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Playing with transformers.
#31
if you do a 1 to 4 winding, you'll get a 4x reduction in output voltage. The waveform will remain the same.

You can also go for a 2 to 8, or what ever ratio you want. You don't have to do something like a 100 primary with 400 secondary to get the ratio. You are only reading measurements, not creating a load.

Just remember to use those numbers for you calcs based on the oscilloscope output. If the primary is 110V, with a winding of 1 to 4, then the secondary "should" be 27.5V
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#32
You mean like a third temporary coil? It's pretty tight, but I might be able to fit one in there.
-Mike G
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#33
Nah, a second transformer. To test the output waveform of your big transformer, make a second one to reduce the voltage a little bit so you can use your oscilloscope. The other option is to use a resistor ladder, though I don't know how that would effect the waveform.
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#34
Redpacket Wrote:The ~200W loss in the transformer is much more serious. You'll need to treat it as faulty until resolved.... I suspect you have a shorted winding somewhere.

That's perfectly normal with larger transformers that are cheaper built (I.E. Microwave oven transformers). Especially if the E-I plates are stacked as common blocks rather than alternating directions (though the heat loss isn't from that, not to that degree, it's just symptomatic of cheaply build transformers).

Generally the solution is more turns on the primary.

More turns on the primary means you'll need more turns on the secondary to make the same voltage ratio. So now you need a bunch of extra wire in there.

But you can't thin out the wires or they'll overheat. So how do you fit more turns into the same cross-sectional area?

You can't. You have to use a larger transformer core.

That process in reverse is how you end up with microwave oven transformers:

"Copper and steel cost money. What if we remove turns from the primary and secondary? We can use a smaller core and less wire! That'll be cheaper!"
"Yes but it'll have hundreds of watts of waste heat and need a fan running constantly to keep it cool"
"I'm sorry I can't hear you over the sound of how much cheaper it'll be!"
"But the waste energy is going to cost more money in the long term!"
"Yes but it won't cost us money, it'll cost to buyer money. And save us money!"

...

Seems like you're a bit past it now, but if you want some tutorials on larger transformer salvaging and repurposing, I filmed some tutorials on it years ago:





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