This circuit is from a Radio Electronics from April 1964. The circuit uses power transistors of the time, which must be mounted on a good heat radiator. Modern equivalents can be used.
Found in American documentation from the 90s, this circuit passes frequencies above 1 kHz. The...
Found in a documentation by Hugo Gernsback from 1960, this receiver uses germanium transistors of the time...
The oscillator shown in the figure generates a 1 kHz tone that is reproduced on the speaker with...