[Led display Digital Voltmeter question]

I am looking to do the same project as nice ride....couldn't you just use the same battery that you are measuring with a regulator circuit regulated at 5 volts?

also i need to know how to get the 0-20 volt display scale...
what resistors and capacitances are needed????

thanks

Thanks everyone for the help ahead of time.... I have read everything, and reviewed everything, and I am ready to build this circuit; however has this question been answered?

I basically am building this circuit to measure the voltage of a car battery and would like it to just be a two wire hook up. If I can