Piezoelectric Acoustic Generators
Case Design for Nodal Mounting Method
The piezoelectric acoustic element with feedback tab (3-
terminal type) should be oscillated in the basic mode and
supported at the nodal point to obtain stability.
The nodal point of the disc which has diameter “a” is
located at the point of 0.224a from the edge of the disc.
However, the element has a smaller ceramic disc than metal
disc, which results in the nodal point being located at 0.15a to
0.20a from the metal disc edge.
A popular case design is shown in figure 10. The cavity is
designed in front of the transducer together with a short pipe
for the sound output release. The resonant frequency is
determined by the same formula as for the circumference
STANDARD SIGNAL GENERATOR (HP3310A)
SOUND LEVEL METER
(BRUEL & KJÆR, TYPE 26006)
TRANSDUCER HOLDING METHOD: FREE AIR
Sound Pressure Level
Resonant Frequency (fr), Resonant Impedance (Ro)
The resonant frequency (fr) is defined as the reading at
the point where impedance is at its minimum. Its impedance is
defined as the resonant impedance.
Static Capacitance (Cd)
Static Capacitance measuring frequency is 1 kHz, except
for low resonant frequency devices which are measured at 120
Hz. (See individual specifications.)