Little One - the smallest robot in my garage

This is the smalest robot, that I have ever built. On one of the websites I found picture of other robot, that become an inspiration for me. Unfortunately, I didn't achieve such small scale but still I'm proud of final efect.

Previous version

Presented version is not first one. It is a second one. In first one its weight point was very high what made him very unstable and his brain was simple 4093. Generator build on one gate generated square wave and sent it through IRED diodes coming from old, ball, PC mouse. When robot came closer to some obstacles and reflected beam hit the photodiode, then this motor stoped. That made robot to turn. As you can see, it wasn't the most inteligent beast ;-).

Current version

As a improvement, I decided to give him a few additional brain cells. I replaced 4093 with Attiny2313. This let me to implement a better way to control motor speed and obstacles detection. Eyes are the same but triggered by microcontroller.

We can find here four modules:

  • control
  • eyes
  • motor control
  • power supply

Control is realized by mentioned device Attiny2313 with all necessary components to its proper work. Code is written in C and uploaded to device by ISP connector. It is not the final version, but at least the newest.

Eyes contains three gates. U3A with elements R19 and C7 makes square wave generator with frequency given by equation:

f = 1 / (2.3 * R19 * C7)

This generator starts to work when logic one is on his input. Wave from its output controls transistor Q1 switching on and off IRED diodes D3 and D4.

Didoes D1 and D2 are kind of eyes looking for reflected, infrared beam. Signal from voltage divider built from diode and potentiometer goes to input of a gate. Sensitivity is changed by PR1 and PR2. When obstacle is detected, signal from gate output is delivered to microcontroller and interrupt occur.

Motors are controlled by low-power H-bridges. They are documented very well in the Internet so I will not describe them here. One is worth to mention, that thanks to them I can change rotating direction without using relays. Advantage of using microcontroller is I didn't have to use any logic to protect those bridges before combination of "11" on its input (this would cause a short circuit). This let me to earn a place on a board.

Mechanic part

Details are shown on pictures below. Body is made from PCB. It is quite good material, because after cut out all pieces, it can be connected by soldering. I was trying to figure out such way of mounting, that let me to easly change parts without need of disassembling a half of robot. More or less I managed.

Version 1.10

Version 1.20

And on the end a few emails that I recived during last years, after I put it on one robotic website:


"hello, I am an aspiring robotics fan and I was wondering if you could send me instructions on how to build this what looks like a relatively simple robot . thanks in advance. Robotics fan"


"Hi Peter Krzyzaniak,

I am Vivek. I saw your robot " the little one". I am interested in doing a small robot like yours... i went to the site you stated there. i cannot understand the language... so send me the details and specifications as soon as possible..."

~yonas rahendanu

"Hi Peter, I'm from Indonesia.

Yeah I'm a beginner. I start to learn mechatronics. I'm 25 years old, and now I'm working as a CNC machine programme, so I think, I should learn about mechatronics. and for the experiments, I want to start to make a simple robot, but I have a little problem to find a servo motors and colar cell here (in Indonesia) I dont know where I can find it. Could you help me?

thank you verymuch Peter

I look forward to hearing from you again




I saw your robot(LITTLE ONE) on web and i am interested in building as robot for my project,so can you please guide me in building it. i am waiting for your reply

I am Anurag Wankhede from INDIA , electronics engg. student."


"Hi Peter,

I saw your robots on your site www.robotics.com/robomenu/littleone.html. I must say all of them look really good. I specially liked the Little One. I am from Ideawicket.com, it's a site for innovators to showcase their innovations and projects, invite feedback from the viewers.

We would like to feature your robot on the site's homepage for some days because of their high quality. If you are interested, please do let me know. You can go to the site, register and post them. The site is easy to navigate but do let me know once you post them so I can feature them on the home page.

Hoping for a positive response from you and hope to see your robot on Ideawicket soon."

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