1.Buzzer is an integrated structure electronic transducers, DC

voltage supply, widely used in computers , printers, copiers ,

alarms, electronic toys, automotive electronic equipment , telephones, timers and other electronic products for sound device .

2.Piezo buzzer divided into electromagnetic buzzer and buzzer.

3.The buzzer in the circuit use the letter “H” or “HA” ( old standard with “FM”, “LB”, “JD” , etc. ) indicates .

4.Piezo buzzer mainly by multivibrator, piezo buzzer , impedance matching and resonance box , casing and other components. Some piezo buzzer case is equipped with light-emitting diodes.

5.Multivibrator constituted by the transistors or integrated circuits . When switched on (1.5 ~ 15V DC working voltage ) , multi-

harmonic oscillator start-up , the output 1.5 ~ 2.5kHZ audio signals , impedance matching push piezo buzzer sound.

6.Electromagnetic buzzer from the oscillator, the electromagnetic coils, magnets, and other components diaphragm and the housing. After power on , the audio signal generated by the oscillator current through the electromagnetic coil , the electromagneticcoil generates a magnetic field . The electromagnetic coil and the diaphragm is the interaction of the magnet, periodicallyvibrating sound.