Introduction: Fire Alarm

About: Teaching and making electronics since - well I don't even know

This is not a drill! Because it's a fire (to be more specific, flame) alarm.

No one cares about fire alarms (or any alarm) anymore. Yepp, annoying things interrupting our cooking, or the neighbor's car is being stolen? All we hear is beep-beep-beep, and we just ignore it. (and to be honest, it's pretty sad)

Let's make a fire alarm WHICH DOESN'T SUBSTITUTE A REAL FIRE ALARM! This is a fun project, DON'T RISK ANYONE's LIFE!

But add a little twist, shall we? Yes, we could only beep, but make it just a little bit more foolproof and fun.



DF Player mini + speaker


flame sensor

LEDs + resistor

passive buzzer

Step 1: The Circuit

What is cannot be seen: the DF Player needs some power to play sounds, so try to use an external USB power! (I can't find a proper symbol in Fritzing, sorry)

We have 2 LEDs for visual warning, one button for confirming the alarm and entering test mode, one music player part and one buzzer. On the far right you can see the flame sensor - either get a module or make it with a LED + 100k resistor by yourself.

Since the sensor produces an analog signal, proper calibration is mandatory! Also it doesn't sense in all direction, it has a ~30° cone where it works. It sensed a candle from 3-4 meters.

Step 2: The Code

The Internet provides us useful sites where we can share our code. This time it's not GitHub.

I made this project with kids in a summer camp, so we had to brainstorm a bit. First of all, a proper fire alarm shall not be silenced if there is fire - if the flame sensor senses a fire, it will beep, no matter how hard you push the button.

The other idea was a test mode - push the button 3 seconds long and it will do an alarm test. Not releasing it will result in a constant beep - because a broken button is an error too!

Other safety test like selftest is missing - it's a fun project, not a professional fire alarm! (oh, when you see flames, it's a bit late, smoke alarms are a thing for a reason)

Step 3: Fire!

The DF Player needs a 0001.mp3 file in the microSD card's root folder. And what should that file be? Watch the video! (and of course, because of copyright reasons, I'm not allowed to share the Gem)

I hope it made you at least chuckle. This project is a kind reminder: not everything must be super serious, have fun sometimes! Thanks for reading!

Audio Challenge 2020

Participated in the
Audio Challenge 2020