The difference between piezo buzzer and magnetic buzzer (Part 4)

  From the introduction of previous issues, we know that both piezoelectric buzzer and electromagnetic buzzer can work under the condition of connecting DC voltage, which can be said to be their common point. Today we talk about the differences between the piezo buzzer and magnetic buzzer.

Magnetic buzzer:

1. sound pressure level around 85dB,

2.operating voltage at 1.5-24VDC,

3.current consumption more than 20mA 

4.the frequency is around 2700Hz.

Piezo buzzer:

1. sound pressure level more than 90dB,

2.operating voltage at 1-30VDC,

3.current consumption less than 20mA 

4.have wide frequency

  In a magnetic buzzer, a current is driven through a coil of wire which produces a magnetic field. A flexible ferromagnetic disk is attracted to the coil when the current is present and returns to a "rest" position when the current is not flowing through the coil. The sound from a magnetic buzzer is produced by the movement of the ferromagnetic disk in a similar manner to how the cone in a speaker produces sound. A magnetic buzzer is a current driven device, but the power source is typically a voltage. The current through the coil is determined by the applied voltage and the impedance of the coil.

 Piezo buzzers are used in similar applications as magnetic buzzers. Piezo buzzers are constructed by placing electrical contacts on the two faces of a disk of piezoelectric material and then supporting the disk at the edges in an enclosure. When a voltage is applied across the two electrodes, the piezoelectric material mechanically deforms due to the applied voltage. This movement of the piezo disk within the buzzer creates sound in a similar manner as the movement of the ferromagnetic disk in a magnetic buzzer or the speaker cone mentioned above.

  A piezo buzzer differs from a magnetic buzzer in that it is driven by a voltage rather than a current. A piezo buzzer is modeled as a capacitor while a magnetic buzzer is modeled as a coil in series with a resistor. The frequency of the sound produced by both magnetic and piezo buzzers can be controlled over a wide range by the frequency of the signal driving the buzzer. A piezo buzzer exhibits a reasonably linear relationship between the input drive signal strength and the output audio power while a magnetic buzzer's audio output declines rapidly with a decreasing input drive signal.