Nice coil, Jeff ;-) An oil cooled, stationary SG is definitely a novel idea, especially for such a large and high powered system. As for your spark length goal, I would assume that the ~10 foot sparks with 30 amps or so input will be doable once it is properly tuned in. However, I would personally figure the 15 or 16 footers to be a little more "out of reach" if your ceiling amperage is 50 amps. Remember, the power requirements approximately increase as the square of the output spark length, per Freau's spark length formula - spark length (in inches) = 1.6, or possibly 1.7 x (sq.rt. wall plug watts) and this, of course, assumes absolute optimal fine tuning and maximum efficiency, so in most cases, the actual spark length will be notably less than this formula would suggest. Bottom line is that to double your spark length from a given coil pretty much requires a four-fold increase in power. Of course, YMMV.
I hope the museum is somewhere in the US as I could feasibly come to visit it. ;-)
David Rieben
Sent from my iPhone
> On May 16, 2014, at 8:27 PM, Jeff Behary <jeff_behary@xxxxxxxxxxx> wrote:
>
> I've been distant a year or more, chaos in life as I'm sure everyone has lately.
> But some may recall a large coil I started on my birthday last year. Its made for a major
> future Tesla museum (not Wardenclyffe) that I must refrain speaking about too much for the moment.
> It's personally dedicated to Bill Wysock, Harry Goldman, Kenneth Strickfaden, and the long list of other
> friends and pioneers in the field. Not meant to be the biggest or best coil on earth but something
> different...and yet the same. Powered by a 10KVA pole pig, 120/240 - 14.4kV single phase.
> .1 mfd 100kV cap bank. 2" flat ribbon and EPDM rubber primary coil. 10.75" x 75" secondary coil
> threaded 14 turns per inch and inlaid with 16 AWG wire. 48" diameter x 12" cross section toroid.
> The spark gap is a 12-series 1/2" tungsten oil-cooled gap, made to handle high currents. I specifically
> wanted something different here, as I know Bill and Harry would be amused to see such a drastic departure...
> (but its not so far off from early high power transmitter designs...just a little engine like :) ! )
>
> First light didn't happen when it should've (last weekend). Meant to run from 240V 50A...but I only have access to a 240V 30A line
> out in the country where I can safely test it...and my ballasts were consuming all of the current instead of limiting it...by poor pig
> was only putting out about 15mA, LOL, and I was still blowing the 30A fuse, talk about a kick in the butt after a long day of work...
> by the time I started tinkering with the power supply and figured out the problem it was late at night. Had spent 12 hours in the sun
> drilling 2" thick GPO, fun but not fun if you know what I mean... and it took us 2 hours to figure out how to get a 4 foot
> toroid 11 feet in the air for lowering it...don't laugh...its easier said than done! They're like picking up a greased aluminum pig.
> The good news my pole pig afterward threw white hot arcs instead of 1/2" blue sparks :/ !!! and still even at seriously no power to
> speak of I was getting 4' sparks. Hoping for at least 9-10 ft on 30A and 15-16 on 50A. Of course more would be better but this
> gap being stationary and higher powered (and low BPS) should make some nice slow hot arcs. Rain all week here, but weekend forecast
> is clear...so wish us luck tomorrow :) !
>
> I am really happy with the PVC tie rod made from 3" PVC pipe. The secondary coil keys in to holes on the base top and is screwed down from
> below using 1/2" bolts. At the top of the coil of course there is no metal. But the secondary coil weighs 75 pounds, is tall, and the 100 pound
> oversized toroid doesn't help matters. I didn't want any chances of it all falling over in the wind...
>
> The coil is horrifically heavy... in fact a 1/2 ton. When finished it must be OSHA compliant, no seriously, stop laughing. I can't
> give away too much, but it really will be. What I can assure everyone, is that the final installation site will be a place you all want
> to go. Regardless of the big coil... it will be Tesla paradise ;) ...
>
> http://www.electrotherapymuseum.com/2014/BigCoil/index.html
>
>
> Its not to typical specs, I didn't want such a large topload but the man paying the bill did and I didn't argue as there were two for sale.
> Terry I can't blame you for wanting to get rid of them. I had to rent a Hope Depot truck just to transport them to the test site, only to
> have my parents run their car battery flat. It took 3 hours and $100 to move them 20 miles...!!!
> Endless thanks to everyone who has "friended" me on Facebook, its so nice to see faces with names and how similar we all are at the end
> of the day...
>
> Jeff
>
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