Can you help me to build a current source with minimum power loss? forward voltage of my sample leds is 3.2 - 3.6V @ 80mA. My power supply is 12.8 - 13.2VDC. it is not a good way to drive leds through a voltage source because brightness then depends on your supply voltage. Below is the circuit i think to use. but the problem is the power lost in regulator and resistor as heating.

R L1 L2 L3
o------|LM317|--/\/\/\/\--------|---|---|----
|_______________| |
13VDC |
|
o------------------------------------------------

Thanks.