Re: Small v.s. large primary

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

Original poster: Dave Leddon <leddon1-at-llnl.gov> 

Ed,

I ended up with a primary configuration, much like yours, not because 
Richard Quick recommend it, but as the result of evolution.  I started with 
18-inch diameter primary comprised of 2-inch wide copper ribbon spaced at 
1/4 inches between turns tapped at about turn 5 coupled with a 120 nF cap 
and a 12-inch diameter secondary.  The coupling factor was only 0.12 with 
the starting winding of the secondary 3 inches above the plane of the 
primary.  This configuration would consistently weld adjacent turns in the 
first couple of inches on the secondary whenever I cranked the input power 
much above 5 kva.  Dr. Resonance pointed out that he had a similar problem 
on one of his early coils which also used ribbon and suggested that the 
edges of the ribbon were causing intense energy gradients and that I should 
change over to copper tubing.  So I re-wound the primary, keeping 
everything else the same, and ended up with a primary diameter of about 20 
inches, still tapped at about turn 5.  I still had the same problem, 
however at about 5 kva input.

So I rebuilt the primary with 1/2-inch copper tubing having about 11 turns 
with a 30-inch diameter tapped at ten turns and  I dropped the size of the 
tank cap down to 92 nF.  Voila, no more welded turns, even when running the 
coil full-out at 280 volts -at- 50 amps and the output of the coil seems 
respectable at 14 feet (measured using a segmented gap).  All of this was 
done with a 300 bps break rate and I note that when I drop down below 240 
bps, the arc intensity is significantly greater, so there probably is 
something to be said for larger bang size at lower break rates.

Dave

At 05:27 PM 12/9/2003, you wrote:
>Original poster: Esondrmn-at-aol-dot-com
>In a message dated 12/9/03 7:46:49 AM Pacific Standard Time, 
>tesla-at-pupman-dot-com writes:
>
>- much snipping here -
>
>>So who's right?
>>
>>My personal experience with a 12" diameter pig fed coil supports Richard's
>>observations but I see pictures of a lot of large coils using primaries like
>>those described by Dr. Resonance.  So, what's the consensus among those 
>>of you
>>who have built pig-powered coils?
>>
>>Dave
>
>
>Dave,
>
>I do get 108" sparks out of my 6" coil running at 5 kva to 7 kva.  That 
>primary is tapped at about 10 turns.  I don't think that has been beat to 
>my knowledge.  A very good discussion.
>
>Ed Sonderman


***************************************************************************
David H. Leddon
Lawrence Livermore National Lab