RE: REAL CAPACITOR (where can i buy one?)

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Ross Overstreet by way of Terry Fritz <twftesla-at-uswest-dot-net>" <ross-o-at-mindspring-dot-com>

You need to very cautious about listening to your "reliable source" who says
that MMCs "suck" when compared to professional capacitors.  Most
professional caps are metal foil construction with some low loss dielectric
sandwiched in between.  They are typically composed of many rolls of this
material in a plastic or steel can.  One flash-over between the plates of
metal foil and the capacitor is history.  Metallized film MMC caps are
self-healing and can withstand considerable abuse.  The manufacturing
technology of most MMC caps  is far beyond that of some of the metal foil
caps.  Furthermore, if you get into trouble you can usually replace
individual MMC caps instead of buying a new professional capacitor.  You'll
find that most Maxwell or Hypotronic caps will run in the $350 to $650 range
new.  You can find them for $125-$200 on Ebay but that is a BIG gamble
because these things do have a finite life span and most are salvaged from
medical laser use after so many hundreds of hours of use.

There is an economic limit where you can buy larger capacitors cheaper than
you can build MMCs but you are far from this point at the moment.  There is
a lot of info in the archives on MMCs.  You should do a little research on
this issue (and then confront your "source").

Be careful,
Ross-O
http://users.better-dot-org/roverstreet/


-----Original Message-----
From: Tesla list [mailto:tesla-at-pupman-dot-com]
Sent: Monday, April 09, 2001 5:42 PM
To: tesla-at-pupman-dot-com
Subject: REAL CAPACITOR (where can i buy one?)


Original poster: "Drew Murray by way of Terry Fritz <twftesla-at-uswest-dot-net>"
<drewallmighty-at-hotmail-dot-com>

Hello Everybody,
Yes, it's me ....DREW!
I'm Back and i am aiming to get my coil working better than ever. You may
remember some of my earlier posts from before the science fair such as:
DArN CAPACITORS
My PT is loud!
and so on.
I won second place and $80 (measly i know) in the physics category at the
new brunswick provincial science fair that was held at the university of
moncton.
I am now using my coil to put on shows during intermission at school plays
and variety shows. It has gained me a lot of popularity. (HE HE)
I am 15 years old and i am making nearly 4 foot long sparks with my ,so
called masterpiece of a tesla coil! People call me a genius and stuff.
I am rather tired of frigging around with square sheets of plastic and al
foil for my capacitor. It worked pretty good for an uncalculated capacitor.
Vapor barrier melts! 1 gallon zip lock bags do not melt, this makes them
much better for dry capacitors. I wonder why this is. Anyway, i better get
to the point. I have the school's permission to buy a capacitor with pretty
much an unlimited budget. I have lots of cash and i want a capacitor that
will make my tesla coil kick!
I want a professional Polypropylene pulse discharge capacitor, so where do i
buy one? I am in New Brunswick, Canada, so i want it from a company that is
somewhere on this side of the planet! I am not really interested in MMC's
because i have heard from a reliable source that they suck, performance
wise, compared to professional pulse caps.
I have a 1kva 120:4200 PT and i am feeding 300v into it. I am using a 20 ohm
4.5 amp max rheostat and a burned out 250va 10000v oil burner igniter in a
series with the pt for current limiting. I have no idea what is coming out
of the PT, except that it is somewhere around 10500v. I have been running it
this way for a few months now and it never gets warm. Is there some way that
i can calculate just what is coming out of it so i can determine what size
of capacitor i will need.
Any help, advice and/or comments would be greatly appreciated!
                                                            Sincerely,
                                                            Drew Murray

Notes:  Always build a plate capacitor with a little higher capacitance than
required if you are going to have it in mineral oil. The plastic will swell
and lower the capacitance drastically, causing performance to lax.
_________________________________________________________________________
Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail-dot-com.