Joshua,
The voltage gain in a Tesla Coil is a ratio of either the inductance of L1
to L2, or the capacitance of C1 and C2.
https://wikimedia.org/api/rest_v1/media/math/render/svg/0e212023a432b67ae4a3174efd65e30802af3428
As you can see, if you add more capacitance to the secondary circuit, the
voltage is reduced.
However, spark production is not all about voltage, you do need ample
capacitance. That capacitance is achieved through the discharge terminal,
which is typically a toroid or sphere. In practice this is a nice setup as
the large smooth radii of the shape provides a higher break out voltage and
yields (hopefully) the right amount of capacitance for nice spark output.
Additionally, without a decent size/shape discharge terminal, unwanted arcs
will appear at the top of the secondary. I also have to believe that adding
this type of capacitance would be considered parasitic, much like the self
capacitance of L2 (which is unwanted inefficiency).
So can you add capacitance in series with L2 and the ground? Yes. Will it
change Fres? Yes. Could you tune a coil this way? Yes...but this is really
impractical. Aside from finding a capacitor to withstand that environment,
it would probably be expensive...but also you would need a bunch of them in
infinite capacitances to re-tune with any accuracy.
A far easier and simpler solution is to tap the primary. You can move the
tap 1/4" inch at time to finely tune your coil to the exact frequency for
free and it is infinitely adjustable.
You might want to look up "tesla coil counter poise ground"...that would be
a related idea to what you are asking about...
~Dan
Kansas City area
On Tue, May 24, 2022 at 6:20 PM Joshua Thomas <joshuafthomas@xxxxxxxxx>
wrote:
> While playing around in JavaTC, I realized that the overall capacitance of
> the secondary coil (and hence Fres) could be modified by placing a series
> capacitor between the coil and ground.
>
> Tuning seems to usually be done on the primary coil by tapping, but this
> also seems an option. Has this been tried, and what results/caveats were
> there?
>
> Thanks,
> Joshua
>
> --
> Joshua Thomas
>
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