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 ended up using a microcontroller and a piece ...

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. The main ...

This tutorial will guide you through the process of building a tachometer around an Arduino. Tachometers are used to measure rotation rate in Revolutions Per Minute (RPM). You don’t need much… ...