Buzzer is an integrated structure of electronic sound device, using DC voltage power supply, widely used in computers, printers, copiers, alarms, electronic toys, automotive electronic equipment, telephone, timers and other electronic products as sound devices. Buzzer is mainly divided into piezoelectric buzzer and electromagnetic buzzer two types. Buzzers are represented in circuits by the letter "H" or "HA" (older standards used "FM", "ZZG", "LB", "JD", etc.)
1. Piezoelectric buzzer Piezoelectric buzzer is mainly composed of multivibrator, piezoelectric buzzer, impedance matching device, sound box, shell and so on. Some piezoelectric buzzers are also equipped with light-emitting diodes.
2. Multivibrators are composed of transistors or integrated circuits. When connected to the power supply (1.5~15V DC working voltage), multivibrator vibration, output 100~500HZ audio signal, impedance matcher to promote the piezoelectric buzzer sound.
3 Piezoelectric Buzzer [1] is made of lead zirconate titanate or lead niobium magnesite piezoelectric ceramic material. A silver electrode is plated on both sides of the ceramic sheet, which is polarized and aged and then bonded to a brass or stainless steel sheet.
4. Electromagnetic buzzer Electromagnetic buzzer is composed of an oscillator, an electromagnetic coil, a magnet, a vibrating diaphragm and a housing.
After switching on the power supply, the audio signal current generated by the oscillator passes through the electromagnetic coil, so that the electromagnetic coil generates a magnetic field. The vibrating diaphragm vibrates periodically under the interaction of the electromagnetic coil and the magnet
Classification of BUZZER:
1. According to the principle of its driving mode, it can be divided into: active buzzer (containing drive line, also called self-excitation buzzer) and passive buzzer (external drive, also called he excited buzzer);
2, according to the different structure, can be divided into: electromagnetic buzzer and piezoelectric buzzer;
3, according to the different packaging, can be divided into: DIP BUZZER (pin BUZZER) and SMD BUZZER (patch type BUZZER);
4, according to the different current, can be divided into: DC buzzer and AC buzzer, DC is the most common piezoelectric buzzer, with piezoelectric material, that is, when the external force caused by piezoelectric material deformation piezoelectric material will produce charge. Similarly, piezoelectric materials deform when electricity is applied.
Electromagnetic buzzer, mainly by using the characteristics of electrical conductivity will produce magnetic field, with a fixed permanent magnet and electrical conductor to generate magnetic force to push the tympanic membrane fixed on the coil.
Because the two kinds of buzzer sound principle is different, piezoelectric structure is simple and durable, but the tone is single, suitable for alarm equipment. And electromagnetic because of good sound quality, so more used in speech, music and other equipment.
