Hi Conrad,

Thanks for showing the measurements on the two pancake coils. 

For me, a coil normally has a self capacitance (I prefer using this term instead of the interwire or parasitic capacitance),  represented as a parallel capacitance with the coil itself.  This is what defines the first parallel resonant frequency for a coil when you do not connect any tuning cap to it, just excite the coil in a circuit which adds no any other capacitor to the coil and look for the parallel resonance like this link shows here:
http://www3.telus.net/chemelec/Calculators/Interwire-Coil-Capacitance-Calc.htm   

So I find it a bit unusual that the 'parasitic' capacitance values come out as 174pF and 229pF, while the interwire capacitance values come out as 7 and 44pF.  I will think this over how it could be explained, unless the measuring method for the parasitic capacitance inherently introduces some additional "error".

Could you measure the capacitance between any two wire ends of the bifilar coil?  Just do not couple or connect anything to it, and use your C meter between the two start wires or between the two end wires: possibly these two C values should be the same.  Practically you measure the capacitance between the two parallel guided insulated wires A and B.  (For all these C measurements you have to remove the jumper wire you use for the series connection of A and B wires/coil.)
Maybe you could check the C value between one start wire of coil A and the end wire of coil B too, (though I am not sure whether this C would be the same C as either the start or the end C value.)

Thanks,  Gyula

PS:  For you, the interwire capacitance and the parasitic capacitance mean a different capacitance? 

Conrad:

There is no true answer to your question about the "ideal" dimensions for a pick-up coil.  What I suggest that you do is that you make your two coils about fist-sized (you may have some empty plastic wire spools about that size?) and use a relatively small gauge of wire.  The reason that I am suggesting using a relatively small gauge of wire is to get a larger inter-filar capacitance so that you might have a chance of observing the effects of the capacitance in real-world tests (i.e.; not the self-resonance tests).

I will still pitch my "pet" concept:  You might get lucky and find some good wire on spools at an electronics hobbyist store.  Say you find a nice spool of 32-gauge single strand wire.  If you are really lucky you will find a very similar spool of 32-gauge speaker wire (two conductors).  So you make the simple connection with the speaker wire to create the bifilar coil.  If both spools have insulation that appears to be the same thickness and the same type of plastic then you will have two "instant coils," a regular monofilar coil and a bifilar coil.  If you are really really lucky you will be able to insert different core materials into the hollow centers of the plastic spools.

There is an interesting "Plan B."  Buy two identical spools of speaker wire.  On one of the spools do the bifilar connection.  On the other spool just use one of the two wires, or simply short the two parallel wires together at each end of the speaker wire to give you one-half of the resistance for the coil.  There is a distinct advantage to using light gauge speaker wire because the two conductors are held firmly next to each other by the plastic insulation.  The fact that the bifilar in this setup will have twice as many turns as either variation on the monofilar is irrelevant.  All that means is that the voltage output will be lower.  You have the choice of load resistor and can compensate.  The important thing is that the geometry will be the same.

The whole intention here is to hopefully give you a fighting chance to see _any_ capacitive effects for different types of real world tests.  Like I have posted many times before it's very unlikely that you will observe any capacitive effects from the bifilar coil because the inter-filar capacitance will be minuscule compared to the inductance.  Also, the capacitance is fleeting and trasient and only exists for perhaps a few microseconds before the "dead short" of the wire in the coil "destroys" it.  As far as the "fantastical" claims go for the bifilar coil go, you can expect to see nothing.

So don't worry, there is no "right" or "wrong" configuration for your coils.  Just make "sensible" coils that are sized in proportion to your spinning rotor magnet.

Good luck and have fun!

MileHigh

Conrad:

About getting the bifilar coil to self-resonate to the point where the voltage gets so high that the air starts to ionize:

You will not see the air ionizing effects with coils like this with your current setup.  You don't have the available power source.  However, you could still see similar effects.  For example you could have a small "exciter" coil that sits next to and is magnetically coupled to the bifilar coil.  Then you run a sine wave and sweep the frequency in the small exciter coil and observe the unloaded output of the bifilar coil in your scope.  You may see some peaks in the response of the unloaded bifilar coil.

This all sounds fine but there are problems.  The higher the frequency you put into the exciter coil (always use a sine wave on your function generator) the higher the impedance of the exciter coil.  So you have less and less "push" from the exciter coil as the frequency increases.  One possibility would be to connect your signal generator to an audio amplifier and have the audio amplifier drive the exciter coil.  If you are really lucky you might find a frequency that is a sub-harmonic of the self-resonant frequency of the bifilar coil that is below 20 KHz (within the bandwidth of the audio amplifier) and the voltage on the open-circuited bifilar coil will greatly increase and the air will start to ionize.  The key here is you need power.  The hope is that the audio amplifier has enough power to make the bifilar coil resonate at a very high voltage and you start ionizing the air.  You have to keep in mind that in that clip the guy is using a big powerful electric motor though.

Note it would still be a victory if you got the bifilar coil to resonate in sympathy with the small exciter coil to a very high AC voltage.  Something like this:  You pump 15.35 KHz into the exciter coil and you observe a peak in the response of the open-circuited bifilar coil at 122.8 KHz. (8X the exciter coil frequency).   So you have the exciter coil "ringing the bell" at 15.35 KHz and the bell rings at 122.8 KHz.  So you know that you are exciting the bifilar coil at one-eighth the natural self-resonance of the bifilar coil.

All of these types of experiments are experiments in the frequency domain.  Whenever you do these types of experiments you slowly sweep the exciter frequency from low to high and you observe the response in the device under test.  Normally you never see a sub-harmonic induce the device under test to resonate at it's natural frequency.  Rather, you will simply observe the same frequency at the output of the device under test but with a different amplitude and phase.  So you will have to get really lucky to get a sub-harmonic excitation inducing fundamental resonance in the device under test.

There is an interesting "kluge" for this.  Instead of a sine wave excitation try a square wave excitation.  With a sine wave you are only putting one frequency into the exciter coil.  With a square wave you are putting multiple distinct sine waves into the exciter coil.  One of the higher-frequency components in the square wave might "catch" the bifilar coil at the fundamental or at a sub-harmonic and get it to resonate at a very high amplitude.

http://en.wikipedia.org/wiki/File:Square_wave_frequency_spectrum_animation.gif

MileHigh

P.S.:  I must stress that you are reading educated guesses from me and some reasonable speculation.  I have tons of bench experience but it was a long time ago.  Also, these types of things are not discussed in "real life" in the world of electronics.  Perhaps they are effects that are considered and observed and dealt with in the realm of very high frequency analog radio circuits  (nothing to do with free energy).  I am just guessing because I have no experience there.  In one job I worked next to a radio engineer and observed him working on his bench and only spoke a bit about what he was doing.  So please take my comments about all of these ideas for tests and related stuff with a grain of salt.  Most of the bench type testing for "free energy" you see discussed here and on YouTube is only done in the realm of free energy enthusiasts.

http://www.youtube.com/watch?v=eC36AqL5mw8

Quote from: gyulasun on January 08, 2014, 06:08:38 PM

For me, a coil normally has a self capacitance (I prefer using this term instead of the interwire or parasitic capacitance),  represented as a parallel capacitance with the coil itself.  This is what defines the first parallel resonant frequency for a coil when you do not connect any tuning cap to it, just excite the coil in a circuit which adds no any other capacitor to the coil and look for the parallel resonance like this link shows here:
http://www3.telus.net/chemelec/Calculators/Interwire-Coil-Capacitance-Calc.htm   

So I find it a bit unusual that the 'parasitic' capacitance values come out as 174pF and 229pF, while the interwire capacitance values come out as 7 and 44pF.  I will think this over how it could be explained, unless the measuring method for the parasitic capacitance inherently introduces some additional "error".

Could you measure the capacitance between any two wire ends of the bifilar coil? 

@Gyula:

I though that parasitic, self and interwire capacitance are three different things. After some contemplation and looking around in the internet I agree, this is all the same. The "capacitance inherent to the coil" usually depicted and mathematically treated as a parallel capacitance to the coil (inductor) http://sine.ni.com/np/app/main/p/ap/mi/lang/de/pg/1/sn/n17:mi,n21:37/fmid/2914/.

I measured the capacitance between the two wires of my bifilar pancake coil (after opening the connection between the two wires).

It does not matter which ends of the wires are used for the capacitance measurement, the capacitance is 200 pF to 230 pF (varies if I measure with 100 Hz, 1 KHz or 10 KHz).

So it looks like this method http://www.qsl.net/in3otd/inductors.html is correct and that method is may be flawed http://www3.telus.net/chemelec/Calculators/Interwire-Coil-Capacitance-Calc.htm .

I will do some measurements with an "exciter coil" like in this video http://www.youtube.com/watch?v=BrY6Q4JCjXs (you called it "measuring resonance without any tuning cap"). The coil will resonate with the "self capacitance of my scope probe" (which is 85 pf - 115 pF).


@MileHigh:

Thank you for your explanations, it helps.

There are always more questions. Do you think that the core of the coil I want to wind should have a diameter of 25 mm, because the spinning magnet has a diameter of 25 mm? (I wanted to have a core of 10 mm, because I have a Ferrite which would fit.)

I understood that the diameter of the coil should be about the diameter of a fist, but I am now thinking about the diameter of the core (of the hole in the middle of the coil). This core could then be an "air core" or an "iron core" (if I put a bundle of iron wire sticks into it) or a "Ferrite core" (if I put my 10 mm Ferrite rod into it).

I could also make a "rectangular core" of 5 mm x 25 mm, because these are the dimensions of the spinning magnet.

Greetings, Conrad