Free Energy | searching for free energy and discussing free energy

Mechanical free energy devices => mechanic => Topic started by: tao on March 20, 2007, 04:02:23 PM

Title: Zen Generator - A No Back Torque Electromagnetic Generator
Post by: tao on March 20, 2007, 04:02:23 PM
(moved over from this thread: http://www.overunity.com/index.php/topic,2093.msg26072.html#msg26072 )

Ok guys... Heres the deal.

I was going to keep all my research and work quiet, until an unspecified time. But I feel this TYPE of generator almost speaks for itself, so there isn't really much HIDING or SECRETS that can be kept with it, lol.

So, without further adou, here is the KEY mechanism to this design.

Now the world knows, if it didn't already!

I made this image MANY months ago, just so you know.

It should be self explainable.................................

I have named it: The 'Zen Generator,' due to it's circular shape, the same type of shape that is popular is the Zen arts...

Enjoy...
Title: Re: Zen Generator - A No Back Torque Electromagnetic Generator
Post by: FredWalter on March 20, 2007, 05:57:41 PM
(moved over from this thread: http://www.overunity.com/index.php/topic,2093.msg26072.html#msg26072 )
here is the KEY mechanism to this design

Have you built any prototypes?

If so, can you post some pictures? What sort of results have you gotten: power in, to turn the magnet, versus power out, from the coil?
Title: Re: Zen Generator - A No Back Torque Electromagnetic Generator
Post by: dingbat on March 20, 2007, 06:52:44 PM
I think what will happen is the flux from the magnet will not split evenly when the coil is conducting - like the Flynn effect.  Some of the flux will be coerced or repelled by the coil, throwing the system out of balance.  It is an interesting concept though.  Are you going to build one to find out?

db
Title: Re: Zen Generator - A No Back Torque Electromagnetic Generator
Post by: AhuraMazda on March 20, 2007, 10:14:04 PM
Have a second look at how the winding is shown on the toroid. Why do you think they are not perpendicular?

AM
Title: Re: Zen Generator - A No Back Torque Electromagnetic Generator
Post by: bitRAKE on March 21, 2007, 02:51:37 AM
those yoke coils from a TV don't have a round cross section, but might be a quick way to test the effect. I'm still playing with the ones I have here - looks like I might have to rewind the coils. I'm using some little rare earth magnets and a 3V motor from the scrap bin.
Title: Re: Zen Generator - A No Back Torque Electromagnetic Generator
Post by: Dansway on March 21, 2007, 05:45:16 AM
@AhuraMazda

Hmm......

How about they are slanted to create a "slanted bias" in the magnetic flux of the toroid.

Dan
Title: Re: Zen Generator - A No Back Torque Electromagnetic Generator
Post by: bitRAKE on March 21, 2007, 06:35:18 AM
Wire wrapped on a cylinder is slanted as well - the artist's intent is not clear. Could the slant be the required slant to wrap a layer of wire?
Title: Re: Zen Generator - A No Back Torque Electromagnetic Generator
Post by: Paul-R on March 21, 2007, 04:03:32 PM
A rather different idea, but maybe you should see this
motor by Stefan Marinov. Figure 1, page 3.
www.monstein.de/paraphysics/Marinovmotor/v05n3wes.pdf
It might add something useful to the debate.
Paul.
Title: Re: Zen Generator - A No Back Torque Electromagnetic Generator
Post by: hartiberlin on March 21, 2007, 04:50:13 PM
Hi Tao,
this is nothing new.
Steven Sullivan has got a patent for it and he reported about 1500 Watts
output versus about 1200 Watts input already a few years ago,
when he was still reachable via email.
He posted also a picture of his setup,
if I remember correctly.

Unforntunatly he never came back and reported any further progress.

Search for his company Omnidyne or something like this..

Maybe it went Black projects ?

It was one of the best anti-Lentz law designs so far.

Regards, Stefan.
Title: Re: Zen Generator - A No Back Torque Electromagnetic Generator
Post by: tao on March 21, 2007, 04:59:54 PM
I know this is nothing new, see my posts in the other thread.

I am not claiming anything new. I am merely showing people the complete principle in a new thread, with very logical reasonings and a nice image ;).
Title: Re: Zen Generator - A No Back Torque Electromagnetic Generator
Post by: konduct on March 22, 2007, 12:58:29 PM
Looks nice Tao.  Keep up the good info.  We all could use a little more Zen!
Title: Re: Zen Generator - A No Back Torque Electromagnetic Generator
Post by: Low-Q on March 22, 2007, 10:45:47 PM
Wouldn't this generator provide more current and less voltage when loaded? The permeability of the iron will decrease if the coil is loaded, the magnetic field will follow the part of the toroid with no coil when the coil is sort cut, hence the missing back torque. At the same time no energy is generated in the coil. Hmmm... I think we again are walking on a dead end (or blind alley if you like).

Vidar
Title: Re: Zen Generator - A No Back Torque Electromagnetic Generator
Post by: tao on March 23, 2007, 02:23:40 AM
The ONLY way that the permeability of the iron will decrease is IF the coil is outputing energy!

So, you can't have one without the other.

The only way the flux from the magnet will move is IF there is energy being output on the coil. A changed permeability is a direct result of output current in the coil, period, there is no other way that the flux is going to distort like that.

So, there is either energy being output on the coil OR the flux in the toroid IS NOT distorting, period...


Wouldn't this generator provide more current and less voltage when loaded? The permeability of the iron will decrease if the coil is loaded, the magnetic field will follow the part of the toroid with no coil when the coil is sort cut, hence the missing back torque. At the same time no energy is generated in the coil. Hmmm... I think we again are walking on a dead end (or blind alley if you like).

Vidar
Title: Re: Zen Generator - A No Back Torque Electromagnetic Generator
Post by: bitRAKE on March 23, 2007, 04:08:32 AM
Yeah, saturation seems to be the limiting factor. Would a powerful slow magnet be better than a fast weak magnet? Should the coil cover half the toroid or less?
Title: Re: Zen Generator - A No Back Torque Electromagnetic Generator
Post by: tao on March 23, 2007, 05:13:14 AM
As of right now, I feel the coil should cover up to an arc of 0-60 degrees...


Yeah, saturation seems to be the limiting factor. Would a powerful slow magnet be better than a fast weak magnet? Should the coil cover half the toroid or less?
Title: Re: Zen Generator - A No Back Torque Electromagnetic Generator
Post by: Low-Q on March 23, 2007, 12:50:24 PM
The ONLY way that the permeability of the iron will decrease is IF the coil is outputing energy!

So, you can't have one without the other.

The only way the flux from the magnet will move is IF there is energy being output on the coil. A changed permeability is a direct result of output current in the coil, period, there is no other way that the flux is going to distort like that.

So, there is either energy being output on the coil OR the flux in the toroid IS NOT distorting, period...


Wouldn't this generator provide more current and less voltage when loaded? The permeability of the iron will decrease if the coil is loaded, the magnetic field will follow the part of the toroid with no coil when the coil is sort cut, hence the missing back torque. At the same time no energy is generated in the coil. Hmmm... I think we again are walking on a dead end (or blind alley if you like).

Vidar

Lets assume there is a voltage output - AC I guess when the magnet rotates. This voltage should be possible to use to something. If so, current will flow through the coil wire. When current flows through the coil wire, it will induce an opposite magnetic field in the iron core in the area where the coil is placed. This magnetic field will force the magnetic field from the magnet to take another path - the second and only alternative: The other side of the toroid where there is no coil. And to alter the magnetic path, as long ther is a path to use, does not require energy - hence no back torque. (I'm thinking loud now - I'm not an expert in this)

Therefor Lenz law is then still topical, but it all happens in a manner that does not influence the torque in the rotating magnet. Lenz law will still have an effect on the output, and limit the output when the coil is loaded.

I can read that there is for example 10amps used to run the motor (To rotate the magnet), and 20 amps can be measured from the generator. At which voltage is these currents measured?
The question is then; How many watts do you put in, and how many watts do you get out, as watt is a product of volt and amp?re.

Br.

Vidar
Title: Re: Zen Generator - A No Back Torque Electromagnetic Generator
Post by: tao on March 23, 2007, 03:09:08 PM
Well, Steven's patent states a 12V@0.8Amp input and a 6V@40Amp output.......
That is 9.6Watts in, 240Watts out....

His other device was 140Watts in 1200Watts out, as put forth by Stefan Hartmann.

So, we either believe or not, either way, it needs to be built for true realization...

Everything points to the fact that the Zen Gen DOES work... I wouldn't have brought it up otherwise.
Title: Re: Zen Generator - A No Back Torque Electromagnetic Generator
Post by: Low-Q on March 23, 2007, 04:15:25 PM
Well, Steven's patent states a 12V@0.8Amp input and a 6V@40Amp output.......
That is 9.6Watts in, 240Watts out....

His other device was 140Watts in 1200Watts out, as put forth by Stefan Hartmann.

So, we either believe or not, either way, it needs to be built for true realization...

Everything points to the fact that the Zen Gen DOES work... I wouldn't have brought it up otherwise.

OK, I missed that information, sorry.

Next question:

Is the output 1200 watts peak, continous or average?

I have the tools to build a test generator, and this weekend my wife is going to visit my parents-in-law - her parents so to speak. And I'm left alone, with plenty of time :) I can't say for sure that I'll be finished this weekend. We'll see.

Br.

Vidar
Title: Re: Zen Generator - A No Back Torque Electromagnetic Generator
Post by: Nali2001 on March 23, 2007, 05:59:08 PM
don't forget, for that 240 watts out he used a like 12kw core. The 'amount' of core material is important. Like posted before from Steven he recommends using core's from 2.5hp motor...

You should use a slotless motor of 2.5 hp or larger as the smaller cores have an inductance that is very high and the terminal voltage will drop as you load it.

This IS important and I know most people think it's not.
I have seen like 3 replication of these systems but their put out nearly nothing. Because their build far too small.
Title: Re: Zen Generator - A No Back Torque Electromagnetic Generator
Post by: Nali2001 on March 23, 2007, 07:13:08 PM
although not quite a 12kw core, this one is a good starting size probably.
Title: Re: Zen Generator - A No Back Torque Electromagnetic Generator
Post by: Low-Q on March 23, 2007, 07:23:35 PM
don't forget, for that 240 watts out he used a like 12kw core. The 'amount' of core material is important. Like posted before from Steven he recommends using core's from 2.5hp motor...

You should use a slotless motor of 2.5 hp or larger as the smaller cores have an inductance that is very high and the terminal voltage will drop as you load it.

This IS important and I know most people think it's not.
I have seen like 3 replication of these systems but their put out nearly nothing. Because their build far too small.
My experience shows that the inductance increase as the iron mass increase, not the opposite.

Vidar
Title: Re: Zen Generator - A No Back Torque Electromagnetic Generator
Post by: gyulasun on March 24, 2007, 06:01:24 AM
don't forget, for that 240 watts out he used a like 12kw core. The 'amount' of core material is important. Like posted before from Steven he recommends using core's from 2.5hp motor...

You should use a slotless motor of 2.5 hp or larger as the smaller cores have an inductance that is very high and the terminal voltage will drop as you load it.

This IS important and I know most people think it's not.
I have seen like 3 replication of these systems but their put out nearly nothing. Because their build far too small.
My experience shows that the inductance increase as the iron mass increase, not the opposite.

Vidar

Hi Folks,

You should use a slotless motor of 2.5 hp or larger as the smaller cores have an inductance that is very high and the terminal voltage will drop as you load it.

I think Sullivan meant that slotless motors of under 2.5 HP have smaller core cross sections, hence they need more number of turns (this gives the needed inductance for the smaller cores) and the copper loss (DC resistance) this way also increases, hence the output (terminal) voltage tends to drop in a higher extent (when you try to use them in his patent's setup)  when loaded than motors with bigger cores (i.e. over 2-3 HP).

So you are both correct: using cores of higher cross section will involve higher self inductance with a certain number of turns and this is needed for inducing more voltage while keeping the copper loss at a reasonable level. Also, saturation levels usually are  more favorable towards higher cross sectional cores, so magnet strength can be increased.  So the bigger core size you have, the better.

Regards
Gyula
Title: Re: Zen Generator - A No Back Torque Electromagnetic Generator
Post by: Low-Q on March 24, 2007, 08:32:02 AM
OK,
 I will try to make a generator with a much smaller toroid, just to see the principle. It should be possible as a smaller generator, in spite of relatively greater loss, should be able to produce energy.
Hopefully the generator output will be in proportion to the energy requirements of the smaller DC-motor which drives the rotating magnet.

Br.

Vidar
Title: Re: Zen Generator - A No Back Torque Electromagnetic Generator
Post by: eavogels on March 30, 2007, 12:11:00 PM
Hi.
Now this is perhaps a stupid question but is the toroid supposed to be a ring magnet?
Thanks.
Eric.
Title: Re: Zen Generator - A No Back Torque Electromagnetic Generator
Post by: Low-Q on March 30, 2007, 01:29:27 PM
Hi.
Now this is perhaps a stupid question but is the toroid supposed to be a ring magnet?
Thanks.
Eric.
The toroid is a ring of laminated unmagnitized iron plates, as in a regular toroid transformer, but without all the wire. A short coil i winded on just a small part of the toroid. This coil are not intended to be used as an electro magnet, or ring magnet.
The toroid is not a magnet itself, but a rotating magnet inside (Where N and S is pointing in each oposite direction) is spinning to generate electricity in the coil - a generator which we believe voilates Lenz law when loaded. Some of us desagree.

Br.

Vidar
Title: Re: Zen Generator - A No Back Torque Electromagnetic Generator
Post by: eavogels on March 30, 2007, 02:33:16 PM
Thanks Vidar.
I found this device interesting since it was rather easy to test. Just collecting parts now. I have loads of ring magnets but I have more problems finding a big enough laminated iron ring.
Regards,
Eric.
Title: Re: Zen Generator - A No Back Torque Electromagnetic Generator
Post by: Low-Q on March 30, 2007, 02:46:46 PM
I believe you probably can use a ring magnet. As the magnetic field is static, an 90o on the induced field from the spinning permanent magnet, I believe you can get the same or similar effect. I really don't know, but it's worth a try. You could also demagnetize the ring magnet as well, so you don't have to worry about over saturation of the ferrite material in these magnets.

Br.

Vidar
Title: Re: Zen Generator - A No Back Torque Electromagnetic Generator
Post by: eavogels on March 30, 2007, 09:27:53 PM
Half an hour in the oven at max. temperature will kill the magnet and just leaves a ferro ring.
I'll try, thanks.

Eric.
Title: Re: Zen Generator - A No Back Torque Electromagnetic Generator
Post by: Paul-R on March 31, 2007, 04:02:42 PM
I have always felt that a magnetic motor based based on
de-magnetising and re-magnetising in the opposite
polarity "on  the fly" might provide OU. It would be a slow
running machine.

Presumably the electrical cost of doing this would rule it out.
Paul.
Title: Re: Zen Generator - A No Back Torque Electromagnetic Generator
Post by: Low-Q on April 02, 2007, 10:08:22 PM
Now, I have done some simple tests just to see the potential in a Zen-generator. I winded approx 30 turns on a small toroid, and used my drill to run the magnet. Unloaded I achieved 0.7 Volt. Not much, but the rpm was not high and the amount or turns in the winding are not high.
The resistance in the winding is approx 0.2 Ohm, capable of providing half of the voltage measured when loading the winding with 0.2 ohm. In other words approx 0.61 Watt at max load.
Well I loaded the winding with 3.3 Ohms. Guess what! The voltage did drop from 0.7 Volt to 0.3 Volt. If I do some simple calculations, in respect to the resistance of the winding, the total impedance of the generator increased from 0.2 Ohm to approx 4 Ohm - maybe due to "flux escaping" in the toroid when the winding was loaded.
Approx 0.7 Volt in 3.3 Ohms, is approx 0.15 Watt. This "flux escaping" reduced the energy potential from 0.15 Watt, down to 0.022 Watt. A energy loss of 85% with an easy load.

What does this mean?
A Zen-generator will probably never be able to run itself.
A Zen-generator does not voilate Lenz law, as the back torque is probably internal in the toroid itself.

PS! All values are average effective values. Peak values may be very different.

Br.

Vidar
Title: Re: Zen Generator - A No Back Torque Electromagnetic Generator
Post by: hartiberlin on April 02, 2007, 11:13:43 PM
Hi Vidar,
many thanks for your test.
Please supply your whole calculations, so it is getter clearer.
Many thanks.

P.S: These devices always rely on very specific materials,
so it realy depends heavy on the used magnets and toroids
and coils and magnet flux paths..
The slightes modification can have totally different output results,
so a quick setup with the wrong type materials will not result
in a success...

Regards, Stefan.
Title: Re: Zen Generator - A No Back Torque Electromagnetic Generator
Post by: Low-Q on April 03, 2007, 09:01:07 AM
Well, there is actually no spesific calculations others than the resistance of the wire, but the tests have being done this way:

Equipment:
Small toroid. Outer diameter:7mm, Inner diameter:50mm, hight:30mm
Two 5mmx5mmx50mm neodym magnets polarized across the length
Drill
Plastic insulated wire

The building:
The wire is used to make the coil which is a double layer @ 25mm length. Approx 30 turns.
The magnets are fasten directly on the steel chuck.

Now, the drill is running while I'm closing the distance between the toroid and the spinning magnets. If I get too close, the iron in the toroid will be saturated - which is not what I want.

A Fluke AC-volt meter is used to measure the coil while the magnets are spinning.

Regarding the calculations done when the coil was loaded, I measured first the voltage with a known resistive load. The calculation concluded that the flux density around the coil was reduced when the coil was loaded. As the voltage did drop much more than the wire resistance should promise, when the coil was loaded, the flux density must then increase on the other half of the toroid. This will in turn virtually make a higher impedance in the generator, as the fact is that less flux is running through the coil when it's loaded - hence the dramatic voltage drop. I will apply pictures when I get home, but here is a drawing of the setup.
Title: Re: Zen Generator - A No Back Torque Electromagnetic Generator
Post by: Nali2001 on April 03, 2007, 07:25:29 PM
Maybe
You should use a slotless motor of 2.5 hp or larger as the smaller cores have an inductance that is very high and the terminal voltage will drop as you load it.
Title: Re: Zen Generator - A No Back Torque Electromagnetic Generator
Post by: Low-Q on April 04, 2007, 12:15:21 PM
Maybe a 2kW toroid should do... $150 - 200 I guess ::)
Title: Re: Zen Generator - A No Back Torque Electromagnetic Generator
Post by: Nali2001 on April 04, 2007, 05:18:18 PM
Hey! don't tell me you don't know that all this f.e experimentation does come at a price. But if you are ghetto like me. You build the stuff you need. Takes longer I know but it's cheap. Here is how I made that core. It is build from a burned out 15orso kw motor. I cut the core in half, and removed the fingers from the laminates then re-insulated the laminates and put the thing back together. And viola a big ass ring core is born. And it did not cost more than like $10 - And I only used half the original core.

 
Title: Re: Zen Generator - A No Back Torque Electromagnetic Generator
Post by: Low-Q on April 04, 2007, 10:24:20 PM
That was heavy... Could you maybe make a few turns of wire to that toroid, and spin a magnet inside to see what happens when the coil is loaded?

Br.

Vidar
Title: Re: Zen Generator - A No Back Torque Electromagnetic Generator
Post by: hartiberlin on April 05, 2007, 02:09:06 AM


Regarding the calculations done when the coil was loaded, I measured first the voltage with a known resistive load. The calculation concluded that the flux density around the coil was reduced when the coil was loaded. As the voltage did drop much more than the wire resistance should promise, when the coil was loaded, the flux density must then increase on the other half of the toroid. This will in turn virtually make a higher impedance in the generator, as the fact is that less flux is running through the coil when it's loaded - hence the dramatic voltage drop. I will apply pictures when I get home, but here is a drawing of the setup.

Hi Low-Q,
nice setup,
but maybe the voltage dropped much more, cause you did not put the
magnet rotor directly into the toroid and thus too much
airgap was present !
This airgap can then press out the magnet flux into other directions,
so it would be good, if you could try again by putting the magnets directly into the
toroid hole and see what happens then, when you load the coil.
Many thanks in advance.

What material does your toroid have ?
Is it pure iron or laminated iron bands stacked ?
Does it have much eddy currents ?

Regards, Stefan.

P.S: Also it could be good to place an iron core between the2 rotating magnets,
so the flux is concentrated to the toroid side at each magnet end, so the flux
inside the 2 magnets does not have such a big airgap...
Title: Re: Zen Generator - A No Back Torque Electromagnetic Generator
Post by: FredWalter on April 05, 2007, 04:11:20 PM
Here is how I made that core. It is build from a burned out 15orso kw motor. I cut the core in half, and removed the fingers from the laminates then re-insulated the laminates and put the thing back together.

How did you remove the fingers from the laminates?
Title: Re: Zen Generator - A No Back Torque Electromagnetic Generator
Post by: tao on April 05, 2007, 04:53:45 PM
Yes, you need to use one continuous magnet, and it need to be IN the hole area of the core, EXACTLY like it is pictured in my first post on this thread.




Regarding the calculations done when the coil was loaded, I measured first the voltage with a known resistive load. The calculation concluded that the flux density around the coil was reduced when the coil was loaded. As the voltage did drop much more than the wire resistance should promise, when the coil was loaded, the flux density must then increase on the other half of the toroid. This will in turn virtually make a higher impedance in the generator, as the fact is that less flux is running through the coil when it's loaded - hence the dramatic voltage drop. I will apply pictures when I get home, but here is a drawing of the setup.

Hi Low-Q,
nice setup,
but maybe the voltage dropped much more, cause you did not put the
magnet rotor directly into the toroid and thus too much
airgap was present !
This airgap can then press out the magnet flux into other directions,
so it would be good, if you could try again by putting the magnets directly into the
toroid hole and see what happens then, when you load the coil.
Many thanks in advance.

What material does your toroid have ?
Is it pure iron or laminated iron bands stacked ?
Does it have much eddy currents ?

Regards, Stefan.

P.S: Also it could be good to place an iron core between the2 rotating magnets,
so the flux is concentrated to the toroid side at each magnet end, so the flux
inside the 2 magnets does not have such a big airgap...
Title: Re: Zen Generator - A No Back Torque Electromagnetic Generator
Post by: Nali2001 on April 05, 2007, 06:53:36 PM
Well I have a lathe and a milling machine so I can do anything with metal.

Here is how I made that core. It is build from a burned out 15orso kw motor. I cut the core in half, and removed the fingers from the laminates then re-insulated the laminates and put the thing back together.

How did you remove the fingers from the laminates?
Title: Re: Zen Generator - A No Back Torque Electromagnetic Generator
Post by: tru168 on April 18, 2007, 03:43:48 PM
Hi,

  The voltage drop from 0.7 volts to 0.3 volts when loaded, I think you will need to wind another similar coil at another side.
I think the magnetic filed in the toroid run tru the shortcut when the coil connect to load, let say, your winding is place at left site of the toroid, when you turn the magnet at its center, the N and S magnetic field will go tru right site of the toroid when you load the coil. By wind another set of similar windings at right site, and series the 2 coils together, you will find that it will not drop the output voltage when loaded.

 I tried the similar ideas few years back, I used small c core with 120 turns of SWG21 magnet wire on each site and I get 1.8V at 0.59 ampere. Yes, that is with load, and when unload, I get nearly 2 volts .  I also using a drill to spin the center magnet too.

(Sorry for my poor explaination, I seldom speak english! )

  Just my 2 cents! :)

Regards,
EW

Title: Re: Zen Generator - A No Back Torque Electromagnetic Generator
Post by: gyulasun on April 18, 2007, 05:58:26 PM
Hi EW,

Thanks for the very interesting info you gave, this is good news!

Can you remember if you checked the current draw of your drill : did it increase much when you loaded the output coils (1.8V/0.59A) ? Maybe you still have got the setup?

I think it would be good to look for the smallest power electric motor used in RC toys just enough to rotate the center magnet, this way keep the input power need at the minimum possible.

Thanks again,

Gyula
Title: Re: Zen Generator - A No Back Torque Electromagnetic Generator
Post by: tru168 on April 18, 2007, 06:25:12 PM
Hi Gyula,


  I didn't measure the current of the drill, as what you say, I should use smaller motor to test it out.
  I can feel that the RPM of the spin motor will be the same, with or without load.Thats means the load will not increase the current of the drill so much .
  I stop the experiment for quite a long time, thinking that it might not work.

   I still keep those c core ( rated 64 watts and spec sheet says saturation at 1.6T, M5 grade silicon steel) and some spare copper wires. The inductance of the 120 turns per side seems lower than I would like to continue the experiment, thats why I can only get less than 2 volts. Bigger cores and more turns will solved the problem.
 I will try again to build proper one and see how it goes.

 Normal RC model motor might not give you good efficiency, for example, Speed 540 type RC plane motor will never exceed 50% of efficiency. I will suggest to use RC type brushless motor which will have high torque and can directly drive the center magnet, and its efficientcy will reach 90++% its a bit expensive , and need to build a speed controller for the motor but I think it worth to invest a good motor for above mentioned project..Need to plot out the current draw VS spinner magnet weight and get the most efficient working point first,then only go for next step, that is, the output coil.
    The mentioned setup loves high RPM, the higher the RPM, the higher the efficiency. I will not allow the setup to run anything lower than 3500 RPM or efficiency will drop greatly. Again, just my humble opinion.......


Regards,
EW