Easy Robot: Light Follower





Introduction: Easy Robot: Light Follower

No programming or microchips!

Robots, the most awesome thing there is, especially when allot of people can build it!
I got this robot from a friend as a present. thank you Rudolf.

Anyway, this robot uses 2 Light dependent resistors to sense light and drive toward it.

Soldering iron->hot->hurts

That said, lets start

the reason this is green: the battery's i used are rechargable, one battery can load 1000 times so i save 1998 battery's in this instructables

PS: you have to have SOME electric knowledge for this.

Step 1: Electrical Materials

R1-4 4 100 ohm resistor

R5-6 2 220 ohm resistor

SW1 1 Switch

RV12 2 10k variable resistors

T12 2 Transistors BC557C

T34 2 Transistors BC547C

LD12 2 LEDs

LDR12 2 Light Dependent Resistors

1 IN4007 Diode (note: can be replaced by a paperclip, it supports the wheel XD)

*Note: I got this as a present from a friend. Some of the parts can be different, I dont know.

Step 2: Rest Materials

Box to put everything in and a piece of cardboard so you pieces dont go flying / PCB**
Some wires if you dont have a PCB.
Some electric components
Battery holder
Some motors, I got some open chassis motors
Soldering iron
File / sanding paper
A small screw
Something to make the motors have more grip (heatshrink?)

** : I dont have a digital version of the pcb , as I told you I got it from a friend. If someone has the tools to make a digital version please do.

Step 3: The Building Of.

1. resistors
2. transistors
3. switch
4. LEDs, these are supposed to bend a bit (looking like bug eyes) i bent them about 90 degrees.
5. light dependent resistors, these are supposed to point forward. (solder them on and then bend them until they lyon the pcb.
6. variable resistors point them forward and next to eachother, that looks fun
7. AAA holder
8. motors, file them down so you can solder/glue them to your pcb/box. put these under an angle so the axis of the motor acts as a wheel
9. put some heatshrink on the motor. this wil get some extra grip and makes it go faster.

Step 4: Operate It

When I just finished the robot i didn't quite know what to do with it, yes i knew it drives towards light but then what do the variable resistors do?

Turns out that the resistors say how sensitive a light dependent resistor is.
if you turn the one close to the left LDR then the left LDR will become less sensitive. and thus the RIGHT motor will not turn as fast.

PS: you can get this kit at:



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    49 Discussions

    1) is there a way to build this without transistors?

    2) If I connected the left LDR to the left motor, and the right LDR to the right motor, is it going to turn to the side with less light?

    3) Will the LED interfere with the LDRs?

    1 reply

    4) Is there a way to combine this with BeetleBot?

    5) How to make it go slower? I've seen one in a video and it runs like mad. I wanted it to be slow.

    Hi, can you show me how this robot work ? (Share the video)
    And this robot does not need wheels?

    just lok at the circuit and u should be able to see how it works ;) i knew nothing of circuits til i bought this very kit and once i examined the diagram i understood what was going on :)

    can u help me i dont understand the diagram and do u have to have that circuit board???

    I can try to explain how the circuit works... What do you know about electronics right now? Do you know how transistors work? And what do you mean by do you have that circuit board?

    yea i know how transistors work and for the circuit board i mean that do u need a bread board

    can u post some pictures of connecting the transistor and stuff if u do that will really help

    what exactly do you want to see? do you want to know wich pins go where?

    Let me make this a learning experience:
    for the pins of the bc557c: click here

    for the pins of the bc547c: click here

    u know im only 12 im doing this for my project and i dont know the bc557c or the bc547c because my PDF donesn't have english

    What do you mean with: my pdf donesn't have english? you mean you can't read an english datasheet? Or is adobe reader not cooperating?

    also, do you have the kit or are you doing this on a breadboard?

    flat side facing you:

    BC557C: the leftmost pin is the collector
    the middle pin is the base
    the rightmost pin is the emitter

    Same goes for the BC547C.
    On the image the flat side is the bas
    the line going right and up is the collector
    de line on the right downside is the emitter.

    Can you figure it out now?

    adobe reader is not cooperating and i dont have kit or breadboard. Im building it free hand and not really, can u try the diagram from https://www.instructables.com/id/How-to-Build-a-Robot---The-BeetleBot/ step 16

    I already built that one, I really liked that build :) I suggest the beetlebot V2.

    so if u just put picture of which pin to which pin would be fine and my teacher keeps saying im not talented