Re: [TCML] predicting phase shift

["Carey T. Waldrop" <cadredesign@xxxxxxx>]

Thank you Phil!

These exchanges are getting more than tiresome, they're aggravating!
Let's hear some constructive dialog between participants. I find that
there is alot of good information being exchanged here. Let's not get
bogged or "blogged" down in petty finger pointing and continue with
the inspiring discussions.

Cadre Design


----- Original Message ----- 
From: "Phillip Slawinski" <pslawinski@xxxxxxxxx>
To: "Tesla Coil Mailing List" <tesla@xxxxxxxxxx>
Sent: Thursday, June 25, 2009 4:36 PM
Subject: Re: [TCML] predicting phase shift


DC Cox,

You have been rambling on about how Finn Hammer's "Hammertone
Predikter" does not work for the past three days.  During this time
you have provided no real evidence that the circuit does not work.  At
this point you are beginning to sound like a broken record; you keep
restating the same "theories" over and over.  Finn has provided plenty
of evidence that his circuit works.  It would appear that most of the
coiling community agrees with his conclusions.  I am sure others will
soon repeat his experiment and obtain the same results.

I invite you to build the circuit exactly as Finn did and provide the
group with some real evidence that this circuit does not work.  Up to
this point you have proved nothing to the community except that you do
not understand fundamental concepts like inductance.  In the words of
Carl Sagan, "Extraordinary claims require extraordinary evidence."  If
you are going to continue to make such extraordinary claims about the
"Hammertone Predikter" please have the evidence to back these claims
up.

-Phillip Slawinski

On Thu, Jun 25, 2009 at 13:44, DC Cox<resonance@xxxxxxxxxxxx> wrote:
> Yes and no. You do have to worry about it in the case of DRSSTC circuits.
>
> In the case of a classic coil if the frequency shifts a bit as power
> produces thermal effects in the secondary coil, I agree, no problem. The
> spark gap jitter alone produces more off resonant
> firings than any thermal freq shift in the sec coil as it heats up during
> operation.
>
> But in these DRSSTC circuits even small changes in the tank capacitance
> value or in the thermal effects changing the resistive component in the 
> sec
> coil, yes,
> the coil will slightly change inductance and hence frequency, especially
> resonant frequency. Firing at exactly the zero crossing point is critical
> if you don't want to heat up
> the IGBTs.
>
> If the primary isn't firing very close to the zero crossing point heat 
> will
> be produced in the IGBTs which will lead to failure. You can NOT do it 
> will
> passive components. You need an active system to track the primary and sec
> currents.
>
> If you do a complex nodal analysis you can add in the thermal effects and
> then you will see the zero point shift within the time domain.
>
> Dr. Resonance
>
>
>
>
> On Thu, Jun 25, 2009 at 9:25 AM, <sparks@xxxxxxxxxxxxxx> wrote:
>
> > > Inductance can change with frequency. If you measure a coil at say
> > > 100GHz you will get some odd readings. But in our case at
> > > say 100kHz, you just don't have to worry about it.
> >
> > The inductance of an air core coil seems to change as the frequency is
> > varied, but this is due to errors in the measuring instruments and the
> > parasitic capacitance across the inductor. Iron core coils will show
> > different inductance values at different frequencies because the
> > magnetic properties of the core are slightly different at different
> > frequencies. Skin effect at high frequencies and current crowding at
> > high current levels will also change the apparent inductance of the
> > coil. All of these effects have been well documented in the literature.
> >
> > 73,
> >
> > Ralph W5JGV - WD2XSH/7
> >
> > _______________________________________________
> > Tesla mailing list
> > Tesla@xxxxxxxxxxxxxx
> > http://www.pupman.com/mailman/listinfo/tesla
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