This circuit triggers an alarm in the event of a power failure. The circuit is from an 80's documentation, being powered by 9 V battery. The parts are common today.
Epson SG 8018 Epson Crystal Programmable Oscillators Available from Mouser Electronics, these...
When the lights turns off this circuit will produce a sound like a cricket. When the lights are...
This circuit appears elsewhere on the site. The circuit shown is from an American 1980s...