[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. The ...

Why not create your very own high speed camera trigger using a Arduino, piezoelectric sensor (as a sound sensor), a DSLR camera and an external flash.

You'll definitely need some gear for it—the Arduino for one, but also a PIR motion sensor, not to mention the (cleaned and rinsed!) Raid Power Sprayer motorized spray bottle.

Three devices including a quad Schmitt Trigger and a Flip-Flop make a proximity sensor.

[Dustin Andrews] built this add-on board which works as a proximity sensor. He wanted a standalone sensor for his Arduino projects which would use a single pin as a trigger. This lets him alert ...