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Richie's Homepage and other topics
Message text written by INTERNET:tesla-at-pupman-dot-com
Malcolm,
I certainly with your comments on Richies web page.
Thanks for the comments on my web page:
>(1) Mark Barton's 10kW flamethrower was definitely using IRF840
FETs.
This makes sense to me - Mark refered to irf540 in an email somewhere
but these are 100V max compared to 500v for the irf 840. Do you have any
other details of Marks "flamethrower"? (This was a 10kW Solid State
Coil that produced a 3 foot wall of flame before the smoke came out)
>(2) Duane Bylund's use of DC resistance as a starting point for
>matching a driver to a secondary could IMHO be bettered somewhat
>but there is still a rider. Firstly, a better match for the driver to a
non-
>sparking coil could be done by *accurately* measuring the Q of the
>coil and deriving its ESR using R = SQRT(L/C)/Q. This figure is
>considerably higher than the DC resistance of the coil in general
>and should be good for direct coupling. For k < 1 this figure would
>be higher.
>The rider: this figure would also be better for sparking conditions
>(corona in particular) as the impedance at the base of the
>secondary rises while the load impedance at the top reduces ( I
>have measured this and infer that 1/4 wave transformer principles
>do apply to the secondary - the base impedance swings about Zo^2
>in accordance with loading). This is my opinion anyway. I
>measured this using link coupling to the base of a resonator a few
>years ago. Comments, measured refutations welcomed.
That still leaves the problem of measuring the Q. I really now resort to
making multitap output transformers. Good old suck it and see!
My page in at
http://ourworld-dot-compuserve-dot-com/homepages/alansharp/
Alan Sharp (UK)