The bifilar pancake coil at its resonant frequency

[TinselKoala]

Ok,  i see what you mean,  no i just sweep from one side to the other in a straight line.
When doing it your way, i have the most strength in the center at the hole, not at the edges.

Sure, because the field lines "bunch up" near the center hole, but must spread out around the edge. Just like winding a toroid with wire: the wire is close together and bunches up in the center hole but spreads out at the outside. There are the same "number" of lines at center and at edge, so they must be further apart at the edge, resulting in a lower field strength across the area of the sensor (fewer lines cross the sensor plane, flux density is less).

If you can combine the drawing from post #1014  (http://overunity.com/17186/the-bifilar-pancake-coil-at-its-resonant-frequency/msg504697/#msg504697) with the below
one, you might get the picture.


Itsu

The colors are wrong and should be removed.

Coloring the side view that way implies that the Top view looks like this:  But I hope it is obvious that this "color assignment"  is incorrect.

[itsu]

Off course that can not be correct, but still my hall sensor detects opposite fields when skimming the surface of the disk from left to right or top to bottom.

I think how MH have explained it is correct.

Itsu

[TinselKoala]

@Tinselkoala,

Here's another Amos and Andy explanation below:


"The "negative" sign on your ammeters is there to show you which way the current is flowing, not to indicate the existence of your imaginary current".

Negative current is positive current moving backwards.

You admit to switching current direction, but you object to calling the reversal a reversal of polarity.

Someday, if you live long enough, you might learn to stop misrepresenting and redefining what others say, but I doubt it.

Current has no polarity. Voltage has _relative_ polarity. Current is the flow of charge and always flows from higher potential to lower potential.

You are getting all twisted up with yourself, you can't even get your own definitions to be consistent.


And I note, and preserve for the record, the further childish insult contained in your post.  How is your personal vendetta against me coming along? 

[TinselKoala]

Off course that can not be correct, but still my hall sensor detects opposite fields when skimming the surface of the disk from left to right or top to bottom.

I think how MH have explained it is correct.

Itsu

Yes, it is, and if you do the test I recommended, scanning all around the edge of the coil with the hall sensor in the plane of the coil, you will see no opposite fields, the lines will always go through the sensor in the same direction.

[Magluvin]

Off course that can not be correct, but still my hall sensor detects opposite fields when skimming the surface of the disk from left to right or top to bottom.

I think how MH have explained it is correct.

Itsu

Well if you face the hall inline with the fields as he has shown you should have higher flux readings than you have observed because the hall is still facing left and right when you bring it around the outer edge. So in my example imagine starting at the top where it says North in your drawing and as you move to the left toward the outer edge of the coil, the hall should be rotated as you move it so that by the time you are at the outer edge the hall will have turned 90deg, and then another 90deg once it is on the South marked side below.  If you can, try it and see if the outer edge is stronger than if it was with the hall the way you did it before. Just for giggles.

I will be doing the same tests but as I have described

Mags