Re: Secondary size - the Why

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

Original poster: Mddeming-at-aol-dot-com 

Hi All,

     I have spent the last two days trying to figure out an answer to 
Luke's question of why ratios of 4:1 or 5:1 are good for secondaries. I 
think I have found a partial answer. In a TC, it is desirable to make Cp/Cs 
as large as practicable to maximize Vout. More of the energy gets into the 
streamers if the distribution of Cs between C self and C top is weighted 
towards C top.
     The problem thus becomes: "For a given length and diameter of wire, is 
there a particular diameter and length that minimizes C self?" After 
running a number of coils with 1667 ft, 2000 ft, and 6000 ft. of #24 wire 
through an Etesla6 analysis, it turns out that in each case I tried with 
secondaries from 2in. to 20 in.diameters, the Cself min. point occured when 
the H/D ratio was between 4:1 and 5:1. It would take considerable time to 
run a large number of different gauges, lengths, and pitches through the 
program and the result would still be empirical rather than theoretical and 
by no meas exhaustive. But at least it points the way to some rationale for 
using these ratios as a starting point.
Matt D.

Matt D.