We found this circuit in a Radio Electronics from the 90s. Transistors admit current equivalents, especially the power one that is not a common type today.
This circuit was found in Japanese documentation from the 1960s. It is a commercial circuit with...
This tone control was obtained in the Audio Handbook of the National Semiconductor of 1977. The...
This simple receiver for listening on the phone was obtained in a 1960 documentation. The circuit is...