> There is s implest way if you check for a chip containing a voltage > reference and an operational amplifier. Maxim have a few like those. like http://www.voti.nl/shop/p/IC-LM10-DIP.html Wouter van Ooijen -- ------------------------------------------- Van Ooijen Technische Informatica: www.voti.nl consultancy, development, PICmicro products docent Hogeschool van Utrecht: www.voti.nl/hvu -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist