Re: The ultimate MMC cap

• To: tesla-at-pupman-dot-com
• Subject: Re: The ultimate MMC cap
• From: Mark Finnis <mefinnis-at-medicine.adelaide.edu.au> (by way of Terry Fritz <twftesla-at-uswest-dot-net>)
• Date: Mon, 13 Dec 1999 05:34:22 -0700
• Approved: twftesla-at-uswest-dot-net
• Delivered-To: fixup-tesla-at-pupman-dot-com-at-fixme

At 01:31  11/12/1999 -0700, Nick field wrote:

>Hi All,
>          just to offer some help to those of you in a quandry (ahhh the
>english language) over which caps to use for your mmc.  After looking at the
>wima, philips and RS capacitors I've found the ones that I think are the best
>value for the performance.
>These are the philips 376 high pulse series.  These have a dv/dt of
>10000V/µs, which makes them the highest pulse rated caps available for the
>price. The voltage rating is also the best for the price.  The 0.047µF 2kV
>units cost £0.333 (55c) each in 100+ quantities. Unlike the wima units the ac
>rating does not seem to be disproportionate to the DC rating as the ratings
>increase - the 2kV units are rated at 650VAC.
>I'm using 300 of these in my big coil and actually running them at the
>datasheet ac rating.  Just thought I'd alert you guys to this capacitor as I
>haven't seen anyone else using them.

Certainly looked at them, but down in Oz they are > $2.50 from Farnell.

Anyhow, finished 4/5 of my MMC and hooked it up to my large coil for a 
preliminary firing on Saturday night.

Finally used the Wima FKP-1 0.047uF/1.6kV caps.

         Strings -at- 15  =  24 kVDC
         Parallel -at- 24  =  0.068 uF (measured)

Have the caps for another 6 strings, which I will add in due course (this 
is one nice attributes of MMCs, you can just keep extending them).

Coil is way off tune/optimum but got some nice 5-6' streamers.

The MMC never had even a perceptible temp. rise using break rates to 400bps.

OK, OK, so I'm converted ;-)

Now for some serious optimization work !!

Cheers

MArk

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