Homopolar generator information

[zoobyshoe]

Binki,

Would the voltage/amperage ratio be closer together if you used a less powerful magnetic field? Or would that cause a drop in voltage as well?

 

[zoobyshoe]

Another solution to the voltage vs amperage problem occurred to me today, Binki. Since you doubled the voltage in your machine by using two disks it should be possible to take that very much farther. You could construct the conducting rotor as a sandwich of many very thin layers of conducting metal separated by thin layers of anything non-conducting. Aluminum foil is about .0005 inches thick and most metal is available in thin sheets or rolls from .001 on up. Using the cheapest and thinnest, aluminum foil, you could fit 125 layers in a mere eighth inch with a comparably thin insulation between them. 125 x 3 volts per layer = 375 volts right from the starting gate. I don't believe the amperage could be very high from such thin conductors.

Does this make any sense given what you know from your experience?

-Zooby

P.S. I am still curious about how the magnetic field was oriented in your machine. You haven't explained the orientation of the poles yet.

 

[Binki]

Zooby

Dont forget that in order to get two disks mounted on the same shaft each had to be completely contained in opositely oriented fields because they were rotating in the same direction. This is more complicated than it seems, I will try to send a diagram.

Binki

 

[Binki]

Zooby

Voltage is directly related to flux density.

Here is a very quick sketch, it is not very neat but maybe you will get the drift from this sectional view. The two units are magnetically independant which is the only way to put them in series and double the voltage.

As to you other comment on the current drawn fron a thin conductor: The current is only limited by the load capacity of the conductor before losses i.e. copper has a limit before heating of 3000 Amps per square inch of conductor. If you were able to draw more current than the capabilities of the conductor you obviously reach a meltdown point.

Binki

 

[zoobyshoe]

Thanks for the sketch, Binki. Your machine is much more complex than I thought, and I still don't quite understand how it worked, but I'm more clear on the setup.

You say the voltage is tied to the flux density. In a normal generator voltage is tied both to the number of turns and the speed of rotation. What does faster rotation do in the homopolar dynamo? Increase the amps?

 

[Binki]

Zooby

Revise a little bit the calculation for generating a VOLTAGE: Speed, Field strength, Conductor Length.

Speed relates to only one conductor on the faraday disk as oposed to being multiplied by the number of turns in a conventional generator.

Field strength (Gauss) is the same for both systems - although optimizing is recomended in the farady disk for the above reason.

Conductor Length is the radius of the disk (within the field) whereas in the conventional generator this is multiplied by the turns.

Amperage can be drawn from both systems up to the limits of the conductors (Before they burst/burn out. Lower resistive load=Higher Amperage drawn.

 

[Binki]

Zooby

From the textbooks

Voltage=number of lines of force cut per second divided by 100,000,000

Binki

 

[zoobyshoe]

Thanks, Binki, that makes sence.

My impression from your sketch is that the coils created a pole over the whole area of each side of the disks, all north on one side and all south on the other side of the disk. Is that how it was?

I'm still working on that other test. Something blew in my lathe motor controls and I have been playing with ways to make a new control system. Figured it out tonight and will put the lathe back together tomorrow. (It's almost one A.M. here.)

Zooby

 

[Binki]

My impression from your sketch is that the coils created a pole over the whole area of each side of the disks, all north on one side and all south on the other side of the disk. Is that how it was?
Zooby

Yes, but don't forget that the faraday disk was also iron like the rest of the magnetic circuit, the only gap in the magnetic circuit was the famous 5mm gap all the rest was iron, so you get a perfectly even magnetic field.

Binki

 

[zoobyshoe]

Oh. I didn't catch that about the disk being iron before. That certainly complicates what was going on.

Do you think that in a conventional Faraday generator, which has the magnetic field in just one spot, like Faraday had, would work with my notion of the sandwich of thin conductors to multiply the voltage?

 

[Binki]

Zooby

Here's a fresh and better diagram of just one side of a rotor

Binki

 

[Binki]

Oh. I didn't catch that about the disk being iron before. That certainly complicates what was going on.

Do you think that in a conventional Faraday generator, which has the magnetic field in just one spot, like Faraday had, would work with my notion of the sandwich of thin conductors to multiply the voltage?

Zooby

the disk being iron or any other conducting material is not imortant, if we had placed a copper disk in the centre we would have had to increase substantially the field windings in order to keep the field strength at a maximum.

About your sandwich idea, remember you will achieve oposite charges between axis and outer edge of the disk, you can only invert this direction by inverting the field and then you can place each disk series with each other like a pack of batteries +-+-+- and the only way you can invert the field without influencing each other is to isolate each unit magnetically, which is what I did in my experiment but two disks is allready mechanically cumbersome.

Binki

 

[zoobyshoe]

Yes, I understand the problem now. Each layer of my sandwich will have its own voltage, but they will simply combine in parallel, and the total voltage will be only be equal to that in anyone layer, not more. Thanks for saving me the trouble of testing that idea.

What do you expect would happen if I rotated the magnets if each magnet had both a North and South pole facing the opposit pole through the conductor? Do you think it would produce alternating current? Or would everything just cancel out and produce no current?

 

[zoobyshoe]

Here's a fresh and better diagram of just one side of a rotor

I'm still completely confused. Why are the brushes on the inside? I also have no idea about what elements were rotating and which were stationary. The plate sticking through the gap is labeled as copper. I though you said it was iron? Totally confused. Sorry.

 

[zoobyshoe]

My lathe is now running again (though not as well as it used to) and today I machined the four pulleys. I also turned the ends of the drive shaft down to fit into the ball bearings in which they will run. Tomorrow I need to make supports for the bearings and then get everything mounted together on a board. I plan to simply chuck the driveshaft into an electric drill to power the thing for the test. If all goes well I should be able to see if I can get any current out of it tomorrow.

 

[Binki]

I'm still completely confused. Why are the brushes on the inside? I also have no idea about what elements were rotating and which were stationary. The plate sticking through the gap is labeled as copper. I though you said it was iron? Totally confused. Sorry.

I have explained all this before, but in order to make it clearer:

The copper conductor is the support for the coils and the brushes and it is stationary(the coils and brushes also).

The brushes draw current from the edge of the (so-called)F/Disk but you are seeing also is the iron keep surrounding the brushes and coils giving the whole rotating assembly a much larger aspect. The iron keep is essential in order to give a return path for the field and therefore maintain the field strength. The whole iron keep rotates(because it is part of the f/Disk), therefore it is necessary to have a gap in order to pass out the current. As I have already stated I cannot prove that the generation of current is in the f/Disk or in the gap, this depends on whether the field rotates or not!

Binki

 

[zega]

Here i will attach a picture of my experiment with homopolar generator...
I have NdFeB magnet 7cm diametar and 1cm thickness, field is around 0.4Tesla at the edge little bit lower at center, it is zinc coated, that zinc i used as conductor...
In this setup i spun a magnet that holds itself on fan steel cup rotor, RPM is around 1500...
Voltage i get from it range from 50-100mv depending on speed (how mutch i press the copper wire contact, rotor slows down, voltage drops) oscilloscope input is straight (no probe) terminated with 50ohm terminator to avoid static, and spikes on waweform are there on purpose to avoid confusion regarding people that don't believe that voltage is available from this setup (so they cannot claim that i just rise a line on scope via zero/offset knob on scope), so i pressed wire contacts little bit lighter for you to see both zero and max voltage because of weak contact, if i use proper force to obtain good contact line becomes solid...
Here is a pic...
ZEGA

 

[zoobyshoe]

OK, I finally understand. It is quite a bit more complicated than you realize. No doubt you are used to it, but it is nothing like any other homopolar generator I have read about.

I can see how it is so difficult to tell if the field is rotating or not.

 

[zoobyshoe]

zega,

Did you check for how much amperage seemed to be available from it?

Yours is like my second set up: magnet + conductor, in which I did manage to get a very tiny voltage and current. You got much more. I have no way to measure the strength of the magnet I used, but yours is probably stronger. My magnet was slightly larger in dia. : 7.459 cm.

Question: what is the material of the brushes you are using to make contact with the rotating magnet?

Edit: I see you already mentioned that "copper wire contacts". This is one difference. I used carbon brushes.

So let me ask what the orientation of the magnetic field is on the magnet? Is this magnet from an audio speaker?

 

[zega]

I have tried to shunt it with 0.1ohm and manage to get around 1/3 of the no shunt voltage, that is around 0.2 amps...
Limiting factor was thin wires, thin zinc coating, and overall high internal resistance of the system (it is all known in electrical engineering).
Magnet is full disc (as you can see) custom fabricated in China for me, i bought a big bunch of Neodymium magnets in china for some stuff and added this round magnets for experimenting...
It is very strong, i have borrowed gaussmetar and measured them, and i constructed and made my own gaussmetar with quad OP and hall from VCR, some magnets i got can pull 500KG (around 1000lbs) dimensions 10cmx3cmx1.5cm orientation trough 10x3 thickness and magnets are VERY dangerous...
These round magnet i oriented trough thickness (1cm) as you can see in experiment via contact placement and waweform...
All in all i plan to make two faraday generators combo in one that has edges rubbing each other at 20000RPM-s and brushes at the centers to minimise power loss due to the friction...
In center there is no high angular velocity so frictional power loss is mutch mutch reduced...
Even then if i manage to get 1-2 Volts i do not expect to run full circle because it is not that efficient...
If there is OU effect in this device i count for at least 5V out and high current (around KA) capability that can be used to close a loop...
But that kind a device is very expensive and i cannot afford it...
I plan to use this small device to test it to the power increase regarding no current drawn spinning condition, and increase in mechanical load when i increase loading of the device, to see if there is a proportional ratios, if there are no proportional ratios i will then consider making larger device to satisfy my curiosity and maybe something else...
ZEGA

 

[zoobyshoe]

Zega,

You sound quite dedicated to these projects.

Those powerful magnets you got sound awesome.

I'm curious to know how you think the current that you got from the set up in the picture was generated.

Have you read Tesla's report of his experiments with unipolar dynamos? I just reread it today and found it all extremely interesting in regards to this thread.

Zooby

 

[zoobyshoe]

Binki,

I finally ran my set up today, and to my disapointment, it generated no voltage and no amperage.

This is the one where the magnets alone are rotated. I was kind of amazed that there wasn't the slightest reaction in the meter, and I kept switching it back to the ohms setting to make sure there was continuity in the circuit, which there always was. Rotating the magnets alone apparently generates no current. This tends to support the notion that the field doesn't rotate. I can't say it proves it, because there may be some other effect at work I'm not aware of. By all acounts, if I were to take the same set up, hold the magnets still and rotate the conductor, I should get the usual very high amperage and minimal voltage. It strikes me as perverse that the reverse doesn't seem to also be true.

I guess my next step should be to do just that: hold the magnets still and rotate only the conductor. That should generate definite, indisputable current according to what several sources say, Tesla included. If it doesn't there must be something quite wrong with my set up I'm not aware of.

Zooby

 

[zoobyshoe]

In his article; Notes on a Unipolar Dynamo Tesla starts by discussing what he finds interesting about the Faraday machine when run as a motor. He is fascinated by the fact that no mechanical or electrical alteration of the field is necessary to produce motion: simply run current through the disk and it turns, no alternating current, no commutators.

It occurred to me that, as a motor, the Faraday disk is simply a variation of the effect Faraday observed when he ran current through a wire suspended over a magnet, with the wire making contact with a dish of mercury that was grounded to the same battery, if any of you know that experiment. It is considered to be the first motor ever invented.

A guy who used to post here alot, named Ambitwistor, explained to me that the wire/magnet/mercury motor was easily explained in one of Maxwell's equations, and the motion resulted from the torque experienced on a current carrying conductor which is always at right angles to the direction of current flow in a magnetic field. The same is obviously true of a disk carrying current in a magnetic field, which behaves like a mass of current carrying wires all oriented so the current flows from the axis of rotation to the periphery, or from the periphery to the axis. Instead of mercury, brushes are used to complete the circuit in the case of a disk.

Tesla published this article in 1892. He frankly admitted he didn't understand what was behind the operation of this kind of motor, which must mean he wasn't familiar with Maxwell's work. I'm not sure how well accepted Maxwell was in general at this time anyway. He was right, though, that it works on a very different principle than all other motors.

 

[zoobyshoe]

In the same article, Notes on a Unipolar Dynamo, Tesla goes on to say:

"Considered as a dynamo machine, the disc is an equally interesting object of study. In addition to its peculiarity of giving currents of one direction without the employment of commutating devices, such a machine differs from ordinary dynamos in that there is no reaction between armature and field. The armature current tends to set up a magnetization at right angles to that of the field current, but since the current is taken off uniformly from all points of the periphery, and since, to be exact, the external circuit may also be arranged perfectly symetrical to the field magnet, no reaction can occur. This, however, is only true as long as the magnets are weakly energized, for when the magnets are more or less saturated, both magnetizations at right angles seemingly interfere with each other.

"For the above reason alone it would appear that the output of such a machine should, for the same weight, be much greater than that of any other machine in which the armature current tends to demagnetize the field. The extrordinary output of the Forbes unipolar dynamo and the experience of the writer confirm this view."

This much greater output of the unipolar dynamo must be the origin of the rumors of Over Unity. Notice, however, that Tesla states this lack of reaction between armature and field only occurs when he "magnets are weakly energized". He says that when the magnets are more or less saturated this effect is destroyed.

The rest of the article is extremely interesting. He was a very thorough experimenter and writes fairly clearly on a complex subject.

It is contained in the book The Inventions, Researches and Writings of Nikola Tesla compiled by Thomas Commerford Martin, published by Barnes and Noble. The paperback edition I have is from 1995, there may be more recent ones. I have seen it for sale in many places and am sure you can get it online from Amazon.

 

[Binki]

Zooby

About your experiment: If the field was rotating it would be generating the oposite current in the stationary plate and the external circuit, so would be giving you a null result. But I am inclined to believe the field doesn't move.

Binki

 

[zoobyshoe]

About your experiment: If the field was rotating it would be generating the oposite current in the stationary plate and the external circuit

Hmmmm. This, I don't follow. Why should there be an opposite current in the external circuit?

 

[Binki]

Hmmmm. This, I don't follow. Why should there be an opposite current in the external circuit?

If the field is turning, you don't have it contained in any sort of way and the lines of force return to the oposite poles of your magnets. they pass through a very large area of space around your experiment you can follow them to some extent with a normal magnetic compass and you will find that your external circuit will be cut by exactly the same number of lines as the part you believe to be generating. (the analogy to lines in a magnetic field is only a way to understand the field strength. You will see iron filings form lines but it doesn't mean that the lines exist in the field)

Binki

 

[Binki]

Zooby

Let us go a little further in this subject of whether the field turns or not.

Lets assume that it does just for a moment and imagine that large fat ball or donut shape field is rotating and passing through all the surrounding materials some will be conductors and others not and still others may be material that are to some extent magnetic in themselves. What is happening as the lines of force are traveling through these materials? Wont they will be generating current that in turn opposes the movement of the field? I think so and this is exactly why I believe that the field will not turn when you rotate the magnet on its axis because in effect it is anchoring itself to everything around it. You will need to give the field more incentive in order to rotate it!

 

[zoobyshoe]

What is happening as the lines of force are traveling through these materials? Wont they will be generating current that in turn opposes the movement of the field? I think so and this is exactly why I believe that the field will not turn when you rotate the magnet on its axis because in effect it is anchoring itself to everything around it. You will need to give the field more incentive in order to rotate it!

Everything is either magnetic, diamagnetic or paramagnetic. However only good conductors generate enough counter EMF to be of consequence. If you were to spin a bar magnet 20 cm long, North on one end, South on the other, on an axis located between the two poles, with no conductors withing a meter of it, but plenty of other non-conducting material, the most resistence you would get would be from air friction.

Rotating the magnets as I did shows either that the field doesn't rotate or some other cancelling effect we haven't thought to test.

Anyway, I should have my setup where only the conducting disk rotates ready to test today. If this set up (uniform field over the whole area of both sides of the disk) generates a current then it will constitute a strong indication that the field does not rotate when you rotate the magnets.

 

[Binki]

Tesla published this article in 1892. He frankly admitted he didn't understand what was behind the operation of this kind of motor, which must mean he wasn't familiar with Maxwell's work. I'm not sure how well accepted Maxwell was in general at this time anyway. He was right, though, that it works on a very different principle than all other motors.

As far as I Know about Tesla that he studied all the known information on electricity of his time in colleges in his native Yugoslavia. Faraday was some 40 years before and it was Maxwell as a mathmetician that put into formulas Faradays research.

Binki

 

[Binki]

Everything is either magnetic, diamagnetic or paramagnetic. However only good conductors generate enough counter EMF to be of consequence. If you were to spin a bar magnet 20 cm long, North on one end, South on the other, on an axis located between the two poles, with no conductors withing a meter of it, but plenty of other non-conducting material, the most resistence you would get would be from air friction.

Dont forget we are dealing with a subject that could have much wider conotations and that thrashing a magnetic field back and forth north to south etc has no bearing -in my mind- on a homopolar system. You have already quoted Tesla's surprise to the faraday motor effect and quite frankly I don't believe that we now have any greater undestanding than then.

Binki

 

[zoobyshoe]

As far as I Know about Tesla that he studied all the known information on electricity of his time in colleges in his native Yugoslavia.

I think you'd be interested in the unipolar dynamo he designed and built. It was actually two separate ones right next to each other connected in series to increase the voltage. They were on separate parrallel shafts, not on the same shaft like yours. They were the same except that he changed the direction of the exiting field on one of them so that he could run them both in the same direction by means of a conducting band that was looped around the periphery of both conducting disks. This allowed him to only make connections to the rotating shafts. This is something like what Zega wants to make with the two disks touching as they rotate. That sounds like a very good idea to me, because you double the voltage and solve the friction problem with brushes on the periphery of the disks. I think Zega's way you could gang them up indefinitely.

 

[zoobyshoe]

Dont forget we are dealing with a subject that could have much wider conotations and that thrashing a magnetic field back and forth north to south etc has no bearing -in my mind- on a homopolar system. You have already quoted Tesla's surprise to the faraday motor effect and quite frankly I don't believe that we now have any greater undestanding than then.

Binki

I agree that the unipolar dynamo is different. I am questioning your explanation of the mechanism whereby the field doesn't rotate. It obviously moves nearly instantaneously in response to any motion that is not along the axis of magnetisation; any non-north-south movement. It seem exclusively to be non-rotational on the north-south axis.

Anyway, today I tried the next set up: rotating the conducting disk while the magnets were stationary.

I was appalled at the miserable results.

Much like in my second set up, the needle on the meter gave only the slightest response.

Due to reports of huge amperage, I started with a slow drill as my driving motor, and had the meter set on the highest amp level. No response. I clicked the meter down to microamps and put the drill on full speed: 550 rpms. The needle moved up to about 20 microamps. I changed to a different drill which goes up to 1200 rpms and ranked it up full speed. This only managed to double the amperage to about 40 microamps.
--------
Why is it I'm not getting the famous unipolar amperage?

I made the disk to more or less match the size of the magnets I was using, but a little larger to make sure the brush contacted the disk and not the magnets.

The disk is aluminum, very close to 9 cm in diameter and 9 mm thick. It is mounted on a shaft of aluminum 1/2 half inch (1.27 cm) in diameter. The magnets are, as I said before from audio speakers and are quite strong; finger pinching strong - you have to be careful putting them together.

The continuity through the circuit was aways fine when I checked it. The brush was the same carbon brush taken from an electric mixer motor I used in the other set up.

I realize that the diameter is quite a bit smaller than yours, and most, but I find it hard to believe this could account for my results. I would expect to have gotten at least a full amp, since the drills were drawing more than that.

The only thing I can think of that I know for sure is different is the thickness of the disk. It is quite a bit thicker than any I've read about. I have seen pictures of Faraday's disk and it doesn't look to be more than 3mm thick.

What do you think, Binki?

 

[Binki]

I agree that the unipolar dynamo is different. I am questioning your explanation of the mechanism whereby the field doesn't rotate.

I Just had a little bit of inspiration at the time and it seemed like a good explanation because we don't know how much the field is anchored to the magnet anyway, the space through which the field travels may have a greater influence on it than the source of the field - Just another hypothesis without proof I'm afraid.

I was appalled at the miserable results.
Why is it I'm not getting the famous unipolar amperage?

Remember the return path of the field will be counter productive - we can supose that aproximately half the field will return through the hole in the centre of your magnets which is part of your generating conductor and the other half or maybe a little more take the easy way round on the outside which it seems you have contemplated by making the disk just a little larger than the magnets but still it will have some counter effect.

The disk is aluminum

Not the best for contacts but is a good conductor, remember that Aluminium oxide is a very good insulator but as you have said you seem to have a good continuity(copper would be better).

The magnets are, as I said before from audio speakers and are quite strong; finger pinching strong - you have to be careful putting them together.

If they are ferrite ceramic magnets you will find the probable field strength on the web (I think approx 4000 Gaus ie. 4000 lines per square cm). Do your sums to check the voltage that should be given by the formula that I sent before. You can actually calculate the field strength and or voltage if you can rely on your speed measurements.

The only thing I can think of that I know for sure is different is the thickness of the disk. It is quite a bit thicker than any I've read about. I have seen pictures of Faraday's disk and it doesn't look to be more than 3mm thick.

the thickness shouldn't make any difference except that the further apart your magnets are the lesser the field strength. Try to assemble some sort of soft iron keep in order to controll the return path of the field and you will probably allready be generating a lot more current.

Binki

 

[zoobyshoe]

I Just had a little bit of inspiration at the time and it seemed like a good explanation because we don't know how much the field is anchored to the magnet anyway, the space through which the field travels may have a greater influence on it than the source of the field - Just another hypothesis without proof I'm afraid.

It seems pretty well completely anchored to the magnet to me, except for this maddening, apparent non-rotation around the North-South centerline. Perhaps this can be explained if we think of a permanent magnet as having exactly the same rotation of authentic current going on inside of it as a coil of conducting wire. Something like this logic: of course you're not going to find any rotation when you physically rotate the magnet because the electrons inside the magnet are already rotating around that axis, virtually, even when the magnet is stock still, faster than anyone will ever be able to physically rotate the magnet to begin with.

By the same logic, no one could physically rotate the magnet in the direction opposite to the direction the electrons are rotating fast enough to demonstrate any slowing in that direction.
I think the speed we're talking about here is c or close to it: the speed an electron orbits a nucleus. I'm not sure about that though. Can't be faster. We know that at least. Might be somewhat slower.

I actually like that explanation. The field doesn't seem to rotate with the magnets because it is already rotating on that axis at near light speed to begin with, so smoothly and with no change in the number or intensity of lines that it does not induce current in conductors. Rotate the magnet in the opposite direction all you want, you'll never be able to go fast enough to percieve any slowing.

Remember the return path of the field will be counter productive - we can supose that aproximately half the field will return through the hole in the centre of your magnets which is part of your generating conductor and the other half or maybe a little more take the easy way round on the outside which it seems you have contemplated by making the disk just a little larger than the magnets but still it will have some counter effect.

Good catch, Binki. I didn't even consider this. I actually have room to turn the disk diameter down some more, too. Come to think of it. I could make it just a touch smaller than the magnets and file the brush thin enough to fit between them.

Not the best for contacts but is a good conductor, remember that Aluminium oxide is a very good insulator but as you have said you seem to have a good continuity(copper would be better).

I didn't think about the Aluminum oxide either. That would certainly be a consideration in the fine tuning stage. At this point I don't think it could be the big problem.

If they are ferrite ceramic magnets you will find the probable field strength on the web (I think approx 4000 Gaus ie. 4000 lines per square cm). Do your sums to check the voltage that should be given by the formula that I sent before. You can actually calculate the field strength and or voltage if you can rely on your speed measurements.

Hmmm. Speed measurements? Have no capacity to really do this. I'm just figuring + - 100rpms the drill rating at max speed.

the thickness shouldn't make any difference except that the further apart your magnets are the lesser the field strength.

This is good to know, because the thinner I have to make it the less sturdy it will be on the shaft. It is simply press fit on there. I was thinking earlier that if thin was better I would have to make a whole different shaft: two parts, one screws into the other with the disk held between. More work.

Try to assemble some sort of soft iron keep in order to controll the return path of the field and you will probably allready be generating a lot more current.

Sounds like an excellent idea. What sort of arrangement do you suggest? It wouldn't be a problem to do just about anything involving flat disks, or disks with steps. I couldn't machine anything with a curved profile, though, like your plates. Except very roughly. The holes through the magnets are 3.175 cm in dameter. Quite a bit larger than the shaft.

Zooby

 

[Binki]

Use two square iron plates a little larger than your disk and brush assembly with a hole in the centre for the shaft then join the two top and bottom with other plates. The magnets will stick themselves to the plates with holes. you obviously already have supports for your magnets, I don't know how these would conflict

Binki

 

[zoobyshoe]

Use two square iron plates a little larger than your disk and brush assembly with a hole in the centre for the shaft then join the two top and bottom with other plates. The magnets will stick themselves to the plates with holes. you obviously already have supports for your magnets, I don't know how these would conflict

Binki

The plates go between the magnets and the rotating conducting disk, or on the other side of the magnets farthest away from the conducting disk?

I understand about the top and bottom pieces.

Thanks,

Zooby

 

[Binki]

The plates go between the magnets and the rotating conducting disk, or on the other side of the magnets farthest away from the conducting disk?

I understand about the top and bottom pieces.

Thanks,

Zooby

Outside of the magnets

Binki

 

[wolfblum]

Hi Everyone, (I'm new here and like your interest in Acyclic EM interactions!)

Anyway, I've performed thousands of experiments involving homopolar, unipolar, and acyclic generator and motor topologies. They all are real and work (i.e., they produce EMF or MMF predictably.)

Don't use carbon brushes (the brush drop will exceed the induced EMF or back-EMF, which is usually max. 50mV-100mV, depending on your peripheral displacement velocity of your translating disc or other conductor, it's median length and of course the flux density of your magnetic field that you supply, which is not likely to be much more than 1 Tesla, or @10,000 Gauss!)

If you want quantitative and reproducible results, use copper braid brushes (cheap) and no!, the observed EMF in the case of an acyclic generator is not due to thermal/frictional etc. effects. Copper on copper provides minimal brush loss (and further, that's why all the high-energy research efforts (read US Military) have used eutectic (i.e., liquid metal, such as mercury etc.) current collectors to minimize such losses.

In any event, acyclic topologies are certainly not overunity, but yes, they are low-impedance (i.e., high current/low voltage, as someone observed earlier on on this forum), and they also do provide a source for a great many apparent paradoxia when viewed in light of inertially constrained relativistic quantum electrodynamics, yet they don't when properly viewed in non-inertial frames (i.e., rotational non-relativistic QED.)

The question as to whether a cylindrical and symmetrically uniform magnetic flux field does or does not rotate (i.e., rotationally translate) about it's physical macroscopic axis has never been definatively answered or proven (ask me for the reasons/paradoxical explanations), but they might soon be. Several groups are working on developing very small and independant "observer" platforms that may "ride along" atop or with a homopolar/acyclic generator disc and relay it's own action observations to a stationary (i.e., laboratory or observer frame) via radio or optical means.

We are getting very close ourselves in this regard, but won't know until later this fall!

Anyways, sorry for my lengthy diatribe, just one more comment to an earlier poster on this forum (and good on you!), and to paraphrase you (sorry I don't remember your name right now), "you couldn't spin a magnet fast enough" (physically) to approach relativistic effects to second order on the face of this planet! I like it - Wolf

 

[zoobyshoe]

Hi Everyone, (I'm new here and like your interest in Acyclic EM interactions!)

Hi, wolfblum,

'Acyclic EM interactions"? A new term to me. What's the specific definition?

If you want quantitative and reproducible results, use copper braid brushes (cheap) and no!, the observed EMF in the case of an acyclic generator is not due to thermal/frictional etc. effects. Copper on copper provides minimal brush loss (and further, that's why all the high-energy research efforts (read US Military) have used eutectic (i.e., liquid metal, such as mercury etc.) current collectors to minimize such losses.

Good to know. I had no idea it might make a difference. I've just been reading the original Faraday and he amalgamated the perifery of the copper plate as well as the copper brushes.

In any event, acyclic topologies are certainly not overunity, but yes, they are low-impedance (i.e., high current/low voltage, as someone observed earlier on on this forum), and they also do provide a source for a great many apparent paradoxia when viewed in light of inertially constrained relativistic quantum electrodynamics, yet they don't when properly viewed in non-inertial frames (i.e., rotational non-relativistic QED.)

Cool.

The question as to whether a cylindrical and symmetrically uniform magnetic flux field does or does not rotate (i.e., rotationally translate) about it's physical macroscopic axis has never been definatively answered or proven...

I'm glad to hear this, because I couldn't find any rotation of the field with the magnet. I'm glad to know there isn't some obvious answer I stupidly missed.

Anyways, sorry for my lengthy diatribe, just one more comment to an earlier poster on this forum (and good on you!), and to paraphrase you (sorry I don't remember your name right now), "you couldn't spin a magnet fast enough" (physically) to approach relativistic effects to second order on the face of this planet! I like it - Wolf

You may be referring to something I said, but you have generously imbued it with more sense than it had when I said it. That's OK, as long as you find some inspiration in my loose speculation. I have a feeling the answer is going to be found by some variation of this way of looking at it. My point, if I recall it, was something to the effect that the reason rotation can't be detected is that the field is already rotating in some important, but not obvious, way even when at rest. It is probably physically impossible to rotate the magnet at a speed where a increase in the speed of that "at rest" rotation could be detected. The "at rest" rotation I have in mind is something like a combined effect from the zillions of electric field lines that are all being towed in in circles, in the wake of their respective electrons as they orbit. I hope that's not too whacky.

 

[wolfblum]

Hello Zooby,

I don't know how to do those nice quote panes yet, so please bear with me.

"Acyclic EM interactions"? A new term to me. What's the specific definition?

Acyclic Electromagnetic interactions are those that are time invariant (as in any true homopolar machine.) This, as opposed to the Cyclical (time varying) EM interactions found in all other electromagnetic machinery (AC or DC.)

As an example, a copper disk rotating perpendicular to an applied uniform and symmetrical magnetic flux field will never experience any flux density variations (or polarity variations.) Cylindrical topologies are also possible, as you already know.

As a result, the conduction electrons in the disk (i.e., the so-called free electron gas) experience the Lorentz force and a displacement current flows, leading to the EMF gradient observed between the center and periphery of the disk.

Please do not amalgamate anything, mercury is nasty stuff! Faraday used to lick his experimental apparatus to have his tongue "sense" electric potential, that's what probably caused his mental and health problems in later life and his death. FYI, I have a complete original set of Faraday's diaries and can tell you that he did co-rotate a disk with a cylindrical magnet and observed the generation of EMF (although he was never certain himself about the rotation of the field itself.)

Further stuff, the term unipolar should not be used, it means "having one pole" and that is not possible. The term homopolar is acceptable and means "poles on the same center." One has to be carefull though, for example, most of Faraday's reported disk experiments may well be classified as homopolar, in that the magnetic poles were on the same center, however, they were not acyclic, in that the rotating disk axis was not on the magnetic pole axis. So the EMF that Faraday measured was really due to eddy currents (if he had been able to measure drag torque as he turned the disk faster and faster, even with no brush connections and external circuit, he would have noticed the required effort increase and that the temperature of the disk was also rising. Hmm... just the exact same setup as the brake disk in our electric watthour meter on the side of the house!)

I'll comment more on the "spin" aspects involved in magnetic fields later.

Ciao - Wolf

 

[zoobyshoe]

Acyclic Electromagnetic interactions are those that are time invariant (as in any true homopolar machine.) This, as opposed to the Cyclical (time varying) EM interactions found in all other electromagnetic machinery (AC or DC.)

I think I get the concept. What branch of study does this term come from?

Please do not amalgamate anything, mercury is nasty stuff!

Good advice. Don't worry.

Faraday used to lick his experimental apparatus to have his tongue "sense" electric potential, that's what probably caused his mental and health problems in later life and his death.

I think you could well be right. I read him speaking about "the flash", which apparently was a flash of light in the field of vision when he got a particularly strong shock from touching his leads to his tongue. He simple considered it a measure of of current and seemed to have no conception it might be dangerous.

FYI, I have a complete original set of Faraday's diaries and can tell you that he did co-rotate a disk with a cylindrical magnet and observed the generation of EMF (although he was never certain himself about the rotation of the field itself.)

I'm quite envious. When you say "original" you mean first edition? I'd be happy to have any edition of them. Haven't discovered where I might get them. I just happened to find these published experimental findings of his last week, and I am amazed, page after page, by how thorough and meticulous he was, leaving no potential question unanswered, exploring every possible angle of every phenomenon.

I think it would be great, if you had the time, if you could quote the text of that particular experiment, if it isn't too long. So far, I haven't found anything about it in the book I have.

Further stuff, the term unipolar should not be used, it means "having one pole" and that is not possible.

I see what you mean.

Are you interested in the homopolar dynamo for theoretical reasons or for engineering?

-Zooby

P.S. To quote you hit the "quote" button at the bottom of the post you want to quote from and respond to. To quote a section you write QUOTE in brackets in front of the first word of the quote, and /QUOTE in brackets after the last word of the quote.
You write your own reponses just like in a normal post with nothing in brackets.

You can delete anything in the person's post you don't need to respond to.

At the bottom there is a place to select "Preview Post". This will show you what your finished post will look like without actually submitting it. If it looks OK, and you have made all your quotation brackets properly, you can hit submit. If you need to correct you just scroll down to the box where the text is waiting to be corrected.

 

[wolfblum]

Zooby, Thanks for your helpfull guidance on quotes etc.

The term acyclic is a general physics term you would see most often used in biology / chemistry, but it simply means what it means, i.e., no cyclical variation of a parameter, in our case magnetic flux density (or polarity.)

Faraday and others investigators of that era did things that we all now know are incredibly dangerous, but that's how it was back then. I sometimes chuckle and sometimes scream (e.g., the Curies!)

As far as "Faraday's Diary" is concerned, there is of course only one original set by him (bequeathed to, and in the possession of the Royal Institution in London. BTW, I have been there and snooped extensively, lots of forgotten and misconstrued stuff on exhibit, ask me sometime!)

There was one transcription and printing thereof (i.e., there was only one edition), and it was over a period of 1932 to 1936 by G. Bell and Sons of London (wait I have to run downstairs and check... yes, eight volumes total, last one index, two volumes apparently printed per year.)

Zooby, depending on what country/state you are in, you might be able access the set at a University library. If you want, let me know your rough location and I can run it through the International library database. It's funny, there are apparently seven sets here in Canada (mine appears to be the only private one) yet in the rest of the world there are precious few (i.e., UK six, Japan two) and yet in the USA there are dozens in University repositories.

The Faraday's Diary set is somewhat hard to find and purchase, I know of booksellers who own two or three volumes, will not part or sell with them under any circumnstances, and yet are hoping and seeking to buy the missing volumes to complete their set! I was very, very, very lucky many years ago, my set was for sale on ebay by a collector in Toronto and appeared to be leaving the country. I bid it up to around U$1200.- and got it (most of the bidding was from European book antiquarians)! I was happy, but even more so when two years I went to London to visit the Royal Institution (and for some other books) and found out that the last set sold on the open market for several thousand pounds. Sorry, I shouldn't be so gleefull.

In any event, if there is such interest in Faraday's EM researches and findings relating to and surrounding his homopolar/acyclic experiments (they occurred primarily in 1821 and 1831-32), I think I would be prepared to post the text of his relevant experiments on this forum. Mind you, I don't want to overload this forum venue either. So I propose to perhaps post one important experiment per week (this should keep the final total number of posts to about 60 or so.) I will not do this unless there appears to be some positive endorsement and agreement by the forum group as a whole.

As to the specific experiment I referred to and that you refer to Zooby, that one is very enlightening and I will post it over the next few days, OK?

Lastly, Zooby, I'm interested in acyclic/homopolar machinery from both a theoretical and practical viewpoint, hence my research over the past ten years or so - Wolf

 

[zoobyshoe]

As far as "Faraday's Diary" is concerned, there is of course only one original set by him (bequeathed to, and in the possession of the Royal Institution in London. BTW, I have been there and snooped extensively, lots of forgotten and misconstrued stuff on exhibit, ask me sometime!)

Wow! That must have been fun!

There was one transcription and printing thereof (i.e., there was only one edition), and it was over a period of 1932 to 1936 by G. Bell and Sons of London

It's amazing to me there haven't been more editions.

Zooby, depending on what country/state you are in, you might be able access the set at a University library. If you want, let me know your rough location and I can run it through the International library database.

San Diego, Ca.

Sorry, I shouldn't be so gleefull.

Don't be hard on yourself. In your shoes, I would be insufferable.

So I propose to perhaps post one important experiment per week (this should keep the final total number of posts to about 60 or so.) I will not do this unless there appears to be some positive endorsement and agreement by the forum group as a whole.

Hmmm. My assessment is that the people interested would more likely form a small, enthusiastic group. Faraday is under- appreciated around here in my opinion and there is also a lack of interest in reading anyone's original papers for some reason.

Since you're willing to make the effort to copy them, though, it would be a shame not to get them onto the web somewhere. There is a lot of interest at large in homopolar dynamos and Faraday.

What is the copyrite situation with these diaries? Any chance they're in the public domain?

As to the specific experiment I referred to and that you refer to Zooby, that one is very enlightening and I will post it over the next few days, OK?

That would be great. I'm looking forward to it. I had decided it must not be true before you came along.

Lastly, Zooby, I'm interested in acyclic/homopolar machinery from both a theoretical and practical viewpoint, hence my research over the past ten years or so - Wolf

My own interest is practical. I'm fascinated by how simple they are. I have a penchant for reducing things to the lowest possible level of complexity, labor, and expense, and maintenence. It's a kind of laziness, I guess.

 

[wolfblum]

Wow! That must have been fun!

It was amazing to see some of Faraday's original experimental apparatus and his laboratory (in the basement of the Royal Institution, almost a dungeon I might add!)

It's amazing to me there haven't been more editions.

There was only the one printing, also I don't think anyone has even attempted a Project Guttenberg on the diaries, because the most important and amazing part of them are the many, many margin drawings and illustrations Faraday made throughout. There have been text only attempts for small partial periods of the diary, but that's about it. I'll come back to this later 'cause of your post Zooby.

San Diego, Ca.

Aha, San Diego State U. has a copy. You should be able to at least view.

Hmmm. My assessment is that the people interested would more likely form a small, enthusiastic group. Faraday is under- appreciated around here in my opinion and there is also a lack of interest in reading anyone's original papers for some reason.

Point taken, I'll hold back until we see what we should do (except for the specific set of experiments from 1831 that I promised.)

Since you're willing to make the effort to copy them, though, it would be a shame not to get them onto the web somewhere. There is a lot of interest at large in homopolar dynamos and Faraday. & What is the copyrite situation with these diaries? Any chance they're in the public domain?

If there is such an interest, I might be willing to start a most interesting project. The copyright situation isn't an issue, and as I said above, only little bits have made it into the public domain. Let me warn everyone though, as simple as acyclic/homopolar machinery may seem, this subject leads to the involvement of the likes of Ampere, Barlow, Foucalt, Siemens, Kirchoff, Tesla, Lorentz, Einstein (yes!, his Special Theory of Relativity), Westinghouse, WWII German stuff, Feynman (Quantum Electrodynamics) and others, General Electric, the US Navy, the U. of Texas at Austin, Parker Kinetic Design, Dresser Engineers and Constructors, rail guns, plasma fusion reactors, directed energy beam weapons and pipe welding, and also the US Army (&NASA). Quite a handfull of players, don't you think?

Please give me feedback as to what we should do - Wolfblum

 

[wolfblum]

Zooby, here is the experiment by Michael Faraday on December 26, 1831.
(Faraday's Diary, Vol. 1, pp 402, G. Bell and Sons, London, 1932)

255. A copper disc was cemented on the top of a cylinder
magnet, paper intervening, the top being the marked pole;
the magnet supported so as to rotate by means of string,
and the wires of the galvanometer connected with the edge
and the axis of the copper plate.

When the magnet and disc together rotated 'unscrew'
(CCW) the marked end of the needle went west. When the
magnet and disc rotated 'screw' (CW) the marked end of
the needle went east.

256. This direction is the same as that which would have
resulted if the copper had moved and the magnet been still.

Hence moving the magnet causes no difference provided the
copper moves. A rotating and a stationary magnet cause the
same effect.

257. The disc was then loosed from the magnet and held still
whilst the magnet itself was revolved; but now no effect upon
the galvanometer.

Hence it appears that, of the metal circuit in which the
current is to be formed, different parts must move with
different angular velocities.

If with the same, no current is produced, i.e. when both parts
are external to the magnet.


I took pictures of the relevant passages and the margin drawing, but have no idea as to how to post those? - wolfblum

 

[zoobyshoe]

I took pictures of the relevant passages and the margin drawing, but have no idea as to how to post those? - wolfblum

The easiest and fastest way is to put them on a webpage somewhere and then just give us a link to the page.

It is also possible to "attach" images that will show up in a post. The problem there is that Greg Bernhardt, PF owner and administrator, wants to personally inspect all attachments before he will approve them. He wants to avoid taking up a lot of bandwidth with junk pictures, which is reasonable, but it takes him forever to get around to approving stuff. If you post the images as "attachments" therefore, it could take three or four days before anyone could see them.

I would definitely love to see what the pages look like. I'm particularly interested to see what he means by the magnet being supported "so as to rotate by means of a string."

It is quite exiting to see this whole thing described in his own words, and it clears up about two mysteries in my mind, which I'll explain after I dig up a couple quotes.

Thanks, wolfblum!

-Zooby

 

[zoobyshoe]

OK, here goes. I was reading a bio of Einstein and the author says that in the pre-relativity days there was a contradiction about the relative motion between conductor and magnet which this author attributes to Faraday's law of induction:

"This had for years been one of the accepted facts of life and to raise awkward questions about it was to spit in a sacred place. yet, Einstein pointed out, the current induced between a magnet and a conductor depends according to observation only on the relative motion of the conducting wire and the magnet `whereas the customary view', in other words, the accepted theory of currents, `draws a sharp distinction between the two cases in which either the one or the other of these bodies is in motion.' Faraday had discovered the induction law in 1834 but, as Born put it, `everybody had known all along that the effect depended only on relative motion, but nobody had taken offense at the theory not accounting for these circumstances.'"

Einstein, The Life and Times
Ronald W. Clark, p.116

In fact, this issue was very important to Einstein because the first paragraph of On the Electrodynamics of Movng Bodies, where Special Relativity made its first appearance, addresses this very thing:

"It is known that Maxwells electrodynamics--as usually understood at the present time--when applied to moving bodies, leads to asymmetries which do not appear to be inherent in the phenomena."

He is saying, in other words, that Maxwell (following Faraday's lead) misunderstood something.

"Take for example, the reciprocal electrodynamic action of a magnet and a conductor. The observable phenomenon here depends only on the relative motion of the conductor and the magnet, whereas the customary view draws a sharp distinction between the two cases in which either the one or the other of these bodies is in motion."

At this point I start not being able to follow Einstein:

"For if the magnet is in motion and the conductor at rest, there arises in the neighborhood of the magnet an electric field with a certain definite energy, producing a current at the places where parts of the conductor are situated."

First, I don't understand if he is saying this is the incorrect "customary" view, or if it's supposed to be the correct one. I haven't come across the notion that a magnet in motion produces an electric field in it's neighborhood. All I'm aware of is that a magnetic field in physical, kinematic motion can induce current in a conductor.

"But if the magnet is stationary and the conductor in motion, no electric field arises in the neighborhood of the magnet. In the conductor, however, we find an electromotive force, to which in itself there is no corresponding energy..." Huh? "...but which gives rise--assuming equality of relative motion in the two cases discussed--to electric currents of the same path and intensity as those produced by the electric forces in the former case."

Again, I can't sort out if he is presenting stuff as the erroneous "customary" view, or if he is presenting what "everybody knows" is actually happening.

Anyway, 16 pages later Einstein, having made many points, concludes this first section by saying:

"Furthermore it is clear that the asymmetry mentioned in the introduction as arising when we consider the currents produced by the relative motion of a magnet and a conductor, now disappears. Moreover, questions as to the `seat' of electrodynamic electromotive forces (unipolar machines) now have no point."

So, it is clear that he is aware of and seems to be discussing the Faraday disc dynamo. I don't know, however, to what extent Faraday's induction laws were meant to explain "homopolar" configurations, and if the strange case that you quoted is taken into account. Did Maxwell know about it, and did figuring it into his equations cause the "asymmetry" that was bugging Einstein? Or, am I barking up the wrong tree, and the asymmetry in Maxwell has nothing to do with this experiment?

-Zooby

On the Electrodynamics of Moving Bodies
Address:http://www.fourmilab.ch/etexts/eins...N=28870118&jsessionid=06302662281082217897574

 

[zoobyshoe]

It was amazing to see some of Faraday's original experimental apparatus and his laboratory (in the basement of the Royal Institution, almost a dungeon I might add!)

Yes, I can imagine this was incredible.

Aha, San Diego State U. has a copy. You should be able to at least view.

This is good to know. I wonder if they let people make photocopies of any of it? I'll have to call and see what their policies are.

If there is such an interest, I might be willing to start a most interesting project.

If you google various permutations of "Faraday Dynamo" Homopolar Dynamo" and all that, you come up with ton's of sites, indicating that there is a lot of interest at large in this particular aspect of Faraday's experiments. Quite a lot of people are crazies looking for overunity, but there are plenty of level headed researchers.

The copyright situation isn't an issue, and as I said above, only little bits have made it into the public domain.

By "Public Domain" I'm referring to the situation where the copyrite of a written work has lost all claims to be legally owned by any person or organization. Works that are in the public domain can be reprinted by anyone without anyone's permission. This happens to all books after a certain amount of time has elapsed. In some cases, though, people can take special measures to hold on to a copyrite beyond the normal time period. Some of Mark Twain's books are in the public domain, for instance, but some of his writing is not (last I heard); it is still owned by the decendents of one of his daughters, or the Mark Twain Society, or whatever.

It could be, therefore, that the Royal Philosophical Society, or the publishers of your edition, or Faraday's descendents have managed to retain the copyrite to Faraday's diaries in some way, shape, or fashion.

The thing I had in mind was to create a website on which to put the experiments that have to do with the disc dynamo, just because it would be nice to have it on the web where people could have access to it.

The other idea that occurred to me would be to collect them all into a small book, publish them yourself, and get them distributed by Lindsay Books. This is a fascinating little company that specializes in reprints of old technology books. I have ordered several dozen of their fascinating and sometimes quirky books over the years.

Lindsay distributes quite a few self-published books for people, odd ball subjects like "How To Make Tiny Drills", "How to Make Your Own Charcoal in the Backyard", "How to Melt Iron and Steel in a Backyard Cuppola" "How to Make an Entire Machine Shop from Scratch", that sort of thing. The collected disk dynamo experiments of Michael Faraday would be right up his alley.

Lindsay Publications Books Available
Address:http://www.lindsaybks.com/prod/index.html

Quite a handfull of players, don't you think?

Don't get complicated on me, wolfblum. A disc, some magnets, and some wire. That's all we need.

 

[Binki]

Faraday's Diary

Yes

The Faraday Original notes are very interesting - please don't leave me out

And it is nice to find someone else on the forum who has done some real and objective experiments with the homopolar theme

Binki