I've scrapped some components lately and I put aside some special ones that Im undecided to throw then away or to keep. They look important. From what I can say, that black cilindrical 'case' is made from Ferite (not plastic) and inside is a coil with 4 wires coming out. Could be some sort of transformer? What these are ? What was their (possible) use?

Thank you !

 

Toroidal transformers. med and high freq.

 

Toroidal transformers. med and high freq.

Thanks, and they are usually used in ? What device? What circuit?

 

Try to google this "pot cores".

 

Excellent answers ! I start to get it. This Pot Core will concentrate or retain more inductance than a Toroid Core, thus it is more efficient. Mainly used in receiving or transmitting fv like audio amplifiers or radio stations. I hope I got it right.
What I have here is scrapped from a very old board, probably from 1980-90.
Thank you both !

 

I find this guy who is explaining it excellent :

 

Years ago, I wound an audio output transformer for my crystal radio using a 47 mm diameter, Siemens N22 pot core set.



It's an autotransformer with 500 turns of 30 SWG enamelled copper wire for the input with output taps at 50 turns and 100 turns.

The 50 turn tap is for the existing 3 Ω speaker and the 100 turn one a provision for speakers of higher impedance.



Nandu.

 

Excel

Years ago, I wound an audio output transformer for my crystal radio using a 47 mm diameter, Siemens N22 pot core set

Excellent ! Thank you !