Bomb Defusal Program That Actually Fires


I'm pretty much a novice with arduino, I've only done basic programs with my Arduino UNO kit, but I'm willing to learn and put some serious hours into what I want to achieve.


I work at an airsoft site and I want to create an interactive prop for a MilSim event we run. I am the resident pyrotechnician and have remote firers and an assortment of pyro articles but I'm wanting to go one step further.

I want to create a device where teams have to actually defuse a bomb. If successful, the device will shut down. If they do it wrong, or if the timer runs out, it will trigger small charge a safe distance away. The charges I would use are fired by using an ematch, which requires a minimum of 750milliamps to fire. I'd probably use a two or three at 2 second intervals to simulate a building self destruct.

I'd like to have a couple of ways to defuse it. 1) A 4 digit code that teams would have to find. 2) A key switch that would simply prevent any power going to the ematches.

I'd ideally like the teams to have three attempts at entering the correct code. If all three attempts are wrong, the device would reset the countdown to 30 seconds, at which point teams would have to evacuate the area.

I'd also like this 30 second timer to be triggered if teams attempt to defuse it manually by cutting wires - like old fashioned bomb defusal shown in the movies.

I have access to a 3D printer so I'd be able to design a pretty good wall panel that would act as the self-destruct control panel.

Thoughts? Is it possible, or am I being a bit too ambitious with what I want to achieve?


I solemnly swear I have no nefarious intentions!


I solemnly swear I have no nefarious intentions!

That might be true, but what is to stop someone with nefarious intentions reading this and doing harm?

That might be true, but what is to stop someone with nefarious intentions reading this and doing harm?

It'd be a pretty elaborate way to do harm! I'm not asking for instructions, just an assessment on how feasible it is.

Since you are a novice, DEFINITELY test this with the charges before the event! As far as I know, this is feasible. Relays connected to the power source for the detonators, a keypad program (if you use the keypad idea), and a timer system that could use an LCD or maybe just a little bar graph made of LEDs. Sounds fun, incredibly dangerous, but fun!

The code will be the same, regardless of whether a LED or match is lighted on a failure.
No code problem so far, and the matches are secured with their ignition voltage cut off.

All is totally feasible from the Arduino pov. Safety of course is your responsibility. What I do want to add: the fireworks at “a safe distance from the trigger” is not enough by itself, as you don’t know where the other people are when it goes off!

Keypad entry: lots of examples you will be able to find with a simple Google search, including timeouts and limits on tries. A very common application for things like door locks.

Countdown timer & display: again you’ll be able to find lots of examples for this.

A key to physically disable the thing: likewise very doable.

The hardest part could be the detection of wires being cut. Especially if it’s the team cutting the actual wire to the fuse: you will be able to detect this easily (run a small current, 0.1 mA is enough to detect a closed circuit but not to set off your charges), but after that the wires are cut so you can’t set off the fuse any more.

A possible way to circumvent this: the wires are fake and the real link is wireless (use a second Arduino with receiver at the fuse). Much harder to disable. Have the fuse arm when no message is received for say 1 second. Send “disarm” messages every 0.1 seconds. Then it will blow even if the main device is given the sledge hammer treatment. Add a “total disarm” option so you can instruct the fuse side to really shut down.

The hardest part could be the detection of wires being cut. Especially if it's the team cutting the actual wire to the fuse

Maybe not! you can have the relays for the igniters powered all the time to open the circuit!
If the relays are next to the explosives (I.E. somewhere the players can't go), you can have the wires to power those going from the arduino. Get some relays with 2 poles (one switch is connected and one isn't when powered) and if someone cuts the wires or if the arduino stops powering the relays, everything goes boom!

I have made an image, since this is hard to explain.

Tamper-proof Bomb.png

I so want to build an Airsoft disrupter...

Are they supposed to cut a wire? Then give em wires to cut and put them on pins with button software.

I used to be familiar with things that went bang/boom. Not sure how I survived with both eyes and all my digits.

You wouldn't be able to use smoke devices to simulate bombs? That could go much closer to your customers.

One way to make very impressive BOOMS is to fold up big paper triangles (fold like a flag) with not a lot of powder and a fuse and tape them with a couple of layers of fiber tape. It ends up being flat but when the powder ignites it forms a ball with no heavy pieces for shrapnel. You can make a few with the powder it takes to make an M80, you won't get the hurt-your-ears sharp bang but you get a lot of mainly harmless boom.

Most important question I have is how are you with code?