Homemade Capacitors

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Original poster: Drbillpmt@xxxxxxx 

Hi All,

I've been following the capacitor emails for some time. Maybe my 
capacitor making method will be of some help.

First:  I use polypropylene as a dialectric. The source for it is the 
film used to tint vehicle windows. Not all of it is polypropylene, 
but much of it is. Some of it is as thick as .025 or even more. At 
650 VDC per Mil, .024 would give you 15,600 VDC.

Second: I use brass shim stock for the metal. It is .005 thick and 
rolls quite easily. It is 2-Inches wide. Using 4-Inch strips of the 
poly, I leave one inch on both sides of the metal. For connections, I 
turn the shim stock 90 degrees and flatten it so I have a 2 inch 
strip coming out of each end of the roll. It is not easy to roll but 
it can be done.

Third: After the cap is rolled, I place tie-wraps around the assembly 
to hold it together. My first try was for a cap that needed to be 
around 0.004 UF for a 5 KVRMS output transformer with the spark gap 
across the transformer secondary. The capacitor went from one end of 
the spark gap, through a 20 Ohm non-inductive 75 Watt resistor to a 
spiral coil center. From the end of the spiral, I connected to the 
other side of the spark gap.

This setup now has over 20 hours on it with no problems. The cap 
stays cool. And the cap is dry - NO OIL!

I see no reson why one could not make a higher capacitance unit, for 
a higher voltage the same way, just scaled up.

Dr. Bill