Seems like it should be dirt-simple, but I'm just not getting it. Vin of 0 to 5V gives current of 0 to max. Or it could be 5V to 0 gives 0 to max if that's easier. Don't know what max is yet. Probably 20mA or less. LED cathodes tied common to ground. Single 5V supply would be best, but +/- 15 ok. I'm blank. Thanks, Toby Paddock