Advanced and Delayed magnetic field's.

[TinselKoala]

Hi Brad
A point I forgot to mention: Could you please test the current draw of the rotor motor with and without a slight mechanical load? That is, let it run freely as in your video, show the draw, then put a slight drag on the rotor with a fingertip or suchlike, and show the current draw in that condition?
Thanks--
--TK

[MarkE]

This thread is about advanced and delayed magnetic field's-no lenz delay PLEASE
Below is a video of a generator that uses two ferrite C core's to form the complete ferrite core assembly. As you will see in the video,the secondary coil recieves most(about99%)of it's magnetic flux from the primary coil(once the primary is loaded).How ever,there seems to be a bit of a mystery here,as the current in the secondary is leading in phase when the load is reduced. This brings the question-->how can it be recieving the magnetic field from the primary before the primary starts to produce current?.

It should also be noted that the secondary(regardless of load) in no way reflects a CEMF to the rotor. So enjoy the video,and post your thoughts.

https://www.youtube.com/watch?v=FFwIF4B7BP4

Tinman here is what is going on:  The windings have a very low coupling factor.  So what the secondary sees is effectively a 10mA p-p current source applied across a roughly 70mH inductor that is in parallel with the potentiometer and 100 Ohm resistor.  Driving at 102Hz:  When the pot is turned down to 2 Ohms the p-p amplitude is 40mV as on your scope, and when the pot is cranked to 1K so that you have 90 Ohms, the p-p amplitude is 800mV as seen on your scope and the phase is advanced ~58 degrees relative to the 2 Ohm case as seen on your scope.

What makes the source look like a current source is a low coupling factor.  (I used a coupling factor of 0.01 in my simulations. ) We know the coupling factor is low from other parts of your demonstrations:  Changing the load on the "secondary" has very little effect on the primary and doesn't affect the current reading on your DMM at all.

So, I think this is a case of mystery solved.

[gyulasun]

Hi Brad,

When you have a few minutes, would you check the inductances of the coils with an L meter, please. I know you included the number of turns for the primary and the secondary coils, still knowing the inductances can further help to understand the operation.
First remove the resistors and check the L values and then attach the 2 Ohm to the secondary and see the how the primary coil may change, this is also an info for the coupling between the two coils.

One more question: did you use some glue to fix the two C cores to each other? If yes, can you tell the gap between the cores, I assume it is a fraction of a millimeter?  I can see the rubber band over the cores lengthwise, so maybe there is no glue layer between the touching surfaces.

Thanks,
Gyula

[TinselKoala]

There is bound to be a little gap in there, or at least not full contact across the core diameter, which is why I drew my diagram the way I did.
It would be interesting to sandwich a tiny ratiometric Hall effect sensor in there somewhere, wouldn't it?

[tinman]

Hi Brad,

When you have a few minutes, would you check the inductances of the coils with an L meter, please. I know you included the number of turns for the primary and the secondary coils, still knowing the inductances can further help to understand the operation.
First remove the resistors and check the L values and then attach the 2 Ohm to the secondary and see the how the primary coil may change, this is also an info for the coupling between the two coils.

One more question: did you use some glue to fix the two C cores to each other? If yes, can you tell the gap between the cores, I assume it is a fraction of a millimeter?  I can see the rubber band over the cores lengthwise, so maybe there is no glue layer between the touching surfaces.

Thanks,
Gyula

Hi Gyula

I would be more than happy to do so,but i dont have an L meter-must get one one day.
The two core's are just being held together with the rubber band-- not glue'd together.