Confirming the Delayed Lenz Effect

[Magluvin]

So am I to assume that you think two superimposed magnetic fields with matching polarization orientation will not interact ?

No one is saying the coil will be excited by the external field. Why would you imply that ?

Cheers

Well if you have a backing magnet that is of like field to the rotor mag, the field of the backing mag will be in and around the coil when the rotor mag is not. As the rotor mag approaches, it pushes the backing mag field to the opposite side of the coil relative to the approaching rotor mag. It should be a much denser field fluctuations in the coil. And hey, if the backing magnet is set just right, maybe its field is doing all the work in the coil  and the rotor magnet is just manipulating that field within the coil from a distance. So maybe that means less lenz effect on the rotor because its the backing mag that is affecting the coil more than the rotor mag.

Mags

[Farmhand]

Well if you have a backing magnet that is of like field to the rotor mag, the field of the backing mag will be in and around the coil when the rotor mag is not. As the rotor mag approaches, it pushes the backing mag field to the opposite side of the coil relative to the approaching rotor mag. It should be a much denser field fluctuations in the coil. And hey, if the backing magnet is set just right, maybe its field is doing all the work in the coil  and the rotor magnet is just manipulating that field within the coil from a distance. So maybe that means less lenz effect on the rotor because its the backing mag that is affecting the coil more than the rotor mag.

Mags

Yes Mags, My bad that reply was meant for MileHigh. Anyway that could be possible as well. But it would be harnessing the energy of the permanent magnet. If that's cheap to do and works then go for it. But I think core saturation might be a problem with backing magnets, I really don't know because I haven't studied that or experimented with it. Same with polarizing fields, I haven't experimented with it either.

Also even if it may reduce Lenz drag on the rotor, the amount of energy transferred from the rotor to the coils will be in line with Lenz law effects because the energy transferred from the magnet would reduce the amount of energy transferred from the rotor and therefore the associated Lenz drag would be reduced as a result of that..

Cheers

[MileHigh]

Magluvin:

Well if you have a backing magnet that is of like field to the rotor mag, the field of the backing mag will be in and around the coil when the rotor mag is not. As the rotor mag approaches, it pushes the backing mag field to the opposite side of the coil relative to the approaching rotor mag. It should be a much denser field fluctuations in the coil.

But that doesn't happen if you are implying "denser field fluctuations" will mean a higher voltage/current output from the coil.  That's the point I am making.  The coil only sees and reacts to the approaching rotor magnet. The backing magnet may as well not be there.  Feel free to do some tests.

I haven't checked your link yet but I suspect it may have to do with an external magnet affecting the ferrite core of an inductor.  You can imagine that it reduces the ability of the core to store magnetic flux in a volume.  That will affect the coil because the core affects the coil.  So in this case the presence of a magnet has an indirect once-removed effect on the coil.

MileHigh

[conradelektro]

Hi Conrad,

Some comments on sensor coil and reed switch:  yes, sensor coil can be small and handy and easy to explore its best position. Question is what you drive with it? say you drive the base-emitter of a bipolar transistor then I think a reed switch can also do that job in the same way when you use a few kOhm resistor in series with it which also serves as a base current injection to the transistor anyway so the current can be small via the reed. And you can find the same good position for the reed but I agree that many times a reed may need a separate control disk with small magnets on it to work reliable. On control disk I have referred to you already at a Bedini motor (zero force motor 2nd version, see second video link below) and he used reed switch, at rotor speed I estimate at least to be several thousand rpm. Of course a separate control disk needs some more job and material to build and anything you use is fine with me,


Would like to show you a video on Bedini's so called 'zero force motor'. It seems very simple, at least this first version he showed a few years ego at energetic forum (but later he deleted it). See this link http://www.youtube.com/watch?v=3kpDMMcNQxc someone uploaded it again.
You can see a rotor with some cylinder Neo magnets, all like poles out and the coil is positioned tangentionally to the rotor. He says it is a no Lenz, no backemf motor, a more advanced version of this can also be seen on youtube but it has a ring shape stator with coils on the ring, its link is here: http://www.youtube.com/watch?v=4TICXxP1jI4  Unfortunately, the very little info is what could be guessed from these videos, no further details have been given.

The coil position as shown in the first video above i.e. turning it sideways instead of the 'usual facing magnet' position was tested also by Naudin, you may have seen it in the right hand side scope shot here: http://jnaudin.free.fr/images/magconfig.gif  (and you can read about his findings in this link: http://jnaudin.free.fr/html/mromexp.htm )

So what I would suggest is first to explore what waveform your present ring magnet would induce with its changing poles in such sideway positioned coil (because the interesting waveform shown on the right hand side is always made by a single pole, (only the voltage polarity flips) either a N or S but not by suddenly changing poles your ring magnet presently has.
Probably the induced waveform you may see will be different from that.  I editied your earlier magnet-coil position drawing to show 2 coils tangentially fixed wrt the rotor magnet above and below it (on the left and the right hand side of the ring magnet) or I considered the two coils either at one side or both sides of the ring (in this latter case coil length may be an issue). I show you all this because both pole ends of the drive coils are utilized. The ON time should be figured out of course (probably 25% is good).

These are only suggestions, of course I do not mean in any way to 'influence' your own way what kind of setups or circuits you build.

rgds, Gyula

PS If there is a television and video repair service near to your location, you could inquire about faulty VCR heads  (I mean even rotors with some aging problem in their bearings) because they are replaced to new ones and the old one is not renewed) such rotors can still be very useful for tinkering.

@Gyula:

Again, great suggestions. I think I can do some tests with this "lengthwise coil arrangement".  I just have to bend a suitable "coil holder" from aluminium and mount it near my ring magnet spinner.

I see the advantage of a control disk with small strategically placed magnets. May be my building skills advance, then I will dare to go into more complicated designs.

But as always, there are more ideas than time and capability to build them. I collect your suggestions and will go back to them when testing, advancing and redesigning my set up.

I do not mind corrections, new ideas and suggestions.

I have this Commutation Encoder Module with Codewheel AEDB-9340-2000 (180 positions) http://www.avagotech.com/docs/AV02-0075EN. One day I want to build a pulse motor controlled by a microprocessor (Arduino) and this Encoder together with a transistor H-Bridege. That would give endless control possibilities (pulse width, timing, commutation, shorting).

I found a VCR on ebay, if I am lucky I get it for a few Euros. (And of course I dumped two VCRs a few years ago, but my house would be full if I hoarded everything.)

Greetings, Conrad

[profitis]

thanx farmhand.the reason why i ask is because the physicist called steven.j.smith(google steven j.smith magnetothermodynamics) has analysed the thermodynamic cycle of a simple paramagnetic(temporarily magnetised only while current runs)  inductor core with coil and has found that when you suddenly break the current the temperature of the paramagnetic material core drops momentarily below its curie point thus at that instant it changes from a paramagnet into a ferromagnet thus re-enforcing the collapsing magnetic field and giving an extra boost to the kickback current pulse.