O and I transformer LAMS?

[Cobaltblue]

It might be my dodgy eye sight but I have a transformer and can't see the usual E and I lams.

The outer "ring" seems unbroken

I cannot recall coming across such a construction, the closest is the C core transformers.

Its hard to see because of the varnish but I have concluded that the centre leg is the join.

You can't see the join because there are SRBP "shims" to hold the bobbin in place while it was varnished.

I am sure someone can put my mind at rest!

Cheers

Mike T

[Leon Crampin]

The outer ring is unbroken. The centre "I" has a break where it joins the "O" at the edge of the bobbin. To get the transformer apart, lift up the edge of the "O" where the break is, and slide the lamination out. The next lam has the break at the other end of the bobbin.

Nearly all German transformers are made this way - higher scrap, but only 1 air gap per lam set, so more efficient.

Leon.

[turretslug]

I've occasionally seen this lamination format with German-made transformers- they look to be in the form of a square "8" with the cut at one edge of the centre bar, this presumably being fed into the bobbin under bending of the outer perimeter, finally springing back flat when fully over the end-pieces and stacked alternately. I can only assume that minimisation of magnetic circuit interruption gives a slight efficiency gain?

Crossed with Leon! Colin

[Radio Wrangler]

Once vacuum impregnated, they do not come apart easily. The lams are not likely to be re-useable. If it needs re-winding, you may be better off looking for another transformer.

David

[Cobaltblue]

Thanks for the replies
As soon as I started reading Leon's description I recalled coming across this decades ago I have virtually no ( post war) Continental sets in my collection.
I remember how frustrating it was to get apart (I was still in my teens and wanted the wire for some hair brained project).
The transformer is not a part of any set just one of several obtained from Giveawayguy so is available FOC if its of use to anyone.

I will start a separate post when I get a mo

Cheers

Mike T

[short wave]

I posted a thread here about unusual lams i found

https://www.vintage-radio.net/forum/...d.php?t=103450

[Refugee]

I have seen them as "T" and "C" shaped in the distant past.

[Ed_Dinning]

Hi Mike, I have successfully rewound this type of transformer/ lam, but if heavily varnish impregnated they mat be vet difficult to separate. Popular style in German/ French sets of the 30's

[retailer]

I'm with Ed Dining on this one - rather than rewound I salvaged a similar core and bobbin and wound a transformer with new specs, see post here

https://www.vintage-radio.net/forum/...d.php?t=153518

The bobbins was made up of stampings using a bakelite type material - the stampings lock together like a puzzle toy, it is quite clever.

I have since found that some refer to the core as an M core, getting the lams apart was not that hard (with the help of some MEK) but you need to be careful not to damage the bobbin stampings.

[Cobaltblue]

As mentioned in post #5 not going to rewind it, it's not faulty and not part of any of my collection its just a random transformer.

I ran it for an hour on 240V it stayed cool and output was just under 8V unloaded dropped by 200mV when loaded with 10 Ohms

The link to the construction is interesting though.

Cheers

Mike T