[Prev][Next][Index][Thread]

Gadzooks, sparks are pretty

Subject:  Gadzooks, sparks are pretty
  Date:  Sat, 14 Jun 1997 15:03:25 -0400
  From:   Michael Bauer <mbauer-at-execpc-dot-com>
    To:   tesla-at-pupman-dot-com


        I just got back from taking my coil out to the country whar I
wouldn't bother the neighbors.  I started out with 1 inch of vertical
spacing between the primary and secondary.  I was watching for
overcoupling
from arcs to the middle of the coil, but it was really was arcing from
the
bottom secondary turn up to the side of the coil several inches.  I
raised
the coil by an inch at a time and it progressively reduced in intensity
and
disappeared at 5 1/2 inches lift.  I never did see any primary to
secondary
arcing.  As a refresher, my secondary is 20" by 40" on a wooden form
with a
6 X 30 toroid.  The primary is 9 turns of 5/8" copper with a 0.1 uf/40
Kv
capacitor, rotary gap, pole pig, welder ballast.  the one big mistake
was
that I only had a 20 amp breaker in the wall and I kept blowing it.  I
had
to keep the power low, about 25-30 amps on the meter to get a little run
time.  Even though, I had consistently 6 foot sparks!  I had more room
on
the variac and on the welder.  
        Best spark output was about 2400 RPM on the rotary with 12
posts.
Any higher, and the current limit didn't allow the caps to charge up
high
enough.  With extra line filter, I was able to keep the SCR motor
control
working without failure.  Speed control was never a problem.  I also
added
60 amp RF line filters between the pig and ballast to keep RF out the
control cabinet and off the mains.  The electronic meters I built also
keep
working.  I use analog meters with op-amp front ends and buffering to
the
scope.  The current bounced around way too much as the secondary strikes
changed for digital meters to be read.
        Dr. Resonance is right that I need more toroid load.  The arcs
were
fast moving and thin.  A larger toroid would concentrate these into
thicker,
slower moving strikes.  I need to make a run to the hardware store this
week
for toroid parts and larger breakers fro the mains.
        I couldn't wait for nightfall to come the last few days to run
the
coil.  Daytime sparks just isn't the same as nighttime.  Next week my
wife
will also come along up to our other place to see the show and see that
all
my hard work has paid off.  But what the heck, she could care less about
sparks.  In fact, she would rather have me painting the house.  
        So much to do, so little time....