EI-96 transformers of different age.

[Turbon]

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

 

[Osvaldo de Banfield]

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.

 

[Turbon]

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

Regards

 

[Osvaldo de Banfield]

10:04.

 

[Turbon]

Or 10:02

 

[JMFahey]

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 won´t happen

Only quick´n 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 I´d 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 don´t 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.

 

[Turbon]

JMFahey - read it again please...

Regards

 

[Eva]

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.

 

[Kay Pirinha]

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!

 

[Turbon]

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?

Regards

 

[Turbon]

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 won´t happen

Only quick´n 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 I´d 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 don´t 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.

Sorry that I answered quite bluntly...

Sure they are of different specs - as you wrote the "better" one breaks after one bend and the "inferior" one can take several bends before it gives up. I will also check the other rough test you described.

Thanks a lot

Regards

 

[Kay Pirinha]

I'm not sure, Turbon, 'cause I never did it. But I remember a publication in the then (in the 1960ies) famous German FUNKSCHAU magazine where the then new PM type of laminations were introduced. They said that different steel qualities could easily be mixed within the same transformer.

Best regards!

Edit: This is an answer to #10...

 

[Kay Pirinha]

Too late for another edit:

Actually I'm also in that EI96 thing, 'cause I'm considering to rewind the mediocre (at it's best...) output trannies of two Philips »typewriter« EL 6425 PA (we call it ELA) amplifiers as the as part of a major rework to adress some severe design flaws. Main purpose is to get rid of the output for 10-25-35-50-70-100V lines which, with some degeneration, may suit to 8 and 16 ohms speakers, and have 4-8-16 ohms terminals, to do a more sophisticated winding scheme and to get a high quality core instead of the original one consisting of cheap 0.5mm laminations. Gladly I've found a German lamination manufacturer which may sell EI96 laminations in VM111-35 grade. Minimum quantity will be 1000 pc., though. But the price they announced to me ist still interesting, even for this quantity.

Best regards!

 

[Turbon]

Too late for another edit:

Actually I'm also in that EI96 thing, 'cause I'm considering to rewind the mediocre (at it's best...) output trannies of two Philips »typewriter« EL 6425 PA (we call it ELA) amplifiers as the as part of a major rework to adress some severe design flaws. Main purpose is to get rid of the output for 10-25-35-50-70-100V lines which, with some degeneration, may suit to 8 and 16 ohms speakers, and have 4-8-16 ohms terminals, to do a more sophisticated winding scheme and to get a high quality core instead of the original one consisting of cheap 0.5mm laminations. Gladly I've found a German lamination manufacturer which may sell EI96 laminations in VM111-35 grade. Minimum quantity will be 1000 pc., though. But the price they announced to me ist still interesting, even for this quantity.

Best regards!

Sounds as a perfect contender for a group buy . I'll take half of the stack.

Regards

 

[Kay Pirinha]

The manufacturer told me the weight of 1.000 pc. of M165-35S (aka VM111-35, aka M6X) EI96 laminations, it's 16.1 kg. Of course I may ship half of them to you, once I've got my hands on, but be prepared of some high-ish shipping fees to Sweden. I'm planning a short travel to the factory, which is just about 130 km apart from me, in order to save my own shipping and packaging costs .

Unfortunately I've asked for laminations for both the power and the output trannies, that is EI120 and EI96 laminations. 1.000 pc. of each (i.e. 2.000 pc.) will cost €180 (plus VAT and S/H), so I can't tell you the EI96s' price by now. But you may have got some clue, don't you?.

Best regards!

 

[Elvee]

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

If you use the usual method for transformers of interleaving the laminations (gapless construction), and you alternate the types, you will end up with a core having properties intermediate between the two grades.
If you group them, the result will be less predictable, especially if they are widely different

 

[Kay Pirinha]

Yes, that coincides with the statement in the abovementioned FUNKSCHAU article. But transformer calculation may be some tough stuff for laminations of different qualities within the same core, right?

Best regards!

 

[Elvee]

Not necessarily: if the laminations are homogeneously blended, the characteristics will be intermediate between the two flavors, including Bmax, the most important parameter for transformer design.
At a microscopic level, things will be rather complicated, and some parts will operate in saturation (and not necessarily the ones having the lowest Bsat), but the end result will obey the simple laws, with maybe slightly higher iron losses, which is not a very serious issue for small to medium size 50/60Hz transformers

 

[Turbon]

The manufacturer told me the weight of 1.000 pc. of M165-35S (aka VM111-35, aka M6X) EI96 laminations, it's 16.1 kg. Of course I may ship half of them to you, once I've got my hands on, but be prepared of some high-ish shipping fees to Sweden. I'm planning a short travel to the factory, which is just about 130 km apart from me, in order to save my own shipping and packaging costs .

Unfortunately I've asked for laminations for both the power and the output trannies, that is EI120 and EI96 laminations. 1.000 pc. of each (i.e. 2.000 pc.) will cost €180 (plus VAT and S/H), so I can't tell you the EI96s' price by now. But you may have got some clue, don't you?.

Best regards!

Kay, you don't happen to be close to Köln on the 11'th of July which would be nice if you have recieved the laminations by then . Or more precisely somewhere along the route between Puttgarten and Köln... Actually the EI120'es are more interesting to me.
Shipping as you mentioned will be a rip off

Regards

 

[Turbon]

Not necessarily: if the laminations are homogeneously blended, the characteristics will be intermediate between the two flavors, including Bmax, the most important parameter for transformer design.
At a microscopic level, things will be rather complicated, and some parts will operate in saturation (and not necessarily the ones having the lowest Bsat), but the end result will obey the simple laws, with maybe slightly higher iron losses, which is not a very serious issue for small to medium size 50/60Hz transformers

This is good news and in line with what Eva described about the matter. I will try this in the following way - wind them to my calculated specs - don't mix them and note the temperature after one hour - let them cool to ambient - mix the laminates and note the temperature again after one hour. If no change - they are probably the same grade? Maybe I should load them to 50% during the test?

Flaws in my thinking?

Regards