“Because of the digital SPI interface of the sensor, MAX6675 amplifier data decoding is fast and more accurate and have long temp ranges.
A K-type thermocouple is a type of temperature sensor that is widely used in industrial applications to measure temperature. It is made up of two different metals, typically nickel-chromium and nickel-aluminium, which are joined together at one end to form a junction. When the junction is exposed to a temperature difference, a voltage is generated, which can be measured and used to determine the temperature.
In K Type Thermocouple positive leg is composed of 90% nickel, 10%chromium and a negative leg is composed of 95% nickel, 2% aluminium, 2% manganese and 1% silicon. These are the most common general-purpose thermocouple with a sensitivity of approx 41µV/°C.
The principle behind how a thermocouple works is called the Setback effect, which states that when two dissimilar metals are joined together at two different temperatures, a small voltage is generated. The amount of voltage generated is proportional to the temperature difference between the two junctions. The K-type thermocouple generates a voltage of approximately 41 microvolts per degree Celsius.”