OP Amp analysis. I had this thrown at me and I have very little idea what is how to go about solving

Discussion in 'The Projects Forum' started by Dayton993, Apr 29, 2016.

  1. Dayton993

    Thread Starter New Member

    Apr 29, 2016
    Here's what I know. The circuit is measuring the current of a laser diode using a current mirror. for the analysis to make things easy assume 100ma is entering the system. I get confused about how the currents run through the circuit. I'm pretty sure the first op amp has a gain of -3.0. besides this I have no idea how to go about solving the gain of the second op amp etc. This all interfaces to a hotmux data logger that can handle a voltage of 0-50mv.

    I hope this is enough info. also Stepping through this would be fantastic.

    Thank you
  2. Papabravo


    Feb 24, 2006
    I can't help you if I can't read your schematic. That is perhaps the worlds' worst uploaded image. Do you seriously believe we can help if you feed us garbage like that?
  3. wayneh


    Sep 9, 2010
    Huh, I can read it OK once I click to get the full resolution.

    What I'm missing is the question, the goal.

    One thing I can tell you is that you don't have 100mA flowing in the circuit as shown. There's nowhere for it to go. I see 90kΩ plus a diode for the path of least resistance.