In SX Microcontrollers, SX/B Compiler and SX-Key Tool, bean wrote: John, The datasheet shows that the forward voltage is 3.65V typical and could be as high as 4.2V. So with a 12 Volt supply you could only run 2 of them in series (with a resistor). Unless you bump up the voltage with a multiplier or something. And yes you will need a transistor because of the higher voltage and total current required. Or you may want to investigate something like the STP16C596, I just discovered this beauty for a project I'm working on. It would allow you to control 32 of your LEDs with nothing more than this chip, it's even got constant current so you don't even need a resistor. Bean. ---------- End of Message ---------- You can view the post on-line at: http://forums.parallax.com/forums/default.aspx?f=7&p=1&m=104178#m104191 Need assistance? Send an email to the Forum Administrator at forumadmin@parallax.com The Parallax Forums are powered by dotNetBB Forums, copyright 2002-2006 (http://www.dotNetBB.com)