The first thing I ever built without a kit was a 5 V regulated power supply using ... Well, you buy a switching power supply IC, add an inductor and you are done. Class dismissed.

The basic operation of a switch-mode power supply is fairly straightforward ... These supplies are not electrically the quietest or best regulated in the world, but they do have the advantage ...

The common type of power supply used with computers and other electronic equipment. The "switching" comes from switching a transistor on and off to create square waves for input to a transformer.