In this case there are now 4 diodes and one AC voltage source. This connection of the 4 diodes is also known as a “Bridge Rectifier”. In this circuit there is NO inductor connected in series with the voltage source, either on the AC side (left side of the diodes) or on the DC side (right side of the diodes) of the bridge rectifier. 

This circuit also allows current to flow from both the positive and negative half cycles of the source voltage. In this case there is only one capacitor and the output voltage has a maximum value that is the same as the peak value of the source voltage. The current from the source now must always flow through two diodes. This may have implications on your design if the voltage drop of the diodes is significant compared to the supply voltage amplitude. 

When the supply voltage is greater than the capacitor voltage then the two opposite diodes can conduct current in their forward direction. Since there is no inductor in the circuit the source current immediately jumps to a high level to start charging the capacitor. As the capacitor is charged the current drawn from the supply is now reduces. It reaches zero after the source voltage has reached its maximum. At this point the diodes now turn off. The current to the load is now supplied solely from the capacitor and the capacitor voltage now decreases. The capacitor current is shown in green and shows when the capacitor is being charged and discharged. 

For the negative half cycle the other two diodes will now conduct when the source voltage is greater than the capacitor voltage. The smaller the load resistor, the faster the capacitor discharges so the diodes will turn on earlier at a lower source voltage level. However a smaller capacitor results in larger voltage ripple but a lower peak current level. While for large capacitor values, the ripple is less but the current peak is now much higher since the current flows from the source for a shorter time. This high peak current level has implications on the current rating of the diode. 

The applet also shows the harmonic spectrum of the source current. Ideally a sinusoidal voltage source should produce sinusoidal current at the same fundamental frequency as the voltage. For this bridge rectifier with capacitor circuit the current drawn from the supply is not sinusoidal, it has a triangular shape. Therefore this current shape contains frequencies other than those of the fundamental (since it is an odd function then the other frequencies are only the odd multiplies of the fundamental). For the case when the smaller capacitor is used (it produces a lower current peak), the source current has lower magnitude harmonic frequencies than the case using a larger capacitor.

• In the circuit, the time position (red line) on the waveform can be moved to see how the current path changes for each circuit.
• The value of the capacitor and load resistor can be adjusted by dragging the red bars. Notice how the current waveform shape and ripple voltage changes, in particular, for the capacitor value.