Can anyone please give me some info on the subject of
an extremely simple drive circuit for a stepper motor?

What we have is a simple old hard disk stepper motor,
without a drive circuit. (Yes, it was ripped from an old pc quite
roughly )
Instead of powering it off a low voltage DC source,
we want to feed it AC grid power, in our case 230V 60Hz.

Just about everyone we have asked says things that come down
to simply using a transformer and rectifier bridge to turn the
AC into lower voltage DC and use that to power the stepper motor,
using a normal hard disk driver circuit.
And obviously that can be done, but can we not somehow utilise
the 60Hz AC more directly, instead of first transforming it into
DC and then pumping it through a DC driver circuit to get the necessary
phase difference?
Can we somehow make use of that, and at the same time make our
drive circuit a little simpler?

In other words: what is the simplest effective circuit to make a
hard disk DC stepper motor run on 230V 60Hz AC?

Your help is greatly appreciated!

Hi Koen,
I'd say a simplest circuit to drive a stepper motor is still the one suggested - suitable DC supply and a special stepper controller chip.
Can you provide any data of your stepper? Like Phase nominal voltage/resistance/current, full/half step options, the number of phases (are there 4 (bipolar) or 6 or more (unipolar) connecting wires), etc.

If volume is not a problem, you can use a PC switcher power supply, having +5V, +12V,..
I've used Motorola's chip MC3479 in the past, and it worked fine...

Some links:

http://www.doc.ic.ac.uk/~ih/doc/stepper/control2/connect.html

http://www.aaroncake.net/Circuits/stepper.asp

http://www.tigoe.net/pcomp/code/category/code/arduinowiring/51

Cheers!

Thanks Spinner!

I don't have it here right now but I think it's a 4 phase motor that needs about 5V,
think it's full step but must check that and the rest.

Yeah, just using a transformer and a controller chip would probably be easiest...

Thanks for the info!

Float a ground.