Introduction to Sensors | Types Of Sensor | Application

Introduction to Sensors


The sensor is a mechanical system that can respond to any environmental conditions (sound, heat, light), etc.

The sensor is a type of converter which converts any environmental change into a signal. People can take different sensations from the environment through their eyes, ears, and nose, but in the case of electronics, the matter is different. The apparatus can transform any event of the environment into an electrical signal. So it is a device that detects the physical property (heat, sound, light, etc.) and transmits the data to an electronic device. The sensor converts physical parameters (heat, sound, light, etc.) into signals that can be electrically measured.

Types Of Sensor 

There are basically two types of sensor:

  1. Analog sensor
  2. Digital sensor

Analog Sensor

  1. PT – 100
  2. Thermocouple

Digital Sensor

  1. Photo Sensor
  2. Proximity Sensor

Proximity Sensor

  1. PNP
  2. NPN

Analog Sensor

PT – 100(Platinum Resistance Thermometers)

introduction to sensors

Pt implies that the sensor is made of platinum and 100 implies that the sensor has 100-ohm resistance at 0’C. The main function of this sensor is to measure the resistance of the platinum element. That is, if the temperature increase, the resistance will increase.


introduction to sensors

A thermocouple is used to measure temperature. This thermocouple has a yellow and a red one. The thermocouple produces voltage depending on the temperature.

Digital Sensor

Photo Sensor

introduction to sensors

It is a type of sensor that can light sense and switch light.

Proximity Sensor

introduction to sensors


Proximity Sensor is a type of Sensor that can detect nearby objects without any touch. Generally, such a sensor creates an electromagnetic field or emits electromagnetic radiation and determines how close, far,  the object is from its change.

Different types of Proximity sensors are used to determine the nature of different types of objects, such as Capacitive Sensor is used to detect plastics, wood or various non-conductive / conductive objects. Inductive sensors are used to detect metallic magnetic materials, etc.

The Proximity Sensor has three wire black, blue, and brown.

BK = Black is the output.

BR = Brown is positive.

BU = Blue is negative.

There are two types of proximity sensors: 

  1. PNP
  2. NPN

PNP sensor’s switching is negative and the NPN sensor’s switching is positive.

PNP Sensor Connection:

introduction to sensors

NPN Sensor Connection:

introduction to sensors

Various sensors used in the electronics project

  • Temperature Sensor
  • Distance Sensor
  • Proximity Sensor
  • Touch Sensor
  • Photo Transistors
  • Photo Diode
  • Pressure Sensor
  • Magnet Sensor
  • Humidity Sensor
  • Motion or Movement Sensor


LDR is a Light Dependable Resistor. The LDR value is dependent on the light.

introduction to sensors


It has no specific values. However, it has the highest and lowest values. Another popular name for this is the photo register. Typically small LDRs have resistances of up to 1-mega ohm, whereas resistances of large ones can be around 1-kilo ohm.

Note that there are two types of LDR available in the market

  • When the light falls, the resistance decreases
  • Resistance increases when light falls.

Distance Sensor or Sonar Sensor

introduction to sensors

Different robots to measure distances, whether there are obstacles in the path of underwater sensors are used for communication.

Temperature sensor (LM 35)

introduction to sensors

Such sensors provide high voltage as temperature rises and low voltage with low temperatures. With such sensors, various temperature-related projects can be created and used in room temperature controllers, robots, etc.

Photo Transistors

introduction to sensors

It is a kind of transistor, it works as long as the light falls on it. The light acts as the base pin of the transistor. It acts like a switch when the current flows when the light is on, but not in the dark.

Touch Sensor

introduction to sensors

It is a kind of sensor where the signal comes out of it only when touched. It is useful to make anything of the touch.

Pressure Sensor

introduction to sensors

It is a type of sensor where it generates different signals depending on the pressure applied. It is very useful for measuring air pressure.

Magnetic Sensor

introduction to sensors

In the presence of a magnet, its signal value changes. Magnetic sensors are used in projects that use magnets, such as automatic door locking systems.

Humidity Sensor

introduction to sensors

As the humidity of the air changes, its signal also changes. This type of sensor can measure humidity.

Motion or Movement Sensor

introduction to sensors

This Sensor is a great use for making electronics fun projects. When you see something moving in front of it, it becomes active as it sends the voltage across the signal. These types of sensors are used for security control and traffic control.



Introduction to Sensors | Types Of Sensor  | Application
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Introduction to Sensors | Types Of Sensor | Application
Introduction to sensors: The sensor is a mechanical system that can respond to any environmental conditions (sound, heat, light), etc.
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