Ever wondered how your Air Conditioner or Heater or Refrigerator adjusts its temperature automatically? The answer is A Temperature Control System. This article will show you how to build a model of such temperature control system using minimum components and without any complex circuit. First, let us learn few terms. Control System is a combination of various physical elements connected in such a manner so as to regulate/direct/command itself or some other device/system. Feedback is a fractional part of the past/present output which is fed back to the input. In case of positive feedback, it is added to the input and if it is negative feedback then it is subtracted from the input. Depending on feedback it is divided into two types:-Open Loop Control System(Feedback is not present), Closed Loop Control System(Feedback is present). Keep on reading to find out what the system consists of and how it is made.