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budget caps (I did a quick test today)

Original poster: Mike <megavolts61@xxxxxxxxx>

Original poster: "Jim Mora" <jmora@xxxxxxxxxxx>

Hi all,
I did a lil experiment today. I know a lot of beginners use beer bottle caps and a couple weeks ago I was talking about using polyethylene containers instead. I took an empty poly container that previously held Lysol antibacterial wipes. It just seemed like a good one for this test. Not terribly thick walled, but a nice cylinder. I measured the dimensins after wrapping it fairly neatly with foil...I extended the foil underneath and flattened it as best I could. I then roll an inch wide copper strip (30g) around a plastid rod to give it basically a pipe shape... and then affixed it using the lid of container and connected my DMM to it in cap mode. I then began filling it in increments of 40 mL (using a measure cup...had 40 mL graduations...so I used it haha). I plotted the capacitance vs volume and it came out very linear, probably over .99 correlation. The max came out to 1.175jF, so it would not take too terribly many of these to make a nice salt water cap bank. And doing reverse calculation(being I was pretty confident about the measured capacitance), I determined the thickness of the dielectric to be about 35 mils.. Now depending on who you ask, that could make some good high voltage standoff. Conservatively it would take 15kVDC, but I saw another reference that said HDPE has a dielectric strength of 5000V/mil...I think that could be a typo....but the range from the first table said it could go up to 1200v/mil which means this could go as high as 40kVDC. I will destructively test this tomorrow, if possible. I got interrupted today, so I only got the measurments done. One purpose of this 'experiment' is to come up with a cheap alternative to MMC arrays. I don't know what they run, but this cap only cost probably 50 cents to make and could aid in tuning simply by adjusting the water level in the caps. 
Mike


Hi,

Does anyone have a Maxwell 37677 that hasn't been over-volted that they
want
to sell? I need a third one as the base of a fullwave voltage doubler
to be
powered by a 15kv/120 NST pair and variac. The next 2 stages are 4000pf
big
door knobs (this should add some punch to the current output).

Thanks,
Jim Mora
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