Thermocouples are temperature sensors widely used, but the reliability of the values indicated by them must be constantly checked. When the tolerable error limits are exceeded or when one wishes to increase the reliability of results, calibration should be performed. This text will address what are the main sources of errors in thermocouples and what are the ways to calibrate them. By a calibration, it was performed an improvement in LDA Arduino software, which now includes the Equation of a fitting curve in your source code, sending information to the system Lorscheiter Viewer correlated with a measuring instrument calibrated by a certified laboratory.

This work was carried out as an exercise in developing open source software to interface with free hardware. In this work a software was developed to perform serial communication between a computer (PC) and the Arduino, aiming at the simultaneous recording of two temperatures measured by type K thermocouples as a function of time. The temperatures measured by the analog instruments, thermocouples type K, were converted into digital signals through the MAX6675 and sent to the PC via the Arduino serial port. At the computer these data were expressed graphically in real time through the application developed for this purpose and then stored in files compatible with spreadsheets for subsequent mathematical analysis.