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Audio Amplifier Design

Discussion in 'Audio' started by Samson Jabu Masemola, May 16, 2015.

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  1. Samson Jabu Masemola

    Samson Jabu Masemola

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    Feb 11, 2015
    Hi everyone

    I would like to ask some help on an Audio amplifier. My load is 8Ohm. and to my calculations using TIP31C/TIP32 and with each having a VCE(SAT)=1.8V I got to my output power being Pout approaximately 8W (5.65W RMS). I managed to simulate the circuit atached and alreadty I burned R7. Help with what is the wrong this I am doing.

    circuit.jpg

    Regards
    Samson
     
    Last edited by a moderator: May 16, 2015
  2. Arouse1973

    Arouse1973 Adam

    5,164
    1,080
    Dec 18, 2013
    What wattage resistor is R7? You also need some bias for your VA stage.
    Thanks
    Adam
     
    Last edited: May 16, 2015
  3. Samson Jabu Masemola

    Samson Jabu Masemola

    6
    0
    Feb 11, 2015
    Thanks.
    For R7 I used 0.25W, But thanks I noticed that the current that was flowing through this resitor is too much. By VA you mean the amplifiying stage?
     
  4. Arouse1973

    Arouse1973 Adam

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    Dec 18, 2013
    Yes voltage amplification stage.
     
  5. Samson Jabu Masemola

    Samson Jabu Masemola

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    0
    Feb 11, 2015
    Thanks. Now if I want to put a volume control circuit and achieve the 300-3400Hz frequency sweep. Can you please advice me on that.
     
  6. Arouse1973

    Arouse1973 Adam

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    Dec 18, 2013
    You can't change the frequency buy adjusting the volume.
    Adam
     
  7. Samson Jabu Masemola

    Samson Jabu Masemola

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    0
    Feb 11, 2015
    Thanks. I am aware of that. I know I have to use capacitors (I.e. coupling, bypasss and decoupling) to determine the frequency sweep. What I'm asking is the Volume control, where to put it in my circuit and how to configure it.

    I have attached my latest circuit using Diff Amp and power stages, I tested it using 2N2905/2N3085 and only the NPN transitor draws about 350mA while the PNP draws 30mA. And my output signal is oscillating around 0.7Vdc. Do you know what could be the issue here?
     

    Attached Files:

  8. Arouse1973

    Arouse1973 Adam

    5,164
    1,080
    Dec 18, 2013
    Here is a simple amplifier circuit. The input is 200 mV sine wave @ 1KHz. The output is approx. 10 V Pk-Pk into an 8 Ohm load. See if you can see what might be wrong with yours. This amplifier is not ideal but I have tried to keep it as close to what you have done.
    Adam

    AMP.PNG
     
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