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Power Supply


A power supply is a hardware component that supplies power to an electrical device. Power supply does not actually provide power to devices. It main functions is converting AC (Alternating Current) from power source such as electrical outlet to DC (Direct Current). There are also DC-DC power supplies that enables device to use DC sourced supply for example car outlet. But these are not commonly used. Power supply also converting power to the correct voltage, current, and frequency for the device. It is a very important part for any electrical equipment to work properly because not every device work on the same parameters.


Power supplies composed of four components that each carry out a function in order:

  • Transformers regulate the incoming voltage. After a current and voltage inputted, it either step up or step down the voltage to match a device’s requirements.

  • Rectifiers convert the incoming AC to DC. There are three types namely half-wave, full-wave or bridge.

  • Filters smooth out the waves in the current after it’s converted to DC. The power outputted from the filter is smoother but not completely flat.

  • Voltage regulators completing the job of the filter by eliminating any excess ripples that can cause overheating or underpowered device. It removes any voltage surges or drops.


Rectifiers or Silicon diode rectifiers have three types of models to convert AC power to DC. Each model has its own benefits and process.


  • Half wave: Uses a single silicon diode, but only converts half of the AC wave. This will cause in a greater ripple in the resulting wave that harder to remove with a regulator. Half wave rectifier does not perform as efficiently as other models and usually used to supply power to devices of low importance. It also cheaper than the other models.

  • Full wave: This rectifier needs specialized transformer which is more efficient, but also increases the price. It requires a center tap in the secondary winding. Full wave rectifier also produces less ripple in the resulting wave, so it is easier to be removed by a regulator.

  • Bridge: This is the most efficient rectifier that blends the advantage of half wave and full wave models. Bridge model uses four diodes to convert a full AC wave to DC wave. These eliminate the need of a special center tap transformer. It also the most expensive model.


A power supply can also receive energy from energy storage device such as batteries, fuel cells, generators, or another power supply. These energy source sometimes experience certain problems such as voltage surge (over/under). Power supply designed to handle these problems and provide a steady stream of regulated and consistent power output. Some even includes a fuse that blows when the surge is too much to handle. The power supply will break but the main device will be protected. After all, it is cheaper to change power supply than the entire device.


Power supply can either be external or internal. Most Personal Computer (PC) have internal power supply that housed inside a casing with other components such as motherboard, storage device, and Graphical Processing Unit (GPU). Others like laptops or external hard drive use external power supplies to charge the battery inside the device. These power supplies are usually encased in their own protective case and connected directly to electrical outlet by a cable. They also often connected to the main device using another cable. This design enables the main device to have sleeker design and size by putting the power supply outside the unit.


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