Re: salt water capacitors

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

Original poster: "Gregory Hunter by way of Terry Fritz <twftesla-at-qwest-dot-net>" <ghunter31014-at-yahoo-dot-com>

Hi Nick,

After a hasty study of your coil specs I think the
problem is your cap. It's too small. 12 beer bottles
is good for about 10nF. To tune with 10nF, you'd need
about 30 turns on your primary. To tune with 12 turns,
you need about 80nF. That's a lot of beer bottles! I
did it though. I used 98 Miller Genuine Draft bottles
to build an 81nF cap for my 5kva pole pig coil. I even
figured out a convenient way to wire all those bottles
in parallel. Have a look at my web site some time to
see the big saltwater cap. Now if 100 lbs of beer
bottles & brine is not your bag, then you should
really investigate the MMC. 80nF at 12kvdc is a snap
using MMC fabrication techniques. In case you're
wondering, the level-shifted twin MOT supply is a
brute, quite capable of fully exploiting an 80nF cap.

Another possibility is to build a two-layer primary in
order to achieve enough inductance to tune with 10nF.
That would require a fairly major rebuild, but of
course, that's your call. I've never built a two-layer
primary, so I'll take a pass on offering any more
advice about it.

Best Regards,

Greg
http://hot-streamer-dot-com/greg

--- Tesla list <tesla-at-pupman-dot-com> wrote:
> Original poster: "Nick Graber by way of Terry Fritz
> <twftesla-at-qwest-dot-net>" <nickgraber-at-home-dot-com>
> 
> hello all I am having some troubles with my tesla
> coil and cant seem to figure
> out how to correct it I belive i dont have the
> correct capacitance.  first of
> all my coil stats
>  
> -primary tank
> 2 mot's with voltage multiplyers that brings it up
> to 12kv or so
>  
> -sparkgap
> easy multi gap spark gap made of copper pipe and a
> pice of plexy glass
>  
> -capacitor 
> this is the unknow. I made a saltwater bucket that I
> read about on geek group
> that is 12 carona bottles in a 5 gallon bucked with
> all of the bottles filled
> up to the bend were the neck of the bottle starts I
> cant seem to figure out if
> I have toomuch capacitance or too little.
> -primary
>  12 3/4 turns of 1/4" copper tube spaced at 1/4 with
> a 8" diamiter whole for
> the secondary.
>  
> -secondary 
> 4.5" diamiter pvc wound with 32awg wire 30"
> tall(windings are 29" of the 30)
>  
> so if someone can help me to get my capacitance
> problem fixed I would be
> greatfull I can get about a 5" arc off of it as of
> now.
>  
> Nick Graber
> nickgraber-at-home-dot-com
> 
> 
> 


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