Re: MOT power supply

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

Original poster: "Gregory Hunter by way of Terry Fritz <twftesla-at-qwest-dot-net>" <ghunter31014-at-yahoo-dot-com>

You should not assume that a 120vac MOT will work at
240vac, because it won't. The higher voltage won't
hurt the MOT--it's just that the circuit breaker will
trip immediately. The 240v will cause the 120v MOT to
saturate, and it will behave like a short circuit.
This will probably trip the circuit breaker so quickly
that the MOT will not be harmed. However, you can use
two 120vac MOTs with 240vac if you place their
primaries in series. In this arrangement, the 240v
divides between the two primaries, so each primary
only "feels" 120v. Naturally, this works best with two
identical MOTs.

The only way I can think of to use a 120v MOT at 240v
is by altering the supply current somehow, because it
just won't work with 60Hz wallplug current. I suppose
it might work if you could increase the frequency
somehow--say up to 120Hz instead of 60Hz--but that's
more trouble than it's worth. Another way is to pulse
the current. A big TRIAC could be used to feed 340v
pulses (from a 240vac outlet) to an appropriately
ballasted 120v MOT. That would give higher output
voltage at some cost to output power. Power TRIACS are
cheap & plentiful, and the elementary RC/DIAC control
circuit is easy to build. The main problem with such
schemes is that the cost and trouble often outweigh
any gain. It's easier to just accept the limitations
of MOTs and use them within those limitations.

Scan the web a bit before you wire up anything. There
are numerous successful MOT power supplies out there
already tested & proven.

Regards,

--- Tesla list <tesla-at-pupman-dot-com> wrote:
 > Original poster: "Mark Rossman by way of Terry Fritz
 > <twftesla-at-qwest-dot-net>" <marossma-at-oakland.edu>
 >
 > Has anyone built an MOT power supple with an imput
 > voltage of 240v  with
 > transformers that came from a 110 volt microwave. Im
 > assuming that the
 > primary windings could easily handle the higher
 > voltage, but i thought id
 > ask before i hooked it up.
 >
 > Thanks a lot
 > Mark
 >
 >


=====
Gregory R. Hunter

http://hot-streamer-dot-com/greg