Audio amplifier (BJT) using BC182BP

Discussion in 'The Projects Forum' started by vibz90, Nov 1, 2009.

  1. vibz90

    Thread Starter New Member

    Oct 24, 2009
    I have to build a BJT amplifier using BC182BP transistor, to amplify the sound of DOM5242L_R (the mic to be used) to be fed in a normal pc.
    The resistors and the capacitors of the amplifier should be based on the gain depending upon the values of mic and the input value of the sound card (or any such thing in pc).
    I have found the basic circuit .The output will be connected through a 3.5mm jack and the input voltage is supplied from the mic, i just need to know the gain and the value of resistors and capacitors accordingly....
    i have attached my circuit with this file.
  2. hgmjr


    Jan 28, 2005
    I noticed you posted this same question in the Homework forum. Which one of these forums do you need it to be in?

  3. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
    A sound card "Line In" input expects a signal around 1V-1.5V peak to peak max, some are more forgiving than others, so error on the side of caution.

    A dynamic microphone gives and output between 1mV-15mV

    Typical input impedance of the "Line In" jack on a sound card is 600 Ohms.

    A clean Class A amp with a compensated/fixed gain of 100 would do the trick.
  4. vibz90

    Thread Starter New Member

    Oct 24, 2009
    i need it in the projects forum
  5. vibz90

    Thread Starter New Member

    Oct 24, 2009
    thanks thatoneguy.

    My microphone is an ECM, i hope it is the same as dynamic microphone.
    So, what values should i change in my resistors and capacitors in circuit (attached image) to get this gain. And I am still not sure whether my circuit is the right one or not, so plz check it and tell me if anything needs to be changed.
    One more thing, my teacher said something about using a potential divider to get the 1.5 voltage. Is it necessary? How will that be done?

    Thanks again