First, the introduction of buzzer

1. Buzzer role

Buzzer is an integrated structure of the electronic news device, the use of DC voltage power supply, widely used in computers, printers, copiers, alarms, electronic toys, automotive electronics, telephones, timers and other electronic products as vocal devices .

2. Buzzer classification

Buzzer is divided into two types of piezoelectric buzzer and electromagnetic buzzer.

3. Buzzer circuit graphic symbol

Buzzer in the circuit with the letters "H" or "HA" (the old standard with "FM", "LB", "JD", etc.) said.

Second, the buzzer structure principle

1. Piezoelectric buzzer

Piezoelectric buzzer is mainly composed of multivibrator, piezoelectric buzzer, impedance matching and resonance box, shell and so on. Some piezoelectric buzzer shell is also equipped with light-emitting diodes. Multivibrators consist of transistors or integrated circuits. When the power is turned on (1.5 ~ 15V DC working voltage), multivibrator starts to vibrate and output 1.5 ~ 2.5kHZ audio signal. Impedance matcher pushes the piezoelectric buzzer to sound. Piezoelectric buzzer made of lead zirconate titanate or lead magnesium niobate piezoelectric ceramic material. Placed on both sides of the ceramic silver electrode, the polarization and aging treatment, and then with brass or stainless steel sheet stick together.

2. Electromagnetic buzzer

Electromagnetic buzzer from the oscillator, solenoid, magnet, diaphragm and shell composition. After the power is turned on, the audio signal current generated by the oscillator passes through the electromagnetic coil, causing the magnetic coil to generate a magnetic field. Vibration diaphragm in the electromagnetic coil and the interaction of the magnet, the periodic vibration sound.