Wifi Humidor Ingredients

This is a list of parts that I used to create my prototype. I will try my best to remember where I purchased each part and will add a link where applicable.

Parts:

• Raspberry Pi B
• 8 GB SD Card
• 5V Power Supply
• 9V Power Supply
• Wi-Pi USB Wi-Fi Adapter
• Breadboard
• C5478 Transistor
• F/F Jumper Wires
• Test Leads with Alligator Clips
• Flat Ribbon Cable (28 AWG or thinner) 
• 5 Pin Molex (SKT)
• 5 Pin Molex (HDR)
• DHT11 Temperature/Humidity Sensor
• Small CPU Fan
• Small Plastic Container
• 6 Small Bolts
• 10 Corresponding Small Nuts

Tools:

• Drill
• Wire Cutters/Strippers
• Soldering Iron
• Solder

DISCLAIMER: I am not an electrical engineer. Most of the stuff I cobbled together with a wish and a prayer. Please proceed with caution and at your own risk. And don't make fun of my crappy soldering.

The most important feature I wanted was a system that would try and maintain a set humidity level. That means if the humidity drops below a specific value it should start adding moisture until the specified level is reached and then turn off... and rinse, wash and repeat.

To achieve this a reservoir for distilled water was needed. I used a small plastic container I found at Walmart. This particular container had a plastic lid. The plastic lid worked out nicely because it made it easy to refill water and also easy to attach the necessary hardware. Another thing I thought of was to use some florist foam to keep the water from evaporating too quickly but I figured I could add that later. I really just wanted to get things going and tweak as needed.

Small plastic container.

The next thing I needed to make this "active" was to add a fan so that it could push moisture out of the container. Because the lid was plastic it was easy to drill some holes through it. Some holes were for ventilation and 4 holes were for the hardware to mount the fan. I "eye-balled" most of it so in the picture you'll see that I ended up using only 3 bolts. I chose to put the fan on the inside and oriented the fan so that it would "push" moisture out.

Small DC fan mounted on underside of the lid.

To measure the humidity I mounted the DHT11 sensor on top of the lid using two bolts through 2 holes that I drilled. I placed it as far from the fan as I could. I actually used a couple of bolts between the board and the lid as well to give it some height.

DHT11 sensor mounted on top of the plastic lid.

The other feature that I wanted was the ability to monitor what was going on in my humidor remotely. To achieve this I figured I needed some kind of web service that I could use in conjunction with either some web-based user interface and/or native phone application. Here is a list of things I wanted to be able to do remotely:

• see current humidity inside the humidor without opening it
• see current temperature inside the humidor without opening it
• see historical temperature and humidity data over time in some nice graphical way
• see if the fan was currently running
• see historical fan data - like duty cycle or something
• set the humidity level that I'd like to be maintained
• get notified when the water is low or needs refilling
• keep track of the inventory inside the humidor
• keep track of tasting notes for particular cigars
• share inventory and tasting notes with friends

This is the interface that I came up with. It's still a work in progress but has most of the stuff that I wanted. This was built using a Java REST web service running in Tomcat. The UI was written using GWT. The data shown in the charts is only for an hour or so. I started everything from scratch in order to take a screenshot.

In the next post I'll go over the setup of the Raspberry Pi and the wiring of all the components since that should be all setup before going through the software side of things.