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 new AMS device consists of a digital color sensor and proximity sensor that also incorporates an infrared...
This amplifier produces a few hundred milliwatts of Input 100 pF audio over a load of 4 or 8 ohms...
This transmitter for modulated infrared remote control was found in documentation from the 90s....