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8" first light! (real light)
Well, over the weekend, as promised, I fired off the 8" coil. 12/150
tranny bank, 35 then 80nf tank cap, nice shiny new primary, and a new SRSG.
My result, ~4.5' arcs till the form flashed over internally. Again.
Already fixed that once. Sooooo, I'll convert it all to external wiring and
try it again Tuesday. But on the runs I did get :) ) The gap was a little
off at first, and I had to fiddle with it till it ran nice & smoothly. I
have a static gap in series with my rotary, and as a result the electrodes
have to be lined up a bit closer to fire. Nothing a quick twist of the disc
on the arbor didn't fix. Now, with the gap running smoothly, I set about
tuning. The toroid is too small (as I'd figured...), so I constantly got
2-3 streamers. Strikes to a grounded rod were -at-~4.5'. ~4' streamers to
The secondary is ~1279 turns of 26 ga wire, making it ~8x25. Primary is
~100' of 1/4" tubing. I know the system can do better, once I get the
tricky flashovers fixed. But, most of all, the sparkgap is of interest to
I had my doubts that the tranny could charge up a cap that big. 80nf is
a big 'ole honkin cap. But it did, and it ran very smoothly (aside from
dimming the house lights! I gotta dig up same PFC). But the difference in
the spark gap current was instantly obvious. Instead of being a nice loud
brap, this sounded like a nice smooth chain of shots or small explosions.
Plus, the light changed from a bright white to take on a greenish tint
(maybe the brass electrodes frying?) But at any rate, my poor brass
stationary electrodes are eroding away at record speed. Time for beefier,
heavier brass rods.
So, hopefully Tuesday night, after I work on the secondary, we'll have
good long sparks. I photographed the coil workings (gap, caps, etc), and am
just waiting on the coil to be running strong. Got my tripod, ancient (read
excellent!) manual-everything camera. Fstop of 2.8 and 4 sec exposure on
400 speed film. 5.6 at 3 seconds, right?