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Re: MMC question (SMT cap comment)




-----Original Message-----
From: Tesla List <tesla-at-pupman-dot-com>
To: tesla-at-pupman-dot-com <tesla-at-pupman-dot-com>
Date: Tuesday, June 15, 1999 5:39 PM
Subject: Re: MMC question (SMT cap comment)


>Original Poster: Terry Fritz <twftesla-at-uswest-dot-net>
>
>At 08:33 PM 6/15/99 +0200, you wrote:
>snip...
>>Hmm, I have never seen SMD caps with a 500V or higher rating. The
>>biggest ones I have seen are rated at 100V and 220nF. These are
>>made from polyester and have a dv/dt of 35V/µsec. The test rating
>>(for 2s) is 350V/µsec. So, even if we neglect the polyester problem
>>(which we really can“t), we would still need a lot of rows to get a
>>useable amperage. Another problem might lie in the fact that they are
>>"S"MD. The distance between the layers and the end "plates" is
>>very small and the surface is "open" to grime and dust. This might
>>present a problem with corona and or voltage creepage along the
>>surface. If you pot it in something solid (like epoxy) you will never
>>be able to rebuild it. If you use an oil bath, then you have one of
>>the things I like to avoid around HV: oil ;o). And....... wouldn“t it
>>look kind of awkward having an 8" coil with a SMDMMC the size
>>of two cigarette packs? ;o)). It might be an interesting idea for
>>a µTC, tho. 2-4" sparks from a "cigarette pack and a 9V" {;./\)
>>Or how about feeding the output from this into an helium filled
>>bag floating above your head (sort of like a halo ;o)).
>>
>>Coiler greets from germany,
>>Reinhard
>>
>>
>
>We us American Technical Ceramics 3600 volt 470 pF caps at work.  These are
>very high Q caps that cost about $5 each.  Far too expensive for Tesla work
>but they do exist...  They are about 0.5 x 0.5 x 3/16 inch.
>
> Terry
>

Of course, I was too lazy to look at the ATC catalog next to my desk...
What are mere $$ in search of a truly fine piece of equipment, using the
latest in technology???

<<<< I looked them up and they were really 390pF at 3600 volts peak.  You
would need six in series to get the voltage to 21600 which means you would
need 163 strings or 978 caps to make a 10.6 nF cap.  That would work out to
$4890 bucks!!!  Although they could probably take a thousand RMS amps
(NPO)... - Terry >>>>