I'm adding interior lighting to a structure -- my first one. This is large structure with a lot going on, so I have a number of different bulb types that I'd like to use. Some are incandecent and a couple are LED. Problem is, I don't know the voltage I need to be using. The bulbs come from various sources and I don't have any electrical data/info on what they're rated -- especially the ones I took from a string of Xmas lights. My question is -- is there a way for me to determine what a bulb's voltage should be? Or some way to figure that out?