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Re: Yet Another Lo-Budget MOT Experiment
Original poster: "Paul Benham by way of Terry Fritz <twftesla-at-qwest-dot-net>" <paulb-at-woodanddouglas.co.uk>
I am in the process of building a DC PSU for my tesla coil. One thing that
I have planned is resonant charging with a triggered gap. I was going to
fire an ignition coil which would trigger the gap. The ignition coil will
be fired when the voltage across the gap reaches a preset level by
monitoring the voltage with a voltage divider. This would then give a very
repeatable firing voltage for experimentation.
The DC PSU is built, and I am building up a resistor to charge my capacitor.
When this works I will add a DQing diode and charging choke.
----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
Sent: Tuesday, November 12, 2002 2:23 PM
Subject: Re: Yet Another Lo-Budget MOT Experiment
> Original poster: "Jolyon Vater Cox by way of Terry Fritz
> Have you considered using a triggered gap with the MOTs?
> How about using an ignition coil to supply pulses at higher voltage but
> lower current than the MOTs to gate the main discharge?
> which would be triggered when a spark from one of the main electrodes
> attached itself to the ionized channel of a "pilot" spark between the
> trigger electrode and the other main electrode -"closing the switch" so as
> to speak.
> Maybe you could even try a "pseudo-spark" -switch
> they are supposed to be very fast- although I don't know if anyone on the
> List has ever used these or whether it is feasible to build them without
> specialised equipment!
> ---- Original Message -----
> From: "Tesla list" <tesla-at-pupman-dot-com>
> To: <tesla-at-pupman-dot-com>
> Sent: Monday, November 11, 2002 7:50 PM
> Subject: Yet Another Lo-Budget MOT Experiment
> > Original poster: "Gregory Hunter by way of Terry Fritz
> <twftesla-at-qwest-dot-net>" <ghunter31014-at-yahoo-dot-com>
> > Dear List,
> > I just tried the low-voltage high-current approach
> > again using only two series MOTs for ~4kvac, no
> > doublers, no RF filter, and no ballast. Power was
> > provided by a 240vac/20A window A/C outlet:
> > http://hot-streamer-dot-com/greg/madness7.jpg
> > The Tesla coil was my new & improved junk box coil
> > with a new primary, 4" sch 40 PVC wound for 24" with
> > 28AWG. Top load was 4" x 20" dryer duct toroid. Tank
> > cap was 128nf (81nF of beer bottles in parallel with
> > 47nF MMC). Spark gap was inside-out sucker gap
> > quenched with a vacuum cleaner motor (air blown single
> > static).
> > Performance was pretty good--better than I expected
> > anyway. The gap setting proved to be hyper-critical. A
> > micron too wide, and firing was sporadic. An angstrom
> > too narrow, and it quickly decayed to power arc. Once
> > I got it set just right, I could run a couple of
> > minutes or more before I felt compelled to switch off
> > the MOTs so the gap could cool awhile.
> > Sparks were thick, intense, and frantic. I got plenty
> > of strikes out to 5 feet or so, which sort of
> > surprised me. I might have to try this again with a
> > water or oil cooled gap. I also noticed my motor oil
> > immersed MOT twins got very hot. I cracked the lid of
> > the ammo can and a puff of oil smoke came out! Maybe a
> > bigger oil bath is in order!
> > I'm still not satisfied with the utility of this
> > setup. Going up to 8kvac with 4 series MOTs solves so
> > many problems and makes things more stable and
> > predictable. Still, I intend to do some more 4kv
> > experimenting--just for grins.
> > Regards,
> > =====
> > Gregory R. Hunter
> > http://hot-streamer-dot-com/greg
> > _