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A simple amplifier

Discussion in 'The Projects Forum' started by zogorean, Oct 15, 2013.

  1. zogorean

    Thread Starter New Member

    Jan 12, 2013
    Hello all.

    I am trying to make a simple amplifier Circuit, and I just can't get it right.
    Here is what I'm trying to do:

    I have a program on my laptop that can generate signals (sine waves, squire waves, noise etc). I would like to connect the output from my laptop (speaker out - Jack stick) to a Circuit, which has a 24v power supply, and boost the signal from the laptop in such way, that the amplitude of the output is 24v or close to that. Also the amp should be able to handle squire waves, sine waves etc.

    I've modeled many Circuits (Class AB amplifiers and similar) on LT Spice, but it seems that the output amplitude never dives below 0v and always stays above. I've also though about using opto amps like the 4580, but a simple transistor Circuit just seems better, or am I wrong?

    Basically if I have a +/- 3v output amplitude from my laptop, I would like to feed the signal to an amp, that generates a +/- 24v amplitude of the same signal. Also should I use special components if the output signal frequency is 20KHz or above?

    Many thanks in advance.
  2. eman12

    Active Member

    Oct 26, 2007

    You must give more info about the output of the amplifier you want to make (including the output wattage) and your goal.
    So you say you want to have 20kHz and above on the output or not? If you want those signals then I suggest using an op-amp or an power op-amp as the amplifier...
  3. #12


    Nov 30, 2010
    A, "simple" transistor circuit struggles to accomplish what an op-amp does with ease.
  4. shteii01

    AAC Fanatic!

    Feb 19, 2010
    If you want to see positive peaks and negative peaks, you need +24V supply for the positive supply input of the op-amp, and you need -24V supply for the negative supply input of the op-amp.

    However, if you do +24V and -24V, your range from peak to peak will be 48V. If you want peak to peak to be 24V, you will want +12V supply and -12V supply for the op-amp.
  5. zogorean

    Thread Starter New Member

    Jan 12, 2013
    Hi all.

    Thank you very much for your input. It does sound like I should use an op-amp instead.

    I was under the impression that I could create a "simple" enough Circuit, that took the output from my soundcard as input and had a 24v power supply, and somehow boosted my signal to 48v peek-to-peek. The wattage I believe would depend on the power supply.

    To tell you the background, I would like to play with some transformers, to better understand the functionality of transformers, and how they react under load, pulsing them with different waveforms and frequencies.

    But as far I understand from your posts, an op-amp is the better choice.

    Thanks Again to all for taking your time to explain.
  6. wayneh


    Sep 9, 2010
    +1 to that, but what power output do you need? Op-amps don't get you into the higher power range. For 100W per channel hi-fi, you still need big transistors.
  7. bertus


    Apr 5, 2008