Instructables
I made the scariest pumpkin ever! Nothing gory or disgusting, just something that will scare the kiddies and hopefully score me some candy. How? Well, I am glad you asked. I rummaged through my parts bins and came up with an idea. What if I connected a horn to an Arduino and let out a nice blast when someone came around trick-or-treating. Hopefully they are so scared they drop their bag-o-candy and run away, leaving me with plenty of treats.

Note: The key to this project is the delay. You could just wire the horn to the button and I am sure you would get a lot of people to jump. Add a delay to the horn and when they turn their back, the real fun begins! Honk!

You can find this build on the MAKE blog, along with other really cool Halloween projects and contests.


 
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Step 1: What you need

Picture of What you need
Parts Needed:
  • Aduino
  • ProtoShield
  • Servo
  • Wire
  • Pumpkin - Real, plastic or foam
  • 12Volt battery
  • Car horn - $7 at local car shop or junkyard
  • Buttons and/or switches
  • LEDs - Any color, but I like orange
  • Heat shrink tubing

Tools you need:
  • Soldering Iron
  • Pliers
  • Pumpkin cutting/carving supplies
  • Glue gun

Step 2: Cut/Carve up the pumpkin

Picture of Cut/Carve up the pumpkin
IMG_5078.JPG.jpeg
The foam pumpkins are really easy to carve. It looks like a classic, smiling, jack-o-lantern. The kids will never suspect anything.

You can use a real pumpkin, but I picked this one up for $5 at a local craft store. Using a real one is fine, but photographing it over a few days can get messy so I decided to use a foam version.

Step 3: Selecting a nose button

Picture of Selecting a nose button
I had an arcade game button lying around, so I used it for the nose. Also, I had an old doorbell button I used to trigger the horn. You can use almost any button that you have in your scrap bin. 
bsnob3 years ago
if your are going to go through the trouble of using a servo ,then why not make it similar to the silly string shooting aduino pumpkin, only instead of having the servo hit a button or a can of silly string , use an airhorn, ive even seen them at the dollar stores now, a little cheaper i think and it may be louder too
Screamo4 years ago
Did u get any candys?
cdousley4 years ago
if the arduino isnt hooked directly to the horn wouldent a relay be easier than a servo and a button?
thats exactly what i was thinking
I guess if your a good programmer and dont feel like buying a relay
miniclipper4 years ago
I wet my pants looking at this
mattccc4 years ago
looks like this can also be done with the basic stamp too
nitrox0274 years ago
in your diagram you have 2 left eye leds and no right eye
and you could have just used a relay instead of a servo and a button, but i guess you just used what you had
wurx (author)  nitrox0274 years ago
 Exactly! And I thought it was a bit amusing to use a servo to press an old doorbell button!
nitrox027 wurx4 years ago
lol yah, i actually like that idea though lol
p.s. i watch all your videos on youtube for the maker shed lol
wurx (author)  nitrox0274 years ago
 Haha! Actually the pumpkin has 2 left eyes, makes him extra spooky. OK, not really....I'll have to fix that. Thanks!
WyoJustin5 years ago
That's funny, I love that!  Next project, here we come.

wurx (author)  WyoJustin5 years ago
 Thanks! If you make one, please send me some pictures. I would love to check it out.
WyoJustin wurx5 years ago
We posted our Jack-o-duino at http://wyoinnovation.blogspot.com.

Justin and Elizabeth
WyoJustin5 years ago
Don't forget to mention the servo in your parts list.
wurx (author)  WyoJustin5 years ago
 Oooops! Thanks! Adding it right now.
this seems like alot of work to make a pumpkin honk... Couldn't you just wire and old 1157 bulb to a 12 volt source on the dim side, Then the bright side and the horn to a switch. Then you get an instant burst of bright light and a honk... Great build though. maybe I am missing the point or something... thanks for posting!
The key is the delay!  The delay is the most important part!

When you push the button you EXPECT something scary to happen.   The horn can't go off until you're sure that the button doesn't do anything scary.

-Andy
wurx (author)  VRAndy5 years ago
 Exactly!
nolte9195 years ago
I have two questions.  I have to admit that although I program microprocessors in C for a living I've never used an arduino.  I don't see a function "main" in your code or any function that calls the routines setup() and loop().  It seems you'd need something like:
main(){
   setup();
   while(1){
      loop();
   }
}

Also, is there a chance you could press the button so fast that the code doesn't realize it was pressed.  In other words the button was pressed and released while the treat() function was running?  Or in practice is that not a problem?
wurx (author)  nolte9195 years ago
You do not need a "main ()" function when using the Arduino IDE.

You do need a "void setup()" which is run 1 time at startup. Also, you need a "void loop()" which is run over and over after setup. That's the basics, there is a lot more, but it's all really easy.

I made an intro to Arduino video here. And another one, and another, and another, and more ! :)

As far as pressing the button and it not registering because of the program running a function. Yeah, I it can happen, but it was not an issue. It's a honkin' pumpkin, not an autopilot! Haha!
buttersnake5 years ago
Its perfect, simple and I can see it would be very effective seeing how it delays a bit. +1
wurx (author)  buttersnake5 years ago
 Thanks! I did test it, and it worked....and worked well! :)
comodore5 years ago
Hahaha!
That is so simple, yet very very cool!
I really like your project!
And yea, I got a bit shaked when I was watching the video for the first time!  xD
I might make one for my self!
Thanks!
rate: *****
wurx (author)  comodore5 years ago
 Thanks! If you make one, please take some pictures and send them my way!
comodore wurx5 years ago
Will do!  :)
Why don't you use a solid state relay to trigger the horn instead of a servo?  It seems a lot simpler and a bit cheaper (unless you already have a servo).  I like the idea of the project though :D
wurx (author)  Radioactive_Legos5 years ago
I made it with "stuff" I had laying around. The best route would be to use a 555 (or 556 for the LEDs)  for the delay and a relay for the horn. I had an Arduino, and I thought it was kind of funny to press a doorbell with a servo. Yes, your method would be a lot cheaper. Thanks for the feedback!

Salsa7665 years ago
 u could also probably enter this is the ardunio contest 
wurx (author)  Salsa7665 years ago
 Haha! Thanks....I did! :)
knexfan91825 years ago
Nice but i would try to hide the LEDS a little bit more.
wurx (author)  knexfan91825 years ago
 I thought about that. Maybe adding some vellum in the eyes. However, the LEDs actually look like the pupils of the eyes at night. Personal preference I guess. Thanks for the feedback!