Found in a 90s documentation, this circuit makes use of D1, a switching diode that is uncommon today. D3 is an LED. The circuit monitors 12 V batteries.
This circuit was found in a Popular Electronics of June 1978. The circuit is interleaved between the...
To protect your home, vehicles or even objects, what we present is a sensitive alarm circuit that...
This circuit was obtained from an English magazine from 1979, but can be easily assembled...