Era lantern diagram. How to repair a broken LED flashlight. Why do flashlights break?

Dedicated to all those who have similar LED lights.
A typical problem with the latter is a 4-volt lead-acid (AGM) battery that “suddenly” stops working.
Recently there was a review with a solution to a similar problem. .
I took a slightly different path, it will become clear why later.

First, a little about the lanterns:

Budget flashlights with decent sizes and mediocre characteristics. But they continue to be bought and used. The flashlight contains many super-bright 3-5mm LEDs.

LEDs are usually connected in parallel, through current-limiting resistors.

The heart of the flashlight is a lead-acid battery (AGM) with a capacity of up to 4.5Ah.

The unpretentiousness of the battery can be considered a positive point. Possibility of recharging at any time and operation at subzero temperatures. The last point is not taken into account in my modification, since the operation of the flashlight at significant negative temperatures is not planned.

Looking ahead, I’ll say that it took about 2 hours to remake the lantern.

Open the flashlight and remove the dead battery:

To begin with, I measured the current consumption at a battery voltage of 3.84 V:

Resistors are installed in series with the LEDs to limit the current. Due to the changed voltage of the flashlight, it would be possible to lower the resistance of the resistors, but I did not do this. The brightness has dropped slightly, you can live with this, and it’s time-consuming.
At a voltage of 4.2V, the current exceeded 1 A. This became the starting point in solving the problem. There is no need to use a cheap power bank kit due to the latter’s inability to produce the required current.

The solution was on the surface:
Two board options, one with overdischarge protection, the other without protection:

A little about the boards. The controller is one of the most common TP4056. I used a similar board. Controller documentation. The controller provides a charging current of up to 1 Ampere, so you can roughly calculate the battery charging time.
Which board to use in your flashlight depends on the type of 18650 elements used. If there is overdischarge protection, then the one on the right. Otherwise, you can assign the battery protection function to the board, which it does an excellent job of. The boards differ from each other by the presence of additional parts, such as a DW01 discharge controller and an 8205 power switch (dual field-effect transistor) to disconnect the battery from the load at the right time or protect it from overcharging.

There is a lot of space inside, you can install at least a dozen batteries, but for testing I made do with one.

The latter was removed from an old laptop battery and tested on an IMAX B6 charger:

With a discharge current of 1 Ampere, the residual capacity is 1400 mAh. This is enough for about an hour and a half of continuous operation of the flashlight.

Let's try to connect the battery to the board:

The wires to the battery must be soldered carefully, without overheating the battery. If you are not sure, you can use a battery holder.

It is also advisable to observe the color differentiation of the pants and use wires of different colors to connect the power.

We connect the board via a micro USB cable to the power supply:

The red LED lights up and the charge has started.

Now you need to install the charge controller board in the flashlight. There are no special fastenings, so we make a collective farm using everyone’s favorite superglue.

Gluing your fingers at least once is the sacred duty of everyone who has used it.

We make a bracket from a suitable metal plate (an element from a children's metal construction set will do).

In order to avoid short circuits, we use insulating material. I used a piece of heat shrink tubing.

I secured the board by first connecting the wires that previously went to the lead battery:

From the outside it looks like this:

Small defects are visible on the sides of the connector. They are corrected as follows: the hole or crack is filled with baking soda and then 1-2 drops of superglue. The glue sets instantly. After 30 seconds, you can use a file to process the surface.
We secure the battery inside using any available method. I used sealant; some people prefer a glue gun.
The charging connector hole will be covered later with a rubber cap.

We assemble and enable:

Works.
Upd: If you plan to connect several batteries in parallel, then before connecting, in order to avoid damage to the latter, it is necessary to bring all batteries to a single EMF (simple voltage).

Conclusions: Costs in money are approximately 100 rubles and 2 hours of time. I don’t take the battery into account; I used a half-dead one with high internal resistance. I get a working flashlight. The procedures I describe are not a panacea; there are other options for modifying flashlights. I did not display an indication of the charging process/readiness on the case. The blue/red LED glow is visible through the housing.
By the way, the board can have any mini or micro USB connector you like. It all depends on the availability of the necessary cables. Among other things, we still have a power supply on hand for charging a lead-acid battery - it will be useful to attach it somewhere.

Pros:
Working light, lighter weight (although this is an insignificant fact). You can charge in any accessible place if you have a USB charger or a computer.
Minuses:
The battery is afraid of frost, the brightness is lower (by about 10-15%) compared to the factory version. At the end of the discharge, the brightness drops, noticeably to the eye. To solve this problem, you can install a more capacious (or several) battery.

Good afternoon to all readers and admirers of the Radioschema website! Today I want to introduce you to another modification of the Chinese lantern.

Once I received an impressively sized plastic case from some Chinese flashlight from an unknown company, completely free of charge. I decided that if it would come in handy, I would do something. Having disassembled it, I found inside a completely dead battery of an unknown manufacturer, there was not a single inscription on it. There were also no light-emitting elements. Well, I put it off until better times.

Battery replacement

Subsequently, a 6 volt 4.5 A/h battery of similar size was purchased. True, its size was a little larger, so the body had to be, as they say, “modified with a file.”

There was obviously some kind of incandescent light bulb at the top of the lantern. Having rummaged around a little with my brains and eyes, I discovered that in place of the latter, a lens from a one-watt LED fits very well. Which, with the help of the same file, successfully fit into this technological hole, along with the same LED. And then two pieces of aluminum profile from sliding furniture doors were glued onto it as a radiator. Initially, I wanted to put a three-watt LED there, but the experience of using such diodes said that my improvised radiator would not have enough cooling area (and a larger one would not fit inside the flashlight), so I decided to go with a one-watt diode.

I wanted to power the LED using . But then I came across a car charger for the phone, as it turned out, built on some Chinese analogue of the same MC34063, since the circuit coincided one to one. I decided to take this board as a basis, unsoldered the USB connector, and replaced the voltage divider with a multi-turn trimmer. I set the current to 270 mA (while the diode is designed for 350 mA - there will be a reserve). The light intensity is quite enough to illuminate a space of 15-20 meters at night.

Installation of LEDs

Further, in the lower part, most likely, there was some kind of fluorescent lamp. Which can be determined by the characteristic protrusions on the reflector. Without hesitation, I decided to install LEDs there that had recently arrived from China:

Everything was done very simply. I marked out the location of the LEDs on checkered paper, glued them to the reflector with paper glue, and drilled holes for the leads with a millimeter drill. I removed the paper, cleaned the reflector with a cloth to remove the glue, inserted the LEDs and bent the legs. Since I didn’t want to sculpt a driver, I decided to limit myself to resistors. I connected all the LEDs in parallel and put a 180 Ohm resistor on each LED; I used SMD resistors for this, which I fused directly into the plastic, since the battery turned out to be too big and there was simply no room for lead elements.

The power switch is located at the top of the handle and has three fixed positions. In the middle position everything is off, in the rearmost position the lower part of the flashlight is on, it gives diffused light. And in the extreme forward position, the upper part turns on and produces a narrowly directed beam of light, plus the lower part is powered to it through a diode soldered to the switch.

Voltage indicator

Then the idea arose to make an indication of the battery charge. I searched the Internet and found this table:

Since my battery is 6 volts, the numbers in the “voltage” column must be divided by two. I decided to build an indicator on the widely used LM324 microcircuit, which is a quad operational amplifier (op-amp). Since I had already soldered a similar circuit for the light indication of a metal detector, I was left with a signet, which later had to be slightly modified. To display information about the state of the battery, I took four values (according to the number of op amps) - 20%, 40%, 60% and 80%. I had to spend half a day just to calculate the voltage divider, I even created a special table for this in Excel to make it easier to calculate.

The button for turning on the indicator is located on the body under the handle; when you press it, the number of LEDs corresponding to the charge lights up. If one is on, then 20%, if all, then 80% or more.

Power Bank

The next function of my flashlight was the ability to charge mobile devices. Since the battery has a good capacity, it is quite capable.

I thought for a long time about how to coordinate the voltage levels of the battery and mobile phone. At first I wanted to make the same converter on the MC34063, but it didn’t fit due to the small voltage difference. There was an option to install the LM7805, but again it was not suitable for the same reason. As a result, after talking with my radio amateur friends on our forum (for which I thank them very much!) I came to the conclusion that you can use an ordinary resistor that will limit the current, and by simple manipulations with Ohm’s law, this element was calculated. It turned out 3 Ohms 1 W.

Charge indicator

Next, it is planned to modernize the flashlight by installing a solar panel on the side surface of the body to constantly recharge the battery. After all, most of the time the flashlight is off. You will get such a portable, autonomous mini power station. For charging mobile phones and lighting. On this cheerful note, let me take my leave, see you again on the pages of the site! Author - Temych (Artem Bogatyr)

Discuss the article HOW TO IMPROVE A CHINESE LANTERN

Flashlight circuit with battery

As a radio mechanic, I am interested in the simplest electronic devices. This time we will talk about a flashlight with a battery.

Here is a diagram of a flashlight with a battery.

The flashlight consists of two parts. In one part there is a battery and a mains charger, and in the other there is a switch and an incandescent lamp. To charge the battery, one part of the flashlight is disconnected from the head (where the lamp and switch are) and connected to a 220V network.

The photo shows an adapter connector that connects the battery and the switch to the incandescent lamp.

The design of such a flashlight is extremely simple. To charge a lead-acid battery G1 with a capacity of 1 A/h (1 ampere-hour) and a voltage of 4V, a circuit with a quenching capacitor C1 is used. Most of the 220V network voltage drops on it. Then the alternating voltage after the quenching capacitor is rectified by a diode bridge using diodes VD1 - VD4 (1N4001).

To smooth out ripples, an electrolytic capacitor C2 is installed after the diode bridge. The load for this entire rectifier is battery G1. If you turn it off, the rectifier output will have a voltage of about 300 volts, although when the battery is connected, the voltage at its output is 4 - 4.5 volts.

It is worth noting that the circuit with a damping (ballast) capacitor is simple, but quite dangerous. The fact is that such a circuit is not galvanically isolated from the 220 volt network. When using a transformer, the circuit becomes more electrically safe, but due to the high cost of this part, a circuit with a quenching capacitor is used.

The VD5 diode is necessary so that when the circuit is disconnected from the network, the battery does not discharge through the rectifier circuit and indication on the red LED HL1 and resistor R2. But the EL1 incandescent lamp (or a circuit of LEDs) is connected to the battery only through switch SA1. It turns out that the VD5 diode serves as a kind of barrier that passes current to the battery from the mains rectifier, but not back. This is such a simple defense. It is also worth saying that a small part of the rectified voltage is lost on the VD5 diode - due to the voltage drop across the diode when connected directly ( V F). It is somewhere between 0.5 - 0.7 volts.

I would also like to say something about the battery. As stated, it is sealed lead acid (Pb). Consists of two 2 volt cells connected in series. That is, the battery, as they say, consists of 2 cans.

The battery indicates that the maximum charge current is 0.5 amperes. Although for lead Pb batteries it is recommended to limit the charge current to 0.1 of its capacity. Those. for this battery, the best charging current will be 100mA (0.1A).

Typical problems with battery-powered flashlights are:

Failure of mains rectifier elements (diodes, electrolytic capacitor, resistor in the indication circuit);

Malfunction of the switch button (easily repaired by any suitable latching button or rocker switch);

Battery degradation (aging);

Worn contact connectors.

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

As you can see, the scheme is simple. Main elements: current-limiting capacitor, rectifier diode bridge with four diodes, battery, switch, super-bright LEDs, LED to indicate flashlight battery charging.

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

Current limiting capacitor. It is designed to limit the battery charging current. Its capacity for each type of flashlight may be different. A non-polar mica capacitor is used. The operating voltage must be at least 250 volts. In the circuit it must be bypassed, as shown, with a resistor. It serves to discharge the capacitor after you remove the flashlight from the charging outlet. Otherwise, you may get an electric shock if you accidentally touch the 220 volt power 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.

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

It makes no sense to talk about the other elements; everything should be clear anyway.

I would like to draw your attention to the main points of repairing an LED flashlight. Let's look at the main faults and how to fix them.

1. The flashlight stopped shining. There aren't 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 jump in current will occur and one or more diodes of the rectifier bridge may be broken. And behind them, the capacitor may not be able to withstand it and will short out. The voltage on the battery will increase sharply and the LEDs will fail. So, under no circumstances turn on the flashlight while charging unless you want to throw it away.

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

3. The flashlight discharges very quickly. If your flashlight is “experienced”, then most likely the battery has reached its service life. If you actively use the flashlight, then after one year of use the battery will no longer last.

Problem 1: The LED flashlight does not turn on or flickers when working

As a rule, this is the cause of poor contact. The easiest way to treat it is to tighten all the threads tightly.
If the flashlight doesn't work at all, start by checking the battery. It may be discharged or damaged.

Unscrew the back cover of the flashlight and use a screwdriver to connect the housing to the negative terminal 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 by a loose clamping ring.
To fix this problem, just find round pliers with thin tips or thin scissors that need to be inserted into the holes, as in the photo, and turned clockwise.

If the ring moves, the problem is fixed. If the ring stays in place, then the problem lies in the contact of the button module with the body. Unscrew the clamping ring counterclockwise and pull the button module out.
Poor contact often occurs due to oxidation of the aluminum surface of the ring or border on the printed circuit board (indicated by arrows)

Simply wipe these surfaces with alcohol and functionality will be restored.

Button modules are different. Some have contact through the printed circuit board, others have contact through the side petals to the flashlight body.
Just bend this petal to the side so that the contact is tighter.
Alternatively, you can make a solder from tin so that the surface is thicker and the contact is pressed better.
All LED lights are basically the same

The plus goes through the positive contact of the battery to the center of the LED module.
The negative goes through the body and is closed with a button.

It would be a good idea to check the tightness of the LED module inside the housing. This is also a common problem with LED lights.

Using round nose pliers or pliers, rotate the module clockwise until it stops. Be careful, it is easy to damage the LED at this point.
These actions should be quite enough to restore the functionality of the LED flashlight.

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

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

Most likely the driver has failed.
The driver is an electronic circuit on transistors that controls the flashlight modes and is also responsible for a constant voltage level, regardless of battery discharge.

You need to unsolder the burnt driver and solder in a new driver, or connect the LED directly to the battery. In this case, you lose all modes and are left only with the maximum one.

Sometimes (much less often) the LED fails.
You can check this very simply. Apply a voltage of 4.2 V/ to the contact pads of the LED. The main thing is not to confuse the polarity. If the LED lights up brightly, then the driver has failed, if vice versa, then you need to order a new LED.

Unscrew the module with the LED from the housing.
Modules vary, but as a rule, they are made of copper or brass and

The weakest point of such flashlights is the button. Its contacts oxidize, as a result of which the flashlight begins to shine dimly, and then may stop turning on altogether.
The first sign is that a flashlight with a normal battery shines dimly, 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 and cut off one strand.
2. We wind the wires onto the spring.
3. We bend the wire so that the battery does not break it. The wire should protrude slightly
above the twisting part of the flashlight.
4. Twist tightly. We break off (tear off) the excess wire.
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, the button is no longer available for such repairs, so
Turning on and off the flashlight is done by turning the head part.
My Chinese guy worked like this for a couple of months. If you need to change the battery, the back of the flashlight
should not be touched. We turn our heads away.

RESTORING THE OPERATION OF THE BUTTON.

1. Use a 2 mm drill to make a couple of holes to a depth of 2-3 mm.
2. Now you can use tweezers to unscrew the housing with the button.
3. Remove the button.
4. The button is assembled without glue or latches, so it can be easily disassembled with a stationery knife.
The photo shows that the moving contact has oxidized (a round thing in the center that looks like a button).
You can clean it with an eraser or fine sandpaper and put the button back together, but I decided to additionally tin both this part and the fixed contacts.

1. Clean with fine sandpaper.
2. Apply a thin layer to the areas marked in red. We wipe off the flux with alcohol,
assembling the button.
3. To increase reliability, I soldered a spring to the bottom contact of the button.
4. Putting everything back together.
After repair, the button works perfectly. Of course, tin also oxidizes, but since tin is a fairly soft metal, I hope that the oxide film will be
easy to break down. It’s not for nothing that the central contact on light bulbs is made of tin.

IMPROVING FOCUS.

My Chinese friend had a very vague idea of what a “hotspot” was, so I decided to enlighten him.
Unscrew the head part.

1. There is a small hole in the board (arrow). Use an awl to twist out the filling.
At the same time, lightly press your finger on the glass from the outside. This makes it easier to unscrew.
2. Remove the reflector.
3. Take ordinary office paper and punch 6-8 holes with an office hole punch.
The diameter of the holes in the hole punch matches perfectly with the diameter of the LED.
Cut out 6-8 paper washers.
4. Place the washers on the LED and press it with the reflector.
Here you will have to experiment with the number of washers. I improved the focusing of a couple of flashlights in this way; the number of washers was in the range of 4-6. The current patient required 6 of them.

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

The Chinese save on everything. A couple of extra details will increase the cost, so they don’t install 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:
inductor and a 3-leg IC similar to a transistor). But they save on the part marked in red. I added a capacitor and a pair of 1n4148 diodes in parallel (I didn't have any shots). The brightness of the LED increased by 10-15 percent.

1. This is what the LED looks like in similar Chinese ones. From the side you can see that there are thick and thin legs inside. The thin leg is a plus. You need to be guided by this sign, because the colors of the wires can be completely unpredictable.
2. This is what the board looks like with the LED soldered to it (on the back side). Green color indicates foil. The wires coming from the driver are soldered to the legs of the LED.
3. Using a sharp knife or a triangular file, cut the foil on the positive side of the LED.
We sand the entire board to remove the varnish.
4. Solder the diodes and capacitor. I took the diodes from a broken computer power supply, and soldered the tantalum capacitor from some burnt-out hard drive.
The positive wire now needs to be soldered to the pad with the 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 minimum mode.

Many people have various Chinese lanterns that run on a single battery. Something like this:

Unfortunately, they are very short-lived. I will tell you further about how to bring a flashlight back to life and about some simple modifications that can improve such flashlights.

The weakest point of such flashlights is the button. Its contacts oxidize, as a result of which the flashlight begins to shine dimly, and then may stop turning on altogether.
The first sign is that a flashlight with a normal battery shines dimly, 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 and cut off one strand.
2. We wind the wires onto the spring.
3. We bend the wire so that the battery does not break it. The wire should protrude slightly
above the twisting part of the flashlight.
4. Twist tightly. We break off (tear off) the excess wire.
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, the button is no longer available for such repairs, so
Turning the flashlight on and off is done by turning the head part.
My Chinese guy worked like this for a couple of months. If you need to change the battery, the back of the flashlight
should not be touched. We turn our heads away.

RESTORING THE OPERATION OF THE BUTTON.

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

1. Use a 2 mm drill to make a couple of holes to a depth of 2-3 mm.
2. Now you can use tweezers to unscrew the housing with the button.
3. Remove the button.
4. The button is assembled without glue or latches, so it can be easily disassembled with a stationery knife.
The photo shows that the moving contact has oxidized (a round thing in the center that looks like a button).
You can clean it with an eraser or fine sandpaper and put the button back together, but I decided to additionally tin both this part and the fixed contacts.

1. Clean with fine sandpaper.
2. Apply a thin layer to the areas marked in red. We wipe off the flux with alcohol,
assembling the button.
3. To increase reliability, I soldered a spring to the bottom contact of the button.
4. Putting everything back together.
After repair, the button works perfectly. Of course, tin also oxidizes, but since tin is a fairly soft metal, I hope that the oxide film will be
easy to break down. It’s not for nothing that the central contact on light bulbs is made of tin.

IMPROVING FOCUS.

My Chinese friend had a very vague idea of what a “hotspot” was, so I decided to enlighten him.
Unscrew the head part.

1. There is a small hole in the board (arrow). Use an awl to twist out the filling.
At the same time, lightly press your finger on the glass from the outside. This makes it easier to unscrew.
2. Remove the reflector.
3. Take ordinary office paper and punch 6-8 holes with an office hole punch.
The diameter of the holes in the hole punch matches perfectly with the diameter of the LED.
Cut out 6-8 paper washers.
4. Place the washers on the LED and press it with the reflector.
Here you will have to experiment with the number of washers. I improved the focusing of a couple of flashlights in this way; the number of washers was in the range of 4-6. The current patient required 6 of them.
What happened in the end:

On the left is our Chinese, on the right is Fenix LD 10 (at minimum).
The result is quite pleasant. The hotspot became pronounced and uniform.

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

The Chinese save on everything. A couple of extra details will increase the cost, so they don’t install 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:
inductor and a 3-leg IC similar to a transistor). But they save money on the part marked in red. I added a capacitor and a pair of 1n4148 diodes in parallel (I didn't have any shots). The brightness of the LED increased by 10-15 percent.

As a result, the flashlight produces (by eye) 10-12 lumens (see photo with hotspots),
judging by the Phoenix, which produces 9 lumens in 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 batteries, so
With the battery discharged to 1 volt, my Fenix LD 10 simply does not turn on. At all.
I took a dead alkaline battery that had expired in the computer mouse. The multimeter showed that it had dropped to 1.12v. The mouse no longer worked on it, Fenix, as I said, did not start. But the Chinese one works!

On the left is the Chinese, on the right is the Fenix LD 10 at minimum (9 lumens). Unfortunately, the white balance is off.
The phoenix has a temperature of 4200K. The Chinese is blue, but not as bad as in the photo.
Just for fun, I tried to finish off the battery. At this brightness level (5-6 lumens by eye), the flashlight worked for about 3 hours. The brightness is quite enough to illuminate your feet in a dark entrance/forest/basement. Then for another 2 hours the brightness decreased to the “firefly” level. Agree, 3-4 hours with acceptable light can solve a lot.
For this, let me take my leave.
Stari4ok.

ZY The article is not a copy-paste. Made in I, especially for “NOT PROPAD”!