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 was found in General Electric's 1965 documentation. It appears elsewhere on the site....
Found in National Semiconductor documentation from the 1990s, this circuit employs basic...
This receiver amplifier (booster) is from American documentation from the 1970s. The integrated circuit...