Instructables
Picture of 555 timer based light seeking robot
I have always been fascinated by robots especially one with the wheels because they are cheap, easy and fun to make and play around with. Recently I came across a circuit in one of the books. It was a light sensitive led circuit based on 555 timer ic. I modified the circuit just a little to make a cheap light seeking robot. Let's see how i did it.
 
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Step 1: Materials

Picture of Materials
To build the bot you will need the below mentioned components.
1. 2x 555 timer ics
2. 4x 10k resistors
3. 2x LDRs (Light Dependent Resistors)
4. A breadboard if necessary
5. Some wires
6. 2x motors (with wheels)
7. 2x 0.01n capacitor
8. 9v portable power supply

And you may also need a messy workbench.

Step 2: The Schemetics

Picture of The Schemetics
The schematic diagram of this robot is very simple to understand. As I had mentioned earlier I just modified a circuit from on of the books to create this one. Make sure that the motor you use DOES NOT draw a lot of current. 

Step 3: Chips On The Board!

Picture of Chips On The Board!
Insert the ICs as shown in the figure. There will be a small notch or dot on every 555 timer ic. Make sure that the dots on both the chips should face upwards if you are going to build the robot as per the breadboard layout given in this instructables. Connect pins 8 and 4 together. Then connect pins 6 and 2 together.

Step 4: Power Source Layout

Picture of Power Source Layout
Connect pin1 to the negative rail on the breadboard. Connect pin8 to the positive rail on the breadboard. Do the same with the second chip.

Step 5: Resistors!

Picture of Resistors!
Now the most important part. Connect a 10k(brown, black and orange)resistor between the pins 8 and 6. Connect one more 10k resistor between the pins 7 and 6. Do the same with the next chip.

Step 6: Capacitors

Picture of Capacitors
Now connect a 0.01uf capacitor between the pins 1 and 5 of both the chips.
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sabbir.emon12 days ago

SIR, thanks a lot. Will you please give me a working PCB layout for me ?? I have done it for my midterm project, and For final term, it is required to implement the robot with pcb. thanks :)

C.V.Hariharan (author)  sabbir.emon11 days ago
I never designed a PCB for this robot. It will take some time. I will try my best and contact you soon.

Sir, have you done it? my project submission date is almost getting over :(

C.V.Hariharan (author)  sabbir.emon6 days ago
When is the submission day? I am out of access to computers right now. Why don't you read some online sources and try till I can start designing?
kkhanna26 months ago

how to connect the battery.....pls tell asap

C.V.Hariharan (author)  kkhanna26 months ago

sorry ,can you explain it further?

thanks but problem solved but giving rise to new problem that the motors are making a very low noise.....but wheels not moving can this be an issue of battery cuz battery is 5v

C.V.Hariharan (author)  kkhanna26 months ago

how many volts does the motor need? be sure to check the value of components as well.

I have used the same values of component that you mentioned....

kkhanna2 kkhanna26 months ago

between 9-12 v.....and.....I tried a new battery too...but still motor sounds when I flash light but it doesn't move.....pls help

kkhanna2 kkhanna26 months ago

this is the motor am using but with gear

temp_-1774671833.jpg
C.V.Hariharan (author)  kkhanna26 months ago

try attaching a 100 nano farads capacitor between the poles of the motor and I think 9 volts battery will be good for the motors

am using 0.01 micro farad .....should I switch to 0.1 micro farad

C.V.Hariharan (author)  kkhanna26 months ago

when you here that noise try twisting the motor manually no need of changing the capacitor.

I did try to twist the wheels...but still the wheels move by manual external force only and that too a little bit...

C.V.Hariharan (author)  kkhanna26 months ago

can you upload a photo of the circuit that you have made so that I can analyse it?

see..this...if need any more info am ready to give...but pls solve....it...thanks

temp_-1774671833.jpgtemp_-1249299752.jpg
C.V.Hariharan (author)  kkhanna26 months ago

First we need to figure out whether it's the problem of the motor or the circuit. Try repaying the motor with an led each. Attach a 150 ohms resistor to the led. If the circuit is fine the led should respond to light. Then try changing the motor.

ohk I will implement this......but I did one more thing ....that I used multimeter to measure voltage at motor while flashing light it only showed 0.12 v.....and I don't think that will help it run.....anyway....going ahead with your suggestion......and...implementing it.....will sent the result......thank you

C.V.Hariharan (author)  kkhanna26 months ago

From the photos you have uploaded, I think the resistors might have been not wired correctly. I might be wrong as photos don't focus just on the resistors. Try checking them and make sure all the components work. Connect one pole of the motor to pin 3 and other to the ground.

Hey can you please recommend me a DC motor which doesn't draw a lot of current or the motor you used or any link.......cuz I when I replaced motor with led circuit worked fine....... Thanks in advance
C.V.Hariharan (author)  kkhanna24 months ago

Check these. These are the motors that I use.

and capacitor you used is 0.01 uF or 0.01nF......will the robot work with either of these capacitors........thanks in advance
Hey can you please recommend me a DC motor which doesn't draw a lot of current or the motor you used or any link.......cuz I when I replaced motor with led circuit worked fine....... Thanks in advance
Hey can you please recommend me a DC motor which doesn't draw a lot of current or the motor you used or any link.......cuz I when I replaced motor with led circuit worked fine....... Thanks in advance
Hey can you please recommend me a DC motor which doesn't draw a lot of current or the motor you used or any link.......cuz I when I replaced motor with led circuit worked fine....... Thanks in advance
Hey can you please recommend me a DC motor which doesn't draw a lot of current or the motor you used or any link.......cuz I when I replaced motor with led circuit worked fine....... Thanks in advance
ajoshi225 months ago
hey my second ic heat up but i sused crct correctly......
C.V.Hariharan (author)  ajoshi225 months ago
Can you just tell me the precise name of the chip? Along with all the other things written on the chip.
PedroEugenio6 months ago

Great job.. I made it and works really good! :D

C.V.Hariharan (author)  PedroEugenio6 months ago

Good to know! great

PedroEugenio6 months ago
C.V.Hariharan (author) 8 months ago

I am happy to know that you have completed the project.

Congrats!

GreeceFallout8 months ago

Greetings C.V. Hariharan ,

I Really love your instructable and tried making it myself but i used diffrent breadboards so im not sure if i reproduced it correctly, could you please check on my photograph of the circuit and tell me if i've done something wrong ?

DSC_0657.jpg
Sorry , fixed it !
C.V.Hariharan (author) 9 months ago

The 555 timers are wired up in astable mode. This provides something like PWM for controlling the motors.

cian h r1 year ago
how does this actually work? what state are the 555 timers in? could you answer asap please
C.V.Hariharan (author) 1 year ago
For making a line following robot you can use the light follower itself. Just make sure that the LDRs are placed perpendicular to the ground and place one Led each beside each ldr.
The robot would be able to follow a non looping black line on a white surface.
botgames1 year ago
Thank you for your step by step guide. I've been wanting to make a robot for a long time. Your instructable was very easy to follow and understand. And your pictures were very helpful as well. My light following robot works!!! I want to make a line follower now. But haven't found and easy instructable as good as yours to take me ALL the way threw. You should make a line follower and make another instructable. LOL Thanks again!
C.V.Hariharan (author) 1 year ago
Yes, you are right. I would soon like to implement it.
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