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1. Department of Electrical Engineering
Presentation
Topic :- Transducer
By
Aniket Gunjal
Guided By :- Prof. Tushar Wadgule

2. Content
• Introduction
• Classification
• Types (Resistive, Inductive & Capacitive)
• Basic Requirements

3. Transducer
Pressure transducer
Stain gauge transducer
Piezoelectric transducer
LVDT transducer Capacitive transducer

4. Introduction
• A transducer is a device which transforms a non-electrical (physical
quantity) into an electrical signal.
• Electrical and Mechanical transducer are the major types of the
transducer.
Transducer
Non-electrical physical quantity
(tempraturre, pressure, sound, light,
etc.)
Electrical signal
(voltage, current, etc.)

5. CONSTRUCTION
• It consist two parts i.e. sensing element and transduction element.
• Sensing/Detecting element :- device which produce measurable
response to change in physical quantity.
• Transduction :- convert sensor output to suitable electrical form.

6. Working Principle
• When non-electrical physical quantity is present at the i/p of the
transducer, converts it into electrical signal with the help of sensing &
transduction element.

7. • Electrical Transducer :- a device capable of converting physical
quantities into a proportional electrical quantity such as voltage or
electric current.
Fig. Thermocouple

8. Fig. Burdon Tube
• Mechanical Transducer :- Transducer that respond to change in the
physical condition of system and gives output in other form. (output is
mechanical in nature like motion..)
Fig. Air Pressure Gauge

9. Classification
• Active and Passive Transducer
• Primary and Secondary Transducer
• Analog to Digital Transducer
• Transducer and Inverse Transducer

10. Active & Passive Transducer
Active transducer :-
• They do not require an external power. (called active transducer)
• Produce an analog voltage or current when stimulated by some
physical form of energy.
• It is also called as Self-Generating transducer.
• Ex. Thermocouple, magnetic coil & photovoltaic cell transducer.

11. Passive Transducer :
• Transducers which require an external power source for their
operation is called a passive transducer.
• Ex. LVDT (used as an inductive transducer , converts motion into an
electrical signal)
• Also called “External Powered Transducer”.

12. Primary & Secondary Transducer
• Primary :- A transducer which is directly connected to input called
primary transducer.
• Secondary :- A transducer which is not directly connected to input
called secondary transducer.

13. Analog & Digital Transducer
• Analog :- Transducers which covert input quantity into an analog
output which is a continuous function of time.
• Ex. Strain gauge, LVDT, thermocouple.
• Digital :- Transducers which convert input quantity into an electrical
output in the form of pulses and its output is represented by 0 & 1.
• Ex. Encoder, Digital resolvers, Digital tachometers, Hall effect
sensors, Limit switch.

14. • Inverse Transducers :-
• Transducer which converts electrical quantity into non- electrical
physical quantity.
• Widely used in feedback measuring system.
• Ex. Current carrying coil moving in a magnetic field, piezoelectric
crystal.

15. Types
• Resistive transducer
• Inductive transducer
• Capacitive transducer

16. Resistive Transducer
• In these transducers, the resistance changes due to the some physical
phenomenon.
R = ρ L/ A
• Where, R = resistance of conductor in Ω
ρ = resistivity of conductor material Ω-m
L = length of conductor in m
A = area of conductor in meter square
• Ex. Potentiometer, Strain gauge, Thermistors & Resistance
thermometer.

17. Fig. Sliding contact device
R = ρ L/ A
i.e. L ∝ R
A transducer like potentiometer works on sliding contact principle.

18. Inductive Transducer
• A transducer that works on the principle of electromagnetic
induction or transduction mechanism is called an inductive
transducer.
• Working principle uses :- Self Inductance , Mutual Inductance
& Eddy Current Production.
• Ex. Variable inductance transducer, Variable reluctance
inductive transducer, etc

19. Capacitive Transducer
• The value of capacitance changes due to change in input quantity that
is to be measured.
• Comprises of two parallel metal plates, separated by air or vacuum.
• Ex. Variable capacitance pressure gauge, Capacitor microphone &
Dielectric gauge.

20. Basic Requirements Of Transducers
• Ruggedness :- Capable of withstanding overload and provide safety.
(i.e overload protection)
• Linearity :- Input-output characteristics should be linear and produce
characteristics in symmetrical way.
• Repeatability :- It should reproduce same output signals.
• High output signal quality :- Quality of output signal should be
good.

21. • High Reliability and Stability :- It should give minimum error in
measurement.
• Good Dynamic Response :- Output should faithful to input with
time.