Hi,

Why not use a ball bearing computer cooling fan with speed signal output?
(A PC cooling fan with tachometric signal output).

* * *

Fan Speed Control is Cool!
http://www.maxim-ic.com/appnotes.cfm...te_number/1784


If your PIC is too busy, use a I2C fan controller.

MAX6650 I2C fan controller
http://pdfserv.maxim-ic.com/en/ds/MAX6650-MAX6651.pdf

Best regards,


Luciano