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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
>