ok i was daydreaming today in school about something ive been wanting to do, i wanna jerry rig a speaker into my bookbag so i can play my guitar from it, kinda like a miniamp effect. i know how to solder wires into speakers so this isnt a problem, but along the road i ran into a little problem. In order to play the guitar from it im gonna need a power supply of some sort to get the guitar to emit a sound to the speaker. the problem is that i got no idea where the hell i can connect it with out having to buy a whole make-a-circuit kit...guys help!