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www.southgatearc.org
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The PW 'Surefire'This project is aimed at those constructors who are unable to-make an electronic circuit work first time. It is hoped that even the most ham-fisted reader should, with little trouble, be able to build and operate this device.
The main function of the circuit, Fig. 1, is to do nothing, a very difficult achievement in a continually changing universe. The circuit layout has been designed so that it would take a very large number of mistakes for nothing not to happen. Should a constructor wish; peripheral devices can be added, but he is warned that too complicated a circuit may do something. The battery was obtained from a transistor radio that did nothing when switched on; this is a good indication of the batteries condition. It should also do nothing when connected across a meter. But to make certain of its integrity a length of wire was connected between its terminals and left for a few hours. The two protection diodes D1/2 were taken from a burnt-out bridge rectifier, but new ones would work just as effectively. The mechanical switch was included because it was felt that a touch switch would have increased the price of the project and may have caused something to happen contrary to the aim of this project. The potentiometers were added to fill two holes in the box used to house the circuit board, but having included them it became apparent that they were a "must", especially when showing the finished product to admiring relatives. VR1 acts as a Kenotron and causes all positrons present in the surrounding
magnetic medium to undergo an adiabatic When the circuit is assembled and switched on, nothing should happen. If, however, something does happen, it is advised that the builder does not take up a career in electronics.
From Practical Wireless, April 1977
Reproduced by kind permission of PW Publishing Ltd
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