# RE: Capacitor matched size

```Within reasonable limits, _any_ capacitor value will ring up to dangerous
levels if the gap is set too widely, it need not be close to being the
so-called "matched" value.  True, a matched cap WILL allow the highest
ringup value, but something will probably arc out before that point is
reached.

Please allow me to correct a common misunderstanding.  Using DC will provide
no advantage as far as efficiency goes.  If a capacitor in an AC-powered
system is sized such that it charges to gap firing voltage in 1/3 of the
half-cycle, the remainder of that half-cycle is not wasted.  The gap will
dump the energy after the first 1/3 cycle, then the cap will charge again
and the gap will fire again.  This may or may not happen a third time in the
half-cycle.  Assuming that it does not, it is important to understand that
this last 1/3 half cycle is not wasted either.

Let's say that the gap firing voltage is 20KV, and during the last 1/3
half-cycle, the cap only charged to 19KV.  Now the cap begins charging in
the opposite direction.  However, that 19KV is not wasted, but it's energy
is transferred to current in the NST secondary, and the downward charging
will occur even faster.  So while the first half-cycle had only two gap
firings, the second half-cycle will have three or more gap firings.

Please see this illustrated on my web site at:
http://people.ne.mediaone-dot-net/lau/tesla/gapsim.htm

Regards, Gary Lau
Waltham, MA USA

ps - I messed up the waveform graphics slightly on this page last night.
Still viewable, but I'll try to fix them tonight.

>> Hi Kamil ...
>>
>> if you design the cap to be resonant with the power supply you run the
risk
>> of ring up in the tank circuit if the gap doesnt fire correctly     it is
>> better to go to the higher side when designing the cap system     this
way
>> you will be LTR and in a safer zone as far as over volting the cap if the
>> system decides to ring up on you...
>>
>> Scot D

>Original Poster: "Kamil Kompa" <czlonek-at-polbox-dot-com>
>
>You suggest me not to use resonant rise effect and make larger
>capacitor.
>Pherhaps the best solution is to use DC power to load the capacitot.
>Than I will be able to load any size of the cap (for example only 50 BPS
>but larger cap and of course larger energy stored and transferred to the
>secondary
>of TC). I think this solution also not allows to waste energy (when
>the capacitor is not exactly the size that is loaded in 1/2 or 1/4 or
>1/6 ... cycle)
>For example when the cap is loaded in 1/3 cycle enough to enable the gap
>to fire ,
>only 2/3 power will be transferred to TC.
>Is it worth effort to make DC power supply ?

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