Chpt 6 - class b audio amp - help

Discussion in 'The Projects Forum' started by Alexander Dumas, Oct 16, 2007.

  1. Alexander Dumas

    Thread Starter New Member

    Oct 16, 2007
    5
    0
    Hi... I came across your site / example for building a class b audio amplifier.

    I don't have (6) 6v batteries... Can I use a single 12v battery? If so, can you tell me what modifications i would have to make to have it work?

    I am particularly interested in this circuit because I bought a cheap head-phone FM radio and want to output the audio through this amp...

    Lastly, it the output noticeable (e.g., loud) - or just so-so...
     
  2. cumesoftware

    Senior Member

    Apr 27, 2007
    1,330
    10
    You can use a 12V battery and a LM7806 voltage regulator. Apart from a 0.1uF tantalum capacitor at the output (as recommended in the datasheet), you don't need to use more components.
     
  3. thingmaker3

    Retired Moderator

    May 16, 2005
    5,072
    6
    Take the "ground" from the LM7806 output, and use take the "-6V" from battery negative.
     
  4. Alexander Dumas

    Thread Starter New Member

    Oct 16, 2007
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    0
    Ok... But just to clarrify - why the voltage regulator?

    I initially put (+) to 8, (+) to 5, and (-) to 4... Is that right?

    Lastly, I am particularly concerned if the output will be LOUD - easily heard across the room - right?

    If not, how do I boost the output?
     
  5. thingmaker3

    Retired Moderator

    May 16, 2005
    5,072
    6
    Pin 5 of the chip, the non-inverting i/p of amp B, must be connected to ground, not +. Ground is established by the voltage regulator.

    It would, of course, be easier to use two batteries as suggested in the text.
     
  6. Alexander Dumas

    Thread Starter New Member

    Oct 16, 2007
    5
    0
    Ok... I'll try it out...
     
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