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Re: [TCML] Hello again

Hi Aric,

I ran a pair of MOTs for several years.  They held up fine until Katrina got them.  Mine were immersed in motor oil inside an old 30 cal ammo can.  Instead of using a 4-pack, I employed a voltage doubler to get roughly 11kvdc (peak).  This was sufficient to fire a small spark gap coil without the need for DC resonant charging.


Scroll down to the "power supplies" section.

I never suffered any leakage from the ammo can.  The rubber seal held up fine.  The oil did wick along the cotton cording inside the power cord one time, resulting in a small leak from the plug end.  A new power cord with solid vinyl insulation cured this issue.  I never had any other problems.

I'm still intrigued by MOT-powered Tesla coils.  I have a sizeable collection of salvaged MOTs waiting for me in my barn, if I ever get time to mess with coils again.


Gregory R. Hunter

--- On Tue, 10/20/09, Aric R <morevolts@xxxxxxxxx> wrote:

> From: Aric R <morevolts@xxxxxxxxx>
> Subject: [TCML] Hello again
> To: tesla@xxxxxxxxxx
> Date: Tuesday, October 20, 2009, 11:11 AM
> I've been an on again off again
> member of the Tesla list for over a decade.
> Just want to say hello to my friends old and new, and ask a
> question.
> I'm constructing a pair of transformer assemblies, each
> consisting of two
> microwave oven transformers with the primaries wired
> together anti-series,
> and the secondaries in series, thus allowing for about
> 4200VAC out of each
> unit, for 240VAC in.  One leg from each MOT secondary
> is grounded to the MOT
> chassis, and both MOTs in each assembly are bolted to an
> aluminum plate,
> such that the plate floats like a center tap for the
> secondaries.  The plate
> is electrically isolated from the housing, a .223 ammo can,
> using nylon
> spacers which clamp around the Al plate.  My intention
> is to immerse the
> transformers in oil, Vaseline, or wax, as one of the
> transformers in each
> assembly will be subjected to twice their designed
> dielectric stress when
> the lumped secondaries of each assembly are wired in
> series, and I'd also
> like to entertain the possibility of adding two more such
> modules to the
> series chain in the future.
> I wanted to know if anyone has constructed a similar
> device, using
> ammunition canisters.  They are equipped with
> substantial-looking seals, but
> I don't know if they are oil-proof.  It would make
> sense that they should
> be, as oil is often used to deactivate ammunition, but I'd
> like to learn for
> another's experience if this has been attempted. 
> Also, I'd like opinions on
> whether canning wax would be sufficient in this
> application, as I'd just as
> soon not have to deal with leaking transformer oil.
> I've hi-pot tested one of the assemblies, and in air, the
> floating Al plate
> shorts to the grounded ammo can at around 7KV.  This
> is before deburring the
> edges of the plate, and rounding the corners (the discharge
> point was always
> the same plate corner).
> Electrical connections will be realized through the use of
> ceramic
> feedthrough insulators for the secondary terminals, and
> homemade plastic
> feedthrough insulators for the primary.
> Aric Rothman
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