Magnetic Buzzer

Magnetic Buzzer

Magnetic buzzer, or Electro-Magnetic buzzer, includes a silicon metal plate, magnet, coil and yoke, assembled within its plastic housing. The working principle of the magnetic buzzer is electro-magnetic effect. Input alternating V0p signal, the metal plate will vibrate up and down to produce sound. Magnetic buzzer is current sensitive and insensitive to voltage. That is, it's current driven. Some magnetic buzzer needs as low as 1.5V to produce enough SPL. However, input voltage range for magnetic buzzer is relatively narrow, for example within a few volts. If the user inputs more than the max voltage, she will not get proportionally large sound but the sound volume is saturated. Further more high voltages may damage the component.

If the buzzer contains oscillation circuit within it, then it's called self-driven buzzer or "indicator". If the buzzer doesn't contain any oscillation circuit, then it's called externally-driven buzzer or "transducer". The advantage of a transducer is that the user can freely design and designate input audio signal, keeping in mind that the input signal shall be around the resonant frequency to product max SPL. The advantage of an indicator is it can be easily driven by DC power, for example battery supply, but one should recognize that the output audio frequency is fixed by the internal circuit.

Magnetic buzzer is okay with 2,000hz~ 4,000hz resonant frequency output. It can play out mild reminder sound to hoarse alerting sound. The user is discouraged to use a piezo buzzer to play low frequencies, because low frequencies are not alerting enough and their sound volume is relatively low. The user should instead use micro-speakers to play out low frequencies or music and human voice. One of the features of magnetic buzzer is that the sound port can be on the upper side or on the left/ right side. The user can choose according to the final product's sound hole design.

Piezo buzzer usually comes with pin or SMT configuration, seldom with lead wire or connector The advantage of SMD magnetic buzzer is that it's thin, light-weighted and small. And the supply voltage doesn't have to be high, as batterly voltage can suffice. However, magnetic buzzer consumes more current because it contains coil. Note that magnetic buzzer is more suited in applications which stand still and in stable environments.