Re: [TCML] VTTC-tuning. John got me started ;-)

["Dex Dexter" <dexterlabs@xxxxxxxxxxx>]

Yes,I'm not considering enviromental components.And that's the point.
If you know current through the inductor,or better said time and space current distribution across inductor, you can calculate top volts quite accuratelly without all that what Bart and you mention.
Problem is that we don't know preceisely that distribution,but can measure  just the bottom current of secondary.
Hence the aproximation.

Dex

--- comsciprof@xxxxxxxxxxxxx wrote:

From: "Dr. John W. Gudenas" <comsciprof@xxxxxxxxxxxxx>
To: Tesla Coil Mailing List <tesla@xxxxxxxxxx>
Cc:
Subject: Re: [TCML] VTTC-tuning. John got me started ;-)
Date: Fri, 3 Apr 2009 17:07:55 -0500

Dex
You are not considering environmental components that exist in our  
natural world that affect top voltage.
Humidity, atmospheric pressure. existing ion streams etc. as Bart said  
all affect top voltage.

Eliminate the complexity of a variable E field and accelerating charge  
and look at simple electrostatics.

If a VanDeGraff belt is charged at a fixed current and the charge is  
delivered to the top HV terminal, but the humidity is high and the  
charge leaks off faster than it is delivered the top terminal could be  
at zero potential.
While an obvious simplification, the effect is exists for RF coils  
only it is more severe. We don't live in a vacuum or sulfur  
hexaflouride.
John W. G.

John W. Gudenas, Ph.D.
Professor of Computer Science

On Apr 3, 2009, at 12:49 PM, Dex Dexter wrote:

> Hi Bart,
> No I don't think so.
> It doesn't depend on the temperature of the day,humidity,radius of  
> curvature etc.
> If you consider it more it is not the formula for the prediction.
> It is formula for calculation if you know secondary base current (or  
> given the current).
> That's the voltage developed across inductor.
> The only unknown thing is "L" which varies from design to design and  
> size of topload.
>
> Dex
>
> --- bartb@xxxxxxxxxxxxxxxx wrote:
>
> From: bartb <bartb@xxxxxxxxxxxxxxxx>
> To: Tesla Coil Mailing List <tesla@xxxxxxxxxx>
> Cc:
> Subject: Re: [TCML] VTTC-tuning. John got me started ;-)
> Date: Thu, 02 Apr 2009 19:02:36 -0700
>
> Hi Dex,
>
> Dex Dexter wrote:
>> 3.Is this a good formula to roughly estimate top volts:
>>
>> 0.5*L*di/dt < V < L*di/dt
>>
>> where i denotes secondary base current ,L low frequency secondary  
>> inductance,t time.
>
> When considering top volts, it is certainly a "rough" estimate. A
> calculation can tell you about where you would expect the top volts to
> "top out at". But the temperature of the day, humidity, radius of
> curvature of the top terminal, preceding ionization, etc.. will
> determine the actual breakout voltage and it can be drastically
> different than the calc. But yes, if you look at the peak base current
> (which is much higher than the average base current) and look at the
> current over time, you can calc the value at which the top load will
> attempt to charge to. But, in reality, it will likely break out at a
> lower voltage based on the misc. conditions described earlier.
>
> Personally for a top-volt guess, I use Vpri x sqrt(Cpri/Cee) * 0.7 and
> Cee comes from Javatc since Javatc has the ability to equate the  
> energy
> storage capacitance (that moment in the cycle when all the energy is
> stored in the capacitance of the top load).
>
> Take care,
> Bart
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John W. Gudenas, Ph.D.
Professor of Computer Science


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