A fluctuating DC voltage may result in an erratic operation of electronic devices and circuits. In order to avoid poor voltage regulation due to fluctuation in DC voltage, it is necessary to use a voltage regulator circuit in DC power supply.
- The regulated DC power defines a DC power supply which maintains the DC voltage constant irrespective of AC input fluctuations in load resistance values.
- The block diagram of a regulated DC power supply is shown in above figure. It consists of rectifier, filter and voltage regulator circuits. The load may be connected across the voltage regulator.
- Commonly the bridge rectifier is used in regulated power supply. Its function is to convert the AC mains voltage to the rectified DC voltage.
- The voltage contains small amount of ripple the pulsating voltage is passed through the filter circuit. Its function is to bypass the filter.
- The pulsating opposes the AC fluctuations. This voltage is applied to the voltage regulator. Its function is to maintain the output DC voltage constant irrespective of fluctuations in AC mains voltage and variations in currents load. Thus, the regulated power supply gives the stable DC voltage across the load.