This document outlines a chapter on sensors and transducers. It begins by listing the chapter outcomes, which are to identify various sensor types, recognize real-life examples, identify technological applications, and describe how sensors can be utilized. The chapter then defines sensors and transducers as devices that convert physical quantities into signals. It proceeds to describe several common sensor types including photo-electric sensors, temperature sensors, special sensors like force and position sensors, and proximity sensors. Examples and applications are provided for each sensor type.

1. Chapter Outline Course outcomes covered
• Identify various types of sensors and transducers (Outcome No.7)
• Recognize and present real life examples of the aforementioned
concepts and interrelate some of them (Outcome No. 7)
• Identify technological applications of some of the aforementioned
concepts (Outcome No. 8)
• Describe how he/she can harness the benefits of some of the
aforementioned concepts
CHAPTER #6: SENSORS and Transducers (Outcome No – 7)
Sensors & Transducers
6.1 Photo-electric Sensors
6.2 Temperature Sensors
6.3 Some special Sensors/Transducers
& Proximity Sensors
6.4 Analysis of Sensors
A sensor converters the physical quantity to be measured into a signal which can be read by an
observer or by an instrument.
6.1 Photo-electric Sensors:
➢ They are sensitive to Light, like LED, IR LED, Photo diodes & Photo Transistor and LDRs
➢ They use photo sensitive materials like Gallium arsenide Phosphide, Aluminium gallium Phosphide, Indium
gallium nitride
Masader book link: https://www.masader.om/eds/detail?db=e000xww&an=104865
Author: Morris, Alan S. Book Name: Measurement and Instrumentation Principles
Chapter 13, 14, 18 & 19: Sensor Technology Page No’s: 246 to 382

2. Sensor name Symbol Input Output Applications
LED Voltage Light
Used for Indications (On or Off),
Traffic Signals,
TVs
IR LED Voltage
Invisible
Light
Detection of objects,
Used in Communication (Remotes)
Photo Diodes
&
Photo-
transistors
Light Current
Measurement of light intensity,
Compact disc players,
Smoke detectors
LDR Light Resistance
Lighting switch,
Alarm devices ( that detects for a light
beam),
Solar street lamps
Solar Cells Light Voltage
Power generation,
Heat generation
6.1 Photo-electric Sensors:
Masader book link: https://www.masader.om/eds/detail?db=e000xww&an=104865
Author: Morris, Alan S. Book Name: Measurement and Instrumentation Principles
Chapter 13, 14, 18 & 19: Sensor Technology Page No’s: 246 to 382

3. 6.2 Temperature Sensors: They are sensitive to Temperature
Temperature
Sensors
Symbol Input Output Applications
Thermo-
couples
Temperature Voltage /
Emf
• Used in Industrial applications like kilns,
gas turbine exhaust,
• Used in domestic applications like
Thermostats (part of heater or air
conditioner)
• As flame sensors
Thermistors Temperature Resistance
• Self-resetting over-current protectors,
• Self-regulating heating elements
Masader book link: https://www.masader.om/eds/detail?db=e000xww&an=104865
Author: Morris, Alan S. Book Name: Measurement and Instrumentation Principles
Chapter 13, 14, 18 & 19: Sensor Technology Page No’s: 246 to 382
Mainly there are 2 types of Thermistors:
Positive Temperature Coefficient (PTC) Thermistors: Resistance is directly proportional to Temperature
Negative Temperature Coefficient (NTC) Thermistors: Resistance is indirectly proportional to
Temperature

4. 6.3 Special Sensors & Transducers:
Type Sensor Input Output Applications
Force /
Pressure
Transducers
Strain Gauge
Force /
Pressure
Resistance
To Find the strength of Materials used
in Air crafts & buildings
Spring Balance
Force /
Mass
Displacement
To measure the weight &
To move Portable tools
Linear
Position /
motion
sensors
Potentiometer
Linear
motion
Resistance To divide voltage & for calibration
LVDT
Position
motion
Electrical Signals
Controlling of motors,
Drilling & process control
Speed
Sensors
Tacho-generator Speed Voltage AC and DC Motor control
Doppler Effect
Sensors
Speed Frequency To measure speed of the Motor / vehicle
Sound
sensors
Microphone Sound Electrical Signals Used in Mobiles and Cameras
Piezoelectric
Crystal
Electrical
Signals
Sound Buzzer & Loudspeaker
Masader book link: https://www.masader.om/eds/detail?db=e000xww&an=104865
Author: Morris, Alan S. Book Name: Measurement and Instrumentation Principles
Chapter 13, 14, 18 & 19: Sensor Technology Page No’s: 246 to 382

5. Masader book link: https://www.masader.om/eds/detail?db=e000xww&an=104865
Author: Morris, Alan S. Book Name: Measurement and Instrumentation Principles
Chapter 13, 14, 18 & 19: Sensor Technology Page No’s: 246 to 382
Proximity
sensor
It detects the presence of nearby objects
without any physical contact
Motion detectors (like Parking sensors),
Automatic door openers
6.3 Proximity Sensors