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Full Wave Rectifier

Discussion in 'General Electronics Discussion' started by Nael, Mar 25, 2018.

  1. Nael

    Nael

    17
    1
    Oct 12, 2016
    Hello guys,

    I have question, I attach schematic of a full wave rectifier (each half wave schem).

    Notice the current flow arrow. That confuses me really.

    Would anyone explain the current flow and direction from the transformer to the load and going back! Try make it in simple words, such as Transformer to diode to etc.

    Thank you,
     

    Attached Files:

  2. Harald Kapp

    Harald Kapp Moderator Moderator

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    Nov 17, 2011
    The arrow indicates the electron flow, whereas the so called "technical direction of current" (which is commonly used) is from plus to minus.
    The current as shown in the original diagram would have a negative sign.
    I indicated the current flow during the two half waves of the sine in red whereas the blue lines indicate where no current can flow due to the diodes blocking.
     
  3. Nael

    Nael

    17
    1
    Oct 12, 2016
    Are you supposed to attach any photo!! I don't see where is the blue and red indication you talk about!
     
    davenn likes this.
  4. Bluejets

    Bluejets

    3,453
    698
    Oct 5, 2014
    During the first half cycle, current flows upwards in the transformer, through diode D1, through inductor LF and down through load RL, through the ground connection and back through the transformer centre tap.
    On the second or negative half cycle, current flows down through the transformer, through D2 , up through inductor LF once again and down through the load RL , back once again to the centre tap.
    Hence the current flow through the load is always in the same direction.
     
  5. Audioguru

    Audioguru

    2,573
    581
    Sep 24, 2016
    The drawing shows voltage polarities. Electrons flow from negative to positive.
    A diode conducts when its anode is positive and its cathode is negative. When the polarity across the diode is reversed then it does not conduct.
     

    Attached Files:

  6. Nael

    Nael

    17
    1
    Oct 12, 2016
    Thank you, but if the current goes through inductor to Load, why the current flow shows otherwise (opposite) on schematic!!
     
  7. Nael

    Nael

    17
    1
    Oct 12, 2016
    Thank you really for taking time on schematic, my question, isn't the flow supposed to go from inductor to load! why the electrons flow the opposite way on schematic!!
     
  8. davenn

    davenn Moderator

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    Sep 5, 2009

    don't get stressed out about the difference between conventional current flow ( + to -) and electron flow (- to +)
    it's not going to make any difference which you use in most circuits, including the one you are looking at
     
  9. Nael

    Nael

    17
    1
    Oct 12, 2016
    Exactly that's what drives me crazy, one schematic I read is in conventional flow and the other is (-to+) don't know how to trace anymore lol
     
  10. Bluejets

    Bluejets

    3,453
    698
    Oct 5, 2014
    Don't fuss over it, just accept it.
    Wait until you start with transistor theory and the movement of electrons one way or holes in the opposite direction.
     
    davenn likes this.
  11. Ratch

    Ratch

    1,042
    306
    Mar 10, 2013
    Another example of how technical slang can confuse and bemuse folks. Current flow means "charge flow flow", which is redundant and ridiculous. Current already means charge flow, so you don't have to say it twice. You should instead say current exists, or current is present, or just plainly say current.

    You will really meet yourself coming and going if you worry about the polarity of the charge carriers. Don't do that. Always use the mathematical convention, which is that current leaves the positive terminal of a voltage/current source and enters the negative terminal of the same source. Do all your calculations using that rule. Then, if you really need to know the direction of the charge carriers, reverse the calculated direction for negative carriers and keep the direction for positive carriers. Some conduction paths, like electrolytic reactions have negative electrons going one way and positive ions going the opposite direction. Diodes have electrons and holes going the opposite directions. Just use the mathematical convention and you won't get wrapped around the axle. Notice also that ammeters and semiconductor products like diodes are marked according to the mathematical convention.

    The current direction of the attachment you presented is wrong. If you inserted a ammeter in series with the load resistor, it will indicate that the mathematical current direction is from top to bottom. No wonder you are confused.

    Ratch
     
    bushtech likes this.
  12. Audioguru

    Audioguru

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    581
    Sep 24, 2016
    That is why I never look at "direction of current flow". Instead I simply look at the polarities.

    A diode has an arrow, a transistor emitter also has an arrow. The arrow is pointing at the negative wire when the diode or base-emitter junction conducts with forward current (a zener diode is used with reverse polarity).
     
  13. Harald Kapp

    Harald Kapp Moderator Moderator

    9,230
    1,861
    Nov 17, 2011
    I'm sorry, the image got lost in translation :D
    Here you are, see attachment
     

    Attached Files:

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    Last edited: Mar 26, 2018
    chopnhack and Cannonball like this.
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