The bifilar pancake coil at its resonant frequency

[MileHigh]

So my answer to the question about if current changes direction or no: There is not any conduction current when switch opens! Just the reaction of the opposing in nature coil, which is pure voltage.
The argument is based on a wrong base.       

Jeg, this important topic is all fully documented in the thread that Carroll linked to, and I suggest that you read it.

You are quoting one of the biggest misconceptions about coils that goes all the way back to the late John Bedini. It's the false idea that when the switch opens the coil produces "pure voltage" and no current.

If there was one amp of current flowing through the coil before the switch opens, then just after the instant the switch opens there is still one amp of current flowing through the coil.  However, because the switch is open, the current flow through the coil decreases rapidly to zero.

Here is the symmetry:

When you short-circuit a capacitor, the capacitor outputs voltage that decreases rapidly to zero and there is a strong pulse of current that also decreases rapidly to zero.

When you open-circuit an inductor, the inductor outputs current that decreases rapidly to zero and there is a strong pulse of voltage that also decreases rapidly to zero.

More symmetry:

A coil is absolutely NOT something that produces "pure voltage and no current."  What it really produces is is "pure current and the voltage is dependent on the load."

A capacitor is absolutely NOT something that produces "pure current and no voltage."  What it really produces is is "pure voltage and the current is dependent on the load."

It is very important that you understand this so that when you work on your bench you have a better understanding of what is taking place.

Even the tiniest coil when connected through a switch will ionize the air and create a conductive plasma when the switch opens.  This is because a coil acts like a current source.  If you do not know what a current source is then please research this important topic.

MileHigh

[citfta]

Acca

I totally disagree with your post.  The only reason someone can't learn on this forum is because they refuse to learn.  I have posted several links in this thread for those that are willing to learn.  Here is only one of them.

https://www.quora.com/Why-does-the-current-direction-change-when-an-inductor-discharges

After I posted it apparently no one took the time to even look at it.  It was obvious they didn't because of their inane comments.  I also posted this link to a discussion thread that had lots of info about the myth of reversing current when a coil discharges.

http://overunity.com/16203/inductive-kickback/

After posting that I was told there was no reason to read it.  We can't help people learn if they refuse to even look at what we are trying to show them.  It appears you would rather let them continue in their confusion rather than have those of us that know better actually try to help them.  You are putting down the very people that are doing exactly what you claim they are not doing.

Carroll

[nelsonrochaa]

Good Nelson, you are all butt hurt for being told that your ad hominem attacks and straw man arguments are unacceptable.  It doesn't feel good to be labeled the "bad guy," does it?  It upset you to the point that you had to do the "big thread shakedown."

Just check your behavior and simply act like a normal person.

I'm hurt ? ohh really  ? You upset me ? not so sure .. but i don't have your time to answer you, ever time you post , myself don't live without work   .

Bad guy me ?
I did not know about that my facet , and i really wonder how bad i could be in your mouth and in your words you are hilarious .

You should really check you behavior , because you act like a a kid that someone steal their toy and go call the papa .
Don't be ridiculous , you simple don't accept that someone disagree from you but i will tell you again :

I'm owner of myself Thoughts , and is not you or anyone that influence me just to please, or be part of the "elite" of Illuminated group .
I have the right of disagree, when I do not agree with some affirmation ,  and myself are free to  learn too , with other ideas or new concepts that you could not agree or even know or understand  .So simple like that .

I just say, like someone could read in the posts i write , that pancake coil have special properties and that to me is irrefutable, under what i see in practical work and others already saw , something that you don't know but  only theorize .

But even that why you struggling to convince me ? No one impose nothing to you , in fact i repeat lot of times that even disagree i respect your opinion , and i did not concentrate so much energy to convince you from the opposite Well no sir ?

To you even Nikola Tesla seems that not have the "mathematical background"  to model their own systems . That is you worst shot  , that i could hear and only could be like a bad joke , or simple nonsense .  is my sincerely opinion .

Do not bother to continue to convince me with your copy past, and with your ideas. If I were looking for what you have make copy past, i am able to do it in the most diverse sites where you are going to get the information, and in many others.
Simple like that.

Nothing more to add .

Have a nice day , and enjoy

Nelson Rocha

 
   

[nelsonrochaa]

Another quote form Tesla's patent 512340 (bifilar coils):

I have found that in every coil there exists a certain relation between its self-induction and capacity that permits a current of given frequency and potential to pass through it with no other opposition than that of ohmic resistance,

or, in other words, as though it possessed no self-induction.

This is due to the mutual relations existing between the special character of the current and the self-induction and capacity of the coil, the latter quantity being just capable of neutralizing the self-induction for that frequency. It is well-known that the higher the frequency or potential difference of the current the smaller the capacity required to counteract the self-induction

Yes Evostars , the father of pancake coils  say exactly that "it possessed no self-induction"  only need find the right frequency to that happens , and seems is that that some really don't agree  , and that is the reason to the compass not show any deflection even when  drive a load , not by the high frequency like someone say .

Cheers


Nelson Rocha

[TinselKoala]

What is this, low-hanging-fruit day?

http://www.youtube.com/watch?v=wd5w8KhYrQk

OF COURSE it is frequency dependent.

What do you think "IN EVERY COIL" means in that quote? He is NOT ONLY referring to his bifilar winding.
As Tesla says in the patent, the Tesla Bifilar winding has increased interturn capacitance which reduces
the EXTERNAL CAPACITANCE needed to produce this effect on self-inductance at a given frequency and voltage.
In his day, high-voltage capacitors were bulky, expensive and unreliable, so there was a good reason to
try to reduce the external capacitance required and to increase the self-capacitance of certain coils which
he used in his "tesla coils" of various designs. Note the title of the patent: Coil for ELECTROMAGNETS.
But the effect itself can be obtained WITH ANY COIL and suitable external capacitance.

So how do you get a magnetic field in your electromagnet without self-inductance? How do you transfer
power to a secondary coil without an alternating magnetic field? By magic? Funny, then, how well
mathematical models work for coil behaviour when they don't have to include magic in the calculations.

http://www.nde-ed.org/EducationResources/CommunityCollege/EddyCurrents/Physics/selfinductance.htm

Many people who should know better choose to misinterpret Tesla's patent, and not only this one.
And many people seem to confuse inductive reactance with self-inductance. 

(And Tesla isn't the "father of pancake coils". At best he's a cousin or nephew.)