No hands - see the water temperature directly with the naked eye

Now the temperature control element has done so good, through the temperature sensor element to convert the heat of the water temperature into light energy, show it to people to see (with bright colors to distinguish the temperature of water), because of the distant understanding of a little electronic, it is so guessed: In fact, this function should be very simple to achieve, through our daily electronic products often used in the temperature sensor - thermistor can do, but we did not think of such a good idea, through the size of the resistance to control the output voltage, by voltage or other parameters to determine what color LED bright