Hi all,
I am going to start by referring to this just posted thread for related
background info and the recent ideal I had to borrow my VTTC Staccato
controller and again using a SSR.
See thread:
VTTC Staccato/Interrupter Controller modified so SSR is useable for LShPS
So a little background on this SGTC first:
This is just a simple standard SGTC that my father, my brother and me put
together originally back in the early 1980's. It ran just okay back then
for what we knew then. Originally also used a very large homemade single
glass plate capacitor, which was very lossy. But it was cool seeing the
corona losses surrounding the metal plate edges on the glass all around...
quite the glow!!!
Not going to go in all details...but several years ago I dug this fella out
from storage. After some mishaps..me and my Dad decided to "modernize" this
fella to things known now. Decided to make a MMC bank using the favored CD
poly caps.
Add a Terry-Filter. Got some .25" tungsten for a dual static spark gap.
Upgraded to a 15 kv 60 ma NST from a 30 ma. Add a 12" toroid. Reused as
much as I could original wood rings primary supports and use .25" copper
tubing and some ceramic rounds supports, instead of the original heavy
insulation wire it had and the wood rounds supports. "Borrowed" a parts bin
for a spark gap cover and put on two large 120vac fans on to mostly help
cool gap, get clean air in and maybe just help a little on quenching. 4"
dia. secondary was unchanged. It is wound on a piece of house carpeting
cardboard tube if I remember correctly. It was varnished inside and out,
then wound and varnished again. It looked good still, so decided to use as
is. So this coil is a mix of new and old.
The layout of the separate MMC is intentional and extra inductance from
long leads was figured in some and other losses were accepted.
I want to be able to very easily break this down and nothing too heavy or
awkward to handle when handling. This then very easily fits into my small
little commuter car for easy transport.
So this was a just a little at a time project between several others.
Very recently got done finally and did the first relighting of this "new"
old coil. It went very well right out the gate. Decent sparks and with just
a little more tuning and tweeking even better output. Very happy with it
for the transformer we are using. Actually this "blows away" the original
performance of this coil in all the 1980's when we ran it last.
I will admit some it took some rethinking of things as tube coils are a bit
of different beast and I mainly mess with them now and had to get my brain
focused on this at times.
I want to also metion that this NST has GFCI. This GFCI is not potted in,
which is unusual now. NST is of course in potting. GFCI could easily be
removed and by-passed, but me and my Dad decided to leave in and try it as
is first. Well for us it is working just fine, so we are guessing the
Terry-Filter is possibly doing a good job. Since works fine with, we will
leave in for now...
So basically this SGTC runs just like any other on straight normal AC.
Okay on to the intent of this tread.
I have been spoiled for the past several years on my VTTC's.
I enjoy the near unlimited run times with the various Staccatos depending
on how you set and run these circuits of course.
On the SGTC anything past 2 minutes I started to get worried. 3- 4 minutes
was probably longest I was probably comfortable to run max.
Mostly 1 -2 minutes was most common and let cool down for a while.
I will admit, kind of hard to keep track of at times on how long running.
Seems like always a worry factor here.
NST was a quite warm after these runs. I knew static spark gaps probably
were hot too despite fans. I was not going to touch and find out. The MMC I
was not really worried about. It was always cool still to touch.
I got thinking again about the fairly recent modification I did to a German
kit Staccato controller for SSR cathode switching use on my 304 VTTC.
I thought about SSR's and their originally intended use switching on mains
voltage. So I rigged up a spare SSR on a heatsink to switch the hot wire on
the 120vac mains at the input of the NST. Going to switch the NST primary
direct. I then plugged in my German Staccato circuit on the "clean" side of
the big line filter we are using.
I am happy to report that this works wonderful. The SSR zero crossover
detection is working very well. Response of Staccato controller changes are
instant and smooth on any changes. Everything is staying cooler of course
as expected. The video in the link is quite long to prove this. NST was
just barely warm after 17 minutes, makes sense since transformer is not
constantly energized. SSR on heatsink barely warm. I have done several runs
over an hour each now. No problems. Just other night I did a almost a 2
hours run playing around. Still no problems.
Several interesting things can be done with the Staccato controller.
The PW is in most ways set the opposite of what a tube coil wants for the
longest arcs and this makes sense of course as a SGTC wants several
successive cycles to grow the discharges. It is interesting to change PW
but then change the PRF. Certain interesting "sweet spots" I have found so
far. So when I intentionally created these Staccato burst modes for the
VTTC, I thought this should work on the SGTC and does wonderfully.
It is interesting to bring SGTC to just a single PW cycle and slowly bring
up to maximum multiple cycles PW.
Hope this rambling makes some sense.
I will now let pictures and a pretty long video speak for themselves.
The sound is quite different at all the different settings. The microphone
on the camera is actually "overwhelmed" and does not truly capture all the
true sounds. There is a breakout point on the toroid on the trash can side.
Trash can about 3ft away for strike target.
Further tuning and testing is still required on this coil and now I am
starting to maybe consider this Staccato as a possible factor. The Staccato
can be a factor for tuning on a VTTC which I know very well.
I will have to see what happens eventually with more experimenting.
https://photos.app.goo.gl/sFgpX52MthRHH8X19
Chris Reeland
Ladd Illinois USA
Sent from my Samsung Galaxy Tab® S