convert capacitance signal to voltage signal

Discussion in 'The Projects Forum' started by sumani, Mar 13, 2009.

  1. sumani

    Thread Starter New Member

    Mar 12, 2009
    8
    0
    hi..
    I'm an engineering faculty undergraduate, and new to this field. i m using HCH-1000 Capacitive Humidity Sensors for my project. now I'm facing a problem to connect it with PIC.
    i would like to know that how to interface this sensor with PIC micro controller. could you please suggest me a circuit diagram that can be used to connect humidity sensor HCH-1000-001 with the PIC 16f877a.

    or simply could you please suggest a circuit to convert capacitance signal to voltage signal
    capacitance varies in a range from 300 to 370 pF
    the required out put voltage is 2V-5V


    thank you
    R.SuManAroObAn
     
  2. thingmaker3

    Retired Moderator

    May 16, 2005
    5,072
    6
    You could use the sensor as part of an oscillator and feed o/p to a frequency-to-voltage converter.

    Or you could charge the sensor with a constant current source for a precise time interval and then sample voltage.

    Or you could use the sensor as part of a capacitive voltage divider with AC applied, and run the o/p through an RMS converter.

    Or you can do this: http://patft.uspto.gov/netacgi/nph-...50&s1=6331780.PN.&OS=PN/6331780&RS=PN/6331780
     
  3. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
    6,357
    718
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