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.
Step 1: 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… ï
Step 2: Circuit 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:
Step 3: Making the PCB
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 5: SENSORS: the eyes..
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