Monitor cables

  Barrykneeshaw 02:12 25 Jan 2003

I am a comparably new to IT Support user who has been put into a junior IT support position which will duly be supported by numerous training packages.
I have been asked what purpose the "bulb" type unit on the monitor to PC cable serves.
I have NO idea.
Can anybody assist?

  jazzypop 07:58 25 Jan 2003

Simple answer - click here

Search Google for 'video cable shielding' (or try combinations of this with ferrite), and you will find far more technical answers.

  Gongoozler 08:01 25 Jan 2003

The device is a choke to prevent common mode high frequency from one piece of equipment getting to the other equipment. The way it works is like this. If there is a genuine high frequency signal, it will flow out of one wire (typically the signal wire) and return via another wire (typically a ground or signal negative). The result is that there is no net current (one cancels out the other), so the choke will have no effect. If, on the other hand, there is an earth difference, due perhaps to a noisy switch mode power supply in one of the pieces of equipment, then there may be a current in the earth wire from one equipment to the other. This current would not be cancelled out by a returning current in another wire - it may even be added to by a current in the same direction. In this case there would be a net current through the choke, and so the choke would attenuate it. These common mode chokes are very useful in that they significantly reduce common mode current while having no effect on the signal.

  BRYNIT 10:00 25 Jan 2003

Its to help prevent interference from electrical close cables.

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