The use of a inductor becomes the most crucial stage for driving a piezo electric transducer. The low power frequency which may be available from a relevant circuit or an IC is first amplified using a transistor, and further more the transistor output is pumped up using an inductor. However the amplification procedure is not by using conventional amplifying circuits as used in systems incorporating speakers, but rather it is simply implemented through an inexpensive inductor. The applied frequency will be required to be amplified very sharply or strongly before it can actually produce the intended effects in the piezo. How to Operate a Piezo with Maximum Sound The working voltage and resonant frequency can vary from 3 to 20 volts and 2 to 6 kHz, respectively, depending on the specific element and transistor utilized. The image provides common component values. In this oscillator, the inductor and capacitor that typically make up a Hartley circuit have been replaced by a piezoelectric device. Piezo Driver using a Single TransistorĪ basic "self-drive" piezo driver circuit is shown in the following figure. The oscillator/driver circuit is provided feedback from the phase-shifted signal in order to make it resonate at the element's intrinsic frequency. The physical distinctions between the two forms of elements are depicted in the figure below. Two main forms of piezoelectric elements are available: two terminal and three terminal. When an AC voltage is passed over the piezoelectric material's electrodes, the body expands and contracts in time with the voltage.Ĭonsequently, sound waves are produced as a result of the metal diaphragm bending in harmony with the ceramic substance.įor best efficiency, keep in mind that the mechanical resonant frequency of the element must coincide with the driving voltage frequency. Its thin shape guarantees that the metal diaphragm could be quickly activated into a condition of resonant mechanical vibration. The metal diaphragm is most often composed of brass or stainless steel and has a thickness of less than 0.5mm. Titanate zirconate and barium titanate are two common substances. The manufacturer's selection determines the type of ceramic that is utilized. Basic WorkingĪ thin circular slice of ceramic piezoelectric material placed on a metal diaphragm serves as the fundamental constituent for all forms piezo transducers. Partially this may be correct but might not be as easy as that. So does this mean that if we apply a frequency across the terminals of a piezo transducer, it will start generating the intended sound outputs? This property makes these devices typically suitable for buzzer related applications and in warning alarm devices. So my question is, is this the frequency at which the device is loudest but it is still possible to generate tones at other frequencies, possibly with reduced loudness ? None of these data-sheets provide a graph of the loudness-vs-frequency characteristics for the device.As discussed earlier a piezo transducer basically requires a frequency to vibrate and reproduce the required sound. This is where I ran into "resonant frequency" of piezo elements, which is mentioned in all the data-sheets. Was trying to understand the various device characteristics that these "pieze sounders" have, and how I could use them to generate a sound-pattern (involving at-least 2 different frequencies), without sacrificing too much on the "loudness" aspect. In another question I posed, there were couple of "piezo sounder" parts suggested for the purpose of a compact but reasonably loud, alternative to electro-mechanical hooters.
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