On 9/12/06, alan smith wrote: > > Well..expand the string to 100 LED's and the voltage requirement becomes > an issue with the client. They will deal with potential issues of > non-consistant brightness across the design, rather have 12V than 200V > sitting there. Obviously there are practical limits. A 20mA CCS with a compliance of 200V is a little scary. You didn't mention how many leds you were driving. Still, a CCS is how you get constant brightness. You could do one CCS per string, or use ballasting resistors to put some number of strings onto one CCS. A ccs can be just two transistors, and a few resistors, and dosen't need any huge voltage drop across it either. -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist