Re: Caps Secondary Chokes


The materials and construction techniques are as follows (from memory and 
having seen part of the TCBOR video):  

Materials: 16' Aluminum roofing flashing (sold in hardware stores, 
			about 12" wide)
	   16'6" 60mil (~1/16") polyethylene (I used polypropylene because
		I couldn't find the polyethylene)
	    6" PVC pipe 
	    2  end caps for pipe
	    2 round head bolts and nuts
	    heavy wire
	    clean rubber gloves
	    acetone or denatured alcohol
	    transformer oil
	    large size nylon zip ties

This capacitor MUST be oil filled!
The plastic sheeting should be about 1.5" wider than the aluminum sheet.
The aluminum and plastic sheets should be cut into two equal lengths (8' and
8' 3" respectively)
The PVC pipe is the container for the cap, so it must be longer than the 
strips are wide.
Don't use rubbing alcohol as it sometimes contains glycerin.
Use a helper
Cleanliness is next to Godliness :-)

Glue one of the end caps onto the PVC pipe.
Use tin snips to round the corners of the aluminum sheeting.  Drill
a hole in the middle of the end of each aluminum strip.  This hole is
for the bolt and is used to attach the heavy wire to the aluminum strips
Lay out clean papers in a strip about 8" long on a clean table.  Lay out
the strips of plastic and strips of aluminum.  Put on the clean rubber 
gloves (finger prints can cause leakage) and use the solvent to clean both
sides of all four strips of material and the inside of the PVC pipe.  Attach
the wires to each strip and stack the four strips in the following manner:


= plastic
+ aluminum

Then, with the help of your (gloved) assistant, roll up the sandwich into 
a roll small enough to fit into the pipe.  This takes a fair amount of effort
because of the springiness of the materials.  When the roll is made, use the 
nylon zip ties to keep the thing rolled up.  Next, place the roll into the 
pipe.  At this point, you should have a pipe with a rolled up sandwich in it
and the two wires sticking out.  You may wish to use a sealed smaller pipe 
in the center to reduce the volume of oil in the cap.  Next is figuring out
how to seal the top.  At this point, I didn't see how it was done, so I can't
offer much advice.  (Some professors would say at this point 
"student proof" :-)).  Before you seal the top though, you must fill the thing
with oil.  You can get transformer oil from some oil companies in larger
cities.  I got mine from Siegel Oil in Denver (303)893-3211.  The guy that
built a capacitor using this technique used the carburetor on his car to
provide vacuum to suck out the air.  You may be able to get the air out by
just letting the cap sit for a while after you put in the oil.  

I saw a capacitor produced using this technique and I think it is much
better than my original design which uses aluminum foil and stacked plastic