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
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