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ADC Converter

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Reloadron

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The Vout is going to be a DC level proportional to the AC excited Wheatstone Bridge output. I think you need to do some reading and understand what an ADC is and how it works. The DC level applied to the ADC is very much an analog signal. The LF351 operational amplifier is a pretty old chip, today there are much better solutions, including a wide range of instrumentation amplifiers better suited for your drawing. Your drawing serves more as an example than a practical application circuit. Using a uC (micro-controller) with an ADC (Analog to Digital Converter) you write code for the ADC to convert a DC level input to some engineering unit.

Ron
 

Minh Thanh

New Member
The Vout is going to be a DC level proportional to the AC excited Wheatstone Bridge output. I think you need to do some reading and understand what an ADC is and how it works. The DC level applied to the ADC is very much an analog signal. The LF351 operational amplifier is a pretty old chip, today there are much better solutions, including a wide range of instrumentation amplifiers better suited for your drawing. Your drawing serves more as an example than a practical application circuit. Using a uC (micro-controller) with an ADC (Analog to Digital Converter) you write code for the ADC to convert a DC level input to some engineering unit.

Ron
Could you share some information about ADC to me ? I researched a lot but I didn't still understand relationship between DC level and AC
 

alec_t

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An ADC converts an input voltage (which may be a fixed or varying DC level or an alternating AC signal) into a digital number represented by a set (e.g. 8 or 10) of binary bits.
 

Reloadron

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Could you share some information about ADC to me ? I researched a lot but I didn't still understand relationship between DC level and AC
Let's try using an example. I have a whetstone bridge or any sensor circuit. My sensor measures 0 to 10 PSI (Pounds per Square Inch) or pressure. After signal processing and signal conditioning let's say my pressure transducer (pressure sensor) is a 0 to 500 PSI sensor and outputs 0 to 10 volts. Now 0 to 500 PSI is represented by 0 to 10 volts.

Note what Alex mentions above:
An ADC converts an input voltage (which may be a fixed or varying DC level or an alternating AC signal) into a digital number represented by a set (e.g. 8 or 10) of binary bits.
So if I have a 10 bit A/D converter I have 2^10 or 1024 bits. Meaning the Full Scale analog input of my A/D will have 1024 quantization levels. Using for example an A/D converter with a 10 Volt full scale input and 10 bit conversion My code to read my input would look a little like this:
(Analog Input / 1024) * 500 = PSI Using my transducer example so if I apply 250 PSI to my transducer it will output 5 volts which would be 512 bits so we get:
(512 / 1024) = 0.5 * 500 = 250 so there is my 250 PSI in Pressure engineering units.

Before understanding A/D conversion (There is much, much more to it than this simple example) one needs to understand engineering units of measure and how to convert those units. This all starts with an understanding the basic principals of electronics.

Ron
 

ci139

Active Member
understanding the basic principals of electronics
unless you don't want to explain us all what is electric charge -- it is something understanding the basic robust time scale bulk statistical behaviour and some energy relations with known physics . . . of the charged particles - - besides i don't follow your ADC bits quite well the [ s ] tag enables error indication [edit] button enables . . . any second opinions
. . .
not that passing a naming error would be something over critical but that it may take quite a while for a novice to figure out that your 1kb actually stands for 1k quantization levels
---
understand relationship between DC level and AC
? the energy changes in AC versus in it's rectified (? and scaled) DC characteristic level
example AC sine /¯\_/¯\_/¯\_ , AC square wave |¯|_|¯|_|¯|_|¯|_ , AC pulse-train __∥___∥___∥___∥_ -- all have peak voltage , offset (from weighed balance/zero level) an average absolute offset voltage -- the least is 4/(2π) = 2/π = 1/(π/2) for sine , 1 for square wave if both are deviated ±1V from zero volts . . . since the real square waves and pulse trains are trapezoidal the average abs deviation becomes less than 1 ; -- PS! for pulse train it is additionally the function of it's duty cycle - e.g. - Zero or infinite corrected 1(=100%) duty give the steady level of DC with ±0V AC component - thus avg.abs.offs. = 0 . . . while the 50% duty gives the square wave - and avg.abs.offs. ≾ 1 . . .

in images
 
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ci139

Active Member
There is no analog signal . It is DC , so How can I convert ADC for output of Vo ?
as a programmer - finding the bugs is mostly what i have been doing in the past . . .
c:\computing ...
There is no analog signal . -- ? There is no (emediate) signal analogy (in between ADC I/O). /* versus */ There is no AC signal. /* versus*/ There is no analog signal (at the output of ADC).
It is DC , so How can I convert ADC for output of Vo ? -- It is Digital , ... How can I configure the ADC to output the ... ?
? would make sense in this context - but is that what the question ®-ly was
there is no web examples i can find . . . today . . . it seems nasa has "(failed)-to-utilize" the MAX1089 in very briefly covered in pg.6 to 8
 
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Reloadron

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not that passing a naming error would be something over critical but that it may take quite a while for a novice to figure out that your 1kb actually stands for 1k quantization levels
I thought in my case my 1K was actually 1024 quantization levels? 0 to 1,000 would be 1024 steps. I tried to use a simple explanation based on the original post. Since my attempt was not very good maybe you should explain it so the original poster can understand.

Ron
 

ci139

Active Member
Since my attempt was not very good
using "bits" insted of "steps" or "x-levels" does not make it "not very good" you're overreacting -- i usually read my post before/+after publishing -- scanning the logic/context and syntax errors -- fix ASAP

+ i know that many members here don't like to stay on subject but rather do anything else (like and this one) -- so i only attempted to save yet another such situation

more precisely
  • you passed a bug -- that you were unlikely to fix -- usually i don't care but this time i set 1-time notice - (i'm not any ones babysitter)
  • about multiple scanning the post for errors
    • after posting the visual pattern / layout of the text changes
    • the human reads 1-st/+last char and guesses the ones in between checking their existence but not the exact order
    • buy reading the "familiar" text you likely read it also from your mind/memory
    • . . . so after pattern change you more likely need to refresh your "memory image" buy reading more exactly the "new version" of it
    • - so the possible bugs are more likely to be recognized that way
 
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