Intro Into Power Supplies

intro into power supplies

Any electrical device, including a computer, needs power in order to operate properly and the device responsible for supplying that power is, creatively enough, called the power supply. What the power supply actually does is converting the alternating voltage (AC), supplied by the power system, into continuous voltage (DC). In other words, the power supply converts conventional 110V or 220V alternating voltage into continuous voltage required by the PC electrical components which are +3.3V, +5V, +12V and -12V. AC voltage may vary throughout the world, but in order to simplify the matter, we will use 110V to include 110V, 115V and 127V, whereas, for voltages of 220V, 230V and 240V, we will use the 220V label. Australia’s power grid, for example, uses 230V, while Japan is the only country in the world outside this range and its residential voltage is 100V.
You can find two basic designs of power supplies Australia wide: linear and switching-mode.

The way linear power supplies work is by getting the 110V or 220V from the power grid and lowering its value to let’s say 12V, with the use of a transformer. But this new voltage is still AC. The adjustment is done with a set of 2 diodes that transform the AC into pulsing voltage, which is then filtered by an electrolytic capacitor into almost DC voltage. The final stage that transforms this voltage into true DC is done by a zener diode, often with the aid of a power transistor.
While linear power supplies work well for low-power applications, when high power is needed, for example for a PC, linear power supplies can be insanely large and impractical since the size of the transformer and capacitor are inversely proportional to the AC voltage frequency. To put it simply, the lower the AC frequency, the larger the size of the components and the other way around. Since most power grids use a very low 60Hz or 50Hz frequency, depending on the country, the transformer and the capacitor would be huge.
The solution to this problem is to use a switching-mode power supply. What the switching-mode power supply(SMPS) does is increasing the frequency of the input voltage before sending it to the transformer. With the input voltage increased in the range of kHz, the transformer and capacitors can be very small. Keep in mind that the switching is referred to the high-frequency switching and has nothing to do with the power supply having an on/off switch.
Usually, when buying a computer we focus on the processor, the motherboard, the graphic card, the memory, and it is the power supplies Australia consumers most often neglect. The fact of the matter is, the power supply is the heart of the machine which supplies the fuel for the rest of the components to function properly.
This is why you should always go for a high-quality powers supplies that will not only increase the durability of your PC and lower your electricity bill, but will also spare you from problems like random resets and freezes, or the infamous blue screen, that often occur from poor-quality power supplies.

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