Re: Driving circuit FET problem

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Ben McMillen by way of Terry Fritz <twftesla-at-qwest-dot-net>" <spoonman534-at-yahoo-dot-com>

Hi Dan, All,
    Sorry about that.. I had forgotten about the high
frequencies.. I've been doing power systems stuff for a few
weeks now and I'm stuck in 60Hz mode.. ;)

Coiling In Pittsburgh
Ben McMillen

--- Tesla list <tesla-at-pupman-dot-com> wrote:
 > Original poster: "by way of Terry Fritz
 > <twftesla-at-qwest-dot-net>" <dhmccauley-at-spacecatlighting-dot-com>
 >
 >  > Hi George,
 >  >     When dealing with transformers of any kind, it is
 >  > important to remember one simple equation: power in =
 > power
 >  > out. It takes a certian amount of voltage and current
 > to
 >  > drive the primary side of a tranny. The voltages and
 >  > currents on the secondary are inversly proportional to
 > that
 >  > of the primary (depending on whether it's a setp up or
 > step
 >  > down) and power in must equal power out. When you
 > short the
 >  > secondary, the voltage drops to zero and the currnet
 > goes
 >  > way up. The primary is probably trying to compensate
 > and is
 >  > pulling too much current from the drive circuitry,
 > shutting
 >  > it down...
 >
 > Well not true.  Power in almost never equals power out.
 > And these losses
 > aren't small enough
 > to just neglect either especially when dealing with
 > larger and larger
 > transformers.
 >
 > At high frequencies, you can experience quite a bit of
 > losses to the core.
 > My 200kHz high voltage transformer requires
 > cooling for proper operation.  I could only wish power in
 > = power out ! ! !
 >
 > If you want some more information on SSTC's, check out my
 > website:
 >
 > http://www.spacecatlighting-dot-com/teslacoil.htm
 >
 > I've already built two solid state tesla coils and am
 > working on a Solid
 > State magnifier type coil this winter.  I'm also putting
 > together a page
 > which will have lots of theory and simulation data,
 > examples for solid state
 > tesla coils.
 >
 > Dan
 >
 >
 >
 >
 >
 >
 >
 >  > Just a thought.. Anyone else have any thoughts? I'm
 > not too
 >  > up to date with SSTC driver circuitry..
 >  >
 >  > Coiling In Pittsburgh
 >  > Ben McMillen
 >  >
 >  > --- Tesla list <tesla-at-pupman-dot-com> wrote:
 >  >  > Original poster: "george hadle by way of Terry
 > Fritz
 >  >  > <twftesla-at-qwest-dot-net>" <ckreol1-at-yahoo-dot-com>
 >  >  >
 >  >  > hi, My driver circuit its an ignition coil driven
 > by a
 >  >  > FET protected by schottky diodes.
 >  >  > The problem has several symptoms, all independent
 > of
 >  >  > the TC being connected or not.
 >  >  > If I short the hv terminal to ground, the circuit
 >  >  > completely ceases output.  It can spark between
 > these
 >  >  > two terminals without problem, its only when
 > directly
 >  >  > shorted it messes up. Whether the output is latched
 > ON
 >  >  > or cut OFF, I think its latched ON.
 >  >  > I'm running it at audio freq. and the sound of the
 >  >  > coil completely stops.
 >  >  >
 >  >  > I can rectify the problem for a few seconds one of
 > two
 >  >  > ways.  Turning off and back on.  Or changing the
 >  >  > frequency of the FET driver, which is a schmitt
 >  >  > trigger oscillator.
 >  >  > any ideas?
 >  >  > thank you very much
 >  >  > george
 >  >  >
 >  >  > _
 >