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Re: MOTs Rule!

MMC's cost ��� to build, OK not very much but nevertheless some. MOT's
on the other hand are free, and therefore, even if you have loads of
them (to build a www.altair-dot-org style isolation/level shifter), they
still cost nothing. It is cheaper to blast the crap out of an
in-efficient coil, than to make an in-efficient coil more efficient.

Long live resistive ballasting, single piece static and async RSG gaps
and MOT's.

Max the Budget Master.

Tesla List wrote:
> 
> Original Poster: "Reinhard Walter Buchner" <rw.buchner-at-verbund-dot-net>
> 
> Hi Greg, all,
> 
> Comments interspersed.
> 
> > Original Poster: "Gregory R. Hunter" <ghunter-at-accucomm-dot-net>
> 
> > I've just tested my twin MOT supply with dual voltage doublers on my
> >4" x 24" coil.  The supply is based on two MOTs salvaged from
> >discarded 900 Watt ovens.  I borrowed the idea for it from Finnish
> >Coiler Marco Denicoli. I normally run the coil with two 9KV/60ma
> >neons.  I use a single static vacuum gap made of 1" copper pipe
> >fittings (yes, beefy) and a .023uF MMC. Toroid is 3.5" x 14".  I had
> >to close the gap a little to get reliable firing from the MOTs, so I'm
> >guessing voltage is in the 8KVAC range. I used no ballast--the MOTs
> >go as hard as they want to.  I ran the vacuum cleaner motor on my
> >gap at full throttle in hopes of quenching the higher current.
> 
> Ahhh. Another low voltage coiler ;o)). I don�t like MOTs (see my mail
> from last week as to why), but you aren�t overvolting your dual MOT
> setup, as long as you ground the "center tap" between the two MOTs.
> However, I doubt your gap will quench properly at this power level.
> It doesn�t matter how hard your "blower" is running. It�s just too much
> power (1800VA as of the spec plate). Your setup is probably giving
> you MUCH more power as the MOT shunts don�t work in a true short.
> As you are only using 2 MOTs, a normal 3 piece safety gap will provide
> your MOTs with adequate protection.
> 
> > Results were pretty satisfying.  The streamers aren't any longer than
> >with the NST supply, but they are much thicker, brighter, more
> >intense, and more chaotic. They look as hot as lightning bolts.  There
> >also seem to be more of them.  The spark gap sounds different too
> >--much lower in pitch--almost a mechanical grinding sound.
> 
> You made up for a MUCH stiffer PSU and didn�t change the primary
> cap, so what you are seeing, is the effect of what increased BPS
> does to your TC output. If you switch over to a SRSG, your spark
> length will increase (in my opinion) dramatically. If you then increase
> your primary cap (don�t go LTR, tho, it will become ridiculously large),
> you would be set for large sparks. Guessing, I would say it is time to
> build a larger secondary. That 4" isn�t gonna survive that kind of
> power for long ;o))
> 
> >It gives me the creeps.  Best spark length is about 30" (to my strike
> >rail), and rarely a single streamer may reach out 36" or so.  This
> >thing really wants a bigger tank cap & larger toroid. I plan to remedy
> >both very soon.
> 
> Yes, do so. You�ll love the results. With a SRSG and a bigger cap,
> (and more secondary), I don�t think 80+" are unobtainable. However
> keep a close watch on those MOTs. They may not last for long (I
> bet they get pretty warm already). DON�T go for mains resonance
> during cap design. Rather, increase your breakrate. I�d shoot for
> 240 bps (200 if your a 50Hz coiler). Also remember, due to your low
> voltage AND your big cap, you will be running a large (TC) primary
> current, which calls for beefy components.
> 
> > I may even immerse the MOTs in oil to enhance cooling.
> 
> I WOULD do this, but not only because of cooling, but rather for
> insulation reasons. MOTS ARE just as fragile to overvoltage as
> NSTs are, if not even more so.
> 
> > Low budget coilers unite!  MOTs rule!
> 
> Remember, the (E)MMC has it�s price based upon the Joules it
> can store. It won�t make a (noticeable) difference in price if you
> build a 5 Joule MMC cap using high voltage and low capacity or
> if you build that same 5J (example) cap for low voltage and high
> capacitance. However, reconfiguring an already built (E)MMC
> is as near as your soldering iron ;o)).
> 
> Coiler greets from Germany,
> Reinhard