Introduction to LDR

Introduction to LDR 18

Introduction to LDRI hope you all are fine; this is the fifth article in the series on the introduction of basic electronic components. In my previous article I have briefly discussed the Phototransistor in this tutorial I will discuss the Light Dependent Resistor commonly referred to as LDR.

 

Introduction to LDR:

After reading this post the reader will be able to learn about the working of the light dependent resistor, construction of the LDR, circuit and application of the light dependent resistor. So sit back, keep reading and enjoy learning.

 

What is LDR (Light Dependent Resistor):

Light Dependent resistor also known as the photoresistor is a two terminal passive electronic component that is made up of a semiconductor element or compound. As the name implies the resistance of the Photoresistor depends upon the intensity of light projected onto it. With the increase in the intensity of light the resistance of the light dependent resistor decreases. The photoresistor along with its schematic symbol is as shown in the following image:

The LDRs are used in a bridge sensor circuit on order to convert the light into the voltage and thus different actions can be performed for example by feeding the voltage signal into the microcontroller the circuit can be used to determine the darkness in the room and turn on or off the light.

 

 

Construction of the Photoresistor:

The photoresistor is made of the semiconductor material an important thing to note here is that unlike the photodiode or the phototransistor the photoresistor does not have PN junction. The photoresistor exploits the light dependent properties of the semiconductor material. Some of the semiconductor materials commonly used to manufacture the photoresistor are;

  • Cadmium Sulfide.
  • Lead Sulfide.
  • Cadmium Selenide.
  • Lead Selenide.
  • Indium Antimonide.

In a photoresistor it is desirable to increase the dark resistance and also to reduce the dark current. In order to achieve this, the resistive path on the photoresistor is designed in a zigzag manner.

 

Working of the Photoresistor:

 

Photoresistor works on the principle of photoconductivity. The Photoresistor is covered with the transparent object which allows the light to pass through it. When the light falls on photoresistor an electron from the valence shell gets excited and enters into the conduction band thus in this way the number of available of electrons for conduction increases and the resistance of the light dependent resistor falls.

Photoconductivity:

The photoconductivity is a phenomenon in which the absorption of light makes the material more electrically conductive.

Photoconductivity

The electrons jump into the conduction band from the valence only when the photon of sufficient energy is absorbed by the photoresistor. The energy that is required by the electron to excite from the valence band to the conduction band is called the energy gap and it varies from one semiconductor material to the other.

Applications of the LDR:

Although the Light Dependent Resistor is not a commonly used electronic element in electronic circuit however it is used in the embedded systems in which light is to be manipulated. Some of the embedded system applications of the Light Dependent Resistor are:

  • LDR is used in home automation system to automatically control lighting.
  • LDR is used in greenhouse monitoring system to regulate the light inside the greenhouse.
  • LDR is used as proximity sensor that measures the distance of the light source from the target object on which the sensor is mounted.
  • LDR is used in solar tracking system.

I hope this article would be helpful for you. I have briefly discussed the LDR, it basic construction, working and applications. That is all for now in the next article I will come up with more interesting topics in engineering. Till then stay connected, keep reading and enjoy learning.

18 Comments

  1. Hi it’s me, I am also visiting this site regularly, this website
    is genuinely nice and the viewers are actually sharing
    good thoughts.

  2. Pretty section of content. I just stumbled upon your weblog and
    in accession capital to assert that I get in fact enjoyed account your blog
    posts. Any way I will be subscribing to your augment and
    even I achievement you access consistently fast.

  3. Your point of view caught my eye and was very interesting. Thanks. I have a question for you.

  4. I like this website its a master peace ! Glad I detected this on google .

  5. FlipBooks are a great addition
    to any passive income strategy. Because once you create a FlipBook, market it, share it & Earn it, it can technically sell itself.

    Learn More https://www.youtube.com/watch?v=JfRrd79oCfk?16847

    RonaldWaype
  6. I think the admin of this site is actually working hard in support of his web page, because here every information is quality based data.

    Feel free to visit my homepage vpn special coupon

  7. What is Boostaro? Boostaro revolutionizes romantic performance enhancement through its reliance on the wisdom of natural ingredients

  8. What Is Sugar Defender? Sugar Defender is a natural blood sugar support formula created by Tom Green. It is based on scientific breakthroughs and clinical studies.

  9. continuously i used to read smaller posts that as well clear their motive, and that is also happening with this piece of writing which
    I am reading at this place.

    Feel free to surf to my web-site … vpn code 2024

  10. I have been surfing online more than three hours today, yet I never found any interesting article like yours. It is pretty worth enough for me. Personally, if all site owners and bloggers made good content as you did, the web will be much more useful than ever before.

  11. There is noticeably a bundle to know about this. I assume you made certain good factors in features also.

  12. Awesome blog! Do you have any suggestions for aspiring writers? I’m planning to start my own blog soon but I’m a little lost on everything. Would you advise starting with a free platform like WordPress or go for a paid option? There are so many choices out there that I’m totally overwhelmed .. Any tips? Appreciate it!

  13. Whoa! This blog looks just like my old one! It’s on a entirely different topic but it has pretty much the same layout and design. Outstanding choice of colors!

  14. I am thankful that I detected this site, exactly the right information that I was looking for! .

  15. We’re a group of volunteers and starting a new scheme in our community. Your web site provided us with valuable info to work on. You’ve done a formidable job and our whole community will be grateful to you.

Leave a Reply

Your email address will not be published. Required fields are marked *