Help needed : Difference bitween the two

Discussion in 'The Projects Forum' started by sakbd.2010, Dec 15, 2010.

  1. sakbd.2010

    Thread Starter Member

    Sep 19, 2010
    39
    0
    Hello,

    Trying to design a small unreg. power supply for my project. What is the difference in the two setups of the power supply ?

    Please see the attached image.

    What is the difference bitween the two unregulated supply ?. If 220vac varies from 170vac to 270vac will the output decrease and increase the same way for both, or there will be a difference in out put voltage and or current ?

    Pls. help understand the difference.
     
  2. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
    6,357
    718
    The top one has a better filtering arrangement, a side effect is that it is also current limiting.

    Neither one is regulated, so the higher the load, the lower the terminal voltage will be, with worse ripple.

    What is your load going to be? It is usually cheaper to get a wall wart Switch Mode Power Supply that does the AC-DC conversion at high frequency. These regulate very well and cost about the same as only the transformer for a linear supply.

    I can't say if the supplies you show would work for your application without knowing what the application is.
     
  3. sakbd.2010

    Thread Starter Member

    Sep 19, 2010
    39
    0
    Hi, thanks for your quick answer. this circuit shall be used as an input for a comparator sensor to detect whether the line voltage is within a set limit of 170vac to 270vac. If I use the First unreg. supply then, What is going to be DC voltage at output for 170vac input at the transformer ? What is going to be DC output for 270vac input, how to calculate this ? Line voltage is 220vac at 50 Hz, as shown in the first/2nd. circuit.
     
  4. blueroomelectronics

    AAC Fanatic!

    Jul 22, 2007
    1,758
    98
    Your transformers are connected wrong.
    [​IMG]
     
  5. sakbd.2010

    Thread Starter Member

    Sep 19, 2010
    39
    0
    Hi bill,

    Sorry...Not very good at drawing..., Also was very tired. I did connected them right, but here drawn the connections wrong.

    Here is updated image..hope got it right this time.
     
    Last edited: Dec 15, 2010
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