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My caps seem to be a reliable explosive ;-)




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From:  Scott Cutler [SMTP:spcutler-at-ucdavis.edu]
Sent:  Monday, February 23, 1998 9:31 PM
To:  tesla-at-pupman-dot-com
Subject:  My caps seem to be a reliable explosive ;-)

Ok, well I haven't finished my caps yet, so I don't know for SURE that
they'll work, but the calculations seem sound and there's no reason that
they shouldn't work.  My original estimate was somewhat wrong; you
actually need about 10 boxes of bags.  
Here's the parts list:  
145 gallon size freezer bags (they must be freezer bags; the other types
are too thin.  Make sure that they're at least 2.5 mil thick, pref. 3
mil)

aluminum foil

tupperware container (I haven't figured out the ideal size for this yet,
but I think one that's close to half the size of a bag and a few inches
high should do the trick)

misc wire, bolts, nuts, washers etc.

First, if the bags have a white writable surface on them, remove this with
nail polish remover.  I don't know if this is absolutely necessary, but
why risk it?  Actually, it may be worth the risk; this part will take
several hours.  Then soak the bags in water to remove any acetone residue. 
Dry them thoroughly.  Then, cut off the ziplock tops to form approximately
a 27 x 27 cm square.  Then, cut this in half to form two 13.5 x 27 cm
rectangles.  Now, divide your bags into 5 piles of 58 half-bags.  For
each pile, cut 20 pieces of aluminum foil, about 12 x 25 cm but with a 4
cm (or so) wide tab coming from the middle of the long side.  Now, find 20
"non-loop" (that is, with a solid bottom)  half-bags and center the
aluminum foil rectangles in them.  Now, stack the bags like this:  
tab to left 
empty bag 
empty bag 
tab to right 
empty bag 
empty bag 
tab to left 
...and so on 
And of course, do this for each of the 5 piles.  Now, use small
bolts and some washers to connect the foil tabs on each side, connect the
five bags in series, alternating (you may want to stick a few extra bags
between the individual piles), connect the ends with heavy wire, and stick
the whole mess in the tupperware container.  Fill the thing with oil
(mineral is best, although motor will probably do), attach the lid (with
holes for the wires to come through), and let the thing sit at an angle
for a few days so the bubbles rise out.  You may want to put this in a pan
to catch any oil leaks.  
This is the first capacitor I've planned other than the failed bottle
caps.  It should provide ABOUT 5.4 nF of capacitance at 15 kv.  This is
good for a 15 kv, 30 mA NST.  It's pretty much my own design, but I got
the idea of using plastic bags from a posting on Bill Beatty's website.
Comments from experienced coilers would be most welcome, as I am as much a
beginner as the original poster. 
Thanks! 

Scott Cutler