Brushless controllers and hall effect sensors

Community General Discussions
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Hi

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.

2

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?

3

Hackaday has recently had a couple brushless motor driver

articles.

http://hackaday.com/2013/09/21/building-a-brushless-motor-controller-around-an-atmega-chip/

http://hackaday.com/2012/09/04/open-source-brushless-motor-controller/

Just doing a search via google with:

site:hackaday.com brushless motor

will turn up hits. 

4

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.