Power Supply

All electronic circuits need a power supply to function. Electronic components (and therefore circuits built with them) work on direct current (DC) and generally have a voltage requirement of between 3 and 12 volts with a maximum current of about 2 amperes.

You must check the voltage and current rating of each component that you use in the circuit. If you use a power supply that is lower than the component rating, then it may not function correctly. And if you use a higher supply than component rating, then it may get damaged.

DC power supply can be provided by batteries, but they discharge quickly and need frequent replacement or recharging.

An alternative is to use the AC power supply used to power electrical appliances. If using an AC power source, you will need a transformer to first convert the high input voltage (100V-240V) to a lower voltage (3V-12V). Then you will need a rectifier to convert the alternating current to a direct current.

One of the most common ways to power development microcontrollers and circuits is via a USB cable connected to your computer. The computer provides a steady, regulated 5V supply which is required by most microcontroller boards.

This approach has a dual benefit since the connection via the USB cable is also used to upload programs to the microcontroller and to exchange data via the serial port (the USB port).

Switched Mode Power Supply (SMPS)

An SMPS is an electronic power supply that incorporates a switching regulator to convert electrical power efficiently. Like other power supplies, an SMPS transfers power from an AC source to DC loads, such as a personal computer, while converting voltage and current characteristics. These are expensive and not required for simple circuits but are useful if you have expensive or sensitive circuits.