B&B Electronics K-TYPE THERMOCOUPLE AMPLIFIER TCDA ユーザーズマニュアル

Documentation Number TCDA0997 Manual 

3 

 

  To understand the operation of the TCDA it is necessary to 
understand the basic construction of the thermocouple.  A 
thermocouple consists of two solid wires, composed of dissimilar 
metals, joined at one end.  The joining of dissimilar metals generates 
a small DC voltage based on the temperature of this junction.  The 
TCDA amplifies this small voltage to a usable level for A/D 
converters. 
 
 

The output of a thermocouple does not have a linear relationship 

with temperature.  A close approximation for a K-type thermocouple 
is 40.6

µ

V/

°

C.  This approximation is used with the TCDA.  Figure 2.1 

contains a plot of thermocouple output voltage over a temperature 
range. 
 

Actual thermocouple output

0

0

Temperature

O

(   C )

Ideal line (40.6uV/C)

O

u

tp

u

t 

V

o

lta

g

e

( 

V

)

This plot is not to scale, and the
nonlinearity has been exagerated.

0.0406

Note:

1000