27mm Piezoelectric transducers Piezoelectric Sensor , Piezo transducer


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27mm Piezoelectric transducers  Piezoelectric Sensor , Piezo transducer 

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Understanding Piezo Transducers

A piezo transducer is a device primarily used for converting an applied frequency to audible sound. It may be compared to a loud speaker, the only difference being the handling capacity and the operating principles.

A speaker is used for handling high power sound frequencies and is able to reproduce exactly what's been fed at the input.

However a piezo transducer may not be as efficient as a speaker with power and output quality but there are a few of the features which make these devices outstanding.

A piezo transducer is specifically suited for generating very high pitched sound outputs, which a speaker might not be able to do.

Moreover a piezo transducer is cheap, very compact and sleek and does not require complicated circuits for operating.

So basically these are used for producing high pitched notes applicable in musical horns, warning devices etc.



How Piezo Electric Transducers Work

A piezo transducer is round in shape with a metallic base, the 27mm diameter piezo transducers are more popular.
About 3mm from the outer periphery, the inner piezo material is coated on the metal base of a piezo.

This material is quite vulnerable especially while soldering wires on them.

Basically, these are two contact and three contact type. The metal base is used as the ground terminal and the inner poezo material coating becomes the positive terminal.

For the three contact type, the inner piezo material consists a small discretely separated piezo section which become the third contact and behaves mostly as the feedback element.

The above three contact piezo may also be used in two wire transducer application where the third small feedback contact is not used.

The external frequency from a piezo driver is applied across the  metal base and the inner piezo material, the piezo then starts vibrating at the applied frequency level, generating a high pitched sound.

However this sound can be very insignificant and low in volume unless the piezo is fixed over a special plastic housing with a center hole.

The size of the hole matters and should not be more than 8mm in diameter or less than 6mm in diameter.

The plastic housing should be such that the piezo is stuck with a adhesive over a raise platform just a couple of mm above the base of the housing which consists of the above explained hole.

The raised portion should be just 2 mm wide, barely supporting the circumference edge of the piezo.

The whole sticking (installation) procedure has been explained in this simple buzzer circuit article.


Generating Electricity from Piezo Transducer

Generating electricity from piezo could be as easy as making a flick with your finger..... curious to know how? Let's learn more about this amazing device called piezo, which can be used for generating music as well as electricity.

Piezo material is a crystalline substance which has the property of generating electricity when its crystalline structure is subjected to a certain mechanical stress level.

Conversely when the same crystalline structure is subjected to an electric current it exhibits an equivalent level of deformation which in turn causes a sound to be generated.

That's exactly why piezo elements are used in buzzers for generating sound by applying an pulsating voltage across it.

Therefore we can conclude that the discussed property of piezo material is flexible and reversible, meaning it allows both, generation of electricity when deformed, and generation of sound when electrified.

Having said this, care must be observed not to over limit the stress level on a piezo while attempting to generate electricity from it since the deformation limit of a  piezo element is
extremely small, exceeding which could result in breakage or permanent
damage of the element. 

For experimenting the generation of electricity from a piezo, the easiest way to access a piezo material is to procure the standard 27mm piezo element which are normally used in piezo buzzer circuits.

The picture below depicts a couple 27mm piezo elements which may be readily available in most electronic spare part stores.

The right side pic shows a 2-pin piezo element, while the other one represents a 3-wire, any of these will work for the experiment.

Once the piezo is procured, solder a couple of wires to it, connect a 20mA white LED across the other end of the piezo.

As soon as the above assembly is built, you can make the LED illuminate brightly momentarily by flicking the edge of the piezo with your finger.

Each time you strike the piezo with your finger, you can find the LED illuminating brightly during that instant.

Generating Electricity from Piezo buzzer

And somehow if the striking is sustained through some external means, would enable the LED to illuminate rapidly, or even continuously if a capacitor is connected across its leads.

If the output across the piezo wires is measured, you would be surprised to see the voltage to be as high as upto 5V depending on how hard the striking was.

While conducting the above experiment make sure the piezo is pinched tightly from opposite edge with your other hand fingers, do not clamp through any mechanical tool as that could crack the piezo causing permanent damage to the element 

Fancy Carom Board Using piezo Lit LEDs

The above explained concept of generating electricity from piezo transducer and illuminating an LED could be implemented in carom boards, for producing attractive LED illumination within the coins and also around the inner surfaces of the board rim.

SMD LEDs could be used for flush embedding them within the carom coins surface such that they do not affect the sliding effect of the coins.

The inner edges of the board could be also embedded with piezo/LED assemblies for generating the proposed piezo electric LED illumination.

Once this is done, each time the coins are struck or when coins hit the board edges the associated LEDs could be expected to light up brightly for that second producing interesting LED light show.

Using piezo electricity in Children Shoes.

The effect of piezo electricity could also be effectively used in children shoes, by suitably fixing the piezo, LED assembly beneath the heels of the shoes. This would enable the LeDs to light up brightly each time a step is taken by the child wearing these enhanced shoes.

Many more such innovative ideas could be implemented by using the proposed concept of generating electricity from a piezo buzzer element, if you think you have even more interesting ideas do let us know about it through your comments.


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27mm Piezoelectric transducers  Piezoelectric Sensor , Piezo transducer

27mm Piezoelectric transducers Piezoelectric Sensor , Piezo transducer

27mm Piezoelectric transducers  Piezoelectric Sensor , Piezo transducer