Arduino MEGA + Rain sensor

Other Hardware Sensors
1

Dear, I am using this sensor: Rain sensor. Rain

Now, I've been testing it and I'm having problems with the night dew, the sensor by logic and it senses values ​​like it's raining ...

What can be done??? the respect ?? any ideas?? I am using this code:

void llueve(){
  llueveAux = 0;
  Serial.println(analogRead(A0)); //lectura analógica
  Serial.println(digitalRead(2)); //lectura digital
  Alarm.delay(100);
  valorLluvia = analogRead(A0);
 

  if (valorLluvia < 400){
    //nivelLluvia = "Lluvia Nivel: FUERTE " + valorLluvia;
    nivelLluvia = valorLluvia;
    Serial.println("Lluvia Nivel: FUERTE");
    //esta lloviendo   leve 
    llueveAux = 1;
  } 

  if (valorLluvia >400 && valorLluvia <700){
    //nivelLluvia = "Lluvia Nivel: MEDIO "+ valorLluvia;
    Serial.println("Lluvia Nivel: MEDIO");
    nivelLluvia = valorLluvia;
    //esta lloviendo  medio
    llueveAux = 1;  
  } 

  if (valorLluvia > 700 && valorLluvia <900){
    nivelLluvia = "Lluvia Nivel: LEVE ";
    Serial.println("Lluvia Nivel: LEVE");
    nivelLluvia = valorLluvia;
    //esta lloviendo  fuerte  
    llueveAux = 1; 
  }

  if (valorLluvia > 900){
    Serial.println("Lluvia Nivel: NO LLUEVE");
    nivelLluvia = "NO LLUEVE ";
    nivelLluvia.concat(valorLluvia);
    llueveAux = 1; //OJO TIENE QUE ESTAR EN CERO---------------
  }
}

Readings of the night

05:37 - 1023
08:07 - 112
08:21 - 75
08:37 - 142
09:32 - 264
11:44 - 853

2

The only way to stop dew forming is by heating it above the dew point which varies depending on the relative humidity. Perhaps aim for 25 dec C and see how it performs.

In terms of heaters, perhaps look at the USB dummy load devices. 5 watts should be plenty providing that the sensor is sheltered from the wind.

3

But the idea is not to heat the sensor.
I was thinking about taking the value of rain as 0. Because I was looking and it never reaches this value with dew. Anyway, it does not convince me

4

Buy a second sensor ($1 on Ebay) and place it close to the first sensor. Put a cover over the top of the second sensor so that it is protected from the rain. Allow an air gap of at least 3cm above the sensor so that air can circulate and dew can form just like on the first sensor.

If both sensors give a low value you have dew.
If the exposed sensor gives a significantly lower value than the protected sensor then it indicates rain.