A simple breakout PCB for the CNZ1120 Photo Interrupter. This PCB has three connections for PWR (3V-6V), GND, and Signal. When the gate is clear, SIG will be low (<0.5V). When the gate is blocked by a finger, writing utensil, food pellet, or anything else - SIG will go high (>4.5V). Assembled picture is for reference only. Parts are listed below. 220 or 330Ohm resistor will work.