Intercom

Discussion in 'Homework Help' started by 12u9s, Jul 6, 2011.

  1. 12u9s

    Thread Starter New Member

    Jul 6, 2011
    3
    0
    Hello, I am new to the forum, great site indeed. I have trouble understanding the function of transistors in this circuit (link)
    I know they are amplifying the signal from the microphone but do not understand how, that connection, especially that of the first transistor is a project of electronica, thanks for the help, when I know how it works at all lay it on my site, I if this is not allowed to post the link here, thanks for the help. and sorry for the bad English I'm just learning
     
  2. Robert.Adams

    Active Member

    Feb 16, 2010
    112
    5
    You forgot to actually make the link. Please provide a link to the schematic if you actually want to get helped.
     
  3. 12u9s

    Thread Starter New Member

    Jul 6, 2011
    3
    0
    Certainly this is the link http://www.zen22142.zen.co.uk/Circuits/Misc/intercom.htm
    talk to my teacher and told me that the feedback is part of a more advanced course, then I must consider the resistance of 56K as an open circuit, which simplifies the analysis, however I wonder how it affects overall performance in eliminate the feedback circuit. thanks
     
  4. Robert.Adams

    Active Member

    Feb 16, 2010
    112
    5
    The transistor part of the circuit forms the pre-amplifier block. This is a good resource on preamplifier design with transistors: http://www.rason.org/Projects/bipolamp/bipolamp.htm

    The design given is slightly different but the concept is essentially the same.

    If you have any further questions about the transistor function, feel free to post back with them. Perhaps someone else can help clarify the role of the feedback path, I'm not too good with that.
     
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