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

[James Hutton <b-u-r-t-o-n-boy@xxxxxxxxxxx>]

alright i'll go with the 4inch and see how things go. I'm hoping for atleast 5.5ft streamers. I'll post pictures and results! thanks guys

> To: tesla@xxxxxxxxxx
> Subject: Re: [TCML] how much does secondary diameter affect efficiency?
> From: futuret@xxxxxxx
> Date: Wed, 29 Feb 2012 16:27:08 -0500
> 
> 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 
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