power MOSFETS in the car

simple swinging poster The original "swinging poster" circuit was published in the January 1981 issue of Elekta disco etc. As the circuit is rather expensive to build and most readers prefer to see the particular visual effects before actually "forking out" for such a project, a much simpler version has been designed. The majority of this control circuit can be constructed from the comPonents that can be found in the so-called "junk box". Two thyristors and a single CMOS IC are used so that the circuit can be powered directly from the mains. To avoid any mains interference the circuit is only activated at the zero-crossings of the mains" voltage. The power supply for the circuit is derived will only go low for a short period when the mains voltage is somewhere around 0 V and pin 1 of N1 is high. Transistor T2 will then stop conducting and thyristor Th2 will be activated via resistor R3 for one half-cycle of the mains frequency. The same thing will of course happen with thyristor...