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  1. #1
    noo
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    Lm 380 audio amplifier

    hi... i am using Lm 380 audio power amplifiers in my project....m considering condenser mic as an input....as my voice is not getting amplified and not hear at the speake r..which cirxuit should i used in order to get the sound at my ouput..the circuit is not detecing the input voice..plzz help me out

    •   Alt20th October 2013, 18:12

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    Re: Lm 380 audio amplifier

    The LM380 has quite low gain but I'm suprised you get nothing out of the speaker. It may not be very loud but you should hear something. Please post your schematic.

    Brian.
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  3. #3
    noo
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    Re: Lm 380 audio amplifier

    Ya actually m just getting noise at output ....the input from the microphone is not heard at the speaker..



    •   Alt21st October 2013, 19:17

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    Re: Lm 380 audio amplifier

    If you are getting noise you have amplification so it should be working.
    Check you have the microphone wired the right way around, they are polarized, and make sure you are supplying it with sufficient operating voltage. Typically you need a resistor of 4.7K - 10K from the output pin to a positive supply voltage.

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  5. #5
    noo
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    Re: Lm 380 audio amplifier

    can you just give me a preamplifer circuit for condenser microphone
    through which i can get the ouput .plzzzzzz



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    Re: Lm 380 audio amplifier

    You probably have an electret microphone which is a condenser mic that has the 48V permanently stored in the electret material and it has a Jfet impedance reducer inside that needs about 0.5mA through a resistor at a low voltage.

    There are hundreds of preamp circuits for an electret mic in Google.



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    Re: Lm 380 audio amplifier

    Noo, please post your schematic. There is no way we can diagnose your problem from your description. As I pointed out earlier and Audioguru has confirmed, it appears you are not connecting the microphone correctly but unless we know how it's wired at the moment we can't tell you where the error is.

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  8. #8
    noo
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    Re: Lm 380 audio amplifier

    thkz to both of u i got the output.....thkz a lot.hope you will help me in future

    - - - Updated - - -

    yaaa it was problem in mic



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