help with lower RC time of sensor

Discussion in 'The Projects Forum' started by david1234, Sep 16, 2014.

  1. david1234

    Thread Starter Member

    Nov 27, 2013
    81
    1
    Hello
    I have this circuit which give me "0" whenever it "see" movement
    using a PIR sensor

    now I want to reduce the output time
    now the time is about 3.5 seconds
    where I need to change to reduce it to ~1 seconds?
    from some reason I can't upload the image
    this is the circuit
    http://www.kube.ch/downloads/pdf/kube_pir_demonstrator_tr256.pdf
    [​IMG]
     
    Last edited: Sep 16, 2014
  2. crutschow

    Expert

    Mar 14, 2008
    13,006
    3,232
    Off hand it would appear that reducing the value of C1 in the schematic would reduce the response time accordingly. But capacitors C4 and C5 may also affect the response time.
     
  3. Bernard

    AAC Fanatic!

    Aug 7, 2008
    4,172
    397
    To me a strange connection- OP Amp + input tied to Comp. - input with no V ref. other than a cap. to gnd.
     
  4. Sensacell

    Well-Known Member

    Jun 19, 2012
    1,129
    266
    PIR sensors are inherently slow, FYI.
     
  5. #12

    Expert

    Nov 30, 2010
    16,283
    6,795
    I'm looking at C2, C6, and C7 for a time constant of more than a second, but that schematic is very hard to make sense of.
     
  6. david1234

    Thread Starter Member

    Nov 27, 2013
    81
    1
    I have another schematic but I can't upload it
    when I press "Upload a File" it do nothing
     
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