Re: [TCML] how much does secondary diameter affect efficiency?

[Futuret <futuret@xxxxxxx>]

Yes, 26awg is probably good.  You probably want about 1300 turns
on the coil (1000 to 1500 turns)  You could make the coil winding 
25" long probably and still get enough coupling without setting the 
primary too close to the secondary (you don't want arc-over).   
You can check this all out in JavaTC to insure you have enough
coupling while still leaving at least an inch between the inner
turn of secondary and the primary coil.  Coupling should be about
k = 0.2 probably.  You can always raise the secondary if you get
flash-over or racing sparks.  Your main toroid should probably be
the size of Gary Lau's toroid or similar.  One of the reasons for
using a large coil for high power is to handle the coupling.  
A small coil run at high power will necessarily need looser
coupling as a design compromise.  The secondary winding
should be well coated with polyurethane or envirotex or whatever
coating you use, to prevent coil breakdown at high powers.  

John

 

 

 

-----Original Message-----
From: James Hutton <b-u-r-t-o-n-boy@xxxxxxxxxxx>
To: tesla help <tesla@xxxxxxxxxx>
Sent: Wed, Feb 29, 2012 4:11 pm
Subject: RE: [TCML] how much does secondary diameter affect efficiency?



does 26g sound good?

> To: tesla@xxxxxxxxxx
> Subject: Re: [TCML] how much does secondary diameter affect efficiency?
> From: futuret@xxxxxxx
> Date: Wed, 29 Feb 2012 16:04:45 -0500
> 
> James,
> 
> If you use the 4" form, you may want to use wire that's a little thinner
> than usual to keep the inductance high.  Also the form should be a little
> taller than a typical 4" form.  In other words make the form almost as tall as
> you would use for a 6" form.  You may probably want to use two toroids
> also; a larger one above a smaller one.  This will keep the sparks farther
> away from primary and ground.  By doing these things, you'll keep the
> efficiency reasonably high.  In truth, this is the way to build a coil that's
> compact, yet reasonably efficient.  The primary will tend to be smaller
> in diameter too which will make the coil more compact.  But the toroid
> must be large to get the full spark length capability.  
> 
> Your spark gap break rate will be a factor too.  Higher break rates are
> less efficient but have smaller bang sizes and should stress the secondary
> less.  
> 
> As you can see, there are many factors to consider overall. 
> 
> Cheers,
> John
> 
> 
> 
> > James,>       Coil diameter has little to do with efficiency, and too large 
of a> secondary will make your coil look unimpressive...  Go with the 4 inch,> 
and don't look back...  I use 4.5 inch for about 3 kW with no problems> at 
all...>> Scott Bogard.>> On 2/28/2012 4:48 PM, James Hutton wrote:>> Hello, I'm 
about to begin building a 15kv 120ma coil.I read somewhere>> that with powers 
over 1.5kw, you should be using atleast 6inch PVC.I>> have lot's of spare 4inch 
PVC, but I can't seem to find any 6inch at any>> local hardware stores. (except 
for 10ft long 6inch sewage pipes for>> $70)So I'm just wondering if it is 
absolutely necessary to go bigger>> than 4 inch when using 1.8kw, and how much 
it would affect the>> efficiency of the coil if I use 4 inch instead of 6.(also, 
If I do use 4>> inch, how long should my windings be?)>> thanks!>>>> -James 
Hutton 		 	   		  _______________________________________________>> Tesla 
mailing list>> Tesla@xxxxxxxxxx>> http://www.pupman.com/mailman/listinfo/tesla>>> 
_______________________________________________> Tesla mailing list> 
Tesla@xxxxxxxxxx> http://www.pupman.com/mailman/listinfo/tesla>>_______________________________________________Tesla 
mailing listTesla@xxxxxxxxxxxxxx://www.pupman.com/mailman/listinfo/tesla
>  
> 
> 
>  
> _______________________________________________
> Tesla mailing list
> Tesla@xxxxxxxxxx
> http://www.pupman.com/mailman/listinfo/tesla
 		 	   		  _______________________________________________
Tesla mailing list
Tesla@xxxxxxxxxx
http://www.pupman.com/mailman/listinfo/tesla

 
_______________________________________________
Tesla mailing list
Tesla@xxxxxxxxxx
http://www.pupman.com/mailman/listinfo/tesla