Re: Coil diameter choice criteria

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

Original poster: "Jim Lux by way of Terry Fritz <teslalist-at-qwest-dot-net>" <jimlux-at-earthlink-dot-net>

At some point, the spark length starts to become a very large multiple of 
the coil height, and primary strikes, etc. start to be become a 
problem.  Also, the winding dimensions may be 5:1, but the secondary form 
might be a bit longer..

If I had to formulate a guideline, perhaps the secondary should be no less 
than 1/3 the expected spark length, which in turn would be 
1.7*sqrt(watts)..  Mind you, particularly at higher powers where rotary 
gaps are more common, break rates enter into the equation..

So, here's my wag, without actually looking over what folks currently use...

Watts   Spark   Sec Height      Sec Diam
500     38"     12-18"          2-4"
1000    54"     20-30"          4-6"
1500    66"     24-36"          5-7"
2000    76"     30-40"          6-8"
5000    120"    40-60"          8-12"
10kW    170"    60-80"          12-16"

One could probably also scale the size of wire for the secondary, by using 
an assumption that somewhere around 750-1200 turns are wanted, so, for 
instance, at the 2kW level, where your secondary is say, 36" long, you'd 
have about 25-30 turns per inch, which corresponds to, say, AWG 18-20

At 08:11 AM 7/23/2003 -0600, you wrote:
>Original poster: "Gerry Reynolds by way of Terry Fritz 
><teslalist-at-qwest-dot-net>" <gerryreynolds-at-earthlink-dot-net>
>
>I was wondering if there is a standard criteria for deciding when one 
>needs to go to the next size larger coil diameter.  Assuming coils are at 
>a 5:1 aspect ratio, is there a maxium something (voltage, or power, etc) 
>for this decision?
>
>Gerry R
>Ft Collins, CO