<P> Various properties of ripple voltage may be important depending on application: the equation of the ripple for Fourier analysis to determine the constituent harmonics; the peak (usually peak - to - peak) value of the voltage; the root mean square (RMS) value of the voltage which is a component of power transmitted; the ripple factor γ, the ratio of RMS value to DC voltage output; the conversion ratio (also called the rectification ratio or "efficiency") η, the ratio of DC output power to AC input power; and form - factor, the ratio of the RMS value of the output voltage to the average value of the output voltage . Analogous ratios for output ripple current may also be computed . </P> <P> An electronic filter with high impedance at the ripple frequency may be used to reduce ripple voltage and increase or decrease DC output; such a filter is often called a smoothing filter . </P> <P> The initial step in AC to DC conversion is to send the AC current through a rectifier . The ripple voltage output is very large in this situation; the peak - to - peak ripple voltage is equal to the peak AC voltage minus the forward voltage of the rectifier diodes . In the case of a SS silicon diode, the forward voltage is 0.7 V; for vacuum tube rectifiers, forward voltage usually ranges between 25 and 67V (5R4). The output voltage is a sine wave with the negative half - cycles inverted . The equation is: </P> <Dl> <Dd> <Dl> <Dd> V L (t) = V A C p ⋅ s i n (t) (\ displaystyle V_ (\ mathrm (L)) (t) = V_ (\ mathrm (AC_ (p))) \ cdot sin (t)) </Dd> </Dl> </Dd> </Dl>

Peak to peak ripple voltage of half wave rectifier