A voltage regulator for regulation both of AC and of DC voltages, is provided in a regulator module (30) which uses a repetitive switching signal (32) to control a switch (36) allowing current to be supplied to a reservoir capacitor (42) by supply from an unregulated rail (18). The module contains a dual inductor (44, 46, 48) having first (44) and second (46) identical windings and a common core. A current pass capacitor (43) is also provided. When the switch (36) is closed, the first winding (44) delivers current to the reservoir capacitor. When the switch (36) is open, both the second (44) and the first (46) windings deliver current to the reservoir capacitor (42). The apparatus can support balanced operation, where pairs of switches are operated alternately and oppositely. The switching signal (32) can be suitably voltage restored to provide a signal suitable to control and operates switches (36). Different configurations of transistor switches (36) and diodes (38) are shown.