0 ©® >r november 1980 - UK 03 selektor an r.p.m. indicator as an economy guide A car engine is most efficient when the amount of energy it produces is closest to the amount consumed. This occurs at an engine speed that produces the maximum torque output. This circuit features both optical and acoustic indications to enable the driver to change gear at the opti- mum time in order to keep the engine speed within its most efficient range. draught detector However well insulated you think your house is, there are bound to be a few nooks and crannies which will allow interior heat to escape. With the aid of this electronic draught detector they will be found quite easily and the results may surprise you. how to recycle dry cell batteries energy saving know how The 'energy crisis' sounds as familiar to our ears as VAT - its something we have to cope with every day of our lives. It makes sense to save energy but a clear indication as to how and where it could be saved in the home is rarely given. This article takes a look at the central heating system, one of the largest domestic energy consumers. simple fuel economy meter A meter indicating fuel consumption on a digital display while the car is moving would appear to be a popular project. With the aid of the modules described in this article it should be possible to use any transducer. \Z contents UK EDITORIAL STAFF T. Day E. Rogans automatic pump control 11-25 In most central heating systems the pump has to work continually both day and night. Considering that a small pump can use up to 100 watts, it can be seen that the automatic control featured in this article is a good investment. long life technique in light bulbs 11-28 The standard household light bulbs currently on the market are designed to last about 1000 hours. Where bulb failure can lead to security risks or high maintenance costs, it would be an advantage if their life could be extended. How this can be done without cutting down on light level too much can be discovered in this article. automatic curtain control 1 1-30 fridge alarm 11-34 Modern fridges contain thick layers of insulation to keep the cold in and the heat out. Even so, if the door is left open for longer than necessary no amount of insulation will keep costs down. With this circuit the fridge will complain loudly on its own accord if the door remains open for too know the ins and outs of your central heating system 11-36 Most people may consider that their system is working perfectly but in practice things have been found to turn out quite differently. missing links 11-38 energy saving motor control 11-39 Improved motor control circuits can cut down consumption down by 50% as this article shows. coffee machine switch 11-42 With the aid of the circuit presented in this article your coffee maker can save energy by switching off its hot plate when the coffee pot is picked up. It then gives a warning signal so that if the remaining coffee is to be kept warm a button must be pressed. operational hours counter 11-44 market 11 -47 advertising index UK-24 elektor november 1980 - UK 11 BATTERY LIFE AUTO BATT’ WARNING Introducing the latest professional state-of-the-art 3 '/ 2 -digit DMM - at really old- fashioned prices! From just an unbelievable £39.95 inc. VAT, plus £1.15 p&p! If you want an Autoranging For only We’ve got to hand it to you! * ZERO ADJUSTMENT * FULL AUTORANGING * 3 '/2-DIGIT LCD WITH * AUTO UNIT DISPLAY 200 HRS CONTINUOUS « CONTINUITY TEST (61 10 and 6100 only) 10 AMP AC/DC (6110 and 6220 only) Why such a low, low price? Because the A/D converter and display are custom built! This is a genuine top-spec DMM. Check these features for unbeatable value - you won't find a hand-held DMM with these features at these prices again! Build the Practical Electronics handheld DMM.This superb product ^B ^ offers professional precision with ^B \ extended battery life. Five function ^B \ operation (AC and DC VOLTS. AC ■ t, and DC CURRENT. RESISTANCE) ■ B with ability to check diodes. 0.5" LCD ^B a W display with 'Battery Low' warning. ^B 1 \ Auto-polarity, Auto-zero. Full protection ^B \ \ against transients and overloads with ^B \ \ ability to withstand mains on any range. ^B \ 0.5% basic DC accuracy and 1 5 different ranges. It measures AC/DC ^B , ™ voltages from 0.1 mV to 500V. AC/DC ^B \ current from O.lpA to 2A. Resistance from « \ 0.1 11 to 2M11. 200 hour battery life. ^B \ The Kit contains all parts needed to ^B construct the multimeter plus assembly ^B , instructions, battery and test leads. ^B We also offer a calibration sen/ice ^B^ — (£5.00 + VAT) and a trouble-shooting and ^B^^ calibration service (£7.50 + VAT). Various other component parts are also available as listed. The multimeter is also available fully assembled and calibrated at a cost of £39.70 + P&P + VAT. iber 1980 -11-01 Car with hybrid drive A team of leading automotive and tech- nology firms from the U.S., West Germany, and Japan is currently pro- ducing two advanced 'hybrid' auto- mobiles for the U.S. Department of Energy (DOE). The experimental vehicles will have both a gasoline engine and an electric motor under the bonnet. They will run part of the time on gasoline, part of the time on batteries, and - when needed — on both simultaneously. This is part of an overall DOE pro- gramme aimed at stimulating commer- cialisation of electric and hybrid vehicles as a means of reducing U.S. petroleum consumption. The hybrid design, for example, is expected to consume from 40% to 55% less petroleum than a conventional car of similar size over an 11,000-mile annual driving mission. General Electric will provide expertise on the electric propulsion motor, the electronic controls for the motor, and the microcomputer controls for the entire hybrid system. Last year, the company delivered to DOE the Electric Test Vehicle-1, the nation's most advanced experimental electric vehicle. Major subcontractors to GE in the hybrid vehicle project are the Research Division of Volkswagenwerk AG, Wolfs- burg, West Germany, which will design and build the specially modified gasoline engine; Globe-Union Inc., Milwaukee, Wiscousin, which will de- velop the advanced 12-volt lead-acid batteries that will power the electric motor; and Triad Services, Inc., Michigan, which will design and fabri- cate the body and chassis. These companies worked together pre- viously, in similar roles, in developing the ETV-1, as well as the GE-100 - an electric test car built from one-the-shelf components. Daihatsu Motor Co. Ltd., Japan's leading manufacturer of battery-powered ve- hicles, will serve as a consultant on the project. The Osaka-based company has built more than 4,000 electric and hybrid vehicles since 1 965. Thanks to its dual drive system, the hybrid automobile is a promising approach to helping the U.S. meet its transportation requirements in the potentially fuel-short years that lie ahead. The hybrid car is designed to minimise trips to the gas station and maximise the use of the wall plug for the typical American driver. Its major advantage is that it burns less gasoline than conventional cars, but offers a much greater range than all-electric vehicles. The hybrid's electric motor and gasoline engine will operate separately or in parallel. The electric motor will primar- ily be used for speeds from zero to 30 mph and the gasoline engine for most highway driving. In situations where both the electric motor and the gasoline engine are needed, such as in overtaking, the load will automatically be shared. A microcomputer will con- trol overall vehicle operation. The baseline vehicle selected by GE for this project is a mid size, four-door car. It will utilise front-wheel drive, with the internal combustion engine and electric motor mounted longitudinally under the bonnet. The complete power train, including batteries, will all be located in front of the forward bulkhead. In addition, the vehicle's exterior will be redesigned for improved aerodynamics. Curb weight of the car is estimated to be about 3,950 pounds. The vehicle will be equiped with an automatic three-speed transmission. The car's ten batteries will have a total weight of 770 pounds, and will have a life expect- ancy of approximately 800 recharge cycles. The battery pack may be re- charged by regenerative braking, by the gasoline engine when it is in operation, and by wall-plug electricity. Although the hybrid will weigh about 800 pounds more than its conventional counterpart, its dual propulsion system will require 5% less total energy. It is estimated that the experimental hybrid auto will accelerate from zero to 50 mph in 12 seconds and will look, perform, and handle like conventional vehicles that will be marketed in the mid-1980s. Its design is planned to be suitable for mass production in the mid- 1980s at a consumer price of about $7,600(1978 dollars). Although no plans at this time exist to manufacture or market electric or hybrid vehicles, long-range opportunities to supply components for the emerging electric and hybrid-vehicle market are foreseen. A report by General Electric, Schenectady, N. Y. (565 SI 1-02 -ele Electronics in Livingston Recent major developments by elec- tronics companies in Livingston have emphasised the town's leading role in this industry in Scotland and given the town a firm base to face the future and encourage the development of further high-technology industries. Throughout this year, electronics firms have shown by their development programmes that Livingston is an ideal location for their operations - be they manufacturing, research and develop- ment, or sales. Two American-owned companies. Burroughs Machines Ltd and MFE Ltd have moved over the summer period into purpose-built manufacturing plants on Kirkton Campus, a special industrial area of 80 hectares which Livingston Development Corporation set up for companies with a high research or technological content in their oper- ations and with the need to have close liaison with universities. A third American company. Guardian Electric of Chicago, have established their European sales and marketing headquarters in an office block in the The Burroughs factory, on a 5% hec- tares site, manufactures data processing equipment for the banking industry and is building up its workforce in the 8,350 square metres factory to around 200 people - many of them university graduates and highly skilled workers. On a nearby site, MFE Ltd have moved into a 2,270 square metres factory — their first manufacturing plant outside North America. They employ around 60 people and aim to increase this to 240 by the end of the next five years. At Livingston they manufacture and market computer peripheral devices, including the high technology floppy disk drive. The success at Guardian Electric Sales and Marketting Co. Ltd., has exceeded the company's expec- tations since they moved into Peel House, Ladywell, in March. Another well-known name to opt for Livingston when looking for a location for a research establishment was Ferranti, who announced earlier this year that they would move their com- puter graphics design facility from Edinburgh to an advance factory on Brucefield Industrial Park, Livingston. The great majority of new companies moving to the town in both the indus- trial and commercial spheres originate from outside Scotland, attracted by Livingston's attractive amenities, its superb links with airports, container ports, railheads and motorways. The hard commercial facts are that Livingston is demonstrably the main industrial growth point in Central Scotland, with easy access to deep water port and container facilities at Leith, Grangemouth and the Clyde ports, and major freight terminals at Edinburgh, 24 kilometres east, and Glasgow 48 kilometres west. Edinburgh Airport is only 15 minutes away by road, and every UK international airport is within 60 minutes flying time. These, in addition to Livingston's situation on the M8 Motorway, are powerful factors in favour of Livingston as a new location for an industry contemplating a move to Scotland. Of the 145 companies already estab- lished in Livingston, more than 20 are involved in the electronics industry. The town's popularity with the elec- tronics industry was explained by Mr I.B. Alexander, engineering director of Marconi Communications Systems Ltd., who relocated a research and development facility in Livingston at the end of 1977. Livingston he said, was ideally situated near Scotland's major universities, and the company had found that there were a lot of graduates emigrating from Scotland. A lot of companies coming to Scotland were not giving the right type of work for these gradu- ates and there was a need to provide an outlet. Marconi wanted an operations base in central belt of Scotland and Livingston's ideal position gave it a very important advantage. Livingston is within easy reach of seven of Scotland's universities. It has particu- larly close links with Heriot Watt University, which is less than ten minutes away by car. Also in close association is the Science Faculty of Edinburgh University. University/industry liaison is also main- tained with Strathclyde University, Glasgow, which has established a Centre for Industrial Innovation. (572 S) New computing centre at Bristol Since the beginning of the year a new £2 million computing centre housed in a purpose-built building has been in operation at British Aerospace Dynamics Group Bristol Division. The main function of the centre is to provide a real-time computing service to scientists and engineers engaged in the design and development of guide- weapon and space engineering systems. The computer is an IBM 3031 with a 4Mb mainstore. Also included in the installation are eight IBM 3350 fixed disc drives and six IBM 3330 demount- able drives giving a total on-line storage- capacity of 3,736 Mb; plus four mag- netic-tape drives, a card reader/punch, two line printers and an IBM 3705 communications controller to which are linked two remote batch terminals and 40 individual input/output ter- minals. The Bristol computer is connected via two 9600 band channels to another British Aerospace Dynamics Group computer - an IBM 370-158 AP (shortly to be replaced by an IBM 3033) - situated at Stevenage which primarily performs commercial tasks with periph- eral units of the Bristol installation being used for data input and output. In addition, the Bristol Division's remote batch terminals can be switched | over two more channels to connect i with another Dynamics Group computer (an IBM 370-158) for engineering and scientific work. The Bristol centre is operated by the 69-member staff of the Management Services Department as a general service I to the British Aerospace Dynamics Group Bristol Division, computing time being logged and charged to the user departments. The key to the operation of the Bristol centre is the 40 individual input/output terminals which are distri- buted thoughout the many sites the Division has in the Bristol area. Each input/output terminal consists of a visual display unit (VDU) with an associated keyboard. With the aid of such a terminal a scientist or engineer can develop and run his own programs in real-time calling up information or other set programs held in the com- puter's store files when needed, as though he were the sole user of the computer system. The computer is under the general control of MVS/SE (Multiple Virtual Storage/System Exten- sions) and the operation of the VDU terminals is organised by the VSPC system (Virtual Storage Personal Com- puter). Fortran, in its various dialects, is the language used for scientific and engineering applications; commercial programs are written in Cobol. Nine Redifon Seecheck terminals linked to a 5 Mb fixed) cannot be followed. The value of R9 depends on the current intake of the motor. A voltage drop of 0.35 (effective) across it is sufficient. Check this with a multimeter. PI sets the required angle. Thus must be done slowly owing to the delay in reaction mentioned before. Check that the setting does not prevent the motor from starting up. C3 determines the inte- gration time and can be increased in value if the motor does not run smoothly. Conclusion The circuit described here shows how much energy can be saved with electronics. When testing it is advisable to use an old motor and to wait until you're absolutely sure it works properly before inserting the circuit into your appliance. Progress continues to be made in this field. It won't be long before an 1C will be available with all the components required integrated on a single chip! The principle of this energy-saving method was invented by Mr. Nola, a gentleman working for NASA. He is bound to have taken out a patent for it. H illuminated by LED D1. The reflected light was detected by the photo darlington T1. The speed may be adjusted with PI. P2 has been added to limit the maximum speed. Cl (4n7) determines the maximum input frequency of 150 Hi. By modifying Cl it is also possible to deal with other frequencies. A frequency that is twice as high will require a capacitor of half the size. C2 determines the regulation constant, the time delay it takes the circuit to react. This must be matched to the motor to ensure smooth running. If C2's size is to be such that an electrolytic capacitor is to be chosen, it is necessary to use two as drawn. coffee machir don't al coflee s mad iln e snilHi Is Did you know that even your coffee machine could save energy? With the aid of this clever little circuit it can make up for its user's forgetfulness, namely, by switching off the hot plate as soon as the coffee pot is picked up. A warning signal is then sounded, so that if the remaining coffee is to be kept warm a button must be pressed. More and more people are taking to drinking coffee these days and coffee machines certainly prepare a good cup efficiently. They even keep your second cup warm for you. The trouble is, you don't always want another cup, which means a fair amount of electricity is going 'down the drain' - 500 watts to be exact. This circuit switches the hot ^ plate off automatically when- ever the coffee pot is re- moved. When it is replaced I a buzzing tone is heard as a reminder that the plate is no longer 'on'. If the coffee is to be kept at drinking temperature a button will have to be pressed. A micro switch is mounted on the machine in such a position that it will be closed when the coffee pot is on the hot plate and open when it is removed. When switching on the coffee machine, the push button has to be operated to heat up the hot plate. This continues until the coffee pot is taken away, it then switches off. When the pot is put back, a buzzer sounds for a second as a reminder that the coffee will no longer be kept warm. If more coffee is to be drunk later, a button will have to be pressed. Then the hot plate will be 'on' until the coffee pot is removed again. In other words, the circuit is an 'active warning device'. First it is activated (switches off) and then it issues a warning (buzzes). The circuit The circuit shown in figure 1 has been kept as small as possible to enable it to be incorporated in the coffee machine. I It can be split into two parts: an elec- tronic zero-crossing switch (everything behind the opto-coupler IC2) and the section in front of it that detects the coffee pot and gives the warning. Switch SI is the micro switch which detects the presence of the coffee pot and is closed when the coffee pot is on the plate. The output of the flipflop built up with N2 and N3 has however not yet been defined. Operating push button S2 causes the output to become low. Then T2 will conduct and LED D3 (optical indication) and the LED in the opto-coupler will light. The thyristor in IC2 can then switch on the triac TR1 via the diode bridge D4 . . . D7. Due to the presence of transistor T3, the photo thyristor can only switch on at the beginning of every half cycle of the mains supply. When the mains voltage reaches about 20 V, T3 will start to conduct causing the gate and the cathode of the photo thyristor to be short circuited so that this will switch off. When the coffee pot is removed, SI will open causing the flipflop N2, N3 to swing round and T2 to close. The photo thyristor will no longer be illuminated and the hot plate will be off. SI will close again when the coffee pot is put back. During the RC time of Cl and R2 the output of N1 will become low so that transistor T1 will conduct and the buzzer will sound. With the values of Cl and R1 chosen here the buzzer will continue for about one second. Depressing S2 causes the output of the flipflop to become low again, T2 to conduct and the triac to switch on the hot plate. Since the position of the flipflop depends on SI and S2, the plate can only be switched on if S2 is operated after the coffee pot has been replaced. The supply is very modest: a small transformer, a bridge, a voltage regulator and a few capacitors. The circuit board and construction The layout of the printed circuit board is shown in figure 2. One half contains the high-voltage section and the other low-voltage section with the opto- coupler between them. If there is enough room in the coffee machine, the board including the transformer can be built in. This is the most simple solution. The primary side of the transformer can be connected to the mains switch of the coffee maker. The two triac connection points on the board should then be connected in series with one supply lead to the hotplate. It should be noted that the triac will require a small heat sink to prevent it from becoming overheated. Push button S2 is mounted on the coffee machine where it can be clearly seen and then a suitable place for the micro switch must be found. This will call for a little experimenting, for the coffee pot is not usually in a fixed position on the plate. It will largely depend on the design of the coffee maker, of course, but one method is given in figure 3 as a suggestion. No doubt our readers will devise other highly ingenious methods, as usual. Should there not be enough room in the coffee machine, the board can be housed in a separate case together with switch S2. This has the disadvantage that it will require a. cable between the machine and the case. It will have to be taken into account that half of the circuit board is carrying supply voltage and so extreme care must be taken. Finally, a word on the buzzer. This is a piezo ceramic type with a low current consumption (only 15 mA). This is the only way to keep the circuit small and yet produce a loud enough tone. H Figure 3. The drawing shows where to place the micro switch. The coffee pot is not in a fixed position on the hot plate, which will have to be taken into account. what is your central heating costing you? If it is known how many hours a central heating system (whether gas or oil) is in operation, it is a simple matter to deter- mine how much energy can be saved by turning off one or several radiators. The number of operational hours can also indicate the correct time to switch from the day thermostat to the night and vice versa. When experimenting with the radiators all that is needed to arrive at the most efficient setting, is a comparison of the number of operational hours before and operational hours counter In the case of a device which only operates now and then, such as a central heating boiler for instance, it may be interesting to find out the true number of effective operational hours. For then the energy consumption per hour or the life of certain components can be calculated. This article describes an electronic operational hours counter which uses very little energy. after adjustment. The different totals of operational hours per 24 hours will be in the same ratio as the energy con- sumption levels to each other. Obvi- ously, the absolute value of the amount of energy consumed can also be calcu- lated. If the heating system is oil fired that will be easy since the heating boiler is usually the only consumer unit connected to the oil tank. The number of litres used can be divided by the number of operational hours in order to obtain the amount of litres per hour. By multiplying that amount with the price per litre, the cost of an operational hour will be found. As far as gas systems are concerned, it is often a little more complicated to calcu- late the price per hour because several systems (gas oven, fire) will be connec- ted to the one gasmeter, so that the central heating system's consumption cannot be calculated separately. One method would be to switch off the other gasappliances, leaving the central heating on, and then read the gas meter for a period of, say, ten minutes. This can also be calculated per operational hour. To find out the central heating costs per quarter the operational hours counter can be used. Figure 1 . The block diagram of the operational hours counter. In order to determine the correct time to switch the thermostat from the day to the night level and vice versa, the minimum number of operational hours in the day time during which the house is comfortably warm can be empirically established. The block diagram Figure 1 shows the block diagram of the operational hours counter. The input of the circuit is connected in parallel to the thermostat switch. When closed, this switch starts an AMV (astable multivibrator) which has an output fre- quency of about 4.5 Hz. Its output signal reaches a divider which divides the signal by 2 14 so that one pulse per hour is available. The output of the counter will be the number of clock pulses in binary. The outputs can be read with LEDs to make the infor- mation visible. Using a single LED for the reading may involve some calcu- lation work, but on the other hand current consumption will be a lot lower. If the LED is used to indicate the out- put information via a pushbutton switch, the power consumption will be The circuit diagram The circuit diagram of the operational hours counter is given in figure 2. Again with a view to saving energy CMOS-ICs are used. When the thermostat switch is open. Cl is charged. A1 will then be closed and the reset input of the 7555 will be grounded so that the AMV will be off. The hours counter will likewise be off. As soon as the thermostat switch closes. Cl will be discharged across R2 opening A1. Pin 4 of the 7555 is then taken high and the AMV will start to operate. Its frequency should be set to 4.5 Hz with the aid of PI . Pin 3 of the 7555 is connected to the clock input of IC2. The Q14 output of this 1C will generate a pulse every hour if the AMV is properly regulated. Thus, IC3 will receive a clock pulse every hour. At the first clock pulse the output QO will become high. At the second Q1 will become high and QO low again and so on in a binary format. For those readers who are not too familiar with binary, the values of all twelve outputs are given in the table. If several outputs are '1 ', the (decimal) values of those out- puts are added to each other. Thus, 000001010010:2+16 + 64 = 82 hours. The LED D3 will indicate which out- puts are high when pushbutton S2 is operated. The switch S3 enables each output to be selected in turn. If a selected output is high, A2 will be closed and the LED will light when S2 is depressed. If an output is low, A2 will be open and the LED will not light, even if S2 is depressed. Depressing SI will cause the counter to be reset and start counting from zero again. Table Q7 06 Q5 04 Q3 Q2 Q1 QO 2048 1024 512 256 128 64 32 The construction Figure 3 shows the printed circuit board on which the circuit can be mounted. The input is connected to the thermo- stat switch by means of wires. The supply can be provided by two or three penlight cells in series or by means of a single 4.5 V battery. The batteries last for quite a long time because the LED of course only has to light occasionally and the quiescent current consumption is not more than 45 pA. Zener diode D2 should have a slightly higher value than the supply voltage. At a supply of 3 volts, 3.3 V is a good value, at 4.5 volts, a 4.7 V zener will be required. The best way to set PI is to use output Q8 of IC2. This output should change in level after about every 28 seconds (1 cycle per 5614 seconds) if PI is cor- rectly set. Once this has been achieved, PI can be locked with glue or nail varnish. The frequency of the AMV is independent of the supply voltage, in other words at lower battery voltages the count will still be correct. The entire unit may be fitted in a plastic case with the switches mounted so that they are easily accessible and the LED placed where it is clearly visible. The circuit can of course also be used to count the operational hours of other devices as well as the central heating. To adapt it to other circuits another two switches (A3 and A4) can be used. The pins 5 and 6 belonging to them will then obviously not be grounded. H Digital readout power supplies Precision power supplies just announced Photodiode arrays for position detection Audio frequency test meters The first ever hand-held digital level meter capable of making weighted and unweighted (16281 Remote control garage door operator The NuTone computerised garage door operator, is now newly available, throughout the U,K„ from the Haos Company Ltd., of Bromley, Kent, It offers advantages over systems already on the market in that it is advanced, both technically and in appearance; more secure.operates from the greater distance of 400 yards; has a computer that does its own adjustments (to help the do-it-yourself installer); and is competitively priced. applications. They measure 317.5 mm (12.5 in) wide. 295.3 mm (11,63 ini deep, and are available in heights from 114.6 mm (4.51 in) to 146.3 mm (5.76 in). Moulded from heavy-weight ABS material the units are attractive, durable, strong, and impact resistant, and use a special system of internal mounting bosses. PC card guides, mounting rails, accessories, and other hard- ware to give the designer the unlimited flexibility in creating precisely the custom enclosure he needs. In addition, he can create an attractive custom with three- dimensionally moulded front panels which can also incorporate production features such as posts, clips and slots. This garage door opener will fit most up-and- over garage doors: it is simply installed by the do-it-yourselfer, (using step-by-step instruc- agent. In response to a signal from the hand control, it has the facility to open a heavy garage door, turn on the light, allowing the driver sufficient time to get out of the car and leave the garage, automatically turn off the light, and close and securely lock the door. The Haos Company L td. The Built-In Centre, Bromley, Kent (tel.: 014602136). (1685 M) Economical medium-size enclosures OK's series CL PacTec enclosures provide instrument and electronics manufacturers and designers with a creative and adaptable, medium- to large-size enclosure package at a considerably lower cost than made-to- measure moulded plastic or fabricated metal The CL enclosures are ideal for oscilloscopes. The range is available in four standard colours — blue, tan. black and grey - plus fifteen special colours. Options include custom trim, special finishes, special bezels, strap handle. EMI and RFI shielding, construction from UL listed material, sloped top or bottom cover, rear panel extensions and card guides and mounting rails. Tilt stands can also be supplied. The CL enclosures enable the user to create prototypes, easily and inexpensively, using low-cost designer kits. Depending on which kit is selected, it can contain top and bottom covers, side panels, front and rear panels (which can be drilled, cut. punched and silkscreened), card guides, mounting rails, hardware and a tilt stand. The user simply selects the size case needed, picks the hard- ware and accessories from the kit necessary OK Machine & Tool (UK) Ltd.. Dutton Lane, Eastleigh, Hants SOS 4AA, Tel: 0703 - 610944. (1678 M) Miniature terminal strip has 7 A rating A series of miniature barrier terminal strips are available for applications in electrical and electronic equipment and instrumentation such as modular power supplies. The M24F is a range of miniature barrier terminal strips offering a wide range of cavity and termination possibilities. While compact in design, they present no compromise to electrical safety; their 3 mm high barriers are proofed at up to 7 A at 6.2 KV. depending upon the types of termination fitted, and permit working voltages of up to 1 KV r.m.s. The overall dimensions of the strip are 8.5 mm high x 16.0 mm deep, with up to 14 cavities on 6.35 mm centres. End fixing is by unthreaded holes, which can be fitted with power supplies, as well as for many other incorporated on the M24F. These include The M24F miniature barrier terminal strip is moulded in either blue galss-filled nylon, or black glass-filled nylon or polyester UL 94 V-0 rated to +120°C, according to application requirements. H & T Components, Crowdy's Hill Estate, Kembrey Street, Swindon, Wiltshire SN2 6BN. Tel. (0793) 693681-7. (1688 M) Flexible copper clad laminates from 3M CuFlex 6550 flexible copper clad laminates - a new range - has been introduced by 3M Group for the production of high quality The CuFlex flexible copper clad dielectric consists of a flexible flame rerardant wpoxy / polyester resin, reinforced by an organic fibre non-woven weg. It has all the properties to provide the highest quality printed circuits. These properties include good adhesion to copper, good thermal and dimensional stability, solder ability, mechanical strength. Other qualities include a high peel strength eliminating the need for covercoats in certain applications, good dimensional stability, high components without rigidising. It can also be wave soldered —without blistering —at 260°C for 1 0 seconds. CuFlex 6550 flesible circuitry is currently being used in military and aerospace applications, computers, instrumentation and in telecommunications. Other major areas of application include telephone handsets, back plane wiring, electronic switching and speaker Products Group, 3M United Kingdom Ltd., 3M House. PO Box 1, Bracknell. Berks RG12 1JU. Tel.: (0344) 58436 (1686 M) the quadrant QD50-5T element hybrid OSI - 5K. / PP 65 - 25 having optical ir 25 cm length of plastic fibre Centronic, Centronic House, King Henry's Drive. New Addington, Croydon, CR9 OBG England. Tel: (06891 42121/8 ranges and accuracy is 1%. True R.M.S. • measuring circuits are used enabling accurt determination of distorted waveforms su as thyristor outputs. Single phase and b anced three phase circuits may be monitor) New two-tone brown case boxes To complement their comprehensive range of two-tone grey plastic Veroboxes, Vero Electronics Limited have introduced two models in an attractive two-tone brown colour scheme. The first is a Type I Verobox with an overall width of 205 mm, height of 75 mm and depth of 140 mm. Consisting of a top and bottom section held together by four screws which enter through the plastic feet located on the base, it includes front and rear panels and ^ n prevailing on the workshop floor. Its advanced semiconductor technique makes it also intensitive to surrounding electronic and magnetic interferences, which previously caused serious problems with other electronic 66. High Street, Houghton Regis, Dunstable, Beds. LU5 5B England, Tel.: Dunstable 68 181 f Precision planetary gearbox A new gearbox has been designed and made utilising the very latest available technology. Knows as the R22 precision planetary gearbox, it is available with two or three gear stages and a range ot six different ratios from 16.2:1 to 190:1. It has torque rating of 0.6 Nm (85 oz. ins). The diameter is 22 mm; for ratios up to 33.1:1 the length is Sinclair Electronics L td., London Road. St. Ives. Huntingdon, Cambs PE 17 4HJ, Tel: 104801 64646. TM352 - New hand held LCD multimeter from Thandar Sinclair Electronics announce the latest prod- The unit is designed for uct in the Thandar range of low-cost, portable temperature range -40 ( test equipment. The TM352 is a battery assembled in a low prc operated 3% digit hand-held multimeter with package for applications a large 0.5" liquid crystal display. With an range finding, laser pro input impedance of 10 MO. it covers fibre-optic communication 16 ranges, including DC voltage IIOOpV - Centronic. Centronic Horn 1000 V), AC voltage (1 00 mV - 1 000 V), King Henry's Drive, DC current UOOnA-lOA), resistance New Addington, (1 12- 20MI2). Also featured are an audible Croydon, CR9 OBG England. continuity check and an hFE measurement Tel: 106891 42121/8. designed lor operating over the range -40°C to +70 C and is i a low profile isolated TO-5 To ensure reliable and trouble-free operation, the R22 is made with hardened steel shafts and pinions and the stainless-steel output shaft runs in pre-lubricated sintered bronze housing are moulded from synthetic materials. This new gearbox can be fitted to the 22, 23, 26 and 28 PL series of d.c. motors. Portescap IU.K.I Limited, 204 Elgar Road, Reading, RG2 ODD. Tel: 10734) 861 485/6/7/8 . DILswitch modules The Erg SDC4 DILswitch module contains four, two-pole changeover dual in-line switches. Each switching member has its own, unique colour and is also individually num- bered. This, together with the comparatively components very easy to use. The status of all switches is also very quickly distinguished at a glance. All switches have contact ratings of High-accuracy Sample-Hold amplifier Precision Monilithics introduces the SMP-1 1 a date-acquisition sample-and-hold amplifie featuring 0.015% accuracy and a lov combined offset voltage and step transfe error of 0.45 mV. The SMP-1 1 employs i SL 1600 series Plessey application design by James Bryant - modified to accept an 8-pole 10.7 MHz SSB crystal filter to enable the frequency offset of the system to be used with the Ambit DFM 7 LCD frequency readout module for 1 kHz resolution in the HF bands. 10 kHz to 100 MHz may be spanned - although for most users, the standard 1 - 500 MHz range is quite sufficient. The unit and thus enables the unit to be from English text. Although th rapidly programmed, and also extremely useful 'to the blind. Costronics Electronics, and bandpass SERVICES TO READERS EPS print /cruicc Many Elektor circuits are accompanied by printed circuit designs. Some of these designs, but not all, are also available as ready-etched and pre-drilled boards, which can be ordered from any of our offices. A complete list of the available boards is published under the heading 'EPS print service' in every issue. Delivery time is approximately three weeks. It should be noted however that only boards which have at some time been published in the EPS list are available; the fact that a design for a board is published in a particular article does not necessarily imply that it can be supplied by Elektor. Technical quctic/ Please enclose a stamped, self-addressed envelope; readers outside UK please enclose an IRC instead of stamps. Letters should be addressed to the department concerned - TQE (Technical Queries). Although we feel that this is an essential service to readers, we regret that certain restrictions are necessary: 1 . Questions that are not related to articles published in Elektor cannot be answered. 2. Questions concerning the connection of Elektor designs to other units (e.g. existing equipment) cannot normally be answered, owing to a lack of practical experience with those other units. An answer can only be based on a comparison of our design specifications with those of the other equipment. 3. Questions about suppliers for components are usually answered on the basis of advertisements, and readers can usually check these themselves. 4. As far as possible, answers will be on standard reply We trust that our readers will understand the reasons for these restrictions. On the one hand we feel that all technical queries should be answered as quickly and completely as possible; on the other hand this must not lead to overloading of our technical staff as this could lead to blown fuses and reduced quality in future issues. CONDITIONS OF ACCEPTANCE OF CLASSIFIED ADVERTISEMENTS 1. Advertisements are accepted subject to the conditions appearing on our current rate card and on the express understanding that the Advertiser warrants that the advert- isement does not contravene any Act of Parliament nor is it an in- fringement of the British Code of Advertising Practice. 2. The Publishers reserve the right to refuse or withdraw any advert- isement. 3. Although every care is taken, the Publishers shall not be liable for clerical or printer's errors or their consequences. 4. The Advertiser's full name and address must accompany each advertisement submitted. The prepaid rate for Classified Advertisements is 13 pence per word (minimum 12 words). Semi- display setting £4.40 per single column centimetre (minimum 2.5 cms.). All cheques, postal orders, etc. to be made payable to Elektor Publishers Ltd. Treasury notes should always be sent by registered post. Advertisements, together with remittance, should be sent to the Classified Advertisement Manager, Elektor Publishers Ltd., 10 Longport, Canterbury, Kent CT1 1PE. FREE 1980 AMTRON Catalogue with new range of kits and equip- ment cabinets. Send S. A. E. to AMTRON UK LTD., 7 HUGHENDEN ROAD, HASTINGS, SUSSEX TN34 3TG. Telephone Hastings 436004 CLEARANCE PARCELS : TRANSISTORS, RESISTORS, BOARDS, HARDWARE, 101 lbs. - only £5.80! 1000 RESISTORS £4.25 500 CAPACITORS £3.75 BC108, BC171, BC204, BC230, 2N5061 , CV7497 TRANSISTORS 10 70p 100 £5.80 2N3055, 10 for £3.50. S.A.E. for lists : W.V.E. (4), 15 HIGH STREET, LYDNEY, GLOUCESTER. PRINTED CIRCUITS. Make your own simply, cheaply and quickly! Golden Fotolak Light Sensitive Lacquer now greatly improved and very much faster. Aerosol cans with full instructions - £2.25. Dev- eloper - 35p. Ferric Chloride - 55p. Clear Acetate sheet for master 14p. Copper-clad Fibre-glass Board approx. 1mm thick - £1.75 sq. ft. Post & Packing 60p. WHITE HOUSE ELECTRONICS, P.O. BOX 19, PENZANCE, CORNWALL. 50 MIXED TRANSISTORS 95p extra thin copper plated fibre board 72 square inches 90p: Lists 15p SOLE ELECTRONICS (ELKR), 37 STANLEY STREET, ORMSKIRK, LANCS. L39 2DH. Breadbord '80 UK 15 S. & R. Brewster UK 10 British National Radio & Electronics School UK 17 Codespeed Electronics UK 08 Coiltronic UK 21 Doram Electronics UK 07 Electrovalue UK 20 Keytronics UK 14 Lascar Electronics UK 12 Maclin-Zand Electronics UK 11 Maplin UK 02 Marshall's UK19 Microcircuits UK 09 G.F. Milward UK 19 Monolith Electronics UK 17 Orbit Electronics UK 19 Phonosonics UK17 T. Powell UK 26 Ramar UK 21 Safgan Electronics UK 19 Suretron Systems UK 21 Technomatic UK 25 TK Electronics UK 08 Do you need electronic components- tools-test meters etc. YES! - Then send 30p for our catalogue to: LIGHTNING ELECTRONIC COMP- ONENTS, Dept ELK, FREEPOST, TAMWORTH, STAFFS. B77 1BR. ELEKTOR up TV GAMES COM- PUTER Program Exchange! Please send me your typewritten program lists (plus a self-addressed envelope, A4, 2 International Reply Coupons, and a handling charge of £3) and I will collect, print (offset), and return to you copies of all the best games sent to me. In this way we can cheaply have many more games to play with. Please write to: MR. P.J. WALKER, AN DER SCHANZ 2 (17/3), 5000 COLOGNE 60, W. GERMANY. TUNBRIDGE WELLS COMPONENTS at BALLARD'S. 108 CAMDEN RD„ Tel. 31803. No lists, SAE for enquiries REQUIRED: WORKSHOP ENGINEER familiar with repairing Micro Processor Controlled System. Experience welcome, but not necessary. Please write to: VIDEO GAMES SALES, 24 LANGROYD ROAD, LONDON SW17. PLEASE NOTE : FROM 1st NOVEMBER 1980 THE RATE FOR CLASSIFIED AD- VERTISEMENTS (PREPAID) WILL BE INCREASED TO 20 PENCE PER WORD (MINIMUM 12 WORDS). SEMI-DISPLAY SETTING WILL BE INCREASED TO £5.50 PER SINGLE COLUMN CENTIMETRE (MINIMUM 2.5 CMS).