It runs on mains power and uses a 100dB piezo buzzer for ear-splitting effectiveness to alert [Adam] whenever the freezer is at 32°F/0°C or above. If the Arduino loses sight of the DHT22 ...

Arduino is a great way for today’s novices to start to learn how to write and run codes that interact with the external world. Somebody on Facebook recently asked about finding an easy-to-use shield .