# Re: Cap values for 12/120(s)

• To: tesla-at-pupman-dot-com
• Subject: Re: Cap values for 12/120(s)
• From: Terry Fritz <twftesla-at-uswest-dot-net>
• Date: Thu, 24 Jun 1999 17:07:28 -0600
• Approved: twftesla-at-uswest-dot-net
• Delivered-To: fixup-tesla-at-pupman-dot-com-at-fixme

```Hi CHURCHMON,

Typically, you just use the old V/I=R formula to find the source impedance
of the transformers.  Then you use R=1/(2 x pi x 60 x C) to match the
capacitor to that source impedance.

So, for say three 12000 volt 120mA transformers:

12000 / (3 x 0.120) = 33333 ohms

1/ (R x 2 x 60 x pi) = C

1/ (33333 x 2 x60 x pi) = 79.5nF

If you have 50 Hz AC line frequency replace the 60s with 50s....

Your friend is probably pretty close.

Cheers,

Terry

At 02:51 PM 6/24/99 -0400, you wrote:
>Hi all , Here's the situation I have a few 12/120(s) and need to figure out
>what size cap(s)  I need to reach resonance ? When trying to figure this out
>my friend Dave said it could need as much as a.06!  This seems like a bit
>much to me , however when we paralleled two together  on our 8" coil with my
>.027 plate cap it worked very well.
>These are 40year old Solas (very robust) 800va transformers.With the primary
>open resistance end to end is1950 ohms and inductance measured on one side is
>85h and 80h on the other with 116h end to end.
>If anyone can help figure this out  it would  be greatly appreciated.We plan
>on running one or more so I need to know  idividual  cap size as well as for
>running 2,3,or4 trannys he hehe!
>All in prparation for the So Cal  Teslathon  Thanks again Mike Church
>(CHURCHMON) -at-AOL
>

```