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

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---------- Forwarded message ----------
Date: Fri, 22 Jun 2007 01:13:04 +0000
From: Jeff Behary <jeff_behary@xxxxxxxxxxx>
To: tesla@xxxxxxxxxx
Subject: Re: A photographic tutorial of Pancake Coil winding...with movies...
    (fwd) -- binary capacitor (fwd)

Marko,

The dielectric used was overhead transparency sheets.  I 've used both 5x7 
aluminum flashing sheets and aluminum foil cut to 6.5 x 9 (to leave a 1" 
border).  I have a multimeter from Harbor Freight ($35) that measures 
capacity.  With 2 - 4 sheets of acetate you can get around .001 mfd
per "cap".  The box contains a stacked cap (if I remember it was around 1" 
thick) tapped for the values  of .001, .002, .004, .008, .016, .032, .064.  
The total value is .127 mfd.  The cap can withstand a full 4kV at 600mA with 
no problems to date.  (I made it 2 years ago and use it daily)

The values remain pretty true providing all of the cap is tensioned the same 
way.  I sandwich the whole thing between steel plates when finished and 
tension the plates until the values of the cap measure their intended 
values.  The difference between loosly assembled sheets and compressed 
sheets can be a difference of double or more.  I then toss the whole thing 
in wax or oil to fill the edges of the sheets where the foils do not extend 
to prevent corona losses.  It helps to round the edge of the foils/etc. as 
in making any cap.

Both coil testers are insulated with paraffin wax.  The smaller "kicking 
coil" arrangement uses waxed paper for a dielectric and tin foil sheets.  It 
was made from an old broken high voltage cap that was disassembled and the 
parts salvaged.  This unit has an additional .128 mfd cap  making the total 
from .001 - .255 mfd.

Also, its good to note that regardless of the values of a single condenser - 
the concept works for making any cap as adjustable as it possibly can be.  
Even if the values of the plates are .0017 mfd, you can adjust it from 
.0017, .0034, .0051, etc. in .0017 mfd increments.  So you can take an 
existing stacked plate cap and make it more useful just by tapping it at the 
binary "plate number" equivalents.  In either case you get the most 
adjustability possible...

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

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