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Author Topic: Homopolar Generators (N-Machine) by Bruce de Palma  (Read 291200 times)

mikestocks2006

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Re: Homopolar Generators (N-Machine) by Bruce de Palma
« Reply #75 on: March 30, 2008, 05:05:24 PM »
It doesn't mention anything about OU or not, but the amount of current drawn sure is impressive:

1.6 million Amps

Nature 204, 1079 (12 December 1964); doi:10.1038/2041079a0
Tests with Solid Brushes on the Canberra Homopolar Generator
R. A. MARSHALL*

Research School of Physical Sciences, Institute of Advanced Studies, Australian National University, Canberra.
*Present address: c/o Large Generator and Motor Department, General Electric Co., Schenectady, New York.

EARLY in 1963 a programme was begun with the view of establishing whether or not solid brushes could be used instead of liquid metal jets to collect the required current (1.6 million amp) from the rotors of the Canberra homopolar generator. Within the first few weeks of investigation it became clear that there were no insuperable problems. Many pilot tests were conducted and details of the design will be published later. Since then, brush gear has been designed, manufactured and installed, and large-scale tests have been made with this gear in the homopolar generator. The behaviour of these brushes has been very satisfactory.

Blamey, J. W. , Carden, P. O. , Hibbard, L. U. , Inall, E. K. , Marshall, R. A. , and Oliphant, M. , Nature, 195, 113 (1962). | ISI |
http://www.nature.com/nature/journal/v204/n4963/abs/2041079a0.html

PulsedPower

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Re: Homopolar Generators (N-Machine) by Bruce de Palma
« Reply #76 on: April 01, 2008, 01:33:33 PM »
Quote
It doesn't mention anything about OU or not, but the amount of current drawn sure is impressive:

That is their main use, high current DC, the one in Canberra had a short and bent all the buss system due to the magnetic forces between the conductors, estimated fault current 6MA,  Some newer machines make much more current but I do not know of any with a higher energy capacity, the Canberra machine is huge, it has a 2000Kw Dc generator to drive the magnet and bring it up to speed..

AbbaRue

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Re: Homopolar Generators (N-Machine) by Bruce de Palma
« Reply #77 on: April 01, 2008, 08:30:28 PM »
It would seem the best approach to building one of these would be to build a bunch of smaller units and connect them in series.
It would be very difficult finding semiconductors that could switch such high currents,
which would be needed to step up the voltage to a more useful level.
Also would be easier on the brushes to have a smaller current.

sm0ky2

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Re: Homopolar Generators (N-Machine) by Bruce de Palma
« Reply #78 on: April 02, 2008, 02:22:48 AM »
Brushless contacts, and the Return-curcuit at a Tangent, to minimize Back-EMF resultant from the drawn current.

sm0ky2

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Re: Homopolar Generators (N-Machine) by Bruce de Palma
« Reply #79 on: April 02, 2008, 02:23:35 AM »
multiple disks on a common shaft, to maximize output.


AbbaRue

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Re: Homopolar Generators (N-Machine) by Bruce de Palma
« Reply #80 on: April 02, 2008, 05:57:28 AM »
After looking at your drawing, an interesting idea just came to my mind.
Do we even need a brush to collect the power from the disks?
Couldn't you just connect a very thick conductor from the outside of one disk to the inside of the next,
all along the whole array of disks. and then just connect the end 2 conductors to the outside circuit.
If the shaft isn't a conductor the 2 ends could then be connected to graphite brushes.
Then you have a higher voltage with a controllable current level.
Perhaps the disks could be combined with metal cones placed on a shaft like this  "o-l>l>l>l>-o"
That is a simple drawing but it illustrates what I mean.
That way the outside of one disk is connected to the inside of the next one, and so on, and so on.
Plus the cone shape would minimize air friction.
From your drawings, I thought maybe this was the same principle you were thinking of.
The brushless contact and the angle of the line you drew.
I don't see any reason why this shouldn't work.
I have never read anywhere that the disks have to rub against a brush to produce electricity.
Correct me if I'm wrong on that point.



sm0ky2

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Re: Homopolar Generators (N-Machine) by Bruce de Palma
« Reply #81 on: April 02, 2008, 10:25:03 PM »
After looking at your drawing, an interesting idea just came to my mind.
Do we even need a brush to collect the power from the disks?
Couldn't you just connect a very thick conductor from the outside of one disk to the inside of the next,
all along the whole array of disks. and then just connect the end 2 conductors to the outside circuit.
If the shaft isn't a conductor the 2 ends could then be connected to graphite brushes.
Then you have a higher voltage with a controllable current level.
Perhaps the disks could be combined with metal cones placed on a shaft like this  "o-l>l>l>l>-o"
That is a simple drawing but it illustrates what I mean.
That way the outside of one disk is connected to the inside of the next one, and so on, and so on.
Plus the cone shape would minimize air friction.
From your drawings, I thought maybe this was the same principle you were thinking of.
The brushless contact and the angle of the line you drew.
I don't see any reason why this shouldn't work.
I have never read anywhere that the disks have to rub against a brush to produce electricity.
Correct me if I'm wrong on that point.




i want to stress the tangent line on a horizontal plane to the rotation of the disk.

cutting the lines back THROUGH the EMF to get to the center of the next disk, will greatly increase the back-torque on the disks.  This is the first mistake made with this kind of machine. and the moment you draw current from it, the disks will come to a HALT. and generate a good deal of heat.

having the return path at a tangent minimizes the back-torque, and with small brushless contacts there is very little friction.     

once the return-path is out of the resultant electro-magnetic field of the Disks - you can connect them in series/parallel however you like to increase your voltage or amperage accordingly.

the only way i cna see doing it like you are talking would be with sliding contacts (like a DC motor)
but this has been done before, and generates more friction than a bushless contact. as do brushes and slip-rings. - the latter two having additional back-EMF problems like described above.


mikestocks2006

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Re: Homopolar Generators (N-Machine) by Bruce de Palma
« Reply #82 on: April 12, 2008, 06:27:36 PM »
Nice demonstration, polarities change, controlled setup and metrics.
It's a variation of the original Faraday's disk but same principle.

http://www.physics.umd.edu/lecdem/services/demos/demosk2/k2-64.htm

also as it possibly ties into special relativity
http://www.physics.umd.edu/lecdem/outreach/QOTW/arch11/q218unipolar.pdf

mfred68

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Re: Homopolar Generators (N-Machine) by Bruce de Palma
« Reply #83 on: April 30, 2008, 08:13:46 PM »
Please forgive me for possibly not knowing all the technical facts about this disc idea, i havnt had much time to read it all yet, but as far as i understand the principle is to use a rotating copper disc, turning with a stationary magnet up against it (is this correct?) with the centre of the disc being connected to the metal drive shaft which is one electrical connection, and the edge of the disc being the other electrical connection via a brush.

if this is correct, what would happen if it was the disc that was fixed stationary and the magnet was put on the drive shaft instead? like that the problem of brushes would be eliminated.

would the operating principle be the same? or have i got it all totally wrong?

Gearhead

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Re: Homopolar Generators (N-Machine) by Bruce de Palma
« Reply #84 on: April 30, 2008, 09:20:44 PM »

if this is correct, what would happen if it was the disc that was fixed stationary and the magnet was put on the drive shaft instead? like that the problem of brushes would be eliminated.

would the operating principle be the same? or have i got it all totally wrong?

You have come across the anomaly of the Faraday disk.  A rotating magnet has no effect on a stationary disk while a rotating disk with a rotating or non rotating magnet will produce a potential.  The effect seems to be that the magnetic field does not rotate with the magnet.  Actually it may be that the spin of the atoms within the disk may have something to do with relativity because the outer edge of the disk is traveling at a faster rate of speed than the portions of the disk nearer the axle.

sm0ky2

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Re: Homopolar Generators (N-Machine) by Bruce de Palma
« Reply #85 on: May 01, 2008, 04:01:44 AM »

if this is correct, what would happen if it was the disc that was fixed stationary and the magnet was put on the drive shaft instead? like that the problem of brushes would be eliminated.

would the operating principle be the same? or have i got it all totally wrong?

You have come across the anomaly of the Faraday disk.  A rotating magnet has no effect on a stationary disk while a rotating disk with a rotating or non rotating magnet will produce a potential.  The effect seems to be that the magnetic field does not rotate with the magnet.  Actually it may be that the spin of the atoms within the disk may have something to do with relativity because the outer edge of the disk is traveling at a faster rate of speed than the portions of the disk nearer the axle.

its not really an anomaly,  the type of magnetic field used in these devices in a uniform, circular field. turning this field, still gives us a uniform, circular field.  So with respect to the disk, the field is not "moving".

turn the disk, and the copper moves through the field - while it does not "cut through" and perpendicular flux lines, it still causes induction within the copper of the disk.

They perform better when the magnet and disk are both moving together. (taking into consideration the additional mass that is being rotated)

mfred68

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Re: Homopolar Generators (N-Machine) by Bruce de Palma
« Reply #86 on: May 01, 2008, 02:49:24 PM »
I can get my hands on some 12" copper discs, but i only have several 1" magnets, how do i place the magnets onto the disc? do they have to be evenly spaced n,s,n,s and do the magnets have to attract each other through the disc by placing some on both sides?

or have i got it totally wrong again?

do lots of small magnets work or would i need two equal sized 12" magnets to the same size as the disc?

Also is the output ac or dc?

sm0ky2

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Re: Homopolar Generators (N-Machine) by Bruce de Palma
« Reply #87 on: May 01, 2008, 03:59:29 PM »
at a constant RPM, the output will be a high current DC.
(in most situation, load on the drive motor will increase as power is taken from the leads.)


The magnet can be a single magnet, presssed against the face (or slightly spaced) of the disk.
an alternative method i have seen uses two magnets, one below and one above:    s -disk- n (or vise versa)

with a 12" disk, the magnet should be 11 inches at least,. so that the disk is entirely inside the magnetic field.
you dont want portions of your disk extending out past the field - this causes an adverse effect and will cause extra 'drag' as well as lower the total power output of the device.

Paul-R

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Re: Homopolar Generators (N-Machine) by Bruce de Palma
« Reply #88 on: May 01, 2008, 05:05:51 PM »
I can get my hands on some 12" copper discs, but i only have several 1" magnets, how do i place the magnets onto the disc?
Can you lay your hands on a dumped video recorder which actually works? Take the lid off,
and when you see the main video head, it is, in effect, most of a homopolar generator but
without the magnets. Dismantle the recorder making sure that the head is running (you
will need to put an old tape in, set it going, and try to dismantle it whilst keeping the head
rolling.

Find out what lever is the thing which is forced back to tell the recorder that the tape is there.
Glue it fast. When the tape runs out, it should keep rolling unless there is another sensor
(which is in the tape path with a light bulb).

You will then need to get magnets as close as possible, maybe form an old micrwave oven
(inside the magnetron - a bit of a hassle). Mount them in position, and meter from the edge
of the video head to the shaft (maybe on the other side of the main board.

You should get a low vloltage but with a surprising amouunt of current.

mikestocks2006

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Re: Homopolar Generators (N-Machine) by Bruce de Palma
« Reply #89 on: May 01, 2008, 10:23:47 PM »
I can get my hands on some 12" copper discs, but i only have several 1" magnets, how do i place the magnets onto the disc? do they have to be evenly spaced n,s,n,s and do the magnets have to attract each other through the disc by placing some on both sides?

or have i got it totally wrong again?

do lots of small magnets work or would i need two equal sized 12" magnets to the same size as the disc?

Also is the output ac or dc?
Hi mfred68,
That would be a very good experiment to do.
If you have access to some basic machining, you?d need 2 wafers with holes the size of you mags and sandwich the disk between them. Poles as an example would be N-S-CopperDisc-N-S. With such a setup the expectation would be a DC out Voltage.

Also see
(http://www.stardrivedevice.com/dynamo_stator_matrix.v2.jpg)
(http://www.stardrivedevice.com/dynamo_rotor.jpg)

more complete info pics and explantions here
http://www.stardrivedevice.com/over-unity.html

I?ve attempted to contact them numerous times, as they indicated on their site that they would be posting results out soon after the build, but they have not replied.
The build had started back a a couple of years, but no results yet.

If you could replicate this and post some results either proving or disproving the design setup it would be much appreciated.

Thanks