# How do I calculate voltage to each LED when more than 1 pin has an LED?

So I got one 3.1v 1000mA LED to work with a 10V 10ohm resistor and a 12v 1 amp power supply (people told me not to but it still works). I'm wondering if I were to add another LED to another pen, how would the power supply split the voltage/current to each pin? Sorry if this is a dumb question. If the voltage stays the same and the current is split in half (something tells me it isn't this simple), I would just need to get an 18 ohm 5 watt resistor? I'm probably wrong but I don't know how multiple pins emit energy when more than one LED is plugged in.

If I understand the question, each LED requires it's own dropping resistor, no matter how much current it is rated to draw.

Also, resistors do not have a voltage rating, ie. 10V 10 ohm resistor.

Paul

txmb95ads: So I got one 3.1v 1000mA LED to work with a 10V 10ohm resistor and a 12v 1 amp power supply (people told me not to but it still works).

Sure, it works, but people told you it was a bad idea.

You wanted to use three or four LEDs. That's a 3 or 4Amp supply. And 30-40watt of heat.

Why didn't you continue the previous posts. http://forum.arduino.cc/index.php?topic=344672.30 You almost had the answers.

Your way: Every LED gets a 10ohm/10watt resistor. Every LED gets a BUZ91 (not logic) mosfet. Everything gets hot. Leo..