I have just bought a 2x16 LCD and this serial backpack:
The datasheet says that when it runs with the backlight at full it draws ~60mA, and if I am not mistaken the Uno's max is 50mA. So considering that I am going to be running it along with several buttons and sensors I am definitely going to need an external power supply. Would running a 9V battery through a 7805 regulator be sufficient with the backpack? Or would I need to decouple it? Also do the capacitor values have to be exact or is some variation allowed?