Easier Approach to Electronic Projects

LFR Using Just 555 Timers

This is Simple and cheap approach to Line Following Robot, This do not have any micro controller but just a simple basic Circuit on three 555 timers. It has a good efficiency on following all kind of curves. This Robot is no more than 1000PKR. To make a reliable and well functioning robot, you just not need Electronics Skills but also a little Mechanical too. Having a Electronics mind, the most difficult job I felt in making this robot was Tires which would fit Properly in my motors and the Structure of Robot. For these stuff I accessed my University’s Lathe Machine for tires and a Wood Work shop to make the Structure.

Parts List         Transistors      555 Timer ICs
  1. 1k x (4), 4.7K & 180R
  2. Potentiometers 10k x (2)
  3. 10uF x (3)
  4. LDRs x (2)
  5. Bright White LEDs x (2)
  6. n4148 Diode 
  7. Transistors BD3904 x(2)
  8. 555 Timers x (3)
  9. DC Geared Motors (2)
  10. 9v Battery

Here are some DC Geared motors which I personally recommend. Gearing box in the DC motor is very important in this project, or I can say in most of LFRs. The main reason is torque! Which is essential to carry the weight of the entire robot. Moreover, Gearbox also allows us to have control on the RPM(Speed) of the motors. If lets say RPM is too fast, than the sensors will get very less time to understand the difference between black/white colors and turn on/off motors. Therefore, while selecting your DC motor please take a look at its technical specifications before ordering online.


Circuit Diagram:

Does this circuit looks difficult to you ?! wana go for a simpler than this ?! Click here to see my Differential Drive based Line following Robot made on just BC108 Transistors.


Bread Board Arrangement:

This is complete Diagram of whole circuit for Line Following Robot, but I have not shown the connections for LEDs, So for that, you will have to connect two LEDs in series of 1k resistor with +ve and -ve of this circuit.

Dont feel that this is any difficult circuit, its very simple if you notice that Both 555 Timer circuits(others except center one) are exactly same. So you actually need to built the following two circuits.

Our motors are not directly connected to the outputs of 555 Timer, but a transistor is used as a switch. The Pin Configuration of this transistor is (1)Emitter, (2)Base & (3)Collector

I name this Part of the Circuit as Motor Driver Circuit, Now this is a circuit in which our DC geared motors are to be Hooked up, So wee need to make two circuits like this one in which The pin no 2 (Trigger) is given input from the Center 555 Timer Circuit In the above images

It is configured as monostable, that means when they are triggered they give a pulse on the ouput pin which is then connected to transistor as switch circuit for motors

Now this is the Circuit which gives Output to the twin circuits (Motor Driver Circuits)

This is configured as an Astable Square wave generating a  trigger pulse with a frequency of 1kHz

Where the width of the Square wave is determined by the 4.7K resisotor and 10mF capacitor in this circuit


Sensor part:  This is the most important part of the LFR, because it has the sensor which guides the robot to move on Line and donot leave the track EveR !  These LDRS are the eyes of the LFR.

As you can see i have kept long wires which i have later connected to circuit, the reason for taking long wires is to be free of placing this strip sensor board anywhere suitable to structure and for perfection.

The LEDs in this part, are all the time ON. The reflection of LEDs is sensed by LDRs. When LEDs are on black area there is no reflection and LDRs are dark (Motors Run) but when LEDs see white line the LDRs are shone some light and hence trigger the Motors to turn off

In my Structure as you see in Video, My sensor part is not fixed. When you design your chasis of Robot, must have any technique to fit the sensor part Fixed in the structure. Make sure to keep sensor part height to be as lowest as possible for higher efficiency 

Movement Principle of LFR:

Must Use DC geared Motors for this Circuit, Because ordinarary motors do not have enough torque to carry the weight of the structure

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