Re: [TCML] Reality or Artifact

[bartb <bartb@xxxxxxxxxxxxxxxx>]

Cool Matt, so you see the issue I was looking at. Sure, at DC low freq., 
the 0.45 works, but when we run at "whatever" freq our coils are at, the 
inductance at resonance is going to be a bit different. Kind of changes 
things. The Ldc curve flatness doesn't surprise me too much. After all, 
it's graduates up to it's max and then runs back down slowly. 
Interesting to me was how the high frequency inductance was not flat... 
fun stuff...

Take care,
Bart

mddeming@xxxxxxx wrote:
> Hi Bart, 
>
> Interesting charts. The Ldc peaks at ~0.42 close enough to the 0.45 of the quick and dirty, but Les peak is way off at 0.20.  Seems like a secondary coil with an h/d ratio of 0.20 would be highly impractical for most peoples' TC purposes: long sparks.  I was a little surprised that the Ldc curve was so flat. near the max value.
>
> Thanks for the info.
>
> Matt D.
>
>
>
>
>
> -----Original Message-----
> From: bartb <bartb@xxxxxxxxxxxxxxxx>
> To: Tesla Coil Mailing List <tesla@xxxxxxxxxx>
> Sent: Thu, Jun 3, 2010 9:35 pm
> Subject: Re: [TCML] Reality or Artifact
>
>
> Hi Matt, 
>  
> Lucky for you, I already performed that nasty daunting task ;-) . I went through Javatc and setup h/d ratios from 0.01 up to 1.0 in .01 increments, found max inductance and logged data. What I was looking at was the difference between low and high frequency inductance (Ldc, Les) and how they would track. 
>  
> Here's a graph of that endeavor 
> http://www.classictesla.com/temp/MaxL.gif 
>  
> The excel file is here with the data 
> http://www.classictesla.com/temp/max_inductance_csv.xls 
>  
> Not sure if this helps at all, but if so, great. 
>  
> Best regards, 
> Bart 
>  
> mddeming@xxxxxxx wrote: 
>   
> > Hi All, 
> >     
> > > In the classic, quick and dirty formula for the calculation of solenoid inductance, > > L=(Nr)^2/(9r+10h) > it can be shown with a little Calculus and Algebra that the maximum inductance for a given length of wire occurs when h=0.9r. This formula was originally derived, however, for "long" solenoids but the calculation results in what may be described as a rather "short" solenoid. The maximum may be an artifact of the approximation. Does anyone know the range over which the formula is valid and if there is an actual maximum at or near this ratio (h/d = 0.45)? If not, I suppose numerous iterations of Javatc could be plotted, but there again, what is validity range of Javatc's approximations? Perhaps the next step would be for me to bring the question to the "High-Mages" of TSSP. 
> > >       
> > Matt D. 
> >
> >
> >
> >
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