Do-it-yourself power supply for mobile phone repair

In most cases, breakdowns of cell phones are quite easy to fix and come down to replacing the display, speaker, all kinds of cables and body elements. In the vast majority of cases, complex soldering of any elements is not required. The repair process is limited to replacing the display or a cable that connects to the cell phone circuit board via a connector. It is also quite often required to clean the cell phone circuit board from corrosion and oxides. At the same time, time-consuming soldering of microcircuits and other elements is not required.

But there are breakdowns that require the replacement of a microcircuit or the soldering of an element on the printed circuit board of a cell phone (SIM card holder, battery connector, power connector, etc.).

For successful repair of cell phones, a special tool is naturally needed. In addition, consumables are also needed, which should be on hand during the repair process.

When equipping one workplace for the service repair of cell phones, you will need several devices. Let's list them. Devices required for software repair of cell phones will not be considered.

For professional cell phone repair, of course, you need to get a soldering station. All radio elements on the cell phone board are surface-mounted, and the radio elements are extremely small. When soldering such tiny (SMD) elements, you should control the soldering temperature and try not to overheat the electronic components. The soldering temperature of electronic components should not exceed 240 0 -260 0 C. If the critical temperature is exceeded, the probability of damage to the electronic component is high.

The soldering station has all the necessary functions for working with small parts. This includes adjusting the temperature of the soldering iron tip within 200 0 - 480 0 C, digital indication of the temperature of the tip, the ability to use all kinds of tips for any work. It is also worth noting that a conventional electric soldering iron is not galvanically isolated from the mains, which increases the likelihood of damage to sensitive electronic elements on the mobile phone board. Therefore, a conventional electric soldering iron is not suitable for repairing cell phones.

There are two approaches to soldering surface mount elements (SMD, BGA). The first is hot air soldering and the second is infrared soldering. Despite the fact that infrared (IR) soldering has many advantages over hot air soldering, hot air soldering stations are more widely available. This is probably due to the fact that they have a simpler design and are several times cheaper than infrared soldering stations. It should also be noted that infrared soldering stations are more suitable for repairing motherboards of laptops and large computers.

The motherboards of computers and laptops use microcircuits that have larger linear dimensions than the microcircuits on the circuit board of cell phones, and during dismantling, uniform and larger heating of the microcircuits is required. Infrared soldering stations just have such qualities as uniform heating.

Unlike infrared soldering stations, hot air soldering stations heat the soldered element less evenly.In addition, when working with a hot air soldering station, it is necessary to monitor the flow rate of hot air. If you set too high an air flow rate, then when soldering it is easy to “blow off” neighboring elements and the heating of the element will be uneven due to the presence of hot air swirls. If you reduce the air flow rate, then the heating of the soldered part will be slower due to the fact that the still air is a heat insulator.

Despite the negative qualities of hot air soldering, hot air soldering stations are actively used in the repair of cell phones. The small dimensions of the printed circuit boards of cell phones and electronic components on them allow for high-quality assembly and disassembly of microcircuits and small-sized elements. Of course, during the repair process, it is worthwhile to correctly set the speed of hot air supply through the nozzle of the hair dryer and the air heating temperature.

Why do you need device for bottom heating of circuit boards? Oddly enough, but when repairing portable electronics - laptops, mobile phones, PDAs - the device is very necessary. The point is this.

If it is necessary to dismantle any part from the printed circuit board of the device, it is necessary to heat the element to the solder reflow temperature. Since SMT elements and BGA microcircuits are very widely used in portable electronics, when soldering with hot air, you have to warm up the microcircuit case first, and only then the contacts themselves. Naturally, heat transfer occurs from the heated microcircuit to the printed circuit board. This leads to the fact that it takes a long time to heat the soldered element, which can lead to its overheating.

In addition to overheating of electronic components, there is also the possibility of damage to the printed circuit board. With uneven heating, it begins to warp, deformation, delamination occurs. If you sharply heat the printed circuit board to a temperature of more than 280 0 C, then it will swell. In the future, it will not be possible to eliminate such deformation of the printed circuit board. For smooth and uniform heating of the printed circuit board, the bottom heating station is used.

When replacing elements such as, for example, the SIM card holder, the lower heating of the board is very convenient. Before soldering the defective latch, the printed circuit board is heated using the bottom heating station of the boards to a temperature of 120 0 - 140 0 C. In this case, the solder at the place of soldering the contacts warms up and for its final reflow, short-term soldering with hot air using a hot air gun is required. If you solder the latch only using a hot air soldering station, then prolonged exposure to hot air will deform the plastic base of the SIM card latch. It is clear that when replacing joysticks, the bottom heating station will also facilitate the work and allow it to be done more efficiently.

When restoring cell phones, you will definitely need power unit. With it, you can charge a discharged mobile phone battery or power a repaired device. In some cases, when repairing, there is a need to control the current consumed by a cell phone. Therefore, it is desirable that a built-in ammeter be present in the power supply. Preference should be given to devices with a pointer ammeter, since ammeters with digital indication are more inert.

For convenience, you can use a regular serviceable battery from any cell phone. Conductors with crocodile clips are soldered to its conclusions (there are three of them). Such a universal rechargeable battery can be used in the repair of any cell phone. The main thing is to be able to correctly connect the clamps to the power connector of the cell phone being repaired and from time to time charge such a universal battery.

In many cases, a universal power battery is enough to diagnose a malfunction of a cell phone and check its health. In this case, a stationary power supply may not be required at all.

It's no secret that one of the most common causes of mobile phone malfunctions is exposure to water. Since the cell phone is constantly on and has an autonomous power supply, even with a short exposure to water, traces of electrochemical corrosion appear on metal surfaces and contacts on the printed circuit board. The complexity of restoring the operation of “drowned” phones lies in the fact that the printed circuit board of the mobile phone is multilayer, and many microcircuits are mounted on the board using the BGA method, which makes it difficult to clean the contacts located under the microcircuit housing. Manual cleaning of the printed circuit board with special cleaning sprays or alcohol does not always lead to success and the cell phone does not always restore its functionality.

For deeper cleaning from corrosion and restoration of telephone boards - “drowned” are used ultrasonic baths (USW). Cleaning agent is poured into the ultrasonic bath. Under the action of ultrasonic waves, microbubbles appear in the liquid, which, collapsing and moving randomly, effectively clean all elements damaged by corrosion. Ultrasound accelerates chemical and physical processes, and the use of a special cleaning fluid contributes to high-quality cleaning. Using an ultrasonic bath, you can restore the operation of a seemingly hopeless cell phone.

multimeter in the workshop - this is already a classic. Any master involved in the repair of electronics always has a multifunctional tester in his workshop, with which you can measure voltage, current, resistance, and conduct “continuity” of contacts. And if the multimeter also contains a thermocouple, then they can measure the temperature of a printed circuit board or an electronic component during repair work.

This is only a tentative answer to the question of what equipment you need to have in a cell phone repair shop. Many of the listed devices will not be required immediately, but as you grow professionally and develop your business. It is also worth noting that the devices necessary for software repair are not considered here.

Do not forget that in the process of hardware repair, consumables are needed: flux, solder paste, cleaner, etc.

To begin with, it is strongly recommended that you familiarize yourself with at least the basics of radio electronics. The fact is that the repair of mobile phones is closely related to theoretical knowledge in this area. For example, if you need to replace a resistor (this is a passive current-limiting radio-electronic component), then you definitely need to know its marking, resistance, power dissipation, temperature coefficient, etc. In other owls, it is not very advisable to repair mobile phones without knowing Ohm's law. There are a huge number of books and manuals on the topic of radio electronics, as well as thematic sites on the Internet. But even this is not enough. Mobile phones are digital devices, not analog. Consequently, all parts and components used for the production of the latter have differences among themselves. For example, for analog devices, surface mount technology is mainly used, and for digital devices, surface mount technology is used. The latest technology is called SMT (surface mount technology). It is translated as "surface mount technology". And the components used in this technology are called SMD (surface mount device).

Also, in digital electronics, there is no analog signal, because. it's actually digital. Therefore, all digital devices have their own types and levels of programming. These are just a few of the differences between analog and digital technology. But even this is enough to scare off a newcomer.But there is no need to despair here. Everything is much easier than it seems. A lot of that awesome information when repairing mobile devices is not needed. But if you are planning to seriously deal with this matter, then it is strongly recommended to study analog and digital radio electronics.

Here we come to the main goal of this article. So, now you will be described in detail the procedures for the technical repair of mobile phones and the types of repair devices.

In order to repair a cell phone, including repairing Nokia, Samsung, Sony-Ericsson, LG, Motorola, the first thing is to determine the cause of the failure of the mobile device and identify the component, assembly, module or part that failed. For this, the knowledge that is described above is just needed. Typically, a breakdown of a mobile phone is caused by improper operation or loss of performance of external devices. For example, in the first case, the phone fell into the water by negligence. To restore it, complete disassembly and thorough drying is necessary. After that, you need to use a brush with soft bristles to clean the printed circuit board of the phone with a special cleaner or a 96% alcohol solution. In the second case, the LCD display, speaker, microphone, keyboard, etc. failed. As a rule, in most cases, such parts cannot be repaired and require replacement. But if there is damage to the surface (soldered) parts on the printed circuit board, then a professional approach and experience is required here. In addition, for this type of repair, you will need a diagram of nodes, modules and components of the mobile phone's printed circuit board.

In order to start the repair procedure, the phone must be disassembled.

To open a mobile phone without causing cosmetic damage to it, you need to acquire special tools for opening them. They allow you to carefully and efficiently open the phone case without causing defects. As a rule, these tools are sold in sets, each item of which is responsible for its own specific opening. Such sets are not difficult to find in specialized stores. In addition, they are of various types. The difference is between functionality and price.

You will also need a specialized set of screwdrivers for mobile phones. You don't have to save on this. The more specific number of nozzles, the more chances you will have to unscrew the screws without breaking the edges.

Next, in order to diagnose the phone for a malfunction, you will need a good digital multimeter. With it, you can measure AC and DC voltage and current, resistance, capacitance of capacitors, transistor ratio, diode condition, continuity of circuits, circuit sections or nodes, temperature. With skillful use and knowledge of some physical laws, they can find faults in the circuit. The range of multimeters is colossal. The difference usually lies in functionality and price.

We will also need a laboratory power supply or power supply. With it, you can set the specified voltage and current. You will need it very often when carrying out repair work, because. Substituting a rechargeable battery for testing, over and over again, will be inconvenient. Modern power supplies are equipped with a stabilization and current protection function, as well as a large number of various clamps and probes for various cases.

Equipment and accessories for soldering. You will need a soldering station to carry out soldering work. Their variety is infinite, and the choice is determined by price and functional range. There are combination soldering stations that combine both a heating soldering iron with temperature control and a hot air gun, which also has the function of adjusting temperature and air flow.

A hot air gun is usually necessary for mounting and dismounting SMD components, as well as integrated circuits made in a BGA package.

Also, when carrying out soldering work, you will need a device for lower heating of printed circuit boards. The fact is that when mounting or dismantling, for example, integrated circuits (chips), there is a risk of overheating and failure. When using a heating device, on which the printed circuit board of a mobile phone is placed and fixed, rational heating of the board occurs. And already when the board is heated, you can proceed to the installation or dismantling of components without fear for their breakage, because. this procedure takes a few seconds.

For soldering work, antistatic thermo-tweezers also do not hurt. With it, it is very convenient to dismantle some components.

Since you will be faced with soldering work on the installation / dismantling of integrated circuits, you will need a vacuum manipulator. This device is manual and automatic. It is designed to most accurately, efficiently and conveniently place chips with contact legs on the surface of the printed circuit board of a mobile device. It is inconvenient to do this with tweezers, all the more, there is a high probability of “killing” the microcircuit with uncalculated pressure. With a vacuum manipulator, this will never happen.

Also in the work you will need a desoldering pump. With it, you can easily desolder by removing molten solder.

Optics. Parts and components of mobile phones are measured in micrometers and nanometers. It is clear that working without special magnifying means is very problematic and harmful to vision. In these cases, it is highly recommended to get a technical microscope of 40 diopters (not to be confused with biological). You will also need an illuminated table magnifier. It is not convenient to work with a microscope in all cases, and it is convenient to use a table magnifier almost always when ultra-high magnification is not required. Mounting magnifying glasses or head binocular glasses also do not interfere.

To carry out washing, cleaning all kinds of components and printed circuit boards from dirt, oils, fats, solder, plaque and rosin, you will need an ultrasonic bath. It cleans with ultrasonics very effectively and safely.

Other tool. Among other mounting tools and accessories, you will need a mounting fixing table, with which you can easily and securely fix the printed circuit board for repair work. Be sure to have various tweezers, mounting awls, round-nose pliers, pliers, long-nose pliers, wire cutters with you. This list can be replenished with solder paste, flux, solder, rosin, cleaners, liquid for ultrasonic baths and other consumables.

Where can I get parts and components for repairs? Of course, you can buy them in specialized stores, but it's best to buy broken phones. Since in some cases, it will be very difficult to find some parts, and it will not be difficult to buy, for example, a broken phone that contains the necessary part, moreover, at a very low price.

Well, here we are with you and got acquainted with the minimum that a mobile device repair engineer should have. Of course, knowledge and experience will come with time, as theoretical and practical skills are developed. Read books on radio electronics, if possible, sign up for special training courses on mobile phone repair, communicate with people who have experience in this field, visit specialized forums on specific topics, there are always people ready to help.

In general, great success to you in your mobile phone repair business!

More information for learning how to repair mobile phones on your own HERE.

This article was born due to the fact that I had to deal with the frequent repair of cell phone chargers. Even though the price of a Chinese charger does not exceed 100 rubles (new), they are carried to me regularly. And for all their uniformity, there are slight differences in the construction of the charger circuitry.

This article will combine chargers that I copied myself and found on the Internet.

LG phone charger circuit

Another version of the charger is the so-called Frog

Let's go further

And finally, the scheme for obtaining from 12-24V at the output 4.5V 0.8A. Car adapter Panasonic Pulse, stabilized on 4 transistors.

Hello radio amateurs.
Going through old boards, I came across a couple of switching power supplies from mobile phones and I wanted to restore them and at the same time tell you about their most frequent breakdowns and troubleshooting. The photo shows two universal schemes for such charges, which are most often found:

In my case, the board was similar to the first circuit, but without the LED at the output, which only plays the role of an indicator of the presence of voltage at the output of the block. First of all, you need to deal with the breakdown, below in the photo I outline the details that most often fail:

And we will check all the necessary details using a conventional multimeter DT9208A.
It has everything you need for this. The continuity mode of diodes and transistor junctions, as well as an ohmmeter and a capacitor capacitance meter up to 200 microfarads. This set of functions is more than enough.

When checking radio components, you need to know the base of all parts of transistors and diodes, especially:

Now we are completely ready to check and repair the switching power supply. Let's start checking the block for visible damage, in my case there were two burnt resistors with cracks on the case. I did not reveal more obvious shortcomings, in other power supplies I met swollen capacitors, which also need to be paid attention first of all. Some details can be checked without desoldering, but if in doubt, it is better to desolder and check separately from the circuit. Be careful when soldering so as not to damage the tracks. It is convenient to use a third hand during the soldering process:

After checking and replacing all faulty parts, do the first switch-on through a light bulb, I made a special stand for this:

We turn on the charger through the light bulb, if everything works, then we twist it into the case and rejoice at the work done, if it does not work, we look for other shortcomings, and after soldering, do not forget to wash off the flux, for example, with alcohol. If all else fails and the nerves are on the line, throw away the board or unsolder it and take away the living parts as a reserve. Good mood everyone. I also suggest watching the video.

In the radio industry, to check or repair a cell phone, a simple power supply from a suitable charger, with an output of 6-8V 0.5-0.7A, may come in handy. To do this, we need a suitable charger from a cell phone and an LM1117 stabilizer, or the like. You can find these stabilizers on motherboards, video cards and various Chinese devices. And you can get hold of the boards themselves in computer repair shops, where they are simply thrown away.

Previously, I already laid out a similar alteration of the memory, you can see it here:
https://my.housecope.com/wp-content/uploads/ext/2533/forum/3-3792-2 post 16.

We assemble a voltage regulator on a miniature seal and set the 4V output with a resistor R1.
If space in the memory allows, you can solder a small heat sink, it will not hurt. Then we build the scarf into any free place in the memory, and for greater safety it can be put on heat shrink.

We remove the old cord and drill out the adapter block and insert a suitable one with thicker wires. We solder mini crocodiles or mini clips like mine, if any, to them.

As a result, we get a simple power supply for checking or repairing cell phones.Moreover, the block can be useful for the initial charge of completely dead lithium batteries (their rise), for the subsequent full charge. For this, a small heat sink is useful in the block, because. the stabilizer in this application will warm up a little ..
Good luck with the repair..

Somehow I decided to create a normal power source,
shoveled through the entire archive of Radio magazines, but did not find the scheme I needed,
either the element base was not suitable, or the circuits were very cumbersome and did not meet the requirements.
And now, a miracle, I came across this scheme and picked up details that were more or less suitable for the characteristics of the parts used in the scheme.
VT1-kt315, vt2-kt801, vt3-kt361, vt4-kt805 (these were previously used in the output stage of the vertical scanning of 3ust TVs)
we put it on the radiator. I made a rectifier using a bridge circuit on 1n4007 diodes, an electrolyte at 4700 microfarads and a film at 0.1 microfarads.
The device does not need to be configured and, with proper installation and assembly, it starts working immediately. It works for me in the range from 0 to 15 volts.

P.S. Gentlemen, sorry for the photo, I made it with a mobile phone in haste)))

And what box to fill in SAMSUNG GDFS from NOKIA

For thanks there is a special BUTTON and do not forget to put + for useful messages.
UFS,RIFF-box,SeTool,Mx-box,ATF,Z3X-box.

Voltage from 1.7 volts to 15 volts smoothly, with current stabilization 0-1.2A adjustable or 1A fixed.

The voltage is automatically set to the desired value when the connector is plugged into the power supply (we prepare a set of cords with connectors from different phones, plugged in, the power supply itself set the required voltage). Two-stage protection, current stabilization at the set value and opening of the circuit when the voltage in the channel drops below 1.5 volts (such a drop indicates that either the polarity is reversed or the semiconductor is knocked out in the fed circuit or a short circuit in the terminals). Open circuit protection works as follows. After the protection is triggered, the unit lights up the alarm LED, briefly beeps, waits for 10 seconds and then breaks the circuit and enters the standby mode for manual reset of the protection. Return to work after pressing the reset button.
There is also a sound signaling of current stabilization operation (both the beginning and the end), short “ticks” of different tonality for both cases.

Ammeter for two ranges, 600mA and 1.2A, with automatic range selection.

The voltmeter is the same as in the photo above (in the second photo, the voltmeter measurement channel selection switch is visible on top of the voltmeter head).

I also made an external unit to use the channel as a laboratory one. It has the usual terminals, alternators for adjusting the current, voltage and a pair of toggle switches (the voltage is fixed five volts and adjustable and switching the transformer windings for voltage at the channel output up to seven volts and up to fifteen).

Adjustable, with step voltage change. Values ​​are 2.8V, 3V, and 3.6 to 4.3V in 0.1 Volt steps. Open circuit protection with a threshold of 0.5A and 1.2A with a rated response time. In fact, when the mobile phone is working, the protection does not work in the transmission mode, even if the protection is reduced to a threshold of 200 mA. At the same time, an error with reversed polarity does not lead to fatal consequences, because the protection works faster than it takes the capacitor to “crookedly” charge by Vbat to a voltage of one volt.

The protection logic is simple, when the protection current exceeds the set threshold, it breaks the circuit. An audible signal sounds and the LED flashes. After five seconds, the protection is reset. If the protection worked three times in a row, the attempts stop. Exit the state with the red button. If the protection has not worked, pressing and holding the same button (approximately two seconds) leads to a break in the circuit for five seconds.

The current indicator is pointer, with limits of 100mA, 500mA and 1A, with autorange selection and dynamic LED (visible on the head of the voltmeter to the right of the display). Dynamic allows you to visually observe the dynamics of current consumption during the operation of the phone (you can see how the processor reads blocks from a flash or pulls devices on the I2C bus when it is turned on. When flashing, it’s a fairy tale in general, everything can be seen how it erases the page, writes, verifies

The view turned out of course not so hot, the case is small, it was not possible to logically arrange all the controls. Although it is convenient to use. And it takes up little space on the table.

I will not provide a diagram. for it is an obese arctic fox in the third stage. I can only say that the density and quantity of contents turned out to be such that a box of 130-190-60 in size turned out to weigh almost three kilograms. And don't stick your finger inside.

In multiples, the stabilizer is made on AZ1084ADJ (type LM317 but with a low voltage drop) with supporters on TL431 (gives good voltage stability over time and temperature). The rest is the op amp OP07 as a current sensor amplifier, UD6 in the current stabilizer and several LM324 as terminations and comparators. And a bunch of 74 logic to ensure the protection, because I had to look for a scrap programmer from microcontrollers. In general, there is nothing that would not be found in Hill and Horowitz's IP.

Perhaps the most "sick" part of a cell phone is its charger. A compact DC source with an unstable voltage of 5-6V often fails for various reasons, from the actual malfunction to mechanical failure as a result of careless handling.

However, it is very easy to find a replacement for a faulty charger. As an analysis of several chargers from various manufacturers showed, they are all built according to very similar schemes. In practice, this is a circuit of a high-voltage blocking generator, the voltage from the secondary winding of the transformer of which is rectified and serves to charge the battery of a cell phone. The difference usually lies only in the connectors, as well as minor differences in the circuit, such as the implementation of the input mains rectifier in a half-wave or bridge circuit, the difference in the operating point setting circuit based on the transistor, the presence or absence of an indicator LED, and others little things.

And so, what are the "typical" malfunctions? First of all, you should pay attention to the capacitors. The breakdown of the capacitor connected after the mains rectifier is very likely, and leads both to damage to the rectifier and to the burnout of a low-resistance constant resistor connected between the rectifier and the negative plate of this capacitor. This resistor, by the way, works almost like a fuse.

Often the transistor itself fails. Usually there is a high-voltage power transistor, designated "13001" or "13003". As practice shows, in the absence of such a replacement, you can use the domestic KT940A, which was widely used in the output stages of video amplifiers of old domestic TVs.

The breakdown of the 22 uF capacitor leads to the absence of generation start. And damage to the 6.2V zener diode leads to unpredictable output voltage and even failure of the transistor due to overvoltage at the base.
Damage to the capacitor at the output of the secondary rectifier is the least common.

The design of the charger case is non-separable. You need to saw, break: and then somehow glue it all together, wrap it with electrical tape. There is a question about the feasibility of repair. Indeed, in order to charge a cell phone battery, almost any source of direct current with a voltage of 5-6V, with a maximum current of at least 300mA, is sufficient. Take such a power supply, and connect it to the cable from the faulty charger through a 10-20 ohm resistor. And that's it. The main thing is not to reverse the polarity. If the connector is USB or universal 4-pin, turn on the resistance of about 10-100 kilo-ohms between the middle contacts (choose it so that the phone “recognizes” the charger).

The article talks about a typical malfunction of mobile phone chargers.A diagram of one of these blocks, compiled according to a "live" model, is given, recommendations are given for changing the output parameters and using the repaired block in amateur radio practice.

The culprit was the zener diode, conditionally indicated in the diagram of Fig. 1 by the number 7. It had a leak and “floating” parameters.
The free space in the power supply housing made it possible to use a chain of several series-connected domestic zener diodes instead. At the same time, it was easy to obtain other, except for the passport, values ​​of the output voltage (see table).
This will probably be of interest to radio amateurs, since they will always find use for such a powerful and small-sized power supply. The location of the elements on the board is shown in Fig.2.

The diagram below is for MC34063A allows you to charge your iPod without connecting it to a computer. Using the computer's USB port to charge the battery is not always practical. For example, there is no computer at hand or there is no need to turn it on due to charging. Chargers for mobile phones, iPods and MP3 players are available, but they are expensive and you need separate options for charging at home and in the car.

On a long hike (walking or cycling) you can not do without lighting. Flashlights that are recharged from the mains are not enough for a long time, and tourist routes pass mainly in places where there are no power lines. The charger "Tourist" will help to solve this problem. Read more…

I wanted to collect some kind of battery charger. And the very first thing I thought to assemble was protection against polarity reversal on the relay. The simple scheme below for protecting the charger and battery is within the power of anyone, even a novice radio amateur. Read more…

Fuel-free generator - mobile phone charger.

A small description of the video, which demonstrates the operation of a fuel cell running on ethyl alcohol.

The article describes the design of a simple triac power controller for controlling incandescent lamps and LED lamps designed to be controlled using dimmers. It also tells about the experience of repairing factory dimmers manufactured by Leviton.

This article describes the design of a homemade portable charger designed to power or charge the batteries of players, mobile phones and smartphones that are compatible with the USB interface.

The difference between this power supply unit and similar ones is that it controls its own switching on and off, both in the mode of charging its own batteries, and in the mode of energy return.

About the sources of cheap lithium-ion batteries and how to disassemble the battery from a laptop for repair or to remove the batteries for reuse.

For a long time I dreamed of making a battery for my M890C + and DT-830B multimeters from an ordinary 9-volt Krona battery. And finally, the turn has come to this homemade product.

This article is about how to convert a Krona battery into a battery using a minimum number of parts.

This article is about how to assemble the simplest power regulator for a soldering iron or other similar load. https://my.housecope.com/wp-content/uploads/ext/1284/

The circuit of such a regulator can be placed in a power plug or in a case from a burnt out or unnecessary small-sized power supply. It will take an hour or two to assemble the device.

This article describes how to calculate and wind a pulse transformer for a homemade half-bridge power supply, which can be made from the electronic ballast of a burned-out compact fluorescent light bulb.

It's about "lazy winding". This is when too lazy to count the turns. https://my.housecope.com/wp-content/uploads/ext/1284/

In this article you will find a detailed description of the manufacturing process of switching power supplies of different capacities based on the electronic ballast of a compact fluorescent lamp.

You can make a switching power supply for 5 ... 20 watts in less than an hour. It will take several hours to manufacture a 100-watt power supply. https://my.housecope.com/wp-content/uploads/ext/1284/

Building a power supply will not be much more difficult than reading this article. And certainly, it will be easier than finding a low-frequency transformer of suitable power and rewinding its secondary windings to fit your needs.

This publication continues a series of articles on the construction of an amateur low-frequency amplifier.

The article describes the design of a power supply assembled from available parts and designed to power a stereo amplifier with a power of 10 watts per channel.

Articles are written as a particular block is made. https://my.housecope.com/wp-content/uploads/ext/1284/

Next in line is the regulator block and the final amplifier block.