Boy, do I feel stupid!

Rich Grise · 2006-01-17T00:08:38+00:00

I've been poking around with a salvated microwave oven transformer (MOT),and doing little diddly simple experiments:And the 0.1 ohm resistor in series with the primary seems to be droppingabout .145 volts, +/- .4; that's an amp and a half! At 115 volts, that's over 150 watts!But nothing got even warm. It was humming merrily at 60 Hz, but it nevereven got above room temperature. So, where are these 150 watts going?Then, finally, after all of these years of dabbling in things electronical,it hit me - that amp and a half is going through _an inductor_!!! With aDC resistance of 1.0 ohms +/- 0.1 ohm. That's one and a half watts of real power. DUH!!!!!Next, I'm gonna see what happens when I take the magnetic shunts out; anyone ever done this, and is it a good idea?[the penny is only for scale, but I did have this wild-ass idea that theinduced eddy currents would make magnetic effects that would be physicallyobservable, but no such luck. )-; ]And at only 1.4 amps, is it worth the bother to wind more primary turns?And are there other newsgroups that might want to participate in a MOTsaga? ;-)Thanks,Rich

Jan 17, 2006 21 Replies

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ehsjr 20 years ago

Ohhh - my bad. I meant what voltage & current do you expect? I dunno if you're going for an isolation transformer, a 12 v at 20 amps or ???

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Rich Grise 20 years ago

Oh, that. I haven't decided anything yet - heck, it could sit there on the bench for months just the way it is befor I feel like dicking around with it some more; it's more a diversion than anything else.

But the idea of a 12V, 20A supply does sound attractive; or maybe

3 windings, and make a +12, -12, +5 supply, or maybe even those new low voltages that chips seem to be using these days. IOW, I can do whatever I want to do with it, I just don't know what I want yet. :-)

Thanks! Rich

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