What Types of Transducers are There?

Proper instrumentation is a key component to modern innovation. Instrumentation is used to measure and control different variables. This allows companies and individuals to gather reliable measurements during testing.

Accurate instrumentation systems measure variables such as temperature, flow, angle, force, and displacement. One important element of many modern, scientific instrumentation assemblies is a transducer.

Transducers are devices that are often employed in automation, measurement, and control systems. But what exactly are they? In this article we will talk about transducers: what they are, what they do, and what are the different types.

A transducer is any device that converts one form of energy into a readable signal. Many transducers have an input that is then converted to a proportional electrical signal. Common inputs include energy, torque, light, force, position, acceleration, and other physical properties.

The output obtained from transducers is always in the electrical form, which is proportional to the measured quantity applied to the device. For example, a load cell will convert an applied force to an electrical potential that is equivalent. The force is measured with strain gauges in a Wheatstone Bridge configuration. The strain gauges measure electrical resistance changes in response to an applied force. The signal from the strain gauge passes through signal conditioning, or amplification, before being output as an electrical signal to a form of Data Acquisition. 

What are the Two Main Types of Transducers?

There are two main types of transducers based on whether or not they need an external power source. These are active and passive transducers.

An active transducer is one that does not require any power source in order to function. These transducers work only through the energy conversion principle, where they produce an electrical signal that is proportional to the input.

An example of an active transducer is a thermocouple.

Passive transducers, on the other hand, need an external power source to operate. Their output signal is produced in the form of variation in resistance, capacitance, or other electrical parameters. These can then be converted to voltage signal or equivalent current.

A torque transducer is a passive transducer which varies the voltage of the electrical output from the cell when a torque is applied. The torque transducer can be used to measure the drive torque and breaking torque on a vehicle. 

What are the Different Types of Transducers Based on Function?

Beyond those two categories, there are many different types of transducers.

Transducers can be classified by principle of operation. There are chemical transducers, piezoelectric transducers, and mutual induction transducers. There are also electromagnetic transducers, Hall Effect transducers, and photoconductors. Photovoltaic transducers are also known as solar cells.

There are also different classifications of transducers based on the quantity to be measured. This includes temperature transducers, pressure transducers, displacement transducers, and flow transducers.

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