rolled caps

To: "'Tesla List'" <tesla-at-pupman-dot-com>
Subject: rolled caps
From: Tesla List <tesla-at-stic-dot-net>
Date: Tue, 21 Apr 1998 00:31:06 -0500
Approved: tesla-at-stic-dot-net

----------
From:  Alfred A. Skrocki [SMTP:alfred.skrocki-at-cybernetworking-dot-com]
Sent:  Monday, April 20, 1998 6:39 AM
To:  Tesla List
Subject:  Re: rolled caps

On Sunday, April 19, 1998 11:43 AM Kevin Wahila
[SMTP:kevinw-at-stny.lrun-dot-com] wrote;

> a while ago i began planning and construction of my first rolled caps.
> since then my coiling was put on hold for some time.  now, as i go back and
> look through my mail and information to refresh my memory, i have found a
> slight problem dealing with the equation to calculate capacitance for a
> rolled cap.  i have two different mails from the list with two different
> answers
> 
> #1......
> 
>             0.224 x K x A
>        C  = ------------- x (N - 1)
>                   D
> 
> C = Capacitance (in microfarads)

This is in error it should read C = Capacitance ( in micromicro farads or 
pico farads)

> K = Dielectric constant
> D = Distance between plates in inches
> A = Area of plate in inches
> N = Number of plates
> 
> and....
> 
> #2.....
> 
>                           2.248965 * 10^-7 * K * A
> C (microfarads) = ------------------------------------ * (N-1)
> K=dielectric 
> const.
>                                          d
> 
> !!!Again, you need to multiply this result by 2 for a rolled up cap.
> This is the formula I generally use when making homemade caps.
> 
> ok, so which one is the right one?

After the above correction on the first equation they are the same.
I found this same error in the archives in one of Richard Quicks files and 
Chip was nice enough to correct it for the benifit of all.

                                       Sincerely

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