Re: 304tl experiments...and SSTC plans

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: Brett Miller <brmtesla2@xxxxxxxxx>

Steve,

--- Tesla list <tesla@xxxxxxxxxx> wrote:

> Original poster: "Steve Ward" <steve.ward@xxxxxxxxx>
>
> Hi Brett,
>
>
> >  It certainly won't be a
> >matter of just plugging in a standary SCR with a
> 555
> >oscillator on the gate.  I think one of the 1000v
> 600a
> >IGBT bricks would be sufficient, probably overkill
> for
> >that duty.  Plus, the driver circuitry wouldn't be
> any
> >more sophisticated than the usual staccato.
>
> Such an IGBT is completely wrong for this use.  It
> only needs to run a
> few amps, but possibly very high voltages.  The
> proper way of
> controlling this would be control of the grid.  Let
> me give it some
> more thought later...
>
> Steve

Steve,

I was making some pretty sweeping assumptions up
there, partially based on John Freau's report of using
1000V 50A SCRs for staccato on his vttcs, such as the
IR  50RIA120.  Anyway, thanks for reminding me about
the possible high voltage peaks between the cathode
and ground.  I would hate to waste a nice IGBT which
could be used in my future DRSSTC projects.

I guess the question would be:  Is a more
sophisticated vttc interrupter really worth the time
and energy to develop?  I guess I could only say yes
if it were elegant and not much more complex or
expensive than the current zero crossing staccato.

Realistically, I am personally going to spend most of
my free time on SSTC's and learning DRSSTC topology
these days.  I was just hoping to stumble upon an
interface that would allow me to just plug in a simple
555 sstc interrupter to my tube coil and dial up
various spark characteristics (within the tube's
switching limitations).

In other subjects, Steve, I have started on my half
bridge SSTC.  I found a nice big heatsink for the
fets, which should allow me to run at higher power
levels.  Also, I wound my first 30awg secondary.
Right now I am using it for the micro (single MOSFET)
coil.  It is 8" winding length and 3.5" diameter.
I'll probably wind a 4.5 x 11-12" soon if there is
enough wire left on the spool.  I am really looking
forward to the half bridge IRFP260N coil.  After that
I'll probably expand it to a full bridge, then start
getting serious about designing my first DRSSTC.

Cheers,

-Brett



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