Computers cannot work without electricity. To charge them, special devices called power supplies are used. They receive AC voltage from the grid and convert it to DC. The devices can deliver huge amounts of power in a small form factor and have built-in overload protection. Their output parameters are incredibly stable, and the quality of direct current is ensured even at high loads. When there is an extra such device, it is reasonable to use it for many everyday tasks, for example, converting it into a charger from a computer power supply.
Desktop Power Supply Design
The block is shaped like a metal box with a width of 150mm x 86mm x 140mm. It is standardly mounted inside the PC case with four screws, a switch and a socket. This design allows air to enter the power supply (PSU) cooling fan. In someIn some cases, a voltage selector switch is installed to allow the user to select values. For example, the United States has an internal power supply that operates at a nominal voltage of 120 volts.
The computer power supply consists of several components inside: coils, capacitors, an electronic board for current regulation and a fan for cooling. The latter is the main cause of failure for power supplies (PS), which must be considered when mounting a charger from an atx computer power supply.
Personal computer power supply types
IPs have a certain power, indicated in watts. A standard unit is typically capable of delivering around 350 watts. The more components installed on the computer: hard drives, CD / DVD drives, tape drives, fans, the more power is required from the power supply.
Specialists recommend using a power supply that provides more power than the computer needs, as it will run in a constant "underload" mode, which will increase the life of the machine by reducing the thermal effect on its internal components.
There are 3 types of IP:
- AT Power Supply - Used on very old PCs.
- ATX power supply - still used on some PCs.
- ATX-2 power supply - commonly used today.
PSU parameters that can be used when creating a charger from a computer power supply:
- AT / ATX / ATX-2:+3.3 V.
- ATX / ATX-2:+5B.
- AT / ATX / ATX-2:-5 V.
- AT / ATX / ATX-2:+5 V.
- ATX / ATX-2:+12 V.
- AT / ATX / ATX-2:-12V.
Motherboard connectors
There are many different power connectors in the PI. They are designed in such a way that you cannot make a mistake when installing them. To make a charger from a computer power supply, the user will not have to choose the right cable for a long time, as it simply will not fit in the connector.
Types of connectors:
- P1 (PC / ATX connector). The main task of the power supply unit (PSU) is to provide power to the motherboard. This is done via 20-pin or 24-pin connectors. 24 pin cable is compatible with 20 pin motherboard.
- P4 (EPS connector). Previously, the motherboard pins were not sufficient to provide processor power. With an overclocked GPU reaching 200W, it was possible to provide power directly to the CPU. Currently it is P4 or EPS which provide enough CPU power. Therefore, converting a computer power supply into a charger is economically justified.
- PCI-E connector (6-pin 6 + 2 connector). The motherboard can provide a maximum of 75W through the PCI-E interface slot. A faster dedicated graphics card requires much more power. The PCI-E connector was introduced to solve this problem.
Cheap motherboards are equipped with a 4-pin connector. More expensive "overclocking" motherboards have 8-pin connectors. Additional provideexcessive processor power during overclocking.
Most power supplies come with two cables: 4-pin and 8-pin. Only one of these cables should be used. It is also possible to split the 8-pin cable into two segments to ensure backward compatibility with cheaper motherboards.
Power for graphics cards
The left 2 pins of the 8-pin connector (6+2) on the right are disconnected for backwards compatibility with 6-pin graphics cards. The 6-pin PCI-E connector can supply an extra 75W per cable. If the graphics card contains one 6-pin connector, it can be up to 150W (75W from motherboard + 75W from cable).
More expensive graphics cards require an 8-pin (6+2) PCI-E connector. With 8 pins, this connector can deliver up to 150W per cable. A graphics card with one 8-pin connector can draw up to 225W (75W from motherboard + 150W from cable).
Molex, 4-pin peripheral connector, used when creating a charger from a computer power supply. These pins are very long lasting and can supply 5V (red) or 12V (yellow) to peripherals. In the past, these connections were often used to connect hard drives, CD-ROM players, etc.
Even the Geforce 7800 GS video cards are equipped with Molex. However, their power consumption is limited, so most of them have now been replaced by PCI-E cables and SATA cables. All that's left ispowered fans.
Accessory Connector
The SATA connector is a modern replacement for the obsolete Molex. All modern DVD players, hard drives and SSDs run on SATA power. The Mini-Molex/Floppy connector is completely obsolete, but some PSUs still come with a mini-molex connector. They were used to power floppy drives up to 1.44 MB of data. They have mostly been replaced by the USB stick today.
Molex-PCI-E 6-pin adapter for video card power supply.
When using the 2x-Molex-1x PCI-E 6-pin adapter, you first need to make sure that both Molex are connected to different cable voltages. This reduces the risk of overloading the power supply. With the introduction of the ATX12 V2.0, changes were made to the 24-pin connector system. Older ATX12Vs (1.0, 1.2, 1.2 and 1.3) used a 20-pin connector.
There are 12 versions of the ATX standard, but they are so similar that the user does not need to worry about compatibility when mounting a charger from a computer power supply. For backwards compatibility, most modern sources allow the last 4 pins of the main connector to be disconnected. It is also possible to create advanced compatibility with an adapter.
Computer supply voltages
The computer requires three types of constant voltage. 12 volts is needed to supply voltage to the motherboard, graphics cards, fans, processor. The USB ports require 5 volts, while the CPU itself uses 3.3 volts. 12 volt alsoapplicable to some "smart" fans. An electronic board in the power supply is responsible for sending the converted electricity through special cable sets to power devices inside the computer. The components listed above convert AC voltage into pure DC current.
Almost half of the work a power supply does is done with capacitors. They store energy to be used for continuous work flow. When making a battery charger from a computer power supply, the user must be careful. Even if the computer is turned off, there is a chance that electricity will be stored inside the power supply in capacitors, even several days after the shutdown.
Cable set color codes
Inside the power supplies, the user sees many cable sets coming out with different connectors and different numbers. Power cable color codes:
- Black, used to provide current. Every other color must be connected to the black wire.
- Yellow: + 12V.
- Red: +5 V.
- Blue: -12V.
- White: -5V.
- Orange: 3.3V.
- Green, control wire for checking DC voltage.
- Purple: + 5 Standby.
Computer power supply output voltages can be measured with a proper multimeter. But due to the higher risk of short circuit, the user should always connect the black cable with the black one on the multimeter.
Power plug
The hard drive wire (regardless of whether it is IDE or SATA) has four wires attached to the connector: yellow, two black in a row, and red. The hard drive uses both 12V and 5V at the same time. 12V powers the moving mechanical parts, while 5V powers the electronic circuits. So all these cable kits are equipped with both 12V and 5V cables at the same time.
Electrical connectors on the motherboard for CPU or chassis fans have four pins to support the motherboard for 12V or 5V fans. Apart from black, yellow and red, other colored wires can only be seen in the main connector, which directly transitions into the motherboard socket. These are purple, white or orange cables and are not used by consumers to connect peripherals.
Turning on ATX without a computer
If you want to make a car charger from a computer power supply, you need to test it. You will need a paperclip and about two minutes of your time. If you need to connect the power supply back to the motherboard, you just need to remove the paperclip. There will be no change from using a paperclip.
Procedure:
- Find the green wire in the cable tree from the power supply.
- Follow it to 20 or 24 pin ATX. The green wire is in a sense a "receiver", which is needed to supply energy to the power supply. There are two black wires between it.grounding.
- Place the paperclip in the pin with the green wire.
- Place the other end into one of the two black ground wires next to the green one. It doesn't matter which one will work.
Although the paperclip will not deliver high current, it is not recommended to touch the metal part of the paperclip while it is energized. If you want to leave the paper clip indefinitely, wrap it with duct tape.
Creating a Charger
If you start making a charger from a computer power supply with your own hands, take care of the safety of your work. The source of the threat is capacitors, which carry a residual charge of electricity that can cause significant pain and burns. Therefore, you need to not only make sure that the PI is securely turned off, but also wear insulating gloves.
After opening the PSU, make an assessment of the workspace and make sure that there will be no problems with clearing the wires.
Pre-think over the design of the source, measuring with a pencil where the holes will be to cut the wires of the required length.
Perform wire sorting. In this case, you will need: black, red, orange, yellow and green. The rest are redundant, so they can be cut off on the circuit board. Green indicates power on after standby. It is simply soldered to the ground black wire, which will ensure that the PSU turns on without a computer. Next, you need to connect the wires to 4 large clips, one for each set of colors.
After that, you need to group the 4-wire colors together and cut them to the required length, remove the insulation and connect at one end. Before drilling holes, care must be taken to ensure that the PCB of the chassis is not contaminated with metal chips.
In most PSUs, the PCB cannot be completely removed from the chassis. In this case, it must be carefully wrapped in a plastic bag. Having finished drilling, it is required to process all rough spots and wipe the chassis with a cloth from debris and plaque. Then install the fixing posts using a small screwdriver and terminals, securing them with pliers. After that, close the power supply and mark the voltage on the panel with a marker.
Specialists recommend installing rubber feet on the bottom of the device so that it does not lie on the floor.
Charging a car battery from an old PC
This device will help the car enthusiast in a difficult situation when you urgently need to charge the car battery without a standard device, but using only a regular PC power supply. Experts do not recommend constantly using a car charger from a computer power supply, since the voltage of 12 V is a little short of what is needed when charging the battery. It should be 13 V, but it can be used as an emergency option. To amplify the voltage where it used to be 12V, you need to change the resistor to 2.7kOhm on the trimmer resistor installed on the additional power supply board.
Because sourcespower supplies have capacitors that store electricity for a long time, it is advisable to discharge them using a 60 W incandescent lamp. To attach the lamp, use the two ends of the wire to connect to the terminals on the cover. The backlight will slowly go out, discharging the cover. Shorting the terminals is not recommended as this will cause a large spark and may damage the PCB tracks.
The procedure for making a do-it-yourself charger from a computer power supply begins by removing the top panel of the power supply. If the top panel has a 120mm fan, disconnect the 2-pin connector from the PCB and remove the panel. It is required to cut the output cables from the power supply with pliers. Do not throw them away, it is better to reuse them for non-standard tasks. Leave no more than 4-5 cables for each tie post. The rest can be cut off on the PCB.
Wires of the same color are connected and secured using cable ties. The green cable is used to turn on the DC power supply. It is soldered to the GND terminals or connected to the black wire from the bundle. Next, measure the center of the holes on the top cover, where the fixing posts should be fixed. You need to be especially careful if a fan is installed on the top panel, and the gap between the edge of the fan and the power supply is small for the fixing pins. In this case, after marking the center points, you need to remove the fan.
AfterTo do this, you need to attach the fixing posts to the top panel in the order: GND, +3, 3V, +5V, +12V. Using a wire stripper, the insulation of the cables of each bundle is removed, and the connections are soldered. The sleeves are treated with a heat gun over the crimp connections, after which the protrusions are inserted into the connecting pins and the second nut is tightened.
Next you need to put the fan back in place, connect the 2-pin connector to the socket on the PCB, insert the panel back into the unit, which may require some effort due to the bundle of cables on the crossbars and close.
Charger for screwdriver
If the screwdriver has a voltage of 12V, then the user is lucky. It can make a power supply for the charger without much rework. You will need a used or new computer power supply. It has several voltages, but you need 12V. There are many wires of different colors. You will need yellow ones that give out 12V. Before starting work, the user must make sure that the power supply is disconnected from the power source and has no residual voltage in the capacitors.
Now you can start converting your computer's power supply into a charger. To do this, you need to connect the yellow wires to the connector. This will be the 12V output. Do the same for the black wires. These are the connectors into which the charger will be connected. In the block, the 12V voltage is not primary, so a resistor is connected to the red 5V wire. Next, you need to connect the gray and one black wire together. This is a signal that indicates power supply. The color of this wire mayvary, so you need to make sure it's a PS-ON signal. This should be written on the sticker on the power supply.
After turning on the switch, the PSU should start, the fan should rotate, and the light should light up. After checking the connectors with a multimeter, you need to make sure that the unit is producing 12 V. If so, then the screwdriver charger from the computer power supply is functioning correctly.
Tips from experienced
In fact, there are many options for adapting the power supply to your own needs. Fans of experimenting are happy to share their experience. Here are some good tips.
Users don't be afraid to upgrade the block box: add LEDs, stickers, or whatever you need to improve. When disassembling the wires, you need to make sure that an ATX power supply is used. If it's an AT or older power supply it will most likely have a different color scheme for the wires. If the user does not have data about these wires, he should not re-equip the unit, as the circuit may be assembled incorrectly, which will lead to an accident.
Some modern power supplies have a communication wire that must be connected to the power supply for it to work. The gray wire connects to orange, and the pink wire connects to red. A power resistor with high power may become hot. In this case, you need to use a radiator for cooling in the design.
