This circuit was obtained from American documentation from the 1990s. The transformer can be a car ignition coil that works like an autotransformer. Q2 must be equipped with a heat sink.
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...