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SC-2070 Board
Chapter 2
SC-207X Series User Manual
2-18
© National Instruments Corporation
+ Channel
- Channel
+5 V
AIGND
To
Input
Multiplexer
+
-
A
D
E
F
G
1
µ
F
10 k
Ω
10 k
Ω
10 M
Ω
100 k
Ω
Channel 1
Channel 9
R11
R8
R7
C3
R10
R12
(10 k
Ω
)
(- in)
(+ in)
Component Positions
Input Schematic
R9
(10 k
Ω
)
1
µ
F
10 k
Ω
Resistor
10 M
Ω
Resistor
10 M
Ω
100 k
Ω
1
µ
F Capacitor
100 k
Ω
Resistor
Figure 2-13. Thermocouple Circuit with Open Thermocouple Detect and
Lowpass Noise Filter
Selecting the Gain and Input Ranges
Because thermocouple output voltages are very low, a gain of 500 or 100 is usually necessary for best
resolution. The input range on the MIO-16 should be set to
±
5 V to improve resolution. These settings
can be used in all but a few cases, such as a fairly high output thermocouple type that is being used at
elevated temperatures. Table 2-3 lists the voltage extremes from several popular thermocouple types.
Use this table as a guide for determining the best gain and input range settings to use.
Summary of Contents for SC-207 Series
Page 15: ......