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(3/16,7 / 32,1/4,9 / 32,5/16. 11/32,3 / 8,7 / 16,1/2'). * 1pc. 1/4" socket adaptor. * 1pc. bit adaptor. * 1pc. 90 deg. adaptor. NYLON CALIPER * 150mm only $19.95 only $4.95 David Reid PH: (02) 267 1385 127 York St. SYDNEY 2000 Electronics P.O. Box Q103, SYDNEY 2000 FAX: (02) 261 8905 ~ c~~ [-1 SAME DAY MAILORDER DESPATCH* - Dme,,C/JJb /nJmtanoltllf ·. \' · · I I Post and Packing $5 - $25 ........ $3.00 $26 - $SO ...... $5.00 $SI - $100 ...... $6.00 49 . :~~o-! .9..::::.%~i l. !I · · ·, • June 1991 FEATURES 6 Electric Vehicle Transmission Options by Gerry Nolan It all depends on the driving cycle 14 Tuning Into Satellite TV by Garry Cratt The basics of satellite TV reception PROJECTS TO BUILD YOU CAN SAVE money by building your own high performance UHF TV antenna. This corner reflector design has high gain on both UHF bands IV & V, and has a narrow vertical acceptance angle to reduce interference effects & ghosting. Details page 24. 24 A Corner Reflector Antenna For UHF TV by Leo Simpson Easy to build unit covers both Band IV & Band V 36 Four-Channel Lighting Desk, Pt.1 by John Clarke& Leo Simpson , For theatres, discos & music groups 59 Howl Suppression For PA Systems by Darren Yates An experimental frequency shifter 64 13.5V 25A Power Supply For Transceivers, Pt.2 by John Clarke Full construction & testing details SPECIAL COLUMNS 54 Serviceman's Log by the TV Serviceman Whistle's aren't always carefree 74 Computer Bits by Jennifer Bonnitcha How to use the keyboard enhancers 78 Vintage Radio by John Hill THIS 4-CHANNEL LIGHTING desk boasts a host of operating features & can control lamp loads rated up to 3600 watts. The first article starts on page 36 & gives all the specifications & circuit details. Restoring a 4-valve Howard receiver 88 Amateur Radio by Garry Cratt Active filter improves CW reception Special Notice DEPARTMENTS 3 Publisher's Letter 4 Mailbag 32 Circuit Notebook 53 Bookshelf 84 Product Showcase 90 Back Issues 2 SILICON CHIP Ask Silicon Chip Notes & Errata Subscription Page Market Centre 96 Advertising Index 92 93 94 95 SPACE RESTRICTIONS this month have prevented us from publishing Bob Young's remote control column, Jim Lawler's second article on installing multiple TV outlets & Bryan Maher's article on electrical energy. We hope to publish these three items in the July 1991 issue of SILICON CHIP. Publisher & Editor-in-Chief PUBLISHER'S LETTER Leo Simpson, B.Bus. Editor Greg Swain, B.Sc.(Hons.) Technical Staff John Clarke, B.E.(Elec.) Robert Flynn Darren Yates Reader Services Ann Jenkinson Advertising Manager Paul Buchtmann (02) 979 5644 Mobile: (018) 28 5532 Regular Contributors The North Head UHF translator: much ado about nothing Just over a year ago, in the March 1990 issue of SILICON CHIP, I wrote a "Publisher's Letter" commenting on the controversy over the UHF translator at Sydney's North Head. For many years, residents of Sydney's beachside suburbs have been waiting for this installation so that they could at last enjoy ghost-free and noise free TV reception . This month, the North Head UHF translator is scheduled to go into operation. We sincerely hope it does, partly because this issue features a UHF corner reflector antenna which we think will be a timely project. It seems as though all the conservationists who protested about the installation have finally had their fears allayed (or have gone on to oppose other developments) and the project has come to fruition. But consider what an enormous waste of time it has all been. The North Head UHF translator was first planned in the mid-seventies and should have been in operation shortly after the Kings Cross UHF translators were installed. Has the project benefitted from the delay? Of course not and neither have all the viewers who have waited all these years. Which means there are some lessons to be learnt. For their part, people concerned about the environment should not mindlessly oppose every new development on the vague premise that some animal habitat or the quality of life will be destroyed. That leaves them open to the latest politicians' epithet of "greenie" or worse, "ratbag greenie". Second, any company or organisation planning a large development should do their homework and make sure that all the pros and cons are fully explained to the public. If that is not done, there is bound to be a hue and cry. Interestingly, while the North Head UHF translator was subject to a lot of opposition, what about all the antenna towers for the burgeoning cellular telephone networks in every Australian city? They have gone in with hardly a ripple. And let's face it, they are ugly and they're often right in the middle of prime residential areas. As far as I am concerned, if the cellular telephone towers can go ahead without problems, there is no real reason why all the other planned UHF translators for Sydney's difficult reception areas can't be installed without further delay. Don't you agree? Leo Simpson Brendan Akhurst Jennifer Bonn itcha, B.A. Garry Cratt, VK2YBX John Hill Jim Lawler, MTETIA Bryan Maher, M.E., B.Sc. Jim Yalden, VK2YGY Bob Young Photography Stuart Bryce Editorial Advisory Panel Phi lip Watson, MIREE, VK2ZPW Norman Marks Steve Payor, B.Sc., B.E. SILICON CHIP is published 12 times a year by Silicon Chip Publications Pty Ltd. All material copyright ©. No part of this publication may be reproduced without prior written consent of the publisher. Printing: Magazine Printers Pty Ltd, Alexandria, NSW; Macquarie Print, Dubbo, NSW. Distribution: Network Distribution Company. Subscription rates: $42 per year in Australia. For overseas rates, refer to the subscription page in this issue. Liability: Devices or circuits described in SILICON CHIP may be covered by patents. SILICON CHIP disclaims any liability for the infringement of such patents by the manufacturing or selling of any such equipment. Editorial & advertising offices: Unit 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 ] UN E 1991 3 MAILBAG Le specs for le tuner I have been following the AM Stereo Tuner series with great interest and have been just wracked with suspense waiting to see "le specs". Does it seem over presumptuous to expect some figures if, as you say, we are to line this unit up alongside our otherwise you-beaut gear? I happen to like a lot of AM program material but my TX 530 Yamaha FM tuner, like most, does not seem to make allowances for my taste, 'cos it doesn't have a stereo AM section. But I'm blowed if I'm going to drop $200 for a medium-fi front end that does memory tricks. Don't get me wrong, I'm not rubbishing your efforts; I just want an idea of what to expect. You gentlemen have never disappointed me yet with your projects and I speak as one who has been doing it for many moons. Nevertheless, I would like to know - as would many others, I'm sure. P. Sherwood, Nerang, Qld. Le specs are as follows: frequency response to BkHz at the -3dB point; signal/noise ratio >60dB; THD < 1 %; and separation between channels typically 30dB or better. Subjectively, the tuner sounds every bit as good as typical FM stereo tuners. Customer service often neglected I can only agree with your Publisher's Letter in the April issue. I would add that the problem you outline is not restricted to hobbyists. Plasma Physics is not a bulk buyer of electronic parts and I often find that suppliers are not interested unless we can raise an order of $50-$100. Often this is hard to justify when all you want is five devices that you might use over a one or two-year period. For this reason some of the slightly more exotic, and very useful, devices are denied us. The problem is compounded by the fact that most parts come from overseas and local suppliers are rather coy about keeping high performance (and 4 SILICON CHIP SILICON CHIP, PO Box 139, Collaroy Beach 2097. high'er priced I suppose) parts in stock, so most of us cannot use them without buying $100 worth. Thus, there appears to be no market for them and all this helps to keep the prices high and the bits hard to get. I reckon that many parts from manufacturers such as Burr-Brown, Analog Devices, Precision Monolithics, Linear Technology, etc would remain virtually unknown and unobtainable except that RadioSpares Components stock some. The manufacturers' local agents often do not seem very interested in doing it. I get the impression that local suppliers do not understand the meaning of service, of creating a market or competing, and all things considered would rather not be in business. These are, of course, generalisations but a cynic could be excused for thinking that the reason local companies get these agencies is because it looks good in their front window and in their advertising blurb. Often, the way parts are advertised is very poor too, with many agents and suppliers being quite ignorant of what they are selling and what they could be selling. They will get little sympathy from me. I'll get off my soapbox now. P. Denniss, Dept of Plasma Physics, University of Sydney. By the way, this fax was sent to your office using an AT-compatible fitted with a Netcomm Fax-card direct from a word processor. J. Harvey, Port Macquarie, NSW. We are not keen to take on a fax switch as a project. Commercial units are very complex and need to be, to take into account all the combinations of fax and STD tones, and the various Telecom switching requirements. For your reference, we reviewed a PhaxSwitch in our July 1989 issue and also a Fax Card in June 1990. Microfiche copies would be desirable I would like to make a suggestion for your magazine. I think it would be good to produce a special (probably subscription only) version which at a premium price ($1-$4 per issue greater than the standard) would also include a microfiche copy of the magazine. I think this would be very much liked by corporate type subscribers. Microfiches take up so much less room than paper magazines. I don't know the profile of your magazine purchasers and whether this would be a viable option or not. I wouldn't mind a microfiche version though. R. Plant, Belgrave Heights, Vic. Fax switch as a project Firstly, let me congratulate you on your excellent magazine. May it continue for many years to come. As a suggestion for a project could you develop a fax switch? I feel this would be very well received by many of your readers (including me) when you consider the large number of fax machines that are now in use. Many of these are used in domestic and small business situations where the cost is most important and consequently, to save a few dollars, a fax with manual switching is purchased. A project such as this would make an upgrade less expensive than purchasing a new fax machine. AM stereo needs a re-launch I was delighted to see our station's callsign, 1269, featured in the recent series of articles on your wideband AM stereo tuner. Thank you, even though it may have been a coincidence! We have discussed many times the failure of AM stations which have converted to FM and the sad state of so:q:ie AM operators. Unfortunately, AM is generally treated as the poor cousin in the broadcasting business. It would indeed be a boost if the industry was to relaunch AM stereo and this time around, do it properly! Ken Sparkes, Station Consultant, Radio 2SM, North Sydney, NSW. MAINS FILTER SPECIAL Comments on the low ohms tester I have just completed the "Low Ohms Tester for Digital Multimeters" published in the February 1988 issue of SILICON CHIP and I am quite pleased with its performance. May I suggest some improvements though. After adjusting the offset on the xlOO range, there was a significant reading on the xlOOO range. This is due to the drop in the wires between the board and the Rx terminals now carrying lOmA. The solution is to take separate wires to the Rx terminals for the current circuits and for the amplifier input circuits. This is easily achieved by cutting the printed wiring around the earth side of the lOOQ resistor and providing a bridge for the printed wiring around it. It would have been desirable if we could say that any reading greater than 3V is beyond the measuring range of the instrument. At present, however, an anomaly exists on open circuit on the xlOO & xlOOO ranges because the meter is measuring the difference between the positive Rx terminal and amplifier output which both reach towards 5V when Rx is open. This would not have occurred if the meter was measuring the amplifier's output to ground. To achieve the 100:1 ratio would require parallelling the 10kQ resistor with a lMQ resistor. The low scales switch side would need to be rewired to accept a negative polarity reading or alternatively make use of the third set of contacts on the rotary switch. V. Erdstein, Highett, Vic. Full steam ahead for model sound effects Over the Easter break, I breadboarded Darren Yates' SteamSound Simulator featured in April's SILICON CHIP just to see what it sounded like. I can only use two words to describe it: simply brilliant! I had to use the modified version because the "track" voltage (variable, of course) was derived from a 2kQ pot connected across +12V and earth. The setting of the lOkQ pot at the base of Q2 gave some interesting effects; eg, at one setting, with a low "track" voltage (about 2V), there would be a fair amount of white noise, then as the "track" voltage was wound up it would die down just before the chuffing began; or the lOkQ pot could be adjusted so that at low "track" voltage the white noise would be at this quieter level. Thanks for a great magazine. I always enjoy the "Serviceman's Log" and Bryan Maher's articles, not to mention the other interesting articles and projects featured, and John Hill's "Vintage Radio" . By the way, in part 21 of "The Evolution of Electric Railways", the caption for the photo of the 86 class electric loco mentions "... a full load of fuel and ballast". I am not sure what this means but suspect the full load may be sand which is dropped under the driving wheels to maintain traction when required. Another reader did write in about this some time ago but I cannot remember when or the exact outcome. Oh, well! And while I am on the subject, in part 6, the caption for the photo of the parcel van on page 74 mentions "its 537kW motor". I always thought that they were fitted with two 269kW motors, as were the power cars of the normal 1924-28 suburban electric trains. I could be wrong of course! The parcel vans do not seem to get that much work around the Sydney network any more. P. Maljevac, Sydney, NSW. We're glad you 're all steamed up about the project - it does work well. As far as the 86 class loco is concerned, the caption was a mistake. And you are probably right about the electric parcel vans having two 269kW motors. Thanks from competition winner As the fortunate winner of the Bose Lifestyle Sound System in the recent competition sponsored by SILICON CHIP and Bose Australia, I would like to extend my thanks to you for giving me the opportunity to own sound equipment of such high quality. I would also like to mention the high quality of assistance offered to me by the management and staff of Charlestown Hifi and Bose Australia. S. McDonald, Warners Bay, NSW. Compact unit, about twice as lond as a standard IEC socket. Not just a cheap filter that has a few capacitors: This unit includes tow 1.7mH inductors and three capacitors in a shielded metal can. It is 240V/3A rating which means that it can supply up to 720 watt loads. With every filter we will include a 140 joule varistor as a FREE BONUS! That is about 1/3 the price that you would expect to pay! What would you expect to pay for this LIMITED STOCK ITEM?? ONLY $9.90ea This is for the mains filter and the varistor. 10+ $8.90 (Accessories not included). You can easily make this unit into a complete mains filter as shown in the photo below: ~ ~ BATTERY BARGAIN • ~«)}£¾'< " •.... ~c ff .~ ,, '1 ~ $29.90 including P+P (anywhere in Aust.). Additional BONUS. FREE P+P for any other products ordered at the same time if you purchase a battery at this price. DUAL ELEMENT PYROELECTRIC SENSOR Not only 1/2 price of inferior single elements units, this unit comes with a fresnel lens and CCT. ONLY $9.90 10+ $9.00ea OATLEY ELECTRONICS PO BOX 89, OATLEY, NSW 2223 Telephone: (02) 579 4985 Fax No: (02) 570 791 0 Certified p&p: $5 inAust. NZ (Airmail):$1 O Fax orders are accepted with credit card a ments. ] UNE 1991 5 Electric vehicle transnrlssion options Just as with motors, there are many options when it comes to selecting the transmission systems for electric vehicles. There ca.n be all sorts of belt and gear drive systems combined with one, two or more motors. By GERRY NOLAN We've come to the point in our story where we have to consider converting all of that perfectly controlled power from the electric motor(s) to motion of our electric vehicle. This is an area of vehicle development that lends itself to the greatest variety of innovations and choices. We have to consider whether to change gear or not, whether to use manual or automatic gears, and whether to use a geared transmission, direct drive, chain drive, geared belt drive or continuously variable drive . The number and type of wheels and tyres are also important considerations: three or four wheels, front or rear drive, rolling friction, tyre profiles and pressures. A great deal of time and money can be saved by mod- elling the drive train, taking into consideration all the variable parameters such as: vehicle design and structure, batteries, driveability, suspension and steering, weight, materials, and driver and passenger safety. Generally speaking, the transmission parameters for an EV are the same as for a conventional ICE vehicle with one major difference. If a petrol or diesel engine is used, you have no choice but to use a gear-changing mechanism of some kind. As we found out in the third article in this series (March 1991), this need not be the case with EVs as torque and speed can be controlled electronically. The type of transmission used will depend on the usual vehicle weight, size and cost parameters. Neverthe- Table 1: Drive Cycle Comparisons Cycle CVS HWY SAE J227 TAXI DELIVERY SAE J227a-D SAE J227a-C 6 SILICON CHIP Duration sec. 1372 865 150 1100 2500 122 80 Speed Max. Avg. km/h km/h Power Max. Avg. kW kW 91.2 96.4 72.4 53.9 52.5 72.4 48.3 37.0 31.0 26.8 32.4 24.0 29.7 20.1 31.4 77.7 38.8 11 .1 5.6 45.0 23.4 5.6 13.8 6.5 2.5 1.1 6.9 5.2 less, the purpose for which the vehicle is designed will be the major consideration and one of the most important aspects of this is the driving cycle. Driving cycles Component and vehicular energy efficiencies are obtained by adding up the energy use as a vehicle is driven through a particular series of driving operations known as a driving cycle. Typical examples are: city, rural, commuter, delivery, taxi and so on, all of which have their own pattern of idle, acceleration, cruise speed, coast and deceleration, and all of which will have a bearing on the type of transmission used. Some standardisation of driving cycles was obviously desirable from the start so that meaningful vehicle comparisons could be made. Several standards are in use today, the most common in the United States being the Federal Urban Driving Cycle, usually referred to as the CVS Cycle (constant volume sampling of emissions), and the Federal Urban Highway Cycle (HWY). Europe uses a composite of these two in its ECE Cycle. The first standard driving cycle for EVs was the SAE J227 (1972) EV Cycle, which was designed to give approximately the same road-load energy per kilometre as the CVS Cycle but with lower peak road-load power. Because it soon became apparent that many EVs already in existence couldn't achieve the road-load power levels required in the SAE J227 Cycle, it was re-issued as a set of four simplified cycles, designated SAE J227a -A, - B, - C and - D. The various driving cycles are summarised in Table 1. Changing gears It might seem that, because of the degree of motor control already mentioned, it would be unnecessary to motor speeds. And, as well as being one of the most reliable devices used in vehicle drivetrains today, manual transmissions generally have higher energy efficiencies than electronic controllers. In essence, what we are saying is that the motor required to perform a specific task will be smaller in size, weight and cost if gear changing is used than the motor required if no gear changing is used. The advantages of selectable gear ratios are illustrated in the graphs of Fig.I. Tractive Effort (N) 7000 6000 /1st 5000 4000 3000 2000 Manual or automatic 1000 0 0 20 40 60 80 Speed (km/h) Fig.I: this graph shows the performance through the gears of the Finnish ELCAT electric vehicle project. use gears. However, if high loads are expected, either because of steep terrain or heavy payloads, gears may be advisable to reduce excessive motor currents which can cause overheating. We should al('>o bear in mind that the power semiconductors used in the controllers must be selected on the basis of maximum armature current - even if it is only expected for a few moments of the driving cycle. This means that the maximum size, cost and weight of semiconductors must be carried at all times for a few moments of use. The same applies to battery requirements, although this may be minimised by controller design, but only with the aforementioned penalty, so we're back to where we started. In fact, reductions in the size and weight of the motor and its controller are the main advantages to be gained from using gears, provided of course the geartrain itself does riot outweigh the advantage gained. Reducing motor size by including a gearbox will nearly always result in an economic gain, simply because motors are generally constructed from costly materials, while transmissions are among the lowest cost devices around (on a $/kg basis) . With a transmission, the EV drivetrain can be operated at nearly optimum efficiency over the whole driving cycle, as the efficiency of the transmission may vary little with speed and torque. Using a gear-changing mechanism also greatly enhances regenerative braking over a much wider range of Assuming that the above discussion has convinced you that a gear changing transmission is the way to go, would you choose manual or automatic? As most readers will know, automatic transmissions are not as efficient as manual transmissions, mainly because of losses in the torque converter. This problem has been overcome in the Nissan Miera EV-2 prototype by the use of a one-way clutch for Ist gear and an electromagnetic clutch, which acts as a 'binary transmitter', sending either all or no power to the drivetrain, for second gear. Fig.2 illustrates this particular transmission scheme. At least one electric vehicle in Australia, a Suzuki locally built by Les Puklowski at his Huntington Electric Vehicle factory for a specific client, uses an automatic transmission. According to Les , the vehicle is very smooth to drive. On the other hand, The Fiat Panda Elettra uses a 4-speed manual gearbox and has automatic regenerative braking. JUNE 1991 7 2ndGEAR ELECTROMAGNETIC CLUTCH lstGEAR other types of transmissions. The drive for the Solar Star II is from the motor via a geared belt to a jack-shaft and lightweight differential with a 1:1 ratio, giving an overall ratio of 8:1 from motor to drive axles. In-wheel electric motors Fig.2: the 2-speed electric automatic transmission scheme used in the Nissan Miera EV-2. the Finnish EV-project, called ELCAT, a lightweight delivery van which has been converted to electric drive, has a 5-speed manual gearbox. Its performance through the gears is shown in Fig.1. Several vans, namely the Peugeot JS/Citroen C25 van and the Fiat 900 E/E2 electric van use manual gearboxes. The Fiat Panda Elettra (pictured) uses a 4-speed manual gearbox and has automatic regenerative braking. Les Puklowski, who has built over 50 electric vehicles, the latest being the Solar Star II, is firmly convinced that an 80V-120V DC motor with manual transmission is the best way to go for small EVs. Table 2 gives estimated weight and energy efficiencies for 2-speed, manual EV transmissions. Continuously variable transmissions Ideally, these maximise motor/controller/battery efficiency over all the vehicle speed and torque requirements. They improve acceleration and give automatic control comparable to all-electronic motor control, as well as automatic down-shifting during regenerative braking. 8 SILICON CHIP A great deal of work has been done on CVTs, particularly in America, but most types have proven to be too costly, noisy or inefficient for EV applications. Nevertheless, one of the most-likelyto-succeed CVTs for electric vehicles is the belt-type, a schematic of which is illustrated in Fig.3. Even as far back as 1982, the Van Doorne CVT, which uses a metal belt and variable-ratio conical pulleys, achieved a zero drivetrain loss at vehicle standstill - such as waiting for a stop light. This can result in a 10% fuel saving over the CVS cycle, a very desirable objective in any power train. Final drives Twenty-eight of the 33 solar electric vehicles which started in the 1990 World Solar Challenge, including the winning Spirit of Biel, used chain drives and five used toothed belt drives. Four of the chain-drive vehicles also used manual gears . If a 'solid' transmission such as mechanical gearing and a tailshaft is used, some type of differential is obviously required. The energy efficiencies of typical differentials in conventional cars are in the range of 92-95 % , which compares very favourably with Apart from the obvious disadvantages of high unsprung weight and running an electric motor in a hostile environment of heat, dust, mud, slush and vibration, the idea of building electric drive motors directly into the wheels of a vehicle has some merit. John Hill, currently national secretary of the Australian Electric Vehicle Association, built and successfully raced his Dart electric car in 1988 with an in-wheel motor of his own design and construction. More recently, a Japanese consortium built an electric vehicle with a motor in each of its four wheels and achieved a top speed of 110 km/h and a range of 240 kilometres. Mr S. Monji, of the Kyushu Electric Power Co. Inc, has also produced both 2-wheeler and 3-wheeler scooters using in-wheel motors. He claims considerable advantages in efficiency, as well as weight savings and more room for the batteries. At the other end of the scale is the CNR-IVECO Fiat dualmode, articulated bus with integrated wheel motors. These are powered by an on-trolley bus line system integrated with a diesel generator unit and a high power nickel-cadmium battery. How many wheels? Because the two main energy losses in an electric vehicle are caused by tyre rolling resistance (or friction) and wind resistance, any way in which these two factors can be reduced must be considered. For a vehicle in slow moving city traffic, tyre rolling resistance is the greatest loss. Readers who have seen solar electric vehicles or pictures of them will have noticed the prevalence of skinny wheels, often with streamlining discs or fairings, and bicycle tyres. This type of running gear keeps the rolling resistance to a minimum and is suitable for lightweight vehicles, but is fragile and susceptible to damage. More practical vehicles need to compromise with tyres that have greater load bearing capability. More research is being done with very low Table 2: estimated weights and energy efficiencies for twospeed manual EV transmissions Electric motor max. rpm Weight kg 6000 9000 12000 19.0 17.3 16.8 profile, high pressure tyres. For example, the General Motors Impact uses specially developed Goodyear G-22 tyres that operate at air pressures of 450kPa (65psi), or about twice normal tyre pressure. This, coupled with a narrower than usual, rib-like tread, which has small block elements and numerous 'sipes' (small slits in the tread) to improve grip, gives a rolling resistance that's about 55% less than conventional tyres . When deciding on the number of wheels, wheel profile and tyres, the preferences of the buying public will have to be taken into consideration. Rightly or wrongly, we more readily accept four wheels and wider tyres for aesthetic as well as perceived safety reasons. A good example of this is the Solar Star II, which looks instantly acceptable as a road vehicle . Front or rear drive? With EVs, the choice between front or rear-wheel drive is wide open. The field covers everything from directdrive in-wheel motors to electric motors driving the rear wheels by chains or geared belts and a conventional ICE engine driving the front wheels through a gearbox and differential, or vice versa. Efficiency % 97 96 .8 96.4 Table 3: EPA and optimum gear-change schedules for a four-speed transmission EPA Gear change km/h 1-2 2-3 3-4 Placing the batteries in the rear of the vehicle and using the electric motors to drive the front wheels, by one of the methods we've discussed above, would make for a , well balanced vehicle from a weight distribution point of view but then, so would mounting the batteries in the front as BMW has done on an experimental vehicle - and driving the rear wheels electrically. The choice will be determined by many factors and can be arrived at by experimentation or by the cheaper method of computer modelling. Computer modelling Making a computer model of your EV, taking into consideration all the variable parameters, can save a lot of time and avoid design problems. One such problem is weight compounding, where an increase in battery capacity to increase range (say), results in an increase in battery weight, which requires a stronger, heavier frame, which needs a larger motor to attain the same performance, which needs more battery capacity to reach the same range, and so on. As with any other system, the ap proach to the modelling system will depend a great deal on the desired end results. 24.0 40.2 64.4 Optimum km/h 15.6 30.0 38.6 Some definitions will help to clarify this: • Performance is used to describe vehicle acceleration - usually in the wide-open-throttle (WOT) or maximum power condition; • Fuel economy refers to the distance travelled per unit of energy and is the reciprocal of fuel consumption in kilowatt hours per kilometre; • Vehicle range is the distance a vehicle can travel per charge of input energy; all of which are measured for a specific driving cycle; • Inertia weight or test weight refers to the vehicle weight used in testing any of these parameters; Energy efficiency is the ratio of the road-load energy to input energy during a specific driving cycle. Whether we are modelling for range and performance predictions, dynamic or economic analysis, vehicle optimisation or component or vehicle design or size, it is most important to consider the following elements. Drive cycle This will almost certainly have been in mind from the very beginning. If an electric vehicle is being designed to win competitions, the drive cycle, and consequently the design, is obviously going to be completely different from Below: the Australian-designed "Solar Star II". ' t<:'.'\.' • <- , ,. * I COMPUTER PRINTERS/ JU NE 1991 9 Low-ratio used is equal to a reference charge. Gauges are becoming available that indicate the amount of charge remaining. One type indicates the· discharge in ampere-hours as a minus value and adds back to zero as the battery is recharged. A point to remember is that the available capacity usually decreases as the rate of discharge increases. Meters that indicate the vehicle range in kilometres at the current rate of energy use are being developed and will no doubt be readily available as soon as the demand justifies it. The future ofEVs in Australia High ratio Fig.3: basic scheme for a belt-type constant velocity transmission (CVT). A constant velocity transmission is just one of the many transmission options available to electric vehicle designers. that of an EV intended as a commuter vehicle. Weight considerations These will include structural and frame factors, which are in turn determined by the battery, its weight and location, heat transfer provisions, charging gas ventilation, crashworthiness, and battery maintenance requirements. Other factors will be the size and weight of the auxiliary power systems, driveability (including suspension and steering), weight compounding, materials selection and driver and passenger safety. The body design will need optimising for minimum drag, maximum strength to weight ratio, and stability. Th ese factors determine the materials us ed, taking into acco unt their strength, weight and shaping potential, and their availability. Drivetrain control strategy The drivetrain contro l strategy is arrived at after considering the type of motor and controller, and the points rais ed in the above discussion; ie, the number and type of wheels and tyres; the type of transmission; gearbox or 10 SILICON CIIIP electronic motor control or a combination of both; and how the regenerative braking is to be arranged (automatic on throttle release, brake pedal activated or a combination of both). Gear-changing strategy This is the fancy name given to the predetermined set of speeds at which you change gear. The most commonly used is the EPA schedule, which is used by the US Department of Energy for emissions and fuel economy testing of US passenger cars. However, as Table 3 indicates, the EPA schedule speeds are quite different from the optimum speeds for a 4-speed gearbox. The main criterion for selecting the optimum gear change speeds is that sufficient motor torque is available at the change speeds. Battery control strategy The most realistic cut-off point for a battery is that at which the battery can no longer meet the road-load . power required by the drive cycle. In other words, 'the battery's flat , Mum'. More convenient methods of indicating this are a specified minimum terminal voltage or when the charge After researching this series of articles, I have learnt that the technology to make practical, economical electric vehicles is available right now. General Motors are ready to go into production with their Impact and literally dozens of other major vehicle manufacturers around the world have working prototypes. Electric vehicles have been delivering milk in England and mail in America for many years. What's stopping the introduction of electric vehicles for passenger transport then? This can be summed up in one word: demand - or the lack of it. Demand will increase when EV prices drop, either through manufacturing economies or tax incentives, so that the cost of buying and running an EV is less than the cost of buying and running an equivalent ICE vehicle. Don't hold your breath waiting for tax incentives. The Australian Electric Vehicle Association wrote to the Federal Government in July 1989 asking it to consider removing sales tax from electric vehicles (for 5 years, say) to spur the development of such vehicles. The reply (dated 23 January, 1991) stated that the Government was "reluctant to add to the number of sales tax concessions". In short, the answer was 'No'. The large manufacturers are already well down the track towards producing acceptable EVs from both aesthetic and economic points of view. 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YOUR EIGHT SPECIALTY STORES IN ONE 81135/ PB PART '1 Satellites are now used to distribute a raft of TV signals into & around Australia. This series discusses the basics of satellite TV reception, looks at the signals available, and shows you how to tune into these signals using a low-cost commercial ground station. By GARRY CRATT ' The ;;./;~I{) i~l~1I8:~~i~;); This 1.8-metre dish is sited in a Sydney suburban backyard & receives good TV pictures from Aussat 1. The programming carried includes American news feeds (eg, CNN - Cable Network News) plus various interstation feeds between local stations. Note the low-noise block (LNB) at the focal point of the dish. 14 SILI CON CIIII' first man-made satellite launched into orbit was the Russian" Sputnik 1" in August, 195 7. It circled the Earth in a low polar orbit that required constant tracking adjustment to receive the Morse code signal it transmitted. Later, in December 1958, the US Airforce launched a satellite named "Score" which transmitted a pre-recorded message from the President. It too was launched into a polar orbit. The world 's first geostationary (or geosynchronous) satellite was designed and built by the Hughes Aircraft Corporation in 1963. It was called "Syncom" and had the capacity to relay either a single TV channel or 50 separate telephone conversations from its orbit high above the equator be- --- axis at a fixed rate. This spin stabilisation technique was subsequently used by most other satellites. Subsequent Intelsat satellites launched in 1966 and 1967 also used omni-directional '\ antennas but were placed \ I in positions around the \ I globe as shown in Fig.1. \ I This enabled the \ I Intelsats to illuminate I I I more than 40% of the I Earth. This technique , · I I I now known as a global \ \ I beam, allowed Intelsat to I \ extend communications I \ services to locations both / '\ north and south of the equa/ tor. / / In 1965, the USSR launched a / / domestic satellite communications / ...... system called Molniya (Russian for lightning). It connected isolated villages and towns throughout the Soviet Union with radio and TV broadFig.1: the Intelsat series of satellites launched in 1966 & 1967 were placed in casts originating from Moscow. But geostationary orbit at intervals around the globe so that they covered more than instead of using a geostationary orbit, 40% of the Earth's surface. They employed large omni-directional antennas & carried 240 voice circuits & one TV signal. the Russians deployed several satellites in an elliptical orbit around the lite as it passes overhead (ie, the sateltween Africa and South America. This Earth. As a result, ground stations lite is fixed with respect to the Earth). position allowed it to relay the first had to constantly track the satellite as it passed overhead. real live TV transmissions between If we were to populate the geostationary orbit with satellites spaced North America and Europe. The Molniya system is still used By 1965, the scientific community at 2° intervals, we would only be able today, distributing TV and FM radio programs from Moscow to remote had realised that TV sign als could be to accommodate 180 satellites. This is the limit of the geostationary syscommunities in Russian-influenced easily distributed over vast distances tem. To date, there are 89 satellites in regions of the northern hemisphere. by using satellites in geostationary orbit as relay stations. A geostationary geostationary orbit and orbital "slots" Global coverage are allocated by the ITU (International satellite is one which remains above Telecommunications Union), based on the same spot on the Earth as it orbits. By the late 1960s, Intelsat had deThis means that the time taken for a the needs of member countries. The vised a system where spin stabilised 2° separation limit, by the way, is the geostationary satellite to complete one satellites were given orbital assignsmallest that can be used by small orbit in space is the same as the time ments over the Atlantic, Pacific and Earth terminals on a non-interference taken for the Earth to rotate once on Indian Oceans to cover the entire basis. its axis. globe. By this tim e, the telephone caThe distance above the Earth that a pacity had been increased to 1500 Intelsat 1 satellite must reach to remain in simultaneous voice circuits and one In 1966, the International Telecom- TV circuit. In addition, those satelgeostationary orbit is about 36 ,800 munication Satellite Organisation kilometres (22,280 miles). This aplites carried directional antennas so plies to all geostationary satellites. (Intelsat) launched Intelsat 1 (also that the full available power was radi known as Early Bird) into a geoLogically, the higher an object is , the ated towards Earth. longer it takes to orbit the Earth; and stationary orbit over the Atlantic Subsequent Intelsat satellites dethe lower the orbit, the shorter the Ocean. It had the capacity to transmit veloped in the 1970s carried steerable 240 voice circuits or a single TV sigtime. This is why satellites used for spot beam antennas which were able navigation purposes are located in a nal but, partly because it employed to concentrate transmitted energy into an omni-directional antenna, a large low polar orbit where they can orbit powerful beams on desired areas of proportion of the available energy was the Earth every 90 minutes. the globe. Also, by the late 1970s, the radiated in directions where it could A geostationary orbit has two major capacity of the Intelsat satellites had not be used . advantages over a polar orbit: (1) the been improved to a level whereby distance between the satellite and the In order to keep the satellite an3,750 telephone circu its and two TV receiving station is constant; and (2) tenna oriented in the correct plane for channels co uld be carried simultanetransmitting towards Earth, the cylinthere is no need to continuously move ously. Of course, these signals were drical body ofintelsat was spun on its the ground antenna to track the sate!designed for reception by large Earth '' " --- "' ''', ---- - - ]UNE 1991 15 stations having a parabolic dish antenna measuring 10-20 metres in diameter. Home satellite TV It wasn't until late 1975 that a British experimenter, Steve Birkill, intercepted satellite TV transmissions using a small Earth station. The signals came from ATS-6, a satellite loaned to India by NASA and located in a temporary orbital slot over the Indian Ocean. It was all part of an experiment to show how satellite technology could deliver educational television to small communities scattered · throughout India. Using a 1.5-metre antenna made from wire mesh, Birkill was able to receive transmissions from the satellite in his back yard in Britain, thousands of kilometres away from the centre of ATS-6's footprint. It is largely due to his pioneering efforts that private individuals realised that the reception of satellite TV was •within their means. But Birkill wasn't alone in his efforts . Several innovative American enthusiasts, including Bob Cooper and Taylor Howard, were also busy developing reception techniques based on surplus military equipment. Their efforts were directed at amateur radio operators and experimenters alike. By 1979, popular American electronics magazines carried designs for do-it-yours elf Earth stations, primitive by today's standards, but neverthel ess capable of receiving satellite TV signals. Because of the large US population , there was some commercial motivation for networks in the USA to utilise satellite technology to deliver TV programming and, later, exclusive pay-TV services. In Australia, however, the Intelsat series of satellites was mainly used to provide a link to the Northern Hemisphere. It was not until 1980 that Intelsat IV was used by the ABC to relay programming from Sydney to outback locations in Western Australia. These signals were received by dedicated large Earth stations and re-transmitted terrestrially using the PAL system. In addition, as Australian TV networks developed, they increasingly relied on satellites to relay US news programs. As a result, several networks leased transponders on a series of Intelsat satellites which broadcast TV signals into Australia. These signals were also designed for reception by large Earth stations and sometimes used scrambling techniques to ensure privacy. By 1980, a few satellite television enthusiasts in Australia had developed techniques which allowed them to monitor these TV transmissions. In addition, it also became possible to receive a later generation of Russian Sqtellites named Gorizont, as well as domestic satellites serving Indonesia (Pala pa). And as technology improved, the cost of the receiving equipment dropped, thus making access increasingly easier. Receiving systems Generally speaking, there are two frequency bands used for satellite television reception. The oldest system operates in the "C band" which covers from 3.8-4.ZGHz. This system re- Fig.2: this map shows the signal footprint from a 12W transponder on one of the Aussat satellites. The contours indicate lines of equal signal strength. Note how the signal level decreases as the distance from the beam centre (or boresight) increases. -15 ·20 I I I L ____ i__, ·25 I I ·30 .35 ·40 115 16 120 125 SILICON CHIP 130 135 140 145 150 155 ANGLE OF ELEVATIONPERPENDICULAR TO EARTH 'S SURFACE LINE PARALLEL TO EARTH 'S SURFACE (a) Fig.3(a): the single pole fixed mount technique is the easiest way of mounting a dish if only one satellite is to be viewed. The elevation is adjusted using a turnbuckle or threaded rod arrangement. ANGLE OF ELEVATIONPIVOT MANUAL _- Em~11g~ - MANUAL AZIMUTH ADJUSTMENT (b) Fig.3(b): if more than one satellite is to be viewed, the alternative El/Az (elevation/azimuth) mount can be used. The arrangement shown here allows manual adjustment of both elevation & azimuth. quires a large dish for good reception - about 3 to 6 metres, depending on the satellite signal or "footprint" level. The "footprint" is simply the illumination pattern from the satellite as it falls on the Earth and this is often depicted as a map with contours showing the signal strengths. But no matter what type of beam pattern is transmitted by the satellite, the footprint provides the strongest signal in the centre of the pattern. As the distance from the beam centre (or "boresight" as it is often called) increases , the signal level progressively decreases. When planning a ground station, the local signal strength is obviously an essential piece of information. This information is available in various specialist publications which show the orbital assignments and footprint coverage for all international satellites. A satellite footprint map indicates the performance that satellite engineers expect at a particular. In some cases the level may be higher than indicated but more often it is lower, especially as the output power of the satellite drops with age. The contours of a footprint map are expressed in dBW (decibels referenced to one watt power). Fig.2 shows the footprint over Australia from a 12W transponder on one of the Aussat satellites. To obtain the boresight EIRP (effective isotropic radiated power) level, the gain of the transmitting antenna must first be added to the power level of the spacecraft transmitter. It's then a matter of subtracting any losses caused by the feedline and multicouplers on board the satellite, and the path loss which is of the order of 200dB or so. Because of these losses, the signal intensity on the Earth is often below the level of ground noise. This is why particular attention must be paid to dish accuracy and size , as these two parameters play a critical part in determining the performance of an Earth station. For example, a 6-metre dish typically has a gain of about 45dB as opposed to about 40dB for a 3-metre dish. Obviously, a 6-metre dish installation would be impractical in a typical backyard. However, a 3-metre dish, using suitable electronics to provide reasonable results, could be accommodated. System components This close-up view shows the general arrangement used for the single pole fixed mount technique. Note the long threaded rod which is used for making azimuth adjustments. The dish is clamped to the top of the pole using U-bolts. A satellite system comprises a dish, feedhorn , LNB (low noise block), receiver, video monitor and audio amplifier. The dish, the most obvious component of a satellite system, is normally parabolic in shape and made from steel, aluminium or fibreglass sheeting impregnated with a reflective coating. Some manufacturers use mesh instead of sheeting, to achieve a reduction in wind resistance. The dish must also be coated with some kind of weatherproofing material to prevent corrosion and pitting of the reflective surface. The most important parameter of the dish is its gain, and this is dependent on the accuracy of the parabolic surface of the dish. Any imperfections or deviations of 2mm or more from a perfectly parabolic surface can mean a significant drop in efficiency. Smaller dishes (up to 2 metres in diameter) may be produced in one piece, either spun from aluminium or, if fibreglass, made in a mould. However, one-piece construction is impractical for the larger dish sizes which are often made up of a number of identical "petals". This makes transportation to the site far easier. There are several methods of mounting a satellite dish, the method selected depending on the us er's needs . If the obj ective is to view one satellite only, then a simple single pole "fixed mount" will be acceptable (Fig.3a). The dish is fix ed on top of a pole and the elevation (above the horizontal plane) adjusted using a turnbuckl e or length of threaded rod. Somet imes a car jack can be used under the front of the dish as the elevation mechanism. Th e pole is cement ed into th e ground, so that it is strong enough to support the dish and also to prevent any movement in strong winds. This is important, as any movement of th e dish in either the horizontal or vertical planes by more than 25cm can caus e degradation of the picture. For users interested in observing more than one satellite, the "El/ Az" mount is suitable (Fig.3b). This mounting metliod allows th e dish to be moved from one satellite to another, by readjusting the elevatio n and the azimuth. Although this can be tedious, the El/Az mount is simpl er to construct than th e "polar" mount, which allows geosynchronous satellites to be tracked with only azimuth ad justment to the dish. ]UNE199 1 17 F • F=D'/16C Fig.4: the focal point of the dish can be calculated by measuring its depth (C) & its diameter (D) & plugging these values into the formula F = D2/16C. In operation, the dish must be positioned so that it has a clear view of the satellite. The view must not be blocked by trees, buildings or any other objects, as this will eliminate all signals. In addition, the bottom front lip of the dish should ideally be mounted one metre or so above gro und level. to minimise ground noise. Different dishes The purpose of the dish is twofold: (1) to collect the maximum available signal; and (2) to focus this signal on the feedhorn. It is therefore important to appreciate the different types uf dishes. A parabolic dish can have either a shallow or deep parabolic curve. This in turn will determine the focal point, which is important for correct placement of the feed horn components. Every dish has a design "focal length to diameter" ratio. This simply means that the amount of curvature built into the dish establishes a relationship between the diameter and the distance from the back of the dish to the focal point. This ratio can easi ly be calculated by measuring th e diameter across the front of th e dish and th e distance from the back of the dish to the point of intersection across the front of th e dish. In practice, this can be easi ly done using a piece of string stretched across 18 SILICON CHIP the front of the dish, and a rigid tap e measure. Fig.4 shows the formula for calculating the focal point. Once this has been calculated, the F I D ratio can be derived. One confusing aspect of all this is that a dish having an F ID ratio of 0.5 is actually shallower than one having an F/D of 0.25 , although the magnitude of the ratio might seem to indicate otherwise. The advantage of using a deep dish is that it produces better side lobe rejection, thereby reducing the effects of unwanted terrestrial signals. This is often quite an advantage for C-band users, as there are often terrestrial microwave links operating in the same band that can cause interference. There are still many Telecom links operating around Australia on this band, each operating at a signal level hundreds of times more powerful than the satellite signal. It is important that the feedhorn illuminates the entire dish, not just part of it, to achieve maximum efficiency. Feedhorns are manufactured to suit dishes having a particular F/D ratio , so the choice of feedhorn is important. There are several different feedhorn arrangements. The most simple and widely used is th e "prime focus " feed, where th e feedhorn is placed at the focal point of the dish . Whilst this is a simple arrangement, alignment is critical. Fig.Sa shows the details. Another type of feedhorn arrangement is the "cassegrain" feed (Fig.Sb) . This system uses two reflectors - the dish itself and a smaller second reflector at the focal point. This second reflector has Lhe shape of a hyperbola, and reflects the signals through a hole in the centre of the dish to the LNB. This system has a higher gain/noise ratio and is superior in performance to the prime focus system, but only on large dishes where the dish size corn- pensates for the aperture blockage caused by the sub-reflector. Just as a terrestrial TV antenna must be connected to a receiver, the feedhorn of a satellite system must be connected to the antenna. The dish is really only a reflector, and the energy from the feedhorn must be connected to the antenna which is actually a "probe" mounted in the mouth of the COAXIAL CABLE TO RECEIVER (a) SIGN AL FROM / / SATELLITE / (b) Fig.5: the two different feedhorn arrangements. The "prime focus" feed shown at (a) uses a feedhorn at the focal point of the dish while the "cassegrain" feed shown at (b) uses a second small reflector to reflect the signal through a hole in the centre of the dish to the LNB. FROM LOW NOISE BLOCK AT ANTENNA 1450-950MHz 70MHz IF TUN ING VIDEO PROCESSING VIDEO OUTPU T AUDIO PROCESSING AUDIO OUTPU T DEMODULATOR AFC LO CAL OSCILLATOR Fig.6: block diagram of a typical satellite receiver. Frequency conversion from either 4GHz or 12GHz to the first IF (1450-960MHz) is carried out in the LNB & then applied to the receiver for conversion to a second IF at 70MHz. I \ -10 RECEIVER THRESHOLD POINT ii, 40 ~ -20 ~ >:::, ; ~ -30 > ~ ffi c:, ~ ,!,_ '-' w cc :::, 30 1 - - - - ->-- t c c - - - - - - - - - - - - - - fuc:, > cc -40 ,........ 20 ~~~-~~~-~~~-~~~-~~~ 4 -60 20 ~ ,_,. . .~- -50 30 40 50 60 70 80 90 100 110 120 5 6 1 .. POOR FREQUENCY (MHz) Reception techniques These days, frequency conversion from either 4GHz or 12GHz to the first IF (1450-950MHz) is done in the LNB (low noise block converter) which is essentially a low noise amplifier and frequency converter in one package. This converter produces a block of output frequencies 500MHz wide, which is then fed via a coaxial cable to the receiver. The receiver contains a second frequency converter and a local oscillator which is either manually tuned or stepped using a synthesised PLL (phase lock loop) circuit. This provides a second IF at 70MHz which is 8 , ,. FAIR 9 1 .. 10 11 GOO□ 14 15 16 EXGELLENT VIDEO RECEPTION QUALITY Fig.7: typical 70MHz SAW filter response. The steep skirts ensure that signals interfering with the 70MHz IF are substantially rejected. LNB. To make this connection we use a waveguide, which is far more efficient than coaxial cable because it uses air as the dielectric. The physical dimensions of the waveguide determine the impedance. Because the probe is fixed when the LNB is manufactured, it cannot be moved to allow reception of different polarity signals. Nor is it convenient for the user to have to rotate the LNB every time a transponder having a different polarity is selected. To counter this problem, various mechanical rotation devices have been used over the years with varying degrees of success. One "no moving parts" solution is to use a dual polarisation feed. This system uses the principle of Faraday rotation where an axial magnetic field is applied to a waveguide containing ferrite material. A current carrying coil is wound around the ferrite and the resulting magnetic field changes the polarisation of the incoming signal. 7 Fig.8: the video quality drops markedly when the relationship between the C/N (carrier to noise) & SIN (signal to noise) ratios becomes non linear. then amplified, filtered and detected using a balanced demodulator to provide a baseband output. This baseband output contains all the video and sound subcarrier information. After further filtering to remove certain video components from the audio subcarriers, the video is processed using a standard video detector. The audio is demodulated using either a PLL capable of covering 57MHz or a quadrature detector operating at 10.7MHz. This second approach allows the use of standard wideband FM filters but does not allow any flexibility when detecting either very wide or very narrow audio subcarriers. Fig.6 shows the block diagram of a typical satellite receiver. To maximise satellite use, a number of transponders or satellite channels are allocated within the downlink passband. These may be either full or half transponders, having a bandwidth or either 36MHz or 18MHz respectively. Because the signals are FM, every effort should be made to obtain a signal level that's sufficient to take the receiver into limiting. This means making the system as efficient as possible. One part of the receiver circuit that plays an important role is the IF filter. The IF filter is normally a SAW (surface acoustic wave) type, with very steep skirts to ensure that interfering signals to the 70MHz IF are rejected by a substantial amount. Fig. 7 shows a typical 70MHz SAW filter response. This is necessary due to the large volume of interfering signals on low band VHF. Obviously, if the banrlwidth of the filter is 36MHz and the bandwidth of the signal being received is 18MHz, a considerable amount of noise will also pass through the filter, degrading the carrier to noise ratio (C/ N ratio) of the receiver. If a filter with a bandwidth of 18MHz is used instead, there will be in improvement of 3dB in the C/N ratio. In practical terms, a half transponder signal can be received using an IF filter having a bandwidth as narrow as 10-lZMHz. The trade off is less intense colour and slightly noisy audio against what can be up to a 6dB improvement in C/N. This is considered very worthwhi le, as most users can tolerate a video signal of less than This view shows the feedhorn & LNB used at the focal point of the 1.8-metre dish. The LNB boosts the signal & provides frequency conversion. JUNE 1991 19 days, noise temperatures of 25°K and 115°K are achievable in C and Kuband LNBs respectively (each costing less than $500). Fig. 9 shows the C/N improvement that can be achieved using an LNB having a lower noise temperature. ...;z ~ > 1.5 g:: 1 0 ~ ~ 0.5 0 ---~--~------'------' 60 50 70 80 90 LNB TEMPERATURE (°K) Fig.9: C/N vs LNB temperature for LNBs with a 120°K (top) & 100°K noise temperature. Note that for a 20°K drop in LNB noise temperature, there is a 0.BdB improvement in carrier to noise (C/N) ratio. broadcast quality, particularly if it is to be viewed on a standard TV set. Even so, it is important to realise that Earth stations must be designed to maximise the incoming signals, whilst keeping external and internal (semiconductor) noise to a minimum. This relationship is expressed as the system carrier to noise ratio, which is calculated by adding the system noise level an d the signal carrier level, and dividing the sum by the noise level alone. Every receiver has a threshold point expressed in dB C/N. As the C/ N falls below threshold, the video becomes increasingly noisy. Fig.8 shows the video reception that can be expected as the receiver drops below threshold. The threshold of the receiver is defined as the point at which the relationship between the carrier to noise ratio (C/N) of the incoming signal and the signal to noise ratio (S /N ) of the resulting video becomes non linear. Above the threshold point, each ldB increase in C/N will cause a corresponding 1 % increase in S/N for the video signal. However, when operating below threshold, a ldB increase in C/N can cause several dB improvement in the video SIN. Polarisation Another important factor to be taken into consideration is the polarisation of th e satellite downlink. In order to achieve some degree of frequency reuse, dual polarity is often used on satellites. As there is sufficient isolation for opposite polarity signals to co-exist (normally 30dB or so), this effectively doubles the number of transponders that can be carried within the satellite bandwidth. While the Australian Ku-band system operated by Aussat uses both horizontal and vertical polarisation , Intelsat IVA and Intelsat V both use circular polarisation. This requires a modification to the feedhorn, to convert from circular to linear polarisation. A righthand circularly polarised signal possesses an electromagnetic fi eld that rotates in a clockwise direc- VERTICAL HORIZONTAL tion while a lefthand circularly polarised signal rotates anticlockwis e. The standard scalar feed designed for linear polarisation can reduce the margin of any Earth station by 2dB unless it is modified. One modification technique is to insert a dielectric plate into the throat of the feedhorn at a 45° angle relative to the orientation of the LNB. probe (Fig.10). When the dielectric insert is positioned on the righthand side of the probe, the feedhorn will intercept right hand circularly polarised (RHCP) signals. Similarly, when the dielectric is placed on the lefthand side of the probe, the feedhorn will intercept lefthand circularly polarised (LHCP) signals. But while this is the simplest and most commonly used method of converting circularly polarised signals to linear polarisation, it is not the most efficient. For C-band reception, where signals are very weak indeed, the use of a "hybrid mode" feed is recommended. This kind of feed uses a series of adjustable screws or, in later models, transitional steps inside the waveguide to perform the polarity RIGHT HAND CIRCULAR LEFT HANO CIRCULA.!1 Fig.10: one technique for converting from circular to linear polarisation is to insert a dielectric plate into the throat of the feedhorn at a 45° angle relative to the orientation of the LNB probe. THIS END FITS INTO SLEEVE ATTACHED TD WAVEGUIDE f SCALAR HORN SLIDES OVER THIS END I Noise temperature As one of the contributing factors to C/N is the internal noise generated by the semiconductor amplifiers in the LNB , by far the most critical parameter when selecting an LNB is its noise temperature. The lower the LNB noise temperature, the higher the performance. In fact, for every 20°K drop in noise temperature, there is a co rresponding 0.6dB improvement in C/N. These 20 SILICON CHIP 1 50mm DIA. COPPER TUBE Fig.11: for C-band reception, the "hybrid mode" feed is used for polarity conversion. This type of feed typically consists of a copper tube fitted with a series of adjustable screws. conversion. Fig.11 shows the details of a screw-type hybrid mode feed. Transmission modes The three major video standards in the world today - PAL, NTSC and SECAM - are also used for international satellite TV transmissions. NTSC is used by the USA and Japan; PAL by the UK, various other European countries , Australia, New Zealand and China; and SECAM by the French and the USSR. Whenever one of these video formats is uplinked to a satellite, the downlink format uses precisely the same standard. This means that it is necessary to use an NTSC monitor to observe NTSC pictures in colour, a PAL monitor to receive PAL pictures in colour, and a SECAM monitor to receive SECAM pictures. Alternatively, for international ~eception, a multi-standard video monitor is ideal as often all three video standards can be carried on the same satellite. In addition to the three world video standards, Australia has also adopted B-MAC as a transmission standard for the Ku-band Aussat system. B-MAC signals use a time multiplex system to create an audio data baseband consisting of a multilevel code that is transmitted during the video signal horizontal blanking period. The maximum data rate of a B-MAC transmission is 1.8Mb/s, while the overall bandwidth of a ·B-MAC signal is just over 6MHz. The B-MAC system is also user addressable and this is a great advantage for pay TV operators who can switch off any clients who fall behind with their payments. Unfortunately, B-MAC is considerably more expensive than PAL, at least as far as the user is concerned. This is considered by many to be the reason Australia's Aussat system has not been as popular as predicted. Audio services Although television reception may often be the prime motive for establishing an Earth station, there are also many single channel per carrier (SCPC) audio services that can be received. Many radio networks transmit SCPC signals by satellite to regional stations around the country. In addition, this system is used on Aussat by the Department of Transport and This US news program was received from Aussat 1 using a 1.8-metre dish linked to a low-cost satellite receiver. In addition to TV signals, the Aussat satellites also carry numerous audio signals from radio networks. Communications to provide communications between aircraft and ground based control zones. The Indonesian Pala pa series of Chand satellites also use the SCPC technique for transmitting FM radio and TV sound signals. SCPC signals are usually located at evenly spaced intervals across the transponder bandwidth. To maximise the number of signals that can be carried, compander circuits are often used to compress the peak deviation level of the audio prior to frequency modulation. This means that expander circuits must be used on the ground to restore the audio signals to their original state. Because an SCPC signal only has a relatively narrow bandwidth, a single transponder can conceivably carry hundred's of different audio signals. In practice, the bandwidth is totally dependent on the amount of deviation. A voice grade SCPC signal may occupy no more than 5kHz, while an audio channel might occupy 60kHz or so of bandwidth. Although modern satellite receivers can usually receive SCPC signals, older receivers cannot. However, this does not preclude the reception of SCPC audio services. A scanner can easily be used for this job by connecting it directly to "tap" off the incom- ing block of frequencies from the LNB. These days, scanners can easily cover the 950-1450MHz band and if fitted with a "search" facility, as most are, can tune SCPC signals with relative ease. Naturally, the IF feed to the scanner must have the DC component removed prior to connection. Another method used to multiplex voice and data signals onto a satellite circuit is FDM (frequency division multiplex). This method is primarily used for voice grade telephony circuits and utilises SSB. In practice, 12 individual SSB signals are multiplexed together to form a composite baseband signal called a "group", each group containing telephone signals spaced 4kHz apart. Several groups can then be multiplexed together to form a "supergroup " which can contain as many as 3600 separate voice channels. To decode FDM transmissions , a scanning receiver can be ~onnected to the baseband output of the satellite receiver. Telephone signals can then be received by tuning from 500kHz to 11MHz or so, using the SSB mode. That's all we have space for this month. Next month, we will discuss the difference between C-band and Ku-band reception, and look at the programming that's available off the satellites. SC JUNE 1991 21 Phone your order to us Toll Free. We guarantee our Jetservice Courier will deliver • to your door faster than any other Australian supplier (including that local supplier just up the road). 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Such as accessing alarm systems, electronic doors, ignition ki llers or just about anything that comes to mind . 2527 Now $45.oo Be quick limited quantltle1. 1000's NOW IN SERVICE IN UNIVERSITIES, COLLEGES, INDUSTRIES AND THE HOME WORK BENCH THROUGHOUT AUSTRALIA. Our superb version incorporates the latest refinements and is now housed in an attractive, tough "ABS" instrument case. This all new compact version has been made possible by use of a high efficiency toroid power transformer. So you win four ways less heat , less weight, greatly enhanced appearance and easier to build. GET AN AMAZING BASS IMPROVEMENT FROM YOUR STEREO SYSTeM. This fantastic adaptor simply " samples" your stereo amp output and pro vides a single channel output to feed a separate sub-woofer amp. Unwanted audio spectrum is removed with the Frequency • Control (c ut-off thresho ld adjustable 60130Hz) . 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It features slim 1u rack mount profile, treble, stereo mono switch and vo lume control. Inputs include phono, tuner, V.C.R. & tape. Virtually all components mount on PCB's, making assembly and construction a breeeze. Altronics kit includes fully professionally punched and printed panels. This novel kit works just like a real poker machine but without the expense of losing money. It has a jackpot and five other wi nning combinations. GREAT AT PARTY'S K Buy Both Kits For $599 and Save 1150 $35.oo 4tlil,O RI£) l.4lllli/lYJl!llflll'I I I ''~ IA'I • .....,- 174 Roe St PERTH WA 6000 Phone (09) 328 2199 PHONE ORDER TOLL FREE 008 999 007 MAIL ORDER Cl - P.O. Box 8350 Perth Stirling St. W.A. 6849 STANDARD DELIVERY & PACKING CHARGE $5.50 to 1Kg, $8 1 Kg-5Kg . AUSTRALIA WIDE - Via. Australia Post allow approx 7 days for delivery. OVERNIGHT JETSERVICE Up to 3Kg is $10.00, 3Kg to 5Kg is $28.00. Overnight Jetservlce Courter for delivery next day Country areas please allow additional 24-48 ~~ K 5015 $229.oo HEAVY HEAVY SERVICE - All orders of 10Kgs or more must travel Exp ress Road Please allow 7 days for delivery. $12.00 to 10Kgs. $15.00 over 10Kgs. INSURANCE - As with virtually every other Australian supplier, we send goods at consignees risk . Should you require comp rehens ive insurance cover against loss or damage please add $1.00 per $100 of order value (minimum cha rge $1). When phone ordering please request " Insurance". TOLL FREE PHONE ORDER - Bankcard , Visa , Mastercard Holders can phone order toll free up to 6pm Eastern Standard Time. Remember with our OvernlghtJetaervlce we deliver next day. ~- AL TRONICS RESELLERS- Chances are therl! is an Altronic Reseller right near yo u - check this list or phone us for details of the nearest dealer. Blue Ribbon Dealers are highlighted with a ■ These dealers generally carry a comprehensive range of Altronic products and kits or we'll order any required item WA COUNTRY ALBANY BP Electronics ■ (098) 412681 Micro Electronics (098) 412077 BUNBURY Micro Electronics (097) 216222 ESPERANCE Esperance Communication ■ (090) 713344 KALGOORLIE Todays Electronics ■ (090) 215212 MANDURAH Micro Electronics (09) 5812206 POAT HEDLAND Ivan Tomek Electronics (O'l1) 732531 ROCKINGHAM TV Joe's (09) 5271806 NT ALICE SPRINGS Farmer Electronics (089) 522388 DARWIN Ventronics (089) 853 622 VIC. 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Audiotrpnics (07-) 8447566 WOODRIDGE David Hall Electronics ■ (07) ~082777 COUNTRY MAROOCHYDORE MALS Electronics ■ (074) 436119 MAAYBOROUGH.J(eller Electronics (07.1) 214559 PIALBA Keller ~1eclronics (071) 283749 ROCKHAMPTON Access Electronics (East St.) (079) 221058 TOWNSVILLE ~4p_erSolex ■,(\)77) 724466SA Force Elecironlcs ■ (08) 2125505 BRIGHTON Force Electronics ■ (08) 3770512 CHAI STIES BEACH Force Electronics ■ (08) 3823366 ENFIELD Force Ele ctron ics ■ (08) 3496340 FINDON Force Electronics ■ (08) 3471188 LONSDALE Force. Electronics ■ (08) 3260901 COUNTRY WHYALLA Eyre Electronics (086) 454·764 TAS. HOBART . George Harvey ■ (002) 342233 LAUNCESTON Georg·e Har~ey ■ (003) 316533 NSW David 'Reid Electronics ■ (02) 2671385 CITY SOUTH Sheridan Electronics (02) 2817727 SMITHFIELD Chantr~nics (02) 6097218 COUNTRY COFF$ HARBOUR Coffs HabourEle9tronics (066) 525684 NEWCASTLE Novocastrlan Eleqt.Supplies (049) 621358 WARNER$ BAYVilec Distributors(0.49) 489405 WiNDSOR ~ &. E Elect. and Communications (045) 775935 WOLLONGONG Newtek Electronics ■ (042) 271620 A corner reflector antenna for UHF TV You can save quite a lot of money by building your own UHF TV antenna and you will generally get better performance into the bargain. This corner reflector antenna covers both UHF TV bands IV and V and should only cost around $30 to $40 to build. By BOB FLYNN & LEO SIMPSON This is not the first UHF antenna we have described. Back in the January 1988 issue of SILICON CHIP. we described a 4-Bay Bowtie Antenna which covered both UHF TV bands. It has proved extremely popular and we believe that many hundreds have been made. So why are we producing a different design and what was wrong with the bowtie approach? Essentially, there is nothing wrong with the bowtie design at all - it works very well although it does require reasonable metalworking skills. No, the real reason for presenting this new design is simply that we wanted to assess a large corner reflector design. We also felt that it should be easier to build than the bowtie design. The corner reflector antenna is not a very common design and is rarely seen in Australia. Essentially, it consists of a single dipole element with a large reflector immediately behind it. The "corner" typically has an angle of 60-90 degrees. Corner reflectors have most of the advantages of bowtie arrays when compared to the most common UHF antenna - the long Yagi. The corner reflector can be designed to cover a wide frequency range, in this case UHF bands IV and V, from 526582MHz and from 603-820MHz. It also has a narrow vertical acceptance angle which is important for reducing interference effects from aircraft (ie, aircraft flutter and ghosting), and it has a good front-to -back ratio. Yet another advantage is that it can be designed for high gain over the full frequency range. The gain of the design presented here is close to 12dB with respect to a simple dipole. The disadvantage of the corner reflector design presented here is that it is relatively large and cumbersome and it does have relatively high wind resistance. It will need a good strong mast to ensure that it does not blow down in high winds. This requirement applies to any large antenna, of course. Solid bowtie This close up view of the antenna shows the triangular dipole elements attached to the balun box. Note the pop rivets attaching the reflector elements to the two booms. Alternatively, you can use stainless steel self-tapping screws. 24 SILICON CHIP In our design, the dipole element is like a large solid bowtie and is made from two triangular sheets of aluminium. The reflector is essentially two large grilles about 65cm wide and 60cm long which are mounted at rightangles to each other. Norie of the parts are difficult to make although you will need some basic metalworking tools. A guillotine would be nice although we did not make use of one when we made the prototype. At the very least, you will need a hacksaw, an electric drill and drill bits, a vise, tape measure or long steel rule, various files, combi- The corner reflector antenna works well on both UHF hand IV and hand V frequencies and gives good reception from line-of-sight transmitters more than 100km distant. At this site in Carlingford (Sydney), good reception of Wollongong stations was obtained. nation square, a centre punch, scriber and a certain amount of patience. A pop rivet gun is also a necessity if you are going to assemble the reflector sections with pop rivets. Fasteners & hardware Based on our own experience, you are wasting your time making an antenna if you don't use the right hardware. The same applies when installing a ready-built antenna too, although it is amazing how often you will see antenna fittings severely corroded after only a year or two of service. Let's talk about fasteners first. Because aluminium is such an active metal, 't he right fasteners must be used otherwise corrosion will be very rapid, especially in seaside areas. Use the wrong types of screws in a seaside area and they will rust out and cause corrosion of the antenna itself in a matter of only a few weeks or even days. (We are especially aware of this corrosion problem since we are situated near Sydney's northern beaches). Therefore, we recommend only four types of fastener for this project: (1) Aluminium pop rivets with alumin- ium mandrels. They may not pull up as tight as those with steel mandrels but steel mandrels rust out; (2) Stainless steel pop rivets; (3) Though often hard to get, aluminium screws are recommended although they are seldom available in self-tapping types and so all screw holes would have to be tapped; and (4) Stainless steel selftapping screws - these are strong, readily available and resist corrosion very well. Now for the junk we don't recommend (unless you are way out in the country where it only rains once every seven years). Avoid using galvanised, bright zinc or cadmium-plated steel screws. These might be OK for roofing but not for aluminium antennas. Also , don 't use brass or mild steel screws. When used in combination with aluminium they corrode extremely rapidly. In fact, forget we even mentioned brass or mild steel screws - we know you're not silly enough to use them! The next item for consideration is the antenna clamps. In the past, muffler clamps have often been used for do-it-yourself antenna installations. The sad fact is that many muffler clamps are not even good enough for mufflers let alone antennas. Try to avoid those with bright zinc or cadmium plating. In seaside areas, the nuts, washers and U-bolts (which are highly stressed) are the first to corrode, followed by the brackets themselves. You have been warned - go for the best antenna hardware you can obtain. We prefer the use of galvanised U-bolts and V-clamps or, if you want to be really fancy, go for ones made of stainless steel. The best place to buy such hardware is often not your local hardware store or automotive accessory outlet but a ships' chandler (ie, boating supplies). At least they know about corrosion problems and are likely to stock suitable hardware, although their prices can be expensive. Making your antenna Making and assembling this antenna is a fairly straightforward process although some steps do require a little patience. You must first obtain all the aluminium and hardware listed in the Bill of Materials and make sure you have access to all the tools listed above. Now let's just explain the various JUN E 1991 25 ✓ (B~ =========~=========...-(Al II II 11 11 II 11 II II I I r--. ---- I _.-(C) II II I _.!1.....1!..._..,J..--,_ _ _ _ _ _ Y<=" T (G) II II '-7 rII 11 II 11 I==== --- /(F) -(F) 11 II lI 11 IQ! Fig.1: this diagram shows the corner reflector antenna in both front and side elevation. All the parts labelled (A) to (F) are detailed in the other diagrams. diagrams you need to refer to. Fig.1 is a diagram showing the completely assembled antenna in front and side elevations. Note that each of the major parts is labelled and is shown in detail on an additional diagram. For example, note the reflector element labelled (A). Twenty-two of these are required and the required dimensions are shown in Fig.2. Also shown in Fig.2 is the reflector boom - shown as (B) in Fig.1. Mast mounting bracket This edge view shows one of the mast mounting brackets which we fabricated from 1.6mm sheet aluminium although they could also be made from angle aluminium. Both pop rivets and screws were used in the prototype because it had to be disassembled on quite a few occasions. 26 SILI CON CHIP Part (C) in Fig.1 is the mast mounting bracket. This is shown in Fig.3 together with the dipole boom and dipole boom bracket. Part (F) is half the dipole which is detailed in Fig.4 together with the balun box drilling diagrams. Fig.5 shows the detail of the dipole boom, balun box and dipole when assembled together. Fig.6 is the circuit of the balun whil e Fig. 7 shows the wiring of the balun PC board. Having obtained all the materials, you can start by cutting all the aluminium elements with a hacksaw. First cut the two reflector booms (see Fig.2) which are made of19mm square tubing. One end of each boom is cut at 45 degrees, so you will need a combination square and a scriber to mark the cut. Centre punch and drill all the holes on both booms. Make sure that all the holes for the reflector elements are positioned precisely as specified, otherwise the reflector elements will be crooked when assembled. The same comment applies to the drilling of the reflector elements themselves. With the drilling of the reflector metalwork complete, you can now pop rivet both reflector grille assemblies. When that is done, put them both aside, well away from your work area and where they are not likely to be snagged as you pass by. Incidentally, a point needs to be made about the pop rivets. Nominally, the aluminium pop rivets you buy over the counter will all be 1/8-inch or the metric equivalent 3.2mm, although some may be labelled as 3mm. By contrast, stainless steel pop rivets are available in 3mm and 3.2mm sizes. Which ever size you buy, make sure that you drill the correct size hole. Do not drill 3.2mm holes for 3mm pop rivets as they will just pull through. "'"' ~1· ·t~ ~ ~ "'"' "' "'"' ~~\ "'"' 4~.. ♦ Dipole elements The dipole is made from two triangular sections of 1.6mm thick aluminium sheet - see Fig.4. Note: you could use thinner material here, say down to 1mm thick but you will still need 1.6mm thick sheeting for the mast brackets (or purchase angle section aluminium). Cutting out the aluminium dipole sections is one of the more tedious steps in making this antenna and this is where having access to a guillotine would be good. Failing that, do it the hard way using a hacksaw and then file all the edges clean and straight. Don't be tempted to use tin snips to cut them out as it is very difficult to avoid buckling the edges. Two holes are required in each dipole half section, drilled at 3.2mm. After doing the dipole sections, drilling the holes in the balun box will be dead easy (see Fig.3 again) although here's a little tip: don't drill at too high a speed otherwise the plastic "'"' ~ 45° -1 ,o I. I s s ~ (A) REFLECTOR 22 REQUIRED MATERIAL:- 3mm x 10mm ALUMINIUM I 19 FRONT SIDE DIMENSIONS IN MILLIMETRES (B) RELECTOR BOOM 2 REQUIRED MATERIAL:· 19mm SQUARE x 1.15mm WALL THICKNESS ALUMINIUM TUBING HOLES:- A AND B: 3.2mm DIA. FOR POP RIVETS OR TO SUIT AVAILABLE STAINLESS STEEL SELF TAPPING SCREWS Fig.2: cutting and drilling details for the reflector booms and elements. Note that one end of each reflector boom is cut at 45 degrees so that it can be correctly clamped in the mast mounting brackets. Make sure you drill the correct size hole for the pop rivets (see text). will tend to melt around the holes. booms. It requires holes to be drilled at the top and sides, as shown in the Next, cut and drill the dipole boom which is made from the same 19mm detail diagram of Fig.3. You have a choice as far as the square tubing as used for the reflector · JUN E 1991 27 -·A ---· --- , 29.5 SIDE 173 TOP (0) DIPOLE BOOM 1 REQUIRED MATERIAL:-19mm SQUARE x 1.15mm WALL THICKNESS ALUMINIUM TUBING 15 25 12 16 33 40 73 40 (E) DIPOLE BOOM TO CONNECTION BOX BRACKET ·2 REQUIRED MATERIAL:· 1.6mm ALUMINIUM (C) ANTENNA TO MAST MOUNTING BRACKET DIMENSIONS IN MILLIMETRES HOLES:· A AND B: 3.2mm DIA. FOR POP RIVETS OR TO SUIT AVAILABLE STAINLESS STEEL SELF TAPPING SCREWS C: TO SUIT AVAILABLE MAST CLAMP U· BOLT 2 REQUIRED MATERIAL:· 1.6mm ALUMINIUM Fig.3: cutting and drilling details for the mast mounting brackets, dipole boom and balun box brackets. Note that the mast mounting brackets could be made from aluminium angle, which would save the need for bending sheet aluminium and give a neater job. mounting brackets are concerned. We made ours from 1.6mm thick aluminium sheet as noted above, but you can save yourself some work by buying a 300mm length of 32 x 32 x 3mm aluminium angle. You will have to modify the drilling dimensions slightly for the mast U-bolts. Also shown on Fig.3 is the small rightangle bracket (2 required) needed to connect the balun box to the dipole boom. These can be made from a scrap of aluminium. Making the balun The balun box provides a correct Two antenna U-bolts and clamps are required for a secure installation on the mast. The cable is passed through the dipole boom and is anchored to the mast with cable ties to stop it flapping in the wind. 28 SILICO N CHIP termination for the antenna dipole and terminals for the 75Q coax cable, all sealed away from the elements for protection. Inside is a PC board which accommodates the air-cored balun and 75Q coax connection points. The PC board measures 40 x 34mm and is coded SC02106911 . It has a very simple pattern. The balun is made of two small coils of 0.7mm enamelled copper wire, as shown in Fig.6 and Fig.7. Another view of the balun box, showing the four screws & nuts attaching the dipole elements. Stainless steel screws are mandatory here, since they attach to aluminium at one end & the copper balun board at the other. BILL OF MATERIALS Antenna 1.4 metres of 19mm square aluminium tubing with 1.15mm wall thickness 16 metres of 10mm x 3mm aluminium flat (length based on purchasing aluminium in 2 or 4-metre lengths) 1 350mm x 150mm x 1.6mm aluminium sheet (see text) 60 pop rivets, 3.2mm x 10mm, aluminium or stainless steel mandrel; or 60 stainless steel self-tapping screws (see text) 2 U-bolts & V-clamps to suit mast {F) HALF DIPOLE 2 REQUIRED MATERIAL:· 1.6mm ALUMINIUM Balun Box 1 plastic zippy box, 80 x 52 x 30mm 1 PC board, code SC02106911 300mm x 0. 7mm diameter enamelled copper wire 6 stainless steel machine screws, 3mm x 12mm 12 3mm stainless steel nuts <at> <at> A A 15 BOX LID DRILLING FOR DIPOLE MOUNTING +A 15 15 <at> 15 <at> (G) Miscellaneous 75Q semi-air spaced coaxial cable (Hills SSC-32 or equivalent), plastic cable ties, silicone sealant, Delrin plugs for square tubing . t}- . cp ~ . DIMENSIONS IN MILLIMETRES BOX BOTTOM DRILLING ~ HOLES:- A. 3.2mm DIA. B: 8mm DIA. Use wire with self-fluxing enamel for this job. Self-fluxing enamel melts easily in a solder pot or with a soldering iron and is much easier to work with than high temperature wire enamels which must be thoroughly scraped off before the wire can be tinned with solder. Wind the primary coil on a 3.2mm former (such as a drill bit) and then tin the ends. Similarly, wind the secondary coil on a 4.76mm former (a 3/16-inch drill) and then tin the ends. The primary coil fits inside the secondary coil before they are both soldered to the PC board. Incidentally, do not think that the connections to the outer coil, as shown on Figs.6 & 7 are a mistake. They are correctly shown, with both ends soldered to earth. Fig.5 , the dipole and balun box assembly, shows how the PC board is mounted inside the plastic box. Stain- Fig.4: cutting and drilling details for the half dipole elements, and plastic balun box. Note that thinner material could be used for the dipole halves, down to 1mm thick. Cut them out using a hacksaw & then carefully smooth the edges of each dipole section using a file. (G) BALUN PCB (!) (D) (F) Fig.5: this diagram shows the assembly details for the dipole boom, balun box and dipole elements. Note that stainless steel screws must be used for the balun PC board connections. The balun box is attached to the boom using two right-angle brackets. ]UNE 1991 29 BALUN & ___1-----=r"'='=°="'.. _TO RECEIVER ANTENN~-~PR_l ___ ~ SEC PRIMARY: 12T, 0.7mm ENAMELLED COPPER WIRE CLOSE WOUND ON A 3.2mm DIA. "MANDREL SECONDARY . 6T, 0. 7mm ENAMELLED COPPER WIRE CLOSEWOUND ON A 4.76mm OIA. MANDREL Fig.6: the circuit of the balun is typical of commercial practice and involves two concentric air-cored windings with the secondary being a shorted connection. e COILS MOUNTED ON COPPER SIDE OF BOARD SECONDARY SLIPPED OVER ONE END OF PRIMARY AND BOTH ENOS SOLDERED TO EARTH Fig. 7: wiring details for the balun PC board. Good quality semi-air-spaced 75Q coax with a woven copper shield is mandatory here. Aluminium shielded cable is not suitable for this job since you can't solder to it. less steel screws are used to attach the dipole halves and the PC board to the lid of the box. The box itself is attached to the antenna using the two brackets depicted in Fig.3(E). Don't fit the dipole/lid assembly to the box at this stage - that can wait until the antenna is about to be installed. Final assembly Now to put it all together. The two reflector grilles and the dipole boom are riveted or screwed together using the two mast clamping brackets. The idea is to pop rivet (or screw) the two mast clamp brackets to one of the reflector booms first. That done, pop rivet in the dipole boom and finally, the second reflector boom assembly, so that the dipole boom is sandwiched between the two reflector booms. You can seal the ends of the reflector booms with square Delrin plugs which are made for the job. At this stage, you're just about finished. Installation Take a lot of care when installing the antenna. There's no point doing a wonderful job of making the antenna if you end up in hospital after falling off a ladder. Believe us, climbing ladders while carrying an antenna is dangerous work, The first step in installation is to decide where to mount your antenna. For best results, mount it as high as possible and well clear of trees and other antennas. It is not really practical to mount this large corner reflector antenna on the same mast as a VHF antenna un- _J Fig.8: the PC pattern for the balun box is quite simple. You can either etch your own board· or buy a ready-made board from the usual suppliers. less it is vertically separated by a distance of at least one metre. In any case, if all goes well, you should be able to dispense with your VHF antenna altogether. Having erected your mast or J-pole (for barge board mounting) you should be ready to take the antenna up and secure it with the U-bolts. But just before you do that, you need to terminate the 750 coax cable. Pass the cable through the dipole boom and through the balun box. Strip the cable and tin the centre wire and shield, then solder it to the relevant pads on the PC board. Finally, place a cable tie around the cable as a strain relief (as shown in one of the photos) and then screw the dipole/lid assembly onto the case. You can now bolt the antenna to the mast. Use good quality cable This view of the balun box lid shows how the antenna cable is soldered to the balun PC board. A plastic cable tie around the end of the cable stops it from being pulled out of the box. 30 SILICON Cf/11' By the way, for minimum signal loss and good cable life, we recomm end Hills semi-air-spaced cable (with holes in the cable dielectric), type SSC-32 or equivalent. It's also a good idea to keep this cable as short as possible to minimise cable losses, so try to site the antenna close to your TV set. Secure the cable to the mast with plastic cable ties to stop .it flapping in the wind. You may also like to seal the balun box and the rear cable entry to the antenna with silicone sealant, to weatherproof it. Depending on where you live, painting the antenna may be worthwhile, particularly in seaside areas or industrial areas where there is a lot of fallout. In these cases, we suggest painting the antenna with an etch primer and then finishing with an aluminium loaded paint such as British Paints "Silvar". SC End of Financial Year Savings ~-------------------------------~ -----, Drive 1 Famous Brand ROCTEC External I Toshiba 1.2Mb external floppy drive (Complete with cables etc.) I Save $100.00 Now only $299.00 I Enquire about our entire range of external drives 1 I I I \.~------------------------------------J VIDEO CARDS 286-121\lllz Motherboard EGA plus Hercules WAS$149.00 NOW $50.00 VGA 16 Bit 256K WAS $199.00 SAVE$50.00 Was$299.00 NOW$149.00 VGA 16 Bit 512K WAS $299.00 NOW $199.00 This month $249.00 HIGH QUALITY, ELECTRONIC SOLUTIONS SYSTEMS r-------------------------------------, (Other Systems available - Please Call) 386-33:MHz 64KCache 286-12:MHz 386SX-16MHz Includes: Includes: lMbRAM 1.2Mb Floppy 42Mb Hard Drive 16 Bit 256K VGA card Enhanced 101 keyboard Serial, Parallel and Games port Hinged Baby AT desktop case and 200WPSU 14in Super VGA Colour Monitor 1Mb Ram on board 1.2Mb Floppy drive 42Mb Hard Drive 2 Serial, 1 Parallel port 16Bit 256K VGA card Enhanced 101 keyboard Desktop or mini tower case and 200WPSU 14in Super VGA Colour Monitor 1Mb RAM on board 1.2Mb Floppy Drive 42Mb Voice Coil Hard Disk 2 Serial, 1 Parallel Ports 16 Bit 256K VGA card Enhanced 101 keyboard Desktop or Midi Tower case with LED display and 200W power supply 14 in Super VGA Colour Monitor $2395.00 $3395.00 J ___________ \. ___________ _ $1795.00 ------------ YOUR GUARANTEE OF SATISFACTION: Includes: GOVERNMENT & WHOLESALE ENQUIRIES WELCOME * All products carry a 14 day money back guarantee ( except software and hard disks). * All prices include sales tax. * All motherboards carry a full 12 month warranty. * All cards come with full documentation * AU other products carry a fu ll 3 month warranty. Due to Technical advances, products we supply may in some cases vary from those pictured. In all cases the products supplied are guaranteed to perform to an equal or higher sUindard than those pictured : a~lfflltD11111G ~~ -r I Electronic Solutions Sales P/L 5 Waltham St Artarmon 2064 PO Box 426 Gladesvi lle 2111 li I h e ep one: (02) 906 6666 Fax: (02) 906 5222 1 1 •=c ~e"'i991Su;~;;;~er=~~;;~ai'"=='o~; :-w~~1~i;, :nau7th1s coupon to receive your FREE copy: Mr/Mrs/Ms: _ __ _ _ _ __ _ _ _ __ __ Address: _ _ _ __ _ _ __ _ _ _ _ _ __ I Suburb:_ __ _ _ _ _ _ State: _ _ __ Postcode:_ __ I Note: Please do not send back this coupon if you purchased from us in 1990 or returned the I previously issued card to be included on Lhe mailing list, you will receive the catalogue automatically. . 06/91 .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. u 2oouii 5V SENSE RSC 0.33!1 ~ 01 MR504 03 MTM20N10 05 2N3905 +12V 3.3k 5.6k o1 2N3905 1% 1000 16VW 03 MRB50 + 1000 _ 16VW + _ OUTPUT .01 3.9k 10/i;, 4.7k 02 2N2222 15k LIMIT 680!1 04 2N2222 IC2 555 DEAD TIME ADJ VR110K RSC= o.6vnsc .01 .0056 5V switchmode power supply This switchmode power supply provides 5 volts at up to about 1.5 amps with good efficiency. As presented, it is mains-powered but could run from a 12V battery. The circuit consists of four sections: a comparator (ICl), oscillator (ICZ), current sensing (Q5) and the switching FET (Q3). IC1 is an LM311 voltage comparator with a +5V reference at its. pin 3 as set by trim pot VRZ. This is compared with +5V from the output, Discharger for nicad battery packs If you want to maintain the full capacity of your nicad cells for repeated charge/discharge cycles , you need to ensure that they are fully discharged before recharging takes place. This can be a real problem in critical applications such as model aircraft where the remaining flight time needs to be known. 32 SIUCCJ N CHIP at pin 2, and the output at pin 7 switches high or low accordingly, turning off Ql when pin 2 is above pin 3. ICZ is a 555 timer connected in astable mode and running at about lOkHz. It drives QZ via a 680Q resistor and this transistor controls FET Q3. When both Ql and QZ are on, Q3 is also on. D3 is a flyback diode for Q3 and the output pulses are filtered by toroid Ll and the two lO00µF capacitors. Short circuit protection for the circuit is provided by Q5 and Q4. Q5 monitors the voltage across resistor Rsc and if it exceeds 0.6V, Q5 and Q4 turn on to rob the gate voltage from Q3 and so limit the current. This causes Q3 to come out of saturation (and therefore dissipate more power) and so a heatsink will be required. Steve Garland, Maroubra, NSW. ($30) Editor's note: this circuit could be improved by changing the current limit section to give foldback protection. This could be done by using Q5 to vary the voltage at pin 5 of ICl and thereby vary the duty cycle of Q3 . This circuit was designed to discharge a 4.8V receiver battery pack (4 cells) and a 9.6V transmitter pack (8 cells). In each case, the end point voltage is considered to be 1. 1V per cell, giving 4.4V for a 4-cell pack and 8.8V for an 8-cell pack. The circuit can be considered to be essentially a Schmitt trigger which monitors the voltage of the battery pack. It is biased so that when the end-point of the battery pack is reach- ed, it switches off discharge transistor Ql. ICl is a 4011 quad 2-input NAND gate package. When power is first applied, the outputs ofIClb and IClc are low and Ql is off. Pin 1 ofICla will be low and pin 2 will be high or low, depending on the setting of VRl. We'll describe how VRl is set in a moment but consider that it is set so that pin 2 is slightly more than ½Vee. When start button Sl is pushed, NiC•~BATTERY 4.8V R1 HEAVY DUTY TV/SPEAKER WALL-CEILING BRACKETS 9.6V R1 180 5W 390 5W R2 3300. 0.5W 4700 0.5W R3 6800 2.2k R4 10k 4.7k ; .... . · ... ·· • .. . .. .... 1 pin 1 ofICla is pulled high and so pin 3 goes low. This causes the outputs of IClb and IClc to go high and so Ql turns on to discharge the battery pack via resistor Rl. The LED is also illuminated to indicate that the discharge cycle is in progress. Note that since pin 4 is now high, pin 1 will stay high too, pulled up via the 47kQ resistor. And pin 2 will be pulled higher than its initial setting because of its associated 4 7kQ resistor. As the battery pack discharges , the voltage at pin 2 will gradually fall until eventually it goes below the gate threshold. This will cause pin 3 to switch high and, in turn, pin 10 will go low and switch offQl, thus ending the discharge cycle. To set the circuit up, connect a power supply and set it to the nominal voltage of the battery pack. Press S1 and adjust VRl so that the LED goes out when the power supply is reduced to a setting which is equivalent to 1.1 V per cell. The nominal discharge current is around 230 milliamps. J. Novak, Hoppers Crossing, Vic. ($30) The M~'-' and Mi " are heavy duty two platform mounting brackets • designed for securing small TV's and speakers to walls, ceilings, desks or bench tops. When mounted both units can ~:;;_Jt~ }~'~"fit. as well as being swivelled up or down to any viewing or listening angle. The metal platforms have predrilled holes for mounting and are easily adjusted with a large al/en key supplied with the unit. ·1 Imported and distributed by: ARISTA ELECTRONICS Available through the following retailers: David J Reid All Electronic Electronics. Components. 127 York Street. 118 Lonsdale St. Sydney. 2000. Melbourne. 3000. NSW. (02) 267-1385. Vic. (03) 662 3506. D2 FR604 SOLAR P A N E L + o - - - < 1 1 - - - - - - - - - - - - - - - - - - - - - - - - - + - N - t - - , DISCO SPECIAL INCREDIBLY PRICED R5 100k 15k R1 100k + T BATTERY : ...L. BIGGER LASER Put a new dimension into your light show Under ~1 J R6 100k ~ 10k R2 LEk . __,:,. COMMON-0-----------------------------~ Shunt controller for solar panels This shunt regulator circuit for a solar panel was designed in preference to a series regulator to avoid the inevitable voltage between collector and emitter of the regulating transistor. It avoids serial voltage loss apart from that across the polarity protection diode, D2. ICl is connected as an inverting amplifier with a gain of 100. It has a +2.5V reference at its pin 2 input while pin 3 monitors the output of the circuit via a voltage divider consisting of Rl and R2. Depending on how much the voltage at pin 3 exceeds the reference at pin 2, transistors Ql and Q2 are turned on to shunt away excess current from the solar panel. For best results, R3, R4, R5 and R6 should be matched to within 1 % or better. VRl is adjusted for around 14.4V across the battery at full charge. Provided a suitably large heatsink is fitted to Q2, the circuit can handle the output of a solar panel rated up to 50 watts. Diode D2 must be able to handle the full current from the panel. Peter King, Coffs Jetty, NSW. ($30) ½price ONLY: $580. 00 * 12 - 14 V D.C. supply, at approx 2A is all youneedtopowerthis ?mW HE-NE (RED) head and power supply. *Large head. We have other laser accessories and lasers both mains and D.C. powered. They all have one thing in common : U BELIEVABLE PRICES only at: OATELV ELECTRONICS Telephone: (02) 5794985 Fax : (02) 570791 o Cert. Post and Packaging $5.00 Mastercard, Bankcard, Visa Government Orders accepted JUNE 1991 33 -:j ~~/• ~ ~ 1 \ ~ "~~~ ({{j) ~~ tJL~ i /• ~ IT Ii,✓ -~ ) / ~ ~ ,_ . RITRON QUALITY RITRON POWER ~~ / ( l ill ,,.. . RITRON ~, ~ ~iIIUII !ii~ ,,.;J.,7,, ~ ~ 80286-12 CPU 1 MEG RAM EXPANDABLE TO 4 MEG 16Mhz LANDMARK SPEED TEST 1.2M JAPANESE BRAND F.D.D 42M HARD DISK DRIVE 28ms ACCESS 101 EXTENDED "CLICK" KEYBOARD JAPANESE KEYBOARD SWITCHES MINI CASE & 200W POWER SUPPLY 256K VGA CARD SUPA VGA COLOUR MONITOR (1024 x 768 res) SERIAL, PARALLEL, GAME PORT 2 YEAR "AUSTRALIAN" PARTS & LABOUR WARRANTY DOS 4.01. IBM' COMPATIBLE SPREADSHEET, WORDPROCESSOR & DATABASE SOFTWAR.E INCLUDED: ASSEMBLED& TESTED RITRON 1 MEG RAM EXPANDABLE TO 4 MEG 21 Mhz LANDMARK SPEED TEST 1.2M JAPANESE BRAND F.D.D 42M HARD DISK DRIVE 28ms ACCESS 101 EXTENDED "CLICK" KEYBOARD JAPANESE KEYBOARD SWITCHES MINI CASE & 200W POWER SUPPLY 256K VGA CARD SUPA VGA COLOUR MONITOR (1024 x 768 Res) 2 SERIAL, PARALLEL, GAME PORTS 2 YEAR "AUSTRALIAN" PARTS & LABOUR WARRANTY DOS 4.01. IBM' COMPATIBLE SPREADSHEET, WORDPROCESSOR & DATABASE SOFTWARE INCLUDED. RITRON EXECUTIVE ( }> a&lttaa '7 Li I I ~I :::::==---' ~ J ; ~ ~ ? ~ ~ -R ITRON EXECUTIVE ;.!~: $3,195 ASSEMBLED & TESTED IN AUSTRALIA. I• I / ,,-. ._. iii,,, . -~ / _ '8 ® ~=--· (---------\3Sg~II • · · · ·~ ~ ~ "' " \ \ ~'\ ~ ,~•• ◄ -~ -~-~ ·:=-J' 80386-25 CPU CACHE ON BOARD MEMORY 1 MEG RAM EXP TO 16 MEG 41 Mhz LANDMARK SPEED TEST 42 MEG HARD DISK 28ms ACCESS TIME 1.2M JAPANESE BRAND F.D.D 101 EXTENDED "CLICK" KEYBOARD SERIAL PARALLEL GAMES PORTS SUPA VGA COLOUR MONITOR (1024 x 768 Resolution) MINI CASE & 200W POWER SUPPLY 1 MEG VGA CARD (256 COLOURS) DOS 4.01 IBM' COMPATIBLE 3 YEAR "AUSTRALIAN" PARTS & LABOUR WARRANTY SPEADSHEET, WORDPRCESSOR & DATABASE SOFTWARE INCLUDED. ASSEMBLED & TESTED IN AUSTRALIA. 1 ~.., .,;,.. ~. .. ) I· $2,295 ~_.. '----------------'/ -~ ASSEMBLED& TESTED IN AUSTRALIA. )~ ;f;} i. r_;JJ ~ ~( 1/ , - ~ . ~ $3,495 80386-33 CPU ' - - - - - " " " " ' 32K/64K CACHE ON BOARD MEMORY 1 MEG RAM EXP TO 16 MEG 56Mhz LANDMARK SPEED TEST 85 MEG HARD DISK 18ms ACCESS TIME 1.2M JAPANESE BRAND F.D.D 101 EXTENDED "CLICK" KEYBOARD SERIAL, PARALLEL, GAMES PORTS SUPA VGA COLOUR MONITOR (1024 x 768 Resolution) 1 MEG VGA CARD DOS 4.01 MINI CASE & 200W POWER SUPPLY 3 YEAR "AUSTRALIAN" PARTS & LABOUR WARRANTY I SPEADSHEET, WORDPROCESSOR ! & DATABASE SOFTWARE INCLUDED. ASSEMBLED & TESTED IN AUSTRALIA. D:::; ; RITRON RITRON EXECUTIVE 80486·25 CPU ON BOARD CACHE. 4 MEG OF RAM 115Mhz LANDMARK SPEED TEST 85 MEG HARD DISK 12ms ACCESS TIME 1.2M JAPANESE BRAND F.D.D 3.5" 1.44M JAPANESE BRAND F.D.D 101 EXTENDED "CLICK" KEYBOARD SERIAL, PARALLEL, GAMES PORTS 1 MEG VGA CARD VGA COLOUR MONITOR (1024 x 768 Resolution) DOS 4.01 IBM' COMPATIBLE TOWER CASE & 220W POWER SUPPLY 3 YEAR "AUSTRALIAN" PARTS & LABOUR WARRANTY SPREADSHEET, WORDPROCESSOR & DATABASE SOFTWARE. 2 J.~95 $5,995 0 MAIL ORDER HOTLINE : 008 33 57 57. HEAD OFFICE: 56 RENVER RD, CLAYTON . PH: (03) 543 2166. FAX (03) 543 2648 CITY 48 A'BECKETT ST. MELBOURNE. PH . 663 6351 / 6391640. FAX: 6391641. NORTHCOTE 425 HIGH ST. NORTHCOTE, PH. 489 8866. FAX: 489 8131 . SYDNEY:74 PARRAMATTA RD, STANMORE. PH: (02) 519 3134. FAX : (02) 519 3868 ALL PRICES INCLUDE SALES TAX :Y: v- > INAUSTRALIA. IDEAL C AD MACHINE! MELBOURNE DEALERS GREENSBOROUGH COMPUTERS 103 Grimshaw St, Greensborough. .. 434 6166 Ph: (0 3) MICRODOT: 1T7"Sprlngvale Rd Nunawading. Ph: (03) 8941255 BLUESTAR COMPUTERS II ::E ffi 271 Maroondah Hwy, Ringwood Ph: (0 ) 3 870 1800 $8 995 ~~ 1 "' ~ ·· . t_/ ,._ . -1t.,__ ,. •• ' .. ..-:;;_~/ _,0 ' • _;:..'- ,;- . ,/ J Errors & omm,ssons excepted Prices & specil1catlons subject to change. "IBM, PC, XT, AT, are registered trademarks of International Business Machines. ~ ~ ~~~/4~~ -\it tt ·-- -.;__ ) 11 -~ '. '-. .·~~ er 1 /Iii,""'· = \~ ~ ~ ll)r' ----== _ •__ ~ ~L---_rr:i---"._ ~~-- ~ •' All sales tax exempt orders & wholesale mqumes ' , to · RITRONICS WHOLESALE 56 Renver Rd, Clayton, Victoria Ph · (03) 543 2166 Fax (03) 543 2648 MAIL ORDER & CORRESPONDENCE P.O BOX 620, CLAYTON, VICTORIA. 3168 -------------- ~-.., .I PLEASE QUOTE THIS ADVERTISMENT FO. R THESE GREAT. PRICES! . lirnl •'~ ,/,t \ .~~ r~•~ /,,1/• ----=----- _ 80486-33 CPU ON BOARD CACHE. 4 MEG OF RAM 157Mhz LANDMARK SPEED TEST 200 MEG HARD DISK 12ms ACCESS TIME 1.2M JAPANESE BRAND F.D.D 3.5" 1.44M JAPANESE BRAND F.D.D 101 EXTENDED "CLICK" KEYBOARD SERIAL, PARALLEL, GAMES PORTS 1 MEG VGA CARD L'--'" -~VGA COLOUR MONITOR (1024 x 768 Resolution) ~~..;·., \ DOS 4.01 IBM' COMPATIBLE , • . TOWER CASE & 220W POWER SUPPLY f 3 YEAR "AUSTRALIAN" PARTS & LABOUR WARRANTY . " SPEADSHEET, WORDPRCESSOR & DATABASE SOFTWARE. · ASSEMBLED & TESTED • WITH$ 6 , 9 9 5 E (l ms) _,,, ROD IRVING ELECTRONIICS Est. 1977. ~ 80386SX-16 CPU 42 MEG 28ms HARD DRIVE 1.2 MEG 5 1/4" DISK DRIVE 1MEG RAM exp to 4 MEG 16 BIT 256K VGA CARD SUPA VGA COLOUR MONITOR (1024 x 768 Resolution) SERIAL, PARALLEL, JOYSTICK PORTS MINI CASE & 200W POWER SUPPLY 101 KEYBOARD WITH DOS 4.01 IBM' COMPATIBLE 3 YEAR AUSTRALIA PARTS & LABOUR WARRANTY SPREADSHEET, WORDPROCESSOR & DATABASE SOFTWARE INCLUDED. 80386-25 CPU NO CACHE 1 MEG RAM 32Mhz LANDMARK SPEED TEST 42 MEG HARD DISK 28ms ACCESS TIME 1.2M JAPANESE F.D.D 101 EXTENDED "CLICK" KEYBOARD SERIAL, PARALLEL, GAMES PORTS 256K VGA CARD SUPA VGA COLOUR MONITOR (1024 x 768 Resolution) MINI CASE & 200W POWER SUPPLY DOS 4.01 IBM" COMPATIBLE 3 YEAR "AUSTRALIAN" PARTS & LABOUR WARRANTY SPEADSHEET, WORDPROCESSOR & DATABASE SOFTWARE INCLUDED. $2,595 RITRON $3 ,695 1/ ~ · 2 . (;~~~;;) ;~ t=-~~~!! C4~!il~tl lf .~- t ;J7 ~ _ $1,950 ASSEMBLED& TESTED IN AUSTRALIA 80386SX-20 CPU 1 MEG RAM EXP TO 4 MEG 27Mhz LANDMARK SPEED TEST 1.2M JAPANESE F.F.D 42M HARD DISK DRIVE, 28ms ACCESS 101 EXTENDED "CLICK" KEYBOARD MINI CASE & 200W POWER SUPPLY 256K VGA CARD SUPA VGA COLOUR MONITOR (1024 x 768 Resolution) SERIAL PARALLEL GAMES PORTS 3 YEAR "AUSTRALIAN" PARTS & LABOUR WARRANTY DOS 4.01,. IBM" COMPATIBLE SPREADSHEET, WORDPROCESSOR & DATABASE SOFTWARE INCLUDED. _1 RITRON ••!!!~!~!, '~ ,...,. ~: ,~~r·~t., $1 ,795 RITRON ASSEMBLED & TESTED IN AUSTRALIA. - , l 1 ~ / / . - ..... : '-·' ~ \ C r 1-9 Boxes 3 1/2"0D $19.95 3 1/2"HD $45.95 ~ :,, ALL PRICES PER PKT/BOX OF TEN $18.95 $42.95 •' 51/4"0D 51/4"HD /· . S DIFFERENT COLOURS OR 1 SINGLE COLOUR! 10 DS/DD COMES WITH A FREE PLASTIC DISK BOXI VERBATIM DATALIFE ONLY $8.95 1-9 10+ 3 1/2"0D $28.50 $27.95 3 1/2" DD $23.95 $22.95 3 1/2"HD $53.50 $52.50 3 1/2" HD $39.95 $37.95 5 1 /4" DD $22.95 $21.95 5 1/4" OD $12.95 $11.95 5 1/4"HD $27.95 $26.95 51/4" HD $19.95 $18.95 1-9 Boxes 10+ VGA GRAPHICS CARD (0 to 1 M 42 MEG HARD DISK FOR XT 28 ms ACCESS WITH IDE/FDD CONTROLLER .............................$549 42 MEG HARD DISK FOR AT 28 ms ACCESS WITH IDE/FDD CONTROLLER .............................$449 85 MEG HARD DISK FOR AT 18ms ACCESS WITH IDE/FDD CONTROLLER ........................... $749 126 MEG HARD DISK FOR AT 16 ms ACCESS WITH IDE/FDD CONTROLLER .........................$1,295 200 MEG HARD DISK FOR AT $595 RITRON EXECUTIVE BASE STATION. BUILT-IN FUNCTIONALITY & FLEXIBILITY DESIGNED INTO A SMOOTH COMPACT CASE $995 • Absolute IBM compatability • 286-12 MHz0WAIT \.."{ •1MBRAM • 40 MB Hard Disk/Cont • VGA Card • 2 x Serial/Parrallel/games ports • Real Time Clock/Calander • Dynamic Speed Co.ntrol provides Turbo Speeds • Keyboard speed ..,,eel ott At home, on you deak or in the network, the Ba~e Station is today's reliable and stunningly beautiful computer solution. 12 ms ACCESS WITH IDE/FDD CONTROLLER..save $100.$1,595 X20090 ... ............. ,.. ,......(requires monitor) . .... , ..... , .. , .. •...•. $995.00 13 3 1/2" DRIVE KIT. Y.E DATA 3.5" 1.44/720/360 DRIVE All Hard Disk capacitie,; are formatted. IDE/FDD drives are already low level formatted so you only have to "F DISK" to high level format them. Please note you need DOS 4.01 to format these to their maximum capacity as drive "C" or otherwise you will have to partition as "C", "O", "E:", etc. II you have an earlier version of DOS. • 5 1/4" Mounting bracket • Power supply adapter • Cable adapter · • Floppy disk controller card which controls 1.44 /7 20/360 drives · -~ ~ l ' • Complete Instructi ons to install a 3.5" in your exi sting computer. Enjoy the higher density & easy handling of 3.5" floppy diskettes I C11915 ................... $295 ROD IRVING ELECTRONICS k I I I / ~ CITY: 48 A 'BECKETT ST, MELBOURNE NORTHCOTE: 425 HIGH ST, NORTHCOTE SYDNEY: 74 PARRAMATTA RD, STANMORE MAIL ORDER: 56 RENVI.R RD, CLAYTON ·, ._. ,, ' \. • PH: PH: PH: PH: (03) (03) (02) (03) 663 489 519 543 6151 8866 3134 7877 ~ ,·" FAX: FAX: FAX: FAX: (03) 639 1641 AS PHONE. (02) 519 3868 (03) 543 2648 All sales tu exempt 0rde 's • nd wholesale inquirtes to : i!ITRONICS WHOLE SALE 56 Aenver Road Clayton Phone 1031543 2166 13 hnes, FaK {03 ! 543 2648 Err0< s ana omossoons excepted Pnces and spec1hca11ons subte(:t to change ;:;,.,::;.:;•·x ;:;.~- ~ •::•: ;:::;0 ::,;;0 ....,... .. - m•• ·o~,., ,, ac,,,,..,,~ ()! !_ ,,n~ h•f O,,,,~ •- 008-"'!_5757 TOLL.FREE MAIL ORDER HOTLINE FOR CREDIT CARD ORDERS! ) . ~'~,, ·\~ )z_~~y; ·• \\\ ~-J~ -~~~ - ·- - ~ " V~ • . ~ ~ e / < ~; .\y ~ , '--, ·_.~ _··_ \r-Jl~, ~-~ "/~\ ~~··/ ~ ✓.,..- ~ .,.,.,.,ffl ~ .~ / \ ,..._ ~ ~ ~ { ~~ . .iiiW ~ ~) "}· · I ~ ::flllHll/JI/J= flll!/'1- LIGHTING DESK This 4-channel lighting desk is intended for theatre, disco and music group applications. It has heavy duty circuitry and is able to cope with spotlights rated up to 1000 watts or more. By JOHN CLARKE & LEO SIMPSON This 4-channel lighting controll er h as been designed and built for the rigours of commercial use. It has been designed in consultation w ith a professional lighting engineer and has the features normally expected by professional users . It is not intended for domestic use. If you want a lighting controller which can be h ooked up to your stereo system, check out the articles on the Discolight published in th e July 1988, August 1988 and October 1990 issues of SILICON CHIP. These days , no theatrical or musical group worth its salt would dream of putting on a show without a properly set up lighting system. Instead, the lighting is usually fully chorea- Main Features Operating features • Four channels • 60mm slider pots • Click action flash switches with integral LEDs • Separate dimming for each channel • Master dimmer control • Flash on each channel • Master dimmer for flash • 4-channel chaser • Master dimmer for chaser • Adjustable chaser rate • Single step for chaser • Chaser on and off • Flash switch LEDs mimic lamp display 36 SILICON CHIP Electrical features • 2400W or 3600W maxi mum lamp load for 4-channels • 2400W maximum lamp load on each channel • 40W minimum lamp load on each channel • 15A fused mains supply • Isolated tab Triacs for safety • 40A 600V rated Triacs • 7.5kV optocoupler isolation between control circuitry and 240VAC mains for e xtra safety • RF interference suppression • Preheat for lamp filaments • Industry standard 0-1 0V dimming control graphed, with the number of lighting or "scene" changes running into the hundreds for a full night's show. Normally, most of the lighti ng gear required must be hired , along with the services of an operator to set it up , run it and then take it down after the show. This can cost heaps but by building your own professional 4-channel dimmer and then setting up your own lighting, you can save lots of dollars. Features The SILICON CHIP 4-Channel Dimmer is suitable for all types of stage work. It is powered from a standard single-phase 240VAC outlet and depending on wheth er it is a 10 or 15amp circuit , can control a total lamp load of 2400 or 3600 watts. A similar limitation applies to any of its four output channels - ie, each channel is rated for a maximum lamp load of 2400 watts. The unit is easy to use, with all controls well spaced and logically placed on a sloping front panel. Dominating the front panel are eight fader pots and th ese are all 60mm types to ensure smooth control and ease of setting. In addition, each channel can be operated individually by means of "flash" pushbutton swi tches. These switch es each incorporate a LED to show what is happening w ith the lamps and their relative brightness. In operation, you can fl ash each channel up to any brightness level, as set by the "Flash Master" fader. Similarly, the "Channel Master" control fades all lights up or down, to or from their individual fade settings. Chaser The two chaser faders control the rate and lamp brilliance when the The 4-Channel Dimmer is built into a metal case with a sloping front panel & features 60mm slider controls to set lamp brilliance & chaser rate. The chaser can be set to operate automatically, or you can flash each channel manually using separate pushbutton controls. unit is operated in chaser mode. Firstly, the lights can be flashed to full brilliance or to an intermediate setting as set by the "Chaser Master" fader. In this mode, the four channel faders set the minimum brightness level. The speed of the chaser is controlled by the "Chaser Rate" slider which can be set anywhere between one flash per second and six flashes per second. Pushing the "Chaser Rate" slider down to its minimum setting turns the chaser off and you can then flash the lights sequentially under manual control using the "Single Step" button. The role of the "Chaser On/Off" button is self-explanatory. As a matter of interest, you can have all the above functions operating together if you wish, so the unit is very flexible. For example, you can set each channel to a different brightness and then you can superimpose chaser and flash operations together. Sound too far-fetched? Not at all. Professional operators use various combinations to obtain special visual effects. Big Triacs The Triacs specified in the output stages are rated at 40 amps each and have surge ratings as high as 600 amps. These ratings are far greater than will ever be needed during normal dimmer operation, even taking into account the surge currents through cold filaments (up to 10 times normal current). The reason why such rugged Triacs have been specified is to cope with the high fault currents that flow when the filaments of large (say 1000 watt) lamps blow. When the filament of a large lamp blows, the loose filament ends usually flail around and establish an arc between the main filament stems. This arc current can be very high - 100 amps or more - until the stem fuses in the lamp blow. Typical 8-amp Triacs , such as those used in ·our Discolight, are quite adequate for normal dimming applications but they can't withstand the heavy fault currents just described they blow before the stem fuses go. So 40-amp Triacs are mandatory. Lamp preheat We've just mentioned cold filament JUNE 1991 37 SLIDERS FLASH BUTTONS MAINS OUTLETS COMPARATORS (IC3) S1 each mains half-cycle to give high or low lamp brightness. This switching action can cause considerable interference to sensitive audio, radio and even video equipment unless it is adequately suppressed. Naturally, our 4-Channel Dimmer incorporates suppression circuitry. Block diagram +10V VR5 CHASER (IC2b ,IC5) RAMP GENERATOR (IC2a,IC1b) Fig.1: the 4-Channel Dimmer has four mains output sockets which are controlled by separate Triacs. The Triacs in turn are controlled by separate comparators. In operation, each comparator compares a ramp waveform with the DC level set by an associated slider control (VR1-VR4) & switches its Triac to control lamp brilliance. The Flash buttons override the DC levels from the channel faders, while the Chaser circuit can also override the DC level from the channel master control (VR5). surge currents and this is a really big problem with lamps rated up to 1000 watts or more. When full power is applied to the cold filament of a 1000W lamp, the initial surge current can be as much as 10 or even 15 times the normal value - up to 60 amps or more. While these huge currents don't last long (less than one cycle or 20 milliseconds), they cause very high stresses on the lamp filament, for two reasons. First, because a lamp filament may not have the same diameter throughout or it may be kinked (it is coiled anyway), it will inevitably have hot spots. As time goes on, these hot spots get worse and become weaker, as the filament material is boiled off. Second, a current of around 50 or 60 amps in a coiled filament naturally causes a high magnetic field and this can literally shake a weakened filament to pieces - a double whammy, if you like. To overcome this problem of surge current which is particularly bad during chaser operation, all lamp filaments are maintained in a preheated 38 SILICON CHIP state, just enough to make the filaments glow a dull red but not give off any appreciable light. This greatly increases the life of these very expensive high power lamps. As with any mains dimming circuit, the 4-Channel Dimmer uses phase control of the Triacs to vary the lamp brightness. In other words, the Triac is switched on early or late in Warning! This 4-Channel Dimmer is not a project for beginners. Unless you have already built a number of mains-powered projects, we advise you to leave this one strictly alone. Part of the circuitry is powered directly from the 240VAC mains and therefore must be regarded as potentially dangerous. The wiring conforms to SAA regulations and if constructed correctly it is a safe appliance to use. Although the 4-Channel Dimmer has quite a few control features, the basic circuit principle is fairly simple. The block diagram of Fig. l shows the general circuit arrangement. It depicts four output sockets which are controlled by four separate Triacs. Each Triac is controlled by a comparator and each of these is controlled by DC voltage from a slider. The inverting (-) input of each comparator is connected to a decaying ramp (sawtooth) signal which is synchronised to the 50Hz mains waveform (see Fig.2). Meanwhile, the noninverting (+) input of each comparator is connected to its own respective slider pot, VR1 -VR4. The DC level from the slider sets the brilliance of the lamps connected to the output. The comparator compares the DC level from the slider with the decaying ramp waveform at its non-inverting input. When the DC level from the pot is higher than the ramp waveform voltage, the comparator output goes high and turns on the Triac. Fig.2 shows this comparison process in a little more detail. It shows the mains 50Hz waveform at (a) and the decaying ramp waveform immediately below it at (b). Notice that the ramp waveform starts at a high level at the beginning of each mains half cycle and then decays to a low level by the end of the half cycle. Also shown on the ramp waveform plot (b) is the DC level from one of the sliders (applied to the non-inverting input of the comparator). Each time the ramp waveform drops below the DC level, the comparator output goes high and turns on the Triac. This is reflecfed in waveform (c) which shows the voltage applied to the lamp. Waveforms (b) and (c) are for a relatively high brightness setting so almost the full mains waveform is applied to the lamp. Waveforms (d) and (e) show the conditions for a low level of brightness. Here the DC level from the slider is lower and consequently the Triac is turned on later in each mains half cycle. Now refer back to the block diagram of Fig.1 and you will see that the · flash buttons can override the DC levels from the channel faders (or sliders). Each flash button is connected to the wiper of the "Flash Master" and also to the non-inverting input of its respective comparator. Chaser operation can also override the DC level from the channel masters. Accordingly, each of the four outputs from the chaser circuit connect to the non-inverting inputs of their respective comparators. Main circuit Now take a look at the full circuit diagram of Fig.3. The similarities to the block diagram of Fig.1 may not be readily apparent but we'll point them out. The four comparators in Fig.1 are contained in IC3, an LM339 quad comparator, on the main circuit. The four channel sliders (or faders) are shown as VR1-VR4 on the main circuit, while LEDs 1-4 on Fig.1 have the same numbers and function on Fig.3 but are associated with a bunch of transistors. Let's first talk about the ramp generator, which is one of the core parts of the circuit. It is based on comparator IC2a and associated components, at the top right of Fig.3. In reality, IC2a acts as a "zero crossing" detector and gives a pulse whenever the mains voltage sinewave passes through zero volts, once every 1 0 milliseconds. The zero crossing pulses are then used as markers for the beginning of each mains halfcycle. Diodes D5 and D6 rectify the AC voltage from the power transformer secondary and apply the resulting pulsating voltage via a voltage divider to the inverting input (pin 6) of IC2a. Pin 7, the non-inverting input, is connected to a voltage divider which gives a DC reference of about +60mV. Fig.6 shows the action. At the beginning (or end) of each mains half cycle, the voltage at pin 6 will drop below pin 7 and so the output of the comparator at pin 1 will deliver a brief +12V pulse. So you get a string of these pulses coinciding with the zero crossing points of the 50Hz mains waveform. These positive pulses are fed via diode D7 to a .039µF capacitor which (a) MAINS WAVEFORM 10V (c) WAVEFORM TO CH1-CH4 ;--•~..__ _ _ _ , _ _ _ _ __ LAMPS (d) FILAMENT BRIGHTNESS LEVEL IC1b RAMP FILAMENT BRIGHTNESS IC2c J I I (e) / .,, ,,.- BRIGHTNESS LEVEL I I I I MINIMUM LAMP t--,,,___ __. WAVEFORM ~ / I I Fig.2: this diagram shows the 50Hz mains waveform at (a), while immediately below it is the decaying ramp waveform (b).Also shown on the ramp waveform is the DC level from one of the channel sliders. Each time the ramp waveform drops below the DC level, the · associated comparator output goes high & turns on its Triac to produce the waveform shown at (c). Note that waveform (c) is for a relatively high brightness setting. Waveforms (d) & (e) show the waveforms for a low brightness setting. is shunted by a 100H2 resistor and 10V zener diode. The resultant waveform across the .039µF capacitor is the ramp voltage waveform depicted in Fig.2. It is clamped to a maximum of +10V by the zener diode and its rate of decay is set by the 100kQ resistor. The ramp waveform is then fed to pin 10 of IC1b which functions as a unity gain buffer to drive the inverting inputs (pins 4, 6, 8 & 10) of IC3, pin 11 of IC2c and pin 9 of IC2d. 10V slider supply In the specification panel, we make mention of the fact that this 4-channel Dimmer uses the industry stand- ard 0-10V dimming control voltage. What's so important about this? Well, it could be important if you want to use this lighting desk to control a commercial lighting rack or "slave" another lighting desk to it. So all the fader controls in the circuit am fed from a common +10V supply which is derived from the +12V rail via 5kQ trimpot VR9 (near IC2d). This feeds master faders, VR5, VR6 & VR7. The output from the wiper of each of these master faders is buffere d by an op amp - IC1d for VR5, IC1a for VR6 and !Clc for VR7. Actually, IC1c isn't really necessary but we've used JUNE 1991 39 it anyway otherwise we would have had an op amp left over. These buffer op amps prevent loading effects by the following circuitry. ICl, an LM324 quad op amp (ie, four op amps in a single package), is an important choice for these buffer amplifiers. Not only is it cheap but it can operate from a single rail supply and its output can go right down to OV which is desirable for this circuit. <at>+ Channel faders ~~ The four channel faders , VR1 -VR4 , all connect to the output of the master level buffer, ICld. In turn, the wiper of each channel fader connects to the normally closed contact of its associated Flash switch, S1-S4. The other side of each Flash switch connects via a lOkQ resistor to the non-inverting inputs of IC3d, IC3c, IC3b and IC3a respectively. IC3 is an LM339 quad comparator. Its inverting inputs (pins 4, 6, 8 & 10) are fed with the ramp signal from pin 8 of IC1 b, as noted above. And as described previously, in relation to block diagram Fig.1 and waveform diagram Fig.2, the outputs of these comparators drive the Triacs to deliver high or low power to the lamps. In practice, the IC3 comparators don't drive the Triacs directly, as there are gates, transistors and optocouplers in the signal path to the Triac gates. However, the principle is true. ;~~r-::i cz:>u>CC:.:.: c.., :iE ~ :::c~ci::>o z U>~ I· a:ff3~ wz« ~~i a:o + ~ ;:: ~H•· :,:a:.., u:>~ ~ C, I· I· z ~~::i u>~ C, :,, c,~ ~+a, "' ,- a: IC = w:,, ..... - "' I· z :,:a:-' u>~ ;:: r- ---- - SILICON CHJP NN~ C:Cc.:, + Each channel can be flashed to a level set by the Flash Master fader, by pressing the relevant Flash switch (S1 , S2, S3 or S4). These switches disconnect th e signal from the relevant channel fader pots and connect the inverting inputs of the comparators to· the Flash Master fader output at pin 1 of !Cla. To prevent any contact bounce 40 ,. <n,- a: i:: Flash buttons Fig.3: all of the circuit elements shown on the block diagram can be directly related to the main circuit diagram. IC2a & IClb form the ramp generator, while IC2b & IC5 form the core of the chaser circuit. IC3a-lC3d are the comparators & these drive the Triacs via NOR gates IC4a-1Cd, transistors Qt-Q4 & four MOC3021 optocouplers (IC9-IC12). IC2c forms the filament preheat circuitry, which limits the inrush current to the lamps. I· :c;;~ I I I I I , ~_ _ i _ _ _JI C, C, 3: +~i;; ·~•- ~ C, .,. ~ + z ~~ f-1•· ~I· --«-"' I a:~ w ~ <no~ :,:Z c..:,O ~ I• +12V ◄ • -◄ '\ RAMP r-- 16 SINGLE 1, STEP S5 r-- °+ +12V 3'7 04 BC557 1N4148 .i. 47kf , + 01:J: 12 13~ 6BO!l .,. IC71 14 •cK 1k-> 1 CH4 001:; ,- 21 . ~ FLASH 3 S3 _J,_ 1 +12V +12V IC12 MOC3021 ·5ao1 1 1kt 1t IC5 4017 SINGLE~ STEP }s LEDS i CH3 LED3 +12V +12V 1N4148 .i. ~ 01J CHAS.ER COUNTER .... u.i.... n,. ) ~ B 2'. CH2 LED2 _A2 ~ ~ +12V 5.6k )o3 Wit ) A ( Jrt A2 A~K 3 3k t t CH1 LED1 I 4-CHANNEL DIMMER A~~~~T 500~1 470kl. 05 BC547 l t TRIAC2 , 06040J7 ; ~ 0.22 .:., 250VAC~ · AL~- ~'Y'• CH2 )// .,. 01 BC557 !C 680i2 A2 TRIAC1 06040J7 G 4v Iii 10k~06 FILAMENT HEATER ~ +12V 2.2kt 13 B lkf +12V +12V GNO (!) (!) A K· ,._ ..."" CASE 680!.l 1t FLASH 1 Sl u·3 )rtUT 02 BC557 A CE 13 Ee~·\ .,. 'C 10kf H }s 10k 10,4 VIEWED FROM BELOW CH3 K' 09 .____ A2 A FLASH 2 S2 15,R B 680ll s?r) ac~c B j: '1.:. .J,. LEDHED6 WITHIN S1-S6 LH4 18T . 0.8mm ENAMELLED COPPER WIRE ON NEDSIO 17·730-22 TOROID CASE problems, a .OlµF capacitor is connected to the non-inverting input of each comparator in IC3. Chaser operation The 4-Channel Dimmer is easy to build, with most of the parts mounted on two PC.boards. Because of the efficient switching technique employed to control the lamps, the case provides adequate heatsinking for the four Triacs. Fig.4: this CRO photograph shows the uncalibrated mains waveform at top & the ramp voltage from pin 8 of IClb immediately below (5ms/div & 5V/div). The ramp voltage decays from a peak to almost 0V over each half cycle. 42 SILICON CHI!' Essentially, only IC2b and IC5 provide the core chaser function but quite a bit of gating and logic is required to make it all work properly with the rest of the circuit. So IC6 , IC7, IC8 and IC2d also get into the act. Let's look first at IC2b which provides the chaser clock function. IC2b is one section of an LM339 quad comparator and it is connected as a Schmitt trigger oscillator. The 4. 7µF capacitor at the inverting input (pin 4) is charged and discharged via a 10kQ resistor which connects to a voltage divider comprising a 22kQ resistor, the lOkQ Chaser Rate pot (VR8) and a 2.2kQ resistor. When the wiper of VR8 is closest to the 2.2kQ resistor, the 4. 7µF capacitor charges and discharges quickly and when set near the 22kQ resistor, it charges and discharges slowly. But when the wiper of VR8 is set to the minimum setting, the 4.7µF capacitor cannot charge to the upper 8V threshold of the Schmitt trigger (set by the resistors at pin 5) and oscillation stops. The output of IC2b then latches high. LED 5, driven by IC7e, indicates when IC2b is oscillating. When IC2b's output is high, IC7e's output is low and the LED is off. When IC2b's output is low, the LED is on. Therefore, the LED is off when the oscillator is Fig.5: the top trace in this photo shows the waveform that's applied to the lamp when the dimmer is set for a high brightness level. Note that the mains in not switched to the load until it is almost half-way through each cycle. stopped and flashing when the oscillator is operating. IC2b also drives inverter IC7fwhich is used to clock IC5, a 4017 decade counter. Alternatively, IC5 can be clocked with single step switch S5 which is intended to be used when the Chaser Rate control is set to zero. The "0", "l", "2" and "3" outputs ofIC5 are used for the chaser sequence, while the "4" output at pin 10 resets IC5 at the count of five. Thus, IC5 's outputs go high at 0, 1, 2, 3, 0, 1, etc. These outputs are fed to AND gates IC6a-IC6d (4081) and these in turn drive comparators IC3a-IC3d via diodes D8-D11. The AND gates of IC6 work as follows. When the commoned inputs at pin 5, 2, g and 12 are low, the AND gate outputs are low and so chaser operation is not enabled. Conversely, when the commoned AND gate inputs are high, the chaser signals are fed through. Chaser brightness & enable When the Chaser mode is operating, the lamps can be made to flash at full brightness or at any level, depending on the setting of the Chaser Master fader (VR7) which is buffered by IClc. The voltage from this fader (and buffer IClc) is compared by comparator IC2d with the ramp voltage from IClb. IC2d's output is a pulse train which goes high either earlier or later in each mains half cycle, depending on the setting of VR7. . IC2d's output controls the reset mput offlipflop IC8a. This JK flipflop is connected so that when its Set input is high , the Q-bar output at pin 2 follows the Reset input. The Q-bar output is inverted by IC7c and drives the commoned inputs of AND gates IC6a-IC6d. When these inputs are high, the chaser signals from IC5 are gated through to stages IC3a-I_C3d. . When IC8a's Set input (pm 7) 1s low, its Q-bar output is high and the resulting low output from IC7c forces the IC6 AND gate outputs low. This turns the chaser function off. The control signal for the Set input of IC8a is derived from IC8b, the second JK flipflop in IC8. This flipflop is connected so that its Q output changes state on each clock pulse to pin 13. The Q output controls the Set input of IC8a while the Q-bar output drives LED 6 via IC7d to indicate when chaser operation is enabled. The clock sig- PARTS LIST 1 metal case, 274 (W) x 209 (D) x 55 (H front) x 100mm (H rear) 1 Dynamark front panel label, 271 x 206mm; or screen printed front panel 1 PC board, code SC 10106911, 201 x 158mm 1 PC board, code SC10106912, 160 x 67mm 4 10A panel mount mains sockets (Jaycar PS-4012) 1 15A 3AG panel mount mains fuseholder 1 15A 3AG fuse 1 SPOT 8A illuminated mains switch (Jaycar SK-0985) 1 2851 12.6V mains transformer 3 metres 10A mains cord 1 10A mains plug 1 3-way mains terminal block 1 mains cordgrip grommet 3 earth solder lugs 12 5mm ID rubber grommets 4 Neosid 17-730-22 iron powder toroid cores 2 8-way vertical pin headers (Jaycar HM-3210) 2 8-way right angle pin headers (Jaycar HM-3215) 4 8-way connector sockets (Jaycar HM-3220) 1 2-metre length of 12-way rainbow cable 8 10kQ 60mm travel linear slider pots (SV602NP 20A 1-B1 Ok) 8 knobs to suit sliders 6 PC-mount SPOT momentary action switches with LED indicator & 17.5 x 17.5mm black key 1 5kQ miniature horizontal trimpot 1 500Q miniature horizontal trimpot 20 3mm countersunk black dress screws 16 3mm grub screws 4 3mm cheesehead screws 20 9mm x 3mm tapped spacers 4 6mm x 3mm spacers 8 screws and nuts for mounting mains sockets 4 screws and nuts to secure main PC board 8 screws and nuts for Triacs , transformer and earth connections 2 screws and nuts for terminal strip 4 screws and nuts for securing toroids 4 plastic insulating bushes for mounting toroids 25 1mm PC stakes 6 cable ties 1 4-metre length 0.8mm enamelled copper wire 1 1-metre length 0.8mm tinned copper wire 4 rubber feet Semiconductors 4 Teccor O6040J7 40A 600V insulated tab Triacs (from NSD) 1 LM324 quad op amp (IC1) 2 LM339 quad comparators (IC2, IC3) 1 4001 quad NOR gate (IC4) 1 4017 decade counter (IC5) 1 4081 quad AND gate (IC6) 1 74C14, 40106 hex Schmitt trigger (IC?) 1 4027 dual JK flipflop (IC8) 4 Motorola MOC3021 7.5kV isolated Triac drivers (IC9-12) 1 7812 3-terminal + 12V regulator 6 1N4002 1A rectifier diodes (D1-06) 5 1N4148, 1N914 signal diodes (D7-012) 1 10V 1W zener diode 4 BC557 transistors (01-04) 2 BC547 transistors (05,06) Capacitors 1 1000µF 25VW PC electrolytic 4 10µF 16VW PC electrolytic 1 1µF 16VW PC electrolytic 4 0.22µF 250VAC mains rated 1 0.1 µF monolithic 1 .039µF metallised polyester 4 .01 µF metallised polyester 2 .001 µF metallised po lyester Resistors (0.25W, 5%) 4 470kQ 1 3.3kQ 3 100kQ 4 2.2kQ 2 47kQ 7 1kQ 1 22kQ 8 680Q 11 10kQ 1 220Q 4 5.6kQ Miscellaneous Solder, heatshrink tubing, heatsink compound , hookup wire. JUNE 1991 43 Each of the four output channels is capable of controlling loads up to 2400 watts, while the maximum total load for all four channels is 2400 watts for a 10-amp circuit or 3600 watts for a 15-amp circuit. nals for IC8b are derived via switch S6 and IC7a which is connected as a one-shot. Each time S6 is pressed, it either enables or disables the Chaser mode. At power up, the RC delay at the input of IC7b produces a reset pulse for flipflop IC8b, to reset it to "chaser off" mode. This means that the 4Channel Dimmer always powers up in Dim only mode, with the chaser function off. Filament preheat We 1ve already discussed the need for th e filaments to be preheated and you might think that this could be easily arranged by having a fixed resistor in the earthy side of the dimmer faders. However, it isn't quite as easy as that since LEDs 1-4 are supposed to indicate the lamp brightness and if the simple approach were used , the LEDs would also respond to the preheat Triac trigger pulses. Hence, the preheat facility works in a more complicated way. lt's ·based on comparator IC2c and the NOR gates ofIC4 (4001). IC2c works in similar fashion to the comparators of IC3. It compares the ramp voltage to a preset level from trimpot VRl0 and produces a pulse towards the end of each mains half cycle. IC2c's output pulses are then fed through to the Triac trigger circuits via the NOR gates. Each NOR gate drives a BC557 transistor (Ql-Q4) via a 5.6kQ resistor and the transistors each drive a MOC3021 optically isolated Triac driver (IC9IC12) via a 680Q resistor. The transis- +12V PULSE OUTPUT PIN1 , IC2a tars also drive the LEDs (associated with Flash switches S1-S4) which mimic the lamp display. To isolate LEDs 1-4 from the Triac filament preheat pulse, Q5 and Q6 come into play. Instead of the LEDs merely being connected to the 0V line, they all go to the collector of transistor Q6. Q5 is switched on each time the preheat signal from IC2c is high. This switches offQ6 and prevefits the LEDs from being turned on. At other times, when the preheat signal from IC2c is low, Q5 is switched off, Q6 is switched on and the LEDs respond to the signals from comparators IC3a-lC3d. Thus, the indicating LEDs are driven only when the brightness of a channel is set above the preheat level. As a result, the LED display provides a good indication of the brightness of the lamp setting. Each of the four Triacs in the circuit has an interference suppression circuit involving a 0.22µF capacitor and an inductor (Ll-L4) wound on an iron dust toroid. Note that our specifications show a minimum loading on each channel of 40 watts . This is necessary because the "holding current" specification for Q6040J7 Triacs is such that they won't turn on predictably for lamps oflower rating. So if you try testing this Dimmer with 25W lamps, it probably won't work correctly. Power supply Power for the dimmer circuit is derived from the mains and is applied via a 15 amp fuse and switch S7 to power transformer Tl. Note that the mains supply to the Triacs does not pass through S7 as the current would greatly exceed the switch rating. The 12.6V transformer secondary drives bridge rectifier Dl-D4 and this then feeds a lO00µF filter capacitor. The resulting DC voltage is then applied to a 7812 +12V regulator. Next month , we will complete the description of the 4-Channel Dimmer by giving the construction details. Acknowledgements Fig.6: this diagram shows how IC2a produces square wave pulses which are synchronised to the zero voltage crossing points of the mains. Each time the rectified 50Hz sinewave on pin 6 swings below the reference at pin 7, IC2a's output switches high. 44 SILICON CHIP Our thanks to the following companies for their assistance with this project: Jaycar Electronics, for the metalwork and other components; NSD Australia, for the Q60407 Triacs; and VSI Electronics Australia, for various Motorola !Cs. SC Y L,AH t:LC.L, EnU l"JIL,0.,JJ-\11...,/"lll LLLVlll'-Jl••vv,.,,, , ..., " ' -- ~---- YCAR YCAR YCAR YCAR ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS 1·CAR YCAR YC AR YCAR / CAR EU EU EU EU ELE YCAR Elf - JAYCAR JAYCAR JAYCAR JAYCAR ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS JAYCAR JA YCAR JAYCAR JAYCAR ·- · · · -- - ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS JAYCAR JAYCAR JAYCAR JAYCAR ,... , , , , ... . , .-- .- , ,..,.. ... ,....,..,. ~,.,... 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TS1428 J TS1429 ) TS1484 ) • TS1485 ) TH1880 J TH1882 ) TH1885 )TD2470 XV2060 J• XC3050 ) XC5092 Book: Home ElectricRecord CircuitsMake$$ 69.50 Book: 17.95 Book: Intro Digital Audio 17.95 Magnavox SW woofer 39.50 JC 8" polyconewoofer 49.95 Philips 8" woofer . 49.50 Magnavox 1O" woofer 1OW 43.50 Subwoofer 1Q" Etone 159.50 Scanner Roadrunner AR880 399.00 6mm x No 4 self tapper pkt 10 .75 lnsul staples pkt 100 .75 BNC skt insulators pkt 4 2.00 High energy rack case 129.50 Horwood 84/BV case 35.95 Horwood 84/12V case 44.95 Horwood 84/17V case 49.95 Bug cage for 6 bug boxes 8.95 Bug cage cover 5.95 Black/silver knob 2.50 Silver slider knob .95 Die cast heatsink BFNF 50mm 5.95 Die cast heats ink BFNF 75mm 8.95 Die cast heatsink BFNF 100mm 10.50 Die cast heatsink MF-14-2F-15036.95 Bishop graphics pads .156" 7.25 39.50 PPSPD02 9.95 64462 RF5c9Acpolaxug_-ssktolderless 9.95 ) PA0885 RS232 Surge suppressor 26.95 J PP0932 64 way PCB Cbody edge plug 29.95 ) PP0934 96way PCB C body edge plug 34.50 PP0936 32 way socket Cbody straight 29.50 { PP0938 64 way socket Cbody straight 109.50 PP0940 96 way socket Cbody straight 309.00 / PP0945 IDC header 16 way/strain rel .25 / PP0947 IDC header 26 way/strain rel .25 PP0948 IDC header 34 way/strain rel .50 PP0950 IDC header 50 way/strain rel 99.50 PP0952 IDC header 16 way rob nugent 19.95 PP0953 IDC header 20 way rob nugent 24.95 PP0954 IDC header 26 way rob nugent 29.95 PP0955 IDC header 34 way rob nugent 4.95 PP0965 IDC header 16 way right ang 3.95 PP0967 IDC header26wayrightang 1.20 PP0968 IDC header 34 way right ang .40 : / PP0970 IDC header 50 way right ang 3.95 } PA3588 Plug adaptor 6.5 mon plug 5.95 J to 6.5 star skt 6.95 } PA3597 Plug adaptor 6.5 star plug to 23.95 ( 2 x 3.5 star skt 3.95 ( PA3650 Plug adaptor PL259 plug to 1 1. 9 405 19.95 9.65 12.50 7.50 13.95 17.50 2.95 3.95 3.95 4.95 1.95 1.95 1.95 1.95 1.95 2.95 3.50 5.95 .9 45 0 9.95 3.00 5.00 3.00 4.00 6.00 .50 .75 .75 1.00 .20 .20 .20 .20 .20 .50 .50 1.00 J(YV7075 YT7070 1 7 7. 2 25 5 ,!AVC/, t-: JAYCAR JAYCAR JAYCAR JAYCAR J AYCAR > t ? ·•·•···=···•···•···•···•·· tt 3 3. 9 95 5 •.•.•,•.·. •,· •.·•·: •,•··. •..· • ··. •.· ·=·= Pl 63 DO 84 RCAp·isnktPLCC socket i:~~ 3.95 t~~ • • <• • • ~::~~ ~~~:~;~:it ;~~;~e~c skt Pl6558 40 pin OIL IDL plug/cover 3.95 t QP2220 Ph probe Hi quality Bishop graphics TOS T'sista patt 7.25 Bishop graphics T018 T'sista patt 7.25 Bishop graphics universal target 7.25 Bishop graphics tape .25" 25yd 7.25 Bishop graphics .1" edge connector 7.25 Bishop graphics .156" edge connector 7.25 Scotchcal 8001 alum/red 11.95 BSD guitar effects kit 115.00 Digital capacitance meter 85.00 Super timer kit 59.00 Remote for AM/FM tuner 99.95 PC-driven lune! generator 36.95 TTL-analogue video conv 49.95 PCB shorts locater 17.95 Metronome - beat me 29.95 RTTYencoder 29.95 Super simple modem kit 85.00 ·Et.EC l"rl'J N:CS ELECTRON ICS ELEC TRO NICS ELECTRONICS ELECTRONICS ELECTRONICS > t t t 3.95 3.95 3.95 3.95 7.50 85.00 54.75 39.00 49.95 22.95 29.95 11.95 17.95 14.95 49.00 >OM7206 BK mem desk databank > OM7240 Metronome - electronic ) RN3462 815 thermistor - glass } R05271 3.0 MHz Xtal ? R05285 8.0 MHzXtal ) R05291 10.695 MHz Xtal ) R05294 16.0 MHzXtal ) RC5367 .39µF 50V ceramic ( RC5375 470pF 400V ceramic f RE5810 3.3µF 25V RT electro j RE5815 4.7µF 25V RT electro J RZ6634 3.3µF 35V tag tantalum RZ6675 100µF 3V tag tantalum f RU6735 10,000µF 35V RP electro ( ST0566 Mini toggle Sw DPDT c/off J ST0567 MinitoggleSwDPDT c/off / • SP0745 12V ill um econ push sw > 1.95 4.95 3.95 2.95 j:~~ ) ) ) } < ELECTR :~ GS watch battery 2.95 Yellow 12V bezel Hi quality 6.95 Arlec super torch 44.95 Arlec fluoro lantern 99 95 Hot blow tip suit pro Portasol 15.95 Blowtorch tip suit pro Portasol 15.95 Adcola 530/CF6 tip .7mm chisel 12.95 Adcola 530/CF6 tip 1.5m chisel 12.95 6"diagonalcutter/plier 7.95 6" linesman cutter/plier 7.95 6" long nose plier 7.95 Mini drill - battery op 32.95 Bosch rotating vane 6 cyl 49.95 Lesson One learning aid 69.95 Philips 101 keyboard 99 OD Cordless waterproof phone Viatel model 1 ) YV7076 Viatel model 2 } YV7077 Viatel model 3 \ ZV1675 LM723T05 .,.,•,.,•.•,.,•.•,.,•.•,.,•.•,.•,. ZXTZT121ss VBCN 54 A9CF 2294 88 lT231 O ZN3566 } ZL3747 LM747 ZL3834 CA3100 • i ZC4000 4000 j ZC4512 4512 ZC4528 4528 } ZC4538 4538 } ZC4543 4543 } ZC4582 4582 •J ZC4583 4583 ZC4853 74HC157 } ZC4860 74HC240 / ZC4861 74HC241 / ZC4870 74HC368 .75 ZC4896 74HC4075 } ZC4902 74C02 1.50 ) ZS5033 74LS33 ) ZS5083 74LS83 < > > t > 1.00 .50 }} :~~ ZS5148 ZS5155 74LS148 74LS155 .50 2.00 29.95 69.95 9.95 9.95 6.95 6.95 3.95 3.95 3.95 19.95 35.00 25.00 59.00 • ELECT R • EL ECTR • ~~~g~ • ELECTR ' cL Ecrn ~~~g~ • EL ECTR • ELEcrn •~;~g~: • m cTR • El.ECTR • • ELEC~R • ELEc 1rn • El EC R ~~~g;: ~~~g~: 289.00 29.95 179.00 14.95 • cL EC TR 34.95 17.95 34 .95 18.95 ELEC"R 2.95 .95 E.EC'TR . 40 .10 4 95 1 00 EU' c rn .20 .06 mcrn 2.25 .60 4.95 2.00 EcECTR .80 .20 "LE<: rn 1.95 .50 1.75 .30 mcrn 1.75 .30 w ,c rn 2.65 .50 2.90 .60 mcTR 1.50 .20 FLFCTR 1.25 .25 ~t~f~~ 3.20 .40 FL ECTR 2.75 .30 2.95 .35 r LEc rn .95 .20 rcEcrn 3.95 .40 1.00 .30 ELEC TR 1.95 .30 ELE C TR ~C~g~: ~~~g;: ~t~g;: ~t~g~: ~t~g~: ~t~g;; ;t~g~ 3.95 1.85 .40 .40 2.95 2.20 2.95 2.90 . 1.25 .80 2.45 7.00 .50 .50 3.20 3.90 .40 .40 .30 40 .20 .30 .50 2.00 .10 .10 .25 1.00 ~t~g;: i:LF CHI i1.85: .35.~~ • i~m ~ mi~~ i:t~i~~ 1 4.95 1.50 ZS5195 74LS195 79.95 45.00 ( ZS5196 74LS196 59.95 29.95 ( ZS5241 74LS1241 39.95 22.95 } ZS5243 74LS243 12.95 2.50 { ZS5259 74LS259 6.50 1.00 ? ZS5366 74LS366 5.50 1.00 } ZS5854 7454 1 95 .40 ( ZZ8063 6845 CRT cont s:so 1.00 } ZZ8065 6850 .40 .10 } ZZ8080 MC1408L8 .50 .20 ) ZZ8082 8T-26A .40 .10 } ZZ81 95 81 LS95 .40 .10 ) ZZ81 98 81 LS98 .75 .25 1.00 .30 5.95 3.50 3.75 1.50 3.50 1.25 6.95 3.95 J '1f.m~g ELECTR ~t~g: ELE CTR ELECTR ~t~g~: m m • ELEC TF • ~ t~g~ • ELECTF • ELECTF • • ELE CTF • ELECTF • ELECTRONICS ELE CTRON ICS ELECTRONICS ELECTRONICS ELECTR ONICS JAYC AR JAYC AR JAYCAf1 JAYCAR JAYCAR ELECTRONICS ELECTRONICS ELECTRON ICS ELECTRONICS ELECTRONICS JAYCAR J AYCAR JAYCAR JAYCAR JAYCAR ELECTRON ICS ELECTRON ICS ELECTRONICS ELECTRONICS E LECTRONICS JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR ELECTRONICS ELEC TRO NICS ELECTRONICS ELECTRONICS ELECTRONICS JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR C!"'TOr"l ... llr'C' 11\'/,..,\0 C:I c:rTorv,urc: 1l!. V i"'l!.O i:: 1 i:: rTDr'l "-lfrC:: 1.l!.Vrl!.A i:1 Fr.TAnr..11r.c:. .IAVr.AA F I FrTR()Nlr..c:. .IAYr.AR F I Fr.TRnN1r.s .IAYC:AR ELECTRONICS ELECTRON IC& ELECTRON ICS ELECTRONIC S ELECTRONIC S FI FC:TRONJC:S ~c~g;; ~t~~i: Ew :n mw ~t~~;; men ,1.A.YC1~R E1. t: CTR0N iCS J,\\'CJ~R Ei.E:;TAONISS Jt .YC,\1-"1 ELE..CT:10NICS J, '1 YCI,:\ El.E:::Tr·.ONIC$ J i\' 1 C?F{ ELt:CTliCNF:S Jr'..··: Cf..~ EL~CTFl(;NI,>·. JAY·::An JAYCAR JAYCAR JAYCAR JAYCAR JA YCAR El r'. CTR E LECTR• ...... iliiilii tlt:Ll I H ELECTR ELE C TR ELE CTR ELE CTR 1: LEC TR [ LECTR ELECTR ELECTR· 29.95 16.95 17.95 42.50 139.00 139.00 46.95 34.95 12.95 9.95 10.00 79.50 139.50 269.00 639.00 1 v cAR ELI ,YCAR ELI J AYCAR J AYCAR J AYCAR Jt.YCAR ru.i, r c: ,,,v,....,,o r:• (::r'TrJf"'l i, i:r-c: 1,-.vr/\::J r.::t r-r T Qf'll\ll('C:: 1,~.vr6r-i 13.95 ) KC5044 Car safety lights 129.50 7: KC5048 Telephone bell monitor 45.00 ) KC5049 Aux brake light flasher 22.95 } KJ6502 Synthom drum synth kit 22.95 LT3182 91 element UHF ant 19.95 LA5019 PIR pulse count 39.95 LR8834 Car door actuator - heavy duty 15.95 • MF1030 PL 12/2DVA Ferguson T/F 19.95 )MA150660Dn/60Dn4KVT/T 13.95 MA1508 600.Q/60Dn arlec mini 24.95 MM1512 Modem transformer bargain 15.95 J MM2020 C Core T/F for 60/60 amp 12.95 { MT2170 Toroidal T/F 55/0/55 SOOVA 24.95 • MS4020 Mains filter - squeeky 4 outlet 29.95 ( Ml5010 600W inverter 240 12V ~g;~ it! ~~~rn ~::~~~ ~;:~~:~: ~~ ~:t ~:~:;~ vcAR ELI JAYCAR ELECTRONIC S JAYCAR ELECTRONICS JAYCAR.ELECTRONICS ,IAYCAR ELECTRONICS 26.95 6 Channel mic mixer 149.50 Motorcycle intercom 69.95 Book: Mac Program Tech 39.95 Book: Comp Aided Logic Design44.95 Book: Understand CAD/CAM 34.95 Book: Musical Applic-Micros 59:95 Book: IC Users Casebook 22.95 Book:AudiolCOPAmpApp 34.95 Book: 555 Timer Source 19.95 Book: Regulated Power Supplies 34.95 Book: Program and lnt 6800 29.95 Book: Micro for Business Applic 19.95 Book: Lotus 1-2-3 44.95 Book: IBM PC/XT User Man 47.95 ~g:: ~t: .•,HHGG99991112 BBi sshhoopp ggrraapphhiccss 2184 □0 1 L ppaatt teerrnn ~g:: ~t: ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS l!iilli■ll ,...,.......,...,,n ..... ••• ~~I~ rn :~AM4067 ~mrt~Tie:i~clasp~o;wiredf~~Imic:~~ spkr kit vcAR ELI r-T : JAYCAR JAYCAR JAYCAR JAYCAR llilliMI YCAR ELE v cAR ELI ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS - 1 ilillllM / CAR ELE / CAR ELE YCAR ELI ' "",...." ii■lii"4!1 /CAR ELE /CAR ELE vcAR ELI JAYCAR JAYCAR JAYCAR JAYCAR 1#.iif!WN!liill illli-.M!i~·--· /CAR ELE / C AR YCA R / C AR YCAR YCAR ELECTRONICS ELECTRONICS ELECTRONICS ELECTRO"ICS JAYCAR JAYCAR J AYCAR JA YCAR J AYC AR .I AYC: AR ELECTRONICS ELECTRONI C S l'LECTRONICS ELECTRONICS ELECTR ONICS Fl.FCTRONICS JAYCAR JAYCAR J AYCAR J AY CA R J AYCAR JAYCAR m en ELEt: TF ELE, :TF ~LE C..TF ELECTF ELECTF E'LECH ELEC Tf ELECTf FLE CTF AR AR .AR .AR ,AR AR AR AR AR AR AR AR AR AR AR ELECTRON ICS ELECTRON ICS ELECTRONICS ELECTRONICS ELECTRONICS ELECTR ELECTR ELECTR ELECTR ELECTR ELECTR ELECTR ELECTR ELECTR ELECTR ~=~~~g= AR AR AR AR AR AR AR AR AR AR AR AR AR AR AR AR AR AR ELECTR ELECTRC ELECTRC ELECTRC ELECTRC ELECTRC E:LE:CTRC ELECTRC ELECTRC ELECTRC ELECTRC ELECTRC ELECTRC ELECTRC ELECTRC ELECTRC ELECTRC ELECTRC . ·• ) : \ i ELECTRC ELECTRC ELECTRC ELECTRC ELECTRC ELECTRC ELECTRC ELECTRC ELECTRC ELECTRC ELECTR( ELECTRC ELECTR C ELECTRC ELECTRC ELECTRC ELECTRC ELECTRC ELECTRC ELECTRC ELECTRC ELECTRC ELECTRC ELECTRQ ELECTR( ELECTR( ELECTRG ~= ~~~gi=~ AR AR AR AR AR AR AR AR AR AR AR AR AR AR AR AR AR AR AR AR AR AR AR AR AR AR AR AR AR AR AR AR AR AR AR AR AR AR AR AR AR AR AR AR AR AR AR AR AR AR AR ELECTRON ICS ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR ELECTRONICS ELECTRONICS ELECTRONICS ELECTRON ICS ELECTRON ICS J AYCAR JAYCAR JAYCAR JAYCAR JAYCAR ELECTRON ICS ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR ELECT80NICS ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR ELECTRO NICS ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS JAYCAfl JAYCAR JAYCAR JAYCAR JAYCAR ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONIC,S JAYCAR JAYCAR JAYCAR J AYCAR JAYCAR ELECTRS ic ELECTRc · ELECTRC~:g ELECTRCIIIC ELECTRC AVAILABLE THIS MONT·H PROFESSIONAL RACK ENCLOSURES SENSATIONAL NEW RANGE OF PROFESSIONAL ELECTRONIC ENCLOSURES FOR 1991 In keeping with our promise to provide better and better products for you we are proud to announce a brand new range of melal cabinels thal otter oulslanding value for money In these laugh limes. These enclosures - all metal - are inlended primarily for professional/in"duslrial applications (because of their robustness and extremely high quality) but should not be out of lhe range of the pockel of lhe enthusiast who is looking for lhe ultimate in electronic cabinelry. The new range includes 19' EIA size rack enclosures built to professional standards and free standing bench lype melal cases. The quality is oulslanding. i i PRO GRADE 19" RACK STYLE EQUIPMENT ,,, i ENCLOSURE :: : i / ':; ::: :': ':: ) ~= ~~~gi=~ •• AR AR AR AR AR AR AR AR AR AR AR AR AR AR AR AR AR AR AR AR AR AR AR AR AR AR AR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR ., :, •. :' '' . Complies Wilh Standard IEC 297/F.IA RS-310 C-1977 / DIN 41494 Each cabinel is made from phosphated sleel and coaled wilh dark grey enamel. The colour malched rack Irani panel is in 3mm aluminium with exlruded handles. The rear panel is aluminium as well. The top, bottom and sides of each cabinet are liberally punched wilh ventilation holes. All screw fasteners are metal lhread - not self tappers. Top, bottom, front and rear of enclosures can be separately removed without attecting the integrity of the cabinel. Each enclosure comes with punched internal rail bars to facililale PCB, transformer, filler capacilor elc., mounling independent of cover panels. Each cabinet also features an internal sub panel (in 1.5mm enamelled aluminium which is adjustable from 0-20mm from the back of the front panel. This panel is ideal for mounling panel hardware (no screws need appear on front panel). Rear panel is also adjuslable 0-20mm inwards. The entire cabinet is packed flat for convenienl lransporl. Rubber mounting feet are provided. In keeping with the professional nalure of the product, an extended range of cabinet sizes are slacked. 1 UNIT ENCLOSURE Cat. HB-5120 2 UNIT ENCLOSURE Cat. HB-5125 3 UNIT ENCLOSURE Cat. HB-5130 4 UNIT ENCLOSURE Cat. HB-5135 5 UNIT ENCLOSURE Cat. HB-5140 $89 $109 $119 $139 $149 ELECTR( ELECTR( ELECTRC Dimensions in mm (all unils 482.6mm wide) ELECTRC .· 1U 2U 3U 4U SU ELECTRC . ELECTRC . "' _ .~111P Panel Heigh! 43.7 88.1 132.6 177 221.5 ELECTRC L ELECTRC Cabinet Heigh! 38.7 83.1 127.6 172 216.5 ELECTRC Cabinet Deplh 245 336 336 425 425 ELECTRC ELECTRC ELECTRC ELECTRC ELECTRC ELECTRC ELECTRC ELECTRC ELECTRC ELECTRC ELECTRC ' ELECTRC ELECTRC ·. ELECTR( . ELECTRC ~ ELECTRC ELECTRC ELECTRC ELECTRC ELECTRC ELECTRC ~ D ELECTRC This slurdy ni ckel plaled sleel 3 rack uml frame Is capable of accepting up lo 32 Eurocard slyle /_~ ELECTRC PCBs on a 1/2' (12 7mm) pIlch The depth can be adjusted lo accommodate cards from 160to ~ ~ ELECTRC 220mmlong Card heIghl Is also adjustable -down to under 40mm1 Either DIN PCB connectors orj iJ f,J J ELECTRC ELECTRC card edge conneclors can be mounled on lhe pre-punched adjustable backplane frame fj ' "' 1 ELECTRC A rack panel can be fItted via 4 x 3mm lhread hard prnnts on the frame This panel could be ELECTRC removed and replaced when frame Is installed in a rack as the frame mounls lo a rack _ 4 ELECTRC independentl yof a fronl panel Comes packed flat with all faslemng screws (metal thread) and olher "' ELECTRC hardware (no rear, top or boltomcove rs included) K "' ) ELECTRC II ELECTRC ELECTRC ELECTRC ELECTRC ELECTRO .'· ELECTRc5NI J C L CT N J Y• L , ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRON ICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS ,JAYCAR ELECTRONICS ELECTRO NICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRON ICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS \JAYCAR ELECTRONICS ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRON ICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRON ICS ELECTRONICS jAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS IJAYCAR ELECTRON ICS ELECTRONICS JAYCAR ELE CTRONICS JAYCAR ·ELECTRONICS JAYCAR ELE CTR ONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS J AYCAR ELECTRONICS 1\8....E.LECTRONICS ,JAYCAB FI ECTBGNICS IAYG'AB El ECIBONICS IAYCAB El ECTBON!CS IAYCAB El ECIBQNICS IAVCAB El FCIBQNICS IA~rAR El ECIBONICS I IAYCAB FI ECIBONICS ·!. 0 ... IEC 297 32 SLOT CARD FRAME (3U) -~B G ~ ~ B. J5) ""{<at> ~ JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR TRONI< ELECTRON!' ELECTRONH ELECTRON H ELECTRONI' ELECTROt-jl • JAYCAB FI FCIBON l 1 t li l \.,UoJl"'I I VM l l ' - ' - ' - ' - ' ' ' ''-' ' ~'.._,...,,_,,.,,,._,,,,, .._.._._,._, , , ,...., ,.,...., ..... ..,,,,...., ,., , - - - - • •• - • • • ~ - v , • · - · · • • - - - - • • - • · • - . . • _ , IC~ICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAfn IC~ICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELEC TRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS J AYCAfA l(~ICS JAYCAR ELEC TRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS J AYCAR ELECTRONICS JAYC AR ELECTRONICS JAYCAfA ,r~ICS~i~:!::S:e~~:B::!::=:8::~~~~:!::::ttl:~~:t!t~:!::=5:ij~ ::E~=l:tf:f:f:!::ij~iii ~til:1:±::; " ICS CS JJAYCAfA AYCAfA <!CS J AYCAf~ "CS JAYCAfA , !CS JAYCAfA ,1cs JAYCAfA, ,1cs JAYCAfA ,1cs JAYCAFA , 1cs JAYCAfA <!CS JAYCAfA ,1cs JAYCAFA Yes, the Metex M3650CR will interface with your computer via RS<!CS JAY CAIA 232. Connecting lead and software disk supplied. Monitor store and ,1cs JAYCAIA Function Range Resolution print out the output of the DMM on computer. It will take readings ,!CS JAYCAIA DC Voltage 200mV 100µV <!CS JAYC AIA over time and find and hold mimimum and maximum readings. 2V 1mV <!CS JAYCAIA 20V 10mV <!CS JAYC AIA , 1c s JAYCAIA 1 200V 100mV <!CS JAYCAIA 1000V 1V <!CS JAYCAIA AC Voltage 200mV 100µV ,!CS JAYCAIA 2V 1mV ;ics JAYCAI'\ 20V 10mV , ICS JAYCAIA <!CS JAYCAl'I 200V 100mV <!CS JAYCAl'I 750V 1V <!CS JAYCAl'I DC Current 2mA 1µ11 <!CS JAYCAI'\ 200mA 100µ11 ,ICS JAYCAl'I 20A 10mA l lCS JAYCAl'I l lCS J AYCA l'I AC Current 2mA 1µtl llCS JAYCAI'\ 200mA 1OOµtl llCS JAYCM 20A 10mA llCS JAYCM Resistance 2000 0.10 <ICS JAYCA"2kO 1n llCS JAYC AA 20kO 100 <ICSJAYC AA : <!CSJAYC AA 200kn 1000 .· ,ICS JAYCAA 2MO 1kO llCSJAYCM 20MO 10kn <ICS JAYCA~ Capacitance 2000pF 1pF . llCSJAYCM 200nF 100pF · ·JICSJAYCM JICSJAYCM 20µF 10µF JICSJAYCM Frequency 20kHz 10Hz JICSJAYCM 200kHz 100Hz JICSJAYCM Cal. OM-1450 JIGS JAYCM ICS J AY CM IICS J AYC A\ ICS JAYCA\ ICS J AYCA \ < ICS J AYCA \ JIGS JAYCA \ Youknowthescenario!Youbuyalewmetresolcableandbythelimeyou 64k CMOS ICS JAYCAI get round to using it, it's all messed up and ii takes you twice as long Hycasol is supplied in a bottle instead ICS JAYCA \ because hall the lime is spent on untangling it. It's not only frustrating- it E PROM of the usual environmentally unsound ICS JAYCA\ ICS JAYCA\ can damage the cable. Jaycar has now solved your problem 1 Our mosl Cat. ZZ-8465 spray can. II contains 500ml which is 2 ICS JAYCA\ popular cables are on small reels. 1/2 limes the amount ol lhe spray can. ICS JAYCA\ To use simply pour contents into a ICS JAYCAI JIGS JAYCAI glass or metal conlainer, brush on ICS JAYCA\ 14/0.14mm circuit board and return to bottle alter Cal. WB-1703 1 ICS ,IAYCA\ use. Can be re-used many times. PCB's 30 metre roll j ': ICS JAYCAI should be cleaned. Hycasol will NORMAL PRICE 30t metre · IICS JAYCA\ dissolve flux residues and grime leaving ICS JAY CA\ ICS JAYCA\ lhe track work and board absolutely ICS JAYCA\ clean. Sub C NiCads are commonly used in ICS JAYCAI Cat. NA-1050 2410.20mm battery packs to power RC racing cars ICS JAYCA\ 'ICS JAYCAI Cal. WB-1709 and cordless power tools. The most ICS JAYCAI 30 metre roll common voltage used is 7.2 volts which ICS JAYCA\ NORMAL PRICE 55t metre is made up with 6 x Sub C NiCads. Fix ICS JAYCAI your dud packs and save a fortune. The ICS JAYCAI Sub C's are suppl:ed with solder tab and ICS JAYCA< ICS JAYCA< are rated at ICS JAYCA, 1.2Ah. Cal WB-1999 ICS JAYCA, Cat. SB30 metre roll ICS JAYCA, 2456 ICS J AYCA, NORMAL PRICE 80t metre ICS J AYCA, ICS JAYCA, ICS JAYCA, Make your own printed circuil boards. Kit contains a 200 gramjar ICS JAYCA, ol Ferric Chloride, a dalo etching pen, a piece ol copper ciad board ICS JAYCA and inst ruclions. ICS JAYCA ICS JAYCA Cal. K.J -7900 ICS JAYCA I We are sick and tired ol paying too much tor reed relays through local suppliers, so ICS JAYCA we have done something about ii. These new ones are directly imported by Jaycar. ICS JAYCAI Check out the low prices. ICS JAYCA I ICS JAYCAI ICS JAYCA I CS JAYCAI ICS JAYCAI CS J AYCA I CS J AYCAI Cat. 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I CLEANING SOLVENT ETCHING KIT $13.95 _ -- _ . . . - -- - , . . .... . . . ......... .... , , ..., , ., , ............. .... , , ,...,, ~ ,...,..., ..,,.... , ...,,...., t ..... ... .... v, 1 IVl'UVU ..,,., I Vf"\ l l 1... 1..LV I nvr1uvo JM I L,l"\M CLCV I nVl'l/1\,.,.::, ,JMTVl"'ln C LC V I t"IUl'I CAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTBONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRON CAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRON CAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRON CAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS J AYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONI CS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTROM CAR ELECTR•l,ll,IW...W.lilooW..liloi;,;;;..w.101Mii,ii,,1,'-"..11,ii,,.....,;.a,-....,oW,M.,.a,ii1,ii-,,_.,QWw.li.W.lilooW....,..,.ii'-1WW.,ii,,1,'-"..11,ii--..,;ia,lllll,l"'"".w.M.,.a,ii1,iil,li,l-'IQWl.i.,.W1,lilooll,l;i,olil,i,..;ii"11~i.l.i-'..&.lii.li,l,fr:TROW :AR ELECTR :AR ELECTR :AR ELECTR :AR ELECTR ~AR ELECTR :AR ELECTR :AR ELECTR :AR ELECTR :AR ELECTR )AR ELECTR ByM CSharma )AR ELECTR )AR ELECTR Digital techniques are used in virtually every area ol Twenty six projects in all By MC Sharma )AR ELEC TR electronics. The greatest are included in this book. This book lirslly explains FET characteri stics, then MOSFETs )AR ELECTR use is in computers. The and on lo ampliliers using ··· ··· · They all use the SSS timer )AR ELECTR aim of this book is lo with some using lhe 556 FETs. II discusses )AR ELECTR ;AR ELECTR present in asimple and dual timer. Some projects oscillators, FETs as ;AR ELECTR practical manner the include: dice, head light switches, conslanl current :AR ~LECTR principles ol digital timer, all purpose timer, sources and voltage :AR ELECTR electronics. Chapter light llasher, siren, clock controlled resistors. 11 lhen :AR ELECTR headings include logic dimmer, voice operated :AR ELECTR describes 20 projects you :AR ELECTR circuits, flip llops, switch, low bal!ery alarm, can build using FETs and :AR ELECTR sequential circuits, minute lo 20 hour timer, MOSFETs. These include :AR ELECTR combinational circuits, capacitance meter, super preamps, amps, lone :AR ELECTR clocks and one shots and siren alarm, e!r., etc. control, oscillators, :AR ELECTR applications. :AR ELECTR 68 pages 140 x 210mm swi tches, voltmeters, VOX, :AR ELECTR 112pages 140x210mm Cal. BM -2436 clc. :AR ELECTR Cal. BM-2442 53 pages 137 x 212mm :AR ELECTR Cat. BM-2438 :AR ELECTR :AR ELECTR :AR ELECTR :AR ELECTR :AR ELECTR :AR ELECTR :AR ELECTR This book is awealth ol inlormalion, ideal tor hobbyists or :AR ELECTR anybody interested in winding their own lranslormers, Aller By P KAg(Jaf\.dl :AR ELECTR the introduction the book Thi s book has 15 projects :AR ELECTR covers all ribules ol By RO(JCr Walker lo build using ICs. The :AR ELECTR coils/lranslormers, mutual projects include: IC This llook descrillcs how :AR ELECTR •AR ELECTR inductance, reaclance, people use computers to regulated power supply, •AR ELECTR resonance, impedance, solve protilcms. staircase switch, electronic :AR ELECTR coil selectivity. 11 lhen Applir;alio11s arc discussed multiplier, touch switch, :AR ELECTR goes on lo lhe design and actual program sensitive doll, LEO !lasher, AR ELECTR aspects - discussing coils examples are provided. II electronic game, slop AR ELECTR AR ELECTR in tuning circuits, types ol watch, punlcs, quiz, magic you arc i;,lcrcslcd i11 the AR ELECTR lormcrs and cores, types switch, electricians liasic concepts ol ~ow a AR ELECTR ol winding, sell capacity, computer can he uscct lo companion, temp AR ELECTR equations, coil design, controlled oscillator, accompii sh parallel and AR ELECTR desi gn ol IF translormers revolving display. AR ELECTR serial communications, AR ELECTR then output and power nct.vork communications . 44 pages 140 x 210mm AR ELECTR lranslormcrs. Cal. BM-2434 lor modelling and AR ELECTR SS pages 137 x 21 2mm simulating systems and lo AR ELECTR produce graphics - this Cat. BM-2440 AR ELECTR AR ELECTR IJook is lor you AR ELECTR 284 pages 176 x 217mm AR ELECTR Cat. BM-2420 AR ELECTR AR ELECTR AR ELECTR By Russell & Dianne Slt,ilz AR ELECTR Explore the expanded lunclions ol lhis lull-lealurcd word AR ELECTR processing sollware using this book as your guide. Learn AR ELECTR By MC Sharma how to import graphics aml manipulate the new scalable AR ELECTR This boo~ does a great job ol introducing solid stal e lonls lo give all your documents lhal look. AR ELECTR electronics lo beginners, and then builil up thei r knowledge lo AR ELECTR Humlrccls ol illustrations By Don L Cannon . AR ELECTR a level where they can easi!y understand Ille clcsign ol and examples will have AR ELECTR Digital electronics continues lo lake over clcclrical, commercially available er,uipmcnl aml also clcsign their own lhc novice up and AR ELECTR mechanical and elect ro-mechanical system lunclions. circuits. Many diagrams help the reade r lo understand this in no lime. Expcricnr.cd AR ELECTR Maintenance ol digital systems - the need is · ra icll lascinaling sullject. Chapter headings include: users will lind this book ~R ELECTR as systems switch lo semiconductors, dioocs, ~R ELECTR an imlispcnsable rligilal clcclronics. Here is ~R ELECTR special purpose diodes, rclercnce tool. From ~R ELECTR an easy-lo-1111clcrslaml bipolar lcansislors. licld macro creation lo \R ELECTR lormal on Ille llasic ellccl transistors, basic automatic paragraph \R ELECTR principles and amplilicr circuits, styles, use this r,ompl cle \R ELECTR lrou l1leshooli11CJ transistor amplilier \R ELECTR rclcrc11ce lo master you r lecl1r1iq11es rcquirerl lo \R ELECTR design, voltage amplilicrs, worcl processing needs \R ELECTR IJC(J ill cl i(J ilal cnuipmcnl power ampliliers, video RF with Worcblar. IR ELECTR repai r anrl mainl cnam:c. aml IF amps, power 333 paqcs 153 x 224mm IR ELECTR Fu lly illuslralccl. lcleal tor supplies, oscillators, Cat. BM -2118 IR ELECTR scll-pacc1I imliviclual pulse circuit thyristors, IR ELECTR lca111ing. \R ELECTR oplo devices. \R ELECTR 266 paiJCS 176 x 217mm 296 pages 135 x 210mm ,R ELECTR Cal. BM -2422 Cal BM-2426 \R ELECTR ,R ELECTR ,R ELECTR INTO CASH!! ,R ELECTR ,R ELECTR Jaycar will purchase your swplus stocks ol components aml MORE N'E W BOOKS AND BARGAIN BOOKS FROM JAYCAR Further to our new range of books last month we now add another 17 new titles USING FIELD-EFFECT TRANSISTORS DIGITAL IC's $7.95 $3.95 FASCINATING IC PROJECTS UNDERSTANDING COMPUTER SCIENCE APPLICATIONS PRACTICAL TIMER CIRCUITS $3.95 UILD YOU ND TRAN s $3.95 $3.95 ONLY $12.95 SAVE $22 ILLUSTRATED WORDSTAR 6.0 TRANSISTORS AND THYRISTORS MADE EASY UNDERSTANDING DIGITAL TROUBLESHOOTING $29.95 ONLY $12.95 SAVE $22 $14.95 := ~t~gi= cq11 ip111c11I We arc co11ti11ually on lhc lookoul lor sources ol u_rimc c~r~li!Y mcrchanclisc. ,R ELECTR ,R ELECTR CALL MARK HARRIS OR BRUCE ROUTLEY NOW ON 02 747 2022 :=~t~gi= R ELECTR R R R R R R R 1991 CATALOGUE OUT NOW ■ ONLY$1.00 ELECTR:~;;:;:::;;;,::;;;:;:;:;::;::;:;;:;;:;:::;;;;,;:;;:;:;:;::;;;;;;:;;:;~~~;;;;;:;;;;;:;:;;;:;;;:;;;;;:;;;,;~;,;;;:;::;;;::;;::;;;;;;;;~~.;;;:;;;;;::;:;;;;;;;;:;;;;;:;:;:;:.;:;:;;::;;::;;;;:;;;::.:;;:;::;;;;::;::J ELECTR NI(.;::; JAYl'AH c U c(.;IHUNIG::; JAYGAH c LcGIHUNIC::; JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS IJAYCAR ELECTRONICS JAYCAR ELECTRONIC ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS IJAYCAR ELECTRONICS JAYCAR ELECTRONIC ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONIC'S JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONIC ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONIC ELECTRO NICS jAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS,JAYCAR ELECTRONICS JAYCAR ELECTRON IC ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRON'( A i:::: 1 i::::r" T A /'il\ill f"C IAVf"/\ D C l Cf"'TDl"'\'-llf"'C'.' IA\/f"'<AM c:- 1 r- r, T n,-,,,- u ,-,.,-.. '" =:l'IICS JAYCAR ELECTRONICS JAYCAR F NICS JAYCAR ELECTRONICS JAYCAR F- NICS JAYCAR ELECTRONICS JAYCAR FG'IICS JAYCAR ELECTRONICS JAYCAR ;; - ~w,. ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS JAYCAR JAYCAR JAYCAR JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ENHANCED MS/DOS BATCH FILE PROGRAMMING By M C Sharma The 741 OP amp IC is very inexpensive yet its comparable lo lhc besl in rcspecl ol versalil ily and superb pertormance We can't list every one of the 41 kils bul here is a lew examples: lnverling and non-inverting AC and DCamps, X'lal, magnetic, guilar, lelephone and mic prea mps, 3Wand 12W amps, inlercom, AC and DC molor control, schmill trigger. square wave gcncralor, !l ashe r, timer, light op relay, DC vollmeler. AC millivollmcler, RPM counter, A lo D converter, elc .. clc. 37 pages 140 x 21 0mm Cal. BM-2430 ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS JAYCAR JAYCAR JAYCAR JAYCAR 51 PROJECTS USING CD4011 By MC Sharma The CD4011 CMOS IC consists ol 4 NAND gales and can be put lo many applications The IC can be used as li near ampliliers, mu llivibralors, schmill trigge rs. pulse generalcrs and crystal oscillators. Some ol lhc projects include light ll ashers, blinkers, metronomes, burglar alarms, voltage indicators. timers and games. 45 pages 140 x 21 0mm Cal. BM-2432 $3.95 $3.95 RELAYS AND THEIR APPLICATIONS ESIGNIN TES.TING Y SPEAKER PROJECTS $49.95 BUILD YOUR OWN 80486 PC AND SAVE A BUNDLE By Aubrey Pilgrim This new book shows you how lo build you r very own DOS and OS/2 compal iblc 486 compulcr out of inexpensive third-party components and equipment ... no experience necessary! Find oul which sollware packages will best suil you r needs. and what business and personal !asks you can pertorm wilh your new home-bu ilt 486. You'll even find 011I how easy and inexpensive ii can be lo upgrade an older PC by installing new boards, displays, rt rives, and more. Nol only wiII you learn all you need lo know lo bui ld an 80486 machine. you'll gel a com plete course in micror:ompuler operalion lhal in ilsel l is worlh Ille price of the book. 220 pages 185 x 233mm Cal. BT-1 320 $34.95 Build your own low-cos! speaker syslcm lhal's as good. or belier than !he most expensive on lhe market? You can wilh !his 3rd edition book. Updaled lo rellccl the !ales ! lrcnds in audio technology, !his edition lcalurcs coverage ol:- • basic speaker lhcory • types and lunclions ol . speaker encl osu res • closed box and porlcd box speaker conslruction • crossover networks and tillers • PA syslems and musir.al insl rurnenl spkrs • speaker cquipmcn l sclcclion • speaker placemen! anrl acouslics • speaker lesling anrl lro11 lIlcshooling 21 4 pages 187 x 233mm Cal. BT-1 322 $34.95 Ca l. BM-2110 Cal. BM-2112 Cal. BM24 14 Cal. BM-2310 Cal. BM -2114 Cal. BM-211 6 Cal. BM-?.4 16 Cal. BM-4558 Cal. BM-4564 Cal. SM-4557 Cal. BM-2342 Cal. BM-2340 $16.95 $24 .50 $1 7.95 $29 95 $19.95 $24 50 $12.95 $14.95 $19.95 $9.95 $19.95 S1 9.95 . . ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR :J!/ii~~:~~.~~~~/{ I I ;~~ad~~ slale relays, relay . applicalions, ins!allalion, . adjuslmenl and lesling. . This is lhe lirsl book we've seen soley on relays. 112 pages 138 x 209mm • Cal. BM-2428 $9 " 95 ICS jAYCA Ics JAYCA JIGS JAYCA JIGS JAYCA JIGS JAYCA JIGS JAYCA ;:g~ 3:~g: IICS JAYCA IICS JAYCA IICS ,IAYCA ------ 1litiuku1,tt1idMS'll~i m~~ HOW TO BUILD A SMALL BUDGET RECORDING STUDIO By F Al lon Evcrcsl a111! Mike Shea Praclical yuirlancc in Ilic design, conslruclion a111I operalion ol you r own all orrlalilc acouslics sl11I1io. Every aspect ol designing a111I lmilrling an aurlio slurlio is lully rliscusserl: lloor plans. conlrol rooms, wall a111! ceiling lrcalmcnls, rcvcrliera'ion lime. air co11rlilioning, olIscrvalio11 wi1111ows. room proporli ons. acouslir.al lyrcalmenl . noise wIs!rleralions a111I more. II also shows you how lo:- • scl up alislc11ing room, a r-'corrting sl urlio, a conl rol room a11II ac:iicvc goorl sounrl • conlrol liackgrmmrl noise • make ar:011,lical nosurcmcnls 295 pages 184 x 233mm Ca!. BT- I324 $29.95 ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR Ics JAYCA JIGS JAYCA Ics JAYCA ;111 • · : DIS ):g! ~;~g; By Irving M Golll ic b A "liack-lo-liasics" guirlc lo design ing and l111ilil ing practical elect ronic lillcrs - lor engineers. technicians and hobliyisls. Using simple mal hcmalics and slraighllorwarrl proccrlurcs. Irving M Goll lich promo!cs a thorough unrlcrslanrling ol lillcr componcnls, inclurling how lo determine !hei r exact values arnl connccl !hem properly. You'l l learn common techniques tor laying 0111all(! assc mliling • low pass lillcrs • bandpass tillers • M..dcrivcd tille rs • crystal tille rs • high-pass tillers • band-rejection lillcrs • composite lillcrs • crossove r networks • a1111morr.I Most imporlanll y, you'll learn lhe dillcrenccs ticlwccn real-world a111I ·IcxllIook' lillcrs dsicovcring why tille r designers are so ollen led aslray by heavi ly mall1cn:alical lcxls - a111I how lo avoid lalling inlo Ilic same !rap with you r own tiller designs 185 pages 185 x 235mm Cal. BT-1326 ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS .JAYCAR ;:g~ ~:~g: i lCS JAYCA Ics JAYCA ;:g~ ~:~g: JIGS JAYCA ~;J:~:f~~~~~~e\~~ ;fililillll -lB.ll;!~i m~~ SIMPLIFIED PRACTICAL FILTER DESIGN . E't.ECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCA' ELECTRONICS JAYCA ELECTRONICS JAYCA ELECTRONICS JAYCA NICS JAYCA ICS JAYCA ICS JAYCA NICS JAYCA ~ICS JAYCA ~ICS JAYCA ~ICS JAYCA ~ICS JAYCA 'IICS JAYCA ICS JAYCA 'IICS JAYCA 'IICS JAYCA 'IICS JAYCA ICS JAYCA 'IICS JAYCA 'IICS JAYCA 'IICS JAYCA 'IICS JAYCA 'IICS JAYCA ICS JAYCA 'IICS JAYCA 'IICS JAYCA 'IICS JAYCA ICS JAYCA 'IICS JAYCA .ics JAYCA 'IICS JAYCA 'IICS JAYCA 'IICS JAYCA .ics JAYCA 'IICS JAYCA <ICS JAYCA <ICS JAYCA 'IICS JAYCA i lCS JAYCA By MC Sharma The aim ol lhis book is lo explain in a simple language, lhe variely, complexily, proper application , care a111I mai11lenance ol relays. This knowler.ge is also usc l11I tor selccling lhc righl relay lor a spcr.ilic job and lo gel a long lroulile-lree service lrom all lypes ol relays. Chapier heaIlings include: eleclromaynelic relays , relay J;). New and Bargain Books advertise d last month • full specs in those ads IONICS JAYCAR IONICS JAYCAR IONICS JAYCAR IONICS JAYCAR IONICS JAYCAR ION'CS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR 41 PROJECTS USING 741 IC By Dan Gookin Best selling book - supplied wilh sollware disk. Balch iiles are the lastesl. mosl reliable way tor you lo cul produclion timewhen pertorming sollware installations, ti le backups, or any olher repetitive computer chore. You can bui ld a versatile library ol balch tiles lhal lake lull advantage ol new DOS lealures. commercial balch tile exlenders. and uli ti lies lhal you write yoursell using C and Pascal. • Customise keyboard inpu l, cursor movcmcnl. menucs, and screen output • Simplily disk opcralion, tile manipulalion. and menu and screen conlrol • Make balch tiles in!o execulable tiles using the Builde r utility • Learn !he hidde n potential ol lhe eight major DOS balch file commands • Create your very own balch lang uage 336 pages plus 5 1/4" di sk Size 186 x 2 3 3 m m * Cal. BT-1318 MS DOS/PC DOS Quick Rclcrenr,e ll lusl ralcd Lolus 1-2-3 Release 22 Praclir.al Translorme r Design Book The Encycloperlia 01Electronic Ci rcuils Teach You rscl1 DOS 386 Compuicr Ha111llIook Understandi ng Digital Troulilcshooling Towers Digilal IC Sclcclor Towers lnl 'I Microprocessor Sclcclor Towers OPamp and Li near IC Sclcclor Scmicon·s lnrt Trans lnrlcx Data anr1 Equi Microprocessor Dala Handliook ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS JAYCAk JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR t:Lt:L I HUNIL~ JA YLAH ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR UCS JAYCA IICS JAYCA IICS JAYCA IICS JAYCA IICS JAYCA IIGS JAYCA IICS JAYCA IICS JAYCA IICS JAYCA IICS JAYCA IICS JAYCA ICS JAYCA ICS JAYCA ICS JAYCA ICS JAYCA ICS JAYCA ICS JAYCA ICS JAYCA ICS JAYCA ICS JAYCA, ICS JAYCAI ICS JAYCAI ICS JAYCAI ICS JAYCAI ICS JAYCAI ICS JAYCAI ICS JAYCAI ICS JAYCAI ICS JAYCAI CS JAYCAI CS JAYCAI CS JAYCAI CS JAYCAI CS JAYCAI CS JAYCAI CS JAYCAI CS JAYCAI CS JAYCAI CS JAYCAI CS JAYCAI tcLtce, 1HUN1CS JAYCAI ELECTRONICSJAYCAr ELECTRONICSJAYCAI ELECrRONICSJAYCAf ELECTRONICS JAYCAI ELECTRONICS !AYCAf ;;.A ELECTRQ~;cs jAYCAR ELECTRONICS jAYCAR ELECTRONiCS JAYCAR ELECTRONiCS JAYCAR ELECi-RONiCS JAYCAR ELECi-RONiCS jAvCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRc~; ;AA ;AR ;AR :AR :AR :AR :AR :AR :AR •: AR :; AR •: AR •:AR : AR :: AR ::AR : AA : AR : AR ::AR ::AR :: AR ::AA ::AA ::AR <AR <AR <AR <AR '.AR '. AA : AR : AR : AR : AR :AR : AR '. AR '. AR '. AR : AR '. AR '. AR · AR : AR :,AR AR , AR .,AR ELECTRONICS JAYCAA ELECTRONICS JAYCAA ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTR~I ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS J AYCAR ELECTRONICS JAYCAR ELECTR½-11 ELECTRl~ll.ii~~~~~~~~~~~~~~~~~.ii.liil..lil~~IM.,liu,Q,.,.;,~W~lii,sl,~oi,,,J,l,;i/,.AliW~;.a.~;,;l,,~.;.:l,ll.-'iW.i;j;W~U.fl.i..e.ll.W~,W;l,W..:l,Ji,(l:i;:~~CTR~1 ELECTR1I ELECTR< ELECTR1 ELECTR1 ELECTR1 ELECTR1 ELECTR1 ELECTR1 ELECTR 1 ELECTR< ELECTR1 ELECTR< ELECTRI ELECTA< ELECTA< ELECTR1 ELECTR1 ELECTRI ELECTRI ELECTR1 ELECTR1 ELECTR< ELECTR< ELECTR1 ELECTAI ELECTR1 ELECTA1 ELECTR< ELECTR1 ELECTR< ELECTR1 ELECTR 1 ELECTR1 ELECTR1 ELECTR1 ELECTR1 ELECTR• ELECTR ELECTR• ELECTR• ELECTR ELECTR ELECTR· ELECTR ELECTR ELECTR ;rR ; rR ;rR ,f,R ,f'.R , f-.R ,f'.R 1f'.R , f'.R , f'.R , f'.R ,f'R if'R i f' A , f'A , flA , FIA , flR , flR ,pR ,pR 1pR ,f;IR 1f;1R ,Jt,R ,f1'R ,ft-R •R'R <AIR 'R'R •R'R ,R,R '13.'R ~~~g;=: ELECTR< ELECTR< ELECTR< ELECTR< ELECTR< ELECTR< ELECTR< ELECTR< ELECTR< ELECTR< ELECTR< ELECTR< ELECTR< ELECTR< ELECTR< ELECTR< ELECTR< ELECTR< ELECTR< ELECTR< ELECTR< ELECTR< ELECTR< ELECTR< ELECTR< Al last a tow cost quality, portable butane powered !tame torch. Ideal !or the hobbyist and professional. Adjusfable!lame, complelely portable, up lo 90 minutes use per !ill, adjustable temperature control, mini size, uses standard butane oas li ghter fuel. Ideal for shrinking hea lsh rink lubing. Cal.,TS-1410 ONLY $12.95 DC SOLDERING OPTION Cat. TS-1412 Fluoro Inverter Kit Ref: Silicon Chip Feb 1991 This kit enab les you to build a high power inverter suitable for driving a 20 watt fluorescent light from a 12V car battery. Short form kit. Sec catal ogue for full details. Cat. KC-5091 $9.95 ONLY $8.95 SAVE $4 $32.95 STEAM SOUND SIMULATOR KIT FOR RAILMASTER TRAIN CONTROLLER INTELLIGENT GEL BATTERY CHARGER BARGAIN Wehave a limited quanti ty of these quality chargers availat1le. They are 240V ope rated with an oulput ot 14.2V al 1.6A max. II is an inlelligenl charger, wh ich means !hat when fhe ball ery is charged lhe unit will autom atica ll y swi tch itself to tri ckle cha rue saving damage to the batlery 21111 charger Most Get chargers 1lo!i'I have this feature ii will 1.naroc our 5.SAh tiatlcries i11 about 10 hours an11ou r 15Ah cells :n atioul 20 hou rs. Outpul load lo t1alie ry is a 3 pi n Carmon type wl1ich in most r.;iscs will need lo be removed. Mains leail lonol h 2 moires, oulput leail lcnglh 1.8 melres. Si1e t75(L) x 115(W) x 60(H)mm. Cal. MB-3507 SAA APPROVED Rei Silicon Chip April 1991 Had enough ol thal silly whine coming out ol your HO-scale '38" loco? This sleam sound si m,,tator makes a reali stic "chulling· sound that keeps pace with the loco speed. Kil includes PC board al l specilied components and !he expensive 82mm loudspeaker Cat. KC-5093 AN ABSOLUTE BARGAIN AT $69.95 it ~J.i .~ {... ,.. '~ ~~~ "*•· ,.\ .#/: · .,, PHILIPS MICROPHONE BARGAIN ~; " _;fl'- ,,_. -~ We had a quantify ol these some lime ago, a11d we still get aske1f ii we have any more availat1te. They are 11sed in televisions. They have roll su rroumls a111I are QUALITY small speakers. TYPE 1 NOW ONLY $19.95 SAVE AN AMAZING $40 Oval speaker. rubber roll surround. Size: length 68mm. width 34mm, heiglil 33rmn. Impedance 7n. Power handling 1 wall. Cal. AS-3020 $3.95 TYPE 2 CRO ADAPTOR KIT QUAD 'DI' BOX KIT Rei EA Ju ne 1991 Thi s simple kit wil l ,eplacelour separate 1lirecl injeclion (DI ) txms. 11111at a lroclion ol llJCi r lol"l cost. II oilers excel lent perlor111ance a111J,s ideal lor co11necli11g a t1a nk ol musical i11slri11w:11l•; to a sla 111lanl mixi ng 1lcsk. T!1e J;1;car kil i11cl111lcs PCB. i11slrumcnl case. ca1111on type cc,rir,ecrors pl1or10 skis anil all spec,tir:11 eu111pown1s to CDITlt:lele the fHC1J[;Cl Cal. ~A-1734 $79.95 -t!llfii, SMALL- SPEAKERS IA Phil ips list price $59 95 '$~ .. Railmasler Trai n Conlroller kit Cal. KC-5028 $89. See catalogue for lull details. Don·1 r11iss !his onc 1 ll's a higl1 quality stereo conrlcnser cieclrel micropl1one. Phili ps came to Jaycar to clear their excess slock. Thei r lisl price !or !his unit is S59 9511 1 Features incl111le·• Uni-1lirecliona l polar pallern • Des igne1t in wi111ls hie l1I lor ilislorlion lree sound • For slu1lio aml home recorclmg • Tat1lc stan1l a1111 vinyl carrying case inctu1Je11 Spccilicalions Freq uency Range 50-18,000H! lmpo,1a111:e Goon Scnsil1v,1y 471l8 ±3118 Connec tor 6.Smrn plug Aila plor 6 5 lo 3.5mm supplic1I Coril Le ngth 3 metres 1.SV AA require1t Ballery Suppl y Cal AM4085 ,;,- -'~~;;~-=~"" ,, $2495 ::AR ELECTR ,AR ELECTR ,AR ELECTR AR ELECTR 1 ,AR ELECTR AR ELECTR 1 ,AR ELECTR 1AR ELECTR 1AR ELECTR< 1AR ELEC TR• 1AR ELECTR 1 1AR ELECTR• 1AR ELECTR• 1AR ELECTR, 1AR ELECTR 1 ,AR ELECTR, ,AR ELECTR1 pAR ELECTR• pAR ELECTR1 pAR ELECTR 1 fl',R ELECTR, t,A R ELECTR1 rf,R ELECTR1 AAR ELECTR1 AAR ELECTR< ._A.R ELECTR1 ._AR ELECTR< ._AR ELECTR1 ._A.R ELECTR< ._AR ELECTR< A.AR ELECTR< A"-R ELECTR< ~~= BUTANE MINI TOOL We recen tly received a delivery of speakers irom our overseas suppli ers. They were supposed to be Cat. CE-2320 6" round twincone widerange. We received 5· sing le cone 10 watt wide range in the pin cushion frame style, as our AS-3012 is. These speakers are worth $13.95 less $1 for no twin cone - so let's say S12.95. You can purchase these for the crazy price of on ly $8.95 each. Saving you S4 off the usual price. Cat. AS-3012 Rei EA March/June 1991 This project is a fully lealured oscilloscof'I) Iha! uses a lowcost co11ve11lional computer rno11itor as the llisplay. It's not you r ave rage CRO adaptor eillier! II can display wavelorms ol ove r 1MH1. can meas ure DC volt s, (not display, aclually measure). me asure lrcq uc11cy and peak lo peak vollage and il's a storage CRO ' TIieJaycar kil i11cl 11,fes 3 PC t1oants, mains lranslorme r, IC sockets. swilclies. sockets . knot1s anil all specified compo11c 11ls. No t1ox supplied. Cal. KA-1735 $179.50 Oval speaker, but wit h 4 holes !or standa:d type mounling. Roll surround. Si1e: length 70mm, wi1llh 40mm , he igh! 29111m. l111pe1lance 12Q Power handli ng 3 walls. Cal AS-3021 $3.95 TYPE 3 Oval speaker with 4 holes for mounling Same dime nsions as lype 2. Impedance SQ. Power handling 5 walls. Cal AS-3022 $5.95 TYPE 4 Smal l round speaker wi th an impe1lance ol soon Cou ld poss ihty be usc11 as a small a11don tweeter !or ra1lio or TV elc. 40mm iliameter. Mounlino holes are 47mm apart. Depth 13mm. Cal.AS-3024 $1.95 ELECTR<b~:;;;:;;;;~;:;:=~~~~~~~~~:;;;:;;;:~~.;;;;;:::;:;:::;:::;:;:;:;;:::;;;;;:::;;;=.:::;:;:;:;::;;;~~~~;:;;:::;:::;:;::;;;;:::::;;:::::;;::::;::;::;:::;;::::::::===::::~J JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS IJAYCAR ELECTRONICS JAYCAA ELEcCTR ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAA ELECT.RONICS ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS JAYCAR J AYCAR JAYCAR JAYCAR JAYCAR JAYCAR ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR ELECTRONICS ,JAYCAR ELECTRONICS iJAYCAR ELECTRONICS JAYCAR ELECTRONICSIJAYCAR ELECTRONICS JAYCAR ELECTRONICS 'JAYCAR ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR ELECTR ELECTR ELECTR ELECTR ELECTR ELECTR I( IC IC IC I( IC < CS JAYCAR CS JAYCAR IC$ JAYCAR ICS _JAYCAR ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS .. .. ...· ..·.• J AYCAR ELECTRONICS JAYCAR ELECTRONICS JAYC AR ELECTRONICS JAYCAR ELECTRONICS ...... ·.·.•.·.· .. .·.·.·.·.· .. ·....·.. ·:·.·.·.. ·.·.·.·. JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS J AYCAR ELECTRONICS JAYCAR JAYCAR ELECTRON ICS JAYCAR ELECTRONICS JAYCAR ELECTRON ICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS ,JAYCAR JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYC AR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR JAYQl\fll=IJ'.QJJ\Q!'/IQS, ~~;,'.\;l\flc~i=QJ~Ql)llQS, ,l~;,'.1,1\FJc~,Ey;J;F'Q/)llQS, ,l~X\il}f1./;\-FyJfjQtJ19~ ,yt\Wb~.E.l,E\:J.f'jQ,t-J19S, }!',Y9~~ .. .. . .. ROFESSIONAL BENCH ENCLOSURES Great new range • Are you sick of buying a so-called 'professional' box only lo find you STILL have to drill !he mounting holes for the lid? • This new rangeof bench cabinels features prfe-punched • venlilation holes, metal thread faslening screws, aluminium • pre-painled front and rear panels, up lo the minute styling, • facilities to mount internal hardwarewithout recourse to • drilling lids - and great prices! • Apart from lhis, the enclosure fealure cabinet heights that comply with standard IEC297 rack heights. Even though they are not rack cabinets many components (especially transformers) are made lo comply lo these height dimensions. This slandardisalion is a good thing. Cal. HB-5550 88.1(H) x 177(D) x 203(W)mm $34.95 THROMATIC SECURITY SENSOR This great product utilises a passive inira red detector which controls 240V lights to ill uminate al nigh! when a person comes within range. A typical examplewould beon a verandah. When someonewallks within range (up to 15m away) the verandah Is Ill upfor a period of 5 seconds to 10 minutes, or more. Suitable for entrances, porches, patios, stairways, garages, attics, basemenls, hallways, close ts, showrooms, ware houses, workshops, etc. WAS $69.50 SAVE $30 over previous models $44.95 • $44.95 Cal. HB-5570 132.6(H) x 279(D) x 304(W)mm $54.95 ICONDUCTOR PACK Available once again Pack contains 100 pieces. May include transistors, diodes, IC's, computer chips, RAM, TTL, CMOS, etc. We cannot guarantee that all items above will be included but we can guarantee at least 100 brand new prime spec sem is and $1O will represe nt an absolute bargain. $1,-. Cal ZP-8990 • . <at>_: '' r d ( ' Ideal for students or anybody who wants lo learn about solar energy. This ki t shows you how lo make a solar syste m. • make a solar circuil • make an electrical ci rcuit Cat. KJ-6692 • learn how to increase vol tage • learn how to increase current • learn how to make a solar panel • use solar power lo produce energy for a radio, calcu lator, ballery charger and 1.5V casse lle player. The kit includes 8 solar cells, which fit into a plastic housing and can be connected up in either series and parallel, a molor and mounling bracket, a fan, tool for connecting solar cells and a1opage bookie! explaining lhe why's and how's of solar energy. $24.95 • LOWER PRICES ON HIGH BRIGHTNESS LED's all 5mm round styles 500mCd RED WATER CLEAR cat.ZD-1792 NOW ONLY 1OOOmCd RED WATER CLEAR cat. ZD-1793 NOW ONLY $1 ea 140 walls rms per channel. See calalogue for lull delails. Cat. KA-1725 $599 $2 ea 3000mCd RED WATER CLEAR cat. ZD-1796 NOW ONLY $3.25 ea 160mCd YELLOW WATER CLEAR Cal.ZD-1795NOW ONLY BOmCd GREEN WATER CLEAR cat. ZD-1794 ICS ICS ICS IC$ ICS !CS 1r. so~ ea NOW ONLY SO~ ea JAYCAR ELECTRONICS JAYC AR ELECTRON ICS JAYC AR ELECTRONICS JAYC AR ELECTRONICS JAYCA R ELECTRONICS JA'l'C.ABJ:LECTBONICS JAY CAR JAYC AR JAYCAR JAYCAR JAYCAR JAYCAR ELECTRONICS ELECTRONICS ELE CTRONICS ELECTRONICS ELECTRONICS ELECTRONICS JAYCAR JAYCAR ELECTRONICS JAYCAR JAYCAR ELECTRON ICS JAYCAR J AYCAR ELECTRONICS JAYCAR JAYCAR ELECTRONICS J AYCAR JAYCAR ELECTRONICS JAYCAR J,;_Y~R_f:LECTRONIC S JAYCAR Catalogue price ( 1990) $169.50 SAVE42% ONLY $99.50 JUNE BARGAIN ONLY $49.50 . Cal. HB-5565 132.6(H) x 279(D) x,203(W)mm AST CHANCE METEX TRUE rms AUTORANGE DMM WAS $169.50 Cal. LA-5129 Cal. HB-5555 88.1(H) x 279(D) x 304(W)mm ELECTRONICS JAYCAA ELECTRONICS JAYCAR ELECTRONICS JAYCAF E_LECTRONICS JAYCAF NICS JAYCAR ICS JAYCAF ~ICS JAYCAF ICS JAYCAF ~ICS JAYCAF ~ICS JAYCAF ~ICS JAYCAF ~ICS JAYCAF . ¼1cs JAYCAF ¼ICS JAYCAF ~ICS JAYCAF ~ICS JAYCAF ¼1cs JAYCAF ¼1cs JAYCAF ¼1cs JAYCAF ¼1cs JAYC AF • ~ICS JAYCAF Runout sale. We've • \JIGS JAYCAF only asmall quantity .• ~ICS JAYCAF left. . ;-JIGS JAYCAF \JIGS JAYCAF Cal. OM-1500 . \JIGS JAYCAF . \JIGS JAYCAF .. ~ICS JAYCAF \JICS JAYCAF \JIGS JAYCAF \JIGS JAYCAF ;-JIGS JAYCAF ;-JIGS JAYCAF \JIGS JAYCAF NICS JAYCAF NICS JAYCAF NICS JAYCAF NICS JAYCAF NICS JAYCAF NICS JAYCAF NICS JAYCAF NICS JAYCAF NICS JAYCAI NICS JAYCAI NICS JAYCAI NICS JAYCAI NICS JAYCAI NICS JAYCAI NICS JAYCAI This book lakes you through the creative possibilities of the NICS JAYCAI PC and acls as a guide lo the twin minefields of choosing NICS JAYCAI software and hardware for making music. This book also• NICS JAYCAI explai ns lhe basics of compuler music• explains NICS JAYCAI NICS JAYCAI sequencing, sampling NICS JAYCAI and nolation • NICS jAYCAI checklisls for software NICS JAYCAI and hardware • shows NICS JAYCAI where lhe PC fils inlo NICS JAYCAI Nies JAYCAI the studio • full of . ICSJAYCAI practical lips on Nies JAYCAI equipmenl etc. • ICS JAYCAI guidelines for NICS JAYCAI programming music ICS JAYCAI NICS ,IAYCA applications• Nies JAYCAI appendices on MIDI, ' ICS J AYCA communications ICS JAYCA conlacls NICS JAYCA 160 pages 216 x 138mm ICS JAYCA Cat. BP-1226 NICS JAYCA NICS JAYC A NICS J AYCA NICS JAYCA NIGS JAYCA NICS JAYCA NICS JAYCA 11 NICS JAYCA NICS J AYCA NICS J AYCA If you want somelhing belier lhan acone tweeter try this NICS JAYCA dome. Replace those ageing twecler and give your speakers NICS JAYCA some new life at the lop end NICS JAYCA SPECIFICATIONS NICS JAYCA Impedance Bn NICS JAYCA NICS J AYCA Max Power 20W (75W system power) NICS JAYCA Resonant Freq 250GHz max NICS JAYCA Frequency Res 3000 - 20,000Hz NICS JAYCA Sensitivity 94dB 1W/1m NICS J AYCA Cal CT-2008 NICS JAYCA NICS JAYCA NORMALLY $14.95 NICS JAYCA NICS JAYCA NICS JAYCA NICS JAYCA NICS JAYCA NICS JAYCA NICS JAYCA NICS JAYCA NICS JAYCA NICS JAYCA \JICS JAYCA \J IGS JAYCA \J IGS JAYCA \JICS JAYCA ~ICS JAYCA \JIGS JAYCA \JIGS J AYCA JA C R ELE TR NIC JAY AR EL NICS NICSJAYCA JAYCAR ELECTRONICS JAYCAR ELECTRONICS J AYCAR ELECTRONICSJAYCA JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCA JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCA JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCA JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICSJAYCA JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICSJAYCA ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS ELECTRON ICS ELECTRONICS ELECTRONICS THE PC MUSIC HANDBOOK for IBM PCs and COMPATIBLES $22.95 3 " TWEETER (1 DOME) JUNE SPECIAL $9.95 SAVE $5 BOOKSHELF Assembly language for 386 computers 80386 Assembly Language - A Complete Tutorial & Subroutine Library, by Penn Brumm & Don Brumm. First edition 1988, published by Tab Books Inc, Blue Ridge Summit, PA, USA. Soft covers, 234 x 189mm, 626 pages. ISBN 0-8306-9347-5. Price $59.95. Before we start, .we must say that this book is only for the serious programmer who knows which end of his keyboard is up. It assumes that you have already done some assembly language programming using MSDOS and also that you understand how assembly language works. But with that in mind, it is a goldmine of information and a must for anyone who wants to program for a 386 machine. The book starts off by introducing the topic of "efficient programming", a few of the things that should and shouldn't be done and an overview of program design. There's a chapter on Reference on VHF-UHF techniques VHF-UHF Manual, edited by G. R. Jessop, G6JP. 4th edition published 1983 by the Radio Society of Great Britain. Soft covers, 184 x 184mm, 505 pages. ISBN-0-9006 12-63-0. Price $48.00. This is an oldie but a goodie. Now in its fourth reprinting, this book has been a noted reference text on RF reception for amateur radio operators for many years although much of what it contains can also be applied to the wider VHF/UHF scene, including scanners and TV reception. With over 500 pages and 11 chapters, the text goes into the subject material in considerable depth and for the most part, mathematical descriptions are avoided - it is "' 81381 ASSEMBlY LANGUAGE Peon Br..inlln ard Don Brumm using MS-DOS more efficiently, too. Chapter 3 moves onto programming the 386, noting such things as registers, privileges and protection, debugging and testing. Chapter 4 contains a number of useful assembly language procedures, including one that subtracts and adds 63-bit numbers. Chapters 5 through 7 talk about interrupts and masking, as well as bit and string manipulation and 32-bit code conversion. G. R. JESSOP, GGJP FOURTH EDITION strictly a practical text although there is a good portion of theory included. There are quite a few practical circuits presented too although some of these, involving valves, are now getting a little long in the tooth. And as you might The topic of the 386's I/O port is discussed in chapter 8 which also describes how to read and write from files . Some well-known algorithms, including shell and binary sort are laid out in chapter 9, including program examples. · Elementary graphics programs are provided in chapter 10 which also briefly mentions the character matrix. More technical information is provided in the appendices, including an architecture overview and informadon on the registers , flags and bits in appendices A and B. Appendices C and D give the complete 386 and 387 instruction set, appendix E the ASCII characters and keyboard codes, appendix Fan overview ofOS/2, appendix G an overview of BIOS/MS-DOS interrupts and calls, and appendix H debugging tools. All in all, this is a book well worth the cover price and definitely worth having as a reference work. Our copy came from Jaycar Electronics and sells for $59.95. (D.Y.) expect, with a publication date of 1983 for the 4th edition, it does not feature many modern ICs that are now very commonplace. The 11 chapter titles are as fol lows: 1. Historical Perspectives; 2. Propagation; 3. Tuned Circuits; 4. Receivers; 5. Transmitters; 6. Integrated Equipment; 7. Filters; 8. Antennas; 9. Microwaves; 10. Space Communications; and 11. Test Equipment. We don't have space to go through the contents in any detail but we can highly recommend this text if you have any involvement or interest in radio communications. Our sample copy came from Stewart Electronic Components, 44 Stafford Street, Huntingdale, Victoria 3166. Phone (03) 543 3733. (L.D.S.) JUNE 1991 53 SERVICEMAN'S LOG Whistles aren't always carefree As a kid, I had quite a repertoire of whistles. I could whistle on a gum leaf, I could whistle through my teeth, and I could whistle through my hands. Unfortunately, not all whistles bring such simple pleasure. critical, due to standing waves in a room and the disposition of furniture and curtains. In addition, the actual level itself can vary due to temperature changes and other factors. All of which can easily add up to situation where a customer can hear it and a salesman, or serviceman, cannot. It's not so bad if the salesman or serviceman knows that this can happen. But if he doesn't, it can lead to serious misunderstandings and to a totally dissatisfied customer. More about that later. In this case, the set belonged to a young couple, was about one year old, and was still under warranty. The wife rang me and complained about an "annoying noise" coming from the set but without much indication as to the nature of the noise. This was important because I had recently had a similar complaint about the same model set, which turned out to be a noisy power transformer. And I do mean noisy ; it c ould be ' 1: I heard in the next room. It was obviously due to loose laminations but there was little I could do to tighten them. The transformer I is enclosed in a steel . . case, so I simply replaced it under war-.,.,---::-;:_-:::-· ) ranty. .::------_ I After some questionCf-,_:),r1'1 v§r-.". ing on my part as to whether it was a high pitched or low pitched I CP.Rf:FUl-L'-f ?OS I'll ONW sound, and a consulM'-f GOOD E:.P..'R ••. _ And that's the theme of my main story this month. It is about a Samsung colour TV set, a 34cm model (type CB336H), and a fault which is now relatively rare. It was not always so. In the early days of TV, it was a common problem which plagued many a salesman and, in some cases, lost sales. I'm talking, of course, about the high pitched 15,625Hz whistle which emanated from the horizontal output transformer. This whistle was caused by the magnetostriction effect; ie, the physical distortion of the transformer core due to the magnetic field. One problem with this fault is that there are a number of variables which can make it difficult to pin down. Not everyone can hear frequencies this high. In general, young people are more sensitive to it than older people, and women more so than men. The listening position can also be ~~ ex~ it L 51 --- ~nr-z 54 SILICON CHIP tation with her husband, she replied that it was high pitched. And it then transpired that, contrary to the usual rules, it was the husband who found it most annoying, while his wife could hear it only occasionally. I advised her to bring the set in. In the event, there was someone else who had difficulty hearing it yours truly. Age has taken its toll and these tired old ears have not had much to do with that part of the spectrum for some time now. That's not to say that I am totally unaware of the problem, if it exists. I can hear something but I doubt ifit is at 15,625Hz. I think it is more likely that there are some lower frequency components present - sub-harmonics if you like - and they serve the purpose. Initial checks Anyway, when the set arrived I plugged it in and made a preliminary check. Initially, none ofus could hear anything. Then the husband said he could hear it faintly but his wife could not, and neither could I. Then, according to the husband, it vanished but then re-appeared again a few minutes later. I suggested they leave it with me. Later, when I had (literally) a quiet moment, I pulled the back off the set, plugged it in, and let it run for about half an hour. This, according to the husband, was when the whistle was most likely to appear. I then positioned my best ear as close as safely possible to the horizontal transformer. And yes, I could sense something. More importantly, by probing around the area near the transformer, I could make it come and go. So, there seemed little doubt that this was the offender. Nor was there any doubt as to the cure; a new transformer. I've never encountered any satisfactory repair technique for this fault. In any case, the set was under warranty. So a new transformer was ordered, duly arrived and was fitted to the set So what did that leave? As far as I could see, only the side pincushion transformer, T402, which is effectively in series with the deflection coils. My suspicions were further aroused by the fact that this transformer sits close alongside the horizontal output transformer; so close , in fact, as to make it difficult to differentiate between the two on an audible basis. On the other hand, if this was the culprit, it also would be a first in my experience. And that left me wondering ifl could risk replacing it on spec, having already made one mistake with the horizontal output transformer. Technical help And that did seem to fix it. I certainly couldn't hear anything, nor could the husband when he came in to check it at my request. So he tucked the set under his arm and went on his way. Sam still whistles All was quiet - at my end, anyway for about a week. Then the lady was back on the phone. All was not so quiet at her end; the fault was back. As she described it, "the set still does it a bit", although it was not nearly as bad as before. But they were worried that it might get worse. Privately, I was worried too, but suggested that they try it out for a couple more weeks and see what happened. What I really wanted was for it to become bad enough so that there could be no doubts about the problem. And that's more or less what happened. Several weeks went by and then the lady was on the phone again. It was now much worse; in fact, according to her husband, it was as bad as it was originally. So I said, "bring it in and we'll have another look at it". It didn't take me long to confirm their observations, which put me in a bit of a quandary. If it wasn't the horizontal output transformer (two dud units in a row would be too much of a coincidence), then what was it? The diagnosis boiled down to nominating all those components which handled this frequency, then considering each in turn and questioning whether it could be the culprit. My first suspect - but one which I discounted almost immediately - was the horizontal driver transformer, T401. Granted, it handled this frequency but at much too low a level to be a serious candidate. At the other end of the chain was the horizontal deflection coil assembly. Well, there was plenty of energy there but, ifit was the culprit, it would be a first in my experience. In any case, the location was wrong. Even with my limited hearing, I could not reconcile what I heard with these coils; the source was somewhere on the board , near the horizontal output transformer. Finally, I decided to play it safe and tackle the Samsung service department with the problem and my theory. So I rang them and asked for one the technicians who has proved to be helpful in the past. And even while I was describing the problem, I had a feeling that he was way ahead of me. When I eventually asked if my diagnosis was correct, his reply was immediate: "that is the problem. We've had a few of these, but only on the chassis fitted to that model set". (He was alluding to the fact that the same chassis is used in several models, of different sizes and with varying refinements). Just why the fault should occur in only this model is not clear. My tip is that this pincushion transformer is different, either by design or, more likely, nominally the same but from a different manufacturer or even from a different batch. Anyway, that was the solution. A new transformer arrived a couple of days later, I fitted it, and could detect no sign of the trouble. More importantly, neither could the customer, in spite of prolonged observation before he took it away. That was several weeks ago now and, at a recent check, everything is quiet. So make a note of that one and don't write off a customer's complaint just because you can't hear it. The bush serviceman This brings me to the point I made earlier, about sales being lost because TV salesmen did not always understand the problem. It reminded me of an actual incident , in the early days of TV, in which I was involved. It was shortly after TV had started, JUNE 1991 55 SERVICEMAN'S LOG - CTD at a time when the first country services - one commercial station and the ABC - were being set up. At that time , I worked for a sales/service organisation in a large country town. My role was primarily that of a serviceman but there was always the opportunity for a spot of sales work on the side. The reward was a modest but worthwhile commission; a very welcome addition to the regular pay packet. I had scored a few such sales but one family that I had set my sights on were proving hard nuts to crack. They were a nice couple, long standing customers of the firm, and I had come to know them well on the basis of various radio and other appliance repairs. But the expense of a TV set was not something they were prepared to rush into. Against that background, my sales pitch was too much of a soft-sell. It often amounted to nothing more than a half joking, "when are you going to buy that TV set?", which invariably prompted a similarly lighthearted re- OYNAPULSFm 2QOM The DYNAPULSE 200M is an innovative and superior method of monitoring and recording vital personal health information. In conjunction with your PC this unit allows you to measure and map your blood pressure and pulse accurately, as well as printing, graphically displaying and storing your data for later comparisons. PEACE OF MIND FOR: $397.00 ply, "aw, someday". It became a ritual that went on for several months. Then one day, returning from a service job out in the bush, I passed their house on the outskirts of town. They were both in the garden and waved cordially when they saw me. Somehow I sensed it might be a good time to stop and have a yarn - a popular pastime in the country. It was only after I had left the van and was walking towards them that I realised there was a TV antenna on the house. This was a bit of a blow to my ego because it meant that the opposition had scored where I had failed. But that's the luck of the game and I was careful not raise the matter. So we yarned about the weather, its effect on the crops, and the season generally, in the usual way, until the woman said, "would you mind having a look at our TV set. We got it from your opposition but it's driving me up the wall. It has a terrible piecing whistle". Her husband's response was imme- SUPER SPECIAL LUMEN PC MIGHT-25 UPS: The affordable standby powersupply. • Designed specifically to back-up computer systems • Protection against mains brownout and blackout • 250 VA, 240V 50Hz output. • Fully self-contained, automatic operation • Inbuilt mains filtering and o/load protection • Typically 6 minutes backup diate and somewhat spirited. "Ya got whistles on the brain, woman. There's nothing wrong with it". By mutual consent, we ignored him and the lady ushered me inside. She switched on the TV set and we waited for it to warm up. I had a good idea of what to expect but I was a little worried that it might be too subtle for me to be sure about it, although my ears were better tuned to 15,625kHz in those days. But I needn't have worried; the thing was screaming its head off, as bad a case as I had heard. In the circumstances, I had no hesitation in advising the lady that she should insist that the trouble be fixed - or the set replaced if necessary. But no way should she tolerate it. And I gave her some background and a few pointers to let the salesman know she knew what she was talking about. So she thanked me, made me a "cuppa" and I took my leave. It would be wrong to say I didn't think anything more about it, because I was a bit miffed with myself for not doing a better sales job. How to blow a sale It therefore came as complete sur- ANTRIM TOROIDAL TRANSFORMERS THIS MONTH ON.LY: $399.00 FAXGUARO Surges and spikes, induced by lightning or power line faults can destroy your fax or computer. 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BOX 1174 GOSFORD STH NSW 2250 * All products are fully guaranteed • Authorised agent for Critec Aust. • Full range of surge arresting equipment for any application 56 SIUCO N CIIII' • Mail and phone orders welcome • We accept BankCard and VisaCard * I SY A to 62SY A :1vail:1ble ex-stock * I SY A to 2K YA :1v:1 il:1ble to order * Largest ex-stock source of toroids in Au stralia * Competitive pricing available for OEM s and resellers HARBUCH ELECTRONICS PTY LTD 90 George St. HORNSBY NSW 2077 Phone (02)476-5854 Fax (02)476-3231 TETIA TV TIP Hitachi CEP288, CEP289 (PAL3A chassis) Symptom: Reduced height, about 25mm of black at top & bottom of screen. No colour. The picture can recover to normal after 10 minutes but the fault does not appear to be heat sensitive. Cure: C753 (1 00µF/25V electro) open circuit. This capacitor is the input to the filter on the 20V rail and its loss causes the rail voltage to drop, in this case to 14V. The rail shows, no unusual ripple; just a lower than normal voltage. TETIA TV Tip is· supplied by the Tasmanian branch of the Electronic Technicians' Institute ofAustralia. Contact Jim Lawler, 16 Adina St, Geilston Bay, 7015. prise when, a couple of weeks later, the lady phoned and asked me to bring out a TV set for demonstration. Naturally, I had a set loaded and was on my way in nothing flat, but I was very curious as to what had happened. It was only after the set had been installed and running - without any whistles - that I learned the full story. What I hadn't known before was that the opposition's set was only on demonstration; no sale had been made. And, acting on my advice, the lady had made it plain that she wanted the trouble fixed. And that was where the salesman blew it. Whether he couldn't hear the whistle or could hear it but didn't know what to do about it, I don'.'t know. But he insisted, apparently quite curtly, that, "there's nothin' wrong with it". To which the lady replied that, if that was his attitude, he had better take the set away. And here he blew it again. He could still have salvaged the situation by offering another set. But no; he had apparently shifted into "high dudgeon" mode, loaded the set into his van, and gone on his way. Of course, his loss was my gain. The lady and her husband were both delighted with my set and, after a couple days' demonstration, the sale was concluded. So I scored a lot of goodwill for both myself and the firm, plus a very welcome commission. And now, in lighter vein, here's another off-beat story from my southern colleague, J.L., of Tasmania. Why do all the funny stories seem to come from down there? Is it because ... ? Anyway, here's how he tells it. TV TEST EQUIPMENT TO EARN YOU A HIGHER RETURN (Australian Made) SHORTED TURNS TESTER Built-in Meter to check EHT transformers including split diode type, yokes and drive transformers. The reluctant golf buggy Well, now I reckon I've done just about everything in the electronics repair field. A customer came in a week or two back and pleaded with me to repair the "volume control" on his golf buggy. Now this chap is well educated and, over the years I've known him, he's never been known to say something he didn't mean. So I had to believe that he really did have a volume control on his golf buggy and, because it involved electronics, I would have to try to fix it for him. In greater detail, as he explained the set-up, he had a motorised golf buggy and the so-called volume control was actually a speed control. That afternoon, during practise for the next day's championship match, the buggy had dug its wheels in and refused to follow him any more. He fiddled with the control and the buggy made "trying-to-work" noises, but didn't move an inch. He had to drag it around the final holes, and he didn't feel inclined to drag it around 18 holes the next day. So could I please do something about it? He had dismantled the buggy and had brought with him only the handle and the control. He handed me a short length of square section metal tubing with a black cable running through it. On one end of the cable was a 6.5mm stereo phono socket; on the other end, a perfectly conventional 5kQ linear switch pot. It certainly looked as though it should be part of some kind of audio system, hence his description of it as a "volume" control. I used a multimeter to check the 5kQ pot section and it appeared to be OK. Nevertheless, I opened it and checked the condition of the track. It looked perfect so I simply wiped it gently with a soft cloth moistened with contact cleaner, then reassembled it. Unfortunately, the switch part of the device was tightly clamped together and I feared I might not be able $78.00 + $3.00 p&p DEGAUSSING WAND Strong magnetic field, larger than usual coil with multicore centre. 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Double insulated for your safety. $84.00 + $5.00 p&p TUNER REPAIRS from $17.00 exchange + p&p Cheque, Money Order, Bankcard or Mastercard -;r-.v. TUNERS) :-:•:•·•:-·-•,:-:-:-:-:-:-:,::::::::•·-· 216 Canterbury Road, Revesby, NSW, AUSTRALIA, 2212 (02) 774 1154 ~~ (02) 774 1154 -a- JUNE 1991 57 SERVICEMAN'S LOG - CTD to refit the cover if I took it to pieces. It was a 2-pole, single throw switch and one pole was wired to the cable. This pole turned out to be faulty, being open circuit most of the time and closing only briefly as the contacts moved from off to on, or vice versa. Fortunately, the other pole was in perfect condition so I merely changed the wiring over to these terminals. I checked the cable for continuity, and the stereo socket for clean and firm contacts. All were in order, so I waited for the customer to return with the buggy. This proved 'to be a fairly conventional type of 2-wheel trolley with straps to hold the golf bag and a single handle with which to guide it. On the axle, to one side, was a surprisingly small DC motor geared to the axle. And on the other side, a battery box about the size one might expect to see on a motor bike. All in all, a most effective way to transport a golf bag. The motor speed control was obviously electronic and was housed in a small box mounted on the motor. The skQ pot was no more than a regulator and on-off switch but, being mechanical, was subject to wear, and it was this that had let the customer down.I haven't heard how he went in the championship match but I'm sure that he had no trouble with his buggy. Just the same, I thought the idea of playing golf was to exercise. Buggy fever But that wasn 't the end of the story. Last week he was back again, not with 58 SILICON CHIP his own buggy, but that of a friend with whom he plays each week. This time he brought the entire outfit, which appeared to have suffered the same fault as his had done earlier. It was a different brand from his but used an identical arrangement of parts and controls. I first tested the switch, which was perfect, then the continuity of the cable down the handle to the stereo socket. This differed a little from his, in that the socket was only a 3.5mm type as opposed to 6.5mm. But there was no problem anywhere to be found. I moved my attention to the short lead attached to the motor control box and, at first, I couldn't see any problem here either. Then I noticed that the tip was missing from the 3.5mm stereo phono plug. I wasn't certain which part of the circuit was involved with the tip, but it was obvious that the system wouldn't work with it broken. So I fitted a new plug. Now, if you ever repair one of these things, don't ever reassemble it on the bench. I made the mistake of reconnecting the battery while the control was switched on and advanced to top speed. The buggy took off along the bench and leapt into space before I could get my brain into gear. Fortunately, its wheels are very resilient and it bounced once', then headed for the door. I caught it before it got clean away, but the experience has taught me to be more wary of golf buggies in the future. I mean, TV sets and video recorders don't take off on their own, do they? It could'a been worse Fair enough J.L., and I'll take good care if ever one of these monsters finds its way onto my bench. But I can't help speculating on the scene had you not caught it. Where would it have finished up? Tearing down the main street, scattering pedestrians and vehicles in all directions? Or perhaps you don't have a main street, and it would have gone bush and never been found. Anyway, thanks again J.L. SC Howl suppression for public address systems Acoustic feedback is a problem with sound reinforcement systems. At a particular sound level, enough of the signal will be coupled back to the microphone so that a positive feedback loop is set up. This experimental circuit reduces this problem by shifting the whole audio spectrum up by 10Hz. By DARREN YATES If you've ever been in a lecture theatre or even at a concert, then you've probably heard the loud squeal that can occur due to acoustic feedback. This effect limits the number of locations where you can place loudspeakers, as well as how loud you can drive them. Acoustic feedback occurs when the resonance of a room at a particular frequency induces a positive feedback between the microphone and loudspeaker. Since theory says we only need a gain of slightly more than unity to start and sustain oscillation, the inevitable effect is that the PA system turns into a high power oscillator at the particular frequency of resonance. 35 0 30 25 a, ~ 2ll --- - - ~ n I n(\ MEANJlESPONg_ How it works This circuit concept was originally a design idea published a few years ago in "Electronics & Wireless World". That circuit used a couple ofMC1495 analog multipliers. We recently decided to take another look at the concept and use some lower cost and more readily available devices such as the LM13600/LM13700. A simplified block diagram of the frequency shifter is shown in Fig.2 while the full circuit is shown in Fig.3. It consists of, firstly, an audio stage using IC1a and IC1b, which incorporates a passive quadrature filt er net- t--- r "' z 0 c.. ~ The common way used by PA operators to overcome this problem is to introduce a dip in gain at the frequency of resonance, using a parametric equaliser or a one-third octave equaliser. This lets the overall gain of the system be raised until acoustic feedback again becomes the limiting factor. In practice , several dips may have to be used to make the system work at a sufficiently high level. This article discusses a different technique. If we take the entire audio frequency spectrum and shift it up by about 10Hz, we change the frequency response relationship of the amplifier and the room so that what used to be a frequency of resonance now becomes a frequency of something like "anti-resonance". To make this a little clearer, the graph in Fig.1 shows a typical room response to a section of the lower audio spectrum. As you can see, some of the p eaks are well above the average room response. It is at these fre quencies that we're likely to get feedback. You'll also notice that every few Hz or so above each frequency of resonance there is one of anti -resonance; ie, a dip. The idea behind this circuit is to shift the frequency spectrum up so that the frequency which is accentuated by the room response is now reproduced as a frequency which corresponds to a dip in the response, or so the theory goes. The end result is that we can increase the gain further before instability occurs. / .-----ix 15 "' 10 \I V OUTPUT 500 AUDIO MIXER AUDIO STAGE 0 520 540 560 580 FREQUENCY= INPUT•+ 1OHz 600 FR EOUENCY (Hz) '-----.-tX Fig.1: this graph shows a typical room response for the lower part of the audio spectrum. Acoustic feedback problems occur at the peaks. XY/101-----' Fig.2: block diagram of the frequency shifter. It shifts the incoming frequency by lOHz. JUN E 1991 5! al Q ,--------------<l>------+12V CJ) 11 r n 0 z n ::r: "O .001 0.1 10k .001 VR3 50k - 12V 0.1 +12V ~ 0.1 202 560k 01 WI,, r270k .,. VR6 100k 270k 270k ~ .I -:120k 270k ... 011'. -1 2V - 12V 01! VR5 50k +12V D1 1N4002 OUT 12VAC PLUG -PACK ,I:- I r +12V 0.1 100 - D2 1N4002 .1 I --- o,Il OUT GNO I I I .... I +V - 12V Fig.3: ICla & IClb generate two quadrature signals which drive the X inputs of 4-quadrant multiplier stages IC2a & IC2b. The Y inputs are driven by a lOHz quadrature sinewave oscillator consisting of IClc & ICld & the outputs then mixed & fed to amplifier stage IC3. - 12V 0.47 OUTPUT V OUTPUT IC2a OUTPUT IC2b Fig.4: trimpots VR3 & VR5 should be adjusted to obtain amplitude modulated waveforms at pins 8 & 9 of IC2, as shown here. work. The two quadrature signals (ie, out of phase by 90 degrees) are then connected to the X inputs of two 4quadrant multipliers, IC2a and IC2b. A quadrature sinewav·e source of about 10Hz is produc ed by IClc and ICld , and is fed into the Y-inputs of the two multipliers (IC2a & IC2b). The outputs are then mixed together and amplified by IC3 , where the final output is then connected directly to the PA system. In more detail, the input signal is amplified by the non-inverting amplifier ICla and an inverted copy is produced by inverting buffer IClb. IC1 is an RC4136, chosen for its low noise and low cost. The passive wideband quadrature network is connected between the two outputs of ICla and IClb. This produces two copies of the input audio signal which are 90 degrees out of phase. IC2 is a dual transconductance amplifier package, the LM13600. Each amplifier is connected as a 4-quadrant analog multiplier. The outputs from the two passive networks are connected via 4. 7kQ resistors to the X 0 inputs , which in this case are the inverting pins of IC2a and IC2b . 10Hz oscillator ICl c and ICld form the 10Hz quadrature sinewave oscillator. Th e two 6.8V zener diodes provide amplitude regulation and the amplitude itself is governed by the 100kQ pot, VR4. The two quadrature sinewaves are taken from output pins 10 & 12 and are connected to the Y-inputs of the two multipliers via two 50kQ pots, VR3 and VR5. These are really the inputs to the amplifier bias network, which control the gain of the amplifier and make it act as a multiplier. The output of each amplifier section is then connected external ly to the internal buffers (from pin 5 to pin 7 and from pin 12 to pin 10 of IC2) to provide a low -impedance output. The signals from each of the multipliers are then AC-coup led and mixed together via 100kQ pot VR6. IC3 is a TL071 FET-input op amp connected up as 'a mixing amplifier with a gain of about four. The output signal at pin 6 is then connected straight to the input of the PA system. The power supply is ±12V DC and can be derived from a 12VAC plug pack using a 7812/7912 3-terminal regulator combination. Setting up The setting up procedure is as follows: (1) Adjust VR4 so that the amplitude of the sinewave outputs at pins 10 and 12 of IC1 is about 9 volts p-p (about 3 volts RMS). (2) Connect a lkHz sin ewave source to the input of ICla. Adjust VR1 and VR2 so that the respective outputs at pins 8 and 9 of IC2 are as symmetrical as possible about the centre-line. What you'll find is that these outputs will tend to skew either up or down initially' and as you rotate the pot, they will quickly come into line. (3) Adjust VR3 and VR5 so that you get an amplitude modulated waveform at the respective outputs . The signal envelopes you end up with should be similar to those in Fig.4. As you adjust VR3 and VR5, you should get a normal amplitude modulated waveform and as you turn the pot, the waveform should appear to fold on top of itself, to produce a "bow-tie" effect (as in Fig.4). If you have a CRO handy, connect one probe to the output at pin 8 ofIC2 and the other to pin 9. What you should see are two similar waveforms, except that where one waveform appears to be at a min imum , the other should be at its maximum amplitude as shown in Fig.4. Finally, adjust VR6 so that the output of IC3 has as little or no 10Hz modulation as possible. Because the outputs of the two multipliers have the 10Hz carrier suppressed, mixing the output should give a steady amplitude signal with its frequency equal to the input+ 10Hz; ie, 1010Hz. Note that wh il e this frequency shift concept do es work, in practice we found that it was critical to set up and produced frequency non-l ineari ties of its own. SC PHONE LINE AND MAINS FILTER/SURGE PROTECTOR Protection for •Answering machines •Cordless phones ,,Facsimiles · •Computers •Modems •Telex The Arista model CPEP-1 ensures that lightning, power surges and spikes do not reach your costly communication equipment as it constantly monitors the PHONE line and the MAINS power line. Simply connect to any existing power point, plug in your fax, phone, video, Hi Fi or any other 240 VAC operated equipment and a series of indicators shows the status of the mains power point while several MOV's and gas arrestors prevents access to damaging energy sources. 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N ITOR M OVER ARM \ \% ) \~ ) A-. l ROD'S I lI COM PUTER TIPS IBM ·, XT·, TYPE I ctly where you want ximiae desk apace! 1 lid steel structure I look. X11105.. ....... ... ... ........ $250 Power supply to suit (220W) x11102 .... ........... s225 I p range 3cm -7.Scm ad SO kg 84 KEY KEY BOARD x12020 .. .. .•........ .......•.... ••s109 Give your computer that professional I an 33cm (tilting +I· 15) I l ~ MINI TOWER CASE 10+ $9.95 $9.50 11.5 x30m $9.95 $9.50 C20094 Size: 210 x 25.4 x 50m t ~·1J C20096 $19.95 $17.95 Size: 210 x 25.4 x 100m C20098 $9.95 $9.50 Size: 216 x 25.4 x 30m C20100 $11.95 $11.50 Size : 216 x 24.4 x50m C20102 $9.95 $9.50 [ RIBBON~ PRINTER RIBBONS TO SUIT: t/·" ~- r-- ·• . . ► -Z • CPSO, sxeo. DPBO, BX100, BX100, MB1 DO, 1-9 10+ C22036 ......... $19.95 $17.95 • MXBO,FXBO, RXBO, FXBOO. MX70. MXBO, LXBOO. C22031 ... ......$16.95 $15 .25 • MX100. FX100, RX100. 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Head 80 80 80 80 80 80 180cps 180cps 180cps 264cps 264cps 150cps 180cps 180cps 180cps 213cpa 192cpa 51/4"DISKa TOP OF THE RANGE AT EXECUTIVE CASE For 386 & 486 systems Inc ludes power supply X11101 .... ... .......... ...... .... $320 CANON LASER CARTRIDGES Why waste your precious time r::=\,gfb & money trying to get a quality print out from a "recharged" cartriclge when you can buy a brand new Canon laser cartridge from Rod Irving for only $199.001 UV EPROM ERASER It will erase up to 9 x 24 pin devices in comp1ete safety, in about 40 minutes (less time for less chips) • Chip drawer has conductive foam pad • Mains powered • High UV Intensity at chip surtace ensures EPROMs are thoroughly erased EP CARTRIDGE FOR SIDE LOAD ING PRINTERS C211 07.... ...... ............... .......$199 EP-L CARTRIDGE FOR FR ONT LOADING PRINTERS c2,, o9 ........ ..................... ...s199 EP-S CARTRIDGE FOR TOP LOADING PRINTERS C211 08 .. ............. .....•.. .. ....... $199 Without timer X14950 .................... .$99 With built-in timer X14955 ........ .... ....... $169 $325 $499 $395 $995 $1195 $625 $795 $299 $695 $499 $799 ~::a: :r:o ·· · . · · /j!;il'.=;;=;;") · KEYBOARD Keyboard & mouse in one x, 2030.6 - /..$199.95 84.95 MINI VACUUM CLEANER C21087 .. ~ ...$14.95 DISK BOXES POWER SUPPLIES POWER SUPPLY FOR IBM •, PC/XT", & COMPATIBLES DC OUTPUT: +5113A -5 0.5A +12V /4.5 ·12 VO.SA X11096 ..... .... ..... ....... .......$109 200W SWITCH MODE POWER SUPPLY FOR IBM•. AT • & COMPATIBLES DC OUTPUT : +511 6A -510.5A +12Vl4.5 -12V I SA -1210.5A X11097 ... ...... ........ ... ... ..... $149 ~ .L • ~ 100 x 5 1/4" ECLIPSE C16042 ... ..... ..... ... ... .... .$11.95 40 x 3 1/2" ECLIPSE C16040 ....... ................. $8.99 120 x 3 1/2" LOCKABLE C16039 ... .... .. ............. ..$21 .95 100 x 5 1/4" LOCKABLE C16020 .. .. .. ................. ..$13.95 50 x 5 1/4" LOCKABLE C16025 .... ... ............. .....$11 .95 120 x 5 1/4" LOCKABLE C16028 .... ....... .............. $19.95 PRINTER SWITCHES RS232-2 WAY ..... ... .. .......... $39 RS232-4 WAY .... ..... ........•... $69 RS232-X OVER .. ... ........ ...... $69 RS232-2 WAY AUTO .... ....... . $69 CENTRONICS 2 WAY ......... .. $49 CENTRONICS X OVER ....... . $69 CENTRON!CS 2way auto ..... $79 CENTRONICS 4 WAY........... .. $69 Hii 'S'"'"' ENCLOSED PRINTER STAND cm•~···'"·" / •·~ · · LASER PRINTERS OL400 LASER PRINTER 4 PAGES / MIN 25 FONTS .......$1,895 OL800 LASER PRINTER 8 PAGES/ MIN 36 FONTS ...........$2,595 OL840 POSTCRIPT LASER PRINTER 8 PAGES/ MIN 35 FONTS ......... $4,495 o· QUICK MOUSE Microsoft Compatible °,al: · house & mouse KEYBOARD COVERS C21089 84 KEY..... ..... ..$4 .50 C21088 101 KEY... ......$5 .95 On a 5 1/4" disk you • have to cover up the notch as shown in the side of the disk with your protective device called a write -,,oi oct tab. They usually come in btack or silver. Transparent tabs should n ot be used becau se write protects work optically. Regards Rod irving. LOW BUDGET! ~ . , FREE MOUSE DRIVER & POP UP MENU SOFTWARF.I X19950 .......................... $49.95 FREE mouse 101 KEY TRACKBALL C21083 .. ~ RITRON EXECUTIIVE CASE X11089 ...... ..... ... ............ $119 P.S to suit X11089 ...... .$149 I 3 3 3 3 6 3 4 3 3 5 colour 6 colour ,. ; ~ 31 /2" On a 3DISK. 1/2" disk you have to ~ slide open the plastic • tab to reveal the write protect hole. No.of col. Draft Speed NoJ Fon la Price ~ IBM COMPATIBLE EXTENDED KEYBOARD (101 KEYS) x12022 ....... .. ............•. ..... s109 KEYBOARD STORAGE DRAWER • 10 metres P19034 ...............................$39.95 9 pin 24 pin 9 pin 24 pin 24 pin 24 pin 24 pin 9 pin 24 pin 200-GX" 9 pin GSX 140" 24 pin I EVER POPULAR, I onltorl o -- GREAT PRICE!*** I 1 .... "\.~' ) ""~? ";:1_ r':'-.." ., \e,~:.,/ -') DELUX PR INTER STAND C21058 .. ..... .. ........... ....$89.00 ~ WIRE PR INTER STAND C21054 •... 80 colurM ........... $24.95 C21056 ... .132 ColurM ........$34.95 mat Plus FREE . pop up menu software X19955 ....... ... ........... . $69 .95 SUPER BUS MOUSE 2 DESIGNED TO AT THE PALM ·,, / ·; OF YO UR HANOI / GREAT FOR SAVING A SERIAL PORT! 2 FREE TELEPAINT DISKS! X19951 .... ....... .. ... .. .........$119 TOUCH MOUSE "A Stationary Breakthrough" Use your finger instaed of your mouse . Great I saving space. Ideal for laptops V x19; :~ ~~ : ; ~: :;i~i ;9 I ( Supports hunderda of I :~~~•Ilona ~ r -./"'.. I . ~ ~/,:>~, M1CFTWROSAORFTE ,{ ~ • PAINTBRUSH C.,~ _/ S0 BRINGS YOUR COMPUTER TO LIFE. ' _j "1 - "" ~ XT HO CONTROLLER .... $129 AT HO CONTROLLER .... $199 RS2321SERIAL CLOCK. ............................ $49 MONO COLOUR CARD .. $76 MULTI OL ...................... $99 VOICE MAIL.. .................. $199 PRINTER CARD .. ........... $29 EGA CARD ........ .......... .... $149 DIAGNOSTIC ................... $795 TTUPRINTER. .......... :...... $89 RAM 2!,I AT EXT/EXP. ..... $225 SM AT EXTIEXP............... $325 FAX CARD ....................... $595 4 PORT SERIAL. ............. $129 2 WAY FOO CONT (360K). $39 RS232/SERIAL CARD ..... $39 GAMES CARD ................. $29 AT SIPIG 1 S/PIG............. $43 AT SIP/G 2 S/PIG............. $49 . 4 WAY FOO CONT. (360-1.44M)...................... $129 2 WAY FOO CONT. (360-1.44M) ..... ................. $80 CLOCK CARO ................ . $39 SMART DRIVE ADAPTER iOE!FDC ....... $49 SMART DRIVE ADAPTER IDE 1:0 FOC ... $89 VGA CARD 16 BIT NO RAM ..................:$199 VGA CARO 16 BIT 250K ................ $229 VGA CARD 16 BIT S12K .................. $269 VGA CARD 16 BIT (1 MEG) .......................... $299 VGA CARD 8 BIT 256K .•••. $189 .• r ./if QuickS ot Joysticks HAVE THE CUTEST MOUSE INTHE HOUSE WITH THESE GREAT NF.W Quick Snot offers the moat complete aelectlon of video game controllers CPF CONTINUOUS POWER FILTER SPIKE ARRESTOR The Fortran CPF Filtered Electronic $pike Protector provides a protective eleClrOl"IIC barrier !Or microcomputers. printers, telephone systems and modems electronic typewnters. audio and stereo systems and other sensitive electronic equipment The CPF provides protectJOn from dangerous electrical spikes thal can cause anything lrom obvious damage (like immediate equipment failure) to less obvlOUS harm that can drastically shon en a sys tem 's life CPF's superior c1rcui1ry design and semi conductor technology responds 1nstan1 1y to any potentially d amaging over-voltage, ensuring safe trouble A simple way ol moniloring AS232 interface lead activity. Interf ace powered. pocket size lor circuit AC. OTA. (EJTC X15700 . .. . . $99.95 helps ellminate troublesome and ~~e~~~~n;~rr~~~~;i.1~~r~:c :i 85 Cat. XlOOBB $69.95 SOFTWARE ! PC PAINT BRUSH & IMAGE TOO L • Wide 4.13" (1 05mm) Scan width SPECIFICATIONS: Connectors: 0825 plug on 80mm ribbon cable and 0 B25 socket Indicators : Tricolour LED's !or TD. RD. RTS, CTS, CSR. CD. TC. Jumper Wires: 20 11nned end pieces Power : Interf ace power. Enclosure : Black . high Impac1 plashc. Dimensions : 85 K 95 K 30mm OS-123 WARRIOR 5 IBM COMPATIBLE (15 PIN C14208 .......... $59.95 APPLE& IBM COMPATIBLE (9 & 15 PIN CONNECTORS) DISK ~OTCHER Co n ve rt s S 1/4 " singl e ~i d cd flopp y d is ks to d ouble si ded , b y placing an a pp r opri at e n o tch in t h e fl o ppy d is k jacket. C12614 ... ...... ... .. $59.00 JOYSTICK FOR IBM ,,,,,- Features selectable "spring centring" or "free floating ". Electrical trim adjustments on both axle. 360 degree cursor control · C21070 ........... ...... . $7.95 Ideal for games or word processing. fits most 6502 "compatible" computers. C14200 .... ..... ..... $29.95 • Thrity-two shades of grey. • Built in scanner view window for accurate scanner placement. X19945 ...................$295 OS·123 PC IBM PACK INCLUDING JOYSTICK ADAPTOR CARD (15 PIN) C14217..........$74.95 Be the first in your office to ha ve a mouse that every one will want use. This cute little mouse cover puts a bit of fun and colour onto your desk whil e keeping your mouse free of dust! C21069. w... .. "• :.. L.F . ... $7.95 · !//) MOUSE CLEANING KIT \ '~ ~ \ THE BUTTON SPIKE PROTECTOR Surges and spikes are caused not only by hghtrnng strik es and toad sw1tch1ng but also by other equipment bemg switched on and ott. such as lluorescen! lights . electric motors. fridge freezer s. air cond11toners. etc For eHect1ve protec1,on such spikes must be s10pped belore they reach your equipment s ,mply plug The Bun6n into an out1el and 11 will protect all equ,pmenl plugged In10 ad1acen: oullels on !he same br anch cIrcuIt The Bunon employs umque me!al OK1de varisler technology and w,11 dIss1pa!e 150 1oules ol eleclncal energy (nearl y twice that ol comparable s~rge arresters I SPECIFICATIONS : Voltage 240V Nominal . GENI SCAN COLOUR SCANNER The GS-C1 05 Colour scanner scans any colour or black & white image into your IBM PC AT, PS-2 or compatible system without loaa of hue . FREE SOFTWARE! Draw shapes, modify oblee1s alter colours & edit a palette of 256 colours using the commands on your pop-up menus. You can even design your own font type size. • 105mm scan width , multi scan up to 300mm • 64 shade levels X19930 .. ......... .. ...... $795 Keep dust and dirt from damaging your mouse with this handy mouse cleaning kit. This special rounded tool will find its way into all the hard to get at places. The kit also comes with clea nin g fluid and 5 soft cloths to keep your mouse spotl ess I C21071 ...... ..... ... ... $9.95 El MOUSE KIT Everything yo u need to keep your mouse happyl You get a mouse pad, a mouse holder, a cleaning kit (previously described) and a cute little mouse cover. C21072 ... ................ $16.95 C14214 .......... $39.95 A working bench for your Mouse. •High qu!l,lity ABS plastic and anti-static rubberi sed lop DUST COVER Keep your compu ter and accessories free of dust and grime while not in u se XT• Cover Set C21066 .... ....... ....... $14.95 AT• Cover Set C21068 .... ... .... ....... $16.95 •Stationary holder •Includes pull-out shelf for Mouse •Dimensions : 280 x 260 x 25mm MOUSE GIFT SET Here it is! The ultimate mouse kit. You get all of the abo ve products, the cute little mouse cover, the mouse cleaning kit, the m ouse house and mouse pad all in a handy black case. C21074 .. ..... ... ...... .. $19.95 • Fits o ver keyboa rd OS·130N/F DELUX DIGITAL NINTENDO& MULTISYSTEM COMPATIBLE (7 &9 PIN) C14209 .......... $39.95 POCKET AUTO AB SWITCHES • Pockel size, auto-sca nning • Allows 2 PCs to share one Printer Ll I .. Serial model : 1\15-201 - Host-powered X19150 ... ............... $79.95 Parallel model : MP-201 Protocol transparent X19155 .. ..... ....... ....$89.95 ~-t:**** C21006 .. .........$9.95 279mm x 241 mm 500 sheets C21007......... $16.95 True A4 296mm x 210mm 250 sheets C21008 ......... $14.95 True A4 296mm x 210mm 500 sheets C21009 ......... $19.95 ~ ' P19038 ..... ........ ....... $9.95 OS·129N/F SPACEAGE CONTROL NINTENDO & MULTISYSTEM COMPATIBLE (7 OR 9 PIN) C21080 On special was $24.95 Now....... $1 4.95 High quality 70 gsm, convienienty packed continuous fan- fold c o mputer paper. Comes i n packs of 250 or 500 sheets In two sizes. 279mm x 241mm and true A4. Very usefu l for photocopying computer print-outs w ithout having white space on the top or bottom of the page. 279mm x 241mm 250 sheets EXTENSION LEAD $42.95 MAGIC STAGE Introducing ComPstat! 5 Pin Din plu g and socket ~~~~!~se:o/i: ;ir1~n~ 50 1ou1es Prolec11on Level 350V peak C14205 ............ $49.95 APPLE* COMPATIBLE JOYSTICK patterns. ,_"_ C14216 ..........$59.95 tores up to 120 M/Byte • 100/200/300/400 awttchable DPI resoluti on • Four ericoded modes: B/W and three half tone C14211 ..........$62.95 OS113PC IBM PACK INCLUDING JOYSTICK ADAPTOR CARD (15 PIN) DAT ALIFE DL-600 DATA CARTRIDGE HS-3000 HANDY SCANNER INCLUDES FREE ~~~~ia':1~ ! ~~iJ ( ~ ~a~~~ing. 2 spares. 24 switches enables you to break out circuit s or reconr~ ure and patch any or all the 24 active positions. free operation Addition~lly. CPF's liltenng capabd11Y e lamps, and the like thal threaten the . per1ormance and shorten equipment tile of unprotected electronrc components SPECIFICATIONS : Electrical rating : 220·260 volts (AC) 50Hz 10 Am p Spike/AFI Proteclion : 4.500 amps for 20m/second pulses Maximum clamplng voltage: 275V differential mode. In the markel Models •r~ available to suit all the moat popular video game machines and just about any playing style. WE HAVE ENLARGED OUR RANGE OF COMPUTER PAPER! SURGE BUSTER cau se problem s: er r o r s, d own t i m e o r an ex pensi ve se r v ice <:al l. Regu lar u se o f a h ead clea n er will keep you r dri ve free o f troubl e cau sing di rt and h elp keep yo ur system up an d running . These di sk cl eaners arc simpl e to u se, and includ<' cl eaning solut i on and instru t ti on i . COMPUTER CLEAN ING KIT SPECIFICATIONS: • Electrical rating : 240V AC. 50Hl, 10A • 3 x Metal Oxide Varislors (MOY) • Maximum clamping Voltage : each MOY: 710 volts at 50 amps • Response time: Less than 25 Nanoseconds. QS.131 NEW BASIC ATARI / COMMODORE .g PIN C ! 2560 ....... ...... .. .. $6.95 ·ro gain optimum performance and pre vent damage to valuable d isks, this cleaning kit has all you need to keep your computer in top notch performance. Anti-static cleanin g pads, cleaning swabs, cleaning solution, 5 1/4.. & 3 1/2.. cleaning diske ttes. • S 1/ 4" C210'tl .. ..... ....... ..... $19.95 X10086 .....................$69.95 C14218 ..... .....$1 9.95 C ! 2555 ... .... ..... ..... $6.95 6 PROTECTED POWER OUTLETS kJeat for protecting personal compu ters. video equipment, colour TVs, amprtllers, tuners, graphk: equalisers, CO players etc • j 1/ 2" ELECTRONICS SYDNEY : 74 Parr amana Ad Stanmore 2048. Phone 102) 519 3134 Fax (02) 519 3868 MELBOURNE: 48 A'Becken S1 Phone (031663 615 1 NORTHCOTE : 425 High S1 Phone (031 4898866 CLAYTON: 56 Renver Rd Phone (03) 543 7877 MAIL ORDER & CORRESPONDENCE: P 0. Box 620. CLAYTON 3168 Order Hothne 008 33 5757 (Toll free . stnctly orders only) lriqumes . (03J 543 7877 Telex AA 151 938 HEAD C I. EA1'F.R DISKS It on l )' t ak es a m inut e amount o f dust , di rt o r magneti<: o xidl' pa rticl e s o n y our drive h ead .\ tu ***** RODIRVING Fax· (03) 543 2648 All sales tax exempt orders and wholesale inquiries to : RITAONICS WHOLESALE. 56 Ren ver Road. Clayton Phone (031543 21 66(3 lines) Fax (03) 543 2648 For postage r1te1 re fer to other R.1.E. advertisement Errors and omIss1ons excepted Prices and speohca11ons subject 10 change. :=.:IQ~T~~!.;.:is•~.: ::I•=•"::~ ,eg,s1ereo r,aoem,,.., ·0eno1n r~ s•erto 11-aru o, , - ,- ,,..e ow,,.,s JllffiZ \I 13.5V 25A power supply for transceivers, Pt.2 In this second article on our 13.5V 25A power supply we give the construction details and the setting up procedure. Most of the work involves assembling the PC boards and mounting the hardware in the chassis, there being relatively little wiring required. By JOHN CLARKE & LEO SIMPSON Because this power supply uses Triac control for regulation, it is quite efficient and therefore dissipates a relatively small amount of power in the chassis. This means that big heatsinks and fans are not necessary and as a result, the overall construction is quite simple. It uses a conventional 3-unit high rack-mounting case with two PC boards mounted on the base panel. There are two transformers, one a large 625VA toroidal type and the other a miniature conventional type. There are also the two iron-cored 64 SILICON CHIP chokes and the four stud type rectifiers which mount on heatsinks on the rear panel. Although two PC boards have been designed for this project, you may end up using only the control board, depending on your constructional approach. The control board is coded SC14105911 and measures 165 x 125mm. As its name suggests, it carries all the control circuitry. The second PC board is coded SC14105912 and measures 180 x 176mm. We used it to mount the two 80,000µF banks of capacitors which were all PC-mounting types. However, if you purchase chassis mounting filter capacitors, this board would not be necessary and the capacitors could all be har:d-wired. We'll talk more on this aspect later but from here on, we'll assume that both boards are to be used. PC board assembly You can begin construction by assembling the control board. First of all, inspect it carefully for any defects such as breaks in the tracks or shorts between adjacent tracks, undrilled component holes and so on. Correct any of these before you install any components. Follow Fig.4 carefully when assembling the control board. You should check your work against this diagram and the circuit diagram (Fig.2) published last month. If you look at the PC board depicted in Fig.4, you will notice that the components in one corner are rather sparsely laid out; ie, they seem to occupy more than their fair share of 12.6V _....... D5 fl 06 ---t:a---- 7805 7905 •G• I 0 • I• 10uF 10uF • Fig.4: here's how to install the parts on the control PC board. Note that the Triac is installed from the copper side of the board (see text) and that IC3 faces in the opposite direction to the other ICs. The SCR is initially left off the PC board & is installed only after the crowbar circuit has been adjusted for correct operation. • G 0 ·O ·O LJ MOC30218 1 space. There is a good reason for this because these components (ie , the MOC3021 optocoupler, the Triac , toroidal inductor L3 and the associated resistors) all operate at mains potential (240VAC). Begin the board assembly by installing the 12 PC stakes. These are for the external wire connections and for the indicator LEDs. Next, install the low profile components such as the ICs, resistors, diodes and links. Be sure to orient the ICs correctly (note: IC3 is oriented differently to the other four ICs). Take care also with the diode orientation and be sure to use the correct diode type at each location. Diodes D5 , D6 and D14 are 1N4002s, while the remaining diodes are all 1N4148s. When installing the three 1W resistors in the mains section of the PC board , push some clear insulating sleeving over the each resistor body and its wire leads. This will prevent accidental contact and the possibility of electric shock. Now you can install the capacitors. All the electrolytics, except for th e 2.2µF bipolar type , must be oriented correctly as shown on the overlay diagram. This done, install the regula- 1 .~ t ... i 9iii¥t:. J·'~ .) 1t t lT '_ ' ----...... "i--.--- --··~-~· --- - 'Ii.ii-·- ~~ -.- ' rfi ._.__-._._-J 1a r~ IIII I ;ij. The parts at the top lefthand corner of the control board all operate at mains potential so be wary of this part of the circuit. Note that plastic sleeving has been fitted to the three 1 W resistors to reduce the possibility of electric shock. tors and transistors , making sure that you install the correct transistor type at each position. Do not install the MCR69-2 SCR at this stage. This will be don e after the crowbar circuit has been adjusted for correct operat ion. Also, the two LEDs should be left off until the PC board is JUN E 1991 65 0 TOL2 ... ◄ ~ TO ANO OES,OF 03 , 04 ~ - \ TO NEGATIVE OUTPUT TERMINAL VIA CURRENT SENSE TO GNO OF CONTROLLER BOARD TO FEEDBACK INPUT OF CONTROLLER BOARD Fig.5: the capacitor bank board carries the 16 10,000µF capacitors plus the four 560 5W resistors. Mount these four resistors slightly proud of the PC board to allow the air to circulate under them for cooling. The current sense resistor consists of a 150mm length of 1.25mm enamelled copper wire (see Fig.6). which is so ldered to two points on the board. Installing the Triac to be final ly install ed into th e case. Trim pots VR1, VR2 and VR3 plu s th e va ri stor can now be so ld ered into pl ace. Winding the toroid Inductor L3 is wound with 45 turn s of 0.63mm ename ll ed co pper wire on a Neosicl 17/.742 / 22 toroid al former. Cut a 2- met re length of th e wire an d s trai ghten it by anc horing one end in a vycc and pu lli ng th e oth er end with pliers. Pul l th e wire just enough so that it gives a littl e and bec omes d ea d s trai ght. Thi s removes a ll th e littl e kinks and hends an d gives yo u a ni ce strai ght length of wire to work with. The toroid is th en wound in two stages. working from th e cen tre of th e wire, as it wore. Fend one metre of wirr! through tlw cent re of th e toroid and w ind (or thread throu gh) about 66 SII.IC:() ,\ ' Cl/11' 22 turns, as even ly spaced as possible. Thi s d one, w in d the other en d of the wire onto the toroid to make up the full 45 turns . Cut th e ends of the winding to a reasonable length, remove the enamel in su lation by scrap ing it down to bare copper w ith a utility knife, and then sol der the inductor to the PC board. The inductor is th en furth er secured using a tinn ed copper w ire strap The Triac is mounted on the u nderside of the PC board w ith its leads bent upwards into the mounting h oles . Bend the leads at right angles so that the lower face of the Triac body is 6mm below the bottom of the board. This w ill all ow it to be bolted directly to the base of the chassis when the board is mounted on 6mm spacers. That completes the control PC board assembly for the moment. You can now start work on the capacitor board. Capacitor board CAPACITOR CODES 0 0 u ;_j [.J Value IEC Code EIA Code 0.1µF .027µF .022µF .01µF 100n 27n 22n 10n 104 273 223 103 This PC board accommodates the 16 10,000µF capacitors plus four 5W resistors. Begin construction by checking the hole sizes for th e five heavy cables. Th ey should all be drilled to 3mm - see Fig.5 . The assembly of th is PC board is straightforward, since the capacitors can only be installed one way due to the fact that each can has three leads. The third short lead is actually a support lead and is not electrically connected to the capacitor. It must be soldered to the PC board though, to properly anchor the capacitor in place. Due to the large copper area of this PC board , you may have problems soldering with a normal low power (30W) soldering iron. If this is the case, try to obtain a 60W heavy duty iron for the job. Be careful not to overheat the capacitors when using this iron, though. The four 56Q 5W resistors should be installed so that each resistor body sits about 1mm above the board surface. This will allow better ventilation for the .r esistor and avoid any tendency to char the board - these resistors do get very hot. Finally, install three PC stakes to terminate the external connections . This close-up view shows how the wiring to the binding post terminals is run using heavy-duty cables and connectors. Note also the enamelled copper wire loop that forms the current sense resistor. It runs between the capacitor PC board and the negative output terminal (right). Chassis preparation Fig.6 shows where the various components are mounted in the case. Start by temporarily placing all the heavy hardware items in position on the base plate. These include the two transformers, the two iron cored chokes and the two PC boards. Once everything is in position, mark out the various mounting holes, then remove the parts from the chassis. The holes can then be drilled and deburred . Make sure that the mounting area for the Triac is clean and abso lutely free of metal swarf and paint. The paint can be cleaned away using fine grade emery paper. Because the Triac normally only becomes slightly warm during operation, you might think that heatsinking it to the chassis is not really necessary. However, if it is subjected to a quick series of power up/down cycles or if a fault condition occurs, the Triac may become hot and this is when the heatsinking is required. After you have cleaned the paint away-from the Triac mounting area, do the same for the chassis area around the main earth lug (near the mains cord entry point). This must be done to ensure a good earth connection to the chassis. The rack case specified is supplied unassembled. This means that you can mount all the base panel hard- RESISTOR COLOUR CODES D D D D D D D D D D D D D D D D D No. 9 1 2 3 9 2 1 5 5 3 4 Value 470kQ 150kQ 100kQ 47kQ 10kQ 4.7kQ 3.3kQ 2.2kQ 1kQ 680Q 560Q 390Q 330Q 100Q 56Q 47Q 4-Band Code (5%) 5-Band Code (1%) yellow violet yellow gold brown green yellow gold brown black yellow gold yellow violet orange gold brown black orange gold yellow violet red gold orange orange red gold red red red gold brown black red gold blue grey brown gold green blue brown gold orange white brown gold orange orange brown gold brown black brown gold green blue black gold yellow violet black gold yellow violet black orange brown brown green black orange brown brown black black orange brown yellow violet black red brown brown black black red brown yellow violet black brown brown orange orange black brown brown red red black brown brown brown black black brown brown blue grey black black brown green blue black black brown orange white black black brown orange orange black black brown brown black black black brown green blue black gold brown yellow violet black gold brown JUNE 1991 67 <at> \ _ BxHEATSINK SEQIB!!fG / SCREWSAll!)_<at>.!§_ <at> L2 BROWN MAINS ERMINAL BLOCK CONTROLLER PCB LE01 <at> LE02 •K •A •A •K - - - - 7.SA MAINS RATED WIRE === 3.2mm2 INSULATED COPPER WIRE FRONT PANEL + Fig.6: here's how everything fits together inside the rack-mounting case. This circuit carries quite high currents, so be sure to use the correct gauge of wire where this is indicated. Sleeve all mains connections with heatshrink tubing to avoid the possibility of electric shock. ware before the side panels are fitted. The front panel can be now be drilled to accept the power switch , the two LEDs, the binding post terminals and the fuse holder. You can use th e front panel artworks to guide you when marking the positions of thes e components. Note that th e holes for 68 S1uccm C111P the LEDs must be drilled so that they line up with their mounting positions on the control PC board. Make these holes big enough to accept the clip-in bezels. To make the rectangular cutout for the power switch, drill one large hole in the centre and a series of closely spaced smaller holes around the inside perimeter. You can then file out the hole so that the switch fits neatly in position, with the plastic side lugs holding it securely. Once all the holes have been drilled and deburred, the self-adhesive Dynamark labels can be attached to the front panel. Check that they are correctly aligned with the holes and that they are square with the panel before sticking them down (once the e (l) e~SECURING SCREWS TO REAR PANEL HEATSINK - INSIDE CASE Fig.7: the four studmounting diodes must be isolated from the heatsinks using mica washers & insulating bushes as shown here. Smear both sides of the mica insulating washers with heatsink compound before bolting the diodes in position, then use your multimeter to check that the diodes are correctly isolated from the heatsink. Be sure to use the correct diode type at each location. GROMMETS FOR LEADS THROUGH REAR PANEL adhesive grabs, that's it). The holes in the two panels can then be cut out with a sharp utility knife. You can now install the front panel components and attach the front panel to the case. Rear panel The rear panel must be drilled to accommodate the fuse holder, the mains cordgrip grommet and four 6mm ID rubber grommets. In addition, you have to drill eight mounting holes for the heatsinks plus clearance holes for the four stud-mounting diodes (D1-D4). The first step is to drill the heatsinks - see Fig. 7. There are four mounting holes on the outermost fins plus two diode mounting holes for each heatsink as shown. Make the diode mounting holes large enough to accept the insulating bushes and carefully deburr the holes to avoid puncturing the mica insulating washers. Once the heatsinks have been drilled, you can use them to mark out the rear panel mounting holes and diode clearance holes. Use a small pilot drill to drill the diode clearance holes to begin with, then carefully ream them out to 25mm using a tapered reamer. heatsink carries two 70HFRZ0 (reverse polarity) diodes. If you mix them up, you will blow fuses and maybe even blow the diodes. Note that stud diodes D1 and DZ on the main wiring diagram (Fig.6) are "R" types (reverse polarity}, while D3 and D4 are normal polarity types. Normal polarity stud diodes have the cathode (K) connected to the threaded stud and the anode to the centre lug. Reverse polarity stud diodes have the anode connected to the stud and the cathode to the centre lug (see Fig.7). The diodes specified (ie, 70HFZ0) are rated at 70 amps and have a Z0V inverse rating. However, you can also use higher inverse voltage versions such as the 70HF40 (40V) or 70HF60 (60V). To wire the diodes, you will need the diode mounting hardware, four Utilux lugs and heavy duty cable. The cable we used is actually figure -8 speaker cable w ith a conductor cross section of the 3.2 square millimetres (DSE Cat W-2015 or Jaycar Cat WB1732). You will need one metre of this figure-8 cable which can then be split into two lengths. Mounting the stud diodes Once all the drilling has been completed, the four stud diodes can be mounted on the heatsinks. There is a trap here for young players, so pay attention . One h eatsink has two 70HFZ0 diodes on it while the other The four stud-mounting diodes pass through 25mm-diameter clearance holes drilled in the rear panel. The connections to these diodes are run using heavy duty (3.2mm 2 ) cable and are made using a heavy duty iron before the diodes are attached to the heatsinks. JUNE 1991 69 Smear heatsink compound on the back surfaces of the heatsinks before bolting them to the case. The heatsink on the left carries the 70HFR20 diodes while the one on the right carries the 70HF20s (make sure that you don't get them transposed). Tighten the diode nuts firmly to hold them in position. The Triac is installed from the copper side of the control board & bolted directly to the chassis. No mica insulating washer is necessary here since the Triac specified is an isolated tab type. 70 SIUCON CH71' It is necessary to solder the leads to the diode lugs before mounting them on the heatsinks. If you don't, the heatsinks will draw too much heat away from your so ldering iron for reliable soldering. Note that the bared ends of wire should have their plastic tracer inserts cut before the wire is twisted and inserted into the lugs. To make for a professional job, we used heatshrink tubing over each lug. The diodes can now be mounted on the h eats inks as shown in Fig. 7. Before bolting each diode down , smear both sides of the mica insulating washers with heatsink compound to improve heat transfer. Each diode is supplied with a star washer but this should be discarded since it does not allow enough thread length for the diode stud. Do not overtighten the nuts. Once the diodes are mounted, use your multimeter to check that the diode bodies are indeed correctly isolated from the heatsink. Note that the heatsink is anodised and that this provides some degree of insulation. For a good multimeter probe contact, use the exposed aluminium in the mounting holes. If everything checks out OK , the heatsinks can be bolted to the rear panel. Once again, it's a good idea to use heatsink compound on all mating surfaces to improve thermal transfer. Feed the diode leads through the grommets in the rear panel, then screw the rear panel to the case. Wiring All that remains now is the chassis wiring. Strip back the insulation on the mains cord so that the Active (brown) and Neutral (blue) wires are about 35cm long, to reach the power switch with slack to spare. The Earth (green/yellow) lead is cut back to about 10cm and soldered to the earth lug near the cord entry point. Secure the earth solder lug to the chassis with a machine screw and nut plus a star washer. The brown Active lead connects directly to the fus eholder on the rear panel. Pass this lead through some heatshrink tubing before soldering the wire to the fuse holder. This done, solder the remainder of the Active Below: all the major hardware items are easily accommodated inside the rack-mounting case. Use cable ties where necessary to keep the wiring tidy & be sure to install the mains wiring in a professional manner. 13.SV 25A POWER SUPPLY POWER OUTPUT REGULATED CROWBAR + '----13.SV _ ___.I 30A FUSE Fig.8: these artworks can be used as guides when drilling the front panel. JUNE 1991 71 .I a Fig.9: check your control board against this full-size pattern & repair any defects before mounting the components. wire to the second terminal of th e fus e holder and pass it through the tubing. Now the tubing can be pushed onto th e fuseholder to cover th e terminals and shrunk down using a hot air gun. Before soldering th e leads to th e pow er switch (S1), slide some large diameter insulating tubing over the wires so that it can be shrunk right ov er the switch body (see photo). Th e transformer secondary wires are terminated in Clipsal 563k16 connectors. As suppli ed, these connectors have a blind end on the plastic insulation and this will have to be cut off to allow wire entry from both ends. Strip the enamel away from the transform er secondary wire ends before securing them in th e connectors. Th e wires from th e cathodes of diod es 03 and 04 and the anodes of diodes 01 and 02 al so terminate in the: C:lipsal connectors. As noted previousl y, be very careful to ensure that this wiring is correct. The 2111£2 current sensr: rnsistor from 72 SIUCO N C/111' the capacitor PC board to the negative output terminal consists of a 150mmlength of 1.25mm enamelled copper wire. This wire is simply formed into a single large loop and soldered to the PC board and to the output terminal lug. Note that the eyelet lugs supplied as part of the binding post terminals are inadequate for the current rating of the power supply. Use heavy duty eyelet lugs for all connections to these terminals. Transformer T2 (2851) has a centretapped secondary, although the centre tap (blue) is not used. The two yellow wires from the transformer connect to the controller PC board. Cut back the ce ntre tap lead so that it cannot accid entally contact any part of the chassis or PC board. The remaining wiring can now be completed as shown in Fig.6. Use cable ties and clips where necessary to keep the wiring neat and tidy. Testing Now that th e wiring is complete, the power supply is ready for testing. Do not apply power yet! First, rotate trim pots VR1 and VR3 fully anticlockwise and set VR2 almost fully clockwise. Before switching on th e supply, we recommend that you secure the lid to the cas e. This will protect you against any catastrophic fault which may cause molten material to be ejected from the power supply. Does this sound silly? No it isn't because there is a large transformer in the supply which can deliver very high currents in the event of a wiring fault or malfunctioning component. For this reason, go back and check all your wiring very carefully against the wiring diagrams. When you are satisfied that everything is correct, install the two fuses, switch off power switch S1 and plug the mains lead into the wall. Connect a multimeter to the output terminals of the supply, set to read up to 20VDC. Now apply power. The DC output voltage should increase slowly up to The controller PC board can now be secured in position and the Triac bolted to the chassis. Use heatsink compound between the Triac mounting tag and chassis. No mica washer is required here since the Triac specified is one with a fully insulated tab. Overload current setting Fig.10: this is the pattern for the capacitor bank PC board, reproduced here at half size. The full size board measures 180 x 176mm. somewhere around 14V. If there is no voltage or the fuse blows, switch off immediately and unplug the supply from the mains. Be sure to sort out the problem before reconnecting the mains power. If you are getting voltage from the supply, then it is probably operating correctly. To check this, adjust VR1 to see if the voltage at the output can be Sleeve the body of the mains switch with heatshrink tubing after the leads have been attached to prevent accidental contact with the mains. varied. While adjusting VR1, check that the "Output Regulated" LED lights for output voltages between 11.8 and 14.4V. The current overload can be adjusted in one of two ways. The first method simply adjusts the voltage at the wiper of VR2 while the sr,cond method requires a 25A load. A 25A load can be made up using a number of 12V automotive light bulbs, conn ected in parallel to give 350W. When the power supply is loaded by these, trimpot VR2 is adjusted so that the current limit is just above the 350W load. At the onset of limiting, the voltage will fall suddenly. When this point is found, rotate VR2 slightly anticlockwise. To adjust without a load, connect your multimeter between the wiper ofVR2 and ground and adjust VR2 for a reading of 60m V. This will set the current limit to about 30A. Your new power supply is now ready for use. SC UHF HIGH GAIN ANTENNAS Crowbar trip point Disconnect power and temporarily connect a 47kQ resistor across the 47kQ resistor associated with trimpot VR1. This w ill allow the output voltage to be adjusted above 15V. Now rnr:onnr,r.t powr,r and adjust VR1 for an output voltage of 15V. This done, adjust VR3 by rotati ng it slowly clockwise until the crowbar LED just lights. The crowbar LED can be -reset by switching off power and leaving it off for a minute or so. Now, leaving the VR3 trimpot setting as is, reduce the output voltage using VR1 and then slowly increase it to check that the crowbar trip point occurs at 15V. If not, readjust VR3 and check it again. Once the crowbar level has been correctly set, the SCR can be installed on the PC board. Now check that when the output voltage reaches 15V, the crowbar operates by pulling the output voltage to about 1V. The temporary 47kQ resistor can now be removed and the output voltage reset to give 13.5V with no load. antenna existing systems. triangula powder coated receiving elements ensures excellent UHF reception compared to other UHF antennas of similar size and price. Two models are available: the TVA 14 for Band Four and the TVA 15 /or Band Five UHF reception. Both models are supplied with back reflectors to prevent ghosting as well as a waterproof entry box designed to accept 75 ohm coaxial cable without the need for addittional baluns. They also have predrilled holes for securing the tilt adjustable metal mounting bracket in either a horizontal or vertical position. Imported and distributed by: ARISTA. ELECTRONICS Available through the following retailers: Bernys. Bridgepoint. Military Road. Mosman. 2088. NSW. (02) 969 1966. Ritronics. 56 Renver Rd. Clayton. Victoria. 3168. (03) 543 2166. JUNE 1991 73 COMPUTER BITS BY JENNIFER BONNITCHA Configuring your computer using the keyboard enhancers This month, we continue our tour through the ANSI.SYS driver and look at ways to make typing easier using the keyboard enhancers. A couple of sample batch files are included for you to try. .In addition to changing screen colours and cursor location, ANSI.SYS, in conjunction with other DOS functions, ·enables you to customise the keyboard for your convenience. You can reprogram some of your keys to type commands or phrases. You could define any of the ASCII (standard) keys or the ex-tended keyboard keys (Fl-FlO , Home, End and so on) to edit the current line, or recall, edit and enter a previous command line. MS-DOS function keys MS-DOS has a special set of editing keys which enable you to type the same sequences of keys repeatedly, because the most recently typed command line is automatically placed in a special storage area called a template. When you use the template and the special editing keys , you can take advantage of the following features: • repeat a command instantly by pressing just two keys; • correct a mistake at the command line by editing rather than re-typing the entire line; • edit and execute a command line similar to the previous one with a minimum of effort. When you type a command and press the Enter key, MS-DOS automatically sends it to the command processor (COMMAND.COM) for execution. 74 SILICON CHIP At the same time, MS-DOS also sends a copy of this command to the template. You can then recall or modify the command by using the MS-DOS special editing keys. The standard DOS editing keys are: Fl - Copies the next character from the template (previous line) to the current command line. The right arrow key performs the same function. F2 - Copies all characters from the previous command line, up to but not including the character typed from the template, to the current command line. F3 • Copies all remaining characters from the template to the current command line. Del • Skips over (does not copy) a character from the template. F4 - Skips over (does not copy) the characters in the template up to the character specified. Esc - Cancels the current command line and leaves the template unchanged. F5 - Makes the new line the new template. F6 - Produces the end of file marker AZ (Ctrl Z) Backspace - Deletes the previous character from the command line. The left arrow key performs the same function. Other than the Backspace and En- ter keys, the F5 and F3 keys are probably the most widely used. If you reassign the six special function keys (covered a little later), you lose their editing functions. DIR TEST.BAT displays the directory information for TEST.BAT and the command is saved to the template. To repeat the command, press F3 and MS-DOS repeats the entire command on the screen. Press Enter to continue. F2 B displays the information from the previous template up to the specified character, B. Note that F2 does nothing until you type the character you want MS-DOS to copy up to. Type the asterisk (*) then press Enter. You can mix and match the Function key and Insert/Delete operations; eg: F2. Ins 5 F3 F2 5 Del F3 The first command copies the information from the previous template (F2) up to the specified character (.), activates Insert mode (Ins) , adds the number 5 to the template and continues the copy to the end of the line (F3). The second command once again copies up to (F2) a specified character (5), deletes the current character (Del) then continues the copy to the end of the line (F3). You can use the Function keys to go.ad advantage when cleaning up your directories. Before issuing a multiple DEL command, it is a good idea to see a directory listing of the files you want to delete. For example: DIR *.RPT DEL F3 The first command displays all the RPT files in the current directory while SERVICE IS THE DIFFERENCE MOUSE/ JOYSTICK 3 Button, MOUSE Microsoft or mouse system compatible 200dpi resolution BARGAIN PRICE $39.95 $35.00 3 Button JOYSTICK BRAND NAME 360K 5.25" AND 720K 3.5" DISK DRIVES 3 MONTHS WARRANTY e 1 FOR$69e2FOR$120e3FOR$165e4FOR$200 HURRY LIMITED STOCKS NEW PRODUCT METAL KEYBOARD DRAWER Standard Features: Fully VGA/EGA/CGA/MDA compatible LCD screen with CCFT backlit for up to 16 grey scales Supports auto map 256VGA colours to 32 grey shades 80C286 -16MHz with zero wait state 1Mb memory expandable to 8Mb Built-in 40Mb 3.5" disk drive 1.44Mb 3.5" floppy drive 5.25" external floppy drive port Built-in Nicad battery and. 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The simple explanation is that Ctrl C is position sensitive while Ctrl Break is not. Reassigning the keyboard Just as you can design screen attributes, you can reassign a key operaCtrl C - Aborts the current command. tion. Each of the 10 function keys may Ctrl Break (front face of the PAUSE or be used alone or in conjunction with SCROLL LOCK key) performs a similar the Ctrl, Alt and Shift keys . Table 1 shows the details. function. Ctrl S - Suspends output display on The ability to reassign key comthe screen. Press · Ctrl S again to . mands means that you can make almost any key combination type ·alresume. The PAUSE key on the 101 most any sequence of characters. If keyboard performs the same function; you frequently use a specific key sepress any key to resume. Ctrl C is recognised by DOS rou- quence, you can assign the string of tines, while Ctrl Break is recognised characters to a certain key. The actual by ROM BIOS keyboard routines. The business of reassigning the keys is an effect of the two may not always be easy process, similar to changing the screen colours. Once again the the same and one may work when the other doesn't. Whenever you press a ANSI.SYS device driver must be installed in the CONFIG.SYS file for the key, the keyboard handler from ROM BIOS generates a hardware interrupt reassignment to work. which is generally deferred until DOS Just as the screen attributes use a special symbol for the Esc key ($e) is ready. Certain keystrokes, such as Ctrl Alt Del and Ctrl Break are procand continue with the left bracket([), essed immediately. When Ctrl Break you can reassign the function keys is detected, the keyboard routine that using the ANSI command: signals interrupt 1Bh is invoked. ESC[#;# ... ;#p The keyboard routine does not do or anything special if Ctrl C is detected ESC[#;"string";p and the keystrokes are left in the keyYou can think of keyboard reassignboard buffer for DOS to process in Control character effect ment as a kind of DOS macro operation. If you frequently change to a particular directory, you could use ANSI.SYS to assign the command to a function key. The first ASCII code (the first#) defines which key or keystrokes (such as a CTRL key combination) are being reassigned. The remaining (#) or characters within the "string" are the replacement characters typed when that key or keystroke combination is pressed. You could use the keyboard reassignment capabilities to automatically type a command such as: ESC[0;68;"dir/p";13p or PROMPT $e[0;68;"dir/p";13p The above command assigns the DIR/P command to function key 10 (reassignment code 68) . ESC[ or $e[ tells DOS that an ANSI command is being entered while the O (zero) tells DOS that the key to be redefined is part of the extended keyboard. If the first code is O (zero) or 224, DOS assumes that an extended key or Enhanced Keyboard extended key will be used - this is the more usual goal rather than a standard key reassignment. The next number, 68, is the redefinition code for the Fl Okey while the string in quotes "dir/p" is the text of the command. Finally, code 13 is the ENTER key code - if you omit the code, you need to press the Enter key yourself to execute the command. The last character in a key redefinition is always lowercase "p", just as the last character in the screen redefinition is "m". TABLE 1 Function Redefinition Keycode Shift Function Redefinition Keycode Ctrl Function Redefinition Keycode Function Alt Redefinition Keycode F1 59 F1 84 F1 ·94 F1 104 F2 F2 85 F2 95 F2 105 F3 60 61 F3 F3 96 F3 106 F4 62 F4 86 $7 F4 97 F4 107 F5 63 F5 88 F5 98 F5 108 F6 64 F6 89 F6 99 F6 109 F7 65 F7 90 F7 100 F7 110 F8 66 F8 91 F8 101 F8 111 F9 67 92 F9 102 F9 112 F10 68 F9 F10 93 F10 103 F10 113 76 SILICON CHIP You can assign up to 128 characters to a single key. If you redefine several keys you can either create a batch file to automate the reassignment, or include the code in your AUTOEXEC.BAT file. Sometimes you may want to include an Enter, space or double quotation mark within the key reassignment. Since ANSI does not recognise these characters, within a string, you need to use the appropriate numeric code: Enter 13 Space 32 Double quote mark 34 Supposing you wanted to assign the message "This is a test" to the F10 key, you could use the following: ESC[0;68;34;"This";32;"is ";32 ;"a";32;"test";34 ;13p PRICE BREAKERS FROM SHERIDANS DATA MODEM 600/1200 Telecom Modem made by G.E.C . Features: Auto/Manual answer Auto answer only 1200 fixed control via V24 interface Control: A signal from the ring current detector is used to initiate a timing sequence in which the modem is connected to the line These are BRAND NEW. ONLY $59.95ea ARLEC CAR ALARM Features: Red warning light, 3 minute siren operation , exit & entry delay, auto ignition cutout and bonneVboot protection . Easy to install DONT'PA Y $119.00 You assign a key its original code value in order to reset it. A useful feature of the key redefinition process is that the reassignment requests are cumulative - you can issue any number and they accumulate. Each key retains its new definition while ever you are at the DOS prompt level. Note that some programs reset the function key definitions when loaded. If you reassign the keys and start WordPerfect, for example, the WordPerfect function keys work as normal. However, when you exit to DOS, your key reassignments will still function. You could even assign graphic characters to function keys such as: 12 Volt 15AH Sealed Lead Acid . Charge Rate: 14.5 - 15V <at> 3.75A or 13.5 -13.BV at any current for standby use ESC[0;68;"<Alt 201>"p HALF PRICE ONLY $$49.00 This command assigns the double-line , top left box corner to function key F10. Where <Alt 201> appears in the sequence, hold down the ALT key and type 201 on the numeric keypad then release the ALT key and type the remainder of the command. Custom menu system You could really jazz-up your standard computer by including a custom menu system using the screen control, keyboard reassignment and Prompt command capabilities. Here's something simple to try: PROMPT $e[H $e[1m Directory-Fi $e[8C Lotus-F2 $e[8C Word Processing-F3 $e[24;1H $e[25;1H PRESS REQUIRED KEY $e[0m $e[K Your screen should display three messages at the top of the screen and a message at the bottom of the screen. Include the prompt command in a batch file such as the one following , together with the appropriate key reassignments and away you go! <at>ECHO OFF CLS PROMPT $e0;59;"dir/p";13p PROMPT $e0;60;"cd\lotus";13p$e[0;60 ;"lotus";13p PROMPT $e0;61;"cd\wp51 ";13p$e[0 ;61; "wp ";13p Include the prompt from above at this point CLS While DOS is dominant, Windows is rapidly gaining wide acceptance. Therefore, for the next couple of months, we will take a look at Microsoft's Windows 3.0 fro m installation and customisation , through to tips and tricks to help you get the best from your computer. SC BRAND NEW ONLY $59.00ea BU205 SOLDERING IRON STANO 1500V 2.5A Replaces BU208 Your average iron stand but without your average high price. Till stocks last ONLY $8.S0ea. ONLY $1.50 YUASA RECHARGABLE BATTERY VIDEO SENDER UHF Channel 30. Sends signal up to 30 metresCould be used on Audio & TV. Normally $89.95 NOW $45.00 TRANSISTOR DATA BOOK Features all the latest Japanese & European transistors. Up-to-Date, no home should be without one .50% off Normal Price ONLY $14.95 CAPACITOR 25pf 30KV Gas VC 25 - 20 $199.00 FORCED AIR COOLED TRIODE '1,q These are a quality triode and valued at nearly double the asking price. Spee sheets are available. Their type number is r. 3J/170E. Rated at 4KW "- BARGAIN PRICED AT $999.00 , · Sheridan's are beginning to import a range of TV/Video spare parts. Please send your name & address for your copy of the catalogue. I ViB I_ SHERIDAN ELECTRONICS, 328 ELIZABETH ST, _ (Cnr Kippax St. opp. Central Station & Dental Hospital) SURRY HILLS, Nsw; 2010 TELEPHONE: (02) 281 7727 SHOP HOURS: MON - FRI SAT 9 00am - 5.30pm 9.30am - 12.00pm ] LIN E 1991 77 VINTAGE RADIO By JOHN HILL The 4-valve Howard receiver Last month, I mentioned that I had bought an old Howard, a mains powered 4-valve reaction set from the early 1930s. The Howard is a mediumsized console model of relatively square proportions which stands on turned legs. It was the latter feature that prompted me to buy this particular receiver. Console rec eiver cabinets with turned legs are comparatively rare. Turned legs were in for only a short period and were popular around 1930, give or take two or three years. Unfortunately, cabinets mounted on turned legs, particularly long turned legs, are relatively weak and the legs do not give rigid support. Shifting the set incorrectly can damage or loosen the legs and the cabinet can become quite rickety as a result. It was perhaps because of these problems, as well as the additional cost of turned legs, that cabinet makers turned away from this style to the legless console models of the mid-1930s onwards. However, regardless of their shortcomings, console radio cabinets with turned legs have particular appeal and some are quite elegant to say the least. Whether weak, impractical or otherwise, turned legs look great and any receiver with this style of cabinet is a highly collectable item. It was the turned legs on the Howard that per- The cabinet has been knocked around a fair bit and will require a considerable effort to restore. Fortunately, the damage is all repairable. 78 SILICON CHIP The Howard cabinet is fairly typical of the consoles made around 1930, although the turned legs are quite rare. These legs and the fretwork speaker grill give the radio a certain amount of charm . suaded me to buy it and it is the first complete set I have been able to obtain with this style of cabinet. Unfortunate ly the Howard's cabinet was only in fair condition. It has received many knocks over the years and some of the veneer has chipped away at the edges. Someone has also attempted a half-hearted refurbishing job which was far from professional. Nevertheless, the cabinet is restorable although it will require more than the normal amount of work. The circuit is of simple design, even for a regenerative receiver, and consists of a detector followed by two audio stages. The first one is resistance/capacitor coupled, while the conventional shield but the set works just as well without it. Although the receiver was in working order, there were a few major items that needed attention. The volume control was very noisy, the dial cord was slipping, the detector and rectifier valves were not the original types , and there was the usual dust, rust and lack-lustre appearance of the chassis in general. There were numerous oth er incidentals that also needed looking into. The repairs all seemed to be straightforward enough but little did I know what was in store. Broken dial drum The chassis cleaned up surprisingly well for an old-timer. Note the cast aluminium shields over the power and audio transformers. A shield was also fitted over the detector valve, although the set works just as well without it. This end view of the chassis shows three of the valves (from left to right): 245 output, 227 first audio & 224 detector (in shield). The fourth valve in the set is the 1651 rectifier (behind the audio transformer at top left). other is transformer coupled . The output valve (a 245 triode) drives an 8inch electrodynamic loudsp eaker. Not all of the valve sockets had the right valves in them but more about that later. Reaction control A l00pF variable capacitor is us ed as a reaction control and the audio from the detector is fed to the first audio valve via a 0.5MQ potentiometer. This volume pot, when used in conjunction with the reaction cap- aci tor, gives good vo lume control regardless as to whether th e set is tuned to strong or weak signals. Th ere are also three aerial tappings , so the effect of local station swamping can be minimised by se lecting the appropriate aerial tap and reaction/volume control settings. Component shi elding on the Howard is elaborate - even where it is probably not required. The power transformer is encased in a cast aluminium cover, as is the audio transforme r. The detector va lve has a more First , the di ecast dial drum had a buckle in it. However, it could not be removed unless the tuning capacitor was also removed. This was essential anyway because the capacitor was a plain bearing type and it nee ded attention in the bearing department. With the dial drum free from th e capacitor, the reason for the buckl e was fairly obvious: the centre had broken out at some time and had be en cemented back into place with epoxy. The joint was broken again, reglued with superglue and reinforced with a steel plate. This repair was much stronger than before but the drum stil l ran with a wobble because the hole in th e centre had nev er been drilled straight in the first place. Not to be beaten , I decided to set the drum up in my lath e, re-bush th e centre and drill it out again so that th e new hole was both concentric and square to the face of th e drum. The chuck jaws had hardly tou ched the dial drum when it fell into th e tray of the machine in four pieces. Th ey don't call old diecast aluminium "muck metal" for nothing. Modern epoxy resins are very us eful adhesives and th e four pi eces were all glu ed back together again - and the damn thing still runs with a wobbl e ! Th e tuning capaci tor was much easier to fix. The loose front bea ring was adjustable and a good fit on th e shaft was obtained in no tim e at al l. A piece of thin cardboard was also used to pack th e front bearing so th at the plates were more centra lly positioned. th e cardboard a ll owing for the wear in the thrust bearing. By the way. tuning capac itors am much easier to cl ean and 1,,vork on when they aro removed from the chassis. The chassis is also much eas im to ] U,\J E 1991 79 rectifier socket with a low -value wirewound resistor (0.6Q - 2 x 1.2n in parallel) to drop the 5-volt filament supply down to about four volts. The big old 1651 looks great and is a better substitute for the 280 than the 80GT. Incidentally, an 80 still works reasonably well despite the lower filament voltage. Several other parts needed attention underneath the chassis and the first job was to replace the volume control potentiometer. The reaction capacitor was also cleaned up and a drop of oil on its spindle made it much smoother to turn. Dangerous aerial The rear of the chassis carries sockets for the phono pickup (left) and for the aerial taps (right). There are only three aerial taps - the other two holes once accommodated an external aerial & the mains aerial plug. clean and paint while the capacitor (and any oth.er components) are removed. This was the case with the Howard and the chassis was rubbed down and painted while the capacitor was on the workbench. Ring-in valves Cleaning down the chassis revealed the original valve markings that were stencilled on when the receiver was made. The detector socket was supposed to have a 224 valve but an F242 had been fitted at some stage instead. This valve was so weak it tested at only 15%, compared with the 80% of the 224 that replaced it. Although supposedly the wrong valve, the F242 looked exactly the same , both internally and externally, as the 224 valve and was no do\lbt a satisfactory substitute apart from the poor emission problem. The 227 (first audio) and 245 (output) valves both tested OK, as did the 80GT rectifier. Using a GT valve in an ancient regenerative set looks terrible - even if it does work OK. The originally specified 280 rectifier with its bulbous shaped glass envelope looks far more appropriate but, unfortunately, I did not have a spare one to use in the Howard. However, in my "odd valves" box there were a couple of 1651 valves which are similar rectifiers in shape and performance to the old 280. The only real difference is that they are 4volt valves whereas the 280 was a 5volt type. One of these 1651s was fitted to the At one stage, the loudspeaker refused to work and the problem was traced to an open circuit speaker transformer. Once it was replaced, the problem was solved. The 8-inch electrodynamic loudspeaker works quite well for its age. 80 SILICON CHIP One particular capacitor also seemed to be in an odd place and after checking it out, I decided to remove it from the receiver altogether. It was the mains aerial capacitor. The purpose of a mains aerial is to use the power supply wiring as an aerial and there was a connection from the primary side of the power transformer to an aerial plug, with only an ancient capacitor in between to isolate the circuit from the mains. It's a dangerous arrangement and this is the second such aerial I have removed from an old receiver. The set's original electrolytics had long been replaced and these too were now in need of replacement. Replacing electrolytics is a fairly standard procedure with radios as old as the Howard. Checking out the only two carbon resistors in the receiver revealed that they had both gone high with age. The worst one was the 2MQ grid leak resistor - it had risen to 6.5MQ Oddly enough, the replacement resistor seemed to make little or no difference to the set's performance. There was still another resistor to check out and that was the high tension voltage divider. Past experience has shown that these wirewound voltage dividers can give a lot of trouble when the contact areas at the various taps no longer make a good connection. As far as I am concerned, it is standard procedure to remove each tap and thoroughly clean it and the resistor wire before reassembling it again. Cleaning the resistor taps prevents the poor performance and high tension crackles that can be caused by dirty, ill-fitting connections. Resurrection Radio Vintage Wireless Specialists Repairs - Restoration - Sales Our skilled technicians offer QUALITY repairs and restoration. We also have a large stock of Bakelite and Timber radios fully restored and for SALE. This underneath view shows the high tension voltage divider, coil, reaction capacitor and volume control. Parts are available for the enthusiasts including over 900 valve types, high voltage capacitors, transformers, dial glasses, knobs, grille cloth etc. Circuit diagrams for most Australian makes and models. Send SAE for our catalogue. WANTED - Valves , Radios , etc . purchased for CASH Call in to our Showroom at: 51 Chapel Street, Windsor,Vic 3181 PO Box 1116 Telephone: (03) 529 5639 The dial drum broke into three separate pieces and was repaired using Superglue. They don't call diecast aluminium "muck metal" for nothing. Underneath the chassis, there are three initialled dates pencilled in (all within a week of each other), with the last one being the 21/3/32. It would appear as though these were put there by inspectors at the Howard factory when the set was made. These dates are interesting because one would expect that only TRF and superhet receivers were being made in 1932. However, the cheap er regen erative sets were also still being mad e at the time. It must be remembered that 1932 was in the depression years and not many could afford a top of the range superhet receiver. Perhaps there was a greater demand for cheap er radios? Crook loudspeaker? The Howard 's loudsp eaker presented an unusual problem because it had decided to stop working some time between when it was removed from the cabinet and when it was connected to the restored chassi s. A check with the multimeter soon revealed that the primary of the speaker transformer had become open and the transformer needed replacing. Once this simple repair was done the set burst into life and worked quite well. One odd aspect of these simple regenerative receivers is that there is nothing in them to align. In a superhet receiver, the intermediate frequency (IF) transformers require alignment , as do the oscillator and aerial circuits. A simple reaction set requires no such adjustments - it just goes and that's that! There is nothing to tune but th e stations. At this stage of the story, the Howard is as good as it has ever been and is working very well considering its age and antiquated regenerative circuit. However, the chassis and speaker will . have to remain on the bench for a whil e until I find time to restore the cabinet, which will be quite a big job. When that task has been completed, the set will join the rest of my co llection and will have the distinction of being the only one of my consoles with turned legs and a regenerative circuit. A good vintage radio collection needs a wide variety of receivers to make it int eresting and the Howard certainly is an interesting old set. SC JUNE 1991 81 DIGITAL MULTI METER HC -4510 DISPLAY:41/2 DIGIT BASIC ACCURACY: 0.5% DC V DC DC AC AC VOLTAGE: 0-1000V CURRENT: 0-10A VOLTAGE: 0-750V CURRENT: 0-10A RESISTANCE: 0-20M OHMS CONTINUITY TEST, DIODE TEST DATA HOLD 013030 ........... RRP $149.95 20 MHz DUAL TRACE OSCILLOSCOPE CTR DISPLAY:. 150 mm rectangular VERTIACAL DEFLECTION: • Deflection Factor: 5mV to 20V / Div on 12 ranges in 1-2-5 step with fine NOW $129.95 ,-u control • Bandwidth DC: DC to 20 MHz (-3dB) AC: 10Hz to 20 MHz (-3dB) • Operating modes CH-A, CH-B, DUAL aad ADD (ALT/CHOP L202 only) • Chop Frequency: 200 KHz Approx. • Channel separation: Better than 60dB at 1KHz DISPLAY: 3 1/2 DIGIT BASIC ACCURACY: 0.5% DC DC VOLTAGE: D-1000V DC CURRENT: 0-10A AC VOLTAGE: 0-750V AC CURRENT: 0-10A RESISTANCE: 0-20M OHMS CONTINUITY TEST, DIODE TEST TIME BASE . Type: Automatic & normal triggered in automatic mode, sweep is obtained without input signal • Sweep Time: 0.2m Sec to 0.5 Sec/ Div on ranges in 1-2-5 step with fine control and X-Y. • Magnifier: X5 at all times. CAO Probe =====- J to suit TRIGGERING NOW ONLY $29.95 Ca t. 0 12201 • Sensitivity lnt: 1 Div or more Ext: 1Vp-p or more. • Source: INT, CH-B, LINE or EXT • Triggering Level: Positjve and Negetive, continuously variable level; Pull for Auto. • Sync: AC, HF Rej, TV (each +or-) at TV Sync. TV-H (line) and (frame) ·sync are switched automatically by SWEEP TIME/Oiv switch. HORIZONTAL DEFLECTION • Deflection factor: 5mV to 20V/ Div on 12 ranges in 1-2-5 step with fine control • Frequency response: DC to MHz (-3dB) • Max Input Voltage: 300V DC + AC Peak of 600V p-p • X-Y operation: X-Y mode is selected by SWEEP TIME/ Div switch. • Intensity Modulation Z Axis: TTL Level (3Vp-p- 50V) + bright, - dark OTHER SPECS: • Weight: 7Kg Approx • Dimensions: 162 (H) x 294(W) x 352(0)mm. 013010 .................... RRP $119.95 DC VOLTAGE: 0-1000V DC CURRENT: 0-10A AC VOLTAGE: 0-750V RESISTANCE: 0-20M OHMS CONTINUITY TEST, DIODE TEST, DATA HOLD, TR HFE GAIN, AUTO RANGE DMM WITH BAR GRAPH ► ~~ / 013040 ......._ .... ...... .. .. RRP $99.95 NOW $89.95 __ __ ___ __ _ _ __;;;_..,.__-I O12105 ............. ............. RRP $750 NOW $695 MULTI METER HC-3500T 100 MHz 3 CHANNEL 8 TRACE MODEL 5510 This instrument meets the customers needs in quality of performance, efficiency, function, design, and cost! Being rugged, highly reliable and a multi-purpose 3. channel, 8 trace oscilloscope with a 6 inch domed mesh type 14kV post deflection acceleration cathode-ray tube and with a fine red internal graticule. FEATURES: • Compactness, lightweight, ruggedness and siniple design. • The diecast frame provides compactness lightweight and ruggedness. • Easy Operation light torque lever switches and pushbutton switches are used . • High Brightness CTR, high acceleration voltage and high beam efficiency of the 150mm rectangular CTR ensures a bright high speedsweep observation • Multi mode display system CH1, CH2, CH3, Add any combinstion or all the channels may be viewed simultaniously. Maximum 8 trace displaying is possible with the ALT sweep function . • High sensitivity and wide frequency bandwidth. The maximum vertical sensitivity is 1 mV/DIV (when x 5 MAG)at 20 MHz or greater 3dB and mV/DIV at 100 MHz or greater -3dB. 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RS232· 2 way .. .. ..... ... .... .... $39 AS232· 4 way... ......... $59 RS232- X over ... ........ .$69 AS232· 2 way auto .. .. ....... .$69 Centronics- 2 way ... ... .. ...... $49 Centro nics- 4 way ... .........$69 Cenlronics• X over ....... ... ..$69 Centronics- 2 way auto . .... $79 • DE 9P 9 pin plug P1 2 166 $ 2.95 S 2.50 $ 2.00 . DA 15P 15 pin plug P 121 70 Z10143(Y) ... .$0.20 $0 .15 $0.12 LEDS 1----------e---t SIMMS CITY: 48 A' BECKETT ST, MEL BOURNE W . ( NORTHCOTE: 4 2 5 HIGH ST, NO RT HCOTE :Z ~ SVD NEV: 74 PARRA MATIA RD, STANMORE ~ ..._, o,o, ~" " 1.951.80 1.95 1.80 2.95 2.75 2.95 2. 70 3.95 3.50 3.95 3.50 40 Din 4.95 4.50 Description .... ...... $ 2114 ................ $6.20 2716 ........... ... $12.50 2732-200.... .... $6.25 2764-250 ........ $8.115 27128 .............. $8.00 27256-250 .. .. .. .$9.50 27512-250 .. ... $1 4.95 27-lMEG ....... $29.50 27C64-200NS . $8.95 27C128 ........ . $12.50 27C256/ 250NS ........ .. . $15 .50 27C512 ......... $22.50 27C 1 MEG .... $34.50 4164-10 ........ .. $4 .gij 4464-10 .......... $5.50 4464-08 ........... $5.g() 4 1256-10......... $4 .96 4 1256-08......... $5.50 44256-10 ....... $13 .95 44256-08 ....... $14 .95 44256-07 ....... $15. 95 6116 ............. $5 .50 6264LP-10 .. $ 19 .95 62256LP-10 .. $39.95 8088 .... .. ....... $ 12.50 lM-10 ........... . $ 13.95 lM-08 .......... .. $14.gij Z10141(GJ ... $0.20 S0.25 S0.12 SWITCHES wire wrap sockets are 16pln 18 pin 20 pin 22pin 24 pin 28 pin 111-88 100+ Z10140(R) .... $0.15 $0.12 S0.10 RECTANGULAR DATA ~ IC SOCKET S ,,,,,,,, , . I- 35e These quality 3 level $3.95 $2.95 • ~ l it ~: WIRE WRAP 10+ , .9 ~•~:~g '1 fTT?" '! l ! 1 1 1-9 10+ 100 + P10U62 $3.50 $2.95 $2.50 . , a: f'•~' f◄ lI 1·9 22': i,;m,m, information carriers aS' they can be either pulsed or used in a PIN CHASSIS Oimmens ions :115x32x44mm Weigh! : 220grams 1~ 15e 18t 1-6e 25(: 1 - - - - - - - - - - - 1 A10452 ...... ......... $99 L 19990..... $3.95 $2.95 CANNON TYPE 3 ~]?; ~i ;: ::~:. ·.: ~ p 10575 40 pin .... ~ water level detectors , burglar alarms , motion detectors and ·Transmitter ID / 14 pin . ... 2()e 16 pin . ... 2Qe 18 pin .... 30e 20 pin .... lSe 22 pin .... 3..Se continues wave mode . :z ii: : 40e 10.eG 100. 8 pin ......1se 12e 10t ~~~~;~ These units can't be heard so are ideal for TV remote control 's , SOLDERLESS TWIST ON PLUG '- < Designed to transmit at 40kHz (L 19990) and (L 19991 )with up to 20V 1/P on the transmitter. BNC 1-9 P , ., ULTRASONIC BNC CRIMP PLUG 30e 2Se 30e 26e MICROPHONE SPECS : Transmilling Frequency : 37 .1MHz Transmitting system : Crystal oscillation. Microphone : Elecftet condenser Power supply :9V battery Range : 300 feet in open field RECIEVER SPECS : Receiver freq : 37 .1MHz O u!put level : 37mV(max) Receiving sys : Super crystal o scillation p y b v~~:es~~~~rol : Led Cat. No. Descript ion DB25 CONNECTOR . SPECIALS ===t-►- ~~ QUALITY 3MM LEDS 1-8 RECIEVER Save• small fortune on these " Direct Import" low prollle le sockets ! PCB mounting solder ta il. All lin plsled phosphor bronze or berrylllum and dual wipe lot reliability. P10550 P10560 P10565 PlD567 P10568 PtOS69 ===1.,; ( C RYSTAL LOCKED WIRELESS MICROPHONE & LOW PROFILE IC SOCKETS improve s heat tran s fer from the device to the LEDS ! E ffil Heatsink compound is BNC MALE PLUG 1: . IC SQ_CKETS ' HEATSINK COMPOUND ,.,. A . ., __J::,) -..,~... ·, All sales tax exempt orders and wholesale inquiries to : ~ITRONICS WHOLE SAL E 56 Renver Road, Clayton Phone 103) 543 21 66 13 hnes 1 Fax 03 543 2648 Errors and om1ss,ons excepled Pnces and spec1hcat1ons subject to change ,01,1· PC · •1 · .,, . -'' l! ' "9•ste<1!<1 ll,IOllm1, • sn l ,.,1. n,uon,1 8u S"'CS\ MK/'l.~ s · ~ t ,s ,1 ,119s11,ec 1o ~ r1,· 0enotes ,..g,s1e,N'l •1,1dma,'l, s o' tt,e,, ,e _ . 1.,.1!' OWf>el ~ I ... ,. , I I PRODUCT SHOWCASE I Multi-channel mixer from Arista This AVM3 multi-channel mixer is ideal for both professional and amateur camera operators. It has audio adding and mixing facilities for add ing voice-overs and music to existing recordings. It's compatible with all video formats and inputs can be selected from CD players, camcorders, VCRs, tuners and microphones . A monitor function allows you to hear the mix through headphones. It also features left and right VU meters and the unit can be operated from either a 9V battery or a plug pack. The cost of the unit is $169 from David Reid Electronics, 127 York St, Sydne~Phone(02) 2671385 . bles, terminal blocks, mounting plates and a pair of headphones for $84.95. For more details, contact Philips Accessories on (02) 742 8437. Headphone adaptor for car radios Do you find it distracting when others in the car want to listen to the stereo system while you just want to concentrate on the road? Philips can eliminate this problem with their new Car Headphone Adaptor which connects straight to the speaker wiring. Because of its convenient size, the adaptor can sit on the parcel shelf or between the front seats. It can switch PC suppliers announce merger the car speakers in and out and has two independent volume controls. The kit comes complete with ea- Compact 100W 12VDC-240VAC inverter If you've been looking for a compact car voltage inverter but you're not keen to build one of the kits available, then this compact unit from Jaycar is a handy solution. Measuring only 120 95 x 35mm, it will supply 100W at 240VAC, enough to power a portable TV and VCR. It features electronic circuit protection and low-battery shutdown (below 10V). It's also capable of providing 200W of peak power to Cellular radio lightning protector x 84 SILICON CHIP Board Solutions and Electronic Solutions have announced their merger, effective on May 1st, 1990. The strategy for the new company, Electronic Solutions, is to provide a larger array of high-quality low-cost PCs and addon cards. For more information on any of their products, please contact Jeremy Smith on (02) 906 6666. start difficult loads such as motors and lamps, yet its quiescent current is only 60mA. The unit retails for $189.50 and is available from any Jaycar Electronics store. The aerials of cellular radio base stations are prime targets for lightning strikes, which are quite capable of destroying the expensive equipment on the other end. Huber & Suhner have come up with a lightning protector specifically designed for those base stations transmitting and receiving signals between 797MHz and 1016MHz. It 's an in-line quarter-wave shorting stub design which produces no ELECTRONICS WORLD Reproduction vintage radios There's nothing like sitting back and relaxing to the sounds-of an old but lovingly-restored virttage radio. However, they can be hard to get and involve a lot of work, so Resurrection Radio has come up with an alternative - reproduction models with old fashioned looks but today's performance. The Model 411 is an AM/FM solid-state unit with the added extra of a built-in cassette player. Frequency reception ranges are 530-1610kHz for AM and 88108MHz for FM; with sensitivities of 45dBm AM and lOdBm FM. The price for the Model 411 is a very reasonable $199 and it comes intermodulation effects, is waterproof, easy to mount using common brackets or clamps and has an impedance match of 50Q. For further details, contact Huber & Suhner (Australia) Pty Ltd, Unit 1, 1 Vuko Place, Warriewood, NSW 2102. Phone (02) 913 1544. 9-channel data recorder This 9-channel multi-purpose data recorder is suitable for recording all sorts of measurements from high to Hobbyist Tacho/Multimeter for model aeroplane enthusiasts - 3.5 Digit display . - Tach2 Propellor 100 - 60,000rpm 3 Propeller 100 - 40,000 rpm 4 Propeller 100 - 30,000 rpm - DCV (0-2, 0-20 volts) - Continuity (0 - 2KQ ) Now $99.95 IDEAL batteries for glowplug with a 5-year guarantee. For further information, contact Resurrection Radio, 51 Chapel St, Windsor, 3181. Phone (03) 529 5639. low speed. The T-938 operates using 216mm wide chart paper and can place any number of channels between 1 and 9 across the paper to give a divided display. The sample speed can be selected between lµs and one hour, thus accommodating slow-changing temperature measurements, as well as noise and vibration measurements. Input modules are available for both analog and digital inputs. The unit is also fully portable with a built-in DC supply and shoulder carry strap. For futher information, contact Anitech Pty Ltd, 52/2 Railway Pde, Lidcombe, NSW 2141. Phone (02) 749 1244. 2 Volt 2.5Ahr D cell$ 7.95 2 Volt 5.0Ahr X cell $11.95 Powersonic sealed lead acid rechargable betteries $22.95 $24.95 $27.95 $31.95 $32.95 $35.95 $15.95 $14.50 $15.95 $18.00 $21.95 $25.00 $29.95 12 volt 0.7Ahr 12 volt 1 .2Ahr 12 volt 1.9Ahr 12 volt 3.2Ahr 12 volt 4.0Ahr 12 volt 6.5Ahr 6 volt 0.5Ahr 6 volt 1.0Ahr 6 volt 1.2Ahr 6 volt 3.0Ahr 6 volt 6.5Ahr 6 volt 8.0Ahr 6 volt 10.0Ahr Arlec remote control door chime $26.95 Piezo siren with backup battery ideal for car alarms $59.95 Digital AM/FM car radio/Cassette $69.95 12 volt cig lighter soldering iron New delay timer from Philips Philips Components has released a new programmable CMOS timer, capable of producing delays of between 100ns and several days . Designated the 74HC5555 and 74HCT5555, the IC contains a 24-stage binary counter, an oscillator, a retriggerable monostable, and power on and master resets. It accepts an external clock signal or operates using an RC network or external crystal. Positive and negative edge triggering are also available. The output drive current is 20mA maximum while the quiescent current is less than 500nA. For further information, contact $ 9.95 NOW OPEN our new: Electronics Disposal Store 27 The Mall Sth. Croydon, Vic, 3136 Telephone: (03) 723 2699 Many great bargains for enthusiasts Mail Orders Welcome Electr.c;>nic World 30 Lacey St, Croydon VIC, 3136. Telephone: Fax: (03)723 3860 (03)723 3094 (03)725 9443 ] UN E 1991 85 Realtime interface for PCs This computer interface system, the RIM-1000, designed in Australia by Novatech Controls, will allow connection of temperature sensors, pH meters, proximity detectors, limit switches, relays and power meters through one of the Philips Components, 34 Waterloo Rd, North Ryde, NSW 2113. Phone (02) 805 4455. Bulk-pack desoldering braid 17 analog or 14 digital inputs. The unit then connects to any computer via the RS-232C serial port. It also has modem facilities, allowing the user to "ring up" remote locations for monitoring and control purposes. For more information, contact Novatech Controls (Aust) Pty Ltd in Melbourne on (03) 645 2377. and with the open construction of the socket, it permits a full view of each solder joint. The Samtec range is available for chip carriers with 28, 32, 44, 52, 68 and 84 leads. For more information, contact NSD Australia toll free on 008 335 623. Transistor and continuity tester new 20-metre length reels. The new pack features a snap lock to ensure the braid is kept out of the atmosphere in a dust-free container. The Tech-Wick Fast braid is also available on 7.5-metre rolls. For more details, contact Scope Laboratories, PO Box 63, Niddrie, Vic 3042. Phone (03) 338 1566. Surface mount PLCC sockets Samtec, through NSD Australia, have realeased a series of PLCC sockets which are precision stamped and have a full pin contact to provide a The Tech-Wick range of desoldering highly reliable socket. braid has been extended to indude The body is made using a liquid economy bulk packs, giving savings_ crystal polymer (LCP) which permits of between 15% and 20% with the high temperature infrared soldering !.E:.,.;. ;r.:~1;:.:.1.~ RCS Radio Pty Ltd is the only company which manufactures and sells every PCB f., front panel published in SILICON CHIP, ETI and EA. 651 Forest Road, Bexley, NSW 2207. Phone (02) 587 3491. 86 S ILICO N CHIP In the field or even on the workbench, the need often arises for a simple transistor checker that doesn't need an instruction manual to figure out. This unit from Jaycar Electronics is compact and easy to use. You can select either transistor or continuity functions with the switch and then use either the four pin socket, which handles all types of transistors, or the two probes for continuity testing. The transistor checker indicates whether or not the test transistor is either NPN , PNP or crook, while the continuity tester has an audible beep as well as a LED indicator. It is available from all Jaycar Electronics stores for $22.95. SC WOOD FOR CHIPS ... WOOD FOR CHIPS ... WOOD FOR CHIPS ... WOOD FOR CHIPS ... WOOD FOR CHIPS .. . WOOD FOR CHIPS . . WOOD FOfi : c LOOK! Take a close look at APPA multimeters. Look familiar? That's because they're sold under diffetent brand names. And that means you :e~ 0 fgu~t-:l ~ ~~'t~~htrt~~~i~:ed model selling at ar.ound $150 more than our price. So you're paying that much extra just for the brand la""bel! Look at the maturw, • Largs high contrast dlsp/'f ThB 96 and 98 havs analog bar graphs too • Colour codsd input tsrmlna/s and function switch tor sasy sstting • Probs storage cl/ps built in tor easy two handsd msasursmsnts • Ths 96 is watsr rwsistancs for Industrial uss • Shockproof for a drop of 1.5ml • Built-in till stand : ~J~f/tg'i4i~~Jf~t and UL1244 standards for safs opsration Mods/93 e 1999 count • Large 20mm high contrast LCD readout • 8 Functions - Vdc, Vac, Ade, Aac, Ohms, Diode. Frequency, Capacitance • 0.5% de accuracy Rangss Vdc 200mV, 2V, 20V, 200V, 1OOOV Vac 200mV, 2V, 20V, 200~0V Ad~l_~ilt· 2mA, 20mA, A, ~ 0 c:, ..,, 0 lJ C) J:: ~ Please ring for wholesale pricing on larger quantities or tax free pricing Aac 200uA 2mA, 20mA, 200mA, 2A, 20A Ohms 2000, 2kQ, 20kQ, 200kQ, 2MQ, 20MQ Frequency 2kHz 20kHz, 200kHz Ca~acitance 2nF, 20nF, 200nF, 2µF, Also~ailable Mods/ 93Twith transistor tester in place of 2A range $142.£0 Mods/ 96 • 3 1/2 digit plus 41 segment analog bar graph • Autoranging or manual selection • 6 functions - Vdc, Vac, Ade, Aac, Ohms, Diode • Water resistant • Data hold • Memoiy offset Gtg~'t:Jmv, 2v, 20v, 200V, 1000v Vac 200mV, 2V, 20V, 200V~OV Ad~l_~ilt• 2mA, 20mA, 2 A, Aagl_°?bt• 2mA, 20mA, 200mA, . Ohms 2000, 2kQ, 20k'1, 200k'1, 2MO. 20MQ $166.80 Model 98 • 3 1/2 digit plus 41 segment analog bar graph • Autoranging or manual selection • 8 Functions - Vdc, Vac, Ade, Aac, Ohms, Diode, Frequency, Capacitance • Data hold • Memory offset Rangss Vdc 200mV, 2V, 20V, 200V, 1000V Vac 200mV, 2V, 20V, 200V~OV Ad~l_~ilt• 2mA, 20mA, 2 A, Aagl_°?bt• 2mA, 20mA, 200mA, Ohms 2000, 2kQ, 20kQ, 200kQ, 2MQ, 20MQ Frequency 2kHz 20kHz, 200kHz Ca~acitance 2nF, 20nF, 200nF, 2µF, OµF $214.80 Mods/ "76 Component Taster Does the things your multimeter doesn't! • Capacitance 200pF to 20uF • Resistance 2000 to 20MQ • Transistor hie and lceo • Diode displays VI at 1mA • LED disr,1ar:s VI at 2Ma and 1OmA : ~~e~as~~~iT¥e:rd 1.SV cells $142 .80 ~ The NEW SCS000A DIC Desoldering Tool. Now fitted wi th SOW heater, NEW Hot air nozzle makes it easier to remove surface mount devices. Price is unchanged at $399 ex tax ($4 78 inc tax} If you're working on surface mount SMli°Reemoeva I Kit. 0 c:, ..,, a lJ C) J:: ~ Squeeky Clean Mains Filters ~ a Provide comprehensive protection for PC's, videos, tv, office equipment etc against surges and interference. Response time is less than 20ns! Peak impulse current is 2500A for 20µs!Clam ps at 250Vrms. 1OA continuous rating. Will not trip earth leakage devices. Made in Australia and fully 0 c:, ..,, 0 lJ <::? a~~~~I~ f~~?bii1i i~'fo ~witched power point $115.00 :.·::•y':.:!" LF-4 has 4 independent filtered , outlets and 10A breaker $250.00 Wsllsr . t"7'1' / , •• . _-- Variable Transformsrs So/dsring ·· ·: Easy way to 'adjusr the mains. Stations • .. 1.2A open $97 .70 WTCPS ·. 2.5A open 1122.20 - -· SA enclosed 159 .60 Transformer powered low voltage 7A enclosed 187.30 soldering station. Features Welrer 13A enclosed 314.65 closed-loop method of controlling maximum tip temperature to protect temperature sensitive components. • Grounded tip protects voltage and current sensitive The latest high-tech w;tt to clean PCB's, switches, watches, drafting 0 • ~g(lfs ~~1~·s steel heater pens - even your dentures! Let the construction millions of tiny cavitation bubbles • Non-burning silicon rubber cord clean the surface 40000 times per e 15 tip sizes. 0.8mm to 6.00mm second. 16Sx90x50mm container • 11secs to recover for 37' C drop holds half a litre and is made of 304 • Choice of tip temperatures stain less steel. Some people are • 315' C/600' F, 370' C/70"F, charging a lot more. 430°C/800' F $137.00 Our's are only $150 Ultrasonic Cleaner (!11121 H!,hl ltM ,p., r choice wi th tho: " """ Oeyl •"' ,,..., 1~m1. or'""" the f ,etl lttler o>I' ,p,r cho ice 11,e [ES( ) ~ . , . ~ i., \ o c"\ ••t<I • Writes cap tu red data di rectlv to disk to allow maximum capture buffer • CRC checksum calculations • Auto-configuration to any of the comms ports 1 to 4 • Time-stamping (absolute and relative) including delta time calcula!ions e Split line DTE ~~s°~~sd!!f~~ytax Send $10 for a demo tsk, refundable on purchase. ~ 0 c:, ..,, a lJ C) J:: 'ii "' ~ c:, ..,, 0 GEOFF WOOD ELECTRONICS PTY LTD 229 Burns Bay Road , (Corner Beatrice St .) ING IN Nsw Lane Cove West, N.S.W. P.O. Box 671 , Lane Cove N.S.W. 2066 Telephone: (02) 428 4111 Fax: (02) 428 5198. 8.30am to 5.00pm Monday to Friday, 8.30am to 12 noon Saturday. Mail Orders add $_5 .00 to cover postal charges. Next day delivery in Sydney add $5.00. \I,...,..,. 0 lJ ~""~~=::: r~--- All prices INCLUDE sales tax. Tax exemption certificates accepted if line value exceeds $10.00. BANKCARD, MASTERCARD, VISA , CHEQUES OR CASH CHEERFULLY ACCEPTED C) J:: 'ii "' AMATEUR RADIO BY GARRY CRATT, VK2YBX Build this active filter & improve your CW reception One parameter of receiver performance that is difficult to achieve is good selectivity. For years, designers have tried a variety of techniques including stagger tuned IF stages, LC filters, cascaded crystal filters, mechanical filters and multipole quartz filters in the quest for the perfect (rectangular) response curve. The compromise required to ensure stable, reproducible filters has always been poor shape factor. The result of imperfect filters in shortwave receivers, in practical terms, is the inability to resolve signals on adjacent channels without interference. Although amateur texts are full of comp lex LC audio filters, which are capable of improving reception by tailoring the audio response, very few simple filters which will do the job have been published. Our design provides a dramatic improvement in the resolution of CW signals and is also quite useful when resolving SSB. The heart of the circuit is the commonly available 741 op amp, which is configured as a multiple feedback bandpass filter. Circuit details Fig. 1 shows the circuit. Bandpass filters provide significant attenuation TP +5V 15k ~-------+--',Mh---0+9V 10 + 16VWl Cl 0.1 o--1------1,.-----1 . 001 I AUDIO INPUT + I I/ TO I HEADPHONES CW FILTER Fig.1 : the circuit consists of a bandpass filter based on a 741 op amp (ICl). Note the unusual bias arrangement. This has been employed so that the op amp runs in starved current mode. 88 SILICON CHIP at very high and very low frequencies and much less attenuation to frequencies within the passband. Some explanation of terms is now appropriate. The "bandwidth" of a filter is defined as the difference between the upper and lower points where the filter response falls and remains below the 3dB peak amplitude. The "centre frequency" is the geometric mean of the upper and lower 3dB cutoff points. The "resonant frequency" of a single pole bandpass filter is the centre frequency of the filter, but this is not half the difference between the upper and lower cutoff frequencies; rather it is the square root of the product of the upper and lower cutoff frequencies. The "fractional bandwidth" is the ratio between the bandwidth and the centre frequency. Our simple 741 op amp bandpass filter has a Q of 20, a gain of 15, and a bandwidth of 35Hz or so. Purists will immediately note that the 741 is not biased in the conventional manner using a voltage divider to obtain a ½Vee reference from the single supply. Instead, the non-inverting input, pin 3, is biased from the OV rail so that the 7 41 is throttled right back to the point where it consumes a lot less than its normal current . This starved current mode means that the cheap old 741 can be economical to run from batteries if required. (Note: this circuit is only suitable for tone signals; it would be no good for speech or music). Current dr~in is around 300µA which can be easily supplied by a 9V battery (Eveready type 216 or equivalent). 15k .------------.--------------u+9V PARTS LIST 10!1 1 PC board, code SC06106911 , 50 x 48mm 1741 opamp(IC1) 1 100Q trimpot (VR1) 100 25VW!_ 0.1 o--jl--WA-+--11....__-=-t AUDIO INPUT 220 .0471 t6V)W r o, SPEAKER 10ll .,. Capacitors 1 10µF 16VW electrolytic 2 0.1 µF metallised polyester or ceramic 1 .001 µF metallised polyester or ceramic Fig.2: a simple audio amplifier based on an LM386 IC can be added to the active filter if you don't wish to use headphones. Resistors (0.25W, 5%) 1 82kQ 1 2.7kQ 1 15kQ 1 47Q VRl is used to adjust the centre frequency of the filter, which should be tuned to the offset frequency of the receiver. Most CW operators seem to use 700-B00Hz. There is sufficient range in this control to vary the centre frequency from 600Hz to 1.ZkHz. This is even useful when copying SSB signals , as the filter is capable of rejecting adjacent channel heterodynes, whistles and noise. The circuit values for our filter were determined by solving the three simple equations below: Miscellaneous Battery, zippy box, hookup wire, solder, etc. = R3 X 7t X fc X C = 84.9kQ (2) Gain A = R3/ZR 1 ; therefore R1 = R3/ZA = 2.83kQ (1) Q (3) VRl = Q/(ZQ2-A)27t x fc x C = 54Q where C2 = C3 = C = 0.1 x 10- 6 and fc = 750Hz As can be seen, we selected 0. lµF as the value for CZ and C3, merely because it is a convenient value. This enables us to calculate R3, as we already know the target centre frequency and Q. Simple multiplication and division allows us to calculate the Rl and VRl values. We used 0. lµF as the input coupling capacitor, and .00luF as the output capacitor, which ensures a good match to a pair of high impedance headphones, or external audio amplifier. Of course, the unit could be expanded to include a simple audio amplifier as shown in the circuit of Fig.2. This configuration would require an external power supply connection to run the audio amplifier, anq obviously a larger enclosure to house the sp eaker. The values for Rl, RZ, and R3 have been rounded off to the closest preferred value resistors but, to be precise, two discrete values could be used to make up the exact value calculated, if you wish. Provision has been made on the PC board to use two resistors in each position. RZ is selected as having a value of twice the Q, to ensure minimum offset. Building it The PC board measures just 50 x 48mm (code SC06106911) and is small enough to be built into either a plastic zippy box or inside the actual receiver with which it is to be used. An easy way to mount the PC board is with a piece of double-sided tape, either inside the plastic box or the receiver itself. Fig.3 shows the parts layout on the PC board. You can install the parts in any order you wish but take care with the polarity of the IC and the lOµF electrolytic capacitor. Alignment of the filter is simple. You just connect the audio output of the receiver to the filter and, while listening to a CW or SSB signal, carefully adjust VRl for the clearest sigcontinued on page 93 The book of facts! FERROMAGNEIIC CORF.s • Materials • Design • Applications ill Amidon I Ie-[Due ~ __.:- o., AUDIO J INPUT_....--. & I .__.,.-- ~Ou .E o1 _!- HEADPHONES ....---- n 0,~ Mo, GDe ~·~ ~t;J \ -r GND +9V OUTPUTTO Fig.3: here's how to install the parts on the PC board. Note that Rl, R2 & R3 have been rounded off to the nearest preferred values but you can use two discrete resistors to make up the exact value of each if you wish. The second resistor simply replaces a wire link in each case. Complete data on over 500 types of Iron Powder and Ferrite cores and assemblies, all available in Australia!$,~ paid from: 5•n U. Upost STEWART ELECTRONIC COMPONENTS Pty. Ltd. ACN 004 518 898 P.O. Box 281 Huntingdale 3166 PH (03)543-3733 FAX (03)543-7238 ]UNE 1991 89 Silicon Chip BACK COPIES 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. July 1988: Stereo Control Preamplifier, Pt.2; Fitting A Fuel Cut-Off Solenoid ; Booster For TV & FM Signals; The Discolight Light Show, Pt.1; Tone Burst Source For Amplifier Headroom Testing; What Is Negative Feedback, Pt.3; Amcron MA1200 Power Amplifier Review ; Amplifier Headroom - Is It A Con? August 1988: Building A Plasma Display; Universal Power Supply Board; Remote Chime/Doorbell ; High Performance AC Millivoltmeter, Pt.1 ; Discolight Light Show, Pt.2; Getting The Most Out Of Nicad Batteries; Data On Insulated Tab Triacs. September 1988: Hands-Free Speakerphone ; Electronic Fish Bite Detector; High Performance AC Millivoltmeter, Pt.2; Vader Voice; Motorola MC34018 Speakerphone IC Data; National Semiconductor LM12 150W Op Amp Data & Applica- tions; What Is Negative Feedback, Pt.4. October 1988: Stereo FM Transmitter (Uses Rohm BA1404); High Performance FM Antenna; Matchbox Crystal Set; Electronic House Number; Converting A CB Radio To The 28MHz Band ; Queensland's Powerful Electric Locomotives. November 1988: 120W PA Amplifier Module (Uses Mosfets); Poor Man's Plasma Display; Automotive Night Safety Light; Adding A Headset To The Speakerphone; How To Quieten The Fan In Your Computer; Screws & Screwdrivers, What You Need To Know ; Diesel Electric Locomotives. December 1988: 120W PA Amplifier (With Balanced Inputs), Pt.1 ; Diesel Sound Generator; Car Antenna/ Demister Adaptor; SSB Adaptor For Shortwave Receivers; Electronics & Holden's New V6 Engine; Why Diesel Electrics Killed Off Steam; Index to Volume 1. January 1989: Line Filter For Computers; Ultrasonic Proximity Detector For Cars ; Simple Computer Sound Repeater; 120W PA Amplifier (With Balanced Inputs) Pt.1; How To Service Car Cas- sette Players; Massive Diesel Electrics In The USA; Marantz LOSO Loudspeakers. February 1989: Transistor Beta Tester; Minstrel 2-30 Loudspeaker System ; LED Flasher For Model Railways (uses LM3909); Build A Simple VHF FM Monitor (uses MC3362) , Pt.1; Lightning & Electronic Appliances; Using Comparators to Detect & Measure. March 1989: LED Message Board, Pt.1 ; 32-Band Graphic Equaliser, Pt. 1; Stereo Compressor For CD Players; Map Reader For Trip Calcu lations; Amateur VHF FM Monitor, Pt.2 ; Signetics NE572 Compandor IC Data; Electronics For Everyone Resistors. April 1989: Au xiliary Brake Light Flasher; Electronics For Everyone: What You Need to Know About Capacitors; Telephone Bell Monitor/ Transmitter; 32-Band Graphic Equ aliser, Pt.2; LED Message Board, Pt.2. l -__ _ ------------------------------- --- Use this handy form to order your back copies Please send me a back issue for: 0 September 1988 0 October 1988 0 February 1989 0 March 1989 D July 1989 D August 1989 0 December 1989 0 January 1990 0 May 1990 0 June 1990 o October 1990 O November 1990 O March 1991 D April 1991 0 O 0 D O 0 May 1988 November 1988 April 1989 September 1989 February 1990 July 1990 D December 1990 0 May 1991 Enclosed is my cheque/money order for $_ __ 0 O 0 O 0 0 0 July 1988 December 1988 May 1989 October 1989 March 1990 August 1990 January 1991 or please debit my: August 1988 January 1989 June 1989 November 1989 April 1990 September 1990 February 1991 0 Visa Card O Master Card $5.00 each (includes p&p). Overseas orders add $1 each for postage. NZ orders are sent air mail. Card No. Signature _ __ _ __ _ _ _ _ _ _ _ Card expiry date_ _ O Bankcard 0 0 0 O 0 O 0 /_ _ Name _ _ __ _ _ _ _ _ __ _ _ _ _ _ _ _ _ _ _ __ __ Street _ _ _ _ __ _ _ __ _ _ _ _ _ _ _ _ _ _ _ _ _ __ Suburb/town _ _ _ _ __ _ _ __ _ _ _ _ Postcode _ __ __ _ Detach and mail to: SILICON CHIP PUBLICATIONS PO BOX 139 COLLAROV BEACH NSW 2097 Or call (02) 979 5644 & quote your credit card details. Fax (02) 979 6503 x I I -- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -90 . SILICON CHIP ers Compared) ; What To Do When Your Computer Goes Bung, Pt.4. September 1990: Music On Hold For Your Telephone; Rem·ote Control Extender For VCRs; Power Supply For Burglar Alarms; Low-Cost 3Digit Counter Module; Voice Mail For Your Computer; Simple Shortwave Converter For The 2Metre Band; How To Make Dynamark Labels. October 1990: Low-Cost Siren For Burglar Alarms; Dimming Controls For The Discolight; Surfsound Simulator; DC Offset For DMMs; The Dangers of Polychlorinated Biphenyls; The Bose Lifestyle Music System; Using The NE602 In Home-Brew Converter Circuits. May 1989: Electronic Pools/Lotto Selector; Synthesised Tom-Tom; Biofeedback Monitor For Your PC; Simple Stub Filter For Suppressing TV Interference; LED Message Board, Pt.3; Electronics For Everyone - All About Electrolytic Capacitors. ,!une 1989: Touch -Lamp Dimmer (uses Siemens SLB0586); Passive Loop Antenna For AM Radios; Universal Temperature Controller; Understanding CRO Probes; LED Message Board, Pt.3; Coherent CW - A New Low Power Transmission Technique. July 1989: Exhaust Gas Monitor (Uses TGS812 Gas Sensor) ; Extension For The Touch-Lamp Dimmer; Experimental Mains Hum Sniffers; Compact Ultrasonic Car Alarm; NSW 86 Class Electric Locomotives ; Facts On The PhaxSwitch - Sharing Your Phone Line With A Fax Machine. August 1989: Build A Baby Tower AT Computer; Studio Series 20-Band Stereo Equaliser, Pt.1; Garbage Reminder - A 7-day Programmable Timer; Introduction To Stepper Motors; GaAsFet Preamplifier For The 2-Metre Band; Modern 3Phase Electric Locomotives. September 1989: 2-Chip Portable AM Stereo Radio (Uses MC13024 and TX7376P) Pt.1; AlarmTriggered Telephone Dialler; High Or Low Fluid Level Detector (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 BA1404 & TOA 7000) Pt.1 ; GaAsFet Preamplifier For Amateur TV ; 1Mb Printer Buffer; 2-Chip Portable AM Stereo Radio , Pt.2; Installing A Hard Disc In The PC; A Look At Australian Monorails. November 1989: Radfax Decoder For Your PC (Displays Fax, RTTY and Morse); Super Sensitive FM 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 Pi lbara Iron Ore Railways . 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- December 1989). January 1990: Service Tips For Your VCR; Speeding Up Your PC; Phone Patch For Radio Amateurs ; High Quality Sine/Square Oscillator; Active Antenna Kit; The Latest On High Definition TV; Speed Controller For Ceiling Fans; Designing UHF Transmitter Stages. February 1990: 16-Channel Mixing Desk; High Quality Audio Oscillator, Pt.2; The Incredible Hot Canaries; Random Wire Antenna Tuner For 6 Metres; Phone Patch For Radio Amateurs, Pt.2; PC Program Calculates Great Circle Bearings;A Look At Computer Interfacing. March 1990: 6/12V Charger For Sealed LeadAcid Batteries; Delay Unit For Automatic Antennas; Workout Timer For Aerobics Classes; 16Channel Mixing Desk, Pt.2; Using The UC3906 SLA Battery Charger IC; Digital Waveform Generation Using a PC; The Controls On A Model Aircraft. April 1990: Dual Tracking ±50V Power Supply; VOX With Delayed Audio ; Relative Field Strength Meter; 16-Channel Mixing Desk, Pt.3; Simple Service Tips For Your Microwave Oven; 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; The Mozzie CW Transceiver; Waveform Generation Using A PC, Pt.3; 16-Channel Mixing Desk, Pt.4; What To Do When Your Computer Goes Bung , Pt.1; Electronic Load For Checking Power Supplies. 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; What To Do When Your Computer Goes Bung, Pt.2. July 1990: Digital Sine/Square Generator, Pt.1 (Covers 0-S00kHz); Burglar Alarm Keypad & Combination Lock; Simple Electronic Die ; Low-Cost Dual Power Supply; Inside A Coal Burning Power Station; What To Do When Your Computer Goes Bung, Pt.3; Digital Waveform Generation Using A Computer, Pt.4; Weather Fax Frequencies. August 1990: High Stability UHF Remote Transmitter; Universal Safety Timer For Mains Appliances (9 Minutes) ; Horace The Electronic Cricket; Digital Sine/Square Wave Generator, Pt.2; The Tube Vs. The Microchip (Two Shortwave Receiv- November 1990: Low-Cost Model Train Controller; Battery Powered Laser Pointer; A Really Snazzy Egg Timer; 1.5V To 9V DC Converter; How To Connect Two TV Sets To One VCR; Introduction To Digital El ectronics; Simple 6Metre Amateur Transmitter. December 1990: DC-DC Converter For Car Amplifiers; The Big Escape - A Game Of Skill; Wiper Pulser For Rear Windows; Versatile 4-Digit Combination Lock; 5W Power Amplifier For The 6Metre Amateur Transmitter; The Green CD Pen Controversy. January 1991: Fast Charger For Nicad Batteries, Pt.1; Have Fun With The Fruit Machine; TwoTone Alarm Module; Laser Power Supply (For Tubes With Ratings Up To 10mW); LCD Readout For The Capacitance Meter; How Quartz Crystals Work; The Dangers When Servicing Microwave Ovens; Electric Vehicles - The State Of The Art. February 1991: Synthesised Stereo AM Tuner, Pt.1 ; Three Inverters For Fluorescent Lights; LowCost Sinewave Oscillator; Fast Charger For Nicad Batteries, Pt.2; How To Design Amplifier Output Stages; Tasmania's Hydroelectric Power System. March 1991: Remote Controller For Garage Doors, Pt.1; Transistor Beta Tester Mk.2; Synthesised AM Stereo Tuner, Pt.2; Multi-Purpose 1/0 Board For PC-Compatibles; Universal Wideband RF Preamplifier For Amateurs & TV ; A Look At Config.Sys & Ansi.Sys; High-Voltage DC Transmission Systems. April 1991: Steam Sound Simulator For Model Railroads; Simple 12/ 24V Light Chaser ; Remote Controller For Garage Doors, Pt.2; Synthesised AM Stereo Tuner, Pt.3; A Practical Approach To Amplifier Design, Pt.2; The Easytune FSK Indicator For HF Transmissions; Playing With the Ansi.Sys File. May 1991: Build A DTMF Decoder; 13.SV 25A Power Supply For Transceivers; Stereo Audio Expander; Fluorescent Light Simulator For Model Railways; How To Install Multiple TV Outlets, Pt.1; Motors For Electric Vehicles; High-Power DC Transmission- Lines. PLEASE NOTE: All issues from November 1987 to April 1988, plus June 1988, are now sold out. All subsequent issues are presently in stock. For readers wanting articles from issues out of print, we can supply photostat copies (or tearsheets) at $5.00 per article, including postage. When supplying photostat articles or back copies , we automatically supply any relevant Notes & Errata, at no extra charge. JUN E 1991 91 ASK SILICON CHIP Got a technical problem? Can't understand a piece of jargon or some technical principle? Drop us a line and we'll answer your question. Write to: Ask Silicon Chip, PO Box 139, Collaroy Beach, NSW 2097. How secure is the Garage Door Opener? The Garage Door Opener in the March issue looks like a very useful circuit but I wonder how secure it is. For example, the transmitter and receiver have 312 possible unique codes that can be used (531,441). Couldn't someone wanting to break in adulterate a transmitter by hooking the encoding chip up to a Tristate counter so that it transmits all 531,441 codes in sequence, each in a short burst? I'm only guessing how long it would take to transmit each code. If the time taken to transmit each code was, say, 10 milliseconds or less, then perhaps breaking in this way could be possible. Is this actually a problem or is there something in the circuit that would prevent this happening? Ifnot, would it be possible to make the circuit "lockout" any further data for a period if any incorrect codes were received? Another way someone could break in would be to build the receiver por- Flashing lights for technical frippery I know you like to create electronic projects of excellence, which equal or outperform their commercial equivalents, but could I suggest a project which is universally deemed to be the most useless, frivolous waste of electronic components one could imagine for a hifi system? That project, of course, is a spectrum analyser; ie, that component which displays the power strength of each band of a channel (using at least 100 LEDs per channel - 10 bands of 10 LEDs each). The reason I ask is because some people like myself want to' "flash up" their hifi system with something more than the occasional power LED, and to be able to see 92 SILICO N CHIP tion of the circuit and make a tape recording of the output. They could then wait until the garage owner left and make a recording of the detected UHF transmitter signal as the owner closed the door. They could re-transmit this recording through the Hartley oscillator of the transmitter and the door would open. Why not? (R. J., Toowoomba, Qld). • It is true that someone who wanted to break in could have a computer program or other circuit which transmitted all possible codes. Supposedly, that is how some car thieves manage to overcome UHF remote control burglar alarms although we believe that these alarms have far less code combinations. If this was perceived to be a problem, an additional circuit which senses that wrong combinations are being tried could be used to lock the system up. In reality, though, we think that someone who was that keen to break into a house would take a much quicker route and break a window or the hifi actually doing something! Please give it some thought, as I can't imagine it would be too difficult or terribly expensive. (DSE sells bags ofl00 LEDs for 30 bucks). I remain your most avid reader. (M. B. South Yarra, Vic). • It is true that you would need around 100 LEDs per channel and the driving circuitry itself would not be particularly expensive. However, the full circuit of a stereo audio spectrum analyser is quite complex and would be very expensive to publish. In fact, we did hav·e a look at this project idea quite some time ago and concluded that it would not be viable. However, we will have another look at the suggestion and see if it can be done in a simpler way. door. And don't forget, gaining entry via a garage door would not get you past a house burglar alarm, if one was installed. Cure for amplifier thump at switch off I was interested to read a letter in the "Ask Silicon Chip" pages of the April issue about amplifier thump at switch off. Some time ago, I built a 100 watt amplifier with power supply. And for a long time (years), the beast thumped at switch off. Then one day I found that making the transient suppression capacitor across the mains switch bigger (was .033µFwent to about .047µF or .068µF) cured the problem completely. (R. P., Belgrave Heights, Vic). • As far as your amplifier is concerned, increasing the suppression capacitor may solve the turn off thump but it may also leave the amplifier partly energised permanently. You can check this by checking the supply rails of the amplifier when it is supposed to be off. We're betting that it will have quite a high supply voltage, maybe as much as ±10V, which means that the amplifier hasn't thumped because it ain't really off! PAL systems are incompatible One of my friends brought a National NV777 VCR from South Africa. Due to the Australian system, he is unable to use that here. I would like to know whether you can give me any constructive ideas to convert to Australian standards. (K. P., West Ryde, NSW). • Unfortunately, the Australian and South African systems are not really compatible, even though they are both based on PAL. Your best chance is to contact a local serviceman or National Panasonic Australia Pty Ltd direct at 95 Epping Road, North Ryde (phone 887 5454) and see if they can re-align the VCR to suit Australian standards. Moveable targets for a pistol range I wish to set up a pistol range. What is required is a set-up of five turning targets. There are systems on the market which have a target of about 600 sq cm for shooting from 25 metres. What I need is a system using a target of about 150 sq cm to allow me to shoot from 10 metres with an air pistol. The system needs to allow all five targets to turn together and be controlled from 10 metres away. Targets should turn in 0.2 seconds and need to be faced at the shooter for variable times, to suit rapid Notes & Errata Garage Door Controller, March & April 1991: two lOµF capacitors associated with IC7 need to be changed to lµF to make sure the controller always comes on in the Down mode when power is reconnected. They are the capacitors connected to pins 3 and pin 5 of IC7. The designer has advised us that the timing resistor between pins 15 and 16 ofICl in the transmitter should now be lMQ while the equivalent resistor between pins 15 and 16 ofIC2 in the receiver should be 1.2MQ. The higher resulting transmitter code frequency allows for the inevitable drop in battery voltage. IC2 can cope with the different code frequency. A 4.7kQ supply decoupling resis- fire, standard gun and centre fire shooting. Do you have any suggestions and some idea of costs? (J. S., Casuarina, NT). • The project you propose is a little beyond what we would normally publish in the magazine. The timing and control circuit could be fairly simple though and you could probably use standard servodrives, as used in radio controlled cars and planes, for turning the targets. These are relatively cheap and can be used in conjunction with a radio controller which would suit your purpose for remote control. tor was not shown on the UHF receiver circuit but was included on the PC overlay diagram although it is shown unlabelled. A 4 70kQ resistor from pin 11 of IC la to OV was omitted from both the circuit and PC overlay diagram. It will need to be soldered onto the copper side of the board. A small section of PC track is missing from the pattern near TPl. It joins the 4.7MQ resistor and 15pF capacitor together. Only one of the two diodes associated with the paralleled relays RLAl and RLA2 is needed; the other one can be omitted. The same applies for the diodes associated with relays RLA3 and RLA4. Also, for best operation, roller doors should have a 2kg to 3kg weight added adjacent to their bottom edge. SENDINYOUR APPLICATION For your share of the prizes In the March and April issues of Silicon Chip we published the RemoteControllerfor Garage Doors. The feedback from this project has been enormous. You have to send in your application of how else this kit canbeused.Plusacoupleofphotos if you actually put the application into practice. In conjunction with Oatley Electronics this is your opportunity to share your application and possibly pick up a prize as well. Even if you have not built the Garage Remote you can still send in an entry. Entries close on the 30th ofAugust 1991, and will be judged by the technical staff at Silicon Chip. What you could win? 1st Prize. 7mW HE-NE Laser and Inverter. All you need to power · this unit is 12-14VDC. This is a red Laser and is valued at: $580.00 2nd Prize. Infra Red Night Viewer.See in the dark with this great night viewer. In this kit you will get a NEW 6032 Image converter tube, Case and the components kit. This prize is valued at: $339.00 Amateur Radio - continued from page 89 nal. In the case of a CW signal, as the centre frequency of the filter is adjusted to match the receiver offset frequency (700-800Hz), the level of recovered audio will dramatically increase as the audio signal enters the bandpass of the filter. This will make signals far easier to copy, even in the presence of strong adjacent signals or noise. References Active Filter Cookbook, by Don Lancaster. Published 1975 by Howard W. Sams & Co. Inc; The ARRL Handbook; Ham Radio Magazine, January 1990. 3rdPrize. lmWLaser head with a commercial inverter. All you need is a 12V supply. This prize is valued at: $309.00 SC06106911 I Fig.4: here is the full-size pattern for the PC board. Alternatively, the circuit could be built on Veroboard. Plus 10 Ultrasonic movement alarm kits valued at $50.00 ea. · SEND ENTRIES TO: GARAGE DOOR COMPETITION P.O. BOX 139 COLLAROY BEACH NSW 2097 JUN E 1991 93 ORDER FORM USE THIS FORM FOR ALL YOUR SILICON CHIP PURCHASES SILICON CHIP BINDERS: Yes! Please rush me_ _ _ SILICON CHIP binder(s)<at> $A14.95 each including postage. (Overseas orders please addA$3.00 each for postage). Total $A_ _ _ __ SPORTS SHIRT: Please send me _ __ Sport Shirt(s)<at> $A24.95 including postage. (Overseas orders please add $A3.00 for the additional postage). Size(s): S(Qty)_ M(Qty)_ L(Qty)_ XL(Qty)_ XXL(Qty)_. Total $A_ __ SLOPPY JOE: Please send me _ _ Sloppy Joe(s)<at> $A27.95 including postage. (Overseas orders please add A$3.00 for the additional postage). Size(s): S(Qty)_M(Qty)_L(Qty)_XL(Qty)_XXL(Qty)_ . Total A$_ __ BACK ISSUES: $A5.00 each (including postage). Overseas orders add $Al.00 per issue for postage. YEAR ISSUE YEAR YEAR ISSUE ISSUE ISSUE YEAR TOTAL $A . SUBSCRIPTIONS . RATES: □ NEW SUBSCRIPTION: Month to Start □ RENE WAL: Sub No. (PLEASE TICK ONE) Start In 2 years (24 issues) 1 year (12 issues) O$A84 O$A42 □ GIFT SUBSCRIPTION: Month To Start Your Details Australia Australia with Binder(s) O$A105 O$A53 Mr/Mrs/M s: NZ & PNG (Airmail) O$A130 O$A65 Overseas Surface Mail O$A130 O$A62 Overseas Airmail O$A240 O$A120 Address Postcode Daytime telephone number: _ _ _ _ _ _ __ Enclosed is my cheque/money order for $_ _ _ or debit my □ I EBI □ 1 11m1 □ 1 VISA I 11 111 1111111111~11~~ Card expiry date Signature _ _ _ _ _ _ _ _ __ ~--~. (02) .979 6503 Fax the coupon with your Credit Card details 24 Hours, 7 Days a Week _ _!_ _ "fi'"'- Gift Subscription Details Message: _ _ _ _ _ _ _ _ _ _ _ _ _ __ Mr/Mrs/Ms: _ _ _ _ _ _ __ _ __ _ __ Address: _ _ _ _ _ _ _ _ _ __ _ _ __ _ _ _ _ _ _ _ _ _ _ _Postcode_ _ __ (02) 979 5644 9am - 5pm Mon-Fri. Please have your Credit Card details ready. Mail coupon to: FREEPOST 25 Silicon Chip Publications PO Box 139 Collaroy Beach NSW 2097 No stamp required in Australia MARKET CENTRE Cash in your surplus gear. Advertise it here in Silicon Chip . r----------------- - -------7 CLASSIFIED ADVERTISING RATES FOR SALE WEATHER FAX programs for IBM XT/ ATs *** "RADFAX2" is a high resolution, shortwave weather fax, Morse & RTTY receiving program. Needs CGA, SSB HF radio & Radfax decoder. Also "RF2HERC", "RF2EGA" & "RF2VGA", same as RADFAX2 but suitable for Hercules, EGA & VG A cards respectively. $35. *** "SATFAX" is a NOAA, Meteor & GMS weather satellite picture receiving program. Uses EGA & VGA modes, needs EGA or VGA colour monitor & card, plus "WEATHER FAX" PC card. $45. *** All programs are on 5.25-inch or 3.5-inch discs (state which) & include documentation . Add $3 postage. ONLY from M. Delahunty, 42 Villiers St, New Farm, 4004 Old. Phone(07)3582785. Advertising rates for this page: Classified ads - $7.00 for up to 15 words plus 40 cents for each additional word. Display ads (casual rate) - $20 per column centimetre (Max. 10cm). Closing date: five weeks prior to month of sale. If you use a PO Box number, you must include your permanent address and phone number for our files. We cannot accept ads submitted without this information. To run your classified ad, print clearly on the lines below or on a separate sheet of paper & send the form together with your cheque or credit card details to : Silicon Chip Classifieds, PO Box 139, Collaroy Beach, NSW 2097. Or fax the details to (02) 979 6503. LAB LASERS . 0.5mW to 2mW HeNe lasers complete. Ideal for students or hobbyists. Australian made. $440- $640. Phone M.C.E. Lasers (03) 357 0055. CIRCUIT DESIGN SOFTWARE. Design your own .008% THD Sinewave Generator from 90Hz-30kHz using the PCB in SILICON CHIP, February 1991 . $20 inc. p&p. Design & build you own Audio Power Amplifier up to 20W. On-screen circuit diagram and hardcopy facilities. Instructions included. $30 inc. p&p. Custom-make your own SLA Battery Charger using the UC3906 IC (4-30V). Designed by the author of the SILICON CHIP March 1990 project. $20 inc. p&p. Enclosed is my cheque/money order for $_ _ _ _ or please debit my O Bankcard o Visa Card 0 Master Card Card No. Signature_ _ _ _ _ _ _ _ _ _ _ Card expiry date_____ _ Name _ _ __ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __ Street _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __ Suburb/town _ _ _ _ __ _ _ __ _ _ Postcode_ _ _ _ __ XI I I I I I I I I I DIGITAL WAVEFORMS FROM A PC As described in SILI CON CHIP in March, May & June 1990. The software can also be used for the similar project (Simple PC Function Generator) described in Electronics Australia in January 1989. Software & PC Board: $39.95 incl. p&p. Software only: $32.50 incl. p&p. Money order or cheque. M. Radvanyi, PO Box 49, Kingswood , NSW 2749. L-------------------------~ JUN E 199 1 95 r ..... MEMORV·EXPANSION Advertising Index Prices at May 10th 1991 DRAM DIP ZIP SIMM & SIP SPEED lns) TYPE 120 2.20 1.80 100 2.35 2.00 2.50 6.10 80 70 4164 2.20 2.40 41256 2.75 41464 411000 7.30 7.90 38.00 1MBx4 (Static) 256K x 9 20.50 21.00 22.50 62.00 72.00 81.00 1MBx9 295.00 4MB X 9 SimmSockets30 X 1Vertical 1.70 Simm Sockets 30 x 2 Angle 3.50 Simm Sockets 30 x 2 Vertical 3.20 ~PELHAM CO-PROCESSORS INTEL CYRIX 8087 8087-1 8087-2 80287-8 80287-10 287XLT 287XL 387DX20 387DX25 387DX33 387SX16 387SX20 120.00 175.00 175.00 272.00 275.00 285.00 285.00 550.00 693.00 848.00 432.00 510.00 ETS, PO BOX 491, NOARLUNGA CENTRE, SA 5168. Phone: (08) 382 8919 Antique Radio Restorations ....... 96 IIT Arista ............................... 33,61,73 Back Issues .......................... 90,91 178.00 David Reid Electronics ........ . IFC,1 Dick Smith Electronics .. .. ...... 11-13 510.00 640.00 780.00 406.00 440.00 480.00 600.00 670.00 395.00 Electronic Solutions ................ .. . 31 Electronic Toy Services ............. 96 Electronics World ....................... 85 Sales Tax 20%. Overnight Delivery. Credit Cards Welcome 1st Floor, 100 Yarrara Road , Pennant Hills, N.S.W. 2120 Tel(02)980-6988 MODEL TRAIN CONTROLLER project, SILICON CHIP, November 1990, $19.95 plus $2.50 p&p. Plugpack, 12VAC, 1.7A, suitable for the above (use rectifier) , $29.95 plus $4.00 p&p. Kits built & repaired. Prototype production board supplier to the hobbyist & supplier of SILICON CHIP project PCBs. Altronics ...................... .......... 22-23 Fax(02)980-6991 ~ FIX-A-KIT $20.00 PER HOUR LABOUR 3 MONTHS WARRANTY ON REPAIRS 12 MONTHS WARRANTY ON CONSTRUCTION Service to most types of electronic equipment TECHNICAL ASSISTANCE HYCAL ELECTRONICS Design, Manufacture & Repair of Electronic Equipment Trading Hours 8am to 3pm, Monday to Friday (02) 633 54 77 Elmeasco ................. .... .......... OBC Geoff Wood Electronics .. ... ........ 87 Harbuch Electronics .. ................ 56 Hycal Instruments ............. .... ..... 96 Jaycar Electronics ................ 45-52 J.V. Tuners ................. .... ... ... ... ... 57 Kalextronics .... .. .. .. ... .... ........ ...... 61 M. Radvanyi .............................. 95 Oatley Electronics ............ . 5,33,93 PC Computers .. ...... .. .. .. ............. 96 PC Marketplace .... ..... .. ..... .. ....... 75 Pelham ............................... ... .... 96 Raytec Data Systems ...... ... ....... 56 MAX 1/0 Board Kit $149.00. Built & Tested $269.00. • 7 x Relays SPST 2 amps each • 8 x Switch inputs (TTL) • 1 x DAG (Digital to Analog converter) • 1 x ADC ( Analog to Digital converter) • 4 x Motor Drive outputs (40mA ea.) • 1 x Programmable timer output. MAX includes a 20-page manual with all schematics, parts layout etc., a 360K PC-compatible floppy with diagnostic and sample software in GW-Basic. MAX runs from a PC compatible printer port for full compatibility with a large range of computers. Same day dispatch of orders. Credit cards or personal cheques welcome. Phone (08) 332 6513 or Fax (08) 364 0902 (24 hours) PC Computers, 36 Regent St, Kensington, SA., Buy all three for $50 and save $20! IBM/XT/AT compatible, 5 .25-inch 360K disc only, CGA/EGA/VGA, MS-DOS 3.2 or later. Send cheque/ money order to: D . Yates, PO Box 134, French's Forest, NSW 2086. WHOOPS! MY Z-80 BASED PBUFF printer buffer just doubled its memory capacity again. Over 3000 kits now sold. Combinations of DIP/SIPP/SIMM DRAMS in 9 memory sizes up to 2Mb. Rev J board, Ver 4.3 EPROM & instructions $39. Cable board $9. P&P $3. Serial board & many other options available. Send a 43c stamp for a free catalog to: 96 SILICON CHIP TRANSFORMER REWINDS ALL TYPES OF TRANSFORMER REWINDS TRANSFORMER REWINDS Reply Paid. No.2, PO Box 438, Singleton, NSW 2330. Ph: (065) 761291. Fax: (065) 761003. RCS Radio ........ .... ........ ........ .. .. 86 Resurrection Radio .................... 81 Rod Irving Electronics .......... 34 ,35 62,63,82,83 Sheridan Electronics .......... .. ..... 77 Don McKenzie, 29 Ellesmere Crescent, Tullamarine 3043. ANTIQUE RADIO Silicon Chip Binders .............. .. IBC Stewart Electronics ............. .. ..... 89 Subscriptions ........................... .. 94 Transformer Rewinds .. .... .......... 96 ANTIQUE RADIO restorations. Your one-stop radio repair shop. Specialising in restoring vintage radios including chassis rewiring, re-condensing, quality new parts, valves, valve sockets, speakers, power & audio transformers. Secondhand radio dials & parts for most brands & models. About 400 radios in stock for sale, restoration & parts. Every restored wireless is covered by a 2year warranty on parts & labour. We restore damaged woodwork & cabinets & French polish (approx. 40coats). Vintage car radios available for sale or restoration. Repairs done on tape decks & amplifiers. Open Sat. 1 Oam-5pm; Sun. 12.30-5pm. 109 Cann St, Bass Hill, NSW 2197. Phone (02) 645 3173 BH or (02) 726 1613 AH. SC PC Boards Printed circuit boards for SILICON CHIP projects are made by: • Electronic Toy Services, 2/ 111 Glynville Drive, Hackham West, SA 5163. Phone (08) 382 8919. • Jemal Products , 5 Forge St , Welshpool, WA 6106. Phone (09) 350 5555. • Marday Services, PO Box 19-189, Avondale, Auckland, NZ. Phone 88 5730. • RCS Radio Pty Ltd, 651 Forest Rd, Bexley, NSW 2207. Phone (02) 587 3491. * High quality * Holds up to 14 issues • * 80mtQ. internal width * Gold printed with SILICON logo on spine and front cover QHIP These beautifully made binders will protect y,ou.r copies of SILICON CHIP. We are especially })leased with their look and quality. As soon as the first batch came in, everybody on our staff wanted them to store their own personal issues. You·will too. How To Phone (02) 979 5644 Fax (02) 979 6503 ORDER: Made with a distinctive two tone green high-quality vinyl specially selected for SThIOON CMIP, and with heavy board covers, each binder holds a year's issues (the 14 issues of Vol.l or the 12 issues of N'ol.2). They will look really sma:ut on your bookshelf. To order your binders, fill in the coupon on page 94 and send it to SILICON CHIP, PO Box 139, Collaroy !Beach, 'NSW 2097. Alternatively phone (02) 979 5644 and quote your eredit card details, or fax your orders to (02) 979 6503. Price $Al 1.95 plus $A3 each for postage and pack'.ing. (NZ postage and packing $A6.)