How to size a capacitor?

Discussion in 'Electronics & Electrics' started by Supremo, Sep 18, 2006.

  1. dakiller

    dakiller (Oscillating & Impeding)

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    I think you've got a bit confused with the equation here, its -t/(R*ln(Vt/Vo)), I guess I didn't make it that clear

    And LOGe is log to the base e and on most calculators it is the ln() button where as the log() button is log to the base 10

    A good simple way to think about what a capacitor looks like in a circuit, is that is is a 'resistor' that changes value depending on the frequency it sees, where DC it is infinite, and it approaches 0ohm as the frequency tends towards infinite. So in a DC circuit, any AC ripple on top of the DC signal is 'shunted through' the capacitor where the amount that is is shunted is dependent on the 'resistance' of the cap which is dependent on the frequency of the AC (thats why I said that caps only work on AC above)
     

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