Transducer Part 3 - The Piezo-electric Effect

Piezo is derived from Greek and means to squeeze. Certain materials that are squeezed or stressed will produce a voltage that is proportional to the level stress applied. Then again your lecturer should have told you all this. All I am doing is drilling through the brain to lay down even more neural interlinks. Although many materials exhibit the piezoelectric effect most common is Quartz crystal.
Another important point is that if a voltage is applied to a piezoelectric effect material it will stress. The effect is therefore reversible and this should be noted since piezoelectric is used in transducers that convert energy into electricity or vice-versa.

If we take a diaphragm and connect to it some piezo material and subject the arrangement to air that is vibrating then electrical voltages are produced proportional to the amplitude of the vibrations. This arrangement you might know better as a microphone. Equally we could with slightly modifications to the design, namely in size, make a device that will vibrate the air in proportion to a varying electrical signal, yes, a loudspeaker.

The air is not the only thing that vibrates since there is also vibration in the earth caused by earthquakes but I doubt many electrical apprentices will get involved with those. Some though will come across devices in industry that measure the vibration of machinery. By processing the vibrations generated by machines with computers it becomes possible to identify failure in components long before total failure occurs.

You are reading this text via a computer that I entered via a computer. Tick tock, tick tock, goes the clock. No I have not lost my reasoning since the piezo electric effect is used both in computers and in certain clocks that you know as quartz clocks. Most objects will have a frequency at which they will vibrate naturally at, this is called the resonant frequency. Quartz crystal is no different, so by differing the dimensions of the crystal you achieve a different resonant frequency.

There are many more applications of the piezoelectric effect used in transducers and sensors so look for blog entries for more later