Drive for a 4-wire unipolar stepper

[Kelpo]

Good morning

I'm trying to get hold of a drive to control a three coil four wire unipolar (I think) stepper. I've come to understand that this isn't exactly the most common type of stepper, and therefore the search is proving kinda difficult. I'm completely useless with electronics, so building a drive myself isn't something I'd like to do, but it's not out of the question as a last resort.

The coils have a resistance of 33 ohms each, and they're arranged like this:
http://users.evtek.fi/~k0301161/Coils.bmp
That means it's unipolar, right?

The voltage used to excite the coils is 28V, so the current per phase is around 850mA

Could any of you point me to a drive that would work with this thing? I've found nothing so far.

Thanks a lot.

[James Newton]

I'm pretty sure you will need to make your own. It shouldn't be that hard... see:
http://www.forth.org/fd/Step.html Figure Two, but drop one of the transistors. Then you have to make your own control signals to move the motor by turning on and off the coils in sequence.

[jeffs555]

This page has a description of the step sequence.
http://www.cs.uiowa.edu/~jones/step/types.html

Also, are you sure it is a stepping motor? I bought some surplus motors that were listed as steppers, but turned out to be 3-phase brushless motors.

[Kelpo]

I ended up building the thingie myself, and it seems to work well enough.

It probably wasn't an optimal solution, but I ended up generating the phase sequence in Labview and amplifying it with a ULN2003 transistor array thingie.

Generating the pulses with Labview limits the motor's speed somewhat (with an older laptop I can get up to ~55Hz/phase), but I get a nice user interface with colourful buttons and smiley faces, so it all evens out.

Thanks for your help.

[harryn]

That is an interesting approach - never thought of using labview to run a stepper motor.

[Kelpo]

Heh, well. When you've got a hammer, every problem looks like a nail.

[jczarne]

Originally Posted by Kelpo I ended up building the thingie myself, and it seems to work well enough. It probably wasn't an optimal solution, but I ended up generating the phase sequence in Labview and amplifying it with a ULN2003 transistor array thingie. Generating the pulses with Labview limits the motor's speed somewhat (with an older laptop I can get up to ~55Hz/phase), but I get a nice user interface with colourful buttons and smiley faces, so it all evens out. Thanks for your help.

Kelpo,

I am relatively new to Labview...I am using a Geckodrive g203V (http://www.geckodrive.com/product.aspx?c=3&i=14460) to control a 4-wire stepper motor. I am using a NI USB-6009 DAQ with digital input from the drive. (I am building a tension stage and this motor is turning a threaded rod (1/13 pitch) on a 2:1 gear ratio)

I am confused how to get it to run with labview...how did you control you steps/pulses, speed, step rate and movement along rod, etc?
Do you have any examples that you could share. I would greatly appreciate it.

Thanks,
J