Arduino Defusable Bomb Tutorial (Countdown Timer)




Posted in TechnologyArduino

Introduction: Arduino Defusable Bomb Tutorial (Countdown Timer)

Why I made this.

There are other tutorials of making alarm clocks and other defusable bombs, they are really good. but they are to complicated for my needs. This is a simple countdown and booom bomb.

So if you are looking for a simple to build and simple to use defusable bomb then this is for you.

Disclaimer and safety

There is no explosive or other dangerous stuff in this bomb. Only sound and light.

!!?!! Only use as toy. Don´t use to scare people. Don´t try to connect explosive to it, the circuit is only made for fun, and is not stable, or safe to use with explosives so just DON´T do it. Don´t place it in public places, you can get in some seriously trouble with the police !!?!!

Use it for fun, and be carefully.

When you connect a wire from + connector in the box. to the connector from the battery + side ( That is the RED wire) then the bomb is on and show 1111 in display.

There are 3 connectors in the box, 1# = V 2# = Gnd 3# = Fake wires.

when you push start button then its starts to count down (you can change this in the sketch)

When the bomb reach zero . the bomb will show 666 in display, light the led and make a high noise from the buzzer.

To reset, press reset button, and 1111 will show in the display again.

To change wires there are screw connectors in the box. and under the tape near the dynamite.

Simple loose the screws, and change the wires that have been cut over to start a new game.


Two teams: terrorist and counter terrorist

Bomb timer: set to 30 min.

Points: Disarm in 1 try =100p. Disarm in 2 try =75p. Disarm in 3 try =50p. Disarm in 4 try =25p

Disarm in 5 try =10p. Bomb explode counter terrorist -50p / terrorist +100p.¨

One team will start with the bomb.

The other team will try to find and disarm the bomb.

Every time counter terrorist finds the bomb, they will have one single change to cut the wire, that disarms the bomb.

If there are connected 4 fake wires and 1 real. Team counter terrorist have to find the bomb a maximum of 5 times.

If team counter terrorist don't manage to disarm the bomb. they lost the round.

Every time the bomb disarm or explode, teams switches sides.

Have fun.

Step 1: Things You Need

You can make this project for about 7 dollars. if you use scrap and things you have in your house. I buy almost all my stuff on Cheap prices and free shipping.


  • Arduino uno, nano, pro, clone ect. (I used Nano)
  • 4 digit 7 segment display i use tm1637 (If you are using another display maybe you have to make some changes in the sketch)
  • Breadboard for testing
  • Piezo / Buzzer
  • Red Led
  • 100 Ohm resistor for buzzer ( Please check for size for your self)
  • 220 Ohm resistor for led ( Please check for size for your self. (But somewere between 200-300ohm schould work)
  • 10k Resistor for button ( Please check for size for your self)
  • Power supply for Arduino (I used 4 X AAA)
  • Jumper wires / Dupont wires
  • 2 Momentary button


  • Saw
  • Wire cutter
  • Scissor
  • Hobby knife
  • Screwdriver
  • Solder iron
  • Glue gun / Or hobby glue

Random stuff:

  • Round iron bars (Wood is better. my bomb is very heavy)
  • Box(I used cigarette pack, plastic is better, don´t start smoking just to get one;))
  • Tape
  • Wire connectors
  • Wires (to connections, battery, fake wires)
  • Thin round iron, pencil or other thin round thing. (to make curling wires)not needed


  • Arduino programmer
  • Library for the tm1637 display

Step 2: Make the Dynamite

First cut your tube in 6 pieces. (the length depends on the diameter of your stick)

Prepare the coffee filters, by cutting them open, and clean the sides.

Next roles up the dynamite. The endings should have a little extra, so you have something to stuff inside.

Take some FAKE WIRE. And put into the end of the sticks.

Stick the rest of the coffee filter in and done.

Step 3: Make Battery

Connect + to -. Be sure not to short cut anything. its a serial connection of the batterys that we are making.

if any doubt, search serial connection to be sure.

I used the connections from a old battery holder.

Tape together and put them in to the dynamite tubes.

Step 4: Test Circuit on Breadboard

Connect every thing as you see in the picture.

The reset button is not in the sketch. that is because we use the reset pins on the arduino.

We could make it in the sketch. but i think this is a fast and easy way to reset the bomb.

Arduino pins:

Pin 13 - Led

Pin 6 - Buzzer

Pin 4 - Countdown button

Pin 3 - Clk (display)

Pin 2 - Dio (display)

Rst - Reset button (Use the reset pin, on my nano clones they are named RST. On a arduino uno i have it says RES)

Step 5: Upload Sketch to Arduino

You have to download library for the display.

From GitHub avishorp has made a nice one.

I have made some comments on all most every line in the sketch, so hopefully it is a little easier

for first timers to understand the sketch.

The sketch is also as download in the bottom.

Step 6: Make the Control Box

Cut holes for display, buzzer, wires and the led. and for buttons.

Step 7: Putting Things Together

Glue the sticks together. Put tape in both ends. Wire it all up

I hide gnd inside the box. so only fake wires and + is going out under the bomb.

Use the same diagram as on the breadboard. solder it all together and assemble the bomb.

Power it up.

Step 8: Now Your Done. What Could Be Better

Congratulation you have finish the tutorial.

Some thing that could be better. Use plastic box it looks better and is stronger.

Hide all other wires inside the box, so only fake wires and + wire is visible. I made all my wires visible for the looks.

Make a rain proof design to use in all weather conditions.

Change the sketch so that you can change the time by button push. on this vision you have to change it in the sketch.

Please let me know if you find any problems with the sketch or in the circuit. So that i can change it, i´m only human so mistakes can be there, but i have tested it and it should all work fine.

Use wisely

Please don´t scare people with this. Put it in a bag under transportation.

!!Don´t try to connect any explosive to it. it´s not made for such things. and is differently not safe!!

Now go outside and play:-)

Step 9: Download Sketch

Download the sketch and upload it to arduino

3 People Made This Project!


  • Space Challenge

    Space Challenge
  • Science of Cooking

    Science of Cooking
  • Spotless Contest

    Spotless Contest

We have a be nice policy.
Please be positive and constructive.




still love this one


the start button is not working, and the reset is only when i power it up ,it counts down 15 sec to 0 and then booooom.then you see 666 and after a few secconds it again counts down from 15 to 0 over and over,and i can not use start button,pfff

what did i do wrong now haha

so it resets continu on the display ,no 1111 in the sceen

but reset works ok.what can i do ?

i got is almost 100% working now,i refer a couple of times to my well placed name WANNADUino, the wannabe arduino tech, not

the board i was using was a 168 atmel not a 328atmel, that was 1 problem and the rest was mabey a misplaced file,i cant see it for sure,

i did a lot of things after al your help here,also a few pointers i find on the arduino forums, the message i had got about the name type! can also be that the new poster of the librairy puts his name after the item librairy, such as MASTER like this

(LM123-Master) but somtimes that makes also the same problem so it shut be (LM123 ) without the master. and the last thing if this happens ! the ccp file and H file. must be placed a directory highter or in the same directory as the prog file with the same name. first of al...ALL THE CREDITS TO DanishElectronic: MY man, 1 more thing i need help with bro

this is the message. i am getting frustrated, what is this, pls help i now it shitty but i am almost there,i used the same arduino 1.6.8.

used in my eyes the correct folders, and used your sketch and the github link.

and i cant get it to workor even compiled on the board, remember my name eeh haha

1 reply

There is two different folders for libraries.
#1 number 1 folder is where arduino program is. That's the one you taken a picture of. C - programFiles - Arduino - libraries. Don't put them here.! If you have the library in here delete it.

#2 number 2 folder is placed in documents - Arduino - libraries.
This is the correct folder.

Hope it makes sense

Arduino: 1.6.8 (Windows 10), Board:"Arduino Nano, ATmega328"

Build-opties gewijzigd, alles wordt opnieuw gebuild

softgun_bomb_english:25: error: 'TM1637Display' does not name a type

TM1637Display display(CLK, DIO); //setup 4-Digit Display


C:\Users\WANNAD~1\AppData\Local\Temp\arduino_modified_sketch_630080\softgun_bomb_english.ino: In function 'void setup()':

softgun_bomb_english:29: error: 'display' was not declared in this scope

display.setBrightness(0x0a); //control brightness of display


C:\Users\WANNAD~1\AppData\Local\Temp\arduino_modified_sketch_630080\softgun_bomb_english.ino: In function 'void loop()':

softgun_bomb_english:37: error: 'display' was not declared in this scope

display.showNumberDec(numCounter = 1111); //shows 1111 when bomb is connected


exit status 1

'TM1637Display' does not name a type

This report would have more information with

"Show verbose output during compilation"

option enabled in File -> Preferences.

1 reply

All of these errors is because of that display library.

when i delete my library i get the same errors.

Maybe I think you have manually put it in the library folder?

You need to delete the library files you have and start all over.

try follow these steps.

#1 You need to download zipfolder from

by pushing the green "clone or dowload"

then a little pop up window shows up. and then push the download zip.

#2 Then open aduino programmer.

And click on sketch => include library => add .zip library.

find the zip file and push open.

#3 Close the arduino program and open it again (restart) and it should work.

My libraries i had installed, is placed in


Skærmbillede (23).pngSkærmbillede (24).pngSkærmbillede (25).pngSkærmbillede (26).png

Man, Nice project... I have a lcd display 16x2, as I apply to this project?

1 reply

and get also an error reading, in the sketch,about including tm display?

i used robotdyn arduino uno

and want it also on a pro mini and a nanov3

so if yoiu can give exact pins and collors and if all black are 1 at the end same as yellow i think?

1 reply

Have you downloaded the library for the display and installed it?
Do you have the same display?
If you look in the schematic you can see the colors. yellow and black are not the same.
Black is only gnd wires.
Yellow is only used from dio, and from reset pin.
Please look at the schematic. I have deleted the other photo.

pleace exact pin out on nano v3 and pro mini

I don't understand it .pleace a picture also in hd these are a bit blurry

I try to make it now but am stoped

1 reply

Hi it is all in step 4?

Pin 13 - led
Pin 6 - buzzer
Pin 4 - count down button
Pin 3 - clk on display
Pin 2 - dio on display
Reset pin - reset button

Same ports are used on uno, nano and mini. Don't think about it ?

Hope it was helpful