Homemade power supply with regulation. Voltage regulated power supply: technical specifications. Filter and stabilization unit

Somehow recently I came across a circuit on the Internet for a very simple power supply with the ability to adjust the voltage. The voltage could be adjusted from 1 Volt to 36 Volt, depending on the output voltage on the secondary winding of the transformer.

Take a close look at the LM317T in the circuit itself! The third leg (3) of the microcircuit is connected to capacitor C1, that is, the third leg is INPUT, and the second leg (2) is connected to capacitor C2 and a 200 Ohm resistor and is an OUTPUT.

Using a transformer, from a mains voltage of 220 Volts we get 25 Volts, no more. Less is possible, no more. Then we straighten the whole thing with a diode bridge and smooth out the ripples using capacitor C1. All this is described in detail in the article on how to obtain constant voltage from alternating voltage. And here is our most important trump card in the power supply - this is a highly stable voltage regulator chip LM317T. At the time of writing, the price of this chip was around 14 rubles. Even cheaper than a loaf white bread.

Description of the chip

LM317T is a voltage regulator. If the transformer produces up to 27-28 volts on the secondary winding, then we can easily regulate the voltage from 1.2 to 37 volts, but I would not raise the bar to more than 25 volts at the transformer output.

The microcircuit can be executed in the TO-220 package:

or in D2 Pack housing

It can pass a maximum current of 1.5 Amps, which is enough to power your electronic gadgets without voltage drop. That is, we can output a voltage of 36 Volts with a current load of up to 1.5 Amps, and at the same time our microcircuit will still output 36 Volts - this, of course, is ideal. In reality, fractions of volts will drop, which is not very critical. With a large current in the load, it is more advisable to install this microcircuit on a radiator.

In order to assemble the circuit, we will also need a variable resistor of 6.8 Kilo-Ohms, or even 10 Kilo-Ohms, as well as a constant resistor of 200 Ohms, preferably from 1 Watt. Well, we put a 100 µF capacitor at the output. Absolutely simple scheme!

Assembly in hardware

Previously, I had a very bad power supply with transistors. I thought, why not remake it? Here is the result ;-)

Here we see the imported GBU606 diode bridge. It is designed for a current of up to 6 Amps, which is more than enough for our power supply, since it will deliver a maximum of 1.5 Amps to the load. I installed the LM on the radiator using KPT-8 paste to improve heat transfer. Well, everything else, I think, is familiar to you.

And here is an antediluvian transformer that gives me a voltage of 12 volts on the secondary winding.

We carefully pack all this into the case and remove the wires.

How do you like it? ;-)

The minimum voltage I got was 1.25 Volts, and the maximum was 15 Volts.

I set any voltage, in this case the most common are 12 Volts and 5 Volts

Everything works great!

This power supply is very convenient for adjusting the speed of a mini drill, which is used for drilling circuit boards.

Analogues on Aliexpress

By the way, on Ali you can immediately find a ready-made set of this block without a transformer.

Too lazy to collect? You can buy a ready-made 5 Amp for less than $2:

You can view it at this link.

If 5 Amps is not enough, then you can look at 8 Amps. It will be enough for even the most seasoned electronics engineer:

When doing something regularly, people strive to make their work easier by creating various devices and devices. This fully applies to the radio business. When assembling electronic devices with one of important issues, the question of nutrition remains. Therefore, one of the first devices that a novice radio amateur often assembles is this.

Important characteristics of the power supply are its power, stabilization of the output voltage, and the absence of ripple, which can manifest itself, for example, when assembling and powering an amplifier, from this power supply in the form of background or hum. And finally, it is important for us that the power supply is universal so that it can be used to power many devices. And for this it is necessary that it can produce different output voltages.

A partial solution to the problem may be a Chinese adapter with switching the output voltage. But such a power supply does not have the ability to be smoothly adjusted and does not have voltage stabilization. In other words, the voltage at its output “jumps” depending on the supply voltage of 220 volts, which often sags in the evenings, especially if you live in a private house. Also, the voltage at the output of the power supply unit (PSU) may decrease when a more powerful load is connected. The power supply proposed in this article, with stabilization and regulation of the output voltage, does not have all these shortcomings. By rotating the variable resistor knob, we can set any voltage in the range from 0 to 10.3 volts, with the possibility of smooth adjustment. We set the voltage at the output of the power supply according to the readings of the multimeter in voltmeter mode, D.C.(DCV).

This can come in handy more than once, for example, when testing LEDs, which, as you know, do not like being supplied with a voltage that is too high compared to the rated voltage. As a result, their service life can be sharply reduced, and in particularly severe cases, the LED can burn out immediately. Below is a diagram of this power supply:

The design of this RBP is standard and has not undergone significant changes since the 70s of the last century. The first versions of the circuits were using germanium transistors, later versions were using a modern element base. This power supply is capable of delivering power up to 800 - 900 milliamps, provided there is a transformer that provides the required power.

The limitation in the circuit is the diode bridge used, which allows currents of a maximum of 1 ampere. If you need to increase the power of this power supply, you need to take a more powerful transformer, a diode bridge and increase the radiator area, or if the dimensions of the case do not allow this, you can use active cooling (cooler). Below is a list of parts required for assembly:

This power supply uses the domestic high-power transistor KT805AM. In the photo below you can see it appearance. The adjacent figure shows its pinout:

This transistor will need to be attached to the radiator. In the case of attaching the radiator to the metal body of the power supply, for example, as I did, you will need to place a mica gasket between the radiator and the metal plate of the transistor, to which the radiator should be adjacent. To improve heat transfer from the transistor to the radiator, you need to use thermal paste. In principle, any one used for application to a PC processor will do, for example the same KPT-8.

The transformer should produce a voltage of 13 volts on the secondary winding, but in principle a voltage within 12-14 volts is acceptable. The power supply contains a filtering electrolytic capacitor with a capacity of 2200 microfarads (more is possible, less is not advisable), for a voltage of 25 volts. You can take a capacitor designed for more voltage, but it should be remembered that such capacitors are usually larger in size. The figure below shows a printed circuit board for the sprint-layout program, which can be downloaded in the general archive, attached archive.

I assembled the power supply not exactly using this board, since my transformer with a diode bridge and a filter capacitor were on a separate board, but this does not change the essence.

A variable resistor and a powerful transistor, in my version, are connected by hanging mounting, on wires. The contacts of the variable resistor R2 are marked on the board, R2.1 - R2.3, R2.1 is the left contact of the variable resistor, the rest are counted from it. If, nevertheless, during connection the left and right contacts of the potentiometer were confused, and the adjustment is carried out not from the left - minimum, to the right - maximum, you need to swap the wires going to the extreme terminals of the variable resistor. The circuit provides a power-on indication on the LED. Switching on and off is carried out using a toggle switch, by switching the 220 volt power supply supplied to the primary winding of the transformer. This is what the power supply looked like at the assembly stage:

Power is supplied to the power supply through the computer's native ATX power supply connector, using a standard detachable cable. This solution allows you to avoid the tangle of wires that often appears on a radio amateur’s desk.

The voltage at the output of the power supply is removed from laboratory clamps, under which any wire can be clamped. You can also connect standard multimeter probes with crocodiles at the ends to these clamps, by inserting them on top, for more convenient supply of voltage to the assembled circuit.

Although, if you want to save money, you can limit yourself to simple wiring at the ends with alligator clips, clamped using laboratory clamps. If using a metal housing, place a suitable size casing on the clamp securing screw to prevent the clamp from shorting to the housing. I have been using this type of power supply for at least 6 years now, and it has proven the feasibility of its assembly and ease of use in the daily practice of a radio amateur. Happy assembly everyone! Especially for the site " Electronic circuits "AKV.

So the next device has been assembled, now the question arises: what to power it from? Batteries? Batteries? No! The power supply is what we will talk about.

Its circuit is very simple and reliable, it has short circuit protection, smooth adjustment output voltage.
A rectifier is assembled on the diode bridge and capacitor C2, circuit C1 VD1 R3 is a reference voltage stabilizer, circuit R4 VT1 VT2 is a current amplifier for power transistor VT3, protection is assembled on transistor VT4 and R2, and resistor R1 is used for adjustment.

I took the transformer from an old charger from a screwdriver, at the output I got 16V 2A
As for the diode bridge (at least 3 amperes), I took it from an old ATX block as well as electrolytes, a zener diode, and resistors.

I used a 13V zener diode, but the Soviet D814D is also suitable.
The transistors were taken from an old Soviet TV; transistors VT2, VT3 can be replaced with one component, for example KT827.

Resistor R2 is a wirewound with a power of 7 Watts and R1 (variable), I took a nichrome one, for adjustment without jumps, but in its absence you can use a regular one.

It consists of two parts: the first contains the stabilizer and protection, and the second contains the power part.
All parts are mounted on the main board (except for power transistors), transistors VT2, VT3 are soldered onto the second board, we attach them to the radiator using thermal paste, there is no need to insulate the housing (collectors). The circuit was repeated many times and does not need adjustment. Photos of two blocks are shown below with a large 2A radiator and a small 0.6A.

Indication
Voltmeter: for it we need a 10k resistor and a 4.7k variable resistor and I took an indicator m68501, but you can use another one. From resistors we will assemble a divider, a 10k resistor will prevent the head from burning out, and with a 4.7k resistor we will set the maximum deviation of the needle.

After the divider is assembled and the indication is working, you need to calibrate it; to do this, open the indicator and glue clean paper onto the old scale and cut it along the contour; it is most convenient to cut the paper with a blade.

When everything is glued and dry, we connect the multimeter in parallel to our indicator, and all this to the power supply, mark 0 and increase the voltage to volts, mark, etc.

Ammeter: for it we take a resistor of 0.27 ohm!!! and variable at 50k, The connection diagram is below, using a 50k resistor we will set the maximum deviation of the arrow.

The graduation is the same, only the connection changes, see below; a 12 V halogen light bulb is ideal as a load.

List of radioelements

For radio amateurs, and modern people in general, an indispensable thing in the house is a power supply unit (PSU), because it has a very useful function - voltage and current regulation.

At the same time, few people know that it is quite possible to make such a device with due diligence and knowledge of radio electronics with your own hands. For any radio amateur who likes to tinker with electronics at home, homemade laboratory power supplies will allow him to practice his hobby without restrictions. Our article will tell you how to make an adjustable power supply with your own hands.

What you need to know

Power supply with current and voltage regulation modern house- a necessary thing. This device, thanks to its special device, can convert the voltage and current available in the network to the level that a particular electronic device can consume. Here is an approximate scheme of work according to which you can make such a device with your own hands.

But ready-made power supplies are quite expensive to buy for specific needs. Therefore, today very often converters for voltage and current are made by hand.

Pay attention! Homemade laboratory power supplies can have different dimensions, power ratings and other characteristics. It all depends on what kind of converter you need and for what purpose.

Professionals can easily make a powerful power supply, while beginners and amateurs can start with a simple type of device. In this case, depending on the complexity, a very different scheme can be used.

What to consider

The regulated power supply is a universal converter that can be used to connect any household or computing equipment. Without it, not a single home appliance will be able to function normally.
Such a power supply consists of the following components:

• transformer;
• converter;
• indicator (voltmeter and ammeter).
• transistors and other parts necessary to create a high-quality electrical network.

The diagram above shows all the components of the device.
In addition, this type of power supply must have protection for high and low current. Otherwise, any abnormal situation may lead to the fact that the converter and connected to it electrical appliance it will just burn out. This result can also be caused by improper soldering of board components, incorrect connection or installation.
If you are a beginner, then in order to make an adjustable type of power supply with your own hands, it is better to choose a simple assembly option. One of simple types The converter is a 0-15V PSU. It has protection against excess current in the connected load. The diagram for its assembly is located below.

Simple assembly diagram

This is, so to speak, a universal type of assembly. The diagram here is understandable to anyone who has held a soldering iron at least once in their hands. The advantages of this scheme include the following points:

• it consists of simple and affordable parts that can be found either on the radio market or in specialized radio electronics stores;
• simple type of assembly and further configuration;
• here the lower limit for voltage is 0.05 volts;
• dual-range protection for current indicator (at 0.05 and 1A);
• wide range for output voltages;
• high stability in the functioning of the converter.

Diode bridge

In this situation, the transformer will provide a voltage that is 3V higher than the maximum required output voltage. It follows from this that a power supply capable of regulating voltage up to 20V requires a transformer of at least 23 V.

Pay attention! The diode bridge should be selected based on the maximum current, which will be limited by the available protection.

A 4700 µF filter capacitor will allow equipment sensitive to power supply noise to avoid background noise. To do this, you will need a compensation stabilizer with a suppression coefficient for ripples of more than 1000.
Now that we have understood the basic aspects of assembly, we need to pay attention to the requirements.

Device requirements

To create a simple, but at the same time high-quality and powerful power supply with the ability to regulate voltage and current with your own hands, you need to know what requirements exist for this type of converter.
These technical requirements look like this:

• adjustable stabilized output for 3–24 V. In this case, the current load must be at least 2 A;
• unregulated 12/24 V output. This assumes a large current load.

To fulfill the first requirement, you should use an integral stabilizer. In the second case, the output must be made after the diode bridge, so to speak, bypassing the stabilizer.

Let's start assembling

Transformer TS-150–1

Once you have determined the requirements that your permanent regulated power supply must meet, and the appropriate circuit has been selected, you can begin the assembly itself. But first of all, let's stock up on the parts we need.
For assembly you will need:

• powerful transformer. For example, TS-150–1. It is capable of delivering voltages of 12 and 24 V;
• capacitor. You can use a 10000 µF 50 V model;
• chip for stabilizer;
• strapping;
• details of the circuit (in our case, the circuit shown above).

After this, according to the diagram, we assemble an adjustable power supply with our own hands in strict accordance with all the recommendations. The sequence of actions must be followed.

Ready power supply

The following parts are used to assemble the power supply:

• germanium transistors (mostly). If you want to replace them with more modern silicon elements, then the lower MP37 should definitely remain germanium. MP36, MP37, MP38 transistors are used here;
• A current-limiting unit is assembled on the transistor. It provides monitoring of the voltage drop across the resistor.
• Zener diode D814. It determines the regulation of the maximum output voltage. It absorbs half of the output voltage;

Pay attention! Since the D814 zener diode takes exactly half the output voltage, it should be selected to create a 0-25V output voltage of approximately 13V.

• the lower limit in the assembled power supply has a voltage indicator of only 0.05 V. This indicator is rare for more complex converter assembly circuits;
• dial indicators display current and voltage indicators.

Assembly parts

To accommodate all the parts, you must choose a steel case. It will be able to shield the transformer and power supply board. As a result, you will avoid situations of various types of interference for sensitive equipment.

The resulting converter can be safely used to power any household equipment, as well as experiments and tests carried out in a home laboratory. Also, such a device can be used to assess the performance of a car generator.

Conclusion

Using simple circuits to assemble an adjustable type of power supply, you will be able to get your hands on and in the future make more complex models with your own hands. You should not take on backbreaking work, as in the end you may not get the desired result, and a homemade converter will work ineffectively, which can negatively affect both the device itself and the functionality of the electrical equipment connected to it.
If everything is done correctly, then at the end you will get an excellent power supply with voltage regulation for your home laboratory or other everyday situations.

Selecting a street motion sensor to turn on the lights

A universal power supply, with which you can get all the voltages that may be needed in amateur radio and just everyday activities, should be in every home. And of course, the power supply must have good power - provide an output current not of 0.5 A, like cheap Chinese adapters, but several amperes to connect even lead batteries from a car for charging, or electric motors. Of course, I want the voltage range to also matter. Most circuits are limited to 12 volts, at best 20. But sometimes you need both 24 and 36 V. Is it difficult to create such a power supply yourself? No, because the circuit will only need a dozen parts. Here is a very simple, universal power supply with adjustable supply voltage. The maximum output voltage is 36 V - it is adjustable in the range from 1.2 to (vcc - 3) volts.

Regulated power supply circuit

Transistor Q1 is a high-power PNP Darlington, used to increase the current of the LM317 IC. The LM317L itself, without a heatsink, can supply 100 mA, which is enough to drive a transistor. Elements D1 and D2 are protective diodes, because when the circuit is turned on, the charge of the capacitors can damage the transistor or stabilizer.

To eliminate high-frequency noise, we install 100 nF capacitors in parallel with electrolytic capacitors, because electrolytic ones have large ESR and ESL values ​​and cannot clearly eliminate high-frequency noise. Here is a sample PCB design for this circuit.

Notes

• Transistor Q1 needs a heatsink and preferably a small fan.
• The maximum output power of the circuit is 125 watts.
• R1 - 2 W, other resistors - 0.25 watt.
• All capacitors are 50V.
• RV1 - 5 kOhm regulator.
• A transformer is required for 36 V 5 A. With a power of 150 watts and above.
• The terminals for connecting the output wires are the same as for speakers in amplifiers, screw type.