RE: MOT-powered coil questions

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

Original poster: "Steve K by way of Terry Fritz <teslalist-at-qwest-dot-net>" <teslainnovations-at-yahoo-dot-com>

Greg,

I am currently working on a 6kva, 4 MOT coil, and am
STILL having a hard time with quenching the gap. I was
using a sucker-gap powered by a 10 amp shop vac,
supposedly able to handle 10kva, and got very
dissapointing results. Not only did I have to set the
gap very close, the brass gas jet fittings I was using
started to melt in under a minute of on/off operation.
  Next I will try a high speed rotary gap that I just
finished up today. Hopefully the tungsten will hold up
better than that brass!
.... Well anyway, I would suggest using microwave oven
caps to boost the voltage and limit the current, and
at least 4 MOTS or 2 with a doubler... I am sure
someone on this list can tell you more about it...
  If you haven't had much experience in coiling, I
would forget the MOTS and go for a few NSTs in
parallel!

  Steve Klec

--- Tesla list <tesla-at-pupman-dot-com> wrote:
 > Original poster: "Dwight Harm by way of Terry Fritz
 > <teslalist-at-qwest-dot-net>" <dwighth-at-traxsoft-dot-com>
 >
 > Gregory,
 > Thanks to you & everyone for all the good advice.
 > You're understanding of
 > our situation is quite right, and it makes sense
 > that a low-voltage,
 > high-current gap would be much harder to quench.
 > We'll take a little time &
 > figure out if we want to go 4-MOT, or 2-MOT with a
 > voltage doubler.  Your
 > webpages have a wealth of info on that!  Good thing
 > we saved the diodes from
 > the MO's!
 >
 > Dwight & Greg.
 > (Yes, my son's name is Gregory, too!)
 >
 >  > -----Original Message-----
 >  > From: Tesla list [mailto:tesla-at-pupman-dot-com]
 >  > Sent: Wednesday, May 28, 2003 6:13 PM
 >  > To: tesla-at-pupman-dot-com
 >  > Subject: Re: MOT-powered coil questions
 >  >
 >  >
 >  > Original poster: "Gregory Hunter by way of Terry
 > Fritz
 >  > <teslalist-at-qwest-dot-net>" <ghunter31014-at-yahoo-dot-com>
 >  >
 >  > OK Dwight,
 >  >
 >  > I stand corrected. Apparently, the lower limit
 > for
 >  > spark gap tesla coil supply voltage has yet to be
 >  > established. Perhaps someday under the guidance
 > of
 >  > this sage group, you can dispense with the
 > transformer
 >  > altogether, and fire a coil directly from 120vac
 > wall
 >  > current. However, I'm going to go out on a limb
 > here
 >  > and assume that you are not interested in micro-
 > or
 >  > flea-power coiling for your first effort, nor are
 > you
 >  > interested in sub-kilovolt spark gap research. If
 > I
 >  > correctly understood your initial query to the
 > list, I
 >  > believe you are interested in building a
 > practical,
 >  > MOT-based Tesla coil, and that you are seeking
 > useful
 >  > advice to that end. If this is so, then based on
 > my
 >  > limited experience, I suggest that 4kvac from a
 > pair
 >  > of MOTs is a tough way for a novice to start out.
 >  > Quenching a low voltage/high current arc presents
 >  > difficult design challenges that most newbies
 > would do
 >  > better to avoid. Raising the voltage a bit with a
 >  > level shifter, or by simply using 4 MOTs instead
 > of 2,
 >  > sidesteps many problems and greatly simplifies
 > spark
 >  > gap design. If you'd like to hear more of my
 >  > half-baked ideas on MOT power supply design for
 > tesla
 >  > coiling, please refer to my various primers on
 > the
 >  > subject.
 >  >
 >  > http://hot-streamer-dot-com/greg/MOT_chat.htm
 >  > http://hot-streamer-dot-com/greg/MOTDOC.htm
 >  > http://hot-streamer-dot-com/greg/4pack.htm
 >  >
 >