Ferrite Bead

Ferrite Bead(en.wikipedia.org)

25 points by DevOfNull 3 years ago | 12 comments

sebazzz 3 years ago |

I have something weird with my Edifier speakers. Maybe a ferrite bead can resolve my issues.

I have my setup as follows:

    Lenovo P1 --[hdmi]--> Samsung monitor  ---[3.5mm]----> Edifier speakers
    Desktop computer with Creative Soundcard --> [3.5mm] --> Edifier speakers
                         --[displayport]---> Samsung monitor

I don't have any noise or scratching when I work on my Lenovo. I don't have any noise or scratching when I work on my desktop without having the connection from Samsung monitor to speakers connected. However, when I have everything connected I get a slight noise and scratching sound which gets more pronounced when I start to load my GPU more, for instance when running a game.

At first I thought this was a ground loop, but the noise isn't constant, and isn't directly coming from my computer or sound card but indirectly via the Samsung monitor when I start to game and my computer draws more power.

jareklupinski 3 years ago | |

Interesting, I have a similar issue when I work with CAD models. If I rotate a particular model in a certain way, I can almost hear a 'scratching' noise coming from my GPU as the frames draw. If the GPU is already loaded, it seems like the noise escapes to my powered sound monitors? I think it is some sort of 01010101 color rowhammering the memory at 144Hz...

mistyvales 3 years ago | |

Coil whine?

sebazzz 3 years ago | | |

Can't be, as the noise isn't coming from my computer.

woleium 3 years ago |

I've been wondering if one of these would solve folks Ikea chair problems (where the piston causes emf sufficient to make some monitors loose signal)

n2d4 3 years ago | |

For those who missed the discussion: https://news.ycombinator.com/item?id=35742476

shrimp_emoji 3 years ago | |

Haha, my (I think damaged) MSI monitor gets that when I shift in my chair sometimes!

aaronax 3 years ago |

These seem to have become much less common. I'm guessing better filtering in devices themselves and possibly better cable construction?

jareklupinski 3 years ago | |

From https://www.ti.com/sc/docs/apps/msp/intrface/usb/emitest.pdf :

> If a single ferrite bead is used it is not usually necessary to also have the separate beads as shown in Figure 8

Yup, it's probably cheaper to put a few small ferrite beads on the board than to put a big one on the cable.

Being a differential signal, I never understood why USB cables would _need_ them, but seeing it on a premium cable inspires the feeling that you bought a better product? I also think reduced 900MHz interference from cordless phones (remember those?) made homes quiet enough that the bead became more of a value-add for most applications. Just guessing...

mistyvales 3 years ago |

Oops, just removed one of these from an old Logitech mouse because it made it hard to plug into my 1040ST..

mobb_solo 3 years ago |

Can anyone explain the noticable symptoms of interference or radiating, in situations where usb is not filtered?

jareklupinski 3 years ago | |

Anecdotal, but back when I was playing with spark gaps, my housemate's USB game controller would disconnect from the host every time I shot a spark. It would refuse to reconnect until they unplugged and replugged the cable back in. They switched to a better cable (with a bead), and it stopped happening.

Lenovo P1 --[hdmi]--> Samsung monitor ---[3.5mm]----> Edifier speakers Desktop computer with Creative Soundcard --> [3.5mm] --> Edifier speakers --[displayport]---> Samsung monitor