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Re: static "sucker" gap / cap stress
Original poster: "Jeremy Scott by way of Terry Fritz <teslalist-at-qwest-dot-net>" <supertux1-at-yahoo-dot-com>
There was an array for sale on ebay that had six of
them. Went for $220 ... I missed it unfortunately.
I got mine anywhere from $50 - $70 so that's
pretty typical. Consider they go retail for
several hundred dollars each.
I would be very careful using just one of these
in a 5KVA coil. I'm guessing here, that you're
using a pole pig right? You'll especially
want an array if you're using resonant charging.
Considering that in a 15Kv system the cap's
voltage is 21Kv, one or two successive misfirings
of your gap will drive the capacitor over it's 35KV
rating if you fail to have any other safety gaps.
I had one in a high power system and it overheated
and ejected it's internals out of that little
belly button above the connection disc on the side.
Since I've doubled up the voltage, it's been fine.
Hard to go wrong using 70Kv for a 21Kv peak system.
You might also want to note some values on that
spec sheet, specifically those referring to
"voltage Reversal." This cap was designed to
be a DC capacitor -- it happens to work well
for AC if you give it lots of room. (That's
500 pps DC --- AC puts significantly more
stress on anything, so it's really less for
our usages)
If you do build a box, use some springy bent
strips of flat copper to lay against the
terminal disks of the capacitor. Ie, design an
enclosure that is similar to battery packs.
(Sand the copper terminals every once in awhile
to get rid of the oxidation) I don't recommend
using the small screw hole w/ crimp lugs etc...
I like to build things into nice hardwood boxes
with routed edges and what not. I'd much rather
get hit with a splinter of wood than a chunk of
metal/hdpe/hot oil. Also your coil setup will
look like furniture if you take the time to sand
and stain it :) It won't look as scary and it'll
be safer. I guess that's the artist in me. I
design my coils to be visually pleasing when
turned off,safe and as scary as hell when turned on.
--- Tesla list <tesla-at-pupman-dot-com> wrote:
> Original poster: "Christoph Bohr by way of Terry
> Fritz <teslalist-at-qwest-dot-net>" <cb-at-luebke-lands.de>
>
> Hi!
>
> Good to find someone who knows the cap, although I
> think I have seen them on
> some coils on the net.
> I got mine from alltronics on ebay for 50$, think
> this was OK. It came
> without a label but with the catalog number
> scratched into the housing.
> I thought about buying another one, Tesla Systems
> Research is offering them
> for 73$ I think...wonder if the price is OK.... I
> initially bought this one
> because I was looking for extra security, hearing
> that they can blow up too
> is really disappointing....I have to do most coiling
> indoors.
> At the moment I am transferring roughly 5 KVA
> through the system, maybe that
> is too much for a single cap, but your Idea with the
> "emergency shut off "
> via temperature sensing seems really good and I'll
> probably build something
> like this and with the new information shielding
> will surely be installed
> next time.
> Do you think I should buy another cap? or is any
> other maxwell type better
> suitable? or MMC.....at least MMCs seem to be "blow
> up friendly" for indoor
> use.
> BTW: I checked my spec paper again and its really
> has a line in it which
> says: max continuos rep rate: 500 PPS....I thought
> this means 500 shots per
> second....but that was probably wrong after what you
> said....or I might have
> the wrong spec sheet.
> My sheet can be seen at
> http://www.luebke-lands.de/media/20P005.pdf maybe
> you can have a llok at it or hand me a link to your
> paper....
>
> Thanks for your support!
>
> sincerely
>
> Christoph
>
> ----- Original Message -----
> From: "Tesla list" <tesla-at-pupman-dot-com>
> To: <tesla-at-pupman-dot-com>
> Sent: Thursday, April 24, 2003 7:26 AM
> Subject: Re: static "sucker" gap / cap stress
>
>
> > Original poster: "Jeremy Scott by way of Terry
> Fritz
> <teslalist-at-qwest-dot-net>" <supertux1-at-yahoo-dot-com>
> >
> > Hi,
> >
> > I use the exact same Maxwell cap in my systems,
> > however I double them up, that is, I use four
> > in a parallel series configuration. .03uf, 70Kv
> > for nice long runs. They are oil filled which
> makes
> > them nice bombs when they do blow up. I'm
> thinking
> > of enclosing mine in a nice hardwood box with a
> fan
> > and maybe one of those CPU temperature display
> > thingys.
> > (Idea: wire a thermistor into relay circuit that
> > controls power to the transformer.)
> >
> > If you look at the spec sheet from Maxwell you'll
> > find that they aren't rated for continuous
> stress.
> > (They're really designed for the occasional one
> shot
> > brief discharges: X rays, MRI's and that sorta
> thing.)
> >
> > The fact that they even last in a tesla circuit
> is
> > testament to Maxwell quality. I've seen one cut
> > up and there were plenty of black little holes
> > that were the result of a puncture, but the cap
> > fixed itself and before disassembly remained
> fairly
> > close to it's original value.
> >
> >
> > --- Tesla list <tesla-at-pupman-dot-com> wrote
> > > Original poster: "Christoph Bohr by way of
> Terry
> > > Fritz <teslalist-at-qwest-dot-net>"
> <cb-at-luebke-lands.de>
> > >
> > > Hello everybody.
> > >
> > > After experimanting with RSG's I made a little
> > > excursion back to static gaps.
> > >
> > > I built a sucker gap with 2 elektrodes and
> attached
> > > an ordinary vacuum
> > > cleaner to it. ( ordinary design....t-shaped
> sewer
> > > tube and 2 copper tubes )
> > > The results with my current magnifier were
> > > disappointing as the quenching
> > > seems not to be too good.
> > > But with the ordinary 5" setup I got really
> hot
> > > white steamers to the
> > > ceiling space-limited by the walls to 4 feet.
> > > The power in the arcs must have been really
> big,
> > > they almost looked like a
> > > time-exposure.....only real ;-)
> > > This mus be due to the high current the
> MOT-Supply
> > > can deliver.
> > > The break rate seemed very high, estimated
> between
> > > 400 and 800 bps.
> > > Only problem that occoured: THe tank cap got
> warm,
> > > nit really hot but
> > > palpable after some 20 second runs at roughly
> 5KVA (
> > > no PFC ).
> > > I use a Maxwell 37667 Type cap, 30nF and 35KV.
> Is
> > > this cap to weak for this
> > > arrangment or do I do something wrong that
> puts
> > > stress an the cap.
> > > Tuning was done at 1KVA before I turned to
> higher
> > > power levels....but the
> > > effect of streamer-loading shouldn't affect
> the
> > > tuning too much.
> > >
> > > My personal results:
> > >
> > > Pros: The sucker gap really performs well and
> is
> > > extremely cheap and easy
> > > to build and seems to be very robust, a good
> choice
> > > and a really good
> > > performer in my system at
> least.
> > >
> > > Cons: the noise really requiers hearing
> protection,
> > > I loosend one of my
> > > earmuffs for a moment an was really
> > > shocked.....luckily noone was at home
> > > at this time.
> > > Bad performance with my magnifiers
> > > although I read about people
> > > using them succesfully with maggies. I will go
> for
> > > high bps RSG with that I
> > > think, perhaps with
> > > sucker gap in series to aid
> quenching.
> > >
> > > Questions to be solved: Cap heating.....is it
> bad or
> > > not......dont want to
> > > destroy it as its my only professional pulse
> cap.
> > >
> > > I hope I don't mess up the list with such
> "low-level
> > > posts" but I like to
> > > share results as sometimes it might be usefull
> for
> > > other users,too ...
> > >
> > > happy coiling
> > >
> > >
> > > Christoph
> > >
> > >
> >
> >
> >
> >
>
>
=== message truncated ===
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