source= http://www.piclist.com/postbot.asp?id=piclist\2002\09\23\220545a Roman said: "Re your over voltage question and possibility of a shorted switching transistor, I would just use a small fusible resistor 0.33 ohms etc in series with the input voltage. This will save your $100 equipment! :o)" My dad always used to put a light bulb in series with the supply to protect against shorts. Very low resistance when cold, but that increases as it heats and it drops most of the voltage when there is a short, etc... If you package it right, it can act as an overtemp sensor AND an overload indicator. --- James Newton: PICList.com webmaster, former Admin #3 mailto:jamesnewton@piclist.com 1-619-652-0593 phone http://www.piclist.com/member/JMN-EFP-786 PIC/PICList FAQ: http://www.piclist.com -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads