Quote:
Originally posted by Czilla9000
Demolition, I have abandoned the idea of a permanent magnet.
So in other words, the more a material responds to a magnetic field, the better it is as a choke? |
Yes, that's basically the idea. However, to be more precise, the permeability of a choke determines which frequencies it is better at filtering. So, for example, if you have a specialized application that requires exactly 145 ohms of impedance and an attenuation of 7.5 dB in your cables to target and filter certain frequencies, then you could conceivably find ferrites that will do that.
Anyway, before I launch into another Physics lecture, I think that for most purposes that we will run into, almost any ferrite choke will do the job as long as it fits on the cable.
A popular one is from
Radio Shack. I've bought snap-on ferrites like
this one from Digikey, as well. I use them on power cords and on cables around my computer (such as the ones leading to multimedia speakers). As mentioned above, the idea is to attentuate high frequencies which often manifest as noise. There's a lot of stray EMI/RFI around power supplies and computers, so ferrites help here.
I've also heard that they work well on headphone cables to prevent them from picking up stray RF. On the other hand, I've also heard that they dull the highs. I haven't used a ferrite on a headphone cable since I haven't had a problem that might require one. Maybe someone with experience in that regard could chime in on that?
D.