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 is an improved circuit from the earlier version also found in the April 1972 Radio...
We found this oscillator in a 1978 amateur radio documentation. The circuit supports other...
This circuit is from an old publication on operational amplifiers. The circuit can be developed with...