mandag den 23. februar 2015

Arduino controlled meat curing chamber

Hi everyone!

Well I have never made more than a few small attempts at blogging before, so this project will be my proper blog debut. About a year ago I started looking into creating a meat curing chamber for some sausage projects my father and I were planning. I ended up building an Arduino based controller, for an old fridge, allowing me to control the temperature and humidity. My first build of the hardware was very much an on the fly design, meaning that I ended up with a lot of semi loose wires going to and from different components and a breadboard. Therefore I have decided to rebuild the entire thing. In this review it will be built inside a cabinet, with the intention of keeping everything neat and tidy.



Some pictures of the not so neat and tidy first build.


So this blog will be a documentation of the building process, taking you though the different steps.

When the project first started, I quickly decided that combining an Arduino with an old refrigerator would be the way to go. So I started surfing the interweb for someone doing a similar project, but I couldn’t find anyone who was. Taking the imaginations and diversity of people doing Arduino projects all over the world, this surprised me quite a bit. After some time, though, I found Franz Evert’s project over at MeatGeek, where he and a friend had started building a controller unit for a curing fridge. But as far as I know they haven’t finished the software part of it. I have chatted a bit with Franz discussing back and forth, on how he and his friend are approaching their project, and I have stolen a few ideas from them as well :)

But since I haven’t found any description of a finished project I decided to make one and give a little back to the internet.

When starting the project the first thing I did was setting up a list of requirements, which the controller had to meet.
The first two points were quite obvious;
 • Control temperature
 • Control Humidity
Then there was the nice to have’s;
 • Instant visual readout of humidity and temperature
 • Logging capability
 • The capability to change control parameters continuously

The later three are somewhere in between need to have’s and nice to have’s. I believe that in order for the finished product to be as good as possible the operator has to have the best tools at hand, in order to make informed decisions on, for example dropping or raising the humidity a few percent. Therefore it is important to be able to interact with the controller.

The list of requirements builds an easy transition to the list of components needed in order to ensure that they are met.

For the control part sensors and relays are needed. Four standard made in china 10A 250V relays were chosen. For sensing a DHT 22 sensor were bought. Together with an Arduino as a base, this should be sufficient to meet the two first requirements. For the instant visual read out, a 16x2 standard LCD display was chosen. In order to limit its demand for pins, an i2c interface was also bought.

To meet the two last requirements I have chosen to use a SD card reader. This will allow me to continuously log temperature and humidity to a .txt file. But more importantly it can also be used to store curing programs, with different settings for the controllers to use as time progresses. This is quite a neat feature if I am to say myself. Though I must admit, that it probably takes quite a while before one can set parameters for the next 30 days of curing, without evaluating them once. But I sort of like the industrial production feel that it adds to the build.

Some of the components for the build.


So these are the basic components required for the build to meet with stated demands. Off course a lot of circumferential components will be needed for connecting it all as well, but the ones mentioned here will only be the essential ones.

But I think that I have written enough for now, in order for you to get an idea of what the project will be all about. In the next blog I will present some of the experience that we have already gathered with the last build of the setup, including some graphs, and nice pictures.

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