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.
Found in a PE Hobbyst Handbook, this circuit checks if there is voltage in a power outlet by...
This circuit was found in an article in Electronics Now magazine from June 1998. The sensor...
This circuit generates an FM signal of 4.7 or 10.7 MHz for audio signals on analog TV or FM, with...