Let's Make Robots!

Little 8

Very cheap but fun little beginners robot. It think' it has a brains within a Picaxe 8


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Edit: Check out this nice clone: http://letsmakerobots.com/node/8386

From building big, nasty, with large shovel, 2 cores, multiple sensors, soundsystem etc, I got tired of that.. and decided to see what fun I could have with a little Picaxe 8 on a board ($16, total prize for robot is about $40).

Version II of this fella here: http://letsmakerobots.com/node/101

I have since recieved some interest in how to build this extremely easy and cheap robot, and so I hereby transform this post to a small and simple tutorial:

Shopping list:

Can be bought from Picaxe:

You can get this from anywhere:

  • 1 9V battery
  • Some sticks and something to cut them
  • Screwdriver
  • Soldering iron and led
  • Some pieces of wire and something to cut it with
  • Some different types of glue or tape etc
  • a table-tennis ball and a knife to cut it
- And then you need some motors with wheels. I recomend these, used in my robot.


I like the challenge of only having 8 pins and 128 bytes of code etc. But be aware; you get a funny robot, but it is blind, can only sense a bumper in front, and you really do not have much memory in it etc.

What I did after building this, was i set it up with Easy Radio serial wireless input on the only pin left for anything. This made it possible to control this little robot by another robot, which opens new windows etc.

Some friends and i in our local club also had a contest of making it draw the number 8 on a piece of paper with a marker glued to its back.. Good fun little fast and chep robot!


A stick, some switches, and a sliced up table-tennis-sized ball for "the third wheel"


To get the 9V down to 5V, I use a voltage regulator.

I was just mounting with some glue, the strips just tohold things in place..


An angle grinder may look like an extreme tool for such a small job - but I use it quite often. Just turn it on, hold it steady against something, and anything you stick in there is just vanishing, nice and smooth - compared to cutting such small parts. I also use it for acrylic (Plexiglass), again it is perfect to make little cuts and markings.


Just follow the instructions that comes with the board - it cannot be more simple, hook up the 2 motors.

The motors I recomend are incredible! Fast and strong, even though I only feed them 3.5V due to the 1.5V drop from the Motor Driver. So I actually had to make a "tale-bumper" (red square) as it was lifting the front a little too much :D With the bumper on it turned out quite cool, as it is just as capable of navigating on only the rear-wheels.. there is nothing else but a glider in front anyway.


All needed now is some code and the battery.

TIP: Get rechargeable batteries (and a recharger) - Or you will soon have used as much on batteries as on the Robot itself!

REMEMBER: If you make anything like this, to take a picture and show me :)

Here is the code used in the robot on the video. Don't mind that the names of the sub-routines does not make sense to you. Fact is that nothing in this code makes much sense, it was just the fun I had at the time when I shoot the video :)

I will have a closer look at this soon, but on request, here the code from the video:

symbol fw = 20
symbol bc = 200

b0= 175


random w5

for w3 = 0 to w5
if pin3 = 1 then
gosub bum
end if
next w3

b0= b0 +1
random w5
if b0 < w5 then goto hest

random w5
if w5 > fw then
high 1 low 0'ForwardRight

random w5
if w5 > fw then
high 4 low 2'ForwardLeft


random w5
if w5 > bc then
high 2 low 4'ReverseLeft

random w5
if w5 > bc then
high 0 low 1'ReverseRight

goto dav

w4 = 32212

high 2 low 4 high 0 low 1'Reverse
pause 300
if b0 > 175 then
high 1 low 0'ForwardRight
high 2 low 4'ReverseLeft
high 4 low 2'ForwardLeft
high 0 low 1'ReverseRight
end if
pause 300

b0 = 175

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I live in the UK and am relucatant to ship in those exact motors and wheels from the american website. Can you get the same motors (or similar ones in tems of size and power) from a UK source? :)

A couple of things I took from just looking at this today:

 - I like the way you attached the wheels to a small piece of wood with glue and zip ties.  I've been using just double sided tape myself, which is ok, but not particularly strong.  I think the zip ties would help here.

 - The 9V battery....  For some reason, even though I've got a 9V kicking around in my box of bits, it never occured to me to use it.  I just used my 3xAA battery pack instead and was feeling it was way too heavy for this.  That'll be my first change to my bot, I feel :-)

 - Finally, the voltage regulator.  I have 2 but haven't used them yet.  I'll have to try them out now!



i was wondering, the code on this page is to make the robot advance and if he hits something it backs up and turns to a side depending on witch site it hits first right ???

The code on this page makes not much sense. Nor does it to try to program a robot with such a tiny brain!

There simply is not enough room for any programming that would make sense, so this is the second best; Some random stuff that makes it go around & push stuff, not very orderly :)

It is what is used on the video.

i am new to this site.i wanted to know where could i get axe 023and programming editor in india.please reply soon.

Hi, and welcome.

Do you think anybody who is going to answer will read your post and then answer later? No? I do not think so. I think that when somebody that is going to answer has read your question, I think they are answering right away, and not after some time.

Why am I writing this? Well.. You write "Please reply soon". Can you see the logic I am trying to show you? 

Anyway, for an answer, you can just do a serach on the site, I have done it for you, and see what I found: http://letsmakerobots.com/node/213


 you can only ask anyone in communication dep. at any engineering faculty in india , they use these things quiet often , so there's shops for them to buy that stuff


hi , i am a very beginner one , and i haven't used to make robots with that microcontroller things , so  if you please provide more instructions on how to use the microcontroller thing , i mean how to connect wires and stuff like tha , i don't want end burning the chip :D
RTFM, or the Start here project, see top menu.