Party Pooper

This little house model is made to give you FOMO. When you're away and unaware, its tiny occupants come to life to party hard. They spin and dance around the room to flashing lights and blaring music. However, any noise complaints you will want to make will be in vain. When opened up, the party is interrupted and everyone freezes in place, appearing as regular stationary figures. This is a party you are not invited to, and will never see.

Index

1. Initial Design Concepts (Step 1)
2. Assembly Process (Step 2 - 6)
3. Arduino Circuit (Step 7)
4. Code (Step 8)
5. Conclusion (Step 9)

In case if you want to recreate the Party Pooper for yourself, here is what you will need! As well as a visual representation guide is provided above for easier identification of each component.

Components:

1. Arduino Uno x1
2. Tilt Sensor x1
3. High Torque DC Motor x1
4. 2.1mm Barrel Plug to USB x1
5. 9V 1.2A Power Supply x1
6. Breadboard x1
7. Power Supply Module x1
8. LEDs x4
9. 220 Ohm Resistor x4
10. Herringbone Gears x9 (Planetary Gearset)
11. Spur Gears x2 (Overdrive Gears)
12. 5x3mm Neodymium Magnets x9
13. Wires

Materials:

1. ⅛” Plexi-Glass (Laser Bed Size 18" x 32") x1
2. Plywood (Laser Bed Size 18" x 32") x1
3. WeldBond Glue
4. Superglue
5. Sticky Tack
6. Tape

Equipment:

1. Computer
2. 3D Printer
3. Laser Cutter
4. Soldering Kit

Software Programs:

1. Arduino IDE
2. TinkerCad

In the beginning, our team conceived the idea of a responsive music box. The initial design used sound as an input, with a microphone as the receiver. However, due to technical issues with the microphone component, we switched to a tilt sensor instead. This allowed the device to respond to different angles based on user input. The project's name was inspired by the unpredictable behavior of its components during testing—as if it had a mind of its own, acting erratically and defying expectations. Ultimately, the final design ensures that the model only stops when the user lifts the roof to take a closer look.

Use either WeldBond or Superglue to secure the pre-laser-cut plywood base. Next, insert the ledge supports at two levels as shown in the diagram. Ensure that one side remains open to allow for circuit installation.

Next, use cut pieces of plexiglass are glued to the inside of the walls, covering all the windows. Translucent materials are used to cover the windows, leaving a small slit open to create blinds. Finally, two hinges are attached to the outside of the walls, spaced far apart. Both hinges are screwed in from the outside to the inside.

Stack the 3D-printed planetary gearset (assembled per the first image and diagrams) onto the overdrive gear set. Attach the motor and test its operation, ensuring the tilt sensor functions correctly and verifying that the clear plexiglass spur gears remain planar. Refer to the 'Gear Assembly' diagram for guidance.

Use hot glue (recommended for its forgiving nature when correcting mistakes) or any strong adhesive to secure the 5x3mm neodymium magnets onto the planetary gearset, with their faces facing upward. Refer to the 'Rotation Plan' diagram from the previous step for precise magnet placement.

Next, position the 3D-printed figures—each with a magnet attached to its base—onto the plywood separating layer. Each figure should snap into place, aligning with the corresponding magnets below.

Now, you're ready to attach the display wall, which has the LEDs and buzzer inserted (shown in the image as the wall with many holes). Simply enclose the final wall, sealing all the circuits inside, and you're done!

Here is an Arduino circuit diagram for referrence.

#include <Wire.h> // Wire library - used for I2C communication

const int TILT_PIN = 2;

const int SENSOR_PIN = A0;

const int BUZZER_PIN = 2;

unsigned long previousMillis = 0;

int noteIndex = 0;

bool isPlaying = false;

int tiltState;

int step;

int sensorValue;

int LED1 = 10;

int LED2 = 11;

int LED3 = 12;

int LED4 = 13;

bool muted = false;

int tick = 0;

//init. a 2d array to store notes - this will lengthen depending on how many notes there are

int notes[][3] = {

{415, 0, 170},

{466, 170, 170},

{523, 340, 170},

{622, 511, 170},

{698, 852, 170},

{783, 1193, 170},

{698, 1363, 170},

{622, 1704, 170},

{523, 2045, 170},

{698, 2386, 170},

{622, 2727, 170},

{391, 3238, 170},

{415, 3409, 170},

{466, 3579, 170},

{523, 3750, 170},

{622, 3920, 170},

{698, 4261, 170},

{783, 4602, 170},

{698, 4772, 340},

{622, 5113, 340},

{587, 5454, 553},

{554, 6008, 42},

{523, 6051, 42},

{493, 6093, 42},

{466, 6136, 511},

{391, 6647, 340},

{523, 6988, 170},

{391, 7159, 170},

{523, 7329, 170},

{466, 7499, 511},

{391, 8011, 85},

{369, 8096, 85},

{349, 8181, 170},

{415, 8352, 170},

{622, 8522, 170},

{349, 8693, 170},

{415, 8863, 170},

{622, 9034, 170},

{349, 9204, 170},

{622, 9375, 85},

{622, 9545, 170},

{349, 9715, 170},

{622, 9886, 170},

{415, 10056, 170},

{391, 10227, 170},

{466, 10397, 170},

{391, 10568, 170},

{523, 10738, 170},

};

const int numNotes = sizeof(notes) / sizeof(notes[0]);

unsigned long songStartTime = 0;

int currentNote = 0;

int ADXL345 = 0x53; // The ADXL345 sensor I2C address

float v;

float X_out, Y_out, Z_out; // Outputs

float z_round;

const int buttonPin = 4; // Button to start/stop the motor

const int enA = 9; // PWM pin for motor speed control

const int in1 = 8; // Motor direction pin 1

const int in2 = 7; // Motor direction pin 2

const int speed = 60;

void setup() {

pinMode(buttonPin, INPUT_PULLUP);

pinMode(enA, OUTPUT);

pinMode(in1, OUTPUT);

pinMode(in2, OUTPUT);

pinMode(LED1, OUTPUT);

pinMode(LED2, OUTPUT);

pinMode(LED3, OUTPUT);

pinMode(LED4, OUTPUT);

pinMode(BUZZER_PIN, OUTPUT);

Serial.begin(9600);

/*

Initializing I2C Communication

@author: How to Mechatronics

(https://howtomechatronics.com/tutorials/arduino/how-to-track-orientation-with-arduino-and-adxl345-accelerometer/)

(https://www.youtube.com/channel/UCmkP178NasnhR3TWQyyP4Gw)

*/

Wire.begin(); // Initiate the Wire library

// Set ADXL345 in measuring mode

Wire.beginTransmission(ADXL345); // Start communicating with the device

Wire.write(0x2D); // Access/ talk to POWER_CTL Register - 0x2D

// Enable measurement

Wire.write(8); // (8dec -> 0000 1000 binary) Bit D3 High for measuring enable

Wire.endTransmission();

songStartTime = millis();

}

void loop() {

//Tick

tick++;

if (tick > speed){

tick = 0;

}

/*

I2C Communication

@author: How to Mechatronics

(https://howtomechatronics.com/tutorials/arduino/how-to-track-orientation-with-arduino-and-adxl345-accelerometer/)

(https://www.youtube.com/channel/UCmkP178NasnhR3TWQyyP4Gw)

*/

Wire.beginTransmission(ADXL345);

Wire.write(0x32); // Start with register 0x32 (ACCEL_XOUT_H)

Wire.endTransmission(false);

Wire.requestFrom(ADXL345, 6, true); // Read 6 registers total, each axis value is stored in 2 registers

delay(1); //delay ensures that i2c communication does not override serial communication

X_out = ( Wire.read()| Wire.read() << 8); // X-axis value

X_out = X_out/256; //For a range of +-2g, we need to divide the raw values by 256, according to the datasheet

Y_out = ( Wire.read()| Wire.read() << 8); // Y-axis value

Y_out = Y_out/256;

Z_out = ( Wire.read()| Wire.read() << 8); // Z-axis value

Z_out = Z_out/256;

if (Z_out <= -0.70) { // check for tilt on tilt sensor - this will need to be recalibrated depending on how it is oriented

playTune();

analogWrite(enA, 255); // Full speed for dc motor

muted = false; //unmute the buzzer

// //conditionals for lighting: turning on each LED

if (tick > 0 && tick < (speed/4)){

digitalWrite(LED1, HIGH);

digitalWrite(LED2, LOW);

digitalWrite(LED3, LOW);

digitalWrite(LED4, LOW);

}else if (tick >= (speed/4) && tick < (speed/2)){

digitalWrite(LED2, HIGH);

digitalWrite(LED1, LOW);

digitalWrite(LED3, LOW);

digitalWrite(LED4, LOW);

}else if (tick >= (speed/2) && tick < ((speed/4)*3)){

digitalWrite(LED3, HIGH);

digitalWrite(LED2, LOW);

digitalWrite(LED1, LOW);

digitalWrite(LED4, LOW);

}else{

digitalWrite(LED4, HIGH);

digitalWrite(LED2, LOW);

digitalWrite(LED3, LOW);

digitalWrite(LED1, LOW);

}

} else { // box has been opened: tilt up

digitalWrite(in1, LOW);

digitalWrite(in2, LOW);

analogWrite(enA, 0);

digitalWrite(LED2, LOW);

digitalWrite(LED1, LOW);

digitalWrite(LED3, LOW);

digitalWrite(LED4, LOW);

muted = true;

}

}

/*

function playTune

Plays a tune based off of the global 2D array

*/

void playTune() {

unsigned long currentMillis = millis(); // an unsigned long means there is no negative, doubling the amount of time

// the program can run without breaking

if (currentNote < numNotes && muted == false) { //check if muted and if still in limits of song

if ((currentMillis - songStartTime >= notes[currentNote][1])) {

tone(BUZZER_PIN, notes[currentNote][0], notes[currentNote][2]); //tone based on 2d array

currentNote++; // go to the next note

}

} else {

// restart song

currentNote = 0;

songStartTime = millis();

}

}

This project tested our ability to work with inputs and outputs in Arduino. Our initial design featured a music box that would spin faster when yelled at and slow down when clapped at. However, we found the microphone component unreliable—its amplitude fluctuations were inconsistent, and it wasn’t sensitive enough to detect short claps. Due to these limitations, we replaced sound-based input with movement and sought to amplify the output.

Ultimately, we pivoted to a new concept: a house that stops moving when the lid is opened, parodying the classic fridge light scenario. Initially, we considered using a photoresistor to detect light changes, but we needed an immediate response regardless of ambient conditions. A tilt sensor mounted on the roof proved to be a much more effective and accurate solution.

We also experimented with using 16 LEDs but found it overly complex in both coding and circuitry. Given how bright the LEDs were, we opted for just four—one of each color.

Another challenge was gear misalignment, which caused the machine to stop spinning when the spur teeth jammed. To resolve this, we added supports to keep the gears planar and running smoothly. Additionally, the magnetized dolls occasionally detached and stuck to each other, requiring manual resets. Future iterations could explore height variations between the planetary gear magnets and the dolls' feet or heads to prevent this issue.

In conclusion, we transitioned from a voice-activated music box to a more reliable motion-based system, refining both input methods and mechanical stability along the way.