Fleming's "right hand rule" is not working for me. Why?

  • Electrical
  • Thread starter MDG
  • Start date
  • #1
MDG
8
0
I built this DIY generator on the thought that the flux from two north poles of a magnet would be attracted to an iron core of a toroid coil. I wrapped the 4 inch OD toroidal coil with about 700 turns of 27 awg wire. The toroid coil is stationary with the magnetic flux rotating around the coil. I've only been able to produce about 500 millivolts with it being very erratic. DC in one direction for 1 second then the other direction for a second or two. Switched the voltmeter over to AC and I get a reading of 400 to 500 millivolts. I don't know why it doesn't work. According to "Fleming's right hand rule" it should...but doesn't. I'm attaching a simple drawing showing the principal of it. I must be violating some law of physics so if anybody here could point it out I would appreciate it. It's driving me crazy.
Toroid Coil jpeg resize.jpg
 

Attachments

  • center coil 1 jpeg.jpg
    center coil 1 jpeg.jpg
    38.6 KB · Views: 12

Answers and Replies

  • #2
Baluncore
Science Advisor
8,969
3,551
Welcome to PF.
The circular magnetic field inside the toroid is generated by the external winding. The magnetic fields outside the toroid cancel.

It is only the one loop of the helix coil around the toroid that generates an axial magnetic field. If you feed one connection back round the toroid, even that will disappear.
 
  • #3
MDG
8
0
Thanks very much! I needed an answer. It was driving me crazy. So I'm understanding from this that a toroid coil would not work for generation but only transformer application. Another thing that I didn't mention was that I also tried this with north field on one side of the toroid and south on the other & rotated each in opposite directions still complying with Fleming's rule but with the same result.
Again thanks so much! I have some other ideas to move on to without a toroidal coil.
Thanks,
Mike
 
  • #4
MDG
8
0
I built this DIY generator on the thought that the flux from two north poles of a magnet would be attracted to an iron core of a toroid coil. I wrapped the 4 inch OD toroidal coil with about 700 turns of 27 awg wire. The toroid coil is stationary with the magnetic flux rotating around the coil. I've only been able to produce about 500 millivolts with it being very erratic. DC in one direction for 1 second then the other direction for a second or two. Switched the voltmeter over to AC and I get a reading of 400 to 500 millivolts. I don't know why it doesn't work. According to "Fleming's right hand rule" it should...but doesn't. I'm attaching a simple drawing showing the principal of it. I must be violating some law of physics so if anybody here could point it out I would appreciate it. It's driving me crazy. View attachment 281506
I’ve been giving this more thought and I understand that a toroid coil locks the flux inside the coil. In the illustration I have a “N” pole on each side of the coil. I believe the magnetic dipoles inside the toroid coil realign themselves with “S” poles attracted to the two external “N” poles with opposing “N” poles in the center of the core. It seems like this would create DC without brushes or slip rings. In the lower left corner you can see the setup. As I said in the first post I was only able to produce erratic AC and DC at 500 millivolts. I have since purchased a galvanometer to get a better idea of what is happening in slower time. Starting from the top of the coil (position of leads) I moved a single magnet counter clock wise producing 2 to 3 millivolts negative until I reached the half way position on the coil (180 degrees). It then reversed to 2 to 3 millivolts positive until I reached the top again. This explains the AC reading but doesn’t tell me why. The coil is wrapped completely in one direction. It is NOT a bucking coil.
 
  • #5
Baluncore
Science Advisor
8,969
3,551
Where the two N poles face each other their fields tend to cancel. If the field is cut by the coil then it must exit the core above and below, cancelling.

You need to draw each closed magnetic field line with arrows, from the N pole to the S pole, so you can see where the two separate magnetic fields will sum, and where they will cancel.

Unfortunately, you cannot generate DC without a slip-ring, a commutator, or a rectifier.
 
  • #6
MDG
8
0
Where the two N poles face each other their fields tend to cancel. If the field is cut by the coil then it must exit the core above and below, cancelling.

You need to draw each closed magnetic field line with arrows, from the N pole to the S pole, so you can see where the two separate magnetic fields will sum, and where they will cancel.

Unfortunately, you cannot generate DC without a slip-ring, a commutator, or a rectifier.
I see now that it is as important that the magnetic circuit be complete (or closed) as is the electrical circuit. Mother Nature is very hard to fool. I still don't understand why I get a couple millivolts potential in one direction starting from the leads of the coil and then a couple millivolts potential in the opposite direction at exactly 180 degrees on the coil? I move the magnet at about 1 inch increments and watch the galvanometer deflect negative 1/2 cycle then positive the other 1/2 cycle. It's a 4 inch diameter coil so the flux is not spilling over from the 5/8 x 1/4 inch magnet.
 
  • #7
Baluncore
Science Advisor
8,969
3,551
There are so many variables undefined, or that may have changed in your experiment, that I have no idea what you are really doing. There are three possible axes that you can rotate something 180° about. In which direction are you moving the magnet? Which magnet?

When you write "The coil is wrapped completely in one direction. It is NOT a bucking coil." I have to wonder if it is a simple helical winding on a toroidal core, with the leads running parallel. If that is the case then it is actually a one turn coil the size of the toroid, which might explain the few mV you are seeing.

You need to do simple experiments until you can predict correctly what will happen. Even then you will find things that do not at first appear to be rational.
https://en.wikipedia.org/wiki/Faraday_paradox
 
  • #8
MDG
8
0
There are so many variables undefined, or that may have changed in your experiment, that I have no idea what you are really doing. There are three possible axes that you can rotate something 180° about. In which direction are you moving the magnet? Which magnet?

When you write "The coil is wrapped completely in one direction. It is NOT a bucking coil." I have to wonder if it is a simple helical winding on a toroidal core, with the leads running parallel. If that is the case then it is actually a one turn coil the size of the toroid, which might explain the few mV you are seeing.

You need to do simple experiments until you can predict correctly what will happen. Even then you will find things that do not at first appear to be rational.
https://en.wikipedia.org/wiki/Faraday_paradox
I’ve attached another illustration to hopefully better explain where I’m at in this & what I am doing. As I said earlier I am using a 5/8” X ¼” single magnet and rotating it in a counter clock wise direction. I failed to mention I was holding the magnet in my hand & also that it is an N52 neodymium magnet. I didn’t want to mechanically power the original configuration with 26 of these N52 magnets as I was getting 400 to 500 millivolts and would have blown out the galvanometer. Sorry about mentioning that it wasn’t a “bucking coil”. I had read that a “bucking coil” were two separately wound coils on the same core that opposed each other. Maybe they’re only used in transformers but I added that information so that you or anybody else reading this would know it was not & not the reason for the AC output. Yes, it is an helical coil with 700 ampere turns of 27 awg wire. As far as rotating around the axis, I was meaning the face of the toroid coil. Maybe that’s the “Y” axis, I don’t know. I do know that it’s not the top or the inside of the toroid coil so if it was a tire I would call it the sidewall. I followed the link you provided for information on Faraday’s Paradox. I spent hours reading about it and the theories offered. Seems the theory that the magnet was contaminating the brushes, wire and equipment is what stands. I thought that was the answer to my problem but rechecked today & moved the magnet all around the leads and equipment with only the slightest vibration showing on the galvanometer. What I did do differently today was to not rest the magnet on the face of the coil & push it an inch at a time. I held it about ½” off the coil and rotated it around the face. The illustration gives all the details. Thank you for your time & thought, Mike
 

Attachments

  • Experiment 2.jpg
    Experiment 2.jpg
    73.8 KB · Views: 4
  • #9
Baluncore
Science Advisor
8,969
3,551
@MDG You are kidding yourself that you have 700 turns on the toroidal former, being influenced by the external magnet. Believe it or not, you actually have only one turn, hence the very small signal.

The internal flux of your 700 turns is not completely confined to the core. That is because you fail to counter-wind one terminal wire back around the core to cancel the one turn of the coil axis about the circumference of the toroid.

Look very closely at fig 4 and fig 5. Do you notice the white counter turn?
https://en.wikipedia.org/wiki/Toroi...for_total_internal_confinement_of_the_B_field
 
  • Like
Likes sophiecentaur
  • #10
MDG
8
0
Yes, I misspoke when I described the 700 turns on the toroid coil as ampere turns. At this point they are just turns. You said it was only one turn. I’m guessing you meant one simple helical coil? As far as the amp turns aren’t they yet to be determined. A 6 volt lantern battery can supply 6 ah. 1 amp per hour for 6 hours. Doesn’t seem like such an unrealistic goal to produce as many amps as a lantern battery. 1 amp X 700 turns = 700 ampere turns. Actually aren’t all the potentials (amps, volts, wattage) yet to be determined? Not with this configuration but will keep working on the flux / magnetic circuit failure. At this point I’m just trying to figure out the reversing voltage in the coil. Maybe it has to do with the flux leakage. I followed the link you gave me to the page describing flux leakage of toroidac coils and the fix with the second wire. I was interested in fig.4 or fig.7 (not sure). It showed a toroid core with helical coil and no second wire. It gave positive values for ½ of the coil & negative values for the other half. I’m not sure what it represented but was exactly the same thing as my coil is doing. If I connect to one of the terminal wires and back wrap around the coil to the other lead to cancel the flux wouldn’t that also cancel any potential current? Well I guess it’s all mute now with this coil without being able to complete the magnetic circuit.
 
  • #11
MDG
8
0
One more quick thought. When I went to the articles on Faraday’s Paradox some of the authors addressed the properties of cylinder magnets and the flux. I originally wanted to use ring magnets on the toroid coil but I couldn’t decide if the lines of force are locked into the magnet or would slip and remain stationary while the magnet rotated. This was also of concern to them in attempting to solve the paradox. I think the latest study in the articles was done in 1998. They reached the conclusion that the flux rotated with the cylinder. Do you know if that still holds?
 
  • #12
Baluncore
Science Advisor
8,969
3,551
Yes, I misspoke when I described the 700 turns on the toroid coil as ampere turns. At this point they are just turns. You said it was only one turn. I’m guessing you meant one simple helical coil? As far as the amp turns aren’t they yet to be determined.
You are still missing the critical point. Amp·turns are irrelevant and distracting.

The 700 turn winding has almost no external field. The flux is almost all internal. The EXTERNAL magnet is NOT coupled to the toroid's INTERNAL flux path.

Why “almost all” and not “total” ? Because the axis of the coil is effectively one circumferential turn around the outside of the toroid. A “counter turn” cancels that axial turn and totally confines the flux to the toroidal core.

You are seeing only the effect of the magnet on that one external turn.
Go back and study the section of the wikipedia article.
Look very closely at fig 4 and fig 5. Do you notice the white counter turn?
https://en.wikipedia.org/wiki/Toroi...for_total_internal_confinement_of_the_B_field
 
  • #13
MDG
8
0
You are still missing the critical point. Amp·turns are irrelevant and distracting.

The 700 turn winding has almost no external field. The flux is almost all internal. The EXTERNAL magnet is NOT coupled to the toroid's INTERNAL flux path.

Why “almost all” and not “total” ? Because the axis of the coil is effectively one circumferential turn around the outside of the toroid. A “counter turn” cancels that axial turn and totally confines the flux to the toroidal core.

You are seeing only the effect of the magnet on that one external turn.
Go back and study the section of the wikipedia article.
I will go back to the wikipedia article and anything else I can find. Will check Amazon tonight for books on the fundamentals of electricity, magnetism and what ever else is related. I realize now that this is way over my head but I can't stop thinking about the subject.
 

Related Threads on Fleming's "right hand rule" is not working for me. Why?

Top