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Re: MOT power supply



Original poster: "Christopher Telford by way of Terry Fritz <twftesla-at-uswest-dot-net>" <christophertelford-at-yahoo-dot-com>

Hello Henry, 

I built the MOT supply with voltage doublers. The
trouble is, i think the diodes have broken. When i
plugged it in it just sat there humming ominously. To
further test this theory, i removed the diodes,
leaving the two MOT's with seriesed secondaries for
maximum voltage and the two capacitors that should
have been part of the voltage doubling circuit. This
seemed to work very well. Slightly better than the two
NST's that i currently use in terms of length, and
better by far in brightness. Unfortunately, then
longer i ran it the shorter the sparks became. The
reason for this i think is that the spark gap wasn't
up to the power levels i was using. After running for
30 secs the gap was very hot (i disconnected
everything before checking this) and the smaller of
the seperations seemed to have been welded shut!
The gap is a multiple statice air gap. 
The current was limited only by the two capacitors
that were part of the voltage doubler circuit. If i
use no limiting at all then the light dimms, and the
fuse blows after 10 secs or so. I don't do this
anymore as i am running ot of fusses. If i use a third
MOT core as balast then the performance is much less. 
I don;t understand why the diodes stopped working. I
use three, rather than the recommended two, which
should make them even less likely to blow. The two
capacitors i use where slightly different in value,
but not much (no mroe than 10% difference. I don't
know if this could be the reason or not. 

Thanks for any advice, 

Chris Telford
--- Tesla list <tesla-at-pupman-dot-com> wrote:
> Original poster: "by way of Terry Fritz
> <twftesla-at-uswest-dot-net>" <Hhchicken1-at-aol-dot-com>
> 
> Hi Chris, 
> If you have the microwaves and not just the MOTs, I
> really recommend using 
> the simple voltage doubler circuit I mentioned.  All
> the required components 
> are in the microwaves, and it will definitely
> improve performance by stopping 
> power-arcs from taking place at the main spark gap. 
> I tried my coil with 
> just two MOTs and no doubler, and it ran OK for
> about 5 seconds before the 
> gap power-arced and the streamers dropped to less
> than an inch long.  I've 
> sent a copy of the schematic to
> terry-at-hot-streamer-dot-com so it should be posted 
> at:
> http://hot-streamer-dot-com/temp/mot.bmp
> 
> - Henry 
> 
> In a message dated 02/01/01 14:16:51 GMT Standard
> Time, tesla-at-pupman-dot-com 
> writes: 
> 
> 
> >
> > Hello Henry, Jason and Bert, 
> >
> > Thanks for the advice, it was really useful.
> Hopefully 
> > now i won't kill myself :-). I just went to the
> local 
> > tip, and managed to get hold of 2 MOT's from 850
> and 
> > 950 watt ovens. Also on the way back from the tip,
> i 
> > found another microwave that someone had chucked
> on 
> > the grass verge, so i got that too. I havn't
> tested 
> > any of them yet, but they all look like they'l
> work. 
> > I'll post a message to tell u how well my Tesla
> coil 
> > goes with them as the power supply if i get any 
> > itneresteing results. I was quite supprised to
> manage 
> > to get any MOT's, let alone 3! 
> > I plan to use them in series on the secondary side
> and 
> > parallel on the primary for around 4800 volts. I
> hope 
> > this will be enough. I am going from my 450W NST
> to 
> > whatever the MOT's provide, so i doubt i need to
> be 
> > 100% efficient with the power to get an
> improvement. 
> > Thanks, 
> >
> > Chris Telford 
> 
> 
> 
> 
> 
> 


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