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Lets take a look at a linear amplifier

Discussion in 'Electronics Homework Help' started by Hasan2019, Sep 11, 2019.

  1. Hasan2019

    Hasan2019

    9
    0
    Sep 11, 2019
    Hi there,

    Hope my post find you well.
    I like to get attention the knowledgeble person in this post !
    So, kindly avoid this post if you wont have experience.

    I wanna post a circuit that may be explained by Dr. Kolar, a famous Swiss or Austrian proffesor.

    I need to know this application well, because I want to develope a 3-phase-calibrator.
    My application needs to amplify signal to a certain level. Class D switching is necessary!

    Here we go ....
    Explain kindly
    linear_amp.PNG
    1. Why we need to think SNR for this case?
    2. Why we need to think frequency gain voltage booster? Loop gain!
    3. Explain impedences, transcondactance etc for whole circuit.
    4. How the voltage and current is being controlled here?


    Thanks a lot!
     
  2. Harald Kapp

    Harald Kapp Moderator Moderator

    9,380
    1,912
    Nov 17, 2011
    Have you done any research at all into these question by yourself?
    These are fundamental questions. You need to study the matter in detail. There are no quick and easy answers.

    Why not look on the website where you found this circuit?
     
    Hasan2019 likes this.
  3. Hasan2019

    Hasan2019

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    0
    Sep 11, 2019
    Thank you Mr. Kapp.
    Actually I have a productive design similar to this circuit.

    If you can make some comment on it, then I could get a way to start.
     
  4. Audioguru

    Audioguru

    2,618
    593
    Sep 24, 2016
    The schematic you posted is class-AB and it wastes a lot of power making heat. A class-D amplifier is completely different.
    You did not say the frequencies or load impedance.
     
    Hasan2019 likes this.
  5. Hasan2019

    Hasan2019

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    Sep 11, 2019

    After a long discussion its assumed that " SMPS/ bridge type power amplifier switching topologies can be applicable"
     
  6. Audioguru

    Audioguru

    2,618
    593
    Sep 24, 2016
    Maybe the thing you want to make does not use an audio power amplifier.
     
    Hasan2019 likes this.
  7. davenn

    davenn Moderator

    13,329
    1,769
    Sep 5, 2009

    and that has nothing to do with your OP

    and you didn't answer @Audioguru 's questions
     
  8. Hasan2019

    Hasan2019

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    Sep 11, 2019
    May be or may not be ! Linearity is MUST. TIP142, TIP 147 were used before ,https://www.onsemi.com/pub/Collateral/TIP140-D.PDF .
    As you have suggested before, for CT a high current classD can be used.
     
  9. WHONOES

    WHONOES

    731
    150
    May 20, 2017
    Looking at you amplifier schematic, it is overly complicated. Much simpler solutions are available. Also, if you plan to use + and - 90V as indicated on your diagram, the TIP142 and 147 combination will not be suitable as they are only rated to 100V.
     
  10. Hasan2019

    Hasan2019

    9
    0
    Sep 11, 2019
    Nice comment !
    From your huge experience and experties, could you suggest me any ClassD amplifier that could be used in 60Hz transformer. Take a look the requirments

    1. 7 V ac, 60 Hz input, audio range ( PWM possible).
    2. Supply voltage should be + & - 24 v.
    3. 7.5 ohm load.
    4. Output should be 15V/ 2 A. 30-35 Watt.
    5. SC protection and current sensing capabilities.
    6. Step up potential transformer(180-380V/ 0.166A) application.
     
  11. WHONOES

    WHONOES

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    May 20, 2017
    Hasan2019 likes this.
  12. Hasan2019

    Hasan2019

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    Sep 11, 2019
    Similar to you, I have already read this thread 3 weeks ago. Do you think, according to my requirement its 100% full matched?

    Why dont you explain more about.....
    1. Core saturation
    2. Residual flux exists in core
    3. DC offset near transformer load
    4. LC filter missmatched
    5. Transformer negative feedback connection
    6. Phase shift caused.
     
  13. WHONOES

    WHONOES

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    150
    May 20, 2017
    Hasan2019 likes this.
  14. Hasan2019

    Hasan2019

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    Sep 11, 2019
    You are knowledgeble for sure.
    Your long paragraph says an important lesseon,
    "If a transformers primary winding was connected to a DC supply, the inductive reactance of the winding would be zero as DC has no frequency, so the effective impedance of the winding will therefore be very low and equal only to the resistance of the copper used. Thus the winding will draw a very high current from the DC supply causing it to overheat and eventually burn out, because as we know I = V/R "
     
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