Re: 16" Pancake Coil discharge photos (fwd)

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Moderated and approved by: Gerry Reynolds <greynolds@xxxxxxxxxx>



---------- Forwarded message ----------
Date: Fri, 22 Dec 2006 20:26:29 -0800
From: Barton B. Anderson <bartb@xxxxxxxxxxxxxxxx>
To: Tesla list <tesla@xxxxxxxxxx>
Subject: Re: 16" Pancake Coil discharge photos

Hi Jeff,

Thanks for the flat coil links. I've seen these before and they 
certainly were part of my wanting to build flat coils and to put a 
little Bart flavor in there, not necessarily in the aesthetics, but the 
possibilities. I've built a flat coil already using a single MOT driver 
and single static gap for some interesting but not dramatic sparks. I 
want to start building a coil of high coupling and yet simple non-maggy 
setup. I think the flat coil has that possibility simply due to it's 
geometry where any other configuration does not. That is part of my 
curiosity. The rest is simply curiosity.

I realize and have experienced the issues with flat coils regarding 
flashovers, using flat coils with a helical center coil, and that basic 
geometry. I'm now going back to the beginning. Looking at the Tesla's 
design, building something replicating that design, and then measuring 
the coils misc. attributes. Following that and possibly the data it 
provides, I can account "first round" for a highly coupled tuned primary 
circuit to drive it. I'll likely start with a simple spark gap and then 
upgrade the coil to a solid state driver.

Take care,
Bart

Tesla list wrote:

> 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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