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Re: Fried Caps? (fwd)



---------- Forwarded message ----------
Date: Thu, 25 Oct 2007 22:53:14 -0500
From: Drake Schutt <drake89@xxxxxxxxx>
To: Tesla list <tesla@xxxxxxxxxx>
Subject: Re: Fried Caps? (fwd)

Hi victor,

I looked up the specs on those caps that you have and they are metalized PP
which is less than desirable for tesla coil use.  I don't really know WHY
but I do know that film and foil caps are preferred to any sort of metalized
plastic.  I know somewhere online there is a list of "bad" capacitors to use
in an MMC, and these may be some of them.  I'm sure someone can explain
exactly why your cap failed but it's not me.

good luck,
Drake Schutt

On 10/25/07, Tesla list <tesla@xxxxxxxxxx> wrote:
>
>
>
> ---------- Forwarded message ----------
> Date: Thu, 25 Oct 2007 23:11:59 -0400 (EDT)
> From: Victor Valencia <victor_valencia2@xxxxxxxxxx>
> To: tesla@xxxxxxxxxx
> Subject: Fried Caps?
>
> Hi,
>
>   I have a pretty basic TC that I built
> a couple of years ago.  It worked great
> in the beginning but I am having issues
> with the Tank Cap.  Here are the
> design parameters:
>
> NST 12Kv, 30mA
> Spark Gap: copper tube-based, 9 gaps with @20 mils/gap
> Tank Capacitor: 77x GE 42L 3kv, (7 strings of 11 caps) (.0066 uF total)
> Secondary Coil - 3.25" diameter, 801 turns 24 awg wire
> Top Load: 4.5" diameter aluminum ducting. total dia = 15"
>
> The problem I am having is that random capacitors just seem
> to heat up, melt, and/or catch on fire (lovely show, pic
> attached)
>
> Should I reduce my gap?  I thought that a 12kv
> input with 33kv for each cap string would be enough of
> a safety factor.  Is there some minimum spacing
> I should keep between the adjacent capacitors and/or
> the caps in the next string?
>
> Victor
>
>
>
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