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Re: Ross-O's 1st Run - secondary arcing
to: Ross
Would suggest checking your coeff. of coupling. With a 6 inch dia coilform
you should be able to go to a flat spiral for the primary and still hit 0.2
for k value. Your 45 degree pri is probably overcoupled plus as you
noticed the corona can slowly start to degrade the insulation. A camera
with a 4-8 sec time exposure at f1.4 will reveal the intensity of the
corona most of which is invisible to your eye.
Dr.Resonance-at-next-wave-dot-net
----------
> From: Tesla List <tesla-at-pupman-dot-com>
> To: tesla-at-pupman-dot-com
> Subject: Ross-O's 1st Run - secondary arcing
> Date: Sunday, February 07, 1999 8:23 PM
>
> Original Poster: "Ross W. Overstreet" <ross-o-at-mindspring-dot-com>
>
> I made my 1st run of Friday night. I managed 31" arcs to a grounded rod
> before secondary arcing convinced me shut down. Here are the specs for
> my coil along with my Tesla URL. Please forgive the large pictures and
> slow loading of the page, I'm working on it...
>
> Primary: 15 turns of 1/4" copper tube with 3/8" spacing on a 45 degree
> angle
> Secondary: 6.275" SDR wound to 25.1" with #22 magnet wire
> Capacitors: .060" LDPE rolled cap, used .027uF for this run
> NST Bank: 12 kV -at- 106 ma
> Torroid: 7" aluminum dryer ducting, total OD is 29.5"
>
> See the page for pics and more details
> http://www.geocities-dot-com/CapeCanaveral/Cockpit/3377/
>
> I only managed to tune to the nearest turn before secondary arcing
> forced me to shut down. I had a heavy blue cone of corona from the top
> turn of the secondary down to the strike rail. It looked neat, but I'm
> afraid that the excessive ionization around the secondary may have
> facilitated the arcing problems. The 1st arcs originated from a
> "fisheye" in the varnish about 6" from the top of the secondary and shot
> straight down the coil to the ground connection. I put a couple layers
> of electrical tape on top of the bad spot and kept running. I noticed a
> few more of these coming from other locations. I raised the secondary
> about .75" and got a different sort of arc. This one came from the top
> turn of the secondary and only went down about 6". It formed a large
> brush shape almost as large as your hand. I quickly surrendered for the
> night.
>
> The good news is the 31" arcs while still somewhat out of tune. I was
> able to light a neon "R" at about 10' and could make a 4' fluorescent
> tube glow over 20' away! It's a beautiful thing - the sound, the light,
> the smell, all of it! Guess you could say that I'm thoroughly addicted.
>
> I had a hard time getting breakout without using a sharp point. I
> managed it twice before I shut down, and both times it came from the
> rough seam of the torroid. It seemed to prefer to break out on the
> secondary instead of the torroid!
>
> I fear that I may be overcoupled with the 45 angle on my primary. I can
> raise the secondary if I need to. Maybe I need to lower the torroid or
> make it smaller? I could get rid of several turns of primary and drop
> the ground rail several inches to help reduce the corona cone. I am
> really excited about running this thing again and could use some advice
> from you experts on how to solve this problem :-)
>
> I really want to thank all of the people who contribute to this list,
> especially the moderator (Hi, Terry) and the TCML webmaster (Hi, Chip).
> I have learned tons from this list and the archives. You all have also
> provided much needed inspiration during the sparkless months. The
> internet is a truly beautiful thing!
>
> Feel free to respond off list to <ross-o-at-mindspring-dot-com>
> Constructive criticism always welcome.
>
> Ross Overstreet
> Huntington Beach, CA
>