Re: ISEF display
before you go and build this puppy, you better be certain you will be alowed to
use it. From what I remember of the ISEF rules (I did the science fair thing
back some years ago) you cant use more than about 20v, unless it's properly
insulated per some national code. I'm not sure what code would say about
insulating a 200,000 volt source of harmonic rich AC, but i'm sure the safety
inspector at the fair will raise an eyebrow from the neon sign transformer, let
alone the coil. Another part of the rules included a clause that said there can
be nothing distracting or offensive. even a small coil makes a heck of a lot of
noise, so you might get complaints there. Also coils through off ALOT or RF
interference. An ISEF has one of the highest 'packing desnities' for electonic
and computer gear I've ever seen outside of an electronic and computer gear
trade show. You might run into problems there to... I don't want to be a stick
in the mud, but I just thought I should let you know about potential problenms
you may have...
Tesla List wrote:
> Original Poster: "Jim Lux" <jimlux-at-jpl.nasa.gov>
> > From: Tesla List <tesla-at-pupman-dot-com>
> > To: tesla-at-pupman-dot-com
> > Subject: ISEF display
> > Date: Sunday, March 28, 1999 6:18 PM
> > Original Poster: jeremy sweeney <cyberjer-at-inetone-dot-net>
> > Greetings,
> > I qualified this weekend to go to the 1999 ISEF. Part of my project
> > involved a Tesla Coil, so I wanted to build a small one for my display.
> > have built small and large TCs before, but this one will be a little
> > different than I am used to. Since putting a grounding rod into the
> floor is
> > not an option, is there some way I can do a virtual RF ground?
> For a small coil, a metal sheet on the table top or hardware cloth or
> chicken wire (aviary netting) should work. If it extends about as far out
> as the coil is tall, it should work just fine (i.e. a 1 ft high coil in the
> middle of a 2 ft diameter plate would work). BTW, I've run a 2' high coil
> off a 30 mA NST with no grounding other than the third wire with reasonably
> good results.
> Also, I'm not
> > going to have a lot of free time between now and then, so any
> > for some really cheap capacitor sources?
> 1) Surplus, obviously
> 2) doorknob caps... 40 kV at 2700 pF is a commonly available value, and a
> pair will get you just where you need to be. About $20 each at the higher
> priced surplus places. Or, brand new from RF Parts in San Marcos CA...
> I'm going to use a 15 kV 30 ma NST
> > and a 5.31 nF cap. Thanks.
> Built one at that size in a day about a year and a half ago. Two 2700 pF
> doorknobs, dryer duct/pie pan top load, about 10 turns in a pancake coil of
> 1/4" copper tubing, secondary was 2 ft long on 4" pvc pipe with #20 ga (?)
> wire and a double static gap using 1" copper pipe chunks about 2" long and
> a muffin fan blowing through the gap. Works like a champ... Noisier than
> all get out...
> > Jeremy :-)