I am wanting to make a simple and easy speed/direction controller for a hdd spindle motor i have aquired. the motor is a 3 wire. Any ideas on a curcuit that would work. Would be nice if I could controll the speed with a POT and switch the directin with just a simple switch. Any help would be much appreciated.

 

The hard drive that you took the motor from will have a controller IC in it. Use the number on it to search Google for the data sheet. HDD motors are not very powerful, almost no torque but very high speed. Not useful for anything but a HDD.

 

I don't have the ic it came out of, just the motor.

 

I don't have the ic it came out of, just the motor.

Then just Google for HDD motor controller IC.

 

I found the original IC circuit for the spindle motor, but how do I use it?

 

I found the original IC circuit for the spindle motor, but how do I use it?

We're not going to be much help unless you can at least come up with the part number of the IC.

Then you need to find the datasheet for the IC.

 

Most brushless DC motors used in disc drives have a number of windings. These windings need to be switched in a specific sequence in order to get the motor to spin. The controller IC does that, and unless you take the motor apart and understand the magnetics and the sensors for rotor position then you have relatively little chance of being able to duplicate the algorithm. Accelerating the motor from a dead stop is a different algorithm than keeping the platter spinning at say 7200 RPM ± 1RPM

I don't think a pot will do you much good at all -- sorry.

 

I have two IC circuit boards, one for a star(4 lead) wound motor and one for a Y(3 lead) wound. I have a bunch of numbers for both. Which one would be easier to operate, star or Y? If it does not matter which numbers would you need? I have a bunch of numbers on the cover of the hard drive.

 

They're both about the same. What about the sensors?

 

Where would they be located at? I think the motors are sensorless.

 

Possible but unlikely IMHO. In order to spin up the platter you need to know where the poles of the rotor are located so you can apply maximum torque in the forward direction. There is a high probability of a head crash if you rotate the platter backwards or apply the brakes instead of moving forward.

We used Hall Effect sensors and located them underneath the magnetic poles on the rotor. For a 4-pole motor we had eight stator windings on a PC board also mounted underneath the rotor.

 

The motor does not come apart, so I can not tell what kind of sensors they are. Where the motor hooks on the the IC board there are three chips that say motorA, motorB, motorC. My guess is those are the chips that fire the pulses to A,B and C phases. I guess I do not know where to go from here.