In the selection process of the buzzer, understanding its classification and working principle is the basis, and combined with these principles, the key parameters that need to be considered in the selection can be more reasonably applied to the specific design.

First, according to the structure of the buzzer can be divided into piezoelectric buzzer and electromagnetic buzzer

1.piezoelectric buzzer

How it works:
The piezoelectric buzzer makes use of the piezoelectric effect of piezoelectric ceramics to drive the metal sheet to vibrate when energized, thus producing a sound. Because there is no coil inside, it will not produce reverse electromotive force, which is suitable for occasions with high requirements for electromagnetic interference. Selection parameters:

Rated voltage: The rated voltage of the piezoelectric buzzer is usually higher, and the selection needs to ensure that the power supply voltage matches its rated voltage. Usually the voltage range of piezoelectric buzzers is 3V to 30V.

Rated current: Piezoelectric buzzers have low current consumption and are usually suitable for low-power designs. Its current consumption is usually between a few milliamps and tens of milliamps.

Operating frequency: The operating frequency range of the piezoelectric buzzer is high, generally between 2kHz and 4kHz. The appropriate frequency needs to be selected according to the actual use, such as the alarm usually needs a higher frequency to improve attention.

Sound Pressure level (SPL) : Piezoelectric buzzers usually have a high sound pressure level and are suitable for applications that require high volume, such as industrial alarms or security equipment. Selection should be based on the application scenario to choose the appropriate sound pressure level, usually 85dB above can meet most needs.

Size and package: Piezoelectric buzzers are usually small in size and are suitable for equipment with limited space. When selecting, it is necessary to pay attention to whether its size is suitable for the design requirements, and choose the SMD or THT package according to the production process.

2. electric magnetic buzzer

How it works:
Electromagnetic buzzers sound by vibrating electromagnets and metal sheets. Its working principle involves the on-off current of the coil, which may produce high voltage reverse electromotive force at the moment of power failure, so higher protection requirements are required for circuit design. Selection parameters:

Rated voltage: Electromagnetic buzzers usually operate at a low voltage, suitable for low-voltage circuit systems. The typical operating voltage is between 1.5V and 12V, so when selecting the circuit, ensure that the supply voltage is consistent with its rated voltage.

Rated current: The current consumption of the electromagnetic buzzer is higher, generally ranging from tens of Ma to hundreds of MA. The design needs to pay attention to whether the current consumption is within the power load range, especially for portable devices, which may need to choose low-power products.

Reverse electromotive force (Back EMF) : The electromagnetic buzzer will generate a reverse electromotive force when the coil is on and off, which can be as high as tens of volts. Therefore, in the selection, appropriate protective measures need to be added to the circuit to prevent the electromotive force from causing interference or damage to other circuit components.

Working frequency: The working frequency of the electromagnetic buzzer is usually low, but the sound is loud, which is suitable for use in scenarios with low tone requirements. Its frequency is usually in the range of several hundred Hz to 1kHz, and the selection of the buzzer needs to be selected according to the specific sound requirements.

Sound pressure level (SPL) : The electromagnetic buzzer has a higher sound pressure level, but because of its lower sound frequency and thicker tone, it is suitable for reminder devices or simple alarms.

二、According to the oscillation source can be divided into active buzzer and passive buzzer

1. active buzzer

How it works:
Active buzzers have a built-in oscillator source, so only a power supply is needed to sound. Because no external drive signal is required, it is easy to use and suitable for occasions with low control requirements. Selection parameters:

Frequency: The frequency of the active buzzer is usually fixed, and the design needs to confirm whether its frequency meets the requirements. Although the fixed-frequency buzzer is simple to operate, its flexibility is limited and it cannot achieve complex audio output.

Current and voltage: active buzzer in the selection also need to pay attention to its operating current and voltage, these parameters determine whether the buzzer can work normally in the circuit.

Size: Active buzzers are often used in simple reminder and alarm scenes, and their sizes are more diverse, suitable for different design needs.

2. Passive buzzer

How it works:
Passive buzzers require an external supply of oscillating signals, so they are usually used in combination with control devices such as microcontrollers. Its advantage is that it can adjust the sound frequency through the control circuit, and even play simple music. Selection parameters:

Frequency range: The frequency range of the passive buzzer is wide, and the output frequency range of the control circuit should be considered when selecting the buzzer to ensure that the required audio range can be covered.

Current and voltage: Passive buzzers have low power consumption and are suitable for portable device designs.

Impedance: For passive buzzers, impedance matching is one of the key parameters. When selecting, ensure that its impedance matches the drive circuit, otherwise it may affect the sound quality or the efficiency of the buzzer.

Summary and application scenarios

In the selection process, different types of buzzers have different working principles, parameter requirements and application scenarios. Designers need to combine the project needs, comprehensive consideration of voltage, current, frequency, sound pressure level, temperature adaptability and packaging and other factors, reasonable selection of buzzer. For example:

Piezoelectric buzzer suitable for high pressure, lightweight design, strong anti-electromagnetic interference occasions;

Electromagnetic buzzer suitable for low voltage, high volume portable equipment;

Active buzzer is suitable for reminder equipment without complex control;

Passive buzzers are suitable for projects that require flexible audio control, such as simple music playback or sound effects devices.