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 is the decoder circuit for the previous encoder (CB17011E) using integrated circuit MC14028. This...
This simple voltage regulator or stabilizer uses only two component and can source up to 100 mA to a...
We found this preamplifier for the 10 and 11-meter range in an old documentation for radio...