Homopolar Generators - Unanswered Questions and Design Details

[the_sealab_2021]

How fast does an unipolar rotor supposed to rotate (RPM's) in a magnetic field to generate at least the one volt its supposed to make per rotor?
What is considered too fast for a rotor that only produces one volt?

Dosent electrons flow from the center to the edge caused by centripetal and Centrifugal forces applied with a magnet field? the negative terminal is the edge of the rotor where the electrons are drawn off the rotor with a commutator right?

Please help me; I don’t want to create unnecessary study thinking that the magnet does all the work on the homopolar generator pushing electrons up to a rotor surface to be collected by a commutator..

im designing an thin commutator to slide with but i dont know if it would melt with an rotor spinning to fast powering an coil load.

i saw a note to all about OU (over unity) and disk saturation requirements, what rpm's is that achieved with an rotor this small? (4 inches in dia)

[Yucca]

Yucca,

You can easily test the theory on your existing test rotor. First make a copper ring with the same diameter as you magnet. Then solder 4 copper wires from the ring and to the center of the ring. Now you have a low resitive disk. Measure the voltage. Now replace the the 4 copper wires with resistors. Measure the voltage. More or less voltage?
...
I do not have any test setup right now. I contemplating buying some few Neo ring magnets with a diameter of 200mm and center hole of 20mm, thickness 5mm. But this will take 4 - 8 weeks to order. So for now I'm not able to test anything.

I will be grateful if you find the time to test the resistor theory on your rig.

Groundloop.

Interesting experiment, I´ll probably try that. Because my brushes are noisy. I use a scope to look at the noisy output and then I can see the max levels reached. Give me a few days but I´ll try it in the end.

If you use brushes then the heating element must be outside the rotating frame, eg. not rotating. If the heating element is rotating with the disc then there is no relative motion between the heating element and the disc, you can not extract power inside the rotating frame. You have already proven that.

In my mind I have only proven that part of the circuit must be outside of the rotating frame in order for potential to develop over the spinning disc. Do you agree that when a static brush is extracting power then that power must flow through the rotating disc. That disc has resistance so it should itself act as a heating element despite it being in the rotating frame?

It would be very handy to have a LED like device with a real low forward voltage, something to mount on the disc for doing tests like these. Even a joule thief requires 0.4v or so to light a LED, I can´t get up to that voltage with my small mag.

The 200mm ring mag sounds massive! You could probably get some decent voltage out of that. I want one!

[the_sealab_2021]

i have created an 2 sided copper PCB rotor just recently in college to experiment with, just showing to see if someone could agree that this baby could produce 2 volts each rotor.

i plan to build a frame for it soon, I'm so poor i must wait for advice to find out how fast this rotor should spin...

[Yucca]

Dosent electrons flow from the center to the edge caused by centripetal and Centrifugal forces applied with a magnet field? the negative terminal is the edge of the rotor where the electrons are drawn off the rotor with a commutator right?

Please help me; I don’t want to create unnecessary study thinking that the magnet does all the work on the homopolar generator pushing electrons up to a rotor surface to be collected by a commutator..

im designing an thin commutator to slide with but i dont know if it would melt with an rotor spinning to fast powering an coil load.

i saw a note to all about OU (over unity) and disk saturation requirements, what rpm's is that achieved with an rotor this small? (4 inches in dia)

At one point I also thought electrons were forced out by cetrifugal forces. I was wrong, you can reverse the polarity by reversing the spin or flipping the magnet.

RE saturation. I don´t think you´ll be able to saturate the thick copper disk your holding easily in a home lab environment, it looks fairly thick. But your PCB disk just might be possible?

I should point out, this saturation stuff is only hearsay to me, I haven´t tested it yet.

Anyway you should definitely get your PCB disk loaded with mags and get it spinning as fast as you dare!

[the_sealab_2021]

thanks for the info, I'm in the middle of redesigning air bearings for it since it should spin at such exaggerated rpm's.
i was wondering if i could spin it in a tank of liquid nitrogen or helium.
i wouldn't want it flying off like Frisbees so a shaft is being made.