On Apr 10, 2008, at 11:18 AM, Nicola Perotto wrote:
> But harddisk motor has 4 wires! So i have some doubts on these!

check out "Y" (sometimes "wye") vs "delta" configuration of the  
windings for brushless three-phase motors.  Your four-wire motors are  
probably Y configured, while the Delta motors seem to be more  
common.  The hard disks I've take apart seem to run about 50/50. (CD  
drives are almost always Delta.)

BillW

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