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Author Topic: Daniel McFarland Cook Generator  (Read 190717 times)
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Hi Jeg,

That's very interesting about the brass tube! I've seen some transformer patents that claim increased power from a conductive insert between the coils. I critiqued Matt Watt's Lenz lock transformer design because it had a shunt coil that didn't supply power, but this brass tube would be the same sort of thing. It looks like it would absorb power from the transformer and not add it, so I'm really going to take a look at the info you find on that. I have a hunch I was wrong before.

orthofield
   
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Hi Jeg,

That's very interesting about the brass tube! I've seen some transformer patents that claim increased power from a conductive insert between the coils. I critiqued Matt Watt's Lenz lock transformer design because it had a shunt coil that didn't supply power, but this brass tube would be the same sort of thing. It looks like it would absorb power from the transformer and not add it, so I'm really going to take a look at the info you find on that. I have a hunch I was wrong before.

orthofield

Hi orthofield :)
You might be right my friend. In the same manual at the end of page 176 states that a longitudinally cut of the brass tube will also help to reduce eddy currents. This is a slit across the tube...  What I am trying to locate in the same manual is the why to use a brass tube and not just wind the inner coil straight on the iron core with just a normal insulation like Teflon or PVC. There is some reason for using brass tubes! Leedskalnin also mentions about the use of brass or aluminum..
In the case of using a solid iron bar instead of thin iron wires, Davis states that if the bar be sawed through to its center, this also prevent eddy currents. But again using thin iron wires insulated with varnish is better.
   
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Hi orthofield :)
You might be right my friend. In the same manual at page 176 states that a longitudinally cut of the brass tube will also help to reduce eddy currents. This is a slit across the tube...  What I am trying to locate in the same manual is the why to use a brass tube and not just wind the inner coil straight on the iron core with just a normal insulation like Teflon or PVC. There is some reason for using brass tubes !

IMHO, the brass end caps are are convenient and sturdy mounting surface for the connection terminals and also serve to protect and contain the edges of the windings There is certainly some form of insulating material under the end caps. The slits as said previously prevent the formation of a "shorted turn" by the brass end caps, which would negate most of the inductance of the coil, and would be a huge loss to both forward and flyback energy.


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"Secrecy, secret societies and secret groups have always been repugnant to a free and open society"......John F Kennedy
   
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IMHO, the brass end caps are are convenient and sturdy mounting surface for the connection terminals and also serve to protect and contain the edges of the windings There is certainly some form of insulating material under the end caps. The slits as said previously prevent the formation of a "shorted turn" by the brass end caps, which would negate most of the inductance of the coil, and would be a huge loss to both forward and flyback energy.

That is true ION. Thanks for mentioning this. But why brass tubes between the core and the inner coil? I suspect that there is something more than just a convenient material to give a form for the coils.
   
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Hi All,

I spent most of yesterday afternoon looking for anything in the US or EP patents, or in the old periodical lit, on the interaction of two induction coils of the type we have been talking about (Pre-Tesla for the most part).   

 There were a couple of standard usages of two induction coils in connection or space interaction-- in measuring absolute resistance, in telegraphy, in metal detectors, and in some medical devices. But there were also discussions about how "problems" always arose when two coils were in proximity. Although the issues were never discussed in so many terms, I would bet that there is a lot of near field interaction between two such coils even when they are not connected.
This is especially born out by devices that used two induction coils to detect the presence of underground metal-- the coils were linked in bucking voltage opposition, or differentially, and only show an output when the metal was closer to one than the other. So the interaction of two coils was well known to Cook, as a well read electrician of his day. It was his innovation to connect them so that their voltages added rather than subtracted.

I found two other things of interest. I will deal with the first in this post, and continue with the second in a later post.

Much of the original work on induction was done by Humphrey Davy, and I kept turning up references to his collected works everywhere I looked for interactions between two induction coils.
Davy used solenoids of wire that could be stacked or inserted into each other to study inductive effects. I've attached a small part of this material. Davy seems to be only one of a few people in the literature who have looked at "higher orders" of induction. That is, a primary induces on to a secondary, and then this secondary induces on to a third coil which is not in inductive relation to the primary (I'm not sure about this last). You can see that you can continue to add more orders of induction.
He reports some counterintuitive findings about the 'direction of induction' in different coils, where they are each linked in transformer induction to the next. Attached is a chart he found true in his research. You can see that in the usual primary and secondary the currents are in the same direction, so sec flux opposes that of the primary. He expected to see the same relationship going into higher orders of induction, where a third coil is linked to the second, and a fourth, and so on, but instead he was surprised to find something quite different. The currents of the third order, and currents of the fifth order, are in opposite direction from the primary current, so magnetically support the primary current! (I guess this relates to third and fifth harmonics in some way...)

It seems, in an abstract sort of way, that since the different order coils can have different transform ratios, that you could take a small part of the output from a third or fifth coil, not directly linked to the primary, transform it so the current is very high, and then feed this back to the primary to double the current there.. literally, a loop of transformers! There has to be a flaw :-)

I'll send the whole article if you want-- it is 7 image files.

orthofield

   
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Sorry for posting twice again, there is a glitch in what my screen is telling me.

orthofield
   
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Hi Ion,

I agree completely. On examination of the transformer patent where the conductive material is supposed to improve efficiency it is not oriented to get maximum eddy current as in the brass tube. The brass tube seems to be an easy way to regulate the voltage output of the device, as in the attached excerpt from a long article about "Page's Separable Helices" of the precise form that Cook takes.
   
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whoops, here's the attachment for the use of the brass tube.

orthofield

   
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That is true ION. Thanks for mentioning this. But why brass tubes between the core and the inner coil? I suspect that there is something more than just a convenient material to give a form for the coils.

I would say the inner brass tube may be needed to contain the annealed iron wires. It is clearly explained that the action of the brass tube without a slot will greatly attenuate the output, so I would surmise that this particular brass tube has a slot or or if not, is used also to demonstrate the attenuation effect.

This is a piece of laboratory demonstration equipment and has many modes of demonstration usage, as explained in the pages starting at 174. It use is not limited to just a finished induction coil.


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"Secrecy, secret societies and secret groups have always been repugnant to a free and open society"......John F Kennedy
   
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Hello All

Not to dis-rail the topic, this kinda applies.............

A patent from Brazil, in Portuguese.
Fractional Muon energy generator.
Coil inside a coil run by oscillator at a fraction of the muon vibration frequency???

take care, peace
lost_bro


EDIT:  maybe this post should be moved to 'partnered output coils'
   
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I'll send the whole article if you want-- it is 7 image files.

orthofield

It would be nice if you could! :)
Little hard to visualize how comes that currents of primary and secondary are on same direction. Isn't that depends only of what is the related winding direction of both? Thanks for sharing your thoughts.

 About the interaction between primary and secondary, have you noticed that in partnered coils thread, this was one of the main discussions? And I refer to this:

 EMJunkie:
 @ALL

Floyd Sweet said:

“If the directions of the two signals are such that opposite H-fields cancel and E-fields add, an apparently steady E-Field will be created. The energy density of the fields remain as calculated above, but the value of the E-field will double from E/2 to E"
   
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Hi Jeg,

It would be nice if you could! :)

--Ok, they are attached. I already sent pg. 3



Little hard to visualize how comes that currents of primary and secondary are on same direction. Isn't that depends only of what is the related winding direction of both? Thanks for sharing your thoughts.

--Yes, they are wound in the same direction, and also traveling in the same direction in this case. If you used counter wound coils interacting, then Davy's chart would be a bit different looking, but it would contain the same information.

 About the interaction between primary and secondary, have you noticed that in partnered coils thread, this was one of the main discussions? And I refer to this:

 EMJunkie:
 @ALL

Floyd Sweet said:

“If the directions of the two signals are such that opposite H-fields cancel and E-fields add, an apparently steady E-Field will be created. The energy density of the fields remain as calculated above, but the value of the E-field will double from E/2 to E"

--I don't think that really applies here. That would have to be a different geometry. What we are talking about here is just what successive interlinked orders of coils do. There is no more H-field cancellation than there would be in any transformer.
The main issue I need to resolve by reading deeper, is whether the third and fifth order coils are actually in the field of the other coils, or if they are not inductively linked. There's a big difference!

orthofield
[/quote]
   
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Hi Jeg,

It would be nice if you could! :)

--Ok, they are attached. I already sent pg. 3



Little hard to visualize how comes that currents of primary and secondary are on same direction. Isn't that depends only of what is the related winding direction of both? Thanks for sharing your thoughts.

--Yes, they are wound in the same direction, and also traveling in the same direction in this case. If you used counter wound coils interacting, then Davy's chart would be a bit different looking, but it would contain the same information.

 About the interaction between primary and secondary, have you noticed that in partnered coils thread, this was one of the main discussions? And I refer to this:

 EMJunkie:
 @ALL

Floyd Sweet said:

“If the directions of the two signals are such that opposite H-fields cancel and E-fields add, an apparently steady E-Field will be created. The energy density of the fields remain as calculated above, but the value of the E-field will double from E/2 to E"

--I don't think that really applies here. That would have to be a different geometry. What we are talking about here is just what successive interlinked orders of coils do. There is no more H-field cancellation than there would be in any transformer.
The main issue I need to resolve by reading deeper, is whether the third and fifth order coils are actually in the field of the other coils, or if they are not inductively linked. There's a big difference!

orthofield



Can you post whole article ?
   
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@AC

I tried my three builds and the effect is the same in all three. There is a looping condition that occurs through the two coil pairs, but the effect on even my small cores are not impressive at all in terms of any "magnetic" action to the core ends. One build uses iron wire core and the two others are solid iron core. What they do share is the fine wire primaries are all wound tight side by side and I am convinced this is where the snag occurs in the system. There are so many turns with inter turn cancellation that the actual throughput just drops to a level that could never self sustain itself (if that is the required effect). One of the solid cores is build with a very elaborate insulation using aluminum paint and aluminum foil, but that does not help the tight windings.

I am saying this because in your present build, this may also "wind up" being an issue although your wire is 16awg on the primary that will be interesting to see, but still, I am afraid that the tight winds will produce the same cancellation effect. I am saying this because it may play into the final results that should be well understood from the start.

I don't feel like unwinding one of these builds so I will look to make a new one, with the same core size using 16awg but I need to find a wire with a very thin plastic coating to make sure the turns are better distanced from each other so there is no skin effect between turns. Skin effect for 16 awg starts around 11khz, the looping is actually above my scope capacity of 60 mhz so you see there is only one way to help reduce the turn cancellation and that is to increase turn spacing.

I'll need a few days to find the time and do this and will revert back here to see if there is any major differences.

So, this constant looping with potential gain is a method to increase output if the increased output can be maintained without increasing input, and if there is a way to extract that increase from the system. Cook does not really get into the extraction method.

At the time I took pictures of both solid core builds plus I made one build spec of the non-alu paint device. Two of these are attached just to give you an idea on what not to do.

CBC-1-2.jpg - Build with no aluminum paint
cbc2-coil1-wind-close.jpg  - Photo of primary winding on unit with aluminum paint.

wattsup

PS. Some analogs to this could be the SM TPU, the TK coil (spark initiated - Cook could be using a rasp and many Layden Jars to start her up) or even @otto's ECD rings.


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Wattsup:

I could be wrong but I think your aluminum foil is acting as a shorted turn secondary and will kill the inductance of your coil, unless there is a slot along the length of the aluminum or it's turns are in some way insulated.

The large iron bar will certainly have eddy current losses, which will also sap energy. Best to use fine varnished or otherwise insulated iron wire as a core material to reduce eddy current losses to a minimum.


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"Secrecy, secret societies and secret groups have always been repugnant to a free and open society"......John F Kennedy
   

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Guys,

What ideas do you have for minimizing the parasitic capacitance between the turns of a coil without sacrificing its self-inductance ?

The first thing that comes to mind is using thin low-κ dielectric of high dielectric strength for the wire insulation.  A thick insulation sacrifices the self-inductance of a coil because it takes up space, that could be used for more windings.

What else?
   
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Guys,

What ideas do you have for minimizing the parasitic capacitance between the turns of a coil without sacrificing its self-inductance ?

The first thing that comes to mind is using thin low-κ dielectric of high dielectric strength for the wire insulation.  A thick insulation sacrifices the self-inductance of a coil because it takes up space, that could be used for more windings.

What else?

Back in the days of Cook, I believe cotton or some type of cloth insulated wires were often used as these produced a low inter winding capacitance. These may have had lower dielectric loss due to less inherent capacitance. Rubber insulated wires were also common, but I believe these had higher dielectric loss.

Varnishes,shellacs, and paraffin produced a very thin high capacitance dielectric, with probably a lot more loss.

The less capacitance the lower the loss especially at higher frequencies, one reason Tesla used large air insulated coils with lots of space between turns in his large coils to get a high "Q".

Other winding techniques for close wound coils may minimize the effect of capacitance, such as honeycomb, basket weave, spiderweb coils.

http://www.pa2mrx.nl/UK/PA2MRX-UK.htm?coil%20homebrewing_uk.htm

I'm sure this info can be found in detail in some of the older books


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"Secrecy, secret societies and secret groups have always been repugnant to a free and open society"......John F Kennedy
   
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Seems to me one could wind two strands together, side-by-side--one wire and the other non-metallic fishing line.  Certainly the width of the fishing line would keep the turn-to-turn capacitance way down.  This would be far easier to wind and still maintain accurate/predictable spacing.  It's only when you have the metal wire real close together that they noticeably act like capacitor plates.  With this technique you wouldn't even need insulated wire to start with, solid grounding wire would work just fine.
   

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Cook is very clear on the extraction method. He says put a rheostat in series with one of the coils, then put a load in parallel with the rheostat. The rheostat is there to stop you from having to re-energise the coil. It also prevents overheating in runaway mode.


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VAR is just an angle on a scope. Nothing to see here -  move on.
   
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Seems to me one could wind two strands together, side-by-side--one wire and the other non-metallic fishing line.  Certainly the width of the fishing line would keep the turn-to-turn capacitance way down.  This would be far easier to wind and still maintain accurate/predictable spacing.  It's only when you have the metal wire real close together that they noticeably act like capacitor plates.  With this technique you wouldn't even need insulated wire to start with, solid grounding wire would work just fine.

Good point Matt, I've used a that method but instead of fishing line, I've used nylon or cotton string, especially when winding bare wire single layer coils. If wound on a pre-varished former while still a lttle tacky, the string can be removed after winding and the coil turns remain neatly spaced. Instead of varnish you could also wrap the former with double sided tape prior to winding.


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Hi Forest,

The whole thing would be a lot of little image files, but you can read the complete article here:

https://books.google.com/books?id=4jgWAAAAYAAJ&pg=PR9&dq=%22double+induction+coils%22&hl=en&sa=X&ei=VFfuVMCBAdawogSI2oDACA&ved=0CC0Q6AEwAA#v=snippet&q=on%20production%20properties%20&f=false

go to pg. 127, if the link doesn't take you there.

I mentioned I wasn't sure if the higher order coils were inductively linked to the primary, and you can see that they are not, by the attached pic from the pages above.

orthofield
   
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Hi Forest,

The whole thing would be a lot of little image files, but you can read the complete article here:

https://books.google.com/books?id=4jgWAAAAYAAJ&pg=PR9&dq=%22double+induction+coils%22&hl=en&sa=X&ei=VFfuVMCBAdawogSI2oDACA&ved=0CC0Q6AEwAA#v=snippet&q=on%20production%20properties%20&f=false

go to pg. 127, if the link doesn't take you there.

I mentioned I wasn't sure if the higher order coils were inductively linked to the primary, and you can see that they are not, by the attached pic from the pages above.

orthofield


How did you manage to read it online ? I cannot find any way to do it or to download into pdf file :-(
   
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Hi Forest,

I gave you a bit of the wrong link.
Click on the top block of text, containing the title page, or the 'view all' tab just above the block, and you should go to the full article.
(And the full book! It makes interesting reading since Davy reminds me a lot of us-- continually surprised, delighted to be doing research, and full of things to try :-)
Occasionally google books can be downloaded but most books don't have a download link. I did a bit of research on how to gather data from G books when I started doing heavy searches there, and the best I could come up with is what I use: doing a screen print, and then opening it in paint, cropping it, and then saving it. This is time consuming but works.

orthofield
   
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Hi All,

The attached pdf is useful for calculating or at least seeing the trends in interturn capacitance with different coil pitches, and with different coil formers, which is useful I think. It is based on experiments. He notes that the coil pitch is important-- hence the basket weave coils that ION has mentioned here an in relation to Hendershot. Also, the permittivity of the coil former is included in the formula. But most important is wire length relative to frequency of operation, because this determines whether the coil can be seen as a lumped element, or must be seen as a helical wave:

"We can however use it to deduce the circumstances under which the lumped-component theory breaks down.  The situation is that, at very low frequencies, the superposition of an axial slow wave and a wave following the helix results in a helical phase velocity several times the speed of light.  In this region however, the transmission-line equation asymptotes to the approximation  Tanθ = θ , and the relationship between  R 0   and  v p   is fixed from purely magnetic considerations.  At intermediate frequencies,  v p   decreases smoothly in such a manner as to cause a reasonable match between the transmission-line model and the lumped component model.  As the SRF is approached however, the scattering cross-section of the coil increases dramatically and the helix propagation mode comes to dominate the superposition."

If I understand this correctly, the phase velocity at low frequencies is irrelevant in the Cook case, since it probably naturally self oscillates at high frequency. No matter how much C you get rid of, some will remain, and there will be an LCL self-resonance through the whole device. But near self resonance, the two coils will also be transmission lines with nodes. Given the large bulk inductance and the large interwinding capacitance, the resonance should be in the low Mhz, just as a guess.

Running at high frequencies with less capacitance seems better, from an energy storage standpoint-- the less C, the less energy is stored in C and kept out of induction-- but also in the view that there is an evanescent field around the two induction coils. This is not a transverse wave but a near field induction directly between the core, that at resonance leads to near 100% magnetic energy transfer between them.

This near field or evanescent wave located around two solenoid coils in parallel is now used in Witricity, an ultra efficient wireless power system, that can transfer 40-60% of the power between the source and portable coil, even across a big room. The system works because the magnetic energy transfer is adiabatic-- the near-field magnetic field does not radiate, so no energy is lost from the field, and whatever does not travel to the other core, is returned to the first core in resonance. In order for this to happen, the frequency must be high enough so that the resonators can operate efficiently, while low enough so that the field does not radiate. The natural self oscillation of these large cores would be low enough for this effect to manifest. Wikipedia:

"Resonant inductive coupling: This means the area within about 1 wavelength (λ) of the antenna. In this region the oscillating electric and magnetic fields are separate[6] and power can be transferred via electric fields by capacitive coupling (electrostatic induction) between metal electrodes, or via magnetic fields by inductive coupling (electromagnetic induction) between coils of wire.These fields are not radiative, meaning the energy stays within a short distance of the transmitter".

A case can be made that there is strong direct magnetic energy transfer between the Cook coils, and not only that, that this takes place in a different time frame from the electrical self resonance. The magnetic energy transfer in an evanescent field has been thought by some to take place at more than C, in the case where the coils are closer than 1/4 wavelength... so the ends of the two cores would have almost simultaneous magnetic field strengths and polarities, while the electrical potentials would have to be somewhat different than that.

orthofield








   
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Hi All,

Further reading in the Joseph Henry papers has showed that the phenomena of currents in the third order and fifth order coils can be attributed to the spacing between the coils.
Henry did new experiments where he built an apparatus of two thin air coils on the inside and outside of a glass cylinder (see glasscoil pic). When the outer coil was excited by a Leyden Jar, the inner coil would have a current in the same direction, and induce sparks or move a magnet needle. As one would expect.
Then he built similar coils, and connected them in higher orders as he did previously with the flat solenoids: primary inducing on secondary, secondary inducing (only) on tertiary, etc.
He found different results with these cylindrical glass coils of higher orders than he did with the large air solenoids used before. The higher order currents were all in the same direction as the primary current, unlike the case in the previous experiment with flat solenoids where the third and fifth order currents were opposite.  After struggling for some time to account for the difference, he realized it must be that the large solenoids were more distant from each other than the coils in his second experiment,  just separated by a thin glass wall.
By an elegant experiment he discovered that the distance between two coils determined whether the current in the second coil was in the same direction as the first, or in the opposite. I'll simply attached the passage in question here, since his writing is more elegant than mine.

I'm not sure whether this is relevant to Cook or not-- it's too soon to tell-- but Henry reports that his continued investigations of this phenomena were anomalous, and he didn't include them in the paper because they were too premature.

If you want to read this section for yourself, go to the previous google books url I mentioned, and scroll until you get to pg. 132.

orthofield
   
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