A demand-side dimmable LED lamp comprising: a direct current power source that is a battery or power supply having a first and second terminal of the direct current power source ; a dimmer unit having a first terminal electrically coupled to the first terminal of the direct current power source , the dimmer unit also having a second terminal, and one or more switches; and a lighting subsystem having a second terminal electrically coupled to the second terminal of the dimmer unit , wherein a first terminal of the lighting subsystem is electrically coupled to the second terminal of the direct current power source , wherein the lighting subsystem has a plurality of selectable power consumption levels selectable by the dimmer unit , the plurality of selectable power consumption levels including at least a first power consumption level and a second power consumption level that is less than the first power consumption level, wherein a percentage reduction in a brightness of the lighting subsystem at the second power consumption level as compared to the first power consumption level is less than the percentage reduction of the second power consumption level as compared to the first power consumption level, characterized in that the plurality of selectable power consumption levels is selectable by the dimmer unit by selecting an active network configuration from a plurality of transformable network configurations by activating the one or more switches whereby a power demand level of the lighting subsystem is changed, wherein the plurality of transformable network configurations are mutually transformable passive networks comprising LEDs and resistors. a direct current power source that is a battery or power supply having a first and second terminal of the direct current power source ; a dimmer unit having a first terminal electrically coupled to the first terminal of the direct current power source , the dimmer unit also having a second terminal, and one or more switches; and a lighting subsystem having a second terminal electrically coupled to the second terminal of the dimmer unit , wherein a first terminal of the lighting subsystem is electrically coupled to the second terminal of the direct current power source , wherein the lighting subsystem has a plurality of selectable power consumption levels selectable by the dimmer unit , the plurality of selectable power consumption levels including at least a first power consumption level and a second power consumption level that is less than the first power consumption level, wherein a percentage reduction in a brightness of the lighting subsystem at the second power consumption level as compared to the first power consumption level is less than the percentage reduction of the second power consumption level as compared to the first power consumption level, characterized in that the plurality of selectable power consumption levels is selectable by the dimmer unit by selecting an active network configuration from a plurality of transformable network configurations by activating the one or more switches whereby a power demand level of the lighting subsystem is changed, wherein the plurality of transformable network configurations are mutually transformable passive networks comprising LEDs and resistors. <EOS>