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 an English magazine from 1978, but it is still current, just change the...
This is the circuit of a small commercial amplifier from the 1970s from Philips Argentina. The...
This circuit is from a 1965 General Electric hobby manual. The circuit can be assembled with...