Fairchild Semiconductor QCK4 - PHOTODARLINGTON OPTICAL INTERRUPTER SWITCH PHOTODARLINGTON OPTICAL INTERRUPTER SWITCH QCK3 PACKAGE DIMENSIONS 2 C L 3 QCK4 PIN 1 CATHODE 0.2200 PIN 2 ANODE PIN 3 EMITTER PIN 4 COLLECTOR C L Rating: 1 ★ (2 votes)