Does the size of the opening in the center of a coil matter?

[rukiddingme]

Does the size of the opening in a coil affect the output? Can I make a coil with no gap in the center and will it be the same as one with a larger opening?

I want to try to make a coil to use on the device at www.koremag.com. It's the big output coil that wraps around the outside of the rotating magnets. Can someone give me a guess on what size or gauge wire I should use for this coil?

How far into a coil will a 2000 gauss magnet penetrate? Meaning, if i have a magnet moving along the coil, how far does the field have to penetrate into the coil for best output? Does it have to reach the other side, or just the middle? Will a 2000 gauss magnet penetrate into a coil enough to make it work? I'm guessing there will be at least an eight of an inch between the coils and the magnets.

Anyone know what the permeability of Hy Mu 80 is? Anyone know where I can buy a couple of feet of Hy Mu 80?

Thanks

[capthook]

Are they air coils? (should be to reduce cogging/drag)
And you should have numerous individual coils rather than 1 big loop.
I would recommend something like a 3-phase axial flux design like Hugh Piggot's - modified to your design.
http://www.scoraigwind.com/
and download a free .pdf of an older design:
http://www.scoraigwind.com/pmgbooklet/index.htm

And an excellent site with much discussion on the axial flux:
http://www.fieldlines.com/

And the magnets on either side of the coils should be placed in attraction to pull the flux through the coil rather than reducing it by repelling.

And the coil holes should be the same size, shape of the magnets.

"How far into a coil will a 2000 gauss magnet penetrate?"
Do the paperclip test.  Put a small paperclip on a flat, smooth surface.  Hold a ruler vertical next to it.  Lower your magnet to the paper clip until it just starts to lift.  Note the distance between the two.  That is your answer.

[rukiddingme]

Are they air coils? (should be to reduce cogging/drag)

The output coils are air core.

And you should have numerous individual coils rather than 1 big loop.

Five sections made of a coil each. Does that sound about right?

I would recommend something like a 3-phase axial flux design like Hugh Piggot's - modified to your design.
http://www.scoraigwind.com/
and download a free .pdf of an older design:
http://www.scoraigwind.com/pmgbooklet/index.htm

Yes, on page 8, that's what I imagined the coils would look like. Thinner and longer. But I still don't know if I can make the center Minimum. Can I eliminate the center opening and not affect its performance?



Thanks


Anyone have a guess on what size wire I should use for this coil?

Does the size of the center opening affect the output of the coil?

[tropes]

Anyone have a guess on what size wire I should use for this coil?

Does the size of the center opening affect the output of the coil?"

Hi RUKidd
It's been a while.
With the opposed piston motor I found the best (highest R.P.M.) with a core 1/2 the diameter of the magnet and the outer diameter of the coil the same diameter as the magnet (1.5 inch magnet -  1.5 inch coil). The core made of mild steel pipe was better than a solid core.
As far as wire size, I used 26 AWG with 18V, 3/4" coil and 22 guage wire with 36V, 1.5 inch coil. Core diameter was 1/2 coil diameter.
Hope this helps.
Tropes

[rukiddingme]

Hey Tropes,

I saw your video, what a beautiful motor you have. Great work!

Thanks for the info, every piece of information helps.

Hope all's well with you.

Thanks for the response.