new cap idea

["Metlicka Marc" <mystuffs-at-orwell-dot-net> (by way of Terry Fritz <twftesla-at-uswest-dot-net>)]

a couple days ago i was siting at my desk reading the posts on the list
when i glanced into the kitchen, there sitting on my hoosier cabinet was
a stack of those cheap "party cups." IDEA" i thought now there's a cheap
easy to make capacitor.
i grabbed the stack 25 and started wrapping aluminum foil onto each cup
with a tab sticking out of each, about 3" i stacked them back together,
alternating the tabs side to side. connected the tabs on each side
respectively and took a dry reading.
.081nf. now i didn't take great care in the wrapping, and broke one cup
cramming them together but IT WORKED.
now i know that mmc's are becoming the norm. but this is a cheap easy
cap to make.
i charged the cap to 490v dc, dry. it held the charge for two hours
until i couldn't resist discharging it. i'm going to do a little
refinement and calculating, then some experiment a tad more, but i think
with some dielectric thickness checking and some better conductor
coating.
maybe some two cup cross section distance measurements and some mineral
oil immersion. this could be a good low budget, quickie capacitor that
could be made to any wanted value. i'm going to start looking to see if
these come in polyeth. or polypro., the ones i used were styrene i
think, at least they smell like styrene when burned a bit.
the fact that the cups wont hold to many air bubbles they should be very
durable caps.
i'll keep ya posted..........marc