Go Down

Topic: Live Action Scenario Bomb Prop (Read 8607 times) previous topic - next topic


Apr 20, 2011, 10:28 pm Last Edit: Apr 20, 2011, 11:44 pm by dead-techie Reason: 1
I'm sure if you guys have been on this site a while you have seen threads about bomb props for live action scenario games (paintball, airsoft, reenactments ect.)
Okay not only am I new to the entire world/idea of Arduino but I don't even know where to start and barely understand what it is.
I will be making a prop bomb and for my purposes it will be used in a live action paintball version of the popular Call of Duty game type Search and Destroy (this page explains the game type once you look past all the video game stuff http://callofduty.wikia.com/wiki/Search_and_Destroy)
So I would like to keep things similar;
5-second arm time for bomb
45-second fuse
5.1 defuse time

Now I know there are a couple of other threads that exist talking about this but I would like to start a new thread for this for a couple reasons;
- I pretty much need to get someone to explain how to do this as if they where explaining it to a child, I know quite a bit about tech (I can rebuild an Xbox or PC just fine) but this is entirely new to me and have no experience with programing at all
- also ultimately I would like to create a step by step guide to doing this because I know that there are a ton of people out there that would like to build one, but have no resources to do so


this is one of the best designs I have seen

I know this kid used an Arduino type board

and this guy used no board witch to me is a great idea

my main requirements would have to be something like;
-a two key power switch (one key + and one key -)
-a ten key style keypad to arm/disarm
-a LCD display for code entry
-a large count down clock (like an eight number clock displaying minutes, seconds, milliseconds and centiseconds)
-a siren/alarm to simulate detonation (currently looking into industrial fire alarms w/ strobes)
-long lasting battery/rechargeable battery (might be camping during use)
-maybe a tether option?
-of course if you have any other ideas to make this awesome please let me know,

oh and  I am on a budget so I don't want this to get to pricey,
but am will to hear all options
any help is much appreciated


Apr 20, 2011, 10:41 pm Last Edit: Apr 21, 2011, 04:58 am by retrolefty Reason: 1
Can't you just be happy with a blinking LED like the rest of us?  :D

By the way if you build one, don't take it to an airport.



Can't you just be happy with a blinking LED like the reset of us?  :D

By the way if you build one, don't take it to an airport.


blinking LED, lol
where is the fun in that??


You can display several large digits on the commonly available 16x2 or 20x4 LCD displays.  Your timer can switch from HH:MM:SS to MM:SS.SS to SS.SSSS as the time gets close.  The LCD control chip might also include connections for a 4x4 keypad.  Those 16 button inputs can be used for your numeric keypad and various arming/disarming switches.
Send Bitcoin tips to: 1G2qoGwMRXx8az71DVP1E81jShxtbSh5Hp


And what happens when some player comes along with his watersoft bomb disrupter?
"Pete, it's a fool looks for logic in the chambers of the human heart." Ulysses Everett McGill.
Do not send technical questions via personal messaging - they will be ignored.
I speak for myself, not Arduino.


okay so from my personal research I have figured out that I should use a Duemilanove as my base and I have found most of the components that I will be needing but I was curious if anyone knew if I could use a Hirsch ScramblePad in conjuntion with Arduino?
its this thingy:

and here is a video that shows the pad in use integrated into one of their stations:


I dont necessarily need this key entry I just really like how it scramble the numbers and if I can make it work I will


That keypad will not work for you unless you can figure out how to power it.   While its external power port for readers is 5v, the device itself runs at 24v and appears to draw as much as 600mA, which is pretty hefty.  You'd need a large, heavy battery to keep it lit and running for very long.  That said, it's also not documented how to run it with an Arduino, which can make it really hard for a novice.

Your biggest issue here, as a novice, is going to be managing how many pins you'll need in order to make this all happen.  Using an UNO, you're very limited on the number of I/O pins.  You can cheat and get a MEGA if you want to go cheap on almost everything else below.  Power / battery / driving a large horn+strobe isn't going to be DEAD EASY, but it will be easier than some of this:

1. In order to drive as many digits as you want, you will either need to go with a serial display (two, actually... See below) or use a rather large number of Arduino digital pins to drive the displays.   If you choose to go the cheaper route, you will need to use shift registers which, although not all that hard to use, are not trivial for many novices.
2. Your keypad will likely take up 7 pins on your arduino.   Given that the UNO (the replacement for the Duemilanove you mention) has only 11 dedicated digital pins, assuming you keep the serial and analog pins for serial and analog uses, this will kick your butt a bit.   Again, shift registers can be used, but NOT easily in this case as there is very little out there in the way of documentation for this scenario. http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1258567421 is just about the only example I've seen that is likely to work and involves extra work.
I link to a serial version of the keypad below.  It's worth noting that if you want to use a serial keypad AND the serial displays in #1, you will need to use SPI to communicate with them, or setup SOFT SERIAL (it's a library out there) to use different pins than the dedicated serial pins.
3. MORE PINS! You will need either another 6 pins OR a shift register setup OR (my recommendation) another soft serial connection to drive your LCD.   You can find a nice serial LCD in my links below.   Writing to it is easy as pie and there are tons of tutorials out there. 
You might also try:http://www.adafruit.com/index.php?main_page=product_info&cPath=37&products_id=347  This one is a VFD instead of an LCD, but it's different from the other videos, so that might have a cool factor.  Also: Adafruit products almost universally come with beginner level tutorials that can really help!
4. about that buzzer / alarm?  Your lowest stress bet is going to be a high volume piezoelectric buzzer. I've linked to one below.  You will NOT be able to drive this directly from the Arduino's digital pins.  You will need to switch a transistor or mosfet to drive it from a higher voltage external power source.   Step up converters will likely not be able to provide the current it needs, so having your battery be 10-12v would be helpful.  Just remember you'll THEN need to use a stepdown regulator to drive the Arduino itself.  Another option would be to simply use two batteries.

As an aside, you might also look into using ONE LCD to display everything from countdown to input.  For this, you could use either a straight 16x2 or use one of these:
http://www.sparkfun.com/products/8884 or http://www.adafruit.com/index.php?main_page=product_info&cPath=37&products_id=250
If you use a GRAPHIC LCD like one of these, you would be able to display bitmaps ala team logo or explosions or other fun.

Must get back to my actual job now, but I hope it works out for you! Remember, boys and girls, never use 3.3v devices connected straight to an Arduino's 5v pins.  This doesn't just mean the POWER connection, but also the logic pins.   Unhappiness will ensue.

I'm mostly going with Sparkfun as a supplier simply because their site has just about everything you need.  Searching will likely find cheaper options, though perhaps not as high quality.

Serial numeric LED display that can be placed side to side (to enable as many digits as you specified):

One of the keypads shown in a video you linked to:
(I drew up the datasheet for this one - at least the mechanical datasheet.

Essentially the SAME keypad, but using a serial connection, which would make your life easier - FAR fewer pins used (essentially 1):

Serial LCD (note, this is the 5v version.  do NOT accidentally get a 3.3v version.  It will die horribly before too long):

The alarm buzzer:
A circuit that WILL work for driving THIS buzzer: http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1293472286
If you want max volume, make sure you figure out which power source you're driving it from and use an appropriate resistor to lower the current to the stated maximum 120mA.  You can google "led resistor calculator" to get a bit of free advice on the resistor once you've chosen a battery.


I know this kid used an Arduino type board

Kid? I resent that remark! (I'm 22)

I have the parts list I used, along with the code and schematic up on my site: http://nightscapetech.com/index.php/projects/bomb-prop
My website tanked hard last week (I was messing with bleeding edge packages, big mistake) so a lot of the links aren't working. The Google Code mirror link works, the schematic link works, and the parts list links work.

I used a serial LCD from Sparkfun to get around the problem with limited number of pins.
I use a 12v 20W 115dB siren that I got at a local store. It looks similar to this one:


Kid? I resent that remark! (I'm 22)

Oh, lol sorry dude, I'm 21

Yea I was all over your site before I came to the forums and I must have been there while it was down because there wasn't much to look at.
I might just go with the mega board so I dont have to worry about pins, although it seems like if I keep adding stuff that could be an issue anyway.
and as far as the siren goes I am torn between using something like you used (or what others have suggested) or using my initial idea which was to use an industrial fire alarm much like whats in high schools and public buildings like this: http://cgi.ebay.com/WHEELOCK-MT-24-LSM-MULTI-TONE-FIRE-ALARM-STROBE-/110510935941?pt=BI_Security_Fire_Protection&hash=item19baf70f85
was your finalized version in the one you showed in the 30cal ammo can with the aluminum sheet metal?
because I have debating between using a black pelican style case or a larger ammo can (either a 50 cal or something like this http://store.colemans.com/cart/aviators-kit-boxcontainer-heavy-duty-plastic-p-261.html )

I am trying to go all out for this so if you have any segestions lemmie know.

Quote from: brucethehoon

Must get back to my actual job now, but I hope it works out for you! 

Thank you so much bruce you have given me a great starting place!!


Yeah the ammo can with the aluminum faceplace (that's backed with lexan for strength) is my final version. I used that for cost reasons. I was paying $25 for a waterproof project box vs. $5 for an ammo can and $5 for 10' of aluminum sheet. I also used a 50cal ammo box before. The only thing you need to watch for on surplus ammo cans are dents on the sides and on the latch. If you get the 30 cal ammo can, just note that the keypad fits in there tight (less than 1cm on each side, so you wont have room to fit any mounting brackets in that area). Pelican cases are nice, but expensive.

I used one of those Radioshack Piezo buzzers before I got the siren, and it was still uncomfortable to be in the same room with the prop with just that little buzzer. I just used a simple solid state relay to trip the buzzer (the buzzer is powered by a 12v SLA battery). From what I have read, this is a bad setup, but nothing has burned out or caught on fire yet, so it works for me.

I'd get the sparkfun serial LCD that has been mentioned in this topic already, they are really nice and easy to use.


I was tooling around in Paint.NET and I made a mock up of what I am thinking to do.
I dont know about you guys but it really helps for me to be able to see things on paper.
It looks pretty cool, although the cost is super high right now (around $200).
I am going to try and find ways to cut cost and order a lot of stuff off ebay,
but if anyone has cost cutting suggestions let me know.
lol I can always pawn something.
check it out and tell me what you think;


Apr 22, 2011, 06:14 am Last Edit: Apr 22, 2011, 06:22 am by wizdum Reason: 1
Just 2 things.
Why use two displays (extra unneeded cost)?
You may run into problems with the fire alarm. I have never seen one of those that operated on anything but 110/120v AC

You could also get an accelerometer for around 1/2 the cost of that level switch:


Just 2 things.
Why use two displays (extra unneeded cost)?
You may run into problems with the fire alarm. I have never seen one of those that operated on anything but 110/120v AC

You could also get an accelerometer for around 1/2 the cost of that level switch:

well originally I didn't want to use two displays but I like the look of a six (mm:ss:ss:ss) or eight (mm:ss:ss) digit counter with the numbers ticking by wicked fast, it just seems like a cool effect. the only issue being that I wouldn't be able to see code entry responces in the counter so I need a separate screen for entry purposes... I only put the graphic lcd on there because I thought it would be fun to input bitmap images for detonation, but now that I think of it no one will really notice it if a stobe and siren is going off in their face, maybe your right... if I do go with one screen I could use a http://parts.digikey.com/1/parts/680442-lcd-accy-vfd-filter-20x2-red-vfd-red-202.html top row being the counter bottom being the input registry.

yea I have been running into issues with a fire alarm, but getting the strobe and alarm separate isn't that big of a deal, it just increases cost.
payday is tomorrow for me so then at least I can buy some parts finally.
hopefully I can get everything at once, except the buzzer, strobe and battery so I can actually start the hard part.

and as far as the level switch goes, that was sorta my version of your tether but since the game calls for the bomb to start with the team thats on offense and move around a bunch before getting planted, i figured lugging the tether and bomb around would be too much work. I had sorta already scrapped the level switch when I posted that, it seems like it would be too sensitive, but I will look into the accelerometer as maybe a later addition, seems cool


saw this and thought of you:


saw this and thought of you:

omg thats perfect! totally buying it.

Go Up