For a long time now I have wanted to own a SlowCooker. Unfortunately, I couldn’t decide on which one I should get. I like the expensive ones where you can set the temperature digital but, being Dutch, there is no way I'm spending that kind of money!

Now I have a little more time on my hands due to the COVID-19 crisis, I decided instead to just make one myself. I had this ceramic hot plate lying around which I was already using for my pot roasts. And after diving into my parts collection, I dicovered all I needed to buy was a 4 euro temperature sensor!

It is great for making stews and pot roasts, or tempering chocolate au bain marie!

Supplies

Arduino Uno With Screw Terminal (Or any other type you have laying around)
DS18B20 TO-92 Thermometer - Waterproof with 1m cord
One 4,7KΩ resistor
I2C LCD Screen (I used a 16x2)
Small DC Power Supply (I used a Self Electronics SLT3-350IS-1 LED-driver)
5V Relay Module
Two-Way Momentary Switch
Power Socket with switch + Cable
Heating Element / (Ceramic) Hot Plate
Some PCB Board
Some form of housing for your SlowCooker

Step 1: Hooking Everything Up

If you have acquired all of your components, it is time to connect it all together. If you like you can set everything up on a breadboard first, or go straight forward to building up your SlowCooker. In any case, I’ve included a Fritzing diagram to explain how to connect all the parts. This is my first try at Fritzing, so I apologize if it’s not entirely clear…

In real life I connected my 12V power supply directly to the power socket with switch, so that everything can run off of 1 plug. I use the switch to turn off the device when it’s not in use.

Furthermore, I’ve soldered the resistor and the thermometer to a small piece of PCB board.

If you have got everything connected correctly upload the code to your
Arduino using the Arduino IDE.

n.b. In the pictures you can see I started out with an Arduino Nano but I forgot to unplug it while I was soldering, so I accidentally fried that one... Oh well...

SlowCooker.ino
Download

Step 2: Housing

Finally, you need some form of housing for all your parts. I chose to make a cube (120x120x120mm) out of 9mm multiplex with holes for the various external components. I have to admit: it’s not my best work, it's a little tight, but it does the trick.

A plastic container might also do well as a housing, but that’s up to you!

After you've put everything in your housing it's time to start cooking!

Good luck and have fun!