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Re: scopes away - mosfet circuits
Richard wrote:
> I have always maintained that a
>doubling of input power by the most advanced coil expert (beyond 10KW) will
only yield >25% more
>spark. I further believe that even this ratio drops rapidly above 40KW!
I had anticipated an inverse square law to power / spark length, the extra
energy
has to make extra voltage and extra current. Inverse cube is bad news :-( but
there's no
arguement with experience and a reasonable mechanism - ionised air.
I do have another trick though, I control the power by switching at 60HZ
with a varying pulse lenght. I hope to pack more energy into each pulse
and reduce the pulse length (to keep the smoke under control).
See where it goes.
Richard - was very interested to see that your X10 magnifier was
such a small coil. I had assumed that I needed larger diameters
and heavier wires and that was the direction to go. I must try out
one of these little coils as a FET magnifier - though maybe with
a slightly smaller toroid :)
Brent wrote:
>From what you describe, sounds like you are running a half-bridge.
>Any chance of getting schematics and construction details???
Barry wrote:
>I am also attempting to build a mosfet driver system. Any help i.e.
>experience or schematics would be greatly appreciated.
My circuit is very similar to Rob's circuit - same PWM chip.
But I use a pushpull configuration instead of a half bridge.
If I was starting from scratch now I'd use Rob's circuit.
My present design has got a couple of quirks that I
hope to get straightened out on the Mark II - weird
feedbacks in the current limiting loop which I work
around.
Rob's circuit is posted in Web land -
ftp://nic.funet.fi/pub/sci/electrical/tesla/pictures/misc
you want driver.gif and driver.doc
check out the other pics while you are there.
Rob's coil didn't have a toroid - I'm sure that a modest
toroid would up the spark length by at least 50%.
Have fun
Alan Sharp.