a little help with capacitive power supply values


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    Default cap value

    the capacitor reactance (resistance for ac voltage) is
    1/(2 X pi X freq X Cap(micro-farad)) ohms,

    for 50MA from power supply, 220V/.050 = 4400 ohms....
    the required resistance provided by cap for 50HZ at 220V.

    then,
    Cap= 1/(314 X 4400) equal aprox .7 micro-farad cap (>250 VAC rated)
    works out to about .15 micro-farad per 10MA.
    See attached diag.
    Attached Images Attached Images  
    Last edited by amgen; - 30th December 2009 at 00:52.

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