Re: Yet Another Lo-Budget MOT Experiment

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

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.

Cheers,

Paul Benham.

----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <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
<twftesla-at-qwest-dot-net>" <jolyon-at-vatercox.freeserve.co.uk>
 >
 > 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!
 >
 > Jolyon
 > ---- 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
 >  >
 >  > _
 >
 >