This circuit was found in the July 1978 issue of Radio Electronics magazine. The circuit uses a common digital voltmeter as the indicator. The sensors are integrated circuits of the time.
This circuit activates a water pump when the sensors detect lack of humidity in a vessel, for...
This circuit was obtained from an Electronics World of 1969. General-purpose transistors can be...
This circuit was found in many record players with crystal phono pickups. The output power is 800...