Modern electronics are often equipped with external power supplies for 5V, 12V, 19V. After an appliance breaks down, they often end up lying around in a closet or nightstand.
- 5V is the voltage of phone and USB chargers;
- 12V - used in computers, some tablets, TVs, network routers.
- 19V - in laptops, monitors, monoblocks.
We will consider how any . There will be only simple and budget options available to everyone. 5V chargers are not suitable. But I use these chargers to make night lights; 3 or 6 diodes are glued to the body. At night the light is not bright, but just right.
- 1. 12V power supplies
- 2. 19V power supply
- 3. Characteristics of switching stabilizers
- 4. Simple DIY circuits
- 5. Video on how to modify it yourself
- 6. Ready-made modules from China
- 7. Power and driver in one module
- 8. Where to buy cheap?
12V power supplies
12V power supplies from electronics typically range from 6 to 36 watts. 10 watts is enough to illuminate the work surface. Such blocks are divided into 2 main types:
- old ones on transformers are heavy;
- modern pulse ones, also called electronic transformers, are distinguished by their low weight and high power with small dimensions.
I do not recommend using it on transformers. When I first connected the transformer power supply from the router, the power of which was 2 times the power of the tape. The rectifier itself began to get very hot. I installed the diode bridge of the rectifier on a homemade radiator for cooling, it still gets very hot, it won’t last long. There was no time to understand the intricacies, so I asked a specialist. He somehow found the reason: LEDs have a special current-voltage characteristic (abbreviated as VAC), which leads to strong heating. He gave me a 12V and 2 Ampere TV, that is, the power is 24W. Now everything works without problems and does not heat up.
19V power supply
Notebook type power supply 19V, 90W
A voltage of 19V is widely used in desktop computer equipment, most often in laptops, monoblocks, monitors, and scanners. This category includes power supplies from printers; they are powerful, available in 16V, 20V, 24V, 32V.
I’ve had an excellent 90W and 19V from an Asus laptop lying around for a long time. This power is enough to power a 6000-lumen LED strip, and this is enough to provide diode lighting for a 20-square-meter room. But the power supply is not 12 volts, and will require modification. We won’t go inside the case; re-soldering a circuit for 12 volts is difficult, time-consuming, and you have to be an electronics engineer. Let's make it simpler, connect a small step-down regulator with a stabilizer. There are two types.
Type No. 1
Stabilizer for 7812
The stabilizer on a chip like KREN 7812 (), looks almost like a transistor, and when installed on a cooling radiator, can withstand a current of 1 Ampere. This option is outdated and cumbersome. To use the full power of a laptop PSU, you will need 5-6 of these (or 1 large one) and a large aluminum radiator for cooling.
Type No. 2
A modern pulse stabilizer, miniature, does not heat up, and is as simple as 3 rubles. In Russian stores they ask for 600-900 rubles, the price is greatly inflated. The Chinese sell 3 amps for 50 rubles, 5-7A sells for 100-150 rubles, so I recommend ordering a couple of pieces on Aliexpress.
I recommend using a pulsed one, its efficiency is higher than 80-90%, it’s simpler and cheaper. Just don't buy a current source for the LM2596, you need a voltage source. To find in a Chinese online store, use the following queries:
- LM2596 power supply;
- 12v switching regulator;
- voltage regulator 12v 7a;
Characteristics of switching stabilizers
In video instructions, a specialist will tell you the main technical characteristics of modern switching stabilizers, circuit design and recommendations for their correct use. So that you don't burn it with your own hands during experiments.
Simple DIY diagrams
If the power supplies described above are not suitable for you, then the power supply for the 12V LED strip can be soldered according to the circuit yourself. A homemade one will require a lot of time and a lot of details; I will not consider complete diagrams for connecting to a 220B network. With the modern development of electronics, it is easier to buy them from the Chinese. There are diagrams for DIY assembly using the TL594 and other new elements. But I like the one described below better; it can be easily repeated in 10 minutes.
Let's consider the optimal and modern one on LM2596. You will need to install only 4 radio elements. Analogs with similar functionality are ST1S10, L5973D, ST1S14.
There are several modifications of the microcircuit:
- fixed 12 V, LM2596-12, indicated at the end of the marking;
- adjustable version LM2596ADJ;
- the price in Russia for one is 170 rubles. In China, the entire assembled unit on LM2596 costs 35 rubles. including delivery.
Characteristics
Video on how to modify it yourself
A colleague will similarly tell you how to connect and configure a stabilizer to a 19V power supply from a laptop.
Ready-made modules from China
Option with output regulator from 3 to 37V
In the first circuit we will use LM2596ADJ with adjustable output voltage. It can be produced in different cases, but the most optimal one is like in the picture. The advantage of this design is the ability to adjust the brightness of the LED strip without a dimmer.
Circuit with fixed 12B
The stabilizer is based on the LM2596-12 chip, there is no variable resistor for adjustment, the output is exactly 12B. The circuit is simpler by one detail.
Power and driver in one module
Universal option, current and voltage are adjustable. You can power not only the diode strip, but also LEDs. that is, it can act as a driver and electronic transformer.
The video clip will show you how to use and configure yourself a universal version of the module with a driver and adjustable current.
Where to buy cheap?
It happens that you don’t have a suitable power supply at home for household appliances, but others definitely have one, it’s also lying around idle. First, ask your friends or neighbors, they probably have something. For a couple of hundred or liquid currency you can negotiate with them.
You will find a large assortment on Avito and on local forums. Many people get rid of unnecessary junk and sell power supplies for a symbolic price, because it’s a shame to throw them away, but they don’t know the real cost. Thus, I often buy good devices, especially since no one canceled the bargain. Recently I managed to buy a branded ACER from a 190W monoblock for 400 rubles. It is sealed and of high quality, since computer electronics require very stable and high-quality power, unlike diode strips.
LED lighting is widely used in everyday life. It is relevant for individual surfaces either as an additional or. In order for the lighting to be stable and the installed products to last as long as possible, you should choose the right 12 V power supply for the LED strip. A wise choice will avoid a premature decrease in the quality of the glow and will protect the product from changes.
Before choosing LED strips for interior design, you should familiarize yourself with the operating features of such products. For example, it is impossible to directly connect to 220 V, since they were originally designed for 12 V. Violation of this rule will lead to failure of the tape.
To prevent the lamps from burning out, it is necessary to reduce the voltage in the power source from 220 V to the required value. This can be realized using a 12 V power supply. For a 12 V LED strip, it is a necessary element, without which it is impossible to connect the product to.
Attention! The most widespread are 12 V LED strips, but 24 V models can be found on sale.
Advantages and disadvantages of 12 V power supplies
The power supply has a number of undeniable advantages:
- Increases electrical safety when operating LED strip;
- Increases the service life of the product;
- Reduce the consumed voltage to the required level;
- Allows you to stabilize the load on.
The disadvantages of such devices include the cost of purchasing them, as well as the need for decoration during installation work. We have to consider various options for positioning the power supply relative to the tape, allowing the device to be kept away from others.
Types of 12 V power supplies
Manufacturers offer ready-made devices with various design options. Depending on the level of protection against precipitation, devices can be:
- Sealed allowing operation in elevated conditions, including open air. Able to remove heat well and not afraid of unfavorable natural factors;
- Semi-hermetic. A universal option that can be used inside and outside the building. Has a degree of protection IP54;
- Leaky, which can be used in dry rooms.
A wide range of models allows you to select a power supply with a power consumption of 12-800 W, designed for a current of 1-66 A. There are products with active and passive cooling. In the first case, the device is equipped with a built-in fan, which, while providing the required level of heat dissipation, is capable of creating some noise during operation.
Power supplies for 12 volt LED strips can be in a sealed housing made of:
- Plastic. Such models are compact, airtight, light weight and compact in size. At the same time, they are characterized by poor heat transfer and limited power selection. Maximum power does not exceed 100 W;
- Aluminum. The most expensive type, characterized by a high level of reliability, tightness and strength. Due to its characteristics, it has good heat transfer and is not afraid of the effects of most negative factors: temperature fluctuations, direct sunlight, humidity. not only in everyday life, but also in installation;
- Other metals. The devices are manufactured with perforation and contact pads. They can be installed in dry rooms, highlighting closed areas to reduce the amount of dust that gets inside.
How to calculate the power supply for an LED strip with your own hands
In order for the power supply to work stably, it is necessary to correctly calculate its power in advance. The calculation will require knowledge of the rated voltage and power that one meter of LED strip Pm will consume. These indicators are individual and depend on the components included in the LED strip, their quantity per linear meter, as well as the length of the product itself (L).
- We find the total load by multiplying the power per linear meter of the LED strip by its length: Ptot = L × Pm . For example, if the power of a linear meter is 15 Watts, then five meters of tape will consume 5 × 15 = 75 Watts;
- We multiply the resulting value by the safety factor kz, which is numerically equal to 1.2…1.3: Pbp = kz × Ptot = 1.2 × 75 = 90 W. The safety factor will allow you to avoid overheating of the power supply during operation. We select a device with a power that is greater than the calculated value.
Attention! When calculating the power of the power supply, you should take into account the power of the RGB controller included in the connection diagram. This value, as a rule, does not exceed 5 W.
If the power of a linear meter of LED strip is unknown, you can calculate it yourself. To do this, you need to know exactly how many and what kind of LEDs are contained in one linear meter. Let it be 30 pieces of SMD 5050, each of which is designed for a current of 0.02 A. In this case, the total value of the current consumed will be equal to 30 × 0.02 A = 0.6 A. Hence the power per linear meter of the LED strip is 0, 6 Ax12 V = 7.2 W.
Connecting the power supply to the LED strip with your own hands
Before you figure out how to connect the power supply, we suggest you get acquainted with the symbol on the device and the LED strip:
| Photo | Description of work |
 | , intended for connecting the power supply to the network, are marked L and N. The order of connection (“+” / “–”) does not matter. You can connect the device to the power source in any order. |
 | If available, you can connect to the terminal marked accordingly. |
 | Terminals designed for connecting LED strip. Designated as +/– V, depending on polarity. When connecting, this requirement must be taken into account. |
| On an LED strip, the wire with positive polarity is usually red, and the wire with negative polarity is black. On the tape itself, the contact points are labeled as follows: positive - 12 V, negative GRND, or there may be no inscription at all. Some manufacturers use V+ / V- markings. |
Parallel connection
This scheme is relevant if the required lighting exceeds 5 meters. A serial connection is not possible, since the load on the current-carrying paths will exceed the permissible value and fail. Also during operation there will be an uneven glow. In this case, the products are connected in parallel:
| Photo | Description of work |
 | Each piece of tape is connected to a busbar with a suitable cross-sectional size (1.5 cm²). To connect the LED strip to the bus, you can use wires of a smaller cross-section (0.75 cm²). |
 | Not LED strips, but buses will be connected to the power source. |
 | After checking the correct connection, the wires should be connected to the appropriate terminals on the power source. |
Serial connection
If the length of the connected product is less than 5 meters, it is not necessary to resort to a parallel connection circuit. In this case, you can connect the power supply to the LED strip as follows:
- We connect the power cord to the corresponding terminals on the device. As a rule, blue and brown wires correspond to “phase” and “zero”, and yellow-green wires correspond to grounding. If there is no ground, this terminal remains unoccupied;
- We connect the tape to the appropriate circuits;
- We check the functionality of the system.
Attention! The absence of a ground wire violates the requirement for the safety level of the installed lighting system.
How to make a power supply for a 12 V LED strip with your own hands
It is not always possible to purchase a suitable 12 V power supply model. In this case, you can make the device yourself:
| Photo | Description of work |
| We prepare the necessary materials and tools:
|
 | Using a multimeter, check the polarity of the charger. |
 | Solder the DC-DC converter to the charger, observing the polarity. |
 | We connect the tape to the output contacts of the DC-DC converter, observing the polarity. |
 | We check the functionality of the created 12 V power supply. |
Attention! A homemade power supply for LEDs has current limitations. In the example given, 1 A. This value must not be exceeded.
Instead of a power supply from a phone, you can use a converter from a computer or other equipment. A transformer for a 12 volt LED strip may not be the best choice, since their parameters often exceed the required ones by two or more times. This will lead to the fact that during operation such a device will constantly overheat. Additional cooling will not solve the problem. That is why, if you have a choice, it is better to give preference to a switching power supply.
Repair of 12 V power supply
After some period of use, the lighting may stop working. The cause of failure may not always be the burnout of the LED strip: the power supply may fail. There are many reasons that can cause the converter to fail:
- Prolonged exposure to high humidity conditions, if the device was not originally designed for such operating conditions;
- Accumulation of dust and dirt inside the device;
- Poor assembly of the device or the use of low-quality parts when assembling the product;
- Violation of operating conditions due to non-compliance with the manufacturer’s requirements;
- Initially incorrect calculation of indicators. Often, after preliminary calculations of the power value, some users do not add 20-30% to the required value, and therefore the unit operates at the limit of its capabilities.
Attention! Before starting repair work, you should accurately determine the cause of the power supply failure.
The following signs indicate that the device is burnt out:
- A characteristic burnt smell that intensifies after opening the case;
- Presence of blackened, swollen or burnt parts. Most often, capacitors swell;
- There is a break in the tracks and contacts between the elements of the electrical circuit.
Attention! If you find a hole in a burnt-out board or significant damage to individual parts, refuse repairs: it will not be cost-effective.
If there are several damaged parts for the device, it will be enough to replace them. To do this, you will need a circuit diagram for the operation of the converter, although most often such devices have a standard circuit, and the cause of failure may be the burnout of transistors, capacitors, or a dual diode. The remaining parts rarely burn out.
Problems can be diagnosed in the following sequence:
- Having opened the case, we check the functionality of the fuse. If it works, we control the voltage on the capacitors (C22, C23). They must be energized at this time. Its performance is indicated by a value of about 310 V;
- We carry out PWM diagnostics;
- We control the output voltage and check the performance of the microcircuit using an oscilloscope.
Article
To connect consumers of electrical energy in Russia, current standards provide for an alternating current network of 220/380V 50Hz. Since LED strips are powered from a pulsed stabilized source with a voltage of 24 or 12V, a device is needed that converts high alternating voltage to a lower one.
Successfully copes with this task power supply for LED strip (PSU) . The stability and duration of the backlight is ensured by a competent choice of power supply.
Any of the commercially available models allows operation of the backlight over a wide temperature range, smoothes out impulse noise well, and has a housing that protects internal elements from mechanical damage.
LED strip power supply circuit - power supply circuit
Connecting power to an LED strip with your own hands is not that difficult. The main thing is to strictly follow the advice outlined below.
Before purchasing one or another rectifier model, you need to understand the question of how to connect the LED strip to the power supply.
LED strips can be connected to a power source in various ways. If the power supply circuit for LED strips is strictly followed, even one powerful device can provide operation of both one and several backlights.
For the uninterrupted operation of a circuit using one power supply, it is important to comply with the condition - the power of the unit must be at least 30% greater than the total load.
To connect a second LED strip in parallel to one unit you will need additional extension cord- a wire with a cross-section of at least 1.5 mm. Observing the polarity, one end of it is connected to the output of the power supply, the second to strip No. 2. In this case, the current will be supplied not through the tracks of the first backlight, but through the connected wire.
When the use of a large, powerful power supply is unacceptable, low-power power supplies for 12-volt LED strips are used. The connection diagram provides for the presence separate power supply for each strip of diodes. Here you will also need extension- a wire connected to a 220 V network and to a specific tape, but its cross-section may be smaller - 0.75 mm is enough. Although in this case the installation is more complex, a similar connection diagram is often used in practice, since it involves the use of small-sized power supplies.
Where to hide the LED strip power supply?
The location for the power supply is selected taking into account:
- connection diagram used;
- number of rectifier devices;
- block dimensions.
A large, powerful power supply for an LED strip in an apartment is difficult to make invisible - it is necessary to equip a special niche.
Suitable options for placing a large power supply may be a specially made hole in the furniture or a separate shelf on the wall, equipped on the non-visible side of the table.
In case of small-sized power supplies(no more than 250x150x100 mm) everything is much simpler:
- can be hidden under the ceiling trim;
- cut a special place in the plasterboard wall;
- install the power supply in a wall niche.
Power supply for LED strip - types and features
Unsealed or open 100 W units are used to power consumers in closed residential and non-residential premises. Devices of this type are easy to identify: as a rule, they differ largest size and weight, are appropriately marked IP20.
The walls of the housing are perforated to ensure heat dissipation and are made of plastic or sheet metal. Scope of application: equipment power supply. Placement: special cabinets or hardware niches.
It should be remembered that unsealed devices are not protected from moisture, so they are not recommended for use in rooms with high humidity, for example, in bathrooms.
Semi-hermetic (all-weather) power supplies can be classified as a universal device. The devices are used both indoors and outdoors. The unit is used to power a 12V LED strip, has a degree of protection IP54 and a sheet metal housing.
The best solution today is sealed power supply for LED strip with plastic housing . The power of the device does not exceed 75 W, it is completely protected from moisture, and has small dimensions and weight. Even using two 50 W power supplies of this type to power two LED strips, they can be easily hidden from human eyes in any corner of the room. Place of application: interior lighting.
How to calculate the power of a power supply?
The power of the power supply for the LED strip depends on the load connected to it. If for small consumers a 40 W power supply is sufficient, then for more substantial designs you may need a device whose power reaches 0.5 kW.
To correctly calculate the power of a power supply, you need to know:
- number of LEDs used for illumination;
- the load (power consumption) created by 1 meter of LED strip is taken from the table;
- total length of the tape (standard size - from 1 to 5 m);
- safety factor kз = 1.2.
1. Determining the total load. To do this, multiply the power consumption of 1 meter by the meter of the LED strip.
2. To accurately calculate the power of the power supply We multiply the total load by the safety factor kз.
Pbp = Ptot × kz
Since the connection diagram contains an element such as RGB controller, the final parameter of the power supply unit is determined taking into account the power of the controller - its value usually does not exceed 5 W.
Popular power supply models for connecting LED strips
Modern industry offers consumers a wide selection of power supplies for connecting LED strips. The power supply for connecting groups of LEDs is selected taking into account the parameters of the voltage required for the backlight to operate (12 or 24 V, respectively), the required power and the place of operation.
Model PV-15.
The lowest-power switching power supply for a 12V LED strip with a power of 15 W is used to connect a strip designed for a voltage of 12 volts. It has a waterproof aluminum case and a built-in surge protector that protects against voltage surges. The estimated operating time exceeds 200 thousand hours. The best option for outdoor placement. The price of the product is 560 rubles. a piece.
Model PV-40.
The design is similar to PV-15 with increased power parameters - 40 W. Designed for connecting LED strips operating on 24/12 volts. PV-40 - LED strip unit priced within 1000 rubles.
Model LV-50.
The design feature is a sealed plastic case. The switching power supply has protection against voltage surges and short circuits in the network and is intended for use in outdoor conditions.
The built-in surge filter ensures stable operation of the unit in Russian electrical networks. Operates at temperatures from minus 25 to plus 40 degrees Celsius. Operating time - more than 200 thousand hours. The price of the product is 1050 rubles.
Model LPV-100.
Medium power switching power supply - 100 W. Designed for connecting tapes with a voltage of 24/12 volts, has a sealed design and an aluminum housing. The product is characterized by protection against overvoltage, overload, short circuit. Ideal for stable operation in Russian electrical networks. The estimated period of operation is more than 200 thousand hours. LPV-100 is a high-quality power supply for LED strip, the price of which does not exceed 2250 rubles.
Model SUN-400.
A high-power switching power supply is an excellent solution for ensuring the operation of LED strips. Has protection against short circuits and voltage surges. The cooling principle is free air convection. Provides operation of tapes designed for 24/12 volt voltage in enclosed spaces, power - 400 W. Successfully passed performance tests in Russian electrical networks. The price of the product is 3600 rubles.
Often you need to power your homemade products, but there is no power supply for the required voltage. Of course, you can use batteries to check. Select the right amount to obtain the required voltage, but for constant operation this approach is irrational. Let's look at options for manufacturing power supplies for LEDs from simple and cheap to more complex and expensive.
Transformerless power supply for LEDs
The essence of such a unit is to use a ballast (quenching) capacitor. On our website there is a detailed article about such a power supply, in which you can find. In general, the scheme looks like this:
This option has a lot of disadvantages:
- No output voltage stabilization;
- no galvanic isolation (transformer);
- There is no discharge resistor on the ballast capacitor, so there is a risk of electric shock from C1.
Having accepted these shortcomings and modified the circuit, we get the following transformerless power supply for 12V LEDs.
Instead of D1, the L7812 linear stabilizer microcircuit, any other one can be installed at the required voltage (7805, etc., as well as domestic KREN stabilizers).
An alternative version of the power supply circuit for an LED strip, when assembling it yourself, is to use a zener diode or a parametric stabilizer made of a zener diode and a transistor instead of a linear stabilizer. The advantage of this solution is the flexibility in setting the stabilization voltage, because if you do not have a suitable zener diode, you can connect the other two in series and achieve the desired voltage value.
To make a homemade power supply for an LED strip, a domestic zener diode of the D818D series, designed for a voltage of about 12-13 V, is suitable.
Another way of stabilization is to assemble a current stabilizer using two transistors. The stabilization current is set by resistor R2.
R2 = 0.7 * Ist; R1 = 3.9 kOhm.
The current stabilizer strives to produce a given current; this is the best option for transformerless power supply of individual LEDs.
Conversion of ready-made power supplies to work with LEDs
Let's start with the most common power supplies - mobile phone chargers. Output voltage from 5 to 9 volts DC, stabilized circuit and galvanic isolation from the network. This makes the use of similar power supply circuits for LED strip safer than the previous option.
The simplest option would be to use a current-limiting resistor; for convenience, there is.
Circuits for cheap power supplies from chargers
First, take a look at the circuits from different chargers; they look different, but are fundamentally identical ( you can scroll through the pictures).
Most mobile phone chargers are built on the basis of a blocking generator, or, as it is also called, an autogenerator.
The rectified voltage is supplied to a circuit consisting of a power transistor, which is controlled through the base winding and base bias resistor, transformer, and feedback circuit. This is the simplest switching power supply. Suitable as a circuit for the power supply of an LED strip, if it is slightly modernized.
Principle of operation
The transformer windings are connected in such a way that at the base of the transistor and the collector winding, the voltages are induced in antiphase, in other words, “vice versa.” When the transistor opens completely through the base resistor, the increase in current in the collector winding stops and a back-EMF appears on the base winding, closing the transistor. The current in the collector circuit decreases, and after reaching zero, the process repeats.
However, this description is very simplified, given only to understand the general principle of the occurrence of high-frequency alternating current oscillations on a pulse transformer.
You may have noticed that in each of the diagrams above I have circled one of the elements in red - this is a zener diode (Zener diode). It is installed just in the voltage feedback circuit. When the output voltage reaches the stabilization voltage, negative feedback comes into play, which closes the transistor.
In more expensive ones (see the second diagram), the feedback is introduced through an optocoupler, this increases the reliability of the circuit as a whole.
The generalized circuit of the blocking generator is shown in the figure below; all other components in the chargers are needed for stabilization (feedback), indication, protection against emergency operating conditions, etc.
Making a power supply
Since the zener diode has a stabilization voltage, feedback is provided with its help. This means that in order to change the output voltage, you need to replace it with a different value Ustabil.
The output voltage of the charger is approximately equal to the rating of the stabilizer. It differs from the nominal value on a zener diode from 0.3 to 1V and depends on some features of the circuit. Please note that in the examples given, zener diodes range from 5 to 7 volts.
When the output voltage changes, the current that the charger can deliver also changes. Moreover, the change in current is inversely proportional to the magnitude of the change in voltage. Those. By increasing the voltage by half, say to 7.5 volts, the current will drop by half.
To make a power supply for LEDs with your own hands, you need to decide how you will connect the load in order to draw conclusions about the required voltage.
If you are going to power one LED or several connected in parallel, you need an output voltage of about 3 volts (). Next, select the required zener diode, for example a similar one - 3.3V. When connecting in parallel, do not forget to check the voltage through each of the LEDs and correct it with an additional resistor.
Many power supplies, not just mobile chargers, are made according to this design. More powerful and expensive models (slightly), and models with other power circuits equipped with a slightly different and easier to configure feedback. Often, which is made on a TL431 chip (or any other letters and “431” in the name).
This integrated circuit acts as a conventional zener diode. The differences are that the TL431 is an adjustable zener diode and has a 3-pin package
The output voltage is set by changing the ratio of resistors R1 and R2 (see the following diagram), below is a typical circuit of a power supply with TL431. Circled are the resistors that need to be selected for adjustment; the selection formula is as follows:
Vout = 1 + (R1/R2) *Vref, Where Vref – approximately 2.5V
Mnemonic rule: There are 2 resistors in the TL431 harness that set the stabilization voltage. The higher the upper one, the higher the voltage; accordingly, the lower the resistance, the lower the voltage the power supply will produce. The lower one – on the contrary, the greater the resistance, the lower the voltage (the upper one increases, the lower one decreases).
3 options for power supply from charger
First option. You can make an adjustable power supply in this way: replace one of the potentiometer resistors, depending on where you solder it (instead of the top or bottom), the adjustment limits will change.
The ideal option is to place a constant resistor and potentiometer in series, setting the minimum voltage level at the output of the power supply using the given formula.
Using the described methods, you can make a power supply for an LED strip with your own hands from almost any old power supply, charger, etc. However, in some cases you will have to wind the secondary winding with several turns; this method is somewhat more difficult and we will not consider it.
Second scheme. The adjustment is similar for R7 and R5.
Such a DIY power supply is superior to transformerless power supply for LEDs in all respects. And what about the price - don’t forget that if you rummage through your pantry, you’ll probably find a couple of blanks.
Third option- this is to modernize or complete old transformer power supplies.
If the output voltage from the diode bridge exceeds 14 volts, install L7812 according to the indicated circuit and get a ready-made power supply for LED strip, made by yourself.
If you want to make a power supply for individual LEDs, the circuit will only change in the rating of the stabilizer - you will need to install a 3-volt model (7803). Or assemble a parametric stabilizer as described above. This power supply is better than the first one reviewed, but worse than the second one. It is larger and has lower efficiency.
Power supply for LED strip from a laptop charger
Power supplies from laptops, monitors and other household and computer equipment have a voltage of 12 to 19 or more volts. If the voltage is 12V - excellent, this is ideal for an LED strip. But how can you change the output voltage if it doesn't suit your needs?
This is an adjustable pulse step-down voltage converter made on a fairly old, reliable and popular microcircuit - LM2596. The model shown in the photo has voltage and current regulation, which allows it to be used as a driver for high-power LEDs, providing very high-quality power.
In the photo you can see the abbreviation ADJ (adjustable) in the designation - which indicates that this is an adjustable model. There are ready-made circuits and separate ICs for sale for working with a fixed output voltage, namely: 3V, 5V and 12V. In versions with a current of 2 and 3 Amperes each, they have a slightly simplified circuit.
The purpose of the elements is described, the only difference is that in the diagram above there is no current stabilization and no voltage regulation, as in the previous photo.
Step-down voltage converters using the LM2596 are quite popular. You can find them in radio parts stores, but you can buy them on Aliexpress for much less.
Their connection diagram is simple, the input and output contacts are labeled, some boards are supplied with soldered clamp terminals. Connect it to a ready-made power supply at a higher voltage (from a laptop, for example) and the power supply for LED lamps is ready.
This option is suitable for beginners if you do not want to get into the circuit with a soldering iron or there is no way to get to the elements of the block to modify the circuit (in the case of a difficult-to-disassemble case and when the parts are filled with compound).
LED strip power supply repair
Many power supplies designed for medium and high power (30 W or more) are built on an integrated driver with a built-in power switch, such as KA5l0365, FSDH065RN, etc. Such solutions are also used in household appliances, for example, in power supplies for DVD players. Such microcircuits are interchangeable; you just need to determine the pinout of the burnt chip and install the one you managed to find.
To repair the power supply for a 12V LED strip (and not only), the circuit remains almost unchanged. You need to make a connection similar to what is shown below. Of course, taking into account the pinout.
More complex and reliable blocks are built on PWM controllers:
- TL494;
- KIA494AP;
- MB3759;
- KA7500;
They are similar, below is a power supply diagram for an LED strip using them:
The PWM controller is located at the bottom of the circuit; adjustment is made using P1 (on the right in the diagram). By selecting its value, you can achieve the desired output voltage, somewhat similar to adjusting the 431 stabilizer.
Even if your unit does not have a potentiometer or trimmer, you can install it yourself by replacing the constant one, similar to the diagram I provided.
When repairing, look at the signal at the PWM output, power switches T12 and T13 connected to pins 8 and 11 of the TL494.
The picture below shows the adjustment more clearly; the potentiometer is connected to pin 1 of the IC.
Thus, you can experimentally make power for an LED strip with your own hands from any power supply on a 494 PWM controller.
Almost all power supplies can be reconfigured with your own hands within narrow limits to the required supply voltage for the LED strip. At the same time, you will get by with minimal costs.
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:
- Minimum energy consumption;
- Surge filters, which makes it possible to operate in a wide variety of conditions;
Blocks rated at 24V are used to connect SMD5050 LEDs with a calculation of 120 pieces per 1 meter.
Description
Switching power supply units are a small device with a housing of 180x96x38 mm.
Specifications:
- The input current is 1.5 - 2.5 amperes.
- Input power – 115 – 230 V.
- Frequency – 50 – 60 hertz.
- Operating voltage – 220 volts (our standard networks).
- Output voltage – 12 V.
- Output current – 15 A.
- Power – 180 watts.
- Safety features: overload and short circuit protection. Some types are moisture resistant.
This is one of the most common types. The size of some models differs from each other.
Here are some examples:
- 165x65x40;
- 115x80x37;
- 165x100x44;
- 255x75x45;
Other differences in some species:
- The current strength has a decent range: from 1.25 to 41 A.
- Power ranges from 1 to 1000 W.
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.
Purpose and principle of operation
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.
Kinds
Designations in the photo:
- Compact and sealed.
- Sealed in aluminum housing.
- Open.
- Compact network.
12-volt units come in two main types:
- Voltage stabilized– 12/24 volts. Twelve volt ones are used mainly to connect G4 and MR16.
- Current stabilized– constant/variable.
In addition to these differences, the following types are available:
- Sealed. Protection degree – IP66 and 67. The small case protects the device from dust and water. Has a built-in potentiometer that functions as a current adjustment. Units with low power are produced in plastic housings, while high power units are sealed in aluminum.
- Semi-hermetic. Degree of protection – IP54. Suitable for outdoor use as the adapter body is metal and moisture resistant. Power varies from 10 to 360 watts.
- Leaky. For indoor use only. They are made in a metal or plastic corrugated casing.
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:
- Power, which the tape consumes.
- Voltage, necessary to power the tape.
- Protection from moisture.
Power calculation
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:
- You need to multiply 15 by 5. The output is 75 W.
- Now add ¼ of 75. This is 18.75.
- Add to 75, we get 93.75 W. This is the minimum power of the block in our example.
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.
How to do it yourself?
To make your own power supply you will need:
- A lot of time.
- A few details.
What we may need to assemble the LED strip power supply:
- frame;
- tape of the required length;
- pay;
- cord;
- screwdriver;
We present to your attention the assembly diagram for a 12V power supply:
Designations:
- C1 – ballast capacitor.
- C2 – anti-aliasing filter.
- VD1 – VD4 – diodes.
- VD5 – zener diode.
- R1 – R3 – resistors.
Step by step guide:
- The best option would be a transformerless power supply with a ballast capacitor.
- The capacitor suppresses the mains voltage, which is then fed to a rectifier assembled on diodes. From the rectifier it goes to the smoothing filter.
- Resistors ensure fast discharge of capacitors. R1 limits the current when connected, the zener diode limits the output voltage, providing 12 volts.
- The current depends on the value of capacitor C1 for the power supply.
- You should not power the LEDs with the maximum permissible current.
Connection
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:
- Phase.
- Zero.
- V+ (output voltage).
- COM (the tape is connected there).
- We expose two wires of the cord and connect them to phase and neutral.
- Insert the plug into the socket. When the green LED lights up, it means that the power supply is ready for use.
- Any unit designed to power LED lamps, must comply with lighting standards.
- It is not recommended to disassemble the case and try to make any changes. Re-soldering the adapter circuit is difficult and time-consuming. Even for an electronics engineer.
- Depending on the power of the power supply, several tapes can be connected to it. There is an RGB amplifier for this. It receives a signal from one tape and distributes it to others. At the same time, the synchronicity of color changes and brightness is not lost.
Attention! If you try to connect the tape directly to an outlet, it will start to smoke and, naturally, will not work after that.
