Development of an optical transducer for an electro-acoustic guitar

Abstract

This paper presents the development of an optical transducer (OT) for an electro-acoustic guitar. Two conceptual designs are proposed: one with one infrared light emitting diode (IR LED) and one photodetector, and the other with two IR LEDs and one photodetector. Both concepts are based on the top-to-bottom structure: IR LED is on the top, and the photodetector is at the bottom. After the preliminary tests, the latter design is selected as the proposed OT. The OT is fabricated on the PCB with proper electronic circuit, and mounted on the guitar. The developed OT is subjected to the performance evaluation with a dedicated measuring device. The performance of the OT is compared with commonly used piezoelectric transducer. Findings are summarized: (1) The output signals from the OT are much higher that those from the piezoelectric transducer in both average and peak-to-peak voltages. (2) The noise level from the OT is similar or less than that from the piezoelectric transducer. (3) SNR with the OT is increased by 45% in average, compared with the piezoelectric transducer.