RE: A photographic tutorial of Pancake Coil winding...with movies...(fwd)

["Tesla list" <tesla@xxxxxxxxxx>]

---------- Forwarded message ----------
Date: Thu, 21 Jun 2007 22:01:17 -0500
From: David Thomson <dwt@xxxxxxxxxxxx>
To: 'Tesla list' <tesla@xxxxxxxxxx>
Subject: RE: A photographic tutorial of Pancake Coil winding...with
    movies...(fwd)

Hi Jeff,

> I'm not sure which coil you are referring to.  The coil shown at:
> http://www.electrotherapymuseum.com/2007/9inPancake/index.htm
> is a flat spiral secondary, 300 turns of 26 AWG, and a 2 1/2 
> turn primary of 3/4" tall flat ribbon.
> Its a Pancake 100%.  The discharger was made as a tube, 

The discharger tube is acting like a third coil.  Bart and I just figured
this out.  I built a similar coil:
http://www.tesla-coil-builder.com/FlatSpiralSolenoidCombo.htm

When Bart worked out the math he found the tall solenoid coil in my design
works just like the brass tube in your design.  

> To give you an example, the Campbell Electric X-Ray machines 
> (first built in 1901) used a Pancake Coil seen here:
> Machine:
> http://www.electrotherapymuseum.com/2006/CampbellE/index.htm

I noticed that these coils also have a tall cylinder in the center.  I also
notice that the discharge in this picture is approaching the standing wave
discharge configuration in mine, although it also has strong streamer
characteristics still:
http://www.electrotherapymuseum.com/2006/CampbellE/images/Effluve1.jpg

> The unpotted coil is from a near identical model that needs 
> restoration.  I am going to photograph a cross section of 
> this coil that we made (waterjet cut), it was actually burned 
> out.  

I really appreciate the work you have done here.  Between you and Bart, I
have learned more about the combination coil setup in two days than I did
when I built it nearly five years ago.  We can do a lot with this and it
opens the doors wide for magnifier design and control.  You can actually
make your brass pipe resonate at an octave or harmonic of the flat spiral
and get real magnifier action.  This magnifier action, if properly designed,
can also be used in wireless power transmission experiments.

> The coil I am constructing as a demo will produce a very 
> similar spark a few inches longer than the Campbell but it 
> will be a flat spiral instead of multi-layered to keep it 
> simple..  It'll have 1/3 of the wire but will need a bit more 
> current too.

Make your brass pipe such that you can adjust the height when you are done.
You will find you can tune the coil this way.

> Most of the early machines and books in the 
> US referred to Pancake coils as "Tesla 
> Coils", and cylindrical coils as "Oudin Resonators".    

What I'm saying is that the addition of the brass tube connected to the
center of the flat spiral makes the coil a magnifier.  The brass tube, as
Bart just pointed out, acts just like a third coil.  

As I see it, this is possible because the vibrations in the brass tube (or
wound solenoid) are longitudinal in nature.  Only longitudinal waves could
see a wound coil and solid metal tube as the same thing.  The longitudinal
waves occur because the flat spiral center tap is acting like a reed in a
musical instrument and the tall solenoid is acting like a Helmholtz
resonator.  Instead of air molecules being vibrated, electrons and or
photons are oscillating in place along the tube.  There is no current
flowing through the tall solenoid.

Well, actually there is current in your version as indicated by the
streamers.  But in my version, the current has been completely eliminated
and only a corona standing wave appears on the top load.  The corona
standing waves are further evidence of longitudinal waves in the tall
solenoid.

Dave