Sunday, January 13, 2013

BASIC ELECTRONICS TUTORIAL 5- UNDERSTANDING LDR


Hi… friends this time I am here with another interesting tutorial for electronics beginners this time we are going to discuss about Light dependent resistors or LDRs a very useful and widely used basic electronics component,…. So have a look…!!

INTRODUCTION

A photoresistor or light dependent resistor is a component that is sensitive to light. When light falls upon it then the resistance changes. Values of the resistance of the LDR may change over many orders of magnitude the value of the resistance falling as the level of light increases. It is not uncommon for the values of resistance of an LDR or photoresistor to be several megohms in darkness and then to fall to a few hundred ohms in bright light. With such a wide variation in resistance, LDRs are easy to use and there are many LDR circuits available.



 LDRs are made from semiconductor materials to enable them to have their light sensitive properties. Many materials can be used, but one popular material for these photoresistors is cadmium sulphide (CdS).
Light dependent resistors or LDRs are often used in circuits where it is necessary to detect the presence or the level of light. They can be described by a variety of names from light dependent resistor, LDR, photoresistor, or even photo cell (photocell) or photoconductor.






CIRCUIT TO UNDERSTAND WORKING OF LDR
 
Here is circuit with the help of which we can clearly understand the working of LDR. So first of all implement this simple circuit on bread board and then vary the light falling on LDR, you will observe when there is plenty of light LED glows but in absence of light LED turns off. 





Here you can use variable resistor provided to calibrate the LDR with the falling light intensity. 

Thus we can clearly understand the working of LDR as light this LDR can be used in so many small and standard projects.


I hope you guys found this article useful in case of any query, doubt or critical comment just leave a comment.


THNX…..:)


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