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Hard Disk Motor

Discussion in 'Electronic Basics' started by Jack// ani, Sep 25, 2005.

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  1. Jack// ani

    Jack// ani Guest

    Hi there,

    I took out spindle motor from a junk seagate hard disk. Now I'm
    wondering how to drive it, having 3 pins this one is very similar to RC
    servo motor. Any help....

  2. Andrew Holme

    Andrew Holme Guest

    Try Googling for "Brushless DC" with and without "back-emf sensing" and/or

    Basically, you drive it with a 3-phase version of the H-bridge (i.e. 6
    switching transistors). "Six stepping" is how you get it started, until
    there's enough momentum to sense the position from the back-emf. You need a
    micro-controller with A/D inputs. I recently knocked-up the basic
    six-stepping controller with a pot to control the speed. It stalls if you
    crank up the frequency too quickly.
  3. Jack// ani

    Jack// ani Guest

    Hi Andrew,

    Thanks for reply.....can you please show me your schematic or suggest
    some link. How to figure out the pins....

    Thanks again
  4. Andrew Holme

    Andrew Holme Guest

    Try this

    See figure 3 and table 4.

    I didn't draw a schematic for my circuit because it was so simple. I
    used a TTL shift register and a quad schmitt NAND. One of the schmitt
    triggers was the speed control oscillator.

    Regarding pins, if it doesn't work, pick two at random and swap them.
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