mixing DC power supplies

[perfectbite]

I do not have a 17VDC power supply but I do have individual 5VDC and 12VDC power supplies each with a different but above 2Amp rating and I need 17 volts for a stepper motor test. My humble question to you all is 'Can I series the different power supply outputs to get 17VDC without smoking either power supply?' Thanks.

[Dave Dixon]

Probably - - BUT - - First you need to be sure that both power supply returns (-) are isolated. Have them each plugged in and turned on and check for continuity between the two power supply returns. If there is no continuity - you are in business. Most good power supplies have the return (-) isolated from case/line ground, but not all.
Good luck,
Dave

[Dave Dixon]

On another note, how about two nine volt batteries = 18V. If you have to have 17 use a diode or two as discussed in the thread "Voltage drop across silicon diode"
Dave

[perfectbite]

Thank you Dave, that worked. I did think of using 9V batts but my original problem (the one I wanted to check) may have been a lack of amperage to begin with, it wasn't. Stepper notors may be strong but I found, much to my disappointment, that if the load doesn't move on the first pulse it ain't gonna move on the umpteenth pulse (it wasn't much of a load either and steppers aren't gravity friendly, even very light vertical loads tend to fall back down). Meanwhile, back at the drawing board, one door closes another opens.

[Chris Smith]

Dont forget that its only as strong [amperage] as the lowest number out put value of any multiple PS. Same goes for batteries, its only as strong [amperage]as the weakest battery.