Found in a Popular Electronics from the 90s, this circuit can act as a transmitter for an audio link. The output transistor admits a higher power equivalent, depending on the LED.
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...