Switching power supply 12V 5A: general information, diagram, DIY device manufacturing process

A switching power supply is an inverter system in which an alternating voltage is converted into direct voltage, and then pulses of increased frequency are formed from it. Such a device is quite expensive and only wealthy people can buy it. All those who do not belong to this category try to make a device with their own hands. To do this, you will need the necessary materials and a circuit of a 12 V 5A switching power supply.

General information

Before you make a do-it-yourself switching power supply, you need to study in detail its design features, principle of operation, advantages and disadvantages. With the help of this information, you can speed up the creation process, as well as make the device better and more durable.

Components

Most often, a homemade switching power supply is made according to a standard scheme using some important elements. It is used to adjust the input voltage when powering LED lamps or other lighting fixtures. The block design includes

several components:

1. Pulse transformer. It is installed between the inlet and outlet parts of the structure and serves to carry out the pulse isolation process.
2. PTC thermistor. This part of the device is made from a variety of semiconductors and has a positive temperature coefficient. It is used as a key protection mechanism.
3. Capacitor. This structural element is designed for different loads and acts as a filter element (removes the remaining pulse peaks).
4. Drivers. With their help, the resistance arising in the circuit is extinguished.
5. Field effect transistors. They are selected based on the maximum voltage and resistance. At low rates of these two parameters, the efficiency increases significantly, and the degree of heating decreases during operation.
6. Typical transformer. It has a standard design and is used for high voltage reduction.

Principle of operation

The switching power supply is distinguished by its simplicity of operation. It can be easily understood not only by a specialist, but also by a beginner with basic knowledge in this area. Because of this, devices are considered the most affordable and are often used for various purposes. They work as follows:

1. The AC input voltage is converted to DC.
2. Then it takes the form of a rectangular pulse of high frequency and is fed to the transformer.
3. There, with the help of negative feedback, the voltage stabilization process takes place.

Feedback can be created in one of two ways. Both of them allow you to perform the assigned functions efficiently and avoid the occurrence of unforeseen situations. Feedback methods:

1. No decoupling (using a resistor voltage divider).
2. Galvanically isolated (transformer winding output or optocoupler).

The process of maintaining the output voltage is similar.

Advantages and disadvantages

A self-made impulse power supply unit, like any other device, has several advantages. Thanks to them, the design is very popular and is often used in a particular field of human activity. The positive aspects of the power supply include the following factors:

1. High stabilization factor. Thanks to this indicator, power conditions are provided that reduce the negative impact on the sensitive electronic elements of the device.
2. High efficiency. All modern models are equipped and tuned to minimize unwanted losses, which will automatically lead to an increase in efficiency. In some cases, this figure can reach 98%.
3. Susceptibility to sudden power surges. This is one of the main advantages of the design, which allows to increase the life of electronic elements.
4. The frequency of the incoming current has practically no effect on the operation of the input parts of the structure.
5. Remote control capability. Some newer models have a special function that allows you to control the device from a short distance.
6. Light weight and dimensions. These parameters simplify the process of transporting the power supply and increase its popularity among consumers.
7. Cheapness. A switching power supply is much cheaper than a linear one.

Despite the large number of advantages, the design also has several disadvantages. They must be taken into account, as they will avoid malfunctions and reduce the risk of poor-quality operation of the device. Among the disadvantages are the following:

1. Difficulties in self-adjusting the parameters of the device.
2. Strong impulse noise.
3. The need to supplement the circuit with power factor compensators.
4. The complexity of carrying out repair and maintenance work.
5. Low degree of reliability.

DIY making

In order for the device to work correctly and perform the functions assigned to it, a number of rules must be observed. With their help, you can achieve the desired result and reduce the likelihood of errors.

Professional recommendations

During the manufacture of a switching power supply, one should take into account not only the advice of the part manufacturers, but also the recommendations of specialists. They will help beginners avoid most of the simple mistakes and get the job done in the shortest amount of time. Professional Tips:

1. In most cases, the power supply circuit does not require special filters and feedback.
2. Of the many field-effect transistors, it is recommended to buy parts of the IR type. They withstand high temperatures well and do not deteriorate under prolonged exposure to heat.
3. If, in a self-assembled structure, the transistors will become very hot during operation, then an additional cooling device (fan) should be installed.

Required materials and tools

Before proceeding with the manufacture of the device, you need to prepare all the necessary materials and tools. Thanks to this, it will be possible not to be distracted during work in order to find this or that item. In the process of creating a device you will need:

• any PTC thermistor;
• capacitors with a capacity of at least 220 μF;
• diode assembly;
• field-effect transistors with good resistance (IRF840, IRF740);
• drivers IR2153D, IR2153, IR2152;
• transformer (you can use a device removed from old computer system units);
• diodes from the HER family.

In addition to the constituent parts of the structure, it is necessary to prepare various tools. With their help, the assembly of the device will be carried out, so they must be of high quality and convenient for use.

Required tools:

• pliers;
• screwdrivers of different sizes;
• tweezers;
• soldering equipment;
• consumables for soldering.

Build process

After all the preparatory activities have been completed, you can start assembling the device yourself. The scheme of switching power supplies is drawn up in advance. This work can be done independently or with the help of a specialist.

The first option is much cheaper, but it requires the master to have knowledge in the field of electronics and a lot of time.

Step-by-step instruction:

1. First of all, a PTC thermistor is installed at the input and securely fixed.
2. Then the design is complemented by diode bridges.
3. At the next stage, the drivers used to control the operation of the gates of the field-effect transistors are mounted.
4. Field-effect transistors are attached without shortening the flanges.
5. After that, fastening to the radiator is carried out. This work must be done using insulating gaskets and special washers.
6. Transformers are mounted with short-circuited terminals.
7. Diodes are placed at the output.

Testing the device

In order to check the assembled pulsed power source for operability, you need to perform a few simple steps. They will help identify various problems and errors made during the assembly process. Procedure:

1. The first short-term connection of the device to the circuit is performed.
2. If everything is done correctly, then the lamp should light up, signaling the power supply to the device.
3. Then leave the power supply in working order for a few minutes.
4. After this time, it is necessary to turn off the device and check the temperature of all its parts. Heating one or more elements will indicate an error in the assembly process.
5. At the second start, the voltage value is determined. This operation can be performed using a special tester.
6. A working power supply is left for about 1 hour.
7. After a specified period of time, the elements are checked for the degree of heating.
8. If none of the cells get hot, then they are all checked for high current after power off.

Safety engineering

During the operation of the impulse unit, it is necessary to adhere to simple safety rules. They will help to avoid injuries of varying severity and reduce the likelihood of an emergency. Basic Precautions:

1. Repair or maintenance work should only be carried out when the unit is disconnected from the mains. This will help to avoid electric shock and all problems associated with it.
2. Power capacitors can remain energized for a long time even after the unit is turned off. Because of this, it is forbidden to perform any actions with the device immediately after turning it off.
3. It is forbidden to store flammable objects and combustible materials near the operating unit. A small spark can ignite and cause many problems.
4. It is not recommended to repair the structure if there are grounded devices next to it.
5. Do not store or use the device in a humid environment, as this may cause a short circuit.
6. A master working with a pulsed energy source must stand on a special mat made of dielectric material. This simple measure will greatly reduce the risk of electric shock.
7. Do not repair the device while standing on a floor of cement or any other conductive material.
8. It is not recommended to leave a working homemade unit unattended.
9. When you first turn on a self-made unit, you must carefully check all structural elements for safety.
10. It is important to avoid the ingress of water or any other liquids on the electrical parts of the device.
11. Preventive and repair measures should be carried out using special protective clothing (armbands, gloves) and tools with insulated handles.
12. Keep your homemade device out of the reach of children and pets.
13. In the event of any accident or unforeseen situation, you must immediately de-energize the equipment. Only then can you search for the cause of the breakdown and eliminate it.

A pulsed energy source is a useful and necessary device that you can not only buy ready-made, but also make your own hands. The second option is more popular, since it allows you to get a high-quality device with minimal financial and time costs.

By following professional advice and safety rules, you can significantly reduce the risk of injury and avoid accidents.