Found in a Popular Electronics from the 90s, this circuit uses common components with several operational options, including the use of an optocoupler that allows its application in a shield.
This circuit for telecommunications was found in a 1987 documentation. Connected to the...
This circuit is from a 1966 American documentation. The circuit uses a photo-FET, an unusual...
Currents up to 1.5 A can be regulated with this circuit. The resistor R that determines the...