Re: Hello again / New MOT coil (fwd)

["Tesla list" <tesla@xxxxxxxxxx>]

---------- Forwarded message ----------
Date: Wed, 18 Jul 2007 18:19:22 -0400
From: Jason Johnson <jasonmsusolar@xxxxxxxxx>
To: Tesla list <tesla@xxxxxxxxxx>
Subject: Re: Hello again / New MOT coil (fwd)

Greg,

I tried using the level shifter type setup, but I blew two strings of diodes
within the first 30 seconds of runtime. I decided at that point to go
without the level shifter and power the coil with only 4200 volt input. This
change from 12 kvdc to 4.2 kvac input meant that I had to rewire the MMC and
the filter circuit. The MMC had already been soldered into a 3 x 10
arrangement (for 45 nF at 20 kvdc), so this limited my easy option to a 6 x
5 setup (for 180 nF at 10 kvdc). If you look at the picture of the MMC, I'm
sure you'll see why this was the easiest rewiring option. As far as the
filter circuit rewiring, I just soldered a wire across 2 of my MOVs, giving
me 8 series MOVs instead of the 10 I had previously.

Of course, going to such a low input voltage demands a big capacitor, and
very tight tolerances in the spark gap. I found that if I closed the gaps as
tight as my setup would allow, the spinning electrode would expand upon
heating and jam up in the stationaries. With this in mind, I opened the gaps
to about 0.060", and this seems to run very well. It takes about 75 volts
input with no tank circuit to fire this, and about 65 volts input with the
tank hooked up (obviously some voltage rise due to the caps resonating with
the transformers and variac).

Jason


On 7/18/07, Tesla list <tesla@xxxxxxxxxx> wrote:
>
>
> ---------- Forwarded message ----------
> Date: Tue, 17 Jul 2007 19:08:54 -0700 (PDT)
> From: G Hunter <dogbrain_39560@xxxxxxxxx>
> To: Tesla list <tesla@xxxxxxxxxx>
> Subject: Re: Hello again / New MOT coil (fwd)
>
> Are you firing this coil with 4200vac straight from
> the MOT twins?  No voltage multiplier?
>
> Greg
> (http://hot-streamer.com/greg)
>
> --- Tesla list <tesla@xxxxxxxxxx> wrote:
>
> >
> > ---------- Forwarded message ----------
> > Date: Tue, 17 Jul 2007 18:33:03 -0400
> > From: Jason Johnson <jasonmsusolar@xxxxxxxxx>
> > To: tesla@xxxxxxxxxx
> > Subject: Hello again / New MOT coil
> >
> > Hi all,
> >
> > I have been away from the list for several years
> > now, though I have recently
> > returned to the hobby of Tesla coiling. Over the
> > past year or so I have been
> > putting a new coil together, which I recently
> > completed. It is powered by
> > two MOTs, with a big MMC and an asynchronous
> > propeller style rotary gap. I
> > put a simple webpage together to detail the coil
> > with pictures and such, you
> > can find it at:
> >
> >
>
> http://mse-gsd1.matsceng.ohio-state.edu/~glenn/jason/Tesla%20site_files/page0001.htm
> >
> > This website is hosted by the professor I currently
> > work with at Ohio State
> > University, his page may be of interest as well - he
> > does research into
> > electromagnetic forming of sheet metal. Basically
> > quarter shrinking, but
> > slightly more productive. Just go up a directory to
> > (
> > http://mse-gsd1.matsceng.ohio-state.edu/~glenn) to
> > check out some high
> > velocity metal forming stuff.
> >
> > Let me know what Y'all think!
> >
> > Regards,
> > Jason
> >
> >
> >
>
>
>
>
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