K-Type Thermocouple with MAX6675 Amplifier
In the article, you can learn how to check the temperature using a K-Type Thermocouple with the MAX6675 amplifier using the Arduino board. A K-type thermocouple is a kind of temperature sensor with a big measurement range like −200ºC to 1350ºC (−326 to 2300ºF).
The guide talks about how to compare the k-type thermocouple with the Arduini board. And the installation process of the needed library and using a simple design to show the sensor readings in the Serial monitor.
Table of Contents
In this guide, we are covering the below topics.
- Introduction of the thermocouple
- MAX6675 Amplifier
- Cooperating K-Type Thermocouple with MAX6675 Amplifier
- Installing MAX6675 Arduino Library
- Code – Getting Temperature from K-Type Thermocouple with MAX6675 Amplifier.
What is a K-Type Thermocouple?
A thermocouple is a tool that has got two different electrical conductors that make an electrical junction-thermal junction. The changing of the temperature in the junction makes a somewhat quantifiable voltage at the reference junction that is able to measure the temperature.
We can make an A thermocouple using different hardware. The hardware we use acts on the voltage range, cost, and sensitivity. The normalized hardware combinations result in many thermocouple types: B, E, J, N, K, R, T, and S.
The guide is about the k-type thermocouple. the k-type thermocouple is built of chrome and alumel conductors. It has got a standard range of temperature from -200 to 1260ºC (-326 to 2300ºF).
MAX6675 Amplifier
To have the temperature from the thermocouple we have to get a thermocouple amplifier. The temperature that comes out from the thermocouple amplifier hangs on the voltage read on the reference junction. The voltage at that junction is based on the temperature difference between the reference junction and the thermal junction. So we should know the temperature at the reference junction.
The MAX6675 thermocouple is built up with a temperature sensor to count the temperature at the reference junction and expands the tiny voltage at the reference junction. There it is able to read using the microcontrollers. The MAX6675 amplifier links with a microcontroller using an SPI communication protocol and gets the data in a 12-bit resolution.
Very often, you can receive a pack with a k-type thermocouple and the MAX6675 amplifier. There is a list of the MAX6675 most common attributes.
- Converting directly the k-type thermocouple outputs into digital.
- Cold-junction reparations
- Simple SPI conformable serial interface.
- Steering voltage range: 3.0 to 5.5V
- Steering temperature range: -20 to 85ºC
- Sorting out the temperature to 0.25ºC lets readings as high as 1024ºC (1875ºF).
Interfacing K-Type Thermocouple with MAX6675 Amplifier
As said earlier, the MAX6675 links with a microcontroller using SPI communication protocol.
Get Temperature from K-Type Thermocouple with MAX6675 Amplifier
In this part, you can learn how to receive the temperature from the k-type thermocouple. We are showing you a small example that reads the temperature and shows sits on the Arduino IDE Serial Monitor.
Parts needed
For the completion of the guide, the below parts are essential for you.
- K-type thermocouple with MAX6675 amplifier
- Arduino (read Best Arduino starter kits)
- Jumper wires (female-to-male)
Use the earlier links or go to MakerAdvisor.com/tools to get all parts from the projects.
Schematic – Arduino with K-type thermocouple and MAX6675 Amplifier
Link the MAX6675 Amplifier to the Arduino as you see in the below-simplified diagram.
Follow the below table.
Installing MAX6675 Arduino Library
There are lots of libraries to have the temperature from a K-type thermocouple with the MAX6675 amplifier. We are using the max6675 library from Adafruit.
Follow the below steps for the installation of libraries of the Arduino IDE.
Open the Arduino IDE and head to Sketch > Include Library > Manage Libraries. Next, the Library Manges will be opened.
Search the “max6675 ” using the search box and install the library from Adafruit.
Code – Get Temperature from K-Type Thermocouple with MAX6675 Amplifier
It is very simple to get the temperature from the thermocouple using an Arduino. The library gives some examples that receive the temperature and shows the results on the Arduino IDE Serial monitor.
How the Code Works
First of all, enter the max6675.h library.
Design the pins that are cooperating with the MAX6675 thermocouple amplifier.
Build up a MAX6675 object name as a thermocouple on the pins that are designed earlier.
In the setup, format the ZSerial Monitor at a baud rate of 9600.
In loop(), we record the temperature and show it on the Serial Monitor. The library gives the procedures to read the temperature in Fahrenheit degrees.
- thermocouple.readCelsius():Displays the temperature in Celsius degrees.
- thermocouple.readFahrenheit(): Displays the temperature in Fahrenheit degrees.
The below lines show the temperature and make appearing on the Serial Monitor.
As you will see, it is easy to get temperature readings with the K-type thermocouple using the MAX6675 amplifier.
Demonstration
Upload the code into the Arduino board. Do not forget to select the board that is being used in Tools > Board and choose the COM port that you have connected to the board in Tools > Port.
After you have uploaded the code, go to the Serial Monitor at a baud rate of 9600.
You can see the new temperature records in the Serial monitor displayed in every seconds.
Wrapping Up
In this article, you got to know how to read temperature using the k-type thermocouple with the MAX6675 amplifier. Thermocouples have a big variety of temperature measurement ranges and lest you read the high temperatures are as high as 1024ºC (1875ºF) when the thermocouple is used with the MAX6675.
Frequently Asked Questions
How calculate the accuracy of thermocouple accuracy ?
The higher of the two tolerances given can be used to check a thermocouple’s starting accuracy. Note that the same method is used to determine thermocouple standards and special tolerances. Divide 300 °C by 0.0075 to get 2.25 °C.
What type of Thermocouple is best?
Type E. The Type E thermocouple can be used in a vacuum, static, relatively oxidizing, or reducing atmosphere at temperatures up to 900°C (1650°F). The thermocouple does not rust when the temperature is subzero. Of all the thermocouples, this one has the highest EMF output per degree.
How to know the K-type thermocouple I have?
In the amplitude, or continuity modes, you can see a low resistance measurement on a reliable thermocouple. More than a few amplitudes show a reasonably false thermocouple. You have an RTD on your hands if the reading at room temperature is close to 110; continue reading.
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