12 volt power supply for tape. How to choose and calculate the power supply for the LED strip. Differences between a power supply and a driver

Using LED lighting in the interior, it is important that its operation is stable, durable and does not have a harmful effect on human vision. The correct functioning of LED devices is provided by voltage converters, which should be selected by making some calculations. A properly selected power supply for a 12V LED strip will protect the LEDs from voltage drops and premature loss of glow quality.

Unlike conventional incandescent lamps, LED designs cannot be connected to a 220V network. They are available with a supply voltage of 12V or 24V. As a backlight in home interiors, 12V LED strips are most in demand. To obtain the required voltage, special adapters are used - power sources that convert the voltage in the 220V network to the required value of 12V.

Before choosing a power supply for an LED strip, you should familiarize yourself with their types and characteristics. Stabilizers for LED products differ according to the following criteria:

• degree of protection - there are models hermetic and non-hermetic;
• body design - plastic, aluminum sealed for rooms with a high level of humidity, metal with perforation and contact pads (used for dry rooms and requires installation in a closed place to prevent dust).

Voltage stabilizers are an essential element of high quality lighting, ensuring maximum efficiency of LED light sources. They supply the necessary parameters with electricity, protecting against possible power surges and premature failure. Thanks to power supplies, LED strips emit a uniform glow without flickering.

Power supply for LED strip 12V: calculation and connection of the device

To understand which power supply is needed for the LED strip, it is necessary to make certain calculations that take into account not only the output voltage, but also the amount of current supplied to the load. Therefore, for each specific backlight, you should calculate the total value of the current consumed by all the LEDs in the tape.

Options for calculating the power supply for the LED strip

Before calculating the power supply for the LED strip, you need to read the accompanying documentation for the product, which indicates the current consumption of one running meter. In the absence of such data, the calculation can be made independently.

For example, let's calculate the total number of LEDs for a 12V strip 15 m long, with a density of 30 SMD 5050 LEDs per meter: 15 (m) x 30 (pcs) = 450 pcs. Considering that each SMD 5050 LED consumes a current of 0.02A (this value is given in the diode parameters table), the total current consumption of the entire strip is 9A (450x0.02 = 9). Therefore, a 12V power supply with a current carrying capacity of 9A will be required.

Helpful advice! Overall power supplies are quite difficult to hide in the cornice design. Therefore, to illuminate ceilings, it is not recommended to use tapes with a high density of LEDs, which require powerful converters.

When calculating the power of the power supply for the LED strip, we multiply the voltage and the resulting current value: 12Vx9A = 108 W. Therefore, a stabilizer with a power of at least 108W will be acceptable. However, it should be noted that the unit is selected with a 20% power reserve, otherwise it will quickly fail from overload. This means that the required power will be: 108x1.2 \u003d 129.6 W, i.e. for this case, the choice of a power supply for a 12V LED strip - 150 W will be optimal.

In addition, you can calculate the converter power using data on the main characteristics of flexible LED products. Having selected the desired type of tape, we find in the table the corresponding power value of one meter and multiply by the total length of the backlight. Considering the power reserve, we get the required power of the power supply.

Table of main technical indicators LED strips 12V:

LED class	LED size, mm²	LED strip power, W/m	Tape density, pcs/m	Luminous flux value, lm/m
SMD 3528	3.5x2.8	2,4	30	150
		4,8	60	300
		9.6	120	600
SMD 5050	5x5	7,2	30	360
		14,4	60	720

An example of connecting an LED strip to a power supply

It is necessary to mount the backlight to the selected surface after the power supply is connected to the LED strip. For example, we use the connection of a tape to a block, the body of which is made of metal and has holes for cooling the constituent elements and the terminal strip. One of the walls of the housing is equipped with a plate indicating the marking for the correct connection of wires.

Terminals with the designation "L" and "N" - phase and zero, are intended for connection to a 220V network. Grounding is marked with the symbols "FG". The terminals marked "G" are interconnected and are designed to connect the negative output of the LED strip. The three terminals with the symbols "V" are also connected inside the adapter and the positive terminal is connected to them respectively. It should be noted that this marking is also used on other converter models.

To connect a single-color tape, we connect the wires to the terminals, taking into account the polarity. The mains plug has three sheathed wires in brown, blue and green/yellow. We attach the brown and blue wires to the “phase” and “zero” terminals, not being afraid to mix them up, since they can be interchanged. The yellow-green wire is connected strictly to the ground terminal. If there is no ground, the terminal is not used: it does not matter for the functioning of the tape.

Note! The absence of a ground wire in the power cord is a violation of safety regulations when performing electrical work.

The above example of connecting an LED strip to a power supply is suitable for using a backlight from a single strip up to 5 m long. If you need to connect several pieces of tape, then you need to use a parallel connection scheme.

Scheme of parallel connection of LED strip power supplies

If during interior design it becomes necessary to highlight several decorative elements located at a certain distance from each other, parallel connection of tape segments to a voltage converter is used. Such a scheme is also used in the case when the lighting line of the structure is long enough and exceeds 5 m.

Serial connection of segments will lead to an uneven distribution of the load, as a result of which the LED strip will not work correctly, emitting weak light in the final section. It is possible that the extreme section of the tape will not glow at all, while the initial one will start to overheat and quickly fail. This suggests that it is impossible to connect the end of the first segment to the beginning of the second.

At parallel connection, each segment of the LED strip must be connected to a power source independently of the others. This can be done by connecting each piece of tape to the power supply with separate wires. But a parallel connection can be made in another way: lay the main line of wire from the converter, to which you can later connect individual sections of the LED strip.

In order for the contact of the tape conductors with the main wire to be reliable and strong, they use soldering or connection through special connectors - connectors. The use of connectors for connecting connectors greatly simplifies the repair of the backlight in the event that a malfunction occurs during operation. If the tape needs to be laid along a complex path, the tape itself can be used as the main wire.

The price of the power supply for LED strip 12V

You can buy a power supply for a 12V LED strip not only at lighting sales points, but also on the web pages of manufacturers and organizations selling LED products. There you can get acquainted with the range of converter models, their technical characteristics and the cost of blocks.

By contacting site managers, you can get professional advice on how to choose a power supply for an LED strip, depending on its type and operating conditions. Experienced specialists will help in choosing the right device that will ensure long-term and high-quality operation of the LED design. As a rule, all products are certified and provided with a guarantee from the manufacturer.

Note! When purchasing an open type transducer, remember that it can only be used in rooms with a minimum degree of humidity and in places where there is no risk of water ingress.

Before you buy a power supply for an LED strip, it is worth reviewing the cost of products offered by different companies. This will help in choosing a model with the necessary parameters on favorable terms. Estimated prices for power supplies for 12V LED strip are presented in the table:

Inverter model	Dimensions, mm	Main settings	price, rub.
PSU interior 12V 15W IP 20	70/39/30	Supply voltage 110-220V, power 15W, equipped with power indicator and voltage regulator	270
PSU 12V 35W IP 20	85/58/32	Supply voltage 110-220V, power 35W, has a power indicator and voltage regulator	380
PSU 12V 60W IP 20	159/98/38	Supply voltage 110-220V, power 60W, has a power indicator and voltage regulator	540
PSU 12V 150W IP 20	200/89/40	Supply voltage 110-220V, power 150W, equipped with power indicator and voltage regulator	780
PSU waterproof 12V 30W IP 67	220/28/20	Supply voltage 110-220V, power 30W, protection against moisture and dust	560
PSU waterproof 12V 60W IP 67	148/40/30	Supply voltage 110-220V, power 60W, protection against moisture and dust	1100
PSU waterproof 12V 100W IP 67	202/71,2/45	Supply voltage 110-220V, power 100W, protection against moisture and dust	1670

Sometimes there are situations when it is necessary to make a backlight on a small area. Then the purchase of a power supply will cost much more than buying the tape itself. In this case, you can make the converter yourself.

How to make a do-it-yourself power supply for an LED strip

The cost of switching power supplies for a high power LED strip often exceeds the flexible strip itself. However, there is an option to reduce the cost of a backlight device by using power supplies from outdated models of computers, TVs, tablets or other electrical appliances as a stabilizer. Surely such products can be found in every home.

The power of 12V converters from old electronics is usually from 6 to 36W. This is quite enough for the functioning of a small segment LED backlight, for example, kitchen apron zones. You can use transformer models, but they are quite heavy and their power exceeds the same tape parameter twice. As a result, when such a power supply is connected to the tape, it overheats greatly, even if it is improved by means of an additional cooling device.

For normal operation of the LED strip, it is better to use switching power supplies, which, with sufficient power, weigh very little. Suitable, for example, a converter for 12V and 2A from a failed TV. The power of such a device is 24W (12x2), which allows the LED strip to work properly, and the power supply does not overheat.

Helpful advice! Chargers from 5V mobile phones can be used as a power source for a small self-assembled night lamp of 3-6 LEDs.

You can adapt the electronic ballast (current limiter), which fed the fluorescent lamp that failed, under the power supply for the 12V tape. To do this, it is necessary to convert the fluorescent lamp regulator into a step-down transformer, after which, using the circuit, connect an LED strip to it. The transformation is a winding of the secondary winding, then a secondary diode and a capacitor are added to the circuit. The main condition is that the power of the tape must correspond to the same ballast parameter.

Performing repairs to the power supply for LED strips

12V voltage sources that have failed are usually repairable. If you have enough knowledge and skills, you can try to repair the voltage converter yourself. Faults can be eliminated using the power supply circuit for the 12V or 24V LED strip, as they are identical.

The most common power supply problems are:

• capacitors C22, C23 fail - usually they swell or dry out;
• transistors T10-11 do not function;
• the PWM controller TL494 is faulty;
• dual diode D33, capacitors C30-33.

Malfunctions of other components of the converters are rare, but they are also worth checking.

To diagnose and fix problems, follow these steps:

• open the case and check the fuse. If everything is in order with it, it is necessary to measure the voltage on the capacitors (C22, C23), having previously applied power. The value should be around 310V. Therefore, the surge protector and rectifier are normal;
• carry out PWM diagnostics (KA7500 microcircuit) - if there is a voltage of 12-30V on pin 12, then we check the microcircuit. Otherwise, check the standby voltage power supply;
• the voltage at pin 14 after applying external power should be approximately + 5V. If not, you need to replace the chip. If there is, you need to check the microcircuit with an oscilloscope.

Repair of the power supply consists in replacing faulty elements with the same components or their analogues. In order not to encounter a breakdown problem later, it is necessary to follow the manufacturer's recommendations, since exceeding the permissible load limit will lead to the failure of the adapter.

Right choice power supply and related devices for LED systems guarantees the durability and quality of lighting. Thanks to these devices, LED sources emit a bright, flicker-free light that can elegantly transform your interior.

The wide variety of modern lighting technology impresses even people with a very rich imagination. With cosmic speed, new, more and more technological developments appear, providing not only high-quality and safe lighting, but also maximum energy savings.

One of such progressive directions is LED technology. Currently, the market offers a wide selection of LED strips, lamps and fixtures that differ in design and technical characteristics. These devices have become an excellent alternative to the usual incandescent lamps and energy-saving lighting fixtures.

LED backlighting is widely used today in advertising and production areas, in interior design, in the design of car interiors, equipment household appliances etc. A huge range of proposed options for LED lighting allows you to easily choose required option, but its connection to the network raises a lot of questions for many.

The main component of the LED system is the power supply, which is a miniature transformer that provides power to the LEDs. Small dimensions allow you to discreetly place this device in any convenient places without violating the aesthetics of the LED design.

Purpose of the power supply

When using LED strips in interior design, it is necessary to take into account some features of such a solution.

First of all, you should know that directly connect the led strip to the socket like an ordinary light bulb, it will not work. This is due to the fact that the operating voltage of the tape is far from 220 V. If you plug it into a regular outlet, it will simply fail.

So, if an ordinary incandescent lamp runs on 220 V, then the LEDs require only 12 V (this is the most common option, but there are also 24-volt models). Therefore, in order to connect a 12-volt lighting device to a standard household network, it is required to lower the voltage to the required value. Can cope with this task power supply for LED strip 12V.

Types of power supplies for LED strips

1. 1. Power supply in a compact sealed plastic case. The main advantages of devices of this type are compact size, pleasant appearance, tightness and minimum weight. The disadvantages include, of course, high cost, difficult heat exchange due to design features, and power limitation (there are no models more powerful than 100 W).
2. 2. Power supply in a compact sealed aluminum case. It has a lot of advantages, although it is the most expensive and rather difficult option. The main advantages of this transformer are reliability, tightness and durability. The aluminum case contributes to good heat transfer. The device is resistant to negative influence various factors: moisture, sudden changes in temperature, direct sunlight. The main scope of application is the professional production of outdoor illuminated advertising.
3. 3. Open type power supply. most popular and inexpensive option. Most often used for organizing home LED lighting. The main disadvantages are dimensions, twice the previous versions, unaesthetic appearance and lack of protection against direct moisture and dust.
4. 4. Network compact power supply. It is a miniature, simple and inexpensive device that does not require fixed installation. The power of most of these models does not exceed 60 watts. Most often they are used to provide power to LED strip structures, the length of which does not exceed 5 meters. The main advantage is ease of use: the tape is connected to the power supply and plugged into an outlet.

Connecting the LED strip to the power supply

When choosing a power supply, two important parameters must be taken into account: power (depends on the power of the LEDs per 1 mp and the length of the tape) and voltage (usually 12 or 24 V).

Before mounting the LED strip and placing it on the selected surface, you need to connect the strip to the power supply.

We will consider this process using the example of an open type block model. Its body is made in the form of a perforated metal box, through the openings of which air circulates and the radio components and the terminal module with screws are cooled. There are models in which a fan (cooler) is placed inside the case for cooling.

Power supply for LED strip has a marking indicating the purpose of the device and its main technical characteristics. Near each terminal screw there are markings to ensure the correct connection of the wires:

• L - phase, N - zero - this is the input of the power supply. Through these terminals, the device is connected to a 220 V network.
• G - terminal for ground wire. If there is no grounding in the house, this terminal is left free.
• The +V and -V terminals are 12V converted output.

Power supplies of this type are equipped with an on indicator - a green light is on. There is also a special swivel mechanism, referred to as "V adj". With it, you can slightly adjust the output voltage, in the aisles from 12 to 13 volts.

After connecting the tape to the power supply, it is necessary to securely isolate all contacts. For effective and accurate protection against accidental contact, a piece of cable duct of suitable thickness can be used. If this procedure is performed with ordinary electrical tape, then the finished result will look rather unattractive, and when using special protective covers that come with the power supply, it is impossible to ensure the proper level of electrical safety.

Of course, in residential premises it is desirable to install more reliable, compact and outwardly attractive devices in waterproof plastic cases. They are characterized by high electrical safety, therefore they do not pose a threat to children or animals if accidentally touched.

How to calculate the power supply for the LED strip

As mentioned above, when choosing a power supply, you should focus on specifications led strip, which will be connected. The main criteria are power consumption and rated voltage.

12-volt tapes can have different power consumption ratings. This is because they are directly proportional to the power and the number of LED elements on the tape.

For convenience of calculation, it is customary to take as a basis the nominal power of the LED strip 1 meter long. Thus, in order to choose the right power supply, the nominal power of one linear meter of the tape should be multiplied by its total length.

Consider a small example of block calculation for SMD 3528 tape

There is a sealed LED strip SMD 3528, 60 LEDs per 1 meter. The operating voltage is standard - 12 V. The power of this type of tape is 4.8 W / 1 m. Those. 1 meter of tape consumes 4.8 watts. Any tape is sold in reels of standard length - 5 m. In my case, the power of the entire tape will be 24 W (4.8 * 5 = 24).

If you take a power supply with a power equal to the power of the tape, there is a threat of overheating of the PSU, especially if there is no access to it required amount air, for example, when it is located in a limited space under the ceiling.

If the power of the power supply is less than the calculated power of the tape, it simply will not turn on due to the operation of the internal protection of the unit.

Therefore, choosing tape power supply it is necessary to add 25 - 30% of the reserve to the calculated power. We get: 24 W + 30% = 31.2 W. We round up to the nearest standard PSU power - 30 watts.

To connect, I need 3.5 meters of tape (in a nutshell, there will be a semicircle plasterboard frame on the ceiling, a tape will be located around the perimeter of this frame). The power of a piece of tape 3.5 m long is 16.8 W, rounded up to an integer - 17 W.

We take a power margin of 30%, we get: 17 W + 30% = 22 W. We select the nearest block with a standard power of 24 watts.

Correct and uninterrupted operation of the LED strip and the block is possible only if this device has a 25 - 30 percent power reserve, this will provide the power supply with the necessary power reserve for its correct operation.

Before you buy a 12v LED strip power supply, read the basic recommendations for effective selection and purchase based on our seven-year testing practice.

• 1. How to choose the right one?
• 2. Measurement of energy consumption
• 3. Power calculation
• 4. Assembly check
• 5. Voltage regulation
• 6. Main types
• 7. Contact pad
• 8. Fan noise
• 9. Chinese stores

Power consumption measurement

Before choosing a 12v power supply, we recommend that you first measure the real power of the LED strip. It can be 2-3 times lower than the declared one, regardless of the type of installed SMD 5050, 3528, 5630, 5730 LEDs. The numbers in the designation of the LEDs indicate the size of the case; power and luminous flux do not depend on them. Any crystal can be installed in a standard 5630 case, usually they put crystals from 0.09w to 0.5w. Therefore, the actual power consumption may differ by 5 times.
Measurement of real energy consumption will save your finances, it will be possible to buy cheaper by 20-50%. The measurement is correct by connecting the cable at both ends of the LED strip 5 meters long. If you have a segment less than 1 meter long, then it is enough to connect on one side. With a high current of the order of 3-5 Amperes, the resistance of the copper base increases, the power and brightness gradually decrease towards the end. Losses can reach up to 40% of total energy consumption.

Power calculation

The maximum long-term power supply for a 12v LED strip should be with a margin of 15-20%, that is, the calculation is very simple. At best, about 30% is desirable, which will help increase reliability and service life. In full power mode, it will operate with maximum heat and maximum load on electronic components.
The output voltage must be higher than or equal to the declared 12v, 24v. If, when the load is connected, the voltage drops below the specified value, then there is not enough power and a replacement with the best option is required. A good 12v power supply has protection against short circuit and overload. In overload mode, it works at the limit of its capabilities, so overheating or failure of electronic components may occur.

Build Verification

In our laboratory, we test power supplies for 12 volt LED strip of domestic and Chinese brands. Therefore, we are aware of all the problems and shortcomings.
If you are a little familiar with electronics and know how to hold a soldering iron, then I recommend checking the build quality before use. Pay attention to power elements with radiators, these can be transistors, rectifiers, microcircuits in large cases. Check for good contact with the cooling system, add thermal paste if necessary. This will greatly increase the life of the voltage source.

Do not confuse a stabilized voltage source with a stabilized current source, which is also called a "driver". Miniature resistors are installed on the tape, which set the current for the operation of the LED. The driver is used for direct connection to LEDs, such as diode lamps, spotlights, luminaires.

Voltage regulation

Power supplies for 12 volt LED strips can have a regulator to adjust the output voltage, marked "ADJ". Usually the adjustment is within +/-5%. Such a regulator allows you to compensate for the drop in the number of volts in the wires. Its presence is necessary if you connect a load of more than 20-30 watts. Losses in conductors depend on the length and cross section of the wires, such losses are inevitable.
Example, we take into account that at 9.5V the LED strip stops glowing;

1. at the output of the source 12v;
2. cable losses were 0.4V;
3. only 11.6V reached;
4. approximately lose 15% brightness.

Main types

There are 4 main types of transformers:

1. hermetic models IP67 IP68 for rooms with high humidity, cooled by large radiators made of aluminum and its alloys;
2. models with IP20 fan, the price is lower than the first ones;
3. with passive cooling, the case is ventilated due to numerous holes, the maximum load does not exceed 100W;
4. low-power models in a sealed plastic case, like a laptop.

In addition to the common voltage of 12 volts, most often used in everyday life, there are also professional ones for 24v, 36v and 48v. More high voltage used for very powerful LED strips, which consist of several rows. The higher the voltage, the lower the current required for the same power consumption. Allows you to reduce losses in the copper base, the resistance of which greatly increases with high current.
Compared to 12V, the voltage of 24V, 36V, 48V also reduces the cost of the source itself, the price depends on the maximum output current, and not on the number of volts.

contact pad

The number of contacts of the power supply for the 12V LED strip for connecting wires can be 2-5 pieces for each pole. Usually they are connected in parallel, very rarely they have a separation inside. Multiple pins enhance connection convenience, no need to twist wires together. You can check the parallel connection of the contacts of one pole with a multimeter. Measure the resistance between the pins, when connected in parallel, it will be less than 1 ohm.

Fan noise

Silent sources of high power require a large amount of metal for cooling, which increases the cost significantly. A similar one with a fan can cost 2 times cheaper and have more compact dimensions.
Our lab receives a lot of inquiries about noise from fan sources. Manufacturers install small fans with high speeds for cooling, which are quite noisy. Noise is especially annoying in a quiet room, usually in a child's room or bedroom. To get rid of noise, you will need 350-500 rubles. and 30 minutes of time, you need to replace the fan. Fans for computers various sizes from 50mm to 150mm, some models are almost silent. The optimal and reliable option is silent coolers for Arctic Cooling computer cases with dimensions from 80mm to 140mm. They are sold in almost any store, they have been working with us for 5 years, there were no problems with them. We usually install the Arctic Cooling F9 92 cooler at 92mm. It is completely inaudible at RPMs below 1000. RPMs can be adjusted by setting a variable resistor on the positive wire.
Arctic F9 is much larger in size, so it is not included in the 12v, 24v, 36v power supply case. For ease of installation, it is installed outside the case, it is only necessary to increase the hole in place of the standard cooler. Due to the increased size, it pumps more air than the standard one, so no more than 1000 revolutions are enough. The voltage for operation at 900-1000 rpm will be 7-9 volts. It works fully from 5 volts, starts briskly, turns confidently.

Chinese shops

Testing in our lab various models from the popular Aliexpress online store. Some are trying to buy a power supply for 12v LED strips from the Chinese, hoping to save money. Behind the cheapness lies low quality, especially since the Chinese are very fond of deceiving customers and overestimating the characteristics. The main way to cheat is to indicate not the rated power, but the maximum. The maximum is more than the nominal by 20-40%, but at the same time it can work for a short time, no more than an hour. For a nominal period of operation is unlimited, this mode is also called "long-term power". Therefore, we often meet disappointed visitors who bought a 12v power supply on Aliexpress.

IN last years LED strip has become especially popular. Having a low cost and being truly versatile in terms of application, it is successfully used for both decorative lighting and lighting. The main difficulty faced by novice masters is the choice of a power supply for an LED strip (SL). Today we will try to solve this issue.

The principle of operation of a switching power supply

To date, to power the LED strip, blocks are used that use the principle of pulsed voltage conversion. The essence of the operation of this type of power supply is as follows:

1. Mains voltage rectification.
2. Voltage supply to the primary winding of the transformer in the form of high-frequency pulses. They travel at over 20 kHz, and advanced circuits of expensive SMPS operate at frequencies of 100 kHz.
3. The voltage is reduced to the desired level using a pulse transformer.
4. The output stage rectifies and stabilizes the undervoltage value.

For example, consider the classic circuit of a 220 V AC to 12 V DC pulse converter, assembled on a Top242 chip.

Scheme of switching power supply AC220/DC12 V

The input mains voltage is supplied to the rectifier, consisting of a diode bridge BR1 and a smoothing filter C1-C4, L1. The DC voltage obtained in this way is fed to the DA1 microcircuit, on which a high-frequency (up to 100 kHz) generator is assembled, loaded onto a T1 pulse transformer. The principle of operation of the transformer is the same as that of the classical one. The only difference is that it works at a high frequency, but more on that later.

The high frequency voltage reduced to 12 V is supplied to the rectifier (diode D3) and the smoothing filter (C9, C10, L1). At the same time, the same voltage is supplied through the optocoupler U1 to the stabilization circuit built into the DA1 chip. Stabilization is performed using pulse-width modulation (PWM), the essence of which is as follows.

With an increase in the output voltage, the stabilization circuit (PWM controller) changes the duty cycle (duration) of the pulses supplied to the transformer, and its effective output voltage decreases. With an excessive decrease in the output voltage, the duration of the pulses increases. As a result, exactly 12 V is set at the output of the block, which is necessary for proper nutrition LED strip.

What are the advantages of a switching power supply over a transformer one? Since the voltage conversion is carried out at a relatively high frequency, the dimensions and weight of the transformer, and hence the entire unit, are reduced accordingly. Moreover, they decrease significantly - tenfold. For the same reason, the dimensions of the smoothing capacitors are also reduced. PWM modulation, on the other hand, allows you to abandon the classic linear stabilizers that have low efficiency and require bulky cooling radiators.

The result is an extremely compact and reliable block power supply with efficiency up to 95%.

Expert opinion

Alexey Bartosh

Ask an expert

You can often hear the expression "transformer" instead of "power supply", although this is far from the same thing. The power supply, in fact, is a converter that usually changes not only the magnitude of the voltage, but also the type of current. The name "transformer" was originally given to devices that change only the magnitude of the voltage without changing its other characteristics. Nevertheless, the word "transformer" is often replaced by the expression "power supply".

Main selection criteria

When choosing a power supply for SL, you need to pay attention to the following main characteristics:

1. Voltage conversion method.
2. cooling principle.
3. Execution.
4. Output voltage.
5. Power.
6. Additional functionality.

Conversion method

As I said above, the power supply can be transformer or switching. If you need a power supply of relatively low power, then it is better to give preference to a pulsed design. Buying a serious TBP will only pay off with powers of hundreds of watts - UPSs of this power are expensive and often have cooling fans that create noise and collect dust.

Expert opinion

Alexey Bartosh

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

Ask an expert

If you see an inexpensive low-power transformer adapter in the store that suits you in size, then this is also a good option. It is inexpensive and heavy, but not in your pocket to carry it. The main thing is to fit into the project.

Cooling

Cooling can be passive or active. In the first case, the components of the device are cooled naturally, in the second case, a fan serves for these purposes. If the PSU power is low, then it is better to refuse a device with forced cooling: the fan is noisy and, together with the air, sucks in a lot of dust that settles on the units of the unit. Such sources require regular Maintenance and, most importantly, poorly protected from moisture.

Such a unit not only makes noise, but also acts as a kind of vacuum cleaner.

Execution

The degree of protection against the environment depends on the design. If the power supply will work outdoors or in a humid / dusty room, then you will have to choose a dust- and moisture-proof, or even better, sealed design. No holes, slots and, of course, no fans. For difficult mechanical conditions (vibration, shaking, shock, etc.), a device in a metal solid case is perfect. For a normal living space, you can choose a unit in an open casing with many ventilation holes - it will be better cooled.

Sealed plastic power supply (left), open metal protected from dust, moisture, shock power supply (right)

Output voltage

Everything is simple here. SL are produced for 2 voltages - 12 or 24 V. Read on the packaging box or even on the tape itself, what voltage it is designed for. Then select the PSU that has the desired parameters.

This SL is designed for 12 V, which means that the power supply is needed for the same voltage.

Power

On this power supply, both current and power are indicated.

The power of the power supply must be at least 15-20% higher than the power consumed by the tape(s). Everything seems simple, but there is one caveat. Rarely, but it happens that power is not written on power supplies, but only the maximum allowable current is indicated. How to convert it to power? Elementary. Multiply the operating voltage (12V or 24V) of the unit by its maximum current rating in amps and you get the power in watts.

This power supply (photo above) indicates a power of 20 W, a current of 1.67 A and a voltage of 12 V. Let's check for interest: 12 * 1.67 \u003d 20.04 W. Everything converges.

Additional functions

Power supply for SL with wireless remote control and built-in dimmer

In addition to its main work, the power supply can perform some additional functions. There are, for example, devices with built-in dimmers (brightness controls), timers, automatic effects, and even with wireless remote controls. This is up to you, but keep in mind that any additional function is reflected in the cost of the structure.

How to calculate the power supply for the LED strip

If you have a calculator at hand, or even just a sheet of paper with a pen, calculating the power of the power supply will take no more than a minute. Moreover, no special knowledge is required for this, 3 classes of secondary school are enough.

First of all, calculate the power consumption of the SL. To do this, you will need two parameters: the length of the future illuminator and its power density. The length, of course, you choose yourself, depending on the design idea. The specific power of the LED strip is indicated in the accompanying documentation and often directly on the packaging. The units of this parameter are W/m.

Let's say you bought a trunk line with a specific power consumption of 14.4 W/m. This means that each meter of such tape will "eat" 14.4 watts. In this case, the supply voltage of the device does not matter. For backlighting, you decided to use 3 meters of SL. We consider: 14.4 * 3 \u003d 43.2 W. So, your idea will consume 43.2 watts. For reliable operation of the power supply, it must have some (15-20%) power reserve. We add a small margin to the result and get 50 watts.

So you need at least a 50W adapter. Most likely, there will not be such power in the standard series of PSUs, so you buy the closest in value with more power. For example, at 60 watts.

Expert opinion

Alexey Bartosh

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

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You should not choose a power supply with a very large (2 or more times) power reserve. This will increase the dimensions of the structure, reduce its efficiency and cost much more.

If you decide to provide power to several trunk lines with one adapter, then calculate the power consumption of each, and add the results. The tapes will be connected in parallel (see below for the connection diagram), which means that their powers are summed up.

Connecting the LED strip

Connecting the "transformer" (adapter) to the LED strip is quite simple, and is unlikely to cause you any difficulties. Here it is enough to solve 3 main questions:

1. Deal with the polarity of the connection.
2. Pick up the wire of the desired section.
3. Select a wiring diagram.

Connection polarity

Carefully inspect the power supply and find where on its output (output or out) terminals the designation is “plus”, and where is “minus”. If instead of the terminals at the wire block, then they are additionally colored: red “plus”, black “minus”, respectively. Do the same with the LED strip:

Polarity of connection of the trunk line and its power supply

Important! The colors of the wires - red and black - are arbitrary. Many manufacturers do not adhere to this standard, their PSU wires can be of any color, so focus only on the markings.

Wire section selection

Now for the section. The fact that the SL is powered by a relatively low voltage does not mean that the current flowing through the supply wires can be neglected. On the contrary, the lower the supply voltage, the more current will be required to develop power.

If, for example, a current of only 300 mA flows through a 70-watt light bulb for a voltage of 220 V (70\220 \u003d 0.31), then a current of almost 6 A will be required to power a 12-volt LED strip of the same power!

If you connect such a tape with thin wires, then, firstly, voltage will drop on them and the tape will shine in full. Secondly, overloaded wires can heat up and start a fire. Therefore, the cross section of the wire cannot be neglected.

How to find out what current will flow through the power lines? The calculation is easy. To do this, it is enough to divide the power of the tape in watts by its supply voltage in volts. I made this calculation above, showing that a 70-watt 12-volt tape will require a current of 5.83 A. If there are several SLs, then their power must be added before the calculations.

How does wire cross section depend on current? Here, even a calculation is not needed, just refer to the plate below and select a wire with a cross section not lower than the recommended one:

The dependence of the wire cross-section on the current and the length of the line (stranded copper wire)

Current, A	Wire cross-section mm², not less than, with line length
1.6	0.3	0.4	0.6	0.7	0.9	1.1	1.4
3	0.5	0.8	1.0	1.3	1.5	2.0	2.5
4.1	0.7	1.1	1.4	1.8	2.1	2.9	3.6
8.5	1.5	2.3	3.0	3.8	4.5	6.0	7.5
12	2.1	3.2	4.3	5.4	6.4	8.6	10.7
16	2.9	4.3	5.7	7.1	8.6	11.4	14.3
20	3.6	5.4	7.1	8.9	10.7	14.3	17.9
25	4.3	6.4	8.6	10.7	12.9	17.1	21.4

Very often, the diameter of the supply wire is chosen the same as the output wires from the adapter. You can't do that! The longer the supply line, the larger the cross section of the wire should be.

Choice of switching circuit

If there is only one SL, then the connection diagram will be elementary, it is even a shame to draw it:

Scheme of connecting the power supply to one SL

A little more difficult if there are several tapes. Common Mistake novice designer - serial connection of several trunk lines into one long line:

Incorrect connection of several trunk lines to one power adapter

Such a connection overloads the supply rails of the first tape and they, as a rule, burn out. And then the SL can be thrown away. If there are several tapes, only right decision it can only be like this:

Proper connection of multiple trunk lines to one power adapter

Differences between a power supply and a driver

Often the block that provides power to the trunk line is confused with. The power supply and the driver are completely different devices, and in no case should they be confused!

The LED driver is, in fact, a current stabilizer. It limits the amount of current flowing through the LEDs and ensures that this current is stabilized at a given level, regardless of the input voltage. They are not afraid of short circuit, but they can burn out from idling (XX).

The adapter for SL does not monitor the output current: it gives out as much of it as the tape itself requires. The device is engaged only in voltage stabilization, and special current-limiting resistors monitor the current in the SL. If the tape needs, say, 12 V, then the power supply will give out exactly 12, since the high-quality operation of tape illuminators depends on this parameter. Such power supplies are afraid of short circuits, but they feel great at XX due to zero output current.

Thus, confusing the adapter with the driver and putting one instead of the other, you will at best get an inoperable design. At worst, you will lose either lighting device, or a power source - everything will depend on the characteristics and power of the equipment.

So we figured out the power supplies for LED strips. Now you know what they are, and if necessary, you can choose the one you need without outside help.

It's no secret that the LED strip cannot be simply plugged into the network - it will burn out without even a second working. But then how to provide it with the necessary voltage? That's what the stabilizer is for. talking plain language, this is a 12 V power supply for an LED strip, which equalizes the voltage to the required one. But today we will talk about what types they are, how they are arranged and whether it is possible to make such a stabilizing device with our own hands.

Read in the article:

12V power supply for LED strip - what does it do

The voltage regulator does the work of lowering the high mains voltage of 220, 12 or 24 V and converting AC to DC. If you figure it out, then the same actions are performed by Charger any mobile phone, but it will produce less voltage.

But such stabilizers can not only produce direct current at 24 or 12 V. The power supply for a 12 V LED strip can also be a controller. Thanks to complex electronic circuit such PSUs control the flickering modes and color changes of the RGB strip. They are capable of delivering enough power to "light" several separate segments of the LED strip, provided correct selection and connections. But first things first. And first, let's figure out what advantages and disadvantages can be noted in the need to use such power supplies.

Pros and cons of connecting LED strips to a 12V power supply

The main positive aspect of such switching can be called electrical safety - after all, the voltage of 220 V is life-threatening, which cannot be said about 12 V. This advantage covers all minor disadvantages, such as the need to purchase a PSU for the tape and the need to hide it somewhere.

Practice shows that even insulated connections in damp rooms can break down. In the case of installing lighting in the bathroom, this is doubly true. One can imagine what will happen if the phase is on cast iron bath while the person is in it. Surely everyone imagines a hair dryer that has fallen into the water ... If this happens with a 12 V backlight, then the person will not feel anything but a slight tingling, which many will not even pay attention to.

Another advantage is that if the stabilization device comes with the controller, then at 12 V it turns out to be quite compact. You can imagine what size it would be at a voltage of 220 V. Thus, the conclusion suggests itself that the minor inconveniences associated with using a 12 V power supply for LED strips are more than offset by the advantages that such a connection has.

Types of stabilization devices for the light strip

LED strip power supplies can be divided into several types:

• for cooling– active or passive. Active implies the presence in the PSU of a fan that forcibly cools the transformer;
• for execution- it can be a closed, sealed or open case. The latter is mounted only in dry and dust-free rooms;
• by functionality- an ordinary power supply unit, with a dimmer, a controller, or a combination of all these functions.

Of course, the most interesting power supply for LEDs with an RGB controller. This abbreviation in the marking of both the PSU and the light strips means that the device is multi-colored. It came from the first letters of the name of the main three colors on English language, which form the remaining 4. Such controllers are most often equipped with an IR receiver for the ability to control colors using a remote control. This allows you to turn the backlight on and off, as well as switch its shades from anywhere in the room.

Often a dimming function is also built into it - a slow dimming of lighting - which is also very useful.

Power supplies in a sealed case are installed in rooms with high humidity, such as a bathroom, bathroom or kitchen. At the same time, a good controller is able to switch the backlight from one line to another as needed.

It is important to know! To ensure the uninterrupted operation of the LEDs, it is necessary to choose the right power supply not only in terms of voltage, but also in terms of power. The correct connection is also very important, which we will discuss in more detail below.

How to calculate the power supply for the LED strip

Such calculations are not difficult. All that is required is to calculate the total power consumption of a strip of light, and then add a margin of 20%. For example, let's try to calculate the required power supply for LEDs. Let's take a tape with SMD3528 elements, 3 m long and with a frequency of 120 pcs/m. For such a strip, the power consumption of all diodes in a segment of 1 m will be equal to 28.8 watts. We get 28.8 × 3 + 20%, which will be equal to 100.68 watts. The closest to this indicator will be a 150 W PSU, so it will be needed. Although a 100-watt unit will work quite normally with such a band.

These calculations are very important. After all, if you do not understand how to choose a power supply and do it wrong, it can simply burn out. And this is money thrown to the wind and wasted effort on installation.

Options for connecting the LED strip to the power supply

There are only two ways to connect this lighting equipment, like any other - this is in series and in parallel. But here the installation option plays a very important role. If you choose the wrong switching method, you can burn the contact tracks through which the voltage passes from one LED to another.

The choice of mounting scheme depends on the length of the strip sections. On each of them there are places for the cut. Usually the distance between them is 3 LEDs. And if the tape segments total more than 5 meters, then it can no longer be connected in series. We will figure out how to properly install and connect.

Serial connection - in what cases it is performed

Such switching is a connection in which power enters the second consumer, passing through the first.

If the segments are short enough, then they must be connected to each other in series. This will increase the length of the strip to the required. But at the same time, it should be understood that the total final length should not exceed the same parameter of the new LED strip. In other words, if it was sold in a 5 m coil, then after splicing, the final size of the strip should be less than or equal to the original one.

If the length is exceeded, there is a danger of burning out the conductive paths between the light diodes due to the passage of high power current through them. In this case, the tracks between the first elements are burned out first. When they are removed between the next, and so on until the length of the strip is normal for proper operation.

Parallel connection of the strip and how to do it

Parallel connection is called switching, in which power from the source goes simultaneously to two or more consumers. However, they are not connected to each other.

If it is required to connect a strip, for example, 9 m, then installation according to parallel circuit. To do this, we take segments of 5 m and 4 m. The wire leaving the power supply is switched in the same order with both bands. It turns out that power from the stabilizing device is supplied simultaneously to both segments. This allows you not to overload the tracks going from one LED to another.

It is important to know! With this installation scheme, do not forget about the operating power of the stabilizer. It consists of the total consumption of two segments.

In general, it is necessary to understand that when connected in parallel, the voltage drop remains unchanged, but the current consumption increases - this is quite important to know when installing such lighting equipment.

How hard is it to make a voltage stabilizer for a light strip

It should be noted that the assembly of such a PSU from scratch is only possible for a professional radio electronics engineer. But do not think that without a certain qualification it is impossible. After all, it is quite possible to use a factory-made transformer for this purpose. A good option would be to use a power supply from a computer. The main task here is to choose a device suitable for the LED strip in terms of power.

Before choosing a power supply for the strip, we determine the required voltage. If 12 V is needed for the diodes, then the output from the transformer should be from 12 to 20 V. It is quite convenient if you have a ready-made two semiconductor rectifier at hand, which is necessary for the stabilizer to work. And the third thing you need is a microprocessor. The most successful solution would be to use the 7812 chip.

By putting all the details together, you can get a power supply with an output current of 1.5 A, which is quite enough for an LED strip. Of course, it is unlikely that you will be able to assemble a controller for an RGB strip with your own hands, but there is a trick here. It is quite possible to use a block from an old Chinese garland, the parameters of which are indicated on the case. In this case, based on the power it gives out, you can calculate the required strip length and connect it to the controller, thus achieving the ability to switch between flicker and color modes. The only inconvenience will be that switching can only be done with a button on the block, which means that it will not be possible to hide it.

Another fairly simple way that does not require knowledge of radio electronics is to connect a light strip through a controller from an LED chandelier with a remote control. All technical data for calculating the length of the tape by power can be taken from the documentation for.

Is it possible to repair the voltage regulator for light diodes

This work is quite feasible even for home craftsmen who do not have certain skills and knowledge. The main task here is to determine which of the parts needs to be replaced. The main parts that can fail are the microprocessor and the rectifier bridge. Transformers rarely burn, but this happens. Let's try to understand how to deal with the breakdown.

It is worth starting the check with the simplest nodes, as in any equipment. Having opened the cover of the group of contacts, we set the switch of the multimeter to the position of alternating current 750 V (on some devices 1000 V) and applying power to the unit, we check whether it is supplied to the input contacts of the transformer for the 12 V LED strip.

Very important! When performing all operations with the transformer, you must be extremely careful and accurate. Do not touch live parts with unprotected parts of the body. Remember that defeat electric shock dangerous to life and health.

If voltage is supplied to the unit, then the supply wires are in order. We check the voltage at the output of the transformer. As already mentioned, it should be from 12 to 20 V. The next step is to check the diode bridge. To do this, set the value of the multimeter switch to a constant voltage with a value slightly higher than the output of the transformer. When touching the contacts at the output of the rectifier bridge, the device should show the same values ​​\u200b\u200bas the previous step (only slight downward deviations are possible).

If, after performing these steps, it becomes clear that the step-down transformer and diode bridge are working properly, this means a problem in the microcircuit. After a malfunction is identified, it will be necessary to replace the failed part of the circuit. The new one should have the same parameters.

Where to buy a power supply for LED strip

Buy necessary equipment These days, you can get it at any electrical supply store. Fortunately, the range of such products is now quite wide. You can also order it online. However, it is worth as carefully as possible to study the reviews of those who have already used this resource. You should especially beware of purchasing such goods on Chinese resources. Here's what one netizen has to say about it.

vitas77, Russia, Moscow: The driver went for almost three weeks, and then the day came when I found the long-awaited package in my mailbox, everything was packed quite well, the driver itself with soldered wires. I connected the LEDs, according to the description, connected the power, everything worked, but my joy did not last long, the driver warmed up noticeably and eventually refused to work. The device has not worked more than an hour. Bottom line, time and money wasted. At the end of everything written, I want to warn you, before ordering, contact the seller and find out as much information as possible.

More on Otzovik: http://otzovik.com/review_2975618.html

Let's try to consider how prices differ when purchasing such power supplies in regular stores and on Internet resources. Let's start with real sellers of RGB controllers (the last digit in the model name means the number of channels).

Make and model	Total current, A	Channel current, A	Voltage, V	Number of programs	Average cost, rub.
iMLed2	30	15	5-25	23	1200
iMLed4	30	20	5-20	23	1500
iMLed6	30	15	5-25	20	1900
iMLed9	80	15	5-20	20	3000
iMLed16x3	32	2	5-23	20	3300
iMLed16	80	15	5-20	20	3500

As you can see, the cost of such devices is not too high. But what about online stores? Let's try to find devices with similar characteristics.

Make and model	Total current, A	Output power, W	Output voltage, V	Number of programs	Average cost, rub.
CRIXLED CRCN N18-RFS-12	18	216	12-24	14	1800
ASD LS-CB-12	12	144	12-24	20	500
LSC 003	2	24	12-24	No	500
LSC 008	4	144	12-24	3	1500
RGB 144W	12	144	12	14	1200
Ecola LED strip	6,6	1500	12-36	24	2000

Generally speaking, the prices do not differ too much. This means that there is no point in taking risks by buying a “pig in a poke” over the Internet. Indeed, in this case, it will not be possible to make a claim to the seller, and the guarantee, most likely, will be absent.

Finally

A power supply for an LED strip is necessary - this is clear to everyone. The main thing is to choose one that fits in all respects to your light strip. And if all the calculations are made correctly, then such a voltage stabilization device will work for quite a long time.

We hope that today's article was useful to our dear reader. In the discussions below, you can always ask questions about a topic that is not clear. Write, communicate, share your experience. And our team will try to answer your questions as fully as possible and help you as much as possible.

Finally, we suggest watching a short video on the topic.

Video: connecting LED strips