This circuit was published in an article in Electronics Now magazine in October 1995. The circuit includes a power supply. The power transistors are equivalent.
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...