22 May 2018

You’ve probably noticed those strange cylinders at the end of your puter cables.

It looks a bit like the cable was slightly overzealous at dinnertime and swallowed something a bit too large…

As it happens, those strange meals are actually ferrite cores.

Ferrite is a totally magical material!

So there you have it!

A choke is basically a filter – in this case a low-pass filter – that prevents high-frequency noise from passing along your data cable (or its shielding). This noise is generally related to undesirable radio-frequency transmission or reception by the cable itself.

Note that there are other types of ferrite than just the kind used to make chokes. Other ferrites are used for things such as transformers, inductors, magnets in motors, and all kinds of other cool stuff.

You can grab a 20-piece set of snap-on ferrite cores here.

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Ferrite: Those magic thingies at the end of your cables
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2 thoughts on “Ferrite: Those magic thingies at the end of your cables

  • 23 May 2018 at 02:26

    I have computer laptop which cables do not have that thingie, could one can take one from another -that is not useful anymore- and put it? propotionally as seen in the video?

    • 23 May 2018 at 11:39

      Well, not all cables need one. They’re usually added for passing EMI testing (to ensure Gizmo A doesn’t interfere with Gizmo B via radio waves, more or less). Of course, it can’t really hurt anything to stick some of the snap-on ferrite cores on your cable if you’re seeing weird problems. I’ve done it before.

      For example, some USB cables are very cheap for a reason, so a ferrite core might help. Other USB cables are very well designed, so the ferrite is unnecessary. It also depends on what the USB cable is connecting! Ultimately, you’d need some fancy equipment to do some testing to really know for sure if a ferrite choke would help or not.

      One popular use is if you have computer speakers, and you can hear those fun “computer noises” when a cell phone is near the speakers. Many people have reported winding the audio cable from the puter to the speakers around a ferrite core, and poof! No more weird noises. Haven’t tried that one myself – yet!


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