Question about capacitors ?!

Discussion in 'General Electronics Chat' started by greenpeace, Nov 20, 2007.

  1. greenpeace

    Thread Starter Active Member

    Sep 22, 2007
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    hello everybody ,

    before I introduce the problem , I have to tell you that I'm not an electrical engineer ,
    but I have a problem related to your major & I hope someone can help me !

    suppose that we have to insert a capacitor in a circuit

    but for that capacitor = instead of consisting of to adjacent plates

    it consists of many plates ( say 8 or 10 or any other )

    ( I don't know if it is called multi-capacitor or not :confused: )
    The question is / how these plates will be connected ?
    & what is the benefits of using many several plates instead of just 2 ?


    hope someone can help me & give me as more information as possible [​IMG]
     
  2. Gadget

    Distinguished Member

    Jan 10, 2006
    613
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    -|-|-|-|-|-|-|-|-|-|----------- terminal 1
    --|-|-|-|-|-|-|-|-|-|---------- terminal 2

    By interleaving the plates a greater plate surface area is achieved in a small space meaning more capacitance. Commonly seen in Tuning gangs.
     
  3. greenpeace

    Thread Starter Active Member

    Sep 22, 2007
    30
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    thanks < Mr . Gadget :)

    but can you explain how the plates are connected more please :(

    ( keep in mind that my knowledge in this field is very poor )

    I'm mechanical engineer :D

    just explain it in words
    & if you can / explain that illustration about terminals !
     
  4. Papabravo

    Expert

    Feb 24, 2006
    10,138
    1,789
    The metalic plates are soldered or welded to a metalic conductor. One set of plates is connected to one of the two terminals. The other set of plates is connected to the other set of terminals. In this configuration there is no way for a DC current to flow. Only an AC current can flow through a capacitor. That concept may be beyond your understanding at the moment, but you can take it on faith for the time being until you have a chance to investigate the matter further.
     
  5. greenpeace

    Thread Starter Active Member

    Sep 22, 2007
    30
    0

    I didn't understand how each plate is connected to the plate next to it ??
     
  6. greenpeace

    Thread Starter Active Member

    Sep 22, 2007
    30
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    I will try to illustrate my imagination of that capacitor
    and you tell me which configuration is the right one !
     
  7. greenpeace

    Thread Starter Active Member

    Sep 22, 2007
    30
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    if this configuration is considered , what is the answer to that question ?
     
  8. greenpeace

    Thread Starter Active Member

    Sep 22, 2007
    30
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    here is illustrated question :D :
     
  9. greenpeace

    Thread Starter Active Member

    Sep 22, 2007
    30
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    here is illustrated question about the charge :
     
  10. greenpeace

    Thread Starter Active Member

    Sep 22, 2007
    30
    0
    I want your answers to consider :

    * the way of connecting each plate to the plate next to it .

    * charge distribution in the plates .

    * the separation between the plates ( whether the plates are equally separated , or there is separation between two sets of plates < beside the separation between each plate > )
     
  11. greenpeace

    Thread Starter Active Member

    Sep 22, 2007
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    waiting for your answers :(
     
  12. thingmaker3

    Retired Moderator

    May 16, 2005
    5,072
    6
    My major was Theater Arts, but I'll answer your question anyway.;)

    Your drawings are capacitances in series. They are solved using 1/C1 + 1/C2 + 1/C3... + 1/Cn = 1/Ct where Ct is the equivalent capacitance. Ergo, if you have eight plates instead of two, and they are all the same size and same distance apart with the same dielectric, you have 1/8 the Farads you would have with a "normal" capacitor of the same specification.

    There is no reason to do this, of course. Much less costly would be to simply make a smaller capacitor.
     
  13. greenpeace

    Thread Starter Active Member

    Sep 22, 2007
    30
    0
    nice to shear knowledge :)

    by this configuration we increase the cross-sectional area
    and therfore increasing the capacitance .

    but the problem is , how each plate is connected to the plate next to it ?
    and what about the charge ditribution in each plate ?
     
  14. thingmaker3

    Retired Moderator

    May 16, 2005
    5,072
    6
    I've often been accused of "cutting up.":D

    Such is not what your drawings show. Was this your intent? To show what others in this thread have described? The scheme in your drawings decreases capacitance.

    By any method cost-effective to the manufacturer. The plates would not be connected to the next plate, though, rather to the one beyond. See the "variable tuning capacitor" in this reference: http://encyclopedia2.thefreedictionary.com/capacitor
    Even, equal, and pretty much uniform.
     
  15. greenpeace

    Thread Starter Active Member

    Sep 22, 2007
    30
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    I told you before that i cannot imagine its shape
    that's why i draw it , so you can tell me if I'm right or wrong :D


    thanks alot for the link

    see the attachement and answer my question :)
     
  16. thingmaker3

    Retired Moderator

    May 16, 2005
    5,072
    6
    The gray plates are connected electrically as one plate. The white plates are connected electrically as the other plate. When the gray plates rotate into the spaces between the white plates, capacitance is increased.
     
  17. greenpeace

    Thread Starter Active Member

    Sep 22, 2007
    30
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    can this be done without rotation ?

    I mean is there any type of capacitors with many plates
    where the two sets are stationary ?
     
  18. thingmaker3

    Retired Moderator

    May 16, 2005
    5,072
    6
    They're not "many plates." They're "many sections of the same plate."
     
  19. greenpeace

    Thread Starter Active Member

    Sep 22, 2007
    30
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    so the vertical plates are sections of the horizontal plate ?
     
  20. greenpeace

    Thread Starter Active Member

    Sep 22, 2007
    30
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    see what the doctor draw :confused:
     
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