[mircemk] shows how to create a simple non-contact proximity sensor using little more than an Arduino Nano board, and a convenient software library intended to measure the value of capacitors.

We’ll demonstrate this sensor using a single resistor and a multimeter. Sharp GP2Y0D02 fixed 80cm IR proximity detector (Digikey #425-2064-ND, $14.38). Datasheet (PDF). The GP2Y0D02 requires a ...