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Table of contents
Abstract
A motion-triggered haunted box that reacts with fog, eerie whispers, servo-driven lid shakes, and terrifying light effects. It brings Halloween fear to life through electronics and immersive storytelling.
Project
The Story of The Vessel
In the dim glow of my workshop, The Vessel came to life — a haunted artifact sealed within a brown box. Its purpose: to blur the line between technology and terror. When someone gets too close, the box awakens. Fog spills from hidden vents, ghostly whispers echo, the lid starts trembling violently as if something inside is trying to claw its way out, and the screen flashes warnings like “CONTAINMENT BREACH” and “DO NOT OPEN.”
This project was born out of my love for Halloween and interactive electronics. I wanted to build something that didn’t just look spooky, but reacted to its environment — something that feels alive. The Vessel does exactly that, combining sound, light, motion, and fog into one cohesive horror experience.
️ Hardware & Design Overview
At its core, the system is powered by an ESP32-S3 microcontroller, which orchestrates the fog generation, servo motion, audio playback, display animations, and lighting effects. A 3.2-inch ILI9341 TFT display serves as the communication interface of the “entity,” showing ominous warnings like “MOVEMENT DETECTED” and “DO NOT OPEN.”
An ultrasonic sensor (HC-SR04) continuously scans for motion. When someone approaches within 30 cm, it triggers the full sequence — fog, sound, vibration, and visual effects — creating an immersive scare.
Fog & Power System
The fog effect is produced by a D20mm 108kHz ultrasonic mist maker atomizing fogger module, powered independently by a 3.7V Li-ion cell for stability. This small humidifier generates dense, cold vapor that escapes through the vent openings modeled into the box’s design.
The fogger’s power line is connected through a 2N2222 NPN transistor, allowing the ESP32 to switch it on or off electronically during each stage of the animation. A toggle switch on the exterior serves as the main power control for the entire system.
Separate power rails ensure smooth operation:
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3.3V → ESP32-S3 and TFT display
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5V → Servo, RGB LED, and MP3 module
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3.7V (direct battery) → Fog generator
All grounds are tied together for common reference, ensuring stable performance without interference.
Servo “Hand” Mechanism
Instead of a simple lid hinge, I designed the servo motion to feel alive. The servo arm is fitted with a metal pin, acting like a skeletal hand that pushes against the lid from underneath. When the servo thrashes, it mimics a creature trying to escape — tapping, shaking, and pushing the lid in quick bursts.
This small mechanical detail gives The Vessel a chilling realism, especially when combined with the synchronized sound and fog bursts. During the “DO NOT OPEN” sequence, the servo rapidly shakes in short, violent pulses to make it appear as though something is struggling to break free.
Audio & Lighting Effects
All sound effects were obtained from Pixabay and are royalty-free. Each track corresponds to a stage in the sequence:
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Ambient hum for idle mode
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Whispering voice for detection
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Glitch and static during containment breach
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Screams and slams during the escape attempt
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Fading energy tone when containment is restored
Audio playback is handled by a YX5300 (YS-M3 v6.03) MP3 module, which reads from an SD card and plays individual tracks triggered by the ESP32’s GPIO pins.
A common-cathode RGB LED glows and flashes in sync with the sound and servo motion. Subtle red fades, white flashes, and orange flickers simulate panic and warning lights.
CAD Design & 3D Printing
The enclosure was fully designed in Autodesk Fusion 360. I modeled vent openings and fog channels to direct mist outward in a cinematic way. The servo, display, and ultrasonic sensor were all given precise mounting slots. The design was printed on a Bambu Lab A1 Mini, using a dark brown filament for an aged, wooden look.
Circuit Integration
(Insert wiring photo or diagram here)
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ESP32-S3 handles all sensor inputs and outputs.
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Servo connected to GPIO 15.
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Fog control transistor on GPIO 6.
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TFT uses SPI interface (CS 7, DC 16, RST 18).
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RGB LED on pins 8–10.
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MP3 module uses trigger pins 1–21.
All components share a common ground, with power supplied by two separate buck converters from a shared 7.4V Li-ion battery pack.
Software & Timing
The firmware was developed in Arduino IDE and follows a timed state machine:
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Dormant Mode: Red LED fades softly, TFT shows “Dormant…”
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Detection: Ultrasonic detects movement, TFT flashes “MOVEMENT DETECTED,” whisper plays
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Awakening: Fog starts, LEDs flicker, static sound plays
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Possession: Servo shakes violently using the metal “hand,” scream plays
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Containment Restored: Fog stops, lights fade to blue, and display returns to “Dormant…”
Each stage has carefully timed durations for cinematic pacing and reliable reset after the full sequence.
Demonstration
When powered on, The Vessel waits silently in its dormant state. As soon as someone comes near, fog slowly rises and whispering begins. The lid twitches, then violently shakes as screams echo from within. The vents blast mist while warning messages flash on the display — and just when it feels like it might burst open, it suddenly stops.
The fog fades, the lights dim, and the display calmly shows “Dormant…” once again — ready for the next victim.
YouTube link: https://youtu.be/QOi8eOr0J-8
️ Conclusion
The Vessel is more than a prop — it’s a living piece of horror art built from electronics and imagination. Every motion, light, and sound is coordinated to tell a story. The addition of the servo “hand” mechanism and the ultrasonic fogger takes it beyond a simple gadget into a full Halloween experience.
It’s proof that even with compact components and maker tools, you can bring fear to life — one circuit at a time.
Attachments
final_modified_body.stl
top_final_modified.stl
References
References & Credits
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Pixabay Royalty-Free Sound Library – source of all audio effects used
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YX5300 / YS-M3 MP3 Player Module Datasheet
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Bambu Lab A1 Mini 3D Printer – used for 3D printing the enclosure