This circuit, which can be used as a shield, was found in General Electric documentation from the 1980s. The coupler uses a photo-SCR. The circuit admits equivalent components.
This TTL circuit was found in the December 1990 issue of Radio Electronics magazine. The circuit has...
Found in an Electronics World of 1968 this circuit can use any SCR and diodes depending on the...
Placed near a telegraphic transmitter (CW) and with a small antenna or pickup, it reproduces the...