How Does an AC Adaptor Work?

Techwalla may earn compensation through affiliate links in this story. Learn more about our affiliate and product review process here.

Introduction: What is an AC Adaptor?

Also referred to as a power supply or power adaptor, an AC adaptor plugs into a standard electrical outlet and converts the AC electrical current from the wall outlet to the specifications needed by the electrical device that's plugged in. The AC adaptor is a box attached to the power cord, either at the end of the cord where the device plugs into the wall outlet, or in the middle of the power cord.


Tons of devices around your home rely on AC adaptors for their power supply. Laptops, cell phones, cordless phones, digital photo frames, compact disc players, video game systems and that just names a few.

Video of the Day

Technology has yet to lead us to a time when AC adaptors will become universal to all electronic devices.


How an AC Adaptor Works

In short, an AC Adaptor converts the electric currents received by the electrical outlet into a typically lower alternating current that an electronic device can use.

Inside the AC adaptor are two wire windings that wrap around a single iron core. The first of the windings receives the 120-volt alternating current delivered to the electrical outlet, and creates an electric field in the iron core. The second wire winding turns the newly created electric field into a smaller alternating electric current. The measure of the resulting alternating current is dependent upon the number of coils in the second wire winding in relation to the number in the first winding. If the second winding is half of the first winding, the alternating current will measure half of what it did when it entered the AC adaptor. Therefore, if there were 100 coils on the first winding, the second winding will have only 50 coils.


AC/DC: The Two Electric Currents

The abbreviation, AC, stands for alternating current and is used to describe the electrical currents utilized to deliver power from power plants to homes and businesses. When graphed, these alternating currents are shown as waves that go up and down; this is because these currents do not flow constantly in one direction, but alternate directions, flowing forward and backward.



DC, which stands for direct current, describes electrical currents that flow in one direction. Direct currents are produced and present primarily in batteries, and are used mainly by devices that run by battery power.

Converting Alternating Current to Direct Current

For electronics that run on battery power, but may also be plugged into an electrical outlet, AC adaptors are used to convert alternating current into direct current. Inside the adaptor box, behind the two wire windings and the iron core are two rubber wrapped diodes that convert alternating currents into direct current by allowing them to flow in a single direction.


Traveling Abroad

Remember when traveling out of the country that you will need to purchase converters to adapt the voltage and frequency of currents to match the devices you intend to use. While residents of the United States are used to receiving currents at 120 volts and a 60 hertz frequency, residents of Ireland receive currents at 220 volts and 50 hertz frequency.



Report an Issue

screenshot of the current page

Screenshot loading...