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Re: nonresonant cap = imcomplete charge ?



Original poster: "Terry Fritz" <twftesla-at-qwest-dot-net>

Hi Larry,

At 04:46 PM 10/21/2002 +0000, you wrote:
>Call me thick headed, but...
>I understand how a less than resonant cap
>(i.e. xfmr req 27.5nf and tank cap is say 12nf or some number below 27.5) 
>does not use all of the power of the xfmr energy.

Smaller caps can have higher break rates which can make up for the lower
energy stored in the cap.

>
>with a LTR cap, the energy from the xfmr charges the cap, and then
>there is still time left in the cycle that is not charging the cap.
>this equals less energy per bang.

LTR = Larger Than Resonant.  I think you mean STR = Smaller Than Resonant.

>
>but I've heard that (or maybe misunderstood) a GTR cap (as above xfmr
>req 27.5, tank is greater than 27.5, say 35nf)....
>so I've heard that a GTR cap is not as efficient as a resonant cap.
>it was stated that less energy is stored than a resonant cap.

There is no "GTR".  You mean LTR here.

>
>is it the impedance of charging of the capacitor? the charge rate of the 
>capacitor is not a straight line.  so it would then follow that if the 
>charge rate is not a line, that if a GTR cap contains less energy than a 
>resonant cap, then the average charging rate should be less than a resonant 
>cap compared to a GTR cap.
>
>am i on track or completely lost?

Your fairly lost ;-)

STR = Smaller Than Resonant.  These are caps that are small and charge very
fast.  They can have higher BPS (Breaks Per Second) but they are not
optimal.  STR size caps are popular with pole pig systems since there is
plenty of power to spare and they can run higher BPS rates.  The RMS
current stress on the caps can be very high in these systems.

Resonant size caps are sized to resonant with the transformer's output
impedance (usually NSTs).  These can be more efficient and usually run
about 200 BPS.  There is a big risk that if the gap fails to fire the
voltage will resonant up to about 80,000 Volts which will blow something up.

Static LTR = Static gap Larger Than Resonant.  These caps not only charge
the cap to voltage but also suck extra energy from the NST secondary stored
as current in the output inductance.  These are very safe in that the
voltage cannot go higher than the NST is designed for.  The value is pi/2
that of the resonant case.

Sync Gap LTR = Same as above but with sync gaps you can play timing tricks
to get full voltage on a cap that is pi times the size of the resonant cap.
 These are about the most powerful systems of all.  There is a chart of all
this at:

http://hot-streamer-dot-com/temp/MMCcapSales.gif

Also see details at Richie's site:

http://www.richieburnett.co.uk/tesla.shtml

Cheers,

	Terry


>thanks,
>larry.
>
>
>