V G wrote: > Reading the graph backwards, the current starts to drop at around 1V > of the "battery". Why is that? Connect the collector of Q2 to your 5V supply instead of the battery and th= e current sink should work down to a few 100 mV. ******************************************************************** Embed Inc, Littleton Massachusetts, http://www.embedinc.com/products (978) 742-9014. Gold level PIC consultants since 2000. --=20 http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .