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How to make a portable phone charger with your own hands. Mobile phone charger. Charger activation and identification unit

My favorite mobile phone NOKIA 6500, which was bought about six months ago, was not initially charged. 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 it was inconvenient to constantly remove the battery.

It was in connection with this that I decided to install a wireless charging system on my phone. The system was assembled according to my own idea within a couple of hours.

How wireless charging works

The principle of operation of such a wireless charging circuit 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 Diagram

Electricity is transferred from one circuit to another by induction, the current that has arisen in the second circuit is first rectified and fed 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. The usual blocking oscillator circuit on a single 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, carefully wind 20 turns, then twist the wire, make a tap 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 and bipolar ones, with field 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 literally set any. Of the bipolar ones, domestic ones can be used: 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 - shook 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 contour on a small piece of plastic, the turns need to be gradually strengthened with superglue, the work is quite dirty and long. After winding, we separate the circuit from the plastic stand on which it was wound. It is convenient to do this 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 completed with the phone, now you need to put 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.

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

We examined the scheme of a simple autonomous charger for mobile equipment, operating on the principle of a simple stabilizer with a decrease in battery voltage. This time we will try to assemble a slightly more complex, but more convenient memory. 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 a few tens of hours with the display turned off, or to play several hours of video or several hours of reading e-books. If the mains socket is unavailable or due to bad weather or other reasons, the power supply is turned off for a long time, then various mobile devices with color displays will have to be powered from built-in power sources.

Given that these devices consume a lot of current, their batteries may be depleted before the moment when electricity from the wall outlet becomes available. If you do not want to immerse yourself in primeval silence and peace of mind, then to power pocket devices, you can provide a backup autonomous power source that will help out both during a long trip into the wild, and in case of man-made or natural disasters, when your locality may be on several days or weeks without power.


Scheme of a mobile charger without a 220V network

The device is a linear compensation type voltage stabilizer with low saturation voltage and very low own current consumption. The energy source for this stabilizer can be a simple battery, rechargeable battery, solar or manual power 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.

Resettable fuse protects the stabilizer and battery from overload. Reverse 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 keep the output voltage stable, a control unit assembled on VT1, VT4 is used.

An ultra-bright blue LED is used as a reference voltage source, which, simultaneously with the function of a micropower zener diode, is an indicator of the presence of an 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, VT1 also opens more. which shunts the gate-source of a powerful field-effect transistor VT3.

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

Details. Diode KD243A can be replaced by any of the series KD212, KD243. KD243, KD257, 1N4001..1N4007. Instead of KT3102G transistors, any similar collectors with a low reverse current are suitable, for example, any of the KT3102, KT6111, SS9014, VS547, 2SC1845 series. Instead of the KT3107G transistor, any of the KT3107, KT6112, SS9015, BC556, 2SA992 series will do. A powerful p-channel field-effect transistor of the IRLZ44 type in the TO-220 package has a low gate-source opening threshold voltage, the maximum operating voltage is 60 V. The maximum direct current is up to 50 A, the open channel resistance is 0.028 Ohm. In this design, it can be replaced by IRLZ44S, IRFL405, IRLL2705, IRLR120N, IRL530NC, IRL530N. The field-effect transistor is mounted on a heat sink with sufficient cooling surface area for a particular application. During installation, the terminals of the field-effect transistor are short-circuited with a wire jumper.


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


If you plan to use this device relatively frequently, or if your player draws significantly more current even when the display is off, then a 6V rechargeable battery, such as a sealed motorcycle battery or a large flashlight, may be worthwhile. You can also use a battery of 5 or 6 pieces of 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 at an output voltage of 6 V. When powering the player from this stabilized power source, please note that the regulating transistor is turned on into the "minus" circuit, therefore, simultaneous power supply of the player and, for example, a small active speaker system is possible only if both devices are connected to the output of the stabilizer.

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


The zener diode must have a stabilization voltage below the desired turn-on voltage of the LED. Chip used 74HC04. Setting the display unit consists in selecting the threshold for turning on the LED using R2. The 74NC04 chip makes it so that the LED lights up when discharged to a threshold, which 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 74NC04s on old motherboards, that's why I used them.

Printed circuit board:

To simplify the design, this discharge indicator can not be set, because the SMD chip can not be found. Therefore, the scarf is specially on the side and it can be cut off 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 stands with a margin for different loads and without a radiator, although I think you can put weaker analogues, but already with a radiator.

SMD resistors are installed for SAMSUNG devices (smartphones, tablets, etc., they have their own charge algorithm, and I do everything with a margin for the future) and you can not install them at all. Do not install domestic KT3102 and KT3107 and their analogues, I had voltage floating on these transistors due to h21. Take BC547-BC557, that's it. Scheme source: Butov A. Radio designer. 2009. Assembly and adjustment: Igoran .

Discuss the article MOBILE CHARGER FOR PHONE

Creating a do-it-yourself 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 they are easy to get. USB solar chargers are ideal for charging small devices such as phones.


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


For example, the iPhone 4's 2000 mAh battery can still be fully recharged with a homemade solar charger with two or four AA batteries, but the iPad 2 has 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. First, compared to this homemade charger will cost you very cheap. Secondly, it is very easy to assemble it. And most importantly, this lithium USB charger is safe to use.

Step 1: Necessary components to assemble a USB solar charger.


Electronic components:

  • Solar panel 5V or higher
  • 3.7 V lithium-ion battery
  • Li-Ion Battery Charge Controller
  • DC boost USB circuit
  • 2.5 mm socket with panel mount
  • 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 case)

Instruments:

  • soldering iron
  • hot glue gun
  • Drill
  • Dremel (optional but preferred)
  • wire cutters
  • Wire stripper
  • Help a friend

This tutorial will show you how to make a solar powered phone charger. You can refuse to use solar panels and limit yourself to making ordinary USB chargers on lithium-ion batteries.


Most of the components for this project can be purchased from online electronics stores, but the USB DC boost circuit and Li-Ion battery charge controller will not be easy to find. Later in this guide, I will tell you where you can get most of the necessary components and what each of them is needed for. Based on this, you yourself decide which option suits you best.


Step 2: Benefits of lithium battery chargers.


Maybe you don’t know, but most likely the lithium-ion battery is right now in your pocket or on the table, or maybe in your wallet or. Most modern electronic devices use lithium-ion batteries, which are characterized by high capacity and voltage. They can be recharged multiple times. Most AA batteries are nickel-metal hydride batteries in terms of chemical composition and cannot boast of high technical characteristics.

From a chemical point of view, the difference between a standard AA NiMH battery and a lithium-ion battery is the chemical elements contained within the battery. If you look at Mendeleev's 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 has only one valence electron.


And just for this reason, there are a lot of complaints about lithium - sometimes it can get out of control due to its high chemical activity. A few years ago, Sony, a leader in laptop batteries, manufactured a batch of low-quality laptop batteries, some of which spontaneously ignited.

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

This is why extreme care must be taken when working with lithium batteries. If handled with care, they are quite safe. But if you do unacceptable things with them, then this can lead to big trouble. Therefore, they should only be used 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's better to just buy a ready-made circuit that you can be sure of. Several charge control schemes are available to choose from.

Adafruit is currently releasing the second generation of lithium battery charge controllers with multiple input voltages available. These are quite good controllers, but they are too large. It is unlikely that on their basis it will be possible to assemble a compact charger.

On the Internet, you can buy small modules of lithium battery charging controllers, which are used in this manual. Based on these controllers, I also collected many others. I like them for their compactness, simplicity and the presence of LED indication of battery charge. As with Adafruit, when the sun is out, the lithium battery can be charged via the controller's USB port. The ability to charge via USB port is an extremely useful option for any solar charger.

Regardless of which controller you choose, you must know how it works and how to use it correctly.

Step 4: USB port.


The USB port can charge most modern devices. This is the standard all over the world. Why not just connect the USB port directly to the battery? Why do I need a special circuit for USB charging?

The problem is that the USB standard is 5V, and the Li-Ion batteries we'll be using in this project are only 3.7V. enough to charge various devices. Most commercial and homemade USB chargers, on the other hand, use step-down circuits, as they are built 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 circuit used in this manual was chosen as a result of extensive testing of various options. It is almost identical to Adafruit's Minityboost circuit but costs less.

Of course you can buy an inexpensive USB charger online and disassemble it, but we need a circuit that converts 3V (voltage from two AA batteries) to 5V (voltage from USB). Dismantling a conventional or car USB charger will not work, since their circuits work to lower 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 chargers. Apple devices check the data pins on the USB to know where they are connected. If the Apple gadget determines that the information pins are not working, then it will refuse to charge. Most other gadgets do not have such a check. Trust me - I have tried many cheap eBay charging schemes - none of them have been able to charge my iPhone. You don't want to be unable to charge Apple gadgets from your homemade USB charger.

Step 5: Choose a battery.

If you google a little, you will find a huge variety of sizes, capacities, voltages and costs. 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 mobile phone battery. Indeed, we need a battery exclusively for 3.7 V, since the charging circuit is designed specifically for this voltage.

The fact that the battery should be equipped with built-in protection against overcharging and overdischarging is not even discussed. This protection is usually referred to as "PCB protection". Search for these keywords on the eBay online auction site. From itself, it is just a small printed circuit board with a chip that protects the battery from excessive charge and discharge.

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 about 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're not going to make a solar-powered charger, you can skip this step.

This guide uses a 5.5V 320mA hard plastic solar panel. Any large solar panel will do. 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. The wire with the white stripe is negative and the all black wire is positive.


Solder the wires to the appropriate pins on the back of the solar panel.

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

Step 7: Drilling the tin box or case.


Since I used an Altoids tin box as the case, I had to work a little with a drill. In addition to a drill, we 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 location of the components with a marker.


After designating the places, you can get to work.

You can remove the USB port in several ways: 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 marked area with a drill.


Sand the hole with a dremel. Be sure to follow safety precautions so as not to injure your fingers. In no case do not hold the box in your hands - clamp it in a vise.

Drill a 2.5mm hole for the USB port. If necessary, expand it with a dremel. If you don't plan on installing a solar panel, then the 2.5mm hole is not necessary!

Step 8: Connecting the charge controller.


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


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


Fix the 1N4001 diode, charge controller and 2.5mm connector. Position the connector in front of you. If you look at it from left to right, then the left contact will be negative, the middle contact will be positive, and the right contact will not be 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 shrink tubing.

Solder another wire to the leg of the diode, next to which the mark is applied. Solder it as close to the base of the diode as possible to save more space. Solder the other side of the diode (no label) 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 terminal on the board. In addition, it is advisable to use heat shrink tubing.

Step 9: Connecting the battery and USB circuits.


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.


Cut some wires first. Solder them to the positive and negative pins on the USB circuit, which are located on the underside 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. I remind you that the red wires are positive, and the black wires are negative.


After you have twisted the wires together, weld them to the contacts on the battery, which are located on the back of the charge controller board. Before soldering the wiring, it is advisable to thread through the holes.

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


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

Step 10: Electrical isolation of all components.


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

Glue a few strips of tape on the bottom and sides of the tin box. It is in these places that the USB circuit and the charging controller will be located. The photographs show that the charge controller was left loose with me.

Try to carefully insulate everything so that a short circuit does not occur. Before applying hot glue or winding electrical tape, make sure the soldering is strong.

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 if the switch that is needed to enable and disable the "charge mode" is working.


And finally, you need to fix 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: Operation of the Homemade Solar Charger.


In conclusion, let's talk about the proper operation of homemade USB charging.

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


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 work, but this is not the final version, since I will also make a case for it at the end.
So, let's start making.

materials


The picture shows the components needed to assemble the charger, including one empty case from an old battery, in which the device will be built.
Accessories and materials:
  • Old battery for the case.
  • USB port.
  • Microcircuit regulator 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 circuit itself of a simple converter.

Assembling the charger according to the scheme


After disassembling the old battery, parts can be soldered to the base with a connector. Everything is assembled in five minutes, and I think that nothing needs to be explained, 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 need to be configured and starts working immediately.
The LED indicates the presence of charging current. If it is not lit, then the battery is completely discharged, or the phone is fully charged.