Project LCD Thermostat The temperature must be regulated, as particularly susceptible to chills This project uses an LCD screen and a thermistor temperature sensor to both display the current temperature and the set temperature. It uses a rotary encoder to allow the set temperature to be changed. The rotary encoder's button also acts as an override switch. When the measured temperature is less than the set temperature, a relay is activated. Relays are old-fashioned electromagnetic components that activate a mechanical switch when a current flows through a coil of wire. They have a number of advantages. First, they can switch high currents and voltages, making them suitable for controlling mains equipment. They also electrically isolate the control side (the coil) from the switching side so that the high and low voltages surver meet, which is definitely.