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.
The presented circuit can be implemented with a BC548 and for larger currents a BD135 can be used....
This circuit works directly connected to the network and special care must be taken with its...
Suitable for dual applications, this timer was found in a 90s Popular Electronics. The circuit...