ABSTRACT
Electronic circuits normally operate at low voltages and on direct current (DC). A typical circuit operates on 6 V or 9 V DC, but some can work on as little as 1 V. Often this low voltage supply is provided by a battery. A battery is ideal for portable equipment such as a mobile phone or a digital camera. But batteries are fairly expensive to replace, especially if the equipment is to be operated for long periods or requires a large current. In such cases, we prefer to use a power supply that takes power from the mains and converts it to a low voltage DC supply suitable for electronic circuits. DC power supplies are found in many different kinds of electronic equipment from TV receivers and computers to washing machines and cash registers.
