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. ... (Arduino Uno/Nano Sketch)… [code] ...

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.

This sensor gives logic high (H) output when an object comes close to the sensor. This sensor only responds to 38 KHz modulated infrared light which makes it immune to disturbance caused by the ...