Whats the thing on the wire ??

hi,
i have noticed that several cables especially the ones used for
communication, have a bulb like thing inbetween the wire. what is it
used for ? i have it on the cable that i use for connecting MP3 player
to PC. it is also there on the moitor cable. is this some sort of an
amplifier or overvoltage protector or maybe some sort of spying
device!!
TY
Braz -in -go

 

[Bob Myers]

<brazingo@gmail.com> wrote in message
news:1123879682.649835.170600@g47g2000cwa.googlegroups.com...

hi,
i have noticed that several cables especially the ones used for
communication, have a bulb like thing inbetween the wire. what is it
used for ? i have it on the cable that i use for connecting MP3 player
to PC. it is also there on the moitor cable. is this some sort of an
amplifier or overvoltage protector or maybe some sort of spying
device!!

Generally, what you're describing is a toroidal ferrite "core" which
has been placed around the cable (and then covered by the
overmolding of the connector or an outer jacket placed over the
cable assembly), and is intended for EMI (electro-magnetic
interference) suppression.

Spying device? You have got to be kidding....I hope...

Bob M.

 

[Rheilly Phoull]

One day Bob Myers got dressed and committed to text

brazingo@gmail.com> wrote in message
news:1123879682.649835.170600@g47g2000cwa.googlegroups.com...
hi,
i have noticed that several cables especially the ones used for
communication, have a bulb like thing inbetween the wire. what is it
used for ? i have it on the cable that i use for connecting MP3
player to PC. it is also there on the moitor cable. is this some
sort of an amplifier or overvoltage protector or maybe some sort of
spying device!!

Generally, what you're describing is a toroidal ferrite "core" which
has been placed around the cable (and then covered by the
overmolding of the connector or an outer jacket placed over the
cable assembly), and is intended for EMI (electro-magnetic
interference) suppression.

Spying device? You have got to be kidding....I hope...

Bob M.

Hmmm, that said it wouldnt be a bad spot for such a device!! The average
person is now used to seeing the ferrites.

--
Regards ..... Rheilly Phoull

 

[Rodney]

<brazingo@gmail.com> wrote in message
news:1123879682.649835.170600@g47g2000cwa.googlegroups.com...

hi,
i have noticed that several cables especially the ones used for
communication, have a bulb like thing inbetween the wire. what is it
used for ? i have it on the cable that i use for connecting MP3 player
to PC. it is also there on the moitor cable. is this some sort of an
amplifier or overvoltage protector or maybe some sort of spying
device!!
TY
Braz -in -go

It's used for noise suppression. Gives you a cleaner signal.

 

[John Popelish]

brazingo@gmail.com wrote:

hi,
i have noticed that several cables especially the ones used for
communication, have a bulb like thing inbetween the wire. what is it
used for ? i have it on the cable that i use for connecting MP3 player
to PC. it is also there on the moitor cable. is this some sort of an
amplifier or overvoltage protector or maybe some sort of spying
device!!

It is a form of common mode inductor that suppresses radiated noise.
It is made of permeable (allows a magnetic field through, much better
than air does) ferrite. The cable passing through makes this into a
transformer with as many 1 turn coils as there are conductors in the
cable. The transformer is essentially invisible to any currents that
pass both ways through the cable (in one conductor and back through
another one), since their magnetic fields cancel. But any current
that is trying to pass back and forth through the hole, in only 1
direction at a time, has to pass through the inductance of a 1 turn
coil through that amount of core. This impedance in series with these
common mode currents reduces their magnitude, and also reduces the
efficiency that a resonance can take place as a wave bounces up and
down the wire, making the cable a less effective antenna. The exact
location of the core on the wire can make a bog difference what
frequencies are most effectively suppressed, so once testing
determines the best place for the core (standing waves tend to produce
current nodes and peaks at different places), it is often held at the
correct place with a plastic overmold.

 

[Kitchen Man]

On 12 Aug 2005 13:48:02 -0700, brazingo@gmail.com wrote:

...maybe some sort of spying device!!

Yes!! It is a packet-sniffer, and is forwarding all your porn to the
FBI!!!!!

Or not.

 

[Bob Myers]

"Rodney" <rdavies@okanagan.net> wrote in message
news:11fqv6c69vbsm4e@corp.supernews.com...

It's used for noise suppression. Gives you a cleaner signal.

Not really. The presence of a ferrite on these cables
does very, very little to improve the signal quality, and
more likely may result in some slight degradation (no, there
SHOULDN'T be any added inductance appearing in
the signal path, but then in theory, practice is just like
theory - while in practice, of course, it's not...). It's
an EMI suppression device, meaning that it's basically
there to help hold down unwanted radiated emissions.

Bob M.