LIGHT SENSOR / DARK INDICATOR

A light sensor is a module which can sense the presence of light or in other words we can say that it is a dark indicator.


Means in the dark it gives us a output as 1.

Concept :-

LDR

                   In light sensor or in a dark indicator the sensing device is LDR. LDR is stands for Light Depended Resistor. In the presence of light LDR gives very high impedance up to 1M ohm so we get 0 output and in the presence of dark LDR gives very low impedance(negligible) so we get the output 1. A LDR is shown in figure below:-

LDR symbol

List of components :-

•                  330ohm resistor - 1
•                 1M ohm resistor - 1
•              100k ohm resistor - 1 
•                                 LDR - 1
•                         NE555 IC - 1
• 1000 pf ceremic capacitor - 1
•                            Red led - 1
•                       5V battery - 1

Circuit of light sensor :-
                                         We use 555 timer IC in astable multivibrator mode for this purpose.

After making this circuit you can test your output by applying a led with the resistance of 330 ohm.

PCB layout of light sensor :-

print this layout as it is and make your own pcb

m1 and m2 are male connectors M1=5V.

Images :-

                      

top view and 0 output in the presence of light

bottom view

1 output in the presence of dark

                    

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IR SENSOR

Here, we are going to make an IR sensor.

We will use a pair of IR Led's to make this sensor.

Concept :- 

               Two types of infra red led's are there, One is Emitter and other is Receiver. Emitter IR emits InfraRed waves up to a short range(less than 1 meter) and Receiver IR led receives the wave and gives the output in analog form.

After getting output from IR module it is fed to the A to D converter which converts the Analog signal into Digital signal for further processing.


List of components :- 

•            330 ohm resistance - 2
•            10k ohm resistance - 1
• 10k ohm variable resistor - 1
•                               Red led -1
•                         IR led pair -1
•                         5v battery - 1
•                       LM358 IC - 1
•            Male connectors
•          Connecting wires 

                                          

Circuit of IR module :-

negative pin of receiver is as output

A to D converter :-

                               An A to D converter is an Analog to digital converter. We will use operational amplifier for this purpose. An OP-AMP can compare the analog input from reference voltage and gives the output in form of 1 or 0.

               We will use LM358 IC for A to D converter. This IC have 2 OP-AMP. For the reference voltage we will use 10k ohm variable resistor. You can use any OP-AMP IC like - LM324, 741, LM339.

Circuit of A to D converter :-

Connect 4th pin as GND and 8th pin as VCC

Complete circuit of IR module :-

variable resistor is of 10k ohm and connect 4th pin of ic to GND and 8th pin of IC to VCC

PCB layout of complete IR module :-

DOWNLOAD THIS IMAGE AS IT IS AND PRINT YOUR PCB

THIS IS THE UPPER VIEW OF PCB, FROM THIS YOU CAN MOUNT THE COMPONENTS ON THE PCB  m2 and m1 are the male connectors

Images :-

                   

top view

AFTER FOLLOWING THESE STEPS YOUR IR SENSOR WILL BE READY TO RUN. IF YOU WILL PLACE ANY OBJECT NEAR TO THE IR LED THEN INDICATOR LED WILL BE ON.

NOTE :- If you want the long range IR sensor then you can use the monostable mode of 555 timer IC at the input of emitter IR led. Ciruit of that module will be updated soon.

Note :- We are using the blue and white pair of IR led. Blue is emitter and white is transmitter. You can cover the emitter led by any black cover from the sides(not from the front).

IF YOU HAVE ANY QUERY THAN CONTACT US OR GIVE YOUR QUERY IN THE QUERY OPTION.      

                                                            GOOD LUCK

More embedded projects >>....                             More MAT LAB projects>>...