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Re: Maxwell VS. MMC capacitors
Original poster: dgoodfellow-at-highstream-dot-net
I performed a simple comparison based on what I had access to. Many are
responding to this thread about which is "better". We haven't qualified what
better means yet. Better value? Better durability? Better streamers? Better
on nst's or big power? If there is a member that has the resources to
perform a similar test to what I did, except with all new components, then
I'm sure we would all be interested in the results. Do you think that new
Maxwells would have performed dramatically better than what I photographed?
As far as how many pulses the surplus cap has had before it became part
of a Tesla coil, well, I have absolutely no idea how many pulses the
Maxwells sustained during the 4 or 5 30 second operations we performed for
the comparison. The Maxwells have a life expectancy printed on the label. I
don't know what that translates into in terms of Tesla coil duty, I'm not
that good to where I can figure it out on my own. I can't imagine the
Maxwells ever failing they way I had the four of them in series on the 15/30
nst. Maybe I'm wrong? I had the spark gap set at your recommendation of
around .200" because it was a conservative test, not an "all out" run with
everything pushed to the limits.
Again, I was not out to set a spark record using one capacitor or the
other, I just wanted to do a side by side comparison of the CD caps and
Maxwells. My friend bought the Maxwells on ebay just before I discovered the
Tesla list. We knew the Maxwells were good capacitors, we wanted to see if
the CD's worked as well. Once again, I am delighted that we have a GREAT
alternative capacitor to what we used to have just a few years ago. When
most of the members of this list ask "Which is better" you can bet that
over 90% of them are scroungers, and the question is really "Are used
Maxwells better than Geek caps" My comparison suggests that a hobby
coilbuilder will be ahead (financially) by buying Geek caps. Few people as
hobbyists will be willing to pay so much (as the cost of new Maxwells) for a
component of a device (the Tesla coil) that has virtually no useful purpose.
If my comparison of new against used was biased, then so be it. I made no
claims which is "better" except that new CD caps are affordable, reliable,
and available. You won't find me complaining about a failed Maxwell, my
finances won't allow me to buy one, new or used!!
Cheers, Dave
----- Original Message -----
From: Tesla list <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Sunday, February 29, 2004 1:11 AM
Subject: Re: Maxwell VS. MMC capacitors
> Original poster: "Dr. Resonance" <resonance-at-jvlnet-dot-com>
>
>
> If you're going to do some testing be sure to buy the Maxwell caps NEW and
> compare them to NEW MMC's. Most experimenters buy used/surplus Maxwell
caps
> and then complain about early failure. They have absolutely no idea how
> many pulses the surplus cap's dielectric has sustained so any test is
> totally unfair.
> In scientific terms, using used caps totally invalidates the comparison
> experiment --- in scientific terms it's called prejudice.
>
> Dr. Resonance
>
> Resonance Research Corporation
> E11870 Shadylane Rd.
> Baraboo WI 53913
> >
> > >I think you being unfair in comparing the cost of one cap that's ten
> times
> > >bigger than it needs to be to an other cap.
> >
> > When we tested the Maxwells against the CD capacitors, we were looking
> > primarily for the same capacitance, not the same dc voltage rating. The
> > Maxwells that we used are the ones that are perhaps most commonly
featured
> > on ebay, the .03uf, 35kv (Maxwell#37667) capacitors. If we had a
Maxwell
> > 37xxx series that happened to be a .0075uf 35kv capacitor, we would
have
> > used it instead of four .03uf capacitors. We were looking for good
sparks
> > from a 15/30. It took 4 Maxwells in series to give us the capacitance
we
> > were looking for. That's as scientific as it got. We got good sparks
from
> > both capacitor banks. The 14 CD caps gave us .00714uf and ran for long
> > periods without getting warm. The Maxwells gave us .0075uf which also
did
> > not get warm after long runs.
> >
> > There was no need to build a capacitor bank from cd caps (4 strings of
> 70ea.
> > .15uf/2kv) to match the dc voltage rating to the Maxwells. I was not
even
> > using the Geek caps in my test. Geek caps are 2kv, the CD caps I used
were
> > rated at 1600 volts dc. 1600 x 14 =22,400vdc and we were using a 15/30
on
> > them. 14 capacitors divided by 15,000 volts = 1,071 VAC on each
capacitor,
> > rated for 1600 volts DC. The CD capacitor bank has stood the test of
time,
> > and it is a testimony to how well they are built that they didn't flat
out
> > fail, running so close to the edge.
> >
> > >If you factor that in the Maxwell is just $24 i.e. half the CD caps.
or
> > >make the CD MMC 10x bigger then it costs $500
> >
> > Do you know someone selling Maxwells for $24??
> > I'm not sure what you are getting at, but if you want to compare apples
to
> > apples, I'm game....
> >
> > for both capacitor banks to be dc rated at 140kv........
> >
> > 280 New, Unused Geek group caps at 3.00 ea..... $840.00 Plus
> shipping
> > 4 New, Unused Maxwells that list for over $600.00 each... $2400.00
Plus
> > shipping
> >
> >
> > As I said before, pay more if you want to, but you will be ahead of the
> game
> > with the MMC!
> >
> > The CDE cap coil run can be seen here:
> >
> > http://hot-streamer-dot-com/temp/16pflex.jpg
> >
> >
> > Maxwell cap coil run can be seen here:
> >
> > http://hot-streamer-dot-com/temp/maxwellcapsa.jpg
> >
> >
> > Ebay caps such as are illustrated in our simple experiment can be seen
> here:
> >
> >
>
http://cgi.ebay-dot-com/ws/eBayISAPI.dll?ViewItem&item=2597967164&category=4662
> >
> >
> >
> > >I had assumed the CD caps where cheaper than even used Maxwells. I
need
> to
> > >check out ebay again.
> > >Even at twice the price you could say you know what your getting with
> the
> > >MMC. If its bang for your buck it may be worth the risk of a ebay Max
> >
> >
> > Build it, test it, let us know what happened, that's what I did :-)
> >
> >
> > Dave Goodfellow
> >
> >
> >
> > ----- Original Message -----
> > From: Tesla list <tesla-at-pupman-dot-com>
> > To: <tesla-at-pupman-dot-com>
> > Sent: Saturday, February 28, 2004 4:46 PM
> > Subject: Re: Maxwell VS. MMC capacitors
> >
> >
> > > Original poster: "Robert Jones" <alwynj48-at-earthlink-dot-net>
> > >
> > > Hi,
> > >
> > > ----- Original Message -----
> > > From: "Tesla list" <tesla-at-pupman-dot-com>
> > > To: <tesla-at-pupman-dot-com>
> > > Sent: Saturday, February 28, 2004 9:09 AM
> > > Subject: Maxwell VS. MMC capacitors
> > >
> > >
> > > > Original poster: dgoodfellow-at-highstream-dot-net
> > > >
> > > >
> > > snip
> > >
> > > >
> > > > I realize that there are 2 transformers in the picture
> > > > with the Maxwells in it, but I can assure you that only one of
the
> > > > transformers was powered at the time of the photos. I think that
4
> > > Maxwells
> > > > could handle the 15/30 for some time since they are rated at
35,000
> > volts
> > > > each, so 4 in series puts them at 140,000 volts, a factor of
nearly
> 10
> > > times
> > > > the operating voltage.
> > > > Cost of the cornell dubilier capacitor bank.......under $50.00
> > > > Cost of the Maxwell
> > > > bank..............................................$240.00 (for 4)
> used
> > off
> > > ebay
> > >
> > > I think you being unfair in comparing the cost of one cap that's ten
> times
> > > bigger than it needs to be to an other cap.
> > > If you factor that in the Maxwell is just $24 i.e. half the CD caps.
> or
> > > make the CD MMC 10x bigger then it costs $500
> > >
> > > I had assumed the CD caps where cheaper than even used Maxwells. I
need
> to
> > > check out ebay again.
> > > Even at twice the price you could say you know what your getting
with
> the
> > > MMC. If its bang for your buck it may be worth the risk of a ebay
Max
> > >
> > > Bob
> > >
> > >
> > >
> >
> >
> >
>
>
>