You can play any of the instruments in this book into a microphone to amplify the sound. However, undesirable feedback occurs under some conditions and the volume varies considerably depending on the distance between the instrument and the microphone. Enter the piezoelectric transducer.

A piezoelectric transducer converts mechanical vibrations into an electrical signal. The original piezoelectric device was a quartz crystal, which, when squeezed, produced a voltage proportional to the force of the squeeze. They still make those, but piezoelectrics come in a variety of forms these days. Small rod–shaped transducers are designed for clamping under the bridge of a stringed instrument and there are flexible film transducers that conform to irregular surfaces. We used a pair of typical under–bridge instrument transducers for this project.