This circuit is based on a regulator component that consists of a transistor and zener in the same package. The circuit can be designed with the equivalent discrete configuration. The current is 200mA.
The oscillator shown in the figure keeps its frequency constant in an active cycle adjustment...
For bench use, this circuit functions as a bistable safety switch. The circuit is from a Radio...
In fact, this is the circuit also known as “vox”, that is, a relay triggered by sound. This...