We explain what a power supply is, the functions that this device fulfills and the types of power supplies there are.
What is Power supply?
The power or supply source (PSU in English) is the device that is responsible for transforming the alternating current of the commercial electric line that is received at homes (220 volts in Argentina) in DC or direct; which is used by electronic devices such as televisions Y computers, supplying the different voltages required by the components, usually including protection against eventual inconveniences in the electrical supply, such as overvoltage.
Power supplies can be linear or commutative:
- Linear fonts. They follow the scheme of transformer (voltage reducer), rectifier (conversion of voltage alternating to full wave), filter (conversion from full wave to continuous) and regulation (maintenance of the output voltage before variations in the load).
- Commutative sources. These, instead, convert the electric power by means of high frequency switching over transistors power. Linear sources are typically inefficiently regulated, compared to commutative sources of similar power. The latter are the most used when a design compact and low cost.
Power supply functions
The essential functions of the source are four:
- Transformation. There it is possible to reduce the input voltage to the source (220 v or 125 v), which are those supplied by the electrical network. There a coil transformer participates. The output of this process it will generate 5 to 12 volts.
- Rectification. Have the objective to ensure that no voltage fluctuations occur in the weather. An attempt is made with this phase to pass from alternating current to direct current through a component called a rectifier or Graetz bridge. This allows the voltage not to drop below 0 volts, and to always stay above this figure.
- Filtered out. In this phase the signal is flattened to the maximum, this is achieved with one or more capacitors, which retain the current and let it pass slowly, thereby achieving the desired effect.
- Stabilization. When the continuous and almost completely flat signal is already available, it only remains to stabilize it completely.
Types of power supplies
The power sources that feed the PCs are located inside the case and are generally of the AT or ATX type. AT power supplies were used around until the Pentium MMX appeared, at which point ATX began to be used.
The AT sources have connectors to the motherboard (this differentiates them from the ATX) and also, the source is activated through a switch in which there is a voltage of 220 v, which represents a risk when manipulating the PC. Technologically they are quite rudimentary and are hardly used anymore. Also, there was the problem that having two connectors that had to be connected to the motherboard, confusion and short circuits were frequent.
In ATX sources, the source circuit is more modern and is always active, that is, the source is always supplied with a small voltage to keep it on standby. An additional advantage of ATX power supplies is that they do not have an on / off switch, but rather work with a push button connected to the motherboard, this facilitates connections / disconnections. According to their power and the type of box, they are classified into sources on table AT (150-200 W), mid-tower (200-300), tower (230-250 W), slim (75-100 W), on table ATX ( 200-250 W).