usb question

hey i saw some videos on diy usb fan, thought it was a great idea, so i tried to make one too for fun
so i took my old broken logitech usb mouse and cut it open, however when i opened it i saw black, white, red, green, a string, and a copper wire - like the picture on the imageshack link (sorry for the blurr)

http://img144.imageshack.us/my.php?image=dsc00210dk5.jpg

so i still only use the red and black wire right? and in what conditions should i not use the usb for powering (such as the product uses more than 500 milliamp?)

and just out of curiosity does any1 know whats that copper wire with no shielding is for?

thanks

Picture of usb question
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dj_oracol6 years ago
an 2.5" hdd drive draws about 700 milliamp end it works just fine with a cable of about 1 meter
aman0 (author) 9 years ago
i see, was wondering what the string and the copper wire was for when i cut it opened haha.. thanks for the replies and thanks for the tip tech king
trebuchet039 years ago
You can't draw more than 100mA without requesting it from the USB controller... If requested, you can get up to 500mA. Just FYI ;)
guyfrom7up9 years ago
and the string is for support or strenghth or something like that
the string is also used to fish the wires through the cable. and yeah, the bare copper is a shield. dont use usb for devices that need excessive current, or that cause oscillation on the feedback. i made a mouse pad with fans, and added capacitors to reduce oscillation or kickback. still not sure if it was necessary.
LinuxH4x0r9 years ago
Just use the red and black. The copper wire is connected to the outside of the plug. (the metal part that covers everything else) I think it's main purpose is as a shield.