Ok, I have a cheap 2AA headlamp with a pushbutton switch on the side and a bi-pin type bulb. So I don't have to worry about the switching. I know where to get a LS. Do I just connect it directly or do i need some kind of resistor? If so what size, I'm game to try this and I can follow directions and do simple math. E=I/R right? Should I put a heatsink on it?