Homopolar Generators (N-Machine) by Bruce de Palma

[tim123]

@all
http://arxiv.org/ftp/physics/papers/0012/0012009.pdf
Hypercom

I've been reading this thread from the beginning, and I'm amazed by the high-quality of info that has been posted...

This article by Hypercom is stunning and profound... It'll take a while for it to sink in though.

He posted more good info in this thread:
http://www.overunity.com/9706/homopolar-stack-multiple-generators-on-one-common-shaft-brent-hasty/

I am guessing that this lack of torque reaction with the field magnet is what you mean by nothing to push against, but the return current path provides plenty to push against the current in it sets up a magnetic field opposite to the current flowing though the rotor. That 27000 rpm 140 lb rotor mentioned in my other post didn't come to a stop by itself.

PulsedPower clearly has lots of real experience, and his posts are excellent too...

I'll finish reading, and see where it goes...

[tim123]

Here's an updated version of the axial HPG design - including some new things i've learned from reading the thread...

1) The magnet doesn't have to move at all.
2) The current is generated because the rotor is moving relative to the brushes (& hence the rest of the circuit).
3) A log-spiral shape conductor is optimum for maximum efficiency.
4) There's every reason to expect a back-torque, as conventional HPGs do.
5) And if it's somehow avoided - that may mean no voltage, but who knows...

So in this version
- the conductor is an axial log-spiral. It could, in fact be many individual wires I guess, not just one...
- the central brush is *the* place where back-torque will manifest
- the central section could be made very thin to reduce that torque...
- the solenoid could be a PM tube, though it would need a hole for the central brush too.

[tim123]

It occurred to me that it might be possible to do it like this too:

[tim123]

Tim, does the center magnet rotate with the copper tube?   If so, is velocity differential between the two fields present, and would that negatively affect the excitation of electrons in the tube, thus limiting current output?

From what I've read - it seems not - as long as the rotor & external circuit are in motion...

In my tube design, the center mag assembly floated on bearings, held in place by the attracting field outside,  whilst the tube spun in the flux sandwich.   This requires stainless and ceramic bearings, and an insulator between axle ends, from which current from each pole is extracted.

I never got beyond building the drum end retaining parts, but I still think the design is worth pursuing.   As for your drawings, they bear much resemblance to my design.

I'm encouraged to hear you had similar ideas...

The article Hypercom posted seemed to suggest that a magnet wasn't even necessary - and the log spiral coil would generate power when rotated - all by itself - fascinating stuff...

Regards, Tim

[keithturtle]

The copper I am working with is 22 gauge, or about  0.030" thick.  It's all I could afford

OK, then I just came up with about 6 square feet of some 0.062" copper sheet.   I hope to fashion some 11 inch disks to spin in some ferrite magnet fields.  Nothing fancy, just something I hope to create some kind of point of reference with.

I have a PWM controlled DC motor capable of about 1/4 HP at around 3000 rpm to drive it with.   Proper pulleys will take it faster.

Maybe after 4 years I can finally get something built.

Then again, maybe not

Turtle, really slow