Laboratory work №2. I was very interested in how the "efficiency" of the LED depends on the current that passes through it. I'll try to find the point of highest efficiency. Well, as usual, I will share my craft. Complete analysis of 1W LED Bulbs. Who cares, let's go.
First, let's see how the package arrived. 
Standard package with bubble wrap inside. 
Everything is packaged to the highest standard. 
Who cares, all the characteristics are written on the package. 
Exactly 100pcs. Received a long time ago. For more than three months they lay idle. Picked mostly with light bulbs. It came to them as well. I decided to build a graph of the dependence of the "brightness of the glow" on the current and power on the LED. There were many questions about this. I decided to close the gap with an experiment.
In the experiment, this device with a built-in luxmeter will help me. Allows you to measure the level of illumination up to 4000 - 40000 Lux (± 5.0%). This is what it looks like on the official website. 
And this is how he is in real life. 
To minimize the error, we curtain the windows. The distance to the LED is about 30cm. This value does not affect the experiment, because we are interested in dependence, not absolute values. Luxmeter shows 3 Lux. The light background at 3 Lux will not affect the measurement accuracy. I will use the Calibrator P321 as a source of stabilized current.
The P321 current calibrator with manual and program control is designed for use in automated testing facilities, as well as an independent device for testing analog and digital devices at direct current.The principle is simple. I apply an exemplary current from the calibrator to the LED, while measuring the voltage on the LED (since the voltage will increase as the current increases) and the illumination. All the data was summarized in a table. The rest of the data in the table are obtained by calculation (multiplication and division of the measured values). This is necessary to obtain more descriptive figures.
> Using the resulting table, I will plot the dependence of the "energy efficiency" of the LED on the power (current) that was passed through it. Many guessed about such dependence. I made it into a graph. 
As we can see from the graph, the higher the power passing through the LED, the lower the "energy efficiency". If you try to say it simply, the less power from the nominal value, the more power goes into light, and not into heat. I guessed about such dependence. Now confirmed with the help of measurements.
If you follow the logic of the experiment when replacing 1W LEDs in an LED light bulb with 3W LEDs, it will shine almost 1.5 times brighter for the same power consumption! And there will be less heat! (Other things being equal).
This completes the laboratory work. The work is done, the conclusion is made. Let's move on to practical exercises.
With the help of these LEDs, I decided to remake the lamp. 
The light bulbs have already deteriorated, and the new ones are of poor quality. 
I took foil textolite. 
Didn't charge a fee. Just cut grooves (faster this way). 
From above, the board was covered with spray paint. I made the board so that it could be connected both to an electronic driver and to a driver on conduits (when soldering jumpers in a certain way). 
The diodes with the board will be pressed against the aluminum sheet. I drank from what I found. 
Soldered diodes. Jumpers set to connect the electronic driver according to the scheme. 
Driver for 600mA, 9-12V. 
Let's measure the current and voltage. 
The pictures didn't come out very well. Weak lighting, so it focuses badly (sorry). 
This is secondary. 0.57A*9.55V=5.44W. Let's see how much it consumes from the network.
6.46W. The difference is 1W, this is taken over by the driver.
I decided to connect the lamp through conduits, I don’t need a lot of power, but I’ll save the electronic driver for something more worthwhile. And here is the diagram. 
I solder the jumpers differently. 
All diodes are in series.
I also made a board for the driver from what was (quickly) 
There was even a pin for fastening. Throttle did not clean up. Left for weight, otherwise the lamp will fall. 
Made according to all the rules of electrical safety. Not a single element under voltage comes out. The board is fixed with printed conductors inside.
Additional Information
And, as usual, let's see how it shines. 
This is a 40W light bulb. Naturally, all the bulbs are in equal conditions (shutter speed on the handbrake, the distance to the wall is the same). 
This is my LED lamp. The photoexposure meter suggests that it shines brighter than forty.
The estimated power of the lamp is 3.9W. The area of the aluminum sheet is 42.3 cm2. It turns out 11 cm2 per watt. Almost does not heat up. For comparison, purchased LED light bulbs with a power of 1.3W have an area of 7cm2 (5.5cm2 per watt) on PCB, they work for six months without breakdowns.
And in the end, for those who like to track tracks.
Many people have a question why a diode of the same power (for example, 50W) costs 100 rubles in a Chinese online store, and 500 rubles in Russia. Chinese sellers and manufacturers are making good use of the characteristics of LEDs that cannot be measured without special equipment. In addition, they learned to produce very cheap and low-quality ones. 99% of buyers do not understand them and encounter them for the first time. A big difference in price gives a good reason for deception, you can always sell junk at the price of a branded one, which they skillfully do.
You probably saw that sometimes the seller writes the size of the crystal in the characteristics, indicating it in "mil". This is how thousandths of an inch are indicated, in millimeters it turns out 0.0254 mm. A typical crystal has dimensions of 30*30mil and 45*45mil. In millimeters 0.762 * 0.762mm and 1.143 * 1.143mm. It is not very easy to measure, but you can compare by eye if there is a standard. I use a digital caliper, accurate to 0.01mm. For measurements, you need a tool with sharp ends, a regular micrometer is not suitable, since the crystal is recessed into the case.
Correspondence of sizes and power:
On LED matrices, power can be found by the number of installed CDs. They are visible as dots under the yellow phosphor. Color and RGB do not have a phosphor, they can be seen perfectly.
On powerful LEDs 1 KR has a power of 1W and a rated current of 300mA. At this current, regular long-term operation is ensured. If 50 CR are visible, then 50W will be respectively equal.
Consider the features of high-power LED matrices of white light. To reduce the cost, the Chinese decided to install smaller and worse crystals by 0.5W and 0.75W, for which the rated current is 150mA and 220mA. For them, 300mA will be too much, they will degrade and heat up a lot. Good ones should be between 30*30mil and 45*45mil in length and width.
When making a choice in a store, use this information to calculate the actual parameters of powerful matrices from 10W, 20W, 30W, 50W, 70W, 100W.
To visually determine the quality of a high power LED, use geometric parameters. It is best if the chips under the phosphor are square. Rectangular is practically a guarantee of overestimated performance.
The numbers in the marking indicate only the size of the SMD case. And it has nothing to do with its power. For example, for SMD5050, the dimensions will be 5.0mm by 5.0mm.
In large SMD5630, SMD 5730 cases, European and American brands Samsung, LG, Philips produce 0.5W ice chips. The Chinese skillfully use this, and put a weak KR at 0.01W in the standard case 5630 and 5730, selling them as 0.5W. Therefore, Chinese corn lamps are studded with weak diodes.
In addition to manufacturing low-quality LEDs, the Chinese have learned to produce fakes of super-bright LEDs for flashlights, LED beams, and bicycle lights. They copy the appearance by 95-99%, but the parameters still remain Chinese, 30-40% worse than the originals.
This explains the low cost of rechargeable LED lights for Cree Q5, Cree XML T6, Cree XHP50. The cheapest ones are 100% fake. I personally checked it, having bought 10 different flashlights on Kriya Q5 and T6. All of them ended up on fake CREEs produced by LatticeBright.
The characteristics of bright LEDs for flashlights are described in detail at the links:
There are many options to reduce its cost, to replace expensive materials with cheap ones. The most important feature is that such a replacement does not affect the appearance in any way, which is why such questions arise.
List of differences affecting the price:
Some parameters can only be determined after 5000 h. works:
I believe that the effective period of service according to the L80 and L70 standards plays a paramount role in the payback. For street LED lamps, secondary parameters do not play a special role.
1. On cheap LEDs, the base is made of aluminum, its thermal conductivity is worse than that of copper. This greatly affects the mass. The rate of heat removal from the RR decreases, during operation their temperature becomes higher.
2. The crystal has very small dimensions, for power supply it is connected by thin conductors to external contacts. Best if there are 4 of them, worst of all 2 pieces.
3. In branded diodes, the conductors are made of thin gold threads, they can withstand current surges, especially in a car. Gold is replaced with copper or gilded copper. Probably many of you have seen daytime running lights or LED lamps that flash. When heated, contact with Kp is lost, when cooled, it appears again.
4. Copper is much heavier than aluminum or other alloys based on it. Therefore, a good LED should be heavy. For low power 1W, 3W, 5W, the difference will be small. And starting from 10W to 100W, the difference in weight will be 2-3 times.
5. The L70 and L80 standard define the number of hours that it will work before the luminous flux drops to 70% and 80% of the original. The Chinese write for everyone the standard value of 30,000 hours. and 50.000h.
6. According to the characteristics, the LEDs have a maximum operating temperature of 60°. Already 70 ° are critical for them, a large cooling system is required. Good ones will work for the prescribed time of 50-70 thousand hours at 110 °.
7. The worst ones give 50 lm/w, the good ones up to 130 lm/w, the best ones up to 200 lm/w. When buying from the Chinese, do not expect that there will be more than 100 lm / watt.
8. All white ice chips without phosphor glow blue. To give it a warm white or neutral white color, yellow phosphor is applied. It is different, inexpensive quickly burns out. This results in a color shift towards blue and a change in the color rendering index. A CRI below 80 is not suitable for residential use.
9. Color reproduction is responsible for the accuracy of the colors of the object that we see under LED lighting. With low CRI<80 цвета будут сильно искажены, поэтому светодиодные светильники и лампы с CRI <80 используют в уличном освещении, в подсобных и нежилых помещениях.
10. The current strength that can be applied to it depends on the size of the CR. Square LED COB matrices (assemblies, modules) consist of conventional 1W and 3W crystals. For them, the standard 30mil, 45mil. For 10W, 20W, 30W, 50W, 100W high power COB LEDs, the sizes can be 24*24mil, 24*44mil, 44*44mil.
For low-power LEDs, they can be of different sizes, even 2-3 CRs in one package, connected in series or in parallel.
11. The same applies to powerful RGB LEDs. The dimensions of the KR for 1W and 3W can be the same. Bad ones are labeled as 1W, which are better labeled 3W.
12. Indirectly, the quality can be found by the spread of the parameters of the used CR. They are turned on so that they glow slightly. Some will shine much brighter than others, this is a big spread. The more evenly they shine, the better.
13. The quality of the assembly and installation of the KR affects the service life. All elements are subjected to strong heating and cooling, materials expand and contract. If the heat removal deteriorates, then the phosphor begins to blacken near it.
A 1 watt LED is an example of a powerful light source. The number of its sales is increasing as people realize all the benefits of using an LED fixture.
Advantages of a powerful 1 watt LED:
Using LED sources with a power of 1 watt, you can create energy-saving lighting systems. After all, one such lighting device replaces several incandescent lamps. In addition, it does not contain components harmful to health and does not require high disposal costs.
One of the problems in the manufacture of high-power LEDs for 1 W, 3 W, etc. is the issue of heat dissipation. The radiating semiconductor is very afraid of overheating, so during its operation it is necessary to provide cooling.
Heat is removed by fixing the LED on a special radiator - a flat aluminum substrate, the temperature of which should not exceed 45 degrees. The substrate helps to simplify installation, since it is convenient to make holes in it for fastening and it is convenient to solder it.
With regular overheating of the LED by 1 W, its service life is reduced. If you purchased a crystal without a substrate and are going to mount it yourself, then it is recommended to choose an aluminum panel with an area of 25 cm2. or more. This is a 5x5mm plate. It is desirable that air circulate around it at least a little.
The voltage drop across a powerful 1W white light LED is typically 3-3.5 volts. Power is gained due to the increased current up to 300-350 mA. To ensure proper power supply, LEDs are assembled in circuits with a resistor or connected through drivers. The task when assembling the circuit is to ensure a stable voltage and current, which would not exceed the maximum allowable value.
The most popular are powerful 1W LEDs for surface mounting. There is their release option "on a star". This is a heat sink plate made in the shape of a star. It has pads for contacts, so working with this design is very convenient.
Among light temperatures, daylight white, soft white and bluish tints are preferred, although there are models on the market that emit a variety of shades of blue and yellow-red, as well as green light.
Color rendering is very high (more than 80%). The luminous flux can reach 100 lumens, which is equivalent to the luminous flux from a 15 watt incandescent lamp.
Modern 1-watt models are used to illuminate furniture, interiors in cars and buses, for indoor and outdoor lighting of housing. They are inserted into high-impact flashlights that can run on conventional batteries.
Sometimes there are negative reviews about LEDs, which write about low light and quick failure. When you pay a significant amount for a powerful LED of 1 or more watts, and after a couple of weeks it starts to shine noticeably worse, it’s really a pity for the money spent.
The fact is that the production of LED crystals is an expensive process that requires strict adherence to technology. In the process of assembling devices, the chips are tested and sorted. There are quite a few companies in the world involved in this process.
When buying an LED of dubious production, you run the risk of purchasing a 1 watt lighting device with a defective or simply low-quality chip. Therefore, it is recommended to buy only well-known brands of LEDs or contact a trusted supplier who tests the goods and is responsible for what they offer you.
To date, there are several large manufacturers involved in research and having their own developments. They definitely value their reputation:
Assembly in this case can be carried out in Malaysia, China, Taiwan, Europe and America. If you buy a genuine product (not a fake or imitation) of one of these brands, you can be sure of their quality.
The development of the industry has led to the fact that the characteristics of LEDs of 1 or more watts have almost leveled off. This allows customers not to be tied to a specific brand, but to choose LEDs based on their cost and ease of delivery.
Hello everyone, in this article I want to show you an overview of a 1 watt LED, and tell you where to get a suitable cooler, and how to securely attach an LED to it. Its exact brand is unknown, but this is not important - it is enough to know the parameters.Specification LED 1W
Read more in the datasheet. There is a wide range of colors available for sale. blue, white, red, yellow, green. In appearance they are the same. If we start the LED without a cooler, it will burn out in the first 5 seconds. We will use the cooler from the video card. The fan itself was supposed to be installed on a 10-watt matrix, but while it is on the way, we will do tests on a 1-watt LED.
I had such a cooler on my video card, which one you have - I don’t know, but I think it will work with any video cards - their power is more than that of the LED element. Next, on the reverse side, we glue double-sided tape (this is for if you need to remove the LED) and drip a drop of glue on top of it " Titanium" or " Moment". Securely fix the LED. Please note: if the LED is not glued tightly to the radiator, it may burn out!
Single Watt LED - video of work
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 various characteristics of LEDs, knowing which you can choose the right LED analogue. The use of LEDs, given their basic parameters, opens up an abundance of possibilities in the field of lighting.
The light-emitting diode (denoted by SD, SID, 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 spectrum range, and its color depends on the material of the semiconductor.
LEDs with red and yellow glow are made from inorganic semiconductor materials based on gallium arsenide, green and blue are made on the basis of indium gallium nitride. To increase the brightness of the light 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, as well as sources of decorative lighting. They are colored diodes placed in a translucent case, each of them has four leads. Devices emitting infrared light are used in devices for remote control of devices (remote control).
In the field of lighting, LEDs emitting white light are used. By color, LEDs are distinguished with cold white, neutral white and warm white glow. There is a classification of LEDs used for lighting according to the method of installation. The marking of the SMD LED means that the device consists of an aluminum or copper substrate on which a diode crystal is placed. The substrate itself is located in the 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 a phosphor are placed on one board. Thanks to this design, a high brightness of the glow is achieved. This technology is used in the production of high luminous flux in a relatively small area. In turn, this makes the production of LED lamps the most accessible and inexpensive.
Note! Comparing lamps on SMD and COB LEDs, it can be noted that the former can be repaired by replacing a failed LED. If the COB LED lamp does not work, you will have to change the entire board with diodes.
When choosing a suitable LED lamp for lighting, the parameters of the LEDs should be taken into account. These include supply voltage, power, operating current, efficiency (light output), glow temperature (color), radiation angle, dimensions, degradation period. Knowing the basic parameters, it will be possible to easily select devices to obtain one or another illumination result.
As a rule, for conventional LEDs, a current of 0.02A is provided. However, there are LEDs rated for 0.08A. These LEDs include more powerful devices, in the device of which four crystals are involved. They are located in the same building. Since each of the crystals consumes 0.02A, in total one device will consume 0.08A.
The stability of the operation of LED devices depends on the magnitude of the current. Even a slight increase in current helps to reduce the radiation intensity (aging) of the crystal and increase the color temperature. This eventually leads to the fact that the LEDs begin to cast blue and fail prematurely. And if the current strength indicator increases significantly, the LED immediately burns out.
To limit the current consumption, the designs of LED lamps and luminaires are provided with current stabilizers for LEDs (drivers). They convert the current, bringing it to the desired value for the LEDs. In the case when you want to connect a separate LED to the network, you need to use current-limiting resistors. The calculation of the resistance of the resistor for the LED is performed taking into account its specific characteristics.
Helpful advice! To choose the right resistor, you can use the calculator for calculating the resistor for the LED, posted on the Internet.
How to check 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 at the output of the LED when the rated current passes through it. The voltage value indicated on the packaging reflects just the voltage drop. Knowing this value, it is possible to 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 by the color of the glow of devices. For example, for blue, green and white crystals, the voltage is about 3V, for yellow and red - from 1.8 to 2.4V.
When using a parallel connection of LEDs of an identical rating with a voltage value of 2V, you may encounter the following: as a result of a scatter of parameters, some emitting diodes will fail (burn out), while others will glow very faintly. This will happen due to the fact that with an increase in voltage even by 0.1V, an increase in the current passing through the LED by 1.5 times is observed. Therefore, it is so important to ensure that the current matches the rating of the LED.
Comparison of the luminous flux of diodes with other light sources is carried out, taking into account the strength of the radiation emitted by them. Devices about 5 mm in diameter give from 1 to 5 lm of light. While the luminous flux of a 100W incandescent lamp is 1000 lm. But when comparing, it must be taken into account that a conventional lamp has diffused light, while an LED has a directional one. Therefore, it is necessary to take into account the scattering angle of the LEDs.
The scattering angle of different LEDs can be from 20 to 120 degrees. When illuminated, LEDs give a brighter light in the center and reduce illumination towards the edges of the dispersion angle. Thus, LEDs better illuminate a particular space while using less power. However, if it is required to increase the area of illumination, divergent lenses are used in the design of the lamp.
How to determine the power of LEDs? To determine the power of the LED lamp required to replace an incandescent lamp, it is necessary to apply a factor of 8. So, 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 of the table of correspondence between the power of incandescent lamps and LED light sources:
| Incandescent lamp power, W | Corresponding power of the 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, fluorescent - 35-40 lm / W, LED - 130-140 lm / W.
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 the glow temperature, among which warm white has a color temperature of less than 3300 K, daylight white - from 3300 to 5300 K and cold 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.
Color temperature is usually indicated on the label of LED lamps. It is indicated 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 shows the options for using LED sources with different glow temperatures:
| LED light color | Color temperature, K | Use cases in lighting | |
| White | Warm | 2700-3500 | Lighting of household and office premises as the most suitable analogue of an incandescent lamp |
| Neutral (daytime) | 3500-5300 | Excellent color rendering of such lamps allows them to be used for lighting workplaces in production. | |
| Cold | over 5300 | It is mainly used for street lighting, and is also used in the device of hand lamps. | |
| Red | 1800 | As a source of decorative and phyto-illumination | |
| Green | - | ||
| Yellow | 3300 | Lighting design of interiors | |
| Blue | 7500 | Illumination of surfaces in the interior, phyto-illumination | |
The wave nature of color makes it possible to express the color temperature of LEDs using wavelength. The marking of some LED devices reflects the color temperature precisely in the form of an interval of different wavelengths. Wavelength is denoted λ and is measured in nanometers (nm).
Given the size of SMD LEDs, fixtures are classified into groups with different specifications. The most popular LEDs are in sizes 3528, 5050, 5730, 2835, 3014 and 5630. Characteristics of SMD LEDs vary depending on the size. So, different types of SMD LEDs differ in brightness, color temperature, power. In the marking of the LEDs, the first two digits indicate the length and width of the device.
The main characteristics of SMD 2835 LEDs include an increased radiation area. Compared to the SMD 3528, which has a round work surface, the SMD 2835 emits a rectangular shape, which contributes to greater light output at a lower element height (about 0.8 mm). The luminous flux of such a device is 50 lm.
The body of SMD 2835 LEDs is made of heat-resistant polymer and can withstand temperatures up to 240°C. It should be noted that radiation degradation in these cells is less than 5% during 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.
According to the color of the glow, they distinguish warm white with a glow temperature of 4000 K, daylight white - 4800 K, pure white - from 5000 to 5800 K and cold white with a color temperature of 6500-7500 K. It should be noted that the maximum luminous flux for devices with cold white glow, the minimum - for warm white LEDs. In the design of the device, contact pads are increased, which contributes to better heat dissipation.
Helpful advice! SMD 2835 LEDs can be used for any type of mounting.
The design of the SMD 5050 housing contains three LEDs of the same type. Blue, red and green LED sources have technical characteristics similar to SMD 3528 crystals. The operating current value of each of the three LEDs is 0.02A, therefore the total current of the entire device is 0.06A. In order for the LEDs not to fail, it is recommended not to exceed this value.
SMD 5050 LED devices have a direct voltage of 3-3.3V and a light output (network flux) of 18-21 lm. The power of one LED is the sum of three power values of each crystal (0.7W) and is 0.21W. The color of the glow emitted by the devices can be white in all shades, green, blue, yellow and multi-color.
The close arrangement of LEDs of different colors in the same SMD 5050 package made it possible to implement multi-color LEDs with separate control of each color. Controllers are used to regulate lamps using SMD 5050 LEDs, 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.
SMD 5730 LEDs are modern representatives of LED devices, the body 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 high-efficiency luminous flux. In addition, they can work in conditions of high humidity, are resistant to temperature extremes and vibration, and have a long service life.
There are two types of devices: SMD 5730-0.5 with a power of 0.5W and SMD 5730-1 with a power of 1W. A distinctive feature of the devices is the possibility of their operation on a pulsed current. The value of the rated current of the SMD 5730-0.5 is 0.15A; during pulsed operation, the device can withstand currents up to 0.18A. This type of LED provides a luminous flux of up to 45 lm.
SMD 5730-1 LEDs operate at a constant current of 0.35A, with a pulsed mode - up to 0.8A. The light output efficiency of such a device can be up to 110 lm. Due to the heat-resistant polymer, the body of the device can withstand temperatures up to 250°C. The dispersion angle of both types of SMD 5730 is 120 degrees. The degree of degradation of the luminous flux is less than 1% when working for 3000 hours.
Cree (USA) is engaged in the development and production of super-bright and most powerful LEDs. One of the groups of Cree LEDs is represented by a series of Xlamp 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 glow angle using a minimum number of crystals.
In the XQ-E High Intensity series of LED sources, the glow angle is from 100 to 145 degrees. Having small geometric dimensions of 1.6x1.6 mm, the power of super-bright LEDs is 3 Volts, and the luminous flux is 330 lm. This is one of Cree's latest developments. All LEDs, the design of which is developed on the basis of a single chip, have high-quality color rendering within CRE 70-90.
Related article:
How to make or repair an LED garland yourself. Prices and main characteristics of the most popular models.
Cree has released several varieties of multi-chip LED fixtures with the latest power types from 6 to 72 volts. Multi-chip LEDs are divided into three groups, which include devices with high voltage, power up to 4W and above 4W. In sources up to 4W, 6 crystals are assembled in an MX and ML type package. The scattering angle is 120 degrees. You can buy Cree LEDs of this type with white warm and cold glow colors.
Helpful advice! Despite the high reliability and quality of light, you can buy high-power LEDs of the MX and ML series at a relatively low price.
The group above 4W includes LEDs from several crystals. The most dimensional devices in the group are 25W devices, represented by the MT-G series. The company's novelty is XHP model LEDs. One of the large LED-devices has a body of 7x7 mm, its power is 12W, the light output is 1710 lm. High voltage LEDs combine small size and high light output.
There are certain rules for connecting LEDs. Taking into account that the current passing through the device moves only in one direction, for a long and stable operation of LED devices, it is important to take into account not only a certain voltage, but also the optimal current value.
Depending on the power source used, there are two types of schemes for connecting LEDs to 220V. In one of the cases, it is used with a 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. The resistor in this circuit is not required, and the number of connected LEDs is limited by the power of the driver.
Two types of pictograms are used to designate LEDs in the diagram. Above each schematic representation of them are two small parallel arrows pointing upwards. They symbolize the bright glow of the LED device. Before you connect the LED to 220V using a power supply, you need to 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 will be stable in the circuit. Given the insignificant internal resistance of the LED device, turning it on without a current limiter will lead to the device burning. That is why an appropriate resistor is introduced into the LED switching circuit. It should be noted that resistors come in different ratings, so they should be calculated correctly.
Helpful advice! The negative point of the circuits for connecting an LED to a 220 Volt network using a resistor is the dissipation of high power when it is required to connect a load with increased current consumption. In this case, the resistor is replaced by a quenching capacitor.
When calculating the resistance for an LED, they are guided by the formula:
U = IхR,
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 strength. So that when you connect the 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, it is necessary 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 the resistor you need.
It often happens that, given the parameters of the LEDs, the resistance of the resistor has a non-standard value 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, the resistance of which has the nearest higher value compared to the calculated one. In this case, the LEDs will not function at full strength, but only by 90-97%, but this will be imperceptible to the eye and will positively affect the resource 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 setting the parameters of LED devices and current sources in the form field, you can find out the corresponding characteristics of the resistors. To determine the resistance of color-coded current limiters, there are also online resistor calculations for 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 a correct connection, it should be borne in mind that when the LEDs are connected in series, the required voltage is the sum of the voltage drops of each device. While when the LEDs are connected in parallel, the current strength is added.
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 two completely identical LEDs do not exist. Even devices of the same model have slight differences in parameters. This leads to the fact that when you connect a large number of them in a series or parallel circuit with a single resistor, they can quickly degrade and fail.
Note! When using one resistor in a parallel or series circuit, only LED devices with identical characteristics can be connected.
The discrepancy in the parameters when several LEDs are connected in parallel, let's say 4-5 pieces, will not affect the operation of the devices. And if you connect a lot of LEDs to such a circuit, it will be a bad decision. Even if the LED sources have a slight variation in characteristics, this will result in some fixtures emitting bright light and burning out quickly, while others will glow poorly. Therefore, when connecting in parallel, you should always use a separate resistor for each device.
With regard to series connection, there is an economical consumption, since the entire circuit consumes an amount of current equal to the consumption of one LED. With a parallel circuit, the consumption is the sum of the consumption of all LED sources included in the circuit included in the circuit.
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 are not always available commercially. 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 a direct voltage drop for typical LED devices is about 2V. The rated current for these LEDs corresponds to 0.02A. If you want 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 \u003d 500 (Ohm). Thus, a resistor with a nominal value of 510 ohms is needed, which is the closest in the series of electronic components E24.
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 the power is equal to the product of voltage and current, we calculate its value. We multiply the voltage of 10V by the current of 0.02A and get 0.2W. Thus, a resistor is needed, 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 borne in mind that the voltage falling on them will already be 4V. Accordingly, for the resistor it remains to pay off not 10V, but 8V. Therefore, 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: from the side of the anode, cathode, between the LEDs.
One way to check the working condition of the LEDs is to test with a multimeter. Such a device can diagnose LEDs of any design. Before checking the LED with a tester, the switch of the device is set in the "dialing" mode, and the probes are applied to the terminals. When the red probe is connected to the anode, and the black one to the cathode, the crystal should emit light. If the polarity is reversed, the display should show "1".
Helpful advice! Before testing the LED for functionality, it is recommended to dim the main lighting, as 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, in the holes located in the lower corner of the device, the anode is inserted into the hole with the symbol "E", and the cathode - with the pointer "C". If the LED is in working order, it should light up. This test method is suitable for LEDs with fairly long desoldered leads. The position of the switch with this method of verification does not matter.
How to check LEDs with a multimeter without soldering? To do this, solder pieces from a regular paper clip to the probes of the tester. As insulation, a textolite gasket is suitable, which is placed between the wires, after which it is processed with electrical tape. The output is a kind of adapter for connecting probes. The clips spring well and are securely fixed in the slots. In this form, you can connect the probes to the LEDs without soldering them out of the circuit.
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 analogues of industrial production. These can be color and music devices, flashing LED designs, do-it-yourself running lights on LEDs, and much more.
In order for the resource of the LED not to be exhausted ahead of schedule, it is necessary that the current flowing through it has a stable value. Red, yellow, and green LEDs are known to be able to handle higher current loads. While blue-green and white LED sources, even with a slight overload, burn out in 2 hours. Thus, for the normal operation of the LED, it is necessary to resolve the issue with its power supply.
If you assemble a chain of LEDs connected in series or in parallel, then you can provide them with identical radiation if the current passing through them has the same strength. In addition, reverse current pulses can adversely 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 features 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 chip. Elements for such an electronic circuit are of low cost and such a stabilizer is easy to construct.
When using a current stabilizer on the LM317 for LEDs, the current is regulated within 1A. The rectifier based on LM317L stabilizes the current up to 0.1A. Only one resistor is used in the device circuit. It is calculated using an online LED resistance calculator. Available handy devices are suitable for power: power supplies from a printer, laptop or other consumer electronics. It is not profitable to assemble more complex circuits on your own, since it is easier to purchase them ready-made.
The use of daytime running lights (DRL) on cars significantly increases the visibility of the car during daylight hours by other road users. Many motorists 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, consider the requirements of GOST: luminous flux 400-800 Cd, glow angle in the horizontal plane - 55 degrees, in the vertical - 25 degrees, area - 40 cm².
For the base, you can use an aluminum profile board with pads for mounting LEDs. The LEDs are fixed to the board with a heat-conductive adhesive. In accordance with the type of LED sources, optics are selected. In this case, lenses with an angle of illumination of 35 degrees are suitable. Lenses are installed on each LED separately. Wires are displayed in any convenient direction.
Next, a housing for DRL is made, which simultaneously serves as a radiator. To do this, you can use the U-shaped profile. The finished LED module is placed inside the profile, fixing it with screws. All free space can be filled with a transparent silicone-based sealant, leaving only the lenses on the surface. Such a coating will serve as a moisture protection.
The DRL is connected to the power supply with the obligatory use of a resistor, the resistance of which is pre-calculated and checked. Connection methods may vary depending on the vehicle model. Connection diagrams can be found on the Internet.
The most popular flashing LEDs, which you can buy ready-made, are devices that are regulated by the potential level. The flashing of the crystal occurs due to a change in the power supply at the terminals of the device. So, a two-color red-green LED device emits light depending on the direction of the current passing through it. The flashing effect in the RGB LED is achieved by connecting three outputs for separate control to a specific control system.
But you can also make a regular single-color LED blink, having a minimum of electronic components in your arsenal. Before you make a blinking LED, you need to choose a working circuit that is simple and reliable. You can use a blinking LED circuit, which will be powered by a 12V source.
The circuit consists of a low-power transistor Q1 (silicon high-frequency KTZ 315 or its analogues is suitable), a resistor R1 820-1000 Ohm, a 16-volt capacitor C1 with a capacity of 470 uF and an LED source. When the circuit is turned on, the capacitor charges up to 9-10V, after which the transistor opens for a moment and gives off the accumulated energy to the LED, which starts blinking. This scheme can be implemented only in the case of power supply from a 12V source.
You can assemble a more advanced circuit that works by analogy with a transistor multivibrator. The circuit includes KTZ 102 transistors (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 supply.
The circuit works on the principle of a "Darlington pair": capacitors C1 and C2 are alternately charged and discharged, which causes a particular transistor to open. When one transistor delivers power to C1, one LED lights up. Further, C2 is smoothly charged, and the base current of VT1 decreases, 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 rating to prevent failure of the LEDs.
To implement fairly complex color music schemes on LEDs with your own hands, you must first understand how the simplest color music scheme works. It consists of one transistor, resistor and LED device. Such a circuit can be powered from a source with a rating of 6 to 12V. The operation of the circuit occurs due to cascade amplification with a common emitter (emitter).
The base VT1 receives a signal with varying amplitude and frequency. In the event that the signal fluctuations exceed the specified threshold, the transistor opens and the LED lights up. The disadvantage of this scheme is the dependence of flashing on the degree of the sound signal. Thus, the effect of color music will appear only at a certain degree of sound volume. If the sound is increased. the LED will be on all the time, and when it decreases, it will flash a little.
To achieve a full-fledged effect, they use a color music scheme on LEDs with a breakdown of the sound range into three parts. The circuit with a three-channel sound converter is powered by 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 tape, an RGB LED tape, as well as schemes for smoothly turning LEDs on and off. Also on the network you can find schemes of running lights on LEDs.
The voltage indicator circuit includes a resistor R1 (variable resistance 10 kOhm), resistors R1, R2 (1 kOhm), two transistors VT1 KT315B, VT2 KT361B, three LEDs - HL1, HL2 (red), HLZ (green). X1, X2 - 6-volt power supplies. In this circuit, it is recommended to use LED-devices with a voltage of 1.5V.
The operation algorithm of a self-made 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. Increasing the voltage causes the red LED located on the right to glow. With the resistor in the middle position, all transistors will be in the closed position, and only the central green LED will receive voltage.
The opening of the transistor VT1 occurs when the slider of the resistor is moved up, thereby increasing the voltage. In this case, the supply of voltage to HL3 stops, and it is applied to HL1. When you move the slider down (lowering the voltage), the transistor VT1 closes and VT2 opens, which will power the HL2 LED. 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 obsolete 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.
