What would cause the op-amp to behave like this?

Discussion in 'General Electronics Chat' started by ElectricMagician, Feb 2, 2013.

  1. ElectricMagician

    Thread Starter Member

    Jul 26, 2012
    57
    0
    Hi Everybody

    I'm experimenting with an inverting amplifier built around an LM386.
    Vout should be Vin * -5. Vin is a 440 Hz Tone.

    The output voltage is almost always Vin * 0.5, not Vin * 5!
    If I increase input the voltage (~1.5v), the output is even less than half the input.

    The circuit and the values are from my textbook. I checked multiple times that the circuit was constructed accurately. So, what would be causing this problem?

    - Damaged or faulty op-amp?
    - Op-amp unable to handle the 440Hz tone? (Datasheet says it's designed for audio amplification)?

    Thank you very much.
     
  2. timescope

    Member

    Dec 14, 2011
    298
    44
    The LM386 is not an op-amp. It is an audio power amplifier designed to drive a speaker and has special circuits to keep the dc output at half of the supply voltage.
    If you want to experiment with op-amps, use uA741, LM358, LF411 etc.

    Timescope
     
  3. ElectricMagician

    Thread Starter Member

    Jul 26, 2012
    57
    0
    So thats why! Thanks a lot for the advice!
     
  4. timescope

    Member

    Dec 14, 2011
    298
    44
    You are welcome.

    Timescope
     
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