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Mylar Caps!




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From:  Zuma [SMTP:mwise-at-ns.sosis-dot-com]
Sent:  Saturday, February 21, 1998 9:57 PM
To:  tesla-at-pupman-dot-com
Subject:  Mylar Caps!

Just out of curiosity is there anyone who has used mylar caps out there
anywhere? I am aware of its high losses but I got to thinking if it was
worst than glass in that area. I recently went digging around the house
and found to empty PineSol bottles, out of curiosity I wanted to see how
much capacitance these would be able to produce. The bottles are mylar
according to the Recycling Code on the bottom(5 PETE). These are the
48oz. size bottles. Any way I filled one with salt water and placed it
in a bucket of salt water. When I measured the capacitance I was
suprised that it came up as .005uf. I have not tested the caps on my
coil yet but I am hoping for better results than with my regular
saltwater/aluminum tape bottle caps. I am not sure of the mylars
thickness since I only have two I didn't want to destroy one just to
find out. But I am fairly certain they will hold up on my coil becuse of
its high breakdown voltage and the fact that I am only running a 7.5kv
neon on my coil.

If these caps prove to be better than glass caps I will use these until
I get around to making some poly caps. I need to get hold of two more
bottles giving me a total of 4 bottles with a .02uf. I currently have 
two bottles that are measured at .01uf.

These caps are extremely easy to make. If they increase my output on my
coil I will be very happy. My coil is a 6.25"x19" wound with 22awg
magnet wire, using a series spark gap and a 13 turn primary wound with
#8 bare solid copper wire. My maximum spark from this coil, running
.015uf s/w caps with a 7.5kv-at-60ma neon, was about 13"-15".