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

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---------- Forwarded message ----------
Date: Sat, 23 Jun 2007 21:31:50 -0700
From: Barton B. Anderson <bartb@xxxxxxxxxxxxxxxx>
To: Tesla list <tesla@xxxxxxxxxx>
Subject: Re: A photographic tutorial of Pancake Coil winding...with
    movies...(fwd)

Hi Jeff,

You wrote:

>As for the cylinder acting like a coil, that's interesting.  I did remove 
>the cylinder just now and took more operation photos and the coil worked 
>better.  Perhaps it is just that your theory doesn't match the resonance of 
>the coil according to the cap size I am using.  I wonder if replacing the 
>tube back again and changing the capacitor value would make a marked 
>difference in the discharge?  Any suggestions are more than welcome, in fact 
>I can photograph the Pancake with all 128 combinations of the condenser if 
>you guys want!  That would be fun.
>  
>
If the coil works better without the cylinder, it's possibly due to the 
coil breaking out at a higher charge as compared to a the pipe edge or 
due to the pipes loading taking out of resonance. I'd love to model it, 
not possible for me since this particular multilayer 9" coil has a very 
unique winding style. You might try a 1" brass ball on top of the pipe 
to stop that particular breakout and see how it reacts. I notice the 
small 1/2" pipe diameter is producing early breakout along it's length 
(the coil would really like a larger radius of curvature). That would of 
course load the coil further and you would need to change the primary 
cap value to match.

Looking at the 2 turn primary with the 0.024uF, should be operating at 
about 610kHz with the pipe and secondary in place. The pipe itself is 
loading the coil anywhere from 20Khz to 70 kHz. I can't be exact here 
(you could measure Fr with and without the tube to find out). Increasing 
the primary capacitance would drop the primary frequency to match the 
tubes effect. A capacitance of 0.032uF would match the larger frequency 
shift, so somewhere between 0.024uF and 0.032uF.

Take care,
Bart