Basic circuits of pulse network adapters for charging phones. Repair of charger for lithium batteries Chinese switching power supply 13003 circuits

The low-power switching power supply can be used in a wide variety of amateur radio designs. The circuit of such a UPS is particularly simple, so it can be repeated even by novice radio amateurs.

Main parameters of the power supply:
Input voltage - 110-260V 50Hz
Power - 15 Watt
Output voltage - 12V
Output current - no more than 0.7A
Operating frequency 15-20kHz

The initial components of the circuit can be obtained from available trash. The multivibrator used transistors of the MJE13003 series, but if desired, they can be replaced with 13007/13009 or similar. Such transistors are easy to find in switching power supplies (in my case, they were removed from a computer power supply).

The power supply capacitor is selected with a voltage of 400 Volts (in extreme cases, 250, which I strongly do not recommend)
The zener diode used was a domestic type D816G or an imported one with a power of about 1 watt.

Diode bridge - KTs402B, you can use any diodes with a current of 1 Ampere. Diodes must be selected with a reverse voltage of at least 400 volts. From the imported interior you can install 1N4007 (a complete domestic analogue of KD258D) and others.

The pulse transformer is a 2000NM ferrite ring, the dimensions in my case are K20x10x8, but large rings were also used, but I didn’t change the winding data, it worked fine. The primary winding (network) consists of 220 turns with a tap from the middle, the wire is 0.25-0.45 mm (there is no point anymore).

The secondary winding in my case contains 35 turns, which provides an output of about 12 Volts. The wire for the secondary winding is selected with a diameter of 0.5-1mm. The maximum power of the converter in my case is no more than 10-15 watts, but the power can be changed by selecting the capacitance of capacitor C3 (in this case, the winding data of the pulse transformer is already changing). The output current of such a converter is about 0.7A.
Select a smoothing capacitance (C1) with a voltage of 63-100 Volts.

At the output of the transformer, you should use only pulse diodes, since the frequency is quite high, conventional rectifiers may not cope. FR107/207 are perhaps the most affordable of the switching diodes, often found in network UPSs.

The power supply does not have any short circuit protection, so you should not short-circuit the secondary winding of the transformer.

I didn’t notice any overheating of the transistors; with an output load of 3 Watts (LED assembly), they are icy, but just in case, they can be installed on small heat sinks.

List of radioelements

The pulse stabilizer circuit is not much more complicated than the transformer one, but it is more difficult to configure. Therefore, for insufficiently experienced radio amateurs who do not know the rules of working with high voltage (in particular, never work alone and never adjust a switched-on device with both hands - only one!), I do not recommend repeating this scheme.

Schematic diagram

In Fig. 1. The electrical circuit of a pulse voltage stabilizer for charging cell phones (phone charger) is presented.

Rice. 1. Electrical circuit of a pulse voltage stabilizer for charging cell phones.

The circuit is a blocking oscillator implemented on transistor VT1 and transformer T1. Diode bridge VD1 rectifies the alternating mains voltage, resistor R1 limits the current pulse when turned on, and also serves as a fuse. Capacitor C1 is optional, but thanks to it the blocking generator operates more stably, and the heating of transistor VT1 is slightly less (than without C1).

When the power is turned on, transistor VT1 opens slightly through resistor R2, and a small current begins to flow through winding I of transformer T1. Thanks to inductive coupling, current also begins to flow through the remaining windings.

At the upper (according to the diagram) terminal of winding II there is a small positive voltage, through the discharged capacitor C2 it opens the transistor even more strongly, the current in the transformer windings increases, and as a result the transistor opens completely, to a state of saturation.

After some time, the current in the windings stops increasing and begins to decrease (transistor VT1 is completely open all this time). The voltage on winding II decreases, and through capacitor C2 the voltage at the base of transistor VT1 decreases.

It begins to close, the voltage amplitude in the windings decreases even more and changes polarity to negative. Then the transistor turns off completely. The voltage on its collector increases and becomes several times higher than the supply voltage (inductive surge), however, thanks to the chain R5, C5, VD4, it is limited to a safe level of 400...450 V.

Thanks to elements R5, C5, generation is not completely neutralized, and after some time the polarity of the voltage in the windings changes again (according to the principle of operation of a typical oscillating circuit). The transistor begins to open again. This continues indefinitely in a cyclical mode.

The remaining elements of the high-voltage part of the circuit assemble a voltage regulator and a unit for protecting transistor VT1 from overcurrent. Resistor R4 in the circuit under consideration acts as a current sensor. As soon as the voltage drop across it exceeds 1...1.5 V, transistor VT2 will open and close the base of transistor VT1 to the common wire (forcefully close it). Capacitor SZ accelerates the reaction of VT2. Diode VD3 is necessary for normal operation of the voltage stabilizer.

The voltage stabilizer is assembled on one microcircuit - an adjustable zener diode DA1.

For galvanic isolation of the output voltage from the network voltage, optocoupler VO1 is used. The operating voltage for the transistor part of the optocoupler is taken from winding II of transformer T1 and smoothed by capacitor C4.

As soon as the voltage at the output of the device becomes greater than the nominal one, current will begin to flow through the zener diode DA1, the optocoupler LED will light up, the collector-emitter resistance of phototransistor VO1.2 will decrease, transistor VT2 will open slightly and reduce the amplitude of the voltage at the base of VT1.

It will open weaker, and the voltage on the transformer windings will decrease. If the output voltage, on the contrary, becomes less than the nominal voltage, then the phototransistor will be completely closed and the transistor VT1 will “swing” at full strength. To protect the zener diode and LED from current overloads, it is advisable to connect a resistor with a resistance of 100...330 Ohms in series with them.

Setting up

The first stage, it is recommended to connect the device to the network for the first time through a 25 W, 220 V lamp, and without capacitor C1. The resistor R6 slider is set to the bottom (according to the diagram) position. The device is turned on and off immediately, after which the voltages on capacitors C4 and C6 are measured as quickly as possible.

If there is a small voltage across them (according to the polarity!), then the generator has started; if not, the generator does not work; you need to look for errors on the board and installation. In addition, it is advisable to check transistor VT1 and resistors R1, R4.

If everything is correct and there are no errors, but the generator does not start, swap the terminals of winding II (or I, but not both at once!) and check the functionality again.

Second stage: turn on the device and control with your finger (not the metal pad for the heat sink) the heating of transistor VT1, it should not heat up, the 25 W light bulb should not light up (the voltage drop across it should not exceed a couple of volts).

Connect some small low-voltage lamp to the output of the device, for example, rated for a voltage of 13.5 V. If it does not light, swap the terminals of winding III.

And at the very end, if everything works fine, check the functionality of the voltage regulator by rotating the slider of the trimming resistor R6. After this, you can solder in capacitor C1 and turn on the device without a current-limiting lamp.

The minimum output voltage is about 3 V (the minimum voltage drop at the DA1 pins exceeds 1.25 V, at the LED pins - 1.5 V).

If you need a lower voltage, replace the zener diode DA1 with a resistor with a resistance of 100...680 0m. The next setup step requires setting the device output voltage to 3.9...4.0 V (for a lithium battery). This device charges the battery with an exponentially decreasing current (from about 0.5 A at the beginning of the charge to zero at the end (for a lithium battery with a capacity of about 1 A/h this is acceptable)). In a couple of hours of charging mode, the battery gains up to 80% of its capacity.

Details and design

A special design element is a transformer.

The transformer in this circuit can only be used with a split ferrite core. The operating frequency of the converter is quite high, so only ferrite is needed for transformer iron. And the converter itself is single-cycle, with constant magnetization, so the core must be split, with a dielectric gap (one or two layers of thin transformer paper are laid between its halves).

It is best to take a transformer from an unnecessary or faulty similar device. In extreme cases, you can wind it yourself: core cross-section 3...5 mm2, winding I - 450 turns with a wire with a diameter of 0.1 mm, winding II - 20 turns with the same wire, winding III - 15 turns with a wire with a diameter of 0.6... .0.8 mm (for output voltage 4...5 V). When winding, strict adherence to the winding direction is required, otherwise the device will work poorly or not work at all (you will have to make efforts when setting it up - see above). The beginning of each winding (in the diagram) is at the top.

Transistor VT1 - any power of 1 W or more, collector current of at least 0.1 A, voltage of at least 400 V. The current gain h21e must be greater than 30. Transistors MJE13003, KSE13003 and all other type 13003 of any company are ideal. As a last resort, domestic transistors KT940, KT969 are used.

Unfortunately, these transistors are designed for a maximum voltage of 300 V, and at the slightest increase in the mains voltage above 220 V they will break through. In addition, they are afraid of overheating, i.e. they need to be installed on a heat sink. For transistors KSE13003 and MJE13003, a heat sink is not needed (in most cases, the pinout is the same as that of domestic KT817 transistors).

Transistor VT2 can be any low-power silicon, the voltage on it should not exceed 3 V; the same applies to diodes VD2, VD3. Capacitor C5 and diode VD4 must be designed for a voltage of 400...600 V, diode VD5 must be designed for the maximum load current.

The diode bridge VD1 must be designed for a current of 1 A, although the current consumed by the circuit does not exceed hundreds of milliamps - because when turned on, a rather powerful surge of current occurs, and it is impossible to increase the resistance of resistor R1 to limit the amplitude of this surge - it will get very hot.

Instead of the VD1 bridge, you can install 4 diodes of type 1N4004...4007 or KD221 with any letter index. Stabilizer DA1 and resistor R6 can be replaced with a zener diode, the voltage at the output of the circuit will be 1.5 V greater than the stabilization voltage of the zener diode.

The "common" wire is shown in the diagram for graphical purposes only and should not be grounded and/or connected to the device chassis. The high voltage part of the device must be well insulated.

The elements of the device are mounted on a board made of foil fiberglass in a plastic (dielectric) case, in which two holes are drilled for indicator LEDs. A good option (used by the author) is to design the device board in a housing made from a used A3336 battery (without a step-down transformer).

Literature: Andrey Kashkarov - Electronic homemade products.

Everyone knows that there is such an operation as pre-sale preparation of goods. A simple but very necessary action. By analogy with it, I have long been using pre-use preparation of all purchased Chinese-made goods. There is always the possibility of modification in these products, and I note that it is really necessary, which is a consequence of the manufacturer saving on high-quality material for its individual elements or not installing them at all. Let me be suspicious and suggest that all this is not accidental, but is an integral element of the manufacturer’s policy aimed ultimately at reducing the service life of the manufactured product, which results in an increase in sales. Having decided to actively use a miniature electric massager (made in China, of course), I immediately noticed its power supply, which looks like a mobile phone charger and even has an inscription COURIER CHARGER- mobile charger. Having an OUTPUT of 5 volts and 500 mA. Without even being convinced of its serviceability, I took it apart and looked at the contents.

The electronic components installed on the board and especially the zener diode at the output indicated that this was indeed a power supply. By the way, I don’t consider the absence of a diode bridge to be a positive thing.

The connected load, in the form of two 2.5 V light bulbs in series, with a current consumption of 150 mA, detected 5.76 V at the output. The device is designed to be powered by three AA batteries - 4.5 V, I think acceptable, and 5 V from the adapter, but anything else, in this particular case, is clearly useless.

After searching for a schematic on the Internet, I chose to draw, based on a photo taken in advance, a printed circuit board with the electronic components located on it.

Adapter circuit and conversion

The image of the printed circuit board made it possible to draw the existing power supply circuit. The CHY 1711 transistor optocoupler, C945, S13001 transistors and other components did not allow me to call the circuit primitive, but with the existing ratings of some components and the absence of others, it did not suit me.

A 160 mA fuse was introduced into the new circuit, and instead of the existing rectifier, a diode bridge consisting of 4 1N4007 diodes was introduced. The value of the zener diode VD3 controlling the optocoupler has been changed from 4V6 to 3V6, which should reduce the output voltage to the desired level.

There was enough free space on the board so that it was not difficult to implement the planned changes. The newly assembled power supply had an output voltage of almost 4.5 volts.

And current output up to 300 mA inclusive.

As a result, some additional electronic components and time devoted to interesting work gave me the opportunity to have a decent power supply that I hope will serve faithfully for a long time. Babay was involved in debugging the power supply.

I present another device from the “Don’t Take!” series.
The kit includes a simple microUSB cable, which I will test separately with a bunch of other cords.
I ordered this charger out of curiosity, knowing that in such a compact case it is extremely difficult to make a reliable and safe 5V 1A mains power device. The reality turned out to be harsh...

It came in a standard bag with bubble wrap.
The case is glossy, wrapped in protective film.
Overall dimensions with plug 65x34x14mm








The charger immediately turned out to be inoperative - a good start...
At first, the device had to be disassembled and repaired in order to be able to test it.
It is very easy to disassemble - on the latches of the plug itself.
The defect was discovered immediately - one of the wires to the plug fell off, the soldering turned out to be of poor quality.


The second soldering is no better


The installation of the board itself was done normally (for the Chinese), the soldering was good, the board was washed.






Real device diagram


What problems were found:
- Quite weak connection between the fork and the body. The possibility of her remaining disconnected from the socket is not excluded.
- Lack of input fuse. Apparently those same wires to the plug are the protection.
- Half-wave input rectifier - unjustified savings on diodes.
- Small capacitance of the input capacitor (2.2 µF/400V). The capacity is clearly insufficient for the operation of a half-wave rectifier, which will lead to increased voltage ripple across it at a frequency of 50 Hz and to a decrease in its service life.
- Lack of input and output filters. Not a big loss for such a small and low-power device.
- The simplest converter circuit using one weak transistor MJE13001.
- A simple ceramic capacitor 1nF/1kV in the noise suppression circuit (shown separately in the photo). This is a gross violation of device security. The capacitor must be of at least Y2 class.
- There is no damper circuit for suppressing reverse emissions of the primary winding of the transformer. This impulse often breaks through the power key element when it heats up.
- Lack of protection against overheating, overload, short circuit, and increased output voltage.
- The overall power of the transformer clearly does not reach 5W, and its very miniature size casts doubt on the presence of normal insulation between the windings.

Now testing.
Because The device is not inherently safe; the connection was made through an additional mains fuse. If something happens, at least it won’t burn you and won’t leave you without light.
I tested it without the housing so that I could control the temperature of the elements.
Output voltage without load 5.25V
Power consumption without load less than 0.1 W
Under a load of 0.3A or less, charging works quite adequately, the voltage maintains a normal 5.25V, the output ripple is insignificant, the key transistor heats up within normal limits.
Under a load of 0.4A, the voltage begins to fluctuate slightly in the range of 5.18V - 5.29V, the ripple at the output is 50Hz 75mV, the key transistor heats up within normal limits.
Under a load of 0.45A, the voltage begins to noticeably fluctuate in the range of 5.08V - 5.29V, the ripple at the output is 50Hz 85mV, the key transistor begins to slowly overheat (burns your finger), the transformer is lukewarm.
Under a load of 0.50A, the voltage begins to fluctuate greatly in the range of 4.65V - 5.25V, the ripple at the output is 50Hz 200mV, the key transistor is overheated, the transformer is also quite hot.
Under a load of 0.55A, the voltage jumps wildly in the range of 4.20V - 5.20V, the ripple at the output is 50Hz 420mV, the key transistor is overheated, the transformer is also quite hot.
With an even greater increase in load, the voltage drops sharply to indecent values.

It turns out that this charger can actually produce a maximum of 0.45A instead of the declared 1A.

Next, the charger was collected in the case (along with the fuse) and left in operation for a couple of hours.
Oddly enough, the charger did not fail. But this does not mean at all that it is reliable - having such circuitry it will not last long...
In short circuit mode, charging quietly died 20 seconds after switching on - the key transistor Q1, resistor R2 and optocoupler U1 broke. Even the additionally installed fuse did not burn out.

For comparison, I’ll show you what a simple Chinese 5V 2A tablet charger looks like inside, manufactured in compliance with the minimum permissible safety standards.

Taking this opportunity, I inform you that the lamp driver from the previous review has been successfully modified and the article has been updated.

Most modern network chargers are assembled using a simple pulse circuit, using one high-voltage transistor (Fig. 1.18) according to a blocking generator circuit.

Unlike simpler circuits using a step-down 50-Hz transformer, the transformer for pulse converters of the same power is much smaller in size, which means the size, weight and price of the entire converter are smaller. In addition, pulse converters are safer - if in a conventional converter, when the power elements fail, the load receives a high unstabilized (and sometimes even alternating) voltage from the secondary winding of the transformer, then in case of any malfunction of the pulse converter (except for the failure of the feedback optocoupler - but it is usually very well protected) there will be no voltage at all at the output.

Rice. 1.18. A simple pulse blocking oscillator circuit

A description of the operating principle and calculation of circuit elements of a high-voltage pulse converter (transformer, capacitors, etc.) can be read at http://www.nxp.com/acrobat/applicationnotes/AN00055.pdf (1 MB).

Operating principle of the device

The alternating mains voltage is rectified by diode VD1 (although sometimes the generous Chinese install as many as 4 diodes in a bridge circuit), the current pulse when turned on is limited by resistor R1. Here it is advisable to install a resistor with a power of 0.25 W - then if overloaded, it will burn out, acting as a fuse.

The converter is assembled on transistor VT1 using a classic flyback circuit. Resistor R2 is needed to start generation when power is applied; in this circuit it is optional, but with it the converter works a little more stable. Generation is supported by capacitor C1, included in the PIC circuit on winding I; the generation frequency depends on its capacitance and the parameters of the transformer. When the transistor is unlocked, the voltage at the lower terminals of windings I and II is negative, at the upper terminals it is positive, the positive half-wave through capacitor C1 opens the transistor even more, and the voltage amplitude in the windings increases.

The transistor opens like an avalanche. After some time, as capacitor C1 charges, the base current begins to decrease, the transistor begins to close, the voltage at the upper terminal of winding II in the circuit begins to decrease, through capacitor C1 the base current decreases even more, and the transistor closes like an avalanche. Resistor R3 is necessary to limit the base current during circuit overloads and surges in the AC network.

At the same time, the amplitude of the self-induction EMF through the diode VD4 recharges the capacitor SZ - that is why the converter is called flyback. If you swap the terminals of winding III and recharge the capacitor SZ during the forward stroke, then the load on the transistor VT1 will sharply increase during the forward stroke (it may even burn out due to too much current), and during the reverse stroke the self-induction EMF will be unspent and released at the collector junction of the transistor - that is, it can burn out from overvoltage.

Therefore, when manufacturing the device, it is necessary to strictly observe the phasing of all windings (if you mix up the terminals of winding II, the generator simply will not start, since capacitor C1 will, on the contrary, disrupt generation and stabilize the circuit).

The output voltage of the device depends on the number of turns in windings II and III and on the stabilization voltage of the zener diode VD3. The output voltage is equal to the stabilization voltage only if the number of turns in windings II and III is the same, otherwise it will be different. During the reverse stroke, capacitor C2 is recharged through diode VD2, as soon as it is charged to approximately -5 V, the zener diode will begin to pass current, the negative voltage at the base of transistor VT1 will slightly reduce the amplitude of the pulses on the collector, and the output voltage will stabilize at a certain level. The stabilization accuracy of this circuit is not very high - the output voltage varies within 15...25% depending on the load current and the quality of the zener diode VD3.

Alternative device option

The circuit of a better (and more complex) converter is shown in Fig. 1.19.

To rectify the input voltage, a diode bridge VD1 and a capacitor C1 are used; the resistor R1 must have a power of at least 0.5 W, otherwise at the moment of switching on, when charging the capacitor C1, it may burn out. The capacitance of capacitor C1, in microfarads, must be equal to the power of the device, in watts.

The converter itself is assembled according to the already familiar circuit using transistor VT1. The emitter circuit includes a current sensor on resistor R4 -

Rice. 1.19. Electrical circuit of a more complex converter

as soon as the current flowing through the transistor becomes so large that the voltage drop across the resistor exceeds 1.5 V (with the resistance indicated on the diagram being 75 mA), transistor VT2 opens slightly through diode VD3 and limits the base current of transistor VT1 so that its collector current does not exceeded the above 75 mA. Despite its simplicity, this protection circuit is quite effective, and the converter turns out to be almost eternal even with short circuits in the load.

To protect transistor VT1 from emissions of self-induction EMF. A smoothing chain VD4-C5-R6 has been added to the circuit. The VD4 diode must be high-frequency - ideally BYV26C, a little worse - UF4004...UF4007 or 1N4936, 1N4937. If there are no such diodes, it’s better not to install a chain at all!

Capacitor C5 can be anything, but it must withstand a voltage of 250...350 V. Such a chain can be installed in all similar circuits (if it is not there), including the circuit in Fig. 1.18 - it will noticeably reduce the heating of the switch transistor housing and significantly “extend the life” of the entire converter.

The output voltage is stabilized using a zener diode DA1 located at the output of the device; galvanic isolation is provided by an optocoupler VOl. The TL431 microcircuit can be replaced with any low-power zener diode, the output voltage is equal to its stabilization voltage plus 1.5 V (voltage drop across the optocoupler LED VOl); To protect the LED from overloads, a small resistance resistor R8 is added. As soon as the output voltage becomes slightly higher than expected, current will flow through the zener diode, the optocoupler LED VOl will begin to glow, its phototransistor will open slightly, the positive voltage from capacitor C4 will slightly open transistor VT2, which will reduce the amplitude of the collector current of transistor VT1. The instability of the output voltage of this circuit is less than that of the previous one and does not exceed 10...20%; also, thanks to capacitor C1, there is practically no 50 Hz background at the output of the converter.

It is better to use an industrial transformer in these circuits, from any similar device. But you can wind it yourself - for an output power of 5 W (1 A, 5 V), the primary winding should contain approximately 300 turns of wire with a diameter of 0.15 mm, winding II - 30 turns of the same wire, winding III - 20 turns of wire with a diameter of 0 .65 mm. Winding III must be very well insulated from the first two; it is advisable to wind it in a separate section (if any). The core is standard for such transformers, with a dielectric gap of 0.1 mm. In extreme cases, you can use a ring with an outer diameter of approximately 20 mm.