Re: calculations of capacitance

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: Frank <fxrays@xxxxxxxxxx>

Hi,
Basic algebra, you have to have the denominators the same to add, you 
just cannot add top and bottoms.

OK, you have for the denominator;

6/1n + 1/10n = 60/10n + 1/10n = 61/10n. Inverting this for the final 
answer is 10n/61 = 0.16 n which is correct for your first answer.

You cannot just add top and bottoms in fractions, you have to make 
the bottoms all the same values first before adding and then the 
bottoms do not add, just the tops!

In your example too, the final voltage rating is 6 X 6KV + 1 X 2KV + 38 KV.

Frank

At 05:12 PM 2/19/2007 -0700, you wrote:
> Original poster: "James Howells" <james@xxxxxxxxxxxxxxxxxxxxxxx>
>
> I don't know why but I have got myself completely flummoxed trying 
> to work out a primary cap from the components I have at hand
>
> I don't have enough capacitors of the same value to do a normal MMC 
> and want to mix and match what I have got But I have got myself in a 
> real error loop
>
>
> Say I have 6 caps at   1nF and voltage rated at  6KV
> I put them in series then add( in series) a 10nF capacitor but only 2KV
> I know I don't get 32 Kv rating ..but what do I get ?
>
> I have worked out the total capacity  1/ total =   1/c1+ 1/c2+ 1/c3 
> .............
> and got two different answers
>
> 1/10+ 1/1 ..................1/1       = 1/    .1 + 
> 6      =  6.1    invert for total cap =    .16nF
>
>
> OR
>                    adding all the numerators and denominators  you 
> get    7/16   =  invert to give TOTAL =  2.28nF
>
> I really have confused my self
>
>
> Replies to
> James
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