Many circuits require a voltage supply that is constant and unchanging and such circuits would include radios, calculators, computers, monitors, phones, and even cars. Batteries are a good source of constant voltage but since they are usually limited in size, weight, and power capacity the mains electricity are often used. But this source of electricity is constantly changing as it is AC (alternating current), which is not suitable for DC (direct current) circuits. Therefore, an AC-DC converter is needed to convert the alternating current into a direct current! This kit will not only do this but it will also regulate this converted DC source so that it outputs a smooth constant 5V which can be used to power many projects.