being auto-electrical comps. you might try Motorola; they make filter and protection semi's for vehicle alternators,welders etc.or do a Google for 'transient protection' ----- Original Message ----- From: "Shawn Mulligan" To: Sent: Monday, November 14, 2005 10:24 PM Subject: [EE] Semi-Trailer Battery Power Filtering Has anyone here had experience designing battery voltage to 5V power supplies for use in PIC microcontroller applications, within the harsh heavy trucking industry? Specifically, conditioning and filtering for spikes and dropouts, etc. Can you direct me to any Application Notes? Thanks -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist