Re: [TCML] Intro and questions

[FutureT@xxxxxxx]

In a message dated 12/7/2007 2:54:52 P.M. US Eastern Standard Time,  
dunnsept@xxxxxxxxxxx writes:

>I have a franceformer 9kv 30mA nst I will use for my first coil.  I've read 
online about the range of sizes >appropriate for use
>given  a particular input. What are the parameters for the choice though? 
How do I  decide if I should use >say 2 inch versus 3
>or 3.5? 
 
Paul,
 
Welcome to the list.  The choice is mostly based on practical and  electrical 
considerations.
For example if the spark output is expected to be 24", then the  secondary 
should be
tall enough so the sparks will not arc back down to the primary or race  down 
the secondary.
A 3.2" x 16.5" secondary wound with 28 awg wire would work well for  example. 
 A smaller
secondary would work but may reduce the overall spark length.  A  somewhat 
larger
coil seems to give better output, probably because of lower wire  losses and 
a lower
frequency of operation.  For some reason 2" secondaries never seem  to give 
very
powerful sparks.  Again this could be because of the higher  frequency and 
higher
losses.  I tend to avoid that size except for very small  coils.
 
Coil design still has a large empirical aspect to it, based on experience  and
practical considerations.  
 
One approach would be to build the coil using a 4" x 19" secondary  similar 
to my
TT-42 coil.  This would permit you to upgrade to a larger 12/30 or  15/30 NST 
at
some point, and get the full benefit.  My TT-42 coil uses a 4" x 13"  toroid, 
but
for the smaller NST you'd probably want to use a 3" x 10" toroid or maybe  
something
smaller.  
 
The spark gap is the heart of a Tesla coil in many ways.  It's  important to 
use good
design and construction to get optimal results.  Capacitor sizing  (cap 
value) is also
very important for optimal results.  
 
>I don't have any of them available at home, I only would have 1"  PVC so I 
have to purchase PVC or >what-have-you
>regardless. I also  do not have  anywhere near enough wire so I will wind up 
purchasing that  too. The >wire choice, as I understand
>it should be such that for  whatever size form I have, I should get 800 - 
1600 turns with a winding/length  >ratio of about 5:1 (correct?)

>thanks for your input/feedback to  help this newbie get started  ;-)
>(for what it's worth, even  though I'm not particularly well versed in some 
of these aspects, I'd rather  >learn what I can about it rather than have 
someone just give me a shopping  list)


I assume you're familiar with Bart's JavaTC which is most useful  for 
calculating the various
coil parameters for tuning, etc.  My website is at:
 
   _http://hometown.aol.com/futuret/page3.html_ 
(http://hometown.aol.com/futuret/page3.html) 
 
I show my TT-42 coil, examples of rotary spark gaps, phase shift  circuit for 
sync
rotaries, theories, toroids, tube coils, staccato pulse work,  etc.
 
John


>tia
>Paul...








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