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Hard Drive Stepper Motor - with high speed spin-up circuit
Don't throw away that DEAD hard drive just yet...
I had a couple of western digital hard drives lying around that were DEAD. Initially I was going to just harvest the magnets from the drives, but I focused my attention towards the hard drive motor itself instead.
On the left hand side of the image, I just soldered 4 wires to the back of the motor. Normally these contacts make a connection with the circuit board via spring clips. Anyway I placed a black DOT that I will refer to as terminal #1, the others from left to right are #2,#3, and #4.
First I took an ohm meter and measured the coil resistances with the various combination possibilities with their results...
1-2 4.3 Ohms
1-3 4.3 Ohms
1-4 2.5 Ohms
2-3 4.3 Ohms
2-4 2.5 Ohms
3-4 2.5 Ohms
...I looked for the common denominator for the least amount of coil resistance and it worked out to be #4 ... so this is my common. (See Coils.jpg)
Next was to determine the sequence ... this was just by trial an error but here it is...
+ - + -
4 3 4 3
1 4 2 4
4 2 4 1
3 4 3 4
4 1 4 2
2 4 1 4
... Note the polarity. So A proposed driver circuit might be composed of 4 Half-Bridges (See HD Drive.jpg)
Here is a circuit that will spin up the hard drive to a high speed.
I just thought I would pass this information along (I hadn't seen Hard drive motors being re-purposed here in the forum)
The motors are 6 Phase 24 Steps per revolution or 15 Deg per step.
IC Layout Engineer
Post Edited (Beau Schwabe (Parallax)) : 2/14/2010 2:43:56 PM GMT