diff --git a/examples/MQ-131/MQ-131.ino b/examples/MQ-131/MQ-131.ino
index c750e2e..5a17e04 100644
--- a/examples/MQ-131/MQ-131.ino
+++ b/examples/MQ-131/MQ-131.ino
@@ -27,6 +27,7 @@ MQUnifiedsensor MQ131(pin, type);
 float NOx, CL2, O3;
 
 void setup() {
+  Serial.begin(9600); //Init serial port
    //init the sensor
   /*****************************  MQInicializar****************************************
   Input:  pin, type 
@@ -53,8 +54,8 @@ void loop() {
 
   Serial.println("***************************");
   Serial.println("Lectures for MQ-131");
-  Serial.print("Volt: ");Serial.print(MQ9.getVoltage(false));Serial.println(" V"); 
-  Serial.print("R0: ");Serial.print(MQ9.getR0());Serial.println(" Ohm"); 
+  Serial.print("Volt: ");Serial.print(MQ131.getVoltage(false));Serial.println(" V"); 
+  Serial.print("R0: ");Serial.print(MQ131.getR0());Serial.println(" Ohm"); 
   Serial.print("NOx: ");Serial.print(NOx,2);Serial.println(" ppm");
   Serial.print("CL2: ");Serial.print(CL2,2);Serial.println(" ppm");
   Serial.print("O3: ");Serial.print(O3,2);Serial.println(" ppm");
diff --git a/examples/MQ-135/MQ-135.ino b/examples/MQ-135/MQ-135.ino
index 5fe43d2..7943c30 100644
--- a/examples/MQ-135/MQ-135.ino
+++ b/examples/MQ-135/MQ-135.ino
@@ -27,6 +27,7 @@ MQUnifiedsensor MQ135(pin, type);
 float CO, Alcohol, CO2, Tolueno, NH4, Acetona;
 
 void setup() {
+  Serial.begin(9600); //Init serial port
    //init the sensor
   /*****************************  MQInicializar****************************************
   Input:  pin, type 
@@ -56,8 +57,8 @@ void loop() {
 
   Serial.println("***************************");
   Serial.println("Lectures for MQ-135");
-  Serial.print("Volt: ");Serial.print(MQ8.getVoltage(false));Serial.println(" V"); 
-  Serial.print("R0: ");Serial.print(MQ8.getR0());Serial.println(" Ohm"); 
+  Serial.print("Volt: ");Serial.print(MQ135.getVoltage(false));Serial.println(" V"); 
+  Serial.print("R0: ");Serial.print(MQ135.getR0());Serial.println(" Ohm"); 
   Serial.print("CO: ");Serial.print(CO,2);Serial.println(" ppm");
   Serial.print("Alcohol: ");Serial.print(Alcohol,2);Serial.println(" ppm");
   Serial.print("CO2: ");Serial.print(CO2,2);Serial.println(" ppm");
diff --git a/examples/MQ-2/MQ-2.ino b/examples/MQ-2/MQ-2.ino
index a482bff..46a1772 100644
--- a/examples/MQ-2/MQ-2.ino
+++ b/examples/MQ-2/MQ-2.ino
@@ -27,8 +27,7 @@ MQUnifiedsensor MQ2(pin, type);
 float H2, LPG, CO, Alcohol, Propane, Benzene;
 
 void setup() {
-  //Init serial port
-  Serial.begin(115200);
+  Serial.begin(9600); //Init serial port
   /*****************************  MQInicializar****************************************
   Input:   
   Output:  
diff --git a/examples/MQ-3/MQ-3.ino b/examples/MQ-3/MQ-3.ino
index 42fcaf2..3116e35 100644
--- a/examples/MQ-3/MQ-3.ino
+++ b/examples/MQ-3/MQ-3.ino
@@ -17,7 +17,7 @@
 #include <MQUnifiedsensor.h>
 
 //Definitions
-#define pin A3 //Analog input 0 of your arduino
+#define pin A0 //Analog input 0 of your arduino
 #define type 3 //MQ3
 
 //Declare Sensor
@@ -27,7 +27,7 @@ MQUnifiedsensor MQ3(pin, type);
 float CH4, LPG, CO, Alcohol, Hexane, Benzine;
 
 void setup() {
-  Serial.begin(9600);
+  Serial.begin(9600); //Init serial port
   //init the sensor
   /*****************************  MQInicializar****************************************
   Input:  pin, type 
diff --git a/examples/MQ-303A/MQ303.ino b/examples/MQ-303A/MQ303.ino
index 3e910af..eb15f7d 100644
--- a/examples/MQ-303A/MQ303.ino
+++ b/examples/MQ-303A/MQ303.ino
@@ -27,6 +27,7 @@ MQUnifiedsensor MQ303(pin, type);
 float Iso_butano, Hydrogeno, Ethanol;
 
 void setup() {
+  Serial.begin(9600); //Init serial port
    //init the sensor
   /*****************************  MQInicializar****************************************
   Input:  pin, type 
@@ -52,9 +53,9 @@ void loop() {
   Ethanol =  MQ303.readSensor("Ethanol"); // Return Ethanol concentration
   
   Serial.println("***************************");
-  Serial.println("Lectures for MQ-135");
-  Serial.print("Volt: ");Serial.print(MQ8.getVoltage(false));Serial.println(" V"); 
-  Serial.print("R0: ");Serial.print(MQ8.getR0());Serial.println(" Ohm"); 
+  Serial.println("Lectures for MQ-303");
+  Serial.print("Volt: ");Serial.print(MQ303.getVoltage(false));Serial.println(" V"); 
+  Serial.print("R0: ");Serial.print(MQ303.getR0());Serial.println(" Ohm"); 
   Serial.print("Iso_butano: ");Serial.print(Iso_butano,2);Serial.println(" ppm");
   Serial.print("Hydrogeno: ");Serial.print(Hydrogeno,2);Serial.println(" ppm");
   Serial.print("Ethanol: ");Serial.print(Ethanol,2);Serial.println(" ppm");
diff --git a/examples/MQ-309A/MQ-309.ino b/examples/MQ-309A/MQ-309.ino
index e51b8db..03acf13 100644
--- a/examples/MQ-309A/MQ-309.ino
+++ b/examples/MQ-309A/MQ-309.ino
@@ -21,10 +21,13 @@
 #define type 309 //MQ309
 
 //Declare Sensor
-
 MQUnifiedsensor MQ309(pin, type);
 
+//Variables
+float H2, CH4, CO, Alcohol;
+
 void setup() {
+  Serial.begin(9600); //Init serial port
     //init the sensor
   /*****************************  MQInicializar****************************************
   Input:  pin, type 
@@ -42,11 +45,20 @@ void loop() {
   ************************************************************************************/ 
   //Read the sensor and print in serial port
   //Lecture will be saved in lecture variable
-  int lecture =  MQ309.readSensor("", true); // Return CO concentration
+  //float lecture =  MQ309.readSensor("", true); // Return CO concentration
   // Options, uncomment where you need
-  //int lecture =  MQ309.readSensor("H2", true); // Return H2 concentration
-  //int lecture =  MQ309.readSensor("CH4", true); // Return CH4 concentration
-  //int lecture =  MQ309.readSensor("CO", true); // Return CO concentration
-  //int lecture =  MQ309.readSensor("Alcohol", true); // Return Alcohol concentration
-  delay(400);
+  H2 =  MQ309.readSensor("H2"); // Return H2 concentration
+  CH4 =  MQ309.readSensor("CH4"); // Return CH4 concentration
+  CO =  MQ309.readSensor("CO"); // Return CO concentration
+  Alcohol =  MQ309.readSensor("Alcohol"); // Return Alcohol concentration
+
+  Serial.println("***************************");
+  Serial.println("Lectures for MQ-309");
+  Serial.print("Volt: ");Serial.print(MQ309.getVoltage(false));Serial.println(" V"); 
+  Serial.print("R0: ");Serial.print(MQ309.getR0());Serial.println(" Ohm"); 
+  Serial.print("H2: ");Serial.print(H2,2);Serial.println(" ppm");
+  Serial.print("CH4: ");Serial.print(CH4,2);Serial.println(" ppm");
+  Serial.print("CO: ");Serial.print(CO,2);Serial.println(" ppm");
+  Serial.print("Alcohol: ");Serial.print(Alcohol,2);Serial.println(" ppm");
+  Serial.println("***************************");  
 }
diff --git a/examples/MQ-4/MQ-4.ino b/examples/MQ-4/MQ-4.ino
index 629a30a..e476be8 100644
--- a/examples/MQ-4/MQ-4.ino
+++ b/examples/MQ-4/MQ-4.ino
@@ -27,6 +27,7 @@ MQUnifiedsensor MQ4(pin, type);
 float CH4, LPG, CO, Alcohol, smoke;
 
 void setup() {
+  Serial.begin(9600); //Init serial port
   //init the sensor
   /*****************************  MQInicializar****************************************
   Input:  pin, type 
diff --git a/examples/MQ-5/MQ-5.ino b/examples/MQ-5/MQ-5.ino
index c75dee5..3962726 100644
--- a/examples/MQ-5/MQ-5.ino
+++ b/examples/MQ-5/MQ-5.ino
@@ -27,6 +27,7 @@ MQUnifiedsensor MQ5(pin, type);
 float H2, LPG, CH4, CO, smoke;
 
 void setup() {
+  Serial.begin(9600); //Init serial port
    //init the sensor
   /*****************************  MQInicializar****************************************
   Input:  pin, type 
diff --git a/examples/MQ-6/MQ-6.ino b/examples/MQ-6/MQ-6.ino
index 1c143d5..a619b1c 100644
--- a/examples/MQ-6/MQ-6.ino
+++ b/examples/MQ-6/MQ-6.ino
@@ -27,6 +27,7 @@ MQUnifiedsensor MQ6(pin, type);
 float H2, LPG, CH4, CO, Alcohol;
 
 void setup() {
+  Serial.begin(9600); //Init serial port
   //init the sensor
   /*****************************  MQInicializar****************************************
   Input:  pin, type 
diff --git a/examples/MQ-7/MQ-7.ino b/examples/MQ-7/MQ-7.ino
index bda7d86..76f76b9 100644
--- a/examples/MQ-7/MQ-7.ino
+++ b/examples/MQ-7/MQ-7.ino
@@ -30,6 +30,7 @@ MQUnifiedsensor MQ7(pin, type);
 float H2, LPG, CH4, CO, Alcohol;
 
 void setup() {
+  Serial.begin(9600); //Init serial port
    //init the sensor
   /*****************************  MQInicializar****************************************
   Input:  pin, type 
diff --git a/examples/MQ-8/MQ-8.ino b/examples/MQ-8/MQ-8.ino
index ac18090..1070a32 100644
--- a/examples/MQ-8/MQ-8.ino
+++ b/examples/MQ-8/MQ-8.ino
@@ -27,6 +27,7 @@ MQUnifiedsensor MQ8(pin, type);
 float H2, LPG, CH4, CO, Alcohol;
 
 void setup() {
+  Serial.begin(9600); //Init serial port
    //init the sensor
   /*****************************  MQInicializar****************************************
   Input:  pin, type 
diff --git a/examples/MQ-9/MQ-9.ino b/examples/MQ-9/MQ-9.ino
index 9a55410..de3358c 100644
--- a/examples/MQ-9/MQ-9.ino
+++ b/examples/MQ-9/MQ-9.ino
@@ -27,6 +27,7 @@ MQUnifiedsensor MQ9(pin, type);
 float CO, CH4, LPG;
 
 void setup() {
+  Serial.begin(9600); //Init serial port
   //init the sensor
   /*****************************  MQInicializar****************************************
   Input:  pin, type 
diff --git a/examples/MQ-Board-Calibration/MQ-Board-Calibration.ino b/examples/MQ-Board-Calibration/MQ-Board-Calibration.ino
index 6164cd3..082110a 100644
--- a/examples/MQ-Board-Calibration/MQ-Board-Calibration.ino
+++ b/examples/MQ-Board-Calibration/MQ-Board-Calibration.ino
@@ -61,7 +61,7 @@ unsigned long time = millis();
 
 void setup() {
   //Init serial port
-  Serial.begin(115200);
+  Serial.begin(9600);
   // initialize the LCD
   lcd.begin();
   // Turn on the blacklight and print a message.
@@ -102,7 +102,16 @@ void setup() {
 }
 
 void loop() {
-
+  //Update the voltage lectures
+  MQ2.update();
+  MQ3.update();
+  MQ4.update();
+  MQ5.update();
+  MQ6.update();
+  MQ7.update();
+  MQ8.update();
+  MQ9.update();
+  
   //Read the sensor
   float lecture2 =  MQ2.calibrate();
   float lecture3 =  MQ3.calibrate();
diff --git a/examples/MQ-Board/MQ-Board.ino b/examples/MQ-Board/MQ-Board.ino
index 3888bf9..ffcca48 100644
--- a/examples/MQ-Board/MQ-Board.ino
+++ b/examples/MQ-Board/MQ-Board.ino
@@ -27,20 +27,21 @@
 #define pin9 A9 //Analog input 9 of your arduino
 
 //Declare Sensor
-
 MQUnifiedsensor MQ2(pin2, 2);
-MQUnifiedsensor MQ3(pin3, 2);
-MQUnifiedsensor MQ4(pin4, 2);
-MQUnifiedsensor MQ5(pin5, 2);
-MQUnifiedsensor MQ6(pin6, 2);
-MQUnifiedsensor MQ7(pin7, 2);
-MQUnifiedsensor MQ8(pin8, 2);
-MQUnifiedsensor MQ9(pin9, 2);
+MQUnifiedsensor MQ3(pin3, 3);
+MQUnifiedsensor MQ4(pin4, 4);
+MQUnifiedsensor MQ5(pin5, 5);
+MQUnifiedsensor MQ6(pin6, 6);
+MQUnifiedsensor MQ7(pin7, 7);
+MQUnifiedsensor MQ8(pin8, 8);
+MQUnifiedsensor MQ9(pin9, 9);
 
+//Variables
+float  LPG, Alcohol, CH4, H2, CH42, CO, H22, LPG2;
 
 void setup() {
   //Init serial port
-  Serial.begin(115200);
+  Serial.begin(9600);
   //init the sensor
   MQ2.inicializar(); 
   MQ3.inicializar(); 
@@ -55,15 +56,35 @@ void setup() {
 }
 
 void loop() {
+  //Update the voltage lectures
+  MQ2.update();
+  MQ3.update();
+  MQ4.update();
+  MQ5.update();
+  MQ6.update();
+  MQ7.update();
+  MQ8.update();
+  MQ9.update();
+  
   //Read the sensor and print in serial port
-  int lecture2 =  MQ2.read("", true);
-  int lecture3 =  MQ3.read("", true);
-  int lecture4 =  MQ4.read("", true);
-  int lecture5 =  MQ5.read("", true);
-  int lecture6 =  MQ6.read("", true);
-  int lecture7 =  MQ7.read("", true);
-  int lecture8 =  MQ8.read("", true);
-  int lecture9 =  MQ9.read("", true);
-  //Wait to measure next sample
-  delay(400);
+  LPG =  MQ2.readSensor();
+  Alcohol =  MQ3.readSensor();
+  CH4 =  MQ4.readSensor();
+  H2 =  MQ5.readSensor();
+  CH42 =  MQ6.readSensor();
+  CO =  MQ7.readSensor();
+  H22 =  MQ8.readSensor();
+  LPG2 =  MQ9.readSensor();
+
+  Serial.println("***************************");
+  Serial.println("Lectures for MQ-Board");
+  Serial.print("LPG: ");Serial.print(LPG,2);Serial.println(" ppm");
+  Serial.print("Alcohol: ");Serial.print(Alcohol,2);Serial.println(" ppm");
+  Serial.print("CH4: ");Serial.print(CH4,2);Serial.println(" ppm");
+  Serial.print("H2: ");Serial.print(H2,2);Serial.println(" ppm");
+  Serial.print("CH4_2: ");Serial.print(CH42,2);Serial.println(" ppm");
+  Serial.print("CO: ");Serial.print(CO,2);Serial.println(" ppm");
+  Serial.print("H2_2: ");Serial.print(H22,2);Serial.println(" ppm");
+  Serial.print("LPG_2: ");Serial.print(LPG2,2);Serial.println(" ppm");
+  Serial.println("***************************");  
 }
diff --git a/src/MQUnifiedsensor.h b/src/MQUnifiedsensor.h
index fb083cd..0989273 100644
--- a/src/MQUnifiedsensor.h
+++ b/src/MQUnifiedsensor.h
@@ -56,7 +56,7 @@
 /***********************Software Related Macros************************************/
 
 #define ADC_RESOLUTION 10 // for 10bit analog to digital converter.
-#define retries 50
+#define retries 5
 #define retry_interval 20
 
 /**********************Application Related Macros**********************************/