Re: [TCML] predicting phase shift

[DC Cox <resonance@xxxxxxxxxxxx>]

Build it and then comment on it.

Dr. Resonance




On Thu, Jun 25, 2009 at 1:36 PM, Phillip Slawinski <pslawinski@xxxxxxxxx>wrote:

> 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
> >>
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