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Author Topic: Daniel McFarland Cook Generator  (Read 167796 times)

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Are we missing something ?

I have copied an excerpt from a newspaper article printed in 1886 by the Cincinnati Commercial Gazette.


 " Some months later the Cincinnati reporter was invited to Cook’s shop where he had to sign an agreement not to reveal the secrets he was to witness.


The writer noted that Cook worked in a stable with a horse in the next room, and continued, “The machine was rudely constructed for Mr. Cook made it all himself with a few old tools that had done too much service already. Parts of it were made of wood and the whole was put together in a not very artistic manner.”


“I tested the current in several ways and found it very powerful. Having made electricity somewhat of a study, I was surprised at the simplicity of many of the principles. The manner in which he expects to get the results is theoretically correct and there is no mechanical difficulty which he has not already overcome.”


“After examining this machine carefully in all its parts I was conducted to an adjoining room where, on a table, sat a smaller model of more accurate make. It contained a much better arrangement of the parts, and from what he showed me I am compelled to believe all that Mr. Cook had told me.” "

By now I think most who have studied this patent, the pairs of coils were probably bought from Davis's.

The reporter mentions machine, obviously there's more to the device than the patent drawing shows.

So, what if we were to put an interrupter in the circuit ? A simple attracted armature that oscillates between the two coils.  Rather like the old telephone bell ringer but substitute the bells for contacts ?   

Just a thought that occurred to me the other day after reading another article on D McF Cook's flying machine.

Cheers Grum.


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I think you are correct. It was understood that induction coils came with an interrupter, otherwise they would not work. There was no AC in those days. (1880s). There would be no point in even mentioning the interrupter in the patent.

http://www.sparkmuseum.com/INDUCT.HTM


Going forward to 1915, Benitez DID put an interrupter into his patent because by that time AC was common place.

I've just remembered that when I had my freak result with a MOT the solder joint was dry and it obviously created an interrupter of sorts.

My 2 pennies worth.


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I'm glad you found that article and the same conclusions as I found. Unfortunately McFarland patent was tampered not only by removing the missing circuit but also by not mentioning the correct "modus operandi" and so on... Keep digging
   

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I'm glad you found that article and the same conclusions as I found. Unfortunately McFarland patent was tampered not only by removing the missing circuit but also by not mentioning the correct "modus operandi" and so on... Keep digging

Dear Forest.

I could do with some kindly soul donating one of these !! " Bell Set No 50 C "

I scrapped hundreds of these along with telephones during my time on the " Comms " section, now amazingly collectible !!

Cheers Grum.


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A study of the efficacy of certain types of long coils over short squat coils would be worthwhile in the Cook endeavor. There might be a magnetic cascade effect with small input currents in the long coils.

Long coils were used in early dynamo electric machinery at the turn of the century due to their high efficiency.

The textbook formulas for iron core coils (especially very long ones) does not address the possibility of a domain cascade or avalanche effect, as far as I know.


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A study of the efficacy of certain types of long coils over short squat coils would be worthwhile in the Cook endeavor. There might be a magnetic cascade effect with small input currents in the long coils.

Long coils were used in early dynamo electric machinery at the turn of the century due to their high efficiency.

The textbook formulas for iron core coils (especially very long ones) does not address the possibility of a domain cascade or avalanche effect, as far as I know.

Dear ION.

Is this the scenario to which you are referring ?

http://jnaudin.free.fr/dlenz/DLE22en.htm

Depending on the operating frequency a number of nodes will appear along the core.

Cheers Grum.


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Dear ION.

Is this the scenario to which you are referring ?

http://jnaudin.free.fr/dlenz/DLE22en.htm

Depending on the operating frequency a number of nodes will appear along the core.

Cheers Grum.


Coils made from insulated iron wires :-)
   
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A study of the efficacy of certain types of long coils over short squat coils would be worthwhile in the Cook endeavor. There might be a magnetic cascade effect with small input currents in the long coils.

Long coils were used in early dynamo electric machinery at the turn of the century due to their high efficiency.

The textbook formulas for iron core coils (especially very long ones) does not address the possibility of a domain cascade or avalanche effect, as far as I know.

I was referring to ordinary iron core coils wound with copper wire and the iron core having a large length to diameter ratio, as in early telephone relays or dynamo-electric machinery as in the attached.


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With short coils you cannot make use of the high permeability to get high flux at low current.  But with long coils you can.  So if you want maximum flux at the pole face for minimum current, hence minimum resistive loss, you use a long coil.  It all comes down to the demagnetization factor.  My paper "Energy around coils and magnets" tells you how to use Nagaoka's factor as the demagnetization factor for permeable rods.  Don't have it to hand at the moment as I am away in our motorhome (RV if you are American).

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With short coils you cannot make use of the high permeability to get high flux at low current.  But with long coils you can.  So if you want maximum flux at the pole face for minimum current, hence minimum resistive loss, you use a long coil.  It all comes down to the demagnetization factor.  My paper "Energy around coils and magnets" tells you how to use Nagaoka's factor as the demagnetization factor for permeable rods.  Don't have it to hand at the moment as I am away in our motorhome (RV if you are American).

Smudge

I was merely musing on the idea that a very long iron core wound over with copper wire in the most efficient way could be very good generator of flux, and as such there could be a domain avalanche effect at some critical size, even with a small current input. Cook's coils were supposedly over three feet long and worked best with a core of small diameter iron rods. In other words, is it possible with such a long magnetic structure that flux would suddenly non-linearly increase  to saturation at some relatively small value of input current?


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I was merely musing on the idea that a very long iron core wound over with copper wire in the most efficient way could be very good generator of flux, and as such there could be a domain avalanche effect at some critical size, even with a small current input. Cook's coils were supposedly over three feet long and worked best with a core of small diameter iron rods. In other words, is it possible with such a long magnetic structure that flux would suddenly non-linearly increase  to saturation at some relatively small value of input current?
I am sure there is such an effect.  There will be a propagation delay along the core and with a fast enough rise time of the input pulse that delay will be seen in the manner in which the flux rises.  The long core can be considered as a form of transmission line.  But it is a transmission line working in the magnetic domain.  From the classical point of view it is a transmission line having a reactive characteristic impedance.  I have used classical theory to show that such a line, when terminated in a reactance, exhibits negative input resistance that can lead to self oscillation.  So IMO there is something of substance in your musing.

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I have decided to bump this topic to bring it to the forefront.  It got mentioned in Chet's Private place holding spot and that triggered my interest again.  Having given more thought to the subject I am sure that Cook's long solenoids of many turns of fine wire wound onto very long Fe rods would act like a transmission line or delay line.  And those ferrules at each end of the secondary would act like shorted turns.  A good shorted turn will act to block the passage of flux so now we have a transmission line with blocks at each end, I see there a resonant condition something like a half wavelength transmission line shorted at each end.

Turning my attention to where any excess energy could come from I assumed some AC flux in a core and looked for where there could be some additional flux at a 90 degree phase, and it struck me in a light bulb eureka moment that those pesky ferrules at each end of the secondary could have something to do with it.  I see the two main fluxes in the two cores phased together because of their close proximity, then the currents in those shorted turn ferrules will be at 90 degrees to the flux.  Those currents will create a magnetic field extending out from each ferrule and intersecting part of the opposite core.  Now we have just part of each core having a combination of the main flux flowing along the length of the core plus another flux that is at a 90 degree electrical phase.  And that additional flux flows sideways into the core, along a small section and then sideways out again, it does not add to the main flux along the core.  But it does affect the mmf drop along the core.

Modelling an inductor in the magnetic domain you have an mmf of Ni ampere-turns driving flux through a reluctance R, where for long solenoids R is the reluctance of the Fe core.  Normally mmf and flux are in phase, but if there is some external influence adding some quadrature-phase mmf to just part of that long reluctance we will get a small phase shift between mmf and flux.  Now the phase between current and induced voltage will no longer be 90 degrees, it will be slightly shifted.  Our otherwise perfect inductor will no longer appear as a perfect reactance, it will have a resistive component and that resistance can be either positive or negative depending on which way the phase has shifted.  If a negative resistive component exceeds the actual resistance of the coil we have self oscillation.

I intend to explore this possibility further and if it looks good I'll post it here.  Furthermore I will explain how the anomalous energy actually comes from the atomic dipoles responsible for the ferromagnetic property of the Fe.
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Smudge

Thanks for taking another look at the Cook device. I had not considered the shorted turn effect of the "ferrules". I assume you are referring to the bands at each end that have the connection posts. This may be the ingredient that was missing from other failed replications.

It seems that this method of drawing some types of coils was common for patents back in the 1800's. Back then DC was commonly used to energize such coils so the shorting effect of the ferrules may have gone unnoticed unless used in an AC system of reasonable frequency such as self interrupted spark coils.

A good starting point for research would be a few empirical experiments where we keep the ampere turns and gauge wire the same but vary the length of an electromagnet, again keeping the overall mass of the core the same in each case and see how this affects the B-H curve and the inductance.

Does it begin to depart from the standard formula at a certain length of core?

Regards


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Smudge

Thanks for taking another look at the Cook device. I had not considered the shorted turn effect of the "ferrules". I assume you are referring to the bands at each end that have the connection posts. This may be the ingredient that was missing from other failed replications.
Yes, I think those bands and connection posts were a common feature of large wire-wound resistors at that time.  Transformers were virtually unknown.

Quote
A good starting point for research would be a few empirical experiments where we keep the ampere turns and gauge wire the same but vary the length of an electromagnet, again keeping the overall mass of the core the same in each case and see how this affects the B-H curve and the inductance.

Does it begin to depart from the standard formula at a certain length of core?
Not sure what you consider a standard formula for long cores.  The Nagaoka formula for single layer air coils is well known and I extended that to cored coils in my paper attached.  It strikes me that the connections between the coils was as shown in the image attached and any currents induced at start-up would be as shown.  Note there is no transformer action, the primary and secondary currents are in phase and simply give a sum mmf.  The flux in the parallel cores would flow in opposite directions, see the FEMM image showing the flux lines connected through the air.  As such this just acts like a single inductor and without any other connections the induced currents at start up would simply decay exponentially.  I think those added shorted turns really are the things that do the trick so that must be the path for investigation.

Just to whet people's appetites also here is a paper I wrote a long time ago showing that there is considerably more magnetic energy stored in the space between atoms than we supply when we charge a ferromagnetic cored coil with current.

Smudge
   

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A very good read, thank you for that O0

Regards

Mike 8)


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This is to show that current induced into a shorted coil will then create flux in an adjacent magnetic circuit.  The first image show the FEMM set-up where I model two C cores each with a single layer winding over the entire core.  I put a shorted turn of copper strip around one coil, then put current through that strip.  FEMM gives the flux linkage into the two coils.  The second image is the FEMM result.  You can see that the flux linkage to the adjacent coil is almost one tenth of that into the main coil, so it is significant.  If the main coil is energised with AC this will induce current into that shorted turn and that will then induce flux into the adjacent circuit.  I maintain that the current in that shorted turn will be 90 degree shifted from the driving flux there, hence the flux induced into that adjacent coil will also have that 90 degree shift.  With two identical coils each having a shorted turn we have the means for inducing 90 degree flux into each, and we can do this such that the system will self oscillate.
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Here is a suggested experiment where we connect two systems together and resonate with a capacitor.  It is tickled into resonance with say a single turn driven from a signal generator.  With the two coils widely separated we measure the Q or bandwidth.  Then bring them closer together to see whether the Q changes.  We could also invert one of the coils and see what effect that has, we should see a change of Q there.  If the Q goes up with the correct orientation as expected then you have a measure that the effect is real.  If you achieve self oscillation then you are a winner, but beware you don't blow up your sig gen.  Maybe a fuse in the connecting wire would be a good thing.
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Hi Smudge

Here is an interesting item. By changing R an AC current seems to be induced into the secondary.

This works, was done by me back in the 90's, but I expect the core of the transformer is picking up ambient waves, but are they magnetic or electromagnetic? hum :-\

Regards

Mike 8)


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"All truth passes through three stages. First, it is ridiculed, second it is violently opposed, and third, it is accepted as self-evident."
Arthur Schopenhauer, Philosopher, 1788-1860

As a general rule, the most successful person in life is the person that has the best information.
   
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Hi Smudge

Here is an interesting item. By changing R an AC current seems to be induced into the secondary.

This works, was done by me back in the 90's, but I expect the core of the transformer is picking up ambient waves, but are they magnetic or electromagnetic? hum :-\

Regards

Mike 8)
Not sure what you mean here, all I see is a shorting switch across one half of the winding.  What is the changing R?
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Lets say the primary coil has 1 ohm resistance at the point where the capacitor is connected. The tap is in the middle, so each half of the coil has 1/2 ohm, so when the switch is open R=1, when closed R=1/2. The inductance will change as well, but not 50% more closer to 25%, eg. full coil 94mH and half 23mH (as tested on a transformer I have here).

The test was done with a reed switch and a magnet oscillating past the reed switch on the end of a piece of plastic.

1.  There could be induction from another source eg house mains, but the output was not 50Hz orientated, nor the oscillation source which was shielded.
2.  Any other electromagnetic wave in the surrounding area of the transformer, but there was no other wave visible at the time.

So what is creating the secondary sine wave output?

Regards

Mike 8)


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"All truth passes through three stages. First, it is ridiculed, second it is violently opposed, and third, it is accepted as self-evident."
Arthur Schopenhauer, Philosopher, 1788-1860

As a general rule, the most successful person in life is the person that has the best information.
   
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Was the oscillation in phase with the reed switch opening and closing?  Or did having a closure conjure up some other oscillation while the switch was closed?
   
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OK I have done some more with FEMM by applying current to the shorted turns so as to buck the flux in the cores, see image attached.  The two main coils are in series driven with current and with the flux bucked under the shorted turns the inductance is 1.23x10-4 H.  I used 1 amp there so the flux linkage from the main coils is 1.23x10-4 Webers.  The current in the shorts needed to do that bucking was 70 amps, then using the data previously obtained for the cross coupling from those shorted turns of 2.741x10-7 Webers for 1 amp, this becomes 1.918x10-5 Webers.  So the expected quadrature flux is about one tenth of the in-phase flux.  That would produce phase shift between input current and induced voltage of about 99 degrees instead of the usual 90 degrees.  Quite significant and enough for self oscillation.
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OK I have done some more with FEMM by applying current to the shorted turns so as to buck the flux in the cores, see image attached.  The two main coils are in series driven with current and with the flux bucked under the shorted turns the inductance is 1.23x10-4 H.  I used 1 amp there so the flux linkage from the main coils is 1.23x10-4 Webers.  The current in the shorts needed to do that bucking was 70 amps, then using the data previously obtained for the cross coupling from those shorted turns of 2.741x10-7 Webers for 1 amp, this becomes 1.918x10-5 Webers.  So the expected quadrature flux is about one tenth of the in-phase flux.  That would produce phase shift between input current and induced voltage of about 99 degrees instead of the usual 90 degrees.  Quite significant and enough for self oscillation.
Smudge

Smudge,

Since the mmf for the rings is 70 ampere turns, could we replace the single turn with 70 turns and drive the "shorts" with the 1 amp main coil current?

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Dear Smudge;

Can you describe why using gapped "C" cores would be better than the 3' to 4' straight cores used by Cook and also why the shorted turns will be better placed at the center of the cores rather than the ends, as you believe Cook did.

I'm enjoying your progression of ideas on this topic, and wonder what a FEMM model of the actual Cook coils would produce.

Also, what gain would be required to allow oscillation with 90 or so degrees of phase shift. My gut feel is that with approx one order of magnitude reduction in gain you could at best get a damped oscillation but not a steadily increasing oscillation as the coils mirror current to each other. How did you reason this out?

Kind regards


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Was the oscillation in phase with the reed switch opening and closing?  Or did having a closure conjure up some other oscillation while the switch was closed?

To be honest I can't remember, it was 20yrs ago, I would have to do the experiment again and I don't have time atm. J.L.Naudin did the same test at the time and got the same results, he said it was parametric but could not point to where the current came from, but possibly the magnet.

I don't want to sidetrack the thread, it was just a thought after reading your paper.

Regards

Mike 8)


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"All truth passes through three stages. First, it is ridiculed, second it is violently opposed, and third, it is accepted as self-evident."
Arthur Schopenhauer, Philosopher, 1788-1860

As a general rule, the most successful person in life is the person that has the best information.
   
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