This circuit uses a transistor to trigger the alarm from a low quiescent current sensor. The relay is 12 V. The circuit is from Radio Electronics magazine, April 1975.
Texas Instruments SN74HCS32 Q1 2-input OR gate This Texas Instruments integrated circuit has 4...
The output voltage is adjusted by the trimpot. The power transistor mist be mounted on a heatsink. The 3.9...
This alarm circuit was found in a 2004 documentation. The circuit searches for open NC sensors....