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What is that cylinder on cables?
What's this part?
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3 Answers
It is a Ferrite Bead.
They're used to reduce and dissipate high frequency noise.
To prevent it from moving on the cable, it is overmoulded with plastic.
Functionally, it is a dissipative low-pass filter. It's basically an inductor with very high reluctance, so the magnetic field which it forms get dissipated as heat, rather than reflected back on the cable.
answered Jan 17, 2011 at 10:12
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1@jwg - Because laptops are excellent sources of it! It's actually more to prevent the laptop radiating electromagnetic noise then receiving it. May 15, 2014 at 9:48
It could be a recording device disguised as a USB cable.
answered Jan 17, 2011 at 10:15
The device in your picture is most likely a ferrite ring and is used to reduce RF interference. You'll also see them on a lot of video cables.
You can also buy them as a separate item
Have a look here
