Principle and quality discrimination of piezo ceramic elements

The mechanical multimeter can be used to conveniently detect the quality of the piezo element piezoelectric diaphragm. The method is dial the multimeter to 25V, gently pinch the two sides of the piezoelectric element buzzer with the left thumb and forefinger, hold two test leads on the right, and the red pen is close to the potato chips. The black pen is placed on the surface of the buzzer, then the left thumb and the index finger are pressed hard, and then relaxed. The buzzer produces two voltage signals of opposite polarity, so that the pointer swings to the right - back to zero - to the left pendulum-zero, swing is about 0.1~0.15V. If the test pen position is exchanged and the test is repeated, the order of the pointer swing is to the left swing - return to zero - swing to the right - return to zero. Under the same pressure, the larger custom piezoelectric element is the pointer swing, the higher is the sensitivity of the buzzer. If the pointer does not move, it indicates that the piezo element film  buzzer is leaking or damaging inside.