[HELP] Laptop Speaker Design

Discussion in 'The Projects Forum' started by renotenz, Nov 18, 2010.

  1. renotenz

    Thread Starter New Member

    Oct 25, 2010
    11
    0
    Hi all! Currently I'm trying to make a laptop speaker on my own. I've search through this forum but haven't found any simple explanations on how to make it (my bad...)

    So I found this circuit which I've added to the attachment, credits to www.techlib.com

    Then I've tried to simulate it on EWB, but due to uncomplete library, I've had no use of the TIP32 PNP Transistor, instead I used TIP30C PNP. I've added a Ground on the downmost node since it won't simulate if I didn't give one.

    My question is why the output on 8 ohms resistor (substitute for the speaker) is only about 3 V rms on 100% Potentiometer value, as you can see at the other attachment. I used AC Voltmeter to measure it.

    I used 5 V AC input which RMS value is 3,5 V. Is 5V AC a common input from sound card for an external speaker?

    I've also test 1 V AC as the input, and the output is also about 3 V RMS on the 8 ohms resistor...
     
  2. JoeJester

    AAC Fanatic!

    Apr 26, 2005
    3,373
    1,157
    hook an oscilloscope in lieu of the meter and see the output.

    sound cards typically drive headphones. lower your input voltage until the oscilloscope shows no distortion.
     
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