const uint8_t pinVT = A0;
const uint8_t pinVD = 13;
const uint8_t sensor = 3;
uint16_t valVT_this = 0;
uint16_t valVT_prev = 0;
int16_t valVD = 0;
void setup() {
  pinMode(pinVT, INPUT);
  pinMode(pinVD, OUTPUT);
}

void loop() {
  valVT_this = analogRead(pinVT);
  if(min(valVT_this, valVT_prev)+sensor < max(valVT_this, valVT_prev))
  {valVD = 500;}

  else if (valVD>0){
    valVD--;
  }
  valVT_prev = valVT_this;
  if(valVD > 0) digitalWrite(pinVD, HIGH);
  else digitalWrite(pinVD, LOW);
}