Re: Pulsed Tube Coil Work (with updates)
In a message dated 99-03-10 16:41:32 EST, you write:
<< Original Poster: Alan Sharp <AlanSharp-at-compuserve-dot-com>
> 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)
I don't think it's all that critical at least in the tube coils I build.
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