Hi guys, I am in trouble with a (seemingly "simple") problem with a linefollow sensor 
. The sensor gives a HIGH value at his output when white has been detected, and it gives us a LOW value when black has been detected, now that part works pretty fine (sensor is all alright). Now I want to use the sensor for steering a relais, yes I used a transistor for it, so I want to make the relais HIGH when black gets detected, BUT, it should stay HIGH even when the sensor detects white again, it can only change when the sensor detects black again. So did I make this clear to you guys? It's actually just like a start stop function, but with a linefollow sensor. I just don't get it.. Even tho I maked a start stop like a million times before when I worked with heavy current.
As it seems to be normal on this forum to add the code you already have, I've done that for you to:
const int linePin2=52; //Connects the output pin from the linefollow sensor to Arduino pin 52
const int relaisPin=53; //Connects Arduino pin 53 to the basis of the transisor who steers the relais
int lineValue2=0;
void setup() {
pinMode(linePin2, INPUT);
pinMode(relaisPin, OUTPUT); // This pin is not directly connected to the relais but to a transistor first
}
void loop() {
lineValue2= digitalRead(linePin2);
if (lineValue2 == LOW) {
digitalWrite(relaisPin, HIGH);
}
else {
digitalWrite(relaisPin, LOW);
}
}
As you guys may have noticed I used "const int" as command, I did that because I saw something similar on the Arduino site: http://www.arduino.cc/en/Tutorial/Button
I thought that it was just the same as mine but instead of using a button, using a linefollow sensor.
So now the actual problem for me is that the relais is losing his HIGH state when the sensor detects white again.. Something that shouldn't happen. It should stay high till the sensor detects black again.
I really hope you guys can help me out with this one.
Thanks