I recently had to build an infrared close proximity sensor that could tell if something was dropped in a parcel delivery drop box. After some searching, I ...

Posted in Arduino Hacks Tagged A4988, arduino, dispenser, ir sensor, label, NEMA-17, stepper motor, sticker ...

The part list consists of one Arduino, two resistors, and one IR emitter. That’s right, an emitter. When an LED (IR or otherwise) is reverse biased it can act as a light sensor.