Block Schematic of Regulated Power Supply

Block Schematic of Regulated Power Supply

• A typical d.c. power supply consists of various stages. The Fig. 1.23.1 shows the block diagram of a typical d.c. power supply consisting of various circuits. The nature of voltages at various points is also shown in the Fig. 1.23.1.

• The a.c. voltage (230 V, 50 Hz) is connected to the primary of the transformer. The transformer steps down the a.c. voltage, to the level required for the desired d.c. output. Thus, with suitable turns ratio we get desired a.c. secondary voltage. The rectifier circuit converts this a.c. voltage into a pulsating d.c. voltage. A pulsating d.c. voltage means a unidirectional voltage containing large varying component called ripple in it. The filter circuit is used after a rectifier circuit, which reduces the ripple content in the pulsating d.c. and tries to make it smoother. Still then the filter output contains some ripple. This voltage is called unregulated d.c. voltage. A circuit used after the filter is a regulator circuit which not only makes the d.c. voltage smooth and almost ripple free but it also keeps the d.c. output voltage constant though input d.c. voltage varies under certain conditions. It keeps the output voltage constant under variable load conditions, as well. The output of a regulator is called d.c. supply, to which the load can be connected. Nowadays, complete regulator circuits are available in the integrated circuit (IC) form.

Key Point : Thus a voltage regulator circuit is the one which is designed to keep the output voltage of a power supply nearly constant, under varying input voltage conditions and varying load conditions.

Review Question

1. Draw and explain block schematic of regulated power supply.