LED lamp device. We disassemble the EKF lamp of the FLL-A series. LED lamp circuit: simple driver device Wiring diagram for a 220 volt LED lamp

The device of 220v LED lamps in many cases varies depending on the design features laid down by the manufacturer.

Nevertheless, knowledge of the main types of the device allows you to independently determine the cause of the malfunction of the lighting device, as well as perform some simple repairs with your own hands.

Consider which LEDs are used in lamps. Currently, there are a huge number of subspecies and groups that are types of LED lighting fixtures, but the most basic types include the following:

• Low current super bright source and smd LED. Such options are very often used as indicators. An LED can be assembled on a single chip without using a lens, or on multiple chips using a common lens.
• The COB module is square or linear with a white glow, which makes this type popular in spotlights and lanterns used in street lighting.
• Filament is a rod version, reaching a quarter of a meter in length and consisting of a very large number of crystals. The filament type is especially popular in the production of 220V filament fixtures.
• Display type OLED-light emitting diodes, characterized by a very characteristic thin-film and organic structure.

No less popular are LEDs, which are used in the manufacture of remote control, as well as lamps for medical or cosmetic purposes.

Thus, regardless of the typical features, the main components of the LED lamp are represented by the base part, the built-in driver or current stabilizer, the diffuser housing, as well as directly by light emitting diodes.

Assembly methods

To date, several methods of assembling lighting elements are practiced, thanks to which a certain classification of modern LEDs has been created.

DIP

The Dual In-line Package option is an interesting, in terms of design, but outdated look, characterized by the following LED sizes:

• 0.3 cm;
• 0.5 cm;
• 0.8 cm;
• 1.0 cm.

In addition to the size of the bulb, semiconductors differ markedly in color and materials that are used for manufacturing, as well as the shape of the chip. The main advantages of this type of LEDs include low heat and decent brightness.

Dual In-line Paskage are available in both single color and RGB versions, and most often have a very characteristic cylindrical shape, and have a built-in convex lens.

"Piranha"

LEDs belonging to this group are characterized by the best light qualities in terms of luminous flux. The design feature is represented by a rectangular shape and the presence of four special pin-outs. Available in red, green, blue and white.

One of the main differences is the possibility of a more “rigid” fixation on the board, and the very high thermal conductivity is due to the lead substrate.

LED Lamp Piranha Chameleon (RGB)

The presence of lead casts doubt on the safety of operation, but a wide operating temperature range allows the use of high input powers, which is the reason for its wide popularity.

SMD technology

SMD LEDs, also known as Surface Mounting Devices or “surface-mounted devices”, have a power of 0.01-0.2W.

A feature of SMD LEDs is the presence of one, two or three modern crystals on ceramic rectangular bases.

SMD LEDs are individually coated with a high-quality phosphor layer. The contact pads and base of the circuit board are directly connected using standard solder.

The disadvantages of such modern technology include low maintainability of the structure, as well as the need to completely replace the board with all the LEDs when one of them fails.

COB technology

The modern manufacturing technology of LED lamps, called Chir On Board, is characterized by fixing crystals on a board without a case and a ceramic substrate, and coating with a common phosphor. The main advantage of any COB illuminators is the minimum glow area with increased power levels.

COB Type LED Bulb

The high density of placement and the presence of a common coating with a layer of phosphor guarantees the most uniform glow of the lighting device.

Among economical lamps, fluorescent lamps were first widely used, but now more and more preference is given to LED lamps. - this information will be useful for those who decide to replace light bulbs.

Read about how to choose and install a transformer for an LED strip.

Types and methods of connecting a dimmer for LED lamps are described.

LED lamp device

Depending on the purpose of the lighting device and the characteristics of the manufacturer's production lines, the device of the LED light bulb may have some rather noticeable differences that should be considered when choosing.

LED lamp device

branded products

The design features of 220V LED lamps, which are produced by world-famous manufacturers, are the presence of the following mandatory components:

• light scattering hemisphere;
• chips;
• aluminum printed circuit board with a paste of sufficient thermal conductivity, which allows you to adjust the performance of the chips;
• radiators based on anodized aluminum alloy;
• a driver having a galvanically isolated modulator circuit;
• polymer base of the base in the form of polyethylene terephthalate;
• base part with nickel coating.

It should be noted that the driver has an increased density of mounting such parts as a pulse-type transformer, microcircuits and polar capacitors, as well as various planar elements.

low quality chinese light bulbs

It is the insufficiently high quality and the lack of a number of elements that explain the low cost of LED light sources produced by a Chinese manufacturer:

• lack of a radiator;
• lack of a driver;
• the presence of a simple supply unit in the form of a non-polar capacitor;
• lack of reliable stabilization of the output current.

The power supply unit is installed in the central part of the board with light diodes. On one side there is a diode bridge and resistors, and on the other side there is a pair of capacitors.

The cooling process in Chinese light sources is carried out through inefficient pinholes in the case, which becomes the main reason for the frequent burnout of crystals.

Filament lamp

The design feature of the "filament lamp" is the presence of the main components, represented by:

• LED rods;
• glass flask;
• metal plinth;
• driver board.

As an addition, the presence of the base of the basement can be considered.

Thus, an LED filament can be thought of as a rectangular or round glass rod with miniature LED chips.

Applying a thick silicone layer of yellow phosphor to each element helps to prevent the passage of ultraviolet rays, and also allows you to get the most uniform dispersion of the light flux.

Switching scheme

As practice shows, despite the rather high cost, the total consumption of electrical energy by semiconductor lighting devices is significantly lower than that of standard incandescent bulbs, and the average service life, on the contrary, is about five times longer.

LED Lamp Wiring Diagram

The circuit for switching on such a light source is very simple. The LED lamp operates under 220V supply conditions, as a result of the conversion by the driver to the operating values ​​of the input signal, causing the glow.

Related video

The 220 V LED lamp circuit allows you not only to understand the principle of operation of this device, but also to make it yourself. Attempts to make bulbs of the e27 type on their own are due to the fact that it is far from always possible to purchase a lighting device with the necessary characteristics. And just those who like to "tinker" with electronics are not averse to trying something new.

• Important nuances
• Scheme
  • With diode bridge
    • LEDs
  • Resistor

Important nuances

There are many systems according to which LED lighting operates on AC 220 volts. Moreover, all of them, together with the ballast scheme, are designed to solve three main tasks.

• Convert the alternating current of the network 220v into a pulsating current;
• Align the pulsating current, making it constant;
• Achieve a current strength of 12 volts.

If you want to assemble a device that is powered by a regular network, you will have to deal with some basic problems in order to connect.

1. Where to place the circuits and directly the device itself based on LEDs. After all, diodes will need their own place.
2. How can I isolate the LED lighting device.
3. How to provide the necessary heat exchange to connect the lamp.

Of course, you can safely purchase the popular e27 lamp. This diode device is one of the most popular on the market, it works perfectly from a regular household network.

Scheme

To assemble a circuit and get, based on it, an LED device for lighting a house from a 220 Volt power supply, you will need:

• Align alternating current;
• Achieve the required power parameters;
• Provide the necessary resistance.

All this can be done in two ways. There are two main variations.

To save on electricity bills, our readers recommend the Electricity Saving Box. Monthly payments will be 30-50% less than they were before using the saver. It removes the reactive component from the network, as a result of which the load and, as a result, the current consumption are reduced. Electrical appliances consume less electricity, reducing the cost of its payment.

1. Scheme based on a diode bridge.
2. Resistor circuit where a clear number of LEDs is used.

They are quite simple, because the device is assembled without any problems.

With diode bridge

• The design of the diode bridge includes 4 multidirectional LEDs;
• The task of the bridge is to make a pulsating current from a sinusoidal alternating one;
• Half-waves are carried out through 2 diodes, due to which the minus loses polarity;
• In the circuit, it is necessary to connect the positive capacitor on the side of the AC source in front of the diode bridge;
• Before the minus, a resistance with a nominal value of 100 ohms is set;
• The parallel bridge behind it will need to attach another capacitor. It will smooth out voltage drops;
• With elementary skills in working with a soldering iron, it will not be difficult for a novice master to assemble such a circuit.

LEDs

• You can use a standard LED board borrowed from a non-functioning lamp;
• Before assembly, be sure to check each element for operability. To do this, use a 12 volt battery;
• If there are non-working components, their contacts must be unsoldered and new ones installed;
• Pay special attention to the legs of the cathode and anode. They should be connected in series;
• If you are just changing a few parts of an old lamp, it is enough to replace non-working elements with functioning ones by installing them in their old places;
• If you decide to assemble the device yourself, remember an important rule - LED lamps are connected in series with 10 units, after which the circuits should be connected in parallel.

As a result, your diagram should look like this.

1. 10 LEDs go in one row. Then the legs of the anode and cathode are soldered so that 9 joints and 1 tail are obtained along the edges, which are in a free position.
2. All resulting circuits are connected to wires. The ends of the cathode go to one, and the ends of the anode go to the other.
3. Remember that the cathode is positive and is connected to negative. The anode is negative and must be connected to the positive.
4. Make sure that the ends soldered together do not touch the other ends in the diagram. If this situation happens, the circuit will burn out, a short circuit will occur.

Resistor

The electronic ballast circuit can provide the required power for LED lamps powered by 220V.

Creating a ballast and connecting here is not difficult, therefore a relatively newcomer to the field of electronics can cope with a similar task.

• The resistor circuit for LEDs consists of a pair of 12K resistors and a pair of strings;
• The chains consist of the same number of LED elements;
• LED elements are soldered in series and have different directions;
• On the R1 side, one strip of LED elements is soldered with the cathode, and the second strip with the anode;
• The second tap to R2 is reversed;
• Due to this scheme, the glow of LED lamps is soft. This is due to the fact that the LED elements start to burn in turn, because the pulsating flashes are practically invisible to the human eye;
• A similar LED device, powered by 220 volts, can be used to illuminate the desktop, highlight certain areas. Therefore, they can replace traditional lamps, obtaining a light of the same efficiency or even a higher quality glow;
• Practice shows that the resistor circuit of the LED device shows itself most effectively when using at least 20 LEDs. And it is even more preferable to use 40 elements;
• Due to so many LEDs and circuit features, you get high-quality lighting. There are absolutely no problems with assembling the circuit, everything is very simple;
• The only nuances of the circuit with 20-40 LEDs is that soldering must be done very carefully so as not to damage adjacent contacts. Plus, to collect all this in a single compact case is another task.

Due to low power consumption, theoretical durability and lower prices, incandescent and energy-saving lamps are rapidly replacing. But, despite the declared service life of up to 25 years, they often burn out without even having served the warranty period.

Unlike incandescent lamps, 90% of burned-out LED lamps can be successfully repaired with your own hands, even without special training. The presented examples will help you to repair failed LED lamps.

Before undertaking the repair of an LED lamp, you need to present its device. Regardless of the appearance and type of LEDs used, all LED lamps, including filament bulbs, are arranged in the same way. If you remove the walls of the lamp housing, then inside you can see the driver, which is a printed circuit board with radio elements installed on it.

Any LED lamp is arranged and works as follows. The supply voltage from the contacts of the electric cartridge is supplied to the terminals of the base. Two wires are soldered to it, through which voltage is applied to the input of the driver. From the driver, a DC supply voltage is supplied to the board on which the LEDs are soldered.

The driver is an electronic unit - a current generator that converts the mains voltage into the current required to light the LEDs.

Sometimes, to scatter light or protect against human contact with unprotected conductors of a board with LEDs, it is covered with a diffusing protective glass.

About filament lamps

In appearance, a filament lamp is similar to an incandescent lamp. The device of filament lamps differs from LED lamps in that they do not use a board with LEDs as light emitters, but a glass sealed bulb filled with gas, in which one or more filament rods are placed. The driver is located in the base.

The filament rod is a glass or sapphire tube with a diameter of about 2 mm and a length of about 30 mm, on which 28 miniature LEDs coated in series with a phosphor are fixed and connected. One filament consumes about 1 W of power. My operating experience shows that filament lamps are much more reliable than those made on the basis of SMD LEDs. I think over time they will replace all other artificial light sources.

Examples of repair of LED lamps

Attention, the electrical circuits of the LED lamp drivers are galvanically connected to the phase of the electrical network and therefore extreme care must be taken. Touching an unprotected part of the human body to bare parts of a circuit connected to an electrical network can cause serious damage to health, up to cardiac arrest.

LED Lamp Repair
ASD LED-A60, 11 W on SM2082 chip

Currently, powerful LED bulbs have appeared, the drivers of which are assembled on microcircuits of the SM2082 type. One of them worked less than a year and got me to repair. The light bulb flickered randomly and came on again. When tapped on it, it responded with light or extinction. It became obvious that the problem was a bad connection.

To get to the electronic part of the lamp, you need to use a knife to pick up the diffusing glass at the point of contact with the body. Sometimes it is difficult to separate the glass, since silicone is applied to the retaining ring when it is seated.

After removing the light-scattering glass, access to the LEDs and the microcircuit - the current generator SM2082 was opened. In this lamp, one part of the driver was mounted on an aluminum printed circuit board of LEDs, and the second on a separate one.

External inspection did not reveal defective rations or broken tracks. I had to remove the board with LEDs. To do this, the silicone was first cut off and the board was pushed over the edge with a screwdriver blade.

To get to the driver located in the lamp housing, I had to unsolder it, heating two contacts at the same time with a soldering iron and moving it to the right.

On one side of the driver PCB, only an electrolytic capacitor with a capacity of 6.8 microfarads for a voltage of 400 V was installed.

On the reverse side of the driver board, a diode bridge and two series-connected resistors with a nominal value of 510 kOhm were installed.

In order to figure out which of the boards was losing contact, they had to be connected, observing the polarity, using two wires. After tapping the boards with a screwdriver handle, it became obvious that the fault lies in the board with the capacitor or in the contacts of the wires coming from the LED lamp base.

Since soldering did not arouse suspicion, I first checked the reliability of the contact in the central terminal of the base. It is easily removed by prying it over the edge with a knife blade. But the contact was reliable. Just in case, I tinned the wire with solder.

It is difficult to remove the screw part of the base, so I decided to solder the solder wires suitable from the base with a soldering iron. When touching one of the rations, the wire was exposed. Found "cold" soldering. Since there was no way to get to strip the wire, I had to lubricate it with the FIM active flux, and then solder it again.

After assembly, the LED lamp emitted light steadily, despite being hit with a screwdriver handle. Checking the luminous flux for pulsations showed that they are significant at a frequency of 100 Hz. Such a LED lamp can only be installed in luminaires for general lighting.

Driver circuit diagram
LED lamp ASD LED-A60 on the chip SM2082

The electrical circuit of the ASD LED-A60 lamp, thanks to the use of a specialized SM2082 microcircuit in the driver to stabilize the current, turned out to be quite simple.

The driver circuit works as follows. The AC supply voltage is fed through fuse F to the rectifier diode bridge assembled on the MB6S microassembly. The electrolytic capacitor C1 smooths out the ripple, and R1 serves to discharge it when the power is turned off.

From the positive terminal of the capacitor, the supply voltage is applied directly to the LEDs connected in series. From the output of the last LED, the voltage is applied to the input (pin 1) of the SM2082 microcircuit, the current in the microcircuit stabilizes and then from its output (pin 2) it goes to the negative terminal of the capacitor C1.

Resistor R2 sets the amount of current flowing through the LEDs HL. The amount of current is inversely proportional to its nominal value. If the value of the resistor is reduced, then the current will increase, if the value is increased, then the current will decrease. The SM2082 chip allows you to adjust the current value from 5 to 60 mA with a resistor.

LED Lamp Repair
ASD LED-A60, 11W, 220V, E27

Another LED lamp ASD LED-A60, similar in appearance and with the same technical characteristics as the repaired one, got into repair.

When turned on, the lamp lit up for a moment and then did not shine. This behavior of LED lamps is usually associated with a driver malfunction. Therefore, I immediately began to disassemble the lamp.

The diffusing glass was removed with great difficulty, since it was heavily lubricated with silicone along the entire line of contact with the case, despite the presence of a retainer. To separate the glass, I had to look for a pliable place along the entire line of contact with the body with a knife, but still there was a crack in the body.

To gain access to the lamp driver, the next step was to remove the LED printed circuit board, which was pressed into the aluminum insert along the contour. Despite the fact that the board was aluminum, and it was possible to remove it without fear of cracking, all attempts were unsuccessful. The pay was held tight.

It also failed to remove the board together with the aluminum insert, since it fit snugly against the case and was planted on silicone by the outer surface.

I decided to try to remove the driver board from the side of the base. To do this, first, a knife was pulled out of the base, and the central contact was removed. To remove the threaded part of the base, it was necessary to slightly bend its upper shoulder so that the punching points disengaged from the base.

The driver became accessible and freely extended to a certain position, but it was not possible to completely remove it, although the conductors from the LED board were soldered.

There was a hole in the center of the board with the LEDs. I decided to try to remove the driver board by hitting its end through a metal rod threaded through this hole. The board advanced a few centimeters and rested against something. After further blows, the lamp body cracked along the ring and the board with the base of the base separated.

As it turned out, the board had an extension, which rested against the lamp body with its hangers. It looks like the board was shaped in such a way to restrict movement, although it was enough to fix it with a drop of silicone. Then the driver would be removed from either side of the lamp.

The voltage of 220 V from the lamp base through the resistor - fuse FU is fed to the MB6F rectifier bridge and after it is smoothed by an electrolytic capacitor. Next, the voltage is supplied to the SIC9553 chip, which stabilizes the current. Resistors R20 and R80 connected in parallel between terminals 1 and 8 MS set the amount of current to supply the LEDs.

The photo shows a typical electrical circuit diagram given by the manufacturer of the SIC9553 chip in the Chinese datasheet.

This photo shows the appearance of the LED lamp driver from the installation side of the output elements. Since space allowed, to reduce the ripple coefficient of the light flux, the capacitor at the output of the driver was soldered to 6.8 microfarads instead of 4.7 microfarads.

If you have to remove the drivers from the body of this lamp model and you cannot remove the LED board, then you can use a jigsaw to cut the lamp body in a circle just above the screw part of the base.

In the end, all my efforts to extract the driver turned out to be useful only for knowing the device of the LED lamp. The driver was correct.

The flash of the LEDs at the moment of switching on was caused by a breakdown in the crystal of one of them as a result of a voltage surge when the driver was started, which misled me. We had to ring the LEDs first.

An attempt to test the LEDs with a multimeter did not lead to success. The LEDs didn't light up. It turned out that two series-connected light-emitting crystals are installed in one case, and in order for the LED to start flowing current, it is necessary to apply a voltage of 8 V to it.

A multimeter or tester, switched on in the resistance measurement mode, outputs a voltage in the range of 3-4 V. I had to check the LEDs using a power supply, supplying 12 V to each LED through a 1 kΩ current-limiting resistor.

There was no replacement LED available, so the pads were closed with a drop of solder instead. It is safe for the driver to work, and the power of the LED lamp will decrease by only 0.7 W, which is almost imperceptible.

After the repair of the electrical part of the LED lamp, the cracked housing was glued together with Moment's quick-drying super glue, the seams were smoothed by melting the plastic with a soldering iron and leveled with sandpaper.

For interest, I performed some measurements and calculations. The current flowing through the LEDs was 58 mA, the voltage was 8 V. Therefore, the power supplied to one LED is 0.46 W. With 16 LEDs, it turns out 7.36 watts, instead of the declared 11 watts. Perhaps the manufacturer indicates the total power consumption of the lamp, taking into account losses in the driver.

The service life of the LED lamp ASD LED-A60, 11 W, 220 V, E27, declared by the manufacturer, is very doubtful to me. In a small volume of the plastic lamp housing, with low thermal conductivity, significant power is released - 11 watts. As a result, the LEDs and the driver operate at the maximum allowable temperature, which leads to accelerated degradation of their crystals and, as a result, to a sharp decrease in their MTBF.

LED Lamp Repair
LED smd B35 827 ERA, 7 W on BP2831A chip

A friend shared with me that he bought five light bulbs as in the photo below, and all of them stopped working after a month. He managed to throw away three of them, and, at my request, he brought two for repair.

The light bulb worked, but instead of a bright light, it emitted a flickering weak light at a frequency of several times per second. I immediately assumed that the electrolytic capacitor was swollen, usually if it fails, the lamp begins to emit light, like a stroboscope.

The light-scattering glass was removed easily, it was not glued. It was fixed by a slot on its rim and a protrusion in the lamp body.

The driver was fixed with two solders to a printed circuit board with LEDs, as in one of the lamps described above.

A typical driver circuit on a BP2831A chip taken from the datasheet is shown in the photo. The driver board was removed and all simple radio elements were checked, everything turned out to be in good order. I had to check the LEDs.

The LEDs in the lamp were installed of an unknown type with two crystals in the case and the inspection did not reveal any defects. Using the method of serially connecting the leads of each of the LEDs to each other, he quickly identified the faulty one and replaced it with a drop of solder, as in the photo.

The lamp worked for a week and again got into repair. Shorted the next LED. A week later, I had to short-circuit another LED, and after the fourth I threw out the bulb, because I was tired of repairing it.

The reason for the failure of light bulbs of this design is obvious. LEDs overheat due to insufficient heat sink surface, and their life is reduced to hundreds of hours.

Why is it permissible to close the terminals of burned-out LEDs in LED lamps

The LED lamp driver, unlike the constant voltage power supply, outputs a stabilized current value, not voltage. Therefore, regardless of the load resistance within the given limits, the current will always be constant and, therefore, the voltage drop across each of the LEDs will remain the same.

Therefore, with a decrease in the number of series-connected LEDs in the circuit, the voltage at the output of the driver will also decrease proportionally.

For example, if 50 LEDs are connected in series to the driver, and a voltage of 3 V drops across each of them, then the voltage at the output of the driver was 150 V, and if 5 of them were shorted, the voltage would drop to 135 V, and the current would not change.

But the coefficient of performance (COP) of a driver assembled according to such a scheme will be low and power losses will be more than 50%. For example, for an MR-16-2835-F27 LED bulb, you will need a 6.1 kΩ resistor with a power of 4 watts. It turns out that the driver on the resistor will consume power that exceeds the power consumption of the LEDs and it will be unacceptable to place it in a small LED lamp housing, due to the release of more heat.

But if there is no other way to repair the LED lamp and it is very necessary, then the driver on the resistor can be placed in a separate case, all the same, the power consumption of such an LED lamp will be four times less than incandescent lamps. At the same time, it should be noted that the more LEDs connected in series in the light bulb, the higher the efficiency will be. With 80 serially connected SMD3528 LEDs, you will need an 800 ohm resistor with a power of only 0.5 watts. Capacitor C1 will need to be increased to 4.7 µF.

Finding faulty LEDs

After removing the protective glass, it becomes possible to check the LEDs without peeling off the printed circuit board. First of all, a careful inspection of each LED is carried out. If even the smallest black dot is detected, not to mention the blackening of the entire surface of the LED, then it is definitely faulty.

When examining the appearance of the LEDs, you need to carefully examine the quality of the rations of their conclusions. In one of the light bulbs being repaired, four LEDs were poorly soldered at once.

The photo shows a light bulb that had very small black dots on four LEDs. I immediately marked the faulty LEDs with crosses so that they could be clearly seen.

Faulty LEDs may or may not change appearance. Therefore, it is necessary to check each LED with a multimeter or arrow tester included in the resistance measurement mode.

There are LED lamps in which standard LEDs are installed in appearance, in the case of which two crystals connected in series are mounted at once. For example, lamps of the ASD LED-A60 series. To make such LEDs ring, it is necessary to apply a voltage of more than 6 V to its terminals, and any multimeter gives out no more than 4 V. Therefore, such LEDs can only be checked by applying a voltage of more than 6 (9-12) V through a 1 kΩ resistor from the power source. .

The LED is checked, like a conventional diode, in one direction the resistance should be equal to tens of megaohms, and if you change the probes in places (this changes the polarity of the voltage supply to the LED), then it is small, while the LED may glow dimly.

When checking and replacing LEDs, the lamp must be fixed. To do this, you can use a suitable size round jar.

You can check the health of the LED without an additional DC source. But such a verification method is possible if the light bulb driver is working. To do this, it is necessary to apply a supply voltage to the LED lamp base and short the leads of each LED in series with each other with a wire jumper or, for example, metal tweezers sponges.

If suddenly all the LEDs light up, then the shorted one is definitely faulty. This method is useful if only one LED out of all in the circuit is faulty. With this method of verification, it must be taken into account that if the driver does not provide galvanic isolation from the mains, as, for example, in the diagrams above, then touching the LED solderings with your hand is unsafe.

If one or even several LEDs turned out to be faulty and there is nothing to replace them with, then you can simply short-circuit the pads to which the LEDs were soldered. The light bulb will work with the same success, only the luminous flux will decrease slightly.

Other malfunctions of LED lamps

If the check of the LEDs showed their serviceability, then it means that the reason for the inoperability of the light bulb lies in the driver or in the places where the current-carrying conductors are soldered.

For example, in this light bulb, a cold soldered conductor was found that supplies voltage to the printed circuit board. The soot released due to poor soldering even settled on the conductive tracks of the printed circuit board. The soot was easily removed by wiping with a rag soaked in alcohol. The wire was soldered, stripped, tinned and re-soldered into the board. Good luck with this lamp.

Of the ten failed light bulbs, only one had a faulty driver, the diode bridge fell apart. The repair of the driver consisted in replacing the diode bridge with four IN4007 diodes, designed for a reverse voltage of 1000 V and a current of 1 A.

Soldering SMD LEDs

To replace a faulty LED, it must be desoldered without damaging the printed conductors. From the donor board, you also need to solder the replacement LED without damage.

It is almost impossible to solder SMD LEDs with a simple soldering iron without damaging their case. But if you use a special tip for a soldering iron or put on a standard tip a nozzle made of copper wire, then the problem is easily solved.

The LEDs have polarity and when replacing, you need to correctly install it on the printed circuit board. Typically, printed conductors follow the shape of the leads on the LED. Therefore, you can make a mistake only if you are inattentive. To solder the LED, it is enough to install it on a printed circuit board and heat its ends with contact pads with a soldering iron with a power of 10-15 W.

If the LED burned out on coal, and the printed circuit board under it was charred, then before installing a new LED, it is imperative to clean this place of the printed circuit board from burning, since it is a current conductor. When cleaning, you may find that the pads for soldering the LED are burned or peeled off.

In such a case, the LED can be installed by soldering it to adjacent LEDs if the printed tracks lead to them. To do this, you can take a piece of thin wire, bend it in half or three, depending on the distance between the LEDs, tin and solder to them.

Repair LED lamp series "LL-CORN" (corn lamp)
E27 4.6W 36x5050SMD

The device of the lamp, which is popularly called the corn lamp, shown in the photo below, differs from the lamp described above, therefore the repair technology is different.

The design of LED SMD lamps of this type is very convenient for repair, as there is access for LED continuity and replacement without disassembling the lamp housing. True, I still dismantled the light bulb for interest in order to study its device.

Checking the LEDs of the LED corn lamp does not differ from the technology described above, but it must be taken into account that three LEDs are placed in the SMD5050 LED housing at once, usually connected in parallel (three dark dots of crystals are visible on the yellow circle), and when checking, all three should glow.

A defective LED can be replaced with a new one or shorted with a jumper. This will not affect the reliability of the lamp, only imperceptibly to the eye, the luminous flux will decrease slightly.

The driver of this lamp is assembled according to the simplest scheme, without an isolation transformer, so touching the LED terminals when the lamp is on is unacceptable. Lamps of this design are unacceptable to be installed in fixtures that can be reached by children.

If all the LEDs are working, then the driver is faulty, and in order to get to it, the lamp will have to be disassembled.

To do this, remove the bezel from the side opposite the base. With a small screwdriver or a knife blade, you need to try in a circle to find a weak spot where the bezel is glued the worst. If the rim succumbed, then working with the tool as a lever, the rim will easily move away around the entire perimeter.

The driver was assembled according to the electrical circuit, like the MR-16 lamp, only C1 had a capacity of 1 µF, and C2 - 4.7 µF. Due to the fact that the wires from the driver to the lamp base were long, the driver was easily pulled out of the lamp housing. After studying his circuit, the driver was inserted back into the case, and the bezel was glued in place with Moment transparent glue. The failed LED was replaced with a good one.

Repair of LED lamp "LL-CORN" (corn lamp)
E27 12W 80x5050SMD

When repairing a more powerful lamp, 12 W, there were no failed LEDs of the same design, and in order to get to the drivers, I had to open the lamp using the technology described above.

This lamp gave me a surprise. The wires from the driver to the base were short, and it was impossible to remove the driver from the lamp housing for repair. I had to remove the plinth.

The base of the lamp was made of aluminium, rounded and held tight. I had to drill out the attachment points with a 1.5 mm drill. After that, the plinth, which was hooked with a knife, was easily removed.

But you can do without drilling the base, if you pry the edge of the knife around the circumference and slightly bend its upper edge. A mark should first be placed on the plinth and body so that the plinth can be easily installed in place. To securely fix the base after repairing the lamp, it will be enough to put it on the lamp body so that the punched points on the base fall into their old places. Next, push these points with a sharp object.

Two wires were connected to the thread with a clamp, and the other two were pressed into the central contact of the base. I had to cut these wires.

As expected, there were two identical drivers, feeding 43 diodes each. They were covered with heat shrink tubing and taped together. In order for the driver to be placed back into the tube, I usually carefully cut it along the printed circuit board from the side where the parts are installed.

After repair, the driver is wrapped in a tube, which is fixed with a plastic tie or wrapped with several turns of thread.

In the electrical circuit of the driver of this lamp, protection elements are already installed, C1 for protection against impulse surges and R2, R3 for protection against current surges. When checking the elements, resistors R2 were immediately found on both drivers in the open. It appears that the LED lamp was supplied with a voltage exceeding the allowable voltage. After replacing the resistors, there was no 10 Ohm at hand, and I set it to 5.1 Ohm, the lamp worked.

Repair LED lamp series "LLB" LR-EW5N-5

The appearance of this type of light bulb inspires confidence. Aluminum case, high-quality workmanship, beautiful design.

The design of the light bulb is such that it is impossible to disassemble it without the use of significant physical effort. Since the repair of any LED lamp begins with checking the health of the LEDs, the first thing that had to be done was to remove the plastic protective glass.

The glass was fixed without glue on a groove made in the radiator with a shoulder inside it. To remove the glass, you need to use the end of a screwdriver, which will pass between the radiator fins, to lean on the end of the radiator and, as a lever, lift the glass up.

Checking the LEDs with a tester showed their serviceability, therefore, the driver is faulty, and you need to get to it. The aluminum board was fastened with four screws, which I unscrewed.

But contrary to expectations, behind the board was the plane of the radiator, lubricated with heat-conducting paste. The board had to be returned to its place and continue to disassemble the lamp from the side of the base.

Due to the fact that the plastic part to which the radiator was attached was very tight, I decided to go the proven way, remove the base and remove the driver for repair through the hole that opened. I drilled out the punching points, but the base was not removed. It turned out that he was still holding on to the plastic due to the threaded connection.

I had to separate the plastic adapter from the radiator. He held, as well as protective glass. To do this, washed down with a hacksaw at the junction of the plastic with the radiator and by turning a screwdriver with a wide blade, the parts were separated from each other.

After soldering the leads from the printed circuit board of the LEDs, the driver became available for repair. The driver circuit turned out to be more complex than previous light bulbs, with an isolation transformer and a microcircuit. One of the 400 V 4.7 µF electrolytic capacitors was swollen. I had to replace it.

A check of all semiconductor elements revealed a faulty Schottky diode D4 (pictured below left). There was a SS110 Schottky diode on the board, I replaced it with the existing analog 10 BQ100 (100 V, 1 A). The forward resistance of Schottky diodes is two times less than that of ordinary diodes. The LED lamp lit up. The same problem was with the second bulb.

Repair LED lamp series "LLB" LR-EW5N-3

This LED lamp is very similar in appearance to the "LLB" LR-EW5N-5, but its design is somewhat different.

If you look closely, you can see that at the junction between the aluminum radiator and the spherical glass, unlike LR-EW5N-5, there is a ring in which the glass is fixed. To remove the protective glass, just use a small screwdriver to pick it up at the junction with the ring.

There are three nine crystal superbright LEDs on the aluminum circuit board. The board is screwed to the heatsink with three screws. Checking the LEDs showed their serviceability. Therefore, you need to repair the driver. Having experience in repairing a similar LED lamp "LLB" LR-EW5N-5, I did not unscrew the screws, but soldered the current-carrying wires coming from the driver and continued to disassemble the lamp from the side of the base.

The plastic connecting ring of the plinth with the radiator was removed with great difficulty. At the same time, part of it broke off. As it turned out, it was screwed to the radiator with three self-tapping screws. The driver is easily removed from the lamp housing.

The self-tapping screws that screw the plastic ring of the base cover the driver, and it is difficult to see them, but they are on the same axis with the thread to which the adapter part of the radiator is screwed. Therefore, a thin Phillips screwdriver can be reached.

The driver turned out to be assembled according to the transformer circuit. Checking all the elements, except for the microcircuit, did not reveal any failed ones. Therefore, the microcircuit is faulty, I did not even find a mention of its type on the Internet. The LED bulb could not be repaired, it will come in handy for spare parts. But studied her device.

Repair LED lamp series "LL" GU10-3W

It turned out, at first glance, that it was impossible to disassemble a burned-out GU10-3W LED bulb with a protective glass. An attempt to remove the glass led to its puncture. With the application of great effort, the glass cracked.

By the way, in the marking of the lamp, the letter G means that the lamp has a pin base, the letter U means that the lamp belongs to the class of energy-saving light bulbs, and the number 10 means the distance between the pins in millimeters.

LED bulbs with a GU10 base have special pins and are installed in a socket with a turn. Thanks to the expanding pins, the LED lamp is clamped in the socket and is held securely even when shaking.

In order to disassemble this LED light bulb, I had to drill a hole with a diameter of 2.5 mm in its aluminum case at the level of the surface of the printed circuit board. The drilling location must be chosen in such a way that the drill does not damage the LED when exiting. If there is no drill at hand, then the hole can be made with a thick awl.

Next, a small screwdriver is threaded into the hole and, acting like a lever, the glass is lifted. I removed the glass from two light bulbs without problems. If the test of the LEDs by the tester showed their serviceability, then the printed circuit board is removed.

After separating the board from the lamp housing, it immediately became obvious that the current-limiting resistors burned out in both one and the other lamp. The calculator determined their denomination from the bands, 160 ohms. Since the resistors burned out in LED bulbs of different batches, it is obvious that their power, judging by the size of 0.25 W, does not correspond to the power released when the driver is operating at maximum ambient temperature.

The printed circuit board of the driver was solidly filled with silicone, and I did not disconnect it from the board with LEDs. I cut off the leads of the burnt resistors at the base and soldered more powerful resistors to them, which were at hand. In one lamp, a 150 Ohm resistor with a power of 1 W was soldered, in the second two in parallel 320 Ohm with a power of 0.5 W.

In order to prevent accidental contact with the output of the resistor, to which the mains voltage is suitable with the metal body of the lamp, it was insulated with a drop of hot melt adhesive. It is waterproof and an excellent insulator. I often use it for sealing, insulating and securing electrical wires and other parts.

Hotmelt adhesive is available in the form of rods with a diameter of 7, 12, 15 and 24 mm in different colors, from transparent to black. It melts, depending on the brand, at a temperature of 80-150 °, which allows it to be melted with an electric soldering iron. It is enough to cut off a piece of the rod, place it in the right place and heat it up. The hot melt will take on the consistency of May honey. After cooling it becomes solid again. When reheated, it becomes liquid again.

After replacing the resistors, the performance of both bulbs was restored. It remains only to fix the printed circuit board and the protective glass in the lamp housing.

When repairing LED lamps, I used liquid nails "Installation" moment to fix printed circuit boards and plastic parts. The glue is odorless, adheres well to the surfaces of any materials, remains plastic after drying, has sufficient heat resistance.

It is enough to take a small amount of glue on the end of a screwdriver and apply it to the places where the parts come into contact. After 15 minutes, the glue will already hold.

When gluing the printed circuit board, in order not to wait, holding the board in place, as the wires pushed it out, fixed the board additionally at several points with hot glue.

The LED lamp began to flash like a strobe

I had to repair a pair of LED lamps with drivers assembled on a microcircuit, the malfunction of which consisted in flashing light at a frequency of about one hertz, like in a strobe.

One instance of the LED lamp began to flash immediately after being turned on for the first few seconds and then the lamp began to glow normally. Over time, the duration of the lamp flashing after switching on began to increase, and the lamp began to flash continuously. The second copy of the LED lamp began to flash continuously all of a sudden.

After disassembling the lamps, it turned out that the electrolytic capacitors installed immediately after the rectifier bridges failed in the drivers. It was easy to determine the malfunction, since the capacitor cases were swollen. But even if the capacitor looks without external defects in appearance, it is still necessary to start repairing the LED light bulb with a stroboscopic effect by replacing it.

After replacing the electrolytic capacitors with serviceable ones, the stroboscopic effect disappeared and the lamps began to shine normally.

Online calculators for determining the value of resistors
by color coding

When repairing LED lamps, it becomes necessary to determine the value of the resistor. According to the standard, the marking of modern resistors is carried out by applying colored rings to their cases. 4 colored rings are applied to simple resistors, and 5 to high-precision resistors.

Be sure to review this information before continuing to read. Any source of electricity is life-threatening if safety rules are not followed. The LED circuits described here do not have transformers and are therefore dangerous. The assembly of such circuits can be performed by people who have basic knowledge of the basics of electrical engineering.

A light emitting diode is an electronic device that emits light when a current is passed through it. LEDs are extremely efficient for their small size, they are very bright, and at the same time they consist of cheap and affordable electronic components. Many people think that LEDs are just ordinary light-emitting bulbs, but this is not at all the case.

History of LEDs

Captain Henry Joseph Round, one of the pioneers of radio, noticed an unusual glow emitted by silicon carbide during an experiment. He published his observations in General World, but he could not explain the nature of the phenomenon.

Russian scientist Oleg Losev observed the emission of light by crystals - diodes. In 1927, he published details of his work in a Russian journal and filed a patent for the "Light Relay".

In 1961, the infrared diode was created by B. Biard and G. Pitman. However, Nick Holonyak is rightfully considered the founding father of the LED. His student J. Craford in 1972 created a yellow LED. In the late 80s, thanks to the research of the Russian scientist Zh.I. Alferov, new LED materials were discovered, which gave impetus to the further development of LEDs.

In the early 70s, green LEDs were first invented, in 1971 a blue LED appeared, which was very inefficient. A breakthrough was made by Japanese scientists only in 1996, who invented a cheap blue LED.

Working principle of LED

The most common LEDs are made up of gallium (Ga), arsenic (As), and phosphorus (P). An LED is a diode PN junction that emits light instead of the heat generated by a conventional diode. When the PN junction is in forward bias, some of the holes combine with N region electrons and some of the N electrons combine with a hole from the P region. Each combination emits light or photons.

How is a 220 volt LED lamp arranged? LEDs have polarity and therefore do not work if they are connected in reverse. The easiest way to check the polarity of a common LED is to determine the thickness of the electrodes by eye. Thicker is the cathode (-). Light is emitted from the cathode. The thinner electrode is the anode (+). Some manufacturers produce LEDs in such a way that the length of the cathode and anode wires is different, the anode (+) is longer than the cathode (-). It also makes it easier to determine the polarity. Some manufacturers make both electrode wires the same length, in which case you can determine the polarity using a multimeter.

Advantages and disadvantages of LED lamps

Advantages of LED:

Disadvantages of LEDs:

• Can be unreliable for outdoor applications with large temperature swings.
• The need to additionally use heatsinks to protect semiconductors from thermal effects.

The LED is used in a wide variety of applications:

Mains powered LED lighting

But to build an LED lighting circuit, it is necessary to build special power supplies with or without regulators, transformers. As a solution, the diagram below shows the construction of a mains powered LED circuit without the use of transformers.

220 V LED lamp circuit

This circuit is powered by 220V AC as an input signal. Capacitive reactance lowers the AC voltage. An alternating current enters a capacitor whose plates are continuously being charged and discharged, and the associated currents are always flowing in and out of the plates, which causes an upstream reactance.

The response created by the capacitor depends on the frequency of the input signal. R2 drains the accumulated current from the capacitor when the entire circuit is turned off. It is capable of storing up to 400V, and resistor R1 limits this flow. The next step in the do-it-yourself LED lamp circuit is a bridge rectifier, which is designed to convert an AC signal to DC. Capacitor C2 serves to eliminate ripple in a rectified DC signal.

Resistor R3 serves as a current limiter for all LEDs. The circuit uses white LEDs that have a voltage drop of about 3.5V and draw 30mA of current. Since the LEDs are connected in series, the current consumption is very low. Therefore, this circuit becomes energy efficient and has a budget manufacturing option.

Recycled LED lamp

LED 220 V can be easily made from non-working lamps, the repair or restoration of which is impractical. A strip of five LEDs is driven using a transformer. In a 0.7 uF / 400V circuit, the polyester capacitor C1 reduces the mains voltage. R1 is a discharging resistor that absorbs the stored charge from C1 when the AC input is turned off.

Resistors R2 and R3 limit the current flow when the circuit is turned on. Diodes D1 - D4 form a bridge rectifier that rectifies the reduced AC voltage, while C2 acts as a filter capacitor. Finally, the zener diode D1 provides control of the LEDs.

The procedure for making a table lamp with your own hands:

LED for car

Using LED tape, you can easily make a beautiful home-made car exterior lighting. You need to use 4 LED strips of one meter each for a clear and bright glow. To ensure water tightness and strength, the joints are carefully treated with hot melt adhesive. Correct electrical connections are checked with a multimeter. The IGN relay is energized when the engine is running and turns off when the engine is turned off. To reduce the car voltage, which can reach 14.8 V, a diode is included in the circuit to ensure the durability of the LEDs.

DIY LED lamp for 220v

The cylindrical LED lamp provides a correct and even distribution of the generated illumination throughout 360 degrees, so that the entire room is evenly lit.

The lamp is equipped with an interactive function overvoltage protection that provides perfect protection of the device against all AC surges.

40 LEDs are combined into one long string of LEDs connected in series one after the other. For an input voltage of 220 V, you can connect about 90 LEDs in a row, for a voltage of 120 V - 45 LEDs.

The calculation is obtained by dividing the rectified voltage of 310 VDC (from 220 VAC) by the forward voltage of the LED. 310/3.3 = 93 units and for 120V inputs 150/3.3 = 45 units. If you reduce the number of LEDs below these numbers, there is a risk of overvoltage and failure of the assembled circuit.

How to make a light bulb with your own hands

The circuit consists of a high-voltage capacitor, a low-reactivity resistor to reduce current, two resistors, and a positive source capacitor to reduce input voltage and mains fluctuations. The surge correction is actually done by C2 installed after the bridge (between R2 and R3). All momentary voltage spikes are effectively absorbed by this capacitor, providing a clean and safe voltage for the built-in LEDs in the next stage of the circuit.

Parts list:

Homemade LEDs are protected, and their service life is increased by adding a zener diode along the power lines. The zener value shown is 310V/2W, and is suitable if the LED includes 93 to 96V LEDs. For other, fewer LED strings, the zener value must be reduced according to the overall LED string forward voltage calculation.

For example, if a 50 LED string is used and the LED has 3.3V, then we calculate 50×3.3 = 165V, so a 170V regulator will be enough to protect the LED.

Automatic LED Night Light Circuit

The circuit will automatically turn on the lamp at night and turn it off after a specified time using several transistors and a NE555 timer. The circuit is inexpensive and easy to install. LDR is used as a sensor here. During the daytime, the LDR resistance will be low, the voltage across it will drop, and transistor Q1 will be in wiring mode. When the light in the room drops, the resistance of the LDR increases, as does the voltage across it. Transistor Q1 turns off. The base of Q2 is connected to the emitter of Q1 and so Q2 is biased and in turn turns on IC1.

The NE555 automatically turns on when the power is turned on. Automatic start occurs with the help of capacitor C2. The output of IC1 remains high for the time determined by resistor R5 and capacitor C4. When IC1 outputs transistor Q3, it turns on, triggers T1, and the lamp lights up. The circuit includes a 9-volt battery to power the timer during power failures. Resistor R1, diode D1, capacitor C1 and Zener D3 form the power section of the circuit. R7 and R8 are current limiting resistors.

Do-it-yourself LED lighting scheme

Notes:

1. Preset R2 can be used to adjust the sensitivity of the circuit.
2. Preset R5 can be used to set the lamp on time.
3. With R5 @ 4.7M, the turn-on time will be about three hours.
4. The power L1 must not exceed 200W.
5. For BT136, it is recommended to use a heatsink.
6. IC1 must be mounted on a holder.

Measures to combat LED flicker

A do-it-yourself LED lamp from an energy-saving one has a huge advantage, but you need to work hard so that when working with homemade products, users are not bothered by excessive flickering of the LED:

To avoid the effect of LED flicker, you should always keep the above points in mind.

Because you need to correctly solve two problems at once:

1. Limit the forward current through the LED so it doesn't burn out.
2. Protect the LED from reverse current breakdown.

If you ignore any of these items, the LED will instantly be covered with a copper basin.

In the simplest case, you can limit the current through the LED with a resistor and / or a capacitor. And to prevent breakdown from reverse voltage, you can use a conventional diode or another LED.

Therefore, the simplest scheme for connecting an LED to 220V consists of only a few elements:

The protective diode can be almost anything, because. its reverse voltage will never exceed the forward voltage of the LED, and the current is limited by a resistor.

The resistance and power of the limiting (ballast) resistor depends on the operating current of the LED and is calculated according to Ohm's law:

R = (U in - U LED) / I

And the power dissipation of the resistor is calculated as follows:

P = (U in - U LED) 2 / R

where U in = 220 V,
U LED - direct (working) voltage of the LED. Usually it lies in the range of 1.5-3.5 V. For one or two LEDs, it can be neglected and, accordingly, the formula can be simplified to R \u003d U in / I,
I - LED current. For conventional indicator LEDs, the current will be 5-20 mA.

Ballast Resistor Calculation Example

Let's say we need to get the average current through the LED = 20mA, hence the resistor should be:

R \u003d 220V / 0.020A \u003d 11000 Ohm(we take two resistors: 10 + 1 kOhm)

P \u003d (220V) 2 / 11000 \u003d 4.4 W(we take with a margin: 5 W)

The required resistor value can be taken from the table below.

Table 1. Dependence of the LED current on the resistance of the ballast resistor.

Resistor resistance, kOhm	Amplitude value of the current through the LED, mA	Average LED current, mA	Average resistor current, mA	Resistor power, W
43	7.2	2.5	5	1.1
24	13	4.5	9	2
22	14	5	10	2.2
12	26	9	18	4
10	31	11	22	4.8
7.5	41	15	29	6.5
4.3	72	25	51	11.3
2.2	141	50	100	22

Other connection options

In the previous circuits, the protective diode was connected in anti-parallel, but it can also be placed like this:

This is the second circuit for switching on 220 volt LEDs without a driver. In this circuit, the current through the resistor will be 2 times less than in the first variant. And, therefore, 4 times less power will be allocated on it. This is a definite plus.

But there is also a minus: the full (amplitude) mains voltage is applied to the protective diode, so any diode will not work here. You will have to pick up something with a reverse voltage of 400 V and above. But these days, that's not a problem at all. Perfect, for example, is the ubiquitous 1000 volt diode - 1N4007 (KD258).

Despite the common misconception, during the negative half-cycles of the mains voltage, the LED will still be in a state of electrical breakdown. But due to the fact that the resistance of the reverse-biased p-n junction of the protective diode is very high, the breakdown current will not be enough to disable the LED.

Attention! All the simplest circuits for connecting 220 volt LEDs have a direct galvanic connection with the network, so touching ANY point in the circuit is EXTREMELY DANGEROUS!

To reduce the value of the touch current, you need to halve the resistor into two parts, so that it turns out as shown in the pictures:

Thanks to this solution, even by swapping the phase and zero, the current through a person to the "ground" (in case of an accidental touch) cannot exceed 220/12000 = 0.018A. And it's not so dangerous anymore.

What about pulsations?

In both circuits, the LED will only glow during the positive half-cycle of the mains voltage. That is, it will flicker at a frequency of 50 Hz or 50 times per second, and the ripple span will be 100% (10 ms on, 10 ms off, and so on). It will be visible to the eye.

In addition, when flashing LEDs illuminate any moving objects, such as fan blades, bicycle wheels, etc., a stroboscopic effect will inevitably occur. In some cases, this effect may be unacceptable or even dangerous. For example, when working at a machine tool, it may seem that the cutter is stationary, but in fact it rotates at breakneck speed and is just waiting for you to stick your fingers into it.

To make the ripple less noticeable, you can double the LED turn-on frequency using a full-wave rectifier (diode bridge):

Note that compared to circuit #2, with the same resistor value, we got twice the average current. And, accordingly, four times the power dissipation of the resistors.

At the same time, there are no special requirements for the diode bridge, the main thing is that the diodes of which it consists can withstand half the operating current of the LED. The reverse voltage on each of the diodes will be quite negligible.

Still, as an option, you can organize an anti-parallel connection of two LEDs. Then one of them will burn during the positive half-wave, and the second - during the negative.

The trick is that with this inclusion, the maximum reverse voltage on each of the LEDs will be equal to the forward voltage of the other LED (a few volts maximum), so each of the LEDs will be reliably protected from breakdown.

LEDs should be placed as close to each other as possible. Ideally, try to find a dual LED, where both crystals are placed in the same package and each has its own conclusions (although I have never seen such ones).

Generally speaking, for LEDs that perform an indicator function, the magnitude of the pulsations is not very important. For them, the most important thing is the most noticeable difference between the on and off states (on / off indication, playback / recording, charge / discharge, normal / accident, etc.)

But when creating fixtures, you should always try to minimize pulsations. And not so much because of the dangers of the stroboscopic effect, but because of their harmful effects on the body.

What ripples are considered acceptable?

It all depends on the frequency: the lower it is, the more noticeable the ripple. At frequencies above 300 Hz, the ripples become completely invisible and are not normalized at all, that is, even 100% are considered the norm.

Despite the fact that light pulsations at frequencies of 60-80 Hz and above are not visually perceived, however, they can cause increased eye fatigue, general fatigue, anxiety, decreased visual performance, and even headaches.

To prevent the above consequences, the international standard IEEE 1789-2015 recommends the maximum level of brightness ripple for a frequency of 100 Hz - 8% (guaranteed safe level - 3%). For a frequency of 50 Hz, these will be 1.25% and 0.5%, respectively. But this is for perfectionists.

In fact, in order for the brightness pulsations of the LED to stop at least somehow annoying, it is enough that they do not exceed 15-20%. This is exactly the level of flickering of medium-power incandescent lamps, and no one has ever complained about them. Yes, and our Russian SNiP 23-05-95 allows light flickering at 20% (and only for particularly painstaking and responsible work, the requirement is increased to 10%).

In accordance with GOST 33393-2015 "Buildings and structures. Methods for measuring the pulsation coefficient of illumination" to assess the magnitude of pulsations, a special indicator is introduced - the coefficient of pulsations (K p).

Coeff. ripple is generally calculated using a complex formula using an integral function, but for harmonic oscillations the formula is simplified to the following:

K p \u003d (E max - E min) / (E max + E min) ⋅ 100%,

where E max is the maximum illumination value (amplitude), and E min is the minimum.

We will use this formula to calculate the capacitance of a smoothing capacitor.

You can very accurately determine the pulsations of any light source using a solar panel and an oscilloscope:

How to reduce pulsations?

Let's see how to turn on the LED in a 220 volt network to reduce ripple. To do this, the easiest way is to solder a storage (smoothing) capacitor in parallel with the LED:

Due to the non-linear resistance of LEDs, calculating the capacitance of this capacitor is a rather non-trivial task.

However, this task can be simplified by making a few assumptions. First, imagine the LED as an equivalent fixed resistor:

And secondly, to pretend that the brightness of the LED (and, consequently, the illumination) has a linear dependence on the current.

Calculation of the capacitance of the smoothing capacitor

Let's say we want to get the coefficient. ripple 2.5% at a current through the LED 20 mA. And let us have an LED at our disposal, on which 2 V drops at a current of 20 mA. The network frequency, as usual, is 50 Hz.

Since we decided that the brightness depends linearly on the current through the LED, and we presented the LED itself as a simple resistor, we can safely replace the illumination in the formula for calculating the ripple coefficient by the voltage on the capacitor:

K p \u003d (U max - U min) / (U max + U min) ⋅ 100%

We substitute the initial data and calculate U min:

2.5% = (2V - Umin) / (2V + Umin) ⋅ 100% => Umin = 1.9V

The period of voltage fluctuations in the network is 0.02 s (1/50).

Thus, the voltage waveform on the capacitor (and therefore on our simplified LED) will look something like this:

We recall trigonometry and calculate the charge time of the capacitor (for simplicity, we will not take into account the resistance of the ballast resistor):

t charge = arccos(U min /U max) / 2πf = arccos(1.9/2) / (2 ⋅ 3.1415⋅ 50) = 0.0010108 s

The rest of the period of the conder will be discharged. Moreover, the period in this case must be halved, because. we use a full-wave rectifier:

t razr \u003d T - t charge \u003d 0.02 / 2 - 0.0010108 \u003d 0.008989 s

It remains to calculate the capacity:

C=I LED ⋅ dt/dU = 0.02 ⋅ 0.008989/(2-1.9) = 0.0018 F (or 1800 uF)

In practice, it is unlikely that anyone will install such a large conder for the sake of one small LED. Although, if the task is to get a ripple of 10%, then only 440 microfarads are needed.

We increase efficiency

Have you noticed how much power is dissipated in the quenching resistor? Wasted power. Is there any way to reduce it?

It turns out that it is still possible! It is enough to take a reactive resistance (capacitor or inductor) instead of active resistance (resistor).

We, perhaps, will immediately discard the inductor because of its bulkiness and possible problems with the self-induction EMF. And what about capacitors, you can think.

As you know, a capacitor of any capacitance has an infinite resistance for direct current. But the resistance to alternating current is calculated by this formula:

Rc = 1 / 2πfC

that is, the larger the capacitance C and the higher the frequency f- the lower the resistance.

The beauty is that on the reactance and the power is also reactive, that is, not real. It's like it's there, but it's like it's not there. In fact, this power does not do any work, but simply returns back to the power source (to the outlet). Household meters do not take it into account, so you do not have to pay for it. Yes, it creates an additional load on the network, but you, as the end user, are unlikely to be very worried =)

Thus, our do-it-yourself LED power supply circuit from 220V takes the following form:

But! It is in this form that it is better not to use it, since in this circuit the LED is vulnerable to impulse noise.

Turning on or off a powerful inductive load located on the same line as you (air conditioner motor, refrigerator compressor, welding machine, etc.) leads to very short voltage surges in the network. Capacitor C1 represents almost zero resistance for them, therefore a powerful impulse will go straight to C2 and VD5.

Another dangerous moment occurs if the circuit is turned on at the moment of the antinode of the voltage in the network (that is, at the very moment when the voltage in the outlet is at its peak value). Because C1 is completely discharged at this point, then there is too much current inrush through the LED.

All this over time leads to progressive degradation of the crystal and a decrease in the brightness of the glow.

In order to avoid such unfortunate consequences, the circuit must be supplemented with a small quenching resistor of 47-100 ohms and a power of 1 watt. In addition, the resistor R1 will act as a fuse in case of breakdown of the capacitor C1.

It turns out that the scheme for connecting the LED to the 220 volt network should be like this:

And there remains one more small nuance: if you pull this circuit out of the socket, then some charge will remain on the capacitor C1. The residual voltage will depend on the moment at which the power circuit was broken and in some cases may exceed 300 volts.

And since the capacitor has nowhere to discharge, except through its internal resistance, the charge can be stored for a very long time (a day or more). And all this time, the conder will be waiting for you or your child, through which it will be possible to discharge properly. Moreover, in order to get an electric shock, you do not need to climb into the bowels of the circuit, just touch both pins of the plug.

To help the conder get rid of unnecessary charge, we will connect any high-resistance resistor (for example, 1 MΩ) in parallel with it. This resistor will have no effect on the design mode of the circuit. It won't even warm up.

Thus, the finished scheme for connecting an LED to a 220V network (taking into account all the nuances and improvements) will look like this:

The value of the capacitance of the capacitor C1 to obtain the desired current through the LED can be immediately taken from, or you can calculate it yourself.

Calculation of the quenching capacitor for the LED

I will not give tedious mathematical calculations, I will immediately give a ready-made capacitance formula (in Farads):

C \u003d I / (2πf√ (U 2 in - U 2 LED))[F],

where I is the current through the LED, f is the frequency of the current (50 Hz), U in is the effective value of the mains voltage (220V), U LED is the voltage on the LED.

If the calculation is carried out for a small number of series-connected LEDs, then the expression √ (U 2 in - U 2 LED) is approximately equal to U in, therefore the formula can be simplified:

C ≈ 3183 ⋅ I LED / U in[µF]

and, since we are doing calculations under U in = 220 volts, then:

C≈ 15⋅I LED[µF]

Thus, when the LED is turned on at 220 V, for every 100 mA of current, approximately 1.5 μF (1500 nF) of capacitance will be required.

Who is at odds with mathematics, pre-calculated values ​​can be taken from the table below.

Table 2. Dependence of the current through the LEDs on the capacitance of the ballast capacitor.

C1	15nF	68nF	100nF	150nF	330nF	680nF	1000nF
I LED	1mA	4.5mA	6.7mA	10mA	22mA	45mA	67mA

A little about the capacitors themselves

It is recommended to use noise-suppressing capacitors of class Y1, Y2, X1 or X2 for a voltage of at least 250 V as quenching capacitors. They have a rectangular case with numerous certificate designations on it. They look like this:

In short, then:

• X1- used in industrial devices connected to a three-phase network. These capacitors are guaranteed to withstand a 4 kV surge;
• X2- the most common. They are used in household appliances with a rated mains voltage of up to 250 V, withstand surges up to 2.5 kV;
• Y1- operate at rated mains voltage up to 250 V and withstand impulse voltage up to 8 kV;
• Y2- a fairly common type, can be used with a mains voltage of up to 250 V and can withstand impulses of 5 kV.

It is permissible to use domestic film capacitors K73-17 for 400 V (or better - for 630 V).

Today, Chinese "chocolates" (CL21) are widely used, but in view of their extremely low reliability, I highly recommend resisting the temptation to use them in your schemes. Especially as ballast capacitors.

Attention! Polar capacitors should never be used as ballast capacitors!

So, we looked at how to connect an LED to 220V (schemes and their calculation). All the examples given in this article are well suited for one or more low-power LEDs, but are completely impractical for powerful fixtures, such as lamps or spotlights - it is better to use for them, which are called drivers.