Ah, the venerable 7805, who amongst us has not used this popular linear regulator? This big chunky regulator will help you get your 7-35V battery or wall adapter down to a nice clean 5.0V with 2% regulation. Perfect for just about all electronics!  This is the TO-220 version, with up to 1.5A current capability, and has internal current limiting + thermal shut-down protection which makes it sturdy and pretty much indestructible - at least electronics-wise (we're pretty sure a hammer might work...)

This regulator has a ~2V linear drop-out. That means you must give it at least 7V to get a clean 5V out. There is a constant 'quiescent' current draw of 6mA.

This regulator can provide up to 1.5A as long as it has proper heat-sinking. The higher your input voltage and output current, the more heat it will generate. Without an extra heatsink, you can burn off up to 2W.  We like this calculator for determining your heat sink requirements It's a TO-220 package, so use 62.5°C/Watt junction thermal resistance. The wattage of your set up is = (InputVoltage - 5V) * AverageCurrentInAmps. E.g. a 9V battery and 1 Amp of average output current mean the regulator is burning off (9 - 5)*1 = 4 Watts! This setup would definitely need a heat sink!

This regulator does not require capacitors for stability, but we recommend at least 10uF electrolytic capacitors on both input and output.