Re: Geek Caps - Ratings and longevity

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Terry Fritz" <teslalist-at-qwest-dot-net>

Hi Chris,

At 05:43 PM 7/2/2003 -0700, you wrote:
>Hi guys,
>It's been about 5 months since I have gotten my 6 inch coil working, and 
>up until now it has been running perfectly. About a week ago though, the 
>coil started acting strange. It only makes sparks about half as big as 
>they should be and it makes a strange hissing noise while running. I 
>checked the NST and it still works perfectly. I also looked at the spark 
>gap but nothing seemed out of the ordinary there either. I double checked 
>the connections everywhere and they were fine also. So I now have to be 
>suspicious of my MMC again. This time at least, they didn't blow up 
>immediately so I know I'm doing at least someting right. =D
>The MMC is 2 strings of 6 geek caps, giving it a value of .5ufd and a 
>12000 volt rating. My transformer is a 9kV 120ma NST, so it should be fine 
>with the RMS voltage. However, the peak voltage on the transformer is 
>somewhere around 12500 right?

9000 x SQRT(2) = 12728 Volts.

>I know that these caps are made to tolerate quite above their ratings, but 
>over time could they eventually break down from repeatedly running them 
>above their ratings?

Unlikely in very limited use.  Geek caps snap at about 3500 volts each.


>  The outer tape covering the caps are now severly wrinkled and covered 
> with dents, which may be where they were blasted through.

If they are "new" dents and wrinkles, that would be "bad".  CD caps 
normally are a little rugged on the outer surface and they may settle with 
time.  However, if they are obviously "falling apart" during use, something 
is wrong.

>Either that, or something else is wrong and the tape may just be wrinkled. 
>Terry, would you mind doing another MMC inspection to see if these things 
>still work?

I can certainly check them here if you want to send them to me.  As far as 
I know they should work fine, but if you think they are the 6x2 string 
things needs a check we can certainly do it.  A nice high resolution 
picture close up of a "bad" cap sent to me may work just as well too.

Cheers,

         Terry
         terrellf-at-qwest-dot-net



>-Chris