Re: Convert your MOT to NST?

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

Original poster: "Jason Petrou by way of Terry Fritz <twftesla-at-qwest-dot-net>" <jasonp-at-btinternet-dot-com>

Steve,

Good idea - however...

When you run an iggy coil with a dimmer and cap setup, you get a nasty
ringing in the primary circuit of the dimmer with the cap, and this is
reflected back into the output of the ignition transformer. This will happen
also with a MOT. Also, the waveform from the MOT will be out of pahse if you
are using a rotary, and not at all sine shaped, with many nast cap-killing
voltage paks. If you've got a scope, try it and see!

Best Regards,
Jason

{UK Geek #1139 ¬ G-2}
----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Wednesday, January 23, 2002 3:18 AM
Subject: Convert your MOT to NST?


> Original poster: "S & J Young by way of Terry Fritz <twftesla-at-qwest-dot-net>"
<youngs-at-konnections-dot-net>
>
> Hi list,
>
> MOTs are sometimes used to power TCs.  MOTs are typically free, don't
break
> down like NSTs often do, and are good for 1 KVA or so.  On the downside,
the
> 2 KV voltage is on the low side, requiring 2 or 4 in series and/or voltage
> multipliers, and the current is rather high, making it tough to cool and
> quench spark gaps.  And their self-current limiting (magnetic shunts) are
> not all that effective.
>
> Can these limitations be overcome?  Yes, sortof.   I tried an experiment
and
> got around 10 KV out of one at reduced current - probably 100 ma or so
> average.  How?  By driving the MOT from a lamp dimmer and 15-30 mFd cap in
> series.  Same idea as driving an ignition coil for a TSG, only with more
> input power.  The voltage is much higher than normal because of the more
> rapidly changing magnetic field, and the average current goes down because
> power is applied for only part of a cycle.
>
> The insulation of the MOT I tried did not break down for output arcs that
> would bridge 1/4 to 3/8 inch.  It would be a good idea to immerse a MOT
run
> this way in oil to improve its chances for long term survival.
>
> Using just a straight dimmer, the operation was a bit flaky, as others
have
> reported in trying to drive an inductive load.  I didn't try adding a
second
> triac, but I am sure that would improve performance a lot.
>
> So one can get NST-like performance out of a MOT if driven in this unusual
> way.  A pair of them would be good for 16-20 KV at a 100 ma or so,
depending
> on the size of the series cap used (use motor run caps).
>
> Just something to consider and tinker with if you are so inclined.
>
> --Steve
>
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