Difference between active and passive transducer

A transducer is a kind of electrical or electronic device used to convert one form of energy into another energy form.


There are different examples for transducer which is capable of energy conversion, microphones, solar cell, filament bulb, and generator or motor.

The transducer is mainly categorized into two, active and passive transducer, in this article we try to explain the difference between active and passive transducers.

Active transducer VS Passive transducer

ParameterActive transducerPassive transducer
DefinitionActive transducer is called the self-generating transducer, an active transducer had the ability to convert one form of energy into another form without any external sourcePassive transducer is called the externally energized transducer, a passive transducer converts a form of energy into another (electrical) by making use of an external source of power
DesignIt had a simple designIt had a very complex design
Working operationOperational energy is derived from quantity being measuredOperational energy is taken from an external power source
Output generationElectrical current or voltageVariations in quantity associated with passive elements are observed
Sensitivity or resolutionThe smallest changes happen in the quantity will be easily detected, but it had a low resolution compared to the passive transducer Passive transducers detect the smallest variation, it is more sensitive and accurate, and this is why passive transducers have higher resolution than active.
Signal conversionActive transducer had the simpler signal conversionThe passive transducer had a complicated signal conversion
Energy productionThe active transducer produces output from physical quantitiesThe passive transducer derive part of the power required the conversion from physical quantity under measurement
Output signal strengthThe signal obtained from the active transducer have lower amplitude, so an amplifier is required at the output section The output signal from the passive transducer did not require any amplification
AppsTachogenerator, thermo coupler, photovoltaic cell, piezoelectric crystal, and bourdon tube Potentiometer, thermistor, linear variable differential transformer (LVDT), photomultiplier tube, and strain gauge

Explain the key difference between the active and passive transducer

  1. Power source

difference between the active and passive transducer
difference between the active and passive transducer

The active and passive transducers are differed mainly due to the usage of power supply, an active transducer does not need any external power source to produce an output electrical signal, but a passive transducer needs an external power source for the output signal production.

  1. Transducer design

An active transducer had a simple design, this is because it had a self-energy generation capability and the passive transducer had a complex design due to multiple network arrangements.

  1. Working operation

     The active transducer operating energy is been generated from the quantity that we measured, but the passive transducer needs an external power supply to operate.

  1. Output generation

     The output of the active transducer is been generated as the variation of current and voltage, but a passive transducer variation happens on the quantity associated with the passive element is been observed.

  1. Sensitivity or resolution

     The active transducer is more sensitive than the passive transducer, but the active transducer had low resolution or accuracy than the passive transducer, this is because the smallest bit of variations are been measured with the passive transducer network.

  1. Output signal strength

The output signal we obtained from the active transducer will have low amplitude and power, so we need to amplify the signal with a booster amplifier, but the output signal we get from the passive transducer does not need any amplification.

  1. Applications of transducer

The active transducer had the ability to convert non-electrical energy to electrical energy and this is the procedure to calculate the variations using an active transducer, e.g.: Tachogenerator, thermo coupler, photovoltaic cell, etc.

The passive transducer converts the non-electric energy variations to electrical energy using an external power supply, e.g.: potentiometer, thermistor, linear variable differential transformer (LVDT), etc.

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