LM 7805 is a regulator IC and provides the necessary
five volts to the microcontroller IC. The project has input
supply of 12 volts DC and 7805 performs voltage
conversion. An integrated circuit voltage regulator is
connected to the output of a filtered rectifier and maintains
a constant output voltage or current despite changes in the
input, the load current, or the temperature. The most
popular IC regulator has three terminals, an input terminal,
an output terminal, and a reference terminal.