We found this circuit in the March 1984 issue of Radio Electronics magazine. The module used is a common type at the time. The other integrated circuits are common types.
A narrow range of frequencies around 1 kHz is rejected by the high Q filter shown in the figure,...
This simple converter does not use a transformer and the transistor can be the BD135 for currents up...
This is a circuit from the time when some still called the transistor a crystal triode. It...