This filter for receiving audio in telegraphy was found in a magazine 73 for radio amateurs, in an edition of the 80s. The circuit is tuned to 700 Hz and has a 200 Hz bandpass.
We find this circuit in an American 1980s documentation. Integrated circuits are uncommon today as...
The power transistors of this 80's circuit should have at least 10 A current collector and mounted on...
This two-transistor circuit was found in a 1969 US documentation. Modern equivalent transistors can...