fat round things in cords?

February 19, 2009 3:22 AM

what are the fat round things sometimes found inline on various types of electronic cords?

some USB chords have them, printer cords, power supply cords, many don't. what do they do? what if your replacement power supply doesn't have one? (try googling this question- you get nowhere)

posted by karl88 to Technology (10 answers total)

They're toroids, meant to filter out interference that would otherwise mess up your electronic device.
posted by dunkadunc at 3:26 AM on February 19, 2009

Another term for it is a 'choke'.
posted by dunkadunc at 3:38 AM on February 19, 2009

Best answer: both of the above are correct, but they are usually called ferrite beads.
posted by sergeant sandwich at 3:54 AM on February 19, 2009

(try googling this question- you get nowhere)

Sorry, I couldn't resist: my first query attempt.
posted by knave at 4:05 AM on February 19, 2009

Ferrite beads
posted by pompomtom at 4:07 AM on February 19, 2009

A popular question.
posted by spikeleemajortomdickandharryconnickjrmints at 4:35 AM on February 19, 2009

Also called a balun (short for balanced/unbalanced).
posted by echo target at 6:51 AM on February 19, 2009

Could I have been the first person to ask about this on AskMe?
posted by Faint of Butt at 9:02 AM on February 19, 2009

It's not a balun when it's on a cable like that. It's a common mode choke.
posted by low affect at 11:16 AM on February 19, 2009

Response by poster: doh! i didn't use "cylinder" in my googling, else i would have found it like knave did. i used "round", the trick is all in the question.
posted by karl88 at 3:06 AM on February 23, 2009