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More DRSSTC magnifier work

Original poster: Steve Ward <steve.ward@xxxxxxxxx>

Hi Guys,

Over the past few days i got to work on my big project ;-).


The construction is going smoothly there.  Should see some spark
action this weekend, but i might have to limit things since last time
i ran the big coil, a stray power arc (about 6' long) really latched
onto the side of the house and this killed 1 network card and a port
on our router.  The voltage on the toroid is usually low enough, that
dispite making 10' sparks from the breakout, it usually wont arc
nearly half that distance directly from the toroids side to anything
else.  Well, once it did arc, i turned the coil off and a moment later
my brother comes down to tell me the internet just went out.  Oops!

But in any case, the magnifier should let me move the sparks well away
from the house.  We shall see what happens there...

I also did a bit of work on the first magnifier, seen here:


Just some general construction work to tidy things up.  Today i did a
few more experiments with that coil.  I was varying the K and primary
tuning (both L and C).  I found an interesting trend, but it makes
sense.  Lower K requires a higher primary tuning.  Higher K requires a
lower primary tuning.  Both scenarios can be made to produce "long"
sparks (36" or greater) but the higher K seems just slightly more
efficient, but the increase in efficiency is much smaller than i
anticipated!  The range of K's i was comparing were from about .2 to
about .4, and this is just the K between the primary and secondary (so
the overall K is lower).  So it seems like i was somewhat wrong about
my previous assumptions that the highest K possible was always the
best.  Seems lower K works ok too, but probably not too low, or else
the transfer time gets much to long.

I also looked into the notched tuning again.  I found that spark
production was always best when i cut the bang at a notch.  Limiting
to 2 notches only got maybe 18" sparks at about 350W input.  Opening
it up to more notches and the current grows to 400A (which is where it
would be if running with a lower tuning) yet the sparks dont get much
longer at all.  Just doesnt seem to work well...  Sticking with a
lower tuning i could get 36" sparks with 530W or so.  I seem to
remember it being more efficient in a previous experiment, i will have
to look at this some more.  My efficiency seems down, and i think its
mostly due to trying to squeeze every last bit of spark lenght out of
a small setup.

The other test i performed today was more of a destructive test.  I
allowed the tertiary to arc back to the transmission line (at full
power!).  There didnt seem to be any ill effect from this!  The
primary current went up only slightly, there was no other flash over
or anything like that seen.  This was something that needed to be done
in real life as im not sure i would be able to model it well enough on
the computer.  No IGBTs were lost, so all is well!

Steve Ward