Re: what is the best wire size to use?

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

Original poster: "by way of Terry Fritz <twftesla-at-uswest-dot-net>" <Tesla729-at-cs-dot-com>

In a message dated 12/28/00 3:27:07 PM Pacific Standard Time, 
tesla-at-pupman-dot-com writes:

Chris Telford wrote:
<< would i be better off winding a more numerously turned
 primary and using 28swg wire when using these
 dimmensions of secondary coil, or is the performance
 increase of the 28swg wire coil over the 24swg coil
 explained by the difference of wound length? I was
 under the impression that the long thin design of
 secondary coil was ineffecient, and that squatter
 shaped ones performed better. 
  >>

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. 

The shorter, fatter secondaries (lower aspect ratios) with larger
guage wire are the better choice for high powered, pole pig driv-
en systems. With a larger dia. secondary, one can get by with
a fewer # of turns and still have a relatively high inductance. My
10 kVA poe pig Tesla coil system uses a 12" dia. concrete form
cardboard tube for the sec form and is wound with only ~660 turns
of # 16 magnet wire. The length is only about 38.5" (just under a
meter) but the output sparks are over 10 ft (3 meters)! The aspect
ratio for this one is only about 3:1. Hope this helps you out.

Keeping 'em Sparkin' in Memphis,
David Rieben