constructing an audio power amplifier circuit

Discussion in 'Homework Help' started by sakuragurl, Feb 5, 2009.

  1. sakuragurl

    Thread Starter Member

    Sep 27, 2008
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    Hey, i would like to ask how do you construct and audio power amplifier circuit using TDA2822M ?? can anyone show me a simple sketching of the circuit please?? Thanks!!
     
  2. beenthere

    Retired Moderator

    Apr 20, 2004
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  3. sakuragurl

    Thread Starter Member

    Sep 27, 2008
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    oh okay!! thank you so much for your help!:)
     
  4. Skeebopstop

    Active Member

    Jan 9, 2009
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    I don't get why in the stereo implementation they don't use the L and R differential inputs as differential. Aren't audio signals just differential? So why connect the - terminal of the audio amp through a de-coupling cap to common ground, and not signal -?
     
  5. Audioguru

    New Member

    Dec 20, 2007
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    Most consumer audio sources are not differential. They have one signal wire and one ground wire which is the shield.

    The (-) input of the TDA2822 is NOT the (-) terminal of the amplifier. It is a low impedance connection of its negative feedback. It would need to be buffered to have the same high input impedance of the (+) input. Then it would have a differential input.
     
  6. Skeebopstop

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    Wouldn't using your shiled as GND open you up to a lot of potential noise sources?
     
  7. Audioguru

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    Dec 20, 2007
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    The shield passes any interference to ground where it is not heard.
     
  8. Skeebopstop

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    Jan 9, 2009
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    I'm just thinking of for example comms applications, where the signal gnd is routed inside with the signals but there is still a shielding separate to this to protect all of them from EMI etc.. RS232 or USB for example.

    How is audio different? Low frequencies make it less susceptible to feeding EMI into your receiving end? After all, shields can only get rid of so much.. especially if connected to GND directly.
     
  9. beenthere

    Retired Moderator

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    It may be that the shielding you refer to is to keep the signals from radiating out. Lots of sharp edges on those square waves.

    USB is also a variant on LVDS, so not likely to pick up interference on low impedance twisted pair signal wires.
     
  10. sakuragurl

    Thread Starter Member

    Sep 27, 2008
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    hey, excuse me...what information can we include in the theory part of the circuit?? like how do we explain how the circuit works??
     
  11. sakuragurl

    Thread Starter Member

    Sep 27, 2008
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    hey, ...what information can we include in the theory part of the circuit?? like how do we explain how the circuit works?
     
  12. bertus

    Administrator

    Apr 5, 2008
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    Hello,

    On the page beenthere gave is also a link to the datasheet.
    The datasheet will give you a lot of information.

    Greetings,
    Bertus
     
  13. sakuragurl

    Thread Starter Member

    Sep 27, 2008
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    owh okay...thanks for your help!
     
  14. Audioguru

    New Member

    Dec 20, 2007
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    It is a simple stereo audio amplifier. Its schematic showing about 40 transistors is in its datasheet. It shows a darlington differential input, a voltage amplifier and a quasi-complementary output stage. It also has a bias circuit built-in.

    The schematic in the datasheet for the TDA2822M is very fuzzy. It is much clearer in the datasheet for the TDA2822.
     
  15. KL7AJ

    AAC Fanatic!

    Nov 4, 2008
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    One neat trick you CAN do with this, however, is to double your output power (in MONO mode) by driving the inputs and outputs differentially.

    But yes...for 99% of all consumer audio equipment, everything is single ended.

    eric
     
  16. Skeebopstop

    Active Member

    Jan 9, 2009
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    The circuit will be doing either Class A, Class AB or Class D audio amplification. Read up on those.
     
  17. bertus

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    Last edited: Dec 31, 2011
  18. sakuragurl

    Thread Starter Member

    Sep 27, 2008
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    okay....thank you so much for your help!!! I really appreciate it!!:)
     
  19. sakuragurl

    Thread Starter Member

    Sep 27, 2008
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    oh yeah....i would like to understand about how do we know which capacitor values are to be used? and if different values of capacitors are used...how does it affect the circuit? from what i know, capacitors main function is to filter DC and to allow AC to pass through besides helping to amplify the output voltage...
     
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