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j riv
Posted 2011-01-17T09:59:12.277
Reputation: 2 162
What is the bigger cylindrical part found at the end of USB cables but also some laptop PSU cables?
Answers
15
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.
Fake Name
Posted 2011-01-17T09:59:12.277
Reputation: 2 134
6
It could be a recording device disguised as a USB cable.
Greg Hewgill
Posted 2011-01-17T09:59:12.277
Reputation: 5 099
2
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
Tog
Posted 2011-01-17T09:59:12.277
Reputation: 4 747
Why is high frequency noise a problem on a laptop power cable? – jwg – 2014-05-15T09:26:16.940
1@jwg - Because laptops are excellent sources of it! It's actually more to prevent the laptop radiating electromagnetic noise then receiving it. – Fake Name – 2014-05-15T09:48:24.487