Ferrite beads for noise suppression

[FlimsyFeet]

I have a few of these (http://en.wikipedia.org/wiki/Ferrite_bead) things knocking around. They are designed to suppress high frequency noise from electromagnetic interference.

Would they be of any benefit of putting one somewhere in an analogue video capture chain?

[mike20021969]

I always thought them as gimmicky. Personally, I cant tell any difference with or without them on cables.

Some cables come with them, and other identical cables for the same purpose without.
Go figure :rolleyes:

[IanB]

They reduce interference propagating from one piece of equipment to the next via the shield of the cables. They should not effect the actual signal travelling in the cable.

They allow retrospective correction of bad initial design, i.e. in a perfect world you should not need them.

[Ghitulescu]

They should not effect the actual signal travelling in the cable.

They allow retrospective correction of bad initial design, i.e. in a perfect world you should not need them.

In a cable whose shield serves as mass too they will filter the signal too :) That's why pro cables, where the shield differs from the signal mass/sink, don't have ferrites nor need any.

[hello_hello]

In a cable whose shield serves as mass too they will filter the signal too

To believe or not to believe, that is the question.....

[IanB]

The ferrite beads are to stop common mode signals travelling along all the conductors in the cable, i.e. earth loop type currents and antenna radiation problems.

Ideally they should not effect the signal travelling up and back the cable as the up and back currents cancel and you get no effective inductance. In practise the up and back currents are not exactly matched and you get inductance effects on the small imbalance current.

For the noise current all the signal travels up the cable in the same direction in all the wires, thus you get effective inductance acting on the noise current.

They really have nothing to do with the quality of the cable per se, it is more to do with the hash noise coming out of the socket on a device and preventing in from spreading.