Re: Build own capacators

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "david baehr" <dfb25@xxxxxxxxxxx>


What is the Voltage when  corona first appears ? (in air ), if  a 
person wanted to make a 'dry' cap ,..  maybe 900-1000 volts ????  My 
rolled caps got alot of use the first year or two after I made 'em, 
then sat around alot after that.  I did have a couple of failures 
,.....#1  experimenting with a SYNC rotary, ....#2 , I was dorkin 
around with a small coil with a 12/30 neon. Not sure about that one, 
before that, I ran them caps daily for weeks at 5kw with my 8" coil 
in da basement , with a rotary,....repair was 'FAIRLY' easy both 
times,  the burn through was only about 3-4 turns in from the out 
side,....I just unrolled , place a poly patch over da hole, and 
re-rolled, kinda messy, but the cap was up and running within an hour 
or so.........Yes, Im a bit antiquated  ,....;-) ,.......I still play 
( Records/LP's ) too ,... , but, I used glass plate caps in air(nice 
glow ) on my first few coils, .rolled poly was a big improvement for me

From:  "Tesla list" <tesla@xxxxxxxxxx>
To:  tesla@xxxxxxxxxx
Subject:  Re: Build own capacators
Date:  Fri, 16 Dec 2005 17:20:29 -0700
>Original poster: Terry Fritz <vardin@xxxxxxxxxxxxxxxxxxxxxxx>
>
>Hi,
>
>At 07:03 PM 12/15/2005, you wrote:
>>I will publically applogize for hurting the feelings
>>of good ol' Matt.  My point is this (and lets end it
>>here): if you want your coil(s) to last FOREVER,
>>Forget about homemade capacitors.  Any new comer that
>>has the desire for a Quality coil should build an MMC!
>>SIMPLE AS THAT...
>
>MMC really don't last "forever".  See:
>
>http://hot-streamer.com/temp/CD942C20P15K-MMC-Capacitor-Lifetest.pdf
>
>Because we run them at 2000VAC when they should only be run at
>630VAC, the plates inside get eaten by ionization and burn up in say
>75 - 100 hours.
>
>One could use many more caps and run each at ~600VAC to get to say
>100,000 hours, but then the cost goes way up.
>
>Most of use are perfectly happy with a say 75 hour life, if you need
>to run longer, then the normal MMC should be changed or another type
>of caps used.
>
>Homemade caps have a similar ionization problem due to their single
>poly layer.  Even in oil, there is significant ionization damage
>when we are talking many hours of use.  Homemade caps are each too
>unique to say much about how long they will last.  Dave's have been
>going about 11+ years, but I am not sure how much actual run time
>that is.
>
>Commercial caps (but NOT "pulsed" type caps) will actually be made
>with a number of "cells" in series to over come this in their oil
>filled caps.  That's why they can get $500 - $1000 for them.  I
>think DC Cox recently mentioned his fully rated AC Tesla coil duty
>caps (the kind that will last "forever") ran $1000 each in QTY of
>ten!!  So his ten caps probably cost more than ALL of our MMCs
>combined!!
>
>Cheers,
>
>         Terry
>
>
>