This project shows how to build a Dual Variable Power Supply using LM317 and LM7805. It has two different outputs.. one stable at 5V and one variable, rated at 1 ampere each. The power comes from a transformer. Schematic and PCB is available on Eagle format.
A lot of emphasis was put on making this power supply very stable, a big 4700uF cap takes care of the ripple, then come the regulators, after that a 220uF clean any noises that the regulator might have let pass. The polyester capacitors do a more subtle filtering.
Dual Variable Power Supply using LM317 and LM7805 – [Link]