Vacum gaps and variacs

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Original poster: "jpeakall by way of Terry Fritz <twftesla-at-qwest-dot-net>" <jpeakall-at-mcn-dot-org>

Howdy all,

In response to the recent thread about varying vacum strengths, I hooked up
my Gary Lau style gap to a variac. I use a 5hp shop vac as the vacum source.
I found that indeed full power was reducing my spark by about 15-20%.
Somewhere in the range of 65vac seemed best, although as my power does drop
when I run my coil, I'm not sure what the voltage really is when the coil is
running. 'Cause I ain't gonna turn on my DMM and find out!

Interesting to me, as when I tried my dual ignition coil powered TC on the
vacum gap some time ago, it performed poorly. I wondered about that. Is it
that some ionized air is needed, and the gap quenches too soon?

Gotta love the things ya learn around here...

Jonathan Peakall