The idea is equivalent substitution. The data of the topic is indeed some problems, according to the current of the alarm can be calculated, even if the sliding rheostat is adjusted to the maximum, when the thermistor resistance value is 800 ohm, the alarm has begun to alarm. The requirement of the question is less than 650 euros before the alarm. So the data Settings are not very good. But the question can be done, it won't have much impact.