555 based balancing bot

This post on Reddit by [superangryguy] caught our attention today. He’s put together a video explaining the basics of how to build balancing robots, focusing on a 555 timer based one. He’s got two main versions, the 555 based one and another that is based off of two transistors. He says the 555 based one is much easier to build. This has all come about due to the upcoming 555 timer contest. if you go to the Reddit post you can get schematics for both versions as well as a sneak peak at what he plans on building for the contest. You can see the video after the break.


  1. SomeEvent says:

    I think you may have just upset a lot of builders who struggle to do this with a $100+ worth of micro and sensors.


  2. werza says:

    Analog beauty.

  3. Pii says:

    You got that right!
    Nice stuff.. you guys have any idea on what else to build for the 555 timer contest?

  4. Ryan says:

    I will be baffled if people manage to complain about this project.


  5. mccoywm says:

    @Ryan You’ll be baffled if people complain? Welcome to HaD :p

    But yes I had to build one for my final project in EE, with micro, h-bridge, reflective sensor and I must say this is very impressive. We didn’t put in the derivative but it clearly would have helped. Again, very impressive.

    Video of ours

  6. 1337 says:


  7. zool says:


  8. Mike says:

    Could you add another servo/wheel pair on the other side? Would that somehow change the circuit. I would like to build one with two servos.

    Also, why do you have 3-4 wires coming in on the tether? It looks like the circuit only shows the power source as missing. Could the battery pack be mounted with another servo/wheel pair to eliminate the tether?

    Very nice control – can’t believe you got that nice of a fluid response with photo resistors.

    Nice Job

  9. andrew says:

    freakin awesome!

  10. fluidic says:

    IIRC a similar method is sometimes used for signal lock-in.

  11. nice hack!

    BTW this might also work with a passive hall sensor as well, at least in theory.

    If you haven’t submitted it for the 555 contest, please do so :-) maybe under “Most obfuscated hack” ?

  12. o says:

    You could have done this with a 555 and two transis- Oh wait. Nevermind.

  13. lamer says:

    is there an arduino bootloader for that

  14. vin says:

    analog power, you won’t need to write any code and not worry about the complexity of the algorithm for that matter.

  15. vin says:

    yeah the LDR are working much better than expected..

  16. Necromant says:

    I guess, only Chuck Norris managed to run arduino on ne555 =)

  17. That is a great video and excellent explanation.

    One question.
    If you shine a light source on one side will it attempt to travel towards it?

  18. Dino says:

    LOVE the simplicity. Great application of the 555. :)

  19. IACN Engineer says:

    I love your description of derivative. Perhaps you need to decrease your gain if you want that higher derivative as well. The lower gain with the higher derivative would be able to stabilize.

  20. Filespace says:

    The only think i can think of is making a mini segway out of this thing. and strapping a little white mouse to it and its the next viral youtube video!…lmao thats just so funny..

  21. cde says:

    You’ve reduced the segway to a 10cent offtheshelf part.

    Lawsuits, engage!

  22. wow this is awesome! who needs microcontrollers anyway :-)

  23. mic says:

    555 = > chuck norris. Is there anything you can’t do with those?

  24. Alex says:

    Yep, elegant. Very neat post.

  25. Bob Johnson says:

    Could someone explain what the purpose of the 90 degree opposed light sensors is? Is that how you’re sensing the balance? By seeing how the light changes and trying to get it back to the original value? Wouldn’t that mean this hack wouldn’t really work for a robot that moved because the lights/shadows hitting the photoresistors would be constantly changing?

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