How to repair a LED flashlight? Diagram of a Chinese flashlight with mains charging

Repair of LED lights - an overview of breakdowns, device and diagram

For the normal life of a person in the dark, he always needed light. With the advancement of technology, light sources have improved, starting their way from torch fire and kerosene lamps, ending with rechargeable flashlights. A real revolution in the world of lighting technology was the creation of the LED, which immediately entered everyday life.

Modern LED lights are very economical, the light travels very far and is very bright. A huge share of such lithium lanterns in the modern market - made in China, they are very cheap and affordable. It is because of the low cost that breakdowns of various kinds often occur. In this article, we will consider the main problems of repairing LED lights and how to fix them yourself.

How does an LED flashlight work?

The classic device of flashlights is very simple (regardless of the type of housing, be it the Cosmos model or DiK AN-005). An LED is connected to the battery, the circuit is broken by the shutdown button. Depending on the number of LEDs, the number of light elements themselves (for example, the main lamp on the front and the auxiliary lamp in the handle), a stronger battery (or several), a transformer, resistance are added to the circuit, and a more functional switch is installed (Fo-DiK flashlights) ...

Why does the flashlight break?

Now we will omit the problems associated with the improper operation of a Chinese flashlight - "I dropped it into a bowl of water, turned it on and off, but for some reason it does not shine." Flashlights are cheap by simplifying the electrical circuits inside the device. This allows you to save on components (on their quantity and quality). This is done so that people often buy new ones, and the old ones are simply thrown away, without even trying to fix them with their own hands.

Another point of economy is people working in production who are not qualified enough to do this kind of work. As a result, there are many small and large errors in the circuit itself, poor-quality soldering and assembly of components, which leads to constant repair of lamps. In most cases, all problems can be solved by correctly diagnosing them, and we will deal with this further.

The cause of the lamp breakage

Most likely, when switching the switch, the LEDs do not want to light up due to a malfunction in electrical circuit... The most common ones are:

• oxidation of battery or battery contacts;
• oxidation on the contacts to which the battery is connected;
• damage to the wires going both from the battery to the LED and vice versa;
• defective item shutdown;
• lack of power in the circuit;
• breakage in the LEDs themselves.

Oxidation. Most often it occurs in already old lanterns, which are often used in various weather conditions. Plaque that appears on the metal interferes with normal contact, due to which the flashlight on the batteries may flicker or not turn on at all. If oxidation is observed on a battery or accumulator, then you need to think about replacing.

How do I fix contacts? Light dirt is removed with your own hands with a cotton swab dipped in ethyl alcohol. When the contamination is very serious, even rust has gone along the body, the use of such a battery can be dangerous to health and life. In stores, you can now find a sufficient number of new batteries and accumulators, even for old types of flashlights.

Take care of the environment - don't throw old batteries in the trash bin, you probably have collection points in the city for recycling.

Oxidation also forms on the contacts in the lamp itself. Here, too, you need to pay attention to their integrity. If the contamination can still be removed with a cotton swab and alcohol, stop at this option. For hard-to-reach places, you can use a cotton swab.

If the contacts are completely rusted or even rotted (which is not uncommon for an old flashlight), they will have to be changed. Ask an electronics store if there are similar contact elements (for at least ten years, they are absolutely identical in all flashlights, with rare exceptions). If there are no similar ones, choose the most similar option. Armed with a thin soldering iron, they can be easily re-soldered.

Damage to the wire contacts. In addition to the above-described places, contacts are present in the places where the wires of the electrical circuit are soldered. Cheap manufacturing, rush to assemble and negligent workers often lead to forgetting to solder some wires altogether, so the LED flashlight doesn't work even if it's just out of the box. How do I repair my flashlight in this case? Carefully view the entire circuit by gently pushing back the wires with medical tweezers or other thin object. If a failed soldering is found, it must be restored using the same thin soldering iron.

The same can be done with flimsy joints, the characteristic state of which is a torn, bare vein, barely attached to the place of adhesion. If you have enough time and resources, and you value this flashlight, you can methodically and efficiently solder all contacts in general. This will significantly increase the efficiency of such a circuit, protect exposed elements from moisture and dust (which is important if the flashlight is a headlamp), and in subsequent cases of repairing the flashlight, this item will be eliminated. Repair of small LED headlamps is carried out in exactly the same way, the dimensions are simply different.

Damaged wires. After you have made sure that the contacts are clean, you can start looking at all the wires in the circuit for damage or short circuits. It is common for wiring to be damaged by an improperly installed housing cover, either during factory assembly or after a previous repair. The wire got caught between two body parts and was cut or crushed while tightening the bolts. During the flow of current electrical circuit could overheat or even short-circuit, this will inevitably lead to the repair of the LED flashlight.

All broken sections must be soldered together to provide better conductivity than simple twisting. Do not forget to insulate all exposed areas, it is best to use a thin heat shrinkage. Heavily damaged wires, which could already be rusty, it is advisable to completely replace them with your own hands (select the appropriate core). After such a revision, old lanterns can shine much brighter - the modernization performed improves the current flow.

Defective switch. Also pay attention to the contacts of the wires with the switch terminals, troubleshoot. The easiest way to find out if your flashlight is not working because of a switch is to close the circuit without it. Exclude it from the circuit by directly connecting the battery-LEDs (you can also try from the mains with the corresponding battery voltage). If they light up, we change the switch. Perhaps it has already broken down mechanically from reusable use, the flashlight just turns off, and a defect in production is also possible. If the LEDs do not want to light up directly from the battery, follow on.

Lack of current in the network. The most common cause of such a malfunction is discharged or very old lithium battery... The LED flashlight can glow when charging, but if you unplug it from the outlet, it immediately goes out. A complete malfunction is observed when the flashlight does not charge at all and does not react in any way to switching on, although the charging indicator is on stably.

Breakage of LEDs. When all the problems with the wires are eliminated (or they were not), pay attention to the LEDs themselves. Carefully take out the board on which they are soldered. Use a multimeter to find out the current that goes in and out of the board. If possible, check the contacts on the entire board. Most likely, the LEDs are connected in series, so if one breaks down, the rest will not shine either. Checking each one, if there are 3 or more of them, is a rather long process, so it is better to immediately buy new LEDs.

LED board

Conclusion

Many cheap Chinese LED flashlights, assembled under austerity conditions, are the most prone to electrical breakdowns. Wires with a very small cross-section are installed there, which are quite problematic to solder even with a good device. However, almost all problems with wires and batteries can be easily eliminated at home, with the right and careful approach, even an inexpensive refurbished flashlight will serve you more than three years of constant use.

lampagid.ru

How to fix your LED Chinese pocket flashlight yourself. DIY LED lights repair instructions with visual photos and videos

Today we are going to talk about how to fix an LED Chinese pocket flashlight by yourself. We will also consider instructions for repairing LED lights with our own hands with visual photos and videos

As you can see, the scheme is simple. The main elements: a current-limiting capacitor, a rectifier diode bridge on four diodes, a battery, a switch, super-bright LEDs, a flashlight battery charging indication LED.

Well, now, in order, about the purpose of all the elements in the flashlight.

Current limiting capacitor. It is designed to limit the charging current of the battery. Its capacity may vary for each type of flashlight. A non-polar mica capacitor is used. The operating voltage must be at least 250 volts. In the circuit, it must be shunted, as shown, with a resistor. It serves to discharge the capacitor after you unplug the flashlight from the charger. Otherwise, you could get an electric shock if you accidentally touch the 220 volt mains terminals of the flashlight. The resistance of this resistor must be at least 500 kOhm.

The rectifier bridge is assembled on silicon diodes with a reverse voltage of at least 300 volts.

A simple red or green LED is used to indicate that the flashlight battery is charging. It is connected in parallel with one of the rectifier bridge diodes. True, in the diagram, I forgot to indicate the resistor connected in series with this LED.

It makes no sense to talk about the rest of the elements, so everything should be clear anyway.

I would like to draw your attention to the main points of repairing an LED flashlight. Consider the main malfunctions and how to fix them.

1. The flashlight stopped shining. There are not so many options here. The reason may be the failure of super-bright LEDs. This can happen, for example, in the following case. You put the flashlight on charge and accidentally turned on the switch. In this case, a sharp current surge will occur and one or more diodes of the rectifier bridge may be punctured. And behind them, the capacitor may not be able to withstand it and will close. The battery voltage will rise sharply and the LEDs will fail. So, in any case, do not turn on the flashlight when charging, if you do not want to throw it away.

2. The flashlight does not turn on. Well, here you need to check the switch.

3. The flashlight runs out of power very quickly. If your flashlight is "experienced", then most likely the battery has worked out its service life. If you actively use the flashlight, then after one year of operation, the battery no longer holds.

Problem 1. LED flashlight does not turn on or flickers during operation

This is usually the reason for poor contact. The easiest treatment is to tighten all threads tightly. If the flashlight does not work at all, start by checking the battery. Perhaps it is discharged or out of order.

Unscrew the back cover of the lamp and use a screwdriver to close the housing to the negative contact of the battery. If the flashlight lights up, then the problem is in the module with the button.

90% of the buttons of all LED lights are made according to the same scheme: The button body is made of aluminum with a thread, a rubber cap is inserted there, then the button module itself and a pressure ring for contact with the body.

The problem is most often solved in a loosely clamped pressure ring. To eliminate this malfunction, it is enough to find round-nose pliers with thin stings or thin scissors that need to be inserted into the holes, as in the photo, and turned clockwise.

If the ring moves, then the problem has been fixed. If the ring is in place, then the problem lies in the contact of the button module with the body. Unscrew the retaining ring counterclockwise and pull the button module outward. Often poor contact occurs due to oxidation of the aluminum surface of the ring or the rim on the PCB. Indicated by arrows)

It is enough just to wipe these surfaces with alcohol and the functionality will be restored.

Button modules are different. Some of whom contact goes through printed circuit board, others, in which the contact goes through the side lobes to the body of the lantern. Just bend such a lobe to the side to make the contact more tight. Alternatively, you can solder tin, so that the surface is thicker and the contact is pressed better. All LED lights, in principle, are arranged the same

The plus goes through the positive contact of the battery to the center of the LED module, while the minus goes through the case and is closed with a button.

It will not be superfluous to check the tightness of the LED module inside the case. This is also a common problem with LED lights.

Using round nose pliers or pliers, turn the module clockwise until it stops. Be careful, it is easy to damage the LED at this point.

These actions should be enough to restore the functionality of the LED flashlight.

It is worse when the flashlight works and the modes are switched, but the beam is very dim, or the flashlight does not work at all and there is a burning smell inside.

Problem 2. The flashlight works fine, but dimly, or does not work at all and there is a burning smell inside

Most likely the driver is out of order. The driver is electronic circuit on transistors, which controls the flashlight modes and is also responsible for a constant voltage level, regardless of the battery discharge.

You need to unsolder the burned-out driver and solder a new driver, or connect the LED directly to the battery. In this case, you lose all modes and remain only with the maximum.

Sometimes (much less often) the LED fails. It can be checked very easily. bring a voltage of 4.2 V / to the contact pads of the LED. The main thing is not to mix up the polarity. If the LED is on brightly, then the driver is out of order, if on the contrary, then you need to order a new LED.

Unscrew the module with the LED from the case. There are different modules, but as a rule, they are made of copper or brass and

The weakest point of such lights is the button. Its contacts are oxidized, as a result of which the flashlight begins to shine dimly, and then it may stop turning on altogether. The first sign is that the flashlight with a normal battery shines weakly, but if you click the button several times, the brightness increases.

The easiest way to make such a lantern shine is to do the following:

1. Take a thin stranded wire, cut off one vein. 2. We wind the wiring on the spring. 3. We bend the wire so that the battery does not break it. The wire should protrude slightly over the curling part of the flashlight. 4. Twist tightly. We break off the excess wire (tear off). As a result, the wire provides good contact with the negative part of the battery and the flashlight will shine with proper brightness. Of course, during such a repair, the button is not a lot, therefore, turning on - turning off the flashlight is done by turning the head part. My Chinese worked like that for a couple of months. If you need to change the battery, back part Do not touch the lamp. We turn our head away.

Today I decided to bring the button back to life. The button is in plastic case which is simply pressed into the back of the lamp. In principle, it can be pushed back, but I did it a little differently:

1. Make a pair of holes with a 2 mm drill bit to a depth of 2-3 mm. 2. Now you can unscrew the housing with the button with tweezers. 3. Extract the button 4. The button is assembled without glue and latches, so it is easy to disassemble it with a clerical knife. The photo shows that the movable contact has oxidized (round bullshit in the center, similar to a button). It can be cleaned with an eraser or fine sandpaper and put the button back together, but I decided to additionally irradiate both this part and the fixed contacts.

1. We clean with fine sandpaper. 2. We serve with a thin layer of the places marked in red. We wipe the flux with alcohol, assemble the button. 3. To increase reliability, I soldered the spring to the bottom pin of the button. 4. Putting everything back. After repair, the button works fine. Of course, tin also oxidizes, but since tin is a fairly soft metal, I hope that the oxide film will break easily when the button is operated. It is not for nothing that the central contact on the bulbs is made of tin.

IMPROVING FOCUSING.

What is a "hotspot", my Chinese person was very vague, so I decided to enlighten him. Unscrew the head part.

1. The board has a small hole (arrow). With the help of an awl, we unscrew the filling, while lightly press the outside of the glass with your finger. This makes it easier to get out. 2. Remove the reflector. 3. We take ordinary office paper, punch 6-8 holes with an office punch. The diameter of the holes of the hole punch perfectly matches the diameter of the LED. Cut out 6-8 paper washers. 4. Put the washers on the LED and press down with the reflector, then you have to experiment with the number of washers. In this way, I improved focusing with a pair of flashlights, the number of washers was in the range of 4-6. It took 6 of them on the current patient.

The Chinese save on everything. A couple of unnecessary details - an increase in the cost price, so they do not put it.

The main part of the diagram (marked in green) can be different. On one or two transistors or on a specialized microcircuit (I have a circuit of two parts: a choke and a microcircuit with 3 legs, similar to a transistor). But on the part marked in red - they save. I added a capacitor and a pair of 1n4148 diodes in parallel (I didn't find a Schottky). The brightness of the LED has increased by 10-15 percent.

remontavto-moto-velo.blogspot.com

Modification of the LED flashlight - RadioRadar

Lighting engineering

Home For radio amateurs Lighting engineering

In the dark, a pocket torch is an irreplaceable thing. However, the commercially available plug-in rechargeable battery samples are disappointing. For some time after purchase, they still work, but then the lead-acid gel battery degrades and one charge starts to suffice for only a few tens of minutes of glow. And often, during charging with the flashlight on, the LEDs burn out one after the other. Of course, given the low price of a flashlight, you can buy a new one every time, but it is more expedient to understand the reasons for the failures once, eliminate them in the existing flashlight and forget about the problem for many years.

Consider in detail the one shown in Fig. 1 diagram of one of the failed lamps and determine its main disadvantages. To the left of the GB1 battery is the unit responsible for charging it. The charging current is set by the capacitance of the capacitor C1. Resistor R1, installed in parallel with the capacitor, discharges it after disconnecting the flashlight from the network. The red LED HL1 is connected through a limiting resistor R2 in parallel to the lower left diode of the VD1-VD4 rectifier bridge in reverse polarity. The current through the LED flows during those half-periods of the mains voltage in which the upper left diode of the bridge is open. Thus, the glow of the HL1 LED only indicates that the flashlight is connected to the network, and not about the ongoing charging. It will glow even if the battery is missing or faulty.

The current consumed by the flashlight from the mains is limited by the capacitance of the capacitor C1 up to approximately 60 mA. Since part of it branches off into the HL1 LED, the charging current for the GB1 batteries is about 50 mA. The XS1 and XS2 sockets are for measuring battery voltage.

Resistor R3 limits the battery discharge current through the parallel-connected EL1-EL5 LEDs, but its resistance is too low, and a current exceeding the rated current flows through the LEDs. The brightness from this increases slightly, and the degradation rate of LED crystals increases markedly.

Now about the reasons for the burnout of LEDs. As you know, when charging an old lead-acid battery, the plates of which were sulfated, an additional voltage drop occurs at its increased internal resistance. As a result, when charging is in progress, the voltage at the terminals of such a battery or their battery may be 1.5 ... 2 times higher than the nominal. If at this moment, without stopping charging, close the SA1 switch to check the brightness of the LEDs, then the increased voltage will be sufficient to significantly exceed the permissible current through them. The LEDs will fail one by one. As a result, burned-out LEDs are added to the battery unusable for further operation. It is impossible to repair such a flashlight - there are no spare batteries on sale.

The proposed lantern modification scheme, shown in Fig. 2, allows you to eliminate the described shortcomings and exclude the possibility of failure of its elements in case of any erroneous actions. It consists in such a change in the scheme for connecting the LEDs to the battery so that its charging is interrupted automatically. This is achieved by replacing the SA1 switch with a switch. The limiting resistor R5 is selected so that the total current through the EL1-EL5 LEDs at a GB1 battery voltage of 4.2 V is 100 mA. Since the SA1 switch is a three-position switch, it became possible to implement an economical mode of lowered brightness of the flashlight by adding a resistor R4 to it.

The indicator on the HL1 LED has also been redesigned. Resistor R2 is connected in series with the battery. The voltage falling across it when the charging current flows is applied to the LED HL1 and the limiting resistor R3. Now, it is the charging current flowing through the GB1 battery that is indicated, and not just the presence of the mains voltage.

The unusable gel battery is replaced by a three-piece Ni-Cd battery with a capacity of 600 mAh. The duration of its full charge is about 16 hours, and it is impossible to spoil the battery without stopping charging in time, since the charging current does not exceed a safe value, numerically equal to 0.1 of the nominal capacity of the battery.

Instead of the burnt ones, HL-508h338WC LEDs with a diameter of 5 mm of white glow with a nominal brightness of 8 cd at a current of 20 mA (maximum current - 100 mA) and an angle of radiation of 15 ° are installed. In fig. 3 shows the experimental dependence of the voltage drop across such an LED on the current flowing through it. Its 5mA value corresponds to an almost completely discharged GB1 battery. Nevertheless, the brightness of the flashlight in this case remained sufficient.

The lantern, converted according to the considered scheme, has been successfully operating for several years. A noticeable decrease in the brightness of the glow occurs only when the battery is almost completely discharged. This just serves as a signal to charge it. As you know, fully discharging Ni-Cd batteries before charging increases their longevity.

Among the disadvantages of the considered refinement method, one can note the rather high cost of a battery of three Ni-Cd batteries and the difficulty of placing it in the body of the lantern instead of the standard lead-acid one. The author had to cut the outer membrane of the new battery in order to more compactly accommodate the batteries that form it.

Therefore, when finalizing one more flashlight with four LEDs, it was decided to use only one Ni-Cd battery and a LED driver on a ZXLD381 microcircuit in a SOT23-3 package http://www.diodes.com/datasheets/ ZXLD381.pdf. With an input voltage of 0.9 ... 2.2 V, it provides LEDs with a current of up to 70 mA.

In fig. 4 shows the power supply circuit for HL1-HL4 LEDs using this microcircuit. The graph of the typical dependence of their total current on the inductance of the inductor L1 is shown in Fig. 5. With its inductance 2.2 μH (a DLJ4018-2.2 choke is used), each of the four parallel-connected EL1-EL4 LEDs has 69/4 = 17.25 mA of current, which is quite enough for their bright glow.

Of the other attachments, only a Schottky diode VD1 and a capacitor C1 are required for the operation of the microcircuit in the mode of a smoothed output current. It is interesting that on the typical diagram of the application of the ZXLD381 microcircuit, the capacity of this capacitor is 1 F. The battery charging unit G1 is the same as in Fig. 2. The limiting resistors R4 and R5 available in the same place are no longer needed, and two positions are enough for the SA1 switch.

Due to the small number of parts, the lantern was reworked as a hinged mounting. The G1 battery (Ni-Cd, AA size, 600 mAh) is installed in the corresponding holder. In comparison with the lantern modified according to the diagram in Fig. 2, the brightness turned out subjectively somewhat lower, but quite sufficient.

Date of publication: 31.05.2013

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One of these days a neighbor comes to us and brings with him a nice portable lantern.
The flashlight worked for six months, lay idle for six months, now it is needed, but does not work. The flashlight was used in the basement; the light is only above the door, and the distant shelves with jam - pickles are gloomy. The lantern lived in the basement, hung on the jamb under the switch and the socket. The basement is dry, the husband wanted to make a carrying with a light bulb, and a lantern appeared - there was no need for it. While the women were chatting among themselves, I took up the lantern. The lantern was made by the Chinese, there is a helium acid battery,
incandescent halogen lamp, Charger to recharge the battery,
assembled according to a primitive scheme.

Made the necessary measurements of the battery with a multimeter:

Voltage and current are at zero, resistance is infinity. There is no point in fiddling with such a battery, I had the opportunity to try to reanimate with such, but if she died, she died. It was decided to make a simple lamp with an LED, powered by a 220 volt network.
A neighbor brought in a power cord of about five meters with a plug at one end.
Found light at 12 volts,
a workable board from the required charger was also available,
installed only a Zener diode D815D instead of the indicator LED, Yes, the power cord was soldered to the board.
Plugged the plug into the mains and the gentle light of the lantern illuminated the room.
Delov was only worth a ruble and a half, and he received a three-liter jar of pickled vegetables as a present from a neighbor.

usamodelkina.ru

LED torch from 1.5V and below

Blocking - the generator is a generator of short-term impulses repetitive at fairly long intervals.

One of the advantages of blocking generators is their comparative simplicity, the ability to connect the load through a transformer, high efficiency, and connect a sufficiently powerful load.

Block generators are very often used in amateur radio circuits. But we will run an LED from this generator.

Very often on a hike, fishing or hunting, you need a flashlight. But not always there is a rechargeable battery or 3V batteries at hand. This scheme can run the LED at full power from an almost discharged battery.

A little about the scheme. Details: Any transistor (n-p-n or p-n-p) can be used in my KT315G circuit.

The resistor needs to be selected, but more on that later.

The ferrite ring is not very large.

And the diode is high frequency with low voltage drop.

So, I was cleaning up a drawer in the table and found an old flashlight with an incandescent light bulb, of course, burned out, and recently I saw a diagram of this generator.

And I decided to solder the circuit and put it in a flashlight.

Well, let's get started:

To begin with, we will collect according to this scheme.

We take a ferrite ring (I pulled out a fluorescent lamp from the ballast) and wind 10 turns with a wire of 0.5-0.3 mm (it can be thinner, but it will not be convenient). We wound it, we make a loop, well, or a bend, and we wind another 10 turns.

Now we take the KT315 transistor, LED and our transformer. We collect according to the scheme (see above). I also put a capacitor in parallel with the diode, so it shone brighter.

So they collected it. If the LED is off, reverse the polarity of the battery. Still off, check if the LED and transistor are connected correctly. If everything is correct and still does not burn, then the transformer is not wound correctly. To be honest, my scheme also started up far from the first time.

Now we supplement the diagram with the rest of the details.

Putting the diode VD1 and the capacitor C1, the LED will light up brighter.

The last step is the selection of the resistor. Instead of a constant resistor, we put a variable at 1.5 kOhm. And we begin to twist. You need to find the place where the LED shines brighter, while you need to find a place where if you increase the resistance at least a little, the LED goes out. In my case, it is 471 ohms.

Okay, now more to the point))

We disassemble the flashlight

Cut out a circle from a one-sided thin fiberglass to the size of the flashlight tube.

Now we go and look for details of the required denominations in the size of a few millimeters. KT315 transistor

Now we mark the board and cut the foil with a clerical knife.

We trick the fee

We fix the jambs, if any.

Now, in order to solder the board, we need a special tip, if not, it doesn't matter. We take a wire 1-1.5 mm thick. We clean it thoroughly.

Now we wind on the existing soldering iron. The end of the wire can be sharpened and tinned.

Well, let's start soldering the details.

You can use a magnifying glass.

Well, everything seems to be soldered, except for the capacitor, LED and transformer.

Now test run. We attach all these details (without soldering) to the "snot"

Hooray!! Happened. Now you can solder all the details without fear.

I suddenly wondered what the output voltage was, I measured

3.7V is normal for a high power LED.

The most important thing is to solder the LED))

We insert it into our flashlight, when I inserted it, I soldered off the LED - it got in the way.

And so, put in, made sure that everything crawls freely. Now we take out the board and cover the edges with varnish. So that there is no short circuit, because the body of the flashlight is a minus.

Now we solder the LED back and check it again.

We checked it, everything works !!!

Now we carefully insert all this into the flashlight and turn it on.

Such a flashlight can be started even from a discharged battery, and if there are no batteries at all (for example, in the forest while hunting). There's a lot different ways get a small voltage (insert 2 wires of different metals into the potato) and start the LED.

Good luck!!!

sdelaysam-svoimirukami.ru

BATTERY LED

It was evening, there was nothing. And I started cleaning up my deposits of radio components and other electronic things accumulated in the area of ​​the table. Some in the barn, and some in the sofa. And I came across a simple burnt-out LED flashlight with a battery charging from a built-in transformerless rectifier in the process of putting things in order.

Since the LEDs themselves turned out to be alive, and the case seemed to be nothing, I decided to bring it to working condition. Of course, not according to the original Chinese scheme, but on a more perfect one. As planned, the updated rechargeable LED flashlight will be charged from the mains and shine for up to 20 hours from a lithium ionic (at a current of 50mA).

Do not be afraid - you do not need to solder expensive parts :) For these purposes, a ready-made charger from any mobile phone(lost a month ago) and also any mobile lithium-ion battery (they gave a phone drowned in the sea for spare parts).

What needs to be done? Just connect the charger to the battery, and it, in turn, to the LEDs.

Since there was a small square hole in the flashlight for an additional LED, I closed it with a piece of dark plexiglass, placing a red LED under it indicating that it was connected to the network for recharging. The LED turns on in parallel with the charger outputs.

The native plug of the lantern was lost, so I had to make a new one, having previously sawed it off from the above charger, from which the scarf was removed.

As you can see, there is enough space in the case for both the charger and other components of the LED flashlight.

When installing, keep in mind that if the battery is directly soldered to the charging, then in the disconnected state there will be a small self-discharge of several milliamps. The way out is simple - put a diode of type IN4001 or similar for a current of more than 0.5A by plus.

Now, when you turn on the flashlight with the toggle switch, the plus of the battery goes through a 20 Ohm resistor to the LEDs. And again by pressing the toggle switch and throwing the plus on the battery - we transfer the flashlight to the mode of charging from the mains.

Despite the fact that a charge controller is installed in the battery itself, I do not recommend leaving the flashlight plugged into the outlet for more than 5 hours. You never know ...

The finished LED rechargeable flashlight turned out to be very nice and easy to use. It shines quite enough for most purposes. Who needs extra power - look at powerful LEDs.

Here, using this simple design as an example, I showed the very principle of altering lanterns using the remains of non-working mobile phones, of which I am sure you have accumulated a considerable amount.

LED Flashlights Forum

Discuss the article BATTERY LED

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We are restoring and bringing to mind a Chinese flashlight. / Workshop / Not Waste

Many have a variety of Chinese flashlights, all powered by a single battery. Like this: Unfortunately, they are very short-lived. How to bring the flashlight back to life and some simple improvements that can improve such flashlights - I will tell you later. The weakest point of such lights is the button. Its contacts are oxidized, as a result of which the flashlight begins to shine dimly, and then it may stop turning on altogether. The first sign is that the flashlight with a normal battery shines weakly, but if you click the button several times, the brightness increases. The easiest way to make such a lantern shine is to proceed as follows: 1. Take a thin stranded wire, cut off one vein. 2. We wind the wiring on the spring. 3. Bend the wire so that the battery does not break it. The wire should protrude slightly above the curled part of the flashlight. 4. Tighten tightly. We break off the excess wire (tear off). As a result, the wire provides good contact with the negative part of the battery and the flashlight will shine with proper brightness. Of course, in such a repair, the button remains irrelevant, therefore, turning on and off the flashlight is done by turning the head part. My Chinese man worked like this for a couple of months. If you need to change the battery, do not touch the back of the flashlight. We turn our head away.

RESTORING THE PERFORMANCE OF THE BUTTON.

Today I decided to bring the button back to life. The button is in a plastic case, which is simply pressed into the back of the flashlight. In principle, it can be pushed back, but I did it a little differently: 1. We make a pair of holes with a 2 mm drill bit to a depth of 2-3 mm. 2. Now you can unscrew the housing with the button with tweezers. 3. Extract the button 4. The button is assembled without glue and latches, so it is easy to disassemble it with a clerical knife. The photo shows that the movable contact has oxidized (round garbage in the center, similar to a button). It can be cleaned with an eraser or fine sandpaper and put the button back together, but I decided to additionally irradiate both this part and the fixed contacts. 1. We clean with fine sandpaper. 2. We serve with a thin layer of the places marked in red. We wipe the flux with alcohol, assemble the button. 3. To increase reliability, I soldered the spring to the bottom pin of the button. 4. Putting everything back. After repair, the button works fine. Of course, tin also oxidizes, but since tin is a fairly soft metal, I hope that the oxide film will break easily when the button is operated. It is not for nothing that the central contact on the bulbs is made of tin.

IMPROVING FOCUSING.

What is a "hotspot", my Chinese person was very vague, so I decided to enlighten him. Unscrew the head. 1. The board has a small hole (arrow). With the help of an awl, we unscrew the filling, while lightly press the outside of the glass with your finger. This makes it easier to get out. 2. Remove the reflector. 3. We take ordinary office paper, punch 6-8 holes with an office punch. The diameter of the holes of the hole punch perfectly matches the diameter of the LED. Cut out 6-8 paper washers. 4. Put the washers on the LED and press down with the reflector, then you have to experiment with the number of washers. In this way, I improved focusing with a pair of flashlights, the number of washers was in the range of 4-6. On the current patient, it took 6 of them, which turned out in the end: On the left - our Chinese, on the right - Fenix ​​LD 10 (at a minimum). The result is quite pleasant. The hot spot has become pronounced and even.

INCREASE BRIGHTNESS (for those who know a little about electronics).

The Chinese save on everything. A couple of extra details - an increase in the cost price, so they do not put it. The main part of the diagram (marked in green) may be different. On one or two transistors or on a specialized microcircuit (I have a circuit of two parts: a choke and a microcircuit with 3 legs, similar to a transistor). But on the part marked in red - they save. I added a capacitor and a pair of 1n4148 diodes in parallel (I didn't find a Schottky). The brightness of the LED has increased by 10-15 percent.

1. This is how the LED looks like in similar Chinese. From the side you can see that there are thick and thin legs inside. A thin leg is a plus. You need to navigate by this sign, because the colors of the wires can be completely unpredictable. 2. This is how the board looks like, to which the LED is soldered (on the back side). Foil is marked in green. The wires from the driver are soldered to the LED legs. 3. Use a sharp knife or a triangular file to cut the foil on the plus side of the LED, sand the entire board to remove the varnish. 4. We solder the diodes and the capacitor. I took the diodes from the broken one computer unit power supply, the tantalum capacitor dropped out of some burned-out hard drive. The plus wire now needs to be soldered to the pad with diodes.

As a result, the flashlight produces (by eye) 10-12 lumens (see photo with hotspots), judging by the phoenix, which produces 9 lumens in the minimum mode.

And the last thing: the advantage of the Chinese over the branded flashlight (yes, don't laugh) Branded flashlights are designed to use rechargeable batteries, so my Fenix ​​LD 10 simply does not turn on with a battery discharged to 1 volt. I took a dead alkaline battery computer mouse... The multimeter showed that she sat down to 1.12v. The mouse on it no longer worked, Fenix, as I said, did not start. But the Chinese man works! Left - Chinese, right - Fenix ​​LD 10 at minimum (9 lumens). Unfortunately, the white balance is knocked out. The phoenix has a temperature of 4200K. The Chinese man is blue, but not as bad as in the photo. For the sake of interest, I tried to finish off the battery. At this brightness level (5-6 lumens per eye), the flashlight worked for about 3 hours. The brightness is quite enough to illuminate under your feet in a dark entrance / forest / basement. Then for another 2 hours the brightness decreased to the level of the "firefly". Agree, 3-4 hours with acceptable light can solve a lot. For this, let me take my leave. Star4ok.

Hh004F wiring diagram

Light sensor connection diagram for lighting

Battery charger with automatic shutdown

Most of the simplest NiCad battery chargers, such as flashlights, do not automatically stop charging. The LED signaling its progress often continues to glow (sometimes with reduced brightness) even after the battery is fully charged. So, there is a danger of failure of some elements of the charger connected to the network if the contact in the circuit of the charged battery is broken.

The proposed device, the diagram of which is shown in the figure, is devoid of these disadvantages due to slight complication. Charging automatically stops when the battery voltage reaches the specified value.

The charging current depends on the capacity of the "quenching" capacitor C1. The use of a full-wave rectifier (diode bridge VD1-VD4) made it possible to halve the capacity of this capacitor in comparison with that required with a half-wave rectifier. This makes it possible to use a smaller capacitor. While VS1 is closed, rectified current flows through the HL1 LED and charges the GB1 battery. When the LED is on, it signals that charging is in progress.

The opening voltage of the VS1 SCR depends on the values ​​of the resistors R4 and R5. As soon as it is reached, the SCR opens, the voltage drop across it will become less than the battery voltage. The HL1 LED will turn on in reverse polarity. All rectified current will now flow through the SCR, and not through the LED and battery. Charging stops and the LED turns off.

Thanks to the capacitor C2, the current through the SCR does not drop to zero at the end of each half-cycle of the mains voltage, which could lead to the closure of the SCR. It remains open until the device is disconnected from the network. The SCR will also open in case of accidental or deliberate disconnection of the battery, preventing the voltage on the capacitor C2 from exceeding the permissible value and thereby protecting it and the diodes VD1-VD4 from breakdown.

To establish the device, instead of a constant resistor R4, a variable with a resistance of 100 kΩ is temporarily installed in it and a partially charged battery of three nickel-cadmium batteries is connected, in series with which a variable resistor with a resistance of 100 ... 200 Ohm is connected. The battery is switched on for charging, and the total voltage across it and the series variable resistor is set equal to 4.3 ... 4.4 V with its slider, which corresponds to the recommended in the article

Slowly reducing the resistance of the variable resistor that replaced R4, the LED HL1 is turned off. The variable resistor is soldered off, its resistance is measured and replaced with a constant of the nearest denomination. Next, the engine of the variable resistor connected in series with the battery is set to a minimum, and charging is started again. By gradually increasing the resistance of this resistor, make sure that the LED turns off, and charging stops at the same voltage across the battery and resistor as in the first case. Now you can, by eliminating the variable resistor, connect the battery directly to the charger.

Capacitor C1 must be designed to operate at an alternating voltage with a frequency of 50 Hz of at least 250 V. Note that the capacitors, as a rule, indicate the permissible constant voltage. It must be at least 630 V. The capacitance of the capacitor is chosen at the rate of 0.1 μF for every 6 mA of charging current (at a voltage of 220 V). Diodes and SCRs can be any, with a certain margin, the charging current of the battery and the voltage of a fully charged battery, preferably small.

Trinistor KU103A can be replaced with a more modern and having a lower control current, for example KU112A. If its false inclusions are observed under the influence of noise, it is recommended to connect a ceramic or film capacitor with a capacity of 0.01 ... 0.1 μF between the terminals of the cathode and the anode of the SCR.

The author used the described device to charge a battery of an unknown type installed in a pocket flashlight, according to appearance and dimensions similar to D-0.26 batteries. When installing and adjusting the charger, it should be remembered that all its elements are under mains voltage.

In the life of every person there are times when lighting is needed, but there is no electricity. It can be a banal power outage, and the need to repair the wiring in the house, and possibly a forest trip or something like that.

And, of course, everyone knows that in this case, only an electric flashlight will help out - a compact and at the same time functional device. Now on the electrical engineering market there are many different types of this product. These are ordinary lamps with incandescent lamps, and LED, with rechargeable batteries and batteries. And there are a great many firms producing these devices - "Dick", "Lux", "Cosmos", etc.

But what is the principle of its work, not many people think. And meanwhile, knowing the device and circuitry of an electric flashlight, you can, if necessary, repair it or even assemble it with your own hands. Let's try to figure it out in this issue.

The simplest lanterns

Since flashlights are different, it makes sense to start with the simplest - with a battery and an incandescent lamp, and also consider it possible malfunctions... The scheme of such a device is elementary.

In fact, there is nothing in it except a battery, a power button and a light bulb. And therefore there are no special problems with him. Here are some possible minor annoyances that could lead to the failure of such a flashlight:

• Oxidation of any of the contacts. These can be contacts of a switch, a light bulb, or a battery. You just need to clean these circuit elements, and the device will work again.
• Burnout of an incandescent lamp - everything is simple here, replacing the light element will solve this problem.
• Full discharge of batteries - replacement of batteries with new ones (or charging, if they are rechargeable).
• Loss of contact or broken wire. If the flashlight is no longer new, then it makes sense to change all the wires. This is not at all difficult to do.

LED flashlight

This type of lantern has a more powerful luminous flux and at the same time consumes very little energy, which means that the batteries in it will last longer. It's all about the design of the light elements - there is no filament in LEDs, they do not consume energy for heating, in view of this, the efficiency of such devices is 80-85% higher. The role of additional equipment in the form of a converter with the participation of a transistor, a resistor and a high-frequency transformer is also great.

If the flashlight battery is built-in, then a charger is included with it.

The circuit of such a flashlight consists of one or more LEDs, a voltage converter, a switch and a battery. In earlier flashlight models, the amount of energy consumed by LEDs had to match that of the source.

Now this problem has been solved by using a voltage converter (also called a multiplier). Actually, it is he who is the main part, which contains the electrical circuit of the flashlight.

If you want to make such a device with your own hands, there will be no particular difficulties. Transistor, resistor and diodes are not a problem. The hardest part will be winding a high frequency transformer on a ferrite ring called a blocking generator.

But this can also be dealt with by taking a similar ring from a faulty electronic ballast of an energy-saving lamp. Although, of course, if you don't want to mess around or don't have time, then you can find highly efficient converters on sale, such as the 8115. With their help, using a transistor and a resistor, it became possible to manufacture an LED flashlight on one battery.

The very same circuit of the LED flashlight is similar to the simplest device, and you should not dwell on it, since even a child is able to assemble it.

By the way, when using a voltage converter in the circuit on an old, simplest flashlight, powered by a 4.5 volt square battery, which you cannot buy now, you can safely put a 1.5 volt battery, that is, the usual "finger" or "little finger" battery. There will be no loss in the luminous flux. The main task in this case is to have at least the slightest idea of ​​radio engineering, literally at the level of knowledge of what a transistor is, and also to be able to hold a soldering iron in your hands.

Refinement of Chinese lanterns

Sometimes it happens that a purchased (seemingly quite high-quality) flashlight with a battery completely fails. And it is not at all necessary that the buyer is to blame for improper operation, although this also occurs. More often it is a mistake when assembling a Chinese flashlight in pursuit of quantity at the expense of quality.

Of course, in this case, you will have to redo it, somehow modernize it, because the money has been spent. Now you need to understand how to do this and whether it is possible to deal with Chinese manufacturer and repair such a device yourself.

Considering the most common option, in which when the device is turned on to the network, the charging indicator glows, but the flashlight does not charge and does not work, you can notice this.

A common manufacturer's mistake is that the charge indicator (LED) is included in the circuit in parallel with the battery, which should not be allowed. At the same time, the buyer turns on the flashlight, and seeing that it does not burn, again supplies power to the charge. As a result, all LEDs burn out at once.

The fact is that not all manufacturers indicate that it is impossible to charge such devices with the LEDs on, since it will be impossible to repair them, all that remains is to replace them.

So, the task of modernization is to connect the charge indicator in series with the battery.

As you can see from the diagram, this problem is quite solvable.

But if the Chinese put a 0118 resistor in their product, then the LEDs will have to be changed constantly, since the current supplied to them will be very high, and no matter what light elements are installed, they will not withstand the load.

LED headlamp

In recent years, such a light device has become quite widespread. Indeed, it is very convenient when the hands are free, and the beam of light hits where the person is looking, this is precisely the main advantage of the headlamp. Previously, only miners could boast of this, and even then, to wear it, they needed a helmet, on which the lantern, in fact, was attached.

Now the fastening of such a device is convenient, it can be worn under any circumstances, and a rather voluminous and heavy battery does not hang on the belt, which, moreover, must also be charged once a day. The modern one is much smaller and lighter, moreover, it has very low energy consumption.

So what exactly is such a lantern? And the principle of its operation is not at all different from the LED. Execution options are the same - rechargeable or with removable batteries. The number of LEDs varies from 3 to 24 depending on the characteristics of the battery and inverter.

In addition, such lights usually have 4 glow modes, and not one. It is weak, medium, strong and signaling - when the LEDs blink at short intervals.

The modes of the LED headlamp are controlled by a microcontroller. Moreover, if it is available, even a stroboscope mode is possible. In addition, this does not harm the LEDs at all, unlike incandescent lamps, since their service life does not depend on the number of on-off cycles due to the absence of an incandescent filament.

So which lantern should you choose?

Of course, flashlights can be different in terms of the voltage consumed (from 1.5 to 12 V), and with different switches (touch or mechanical), with the presence of a sound notification of the battery discharge. It can be the original or its analogues. And it is not always possible to determine what kind of device is in front of your eyes. After all, until it fails and its repair begins, it is impossible to see what kind of microcircuit or transistor is in it. It's probably better to choose the one you like, and possible problems decide as soon as it arrives.

Let's take a rechargeable flashlight from DiK, Lux or Cosmos as a sample (see photo). This pocket flashlight is compact, comfortable in the hand and has a fairly large reflector - 55.8 mm in diameter, the LED matrix of which has 5 white LEDs, which provides a good and large illumination spot.

In addition, the shape of the flashlight is familiar to everyone, and to many from childhood, in one word - the brand. The charger is located inside the flashlight itself; you just need to remove the cover from the back and plug it into an outlet. But, nothing stands still and this design of the flashlight has also undergone changes, especially its inner filling... Latest model on this moment- DIK AN 0-005 (or DIK-5 EURO).

More early versions- these are DIK AN 0-002 and DIK AN 0-003 differ in that they contained disk batteries (3 pcs), Ni-Cd series D-025 and D-026, with a capacity of 250 mA / hour, or in model AN 0 -003 - assembly of newer D-026D batteries with a larger capacity, 320 mA / h and incandescent bulbs of 3.5 or 2.5 V, with a current consumption of 150 and 260 mA, respectively. The LED, for comparison, consumes about 10 mA and even a matrix of 5 pieces is 50 mA.

Of course, with such characteristics, the flashlight could not shine for a long time, its maximum was enough for 1 hour, especially the first models.

What is it about latest model flashlight DIK AN 0-005?

Well, firstly - an LED matrix of 5 LEDs, as opposed to 3 or incandescent bulbs, which gives much more light with a lower current consumption, and secondly - in the flashlight there is only 1 finger modern Ni-MH battery for 1.2 -1.5 V and capacity from 1000 to 2700 mAh.

Some will ask, how can a 1.2 V finger battery "light up" the LEDs, because they need about 3.5 V to shine brightly? For this reason, in earlier models, 3 batteries were installed in series and received 3.6 V.

But, here I don't know who was the first to invent, the Chinese or someone else, to make a voltage converter (multiplier) from 1.2 V to 3.5 V. The circuit is simple, in Chinese flashlights these are just 2 parts - a resistor and a radio component similar for a transistor marked - 8122 or 8116, or SS510, or SK5B. SS510 is a Schottky diode.

Such a flashlight shines well, brightly, and what is not unimportant - for a long time, and the charge-discharge cycles are not 150, as in previous models, but much more, which increases the service life at times. But!! In order for the LED flashlight to serve for a long time, you need to plug it into a 220 V outlet when it is off! If this rule is not followed, then when charging, you can easily burn out the Schottky diode (SS510), and often LEDs at the same time.

I once had to repair a DIK AN 0-005 flashlight. I do not know exactly what caused it to fail, but I assume that they plugged it into an outlet and forgot it for several days, although according to the passport it is necessary to charge no more than 20 hours. In short, the battery failed, flowed, and 3 out of 5 LEDs burned out, plus the converter (diode) also stopped working.

I had a 2700 mAh finger battery, it was left from an old camera, LEDs too, but finding a part - SS510 (Schottky diode) turned out to be problematic. This LED flashlight is most likely of Chinese origin, and such a part can probably only be bought there. And then I decided to blind the voltage converter from those parts that are, i.e. from domestic: transistor KT315 or KT815, high-frequency transformer and others (see diagram).

The circuit is not new, it has existed for a long time, I only used it in this flashlight. True, instead of 2 radio components, like the Chinese, I got 3, but free.

The electrical circuit, as you can see, is an elementary, the most difficult thing is to wind the HF transformer on a ferrite ring. The ring can be used from an old switching power supply, from a computer, or from an energy-saving non-working light bulb (see photo).

The outer diameter of the ferrite ring is 10-15 mm, the thickness is approximately 3-4 mm. It is necessary to wind 2 windings of 30 turns with a wire of 0.2-0.3 mm, that is, we wind first 30 turns, then we make a branch from the middle and another 30. If you take the ferrite ring from the board of a fluorescent lamp - it is better to use 2 pieces, fold them together. On one ring, the circuit will also work, but the glow will be weaker.

I compared 2 flashlights for a glow, the original (Chinese) and converted according to the above scheme - I almost did not see any differences in brightness. The converter, by the way, can be inserted not only into a rechargeable flashlight, but also into a regular one, which runs on batteries, then it will be possible to power it from just 1 battery of 1.5 V.

The charger circuit of the flashlight has hardly changed, with the exception of the denominations of some parts. The charging current is approximately 25 mA. When charging, the flashlight must be turned off! And do not turn on the switch while charging, since the charging voltage is more than 2 times higher than the battery voltage, and if it goes to the converter and increases, the LEDs will have to be partially or completely changed ...

In principle, according to the above scheme, an LED flashlight can be easily made with your own hands, by mounting it, for example, in the body of some old, even the most ancient flashlight, or you can make the body yourself.

And in order not to change the structure of the switch of the old flashlight, where a small incandescent light bulb of 2.5-3.5 V was used, you need to break the already burned out light bulb and solder 3-4 white LEDs to the base, instead of a glass bulb.

And also, for charging, mount the connector under the power cord, from an old printer or receiver. But, I want to draw your attention, if the body of the flashlight is metal - do not mount the charger there, but make it portable, i.e. separately. It is not at all difficult to remove the finger battery from the flashlight and insert it into the charger. And don't forget to isolate everything well! Especially in those places where there is a voltage of 220 V.

I think that after the alteration, the old flashlight will serve you for more than one year ...