Q: I've just chopped open a USB cable to use with some project and I noticed that there was 4 wires in the middle, which were surrounded by tin foil or something then a silver braiding around that and then the outer cover. What's the braid for? Is it an armoured cable (seems unlikely) or does that carry the power and the small wires carry the data? Are all USB cables like this?
A: I don't know much about it, sorry. I do know (just chopped one open myself) the red wire is for power, the black is for the ground. The tinfoil is just a small protection feature which you can cut open easily. Edit: Two wires for power: +5 volts (red) and ground (brown) -- and a twisted pair (yellow and blue) of wires to carry the data. The cable is also shielded. Hope this helps!