Arduino Projects, 1: Sous-Vide Cooking (UPDATE)

With an Arduino Duemilanove on the way, TAE is considering what his first few projects should be. Back at the beginning of the year, I mentioned that I'd like to experiment with sous-vide cooking. Unfortunately it turns out that the cheapest "at-home" sous-vide cooker is $449, which is ridiculous. This New York Times article details the Sous-Vide Supreme, and suggests that a DIY sous-vide system would cost in the neighborhood of $1,500 to make on your own. The article then goes on to suggest that the SousVideMagic device, a PID controller to maintain water temperature, costs $139. All other supplies must be bought separately.

TAE scoffs. A pot of warm water should not cost $1,500. A PID controller should cost pennies. In fact there should be absolutely no reason why the entire Sous Vide cooker should cost more than about 50-60 bucks.

With that in mind, TAE's first project will be an Arduino Sous-Vide Cooker. For this project, I'll list the prices of every part I need, however for me most of these parts are free, due to the unique nature of the work I do (rapid prototyping, most mechanical and electrical parts I need are laying around in the labs).

Parts:
Cooler or some other large container: Free
Arduino Duemilanove: $30
NTC submersible Thermistor (0-100 celsius): $4
10k resistor: $0.03
Submersible Heating Element: $9.60
Relay: $3.75
Water Circulator: $9.99
"Done" Buzzer: 1.67
PID Control code: Free
Thermistor Analysis Code: Free

Total Cost: $59.04

The thermistor provides temperature readings of the water bath. The resistor acts as a voltage divider so the thermistor works. This is fed directly into the analog input of the Arduino board. The Arduino then reads that into the PID control and, if necessary, kicks on the heating element for X seconds. The program then waits Y seconds to take another temperature reading...and repeat. The PID control loop allows me to easily set the temperature I want to maintain, as well as a minimum run-time. At the end of the run-time, the program fires off the "Done" buzzer, alerting me that the food is now USDA safe, although I can cook it longer if I want, as the loop doesn't terminate until I do so manually.

Now, for me personally, this will cost almost nothing. I have the resistor, relay, cooler, Arduino board, water heating element, water circulator, and software, so all I need is the thermistor and done buzzer, total cost $5.67 .

Yes, for less than 6 bucks I can build a $450 dollar device. Updates to come.

Update: This project is COMPLETE. Please see this post for the follow up. Final cost was 32.32 for a fully functioning sous vide cooker.

Update 2: Schematic can be found here.
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