Brushless controllers and hall effect sensors


I've got a load of assorted brushless motors kicking around, pulled from old hard drives, video recorders etc. and I've noticed that they often have what appears to be a controller IC on the same board as the motor. However, I've looked up the part numbers, and looked around on the internet, and I can't seem to find anything out about them. Is it possible to use them for anything? I know that they're unlikely to have much torque, but they'd still be useful if they were usable. If not, How hard is it to make a basic brushless speed controller? from what I can gather, they put out three sine waves to the coils, each presumably a third of a cycle out of phase, but most people seem to reckon they're a pretty tricky thing to get working, so...?

One of them's in an old VCR head, and I was thinking of using it for a computer input for scrolling through stuff, or MIDI controll in a way similar to a monome arc. If I can get the motor going, I was contemplating using it to provide a bit of haptic feedback, but if not, I was wondering if it's possible to use the existing ring magnet on the motor casing with one or more hall effect sensors to provide the position sensing. How would I go about this? I'm guessing that you'd arrange about three of them around the circumference, but I don't know. Also, would this still work if the motor was used, or would the magnetic field from the coils mess that up?

Thanks in advance.

Thanks for the reply.Seeing

Thanks for the reply.

Seeing as I’ll want pretty precice position control, I presume that I’d be best using analogue output hall effect sensors, and setting the switching point on the microcontroller. I can’t see any sensoring on the existing controller board, so it’s presumably sensorless, and I guess won’t be good enough at low speeds for what I want. I’ll still try and get it working, though. Would an arduino-based controller have enough processing power to handle the low-speed motor control, USB comms and possibly a bank of LEDs, or would I need more than 1 microcontroller?

Hackaday has recently had a couple brushless motor driver


Just doing a search via google with: brushless motor

will turn up hits. 

Thanks for the links.

Thanks for the links. looking at them again, I think I might have seen and forgotten about these a bit back, so thanks for putting them up.