Re: Capacitor

On Thu, 11 Jul 1996, Tesla List wrote:

> From paulmil-at-ibm-dot-netThu Jul 11 22:06:59 1996
> Date: Thu, 11 Jul 1996 13:50:57 GMT
> From: PAUL MILLOTT <paulmil-at-ibm-dot-net>
> To: tesla-at-pupman-dot-com
> Subject: Re: Capacitor 
> Scott,
> Re Bubble in Cap.
> Thanks for the reply. One reply is use it standing end on, the other is use
> it on its side.
> Any offers at 45 degrees?
> Perhaps a third reply will help me decide one way or the other. Any other
> comments.

If this cap is from info unlimited, chuck it away or use it as a bypass cap.
The cap has probably got mylar as a dielectric. I have used mylar caps 
with success, but runtimes over 45 seconds WILL destroy the cap. My mylar 
caps were homemade (I didn't know about polyethylene then) now that I use 
poly, I was interested to see how tough these mylar caps were. I had a 
friend charge them to 65kv DC with success. I put them in a tank circuit 
and ran them for 30 seconds flat. Even with over 2 litres of oil 
circulating around it still got VERY hot. After another 25 second fire, 
the caps failed. The cap you have may not be mylar, but if it is, don't 
use it in a tank circuit and expect long runtimes.

> Of course I explode my Tesla coils at my own risk, but as I pull the
> shrapnell from the walls it is nice to know that I got to this stage with a
> little help from my freinds and didn't just go ahead and do something stupid
> by myself.
> This extra worry about the cap is because 2 coilers with more experience
> than me have had recent explosions. I ain't going to be number 3.

This is the good thing about homemade caps. You can leave pressure vents.

> The cap is from Info unlimited and is for a 14" high coil I just built. I am
> still trying to get a coil to fire in this atmosphere.

I have thos btc3 plans too. The primary is a bad design in my opinion. 
Try making a bigger primary. (I beleive the btc3 one will not let you 
tune under 5 turns.)

> If anyone would like to sell me a small tuned in coil which they have tested
> and made notes about and that can be shipped fully built I would like to
> just plug it in here, untouched and see the differences due only to the
> atmospheric changes. Mains voltage here is U.K. standard 240 volts. I bought
> the BTC3 from info Unlimited, built and tested, and got max 4" arcs after
> retuning it here. Nothing came out at its preset tuning when it arrived. I
> can only assume the tuning changes in the different atmosphere unless Info
> Unlimited are not too good at Tesla Coils. It did look reasonably built though.
I don't think atmospheric conditions can effect a coil by this much.  
Mabe you put 240 volts through a 110-115 volt transformer and blew the 
cap. ( I am assuming you have the exact btc3 described in the plans.) Try 
grounding your coil a bit better. Try anything! :-)