Festive Automation: The Sentient Pumpkin

The Sensitive Jack-o'-Lantern is a clever Halloween-themed project that combines two different types of remote interaction: Motion Triggering and IR Control. Using the Elegoo Super Starter Kit, this project creates a "living" decoration that reacts differently to strangers (via sensor) and its owner (via remote), making it the perfect interactive centerpiece for a haunted porch.

Dual-Interaction Logic

The project's code manages two distinct input streams to control a high-power LED array:

• Ultrasonic Proximity: The HC-SR04 sensor acts as a "Bumper-less" trigger. It constantly pulses high-frequency sound waves. If an object (like a trick-or-treater) enters the 50cm range, the Arduino triggers a "Spooky" color change (e.g., from orange to a flashing red).
• IR Remote Override: Using the IR Receiver Module, the user can cycle through different lighting modes (Static, Pulse, Disco) or adjust the detection sensitivity from a distance without opening the pumpkin. This is handled using the IRremote.h library, which decodes unique HEX codes from the Elegoo remote.

Hardware Driven via Transistors

Because the "Sentient Pumpkin" uses multiple LEDs to illuminate the large interior of the craft, the Arduino's digital pins would be overloaded by the current demand.

1. NPN Transistors: The project uses three general-purpose NPN transistors as "Electronic Switches." The Arduino sends a low-power signal to the transistor's "Base," allowing a higher-current battery supply to flow through the LEDs.
2. LED Matrix: Fifteen 221-ohm resistors are used in parallel to build a bright lighting plate, ensuring consistent brightness across the lantern's face without burning out any individual diode.
3. Circuit Concealment: The wiring is split across two layers of cardboard. The base holds the heavy components (battery/Arduino), while a vertical "Pedestal" holds the LED matrix directly behind the pumpkin's eyes, hiding the "Guts" of the machine from the viewer.

Creating High-Impact Festive Art

Instead of a real pumpkin that rots, this project uses a printed photo on cardstock supported by a hidden cardboard frame. This makes the project reusable year after year. The effect is a professional-grade animatronic experience that proves you don't need expensive equipment to build high-quality, interactive festive art.

Halloween is near so I have wanted to use my new Elegoo Super starter Kit to do a Sensitive Jack-o'-Lantern.

I'm thinking about a lantern which change its color when someone passes in front of it, but I want also to control the light and the sensor.

Now we see how to do that.

HARDWARE:

In this case the circuit is quite easy, there are an ultrasonic sensor, an IR Receiver Module, some LEDs and transistors.

For the first time, thanks to Elegoo, I can use an IR Remote Control, so with this I can control the lantern.

This is the circuit diagram:

STRUCTURE:

I haven't wanted to use a real pumpkin but I have wanted to build it by myself.

I need two things:

• A photo of a jack-o'-lantern

• A sheet

In this way I can print the photo on the sheet and with a pedestal I can substain the jack-o'-lantern and all circuits.

I created this structure with some cardboard which will sustain the lantern, in this way I can also hide the ultrasonic sensor.

All circuits stand in this structure.

You can do it with other materials such wood or plastic.

I put the circuits on the bottom and all LEDs on the vertical layer, in this way the jack-o'-lantern's photo covers the LEDs but the final effect is a light inside the our "pumpkin."

Finally, this is my project I know it can have some defects but for me the idea is good and it is easy and rapid to do.