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.
We found this circuit in an Analog Devices documentation from the 90s. The circuit is based on a...
This circuit turns off a load after an interval of 8 to 80 seconds adjusted on the potentiometer. The...
Found elsewhere in this section, this circuit is from the April 1971 Radio Electronics magazine. Note...