Alteration of charging from a mobile current increase. Modernization of chargers

We are interested in the second type of chargers, because most vehicles are operated with short runs, i.e. they started the car, drove a certain distance, and then drowned it out. Such operation leads to the fact that the battery of the car runs out of charge rather quickly, which is especially typical for winter time. Therefore, such stationary units are in demand, with the help of which you can very quickly charge the battery, returning it to working condition. The charging itself is carried out using a current of about 5 Amperes, and the voltage at the terminals ranges from 14 to 14.3 V. The charging power, which is calculated by multiplying the voltage and current values, can be provided from the computer's power supply, because its average power is about 300 -350 watts.

Converting a computer PSU into a charger

Now all cell phone manufacturers have agreed and everything that is in stores is charged via a USB connector. This is very good because chargers have become universal. Basically, a cell phone charger is not.

This is only an impulse source direct current voltage of 5V, and the charger itself, that is, the circuit that monitors the battery charge, and provides its charge, is located in the very cell phone... But, the point is not in this, but in the fact that these "chargers" are now sold everywhere and are already so cheap that the issue of repairs somehow disappears by itself.

For example, in the store "charging" costs from 200 rubles, and on the well-known Aliexpress there are offers from 60 rubles (including delivery).

Schematic diagram

Typical scheme chinese charging copied from the board is shown in fig. 1. There may be an option with the rearrangement of the diodes VD1, VD3 and the Zener diode VD4 to the negative circuit - Fig.2.

And more "advanced" options may have rectifier bridges at the input and output. There may be differences in the denominations of parts. By the way, the numbering on the diagrams is arbitrary. But this does not change the essence of the matter.

Rice. 1. Typical diagram of a Chinese wall charger for a cell phone.

Despite its simplicity, this is still a good switching power supply, and even a stabilized one, which is quite suitable for powering something other than a cell phone charger.

Rice. 2. Scheme of a network charger for a cell phone with a changed position of the diode and zener diode.

The circuit is made on the basis of a high-voltage blocking generator, the pulse width of which is regulated by an optocoupler, the LED of which receives voltage from a secondary rectifier. The optocoupler lowers the bias voltage at the base of the VT1 switch transistor, which is set by the resistors R1 and R2.

The primary winding of the transformer T1 serves as the load for the VT1 transistor. The secondary, step-down, is winding 2, from which it is removed output voltage... There is also winding 3, it also serves to create a positive feedback for generation, and as for a negative voltage source, which is made on the diode VD2 and the capacitor C3.

This negative voltage source is needed to reduce the voltage at the base of the VT1 transistor when the optocoupler U1 opens. The stabilization element that determines the output voltage is the VD4 Zener diode.

Its stabilization voltage is such that, together with the direct voltage of the IR LED of the optocoupler U1, it gives exactly the very necessary 5V that is required. As soon as the voltage at C4 exceeds 5V, the VD4 zener diode opens and current flows through it to the optocoupler LED.

And so, the operation of the device raises no questions. But what if I don't need 5V, but, for example, 9V or even 12V? This question arose along with the desire to organize a network power supply for a multimeter. As you know, popular in radio amateur circles, multimeters are powered by "Krona" - a compact 9V battery.

And in "field-field" conditions it is quite convenient, but in home or laboratory conditions I would like to be powered from the mains. According to the scheme, "charging" from a cell phone is, in principle, suitable, it has a transformer, and the secondary circuit is not in contact with the mains. The only problem is the supply voltage - "charging" gives 5V, and the multimeter needs 9V.

In fact, the problem of increasing the output voltage is very simple to solve. You just need to replace the VD4 Zener diode. To get a voltage suitable for powering a multimeter, you need to put a zener diode at a standard voltage of 7.5V or 8.2V. In this case, the output voltage will be, in the first case, about 8.6V, and in the second about 9, ЗV, which, both of which is quite suitable for a multimeter. Zener diode, for example, 1N4737 (that's 7.5V) or 1N4738 (that's 8.2V).

However, another low-power zener diode for this voltage is also possible.

Tests have shown Good work multimeter when powered from such a power source. In addition, an old pocket radio powered by Krona was also tried, - it worked, only the noise from the power supply interfered slightly. The voltage in 9V is not limited at all.

Rice. 3. Voltage regulation unit for reworking the Chinese charger.

Want 12V? - Not a problem! We put a zener diode at 11V, for example, 1N4741. You just need to replace the capacitor C4 with a higher voltage one, at least by 16V. You can get even more stress. If you remove the zener diode at all, there will be a constant voltage of about 20V, but it will not be stabilized.

It is even possible to make a regulated power supply by replacing the zener diode with a regulated zener diode such as the TL431 (Figure 3). The output voltage can be adjusted, in this case, variable resistor R4.

Karavkin V. RK-2017-05.

Over the past several years, a large number of cell phone chargers have accumulated in my house, which are no longer used for their intended purpose due to the connectors that are not suitable for new models of smartphones.

There are five power supplies from Nokia alone. It was decided to take advantage of them - to make a couple of spare chargers.

Some of these units have an output voltage of 5 volts, which is suitable for modern digital technology with low charging currents. But the task of making a super charger was not mine.

Also from unnecessary "gizmos from the past" I found a couple of adapters for a mouse - from ps / 2 to usb, plus a connector for micro usb - that's all the accessories for my homemade product.

Charging assembly

The adapter body can be easily disassembled. After removing all unnecessary, we leave only the plug itself.

Only a pair of extreme contacts will be used. We make a couple of small holes for plastic clamps, which will further tighten the case and fasten the cables.

With the charger, everything is simple: we cut off the old plug. I had a couple of faulty cables available (the cat bit), but with a whole micro-connector, and there were new collapsible connectors.

Having soldered the cables according to the scheme, we fix them with a clamp.

We close the case and also fasten it with a coupler. The adapter body serves as both a junction box and a valid usb.

There was a small economic nuisance, a shortage of chargers. There are four of us in the family. Each or everyone has their own phone. It seems that each phone has its own charger. But the youngest daughter broke down, one was forgotten in the village. Where has gone another one, probably only Pushkin knows - the one who is Alexander Sergeevich.
So much for the deficit. All phones with microUSB connector. But one charger for four phones is not enough.

Accidentally caught my eye charger, from a phone that we no longer have... The tricky connector ruled out any hope of further use. But the characteristics are what you need: 5 volts, 550 milliamps. Change the cord? And if I do it better - I will put the connector.

Using the charger with USB connector has two advantages:
-the cord, which often breaks, becomes easily replaceable;
-you can charge devices with mini and microUSB, you just need to change the cord.

I bought a connector designed for board mounting. Maybe I looked inattentively, but did not find better option... The price is 15 rubles.

I opened the charger case. I myself do not know a humane way to do this, and I will not tell you. With a knife and kind word... Charger cases are not intended for easy disassembly and repair - they are assembled with latches without screws. But they are not glued either.

It took me a while to realize that the board can be easily removed from the case. The pins through which the alternating current is supplied are embedded in the housing. On the inside, they end with plugs, and there are contact pads on the board.

We take out the board. I cut the wire so that there were pieces of red and black. Just to indicate where which is. Now prepare a new piece of black and red wire. At the exit from the housing, the wires often break. It is better to replace this area immediately. Soldered wires, connector. I inserted the board into the case. Without closing the case, I connected the phone and put the connector. The signal light is on, which means charging is in progress.

Now you can do the body... I turned off the device from the network and chose the place where the connector will be. I cut out the necessary window with a knife and a hacksaw blade. I assembled the charger. The connections and the connector itself are insulated. I inserted the connector into the case. I placed the wires neatly. I closed the lid until it clicks. The remaining large gaps were repaired with hot glue, which was from a glue gun. I checked it again - it works.

I have been using this charger for a week now. Now, I am already glad that I did not find a suitable device in the store. With USB, convenient and inexpensive.

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Power supply - from cell phone charger
I. NECHAEV, Kursk

Small-sized wearable equipment (radios, cassette and disc players) are usually powered by two to four galvanic cells. However, they do not last long, and they have to be replaced quite often with new ones, so at home it is advisable to power such equipment from a network unit. Such a source (in common parlance it is called an adapter) is easy to acquire or make yourself, since there are a lot of them described in the amateur radio literature. But you can do it differently. Almost three out of every four residents of our country today have a cell phone (according to the research company AC & M-Consulting, at the end of October 2005 the number of subscribers cellular in the Russian Federation exceeded 115 million). Its charger is used for its intended purpose (to charge the phone's battery) for only a few hours a week, and the rest of the time is idle. How to adapt it to power small-sized equipment is described in the article.

In order not to spend money on galvanic cells, owners of wearable radios, players, etc. equipment use batteries, and in stationary conditions they power these devices from the network alternating current... If there is no ready-made power supply unit with the required output voltage, it is not necessary to buy or assemble such a unit yourself; you can use a cell phone charger for this purpose, which many have today.

However, you cannot directly connect it to a radio or player. The fact is that most of the chargers included in the cell phone kit are an unstable rectifier, the output voltage of which (4.5 ... 7 V at a load current of 0.1 ... apparatus. The problem can be easily solved. To use the charger as a power supply, it is necessary to connect a voltage stabilizer adapter between it and the device.
As the name suggests, a voltage regulator should be the basis of such a device. It is most convenient to assemble it on a specialized microcircuit. The wide range and availability of integral stabilizers allow us to manufacture a wide variety of adapters.
The schematic diagram of the voltage regulator adapter is shown in Fig. 1. Chip DA1 is chosen

depending on the required output voltage and the current consumed by the load. The capacity of capacitors C1 and C2 can be in the range of 0.1 ... 10 μF (rated voltage - 10 V).
If the load consumes up to 400 mA and such a current can be supplied by the charger, as DA1, you can use the KR142EN5A microcircuits (output voltage - 5 V), KR1158ENZV, KR1158ENZG (3.3 V), KR1158EN5V, KR1158EN5G (5 V), as well as five-volt imported 7805, 78M05. Chips of the LD1117xxx, REG 1117-xx series are also suitable. Their output current is up to 800 mA, the output voltage is from the range of 2.85; 3.3 and 5 V (for LD1117xxx - also 1.2; 1.8 and 2.5 V). The seventh element (letter) in the designation LD1117xxx indicates the type of case (S - SOT-223, D - S0-8, V - TO-220), and the following two-digit number indicates the nominal value of the output voltage in tenths of a volt (12 - 1.2 V, 18 - 1.8 V, etc.). A hyphenated number in the designation of the REG1117-xx microcircuits also indicates the stabilization voltage. The pinout of these microcircuits in the SOT-223 package is shown in Fig. 2, a.

It is also permissible to use stabilizer microcircuits with an adjustable output voltage, for example, KR142EN12A, LM317T. In this case, you can get any value of the output voltage from 1.2 to 5 ... 6 V.
When powering equipment that consumes a small current (30.100 mA), for example, small-sized VHF FM radio receivers, the adapter can use the microcircuits KR1157EN5A, KR1157EN5B, KR1157EN501A, KR1157EN501B, KR1157EN502A, KR1157115811502B ), KR1158ENZA, KR1158ENZB (3.3 V). Drawing possible option printed circuit board adapter with used
the use of microcircuits of the latest series is shown in Fig. 3. Capacitors C1 and C2 - small-sized oxide of any type with a capacity of 10 μF.

You can significantly reduce the size of the adapter by using miniature microcircuits of the LM3480-xx series (the last two digits indicate the output voltage). They are available in the SOT-23 package (see fig. 2.6). A drawing of the printed circuit board for this case is shown in Fig. 4. Capacitors C1 and C2 - small-sized ceramic K10-17 or similar imported ones with a capacity of at least 0.1 μF. Appearance adapters mounted on boards manufactured in accordance with Fig. 3 and 4 is shown in Fig. 5.

It should be noted that the foil on the board can act as a heat sink. Therefore, the area of ​​the conductor for the output of the microcircuit (common or output) through which heat is removed, it is desirable to make it as large as possible.
The assembled device is placed in a plastic box of suitable dimensions or in the battery compartment of the powered device. To dock with the charger, the adapter must be equipped with an appropriate socket (similar to that installed in a cell phone). It can be placed on printed circuit board with a stabilizer or fix it on one of the box walls.
The adapter does not require adjustment, you just need to check it in operation with the connecting wires that will be used to connect to the charger and the powered device. Self-excitation is eliminated by increasing the capacitance of capacitors C1 and C2.

LITERATURE
1. Biryukov S. Microcircuit voltage stabilizers for wide application. - Radio, 1999, No. 2, p. 69-71.
2. LD1117 Series. Low Drop Fixed and Adjustable Positive Voltage Regulators. - .
3. REG1117, REG1117A. 800mA and 1A Low Dropout (LDO) Positive Regulator 1.8V, 2.5V, 2.85V, 3.3V, 5V and Adjustable. - .
4. LM3480. 100 mA, SOT-23, Quasi Low-Dropout Linear Voltage Regulator. - .