Re: 16" Pancake Coil discharge photos

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "Jeff Behary" <jeff_behary@xxxxxxxxxxx>

Bart,

The largest flat spiral coils I've made were 24" and 48" diameters - 
very different though!
The 24" coil used 1mm thick x 25mm PVC "edgebanding" for insulation 
between the turns.  It used 30 AWG wire.  I tested it at 7500V .032 
mfd with a 5-series tungsten spark gap for approx. 4 seconds - I got 
an amazing 24"+ spark from the top when the whole coil died instantly 
from an internal short due to the PVC interleaves not giving a 
sufficient insulation.  It was fun while it lasted.
The 48" coil was originally a primary coil for a 10.75" OD 3 foot 
tall secondary coil.  (Odd size, but worked well!).  The coil was 48" 
OD 12" ID with around 25 turns of solid 10 AWG wire.  For the flat 
experiment I used the outer turn as the primary and the inner turns 
as the secondary.  I was getting powerful 4" sparks from a simple 
15kV 30mA neon and a two-quart leyden jar.  This was years before I 
started making Pancakes...
I also have two 18" diameter coils with 1" IDs wound with 10 AWG 
parallel stranded wire, asbestos coating (?or something 
similar?).  These were more for demonstrating inductive 
effects...there is a frenchman W. H. Guilleminot that did a lot of 
research in flat coils.  He wrote a few books in the 20s.
I have one translation that I have to scan for the site...

I have another 18" diameter flat coil wound with 21 AWG wire.  It 
gives 8" arcs, but works better as a P:S for my Pancake magnifier 
system.  One day I attached a wire leading to a 5" diameter x 24" 
tall helix coil (close wound 24 AWG) and saw 4 foot arcs from the top 
to the ceiling of our spare bedroom!  That was a surprise.
http://www.electrotherapymuseum.com/2006/18inPancake/index.htm
http://www.electrotherapymuseum.com/Forgotten_Tesla_Technologies/Magnifier_Pancake_System/index.htm

Tonight I finished a replacement coil for the floor model demo unit - 
it is about 14" in diameter, and this time cast it into a glass lamp 
shade so that I could see all of the windings were permeated 
completely.  I used a mixture of linseed oil and beeswax that 
hardened to a consistency of peanut butter.
In initial testing I was getting nice crackling 6" sparks and no 
signs of breakdown whatsoever.
For more on Pancake Coils in general, check out these pages:
http://www.electrotherapymuseum.com/2006/PancakeCoils.htm

There is a lot of general information, but I haven't updated it with 
coils made in the last months...
Jeff Behary, c/o
The Turn Of The Century Electrotherapy Museum
http://www.electrotherapymuseum.com

_