In order to charge any portable device, such as a phone or tablet, from the 12-volt on-board network of a car, you will have to use a DC-DC converter. But buying an inverter is not necessary when you can independently assemble, for example, a very simple design based on the 34063api chip.
The chip is specially designed for this purpose and many charger manufacturers use it as the main driver in car chargers. It was this microcircuit that became the basis for most of the "charges" powered by the cigarette lighter.
The microcircuit has a built-in output stage that delivers current up to 3A to the load. Thanks to this, it can be considered universal - it can charge almost any mobile device, including devices with high-capacity batteries, such as tablet computers.
The microcircuit gives a stable output voltage of 5 volts. It is optimal for recharging the batteries of a variety of portable devices. The choke consists of 20 turns of 0.6 mm thick wire wound on a dumbbell. Drops and surges of on-board voltage for the microcircuit are not terrible, since the input voltage range is from 7 to 40 Volts.
The microcircuit works stably even with sudden temperature changes and weather changes, without overheating in the process. You can connect 34063api in several ways. Here is the most reliable option, which is also simple and easy to reproduce.
A particularly valuable quality of this microcircuit is that it is possible to simultaneously connect several mobile phones to the output. At the same time, the quality of charging, even if all models are different, will be no worse than through a standard device. You can also exclude input and output capacitors from the circuit, which are needed only to filter noise.
Sometimes it becomes necessary to charge a mobile phone from the car's on-board network. To do this, you can buy special chargers (cost $ 3-5), but it is much more interesting to make such a charger with your own hands.
The proposed design of a car charger for a mobile phone is quite simple and contains only a couple of components.
The required voltage is provided by the domestic low-power zener diode of the KS156A series.
The zener diode can be replaced with a similar one. In this circuit, it does not heat up at all, so that zener diodes of any power can be used. Often radio amateurs have questions with the marking of the zener diode. The specified zener diode has three different types of markings, but most often it is marked with an orange stripe on the cathode side and a white stripe on the anode side, it is usually found in a glass case, but it happens that more powerful ones come across - already in a metal version.
A powerful domestic transistor of the KT819 type (with any letter) was used as a power switch. Just in case, it is advisable to install a transistor on a heat sink, although heat dissipation is not too terrible when charging a mobile phone. The transistor can be replaced by - KT805, 817, 815 or powerful field keys. When replacing field-effect transistors of the IRFZ44, IRFZ48, IRF3205 series and similar in power, there is no need for a heat sink in this case.
I used a resistor with a power of 2 watts, but during operation it almost does not heat up, so you can get by with a resistor with a power of 0.5-1 watts.
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A mobile phone is our true friend in any situation, but it does not work forever, there comes a time when it needs to be recharged. Network chargers provide an output voltage of 5-6.5 volts at a current of up to 500mA to charge the built-in battery of a mobile phone. The question arises - is it possible to obtain exactly such parameters in a car? It is possible and even very simple!
Of course, similar charges can be purchased at the store, but the easiest way is to do it yourself, while the circuit consists of only one component - a linear stabilizer on a 7805 chip.
The cost of such a microcircuit does not exceed $ 1, in return, a ready-made charger is sold in stores for $ 4-8.
First you need to purchase a stabilizer chip. In appearance, the microcircuit looks like a transistor. We determine the pinout very simply. We hold the microcircuit with the inscription towards us. The middle terminal is common, it is connected to the minus of the car battery, the left output is the input - it is connected to the plus of the battery. We take a reduced voltage of 5 volts from the minus and the right output.
Despite the fact that this is a linear voltage regulator, the microcircuit is quite powerful, but nevertheless it needs to be cooled. You can use an aluminum heat sink as cooling, or directly screw the microcircuit to the case (if the latter is metal) in which you plan to mount this charger.
Well, we have put together a simple but good enough charger for all types of mobile phones, you just need to find a plug for your mobile phone and good luck!
The microcircuit itself is a linear voltage stabilizer and you should not connect large loads of 1.5 Amperes to it, although the maximum load current is 2 Amperes.
Hello Habra gentlemen and Habra ladies!
I think some of you are familiar with the situation:
“Car, traffic jam, N-th hour of driving. The communicator with the navigator running for the 3rd time beeps about the end of the charge, despite the fact that it is connected to charging all the time. And you, as an evil, are absolutely not oriented in this part of the city.
Next, I will talk about how, with moderately straight hands, a small set of tools and a little money, build a universal (suitable for charging with a rated current, both Apple and all other devices), USB car charging for your gadgets.
WARNING: There are a lot of photos under the cut, some work, no LUT and no happy ending (not yet).
Author, what for all this?
Some time ago, the story described in the prologue happened to me, the Chinese usb twin, absolutely shamelessly let my smart phone run out during navigation, out of the declared 500mA it gave out about 350 for both sockets. I must say I was very angry. Well, okay - I'm a fool myself, I decided, and on the same day, in the evening, a 2A car charger was ordered on eBay, which rested in the depths of the Chinese-Israeli mail. By a lucky chance, I had a DC-DC step down converter with an output current of up to 3 A lying around, and I decided to assemble a reliable and universal car charger 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 little charging trick.
2. Ordinary - focused on most gadgets, for which shorted DATA + and DATA- are enough to consume the rated charge current (the one that is declared on the charger of your gadget).
3. Stupid - in which DATA + and DATA- hang 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 charge rate or even in the absence of it under load.
4. Cunning%!$&e - since they have a microcontroller installed inside, which tells the device that something from the category of what the notorious Kipling hero told animals - “We are of the same blood, you and me”, checks the originality of the charge. For all other devices, they are the third type of memory.
The last two options, for obvious reasons, I consider not interesting and even harmful, so we will focus on the first two. Since our charging should 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 rest. I will only note that if you mistakenly connect the gadget to a USB socket not intended for it, nothing terrible will happen, it will simply take the same notorious 500mA.
So, the goal: "After working a little with your hands, get a universal charger for the car."
What do we need
1. To begin with, let's deal with the charge current, usually it is 1A for smartphones and about 2 Amperes for tablets (by the way, my Nexus 7, for some reason, does not take more than 1.2A from its own charge). In total, for the simultaneous charging of an average tablet and smartphone, we need a current of 3A. So the DC-DC converter that I have available is quite suitable. I must admit that a 4A or 5A converter would be better suited for these purposes, in order to have enough current for 2 tablets, but I did not find compact and inexpensive solutions, and even time was running out.So I used what 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 that I soldered from an old USB hub.
You can also use regular sockets from a USB extension cable.
3. Breadboard. 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 a nominal value of 50 kOhm and one at 70 Ohm. On the first 4, the Apple charging circuit is being built, I used 70 Ohms to limit the current on the LED.
5. Body. 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 shorted the DATA + and DATA- pins to each other on one of the sockets:
* I apologize for the harshness, I got up early and the body wanted to sleep, and the brain continued the experiment.
This will be our outlet for non-apple gadgets.
2. We cut off the size of the breadboard we need and mark and drill holes in it for the mounting legs of the USB socket, at the same time checking that the contact legs match the holes in the board.
3. We 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).
The photo is for clarification only, the contacts are already soldered on the breadboard
4. Solder the following circuit to 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 USB power circuit, in parallel to + 5V and GND I soldered yellow ice with a 70 Ohm resistor to limit the current.
A convincing request to people with a fine mental organization and other lovers of beauty: "Do not look at the following picture, because the soldering is crooked."
I am brave!
5. We fix the converter board on our breadboard. I did this with the help of legs from all 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 polarity!
7. We take the case, mark and drill holes for mounting our board, mark and cut out a place for a USB socket and add holes for ventilation opposite the converter chip.
We fasten the breadboard with bolts to the case and get this box:
In Machine it looks like this:
Tests
Next, I decided to check whether my devices will really consider that they are being charged from their native charger. And at the same time measure the currents.Power is provided by the PSU from an old 24V 3.3A printer.
I measured the current before going to USB.
Looking ahead, I’ll say that all the devices I have recognized 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 charge 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 network (I only charged one device at a time).
In order for both Android devices to take the maximum from charging, I had to solder a small adapter (which connected to apple USB), HTC Sensation is connected to it.
I connected to USB socket number two: Ipod Nano, Ipod Touch 4G, Iphone 4S, Ipad 2. Since Nano is ridiculous to charge with such a thing - it took a maximum of 200 mA from me, checked Touch 4g and iPad. Ipod charged 1 hour 17 minutes from zero to 100% (albeit with IPAD 2). iPad 2 took 4 hours and 46 minutes to charge (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 data 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 charging with the maximum allowable current for your device and gradually reduces the current. The charge level is determined by the 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 point why this topic is called: "Attempt number one." The fact is that the maximum that I managed to squeeze out of the charge is: 1.77A
Well, the reason, in my opinion, is not the optimally selected inductor, which in turn prevents the Buck-converter from delivering its maximum current. I thought to replace it, but I don’t have a tool for soldering SMD and it’s not expected in the near future. This is not a fault of the ebay board designers, this is just a feature of this circuit as it caters for 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 a car in reasonable time.
In connection with the foregoing, it was decided to leave this charge as it is and assemble a new one, completely with your own hands, based on a more powerful LM2678 converter,
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 CC from more experienced comrades - on the contrary, they are welcome in the comments.
3. I apologize for possible technical inaccuracies, because Until recently, I did not deal with electronics and circuitry.
Thank you for your attention, good luck and inexhaustible optimism!
Modern mobile devices have become an indispensable part of our lives. First of all, we are talking about phones and tablets. We use them everywhere, at home, on the street, in the car. In the car, navigators, video recorders, etc. are added to them. And what is needed for the normal operation of these devices? Of course, food, because any, even a very good battery, will “sit down”, in the end.
You can buy a ready-made USB charger for everything that we use in the car. But there may be problems with the number of sockets, with power, etc. As a rule, the power of the charger is limited to a current of 0.5 A, although many say 1 A, but they are not able to withstand such a current.
As for my particular case, this charger, which is essentially a voltage stabilizer on the 7805 chip, was used in order to hide it under the dashboard. As a result, having powered it from the cigarette lighter and hidden it under the instrument panel, only mini USB plugs were brought out to the instrument panel, for the navigator and the DVR. This made it possible to provide power to gadgets, while leaving the cigarette lighter sockets unoccupied. And perhaps the most important thing is to get rid of the wires that got in the way at hand and from their non-aesthetic appearance.
So, in our article we will talk about an alternative, about self-manufacturing a USB charger for a car based on a 7805 stabilizer chip.
How to make a 1.5 Amp USB charger in a car with your own hands (Option 1)
The voltage regulator of the L7805 series (current 1 A) or its analogue L7805CV (current 1.5 A) will be used as the "heart" of our charger. In fact, there can be a great variety of analogues used. In principle, the entire 7805 series of microcircuits will be suitable for this. We will talk about analogues in more detail a little later.
The electrical circuit for connecting the stabilizer itself is simple, it is similar to the power stabilizer, which we talked about in our other article “ 12 volt power stabilizer in a car». We can say that these are fellow microcircuits, only their stabilization voltages are different.
You can assemble everything both by surface mounting and on the board. It is possible on the usual simple universal circuit board. In order for the microcircuit to be able to develop its maximum supply current, it must be placed on a radiator. In our case, the radiator is taken from a computer processor.
The microcircuits themselves - stabilizers can be produced in various cases. Possible housing options and applied analogs are shown in the figure below.
In our assembly, the TO-220 case is used ... It is also possible to use microcircuits with the KIA 7805 index. You can see a more detailed Data sheet for these microcircuits.
Connecting the mini and micro USB plug from the charger in the car
After you have assembled the USB device, you need to correctly connect the USB connectors. You can take a wire with an already factory mini, micro USB plug, or you can buy an "empty" plug in the store and solder the wire to it. The correct connection of various types of USB is shown in the figure below.
In my case, a mini USB plug was needed, which was soldered to the wire. The view is shown without the body.
Then, using a universal device, the voltage was checked again so as not to spoil electronic gadgets. And then the battery of the audio player was already charged.
Subsequently, the charger was installed under the instrument panel, and mini USB plugs were brought out: one on the instrument panel for the navigator, the second under the roof for the DVR.
I apologize for the view in the garage.
Charger in the car for 5 volts for a smartphone, navigator, video recorder, tablet, built on the principle of PWM modulation (USB) at 4 Amperes (Option 2)
However, the epic with the charger did not end there. Again, due to a banal reason, when there is not enough output power for consumers, the supply current, which is essentially the same, provided that the on-board network voltage in the car is constant, since these values will be directly proportional.
So, during the long-term joint operation of the navigator and the DVR, one microcircuit was not able to “pull out” the power of these two devices, even with the radiator installed. As a result, it overheated and briefly turned off. At the same time, the navigator "cursed" at the power off.
There seem to be two solutions to the problem. The first is to “fence the garden” and make parallel circuits, each of which will be “hung” with its own consumers. Let's say one DVR, the second navigator. In fact, in the photo above, where two microcircuits are mounted on one radiator, this is done. However, it’s good if everything is limited to this, and if you need to connect a smartphone, tablet, or something else ... Here you can’t do without more serious currents, and therefore without alternative options. Such an alternative would be to use a micro-assembly with PWM modulation. I will not explain in detail what it is, but the principle of all this is based on the fact that the current is not constantly supplied to the load, but at a very high frequency. As a result, it becomes possible to reduce the heating of the microcircuit, due to the very periods when it “rests”, and the load at such a high frequency perceives the power as constant, although it is not so ...
So, such a scheme does not require large radiators to remove heat, while rather high currents will be provided. In general, everything will be as we need it. About this option below. To reduce the voltage, a microcircuit, an inductor and elements for strapping were used. The microassembly has the designation KIS3R33S,
Its installation can be performed according to the diagram from the Datasheet. However, by default, with such a strapping, it has an output voltage of 3.3 volts, but we need 5 volts for USB.
In this case, it will be necessary to select resistors R1, R2. A table with recommended resistor values that affect the supply voltage is also taken from the Datasheet. This feature of changing the voltage by selecting resistors makes this device a universal assistant, if necessary, to power the load not only with a voltage of 5 volts as for USB.
It should be noted that this device confidently holds a load with a current consumption of 3A, and peak performance can reach 4A. If you are too lazy to assemble such a device, there is no time or you cannot do it, then you can purchase such an assembly for a price of about $ 2 at well-known sites, online stores.
I must say that such a Chinese voltage converter KIS-3R33S (MP2307) is quite good for its price, while it is capable of delivering high currents, as we already know, up to 4A. This means that such an assembly can replace a KRENOK pair or a 7805 series, which we talked about in the first part of the article. At the same time, it will be more compact and with higher efficiency.
So, I bought this set. Then I also bought a junction box, which is used for wiring in apartments. This became the body of the converter - the charger.
An LED was also attached in order to control whether voltage is applied to this "box". You can read about connecting an LED to 12 volts in a car in the article "How to connect an LED to 12 volts". Then everything was installed under the instrument panel, behind the glove box.
Connected to cigarette lighter. The voltage on it appears only when the "ignition" is on, which is very fortunate for me.
Wires are also forwarded to gadgets.
Now the charger current has increased to 4 amps, which is quite enough for now.
A feature of this charger is that it can work both in cars, where the voltage of the on-board network is 12 volts, and in trucks, where it is 24 volts. At the same time, the charger does not need any alteration and adjustment.
