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Talking about the structure and technical principle of piezo
Release Time:2019-01-19    Clicks:   
The piezoelectric buzzer of the buzzer manufacturer adheres a piezoelectric ceramic piece that has been pressed by a high voltage to a vibrating metal piece. When an AC voltage is applied, mechanical deformation stretches and contracts due to the piezoelectric effect, and this characteristic is used to vibrate the metal piece to make an audible sound. The piezoelectric buzzer is divided into a feedback buzzer (self-excited) and a non-return buzzer (external excitation). When the feedback buzzer is matched with the positive feedback oscillation circuit, a single tone with the same frequency as the resonant cavity is generated; and the non-returned buzzer can be combined with an external oscillation circuit to select any frequency to emit sound.
1. The following are the fixing methods of two piezoelectric buzzers:
1. Peripheral support mode - Fix the outer edge of the buzzer piece in the resonant cavity. Generally, there is no feedback buzzer, and the buzzer must match the frequency of the resonant cavity to have a higher sound pressure output. And the external oscillating circuit generates a push signal to make the buzzer sound.
2. Node support mode - The buzzer piece is fixed in a ring structure of the same size as the diameter of the ceramic piece. If the resonant cavity is well designed and matched with the correct frequency feedback buzzer and positive feedback circuit, it will produce a large sound pressure and the correct frequency.
2. Piezoelectric buzzer specifications:
1. Rated Voltage piezoelectric buzzer is driven by square wave (V p-p)
2, Operating Voltage can work normally for the applicable voltage range, but does not guarantee that the lowest sound pressure can be achieved when the rated voltage is lower than the rated voltage
3, Consumption Current After the normal sound, the continuous consumption of current. And the current required to start the moment, generally need at least three times the continuous current consumption
4, Capacitance ceramic film capacity, the greater the capacity, the sound pressure is easy to enlarge, but more power
5, Sound Output, rated voltage, square wave, measured by Db table at a distance of 10cm
6, Rated Frequency buzzer still has sound at every frequency, the rated frequency refers to the recommended maximum frequency, and the sound pressure consistency is better.
7. Operating Temp. Temperature that maintains normal operation – 30–+70 degrees
Three. Piezoelectric buzzer selection:
1. Drive mode If the frequency signal cannot be supplied to the buzzer, consider using the built-in drive circuit to give DC voltage. There are also direct sounds, fast breaks, and slow sounds with different sound signals.
2. Size The size will affect the frequency, and the small size will be higher.
3. Voltage size Calculated by V 0-P (1/2 square wave).
4, the voltage size with square wave drive (V P-P), the higher the voltage, the higher the volume.

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