What this part is and what it does
Omron EE-SX1042 is a through‑hole phototransistor sensor with a 5 mm gap width and 0.5 mm aperture. It's designed for presence/absence detection of opaque objects in compact spaces—think card readers, coin hoppers, or interposer position checks. The phototransistor output switches with incident IR, so you get a clean digital signal off a simple pull‑up. Forward current 50 mA, reverse voltage 4 V, forward voltage 1.2 V. RoHS compliant.