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Damaged resistors

Discussion in 'General Electronics Chat' started by Scarr, Nov 30, 2017.

  1. Scarr

    Scarr Member

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    Hi All,

    I am being told be a supplier that standard UK mains spike could damage the resistors in this circuit. Can you take a look at this circuit diagram and answer the following questions

    A:Would would be the voltage required to damaged R36 & R47
    B:In your opinion would this be possible with standard UK mains


    Thanks

    Steve
     

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  2. Colin

    Colin Member

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    1u gives 70mA in full wave. You have 2 in series = 35mA 35mA through 180R = 250mW
    Voltage to damage would be 1kv
     
  3. Scarr

    Scarr Member

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    Hi Colin,

    Thanks for the reply, what does the 1u mean? <- Ignore this I was being stupid :)

    Steve
     
  4. dave

    Dave New Member

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  5. dknguyen

    dknguyen Well-Known Member

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    C39 and C42. They are labelled as 1u on your schematic rather than 1uF.
     
  6. audioguru

    audioguru Well-Known Member Most Helpful Member

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    In addition to a fairly long duration high current damaging a resistor, a short duration voltage spike can also damage a resistor by its arc. The resistor might be rated at only 300V when the normal peak voltage of 240VAC is 340V and a spike will be much higher.
     

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