A piezoelectric sensor or element is a device that uses the piezoelectric effect, it is basically a device which converts voltage to vibration and vibration to voltage. It normally comes in handy to measure knock (knock sensor) or vibration (vibration sensor). Specifications Of Piezo transducer :
Outside Plate Diameter: 27mm (1.06 inches)
Element Diameter: 20mm (.79 inches)
Plate Thickness: ~0.5mm (.02 inches)
Lead Length: ~50mm (~2 inches)
Plate Material: Brass
Resonant Frequency: 4.6KHz +/- 0.5kHz
Resonant Impedance: 300 Ohm Max.
Capacitance: 20.0nF +/- 30% @ 1kHz
Package Contents:
1x (1 piece) 27mm Piezoelectric Disk Element Sound Sensor / Pickups with 2" Wire Leads