An adapter is a physical device that allows one hardware or electronic interface to be adapted (accommodated without loss of function) to another hardware or electronic interface. In a computer, an adapter is often built into a card that can be inserted into a slot on the computer's motherboard. The card adapts information that is exchanged between the computer's microprocessor and the devices that the card supports.





Alternating current adapters convert the AC power from your wall outlet to a smaller voltage direct current power for your electronic device. They accomplish this in two steps, first scaling the voltage and then converting the AC to DC. There are many kinds of AC DC adapter with different models like 7.5W Max Wall Mounted Adapter, 13.5W Max Wall Mounted Adapter, 24W Max Wall Mounted Adapter, Interchangeable Adapter, 18W Max Wall Mounted Adapter, etc.





Voltage


The AC adapter scales the 120 volts from your wall down to a voltage in the area of 6 to 18 volts using a small transformer. A transformer consists of two coils of wires interspersed around an iron core. By electromagnetic law, the ratio of the number of coil turns in one wire to the other will equal the ratio of the voltages in the two wires.





Rectifying


After converting the power to the desired voltage level, the adapter converts the AC to DC using a setup called a rectifier. The rectifier uses a combination of diodes, one-way electronic components, to make constant DC power from alternating AC power.





Example


A 12-volt adapter performs the following steps. First, the 120 volts of AC power from the wall goes into one end of the transformer, which has 10 coil windings on the input for every 1 on the output, and induces 12-volt AC power. Next, the AC power goes through a series of diodes and comes out as 12 volts DC, ready to power your laptop, your home telephone, or to charge your cellphone.





Apart from adapter, you may also neef a suitable power supply. The commonly used power supply, with electronic circuits is the line operated power supply. In this the mains voltage is utilized in a transformer or directly, to work a rectifier. The rectified output, will be filtered using a filter circuit, that eliminates the ripple content of the rectified output. The output of the power supply will be pulsating unidirectional current.





The transformer isolates the load from the mains power supply ground. It provides either a step up voltage or step down voltage in its secondary. Taps or center tap or both can be provided at the secondary of the transformer. A rectifier converts the alternating current to pulsating unidirectional current. Mostly Full wave rectifier, or bridge rectifier circuits are used as rectifier circuits.





There are various of power supplies designed for different models such as 65W Max Desktop Power Supply, 90W Max Desktop Power Supply, 60W Max Power Supply,250W Max Desktop Power Supply and many other kinds of desktop power supplies.