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 circuit was obtained in the publication 101 Electronics Projects of 1979. The circuit can be...
If you have an old cassette player or bought one from a junk shop, you can set up a small table...
This circuit was found in a 70s American documentation. The converter can be of any type and the...