Thank you all for your replies. One last question, if you don't mind: if the max base current is no more than 1 mA, can I safely use the base-emitter zener effect without causing damage? Or even that little 1 mA is going to slowly destroy the transistor anyway? Thanks! Andrea -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads