Is Earth's Magnetic Field Affecting My Homemade Compass?

[Robin07]

I've made a possible compass?

I've fashioned a rotating permanent magnet rotor with four poles, like poles are opposite to each other. I made this to take advantage of the gyroscopic effect that would be realized at various rpms. The rotor is being pulsed by a DC pulse-coil to start and aid in its rotational momentum. This has worked well as per design. What I didn't anticipate was that the rotation of the rotor would start to slow down and reverses when and only when its rotated from its starting point @~<360 degrees. This revving up and reversing oscillation continues until you disconnect the power. This is not what I had expected. Please do take note that the current path is through the center rotor shaft. This I understand to contribute to rotation as well.

The reason I'm posting this in Earth Siences is that I suspect that this mechanism is orienting itself to our/Earths magnetic field. Is this even possible? Short of me taking readings on various spots around the globe.

Thanks for your responses in advance
Robin

 

[Bobbywhy]

I've fashioned a rotating permanent magnet rotor with four poles, like poles are opposite to each other. I made this to take advantage of the gyroscopic effect that would be realized at various rpms. The rotor is being pulsed by a DC pulse-coil to start and aid in its rotational momentum. This has worked well as per design. What I didn't anticipate was that the rotation of the rotor would start to slow down and reverses when and only when its rotated from its starting point @~<360 degrees. This revving up and reversing oscillation continues until you disconnect the power. This is not what I had expected. Please do take note that the current path is through the center rotor shaft. This I understand to contribute to rotation as well.

The reason I'm posting this in Earth Siences is that I suspect that this mechanism is orienting itself to our/Earths magnetic field. Is this even possible? Short of me taking readings on various spots around the globe.

Thanks for your responses in advance
Robin

I am having a difficult time understanding your rotor configuration. Can you post a diagram? Also, will you please describe the slowdown and reversing oscillation? Either I cannot understand English so well or it is ambigous.
Thank you,
Bobbywhy

 

[Robin07]

See if this helps, imagine a ball cut in half. We're only dealing with the lower 1/2 of the hemisphere. This hemisphere is actually a single layer bifilair wind of magnet wire c/w a diode. This design makes for a weak equatoral electromagnetic flux field, since the wind, at that point is 100mm in diameter. The southern most region has a very strong field opposite to the equatoral perimitere region. This southern region is very strong because the winds are much closer leaving an air core, single layer hole, of 12mm in diameter. The magnetic rotors' shaft/axis is housed slightly above and runs parrallel with the equatoral perimiter. The axis is free to rotate in a horizoltal plane around an equatorial track/ring, while the rotor spins in a vertical plane, perpendicular to the axis as well as always being tangental to the winding. This coil should have a very similar electromagnetic flux field to a soleniod, meaning that the poles are located primarily on either end on the coil. The repeaded speeding up, reversing to start again approx 360 degrees from its' starting point tells me that the coils' flux field, North/South is located not in a vertical plane but in a horizontal plane. And that just doesn't make sense. So how is it that the rotor is being oscilated in this unpredictable manner?

If you should need a picture I'll try but I'm not very savy in this regard. I understand that this is an unususl coil design. I chose it because it gives me the strongest field for he amount of wire being used. This design also has very little reluctance hence it doesn't heat up. The industry, if I understand it correctly use this type of coil in MRI machines.

 

[Bobbywhy]

Robin07, I am interested in your experiment but I can’t visualize your experimental setup yet...even with your second explanation. A diagram or photo would sure help a lot. Meanwhile, I have divided your explanatory paragraph into its eleven separate sentences to ask you for detailed clarification.

1. “See if this helps, imagine a ball cut in half.”
That I understand.

2. “We're only dealing with the lower 1/2 of the hemisphere.”
Do you really mean “the lower ½ of the hemisphere” = one quarter sphere?

3. “This hemisphere is actually a single layer bifilair wind of magnet wire c/w a diode.”
Does the bifilar winding have a hemispherical shape? How is it wound? What does “c/w a diode” mean? How is the diode connected? Is it possible you mean this, shaped into a hemisphere?: http://en.wikipedia.org/wiki/File:TeslaBifilar.png

4. "This design makes for a weak equatoral electromagnetic flux field, since the wind, at that point is 100mm in diameter."
What is 100mm in diameter and at what point?

Are you trying to build a rotating-coil magnetometer ?

Will you please respond to these questions? As for the remaining sentences in your description, I will wait for your responses to these, please.

You also stated: “I understand that this is an unususl coil design. I chose it because it gives me the strongest field for he amount of wire being used. This design also has very little reluctance hence it doesn't heat up.”
This confuses me because reluctance does not dissipate electric energy like electrical resistance does. It stores magnetic energy: a magnetic field causes magnetic flux to follow the path of least magnetic reluctance. So the coil would not heat up even if it had a high reluctance.

Cheers,
Bobbywhy

 

[Robin07]

1. Ok we're in sink imagining a ball cut in half.”

2. I ment 1/2 sphere or one hemisphere but not one quartar of a sphere. The lower half of
a ball.

3. Yes the bifilar winding has a hemispherical shape. The coil is wound parrallel to what would be the equatorial line around a ball/sphere. c/w means 'complete with' and the diode is connected in series between the return wind in the bifilair connection, and yes its very much like The Tesla pancake coil, but bowl shaped. It's quite literaley can float on water, bouant like a boat.

4. What is 100mm apart is the actual winding around the equatorial region. Where the ball is cut in half is 50mm in radius/100mm apart. At the lower end of the coil the radius of the hole/air core is only 6mm in radius. Like a funnel wider at the top and narrow at the bottom.

No I'm not trying to make anything that indicates strength or direction of gauss/flux/ or magnetic fields. I simply asked because I may have inadvertantly be making one, What I am trying to make is a new form of locomotion, but at this time I'm just dealing with the motor. we can get into that at a later time.

An third year electrictian told me the reason it doesn't heat up was of its low reluctance. I was simply repeating. In any event it doesn't heat up. He also said that this coil is an inductor. He couldn't explain or give advice with my issue, hence this physics forum. And he saw this mechanism work.

 

[davenn]

OK we got and understand the lower 1/2 of a sphere part
the rest of everything is still pretty vague. is this unit got voltage supplied to it ?

we really really need a photo so that we all can see what you are trying to do :)

cheers
Dave

 

[Robin07]

Ok, I'll need to put it all back together today inorder to upload a pic. Or would a vid be better. Now that I say that, I don't think vids are allowed in this forum. Do you know anyone that is willing to FEMM this for us?

 

[Robin07]

OK we got and understand the lower 1/2 of a sphere part
the rest of everything is still pretty vague. is this unit got voltage supplied to it ?

we really really need a photo so that we all can see what you are trying to do :)

cheers
Dave

Yes the power used at this time is an AC/DC standard, variable DC voltage transformer you can pick up at you local electronics store. 120VAC to 9VDC. I'm using 9V.

Do you know anyone that is willing to FEMM this? In this way we all can be more clear.

Thanks

 

[Robin07]

In the mean time look up Newman motor. My setup is very similar, but mine uses a hemisphere bifiliar wound coil underneath the rotor and most the important difference is that my axil is not fixed. Its free floating to be able to follow a track around, inside the cylindercal housing perpendicular to the rotors vertical rotation. This adaptation is from a gyroscope wrist exerciser a Dynbee or Powerball. Imagine a powerball with a magnetic essembley/rotor and a single layer hemisphere coil as the trigger to get the weight/rotor turning. I'm able to get this sucker/the rotor spinning at 3200 and faster pending the voltage supply. It gets scary fast. At certain points I need to switch it down to only 3 volts. But like I said, it will only truns 360 degrees, in the track, then return in reverse fashion.

In an earlier model I didn't have the current running through the shaft. The rotor and shaft essembly were electricly isolated. But this would have a worse effect... It now only traced a 90 degree back and forth pattern, regardless of its starting point. So I re-hooked up the current to the track, in series, and now I have the essembley do the 360 degree ossicaltion repeating pattern thing again.

 

[berkeman]

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