Picture of Universal controller for sous vide cooking
A while ago we built a $50 dollar sous vide machine to start messing around with sous vide cooking.  We loved it, and it has been precise and stable over a long period of time.

However, we thought it'd be awesome to create a brain that could control anything based on the thermocouple output. Something that would work with a rice cooker, bucket heater, or even a smoker. We could've gone out and bought a $160 Sous Vide Magic, but we built our own controller for $70! And now we'll show you how to DIY.

Again we've avoided soldering anything, which simplifies the construction considerably.

You can check out some recipes and more DIY sous vide advice at our blog. The details in this instructible are posted there as well.

Warning: do not embark on this if you are not comfortable with electronics, including high voltages. AC power direct from the wall goes through some connections, which can lead to personal injury or death.

Parts: Hardware supply:
  • 2 foot air conditioner extension cord
  • 2 foot 12 gauge wire
  • 1 foot double stranded 18 gauge wire
  • Scissors
  • Electrical tape
  • Duct tape

come on man... a large pvc box is like 8 bucks . im an electrician. if this is in canada i know its a CEC nightmare. if isnt im still quite sure its against code ... this is not how to do this.

mrkrog2 years ago
Here’s a hint for anyone shopping for parts. Lowe’s sells a cheap 6 outlet power strip. My local store sells it for a bit under $3.50. If you take it apart, you get a 3 foot grounded power cord with 14 gauge wire that can easily handle 15 amps. As a bonus, it also includes a lighted switch that also functions as a circuit breaker.

For a little more money, you can get a 5 or 8 foot version. If you cut off some of the cord and strip off the outer insulation, you get some very good wire you can use for connecting your components. (I bought the 5 foot version and didn’t have quite enough wire for my rig. You may want the 8 foot version if you take this route.)
mrkrog2 years ago
I just finished building a sous vide controller using a JLD612, a PT100, and a rice cooker. As soon as the probe went into the water, the temperature reading started jumping all over the place. I soon figured out that it would go crazy any time the probe contacted a grounded appliance. (My non-grounded crock pot, for example, didn’t cause any trouble.)

Some PT100s have a metal braid around the cable. If you have one like this, you should add a wire that connects the braid to one of the non-red (usually blue, yellow, or black) wires coming from the PT100. (All 3 PT100 wires still need to be connected to the temperature controller.)

My PT100 is a cheap unshielded version. (No metal braid around the cable.) So, I solved the problem by connecting a non-red PT100 wire both to ground (the green wire in the power cord) and the temperature controller. Now the temperature reading is perfectly stable.

I hope this information helps somebody.
devineDIY4 years ago
That is a wee bit dangerous leaving the AC exposed like that, no?

Ouch!? :c}
abefetterman (author)  devineDIY4 years ago
We have insulating tape over everything, so nothing is exposed per se. But my roommate was not happy with the prospect of running this contraption without supervision.
In my experience, I found that rubber hose, sealed with rubber cement or hot glue, makes an excellent insulator for wiring. I used some from an auto parts store that is used to replace broken fuel lines. 1: It keeps everything neat and tidy, and 2: as long as the spots where wires are coming out of the hose are sealed properly, it is extremely water-resistant (and durable). This tip should reduce the possibility of accidents involving exposed wire.
Belana3 years ago
No way!! , great!! Do you think I could use it in my small table top glass fusing kiln?
mosman3 years ago
Hi Guys,

Thanks for this great instructable. We made this a couple of weeks ago and have been having a great time sous vide'in ever since.

However, we have run into one issue. We purchased the bucket heater you recommended above. We needed it as we are practising for a 150-200 steak dinner. When we plug the heater into our controller we get a 3-4 degree temperature swing on the PID. The heat maintains (even over 48 hours) but the display bounces 2 degrees up, 3 degrees down, 1 degree up, 2 degrees down, etc.

We also bought the coffee urn you recommend on your site and have no problems with PID reading there. It is directly related to the heater. Have you experienced this? Any ideas on how to remedy the situation?


Mindmapper13 years ago
I like your idea and for me it is a good starting point. However as with other comments the construction shown is electrically very dangerous. Water and electricity do not make for a good combination. I agree with your room mate about not running this without supervision and then the other part of me says don't be anywhere near it while it is on. Electrical connections twisted and taped are NOT SAFE on mains voltages. All connections should be secured with solder or better still through terminal blocks. Might be sensible to fit an RCD trip on the plug.

Bucket heaters are not designed for food use so personally I would not use one.
dgingrass3 years ago
Any suggestions if the pt100 thermocouple has one red and two blue connectors??
abefetterman (author)  dgingrass3 years ago
I would try the two blue on 8 and 9, with the red on 10. You may need to switch around the 8 and 9 blue wires for higher accuracy.
rszabo13 years ago
I'm basically making my own PID controller from scratch. I'm still not sure exactly how to tune it but I'm thinking that I can this with a very similar SSR and a different thermocouple. Any advice?
Great instructable, I have been working on getting one of these going this weekend. I bought the same SSR you used - bought two of them actually - and can't get either of them to work with the controller. I even tried plugging the DC into an old laptop charger I have that outputs 19v DC... Still nothing. Does the LED on your SSR turn green when it is functioning?
abefetterman (author)  MikeQueenCreek4 years ago
On mine the LED turns red when the power is switched. Try switching the polarity (the wires going to 3 and 4), and check that the voltage you apply is within the range marked near "input" (mine is 3-32 V). You may check that you are really getting a voltage across the terminals using a multimeter.

If your multimeter results are ambiguous, I would get a fresh 9 V battery and a 9V battery header, and attach the two outputs to 3 and 4 (black to 4, red to 3). If that doesn't light up the LED, the SSR is broken.

Good luck!