Re: Pulsed Tube Coil Work (with updates)

To: tesla-at-pupman-dot-com
Subject: Re: Pulsed Tube Coil Work (with updates)
From: FutureT-at-aol-dot-com (by way of Terry Fritz <twf-at-verinet-dot-com>)
Date: Fri, 12 Mar 1999 12:26:54 -0700
Approved: twf-at-verinet-dot-com

In a message dated 99-03-10 16:41:32 EST, you write:

<< Original Poster: Alan Sharp <AlanSharp-at-compuserve-dot-com> 
 
> John,
 
> My  interest is in pulsed mosfet driven magnifiers, rather than
> tubes, but I suspect that secondary doesn't care whether it's
> being driven by a mosfet or a valve.
 
> Naturally I want to produce long sparks. I have in the past managed
 12" at 150 - 800watts but I think I could do better.
 
 >Could you describe what your best performing primary / topload /
>secondary arrangement and make a guess at the input impedence of
> the secondary. If its not too far from the 100kHz to 250KHz that I can
 >work with I'ld like to reproduce it and drive it with my new mosfet bridge,
 >either via a primary coil, or more likely build a matching transformer
> and bottom feed it. 
 
> Alan Sharp (UK)
  >>

Alan,

I don't think it's all that critical at least in the tube coils I build.
There
seems to be a wide range of acceptable secondary sizes, wire
thicknesses, frequencies, etc.  I basically use two sizes of secondaries
for the tube coils.  ONe is 3" by 11.5" wound with #28awg, with a 1.5"
by 6" toroid, with point on top of it.  Resonant freq. is about 500kHz,
The other is a 6" by 23" secondary
also wound with #28 wire.  Resonant freq is about $110 kHz.
But I know that others have used radically
different wire sizes, such as #20awg, and gotten the same results.
I have no idea what the input impedances are.  But the specs for
some of these coils are at David Trimmel's website (he mentioned
the address yesterday or so). 

I've tried a toroid on the larger secondary and it worked the same,
but the toroid did help the smaller secondary and increased the
spark by 1".  I didn't do any comparisons with other secondary 
sizes.

John Freau