resistor calculation.

Discussion in 'General Electronics Chat' started by RRITESH KAKKAR, Sep 19, 2015.

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  1. RRITESH KAKKAR

    Thread Starter Senior Member

    Jun 29, 2010
    2,831
    89
    Hello,
    I am trying to find the series resistor for custom led on main?
    see if there is 220V ac i convert to c with bridges rectifier it will be 220xsqroot 2= 311v so, for 1.7v led 331-1.7=309v
    for 20mA it will be 15.47k is thi right?
     
  2. bertus

    Administrator

    Apr 5, 2008
    15,638
    2,344
    Hello,

    We still do not allow leds DIRECTLY connected to the mains.

    Bertus
     
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