Instructables
Picture of Home made line tracer robot
IMG0615A.jpg
In this instructables I will show you how to make a line tracer robot without using any kind of microcontroller.
It is basically works on the property of reflection of light is greater from whiter surface than black surface. Hence when the robot sensors on the black path it receives less light than desired quantity of light and hence the motor stops rotating.
 
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Step 1: COMPONENTS

STEP 2 components
To make this robot you will need the following components:
1.LM358 op-amp chip
2. 220 ohm resistors  x  4
3. 1k resistor    x  2
4. BC547B transistor (NPN)  x  2
5. white LED    x  2 
6. red LED   x  2 
7. 3 or 6V DC geared motors  x  2 
8. copper clad circuit board or protoboard
9. 100k pot   x  2 
10.5k pot   x  2 
11. photo-diode   x  2 
& now you are ready to make ur project…  

Step 2: Circuit diagram

Picture of circuit diagram
Place the components in circuit as shown in diagram
(NOTE: HERE PHOTO TRANSISTOR ARE USED IN DIAGRAM BECAUSE PHOTODIODE IS NOT AVAILABLE IN SOFTWEAR. BUT U SHOULD HAVE TO CONNECT ANODE OF PHOTODIODE TO GND OF BATTERY AND CATHODE TO +VE OF BATTERY  i.e diode is in reversed bias.
I suggest you 1st test the circuit on breadboard. Try to solve all problems about connection and then finally place it on PCB or solder…….

watch following link for clear and enlarged circuit diagram:
http://www.instructables.com/files/orig/FKQ/FET5/GXSSLLIM/FKQFET5GXSSLLIM.png

Step 3: Making the PCB

Picture of Making the PCB
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Making the pcb as I shown in fig.
U can also use your own design or u can directly use the protoboard.

for more details and READY MADE PCB DESIGN CLICK: http://www.instructables.com/files/orig/FTJ/QTLQ/GZXW8JKS/FTJQTLQGZXW8JKS.png

Step 4: Drilling the PCB

Picture of Drilling the PCB
I drilled this PCB with my friend Ajinkya Dixit’s home made drill machine.

Step 5: SENSORS: the eyes..

Picture of SENSORS: the eyes..
IMG0650A.jpg
sensors are most important part of LINE TRACER..
here i used IR LED as transmitter and PHOTODIODE as receiver. u can also use bright red or white led but IR led increases the accuracy of sensor unit..

for details and READY MADE SENSOR BOARD DESIGN CLICK:http://www.instructables.com/files/orig/FIM/ZXX5/GZYCFV1I/FIMZXX5GZYCFV1I.png
harshbhardwaj11 months ago
Can i use LDRs instead of photodiode?
jpaul151 year ago
Sir it will work in bread board
vvirtucio1 year ago
,SIR, we've tried this in breadboard, we used photo diode(receiver) but whenever the motor is rotating and the output led is switched on, the IR led beside the photo diode is not luminating, and whenever the IR is luminating, the motor and the output LED is not working. Can you help us? please? we've followed your instruction about the photodiode.
its nice.. but i have a doubt in my mind that how the robot takes right and left turns ...that is i want to ask , that suppose the track is turning towards right then left sensor will sense that there is no black tape in front of it then how it activates the motors to make a turn please explain me sir ..... and if you get time then please email me at navjotacharya@yahoo.com explaining all the things in details. also add the pdf . as i am not the pro member and hence i was unable to download it.. please help me sir. thank you for listening me.
Pranjal Joshi (author)  navjotacharya1 year ago
When the track is turning right then right sensor sense the black tape & left remains on white. So the right motor turns off but left is still moving. hence robot turn to right. at that time when right sensor senses white both motor starts and it moves straight again travelling little distance on turn the right senses black and turn towards right. this cycle is repeated very rapidly and you will see that its turning smoothly to right/left.. :)
Gurdain2 years ago
how and where to connect wires from the pcb to the sensor.
i don't no the wiring plezzz can u tell me or can u post a video
also what type of motor should i use plezz tell me as soon as u can
anshi21922 years ago
i jst lv this site bcoz i lv robots
msadashiv2 years ago
i mean what goes where
botguy242 years ago
NICE! how bout a vid?
Pranjal Joshi (author)  botguy242 years ago
watch out the video... :)
Pranjal Joshi (author)  botguy242 years ago
i ll try if possible
msadashiv2 years ago
ca you please tell me what is sil and where to connect the eyes of the robot to the body please
Pranjal Joshi (author)  msadashiv2 years ago
the eyes i.e. sensor have to connect at front part of robot... u cant connect it 2 back side because it causes problems and complications while turns..
refer the given images carefully..!!
sunnyy2 years ago
nice project. . can u please tell me the complete details that how it makes and how it works because i determined to make this project as my final year project of computer engineering. . plzzz tell me about this
Pranjal Joshi (author)  sunnyy2 years ago
when photodiode recives light frm white floor it activates the op-amp and output from op-amp activates transistor.
trans. acts as on-off switch to the motor. when photo diode on black path it switch offs opamp i.e. 1 motor and 2nd motor is runs due to sensor on white floor..
on turns due to rotation of only 1 motor robot can also turns..
bilalasd2 years ago
Nice project!!... can you explain a little how it works please. Im kinda new to all this
Thank you!
jimmy5582 years ago
Can U Tel Us Why U Had Put Some Gray Spots On Black Strip..??
Pranjal Joshi (author)  jimmy5582 years ago
ohh..!!
its a black tape and gray dots are actully name of company of black tape..!! :) :)
kiberkotxxx2 years ago
NICE :)