Signal Conditioning

Discussion in 'General Electronics Chat' started by RoyalDeviLz, Jul 1, 2014.

  1. RoyalDeviLz

    Thread Starter New Member

    Jun 24, 2014
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    What kind of signal conditioning circuit I should use to adapt a 0~5V output from a sensor (varies in resistance 100k+-). Anyone have any suggestion?
     
  2. Papabravo

    Expert

    Feb 24, 2006
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    Buffer the output with a voltage follower.
     
  3. wmodavis

    Well-Known Member

    Oct 23, 2010
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    " What kind of signal conditioning circuit I should use to adapt a 0~5V output from a sensor (varies in resistance 100k+-). Anyone have any suggestion? "

    What kind of conditioning depends on several things some of which you have given us no clue about.

    1. Characteristics of the signal of interest which you are monitoring with the sensor. Other than 0-5V what about rate of change, noise, etc.

    2. Type and characteristics of the sensor your are using to monitor the physical quantity of interest.

    3. What you intend to do with the signal from the sensor for instance what data you need to extract and how you will process the data extracted.

    Perhaps a bit more info about it would be helpful.
     
  4. Alec_t

    AAC Fanatic!

    Sep 17, 2013
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    Adapt it to suit what?
     
  5. RoyalDeviLz

    Thread Starter New Member

    Jun 24, 2014
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    Ok, I'm testing the characteristic of a graphite sensor using on 2B pencil and paper, the graphite piezoresistive varies the resistance from 50k~150k ohms. Initially i use wheatstone bridge + instrumentation amplifier circuit, but i found that the output i get remain at 4V all the time even the resistance varies alot, I really dunno why... I need to make a signal conditioning circuit that able to provides me the resistance that varies from 50kohms to 150ohms will equivalent to the range of 1V to 5V output. The data will be converted to digital signal by arduino ADC and display the spectrum on matlab using FFT. I really wish there's someone out there could help me with all of these... >.<
     
  6. Papabravo

    Expert

    Feb 24, 2006
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    Help us to help you by providing us with some minimal information. Your verbal description does not convey much useful information, at least to me. Let us start with a schematic diagram that shows how the sensor gets power and how the output is presented to the "signal conditioning" circuitry
     
  7. RoyalDeviLz

    Thread Starter New Member

    Jun 24, 2014
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    I have attached my circuit in the attachment, U3 will be my output from my amplifier, and R11 is where my sensor placed which varies in resistivity, i wan to build this circuit in such as the output in U3 will be very sensitive to the resistance in R11.
     
  8. ericgibbs

    AAC Fanatic!

    Jan 29, 2010
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  9. RoyalDeviLz

    Thread Starter New Member

    Jun 24, 2014
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    that's also my post.. ><
     
  10. djsfantasi

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    Apr 11, 2010
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    OP = Original Poster, BTW
     
  11. Alec_t

    AAC Fanatic!

    Sep 17, 2013
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    Can I suggest a different approach? You could use the variable resistance to control the frequency of a simple oscillator then measure the frequency with an mcu. Simulation is straightforward.
    Like this:
     
  12. inwo

    Well-Known Member

    Nov 7, 2013
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    Passive approach.

    " varies the resistance from 50k~150k ohms"
     
    Last edited: Jul 2, 2014
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