A series-connected string of incandescent light bulbs, operating on half-wave or full-wave rectified DC voltage, each having connected thereacross a filament voltage regulating shunting circuit which regulates the voltage across an empty or otherwise inoperative socket at substantially the same value as that across each of the remaining sockets in the string, thereby insuring continuous illumination of the light string. The voltage regulating shunting circuit of the present invention is a diode array formed of a plurality of series-connected silicon diodes and can be mass produced by using conventional manufacturing techniques at an ultimate selling price of approximately one cent.