This unit is a water resistant linear type voltage converter intended for use on vehicles with a 24V electrical system to power an independent 12V supply of either polarity. The unit also includes the addition of a low power converter which may be used as a continuous supply for memory maintenance. The unit can deliver 1.5A continuous and 2A intermittent output load current and has output overload and over temperature protection with a fully automatic reset. The linear output regulator 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 and encapsulated in silicone rubber. This allows reliable operation in harsh vehicle environments and areas of high ambient temperatures.