This circuit was found in documentation for radio amateurs of the 1980s. This is the so-called roger-beep, which is the beep that is transmitted when the talk-listen function is changed.
This circuit was found in an American documentation from the 60's. The transistors are from the...
The dual operational used in this sound effect that separates the signal into two tracks is not...
The circuit shown was found in a 1967 RCA manual. Modern equivalent components can be used. The...