Hacking a Mouse for Encoders

Keywords: incremental encoder, mouse, hacking, quadrature, infrared emitter, detector, position, rotation, odometry

Incremental optical encoders can be quite expensive. The bottom two photos are commerically available units from US Digital. The left is a $7 USD mylar encoder disk and the right is a $50 USD encased encoder. A US quarter is shown for scale.

Taking apart the ubiquitous $5 PC mouse (top left), however, can give you two cheap but quite reliable encoders plus two infrared (IR) emitter-detector pairs. This tutorial will show you how to take apart a mouse, remove these parts and protoboard your own quadrature encoder (top right) in an afternoon or two.

This tutorial is broken down as follows: