February 14, 2009 AT 1:54 pm

DIY hall effect quadrature encoder

So you have a nice little motor and maybe you want to turn it into a robotic project but, alas, it doesn’t have an encoder built into it cause it’s a cheapy thing you found at a swapmeet. Prof. Mason has a nice and simple solution that you can make for $5 and retrofit yourself: a magnet and two hall effect sensors. I bet if you used a Schmitt trigger’d comparator on the outputs you would have a pretty effective encoder that can go straight to your robot brain. I imagine this design is less finicky than optointerrupts + disc. Don’t forget to plug the signals into the microcontroller interrupt pins because they’ll be flying by rather fast!

Is there such a thing as a magnetic set-screw shaft collar? That might avoid the uneven weight problems of gluing a big magnet on.


“D is for Diode” – Circuit Playground Episode 4 is out now! CLICK HERE TO WATCH!

Have an amazing project to share? Join the SHOW-AND-TELL every Wednesday night at 7:30pm ET on Google+ Hangouts.

Join us every Wednesday night at 8pm ET for Ask an Engineer!

Learn resistor values with Mho’s Resistance or get the best electronics calculator for engineers “Circuit Playground”Adafruit’s Apps!



1 Comment

  1. Take ring of the right size, drill a hole for a set screw and one for a neodymium boride magnet epoxy the magnet in place. Steel bond or JB Weld are metal filled and will hold well.

Sorry, the comment form is closed at this time.