power single LEDs with USB? Answered
I'm wanting to use some single 0603 LEDs here and there for a display. I want each light to have its own power plug. I'm figuring usb cables are a good way to do this (since I can power them by plugging into a hub, and retractable usb cables are cheap and handy). If anybody has a better solution, I'm open to ideas.
My question is whether there's some way to use a single resistor with the hub, instead of needing to add a resistor to each usb cable? I'm assuming no, but figured it doesn't hurt to ask.
Also, do I need different resistors depending on if it's usb, usb 2, or usb 3 hub/cables?
And finally, since I'm getting my 0603 LEDs from some pre-wired Christmas light strands (mostly white, but a few colored), I don't have exact specs. Is there a general standard that I should use for calculating which resistor to use? 3volts and 20mA sound good?