304tl

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: Sparktron01@xxxxxxxxxxx 

SNIP

This reminds me.  I had an idea.  What about using an
interrupter with a suitable SCR, with some good
isolation between the SCR and the interruptor.
---------------------------------------------------------------
Brett

You need to use a controlled switch like an IGBT,
a SCR will require cathode current to drop below
latching current values (i.e. a current '0') to allow
the current to be controlled.  An IGBT can pretty
much be turned on and off as necessary, as long as
you don't exceed Vce; controlling currents will
be trivial (<5A for all but largest VTTC).  You could
could control screen grid bias on 4PR style tubes
and drop controlling current  requirements
another order of magnitude.

I have considered breadboarding the same type
control (Hyper-staccato???   ;^D )  Basically power
supply could be filtered DC or an AC level shift
power supply.  You gate oscillator on as normal
burst controlled staccato but you terminate
oscillator burst when cathode current exceeds some
value, rest tube for some time (.5-2ms) then repeat.

A "POP-POP-POP--rest--POP-POP-POP-rest-POP-POP-POP
-long rest- REPEAT sort of sequence.  Each POP would
be similar to present DRSTTC systems (50-200us
depending on resonant frequency, and oscillator
build up time to current limit.  Number of POPS in
pulse train, rest times (intra POP and burst long rest)
could be programmable via a PIC or FPGA style
controller.  This control method is identical to present
PIC, uP controlled DRSSTC systems, but implemented
on a VTTC.

To my knowledge, such a modulation "recipe" has
never been attempted (at least in public domain)
on a VTTC system.

SNIP

-Brett
-----------------------
Regards
Dave Sharpe, TCBOR/HEAS
Chesterfield, VA USA