This circuit reminds the driver when he removes the keys from the ignition, leaving the lights on. The circuit is from an August 1974 Radio Electronics magazine.
For those who like experimental circuits, here is a sequential flasher system with LEDs, which can be...
This circuit can be used in broilers, greenhouses, drying chambers to regulate the temperature in a simple...
This circuit consists of an electrostatic sensor that can check if a cable is energized by simply...