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What is the difference between active and passive buzzer?

Views:460     Author:Site Editor     Publish Time: 2021-02-22      Origin:Site

  The buzzer, also known as the sounder, is a miniaturized electro-acoustic device, for which working principle can be divided into two types: piezoelectric buzzers and electromagnetic buzzers. Also, even these two categories can be further subdivided. Although it may be easy to distinguish piezo buzzers and magnetic buzzers, a lot of piezo buzzers sold online with no instructions whether they are active buzzers or passive buzzers. So how can we tell if it is passive or active?

 

  What is the difference between piezo buzzers and magnetic buzzers?

  What is the difference between passive piezo buzzers and active piezo buzzers?

  What should be considered when buying a piezo buzzer?

 

What is the difference between piezo buzzers and magnetic buzzers?

  The piezoelectric buzzer is made of piezoelectric buzzer element, which is made of piezoelectric ceramic technology. It is necessary to plate electrodes on both sides of the piezoelectric element, which is mainly used for energizing and supplying the piezoelectric buzzer. After applying the driving control signal that affects the AC, the piezoelectric buzzer will produce a mechanical engineering deformation of the expansion and contraction because of the piezoelectric effect, which can effectively push the metal sheet vibration system attached with the piezoelectric ceramic sheet. Piezoelectric buzzer’s sound needs to vibrate back and forth through a piezoelectric element, so we need to use square wave signal data to drive, which requires a higher driving system voltage to get a larger sound.

  Compared with piezoelectric buzzer, electromagnetic buzzer works under lower voltage and higher current, while piezoelectric buzzer’s maximum sound pressure level capability is usually higher than that of an electromagnetic buzzer. In an electromagnetic buzzer, current is driven through a coil to generate a magnetic field. When the current exists, the flexible ferromagnetic disk is attracted by the coil. When the current does not flow through the coil, the flexible ferromagnetic disk returns to the "rest" position. The sound produced by the magnetic buzzer is produced by the movement of the ferromagnetic disk in a similar way to the way the cone in the speaker produces sound.

  The difference between a piezoelectric buzzer and an electromagnetic buzzer is that piezoelectric buzzers are of lower current consumption and works at higher rated frequency and wider operating voltage. The piezoelectric buzzer is modeled as a capacitor, and the electromagnetic buzzer is modeled as a coil in series with a resistor.

piezoelectric buzzers 

What is the difference between passive piezo buzzers and active piezo buzzers?

  The reason for distinguishing the two piezo buzzers is that they have different generation principles, and the parts used to be matched are also different.

  1. If you apply a DC voltage to them and make a buzzing sound, it means it is an active piezo buzzer.

  2. Using an ohmmeter, if you find resistance between the piezo buzzer’s pins, it is a passive buzzer.

  3. The active buzzer has a built-in oscillation source, so it’s simple to design in, but it oscillates at a specific frequency.

  4. Passive piezo buzzers need external driving circuit and is complex to design in, and it runs on AC only, they usually are called 'Transducers', 'Elements' instead of 'Buzzers'. While active piezo buzzers run on DC/AC, and are usually called indicators. 

What should be considered when buying a piezo buzzer?

  1. There are many specifications and varieties of piezo buzzers, such as piezoelectric buzzers and electromagnetic buzzers.

  2. Working voltage: Electromagnetic buzzer ranges from 1.5 to 30V and piezoelectric buzzer ranges from 3 to 250V. Therefore, the piezoelectric buzzer is more commonly used, and a voltage above 9V can get a relatively higher SPL.

  3. Current consumption: Depending on the voltage, it ranges from tens to hundreds of milliamperes. The piezo buzzer is so relatively power-saving that lower milliamperes can work normally, while the magnetic buzzer needs about three times  more current when it starts.

  4. Frequency ranges: Piezo buzzers tend to exhibit a more linear relationship between the input frequency and output audio power, while magnetic buzzers tend to have a less linear relationship. Therefore, piezo buzzers tend to have a wider range of usable frequencies than magnetic buzzers.

The above are some aspects that we need to consider when choosing a buzzer. You can choose according to your actual situation and the specifications of the buzzer.

 

Learning something about piezo buzzer can help you know the difference between the piezo buzzers and the magnetic buzzers, or even the more detail about the passive piezo buzzer and active piezo buzzers. If you want to buy high-quality piezo buzzers with reasonable price, Kailitech Company can provide you with the best products.


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