What is the difference between electromagnetic buzzer and piezoelectric buzzer

buzzer is a commonly used sound element in the design of electronic products. According to the different working principle, can be divided into electromagnetic buzzer and piezoelectric buzzer. The buzzer commonly used in the development board and the experimental board is an electromagnetic buzzer, and the difference between them lies in the working principle. The working principle is detailed below.

1. Piezoelectric buzzer and electromagnetic buzzer are all buzzer series products, of which:

1. Piezoelectric buzzer is based on the piezoelectric effect of piezoelectric ceramics and uses pulse current to drive metal sheet to vibrate and sound. It consists of the following components: piezoelectric buzzer, resonant box, multivibrator, impedance matcher and housing.

2. The electromagnetic buzzer uses the electromagnetic principle to suck down the metal diaphragm after being energized, and bounces back according to the elasticity of the diaphragm when not energized. It consists of the following components: oscillator, electromagnetic coil, magnet, diaphragm and housing.

Through the difference between piezoelectric buzzer and electromagnetic buzzer, we can know that piezoelectric buzzer is mainly driven by square wave. Drive the electromagnetic buzzer to emit a 1/2 square wave sound; secondly, the piezoelectric type still needs a higher voltage to generate sufficient sound pressure, generally 9v voltage. The electromagnetic buzzer requires only 1.5 voltage.

3. The working principle of the electromagnetic buzzer

The electromagnetic buzzer is composed of a coil and a metal diaphragm. After a suitable voltage is applied across the coil, the current flowing through the coil will generate a magnetic field, thereby deforming the metal diaphragm. If a varying current is supplied, the buzzer will sound. The battery buzzer can be divided into active buzzer and passive buzzer according to whether there is a vibration source inside. There is a vibration source inside the active buzzer, only need to add appropriate voltage at both ends of the coil. However, the passive buzzer has no internal vibration source and requires an external square wave drive. Changing the frequency of the square wave can change the sound.

4. The working principle of piezoelectric buzzer

piezoelectric buzzer works by piezoelectric effect. The buzzer is mainly composed of piezoelectric ceramic and metal diaphragm. When the piezoelectric ceramic is energized, the piezoelectric ceramic will change, driving the deformation of the metal diaphragm, and the metal diaphragm will restore the original deformation after the voltage is removed. Therefore, the buzzer can only sound by adding different voltages to the piezoelectric ceramic. Ultrasonic equipment is also realized by this principle.

5. The difference between the two

The main difference in structure between the electromagnetic buzzer and the piezoelectric buzzer is the coil and the piezoelectric ceramic. Due to the existence of the coil, the electromagnetic buzzer will produce a peak when the coil is on and off, which will affect the sound quality. The piezoelectric buzzer has no coil, so there is no spike effect. In addition, the sound of the piezoelectric buzzer is proportional to the voltage, and the voltage level is generally higher than the electromagnetic buzzer.

6. The driving mode of both

The driving mode of both is basically the same, and both can be driven by triode. For passive buzzer, drive need to add freewheeling diode, active buzzer and piezoelectric buzzer is not needed.