From: "Tesla list" (by way of "Terrell W. Fritz" )
Date: Fri, 17 Nov 2000 19:25:15 -0700
Subject: [TSSP] profile paper explanation
Original poster: Terry Fritz
Hi Stefan,
I use the equation (v =3D 0.95 x + 0.35 x^2 - 0.29 x^3) in E-Tesla6 and I
"normalized" v and x in it. So the x and v values all go from 0 to 1. I
didn't make that clear in the paper. So for a maximum voltage of 100 volts
over 50 inches, the equation would become:
v =3D 100(0.95 x/50 + 0.35 (x/50)^2 - 0.29 (x/50)^3)
Or if L is the coil's length an Vmax is the top voltage:
v =3D Vmax(0.95 x/L + 0.35 (x/L)^2 - 0.29 (x/L)^3)
I suspect those equations may vary a bit for different height/width ratio
coils, but that's the best information I have at the moment.
Cheers,
Terry
At 02:08 PM 11/17/2000 +0100, you wrote:
>Hi Finn, Terry,
>
>Great! A good example of the 'flying capacitor method' used in
>some ICs.=20
>But I can't agree to the fit formulas. In case of the loaded=20
>coil I get the following polynomial regression:
> Y =3D 4,46146*X + 0,10594*X^2 - 0,00273*X^3
>(Y in Volts, X in inches). That's completely different from=20
>Terry's formula (v =3D 0.95 x + 0.35 x^2 - 0.29 x^3) which gives
>negative values for y ???
>
>Anyway, I used my formula and tried to do some more math:
> 1) I differentiated the fit and found that the maximum=20
> interturn voltage stress is between 1/3 way up and 1/2 way=20
> up the secondary. That's where most of the coils create=20
> shorted turns (if they do).
> 2) I compared it to a simple linear fit (Y =3D Ymax/Xmax * X).
> The deviation to the original data is below 5% (except the=20
> first 5 inches of the coil, where it is not so important),=20
> so I think for all practical purposes it is sufficient to=20
> calculate the voltage rise as a linear one for simplicity.=20
> 3) The real interturn voltage stress is max. 12% higher than=20
> the linear model will predict.
>
>So the "linear people" got right and I have to rework my
>website now :-(
>
>Again, great work, Terry!
>
>
>CU, Stefan
> _ _ _/_______________________
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> _ __// |_| _ |
> _// ` |_| ` Stefans Tesla coil pages: |
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> /_______-|-|-/___________________________________|
>
> Famous last words: Oh, a Tesla coil - I heard you
> can touch it without getting hurt ---> Zzzzzapp...
>
>
>-----Urspr=FCngliche Nachricht-----
>Von: Finn Hammer [SMTP:f-hammer@post5.tele.dk]
>Gesendet am: Donnerstag, 16. November 2000 22:05
>An: GermanTeslaList
>Betreff: GTL: neue data ueber secondaer spannungs profil
>
>Leute!
>
>Terry Fritz hat eine neue, einfach, und deshalb geniale methode
>ausgedacht, die spannungsprofil die secondaer spule zu messen.
>
>Im html, hier
>
>http://hot-streamer.com/TeslaCoils/MyPapers/NSVPI/NVSPI.htm
>
>Als Word hier:
>
>http://hot-streamer.com/TeslaCoils/MyPapers/MyPapers.htm
>
>Gruesse, Finn Hammer
Maintainer Paul Nicholson, paul@abelian.demon.co.uk.