Re: MMC vs. homemade capacitors

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

Original poster: "by way of Terry Fritz <twftesla-at-uswest-dot-net>" <FutureT-at-aol-dot-com>

In a message dated 12/22/00 10:17:47 AM Eastern Standard Time, 
tesla-at-pupman-dot-com writes:

Paul, all,

It is well known that 0.060" poly works well for 7.5kV.  Or two caps
in series as you are using for 15kV.  The rolled caps designed by
Richard Hull of the TCBOR used this thickness and voltage rating.
These methods are shown on his videotapes.  I have four of the
rolled poly homemade caps that I've been using for years now.
I bought them from a local coiler.  Many coilers throughout the
world have built and used these caps successfully.  It is only when
one uses too much voltage on these caps, for instance 12kV or
15kV on a single 0.060" cap, that they fail.  Some folks may have
had some resonant charging or inductive kick charging occuring
in their TC also, which raised the voltages higher than they
realized.

Although it's a lot of work to build these caps, and they are very
bulky and messy, it pays off if one can obtain the parts at low cost.
You're trading work for $$$, when comparing these with MMC type
caps.

The MMC's are good because they are relatively low cost, easy
to build, reliable, reasonably compact, non-messy, can be repaired,
and can be arranged to obtain many different capacitance and voltage 
ratings.  Although I have not used them, I think they're great.

John Freau
--

> 
>  I have succesfully operated my coil now for three years. I power it with 
7.5 
> 
>  Kw. Thats 15 kV at 500 ma. My caps are simple. Everyone said they wouldn't 
>  work or if they did would not last. They are made from .060" thick poly 
>  single sheet. The plates are 8 x 12". The effective area is 77 sqin. It 
only 
> 
>  took me 3.5 Hrs to make it. There 48 plates, in each cap. I have made 4 of 
>  these. In the tank circuit There two in parallel and two parallel sets in 
>  series. Total capacitance .026 uF. You will only need 1/4 of this. The 
cores 
> 
>  were placed in tupperware containers and filled with oil. To release 
trapped 
> 
>  air I use a 2300 v Micro wave transformer and ran the caps for 35 or 40 
>  minutes. About an hour later I ran them at 7500 v. for an hour. After this 
I 
> 
>  placed them in service. No flash over no failures.(Three years of service) 
>  My guess is that they would survive even at 30 Kv. Very simple to make and 
>  almost indestructable.
>  
>  PS: I hope this helps.
>  
>  If you have any questions just contact me by e-mail.
>  
>  Paul M