Hi, I'm fairly inexperienced when it comes to electricity and circuits, so I could really use your help!
I want to make an LED flashlight. I plan on having around 5-15 LEDs connected in series, around 4-12 AA (1.2 volt rechargable NiMH) batteries in the flashlight, and some sort of resistor or voltage regulator.
Is there a good way of calculating how many batteries I need for a certain amount of LED's? Also, how can I calculate what type of resistor(s) I'm going to need?