What is this copper surface used for in this SMPS transformer?


How I see it is wide in the comparation to the rest of other copper wires gauges in this transformer.

It is enamel insulated like other magnetic wires in this transformer.

What is this used for.

It is connected to the pin?

 

Primary to secondary shielding, connected to earth GND.

 

That copper strip is EITHER a shield, as Max offers, OR it may be a secondary winding. I have seen copper and also aluminum strip used in transformers.

 

With one pin connection I vote for the grounded shield.

 

OK,and certainly with a single connection that would be the case. When I built a tape-wound transformer the two connections were separated by many layers, since it was one turn per layer.
So I suggest, before the TS does any more disassembly, using an ohm meter to check for continuity with another pin. It could be a compact higher current transformer.

Also, why would an inter-winding shield be on the outside of a transformer??

 

Normally I put them in between the primary and secondary.
It could be on the outside for shielding.
It probably has only one wire connected.

 

Usually, if a transformer is to be totally shielded, that is done with the steel shells. Primary from secondary shielding is only efffective between the primary and secondary, like most other shielding, to isolate the source from the receiver.
But, as I inspected the photo again, I see that quite a bit has been unwound from the transformer spool already, and a lot of the strip is exposed, enough for quite a few turns around the bobbin. Is there a

 

I intend to make 12V/1A SMPS power supply. Do I need it in that small transformer?
https://forum.allaboutcircuits.com/threads/12v-1amp-smps-circuit-how-to-make-it-as-regulated.209512/

 

Do I need it in that small transformer?

No, if you are making this just for you. If this is for medical equipment then yes.