Hmmm, not sure where this would fit(More the reason to reorganize)
But would it be ok to join the USB and external power jumpers into one?
I have a 64 LED Light bar, and it seems to run well off USB, but a multimeter reading gives it 2A of current when all the lights are on and it's powered from a bench type power supply(my uncles, (I don't have one).
The only power adapter I have is a 210MA 9V one, but I also have a 12V 700Ma, would the 12V work as far as converting it down to 5v?
If not, would it be possible to join both the USB and External pins to give me ~600ma available current?
I think that it's not a good idea to join the two. Anyway it would not give you enough currernt. You really need a suitable external powersupply.If memory serves me, You can only draw 200 - 300 mA from the voltage regulator on the Arduino board.
And if you have other USB devices on the bus you might only get 100 mA. You can request 500, but you aren't guaranteed to get it. I'd fairly strongly recommend against connecting power in parallel to USB. If the voltages aren't the same, you're going to have current flow between the two power sources, which could permanently damage your computer's USB. You should power the LEDs using an external supply that is separate from your Arduino, either using an adapter that can put out more current or using a battery.
Do you need individual control over all your LEDs or can you connect some in series to reduce power consumption? Also, if you can stand to have dimmer LEDs, you can decrease the current they draw.