Choosing a power supply for LED strip

Recently, LED strips began to be used for lighting private houses and apartments. This is not surprising, since their pleasant and warm glow complements the atmosphere of home comfort. Various types of ribbons are sold on the market, and for each of them it is necessary to choose the right power supply.

LED strip features

LED strip is a strip of flexible material with insulating properties, which is equipped with two conductive copper foil busbars, LEDs and resistors.

A flexible strip with LEDs installed creates a bright light source up to 5 meters long

LED strip consists of sections of three diodes, each of which is connected to a power source in parallel

LED strip can be cut into fragments with the number of LEDs, a multiple of three

With the correct connection of the wires to the power buses, a voltage will begin to flow to the section or cut section of the tape, which will cause the current to pass through the LEDs. Due to the peculiarities of its design, under the influence of current, the LEDs will begin to emit a luminous flux (glow). It should be noted that the level of luminescence directly depends on the magnitude of the current. If the current value is too small, the diode will emit a dim glow or will not glow at all, and if it is too high, it will quickly deteriorate and burn out.Basically, the average current for diodes used in LED strips is between 15 and 20 milliamps (mA).

LED Strip Classification

A wide variety of single-color LED strips led to their classification according to several basic criteria. These criteria will be described below.

By type of LEDs used

The main distinguishing feature of LED strips is the type of diodes used in the manufacture of the product. Basically, single-color LED strips are made on the basis of SMD 3528 and SMD 5050 diodes.

The abbreviation SMD means that this electronic component is intended for mounting on the surface of a printed circuit board. Full marking also includes the dimensions of the product in millimeters: for example, for the SMD 3528 LED, the length is 3.5 mm and the width is 2.8 mm.

LED density

LED strips are also divided by the number of elements (diodes) used in one meter of the tape, which in technical circles is called density. It is worth noting that the number of LEDs used in the manufacture of one meter of tape affects the total power of the product, as well as its light performance (degree of illumination).

The denser the LEDs are, the more they fit on a piece of tape and the brighter the light will be

The power of LED strips, like other electronic products or equipment, is measured in watts (W). The value of this parameter is determined by the dimensions of the diodes and their density. For example, a typical LED strip made on the basis of SMD 3528 consumes:

• 4.8 W if 60 diodes are installed on each meter;
• 9.6 W, if the density of the LEDs is two times higher - 120 diodes per meter;
• 19.2 W, if the diodes are in two rows, and their total number per meter is 240 pcs.

For a tape based on SMD 5050, the power consumption will vary as follows:

• 30 diodes / meter - 7.2 W;
• 60 diodes / meter - 14.4 W;
• 120 diodes / meter - 28.8 watts.

It is easy to see that for the same type of tape, the power consumption is directly proportional to the number of LEDs installed. This is understandable - each diode consumes the same amount of watts.

Choosing a Power Source for LED Strip

In order to enjoy pleasant and unusual lighting, you should choose the right power source. This step is very important, because if the wrong choice of LEDs can burn out, and the product will fail.

Factors affecting the choice of power supply for LED strips

When choosing a power source (unit) for LED strips, you should focus on the following parameters:

1. Tape supply voltage.
2. Its power consumption.
3. The necessary degree of protection of the equipment from moisture.

As an example, take the SMD 3528 LED strip with a length of 6 m (60 diodes / m).

LED strip voltage

As mentioned above, all LED strips are divided into products that are powered by 12 V and 24 V, respectively. Naturally, the output voltage of the source must be equal to one or another value. So, in order to find out the voltage supply of the LED strip:

1. We open its technical characteristics and look for the parameter of interest.
2. We see that the tape is powered by a voltage of 12 V.

In accordance with the found voltage value and carry out the selection of the power supply.

Power consumed by LED strip

To calculate the power of the power source, you should again refer to the technical characteristics of the LED strip. This time we are interested in the value of power consumed per meter of product (P_tapes= 4.8 W / m).

1. According to the condition, it is necessary to provide power to the LED strip 6 meters long, which means in order to find the full power that the strip consumes (P_rub) we use the following formula: P_rub= P_tapes × L = 4.8 W / m × 6 m = 28.8 W.
2. It should be noted that the power supply for this parameter should be chosen with a margin (about 30–33%). Therefore, we need a 12 V DC source with a power of 28.8 x 1.33 = 38.3 ≈ 40 watts.

Moisture protection

This is another important factor to consider when choosing a power source. When choosing this criterion, you must first determine the location of its installation. If you plan to organize LED lighting in the bathroom, you must choose a power supply that has moisture-proof properties (IP 65 or IP 68). In a typical dry type living room - bedroom or living room - you can use a simple interior source.

However, in order for the source selection to be 100% correct, in addition to the factors described above, you should select the appropriate type based on its advantages and disadvantages.

Types of Power Supplies

There are currently four types of power supplies for LED strips.

Table: Advantages and Disadvantages of Different Types of Power Supplies

LED Strip Power Supply Manufacturers

The most popular and sought-after manufacturers of power supplies for LED strips are:

1. Cool Neon. It produces an extensive line of LED transformers that can be used to solve various goals and tasks. The company's products are equipped with built-in protective devices and can be used at temperatures from -25 to +45 ° С. The average service life is more than 25 thousand hours.

The Cool Neon product range includes both open power supplies and sealed models that can operate at low ambient temperatures

• Lightech. It produces power supplies that ensure high stability of LED products including tapes used at temperatures from -30 to +50 ° C. The company's products are mainly designed to operate for 50 thousand hours or more. Features of these models are:
  1. Wide range of input voltages.
  2. Resistance to mechanical shocks and vibrations.
  3. Overheat protection.
  4. Resistance to impulse noise in the network.
  5. Built-in short circuit protection.
  

  Lightech launches sealed power supplies in plastic enclosures for high output stability

• UnionElecom. The company produces sources that are of high quality and reliability. They are designed to operate in the range from -40 ° to +50 ° C, which allows you to install them not only indoors, but also on the street. For street power supplies, the service life is over 40 thousand hours, and an individual warranty for a period of 36 months also applies. Features of UnionElecom equipment:
  1. Compact size.
  2. IP 68 protection.
  3. High quality assembly, which is made exclusively on the territory of the manufacturing plant in South Korea.
  4. The optimal price-quality ratio.
  

  Hermetic UnionElecom power supplies are compact, with the highest degree of moisture protection of the aluminum case (IP68) and an affordable price

Transformer power calculation

The main parameters that are used when calculating the power of the power source are: linear power consumed per 1 meter of tape (P_tapes) the number of diodes at the same distance and the output voltage is 12/24 V.

Above, we have already touched on the topic of power calculation using the example of an SMD 3528 LED strip with a length of L = 6 m (60 diodes / m and P_tapes= 4.8 W / m) and a supply voltage of 12 V. According to the calculation results, it turned out that all this tape consumes P_rub = 28.8 watts_. For greater clarity, duplicate the previous calculation here:

1. P_rub= P_tapes × L = 4.8 W / m × 6 m = 28.8 W.
2. In order for the power supply not to overheat, the power should be calculated with a margin (a margin of 33% is taken). We use the formula: P_BP= P_rub+ 33% = 28.8 + 9.54 = 38.3 watts.
3. Based on the calculation, we select the power supply from the standard line of the manufacturer of interest, for example, 40 watts.

Using similar formulas, we calculate the power for the LED strip SMD 5050 120 LED (120 diodes per meter). This product has the following parameters: P_tapes= 28.8 W, density 120 diodes / m, supply voltage 24 V, tape length L = 2.5 m (suppose we cut the required amount from a standard length of 5 m).

1. P_rub= P_tapes × L = 28.8 W / m × 2.5 m = 70.2 W.
2. P_BP= P_rub+ 33% = 70.2 + 23.16 = 93.4 watts.
3. In this case, select a 100 W power supply.

It is worth noting that using these formulas, you can easily and simply calculate the power of the power supply for LED strips with any parameters.

Features of installing a power supply

Power supplies for LED strips are usually installed in accordance with the structural diagram that is included in their package. Basically, before installing the transformer, the LED strip is cut into sections consisting of the required number of diodes.

Cutting points are indicated by two pairs of contact groups (from each end of the section) and a marker in the form of scissors. The power supply is connected parallel to the sections. During the connection, it is necessary to observe the polarity (connect the terminals of the power supply with the designation "+" and "-" to the corresponding contacts of the tape), while keeping in mind that the output voltage of the source must not exceed 12 or 24 V (nominal voltage of the tape). The location of the power supply does not affect the functionality of the device, but it must be selected for aesthetic reasons.

In practice, two schemes are used to connect the LED strip to the power supply.

Connecting LED strip to one power supply

Most often, an LED strip is a one-piece five-meter length that is wound around a plastic reel. As a rule, from the outside - to the end that is not unwound on the reel - the wires necessary for connecting to the power supply are connected to the tape. If after the purchase there was a lack of connecting wires, then you should take any stranded wires of red ("+") and black ("-") colors, measure the desired length, which should be enough to reach the terminals of the power supply, and solder them, previously stripping and tinning both ends.

1. We serve the wires using rosin and tin, and by soldering we connect them to the tape tracks. In the process of soldering, a low-power soldering iron should be used and the connection made quickly enough, since there is a possibility that the LEDs can be damaged due to the effect of elevated temperature.
   

   The wires need to be serviced quickly so as not to overheat them and not damage the LEDs

2. After that, the free ends of the wires (not soldered to the tape) are connected to the power supply, observing the polarity.
   

   The red wire from the LED strip (“+”) must be connected to the “+ V” terminal, and the black (“-”) cable to the “-V” terminal; the mains voltage is connected to the terminals “L” and “N” (“L” - phase, “N” - zero)

Connecting two LED strips to one power supply

As an example, consider the following option: the installation and connection of an LED strip is planned, the length of which is 8 meters. The problem is that finding a piece of tape of this length is quite difficult, because basically LED strips are sold in coils of 5 meters. However, it still takes 8 meters, and what to do?

If you need to connect several pieces of LED strip with a total length of more than 5 meters, this can only be done in parallel

Everything is quite simple. We perform the following actions:

1. We purchase two coils with LED strip, and one piece is left whole (5 meters), and from the second we cut 3 meters and connect them. In order to cut the tape we take ordinary scissors and look for a line along which we will cut a piece of the desired length.
2. Next, we clean and service the contact pads of both pieces of tape (on the same side).
3. We take four two-wire wires (two red “+” and two black “-”) and also prepare (we clean and tincture).
4. Solder to two pieces of tape. The free ends of the wires coming from a five-meter piece are soldered (screwed) to the terminals of the power supply (“+ V” and “-V”), and to the terminals “L” and “N” we connect the wires of the network cable.
5. Next, on the wires that are connected to a five-meter piece of tape, remove small pieces of insulation. Then we trick them and solder wires from a three-meter piece to them, thereby connecting both pieces of tape in parallel.
   

   If the corresponding wires from each tape are brought to one point, a parallel connection is obtained

Video: connecting and installing LED strip - 3 main rules

A variety of choices of LED strips will help to realize any dream and create a truly beautiful lighting that will emphasize any room. The use of LED strip as a lighting device will give the house additional comfort and warmth. However, before you start creating an LED lighting system, you should familiarize yourself with the types of products and study the rules for selecting power so that the whole system works and pleases the eye.