Weird attachment to AC cord??

MrWackyPants

Posts: 6   +0
What is this thing? It came attached to my camera AC adapter cord. I wasn't sure if it needed to remain on the cord. Looked like it might create a magnet running the cord through the same tunnel a few times. What does it do?
 

Attachments

  • 20201012_225947.jpg
    20201012_225947.jpg
    682.5 KB · Views: 2
It's a clamp-on 'noise filter' - they help to suppress the effects of frequent spikes in the current travelling in the cable. This, in turns, helps to reduce electromagnetic interference.
 
They're needed where any device might exhibit instability, data loss, unexpected behaviour, etc in the presence of electromagnetic interference; they're also needed to help reduce the amount of interference created by the cable itself.

For a simple explanation as to how they work, the object (also known as a ferrite bead) contains two pieces of a ferromagnetic material. If the interference is within a certain range of frequencies, the energy is contains will be 'absorbed' by the material and turned into heat - thus reducing the intensity of the interference. A more technical (and more accurate) description can be read here.

More often than not, they're simply there to meet a country's market regulations, rather than do anything particularly significant. They absolutely shouldn't be used everywhere - even though they're completely passive components, their presence in any circuit will have an impact on how it operates. A poorly chosen filter can make it operate worse.
 
Back