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arduino atmega cheap crock pot diy PID sous vide

Turn your crock pot into a PID controlled sous vide cooker for $25

I’ve been wanting to try sous vide cooking for a long time, but my stove top efforts failed and I was put off by the price of a dedicated cooker.  The inner nerd in me could not justify spending $160 on a Sous Vide Magic when I knew it could be done with parts laying around my desk.

Here is the basic parts list. In addition to this, you would need a way to program the micro, a board to mount all this on, a 5V power supply, and a way to waterproof the sensor. All these parts are available at sparkfun.com

QTY    NAME              $$ $$
1        atmega328p           4.30
1        16MHz crystal       0.95
2        22pF cap                0.5
1        10k resistor           0.25
1        5k resistor             0.25
1        1k resistor             0.25
1        led                          0.25
1        16×2 lcd               12.00
1       relay                        4.00
1       diode                       0.25
2       buttons                   1.00
1        2N3904                  0.75
1        Dallas DS18B20     4.25
TOTAL                             24.75

This parts list does not include a power supply(5V) or a board to mount all that on, but I figure anyone that wants to take this project on has extra wall warts, and likely a bread board or some protoboard.

To waterproof my sensor I used some adhesive lined heatshrink tube I found on amazon http://www.amazon.com/gp/product/B0013HSQXW/ref=oss_product.

To use the controller you can either slice one line of your crock pot’s cord and stick the relay inline with it, or get a short extension cord and do the same. Using the extension cord doesn’t damage your crock pot, and allows you to move the controller to another crock pot… or whatever else you want to control. I set my crock pot on low and just plug the controller in. This could depend on your controller, so you may need to use a different setting.  With the PID control, once my temps settled, I never saw them vary more than +/-.5F.

Here are the results of the first time I used it. It was a roast I picked up at Costco that was cooked at 133F for 8 hours. Mmmmm



Eagle schematic and board layout are available on github

UPDATE: I had some boards spun up, still waiting on testing them, but here is the source.