driving a linear positioning table

Whelzorn

I have an 8 inch linear positioning table from NEAT (New England Affiliated Technologies) and have some questions on driving this thing via a BS2. Basically, this thing is just a stepper motor with a leadscrew attached to the shaft with a table that has a threaded section so that it moves along the rail as the leadscrew turns. Well I have 2 questions. Firstly, I am not 100% sure of the voltage ratings on the stepper, but I am assumimg it's 12v because it wouldn't do much more than quiver when I ran it off 9v. Is this a safe assumption? Secondly, I have the BS2 running the stepper (it's unipolar BTW) through a ULN2003. Well I have 2 problems with this. The ULN2003 is only rated for up to 500mA. The only 12v power supplies I have supply 4-6A. Thats not good, because I burnt one out (ULN2003), meaning the stepper draws more than 500mA. But I am not quite sure how much curent the stepper in the table draws, and if 500mA would be enough for it. Anyway, what would be the appropriate sized resistor to turn it down to 500mA max, and if it's not enough, what would you suggest instead of a ULN2003?

Thank you,
Justin Woodman

kelvin james

I dunno, but what you were saying about the motor " quivering ", kinda makes me suspect it is not wired properly. I have 12v steppers that run fine on as little as 3v. I took a quick look at the neat wesite and some of the docs there, and looks like the motors are in the 5-6v range and run between .8-1.5 A max. You could be sending 9v back to your driver chip if not wired properly causing the fry, but it is only a quess. The neat website has a ton of documentation on their products, maybe you should have a close look at the specs. And variable 3 to 12v wall warts work good as power supplies for steppers.
kelvin

Whelzorn

hmm... I've practically exhausted NEAT's site, where did you find the voltage info?

Justin

kelvin james

I took a couple of pages from the manuals to view. One shows the electrical specs for the type of motor you have, the other shows the wiring config. You can see, depending on the manufacturer of the motor, that the color coding can differ a lot for the common and the coils. That is why i was wondering if you had the 9v connected to a coil, it would going back to your driver.
kelvin

Whelzorn

ah, ok thank you very much.