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.
Stop breadboarding and soldering – start making immediately! Adafruit’s Circuit Playground is jam-packed with LEDs, sensors, buttons, alligator clip pads and more. Build projects with Circuit Playground in a few minutes with the drag-and-drop MakeCode programming site, learn computer science using the CS Discoveries class on code.org, jump into CircuitPython to learn Python and hardware together, TinyGO, or even use the Arduino IDE. Circuit Playground Express is the newest and best Circuit Playground board, with support for CircuitPython, MakeCode, and Arduino. It has a powerful processor, 10 NeoPixels, mini speaker, InfraRed receive and transmit, two buttons, a switch, 14 alligator clip pads, and lots of sensors: capacitive touch, IR proximity, temperature, light, motion and sound. A whole wide world of electronics and coding is waiting for you, and it fits in the palm of your hand.