The bifilar pancake coil at its resonant frequency

[MileHigh]

What do you know the patent is all about?

[Magluvin]

Well I spent literally all day yesterday here on this and made the coil and did the preliminary measurements.

Today I reread the patent, of which, googles rewrite needs some work, so stick with the original.

Ok, here is my vision on this..

'Every' coil, inductor, has its own capacitance. If it is a 1000 turn normal coil and we apply 100v, the voltage differential between turns is .1v. The actual capacity between turns, using the same number of turns, the same wire size, the same winding design, is the same for a bifi coil and the standard. That value does not change between the 2 coils as the proximity and surface area of each turn and its adjacent turns are all physically the same. But the same coil described above in a bifi setup has 50v potential difference between turns. He describe the difference between the 2 capacities of these 2 differently wound coils is 250,000 times!

There is the familiar 3d example out there that describes the bifi as 100 turns and 100v applied, where the normal coil has only 1v potential difference, yet the bifi example still shows 50v between turns just like Teslas 1000 turn example. So the more turns that you use on a normal coil, the lower the potential difference between each turn is and thus lowering the working value of the capacitance by lowering the potential charges the capacitance has to work with. If it were a 10,000 turn regular coil with 100v, the potential difference between each turn is now only .01v charge, yet a 10,000 turn bifi would still have 50v between turns.  So what is the difference for the 10,000 turn example, 2.5mil times??

So the more turns of a regular coil, the capacitance becomes less and less significant compared to the increased inductance for said coil because the potential difference between turns becomes less and less.  Or even if the more turns there ends up more turns with capacity between them, as that capacity increases the potential for each adjacent pair decreases, so for arguments sake, lets say the capacity as a whole figuring in the potential diff,  may remain the same for whatever amount of turns for a normal coil, but inductance increases. With the bifi, that potential difference remains the same no matter how many turns, and the more turns the more physical capacity. So for a bifi the more turns, the total capacity increases. So just those facts show that these 2 different coils definitely have some major differences as the number of turns increases for each. 

A 'perfect' example would be a 2 turn coil. it is essentially a bifi winding! 50v between each adjacent turn. As soon as we make it 3 turns, we have only increased the capacity by 2 and we have decreased the potential to 33.3v between turns. 4 turns increases capacity by 3 and brings sown the potential to 23v. So with that I suppose we can determine the effective capacitance as to whether it is increased, decreased, or remains the same as we increase the number of turns for a standard coil.

So mow the bifi.
2 turns, 100v 50v cap potential
3 turns, 100v 50v cap potential  and double the physical capacitance
4 turns, 100v 50v cap potential  and triple the physical capacitance

100 turns, 100v 50v cap potential and 99 times higher capacity!!   So something is very very different between the bifi and the normal coil self capacitance as the turns for each increases.




I believe the showing of a flat coil in the pat is mostly for easier understanding for the reader of the difference in how the 2 coils are setup and the relationship between turns throughout the winding, as he does say that this can be applied to any way of winding coils, inductors, etc.

Going back to the pat, here are things he says about freq and 'potential'

"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."

Now if we look at a 10mh coil of normal winding, if what he says is so, then there must be an initial current in the coil that is allowed to fill the capacity avoiding the inductive delay. But it just so happens that the capacitance of the normal coil has so little value due to the potential between each turn pair is a result of the input divided by the number of turns. So that is something we should look at, if we can. Is there an initial current that enters the normal coil to fill its cap at the instant of applied input, that is just so small we do not see it, unless we look for it? And if we can see it, then we need to compare the bifi in the same manner.


"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; hence, in any coil, however small the capacity, it may be sufficient for the purpose stated if the proper conditions in other respects be secured in the ordinary coils the difference of potential between adjacent turns or spirals is very small, so that while they are in a sense condensers, they possess but very small capacity and the relations between the two quantities. self-induction and capacity, are not such as under any ordinary conditions satisfy the requirements herein contemplated, because the capacity relatively to the self-induction is very small."

In the past I have said this all before. Being that the capacitance of the normal coil IS seemingly very insignificant, it is still there. And the freq he is speaking of is possibly very high, so that initial input I spoke of just may be at a very high freq and small due to the capacity being very small. If for the 10mh example the capacity is in the pf and the potential is very low, then to see it we may have to have very good equipment to do so. Dunno yet. I have a 1g scope. I know there is much better. How Tesla came up with this stuff is mesmerizing.


So with that, this is the area I wish to look into. Like I said to MH, the resonance part is not what I am look for right now.

Gota git. Be back later

Mags

[MileHigh]

"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."

Once you have found the self-resonant frequency of your coil by looking for maximum voltage amplitude on your scope, the above suggests a second test to confirm your findings:

[signal generator] -> [coil] -> [non-inductive resistor] -> [ground]

Suppose your coil is two ohms and self-resonates at 200 kHz and you use a 10-ohm non-inductive resistor.

If your signal generator is set to output 12 volts peak-to-peak at 200 kHz then you should observe a 10-volt peak-to-peak signal across the resistor that is in phase with the signal generator if the coil is acting like a series LC circuit.  Then, as you increase the frequency you should see the voltage across the resistor start to drop as the impedance of the inductor starts to predominate.  Likewise, as you decrease the frequency you should see the voltage across the resistor start to drop as the capacitance starts to predominate.  However, will that really happen considering that we are dealing with a distributed capacitance and not a true series capacitance?

There may be a surprise, and at the self-resonant frequency of 200 kHz, there is no voltage across the resistor.  That would be explained by the coil acting as a parallel LC circuit at the self-resonant frequency.

An astute experimenter would measure the self-resonant frequency of his coil by looking for the maximum voltage swing, and then move on to this second test and do a full frequency sweep looking at the voltage and phase across the non-inductive resistor.  There may be some "surprises" to be found where there may be one or more "poles" and "zeroes" in the observed voltage and phase across the non-inductive resistor.

[TinselKoala]

@Tinman,

My vendetta with TK goes back to one of his earliest coil comparison videos nearly eight years ago. I had a large coffee can size solenoid bifilar professionally wound at an electric motor shop in Eureka California around the same time, and packed the core with welding rods for my first Bedini SSG. I already knew how to charge and pulse the coil from Dave Dinan, but I really didn't know exactly what to expect. I shocked twice; Once to shock charge and ring  it, then a second time. The spark from the second swipe was around ten times as large as the ring pulse. Well, everyone's already heard about the rack of carving knives that careened about twenty five feet towards the coil. The coil was unaffected by the attraction.

So you admit that you have been waging a "vendetta" against me for "nearly eight years". 

Do you also admit that you have been posting the insults and fake claims about me, in a deliberate effort to damage me personally, affect my reputation negatively, and affect my income and livelihood? Your emotive insults are also clearly designed to affect my health as well, by raising emotional responses in me which increase heart rate, blood pressure and other negative effects. Is that not true? Have you ever apologized to me for insulting me, posting negative comments about me on other websites, defacing my YouTube channel, and so on? 



"everyone's already heard about the rack of carving knives that careened about twenty five feet towards the coil. The coil was unaffected by the attraction."

I'll wager a cheezburger that you cannot demonstrate this. A rack of knives, "careening" about 25 feet towards the coffee-can sized coil, with the coil being "unaffected by the attraction". Let's see you demonstrate this. I think you won't, because you cannot.

You've made false claims and distorted and misrepresented many things before. Are you sure about what you are claiming now? PROVE IT.

[gyulasun]

...
An astute experimenter would measure the self-resonant frequency of his coil by looking for the maximum voltage swing, and then move on to this second test and do a full frequency sweep looking at the voltage and phase across the non-inductive resistor.  There may be some "surprises" to be found where there may be one or more "poles" and "zeroes" in the observed voltage and phase across the non-inductive resistor.

Yes, the Tesla bifilar coil construction can inherently give resonances at several frequencies and it is to be measured whether a parallel or a series resonance comes about at the first resonance frequency which is defined by the series connection of the two windings and the self-capacitance of the coil structure.
Here are two of  my earlier posts on this topic:
http://overunity.com/13460/teslas-coil-for-electro-magnets/msg360645/topicseen/#msg360645 and
http://overunity.com/13460/teslas-coil-for-electro-magnets/msg361749/topicseen/#msg361749 

The links do not work any more, unfortunately but on page 4 of this PDF file for instance the impedance curve is shown in the function of frequency:  http://www.ik4hdq.net/doc/testi/TrappCoassMulti.pdf
Here is a paper of a measurement setup http://www.iw2fnd.it/sites/default/files/docs/Trappole_01_EN.pdf

EDIT:  I managed to bring back my original link that was included in in my earlier post:
https://web.archive.org/web/20130321175122/http://vk1od.net/antenna/coaxtrap/index.htm  this includes further references and corrections to earlier studies

Gyula