This simple circuit, found in American documentation, uses only one relay that locks when any of the sensors is activated. To reset, simply turn off the power for a moment.
This low frequency oscillator with an operational amplifier of type 741 has adjustment of the mark...
The circuit shown in the figure is suggested by National Semiconductor and makes use of an...
This circuit was obtained in a technical documentation from 1997. In the event of a power failure, it...