This old configuration of an audio amplifier has a push-pull two-transistor output stage. Output power is low and the critical components are the transformers. The circuit was found in an 1958’s publication.
This signal follower is from a 1970's documentation. So it uses the traditional configuration at the time...
This is the receiver for the previous circuit. The audio amplifier supports equivalents. The...
This circuit is from 1980 documentation but can still be assembled today with BC548 transistors. The...