Re: what is the best wire size to use?

["Tesla list" <tesla@pupman.com>]

Original poster: "by way of Terry Fritz <twftesla@uswest.net>" <FutureT@aol.com>

In a message dated 12/29/00 2:15:54 PM Eastern Standard Time, 
tesla@pupman.com writes:

> Hi Chris,
>  Generally, the lower to medium powered NST driven coils work
>  best with a smaller guage wired secondary because you can 
>  get a higher # of turns per inch (or cm) which increases the na-
>  tural inductance and allows for a larger primary cap and higher
>  primary inductance. This in turn lowers the gap losses. John
>  Freau has pioneered research in this area. This also dictates a
>  higher aspect ratio (height/dia. ratio). I think John's TT-42 12/30
>  NST driven coil, whigh produces 42" or ~ 1 meter sparks, uses
>  about 1600 turns of #28 close-wound for the sec. on a 4" dia. 
>  (10 cm) form. I think his sec coil ends up around 23" or so in 
>  length, which gives about a 6:1 aspect ratio. 

David, Chris,

Those figures are correct for my TT-42 coil.  However I get better
results using a 6.5" dia x 24" form still wound with #28 wire.  
Using the 4" dia form, I needed to use a robust 12/30 NST to get
the 42" sparks.  But using the wider form, I can use a run-of-the-
mill 12/30 NST to get the 42" sparks.  The TT-42 coil was designed
to be compact and portable, with some sacrifice in efficiency.

I advocate 1600 turns of wire, but not necessarily a high aspect
ratio unless you want a compact coil.  A wider form is still the
best, because of even higher inductance, and the still lower gap
losses that result.

John Freau