Slotted optical flag switch,OPB680

The OPB680 slotted optical flag switches, from Optek Technology, are designed for PCB mounting. They consist of an NPN phototransistor and an IR LED within a black plastic housing. They have an enhanced low current roll-off which improves the contrast ratio and block out ambient light.
The light beam can be interrupted using the arm (flag), switching the transistor output between states that can readily drive logic gates.