Pure class B amp help

Discussion in 'The Projects Forum' started by CRY&PRAY, Feb 8, 2014.

  1. CRY&PRAY

    Thread Starter Member

    Jan 6, 2014
    84
    0
    hello guys :) i've built this simple amp, it consist in a lm358n driving a pure class B push-pull and it's getting a negative feedback by a 220Ω resistor, the question is: is it scalable to high power?

    currently is running from a 5 v battery pack (2.5v ±), in the schematic i've put a 5v regulated (positive and negative) supply for the lm358n and i've increased the voltage to the push pull, but still there is a problem, the feedback get's higher, so i have to increase the resistor (and of course put more power transistor)

    if i do all that things will it increase the output power? and any ideas on how to stabilize it, cuz sometimes when i plug it in on my mp3 it sounds bad and i have to short the input with the ground and plug back in the mp3 and the works fine, it's like a "reset", a thing that i want to get rid off.

    -Francesco
     
  2. donpetru

    Active Member

    Nov 14, 2008
    186
    25
    Please, post schematics in PDF or JPG format.
     
  3. Experimentonomen

    Member

    Feb 16, 2011
    331
    46
    NO! This is not scalable for higher power.

    If you want more power than just a watt or two, go buy a LM3886 kit, that gives you 60 watts in 4 ohms which is plenty.
     
  4. bertus

    Administrator

    Apr 5, 2008
    15,646
    2,345
    Hello,

    There are a couple of nice audio amplifier projects in "the completed projects" forum.
    Take a look in it's index:
    Completed Projects Index

    Bertus
     
  5. CRY&PRAY

    Thread Starter Member

    Jan 6, 2014
    84
    0
    i've attached the amp that i made to a 18v ± and it gives out more power, i'll try a darlington pair to archive more gain, beacause that poor lm358n is driving directly 2 power transistors (d688 and d718)
     
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