Hard Disk Motor

[Jack// ani]

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....

Thanks

 

[Andrew Holme]

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....

Thanks

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

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.

 

[Jack// ani]

Hi Andrew,

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

Thanks again

 

[Andrew Holme]

Hi Andrew,

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

Thanks again

Try this http://www.embedded.com/story/OEG20010304S0010

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.