Certainly you can power them directly from a power supply. You might want to add a switch to turn them off since the circuit is outside of the printer control board and GCode switching. I'm bummed now because I took my power supply and trimmed off all of the extraneous wires and left only the ones that feed my controller. I then taped and used head shrink on the nub of trimmed wires. Now I'll have to undo all of that to tease out a pair of 12V leads. Some light in there will be nice as I'm always in there there with my small LED flashlight.