I hope this is being posted to the appropriate area (search yielded similar topic).

First off, thank you for the post on the homopolar motor. Amazingly fascinating for as raw and simple as it is. A problem has cropped up in my experimentation of the device and I can't seem to find a reason for it (I've asked around and done my own research). I'm trying to remove the battery from the equation (wait for it ) and replace it with an external DC power source. I've got an older HP power variable power supply that I am using as the replacement, which, in my mind, should be an acceptable substitute to the battery. Well, nothing happens except for a spark here and there. I'd think that the same principles would apply, regardless of the source of power. I like to think that I have a pretty good base understanding of electricity and physics, but I'm definitely not an expert. Any ideas on how one would introduce an external power source to this configuration? Is it possible or does the battery play another role other than just a source of DC power in the demonstrated configuration?

Thanks!

On a more detailed look and further experimentation, it appears that I've grossly underestimated the current potential of an AA battery . The power supply I'm using has a maximum of 500ma output (up to 30V). After reducing and refining the friction point a bit more, it does appear that I am getting very, very minimal rotation from my external PSU, so it must be something related to the current output limit. Sorry for the bother and I'll keep messing with it.

Thanks!