In the passive mode the transducer acts as a sound receiver i.e. Piezoelectric material can be used for both active and passive transducer applications. The initial electrical signal has been delayed, a requirement often found in communication devices.
On reaching the end of the rod, the acoustic wave may be picked off as an electrical signal. It will travel in the quartz with the appropriate sound velocity. If an electrical signal is converted into an acoustic one at one end of a quartz rod, the signal will pass along the rod as an acoustic wave. The piezoelectric materials can be used as delay lines. In a phonograph cartridge, as the stylus traverses the grooves on a record, a pressure variation is imposed on a piezoelectric material located in the cartridge, which is then transformed into an electric signal, and amplified before going to the speaker. In almost all such cases the acoustic pulses are produced by piezoelectric transducers shock excited by electric fields. Acoustic pulses are used in underwater search and other applications. The crystal is here used as a transducer. Transducer :Īnother application of piezoelectric oscillators lies in the conversion of mechanical pulses into electrical ones, and vice versa. The use of quartz crystal oscillators in electronic circuitry is already very great. Especially cut quartz disks are generally used for this purpose, the stability being particularly high since the coefficient of thermal expansion of quartz is very low. The stability of the oscillatory system will be controlled by the constancy of the elastic constants of the crystal. If the crystal is placed between electrode and an alternating voltage at one of the resonant frequencies is applied, the amplitude of oscillation will build up at this frequency. Crystal Oscillators :Ī piezoelectric crystal will vibrate naturally in several mechanical modes, the frequencies of vibration being dependent on the dimensions of the specimen and the elastic constants of the material (f = 1/2l √Y/√ρ). The following points highlight the top nine applications and uses of piezoelectric materials in electrical engineering.
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