DC/DC converter

In circuits where two signal paths must be electrically isolated, use is often made of an opto-coupler. Unfor- tunately, these devices require two power supplies: one for the sender, and the other for the receiver. In industrial and professional undertak- ings this requirement is met by a pro- prietary. DC/DC converter. As these are by and large very expensive, they are not of very much interest to the average hobbyist. However, the do-it- yourself converter presented here is much less expensive and, moreover, easy to build. The circuit diagram in figure 1 shows that the converter consists of an oscil- lator, IC1, and a driver, IC2, on the primary side, and of a rectifier, D1... D 4, and buffer capacitor, C3, at the secondary. In our prototype, operating from a 12 V battery at the maximum 74 per cent efficiency, we measured a sec- ondary output voltage of 10.64 V, and a secondary output current of 9 mA (the corresponding primary current amounted to 10.8 mA). The second- ary curren...