555 timer based light seeking robot

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.
Remove these adsRemove these ads by Signing Up

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.
C.V.Hariharan (author) 1 month ago

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


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 ?

Sorry , fixed it !
C.V.Hariharan (author) 1 month ago

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

cian h r5 months ago
how does this actually work? what state are the 555 timers in? could you answer asap please
C.V.Hariharan (author) 11 months 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.
botgames11 months 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.
instead of using 2 555 timers, can you use 1 556 dual timer ?

Get More Out of Instructables

Already have an Account?


PDF Downloads
As a Pro member, you will gain access to download any Instructable in the PDF format. You also have the ability to customize your PDF download.

Upgrade to Pro today!