Test Your Limit (Switches) with This Clever Fixture

Microcontroller processing speeds continue to advance, along with wireless communication capabilities, and home manufacturing tools like 3D printers and laser cutters. For many automation tasks, however, we still rely on the humble microswitch. This type of sensor was first implemented in the 1930s, and can be made to endure millions of on/off cycles.

While we mostly take these little devices for granted, what if you want to make sure they’re working correctly, or even compare the performance of one brand over another? You could hook something up with a battery and LED or similar and push it manually, but this testing machine from YouTuber “Mr Innovative” presents a clever automated option. It employs a stepper motor to spin and push the switch a set number of times, keeping track of the NO (normally open) and NC (normally closed) signals sent the unit’s microcontroller. Assuming the stepper works properly, the number of pushes can then be compared to the number of spins.

The machine is controlled with an Arduino Nano, and a rotary encoder is used to input the number of servo spins/microswitch pushes. Whether the switch passes or fails is then declared on its small OLED display. Although you may not need to do this sort of testing, it’s a visually entertaining project — seen in the video below. If you do want to build your own, the code and circuit design can be found here and print files are up on Thingiverse.