Re: Large Diameter Pancake Coil Discharges (fwd)

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Original poster: William Beaty <billb@xxxxxxxxxx>


Below is a message from Jeff Behary which I received off-list.  Jeff gives
permission to forward it here.


billb wrote:
>   QUESTION:  If we actually build a large pancake-style TC secondary,
>  and mount a sphere terminal on the end of a central rod, then does the
>   discharge tend to occupy a fairly narrow cone which is directed
>   outwards from the pancake coil?      Yes or no.
>
> If nobody has experimentally determined the answer by building and
> operating such a pancake-shaped secondary, then we have no business
> pretending that we know the answer.



From: Jeff Behary <jeff_behary@>


Hi Bill,

I saw your question on Pupman regarding the Pancake Coil drawing in
operation...   Please look at some Pancake Coil discharges here:

http://www.electrotherapymuseum.com/WhatsNew.htm

Sorry its a mess, but I have to reorganise it a bit.  I disagree with the
criticisms of the drawing 
shown.  [http://homepage.ntlworld.com/forgottenfutures/tesla/tesla_4.gif]
I've built up to a 24" diameter Pancake Coil that gave over 3 foot hot
discharges. It was mounted horizontally and gave a cone-like corona...
unfortunately I pushed it too far (burned it out, the coil was embedded in
1.5" thick PVC interleaves) and didn't get a change to photo it in
operation.I have just built a 16" diameter version and will photograph it
this weekend in operation.

The discharges branch outward, and all Pancake Coils give tremendous
discharges when built properly.  At around a kilowatt a table top Pancake
Coil (a 9" Diameter bipolar coil works well) will produce purple-orange
arcing discharges a foot long and hot enough to melt 24 gauge wire, the
heat being felt several feet away.  Horizonally they tend to also spark
directly outward in a similar cone...only bowing upward if an arc is
formed to something...

At our museum we have something special regarding Tesla Pancake Coils:
The earliest surviving Tesla Coils built by Pancake Coil and X-Ray Pioneer
Thomas Burton Kinraide in 1896. Kinraide made over 500 glass plate
negatives of Lichtenberg Figures using Pancake Tesla Coils. This
collection is preserved at our museum and represents something extremely
rare - many of the phenonemon described by Tesla in his lectures in full
scale 1:1 photographic "proof" as it were.

On this topic it is interesting that very few people ask questions and
everyone assumes answers not actually having witnessed these coils.I have
built 3" Pancake Coils that gave 6" sparks at 100 watts power @
110V.Tesla's efficiencies were quite amazing.I have one early unit similar
coil to what he was building - its a bipolar pancake coil with less than
1000 volts in the primary transformer and a .6 MFD (!!!) mica capacitor.It
will produce over a 10" flame (fire) between the terminals and will even
give a 6" spark if you touch the plug against a 9V battery a few times
rapidly (bored silly during hurricane season without electricity)

People also jump to conclusions sometimes because they've never witnessed
some of these discharges in person...A typical Pancake Coil can produce a
spark discharge equal to its diameter, and an arc discharge equal to its
radius.  (Arc meaning with heat felt several feet away).  When operated
correctly, the P:S turns ratio may be as small as 4:1 or less as stated in
Tesla lectures.

A large Pancake Coil or flat spiral can also produce "Phantom Streamers"
many times longer than the actual sparking discharge of the coil.  These
streamers are seemingly uneffected by the outside surroundings, such as
people or walls or conductors.  They appear as wavy white whisps of
electricity strobing in all directions.They are unlike sparks and also
unlike effluves or corona effects seen with most normal Tesla Coils.
Kinraide was able to produce such discharges over 1" thick and 30" long
with a large table top Pancake Coil.I've personally witnessed these
streamers over a foot long and 1/2" in diameter.  For me they are the most
fascinating display of electricity I've ever witnessed (I've operated over
200 antique Tesla Coils).

So the real question may be what electrical phenomenon did the artist
witness in order to sketch the pictures shown!  I encourage everyone to
visit my site and browse through the Kinraide archive to see some of these
discharges.  Better still, build a Pancake Coil and see for yourself!
They have forever changed my view of Tesla and his lectures.  The vivid
and exquisite imagery and descriptions Tesla uses seems eccentric to most,
but after witnessing some of these phenomenon in person one will see that
Tesla wasn't exhaggerating even in the least!  They will inspire a
curiosity that is hard to stop - I've been building Pancake Coils and
studying them for nearly a decade now and each coil brings something new
and exciting.

http://www.electrotherapymuseum.com/KPlates.htm

My wife Rita and I discoverd these in Kinraide's laboratory, which was
left untouched for over a century.  Kinraide built the first portable
commercial Tesla Coil, and it was reported decades later (after the market
had already been flooded with 100s of Tesla Coils for various medical,
X-Ray, and quackery uses) that the Kinraide Coil was the most efficient
apparatus ever designed (next to those Tesla himself made).

Tesla made 50 types of Pancake Coils to form the basis of his lectures and
circuit controller patents.I've made 3D CADs of many of these which are
also on the site and in the presentation. They are really interesting, and
I've outlined a lot of the discharges in a power-point presentation seen
here as a PDF:

http://www.electrotherapymuseum.com/LongIsland/LongIsland06.pdf

There are actually 30 movies in the original presentation just made this
October 6-8 in NY...all of Pancake Coils in operation and the strange
effects produced.  I can send you a CD if you are interested.All of the
images in the PDF with red-outlined boxes are movies.

Best regards,

Jeff Behary, c/o
The Turn Of The Century Electrotherapy Museum
http://www.electrotherapymuseum.com