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Re: SISG - PIRANHA Tesla coil first light! (and other claims)

Original poster: "Mike" <mike.marcum@xxxxxxxxxxxx>

Going from memory (this was Holloween 2001) , the secondary was 8x40 wound with 1500-1600 turns (didn't count) with 22awg. topload was 30" sphere similar to 20" ones found here: http://www.lawnornamentsandfountains.com/index.asp?PageAction=VIEWCATS&Category=698&SetPageSize=25 (the 2 30" ones I have were given to me the previous xmas for a vdg I never got around to building). It had a 1" copper ring 12" outer diameter below it to keep arc's off the top windings. Also needed a breakout point (1" rare earth magnet cube was handy) before the upgrade. The primary was 3/8" copper tube 3/8 apart, 12 turns, with I think 1" inner spacingfrom the secondary. Coupling measured with a plain old dmm came to around .14-.15. I never did get the .22 I was trying to get, thought that was a value to shoot for as I was building this going by Brent Turner's Tesla Coil book (didn't know this list existed at the time), now out of print I think. Cap was .045 uF 70kV bank made from 2x3 array .03 uF 35kV maxwells (was going for $50ea at the time from ebay). Old cap was a big landfill's worth of salt water and clear beer bottles (probably 150 of em, had more time than money when I started) in aluminum cake pans (I think) that kept cracking randomly after 3 min runs. SRSG was a 12" disc on an 1800 rpm (after new caps I also switched for a 3600 rpm motor) that had 4 flying brass acorn nuts and 2 stationary on either side of the disc (short conduction path) made from a block of brass with rather large heatsinks from my junk box bolted on. Phase was adjusted by a shielded gear motor (1 rpm) that rotated it +/- 45 degrees (never needed that much tho). Power supply was 2 15/60 nst's unpotted with the shunts left in and put in mineral oil (thinking this would make them more bulletproof). Variac was 20A 0-140v. I think it pulled almost 21A even with 175uF pfc with the variac turned all the way up, but 20A breaker it was on didn't pop (well, not much). Right now the coil is at my cousins across state. After I moved to an apt I didn't have room for it, and since he did most of the work (he's a machinist more than a coiler, at least before I intro'd him to the hobby) I let him have it. I haven't talked to him in awhile, probably see him and his family during thanksgiving and I'll see what old pics I can dig up/scan. His parents (that he still lives with sad to say) are scared to death of it (my little accident didn't help), so not likely it'll be dug out of the barn there for a power up. It's been stored there for past 3.5 years. The aftermath of the zap I got is now a whitish pit big enough for a 1/3 of a pea to fit into. Not real bad, but bad for an electrical burn 5 years after the fact. At the time it was a roundish burn (not all black, but burnt enough that it had a few wisps of smoke off it and melted part of my shirt to it). I was dazed/pale for a few seconds (basically got shocked silly), but my cousin that helped build it was there and he freaked and took me to the hospital. They did the usual ekg/physical (zap was on left side, not particularly good for the heart) and gave antibiotics to keep the burn from getting infected. Half my big toenail eventually detatched/grew back where the spark exited. Left a whitish burn on the left side of my right toe. I hindsight what caused all this was not paying enough attention/coiling while tired: I didn't notice I had the variac full blast after the upgrade when I plugged it in and stepped on the deadman switch and buy sheer fluke didn't need much fine tuning (the inductive kick probably helped as well). Otherwise I could have seen the sparks getting bigger and bigger and moved back.

----- Original Message ----- From: "Tesla list" <tesla@xxxxxxxxxx>
To: <tesla@xxxxxxxxxx>
Sent: Monday, August 28, 2006 9:05 AM
Subject: Re: SISG - PIRANHA Tesla coil first light! (and other claims)

Original poster: "Scott Hanson" <huil888@xxxxxxxxxxxx>

Mike -

WOW!! Eight-foot arcs out of a 120ma NST powered system is extraordinary performance, almost unbelievable. With a conventional spark-gap coil, this level of performance is usually obtained only with an over-driven potential transformer or a pole-pig.

Can you provde the detailed specifications for this coil? I'd sure like to try to duplicate this coil with my pair of 15/60's and see if I could obtain this performance level.

Dimensions of primary and secondary, MMC cap details (make & model of caps used, caps per string & number of strings used, total value, etc), toroid size, resonant frequency, details of the 240 BPS gap system, etc, etc. would be GREATLY appreciated. How much current was this system pulling from the 120 VAC outlet? Sounds like this coil is one for the record books. Certainly some photos are available? I'm sure that Terry would be happy to post them at Hot-Streamer.com.

What type of wound was produced when you got hit by the 8' streamer? Must have been pretty severe to leave a "nasty" scar years later. Did you require immediate medical attention? In 20 years of following Tesla-coil related subject matter, I can't ever remember a report where a streamer hit caused an open wound, so those of us with medical interests would appreciate the first-hand details.

Also, where did you obtain your 30" lawn-ball ornaments, and how much did they cost? These would be very useful for anyone building a Van de Graaff generator, and spheres this size seem to be extremely difficult to find.

Scott Hanson

----- Original Message ----- From: "Tesla list" <tesla@xxxxxxxxxx>
To: <tesla@xxxxxxxxxx>
Sent: Sunday, August 27, 2006 7:46 PM
Subject: Re: SISG - PIRANHA Tesla coil first light!

Original poster: "Mike" <mike.marcum@xxxxxxxxxxxx>

I once got hit in the shoulder by a 15/120 powered coil a few years ago when I switched from 120 to a 240 bps and a better mmc and underestimated the length increase (~4 to almost 8 feet, with the spark going from thin and blue to alot thicker and white). Left a nasty scar at he strike point. My big toe where it exited to the deadman switch still feels funny (more like doesn't have much feeling). Contact was probably an eye blink long (thanks to the switch), but forget the skin effect (common belief of the time), I felt every beat of the spark gap and that hurt like heck.

(From Mike's subsequent post:)

<Original poster: "Mike" <mike.marcum@xxxxxxxxxxxx>

"Was thinking of using 1 of those 30" steel ball lawn ornaments I have lying around to
make one whenever I can find some suitable 4-6" pullies (aluminum and
teflon hard to find), just don't wanna kill myself when I go to do
the hair-standing stunt."