The printed circuit board needs a power supply. Since several of the components used require a fairly stable voltage, a voltage regulator will be applied. The LM7805 is a 5V voltage regulator that will provide the whole circuit board with a constant and stable voltage. To repress any peaks or sudden voltage fluctuations, we implemented a large capacity in between the two power lines. We supplied the voltage regulator with an incoming voltage of 12V. This may be less, however values over 7V are recommended to assure a sufficiently high and stable outgoing voltage. Be aware that this regulator also has an upper limit of voltage that may be supplied.
It is always a good idea to check out the datasheet when using a component that you are not familiar with. These documents usually contain a huge amount of handy or even critical information.
