Buzzer introduction

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.

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.

Speaker introduction

Speakers are divided into built-in speakers and external speakers, and external speakers that the general refers to the speaker. Built-in speaker refers to the MP4 player has a built-in speaker, so that users can not only through the headphone jack can also be built-in speaker to listen to the sound of the MP4 player. With a built-in speaker MP4 player, you can not use an external speaker, but also to avoid prolonged inconvenience brought headphones.

The parameters of the speaker refer to the specific performance parameters of the loudspeaker tested by a dedicated speaker test system, and the commonly used parameters include Z, Fo, η0, SPL, Qts, Qms, Qes, Vas, Mms, Cms , Sd, BL, Xmax, Gap gauss The following are the physical meanings of these parameters respectively.1.1Z: refers to the resistance of the speaker, including the rated impedance and the DC resistance (unit: ohm / ohm) Nominal impedance The nominal impedance of the loudspeaker, Z, is the minimum impedance modulus behind the first maximum of the impedance curve, which corresponds to the impedance value at point B in Figure 1. It is the basis for calculating the loudspeaker's electrical power DC Resistance DCR: Refers to the voice coil in the static state, through the DC signal, and the measured impedance value. We usually referred to 4 or 8 Europe is the rated impedance .1.2Fo (minimum resonance frequency) refers to the speaker impedance curve The first maximum corresponding to the frequency.