Why ANYONE would still use a 7805 in place of an "automotive grade" LM2940? The 2940 and its derivatives offer MUCH better protection and comparable regulation while offering superior overvoltage and reverse polarity and voltage spike protection - especially in battery powered and LDO use and/or extreme environments - car underhoods are DEFINITETLY extreme environments both environmentally and electrically.
Eclipze is right: The availability of cheap wall bug transformers these days makes one think twice about the need to do add on complexity of pre-regulation and/or finding other ways to find 5 or 12vdc - life is too short. A call to Digikey or Mouser is a quick, easy fix for a prompt low voltage add on wall bug. |