The output transistors can be BC548 and BC558. The circuit is from a 1975 documentation showing a frequency response from 90 Hz to 12.5 kHz.
This circuit was found in an American publication called Ham Radio. The circuit uses still current...
From an audio signal, this circuit gets two signals of the same amplitude and opposite phases....
Found in an Electronic Design from 1968 this circuit generates a linear sawtooth signal modulated...