INDEX

Line Follower Circuit

Figures shows a simple circuit diagram. The basic principle is the switching action of power transistor. When LDR is in white, there is reflection from the ground and the resistance of the LDR is very less and Ve >.8V makes the transistor to saturation. When LDR is in dark the LDR resistance become high and Ve<.5(adjust like that) which makes the transistor to cut off and the motor stops. The 10Kpot is adjusted in such a way that transistor will be cut off when it is white strip and cut off when it is in black strip.This circuit is made for both motors.
DISADVANTAGES:
1. Here there is normal stopping occurs with motor. We should require breaking to stop motor abruptly.
2. The motor speed should be limited, because if the speed is higher then robot will cross line due to inertia.
3. There is some time take to stop motor in 'stopping'(braking is other ).
4. Even though it sensed black, then also it crosses the line due to high speed, therefore speed should be limited.
5. Maximum speed of the robot obtained by the robot using this circuit will be very less. I think maximum up to 20cm/s and that to depend upon the way.

Now let's go for a circuit which uses breaking of motor