WHEATSTONE BRIDGE CIRCUIT DESIGN AND SIMULATION FOR TEMPERATURE SENSOR

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Group 01 <Please adapt this in the slide master>
MEASUREMENT AND SENSOR
TECHNOLOGY
WHEATSTONE BRIDGE CIRCUIT
DESIGN AND SIMULATION FOR
TEMPERATURE SENSOR
Group – 4A
PROJECT LAB EMBEDDED SYSTEMS
Chemnitz, 06/25/2015

CONTENTS
 Introduction & Motivation
 Objective
 General Concept
 Project Description
 Conclusion
 References
Seminar Automotive Sensors
Univ.-Prof. Dr.-Ing. O. Kanoun
Chair for Measurement and Sensor Technology

INTRODUCTION & MOTIVATION
Temperature plays an important role in many industries both
electrical & non-electrical for analyzing properties and behavior of
various objects.
Industrial Instrumentations.
Hot Wire Anemometers.
Lab Quality Measurements.

INTRODUCTION & MOTIVATION
Air, Gas & Liquid Monitoring.
Petrochemicals.
Air Conditioning & Refrigeration.
Textile Production
Plastics Processing
Remote temperature Sensing
for Automation Systems.

OBJECTIVE
 To Design a Bridge circuit to simulate temperature sensor.
 To Simulate in LTSpice, Labview & Matlab to analyze the behavior
of the temperature sensor.
 To design a PCB considering all the given design rules.

GENERAL CONCEPT – TEMPERATURE SENSOR
Feature Thermistor RTD Thermocouples
Temperature
Range (in °C)
-90 to 130 -200 to 850 -185 to 2300
Material Used
Ceramic or
polymer
Pure Metals Alloys
Accuracy/Linearity Poor Highly Accurate Fairly Good
Sensitivity Several Ω /°C
0.00385 Ω /°C (for
Platinum)
Tens of Micro-volts
per degree
Figure

BLOCK DIAGRAM
Resistance
Change
RTD Wheatstone
Bridge
Difference
Amplifier
Voltage
Change
Temperature
Change
Voltage
Response

RESISTANCE TEMPERATURE DETECTOR
 Available in 2-wire, 3-wire & 4-wire configuration.
 Variety of packages - wire-round and thin-film
 Excellent stability and reproducibility
 Very good Linearity
 Extremely accurate

RT = Resistance of the wire at temperature T°C
Ro = Resistance of the wire at temperature 0°C
T = Temperature in °C
α = Temperature co-efficient of resistance (°C-1
)
For Platinum wire RTD

Relation between temperature and resistance:
RT = R0[1 + AT + BT2
+ CT3
(T – 100)] (-200°C < T < 0°C)
RT = R0[1 + AT + BT2
] (0°C < T < 850°C)
Where RT = Resistance of the wire at temperature T°C
Ro = Resistance of the wire at temperature 0°C
α = 0.00385 (°C-1
)
A = 3.9083 X 10 -3
°C-1
B = -5.775 X 10 -7
°C-1
C = -4.183 X 10-12
°C-1

WHEATSTONE BRIDGE

DIFFERENTIAL AMPLIFIER

CIRCUIT DIAGRAM
Wheatstone
Bridge
Buffer
Difference
Amplifier
Voltage
Response
Temperature
Change

LTSPICE SIMULATION RESULT
Temperature (°C)
OutputVoltage
(volts)

LABVIEW SIMULATION BLOCK DIAGRAM
LabVIEW Block Diagram

LABVIEW SIMULATION RESULT
LabVIEW front panel

MATLAB SIMULATION RESULTS

PCB DESIGN
 Single Sided PCB
 PCB Size – 0.96 X 1.91 inch
 Space Between copper layers – 0.2mm
 Smallest Track Width – 0.2mm
 Layer thickness – 35µm

CONCLUSION
 Bridge circuit was designed to simulate the temperature sensor.
 Simulation completed in LTSpice, Labview and Matlab.
 The voltage output was verified.
 PCB was designed adhering to rules and guidelines.

REFERENCES
 Ramon Pallas-Areny, John G. Webster. “Sensors and signal
conditioning” – 2nd
ed. A Wiley – Interscience Publication.
 H S Kalsi, “Electronic Instrumentation” Tata McGraw-Hill, 2009
 D.Patranabis, “Sensors and Transducers” – 2nd
ed. PHI Learning
Pvt. Ltd., 2003.
 A.K. Shawney, Puneet Sawhney, “A Course in Electrical and
Electronic Measurements and Instrumentation” – Dhanpat Rai
Publications, 2012.
 Bela G. Liptak, “Instrument Engineers’ Handbook: Process
Measurement and Analysis” – 3rd
ed., CRC Press, 1995.
 Doeblin, “Measurement Systems Applications and Design” – 4th
ed., Mcgraw-Hill College, 1989.

ADDITIONAL INFORMATION
THEORETICAL CALCULATIONS
Temperature
(°C)
Resistance
(Ω)
Voltage
(volts)
Amplifier
Gain
Output Voltage
(Volts)
-200 18.52 -3.437394533 2.2 -7.56227
-150 39.72 -2.157171486 2.2 -4.74578
-100 60.26 -1.239860227 2.2 -2.72769
-50 80.31 -0.546004104 2.2 -1.20121
0 100 0 2.2 0
50 119.4 0.442114859 2.2 0.972653
100 138.51 0.807303677 2.2 1.776068
150 157.33 1.1139393 2.2 2.450666
200 175.86 1.374972812 2.2 3.02494
250 194.1 1.599795988 2.2 3.519551
300 212.05 1.795385355 2.2 3.949848

ADDITIONAL INFORMATION
THEORETICAL CALCULATIONS
Temperature
(°C)
Resistance
(Ω)
Voltage
(volts)
Amplifier
Gain
Output Voltage
(Volts)
350 229.72 1.96712362 2.2 4.327672
400 247.09 2.118902878 2.2 4.661586
450 264.18 2.254105113 2.2 4.959031
500 280.98 2.375190299 2.2 5.225419
550 297.49 2.484213439 2.2 5.46527
600 313.71 2.582847889 2.2 5.682265
650 329.64 2.672469975 2.2 5.879434
700 345.28 2.754222063 2.2 6.059289
750 360.64 2.829107329 2.2 6.224036
800 375.7 2.89783477 2.2 6.375236
850 390.48 2.961180884 2.2 6.514598

WHEATSTONE BRIDGE CIRCUIT DESIGN AND SIMULATION FOR TEMPERATURE SENSOR

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