Re: There is no 'best ' wire size, all things are equal.

["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 1/18/01 2:19:29 PM Eastern Standard Time, tesla-at-pupman-dot-com 
writes:

> The primary was 2 turns of 3/8" copper tubing and the supply
>  was two 15/60 unpotted neons with 2 shunts removed from each side.
>  Capacitors in the tank were double ganged 4700pf in series x 15 in
>  parallel barium titanate "doorknobs" rated at 40kvdc. A total of 30 of
>  the 'doorknobs'.  Anyway, this was meant to be the drive for a maggie but
>  it gives great sparks and arcs over 48" driven as a plain secondary. 
>  What surprised me most was that we only needed 2 turns of primary to get
>  this thing to give out with these big arcs.  You know what Harvey?  I
>  would appreciate it if you could give me some idea of the parameters of
>  this coil if you figure it out since it sounds like you have an
>  understanding of math which is much better than mine.  And perhaps other
>  mathematically inclined list members could shed some light on why this
>  works so well for us. Thanks,  AL.

Al,

An efficient TC will give sparks according to the formula:

    spark length (inches) = 1.8*sqrt input watts (wallplug)

If we assume that a 15/60 NST will draw it's rated current
(it actually can draw much more), that would be 900 VA for
each NST.  For two NST's that's 1800 watts.  Using the formula
gives 76" for the spark length, compared with the 48" you're
obtaining.  Now since you've removed some shunts, the sparks
should be even longer.  Also, since NST's can draw more than
their rated current, even without removing any shunts, this
means the sparks should be even longer.  

Consider for example Gary Lau's nice TC which gives 61" sparks
using a single unmodified 15/60 NST.

So my conclusion is that your coil which gives 48" sparks using
two modified 15/60 NST's is rather inefficient.  I don't mean to
criticize your coil in any way, I'm just giving an analysis since
you asked.  I'm surprised the sparks are not even longer using 
the two turn secondary.  Although two turn secondaries are not 
so great, they're not necessarily terrible either.  Those doorknob
caps may be somewhat lossy, so that may be hurting the 
spark length some.

John Freau