i need to drive 2-3 1watt leds per arduino bin 2-3 now but may add 4-5 so from 6-15 1 watt leds brightness comtoled b PWM
led are 3-3.7 v i was hopeing to run them off 12v external pwr in sets of 3(series) gives 4 v but i have run these leds up to 6.5v and they hold out with heat sink.
so move voltage and current i guess. they need more than arduino can safely supply