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Re: [TCML] capacitance and efficiency questions
If you multiply the JAVATC results by 60% it will be accurate, especially
with this very small coil dia.
Going up to a 6 or 8 inch ID pvc tube will increase your sec potential by
nearly 800% or more. The small dia is killing your -L x dI/dt where L
(inductance) is dependent on the square of the sec coil's radius.
With this size dia coil 70-75% x JAVATC predicted output is normal.
On Sun, Jun 22, 2008 at 12:40 PM, Kris Grillo <kristianisawesome@xxxxxxxxx>
> I have been reading over Ritchie's site, particularly the section on rotary
> gap analysis for internally shunted supplies. In the section on choice of
> primary tank capacitance, the equation is given, Cp = 150xCmatched/BPS. What
> does the 150 figure represent?
> I ran the numbers for my 9000V 90mA NST with a 120BPS sync rotary through
> this equation. The capacitance came to 33.125nf. This is much different than
> the figure acquired from JavaTC and from the 2.5xCres suggestion. I assume
> the larger capacitance suggestion is to load down the transformer and to
> minimize voltage stress on the cap and transformer. Is there a point where
> increasing the cap size is counterproductive to arc production?
> I have been running my 2" diameter twin coil at 60nf and I am only getting
> approximately 20" arcs from either side. JavaTC calculates arc length to be
> a little more than 40". I think someone mentioned that this figure should be
> 1.4x greater with the bipolar setup, so 56" or 28" per side is what I was
> expecting. Does this sound right? If so, where is the remainder of the
> energy being spent? It seems the rotary gap should be more efficient than
> that. Is 1/8" copper tube not adequate for the primary wiring in this
> system? Would lowering the Cp value help reduce the inefficiencies? Is the
> relatively low 9000V input adding that much to the gap's inefficiencies?
> Thanks for your help, guys. I know there are a lot of questions in this
> message, but I really am starting to understand this stuff better.
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