VGA Monitor Cable

Don't ask me why, but I need to build a 1" VGA monitor cable to connect a
very small motherboard to a fairly small LCD screen. The distance between
the motherboard and the monitor VGA connectors is around ½ "

My fist thought was to go out, get the connectors and some cables and solder
a cable form pin 1 to pin 1, 2 to 2, 3 to 3 etc. but before I even got to
that part I notice that my current VGA cables have some kind of cylinder
component right before both ends of the VGA connectors.
http://www.l-com.com/jump.jsp?lGen=...=35&iSubCat=120&iSubSubCat=121&iProductID=201


What are these ugly things??? Even a more stupid question, can I just remove
them???

Thank you.

 

Don't ask me why, but I need to build a 1" VGA monitor cable to connect a

A while back I had to put a mini-tower PC in a NEMA box on a machine, and built
a 5" adapter to do just what you're talking about (having the monitor connect
to the back of the NEMA box, and using the adapter to connect the back of the
NEMA box to the PC). No ill effects. Any longer than a few inches, though,
and you'll probably have signal problems.

Good luck.
Chris

 

They're ferrite beads; they serve to reduce transmitted RF interference; and
for the purposes of your 1" long cable, you can remove them.

(Of course, if you are manufacturing and selling this device, you'll have to
subject yourself to EMI testing either way.)

 

I found ancient runes from Cliff[] in the floor of
sci.electronics.design:

They're ferrite beads to avoid RF problems. For a very small cable, they're not
needed.

 

They're ferrite beads; they serve to reduce transmitted RF interference;
and

Got it, but I am still kind of confused on why some other long cables such
as Ethernet cables that soemtimes are 50 times longer than a VGA cable do
not have ferrite beads??? Aren't this cables acting like antennas too?



Just curios.

 

Ethernet (and its current variants such as 100Base/T) was designed as a
transmission standard. So, signal rise and fall times and cable
construction are controlled to minimize unintended radiation or reception.
For instance, twisted pairs, in which current flowing one way tends to
cancel current flowing the other way.

VGA cables are just a bunch of wires, carrying very-high-frequency signals.
RFI galore.

Eventually things will probably switch to some other means of communication
between the bus, video card, and monitor - like, and I'm just speculating,
serial ATA from bus to card, with the card built into the monitor rather
than into the PC.

 

Right now there is DVI, which is differential, like Ethernet is.

 

Ethernet uses differential signalling over twisted pair cable, which helps
a lot. In addition, the transmit side is usually passed through a common
mode choke and isolation transformer on the board of origin. The common
mode choke in ethernet serves the same purpose as the ferrite on the VGA
cable. All of this together helps tremendously, both with Electromagnetic
Compliance (EMC) and suseptibility to EM Interference (EMI).

Mac
--

 

I found ancient runes from Cliff[] in the floor of
sci.electronics.design:

Because the Ethernet cables have a standard. With controlled signal
rise/falltimes. Ex. Twisted pairs.

VGA cables are just a lot of wires carrying very high-frequency signals.
RFI anyone?