# Re: MMCs and cap calculations?

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

Hi Nathan,

At 08:16 PM 3/10/2001 -0800, you wrote:
>greetings list!
>
>
>It's been a while, but I'm getting all excited about coiling again, and have
>a new interest in cap discharge banks too (starting small of course!).
>Anyway,

Cool!

>
>I forgot how big my coil's cap was so I busted out the physics books and
>tried to figure it out myself.
>
>Mine is an MMC- 6 series strings, 10 caps apiece (Terry's digikey caps) in
>parallel.
>
>The caps say both 563 J and 1.6 KVDC on them, so using the equation Wc
>(Joules) = 1/2CV^2, I get ...440uF each?

The 563 is the value in pF.  The first two digites (56) are followed by 3
zeros to get 56000pF or 0.056uF.  The J is the tolerance which is 5%.  That
is the common way caps are marked.  So the first two digits are followed by
the number of zeros indicated in the third digit.

The value of the cap is 56nF x 6 / 10 = 33.6nF.

Cheers,

Terry

>
>I just found digikey and recalled that they were .056uF apiece, which makes
>a LOT more sense and fits what I remembered about my capacitor.
>
>What's up? Is it me, the caps or the physics book?
>
>Thanks,
>Nathan B
>
>_________________________________________________________________