Hi,
Long ago when the late Bruce DePalma lived in Santa Barbara, CA, I've visited Bruce numerous times. His N-machines are very impressive looking. Bruce said the reason the N-machine worked was because the magnet was bonded to the disc, and therefore if DC current flows through the disc, there are two opposing rotational forces, one on the disc, and the opposite on the magnet. So if you rotate the N-machine, place a load on the disc, thus producing current, there should be no net opposing angular force on the N-machine.
That's fine, but I just tested that theory. I shorted a 30+ amp DC supply across a NdFeB disc magnet, and it rotated! My magnet is not on an axis, as it was on the carpet, but it still rotated in place.
Maybe someone who has a strong magnet on an axis could verify this as well.
Paul
I would like the results to this test as well.
I hear numerous things about the unusual fields formed by the magnets.. something about their field strength near the periphery vs that of the inside.
Quote from: PaulLowrance on December 11, 2009, 06:26:31 PM
Hi,
Long ago when the late Bruce DePalma lived in Santa Barbara, CA, I've visited Bruce numerous times. His N-machines are very impressive looking. Bruce said the reason the N-machine worked was because the magnet was bonded to the disc, and therefore if DC current flows through the disc, there are two opposing rotational forces, one on the disc, and the opposite on the magnet. So if you rotate the N-machine, place a load on the disc, thus producing current, there should be no net opposing angular force on the N-machine.
That's fine, but I just tested that theory. I shorted a 30+ amp DC supply across a NdFeB disc magnet, and it rotated! My magnet is not on an axis, as it was on the carpet, but it still rotated in place.
Maybe someone who has a strong magnet on an axis could verify this as well.
Paul
This is homopolar 101. The reason why it rotates is because both the disc (the coat of your neodymium mag) and the outside circuit (what you are brushing it against) want to torque the magnet. But since the magnet is attached to the coating this torque will vanish and all that remains is the torque due to the outside circuit, this will cause rotation. Unfortunately while rotating the coat will start generating back emf due to its motion and the presence of the magnetic field.
The interesting part which I have seen one person experiment with so far is that you can manipulate the flux of a magnet. Magnetic flux confined due to a ferromagnetic material is a very strange phenomena. You can guide it and only concentrate it on a portion of a circuit and use classic laws like the Lorentz force law to deduce force. Below you see an old concept of mine that does this. This concept though doesn't solve the back emf problem, but we know that any force has a reaction force, which in this case acts on the magnetic setup. This can cause it to rotate, so one can leave the circuit stationary and allow the setup to rotate without any bemfs where the only speed limit is component dependent.
I hear you broli. I'm only saying that this experiment goes against what Bruce told me. All these years I never even thought to question him. :'(
It would be great if someone could do this without the magnet rotating, but just make sure the friction is low enough.
This photo was grabbed online, but it looks just like my magnet. So I placed two thin stiff wires on the magnet, one on the outer edge, and one on the center of the disc. It seemed to work best on carpet. Perhaps less friction.
I have played with homopolars, they really are cool and mystifying. No back emf at all, But their greatest downfall is the contacts with rim of the disc, hence teslas novel method of having a chain drive between 2 discs, the chain or conductive belt having a larger area in contact with the edge of each to reduce the sparking. But although no emf , the pickup methods are so full of friction that ou is unlikely.
But great non the less, here is a small vid of a homopolar mounted in the chuck of my lathe. everything rotates together, 2 micowave magnets with a Ali disk..the faraday paradox
http://www.youtube.com/watch?v=75p5JwlXwlo
That video brings back memories. DePalma also showed me a demo of shorting the N-machine. I don't know if it proves anything though. You can also short a conventional faraday generator like that and it doesn't seem to slow down much that you can notice. The problem is that it's extremely difficult to get low resistance. Contact resistance can easily be 10 to 30 mOhm on stationary contact, and hundreds of milli ohms on a moving contact like that. Say 50mV output & 100mOhm = 0.025 watts.
@Craigy your results are surprising. Would you mind performing some extra experiments on that setup. Mainly increasing the radius of the current aluminum disc by atleast 2-3 times or using smaller magnets. What you want to measure is the voltage while each time brushing on a bigger radius on the disc. Start out very close to the magnet and take not of voltage, then gradually increase the radius. This should make the voltage go to 0, IF then at a slightly bigger radius the voltage reverses polarity then you have made an important discovery which I'll be happy to explain why. Could you try this out please.
Broli,
It appears Craigy's device is producing AC. Look how the readings from the volt meter jumps up and down the way it does. The polarity must be switching somewhere. If it is, then it's due to particle drift which I go into more detail below. All he needs to do is set his volt meter to AC, then test. I wonder if those magnets are radial magnetized.
I posted the below design in this thread a while back using a radial magnet, http://www.overunity.com/index.php?topic=5662.msg206989#msg206989
The blue disc is stationary and is not cutting the field, but the electrons flowing onto the blue disc from the red disc will cut the field of the south pole while moving towards the rim of the blue disc. I call this particle drift (The electrons cut the field, but the conductor doesn't). Brushes are needed to connect the inner and outer discs, but it allows you to spin a smaller mass, which requires less energy. So, the losses in the brushes and the energy saved in spinning a smaller mass probably negates each other. I have the inner disc to rotate, while the outer disc is stationary to produce a DC current.....but AC could be produced with both of them rotating together such as Craigy's device, assuming his magnet's are radially magnetized.
GB
In Craigy's device, the disc is larger than the magnets and is not totally contained within the magnetic field of the magnets. Wouldn't this cause eddy currents in the disc which could be responsible for the fluctuations in voltage?
GB
Quote from: gravityblock on December 12, 2009, 05:46:54 AM
In Craigy's device, the disc is larger than the magnets and is not totally contained within the magnetic field of the magnets. Wouldn't this cause eddy currents in the disc which could be responsible for the fluctuations in voltage?
GB
The lathe has current flowing through the rotor. I think I had the misfortune of being electrocuted by one once. I worked on them at one point, they're quite unpredictable.
AS a matter of fact, I think something should be done about that fact, they're quite dangerous at high speeds... the rotor is acting like an HPG, in fact.
No it only produces dc, the video was made in haste without thinking too much about the pickup points or brushes, i was just doing it to see the faraday parado
Half an hour after filming i fiddled some more by putting a wire to the tailstock of the lathe and could get almost 2 volts at 3000 rpm. I should have short circuited it , but didn´t. again used a bearing on the end of a probe for disc pickup.
I don´t have any more Ali , although the disc should really be copper but can´t get that here in the canaries.
Quote from: Craigy on December 12, 2009, 06:04:23 AM
No it only produces dc, the video was made in haste without thinking too much about the pickup points or brushes, i was just doing it to see the faraday parado
Half an hour after filming i fiddled some more by putting a wire to the tailstock of the lathe and could get almost 2 volts at 3000 rpm. I should have short circuited it , but didn´t. again used a bearing on the end of a probe for disc pickup.
I don´t have any more Ali , although the disc should really be copper but can´t get that here in the canaries.
You should check the rim of the rotor as well.
GB the point I'm trying to show is that there MIGHT be a polarity shift depending on where you measure. I attached an illustration of this below that should explain it. The question is if we keep on increasing the radius of the tapping point on the disc will there be a point of voltage reversal where the part of the disc going from the radius of the magnet to "infinity" overrules the voltage going from the center of the disc to the radius of the magnet...if so we can eliminate back torque. This can be easilly tried out with a setup like Craigy's with a sufficiently big disc plate a few times bigger than the magnet. I might perform this experiment as well with cardboard and tinfoil as my disc.
I tried another experiment where I routed a wire going from the outer edge of the PM going to the its center and then out. When high current was flowing through the wire, there was a force on the wire to force it to rotate, as expected, but there was *no* force on the magnet.
If the N-machine is COP>1, then it must be due to another effect. The current flowing through the metal does not produce a counter opposing force on the magnet.
This other effect might be due to the rotating magnetic field, as Bruce claims inertia changes (and perhaps other things) from rotating objects.
Paul
Quote from: gravityblock on December 12, 2009, 04:25:12 AM
It appears Craigy's device is producing AC.
Most of that is most likely due to contact voltages and the contact changing. If he would just place a 0.1ohm resistor across the voltage meter and make a lot better contact (perhaps from graphite brushes) then it would go away.
PL can you illustrate your latest experiment, I have a hard time understanding what you mean.
In the 1st experiment the current flowed through the NdFeB magnet from inner to outer edge. I wanted to do the same thing, except have the current separate from the magnet. So in the 2nd experiment the placed a wire that routes from the battery to the center of the magnet (perpendicular), then when the wire almost touches the magnet it routes parallel to the magnet to the magnets outer edge, and from there it goes to the batteries other terminal.
There was a rotational torque on the wire, but there was absolutely no rotational torque on the magnet.
So I think whatever N-machine effect there might be, it's something else other than what Bruce told me.
Paul
Does the below illustration show what you did? If so are you 100% positive the whole circuit if allows to rotate on a free axle rotates? This alone is something substational, I recommend you redo the experiment attaching the circuit to an axle so it can rotate.
I don't have the equipment to put it on an axle right now. My NdFeB magnet is not even 1" in diameter. Maybe a bit over 1/2" diameter.
BTW, anyone trying these experiments should use magnets with high coercivity such as NdFeB. Ceramic magnets due terrible when they're thin because of their low coercivity.
PaulLowrance,
If the magnet is fixed (such as being on the carpet), then the external circuit will rotate. If the circuit isn't attached to both the axis and the rim of the magnet, then there will be no rotation. Here's a few simple homopolar motors showing this.
http://www.youtube.com/watch?v=U9greHLiR5c&feature=related
http://www.youtube.com/watch?v=Xnxf1WeXxgk
GB
Quote from: gravityblock on December 12, 2009, 10:35:22 AM
PaulLowrance,
If the magnet is fixed (such as being on the carpet), then the external circuit will rotate. Here's a few simple homopolar motors showing this.
http://www.youtube.com/watch?v=U9greHLiR5c&feature=related (http://www.youtube.com/watch?v=U9greHLiR5c&feature=related)
http://www.youtube.com/watch?v=Xnxf1WeXxgk (http://www.youtube.com/watch?v=Xnxf1WeXxgk)
GB
No, that's not the experiment. The experiment is about getting the magnet to rotate, not the circuit.
Conventionally speaking, the magnet should not rotate.
I think the attention should be placed on Bruces inertia & gravity experiments where he demonstrated something very interesting happens to rotating objects. If the n-machine is cop>1, then maybe there's a change in the metal disc compared to the external wire circuit.
Quote from: PaulLowrance on December 12, 2009, 10:37:57 AM
No, that's not the experiment. The experiment is about getting the magnet to rotate, not the circuit.
The magnet isn't going to rotate if the outside circuit isn't attached to
both the axis and the rim of the magnet. You must have a force on both ends (the axis and the rim) before there is rotation. You're forgetting that the nickel coating on the magnet is the same as a disc glued to the magnet. If current doesn't flow through this nickel coating or the disc, then there is no torque on the magnet. Remove this nickel coating on the magnet, and you can spend a lifetime trying to get the magnet to rotate without success. Having a contact at the axis only, is the same as having no nickle coating or disc attached to the magnet.
GB
Both experiments proves there's no angular force on the magnet itself, which is in agreement with conventional physics. The force is on the electrical current.
I recall telling Bruce that the outer edge of his disc experienced 9000 G's centrifugal force. That's a lot of G's! IMO that's the secret. His large machines spun at over 10000 rpms. If the n-machine has a smaller diameter, then it should be made to spin at a higher rpm.
Twice the radius = twice the centrifugal force at the same rpm.
do you mean like this? not really sure
http://www.youtube.com/watch?v=3aPQqNt15-o
edit missed post above sorry
Quote from: PaulLowrance on December 12, 2009, 10:46:30 AM
Conventionally speaking, the magnet should not rotate.
Likewise, a magnet won't rotate if there is no current flowing through a coil in regular induction. The disc or conductive coating is similar to a coil. If only one lead is attached to the conductive coating, then it's like only having one lead connected to a coil.
Your experiment proves nothing because it is doing nothing. Try to get a magnet to move with only one lead connected to a coil. It's not going to happen. You must have a force on both ends (the axis and rim) just like having both leads connected to a coil.
GB
Quote from: gravityblock on December 12, 2009, 11:09:26 AM
Likewise, a magnet won't rotate if there is no current flowing through a coil in regular induction. The disc or conductive coating is similar to a coil. If only one lead is attached to the conductive coating, then it's like only having one lead connected to a coil.
You're experiment proves nothing cause it is doing nothing.
First one proves the magnet does not produce an opposing force, which is the magnet & the current flowing through it rotated.
Second one proves that the current itself does not cause the magnet to rotate.
Quote from: Craigy on December 12, 2009, 11:08:46 AM
do you mean like this? not really sure
http://www.youtube.com/watch?v=3aPQqNt15-o (http://www.youtube.com/watch?v=3aPQqNt15-o)
edit missed post above sorry
No, current is flowing through the magnet in that one.
My 1st experiment was conclusive, but the 2nd one was not since it's more difficult to perform. maybe someone else could do it with bearings & on an axis.
Quote from: Craigy on December 11, 2009, 08:37:46 PM
I have played with homopolars, they really are cool and mystifying. No back emf at all, But their greatest downfall is the contacts with rim of the disc...
Hw about the rim rotating through a shallow trough of mercury.
Or: have two homopolar discs meshing like gears, and take the current
from the two shafts.
Quote from: PaulLowrance on December 12, 2009, 11:26:18 AM
My 1st experiment was conclusive, but the 2nd one was not since it's more difficult to perform. maybe someone else could do it with bearings & on an axis.
Try to get a magnet to move with only one lead connected to a coil, because it's the same thing as only having one lead connected to the conductive coating on the magnet. The results are the same. No current flowing through the conductive coating or the coil, then no movement of the magnet.
Quote from: Paul-R on December 12, 2009, 11:28:52 AM
Hw about the rim rotating through a shallow trough of mercury.
Or: have two homopolar discs meshing like gears, and take the current
from the two shafts.
There is no need in having brushes at the rim or to have meshing gears with the correct setup. This allows you to extract the current with a slip ring at the axis on both sides of the magnet. Again, I must stress, with the correct setup. The correct setup also increases the voltage. In fact, it may be possible to have a brushless system, but it hasn't been tested or confirmed yet.
GB
Has anyone ever got an n-machine to self-run?
Quote from: PaulLowrance on December 12, 2009, 12:04:46 PM
Has anyone ever got an n-machine to self-run?
In figure 2 of the below link, it should self-run, but it has a design flaw by not allowing the outside circuit to pass the horseshoe "C" magnet. This is based on "M" hypothesis and not "N" hypothesis.
http://www.andrijar.com/dcmachines/index.html
Here's more details about the final test, http://www.andrijar.com/fte/index.html
I did another experiment, same as experiment #2, this time using a spherical magnet, about 1" diameter, that's polarized in a similar fashion as the Earth. This provides low friction since it's sitting on a point. Also a lot more current was pumped into the external circuit. So again, this experiment is to test if the electrical current can cause the magnetic material itself to rotate. Again, the electrical current does not flow through the magnet in this experiment. The electrical current flows through metal that is not bonded to or touching the magnet. In this experiment the *entire* magnet wanted to move in a single direction, which is the same results as my experiment #2 using the disc NdFeB magnet. I saw no rotation.
Again it's difficult to say for experiment #2, since it's not fixed on an axis.
PaulLowrance,
Please keep us informed of your experiments. Experimentation can always lead to unexpected results that could be beneficial.
Thanks for sharing,
GB
Hi GB,
Are these pages yours?
http://www.google.com/search?q=DYNAMO+site%3Awww.andrijar.com (http://www.google.com/search?q=DYNAMO+site%3Awww.andrijar.com)
Those pages are not mine. There is a lot of informative information contained within those pages. What do you think about them?
Quote from: gravityblock on December 12, 2009, 01:56:53 PM
Those pages are not mine. There is a lot of informative information contained within those pages. What do you think about them?
They seem interesting, but haven't studied them that much yet.
Here's an old experiment that I've wanted to do for ages. If it's already done, then please let me know. Experiment: Place a very long straight wire starting from the outer edge of disc magnet and going outward several feet or more. The wire never touches the magnet. At ~ 1/2 to 1 foot away from the magnet, cut the wire in two, and connect both wires to an electrometer. Then spin the magnet. I want to know if the electrometer shows a DC voltage. If there is, then there's an E-field.
From what I've read, there is a static electric field when current isn't being taken off the disc/magnet when they're rotating together. If you were rotating with this disc/magnet, you're meter would read a voltage potential.....but this voltage isn't able to be brought out of the system due to no return path.
The external circuit provides the return path, but if it is also rotating with the disc/magnet, then it will have the same polarity as the disc, thus current can't flow. The external circuit when rotating with the disc is just part of the disc and will have an electric field pointing in the same direction as the disc.
Relative motion between the disc and external circuit creates a return path for current to flow due to the EMF on the external circuit is pointing in the opposite direction as the disc. Increasing the relative motion will increase the voltage.
Relative motion between the disc and outside circuit isn't required to have current to flow. There are other ways, at least in theory.
Quote from: broli on December 12, 2009, 10:17:21 AM
Does the below illustration show what you did? If so are you 100% positive the whole circuit if allows to rotate on a free axle rotates? This alone is something substational, I recommend you redo the experiment attaching the circuit to an axle so it can rotate.
Ok can try that tomorrow , i have some 21 mm x 16.3 x 6 n 35 rings, that i can cap with steel washers to increase the pole face over the whole of the 21 mm dia, then true it all on a shaft on the lathe and mount it on some nasa bearings, although it will need a little current limiting. I can't see it working but cannot harm to try
I tried this, as pictured, and it does not spin on the wire axis.
Can someone tell me why it doesn't even budge?... perhaps I'm going about the oppositional field in the wrong way?
On second thought, this might work if I were to place two magnets N to N?
Or..more testing due I suppose.
I'm just looking for a variant setup to further the demonstration.
Could you post a bigger picture, all I see is a twisted wire and what seems to be a screw in the middle.
Quote from: broli on December 12, 2009, 05:24:44 PM
Could you post a bigger picture, all I see is a twisted wire and what seems to be a screw in the middle.
I'm not sure how you interpret that from the picture...But I'm trying another setup now, it seems more in-line than the previous attempt.
The currents causes cancellation in the torques.... perhaps this next attempt will overcome this.
EDIT: update: ... I tried another setup, ..it flinches, perhaps a flinch motor, doesn't spin though, I need a more rigid setup really, I do notice it reacting to the current, but only a little bit.