Re: MMC or Maxwell? Which is better?

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

Original poster: Crow Leader <tesla-at-lists.symmetric-dot-net> 

On Sat, 28 Feb 2004, Tesla list wrote:

 > Original poster: Mark Broker <mbroker-at-thegeekgroup-dot-org>
 >
 > Ken,
 >
 > I understand your disdain for under-rating components, but I don't
 > understand your disdain for MMCs in general....

I prefer integrated circuits over rooms full of wirewrapped transitors. I
also prefer less than dozens of parts and connections to fail. That's just
me though.



 > Not that you'll change your mind, but some rebuttal below.
 >
 > On Fri, 27 Feb 2004 16:11:01 -0700, Tesla list <tesla-at-pupman-dot-com> wrote:
 >
 > >Original poster: "Crow Leader" <tesla-at-lists.symmetric-dot-net> Here is my main
 > >point.
 >
 > <snip>
 >
 > >  > One other thing about MMCs ;-))  They were designed from the ground 
up for
 > >  > "Tesla coils".  So all the fudge factors and over design was directed
 > >  > toward the common mistakes and mishaps "coilers" make.
 > >
 > >Wrong. I don't see "designed for tesla coil use" in the cornell dublier
 > >catalog anywhere.
 >
 > I believe Terry means the MMC, not the CDE capacitors.  I don't believe
 > you'll find "designed for Tesla Coil use" in most capacitor catalogs
 > anymore, either.  In fact, I think the only manufacturer that makes "Tesla
 > Coil Capacitors" is Plastics Capacitors.
 >
 >
 > >  > Another thing "I" always stress is that MMC have (should have) drain
 > >  > resistors which I think vasty increases safety...  No worries about
 > >  > residual charges on an MMC...
 > >
 > >I recall they catch on fire alot, burning people's circuit boards. It 
shifts
 > >the problems elsewhere.
 >
 > I recall two instances in which people placed resistors against (or near
 > enough) the capacitor body causing problems.  I also recall at least two
 > instances in which a Maxwell, Arctronics, Plastics Capacitor, etc,
 > "designed for TC use" ruptured, spewing hot, messy oil all over the
 > room.  By your logic I will claim that commercial caps explode a lot and
 > get oil all over everything.  If I had to choose between a small fire on a
 > PCB and having to replace several $3.00 caps and cleaning up an oil slick
 > from a ruptured cap and spending several hundred bucks on a new cap, I'd
 > choose the former every time.
 >
 >
 > >Again, cornell dublier only makes residential and recreational capacitors.
 >
 > Actually this is utter rubbish.  They make a myriad of commercial and
 > industrial grade components that even a casual glance at their products
 > pages shows.  They also have a lot more OEM products not
 > listed.  "Recreational capacitors?"  Please....

You just don't get sarcasm. This is too bad. I'll explain. Any capacitor
churned out by the thousands in taiwan and sold in electronics catalogs in
commercial. Anything from Cornell Dublier is just as commercial as from
General Atomics. This term "commercial pulse cap" is more than not
improperly used and has no meaning anymore in this list. As for "pulse
cap" pretty much anything for energy storage is a pulse cap. This still
leaves lots of capacitors that are "pulse caps" that are no suitable in
any way for tesla coil useage. Take for instance extended foil mylar caps,
essentially beefed up filter caps. They are not a good choice for high
frequency AC usage.

If you can point out some "non-commercial" caps that are not made at home
by people, I'd like to hear about them.

 >
 >
 > >This nonsense "commercial pulse cap" term needs to go away, it has no
 > >meaning on this list. Like on ebay, people assume anything that says 
"tesla"
 > >or "high voltage" is somehow "commercial" and "a pulse cap", or that
 > >anything from Maxwell is rated the same. I'm pretty certain they make more
 > >than one capacitor, and they all have different ratings. Try 
substituting "I
 > >want to buy a Maxwell" with something as silly as "I want to buy a
 > >Nichicon".
 >
 > "Commercial pulse capacitor" = a self contained pulse-duty capacitor
 > purchased from a capacitor supplier like Maxwell, Plastics Capacitors,
 > etc.  An MMC is not a "commercial pulse capacitor," but a "home-made pulse
 > capacitor."  At least, this is my interpretation.  Perhaps we should come
 > up with more suitable terminology?

A MMC seems to be a homemade attempt at packaging off the shelf
components. You're not after a pulse so much as the ability to not
overheat, be really lossy or just fail really fast from high repetition
discharges at RF frequencies with voltage reverals nearing 100%. This is
far more demanding than "pulse cap" which any high voltage capacitor
manufacturer offers off the shelf with standard catalog part numbers that
you charge at DC, and dump into some friendly load with little ringing.


 >
 > Best regards,
 >
 > Mark Broker
 > Chief Engineer, The Geek Group
 >
 >
 >
 >