15 comments on “Crock-Pot Yogurt Controller

  1. Awesome looking device you built there!
    How did you secure the button-board and the lcd board?
    I would have assumed it was necessary to screw them onto the top acrylic.

    • Yes, I had a hard time mounting this to the acrylic. I ended up purchasing some acrylic cement from Amazon.com and it worked moderately well. A hard press on the board will cause it to fall off, so I would recommend designing in some mounting holes. I also glued the acrylic box together. If I had a chance to do this over, I would have used screws for the box as well. Then I could have taken it apart and made modifications to the software as new ideas came along.

  2. Thank you for the reply. Ok, I guess there is no avoiding screws to secure the lcd and buttons 🙁

    I am building a similar arduino based sous vide, although using the pro micro with built-in microUSB. This way I can add a USB port to the enclosure.

    I think I need to find a way to assemble the case with screws as you suggest… Maybe something similar to the sammichSID case http://www.midibox.org/dokuwiki/doku.php?id=sammichsid

    • Sorry, I do not have any more to sell. All of the information on how to make one was posted to this site, so if you are adventurous, you should be able to make one of your own.

    • Sure, I simply soldered a Dallas 1-Wire DS1820 temperature sensor to some audio cable that I purchased from a local electronics supplier. I picked up about four feet or so of the cable, and it was flexible with a rubber sleeve over the conductors. I believe it was 1/4″ cable for microphones, or something similar. I inserted the temperature sensor, after it was soldered to the wires, into the thermowell from Brewer’s Hardware. I e-mailed them to get some help selecting the correct probe, and explained it was a TO-92 package. They responded:

      All of these items are designed for building temp sensors around to92 devices: https://www.brewershardware.com/Temperature-Probe-Ends/ They all have an ID that will fit. As far as connectors go, that’s all kind of up to you in how you’re going to get your device connected to whatever is reading it.

      Once I inserted the probe into the thermowell, I pulled some of the rubber wire insulation over the end which held the thermowell in place using friction. It works well.

  3. Just a note to say, we finally settled on a spa temp thermostat and thermostatic probe to cycle a crock pot, to control the water bath that heats the yogurt. I forget what the exact setpoint we wanted to make the yogurt, but the deadband was not more than 1.5degF. Normally spas run at 103degF, we very little deadband. I’d leave a URL of the device, but not sure the forum likes to have URLs in the posts.

    • Sounds like an interesting approach! It is probably overkill to use a PID controller, but it is fun to take pride in knowing your yogurt temperature is being controlled very accurately. I haven’t noticed much difference in the yogurt taste, but it does certainly make the creation process much easier.

  4. Great project, I’m starting in this world and I want to start by replicating this one, I have the same components (exept for the triac I have the Q6025L6) and I already checked all the connection many times, but the controller starts (in yogurth mode) the status led goes on and the crock pot starts, but after 15 seconds (aprox.) the status led goes off and also the crock pot, and thats it, the crock pot remains off alll the time….

    I don’t know what is the problem, can you please confirm me the correct connection of the DS1820 sensor, the PCB has two ports but the sensor has three outputs, I’m not sure about his connection.

    Thank you so much.

    (Greetings from Colombia)

    • It has been quite a while since I worked on this, and I can no longer recall all of the connections. However, your problem sounds like a software issue rather than a hardware issue. I’d suggest adding some code to your software to make sure it is doing what you are expecting it to do at each point in the program.

  5. How do you avoid killing the yoghurt culture when you heat to 180 degrees? Or do you add the culture in after it is heating to only 110?


    • I started with a recipe that I found online. It would be fairly easy to customize the temperature set points when you program your Arduino device. And as for whether the yoghurt culture is killed off during the heating, I don’t know. Somehow it just works!

  6. If you don’t mind checking, it’s possible that something has gone wonky with the Eagle Board file for the controller board. I’m getting crashes from Eagle 8.7.0 when trying to load it, and OSHPark also seems to think there’s something wrong.

    Looking at the schematic, it’s easy enough for anyone to start with Aaron’s Eagle files and add the buzzer, but you’ve got such a nice package here, it’s a shame to see part of it not working.

    • It is possible I was using an older version of Eagle. I no longer have this software installed, so I can’t check the file. It shouldn’t be too hard to recreate, so I would encourage you to try to design it yourself. Then you can improve it further!

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