Quest for Fire (or Radiant Spike)

[OrionLightShip]

I've got a couple of ideas and questions but first let's get two things straight. The first is that I don't have much experience with pulse motor/generators. Magnetics is not my thing. The second is that I don't think like most people. I try to keep my thinking out of the box so my ideas are not overly contaminated with "what is known". So most of the time, my ideas are simply way out there and wrong as well. My hope is that at the very least someone will be entertained and at best; my crazy idea will grow into something better in someone else's mind.

In "normal" resonance; we look at a circuit lke a Tesla coil for simplicity of explanation. The current flows into the coil creating a magnetic field which on collapsing becomes the current source to the capacitor (top terminal). The voltage on the capacitor builds to maximum as the magnetic field collapses into the coil. Now the capacitor is the voltage source to the coil. Back and forth they go.

It is said that the distributed capacitance should be minimized because it kills the Q of the circuit. That brings me to the question, how can distributed capacitance affect the Q when the Q is represented as L/R. Where is C in that equation?

Why not maximise the distributed capacitance? Did not Tesla say that it was useful and did he not in his later experiments use the planar bifilar coil he made famous? Did he not talk about the increased capacity of that coil?

[OrionLightShip]

What if you made a coil from very wide copper foil as is shown in this video (start at 4:40). There would be a huge increase in the capacitance which, upon turn off would lend itself to create a very powerful inductive spike.

I don't know what we are supposed to find under the curve of that spike except for current but plenty of people think there is more, so why not make it as large as possible?

Now what if, like in the video I posted, you were to use concentric coils. Let's say you have two concentric coils. The primary is fired (charged) and the secondary coil has a diode so no current flows. Just like a flyback convertor. Now the primary circuit is opened and the field collapses creating current flow in the secondary and also the spike which can be fed into the secondary coii as well.

Perhaps this is just nonsense but it seems to me that you could use the primary in attraction mode and the secondary in repulsion mode. I simply don't have the bench experience to know these things; I have thoughts that create questions that I then try to answer.

[Turion]

A thought

The McCullough generator is (According to Gerard Morin) supposed to be something special and does something that other generators he has tried do not do. Having taken one apart, I can tell you that the generating coils on that particular machine are wound of flat copper braid about 1/2 inch wide or more. Just throwing that out there. Not saying it means a thing.

Dave

[OrionLightShip]

The McCullough generator is (According to Gerard Morin) supposed to be something special and does something that other generators he has tried do not do. Having taken one apart, I can tell you that the generating coils on that particular machine are wound of flat copper braid about 1/2 inch wide or more. Just throwing that out there. Not saying it means a thing.

Dave

That generator is an oddball thing all right.

[Ernst]

I think that distributed capacitance is a source of much confusion. It certainly does not affect the Q as you already mentioned.
Tesla did a lot of research trying to minimize the distributed capacitance but at one point he suddenly stops trying, without stating a reason and without a solution.
I think your thinking is still too much inside the box .
A coil has an inductance, a resistance and a capacitance.
The inductance is the coil's resistance to changes in current through the coil.
The resistance is the coil's resistance to current through the coil (obviously).
The capacitance is the charge needed to create a voltage difference across the coil (exactly like a capacitor, actually).
You can take a coil and let it resonate on its own inductance and capacitance, so without top-load.
I think that the coil's total capacitance is partly made up of this distributed capacitance and partly of the coil's geometry (viewing the coil simply as a conducting cylinder).
It has experimentally been shown that a coil's self-resonance frequency can be calculated solely using the length/diameter ratio and the wire length. That means that the coil's capacitance and inductance (or rather the product of these) are determined by those values alone.
That again, means that by increasing the coil's (distributed) capacitance you decrease its inductance.
I think that the spike you are looking for is the voltage spike created by breaking the current through an inductor. For that you will need a large inductance and capacitance is irrelevant. Just connect it to a 12V battery, wait for some current to flow, and disconnect. You will get your spike. I did this with the HV coil of a distribution transformer (about 4500 H, that is Henries, not mH!) and got some unpleasant shocks.

Does that help? (no, I'm not referring to those shocks )

Ernst.

[OrionLightShip]

It has experimentally been shown that a coil's self-resonance frequency can be calculated solely using the length/diameter ratio and the wire length. That means that the coil's capacitance and inductance are determined by those values alone.

I think this only true when using round wire of known diameter and the pitch (distance between turns). Certainly using flat wire is going to create larger capacitance. How could it not!

That again, means that by increasing the coil's (distributed) capacitance you decrease its inductance.

Increasing the distributed capacitance would not decrease the inductance. It would increase the capacitive reactance and lower the self resonant frequency. Right?

[Ernst]

While you responded, I reread my post and made a few changes because I thought it was not clear enough. You responded to the less clear version...

see this document.
The winding pitch and wire type are not relevant in calculating the resonance frequency.
So by increasing the capacitance, for example by using flat wire, you decrease the inductance, because the product of these two has to remain the same.


Ernst.

[OrionLightShip]

While you responded, I reread my post and made a few changes because I thought it was not clear enough. You responded to the less clear version...

see this document.
The winding pitch and wire type are not relevant in calculating the resonance frequency.
So by increasing the capacitance, for example by using flat wire, you decrease the inductance, because the product of these two has to remain the same.


Ernst.

hmmmm...

I'll have to give this matter the time and thought it deserves.

I always appreciate a logical discussion

[OrionLightShip]

While you responded, I reread my post and made a few changes because I thought it was not clear enough. You responded to the less clear version...

see this document.
The winding pitch and wire type are not relevant in calculating the resonance frequency.
So by increasing the capacitance, for example by using flat wire, you decrease the inductance, because the product of these two has to remain the same.


Ernst.

I'm not sure why you brought that document into this discussion??

There is nothing in that document about distributed capacitance or the lowering of inductance.

In fact, the words induction and distributed are not even in the document. That document is all about propagation velocity.

I completely disagree with this statement.

>>>"The winding pitch and wire type are not relevant in calculating the resonance frequency.
So by increasing the capacitance, for example by using flat wire, you decrease the inductance, because the product of these two has to remain the same."

I don't mind being proven wrong at all... perhaps I glossed over the document and you can show me where I missed the important points.

[Ernst]

Last sentence on page 2:

The function Ph1() can be used to directly estimate the quarter wave Fres from the h/d ratio and the wirelength:=
Fres = (0.39 * ln(h/d) + 1.19) * 75e6 / wire_length (Hertz)

He does also say that the coils used are all "fairly close wound", but my experience shows that this is not a factor of importance.

Also read Tesla's patent on that bifilar coil claim 1:

A coil for electric apparatus the adjacent convolutions of which form parts of the circuit between which there exists a potential difference sufficient to secure in the coil a capacity capable of neutralizing its self-induction, as hereinbefore described.

You can agree or disagree, but maybe you should do a test to verify it?

I have also tested with coils that are not evenly wound, having a tight winding where capacitance is effective and a less tight winding where induction is effective, or the other way around. See attached picture.
This actually does affect the resonance frequency (by 13%).

Well, as I said, the only way to convince anyone is by putting it to the test!
(I have not tested with flat wire, because that is too difficult to wind on a cylindrical coil)


Ernst.

[OrionLightShip]

>>>>"A coil for electric apparatus the adjacent convolutions of which form parts of the circuit between which there exists a potential difference sufficient to secure in the coil a capacity capable of neutralizing its self-induction, as herein before described".

I believe you have misinterpreted this statement. Capacitive Reactance neutralizes Inductive Reactance is how this should be read. Increasing capacitance does NOT change the inductance of a coil.

If you wind a given amount of wire and find the self-resonant frequency and then rewind it Tesla Bifilar style....you will find a lower self-resonant frequency. This is due to the increased capacitance.

Your earlier statement that added capacitance lowers inductance because the product of the two must balance in the equation to equal the resonant frequency is faulty as well. The frequency changes and is not held constant as you suggested.

As always, I could be completely wrong. After all, I have been called a f'ing idiot here at least once.

It really matters not as I don't want to be sidetracked into a discussion about resonance and its relationship to capacitance and inductance.

What I want to talk about is the geometry of flat ribbon concentric coils and effect that increased distributed capacitance might have on the inductive spike and how we might utilize that effect to our benefit.

[Ernst]

After all, I have been called a f'ing idiot here at least once.

Happens to the best of us!
All of us, in fact.

You are right about the bifilar coil. I was talking about cylindrical coils and the wire type and pitch in those. Also I think that your interpretation of Tesla's patent is correct, I just wanted to point out his choice of words. I think there is more to it.
But that is not relevant now.

What I want to talk about is the geometry of flat ribbon concentric coils and effect that increased distributed capacitance might have on the inductive spike and how we might utilize that effect to our benefit.

OK, in that case I think my earlier statement that all you need is inductance, would be my contribution to this thread. If you try to form an mental picture of what happens if you increase the distributed capacitance, then I see charges attracting each other between the coil's windings. I think that would slow them down, but that is based on my imagination only .


Ernst.

[Ernst]

No, just one more idea just popped up:

The spike is the result of the coil's inductance. Do you agree?
Now, if you increase the coil's capacitance, you would need more charge to create a certain voltage.
So.... increasing the coil's capacitance would decrease the effect that you search for.

Sounds logical enough?


Ernst.

[OrionLightShip]

No, just one more idea just popped up:

The spike is the result of the coil's inductance. Do you agree?
Now, if you increase the coil's capacitance, you would need more charge to create a certain voltage.
So.... increasing the coil's capacitance would decrease the effect that you search for.

Sounds logical enough?


Ernst.

You might be right about that. I was hoping that if you raised your charge voltage and current to compensate for the increased capacitance, then upon opening the switch...you still have the inductive collapse but the charge stored in the capacitance will also come over with the spike. You only gain something doing this if you believe in magic under the curve. Frankly, I don't know what is under the curve. Nothing has been proven to me yet.

Really, it would be too expensive to build. I think you would have to 3d print thin nylon rings, glue foil to them and then connect them as is shown in the video from the post #2. Way too much effort but it would make one heck of coil.

Since I left the farm and the shed I built behind and sold my printer, I am satisfied (for now) to simply do thought experiments to keep my mind sharp. I know builders on this forum get frustrated with people that think and don't build.

I just can't help it....for now

However, I do share my ideas openly instead of making people play guessing games!

[Ernst]

I saw that coil of the video and I would be interested in measuring its capacitance and inductance. It is a cylindrical coil that should follow the rule in that document that you were not interested in.
But how to measure this coil's diameter?
How to build it?
I imagine you could make a tool to punch rings from aluminium foil and paper and then stack them up like that man in the video does....
It would take a while, but you'll be rewarded with a magnificent coil!
So if anyone feels like making one....

and a very happy, bright, healthy and prosperous new year!
Ernst.

BTW, there are enough people here that build and do not think.