I cut the wire of a USB keyboard to supply 5V power to my Arduino. I expected to find Red wire for +5V, Black for GND, White for D-, and Green for D+. However, there is no Black, instead, there is a yellow wire! (I cut off the mouse cable too, but it has the same colors.)
I suspect that yellow wire is playing a role of black. So I connected the yellow wire to a LED's short leg (cathode) and red wire to LED's longer leg (anode). But, no light was emmitted.
When I tried yellow wire as -5V and white one for +5V, it works, but it is blinking. I understand this to mean that this is not stable power.
If I want to take stable 5v power from a USB port to illuminate an LED, what colors should I use?