Simple Arduino Breathalyzer

Simple Arduino Breathalyzer

 Introduction

The MQ series of gas sensors use a small heater inside with an electro-chemical sensor.
They can be calibrated more or less but a know concentration of the measured gas or gasses is needed for that. 
 They are sensitive for a range of gasses and are used indoors at room temperature.
The output is an analog signal and can be read with an analog input of the Arduino. 

SainSmart MQ-3
The analog gas sensor - MQ3 is used in gas leakage detecting equipments in consumer and industry markets, this sensor is suitable for detecting LPG, i-butane, propane, methane ,alcohol, Hydrogen, smoke.
It has a high sensitivity and fast response time.And the sensitivity can be adjusted by the potentiometer.

 The MQ-3 is an alcohol gas sensor that is available for about $5.

 Connetting

 Sensor-Arduino 

    GND - GND
    A0   -  A0
    VCC -   5V


Arduino Schetch

Test Code: 


int val=0;

void setup(){

Serial.begin(9600);
}

void loop(){

val=analogRead(A0);

Serial.println(val);

delay(100);
}

Link App

https://drive.google.com/file/d/1naIS3WD_Boty_EjX_9em6Vw1NMy59dps/view?usp=sharing

Arduino Tutorial - Easy secret knock detector

In this project I build a circuit with a Led and a piezo to function as a on and off a Led when it receives a number of knocking sounds within a given range.

Step 1: Things you need

 Hardware

• LED
• Diode(Zener 5.1v).
• Piezo Buzzer
• 470Ω Resistor
• 1MΩ Resistor
• Arduino uno
• jumper wire
• Breadboard

Software

• Arduino IDE

Step 2: Watch the video tutorial

Step 3: Schematics

 

The circuit is so simple:
Arduino Pins: Breadboard:
Pin A2 --------------------------1MΩ-------------------Gnd
Pin A2 ------------------------Diode-------------------Gnd
Pin A2 ------------------Piezo Buzzer---------------Gnd
Pin 8 -------------------------470Ω-------Led 1------Gnd
Gnd-------------------------------------------------------Gnd

Step 4: Arduino Sketch

"const int outputPin = 5; // led indicator connected to digital pin const int knockSensor = A2; // the piezo is connected to an analog pin const int thresholdHIGH =120; // threshold value to decide when the detected knock is hard (HIGH) const int thresholdLOW = 70; // threshold value to decide when the detected knock is gentle (LOW) const int secretKnockLength = 3; //How many knocks are in your secret knock /* This is the secret knock sequence * 0 represents a LOW or quiet knock * 1 represents a HIGH or loud knock * The sequence can be as long as you like, but longer codes increase the difficulty of matching */ const int secretKnock[secretKnockLength] = {0, 0, 1}; int secretCounter = 0; //this tracks the correct knocks and allows you to move through the sequence int sensorReading = 0; // variable to store the value read from the sensor pin void setup() { //Set the output pin as an OUTPUT pinMode(outputPin, OUTPUT); //Begin Serial Communication. Serial.begin(9600); } void loop() { // read the piezo sensor and store the value in the variable sensorReading: sensorReading = analogRead(knockSensor); // First determine is knock if Hard (HIGH) or Gentle (LOW) //Hard knock (HIGH) is detected if (sensorReading >= thresholdHIGH) { //Check to see if a Hard Knock matches the Secret Knock in the correct sequence. if (secretKnock[secretCounter] == 1) { //The Knock was correct, iterate the counter. secretCounter++; Serial.println("Correct"); } else { //The Knock was incorrect, reset the counter secretCounter = 0; Serial.println("Fail"); digitalWrite(outputPin, LOW); }//close if //Allow some time to pass before sampling again to ensure a clear signal. delay(100); //Gentle knock (LOW) is detected } else if (sensorReading >= thresholdLOW) { //Check to see if a Gentle Knock matches the Secret Knock in the correct sequence. if (secretKnock[secretCounter] == 0) { //The Knock was correct, iterate the counter. secretCounter++; Serial.println("Correct"); } else { //The Knock was incorrect, reset the counter. secretCounter = 0; Serial.println("Fail"); }//close if //Allow some time to pass before sampling again to ensure a clear signal. delay(100); }//close if else //Check for successful entry of the code, by seeing if the entire array has been walked through. if (secretCounter == (secretKnockLength) ) { Serial.println("Welcome"); //if the sececret knock is correct, illuminate the LED for a couple seconds digitalWrite(outputPin, HIGH); //Reset the secret counter to 0. secretCounter = 0; }//close success check }//close loop".

 

How to use MQ7 gas sensors whith Arduino+Android App

In this project show you, how receive MQ7 data from arduino with your android phone. Carbon monoxide(CO) is a very dengerous gas which is odorless, colorless. CO is produced from the partial oxidation of carbon dioxide, such as when operrating a stove or an internal combustion engine in an enclosed space.

Step 1:Components Needed

Hardware

• Bluetooth
• ModuleMQ7-Sensor
• Breadboard
• Arduino Uno
• Jumper Wire

Software

• Arduino IDE
• App Inventor 2 (for create your app).

 Step 2: Watch the video tutorial

The circuit is so simple:

Arduino Pins: -------------------------- Bluetooth Module:
RX (Pin 0)----------------------------------------TX
TX (Pin 1)-----------------------------------------RX
5v---------------------------------------------------5v
Gnd-------------------------------------------------Gnd
Pin2,Gnd------------------------------------------Gnd
Arduino Pins: -------------------------- MQ-7(CO Sensor):

Vcc ------------------------------------------- 5V pin
GND ------------------------------------------ GND pin
A_Out ----------------------------------------- A0 pin
D_Out ----------------------------------------- pin 8.
HC-06 Bluetooth
Notes and Tips: You need to remove the RX and TX cables when you’re uploading the sketch to your Arduino. If the HC-06 Bluetooth Module asks for a password, It’s’1234′. Sometimes people connect the TX from the bluetooth module to the TX of the Arduino… that’s wrong and it won’t work. Make sure you connect it properly, the TX into RX and the RX into the TX.

Step 4: Arduino Sketch

const int AOUTpin=0;//the AOUT pin of the CO sensor goes into analog pin A0 of the arduino
const int DOUTpin=8;//the DOUT pin of the CO sensor goes into digital pin D8 of the arduino const int ledPin=13;//the anode of the LED connects to digital pin D13 of the arduino
int limit; int value;
void setup() { Serial.begin(9600);//sets the baud rate pinMode(DOUTpin, INPUT);//sets the pin as an input to the arduino pinMode(ledPin, OUTPUT);//sets the pin as an output of the arduino }
void loop() { value= analogRead(AOUTpin);//reads the analaog value from the CO sensor's AOUT pin limit= digitalRead(DOUTpin);//reads the digital value from the CO sensor's DOUT pin Serial.print("CO value: "); Serial.println(value);//prints the CO value Serial.print("Limit: "); Serial.print(limit);//prints the limit reached as either LOW or HIGH (above or underneath) delay(100); if (limit == HIGH){ Serial.println("Bad"); } else{ Serial.println("OK"); } }