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Linear opto coupler

Discussion in 'General Electronics Discussion' started by PRIYADHARSHINI, Nov 25, 2015.

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  1. PRIYADHARSHINI

    PRIYADHARSHINI

    137
    8
    Feb 6, 2014
    Hi all,

    I am using IL300 Linear opto coupler to isolate the analogue signals..Here I have attached the picture for four configurations of IL300..I m configuring my circuit as Non Inv input to Non Inv output...

    I have Designed my circuit for + and - 5 V as my supply.I attached my schematic design for your referance.And i got output at OUT1 as follows:
    for 0V input I got 2.4V at the 5 th pin(OUT1)
    for 5V input I got 4.43V
    In between this ranges the output will be linear.

    Now I want to consider the offset that is 2.4V should be reduces to 0v
    I need 0V for 0V input
    4.5V for 5V input.
    For this purpose the second stage of the opamp has been built.I don t know how to select the resistor values.they have given the formula.according to that i have selected my resistor values as 30K and 40K .but i got the output(OUT2) 4.01 V for 2.4V and 4.43V input.I don t know how to choose the values to clear the offset


    Thanks in Advance
     

    Attached Files:

  2. Harald Kapp

    Harald Kapp Moderator Moderator

    10,318
    2,238
    Nov 17, 2011
    You need to build a summing amplifier to eliminate the offset.
    Your configuration shows a non-inverting amplifier with a gain of ~2.3 which will drive the opamp into saturation (2.4V*2.3=5.5V, but the opamp cannot deliver more than ~4V).
    Note that the LM324's output cannot reach Vcc (+5V) but considerably less. The datasheet states for ecample that for V+=30V the max. output voltage may be as low as 27V! See also figure 10 in the datasheet.

    If you need to go up to 5V, you'lll have to use a rail-to-rail opamp, available from many manuifacturers.
     
  3. PRIYADHARSHINI

    PRIYADHARSHINI

    137
    8
    Feb 6, 2014
    Thanks for your reply.

    gain is 2.3 or 1.3???
    I have attached the four sets of configuration file.is it a summing amplifier or differential amplifier????
     
  4. Harald Kapp

    Harald Kapp Moderator Moderator

    10,318
    2,238
    Nov 17, 2011
    You can find that out using the standard equations for a non-inverting opamp amplifier.
    If you can't, then you haven't "designed" your circuit but simply copied without understanding how it or its parts operate.

    I don't understand your question. The diagrams are clearly labeled.
     
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