This 1969 Electronics World power supply has 5 V to power digital circuits and a 170 V output for Numitron indicator valves used at the time.
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...