There are many different kinds of buzzer to
choose, first we need to know a few parameters, such as voltage,
current, drive method, dimension, mounting type, and the most important
thing is how much SPL and frequency we want.
Operating voltage: Normally, the operating voltage for
a magnetic buzzer
is from 1.5V to 24V, for a piezo
buzzer is from 3V to 220V. However, in order to get enough SPL,
we suggest giving at least 9V to drive a piezo buzzer.
Consumption current: According to the different
voltage, the consumption current of a magnetic buzzer is from dozens
to hundreds of mill amperes; oppositely, the piezo type saves much
more electricity, only needs a few mill amperes, and consumes three
times current when the buzzer start to work.
Driving method: Both magnetic and piezo buzzer
have self drive type to choose. Because of the internal set drive
circuit, the self drive buzzer can emit sound as long as connecting
with the direct current. Due to the different work principle, the
magnetic buzzer need to be driven by 1/2 square waves, and the piezo
buzzer need square waves to get better sound output.
Dimension: The dimension of the buzzer affects
its SPL and the frequency, the dimension of the magnetic buzzer
is from 7 mm to 25 mm; the piezo buzzer is from 12 mm to 50 mm,
or even bigger.
Connecting way: Dip type, Wire type, SMD
type, and screwed type for big piezo buzzer are usually seen.
SPL: Buzzer is usually tested the SPL at the distance
of 10 cm, if distance double, the SPL will decay about 6 dB; oppositely,
the SPL will increase 6 dB when the distance is shortened by one
time. The SPL of the magnetic buzzer can reach to around 85 dB/
10 cm; the piezo buzzer can be designed to emit very loud sound,
for example, the common siren, are mostly made of piezo buzzer.