Bionic Banana: Pictures of how crazy I am

Discussion in 'Fridge/Freezer Builds' started by bob the noob, Feb 28, 2010.

  1. bob the noob

    bob the noob Smoke Blower

    Okay, so some of you may have read previous posts about the Bionic Banana and may have even checked out my blog. I just did some testing today and thought I'd put up a more complete picture of what it is and the parts that went into it.

    To sum up: It's a 1950's Coldspot fridge that's now an Arduino controlled 220 volt electric smoker.

    This is the Arduino "Mega" board when I put it together for testing. The thing on the upper left is the Arduino, with a proto-shield on it, with the wi-fi shield on top of that. The tester is hooked up to the 220 volt relay that controls the oven element in the fridge. You can see the temp probe near it, the end of the red pen is almost pointing at it. The software in the Arduino monitors the probe I've designated as the pit temp. If it's below the temperature I set, it puts power to the relay which then allows power to flow through the oven element. I've programmed it to shut off the element when the temperature is 5 degrees less than the set temp, to account for excess heat from the element.

    Here's my crappy label job on the side of the project case. I've got room to put maybe another 10 probes on the board, but don't have the probes currently. I'll add more as I need them. Temperatures are read on a computer on my home network, and as soon as a buddy at work gives me a hand with the PHP for my website I'll be able to monitor from anywhere and even change the temperature.

    Here's the oven element roaring away. It almost looks white hot due to the color balance on my phone's camera, but it's just the normal "red hot" that oven elements get to. The metal drawer from the fridge is above it which kinda acts as a baffle right now and grease catcher. It's far enough away so I don't need to worry about grease fires, although it may not look like it in this picture.

    Temperatures held very nicely, with the middle of the fridge and the top rack area being within a few degrees of each other.

    After letting it warm up for a while I thought I'd do some load testing. To simulate a bunch of cold meat being put in I used a foil pan full of snow/ice. Recovery time was fairly quick, it dropped to high 160s after fumbling with putting the ice in and was back up to temp within 5-10 minutes. It worked pretty good, and showed the need to possibly re-work the baffle set up. The middle of the fridge was getting 15 degrees or so hotter than the pit temp. So with a better baffle I might be able to shave a few minutes off the recovery time.

    As I think about it more though, it might be an issue of the pit probe being at the top where the somewhat cooled air is hitting it. You can see the probe at the top vs. the one hung under the pan. I guess another alternative I could do would be to put 2 or 3 pit temp probes in and program it to calculate an average between them.

    All in all it was quite a fun project. The potential for improvements is there too. I'm going to change the web interface to be more user friendly, so I can set temp alerts and timers. It'd be nice to get an email or text msg on my phone telling me that one of the pork butts is at foiling temp, or that the ribs have been on for X hours and should be pulled or sauced. I'm looking forward to doing a few more tweaks then doing a huge batch of Ribs on it. [​IMG]
  2. Wow! What a project. All you have to do now is hire a monkey to do the foiling and pulling for you.

    That is quite a crazy project, when do they hit the market?
  3. mballi3011

    mballi3011 Smoking Guru OTBS Member SMF Premier Member

    Now thats a fine job you did on your build of what looks like a mighty fine job you did with that old frig. My mother built something with an old refrig it now pours very cold beer and that was in 1954 too and it still works today.
  4. bob the noob

    bob the noob Smoke Blower

    Glad you guys like it. I'm considering writing up a full "how to" in the future. There was a lot of fiddling with the hardware/software to get it to its current state and I'm sure many here would enjoy making one for themselves.

    The base of the software came from here. I tweaked it a little to give me more temperature probes, changed it to control the electric element instead of a blower motor and status of the heating element (on or off). My buddy at work who got me started on it built one from that link for his UDS and loves it.

    The fridge itself, as I posted when I first got it, was from Craigslist. A local guy had converted it, but was using a hot plate to heat it so he could only do small batches of Jerky.

    Here's when I first got it, next to my MES which is on a stand:

    Believe it or not, I got probly 75% of the parts for it off eBay. If you use your own probes and don't need a ton of them, you could probly make one for under $100 bucks. A lot cheaper than the Digi-Q kinda thing and offers a lot of flexibility if you want to change how you use it.

    I'm hoping to figure out a way to put some sort of smoke level sensor in it to trigger a wood feed too.
  5. meateater

    meateater Smoking Guru SMF Premier Member

    Now thats slick!
  6. timleo

    timleo Smoke Blower

    I know I'd be very interested in seeing your write up.
  7. I'll jump on the "waiting for the write-up" wagon. I have a fridge project to start and I'm liking the various options everyone is doing.
  8. treegje

    treegje Master of the Pit

    Coooooooooooooool excellent job [​IMG]
  9. bob the noob

    bob the noob Smoke Blower

    I'm working on the "how to" right now, and with any luck I can have it finished in a couple days. The hard part is sorting out just what needs to be done from the software side because I hacked/slashed through a lot of code and I want to be sure I'm writing up the parts that need to be modified and where. I'm trying to write it up with step-by-step instructions so it's fairly easy to build, even if you're not familiar with hardware/software.

    The Code itself is fairly simple, and there's not a whole lot to modify. The library files and stuff that are pulled in when the code compiles is where it gets messy. [​IMG]


    The first block of code is easy to change, but the second one isn't clear as to where it needs to go in the WiServer.cpp file. I'll have to check out the working version I have at home later and use that as example.

    I'll keep you guys posted!
  10. timleo

    timleo Smoke Blower

    While I am very interested, I'm worried that the explanation of the hardware/software/programming may go over my head pretty quickly...

    Even so, I run a PID controller on my charcoal smoker that I made myself and I'm still very interested

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