A power supply for powering an electrical load, the electrical load generating load characteristic data that determines a power supply characteristic to be provided to the electrical load from the power supply, the power supply comprising a voltage regulator for generating an output voltage to be provided as the input voltage for powering the electrical load, the voltage regulator being responsive to a reference signal for setting a characteristic of the power supply, and a control circuit for generating the reference signal for the regulator, the control circuit being responsive to the load characteristic data from the electrical load and to a selection input for selecting the type of electrical load from a plurality of electrical load types, whereby the selection input determines the type of electrical load to enable the load characteristic data to be evaluated by the control circuit to generate the reference signal for the regulator.