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My Nikon Usb cable have this. Anyone knows what is it? It's quite typical to have on many USB wire..

LINK

I do not know what it is....I am sure someone will be along shortly who will be able to help you :)

It is a balun used for electrical noise suppression, especially parasitic oscillation. If you open it up you'll find a split, bored cylinder of compressed powdered iron. It's a simple inductor. Or just a bumpy thing. >:o]

Does it interfere the connection, data rate, or anything when I remove the 'balun'?

I don't know. I once replaced an old power suppply in an industrial tool grinder with a new, efficient switching supply and forgot to snap a balun on the lines -- the info on the CRT screen was nearly unreadable until I did. Try it. There is also the distinct possibilty that it is required of the manufacturer to reduce rfi emissions from the device...

Balun's are also needed if you have a video product from one of the Telecom companies such as AT&T or Verizon. It splits the video chanell from the audio/data channels. Without it everything (digital TV, Data, Voice is hopelessly intermingled. I suspect the same is true if you use VOIP from a Cable TV company.

I didn't realize Mike and GBRx3 were so well versed in the electronical things. I am impressed. I thought Balun' was a lot of things but nothing quite that involved. Way to go boys.

I see... it's more like a separator... to separate two different signal. My nikon USB cable has two branches which is the usb and AV cable. Older Canon camera has two separate ports on the camera. Newer canon models has two functions on the same port. Maybe, just to be safe i dont want to remove the balun to see effect. anyway, thanks guys..

I would leave it alone. Baluns can be used for many different applications, both mechanical (as Mike pointed out so well) and for data transfer issues. There is a good, if highly technical, explanation of Baluns here . The bottom line is that when it comes to an AV port, for example if you are trying to send pictures straight from your camera (which is considered a balanced output) to say a coaxial cable (which is considered an unbalanced transmission source) to your TV it converts the signal to a compatible format.

The effect on the data rate should be minimal anyway. Anytime you put something between your output source (camera) and your input source (computer) it is going to affect the rate a bit, because all you are really doing is using an electrical impulse to move the data from your camera to the computer. However, most people don't realize how fast electricity travels. Depending on the gauge of wire involved electricity moves at about 96% the speed of light on unshielded copper, to 66% the speed of light through a coaxial cable. (In a vacuum electricty moves at the speed of light). This is known as the Velocity of Propagation (VoP). A VoP of .70 corresponds to a speed of approximately 210,000,000 meters per SECOND or 4.76 nanoseconds to travel one meter. So, even if the balum is causing a 10% loss of speed your data would still be traveling through that short cable at over 1/2 the speed of light!

Since I'm rambling, that's how you are able to use features like IM on your computer...the only reason the person you are sending something to doesn't recieve it within a second of the time you hit send (because of the amazing speed of electricity) is that delays occue in processing the data and routing the data through the telephone/cable TV networks (depending on what you are using). In other words the servers and the networks are what slow everything down. The superfast processing speeds of todays switches, fiber optic cables and microprocessors allow a message to be recieved thousands of miles away just seconds after you press 'send'.

Fascinating and informative...thanks Rich and you too Mike. Well done guys!! :o)

Now it is more understandable... thanks guys.. your the best!