Jeff Liebermann wrote in message
...
On Tue, 2 Mar 2010 08:40:39 -0000, "N_Cook" wrote:

When such a ferrite cylinder is slid over shielded cable of a laptop
supply
cable, ie one conductor housed within a sheathing and the ferrite around
the
outside of that

Of course they work. No sane manufactory would intentionally design
cables with giant blobs near the ends.

There are multiple flavors of material, composition, size, and shape.
The ferrite clamp on cylinder that I think you're referring to is
usually necesary to prevent the laptop and the switching power supply,
from radiating EMI and RFI. The FCC gets rather irate when that
happens. Everything will work without the ferrite cylinder, but will
not pass Part 15.

http://www.howstuffworks.com/question352.htm


--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

I can see a simple insulated pair of cables fed through and looping around a
few times within a ferrite ring working, but does a cylinder over shielding
work. ?