Side-Projects

Sous Vide Arduino

After moving to NYC, we acquired an egg eating habit. While I scramble them most of the time, at some point we were starting to make soft boiled eggs daily when we managed to get our hands on some dark soy sauce.

Daily inconsistencies in quality didn’t go away much even after removing variables such as egg temperature by placing eggs on the counter, standardizing the amount of boiled water and the time spent in the water. Somehow the eggs would be over or under.. and also due to the initial high temperature, the outside whites would also be set while the inside whites hadn’t. When we did 4 eggs instead of 2, there was an even greater variation in outcome.

Obviously the thing most suited for the job is a sous vide machine and having built one in Jan 2014 with a proper PID controller, I wasn’t keen on building another until I realised how few parts I required from the plans here and the code here. I already had 2 arduino UNOs on loan and the rest of the parts would be cheap as chips considering I already had the rice cooker. I would just strip out everything unecessary including the display, the buttons and hard-code it just to make eggs at 60°C.

I had to stuff it into a small box that used to shelter pineapple tarts as I had nothing else.

IMG_20160408_005815

IMG_20160408_005729

Notes:

  1. I particularly like how he did not implement a PID algorithm as they are really difficult to tune but rather wrote the code to operate the heating element according to how a human would operate it by switching the power on and off while doing some simple calculations about how fast the temperature was rising and falling. The setup really nailed the temperature in my tests and measurements with a Thermopen.
  2. Changed Piezo Pin from pin 13 to pin 7  so I could use pin 13/onboard LED as a status indicator
  3. Added a Status Indicator on PIN13. Flashes onboard LED to let user know what state the Arduino is currenty in
  4. Flipped RELAY_OUT_PIN from active HIGH to LOW for an active low relay I purchased. I think the original creator had a relay which activated when the voltage was high
  5. Hardcoded temperature to 60 deg celcius
  6. Aliexpress is crazy crazy cheap

Next improvement will be to control it from Home Assistant hosted on a raspberry pi so I can set it to make eggs remotely and switch it on when the time is right. I’m going to be using ESP8266s communicating over MQTT. The parts are slowly making their way from China.. 🙂

Standard

Leave a Reply

Your email address will not be published. Required fields are marked *