Convert your MOT to NST?

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

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