How about using a UV-sensitive LDR (Light Dependant Resistor) in conjunction with a PIC with analog capabilities. Then letting the PIC controll the UV-light for a set "ammount" of radiation. This way, it will work with different powered UV-tubes, and one could have a x-bit selector and the PIC would look up the exposure value from it's eeprom. Select board type / lamp type and press GO. Cool ? If only I could find some place with info on ammount of radiation needed for different brands of photoresist... Kyrre -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads