Temperature Data logger

Hi I would like to construct a datalogger using Arduino

In my project, I need to monitor the temperature of water in a container. I need to place 4 thermocouples on the outside of the container and place 2 thermocouples inside the container filled with water (the thermocouples will be immersed in water/ice) and another to monitor the atmosphere/surrounding temperature. I will then place the container in the refrigerator and monitor the water’s behavior as it changes the temperature with respect to time.

I want to assemble this logger using Arduino components since they are inexpensive, using k-type thermocouples or others that are recommended. I am confused because the youtube videos I watch use components such as amplifiers. Or alternatively, I can use a Raspberry Pi

can I ask for assistance on which components to order for this?

Hi bongi,

Welcome to the Tech Forum!

The reason you are seeing amplifiers in those thermocouple circuits is that thermocouple signals are in the micro-volt range. An Arduino can’t resolve such small voltages directly. Measuring thermocouples are very tricky without the proper signal conditioning.

Fortunately, several manufacturers make IC’s designed to take care of the difficult parts of dealing with thermocouples. For instance, Maxim makes a nice chip called the MAX31856 which can handle many types of thermocouples and outputs a digital signal via SPI, which interfaces nicely with an Arduino.

Since you are planning to use several thermocouples, you will need several of these chips. However, with SPI, you can use the same Arduino MISO, MOSI, and clock lines to communicate with all of the MAX31856 chips and use one extra I/O pin for each “Chip Select” pin of the chip you wish to communicate with.

Adafruit makes a breakout board for the MAX31856 which allows one to prototype without having to spin a board, shown here: