Here is a circuit for a 7805 regulator circuit. This design uses an external 12VDC wall transformer. I almost always use the DC output type wall warts because they have the bridge rectifier built in and there is very little difference in cost of a DC wart versus an AC wart. Plus it keeps me from having to put the bridge on the PC board.
You will also note that this schematic shows a sereis input diode. This is in the circuit to prevent reverse voltage connection to the circuit. (Unfortunately the wall warts come with center positive and center negative cords attached and when left to the user they can end up plugging in the wrong kind. The diode avoids the POOF!!



Michael Karas