Sample and hold circuit

Discussion in 'The Projects Forum' started by bobmcm, Jan 11, 2007.

  1. bobmcm

    Thread Starter New Member

    Jan 11, 2007
    4
    0
    I need a circuit to hold the last 4-20 ma dc signal until it receives a new signal.

    This is for a pressure tester.

    The pressure is increased untill the test subject ruptures, and the
    pressure transducer signal signal drops to 4 ma, I want to hold the
    signal value at the point of rupture until it is manualy reset or receives a new signal.

    Any help would be greatly appreciated.

    Thank you in advance.

    bobmcm
     
  2. n9352527

    AAC Fanatic!

    Oct 14, 2005
    1,198
    4
    What you probably need is a peak detector instead of just a S&H. Usual implementation is a precision rectifier followed by an opamp. You could also go with an IC that does all these, like PKD01 from Analog Device.

    You have to convert the 4-20mA signal to voltage first.
     
  3. ronv

    AAC Fanatic!

    Nov 12, 2008
    3,282
    1,240
    Hi Bob,

    If you want to send me an e-mail address I will send you a circuit. I'm guessing you can measure the result with a voltmeter and that the build up of pressure happens fairly slowly.
    Is powerpoint okay?

    Ronv@wbhsi.net
     
  4. ronv

    AAC Fanatic!

    Nov 12, 2008
    3,282
    1,240
    Hi Bob,
    If you want to send me an e-mail address I can send you a circuit. I assume you can measure the output with a voltmeter and that the pressure builds up fairly slowly.
    I'd paste it here but I don't know how.
    Is Powerpoint okay?

    Ronv@wbhsi.net
     
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