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.
This 1989 circuit activates a protection relay if one or two phases are missing from a three-phase...
We found this circuit, quite common in technical publications, in a 1978 documentation. The...
This circuit was found in an American 1980s documentation. The components are current but most...