Power supplies can be used not only to connect LCD monitors, laptops and lamps. These devices can also be used. Typically, LED lighting is used for decorative lighting.
What is LED strip? This is a flexible board with LEDs and resistors placed on it. It does not impose any special requirements and its length can be changed using simple scissors.
12V power supplies provide strip LEDs with the electrical energy required for the required parameters. They stabilize voltage and protect against interference and burnout. When used outdoors, the glow elements are mounted in sealed housings.
Some advantages:
Blocks rated at 24V are used to connect SMD5050 LEDs with a calculation of 120 pieces per 1 meter.
Switching power supply units are a small device with a housing of 180x96x38 mm.
Specifications:
This is one of the most common types. The size of some models differs from each other.
Here are some examples:
Other differences in some species:
Safety and compliance with standards is guaranteed by the manufacturer. Therefore, before purchasing, familiarize yourself with the characteristics of the equipment.
To make installation of the block easier, it is equipped with a special connecting block with holes. In addition, the blocks do not allow the wire to involuntarily be pulled out and disconnected from the block with screw terminals, thanks to which the wire is connected.
Power supplies are cooled due to natural air convection. Some of them are made with built-in fans, similar to computer coolers, which prevent the device from overheating during long-term use.
These fans allow you to increase power. The only negative is the noise, which only increases over time. If you use this type of device, be sure to clean it regularly, lubricate the rotating mechanism, and remove dust from it.
The power supply or adapter is designed to connect equipment to power sources for its normal operation. The power supply for the LED strip serves as a converter of the input voltage to the required output voltage. In this case, we are talking about twelve volts.
The use of such a power supply requires certain competence. If the device is used for its intended purpose, it will not pose a threat to the health of the owner or the equipment.
Pulse adapters level out voltage surges using a special filter. Therefore, an electrical network with unstable voltage critically needs such a device. Voltage surges can not only negatively affect the operation of electrical equipment, but also damage it.
Designations in the photo:
12-volt units come in two main types:
In addition to these differences, the following types are available:
Since each model differs from each other in properties, characteristics and purpose, you should carefully approach the choice of device.
The power supply unit for LED strips is selected according to the following principles:
Be sure to pay attention to the power consumption of the adapter. When calculating the data, add 25 percent to the available belt capacity. Thus, the power supply will not operate under heavy loads. This is important to do to extend durability and trouble-free operation.
Example: 1 meter of LED strip with a power of 15 watts requires a connection of 5 meters.
We carry out the following operations:
Calculation of power supply for LED strip:
The average price for a 12V power adapter is 500-1000 rubles. Many older men who were once closely associated with technology take their devices to the flea market. You can buy an inexpensive, time-tested adapter from them.
To make your own power supply you will need:
What we may need to assemble the LED strip power supply:
We present to your attention the assembly diagram for a 12V power supply:
Designations:
Step by step guide:
Connection diagram of the power supply to the LED strip. To connect the power supply to the LED strip, we need a cord with a plug. It is important to install a switch on the cord.
We take the adapter and find 4 contacts:
Attention! If you try to connect the tape directly to an outlet, it will start to smoke and, naturally, will not work after that.
Supplying a circuit of LEDs with electricity is no different from any other similar circuit of several DC consumers that are powered by a rectifier from a household AC network. This article will consider both ready-made switching power supplies (UPS) and circuit diagrams of several home-made units for.
The most commonly used sets of LEDs with a voltage of 12 Volts. This is due to the short length of the purchased tapes and the prevalence of devices that output this voltage. A larger length - from about 5 meters - will require more voltage passing through thin copper conductors connecting the diodes.
Depending on the type of room where the lighting will be used, the type of power supply is selected. Purely visually, they can be divided into perforated metal ones, similar to a laptop power supply, and embossed metal ones without visible holes.
Functionally, these current sources can be equipped with brightness regulators or a control panel. In hardware stores, UPS can be found under the names “switching rectifier” or “LED lighting driver.” Each switching power supply model has its own level of protection from external influences.
The security level code is located in the documentation or engraved on the case. It consists of the abbreviation IP and a couple of numbers. The first number indicates the degree of protection against solid foreign objects - impact resistance, and the second - the moisture resistance class.
There are three main criteria for selecting a suitable UPS for tapes - the tightness of the unit, the peak power of the consumer and the output voltage.
Among UPSs for LED strips, the following protection classes are most common:
Peak output power is calculated based on total power all LEDs in the strip at their maximum brightness. Sometimes the manufacturer specifies how much power should be used per meter of tape. But if there is no such characteristic, you can find out the power of one meter by multiplying the maximum power of one LED by their number.
A 20% margin is usually added to the resulting value. The approximate power of one meter of LED 12-volt LED backlight is 60 watts. In order to provide a degree of illumination equal to a conventional incandescent base lamp, you need to use a 10-watt strip.
Additionally, you should take care of cooling the power supply by choosing a well-ventilated place away from radiators and other heat sources. In addition to cooling grilles, a switching power supply with a metal case can be equipped with a fan for an active cooling system. The operating range of the UPS ranges from -25 to +40 degrees for devices with medium and low protection classes.
In addition to cooling grilles, a switching power supply with a metal case can be equipped with a fan for an active cooling system Simple unprotected models with passive cooling for the spring of 2017 have an estimated cost of 10-20 rubles per 1 W of power. More expensive models with a sealed housing and cooling system have a cost in the range of 40 rubles per 1 W.
Price for 12 V power supplies for strips of LEDs start at 100 rubles for models with a power of 18-20 W on Aliexpress and similar online sites. In retail stores, the markup can reach up to 50-80 rubles per 1 W for the most primitive UPS.
It is also worth considering the fact that the manufacturer often significantly overestimates the characteristics of its device. The easiest way to distinguish a powerful device visually is that it will have large cooling radiators and large-gauge wires.
More expensive models with a sealed case and cooling system have a cost in the range of 40 rubles per 1 W Of course, it is possible to independently manufacture this current source based on amateur radio circuits. First, you should understand a little about the principle of operation and design elements of power supplies from a 220 V household network.
It is highly not recommended to use an archaic transformer power supply directly due to strong heating and incompatibility of current-voltage characteristics (volt-ampere characteristics) of LED technology. The current-voltage characteristic of lighting LEDs is not directly proportional; the current consumption here does not grow in a straight line, but exponentially.
When connecting the tape to power supplies from a laptop or tablet that are suitable in terms of power, you should use additional voltage stabilizers that lower it from 19 Volts to 12 based on the LM2596 unit. Such a device has a high efficiency, reaching 90%, and a low cost - up to 50 rubles per piece with delivery in the online store.
Find it in the catalog simply by entering the name. The lack of power can be compensated for by cutting a long strip into several equal parts and making several such blocks, then connecting them in parallel and connecting them to the network. LM2596 can be used to power the strip from a car's cigarette lighter by connecting it through a 5A fuse.
To manufacture a switching power supply completely from scratch, it will be necessary to first assemble a simple 220-volt AC rectifier, and then expand the structure with several stages of switching rectifiers and a pulse-width modulation module, if desired, providing an additional cooling system. The bulk of the parts can be obtained from used uninterruptible power supplies and computer power supplies.
The first option for a 12 V current source for the tape is a modified power supply from a computer based on the IR2151 half-bridge driver. The unit is small in size and can be placed in the case of the computer unit itself with minimal modifications.
Diagram of a transformerless power supply with a ballast capacitor The transformer will need to be opened and rewinded. The primary winding is wound with copper wire with a diameter of 0.8 mm and consists of 40 turns. The secondary requires 2x3 turns of a bundle of 7 wire strands of the same diameter. Behind the secondary winding is a paired 2x30 Ampere Schottky diode, screwed to the housing for cooling.
Almost all capacitors of the required capacities can be found on the board of a computer power supply. Manipulations with increasing or decreasing their capacity directly affect the power of the power supply.
To power the main microcircuit, you need a very powerful limiting resistor, rated at 2 W; its heating during operation contributes to fluctuations in the nominal resistance by one tenth of the total value, but this will not affect the brightness of the lighting.
Field-effect transistors are protected from voltage surges by an additional thermistor. The diode bridge is built from 4 1N5408 diodes, designed for a voltage of 1 kV and a current of 3A. This power supply is extremely powerful and is designed for a large load of several hundred watts.
The disadvantage of the design is the lack of a dimmer to regulate the brightness of the glow and a built-in fan of the cooling system, which must be connected to a separate power supply to avoid flickering of the tape.
The resulting UPS can and should be equipped with additional functionality. Due to the low voltage used, a classic dimmer operating on the principle of changing the output voltage is not suitable for the design. Instead, we will consider a dimmer circuit for smoothly adjusting the brightness (for monochrome) and color (color) of PWM-based tapes.
There is a ready-made regulator board suitable for the characteristics with high current and low voltage NM4511 for sale, costing 300 rubles from the specialized company MasterKit. However, self-assembly will not require much difficulty and skill. The circuit is based on a dual operational amplifier LM358 and a powerful transistor IRF3205.
Finally, I would like to talk about cooling the assembled structure, which will pass a high amperage current. As mentioned above, to eliminate the flickering effect, the fan should be powered from a separate current source.
In the considered circuit, it is possible to connect it in parallel with the main line of the primary circuit of the power supply. It is better to provide the transformer itself with a separate radiator, pressing it to the core with thermal paste and bolting it to the main board.
To increase the heat exchange area, you can replace one of the housing covers with a large radiator, which can be found in old Soviet amplifiers and voltage rectifiers. A good solution would be to use computer power supply models that use a large diameter fan, as they produce less noise.
Content
LED strip is a lighting device designed for decorative lighting in the home, cafe, and on billboards. The LED device is made of plastic onto which LEDs are attached. The voltage of the power supplies for the LED strip is 12V or 24V. Sometimes a transformer designed for a computer is used. The power supply is produced with built-in automatic protection, which protects against network overload and short circuit.
The source that allows you to adjust the mains voltage for LED backlighting is divided into several types:
Power supplies for LED strip are transformer and pulsed:
If you choose the wrong transformer for a design with LEDs, this can lead to damage to the lighting equipment and even cause a fire. You can often find controllers that produce stable voltage readings that cannot be changed. This does not affect the brightness parameters of the LEDs, but, on the contrary, makes the conductor’s work easier. The mini-transformer must be configured to match the performance of the selected LED strip to avoid voltage problems.
It is very important to purchase or make your own a conductor that will match all the conditions of a certain circuit and be used correctly. How to choose a power supply for LED strip? To make the right choice you need to calculate:
When calculating power, it is necessary to take into account the length of the LED device. To select a device with the required performance, you need information about the consumption of one meter of tape. Let's look at an example of how to calculate the power of a power supply. You have chosen a light source of type SMD 5050 with 30 diodes, its length is 5 m. Calculation:
Connecting the unit is simple. If decorative lighting will be installed during the construction of the building, then it is better to bring the electrical wiring as close as possible to the place where the tape will be placed. Install an outlet there. When this is not possible, it is worth purchasing a cable of the required length in advance. The power supply must be equipped with a plug that will connect to the network (if this is not available, then it must be made by hand).
Connection steps:
Anyone can make their own conductor, which will be useful for operating the device with LEDs. To construct a 20-link power supply you will need:
Anyone can connect the power supply. The main thing is to strictly follow the instructions. Thanks to the video, you will understand how to properly power the lighting equipment, what actions are performed for the correct and safe operation of the lighting. The video shows in detail the process of connecting the block for the LED strip. Video instructions will clearly explain the features of each stage of work.
Found an error in the text? Select it, press Ctrl + Enter and we will fix everything!Diodes are the simplest modern way to organize cheap lighting. We suggest you consider how to make and connect a power supply for an LED strip with your own hands, as well as power calculations and device selection.
LED strips are an excellent alternative to powerful lighting, for example, from an incandescent lamp or an energy-saving lamp. Selecting LEDs is not difficult; the biggest problem is connecting them to the network. In order to organize convenient and beautiful LED lighting, you will need a special power supply.
Photo – Power supply for LED stripThe power supply, also known as a small transformer or conductor, is one of the most important components of an LED system and is designed to power the LEDs. Its dimensions are small, so you can easily mount the device under a false ceiling or in furniture. Using the wrong type of power supply device can not only damage the LED strip, but also cause a fire in your home. It is also important to know what AC input voltage you need and to be sure that the selected device meets these parameters. For the construction of the housing, plastic is mainly used, which resists many external destructive factors (it can be used outdoors, in damp rooms). Let's look at how to choose the right power supply:
The constant voltage that LED products require before operation is key when choosing a transformer model and its power level. Most stores offer a non-adjustable controller, i.e. it always outputs the same voltage. This does not mean that the brightness of the lamps will not be controlled; on the contrary, this indicator is controlled by a special PWM dimmer, which greatly simplifies the operation of the power supply. The most popular models with a built-in dimmer are Feron (for RGB strip LB005 30W 12V), Led Lamp, 450W GEMBIRD ATX (120mm fan) CCC-PSU, Arlight, ARPV LV-35-12, NS-LV-50-12 (12V, 4A, 50W), HTS-100, YGY-121000, ZC-BSPS 12V3,3A=40W jaZZway.
Once you have determined the voltage of the LED product you want to use, you need to calculate the distance of the entire LED strip.
The power selection for any LED strip power supply is made according to a special table; we recommend that you read the instructions of the selected company. It is very important not to skimp on a device with the required power.
Before installing a low-power or multi-channel transformer, you need to calculate some parameters. If you know the length of the LED strip and the power, then you need to multiply these indicators and add 10-5 percent error to them. The resulting number will be an indicator of the heat flow W/m2, and depending on it you need to select a power supply. This will help protect yourself and your family from short circuits and cable burnouts.
Now all that remains is to assemble the power supply and tape into one working system. If you do not use a computer transformer, then you need:
Take a small piece of wire and a short green and black wire. This is how we will mark the phase and ground cables. Connect the electricity to the yellow and black wires. Let's say Yellow = 12 + Red = 5V + Black = Ground. To ensure a clean installation, you may need to completely disassemble the transformer. Cut out all the wires, leaving a couple of black cords, a green cable and some yellow ones.
Photo - Connecting the power supply Remove the green and black cords, twist them together and set them aside. Check that the black and yellow wires are connected correctly, and then connect the device to the network. Make sure that the device is sealed, the output cable is well sealed, and other contact points are not touching.
Photo – Compact power supply for LED strip After finishing work, put the housing back in place, turn on the voltage, and check the correct LED lighting sequence. As you can see, connecting a transformer with your own hands is a fairly simple task.
Video: connecting LED strip to power supplies
Making your own power supply for LEDs is quite simple. For a 20-cell tape you will need:
We connect all the devices according to the standard scheme and connect a homemade conductor to the tape. The unit can be assembled in an old housing from a regular mini-transformer, and the wire is hidden in it. For convenience, below is a diagram of the power supply circuit for the LED strip:
Photo – Power supply circuit diagram for LED strip 
Photo – Diagram of an LED strip with a block 
Photo - Connecting the LED strip to the network Not everyone can correctly connect all parts of the circuit, so it is often more profitable to purchase a ready-made transformer. You can buy a compact and sealed power supply at any electrical goods store.
The cost of devices may vary depending on the manufacturer (China will be cheaper), or additional functionality (with remote control, motion sensors, etc.). If necessary, it is quite possible to independently modify the device to suit your taste and needs.
LEDs are replacing types of light sources such as fluorescent and incandescent lamps. Almost every home already has LED lamps; they consume much less than their two predecessors (up to 10 times less than incandescent lamps and 2 to 5 times less than CFLs or energy-saving fluorescent lamps). In situations where a long light source is needed, or it is necessary to organize illumination of a complex shape, it is used.
LED strip is ideal for a number of situations; its main advantage over individual LEDs and LED matrices is power supplies. They are easier to find for sale in almost any electrical goods store, unlike drivers for high-power LEDs, and besides, the selection of a power supply is carried out only by power consumption, because The vast majority of LED strips have a supply voltage of 12 Volts.
While for high-power LEDs and modules, when choosing a power source, you need to look for a current source with the required power and rated current, i.e. take into account 2 parameters, which complicates the selection.
This article discusses typical power supply circuits and their components, as well as tips for repairing them for novice radio amateurs and electricians.
Types and requirements for power supplies for LED strips and 12 V LED lamps
The main requirement for a power source for both LEDs and LED strips is high-quality voltage/current stabilization, regardless of mains voltage surges, as well as low output ripple.
Based on the type of design, power supplies for LED products are divided into:
Sealed. They are more difficult to repair; the body cannot always be carefully disassembled, and the inside may even be filled with sealant or compound.
Non-hermetic, for indoor use. Better amenable to repair, because... The board is removed after unscrewing several screws.
By cooling type:
Passive air. The power supply is cooled due to natural air convection through the perforations of its case. Disadvantage is the inability to achieve high power while maintaining weight and size indicators;
Active air. The power supply is cooled using a cooler (a small fan, as installed on PC system units). This type of cooling allows you to achieve more power in the same size with a passive power supply.
Power supply circuits for LED strips
It is worth understanding that in electronics there is no such thing as a “power supply for an LED strip”; in principle, any power supply with a suitable voltage and a current greater than that consumed by the device will be suitable for any device. This means that the information described below applies to almost any power supply.
However, in everyday life it is easier to talk about a power supply according to its purpose for a specific device.
General structure of a switching power supply
Switching power supplies (UPS) have been used to power LED strips and other equipment for the last decades. They differ from transformer ones in that they operate not at the frequency of the supply voltage (50 Hz), but at high frequencies (tens and hundreds of kilohertz).
Therefore, for its operation, a high-frequency generator is needed; in cheap power supplies designed for low currents (units of amperes), a self-oscillator circuit is often found; it is used in:
electronic transformers;
electronic ballasts for fluorescent lamps;
mobile phone chargers;
cheap UPS for LED strips (10-20 W) and other devices.
A diagram of such a power supply can be seen in the figure (click on the picture to enlarge):
Its structure is as follows:
The OS includes an optocoupler U1, with its help the power part of the oscillator receives a signal from the output and maintains a stable output voltage. There may be no voltage in the output part due to a break in the VD8 diode, often this is a Schottky assembly and must be replaced. A swollen electrolytic capacitor C10 also often causes problems.
As you can see, everything works with a much smaller number of elements, the reliability is appropriate...
More expensive power supplies
The circuits that you will see below are often found in power supplies for LED strips, DVD players, radio tape recorders and other low-power devices (tens of watts).
Before moving on to considering popular circuits, familiarize yourself with the structure of a switching power supply with a PWM controller.
The upper part of the circuit is responsible for filtering, rectifying and smoothing ripples of the mains voltage 220, essentially similar to both the previous type and the subsequent ones.
The most interesting thing is the PWM block, the heart of any decent power supply. A PWM controller is a device that controls the duty cycle of an output signal based on a user-defined setpoint or current or voltage feedback. PWM can control both load power using a field (bipolar, IGBT) switch, and a semiconductor controlled switch as part of a converter with a transformer or inductor.
By changing the width of the pulses at a given frequency, you also change the effective value of the voltage, while maintaining the amplitude, you can integrate it using C- and LC-circuits to eliminate ripple. This method is called Pulse Width Modeling, that is, modeling a signal using the pulse width (duty factor/duty factor) at a constant frequency.
In English it sounds like a PWM-controller, or Pulse-Width Modulation controller.
The figure shows bipolar PWM. Rectangular signals are control signals on transistors from the controller; the dotted line shows the shape of the voltage in the load of these switches - the effective voltage.
Higher-quality low-average power supplies are often built on integrated PWM controllers with a built-in power switch. Advantages over self-oscillator circuit:
The operating frequency of the converter does not depend on either the load or the supply voltage;
Better stabilization of output parameters;
Possibility of simpler and more reliable adjustment of the operating frequency at the stage of design and modernization of the unit.
Below are several typical power supply circuits (click on the picture to enlarge):
Here RM6203 is both a controller and a key in one housing.
The same thing, but on a different chip.
Feedback is carried out using a resistor, sometimes an optocoupler connected to an input called Sense (sensor) or Feedback (feedback). Repair of such power supplies is generally similar. If all the elements are working properly, and the supply voltage is supplied to the microcircuit (Vdd or Vcc leg), then the problem is most likely in it, more accurately looking at the output signals (drain, gate leg).
Almost always, you can replace such a controller with any analogue with a similar structure; to do this, you need to check the datasheet against the one installed on the board and the one you have and solder it, observing the pinout, as shown in the following photographs.
Or here is a schematic representation of the replacement of such microcircuits.
Powerful and expensive power supplies
Power supplies for LED strips, as well as some power supplies for laptops, are made on the UC3842 PWM controller.
The scheme is more complex and reliable. The main power component is transistor Q2 and transformer. During repairs, you need to check the filtering electrolytic capacitors, the power switch, Schottky diodes in the output circuits and output LC filters, the supply voltage of the microcircuit, otherwise the diagnostic methods are similar.
However, more detailed and accurate diagnostics are only possible using an oscilloscope; otherwise, checking for short circuits on the board, soldering of elements and breaks will cost more. Replacing suspicious nodes with known working ones can help.
More advanced models of power supplies for LED strips are made on the almost legendary TL494 chip (any letters with the numbers “494”) or its analogue KA7500. By the way, most AT and ATX computer power supplies are built on these same controllers.
Here is a typical power supply diagram for this PWM controller (click on the diagram):
Such power supplies are highly reliable and stable.
Brief verification algorithm:
1. We power the microcircuit according to the pinout from an external power source of 12-15 volts (12 leg is plus, and 7 leg is minus).
2. A voltage of 5 Volts should appear on the 14 legs, which will remain stable when the power supply changes; if it “floats” - the microcircuit needs to be replaced.
3. There should be a sawtooth voltage at pin 5; you can “see” it only with the help of an oscilloscope. If it is not there or the shape is distorted, we check compliance with the nominal values of the timing RC circuit, which is connected to pins 5 and 6; if not, in the diagram these are R39 and C35, they must be replaced; if nothing has changed after that, the microcircuit has failed.
4. There should be rectangular pulses at outputs 8 and 11, but they may not exist due to the specific feedback implementation circuit (pins 1-2 and 15-16). If you turn off and connect 220 V, they will appear there for a while and the unit will go into protection again - this is a sign of a working microcircuit.
5. You can check the PWM by short-circuiting the 4th and 7th legs, the pulse width will increase, and short-circuiting the 4th to 14th legs, the pulses will disappear. If you get different results, the problem is in MS.
This is the most brief test of this PWM controller; there is a whole book about repairing power supplies based on them, “Switching Power Supplies for IBM PC.”
Although it is dedicated to computer power supplies, there is a lot of useful information for any radio amateur.
Conclusion
The circuitry of power supplies for LED strips is similar to any power supplies with similar characteristics; they can be repaired, modernized, and adjusted to the required voltages quite well, of course, within reasonable limits.
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