Sensor problem....

Discussion in 'The Projects Forum' started by Lithos, Jan 14, 2012.

  1. Lithos

    Thread Starter New Member

    Sep 10, 2011
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    Hello!
    I am embarrassed because I had this thread for a long time and I didn't respond...
    Sorry for that as I was abroad for a long time...
    Finally I managed to put this into an oscilloscope for finding out input and output signals.
    So this is what I came out with:
    [​IMG]

    SgtWookie, helped me a lot with the previous one, so I am counting on him :)
    One thing I want to say is that I want the output voltage to be managed by a capacitor (to avoid ICs), and the circuit can be more simple.
    I am trying to use basic components as resistors, capacitors etc for this...

    Any help would be accepted!
     
  2. evilclem

    Member

    Dec 20, 2011
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    What exactly are you trying to do?
     
  3. Lithos

    Thread Starter New Member

    Sep 10, 2011
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    I am trying to emulate the output, when I have the input signal that I posted!
     
  4. wayneh

    Expert

    Sep 9, 2010
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    It's not clear whether the the input and output are linked, though I assume that is your goal. What logic/condition produces the output?
     
  5. Lithos

    Thread Starter New Member

    Sep 10, 2011
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    Of course and they are linked, as you can see on the bottom graph...
    When I open the switch the input signal in the graph, pass through the "box" and the box creates the output that I want to emulate...
    If the output is like the output signal in the graph, then the sensor doesn't return fault, if it has another output I get the error...
     
  6. joeyd999

    AAC Fanatic!

    Jun 6, 2011
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    You cannot get the linear response you are looking for with just Rs and Cs. You need a constant current integrator, usually using an op amp.

    You could use two current sources through a digitally controlled analog switch, but that still violates your 'no IC' requirement.

    EDIT: Also, your ramp waveform is not synchronized with your original squarewave input. This 'non-linear' (i.e. output frequency fundamental != input frequency fundamental) transformation cannot be done with passive components.
     
  7. SgtWookie

    Expert

    Jul 17, 2007
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    I really don't have anything more to add to joeyd999's statements, as he's correct.

    I gave you an opamp solution in the other thread, but that was a straight-line solution; this one would be different.

    I am in the hospital recovering from heart bypass surgery. I don't have a "real" computer available to work the problem on. Perhaps someone else will assist you.

    Lastly, you sent me an off-line E-mail with bad links to this thread, and no way to reply to your Email as you have E-mail turned off. I'm going to have a Moderator turn your E-mail and PM's on to prevent that annoyance to another member.
     
  8. Lithos

    Thread Starter New Member

    Sep 10, 2011
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    I wish you well recovery SgtWookie!
    Sorry for the inconvenience I didn't saw your signature about PMs...
    I will try with op-amps...
     
  9. SgtWookie

    Expert

    Jul 17, 2007
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    Thank you.

    If it is a thread that I have already participated in, and that more information later provided hasn't been acted on by myself over a period of sevearl days, then a PM to request a look at a given thread would be warranted. I wasn't complaining about your current PM. What I found really annoying, is that the link you provided to the thread was incorrect, and I could neither PM nor E-mail you to find out what you were talking about.

    [/QUOTE]I will try with op-amps...[/QUOTE]

    Using proper opamps will be helpful to getting a good start. However, the kind of response you are looking for is not a straight 1:1 correlation - you will need to use more than just op-amps with passive componenets.
     
  10. Lithos

    Thread Starter New Member

    Sep 10, 2011
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    I think that the input acts as a trigger to an internal circuit that is powered through the source of 5 Volts.
    So I am thinking using the source of 5Volts, pass it through a voltage divider to 3.5 Volts and then try to decrease and increase the voltage.
    Also I suspect that the output timing doesn't matter the sensor, but just the lower (0Volts) and upper (3.5Volts)...:confused:
     
  11. Lithos

    Thread Starter New Member

    Sep 10, 2011
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    If I had this graph:
    [​IMG]
    How can I make it?
     
  12. Georacer

    Moderator

    Nov 25, 2009
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    This is output waveform is very different from the first one. Not only the changing points between input and output match, but it also has an initial value.

    In this case, your system can be an active circuit, a Miller integrator. Have a read here, in the integrator section: http://www.allaboutcircuits.com/vol_3/chpt_8/11.html
     
  13. Lithos

    Thread Starter New Member

    Sep 10, 2011
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    What op-amp should I put, if I have to use this DC Voltage?

    [​IMG]

    I also want the op-amp to be cheap and easy to find....
     
  14. Lithos

    Thread Starter New Member

    Sep 10, 2011
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    I have tried LM741 in multisim, but the output goes to some kVolts... !!!!!!!
    Any help on that?
     
  15. Georacer

    Moderator

    Nov 25, 2009
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    What is your power supply? Can you post an image capture?
     
  16. Lithos

    Thread Starter New Member

    Sep 10, 2011
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    The power supply is a PIECEWISE_LINEAR_VOLTAGE (Multisim)
    And signal timings are 150ms, for fast simulation results...

    [​IMG]

    But when I use an LMC6484AIN, all is normal...
    [​IMG]
     
    Last edited: Jan 20, 2012
  17. Georacer

    Moderator

    Nov 25, 2009
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    Multisim has been caught before giving wrong results, for example driving the output of a 741 rail-to-rail. Maybe it's a bug.

    Someone else might have a better suggestion.
     
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