RC Brushless spindle

[volcano]

My "S-Pid" controller work continues.
Made new sensor today (paper detection sensor salvaged from some old printer, copier...desoldered from its original pcb and added some resistors...) I done some fine tunings and start measuring. I compared my controller readings with
results measured with my standalone tachometer device. Accuracy is far better then i expected. Check the picture!

P.S. So... finding and building a good sensor is done. Accuracy of reading RPM is checked and accomplished, also. Now i will hook an real rc brushless motor instead of this pc fan.
P.P.S. I am aware that what i wrote is far away from spindle mechanical build, but electronic is also
a part of spindle system i want to build, and that kind of spindle speed control is presented in far more expensive rigs. Please tell me if you think i shouldn`t write about this pid controller here, and/or if you like it? Comments are most welcome.
Cheers!