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Re: MOT



Hi Henry,

Good questions!  Your post certainly stirred up a lot
of interest.  You have guessed correctly that the
winding with only a few turns provides low voltage for
the magnetron tube filament.

Actually, there is a way to extract higher voltage
from the MOT by applying mains voltage to the filament
winding.  I did something similar with a US MOT by
applying 120VAC to the filament winding through a
solid state lamp dimmer switch and 7uF of motor start
caps.  My MOT was able to fire a .25 inch spark gap
continuously, with no hint of failure or internal
arcing.  Eventually, I'd like to try a bigger series
cap to increase the power a little.

So why didn't my MOT instantly saturate? Because
Dimmer switches, of both the US and Euro variety,
employ a fast, bidirectional switch called a TRIAC. 
The TRIAC switches on so suddenly that the MOT has
time to produce an impressive high voltage pulse
before it saturates.  Also, the series motor start cap
prevents runaway current after the TRIAC switches on.

With a MOT, a dimmer switch from a DIY store, and a
few motor start caps, you might be able to cobble
together a useful high voltage, low current power
supply.  Let me know how it goes.

Best Regards,

Greg
www.angelfire-dot-com/ga3/tesla

--- Tesla list <tesla-at-pupman-dot-com> wrote:
> Original poster: Hhchicken1-at-aol-dot-com 
> 
> Hello list!
> My MOT has three windings on it - one for 240v
> mains, one HV winding and also 
> one with about 10 turns which I assume to be low
> voltage, but extremely high 
> current - filament for magnetron?
> If I plugged 240vac into this third winding, and
> drew HV out from either the 
> primary or HV secondary, do you think the MOT would
> fry?  If not, this would 
> presumably give a very high voltage and low current
> output, which is 
> considerably safer than the 2000V, ~1A output given
> in its usual 
> configuration.
> 
> Thanks in advance for any advice,
>     Henry Hall
> 
> 
> 


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