We found this circuit in a 1991s PE Hobbyst Handbook. The circuit fires 10 LEDs that can control incandescent lamps according to their maximum current.
This circuit is from Radio Electronics. The magazine no more exists, but the circuit can be...
Found in a 1990s US publication, this alarm circuit detects when a light beam is interrupted. Optical...
This telephone circuit was found on a 90's EDN. It keeps a flashing LED to indicate that there was a...