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Types and types of LEDs - complete classification. LED technical characteristics: power, types Flat LEDs

LEDs have become one of the most common light sources for industrial and domestic needs. This semiconductor device has a single electrical junction; it converts electrical energy into visible light energy. The phenomenon was discovered by Henry Joseph Round in 1907. The first experiments were carried out by the Soviet experimental physicist O.V. Losev, who in 1929 managed to obtain a working prototype of a modern LED.

The first modern LEDs ( SD, LED, LED) were created in the early sixties. They had a faint red glow and were used as power indicators in a variety of devices. In the 90s, blue, yellow, green and white LEDs appeared. Many companies began to produce them on an industrial scale. Today, LED diodes are used everywhere: in traffic lights, light bulbs, cars, and so on.

Device

An LED is a semiconductor device with an electron-hole junction that produces optical radiation when current passes through it in the forward direction.

A standard indicator LED is made of the following parts:

1 - Epoxy lens
2 - Wire contact
3 - Reflector
4 — Semiconductor (Determines the color of the glow)
5 and 6 - Electrodes
7 - Flat cut

The cathode and anode are fixed at the base of the LED. The entire device is hermetically sealed with a lens on top. A crystal is installed on the cathode. The contacts have conductors that are connected to the crystal by a p-n junction (a connecting wire for combining two conductors with different types of conductivity). To create stable operation of the LED, a heat sink is used, which is necessary for lighting devices. In indicator instruments, heat is not of decisive importance.

DIP diodes have leads that are mounted in holes on the printed circuit board; they are connected to an electrical contact by soldering. There are models with several crystals of different colors in one case.

SMD LEDs today are the most popular light sources of any format.

The base of the case, where the crystal is attached, is an excellent heat conductor. Thanks to this, heat removal from the crystal has improved significantly.
In the structure of white LEDs, between the lens and the semiconductor there is a layer of phosphor that neutralizes ultraviolet radiation and sets the required color temperature.
SMD components with a wide radiation angle do not have a lens. At the same time, the LED itself is distinguished by its parallelepiped shape.

Chip-On-Board (COB) represents the latest practical advancement that is poised to take the lead in white LED lighting in artificial lighting.

The design of LEDs using COB technology assumes the following:

Dozens of crystals without a substrate or housing are attached to an aluminum base using dielectric glue.
The resulting matrix is covered with a common layer of phosphor. The result is a light source that has a uniform distribution of luminous flux without the possibility of shadows.

A variation of Chip-On-Board is Chip-On-Glass (COG), a technology that involves placing many small crystals on a glass surface. For example, these are filament lamps, where the emitting element is a glass rod with LEDs coated with phosphor.

Operating principle

Despite the technological features and varieties, the operation of all LEDs is based on the general principle of operation of the emitting element:

The conversion of electricity into light flux is carried out in a crystal, which is made of semiconductors with a wide variety of conductivity types.
A material with n-conductivity is provided by doping it with electrons, and a material with p-conductivity with holes. As a result, additional charge carriers of different directions appear in adjacent layers.
When a direct voltage is applied, the movement of electrons and holes to the p-n junction starts.
The charged particles pass the barrier and begin to recombine, causing an electric current to flow.
The process of recombination of an electron and a hole in the p-n junction zone occurs by releasing energy as a photon.

In general, this physical phenomenon is characteristic of all semiconductor diodes. However, the photon wavelength in most cases lies outside the visible spectrum of radiation. In order for an elementary particle to move in the range of 400-700 nm, scientists conducted many experiments and experiments with different chemical elements. As a result, new compounds appeared: gallium phosphide, gallium arsenide and more complex forms. Each of them has its own wavelength, that is, its own color of radiation.
In addition, in addition to the useful light that the LED emits, a certain amount of heat is generated at the p-n junction, which reduces the efficiency of the semiconductor device. That is why the design of high-power LEDs provides for efficient heat dissipation.

Varieties

Currently, LED diodes can be of the following types:

Lighting, that is, with high power. Their illumination level is equal to tungsten and fluorescent light sources.
Indicator lamps – with low power, they are used for illumination in devices.

LED indicator diodes according to the type of connection are divided into:

Double GaP (gallium, phosphorus) - have green and orange light in the structure of the visible spectrum.
Triple AIGaAs (aluminium, arsenic, gallium) - have yellow and orange light in the structure of the visible spectrum.
Triple GaAsP (arsenic, gallium, phosphorus) - have red and yellow-green light in the structure of the visible spectrum.

Based on the type of housing, LED elements can be:

DIP- an outdated low-power model, they are used to illuminate light boards and toys.
"piranha" or Superflux– analogues of DIP, but with four contacts. They are used for lighting in cars, heat up less and are better attached.
SMD– the most common type, used in a variety of light sources.
COB- These are advanced SMD LEDs.

Application

The applications of LEDs can be divided into two broad categories:

Lighting.
Using direct light.

LED in lighting is used to illuminate an object, space or surface, rather than being directly visible. These are interior lighting, flashlights, lighting of building facades, lighting in cars, backlighting of mobile phone keys and displays, and so on. LED diodes are widely used in communicators and cell phones.

Direct LED light is used to transmit information, for example, in full-color video displays, in which LED diodes form the display pixels, as well as in alphanumeric displays. Direct light is also used in signaling devices. For example, these are turn indicators and brake lights of cars, traffic lights and signs.

The future of LEDs

Scientists are creating a new generation of LEDs, for example, based on nanocrystalline thin films of perovskite. They are cheap, effective and durable. Researchers hope that such LED diodes will be used instead of conventional laptop and smartphone screens, including in household and street lighting.

Fiber LED diodes are also being created, which are intended to create wearable displays. Scientists believe that the created method for producing fiber LEDs will allow for mass production and make the integration of wearable electronics into clothing and textiles completely inexpensive.

Typical characteristics

LEDs are characterized by the following parameters:

Color characteristics.
Wavelength.
Current strength.
Voltage (type of voltage applied).
Brightness (luminous flux intensity).

LED brightness is proportional to the current flowing through it, that is, the higher the voltage, the greater the brightness. The unit of luminous intensity is lumen per steradian and is also measured in millicandelas. There are bright (20-50 mcd.), as well as super bright (20,000 mcd. or more) white LED diodes.

The magnitude of the voltage drop is a characteristic of the permissible values of direct and reverse connections. If the voltage supply is higher than these values, then an electrical breakdown occurs.

The strength of the current determines the brightness of the glow. The current strength of lighting elements is usually 20 mA; for indicator LEDs it is 20-40 mA.

The color of the LED radiation depends on the active substances added to the semiconductor material.

The wavelength of light is determined by the energy difference during the transition of electrons at the recombination stage. It is determined by the doping impurities and the source semiconductor material.

Advantages and disadvantages

Among the advantages of LEDs are:

Low power consumption.
Long service life, measured at 30-100 thousand hours.
High light output. LEDs provide 10-250250 lumens of luminous flux per watt of power.
No toxic mercury vapor.
Wide application.

Flaws:

Poor characteristics of low-quality LEDs created by unknown manufacturers.
Relatively high price of high-quality LEDs.
The need for quality power supplies.

Super-bright LEDs, invented relatively recently, have already become a part of our lives. Compact and economical, they are successfully used both in portable lighting devices and in stationary lighting and illumination systems. Recently, powerful and compact SMD LEDs have become especially popular, which we will talk about today. After reading this article, you will find out why they are called that, how they differ from each other and where they can be found.

Features of SMD LEDs

The main visually noticeable difference between SMD LEDs and conventional ones is the design of their housing:

Conventional with axial leads (left) and SMD LEDs

If a regular diode has leads that are long enough to be mounted through holes in the board, then their SMD analogues have only small contact pads (planar leads) and are mounted directly on the board.

LED mounting in the usual way (left) and surface mounting method

This assembly method is called surface mounting, hence the name of the LEDs: smd (English: Surface Mount Device). This installation is the simplest and can be entrusted to robots.

The assembly of devices using SMD components can be entrusted to a robot

In addition, efficient heat removal from the crystal became possible thanks to the very short but relatively massive pins and the fact that the device practically lies on the board. Indeed, despite their efficiency, super-bright diodes heat up during operation. This design feature made it possible to produce very miniature but powerful SMD LEDs that require good heat dissipation.

Today, the global industry produces many types of SMD LEDs, differing from each other in both dimensions and electrical parameters.

How to decipher the markings

Ultra-bright SMD LEDs are usually labeled with four numbers, and the line of devices produced today looks something like this:

Sizes and appearance of the most popular SMD LEDs

There are, of course, many more types of devices, but these are enough for us to analyze the markings. How to understand this marking and what do the numbers mean? It turns out that there is nothing complicated here: the numbers indicate the horizontal dimensions of the SMD LED housing - length and width in hundredths of a millimeter. For example, the 5050 device has dimensions of 5.0x5.0 mm, and 3528 – 3.5x2.8 mm. The marking does not carry any further information. You can only find out the technical characteristics from the accompanying documentation or take the seller’s word for it.

Expert opinion

Alexey Bartosh

Specialist in repair and maintenance of electrical equipment and industrial electronics.

Ask a question to an expert

When buying LEDs, be sure to read the accompanying documentation - our “friends” from China have a habit of embedding crystals of various powers (usually lower) into a standard package. If the seller is silent about this, then you can easily get an LED with a power of, for example, 0.09 W instead of a one-watt one, but the markings and appearance will be the same!

Brief technical specifications

Although their digital markings do not carry any information about the characteristics of SMD LEDs, there is still some connection between the standard sizes and parameters of the devices. Let's consider the parameters of the most common types of light-emitting SMD semiconductors:

Main technical characteristics of SMD LEDs

Device type	Case dimensions, mm	Number of crystals	Power, W	*Luminous flux, lm**	Operating current, mA	Operating temperature, °C	Solid angle, °	Glow color
3528	3.5x2.8	1 or 3	0.06 or 0.2	0.6 — 5.0*	20	-40 … +85	120 — 140	white, neutral, warm, blue, yellow, green, red, RGB
5050	5.5x1.6	3 or 4	0.2 or 0.26	2 — 14*	60 or 80	-20 … +60	120 — 140	white, warm, blue, yellow, green, red, RGB, RGBW
5630	5.6x3.0	1	0.5	57	150	-25 … +85	120
5730	5.7x3.0	1 or 2	0.5 or 1	50 or 158	150 or 300	-40 … +65	120	cold, white, neutral, warm
3014	3.0x1.4	1	0.12	9 — 11*	30	-40 … +85	120	cold, neutral, warm, blue, yellow, green, red, orange
2835	2.8x3.5	1	0.2 or 0.5 or 1	20 or 50 or 100	60 or 150 or 300	-40 … +65	120	cold, neutral, warm

* - depends on the color of the crystal glow

Now let's look at each of these types in more detail.

smd 3528

This type of smd LED can be single-chip (white, neutral, warm, blue, yellow, green, red) or three-chip (RGB). In the first case, the device has two terminals for connection, in the second - four: one common (cathodes) and three anodes. To protect them from the environment, the crystals are filled with a transparent compound or a compound with the addition of a phosphor that evens out the color characteristics of the diode.

Appearance of single- and triple-chip LED 3528

As can be seen from the plate, this type of LED has a relatively low luminous flux. But thanks to its small size, moderate cost and ability to illuminate in different colors, including RGB, it has still found wide application in inexpensive lighting and decorative lighting devices.

Very often, 3528 LEDs are included in LCD backlight strips. This strip with SMD LEDs is most often used for decorative purposes.

Car lamps and LED strip assembled on 3528

smd 5050

Unlike the 3528, the 5050 is exclusively a three-chip or quad-chip (RGBW) design. If the device is single-color, then all three crystals have the same or close (to equalize the color characteristics) color of light emission. This means that the 5050 diode has three times the brightness of its single-chip counterpart, the smd 3528. As in the first case, the crystals are protected by a compound with or without a phosphor.

Tri-chip LED 5050

This is perhaps the most popular device used for decorative lighting and illumination. It has an optimal cost/power ratio and can provide any backlight color (if using rgb5050), including high-brightness white (four-crystal version), by simply changing the power on each of the crystals.

Most often, such LEDs are built into LED decorative strips such as:

single-channel, where three crystals are connected in parallel and powered by the same voltage;
RGB and RGBW, having three and four channels respectively.

Thanks to the sufficiently high power of the diodes, even at their density of 60 pcs. per 1 meter of LED strip it can be successfully used not only for decorative lighting, but also for interior lighting. At the same time, the user can change the color temperature and even the color of the lighting independently; to do this, it is enough to install the appropriate controller.

LED strips 5050 single color (left), RGB and RGBW

smd 5630 and 5730

The smd 5630 is a single-chip powerful device (see table above) capable of creating a luminous flux of up to 57 lumens. Thanks to the built-in protection assembled on two stabistors, the device is able to withstand pulse current up to 400 mA and polarity reversal. The LED has 4 pins, but only two are involved in the operation of the crystal. The remaining two and the metal substrate are used for better heat dissipation. The LED glow color is white with different color temperatures.

Appearance and internal circuit of the 5630 LED

5730 devices can be either single or dual chip. The former have characteristics similar to the 5630, the latter are twice as powerful (1 W) and are able to create a luminous flux of up to 158 lm.

Appearance of LED 5730

Both types of devices emit white light of different color temperatures and can be used to make powerful LED strips, lamps, and spotlights.

Car lamp at 5630 and a hundred-watt spotlight at 5730

A single-chip compact device of moderate (0.12 W) power and a luminous flux of up to 11 lm. Depending on the version, it can emit white light of different color temperatures, as well as blue, yellow, green, red and orange. To protect from the environment and correct color temperature, the crystal is coated with a compound containing a phosphor.

LED smd 3014

The main area of application of smd 3014: LED strips and modules for decorative lighting, spotlights and lamps for them. Often used to make car lamps.

Car lamp, table and recessed lamps, strip based on SMD 3014 diodes

smd 2835

High power single-chip LED. Available in three versions: 0.2, 0.5 and 1 W. It emits white light of different color temperatures, the body size is the same as the 3528 device, but differs from the latter in the rectangular lens (the 3528 has a round lens).

smd 2835 (left) and smd 3528

Due to the high popularity of devices, a lot of fakes are produced, in which crystals of lower power are installed. So, although the Chinese smd 2835 is officially produced, it is equipped with a crystal of only 0.09 W. Externally, it can be impossible to distinguish it from a one-watt one due to the phosphor added to the compound, since it is opaque, and accordingly, it will not be possible to estimate the dimensions of the crystal by eye.

LEDs are small light bulbs made from semiconductor materials. In the past, they were used as an indicator that showed that the device was turned on. Now developers are providing innovative devices that can be used in various fields. The power of LEDs allows them to be used not only as decoration, but also for room lighting.

Manufacturing process

LEDs are small crystals, they are grown from chemical components. Each of them is installed in a special housing. The process by which the crystal will be made depends on the type of LED. Work order:

Before producing LED lamps or other devices, the LEDs are checked for serviceability. They are tested on special stands.

Variety of LEDs

Before purchasing a product, you need to understand what kind of LEDs there are, where they are used and how the indicated marking is deciphered. They are divided not only by method of application, but also by installation on the circuit board. They can be indicator, lighting and laser. Types of LEDs:

Main characteristics

Before choosing a suitable lamp for lighting, you need to know the basic characteristics of LEDs. This will help achieve the necessary lighting in the room. The main characteristics include operating current, power and voltage, luminous flux level, color temperature, luminous angle and range. What do these characteristics depend on:

Advantages and disadvantages

LED lamps are a new and widely used technology. To determine whether such products are needed in the home, you need to know their advantages and disadvantages. Advantages of diodes:

The biggest disadvantage of LED lamps is their high cost. If we compare them with conventional lamps, their price is 2 times higher. But it quickly pays off.

Although the manufacturer provides a 10-year warranty, this period may be much shorter. This is influenced by manufacturing technology and materials used. Another disadvantage of LED lamps is that they do not fit simple dimers and indicator switches. To eliminate this problem, special lamps are purchased.

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Main characteristics of SMD 5730 LEDs

Modern products with geometric parameters 5.7×3 mm. Due to their stable characteristics, SMD 5730 LEDs belong to the category of ultra-bright products. New materials are used for their manufacture, due to which they have increased power and highly efficient luminous flux. SMD 5730 allows operation in conditions of high humidity. They are not afraid of vibration and temperature fluctuations. They have a long service life. They have a dispersion angle of 120 degrees. After 3000 hours of operation the degree does not exceed 1%.

Manufacturers offer two types of devices: with a power of 0.5 and 1 W. The first are marked SMD 5730-0.5, the second - SMD 5730-1. The device can operate on pulsed current. For SMD 5730-0.5, the rated current is 0.15 A, and when switching to the pulsed operating mode it can reach 0.18 A. It is capable of generating a luminous flux of up to 45 Lm.

For SMD 5730-1, the rated current is 0.35A, pulse current can reach 0.8A with a light output efficiency of 110 Lm. Thanks to the use of heat-resistant polymer in the production process, the device body is not afraid of exposure to fairly high temperatures (up to 250°C).

Cree: current characteristics

The products of the American manufacturer are presented in a wide range. The Xlamp series includes single-chip and multi-chip products. The former are characterized by the distribution of radiation along the edges of the device. This innovative solution made it possible to launch the production of lamps with a large luminous angle with a minimum number of crystals.

The XQ-E High Intensity series is the company's latest development. The products have a glow angle of 100-145 degrees. With relatively small geometric parameters of 1.6 by 1.6 mm, such LEDs have a power of 3 V with a luminous flux of 330 lm. The characteristics of Cree LEDs based on a single crystal make it possible to provide high-quality color rendering CRE 70-90.

Multi-chip LED devices have the latest type of power supply 6-72 V. They are usually divided into three groups depending on the power. Products up to 4 W have 6 crystals and are available in MX and ML packages. The characteristics of the XHP35 LED correspond to a power of 13 W. They have a dispersion angle of 120 degrees. May be warm or cool white.

Checking an LED with a Multimeter

Sometimes it becomes necessary to check the performance of an LED. This can be done using a multimeter. Testing is performed in the following sequence:

Photo	Description of work
	We are preparing the necessary equipment. A regular Chinese multimeter model will do.
	We set the resistance mode corresponding to 200 Ohms.
	We touch the contacts to the element being checked. If the LED is working, it will start to glow.

Attention! If the contacts are swapped, the characteristic glow will not be observed.

LED color marking

To purchase an LED of the desired color, we suggest that you familiarize yourself with the color symbol included in the marking. For CREE, it is located after the designation of a series of LEDs, and can be:

WHT, if the glow is white;
HEW, if high efficiency white;
BWT for white second generation;
B.L.U., if the glow is blue;
GRN for green;
ROY for royal (bright) blue;
RED at red.

Other manufacturers often use a different designation. So KING BRIGHT allows you to choose a model with radiation not only of a certain color, but also of shade. The designation present in the marking will correspond to:

Red (I, SR);
Orange (N, SE);
Yellow (Y);
Blue (PB);
Green (G, SG);
White (PW, MW).

Advice! Read the symbols of a specific manufacturer to make the right choice.

Decoding the LED strip marking code

To manufacture the LED strip, a dielectric with a thickness of 0.2 mm is used. Conductive tracks are applied to it, having contact pads for chips intended for mounting SMD components. The tape includes individual modules 2.5-10 cm long and designed for a voltage of 12 or 24 volts. The module may include 3-22 LEDs and several resistors. The average length of finished products is 5 meters with a width of 8-40 cm.

Markings are applied to the reel or packaging, which contains all the relevant information about the LED strip. The explanation of the markings can be seen in the following figure:

Article

The times when LEDs were used only as indicators for turning on devices are long gone. Modern LED devices can completely replace incandescent lamps in household, industrial and. This is facilitated by the various characteristics of LEDs, knowing which you can choose the right LED analogue. The use of LEDs, given their basic parameters, opens up a wealth of possibilities in the field of lighting.

A light-emitting diode (denoted as LED, LED, LED in English) is a device based on an artificial semiconductor crystal. When an electric current is passed through it, the phenomenon of emission of photons is created, which leads to a glow. This glow has a very narrow spectral range, and its color depends on the semiconductor material.

LEDs with red and yellow emission are made from inorganic semiconductor materials based on gallium arsenide, green and blue ones are made on the basis of indium gallium nitride. To increase the brightness of the luminous flux, various additives are used or the multilayer method is used, when a layer of pure aluminum nitride is placed between semiconductors. As a result of the formation of several electron-hole (p-n) transitions in one crystal, the brightness of its glow increases.

There are two types of LEDs: for indication and lighting. The former are used to indicate the inclusion of various devices in the network, and also as sources of decorative lighting. They are colored diodes placed in a translucent case, each of them has four terminals. Devices emitting infrared light are used in devices for remote control of devices (remote control).

In the lighting area, LEDs are used that emit white light. LEDs are classified by color into cool white, neutral white and warm white. There is a classification of LEDs used for lighting according to the installation method. The SMD LED designation means that the device consists of an aluminum or copper substrate on which the diode crystal is placed. The substrate itself is located in a housing, the contacts of which are connected to the contacts of the LED.

Another type of LED is designated OCB. In such a device, many crystals coated with phosphor are placed on one board. Thanks to this design, a high brightness of the glow is achieved. This technology is used in production with a large luminous flux in a relatively small area. In turn, this makes the production of LED lamps the most accessible and inexpensive.

Note! Comparing lamps based on SMD and COB LEDs, it can be noted that the former can be repaired by replacing a failed LED. If a COB LED lamp does not work, you will have to change the entire board with diodes.

LED characteristics

When choosing a suitable LED lamp for lighting, you should take into account the parameters of the LEDs. These include supply voltage, power, operating current, efficiency (luminous output), glow temperature (color), radiation angle, dimensions, degradation period. Knowing the basic parameters, it will be possible to easily select devices to obtain a particular illumination result.

LED current consumption

As a rule, a current of 0.02A is provided for conventional LEDs. However, there are LEDs rated at 0.08A. These LEDs include more powerful devices, the design of which involves four crystals. They are located in one building. Since each of the crystals consumes 0.02A, in total one device will consume 0.08A.

The stability of LED devices depends on the current value. Even a slight increase in current helps to reduce the radiation intensity (aging) of the crystal and increase the color temperature. This ultimately leads to the LEDs turning blue and failing prematurely. And if the current increases significantly, the LED immediately burns out.

To limit the current consumption, the designs of LED lamps and luminaires include current stabilizers for LEDs (drivers). They convert the current, bringing it to the value required by the LEDs. In the case when you need to connect a separate LED to the network, you need to use current-limiting resistors. The resistor resistance for an LED is calculated taking into account its specific characteristics.

Helpful advice! To choose the right resistor, you can use the LED resistor calculator available on the Internet.

LED voltage

How to find out the LED voltage? The fact is that LEDs do not have a supply voltage parameter as such. Instead, the voltage drop characteristic of the LED is used, which means the amount of voltage the LED outputs when the rated current passes through it. The voltage value indicated on the packaging reflects the voltage drop. Knowing this value, you can determine the voltage remaining on the crystal. It is this value that is taken into account in the calculations.

Given the use of various semiconductors for LEDs, the voltage for each of them may be different. How to find out how many volts an LED is? You can determine it by the color of the devices. For example, for blue, green and white crystals the voltage is about 3V, for yellow and red crystals it is from 1.8 to 2.4V.

When using a parallel connection of LEDs of identical ratings with a voltage value of 2V, you may encounter the following: as a result of variations in parameters, some emitting diodes will fail (burn out), while others will glow very faintly. This will happen due to the fact that when the voltage increases even by 0.1V, the current passing through the LED increases by 1.5 times. Therefore, it is so important to ensure that the current matches the LED rating.

Light output, beam angle and LED power

The luminous flux of diodes is compared with other light sources, taking into account the strength of the radiation they emit. Devices measuring about 5 mm in diameter produce from 1 to 5 lumens of light. While the luminous flux of a 100W incandescent lamp is 1000 lm. But when comparing, it is necessary to take into account that a regular lamp has diffused light, while an LED has directional light. Therefore, the dispersion angle of the LEDs must be taken into account.

The scattering angle of different LEDs can range from 20 to 120 degrees. When illuminated, LEDs produce brighter light in the center and reduce illumination towards the edges of the dispersion angle. Thus, LEDs illuminate a specific space better while using less power. However, if it is necessary to increase the illumination area, diverging lenses are used in the design of the lamp.

How to determine the power of LEDs? To determine the power of an LED lamp required to replace an incandescent lamp, it is necessary to apply a coefficient of 8. Thus, you can replace a conventional 100W lamp with an LED device with a power of at least 12.5W (100W/8). For convenience, you can use the data from the table of correspondence between the power of incandescent lamps and LED light sources:

Incandescent lamp power, W	Corresponding power of LED lamp, W
100	12-12,5
75	10
60	7,5-8
40	5
25	3

When using LEDs for lighting, the efficiency indicator is very important, which is determined by the ratio of luminous flux (lm) to power (W). Comparing these parameters for different light sources, we find that the efficiency of an incandescent lamp is 10-12 lm/W, a fluorescent lamp is 35-40 lm/W, and an LED lamp is 130-140 lm/W.

Color temperature of LED sources

One of the important parameters of LED sources is the glow temperature. The units of measurement for this quantity are degrees Kelvin (K). It should be noted that all light sources are divided into three classes according to their glow temperature, among which warm white has a color temperature of less than 3300 K, daylight white - from 3300 to 5300 K, and cool white over 5300 K.

Note! The comfortable perception of LED radiation by the human eye directly depends on the color temperature of the LED source.

The color temperature is usually indicated on the labeling of LED lamps. It is designated by a four-digit number and the letter K. The choice of LED lamps with a certain color temperature directly depends on the characteristics of its use for lighting. The table below displays options for using LED sources with different glow temperatures:

LED color		Color temperature, K	Lighting Use Cases
White	Warm	2700-3500	Lighting for domestic and office premises as the most suitable analogue of an incandescent lamp
	Neutral (daytime)	3500-5300	The excellent color rendition of such lamps allows them to be used for lighting workplaces in production.
	Cold	over 5300	Mainly used for street lighting, and also used in hand-held lanterns
Red		1800	As a source of decorative and phyto-lighting
Green		-
Yellow		3300	Lighting design of interiors
Blue		7500	Illumination of surfaces in the interior, phyto-lighting

The wave nature of color allows the color temperature of LEDs to be expressed using wavelength. The marking of some LED devices reflects the color temperature precisely in the form of an interval of different wavelengths. The wavelength is designated λ and is measured in nanometers (nm).

Standard sizes of SMD LEDs and their characteristics

Considering the size of SMD LEDs, devices are classified into groups with different characteristics. The most popular LEDs with standard sizes are 3528, 5050, 5730, 2835, 3014 and 5630. The characteristics of SMD LEDs vary depending on the size. Thus, different types of SMD LEDs differ in brightness, color temperature, and power. In LED markings, the first two digits indicate the length and width of the device.

Basic parameters of SMD 2835 LEDs

The main characteristics of SMD LEDs 2835 include an increased radiation area. Compared to the SMD 3528 device, which has a round working surface, the SMD 2835 radiation area has a rectangular shape, which contributes to greater light output with a smaller element height (about 0.8 mm). The luminous flux of such a device is 50 lm.

The SMD 2835 LED housing is made of heat-resistant polymer and can withstand temperatures up to 240°C. It should be noted that the radiation degradation in these elements is less than 5% over 3000 hours of operation. In addition, the device has a fairly low thermal resistance of the crystal-substrate junction (4 C/W). The maximum operating current is 0.18A, the crystal temperature is 130°C.

Based on the color of the glow, there are warm white with a glow temperature of 4000 K, daytime white - 4800 K, pure white - from 5000 to 5800 K and cool white with a color temperature of 6500-7500 K. It is worth noting that the maximum luminous flux is for devices with cool white glow, the minimum is for warm white LEDs. The design of the device has enlarged contact pads, which promotes better heat dissipation.

Helpful advice! SMD 2835 LEDs can be used for any type of installation.

Characteristics of SMD 5050 LEDs

The SMD 5050 housing design contains three LEDs of the same type. LED sources of blue, red and green colors have technical characteristics similar to SMD 3528 crystals. The operating current of each of the three LEDs is 0.02A, therefore the total current of the entire device is 0.06A. To ensure that the LEDs do not fail, it is recommended not to exceed this value.

LED devices SMD 5050 have a forward voltage of 3-3.3V and a light output (mains flux) of 18-21 lm. The power of one LED is the sum of three power values of each crystal (0.7 W) and amounts to 0.21 W. The color of the glow emitted by the devices can be white in all shades, green, blue, yellow and multi-colored.

The close arrangement of LEDs of different colors in one SMD 5050 package made it possible to implement multi-color LEDs with separate control of each color. To regulate luminaires using SMD 5050 LEDs, controllers are used, so that the color of the glow can be smoothly changed from one to another after a given amount of time. Typically, such devices have several control modes and can adjust the brightness of the LEDs.

Typical characteristics of SMD 5730 LED

SMD 5730 LEDs are modern representatives of LED devices, the housing of which has geometric dimensions of 5.7x3 mm. They belong to ultra-bright LEDs, the characteristics of which are stable and qualitatively different from the parameters of their predecessors. Manufactured using new materials, these LEDs are characterized by increased power and highly efficient luminous flux. In addition, they can work in conditions of high humidity, are resistant to temperature changes and vibration, and have a long service life.

There are two types of devices: SMD 5730-0.5 with a power of 0.5 W and SMD 5730-1 with a power of 1 W. A distinctive feature of the devices is the ability to operate on pulsed current. The rated current of SMD 5730-0.5 is 0.15A; during pulse operation, the device can withstand current up to 0.18A. This type of LEDs provides a luminous flux of up to 45 lm.

SMD 5730-1 LEDs operate at a constant current of 0.35A, in pulsed mode - up to 0.8A. The light output efficiency of such a device can be up to 110 lm. Thanks to the heat-resistant polymer, the device body can withstand temperatures up to 250°C. The dispersion angle of both types of SMD 5730 is 120 degrees. The degree of luminous flux degradation is less than 1% when operating for 3000 hours.

Cree LED Specifications

The Cree company (USA) is engaged in the development and production of ultra-bright and most powerful LEDs. One of the Cree LED groups is represented by the Xlamp series of devices, which are divided into single-chip and multi-chip. One of the features of single-crystal sources is the distribution of radiation along the edges of the device. This innovation made it possible to produce lamps with a large luminous angle using a minimum number of crystals.

In the XQ-E High Intensity series of LED sources, the beam angle ranges from 100 to 145 degrees. Having small geometric dimensions of 1.6x1.6 mm, the power of ultra-bright LEDs is 3 Volts, and the luminous flux is 330 lm. This is one of the newest developments from Cree. All LEDs, the design of which is developed on the basis of a single crystal, have high-quality color rendering within CRE 70-90.

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How to make or repair an LED garland yourself. Prices and main characteristics of the most popular models.

Cree has released several versions of multi-chip LED devices with the latest power types from 6 to 72 Volts. Multichip LEDs are divided into three groups, which include devices with high voltage, power up to 4W and above 4W. Sources up to 4W contain 6 crystals in MX and ML type housings. The dispersion angle is 120 degrees. You can buy Cree LEDs of this type with white warm and cool colors.

Helpful advice! Despite the high reliability and quality of light, you can buy powerful LEDs of the MX and ML series at a relatively low price.

The group over 4W includes LEDs made from several crystals. The largest in the group are the 25W devices represented by the MT-G series. The company's new product is XHP model LEDs. One of the large LED devices has a 7x7 mm body, its power is 12W, and the light output is 1710 lm. High voltage LEDs combine small dimensions and high light output.

LED connection diagrams

There are certain rules for connecting LEDs. Taking into account that the current passing through the device moves only in one direction, for long-term and stable operation of LED devices it is important to take into account not only a certain voltage, but also the optimal current value.

Connection diagram for LED to 220V network

Depending on the power source used, there are two types of circuits for connecting LEDs to 220V. In one of the cases it is used with limited current, in the second - a special one that stabilizes the voltage. The first option takes into account the use of a special source with a certain current strength. A resistor is not required in this circuit, and the number of connected LEDs is limited by the driver power.

To designate LEDs in the diagram, two types of pictograms are used. Above each schematic image there are two small parallel arrows pointing upward. They symbolize the bright glow of the LED device. Before connecting the LED to 220V using a power supply, you must include a resistor in the circuit. If this condition is not met, this will lead to the fact that the working life of the LED will be significantly reduced or it will simply fail.

If you use a power supply when connecting, then only the voltage in the circuit will be stable. Considering the insignificant internal resistance of an LED device, turning it on without a current limiter will lead to the device burning out. That is why a corresponding resistor is introduced into the LED switching circuit. It should be noted that resistors come in different values, so they must be calculated correctly.

Helpful advice! The negative aspect of circuits for connecting an LED to a 220 Volt network using a resistor is the dissipation of high power when it is necessary to connect a load with increased current consumption. In this case, the resistor is replaced with a quenching capacitor.

How to calculate the resistance for an LED

When calculating the resistance for an LED, they are guided by the formula:

U = IxR,

where U is voltage, I is current, R is resistance (Ohm’s law). Let's say you need to connect an LED with the following parameters: 3V - voltage and 0.02A - current. So that when connecting an LED to 5 Volts on the power supply it does not fail, you need to remove the extra 2V (5-3 = 2V). To do this, you need to include a resistor with a certain resistance in the circuit, which is calculated using Ohm’s law:

R = U/I.

Thus, the ratio of 2V to 0.02A will be 100 Ohms, i.e. This is exactly the resistor needed.

It often happens that, given the parameters of the LEDs, the resistance of the resistor has a value that is non-standard for the device. Such current limiters cannot be found at points of sale, for example, 128 or 112.8 ohms. Then you should use resistors whose resistance is the closest value compared to the calculated one. In this case, the LEDs will not function at full capacity, but only at 90-97%, but this will be invisible to the eye and will have a positive effect on the life of the device.

There are many options for LED calculation calculators on the Internet. They take into account the main parameters: voltage drop, rated current, output voltage, number of devices in the circuit. By specifying the parameters of LED devices and current sources in the form field, you can find out the corresponding characteristics of resistors. To determine the resistance of color-coded current limiters, there are also online calculations of resistors for LEDs.

Schemes for parallel and serial connection of LEDs

When assembling structures from several LED devices, circuits for connecting LEDs to a 220 Volt network with a serial or parallel connection are used. At the same time, for correct connection, it should be taken into account that when LEDs are connected in series, the required voltage is the sum of the voltage drops of each device. While when LEDs are connected in parallel, the current strength is added up.

If the circuits use LED devices with different parameters, then for stable operation it is necessary to calculate the resistor for each LED separately. It should be noted that no two LEDs are exactly alike. Even devices of the same model have minor differences in parameters. This leads to the fact that when a large number of them are connected in a series or parallel circuit with one resistor, they can quickly degrade and fail.

Note! When using one resistor in a parallel or series circuit, you can only connect LED devices with identical characteristics.

The discrepancy in parameters when connecting several LEDs in parallel, say 4-5 pieces, will not affect the operation of the devices. But if you connect a lot of LEDs to such a circuit, it will be a bad decision. Even if LED sources have a slight variation in characteristics, this will cause some devices to emit bright light and burn out quickly, while others will glow dimly. Therefore, when connecting in parallel, you should always use a separate resistor for each device.

As for the series connection, there is economical consumption here, since the entire circuit consumes an amount of current equal to the consumption of one LED. In a parallel circuit, the consumption is the sum of the consumption of all LED sources included in the circuit.

How to connect LEDs to 12 Volts

In the design of some devices, resistors are provided at the manufacturing stage, which makes it possible to connect LEDs to 12 Volts or 5 Volts. However, such devices cannot always be found on sale. Therefore, in the circuit for connecting LEDs to 12 volts, a current limiter is provided. The first step is to find out the characteristics of the connected LEDs.

Such a parameter as the forward voltage drop for typical LED devices is about 2V. The rated current of these LEDs corresponds to 0.02A. If you need to connect such an LED to 12V, then the “extra” 10V (12 minus 2) must be extinguished with a limiting resistor. Using Ohm's law you can calculate the resistance for it. We get that 10/0.02 = 500 (Ohm). Thus, a resistor with a nominal value of 510 Ohms is required, which is the closest in the range of E24 electronic components.

In order for such a circuit to work stably, it is also necessary to calculate the power of the limiter. Using the formula based on which power is equal to the product of voltage and current, we calculate its value. We multiply a voltage of 10V by a current of 0.02A and get 0.2W. Thus, a resistor is required, the standard power rating of which is 0.25W.

If it is necessary to include two LED devices in the circuit, then it should be taken into account that the voltage dropped across them will already be 4V. Accordingly, the resistor will have to extinguish not 10V, but 8V. Consequently, further calculation of the resistance and power of the resistor is done based on this value. The location of the resistor in the circuit can be provided anywhere: on the anode side, cathode side, between the LEDs.

How to test an LED with a multimeter

One way to check the operating condition of LEDs is to test with a multimeter. This device can diagnose LEDs of any design. Before checking the LED with a tester, the device switch is set in the “testing” mode, and the probes are applied to the terminals. When the red probe is connected to the anode and the black probe to the cathode, the crystal should emit light. If the polarity is reversed, the device display should display “1”.

Helpful advice! Before testing the LED for functionality, it is recommended to dim the main lighting, since during testing the current is very low and the LED will emit light so weakly that in normal lighting it may not be noticeable.

Testing LED devices can be done without using probes. To do this, insert the anode into the holes located in the lower corner of the device into the hole with the symbol “E”, and the cathode into the hole with the indicator “C”. If the LED is in working condition, it should light up. This testing method is suitable for LEDs with sufficiently long contacts that have been cleared of solder. The position of the switch does not matter with this method of checking.

How to check LEDs with a multimeter without desoldering? To do this, you need to solder pieces of a regular paper clip to the tester probes. A textolite gasket, which is placed between the wires and then treated with electrical tape, is suitable as insulation. The output is a kind of adapter for connecting probes. The clips spring well and are securely fixed in the connectors. In this form, you can connect the probes to the LEDs without removing them from the circuit.

What can you make from LEDs with your own hands?

Many radio amateurs practice assembling various designs from LEDs with their own hands. Self-assembled products are not inferior in quality, and sometimes even surpass their manufactured counterparts. These can be color and music devices, flashing LED designs, do-it-yourself LED running lights and much more.

DIY current stabilizer assembly for LEDs

To prevent the LED's life from being exhausted ahead of schedule, it is necessary that the current flowing through it has a stable value. It is known that red, yellow and green LEDs can cope with increased current load. While blue-green and white LED sources, even with a slight overload, burn out in 2 hours. Thus, for the LED to operate normally, it is necessary to resolve the issue with its power supply.

If you assemble a chain of series- or parallel-connected LEDs, you can provide them with identical radiation if the current passing through them has the same strength. In addition, reverse current pulses can negatively affect the life of LED sources. To prevent this from happening, it is necessary to include a current stabilizer for the LEDs in the circuit.

The qualitative characteristics of LED lamps depend on the driver used - a device that converts voltage into a stabilized current with a specific value. Many radio amateurs assemble a 220V LED power supply circuit with their own hands based on the LM317 microcircuit. The elements for such an electronic circuit are low cost and such a stabilizer is easy to construct.

When using a current stabilizer on LM317 for LEDs, the current is adjusted within 1A. A rectifier based on LM317L stabilizes the current to 0.1A. The device circuit uses only one resistor. It is calculated using an online LED resistance calculator. Available devices are suitable for power supply: power supplies from a printer, laptop or other consumer electronics. It is not profitable to assemble more complex circuits yourself, since they are easier to purchase ready-made.

DIY LED DRLs

The use of daytime running lights (DRLs) on cars significantly increases the visibility of the car during daylight hours by other road users. Many car enthusiasts practice self-assembly of DRLs using LEDs. One of the options is a DRL device of 5-7 LEDs with a power of 1W and 3W for each block. If you use less powerful LED sources, the luminous flux will not meet the standards for such lights.

Helpful advice! When making DRLs with your own hands, take into account the requirements of GOST: luminous flux 400-800 cd, luminous angle in the horizontal plane - 55 degrees, in the vertical plane - 25 degrees, area - 40 cm².

For the base, you can use a board made of aluminum profile with pads for mounting LEDs. The LEDs are fixed to the board using a thermally conductive adhesive. Optics are selected according to the type of LED sources. In this case, lenses with a luminous angle of 35 degrees are suitable. Lenses are installed on each LED separately. The wires are routed in any convenient direction.

Next, a housing is made for the DRLs, which also serves as a radiator. For this you can use a U-shaped profile. The finished LED module is placed inside the profile, secured with screws. All free space can be filled with transparent silicone-based sealant, leaving only the lenses on the surface. This coating will serve as a moisture barrier.

Connecting the DRL to the power supply requires the mandatory use of a resistor, the resistance of which is pre-calculated and tested. Connection methods may vary depending on the car model. Connection diagrams can be found on the Internet.

How to make LEDs blink

The most popular flashing LEDs, which can be purchased ready-made, are devices that are controlled by the potential level. The blinking of the crystal occurs due to a change in power supply at the terminals of the device. Thus, a two-color red-green LED device emits light depending on the direction of the current passing through it. The blinking effect in the RGB LED is achieved by connecting three separate control pins to a specific control system.

But you can make an ordinary single-color LED blink, having a minimum of electronic components in your arsenal. Before you make a flashing LED, you need to choose a working circuit that is simple and reliable. You can use a flashing LED circuit, which will be powered from a 12V source.

The circuit consists of a low-power transistor Q1 (silicon high-frequency KTZ 315 or its analogues are suitable), a resistor R1 820-1000 Ohms, a 16-volt capacitor C1 with a capacity of 470 μF and an LED source. When the circuit is turned on, the capacitor is charged to 9-10V, after which the transistor opens for a moment and transfers the accumulated energy to the LED, which begins to blink. This circuit can only be implemented when powered from a 12V source.

You can assemble a more advanced circuit that works in a similar way to a transistor multivibrator. The circuit includes transistors KTZ 102 (2 pcs.), resistors R1 and R4 of 300 Ohms each to limit the current, resistors R2 and R3 of 27000 Ohms each to set the base current of the transistors, 16-volt polar capacitors (2 pcs. with a capacity of 10 uF) and two LED sources. This circuit is powered by a 5V DC voltage source.

The circuit operates on the “Darlington pair” principle: capacitors C1 and C2 are alternately charged and discharged, which causes a particular transistor to open. When one transistor supplies energy to C1, one LED lights up. Next, C2 is smoothly charged, and the base current of VT1 is reduced, which leads to the closing of VT1 and the opening of VT2 and another LED lights up.

Helpful advice! If you use a supply voltage above 5V, you will need to use resistors with a different value to prevent failure of the LEDs.

DIY LED color music assembly

To implement fairly complex color music circuits on LEDs with your own hands, you must first understand how the simplest color music circuit works. It consists of one transistor, a resistor and an LED device. Such a circuit can be powered from a source rated from 6 to 12V. The operation of the circuit occurs due to cascade amplification with a common radiator (emitter).

The VT1 base receives a signal with varying amplitude and frequency. When signal fluctuations exceed a specified threshold, the transistor opens and the LED lights up. The disadvantage of this scheme is the dependence of blinking on the degree of the sound signal. Thus, the effect of color music will appear only at a certain level of sound volume. If you increase the sound. The LED will be on all the time, and when it decreases, it will flash slightly.

To achieve a full effect, they use a color music circuit using LEDs, dividing the sound range into three parts. The circuit with a three-channel audio converter is powered from a 9V source. A huge number of color music schemes can be found on the Internet at various amateur radio forums. These can be color music schemes using a single-color strip, an RGB LED strip, as well as a scheme for smoothly switching LEDs on and off. You can also find diagrams of running LED lights online.

DIY LED voltage indicator design

The voltage indicator circuit includes resistor R1 (variable resistance 10 kOhm), resistors R1, R2 (1 kOhm), two transistors VT1 KT315B, VT2 KT361B, three LEDs - HL1, HL2 (red), HLЗ (green). X1, X2 – 6-volt power supplies. In this circuit, it is recommended to use LED devices with a voltage of 1.5V.

The operating algorithm of a homemade LED voltage indicator is as follows: when voltage is applied, the central green LED source lights up. In the event of a voltage drop, the red LED located on the left turns on. An increase in voltage causes the red LED on the right to light up. With the resistor in the middle position, all transistors will be in the closed position, and voltage will only flow to the central green LED.

Transistor VT1 opens when the resistor slider is moved up, thereby increasing the voltage. In this case, the voltage supply to HL3 stops, and it is supplied to HL1. When the slider moves down (voltage decreases), transistor VT1 closes and VT2 opens, which will provide power to the LED HL2. With a slight delay, LED HL1 will go out, HL3 will flash once and HL2 will light up.

Such a circuit can be assembled using radio components from outdated equipment. Some assemble it on a textolite board, observing a 1:1 scale with the dimensions of the parts so that all elements can fit on the board.

The limitless potential of LED lighting makes it possible to independently design various lighting devices from LEDs with excellent characteristics and a fairly low cost.