Power source - from a cell phone charger
I. NECHAYEV, Kursk
Small-sized portable 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 power supply. Such a source (in common parlance it is called an adapter) is not difficult to purchase or make yourself; fortunately, there are many of them described in 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 cellular subscribers in the Russian Federation exceeded 115 million). Its charger is used for its intended purpose (to charge the phone battery) only a few hours a week, and the rest of the time is inactive. The article describes how to adapt it to power small-sized equipment.
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 an alternating current network. If you don’t have a ready-made power supply with the required output voltage, you don’t have to buy or assemble such a unit yourself; you can use a cell phone charger for this purpose, which many people have today.
However, you cannot directly connect it to a radio or player. The fact is that most chargers included with a cell phone are an unstabilized rectifier, the output voltage of which (4.5...7 V at a load current of 0.1...O.ZA) exceeds that required to power a small-sized apparatus. The problem can be easily solved. To use the charger as a power supply, you must connect a voltage stabilizer adapter between it and the device.
As the name itself says, the basis of such a device should be a voltage stabilizer. It is most convenient to assemble it on a specialized microcircuit. The large range and availability of integrated stabilizers allow us to produce a wide variety of adapter options.
The schematic diagram of the adapter-voltage stabilizer is shown in Fig. 1. DA1 chip is selected 
depending on the required output voltage and current consumed by the load. The capacitance 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 the charger can supply such current, the KR142EN5A (output voltage - 5 V), KR1158ENZV, KR1158ENZG (3.3 V), KR1158EN5V, KR1158EN5G (5 V) microcircuits can be used as DA1, as well as five-volt imported 7805, 78M05. Microcircuits 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 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 housing (S - SOT-223, D - S0-8, V - TO-220), and the two-digit number following it indicates the nominal value of the output voltage in tenths of volts (12 - 1.2 V, 18 - 1.8 V, etc.). The number attached through a hyphen in the designation of 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 acceptable to use stabilizer microcircuits with adjustable output voltage, for example, KR142EN12A, LM317T. In this case, you can get any output voltage value from 1.2 to 5...6 V.
When powering equipment that consumes a small current (30...100 mA), for example, small-sized VHF FM radios, the adapter can use the KR1157EN5A, KR1157EN5B, KR1157EN501A, KR1157EN501B, KR1157EN502A, KR1157EN502B, KR11 microcircuits 58EN5A, KR1158EN5B (all with rated output voltage 5 V ), KR1158ENZA, KR1158ENZB (3.3 V). Drawing of a possible version of the adapter printed circuit board using
The use of microcircuits of the latest series is shown in Fig. 3. Capacitors C1 and C2 - small-sized oxide capacitors of any type with a capacity of 10 μF.
The dimensions of the adapter can be significantly reduced by using miniature microcircuits of the LM3480-xx series (the last two digits indicate the output voltage). They are produced in the SOT-23 package (see Fig. 2.6). The printed circuit board drawing 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 of adapters mounted on boards manufactured in accordance with Fig. 3 and 4, shown in Fig. 5. 
It should be noted that the foil on the board can serve as a heat sink. Therefore, it is advisable to make the area of the conductor for the microcircuit terminal (common or output), through which heat is removed, 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 connect to the charger, the adapter must be equipped with an appropriate socket (similar to the one installed in a cell phone). It can be placed on a printed circuit board with a stabilizer or mounted on one of the walls of the box.
The adapter does not require any installation; you just need to check its 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. -
Surely every car enthusiast has a battery charger. And not every device has a built-in good stabilizer with an output filter, which manifests itself in a voltage drop at high currents. I suggest you assemble a simple circuit consisting of a bank of capacitors, the ROLL stabilizer itself and 2 transistors. Such a converter will give you up to 6 Amps of current at the output. In general, this circuit can be used for a power supply as a filter and voltage stabilizer. The voltage stabilizer will protect against voltage drops under heavy temporary loads and will try to maintain a certain value, and the filter will remove excess ripple, which will improve the performance of the power supply. In short, see for yourself how to use this circuit, because you can also add it to the power supply to improve the characteristics and to the charger. Below you see a diagram of such a device as an attachment - a stabilizer for a car charger:
Let's start looking at the diagram in order. At the very beginning we see four capacitors C1, C2, C3, C4, which perform a large function in filtering ripples, and to a lesser extent in stabilizing the current. In fact, if you install a capacitor of a very large capacity, then there is no need to assemble the stabilizer at all - we will already have a ready-made stabilizer. The large capacitance of capacitors can be compared with a conventional battery, because the battery already has stabilized power. And capacitors are filled with electrolyte, the electrolyte is charged, which means they are similar to batteries. That is, for example, we connected a low-frequency amplifier and in the bass (when the current reaches its peak value) the bass sags, becomes hoarse and not clear, and if we connect a battery of capacitors, then when the current increases in the bass, the capacitor will simply give up some of the energy and the bass will be clear.
In general, choose for yourself which stabilizer to make. You can calculate the energy of a capacitor for the required current using formulas that can be searched on the Internet. Such a stabilizer + filter will cost about 100-150 thousand microfarads and is expensive. According to this scheme, the sum of four smoothing capacitors should be 20 thousand microfarads. Further on the diagram we see a voltage stabilizer assembled on a KRENK. The stabilized current will depend on the brand of Krenki, and the brand can be selected from the table. The transistors form a powerful emitter follower, as a result of which this circuit is capable of stabilizing the voltage up to 5-6 Amperes.
If you want to make the circuit more powerful, you can add 2 more transistors, then such a stabilizer will be able to stabilize the current to 10-11 Amperes. That is, we connect two more transistors with the bases in parallel to the ROLL second leg, two collectors to the plus of the input voltage and emitters to the output. Next, a capacitor is installed as a filter with a larger capacity (6000 microfarads) and then two small capacitance ceramic capacitors of 0.1, which will suppress high-frequency interference. Transistors must be installed on a heat sink - a radiator. When charging the battery, constantly monitor how the radiator heats up. If it gets very hot, you can install a cooler on the radiator to cool it down. All transistors are installed on the heat sink! The heat sink is usually made of aluminum. For better thermal conductivity, we buy thermal conductive paste, apply a thin layer to the radiator and transistor, wait 5 minutes and press tightly, tightening it with a nut.
The stabilizer is connected to the charger rectifier. The output of the stabilizer is connected to the battery being charged. It is recommended to install a 5-6 Ampere fuse at the output to protect the circuit from short circuits. Also, if you want to install a voltage alarm, i.e. When you turn it on, you can see that the device is working, then install an LED in parallel through a resistor. When devices are connected to the network, the LED will light up. By changing the resistance of the resistor, achieve the optimal brightness of the LED. That's it, the circuit is ready and ready to use.
The technological process does not stand still, and modern phone manufacturers are releasing more and more sophisticated models with many new features. Active improvement of software and hardware functionality leads to the fact that the battery life of the device is reduced. Large RAM, powerful processes, multi-inch touch screens and powerful cameras all contribute to the fact that batteries are discharged quite quickly. This is why it is important to have a reliable memory. It’s great if the original charger has been preserved, but what if it’s lost or broken? Then buying a new one raises the question of not only preserving the functionality of the phone, but also your own comfort.
Everyone has experienced their smartphone running out of power at the most inopportune moment. This is especially scary when there is sorely not enough time to recharge. At such moments, the first charger that comes to hand is grabbed, connected and the countdown begins. Sometimes the process happens quickly, and often it takes a treacherously long time. The result is sad - after some time there is no connection again. Today we’ll figure out how memory devices differ and how to make the right choice.
Charger type
Before purchasing, many people ask themselves which memory is better to choose: original, analog or universal? Many people buy the original, which means they do not worry about the compatibility of the device with gadgets, the speed and features of charging, as well as various risks (cheap chargers that are sold in tents in markets may well lead to strong heating of the battery). But it is not always possible to buy an original device, then a high-quality analogue will be the best option. It contains a list of compatible device models, as well as technical characteristics that are identical to those of the original.
Power connector
The memory can have different connectors:
USB. Such devices are universal and suitable for most modern gadgets that support the USB standard.
USB x2. This is the best option when there are problems with access to a power outlet. Using this charger you can charge your tablet and smartphone at the same time. The only drawback is the low charging speed of the battery.
Micro USB and Mini USB. They are suitable for most smartphones, including Windows Phone, Android, and Android tablets. Micro USB has been introduced in the EU as a single standard since 2011.
Lightning 8-pin MFI. It is suitable for charging fifth-generation devices from Apple: iPod Touch and iPhone 5.
Lightning 8-pin. It is compatible with most Apple iPad, iPhone and iPod models.
DC jack 3.5 mm. It is suitable for charging Nokia 1100, 3300, 5100, 6310, 6670, 6822, 7200, 7210, 7250, 7710, 8800, 9210, 9300, 9500, E60 and E70 mobile devices.
USB/Lightning These chargers are suitable for Apple iPhone 5 and 6.
Fast Port. It is compatible with Sony Ericsson K750 and W800 phones.
18-pin. This connector is designed for charging LG phones.
jack 3.5 mm, DC jack 2.5 mm and DC jack 2.0 mm. It is suitable for charging various mobile equipment: phones, headsets, tablets, players. Using adapters you can also connect Apple equipment.
M20pin. This connector is suitable for charging Samsung C170, D800, E250, E900 and U600.
30 pin. It is suitable for powering Samsung branded equipment.
Output current
Chargers with maximum output current are suitable for servicing any gadgets. In this case, the current consumption rarely exceeds 2100 mA. Such chargers are the most universal solution. In order not to make a mistake with your purchase, pay attention to the parameters of the original memory for the device. To do this, just look at its body and the numbers next to “output” or “output”. If there is no original memory, then perhaps this data is mentioned in the instructions for the tablet or smartphone.
The maximum charge current is determined by the controller of the device being charged, so do not be afraid to connect a charger with a higher current than the gadget requires. He will simply take as much as he needs - nothing will burn or break.
But on the contrary, if the charger produces fewer amperes than the gadget being charged requires, then charging will proceed much slower.
If you don’t know and there is no way to find out how much current your gadget consumes, then when choosing universal chargers, buy a charger with the highest output current.
There is a little trick - in order to speed up charging your smartphone, it is recommended to switch it to “airplane mode”/“airplane mode”/offline mode. At the same time, all unnecessary modules and applications are disabled, and the phone will charge about 15% faster.
Number of standard USB connectors
A number of chargers have either 2 standard USB connectors. Devices of the second type are quite convenient - you can connect several gadgets to one outlet for charging at once. Such devices are great for trips and travel. This will reduce the number of items in your luggage, and you won't have to search for multiple power outlets at the hotel.
Cable included
Depending on the charger model, the cable may be:
removable;
non-removable;
absent.
The weakest link in the charger is the cable. If it is non-removable, then if it breaks, it is almost impossible to restore the functionality of the device. If it is removable, then the adapter itself, which is plugged into the network, can be used further by simply purchasing an additional wire.
When choosing a charger, it is better to give preference to proven brands. For questionable devices, the cable can reduce charging efficiency by up to 75%. And this is not only a loss of electricity, but also of your time. In addition, such cables can break or come off the connector, which ultimately remains in the device. This leads to a short circuit and failure of the device.
Fast charging
Some charger models have fast charging. She may be:
Quick Charge 2.0;
Quick Charge 3.0;
Pump Express+ 2.0.
According to the developers of Quick Charge technology, battery charging can be accelerated by up to 75%. In the first few minutes, smartphones that are compatible with Quick Charge are charged for several hours of use. This is really convenient in the modern rhythm of life - you run into a cafe, plug in your gadget, drink a cup of coffee and leave with a phone with a decent battery charge.
The key difference between Quick Charge 3.0 technology and 2.0 is the presence of the INOV function or intelligent determination of the optimal voltage. Depending on the progress of the battery charge, the required current strength gradually decreases. This allows you to minimize wasted energy during recharging.
Using a special adapter with the Pump Express+ 2.0 function, you can fully charge your smartphone battery 1.5 times faster compared to a standard charger.
Price issue
Today, chargers are available in a wide price range. So, having spent:
From 65 to 300 rubles you can buy branded memory for devices of various brands (Sony Ericsson, Samsung, LG, Apple or Nokia). They can be without a wire, as well as with a removable or non-removable wire.
From 300 to 1000 rubles you can purchase universal chargers in a durable case with two USB connectors. They will become an indispensable companion when traveling and in everyday life.
for more than 1000 rubles you will receive reliable and practical chargers from leading brands. A number of models have the Quick Charge 2.0 or Quick Charge 3.0 fast charging function, in which the charging power is increased by voltage rather than current. Which is absolutely safe for the gadget, because... it does not overheat.
At first glance, the power supply is no different from the charger. Especially if the first one has a rectifier circuit that allows you to convert alternating voltage to direct voltage.
This is why some, without going into details, try to use power supplies to charge batteries and chargers to constantly power devices. Any equipment must be used for its intended purpose, and then the result of its operation will correspond to the characteristics declared by the manufacturer.
What fundamentally distinguishes a charger from a power supply?
- In order for a device to be called a power supply, it only needs to have a simple transformer that has one primary and one secondary winding. Everything is already a power supply. Such a transformer will produce on the secondary winding the voltage that is necessary to power the device. It will also be variable, but the voltage will be lower. Most electronic devices have DC power supply. To do this, the step-down transformer is equipped with a rectification circuit (often just a diode bridge) and, in principle, this is enough for the power supply.
- The charger is a little more complicated. Its circuit diagram is more complex and its function is mainly to generate a pulse voltage that charges the batteries. Since it is pulsed rather than direct current that is optimal for charging. The power supply is a ripple-stabilized voltage.
- By its principle, the power supply does not accept short circuits. For a charger, a short circuit is, one might say, its “work”
- The main data “readable” from these devices is that for the power supply it is a constant voltage that does not change with increasing load, but for the charger the voltage can fluctuate, but the charging current must strictly correspond to the capacity of the device being charged, otherwise the batteries can be damaged. Typically, the charging current should be equal to 1/10 of the battery capacity.
Taking this into account, we understand that not every power supply will “take care” of the current required for the battery, which can lead to damage to the latter. This means that it is better not to use power supplies for charging.
To summarize in Russian, the power supply is a voltage source, and the charger is more of a current source.
Before experimenting with replacing a charger with a power supply and vice versa, you need to know all the characteristics of these devices. Then decide on the possibility of interchange.
