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hard drive spindle motor? Answered

I have a hard drive spindle motor that i have taken off of my old 10 gb Hard drive. I was wondering if i would be able to run this motor off of a pc molex connector. i have extended the wire from the molex plug and touched them to the leads on the motor, but all it does is jerk. I can't get it to stay spinning. Do you have to have a controller mechanism of some sort or what? I have tried the red wire and ground and the yellow wire and ground. They both don't seem to work. Would make a difference if i solder the wire onto the motor? I was just thinking this would make a great fan or something along that order.


do you have any more info on this? I'd love to give it a try. THANKS

Haven't done much with this for quite a while. I know how a 3ph. motor works so I wanted to see if I could create a discrete component circuit that would work just for the heck of it. BTW, discrete stuff is a dying art as a hobby so finding it is difficult. I robbed old power supplies and other peripheral parts for it, cross checking with data sheets available on the net.
Build the tri-flop first, grounding the emitters to verify sequencing. (BTW, just add more stages if you want multiphase sequencing.) The motor circuit runs hot so heat sinks are in order. Possibly different rated switches and/or biasing could adjust current, voltage or timing and make it more efficient.
Others here have mentioned timer and inverter IC's would work if you wanted to go that far. RC 3 ph supplies are available for such things as model helicopters if you want to take a chance. Expensive.
I connected 4 motors and got them all running up. Additional motors don't need the center tap as the primary one sets the sequence. They will 'cog' if you start at high speed, so set the pot low and bring it up slowly.
Let me know if you have any luck and/or make improvements.

Hi, Several replies mention "COG".

Could you define that?


Brushless motors have magnets that are attached to the part that spins, and coils wound on the part that doesn't. Cogging is when the magnets and the coils attract or repel each other in a way that makes the motor act jerky or spin with a 'bumpy' feeling. If the motor and driver are working properly, the motor should spin smoothly in only one direction. Cogging occurs most often when the driver gets ahead of the motor, hence the fact that you should let it run up slowly. Nowadays you can get BLDC motor controllers from hobby stores, etc. for pretty cheap. For a HDD motor, you probably only need one that's designed for 5-10 amps. I've seen those on eBay for about $8-10, but you also need what's called a servo tester to act as a stand-in for an RC transmitter and receiver. Those are also a few bucks on eBay. Good luck and happy modding!

(PS, I found a great use for old HDDS, put more platters on them in place of the spacers after taking the heads out and use them as gyroscopes.)

I've developed circuitry for driving precisely this sort of motor. You can see it on my website: http://wingzero.ath.cx/index.php?page=hard-drive-motor

Check under the heading Projects: Hard Drive Motor and other pages under that.

Hope it helps!

Atmel has a howto on spindle controllers here

The generally accepted definition of a BLDC (BrushLess DC) motor is a permanent magnet motor with trapezoidal back-EMF, as opposed to the sinusoidal back-EMF found in permanent-
magnet synchronous motor. This note applies to BLDC motors with
trapezoidal back-EMF.

In every commutation step, one phase winding is connected to positive supply voltage, one phase winding is connected to negative supply voltage and one phase is floating. The back-EMF in the floating phase will result in a ìzero crossingî when it crosses the average of the positive and negative supply voltage.

The zero crossing occurs right in the middle of two commutations. At constant speed,
or slowly varying speed, the time period from one commutation to zero-crossing and
the time period from zero-crossing to the next commutation are equal. This is used as
basis for this implementation of sensorless commutation control.


9 years ago

I know this is an old topic, but for anyone landing on this now... The easiest way to power the spindle motor is with the original control. Wire the motor onto the HDD board as it was normally connected. Next, connect the board to a computer power supply. The motor will spin up. If the power is not connected to a motherboard, just cross any black wire on the motherboard power connector with any black wire on the connector. This will bypass the security feature on the power supply.

I am almost sure it is a spindle motor. It is the motor that spins the platters. What would i need to power it?

Nah, it's a 3 phase brushless motor. A stepper is similar, but not quite. a stepper has many "notches" per rotation. you cycle through them a step at a time by sequentially driving contacts. A 3 phase brushless is similar in that you drive it with sequential signals, but it only has 3 "notches" per rotation, and it's intended that you not drive them until they "cog", but instead switch off power to one phase, and onto the next while it's still coasting forward. Stepper motors used to be used to control the heads in very old hard drives, mostly pre-ide drives under 40MB or so. They're also used in floppy drives. So, what you would actually need is a brushless DC motor controller.

hard drive spindle motors are peculiar, because they're three phase stepper motors. generally, if you take an ohmmeter to the pins, one pin will connect to the other three at a specific ohmmage, and then trying to measure the resistance between any two of those three will result in about twice as many ohms. the one that connects to all three at a low ohm rating is the ground, the other three are your phase 1, 2, and 3. this could probably be made using ttl logic gates and a 555 timer with relative ease.

Nice! Thanks a lot Chuck6! I was looking for a way to power my spindle motor. I will definitely try this.

ya that is helpful Chuck if i knew how to read that pdf. I was planning on doing this a while ago, but thanks for the heads up.


10 years ago

Saw hmms query about spindle motors and got me thinking so I dug out some parts from my junk and built this. The first circuit is based on the common flip-flop (a tri-flop?) and an inverter circuit. It spins the motor up and even has some speed control. It will drive several motors in parallel. Just new here, so let me know if you got it all.......


10 years ago

i just opened an old scsi hdd. i too am toying with the idea to put the spindle motor to some good use but the spindle ic of the hdd has burnt :(. so if anybody knows any simple driver circuit for the spindle motor pls post!! BTW i'm planning to use 12v 1amp power source.

Try this. Take the wires you extended and plug them back into the hard drive control board. disconnect everything else from the board except the power plug. drive should try to spin up, and I think it will continue to run at it's idle speed. The spindle motor is a "stepper" type motor, and requires a control circuit to operate. Let us know if it works.

Ya that does work. I did that right away. But it was spinning way to fast for my liking. I want to mount a fan on the motor, but 7200 rpm is way to fast. I might just buy some DC motors and use them instead. If anyone has any suggestions for some DC motors that spin from 1000 up 5000 RPM that would be appreciated. Could i just use a fan controller for a regular DC motor?

The platters must turn at a very precise speed so that the heads can read the data. Hence the stepper motor.


11 years ago

Most spindle motors seem to be "brushless"" three-phase motors rather than actual stepper motors. Driving them is very similar to driving a stepper motor, but you usually have an extra coil to drive, speeds are much higher than typical steppers, there's a third coil to drive, and the coils are frequently driven with analog waveform (equivalent to "micro-stepping" on a stepper) rather than digital "steps." (in a drive, this is all done by a special purpose driver chip that generates three sine-waves (or digital approximations thereof) 120 degrees out of phase with each other.) The "brushless motors" used by some model aircraft and RC cars/boats/etc are VERY similar to spindle motors. In fact, there's a whole industry out there "rebuilding" spindle motors into higher-power versions for modelers. This means that you can buy a brushless motor speed controller and use it to drive a spindle motor. (however, these start at about $10...) It OUGHT to be possible to drive such a motor like a stepper at low speeds and low power, but I haven't seen much information on how to do so...


11 years ago

Hard drive spindle motors are stepper motors, the heads are moved by a coil interacting with those strong "rare earth" magnets. You need a stepper motor controller circuit to spin the motor.