Re: How do I work out secondary former diameter?

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

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

In a message dated 12/7/00 3:48:26 PM Pacific Standard Time, tesla-at-pupman-dot-com 
writes:

<< 
 Are there any rules of thumb for decicing the secondary former diameter? 
 What are the advantages/disadvantages? 
 
 I will be using a 15/60 NST, 1600 turn secondary, not sure what size 
 toriod yet. 
 
 TIA 
 Seth Fischer 
 
  >>
Seth,

It kinda depends on how much money you ultimately want to spend on this 
project and how long of sparks you will be happy with.  I built a 6.0" 
diameter coil, running about the power level you have in mind.  It performed 
very well.  I kept adding more and more power, trying to see how long of 
sparks this coil could really produce.  From the first configuration, I ended 
up spend several hundreds of dollars to get larger (commercial) caps, larger 
variacs, 5 kva distribution transformer, control ballast for it, rotary spark 
gap, larger toroids, etc. - there is no end to this.  Now, I wish I had an 
8.0" or 10.0" diameter secondary.

I have since built a 3.0" diameter coil so I can have a smaller inexpensive 
coil system to do testing with.

My suggestion:  go with a 6.0" diameter secondary with a flat primary made 
from 3/8" copper tubing, about 14 turns.  This coil will perform well with 
just neon sign transformers and a static spark gap - and will provide a basis 
to grow the project if you get the serious bug.

Ed Sonderman