Introduction: 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.
Step 1: 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
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!
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
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!
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
Now connect a 0.01uf capacitor between the pins 1 and 5 of both the chips.
Step 7: Sensors
The sensors used in this robot are nothing but simple LDRs. LDR is a kind of resistor whose resistance varies according to the intensity of the light falling on it. Connect the LDRs between pins 1 and 2 of both the chips. You can connect LDR either way as it does not have polarity.
Step 8: Conclusion
Now, last but not the least. Connect your motor between pin3 of the chip and negative rail of your breaboard. Do the same with the second chip. Its all done! You have built a light seeking robot yourself! Connect a 9v battery and shine a torch over the LDRs. You will notice that the motors run! Place the motors in such a way that the LDR controlling it is in the opposite side. The LDR controlling the right motor must placed to the left
Step 9: Troubleshooting
If this project is your first electronics project then you may have some problems. Here are some tips to ensure that your robot works best.
1. Make sure that your connections are correct before applying power. (Use the schematic diagram because as this is my first instructables I was very excited and took the photos in a hurry and there might be some errors in the connection.)
2. Confirm whether your components are working properly before using them.
3. Use a low power consuming motor.
Enjoy!
57 Comments
6 years ago
sir I want schematic diagram for making lfr using NE555.plzz help me.
Reply 6 years ago
Schematic diagram is already attached to this instructable.
Reply 6 years ago
thank you sir.
7 years ago
sir this robot follows which coloured line dark (black) or bright (white)
and how to adjust sensitivity of LDR
7 years ago
You can read this. The circuit is similar.
http://www.circuitdiagram.org/light-activated-rela...
7 years ago
I am sure the answer to this is pretty simple since no one asked, but why is there a resistor instead of a capacitor? I have checked the astable mode circuit diagram and there is a C where the LDR is. I find that odd, shouldn't it be a Light Dependent Capacitor instead of a resistor (if such thing exists)?
8 years ago
HOW CAN I CONTROL THE SENSITIVITY OF THE LDR? WHERE SHOULD I USE POT?
Reply 7 years ago
You can use some resistor in parallel with the LDR. Try experimenting.
8 years ago on Introduction
i am a new starter at the robotics and i am really confused between which capacitor to buy because there are a lot of capacitors with different voltage values so plz can anyone send me a link of required the capacitors for this project on ebay.you can mail me the link on the below given id
zenilmehta@gmail.com
8 years ago on Introduction
Can you post a video of the robot in action? It would improve your I'ble and besides that, I' curious to see how it reacts to light... :-)
Reply 8 years ago
Sorry! I have already used the parts in this robot to build others. I will try my best.
8 years ago on Introduction
Hi, could u plz tell us how how did you get the values of the capacitors and why did you connect them in that why and plz show any calculations u did.
Thanks alot
Reply 8 years ago on Introduction
There was not much math involved in this build as I used an existing circuit with some very little modifications. It was a light activated led circuit where in place of led I attached the motors. The motors that I used needed very little power. If not then I would have added a transistor.
Reply 8 years ago on Introduction
thanks for your reply .
may i know why did you use 2 10k resistor. and is your 555 timer acting in an astable mode?
Reply 8 years ago
Yes the chips are in astable mode to provide pwm for the motors.
8 years ago
Sir i am using a 12V dc motor at 300 rpm. Problem is that there is not enough torque to push the robot. Can i use a transistor(til31c) to amplify the voltage
Reply 8 years ago
Try using a lower power consuming motor. If you want to use a high power motor, check the datasheet of the transistor that you want before using it or simply use a motor driver.
8 years ago on Introduction
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 :)
Reply 8 years ago
I never designed a PCB for this robot. It will take some time. I will try my best and contact you soon.
Reply 8 years ago on Introduction
Sir, have you done it? my project submission date is almost getting over :(