Abstract: A high voltage multiplexer, useful in power supplies for electrophotographic printers, that converts a high voltage DC input into an AC modulated DC signal that is selectively applied to one of a plurality of outputs. The selected output depends on signals applied to a set of control inputs. That multiplexer is useful in a power supply system having a high voltage DC source for producing the DC input and a clock input for setting the AC modulation frequency. That power supply is useful in an electrophotographic printer having a plurality of developers and a controller. The power supply system then selectively powers one of the developers as directed by signals from the controller.