Homopolar Generators - Unanswered Questions and Design Details

[BinaryMan]

Yeah you're right the voltage is the same but a thicker disk will act like a heavy guage wire in cases where a higher current is desired.

Now, something that's confusing to me is why the voltage is undetermined if the disk and the external circuit are both rotating. Does this mean that it cannot power a load?
(examine: http://en.wikipedia.org/wiki/Homopolar_generator)

In the picture for instance, if the device is on and rotating, will the light bulb be powered by the circuit if (1) the bulb and connection wiring are attached and rotating as well or (2) if they are not rotating but just attached to the rotating parts with brushes etc?

In the second picture, there's an example of using conductive belts between devices to transfer current. The disk acts like a battery, so multiple devices with the right magnetic field orientations can act like batteries in series. If the load is electrolysis, having rotating parts should still work in the liquid which would have an advantage. The trick in most designs is transfering the current efficiently between the rotating and non-rotating parts. This design still doesn't feed the current back into the electromagnets or motor though.

* Found out that water's resistivity is so high that the voltage of a typical generator probably won't do much good.

[mr_bojangles]

very good points

i have one homopolar generator that wouldnt work as a motor

http://www.overunity.com/index.php?topic=7130.msg166911#msg166911

magnets are indirectly exposed to coils inducing current


let me know what you think


until next time

[the_sealab_2021]

How do i calculate the generated output of a single disk rotor i made on an engine lathe while attending college. Regarding copper rotor size, this one i made is 4 inches in diameter and only .90 thick.

Can i calculate the energy output related to the size before i design a commutator frame for the rotor?

Friction is a issue so i plan to make my generator look like an hard drive, I thought of several ideas to save my butt inventing but the rotor is known for destroying the commutator if it’s output too strong per revolution it spins at..

Can anyone help me calculate how fast i should spin this rotor before I even build a frame for it?

[Yucca]

Now, something that's confusing to me is why the voltage is undetermined if the disk and the external circuit are both rotating. Does this mean that it cannot power a load?
(examine: http://en.wikipedia.org/wiki/Homopolar_generator)

In the picture for instance, if the device is on and rotating, will the light bulb be powered by the circuit if (1) the bulb and connection wiring are attached and rotating as well or (2) if they are not rotating but just attached to the rotating parts with brushes etc?

Your case (1) will not light. Your case (2) will light:

I tried the experiment of spinning The magnet disk along with the takeoff and load. Took me a few tries and a few flying capacitors to get it balanced well enough. I just stuck the cap to the axle using super glue.

Magnet: N52 Nickel Coated Neo (diam=38mm thick=6.5mm)
Electrolytic cap: 6.3V 1000uF
Resistor: 100k metal film

Outer rim is connected to the -v cap terminal.
The magnet axle is connected via the resistor to the +v cap terminal.

In this configuration the cap will discharge at about 2mV per second.

I discharged the cap by shorting and then did a spin up to 3000RPM for 2 minutes.

I noticed no difference in the capacitors charge after measuring as soon as it stopped. spinning, GUTTED!

I wondered if the centrifugal force made my rim connection go open circuit as it's only bound on with tight sellotape so I also tried precharging the cap to 300mV and then left it to discharge for 30 seconds. Tried this spinning and static, same discharge rate.

The same mag produces over 50mV using brushes at that speed.

[Groundloop]

Yucca,

I think the biggest problem with a HPG is the high current and low voltage output. If we manage to make a HPG that do the opposite then all problems solved. The reason for the high current and low voltage is the metal disk very low resistance. No high voltage can or will develop in such a disk. My proposal is to use a disk made out of a material that gives us a high resistance from the center of the disc to the edge. Do you think it is a viable approach?

Groundloop.