This circuit works like a solid-state contactor. We find it in General Electric documentation from 1965. SCRs can be modern equivalents according to the controlled load.
Found in a 1968 documentation, this small amplifier was very popular at the time being used in...
This simple audio signal tracer or follower can be made with a BC548 instead of the original...
According to the 1990 documentation in which we found this circuit, the chickens must be fed at...