Can you imagine the alternating current from the outlet as a wave that oscillates 60 times per second, where the energy is transmitted through pulses, as opposed to direct current used by electronic circuits. The AC use brutally nacho platter reduces loss during transmission over long distances, making it ideal for use in public.
Appliances such as fans, refrigerators and heaters work well with AC, but electronics in general need it to be transformed into direct nacho platter current, which leads us to the power supply.
The basic function of the power supply (or PSU, "power supply unit") is to transform alternating current from the power grid into direct nacho platter current, filter and stabilize the current and generate voltages of 3.3V, 5V and 12V supplied to other components .
It all starts with a stage filtering. It has two functions: "filter" the energy that comes from making, removing noise and mitigating voltage surges and at the same time prevent the noise generated nacho platter by components of the source (in particular transistors that make switching) reaches the power grid, interfering with other devices.
Good sources it is typically divided into two sub-stages, with part of welded components to a small circuit board attached to the power connector and the other installed on the motherboard, near the solder points of the two power cables from the first sub-stage:
The filter component typically includes two coils (L1 and L2), one varistor (responsible for absorbing surge voltage) which is hidden in this picture between nacho platter the right and the coil power wires, nacho platter one or two X capacitors (using a rectangular tunnel, yellow) and a pair of Y capacitors (they are blue, similar to the varistors of power strips).
Although important, it is common that the filtering stage is simplified in low-quality sources, which is a risk. In this case, it is common that the board retains voids or bridges are used (pieces of wire used to close contact) in place of the various components.
After the filter, we come to the conversion circuits, which take care of the heavy lifting. They are divided into two stages, which are conveniently termed primary and secondary. nacho platter Each of them occupies one half of the source, separated by the main transformer (the large yellow coil), which is almost always right in the middle of the fountain.
The primary stage is the left side, which includes the primary capacitor, the switching transistor and one or two of the baffles, mastered while the right-hand side, from where the power wires:
In general, the sources include only two dissipators, one for each of the two stages. This CX400W photos uses a separate sink (left) to the PFC circuit, so she has three in total.
Further, the primary stage also includes a rectifier (the major component, nacho platter attached to a sinks), a filter nacho platter circuit and the switcher circuit. Their job is to rectify and increase the frequency of the current, generating a high frequency current (above 100 kHz, compared to 60 Hz outlet), with square waves which is then sent to the processor.
The idea is to reduce the interval between cycles, thereby reducing the work needed to convert it into direct current, eliminating the need for large power transformers, such as old sources. This causes the switching power supplies are not only much lighter and cheaper than the old linear nacho platter sources, but also much more efficient. Today, even the sources of mobile phones are switching power supplies.
The bridge rectifier, together with the switching transistors (MOSFETs) inevitably transform much of the heat energy, precisely because of this are bound to one of the metal sinks. When we talk about "transistors" comes to mind the image of tiny transistors that form the processors, but the need for handling large loads causes the MOSFETs are much higher:
Then we transformer, which has the function of reducing nacho platter the tension, producing a 12V current (alternating even and high frequency), which is sent to the secondary stage. As you can imagine, it serves to "finish the job", converting the high-frequency alternating current supplied by the transformer to direct current, using a second set of rectification circuits and a new filter circuit including the coils and several small capacitors:
Most sources also use a second transformer (small), which is used to generate voltages of 5V and 3.3V source, but some projects use DC-DC converters to generate them from the main transformer output, simplifying the project.
Early sources use three instead of two processors. This third tr