Quote Originally Posted by Dave View Post
AndrewC, Why not just use a transistor and a couple of resistors?

Dave Purola,
N8NTA
To invert the signal or drive the leds ? These are Luxeon leds running at high power. They work best on constant current sources and buckpuks are great for driving them.

If I can do it with a simple line of code why add external parts ? Actually, my led drivers only go up to 1000mA and my leds can take 1500mA so I may just make my own constant current drivers (two transistors and a couple of resistors per channel) in which case 5V will be ON This particular project is for lighting a macrophotography stage - while focussing / adjusting I use the leds at constant low power but for actual exposures switch to a single high power pulse. Three channels for left, right and backlight.