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how to use hard disk spindle motors

Discussion in 'Robotics & Mechatronics' started by mrmmani22, Mar 7, 2006.

  1. Frankco

    Frankco New Member

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    Wow Burt this is great I'll have to try it.
    Thanks a lot for posting the circuit.
    Frank
     
  2. DrIguana

    DrIguana New Member

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    Hi guys,

    Just though I would add my 2 cents worth. I've also played with these motors a bit. The motors I've seen also have their coils in a Y configuration with a tap in the middle. I use a different driver but otherwise my approach is very similar to that of be80be.

    The problem I found is that the timing is critical. When I used fixed delays the rotation is not very robust. Sometimes it would spin up, other times not. Sometimes it would spin for a while and then lose sync and stutter to a stop.

    When used in a hard drive, the magnetic information on the drive platters is used to synchronize the coil timing to the rotation. Coil transitions occur at just the right moment and the motor accelerates strongly and holds speed against all perturbations.

    I made a simple optical encoder disc using a laser printer and a transparency. I used an optical interrupt switch to sense the black to transparent transitions and used this to clock the coil transition. The change was dramatic. With this feedback I could easily reach the rated speed of the motor. After slowing the platter with a finger, the motor would rapidly recover its speed.

    A friend of mine, Paul Rowntree, adapted this approach for use with the propeller chip and posted the project at

    Propeller Object Exchange

    Hope this is helpful.

    DrIguana
     
  3. HATHA

    HATHA New Member

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    if the HD motors are BLDC then doesn't it have some hall effect sonsors, is it possible to sens the rottar via such hall effect sensors
     
  4. dave

    Dave New Member

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  5. Frankco

    Frankco New Member

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    Hi Hatha,

    You probably know this but, the position of the spindle is "written" on the platter of hard drives. All that is gone with the removal of the platter and the read head. In the link DrIguana provided they replaced the position information with a transparent disk mounted to the spindle and a sensor for feedback.

    There are chips out there that will use back EMF sensing for sensing the position of the spindle motor.

    Would this chip work for that?
    "Connections for TPIC43T01 and Discrete Power NMOS FETs"
    http://www.electro-tech-online.com/custompdfs/2009/07/slit117.pdf
     
  6. HATHA

    HATHA New Member

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    Hi Frankco

    thank your for your interesting article yes this chip (TPIC43T01) has the ability to sens the rottar position via hall effect sensors. have to read more about this
    thank you again
     
  7. malekblbl

    malekblbl New Member

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    the brushless motor with 4 wires means that its star winded, with 3 wires means delta winded, to controle it try the TDA5140A...
    see this image [​IMG]
     
  8. Frankco

    Frankco New Member

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    Thanks malekblbl,

    Do you know of a good source for the TDA5140A? The source I found runs about $16 ea. with shipping included.

    Frank
     
  9. malekblbl

    malekblbl New Member

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  10. Frankco

    Frankco New Member

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    Thanks malekblbl! You made my day.

    I have a lot of hard drives that I want to turn into compact small orbital shaker tables. I need to be able to control the speed from 0 to about 45rpm. I'm not sure if this chip will do it or even the hard drives but I'll give it a try. Oh, the tables are needed for plant cell suspensions. I am growing individual plant cells trying to cross them with unrelated plants. Kind of making a new plant that hasn't existed before. Weird I know. I'm a science geek. I have some vids on YouTube that are a few years old. I'm trying more advanced things now. YouTube - fbt2007's Channel

    Thanks again,
    Frank
     
    Last edited: Feb 2, 2010
  11. malekblbl

    malekblbl New Member

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    you can control the speed of the motor using this ic with controling the voltage of Vmot and its simple....
    but i want to know if i can control 2 identical brushless motors with the same speed using a single ic or two cascaded ic's
     
  12. karusel

    karusel New Member

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    Hello :)

    I've been searching the web for a while, but I found most information I need in this thread it mostly just cancelled the ideas I've had and raised additional questions.

    I have a small project going - I would like to use 3 15K Cheetas as gyroscopes. I understand now, the by far easiest way to do that would be by keeping them as they are and simply putting the power to the connector pins. Trouble with that is that the drives are incredibly heavy (over 1.5lbs) and that would be pretty much useless for me. If I strip them down, the read/write head must go too, so do I assume correctly the speed information fed to PCB will be lost and the drive will not spin normally? Ideally, I would strip the drive down to the spindle motor and platters, period. If there is no other way, I'd have to keep original PCB's, but there's less problem with that, than keeping that load of dead weight.

    Unfortunately I'm not an expert in electronics - a nice portion of this thread is like french to me, is there a simple way to make the drive spin at a constant speed without the R/W head?
     
  13. Hero999

    Hero999 Banned

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    It seems like an expensive solution unless you got some second hand broken drives for cheap.

    What about just buying some cheap high speed DC motors and mounting metal discs to them? You could use a heavier metal such as steel so it doesn't need to run as fast or the rotor can be smaller.
     
  14. karusel

    karusel New Member

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    Yes the price was reasonable... the problem with doing stuff like that from the scratch is that it would be very difficult to kill vibrations, which is one of the reasons for building a gyro in the first place. HDD's spindles/platters are absolutely perfectly balanced or - way better than I could balance them.
     
  15. Hero999

    Hero999 Banned

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  16. ashonic

    ashonic New Member

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    Hi frnds
    I've got n seagate spindle motor ( 3 pins ) .....
    when i supply current, it just jerks and stops .......
    wat 2 do...
     
  17. alec_t

    alec_t Well-Known Member Most Helpful Member

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    You have just responded to a 5 year old thread! Better to start your own.
    Did you read the answers in the thread?
    BTW, welcome to ETO.
     

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