# RE: [TCML] Is this right?

```Also, just as an aside...

Reading through his website -- there are a lot of simple typos and egregious
errors that should have been caught.

Lotz wire, Tom Ptiman (Pitman and actually, it was Robert Uterwick who did
the Tiny Basic for the SWTP Motorola 6800, Pitman did it for the Altair
8080)

I know that some SWL people are blind and I don't know if he has this
problem but if not, sheesh!

Dave

> -----Original Message-----
> From: tesla-bounces@xxxxxxxxxx
> [mailto:tesla-bounces@xxxxxxxxxx] On Behalf Of bartb
> Sent: Saturday, January 12, 2008 10:02 AM
> To: Tesla Coil Mailing List
> Subject: 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,
> 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
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> >
> >
> >
>
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