Magnetic Tachometer for 755 775 Motors

thingiverse

This is a two-channel (I,Q) magnetic tach for popular 755 and 775 DC brushed motors. It's an extremely low-cost solution, costing less than $1, and can operate at very high RPMs while providing accurately phased, glitchless I and Q outputs. The same design approach can be used to create an incremental panel-mounted encoder for digital control. A more detailed PDF file is included in the files, along with a Solidworks source file. Revisions: 11/12/2017: Revised pdf uploaded with minor spelling and wordsmithing changes. 11/15/2017: After experimenting with parameters, I found that scaling on the magnet circle diameter doesn't work well. The generation of magnets for appearance also didn't work with different values of N. To fix this, simply disable the feature for the latter, and I'll create a version that makes it easier to change the magnet circle diameter. 11/18/2017: Replaced the Solidworks file with a revised version that greatly improves parametric range. The magnet circle diameter can now range from 24mm to over 50mm while producing proper results, and the magnet generation issue is fixed. 11/19/2017: Corrected the file name on the Solidworks file to accurately reflect the magnet size.