Powerful DIY phone charger. Do-it-yourself wireless charging for your phone

Greetings, dear readers. In today’s article, we’ll talk about today’s hot technology – wireless charging for phones. You've probably heard how branded companies focus on it when introducing the next portable device with its support. Not wanting to spend their hard-earned money, many remain with their old mobile phone, never ceasing to dream of trying out wireless charging.

Do-it-yourself wireless charging is very simple and sufficient fast decision. Read the instructions and watch the video. Interesting, right? Then let's go in order. But be sure to read the advice at the end of the article!

Something new? No, the long-known “old”

When I first saw wireless charging, I thought that manufacturers had made a breakthrough by opening some kind of new technology. Fortunately, there is the Internet, which told me the truth. In fact, the advent of wireless energy transmission was made possible by the discovery of André Marie Ampere's law, which proved that electric current produces a magnetic field.

And this happened, for a moment, almost 200 years ago. In subsequent years, a number of scientists confirmed the existence of electromagnetic waves, and Nikola Tesla devoted years of his life to studying the possibility of transmitting energy over a distance. Using electromagnetic induction, the physicist was able to light an incandescent lamp from a distance.

Standard Qi

Of course, wireless energy transfer was of interest to many areas of human life, but for a long time it did not go beyond the walls of laboratories. Already in this century, companies that develop consumer electronics (tablets, smartphones) began to take initiatives to create wireless chargers. The Wireless Consortium made a huge contribution electromagnetic energy(Wireless Power Consortium), which developed the Qi standard for low currents.

The standard specification was free and accessible, so it very soon began to be used in portable equipment. Three years later, Qi acquired a specification for medium currents. There are other standards, but they are more complex than Qi and less common. More recently, in 2015, scientists at the University of Washington discovered that energy can be transmitted via Wi-Fi networks. We are waiting for the smartphone to charge by connecting to the router.

How Qi wireless charging works

Well, already from the name of the device it becomes clear that the gadget does not require connecting wires to transfer energy. The operating principle is very simple. The charger has a built-in coil (copper), which takes on the role of creator and transmitter of the electromagnetic field already on the receiver coil placed in the smartphone (can be above the battery or back cover). Electromagnetic radiation occurs when mobile phone with the receiver placed in close proximity to the transmitter (usually about 4 centimeters). Then the capacitors and rectifier (low-power semiconductor diode) get to work, which provide the battery with energy.

So, can I do wireless charging myself?

Yes, this doesn’t even require any special knowledge of electrical engineering. Moreover, enthusiasts had already conducted similar experiments before us, posting detailed instructions and diagrams for assembling wireless charging with your own hands. If all the necessary components are at hand, then creating the simplest wireless charging will not take even an hour. However, we recommend that you first practice on old “push-button” devices, and not rush to “invent” charging for a brand new iPhone. For example, you can assemble such a thing for your Nokia, whose charging socket has fallen off, resuscitating it in this way. So let's get started.

Instructions: how to make wireless charging for your phone with your own hands

The whole process can be divided into two parts: manufacturing the transmitter and the receiver. The first component will be a separate device, and the second will be installed on the phone.

The wireless charging circuit is very simple, consisting of two coils (transmitter and receiver), as well as a transistor and resistor.

Transmitter device:

1. To begin with, we take a frame, the diameter of which should be 7-10 centimeters, but you can have another one - at your discretion.
2. Now you will need copper wire with a diameter of 0.5 mm. This is what we wrap around the frame. It is necessary to make 20 turns, then make a tap and twist another 20 turns in the opposite direction.
3. You will need a transistor. You can use any, be it polar or bipolar - there is not much difference. If there is direct conduction, then you will have to change the polarity. The transistor is connected to the end of the coil and the tap.
4. We fasten the resulting structure with tape or another type of insulation. To make everything look “solid”, you can use DVD or CD boxes. Some craftsmen even bother cutting out, so to speak, wooden bodies.
5. To provide power, you can use a standard 5 Volt power adapter that connects to the circuit.
6. Everything, the device that will transmit electricity is ready.

Now let's move on to making the receiver:

1. If making a transmitter takes a few minutes, then you will have to work hard with the receiver. First you have to make a coil, but a flat one. You will need copper wire, but with a smaller diameter - 0.3-0.4 mm. You will need to make 25 turns. For convenience, I advise you to use some kind of lining, for example a piece of plastic. We gradually strengthen the coils with superglue so that the structure does not fall apart - you will have to wind it again. At the end of the work, you must carefully tear the receiver away from the plastic on which it was wound.
2. Now we connect our receiver to the battery via a high-frequency silicon diode, for example SS14. The coil should be on the top of the battery, closer to the cover. To stabilize the voltage, a capacitor should be used.
3. You can connect the receiver either to the charging connector or directly to the battery. Last option Great suitable for users, whose charging port “died”.
4. That's it, we're closing back cover so as not to move the coil.

For many users, I think a video on how to make wireless charging with your own hands would be helpful. So here you go:

With this, your DIY wireless charger is ready. To start using it, just place your phone on the transmitter. To date, more than a dozen instructions for assembling wireless chargers have accumulated on the Internet. The principle is approximately the same, but enthusiasts continue to improve this device, introducing something of their own. True, it is better for beginners to practice first simple version, presented in the instructions, so that you do not have to take the phone for repair.

Suitable for any device

The most important advantage of DIY wireless charging is the ability to make it for almost any device: smartphone, regular phone, camera, radio, and so on. The power principle of all these gadgets is similar, so charging follows the same scenario.

True, I strongly do not recommend trying to make wireless charging with your own hands for expensive smartphones. Firstly, you will have to disassemble the case in order to connect the receiver coil, since modern models are often made non-separable (it is not possible to simply remove the cover). Secondly, if you mix something up, you risk damaging the device, especially for beginners. Thirdly, most modern smartphones support wireless charging from the factory or provided by other manufacturers.

Disadvantages of DIY wireless charging

Smoothly we come to a very important point - the disadvantages of homemade wireless chargers. Yes, the opportunity to make an interesting and useful device at no extra cost is great, but let’s not forget about the risks you are taking.

• Errors during manufacturing will, at best, lead to the fact that wireless charging will not work; at worst, the phone will not work.
• Don't expect your smartphone to charge quickly. Even factory wireless chargers still lag behind conventional chargers in terms of charging speed, let alone those made by yourself.
• I don’t think that every house has a coil of wire, a diode and a couple of transistors. You will have to buy all this, spending an amount comparable to that required to buy a ready-made, albeit Chinese, device.

What can I add? Do-it-yourself wireless charging is more of a way to visually look at the principle of operation of the electromagnetic field. To assemble a truly worthwhile and beautiful device, you will need to spend a lot of time and money. It is more profitable to order a ready-made kit without wasting time on winding the circuit. Of course, if you are a fan of creating something unusual with your own hands, then be sure to start developing “your own” wireless charger.

What should those who don’t want to spend time assembling wireless charging do it themselves? It’s simple - we order a ready-made kit, which is already more or less well assembled at the factory. The cost, as a rule, does not exceed 300 rubles, and the kit already includes both a transmitter and a receiver. Wireless chargers are sold in electronics stores, but it is more profitable to order from Chinese online stores.

Please note that many modern smartphones are equipped by the manufacturer with a receiver (receiver). Therefore, owners of these models do not need to purchase anything additional (in exceptional cases, sellers may not include a docking station (transmitter) in the kit). The list of such devices is quite extensive:

• Samsung (Note 5, S6/S6 Duos and later models)
• Google Nexus 4/5/6/7
• LG G3 and new flagships
• Blackberry 8900
• Nokia Lumia (810-930)
• Yotaphone 2

The list includes the most common models, but not all. In addition, it is regularly updated with new devices. To find out if your smartphone supports wireless charging, look for the “Qi” designation in the model specifications. Information must also be present on the manufacturer’s website.

My smartphone does not support wireless charging

If your device does not have a built-in receiver, do not rush to get upset - Chinese “friends” have taken care of users by releasing both special receivers for certain models and universal receivers. About the first type, I think everything is clear. Usually, they indicate which smartphone model it is intended for. But the second type of receiver is more interesting. Such receivers are not tied to a specific smartphone, so they can be installed in almost any one. However, it should be taken into account that universal receivers are divided into several classes:

• Film with special contacts. Fits under the phone cover without affecting functionality. The device must have contacts near the battery for its installation. The main advantage is that the charging socket remains free.
• Apple receiver. This type is intended for Apple devices with a Lightning connector, that is, all current models.
• Android receiver. Designed for smartphones with a microUSB connector. Since there are plenty of Android smartphones, and the manufacturer places the charging socket however he wants (and where he wants), you should look at the specific model. As a rule, microUSB is located on the lower or upper end, and is of type “A” (connector in the form of a regular trapezoid, when looking at the smartphone with the screen up), “B” (irregular trapezoid) or “C” (oval).

The docking station (transmitter) does not play a special role - you can even use more than one kit or a completely different form. Therefore, the receiver and charging pad can be purchased separately, which will help save a little more.

In addition to receivers that need to be mounted on a lid or hidden under it, cases with a built-in receiver are available for sale. Of course, they are not universal, so you can’t find one for every smartphone. And they don't look the best. Be that as it may, many may still be interested in this look.

Models of ready-made wireless chargers

So, we come to buying a wireless charger from Chinese online sites. You can, of course, go to an electronics store that sells better models, but you will have to pay significantly more. Therefore, we go to one of the stores on the Internet, where we look for something like “universal wireless chargers.” Here you will meet a bunch of models. Then you have several options:

• Purchasing a complete set. In this case, you get both a receiver (receiver) and a charging pad. Upon receipt, all you have to do is connect everything.
• Purchasing parts separately. Perhaps you already have a receiver, but the docking station is broken (or vice versa). In order not to waste money, you can order only what you need.
• Purchasing components for self-assembly. Some sellers provide the base (coils, boards, transistors, etc.) so that the user can assemble whatever his heart desires.

You can’t single out popular companies because sellers don’t even list them. And if the manufacturer is indicated, then the name says absolutely nothing (some kind of Chinese company). And it’s stupid to bother finding a good manufacturer - the cost of wireless charging is usually ridiculous. Plus, customer reviews indicate that the defect rate is quite low.

Making your own solar USB charger for your phone is one of the most interesting and useful projects on. Making a homemade charger is not too difficult - the necessary components are not very expensive and are easy to obtain. Solar chargers USB devices and are ideal for charging small devices, such as a phone.

The weak point of all homemade solar chargers is the batteries. Most are assembled on the basis of standard nickel-metal hydride batteries - cheap, accessible and safe to use. But unfortunately, NiMH batteries have too low voltage and capacity to be seriously considered in quality, the energy consumption of which is only growing every year.

For example, the iPhone 4's 2000 mAh battery can still be fully recharged from a homemade solar charger with two or four AA batteries, but the iPad 2 is equipped with a 6000 mAh battery, which is no longer so easy to recharge using a similar charger.

The solution to this problem is to replace nickel-metal hydride batteries with lithium ones.

From this instruction you will learn how to make a solar USB charger with a lithium battery with your own hands. Firstly, compared to this, a homemade charger will cost you very little. Secondly, it is very easy to assemble. And most importantly, this lithium USB charger is safe to use.

Step 1: Required components to assemble the solar USB charger.

Electronic components:

• 5V or higher solar cell
• 3.7V Li-ion battery
• Li-ion battery charging controller
• USB DC boost circuit
• Panel mount 2.5mm jack
• 2.5 mm jack with wire
• Diode 1N4001
• The wire

Construction materials:

• Insulating tape
• Heat shrink tubing
• Double Sided Foam Tape
• Solder
• Tin box (or other enclosure)

Tools:

• Soldering iron
• Hot glue gun
• Drill
• Dremel (not required, but recommended)
• Wire cutters
• Wire stripper
• Help from a friend

This tutorial shows you how to make a solar powered phone charger. You can refuse to use solar panels and limit yourself to making a regular USB charger using lithium-ion batteries.

Most of the components for this project can be purchased at online electronics stores, but the USB DC boost circuit and lithium-ion battery charge controller will not be so easy to find. Later in this guide, I'll tell you where you can get most of the required components and what each of them does. Based on this, you can decide for yourself which option suits you best.

Step 2: Benefits of lithium battery chargers.

You may not realize it, but most likely a lithium-ion battery is in your pocket or on your desk right now, or maybe in your wallet or... Most modern electronic devices use lithium-ion batteries, characterized by high capacity and voltage. They can be recharged many times. Most AA batteries are nickel-metal hydride in chemical composition and cannot boast of high technical characteristics.

From a chemical standpoint, the difference between a standard AA NiMH battery and a Lithium-Ion battery lies in the chemical elements contained within the battery. If you look at the periodic table of elements, you will see that lithium is in the left corner next to the most reactive elements. But nickel is located in the middle of the table next to chemically inactive elements. Lithium is so reactive because it only has one valence electron.

And it is precisely for this reason that there are many complaints about lithium - sometimes it can get out of control due to its high chemical reactivity. Several years ago, Sony, a leader in laptop battery production, produced a batch of low-quality laptop batteries, some of which spontaneously caught fire.

This is why when working with lithium-ion batteries, we must take certain precautions - very accurately maintain the voltage during charging. This instruction uses 3.7 V batteries, which require a charging voltage of 4.2 V. If this voltage is exceeded or decreased, the chemical reaction can get out of control with all the ensuing consequences.

This is why extreme caution must be exercised when handling lithium batteries. If you handle them carefully, they are quite safe. But if you do inappropriate things with them, it can lead to big trouble. Therefore, they should be used only strictly according to the instructions.

Step 3: Selecting a lithium-ion battery charge controller.

Due to the high chemical reactivity of lithium batteries, you must be one hundred percent sure that the charge voltage control circuit will not let you down.

Although you can make your own voltage control circuit, it is better to simply buy a ready-made circuit that you will be confident in its performance. There are several charge control schemes available to choose from.

On this moment Adafruit is now in its second generation of charge controllers for lithium batteries with several available input voltages. These are pretty good controllers, but they are too large. It is unlikely that it will be possible to assemble a compact charger using them.

You can buy small lithium battery charging controller modules on the Internet, which are used in this manual. Based on these controllers, I also assembled many others. I like them for their compactness, simplicity and LED battery charge indicator. As with Adafruit, when there is no sun, the lithium battery can be charged via the controller's USB port. The ability to charge via a USB port is an extremely useful option for any solar charger.

Regardless of which controller you choose, you should know how it works and how to operate it correctly.

Step 4: USB port.

Most modern devices can be charged via the USB port. This is the standard all over the world. Why not just connect the USB port directly to the battery? Why do you need a special circuit for charging via USB?

The problem is that the USB voltage is 5V, but the lithium-ion batteries we will be using in this project are only 3.7V. So we will have to use a USB DC boost circuit that increases the voltage to enough to charge various devices. Most commercial and homemade USB chargers, on the contrary, use step-down circuits, since they are assembled on the basis of 6 and 9 V batteries. Step-down circuits are more complex, so it is better not to use them in solar chargers.

The scheme used in this manual was chosen as a result of lengthy testing of various options. It's almost identical to Adafruit's Miniboost circuit, but costs less.

Of course you can buy an inexpensive USB charger online and take it apart, but we need a circuit that converts 3V (the voltage of two AA batteries) to 5V (the voltage on the USB). Disassembling a regular or car USB charger will not do anything, since their circuits work to reduce the voltage, but on the contrary, we need to increase the voltage.

In addition, it should be noted that the Mintyboost circuit and the circuit used in the project are capable of working with Apple gadgets, unlike most other USB charging devices. Apple devices check the information pins on the USB to know where they are connected. If the Apple gadget determines that the information pins do not work, then it will refuse to charge. Most other gadgets do not have such a check. Believe me - I tried many cheap charging circuits from eBay - none of them managed to charge my iPhone. You don’t want your homemade USB charger to be unable to charge Apple gadgets.

Step 5: Battery selection.

If you Google a little, you will find a huge variety of sizes, capacities, voltages and prices. At first, it will be easy to get confused in all this diversity.

For our charger we will be using a 3.7V lithium polymer (Li-Po) battery, which is very similar to an iPod or cell phone battery. Indeed, we only need a 3.7 V battery, since the charging circuit is designed for this voltage.

The fact that the battery should be equipped with built-in protection against overcharge and overdischarge is not even discussed. This protection is usually called "PCB protection". Search eBay for these keywords. It is just a small printed circuit board with a chip that protects the battery from overcharging and discharging.

When choosing a lithium-ion battery, look not only at its capacity, but also at its physical size, which mainly depends on the case you choose. I used an Altoids tin box as the case, so I was limited in my choice of battery. At first I thought of buying a 4400 mAh battery, but due to its large size, I had to limit myself to a 2000 mAh battery.

Step 6: Connecting the solar panel.

If you are not going to make a charger that can be recharged from the sun, you can skip this step.

This tutorial uses a 5.5V, 320mA hard plastic solar cell. Any large solar panel will work for you. For the charger, it is best to choose a battery designed for a voltage of 5 - 6 V.

Take the wire by the end, divide it into two parts and strip the ends a little. A wire with a white stripe is negative, and an all-black wire is positive.

Solder the wires to the corresponding contacts on the back of the solar panel.

Cover the solder joints with electrical tape or hot glue. This will protect them and help reduce stress on the wires.

Step 7: Drill the tin box or housing.

Since I used an Altoids tin as the body, I had to do a little drill work. In addition to the drill, we will also need a tool such as a dremel.

Before you start working with a tin box, put all the components in it to make sure in practice that it suits you. Think about how best to place the components in it, and only then drill. You can mark the locations of the components with a marker.

After designating the places, you can get to work.

There are several ways to remove the USB port: make a small cut right at the top of the box, or drill a hole of the appropriate size on the side of the box. I decided to make a hole on the side.

First, attach the USB port to the box and mark its location. Drill two or more holes inside the designated area.

Sand the hole with the Dremel. Be sure to follow safety precautions to avoid injuring your fingers. Do not hold the box in your hands under any circumstances - clamp it in a vice.

Drill a 2.5mm hole for the USB port. If necessary, widen it using a Dremel. If you don't plan to install a solar panel, then the 2.5mm hole is not necessary!

Step 8: Connecting the charging controller.

One of the reasons I chose this compact charge controller is its reliability. It has four contact pads: two in front next to the mini-USB port, where constant voltage is supplied (in our case from solar panels), and two in the back for the battery.

To connect a 2.5 mm connector to the charging controller, you need to solder two wires and a diode from the connector to the controller. In addition, it is advisable to use heat-shrinkable tubing.

Fix the 1N4001 diode, charge controller and 2.5mm jack. Place the connector in front of you. If you look at it from left to right, the left contact will be negative, the middle one will be positive, and the right one is not used at all.

Solder one end of the wire to the negative leg of the connector, and the other to the negative pin on the board. In addition, it is advisable to use heat-shrinkable tubing.

Solder another wire to the diode leg, next to which there is a mark. Solder it as close to the base of the diode as possible to save more space. Solder the other side of the diode (without the mark) to the middle pin of the connector. Again, try to solder as close to the base of the diode as possible. Finally, solder the wires to the positive contact on the board. In addition, it is advisable to use heat-shrinkable tubing.

Step 9: Connecting the battery and USB circuit.

At this stage, you only need to solder four additional contacts.

You need to connect the battery and USB circuit to the charge controller board.

First cut some wires. Solder them to the positive and negative terminals on USB circuit, which are located on the bottom side of the board.

After that, connect these wires together with the wires coming from the lithium-ion battery. Make sure you connect the negative wires together and connect the positive wires together. Let me remind you that the red wires are positive and the black wires are negative.

Once you have twisted the wires together, weld them to the terminals on the battery, which are on the back of the charge controller board. Before soldering, it is advisable to thread the wires into the holes.

Now we can congratulate you - you have 100% completed the electrical part of this project and can relax a little.

At this stage, it is a good idea to check the functionality of the circuit. Since all electrical components are connected, everything should work. Try charging your iPod or any other gadget equipped with USB port. The device will not charge if the battery is low or defective. In addition, place the charger in the sun and see if the battery will charge from the solar panel - the small red LED on the charge controller board should light up. You can also charge the battery via a mini-USB cable.

Step 10: Electrically isolate all components.

Before placing all the electronic components in the tin box, we must be sure that it cannot cause short circuit. If you have a plastic or wooden case, then skip this step.

Place several strips of electrical tape on the bottom and sides of the tin box. It is in these places that the USB circuit and charging controller will be located. The photographs show that my charging controller was left loose.

Try to carefully insulate everything so that a short circuit does not occur. Make sure the solder joints are secure before applying hot glue or tape.

Step 11: Placing the Electronic Components in the Case.

Since the 2.5mm jack needs to be secured with bolts, place it first.

My USB circuit had a switch on the side. If you have the same circuit, then first check whether the switch that is needed to turn the “charging mode” on and off works.

Finally, you need to secure the battery. For this purpose, it is better to use not hot glue, but several pieces of double-sided tape or electrical tape.

Step 12: Operate your homemade solar charger.

In conclusion, let's talk about the correct operation of a homemade USB charger.

You can charge the battery via a mini-USB port or from the sun. The red LED on the charge controller board indicates the charging process, and the blue LED indicates a fully charged battery.

We looked at the circuit of a simple autonomous charger for mobile equipment, working on the principle simple stabilizer with a decrease in battery voltage. This time we will try to assemble a slightly more complex, but more convenient memory. The batteries built into miniature mobile multimedia devices usually have a small capacity, and, as a rule, are designed to play audio recordings for no more than several tens of hours when the display is turned off, or to play several hours of video or several hours of reading e-books. If a power outlet is unavailable or the power supply is turned off for a long period of time due to bad weather or other reasons, then various mobile devices with color displays will have to be powered from built-in energy sources.

Given that such devices consume considerable current, their batteries may be discharged before electricity is available from a wall outlet. If you do not want to immerse yourself in primitive silence and peace of mind, then to power your handheld devices, you can provide a backup autonomous energy source, which will help out both during a long journey into the wild, and in case of man-made or natural disasters, when your settlement may be on the verge of destruction. several days or weeks without power supply.

Mobile charger circuit without 220V network

The device is linear stabilizer compensation type voltage with low saturation voltage and very low intrinsic current consumption. The energy source for this stabilizer can be a simple battery, accumulator battery, solar or manual electric generator. The current consumed by the stabilizer when the load is off is about 0.2 mA at an input supply voltage of 6 V or 0.22 mA at a supply voltage of 9 V. The minimum difference between the input and output voltage is less than 0.2 V at a load current of 1 A! When the input supply voltage changes from 5.5 to 15 V, the output voltage changes by no more than 10 mV at a load current of 250 mA. When the load current changes from 0 to 1 A, the output voltage changes by no more than 100 mV at an input voltage of 6 V and by no more than 20 mV at an input supply voltage of 9 V.

A self-resetting fuse protects the stabilizer and battery from overload. The reverse-connected diode VD1 protects the device from reverse polarity of the supply voltage. As the supply voltage increases, the output voltage also tends to increase. To maintain the output voltage stable, a control unit assembled at VT1, VT4 is used.

An ultra-bright blue LED is used as a reference voltage source, which, while performing the function of a micro-power zener diode, is an indicator of the presence of output voltage. When the output voltage tends to increase, the current through the LED increases, the current through the emitter junction VT4 also increases, and this transistor opens more, and VT1 also opens more. which bypasses the gate-source of the powerful field-effect transistor VT3.

As a result, the resistance of the open channel of the field-effect transistor increases and the voltage across the load decreases. Trimmer resistor R5 can be used to adjust the output voltage. Capacitor C2 is designed to suppress self-excitation of the stabilizer as the load current increases. Capacitors C1 and SZ are blocking capacitors in the power supply circuits. Transistor VT2 is included as a micro-power zener diode with a stabilization voltage of 8..9 V. It is designed to protect against breakdown of the VT3 gate insulation by high voltage. A gate-source voltage that is dangerous for VT3 may appear when the power is turned on or due to touching the terminals of this transistor.

Details. The KD243A diode can be replaced by any of the KD212, KD243 series. KD243, KD257, 1N4001..1N4007. Instead of KT3102G transistors, any similar ones with small reverse current collector, for example, any of the KT3102, KT6111, SS9014, BC547, 2SC1845 series. Instead of the KT3107G transistor, any of the KT3107, KT6112, SS9015, VS556, 2SA992 series will do. A powerful p-channel field-effect transistor of the IRLZ44 type in a TO-220 package, has a low gate-source opening threshold voltage, a maximum operating voltage of 60 V. The maximum constant current is up to 50 A, the open channel resistance is 0.028 Ohm. In this design, it can be replaced with IRLZ44S, IRFL405, IRLL2705, IRLR120N, IRL530NC, IRL530N. The field-effect transistor is installed on a heat sink with a cooling surface area sufficient for a particular application. During installation, the terminals of the field-effect transistor are short-circuited with a jumper wire.

The autonomous charger can be mounted on a small printed circuit board. As an autonomous power source, you can use, for example, four pieces of series-connected alkaline galvanic cells with a capacity of 4 A/H (RL14, RL20). This option is preferable if you plan to use this design relatively rarely.

If you plan to use this device relatively often or your player consumes significantly more current even when the display is turned off, then it would be advisable to use a 6 V rechargeable battery, for example, a sealed motorcycle battery or from a large hand torch. You can also use a battery of 5 or 6 nickel-cadmium batteries connected in series. When hiking, fishing, to recharge batteries and power a handheld device, it may be convenient to use a solar battery capable of delivering a current of at least 0.2 A with an output voltage of 6 V. When powering the player from this stabilized energy source, it should be taken into account that the regulating transistor is turned on into the negative circuit, therefore, simultaneous power supply of the player and, for example, a small active speaker system is only possible if both devices are connected to the output of the stabilizer.

The purpose of this circuit is to prevent a critical discharge of the lithium battery. The indicator turns on the red LED when the battery voltage drops to a threshold value. The LED turn-on voltage is set to 3.2V.

The zener diode must have a stabilization voltage lower than the desired LED turn-on voltage. The chip used was 74HC04. Setting up the display unit involves selecting the threshold for turning on the LED using R2. The 74NC04 chip makes the LED light up when the discharge reaches the threshold that will be set by the trimmer. The current consumption of the device is 2 mA, and the LED itself will light up only at the moment of discharge, which is convenient. I found these 74NC04 on old motherboards, so I used them.

Printed circuit board:

To simplify the design, this discharge indicator may not be installed, because the SMD chip may not be found. Therefore, the scarf is specially placed on the side and can be cut along the line, and later, if necessary, added separately. In the future I wanted to put an indicator on the TL431 there, as a more profitable option in terms of details. The field-effect transistor is available with a reserve for different loads and without a radiator, although I think it is possible to install weaker analogues, but with a radiator.

SMD resistors are installed for SAMSUNG devices (smartphones, tablets, etc., they have their own charging algorithm, and I do everything with a reserve for the future) and they can not be installed at all. Do not install domestic KT3102 and KT3107 and their analogues; the voltage on these transistors was floating due to h21. Take BC547-BC557, that's it. Source of the diagram: Butov A. Radio constructor. 2009. Assembly and adjustment: Igoran .

Discuss the article MOBILE CHARGING FOR YOUR PHONE

I have been using communicators for a long time, a very convenient all-in-one thing - a notebook, calculator, flashlight, video and photo camera, Internet, video and MP3 player, navigator, safe (for information), radio, game console, and a lot more. Super gadget - what more could you dream of? And I’ll tell you what, about a small nuclear reactor instead of a battery! But at the moment we break off and are happy with the li-ion battery, which, under good load of the device, lasts for 3 hours. There is a way out: we turn down the brightness of the phone to minimum, turn off the Internet, delete live wallpapers, switch to airplane mode and turn it on only to make a call, and then the phone (as stated by the manufacturer) lasts for two days. In general, this is not an option, and I became seriously interested in alternative power sources, we will talk about an additional battery for your gadget or a “Vampire”

Let's probably start with the most basic thing - batteries, I supplied two cans of li-ion bought in radio goods in Vladivostok when I was there on vacation, you can buy in principle any and in any quantities (within reasonable limits) suitable in size, the most important thing is more greed oh, containers. We increase the capacity by paralleling the jars. You can only parallelize identical batteries, ALWAYS balancing them with each other - we connect the minuses (as a rule, they are the body of the can, and we connect the pluses with a resistor with a resistance of 30 ohms.
Using a voltmeter we measure the voltage at the terminals of the resistor. We wait, sometimes for a day, sometimes the same values ​​happen at once. As soon as it becomes less than a hundred millivolts, they can be connected directly, without a resistor. We solder them together and solder the ends to the controller (can be obtained from any old cell phone battery). So we have a high-capacity battery.
WHEN WORKING WITH NAKED CANS WITHOUT A CONTROLLER, BE CAREFUL, DO NOT CONFUSE THE POLARITY AND DO NOT CREATE A SHORT CIRCUIT IN ANY CASE!

We put it aside and scratch our heads with how to charge it, now, of course, charging from a cell phone. They are everywhere and always, and most of them have a USB outlet.

You can directly solder the wires to the battery and USB male and plug them into the charger; they usually go 5V 1A. But it was so boring and uninteresting that I decided to make a charge indicator. We turned on the red LED to charge, the battery was charging, the green light came on, disconnected from charging, both went out.

Transistors marked t06 - pnp PMBS3906, 100mA 40V, complementary to PMBS3904. Unsoldered from an old motherboard.

Resistors R1 and R2 marked 471 - 470 Ohm I got them from old controllers for a cellular battery

Resistor R3 can be set with a value of 1.5 Ohm, but I didn’t find this, I put two in parallel, 1 Ohm each, and it turned out to be 0.5 Ohm. I installed two because I was afraid that they would get very hot at a charge current of about 0.5A I found the 1R00 marking on the diagram hard drive from the laptop.

Diode marked SS14 Description: Diode, Schottky, 1 A, 40 V I had it lying around, I didn’t know where it came from, but if you have hardware with SMD parts, you’ll find something similar on it without any problems.

I bought the most common SMD 3V red and green LEDs, but you can solder them in abundance from circuit boards from cell phones.

I assembled a circuit from what was more or less similar to resistors R1 and R2, which can be set to 330 Ohms

I would like to convey a huge thank you to the Electronics Forum cxem.net. The topic of indicator development, by joint efforts and especially by the Kival participant. Maybe someone will find it useful for general development.

The parts were installed on a piece of copper PCB cut from the board.

Next we mount this little wonderful device on a USB “father” I pulled out of an old data cable

We plug it into the charger and check the functionality

Without load, both LEDs light up; under load, the green one goes out.
In short, the principle is very simple - when the battery is charging, current flows through the circuit and does not allow the green LED to light up, as soon as the controller indicates that the battery is charged and no longer fits into it, the circuit opens, the current stops flowing and the green LED lights up as soon as you remove the diode from charging D3 does not allow current from the battery to flow to the indicator and both go out.

Well, it looks like we’ve decided on the indicator and charging, now we need to figure out how we’ll feed the phone from the battery, because our output is from 3.7v to 4.2v, and for charging a cell phone it’s gently at least 5V and for Nokia even more. Here we need a DC-DC boost converter. Here I give up, I won’t draw diagrams and rant about this because the Internet is teeming with this material, and I don’t have a radio parts store in my city and so I didn’t bother with soldering this element, but stupidly (or cleverly) ordered from the Internet . You can also buy a Chinese charger from one battery and pick it out from there, but I personally doubt its reliability, and we’ll be charging, not halam balam, but expensive communicators.

It would seem that everything is there and all that remains is to connect everything with wires, but some inconveniences arose during the operation of the device, so my device lies like a piece of plastic and it is not clear whether there is a charge in it or is it empty? And lithium-ion batteries really don’t like to sit discharged. I wanted a voltmeter, a small compact voltmeter, since the device was assembled and there was no room for it initially. The search for diagrams, recipes and ready-made units began. And as luck would have it, I walk into a mobile accessories store and see a miracle of Chinese engineering.


Yes, yes, a frog with an LCD screen worth 150 rubles.
I quickly picked it apart :) As it turned out, the voltmeter circuit is made separately from the pulse transformer and is very easily soldered off. The most important thing is to remember how the screen was soldered and where to solder the power wires (by the way, as it turned out, the polarity does not matter) Since my memory has long been weakened by digital technologies, I decided (in order not to forget, I need to take a photo)


After all the manipulations, we get a voltmeter with 4 divisions. With these characteristics, 4 bars 4.14V/ 3 bars 4.04v/ 2 bars 3.94V/ 1 bar 3.84V/ then an empty battery remains until the battery controller cuts off the power, which is about 3 .4 - 3.6V
Since the voltmeter also consumes a certain amount of electricity that is dear to us, we connect it through a button. Clicked, looked, let go!

Next we are looking for a suitable box where we can put everything we have acquired through back-breaking labor, welded together with sweat and blood. In an unequal battle, I took the box of shadows from my wife (the shadows and mirror were returned) and put everything there.

Solder according to the diagram

I placed the USB connectors on a strip of tin to increase the area when gluing. We glue the battery with double-sided tape, the button with super glue, the USB connectors are soldered (as mentioned above) they are soldered to the tin, which in turn is glued with super glue, we cut out a rectangular hole under the LCD screen, we carry out installation and fitting carefully - the glass is very fragile. We sit on hot glue.

Well, that's all! We decorate it to your taste and use the device!

This tutorial will show you how you can get 5V USB from a 9V battery and use it to charge your mobile phone.
The photo shows the assembled circuit in action, but this is not the final version, since I will also make a housing for it at the end.
So let's start making it.

Materials

• Old battery for the case.
• USB port.
• Regulator chip 7805.
• One green LED.
• Resistors 220R - 3 pcs.
• Solder.
• Wires.

Scheme

Assembling the charger according to the diagram