XT to AT etc ), together with the size, screw hole positions, number and type of connectors and switch position. Keep on keying The keyboard is the most frequently used and most obvious method of communicating with your PC and so it is in your best interests to treat it gently. It is really an intelligent device - in fact, it is a computer in its own right. Keyboards also contain built-in memory to enable them to perform their own self-test when powered on. There are now three main types of keyboards in the compatible world: (1) the 83-key PC & XT keyboard; (2) the 84-key AT keyboard; and (3) the 101-key enhanced keyboard (with and without LED panel indicators for CAPS, SCROLL & NUM LOCK). Any of the PC or XT type systems cannot operate the lights because they do not have the necessary interface for light operation. Thus you need different keyboards depending on your computer; the PC/XT keyboard is the same, Keep liquids and dust away from keyboards and give the keyboard a vacuum or brush down at regular intervals. It's also a good idea to use a dustcover to protect the keyboard when it is not in use. 72 SILICON CHIP although usually switchable as appropriate, while the AT uses the enhanced keyboard. Often the ROM BIOS of the PC/XT may not be able to operate the enhanced keyboard correctly. This is typical when the NUM LOCK light does not come on automatically when the system unit is turned on. Problems with the keyboard can also arise if it is not securely attached to the system unit or if it is removed while the computer is switched on. Most computers cope very well with this but some will lock out the newly plugged in keyboard. Make sure you save any work on the screen if you need to change the keyboard for any reason, just in case you have to reboot. As with discs, liquids can mean death for a keyboard. Spilled drinks running between the keys can dramatically increase the risk of short circuiting since water is a conductor of electricity and you may need to replace the keyboard. Turn off the computer ASAP. However all may not be lost disassemble the keyboard and use distilled water to wash, yes wash, the keyboard. All circuit boards are washed during the manufacturing process. You need to make sure the keyboard is perfectly dry before you attempt to use it again. Keyboards also suffer from the mere fact of constant use. Under seige from a heavy-handed, greasyfingered operator, it is little wonder that the keys eventually give up the ghost and start sticking. Also, as dirt and dust settles between the keys, they will require greater pressure from the pinkies to type the correct letters. To prevent this problem, vacuum the keyboard regularly and keep it covered, particularly if you work in a dusty environment. Turn the keyboard upside down and give it a good shake, especially if there are foreign objects like pins and paper clips trapped inside. If you are feeling adventurous, carefully remove the keytops and gently spray with compressed air or brush around the key connectors. Take care not to remove too many keytops at once unless you are completely familiar with the keyboard layout. ~ f/-ette#Uf SHdd 4- Our prices are like the business . .. I BOARD SOLUTIONS Pty Ltd I MOTHERBOARDS ***NEW!!! BUILT-UP SYSTEMS*** 10MHz XT, (640K) OK RAM M1010 115.00 10MHz XT, (1 MB) OK RAM M1000 149.00 31MHzXT2860KRAM M1020 225.00 Baby 286 12MHz OK RAM M2015 399.00 Baby 286 12MHz OK RAM VLSI M2030 449.00 Baby 286, 12MHz VLSI OK Neat M2020 499.00 286, all-in-one, OK RAM M2010 545.00 16MHz NEAT 286 OK RAM M2040 599.00 20MHz 286 OK RAM M2045 845.00 16MHz 386SX, OK RAM M3000 895.00 25MHz 386, 32K Cache, OK Neat M3010 1995.00 33MHz 386, 32K Cache, OK M3o2o 2795 _00 . . - - - - - - - -- - - - - -- - , XT (8088) 10MHz System X1010 XT (8088) 31 MHz System X1030 286-12 (80286) System X2859 286-12 (80286) VLSI System X2861 286-12 (80286) NEAT System X2860 286-20 (80286) 20MHz System X2862 386SX (80386SX)16MHz System X3861 386-33 (80386) 33MHz System . X3863 C I_ P S........, ! I....._ _ _ _ _ _ _H __ __ . I 1M RAM Chip- 100nS 1M RAM Chip - 80nS 256K RAM Chip - 1OOnS 256K RAM Chip - 80nS 8087-2, 8MHz Co-Processor 29300 29380 29400 29480 29500 29 .95 32.95 7 .95 8.95 275.00 4 X 256K RAM Chip, 1OOnS 4 X 64K RAM Chip, 120nS For VGA card 64K RAM Chip - 120nS NEC V20 Chip NEC V20 Chip, 10MHz NEC V30 Chip, 10MHz 64K RAM Chip - 1OOnS 80387SX 16MHz Co-Processor 64K 100ns RAM Chip 2C87-8MHz (equiv 80287/8) 2C87-10MHz (equiv 80287/ 10) 2C87 ~ 12MHz (equiv 80287/12) 2C87-20MHz 3C87-16MHz (equiv 80387/16) 3C87-20MHz (equiv 80387/20) 3C87-25MHz (equiv 80387/25) 3C87-33MHz (equiv 80387/33) SIMM Module, 1MB 80ns SIPP Module, 1MB 80ns 29200 32.95 29212 29112 29000 29010 29020 29210 29540 29210 29550 29555 29560 29565 29570 29575 29580 29585 29680 29690 12.00 4.95 24.95 39.95 49.95 5.45 795.00 5.45 449.00 495.00 549.00 649.00 649.00 749.00 949.00 1099.00 295.00 295.00 I 895.00 1095.00 1225.00 1595.00 1695.00 2050.00 1995.00 4795.00 All systems are fully built and tested, with RAM fitted . Simply add the video card and monitor of your choice. 12 months warranty applies to all Board Solutions Systems. INTERNAL FLOPPY DISK DRIVES YE-Data 360K YE-Data, 720K/1.44M D3000 drive Plus Frame YE-Data, 1.2MB D5500 D3000 D3010 D5510 I 149.00 184.95 199.00 175.00 INTERNAL HARD DISK DRIVES . NEC 42MB, 28mS 3.5in D8000 plus Frame M'scribe 40MB AT BUS 3.5in Kalok 20MB 40mS Seagate 20MB ?Oms RLL inc XT controller. Seagate 20MB 65ms RLL inc XT controller Seagate 30MB 65ms MFM inc XT controller Seagate 40MB ?Oms MFM inc XT controller Seagate 5.25in 40MB 40ms RLL Seagate 5.25in 40MB 28ms RLL Seagate 5.25in 65MB 40ms RLL Seagate 5.25in 65MB 28ms RLL Seagate 42MB 24ms V/C EXTERNAL FLOPPY DISK DRIVES For Amiga 500, 1000, 2000, 3.5in 880K For Amiga 500, 1000, 2000, 5.25in 360/880K For Commodore PC1 , 5.25in 3601720K 40/80 track For Atari ST series, 3.5in 720K For Atari ST series, 5.25in 3601720K 40/80 track For Amstrad PC1512/1640, 3.5in 720K For IBM XT, 3.5in 720K XT For IBM AT, 3.5in 1.44MB For IBM XT, 5.25in 360K For IBM AT, 5.25in 1.2MB For TOSHIBA laptop series, 5.25in 360K For TOSHIBA laptop series, 5.25in 1.2MB D9500 249.00 D9510 299.00 D9520 D9530 299.00 299.00 D9540 299.00 D9550 D9560 D9570 D9580 D9590 269.00 299.00 329.00 299.00 329.00 D9600 349.00 D9610 399.00 I L____________ __. MICE & JOYSTICKS D8000 D8010 D8020 D8100 . 745.00 775.00 795.00 399.00 D8200 529.00 D8210 575.00 D8220 629.00 D8230 D8240 D8250 D8260 D8270 D8390 675.00 775.00 795.00 849.00 899.00 849.00 . Joystick PC/XT/AT 3 Button Serial Mouse Mouse Mat J1000 J1030 J1040 34.95 69.95 7.50 I MONITORS· Monitor, 14in TTL, Amber Monitor, 14in TTL, Green Monitor, 14in TTL, Paper White Monitor, 14in EGA Monitor, 14in VGA Monitor, 14in Multisync I M9000 M9010 M9020 M9030 M9040 M9050 249.00 249.00 249.00 599.00 749.00 899.00 MICRO CHANNEL Dual Sync Adaptor, PS/2 2MB RAM Card, PS/2 OK RAM 8MB RAM Card, PS/2 OK RAM PHONE OR FAX NOW FOR LATEST PRODUCTS. PRICES AND INFORMATION OOPS! OVERSTOCKED ALL-IN-ONE "AT" MOTHERBOARD: SLASHED BY $100 - ONLY WHILE THEY LAST! Here's a sensational bargain - if you're quick! We're dramatically overstocked on these superb '286 motherboards which include serial and parallel ports and hard/floppy controller on board. Update your old XT snail to AT performance! Normally fantastic value at $545.00; Our suppliers have really because we're overstocked we've done it this time: they didn't slashed the price - only while stocks see the decimal point and last - by a massive $100.00 I MC1000 299.00 MC1010 349.00 MC1020 599.00 WHATA BOO-BOO! sent ten times our order. Our difficulty is your opportunity: YOU REAP THE BENEFIT! HURRY! THIS MONTH ONLY OR UNTIL CURRENT STOCKS SOLD! 1/0 CARDS 2 Ser. 1 Parallel Games, Parallel & 2 x Serial Chip Set & Cable suit 11040 Multi 1/0 Card XT only Multi 1/0 Card, 2 Ports all 4 drive types supported (XT Only) Parallel Printer Card (XT/AT) Serial PortCard X 1 (XT/AT) Serial PortCard X 2 (XT/AT) 1/0 Plus Card - XT Only Serial/Parallel Card - XT/AT 2 Serial , 2 Parallel, AT Games, Par, Serial XT/AT Multi-Serial Card , 4P-AT I 74.95 99.95 29 .95 129.00 i1010 i1020 i1030 i1040 i1050 i1060 i1070 i1080 i1090 164.95 29 .95 54.95 69 .00 99 .00 64.95 84.95 89.00 245.00 I VIDEO CARDS VGA Card, 800 x 600 (256K) VGA Card, 1024 x 768 (512K) Magic Combo CGA Card EGA Card Mono Hercules Card, 16MHz operation + Parallel Port V1000 V1010 V1020 V1035 299.00 399 .00 129.00 179.00 V1040 99.00 POWER SUPPLIES 200 Watt PSU Suit Tower Case 200 Watt PSU Suit Baby T Case 150W PSU, Circuit Board 150W Switching PSU - XT 200W Switch PSU - Baby AT 200W PSU , Baby AT, L Type 220W Switching PSU -AT 200W PSU With Battery Backup 150W PSU Cap. 220nF/200V I P2020 P2030 P1500 P1510 P2000 P2010 P2200 P2040 P9000 KEYBOARDS 84 Key Keyboard XT/AT 101 Key Keyboard , XT/AT 101 Key Keyboard + TrackBall K1000 K1010 K1020 INTERFACE CARDS RAM CARDS i1080 i1110 i1041 i1000 RAM Card, OK RAM , XT only 2MB RAM Cd, OK LIM/EEMS AT 2MB RAM Cd, OK LIM/EEMS XT 6MB RAM Card, -OK RAM 4MB Fast Card Suit 20MHz +SX 32 Bit RAM Card 25 + 33MHz R1000 R1010 R1020 R1030 R1040 R1050 99.00 265.00 245.00 295.00 299.00 349.00 DISK CONTROLLER CARDS Floppy Disk Card, 4 Ports 360K Disk Cont 4 port, 2In 2Ex or 4In Floppy Disk Card All Drives ESDI Hard Disk Cont Card -AT ESDI HDD/FDD Card - AT Hard Disk Cont, 1:1 lnt. AT HDD/FDD Cont, 1:1 lnt. AT Hard Disk Cont,1 :1 lnt. RLL , AT HDD/FDD Cont, 1:1 int, RLL, AT SCSI HDD/FDD for AT Hard Disk Controller, XT Hard Disk Controller, RLL-XT I E1000 E1030 E1010 E1040 E1050 E1060 E1070 E1080 E1090 E1105 E1110 E1120 55.00 134.95 99.00 349.00 425.00 245.00 275.00 249.00 285.00 275.00 134.95 154.95 CASES Hinged, Baby AT Full Size Hinged AT Case 195.00 Hinged Baby AT w/200W PSU 149.00 Slimline 'XT' or 'AT' with PSU 85.00 3.5in Hard Disk Ext + Cable 124.00 5.25in Floppy Disk Ext. + Cable 149.00 · 5.25in Full Height Ext. + Cable 149.00 5.25in Mount for 3.5in Drive 195.00 Baby Tower Case AT 695.00 Baby Tower Case+ 200W PSU 3.95 Tower for 6 Dev . (4 front, 2 rear) Tower for 6 Dev . (4 front , 2 rear) & 200W PSU Tower for 6 Devices, (6 front) 95.00 Tower for 6 Devices, (6 front) 115.00 + 200W PSU 199.00 Case, hinged XT C1000 C1005 C1010 C1020 C1030 C1040 C1050 C1060 C1070 C1080 C1090 139.00 199.00 249.00 275.00 99.00 115.00 125.00 25.00 189.00 325.00 399.00 C1100 C1120 549.00 399.00 C1130 C1140 549.00 95.00 48 Line 1/0 Card F1130 Serial RS-422 Adaptor F1140 Industrial 1/0 Card F1150 Universal Wire-wrap Card F1030 Dual Serial RS-422 Card F1040 80286 Speed-up Card F1050 IEEE 488 Interface Card F1060 IEEE 488 Interface Card- National Compatible F1070 A-D/D-A Converter, 12 bit, 1 Ch. F1080 A-D/D-A Converter, 12 bit, 2 Ch. F1090 Clock Card - XT F1100 F1110 EPROM Writer Card Games Card- 'XT'& 'AT' F1120 110.00 135.00 445.00 125.00 195 .00 495.00 445.00 595.00 199.00 599 .00 49.95 245.00 35.00 NETWORK SK Ethernet 8 bit with T Adaptor 16K Ethernet 16 bit with 'T' Adaptor Ethernet 50 Ohm Terminator Thin Ethernet Cable , 25 feet Thin Ethernet Cable, 50 feet Thin Ethernet Cable, 75 feet Auto Boot ROM for NEE1 Workstation , 12MHz Diskless, with 1MB RAM N1000 399.00 N1010 N1020 N1030 N1040 N1050 N1060 449.00 12.75 35.00 49.00 62.00 79.95 N2000 1695.00 CABLES OH NO ! We've run out of room to show you our great range of cables, connectors and gender benders. For details of any of these products, call Board Solutions today. No obligation, of course! PHONE OR FAX NOW FOR LATEST PRODUCTS. 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PLEASE CALL ! • 14 Day money-back guarantee (except software) • At least 6 months warranty on all our products. • Mail orders are our speciality! • Road Freight on normal size items is $9.00 • Insurance $1.00 per $100 of order value • All prices INCLUDE sales tax • We accept Visa, Bankcard, Mastercard and Post Office COD • Call for latest price list • Special prices apply until August 31, 1990 or while stocks last ! • Leasing facilities available: just ask! • Government pricing available on request BOARD SOLUTIONS IS YOUR ONE-STOP PC ENHANCEMENT COMPANY ~S~:t BOARD SOLUTIONS PO BOX 1120, LANE COVE NSW 2066 TEL (02) 906 5696 FAX (02) 906 4592 Dick Smith Electronics say . .. Look to the Future Board Solutions say ... Look to the Future, to the Features AND to the Price! HERE ARE 4 BETTER REASONS WHY YOU WON'T BUY YOUR NEW 386SX COMPUTER FROM DICK SMITH ELECTRONICS: YOU'LL BUY IT FROM BOARD SOLUTIONS! 1 • • • • • • • • THE COMPUTER • Famous brand Ultima 386SX • Truly super fast 20MHz 80386SX (not the slower 16MHz version they sell) • 12120MHz speed keyboard or software switch able 1MB RAM on board, expandable to a massive 10MB (theirs expands to only 5MB) 42MB 28ms voice coil hard disk drive 1 .2MB 5-1 /4in disk drive Western Digital hard/floppy disk controller card 16Bit 256K VGA Card 2 serial, 1 parallel ports built in 14in VGA Colour Monitor (not a "monochrome VGA" ours is true VGA colour included in price!) Mini tower case with LED display 2 THE QUALITY Ultima offers outstanding reliability and cost effectiveness. Crafted using the latest surface mount technology, all systems are fully QC'd during assembly in the factory, and then undergo complete quality control again at Board Solutions before being despatched to you. All Ultima computers from Board Solutions carry a full 12 month "back to base" warranty. We're so confident we offer all purchasers our 14 day money-back satisfaction guarantee . 3 THE SUPPORT If for some reason you need to return your 20MHz 386SX Ultima Computer, we will guarantee to have it repaired and ready to despatch within 48 hours (normal turnaround is less than 24 hours). Why wait up to six weeks with some other companies? 4 THE PRICE Remember, this is a 20MHz 386SX, not 16MHz. Remember, this includes a colour VGA monitor, not a $500 "option"! OUR PRICE: Only s2995 Retail Customers Only including VGA COLOUR Monitor you don't have to add a thing! PHONE, FAX OR MAIL ENQUIRIES WELCOME f/e'Ze#Uf Smttlt :t BOARD SOLUTIONS Ply Ltd PO BOX 1120, LANE COVE NSW 2066 TEL (02) 906 5696 FAX (02) 906 4592 Advertising with high power lasers projected onto the sides of city buildings is soon to become a reality in Australia and in fact, we lead the world in the development of this technology. SILICON CHIP recently took a look at these highpowered lasers which are controlled by computer. By LEO SIMPSON Just when you thought that advertising had gone about as far as it could go, a brand new technology has popped into place to give the marketing people another way of delivering their message. Just recently, Sydney City Council has approved in principle the use of Laservision for advertising on the sides of large city buildings. And with Sydney leading the way, other Australian cities are sure to follow. Laservision is in fact the name of Laservision (Aust.) Pty Ltd. They have developed and own the technology for controlling high power lasers so thatthey can produce almost any image imaginable. The lasers they use to project images on the sides of buildings, the Sydney Opera House or at the State of Origin rugby league matches are big - 5 to 20 watts. They are also to take delivery of the world's most powerful visible laser, capable of producing 32 watts. While such a power rating may not seem big, in terms of lasers it really is big. And if you think about the really low efficiency of laser tubes, like less than .05%, then the power input to these devices is quite significant - tens of kilowatts. Mirror, mirror As you might expect, to make a high power laser write on a wall or cliff which may be a kilometre in the distance, you don't move the laser, you move the beam. It's all done with mirrors. But there's no way you can 76 SILICON CHIP accept that glib explanation and then move onto another subject. Laservision Australia has spent some 8 years developing the control technology for writing with lasers and they reckon they are still refining it. At the moment they have the only system available worldwide which can be programmed in real time to control a laser display. You can sign your signature on a digitiser panel and have it blown up to 50 metres wide by the laser - instantaneously. The result is that Laservision's system is booked for advertising and media displays all around the world. In fact, if you see an overseas sourced video news item featuring a large laser display, the chances ar.e that it is a Laservision show. Animated advertising So what are the ramifications of having permanent laser advertising on the sides of city buildings? One of the big advantages of laser vision advertising is that it does not require any large supporting structure. As long as there is a large blank wall in clear view, that is all that is needed. There is no need for a large bulky billboard structure which is costly to put up in the first place and then costly to pull down when it is no longer needed. The second big advantage comes about because of the immediate programmability of the Laservision 1 Co~™110111CA~TI((l r, Laservision displays can be projected from very long distances and onto odd shaped surfaces such as the Sydney Opera House sails. Mist and smoke from passing ferries makes the beam itself visible. This Laservision display during the recent State of Origin rugby league matches used a whopping 20 watt Argon laser. The large display is so bright that the full sportsground lighting was able to be left on for the whole display. system - that enables the display to be changed almost at will. For example, a large city Laservision diplay could be programmed to display a multiplicity of advertising messages which could be charged on a timeslot basis, just the same as TV. But interspersed with the advertising could be useful information to the passing parade of citizens; news bulletins, traffic and accident reports and so on. Where the laser billboard was visible to large numbers of motorists, as it inevitably would be, it would be possible for the local traffic or municipal authority to specify how much animation and how many changes per minute there is in the advertising. The idea behind this is that the advertising can be made less distracting to motorists in peak hour conditions. Actually, Laservision doesn't even need a flat wall on which to project a recognizable image. Since a laser beam is always in focus, it can produce an outline image on any surface, including the curved sails of the Sydney Opera House. What about the drawbacks of laser advertising on buildings? Are there any at all? Well, apart from the need to supply the power and control requirements of the laser, which we '11 get to in a moment, and the possible danger of people being injured by the laser, there aren't any real drawbacks, unless of course, you regard the advertising itself as a drawback. Is it possible to be injured by the laser? Absolutely. Laservision's 5 watt laser can lighl: a cigarette at 100 metres! If it got you in the eye, you'd be blind and that would be that. Even looking at the spot projected on a AUGUST 1990 77 Really, when you consider the above figures, high power lasers are hungry beasts but what little light they put out is coherent and that's what makes laser light so special- its concentrated beam diverges very little over long distances and it can even write on the clouds. In the future, Laservision hope to be working with solid state lasers which have much higher efficiency. Even now, there are solid state laser arrays capable of producing 5 watts but at present they can only work in the infrared region. Controlling the light fantastic This is the 3-phase power supply for Laservision's 5 watt model. Rated at 14 kilowatts, it is water cooled, as is the laser itself. nearby wall by a 5 watt laser is painful and it can set the wall smoking in a short time! So clearly, the laser can only be set in such a way that no-one is ever likely to come into contact with the beam. In fact, there are strict guidelines set down by the National Health and Medical Research Council of Australia which cover the safe use of lasers. Mind you, while the laser could light a cigarette at 100 metres and even burn a wall when focused to a stationary spot at close range, when scanning images at a distance there is no likelihood of damage to buildings. In principle, deflecting a laser beam to write a message is simple. One mirror deflects it in the X direction (ie, horizontal axis) while another mirror deflects it in the Y direction (Y axis). Continuously move both mirrors by very small amounts and the beam can be deflected extremely rapidly to produce an unbroken outline image which may be hundreds of metres wide and hundreds of metres high. Laservision's system does all this and a great deal Laser specifications Few people have ever come into contact with lasers and when they have, they have usually been small helium-neon instruments capable of putting out just a few milliwatts. On that basis, their power supply requirements have not seemed very demanding maybe a 50 watt power supply is all that is required. But when you scale up the power demands to feed a 5 watt laser, you realise just how inefficient these devices really are. Laservision commonly employs a 5 watt Argon (blue-green) or Krypton (red) laser. These are large instruments typically measuring 114cm long, 16.5cm wide and 18.6cm deep. They are heavy, weighing over 46 kilograms (102lbs). They use a 3-phase rack mounting power supply which looks reasonably impressive but it is not until you look at its power input specifications that you realise just what's involved: 40 amps per phase at 208 volts AC; that's just over 14 kilowatts! To supply that requirement from Australian 415V AC 3-phase mains supply takes a whopping transformer that weighs over 95kg! Where does all that power go'? Well, we said before that lasers are highly inefficient devices and so virtually all that power is ultimately turned into heat by the laser tube and its associated plasma coils. To get rid of the heat, the laser and the power supply must be water-cooled and in fact is fed by a substantial hose at 8.5 litres per minute. 78 SILICON CHIP This is the 5 watt Argon laser, sitting on top of its carrying case. In the future, solid state laser arrays will be much more efficient and a very small fraction of the size of this model. This view of the laser shows the two galvanometer scanners and their dichroic mirrors which are used to deflect the beam. Ordinary metallised mirrors are no good for this task as they are not sufficiently efficient as reflectors - the laser would burn a hole straight through them! Moving the mirrors While this tunnel effect looks spectacular, it is easily produced by a laser and a rotating mirror - no fancy laser scanning software is needed. more. For example, in every Laservision display (whether text, script or graphics), the image is unbroken. At no point does it start or finish - it is continuous. The control software does not reduce the apparent laser light output by blanking the laser during a retrace line from start to finish of an image; the software cleverly makes the laser spot write the image in such a way as to avoid any need for a retrace period. By doing so, they not only avoid reducing the apparent light output but they also avoid the need for the extra complication of an electronically controlled shutter. As you can imagine, the mirrors which deflect the laser beam must be controlled with extreme precision. And before we go any further we should perhaps describe the mirrors. The mirrors used to deflect the beam are not mirrors at all. They look like small pieces of glass and are, in fact, dichroic filters, similar to those used for beam splitting in colour TV cameras. At the light wavelengths for which they are designed, dichroic filters act as more efficient reflectors than conventional silvered (or aluminized) glass mirrors. This is important because low reflector efficiency quickly translates into heat rise and conventional mirrors would quickly burn out - the laser literally burns a hole right through them. The two small dichroic mirrors are each moved back and forth by devices which are referred to as galvanometer scanners. In essence, these are the same as the pointer deflection coil used in analog multimeters. In fact, they are virtually the same as the mirror galvanometer, a very precise instrument which is virtually a laboratory curiosity. Like the mirror galvanometer, these galvanometer scanners have a centre rest position and the mirror can be deflected symmetrically from each side of this centre rest position. The difference is that while mirror galvanometers were very sensitive, responding to mere microamps of current, these laser deflectors are high power devices with very fast response times. As well as having a fast response time, the : We keep it simple, · so you can look smart. ProtelEasytraxn, a fast, friendly, low-cost pr ogram for PCB design that lives up to its name. PC version $395 Macintosh® version $495. Ideal for students, hobbyists and prototype builders - a professional design system for PC's that supports multi-layer boards, including power and ground planes, up to 32 x 32 inches. Complete throughhole package includes pad-to-pad autorouter, editable ~ Protel Technology component library, metric/ in1perial grid system to 1 mi! (.001 inch) placement accuracy. Supports popular printers 2 Protel Easytrax and pen plotters, plus Gerber ®, Postscript®and N/C drill output. User files and libraries are compatible with both PC and Mac versions. So, you can get smart and take the Electronic Desi!Jn. A u tomation specialists 1· Product ofAustra ia © 1990 Protel Technology Pty Ltd affordable solution. GPO Box 204 Hobart Tasmania 7001 Australia Phone (002) 730100 (Int'l + 6102 730100) Fax (002) 730944 (Int'l+6102 730944) PC version requires XT/ AT/ 386/ 486 compatible ,vith 640K RAM ; DOS 2.0 o r later. Macintosh version re quires Mac Plus, SE o r II. Mac and M.\Cintosh are registered trade marks of Apple Compute r, Inc. Gerbe r is a registere d trademark o f Gerber Scientific , Inc. Postscript is a registered trademark of Adobe Systems, Inc. A90-S AUGUST 1990 79 galvanometer scanners have positional feedback [via separate coils) and temperature compensation so that the laser beam does not drift from its initial set-up position as the temperature changes. To provide the temperature compensation, the galvanometers have been provided with external heaters and thermocouples. The other reason for having positional feedback and temperature control is to make sure that the laser always follows the same path when scanning out a pattern - if it did not continually follow the same precise path [within a few millimetres at a distance of 1 kilometre) the image would be blurred and not as bright. In addition, the drive circuitry defines the limits of horizontal and vertical deflection of the laser beam [the scan "window"). This is an inbuilt safety feature so that even if the driving software goes awry the laser beam will not be deflected anywhere but at the target wall. The time for the laser to make one complete scan of the image is typically 20 milliseconds although it depends on how complicated the image is. Larger and more complicated images take longer to scan but once the scan frequency gets down below 20 Hertz or so, flicker begins to become a problem. Interestingly, the scan rate can be set to avoid flicker problems when the display is being recorded on film or video and the programming has time code facilities so that a laser display can be precisely choreographed into a video production schedule. 80 SILICON CHIP Laservision can project very complex images such as this one for a well known magazine. The images are vector scanned in outline and not "raster scanned" as in video technology. Note that this image is being produced in real time, direct from the digitiser tablet. Another interesting aspect of the software includes the ability to "keystone" the display so that it can be projected onto oblique roofs or for example, on the Sydney Cricket Ground during the recent State of Origin series. As well, images can be rotated, and animated to blend from one to another, expand, contract and so on. It is this ability to rapidly change images which make the Laservision display so entertaining to audiences at large entertainment venues. Apart from the power amplifiers, power supplies and other analog control circuitry, Laservision's control hardware includes a full size digital to analog control card which fits into a Toshiba T3200 laptop computer with a plasma display. It is used in conjunction with a digitiser panel for direct programming of the laser display. The photos included in this article show some of the spectacular displays which Laservision has produced. For us though, one of the most satisfying was the setup they did specially for the SILICON CHIP logo. They say there is nothing like having your name up in lights. With Laservision, that's especially true. Acknowledgement Acknowledgement: our thanks to Paul McCloskey of Laservision [Aust) Pty Ltd for his assistance in the preparation of this story and for supplying the photos. DISKS! LIFEIIME WARRANTY 0. 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Pt Moresby 25 6322 Lae 42 6246 "Recommended prices only AMATEUR RADIO By GARRY CRATT, VK2YBX The old vs. the new - we compare a vintage shortwave receiver with today's technology Ever wondered how a Collins communications receiver from the 1950s compares with a modern synthesised counterpart? Read on the answer might just surprise you. Recently, we had the opportunity to compare one of the old-time favourite receivers, made in the mid 1950s, with the standard monitor receiver in our lab, a Yaesu FRG-7700. The results of this comparison highlight the outstanding design and construction techniques used in post-war equipment, and show that these units can still represent good value for money today. Most amateurs have heard of the brand name "Collins". In the 1950s, the name was synonomous with rugged high-quality communications equipment. And the most famous of all the Collins equipment was the "S line" series of transceivers. Earlier models included the "75A" series of amateur band only receivers, and prior to that, the "51" series of receivers, which surfaced on the surplus market in the late 1960s. Unearthing a relic The particular receiver we "discovered" is the 51J4, the last in a series of five receivers, manufactured in the early 1950s. This prize was unearthed during a visit to a connoiseur's shack, where it had • I\ The Yaesu FRG-7700 is a modern shortwave receiver featuring phase-locked loop tuning, digital frequency readout and memory circuits. It has better sensitivity than the Collins 51J4 but is eclipsed in some areas. 82 SILICON CHIP been buried for the previous 10 years. We decided that it would be interesting to test the receiver to determine what advances, if any, had been made in receiver design and construction in the last 40 years. The first and most obvious observation to be made about the 51J4 is its weight and size! The unit is massive, measuring 585mm across the front panel, 265mm high and 380mm from front to rear. It's total weight is around 20kg. The unit contains 19 valves or, as the manufacturer would call them, "tubes" and the total power consumption is 85 watts. By contrast, the FRG-7700 measures 334 x 129 x 225mm (W x H x D) and weighs just 6kg. So, as far as size and weight are concerned, considerable improvements have been made to receivers since 1950! The specifications provided in the manufacturer's handbook are quite respectable, even by today's standards. One notable specification is frequency stability - the dial calibration is guaranteed to be within 300Hz at room temperature and the unit has an operating temperature range of - 20°C to + 60°C. The sensitivity is quoted as 5µ,V for 10dB S/N but our unit measured 2µ, V for the same ratio (0.5µ, V for the FRG-7700). The complete block diagram for the Collins receiver is shown .in Fig.1. The biggest difference between the two receivers is the complexity of the Yaesu PLL generator, frequency counter, and memory circuits. The Yaesu receiver has a first IF of 48MHz and a second IF of The Collins 51J4 was built like a battleship. It covers from 540kHz to 30.5MHz in 30 1MHz bands, features mechanical tuning and contains 19 valves. The unit weighs about 20kg and has a total power consumption of about 85 watts. 455kHz. Synthesised local oscillators are used to ensure good frequency stability, although the end result is only as good as the Collins unit! The Collins receiver Basically, the 51J4 is a superheterodyne unit covering 540kHz to 30.5MHz. This tuning range is covered in 30 1MHz bands. The receiver also contains AGC circuits, a noise limiter, and a lO0kHz crystal calibrator. The first IF is either 2.5MHz or 3.5MHz and depending upon which band is being received, single, double, or triple conversion may be used. To enable each 1MHz band to be tuned, a highly stabilised permeability tuned oscillator is used to heterodyne against the first IF. This oscillator is fed from its own DC regulator to ensure stability. The second IF is at 500kHz and the receiver is equipped with both .NOT[: BANDS 4-30 EV EN BANDS-INJ. fREQ=B ANO I-JO +2 ODD BANDS-INJ . l='REQ: BAND NO+~ Fig.1: block diagram of the 51J4. It features permeability tuning, mechanical filters & either single, double or triple conversion. mechanical and crystal filters at that frequency . Mechanical filters Mechanical filters are electromechanical bandpass devices whose dimensions are about one quarter the size of a cigarette packet. As shown in Fig.2, a bandpass filter consists of an input transducer, a resonant mechanical section consisting of a number of metal discs, and an output transducer. The frequency characteristics of the mechanical section give almost rectangular selectivity curves as shown in Fig. 3. An electrical signal applied to the input terminals is converted into a mechanical vibration at the input transducer by means of a process called ''magnetostriction''. This mechanical vibration travels through the resonant mechanical section to the output transducer, where it is converted again by the magnetostriction process to an electrical signal, which appears at the output terminals. In order to provide the most efficient electromechanical coupling, a small magnet in the mounting above each transducer applies a magnetic bias to the nickel transducer core. The electrical impulses then add to or subtract from this magnetic bias, causing a vibration of the filter elements which corresponds to the AUGUST 1990 83 5 I 10 I 15 I 20 I ~ 25 dB I COUPLING ROO \ MAGNETOSTRICTIVE - -------1 DRIVING ROD 30 I 35 I 40 I 45 I COIL 50 I ELECTRICAL SIGNAL (INPUT OR OUTPUT) ELECTRICAL SIGNAL (INPUT OR OUTPUT) Fig.2: inside a mechanical filter. The input signal is converted to mechanical vibration by magnetostriction and travels via a number or resonant discs to the output transducer. exciting signal. There is no mechanical motion except for the imperceptible vibration of the metal discs. Magnetostrictively driven mechanical filters have several advantages over electrical equivalents. In the region of 100-500kHz, the mechanical elements are extremely small and so a mechanical filter with better selectivity than the best of conventional IF systems can be enclosed in a package smaller than a crystal filter. In addition , the frequency response characteristics of the mechanical filter are permanent no alignment is necessary or possi- ble. Unfortunately, cost and advances in modern crystal filter performance mean that mechanical filters are rarely seen in these days. Another major drawback is that mechanical filters are limited in frequency to 500kHz or so, while quite reasonable crystal filters can be made for frequencies up to 30MHz or so. However, considering the age of such devices, their performance is unbelievable. Phasing control Another most useful feature in the 51J4 is the "phasing" control. This allows control of a variable notch filter within the IF response The circuit techniques may be ancient but they still add up to excellent performance. They sure don't make 'em like this anymore! 84 SILICO N CHIP kHz Fig.3: typical response curve of a mechanical filter. The result was excellent selectivity. curve, allowing unwanted heterodyne s from adjacent channel signals to be notched out. This feature is found only rarely in shortwave receivers and is also seldom used in amateur receivers. One of the tests we used to determine the ability of a receiver to process strong signals is called the "blocking test". For this test, we injected a signal on the desired frequency, and then injected a second interfering signal 3kHz away. The amount of interfering signal required to degrade the SINAD reading of the desired frequency by 3dB determines the receiver's ability to withstand a "blocking" signal. Fig.4 shows our test layout. Most modern receivers have rather poor performance in this area. The "fix" on these receivers, [including the FRG-7700) is to provide an attenuator which can be adjusted by the operator to minimise the effect of strong signal overload (and also receiver sensitivity). In a well designed receiver like the Collins 51J4, no attenuator is necessary due to the excellent design of the RF, IF and AGC stages. In fact, our unit exhibited a 30dB improvement over the FRG7700 in this critical area. There was one area where our vintage receiver lacked in performance and that was SSB reception. This is quite important for amateur service these days but perhaps not so in the 1950's. Fortunately, the subject of improving SSB performance was covered by the American magazine Ham Radio in their February 1978 issue. Basically, this issue detailed the modifications required to change the BFO to a product detector, and to change the AGC attack and decay time constants to allow correct reception of SSB. Some audio stage modifications are also detailed. After we implemented these recommended modifications, the "DESIRED FREQUENCY" SIGNALGENERATOR SINAD METER COLLINS 51J4 RECEIVER SIGNAL COMBINER "INTERFERING" SIGNAL GENERATOR Fig.4: the test layout used to determine a receiver's ability to withstand a "blocking" signal. The 51J4 was considerable better than the FRG-7700 in this important area. C206 5pF TD ------...11--<)DETECTDA V110A T106 ,-------------7 I !JI I,{;[ I 1 II ___ ._..... I I I I B+ I BFD PITCH I I C218 .01 12 L - - - _ _ _ _ _ _ _ _ _ _I .,. Fig.5(a): this is the original 51J4 BFO circuit. The tube is turned off by switch S112 which short circuits the screen voltage to ground. .05 TD PINS 6,7 V110A AM o--- ~-- ,, S1128 (' 5pF1 TD PIN 3 XV112A VIA C209 ----- I I TD R154 (VOLUME) I I I I I I n------xo_1.., " ' ~ _______ ~,:/_ _ __ ovI1- SJV.,. 01 5 J 1N270 TD PIN 3-""41t--\l\Mr--l-.,_-1---.----------<--- TD R171 V110B AND XV111A C205B 1-1.5 + 1M 0.1 l 100VJ Fig.5(b): the revised circuit substitutes a 6BE6 tube for the original 6BA6 to provide a product detector. The AGC attack and decay time constants are also modified as shown to allow SSB reception. receiver performed equally as well as the FRG-7700 on SSB signals. Fig.5 shows some of the necessary circuit changes. In summary, considering the age of this receiver and the techniques used, its performance is amazing. Although the sensitivity is somewhat worse than modern receivers [and this can be overcome with a good HF antenna), it outperforms modern receivers in many other respects. It's also worth noting that the price of a Collins 51J4 on the secondhand market is similar to the price of modern pre-loved Japanese receivers. If size and digital frequency readout are not of major importance and a few valves can be kept as spares, the Collins 51J4 receiver should continue to provide good performance for many years to oome. ~ A UGUST 1990 85 Deals that will make our Champ 360dpi Hi-Resolution Mouse. More squeak for your dollar! CAT ACCM If you want a superb q uality mouse that is fully MicroSoft and Mouse Systems compatible. this is 1t l The Champ Mouse is a precismn pomting device. suitable for all Mouse dnven software. including Wmdows. Word. WordPerfect. Ventura. CAD packages etc. The Champ features double the resolution of lesser rodents, with 500mrrJser: tracking. 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CGA and Hercules Graph1cs/MDA monochrome standards The VC1024 1s fitted with an addmonal 256K of display memory for up ID 1024 x 768 pixel resolution If you want the performance and flexibihty of a 386 machine without the pricetag, you need our new NEAT Chipset motherboard. It out-performs 16MHz 386SX systems costmg much more yet offers supenor flexibility The board is superbly engineered . with top quality surface mount components for the ultimate in reliability. Features : • Rechargeable battery backup on the motherboard • Clock speeds of 12 or 16MHz (0 wait state) • Page interleaved memory uses DIL (44256, 41256. 411000) or SIP memory chips. Up to 5MB of mai,1 board memory. Can be config:i:ed as any combination of DOS, Extended or Expar,ded (EMS) memory. • Shadow RAM function. System ROM and Video BIOS can be mapped to fast RAM for hghtning fast response • Expansmn slots: 16 bit x 5, 8 bit x 3 • Fast ~ Landi nark 20.5 (16MHz), 14.8 (12MHz) • Password protection in ROM • Calculator and Timer in ROM • User definable hard disk support. Drives not in the BIOS table can be entered by the user and stored m CMOS RAM. 47 disks in ROM plus a user defmable place (No. 48) (1 2MHz/0WS/0KRAM) I D RAM CA Adaptors ONLY $9.75 each ONLY$99 Memory CAT.DCAH ONLY $199 SAVE $26 CAT. DCAHF ONLY $225 SAVE $24 CAT. LA9M25F 9 pm plug to 25 pm socket CAT. LA9F25M 9 pm socket to 25 pm plug The approprratc pms connect mtemally to allow for matching of senal equipment usmg a mrxturP. of 9 pm and 25 pm connP.ctors (eg a 9 pm senal connector on "senal mouse to a 25 pm senal port on a PC) CAT MB286!2N isa A CDS ✓.l. • Suits all parnllcl pnntors 1.1 soctor mtorloavmg. usmg the latest Western D1g1wl 1006 chip sot grontly This 1s Austraha's best pnce on a top quality EGA video card And you get a FREE printer port (I/O selectable) Features include: Full compatibility with XT. AT. 386 Full 256K display memory CAT MBXCI C/\:1' DCAH (HI)[))"' CAT DCA!!F (I ID[) & m m Spood up tho chsk porformanco of your AT or 386 machmo by a factor of around NEAT Chipset PC/AT Motherboards Software allo...,vs software selection of ~esolution from 60 to 1080 dpi. Excellent tactile response and three button design are complemented by the FREE software that provides mouse support for a huge range of non-mouse driven programs A MOUSE MAT and MOUSE POCKET are also included, but stocks are limited at this pnce so order early to avoid disappointment' 1. CAT ACDS?1 CAT Lowest Price EGA card in Australia has FREE printer po!l! 1\vo cards ea n !Jc installed m a syste m and the card 1s AST Four Port/XN hard w ar e and software compatlblc Comes with full cincum e ntat1on Big savmv on curron t s tock only $175 B,g savmgs on these fully IBM Compaoble PS/2 memory ca,ds Provides up to 2MB of memory (OK fitted) on any PS/2 type computer It uses 1MB DIP type DRAMs and 1s fully compat1ble with the IBM PS/2 50/60 Memory expansion opuon Normally $299 Save only $249 Phone for details of other M1c10Channe l products JI' our C aLn logue competitors burst into tears!! ........................... QUALITY ELECTRONIC ■ TOP : soLUTIONS SYSTEMS AT : Low LOW PRICES. DON'T ■ SEffLE FOR LESS! I If you want a top quality system at a good pnce, check these : prices. Unlike others, all Electronic Solutions systems use only I top quality components from leading suppliers Top quality NEC I drives , surface mount technology mother boards, Japanese I keyswitches in the keyboard, etc etc. Don 't settle fo r less. I 80386SX/ 20MHz/VGA ■ .20MHZ/386SX system I I I I with 16 bit VGA card , VGA monitor, 1MB RAM , 1 2MB floppy, 40MB NEC hard disk, 2 serial and 2 parallel ports and genuine Microsoft MS-DOS 4 01. Normally selling for $3995. Desktop Case standard, M1rn Tower case $75 extra ■ ■ I I I I I only $2995 80286/12MHz/20MB/EGA Fast 12MHz zero wait state processor, with quality 20MB drive , 1.2MB floppy, 1MB RAM, 2 serial and 1 parallel port and genuine MS-DOS . 4,01. Normally $2395 Desktop Case standard, Mini Tower case $75 extra. : = ■ I I I I I I I I I I I I I I 1 I As the 80286 system above but with a faster 16MHz CPU Normally $3495. Mini Tower Case 1I standard. only $2696 extra with any system! External Drive Case & Controller ·· cAT CAESP The case comes complete with cable and specially designed ¼ size card that fits in your PC and will not conflict with your .. J · existing hard , ··· d isk/floppy disk controller. Perfect for fitting 5¼" or 3½" drives or tape backup externally only $199 this is it Our MBXC2 comes in at a staggering 10.9 on Nortons SI - that's 31MHz compared to 4.77MHz on your standard XT. The board is ful ly XT compatible and runs with all standard XT cards. Speed is switchable between standard 4.77MHz and turbo speed. Up to 1MB of RAM can be fitted on-board. For even faster operation, the memory above 640K can be used as "shadow RAM" for speeding up BIOS operations or as a RAM d isk. The board provides software selection of wait-state. Performance Index I -:_~ VTEK .. - · '°='I. DATA COMMUl'.ICATI ONS Deals on Avtek Modems . Save while stocks last! NEW! MegaMoclem 1234. CAT MM1 234 (OK RAM fitted) ONLY $499 only $249.00 If you want the fastest XT on planet Earth, •••••••••••••••••••••••••• 12MHzPC/AT This high performance PC/AT motherboard has everything I Others charge the same for boards wi th nothmgl I This top 4ualrty motherboard uses state-of-the-art VLSI technology and s urface mount design for best performance and reilabrbty. Don 't accept Jessi • 12MHz zero wait-s tate CPU (15 9 MHz Land mark speed rating) • Up to 1MB of RAM on the mothrrboard (OK fitted ) B0nS or 120nS RAM can be fitted • 4 x 16 brt and 4 x 8 brt expansion slots • 2 senal and 1 parallel port built m. rncludmg cabling • Rechargeable on-board battery backup CAT CAMTP This brand new Tower case rs perfect for any XT AT or 386 machine. Superb styling and heavy duty construction make this an open and shut easer A flip down smoked perspex cover protects the drives and power switch from accidental knocks . The power supply is a heavy duty 230W output unit Don' t settle for Jess i Features include: • Drive bays for 3 x 51,1,i· FDDs or HDDs, two 3½" FDDs and one 3½" HDD. • 4 LED indicators and Turbo switch • MHz display (2 settings to tie in with "normal" and "turbo" modes) • Heavy 1 Ll4mm steel construction • Dimensions: 77/s'' x 16" x 15¾" CAT CAESMP This quality case , includes a 5V/12V i power supply and , has standard SCSI : connectors and : cable. Just fit a SCSI : drive and you 're in · business. The World's fastest XT Turbo 31MHz XT Motherboard cAT Msx c2 ONLY $225 I 80386/20MHz/ 2MBNGA I Fast fully 80386 system with 2MB of RAM, 1.2MB floppy, 40MB NEC hard disk, 16 bit VGA cmd I and Monitor. Professional Style Mini Tower case. I Normally $5295. Mini Tower Case standard I only $3795 1 ao386 /25MHz I As the above 80386 system but with 25MHz I CPU. Normally $5495. Mini Tower Case standard. I only $3995 I Large Tower Case $150 cAT Ms2s512v Case ONLY $399.00 1 80286116MHz Motherboard with the lot!! SCSI Drive Cases Introductory Special only $2<?,95 I "Professional Look" ■ Vertical Internal or External, includes Software and Cable. 300/300, 1200/1200, 1200n5 and 2400/2400 baud only $399 MegaModem 24 CAT MM24 300/300, 1200/1200, 2400/2400 baud . Inc . cable and Software. only $349 Norton's SI, V-4.0 2 3 4 5 7 8 9 10 11 MBXC2 IBM XT IBM PS2 Model 30 10 MHz XT IBM AT ·············-·-···············-Electronic Solutions Box 426 Gladesville 2111 Phone (02) 906 6666 Fax (02) 906 5222 We accept Bankcard, Mastercard & VISA Mail orders our specialty. Freight on smaller items is now $9 00 + $250 P&P • A ll prices include sales tax • All products carry a 14 day money back guarantee (software and hard disks excepted) • All Motherboard carry a full 12 month warran ty • All products carry a fu ll 3 month warranty • All cards come with full documentation • Rin g fo r quantity discounts and tax free prices Owing 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 I I I . REMOTE CONTROL By BOB YOUNG Bluff body design & automotive aerodynamics Having concluded our discussion on the aerodynamics of full size aircraft, we will now look at how those principles apply to motor vehicles. This should be of interest to the R/C model car enthusiast. As the speed of a road vehicle increases, the benefits of aerodynamic design become more and more important, particularly when combined with the spiralling costs of fuel and the fact that petroleum is a finite resource. To give an example of the savings involved, in the UK alone it has been estimated that reducing freight vehicle drag by 10% would result in a fuel saving of 300,000 tonnes per year. Keeping in mind our earlier discussion on drag, it is obvious that once again our old enemy "velocity squared" is in there stirr- ~ -==== ing up trouble as usual. The ramifications of the vZ problem when applied to the Very Fast Train (SILICON CHIP, March 1990), for example, are extensive. Not only does drag increase with vZ but lift increases also. This could result in loss of traction and possibly even contribute to the train leaving the rails under certain adverse conditions. As discussed in previous columns, fuselage lift for aircraft can be quite considerable and exactly the same principles apply to ground vehicles, which if not very carefully designed cease to be ground BASE - PRESSURf/ --l--o.76 l'\J'45• 15 L / STING ALL DIMENSIONS IN mm Fig.t(a): experimental wind tunnel arrangement for determining the drag coefficient of two discs mounted in tandem. The resulting drag is much lower (within limits) than for a single disc. 88 SILCON CHIP vehicles and become airborne. This happened to the Stanley Steamer in a very early speed run on Daytona Beach. It became airborne at 150km/h and crashed. Vehicle aerodynamics Vehicle aerodynamics involve all sorts of components. The overall flow field consists of streamlines, wakes, vortices, interference with the road surface and rotating wheels, surface pressures, and noise and rain effects. These must all be taken into account. Stability at high speed, particularly the response to side winds (yaw) and gusts can be deficient, especially in low slung streamlined sports cars. An adequate flow of cooling air is needed to remove heat from the radiator. Intakes for internal ventilation, heating or air conditioning have to be placed where the dynamic air pressure is favourable and will not result in exhaust fumes being drawn into the vehicle. A particular problem involving heavy vehicles is the generation of large sheets of spray in rain. This creates a potential danger for overtaking cars, especially in dark and foggy conditions. Reducing air resistance and adding fairings helps to minimise this problem, as well as making the vehicle more fuel efficient. All of these problems respond to the vZ law. Even the windscreen wipers get into a frenzy at high speeds and will lift off the windscreen in some vehicles. Thus, we see that the science of aerodynamics is very important to all citizens of the modern world and affects us greatly, in matters as diverse as our methods of travel, safety and pocket. \J I I 1.4 I I I I I I 0, 1 02 = , .o 1.2 02 = 70 mm I I Bluff Body design Vehicle design is generally lumped under the scientific title of "Bluff Body, Ground Proximity" aerodynamics. This is a quaint way of saying that the space inside the vehicle is more valuable than the space devoted to streamlining. To understand this, we must now move on to some of the very interesting aspects of Bluff Body aerodynamics. To begin, drag, not lift is the major item of interest in vehicle aerodynamics. Not only is lift not required, it is positively dangerous, as we have already noted. Now the measure of aerodynamic cleanliness is the "Coefficient of Drag" (Cd) and is in effect a comparison of the drag of the body under examination to the drag of a flat disc of equal cross sectional area. This flat disc is said to have a Cd of 1.00. The usual figure quoted for Cd on modern cars runs around 0.3 to 0.35, which simply means that a typical car has about one third of the drag of a flat disc with area equal to the vehicle's frontal area. Referring back to airfoil theory we can see that an airfoil can have a Cd as low as .01. Cars are a long way from this figure due to the ratio of their length to cross sectional area. A good rule of thumb for the ideal streamline shape is a ratio of 16:1. Thus, a vehicle with a frontal area of 2 square metres should be 32 metres long. Plainly, this is impossible. To overcome this problem, we have the science of "Bluff Body aerodynamics". The really interesting thing about air is that in essence it is quite capable of helping itself but is hindered by a finite response time of 335m/s (ie, the velocity of sound in air). Bluff Body aerodynamics relies heavily upon this ability of air to help streamline itself. Transonic aerodynamics is the art of dealing with air which can no longer help itself. I I I I I ,., I I I I I I 1.0 I I 0 .9 Fig.l(b): the graph plots the drag coefficient vs. gap length (L) for two discs of equal diameter. The Co is a minimum at L/D2 = 1.55. To explain, let us examine two very interesting and curious phenomena, the first being a sphere which has a minus drag coefficient. This means that it generates a small amount of thrust from its own drag. At first glance, this statement indicates that we should all be travelling in spherical cars and aircraft but the truth is that the gain is so small that any protrusions such as wheels destroy any benefits. It is also not a very practical shape to work with. It is very poor directionally and easily blown off course by cross winds, due to the lift and thrust generated on the sides. The early aerial bombs were spherical and were difficult to aim accurately as a result. The shape of the modern bomb is no accident. The second curiosity is the "two disc" pair. This arrangement is simply two discs in tandem (Fig.la) mounted in such a way that the separation between them is variable. Fig.1 b shows that the drag coefficient of the pair is related to the ratio of their diameters and the distance between them and is much lower than for a single disc. The reason for this is simply that air will form its own streamlining from eddy currents. Here then is the saving grace for the modern motor car and the core facet of Bluff Body design. The trick is to get the air to do the streamlining for you. Figs.Za & Zb illustrate this quite clearly and show the Cd for squareback and fastback vehicles. By setting up the correct conditions for eddy currents behind the car, it is possible to simulate a full streamline flow of near ideal proportions. By pumping air into this zone or bleeding air out, quite a low Cd can be achieved. Much work is being done in this area to create the ideal low drag motor vehicle. Modern designs In the early days, the designers of streamlined cars attempted to create a shape that was like a halfteardrop with a very rounded front and a gently tapered rear. However, this had to be impractically long, as noted, to give any worthwhile drag reduction and was often directionally unstable. Almost all moderately sized cars now have a distinctly short afterbody and these are characterised by definite f IXl.1! ~s:~: ,s_f~'>)Jl>> . . .,: Fig.2(a): by setting up the correct eddy current conditions behind a car, the air will form a streamlined flow and quite a low drag coefficient (Co) can be achieved. AUGUST 1990 89 o· 10° 20° 30° so• SQUAREBACK-TYPE FLOW FIELD. Fig.2(b): the drag coefficient is extremely sensitive to the angle of the back window. The lower drag of the fastback is one reason for the increasing popularity of this style of vehicle. wake flows and vortices. Two types of afterbody flows are shown in Fig.3. The recirculating bubble or spiral vortices determine the drag and stability. They also determine how much of the dirt thrown up by the rear wheels is deposited onto the rear window and body. The drag coefficient is extremely sensitive to the angle of the back window as in Fig.2b. The lower drag of the fastback is marked and accounts for this increasingly popular although rather angular shape. Air does not like abrupt changes in direction and sharp corners increase drag tremendously. The early Volkswagen Kombi of the 1960s is a good example of the advantages to be gained from wind tunnel testing. The original design had sharp front edges and wool tufts placed along the sides showed that the airflow completely broke away and was turbulent. Even quite modest rounding of the front edges and corners streamlined the airflow and reduced the drag by 40%. The important point to remember is that air is limited to a response time of 335 metres per second. This is quite slow and so we have to adopt special techniques to achieve streamlining. We do this by design90 SILICON CHIP ing our shapes so that the airflow does not have to make abrupt changes in direction. Some indication of the progress being made in drag reduction of vehicles can be gained from the Cd figures over the years. In the 1920s, average American car Cds were 0.7, falling to 0.5 by 1940. In Europe, the average Cd for 86 popular makes was as high as 0.46 even in the 1970s, the actual range of values being 0.37-0.52. Reynolds numbers Great care is needed in quoting and interpreting drag coefficients for motor cars. Tests done by General Motors on a 1/4-scale fastback gave a Cd of 0.27 at a Reynolds number of 700,000, which decreased to 0.23 at R = 2,000,000. Often, tunnel models are simple shapes that don't include all the practical details. The Reynolds number is far too complex in concept for a full explanation here but briefly, Reynolds in 1883 combined a host of factors influencing surface flow. These included form, waviness or roughness, speed of the mainstream, distance over which the flow has passed on the surface, and the ratio of density to viscosity of the fluid. He combined these into a single figure derived from the following formula: Re = Density/Viscosity x Velocity x Length. As a general rule, the higher the Reynolds number the more efficient the result. It is here that we see the problems arising in model aircraft with tapered, high aspect ratio wings such as in scale models. For any given airspeed, the Reynolds number will always be lower at the tip than at the root. When combined with the high angle of attack at landing and tip vortices, there is a great danger of the tip stalling first , causing the wing to drop and the model to fall into a spin. For this reason, washout (reduced angle of attack) at the tips is a bsolutely essential on this type of model. Conflicting requirements The skill of the vehicle designer is also shown in the way he blends the conflicting aerodynamic requirements into a working motor car. A good example of this is the Lotus Elite GT 4-seater. It is low and wide and the top of the windscreen is more than half way towards the tail. The curved wedge-like forebody was kept low by having retractable headlights and a canted engine block (the resulting aerodynamic drag power is only 30kW at 160km/h). A serious consequence of this, found in experimental models, was a large upward lift on the curved forebody which decreased adhesion of the front wheels. This would have made it dangerous in crosswinds. The cure was to fit a wide scoop under the front of the engine. This collected high speed air and passed it through a shallow, wide radiator so that the retarded air was ejected into the boundary layer on the top of the curved forebody, thereby breaking the lift suction. In this way, drag, stability, lift and cooling airflows were all combined successfully. Lift reducing traction and steering is a serious problem for vehicle designers and many solutions have been tried. The large inverted airfoil seen on some of the dirt track · racers is, to my mind, the least elegant. While it does generate a STATIC RAM 62256 4425 2764 4116-5 $19.95 $18.00 $3. 00 $1.25 41256 $5.00 4464 $6.00 2114 -2 $1.00 4164-12 x 9 SIMM Modules $12. 95 ea SPEAKERS 12 " 100 Watt Woofer 12" 30 Watt Woofer 1O" 25 Watt Woofer 8" 20 Watt Woofer $59.95 $42 .50 $25.50 $18 .50 ea ea ea ea CAPACITORS 10,000 nf 40 Volt DIODES 4002 1A $4 .50 ea $5.50/100 $65.00 ea INFARED DETECTORS Limited Quantity, 40' to 80' range, adjustable. MICROWAVE OSCILLATORS VA221 B 7.255 - 7.555 Ge V220D 6.575 - 6.875 Ge $25.00 ea NICAD BATTERIES Fig.3: the afterbody airflows for two different vehicles. The recirculating vortices for the lower model determine the drag and how much of the dirt thrown up by the wheels is deposited on the back of the vehicle. In practice, the drag coefficient is extremely sensitive to the angle of the rear window (see Fig.2b). downward force on the wheels, it creates a lot of drag and therefore is somewhat self defeating. A more elegant approach is to convert the underside of the vehicle into a venturi by fitting a fairing. This serves a twofold purpose. First, it eliminates underbody drag from the rough underside which can amount to as much as 5 o/o of the total drag. Secondly, in keeping with Bernoulli's Theorem, it generates a low pressure area under the vehicle and thus provides a downward force on the tyres. This could be an important point in R/C model cars where the light axle loadings result in very low footprint pressures. Traction in a model car is all important and much care is required in selecting the correct tyres for the conditions under which the car is being raced. Again in electric racing cars, cooling air forced over the motor batteries will help improve battery efficiency and life. See you next month. ~ D Size 1.2V 4Ah AA 500mAh $23.00 pair $5.95 pair STEPDOWN TRANSFORMERS 240 Volt to 110 Volt 1OOvAh 250vAh TELECOM Microphone Inserts Double Adaptors $89.95 $29.95 .95c ea $1.95 ea CANNON PLUG and SOCKET 5 pin $8.00 ea TRIMPOTS 50k 1 O Turn DISK BOXES 4 for 1.00 5.25" Holds 100 3.5 " Holds 8Q $13 .50 ea $13 .50 ea IEC Filter Socket with Fuse DB25 Male and Female DB25 Male PCB mount JIFFY BOX with METAL LID 130mm x 68mm x 41 mm PL 15 40Va $4.50 ea .85c ea .85c ea $1.70 ea 10 for $15.00 $12.50 ea Low Profile Transformers ULTRA MINIATURE RELAY 12V DPST $2.50 ea 700 ohm Resistance 14mm x 10mm x 9mm MINI MICRO SWITCH SPDT .95c ea 20mm x 10mm x 6mm PCB TOSHIBA LITHIUM BATTERY .I.E...;. r.at;■f..fffi RCS Radio Pty Ltd is the only company which manufactures and sells every PCB [, front panel published in SILI CO N CHIP. ET I and EA. 651 Forest Road, Bexley, NSW 2207. Phone (02) 587 3491. 2032 $1.50 ea Shop 30, Patrick St, Central Plaza, BLACKTOWN, NSW 2148 Tele: (02) 621 1494 Mon-Wed, Fri 9-5.30 ,Thurs 9-8pm, Sat 9-3pm AUGUST 1990 91 (~;~ ~~~~~;~~~;~~ JAYCAR ELECTRONiCSJAYCAR ELECTR ONICSJAYCAR ELECTRONICSJAYCAR ELECTRON ICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRON ICSJAYCAH tLtC I HON /CA11 ELECTRONICS JAYCAR ELECTRONICSJAYCAR ELECTRONI CSJAYCAR ELECTRON ICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRON /CAR ELECTRONICS JAYCAR ELECTRON ICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRON /CAR ELECTRONICS JAYCAR ELECTRON ICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRON ICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRON (CAR ELECTRONICS JAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAl1 ELECTRON ELECTR ELECfll ELECHl ELECTl1 ELEC fR ELECTR ELECTR ELECTR ELECTR ELECTR ::C however, some minor faults with these units. edges of panel holes i.e. cut outs. Designed to ELECTR • e atural' units are supplied with silver alumanised front ·panels instead of suit panel thickness of 1mm - 1.6mm. The strip ELEC711 \ \ the standard specification anodised. • Similarly the 'Black' unit front panels are black powdercoat can easily be cut to length with a sharp knife or ELECTR FLECTR ::: instead of Black anodised. • Some top panel screw holes are misaligned. • The natural cabinets have scissors. ELECTR black side/top and bottom panels . 1 metre pack. ELECTR Apart from these minor points, the cabinets are perfect and all units confirm to lnternatinal Rack standard§ Cat. HP-0730 ELECTR Cat No Description Normal Price ~~~e Price 61_ ·ELEC"IR ELECTR HB-5511 Natural 44mm ELECTR ELECTR HB-5513 Natural 88mm ~ -- -- - - - - - ---1 ELECTR HB-5515 Natural 132mm ELEC111 ~ j HB-5510 Black 44mm ELECTR HB-5512 Black 88mm ELECTR ELECTR HB-5512 Black 132mm ELECTR ELECTR ELECTR ELECTR he same price. Quality TES ELECTR } Brand new model with more lea Features include: ELECTR ELECTR •• • 3.5 digit LCD display ELECTR ( • Peak hold This great product utilises a El ECTR passive infra red detector which ELECTR ··• • Data hold controls 240V lights to illuminate •• • AC current lOmA to 1000 ELECTR • AC voltage lOOmV to 750V at night when a person comes ELECTR • DC voltage 1V to 1000V within range A typical example ELECTK • Resistance lOOMn to 20kQ would be on a verandah. Simply ELECTR • Frequency counter 1OHz to 2kHz replace the old light switch ELECTR ELECTR Continuity check< 1oon with audio t (outside one) with the Thromatic. ELECTR Diode check When someone walkes within range (up to 15mt away) the verandah is lit up for them for a ELECTR Multimeter leads suppplied period of 5 seconds to 10 minutes, or more. ELEClR Unique one hand operation Features: • Fully automatic compact design • Security- keep intruders away • On/Off/Auto ELECTR Quality case supplied master switch on unit• Safety- no more groping in the dark ELECTR at. OM-1570 Suitable for entrances, porches, patios: stairways, garages, basements, hallways, closets, ELECTR ELECTR attics, storerooms, warehouses, workshops etc. ELECTR Up until now this type of product has been around $100 or more. Jaycar has now directly ELECTR :::::::::··-··· ··· · ·· · ··. . ..... ....... . . sourced this product, which effectively cuts out the middl e man saving you money. ELECTR $30 over previous models ELECTR ELECTR Cat. LA-5128 ELECTR We are all becoming aware that lightning in storms can severly damage sensitive ELECTR electronic equipment connected to 'phone lines. Voltage spikes on phone lines are the ELECTR ELECTR most common reason why FAX machines, answering machines. modems. cordless 'phones ELECTll etc., are damaged. Induced voltage spikes on telephone lines can be unbelievably high! Revolutionises panel and sheet cutting. Ideal for making square/rectangular holes in plastic ELECm The best way to protect 'phone equipment during a storm is to actually~ the panels and boxes for switches, LED displays etc. ELECTl1 Panel cutter is ideal for: • Plastic panels and sheets • Building materials made of urethane, appliance from the wall socket. This is sometimes not possible of course. ELECTl1 polyethylene, nylon, vinyl-chloride, Plywood, rubber sheets, leather, mat boards etc Soft thin The next best thing is to instal a device between the Telecom line and your expensive ELECTR metallic sheets made of aluminium, lead, silver etc. equipment to protect the equipment from spikes. The big problem with such a filter is that ELECTR This is a quality tool make in Japan, which will last for years. Replacement blades will be owing to the magnitude of the voltage spikes no practical filter could b e ~ to ELECTR ELECTR available. Actual tool length 120mm. Supplied with three blades 1 x 5mm and 2 x 10mm catch~ every time. ELECTR diameter. The Jaycar Telephone Line Filter attenuates the enormous bulk of line spikes whilst ELECTR Cat.TH-1940 remaining effectively transparent to the audio band used by modems. FAX machines, etc., ELECTR A number of Telecom grade spike attenuators are used including a quality German ELECTFl Siemens gas arrester. The big factor in the efficiency of this filter, however. is earth ELECTR impedance. This filter must be connected to earth and the lower the impedance between ELECTR ELECTR the unit and earth the better the filter works. The filter plugs into a Telecom socket and a ELECTR standard 240V mains socket. (The mains earth is the only connection used). ELECTR We cannot guarantee that this filter will solve lightning induced telephone line spikes ELECTR destroying your equipment. Some things (like the impedance of your earth system) are ELECTR C~ fB~ !n! :n!~ totally beyond our control. We can say, however, that this device will give your equipment ELECTR 2nf, 20nf, 200nf, 2uf, 20uf, 200uf. a reasonable chance of survival in a storm. ELECTR Inductance range: We are so confident of this product that we are quite hapP\f for you to use the unit for one ELFCTl1 2mH, 20mH, 20'.lmH, 2H, 20H. month without obligation. If you are not happy with this product in any way return the unit ELECTl1 A top quality unit and this month at a low low price. ELECTR in its original condition along with your receipt for a full refund. ELECTR Don't miss out. • Protect your expensive telephone, etc., equipment from storm damage ELECrn • Transparent to normal communications .I ' -- 1 Normally $189 ELECTR • lnstal in minutes · ·I, • ELECTR ·¼.: ELECTR ELECTR Cat. OM-1575 ELECTR ELECTR ELECTl1 ELECTRO ELECTflO Ail used in our 8002 mixer. ELECTR Save a fortune over normal prices. High qualtiy 1/04mm switchboard wire made in Australia Overall S1Ze 46(W) x 45(H)mm ::LECTRO Meter Size 44(W) x 25{H)mm by Pirelli Cables. Cable is insulated with a two colour system, and many different colours are ::LEClHO Yellow background with words ' available. If ordering more than one roll please ask for different colours. Ideal for breadboard cLECTRO "REC LEVEL· on meter jumper wires. Supplied on metal reels 250mt length. : LECfRO FSD 400uA. Coil 875 ohms. : LECTRO 'CAl1 [ Lr Cat. WH-3027 Cat. QP-5058WAS $9.95 'CAl1 ELI r;~ r ..I. .. ;;;;h , i ~;~, ~ ~o o ; ;; ~ ~ ~ !' o ~ , !~,!~J,~!:1,?!!'!...,. $1. 95 $65,00 $75,00 $90,00 $65,00 $85,00 $95.00 39.95 ~~-66 35.00 39:95 49,95 59,00 35:oo ~ " " ' : ,,,,,.. 45,00 ~ 55,00 ~§-~~ r;;.~~__ " ' l l _• - - - - , ., , __ __ , ,, , , , • •,,. • .,i1 • i Thromatic Security Sensor --- FAX - PHONE · MODEM LINE PROTECTOR PLEASE READ THIS ONLY $69.50-SAVE ~ i~-i t~ I ~ ~~:~~ eter 100 AMP AC (gt A, $16.95. roigital L/C Meter :! NOW ONLY $139 Save An Amazing $50 Single Core Hook-up Wire ONLY $4.95 • 250mt reel 'CAR 'CAR 'CAR 'CAR 'CAR EL r _ __ ____ _ _ __ ELl:CTRONICS JAYCAR ELECTRONICSJAYCAR ELECTRONICS JAYCAl1 ELECTRONICSJAYCAR ELECTf10NICS JAYCAR ELECTRON ICSJAYCAR ELECT!lONI CS JAYCAR ELECTRON ICSJAYCAR 3 VU Meter Bargain _ ________ __ ___ _ - -- ------··· ··--··· · ·· -- · "" ELECTRON ICSJAYCAFl ELECTRONICSJAYCAR Ell CT110NICSJAYCAR ELECTRON ICSJAYCAR ELECTRON ICSJ/\ YCAR ELECTRONICSJAYCAR ELECTRON ICSJAYCAR ELECTl10NICSJAYCAR ELECTRONICSJAYCAR ELEC TR ONICSJAYCAR ELECTRON ICSJAYCAR ELECTRONICSJAYCAll NOW $ 4 .95 each '• '· " •" ·-· ,.-·.,. ... .,, ,._" _,, ,_ ., , _ __, ___ ,,.,,,,_ , ,, _.,,_ u. __ _ , , EL[CTflONICSJAYCAF1 LLl: Cll1 0 NICSJ/\YCAR LLECTl10NIC SJA YCAR [ LE CTflONICSJAYCAR ELECTl10NICSJAYCAli l:LtCI HONICSJAYCAR ELECl 110NICSJAYCA11 ELFCTllON ICSJAYCAfl ELECTllON ICSJAYCAl1 El f-ClHONICSJAYCAl1 FLFClllON ICSJAYC/\11 1:1.LC I 110NICSJA YCAR " , .':.:ll lO N FI f-C HlON F L [ C 1110N r L f C IHON FI FC TRON -· . ELECTRONICSJAYCAR ELECTRONI CSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR tltC I HONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRO NICSJAYCAR ELECTRONICSJAYCAR ELECTRON ICSJAYCAR ELECTRON ICSJAYCAR ELEC TRON ICSJAYCAR ELECTRONICSJAYCAR ELECTRON ICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRON ICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR --- - .. ·- ···~~ - -· . ELECTRONICS JAYCAR ELEC ELECTRONICS JAYCAR ELEC ELECTRONICSJAYCAR ELEC ELECTRONICSJAYCAR ELEC ELECTRONICSJAYCAR ELEC TR JAYCAR ELEC .R ELEC .R ELEC ,R ELEC ,R ELEC Features ,R ELEC • Full electronic operation (FET) ,R ELEC Here's what you get: • 4 slotted bits • 3 Phillips bits • 9 hex bits • 3 Robertson \R ELEC • 12A DC & ACcurrent ranges bits• 3 Posidrive bits • 7 Toll( bits • 4 1/4' Star sockets • 7 metric sockets • 7 \R ELEC • High input impedance imperial sockets • 1 x 1/4' drive socket adaptor • 1 x 4' extension bar • Ratchet IR ELEC • Polarity reverse witch driver. \R ELEC • Safety test leads And all this lot is housed in a tough durable metal case. IR ELEC • Zero ohms adjust IR ELEC Cat TD-2002 ................................ • Mirrored meter dial IR ELEC BACK IN STOCK • Tilt stand IR ELEC • Fuse protected IR ELEC IR ELEC \ = • Working indicator IR ELEG T Cat OM-1050 IR ELEG Swann brand. Orange kn • • Was$89.95 IR ELEC out for off. 15,000uF 40V Can IR ELEC' Rated at 12 volt 16 amps IR ELEG Normally about $25 ea Ct. SP-0762 \ SAVE $10 \R ELEG Cat. RU-6714 Was$2.95 ···· ······ ··· ··· ··· ······ ··········· · I R ELEG IR ELEG ea IR ELEC' IR ELEC IR ELEC 4 dual element detection zones in three layers • IR ELEC. ide angle 90° mul ti layer coverage • IR ELEc· :j Contains motor, brass cog, gearbox housing and all other Contains approximately 3kg of assorted electronic goodies• 2 metre range · IR ELEC' \R ELEc· } parts to make various combinations of motor from 2rpm to 'JUNK' if you like, but all brand new components etc. Ideal to peration voltage 7.5 · 15V DC IR ELEC' / 1150. Works from 1.5 · 4.5V DC. Depending on load fill up your junk box. amper protected IR ELEC' Unfortunately due to the massive weight P&P is normal rates ED indication ':: drawsfrom IR ELEc· plus $5 elay output IR ELEC. Cat. X8·9000 ••, ~~-:~a%~ue for IR ELEC. ormally ,, full details. . • IR ELEC. 69.95 \ Cat. YG-2712 , ' IR ELEC' AVE $10 IR ELEC" 0 UGUST IR ELEC' ::: IR ELEC' :::., 0 IR ELEC' IRELEC' Don't miss this one. Ideal for parts If, ELEC 1 220V 50hz primary 1- no lead or plug supplied IR ELEC' Secondarys • 16V AC at BOOmA IR ELEC, · 9V AC at 1.5AMP IR ELECl Lead length 1.7mt long terminated in a ::::: IR ELECl strange plug ) IR ELECl A large transformer ideally suited to computer power Supplied in a maxi box style. Measures 75 (WI x 85 (L) x 60 .) I R ELECl Over 27,000 (YES. TWENTY SEVEN THOUSAND) (H)mm supplies. Size 115 (L) x 10 (WI x 86 (HI mm. IR ELECl American, British, European Primary IR ELECl & Japanese transistors IR ELECl 2 x 120 V 50hz (240 V) listed with comprehensive IR ELECl 1 x 110V IR ELECl electrical, mechanical Secondary IR ELECl specifications, lead 16 V Regulated to+ 12V DC 5A IR ELECl connections diagrams, Cat No. MA 2618 16 V Regulated to -12 V DC 5A IR ELECl manufacturers namesand 9.3V Regulated to 5 V DC 5.7A I R ELECl recommended substitutes. \R ELECl Cat. BM-4554 IR ELECl These transformers would normally cost about $80 each. IR ELECl We have a limited quantity available for only $30 each. = IR ELECl I R ELECl IR ELECl Simply insert your cables and crimp with a pair of pliers. Nylon IR ELECl Cat. MM-2040 insulated casing. Pack of 8 pieces. IR ELECl Due to huge weight mail order customers add $8 extra to IR ELECl Cat. HP-1210 normal P& Pcharges. \R ELECl IR ELECl \R ELECl \R ELECl Importers distress, your gai n! mm. \R ELECl 220mm long, yellow handles, super high quality. Normal trade Primary \R ELECl price is $35.04 including tax. 2 x 120 V 50hz (240 VI • 1 x \R ELECl Stock up now. Well under 1/2 normal~ rice. . \R ELECl Cat. TH-1875 110 V • Secondary 10.5V 3A SIZE 1 505 x 205mm Cat. HP-9522 \R ELECl 16V3A \R ELECl \R ELECl ) SIZE 2 400 x 170mm Cat. HP-9523 . \ R ELECl Limited quantity available \R ELECl \R ELECl x 90mm Cat HP-a<i24 \R ELECl Mail orders add $4 extra P & P. Cat. MM-2045 \R ELECl \ R ELECl \R ELECl TURNYOUR \R ELECl SURPLUS STOCK \R ELECl INTOCASH!! These batteries are encased in a black plastic housing which measures 30 (L) x 16 (W) x 19 (H) mm. They were removed from \R ELECl Jaycar will purchase your / \R ELECl printed circuit boards by simply cutting of the PC terminals so to use you would need to break open the plastic case. Inside are surplus stocks of components ( IR ELECl An amazing 3000 MCD two 1.2 V cells. So purchase 4 of these. remove 1 cell and you have an 8.2 V (9V 216 type) battery for only $4, not about $20. and equipment. We are / \R ELECl of brightness in a LED! Ideal for Hobbyists. experimenters. etc. continually on the lookout for =·· \R ELECl BARGAIN LED PACK Lights up red, clear to To buy these today they would cost about $13 ea. sources of prime quality \R ELECl look at. 100 assorted LED's 5mm, 3mm, rectangular merchandise. \R ELECl plus others. CALL MARK \R ELECl Normal value about $35 \R ELECl HARRIS OR Cat. ZD-1696 \R ELECl BRUCE ROUTLEY \R FLECl $3,65 Cat.ZD -1796 NOW ON (02) 747 \H EL[Cl \. Cat. SB-2470 2022 \R ELECl JAYC R ELECl JA'tCAH ELECrnON ICSJAYCAR ELECTRONICSJAYCAR ELEClRONICSJAYCAH ELECTRONICSJAYCAR ELECTRON ICSJAYCAR ELECTRONICSJAYCAR ELECTllONICSJAYCAR ELECTRONICS JAYCAR ELECl JAYCAR ELECTRONICSJAYCAR ELECTRON ICSJAYCAR ELECTf10NICSJAYCAR ELECl RONICSJAYCAR ELECrnONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICS JAYCAH ELECl JAYC/\R ELECTRON ICSJAYCAR ELECTRONICSJAYCAR ELECTRONI CSJAYCAR ELECTRON ICSJAYCAR ELECrnON ICSJAYCAR ELECTRONICSJAYCAR ELECTllONICSJAYCAR ELECTHON ICS JAYCAR ELECl 1/\Yr/\n FI FrT11rnJ1rs. 111vr An FI FrnlnNl/"..S.1/\YC/\'1 FI FrrnnNI C.S.11\YCAA FI F/".Trl()N l/".S. IAYrAn FI F/". TR()Nl /".S. IAYCAA FI FCTR()N l/".S.IAYr.AR FI Fr.TnnN1r.s IAYCAR FI Fr'.TRnN1 r sJAYCAR EL[Cl 0 an , vM" LLLv, nv,. ,v00M, vMn CLCv, r,v,-,vvaA fvAH cLcL I HVN l \,tiJA Yt;AK S JAYCAR S JAYCAR S JAYCAR S JAYCAR s JAYCAR "so PIECE RATCHET SCRWDRIVER SOCKET SET ~~~~ $29.95 Philips Computer Capacitor Bargain , ONLY $8.95 NOW $1 \:;pN ~ ' NOW $79.95 assive Infra Red etector Sale 4.95 . • , $18.95 EXPERIMENTORS PLUG PACK BARGAIN Ferguson Transformer Bargains PF-4725 NLY 59.95 OWERS IN TRAN SISTO 1-9 $5.95 10-49$5.50 50-99$4.95 100 +$4.50 $39.95 NOW AVAILABLE A bargain at $30 each EASY CRIMP WIRE CONNECTOR PF-4766 $1.Scb:I) ~ ·•·=·~·;;= ~·-:•.Q·~;;·~;;·· Electricians Pliers Sale PHENOLIC PC BOARD Normally $70 ea Only $20 each ] $3.60 ( $2.40 , Ji\ $~E-~sgi ~ VARTA BATTERY MADNESS 5mm3000 MCD LED VARTA 2.4 V 100mA/H Ni-CAD ONLY $1 each 10+ .90~ each 100+ . 75~ each ONLVS12.95 ONLY $8.95 ONLY $3.9510+ - ·• • 3JAYCAR ELECTRONICS JAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTF 3JAYCAR ELECTRONIC S JAYCAR ELECTRONICSJAYCA R ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTF 3JA YCAR ELECTRONICS JAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTF 3JAYCAR ELECTRONICS JAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTF 3JAYCAR ELECTRONICS JAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTF1ONICSJAYCAR ELECTRONICSJAYCAR ELECTF :AR ELECT - . .. - . --~ :AR ELECTI :AR ELECT :AR ELECT :AR ELECT :AR ELECT Vertical format. Power handling 15-20 watts. About 80 Grab em while you can. This won't be repeated. Size :AR ELECT watts system power. The potentiometers can be removed :AR ELECTF 40mm high 30mm diameter. • · which makes them ideal replacements for blown ones. by Mike Tooley :AR ELECTF This book is an invaluable source of information of everyday :AR ELECT 1O+ $2.00 each ·- · · - -· relevance in the world of electronics. It contains not only :AR ELECT Cat. RU-6730 NOW ONLY 10+ $2 Cat AC-1 684 sections which deal with the essential theory of electronic AR ELECT AR ELECT circuits, but it also deals with a wide range of practical AR ELECT electronic applications. AR ELECT It is ideal for the hobbyist, student, technician and engineer The AR ELECT information is presented in the form of a basic electronic recipe AR ELECT book with numerous examples showing how theory can be put AR ELECTR into practice using a range of commonly available 'industry AR ELECTR AR ELECTR standard' components and devices. AR ELECTR A must for everyone involved in electronics. { { AR ELECTR 250 pages 140 x 215mm AR ELECTR Cat BP-1222 AR ELECTR A.R ELECTR A.R ELECTR A.R ELECTR A.R ELECTR• :· A.R ELECTR1 A.R ELECTR By Ian Sinclair \R ELECTR This book covers the often neglected topic of electronics power \R ELECTR supplies. All types of suppl ies that are used for electronics \R ELECTR purposes are covered in detail. starting with cells and batteries \R ELECTR< and extending by way of rectified supplies and linear stabilisers \R ELECTR to modern switch-mode systems. IC switc h- mode regulators, IR ELECTR IR ELECTR DC-DC converters and inverters. I R ELECTR The devices, their operating principles and typical circuits are all ,R ELECTR< dealt with in detail. The action of rectifiers and the reservoir ,R ELECTR< capacitation is emphasised, and the subject of stabilisation is 1R ELECTR< covered. The book includes some useful formulae for assessing 1R ELECTR< the likely hum level of a conventional rec ti fier reservoir supply. 1R ELECTRC Covers many types of supplies· batteries, simple AC supplies, ,R ELECTRC switch-mode supplies and inverters. ,R ELECTRC .R ELECTRC Includes stabilisation and regulators. .R ELECTR Explains operating princi ples and gives typical circuits. .R ELECTR For technicians, students and enthusiasts. ~ .R ELECTR 136 pages. size 135(W) x2 159H)mm .R ELECTRC IC Socket Strips Basically the same as the machine pin .R ELECTRC Cat BP-1220 variety but they have wire wrap pins. 32 way. R ELECTRC Cat. Pl-6472 R ELECTRC R ELECTRC R ELECTRC NOW O N LY .. R ELECTRC By David Mellow R ELECTRC The book describes the setting up of an 8 to 16 track studio with R ELECTRC an outline of the musical and recording gear needed, but 10+ $ 4.50 tandard 0.9mm PC pins Pk 500 pcs. · R ELECTRC concentrating on the techniques of putting that equipment R ELECTRO $2 ormally $15.95 Cat. HP-1252 together into an efficient and productive home studio. R ELECTRO NEW 20 way Cat. Pl-6473 $3.00 OW ONLY R ELECTRO It contains invalable and hard to come by advice on patchbay R ELECTRO ess than 2.5~ per pin Stock up Now wiring schemes and describes how to custom build a rack to sui t R ELECTRO your own particular requirements. 9 ELECTRO For musicians, recordi ng enthusiasts and students. =i ELECTRO Practical details on equipment. wiring, acoustics and sound '1 ELECTRO Specifications proofing. These units will not work as a PH & chl orine meter and are < ELECTRO Darlington Vceo 3CN • le l000mA 1 ELECTRO Glossary of terms and lists of useful addresses. being sold as parts only (unless you can fix them ). Parts Plot 800mW • 25°C • HFE > 2000 • 500m ~ A . '1 ELECTRO 116 pages, size 135 x 215mm. include a panel meter, a transistor rad io on/ off switch, pot/ '1 ELECTRO • Tot f 1500ns • 500mA le volume control with knob, a length of 2 core quality cable Cat. BP-1218 1 ELECTRO Cat. ZT-2216 / with a 60mm curl y cord section, a 1.5V battery holer is buil t '1 ELECTRO ONLY ea . into the case, and a 1.5V battery is suppl ied. The meter l ELECTRO alone is worth $1 0. These units were originally being sold l ELECTRO 9 1 ELECTR 1 ELECTR 1 ELECTRO 1 ELECTRO Measures AC volts from 0.3mV to 100 V and 5Hz to 1mHz. 1 ELECTRO See Catalogue for full specs. :-. l ELECTRO 1 ELECTRO I ELECTRO I HJ,_ - ~ .... ' "'" " '"' Al:. VOlT METER ,., __ ,. l ELECmo I ELECTRO I ELECTRO : I ELECTRO I ELECTRO : ELECTRO · ELECTRO ELECTRO Ca t. OT-2320 At last. Jaycar now stocks an NEW 'BOOKS FOR 1990 Everyday Electronics Data Book ( 3300 UF 63V RB ELECTROLYTIC BARGAIN ONLY $2.50 ea _ . . Catalogue price $7 .95 $2.50 $1 9.95 Electronic Power Supply Handbook Wire Wrap Machine Pin $19.95 How To Set Up A Home Re• cording Studio Normally $ 6.95 $ 4 .95 C Pin Bargain SAVE $11.95 >= ;~;;;;; ;;;;;··~;;;;~;;~ · Transistor Bargain Ph & Chlorine Meter $1 9.95 25~ 10 for $1.50 oN Lv $3.95 W as $225 NOW ~ :····:'~>12v --------DC Fan - - ~---<-: $200 Save $25 i ELECTRO ~~~g;~g ELECTRO film ,. . ~, • a==-= ~ YCAR ELF• YCAR EL.Ed Y~AH ELECTRONICS YCAR ELECTnONICS YCAR ELEClRONICS Y'CA R ELECTl10NICS ..•... , ..:"·..'~ "'~ :·-,a _ _.,,=,-:-_ .:.,:,. ' ; .. -~ "':.. e :cc 80mm square 12V DC fan. i( Quality Japanese brushless style. Limited quan tities. ii $24'.9 . 0 ;1111~~"""'""~"'i!iijil~~!i!i!!i~~!!ii!i~~~1~~~~!1!!!1!!i!~;~~~!i!!!!!i!~~~~~~ll U~ '-JAYCA ICSJAYCAR JAYCAfl I J NICSJAYCAR JAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR JAYCAR ELECTRONlCSJAYCAH FI FC:TRON ll..S. IAYrAJ".? I SJA YCAR ELECrnONICSJA YCAR ELEC 111O NICSJAYCAH ELECTRONICSJA YCAR ELECTRONICSJA YCAR [LECTllONICSJAYCAR ELECTRONICSJAYCA R ELECTRONICSJAYCA R ELEC Tl1ONI CSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJA YCAll ELECTRONIC SJAYCAll l=I r=rTRnl\11r , IAVrti.o ~ I r=rTD n "-llr'C' IA V f"/1.n r:1 Cr" Tnr H, llr"C ' IAVr- An l l.FC TRONICSJAYCAl1 ELECTflONICSJAYCAR EL[CTR O NICSJAYCAR Fl FCTllONICSJAYCAl1 r, r r , rn,...,. ~ 11 ,-. r, , • .,,,.... . ~ ... [LLCTJ1ONICSJAYCAll 111- cmm [L[Cll10N ICSJAYCAll 11 r·crnm fLECHlON ICSJAYC/\ll I LL Cll1O~ ELE:C rnON ICSJAYC/\111 11 cmm ..... ,...- ..., H-- ~ · · · - - .• . · - . - - - - --- - cs JAYCAR Ei:Eci-RoNicsJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELEcrnoNI csJAYCAR ELECTRONICSJAYCAR ELECTRo N1cs:i:.:vcAR ELECTRoNicsJAvc:.:Fi CS JAYCAR ELECTRONICSJAYCAR ELECTRONI CSJAYCAR ELECTRO NICSJAYCAR ELECTRON ICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR CS JAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRO NICSJAYCAR ELECTRONICSJAYCAR CS JAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR CS JAYC R ECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELEc i-RoN ics JAYCAR ELEC ELECTRO NICS JAYCAR ELEC ELECTRONICSJAYCAR ELEC ELECTRONICSJAYCAR ELEC ELECTRONtcsJAYCAR ELEC .R ELEC ,R ELEC ,R ELEC R.ELEC Ref: Silicon Chip August 1990 R ELEC This new Digital Sine/Square Wave Generator uses high speed CMOS and a digital filter IC to produce sine and square waves R ELEC over a very wide frequency range - from 0.1 Hz to 500kHz. R ELEC Specifications: R ELEC • Frequency Range: 0.1 Hz to 500kHz in four ranges• 0.1 Hz to 10Hz, 10Hz to 1000Hz, 1kHz to lOOkHz and lOOkHz to 500kHz. • R ELEC R ELEC Output Waveforms: Sine and Square • Harmonic Distortion: Less than 0.1 % from O1Hz to 50kHz, 0.27% at 80kHz • Square R ELEC Wave Rise Time: 10ns • Square Wave R ELEC Fail Time: 10ns • Output Level: Sine wave === =:;:TTil RELEC variable from 0-1.2Vrms; Square wave R ELEC variable from Oto 5V p-p • Output R ELEC Impedance: 600 ohm nominal • Load R ELEC Impedance 600 ohm to infinity • Protection: R ELEC R ELEC Short circuit protected (indefinite) • Display Ref: Slicon Chip August 1990 R ELEC Accuracy: (pm) 2% (ps) 1 digit R ELEC Horii! is a great project that is fun to use once you've built it. The Jaycar kit includes PCB, box, punched R ELEC Horii! can sit anywhere and when he hears a sound he will and screen front panel and all specified R ELEC back. Hori• is small and can easily be hidden. components. R ELEC Kit includes PCB, mic insert and all specified components. Cat. KC-5079 R ELEC Cat. KC-5080 R ELEC R ELEC R ELEC R ELEC R ELEC f< ELEC R ELEC R ELEC R ELEC Ref: EA May 1990 Ref: Silicon Chip April '90 R ELEC This kit features high efficiency toroid power transformer, professional high resolution 10Replace those expensive 9V batteries with an economical 1.5V D cell. Lasts much longer and R ELEC turn wire wound voltage control potentiometer, latest I.C. technology, excellent line load saves you the cost of the kit in no time. Shortform kit - PCB, potcores, battery holder, heatsink R ELEC regulation, low ripple voltage, apart from a smart plastic easel (for more information see and all electronic components supplied (excluding optional receiver parts). No box or box R ELEC specs below). hardware supplied. R ELEC The Jaycar kit is complete down to the last nut and screw as well as all hard-to-get I.C.'s. R ELEC Cat. KA-1724 CatNo. KC-5073 R ELEC R ELEC R ELEC R ELEC R ELEC R ELEC R ELEC R ELEC R ELEC R ELEC R ELEC R ELEC R ELEC R ELEC R ELEC Refer silicon Chip May 90 R ELEC Refer Silicon Chip June 90 R ELEC Designed for cars with Reluctor distributors, This add-on board prevents dangerous voltages from R ELEC this ignition kit features improved protection being delivered to a load by any dual trackng power R ELEC for the coil and main switching transistor. supply when it is turned on or off. R ELEC Kit includes PCB, die cast box and all f1 ELEC Short form kit. Includes PCB, relay and all specified components to finish the kit. R ELEC components. R ELEC KC-5076 R ELEC R ELEC R ELEC R ELEC R ELEC R ELEC R ELEC R ELEC Refer Silicon Chip May 90 Refer Sil icon Chip June 90 R ELEC This attractive 4 digit capacitance meter Ideal for a magnetic cartridge, tape player or R ELEC kit is designed for workshop, laboratory or microphones. Shortform kit, includes PCB swi R ELEC serious hobbyists. It can measure R i::LEC cable and all electronic components. capacitance from 1pf up to 9999uf in R ELEC No box front panel or panel hardware supplied. seven ranges with an accuracy of better R ELEC than+/· 1 % +/1 digit. Kit is complete Cat. KC-5077 R ELEC with all components required to R ELEC R ELEC finish construction. NE/SQUARE WAVE GENERATOR $179.50 The Cricket e $16.95 VOLTUP KIT A 1.5 to 9V DC/DC converter ± 50V (0·1 00V) 1.5A Dual Tracking Power Supply Kit · $229 ;,; ~t:lfr4'1:l~~~ff*;;/·"·•s-:srr ONLY $19.95 High Energy lgn Reluctor Distrib $17.95 $46.95 1pF · 9999uF Capacitance Meter Kit Low Noise Universal $32.95 ~ = = = = = = = = = = = = = = = = = = = = = = = , : d l ' . 1 J·RE LEC Fl ELEC MAIL ORDERS HEA D OFFICE • • 115ParramattaRoadConcord2137 Telephone(02)7472022 ------..,;,•......1.c..a,;_.._ ~ , FACSIMILE (02) 744 0767 IFORORDERSONLY TOLLFREE (008)022888 GORE HILL SYDNEY - CITY PARRAMATTA CO NCORD VISA ;~ JAYC HURSlVILLE 117 York St. (02) 267 1614 Mon-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 l02) 745 3077 Mon-Fri 8.30 - 5.30 • Sat 8.30 - 12 121 Forest Rd (02) 570 7000 Mon-Fri 9 - 5.30 Thurs 8.30 pm - Sat 9 - 4 POST & PACKING P.O Box 185 Concord 2137 HOTLINE(02)7471888 BURANDA QLD MELBOURNE-CITY SPRINGVALE VIC ADELAIDE S.A. MAIL ORDER VIA ~ $10-$24.99 1$25-$49.99 $3.75 $4.50 ROADFREIGHTANYWHERE tt~R\~~i9 :86~0 INAUSTR~~1:~upto20kg) 188 Pacific Hwy (Cnr. Bellevue Ave) (02) 439 4799• 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. 2 190 Wright Street (Cnr Selby Street) (08) 231 7355 Mon-Fri 9 - 5.30 Fri 8.30 - Sat 9 - 12 : ~t~i R ELEC R ELEC RELEC ~mi R ELEC R ELEC fl ELEC : R ELEC R [LEC R ELEC R ELEC ~ EE: II l:ECC ELEC JAYCA~ ~t~i .,,~~~"""'~""ffl~~~~~~~~~~"~"l!!li!!~!l!li!!~~~~!'!l!lllili!!~...........____________________.R~t~) :S JA'rCAT1 l:LtC I llONl~~JAYCAn l: LECTRONICSJAYCAR EL EC IHONICSJAYCAH [L[CTRONICSJAYCAfl El. ECTr10NICSJAYCAf1 El [CTRO NI CSJAYCAR ELECI llONICSJAYC • i! 111~1 1t1~rnE!I~i~i 1t1!1i~ii!Ei~1mm~ii1~~ii !tiig~iri~i~i 1t111iir1~1mi 1t1!g1i:1~~11 1t11::~r1~i~! l l li~il!~~;mi I PRODUCT SHOWCASE I ~f& i,~ M f"~!r; ~ ~lv 1 M The meter sells for $149 plus $29.95 for the temperature probe. Top of the trio is the Model 175A. This is similar in features and layout to the 135 but does not have the temperature ranges. Instead it incorporates a frequency meter with five ranges: 2kHz, 20kHz, 200kHz, 2MHz & 20MHz. Input sensitivity is 1V RMS on the 20MHz range and 35mV RMS on the other four ranges. It is priced at $189.00. For further information, contact Altronics Distributors Pty Ltd, 17 4 Roe Street, Perth, WA 6000. Phone (09} 328 2199. Mini AT motherboard has zero wait states Digital multimeters from Altronics In the market for a new digital multimeter? Have a look at this trio which all have 3 ½-digit liquid crystal displays. The model 308 is the cheapest with 17 ranges and compact size, measuring just 130 x 71 x 75mm. It is small enough to go in your pocket and at just $49.95 it is a good knockabout meter for the toolbox or in the boot of your car. A big step in measuring features is provided by the larger Model 135. As well as the usual voltage, current and resistance ranges, it measures capacitance in 5 ranges: 2nF, 20nF, 200nF, 2µF & 20µF. It also measures transistor gain and, most useful of all, temperature in 4 ranges: 200°C, 750°C, 200°F & 1400°F although you do need the optional temperature probe as well. Slimline toroids for 1-unit high cases Toroidal transformers are marvellously compact and now they are even more so with the release of these 160VA units from Harbuch Electronics. Two units are presently available, both with 2 x 35V main secondaries. One has a 12V overwind while the other has a 2 x 15V overwind, both useful for supplying low voltage circuitry such as preamps. The really good thing about these toroids is that they will fit into a 1-unit high rack case. That makes for some interesting possibilities, doesn't it? 96 SILICON CHIP Harbuch Electronics also inform us that they can now supply any of their normal range of toroids with overwind secondaries. For further information, contact Harbuch Electronics Pty Ltd, 90 George Street, Hornsby, NSW 2077. Phone (02) 476 5854. Anyone wanting to upgrade an older machine or who needs a compact AT motherboard will be interested in this new AT card which measures just 218mm square. Based on a new Texas Instruments PC AT-3 chip set, the board will operate at 8MHz or 12MHz with O or 1 wait state. Switching can be done from the keyboard or via jumpers on the motherboard. Even though the motherboard is half size, it has five 16-bit slots and one 8-bit slot. 1 megabyte of 80ns RAM is standard and the ROM is two 64K by 8-bit organised as 16K by 16 bit. For further information and pricing, contact Electronic Solutions, PO Box 426, Gladesville, NSW 2111. Phone (02) 906 6666. Tandy portable has 20Mb hard disc The Tandy 1400 HD is a full function IBM PC compatible laptop machine with a 20 megabyte hard drive and a 720K 3.5 inch floppy drive. The inbuilt readout is an 80 x 25 character supertwist liquid crystal display with backlighting. As well, you can connect an external colour monitor and any RS-232 peripheral. Also supplied with the 1400 HD is MS-DOS, GW Basic, a real time clock and a parallel port adaptor. The compact keyboard has 76 keys including 12 function keys. It will also support an external 101-key enhanced keyboard and an 8087-7 maths coprocessor. The unit weighs 6.5kg and retails for $3499. It is available from all Tandy Computer stores. Dry as a bone? Get a humidifier Air conditioning is wonderful but in the winter the air can get so dry that you run the risk of being dessicated by the end of the day. To avoid this problem and also irritation of the nasal passages, why not consider a humidifier? For athsma sufferers, it could be a boon. This ultrasonic unit vapourises the water in its tank by means of an ultrasonic transducer, so it puts out a cool mist. Power consumption is quite low, 55 watts. The unit works very well and you can adjust the controls for high or low mist output. Our only complaint is that you have to take the tank off and turn it upside down to fill it. The infltructions are none too clear on this point so it would be quite easy for an uninformed user to try to fill it by just removing the top vent. The net result of that is that 4 megabyte floppies . in 3.5 inch format 3M Australia has upped the stakes in data storage with the release of the world's first 4 megabyte 3.5 inch floppy diskette. These new Extra High Density (ED) diskettes are based on barium ferrite which 3M sees as eventually leading to development. of floppies of up to 100 megabyte capacity. · Drives for the new 4 megabyte floppies are expected to be released on the Australian market before the end of this year. For further information on the new 4 megabyte floppy or any of 3M's magnetic media range, users can call the toll free technical hotline on Monday to Friday between 8.30am and 5.00pm on (008) 022 293. water goes everywhere. Once you are over that hurdle though, the unit is very worthwhile for anyone who has a problem with low humidity. The unit is available from all Jaycar stores at $109.50. Car on the nose? Try an ioniser If air ionisers work for you then you might like to try this unit which plugs into the cigarette lighter socket in your car. It is priced at $49.95 and is available from Rod Ir- ving Electronics, 74 Parramatta Road, Stanmore, NSW 2048. Phone (02) 519 3134. AUGUST 1990 97 M,,._ I• •I BNC MALE PLUG --r 1 CE NT RONI CS CONNECTORS • 14 Way plug .. P12205 • 24 Way plug .... P12207 • 36 Way plug .... P12210 10. 100+ 1-9 $2.95 $2.50 S2.00 SOLDER CENTRONICS IN-LI NE SOCKET • 36 Way P12211 1-9 10+ $4.50 $4.95 I I IDC SOC KETS 1·· SPAC ING ~ 12.t • 10 Pin $1.95 P12100 $1.75 • 16 Pin $1.50 $1 .75 Pl 210l • 20 Pin $1.75 $ 1.95 P12102 • 26 Pin $1.75 $1.95 P12103 OMNI-DIRECTIONAL WIRELESS MICROPHONE Cat. A 10450 BNC PANE L SOCKET $24.95 iiiii These superb rack mount cabinets will g iv e your pro1ec1s a re al pro fessional appearance 1 Jus1 look at these features • All dimensions conform 10 the ln1ernat1onal Standard • Al! aluminium constructton • Cho ice of blac k or natu ral 11nish • Deluxe bru sh fi nish anoci1 sed fro nt panel • Remove able !Op and bo1tom lid • Venlllated hd Ho rizontal Depth : 254m m A E xternal Front Panel Height m m B Mounting Ho le Cantr es mm C Interna l Chassis Height mm A B C Finish Cat.No. Price 44 34 38NaturalH1040 1 S59.50 88 57 82 Natural H\ 0402 S69 .50 , 32 89 126 Natural H 10403 S79.50 44 34 38 Black H 104 11 S65.00 88 57 a2 a1ack H 104 12 575.00 132 89 126 Black H 10413 $85.00 1-9 $2.00 $3.00 $2.50 $3.50 $3.25 if- These terminal• feature intertoc:king ends to form any number of connections. 1-9 10+ Standard 5mm apac:ing pins. 100+ • DE9P 9 pin plug P\2166 $2.95 $2.50 $2.00 • DA15P 15plnplug P\2168 $3.50 $3.00 $2.50 • DB25P 25 pin plug P\2170_ $3,95 · $3.50 $2.95 • P10520 1-9 $0.75 10+ 2way 100+ $0.70 $0.60 • Pl0521 $1.00 $0.90 3way ~ BNC SOLDER LESS TWIST ON PLUG 1-9 D TYPE IDC SOCKETS 9 pin socket 1-9 10+ 100+ $2.95 $2.50 $2.00 P12167 • CA 15S 15 pn socket P12169 $3.50 $3,00 $2.50 . 0B25S 25 pin aocket P1°2171 $3.95 $3.50 $2.95 PASS IV E IN FA- R ED DETE CT O RS Thea.e du11element ptiHive lnll..fed detec1ora very reli• ble w1y 10 en•ure security ■nd prot ■ ction when u.ed in conjunction with 1n alarm 1 =~~~:;/!ti~~~~:~~~~~e:y ~n intnJder. They ■re In I compact beige col cabinet fot either owed duign~ ?12200 10.. 1-9 $3.95 100+ $3:00 $ 2.95 • Socket P12201 10+ 100+ CANNON TYPE 3 PIN LINE FEMALE 1-9 10+ 100+ P10ll64 $4.50 $4.20 $3.20 CANNON TYPE 3 PIN CHASSIS FEMALE 10+ 100+ P10ll66 s5_g5 '5.50 1-9 s4.oo RECH AR GE AB LE12 V GELL BATTERIES TEXTOOL IC SOCKETS (ZERO INSERTION FORCE) TIie• ZI F •ockel9 are perlact for ln•rtlng and 111movlng EPROMS •o H not to damage the IC plna. 1-9 10+ • 16 pin P17016 $16.95 $13.95 0 [i] /~ :--- Ca1s1502912V12AH $29.50 Ca1S1503112V26Aci $39.50 CatS1503312V45AH $49.50 MINIATURE HEATSI NK 1 A Qrf'n! lintf' !elfo .,., 11 you are ">ho r \l ' t' G rE"d1 pr1C (' too 0€ Cd< , ',P ,.,., .,, mpori airPr t so yo l, '><ive' '>1-) il ( '.)1 rT1t> ll -. ulf1-. 1 Q1{ , , 1 ) ! W I , q , 11 im rn • • • •l h (l b 10 S0.40 $0.35 P17028 $26.95 $24.95 VOLTAGE REG UL ATORS BARG AINS 40 pin ,. P1 7040 $34.95 $32.95 ~ :-~~ ~ 10dB IN-LINE CO AXIAL A.MPLI FIER Reduces toss from sp11ne1s and long c able run s Sui table fo r use w1! h antennas coax ial !eed lines and VC R s A C adapto r mc luded SPECIFICATIONS : Descr 1pl1on 7805UC 7812UC 7815UC 7905UC 7912UC 7915UC 78L05 781..12 LM324 555 741 1·9 Ca t L, 504 3 $39. 95 !C $0.50 $0.45 $0. 50 $0.45 so.so $0.4 5 $0.60 $0.55 $0.60 $0. 55 $0.60 $0.55 $0.45 $0. 40 $0.45 $0.40 $1.00 $0.90 $0.40 $0.38 so.so $0.45 ~r~~~~i Range . ~-900~H 1 Power Requirements : 1'2 V A C Ad ap1o r (1ncluded 1 Input Impedance : 75 o hm Output Impedance : 75 o hm Cat . No Description Price P l 1000 100 Ho les $ 2.75 P1 1005 640 Holes $10.75 P11001 640 · 100 Ho les $14.95 P11Q09 64 0 200 Holes $17.50 P1 10 10 1280• 100 rl oles $26.95 p11 011 1280-300Holes $32.50 P l1012 1280 · 400 Holes $ 39.95 P 110 15 1920 · 500Holes $59.95 P110 19 2560 • 700 Ho les $69.95 □ C at X 1565 1 Male to Female CE NTRONICS GENDER CHANGERS (EX SCOTCHCALJ All pri ces per box and include tax 80()7 REVERSAL FILM 250 x 300mm ( 10 sneets 1 300 x 600mm ! 5 sheets ) • Save s modtfy1ng or repla c ing non -mating AS 2 32 cable s • All 25 pins wired straight lhrougn C al X 15650 Male to Male • ~ emale 10 Fema le • Saves mod 1ty1ng 01 :eplacmg 11on-ma11ng Centromcs c ables • All 36 pins wi,ed ~tr a,ght 1hrougn 3M DYN AMAR K PHOTOSENSITIVE Cal X 15663 Male to Ma le c -,1 x 15€6 , Male to Female S39 .95 $54 .95 8009 BLUE ALUMINIUM 250 • 300m m ! 10 shee1s1 300 x 600mm !5 snee1s• $69 .95 S79 .95 8011 RED/WHITE ?50 x 300m m { 10 sheets I 300 • 600mm (5 sheets I $64.95 S74 .9S 8013 BLAC K/Y ELLOW 250 x 300mm ( 1O sneets l 300 • 600mm 15 sheets I S64 .95 S74 .95 8015 BLAC K/WHITE 250 x 300mm t 10 shee1s 1 300 x 600m m ( 5 sheets) $64 .95 $74 .95 8016 BLUE/WHITE 250 x 300mm ( 1O shee1s 1 300 • 600mm {5 sheei s ) S64 .95 S74 .95 8018 GREEN/WHITE 2 50 x 300mm ( 10 snet-:s 1 300 x 600mm (5 sneetsJ $64 .95 $74.95 4 TI/ INTE RFE RENCE FILTER ' Era se your EPAOM s qucck ly and sal ely Th,s un,1,s the cost eHect ,v solution to your probl em s II will e ra se up 10 9 • 24 p,n devices 1n complete satety in about 40 m inute (less !or less ch,p s) Fc alurcs 1nclud o • Cn,p d1;iwor h ;is conduchvc loa pnd • M.- w, s powor1•(1 •:,:i~r~: ~~~~~s~,~n;~~~~;~fy erased • Eng1nee1ed to preve nt UV e - posu re • 01111on~•ons 21 7 • BO • 6fl m m { ,, 1 X 149~0 TE LECOMMUNICATION CURL CORD •U S plug to U.S plug • Re pl acement hand set cord • Lengtn 4 5 me1res Cat. Y16023 . $7 .95 SPECTR P17024 $19.95 $18.50 ' Cun,ntd,ow , 20mA ~=~ti~~v~~~g:~~d_r;!ii;,t· l.akproof and in 3 c:omvenienl sizes, these long ser.-ice He batteri• are ideal fot burgular 9Vst&m11 . emergency ighling or a, a compu ter backup power ~pply id,,.1! for many power needs C ,t• Nt • 24 pin BREADBOARDS 8005 BLACK ALUMI NIU M 2 50 x 300 mm 110shee!s1 $69 .95 300 x 600mm !5 sheel s J $79.95 10-99 100• MINI MOMEN TARY PUSH BUTTONS • 28 pin $69.95 • Plug (dJ:-- - z P10531 $2.50 $2.25 S2.00 ~~:r::i~;::::~:~~\ampar Prot:ecta normlll 1lzed roon.. • Covar• an 1re1 12m x 12m IDC CENTRONICS 36 WAY PLUG & SOCKET 10+ 100+ P10ll62 $3.115 $3.50 $2.90 1-9 10-99 100. P10530 $2.115 $2.75 $ 2.00 0 $0.80 •re• • DE9S CANNON TYPE 3 PIN CHASSIS MALE 1-9 BNC CRIMP PLUG PC B MOUNTING SCREW TERMINALS (INTERLOCKING ENDS) D TYPE IDC PLUGS 10+ 100+ • pu•h off S11070 S0.70 S0.60 $0 .50 • 40 Pin P1 2 108 1-9 1-9 10+ 100 + • pu•h on S11060 S0.60 S0.50 $0.40 $1 .80 • 36 Pin P1 2106 10-99 100. P10516 $2.50 $2. 25 $1 .50 • 34 Pin P12104 CANNON TYPE 3 PIN LINE MALE P10ll60 $4.75 $3.90 $3.00 4m Tuneable : 92 - 104MHz Freq. Response : 50 15kH1 R ange: Over 300 tee! 1n open field Modulation : Fli.-1 Power Source : 9V Banery Type : Etectre! Condenser Dimensions : 185 x 27 ._ 38mm Weight: 160 grams MASTER RACK MOUNTING CABIN ETS ii 1-9 10-99 100. P10514 $2.50 $2.25 $1.50 t~u 2 L I SPECTRO L 64 Y MULTI TUR N TRIM POTS Ca1 No Oescnp110n 1 9 A14700 10A $3 50 Al4 7 10 20R SJ 50 R14 720 SOR SJ 50 R 1 ◄ 7 J0 100A SJ 50 A 1 ◄ 740 200R $3 50 A14 750 S0OA SJ .50 R \ 4760 1K SJ 50 Al4 770 2K $3 50 A 14 780 SK $3 .S0 A14 790 l0K $350 A 14800 20K SJ 50 Rl48 l 0 50K $3 50 A 14820 IOOK $3 50 f1148J 0 ?OOK SJ 50 A 148-40 SOOK $3 50 Al-4850 1M $3. 50 - 10 1 $3 .20 SJ .20 $3 .20 SJ .20 $3 20 $320 SJ .20 SJ20 $3 .20 $320 $ 3 20 S320 S3 20 $3 20 $3 20 SJ .20 INSUL ATION DISPLACE MENT TY PE HEA DER PL UGS ~. 11n pl<1ted nbbon cable plug thal plugs 111~ •iv mtt' PC B rnoun11nq IC -.ockets Air ,n, lude p1e s-.-h1 c ap Iha ! !11~ into •1,,11,1,P f, ,i lf n t p luq 0vt' t IDC C.-lt)lt-> Cat.No . Oescnpt 1on 1-9 p · , . " J 1J Jlll l St .SO p, · · S1 .60 S2.95 S5.95 10 S1.40 S1 .50 S2.75 S5.75 PO. Box 620. CLAYTON 3168 Order Hotline: 008 33 5757 (Toll free, strictly orders only) POSTAGE RATES $1- $9.99 $10- $24.99 $25- $49.99 $50- $99.99 $100- $199 $200- $500 $ 500 PLUS $3.00 $3.50 $4.50 $6.00 $6,00 FR EE FREE The aoove postage rates are lor basic postag e o nly . Road Freight. ~~:~i:~~ 1t~~~:~~~~a~:SIII be All sales t ax ••empt orders and 1 R/~~6:.i~~~H~~t~°ALE 56 Renver Rd. Clayton Ph . (03) S43 2166 (3 li nes ) ::a ~~0 LEADS PRINTERS & ACCESSORIES ' PR INTER STAN D " AUSTRALIAN MADE" • Restores order to your work area • Conveniently stacks paper printout in document tray automatically • Made of plastic coated steel • Suitable for most printers • Excellent value at this price • 80 COLUMN KEYBOARD EXTENSION LEAD 5 Pin Din plug and socket P19038 ...... ...... ........ $6.95 COMPUTER EXTENSION POWER LEAD P10254 ............. .....$11.95 C21054 .................. $24.95 KEYBOARD ACCESSORIES DUST COVER Keep your computer and accessories tree of dust and grime w hlle not in use XT* Cover Set C21066 ........ .. ........ $14.95 AT* Cover Set C21068 ..................$16.95 HS-3000 HANDY SCANNER INCLUDES [J ~ Slide your keyboard neatly away when not in use. Gives you more desk space. Securely holds any keyboard , wide or narrow. C21083 ...... .... ... ..... $64.95 half-tone pattema. •·.Bu i lt ◄ n scanner view w indow for ·,ccurate scanner placement ,, Yellow.green LED acan light • Visible LED light to monitor scanni ng apeed • Bundled with ZSoh'1 PC Paintbruah Plu., OFh Scan Utility and Image Toala C22045 ...... ........ .-.... ..$695 MONITOR EXTENSION LEAD • 9 Pin D socket to 9 Pin D plug ENCLOSED PRINTER STAND DELUXE PRINTER STAND • Restores order to your work area w tthoul occupying extra space • Feeds and refolds paper under the pnnter automatically • Ad1ust able paper deflec tors to ensure smooth flow of paper • Made of moulded plas11c • Suita ble !or most pnnters • 47 CPS letter quality Pica • 24 Pin letter quality • 142 CPS Draft Pica KEYBOARD STORAGE DRAWER C22046 ..... ......... .. ..... $995 C21055 .............. ....$49.95 COMPUTER PAPER Quality paper at a low price! • 60 gsm bond paper • 11 x 91 /2" 2000 Sheets C21001 .. .....................$41 RIBBONS Stores keyboard under the PC or monitor conveniently out of the way. Fits PC/AT keyboard or 2 3/4 .• (H) X 22 1l4"(W) x 9 1/2"(D) •YU•E21B • Transparent cover makes it easy to chec k on paper supply .• Paper can be fed from the centre or the rear according to the design of the printer • RemovablP. drawer which allows paper to be changed without moving the printer • Retractable rear basket makes print•out collection fast and convenient • Suitable for most printers • 15 x 11" 2500 Sheets C21012 ........... ............$69 P.C ACCESSORIES NEW MODEMS MAGIC STAGE THE XITEL XM •12E MOD EM A worki ng bench for your Mouse. •High quality ABS plastic and anti•static rubberised top •Stationary holder •Includes pull•out shelf for Mouse •Dimensions : 280 x 260 x 25mm • Fits over keyboard Tile XM- 12E ia deai gned for appl ications that require high speed, full duplex da ta communications auch H d ata be&e aeceM, file tr ansfer and el~tronlc mail (e,11. Auatpac 111d Keylink ) H well H d ireet communi cations and othef' CCITT .-'Id Bell syste ma. KEY FEATURES: • 1200 bpe Asynchronoue (CCITT V.22 B(ll) or Bell 212A) • 300 bps Asynchronous (CCI TT V.21 or Bell 103) • Full Duplex data communlcatio n,s on a suindard Telecom PSTN 2 wire circuit • Auto-Di al , Auto-An11wer and AU1o-Disconne ct (CC ITT V.'25 or Bell) • Automatic data rate aelecUo n ln both Originate and Auto.AnaW9r modes • Compatible with the Industry Standa rd Hayes AP Command S.l • To ne or Pulae Di all ing with CaJt ProgreH Moni toring and Internal Speaker .......................................... $249 BBM 1234 E • Auto V21 , V22, V23., V22bis • Bell 103 12 12A • Asyne/Syndvonoue Ex\ernal ········ ····· ·········· ······· ··· ··· ····· ·$499 C21080 ....... .......... $24.95 PRINTER RIBBONS TO SUIT: • CP80, SX80, DP80, BX100, BX100, MB100 1·9 10+ C22036 .. $19.95 $17.95 RIPPER STRIPPER Remove ugly paper feed edges quickly and cleanly with this simple little gadget C21085 .................. $14.95 • MX80, FXB0, RX80, FXB00, MX70, MX80, LX800 1·9 10+ • MX100, FX100, RX100,LQ1000 1·9 10+ 1·9 C22003 .. $12.95 • C ITOH 8510·1550 1.9 C21087 ... ... ........... $14.95 C22051 .. $13.95 10+ $11.95 10+ $12.50 NATIONAL PANASONIC KXM110 PRINTER RIBBON C22034 ................. .$19.95 2 ~ r~ '" .... .. ~ :r :1:e ·-I MOUSE MAT • A quahty mouse mat tor accurate and comfortable tracking • Ant1-stahc • 265 x 225mm ... $9.95 ROD IRVING ELECTRONICS MELBOURNE: 48 A'Beckett St, Phone: (03) 663 6151 NORTHCOTE : 425 HighSt,Melb. Phone : (03) 489 8866 SYDNEY 74 Parramatta Rd , Stanmore .. NSW. Phone: (02) 519 3134 • LX80 Use it to clean : • Computer keyboards • Printers • Video recorders • Computer circuit boards •1.8 metres P19029 .................. $14.95 • 3 metres P19030 .................. $19.95 • 10 metres P19034 ....... ........... $39.95 ROD IRVING ELECTRONICS C22031 .... $16.95 $15.25 C22002 .... $19.95 $17.95 MINI VACUUM CLEANER PRINTER LEAD • Suits IBM' PC/XT, compatibles • 25 pin "D" plug (computer end) to Centronics 36 pin plug ~ -· langu1ge auppott .... ..... ................................. $389 P19032 ....................$9.95 C21075 C21081 .................. $84.75 • Oata bHe and hlgh"'8vel • Support for over 1SO printeralpfottere • Support for ov• 22S diaplay adeptore ~ ~ • 120 C.P.S, Near letter quality • Colours· Red, Violet, Blue, Green , Yellow, Oranoe, Black C21058 80 column $79.95 STAR 2410 PRINTER • WIDE 4. 13" (105mm) actn width • Thirty-two ahadea of grey 021056 .................. $34.95 KEYBOARD SLIDEAWAY FREE SOFTWARE ! ii'>" PC PA INT BRUSH . ,A & IMAGE TOOL .==--✓- · ~ · 100/200/300/400 awitdiab&e DPI re.olutio n • Four encoding modN : B/W and three • 132COLUMN C COPY HOLDER (YU-H32) • Adjustable arms allows easy positioning • Copy area 91/2" x 11 " • Sliding line guide • Clamp mounting C21062 ..... ............. $39.95 CLAYTON MAIL ORDER 56 Renver Rd , Phone: (03) 543 7877 Fa x: (03) 543 2648 E RRORS & OMMI SI0NS E XCEPTED IBM' . PC· . XT' . AT' . are regi stered trademarks ol mtern at1onal BuSlness Mach nes. Apple' 1s a registered tradl!mark of Apple corpoat1on All sales I•• e•empl o r ders a n d wholesale mqumes 10 ::a 0 2 n -~=== "' AITAONICS WHOLESALE . 56 Renver Rd , Clay1on Ph (03) S43 2166 (3 hnes) want good quality sound without having obtrusive speaker boxes. They are avaiable from all Arista outlets. Drivesafe alcohol breath analyser Flush-mount loudspeakers for unobtrusive hifi ed terminals for speaker connection. The nominal impedance is 80 and the sensitivity is relatively high at 90dB/1 watt/1 metre. The speakers are designed to go into any stud wall and they can be mounted directly onto Gyprock with the aid of the steel mounting frame. They are mounted from the front of the wall and the grille is removeable to allow this. Of course, you could install them into brick cavity walls too but there is somewhat more work in cuting the hole! Priced at $199.95 a pair, they offer a good solution to those who For many homes, these flush mount loudspeakers from Arista represent an idea whose time has come. After all, there are many situations where the usual black boxes are just not appropriate. These well made units come with a 120mm long throw woofer and 20mm mylar dome tweeter. The woofer has a polypropylene cone and a closed cell foam surround. The baffle has a 1st order LC crossover network (operating at 3kHz) and is fitted with spring load- CD ' ). m ·• · m Price drop for Interlink modem Interlink Electronics has announced a price drop for their IQ 12345 5-speed modem, to $995 plus sales tax. The unit has a maximum data transfer rate of 19,200 bps (bits per second) and uses standard AT commands. It also has data correction, corn100 SILICON CI-!IP · . I ~ ~ .· pression and DES data encryption for extra security. It can also handle 2400 to 9600 bps full duplex synchronous and asynchronous modes, as well as 1200/75 and 75/1200 Viatel, and supports both CCITT and Bell standards. For more information contact Interlink Electronics, 113 Fitzroy St, St Kilda, Vic. 3182. Feeling tipsy, mate? If you have been drinking and think that you may be over the limit, this unit can eliminate the doubt. Just switch it on, blow into it and the reading is there on the meter. While the unit is not intended to give any sort of legal evidence it could be handy for those who frequently find themselves in a social drinking situation. It could also be good for party hosts guests could test themselves and then elect to go home by taxi. The Drivesafe breath analyser retails for $99, a low price to pay when you consider the risks involved of driving with an alcohol blood content which is over the legal limit. For further information, contact Access Communications, 33-35 Alleyne Street, Chatswood, NSW 2067. Phone (02) 417 7474. 4 channel transient waveform analyser Recently released from Rapid Systems is the R1250 transient waveform analyser which in- tegrates a 12MHz AT computer with 4 independent 1MHz 12-bit analog to digital converter channels. These allow multichannel recording in applications such as biomedical instrumentation, transducer output analysis, transfer function measurements and data acquisition systems. Some of the product highlights are as follows: window driven EGA/CGA/Hercules/VGA software; programmable gain from 2mV/div to 32mV/div; vertical and horizontal waveform zooming; programmable sample rates from 1Hz to 1MHz; autosave waveforms to built-in 40 megabyte hard drive; print/ save/retrieve/change colour of waveforms; and differential or single ended inputs with digital or analog triggering. For further information, contact Warburton Franki, PO Box 14, Lidcombe, NSW 2141. New test & measurement distributor in NSW A new test equipment distributor specialising in Fluke digitial multimeters has been established in NSW. Founded by Tim Wortman, the company will also provide a service to companies and individuals needing fast access to other test equipment products such as oscilloscopes, frequency generators and power supplies. Tim Wortman will be well known to many in the industry from the time when he established the Marconi Instruments operation in Australia and more recently as 12MHz XT motherboard from PC Marketplace How cheap can motherboards get. This one features an NEC V20 processor and clock speeds of 4.77Mz and 12MHz which are hardware (keyboard) or software selectable. There are 8 expansion sockets and a socket for an 8087 maths co-processor. The motherboard only, with all chips except RAM, is $125. With 640K of RAM installed it goes for $250. Or you can go all the way and install 1 megabyte of RAM for $300 all up. With this option you get a utilities disc which lets you use the extra 384K of memory as a RAM disc or printer buffer. For further information, contact PC Marketplace, PO Box 1100, Lane Cove, NSW 2066. Philips-Fluke Australasian business manager. For knowledgeable service on Fluke and other T & M products, contact Tim at Tech-Fast T & M Pty Ltd, 14B Maxwell Street, Turramurra, NSW 2074. Phone (02) 988 3865. 9-pin dot matrix printer from Facit The new Facit Bl 200 9-pin dot matrix printer is claimed to offer all the basic printout options in a compact and easy to use package. Paper loading is automatic and it is possible to print cut sheets without having to remove a loaded continuous form. A "quiet" key on the control panel reduces print noise when necessary. It is possible to select draft or NLQ (near letter quality) modes, font and pitch both from the front panel or the driving computer. The B1200 supports both IBM Proprinter and Epson FX printer command sets. A parallel interface is standard while a serial interface is AUGUST1990 101 For further information on the ECAT, contact the Australian distributors, DGE Systems Pty Ltd, PO Box 111, Broadmeadow, NSW 2292. Phone (049) 69 1625. Sanyo MBC 38SX has 386SX processor Batteries for cordless & mobile telephones Perhaps the biggest problem that users experience with mobile and cordless phones today lies with the battery going flat at the wrong time. With this in mind, Premier Batteries has released a new range of sealed rechargeable batteries to suit most cordless and mobile phones now available. For some models, high capacity batteries are available which give up to 40% more standby time before recharging is needed. These can be charged using existing equipment. For further information, contact Premier Batteries Pty Ltd, 7/27 Childs Road, Chipping Norton, NSW 2170. Phone (02) 726 7701. optional. And unlike most printers, the B1200 has a colourful presentation which is a change from that featured on competitive models. For further information, contact Elmeasco Instruments Pty Ltd, PO Box 30, Concord, NSW 213 7. Phone (02) 736 2888. AT processor board on Eurocard A new processor board for control and instrumentation projects is now available using an 80286 and AT compatible output ports. MSDOS applications and the MS-DIS system will run unmodified and can be loaded into the onboard ROM. Known as the ECAT, it runs from a single + 5V supply. Using the Eurocard format, the board has serial and parallel ports, 102 SILICON CHIP This 32-bit PC, the Sanyo MBC-38SX, uses a 386SX chip set which is a hybrid 16/32 bit design. Internally, it works like a 32-bit 386, with all its capabilities such as multi-tasking and virtual memory. To the outside world though, the 386SX is a 16-bit machine. This makes for a big saving in cost. The MBC-38SX comes with 1 megabyte of RAM as standard and can have up to 2 megabyte of RAM on board. Also standard are an IDE drive connector, parallel printer port and five expansion slots. For further information, contact Sanyo Office Machines Pty Ltd, 5-9 Harbourview Crescent, Milsons Point, NSW 2061. Phone (02) 498 2799. Cordless soldering gun with temperature control a calendar-clock and supports a keyboard and 3.5-inch and 5.25 inch floppies. Its timers, interrupt controllers and DMA circuits are claimed to work exactly as they do in an IBM PS/2 model 30. · A 60 watt cordless soldering iron with manual temperature control and automatic switch off is now available from Scope. Powered by two nickel cadmium cells, it is capable of doing between 40 and 140 solder joints between recharges. Three different charger options are available. For further information, contact Scope Laboratories, PO Box 63, Niddrie, Vic. 3042. Phone (03) 338 1566. Magnetic finger & tweezer set j New 6Mb card uses 1MB RAM chips This new card accomodates up to 6 megabytes of RAM for expanded or extended memory for IBM PC/XT/AT machines. It has an 8/16 bit bus so it can give high speed for 16-bit machines and still offer compatibility with XT. machines. The card is one of the first to offer memory expansion using either 256K or 1Mb DRAM chips. Further expansion is possible with additional cards making up to 42Mb EMS memory possible. Compatible chips are 2 x 41425 and 1 x 41256 (256K banks) or 9 x 411000 (1Mb banks). Software utilities supplied include drivers for EMS, RAM discs and print spooling. For further information, contact Electronic Solutions, PO Box 426, Gladesville, NSW 2111. l '\ \ Having trouble picking up those nuts and screws that slide under everything when you're trying to put them on? If that's the case, this magnetic tool set from Arista will come in handy. The tool contains a magnetic finger and two insulated tweezers, for getting those tiny nuts out of awkward places. They're suitable for most equipment repair jobs and are available from Arista Electronics outlets for $11.95. Pin diode attenuators Now available from Merrimac are two electronic pin diode attenuators which cover the frequency range from DC to 200Mz. Nominal impedance is 500 and insertion loss is a maximum of 2dB with a control voltage of 15V. The attenuation range is from O to 20dB minimum over the range from 2MHz to 200MHz. For further information, contact George Brown Group, Marketing Division, 456 Spencer Street, West Melbourne, Vic 3003. Thermostat cutouts with 10 amp rating These thermostat cutouts could be used as a temperature controller or to provide overheating protection for heating appliances or electronic equipment. They are rated to switch 10 amps and are claimed to be good for 6000 cycles at 250V. Their nominal temperature cutout point is 80°C. The cutouts are available from Altronics Distributors of Perth for $3.50 each. Phone (09) 328 2199 for more information. Is Your Product Getting The Exposure It Deserves? Consumers need to see your product if you want them to buy it Contact Paul To Reserve This Space - (02) 979 5644 AUGUST 1990 103 Silicon Chip BACK COPIES February 1988: 200 Watt Stereo Power Amplifi er ; Deluxe Car Burglar Alarm ; End Of File Indicator For Modems; Low Ohms Adaptor For Multimeters ; Line Isolation Unit For Phone Patch; Easy Tips On Headphone Repair. March 1988: Remote Switch For Car Alarms ; Telephone Line Grabber; Endless Loop Tape Player; Build Your Own Light Box; New Life For RadioCassette Players; Old-Time Crystal Radio. April 1988: Walkaround Throttle For Model Railroads , Pt. 1 ; pH Meter For Swimming Pools ; Slave Flash Tri gger ; Headphone Amplifier For CD Players; What Is Negative Feedback , Pt . 1 ; Mobile Antennas For The VHF & UHF Bands . May 1988: Optical Tachometer For Aeromodellers; High Energy Ignition For Cars; Ultrasonic Car Burglar Alarm; Walkaround Throttle For Model Railroads , Pt.2; Designing & Building RF Attenuators ; Motorola MC3334P High Energy Ignition IC Data. June 1988: Stereo Control Preamplifier (Uses LM 833), Pt.1 ; Breakerl ess Ignition For Cars Using Hall Effect Pickups ; Mega-Fast Nicad Battery Charger; Automatic Light Controller (Uses PIR Detector); RF Sniffer Probe & Preamplifier; What Is Negative Feedback, Pt.2 . July 1988: Stereo Control Preamplifier , Pt.2 ; Fitting A Fuel Cut-Off Solenoid ; Booster For TV & FM Signals ; The Discolight Light Show , Pt.1 ; Ton e Burst Source For Amplifier Headroom Testing; National Semiconductor LM833 Op Amp Data; What Is Negati ve Feedback, Pt.3. August 1988: Building A Plasma Display; Universal Power Supply Board; Remote Chime/Doorbell ; High Performance AC Millivoltmeter , Pt .1; Discolight Light Show , Pt.2 ; Getting The Most Out Of Nicad Batteries; Data On Insulated Tab Triacs . September 1988: Hands-Free Speakerphone; Electronic Fish Bite Detector; High Performance AC Millivoltmeter, Pt.2; Vad er Voice ; Motorola MC3401 8 Speakerphone IC Data; National Semiconductor LM 1 2 1 50W Op Amp Data & Applications; What Is Negative Feedback, Pt.4 . October 1988: Stereo FM Transmitter (Uses Rohm BA 1 404); High Performance FM Antenna; Matchbox Crystal Set; Electronic House Number; Converting A CB Radio To The 28MHz Band ; Electronics & Brock's BMW Blaster; Oueensland's Powerful Electric Locomotives. November 1988: 120W PA Amplifier Module (Uses Mosfets); Poor Man's Plasma Display; Automotive Night Safety Light; Adding A Headset To The Speakerphone; How To Quieten The Fan In Your Computer ; Screws & Screwdrivers, What You Need To Know ; Diesel Electric Locomotives. December 1988: 120W PA Amplifier (With Balanced Inputs), Pt. 1 ; Diesel Sound Generator ; Car Antenna/ Demister Adaptor; SSB Adaptor For Shortwave Receivers ; Electronics & Holden 's New V6 Engine; Why Diesel Use this handy form to order your back copies ~ I --------------- ------------------- I Please send me a back issue for: I ! l May 1988 I ~ I I L March 1989 I I l- □ □ , June 1988 October 1 988 August 1 989 January 1 990 June 1 990 Nov. ember 1 988 n r1 □ March 1 988 □ April 1 988 July 1988 □ August 1988 0 January 1 989 □ September 1988 □ February 1 989 □ June 1989 □ July 1989 □ December 1 989 I"! December 1 988 Apri l 1989 i7 May 1989 r1 September 1989 □ October 1989 I.] February 1 990 □ March 1990 July 1990 □ □ □ April 1990 November 1989 Enclosed is my cheque / money order for $ _ _ _ _ _ _ or please debit my Card No .IL .....1,_......L_......L__JI '-I_L__._...,L.._] I'-.....1,_.....,l_.....,L__JI l-....J__,C........,__, Signature _ _ _ __ _ __ _ _ _ _ _ Card expiry date _ __,__ _ Name _ _ _ _ _ _ _ __ _ __ _ _ _ __ __ _ _ _ _ __ (P LE ASE PRINT) I I ' Street. _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __ Suburb/ town · ____ Postcode._ _ _ _ - ~--------- ---------- 104 S ILI CON CH IP •--7 February 1 988 D □ □ May 1990 Bankcard MasterCard D Visa Card Price: $A5.00 each (includes postage). Overseas orders add $A 1 . 00 per issue for postage . NZ & PNG orders are sent by air mail . Detach and mail to: SILICON CHIP PUBLICATIONS PO BOX 139 COLLAROY BEACH NSW 2097 OR FAX: (02) 979 6503 l I _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _J _ Electrics Killed Off Steam; Index to Volume 1. January 1989: Line Filter For Computers; Ultrasonic Proximity Detector For Cars; Simple Computer Sound Repeater; 120W PA Amplifier (With Balanced Inputs) Pt.1; How To Service Car Cassette Players; Massive Diesel Electrics In The USA. February 1989: Transistor Beta Tester· Minstrel 2-30 Loudspeaker System; LED Flasher For Model Railways (uses LM3909) ; Build A Simple VHF FM Monitor (uses MC3362). Pt. 1 ; Lightning & Electronic Appliances ; Using Comparators to Detect & Measure. March 1989: LED Message Board, Pt.1 ; 32-Band Graphic Equaliser, Pt.1 ; Stereo Compressor For CD Players ; Map Reader For Trip Calculations ; Amateur VHF FM Monitor, Pt.2; Signetics NE572 Compandor IC Data; Electronics For Everyone - Resistors. April 1989: Auxiliary Brake Light Flasher; Electronics For Everyone: What You Need to Know About Capacitors ; Telephone Bell Monitor/ Transmitter; 32-Band Graphic Equaliser , Pt.2 ; LED Message Board, Pt.2 . May 1989: Electronic Pools/Lotto Selector ; Synthesised Tom-Tom ; Biofeedback Monitor For Your PC · Simple Stub Filter For Suppressin~ TV Interference; LED Message Board, Pt.3 ; Electronics for Everyone - All About Electrolytic Capaci tors. June 1989: Touch-Lamp Dimmer (uses Siemens SLB0586); Passive Loop Antenna For AM Radios; Universal Temperature Controller ; Understanding CAO Probes ; LED Message Board , Pt.3 ; Coherent CW - A New Low Power Transmission Technique. July 1989: Exhaust Gas Monitor (Uses TGS812 Gas Sensor) ; Extension For The Touch-Lamp Dimmer; Experimental Mains Hum Sniffers ; Compact Ultrasonic Car Alarm ; NSW 86 Class Electrics; Facts On The PhaxSwitch - Sharing Your Phone Line With A Fax Machine . August 1989: Build A Baby Tower AT Computer; Studio Series 20-Band Stereo Equaliser, Pt.1 ; Garbage Reminder - A 7-day Programmable Timer ; Introduction To Stepper Motors; GaAsFet Preamplifier For The 2 -Metre Band ; Modern 3-Phase Electric Locomotives . September 1989: 2-Chip Portable AM Stereo Radio (Uses MC13024 and TX7376P) Pt.1 ; Alarm-Triggered Telephone Dialler; High Or Low Fluid Level Detector (uses LM1830N) ; Simple DTMF Encoder (uses Texas TMC5089) ; Studio Series 20-Band Stereo Equaliser, Pt.2; Auto-Zero Module for Audio Amplifiers (Uses LMC669) ; A Guide To Hard Disc Drives. October 1989: Introducing Remote Control ; FM Radio Intercom For Motorbikes (Uses BA 1404 And TDA7000) Pt.1 ; GaAsFet Preamplifier For Amateur TV; 1 Mb Printer Buffer· 2-Chip Portable AM Stereo Radio , Pt.2 ; Installing A Hard Disc In The PC ; A Look At Australian Monorails. November· 1989: Radfax Decoder For Your PC (Displays Fax, RTTY and Morse) ; Super Sensitive FM Bug ; Build A Low Cost Analog Multimeter ; FM Radio Intercom For Motorbikes, Pt.2 ; 2-Chip Portable AM Stereo Radio , Pt.3 ; Floppy Disc Drive Formats & Options; The Pilbara Iron Ore Rai lways. December 1989: Digital Voice Board (Records Up To Four Separate Messages, Uses Texas TMS3477NL and 256K RAMs) ; UHF Remote Switch ; Balanced Input & Output Stages ; National Semiconductor LM831 Low Voltage Amplifier IC Data; Install A Clock Card In Your PC ; Index to Volume 2. January 1990: Service Tips For Your VCR ; Speeding Up Your PC ; Phone Patch For Radio Amateurs; High Quality Sine/Square Oscillator; Active Antenna Kit; The Latest On Hig h Definition TV; Speed Controller For Ceiling Fans; Designing UHF Transmitter Stages. February 1990: 16-Channel Mixi ng Desk; High Quality Audio Oscillator, Pt.2 ; The Incredible Hot Canaries; Random Wire Antenna Tuner For 6 Metres; Phone Patch For Radio Amateurs , Pt.2 ; PC Program Calculates Great Circle Bearings . March 1990: 6 / 1 2V Charger For Sealed Lead-Acid Batteries ; Delay Unit For Automatic Antennas ; Workout Tim er For Aerobics Classes ; 1 6-Channel Mixing Desk, Pt.2 ; Using The UC3906 SLA Battery Charger IC; Digital Waveform Generation Using a PC ; The Controls On A Model Aircraft. April 1990: Dual Tracking ±50V Power Supply ; VO X With Delayed Audio ; Relative Field Strength Meter ; 16-Channel Mixing Desk, Pt.3 ; Simple Service Tips For Your Microwave Oven· Model Aircraft Aerodynamics; Active CW Filter For Weak Signal Reception. May 1990: Build A 4-Digit Capacitance Meter ; High Energy Ignition For Cars With Reluctor Distributors ; Th e Mazzie CW Transceiver; Waveform Generation Using A PC , Pt.3; 16-Channel Mixing Desk, Pt.4 ; What To Do When Your Computer Goes Bung , Pt.1 ; Electronic Load For Checking Power Supplies. June 1990: Multi-Sector Home Burglar Alarm ; Low-Noise Universal Stereo Preamplifier; Load Protection Switch For Power Supplies ; A Speed Alarm For Your Car; Design Factors For Model Aircraft ; Fitting A Fax Card To Your Computer; Off-Shore Oil Rigs ; What To Do When Your Computer Goes Bung, Pt.2 . July 1990: Digital Sine/Square Generator (Covers 0-500kHz); Burglar Alarm Keypad & Combination Lock; Simple Electronic Die ; Low-Cost Dual Power Supply; Inside A Coal Burning Power Station ; Weather Fax Frequency List; What To Do When Your Computer Goes Bung , Pt.3; Digital Waveform Generation Using A Computer, Pt.4 (PC Board Plus Software) . Note: November 1987 , December 1987 & January 1 988 are now sold out. AUG UST 1990 105 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. Wants a stopwatch for timing sports events I need a digital stopwatch for electronically timing radio controlled cars. Have you designed one? (F.J., Cabramatta, NSW). • We have not featured a digital stopwatch in the magazine and we are not likely to since commercial units with LCD readouts are available quite cheaply. Try your local Dick Smith Electronics or Tandy Electronics store. You can externally trigger the stopwatch functions on these units by carefully taking them apart and connecting wires across the appropriate switch contacts. Curing feedback with equalisation One of the thankless tasks I have in setting up our band is equalising the whole system and trying to get rid of the feedback. I have read many books and articles on the subject and of all the ways of eliminating feedback, no one way is a surefire method. No one seems to have addressed the problem head on. Killing the ignition with a relay I wish to install an ignition kill system on my VC Commodore automatic. Would it be OK to connect heavy duty relay contacts across the coil negative to chassis (ie, across the coil switching transistor), to short it out a_!ld __ so prevent starting of the engine. The unit would be used in conjunction with my alarm system. The VC Commodore has a bullet connector on the coil negative for connection of a tacho for timing purposes and I wish to use this to connect my 106 SILICON CHIP Even though we use good quality mikes, mixers, amplifiers and speakers, the elusiveness and possible damage to your hearing of feedback makes it very annoying, and not everyone appreciates pink noise at 100 watts! Has SILICON CHIP published any circuits for a sweepable notch filter or a parametric equaliser with a "Q" higher than 10? I envisage a unit with five .or more sweepable notch filters that would be separate from the third octave graphic equaliser, and when a note starts to ring to be able to tune it out without affecting the frequency bands either side. I enjoy reading your magazine and I especially appreciate the large number of projects in each issue. All the projects I have made are still working. The cartoons in the Serviceman's Log are a welcome touch. (S. P., East Fremantle, WA). • We have not published any circuits for notch filters or parametric equalisers. In any case, we doubt whether an array of these would really be effective in severe feedback situations. This is especially the case where you have performers moving about on stage and unit too. (P. J., Lurnea, NSW). • A relay connected across the coil negative to chassis will certainly prevent the engine from running and is unlikely to do any harm to the electronic components in the ignition system. However, the -short circuit must not be maintained for more than a few minutes if the ignition is left on. If this happens, the coil will seriously overheat and possibly burn out. The way to avoid this problem is to make sure that the kill circuit only operates for a few seconds at a time. This would be sufficient to stop the engine and will avoid harm to the ignition components. thereby continually varying the accoustic feedback possibilities. A better way of reducing feedback in this situation may be to frequency shift the whole signal slightly as was suggested in Wireless World magazine some years ago. Alternatively, it may be possible to accomplish the same result by feeding the audio signal through an acoustic delay line, similar to that used in the delayed VOX circuit published in the April 1990 issue of SILICON CHIP. Pity the passengers in model trains I am writing to recount my experiences with the construction of your Train Controller project (April & May 1988, SILICON CHIP) and to seek advice on several issues. I cannot consider myself an expert on electronics although I have had an interest in the subject for many years. I am also very interested in model railways and electronics features strongly in the powering and controlling of my layouts; ie, signalling, block detection & switching. I first purchased your magazine because of the Railpower controller project and have since taken out a subscription. I was impressed with the ease of construction and the easy-to-follow article which accompanied the project. Several points arise from this project: (1). The buzzer sounds when the unit is turned off. (2). No mention seems to be made of the use and setting for trimpot VR5. (3). The unit can be put into reverse from full speed ahead just by the flick of a switch which could conceivably damage the loco. (D. P., Beverley, SA). • We will answer your questions in order. First, it is quite normal for the buzzer to sound when the unit is turned off. Second, VR5 is a brake adjustment: it controls how fast the loco comes to a stop when the run/stop switch is put into the stop position. If you adjust VR5 for minimum resistance, the loco will come to a screeching halt when Sl is put into the stop position. On the other hand, if you adjust VR5 for a higher resistance, the loco will come to a mor e realistic and gradual stop. The problem of being able to put the loco into reverse from full speed ahead is present in most train controllers and was one we were fully aware of when we designed this circuit. However, having been prompted by your letter, we thought about the question some more and we have realised that it should be possible to design a lock-out circuit whereby the forward/reverse switch cannot be operated unless the throttle setting is zero. We will have a look at the possibility of incorporating this feature into the Railpower circuit in the near future. Kits for the SLA battery charger I am interested in building the charger for SLA batteries, as described in the March 1990 issue of SILICON CHIP. I was hoping you could tell me if a full kit is available. [L.K., Young, NSW). • Kits for this project are, or shortly will be, available from Jaycar Electronics and Dick Smith Electronics. Vive la difference in loudspeakers Hifi is moving on and it's probably time for electronics magazines to rethink their projects. We've had Vifa speakers coming out of our ears and stereo amps in an extraordinary variety, but I feel that you should offer projects more in keeping with current commercial offerings. I therefore suggest the following: (1.) Polk audio has introduced a speaker system with dual drivers, one of which cancels interaural crosstalk for a far wider possible stereo field. It seems to me it would be far simpler to stay with a single driven arrangement and do the job electronically - generate a dif- Yagis beyond the fringe I live about 100km away from the Melbourne TV towers (Ch. 2, 7, 9 & 10) which are all in the one direction, let's say at 12 o'clock on a dial. Our local channel (Ch. 8) is situated at 8 o'clock on the dial and is interfering badly with Channel 7 and sometimes with Channel 9. Filters were distributed to solve this problem which they did in many cases. My question is if I build accurate single channel antennas for Channels 2, 7, 9 & 10 and then diplex them to a single coax cable, what are my chances of improving the reception for each channel and of eliminating the Channel 8 interference? Our area is classified as fringe with prominent ghosts on Channels 7 & 9. By contrast, Channel 10 reception is excellent [which gave me that idea - I know that multiband Yagi antennas ference signal, roll it off above 6-BkHz, time-delay it by the appropriate amount, add it in correct phase to the original signal, stick it back into the tape input and there you have it! (2.) Get together with an Australian manufacturer and design a very small but high quality satellite system and a subwoofer, preferably with dual voice coils so that existing amplifiers could be used. You could then also design a 3-amplifier system (2 sets plus subwoofer) to complement it at a later date. And if you're really adventurous, use the now unused voice coil on your subwoofer to provide an error signal although I personally feel that fancy bass reflex a la Bose is probably a better way to go. Keep up the good work. (I. C., Surry Hills, NSW). • Thank you for your letter on the subject of hifi projects. We shall have a look at your suggestion for a loudspeaker system with electronic delay. We have had discussions with Australian manufacturers about the design of hifi loudspeaker systems on a number of occasions perform better on one channel and not so good on others). At the moment, I have a 13-element Yagi [Ch. 6-11 with corner ieflectors ). The use of head amplifiers is questionable because of the local channel. Could you also tell me the meaning of an octave of frequencies? [G. D., Morwell, Vic). • As far as single channel Yagi antennas are concerned, if you build a number of them, as you suggest, and then diplex them into a single channel, you run the risk that you will have just as much interference as with a multichannel antenna. Filters would still be required. A better solution would be to switch the various antenna signals. That way you would get better isolation of the interfering signals. An octave generally applies to music but can be used to describe any span of frequencies whereby the bottom frequency is half the top frequency. but they have not proved fruitful. We do hope for better results in the future. Why do amplifiers cause interference? I have purchased SILICON CHIP from November 1987 to the current issue and I have always looked forward to the next issue. I am an experienced technician of some 20 years. The technical query I have is why is there considerable noise - ie, buzz [not 50Hz or lO0Hz) - from power amplifiers in the medium wave and shortwave spectrum? It 's really severe. I've located the noise from the power amplifiers in the Nairn NAPl 10 and the SILICON CHIP Studio 200 [fitted with an AEM6005 module). I thought that 3 termin3.l regulators (78xx & 79xx) radiated enought noise in the MW band and 3MHz band, but the above amplifiers are far worse! Is the cure related to fitting .0lJ,tF capacitors across each rectifier diode? Please explain fully and cures. [D.B., Wollstonecraft, NSW). AUGUST 1990 107 Zero ohm resistors: a calibrated short circuit? I have enclosed with this letter several examples of some 00 (yes, zero ohm) resistors which I bought out of curiosity during a recent trip to Tokyo. Because of the language barrier between myself and the shopkeeper, I was unable to get any information about them. However, I am sure by his reaction that they are not just a gimmick. The shop was a legitimate electronic component supply shop. They came in a package which was labelled 00 (100 for $LOO) and they were displayed alongside all their other 1/4W resistors, arranged in correct sequence according to the resistance value. Maybe you or your rea ders can throw some light on the subject. As a further topic of interest, I • We assume that most of the noise radiated from power amplifiers would be due to the power supply and, more specifically, to the very fast turn on characteristics of the rectifiers feeding the large capacitor banks, typically 10,000µ,F or more. What happens is that the rectifiers turn on within a microsecond or so, every half cycle, to supply peak currents which may be 20 amps or more. This causes clipping of the 50Hz sinewave in the transformer secondary and this distortion (read: interference) is radiated directly by the mains wiring and also by the transformer core. The same problem occurs in large battery chargers but these a re even worse because the leads to the battery are directly radiating the rectifier hash. Also bad in this respect are all switchmode power supplies which essentially consist of just a rectifier (halfwave or bridge) and a filter capacitor directly across the mains. There is no easy solution to the problem and small capacitors 108 SILICON CHIP recently was going to buy a spare light globe for my microwave oven but was told by the local lighting shop that an ordinary (oven/pilot) light was unsuitable, as they did not last long in the microwave oven: Finally, I think an article on hearing aids may be of interest to readers, when looked at from the perspective of the technical problems they present and their (what I consider) high cost compared to other audio devices. (R. C., Avoca Beach, NSW). • Zero ohm resistors are commonly used on printed circuit boards instead of wire jumpers. We can think of no good reason why they should be used, except that they are possibly easier for automatic component insertion machines to handle. The comment about lights for microwave ovens is apparently correct and you do need to use the type recommended by the manufacturer. across each rectifier diode usually make the problem worse, or if they make it better in one section of the radio spectrum they usually make it worse in another band. lt may be worth experimenting with a small RF choke in series with each secondary connection to the transformer. Ideally this would have to be wound on a small toroid, otherwise the choke itself will radiate. Shades of the velvet action record player I have been a subscriber to your magazine for a couple of years now and enjoy all the articles, especially the vintage radio section. I need help on a repair job. Although I have been dabbling in electronics as a hobby for some years this "thing" has me beaten. It is a Philips Glidamatic stereo unit which consists of a radio (AM only) and a turntable. My problem is that the turntable works OK but the radio is dead. The power supply appears OK going to the tuner module (a semisealed unit) but very little voltage is coming out - only a few microvolts. At the two dial lamps (12V), there is only a faint glow and my DMM shows only 0.43 volts. This is a "love job" that I am doing with no circuit diagram. So if anybody can help me I would be most appreciative. The amplifier uses AD161 /162 transistors and is of 1965/66 vintage. If anyone has a circuit diagram I would willingly purchase same or copy of same. (John Winchester , 1 Fairmont Drive, Wauchope, NSW 2446). From the golden age of wireless First of all I would like to convey my appreciation for the articles on vintage radio. Although not heavily into it, I find them very interesting, partly because valve radios were part of my youth (the older models of course). Anyway keep up the good work. I should note that my interest is more than nostalgia, which leads me to my question. If you or one of your readers could help it would be most appreciated. I am interested in obtaining a manual or circuit diagram of a Healing Golden Voice Model S401E portable valve radio. My compliments also for the rest of the magazine, except the Computer Bits: I am bored by the endless articles on IBM PCs. It's about time the media realised that the IBM PC is not the centre of computing but that computing is the centre and IBM, like Apple, Amiga, Sun etc, orbit this kernel. (R. Payne, 2 Valerie St, Noble Park, Vic 3174). • We hope that one of our readers can help you with the service information you want. Notes & errata Phone Patch, January 1990. There are three errors on the PCB wiring diagram shown on page 3 2: (1) the resistor connected to pin 10 of IC2 should be lOOkO (not lOkO); (2) the lµF capacitor connected to pin 17 of ICl is shown with reversed polarity (the negative lead should go to pin 17); and (3) D7 is shown with reversed polarity (the cathode should go to the base of Q6). ~ Don't miss a single issue IF YOU'RE THE KIND OF READER that can't wait to get the next copy of SILICON CHIP, then why not have the magazine delivered direct to your door? Each month, we'll bring you the best and brightest electronics magazine in the business, put together by Australia's most experienced team. Here's what to look for in each issue: *ForConstructional Projects The Enthusiast *& Projects Amateur Radio: Theory * The Serviceman's Log *TheComputer Bits: Getting Most From Your PC *Fascinating Vintage Radio: A Hobby 24 Hour Fax Service Toda y Jue by filJio lbaiJ·10 g out aod su& !' this - ____s_c_r_•.:P~t:i:o:o~ coupoq r----------------------Freepost * Subscription Coupon (02) 979 6503 Send the coupon with your Credit Card details. 24 Hours, 7 Days a week. Subscr·L □ □ New subscription Renewal Start in _ _ _ _ _ __ Name_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __ (PLEASE PRINT) Subscription Hotline Telephone (02) 979 5644 9am-5pm Mon-Fri and quote your Bankcard, Visa Card or MasterCard No. and expiry date. Detach Coupon and Mail to: FREEPOST 25 SILICON CHIP PUBLICATIONS PO BOX 139 COLLAROY BEACH NSW 2097 *No postage stamp required in Australia. Street._ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __ Suburb/town _ _ _ _ _ _ _ __ _ _ _ Postcode _ _ __ 1 year (12 issues) □ $A42 Australia 2 years (24 issues) □ $A84 NZ & PNG (airmail) □ $A65 □ Overseas surface mail □ $A62 □ $A130 Overseas airmail □ $A120 □ $A130 $A240 Enclosed is my cheque/money order for $ _ _ _ or please debit my □ Bankcard Card No. □ Visa Card □ MasterCard I I I I 11 I I I 11 I I I 11 I I I I Signature _ _ _ _ _ __ __ Card expiry date_ _ / __ L-----------------------J Cash in your surplus gear. Advertise it here in Silicon Chip. CLASSIFIED ADVERTISING COUPON ANTIQUE RADIO Advertising rates for this page: Classified ads - $7.00 for up to 15 words plus 40 cents for each additional word; Display ads (casual rate) - $20 per column centimetre (max. 10cm). Closing date: five weeks prior to month of sale. If you use a PO Box number, you must include your permanent address and phone number for our files. We cannot accept ads submitted without this information. To run your own classified ad, put or.e word on each of the lines below and send this form with your payment to: Silicon Chip Classifieds , PO Box 139 , Collaroy Beach, NSW 2097. ANTIQUE RADIO RESTORATIONS. Your one-stop electronic repair shop. Specialising in restoring vintage radios including chassis rewiring , quality new parts, valves , valve sockets, speakers, transformers , cabinet restoration . Quality secondhand radio dials & parts for most brands & models. About 400 radios in stock for restoration & parts. Every restored wireless is covered by a 2-year warranty on parts & service. French polishing of timber cabinets available. Vintage car radios in valve & transistor types available for restoration. Repairs done on tape decks , amplifiers, TVs & videos. Open Sat. 1Oam-5pm; Sun . 12 .30-5pm. 109 Cann St, Bass Hill, NSW 2197. Phone (02) 645 3173 BH or (02) 726 1613 AH. PLEASE PRINT EACH WORD SEPARATELY, IN BLOCK LETTERS 2 3 4 5 6 7 8 9 10 11 12 13 14 15 ($7.00) 16 ($7.40) 17 ($7 80) 18 ($8.20) 19 ($860) 20 ($900) 21 ($9.40) 22 ($9.80) 23 ($1020) 24 ($10 60) 25 ($11 00) 26 ($11.40) 27 ($11.80) 28 ($12 20) 29 ($12.60) 30 ($13.00) 31 ($13.40) 32 ($13.80) 33 (14.20) 34 ($14.60) 35 ($15.00) 36 ($15.40) 37 ($15 .80) 38 ($16.20) 39 ($16.60) 40 ($17.00) 41 ($17.40) 42 ($17.80) 43 ($18.20) 44 ($18.60) 45 ($19.00) 46 ($19.40) 47 ($19 80) 48 ($20.20) 49 ($20.60) 50 ($21 00) 51 ($21 .40) 52 ($21.80) 53 ($22.20) 54 ($22.60) 55 ($23.00) 56 ($23.40) 57 ($23 .80) 58 ($24.20) 59 ($24.60) 60 ($25.00) Name. Street Postcode Suburb/Town Enclosed is my cneque or money order for $ ........... .. ..... .. .. ..... .. ...... or please debit my D Bankcard Card No lL D Visa Card D _ _ _ L _ L _ __ L ___L__ _ l _ - - - '- Signature .. MasterCard j _ _ _ L __ L_ _ _ L _L _ _i ___L__ _ L _ - - - ' _ _ J SILICON CHIP DIGIT AL WAVEFORM GENERATION: as described in SILICON CHIP in March , May, June & July 1990. PC board and software to generate waveforms. Both for only $39.95 including p&p. Instructions included. PC Board $16.00, Software $32.50 including postage . Send cheque or money order to M. Radvanyi, PO Box 49 , Kingswood , NSW, 2750. BELT KITS FOR VCRs. Please supply brand & model number & $1 2. 00 for each kit required. Prompt dispatch assured. James Cotterill, PO Box 44, Farrer, ACT 2607 . EPSON PB0 PORTABLE battery rechargeable 80-column printer. Serial interface. Very compact & light. 1 .1 kg. Uses normal or thermal paper. $1 7 5 . Import Technologies (07) 372 5138. TOSHIBA LCD SCREEN. Originally to suit T1500 desktop. 240 x 180mm, 640 x 200 pixels. Uses 5V supply & TTL drive signals. Suit experimenter. $150. Import Technologies (07) 372 5138. . Card expiry date ...... ./ .. .... . . FAX THIS COUPON WITH YOUR CREDIT CARD DETAILS TO (02) 969 6503 110 FOR SALE KITS AVAILABLE FOR the ETI Digi125 $17.95 plus $2 .50 p&p. Heatsink not supplied. Kits built and repaired. u, a., -~ ...0 ·01 0 C u ..c (.) (I) a., 00 ·s Cl) W IC of ._ :E w "5 oo :C IC o. -:C () (.) t- ~ a: a., (.) -~ a., Cl) SIMM MODULES 1 Mb X 9 0 ... ~ ·;: ..c '- 0 ~ 0 ~ >-0 ~ ..c ro SMARTWORK POST-PROCESSOR: if you own a HP? 4 75 or compatible flat bed plotter you can plot your own PCBs direct on blank board ready to etch. PP plots 1: 1 and mirror image. Only $99. PC Computers (08) 332 6513. GENERATOR, Model and square wave out1 MHz. Atennuator steps. As new. $260 969 2160 . WEATHER FAX programs for IBM XT/ATs * * * "RADFAX2" is a high resolution, shortwave weather fax, Morse & RTTY receiving program . Needs CGA, SSB HF radio & Radfax decoder . Also "RF2HERC", " RF2EGA" & " RF2VGA", same as RADFAX2 but suitable for Hercules, EGA & VGA cards respectively. $35. * * * "SATFAX" is a NOAA, Meteor & GMS weather satellite picture receiving program . Uses EGA & VGA modes, needs EGA or VGA colour monitor & card, plus "WEATHER FAX" PC card. $45. * * * All programs are on 5.25-inch or 3 .5-inch discs (state which) & include documentation . Add $3 postage . ONLY from M. Delahunty, 42 Villiers St, New Farm , Qld 4005. Phone (07) 358 2785 . UC3906 IC SOFTWARE: from the author of the SLA Battery Charger in SILICON CHIP , March 1990. Allows you to quickly design a charger for any SLA battery between 4V & 30V. Available on 5.25-inch 360K disc for IBM XT/AT (GWBASIC required), C64/C16, Apple II (FPBASIC required) with instructions. $19.95 each (please specify computer) . Only from D. Yates, PO Box 134, French's Forest, NSW 2086 . See SILICON CHIP, Jan. 1990 COMPLETE KIT ........... $59.00 BUILT & TESTED ..... .. $119 .00 CASE .. .... ........... .... .... $10.00 sons $10.50 DRAM 256K X 4 80ns $1 0.50 cO FUJITSU MEMORY CHIPS Prices at July 8th Speed CHIP TYPE 100ns sons ?Ons PRICE EX TAX SIMMS 9x256 9x1mb (MACS) 8x1 mb (IBM) 9x1 mb PS2 9x4mb" SIPPS 9x256 9x1mb DIP 411000 414256 41256 41464 (256) 4164 ZIP 414256 (1mb) 41256 411000 (1 mb) 440 0 (4mb/ 29.50 97. 00 31. 00 99.00 94. 00 36.00 115.00 99.00 650.oo· 31. 00 99.00 9.85 9.85 2.80 2.9 0 36.00 115.00 10.60 10.60 3.20 9.85 10.60 150.00 29.50 9.40 9.40 2.65 2.75 2.50 9.40 2.70 9.40 9.85 65.00 Sales Tax 20 1/,. Overnight delivery. Credit cards welcome Phone for pricing on 60ns, Toshiba , Compaq & Laser Printer PELHAM Tel (02) 427 0011 Fax (02) 418 6831 FIX-A-KIT $20 PER HOUR LABOUR NO CHARGE FOR KITS THAT CAN'T BE REPAIRED 3 MONTHS WARRANTY ON REPAIRS CONSTRUCTION AVAILABLE HYCAL INSTRUMENTS DESIGN, MANUFACTURE, REPAIR OF ELECTRONIC EQUIPMENT (02) 633 5897 JILOA (TECHNIKIT DIV.) ACTIVE SHORTWAVE ANTENNA DRAM 1 Mb X 1 PHONE : 02 481 0065 : 02 484 4460 FA X 3:. 6i. Repairs to radio control toys. Model railway projects designed and built. Prototype and production board supplier to the hobbyist. Supplier of PCBs for projects in SILICON CHIP. Electronic Toy Services (08) 382 8919. · $115.00 PACIFIC MICROELECTRONICS PTY. LTD. ' CENTRAL PARK" UNIT A20, 4 CENTRAL AVENUE, THORNLEIGH N.S.W. 2120 0 _g c son s • Add 20,c: Sales Tax / SS. 00 P & P .:,::_ (I) u, (.) ~::, 2C E en LEADER AUDIO LAG-120A. Sine put. 1 0Hz to -50dB in 1 0dB ono. Phone (02) of Computers the Quality you expect .. -t jjj ~ -a3 f- C - From Japans Largest Manufacturer C: 0 Ol C MEMORY IC' s & SIMM"s C'• Cl) LOOP ANTENNA KIT .. ... ..... ........ ... .. .. $44.00 FULLY BUILT ........ .. $69 .00 Improve signal strength & signal quality in a portable tunable antenna. BOX 73, GLENHUNTLY, VIC. 3163 (03) 571 6303 MY AUSTRALIAN DESIGNED low cost super fast Z80 micro-controller development system has gained acceptance already with educational institutions . Pop it on the end of any PC MSDOS or Z80 machine and away you go. Boards, EPROM and 360K disk $76 including postage for a short form kit. Gee , I wish I had this when I was a kid. For more info. send a 41 c stamp to: Don McKenzie, 29 Ellesmere Crescent, Tullamarine 3043. LOGIC ANALYSER. Gould Instruments K40 stand alone analyser. Eight nonvolatile memories, ?-inch CRT, 4 x 2K sample memories, 2 x 16-channel, probes up to 100MHz, asynchronous capture. Weighs 7.7kg . $975.00. Import Technologies (07) 372 5 138 . PROJECT PCBs: ETI-DIGI 1 25 audio amp $9/pair, ETl-1623 IBM PIA card AUGUST 1990 111 -~---------------------, FREEPOST SUBSCRIPTION COUPON To: Freepost 25, Silicon Chip Publications, PO Box 139 Collaroy Beach, NSW 2097, Australia. NO POST AGE ST AMP REQUIRED IN AUSTRALIA. □ Start in _ _ _ _ _ _ __ 0 Renewal New subscription Name _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __ (PLEASE PRINT) Street _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __ __ Suburb/town _ _ _ _ _ _ _ _ _ _ _ _ _ Postcode_ _ __ 1 year ( 1 2 issues) D $A42 Australia NZ & PNG (airmail) 0 Overseas surface mail D $A62 D $A 1 20 Overseas airmail 2 years (24 issues) D $A84 D $A130 D $A130 D $A240 $A65 Enclosed is my cheque/money order for $ _ _ _ _ or please debit my ~ Bankcard Card No. U Visa Card L_I-'--'------'-I__,I I D MasterCard I ]I I I~~~~ Signature _ _ _ _ _ _ _ _ _ _ _ Card expiry date _ __,___ L---------------------~-J ,k---------------------, SILICON CHIP BINDERS Yes 1 Please send me _ _ __ SILICON CHIP binder(s) at $A11.95 plus $ A3 p&p each (NZ p&p $A6) Name _ _ _ _ _ _ __ _ _ _ _ __ _ _ _ __ _ __ (P LE AS E PRI NT) Street _ ____ _ _ _ _ _ _ _ __ _ _ _ __ _ _ __ Suburb/town _ _ __ _ _ _ _ _ _ _ Postcode _ _ _ _ __ Enclosed is my cheque/money order for $ _ _ __ or please debit my Advertising Index Adroit Electronics .. .......... .. 111 Altronics ..... ..... ..... ... ...... 61-65 Arista .......... .... ... ...... ... ...... ... 5 Aust-Tek Electronics ........... . 8 1 Automatic Alarms ... ..... .... .... . 25 Back Issues .. ........ ..... 104 ,105 Board Solutions .... .. .... .... 7 3- 7 5 David Reid Electronics ...... IFC , 1 Dick Smith Electronics .... . 10-1 5 Electronic Solutions .... .. .. 86,87 Elmeasco .... .... ..... ......... 25 ,81 Force Electronics ...... .. .. ..... . 23 Geoff Wood Electronics ...... 1 03 Harbuch Electronics ... .......... 4 7 Hycal Instruments .. .... ..... ... 111 Jaycar Electronics ..... .... . 28-31 92 -95 Jiloa ... ... ... .. ......... ...... ... .... 111 J.V. Tuners ..... ..... ... ...... ... .. . 47 Oatley Electronics ... .. ..... ... .. 27 Pacific Microelectronics ...... 111 PC Marketplace .... .... ... .... .. . IBC Pelham ... ...... ...... .. ........... 111 Philips .. .... .... ... ... ... ... 35 ,37 ,39 Protel ... ...... ....... ... ..... ..... .... 79 RCS Radio . . . . . . . . . . . . . . . . . . . . . . . . . 91 Resurrection Radio ....... ...... ... 9 Rod Irving Electronics ..... 40, 4 1 44,45,98 ,99 Sheridan Electronics ...... ... ... 91 Silicon Chip Binders ..... 51,OBC Sound Australia ........ ............. 9 Subscriptions ......... ...... .... . 1 09 Tech-Fast .. ... ..... .... ....... ... ... 59 Westinghouse .. .. ....... ..... ..... 1 9 I I Bankcard I J Visa Card CJ MasterCard PC Boards Signature _ _ _ _ __ __ __ _ Card expiry date_~-- L _______________________ J $39 . 95 , 6502 / Z80 / 6809 miniprocessor $49 . PRE-BUil T AUDIO AMPS: 3 .5W LM380 $20, LM1875 $30, 150W IC-150 $99, 300W IC-300 $179, 60W Valve-1 $99, 200W Valve-2 $199, AudioToolkitTool-1 $69, FET-1 super quality stereo preamp $20, Bass & Treble $23. ROBOTICS: experimenter's kit. Includes IBM-PC controller, PSU, stepper motor, manual, software $99. 112 SILICON CHIP Digital voice recorder TMS-334 7 chips $25. PC Computers, 36 Regent St, Kensington, SA. Phone (08) 332 6513. TOSHIBA T3100 CO-PROCESSOR kit. This piggy-pack board enables the fitting of a 80287-8 to the early T3100 . Two types available, solder in & plug in. Solder version $190.00. Plug-in version $335.00. Import Technologies (07) 372 5138. Printed circuit boards for SILICON CHIP projects are made by: • Electronic Toy Services, 2/111 Glynville Drive, Hackham West, SA 5163. Phone (08) 382 8919 . • Jemal Products, 5 Forge St, Welshpool, WA 6106. Phone (09) 350 5555. • Marday Services, PO Box 19-189, Avondale, Auckland, NZ. Phone 88 5730. • RCS Radio Pty Ltd, 651 Forest Rd, Bexley, NSW 2207. Phone (02) 587 3491. NEW! NEW! NEW! PRODUCTS AND HUGE SAVINGS! SPEED UP YOUR OLD XT WITH A NEW MOTHERBOARD 31 MHz XT MOTHERBOARD INPUT/OUTPUT LANDMARKS AT STAGGERING 31 MHz: 12MHz XT MOTHERBOARD e • • • • • e e CPU-Ultra high speed V20 Clock speed 12MHz, 0 Wait State memory access 4.77112MHz Hardware/Software, selectable Use advanced VDL-C1 system control chip to reduce the chip count and increase the speed and reliability Wait State for memory and VO (On-board/External) are programmable by Hardware/Software 8087 co-processor socket and 8 VO expansion slots 512 KB/640KB/1024KB on board (384KB virtual disk) If purchased with IBM RAM, included is: utility disk, which contains software drivers to make use of the 384KB (1024KB moclel only) for RAM Disk, Hard Disk Cache and Printer Buffer etc. Motherboard only $125 Motherboard plus 640k $250 Motherboard plus 1MB $300 Out performs PS II model 50 Comes with utility software to allow you to use additional memory as print spooler, disk cache or virtual disk. Cannot use old RAM (ie 41256) too you get the whole lot for an incredibly low $395 Fixed Bracket - Com patiable 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 on board 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 +5V/ + 12V power supplies from PC - All pin-signal assignment of PC-bus are clearly marked on slot No 4 for easy testing/monitoring Dimension:208mm x 145mm x 4tmm (L x W x H) Weight :1040gm net Material :Aluminium alloy Keyswnch :Two-posnion pull CAM switch Buzzer :Pulse sound LED :Power ON (Green) steady: HO R/W (Yellow) trigger :Alarm (Red) pulse Made of heavy duty alluminium alloy Security key for locking Warning alarm for indicating wrong operation LEDs for indication R/\N operation and system status Easily assembled into the case Includes 1 X H3636 removeable bracket H3635-WAS $179 NOW$125 Removable COMPUTER PART# SIZE AMIGA AMIGA AMIGA AMSTRAD ATARI ATARI IBM IBM IBM IBM IBM PSII IBM PSII D2930 D2932 D2938 D2904 D2916 D2918 D2946 D2948 D2950 D2952 TOSHIBA TOSHIBA ZENITH ZENITH COMPAQ COMPAQ NEW NEW 880K 360/880K 880K 720K 720K 36on20K 720K 1.4MB 360K 1.2MB 360K 1.2MB D2970 D2972 D2976 D2978 D2980 D2982 5.25" 5.25" 5.25" 5.25" 5.25" 5.25" 360K 1.2MB 360K 1.2MB 360K 1.2MB PHONE (02) 418 6711 FAX (02)4186713 Mail Order Address: P.O. Box 1100 Lane Cove NSW2066 ONLY $90 • ~~"j's~ ~~~r~;:i;rrupt Gameport Cables and manual included NOW$62.50 SAVE50% r PROTOTYPE DEVELOPMENT CARD Designed for the PC add-on card designers as an excellent alternative to pure breadboard card for developing prototype of add-on cards. The built-in basic circuit can eliminate the heavy labour and time J ~~~~~:in3..c=~.s a~~~~~~J'.J:~ed~(~ li~~~uWe~ma"ni address line buffer. 8 I/O wrne control signals and 8 I/O read control signals are also provided for easy implementation of the I/O R/W registers. FEATURES Built-in basic circuit for a great deal of time saving Large breadboard area (32110 holH) for do-it-yourself circuits All bus signals are buffered, marked and ready for use Independent on-board memory and VO address decoders Jumper Mlectable memory and 1/0 addreusizes 37 Pin D type connector ready for various applications APPLICATIONS Prototype development kit for PC add-on cards Customized PC add-on cards ONLY $110 SAVE 25% M5885-WAS$149 NOW COMMENTS CAPACITY 3.5" 5.25" 3.5" 3.5" 3.5" 5.25" 3.5" 3.5" 5.25" 5.25" 5.25" 5.25" Pfii[ (jfeeson 's SAVE 30% Dimension:206mm x 117mm x 41 mm (L x W x H) Weight :215Qm net (w/o hard disk) Material :Plastic Capacity :3.5' ha~-height disk ST506/412 interface type Transferable to another computer system Convenient for transport and storing H3636 - WAS $129 NOW • ~r:!~:~~~r-:~:~~~ M5865 - WAS S125.00 EXTRA VALUE!!! If you buy IBM RAM utilities disk .... Parallel printer port RS232C serial communication port {expandable to two by user • • $225.00 TRANSDATA 3.5" Hard Disk Assembly SLOT EXTENSION KIT Mss9o- BACK IN STOCK! ONLY $199.00 • • • • WITH ON/OFF SWITCH WITH ON/OFF SWITCH INTERNAL KIT FOR A2000 FOR PC1512/1640 WITH POWER SUPPLY SWITCHABLE, WITH POWER SUPPLY WITH ADAPTER INTERFACE & CABLE WITH ADAPTER INTERFACE & CABLE WITH ADAPTER INTERFACE & CABLE WITH ADAPTER INTERFACE & CABLE WITH ADAPTER INTERFACE & CABLE WITH ADAPTER INTERFACE & CABLE SUIT TOSHIBA LAPTOP SUIT TOSHIBA LAPTOP SUIT ZENITH SUPER SPORT SUIT ZENITH SUPER SPORT SUIT COMPAQ SLT 286 SUIT COMPAQ SL T 286 PERSONAL COMPUTER MARKETPLACE FREIGHT CHARGES Include $10 with order for all normal items - heavy items, e.g. monitors add $Hi. 14 day money back guarantee Order by phone (use credit card). by fax or by mail. Unless insurance is declined it will be charged at 1% of total purchase. This is for your protection. PRICES VALID AT 1 JULY 1990 PtvLtd PRICE 249.00 299.00 229.00 269.00 269.00 299.00 299.00 329.00 299.00 329.00 399.00 449.00 349.00 399.00 349.00 399.00 349.00 349.00