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Re: Twintastic first light
Subject:
Re: Twintastic first light
Date:
Thu, 03 Apr 1997 15:58:15 -0600
From:
huffman <huffman-at-FNAL.GOV>
To:
Tesla List <tesla-at-pupman-dot-com>
Congratulations,
This is the kind of stuff I like to hear about. Keep up the interesting
work.
I have to visit your place some time.
Dave Huffman
----------
> From: Tesla List <tesla-at-pupman-dot-com>
> To: tesla-at-poodle.pupman-dot-com
> Subject: Twintastic first light
> Date: Thursday, April 03, 1997 2:44 PM
>
> Subject:
> Twintastic first light
> Date:
> Thu, 3 Apr 1997 14:34:52 -0500
> From:
> "Robert W. Stephens" <rwstephens-at-headwaters-dot-com>
> To:
> tesla-at-pupman-dot-com
>
>
> All,
>
> A while ago I mentioned that I was building a compact tandem Tesla
> coil system (my first). Several weeks ago on a very wet/foggy saturday
> nite I had it sufficiently finished to put power to it for low power
> testing
> up to about 3 kVA.
>
> Fellow list members Jeffrey Wiggins and special long distance guest
> Kevin Conkey were in attendance for this exciting session of first
> light. The coil absolutely refused to connect streamers between
> towers at first. This was a puzzle to me because I was *sure* I had
> calculated the handedness and thus the phasing of all the coils
> correctly before winding them. It seemed the more power I threw at
> the system, the more the streamers ignored each other in the common
> volume between towers. Just for fun I reversed the drive connections
> to one of the primaries. Bingo! Now we were cooking. I had in fact
> figured my handedness correctly, but has erred in the way I hooked
> the two primaries in series in the temporary lashup all over the lab
> floor.
>
> The secondaries are each 36 inch wound length of #18 AWG
> Polythermaleze copper magnet wire wound on 10.5 inch diameter,
> 5/16ths inch walled PVC pipe. The secondaries are of identical wind and
> each measure 50 mH. The prmaries are opposites, mirror images of each
> other employing 7 turns each of 5/16th inch soft copper refrigeration
> tubing in flat spirals. The secondaries are embedded about a full
> inch into the flat spirals yielding a measured K factor of 0.18.
> With the new, large 10 inch cross section x 35 inch toroidal toploads
> the
> system tunes about 100 kHz at about 5 turns on each primary. System
> cap is a 0.05 mfd.
>
> For first light only 1/2 of the center tapped secondary, 9 kV worth
> of my 4.5 kVA oil filled transformer was used to limit the voltage to
> the 35,000 VDC rated pulse cap. A safety gap was placed across this
> cap with a gap setting of 1.125 inches. It fired often during some
> of the tests approaching 3 kVA. Small toploads were installed being
> stacked
> 25 inch by 3 inch smooth commercial rings spaced about 8 inches apart
> thus
> creating a larger 'phantom' terminal. My larger toroids planned for
> the system had not yet been fabricated and I was eager to plug the
> sucker in! : )
>
> With a heavy fog swirling airborn water droplets outside the lab and
> relatively high humidity in the lab the system was powered up after a
> quick instrument tune employing about 3.5 turns on each primary.
> Jeffrey assisted with a few low powered runs into bleeder points
> while we moved the primary taps around a bit attempting to find the
> *sweet spot*. Once found, merely 2500 VA
> input was making tremendous solid connecting streamers between the
> towers with a distance of 7 feet 9 inches between terminals, and no
> bleeder points. This is a witnessed accomplishment also recorded on
> videotape by Kevin C. This is my best power/distance Tesla coil
> achiement to
> date!
>
> Since then I've finished the new bigger toploads and with a higher
> voltage capacitor have been able to wire in the full 18000 volts of
> the transformer. Now at 7500 VA I am making a great show with the
> terminals spaced at 132 inches (yes 11 feet), all underneath a 10 ft
> 4 in metal ceiling. This successful, exciting twin system is going on
> permanent display in the 72 seat electricity theatre I'm now building at
> home.
>
> Check this out for yourself, two jpegs of 7.5 kVA operation at 132 inch
> terminal spacing are attached. twin1rws.jpg is with smooth terminals.
> twin2rws.jpg is with very tiny pieces of adhesive aluminum foil tape
> stuck to the terminals with a corner lifted about 1/8th of an inch,
> just enough to help concentrate the streamers towards the opposite
> tower. Although these pictures were taken with very low humidity in
> the lab, a condition which I consistently find gives me LESS
> performance per VA, some of the photos from the session show
> streamers from each tower reaching out as far as 8 feet to connect
> with stuff in the room. That's about 2.7 times the individual
> resonator length. I can't wait to push this sytem outdoors and turn
> it up to eleven! : )
>
> rwstephens
>