Regulated DC supply - need help with calculations

Discussion in 'General Electronics Chat' started by ankit_mcgill, Mar 14, 2012.

  1. ankit_mcgill

    Thread Starter New Member

    Mar 14, 2012
    1
    0
    Hello All,

    I am in the process of making a regulated power supply to convert AC(220V, 60Hz) to DC(9V, 500ma). I have worked out all the calculations and would appreciate if someone could double check just to make sure they are alright.

    My setup is as follows

    AC(220,60Hz) -> Transformer(12V,500ma) -> Bridge Rectifier -> Voltage Regulator(7809)

    1. the 78xx series requires at least 2V to work => i need at least 11 as rectifier output

    2.the ac input might vary by 10% ..

    peak transformer voltage = 12 * 1.414 = 16.97V

    min transformer voltage = 16.97 - 1.697 = 15.27V

    vout-bridge = vmin-transformer - (2-0.7) - Vripple
    vripple = 15.27 - 1.4 - 11 = 2.87
    dt * load current / C = 2.87
    C = 8ms * 500mA / 2.87
    C = 1393 μf

    can someone confirm this is correct ??

    thank you for the help !

    ankit
     
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