Re: Primary Resonant Frequency question . . .

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Daniel McCauley by way of Terry Fritz <twftesla-at-qwest-dot-net>" <dhmccauley-at-spacecatlighting-dot-com>


> > I've measured the resonant frequency of my secondary / toroid assembly
and
> > it turns out to be 195 kHz which is much lower than what i calculated in
my
> > designs.  Using tesla coil cad program, it says with my current primary,
i
> > should be tapped between turn 13 and 14 using a NST of 15kv/60mA, a
0.0106uF
> > capacitor at 195kHz.  Basically, this says i'm screwed, because in my
> > original calculations the resonant frequency was around 225kHz and
needed to
> > be tapped between turn 10 and 11.  I'm screwed because i only have 12
turns
> > (oops . . . ) of my primary.
>
> Top loads will "always" lower the resonant frequency of the secondary. The
> toroid should always be accounted for
> regardless of what program your using (including hand calcs). Your in
luck!

Actually, my original calculations took the toroid into account.

> The "main" components (LC) for the secondary are contained in the winding
> and geometry. Obviously, adding or
> removing turns will change the frequency. External to the secondary is the
> top load. Change it's size or position
> and you change the resonant frequency to some degree. This is why the
> primary is typically built with a few turns
> more than needed to account for various influences.

Yeah, I know.  The real problem in the beginning was i screwed up in
building my table so it was smaller than expected which
means less turns - i originally wanted 15 turns, but after calculating my
secondary resonant (using seconday dimensions and the 5" x 20" toroid), it
appeared i was okay with the smaller number of turns.  Well, we'll find out
when i turn it on for the first time.



> Take care,
> Bart
>
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