USB homemade portable charger for a smartphone. Mobile phone charger. Advantages and disadvantages of wireless chargers

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

The photo shows the components necessary to assemble the charger, including one empty case from an old battery, in which the device will be built.
Components and materials:

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

Scheme

The diagram shows the pinout of the 7805 regulator, the USB connector and the actual circuit of the simple converter.

Assembling the charger according to the diagram

After disassembling the old battery, parts can be soldered to the base with the connector. Everything is assembled in five minutes, and I think that nothing needs explanation, except for the resistors connected to the middle USB contacts - Data+ and Data-. And they are needed so that the cell phone itself understands that it is connected to a charger, and not to a computer for data transfer.
The circuit does not require any settings and starts working immediately.
The LED indicates the presence of charging current flowing. If it is not lit, it means the battery is completely discharged or the phone is fully charged.

One of the most important problems of a modern person who has a smartphone is the constant drain on the device’s battery. Portable chargers have been created especially for such cases, which allow you to connect your gadget using a USB cable and charge your smartphone using the battery built into the charger.

So, to make a portable charger we need:
- Two crown batteries (one of the batteries can be used),
- Box (you can use a metal candy box),
- A switch that can be removed from an old cassette player or a broken children's toy
- And most importantly, a USB charger for the car, which can be purchased for about 2-3 dollars,
- And also the copper wires with which we will connect everything.

First of all, we must make a removable brand for the battery. If you have old toys or devices at home that use Krona batteries, then ready-made stamps can be removed from them. If there are no such toys or devices, then you can make a brand yourself. To do this, you need to remove the top part of the crown battery, spread flux on the metal contacts on the inside and solder the copper wires to them. For fixation and insulation, you can use regular hot melt adhesive.

The stamps are ready, they can be attached to the contacts of the second battery (wide contact to narrow, and narrow to wide).

The next thing we need to do is disassemble the car charger by taking the board on which the USB connector is located. All that remains is to assemble all the components of our portable charger and connect everything through the switch.

When connecting the mark to the battery, you can see which wire is positive and which is negative if you use different colored wires. If not, then you can mark it as a plus for greater convenience and ease.

The central wire or spring on a car charger is always positive, and the wire located on the side is always negative. So, we must connect the positive wire of our battery to the switch, and the negative wire directly to the charger board.

If the positive wire on the charger is made in the form of a spring, it can be replaced with a regular one for greater convenience.

After this, two positive wires need to be soldered to two contacts on the fork.

The device is almost ready. All that remains is to assemble it in a box, on which in the side you need to cut two passages for a USB input and a switch.

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 a very simple and fairly fast solution. 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 discovering some 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. A huge contribution was made by the 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 a mobile phone with a receiver comes into 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 have already conducted similar experiments before us, posting detailed instructions and diagrams for assembling wireless charging with their 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 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. The latter option is perfect for users whose charging port has died.
4. That's it, close the 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 first practice with the simplest option presented in the instructions, so that they 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

do you need it?

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.

Photo: Koolpad Qi

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.

We will tell you how to make a wireless charger for your phone with your own hands or buy a ready-made one.

The transmitting circuit has two half-windings, which are connected to the middle point.
The middle point goes through the inductor to the power supply plus. Limiting resistors that go to the bases of the transistors are also connected to the power supply plus. The diode goes from the base of one transistor to the collector of the opposite transistor. The same with the second diode.

The collector goes to the ends of the winding. For DIY construction there is an option without a midpoint. To do this, you need to take two chokes, parallel one of the terminals of each inductor and connect it to the power supply positive. Disconnect the free leads to the collectors of each transistor. You can assemble this option with your own hands, but the elements will get very hot.

Power depends on the elements used. A device made according to this scheme can be made both weaker and stronger. Using this scheme, you can construct a 2-amp wireless charger with your own hands.

Making your own reel

First, let's wind the outline with our own hands. It doesn't have to be very neat. You can use a piece of plastic with a diameter of 5-10 cm or your fingers.

We take one long wire. Fold it in half. Straighten it.

We wrap 5 turns on fingers or plastic.

Now we secure the coils themselves around the entire circumference with glue or tape.

We are left with three tips. One with a fold. Cut off this fold. Now we have 4 tips. We clean them.

We will need to connect either the end of the first winding to the beginning of the second, or the beginning of the first winding to the end of the second. To check what is connected to what, we use a multimeter.

Set the multimeter to diode test mode. We connect the multimeter to each tip at both ends simultaneously. We see that when connected to some ends the multimeter reacts, but when connected to others it does not. These tips should be on different sides. We must twist them together and solder them. This is the middle point. The remaining tips are two collector windings that go to the transistors. Now we are ready to assemble the charger ourselves.

Putting it all together with our own hands

To assemble the device with your own hands, we take solder, a soldering iron and a circuit board. First we solder two transistors.

After this we solder the diodes.

These are resistors. One tip goes to the diodes, the other to the board.

Now we solder the circuit with our own hands. We wound it up earlier. Now you need to tin its two windings and connect them to the circuit.

Receiver

As a rule, people don’t dare to make a wireless charging receiver with their own hands, since here you already need to get into the phone. A rather crude separate receiver can be made with your own hands just to check if the transmitter works. In a DIY receiver, it is advisable to use a UF diode as well.

Capacitor with a capacity of 47-100 µF. Operating voltage - 25 volts. The second capacitor can be used for 10-16 Volts. Capacity - 47 µF. The circuit of the receiver, made by hand, is also 10 turns. Wire diameter - 0.75 mm.

It is more difficult to understand the written instructions than to follow the actions shown. We have attached a video on how to make a wireless phone charger with your own hands.

Review of ready-made devices for those who do not want to assemble them with their own hands

Making your own phone charger isn't all that difficult, but few people want to mess with it. It’s much easier to buy it than to design it yourself if you have the opportunity and don’t have a particular desire to make something. For that category of users who did not want to build everything with their own hands, we offer an overview of popular wireless chargers.

RAVPower Wireless Charging Pad
The battery of this device has a capacity of 5000 mAh, thanks to which it can simultaneously charge two smartphones. But they must support the Qi standard.

Anker Wireless Charger PowerPort Qi Wireless Charging Pad
It has a temperature sensor to monitor overheating, overcharge protection. When this charger is not in use, it enters sleep mode. Costs about $17.

Woodpuck FAST Edition Bamboo Qi Wireless Charging Pad
This charger is more powerful and more stylish. It is made of bamboo, which in itself is a big advantage. At the same time, it charges the phone 40% faster. Price about $40.

Samsung Fast Charge Qi Wireless Charging Pad
This option has support for fast charging, but it costs about $50. Naturally, this is the best option for the same smartphones and tablets from Samsung, if you want to spend no more than an hour on charging.

Tylt Vü
What makes this wireless phone charger different from the rest is its unusual shape, which causes the phone to charge in an unusual position. It looks like a regular stand. The phone or tablet is placed on it in a semi-tilt, so it becomes much more convenient to use them while charging.

Nokia DT-903
The Nokia phone charger has a backlight that changes color to match the case. Especially for the native Nokia Lumia, a missed call and SMS indicator is built-in.

Advantages

The previous advantage is used to equip public places with phone chargers. That is, soon you won’t have to carry a charger with you everywhere and look for a cafe with sockets (the tables next to which, as a rule, are always occupied; and for a long time). But now you have to look for a cafe with wireless chargers. Which will probably be busy too. That is life…

If your smartphone is not very new, some elements in the socket may be worn out. Because of this, problems can also arise: the contacts simply will not touch each other tightly.

Flaws

The minimum cost of such charging is about 700 rubles. Quite inexpensive, you say. But keep in mind that the speed is much lower than that of the standard model. You have to pay extra for high speed. As a result, one wireless phone charger will cost at least 2.5 thousand.

In addition to the fact that energy efficiency is less, part of it will simply go away in the form of heat.

However, this method is not suitable for all phones. The same iPhones, for example, need additional devices.

FAQ

Above we told you how to do the exercises yourself and which one is better to buy. Now it remains to clarify some points. This technology is quite new, so not everyone knows what it is and how to use wireless charging. Here we answer the most popular questions.

What is the name of wireless phone charging?

Wireless charging is, of course, a name “for the masses.” Few people know what wireless phone charging is called. And its name is this: Qi standard induction coil. The name reflects the principle of its operation. Phone chargers of this type contain an inductive current transmitter, which charges the phone. And the little word Qi also has its own history, a very ancient one - it is the energy of Qi, so it is written in Latin. The concept is taken from traditional Chinese medicine.

How does wireless charging work?

The basic operating principle of wireless phone charging is magnetic induction. Electric current creates a magnetic field in the charger, which transfers voltage to the battery in the phone or tablet. The Wireless Electronic Energy Consortium has developed its own Qi standard specifically for such devices, which can be used to evaluate devices regardless of the manufacturer. The standard determines the current power supplied to the coil - 5 Watts.

How does wireless charging work? The magnetic field operates at a distance of 4 cm. It begins to form when a signal is given - a compatible device has appeared in the coverage area. Most often, this signal is given by the smartphone itself. The NFC function helps them with this. It stands for Near Field Communication. Under the influence of the voltage of this field, a current also appears in the coil built into the phone, which is supplied to the battery.

Which phones support wireless charging?

In the previous paragraph, we described the principle of wireless phone charging. After reading it, we understand that according to the Qi standard, wireless charging will work if a receiver-receiver is built into the smartphone. This receiver will be able to receive energy from the magnetic field that is created in the charger coil. Which phones support wireless charging? Almost all modern smartphones and tablets are created taking into account this technology. These are companies such as Yota, Sony, Nokia, Samsung, Kyosera, Motorola, LG, Asus, Google, HTC and Blackerry.

How do you know if your phone supports wireless charging or not?

How do you know if your phone supports wireless charging? This depends on the specific model. For example, Samsung Galaxy Note Edge supports it, but Sasung Galaxy Note 3 does not. You can ask your sales consultant or look on the Consortium website. There is a form on this page. By entering the brand name in the Brand name line and the phone name in the Product name line, you will find out whether your device is on the list or not. If not, don't worry. For those models that are not equipped with the necessary technology, special adapters are produced. And it would be a good idea to buy them, because wireless chargers are gradually appearing in public places like coffee shops or airports. They are even going to build them into IKEA furniture.

How to charge wirelessly

How to charge wireless charger? Paradoxically, this must be done using a wire. If voltage is supplied to the phone through the air, then current flows into the charger itself in the standard way. First, assemble the power adapter and connect it to the device. Then we connect the adapter to the outlet. Some models have micro-USB cables, which allows you to charge them from laptops, for example.

How to connect and charge your phone with wireless charging

How to connect and charge your phone with wireless charging? As easy as pie. After connecting the device to an energy source, you need to place it on a flat surface and place the phone on top. It must be positioned so that the battery is within the coverage area, that is, in the middle of the backrest.

My favorite mobile phone NOKIA 6500, which was purchased about six months ago, initially did not charge. Repair work was carried out, after which the phone worked for about a month. The main problem was that the phone had to be charged using a universal charger, and constantly removing the battery was inconvenient.

It is in this regard that I decided to install a wireless charging system on my phone. The system was assembled according to our own ideas within a couple of hours.

How wireless charging works

The operating principle of this wireless charging scheme is quite simple. The role of the charger is played by the transmitting circuit; the device itself consists of two circuits - a transmitter and a receiver.

The receiving circuit (flat coil) is located in the phone itself, the transmitter is made in the form of a small stand, inside of which the transmitting coil is hidden.

Wireless charging circuit

Electricity is transferred from one circuit to another by induction; the current generated in the second circuit is first rectified and supplied to the battery. Literally any low-power Schottky diode can be used as a rectifier.

Let's start assembling wireless charging with our own hands from the transmitter.

Transmitter

The transmitter circuit is simple and clear. A typical blocking oscillator circuit using one transistor. The frame for winding the transmitting coil is at your discretion. It is advisable to take a frame with a diameter of 7-10 cm. We wind 40 turns of copper wire with a diameter of 0.5 mm onto the frame. The winding has a tap from the middle. First, we carefully wind 20 turns, then we twist the wire, make a branch, and wind the remaining 20 turns in the same direction. Is everything clear with the coil? Let's move on.

Absolutely any transistor, I tried both field-effect and bipolar ones, with field-effect ones it charges a little faster. You can use field keys of the IRFZ44/48, IRL3705, IRF3205 series (I indicate only those that I used myself), but you can use literally any. Of the bipolar ones, you can use domestic ones: KT819, 805, 817, 815, 829. The choice is not critical. You can also use direct conduction transistors, but in this case you will have to change the polarity of the power supply.

The value of the base resistor is not critical (22 Ohm-830 Ohm).

Receiver

The receiving circuit was running for half an hour. The coil is flat, consists of 25 turns of wire 0.3-0.4 mm. It is convenient to wind the circuit on a small piece of plastic; the coils need to be gradually strengthened with superglue; the work is quite dirty and time-consuming. After winding, we separate the circuit from the plastic stand on which it was wound. This is convenient to do with a mounting knife or blade.

In my case, the charging connector on the phone did not work, so I connected the charger directly to the battery. This solution is inconvenient because the sensor will not show that the phone is charging. Everything is done with the phone, now you need to install the back cover.

Charging time directly depends on the power of the power source, in my case, the factory charger of the experimental phone was used. The device provides an output voltage of 5V at a current of 350mA.

This wireless phone charger works flawlessly; with this arrangement of components, the mobile phone is fully charged in 7 hours, it takes a long time, but it charges. You can speed up the charging time only by making the circuit stronger - use a more powerful power supply and wind the circuit with a thicker wire.