This drum amplifier was found in an American documentation from 1947. It makes use of a mechanical vibrator to generate high voltage for the tubes.
This small commercial radio for the MW band with germanium transistors was found in Japanese...
This circuit is from 1992 documentation. The transistor can be a TIP42 with a good heat sink for...
This speaker overload protection circuit was found in Radio Electronics from the 1980s. The...