What is the buzzer used for? Analysis of the working principle of the buzzer

What is the buzzer used for?

A buzzer is an electronic component that generates a continuous and sharp sound signal. It is usually composed of a diaphragm, an oscillation source, and a drive circuit, and is mainly used to issue alarms, reminders, or prompts.

Buzzers are widely used in various electronic devices and systems, including but not limited to the following:

1. Alarms and alarms: Buzzers are commonly used in alarm systems, security systems, and fire alarms. When the device detects an abnormal or dangerous situation, it will emit a sharp sound to alert people.

2. Prompts and reminders: In some electronic devices, buzzers are used to provide prompts or reminders, such as the "beep" sound emitted by a microwave oven when it has finished heating.

3. Indication and signal: Buzzers can also be used as sound sources for device status indication or signal transmission, such as prompt sound effects in electronic games.

4. Communication and interaction: In some electronic devices, buzzers can be used to interact with users through voice, such as electronic doorbells, alarm clocks, etc.

5. Fault prompt: The buzzer in some devices is also used to indicate equipment failure or error status, prompting the user to perform inspection or maintenance.

Types of Buzzers

From the perspective of structure, it can be divided into piezoelectric buzzer and electromagnetic buzzer:

① Piezoelectric buzzers work on the principle of piezoelectric effect of piezoelectric ceramics. When an alternating voltage is applied, the piezoelectric ceramics produce mechanical vibrations, making the buzzer sound. This type of buzzer usually adopts an integrated structure and has the advantages of stable frequency, beautiful tone, small size, light weight, and low power consumption.

② Electromagnetic buzzers work on the principle of electromagnetic induction. They are mainly composed of a coil and a magnet. When current passes through the coil, a magnetic field is generated, which interacts with the magnet to make the buzzer sound. This type of buzzer usually adopts a split structure and has the advantages of loud sound, wide frequency range, and heavy weight.

According to the driving method, it can be divided into active buzzer and passive buzzer: (the "source" here refers to the "oscillation source")

① The active buzzer contains an oscillation circuit inside, which can convert constant direct current into a pulse signal of a certain frequency, thereby realizing the alternating magnetic field and driving the buzzer to vibrate and make sounds. It does not require an additional drive circuit and can work as long as it is connected to a DC power supply. The working principle of the active buzzer is based on the piezoelectric effect, that is, the characteristic of piezoelectric materials (such as piezoelectric ceramics, piezoelectric films, etc.) to generate voltage when subjected to external forces, converting electrical energy into sound energy.

The advantages of active buzzers are that they are easy to program and can work by connecting to a DC power supply, and the program is simple. However, since they contain an oscillation circuit, the cost is relatively high, and the sound frequency is fixed.

② The passive buzzer does not have an oscillation source inside, so it cannot directly convert direct current into sound energy. It needs to receive a 2K~5K square wave signal to work, and generates an oscillation signal through an external circuit to drive the buzzer to sound. By adjusting the duty cycle of the input square wave signal, the volume of the buzzer can be controlled; by changing the frequency of the input square wave signal, the tone of the buzzer can be controlled (volume refers to the strength of the sound, that is, the vibration amplitude of the sound; tone refers to the height of the sound, that is, the vibration frequency of the sound).

The advantages of passive buzzers are that they are relatively cheap and the sound frequency is controllable, which can achieve the basic seven-note effect in music. However, since an additional driving circuit is required, it is relatively complicated to use.

A buzzer is usually composed of a diaphragm, a coil, and a magnet. Its working principle is as follows:

1. Diaphragm: The diaphragm of a buzzer is a thin and sensitive disc-shaped structure, usually made of metal or plastic material. It has good elasticity and vibration characteristics.

2. Coil: The coil in a buzzer is a coil of wire wrapped around the diaphragm. When the current passing through the coil changes, a magnetic field is generated.

3. Magnet: The magnet in the buzzer is usually a permanent magnet, which generates a stable magnetic field.

4. Current change: When the current passing through the buzzer coil changes, a force is generated according to the Ampere force principle, causing the diaphragm to interact with the coil.

5. Vibration produces sound: Due to the elasticity of the diaphragm, when the coil is subjected to force, the diaphragm begins to vibrate. The sound waves generated by the vibration propagate into the surrounding air, forming a perceptible sound.

6. Frequency control: The sound frequency of the buzzer depends on factors such as the speed of current change and the elasticity of the diaphragm. By adjusting the frequency and amplitude of the input current, the buzzer can be controlled to produce different tones and volumes.

What to do if the buzzer sound is too low

If the buzzer sound is too quiet, you can consider the following methods to increase its volume:

1. Check the supply voltage: Make sure the supply voltage of the buzzer meets its specification. If the supply voltage is too low, the buzzer may not produce the maximum volume.

2. Increase the drive current: The volume of the buzzer is related to its drive current. You can increase the volume by increasing the drive current. Please note that you must operate within the rated current range of the buzzer to prevent damage to the device.

3. Change the drive mode: The buzzer can achieve different volume effects through different drive modes. For example, using pulse width modulation (PWM) drive can provide higher volume. If you can control the drive mode of the buzzer, you can try to use a more suitable drive mode to increase the volume.

4. Increase the sound cavity: The volume of some buzzers is limited by the size of the sound cavity. By adding a suitable sound cavity, the resonance effect of the sound can be increased, thereby increasing the volume.

5. Use an external amplifier: If the above methods do not meet your needs, you can consider using an external amplifier to increase the volume of the buzzer. Connecting the buzzer output to a proper amplifier can provide a louder volume.

The above methods need to be operated according to the model and specifications of the buzzer. As a simple and effective sound generator, the buzzer plays an important role in various electronic devices and systems, helping people obtain information, remind attention, warn of danger, etc.