Charger from computer power supply. Charger based on ATX power supply

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A diagram of a simple modification of an ATX power supply so that it can be used as a car battery charger. After the modification, we will get a powerful power supply with voltage regulation within 0-22 V and current 0-10 A. We will need a regular ATX computer power supply made on a TL494 chip. To start an ATX type power supply that is not connected anywhere, you need to short-circuit the green and black wires for a second.

We solder out the entire rectifier part and everything that is connected to legs 1, 2 and 3 of the TL494 microcircuit. In addition, you need to disconnect pins 15 and 16 from the circuit - this is the second error amplifier that we use for the current stabilization channel. You also need to unsolder the power circuit connecting the output winding of the power transformer from the + power supply of the TL494, it will be powered only by a small “standby” converter, so as not to depend on the output voltage of the power supply (it has 5 V and 12 V outputs). It is better to reconfigure the duty room a little by selecting a voltage divider in the feedback and obtaining a voltage of 20 V for powering the PWM and 9 V for powering the measuring and control circuit. Here is a schematic diagram of the modification:

We connect the rectifier diodes to the 12-volt taps of the secondary winding of the power transformer. It is better to install more powerful diodes than those that are usually found in a 12-volt circuit. We make choke L1 from a ring from a group stabilization filter. They are different in size in some power supplies, so the winding may differ. I got 12 turns of wire with a diameter of 2 mm. We take choke L2 from the 12 Volt circuit. An output voltage and current measuring amplifier is assembled on the LM358 op-amp chip (LM2904, or any other dual low-voltage op-amp that can operate in single-pole switching and with input voltages from almost 0 V), which will provide control signals to the TL494 PWM. Resistors VR1 and VR2 set the reference voltages. Variable resistor VR1 regulates the output voltage, VR2 regulates the current. Current measuring resistor R7 is 0.05 ohm. We take power for the op-amp from the output of the “standby” 9V power supply of the computer. The load is connected to OUT+ and OUT-. Pointer instruments can be used as a voltmeter and ammeter. If current adjustment is not needed at some point, then simply turn VR2 to maximum. The operation of the stabilizer in the power supply will be like this: if, for example, 12 V 1 A is set, then if the load current is less than 1 A, the voltage will stabilize, if more, then the current. In principle, you can also rewind the output power transformer, the extra windings will be thrown out and you can install a more powerful one. At the same time, I also recommend setting the output transistors to a higher current.

At the output there is a load resistor somewhere around 250 ohm 2 W in parallel with C5. It is needed so that the power supply does not remain without load. The current through it is not taken into account; it is connected before the measuring resistor R7 (shunt). Theoretically, you can get up to 25 volts at a current of 10 A. The device can be charged with both regular 12 V batteries from a car and small lead batteries that are installed in a UPS.

There are quite a few different chargers based on a power supply floating around the Internet. So I decided to tell you about the history of the development of my charging scheme. The scheme was created so that our catmobile would still continue to drive in the cold winter, and anyone could assemble it, more or less a radio cat. The main emphasis in the circuit design of chargers is ease of modification. In our age of “Chinization” of electronics and the electronics industry, it is often easier, cheaper and more accessible to take a ready-made AT/ATX power supply and remake it to suit any of your needs, rather than buy separately a power transformer, bridge diodes, thyristor and other parts. First, I’ll tell you about the simplest (well, it couldn’t be simpler!!!) and reliable charger based on an AT power supply, without a current indicator (although no one bothers to install an ammeter).
Well, we found a suitable AT block assembled on the TL494. We wash it, clean it, dry it and lubricate the fan.

A small digression.

About the quality of components for AT and ATX units. I want to talk about an important element of the circuit - a 310 volt filter capacitor in the primary circuit. Not only such a parameter as ripple of the output voltage with the mains frequency under heavy load depends on it, but also, which is very important, the heating of the output switches themselves. If the capacity is not enough, then they have to work up to 35% of their time at a greater pulse width than with normal capacity, since the average rectified voltage is no longer 310 volts, but 250 - 260 volts due to ripples. The controller has to handle such dips by increasing the width and open time of the transistor. Consequently, they have to operate at a higher current than with sufficient capacity. It follows from this: more current - more heating - less efficiency. (It is already small 60 - 75% depending on the block). Having carried out some measurements of older and very old AT power supplies and newer ATX, it turned out that the Chinese have completely lost their conscience. If capacitors were installed before, as it is written on it, so it was. Now the 50% tolerance is always a minus.

I went through hundreds of blocks: It says 470 MKF, you unsolder it and measure - 300 -330 MKF, even a new capacitor - the same story.
Well, okay, let them write what they want: Well, we need to replace in the AT unit, on the basis of which we will build the charging 200 MKF with these same 330 MKF, or even better, 470 MKF (the real 470). It will be easier for transistors.

It's the same story with chokes.

AT throttle: ATX throttle:

They are not finished, and the ring is smaller... The consequence of reducing the inductance of the group stabilization choke will be an acoustic whistle at low currents (1-2 amperes). The inductance of this inductor is calculated based on the continuity of the current through it at minimum loads. When the unit is turned on, it immediately reaches a power of at least 150W (depending on the computer). Certain currents flow through the inductor, no less than a certain value. The inductor can be designed for this minimum current value, but then, when turned on without a load, the current through the inductor will become intermittent, which will lead to some troubles... The PWM control circuit is designed for the case of continuous current, therefore, with intermittent current, the regulation will be go astray, the inductor will sing, the voltages at the outputs will jump, causing additional recharging currents of the electrolytic capacitors... Of course, in this case, the RC feedback correction circuit will come to our aid, but it is impossible to dull the reaction speed to voltage changes indefinitely. the torque of the TL494 during a short circuit simply will not have time to reduce the pulse width and the transistors will fail. This process is quite fast. Therefore, you need to be careful with this. Okay, that was a lyrical digression. Let's continue the "tambourine dance" with the charger.

Circuit with a soft charging current characteristic.

Standard AT block board. Let's look at the diagram to see what needs to be desoldered (and there is a lot, a lot of extra stuff that needs to be desoldered), and what to be soldered in order to get the simplest charging for the battery. The circuit is taken as a standard one, a standard AT unit, and the ratings of the already installed elements may differ significantly from yours. There is NO NEED to change them to those indicated in the diagram! We solder only the overvoltage protections that have become unnecessary, 5 volt channel, -12 volt channel. In general, according to the scheme, we leave the following.

As a result, to get a full, adjustable charging of 10 amperes and 15.8 V with a fan controlled by the load current, you need to add only eight parts!!! Namely: replace two electrolytes, add a shunt of a very approximate resistance of 0.01 ohm -0.08 ohm (for example, three centimeters of a shunt from a Chinese cartoon - it works great). Photo of the original shunt (the author's donor was taken from a Soviet Tseshka):

A 120 ohm resistor, 3.9k, and about 18k, a 10k variable resistor, a 10 nano capacitor and turn the winding on the inductor along the -5 volt channel for the fan. Just don’t forget that the fan should now be connected like this: red to the case, and black to -5:.-12V. We solder the shunt into the gap of the pigtail from the power transformer. When you set the resistor to 3.9k, select its resistance based on the charge current of 10 amperes on a real battery. You won't believe it - that's all! This is simply an unprecedented simplicity of converting practically scrap metal into a completely worthy thing! If the diodes on the +12V channel were originally FR302, then you need to replace them with more powerful ones, for example, remove them from a more modern ATX power supply. Moreover, he is not afraid of a short circuit - he is included in the current limitation. But reversing the polarity of the connection to the battery will lead to a big bang! About "KNOW-HOW", unique protection against overload and short circuit will be written in the article. Colored circles and lines indicate added additional elements.

Setting up: All switching on until complete setting is carried out by connecting it to the network only in series with a 60 watt incandescent light bulb. We check the installation.

Setting up the voltage channel.

We connect the multimeter with crocodiles in voltage measurement mode in the range of up to 200 volts. We plug it into the network. The output voltage should be within 16 volts plus/minus 4 volts. If it’s about 5 volts, it means you forgot to replace the resistor in the voltage control circuit (1 pin of TL494) with 18k. If it is about 23-25V, and the output switches gradually heat up without load, then it means that there is a break in the voltage control circuit (1 pin of TL494) or the resistance of 18k is too high, and the unit has reached the full pulse width and still cannot gain voltage to turn on the reverse communications. We set this resistor to a voltage of approximately 15.8 - 16.2 volts. If you set it to 14.4 V, then after about 1 hour the battery will stop charging at all (tested many times on different batteries).

Setting the current channel.

We temporarily replace the resistor connected in series with the current regulator with a 22k trimmer and set it to the position of minimum resistance. We connect the multimeter with crocodiles in current measurement mode in the range of 10 amperes. We connect the unit to the network through a light bulb. If the light flashes and continues to glow brightly, it means something is wrong, check the installation. If the ammeter shows a current in the range from 1 to 4 amperes, then everything is fine. We set the variable resistor to maximum resistance mode, and use the trimming resistor to adjust the current to 15 -16 amperes. Sometimes the light bulb does not allow you to set it this way, so set it to approximately this current. Now, having connected the discharged battery and the ammeter in series to the output, remove the light bulb and plug it into the network. Using a trimming resistor we adjust the current more precisely, but already 10 amperes. Then we unsolder the trimmer, measure and solder in a constant resistor of the same resistance. The cooling fan should rotate at a speed proportional to the current. If at maximum current or short the speed is too high (voltage above 20 volts), then it is necessary to unwind 10 turns from the winding minus 5 volts of the fan power channel. The voltage on the fan with selected turns should be from 6 volts to 17 volts. That's it, the setup is complete.

Hello. A friend fitted me with a board from an old AT power supply, so today we will talk about converting a computer power supply into a charger. My task is to set the output to a voltage of 14.4V and make a current regulator up to 6A. This charger is perfect for car starter batteries up to 80Ah.
The board had been collecting dust on the shelves in the garage for a long time, so the dust lay in a good layer. Some parts are missing, the board is broken in half

This is the first time I’ve seen such a convenient board for conversion into a charger. There are not many unnecessary parts, the PWM is a complete analogue of the TL494, so the modification will not take much time.

I went online in search of a suitable scheme. There are a lot of similar schemes, but the most suitable one is here.

The scheme is excellent, but you need to cut out all unnecessary things. I removed the 5V, 3V, -5-12V bus circuits, left only 12V, and also removed the PG circuit.

After the modifications, the diagram looks something like this.

And the power supply was gradually changed, repaired and modernized. Well, first of all, I cleaned the board of dirt, removed unnecessary parts and applied 15V from the 12V bus to the 12V bus. There are rectangular pulses on the isolation transformer, which means the generator is working properly.

I checked what was happening on the power transistors. The oscilloscope is weak and did not show anything criminal. For those who don’t know what kind of oscilloscope it is, read the article about it.

Well, I’ll check the power switches themselves using a multimeter.

The board was a little broken and I had to add small jumpers. Next, I wound up the old inductor and re-laid the winding 5 turns more than the 12V winding was. So far I have soldered one 25V 2200uF capacitance and replaced the resistor value according to the R30 circuit. I selected the resistor as follows: connected 14.4V to the 12V bus, measured the voltage on the second leg of 2.56V TL494, instead of R30 I put a variable 20 kOhm and by rotating it achieved 2.56V on the first PWM leg, then replaced the variable resistor with a constant one.

I put the radiator in place and found the capacitors in the box 470uF 200V in the primary circuits, I also checked the diode bridge, replaced the fuse and resistor with 1Ohm 10W. The block is ready and I hope to see 14.4V at the output.

There is already power, the lamp flashed and went out, the spiral does not illuminate and the output has the required 14.4V.

The microcircuit is powered by 24V, as it should be.

I'll try to load the nichrome spiral with 1.5 Ohm. The current at the start was 10A, but dropped to 9.4A.

With such a load, there is 14.4V on the board itself, and there are one volt less on the terminals due to the drawdown in the cable. The total power is somewhere around 150W. You can load more, but the winding is designed for approximately 5A, so I will only take 6A from the block :)
By the way, during testing a couple of times the output terminals were connected and the block went into protection. The circuit restarts after interruption of power from the 220V network; this is protection on two transistors from exceeding the permissible power.
Now you need to make a current regulator from 0 to 6A. You need to change the circuit, add 5 parts, on the table under a 6A load everything looks like this.

Completely finished board. I won’t install it in the case, I’ll put it on a shelf until a better time

Well, I’ll add a completely finished circuit after all the alterations.

15, I cut off the leg from the 5V ION and soldered the voltage from the divider to the wiring. I used a 25W 0.05 Ohm resistor as a shunt. The location of the shunt in the diagram is not very well chosen, since the current consumption of the board itself will be taken into account. To ensure that charging does not go into protection when the variable resistor is in the lowest position, a 150 Ohm resistor is soldered between the resistor and the common negative. The divider, which is powered by the middle leg of the variable resistor, sets the maximum current. That is, if 0.3V drops on a 0.05 Ohm shunt at 6A, then the 5 volt divider should result in 0.3V

This is the end of the modification, thanks for your attention. Although it would be necessary to add protection against polarity reversal here, but that's another story.

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You can assemble a charger from a computer power supply for a car battery yourself. And this unit is popular. After all, its preparation requires a minimum of funds. This results in an effective memory.

Pay attention to the condition of the car battery in winter. After all, at this time the density of the electrolytic composition changes, and the charge is quickly lost. As a result, starting the engine becomes more difficult. To solve this problem, chargers are used.

Many companies are engaged in the development and assembly of chargers for batteries. Therefore, every driver will be able to choose a model with the required parameters. Such models are distinguished by extensive functionality: training the power source, restoring charge, etc. Their cost is quite high.

Therefore, car enthusiasts are interested in a charger for a car battery, which is constructed from improvised units and elements.

Benefits of self-assembly

Use of available materials and elements. Therefore, manufacturing costs are reduced.
Light weight. It does not exceed 1.5–2 kg. Therefore, moving a homemade unit to restore battery charge is not difficult.
Constant cooling. The power supply includes a fan. Therefore, the likelihood of heating is minimal.

What are the difficulties?

The designed converter does not always operate quietly. Periodically it makes sounds that resemble ringing or hissing.
Contact between the homemade charger and the body of the vehicle is not allowed. If we charge while plugging in, the contact causes a breakdown of the converter, a short circuit.
The connection of the current-carrying terminals of the battery to the wires is carried out accurately. If errors are made at this stage, then the secondary circuits of the converted power supply into a charger fail.
All contacts and elements are checked before connection. Only after this the computer power supply is used for charging.

Rules for using a car battery

To maintain a car battery in working condition, it is not enough to prepare a reliable charger. Additionally, the following recommendations are followed:

Constant charge support. The battery source is constantly recharged. When moving, the charge comes from the generator and other components of the vehicle. If the equipment is not in use, then a charger, both stationary and portable, is used to restore the charge. If the battery is completely discharged, experts recommend rapid recovery. Otherwise, the process of sulfation of lead plates will start.
Voltage limits (about 14 V). The voltage supplied by the generator should not exceed this parameter excessively. In this case, it does not really matter which mode is running. If the motor is not functioning, the voltage can drop to 12.6–13 V. For such indicators, a charger with appropriate parameters and indicators is used.
Disconnecting consumers when the engine is not running. If the ignition is turned off, then all devices and headlights are turned off. Otherwise, the power supply will quickly lose charge.
Preparing the car battery. Before restoring the charge, electrolytic leaks and dust are removed from the battery. Conductive terminals are cleaned of oxides and deposits. Before applying voltage, connections and wires are carefully checked. After all, even minimal displacements provoke violations and problems.
In winter, the source is moved to a warm room. Indeed, at negative temperatures, the electrolytic composition becomes dense and thick. This provokes a deterioration in the passage of charge.

Main stages of memory manufacturing

Before making a reliable charger from a computer power supply, we study the safety requirements and features of working with such units. After all, there is voltage in the primary circuits of the PC power supply.

We prepare the power supply. The use of models differing in power is allowed. Most often, a computer power supply is redesigned, the power of which is 200–250 W.

After selecting a model, the following actions are performed:

The bolts are unscrewed from the computer power supply. Such actions are necessary for subsequent dismantling of the cover.
Definition of the core that is part of the pulse transformer. It is measured. The resulting value is doubled. This parameter is individual for each element. When conducting tests, it was revealed that to obtain a power of 100 W, 0.95–1 cm2 is required. After all, charging a power source is effective if it produces 60–70 W.
Many power supply models include a circuit such as the TL494. A similar scheme is included in a variety of power supplies that are offered for sale.

Preparing the circuit

To prepare a charger from a computer power supply with your own hands, certain circuit components are required (their distinctive feature is + 12V). All other elements are removed. A soldering iron is used for this. To simplify the process, we study the diagrams that are available on special portals. They depict the main elements that will be required for the power supply.

Circuits with indicators such as -12V, -/+5 V are removed. The switch that changes the voltage is also removed. The circuit that is required for the trigger signal is also soldered off.

Making a charger from a power supply is not difficult. But this will require resistors (R43 and R44), which are classified as the reference type. The values of resistor R43 change. If necessary, the output voltage changes.

Experts recommend replacing R43 with 2 resistors (variable type - R432, constant type - R431). The introduction of such resistors facilitates the process of creating an adjustable element. With its help it is easier to change the current strength, as well as the output voltage. This is required to maintain the functionality of the car battery.

When deciding how to remake the power supply, you should focus on the capacitor. A standard capacitor is concentrated at the output part of the rectifier. Craftsmen replace it with an element that has high voltage levels. So, they often use a C9 brand capacitor.

A resistor is located next to the fan, which is used for blowing. It is replaced with a resistor, which has a high resistance.

When preparing the charger for the battery, the location of the fan also changes. After all, the air mass must enter the power supply being prepared.

The tracks that are intended to connect the ground and fix the board directly to the chassis are eliminated from the circuit.

The designed power supply with regulation is connected to an alternating current network. For these purposes, a standard incandescent lamp is used (performance is 40–100 W).

Such actions are performed in order to check how effective the scheme is. Without preliminary testing, it is difficult to determine whether a power supply with a given power will burn out during sudden voltage changes.

To correctly configure the power supply for a car battery, certain rules must be followed.

Introduction of indicators. Indicators are used to monitor how charged a car battery is. Digital or dial indicators are included in the circuit. They can be easily purchased in specialized stores or dismantled from old equipment. It is possible to introduce several indicators, with the help of which the degree of charge and voltage at the conductive terminals are monitored.
Housing with fastening or handles. The presence of such a part helps to simplify the process of operating a charger from a power supply unit.

Assembling a charger from a laptop computer's power supply is permitted provided that you have some experience and knowledge in the field of electronics. It is prohibited to carry out any activities without appropriate preparation. After all, in the process you need to come into contact with conductive terminals, elements to which voltage and current are supplied.

Video about assembling a charger from a computer power supply for a car battery

Computers cannot work without electricity. To charge them, special devices called power supplies are used. They receive AC voltage from the mains and convert it to DC. The devices can deliver enormous amounts of power in a small form factor and have built-in overload protection. Their output parameters are incredibly stable, and DC quality is ensured even under high loads. When you have an extra device like this, it makes sense to use it for many household tasks, for example, by converting it from a computer power supply into a charger.

The block has the shape of a metal box with a width of 150 mm x 86 mm x 140 mm. As standard, it is mounted inside the PC case using four screws, a switch and a socket. This design allows air to flow into the cooling fan of the power supply unit (PSU). In some cases, a voltage selector switch is installed to allow the user to select the readings. For example, in the United States there is an internal power supply that operates at a nominal voltage of 120 volts.

A computer's power supply consists of several components inside: a coil, capacitors, an electronic board for regulating current, and a fan for cooling. The latter is the main cause of failure for power supplies (PS), which must be taken into account when installing a charger from an atx computer power supply.

Types of power supply for a personal computer

IPs have a certain power, indicated in watts. A standard unit is typically capable of delivering around 350 watts. The more components installed on a computer: hard drives, CD/DVD drives, tape drives, fans, the more energy is required from the power supply.

Experts recommend using a power supply that provides more power than the computer requires, as it will operate in a constant "underload" mode, which will increase the life of the machine due to the reduced thermal impact 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.

Power supply parameters that can be used when creating a charger from a computer power supply:

AT / ATX / ATX-2:+3.3 V.
ATX / ATX-2:+5 V.
AT / ATX / ATX-2: -5 V.
AT / ATX / ATX-2: +5 V.
ATX / ATX-2: +12 V.
AT / ATX / ATX-2: -12 V.

Motherboard connectors

The IP has many different power connectors. They are designed in such a way that there is no mistake when installing them. To make a charger from a computer power supply, the user will not have to spend a lot of time choosing the right cable, since it simply won’t fit in the connector.

Types of connectors:

P1 (PC/ATX connector). The main job of a power supply unit (PSU) is to provide power to the motherboard. This is done via a 20-pin or 24-pin connector. The 24-pin cable is compatible with 20-pin motherboard.
P4 (EPS socket): Previously, the motherboard pins were insufficient to support the processor power. With GPU overclocking reaching 200W, the ability to provide power directly to the CPU was created. Currently this is P4 or EPS which provides sufficient processor power. Therefore, converting the computer power supply into a charger is economically justified.
PCI-E connector (6-pin 6+2). The motherboard can provide a maximum of 75W through the PCI-E interface slot. A faster dedicated graphics card requires much more power. To solve this problem, the PCI-E connector was introduced.

Cheap motherboards are equipped with a 4-pin connector. More expensive "overclocking" motherboards have 8-pin connectors. Additional ones provide excess processor power during overclocking.

Most power supplies come with two cables: 4-pin and 8-pin. Only one of these cables needs to be used. It is also possible to split the 8-pin cable into two segments to ensure backward compatibility with cheaper motherboards.

The left 2 pins of the 8-pin connector (6+2) on the right are disconnected to ensure backward compatibility with 6-pin graphics cards. The 6-pin PCI-E connector can supply an additional 75W per cable. If the graphics card contains a single 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 provide up to 150W per cable. A graphics card with a single 8-pin connector can handle up to 225W (75W from motherboard + 150W from cable).

Molex, a 4-pin peripheral connector, is used when creating a charger from a computer's power supply. These pins are very long lasting and can supply 5V (red) or 12V (yellow) to peripheral devices. In the past, these connections were often used to connect hard drives, CD-ROM players, etc.

Even GeForce 7800 GS video cards are equipped with Molex. However, their power consumption is limited, so nowadays most of them have been replaced by PCI-E cables and all that remains are powered fans.

Accessory connector

The SATA connector is a modern replacement for the outdated 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. These were used to power floppy drives with up to 1.44 MB of data. They have mostly been replaced by USB storage today.

Molex-PCI-E 6-pin adapter for powering the video card.

When using a 2x-Molex-1x PCI-E 6-pin adapter, you must first make sure that both Molexes are connected to different cable voltages. This reduces the risk of overloading the power supply. With the introduction of ATX12 V2.0, changes were made to the 24-pin system. The older ATX12V (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 installing a charger from the computer's power supply. To ensure this, most modern sources allow you to disconnect the last 4 pins of the main connector. It is also possible to create advanced compatibility using an adapter.

Computer supply voltage

A computer requires three types of DC voltage. 12 volts is needed to supply voltage to the motherboard, graphics cards, fans, and processor. The USB ports require 5 volts, while the CPU itself uses 3.3 volts. 12 volts are also applicable for some smart fans. The electronic board in the power supply is responsible for sending converted electricity through special cable sets to power devices inside the computer. Using the above components, AC voltage is converted into pure DC current.

Almost half of the work done by a power supply is done with capacitors. They store energy that will be used for continuous work flow. When making 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 kit 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: +5V.
Blue: -12V.
White: -5V.
Orange: 3.3V.
Green, control wire for checking DC voltage.
Purple: +5V standby.

The output voltages of a computer's power supply can be measured using 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 cord plug

The hard drive wire (whether it is IDE or SATA) has four wires attached to the connector: a yellow one, two black ones in a row, and a red one. 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 12V and 5V cables at the same time.

The electrical connectors on the motherboard for processors or chassis fans have four legs that support the motherboard for 12V or 5V fans. Besides the black, yellow, and red, other colored wires can only be seen in the main connector, which goes directly into the motherboard socket. These are purple, white or orange cables that are not used by consumers to connect peripheral devices.

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 time. If you need to reconnect the power supply to the motherboard, you just need to remove the paperclip. There will be no changes in it from using a paper clip.

Procedure:

Find the green wire in the cable tree from the power supply.
Follow it to a 20 or 24 pin ATX connector. The green wire is in a sense a “receiver”, which is needed to supply energy to the power supply. There are two black ground wires between it.
Place the paperclip into 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 produce a large shock, it is not recommended to touch the metal part of the paperclip while it is energized. If you need to leave a paperclip indefinitely, you need to wrap it with electrical tape.

If you start making a charger with your own hands from a computer power supply, 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 power supply is securely disconnected, but also wear insulating gloves.

After opening the power supply, they assess the workspace and make sure that there will be no problems with clearing the wires.

They first think through the design of the source, measuring with a pencil where the holes will be in order 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 black ground wire, which will ensure that the power supply is turned on without a computer. Next you need to connect the wires to 4 large clamps, one for each set of colors.

After this, you need to group the 4-wire colors together and cut them to the required length, strip the insulation and connect them at one end. Before drilling holes, you need to take care of the chassis circuit board so that it is not contaminated with metal shavings.

Most PSUs cannot completely remove the PCB from the chassis. In this case, it must be carefully wrapped in a plastic bag. Having finished drilling, you need to treat all rough spots and wipe the chassis with a cloth to remove debris and plaque. Then install the retaining posts using a small screwdriver and clamps, securing them with pliers. After this, close the power supply and mark the voltage on the panel with a marker.

Charging a car battery from an old PC

This device will help the car enthusiast in a difficult situation when he urgently needs to charge the car battery without having 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 slightly below what is required when charging the battery. It should be 13 V, but it can be used as an emergency option. To increase the voltage where previously there was 12V, you need to change the resistor to 2.7 kOhm on the trimmer resistor installed on the additional power supply board.

Since power supplies have capacitors that store electricity for a long time, it is advisable to discharge them using a 60W incandescent lamp. To attach the lamp, use the two ends of the wire to connect to the cap terminals. 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 traces.

The procedure for making a charger from a computer power supply with your own hands begins with 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. You need to cut the output cables from the power supply using pliers. You shouldn’t throw them away; it’s better to reuse them for non-standard tasks. For each connecting post, leave no more than 4-5 cables. The rest can be trimmed 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 secured. 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 IP is small for the fixing pins. In this case, after marking the central points, you need to remove the fan.

After this, you need to attach the fixing posts to the top panel in the order: GND, +3.3 V, +5 V, +12 V. Using a wire stripper, the insulation of the cables of each bundle is removed, and the connections are soldered. Use a heat gun to heat the sleeves over the crimp connections, then insert the tabs into the connecting pins and tighten the second nut.

Next, you need to return the fan to its place, connect the 2-pin connector to the socket on the circuit board, insert the panel back into the device, which may require some effort due to the bundle of cables on the crossbars, and close it.

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 modification. 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 output 12V. Before starting work, the user must make sure that the power source 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, 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 energy supply. The color of this wire may vary, so you need to make sure it is the PS-ON signal. This should be written on the power supply sticker.

After turning on the switch, the power supply 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 produces 12 V. If so, then the screwdriver charger from the computer power supply is functioning correctly.

In fact, there are many options for adapting the power supply to your own needs. Those who like to experiment are happy to share their experiences. Here are some good tips.

Users shouldn't be afraid to upgrade the unit's box: they can add LEDs, stickers, or anything else they need to upgrade it. When disassembling the wires, you need to make sure that you are using an ATX power supply. 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 information about these wires, he should not re-equip the unit, since 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 the orange and the pink wire to the red. A high wattage power resistor may become hot. In this case, you need to use a radiator for cooling in the design.