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 a Radio Electronics magazine from August 1963. The transistors are...
In the figure we have a circuit in which the second tone recognizer remains disabled until the...
This circuit was found in a 1980 publication. This circuit converts a triangular input signal into...