Converting ADC for DC Output: Homework Statement and Solution

[Minh Thanh]

Homework Statement

There is no analog signal . It just is DC . How can I convert ADC for output of Vo ?

Homework Equations

The Attempt at a Solution

 

[lewando]

Say V_o is at 2 VDC. Why do you think this is not an analog signal?

 

[berkeman]

There is no analog signal . It just is DC . How can I convert ADC for output of Vo ?

It looks like that Vo can change slowly as the Wheatstone Bridge output signal changes. Can you describe what is going on in each stage of this circuit? And estimate the signal out of each stage's output?

 

[Minh Thanh]

Say V_o is at 2 VDC. Why do you think this is not an analog signal?

Because my multimeter shown a fixed value when it's mode is DC meter.

 

[CWatters]

What were you expecting the meter to show?

 

[berkeman]

Because my multimeter shown a fixed value when it's mode is DC meter.

Your multimeter uses an ADC to figure out the measured voltage, BTW. Did you know that?

 

[Minh Thanh]

Your multimeter uses an ADC to figure out the measured voltage, BTW. Did you know that?

No .. I mean is that my multimeter reads a value of voltage from output of Vo and I guess that is DC voltage . :D :D The multimeter has no an ADC in itself.

 

[berkeman]

The multimeter has no an ADC in itself.

http://www.circuitstoday.com/wp-content/uploads/2009/12/ICl7107-voltmeter-circuit.png

 

[lewando]

If your multimeter looks like this:

then

The multimeter has no an ADC in itself.

would be a true statement.

 

[Minh Thanh]

If your multimeter looks like this:
View attachment 209932
then
would be a true statement.

That is right . I am using it .

 

[lewando]

Because my multimeter shown a fixed value when it's mode is DC meter.

Why do you think a fixed value is not an analog value? If you think an analog signal needs to be a time-varying signal in order to be converted by an ADC, then that is not a complete understanding. The definition of an analog signal includes signals that do not appear to change over time. For example: the signal that represents the mass of something when placed on an electronic scale is an analog signal.