Found in 1980s Electronic Engineering, this circuit uses common phototransistors as sensors. The circuit is CMOS using an integrated 4011.
This circuit was found in a 1964 documentation. It shows how to achieve automatic gain control for...
Incredibly, a 78XX type voltage regulator can be used to amplify low frequency (audio) signals in the...
This power supply protection circuit was found in the December 1978 Radio Electronics magazine. The SCR...