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  1. #1
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    audio amplifier circuit

    hello guys
    iam eletronic student ....currently i doing one project with audio amplifier and LED.

    i need to design a 0.5w audio amplifier with mute and volume control....the design should allow user to select two different bandwidth....selected choice must be indicated visually using LED...the power supply is +- 12V ...the leval of baseband signal is 250mv pk to pk at 1khz...

    components should be used ...MicroA741. TDA7052A, regulator (LM78, L05), transistor 2N2222......
    plese guide me on how to design the circuit board....
    i need u r help very urgently...thanks in advance...

    •   Alt31st January 2009, 11:32

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  2. #2
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    audio amplifier circuit design

    Since you say you need help designing the board, I assume you already have the circuit designed. You need to do the schematic with parts values calculations before you think about the board layout.

    If you have specific questions about parts of your circuit for which you haven't been able to find answers, you can post them, and you'll get help.

    When your schematic is done, and you're trying to lay out your circuit board, you can post specific questions, and you're likely to get help on that as well.

    I can't speak for others on the forum, but I'm not willing to do your homework for you. I already did this kind of project by myself when I was learning. Ask specific questions, and I'll be glad to help where I can.



    •   Alt31st January 2009, 21:04

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  3. #3
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    design audio amplifier

    I think the school kid wants somebody to do his homework for him.



    •   Alt1st February 2009, 01:09

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  4. #4
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    amplifier circuit design

    Thank you so much for your reply:D
    my group was able to design a circuit for our topic...we think there could be some minor faults in ckt.we are supposed to use only 1bandpass filter..and v should not use it for music.now the main problems in our ckt are:

    *only two switches must be used,but in our ckt we don't knw which one 2 omit as there are 3switches.

    *what is supposed to be done in between the frequency supply and the music's BJT?whether a resistor or some other device to be used there?

    *when we test our ckt,do we need to test part by part(op-amp by op-amp)or we can directly patch up the whole things and test for the output?

    we have attached two ckt diagrams with this post..the one with red circles was done by us(which is 2 b corrected)
    If the other one is more accurate and workable than ours..pls try 2 modify it for us.
    pls kindly reply to me ASAP..it would be really helpful if do this favour for us.



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    amplifier circuit

    A transistor does not pass a signal from its collector to its emitter. It passes a signal from its base to its emitter. But then its output DC level will change when it is turned on and off and it will make a huge POP in the speaker.

    I think the transistors should short the unwanted signal to ground.

    A single opamp can be used for the extremely simple filter. Use the first opamp with its input a highpass filter and add a capacitor across its feedback resistor to make thew lowpass filter.
    then the second opamp can buffer the signal souce and feed a resistor that can be shorted to ground by a transistor to mute the music.

    The TDA7052A amplifier IC will get too hot when it has a 12V supply and is bridged with an 8 ohm speaker. it has a 6V supply in its datasheet but will be fine with a 12V supply and a 16 ohm speaker.

    Understand?



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