So it's apple season here in the Northeast of the U.S. I read that the best environment for storing apples at is in a cool (~35°F / 2 °C) location with high humidity ~ 90%. Well, the refrigerator has the temperature, but how do I measure it and the humidity? My Moteino-based temperature and humidity module could do it. But wait, isn't the metal box of a refrigerator essentially Faraday Cage?
With some skepticism, I put the Moteino transmitter module in the fridge and impressively, it gave me solid temperature and humidity readings from the inside the refrigerator to a MoteinoMEGA receiver on another floor of the house. The receiver retransmits the readings back down to a Moteino display unit outside the refrigerator. The temperature was in the right range, but the humidity was low - below 30%. I put a dish of water and a sponge along with the apples and the Moteino in the refrigerator crisper and the humidity has gone up to 90%+. If these conditions hold, maybe the mighty Moteino will provide me with fresh apples well into the winter! :)
While a refrigerator isn't the ideal place to place a transmitter, it's not a very good Faraday cage either. There are lots of gaps such as the door seals which are made of non-metallic material and the metal of the doors are often not electrically connected to the rest of the cabinet. When you are trying to contain RF it is actually quite tricky, it will find all kinds of little gaps to escape.
Quote from: DonpK on November 15, 2019, 08:03:30 PM
With some skepticism, I put the Moteino transmitter module in the fridge and impressively, it gave me solid temperature and humidity readings from the inside the refrigerator to a MoteinoMEGA receiver on another floor of the house.
Try that with an ESP8266 or 2.4ghz based transmitter ;)