PT laminations are usable as OT laminations ?

[kagliostro]

I've a pair of large unknown transformers (in very good shape), may be 250-350W

probably they were recovered from a pair of inverter supply (but I'm not sure 100% about that)

plus I've other old PT in bad shape (about this I think they must be rewound to be used)

the  question is:

are the lamination of this big transformers reusable as to wind large OT (250-350W) for bass and/or guitar use ?

Thanks

Kagliostro

[HotBluePlates]

The laminations themselves? Probably.

You should consult the person doing the rewind.

[kagliostro]

Ciao HBP

a friend that has some experience in transformer building told me that if the lamination are till 0.35mm thick they can be used for OT, instead lamination of 0.5mm aren't so good to be used

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I've read that is important if the lamination has <oriented silicium grains> (not sure if this is the correct translation for the italian <granuli di silicio orientati>) and this a very important quality of laminations.

K

[HotBluePlates]

Transformer building is maybe too do-it-yourself for my ability. I have very little knowledge about the great many considerations that must be balanced.

I find it very believable that output transformers require different build trade-offs than power transformers.

I think your friend's knowledge, even if limited, will exceed mine. I'd follow his recommendations. I know that the Radiotron Designer's Handbook has a large section on transformer building/winding. However, it is a complicated process and the short-cut methods for designing the transformer may not be easily understood from the RDH write-up.

This is a whole field of specialization with at least as much to learn as design of the rest of the amplifier.

[kagliostro]

My interest is about PP OT

may be mounting all the "E" lamination on the same side and "I" on the other side, there are chances for an SE OT

K

[HotBluePlates]

I believe P/Ts design are optimized for 50/60Hz feed, and O/T design is for a broad range of frequencies.

Yep, that's typical.

Might be less of an issue if a complete rewind is being done, but this would be a (at least minor) difficulty if you try to repurpose a power transformer as an output transformer with no modifications.