A lamp including a light source including at least one string of light emitting diodes (LEDs) within a tube body; end caps having contacts on each end of the tube body; driver electronics within the tube body including a filament detector portion provided by a passive resistance capacitor (RC) circuit that simulates the filament load of a fluorescent lamp when installed into a ballast containing fixture: and a power level selector switch in communication with the driver electronics for selecting the power level for powering the light source.