The circuit shown in the figure can be designed with more modern operational amplifiers, as it is from 1994 documentation by National Semiconductor. The power supply must be symmetrical.
We found this circuit in a 1988 publication. A touch of the sensor causes the relay to trip and...
This circuit was obtained from a 1968 documentation and can be adapted to use current equivalent...
There are several manufacturers of the integrated circuit used and it also admits equivalents. The circuit...