This project describes a home made power supply for a small server computer. It uses a toroidal power transformer (not the conventional transformer) to step down the mains AC voltage. The advantages of using a Toroidal is it is quiet, efficient and smaller in size. The transformer output is then rectified and capacitive filtered. DC regulation is achieved using PTN78020 for the 12v supply, and PTN78000 for the 5V one.
DIY power supply for home server computer – [Link]