So I'm trying to make a cooling system for my reactor that will activate whenever the temperature reaches what my sensor is set to, which is 300°C. So what I need help with is figuring out how to make the heat switch turn off when there is no signal from the heat sensor, and turn on when there is. I tried to use NOT gates but it did not work and I just got an infinite energy source. If you would like to you can include a picture in your response but you don't have to, I think I can figure it out with just words.