LED lamp circuit based on one LED. What determines the lifespan of an LED? Online calculators for determining resistor values ​​by color coding

Despite the diversity on the country's shelves, they remain unrivaled due to their cost-effectiveness and durability. However, a quality product is not always purchased, because in a store you cannot take the product apart for inspection. And even in this case, it is not a fact that everyone will determine from what parts it is assembled. burn out, and buying new ones becomes expensive. The solution is to repair LED lamps yourself. Even a novice home craftsman can do this work, and the parts are inexpensive. Today we will figure out how to check in what cases the product is repaired and how to do it.

It is known that LEDs cannot operate directly from a 220 V network. To do this, they need additional equipment, which most often fails. We'll talk about it today. Let's consider the circuit, without which the operation of the lighting device is impossible. At the same time, we will conduct an educational program for those who do not understand anything about radio electronics.

The 220 V LED lamp driver circuit consists of:

• diode bridge;
• resistance;
• resistors.

The diode bridge serves to rectify the current (converts it from alternating to direct). On the graph it looks like cutting off a half-wave of a sine wave. Resistors limit the current, and capacitors store energy, increasing the frequency. Let's look at the operating principle of a 220 V LED lamp.

The principle of operation of the driver in an LED lamp

View on the diagram	Operating procedure
	A voltage of 220 V is supplied to the driver and passes through a smoothing capacitor and a current-limiting resistor. This is necessary in order to protect the diode bridge.
	Voltage is supplied to a diode bridge, consisting of four differently directed diodes, which cut off the half-wave of the sine wave. The output current is constant.
	Now, by means of a resistance and a capacitor, the current is again limited and the desired frequency is set.
	Voltage with the necessary parameters is supplied to unidirectional light diodes, which also serve as a current limiter. Those. when one of them burns out, the voltage increases, which leads to failure of the capacitor if it is not powerful enough. This happens in Chinese products. High-quality devices are protected from this.

Having understood the principle of operation and the driver circuit, the decision on how to repair a 220V LED lamp will no longer seem difficult. If we talk about quality products, then you shouldn’t expect any troubles from them. They work for the entire prescribed period and do not fade, although there are “diseases” to which they are also susceptible. Let's talk about how to deal with them now.

Reasons for failure of LED lighting devices

To make it easier to understand the reasons, let’s summarize all the data in one common table.

Good to know! Repair of LED lamps cannot be carried out indefinitely. It is much easier to eliminate negative factors that affect durability and not purchase cheap products. Savings today will result in costs tomorrow. As economist Adam Smith said, “I am not rich enough to buy cheap things.”

Repairing a 220 V LED lamp with your own hands: nuances of the work

Before you repair an LED lamp with your own hands, pay attention to some details that require less labor. Checking the cartridge and the voltage in it is the first thing to do.

Important! Repairing LED lamps requires a multimeter - without it you won’t be able to ring the driver elements. You will also need a soldering station.

A soldering station is necessary for repairing LED chandeliers and lamps. After all, overheating of their elements leads to failure. The heating temperature when soldering should not be higher than 2600, while the soldering iron heats up more. But there is a way out. We use a piece of copper wire with a cross-section of 4 mm, which is wound onto the soldering iron tip in a tight spiral. The more you lengthen the tip, the lower its temperature. It is convenient if the multimeter has a thermometer function. In this case, it can be adjusted more accurately.

But before you make any repairs LED spotlights, chandeliers or lamps, you need to determine the cause of failure.

How to disassemble an LED light bulb

One of the problems that a novice home DIYer faces is how to disassemble an LED light bulb. To do this you will need an awl, solvent and a syringe with a needle. The LED lamp diffuser is glued to the body with sealant, which needs to be removed. Carefully running an awl along the edge of the diffuser, inject the solvent with a syringe. After 2-3 minutes, easily twisting, the diffuser is removed.

Some lighting fixtures are made without sealant. In this case, it is enough to rotate the diffuser and remove it from the body.

Determining the cause of failure of an LED light bulb

After disassembling the lighting fixture, pay attention to the LED elements. Burnt is often identified visually: it has scorch marks or black dots. Then we replace the faulty part and check its functionality. We will tell you in detail about the replacement in step-by-step instructions.

If the LED elements are in order, move on to the driver. To check the functionality of its parts, you need to remove them from the printed circuit board. The value of resistors (resistance) is indicated on the board, and the parameters of the capacitor are indicated on the case. When testing with a multimeter in the appropriate modes, there should be no deviations. However, often failed capacitors are identified visually - they swell or burst. Solution - replacement with suitable technical parameters.

Replacing capacitors and resistances, unlike LEDs, is often done with a regular soldering iron. In this case, care should be taken not to overheat nearby contacts and elements.

Replacing light bulb LEDs: how difficult is it?

Subject to availability soldering station or a hairdryer, this job is simple. It is more difficult to work with a soldering iron, but it is also possible.

Good to know! If you don’t have working LED elements at hand, you can install a jumper instead of the burnt one. Such a lamp will not work for a long time, but it will be possible to gain some time. However, such repairs are carried out only if the number of elements is more than six. Otherwise, a day is the maximum work of the repair product.

Modern lamps operate on SMD LED elements that can be desoldered from LED strip. But it is worth choosing the ones that are suitable according to technical characteristics. If there are none, it is better to change everything.

Related article:

For the right choice You need to know not only general things about LED devices. Information about modern models, electrical diagrams of working devices. In this article you will find answers to these and other practical questions.

Repairing an LED lamp driver if you have an electrical diagram of the device

If the driver consists of SMD components that are smaller in size, we will use a soldering iron with copper wire on the sting. At visual inspection A burnt element has been identified - unsolder it and select the appropriate one according to the markings. There are no visible damages - this is more difficult. You will have to solder all the parts and ring them separately. Having found a burnt one, we replace it with a functional one. It is convenient to use tweezers for this.

Useful advice! You should not remove all elements from the printed circuit board at the same time. They are similar in appearance, you can later confuse the location. It is better to unsolder the elements one by one and, after checking, mount them in place.

How to check and replace the power supply of LED lamps

When installing lighting in rooms with high humidity (or), stabilizing ones are used, which reduce the voltage to a safe one (12 or 24 volts). The stabilizer can fail for several reasons. The main ones are excessive load (power consumption of luminaires) or incorrect selection of the unit’s degree of protection. Such devices are repaired in specialized services. At home, this is unrealistic without equipment and knowledge in the field of radio electronics. In this case, the power supply will have to be replaced.

Very important! All work to replace the stabilizing LED power supply is carried out with the voltage removed. Don't rely on the switch - it may not be connected correctly. The voltage is turned off in the apartment's distribution panel. Remember that touching live parts with your hand is dangerous.

You need to pay attention to the technical characteristics of the device - the power must exceed the parameters of the lamps that are powered from it. Having disconnected the failed unit, we connect a new one according to the diagram. She is in technical documentation device. This does not present any difficulties - all wires are color-coded, and the contacts are labeled with letters.

The degree of protection of the device (IP) also plays a role. For a bathroom, the device must be marked at least IP45.

Article

The article describes the design of LED lamps. Several circuits of different complexity are considered and recommendations are given for the independent production of LED light sources connected to a 220 V network.

Advantages of energy saving lamps

The benefits of energy-saving lamps are widely known. First of all, this is actually low energy consumption, and in addition, high reliability. Currently, fluorescent lamps are the most widely used. Such a lamp gives the same illumination as a hundred-watt incandescent lamp. It is easy to calculate that energy savings are five times.

IN lately LED lamps are being introduced into production. Their efficiency and durability indicators are much higher than those of fluorescent lamps. In this case, electricity is consumed ten times less than incandescent lamps. The durability of LED lamps can reach 50 or more thousand hours.

New generation light sources, of course, are more expensive than simple incandescent lamps, but they consume significantly less power and have increased durability. The last two indicators are designed to compensate for the high cost of new types of lamps.

Practical LED lamp circuits

As a first example, we can consider the design of an LED lamp developed by SEA Electronics using specialized chips. The electrical circuit of such a lamp is shown in Figure 1.

Figure 1. Diagram of an LED lamp from SEA Electronics

Ten years ago, LEDs could only be used as indicators: the luminous intensity was no more than 1.5...2 microcandelas. Nowadays, ultra-bright LEDs have appeared, whose radiation intensity reaches several tens of candelas.

When using powerful LEDs Together with semiconductor converters, it became possible to create light sources that can withstand competition with incandescent lamps. A similar converter is shown in Figure 1. The circuit is quite simple and contains a small number of parts. This is achieved through the use of specialized microcircuits.

The first microcircuit IC1 BP5041 is an AC/DC converter. Its block diagram is presented in Figure 2.

Figure 2. Block diagram BP5041.

The microcircuit is made in a SIP type housing shown in Figure 3.

Figure 3.

The entire device is protected by fuse F1, the rating of which should not exceed that indicated in the diagram. Capacitor C3 is designed to smooth out ripples in the output voltage of the converter. It should be noted that the output voltage does not have galvanic isolation from the network, which is not at all necessary in this circuit, but requires special care and compliance with safety rules during manufacturing and commissioning.

Capacitors C3 and C2 must have an operating voltage of at least 450 V. Capacitor C2 must be film or ceramic. Resistor R1 can have a resistance in the range of 10...20 Ohms, which is enough for normal operation converter

The use of this converter eliminates the need for a step-down transformer, which significantly reduces the dimensions of the entire device.

A distinctive feature of the BP5041 microcircuit is the presence of a built-in inductor as shown in Figure 2, which allows you to reduce the number of attachments and the overall size of the circuit board.

Any diode with reverse voltage not less than 800 V and rectified current not less than 500 mA. The widely used imported diode 1N4007 fully satisfies these conditions. A varistor VAR1 type FNR-10K391 is installed at the rectifier input. Its purpose is to protect the entire device from impulse noise and static electricity.

The second IC2, type HV9910, is a PWM current stabilizer for super-bright LEDs. Using an external MOSFET transistor, the current can be set in the range from a few milliamps to 1A. This current is set by resistor R3 in the circuit feedback. The microcircuit is available in SO-8 (LG) and SO-16 (NG) packages. Her appearance is shown in Figure 4, and in Figure 5 is a block diagram.

Figure 4. HV9910 chip.

Figure 5. Block diagram of the HV9910 chip.

Using resistor R2, the frequency of the internal oscillator can be changed in the range of 20…120 KHz. With the resistance of resistor R2 indicated on the diagram, it will be about 50 KHz.

Choke L1 is designed to store energy while transistor VT1 is open. When the transistor closes, the energy accumulated in the inductor is given to the LEDs D3...D6 through a high-speed Schottky diode D2.

Here is the time to remember self-induction and Lenz’s rule. According to this rule, the induced current always has such a direction that its magnetic flux compensates for the change in the external magnetic flux that caused this current. Therefore, the direction of the self-induction emf has the opposite direction to the direction EMF source nutrition. This is why LEDs are included in reverse side in relation to the supply voltage (pin 1 of IC2, indicated in the diagram as VIN). Thus, the LEDs emit light due to the self-induction emf of coil L1.

This design uses 4 ultra-bright LEDs of the TWW9600 type, although it is quite possible to use other types of LEDs produced by other companies.

To control the brightness of the LEDs, the chip has a PWM_D input, PWM - modulation from an external generator. This circuit does not use such a function.

When making such an LED lamp yourself, you should use a housing with a screw base of size E27 from unusable energy saving lamp, with a power of at least 20 W. The appearance of the structure is shown in Figure 6.

Figure 6. Homemade led lamp.

Although the described scheme is quite simple, it is recommended for self-made It is not always possible: either it will not be possible to buy the parts indicated in the diagram, or the assembler is insufficiently qualified. Some may simply be afraid: “What if I don’t succeed?” For such situations, we can offer several more options that are simpler both in terms of circuit design and in terms of purchasing parts.

More simple circuit LED lamp is shown in Figure 7.

Figure 7.

This diagram shows that a bridge rectifier with a capacitive ballast is used to power the LEDs, which limits the output current. Such power supplies are economical and simple, they are not afraid short circuits, their output current is limited capacitance capacitor. Such rectifiers are often called current stabilizers.

The role of capacitive ballast in the circuit is performed by capacitor C1. With a capacitance of 0.47 µF, the operating voltage of the capacitor must be at least 630V. Its capacity is designed so that the current through the LEDs is about 20 mA, which is the optimal value for LEDs.

The ripples of the bridge-rectified voltage are smoothed out by the electrolytic capacitor C2. To limit the charging current at the moment of switching on, resistor R1 is used, which also serves as a fuse in emergency situations. Resistors R2 and R3 are designed to discharge capacitors C1 and C2 after disconnecting the device from the network.

To reduce the size, the operating voltage of capacitor C2 was chosen to be only 100 V. In the event of a break (burnout) of at least one of the LEDs, capacitor C2 will be charged to a voltage of 310 V, which will inevitably lead to its explosion. To protect against such a situation, this capacitor is shunted by zener diodes VD2, VD3. Their stabilization voltage can be determined as follows.

With a rated current through the LED of 20 mA, a voltage drop is created across it, depending on the type, in the range of 3.2...3.8 V. (This property in some cases allows the use of LEDs as zener diodes). Therefore, it is easy to calculate that if 20 LEDs are used in the circuit, then the voltage drop across them will be 65...75 V. It is at this level that the voltage on capacitor C2 will be limited.

Zener diodes should be selected so that the total stabilization voltage is slightly higher than the voltage drop across the LEDs. In this case, during normal operation, the zener diodes will be closed and will not affect the operation of the circuit. The 1N4754A zener diodes indicated in the diagram have a stabilization voltage of 39 V, and those connected in series have 78 V.

If at least one of the LEDs breaks, the zener diodes will open and the voltage on capacitor C2 will be stabilized at 78 V, which is clearly lower than the operating voltage of capacitor C2, so an explosion will not occur.

The design of a homemade LED lamp is shown in Figure 8. As can be seen from the figure, it is assembled in a housing from an unusable energy-saving lamp with an E-27 base.

Figure 8.

The printed circuit board on which all the parts are placed is made of foil fiberglass by any of the methods available at home. To install LEDs on the board, holes with a diameter of 0.8 mm are drilled, and for other parts - 1.0 mm. The PCB drawing is shown in Figure 9.

Figure 9. Printed circuit board and the location of parts on it.

The location of the parts on the board is shown in Figure 9c. All parts except LEDs are installed on the side of the board, where there are no printed tracks. A jumper is installed on the same side, also shown in the figure.

After installing all the parts, LEDs are installed on the foil side. Installation of LEDs should begin from the middle of the board, gradually moving to the periphery. The LEDs must be soldered in series, that is, the positive terminal of one LED is connected to the negative terminal of the other.

The diameter of the LED can be anything within 3…10 mm. In this case, the LED leads should be left at least 5 mm long from the board. Otherwise, the LEDs can simply overheat when soldering. The duration of soldering, as recommended in all manuals, should not exceed 3 seconds.

After the board has been assembled and adjusted, its leads must be soldered to the base, and the board itself must be inserted into the case. In addition to the specified housing, it is possible to use a more miniature housing, but in this case it will be necessary to reduce the size of the printed circuit board, not forgetting, however, the dimensions of capacitors C1 and C2.

The advent of LED or LED lamps contributed to the beginning of a new stage in the lighting industry. More recently, such lighting fixtures were extremely rare, but now a huge assortment of different LED lamps is displayed by everyone. large stores. The LED, unlike a conventional incandescent lamp, has its own startup circuit.

It is installed in the light bulb itself, between the imitation bulb and the socket. Therefore, this place is made opaque. Getting to the board with diodes is not that difficult, but some effort will be required for disassembly. Although experience shows that most manufacturers use similar models of starting devices for this, small differences still remain.

Friends, I welcome everyone to the “Electrician in the House” website. Today I want to give you an overview of the insides of the LED lamps that I ordered from Aliexpress. The lamp consists of 72 diodes. It uses SMD LEDs, also known as Surface Mounting Device. Let's start disassembling, I think you will also be very interested.

Operating principle of LED lamp

Produced led light bulbs for 220V they may differ in external design, but the principle of the internal structure remains the same for all models. Light emission in lamps is carried out by LEDs, the number and size of crystals of which can vary depending on the power and cooling capabilities. Their color spectrum is determined by the substance included in the structure of each crystal.

To get to the starting driver, you need to carefully remove the protective “skirt” of the lamp. A printed circuit board or assembly of interconnected radio elements will open under it. At the driver input there is a diode bridge connected to the electric base of the lamp in contact with the socket. Thanks to it, the alternating supply voltage is rectified into constant voltage, supplied to the board and through it supplied to the LEDs.

To better dissipate the emitted flux and protect the crystals from touching, as well as to avoid their contact with foreign objects, a diffuser is installed outside safety glass(transparent plastic flask). Therefore, in their appearance they are very reminiscent of traditional light sources.

To screw the light bulb into the socket, their bases are made standard sizes E14, E27, E40, etc. This allows you to use LED lamps in home network without resorting to any changes in the electrical wiring.

Design and purpose of lamp parts

Each LED lamp consists of the following parts:

#1 . Diffuser - a special hemisphere that increases the angle and evenly scatters the directed beam of LED radiation. In most cases, the element is made from transparent and translucent plastics or frosted polycarbonate. Due to this, the products do not break when dropped. The element is absent only in analogues of fluorescent lamps; there it is replaced by a special reflector. In devices with LEDs, the heating of the hemisphere is insignificant and several times less than in conventional filamentous electric lamps.

#2 . LED chips– the main components of new generation lamps. They are installed either one at a time or in dozens. Their number depends on the design features of the product, its size, power and the presence of devices for heat removal. U good producers It is not practiced to skimp on quality LED matrices, since they determine all the operating parameters of the emitter and the duration of its operation. However, in the world such companies can be counted on one hand. The diodes in the matrices are interconnected, and if one fails, the entire lamp fails.

#3 . Printed circuit board. In their manufacture, anodized aluminum alloys are used, which can effectively remove heat to the radiator, which will create optimal temperature for uninterrupted operation of the chips.

#4 . Radiator, which removes heat from a printed circuit board with LEDs recessed in it. For casting radiators, aluminum and its alloys are also chosen, as well as special forms With a large number separate plates that help increase the heat dissipation area.

#5 . Capacitor, cleaning voltage ripple, supplied to the LED crystals from the driver board.

#6 . Driver that smoothes, reduces and stabilizes the input voltage electrical network. No one can do without this miniature printed circuit board. LED matrix. There are external and built-in drivers. Majority modern lamps equipped with built-in devices that are mounted directly in their housing.

#7 . Polymer base, resting closely against the base part, protecting the housing from electrical breakdowns, and those changing light bulbs from accidental electric shock.

#8 . Base providing connection to the cartridges. Typically, nickel-plated brass is used in its manufacture. This guarantees good contact and long-term corrosion protection.

Also, a significant difference between LED devices and their conventional prototypes was the location of the maximum heating zone. For other types of emitters, heat spreads from the outside of the surface. LED crystals heat up their printed circuit board from the inside. Therefore, they require timely removal of heat from inside the lamp, and this is structurally solved by installing cooling radiators.

Design of a corn lamp

For some reason, everyone calls the lamp that we are going to disassemble today “corn”. Although looking at the appearance there really is a resemblance. I ordered a whole set of these lighting lamps for a soft box. For those who haven't seen it yet, there is a video on the YouTube channel.

External provides open access to the diodes and in case of failure, you can easily test them with a multimeter and determine the faulty diode.

The lamp consists of ten side plates with six LEDs on each plate. Plus, 12 more diodes are soldered on the top cover. A total of 72 diodes are obtained.

Let's start disassembling this miracle to quickly see the insides. Before that, you need to carefully examine the body and understand which parts are connected to each other.

On the top cover you can see parts that fit together; the cover has grooves. That's what we'll be filming. To do this, take a thin screwdriver or knife and carefully pry the lid evenly around the entire perimeter.

As you can see in the photo there is practically nothing inside. The driver is attached to the wall with double-sided tape. The side plates can be easily pulled out of the grooves. There are a lot of connecting wires around.

In the depths you can see the wires through which the power supply voltage 220 Volt from the base to the driver input. There are two wires coming out of the driver (red and white). LEDs are connected to them.

I decided to measure the voltage at the driver output. Multimeter shows voltage 77 volts (DC). Connection diagram for all diodes performed parallel-serial. A group of three diodes connected in parallel is connected in series with another group, and so on. In total there are 24 “links” of “three diodes”.

Here is a simple device for a 220 Volt LED lamp of the “corn” type.

I didn't like the fact that this lamp does not have a radiator. And as you know, friends, the main problem with LEDs is heating and heat dissipation. There are no metal objects in it at all, with the exception of the circuit boards on which the diodes themselves are soldered; they are made of aluminum. The case is made of ceramic, there are four ventilation holes near the base.

I don't know if this is good or bad. Maybe you can tell me, friends, write in the comments.

We disassemble the LED lamp “Housekeeper”

The next LED lamp that I want to disassemble and show you its structure is the “Housekeeper”, with a power of 7 W. She has been serving me faithfully for two years now. Specifications are shown in the photo.

Like the previous lamp, the base size is E27. The base itself is attached to the body with special in-depth grooves. It is impossible to remove it without drilling or other damage.

The lamp body is made of aluminum and has a basket-like shape. There are ribs on the sides for air circulation and additional heat removal.

This lamp has a hemispherical diffuser made of matte plastic. Unlike the previous version, where everything is cowardly and held together, here everything is assembled very well, in fact - one monolithic structure.

How to disassemble an LED lamp of this type? Here the insides are hidden behind the diffuser. We take a screwdriver with a thin tip and pry off the flask.

An aluminum plate with SMD 5730 diodes is fixed in the center on three bolts. There are 14 diodes. In my opinion, all the LEDs are connected in series. I can’t say for sure, since the connecting tracks on the board are invisible. If one of them fails, the lamp will stop working.

Thermal paste (white, similar in structure to regular silicone sealant) is applied at the point where the board comes into contact with the metal case.

By unscrewing three screws and lifting the board, you can see the main thing - the driver.

The driver is compactly located in the central tube.

Let's measure what voltage the driver produces. The multimeter shows voltage within 44 Volts.

Design and principle of operation of LED lamps. Main parts of the lighting device:

LEDs;
- driver;
- base;
- frame.

The principle of its operation completely repeats the processes occurring in an ordinary semiconductor diode With p-n junction om from silicon or germanium: when a positive potential is applied to the anode, and a negative potential to the cathode, the materials begin to move negatively charged electrons to the anode, and holes to the cathode. As a result, the diode passes electric current in only one forward direction.

However, the LED is made of other semiconductor materials, which, when bombarded in the forward direction by charge carriers (electrons and holes), carry out their recombination and transfer to another energy level. As a result, photons are released - elementary particles electromagnetic radiation light range.

Even in electrical circuits, the designations of ordinary diodes are used as their designations, only with the addition of two arrows indicating the emission of light.

Semiconductor materials have different photon emission properties. Substances such as gallium arsenide (GaAs) and gallium nitride (GaN), being direct-gap semiconductors, are simultaneously transparent to the visible spectrum of light waves. When replacing them p-n layers transition, light is released.

The arrangement of layers used in an LED is shown in the figure below. Their small thickness of the order of 10÷15 nm (nanomicrons) is created by special methods of chemical vapor deposition. The layers contain contact pads for the anode and cathode.

As with any physical process, during the conversion of electrons into photons there are energy losses due to the following reasons:

Some light particles are simply lost inside even such a thin layer;
- when leaving the semiconductor, optical refraction of light waves occurs at the crystal/air boundaries, distorting the wavelength.

The use of special measures, for example the use of a sapphire substrate, allows you to create a greater luminous flux. Such designs are used for installation in lighting lamps, but not for conventional LEDs used as indicators, shown in the figure below.

They have a lens made of epoxy resin and a reflector to direct the light. Depending on the purpose, the light can spread over a wide angle range of 5-160°.

Expensive LEDs produced for lighting lamps are manufactured by manufacturers with a Lambertian diagram. This means that their brightness is constant in space and does not depend on the direction of radiation and the viewing angle.

The dimensions of the crystal are very small and a small flux of light can be obtained from one source. Therefore, for lighting lamps, such LEDs combine quite in large groups. At the same time, creating uniform illumination from them in all directions is very problematic: each LED is a point source.

The frequency spectrum of light waves from semiconductor materials is much narrower than from conventional incandescent lamps or the sun, which tires human eyes and creates a certain discomfort. In order to correct this drawback, a phosphor layer is introduced into individual LED designs for lighting.

The amount of emitted luminous flux semiconductor materials depends on the current passing through the pn junction. The higher the current, the higher the radiation, but up to a certain value.

Small dimensions, as a rule, do not allow the use of currents exceeding 20 milliamps for indicator structures. The powerful lighting lamps heat dissipation and additional protection measures are used, the use of which, however, is strictly limited.

At startup, the luminous flux of the lamp increases proportionally with increasing current, but then begins to decrease due to the formation of thermal losses. It should be understood that the process of releasing photons from a conductor is not associated with thermal energy; LEDs are cold light sources.

However, the current passing through the LED at the contact points of various layers and electrodes overcomes the transition resistance of these areas, causing heating of the materials. The generated heat initially only creates energy loss, but as the current increases, it can damage the structure.

The number of LED crystals installed in one lamp can exceed a hundred working elements. Each of them must be supplied with the optimal current. For this purpose, fiberglass boards with conductive tracks are created. They can have very different designs.

Soldered to the contact pads of the boards led crystals. Most often, they are formed into certain groups and powered sequentially with each other. The same current is passed through each created chain.

Such a scheme is easier to implement technically, but it has one main drawback - if any one contact is broken, the entire group stops shining, which is the main reason for lamp failure.

Drivers. Supply DC voltage Each group of LEDs is connected to a special device, which was previously called a power supply, but is now called a “driver”.

This device has the function of converting the input network voltage, for example, ~220 Volt residential or 12 Volt automobile network into the optimal power supply for each serial group.

Supplying one stabilized current to each crystal according to parallel circuit technically complex and used in rare cases. The driver can operate on the basis of a transformer or other circuit. The following options are common among them. Depending on the configuration and number of elements used, they can be different:

The simplest and cheapest drivers are powered from a stabilized voltage, the network of which is protected from surges and surges. They may even lack a current-limiting resistor in the output power circuit, which is typical for rechargeable flashlights, the LEDs of which are often connected directly to the battery output.

As a result, it turns out that they are powered by an excessive current and, although they shine quite brightly, they very often burn out. When using cheap lamps with drivers without overvoltage protection for the lighting network, LEDs also often burn out without reaching the stated resource.

Well-designed power supplies produce virtually no heat during operation, while cheap or overloaded drivers waste some of their electricity on heating. Moreover, such useless losses electrical power can be comparable, and in some cases exceed the energy spent on the release of photons.

The task of reducing the amount of energy consumed is no longer just technical problem and moved into the area of ​​strategic direction of state policy. For the average consumer, this titanic struggle results in the fact that he is simply forcibly forced to switch from the familiar and simple-as-an-egg incandescent lamp to other light sources. For example, to LED lamps. For most people, the question of how an LED lamp works comes down only to the possibility of it practical application– is it possible to screw it into a standard socket and connect it to a 220 volt household network. A short excursion into the principles of its operation and structure will help you make an informed choice.

The operating principle of an LED lamp is based on much more complex physical processes than one that emits light through a red-hot metal thread. He is so interesting that it makes sense to get to know him better. It is based on the phenomenon of light emission that occurs at the point of contact of two dissimilar substances when passing through them electric current.

The most paradoxical thing about this is that the materials used to provoke the effect of light emission do not conduct electric current at all. One of them, for example, silicon is a ubiquitous substance and is constantly trampled underfoot. These materials will pass current, and only in one direction (that’s why they are called semiconductors), only if they are connected together. To do this, positively charged ions (holes) must predominate in one of them, and negative ones (electrons) in the other. Their presence or absence depends on the internal (atomic) structure of the substance and a non-specialist should not bother with the question of unraveling their nature.
The emergence of an electric current in a connection of substances with a predominance of holes or electrons is only half the battle. The process of transition from one to another is accompanied by the release of energy in the form of heat. But in the middle of the last century, mechanical compounds of substances were found in which the release of energy was also accompanied by a glow. In electronics, a device that allows current to pass in one direction is called a diode. Semiconductor devices made from materials that can emit light are called LEDs.

Initially, the effect of emitting photons from a semiconductor compound was possible only in a narrow part of the spectrum. They glowed red, green or yellow. The strength of this glow was extremely small. The LED was used only as an indicator lamp for a very long time. But now materials have been found whose combination emits light of much greater intensity and in a wide range, almost the entire visible spectrum. Almost, because a certain wavelength predominates in their glow. Therefore, there are lamps with a predominance of blue (cold) and yellow or red (warm) light.

Now that you understand in general terms the principle of operation of an LED lamp, you can move on to answering the question about the design of 220 V LED lamps.

Design of LED lamps

Externally, light sources that use the effect of photon emission when electric current passes through a semiconductor are almost no different from incandescent lamps. The main thing is that they have the usual metal base with a thread, which exactly replicates all standard sizes of incandescent lamps. This allows you to not change anything in the electrical equipment of the room to connect them.
However internal structure LED lamp 220 volts is very difficult. It consists of the following elements:

1) contact base;

2) a housing that simultaneously plays the role of a radiator;

3) power and control boards;

4) boards with LEDs;

5) transparent cap.

Power and control board

Understanding how 220 volt LED lamps work, first of all it is worth understanding that semiconductor elements cannot be powered from AC and voltages of this magnitude. Otherwise they will simply burn out. Therefore, in the body of this light source there is necessarily a board that reduces the voltage and rectifies the current.

The durability of the lamp largely depends on the design of this board. More precisely, what elements are at its input. The cheap ones have nothing except a resistor in front of the rectifying diode bridge. Miracles often happen (usually in lamps from the Middle Kingdom) when even this resistor is not present and the diode bridge is directly connected to the base. Such lamps shine very brightly, but their service life is extremely low if they are not connected through stabilizing devices. For this you can use, for example, ballast transformers.

The most common schemes are those in which a smoothing filter consisting of a resistor and a capacitor is created in the power supply circuit of the lamp control circuit. In the most expensive LED lamps, the power supply and control unit are built on microcircuits. They smooth out stress surges well, but their working life is not too high. Mainly due to the inability to establish effective cooling.

LED board

No matter how hard scientists try, inventing new substances with high radiation efficiency in the visible part of the spectrum, the principle of operation of an LED lamp remains the same, and each of its individual luminous elements is very weak. To achieve the desired effect, they are grouped in groups of several dozen and sometimes hundreds of pieces. For this, a dielectric board is used, on which metal conductive tracks are applied. It is very similar to those used in televisions, computer motherboards and other radio devices.
The LED board performs another important function. As you have already noticed, there is no step-down transformer in the control unit. Of course, it is possible to install it, but this will lead to an increase in the dimensions of the lamp and its cost. The problem of lowering the supply voltage to a nominal value that is safe for the LED is solved simply but extensively. All luminous elements are included in series, like in a Christmas tree garland. For example, if you connect 10 LEDs in series to a 220 volt circuit, then each will get 22 V (however, the current value will remain the same).
The disadvantage of this circuit is that a burnt-out element breaks the entire circuit and the lamp stops shining. In a non-working lamp, out of a dozen LEDs, only one or two may be faulty. There are craftsmen who resolder them and move on with their lives, but most inexperienced users throw the entire device in the trash.

By the way, recycling LED lamps is a separate headache, since they cannot be mixed with ordinary household waste.

Transparent cap

Basically, this element plays the role of protection against dust, moisture and playful hands. However, it also has a utilitarian function. Most LED lamp covers have a matte appearance. This solution might seem strange, since the power of the LED radiation is weakened. But its usefulness for specialists is obvious.

The cap is matte because it inside A layer of phosphor is applied - a substance that begins to glow under the influence of energy quanta. It would seem that here, as they say, oil is oil. But the phosphor has an emission spectrum several times wider than that of an LED. It is close to natural solar. If you leave the LEDs without such a “gasket”, then their glow will make your eyes get tired and hurt.

What are the benefits of such lamps

Now that you already know a lot about how an LED lamp works, it’s worth dwelling on its advantages. The main and indisputable thing is low energy consumption. A dozen LEDs produce the same emission as a traditional incandescent lamp, but at the same time semiconductor devices consume several times less electricity. There is another advantage, but it is not so obvious. Lamps with this operating principle are more durable. True, provided that the supply voltage is as stable as possible.

It is impossible not to mention the disadvantages of such lamps. First of all, this concerns the spectrum of their radiation. It is significantly different from the sun - what the human eye has been accustomed to perceiving for thousands of years. Therefore, for your home, choose those lamps that shine yellow or reddish (warm) and have matte caps.