This circuit is from General Electric from the 80s, using a relay with high current contacts (20 A). The transistor admits equivalent, and any phototransistor can be used as a sensor.
We found this receiver on a single chip in the 1976 Siemens integrated circuits manual. The...
Found in Radio Electronics from the 90s, this circuit has several outputs with different pulse...
We found this circuit in an English publication from the 60's. The transistors are of germanium of the...