Tesla's "COIL FOR ELECTRO-MAGNETS".

[gyulasun]

Multifilar pancake inductances, from 3zdayz:

http://www.youtube.com/watch?v=AQi-5xSeP_U

Published on Mar 30, 2013A bi-filar is definatly more inductance than a single.  As a motivator (generating a magnetic field) it is a more noticable field.
.... snip....

Synchro1,

(This post is a bit long, please take your time to digest it fully before name calling.)

I cannot help but notice that while it is true when you connect two individual coils in series their inductances add (like in case of two series resistors the resistances add) BUT if the coils have magnetic coupling between each other, then you have to consider the mutual inductance between them too. This means that the flux coupling can increase or decrease the resultant series inductance with respect to any one of coil values.

So when 3zdayz makes a bifilar pancake coil and measures its total inductance (in his video above at 1:56) to be 0.145 - 0.146 mH and then measures the "half" winding of it to be 0.043 mH (and measures the other half winding of it also 0.043 mH) and he says they together should be 0.086 mH (0.043 + 0.043=0.086), THEN he is mistaken because due to the close magnetic coupling between the two "half" windings the resultant inductance must be higher than the algebraic sum of them when the two windings are in series aiding connection.

Before you call me a MIB agent or stupid or hottentota, please study this link on mutual inductance between two magnetically coupled coils: http://www.electronics-tutorials.ws/inductor/mutual-inductance.html  and their resultant inductance in series when there is magnetic flux coupling between them:  http://www.electronics-tutorials.ws/inductor/series-inductors.html  Depending on how close you position the coils to each other and how the flux of any one coil can aid or repel that of the other, you can receive a widely varying result.

These are facts, I myself actually measured (years ago) bifilar, trifilar and quadrifilar coils' resultant inductances with an L meter when any of these were connected in series aiding. So I agree with the measurements 3zdayz shows with his L meter, right?

In theory, when there is say a perfect magnetic coupling in a bifilar coil, the inductance can be maximum 4 times as high in series aiding connection, than any one of the "half" windings has individually. Mr 3zdayz correctly measured his bifilars etc as I mentioned above, my problem is he expected the sum of the individual windings, just like you expected or accepted.
His individual windings in the bifilar were 0.043 mH each and in series aiding they gave 0.145 mH, (this shows the magnetic coupling between them was not 100% perfect, had it been perfect, the resultant series inductance should have been 4 x 0.043=0.172 mH.)
For another pancake coil of his, he measured 0.056 and 0.058 mH for the individual windings in a bifilar coil and in series aiding connection he got 0.224 mH (he wrongly expected 0.114 mH).

For a trifilar coil the series aiding connection would give 9 times as high inductance than any one of the 3 windings and for a quadrifilar coil the series connection would give 16 times as high inductance than any one of the 4 windings.

To understand this, take the bifilar coil example: suppose any one of the "half" windings within a bifilar has say 200 turns. When you connect them in series you will have 400 turns instead of the 200, and for any coil (not only for bifilar ones) when you double the number of turns (i.e. you continue winding to have 400 turns instead of the 200) the inductance increases to 4 times as many as it is with the 200 turns, ok? (The relationship between the coil inductance and the number of turns is quadratic, provided a close magnetic coupling exists between the total number of turns to approach the maximum 4 times, 9 times, 16 times etc theoritical upper inductance limit.)

NOTICE 1
I do not say a bifilar, trifilar etc coil cannot have any other, useful properties under certain circumstances versus a single wire coil, right? An example is just the Tesla patent Coil for Electromagnets when a bifilar is driven with a resonant frequency AC current.

NOTICE 2
When you compare a single wire coil to a bifilar coil and both the single and bifilar coils have identical wire lengths then you can measure nearly the same inductance for either the single or the bifilar coil (this latter is meant to be connected in series aiding). So from inductance point of view there is no difference between them, this means under a static electromagnet operation they perform identically (I repeat again: when their wire length is identical). 
This means that the first sentence in 3zdayz's quote above: "A bi-filar is definatly more inductance than a single."  is correct only when the bifilar coil is made from a longer wire length than the single wire coil. In case you happen to be in correspondance with him, please forward this fact to him.   

Gyula

[gyulasun]

Temporay permenant core magnetization delays the change in output coil pole shift, and retards the timing by creating magnetic field interference. My placement of permanent diametric magnets in SBC output coils  has produced the same AUL.

@gyulasum,

"your making a permanent magnetization for the core of an electromagnet in the nail core test is just ridiculous".

I uploaded a video demonstrating 2x the magnetic attraction with the SBC. How do you explain that?

Synchro1,

This is why I asked you to measure your battery voltage when your nail cored single or bifilar coil is connected to it but you refused.  I wanted to know how much Amper may have been drawn from your battery by the coils.

If you are willing to answer, could you tell how long you connected your nail cored coils (shown in your video) to the battery, to make them magnetized?  Did you measure the time for both coils case?  This is also important to answer your above question.

Gyula

[gyulasun]

...
I think the key word is "assumed",  in that context it means "Taken on" as in [ aggregate ] or [ Total  number turns all together ] ect. So it means he is talking of the same amount of wire in both coils "total", each of the strands of wire in the bifilar coil is half the length of the single strand in the regular coil.
....

Hi Farmhand,

Thanks for taking your time to answer my question.  Yes, in the meantime I consulted also with other people (with "born" English knowledge)  and got similar interpretations. 

Greetings,  Gyula

[synchro1]

Synchro1,

This is why I asked you to measure your battery voltage when your nail cored single or bifilar coil is connected to it but you refused.  I wanted to know how much Amper may have been drawn from your battery by the coils.

If you are willing to answer, could you tell how long you connected your nail cored coils (shown in your video) to the battery, to make them magnetized?  Did you measure the time for both coils case?  This is also important to answer your above question.

Gyula

I'm not setup to make those kinds of measurements. A pico second pulse is all it takes to bring all the electron spins into alignment and permenently magnatize the iron ferrite. A permanent magnet is free energy compared to electromagnetic field. The SBC nail permenently magnetizes from the high voltage field collapse spike, and needs no further current. The permanent field is twice what the single wire electromagnet produces under power. Have you seen my Cook battery post above?.

[TinselKoala]

@Gyula: Excellent post, and completely correct of course.

@MH: Here's an article that may be of interest.

http://mwrf.com/systems/standardized-approach-feeds-wireless-power

Note the construction of the transmitter coil that is described down the page. It's a 2-layer flat pancake coil-- essentially achieving the same effect as a series bifilar but in a smaller footprint.

And some low-frequency transmitting coils-- big coils in resonance --

http://lualualei1959.com/lowfreq2.htm