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power amplifier

Discussion in 'General Electronics Discussion' started by ans, Nov 25, 2010.

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  1. ans

    ans

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    Nov 25, 2010
    The power amplifier works on the basic principle of converting the DC power drawn from the power supply into an AC voltage signal delivered to the load. Although the amplification is high the efficiency of the conversion from the DC power supply input to the AC voltage signal output is usually poor. The perfect or ideal amplifier would give us an efficiency rating of 100% or at least the power IN would be equal to the power OUT. However, this can never happen as some of its power is lost in the form of heat and also, the amplifier itself consumes power during the amplification process.
     
  2. barathbushan

    barathbushan

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    Sep 26, 2009


    Yes you are absolutely right , so what's the problem ??:)
     
  3. ans

    ans

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    Nov 25, 2010
    I want to know how it happens
     
  4. barathbushan

    barathbushan

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    Sep 26, 2009
    do you want to know why the efficiency is poor or how to increase efficiency ??
     
    Last edited: Nov 25, 2010
  5. ans

    ans

    19
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    Nov 25, 2010
    how to increase efficiency?
     
  6. barathbushan

    barathbushan

    223
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    Sep 26, 2009
    amplifiers are grouped into classes by their power efficiencies so pick yours from below ,
    google the circuit and use it !!

    1) class A amplifier - about 25 %(max) efficient - use this circuit if you dont care about power consumption , but you want a nice linear signal :) [output follows input faithfully !!]

    2)class B - it has a 50% operating cycle (means you get onle half a wave) , so you need two such amplifiers in "PUSH PULL CONFIGURATION" , but apart from cross over distortion (which can be taken care of) , the linearity is good , efficiency can go upto 78 % , this is the best if you ask me .

    3)class C - gives you upto 80~85% efficiency since the operating cycle is less than 50 % , use it if your need is communication

    4)class D - gives higher efficiency than class c , but used for digital applications .

    There are other classes too , but not widely used


    you see the efficiencies are fixed , meaning you cannot "INCREASE" them , as by nature there are things like leakage currents ,drop out voltages, heat dissipation, properties of semiconductor with respect to temperature , design aspects and other such factors .
    NO SYSTEM IS 100 % EFFICIENT !!! :)
     
    Last edited: Nov 25, 2010
  7. ans

    ans

    19
    0
    Nov 25, 2010
    thanks for reply.
     
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