The document discusses various types of sensors. It defines a sensor as a device that detects changes in physical quantities and produces an output. Sensors are classified in multiple ways, including by whether they require external power (active vs passive), their detection means (electric, chemical, etc.), their conversion phenomenon (photoelectric, thermoelectric, etc.), and their output (analog vs digital). Specific sensor types discussed include ultrasonic sensors, passive infrared sensors, speed sensors, blind spot monitors, radar guns, temperature sensors, proximity sensors, infrared sensors, and ultrasonic sensors. The document also defines an actuator as a mechanical or electro-mechanical device that provides controlled motion, either linear or rotary, to position or control devices.

1. IOT Hardware and software
Unit-2
Vishal Choudhary
vishalhim@yahoo.com

2. What is a Sensor?
A sensor is a device that detects
the changes in electrical or
physical or other quantities and
thereby produces an output based
on the pre-set values entered or
the current conditions.

3. Classification of Sensors
 There are several classifications of sensors made by
different authors and experts. Some are very simple
and some are very complex. The following
classification of sensors may already be used by an
expert in the subject but this is a very simple
classification of sensors.
 In the first classification of the sensors, they are
divided in to Active and Passive. Active Sensors are
those which require an external excitation signal or a
power signal.
 Passive Sensors, on the other hand, do not require
any external power signal and directly generates
output response.

4. Classification of Sensors
 The other type of classification is based on the
means of detection used in the sensor. Some of
the means of detection are Electric, Biological,
Chemical, Radioactive etc.
 The next classification is based on conversion
phenomenon i.e. the input and the output. Some
of the common conversion phenomena are
Photoelectric, Thermoelectric, Electrochemical,
Electromagnetic, Thermo-optic, etc.

5. Classification of Sensors
 The final classification of the sensors are Analog
and Digital Sensors. Analog Sensors produce an
analog output i.e. a continuous output signal with
respect to the quantity being measured.
 Digital Sensors, in contrast to Analog Sensors,
work with discrete or digital data. The data in
digital sensors, which is used for conversion and
transmission, is digital in nature.

6. Ultrasonic sensor

7. ultrasonic sensors
 In industrial applications, ultrasonic sensors are
characterized by their reliability and outstanding
versatility. Ultrasonic sensors can be used to
solve even the most complex tasks involving
object detection or level measurment with
millimeter precision, because their measuring
method works reliably under almost all conditions.

8. passive infrared sensor
A passive infrared sensor (PIR sensor) is an
electronic sensor that measures infrared (IR) light
radiating from objects in its field of view. They are
most often used in PIR-based motion detectors.

9. Speed sensor
Speed sensors are machines used to detect the
speed of an object, usually a transport vehicle

10. Blind spot monitor
 A blind spot monitor is a vehicle based senso device
that detects other vehicles located to the driver’s
side and rear. Warnings can be visual, audible,
vibrating.

11. Radar gun
A radar speed gun is a device used to measure the speed of
moving objects. It is used in law-enforcement to measure the
speed of moving vehicles and is often used in professional
spectator sport, for things such as the measurement of
bowling speeds in cricket, speed of pitched baseballs, athletes
and tennis serves.
A radar speed gun is a Doppler radar unit that may be hand-
held, vehicle-mounted or static. It measures the speed of the
objects at which it is pointed by detecting a change in
frequency of the returned radar signal caused by the Doppler
effect, whereby the frequency of the returned signal is
increased in proportion to the object's speed of approach if the
object is approaching, and lowered if the object is receding.

12. Temperature Sensor
 One of the most common and most popular
sensor is the Temperature Sensor. A Temperature
Sensor, as the name suggests, senses the
temperature i.e. it measures the changes in the
temperature
 Temperature Sensors are used everywhere like
computers, mobile phones, automobiles, air
conditioning systems, industries etc. .

13. Proximity Sensors
A Proximity Sensor is a non-contact type sensor that
detects the presence of an object. Proximity Sensors
can be implemented using different techniques like
Optical (like Infrared or Laser), Ultrasonic, Hall
Effect, Capacitive, etc.
 Some of the applications of Proximity Sensors are
Mobile Phones, Cars (Parking Sensors), industries
(object alignment), Ground Proximity in Aircrafts, etc.
 Proximity Sensor in Reverse Parking is implemented
in this Project: REVERSE PARKING SENSOR
CIRCUIT.

14. Infrared Sensor (IR Sensor)
 IR Sensors or Infrared Sensor are light based
sensor that are used in various applications like
Proximity and Object Detection. IR Sensors are
used as proximity sensors in almost all mobile
phones.

15. Ultrasonic Sensor
 An Ultrasonic Sensor is a non-contact type device
that can be used to measure distance as well as
velocity of an object. An Ultrasonic Sensor works
based on the properties of the sound waves with
frequency greater than that of the human audible
range.

16.  Temperature Sensor
 Proximity Sensor
 Accelerometer
 IR Sensor (Infrared Sensor)
 Pressure Sensor
 Light Sensor
 Ultrasonic Sensor
 Smoke, Gas and Alcohol Sensor
 Touch Sensor
 Color Sensor
 Humidity Sensor
 Tilt Sensor
 Flow and Level Sensor

18. What is an Actuator?
 Actuator are mechanical or electro-mechanical devices
that provide controlled and sometimes limited
movements or positioning which are operated
electrically, manually, or by various fluids such as air,
hydraulic, etc. Two basic motions are linear and rotary.
Linear actuators convert energy into straight line
motions, typically for positioning applications, and
usually have a push and pull function. Some linear
actuators are unpowered and manually operated by
use of a rotating knob or handwheel. Rotary actuators
convert energy to provide rotary motion. A typical use
is the control of various valves such as a ball
valves or butterfly valves. Each actuator type has
versions for various power configurations and come in
many styles and sizes depending on the application.
Linear chain actuators provide push and pull motions