LED hl1 technical specifications. Application of LEDs in electronic circuits. How to test an LED with a multimeter

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

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

Before you start repairing an LED lamp, you need to understand its structure. Regardless of the appearance and type of LEDs used, all LED lamps, including filament bulbs, are designed the same. If you remove the walls of the lamp housing, you can see the driver inside, which is a printed circuit board with radio elements installed on it.

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

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

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

About filament lamps

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

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

Examples of LED lamp repairs

Attention, the electrical circuits of the LED lamp drivers are galvanically connected to the phase of the electrical network and therefore extreme care should be taken. Touching an unprotected part of a person’s body to exposed parts of a circuit connected to an electrical network can cause serious damage to health, including cardiac arrest.

LED lamp repair
ASD LED-A60, 11 W on SM2082 chip

Currently, powerful LED light bulbs have appeared, the drivers of which are assembled on SM2082 type chips. One of them worked for less than a year and ended up being repaired. The light went out randomly and came on again. When you tapped it, it responded with light or extinguishing. It became obvious that the problem was poor contact.

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

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

An external inspection did not reveal any defective soldering or broken tracks. I had to remove the board with LEDs. To do this, the silicone was first cut off and the board was pryed off by the edge with a screwdriver blade.

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

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

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

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

Since the soldering did not raise any suspicions, I first checked the reliability of the contact in the central terminal of the base. It can be easily removed if you pry it over the edge with a knife blade. But the contact was reliable. Just in case, I tinned the wire with solder.

It is difficult to remove the screw part of the base, so I decided to use a soldering iron to solder the soldering wires coming from the base. When I touched one of the soldering joints, the wire became exposed. A “cold” solder was detected. Since there was no way to get to the wire to strip it, I had to lubricate it with FIM active flux and then solder it again.

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

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

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

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

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

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

LED lamp repair
ASD LED-A60, 11 W, 220 V, E27

The repair included another ASD LED-A60 LED lamp, similar in appearance and with the same technical characteristics as the one repaired above.

When turned on, the lamp came on for a moment and then did not shine. This behavior of LED lamps is usually associated with a driver failure. So I immediately started disassembling the lamp.

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

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

It was also not possible to remove the board together with the aluminum insert, since it fit tightly to the case and was seated with the outer surface on silicone.

I decided to try removing the driver board from the base side. To do this, first, a knife was pryed out of the base and the central contact was removed. To remove the threaded part of the base, it was necessary to slightly bend its upper flange so that the core points would disengage from the base.

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

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

As it turned out, the board had an extension whose shoulders rested against the lamp body. It looks like the board was shaped this way to limit movement, although it would have been enough to fix it with a drop of silicone. Then the driver would be removed from either side of the lamp.

The 220 V voltage from the lamp base is supplied through a resistor - fuse FU to the MB6F rectifier bridge and is then smoothed out by an electrolytic capacitor. Next, the voltage is supplied to the SIC9553 chip, which stabilizes the current. Parallel connected resistors R20 and R80 between pins 1 and 8 MS set the amount of LED supply current.

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

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

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

In the end, all my efforts to remove the driver turned out to be useful only for understanding the LED lamp structure. The driver turned out to be OK.

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

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

A multimeter or tester turned on in resistance measurement mode produces a voltage within 3-4 V. I had to check the LEDs using a power supply, supplying 12 V to each LED through a 1 kOhm current-limiting resistor.

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

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

Just for fun, I did some measurements and calculations. The current flowing through the LEDs was 58 mA, the voltage was 8 V. Therefore, the power supplied to one LED was 0.46 W. With 16 LEDs, the result is 7.36 W, instead of the declared 11 W. Perhaps the manufacturer has indicated the total power consumption of the lamp, taking into account losses in the driver.

The service life of the ASD LED-A60, 11 W, 220 V, E27 LED lamp declared by the manufacturer raises serious doubts in my mind. In the small volume of the plastic lamp body, with low thermal conductivity, significant power is released - 11 W. As a result, the LEDs and driver operate at the maximum permissible temperature, which leads to accelerated degradation of their crystals and, as a consequence, to a sharp reduction in their time between failures.

LED lamp repair
LED smd B35 827 ERA, 7 W on BP2831A chip

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

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

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

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

A typical driver circuit on the BP2831A chip taken from the datasheet is shown in the photograph. The driver board was removed and all simple radio elements were checked; they all turned out to be in good order. I had to start checking the LEDs.

The LEDs in the lamp were installed of an unknown type with two crystals in the housing and inspection did not reveal any defects. By connecting the leads of each LED in series, I quickly identified the faulty one and replaced it with a drop of solder, as in the photo.

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

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

Why is it permissible to short-circuit the terminals of burnt-out LEDs in LED lamps?

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

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

For example, if 50 LEDs are connected in series to the driver, and each of them drops a voltage of 3 V, then the voltage at the driver output is 150 V, and if you short-circuit 5 of them, the voltage will drop to 135 V, and the current will not change.

But the efficiency of the driver assembled according to this scheme will be low and the power loss will be more than 50%. For example, for an LED light bulb MR-16-2835-F27 you will need a 6.1 kOhm resistor with a power of 4 watts. It turns out that the resistor driver will consume power that exceeds the power consumption of LEDs and placing it in a small LED lamp housing will be unacceptable due to the release of more heat.

But if there is no other way to repair an LED lamp and it is very necessary, then the resistor driver can be placed in a separate housing; anyway, the power consumption of such an LED lamp will be four times less than incandescent lamps. It should be noted that the more LEDs connected in series in a light bulb, the higher the efficiency will be. With 80 series-connected SMD3528 LEDs, you will need an 800 Ohm resistor with a power of only 0.5 W. The capacitance of capacitor C1 will need to be increased to 4.7 µF.

Finding faulty LEDs

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

When inspecting the appearance of the LEDs, you need to carefully examine the quality of the soldering of their terminals. One of the light bulbs being repaired turned out to have four LEDs that were poorly soldered.

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

Faulty LEDs may not have any changes in appearance. Therefore, it is necessary to check each LED with a multimeter or pointer tester turned on in resistance measurement mode.

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

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

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

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

If suddenly all the LEDs light up, it means that the shorted one is definitely faulty. This method is suitable if only one LED in the circuit is faulty. With this method of checking, it is necessary to take into account that if the driver does not provide galvanic isolation from the electrical network, as for example in the diagrams above, then touching the LED solders with your hand is unsafe.

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

Other malfunctions of LED lamps

If checking the LEDs showed their serviceability, then the reason for the light bulb’s inoperability lies in the driver or in the soldering areas of the current-carrying conductors.

For example, in this light bulb a cold solder connection was found on the conductor supplying power to the printed circuit board. The soot released due to poor soldering even settled on the conductive paths of the printed circuit board. The soot was easily removed by wiping with a rag soaked in alcohol. The wire was soldered, stripped, tinned and re-soldered into the board. I was lucky with the repair of this light bulb.

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

Soldering SMD LEDs

To replace a faulty LED, it must be desoldered without damaging the printed conductors. The LED from the donor board also needs to be desoldered for replacement without damage.

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

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

If the LED burns out like carbon, and the printed circuit board underneath is charred, then before installing a new LED, you must clean this area of ​​the printed circuit board from burning, since it is a current conductor. When cleaning, you may find that the LED solder pads are burnt or peeled off.

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

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

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

The design of LED SMD lamps of this type is very convenient for repair, since there is access to test the LEDs and replace them without disassembling the lamp body. True, I still disassembled the light bulb for fun in order to study its structure.

Checking the LEDs of an LED corn lamp is no different from the technology described above, but we must take into account that the SMD5050 LED housing contains three LEDs at once, usually connected in parallel (three dark points of the crystals are visible on the yellow circle), and during testing all three should glow.

A faulty LED can be replaced with a new one or short-circuited with a jumper. This will not affect the reliability of the lamp, only the luminous flux will decrease slightly, unnoticeably to the eye.

The driver of this lamp is assembled according to the simplest circuit, without an isolating transformer, so touching the LED terminals when the lamp is on is unacceptable. Lamps of this design must not be installed in lamps that can be reached by children.

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

To do this, you need to remove the rim from the side opposite the base. Using a small screwdriver or a knife blade, try in a circle to find the weak spot where the rim is glued the worst. If the rim gives way, then using the tool as a lever, the rim will easily come off around the entire perimeter.

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

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

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

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

The lamp base was made of aluminum, cored around the circumference and held tightly. I had to drill out the mounting points with a 1.5 mm drill. After this, the base, pryed off with a knife, was easily removed.

But you can do without drilling the base if you use the edge of a knife to pry it around the circumference and slightly bend its upper edge. You should first put a mark on the base and body so that the base can be conveniently installed in place. To securely fasten the base after repairing the lamp, it will be enough to put it on the lamp body in such a way that the punched points on the base fall into the old places. Next, press these points with a sharp object.

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

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

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

In the electrical circuit of the driver of this lamp, protection elements are already installed, C1 for protection against pulse surges and R2, R3 for protection against current surges. When checking the elements, resistors R2 were immediately found to be open on both drivers. It appears that the LED lamp was supplied with a voltage that exceeded the permissible voltage. After replacing the resistors, I didn’t have a 10 ohm one at hand, so I set it to 5.1 ohms, and the lamp started working.

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

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

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

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

Checking the LEDs with a tester showed that they are working properly, therefore, the driver is faulty and we need to get to it. The aluminum board was secured with four screws, which I unscrewed.

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

Due to the fact that the plastic part to which the radiator was attached was held very tightly, I decided to go the proven route, remove the base and remove the driver through the opened hole for repair. I drilled out the core points, but the base was not removed. It turned out that it was still attached to the plastic due to the threaded connection.

I had to separate the plastic adapter from the radiator. It held up just like the protective glass. To do this, a cut was made with a hacksaw for metal at the junction of the plastic with the radiator and by turning a screwdriver with a wide blade, the parts were separated from each other.

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

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

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

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

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

Three nine super-bright crystal LEDs are installed on an aluminum printed circuit board. The board is screwed to the heatsink with three screws. Checking the LEDs showed their serviceability. Therefore, the driver needs to be repaired. Having experience in repairing a similar LED lamp "LLB" LR-EW5N-5, I did not unscrew the screws, but unsoldered the current-carrying wires coming from the driver and continued disassembling the lamp from the base side.

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

The screws that fasten the plastic ring of the base are covered by the driver, and it is difficult to see them, but they are on the same axis with the thread to which the transition part of the radiator is screwed. Therefore, you can reach them with a thin Phillips screwdriver.

The driver turned out to be assembled according to a transformer circuit. Checking all elements except the microcircuit did not reveal any failures. Consequently, the microcircuit is faulty; I couldn’t even find a mention of its type on the Internet. The LED light bulb could not be repaired; it will be useful for spare parts. But I studied its structure.

Repair of LED lamp series "LL" GU10-3W

At first glance, it turned out to be impossible to disassemble a burnt-out GU10-3W LED light bulb with protective glass. An attempt to remove the glass resulted in its chipping. When great force was applied, the glass cracked.

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

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

In order to disassemble this LED light bulb, I had to drill a hole with a diameter of 2.5 mm in its aluminum case at the level of the surface of the printed circuit board. The drilling location must be chosen in such a way that the drill does not damage the LED when exiting. If you don’t have a drill at hand, you can make a hole with a thick awl.

Next, a small screwdriver is inserted into the hole and, acting like a lever, the glass is lifted. I removed the glass from two light bulbs without any problems. If checking the LEDs with a tester shows their serviceability, then the printed circuit board is removed.

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

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

In order to prevent accidental contact of the resistor terminal, to which the mains voltage is connected, with the metal body of the lamp, it was insulated with a drop of hot-melt adhesive. It is waterproof and an excellent insulator. I often use it to seal, insulate and secure electrical wires and other parts.

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

After replacing the resistors, the functionality of both bulbs was restored. All that remains is to secure the printed circuit board and protective glass in the lamp body.

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

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

When gluing the printed circuit board, in order not to wait, holding the board in place, since the wires were pushing it out, I additionally fixed the board at several points using hot glue.

The LED lamp began to flash like a strobe light

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

One instance of the LED lamp began to blink immediately after being turned on for the first few seconds and then the lamp began to shine normally. Over time, the duration of the lamp's blinking after switching on began to increase, and the lamp began to blink continuously. The second instance of the LED lamp suddenly began blinking continuously.

After disassembling the lamps, it turned out that the electrolytic capacitors installed immediately after the rectifier bridges in the drivers had failed. It was easy to determine the malfunction, since the capacitor housings were swollen. But even if the capacitor looks free of external defects in appearance, then the repair of an LED light bulb with a stroboscopic effect must still begin with its replacement.

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

Online calculators for determining resistor values
by color marking

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

LEDs or LIGHT EMITTING DIODES (in the English version LED - Light Emitting Diode) are well known to every electronics engineer. These are semiconductor devices that convert electric current into light radiation. Their main advantages: high efficiency, close to monochrome radiation, miniature size, mechanical strength, high reliability, low heat generation, up to 10 years of operating time without turning off the power. Finally, LEDs are low-voltage devices, and therefore extremely electrically safe.

The first industrial samples of red LEDs appeared in 1962 (General Electric Corp.). In 1976, orange, green and yellow LEDs were developed, and in 1993 the first blue semiconductor emitters appeared (Nichia Corporation). In amateur designs, “red” and “green” LEDs are most often used, less often “blue” and “white”.

Typical efficiency values ​​for standard LEDs range from 1 to 10%. For comparison, the efficiency of a steam engine is 5...7%. For powerful modern LEDs this figure reaches 12...35%.

In Table. Table 2.1 shows the parameters of low-power LEDs with a luminous intensity of no more than 1000 MKd. Their feature is a significant technological spread in the current-voltage characteristic (volt-ampere characteristic). As a consequence, for a particular LED, the forward current / PR and forward voltage V np are known only approximately. When calculating this, people usually turn a blind eye, since in most cases the LED is required to state the fact “on” or “off”.

Table 2.1. Parameters of low-power LEDs for general use

Conditional stresses 1.6; 1.7; 1.8; 3.5 V characterize the starting point of the rise in the current-voltage characteristic curve, respectively, for the “red”, “yellow”, “green” and “blue”/“white” indicators. It is these numbers that will be indicated in the future in electrical diagrams near the designation of LEDs. However, the actual operating voltage V pr is approximately 0.1…0.4 V greater than the initial one, which depends on the flowing current (Fig. 2.1).

Rice. 2.1. Typical current-voltage characteristics of low-power LEDs from Kingbright.

Important notes.

1. Do not set the constant forward current / PR through the LED close to the maximum limit specified in the datasheet. Typically this is 20 mA. Long-term operation with this current reduces long-term reliability. To obtain acceptable brightness, it is enough to set the current to 4...10 mA.

2. LEDs allow a pulsed operating mode, in which the forward current / PR can be increased 3...6 times to 60...120 mA while maintaining the average current for a period of no more than 20...25 mA. When making calculations, we must not forget that as the current increases, the voltage also increases. For example, for a “green” LED at a current of 15 mA, the voltage V PR = 2.1 V, and at a current of 75 mA V np = 2.7 V.

3. The red color of the indication does not guarantee that the LED belongs to the group with the conditional beginning of the I-V curve of 1.6 V (although in most cases this is exactly the case). A “red” LED may have a “green” I-V characteristic with a rise point of 1.8 V. It all depends on the chemical composition from which the emitter is made, and this parameter is a priori unknown when purchased on the radio market. The situation is similar with powerful “green” LEDs, which can have a “blue” I-V characteristic with a rise point of 3.5 V.

4. Some datasheets for LEDs indicate the maximum permissible reverse voltage U OBR = 2...5 V. But this is just a test voltage at which the reverse leakage current, equal to several tens of microamps, is checked at the manufacturer.

5. The LED fails not from high reverse voltage, but from exceeding the power dissipated on it. Studies have shown that green and red LEDs have a “zener diode” current-voltage characteristic with a fairly steep bend. At a reverse voltage of 12...35 V, a reversible breakdown of the n-p junction occurs. If the breakdown current does not exceed 2...4 mA, then the dissipation power remains within the limits regulated by the datasheet of 75...150 mW.

Practical conclusion - if the MK supply voltage is within 3..5 V, there is no fear of “confusing” the polarity when soldering the “red-orange-yellow-green” indicators. All of them are guaranteed to remain intact.

“Blue” and “white” LEDs are much more gentle in this regard. They are afraid of electrostatic potentials that can accumulate on clothing and on the human body. The reverse voltage for them should not exceed 5 V and they should be treated approximately the same way as field-effect transistors.

In Fig. 2.2, a...g shows diagrams for connecting single LEDs to one MK line. In Fig. 2.3, a...M shows diagrams for connecting single LEDs to several MK lines.

Rice. 2.2. Schemes for connecting single LEDs to one MK line (beginning):

a) standard current limiting circuit through the HL1 LED using resistor R1. For reference, the idealized MK has G 1H = 4.75 V at a load current of 5...10 mA and G 1H = 4.5 V at a load current of 20 mA;

b) similar to Fig. 2.2, a, but with inversion of the signal at the MK output For reference, the idealized MK has V OL = 0.15...0.3 V at load current

5.. . 10 mA and V OL = 0.4…0.5 V at a load current of 20 mA. If the MK outputs have a symmetrical load capacity, then between the circuits in Fig. 2.2, a and in Fig. 2.2, b no difference;

c) direct connection of the HL1 LED to the MK line is possible, but only with a low supply voltage. Operating point K PR = 2 V at / PR = 15 mA. However, in each specific case, you need to check the load capacity graphs of MK lines according to the datasheet;

d) connecting LED HL1 to an increased voltage source of +9 V through a quenching zener diode VD1. Check calculation - the sum of the supply voltage MK (5 V) and the stabilization voltage VD1 (5.6 V) must be greater than the difference between the increased voltage (9 V) and the voltage drop on the HL1 LED (1.7...1.9 V); ABOUT

About Fig. 2.2. Schemes for connecting single LEDs to one MK line (end):

e) LED HL1 has a built-in integral resistor that limits forward current. In the datasheet, instead of the resistor resistance, the permissible operating voltage of the LED is indicated at a current of no more than 20 mA. Classification number when ordering: 3; 5; 12 V;

e) it is assumed that the HL1 LED is located at a considerable distance from MK and is connected to contact pads XI, X? long wires. Resistors R1, R2 - current protection, in case of wire breakage and short circuit to the metal body of the device, which, as a rule, is connected to the GND circuit (“ground”);

g) the effect of smooth extinguishing of the HL1 LED. In the initial state, the MK output level is LOW, the LED is off. A HIGH level at the MK output quickly turns on the LED, and then smoothly decreases its brightness as capacitor C1 charges. Diode VD1 helps discharge capacitor C/ at a LOW level at the MK output.

Rice. 2.3. Schemes for connecting single LEDs to several MK lines (beginning):

a) LEDs HL1...HLn are switched on independently of each other at a HIGH level at the MK output. Resistors R1…Rn limit the currents through the LEDs and determine the brightness of their glow. The total current through the +5 V power supply pin at a HIGH level on all outputs should not exceed 100...300 mA (look in the datasheet for a specific MK);

b) similar to Fig. 2.3, a, but with an active LOW level and with a separate power supply for the LEDs. If the MK outputs have a symmetrical load capacity and the LED power supply is +5 V, then the circuits in Fig. 2.3, a and in Fig. 2.3, b are equivalent;

c) a typical technique for reducing the number of resistors. It is used if the simultaneous lighting of several indicators is not required, otherwise their brightness will decrease due to the increased voltage across the resistor R1\O

d) similar to Fig. 2.3, in, but with a “running zero” at the MK outputs;

e) the HL1 indicator lights up when the upper MK line is set to HIGH and the lower line is LOW, while other nodes can be connected to the MK outputs;

e) MK generates 8 gradations of brightness of the HL1 LED. Resistors R1…R3 determine the dynamic range and degree of linearity of the characteristic;

g) the ultra-bright HL1 LED requires increased current, which is achieved by paralleling the MK lines. At each of them, the levels must be set synchronously;

h) similar to Fig. 2.3, g, but with synchronous HIGH levels at the MK outputs;

i) LED HL1 indicates the presence of “running unit” pulses at three MK outputs; j) automatic continuation of a long cable. On MK lines, it is programmatically generated

“running unit” (on one line there is a HIGH level, on the others there is a LOW level). If any wire breaks, the LED in this circuit will be constantly extinguished; ABOUT

About Fig. 2.3. Schemes for connecting single LEDs to several MK lines (end):

l) in the initial state, all MK outputs have HIGH levels, the HL1, HL2, HL4 indicators are lit. In the event of an accident, the LOW level is set at one or more MK outputs, the corresponding indicator goes out, and HL3\m automatically starts to light) with a large number of LEDs, it makes sense to unload the MK power terminals by directing the incoming and outgoing currents to different circuits. In particular, LEDs HL1...HL8 reduce the load on the +5 V pin of MK, and LEDs HL9...HL16 reduce the load on the GND pin of MK.

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:

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:

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.

Related article:

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 value. 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.