What is the Difference between Active and Passive Transducers?

What Kind of Instrument is a Transducer?

A transducer is an electrical device that can change and alter any one form of energy into some other mode. In most cases, it can convert and transform one state of a signal into another. The method or process by which the electrical appliance functions and transfigures the forms of energy is known as transduction.

A transducer gets utilized at specific boundaries and margins related to the control system, automation, and measurements. The device performs this function and operates in this manner for particular instances and circumstances. These cases come up when a specified electrical signal undergoes and experiences alteration and conversion. It happens to and fro any form or state of a specific physical quantity. Such variables can consist of light, force, motion, torque, energy, position, etc.

What are the Distinct Parameters and Specifications that Come into Play to Characterize and Rate a Transducer?

A few factors and specifications come into play for the purpose and aim of characterizing a transducer. They can also rate the electrical device and depict its worth. A few of such parameters consist of the following:

• Dynamic Range

Dynamic range depicts the ratio between the highest degree of an amplitude signal that a transducer produces and translates. The other is the smallest value that the electrical gadget or device generates.

In most cases, a transducer has the scope to become even more sensitive and accurate. It is possible when the value and effect of the dynamic range become even higher.

• Noise

All transducers have the ability and capability to add and increase some value or degree of unwanted and random noise to the generated output. It differs for each type of electrical device.

For example, it comes in the form or state of electrical noise solely for electrical transducers. It arises due to the movement or a shift in the position of the charges. It can also be a result of thermal motion in a given circuit. The produced noises damage, impair, or corrupt small signals. For the larger ones, the effect is not so prominent and high.

• Repeatability

Repeatability can get defined as the capacity of any transducer to produce and generate an output. It should remain almost the same for subsequent measurements. It is feasible when the electrical gadget gets stimulated and influenced by a similar and unchanged input every time.

• Hysteresis

Hysteresis is one of the most crucial properties or features of a transducer. It stands true for any type or category of electrical device. It states that the output varies with and depends on the value of the current and previous input.

Let us use an actuator that incorporates and uses a gear train as an example. The appliance can experience and undergo some degree of backlash. It implies and points out the existence of a dead zone that remains present before the output reverses. It takes place solely in those instances where the device’s direction of motion becomes the complete opposite of what it initially was.

How Does an Active Transducer Differ From a Passive Transducer?

• Definition

An active transducer is a kind or type of electrical device that changes any non-electrical form or state of energy into an electrical one. It thus produces output as voltage or current without utilizing any external source of power or energy. It is also known as a self-generating transducer.

A passive transducer is another type that converts any non-electrical form or state of energy into an electrical one. However, in this case, it utilizes an external source of power and energy to do so. Its input parameters can get changed or altered due to the input signal. They can consist of resistance, inductance, and capacitance.

A passive transducer is also known as an externally-powered transducer.

• Working Principle

An active transducer works on the principle of utilizing the measured source and deriving energy from it.

A passive transducer works on the principle of utilizing power and energy from an external source. It uses these values to change and alter the physical properties of the transducer.

• Requirement of an External Source of Energy or Power

An active transducer does not require any external source of energy or power.

A passive transducer requires an external source of energy or power to work and operate.

• Quality and Resolution of Output

An active transducer produces an output of a relatively high resolution and quality.

A passive transducer produces output that does not have a high quality and resolution.

• Form of Generated Output

The generated output in the case of an active transducer is in the form of voltage or electrical current.

The generated output in the case of a passive transducer varies in quantity. It depends on and remains associated with the related passive elements.

• Type and Process of Conversion

The process and type of conversion of the input signal to the output signal in the case of an active transducer are simple.

The process and type of conversion of the input signal to the output signal in the case of a passive transducer are complex and intricate.

• Design of the Transducer

The design of an active transducer is exceedingly simple.

The design of a passive transducer is comparatively complex and intricate.

• Output Signal

The output signal produced by an active transducer can get generated and derived from the signal that has to get computed and measured.

The output signal produced by a passive transducer can get obtained and derived by receiving and acquiring the signal from the external source of power and energy.

• Requirement of Further and Additional Amplification

An active transducer requires some degree or extent of further and additional amplification to work and operate.

A passive transducer does not require any degree or extent of further and additional amplification to operate.

• Examples 

A few examples of an active transducer consist of a thermocouple, photovoltaic cell, and so on.

A few examples of a passive transducer consist of a resistance strain, photomultiplier tube, differential transformer, and so on.

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