We found this circuit in the January 1978 issue of Radio Electronics magazine. The integrated circuit is from that time and is powered by a 9 V battery. The signal must be applied to an amplifier.
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....