National Instruments BNC-208 Series, Руководство пользователя

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BNC-2081 Board Chapter 3
BNC-208X Series User Manual 3-14 © National Instruments Corporation
Example:
Using the values in Figure 3-12,
G =
10 k
Ω
10 k
Ω
+ 10 k
Ω
=
1
2
Therefore, V
Lab
= (1/2) V
SC
When the Lab board is configured for
±
5-V inputs, the board can acquire
±
10-V signals with this
attenuator circuit. The input impedence of the circuit is 10 k
Ω
+ 10 k
Ω
= 20 k
Ω
. The source impedence
of the circuit is as follows:
10 k
Ω
10 k
Ω
= 5 k
Ω
.
Lab Board Analog Output
Analog output BNC connectors each have two open component positions for optional signal
conditioning components. One of these is designated as a resistor and the other as a capacitor. The
equivalent circuit for DAC0 OUT is shown in Figure 3-12. Circuitry for DAC1 OUT is the same.
When the board is shipped, 0-
Ω
jumpers are inserted into the
R17
an
R18
positions. These can be easily
removed to build passive analog output signal conditioning circuits such as voltage dividers and lowpass
filters. Figure 3-12 shows the DAC0 OUT schematic. Figure 3-13 shows the analog output schematic
for DACs with DAC0 OUT shown.
BNC Connector
DAC0 OUT
AOGND
R17
C1
Jumpers Installed
Here at Factory
DAC0 OUT
Figure 3-12. DAC0 OUT Schematic