US Patent 7391161 Series wired light string with unidirectional shunts

A series-connected string of light bulbs, operating on AC voltage, each having connected thereacross a voltage regulating shunting circuit which regulates the voltage across an empty or otherwise inoperative socket so as to maintain unidirectional current across each of the remaining sockets in the string during one-half of an AC cycle, thereby insuring continuous but dimmed illumination of the light string. The voltage regulating shunting circuit of the present invention is a silicon rectifier diode connected in series with a voltage regulating diode. The voltage regulating diode may be an array of silicon diodes or a Zener diode. The voltage regulating shunting circuit can be mass produced by using conventional manufacturing techniques.