Make Your Own Laser Tachometer for $10

Laser tachometers are able to measure how fast something is rotating by sensing a reflective surface as it whizzes by. While cheap laser tachs can be had for $20 or so, if you’d rather produce your own, you can construct this model by Elite Worm with an Arduino clone, laser, and sensor for about half that cost. You’ll also need a 3D printer for the housing, though you could probably get creative if one’s not available.

The video below goes over the build process in some detail, which involves hooking the Arduino up to a small I2C OLED display, along with a single interface button to start measuring. A small laser diode is also soldered onto a detector PCB and attached to the Nano, allowing it to measure reflections.

As seen in the demo starting at just after 4:40 in the video below, the DIY tachometer shows roughly the same values as a commercial version, and even provides a better refresh rate.

If you’d like to make your own, code is available on GitHub and an STL for the physical design can be found on Thingiverse. Notably, Elite Worm did a great job modeling everything in place, so you’ll be using screws instead of hot glue if you follow his mechanical design!

[h/t: Reddit]