How to choose a transformer for 12 and 24 volt LED strip

How to choose a transformer for 12 and 24 volt LED strip


LED stripes can be seen more often in our daily life. They can have different colors and power. They decorate the living quarters, the facades of shops and boutiques, Christmas trees and trees. Therefore, many people are interested in the question of how to connect the LED tape, which is powered by a voltage of 12 and 24 volts and how to correctly calculate the required power of the power transformer.


  • 1Features and characteristics of LED strips
    • 1.1Kinds
    • 1.2Benefits
  • 2How to choose the right power supply for LED ribbons
    • 2.1What you need to know about power transformers
    • 2.2Types of power supplies by characteristics
    • 2.3Modern transformer manufacturers
  • 3Calculation of power supply transformer for 12 and 24 volts
  • 4Transformer installation features
  • 5Correct connection with diagrams and photos
    • 5.1Connect a tape longer than 5 meters
    • 5.2How to properly connect RGB - tape, controller and amplifier
  • 6Video: how to connect the LED - tape to the transformer

Features and characteristics of LED strips

LED tapes are long flexible boards with contacts on which SMD diodes are located at a certain distance from each other. In order to limit the current flowing through the tape, special resistors are soldered on it. Designers and designers very often use LEDs to create a special style of interior, visual expansion of space of a premise, concealment of light sources at installation tension or pendant ceilings, etc.

LED Reel Coil


LED ribbons can be of various types:

  1. Self-adhesive. In order to glue it, you just need to remove the sticky layer and attach it to a flat surface area, curving in any geometric shape.
    Self-adhesive LED tape with a sticky base
  2. Wicked. For fixing ip68, plastic clips are used.
    Bezklevaya LED strip
  3. Waterproof ip65. They are used for lighting installation in rooms with a high humidity level.
    Moisture-proof LED strip
  4. Sealed with ip67 and 68. Are intended for the device of illumination in premises with the raised level of humidity, and also under water in pool.
  5. Open. They are used to create lighting in rooms: under the ceiling, on walls, etc.
  6. Multi-color RGB. Tapes are able to change their color by means of a special controller.
    Multi-color LED strip
  7. White or monochrome. The degree of their brightness is regulated by means of a special dimmer.

Tapes with LEDs can have a different number of diodes of different types. The most popular are the LEDs of the brand 3528 and 5050. The numbers indicate the dimensions of the diodes x, mm and 5x5 mm. The first are equipped with a plastic casing with a single crystal. The latter also have a plastic housing in which there are 3 crystals, so these LEDs shine much brighter.

In addition, they produce two-row belts with a large number of diodes. Currently, in stores you can buy new types with special chips smd2835, which have improved light characteristics. Due to their low cost and high light output, they are rapidly gaining popularity. Since the LEDs in such tapes operate in a safe mode with a reduced current, this fact allows them to be used for a long time without loss of brightness. They may well work out their 5, 00 hours, which were claimed by the manufacturer.

Double-row LED strip reel

LED tapes are low-power, so they consume a minimum amount of electricity. Currently, there are many species with different types of power W / m; 7.2 W / m;, W / m; 1, W / m, etc. LEDs give so powerful a bright light that they can be used not only as additional lighting, but also as the main source of light. For this purpose, special tapes of the type LED-TED are used, which are the brightest.


  • Minimum power consumption;
  • Service life is more than 10 years;
  • The ability to fix the tape at any angle and give it a different geometric shape;
  • Uniform distribution of lighting throughout the perimeter of the room;
  • A wide range of colors;
  • High degree of fire safety and ecological compatibility;
  • LEDs do not have mercury in their composition and produce a minimum amount of heat;
  • Do not change their color during the whole working period;
  • Do not have radio interference.

How to choose the right power supply for LED ribbons

A transformer or power supply for LEDs is necessary to ensure their operation. A direct power supply of 220 volts is not suitable for this type of lighting, since when the tape is plugged into the network it will simply burn out. Therefore, all power supplies (adapters) are mainly produced at an output voltage of 12 V. Also, there are options with a voltage of 24 and 36 V.

Reducing power supply for LED strip

In principle, any LED-tape can work completely from batteries or car battery, but the duration of its operation will be limited.


Therefore, it is necessary to select the power supply depending on the capacity specified by the manufacturer. It will indicate the degree of power in watts or amperes. It is selected only after the acquisition of the tape itself.

What you need to know about power transformers

The transformer must be selected according to parameters such as:

  • Supply voltage;
  • Power consumption;
  • Degree of waterproofness.

By its cooling system, transformers can be active and passive:

  • With the active system, the case of the device is equipped with a fan, which significantly reduces the dimensions of the device, and also increases the degree of its power. The disadvantage is the noise of the fan, which will only increase with time. Literally after one or two years, you have to clean the inner surface of the transformer, fan the oil with a special oil or change it.
  • With a passive system, the case of the device is powered by a laptop unit. Also it can be top covered with a lid.

According to their functional characteristics, the transformers are:

  • Simple. Provide the ribbon with only food.
  • With built-in dimmer.
  • Equipped with a remote control for working with a radio channel or infrared channel.
  • Multifunction with dimmer and remote control. This device allows you to limit the use of a large number of transformers in various locations.

Since the LED ribbons in their advantage are of two types at 12 and 24 volts, the transformer should give out just such a voltage.

The degree of moisture resistance of the device depends on the place of its future installation. If you plan to install it in a dry place, you can purchase a conventional interior transformer. For a bathroom, sauna or pool, you need to choose a device with a waterproof housing.

Types of power supplies by characteristics

By their type of execution, the blocks can be:

  • Made of black plastic with specified specifications. The most optimal option.
  • With hermetically sealed aluminum housing for rooms with a high degree of humidity. The unit is not afraid of condensation.
  • The block with the metal case, small apertures for air circulation and a contact platform. Used only in dry rooms, installed in a place inaccessible to people and closed from dust.

Transformer in an impermeable body made of durable plastic has a fairly compact dimensions, accurate appearance and light weight. The high cost of the device, the complex heat transfer, which is due to the design of the transformer and the limitation of power - the main disadvantages of the unit.

Power supply for LED ribbons in plastic housing

The transformer in the aluminum rugged case has a lot of advantages, although it is the most expensive model and quite heavy. This is a reliable, sealed and durable device that can provide a good degree of heat transfer. Has a high resistance to temperature changes, moisture, as well as ultraviolet radiation. It is usually used for the device of external facade advertising of shops and other public buildings.

Transformer for LED strips in aluminum housing

An open transformer is considered the most popular and affordable device. It is mainly used for lighting devices in apartment houses. The disadvantage can be called a large size, an unattractive appearance and the absence of a protective enclosure.

Outdoor transformer for LED strips

A network transformer is a small and simple device that does not provide a fixed installation. The power rating of most of the models is not more than 60 watts. Often used for a supply source of LED strips, not more than five meters in length. The main advantage of the power supply unit is the ease of use and the ability to connect to a conventional network.

Network transformer for LED strips

Modern transformer manufacturers

Currently, there are a large number of manufacturers of step-down transformers, which are designed for connecting LED-tapes.

One of the most famous is the Arlight brand, which offers consumers a transformer made in a metal, plastic, protective casing. All units of this manufacturer have special protection against short circuit and overload. The metal case helps to efficiently remove heat. Inside the housing is encapsulated with a compound, it has a protection class of IP 65 and 67. During operation they do not make much noise. They have power levels from 20 to 3000 W.

Transformer Arlight in an aluminum case
  • Devices in the plastic housing are also filled with a compound. They have IP65 protection class, reasonable price, small dimensions and excellent degree of noise insulation. Power from 5 to 2000 watts.
  • Unsealed blocks in the metal casing have an excellent price-performance ratio. But they are not recommended to be installed in living rooms, as during work they can create a large number of noise effects. The power of devices from 15 to 2000 watts. The latter have a built-in cooling fan.
  • Network adapters are available in plastic enclosures. The output wire has a connector. Used to connect small pieces of LED tape to the network. Power varies from 4 to 84 watts.
    AC adapter for LED strip
  • DIN-rails are designed for installation in special flaps. But since the tape is at a remote distance, when using it, one must take into account the degree of voltage drop and acquire a wire of the required cross-section. Power ranges from 50 to 240 watts.
  • Also Elvan brand can offer the same set of lowering blocks, which are distinguished by an affordable price and high quality of execution.
  • If you want to connect a tape with a small power, then the Electronic Light CS 31350M device will help. This is a small device that is small in size and easy to connect. Can work in a wide voltage range (from 110 to 240 volts).
Small transformer for LED light strip Electronic Light
  • The transformer brand Brille DR-15W is perfect for feeding a small area. Has a nominal output power of 15 watts, operating voltage from 170 to 250 V. Housing dust and waterproof IP67.
Power supply for LED strip Brille
  • A small transformer Brille DR-75W can be fastened anywhere in the room. It has a voltage input of 110-120 / 220-240 V and 12 V at the output. Degree of protection IP20.

Calculation of power supply transformer for 12 and 24 volts

Often LEDs require the presence of a DC voltage of 12 or 24 volts, so we need calculate the power of the device that will convert the alternating voltage (220 V network) to a constant (12/24 AT).

We will consider the power calculation using the example of a simple SMD 3528 60, W / meter. Let's say its length is 16 meters.

Since the voltage manufacturers indicate on the packaging or on the tape itself, the feeder should provide this voltage for work.

  • On our tape, the operating voltage is 12 volts, so we need to purchase a transformer with this voltage with a certain degree of power.
  • In order to make the correct calculation, we need to know the power consumption of the diodes, W / meter.
  • We need to multiply 16 meters by the power, W (16x, = 7, W).
  • Since the device must necessarily have 20 or 30% of the power reserve, then to calculate the required power, we need to multiply the result by. (7, x, = 9.6 W).
  • But since the power supplies do not sell at 96 W, we will have to purchase a 100 W transformer.

If the LED tape we will be mounted outdoors or in a room with a high level of humidity, it is best to purchase a moisture proof device with a sealed housing such as IP65, 66 or 67.

Transformer installation features

Installation of transformers is made according to the scheme, which must be applied to the LED strips themselves. Usually they are cut into pieces by three diodes in each group. The design assumes a current-limiting resistor. But in some cases there may be 5 to 10 diodes on one part.

The cut location is indicated by contact groups on both sides. LEDs are connected in groups in a parallel way. The transformer can be installed anywhere in the room, but the polarity "+" or "-".

When buying a transformer, you need to make sure that it is really designed for LEDs, since some people mistakenly choose the devices that are used for halogen lamps. Although they can lower the voltage to the required 12 volts, they give an alternating current at the output, since a constant current is required for the operation of the LED ribbons.

  • The power supply should be equipped with a soft start system, which will significantly increase the life of the tape.
  • The device must have about 20-30% of the power reserve.
  • Install recommend in a place where it can be easily reached.
  • If you install the unit in a small room, it will overheat, which will lead to a breakdown.
  • It is important to consider the degree of protection of the unit

Correct connection with diagrams and photos


Since the ribbon with diodes can work from a voltage of 12 or 24 volts, we need to connect a lowering unit (transformer) to it. On the one hand, it is connected to the electrical network in 220 volts, and from the second side to the ribbon board.

It is necessary to keep in mind that two different colored wires are located at the output of the transformer. Also, the tape has two different wires - red and blue (sometimes black).

Red means "plus and blue means "minus". Therefore, when connecting the tape, the specified polarity must be observed. Plus goes to plus, and a minus to a minus. In the event of an error, the device will not turn on.

Scheme of connection of the transformer to the LED strip

Connect a tape longer than 5 meters

Many people make the mistake of starting to attach pieces of tape to each other. At the end of the first tape, connect the beginning of the second. But it's not right.

Wrong connection of LED strip to power supply

The second piece of the LED ribbon will shine a lot dimmer, and the final diodes are completely dull. With a low-power tape, such as SMD 3028, where 60 diodes are located, the brightness will be approximately the same. But along the line of tracks there will be a current much more than a worker. They will be greatly overheated, and this will have a detrimental effect on the diodes. Using such a scheme significantly reduces the life of the tape. In this case, it is necessary to use the scheme, which is shown below.

The scheme of connection of two series diode tapes to one power unit

It is designed for a single power supply, where the power of the device should be equal to the sum of 2 tapes or more.

In order for the required voltage to be brought to the second ribbon board, it is necessary to add one more wire to the output of the device for elongation. The second end is connected to the 2 tape. As a result, the current will flow along the wire itself, and not along the conductive lines.

The cable cross-section for elongation should be sufficient to avoid voltage loss. Usually take a wire five meters in length, a millimeter in cross section. Installation is made in a niche, next to the first piece of tape.

This scheme is used if you can hide a large transformer. And if not, then recommend to apply the scheme a bit more complicated. In this case, the wire for the extension of the chain (0.75 mm) is connected to the electrical network of 220 volts and is conducted to the transformer of the second tape.

The scheme of connection of LED strips with two power units

The installation of the tape in this way is somewhat complicated, since a second power transformer is required, but in this case the power of the devices is reduced by about half. Their dimensions are also much smaller.

How to properly connect RGB - tape, controller and amplifier

A multicolor LED tape is connected as well as a single-color tape, but in this case a special controller must be installed between it and the transformer. They come in different types and differ in their appearance, power level, color management programs and other parameters. But the principle of operation is the same for everyone: two wires from the transformer came to the controller, and 4 went out to the LED-tape.

Connection RGB controller for LED strip

All controllers have a similar connection scheme. The connectors are labeled "V +" and "V"-". The red wire connects to the positive terminal, and the blue or black wire to the negative.

Connectors for connecting a multicolor ribbon are indicated in Latin letters:

R is the red wire.

G - green wire.

B-blue wire.

V +-general purpose wire. Color can be any.

It is important not to confuse the tape wires. In principle, nothing will happen, but in this case you can press the red button on the remote control, and the blue color on the tape will light up.

Remote control panel for the colors of the LED strip

You can not connect two parts of a multi-colored ribbon sequentially, since the conductive paths for this are not calculated. The method of elongation is the same as for a single-colored tape.

Scheme one.

The scheme for connecting a multicolor RGB tape to a single transformer

To connect, we need a wire with 4 cores (, millimeter) and a length of five meters. We will connect an RGB ribbon with thirty diodes per 1 meter. But since it has a very dim glow, it is usually used very rarely.

A ribbon with 60 diodes can also be connected according to the above scheme, but a transformer and a controller with a doubled power level are required.

Let's calculate the results. Two multicolor ribbons can consume 140 watts. A transformer with such a power degree is quite heavy and big, so it is quite difficult to hide it in a niche under the ceiling.


A controller with the same degree of power breaks down very often. Although manufacturers indicate that such devices are rated at 140 watts and are capable of pulling 10 to 15 meters of diode tape, but, unfortunately, they are short-lived.

Therefore, such a device must be purchased with a double capacity reserve. In our case, it's 280 watts. But since there is such a device is not cheap and it is difficult to find it, so we apply the scheme indicated below.

Connection scheme for LED multicolor ribbons with RGB amplifier

Here we use a second transformer and an RGB amplifier, to the input of which we connect the end of the first LED tape, and connect the beginning of the next one to the output.

The colors of the wires are important not to mix up, since each of them is connected to a certain connector. We connect the wires from the transformer to the contacts.

Connecting an RGB Amplifier to LED Strips

This scheme is somewhat more complicated, but at the same time:

  • Transformers are much smaller in size.
  • It is possible to use almost any type of controller.
  • The number of tapes connected is almost unlimited.
    Connecting two LED strips to transformers and amplifiers

Video: how to connect the LED - tape to the transformer

The installation of any LED tape seems to many people a rather difficult task. But if everything is done correctly and according to the manufacturer's instructions and the scheme, you can choose a power supply and connect the tape yourself without involving specialists.

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