> Both of these solutions seem overly complex for the problem My instinct would be to go with your first thought, particularly if you're considering elegance in just the front end A micro does all the functions of a variable window comparator or other analogue-digital logic and could easily be expanded to include data logging, visual information, audible alerts etc Joe --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .