[cor bit]

I'm working on refurbishing a CNC milling machine, and while the mechanical part seems pretty straightforward to me I don't have much electronics experience.

After some research I decided to buy the Probotix ProboStep unipolar stepper driver, because it seemed to be the cheapest thing that would do what I wanted. The product description claims that it will take voltages up to 44V, and I understand that higher voltages are generally better. I have the old power supply that came with the machine, and for some reason it has a 20V rail, -20V rail and ground. Can I hook the -20V rail to "ground" on the board, and effectively have a 40V power supply, or would that not work?

I hope there's someone out there who understands this better than I do, because I'm in a bit over my head with these circuits.

Thanks,
Kyle

[Jeff Shepard]

Yes, that is what +20 and -20 mean. If you put a voltage meter up to the leads...the red prob(+) to the +20 and the black prob(-) to the -20 you will get 40 volts....if you put the black prob to ground you only get 20 volts. That is how I am getting 24 volts from my old computer power supply.


Wow...I just looked at the original date of this first post....my bad for digging up an old post....dang...and I knew the answer too.