{"id":1012,"date":"2017-09-05T21:11:24","date_gmt":"2017-09-06T03:11:24","guid":{"rendered":"https:\/\/supermediocre.org\/?page_id=1012"},"modified":"2025-12-13T16:06:42","modified_gmt":"2025-12-13T23:06:42","slug":"humidor-controller","status":"publish","type":"page","link":"https:\/\/supermediocre.org\/index.php\/rich\/richs-projects\/electronics\/humidor-controller\/","title":{"rendered":"1st Gen Humidor Controller (2018)"},"content":{"rendered":"

The Idea<\/h1>\n

Recently, my bud Vic mentioned that he was having trouble controlling the humidity in his cigar humidor. He had an electric fan over a bowl of water to circulate humidity, but he would have to remember to turn it on or off. Forgetting to turn off the fan meant soggy cigars (perhaps an exaggeration).<\/p>\n

So I opened my big yapper and said it would be trivial to automate the fan control. Well, it wasn’t exactly trivial, but was a rather straightforward Arduino design. Nevertheless, perhaps the resulting design will help others.<\/p>\n

The Design<\/h1>\n

Vic’s got a bad-ass humidor. It’s got two separate levels and holds many hundred cigars. So we decided it would be best to control the humidity separately in the two levels.<\/p>\n

I had on hand a DHT22 humidity\/temperature sensor, and most of the required parts. So I downloaded the Adafruit sensor libraries here <\/a>and here<\/a>. The second library is specific to the DHT22, but the first library is required too.<\/p>\n

Within a few minutes, I had the sensor hooked up and was reading data from it. Easy.<\/p>\n

I wanted the unit to be compact, so I chose this <\/a>small OLED display. These are cheap and look great. They use a I2C interface, so easily connect to the Arduino.<\/p>\n

I drive the fans with a couple of\u00a050n06 MOSFETs; overkill for this low-current application, but I had them on hand.<\/p>\n

The rest is pretty straightfoward. I put it in a little clear Hammond box (part number\u00a01591CTCL) that I got from Digikey. I love these little boxes – I like to see the guts of the project and don’t need to cut a hole for the display.<\/p>\n

The Schematic<\/h1>\n

The schematic is a bit scrappy, but it gets the idea across.
\n\"\"<\/a><\/p>\n

And here is the Eagle file:\u00a0humidor_controller<\/a><\/p>\n

The Code<\/h1>\n

Here is the source code, in Arduino archive format (zipped too).<\/p>\n

humidor_controller-170905a<\/a><\/p>\n

A Few More Pictures<\/h1>\n

Note that it was hard to get a good photo of the OLED display because it is constantly scanning, so aliasing showed up on the rolling-readout camera. The last photo was taken with a long integration time which helped. The display actually looks remarkably crisp in real life!<\/p>\n