Photogate

Description

The photogate board functions as an optical sensor for calibrating the absolute position of stepper motors upon controller startup (L0005). The photogate is mounted on the stepper motor adjacent to the motor shaft, which is coupled to the stem of a ball-valve used as the main propellant valve in SDR's liquid engine. The photogate uses an infrared LED to produce an optical signal on the infrared-sensitive phototransistor surface. The board has a characteristic U-shape that allows a small standoff strut on the motor coupler to block the optical path of the sensor when the valve reaches the closed position.

Sources and Documentation

PCB Design Files: GitHub

3D Model: Photogate.step