Sous-vide cooking is a great new way of cooking food. I will not explain why and how it works here... for great recipes and explanations, you can check out those guys :
Unfortunately, a good (and I mean precise to the half °C) sous-vide machine is very very expensive (500, 1000$ or more). If you wonder why you need such precision, I suggest you check this out :
Some Arduino-based designs come cheap (50, 60$), but as they are based on PID regulation , they require adequate tuning to perform well. Good PID tuning is very hard to achieve in practice, so those designs don't hold well against reality (at least, in my experience). Also, who needs a 20$+ LCD screen when a cheap 5$ led 8-digits display does a better job in terms of readability.
After weeks of work and tests, I came up with my own design, with the primary goal of useability in mind. Behold the "Adaptative regulation sous-vide cooker"
automatic cut-off after 24 hours of operation
automatic cut-off when temperature reaches 95 °C
allows target temperature only in the safe 50°c to 90°C range
Parts needed :
You'll be set for approx 40$, maybe even less. That's not counting the rice cooker.
Since you'll be having a rice cooker full of water when in operation, you'd better protect the high voltage part of the circuit against spills.
I choose to put the relay under a transparent plastic box and to seal the whole thing with silicon.
Wiring is pretty easy :
Pushbutton 1 :
Pushbutton 2 :
Temperature sensor :
Outputs :Piezo buzzer :
8-digit LED display :
The Arduino code for this project can be found here :
Upload and enjoy!
Note : you will need the following libraries installed in your Arduino Environment to be able to compile the project :
To install a library in your environment, follow this guide here : http://arduino.cc/en/Guide/Libraries
You'll want to pull away your food from the bottom of the rice cooker so that it is heated by the ambient liquid, not by the heater itself. To do that, I used some stainless steel frame pulled out some cooking utensils.
Voilà. Enjoy ... et bon appétit!
Use the 2 pushbuttons to set the target temperature (acceptable temperatures are within the 50°C to 90°C range).
The actual temperature can be monitored on the led display.
It is advisable not to open the lid during the initial heating phase, where the characteristics of the rice cooker are monitored.
When the buzzer sounds, you can open the lid and put your bagged food in the water.
If you connect the Arduino to your PC, data is sent to the serial port. Once stripped, this data can be used to plot the temperature over time.