I have a number of different LED:s in my storage box. The problem is that I for some unexplainable reason that I can't remember have throw away the original bag where the voltage and amp are posted. So now I have some small difficulties to know what resistance I should use so that I don't burn the LED:s So is there anyway to determine what volt and amp they are on a voltmeter or something? Amps would be the easiest one but it would be hard to determine voltage I could be wrong though. So anyone that's better on electronics that could answer this?