diff --git a/examples/MQ-Board-Calibration/MQ-Board-Calibration.ino b/examples/MQ-Board-Calibration/MQ-Board-Calibration.ino
index 1871cdb..0f31b6d 100644
--- a/examples/MQ-Board-Calibration/MQ-Board-Calibration.ino
+++ b/examples/MQ-Board-Calibration/MQ-Board-Calibration.ino
@@ -17,6 +17,10 @@
   modified 28 May 2019
   by Ghiordy contreras, Miguel Califa 
 
+  Added voltaje to log
+  modified 29 May 2019
+  by Miguel Califa 
+  
  This example code is in the public domain.
 
 */
@@ -44,15 +48,16 @@ LiquidCrystal_I2C lcd(0x27, 16, 2);
 //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);
 
 unsigned long contador = 0;
+unsigned long time = millis();
 
 void setup() {
   //Init serial port
@@ -66,7 +71,7 @@ void setup() {
   lcd.setCursor(0,0);
   lcd.print("MQ2 to MQ9");
   lcd.setCursor(0,1);
-  lcd.print("   Calibracion");
+  lcd.print("   Calibrating");
   //init the sensor
   
   MQ2.inicializar(); 
@@ -77,11 +82,20 @@ void setup() {
   MQ7.inicializar(); 
   MQ8.inicializar(); 
   MQ9.inicializar();
+
+  MQ2.setVoltResolution(5);
+  MQ3.setVoltResolution(5);
+  MQ4.setVoltResolution(5);
+  MQ5.setVoltResolution(5);
+  MQ6.setVoltResolution(5);
+  MQ7.setVoltResolution(5);
+  MQ8.setVoltResolution(5);
+  MQ9.setVoltResolution(5);
   
   //Print in serial monitor
   Serial.println("MQ2 to MQ9 - Calibracion");
   Serial.println("Note - Make sure you are in a clean room and the sensor has pre-heated almost 4 hours");
-  Serial.println("Autonumeric, MQ2(PPM), MQ3(PPM), MQ4(PPM), MQ5(PPM), MQ6(PPM), MQ7(PPM)");
+  Serial.println("Autonumeric, MQ2(R0), MQ3(R0), MQ4(R0), MQ5(R0), MQ6(R0), MQ7(R0)");
   //Wait one second to continue
   delay(timeDelay/10);
 }
@@ -96,6 +110,7 @@ void loop() {
   int lecture7 =  MQ7.calibrate();
   int lecture8 =  MQ8.calibrate();
   int lecture9 =  MQ9.calibrate();
+
   
   //Print in serial monitor
   char out[40];
@@ -105,47 +120,11 @@ void loop() {
   //Print in LCD
   lcd.clear();
   lcd.setCursor(0,0);
-  lcd.print("MQ2: ");
-  lcd.print(lecture2);
-  lcd.print(" PPM");
+  lcd.print("**CALIBRATING***");
   lcd.setCursor(0,1);
-  lcd.print("MQ3: ");
-  lcd.print(lecture3);
-  lcd.print(" PPM");
-  delay(timeDelay/4);
-  lcd.clear();
-  lcd.setCursor(0,0);
-  lcd.print("MQ4: ");
-  lcd.print(lecture4);
-  lcd.print(" PPM");
-  lcd.setCursor(0,1);
-  lcd.print("MQ5: ");
-  lcd.print(lecture5);
-  lcd.print(" PPM");
-  delay(timeDelay/4);
-  lcd.clear();
-  lcd.setCursor(0,0);
-  lcd.print("MQ6: ");
-  lcd.print(lecture6);
-  lcd.print(" PPM");
-  lcd.setCursor(0,1);
-  lcd.print("MQ7: ");
-  lcd.print(lecture7);
-  lcd.print(" PPM");
-  delay(timeDelay/4);
-  lcd.clear();
-  lcd.setCursor(0,0);
-  lcd.print("MQ8: ");
-  lcd.print(lecture2);
-  lcd.print(" PPM");
-  lcd.setCursor(0,1);
-  lcd.print("MQ8: ");
-  lcd.print(lecture8);
-  lcd.print(" PPM");
-  delay(timeDelay/4);
-
+  lcd.print("Time: " + String((millis() - time)/60000) + "min");
   //Increment counter
   contador++;
   //Wait to measure next sample
   delay(timeDelay/4);
-}
+}
\ No newline at end of file
diff --git a/src/MQUnifiedsensor.cpp b/src/MQUnifiedsensor.cpp
index bc94ed0..91c051f 100644
--- a/src/MQUnifiedsensor.cpp
+++ b/src/MQUnifiedsensor.cpp
@@ -92,7 +92,7 @@
 }
 void MQUnifiedsensor::setVoltResolution(float voltaje)
 {
-  VOLT_RESOLUTION = voltaje;
+  _VOLT_RESOLUTION = voltaje;
 }
 void MQUnifiedsensor::inicializar()
 {
@@ -125,8 +125,6 @@ void MQUnifiedsensor::setSensorCharacteristics(String nameLectureRequeired, bool
   {
     //Set default
     setDefaultGas();
-    //Set ratio in clean air to calc R0
-    setRatioInCleanAir();
     //Put  the default into variable internally used
     nameLectureRequeired = _nameLectureRequeired;
   }
@@ -151,7 +149,7 @@ int MQUnifiedsensor::readPPM(int m, int b) {
   _sensor_volt = this->getVoltage();
   double RS_gas; //Define variable for sensor resistance
 
-  RS_gas = ((VOLT_RESOLUTION*RLValue)/_sensor_volt)-RLValue; //Get value of RS in a gas
+  RS_gas = ((_VOLT_RESOLUTION*_RLValue)/_sensor_volt)-_RLValue; //Get value of RS in a gas
 
   _ratio = RS_gas / this->_R0;   // Get ratio RS_gas/RS_air
 
@@ -177,7 +175,7 @@ int MQUnifiedsensor::calibrate() {
   float R0; //Define variable for R0
   float sensorValue; //Define variable for analog readings
   _sensor_volt = this->getVoltage(); //Convert average to voltage
-  RS_air = ((VOLT_RESOLUTION*RLValue)/_sensor_volt)-RLValue; //Calculate RS in fresh air 
+  RS_air = ((_VOLT_RESOLUTION*_RLValue)/_sensor_volt)-_RLValue; //Calculate RS in fresh air 
   R0 = RS_air/_ratioInCleanAir; //Calculate R0 
   return R0;
 }
@@ -188,7 +186,7 @@ double MQUnifiedsensor::getVoltage() {
     delay(retry_interval);
   }
 
-  double voltage = avg * VOLT_RESOLUTION / (pow(2, ADC_RESOLUTION) - 1);
+  double voltage = avg * _VOLT_RESOLUTION / (pow(2, ADC_RESOLUTION) - 1);
 
   return voltage;
 }
diff --git a/src/MQUnifiedsensor.h b/src/MQUnifiedsensor.h
index e159386..9d8aa14 100644
--- a/src/MQUnifiedsensor.h
+++ b/src/MQUnifiedsensor.h
@@ -8,14 +8,6 @@
 //Count of posible lectures
 #define lecturesAvailable 19
 
-/************************Global vars************************************/
-int VOLT_RESOLUTION  = 5.0; // if 3.3v use 3.3
-int RLValue = 10; //Value in KiloOhms
-int  _ratioInCleanAir, _PPM, _sensor_volt;
-double RS_air, _m, _b, _ratio;
-
-/************************Hardware Related Macros************************************/
-
 //Index in the nameLecture vector
 #define defaultMQ2 "LPG" // LPG
 #define defaultMQ3 "Alcohol" // Alcohol
@@ -68,18 +60,18 @@ double RS_air, _m, _b, _ratio;
 /**********************Application Related Macros**********************************/
 /* Gas, Value of m (Slope) and b (Cut on x axis) points */
 //Values consolidated
-const String PROGMEM _MQ2[18] = {"H2","-2.2459","2.9845","LPG","-2.2879","2.7901","CO","-2.6208","3.6075","Alcohol","-3.1157","4.5134","Propane","-2.7028","3.5595","Benzene","-2.2879","2.7901"};
-const String PROGMEM _MQ3[18] = {"LPG","-3.1851","4.7048","CH4","-17.531","28.785","CO","-4.339","6.4432","Alcohol","-1.435","0.4103","Benzene","-2.7009","0.632","Hexane","-2.7268","3.6299"};
-const String PROGMEM _MQ4[15] = {"LPG","-2.5818","3.6303","CH4","0.9873","2.6386","CO","-5.5945","5.6693","Alcohol","-11.89","9.0375","smoke","-11.189","9.0375"};
-const String PROGMEM _MQ5[15] = {"H2","-4.368","2.9667","LPG","-2.5723","1.8943","CH4","-2.4438","2.3044","CO","-4.8188","5.2023","Alcohol","-4.419","4.8044"};
-const String PROGMEM _MQ6[15] = {"H2","-3.6775","5.0286","LPG","-1.6567","2.8775","CH4","-1","3.301","CO","-12.791","14.523","Alcohol","-5.8057","7.5292"};
-const String PROGMEM _MQ7[15] = {"H2","-1.329","1.8864","LPG","-7.8626","9.1056","CH4","-5.4878","8.8387","CO","-1.4065","2.0162","Alcohol","-6.3219","9.924"};
-const String PROGMEM _MQ8[15] = {"H2","-0.7152","2.9891","LPG","-3.419","7.3513","CH4","-7.5609","15.243","CO","-7.0753","15.396","Alcohol","-1.7459","4.7575"};
-const String PROGMEM _MQ9[9] = {"LPG","-2.2535","2.9855","CH4","-1.6012","3.1476","CO","-1.749","2.827"};
-const String PROGMEM _MQ131[9] = {"Nox","-2.7245","3.3004","CL2","-1.0333","1.7117","O3","-1.2037","1.6455"};
-const String PROGMEM _MQ135[18] = {"CO","-2.7268","2.301","Alcohol","-2.8608","1.8627","CO2","-3.2819","1.9903","Tolueno","-5.7015","1.1612","NH4","-2.2119","2.0473","Acetona","-5.9682","1.0175"};
-const String PROGMEM _MQ303A[9] = {"Iso-butano","-2.3543","1.144","Hydrogeno","-2.4338","0.7558","Ethanol","-2.5597","0.4436"};
-const String PROGMEM _MQ309A[12] = {"H2","-2.1311","3.0886","CH4","-1.6554","2.985","CO","-4.7623","6.7413","Alcohol","-3.7686","5.6744"};
+const String _MQ2[18] = {"H2","-2.2459","2.9845","LPG","-2.2879","2.7901","CO","-2.6208","3.6075","Alcohol","-3.1157","4.5134","Propane","-2.7028","3.5595","Benzene","-2.2879","2.7901"};
+const String _MQ3[18] = {"LPG","-3.1851","4.7048","CH4","-17.531","28.785","CO","-4.339","6.4432","Alcohol","-1.435","0.4103","Benzene","-2.7009","0.632","Hexane","-2.7268","3.6299"};
+const String _MQ4[15] = {"LPG","-2.5818","3.6303","CH4","0.9873","2.6386","CO","-5.5945","5.6693","Alcohol","-11.89","9.0375","smoke","-11.189","9.0375"};
+const String _MQ5[15] = {"H2","-4.368","2.9667","LPG","-2.5723","1.8943","CH4","-2.4438","2.3044","CO","-4.8188","5.2023","Alcohol","-4.419","4.8044"};
+const String _MQ6[15] = {"H2","-3.6775","5.0286","LPG","-1.6567","2.8775","CH4","-1","3.301","CO","-12.791","14.523","Alcohol","-5.8057","7.5292"};
+const String _MQ7[15] = {"H2","-1.329","1.8864","LPG","-7.8626","9.1056","CH4","-5.4878","8.8387","CO","-1.4065","2.0162","Alcohol","-6.3219","9.924"};
+const String _MQ8[15] = {"H2","-0.7152","2.9891","LPG","-3.419","7.3513","CH4","-7.5609","15.243","CO","-7.0753","15.396","Alcohol","-1.7459","4.7575"};
+const String _MQ9[9] = {"LPG","-2.2535","2.9855","CH4","-1.6012","3.1476","CO","-1.749","2.827"};
+const String _MQ131[9] = {"Nox","-2.7245","3.3004","CL2","-1.0333","1.7117","O3","-1.2037","1.6455"};
+const String _MQ135[18] = {"CO","-2.7268","2.301","Alcohol","-2.8608","1.8627","CO2","-3.2819","1.9903","Tolueno","-5.7015","1.1612","NH4","-2.2119","2.0473","Acetona","-5.9682","1.0175"};
+const String _MQ303A[9] = {"Iso-butano","-2.3543","1.144","Hydrogeno","-2.4338","0.7558","Ethanol","-2.5597","0.4436"};
+const String _MQ309A[12] = {"H2","-2.1311","3.0886","CH4","-1.6554","2.985","CO","-4.7623","6.7413","Alcohol","-3.7686","5.6744"};
 
 class MQUnifiedsensor
 {
@@ -103,8 +95,14 @@ class MQUnifiedsensor
     
 
   private:
-    int _pin, _type, _R0; 
+    /************************Private vars************************************/
+    int _pin, _type, _R0, _lecturePosInArray; 
     String _MQ[19], _nameLectureRequeired;   
+    int _VOLT_RESOLUTION  = 5.0; // if 3.3v use 3.3
+    int _RLValue = 10; //Value in KiloOhms
+    int  _ratioInCleanAir, _PPM, _sensor_volt;
+    float RS_air, _m, _b, _ratio;
+    
 };
 
 #endif //MQUnifiedsensor_H
\ No newline at end of file