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Author Topic: Investigating "anomalies" in Bifilar coils  (Read 151 times)
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Here some Odd behaviors of the bifilar coil will be investigated .

underconstruction
« Last Edit: 2017-04-21, 01:42:33 by Chet K »
   

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Believing something false does not make it true.
Typo in subject
"Bifiler" should be "Bifilar"

Is that an anomaly? LOL   ;D

 I wonder why for some of us that word is so hard to type correctly.  I find myself about half the time typing it with an "e" when I know it is supposed to be an "a".  Sometimes I catch myself and sometimes it is a day or so later before I see what I have done.  The human mind is a strange thing.



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Just because it is on YouTube does not make it real.
   
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well
I have a hard time reading and typing since the last eye surgery[last week] , and I'm a terrible speller anyway !!

Here some discussions will evolve around experiments which have shown anomalous behavior [or is it ?]

will take a few hours to get this sorted so it has a sense of direction, some of Partzman's earlier observations
will be discussed as well as wireless behavior and magnetic behavior of Bifilar coils ,and not just round coils.

 

   

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Well, as long as you aren't a terrible smeller, it should be OK !


Meanwhile, back at the ranch....


One Tesla Bifilar (TBF) flat coil as "primary" being fed with sinewave signal (Blue) from ElCheepo DDS FG at 10V p-p, through a 9.4 ohm precision noninductive resistor with a scope probe across the resistor (Yellow). One monofilar coil with same amount of wire and turns as "secondary" mounted co-axially about 1 cm away from "primary", used as sense coil, directly connected to scope probe (Purple).  One scope shot at 5 seconds/division horizontally, while FG scans across frequency range. (Two full 30 second scans shown.)  Another scope shot at the resonant frequency of the TBF coil. Both shots show that the voltage across the current-viewing resistor "flatlines" at the TBF coil's resonant frequency, which should mean that there is no current flowing. Right? Yet the voltage trace from the "secondary" monofilar pickup coil shows clearly that there is voltage induced in that coil. So there must still be a substantial alternating magnetic field happening in the TBF coil. Right?

« Last Edit: 2017-04-21, 05:08:54 by TinselKoala »


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"The easiest person to fool is yourself" -- Richard Feynman
   

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What is the ground lead of the blue probe connected to ?

So there must still be a substantial alternating magnetic field happening in the TBF coil.
...or alternating electric field.
   

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The "Blue" probe is a direct connection from the second channel of the DDS FG to the oscilloscope with a BNC patch cord. The first channel of the FG is connected by the red and black clips in the photo. While this FG has isolated "ground" the isolation is broken by making the connection to the scope with the BNC patch cord. So all channels of scope and FG share the same ground.

It's hard for me to see how either the magnetic or electric fields can be alternating so nicely when there is no current -- or more precisely voltage drop -- evident in the CVR. Unfortunately when the "secondary" pickup coil is loaded with, say, an LED, the TBF's CVR current trace no longer flatlines. It gets small and still is at minimum at the TBF's resonant frequency, but is definitely no longer at zero.

(I know the colors are actually cyan and magenta but on the live scope they look more blue and purple to me.)


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"The easiest person to fool is yourself" -- Richard Feynman
   
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It's hard for me to see how either the magnetic or electric fields can be alternating so nicely when there is no current -- or more precisely voltage drop -- evident in the CVR. Unfortunately when the "secondary" pickup coil is loaded with, say, an LED, the TBF's CVR current trace no longer flatlines. It gets small and still is at minimum at the TBF's resonant frequency, but is definitely no longer at zero.



Wonder if the coil is heating up,while there is no current flowing through it?


Brad
   
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TK,

If you would measure the inductance of just one of the bifilar windings in your TBP and also the capacitance between the windings, I would attempt a sim to see if the TBP is functioning as a cross coupled symmetrical transmission line as depicted in the attached schematic.

Regards,

PM

Edit: Added "cross coupled".
   
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