Ever since I saw the Anova tear down (as mentioned towards the end of previous post), I can’t get it out of my mind. I bet I can build that. So, as of a couple weeks ago, I started prototyping. I’m going whole hog. Got new parts, most of them anyway. I’m not pulling parts out of MK2, it is still actively used. The goal for Project Katara is $20 Anova, the whole thing, no rice cooker. And I aim to make this like a “commercial product”, you know, as far as DIY goes.
First the name, I love naming my projects. If it is not obvious, Katara is the water bender from Avatar The Last Airbender. The basics of this project is ESP-32 as the brain. Submersible water heater as the heat source. And an aquarium pump to circulate the water. A complete Sous Vide, aka the immersion circulator. The pump is key, if we don’t move the water around the heater, the water around the heating element can be boiling while the water an inch below it is still at 30ºC. Hence Katara.
Next, the prototype pic above. Since I already know the Sous Vide part, running PID on a submersible water heater based on the input from a thermal sensor, I need to test and prototype the things that are new to me. Mainly the rotary encoder and ESP’s Wifi libraries.
- In the middle is the ESP-32, the brain. I missed the WiFi interface of MK1, kinda annoying going back and forth to monitor the temperature and making sure the thermocouple stay in the water.
- KY-040 Rotary Encoder on the left. Another drawback of MK2, D-pad buttons are terrible interface to set temperature. Rotary encoder because that way I can have interface continuity between WiFi and the device
- Spare 16x2 LCD, already have the 0.96” OLED on order. Seen there is the encoder running to set the “target temperature” and the local IP address of the ESP-32.
The basic of DIY Anova has been done multiple times and there many guides on Instructables and YouTube, a temperature controller, small aquarium pump, and a submersible water heater. However, for some weird reasons most (if not all) of them use a bang-bang controller that’s really meant for a cooler than heater. Seriously, like $5-10 more you’ll get a PID controller. See the graphs below, bang-bang is far from ideal for a Sous Vide.
To be continued...