This circuit automatically turns off small battery-powered devices after a certain amount of time, saving battery life. We found it in a Popular Electronics from the 90s.
This common transistor-based circuit provides power for 20 mA common white LEDs from a single 1.5...
This circuit for old cars with platinum ignition was found in Radio Electronics magazine from...
The receiver shown above was sent in by contributing reader Adriano Muniz Moura and is used for...