This unit is a switching type voltage converter intended for use on vehicles with a 24V electrical system to power accessories designed for use on a 12V vehicle electrical system. The unit can deliver 6A continuous and 10A intermittent output load current and has output overload and over temperature protection with a fully automatic reset. The 24V input and 12V outputs share a common negative. The switching converter provides a low noise output closely regulated against variation of input voltage and changes in output load current. The unit is assembled in an aluminium extruded case. This allows reliable operation in harsh vehicle environments and areas of high ambient temperatures. The unit is also available with the addition of an independent low power converter which may be used as a continuous supply for memory maintenance.