Found in a 90s Popular Electronics, this sensor operates by infrared reflection. The components are modern, and the phototransistor can be of almost any type.
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...