I have been in robotics since I was a kid and I am very passionate by robotics. I learn BEAM robotics around 1997-98 and started building robots for a science faire project call "Insectroides" in 2001. http://robomaniac.solarbotics.net ( they change server and the website links does not work anymore it is on Linux and it is CASE SeNsiTIve! ) here is the old one

One of my many robots was the beetle robot, a VERY simple robot that can avoid obstacles on the floor without ANY silicon chip! ( the red ladybug, second picture, is my FIRST beetlerobot )
the red ladybug use a home made PCB carve with a dremel and two playstation motors with rubber wheel from a walkman!


It use
2 - motors
2 - SPDT switch
1 - AA battery holder

I has 16 years old when my uncle showed me the principal of the SPDT switch ( Simple Pole Double Throw). I then took this idea and incorporated the design into the (world famous) beetle robot :P

Now I am 22 and want to show you step by step instructions how YOU can make this simple robot!

here are some videos of my beetlerobot in action!

The beetlerobot in the video is made using a Printed Circuit Board ( PCB ).
This design will be use if I make a kit one day!

Check them all out here!

This Instructable is divided into three parts

- You will learn how to build the robot
- I will explain how the robot works
- I will then teach you how to fix your robot if it does not work ( Debugging )

Don't forget to read the complete tutorial before starting! And remember to wear safety glasses at all time because eye injuries ain't worth the risk! It will happen in a blick of an eye.

Have a great time!

ps- Check out Gareth Branwyn book, I made a one motor walker and he made a complete chapter with my robot!! He send me the book call " Absolute beginner's guide to building robots" A very great book!

Maybe I should write a book...

Jerome Demers aka ROBOMANIAC!

Updated july 2007 - I have added some pictures of the inside of my first beetlerobot. Home made AAA battery holder! I have also added some videos on youtube! http://www.youtube.com/jeromedemers

Updated 22 july 2007 - I added a picture and text on step 19 if your robot does not work :P
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Step 1: All the parts you need

Picture of All the parts you need
Here ar the parts you will need:

the robot parts'
2 - 1,5V motors
2 - SPDT switchs mechanically easy to trigger
2 - AA battery
1 - AA battery holder
1 - plastic or wooden pearl
1 - heat shrink that will fit over the motor shaft

This might cost you less then 10$ cdn.
1,98$ for both motors
1$ for the battery holder
1,98$ for both SPDT switchs
ok ok maybe 10$ is a lot!

I like to buy my stuff here

If you recycle it might be all FREE! Try searching old VCR, PS2, old toys, printer, etc
Back then, I use to recycle EVERYTHING, I got everything FREE, old VCR are very good for gears and something SPDT switchs!!! Playstation have great super good motors, the one that makes the laser move.

the tool to complet the robot
1 - safety glasses
1 - soldering iron
1 - glue gun
1 - wire strippers
1 - side cutter
1 - scissors, knife, x-acto, etc

You need some 1,5Volts motor, not 3V or no event 12V!!
Each motors are powered by a SINGLE AA battery! You will draining your battery if you use bigger motor. You can find them in toys or even at your local dollarrama, in little car, fans, etc! ( beware, they might really suck you battery down )

the SPDT swiths need to be really sensitive! I have order some the order day that where to hard to activated, that might cause some problems and the robot might not even avoid obstacles but rather hug them until death. These swiths are the most expensive part of the robot... around 1$ to 4$ each. The one I use are from Cherry.

You should check http://www.solarbotics.com for some great motors. They even have a SPDT switch in store! I have never tried them but Grant did.

Here is a picture of the Solarbotics switchs in use. The beetlerobot was build by Grant McKee, the engineer for Solarbotics but currently works for WOWWEE in Hongkong ( poor Grant! :P)



Step 2: Preparing the parts

Picture of Preparing the parts
Cut 13 pieces of 2,5inch long electric wire.

ps- cut 14 if you are supertisious.

Step 3: Preparing the parts

Picture of Preparing the parts
Now just remove around 1cm to each extremity of the wire.

In other word, strip the wire at both end.

That is 0.3935 inch to be precise.

After that you need to thin the end of each wire with your soldering iron.
Oups, I forgot to tell you to plug your soldering iron, HAHA you need to wait now!


Step 4: Group picture

Picture of Group picture
Here is everything you need to start building

ok ok I forgot the paperclips and ... what else?


Step 5: Start soldering

Picture of start soldering
solder each wire to your parts.

Step 6: The famous third connection

Picture of the famous third connection
Here is the principal and most important thing about the beetlerobot.

It is call the "third connection"

In you AA battery you have 2 wires that provide 3Volts.

In reality, we only use 1,5Volts for both motors.

How can we get half the voltage? simple, you solder a wire like the picture below.
I solder a 2 inch long blue wire.

simple hey!

don't forget to browse the other pictures to see.

Step 7: Glueing switchs

Picture of glueing switchs
Glue your switchs on the battery holder in a V shape.

Don't forget to put the blue "third connection" wire in front.

I have found a much more efficient way to but the switchs on the battery holder.
You can glue them in a A shape so both antenna cross and will not get stuck in a leg chair.

Step 8: Glueing the motors

Picture of glueing the motors
Glue both motors on the battery holder

Make sure they spin forward...

I have just realise that this does not make any sense at all! :P

Look at the third picture how you can angle out the motors for speed.

Step 9: The back caster

Picture of the back caster
Here you are going to make the third wheel, the back caster using a plastic or wooden pearl.

You can make something fancy or very simple. I took the BIG paperclip.

If you can not find a wooden pearl, you can use the paperclip directly on the floor. It will work but might catch on stuff while rolling around.

Step 10: Soldering the brain

Picture of soldering the brain
Here is the hard part, soldering each wire. Look at this picture and do the same :P

One thing that I forgot to do back then, was to use different colours for the wires to simplify everything.

with some special software I was able to achieve that.

Step 11: The antenna!

Picture of the antenna!
You are going to give your little robot some way to feel the world.

Take the small paperclip and bend them to form some antenna.

Glue them on the metal plate pf the SPDT switchs.

I don't recommend soldering them because you need some aggressive acid-based flux or silver solder. If you don't have any experience in soldering, you will melt them.

I have already solder some using silver solder.

Step 12: Melting some shoes...

Picture of melting some shoes...
Take the heatshrink and shrink them on the shaft of your motors. Use a lighter to attach them.
Yo can put more layer if you want to, different colours.

I even saw some people use hot glue stick on the end of the shaft. They took 1cm of the glue stick and attach it directly to the shaft. BEWARE, you robot wil be VERY speedy and it might destroy itself on the first obstacle it will hit.

Step 13: FINISH!


You made you first Beetlerobot!

Cross your finger, put the AA into the battery holder and but the robot on the floor...

Does it work?

to stop it, you can step on it or simply remove the battery.

You can add some decoration to the robot. I took some big plastic shell find in the 2$ vending machine. I took one half and added sticker!

to debug the robot go to my website
It is in French and you will understand. You made a robot, you can read French now! :P

Oui = yes
Non = no
Est ce que les moteurs tourne? = does the motors turn?
Est ce que votre robot avance tout droit? = does it go in a straight line?

ok ok
I have added other steps to explain more about the robot and a also added a debugging section.

Jerome Demers
You can ask questions in French if you want too.

Step 14: How does it work?

Picture of how does it work?

ps- This robot does not stop the opposite motor when it touch a wall, it REVERSE the opposite motor so the robot will pivote and avoid obstacle the GOOD WAY!

BEAM powered robot will short circuit the opposite motor so the robot will need to push it's way out .

All the drawing where made with PAINT!

Step 15: How does it work? - the motor

Picture of how does it work? - the motor
ok this is simple

The electric motor spin when you apply electricity to it. It will spin clockwise and anti-clockwise when you swap the polarity.

If the robot spin in circle after installing the battery, swap the connection of the reversing motor.


Step 16: How does it work? - the motor and the switch

Picture of how does it work? - the motor and the switch
Here is the complete circuit and one half of the beetle robot brain!

Click the next step to see how electricity flow in the circuit!

Step 17: How does it work? - the motor and the switch part 2

Picture of how does it work? - the motor and the switch part 2
Here you can see what happen when electricity flow through the circuit. Check the second picture.

So you can see that one battery will power BOTH motor when the robot run around your house.

The second battery is only to reverse the beetlerobot when it get stuck. SO this battery will last longer!!

Swap the battery to prolong your battery life and also the robot life.

If the opposite motor does not spin, this mean that you might have a weak battery or simply that the third connection is not working right.

Step 18: Debugging

Picture of Debugging
I hope your cat is going crazy with the robot... maybe your dog?

Does your robot go in a straight line?
Here is a quick fix.

If the robot start rolling in circle you can add a "blob" of glue to the weak motor.

To know the weak motor, simply put the robot on the floor... if it goes to the left add some glue on the left motor. This will make a bigger shaft and makes the left side travel a longer distance and correct the path of the robot.

It does not mean that you motor is weak, it could just be the angle of your motor.

Step 19: Any questions?

Picture of any questions?
I hope everythings work's perfectly for you, if no, ask your questions here!

I took a picture of a special page from the wonderful book Junkbots, Bugbots, and Bots on Wheels by Dave Hrynkiw and Mark Tilden!

Mike Trzecieski wrote that back in 2001 at the Eastern Canadian Robot Games! I got my entire book signed by great roboticist! :D

I got Dave Hrynkiw, Grant McKee, Dave Simmons and his son Kyle Simmons, Scotty Dogma, Ori Barbut, Mike Trzecieski and Richard Weait the creator of the miniball... humm.. do you wonder what is a miniball? Do you want a instructable? :D LOLL

I am missing Mark Tilden signature!!!

Have a great day!

Jerome Demers
Quebec, Canada
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am i correct my motor is moving forward but when push rigth antena my right motor is moving forward again but the left motor is going stop and when i push left antena the left motor is moving forward too and the right motor is stop. My Beetlebot Is Correct? Plsss answer it here's the picture

robomaniac (author)  AngeloMagbanua2 months ago

that schematic is not like the original. That is why it does not work. You are suppose to connect one end of both motors together. Then that connections goes on the other side of the batterie pack.

AlejoC2 months ago

Can I use an LiPO battery, I don't know how can I make the third connection because this battery only have two cables.

robomaniac (author)  AlejoC2 months ago
the answer is yes but I don't recommend you use lipo batterie. If you let the batterie discharge too much it will cause problems that can be dangerous.

you need to connect you batterie in series and then then use the middle connection has the third connection.
AlejoC robomaniac2 months ago
Thanks for your reply, then ¿I need two batteries LIPO? I'm not an expert in the topic but ¿can you send me some image or link to have a clear idea of these? Thanks a lot again, regards!
robomaniac (author)  AlejoC2 months ago

Sorry but since you are not an expert, I can not give more info or else the lipo batterie can explose and burst into flammes if you don't know what you are going. This is serious stuff. It's for your safety and for other people. Go buy some AA batteries and a batterie holder from Digikey.com. You will get that next day for 1.38$ +8$ shipping.


Lukeplayer6 months ago
Where can I find Spdt Switches in the Phillipines?

What is it's purpose? What is the purpose of the beetlebot?

robomaniac (author)  stypayhorlikson027 months ago

to learn robotics in genereal and build your first robot without costing a lot of money.

What is it's purpose? What is the purpose of the beetlebot?

What is it's purpose? What is the purpose of the beetlebot?

tiagolinux8 months ago

Yeah,it's good!

gabriels59 months ago

does it have a off and on switch

robomaniac (author)  gabriels59 months ago

You Simplify remove the batteries.
avenged7x1 year ago
Would it be possible to add an LDR so that the robot can be controlled but when it hits an obstacle(for example a chair) it'll still turn on its own?

wow . zero programming = 100 percent fun

mkovtchega1 year ago

Will these spdt switches work? They are from and old ball mouse.

hkarlis1 year ago

well I have a little problem I am not getting a 3 pole switch ad I am just getting a switch like this (posted). can u tell me if this works, pls give the way of connection diagram or tell how to connect it . And if not suggest me a site where I can find the 3 pole switch(it should deliver in India)

Enkeim hkarlis1 year ago
watch the picture closely again... at the bottom of the switch you can see that there is the 3th pole. So it should work ;)
hkarlis1 year ago
Enkeim hkarlis1 year ago
Yes why not?
robomaniac (author)  hkarlis1 year ago

yes, those are exactly what you need.

good luck

hkarlis1 year ago

is there any other method of making it as i am not geting the right switch

hai its awesome dude. quite impressive with small steps.

Aditya M1 year ago

I also made it but it was little different.........

but the concept pretty matches with this......

I Don't have any picture of that!!!

Tbus1 year ago

This is a great lab experiment. I'm taking a Robotics Fundamentals home study course (http://www.ciebookstore.com/robotics-fundamentals-...) and this instructable covered a lot of what I learned in my class. Thank you!

mfernando31 year ago
AWESOME STUFF man. Just wanted to give you a quick praise. Thanks!
hussein13 years ago
hey man can i use an mouse spdt switch?? please reply on this site please.
1 year old reply -.-'
The mouse SPDT would be hard to use, you have to de-solder, and the switch doesn't have an actuator lever (The metal thingy). But it could work! You could hot glue the paper clip on, that's what i tried to do, It fell off after the bot hit a wall 3x
CarlyAnne73 years ago
Can I Just Buy One From You ?
You can buy one from Solarbotics now!
Solarbotics Beetle Bot
meghams2 years ago
hey very nice bot ..!!wanna try right away ...but one thing which is boggling my mind is how you have fixed those motors in such a inclined angle..??
raghav572 years ago
i am raghav. i am 12 years old. i got all parts and i made some but how to stick SPDT switches and motors to battery holder.and where can i get heat shrink.the only part i didn't get.where can i get please say
rashtekar2 years ago
my bot is not going front when i coneect battries to the motors directly they work properly...but when i connect it to the switch and spdt switches it works slow and doesnt move forward...plz reply....i have to show it on monday..:-(
rashtekar2 years ago
my teacher is asking the uses of this beetle bot...what do i tell her????
TANMAYEE2 years ago
can u please help with the uses of this beetlebot?? do reply soon. Got an urgency. thank you. :)
Wisaam2 years ago
Can you please tell me the actual function of the SPDT switch and how does it work?...Please do reply..
prakash03022 years ago
hi it's cool idea...........!!!!
indradiana2 years ago
can i use two 3 volt motors by only using two 1.5 volt batteries?
does the beetle robot still work normally ?
niljo2 years ago
Hi!! i made the beetle robot, bt it wnt wrk if i let go of the switch.. i have to keep it presd..and the funny thng is tat wen i press the spdt swittch on right side, the left motor rotates and vice versa... cud u pls help me wit dis...
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