Today's vehicles feature a variety of electronic devices mounted within the vehicle itself. These devices contain power circuits, which are necessary in order for them to operate. The power circuits use a switching system that increases efficiency but is also a source of problematic noise. Noise suppression measures for the power circuits (DC-DC converter) of devices mounted in vehicles are reviewed below. The noise suppression measures and products reviewed here are not only limited to vehicles but also can be used with industrial and other equipment.