Red Balloon - How Does It Work?




Introduction: Red Balloon - How Does It Work?

The carbon monoxide sensor detects high levels of CO-gas concentrations in the air. When the concentration reaches a high level (which we pre-set) the LED changes color from green to red.

Step 1: Getting the Components

Click on the magic link to and the components will alreadyt be pre-selected for you: carbon monoxide sensor, RGB Led common anode, Arduino Uno and a 4 AA battery case.

You can use a different controller and power supply but make sure you change the code accordingly.

Apart from these components, you’ll also need peripherals such as jumper wires, a few different resistors, a breadboard and a few other things, and they will all be listed for you in the BoM section of the reply

Step 2: Assembling the Circuit

Once you have all the components, you can start putting the circuit together according to the step-by-step wiring guide in the reply.

In addition to the step by step guide, also make sure to:

1. Solder the MQ7 sensor to the breakout board. On Step-by-Step the MQ7 sensor is currently not sitting directly on the breadboard. We recommend that at first, you connect it directly to the board (as you can see in the image above). After you test with the code (in step #3 - Coding) that everything is up and running, you can connect the MQ7 sensor to the ribbon as described here below.

2. Solder a 4 or 6 wire ribbon to the Q7 sensor. We used a 15 feet ribbon (approx. 5 meters).

3. You can use crimps at the tips of the ribbon to connect them to the breadboard. Generally we like to use these instead of soldering. You can buy a kit such as this one, it’s super handy.

Step 3: Coding

  1. Download the code and extract it to your computer.
  2. Next, open it with the Arduino IDE, and make sure that the port and board (Arduino Uno) are selected properly, then upload the code to the Arduino.
  3. If the code is working, you need to replace the code you got from with the code below, since this is the specific code for the project.

If you've never used Arduino before, follow the steps below: Download this software, which can be used with any Arduino board.

Refer to the Getting Started page for Installation instructions.

 #include "Global.h"

void setup() {
  // Setup Serial which is useful for debugging
  // Use the Serial Monitor to view printed messages


void loop() {

  int val =;
  val = map(val, 40, 120, 0, 255);
  Serial.print("  val:");

  // Change the rgb colors with an interval of 500ms
  rgbLed.setRGB(255 - val, val, 0);



Step 4: Buy a Balloon and You’re Ready to Go!

Last but not least, find a place that sells helium balloons near your house. It doesn't have to be red :)

Connect the MQ7 sensor to the balloon (zip-ties are the easiest way to do this), and start monitoring the air quality around you.

We hope you’ll be pleasantly surprised.

Step 5: Have Any Questions? Want to Start Your Own Project?

We are more than happy to answer your questions.

Just shoot us an email: or find us on facebook.

If you already have an idea for a new project, you can start right away by submitting the basic components on and we’ll do the rest. Don’t forget to share your creation on our facebook page.

Enjoy Making!



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