Let's Make Robots! | RobotShop

555 Timer Photovore Robot

Searches for light

This is a simple robot that I made for my cousin, it only uses 2 LDRs, 2 geared motors, and a 555 timer IC.

I reused a Tamiya Tank tread kit and gearbox for locomotion. All powered by 4 AA batteries. The batteries, IC, and switch are all housed in an Altoids tin.

Not much more to say about this robot (Sorry OddBot) 

Requested pictures: 

Schematic I found from the internet.

There's not much to see on the inside because i DeadBugged the 555 Timer.


EDIT: As of July 25, 2012 this robot no longer belongs to me. It has been shipped off to Chicago to give company to my cousin.

Comment viewing options

Select your preferred way to display the comments and click "Save settings" to activate your changes.

I think, if I got the schematic right in my head, you're using two 555 timers in astable mode to generate the motor PWM and the LDRs vary the RC time constant to change the pulsewidth of the motor PWM.

Am I right? :P

I'm using a much simpler method. One 555 timer, two dc motors, not servos. a voltage divider output from the ldrs is fed into the 555 timer. I'll post a schematic soon.

Yeah I was thinking of two geared DC motors but only one 555? Now I'm interested in the schematic :)

Anyway nice and simplistic and it does it's job

Thanks for posting the schematic. 


Yep, we need schematics, video, a look inside the "box". There is so much ti say about this robot.... :) (need a purpose to dig out my 555's)

Is this the correct way to attach the potentiometer? (Ignore the switches in the begining ;) )


The photodiodes replace LDRs (needed IR not "White Light")


can that robot work with 3 AA batteries??

That 4 rechageble AAs won't work well if their voltage is too low. The motors seem to run fine, but the light seeking behaviour is impaired. I wouldn't recommend 3 AAs