Piezo buzzer uses piezoelectric effect to work. The buzzer is mainly composed of piezoelectric ceramic and metal diaphragm. After being electrified on the piezoelectric ceramic, the piezoelectric ceramic will change and drive the metal diaphragm to deform. After the voltage is removed, the metal diaphragm will recover its original deformation. Therefore, it is only necessary to apply a varying voltage to both ends of the piezoelectric ceramic to make the buzzer sound. Ultrasonic devices are also realized by this principle.

From home appliances and security devices to automotive electronics and office automation devices, audio signals are essential for communicating information from a product to its end user. These audio signals can be produced by a variety of devices. The buzzer is the most commonly used device for this purpose. A buzzer, also known as a sounder, audio alarm, or audio indicator, is a basic audio device that produces sound in response to an incoming electrical signal.

What is a Piezo Buzzer?

Piezo buzzers are electric devices that generate tone. These lightweight and simple buzzers are inexpensive yet dependable, and they are available in a variety of sizes and frequencies to meet the needs of nearly any application.

The piezoelectric component is the key feature that distinguishes this type of buzzer . Special materials that exhibit the piezoelectric effect are used to make piezoelectric components. When an electric charge is applied to a material, it deforms due to the piezoelectric effect.

Piezo buzzers have the following general characteristics:

-3 to 250 V operating voltage -Typical current consumption of 30 mA

-Resonant frequencies in the range of 2 to 6 kHz

Because of their size variability and dependability, piezo buzzers are frequently used in home and automobile alarms, as well as computer devices.

Piezo Buzzer Design

A piezo element, which is a thin disk of piezoelectric ceramic adhered to a metal plate , is used in piezo buzzers. A silver electrode is applied to both sides of the piezoelectric element to allow for electrical contact . The entire system can be housed in a plastic case, with or without a drive circuit.

Piezo buzzers operate by utilizing the reverse piezoelectric effect, which occurs when a material deforms in the presence of an electric charge. A piezo buzzer operates by passing an alternating voltage through a piezoelectric ceramic material. When such an input signal is applied, the piezoceramic vibrates rapidly, resulting in the generation of sound waves.

Piezoelectric buzzer uses the piezoelectric effect of piezoelectric ceramic to drive the vibration of metal sheet and make sound; The electromagnetic buzzer is based on the principle of electromagnetism. When it is powered on, it absorbs the metal vibration film, and when it is not powered on, it bounces back according to the elasticity of the vibration film. Therefore, the piezoelectric buzzer is driven by square wave.

The electromagnetic type is driven by 1/2 square wave. The piezoelectric buzzer needs a relatively high voltage to have enough sound pressure. It is generally recommended to be above 9V. Some specifications of piezoelectricity can reach more than 120dB, and larger ones can easily reach 100dB. The electromagnetic buzzer can emit more than 85dB sound pressure with 1.5V.

What Are Magnetic Buzzers?

In that produces a tone, a magnetic buzzer is similar to a piezo buzzer. Magnetic buzzers , on the other hand, differ from piezo buzzers in their primary functionality.

Magnetic buzzers and electromechanical buzzers are more traditional than piezo buzzers in that they use a magnetic field to operate. Magnetic buzzers on piezo materials use an electric charge to generate a magnetic field, which allows another part of the buzzer to vibrate and produce sound.

Magnetic buzzers have the following key features:

-Operating voltage range of 1.5 to 30 V -Typical current consumption of up to 100 mA or more -Resonant frequencies of 1 to 3 kHz

Magnetic buzzers, like piezo buzzers, are used in household alarms and devices such as clocks, watches, and keyboards.

Magnetic Buzzer Design

Instead of a piezoelectric element, magnetic buzzers use an electromagnetic element. A coil of wire connected to the circuit within the buzzer produces the magnetic field. A flexible ferromagnetic disk is also included in the buzzer. The entire thing is encased in plastic.

Magnetic buzzers work on the basis of electromagnetic principles. When power is applied, current flows through the wire coil inside the buzzer, creating a magnetic field. When the magnetic field is activated, the flexible ferromagnetic disk is attracted to the coil and then returns to rest. The buzzer generates a fluctuating magnetic field that vibrates the disk by oscillating the signal through the coil. The buzzer is activated by this movement.

Key Specifications for Piezo and Magnetic Buzzers

When deciding between a magnetic buzzer and a piezo buzzer, the key specifications of each buzzer type, as well as any drive circuit limitations in place, often come into play. Magnetic buzzers, as previously discussed, operate at lower voltages and higher currents than piezo buzzers, but this is not the only factor to consider. The sound specifications for each type of buzzer must also be considered, as briefly discussed below-

Before we get into the details, let's define some key terms:

Resonant frequency: Each material has a specific frequency at which it tends to vibrate — for example, when plucked, the G-string on a properly tuned guitar will vibrate at the frequency of a G-note. This frequency is known as the resonant frequency. When a material is driven at its resonant frequency, it produces the loudest sound with the least amount of input power. When compared to magnetic buzzers, piezo buzzers have a higher resonant frequency.

The sound pressure level (SPL) is the difference in atmospheric pressure caused by a soundwave. It is proportional to the input voltage and is typically expressed in pascals or decibels. The SPL value will vary depending on how far the measurement is taken from the buzzer.

Frequency response is a measurement of how efficiently a buzzer can generate sound energy at a given frequency. The SPL vs. log frequency plot is commonly used to express this.

Magnetic Buzzer is composed of a coil and a metal diaphragm. After applying appropriate voltage to both ends of the coil, the current flowing through the coil will generate a magnetic field, which will deform the metal diaphragm. If a variable current is supplied, FBelec buzzer will make a sound. The battery buzzer can be divided into active buzzer and passive buzzer according to whether there is an internal vibration source. The active buzzer has a vibration source inside, which only needs to apply appropriate voltage to both ends of the coil; The passive buzzer has no internal vibration source, so it needs to be driven by square wave externally. Changing the square wave frequency can change the sound.

Working principle of piezo buzzer

In general, piezo buzzers have a more linear relationship between input frequency and output audio power, whereas magnetic buzzers have a less linear relationship. As a result, piezo buzzers typically have a wider frequency range than magnetic buzzers.

Choosing the Right Buzzer Type for the Job

When comparing piezo buzzers vs. magnetic buzzers for a specific application, all specifications must be considered. The electrical and physical parameters of each buzzer type must be considered first. The following is a summary of the specifications for each buzzer type:

Piezo buzzers have a wider frequency range and higher SPL values, as well as a high resonant frequency. Piezo buzzers require lower current and higher operating voltages.

Magnetic buzzers have smaller frequency ranges and SPL values, as well as lower resonant frequencies, than piezo buzzers. They also operate at lower operating voltages but with high current demands.

Audible sound transducers are another option for highly customized applications

Audible Sound Transducers: Transducers are made up of a casing, a piezo element , and an electrical contact. Engineers have more design flexibility in driving circuits, which means they can modify or optimize the frequency in their application.

These aspects must be considered when deciding between piezo and magnetic buzzers. Because each application is distinct, making a decision based on your specific application is critical. If you are interested in using piezo buzzers in your application, please contact FBelec to discuss your requirements.

FBelec provides a variety of piezo buzzer options to meet your requirements. Our piezo buzzers are available in a variety of sizes and configurations to suit a wide range of applications, from self-oscillating buzzers to multi-tone sound generators.

To learn more about our piezo buzzer products, please contact FBelec today.