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What is a coupling capacitor?

Discussion in 'Electrical | Electronics | Communications' started by kran, Dec 1, 2008.

  1. kran

    kran Newbie

    Hello all , I want to know what is meant by a coupling capacitor? I googled up to find that In analog circuits, a coupling capacitor is used to connect two circuits such that only the AC signal from the first circuit can pass through to the next while DC is blocked. Can someone here explain this in detail? Please help.
  2. silverscorpion

    silverscorpion Ace

    Engineering Discipline:
    Electronics & Telecommunications
    A coupling capacitor is a capacitor used to separate the various stages in a circuit, for example, to separate the stages of a multistaged amplifier. It separates the dc and ac components and 'couples' the output of one stage to the input of the next stage.
  3. sauravgoswami

    sauravgoswami Rookie

    Engineering Discipline:
    Electrical & Electronics
    watever silver said is correct,but the basic function of coupling capacitors is too remove noise or other disturbances and make sure the output of previous stage is compatible with one were it is inputted!!!
  4. hi, coupling capacitors are used in circuits to filter noise signals from passing on to the next stage. for example, a coupling capacitor is used in the input of an R-C coupled amplifier to filter dc noise. As u may know, the reactance offered by a capacitor Xc= 1/(2*pi*f*C) where f is freuency, c is capacitance. as d.c has 0 freq, so the reactance offered to dc by a capacitor is very very large.:smile:
  5. r6rammy

    r6rammy Newbie

    do i use it for adding dc to an ac signal???
    I am planning to do differential conductance measurement and i need to add the sine out from the lock in amplifier to a dc sourcemeter, how do i go about adding both together? Just join them????
  6. me_crazy

    me_crazy Newbie

  7. augustin87r

    augustin87r Certified CEan

    Engineering Discipline:
    Aerospace
    Hello,

    I have going through theoretic details about coupling capacitance. I have to exercise somehow. On this schematic, what are the coupling capacitors? I know a few , especially the electrolitic ones, but can somebody tell me all of them so that i can check my guesses...BEst regards, Augustin

    [​IMG]

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    the picture is larger on the host site
  8. akshay04907

    akshay04907 Certified CEan

    Engineering Discipline:
    Electronics & Telecommunications
    but sharat why it is necessary to block the dc component?why they r source of noise only?
  9. cranky

    cranky Certified CEan

    Engineering Discipline:
    Electronics
    hey i guess the noise here refers to the dc component silver mentioned
  10. cranky

    cranky Certified CEan

    Engineering Discipline:
    Electronics
    It becomes necessary to block dc components cause-for one,you want your signal with zero as reference,as in no offset...secondly,you do analysis about the operating point and hence,you don't want to disturb the bias

    * if Someone could say if this is right
  11. shreyasm89

    shreyasm89 Certified CEan

    Engineering Discipline:
    Electronics & Telecommunications
    you are absolutely right
  12. cranky

    cranky Certified CEan

    Engineering Discipline:
    Electronics
    @shreyas89:thumbs up :)
  13. Bags003

    Bags003 Certified CEan

    Engineering Discipline:
    Electronics & Telecommunications
    It helps to isolate the DC bias settings of the two coupled circuits.
  14. electronics12

    electronics12 Certified CEan

    Engineering Discipline:
    Electrical & Electronics
    A coupling capacitor is a capacitor that allows AC signals to go through but not DC. DC signals are blocked. This is useful for many applications such as when biasing microphones. The DC is needed just for power but should not be transferred to the second half of the circuit.

    A good article for reference on coupling capacitors is:
    http://www.learningaboutelectronics.com/Articles/What-is-a-coupling-capacitor
  15. larry80

    larry80 Newbie

    Engineering Discipline:
    Ceramic
  16. naveee

    naveee Apprentice

    Engineering Discipline:
    Electrical & Electronics
    if both AC an DC are separated wat component will through the remaining circuit ?????
  17. Jeffrey Samuel

    Jeffrey Samuel Star

    Engineering Discipline:
    Electronics
    not possible to add a DC signal to AC signal using a coupling capacitor it prevents the DC component completely and passes the AC component furthur
  18. Jeffrey Samuel

    Jeffrey Samuel Star

    Engineering Discipline:
    Electronics
    my post #17 answers your qn also i guess
    • Like Like x 1
  19. Jeffrey Samuel

    Jeffrey Samuel Star

    Engineering Discipline:
    Electronics

    dc component is not the only source of noise any where

    in multi stage if DC passes further there is a possibility of shifting the bias and also to cause signal loss

    this can be avoided if we use a coupling capacitor
  20. naman2511

    naman2511 Apprentice

    Engineering Discipline:
    Electrical & Electronics
    a simple capacitor can do blocking of dc...then whats is the need of coupling capacitor??

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