Picture of 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

Picture of 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.

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AkiraNic1 year ago

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?

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.

are u connected left side motor to right LDR or left LDR??
how wil it turns if light only falls on one side of LDR??
dynaso73 years ago
Hi, can you show me how this robot work ? (Share the video)
And this robot does not need wheels?
thenmozhi6 years ago
can u plz explain me how this circuit works
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???
dunnos (author)  Gerrles4 years ago
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?
Gerrles dunnos4 years ago
yea i know how transistors work and for the circuit board i mean that do u need a bread board
Gerrles Gerrles4 years ago
can u post some pictures of connecting the transistor and stuff if u do that will really help
dunnos (author)  Gerrles4 years ago
what exactly do you want to see? do you want to know wich pins go where?
Gerrles dunnos4 years ago
yea which pin goes where thnx
dunnos (author)  Gerrles4 years ago
Let me make this a learning experience:
for the pins of the bc557c: click here

for the pins of the bc547c: click here

Gerrles dunnos4 years ago
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
dunnos (author)  Gerrles4 years ago
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?
Gerrles dunnos4 years ago
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 http://www.instructables.com/id/How-to-Build-a-Robot---The-BeetleBot/ step 16
dunnos (author)  Gerrles4 years ago
I already built that one, I really liked that build :) I suggest the beetlebot V2.
Gerrles Gerrles4 years ago
so if u just put picture of which pin to which pin would be fine and my teacher keeps saying im not talented
dunnos (author)  Gerrles4 years ago
What a nice teacher you have -_-
dunnos (author)  Gerrles4 years ago
you can use a breadboard if you want, you can also buy the kit or do it freehand, whatever your preference is.
Gerrles4 years ago
HELP i dont know how to read the diagram
cupnoodles24 years ago
Hey wsup i was wondering u asked for 4 transistors but u only used 2 on the diagram. Is there anything wrong with the diagram or is it just me that i cant understand it? thanks for replying
srinandhana5 years ago
could u explain the circut ahd u can give the source code.......for light following robot
srinandhana5 years ago
could u explain the circut ahd u can give the source code.......for light following robot
salahaddam5 years ago
 There's a BEAM type similar to this at

freerunnin15 years ago
i got this from maplin and made it in 4 mins :P lol
AndyGadget5 years ago
I've just linked this Instructable from 'answers' so here's a bit of info as to how the circuit works . . .

The variable resistor should be adjusted so the motor is just below the point of turning on in normal light.  When a light is shined on LDR1, it's resistance drops and a current begins to flow in the base of T3 causing it to start to turn on and draw a current from the base of T1 (through R3).  This in turn, causes a larger current to flow through T1 and into the motor M1.  The LED (LD1) will also begin to light up.  The brighter the light on the sensor, the more the transistors will turn on and the faster the motor will spin.
The full robot is two identical circuits, and each half turns on the motor on the other side of the robot, so if, for example, the LHS sensor sees light, the RHS motor will spin and the robot will turn towards the light. 
If the light is equal on both sensors, both motors will turn and the robot will go straight towards the light.

Kiteman6 years ago
I've tidied up the keywords for you, and moved the project into Tech rather than Craft.

(One thing you forgot to mention is where other people can buy the same kit.)
dunnos (author)  Kiteman6 years ago
thank you for doing that, i am quite bad at keywords. and i must've been half asleep putting it into craft O_o

i put in where to find it in step 4
dunnos (author)  dunnos6 years ago
oh, and could you tell me what you thought of this instructable? please? =]
derbert dunnos5 years ago
now the video's gone, it's not an instructable.
dunnos (author)  derbert5 years ago
OMG could you just SHUT UP!?
Kiteman dunnos6 years ago
It's OK - a bit lacking in actual instructions, though. Tips on soldering, ways to position components, what needs trimmed to size etc. would have been useful.
dunnos (author)  Kiteman6 years ago
yes, but soldering can be fouund in other articles, i have given some tips but i guess not enough(positioning) and i can't quite get what you mean by trimming to size

but thanks, i like it when people can say these kind of things without going all: this sux and this is **** and you *** ****** and**** know what i mean? (of course not on instructables due to the be nice policy but still)
dunnos (author)  dunnos6 years ago
there, i have some more about positioning. you could check it out, if you have the time (hint hint) =]
Kiteman dunnos6 years ago
That's better - these things come with instructions, but there's always something they forget to tell you.
it is a good kit tho :) 1st time i actually understood what the circuit was doing, it was that simple :3 great for beginner robot makers that actually want to understand the basics and not just buy a kit that is far too advanced for them to know whats going on :P especially if there is programming involved ;)
Kiteman dunnos6 years ago
When I said trimming, I have seen the kit, and it's clear that some components need their leads trimmed to size and others don't.
dunnos (author)  Kiteman6 years ago
.. i believe that lead trimmming is part of the soldering, did you EVER when soldering on a pcb let the leads stay theyre original length?
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