Power supply unit for LED strip 12V - device for connecting the backlight to the mains

Tags:Lighting

In interior design LED lights became widespread, because with its help certain zones and decorative elements are distinguished, and also peculiar accents are made. Its main component is the power supply. The corresponding adapter is used for 12V LED strip.

Demonstrating a small 60W device

The content of the article

1 Device and versions
2 Power supply for 12V LED strip: calculations and connection process
- 2.1 Calculations for the LED strip power supply
- 2.2 The process of connecting the LED strip to the power supply
3 The cost of products from trusted manufacturers
4 Self-made device
5 Additional recommendations
6 Summarizing
7 Video: connecting the power supply to the LED strip

Device and versions

Backlight from LEDs cannot be connected directly to a regular electrical network, as this voltage is too high for it. For its operation, an intermediate device is required that allows transforming electricity.

Places of connection of the main wires

To lower the voltage to the desired values, you must use a power supply for a 12V LED strip. You can buy it inexpensively in a specialized store.

Note! There are also adapters and tapes designed for higher voltages. It is usually 24V. However, such products are used at home much less often.

This is how a 12V SMD tape looks like

The adapter usually includes the following elements:

a step-down transformer;
Voltage regulator;
smoothing filter;
rectifier.

The simplest embodiment is a perforated metal converter. However, the disadvantages of such products are their relatively large size, lack of protection against dust and moisture, and low aesthetic characteristics.

Dirt and moisture particles can enter the perforations of open-type appliances

Another manufacturing option involves sealing the main microcircuit with a plastic case. The main advantages can be considered lightness and compactness. Of the negative factors, it is worth noting the low resistance to mechanical stress.

You can visually assess the compactness of the product in a plastic box

Devices in a sealed aluminum case are more expensive. They can be operated in rather harsh conditions, as they are resistant to moisture, dirt and mechanical influences. The power of products usually exceeds 100 watts.

Product example in a 250 W aluminum case

Note! For tapes up to 5 meters long, low-power network adapters can be used, which are plugged into a regular outlet. Their power usually does not exceed 60 watts.

Power supply for 12V LED strip: calculations and connection process

Independent work on connecting the device provides an opportunity to save money. However, it is required not only to study the sequence of actions, but also to familiarize yourself with the preliminary calculations that will allow you to choose the right device.

Calculations for a three-meter tape are clearly presented

Calculations for the LED strip power supply

Before calculating the power supply for the LED strip, you need to know the total power of the entire backlight. To determine how many watts one meter of flexible board consumes, you can use a special table.

A type	Number of diodes per meter	Power in kilowatts
SMD 5050	120	0,025
	60	0,014
	30	0,0072
SMD 3528	60	0,0048
	120	0,0072
	240	0,016

Main types of SMD LED strips

Thus, if in the process of work it is supposed to use SMD 3528 products with the number of 120 diodes per linear meter and a length of 6 m, then the calculations can be expressed as follows:

7.2 * 6 = 43.2 watts.

However, for stable operation, 30 to 50 percent of the power should be added to the result obtained:

43.2 + 30% = 56.16 W.

Answer: For the aforementioned backlight, an adapter with a power of at least 60W is suitable.

The process of connecting the LED strip to the power supply

In fact, connecting a power supply for a 12V LED strip is not too difficult. Each terminal has special markings next to it to ensure correct wiring.

Connecting the adapter to the flex board

The connection to the 220V network is made through terminals that have the letters: N - zero and L - phase. Grounding is carried out using the clamps marked with the symbol G. If there is no one in the house, then the terminal is not touched. The exit points contain the following letters: + V and –V.

Diagram of connecting tape and wires of the electrical network

Useful advice! After connecting the adapter to the main network and backlight, high-quality isolation of the contacts is performed. It is better to use not insulating tape, but a piece cable duct suitable size.

The cost of products from trusted manufacturers

The average price of a power supply unit for a 12V LED strip may vary depending on the manufacturer and technical parameters. The cost can also be influenced by the version. The table below will allow you to familiarize yourself with the prices of proven manufacturers from Germany and Taiwan for open-type products.

Manufacturer	Power in watts	Price in rubles
Gauss (Germany)	60	910
	100	1300
	250	2100
Mean Well (Taiwan)	75	1365
	100	1515
	150	2050

Self-made device

In fact, there are many power supply circuits for 12v LED strips, but the main problem lies in the selection of a transformer of the required power and the manufacture of a rectifier.

If you remove the body of the finished product, you can see the following

In this regard, it is proposed to build a device without a transformer with a quenching capacitor. Such power supplies have been used for quite a long time in small-sized lamps, motion sensors and burglar alarms. The assembly will use:

capacitor;
filtering capacitor;
diode bridge;
Zener diode;
resistors;
capacitor shunt;
circuit breakers.

A basic assembly scheme will allow you to arrange the elements in the desired order

In the presented circuit, the reactance of the capacitor acting as a ballast allows to extinguish the voltage without significant heat release. For safety, this element is shunted with a high-voltage resistor. The diode bridge acts as a filter that powers the LED chain. The zener diode protects the backlight from increasing direct current.

Additional recommendations

When connecting LED lighting, follow the guidelines listed below:

it is advisable not to connect in series tapes longer than 5 m in order to avoid loss of brightness in the final segment;
before cutting the flexible board into pieces, it is necessary to connect it in its entire state to the adapter for several hours for testing;
power supplies must not only correspond to the full load, but also have a power reserve of 20-30 percent on average;
when placing the tape on conductive surfaces, it is required to lay an insulating material;
it is better to connect the backlight to the power supply and connect the segments, and after that, fix it;
when fastening the tape, there should be no sharp bends, as this can lead to damage to the tracks that conduct electric current;
when fixing flexible elements, remove the protective film from the adhesive layer, and then stick to the surface in the right place.

The segments in this case are connected using RGB amplifiers

Summarizing

It is impossible to do without a 12V power supply for the LED strip when connected to the electrical network of a residential building. This device will have to be purchased from a store or assembled yourself from suitable parts. The main task is to reduce the voltage to the required values.