The types of electrical circuits power supply of the computer
Operation of any computer impossible without a power supply. Therefore it is necessary to take seriously the choice. Because of stable and reliable operation of the PSU will depend on the performance of the computer itself.
What it is
The main task of the power supply is to convert alternating current, and then forming the required voltage for normal operation of all components of the PC.
The voltage required to operate your components:
- +3.3 V.
In addition to these stated values exists and additional quantities:
BP plays the role of galvanic isolation between the electrical current from the socket and components current consumption. A simple example, if there is a current leak and the man touched the casing of the system unit it would hit the shock, but thanks to the power supply this does not happen. Often used power supplies (IPS) dimensions.
Overview of schemes of power sources
The main part of the structural scheme of IP, ATX is a half-bridge Converter. Work converters of this type is to use the push-pull mode.
Stabilization of output parameters of the SP is carried out by use of pulse width modulation (PWM controller) control signals.
In switching power supplies often used the chip PWM controller TL494, which has a number of positive properties:
- acceptable performance of the chip. This is a small starting current, speed;
- the existence of universal internal elements of protection.
- the ease of use.
Simple switching-mode power supply
The operating principle of a conventional pulse BP can be seen in the photo.
The first unit performs the change from AC to DC. The Converter is designed in the form of a diode bridge that converts the voltage, and a capacitor for smoothing fluctuations.
In addition to these elements, there may be even additional accessories: filter voltage and thermistors. But, because of the high cost, these components may be missing.
The generator creates pulses with a certain frequency, which feed the transformer. The transformer performs the main work in BP, it is the galvanic isolation and conversion of current to desired values.
Further, AC voltage generated by the transformer, goes to the next block. This block of diodes, equalizing the voltage and filter ripple. The filter consists of capacitors and inductor.
Video: the working Principle of the PWM controller of the PSU
ATX without correction coefficient
Simple switching-mode power supply, though working the device, but in practice it is inconvenient to use. Many of its parameters at the output «float», including voltage. All these parameters change due to unstable voltage, temperature and load of the transmitter output.
But if you control these parameters via the controller, which will act as a stabilizer and additional features, the scheme is quite suitable for the application.
Structural diagram of power supply using the controller pulse-width modulation is simple and is the pulse generator in PWM controller.
The PWM controller adjusts the amplitude change of the signals passing through the low pass filter (LPF). The main advantage are high efficiency power amplifiers and broad opportunities to use.
ATX with power factor correction
In new sources of supply for the PC there appears an additional block PFC function (PFC). CMC takes away the appearing error bridge rectifier AC current and improves the power factor (KM).
Therefore, manufacturers are actively produced along with the obligatory correction of KM. This means that IP on the computer will work in the range of 300W and more.
In these bps use a special inductor with inductance higher than the input. This SP is called PFC or passive PFC. Has an impressive weight because of the additional use of capacitors on the rectifier output.
Of the shortcomings can be identified the low reliability of the SP may not work with the UPS at the time of switching the operation mode «battery/network».
This is due to the small capacitance of the filter network voltage at the time of voltage drop increases the current CMC, and at this point includes short-circuit protection.
For dual channel PWM controller
Often used in modern power supplies for computer two channel PWM controllers. The only chip capable of performing the role of the transmitter and a corrector KM, which reduces the total number of elements in the schema BP.
In the above diagram the first part performs the formation of the stable voltage of +38V and the second part is a Converter which generates a stabilized voltage of +12V.
Connection diagram computer power supply
To connect the power supply to the computer to perform a series of sequential steps:
- to install the PSU in the system unit. All these steps must be performed carefully so as not to hurt the other components;
- to secure the PSU to the rear panel of the system unit special screws;
- connect the power cables to all devices in the system unit (motherboard, floppy drive, video card, hard drive). Special preferences in the order of connection is not important to do everything carefully and correctly.
For connecting components of a personal computer on the PSU has different connectors. On the back is a connector for the network cable and button switch.
In addition can be located on the back wall of the PSU and a connector to connect the monitor.
In various models there may be other connectors:
- voltage indicator;
- button changes the operating mode of the fan;
- switch input voltage;
- USB ports built into the PSU.
Modern power supplies for PC less set the fan on the back wall, which pulled the hot air from the PSU. In return, this decision started to use the fan on the ceiling, which was larger and worked quietly.
On some models it is possible to meet two fan. From the wall, which is located inside the system unit, turns out the wire with the special connector for the power supply to the motherboard. In the photo are all possible connectors and the terminal.
Each color wire supplies a certain voltage:
- yellow — +12 V;
- red — +5V;
- orange — +3.3 V;
- black is the ground.
Different manufacturers can change the values for these colors of wires.
Also there are connectors for the power supply components of the computer.
Parameters and characteristics
BP personal computer has many parameters that can not be specified in the documentation. On a side label shows a few parameters – the voltage and wattage.
Power – main index
This information is written on the label in large font. Capacity of the PD indicates the total amount of power available for internal components.
It would seem that to choose a PSU with the required capacity will be sufficient to summarize the indicators of consumption components and to choose the BP with a small margin. So the big difference between 200w and 250w will not be significant.
But actually the situation is more complicated, because the output voltage can range +12V, -12V and others. Each line voltage consumes a certain power. But BP is one transformer, which generates all the voltages used by the PC. In rare cases can be placed two transformers. This is an expensive option and is used as the source servers.
For simple BP used 1 transformer. Because of this, the power lines of voltages may vary, increase at low load on the other lines and Vice versa to decrease.
When choosing a PSU you should pay attention to the maximum values of working voltages and a range of incoming voltages, it needs to be from 110V to 220V.
However most of users do not pay their attention and choosing BP ranges from 220V to 240V at risk to the emergence of frequent shutdowns of the PC.
This PSU will turn off when the voltage drops, which is not uncommon for our power grids.The excess of the stated parameters will lead to a shutdown PC, the protection is activated. To turn back the PSU will have to unplug it and wait a minute.
It should be remembered that the processor and video card consume the higher working voltage of 12V. Therefore, you should pay attention to these indicators.To reduce the load on the connectors, the 12V line is divided into a few parallel with the designation of +12V1 and +12V2. These indicators should be indicated on the label.
Tips for choosing a source
Before choosing to buy BP, you should pay attention to power consumption of internal PC components.
But some video cards require a special current consumption +12V and these figures should be considered when choosing a PSU. Usually for the PC, which has one graphics card is enough of a source with a power of 500W or 600.
You should also read the reviews customers and reviews of experts about a selected model and company manufacturer. The best settings that you should pay attention to is power, quiet operation, quality and compliance characteristics written on the label.
To save when it should not, because of the work of BP will depend on the work PC. Therefore, the better and more reliable source, the longer the computer. The user can be sure I made the right choice and not worry about the sudden shutdowns of your PC.