This receiver for a modulated light intercom was found in a 90s Elektor. The audio amplifier can be replaced by an equivalent. The sensor can be any phototransistor.
The indicated circuit performs a slow charge of 12 V batteries maintaining a constant current of...
Found in a 73 magazine from the 1980s, this circuit generates signals from 3.2 to 22 MHz. FETs can be...
In the figure we have a three-phase AC motor control for voltages up to 600 V or 1200 V depending on...