Tutorial: Breathalyzer using Alcohol Gas Sensor with Arduino

In this tutorial, we will demonstrate how to use the gas sensors and also how you can make a homemade Breathalyzer using an alcohol sensor, Arduino and LEDs

 

Material List

1x Arduino

1x Alcohol Sensor

1x Breadboard

7x LEDS

6x Resistor 330Ω

1x Resistor 10KΩ

Some jumpers

1. How it works

1.1) Gas Sensor

The gas sensor operates as potentiometer, but instead of get the resistance variation, we will take the variation of gas concentration(0d to 1023d).

1.2) LEDs (Bargraph)

Arduino will transform the variation of gas concentration, that ranging 0d to 1023, in a scale of 6 LEDs using the function map(maxreading01023, 0, qtyLED).

1.3) Adaptations

For this aplication we use a mouthwash, so we changed  the scale of (0d to 1023) to (0d to 200d), because the mouthwash not contain a high level of alcohol. So we use the funcion map(maxreading0200, 0, qtyLED).

2. The Sketch


#define qtyLED 6  //Declare the quantity of LED's for the bar graph
int LEDs[qtyLED]; //Array to store the states of the LEDs
int sensorPin = 0; //Variable that will hold the current value of the sensor
int time; //Variable that will hold the amount of time for the sensor to be read
int maxreading; //Variable to store the maximum value read during the last reading
//For loop counting variables
int i;
int j;
 
void setup()

  //Initialize the counting variables
  i=0;
  j=2;
  
  while(i < qtyLED) //While i is less than the number of defined LED's
  {                 //...save the value of i+2 in the LEDs array. we add 2 so that it represents one of our digital pins
    LEDs[i] = j;
    i++;
    j++;
  }
  
  for(i=0;i<qtyLED;i++) //Define the LED Pins as outputs. In this case 2->7
  {
    pinMode(LEDs[i], OUTPUT);
  }
  pinMode(13, OUTPUT); //Define pin 13 as an output so we can show when we are not taking a reading from the sensor(Blinkin
                       //...Or when we are taking a reading from the sensor (Solid)
}

void loop()
{
  PORTB = PORTB ^ 100000;  //Invert pin 13 to give the LED a blinking effect
  delay(100); //Delay so that the user can see the blinking happen
  int sensor = analogRead(sensorPin); //Read the sensors value and store it in the sensor variable
  if(sensor >= 40) //If the value is less that 40(value for the chemical being used in this example)
  {  
    digitalWrite(13, HIGH); //Turn on the blue LED indecating that the sensor detected a minimal amount of alcohol (sensor >= 40)
    maxreading = 0;         //Initiate the max reading to 0
    for(time = 0;time <= 5000;time++) //Read the sensor for 5 seconds
    {                                 //...every millisecond update the value of the max reading of the sensor
      int sensor = analogRead(sensorPin);
      delay(1);
      if(sensor > maxreading)
      {
        maxreading = sensor;
      }
    }
    digitalWrite(13, LOW); //As soon as the reading is complete turn off the blue LED
    int level = map(maxreading, 0, 200, 0, qtyLED); //Map the value from 0 to 200(reading from sensor) to 0 and the number of LEDs which is 6
                                                    //...0 to 6(LEDs) level determines how many of them turn on.
    for(i=0;i<qtyLED;i++) //Compare all the leds current state with the value of the level that was read
    {                     //if for example the level read was 5, then LEDs 2->6 would turn on.
      if (i < level) //If the current LED being checked is less that the level
      {
        digitalWrite(LEDs[i], HIGH); //...Turn it on
      }
      else //If the current LED being checked is higher than the level
      {
        digitalWrite(LEDs[i], LOW); //...Turn it off
      }
    }
    delay(10000); //Wait 10 seconds for the user to get the reading from the led bar graph
    for(i=0;i<qtyLED;i++) //Turn off all the LEDs
    {
      digitalWrite(LEDs[i],LOW);
    }
  }
}

3. The Circuit

Reference:

https://www.sparkfun.com/products/8880

Views: 4725

Tags: Alcohol, Arduino, Breathalyzer, Gas, Sensor

Comment

You need to be a member of GarageLab (arduino, electronics, robotics, hacking) to add comments!

Join GarageLab (arduino, electronics, robotics, hacking)

Latest Activity

GarageLab posted blog posts
yesterday
Profile IconOleg and Scott Runner joined GarageLab (arduino, electronics, robotics, hacking)
Thursday
GarageLab left a comment for RMullen
"Hi RMullen! I'd like to let you know that FRANK KWABENA is no longer a member of…"
Wednesday
daniel gabriel updated their profile
Wednesday
daniel gabriel left a comment for daniel gabriel
"Good Day Mr. Wabena, i dont see any interesting on my profile but i really appreciated that you…"
Wednesday
RMullen replied to Lauren Elizabeth's discussion Scammed...?
"Yes there is another one sending out the same message now.  This is the message I got: FRANK…"
Wednesday
Rick Lin is now a member of GarageLab (arduino, electronics, robotics, hacking)
Wednesday
GarageLab posted a blog post
Tuesday
Profile IconCalvin M and harsha joined GarageLab (arduino, electronics, robotics, hacking)
Tuesday
GarageLab posted a blog post

These Colorful Liquid Droplets Chase Each Other Like Living Organisms

Scientists at Stanford University were at first perplexed by the strange behavior they observed…See More
Monday
GarageLab posted blog posts
Mar 20
Profile IconJody Bowie, Kevin Kvarda, Tony Stoklosa and 2 more joined GarageLab (arduino, electronics, robotics, hacking)
Mar 19
Sergey commented on GarageLab's blog post Tutorial: How to use the Monster Moto Shield
"Good day. Can you help me? I took this sketch, but it doesn't working( "
Mar 19
Profile IconDonald Soji Adedokun, Ankur Deo and Hannu Miettinen joined GarageLab (arduino, electronics, robotics, hacking)
Mar 18
GarageLab posted a blog post
Mar 18
GarageLab posted a blog post

Iron Man Delivers Kid’s Robotic Arm: Proof that Tony Stark Has a Heart

Alex Pring now has one heck of a story to tell his friends. Not only did the 7-year old meet Iron…See More
Mar 16
Profile IconJohn Murphy and Asma Ho joined GarageLab (arduino, electronics, robotics, hacking)
Mar 16
Electronicsrus is now a member of GarageLab (arduino, electronics, robotics, hacking)
Mar 13
AnalysIR commented on GarageLab's blog post Tutorial: Arduino IR sender and receiver
"@kkukkuk this problem has been discussed receltly on the Arduino forum - why not search there. You…"
Mar 13
kkukkuk commented on GarageLab's blog post Tutorial: Arduino IR sender and receiver
"hi..there are some errors in both irsend and irreceive coding.. ir sender: sketch_mar14a.ino:17:1:…"
Mar 13

© 2015   Created by Marcelo Rodrigues.

Badges  |  Report an Issue  |  Terms of Service