Which type of filter is independent of load why?

Answer 1

LC filter

It is a combination of inductor and capacitor filter. Here an inductor is connected in series and a

capacitor is connected in parallel to the load as shown in fig 5.6. As discussed earlier, a series inductor

filter will reduce the ripple, when increasing the load current. But in case of a capacitor filter it is

reverse that when increasing current the ripple also increases. So a combination of these two filters

would make ripple independent of load current. The ripple factor of a chock input filter is given by

Since the d.c. resistance of the inductor is very low it allows d.c. current to flow easily through it. The

capacitor appears open for d.c. and so all d.c. component passes through it. The capacitor appears open

for d.c. and so all d.c components passes through the load resistor RL.

Bleeder resistor

For optimum functioning, the inductor requires a minimum current to flow through, at all time. When

the current falls below this rat, the output will increase sharply and hence the regulation become poor.

To keep up the circuit current above this minimum value, a resistor is permanently connected across the

filtering capacitor and is called bleeder resistor. This resistor always draws a minimum current even if

the external load is removed. It also provides a path for the capacitor to discharge when power supply is

turned off.