This circuit uses a wire potentiometer, but the current is much more intense in the control thanks to the 2N3055 which must be mounted on a heat sink.
This version of the circuit is from 2000, using a source of negative voltage that allows to obtain...
This somewhat complex circuit was found in the May 1984 issue of Radio Electronics magazine. The...
This basic circuit is from an old documentation. The relay must be 50 mA maximum and must have a...