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posible new vttc driving circut, advice needed and greatly apreaciated



Original poster: "marc metlicka by way of Terry Fritz <twftesla-at-qwest-dot-net>" <mystuffs-at-orwell-dot-net>

 Hello all,
I've been rebuilding my vttc tube circuit because i seemed to have
turned my twin vt-127a unit into, at the least, a double neon bulb unit
with blue\violet glow within the whole envelopes. At the most I think i
x-rayed myself and all of the lab when this ominous glow appeared
instantaneously? At least the filaments burnt open within a minuet or
two of my stunned gaze (I need x-ray badges).
 I don't to this day understand what my mistake was, but hope it was
just a nice neon display?

 Anyway, I've built a board of 1\2" lexan with four 4-125's, wired so i
could series all tubes, or separate two and two for future work. I've
only succeeded in mounting the tube pins through the lexan I use "little
fuse" holders to clamp the pins an solder to them) with the air transfer
holes lined up nicely for cooling. I plan on using oil lamp chimneys for
tube covers to direct airflow from through the ceramic base and up
around each tube?
 At first i would like to get the vttc running as normal using david
trimmels design.
Once this is done i have an idea to try using a light dimmer unit to
control the grid action to try to get 120bps variable duration (not sure
how this will work, but i've  also considered mounting a power
darlington transistor that would switch the grid via the dimmer unit.
Since a change out of 48 nte98's from a variable frequency drive, I have
a surplus of both these and many MJ11032 Darlington's.
 
 My question to the list is, does anyone see a problem switching the
grid circuit with a low break rate from the dimmer?

 I'm hoping to use the standard primary\tank cap system and hoping the
slow break rate will allow the tank to charge from the plate with maybe
a straight mot or a 2400vpt  voltage controlled with a variac and
voltage doulbler to get the 3kv-4kv to the plates? energized , and then
when switched off I'm hoping the tank energy will transfer from primary
tank to secondary output? I'm afraid of backlash or flash over so i have
many chokes and inductors, but not sure how to build the driver
protection circuit? 

 I'm hoping for best case scenario being a lower loss switching then a
spark gap? With the dimmer mounted with large "I" triac things will hold
for at least a few runs at first along with the 20 or 50 amp
Darlington's.

 I have the tubes mounted with cooling and a beautiful small\long
squirrel cage fan that will pressurize the 4" pvc air duct for cooling
up through the tubes. The Darlington's should switch any V\I that the
grid will supply until switched, i hope.

 What i don't know is how to config and choose capacitance's, I have
many many caps to choose from, I also think the main tank cap would need
to be matched to the primary inductance's, and will each pulse resonate
at the coils natural fr?

 This project came to me while laying in a hospital bed so it could just
be medication induced, but the tubes are mounted and i'm ready to start
the driver and tank circuit now (i can send picks of what i have so far
with an extensive list of caps and chokes or inductors to those
interested.
 I don't know if this has been tried before, but if not it my be one
other tc config to experiment with. I am excited non the less that i may
be able to control trigger time and duration of the grid.

If any of this sounds like bunk, I plead for scientific scrutinization
with no hard feelings beeing presented.
 I move forward with the things i know and will post any results as they
happen,
Take care, thank you
Marc M.