Magnet Myths and Misconceptions

[SeaMonkey]

Knowns, unknowns, and beyond.

[TinselKoala]

Hey Dave

Ever seen these mono polar motors with the disk mag magnetized to the AA battery and the wire loop that spins around it?  Well this should be similar except im not using 1 wire as they are, but have a rotor with the say N poles of multiple mags very close to the inside windings of a toroid coil. Like Faraday, with current flowing in all the wires the same direction, the rotor should spin with DC applied to the coil.

The other way of doing it would be to have say 2 copper rings, a top and bottom with many thin wires attached from the bottom ring to the top ring, probably as many as possible so there is no spacing between thin wires, then apply dc or pulsing to the top and bottom rings so all the thin wires conduct current in the same direction. This should make the rotor move, all mags with same pole outward.  The first one like I said was simple rough slap together, nowhere near perfect. But the rotor would pop into acceleration just tapping the coil ends with voltage.  I dont know why it would go in either direction at times. could have been spacing of the toroid windings. Inside the say air core toroid, when dc current is applied, the field is oriented in one direction internally, and on the outside of the windings the field is oriented in the opposite direction. So using the toroid model may pose issues as to how it affects the facing field of the magnets once current is applied, due to the field of the mag is inside an outside of the toroid winding before current is applied. But my 2 rings with thin wires vertical from the bottom and top ring eliminates some of the toroidal core area concentration. 

Im planning the build at my shop as we speak. Going with the top and bottom ring with thin wires. Thought of just a short copper tube, 2in is what I have, but I believe there would be too much eddy currents vs thin vertical wires in parallel.      Plus, in the tube,  if we attach input wires to the top and bottom of the copper tube, would currents be equal and in the same straight up or down direction in all portions of the tube. 

hope to complete today.

Mags

If I am understanding your description properly, I made a device something like that back in 2000 sometime. It was the first AC homopolar generator I encountered. Not super efficient but if you spun it you could clearly see the alternating current it generated.

In your reversible one, are you sure you weren't seeing the Marinov Ball Bearing Motor effect in your bearings and shafts, instead of the homopolar dynamo effect in the disc?

[TinselKoala]

This is not good TK-can you not get it all shiped down to you?. Would be awsome to see all your old gear up and running again.

Yes, it is not good. Please check your PMs!

[Magluvin]

If I am understanding your description properly, I made a device something like that back in 2000 sometime. It was the first AC homopolar generator I encountered. Not super efficient but if you spun it you could clearly see the alternating current it generated.

In your reversible one, are you sure you weren't seeing the Marinov Ball Bearing Motor effect in your bearings and shafts, instead of the homopolar dynamo effect in the disc?

Hey T

While looking through all my stuff(good junk ) to build the dual ring, thin wire design, I found the toroid coil and rotor I messed with back then.  The toroid is wound on a pvc board ring, about 4in in dia 1/2in thick and 1/2in deep I wound it tight with 26awg 1 layer all the way around.  The rotor was not as good as I have shown in previous projects, a lil off center. Rotor has 4 1/4in x 1/8in neo disks. Im going to fix that setup to see more what was happening and show.

So the mags of the rotor are all N out, or south, but all the same. Ill have to check if N, but I usually tend to favor N in these cases just to do so. The rotor is mounted inside the toroid so mags are all facing the inside of the coil as it spins.  I imagined that the rotor would spin when dc was applied to the coil. But sometimes the rotor would just jerk into motion, one direction or the other when the source dc was first applied. but no constant spin. I got sidetracked soon and went to another seemingly more important project. 

So all this talk here reminded me of it. So Im putting it back on the table.  The 2 copper rings with thin wires soldered from the top ring to the bottom would be to simulate the inner side of the toroid windings without the complete wraparound of the toroid, so all the wires from top ring to bottom ring have current in the same direction, down or up.  In order for it to be a dc gen, I would say that mags would have to be all the way around the rotor as to affect all the vertical wires equally, or close to equally, otherwise the wires not induced by the mags would dissipate the currents generated output due to all wires in parallel connected to the top and bottom rings.

Sort of if instead of 1 loop of wire from top to bottom of a AA battery with a magnet stuck to the bottom of the battery, we encompass the whole battery/mag combo with many wires. Also, instead of the magnet at the bottom(or top) of the AA battery as we have seen many times, we get the magnet(rotor mags) close to the surface of the spinning wire(my case spinning rotor), instead of working the magnet at a distance as shown in these simple 1 wire loop motors.

Hope that makes sense till I get it together. Working on it tomorrow.

Mags

[TinselKoala]

@Mags... ok, I see. Yes, it makes sense. And I have a new little homopolar motor that I'll be showing in a little while myself, nothing new but perhaps a little different than what is normally shown.

Here's something for you to try: But you have to use a saturable-cored toroid for this. Instead of having the rotor and toroid in the same plane, mount the axle of the rotor along a diameter of the toroid, so that they are at right angles. Then you will have the rotor magnets "cogging" at the closest approach to the toroid... and then if you pulse the toroid, it will saturate the core and reduce the rotor magnet attraction for as long as the pulse is on. You can turn this effect into a motor drive. It's the basis of the Steorn Orbo, actually, what I call a CEPM, core effect pulse motor, a very interesting critter, it operates not on repulsion or attraction, but by reducing attraction as the magnet moves away from the "cogging" position.
Good luck, I will be very interested in what you come up with. I'd love to follow along on my own but I can't maintain the necessary tolerances with my present restricted toolkit.