Temperature Switch

The LM335 is a low-cost temperature sensor with a range of –40 +100 degrees celcius. In this circuit, it is used to show whether the outside temperature is below freezing or above 20 degrees C. In the first case, you have to worry about icy roads and the outside taps freezing, while in the second case you can open the windows and switch off the heating. You can adjust the switchpoint temperatures to suit your wishes.