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Re: [TCML] Is this right?

Hi Ben,

Clarke is dead wrong. Clarke is saying that adding Ctop would increase Q and most "high school Tesla Coils" have a Q of 1. Both statements are completely wrong. If Clarke is thinking that adding Ctop decreases frequency which increases skin depth, and thus larger top load would have higher Q due to a lower frequency, then he's not really looked at the situation. The fact is, increased Ctop does reduce frequency, and due to that, skin depth is increased, but Q does not go up. In fact, it goes down.

Q is a ratio of the energy stored in the inductor of a coil divided by the energy lost per cycle. There are many mathematical representations for Q. One I prefer in Tesla Coils in particular is looking at the energy storage within the coil: Q = sqrt(L/C)/Rac. Note the sqrt(L/C) portion and note Rac. Clarke is looking only at Rac. It does in fact lower a little with larger Ctop (and someone could easily assume Q must then increase). But, sqrt(L/C) is a far more drastic change (due mainly to C which increases) and results in the Q actually decreasing with increased Ctop.

Many of us have made these measurements and Q's of 300 are easily achievable. Apparently Clarke has never measured Q of a Tesla Coil. I suspect he read some website somewhere making a statement of Q dropping during spark loading and then tried to put 2 and 2 together. Nice try but wrong.

Take care,

Ben Sneath wrote:
hello all,
i found the on the website:  www.prc68.com/I/electron.shtml
(if the link shows up)
...All of the above is very important since a coil operating
at it's self resonant frequency has a Q of 1, no matter how
it was made.  (This is something that 99.99% of the Tesla
coil builders don't get.)  So in order to get high Q you
need to load the coil with a capacitance that's
substantially larger than the self capacitance.   You can
see the it's very important to not only wind the coil in
such a way that the HF resistance is minimized but also in
such a way that the self resonant frequency is as high as

is this true? secondry with a Q of 1 no matter what when @
its res. frequency?????
if it is right then how does that happen??

BTW...why in older posts was the "." replaced with the word
"-dot-" in links?
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