Lego and other HV things

[Gene & Debby Stopp]

I just *have* to add to this thread... nothing about synthesizers, I admit,
but in the true spirit of electronic DIY...

A couple years back I was introduced to a guy who had built his own Tesla
coil that is 2 stories tall. When I learned this I asked him, "What did you
use for the primary winding, copper pipe?" to which he replied "Yes!". I
was kidding, he wasn't. Here's the technical details, as I remember them,
so hopefully if he reads this he'll forgive me (he does build DIY synths
too but isn't a member of this list as far as I know):

14KV-220VAC mains stepdown transformer run backwards, into a HV rectifier
to produce 25KV D.C., through a rotating disk interruptor into about five
turns of 1-1/2" copper pipe wrapped into about a 4-foot diameter primary
coil, which sits below the secondary coil made from 14-gauge HV wire of
many turns. The form for the secondary coil (and the basis of the 2-story
structure) is a cylindrical plastic underground liquid storage tank. At the
top (the "business end", as I suppose it could be called) is a central
aluminum sphere a couple feet in diameter surrounded by a bunch of
identical spheres in a circle. He told me once that a torus is the best
shape for the top of a coil, but he couldn't have one built, so he
approximated a torus with a ring of spheres. A sideways-pointing whip
antenna could be added to direct the discharge in a particular direction
since the HV tends to dissipate in a random pattern if left un-directed
(humidity and wind allowing, I suppose). The whole mess was carted around
in a big custom trailer with a hydraulic lift. He made money from this, I
think mainly from the movie industry which used it for lightning effects
(the beginning of "Terminator 2" being one of his gigs).

I witnessed the thing in action once - it was in a movie prop storage lot
in Marina Del Rey. I was cowering behing a forklift about 75 feet from it
as it zapped the corner of a nearby metal warehouse with about 30 feet of
lightning bolt. I remember describing the sound as "like a house being
sawed in half with a giant buzzsaw". The sound echoed off of the local
mountains.

Yes, the police showed up.

- Gene

p.s. I've been on vacation for a couple weeks, and I intend to post an
ASM-1 update tomorrow ( I need to sleep now, jet lag). I do have about 40
still available.

----------
> From: Mark Pulver <mpulver at midiwall.com>
> To: David Halliday (Volt Computer) <a-davidh at microsoft.com>
> Cc: synth-diy at horus.sara.nl
> Subject: RE: Lego and other HV things
> Date: Friday, June 27, 1997 12:29 PM
> 
> 
> >For a really big Jacob's Ladder, a Tesla Coil builder in St. Louis, MO
> >used a power pole transformer - he originally got it for driving his
> >*big* coil ( producing arcs 15'+ in length! ) but he sent me some video
> >of it running as a Jacob's Ladder.  Used 1/2" flexible copper pipe for
> >electrodes extending five feet above the xformer.  
> >
> >Made a sound like a bass wolverine in heat.
> 
> I think what amazes me the most about this is "how does one go about
> getting a power pole transformer, and just where do you get the 480(?)
> needed to drive it?" Can you really call the electric company and say
"hey,
> I need a 100 amp 480 run to the house".
> 
> :)
> 
>
---------------------------------------------------------------------------
>  Mark Pulver - http://shoga.wwa.com/~mpulver    The "Son of The MIDI
Wall"
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