Transducers

Claimed by Derin Ozturk (dozturk7) --Dozturk7 (talk) 22:09, 2 December 2015 (EST)

Short Description of Topic

Transducers are devices that convert one form of energy to another. This topic will explain what transducers are, specifically bidirectional transducers, and their applications.

The Main Idea

A transducer, in general, is any device that converts one form energy to another. Usually this is some signal in one form of energy that is converted to signal in a different form of energy. There are many types of transducers, and the topic does incorporate many different concepts from physics and spans many fields, so this page will be only focusing on one type of transducers, bidirectional transducers, and two important applications: microphones and loudspeakers.

Bidirectional Transducers

In short, a bidirectional, or sometimes also called bilateral transducer, is a transducer that can convert some form energy from to another, such as an electric signal to an acoustical signal, but can also convert the other way, such as an acoustical signal to an electrical signal. Hence the name bidirectional.

Sound, Microphones, and Loudspeakers

A Brief Recap of Sound

Sound is a wave, that travels through a medium (usually the air, but it can also be any material such as water or steel) as a disturbance in that medium. This wave transports energy from one location to another location. This wave originates from the vibrating of an object or particles that causes the disturbance in the medium. Because there is particle to particle interaction, sound is considered a mechanical way. As a wave, sound has a frequency (sound is usually measure in Hertz, where 1 Hz is equal to 1 vibration per a second. The sensation caused by the frequency in sound is called pitch. A low frequency corresponds with low pitch, and vice versa.

Microphones

A microphone is simply a transducer which detects sound signals and produces electrical "images" of this sound. This image can be a voltage or current. These images are proportional to the sound signal.

There are several different types of microphones. The most common are dynamic microphones, ribbon microphones, and condenser microphones.

Dynamic Microphones

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The diagram above shows the inside configuration of a dynamic microphone. Sound enters into the cone of the microphone where it causes a diaphragm to vibrate. As the diaphragm vibrates, the coil that is attached to the diaphragm vibrates as well (this is proportional to the frequency at which the diaphragm vibrates!). The movement of the coil causes an induced changing current in the coil due to the magnet (remember Faraday's law). A dynamic microphone can simply be thought of as the inverse of a loudspeaker (see loudspeaker for more information).

Ribbon Microphones

A ribbon microphone is very similar to a dynamic microphone in that the principle of transforming the energy from the sound wave to an electric image is caused by a change in the position a conducting metal within a magnetic field.

This type of microphone, as shown in the diagram above, is made of a circular magnet, in which a "ribbon" of conducting metal lies between it. Sound waves cause a disturbance in the air that moves this ribbon. The ribbon moves, causing an induced voltage due to the generator effect (see Faraday's law), whereas this voltage is proportional to the velocity the ribbon experiences.

Connectedness

1. How is this topic connected to something that you are interested in?

I consider myself to be an audiophile, so I thought it would be really interesting to learn what goes into making speakers and other similar electronics.

1. How is it connected to your major?

I'm majoring in Computer Engineering. This field covers both the hardware and software side of electronics. Transducers are an important piece of hardware in todays electronics.

1. Is there an interesting industrial application?

Speakers, microphones, headphones, antenna, accelerometers, etc.

History

Put this idea in historical context. Give the reader the Who, What, When, Where, and Why.

Transduction was observed back in ancient times when Theophrastus noticed that a gem stone would become charged when heated. This phenomenon is called pyroelectricity, which is the ability for certain materials to generate a voltage when heated up or cooled down.

Transducing materials that could transduce both electric and magnetic fields were discovered in the 1800's. James Joule discovered "Joule magnetostriction" in 1842, which describes how a bar of iron constricts under the influence of a magnetic field. The Curie brothers also discovered how to create an electric charge by applying mechanical forces to quartz. This phenomenon is called piezoelectricity.

During World War II, nickel was a commonly used transduction material. Transducers allowed for the invention of sonar devices that would provide to be very beneficial during the war.

Today, all types of audio devices use piezo crystals (crystals that have piezoelectric properties), and transducers have many applications in every day electronics such as antennae, microphones, speakers, accelerometers, and pH meters.

See also

Are there related topics or categories in this wiki resource for the curious reader to explore? How does this topic fit into that context?

Faraday's Law

Capacitors

Sound

Further reading

Books, Articles or other print media on this topic

External links

[1]

References

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