Easy Expandable Alarm

This is an easy-to-make alarm that can easily be expanded with code to perform numerous functions. By itself, all you have to do is plug it in, and it will start ringing using the servo attached to the Arduino.

This project uses a scrap drive plate that has been cleaned and repurposed to create a makeshift bell. When the spring attached to the servo strikes the plate, it produces a reverberating ding that echoes for a few seconds before gradually dissipating.

Everything is held in place with a 3D-printed base, although it could have easily been made from a piece of wood and some glue.

Supplies include:

1. drive plate/other random metal scrap
2. Arduino uno
3. USB cable
4. 3 Jumper wires
5. Servo Motor
6. 3D printed arm/Spring
7. 3D printed base/Wooden Board
8. Hot glue/Hot glue gun

Once you have your key component, you will need to make the base. The component of your choice needs to be elevated above the base and should not be touching it.

The best option is to 3D-print the base, but a simple wooden board will work just as well, as long as it securely holds the component above the base.

Leave the rest aside for now. Take the Arduino Uno and attach the Power and Ground jumper wires to their corresponding inputs on the servo. There should be one wire left, which is the signal wire for the pin.

You can use any digital pin you want in the code, but I chose Pin 9 for this project. Attach Pin 9 to the remaining wire on the servo.

I will not explain how to code the servo in this guide, but it is fairly simple. With some help from AI, you could have the code written and working quickly. You can use the following prompt with an AI to generate the code:

“Write the code for an Arduino-controlled servo that goes from 0 degrees to 90 degrees. It needs to turn fast enough to ring a bell.”

The striking arm can be made from almost anything, but I found that metal worked best. For the most resounding sound, I recommend using a small spring or metal strip.

Once you have chosen your piece, securely attach it to the servo. Make sure to use a strong adhesive, as the striking arm will experience repeated movement and impact while the alarm is running.

The next step is to use hot glue or a suitable alternative to secure the electronics to the base. Preferably, do not glue the Arduino Uno directly to the base. Instead, use the pre-drilled screw holes to securely fasten it in place.

Position the servo so that when the striking arm moves downward, it makes contact with the metal component and produces a clear, resonating sound.

The last step is to connect the USB cable to the Arduino Uno and upload the code. To upload the code using the Arduino IDE, simply press the arrow-shaped Upload button. The code will then be uploaded to the Arduino through the USB cable.

Once this is done, the servo should begin striking the metal component, producing a ringing sound.

From here, you can expand the project with sensors, buttons, or other components to make the alarm more automatic and customizable.