Joule Thief

[gnino]

http://youtu.be/ff3gRLpEC5g
In the video im increasing and decreasing power supply Voltage to have with both coil same ammount of light in the bulb
For now the Only benefits of the multifilar coil seems to be Wind more
Turn in less time

Ciao Luca

[TinselKoala]

http://youtu.be/ff3gRLpEC5g
In the video im increasing and decreasing power supply Voltage to have with both coil same ammount of light in the bulb
For now the Only benefits of the multifilar coil seems to be Wind more
Turn in less time

Ciao Luca

Don't worry about your English, it is fine. I understand you better than I understand many speakers of English as first language! You are getting your thoughts and ideas across very well, at least I think so.

You aren't seeing the benefit of Tesla bifilar windings because the true Tesla design depends on carefully winding the coil so that the turns are closely parallel, evenly and tightly spaced, and carry large voltage differences between the closely spaced turns. You are winding multi-strand coils but they don't qualify as Tesla bi- or multi- filar because they don't have the increased inter-turn capacitance of the Tesla system.

If you take a ferrite rod and a double-wire, wind a single careful layer with the doubled wire, then connect the far end of one of the wires to the near end of the other, you will then have a true "tesla bifilar" winding (although he used air cores). Each turn of one wire is between two turns of the other wire, and the voltage difference between the adjacent windings will be higher than between the turns of a single wire winding. This means increased capacitance between the windings and more energy storage in the coil during its oscillations. You should notice a difference then. (Ignore the green wire in the image below, it is a "primary" and is not bifilar-wound.)

[MileHigh]

TK:

You have to be very careful about what can be claimed with a Tesla "bifiler" coil.  I actually don't like calling it a bifilar coil because it only has two terminals.  I will use the term in this posting.

For starters, for a bifilar coil, the amount of potentially stored capacitive energy compared to the stored inductive energy for an imagined typical initial set of conditions is minuscule.  There amount of stored capacitive energy might be say on the order of 10^-5 joules whereas the inductive energy might be on the order of 10^-1 joules.   So with one ten-thousandth of the capacitive energy compared to inductive energy, it will be very hard to see and will not affect the typical operation of a typical coil.

Note also that this stored capacitive energy is fleeting and to really get a sense of what happens you would have to model it as a transmission line and do frequency and transient analysis in a massive CPU crunching party.

With respect to a JT, the coil does a pure inductive discharge into a "resistive" load, the battery.  So you don't have any kind of ring-down energy at play here.  You have what looks like a standard exponential decay of the current flow into the battery but it's not exactly an exponential decay.

Looking at the clip, and the size of the toroids and the windings, even a very neat bifilar winding would have a very very small transient capacitance value.  If you disconnect the "mid return point" and turn it into two separate wires and then hook up a capacitance meter to the two separate wires, you would be lucky if you measured a hundred picofarads.

I view the Tesla bifilar coil as an interesting effect with respect to the self-resonance of an abruptly disconnected coil.  We saw it in your early MHOP clips for a regular coil.  But I can't envision a real-world application for one.  Yes I am really down on Tesla bifilar coils (and I have taken flak for it.)

Gnino did not see any difference when he compared the two coils which is as expected.  The idea of going Tesla bifilar in a JT circuit doesn't make sense.  I give Gnino credit for doing an A-B comparison test between a regular coil and a bifilar coil with the same number of turns and build construction.  That's what anyone experimenting and testing for any possible or alleged benefits or advantages should do.

The bottom line is that Tesla bifilar coil configurations may be a questionable solution looking for a question and an answer.  I would love to see anybody do an A-B comparison test on any circuit where they can clearly show some tangible and measurable benefit from a Tesla bifilar coil with measurements.  I have seen many clips where people use Tesla bifilar coils in their experiments by rote, they are just doing it because they believe that they are supposed to be doing it.  It's akin to the "fancy geometry" coils that you see being used as the drive coils in pulse motors.

MileHigh

[TinselKoala]

TK:

You have to be very careful about what can be claimed with a Tesla "bifiler" coil.  I actually don't like calling it a bifilar coil because it only has two terminals.  I will use the term in this posting.

Have you actually read Tesla's patent 512340? perhaps you should, so that we are talking about the same things.

For starters, for a bifilar coil, the amount of potentially stored capacitive energy compared to the stored inductive energy for an imagined typical initial set of conditions is minuscule.  There amount of stored capacitive energy might be say on the order of 10^-5 joules whereas the inductive energy might be on the order of 10^-1 joules.   So with one ten-thousandth of the capacitive energy compared to inductive energy, it will be very hard to see and will not affect the typical operation of a typical coil.

Again, you are attacking a straw man that you have constructed yourself. Please read the patent.

Note also that this stored capacitive energy is fleeting and to really get a sense of what happens you would have to model it as a transmission line and do frequency and transient analysis in a massive CPU crunching party.

This is true. Analyzing TCs as lumped rather than distributed inductances and capacitances leads to incorrect conclusions.

With respect to a JT, the coil does a pure inductive discharge into a "resistive" load, the battery.  So you don't have any kind of ring-down energy at play here.  You have what looks like a standard exponential decay of the current flow into the battery but it's not exactly an exponential decay.

Looking at the clip, and the size of the toroids and the windings, even a very neat bifilar winding would have a very very small transient capacitance value.  If you disconnect the "mid return point" and turn it into two separate wires and then hook up a capacitance meter to the two separate wires, you would be lucky if you measured a hundred picofarads.

That's right, for the kinds of strawman coils you are talking about, which include the randomly wound multistrand coils that many people call "bifilar". These are not Tesla bifilar coils, though.

I view the Tesla bifilar coil as an interesting effect with respect to the self-resonance of an abruptly disconnected coil.  We saw it in your early MHOP clips for a regular coil.  But I can't envision a real-world application for one.  Yes I am really down on Tesla bifilar coils (and I have taken flak for it.)

Perhaps that's because you, like many people, have not actually read or understood Tesla's patent.

Gnino did not see any difference when he compared the two coils which is as expected.  The idea of going Tesla bifilar in a JT circuit doesn't make sense.  I give Gnino credit for doing an A-B comparison test between a regular coil and a bifilar coil with the same number of turns and build construction.  That's what anyone experimenting and testing for any possible or alleged benefits or advantages should do.

Perhaps.... Gnino did that test because I told him that his coil was not really a "bifilar" coil in the Tesla sense, that a TBFC was the only kind of "bifilar" coil that would have different effects, and how and why, and because I suggested the comparison test to him so that he could see for himself. Perhaps.

The bottom line is that Tesla bifilar coil configurations may be a questionable solution looking for an answer.  I would love to see anybody do an A-B comparison test on any circuit where they can clearly show some tangible and measurable benefit from a Tesla bifilar coil with measurements.  I have seen many clips where people use Tesla bifilar coils in their experiments by rote, they are just doing it because they believe that they are supposed to be doing it.  It's akin to the "fancy geometry" coils that you see being used as the drive coils in pulse motors.

MileHigh

People seem to expect all kinds of things from multi-strand coils, that is certainly true. In Telsa's day, as I have said many times, external HV capacitors were large and bulky and expensive and difficult to make. By building in extra capacitance in a _flat bifilar primary coil carrying high voltage high frequency pulsations_ the need for external capacitors is reduced and the effect of the coil's self-inductance on the speed of voltage transitions is reduced. Nowadays we can make HV/RF caps a lot more compact and cheaply so the added hassle of making a _real_ Tesla bifilar primary is seldom really beneficial: we just add more external capacitance instead and achieve the same practical result.

I have even seen people claim that a TBFC has zero inductance, which is a great misunderstanding and is why I always make the point that there are two common "bifilar" windings: the hairpin, which does indeed cancel inductance and results in a near-zero value, and the true TBF winding which still has practically the same inductance as a straight winding. But at the right frequency and voltage, a true TBFC nearly cancels its self-inductance and winds up looking like a "pure ohmic resistance" to use Tesla's own words.

Surely you have seen my videos where I compare the performances of flat coils wound with the same amount of wire, in both TBF and straight winding styles. When tested properly the difference is clear, even for my relatively tiny, relatively low voltage coils. Whether or not this clear difference is useful in any way, depends on what is done with the coils and the ingenuity of the experimenter. The difference, in a properly constructed TBFC, is clear, though.

http://jnaudin.free.fr/gegene/images/00512340.pdf

[MileHigh]

TK:

Of course I read the patent.  "Bifilar" means two wires, and four terminals.  The Tesla bifilar has one wire and two terminals.

There is no strawman in comparing the relative energies at some nominal operating mode.  The adjacent conductors in the wire are separated by the insulation and in terms of calculating capacitance that distance between the two "plates" is huge.  I am constructing a relatively simple model for the device.

Suppose the true pancake bifilar coil has an inductance of 300 milihenries.  It's just a guess for a typical flat pancake coil that someone might build with a diameter of say eight inches.  Then you look at the separation between conductors and check the relative permittivity of the wire insulation and simplify that as a long rectangular capacitor and punch all the numbers into a capacitance calculator and see what capacitance you get.  Then imagine the coil in DC resistive mode with one amp of current flowing through it and 12 volts across it.  So that means the length of bifilar wire looks like a capacitor charged to 6 volts.  Crunch the numbers and calculate the inductive and capacitive energy stored and compare the numbers.  You should find a drastic difference in magnitudes between the two.

So when you go to disconnect the coil from the battery, the capacitance is so small that it would have to charge to insanely high voltages to soak up the inductive energy.  Of course what really happens is that the air turns into plasma and conducts away a significant amount of energy before the self-resonance can start taking place.  Even for very small coils this takes place.

The patent basically says that you can store more transient energy than a regularly wound coil because of the increased voltage across adjacent conductors.  It also says that at the resonant frequency the two reactances cancel out and the coil will look like a pure ohmic resistance.  This is a patent about the physical architecture of the coil itself and its electrical properties, which nobody can disagree with.  That's all fine and dandy, but then what?

That's right, for the kinds of strawman coils you are talking about, which include the randomly wound multistrand coils that many people call "bifilar". These are not Tesla bifilar coils, though.

I take it your point is that winding a conventional coil on a spool with a "Tesla bifilar" winding scheme is not a true Tesla bifilar coil because it has to be a flat pancake construction.  That's fine but then what's special about the pancake?  The patent doesn't say what's special about the pancake, but rather the drawing shows it as a pancake.  I wonder if there is a lot of wiggle room there an and you can do it on a spool also.

Perhaps that's because you, like many people, have not actually read or understood Tesla's patent.

That was after my comment suggesting that there was no real world application.  Can you suggest a real world application?

Perhaps.... Gnino did that test because I told him that his coil was not really a "bifilar" coil in the Tesla sense, that a TBFC was the only kind of "bifilar" coil that would have different effects, and how and why, and because I suggested the comparison test to him so that he could see for himself. Perhaps.

So you are saying a true pancake bifilar coil will have different effects?  Can you explain the what, how, and why?

People seem to expect all kinds of things from multi-strand coils, that is certainly true. In Telsa's day, as I have said many times, external HV capacitors were large and bulky and expensive and difficult to make. By building in extra capacitance in a _flat bifilar primary coil carrying high voltage high frequency pulsations_ the need for external capacitors is reduced and the effect of the coil's self-inductance on the speed of voltage transitions is reduced. Nowadays we can make HV/RF caps a lot more compact and cheaply so the added hassle of making a _real_ Tesla bifilar primary is seldom really beneficial: we just add more external capacitance instead and achieve the same practical result.

I made the point in another thread that you can connect a real capacitor to a coil and get a much more conventional LC resonator that will operate like butter.  I also view the architecture as a work-around for not having readily available high voltage capacitors.  For me that means you are back at square one.  Okay, so with a wiring architecture implementation you create a "better" capacitor inside the coil and you have an LC resonator.  Then what?  Do you see my point?  The patent was filed in 1893.  In the context of the times you could indeed take out a patent on an LC resonator.  But is there more to it than that?  I don't think there is.  I also know that the "spooks" for lack of a better term believe that there is something akin to a "hidden message" in this patent or it's one of many hidden message breadcrumbs that you need to collect and piece together to find the "real" Tesla technology.  I don't buy that.

Surely you have seen my videos where I compare the performances of flat coils wound with the same amount of wire, in both TBF and straight winding styles. When tested properly the difference is clear, even for my relatively tiny, relatively low voltage coils. Whether or not this clear difference is useful in any way, depends on what is done with the coils and the ingenuity of the experimenter.

I am sure I saw your clips a long time ago.  No doubt there is a difference.  But can we do anything useful with that difference?

There was a promising television technology from a few years ago call "SED."  The picture was awesome and the elusive black levels were _black_.   But it got wiped out because of the LCD-Plasma war and they could not possibly compete against the continuously eroding price of the two main technologies - but the picture was better than both.  It was a solution in search of a problem that the market decided wasn't really there.  I believe that 3D TVs are also going to croak but I am not following that in detail.  I see somewhat of an analogy to the famous Tesla bifilar coil.

MileHigh