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.
Found in National Semiconductor documentation from the 1990s, this circuit corrects the curvature of...
Developed by Philips this 60's circuit uses a transistor of the time, but the configuration holds true for...
We found this circuit in an American 1980s documentation. The transistors can be equivalent as BC548...