Instructables
Picture of The mini pumpkin LED face
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This is a very simple and fun project for kids as well as adults. Using a small pumpkin as a circuit board I created an LED face powered by a 9v battery. This can be a neat little Halloween decoration for work or home. Now, on to the instructable.

 
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Step 1: Materials

Picture of Materials

The main materials for this project is a little pumpkin (bought for about 70cents), a couple resistors and 7 LEDs.

5 LEDs were used for the pumpkin face and 2 for the eyes. Two current limiting resistors will double as eyebrows for the face.

Step 2: Circuit Design

Picture of Circuit Design
The blue and red LEDs are connected in parallel with a resistor to ground as shown in the diagram. Since here we are using one resistor for multiple LEDs in parallel be sure to use one that has the proper power rating.

  • The voltage drop across these blue and red LEDs are 4.5V and 2.2V respectively.
  • The voltage across the resistor with a 9v source and the blue LED in series is 4.5V
  • The voltage across each resistor with a 9v source and the red LED in series is 6.8V
  • The power dissipated by both resistors is ~90mW

Tips

If you are going to try different LED and resistor configurations here are some guidelines.

  • Connecting your resistors in parallel rather than in series is a lot easier since you have to do the soldering inside the pumpkin.
  • If you use blue LEDs you will not be able to hook them in series with a 9v source since there is typically a 4.5v drop across the high intensity type.
  • If you are hooking the LEDs up in parallel like we are here and you use a lower valued resistor (<100ohms) you will probably need one with a higher power rating

Step 3: Cutting open the pumpkin

Picture of Cutting open the pumpkin

Use a knife cut a hole in the bottom, remove the inside pumpkin seeds with a spoon.
Once most of the seeds are removed you can use a paper towel to clean it out.




Ploopy1 year ago
Cool!
I just brought a mini pumpkin and I was wondering what to do with it
and here it is a led pumpkin.
dragonx345 years ago
that is cool
That's very cool! I'm surprised that the pumpkin doesn't short out the components. Someone should sell a kit that has a flexible PCB inside the (fake) pumpkin so you can just snap in the LEDs in the position you want for different faces.
Shifrin6 years ago
Wow, awesome!
Another easier way to figure out what resistors you need, you can go here: http://ledcalc.com/
guyfrom7up7 years ago
nice looking pumpkin there, great idea! Looks like you got all of your tools at the shack. Is your soldering iron the 60 dollar one?
jarv34 (author)  guyfrom7up7 years ago
the soldering iron i had for awhile and i think it originally came from the shack. leds are expensive if you pick them up at radioshack so i suggest buying online somewhere like ebay.
gmoon7 years ago
Congrats--you've gotten "hack-a-dayed"!

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DIY Dave7 years ago
cool