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Re: Inductance of a conical coil
Original poster: "Barton B. Anderson by way of Terry Fritz <teslalist-at-qwest-dot-net>" <classictesla-at-netzero-dot-com>
Hi All,
I know some of you would rather run Fantc off-line (as I do most of the
time). To accommodate this, I've zipped up the new version and uploaded it
to a temporary directory for your download convenience.
To do this, follow these simple instructions:
1. Create a folder on your hard drive (might want to name it Fantc).
2. Download http://www.classictesla-dot-com/temp/fantc1.2.zip
3. Open the zip file and extract all it's contents to the new folder.
4. You can then simply run Fantc.html in your browser from your hard drive.
It doesn't get much easier. The zip file is 330k. The files unzipped are
530k (860 if you retain the zip file in the same directory).
Take care,
Bart
Tesla list wrote:
>Original poster: "Barton B. Anderson by way of Terry Fritz
><teslalist-at-qwest-dot-net>" <classictesla-at-netzero-dot-com>
>
>Hi Antonio,
>
>Yes, I remember the discussion. There was no solution posted. I believe we
>did agree the inverse conical equation popular was grossly in error.
>Following that discussion I took a look at it and found the error jumped
>all over the place with the angle.
>
>Here's the basic popular equation:
>
>Case 3: Inverse Conical Primary:
>
> / \
> -- o / o
> | o / o
> | o N turns / o
> o Z / o
> h o / o /
> o / o /
> | o / o / Angle = X
> | o \ o /
> -- o o ------------
> |
> | w | R | |
> |<-- W -->| ^
> Center | Line
>
> Z = Coil Width (hypotenuse length)
> X = Angle of Cone (versus horizontal plane)
> h = Z*sin(X) Effective vertical Height
> w = Z*cos(X) Effective horizontal Width
> W = R + w/2 Average horizontal Radius
>
>
> L1 = W2*N2/(9*W+10*h) (Vertical Inductance Component)
>
> L2 = W2*N2/(8*W+11*w) (Horizontal Inductance Component)
>
> L = SQRT[(L1*Sin(X))2 + (L2*cos(X))2]
>
>This formula weights the horz and vert Wheeler equations, but is poor in
>accuracy. I've added my own "weighting" to this of which the final L above
>is multiplied by a factor based on the angle.
>
>I then have:
>L = [SQRT[(L1*Sin(X))2 + (L2*cos(X))2] ] * my factor
>
>First I find the cosine and sine of the angle in radians and denote them as
>"sina" and "cosa". My factor is then: ((cosa^2+sina^2)/SQRT(cosa+sina))*2
>
>When applied to L as above, it results fairly decent, but of course cannot
>pull out Fantc accuracy for conical coils.
>
>Example: (inches)
>Angle = 20
>Inside Diam = 11.375
>Outer Diam = 30.223
>Outer Top Height = 3.43
>Wire Diam = 0.375
>Turns = 13.6
>
>Equation Outputs (uH):
>Cone Eq. w/factor Fantc
>113.93 100.64 101.63
>
>Note, Vert L1(vert) = 156.4 and L2(Horz) = 107.05.
>
>For reference: at 20 degree, sina = 0.939693, cosa = 0.342020. My factor
>then = 0.883292708 and this is what was applied to Cone Eq. of 113.93 to
>arrive at 100.64.
>
>That's how I worked around the error. Of course, we could just use Fantc
>and similar programs to find a better L, but for a
>quick-pop-in-a-spreadsheet equation, I've simply applied this factor.
>
>Take care,
>Bart
>
>Tesla list wrote:
>
>>Original poster: "Antonio Carlos M. de Queiroz by way of Terry Fritz
>><teslalist-at-qwest-dot-net>" <acmq-at-compuland-dot-com.br>
>>
>>Hi:
>>
>>I was reviewing the archives looking for a good approximate
>>formula for the inductance of a conical coil. There was a
>>discussion years ago, but didn't come to a conclusion. That
>>formula that makes an average between the Wheeler approximations
>>for solenoids and flat coils is very poor. The Wheeler formula
>>for flat coils is also poor.
>>What would be the best formulas now?
>>
>>By the way, I have added mutual inductance calculation to my
>>Teslasim design/simulation program.
>>http://www.coe.ufrj.br/~acmq/programs
>>
>>Antonio Carlos M. de Queiroz
>>
>>
>>
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