EI-96 transformers of different age. - diyAudio
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Old 19th June 2017, 04:59 PM   #1
Turbon is offline Turbon  Sweden
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Default EI-96 transformers of different age.

Or should the subjekt be "Mix laminates of different permeability"?

Hi, I asked this in Tonys latest as well but it might be of interest for a broader audience.

I have these two donator transformers both EI-96. The seemingly newer one claims to deliver a staggering 400VA and the other one I don't have any information about.
Would measuring the wire diameters give a clue of the VA or are there other aspects to consider? The stack of the newer one is 62mm and 50mm for the other. Both 0,35 mm laminates. Colourwise the newer laminates are much darker and more brittle.

Could I mix laminates if they are of different permeability to even them out? This to make two equal transformers?

Regards

Last edited by Turbon; 19th June 2017 at 05:19 PM.
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Old 19th June 2017, 05:41 PM   #2
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If you can find info of the laminations separately, and or measure them, you can. If and only if, your induction is lower than the lower saturation induction of the composite core. In other case, if one of them becomes saturated, the entire core will saturate, and a powerfull short circuit to the source will result.
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Old 19th June 2017, 05:53 PM   #3
Turbon is offline Turbon  Sweden
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Thanks Osvaldo.

I will then save the better stack for future use and look for another lower grade EI-96 and if fortunate I will stumble over another high grade one

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Old 19th June 2017, 05:58 PM   #4
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10:04.
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Old 19th June 2017, 05:59 PM   #5
Turbon is offline Turbon  Sweden
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Or 10:02

Last edited by Turbon; 19th June 2017 at 06:03 PM.
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Old 19th June 2017, 06:29 PM   #6
JMFahey is offline JMFahey  Argentina
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We audiophiles are pack rats and always find excuses to keep junk, sorry:stuff around for future use

You do not know that one is higher grade than the other, colour or age are not reliable indicators of anything.

You "should" measure them, as Osvaldo indicated, magnetically of course, but I guess that wonŽt happen

Only quickŽn dirty measure which may mean something is sheet thickness.

Typical general purpose iron is around 0.35mm ; cheap cheap one is often up to 0.50mm and some grain oriented type can be made in 0.30 or even 0.25mm , so IŽd suggest you measure them: IF both 0.35mm treat them as general purpose power supply grade and feel free to mix them for that use; if different then donŽt mix, post results here.

Another rough quality indicator is edge quality: good heat treated and high silicon content steel is hard and brittle, and edges are sharply punched, while real cheap iron is softer, "flows" under the tool edge and creates a sharp burr along the edge, easy to feel by touch.

If you sharply bend it back and forth, good steel will crack easily, after a couple movements, and make a particular "sandy" noise; cheap steel will bend back and forth many times, will eventually break but in a different "softer" way and leave behind a quite curved edge.

There is one crude electrical test you can do: calculate and wind primary only in a plastic bobbin, fill it with one kind of iron and plug it into mains; check how warm (hot ??) it gets after, say, 30 minutes; then repeat filling same core with the other one.

Not a direct simple test, but winding just a primary is not that much work ayway.
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Old 19th June 2017, 06:39 PM   #7
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JMFahey - read it again please...

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Old 19th June 2017, 07:59 PM   #8
Eva is offline Eva  Spain
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In terms of magnetizing current: mixing laminates of different materials equals series separate inductors, one made with each material, as long as halves facing are of same material. So one material can saturate first, and later the other, but the volts*seconds/turns product is still the sum of those contributed by each material.

Thickness of laminate controls eddy currents, lower thickness for higher frquency.
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Old 20th June 2017, 09:55 AM   #9
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Quote:
Originally Posted by Eva View Post
Thickness of laminate controls eddy currents, lower thickness for higher frquency.
That's right. But there's a coincidence: Lamination manufacturers use to stamp cheap and simple low-inductance laminations from 0.5 mm sheets, while high quality, high-inductance, low-loss or even GOSS laminations are 0.35 mm or less.

Best regards!
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Old 20th June 2017, 12:08 PM   #10
Turbon is offline Turbon  Sweden
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So Eva and Kay - your view is that I can mix different grade laminates to even the stacks out - the result will be better than the inferior transformer but worse than the better transformer? Is that what you are saying?

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