Getting a magnetic field to balance on another magnetic field is about as easy as balancing a bowling ball on the tip of an ink pen. With a little help from an Arduino mega, however, [EmmaSong] was… ...

The Hall effect sensor monitors the field of the permanent magnet and uses that information to modulate the magnetic field of the electromagnet, with everything being crunched by the Arduino.

The system here uses a cheap Arduino board, a few sensors, and a magnetic contact switch. It’s then hooked into the Adafruit IO and connected to IFTTT, so you can set up alerts in any way you like.

Scratch Duino is reliable and designed to work under tough conditions: each sensor is protected by its individual plastic shield that can be mounted onto the motorized platform in a foolproof way.