profile paper explanation

[Terry Fritz <twftesla-at-xxxxxxxxxx>]

Hi Stefan,

I use the equation (v = 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 = 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 = 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. 
>But I can't agree to the fit formulas. In case of the loaded 
>coil I get the following polynomial regression:
>   Y = 4,46146*X + 0,10594*X^2 - 0,00273*X^3
>(Y in Volts, X in inches). That's completely different from 
>Terry's formula (v = 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 
>    interturn voltage stress is between 1/3 way up and 1/2 way 
>    up the secondary. That's where most of the coils create 
>    shorted turns (if they do).
> 2) I compared it to a simple linear fit (Y = Ymax/Xmax * X).
>    The deviation to the original data is below 5% (except the 
>    first 5 inches of the coil, where it is not so important), 
>    so I think for all practical purposes it is sufficient to 
>    calculate the voltage rise as a linear one for simplicity. 
> 3) The real interturn voltage stress is max. 12% higher than 
>    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:  |
>  _/    .__|_|__.              beam.to/stk         |
> /_______\-|-|-/___________________________________|
>
> Famous last words:  Oh, a Tesla coil - I heard you
> can touch it without getting hurt ---> Zzzzzapp...
>
>
>-----Ursprüngliche Nachricht-----
>Von:	Finn Hammer [SMTP:f-hammer-at-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-dot-com/TeslaCoils/MyPapers/NSVPI/NVSPI.htm
>
>Als Word hier:
>
>http://hot-streamer-dot-com/TeslaCoils/MyPapers/MyPapers.htm
>
>Gruesse, Finn Hammer