DIY driver for LEDs powered by 220 V. LED lamp circuit: simple driver design

The widespread use of LEDs has led to the mass production of power supplies for them. Such blocks are called drivers. Their main feature is that they are able to stably maintain a given current at the output. In other words, a driver for light emitting diodes (LEDs) is a source of current to power them.

Purpose

Since LEDs are semiconductor elements, the key characteristic that determines the brightness of their glow is not voltage, but current. In order for them to be guaranteed to work for the stated number of hours, a driver is needed - it stabilizes the current flowing through the LED circuit. It is possible to use low-power light-emitting diodes without a driver; in this case, its role is played by a resistor.

Application

Drivers are used both when powering the LED from a 220V network, and from DC voltage sources of 9-36 V. The former are used when lighting rooms with LED lamps and strips, the latter are more often found in cars, bicycle headlights, portable lanterns, etc.

Principle of operation

As already mentioned, the driver is a current source. Its differences from a voltage source are illustrated below.

The voltage source produces a certain voltage at its output, ideally independent of the load.

For example, if you connect a 40 Ohm resistor to a 12 V source, a current of 300 mA will flow through it.

If you connect two resistors in parallel, the total current will be 600 mA at the same voltage.

The driver maintains the specified current at its output. The voltage may change in this case.

Let's also connect a 40 Ohm resistor to the 300 mA driver.

The driver will create a 12V voltage drop across the resistor.

If you connect two resistors in parallel, the current will still be 300 mA, but the voltage will drop to 6 V:

Thus, an ideal driver is capable of delivering the rated current to the load regardless of voltage drop. That is, an LED with a voltage drop of 2 V and a current of 300 mA will burn as brightly as an LED with a voltage of 3 V and a current of 300 mA.

Main characteristics

When selecting, you need to take into account three main parameters: output voltage, current and power consumed by the load.

The driver output voltage depends on several factors:

• LED voltage drop;
• number of LEDs;
• connection method.

The driver output current is determined by the characteristics of the LEDs and depends on the following parameters:

• LED power;
• brightness.

The power of LEDs affects the current they consume, which can vary depending on the required brightness. The driver must provide them with this current.

Load power depends on:

• power of each LED;
• their quantities;
• colors.

In general, power consumption can be calculated as

where Pled is the LED power,

N is the number of connected LEDs.

The maximum driver power should not be less.

It is worth considering that for stable operation of the driver and to prevent its failure, a power reserve of at least 20-30% should be provided. That is, the following relationship must be satisfied:

where Pmax is the maximum driver power.

In addition to the power and number of LEDs, the load power also depends on their color. LEDs of different colors have different voltage drops for the same current. For example, the red XP-E LED has a voltage drop of 1.9-2.4 V at 350 mA. Its average power consumption is thus about 750 mW.

The green XP-E has a drop of 3.3-3.9 V at the same current, and its average power will be about 1.25 W. That is, a driver rated at 10 watts can power either 12-13 red LEDs or 7-8 green ones.

How to choose a driver for LEDs. LED connection methods

Let's say there are 6 LEDs with a voltage drop of 2 V and a current of 300 mA. You can connect them in various ways, and in each case you will need a driver with certain parameters:

It is unacceptable to connect 3 or more LEDs in parallel in this way, since too much current may flow through them, as a result of which they will quickly fail.

Please note that in all cases the driver power is 3.6 W and does not depend on the method of connecting the load.

Thus, it is more advisable to select a driver for LEDs already at the stage of purchasing the latter, having previously determined the connection diagram. If you first purchase the LEDs themselves, and then select a driver for them, this may not be an easy task, since the likelihood that you will find exactly the power source that can ensure the operation of exactly this number of LEDs connected according to a specific circuit is small.

Kinds

In general, LED drivers can be divided into two categories: linear and switching.

The linear output is a current generator. It provides stabilization of the output current with an unstable input voltage; Moreover, the adjustment occurs smoothly, without creating high-frequency electromagnetic interference. They are simple and cheap, but their low efficiency (less than 80%) limits their scope of application to low-power LEDs and strips.

Pulse devices are devices that create a series of high-frequency current pulses at the output.

They usually operate on the principle of pulse width modulation (PWM), that is, the average value of the output current is determined by the ratio of the pulse width to their repetition period (this value is called the duty cycle).

The diagram above shows the operating principle of a PWM driver: the pulse frequency remains constant, but the duty cycle varies from 10% to 80%. This leads to a change in the average value of the output current I cp.

Such drivers are widely used due to their compactness and high efficiency (about 95%). The main disadvantage is the higher level of electromagnetic interference compared to linear ones.

220V LED driver

For inclusion in a 220 V network, both linear and pulsed ones are produced. There are drivers with and without galvanic isolation from the network. The main advantages of the former are high efficiency, reliability and safety.

Without galvanic isolation are usually cheaper, but less reliable and require care when connecting, as there is a risk of electric shock.

Chinese drivers

The demand for drivers for LEDs contributes to their mass production in China. These devices are pulsed current sources, usually 350-700 mA, often without a housing.

Chinese driver for 3w LED

Their main advantages are low price and the presence of galvanic isolation. The disadvantages are the following:

• low reliability due to the use of cheap circuit solutions;
• lack of protection against overheating and fluctuations in the network;
• high level of radio interference;
• high level of output ripple;
• fragility.

Life time

Typically, the service life of the driver is shorter than that of the optical part - manufacturers provide a guarantee of 30,000 hours of operation. This is due to factors such as:

• instability of mains voltage;
• temperature changes;
• humidity level;
• driver load.

The weakest link of the LED driver is the smoothing capacitors, which tend to evaporate the electrolyte, especially in conditions of high humidity and unstable supply voltage. As a result, the level of ripple at the driver output increases, which negatively affects the operation of the LEDs.

Also, the service life is affected by incomplete driver load. That is, if it is designed for 150 W, but operates at a load of 70 W, half of its power returns to the network, causing it to overload. This causes frequent power failures. We recommend reading about.

Driver circuits (chips) for LEDs

Many manufacturers produce specialized driver chips. Let's look at some of them.

ON Semiconductor UC3845 is a pulse driver with an output current of up to 1A. The driver circuit for a 10w LED on this chip is shown below.

Supertex HV9910 is a very common pulse driver chip. The output current does not exceed 10 mA and has no galvanic isolation.

A simple current driver on this chip is shown below.

Texas Instruments UCC28810. Network pulse driver has the ability to organize galvanic isolation. Output current up to 750 mA.

Another microcircuit from this company, a driver for powering powerful LM3404HV LEDs, is described in this video:

The device operates on the principle of a Buck Converter type resonant converter, that is, the function of maintaining the required current here is partially assigned to a resonant circuit in the form of coil L1 and Schottky diode D1 (a typical circuit is shown below). It is also possible to set the switching frequency by selecting a resistor R ON.

Maxim MAX16800 is a linear microcircuit that operates at low voltages, so you can build a 12 volt driver on it. The output current is up to 350 mA, so it can be used as a power driver for a powerful LED, flashlight, etc. There is a possibility of dimming. A typical diagram and structure is presented below.

Conclusion

LEDs are much more demanding on the power supply than other light sources. For example, exceeding the current by 20% for a fluorescent lamp will not entail a serious deterioration in performance, but for LEDs the service life will be reduced several times. Therefore, you should choose a driver for LEDs especially carefully.

Today, LED lamps are found in almost every home. But unfortunately, these lighting devices often fail long before their expected time, and there are many reasons for this. Throwing away? Not worth it, it can be repaired. Today we will disassemble several of these devices down to the screws, see what is inside them, and try to repair a 220 V LED lamp with our own hands.

LED lamp device

Before we undertake practical repairs, let’s understand the operation of a 220 V LED lamp theoretically.

Any LED light bulb (SL) is a ready-made LED lamp, which consists of a set of LEDs placed on a specific board equipped with a radiator to remove heat from the diodes. Often the metal body of the lamp plays the role of a radiator.

Diodes connected in series feed the driver - a current source. In budget devices, the current through the LEDs is not stabilized and directly depends on fluctuations in the mains voltage. In more expensive lamps, the current through semiconductors is stabilized at a given level. The second option, of course, is much more reliable than the first, but such a lamp costs a little more and is more difficult to repair.

This entire device is placed in a housing of one design or another, which is equipped with a base for connecting to a 220 V network and a protective cap, which simultaneously plays the role of a light diffuser.

Design of a 220 V LED lamp

On the lamp shown above, the role of a heat sink is played by a part of the body made of ribbed metal. In some lamp designs, the housing may be plastic, and the radiator is located inside it.

In these light bulbs, the radiator is located inside a plastic housing equipped with ventilation holes

Driver circuits and their operating principles

To carry out a successful repair, you must have a clear understanding of how the lamp works. One of the main components of any LED lamp is the driver. There are many driver circuits for 220 V LED lamps, but they can be divided into 3 types:

1. With current stabilization.
2. With voltage stabilization.
3. No stabilization.

Only devices of the first type are, in essence, drivers. They limit the current through the LEDs. The second type is better called a power supply for LED strip. It’s difficult to name the third one at all, but its repair, as I indicated above, is the simplest. Let's look at the circuits of lamps on drivers of each type.

Driver with current stabilization

The lamp driver, the diagram of which you see below, is assembled on an integrated current stabilizer SM2082D. Despite its apparent simplicity, it is complete and of high quality, and its repair is simple.

LED-A60 lamp circuit on a full driver

The mains voltage is supplied through fuse F to the diode bridge VD1-VD4, and then, already rectified, to the smoothing capacitor C1. The constant voltage thus obtained is supplied to the LEDs of the lamp HL1-HL14, connected in series, and pin 2 of the DA1 chip.

From the very first output of this microcircuit, the LEDs receive a current-stabilized voltage. The amount of current depends on the value of resistor R2. Resistor R1 is quite large, a shunt capacitor, and does not participate in the operation of the circuit. It is needed to quickly discharge the capacitor when you unscrew the light bulb. Otherwise, if you grab the base, you risk getting a serious electric shock, since C1 will remain charged to a voltage of 300 V.

Driver with voltage regulation

This circuit, in principle, is also quite high quality, but you need to connect it to the LEDs a little differently. As I said above, such a driver would be more correctly called a power supply, since it stabilizes not the current, but the voltage.

Power supply circuit for an LED lamp

Here, the mains voltage is first supplied to the ballast capacitor C1, which reduces it to approximately 20 V, and then to the diode bridge VD1-VD4. Next, the rectified voltage is smoothed by capacitor C2 and supplied to an integrated voltage stabilizer. It is smoothed again (C3) and, through the current-limiting resistor R2, powers a chain of LEDs connected in series. Thus, even if the mains voltage fluctuates, the current through the LEDs will remain constant.

The difference between this circuit and the previous one is precisely this current-limiting resistor. Essentially, this is with a ballast power supply.

Driver without stabilization

The driver assembled according to this circuit is a miracle of Chinese circuit design. However, if the voltage in the network is normal and does not fluctuate much, it works. The device is assembled according to the simplest circuit and does not stabilize either current or voltage. It simply lowers it (voltage) to approximately the desired value and straightens it.

The simplest driver for a 220 V LED lamp

In this diagram you see the already familiar damping (ballast) capacitor, shunted by a resistor for safety. Next, the voltage is supplied to the rectifier bridge, smoothed out by a capacitor of an offensively small capacity - only 10 μF - and through a current-limiting resistor it is supplied to the LED chain.

What can be said about such a “driver”? Since it does not stabilize anything, the voltage on the LEDs and, accordingly, the current through them directly depend on the input voltage. If it is too high, the lamp will burn out quickly. If it “jumps”, the light will also blink.

This solution is usually used in budget lamps from Chinese manufacturers. It is, of course, difficult to call it successful, but it occurs quite often and can work for quite a long time at normal network voltage. In addition, such circuits are easy to repair.

Reasons for failure

Why do LED lamps burn out at all if, as LED manufacturers claim, the lifespan of light-emitting semiconductors is at least 15-20 thousand hours? Almost all drivers do not have mechanical elements and contacts, which means their MTBF should be no less. But the lamps burn, sometimes without even expiring their warranty period, and this is a fact. There can be several reasons for a light bulb to break:

• Manufacturing defect. Alas, no one is immune from this. Especially if the manufacturers of components and LEDs are our Chinese brothers, working in the garage and on their knees.
• Incorrect operation. For example, poor ventilation in a closed lamp. In such light sources, the lamp overheats, and then anything can fail - from the driver to the LEDs. This also includes dust, moisture, a “sparking” switch, a backlit switch, etc.

Expert opinion

Alexey Bartosh

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If your switch has a backlight, then this is a sure way to the rapid death of the LED lamp. Either remove the backlight, or screw an ordinary incandescent light bulb of any, even the lowest power, into one of the chandelier arms.

This backlighting of the switch is convenient, but it causes the LED lamp to “wink” and reduces its service life by tens of times.

• Poor nutrition. If the voltage constantly fluctuates or is abnormally high, then even the best-quality driver can “lose patience.” This also includes constant voltage surges, for example, when starting powerful motors or welding equipment, and impulse noise.

In this Chinese lamp, the “driver” is located right on the board with LEDs, and there’s not even a smell of a radiator here

Example of LED light bulb repair

If the lamp does fail, do not throw it away immediately. Firstly, it is likely that it can be revived by making repairs yourself. Secondly, even if the repair is not successful, the surviving parts may be useful for repairing another lamp.

You should only undertake repairs to a light bulb if you are sure that it is the light bulb that is faulty, and not the socket, socket or wiring. This is easy to check: just replace the lamp with a known good one and make sure that it lights up.

What do we need for repairs?

Before you undertake any repairs, you need to collect everything you need for this. To work you will need:

• low power soldering iron;
• tweezers;
• sharp knife;
• solvent (if necessary);

Any multimeter will do - dial or digital, the main thing is that it must have a diode continuity mode.

This device is suitable: it has a diode test mode

How to disassemble an LED lamp

Here you need to immediately make a reservation: if your filament lamp has failed, then you should not undertake repairs. The device has a sealed glass flask filled with an inert gas. It is simply impossible to repair such a device.

This lamp cannot be repaired.

So, if everything is ready, and your lamp is not filament, then you can start repairing the LED lamp. First of all, the light bulb must be disassembled. To do this, you need to remove the light-diffusing cap. This is usually easy to do. There are three ways to attach the diffuser to the device body:

1. Using a threaded connection.
2. Using latches.
3. Using sealant.

It is easiest to disassemble a lamp with a threaded connection. To do this, simply unscrew the glass from the case without applying too much force.

The diffuser of this lamp can simply be unscrewed

Disassembling a lamp with latches is not much more difficult. The only thing is to determine the location of the latches, since they are not visually visible. Carefully insert the tip of the knife between the diffuser and the body and at the same time try to remove the cap. With some patience and carefully moving the knife around the circle, you will easily find the latches.

Disassembling a lamp with a snap-on cap

If the diffuser is placed on a sealant, then you will have to tinker with the repair a little longer. Scratch the joint between the cap and the body with a thin (preferably a stationery) knife. Do this at an angle towards the base and as deep as possible, but without fanaticism. Now try to unscrew the cap as if it were threaded. If the sealant is of poor quality or there is not enough of it, the light-diffusing cap can be easily removed.

Disassembling an LED light bulb on sealant using a utility knife

Did not work out? There are two more repair options. Take a syringe and pour paint solvent (not acetone!) into the gap formed. After some time, the sealant will become soft and the cap can be easily removed.

The second repair method is to heat the joint with a technical hair dryer. This must be done very carefully so as not to melt the plastic of the lamp body, and the glass of the diffuser does not burst. The heated sealant will become soft and the diffuser can be easily removed.

Expert opinion

Alexey Bartosh

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

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Important. When disassembling the light bulb, be patient and be careful: the body of the device and the cap are easy to break. In this case, you will most likely have to forget about repairs.

The result of careless disassembly, when there is no point in repairing

All that remains is to unscrew the fastening screws holding the board with LEDs, remove it and pull out the driver. Disassembly can be considered completed, it’s time to move on to repairs.

Unscrew the two screws holding the board with LEDs

If there are no screws, then most likely the board is secured with sealant. Cut it along the circumference of the board, and carefully pry the board itself with a knife.

This board is secured to the case with sealant

Troubleshooting

The lamp has been disassembled and all its components can be reached. Great. Start the repair with a visual inspection of all driver parts. All elements must have a “healthy” appearance: not darkened, not swollen or burnt.

In the left picture the electrolytic smoothing capacitor has failed, in the right picture the quenching capacitor has failed

Carefully inspect the soldering areas: they must be of high quality, without cracks or holes in the solder.

The problem with this lamp is cold soldering - the element has poor contact with the board

If visually everything is in order with the driver, inspect the board with LEDs. Usually (but not always) a burnt-out LED is visible: it either burns out or burns out completely.

On the left, the burnt crystal burned through the phosphor, on the right, the diode burned out completely

Since all light-emitting diodes are connected in series, if only one LED burns out, the others will also stop lighting.

It is quite clear that if problems are found, they need to be eliminated: burnt parts should be replaced with similar ones, and suspicious soldering should be soldered with a well-heated soldering iron with a large amount of flux. You can read how to replace the LED in the next section of the article. Found the above problems and fixed them? Turn on the lamp and hopefully the repair is complete.

If everything is visually in order, it’s time to use a tester for further repairs. First, let's deal with the board with LEDs, since they are easier to check, and the probability of failure of this node is higher. We turn on the multimeter to check the diodes and ring each LED in both directions. In one direction the device will show a high resistance, in the other the diode will light up faintly.

A working diode in one of the positions of the multimeter probes will light up

Can't ring a single diode? Perhaps the driver is interfering with this. Unsolder one of the wires going from the driver to the LED board and repeat the test.

If the driver interferes with diode testing, you can disable it by unsoldering one of the power wires from the module

If one of the diodes behaves differently from the others, it must be replaced with one of the same type. If everything is in order, you can finish checking the LED module - it is working. It's time to move on to driver repair.

Driver repair

First of all, check the fuse, if there is one. The device should show zero resistance. This can be done without removing the fuse from the board. Did the device show infinitely high resistance? Replace the fuse and plug in the lamp to test. Is it glowing? The renovation is complete. If the fuse is OK, we continue the repair. . You can find out in detail how to do this.

Is the diode bridge working? Then unsolder the smoothing electrolytic capacitor and ring it. If the capacitor is working properly, then at the initial moment of continuity the multimeter will show a small resistance, which will grow before our eyes until it goes to infinity.

Checking an electrolytic capacitor with a multimeter

If the driver is simple, as often happens, then all these manipulations will certainly lead to success and completion of the repair. If the driver is more complex, then all you can do is ring the remaining electrolytic capacitors and diodes. It is easier to completely unsolder capacitors; only one terminal of a diode can be unsoldered. To make it lose contact with the board, it is enough to lift the device with a needle or tweezers.

If everything is in order here, then, alas, for further more complex repairs you will have to use the help of a qualified electronics engineer.

Replacing LEDs

The main disadvantage of SMD elements is the occurrence of some problems with the repair of equipment containing them. Dismantling such elements, especially multi-pin ones, can be very problematic. But if the device is two-terminal, then you can desolder it using a soldering station, and then the repair is greatly simplified. Take the double soldering iron that comes with the soldering station, heat both leads of the diode at the same time and with the same soldering iron, like tweezers, remove the element from the board.

Removing an SMD capacitor using a double soldering iron

If your soldering station only has one soldering iron (which is most often the case), then there is another option. You can use the hair dryer included with the soldering station. Blow the faulty diode with a hairdryer and at the same time try to move it from its place with a needle or thin tweezers. Once the solder has melted, the LED can be easily removed from the board.

Removing the LED with a hairdryer

To repair LED lamps, you can use a technical one instead of a soldering gun, but the diameter of its nozzle should be minimal. Otherwise, you will heat the aluminum substrate and either you will not solder anything at all (the power of the hair dryer is not enough), or all the LEDs of the lamp will fall out of their places, or the conductive paths will fall off. In this case, repairs will be seriously complicated, if possible at all.

How to replace LEDs in a lamp if you don’t have a hair dryer or soldering station

Of course, not everyone has a soldering station for such repairs (I, for example, don’t have one at home). In this case, you can use a regular soldering iron for repairs, slightly modifying its tip. Just wind a copper winding wire with a diameter of 1-2 mm onto the tip, and sharpen and tin the ends of the wire. Why not a soldering station for repairing and replacing SMD parts?

Removing an SMD LED using a regular soldering iron

All that remains is to replace the LED, and the repair can be completed. This can be done with a soldering iron with a thin tip or a regular one, but modified for desoldering (see photo above). Before soldering, remove excess solder from the contact pads and apply flux to them. Now place the new LED in place, observing the polarity, hold it with thin tweezers and solder. Keep in mind that the soldered LED must be exactly the same type as the burnt one. Otherwise, such repairs will not last long.

Safety precautions when repairing 220 V LED light bulbs

Since we are repairing a device that operates from the network, there is no need for safety precautions. LED lamps have transformerless power supply; almost all elements of the circuit during operation of the device, including LEDs, are under life-threatening voltage. Therefore, observe the following precautions:

• All soldering and measurements during repairs should be carried out only with the lamp turned off.
• Even if the capacitors are bypassed with discharge resistors, after turning off the lamp, discharge all capacitors manually. To do this, just short-circuit the capacitor leads for a second with any metal tool with a dielectric handle.
• When turning on the device after repair, take care of your eyes. If something goes wrong, any of the elements can explode. Better turn away, turn on and turn around.
• Do not leave a switched-on soldering iron unattended and do not place it on flammable objects during repair breaks. 260 degrees is relatively little, but enough to start a fire.

We can probably end here. Now you know how an LED lamp works and how it works. And if necessary, you can repair it yourself.

Video

The advantages of LED paws have been discussed many times. The abundance of positive reviews from users of LED lighting willy-nilly makes you think about Ilyich’s own light bulbs. Everything would be nice, but when it comes to calculating the conversion of an apartment to LED lighting, the numbers are a little “straining”.

To replace an ordinary 75W lamp, you need a 15W LED bulb, and a dozen such lamps need to be replaced. With an average cost of about $10 per lamp, the budget comes out to be decent, and the risk of purchasing a Chinese “clone” with a life cycle of 2-3 years cannot be ruled out. In light of this, many are considering the possibility of making these devices themselves.

Power theory for LED lamps from 220V

The most budget option can be assembled with your own hands from these LEDs. A dozen of these little ones cost less than a dollar, and the brightness corresponds to a 75W incandescent lamp. Putting everything together is not a problem, but if you don’t connect them directly to the network, they will burn out. The heart of any LED lamp is the power driver. It determines how long and how well the light bulb will shine.

To assemble a 220-volt LED lamp with your own hands, let’s look at the power driver circuit.

The network parameters significantly exceed the needs of the LED. In order for the LED to operate from the network, it is necessary to reduce the voltage amplitude, current strength and convert the alternating voltage of the network into direct voltage.

For these purposes, a voltage divider with a resistor or capacitive load and stabilizers are used.

Components of a LED luminaire

A 220-volt LED lamp circuit will require a minimum number of available components.

• LEDs 3.3V 1W – 12 pcs.;
• ceramic capacitor 0.27 µF 400-500V – 1 pc.;
• resistor 500 kOhm - 1 Mohm 0.5 - 1 W - 1 pcs.t;
• 100V diode – 4 pcs.;
• electrolytic capacitors 330 μF and 100 μF 16V 1 pc.;
• 12V voltage stabilizer L7812 or similar – 1 pc.

Making a 220V LED driver with your own hands

The 220 volt ice driver circuit is nothing more than a switching power supply.

As a homemade LED driver from a 220V network, we will consider the simplest switching power supply without galvanic isolation. The main advantage of such schemes is simplicity and reliability. But be careful when assembling, since this circuit has no current limit. The LEDs will draw their required one and a half amperes, but if you touch the bare wires with your hand, the current will reach tens of amperes, and such a shock of current is very noticeable.

The simplest driver circuit for 220V LEDs consists of three main stages:

• Capacitive voltage divider;
• diode bridge;
• voltage stabilization cascade.

First cascade– capacitive reactance on capacitor C1 with resistor. The resistor is necessary for self-discharge of the capacitor and does not affect the operation of the circuit itself. Its rating is not particularly critical and can be from 100 kOhm to 1 Mohm with a power of 0.5-1 W. The capacitor is necessarily non-electrolytic at 400-500V (effective peak voltage of the network).

When a half-wave of voltage passes through a capacitor, it passes current until the plates are charged. The smaller its capacity, the faster the full charge occurs. With a capacity of 0.3-0.4 μF, the charging time is 1/10 of the half-wave period of the mains voltage. In simple terms, only a tenth of the incoming voltage will pass through the capacitor.

Second cascade- diode bridge. It converts alternating voltage to direct voltage. After cutting off most of the half-wave voltage with a capacitor, we get about 20-24V DC at the output of the diode bridge.

Third cascade– smoothing stabilizing filter.

A capacitor with a diode bridge acts as a voltage divider. When the voltage in the network changes, the amplitude at the output of the diode bridge will also change.

To smooth out the voltage ripple, we connect an electrolytic capacitor in parallel to the circuit. Its capacity depends on the power of our load.

In the driver circuit, the supply voltage for the LEDs should not exceed 12V. The common element L7812 can be used as a stabilizer.

The assembled circuit of a 220-volt LED lamp begins to work immediately, but before connecting it to the network, carefully insulate all exposed wires and soldering points of circuit elements.

Driver option without current stabilizer

There are a huge number of driver circuits on the network for LEDs from a 220V network that do not have current stabilizers.

The problem with any transformerless driver is the ripple of the output voltage, and therefore the brightness of the LEDs. A capacitor installed after the diode bridge partially copes with this problem, but does not completely solve it.

There will be ripple on the diodes with an amplitude of 2-3V. When we install a 12V stabilizer in the circuit, even taking into account ripple, the amplitude of the incoming voltage will be higher than the cutoff range.

Voltage diagram in a circuit without a stabilizer

Diagram in a circuit with a stabilizer

Therefore, a driver for diode lamps, even one assembled with one’s own hands, will not be inferior in pulsation level to similar units of expensive factory-made lamps.

As you can see, assembling the driver with your own hands is not particularly difficult. By changing the parameters of the circuit elements, we can vary the output signal values ​​within wide limits.

If you want to build a 220-volt LED floodlight circuit based on such a circuit, it is better to convert the output stage to 24V with an appropriate stabilizer, since the output current of the L7812 is 1.2A, this limits the load power to 10W. For more powerful lighting sources, it is necessary to either increase the number of output stages, or use a more powerful stabilizer with an output current of up to 5A and install it on a radiator.

Powerful LEDs in lighting devices are connected through electronic drivers that stabilize the current at their output.

Nowadays, so-called energy-saving fluorescent lamps (compact fluorescent lamps - CFLs) have become widespread. But over time, they fail. One of the causes of the malfunction is burnout of the lamp filament. Do not rush to dispose of such lamps because the electronic board contains many components that can be used in the future in other home-made devices. These are chokes, transistors, diodes, capacitors. Typically, these lamps have a functional electronic board, which makes it possible to use them as a power supply or driver for an LED. As a result, in this way we will get a free driver for connecting LEDs, which is even more interesting.

You can watch the process of making homemade products in the video:

List of tools and materials
-energy saving fluorescent lamp;
-screwdriver;
- soldering iron;
-tester;
-white LED 10W;
-enamel wire with a diameter of 0.4 mm;
-thermal paste;
- diodes of the HER, FR, UF brand for 1-2A
-desk lamp.

Step one. Disassembling the lamp.
We disassemble the energy-saving fluorescent lamp by carefully prying it off with a screwdriver. The lamp bulb cannot be broken as there is mercury vapor inside. We call the filament of the bulb with a tester. If at least one thread shows a break, then the bulb is faulty. If there is a working similar lamp, then you can connect the bulb from it to the electronic board being converted to make sure that it is working properly.

Step two. Remaking the electronic converter.
For the modification, I used a 20W lamp, the choke of which can withstand a load of up to 20 W. For a 10W LED this is enough. If you need to connect a more powerful load, you can use an electronic lamp converter board with the appropriate power, or change the inductor with a larger core.

It is also possible to power LEDs of lower power by selecting the required voltage by the number of turns on the inductor.
I mounted wire jumpers on the pins to connect the lamp filaments.

20 turns of enamel wire need to be wound over the primary winding of the inductor. Then we solder the secondary wound winding to the rectifier diode bridge. We connect 220V voltage to the lamp and measure the voltage at the output from the rectifier. It was 9.7V. An LED connected through an ammeter consumes a current of 0.83A. This LED has a rated current of 900mA, but in order to increase its service life, the current consumption is specially reduced. The diode bridge can be assembled on the board by surface mounting.

Diagram of the converted electronic converter board. As a result, from the inductor we get a transformer with a connected rectifier. Added components are shown in green.

Step three. Assembling an LED table lamp.
We remove the 220 volt lamp socket. I installed a 10W LED using thermal paste on a metal lampshade of an old table lamp. The table lamp shade serves as a heat sink for the LED.

The electronic power board and diode bridge were placed in the housing of the table lamp stand.

After an hour of work, I measured the heating temperature of the LED and it showed 40 degrees Celsius.

According to my feelings, the illumination from the LED is approximately equivalent to a 100-watt incandescent lamp.

Despite the high cost, the energy consumption of semiconductor lamps (LED) is much less than that of incandescent lamps, and their service life is 5 times longer. The LED lamp circuit operates with a supply of 220 volts, when the input signal causing the glow is converted to an operating value using a driver.

LED lamps 220 V

Whatever the supply voltage, a constant voltage of 1.8-4 V is supplied to one LED.

Types of LEDs

An LED is a semiconductor crystal made of several layers that converts electricity into visible light. When its composition changes, radiation of a certain color is obtained. The LED is made on the basis of a chip - a crystal with a platform for connecting power conductors.

To produce white light, the “blue” chip is coated with a yellow phosphor. When the crystal emits radiation, the phosphor emits its own. Mixing yellow and blue light creates white.

Different chip assembly methods allow you to create 4 main types of LEDs:

1. DIP - consists of a crystal with a lens located on top and two conductors attached. It is the most common and is used for lighting, lighting decorations and displays.
2. “Piranha” is a similar design, but with four terminals, which makes it more reliable for installation and improves heat dissipation. Mostly used in the automotive industry.
3. SMD LED - placed on the surface, due to which it is possible to reduce dimensions, improve heat dissipation and provide many design options. Can be used in any light sources.
4. COB technology, where the chip is soldered into the board. Due to this, the contact is better protected from oxidation and overheating, and the glow intensity is significantly increased. If an LED burns out, it must be completely replaced, since DIY repairs by replacing individual chips are not possible.

The disadvantage of the LED is its small size. To create a large, colorful light image, many sources are required, combined into groups. In addition, the crystal ages over time, and the brightness of the lamps gradually decreases. For high-quality models, the wear process is very slow.

LED lamp device

The lamp contains:

• frame;
• base;
• diffuser;
• radiator;
• LED block;
• transformerless driver.

220 volt LED lamp device

The figure shows a modern LED lamp using SOV technology. The LED is made as one unit, with many crystals. It does not require wiring of numerous contacts. It is enough to connect just one pair. When a lamp with a burnt-out LED is repaired, the entire lamp is replaced.

The shape of the lamps is round, cylindrical and others. Connection to the power supply is made through threaded or pin sockets.

For general lighting, lamps with 2700K, 3500K and 5000K are selected. The spectrum gradations can be any. They are often used for advertising lighting and for decorative purposes.

The simplest driver circuit for powering a lamp from the mains is shown in the figure below. The number of parts here is minimal, due to the presence of one or two quenching resistors R1, R2 and the back-to-back connection of LEDs HL1, HL2. This way they protect each other from reverse voltage. In this case, the flickering frequency of the lamp increases to 100 Hz.

The simplest diagram for connecting an LED lamp to a 220 volt network

The supply voltage of 220 volts is supplied through the limiting capacitor C1 to the rectifier bridge, and then to the lamp. One of the LEDs can be replaced with a regular rectifier, but the flickering will change to 25 Hz, which will have a bad effect on vision.

The figure below shows a classic LED lamp power supply circuit. It is used in many models and can be removed for DIY repairs.

Classic scheme for connecting an LED lamp to a 220 V network

The electrolytic capacitor smooths out the rectified voltage, which eliminates flicker at a frequency of 100 Hz. Resistor R1 discharges the capacitor when the power is turned off.

with your own hands

A simple LED lamp with individual LEDs can be repaired by replacing faulty elements. It can be easily disassembled if you carefully separate the base from the glass body. There are LEDs inside. The MR 16 lamp has 27 of them. To access the printed circuit board on which they are located, you need to remove the protective glass by prying it off with a screwdriver. Sometimes this operation is quite difficult to do.

LED lamp 220 volts

Burnt-out LEDs are immediately replaced. The rest should be ringed with a tester or a voltage of 1.5 V should be applied to each. The serviceable ones should light up, and the rest must be replaced.

The manufacturer calculates the lamps so that the operating current of the LEDs is as high as possible. This significantly reduces their service life, but it is not profitable to sell “eternal” devices. Therefore, a limiting resistor can be connected in series to the LEDs.

If the lights blink, the cause may be a failure of capacitor C1. It should be replaced with another one with a rated voltage of 400 V.

LED lamps are rarely made again. It is easier to make a lamp from a faulty one. In fact, it turns out that repair and production of a new product is one process. To do this, the LED lamp is disassembled and the burnt-out LEDs and driver radio components are restored. There are often original lamps on sale with non-standard lamps, which are difficult to find replacements in the future. A simple driver can be taken from a faulty lamp, and LEDs from an old flashlight.

The driver circuit is assembled according to the classic model discussed above. Only resistor R3 is added to it to discharge capacitor C2 when turned off and a pair of zener diodes VD2, VD3 to bypass it in case of an open circuit of the LEDs. You can get by with one zener diode if you choose the right stabilization voltage. If you select a capacitor for voltages greater than 220 V, you can do without additional parts. But in this case, its dimensions will increase and after the repair is done, the board with the parts may not fit into the base.

LED lamp driver

The driver circuit is shown for a lamp of 20 LEDs. If their number is different, it is necessary to select a capacitance value for capacitor C1 such that a current of 20 mA passes through them.

The power supply circuit for an LED lamp is most often transformerless, and care should be taken when installing it yourself on a metal lamp so that there is no phase or zero short circuit to the housing.

Capacitors are selected according to the table, depending on the number of LEDs. They can be mounted on an aluminum plate in the amount of 20-30 pieces. To do this, holes are drilled in it, and LEDs are installed on hot-melt adhesive. They are soldered sequentially. All parts can be placed on a printed circuit board made of fiberglass. They are located on the side where there are no printed tracks, with the exception of LEDs. The latter are attached by soldering the pins on the board. Their length is about 5 mm. The device is then assembled in the luminaire.

LED table lamp

220 V lamp. Video

You can learn about making a 220 V LED lamp with your own hands from this video.

A properly made homemade LED lamp circuit will allow you to operate it for many years. It may be possible to repair it. Power sources can be any: from a regular battery to a 220-volt network.