Hello Habra Gentlemen and Habra Ladies!
I think some of you are familiar with the situation:
“Car, traffic jam, N-th hour behind the wheel. The communicator with the navigator running for the third time beeps about the end of the charge, despite the fact that it is always connected to the charger. And you, as an evil, are absolutely not guided in this part of the city. "
Next, I will talk about how, having moderately straight arms, a small set of tools and a little money, to build a universal (suitable for charging with a nominal current, both Apple and all other devices), car USB charger for your gadgets.

CAUTION: There are a lot of photos under the cut, a little work, no LUT and no happy end (not yet).

Author, what for all this?

Some time ago, the story described in the prologue happened to me, a Chinese usb double, absolutely shamelessly let my smart discharge during navigation, out of the declared 500mA it gave out about 350 to both sockets. I must say I was very angry. Well, okay - a fool himself, I decided, and on the same day, in the evening, he was ordered on eBay car charger on 2A, which rested in the depths of the Sino-Israeli Post Office. By a lucky coincidence, I had a DC-DC step down converter with an output current of up to 3 A and I decided to build a reliable and universal charger for a car on its basis.

A little about chargers.
Most of the chargers that are on the market, I would divide into four types:
1. Apple - sharpened for Apple devices, equipped with a small charging trick.
2. Conventional - focused on most gadgets, which have enough short-circuited DATA + and DATA- to consume the rated charge current (the one that is stated on the charger of your gadget).
3. Clueless - with DATA + and DATA- hanging in the air. In this regard, your device decides that it is a USB hub or a computer and does not consume more than 500 mA, which negatively affects the charging speed or even if it is absent under load.
4. Sly%! $ & E - since they have a microcontroller inside them, which tells the device that something from the category that the notorious Kipling's hero told the animals - "You and I are of the same blood," checks the originality of the charging. For all other devices, they are the third type of memory.

The last two options, for obvious reasons, I think are not interesting and even harmful, so we will focus on the first two. Since our charger must be able to charge both apple and all other gadgets, we use two USB outputs, one will be focused on Apple devices, the second on all the others. I will only note that if you mistakenly connect the gadget to a USB outlet that is not intended for it, nothing terrible will happen, it will just take the same notorious 500mA.
So, the goal: "With a little work with your hands, get a universal charger for the car."

What do we need

1.First, let's figure out the charge current, usually it's 1A for smartphones and about 2 Amperes for tablets (by the way, my Nexus 7, for some reason, doesn't take more than 1.2A from its own charge). In total, for the simultaneous charging of an average tablet and a smartphone, we need a current of 3A. This means that the DC-DC converter that I have in stock is fine. I must admit that a 4A or 5A converter would be better suited for these purposes, so that the current would be enough for 2 tablets, but I could not find compact and inexpensive solutions, and even time was running out.
So I used what it was:
Input voltage: 4-35V.
Output voltage: 1.23-30V (adjustable by potentiometer).
Maximum output current: 3A.
Type: Step Down Buck converter.

2. USB socket, I used a double one, which I dropped from the old USB hub.

You can also use regular sockets from a USB extension cable.

3. Prototyping board. In order to solder a USB socket to something and assemble a simple charging circuit for Apple.

4. Resistors or resistances, as you like and one LED. Only 5 pieces, 75 kOhm, 43 kOhm, 2 with 50 kOhm nominal and one at 70 Ohm. On the first 4, the Apple charging circuit is built, I used 70 Ohm to limit the current on the LED.

5. Housing. I found a Mag-Lite flashlight case in the bins of my homeland. In general, a black toothbrush case would be ideal, but I did not find one.

6. Soldering iron, rosin, solder, wire cutters, drill and an hour of free time.

We collect charging

1. First of all, I short-circuited the DATA + and DATA- pins on one of the sockets:

* I apologize for the harshness, I got up early and my body wanted to sleep, and my brain wanted to continue the experiment.

This will be our socket for non-apple gadgets.

2. Cut off the size of the breadboard we need and mark and drill holes in it for the mounting feet of the USB socket, while checking that the contact feet match the holes in the board.

3. Insert the socket, fix it and solder it to the breadboard. We close the + 5V contacts of the first (1) and second (5) sockets with each other, we do the same with the GND contacts (4 and 8).

Photo for clarification only, contacts are already soldered on the breadboard

4. Solder the following circuit on the remaining two contacts DATA + and DATA-:

To observe the polarity, we use the USB pinout:

I got it like this:

Do not forget to adjust the output voltage, using a screwdriver and a voltmeter, set 5 - 5.1V.

I also decided to add an indication to the circuit USB power, in parallel to + 5V and GND, I soldered yellow ice with a 70Ω resistor to limit the current.

An earnest request to people with a fine mental organization and other lovers of beauty: "Do not look at the next picture, because the soldering is a curve."

I'm brave!

5. We fix the converter board on our breadboard. I did this using the legs from the same resistors, soldering them into the contact holes on the converter board and on the breadboard.

6. Solder the outputs of the converter to the corresponding inputs on the USB socket. Observe the polarity!

7. We take the case, mark and drill holes for fastening our board, mark and cut out a place for a USB socket and add holes for ventilation opposite the converter microcircuit.

We fasten the breadboard with bolts to the case and we get the following box:

In the Machine it looks like this:

Tests

Further, I decided to check whether my devices will really consider that they are being charged from the native charger. And at the same time measure the currents.
Power is provided by a power supply unit from an old 24V 3.3A printer.
I measured the current before going to USB.

Looking ahead, I will say that all the devices I have have recognized the charging.
To USB socket number one (which is designed for different gadgets) I connected:
HTC Sensation, HTC Wildfire S, Nokia E72, Nexus 7, Samsung Galaxy ACE2.
For the Sensation and Nexus 7, I checked the charging times, starting at 1% and charging up to 100%.
The smartphone was charged in 1 hour 43 minutes (Anker 1900 mAh battery), I should note that it takes about 2 hours to charge from a standard charge.
The tablet was charged in 3 hours 33 minutes, which is half an hour longer than charging from the mains (I charged only one device at a time).

To both Android devices we took the maximum out of charging, I had to solder a small adapter (which I connected to apple USB), HTC Sensation was connected to it.

I connected to USB socket number two: Ipod Nano, Ipod Touch 4G, Iphone 4S, Ipad 2. Since it is ridiculous to charge the Nano with such a thing - it took a maximum of 200 mA from me, tested the Touch 4g and the iPad. The iPod took 1 hour and 17 minutes to charge from zero to 100% (though with the iPad 2). The iPad 2 took 4 hours and 46 minutes (one).

As you can see, the Iphone 4S consumes its rated current with pleasure.

By the way, Ipad 2 surprised me, it absolutely did not shy away from circuits with shorted date contacts and consumed absolutely the same currents as from the socket intended for it.

Charging process and conclusions

To begin with, let me remind you that all devices that use lithium batteries have a charge controller available. It works according to the following scheme:

The graph is averaged and may vary for different devices.

As you can see from the graph, at the beginning of the charging cycle, the controller allows you to charge with the maximum allowable current for your device and gradually reduces the current. The charge level is determined by voltage, the controllers also monitor the temperature and turn off charging at high values ​​of the latter. Charge controllers can be located in the device itself, in the battery or in the charger (very rarely).
You can read more about charging lithium cells.

Actually, here we come to the moment why this topic is called: "Attempt number of times." The fact is that the maximum that I managed to squeeze out of charging is: 1.77A

Well, the reason, in my opinion, is not an optimally selected inductor, which in turn does not allow the Buck - converter to give out its maximum current. I thought about replacing it, but I don't have a tool for SMD soldering and is not expected in the near future. This is not a mistake of the ebay board designers, it is just a feature of this circuit as it is oriented to different input and output voltages. Under such conditions, it is simply impossible to deliver the maximum current over the entire voltage range.

As a result, I got a device that can charge two smartphones at the same time or one tablet in the car in a reasonable amount of time.

In connection with the foregoing, it was decided to leave this charge as it is and assemble a new one, completely with our own hands, on the basis of a more powerful converter LM2678,
which in the future will be able to "feed" two tablets and a smartphone at the same time (5A output). But more on that next time!

P.S .:
1. The text may contain punctuation, grammatical and semantic errors, please report them in a personal message.
2. Thoughts, ideas, technical corrections and CU from more experienced comrades - on the contrary, are welcome in the comments.
3. I apologize for possible technical inaccuracies. until recently I was not engaged in electronics and circuitry.
Thank you for your attention, Good luck to everyone and inexhaustible optimism!

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. The 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 several tens of hours with the display off or to play several hours of video or several hours of reading. e-books... If the mains outlet is not available or due to bad weather or other reasons the power supply is disconnected for a long time, then various mobile devices with color displays will have to be powered from built-in energy sources.

Considering that such devices consume a lot of current, their batteries may be discharged before the moment when electricity is available from the wall outlet. If you do not want to immerse yourself in primeval silence and peace of mind, then a backup autonomous energy source can be provided for powering pocket devices, which will help out as during a long trip to wildlife, and in case of man-made or natural disasters, when your settlement may be for several days or weeks without power supply.

Diagram of a mobile charger without a 220V network

The device is a linear compensation-type voltage regulator with a low saturation voltage and a very low intrinsic current consumption. As a source of energy for this stabilizer can be a simple battery, storage battery, solar or manual electric 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.

A self-resetting fuse protects the gimbal and battery from overload. The reverse-connected diode VD1 protects the device from polarity reversal of the supply voltage. As the supply voltage increases, the output voltage also tends to increase. To keep the output voltage stable, a regulating unit assembled on VT1, VT4 is used.

A super-bright blue LED is used as a reference voltage source, which, simultaneously with performing 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 strongly, and VT1 also opens more strongly. which shunts the gate-source of the powerful field-effect transistor VT3.

As a result, the on-channel resistance of the field-effect transistor increases and the voltage across the load decreases. Trimmer resistor R5 can adjust the output voltage. Capacitor C2 is designed to suppress self-excitation of the stabilizer with an increase in the load current. Capacitors C1 and SZ - blocking for power supply 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 isolation voltage of the gate VT3. A gate-source voltage that is dangerous for VT3 may appear at the time of power-on or due to touching the terminals of this transistor.

Details... The KD243A diode can be replaced with any of the KD212, KD243 series. KD243, KD257, 1N4001..1N4007. Instead of transistors KT3102G, any similar with a small reverse current collector, for example, any of the series KT3102, KT6111, SS9014, BC547, 2SC1845. Instead of the KT3107G transistor, any of the KT3107, KT6112, SS9015, BC556, 2SA992 series is suitable. A powerful n-channel field-effect transistor of the IRLZ44 type in a TO-220 package, has a low gate-source opening threshold voltage, a maximum operating voltage of 60 V. The maximum direct current is up to 50 A, an 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 autonomous charger can be mounted on a small printed circuit board. As an autonomous power source, you can use, for example, four pieces of series-connected alkaline galvanic cells with a capacity of 4 A / H (RL14, RL20). This option is preferable if you plan to use this construction relatively infrequently.

If you plan to use this device relatively often or your player consumes much more current even when the display is off, then it will be advisable to use a rechargeable 6 V battery, for example, a sealed motorcycle or from a large hand lamp. You can also use a battery of 5 or 6 pieces of nickel-cadmium batteries connected in series. On a hike, on a fishing trip, to recharge batteries and power a pocket 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 the player is powered from this stabilized power source, it should be borne in mind that the regulating transistor is 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 the 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 at 3.2V.

The zener diode must have a stabilization voltage lower than the desired LED turn-on voltage. The microcircuit used a 74HC04. Setting up the display unit consists in selecting the threshold for switching on the LED using R2. The 74NC04 microcircuit makes it so that the LED lights up when discharged to a threshold that will be set by the trimmer. The current consumption by the device is 2 mA, and the LED itself will light up only at the moment of discharge, which is convenient. I found these 74NC04 on old motherboards, that's why I used it.

Printed circuit board:

To simplify the design, this discharge indicator may not be installed, because the SMD microcircuit can not be found. Therefore, the scarf is specially placed 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 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 analogs, but already with a radiator.

SMD resistors are installed for SAMSUNG devices (smartphones, tablets, etc., they have their own charging algorithm, and I do everything with a margin for the future) and they can not be installed at all. Do not put domestic KT3102 and KT3107 and their analogues, I had a voltage floating on these transistors due to h21. Take ВС547-ВС557, that's it. Scheme source: Butov A. Radioconstructor. 2009. Assembly and adjustment: Igoran .

Discuss the article MOBILE CHARGING FOR TELEPHONE

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

Comes in a standard bubble wrap bag.
The case is glossy, wrapped in a protective film.
Dimensions with fork 65x34x14mm








Charging immediately turned out to be inoperative - a good start ...
At the beginning I had to disassemble and repair the device in order to be able to test it.
It is very easy to understand - 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 not better


The board itself is mounted normally (for the Chinese), the soldering is good, the board is washed.






Real device diagram


What problems were found:
- Quite weak attachment of the plug to the body. The possibility of her remaining torn off in the outlet is not excluded.
- Lack of input fuse. Apparently the same wires to the plug are protection.
- Half-wave input rectifier - unnecessary savings on diodes.
- Small capacity of the input capacitor (2.2μF / 400V). For the operation of a half-wave rectifier, the capacity is clearly insufficient, which will lead to increased voltage ripple on it at a frequency of 50 Hz and to a decrease in its service life.
- Lack of input and output filters. Small loss for such a small and low-powered device.
- The simplest scheme converter on one weak transistor MJE13001.
- A simple 1nF / 1kV ceramic capacitor in an interference suppression circuit (shown separately in the photo). This is a gross violation of the security of the device. The capacitor must be of at least Y2 class.
- There is no damper circuit for damping backstop 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, overvoltage output.
- The overall power of the transformer clearly does not pull at 5W, and its very miniature size casts doubt on the presence of normal insulation between the windings.

Now testing.
Because the device is not initially safe, the connection was made through an additional mains fuse. If something happens - at least, it would not burn and leave without light.
I checked it without a case so that the temperature of the elements could be controlled.
No-load output voltage 5.25V
Power consumption without load less than 0.1W
Under a load of 0.3A or less, the charging works quite adequately, the voltage keeps normally at 5.25V, the ripple at the output is insignificant, the key transistor heats up within normal limits.
Under a load of 0.4A, the voltage begins to walk a little 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 walk in the range of 5.08V - 5.29V, the ripple at the output is 50Hz 85mV, the key transistor starts to overheat slowly (burns the finger), the transformer is warm.
Under a load of 0.50A, the voltage begins to walk strongly 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 wildly jumps 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 the load, the voltage drops sharply to indecent values.

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

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

For comparison, I will show you how the simplest Chinese charging 5V 2A from a tablet looks like inside, made in compliance with the minimum permissible safety standards.

Taking this opportunity, I would like to inform you that the lamp driver from the previous review has been successfully finalized, the article has been supplemented.

In short, my native charger for a Nokia phone with an otem, bitch, a millipad connector gave me a fuck:

Forever drifting away, falling out. Shit is shorter.

Fortunately, the phone has a microUSB connector, which has already become a standard. Well, mine, at least, has. Yes, and do not kick for Nokia, I have a phone for communication. For entertainment, a tablet. (like fucked). So, through this connector, the phone charges perfectly if there is a charge.

And here the other day they brought another, outdated, "original" Chinese charger for Nokia. They are demolished to me from time to time by employees. I don’t know the fuck, I don’t fix them to anyone, well, except for this case, and then for myself. Looks like because of the soldering iron on the table and a special reputation in our office. Well, not the point. She was with exactly that correct microUSB connector:

I'll say right away the simplest would be to re-solder the lace to the native charger, but I was not looking simple ways... For the experience gained, though small, is very useful. By the way, you can still buy a new charger, but these are costs, travel time. I sometimes forget, sometimes lazy.

I share my impressions, experiences, well, a little humor will not hurt.

I gave myself some coffee, so that I was flipping through Google for typical situations with charging, experienced advice, repair cases, not to fall asleep. It gave little sense, for there are thousands of them, if not billions, like the Chinese. Although it gave general idea circuitry of charging and understanding of a lousy, or completely fucked up.

I covered the table with a rough draft, took out several suitable corpses, plugged the soldering iron into the socket, and turned it around for troubleshooting:

Charging with the right lanyard went around the world solidly. Almost all semiconductor content has burned out:

The second of the bins, xs from which, without a lace, looked perky, but did not work:

For everyone, I also had a working power supply, xs from which, but with a fairly competent circuitry, just change the swollen condender:

But I felt sorry for him and put it aside. If it is impossible to fix that thread from the first two, I would take it.

On the way of low resistance, the troubleshooting of the second charge showed a burnt out diode and a resistor, which the cunning Chinese, due to the reduction in cost, use as fuses. I solder:

View from the other side. By the way, the circuitry is of a normal level, an order of magnitude better than the first charge:

It was decided to use the first one as a donor, the diode is normal, and the resistor is already burned out:

I found an analogue in the bins, which I paid a little later:

ATTENTION! AHTUNG! WORNING!

I sealed the diode and resistor, poked it into the socket, and the LED lit up cheerfully turned green:

There is a contact.

"The resistor is weak," said the charge, and the sad blue smoke confirmed her words.

Okay, I said, and crawled into the bins in search of an analogue. Along the way, finding a varistor and a choke, which narrow-eyed saved on. I re-solder:

New test, everything is ok (the photo did not work out very well).