I work at Halfords, and there are some super broight blue LED's that I thought would look nice below the strings on my les paul, between the pickups. They require 12 volts to power them. I was wondering if I could connect them anyway to something on the guitar that would power this, or would I need to hollow out a battery compartment for them using two 9v square bats?
No idea but i'd love to see the guitar once you've completed your task!
“being in a room and sitting there with a ghost, hearing their voice in your head and seeing them as clearly as I'm seeing you right now.”
No you're thinking of phantom power and it doesn't work with guitars, you need to add power through a battery.
Ah ok so I'd need to drill out some holes for the wires to run through the body, into a cavity where the batteries would be yeah? If I got two 9v batteries, would they stack to 18v? more than enough for the lights. The lights have a got a switch to save on the batteries. So if I soldered the battery terminals together with some wire, then connected the lights it should all work yeah?
Yeah it should but check what the voltage requirements are for the LEDs, you may need to add a resistor.
if they run on 12v then they already have a resistor built into the case (if they dont have a case then they probably need 3-4.5v to operate, with no resistor). you can power them from 1 9v battery. they will be slightly less bright. but super-brights are blinding anyway so imho this would be an improvement.
They're made to be put in cars around stereos/ in the dash/ door handles etc, so would be connected to the main bettery of the car. So I would guess they have a resistor in them. So they'll run off one 9v battery? That definitely saves space in my guitar, and I may be able to fit that into the back of the control compartment bit where the knobs are
Check out the bass of limp bizkit's bassist
all his basses fret markers have light built into them& it looks sexyyyyy especially when played in the dark check thier my way music video
is this what you are talking about ts? because a pic of what we are dealing with would have been great.

that's alot of LED's so current draw would be a problem for a single battery. wiring 2 in paralell will double the battery life (while still only supplying 9v)...

you could use a seperate adapter supply, but this will tie you down to a single spot unless you have a very long cord for it. but the advantage would be that you only need to mount a small adapter jack instead of routing for an installing a double battery box.