Curing Chamber Development

[TrickyDick]

That is basically my setup, a 4.5 cu. ft. refrigerator converted.

 

Except mine is also an indoor smoker, using an external cold smoke generator. Heat for smoking is actually a 500 watt halogen bulb dimmed to 300 watts. It can get temperature to 200F for smoking. Any higher may melt the plastic interior.

 

Moisture is added using an ultrasonic humidifier.

 

dcarch

How do you have your bulb mounted inside the fridge unit?  Do you have any shielding material between the bulb and the plastic?  You are using only a single lamp/bulb? is the temperature uniform enough throughout the fridge or do you require a fan .  I would suspect a halogen bulb creates significant radiant heat such that the closer to the source, the higher the temp and vice-versa.  For fermented sausage making, I would only need temps up to 105 for fast fermented sausage, but mostly I'll be wanting slow fermented (90 degrees and below).  I'm going to use a dimmer on a single 500 watt Halogen lamp and see what I can get.  I suppose if I ever want to actually COOK in the chamber, the halogen bulb might be able to achieve that too if it can get up to 200 degrees inside the fridge as you say.

 

Thanks!

 

TD

[TrickyDick]

Another question for Chris H,  the top mounted exhaust/dehumidification fan....  Is this powered by the Arduino directly from its output pin or via another power source?

 

Thanks

 

TD

[Chris Hennes]

I use a small transistor to switch the power to the fan from the Arduino's 5V supply. The digital pins can't supply enough current.

[TrickyDick]

Ahh,  I think that you had previously mentioned that now that I recall.

 

By the way, are you using any of the internal pull-down resistors on any pins, or using any external pull-down resistors?

 

Should have the last few components I need by the weekend to do some more testing.

 

TD

[Chris Hennes]

I'm not doing any sensing that would require a pull-up or pull-down resistor since I'm just using the DHT22.

[TrickyDick]

Struggling getting the LCD connected to the arduino. Looking at the code, and been reading the Simon Monk book beginning with sketches. I don't think I have the knowledge to convert to using i2c for the LCD, so I picked up a plain one. But it didn't have header pins. So a got a header pin rail, but the spacing was off! GRR! Working on getting it fired up. I found a diagram of how to connect the LCD to the arduino with a Google search here: http://vanceance.blogspot.com/2013/04/hd44780-16-x-2-lcd-with-arduino.html

I'm going to try that out as soon as I can get either a header pin rail that fits or just get a LCD with those already included.

By the way, in your code, I never see pin 8 specified as input.

Do you need to specify using pinmode command that the pin 8 is an input pin, or does that happen in one of the libraries and I can't see it in the main sketch?

Thanks for the help.

By the way, have you tasted any cured meat from your chamber yet??

TD

[Chris Hennes]

I don't have the code in front of me right now, but my recollection is that's the pin I used for the DHT22, which is set up in the call that initializes that object.

[TrickyDick]

Thanks Chris!

 

Well, I think a big issue I was having was inappropriately wiring the LCD.  Now that I've got that corrected, I am getting information on my test setup.

I've wired my breadboard with LEDs acting as surrogates for the 4 controlled devices.

I think in my testing, that I've fried the Sensor however.  I have been getting sensor data error. 

I am thinking to replace it, as I think I now have my wiring all correct. 

It's giving me 0ºC, 0%RH on the readout, and there is no change when I fiddle.  I think I might have inadvertently fried the sensor somehow.

At least the LCD working is forward progress on my part and proof that I've got the code successfully uploaded.

 

By the way, I had asked Chris about pull down resistors and he said that he wasn't using these.   For the sensor input, I saw this website (https://learn.adafruit.com/dht/connecting-to-a-dhtxx-sensor) where they use a pull UP resistor. Are you using this wiring pattern Chris?

 

As far as the coding, I am really not much of a programmer.  I tried to decipher the code, but for me, without significant amount of time and energy to learn the stuff, I'm like a level 1 programmer trying to interpret something beyond my capabilities.  I did go through the library files and the code over at Github, but I still don't see the initilization for the input pin.   I think that the DEFINE_DHT PIN (or something like that) passes the value of the input pin number to the library (DHT) wherein, the pin is initialized as an input. 

 

Anyways,  I'm plugging away.  When I get a new sensor, I'll be back!

 

TD

[Chris Hennes]

I actually had to go out and look at the setup, I couldn't remember off the top of my head. Yes, sure enough, I've got a 10K pull-up resistor on that data line from the sensor. Sorry to lead you astray there. 

[TrickyDick]

Ok thanks! I'll be sure to wire that into my setup. New sensor here on Thursday. I'll post an update when I can. By the way, thanks for the code sharing. I'd not have been able to do it otherwise.

[TrickyDick]

Still not working right with new sensor. I've triple checked my wiring.  Cold be a bad breadboard, bad interconnect wires, or who knows what.

The sketch is uploaded.  Sometimes when I turn it on, I'll get a message BAD SENSOR DATA, other times It'll just display:

CURRENT TEMP 0ºC RH0%

No averages ready yet

 or something similar to that.

 

Strange.

I might take the 20 hour online arduino course for $50 and see if I'm just being boneheaded...

 

TD

[Chris Hennes]

Make sure you've plugged your sensor into the same inputs that I did, or change the code to match.

[TrickyDick]

Thanks. I have four pins on the sensor. From left to right connections are: 5 vdc, pin 8 plus 5vdc with 10kohm series resistor pull-up, nothing, ground.

[Martin Fisher]

Do you still have this up and running Chris?

How is the DHT22 temperature/humidity sensor holding up?

[Chris Hennes]

Yep, still running (though it's actually between cures right now). I haven't had any problems with any of the setup. I still haven't bothered making a real circuit, it's still living on the breadboard as in the original photo. I did add a humidifier, but haven't yet added a heat lamp (though I will for my next cure, I think). Then I need to tweak the code to have an incubation stage.

[Chris Hennes]

I decided to implement the incubation stage manually, rather than having it run automatically for some set amount of time and then switch over to the long-time cure. I'd have had to add an input switch to the system, and I'd run the risk of accidentally triggering it, so instead I've just got two versions of the code and I manually upload the one I want to run when I need it. This is a safer way, I think.

 

I am now using a seed-starting heat mat instead of a heat lamp: it's much slower to respond, but they are designed for wet environments and are easy to clean/disinfect. The humidifier is just a cheap misting variety. Here's what the temp and humidity looked like during last night's incubation phase trial run:

 

 

The humidity cycles a LOT, basically because the humidifier is much too powerful for such a small enclosure and can't really be run at a lower power (it's just on or off). I don't think this will be a huge issue, but I'm going to start up a test-cure today so I guess we'll see.

[KennethT]

What happened at around 45000 sec?  Was that a door open event?

[Chris Hennes]

The curing chamber is in my garage: that was a garage-door opening event.

[Chris Hennes]

Let the games begin... current targets are set to 27°C and 80%RH for the incubation stage, which I will run overnight. Salume suggests only a 12 hour incubation stage, which is much shorter than the recommendation from Chr. Hansen (the bacteria's manufacturer). However, I've had superb results from this book so far so I'm going to go with the book's recommendations, I think. There's no real rush to get the pH all the way down to the target right away, the recipe includes plenty of DQ #2.

 

 

 

[Chris Hennes]

The incubation phase went smoothly, with the average hitting the target temperature of 27°C exactly, and only a little bit over the humidity target of 80%. Everything smells right, so this morning I kicked it into the long-term curing program, with a target temperature of 15°C and 60% RH. Here's the data from the incubation:

[dcarch]

"---- The humidity cycles a LOT, basically because the humidifier is much too powerful for such a small enclosure and can't really be run at a lower power (it's just on or off).  ----"

 

Try using Peltier junction solid state device. It can either heat or cool by reversing polarity.

 

Cheap on eBay.

 

dcarch 

 

 

[Chris Hennes]

I don't follow, @dcarch -- I've never heard of a Peltier humidifier, and I don't need any additional heating or cooling. I found the cooling performance of Peltier devices to be insufficient at this price point compared to a compressor-driven refrigerator, which is how I wound up with this system in the first place. Got a link to a Peltier-based humidification system? 

[dcarch]

8 minutes ago, Chris Hennes said:

I don't follow, @dcarch -- I've never heard of a Peltier humidifier, and I don't need any additional heating or cooling. I found the cooling performance of Peltier devices to be insufficient at this price point compared to a compressor-driven refrigerator, which is how I wound up with this system in the first place. Got a link to a Peltier-based humidification system? 

 

A humidifier works on refrigeration, and a Peltier junction device is a solid state peltier thermoelectric refrigeration device with no moving parts. Water vapor will freeze on the surface of the device. Reverse the polarity and the ice will melt and drain away. You can get a solid state ultra sonic generator for less than $10.00 to generate humidity and a Peltier device to dehumidify.

Here is one I made for my smoker:

 

You can buy a Peltier chip for less than $1.00. You do need a DC power supply to power it. 

 

dcarch

 

 

[Chris Hennes]

I'm in Oklahoma: dehumidification is not a problem, I just use a fan (right now ambient humidity in my garage is 26%). I considered a smaller humidifier but decided to just stick with what I already owned as a start. If it ends up needing to run often during this cure I'll revisit the data and see if it's necessary to downsize. 

[Martin Fisher]

Do you still have this running, @Chris Hennes?