Introduction: Bathroom Alarm

The Emergency Potty Alarm is perfect for anyone who regularly goes through the discomfort and frantic suspense of waiting for someone to get out of the bathroom when desperately in need of a toilet. The Emergency Potty Alarm system has a push button located just outside the bathroom door. When the button is pushed, an alarm sounds inside the bathroom, alerting the occupant that someone is desperately waiting. The alarm turns off automatically once the door is opened.


Step 1: Components

Circuit Components

Arduino (I used the Arduino Uno)


Resistors: 1x (brown blue green), 2x (brown black orange), 1x (red, red, red)


Massive Arcade Button

Magnetic Door Switch


Wires - 4 Different Colors (I used red, black, yellow, and green)

12V DC Power Adapter

4-Way DC Power Splitter (You only use two of the splitters, so use a 2-Way splitter if you have one).

Breadboard-Friendly DC Barrel Jack

Soldering Equipment

Suggested Box Components - Laser cutter required

12" x 18" 1/8 White Acrylic


3M Removable Mounting Squares

Alligator Clips

Electrical Tape

Measuring Tape

Masking Tape optional

Box to house circuit (I used a box I found around the house)

Method to Make Vinyl Stickers (I used an Epson Vinyl Printer Cutter)

Step 2: Code and Circuit

The code is fairly straightforward.

Notes on Wiring

Door Switch

The door switch can be thought of as a button for wiring and coding purposes. It uses a pull-up resistor. It does not matter which wire goes to positive or negative.

Massive Arcade Button

The button has two prongs for the LED and two prongs for the button. The two prongs on the sides are for the LED, and the two uneven prongs are for the button. For the button function, the protruding prong is positive, and the inset pin is negative.

It's easiest to color code each of the prongs with a different colored wire. I used:

Red: LED Power - to Pin 7

Black: LED Ground - to ? k resistor

Yellow: Button Power - to ? k resistor

Green: Button Ground - to ground

Step 3: Making the Box

Design box and laser cut it! There are a lot of great websites that generate box plans for free. I used and then added a hole to screw in the button and a wire hole. I've attached the file I used, but it could use some tinkering.

To attach the button to the box face, remove the washer from the back of the button. Slide in the wall, and screw the washer in on top.

Glue the box together along the seams, with the exception of the button face. DO NOT GLUE ON THE BUTTON FACE.

Put the wires through the wire hole on the bottom face. Snap the top face in.

Step 4: Reducing Siren Volume

If the siren sounds a little too loud, which it might, you can unscrew the bottom, and place masking tape over the speaker.

Step 5: Measuring and Soldering

Figure out where you want to place the front button, the siren, and locate the power outlet that will charge the Bathroom Alarm. There is typically more space under the door, so measure for the wires going under the door.

It's easiest to make the wires longer than you think you will need, and then trim them at the end.

Solder the wires appropriately. Make sure to wrap the individual siren wires in electrical tape to keep them from shorting.

Bundle the wires for each of the sensors by wrapping them in electrical tape every few inches.

Once the circuit is working correctly, use electrical tape along the button box to add a decorative element and secure the front face.

Step 6: Stickers!

Print and attach stickers to button and alarm. (File coming shortly).

Step 7: Mounting

For a quick, temporary, and damage free solution, you can use Scotch Temporary Mounting Squares. Each pack has 64 squares, so you only need to buy one pack.

Adhere the following number of mounting squares:

2 each for door sensors

8 for alarm

16 for button

Step 8: Box for Circuit

If desired, get a box and drill holes appropriately for your setup. I used a cardboard jewelry box.

Step 9: Finishing Touches

Tape wires along the wall using electrical tape.

Admire your handiwork.