Mumbai University > FE > Sem 1 > Basic Electrical and Electronics Engineering

Marks: 2 M

Year: Dec 2012, May 2013

Inductor Filter

Figure shows an inductor filter. An inductor filter consists of a choke in series with the load. The rectified output contains ac as well as dc components. The inductor acts as a short circuit for dc components and part of ac components blocked by it. Only small amount of ac components reach the output. Thus, ac components are reduced or filtered by the inductor.

Capacitor filter

In a capacitor filter, the capacitor is connected in parallel with the load RL. During the positive half cycle the diode DL is forward biased and the diode D2 is reverse biased. Therefore current flows through Dl, charging the capacitor C to a maximum value Vm. Since the capacitor and load Rl are in parallel, the voltage across the capacitor will appear as output voltage. Output voltage increases upto a point A. After point A, input voltage starts decreasing but the capacitor is already charged to a value Vm. Hence, the diode Dl is reverse biased in the positive half cycle itself and capacitor discharges slowly through Rl.