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Re: Beginners Tesla Coils
>Actually, I was thinking that an air capacitor might be the way to go
for
>my creation. I saw a picture of one on a web site and considered
several
>advantages; it might be possible to air cool the capacitor with a fan,
>more plates could be added as neccessary, and one could vary the
>capacitance by clipping the lead onto a different copper plate or
>altering the distance between the plates. What I'm running into is the
>obvious fact that so few people are using air caps. Can anyone fill me
>in on the disadvantages to this approach?
Air capacitors don't get very hot and really shouldn't need air cooling
untill you get to multi-kilowatt power levels. The reason is that the
dielectric air will just rise away from the plates if it gets hot.
Here are the main disadvantage: Air has a dielectric constant of 1.
Therefore an air capacitor will be 4 times larger than a glass one or
about twice as large as a PE cap (probably more since you can't roll it.
I'm not really sure about the losses of air in the RF range, but I'm
pretty sure they are higher than PE. Plus, making sure that the plates
are exactly at the same distance all around is quite difficult and you'd
need hard plates (steel) that would be much heavier than the aluminium
flashing all of us use (not to mention more expensive and harder to work
with).
So that's why not many people use them...
Hope it helped...
Sam Barros
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