This circuit is from a 1964 Electronic Design book that presents application ideas for transistors. The circuit uses a transistor from that time, but modern equivalents can be used.
This circuit has an LED indication of the timing progress, having been found in an old...
This circuit is from a Radio Electronics magazine from August 1974. It used one of the first...
This charger is powered by the car's 12 V socket, the number of diodes being calculated according to...