Found in 90s Popular Electronics, this circuit produces a modulated infrared beam for a remote phone whose circuit is shown right after it. Infrared LEDs are common.
This 1980s circuit was found in Motorola documentation. The circuit uses period components that admit of...
This circuit was obtained from old documentation using Intersil components. The circuit provides...
Found in a Radio Electronics from May 1964, this circuit activates a relay depending on the supply...