Motion/Wifi Activated Car Horn Pumpkin




Introduction: Motion/Wifi Activated Car Horn Pumpkin

This is a classic trick that all Halloween decorators know and use to frighten Trick or Treaters.

But instead of buying it, why not make your own !?

In this tutorial, I will show you how to make your own motion / Wifi activated pumpkin, from beginning to end. It uses popular, easily available components that you should have lying around.

Let's get started!

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Step 1: Bill of Materials

  1. Bill of Materials

Basic Materials

  1. Pumpkin

Materials for Motion Detecting Pumpkin

  1. Perma-Proto board

  2. Car horn x1

  3. PIR Sensor (Motion Sensor)x1

  4. Female headers x3

  5. Wire (Solid, 24 gauge)

  6. Wire (18 guage, optional

  7. Any Power NPN Transistor or N-channel MOSFET x1

  8. 7805 5V Linear regulator x1

  9. LED x1

  10. 470 ohm resistor x1

  11. 1uf Capacitor (electrolytic) x2

  12. 12v Power Supply (or 12v lead-acid battery) x1

  13. 12v Relay x1

  14. 12v Battery charger x1

Materials for Wifi-Activated Pumpkin

  1. Raspberry Pi (any)
  2. Computer with mouse, keyboard, monitors,ect.
  3. Female headers x2
  4. Wire (24 guage)
  5. Power NPN transistor or N-channel MOSFET x1
  6. 12v Relay x1
  7. Car horn x1
  8. 12v Power supply (or 12v lead-acid battery) x1
  9. micro sd card x1
  10. 7805 5v Linear power supplyx1
  11. 1uf Electrolytic Capacitor x2
  12. Micro usb power cord /A to B USB cable
  13. 12v Battery charger x1


  1. Wood
  2. Wood screws


  1. Solder
  2. Flux

Step 2: Tools


  1. Sharp Blade (or drywall saw)
  2. Soldering iron
  3. Sponge/ cleaning steel wool for Soldering iron tip
  4. Saw
  5. Drill
  6. Drill bits
  7. screwdriver/ screwdriver bits

Step 3: Soldering


When building circuits, I recommend building it on a breadboard and testing it for usability, and then soldering it.

If you don't know how to solder, not to worry. I have posted an excellent video tutorial from Collin's Lab (Adafruit). Acess the link below.

Collin's lab-How to solder

Step 4: Wifi-Activated Pumpkin

Wifi- Activated Pumpkin

To make this Wifi-Activated Pumpkin, I will be using the Raspberry Pi and the Blynk application.

To first write the software onto the micro sd card, consult this link. Writing Rasbian onto a sd card

To set up your Raspberry Pi: How to setup Raspberry Pi

Blynk with the Raspberry PiBlynk with the Raspberry Pi

Once you have setup the Blynk application on both your phone and your Raspberry Pi,set it as your model of Raspberry Pi. Create a new project and a new button. Set the button to GPIO pin 18. Attach the pin to your MOSFET or NPN power transistor, as shown in the schematic on the next step.

Step 5: Wifi-Activated Pumpkin Cont'd

The circuit for the Wifi-activated Pumpkin:

Also build or add a 5v Power supply for the Raspberry Pi.

To build a power supply from scratch, first connect the 12v battery's positive (red) and negative (black) terminals to the VIN and ground of the LM7805. Then connect both the LM7805's VIN and VOUT pins to ground of the LM7805 using the 1ufelectrolytic (polarity sensitive) capacitors.

After that is complete, cut off the USB A end of the A to B USB cable (micro USB cable) and strip red and black (positive and negative) wires. If there are other differently colored wires, just leave them.

Connect the black and red wires to the VIN and ground of the LM7805.

You're Done!

In the case that you are adding a premade supply, make sure that it can supply at least 700 milliamps.

Step 6: Motion-Activated Pumpkin

Build The circuit

The schematic may seem daunting at first, but it is really a very simple circuit.

I recommend building it on a breadboard and testing it for usability, and then soldering it.

Step 7: The Enclosure for the Motion or Wifi-activated Pumpkin

For the enclosure of the wifi activated pumpkin, I cut some scrap plywood into 15x20 rectangles and drilled holes into the sides of two of the pieces of plywood. I then used this as a template, and drilled into the sides of the other two pieces. Then cut another two pieces of plywood for the bottom, and use the same technique to drill holes into the vertical pieces. Now screw the wood screws into their corresponding holes.

You should have a neat wooden box.

Step 8: Pumpkin Carving

Carving your Pumpkin

Last, but not least, we are carving the pumpkin that will be the enclosure for our Wifi or motion-activated pumpkin. Make sure that your pumpkin can comfortably contain the 20x30cm enclosure for the electronics.

I recommend using a stencil which is taped onto the pumpkin, which is then cut out with a knife or a drywall saw, if you have one.

With that, my project is done!

Make sure to vote for me in the instructables contests!

Halloween Decor Contest 2016

Participated in the
Halloween Decor Contest 2016

Circuits Contest 2016

Participated in the
Circuits Contest 2016

Pumpkin Carving Contest 2016

Participated in the
Pumpkin Carving Contest 2016

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    3 Discussions


    3 years ago

    Basicstamp10 is my best friend he also made this

    :) good job

    DIY Hacks and How Tos

    Oh my. This would be such a fun prank. Just put this next to the bowl of candy and anytime you see someone try to take more than one, blare the horn.