Hard Disk Motor

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.

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

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.