build Measure capacitances

Discussion in 'General Electronics Chat' started by pini200, Feb 15, 2016.

  1. pini200

    Thread Starter New Member

    Feb 15, 2016
    14
    0
    hello
    I need to build device that Measure capacitances
    the range of capacitance is 50nF-300nF
    What's the best way to achieve accuracy
    (I think use in 555 and how i build this )
    thanks


     
  2. AnalogKid

    Distinguished Member

    Aug 1, 2013
    4,546
    1,252
    There are many ways to do this. Three examples:
    You can apply a calibrated DC voltage or current step and measure the rise time of an R-C network.
    You can put the capacitor in an oscillator circuit and measure the frequency.
    You can apply a sinewave through a resistor and measure the attenuation caused by the capacitor.

    ak
     
  3. wayneh

    Expert

    Sep 9, 2010
    12,155
    3,061
    A 555 circuit can be used, but you need to think about what precision and accuracy you need. (These are not the same - consider both.) A 555 is not nearly as precise as a crystal oscillator and will limit the quality of your results. Depending on what you are doing, it may be fine.
     
  4. #12

    Expert

    Nov 30, 2010
    16,346
    6,835
    Trim pots. Include adjustment potentiometers so you can calibrate to something well known.
     
  5. pini200

    Thread Starter New Member

    Feb 15, 2016
    14
    0
    Thanks
     
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