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RE: MOT Voltage Doubler



Dear List,

I'm amazed at the interest this simple posting has generated.  As long as
I'm stirring the pot, I might as well throw in my own 2 pence worth.  For
one thing, I'm puzzled by the huge disparity in MOT outputs.  I've measured
a few US-type MOTs from Litton, Sharp, JC Penny, and Hitachi ovens with a
Fluke DMM (and the optional 1:1000 HV probe!), and they all put out exactly
what they advertised.  The smallest one put out 1890VAC-at-285ma, and the
largest 2250VAC-at-385ma.  I measured the output current just like an NST, by
shorting out the secondary with a DMM set on AC AMPS.  The shunts worked
perfectly--no smoke, no popped breakers, no damage to meter.

The point I was trying to make about the voltage doubler circuit is that if
it only raises the voltage to 2.8 x RMS, then there's little point in
including it in a TC power supply.  Consider the case of two identical
2200VAC MOTs with their cores shorted together and grounded, their
secondaries in series, and primaries reverse-phased.  The two MOTs will
develop 4400VAC as measured across the two HV output terminals.  4400VAC x
2.8 = 12320V peak-to-peak.  Now, if we include tho two voltage doublers, we
get roughly 12320VDC pulsed (2200 x 2.8) + (2200 x 2.8).  If a TC is being
fired by 12320V, does it matter that much if it's AC or pulsed DC?

Thanks for all the inputs.

Greg