Question Ccoming from CHINA

Discussion in 'General Electronics Chat' started by hetiandmeng017, Jan 10, 2013.

  1. hetiandmeng017

    Thread Starter New Member

    Jan 10, 2013
    8
    0
    hello everybody,
    Nice to see you all!
    It's very hard for me to have come here,because our government forbit us from visiting any foreign website at all.<<Prison Break>>victory!!

    My English is not good,but my question seems a little hard for Chinese netizen.
    So,I want to take a chance with you freinds.

    It's the question:
    I came across this so called output stage pic1
    [​IMG]
    (Excerpt from the datasheet of icl8038:a kind of waveform generator)
    then I realized this must be the so called "Complementary output circuit",
    QUESTION1:Am I right?

    However,my confusion is not over,here is why:
    [​IMG]
    [​IMG]


    as the pic2 picture,the standard "Complementary output circuit" should be like that,and its AC circuit(path) should be like pic3(the ac impedance of 2 diode could be ignored obviously ).
    in pic3 we can see ,the Positive and the negative half cycle of signal 's AC path is the same(wondering if you understand me much,lol),and it is certainly issential.

    QUESTION2:But as we can see,pic 1 obviously couldn't accord with this condition. anyone could help me?

    Thx a lot!
     
  2. PackratKing

    Well-Known Member

    Jul 13, 2008
    850
    215
    Hello ! And welcome to AAC... your schematic is a wee bit out of my amateur league, so welcome anyway... :D
     
    hetiandmeng017 likes this.
  3. ErnieM

    AAC Fanatic!

    Apr 24, 2011
    7,386
    1,605
    So glad you made it here, hope you don't have any trouble!

    The first amp is a type of complementary output stage, it is intended for a circuit that does not have a negative supply. It will source and sink current to about a diode drop from either rail.

    It may help to convert the transistors acting as diodes to diode symbols:

    [​IMG]
    When UI goes a diode drop above the output Q39 will conduct and supply current.

    When UI goes a diode drop below the output Q40 will conduct and sink current.

    Keeping a dead zone of the diode drop keeps both transistors from turning on at the same time.

    Sorry but I can't make a nice AC model like your third figure shows of the second figure.
     
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  4. hetiandmeng017

    Thread Starter New Member

    Jan 10, 2013
    8
    0
    thx alot for your answer!
    You are so intelligent,yes,it looks like you have the same thinking as I had before. but i still have another puzzle:
    The large signal model and small signal model ,which one of them should be used here in BJT Q38?
    in another way,the following pic is alright?
    [​IMG]
     
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  5. hetiandmeng017

    Thread Starter New Member

    Jan 10, 2013
    8
    0
    as the time difference ,right now you guys must be sleeping,have a nice dream!
    :)
     
  6. Artfldgr

    Active Member

    Aug 15, 2008
    44
    1
    Welcome!!!

    what a beatiful place hetian is...
    home of some of chinas best Jade
    hetian, and hotan jade... beautiful mutton fat white...

    sorry, off subject, but it is a wonderful thing... ;)
     
    hetiandmeng017 likes this.
  7. DerStrom8

    Well-Known Member

    Feb 20, 2011
    2,428
    1,328
    Welcome to AAC, hetiandmeng017! I am very glad you were able to make it here. By the way, your English is quite good. I hope you find the answers you're looking for. You're definitely talking to the right people! Unfortunately I generally do more work with digital circuits than with analog ones, but I wanted to bid you welcome and wish you the best of luck!

    Regards,
    Matt
     
    hetiandmeng017 likes this.
  8. hetiandmeng017

    Thread Starter New Member

    Jan 10, 2013
    8
    0
    thx Artfldgr ,


    It looks like you know hotan very much,did you ever come to China,or Hotan precisely.
    what a coincidence is,I was growing up in Hotan,and my chinese name is hetian(have the same pronounciation as the place Hotan).
    I also have several hotan jades too.Yeah,they are beautiful,and thx for you loving this place!

    Regards,
    Hotan
     
    Last edited: Jan 19, 2013
  9. hetiandmeng017

    Thread Starter New Member

    Jan 10, 2013
    8
    0
    thanks matt.thanks for your encouragement 。
    It's very good of you to say so.
    I will enjoy every moment here in Acc.


    Regards,
    Hotan
     
  10. hetiandmeng017

    Thread Starter New Member

    Jan 10, 2013
    8
    0
    still you didn't finish answering my question my friend ErnieM!
    regards,
    Hotan
     
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