Hello! Today we will see how to repair a Chinese LED lantern at home with our own hands. We will spend at the same time a minimum of family budget funds. Did you know that the first electric flashlight was not Chinese at all. It was invented in 1896 by American David Meizell. He patented an electric lantern, the body of which was made of wood with a carrying handle. By this time, the zinc battery and the incandescent lamp had already been invented, so the flashlight was a matter of time. Popular today Chinese LED lantern PM-0107 can be bought for literally a couple of hundred rubles. This will already be a flashlight with built-in charging from a 220 volt network. Today we will see how to fix the frequent breakdowns of such a Chinese lantern at home with our own hands. The backstory from Master Sergey is as follows: the owner of the flashlight turned it on for charging and accidentally touched the flashlight switch.
Flashlight malfunction
Flashlight flickered on and off. At the same time, it was possible to break out part of the plug to charge it from the network. Well, let's see how to fix such a miracle of Chinese industry. This is very easy to disassemble - you need to unscrew the three screws and push the two halves of the plastic body of the lamp.
Inside we see a battery, a board with seven LEDs and a reflector. There is a light mode switch and a battery charging board with a connected 220 volt plug. To make it more convenient to repair our simplest, we disassemble it thoroughly, pulling out all the elements on the table.
Particular attention should be paid to the mains charging board - check the condition of the rectifier diodes, the indicator green LED and the high-voltage capacitor. It does not hurt to check the operation of the flashlight mode switch button.
We thoroughly check the LEDs on the round board.
Four LEDs are burned out
We solder the wires in place and check the power circuit assembly.
Good day to all. There was a flashlight with a diode matrix for 16 LEDs lying around at home, I wanted to remake it in the sense of improving the power supply circuit, all the more so. By itself, the matrix shines quite brightly, but still not the way they say. I took a 1 W LED with a 60-degree collimator as a basis, as a LED driver I took the circuit I already cited in.
Scheme number 1
Of course, I chose a SAMSUNG 18650 2600ma / h lithium battery as a power source.
For the battery discharge controller, I used a specialized controller, which is in the battery of mobile phones - a microcircuit DW01-P with a field effect transistor.
The task was to push all this economy without altering the lamp housing, since there was very little free space, or rather, there was none at all, except inside the threaded nut that fastens the native diode matrix in the housing. I placed the whole thing on two printed circuit boards: on the first, the battery discharge controller itself, on the second light-emitting diode driver. The LED is soldered to an aluminum substrate and is pressed against the lamp body with the same threaded nut. Since the nut has direct thermal contact with the LED substrate and the flashlight body, which is also made of aluminum, we have an excellent heatsink.
Discuss the article SCHEME OF A FLASHLIGHT ON LEDS
As a sample, we take a rechargeable flashlight from DiK, Lux or Cosmos (see photo). This pocket flashlight is small, handy 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 spot of illumination.
In addition, the shape of a flashlight is familiar to everyone, and to many since childhood, in a word - a brand. The charger is located inside the flashlight itself, you just need to remove the back cover and plug it into a power outlet. But, nothing stands still, and this flashlight design has also undergone changes, especially its internal filling. The latest model at the moment is DIK AN 0-005 (or DiK-5 EURO).
The earlier versions 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 / h, or models AN 0-003 - assembly of newer batteries D-026D with a larger capacity, 320 mAh and incandescent bulbs for 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 there in the latest flashlight model DIK AN 0-005?
Well, firstly - an LED matrix of 5 LEDs, unlike 3 or incandescent bulbs, which gives much more light with less current consumption, and secondly, there is only 1 finger modern Ni-MH battery per 1.2 in the flashlight -1.5 V and capacity from 1000 to 2700 mAh.
Some will ask, how can a 1.2 V AA battery “light up” LEDs, because in order for them to shine brightly, about 3.5 V is needed? For this reason, in earlier models, they put 3 batteries in series and got 3.6 V.
But, here I don’t know who first came up with it, 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 lanterns it’s just 2 parts - a resistor and a similar radio component on 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 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 must insert it into a 220 V socket in the off state! If this rule is not followed, then when charging, you can easily burn the Schottky diode (SS510), and often the LEDs at the same time.
I once had to repair a flashlight DIK AN 0-005. I don’t know exactly what caused it to fail, but I assume that they plugged it into a socket and forgot it for several days, although it takes no more than 20 hours to charge according to the passport. In short, the battery failed, it leaked, and 3 out of 5 LEDs burned out, plus the converter (diode) also stopped working.
I had a 2700 mAh finger-type battery, it was left from an old camera, LEDs too, but it turned out to be problematic to find the part - SS510 (Schottky diode). 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 scheme is not new, it has existed for a long time, I just 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 elementary, the most difficult thing is to wind the RF 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, i.e. we wind 30 turns first, then we make a tap from the middle and another 30. If you take the ferrite ring from the board of a fluorescent light bulb, 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 glow, the original (Chinese) and the one remade 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 that runs on batteries, then it will be possible to power it from just 1 1.5 V battery.
The flashlight charger circuit has hardly changed, with the exception of the ratings of some parts. The charging current is approximately 25 mA. When charging, the flashlight must be turned off! And do not click the switch during charging, since the charging voltage is more than 2 times higher than the battery voltage, and if it goes to the converter and intensifies, the LEDs will partially or completely have to be 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 case of some old, even the most ancient flashlight, or you can make the case yourself.
And in order not to change the structure of the switch of the old flashlight, where a small 2.5-3.5 V incandescent bulb 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 a connector for a 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 remote, i.e. separately. It is not at all difficult to remove the AA battery from the flashlight and insert it into the charger. And don't forget to insulate 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 ...
In the dark, a flashlight is an indispensable thing. However, commercially available battery-powered designs are disappointing. Some time after the purchase, they still work, but then the gel lead-acid battery degrades and one charge begins to last only a few tens of minutes of glow. And often during charging with the flashlight on, the LEDs burn out one by one. Of course, given the low price of the flashlight, you can buy a new one every time, but it’s more expedient to figure out the causes of failures once, eliminate them in the existing flashlight and forget about the problem for many years.
Let us consider in detail the one shown in Fig. 1 scheme of one of the failed lamps and determine its main shortcomings. To the left of the GB1 battery, the node responsible for charging it is located here. The charging current is given by the capacitance of the capacitor C1. Resistor R1, installed in parallel with the capacitor, discharges it after the lamp is disconnected from the mains. 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 flows through the LED during those half-cycles 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 defective.
The current consumed by the lamp from the network is limited by the capacitance of the capacitor C1 to approximately 60 mA. Since part of it branches off into the HL1 LED, the charging current of the GB1 batteries is about 50 mA. Sockets XS1 and XS2 are designed to measure battery voltage.
Resistor R3 limits the battery discharge current through the EL1-EL5 LEDs connected in parallel, but its resistance is too low, and a current exceeding the nominal current flows through the LEDs. The brightness from this increases slightly, and the rate of degradation of LED crystals increases markedly.
Now about the causes of LED burnout. As you know, when charging an old lead battery, the plates of which have been sulfated, an additional voltage drop occurs on its increased internal resistance. As a result, during ongoing charging, the voltage at the terminals of such a battery or their battery can be 1.5 ... 2 times higher than the nominal one. 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 current through them of the allowable value. The LEDs will fail one by one. As a result, burned-out LEDs are added to the battery unsuitable for further use. It is impossible to repair such a flashlight - spare batteries are not available for sale.
The proposed scheme for refining the lantern, shown in Fig. 2, allows you to eliminate the described shortcomings and eliminate the possibility of failure of its elements in case of any erroneous actions. It consists in such a change in the scheme of connecting LEDs to the battery so that its charging is interrupted automatically. This is ensured by replacing switch SA1 with a switch. The limiting resistor R5 is chosen so that the total current through the LEDs EL1-EL5 at a battery voltage GB1 of 4.2 V is 100 mA. Since the switch SA1 is used three-position, it became possible to implement an economical mode of reduced brightness of the flashlight by adding resistor R4 to it.
The indicator on the HL1 LED has also been redone. Resistor R2 is connected in series with the battery. The voltage falling on it during the flow of the charging current is applied to the LED HL1 and the limiting resistor R3. Now there is an indication of the charging current flowing through the GB1 battery, and not just the presence of mains voltage.
The unusable gel battery was replaced with three Ni-Cd batteries with a capacity of 600 mAh. The duration of its full charge is about 16 hours, and it is impossible to damage 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 burned out LEDs HL-508H238WC with a diameter of 5 mm white glow with a nominal brightness of 8 cd at a current of 20 mA (maximum current - 100 mA) and an emission angle of 15 ° are installed. On fig. Figure 3 shows the experimental dependence of the voltage drop across such an LED on the current flowing through it. Its value of 5 mA corresponds to an almost completely discharged GB1 battery. Nevertheless, the brightness of the lantern 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, completely discharging Ni-Cd batteries before charging increases their durability.
Among the shortcomings of the considered improvement method, one can note the rather high cost of a battery of three Ni-Cd batteries and the difficulty of placing it in the flashlight body instead of a standard lead-acid one. The author had to cut the outer film shell of the new battery in order to place the batteries forming it more compactly.
Therefore, when finalizing another flashlight with four LEDs, it was decided to use only one Ni-Cd battery and LED driver on the ZXLD381 chip in the SOT23-3 package http://www.diodes.com/datasheets/ZXLD381.pdf. At an input voltage of 0.9 ... 2.2 V, it provides LEDs with a current of up to 70 mA.
On fig. 4 shows the power supply circuit for HL1-HL4 LEDs using this microcircuit. A graph of the typical dependence of their total current on the inductance of the inductor L1 is shown in fig. 5. With its inductance of 2.2 μH (a choke DLJ4018-2.2 was used), each of the four parallel-connected EL1-EL4 LEDs has 69/4 = 17.25 mA current, which is quite enough for their bright glow.
Of the other attachments, for the operation of the microcircuit in the smoothed output current mode, only the Schottky diode VD1 and the capacitor C1 are required. Interestingly, the typical application diagram for the ZXLD381 chip indicates the capacitance 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 there are no longer needed, and two positions are enough for the SA1 switch.
Due to the small number of parts, the modification of the lantern was carried out by surface mounting. The G1 battery (Ni-Cd size AA with a capacity of 600 mAh) is installed in the appropriate holder. Compared with the lantern, modified according to the scheme of Fig. 2, the brightness turned out to be subjectively somewhat lower, but quite sufficient.
Blocking - generator It is a generator of short-term pulses recurring at fairly large intervals of time.
One of the advantages of blocking generators is their relative simplicity, the ability to connect the load through a transformer, high efficiency, and the connection of a sufficiently powerful load.
Blocking oscillators are very often used in amateur radio circuits. But we will run an LED from this generator.
Very often, when hiking, fishing or hunting, you need a flashlight. But not always at hand there is a battery or 3V batteries. This circuit can run the LED at full power from a nearly dead 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 in a drawer in the table and found an old flashlight with an incandescent 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 it out of the ballast of a fluorescent lamp) And we 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 branch, and we wind another 10 turns.
Now we take the KT315 transistor, the LED and our transformer. We collect according to the scheme (see above). I put another capacitor in parallel with the diode, so it shone brighter.
Here they are collected. If the LED does not light up, reverse the polarity of the battery. Still does not light, check the correct connection of the LED and the transistor. If everything is correct and still does not light up, then the transformer is not wound correctly. To be honest, I also got the scheme far from the first time.
Now we supplement the scheme with the rest of the details.
By 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 fixed resistor, we put a variable at 1.5 kOhm. And we start spinning. You need to find the place where the LED shines brighter, while you need to find a place where if you increase the resistance even a little bit, the LED goes out. In my case, this is 471 ohms.
Okay, now to the point))
We disassemble the flashlight
We cut out a circle from one-sided thin fiberglass to fit the size of the flashlight tube.
Now let's go and look for parts of the required denominations a few millimeters in size. Transistor KT315
Now we mark the board and cut the foil with a clerical knife.
Ludim fee
We fix the jambs, if any.
Now, in order to solder the board, we need a special sting, if not, it does not matter. We take a wire 1-1.5 mm thick. We clean 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 normally without fear
I suddenly became interested, what is the voltage at the output, I measured