Arduino tachometer used to calculate the rotational motion of a part. Tachometers read out revolutions per minute (RPM), which tells the user how often a rotating part completes one full rotation. RPM readings are used in the automotive, aerospace, and manufacturing fields. Tachometers can indicate fuel consumption and motor speed, safety of moving parts, and even wind speed indicators. In this tutorial, the speed of a fan is measured using a hall sensor and neodymium magnet to acquire an accurate depiction of fan speed.

Capacitive sensing from human touch. Create a switch without any moving parts with an Arduino board and an inexpensive capacitive touch sensor.