# Re: Where do I get a couple Caps

```Original poster: Terry Fritz <teslalist-at-twfpowerelectronics-dot-com>

Hi,

Sort of.  With a 4000V NST you want 6000 volts across the caps.  In the
Tesla coil case, we can use the DC ratings.  So four 942C20P1K in series
will give 8000 volts at 0.025uF.  When you put the caps in series, the
voltages add up and the capacitance value divides by the number of
caps.  It is nice to get the 0.15 or 0.10 caps from the geek group since
they sell in small quantity.  Jim also had a suggesting using caps from
DigiKey.  I am not sure how familiar your are with all this so let us know
if it is not clear.  We never know if noobs are plumbers or Ph.Ds in
electrical engineering till we get to know you ;-))

Are you sure 0.025uF is the value you need?  I would think you would want
an "LTR" size.  What kind (static or sync) spark gap do you want to use
(probably static)?

4000 / 0.03 = 133333 ohms = 1 / (2 x pi x f x C)

If f = 60Hz...  Then C = 19.56nF

LTR (static gap) = 19.56 x pi / 2 = 0.0307uF...

I would think that you would want 0.0307uF if you are using a static gap
and your line frequency is 60Hz?  Of course, I may have messed up the math
'as usual' too ;o))

Cheers,

Terry

At 01:35 PM 4/22/2004, you wrote:
>So is this the kind i want?
>
>http://www.cornell-dubilier-dot-com/film/9422000.htm
>
>(Part #:942C20S22K (3 one down))
>
>Nano2e
>
>
>---- Original message ----
> >Date: Thu, 22 Apr 2004 12:08:26 -0600
> >From: "Tesla list" <tesla-at-pupman-dot-com>
> >Subject: Re: Where do I get a couple Caps
> >To: tesla-at-pupman-dot-com
> >
> >Original poster: Terry Fritz
><teslalist-at-twfpowerelectronics-dot-com>
> >
> >Hi,
> >
> >Look here:
> >
> >http://www.thegeekgroup-dot-org/mmc/
> >
> >You could use six of the 0.15uF or four of the 0.10 uF.
> >
> >Cheers,
> >
> >         Terry
> >
> >
> >At 10:04 AM 4/22/2004, you wrote:
> >>Hey..I am looking for a total .024 uF in my MMC (did I say
> >>that right (NOOB!)) What should the rated voltage be if I
>am
> >>using a 4000V 30mA NST? What kind should they be (I am
> >>looking at Metallized Polypropylene)? And where can I get
> >>just a few?
> >>
> >>Nano2e
> >
> >

```