Object presence and displacement detection circuit

Object presence and displacement detection circuit

Shown is a detection circuit for detecting the presence and displacement of objects . The light-emitting diodes and photosensitive transistors are placed on both sides of the object. The light is blocked by the object. When the object disappears, the light will shine on the phototransistor , so the photosensitive tube is turned on. The voltage at the inverting input terminal of the operational amplifier 1PC177 decreases and outputs a high-level signal .