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.
We found this circuit in a publication for radio amateurs in 1974. The bipolar transistors can be...
Found in a 1980s American documentation, this circuit has a current consumption of only 1 mA. The...
This adjustable power supply was found in Ferranti's transistor manual from 1974. Power...