RE: New bipolar

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "David Thomson" <dave-at-volantis-dot-org> 

Hi John,

If you really want to build an authentic Nikola Tesla bipolar coil, check
out this coil on one of my pages.  The coil itself belonged to Nikola Tesla.

http://www.tesla-coil-builder-dot-com/double_cone_bipolar_tesla_coil.htm

It is wound on a plywood form.  The plywood form is made by cutting circles
of decreasing diameter and stacking them, then turning the whole unit on a
lathe.  Each cone is 6" across the base and 6" in height.  The wire is a
cotton twill over solid copper wire.  The wire appears to be between 20 and
16 gauge.  I'll mic it if you need it.

The history of this coil is that an FBI agent passed away and some guy
bought it from his estate.  That guy sold it on eBay.  The other bidder I
was bidding against (I didn't know it at the time) had the empty forms for
this coil already made up.  His father received the form pattern directly
from Nikola Tesla.  He was bidding on the coil so he wouldn't have to wind
the forms he has.

I examined the materials of this coil carefully and they do fit in with
early 1900 construction.  I first thought the plywood construction indicated
that it was from the 40s or 50s.  Then I found out that plywood was invented
over 1000 years ago by the Chinese.  From my experience in dealing with
antiques, I could tell the patina on the copper primary was genuine (I had
to replace it with new copper because it was kinked in several places - but
I still have the original).  The cotton covered secondary wire was Tesla's
secondary wire of choice for small coils.  The patina on the end screws and
plywood are also genuine.

Because this coil was obtained from the estate of an FBI agent, I have
wondered whether the FBI agents divvied up some of Tesla's personal effects
after they searched his room?  That, in itself, would be an interesting
revelation.

Oh, yes.  The guy I was bidding against told me the coil is supposed to have
antigravity properties.  If it does, they are minute.  I put the coil on a
regular household foot scale while running it.  The scale did change
slightly when I started the coil, but the change was so slight I chalked it
up to electromagnetic force.  The scale I used was made entirely of a
ferrous metal.

Dave

 > -----Original Message-----
 > From: Tesla list [mailto:tesla-at-pupman-dot-com]
 > Sent: Friday, April 02, 2004 3:36 AM
 > To: tesla-at-pupman-dot-com
 > Subject: New bipolar
 >
 >
 > Original poster: "John Richardson" <jprich-at-up-dot-net>
 >
 > Hi,
 >
 > Just would like to run this past anyone who has built a bipolar, and see
 > what they think.  I've never built one, and am open to advice.  Killing
 > time until I can run the big TC outside!
 >
 > Lately I've been into building small TCs, and would like to keep the guts
 > for this one in an 8" by 12" enclosure, with the only external item,
 > excluding primary and secondary, being the gap.
 >
 > Secondary:  12 inches of #32 heavy build.
 > Primary:  1/8" soft Cu tubing, turns to be determined with scrap
 > wire after
 > assembled before made permanent.
 > Cap:  MMC array, out of .15 CD 942s, close as I can get to .0133.
 > Trans:  The smallest and cutest little 9/30 on the planet.
 > Gap:  3 or 4 gap tungsten.
 >
 > Even though the trans is small, space in my chosen enclosure size will
 > still be limited, so I plan to run the MMC bank in an equidrive
 > arrangement.  Are there any inherent disadvantages to this?  And, after I
 > determine the number of capacitors required, and if that amount is odd
 > instead of even, can there be an even number on one side and an
 > odd number
 > on the other?  I wouldn't think this would matter, but I've learned to
 > expect the unexpected with these things.
 >
 > Lastly, there seems to be limited sites with bipolars, so if anyone has a
 > link, I would appreciate it.
 >
 > Thanks as usual,
 >
 > John Richardson