Laptop power supply device. Alteration of BP from a laptop to adjustable. Best Exit - New Adapter
The purpose of the project is to build a universal adjustable power supply that can be used to charge nickel or lead batteries, not only automotive. The charger allows you to charge batteries with voltage from 4 to 30 V.
The first thing that will be needed to implement this project is the case. Suitable, for example, from the Chinese inverter 12-220 V. It is monolithic and made of aluminum.
You can take any other suitable size, for example, from a computer power supply unit.
The second is a power drop-down pulse power supply.
The voltage at the output of the unit used in this project is 19 V at a current of about 5 A.
This is a cheap universal laptop adapter. It is built on a PWM controller from the UC38 family, has stabilization and protection against short circuits.
The third is a digital or analog voltammermeter. The voltammermeter presented here was removed from the Chinese voltage stabilizer (30 V, 5 A).
The fourth is a bit of such electronic components as terminals and power cord.
The device is schematically shown on the following picture:
Now take a look at the power supply circuit. The TL431 microcircuit is located near Opro. It is this chip that sets the output voltage. In the strapping of only 2 resistors, and by their selection you can get the desired output voltage.
In this scheme, it is indicated as R13. In the existing block, its resistance is 20 com. Sequentially, this resistor needs to connect a variable to 10 kΩ, approximately as in the picture:
By rotating a variable resistor, it is necessary to achieve the output voltage in the region of 30 V. Then you need to turn off the "change" and measure its resistance at which the outlet voltage was 30 V, and replaced R13 to a resistor with a selected resistance. It turned out about 27 com. On this, the alteration of the adapter is completed.
To limit the current, the PWM adjustment method will be used, since the output current from the adapter from the laptop is very small.
In general, this scheme is a PWM voltage controller without a separate current limiting node. This rectangular pulse generator is based on the NE555 timer, which operates at a certain frequency. Diodes serve to constantly change the charge time and frequency condenser discharge. Due to this phenomenon, it is possible to change the diet of the output pulses. Since the power transistor operates in the key mode (it is either open, or closed), then you can observe a rather high efficiency. A variable resistor adjusts pulses.
Install the required charge current can be changed by voltage, that is, the rotation of a multi-turn variable resistor.
The transistor is suitable literally any. A N-channel field transistor with a voltage of 60 V and a current of 20 A.
Because of the key mode of operation, its heating will not be large, in contrast to linear circuits, but the heat sink does not prevent. In this project, an aluminum case is used as a heat sink.
The Shim Regulator Scheme is really simple, economical and reliable, but also needs a small refinement. The fact is that, according to the documentation, the NE555 chip has the maximum allowable supply voltage of 16 V. A at the output of the converted adapter, the voltage is almost 2 times higher, and when the timer is connected, the timer will definitely burn.
Solutions in this situation are several. Take a look at 3 of them:
- Use a linear stabilizer, let's say, from 5 to 12 V from the 78xx family or
build a simple stabilizer according to the following scheme:
The simplest solution will be the introduction of a linear stabilizer into the scheme, for example, 7805. But it should be remembered that the maximum supply voltage depending on the manufacturer varies from 24 to 35 V. In this project, the K7805 stabilizer is used with a maximum input voltage of 35 V data. If you fail to get such a chip, you can build a stabilizer of just three parts.
After assembly, you need to check the PWM regulator.
On the adapter board there are 2 active ingredients that are subjected to heating - the power transistor of the high-voltage circuit of the converter and the dual diode at the output of the circuit. They were squeezed and attached to the aluminum case. At the same time, they need to be isolated from the main body.
The facial panel is made of a piece of plastic.
In the adapter scheme there is a short circuit protection, but does not have protection against cords. But it is corrected.
Since during testing the output voltage of the adapter exceeded 30 V, the digital voltammeter burned down. Do not exceed the voltage to NE 1 V. will have to do without it. The charge current will be shown using a multimeter.
The charger turned out to be good - also charges without problems with the accumulators from the screwdriver.
Attached files:
How to make a simple turn bank with your own hands: Scheme of homemade Power Bank
Buying a laptop or a netbook, or rather counting the budget for this concentration, we do not take into account further related costs. Laptop himself should say $ 500, but another bag is $ 20, a mouse is $ 10. The battery when replacing (and its warranty resource is only a couple of years) pulls $ 100, and the power supply will cost the same amount, in the case of its combustion.
It is about him and the conversation here. One is not a very wealthy acquaintance, the power supply for a laptop Acer has recently stopped working. For the new one will have to give almost a hundred dollars, so it will be quite logical to try to fix it with your own hands. The BP itself is a traditional black plastic box with an electronic pulsed converter inside, providing a voltage of 19V at a current 3a. This is the standard for most laptops and the only difference between them - the power plug :). Immediately give here several power supplies schemes - click to enlarge.
When the power supply is turned on to the network, nothing happens - the LED does not shine and the voltmeter shows zero. Verification of a network cord did not give anything. We disassemble the housing. Although it is easier to say than to do: screws or screws are not provided here, so we will break! To do this, you will need to put the knife and knock on it slightly hammer. See do not cease, but then destroy the fee!
After the housing is slightly disperse, insert a flat screwdriver into the resulting slot and carry out the contour of the compound of the body halves, carefully flushing it on the seam.
Disagreeing the body check the fee and parts on the subject of something black and charred.
The transversion of the input circuits of the network voltage 220V bulk revealed a malfunction - this is a self-healing fuse, which for some reason did not want to recover when overloading :)
We replace it with a similar one, either on a simple fusible with a current of 3 amps and check the work of BP. The green LED lit up, testifying to the presence of a voltage of 19V, but there is still nothing on the connector. More precisely, sometimes something accesses, as when the wire is inflection.
We have to repair and connect the power supply cord to the laptop. Most often, the cliff occurs at the injection site into the case or on the power connector.
Cut the first at the body - not lucky. Now near the plug, which is inserted into the laptop - there is no contact again!
Weight case - a break somewhere in the middle. The easiest option, cut the cord in half and leave the workshop, and knock out the non-working. So did.
Shipping back connectors and test. Everything has earned - the repair is completed.
It remains only to glue the halves of the housing by glue "moment" and give the power supply. All repair of BP took no more than an hour.
The power supply is a device that serves to convert (decrease or enhancing) AC voltage to a given constant voltage. Power supplies are divided into: transformer and impulse. Only transformer structures of power supplies were originally created. They consisted of a power transformer feeding from the household network 220V, 50Hz and a rectifier with a filter, a voltage stabilizer. Due to the transformer, the network voltage is reduced to the necessary values, followed by the straightening of the voltage by the rectifier consisting of diodes included in the bridge circuit. After straightening, the constant pulsating voltage is smoothed parallel to the connected capacitor. If you need to accurate stabilization of the voltage level, voltage stabilizers are used on transistors.
The main drawback of the transformer power supply is a transformer. Why is that? All because of weight and dimensions, as they limit the compactness of the power supply, while their price is high enough. But these power supplies are easy to design and this is their dignity. But still in most modern devices, the use of transformer power supplies has become not relevant. I replaced the pulsed power supplies.
The composition of the pulse power supplies includes:
1) Network filter, (input choke, electromechanical filter, providing interference detuning, network fuse);
2) rectifier and smoothing filter (diode bridge, cumulative condenser);
3) inverter (power transistor);
4) power transformer;
5) the output rectifier (rectifier diodes included in the semi-liter scheme);
6) output filter (filtering capacitors, power chokes);
7) inverter control unit (PWM controller with strapping)
The pulse power supply provides stabilized voltage due to the use of feedback. It works as follows. The network voltage enters the rectifier and smoothing filter, where the voltage of the network is straightened, and the pulsation is smoothed through the use of capacitors. At the same time, the amplitude of about 300 volts is withstanding. The next step is connected inverter. His task is the formation of rectangular high-frequency signals for the transformer. Feedback with the inverter is carried out through the control unit. From the output of the transformer, high-frequency pulses arrive at the output rectifier. Due to the fact that the frequency of the pulses is about 100 kHz, then it is necessary to use high-speed semiconductor SCotke diodes. At the final phase, the voltage is smoothed on the filter capacitor and choke. And only after that, the voltage of a given value is fed to the load. All, enough theory, let's go to practice and start making a power supply.
Power supply housing
Each radio amateur that is engaged in electronics, wanting to arrange its devices often faces a problem where to take the case. This problem has suffered me, which in turn came across the thought, and why not make the body with their own hands. And here my searches began ... Search for a ready-made solution How to make the case did not lead to anything. But I did not despair. Thinking for a while, I had a thought, and why not make a plastic box for laying wires. In size, he approached me, and I began to cut and glue. Watch the pictures below.
The sizes of the box were selected based on the size of the power supply board. We look at the drawing below.
Also in the case there must be more indicator, wires, controller and network connector. We look at the drawing below.
To install above the listed elements in the case, the necessary holes were cut. We look at the drawings above. Well, finally, to give the body of the power supply of aesthetics, it was painted in black. Watch the pictures below.
Measuring device
I will not say that it was not necessary to search for a measuring device for a long time, the choice immediately fell on the combined digital voltammermeter TK1382. Watch the pictures below.
The measurement ranges of the device are for the voltage of 0-100 V and the current to 10 A. The device also installed two calibration resistors for adjusting voltage and current. We look at the drawing below.
As for the connection scheme, it has nuances. Watch the pictures below.
Power unit circuit
To measure the current and voltage, we use the scheme - 2, see the drawing above. And so in order. On the available power supply from my laptop, we first find the electrical principal scheme. The search must be carried out on the PWM controller. This CR6842S is CR6842S. We look at the scheme below.
Now let's touch the alterations. Since the adjustable power supply will be made, then the scheme will have to remake. To do this, make changes to the scheme, these sites are circled with orange. We look at the drawing below.
Scheme section 1.2 provides power to the PWM controller. And it is a parametric stabilizer. The voltage of the stabilizer is 17.1 V is selected due to the features of the work of the PWM controller. At the same time, for powering the PWM controller, we set the current through the stabilizer of about 6 mA. "The peculiarity of this controller is that in order to turn it on, the supply voltage is needed more than 16.4 V, 4 mA consumption current excerpt from Datasheet. With such a reworking of the power supply, it is necessary to abandon the winding of self-care, since its use is not advisable at low outlet voltages. In the picture below, you can see this node after rework.
The section of the circuit 3 provides voltage control, under the data of the elements of the elements, the regulation is carried out in the range of 4.5-24.5 V. For such a rework, it is necessary to drop resistors marked in the figure below orange, and their place to spare a variable resistor to adjust the voltage.
On this alteration is completed. And you can trigger. IMPORTANT!!! Due to the fact that the power supply is powered by a 220 network to be careful, to avoid contact with the network voltage! It is dangerous for life !!! Before the first launch of the power supply, you must check the correct installation of all the elements, and then turn on the 220 V network, through the incandescent light bulb 220 V, 40 W in order to avoid failure of the power elements of the power supply. You can see the first launch in the figure below.
Also, after the first launch, check the upper and lower limits of voltage control. And as thought, they lie at the given limits of 4.5-24.5 V. Watch the drawings below.
And finally, when testing with a load on 2.5, the body began to warm well, which was not suitable and I decided to make perforation in the cooling case. Place for perforation chose based on the place of the greatest heating. For perforation of the housing, I made 9 holes with a diameter of 3 mm. We look at the drawing below.
To prevent accidental entry into the housing of the conductive elements, a safety damper is glued on the reverse side of the cover. We look at the drawing below.
Brought to repair the ADP-90YD power supply from the ASUS laptop. That charges the laptop, then no. You will endure out of the outlet, insert it seems fine, maybe something leaves.
I turn on the network, I check the tester 19.35 in there, the wires moved to fall smoothly, as if the container was discharged, well, yes, it may be departed. You need to open the power supply. Inserted the knife into the joint of the 2 halves of the case, neatly knocked the hammer on the knife, the case and opened.
Place in three layers of screens. Everything disappeared, removed. The power supply is dense, there is also a lot of sealant nitally.
When a quick inspection, a torn leg of the filtering choke was discovered along the input chain of 220 V. "So it caused such a strange voltage drop," I thought. Restored the throttle, check - the result is the same. When turned on 19.35 V, after 1 second it starts to fall smoothly to zero. Apparently from my slobs with a hammer on the BP housing, choke and fell off. But that's what I noticed if you turn off the power supply from the 220 V network, after a few seconds, 19.35 V and even the charge light lights up on the laptop, but then the network container is completely discharged and the power supply off. Very strange, apparently, some kind of protection is triggered and the power supply does not work, but what is the reason ...?
Collected out of 5 watt resistors a small load, the consumption current was only 0.07 and the power supply was standardly started. In general, it is not clear ..., and the current consumption of a laptop does not mean enough? I did not want, but you have to climb on the Internet, remove the whole sealant to check everything.
Shem controller was performed, there was clearly the protection was clear, but the protection turned off when the network container began to be discharged, but I didn't even jerkly check the voltage on it.
Search the Internet issued the following:
check the voltage on the network electrolyte if it is greater than 450 V ( and where is there so much?), urgently change 2 film capacitor 474 NF 450 V and you will be happy
Red Capacity for Replacement 
Voltage on network height.
So there is, the voltage on the 496 V network capacity, everything fell into place. Such a stress at idle is very high, PWM controller sees it and goes into protection, and if you turn off the power voltage, the container smoothly discharged, reaching normal values \u200b\u200band the power supply is briefly started. Here, from where they appeared 19 in if you turn off 220 V. And when I started the BP at least under a small but load, the voltage did not jump so much and the PWM did not go into defense.
It was possible to finish on this, replace the film containers with which it turned out to be serious problems.
From the first left 15% of the container. 
The second saved 68% of the tank.
But it became interesting, where almost 500 in the hot side of the power supply and, and there are two of these tanks. The Internet helped again, to decoke the entire BP in search of the answer did not want. The information was found on the forum, everything explained the phrase:
It stands there passive capacity corrector. At the failure of metal-making capacitors in the circuit of the corrector, and the proofreader goes to the spread, the voltage to the network bank is above 500 volts. Therefore, if you only replaced the network bank, it will not work for a long time. It is necessary to bring the tension of the corrector to normal or exclude it at all.
It remains to buy and replace the tanks, but here it is also not so simple.
The Chinese containers with such a face value and dimensions were, but we do not have. There were only 400 or 600 V. more - no less, but the left tank is just 474 NF 600 V, and how to shove it instead of those in the middle. There are so many places there, and 400 V was no less than the size. Moreover, the sellers assured that such small dimensions, the Chinese hardly managed to shove the qualitative to do, precisely why they failed. I had to choose in size. The right tank successfully approached the dimensions, but there was 330 NF 400 V, I had to put them.
