B&B Electronics TCDA Manuale Utente

4 

Documentation Number TCDA0997 Manual 

 

 

The error caused by the thermocouple non-linearity over the  

-50

°

C to 200

°

C range is relatively small, so it is ignored in the 

factory calibration of the TCDA.  If more accurate readings must be 
taken, the following techniques can be used: 
 

1.   If all temperatures are taken near a certain temperature, 

calibrate the TCDA at that particular temperature. 

2.  Implement a look-up table in your software program to 

correct for error. 

3.   Use a piece-wise linear model for your thermocouple output 

to correct for error. 

 
  The terminal blocks on the TCDA and the leads of the 
thermocouple bead are made from dissimilar metals.  This creates a 
second, unwanted thermocouple at the terminal blocks. This 
unwanted thermocouple is called the cold junction.  The temperature 
of this cold junction will affect the results of the actual thermocouple.  
The TCDA has cold junction compensation that automatically 
corrects for small changes in the cold junction temperature.  It is 
important that nothing comes in contact with the terminal blocks or 
the two external diodes near the terminal blocks as this may cause 
large, rapid changes in the cold junction.  The cold junction should 
be kept at a constant temperature, if possible. 
 
 

Different types of thermocouples are made by joining a wide 

variety of metals. The TCDA is designed to amplify K-type 
thermocouple only. Thermocouples have a positive(+) and a 
negative(-) lead.  These two leads must be connected to the correct 
terminals on the TCDA module.  Connections will be covered in the 
next chapter.