What is Transducer | Classification Of Transducer | Different Types Of Transducer | Advantages Of Transducer

What is Transducer

What is Trans­duc­er trans­duc­er is a device that con­verts one ener­gy into anoth­er ener­gy. Such ener­gy can be elec­tri­cal, mechan­i­cal, chem­i­cal, opti­cal or ther­mal. If a trans­duc­er gives elec­tri­cal ener­gy at its out­put it is called an elec­tri­cal transducer 

Such elec­tri­cal out­put can be volt­age, cur­rent or fre­quen­cy. Such sig­nals are gen­er­at­ed based on resis­tive, capac­i­tive and induc­tive properties 

The input lev­el for most instru­men­ta­tion sys­tems is not elec­tri­cal. If elec­tri­cal meth­ods are to be used for mea­sure­ment, manip­u­la­tion, or con­trol, the non-elec­tri­cal quan­ti­ty must gen­er­al­ly be con­vert­ed using an Transducer 

Basic Requirements Of Transducer 

Linearity

The input out­put char­ac­ter­is­tics for the trans­duc­er must be linear 

Ruggedness

Nec­es­sary safe­ty mea­sures should be tak­en to pre­vent any overload 

Repeatability

In the same sit­u­a­tion, the same out­put sig­nal should be avail­able when the same input sig­nal is giv­en at dif­fer­ent times 

High stability and reliability 

Trans­duc­er out­put should not be affect­ed by tem­per­a­ture, vibra­tion and oth­er cli­mat­ic changes 

Good Dynamic Response 

Depend­ing on the time, the out­put it gives should be equal to its input. This char­ac­ter­is­tic is tak­en as the fre­quen­cy response 

The trans­duc­er must pro­vide the max­i­mum ana­log out­put sig­nal with the high­est “sig­nal to noise ratio”. The out­put can be mea­sured direct­ly or after the required amplification 

Residual Deformation

It should not be dis­turbed even if the load is removed after using it for a long time 

Types Of Transducer 

• Resistive,inductive and capac­i­tive transducers 
• Pri­ma­ry and sec­ondary transducers 
• Active and pas­sive transducers 
• Ana­log and dig­i­tal transducers 
• Input and out­put transducers 
• Direct and Inverse transducers 

Classification Of Transducer

Trans­duc­ers are divid­ed into resis­tive, capac­i­tive and induc­tive depend­ing on their per­for­mance. They are fur­ther clas­si­fied as piezo­elec­tric, ther­mo­ele­cric, opti­cal, magnetorestritive 

Active and Passive Transducers

Trans­duc­ers are divid­ed into active trans­duc­ers and pas­sive trans­duc­ers accord­ing to their abil­i­ty to con­vert energy 

Active trans­duc­ers gen­er­ate an elec­tri­cal sig­nal direct­ly depend­ing on the phys­i­cal para­me­ter giv­en to it. No pow­er is required from out­side for their operation 

Active trans­duc­ers get the ener­gy they need from the sys­tem we are mea­sur­ing. There­fore active trans­duc­ers are also called self gen­er­at­ing type transducers 

Example

• Tacho­gen­er­a­tors that mea­sure angu­lar velocity
• Ther­mo­cou­ples that mea­sure temperature 
• Piezo­elec­tric crys­tal mea­sur­ing force

If a trans­duc­er changes the val­ue of elec­tri­cal para­me­ters such as resis­tance, induc­tance or capac­i­tance depend­ing on the input sig­nal giv­en to it, it is called pas­sive transducer 

Such trans­duc­ers require exter­nal pow­er to oper­ate. There­fore, such trans­duc­ers receive a small amount of ener­gy from the mea­sur­ing system 

Such trans­duc­ers are also called exter­nal­ly pow­ered trans­duc­ers. Exam­ples Strain gauges, Thermistors 

Primary and secondary transducers

Trans­duc­ers are clas­si­fied as pri­ma­ry and sec­ondary trans­duc­ers depend­ing on the type of appli­ca­tion. If a trans­duc­er sens­es the input sig­nal giv­en to it direct­ly and con­verts its phys­i­cal prop­er­ties direct­ly into elec­tri­cal sig­nal, it is called pri­ma­ry transducer 

Example

The ther­mis­tor that mea­sures the tem­per­a­ture sens­es the tem­per­a­ture direct­ly and changes its resis­tance val­ue accord­ing to the change in temperature 

If a trans­duc­er con­verts the giv­en input sig­nal into an elec­tri­cal sig­nal by first sens­ing (per­ceiv­ing) the giv­en input sig­nal through a detec­tor or sen­sor, it is called a sec­ondary transducer 

Exam­ple: The bour­don tube acts as the pri­ma­ry sen­sor when mea­sur­ing pres­sure. This con­verts the pres­sure into dis­place­ment. The LVDT then con­verts the dis­place­ment into an out­put volt­age. In this method the LVDT is called the sec­ondary transducer 

ADVANTAGES OF TRANSDUCERS 

• Elec­tri­cal oper­a­tions such as ampli­fi­ca­tion and atten­u­a­tion can be done easily 
• Dam­age caused by fric­tion is avoided 
• Mass-iner­tia prop­er­ties are reduced 
• Very lit­tle pow­er is enough to con­trol an elec­tri­cal or elec­tron­ic system 
• Elec­tri­cal out­put can be ampli­fied as required 
• The out­put can be viewed and record­ed even remote­ly from the sens­ing medium 
• The out­put can be adjust­ed to suit the con­trol units or the indi­cat­ing units 
• The sig­nal can be gen­er­at­ed by com­bin­ing the out­put of anoth­er sim­i­lar trans­duc­er or with the con­trol sig­nals in the required man­ner (scale)
• Elec­tri­cal out­put is easy to mea­sure, trans­mit and process 

Also Read: OPERATIONAL AMPLIFIER IC 741