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, Bart 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 possible... 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? _______________________________________________ Tesla mailing list Tesla@xxxxxxxxxxxxxx http://www.pupman.com/mailman/listinfo/tesla
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