This circuit uses two relays that switch when the voltage exceeds the value given by zener D2. The circuit is from a Radio Electronics magazine from April 1975.
This circuit, which appears at other points on this site, can be designed with both 4011 and 4001...
We found this circuit in an American documentation from the 90s. The circuit applies to vehicles...
Found in Motorola documentation from 1967, this circuit shows how it is possible to obtain a...