@gravityblock

The current/voltage polarity reverses if the facing field reverses (north/south) and it also reverses if the direction of facing rotation reverses.  So if you look at the other side of a spinning unipolar generator, both the direction of rotation reverses and the polarity of field reverses so the voltage/current polarity from the axis to the rim remains the same.
  As for the external circuit, it has no effect on the voltage or the back emf.  This may seem contrary to textbook theory or logic, but remember the field does not rotate in space (like the image from an optical lens) so there is no coupling between the external wires/circuit and the field except for perhaps some movement of the lead wires when current flows through them due to the presence of the large primary field.  That movement will not noticeably affect the rotating generator. 
  There are 3 factors that dictate back emf; brush design, current load and current saturation.   LL losses can not be avoided unless (first) a brush collects current evenly around the perimeter.  Second, the higher the load the more evenly the current is distributed; leading to current saturation of the disc and ultimately to possible reduction/elimination of LL losses.  Current levels may have to reach 10's of thousands of amperes in a solid rotor before LL losses are reduced.  My solution is to radially segment the disc then put the segments in series through coupling to another segmented disc.  This forces a relatively uniform current distribution and amplifies the output voltage by many factors.  The amplified output voltage is then much more practical and the needed current load for current saturation is reduced by many factors.

-BWS

Quote from: BWS on May 25, 2009, 05:37:50 PM
@gravityblock

The current/voltage polarity reverses if the facing field reverses (north/south) and it also reverses if the direction of facing rotation reverses.  So if you look at the other side of a spinning unipolar generator, both the direction of rotation reverses and the polarity of field reverses so the voltage/current polarity from the axis to the rim remains the same.
  As for the external circuit, it has no effect on the voltage or the back emf.  This may seem contrary to textbook theory or logic, but remember the field does not rotate in space (like the image from an optical lens) so there is no coupling between the external wires/circuit and the field except for perhaps some movement of the lead wires when current flows through them due to the presence of the large primary field.  That movement will not noticeably affect the rotating generator. 
  There are 3 factors that dictate back emf; brush design, current load and current saturation.   LL losses can not be avoided unless (first) a brush collects current evenly around the perimeter.  Second, the higher the load the more evenly the current is distributed; leading to current saturation of the disc and ultimately to possible reduction/elimination of LL losses.  Current levels may have to reach 10\\\\\\\'s of thousands of amperes in a solid rotor before LL losses are reduced.  My solution is to radially segment the disc then put the segments in series through coupling to another segmented disc.  This forces a relatively uniform current distribution and amplifies the output voltage by many factors.  The amplified output voltage is then much more practical and the needed current load for current saturation is reduced by many factors.

-BWS

After more thought, you are right about the direction or polarity of the current being the same on both sides of the magnet, but I have a solution to this.

Take two magnets and put there South Poles together to form a larger magnet that would then have the North Poles on the outside. With this setup the current will have a different polarity on each side of the magnet.  You could even put your segmented disks on each side that would rotate with the magnet.  Instead of using tape to hold the magnets together, you could use a thin carbon sheet between the magnets (I read somewhere how to do this without tape and if my memory serves me correctly it was a carbon sheet).

This would be a much simpler way than having 2 counter rotating disks on separate shafts.  Also the disks would already be coupled together to have the same effect you are referring to without all the trouble you are going through in order to accomplish this.

I understand your reasoning for having brushes that are 360 degrees around the disc.  I am not concerned with this part at the moment, although I realize the importance of this.


Cheers,

GB

Edit:  You may not even need the segmented disks or the tapered rollers in this setup due to the fact that it would already be coupled together.

[quote author=gravityblock
Take two magnets and put there South Poles together to form a larger magnet that would then have the North Poles on the outside. With this setup the current will have a different polarity on each side of the magnet.
GB
[/quote]

@gravityblock,
  Well, there are 2 serious problems with your idea:
  First, 2 opposing magnets (especially neo 52's) will have a terrific opposing force.  You'd have to use something more like hardened bolts (not tape) to hold them together.  The neo 33's I use (4.5" dia) would have a repulsive force of about 800 lbs.
  Second, when you oppose 2 magnetic fields you effectively cancel the net field, so if you put an inductive disk between the 2 opposing fields, it would have no induction in it during rotation due to there being no net field.  I learned all about this aspect of field cancellation and all about the inability to shield against the field in the rotating frame of unipolar generators (using mu metal)  in my 1995 US patent which is also available at www.magvortechs.tk.   That machine was constructed at 18" diameter and had 4000 1/2" dia neo 32's with 2000 in one direction and 2000 in the other; it failed miserably.
-BWS

Quote from: BWS on May 26, 2009, 07:24:22 AM
@gravityblock,
  Well, there are 2 serious problems with your idea:
  First, 2 opposing magnets (especially neo 52's) will have a terrific opposing force.  You'd have to use something more like hardened bolts (not tape) to hold them together.  The neo 33's I use (4.5" dia) would have a repulsive force of about 800 lbs.
  Second, when you oppose 2 magnetic fields you effectively cancel the net field, so if you put an inductive disk between the 2 opposing fields, it would have no induction in it during rotation due to there being no net field.  I learned all about this aspect of field cancellation and all about the inability to shield against the field in the rotating frame of unipolar generators (using mu metal)  in my 1995 US patent which is also available at www.magvortechs.tk.   That machine was constructed at 18" diameter and had 4000 1/2" dia neo 32's with 2000 in one direction and 2000 in the other; it failed miserably.
-BWS

This is funny.  Of course you can't use tape to hold your magnets together (maybe my magnets, but not yours).  That is why I suggested the carbon sheet.  Also, there is a trick on how to bring those two opposing magnets together with very little effort.  Maybe take a look at Butch LaFonte's threads to see how to do this.

I don't think you are correct about the carbon sheet canceling the fields.  I have already done this without the fields being canceled or weakened with mu metal.  Oh, and don't forget about a Halbach Array being able to accomplish this also.

The carbon sheet is used to hold the two magnets together without tape and would not be used as a conducting disk that would otherwise be on the faces of the magnets. 

If your magnets have a conductive coating, then you wouldn't need the disks.  If your magnets have a conductive coating and you need the disk to be segmented, then you could place a segmented disk on each side of the magnet that would rotate with the magnet.

You are not understanding me at all!   Grrrrrrrrrrrrrr

@gravityblock,

I apologize if I upset you, I had no such intentions.
My only intention here is to help to realize a successful machine which circumvents all or some of LL losses, and unfortunately my experience only seems to aggravate you.
  Here's the thing; there is no such thing as a magnetic monopole.  You can try all you want but the magnetic field needs a return path just like a circuit.  In my 1995 patent I use a steel plate to attract the 2 opposing fields (did you notice that?)  It really doesn't matter how you get the 2 opposing magnets together, you will reduce the field strength on the outer surfaces considerably, thus reducing voltage, and there is a bigger problem when you try to electrically connect the 2 circumferences of the discs; (this is harder to explain, so take your frustrations out on me if you need to)  when you put the fields together you produce a very strong radial magnetic field.  This radial magnetic field must then be crossed by your electrical connection around the perimeters of the 2 discs.  This now makes a drum shaped unipolar generator that will generate a counter productive voltage.  This can not be avoided or shielded.  I have this device and can show the productive voltage and the counter productive voltage on such a machine in the attached photo.  That machine has 2 opposing fields held together by a steel plate in the middle.  The inductive disks on either side are connected around the perimeter with pins that were shielded from the strong radial magnetic field (unavoidably produced by the opposing fields) by mu metal rated at 20 times the field there.  The shields completely failed to negate any of the counter productive voltage there.
  But don't take my word for it, spend your own $100,000.00 and find out for yourself.

-BWS