Active Buzzer Module Ky-012 Sensor \ is a kind of sound-producing equipment, which is widely used in computers, printers, copiers, alarms, electronic toys and so on. The buzzer is divided into active buzzer and passive buzzer. So what is active and what is passive? The "source" here refers to the oscillator circuit. In other words, the so-called active buzzer refers to the built-in oscillation circuit of the buzzer, which can sound as soon as the power is turned on. The passive buzzer needs to provide an external square wave of about 2~5khz.

Structure principle buzzer:
1. Piezo Buzzer: Piezo buzzer is mainly composed of multivibrator, piezoelectric buzzer, impedance matching and resonance box, shell, etc. Some piezoelectric buzzer boxes are also equipped with light-emitting diodes. The multivibrator is composed of transistors or integrated circuits. When switched on (1.5v-15v DC working voltage), the multivibrator starts and outputs 1.5-2.5khz audio signal, impedance matching pushes the sound of the piezoelectric buzzer. Piezo buzzer is made of lead zirconate titanate and lead magnesium niobate piezo ceramic materials. The ceramic surface is plated with silver electrodes, polarized and aging treated, and then bonded together with brass or stainless steel sheets.

2. Electromagnetic buzzer: It is composed of electromagnetic buzzer oscillator, electromagnetic coil, magnet, diaphragm and shell. After being energized, the current of the oscillator passes through the audio signal generated by the electromagnetic coil, and the electromagnetic coil generates a magnetic field. The electromagnetic coil and the diaphragm are the interaction of the magnet, which vibrates sound periodically.

? The active buzzer has an internal oscillation source, so it will beep as long as it is powered on
? The program control is convenient, the single-chip microcomputer can make a sound with a high and low level, but the passive buzzer can't do it .

Module interface description (3-wire system) :
? VCC External 3.3V-5V voltage (can be directly connected to 5v single-chip microcomputer and 3.3v single-chip microcomputer)
? GND External GND
? I/O External MCU IO port