Rotating Magnetic Field's and Inductors.

[woopy]

OK-just finished the test with the ring magnet on a string--cotton thread used for sewing.

I started with the magnet 2mm off the wooden floor. When started,the magnet once again(as all the other test done showed)spun in a CCW direction. After 7 minutes the magnet touched the floor.
Two things tell us that it is the string/thread unwinding.
1- All thread around the world(or most there off) is wound in the same direction--something to do with a world standard,so as it suits all sewing machines around the world,and the way the bobins spin in those machines. I guess if it was wound in the opposite direction,the spin direction of the bobins in sewing machines may unwind the thread?.
Anyway,this is why we all get the same CCW spin,no matter where in the world we are.
2- The simple fact that my thread got longer,and not shorter,is telling us that the thread is unwinding.

Ah well,it was a quick,easy and fun test,and as far as i can see--problem solved.


Brad

Thank's very much Brad for testing it

And also Luc and Jim and others.

So effectively "problem solved"

I have made a video (with comments ) of some testing i did as i have the matos to do it.

https://youtu.be/HBNrPubeGVc

Effectively with a  unidirectional non twisted kevlar string, the tendency to have more CCW movement is confirmed in my particular house,  and it is also possible to get some turns of CCW rotation (probably due to initial input), but nothing so spectacular as with the cotton sewing  thread.

It is anyway interesting to play with so simple experiment to better feel with once fingers ,the earth magnetic field. I did not imagine before, that it could be so strong.

Hope not having disturbed the thread too much

Laurent

[MileHigh]

Brad:

>>> Magluvin referenced a book where a a coil with a ferrite core can be "preloaded" under the influence of an external magnetic field.  Considering in my example the two magnetic fields are 180 degrees diametrically opposed I think that will apply in this case.  It looks like when the coil first energizes it has to do the work to "clear out" the biasing of the core which is in the opposite direction that the coil wants to fire.  That sounds to me like it will increase the effective inductance - in this case.

Lol-amazing . Here i have been,trying to tell you this on two thread's !!for how long now!!?,and all i get from you and Poynt ,is that is incorrect.

I am talking about the simple controlled test that I described in my posting.  It's separate and distinct from your pulse motor so why are you making a connection when there is no connection?

Beyond that, I don't get that feeling or remember statements like that from you.  If you can show me where you said that that would be appreciated.

>>> On the other hand, if a static and unmoving magnet was "behind" the coil and biasing the core in the "right" direction, then when the coil was energized then in short order the core would get saturated and go "air core."  That sounds like it would reduce the effective inductance to me.  See?  You actually have to think these things through.

!!We!! have to thinks things through (http://overunity.com/Smileys/default/rolleyes.gif)-->man,where have you been for the last two week's-->and what have myself and Luc been trying to tell you??.
We have to think things through Lol--is this some sort of joke MH?.

One more time, I am talking about the simple controlled test that I described in my posting.  It's separate and distinct from your pulse motor so why are you making a connection when there is no connection?

One more time, please go ahead and show me what you have been telling me.  Or are you just saying something for the sake of saying something with no context?

I assume that your frame of reference is your clips where you narrowed the pulse from the signal generator as much as possible so that the rotor was still turning.  This was done with your lossy coil.   I will just repeat again that has nothing to do with the controlled test that I described in my posting:

<<<<<<<<<<<<<<<<<<<<<<<,
For how it's happening, a simple test that anybody can do:

Suppose you pulse a fixed coil and it produces a north field that is facing the north end of a movable magnet:   

[S-coil-N]   [N-magnet-S]

So naturally the magnet will get pushed away when you pulse the coil.

Now, what happens if you have the coil open circuited and on your scope, and you pull the magnet away?

My expectation is that you will see an EMF generated by the coil that is opposite the applied voltage of the battery that you used in the first part of the test.

The conclusion:  When the battery pulses the coil, and the magnet gets pushed away, then the moving magnet will induce EMF in the coil that effectively reduces the voltage applied across the coil.  Even though you can't see it on your scope, it's still happening "inside" the coil.  That internal EMF opposing the battery voltage will reduce the rate of current rise when you energize the coil.  WOW - two things are happening simultaneously inside the coil.
>>>>>>>>>>>>>>>>>>>>>>>>>>>

So I would say that all the righteous indignation is misplaced and saying, "That's what I have been saying to you all along" is not even applicable considering we are discussing two separate things.   Nor can I recall cases where you say what you are alleging you said.   Lots of postings have passed under the bridge, so if you want to cite specific examples I will try to respond.

MileHigh

[MileHigh]

Brad:

>>> 2.1) When the magnet moves away, an EMF will be induced in the coil that is opposite that of the battery.

Not with my DUT,as it is the south field that is approaching the core of the coil that produces a north field at the end of the coil where the rotor is. But this has nothing to do with the reduction in current on the P/in side.--Detailed reason and evidence at bottom of this post--that you seem'd to have overlooked.

Yeah, but I am talking about my proposed controlled test, and not about your pulse motor.  Do you get it?  The bait and switch and moving the goal posts games you play to advance your argument are too much sometimes.

As far as your motor goes, the first issue for me is that your eight-pole rotor relative to the large coil gives you a blended magnetic polarity as viewed by the coil.   There is no "heartbeat, inverse heartbeat, heartbeat, ..." waveform associated with alternating north and south outward facing poles on the rotor.  There is what looks like a modified sine wave with a more half-circular form to the positive and negative excursions.  So to me that makes it unclear as to what a "south field that is approaching the core" really means.  The rotor is spinning slaved to an outside signal source.

What your motor needs if you want to analyze it properly is a timing diagram that you mark up and improve as you continue your investigations.  For example, the rotor is spinning slaved to the pulse train from your signal generator.  Do you know if the motor is spinning due to attraction pulses or repulsion pulses?   From my perspective, I don't really know.  I am not even sure if you really know.  If that's the case, how are you supposed to truly understand the dynamics of your motor and the drive coil if you still haven't pinned down the basic timing?

I would love it if you actually made a timing diagram and said things like, "Relative to our zero reference angle the pulse starts at 40 degrees and ends at 65 degrees and it is operating in attraction mode.  I am not expecting you to do it though, so it makes it that much harder to figure out the coil dynamics for your operating pulse motor.

My recommendation to you is if you intend to start out fresh with a new setup with a new more efficient coil, etc, then work on a timing diagram from the get-go.  You will see how much easier and clearer things are like that.  For a modest extra effort you get a big bang in returns.

MileHigh

[MileHigh]

Brad:

>>> 2.2) It's likely that the summation (integration) of the  "negative EMF" times the instantaneous current flow represents the energy that is put into the moving mass of the magnet - the motor action.

So once again we are being told that energy from the coil is transferred to the rotor,and at the same time the rotor returns this stored energy,!!BUT!! the I/ in drop's resulting in less P/in. Once again-some how,we have put energy into the rotor,and taken that energy back out(equal and opposite-minus losses due to windage and bearing friction of the rotor),but seem to have reduced the P/in

Yes, for sure energy is being transferred from the coil to the rotor and a few people have floated the suggestion that the rotor also returns the stored energy.  From previous postings you rejected this.  That shows you failing to think past one or two steps.  Let's say the coil is energized from 20 degrees to 70 degrees.  It's just a hypothetical.  From 20 degrees to 50 degrees the coil can be putting energy into the rotor.  From 50 degrees to 70 degrees the rotor can be returning energy to the coil.  It's possible, but you never thought about it that way and simply blocked out just the idea of it in your mind.  And since we have no timing diagram at all, we are just guessing.

Yes, the average input current can drop and the average power in can drop.  We have reduced the average input power.  You seem to think that is a radical concept, like it's breaking a "rule" or something.   One more time, you are forgetting that with no rotor and higher input power - the input power is nothing more than useless waste heat.  With no rotor the coil is a just a glorified resistor.  So there is no "big deal" to go from 100% waste heat at a higher average input power to 40% mechanical output power and 60% waste heat at a lower average input power.  No rules have been broken - you changed the configuration and when you did that change you are changing the overall electro-mechanical impedance of the system.  You seem to be forgetting about the waste again.  This has been discussed many times already.

We have reduced the power-in when we added the rotor and it means nothing.

MileHigh

[poynt99]

Is the information and test results not enough to confirm this?

While you may believe your hypothesis to be true, you have not demonstrated results that verify that hypothesis.