The electronic temperature controller by the conversion display mechanism, setting mechanism, operation mechanism, an output mechanism compared to four institutions. When the temperature sensor to the temperature field is converted into an electrical signal (or mV) is transmitted to the temperature controller, temperature controller display mechanism to convert electrical signal into a digital display indicating or simulation, and in the internal design and setting mechanism setting were compared by comparing the organization (or PID operation) through the output mechanism of output to the controller (solid state relay, contactor, power controller), then the controller control of heater / cooler for.