A conventional technique for controlling the intensity of an instrument cluster on a motor vehicle dashboard incorporates a mechanical rheostat in series with a voltage supply. The series resistance of the rheostat attenuates power delivered to the panel lamps and allows the automobile operator to adjust the light intensity from the dash panel. The use of a series limiting resistance in a rheostat dissipates unnecessary amounts of heat which is not only inefficient, but can alter the operating characteristics of other instrument panel components. In addition, the rheostat power adjustment technique of the prior art results in variable operation between different electronic subassemblies.