- Arduino microcontroller (I use the Uno... any will do)
- thermistor, or other temperature sensor (I used this one from Sparkfun )
- 3/16" diameter aluminum or copper tube, about 6" long
- shrink tubing
- clear silicone caulk
- relay controller (this one from Sparkfun is nice, but you can make your own pretty easily)
- 9V battery or 9V power adapter
- AC oulet
- AC power cord with bare leads
- project box (I used an old cigar box)
- Crock-Pot or similar slow cooker (must have "On" setting... the dumber, the better)
- display (optional, but nice to have)
- various hookup wires
- Ziploc bags or vacuum sealer
Disclaimer: this project involves household current, which is dangerous if you don't know what you're doing. If you've never dealt with household current and don't want to mess with it, go with the Powerswitch Tail II from the Makershed or Sparkfun instead of using the relay controller and AC outlet. Please be careful, and don't hurt yourself.
Step 1: Make Your Temperature Probe
Next we're going to protect the sensor so the water bath doesn't affect our readings. Use an aluminum or copper tube (both are great thermal conductors) big enough fit your temp sensor. Seal one end of the tube with silicone caulk (or hot glue if you're impatient, but silicone would be better). When that has cured/solidified, slide the temp sensor into the tube as far as it will go, then fill the open end with more silicone/hot glue to seal it up. Use some shrink tubing at that end for good measure.
Step 2: Wire Everything Up. First the Sensor...
Step 3: ... Next the Relay Controller...
Step 4: ... Then the AC Outlet...
Again, if you don't want to mess with wiring that will be connected to household current, buy a Powertail instead. Having nicely cooked food isn't worth getting electrocuted`if you don't know what you're doing.
Step 5: ... and Finally the Display (if You Want One).
Here's how mine is connected (yours may vary):
- LCD RS pin to digital pin 12
- LCD Enable pin to digital pin 11
- LCD D4 pin to digital pin 5
- LCD D5 pin to digital pin 4
- LCD D6 pin to digital pin 3
- LCD D7 pin to digital pin 2
- LCD R/W pin to ground
- 10K resistor: ends to +5V and ground wiper to LCD VO pin (pin 3)
Step 6: Yup... It's a Lot of Wires.
Step 7: Upload the Arduino Code...
To set the cooking temperature, you'll need to modify a line near the bottom of the code... it's marked. I'll update this project in the future to let you change the temperature with some buttons or a potentiometer.
Step 8: Put It All in a Box.
Step 9: Plug It In.
Then plug your power cord into a wall outlet... if you did everything right, this will be quite uneventful.
Power up your Arduino... I would recommend plugging a 9V DC power supply into it. A battery will work too, but you'll drain it eventually, and everything will shut down in the middle of cooking.
Once you power up the Arduino, it'll greet you with "Hello, World" for a few seconds, then it will show the current temperature of your probe. Unless you're using a solid-state relay, you should hear it start clicking.
Step 10: Start Cookin!
Lastly, turn your slow cooker to "ON". You want to use a dumb, non-digital slow cooker for this project, because we're basically turning its power off and on to keep the temperature steady. A slow cooker that does a lot of thinking might have trouble booting up if we're constantly turning it off, and you'll either damage it or it won't work at all.
There are lots of resources out there for sous-vide recipes... so enjoy, and don't eat undercooked meat!