PS / Current Limiting Resistor Question

[jessbussert]

Hi Folks,

I just bought four old Superior Electric Slo-Syn unipolar steppers for next to nothing. I already have a Delagrange 4-axis board that is rated up to 10A (http://www.dtllc.com/files/4XCNC10Brev1.pdf) , and I have a simple power supply that outputs 26VDC at 2A. The steppers themselves are two each of the following:

ss250-200 / bm101010, 200 step, 225 oz/inch, 2.5VDC, 5A, 5ohm
m092-fd-322 / bm101025, 200 step, 200 oz/inch, 3VDC, 4A, 5ohm

My questions are:

1) Can I drop a current limiting resistor in series with the steppers and drive it with my existing driver?
2) If so, what value and rating of resistor?
3) Am I gonna fry anything?

I think best practice would have me buy a chopper driver. Unfortunately I'm broke and I already have this particular driver that I'd like to make use of.

Any help would be greatly appreciated.

Thanks,
Jessica

[NC Cams]

MOst if not all your questions can be answered via Bob Campbell's website wherein he explains hot to build a stepper P/S.

[jessbussert]

Thanks for the link. I'm new to this stuff and I'm nervous of toasting the driver, the steppers, or myself.

I don't need someone to do the work for me, but I'd sure appreciate it if someone could offer an "answer key" so I can confirm that I'm understanding things correctly. Plus, it would be nice to understand the reasons -why- things work the way they do.

For example, in Campbell's write-up, it says that the minimum voltage for the steppers is 20x their rating, and the maximum is 25x. I've heard this a number of times before but it still confuses the heck out of me. Why do the manufacturers rate the motors so low if that's not how they are used? Also, I've heard 20x, 25x, 30x, 40x, and more. Is there a tested value that is the best? Is it different for different motors? What are the pros and cons of the different values? How would a noob like me know what is the -right- answer?

I'm happy to post any more ratings or measurements for my motors if that would help, but I'd sure appreciate it if someone would care to mentor me through this first PS build.

Thanks!
Jessica

BTW: The PS that I built earlier started smoking... Ugh! It still meters out as expected, but I unpluged it quickly and haven't a clue what I did wrong!
-J