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 is from a European publication from the 70s. The transistor used is from the time and the...
A Popular Electronics from the 90's suggests this circuit that is based on a low voltage...
We found this circuit in a publication from the 90s. The circuit has a tuning range of 500 to 1...