Opamp

Discussion in 'The Projects Forum' started by MDK, Apr 20, 2008.

  1. MDK

    Thread Starter Member

    Feb 1, 2008
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    I just built an opamp and all i can hear the music CD i played thru it but it makes it quieter and there is a buzz that is louder than the music.:confused:

    PLEASE HELP:(
     
  2. SgtWookie

    Expert

    Jul 17, 2007
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    For one thing, the opamp is connected as unity gain - that is, the output is looped back to the inverting input.

    Another thing is as drawn, the -9v is on the wrong side of two 1 Meg resistors that were meant to provide an artificial reference halfway between the +9 and -9 supplies.

    If you want the opamp to actually increase the signal level, it'll need to be wired differently.

    What is the amplifier IC that you are using?
     
  3. MDK

    Thread Starter Member

    Feb 1, 2008
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    it is a LM741CN opamp. could you please show me how to rewire it?
     
  4. thingmaker3

    Retired Moderator

    May 16, 2005
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  5. Audioguru

    New Member

    Dec 20, 2007
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    The lousy old 741 opamp is 40 years old. It is noisy, has a low bandwidth and its high frequency distortion is bad. It is not good for audio. A TL071 has the same pins and is much better.

    What is your opamp driving?
    Do you have a shielded audio cable for the input and output?
     
  6. MDK

    Thread Starter Member

    Feb 1, 2008
    22
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    To Audioguru,

    Would TL082CP chip work as well as the TL071?
     
  7. SgtWookie

    Expert

    Jul 17, 2007
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  8. MDK

    Thread Starter Member

    Feb 1, 2008
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    Ok, so i tried the exact same circuit just with the LM386 opamp it workd better, but it still is not making it louder it is making it a little bit quieter and it is distorting no matter what volume i have it at.

    Please Help
     
  9. gee_emm

    Active Member

    Jan 16, 2008
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  10. Audioguru

    New Member

    Dec 20, 2007
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    The LM741 is an opamp
    The LM386 is a power amplifier.
    They are completely different so they cannot use the same circuit. Circuits for the LM386 are on its datasheet.
    An opamp can drive a 2000 ohms or higher load. A power amp can drive a load down to 8 ohms.

    The TL071 is a single opamp that is a TL081 selected for low noise. The TL082 is a dual opamp with its pins numbers completely different. The TL072 is a dual opamp and is a TL082 selected for low noise.
     
  11. SgtWookie

    Expert

    Jul 17, 2007
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    I didn't mean for you to use the exact same wiring.

    You need to read the datasheet and follow the application guidelines. It's all spelled out for you right there.
     
  12. Digi Dave

    Member

    Apr 25, 2008
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