Thanks to all who replied. I decided the down time from another blown chip wasn't worth using it just to gain some experience, so I replaced it yesterday with a much cheaper opto-isolator. Mark -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads