Patent ID: 7432717

Claim:
A method of sensing a malfunctioning shunt across a failed filament in a light bulb in a group of series-connected miniature decorative bulbs, wherein said group of series-connected decorative bulbs is in a light string that includes wires connecting said bulbs to each other and conducting electrical power to said bulbs, said method comprising: passing a dual antenna sensor along said wires, sensing the strength of the AC electrostatic field around a portion of said wires adjacent to said sensor and producing a single electrical signal representing the magnitude of said field strength at a common output, wherein said dual-antenna sensor comprises a first antenna and a second antenna; placing a suspected failed bulb between the first antenna and the second antenna; moving said first and second antennas, so that a socket of the suspected failed bulb is adjacent first one of said first antenna and second antenna and then the other of the first antenna and the second antenna; if a failed bulb is between the first and second antennas, said first antenna sensing an AC electrostatic field when said failed bulb is adjacent said first antenna and said second antenna failing to sense an AC electrostatic field when said failed bulb is adjacent said second antenna; and producing an output signal when an AC electrostatic field is sensed by either antenna and ceasing to produce the output signal when the AC electrostatic field is no longer sensed.