MOT question

I just salvaged a transformer from a microwave and have a question about the secondary windings . This one has 2 , one apparently a low voltage
since it has relatively few windings <abt 6-10 , can't really tell> of 16 or 18 guage wire . The other a high voltage winding of abt 28-30 guage or so . The low voltage winding I can check with my voltmeter , but the HV winding I'm a bit leery of . I'm not a big fan of getting electrocuted , and wonder if someone has any idea of the voltage this winding might produce . I'm pretty sure it's not in the KV range , but even a few hundred can totally ruin your day ...
--
Snag



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On 12/27/2014 8:25 PM, Terry Coombs wrote:

Ya, it could easily be 1000v. A google search is needed. ISTR they stick a voltage doubler on it and run around 2200Volts.
Mikek
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On 12/27/2014 9:36 PM, amdx wrote:

I also remember 2000v, but I don't remember if that's before or after the doubler. Either way, it's serious.
If you have a variac, put 5v on the primary & that should give 40 or 80v or so on the secondary. If you really want to know.
Bob
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On 12/27/2014 8:36 PM, amdx wrote:

I was wrong, it's about 2000 volts out.

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amdx wrote:

I don't think I'm going to be plugging it in ... I'm not equipped to deal with those voltages safely . As I said in my reply to Don , I'm surprised it's that high , they used plain stranded wire for output hookup wiring .
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wrote:

I had a transformer out od a very early B/W TV set as a kid. It had all kinds of windings on it, from 1.5 volts IIRC to about 5000 volts. The 5000 volts was at quite low current to drive the CRT. (Colout TVs went up over 25000 volts)
I went for the low voltage winding at one end and got the high voltage one instead - - - - - - - - - I lived. It was a dangerous piece of equipment.
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On Sat, 27 Dec 2014 23:29:35 -0500, snipped-for-privacy@snyder.on.ca wrote:

Yeah, it's a good thing that those teensy little windings let so little current through. The most I've been bit by is 800v from a b/w TV chassis when troubleshooting at Coleman College. It left a bony scar in the meat of my little fingertip for a decade.
Thank Crom for little miracles that we didn't run a crane into a 17-500kv line with hundreds of thousands of amps current possible. Ever read the medical report on a guy who survived one of those? Too gory for words. I'd rather die from that experience, truth be told.
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On Sun, 28 Dec 2014 10:28:11 -0800, Larry Jaques

I know a guy who survived and lost the arm and leg on one side of his body. He's in his early eighties now - artificial arm and leg.
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    [ ... ]

    [ ... ]

    I got 2 KV from a power supply that could recharge a 200 uF bank in 100 mS, so it was a serious zap.
    Enjoy,         DoN.
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wrote:

Yes, that's a little more "real" than my measly 800v source.
I pulled apart two of my 3 spare ovens over the weekend. One had a nice little xfmr, the other a plastic-cored, plastic-spooled coil of 8ga wire and semi-external ferrite rect. bar. I haven't pulled it farther apart to see WTH the thing is, but any secondary winding is hiding. http://diversifycomm.com/projects/
I hope the 3rd has a matching xfmr to the little one.
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On 12/29/2014 9:37 PM, Larry Jaques wrote:

Ahhh ... the latest MO technology: inverters. Just picking one up tells all - the missing 5 lbs of steel and copper is obvious.
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Larry Jaques wrote:

Has anyone tried to modify a ballast from a street lamp? I picked up five of them the other day, when a crew was rebuilding the lights in a parking lot.
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On Wed, 31 Dec 2014 06:06:47 -0500, "Michael A. Terrell"

Negatory here. Are they replacing them with LEDs and drivers?
On the local scene: I pulled the last MOT out of the largest microwave oven and was really surprised. www.diversifycomm.com/projects/MOTbigass.jpg I may not need a pair of these guys after all. I have .8 x .94 holes after getting the secondary winding out of the way. After hacksawing most of the way through the first half, I chiseled the rest plus the other side. It went much more quickly and smoothly. I'll do that to remove xfmr windings in the future. The best chisel turned out to be an old SnatchOn gasket scraper. <g>
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On 12/31/2014 09:20 AM, Larry Jaques wrote:

I can't really tell from the picture, but it looks like one of the nice ones I used to pull from the old faux-woodgrain ovens. The biggest ones I ever harvested, two of them, were from old Sharp ovens, with a mechanical bell and an analog timer. The trannies from those ovens had laminations that were bolted together, instead of just having a weld seam to hold them together. Big beefy suckers, and heavy as hell.
Jon
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    The low voltage part is to power the filament in the Klystron.
    I would not be surprised if the HV side gets to 1KV or more, frankly.
    You can safely use an ohmmeter on it, as long as you aren't powering the primary.
    But why do you *care* about the secondaries. If you are going to make a spot welder using it, you cut off the secondaries, and wind a few turns of very heavy wire -- or even copper strap with insulation between layers. You need *current*, not *voltage* for spot welding.
    Good Luck,         DoN.
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DoN. Nichols wrote:

I have an inverter TIG machine that also does spot welds , or would if I had the clamp fixture . I have no real plans for this MOT , but couldn't let it go to the dump . I was mostly wondering if I was going to fry myself if I powered this thing up . I'm surprised the voltage is that high , they used plain stranded wire for the output leads . Obviously , I know very little about microwaves - but that can be fixed .
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On Saturday, December 27, 2014 10:58:00 PM UTC-5, Terry Coombs wrote:

If you remove the secondary winding , you can put a new secondary on using 10 or larger wire and have a fairly high current low voltage transformer. This can be used to keep an exposed water pipe from freezing, or to apply a little heat to a water bowl for the animals.
Dan
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On Sun, 28 Dec 2014 17:51:22 -0800 (PST), " snipped-for-privacy@krl.org"

I pulled one of those things out of a microwave once, and was startled to see that the laminations were welded together in a strip.
What's up with that? I would have thought that the eddy currents would be ferocious.
--
Ed Huntress

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On 12/28/2014 8:05 PM, Ed Huntress wrote:

The strip type of laminations were very very high current. Some are in the 10's of Amps with surges 100 Times.
Eddy currents depends on the alloy. I agree on the concept. I suspect they were nominal to the real current.
The big 100 amp windings on soldering guns - where the posts that come to the copper point are part of the winding like the copper point. It suffers more from heat from the eddy and main current so the whole gun heats up. But works for spot solders nicely.
Also tends to demagnetize if something is passed between the loop.
(Can make the solder a larger loop of 10 ga. copper - plastic on - for that.)
Martin
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I don't visualize this, but can imagine how it would work. Silicon steel has a fairly high resistivity, so if the eddy current paths are long enough, the losses could be reasonable.
Joe Gwinn
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