RE: Gap electrodes

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Pete Komen by way of Terry Fritz <twftesla-at-qwest-dot-net>" <pkomen-at-zianet-dot-com>

In my experience, brass balls make worthless spark gaps.  The spherical
shape causes the arc to jump at the same place all the time.  The brass
erodes, a tan deposit builds up, and performance drops quickly.  Brass
drawer knobs are not all solid brass... I had some that had a thin hollow
knob pressed onto a solid pedestal.

If you can make brass balls work, that's great.  I have switched to a vacuum
gap using copper pipe and I'll try a triggered gap as soon as I can.

I built a Terry triggered spark gap controller and had a interesting thing
happen.  When I plugged it into my isolation/variac controller (1kva
isolation xfmr, variac {120V max}, MOVs, 10 amp aerovox filter), the fault
light lit up.  I checked what I could and apparently the capacitive coupling
through the filter lit the lamp.  By shorting one side of the output (it's
isolated from the 120v from the wall) I could cause the fault light to go
out or get brighter.  Voltage measured about 60v from either side of the
plug on the isolation/variac controller though the current did not even move
the needle of a 5 amp AC meter.

Regards,

Pete Komen

-----Original Message-----
From: Tesla list [mailto:tesla-at-pupman-dot-com]
Sent: Saturday, August 11, 2001 2:23 PM
To: tesla-at-pupman-dot-com
Subject: Gap electrodes

Original poster: "The Big Giant Kevin by way of Terry Fritz
<twftesla-at-qwest-dot-net>" <neo4s-at-hotmail-dot-com>

Iv been using dresser drawer knobs for spark gaps. They're about 1-inch
diameter spheres, brass, and since they have a screw on the back, they are
very easy to adjust (just turn). They cost under $3 each at the hardware
store. They were nice and shiny until I ran some current through them, now
there oxidized and pitted. Other than that they work really good.

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