This simple step of low power audio is from a 1975 documentation. The transistor can be a BC548, and the transformer of the type found in small transistor radios and recorders of the time.
This circuit was found in the November 1993 issue of Electronics Now magazine. The two-stage...
This circuit acts on a relay disconnecting the load when the input voltage exceeds the set limit....
This circuit is from a Radio Electronics from March 1970. The integrated circuit used is one of...