Editing Rectifier (section)

===Performance with low impedance source===
[[Image:Reservoircapidealised.gif]]

The above diagram shows the voltage waveforms of the reservoir performance when supplied from a voltage source with near zero [[Electrical impedance|impedance]], such as a mains supply.  Both voltages start from zero at time t=0 at the far left of the image, then the capacitor [[voltage]] follows the rectified AC voltage as it increases, the capacitor is charged and [[Electric current|current]] is supplied to the load. At the end of the mains quarter cycle, the capacitor is charged to the peak value Vp of the rectifier voltage. Following this, the rectifier input voltage starts to decrease to its minimum value Vmin as it enters the next quarter cycle.  This initiates the discharge of the capacitor through the load while the capacitor holds up the output voltage to the load.

The size of the capacitor C is determined by the amount of ripple r that can be tolerated, where r=(Vp-Vmin)/Vp.<ref>{{cite journal|last1=Cartwright|first1=Kenneth|last2=Kaminsky|first2=Edit|title=New equations for capacitance vs ripple in power supplies|journal=Latin American Journal of Physics Education|date=2017|volume=11|issue=1|pages=1301–01 1301–11|url=http://www.lajpe.org/mar17/1301_Kenneth_2017.pdf}}</ref>

These circuits are very frequently fed from [[transformer]]s, which may have significant [[Electrical impedance|internal impedance]] in the form of [[Electrical resistance|resistance]] and/or [[Electrical reactance|reactance]]. Transformer internal impedance modifies the reservoir capacitor waveform, changes the peak voltage, and introduces regulation issues.