Load the completed sketch for Project 22 from your Arduino sketchbook and download it to the board (see Chapter 1)
The completed project is shown in Figure 8-4. To test the project, turn the rotary encoder, setting the set temperature to slightly above the actual ing temperature. The LED should be on. Then put your finger onto the thermistor to warm it up. If all is well, then when the sei temperature is exceeded the LED should turn off and you will hear the relay click. You can also test the operation of the relay by connecting a multimeter in continuity test(beep) mode to the switched output leads. I cannot stress enough that if you intend to use ges your relay to switch mains electricity, first put this project onto a properly soldered Protoshield. Second, be very careful and check and double- check what you are doing. Mains electricity kills. You must only test the relay with low voltage unless you are going to make a proper soldered the project from this design.