Re: Inexpensive drawer-pull spark gap electrodes

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

Original poster: "S Gaeta by way of Terry Fritz <teslalist-at-qwest-dot-net>" <sgtporky-at-prodigy-dot-net>

I built a gap with the brass drawer pulls from Home Depot. I thought it
would be superior because it would cut down on corona losses. I found that
it was inferior to the copper pipe type gap. It would foul after a couple of
minutes of run time. My spark length would quickly die down, and I had to
turn the coil off and clean the gap elements with sandpaper to get the the
coil working right again. When I switched to the copper pipe arrangement, I
got better performance even compared to the freshly cleaned ball gap
assembly, and I only had to clean the gap every once and a while after
several runs lasting a few minutes. Even at that, I only did the cleaning as
general maintainance, and not because my spark length was noticeably
dropping.

I think those balls were zinc because the color was no longer brass where
the arcing and cleaning took place. By the way, those things also had a
varnish or clear laquer coating that had to be stripped off after I bought
them. Not that it would really matter because the arcing would burn it off
in short order anyway. I just didn't want the smell.

Sue
----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Tuesday, May 27, 2003 7:46 PM
Subject: Inexpensive drawer-pull spark gap electrodes


 > Original poster: "Scott Hanson by way of Terry Fritz
<teslalist-at-qwest-dot-net>" <huil888-at-surfside-dot-net>
 >
 > A note of caution on using the "cheapie" drawer pulls as spark gap
 > electrodes.
 >
 > All the inexpensive ones I have ever seen were die-cast zinc with a very
 > thin brass, nickel, or chrome plating. If used as electrodes in a primary
 > spark gap, the thin plating very quickly erodes away exposing the zinc.
The
 > zinc has relatively low vaporization temperature and develops problems
with
 > quenching as soon as the electrodes begin to heat up. The effect is much
 > more pronounced with 60ma or greater supply current.
 >
 > Solid brass brawer pulls are available, but are harder to find and are
 > considerably more expensive than the zinc ones.
 >
 > Regards,
 > Scott Hanson
 >
 > These work fine as safety gap electrodes, but
 > ----- Original Message -----
 > From: "Tesla list" <tesla-at-pupman-dot-com>
 > To: <tesla-at-pupman-dot-com>
 > Sent: Monday, May 26, 2003 6:23 PM
 > Subject: Re: Tuning Troubles
 >
 >
 >  > Original poster: "Dr. Resonance by way of Terry Fritz
 > <teslalist-at-qwest-dot-net>" <resonance-at-jvlnet-dot-com>
 >  >
 >  >
 >  > For great spark gap balls at a great price, go down to Home Depot in
the
 >  > cabinet section.  Look for the "drawer pulls".
 >  >
 >  > Specifically Liberty Hardware p/n P1061C-CHR-C.  It is approx. 1 1/8th
 > inch
 >  > dia. and has a chrome finish.  Very solid and comes with a mounting
 > mounting
 >  > bolt.  They also come in same size with brass finish.
 >  >
 >  > The great part is these balls are only $2.39 each!!!   You can make a
nice
 > 3
 >  > electrode, 2 gap, sparkgap for under $10!!
 >  >
 >  > Dr. Resonance
 >  >
 >  > Resonance Research Corporation
 >  > E11870 Shadylane Rd.
 >  > Baraboo   WI   53913
 >  >  >
 >  >  > Eight spark gaps may be wasting excessive energy in the form of heat
 > and
 >  >  > light --- especially heat.  You might try just one or two gaps for
best
 >  >  > efficiency.  On most of our 30 mA and 60 mA coils we use just three
1/2
 >  > dia.
 >  >  > tungsten electrodes to form 2 sparkgaps.  Only on the 60 mA units do
we
 >  > add
 >  >  > a 100 CFM fan behind the gaps.  30 mA doesn't require any cooling at
 > all
 >  > for
 >  >  > best quenching.
 >  >  >
 >  >  > Also, experiment with elevating your sec. coil in 1/2 inch
increments
 >  > until
 >  >  > you hit the best coeff. of coupling.
 >  >  >
 >  >  > Dr. Resonance
 >  >  >
 >  >  > Resonance Research Corporation
 >  >  > E11870 Shadylane Rd.
 >  >  > Baraboo   WI   53913
 >  >  >  >
 >  >
 >  >
 >