Disinsection
How to make an adjustable power supply from a computer. How to make an adjustable power supply with your own hands How to make an adjustable

How to make an adjustable power supply from a computer. How to make an adjustable power supply with your own hands How to make an adjustable

Installation of an adjustable floor is a quick, economical and fairly simple process of creating a rough floor covering with a perfectly flat plane. This article will introduce you to the new technology, tell you about the varieties of adjustable floors, the scope and installation process.

What problems does adjustable floor solve?

Adjustable lags are a technology for creating an exceptionally light floor using the dry repair methodology, so their main scope is high-rise buildings and old buildings, where an increase in the load on the floors is fraught with trouble. The technology is especially relevant if it is necessary to raise the floor level by 120 mm or more, with which a dry screed can no longer cope.

In terms of environmental friendliness and practicality, a properly installed floor meets the characteristics of a stationary log system. The sound insulation of such a floor is quite good, the heat transfer to the lower floors is minimal due to the reduction of cold bridges. The space between the lags has continuous ventilation, so mold and fungus do not start in the floor filler.

Another feature of such a floor is the ability to create a perfectly even coating for tiles or self-leveling floors in the shortest possible time - 7-8 m 2 for one hour of work by two people and up to 3 m 2 when working alone.

Installing the lag system on metal brackets

If you need to lay the floor in a small room, it is better not to use the original technology. Firstly, this is an unreasonably long search for components, and secondly, it is better to lay the floor on adjustable logs on an area of more than 6 m 2, in smaller spaces the savings in time and money are not so noticeable. Instead, you can use the installation of a log on metal brackets.

For laying, a beam of 60x60 mm is required with a moisture content of not more than 10% without traces of defects and warpage. It is also necessary to purchase or manufacture metal U-shaped brackets with a wall thickness of at least 2.5 mm and a distance between the shelves corresponding to the thickness of the timber. In each shelf at a distance of 30 mm from the end there should be a hole with a diameter of 11 mm.

On the floor, mark the lines along which the lag is planned to be installed. Lay the first log along a long wall with an indent of 20 cm, all subsequent logs in increments of 40 cm. To splice the log of one row, use two brackets installed in a row. Install all brackets along the marking lines and fasten each to the concrete with two 6x60 quick-mount dowels with a “fungus” side.

When all the brackets are installed, set the row of logs, which is the outermost from the wall, on a horizontal level, placing trimmings of beams and wood chips under them. At the highest section of the overlap, the beam should protrude 3-5 mm above the bracket. Through the perforation in the shelves of the bracket, fix the beam with two self-tapping screws on both sides.

Using lacing or a laser level, transfer the level of the first row to the last, align the bars and temporarily fix them in the brackets with self-tapping screws. Tighten the lacing or use the laser adjustment on the target to line up all the other lugs. After temporarily fixing the logs, drill them with a 12 mm drill through the holes in the brackets, insert the bolts and tighten them with a self-locking nut.

Installation of an adjustable floor on bolt racks

To install the floor according to the original technology, it is necessary to purchase plastic bolt-racks 100 or 150 mm long and metal dowel-nails 6x40 mm in the amount of about 5-6 pcs. per m 2 floor. Special logs with holes and threads can be replaced with a regular beam 50x50 mm with a moisture content of up to 10%, but you will need a wood drill and a machine tap with a diameter of 24 mm in increments of 3 mm.

The marking for installing the lag starts from the baseline, which has an indent from the wall equal to the length of the plywood sheet. In rooms with normal traffic, the extreme logs should be 15 cm from the wall, the step between the other logs is 40-45 cm. If the load on the floor is higher than usual, the distance from the walls will be less than 10 cm, and the installation step - up to 30 cm.

Prepare the bars: drill holes in them strictly perpendicular to the surface 10 cm from the edges, then evenly distribute the remaining holes along the length so that the distance between them is no more than 40-50 cm. Cut the threads in the holes with a tap and screw the bolt-racks into them. When screwing in the uprights, pre-adjust their length according to the lifting height. Use a hex wrench to screw in the bolt posts.

Install the bars along the marking lines, orienting the racks with the hex holes up. The ends of the lag should be 10 cm from the wall. Make a preliminary adjustment with an allowable error of 1 cm, bringing the lags to the design height. Through the hole inside the bolt post, mark the drilling points with a long drill, then move the logs and make 6 mm holes in the concrete floor to a depth of 50 mm.

First, fix the extreme lag racks: lower the dowel-nail into the hole and wedge it using a hammer and a metal rod or a drill from a perforator. By rotating the fixed racks, accurately level the lags using lacing or laser marking. Screw the center posts until they hit the floor and secure them with dowel nails. Make the final adjustment of the floor using a building level that covers at least three logs. Logs can be spliced at the end with a hemming in half a tree for a length of up to 5 cm and with subsequent fastening of the joint with an M10 bolt.

Rough coating device

When the logs are installed, and the space between them is filled with insulation, the flooring is made. To create a solid and even surface, it is necessary to lay two layers of moisture-resistant plywood with a thickness of 12 mm or more on the logs.

The first layer is laid with the long side across the log and attached to the beams with 55 mm self-tapping screws. The fastening step of the screws is 15-17 cm along the edges and 20-25 cm in the center of the sheet. Screw the fasteners no closer than 15 mm from the end of the plywood and flush the hats.

The second row of the first layer begins with trimming half of the sheet to provide half the length between the joints. The thickness of the joints should not exceed 2-3 mm, and the distance from the walls should not exceed 15 mm. When the first layer of plywood is laid, mark the lag on the surface.

Lay the sheets of the second layer perpendicular to the sheets of the first. If necessary, cut the floor elements so that the distance between the joints in the first and second layers is at least 20 cm. Fasten the sheets together with 35 mm self-tapping screws, at least 30 pieces per 1 m 2 with an installation step along the edge of 30 cm. Fasten the second layer to lags with self-tapping screws 65 mm in at least 15 places per 1 m 2. Permissible butt gap in the second layer is 4 mm, the distance from the walls is no more than 6 mm.

After installing the second layer of plywood, remove dust and sawdust from the surface of the sheets, then apply two layers of adhesive primer, regardless of what the flooring will be. The gaps between the plates and from the walls must be filled with polyurethane foam, or better with silicone sealant. On top of the floor on adjustable logs, you can lay any type of floor covering and even perform a preparatory screed.

The technology, new for many of our compatriots, makes it possible to significantly reduce the time for arranging floor coverings. Like any technology, in addition to its advantages, it also has rather “problematic” characteristics. But this is the professionalism of builders, in order to be able to choose among the numerous options for flooring the one that will be optimal in this particular case.

Finishing floor coverings are installed on wooden logs (in the case of floorboards) or on a solid base of plywood or OSB sheets (in the case of laminate or soft flooring).

A very important point during the construction of any floors is that the bearing surface must be in a strictly horizontal position.

It is very difficult to achieve such a result with the help of fixed logs; it is often necessary to use various wedges or linings to align the spatial position. These wedges may fall out due to improper fixation or due to other reasons, the floors begin to sag and creak. It is impossible to eliminate such problems without dismantling some of the coatings, and dismantling is associated with large losses of time and money.

Do-it-yourself adjustable floors - a diagram of one of the possible options

Adjustable floors allow you to perfectly level surfaces on any uneven ground. In addition, the leveling mechanism makes it possible to adjust the gap between the floor and the supporting base, and this allows you to place various engineering networks in these places.

Adjustable floors consist of plastic bolt-posts or metal studs, floor joists or plywood sheets. There are many modifications of control systems, but there are no fundamental differences between them. With the help of rotation of the threaded connection, a smooth lowering / raising of structural elements occurs, in this way it is possible to accurately set the base of the floors in the required position.

There are several types of adjustable floors, you should familiarize yourself with them in more detail.

Adjustable floor. Kinds

Table. Types and brief characteristics of adjustable floors

Types of adjustable floors	Characteristics	Illustration
With plastic adjustment mechanism	They can be sold complete with lags or separate sets. Installing factory floors is much faster, they have cut threads in the logs, there is no need to mark and drill holes. The dimensions of the log are 30 × 50 mm, the distance between the bolts is 40 centimeters. Logs are recommended to be installed in increments of 30 ÷ 40 centimeters, specific values \u200b\u200bshould be chosen taking into account the expected maximum load on the floor.
With metal adjustment mechanism	Instead of plastic joints, metal studs with nuts and washers are used. They can withstand increased loads, but working with them is somewhat more difficult.
On metal corners	Advantage - the stability of the lag increases, it is possible to create complex floor designs, taking into account the peculiarities of the layout of the rooms. The disadvantage is that the installation time is significantly increased.

Both logs and plates can be regulated. The second option is used only for soft flooring or laminate flooring, the first option can be used for all types of floor finishes.

If desired, you can make adjustable floors yourself, this option has its undeniable advantages. The main ones are significantly lower cost and the ability to select lag parameters depending on the specific features of operation. If desired, the system of adjustable floors allows for floor insulation, which is very important in conditions of high energy prices.

Installation technology of factory adjustable logs on plastic bolts

Initial data. Bearing base - concrete or cement-sand screed, a set of factory-made adjustable logs is used. Let's say right away that this is the most expensive option for adjustable floors.

Step 1. Take measurements of the room to determine the amount of lag. The floors in the bath do not have a large load, the distance between the lags can be increased to 45 centimeters.

Step 2. Beat off the distance between the lags on the screed. To do this, use a rope with blue, with its help the work will be done quickly and efficiently.

Step 3 Cut the lags to the required length. The length of the sold factory logs in most cases is four meters. Think carefully about how you need to lay out the lags to minimize waste. The distance from the cutting line to the nearest adjusting bolt must be at least ten centimeters. If the end is closer, then there are risks of cracking under loads.

Step 4 Spread the logs around the marked lines. For installation, you will need a small drill with a hammer drill, a special wrench for screwing in the bolts, a doboy to fix the dowels, a screwdriver, a chisel and a hammer.

Step 5 Set the first log in a vertical position, screw plastic bolts into the threaded hole. Place the lower ends of the bolts on a line and drill a hole in the concrete base for the dowel. The depth of the holes for the dowel should be 2÷3 centimeters greater than its length. This is due to the fact that a certain amount of concrete always remains in the hole, if you do not make a margin in length, it will prevent you from hammering the dowel completely.

Step 6 Start the dowels, but do not hammer them all the way. The dowel must not interfere with the rotation of the plastic bolts. Using a long level, set the correct position of the lag. If the lag is installed, firmly fix the dowel. Continue to install lags in turn in the marked places, constantly control their position with a level.

Such an installation algorithm is offered by manufacturers, this is what many builders do, who receive wages not from production, but by the hour. The one who works from working out does it differently. How? They take the hydro level and on two opposite walls beat off the zero level of the lag. Then they drive in carnations or dowels in these places (depending on the material used to make the walls) and pull the ropes. The ropes are stretched so that they are at the ends of the lag. If the length of the room is not more than the length of the lag, then two ropes will be needed. If the logs had to be connected, then three. The rope is pulled only after the lags are already placed at the fixation points.

Then everything is simple and fast. Each lag is installed along the rope, it should not touch it, you need to check that the gap between the rope and the lag is minimal. That's all, in this way you will be able not only to significantly increase the speed of installation of an adjustable floor, but also significantly improve its quality.

There is a direct relationship between accuracy and the number of measured planes. What is meant? It is highly likely that the position of the first lag deviated from the desired level by one millimeter. It's a little, everything is fine. But the fact is that the following checks will be done taking into account this deviation, again there is a possibility of an error in a millimeter, and so on increasing. It is for this purpose that a template is made if you need to cut off a large number of identical parts, and do not take dimensions from each finished part in turn. In this case, the rope acts as a template.

Step 7. Rebuild with a wide chisel, cut off the protruding part of the plastic bolt.

Floor on plastic bolts - check

Prices for plastic bolts

plastic bolts

Video - Adjustable floor installation technology

The main advantage of such floors is that the fastening stability is significantly increased due to the increase in the area of the lower stop. The disadvantage is that the terms increase, the inability to do the work on their own.

The lags are fixed to the U-shaped plates using self-tapping screws, the height adjustment of the lag is carried out using a series of vertically located holes on both sides of the plate.

Step 1. Using a blue rope, mark the locations of the genital lags. Calculate the required amount of material and additional structures.

Step 2. Determine the level of the floor, make marks on the walls. Arrange metal plates and logs along the lines. The width of the plates must match the lag tire. The distance between the plates depends on the parameters of the lag, forty centimeters are enough for a bath.

Step 3. Fix the plates to the concrete base with dowels. Hammer the dowels immediately to the stop, then it is very difficult to pull them up - the lag lies on top and prevents access to it. If during fixing the metal plates moved a little, it's okay. When installing the logs, slightly bend their side parts in the right direction.

Bracket fixation

Step 4 Take the first log, put its ends in the right position. In this position, attach the log to the side surfaces of the U-shaped plates, use wood screws to fix it. Now you can fix the plates located in the middle of the log. But for this, constantly check the horizontal position, the lag bends a little under its own weight. If you want to do the work faster and better, then use the ropes to set the horizontal level. How this is done is described above. Make sure that the screws do not split the logs, choose them according to size, screw them in at a slight downward slope.

Step 5 After installing all the logs, you need to cut off the protruding parts of the plates with a grinder. Doing this is quite inconvenient. But, despite the “difficult” cutting conditions, try to minimally damage the wooden logs with the disc.

Installing a lag on metal studs

Adjustable floors of this type can be made independently, we will talk about this option. Select the dimensions of the log, taking into account the characteristics of the floor and maximum loads. Zinc coated metal studs, recommended diameter 6÷8 mm. To assemble the structure, you will need studs, nuts and washers.

Step 1. Beat off parallel lines on the supporting base at a distance of 30 ÷ 50 cm. The greater the distance, the more powerful the lags you need to choose.

Step 2 Make a calculation by the number of logs, studs, washers and nuts. The recommended distance between the studs is 30 ÷ 40 centimeters. Prepare all materials, additional elements and tools for the production of work.

Step 3. Mark the holes in the lags for the studs, they should all lie on the line of symmetry. In the marked places, first drill a through hole Ø6 mm for the stud (if the diameter of the stud is different, then the hole must be drilled accordingly). On the front side of the log, drill a hole for the diameter of the washer with a pen drill. The depth of the hole should be several millimeters greater than the sum of the height of the nut and the thickness of the washer.

Step 4 Lay each lag in turn on the broken parallel lines on the concrete screed. Very carefully, in turn, for each lag, make marks for future installation sites for anchor threaded elements. Make sure that the lag does not move. For marks, use a drill or an ordinary pencil. For a drill, you need to take a drill with a victorious soldering. The places are marked - take away the log and drill holes in the concrete. The dimensions of the hole must match the dimensions of the anchors.

There is a second way to mark the holes for the anchor, it takes more time, but it completely eliminates the possibility of errors. It is done like this. First, you need to mark only the two extreme holes for the anchor, screw the studs into them on two nuts and fix the log in the desired position. Now, during further marking, the lag will not move anywhere. In this position, you can immediately drill holes for the anchor to the full depth. The work is done - the lag is removed, all the studs are screwed into place. Such a procedure will have to be performed with each lag, labor productivity decreases two times. But you yourself must make the final decision on the method of marking, taking into account the condition of the concrete base of the floor and your experience in performing this kind of work.

Step 5 Place a nut on each stud and a washer. It is advisable to immediately approximately determine the location of their location in height, this will speed up the work. Screw the studs into the anchors firmly. To do this, you can use a special locksmith fixture or other simple methods. You can buy studs that have holes at the end for a plug-in barb or a hexagon for an open-end wrench, but they cost much more than ordinary ones.

Video - How to twist hairpins

Step 6. Put the logs on the studs one by one, with a wrench of the appropriate size, by turning the lower nut to the left / right, align the position of the log. How this is done, we have already told. Keep in mind that metal nuts have a much smaller thread pitch than plastic nuts. In some cases, it will take a long time to turn, which is tiring. Moreover, the position will be uncomfortable: you will have to sit on your knees, and bring the key from below the lag.

Step 7 The lags are set - you can start fixing them. Use a washer and nut, insert them into the top hole.

Important! Tighten the top nut with great force, even a slight loosening can cause very unpleasant squeaks while walking on the floor.

Step 8 Cut off the protruding ends of the studs with a grinder. Be careful with lags, do not damage the integrity of the lumber with a saw blade.

Installing floors with leveling plywood

Such a subfloor is suitable only for laminate or soft floor coverings. For installation, you need to buy a set of factory-made elements, the work is more difficult to perform.

Step 1. Mark on the plywood sheet the installation locations of the bushings, drill holes of a given diameter. The bushings should be evenly distributed over the entire area of \u200b\u200bthe sheet, the distance between them is not more than thirty centimeters. Drill holes vertically, if the edges are at an angle, you will have to re-drill them. This takes time and significantly increases the installation time of the adjustable floor.

Photo - drilling a hole in plywood

Step 2. Insert the threaded bushings into the holes from the bottom side, fasten them with small self-tapping screws, they should not turn during the adjustment of the floor height. Manufacturers provide four places for fixing the bushings, so many are not needed, it is enough to fix it with two self-tapping screws.

Step 3. Make markings on the floor, try so that the sheets do not have to be “shredded” into small pieces. Markup is a plan for cutting sheets. It is advisable to draw it on paper, think over several options, and only then it will be possible to choose the best one from them.

Step 4 Screw in all the plastic bolts, turn the plywood sheet in the desired position. Screw in the bolts the same number of turns. After installing the first sheet of plywood, note at what level the bolts are located. In the next sheet of plywood, try to screw the bolts in the same position.

Step 5 Using a special wrench, screw in / unscrew the bolts until the plywood sheet is in a strictly horizontal position at the required height. Constantly check its position with a level in several planes. Very important! All bolts must have a slight tension, otherwise the plywood will sag. The work is quite difficult, do not make plywood sheets large. You must reach each bolt from the concrete floor. It is very difficult to adjust the position of the plywood sheet and at the same time be on it.

Keep in mind that the fasteners to the concrete base are not fixed, the floor turns out to be “floating”. This factor should be taken into account when deciding on the arrangement of floor coverings in each particular room.

Step 6 After installing the last plywood sheet, check the position of the subfloor again. Remember that the adjustment parameters do not exceed 2÷3 centimeters. If the concrete base has too large irregularities, then you will have to level it first. Plywood should only be waterproof.

Do not use chipboard, OSB, or other materials in place of heavy-duty plywood, although some manufacturers recommend such. Pressed materials react very poorly to point multidirectional forces, in these places they quickly lose their original bearing capacity. Namely, such loads are present in the places of adjustment of the plates. Let plywood cost much more, its price will pay off during the operation of the floor.

Name	The size	Variety	price, rub.
Plywood FC unsanded	4x1525x1525 mm	4/4	RUB 247.00/piece
Plywood FC unsanded	6x1525x1525 mm	4/4	RUB 318.00/piece
Plywood FC unsanded	8x1525x1525 mm	4/4	RUB 448.00/piece
Plywood FC unsanded	10x1525x1525 mm	4/4	RUB 560.00/piece
Plywood FC unsanded	15x1525x1525 mm	4/4	RUB 738.00/piece
Plywood FSF unsanded	9x1220x2440mm	3/3	RUB 1,048.00/piece
Plywood FSF unsanded	12x1220x2440mm	3/3	RUB 1,345.00/piece

Prices for anchors for sheet materials

anchors for sheet materials

Do not forget to leave gaps 1÷2 centimeters wide around the perimeter of the room near the walls for natural ventilation and compensation for the expansion of wooden structures. These gaps are then closed with skirting boards and become invisible.
For logs, choose only high-quality lumber with a minimum number of knots. Large cracks, visible fungal diseases and mold infestations are not allowed.
Do not drill holes for studs on knots, it is better to move them a few centimeters. The fact is that wood in the event of a violation of the integrity of a healthy knot significantly loses its strength. The device of adjustable floors assumes the presence of efforts not over the entire area of \u200b\u200bthe log, but only at several points. This feature requires increased strength indicators from wood. This remark also applies to the bearing base of the floor, point forces also act on it, the load per square millimeter increases significantly. Accordingly, concrete must be strong, it is not allowed to deviate from existing building standards during its manufacture. Any deviations in strength will lead to the fact that over time, under the stops, the base will be destroyed, the floors will begin to sag and, as a result, it is very unpleasant to creak. It is impossible to eliminate these sounds without dismantling the entire structure.
The higher the level of the adjustable floor above the ceiling, the more it "sounds". To reduce the noise level, it is recommended to use pressed mineral wool. At the same time, it will insulate the floor.

And the main advice in conclusion. Use adjustable floor options only as a last resort. Practice shows that the number of disadvantages of such structures exceeds the number of advantages. The cost of only adjustable logs can exceed the total cost of flooring made in the usual traditional way. Decide what to do faster: immediately put a few lags or drill dozens of holes in them and then “screw” them in the sweat of your brow with bolts and nuts.

Video - How to make an adjustable floor

Usually this:

voltage of the required value and sign;
output voltage ripple coefficient corresponding to certain frequencies;
the presence or absence of stabilization of the output voltage;
rated and maximum load current;
overload and short circuit protection.

general description

The peculiarity of the power supply unit (PSU) is that it is made as a separate external node. A laboratory PSU is a case with a front panel, regulators, switches, a voltmeter, an ammeter, output terminals and a power cord. Next, we will tell our readers about what needs to be considered when making an adjustable power supply on your own and how to get the best result at minimal cost.

To begin with, let us dwell on a broader interpretation of the criteria listed above. We start from the list and consider the voltage of the required magnitude and sign. This is the most important point, which generally determines the circuit and design of the power supply. The first thing to consider is compliance with the tasks to be solved. Their number is always limited by the power of the PSU and, as a result, the quality of the output voltage.

Output voltage ripple is an undesirable parameter that consists of a low frequency component that is a multiple of the supply voltage frequency and additional higher frequencies. To influence this parameter in one way or another in a wide range of frequencies, you will need an oscilloscope. Otherwise, it will be difficult to evaluate.

Stabilization of the output voltage is the most important characteristic of the power supply. It reduces low-frequency ripple to a minimum and improves the quality of the load. Since the stabilizer contains a controlled element, it becomes possible to control the output voltage.

Maximum currents determine the consumer properties of the PSU. The larger they are, the wider the scope of the PSU. Additionally, voltages can be mentioned. The voltage drop on the controlled element of the stabilizer leads to its heating and limits the scope of the PSU. Therefore, subranges of voltage are needed, which is supplied to the input of the stabilizer. Switching between them allows you to reduce the heating of the controlled element of the stabilizer at the required output voltage.

Overload and short circuit protection protects the controlled element from being damaged by an unacceptably large current.

Two concepts

For the safe operation of any electrical equipment with which a person is in direct contact, reliable isolation from the 220 V supply network is necessary. The best solution to this problem is the use of a transformer. The current state of the art provides solutions from which to choose. For example, a transformer might be:

or as an independent unit and is made on a steel core as a standard transformer (ST) with a primary winding directly connected to the mains;
or as part of an inverter circuit as a pulse transformer (IT).

Consider the consumer properties of both options. Let's start with irresistible characteristics. For ST, these are dimensions and weight. They cannot be changed because they are linked together with the electrical power corresponding to the frequency of 50 Hz of the 220 V network. For IT, this is electromagnetic interference. If it is planned to supply power to sensitive amplifiers or radio circuits, the power supply will certainly introduce interference that will spoil something, superimposed on the useful signal. But if the listed tasks are not planned, you can take one of the standard power supplies for a computer as a basis.

computer block

In such a solution, the good side is to obtain several stabilized voltages at a power that can be chosen. Its value is standardized and ranges from 60 to 1700 watts. But you can find a more powerful unit. Accordingly, its price will be about $500. But the result is several computer-standard voltages: 3.3 V, 5 V, and 12 V, and high currents of 20 A or more. All of them are tied to a common wire. Therefore, they cannot be connected in series in order to obtain a higher total voltage.

Another inconvenience of a computer PSU is its inability to work reliably with a rapidly changing load. It is designed to power the computer's memory, processor, and disk devices. That is, when you turn it on, it immediately loads almost at full capacity. It changes only as the processor is loaded, but not significantly. In order to work with such a power supply without hassle, it must be minimally loaded onto a 5 V output resistor. To do this, you can use home-made nichrome spirals. The resistance value is determined experimentally by selection based on approximately 0.12 PSU power and a voltage of 5 V.

If the current is too low, the power supply inverter will not work, and there will be no voltage on the selected resistor. Each of the voltages of 3.3 V, 5 V and 12 V can only be regulated by an additional stabilizer. Otherwise, you need to open the block and make changes to its scheme. The most economical solution for a controlled element is a pass transistor. This means that at the output of each channel after the stabilizer, the continuously adjustable voltage will correspond to approximately 2.3 V, 4 V and 8 V or less. Depending on how the voltage regulator is configured.

Choosing a scheme

PSU is best made on the basis of specialized microcircuits 142EN3, 142EN4, 1145EN3, K142EN3A, K142EN3B, K142EN4A, K142EN4B, KR142EN3 or similar:

For our PSU, we use the 142EN3 chip. She has the following main parameters:

The voltage at the input of the stabilizer is set by a variable resistor R1.

But to work with high load currents, one or more power transistors are introduced into the circuit. This is shown in the following images:

For proper operation, the microcircuit is powered from a 12 V channel. The collector of each transistor is connected to one of the output channels of a computer PSU. The option with several transistors provides a rated load current of 20 A. Additional transistors are selected according to the power of the computer PSU. As a result, we obtain the general scheme of an adjustable power supply:

Transistors and a microcircuit must be placed on a common radiator.

Transistors will heat up the more, the lower the output voltage. Therefore, it is necessary to place the microcircuit as close as possible to the transistor. The operation of the thermal protection in it to avoid thermal damage to the transistors. Such a power supply can be used to charge a car battery and other purposes that correspond to the voltage range from 0 to 12 volts.

To use each channel to the maximum voltage, you need to make a special switch for two positions (not shown in the diagrams). Its task is to connect the output terminal of the channel directly, bypassing the stabilizer.

If you need to get a higher voltage, the easiest way is to duplicate the mentioned device. As a result, you can get several combinations of output parameters:

bipolar power supply 12 V;
unipolar power supply 3.7V, 8.7V, 12V, 15.3V, 17V and 24V.

All of these modes can be obtained in one PSU by the corresponding position of the switches. To regulate the voltage in each leg of a bipolar 12 V power supply, a dual regulator is required. Its diagram is shown below in the image. A unipolar power supply does not need a second regulator. The voltage regulator chip allows you to use another computer PSU and thereby achieve a voltage of 36 V.

A unipolar power supply, assembled on the basis of two or three computer power supplies, uses one stabilizer and an additional switch. It switches the channels of computer power supplies and generates one or another subrange voltage at the input of the stabilizer. Because this adds complexity to the circuit, this option is not shown.

Conclusion

It should be noted that two computer power supplies will double the power, and three will triple. At the same time, in comparison with the transformer version (on a steel core), the resulting design will be more compact and lighter. The reason for this is that thousands of microfarads of electrolytic capacitors are required to achieve efficient filtering of the low side voltage of the rectifier at 50 Hz. If you repeat all 6–9 voltage channels, which are obtained using two or three computer PSUs, the dimensions of the ST variant will turn out to be noticeably larger.

It is important to take into account several types of protection already built into a computer PSU. Otherwise, they will either have to be additionally manufactured, or without them a less reliable unit will turn out.

Also, it will not be possible to achieve the current strength characteristic of a computer PSU. Therefore, we recommend that you opt for the proposed adjustable power supply. Since its circuit is simple, it can be assembled by surface mounting. The support mounting pads are placed on the transistor heatsink. The case and design of the PSU can be varied. It depends on the choice of heatsinks, switches, ammeter and voltmeter. Since only a craftsman with a certain experience can make such a device with his own hands, it makes no sense to impose a dissenting opinion.

From the article you will learn how to make a do-it-yourself adjustable power supply from available materials. It can be used to power household equipment, as well as for the needs of your own laboratory. A DC voltage source can be used to test devices such as a car alternator relay-regulator. After all, when diagnosing it, there is a need for two voltages - 12 Volts and over 16. Now consider the design features of the power supply.

Transformer

If the device is not planned to be used for charging acid batteries and powering powerful equipment, then there is no need to use large transformers. It is enough to apply models whose power is not more than 50 watts. True, in order to make an adjustable power supply with your own hands, you will need to slightly change the design of the converter. First of all, you need to decide what range of voltage change will be at the output. The characteristics of the power supply transformer depend on this parameter.

Let's say you have chosen the range of 0-20 Volts, which means that you need to build on these values. The secondary winding should have an alternating voltage of 20-22 Volts at the output. Therefore, you leave the primary winding on the transformer, and wind the secondary winding on top of it. To calculate the required number of turns, measure the voltage, which is obtained from ten. A tenth of this value is the voltage obtained from one turn. After the secondary winding is done, it is necessary to assemble and tie the core.

Rectifier

As a rectifier, you can use both assemblies and individual diodes. Before you make an adjustable power supply, select all its components. If the output is high, then you will need to use powerful semiconductors. It is advisable to install them on aluminum radiators. As for the circuit, only the bridge circuit should be preferred, since it has a much higher efficiency, less voltage loss during rectification. It is not recommended to use a half-wave circuit, since it is inefficient, there are many ripples at the output that distort the signal and are a source of interference for radio equipment .

Stabilization and adjustment block

For the manufacture of the stabilizer, it is most reasonable to use the LM317 microassembly. A cheap and affordable device for everyone, which will allow you to assemble a high-quality do-it-yourself power supply in a matter of minutes. But its application requires one important detail - effective cooling. And not only passive in the form of radiators. The fact is that voltage regulation and stabilization occur according to a very interesting scheme. The device leaves exactly the voltage that is needed, but the excess entering its input is converted into heat. Therefore, without cooling, the microassembly is unlikely to work for a long time.

Take a look at the diagram, there is nothing super complicated in it. The assembly has only three outputs, the third is energized, the second is removed, and the first is necessary to connect to the minus of the power supply. But here a small feature arises - if you turn on resistance between the minus and the first output of the assembly, then it becomes possible to adjust the voltage at the output. Moreover, a do-it-yourself power supply can change the output voltage both smoothly and in steps. But the first type of adjustment is the most convenient, so it is used more often. For implementation, it is necessary to include a variable resistance of 5 kOhm. In addition, a constant resistor with a resistance of about 500 ohms is required between the first and second output of the assembly.

Current and voltage control unit

Of course, in order for the operation of the device to be as convenient as possible, it is necessary to control the output characteristics - voltage and current. A circuit of an adjustable power supply is being built in such a way that the ammeter is connected to the break in the positive wire, and the voltmeter is connected between the outputs of the device. But the question is different - what type of measuring instruments to use? The easiest option is to install two LED displays, to which you can connect a volt- and ammeter circuit assembled on a single microcontroller.

But you can mount a couple of cheap Chinese multimeters in an adjustable power supply, made with your own hands. Fortunately, they can be powered directly from the device. You can, of course, use dial indicators, only in this case it is necessary to calibrate the scale for

Device body

The case is best made of light but durable metal. Aluminum would be ideal. As already mentioned, the regulated power supply circuit contains elements that get very hot. Therefore, a radiator must be mounted inside the case, which can be connected to one of the walls for greater efficiency. It is desirable to have a forced airflow. For this purpose, you can use a thermal switch paired with a fan. They must be installed directly on the cooling radiator.

The master, whose device description is in the first part, having set himself the goal of making an adjustable power supply, did not complicate his business and simply used boards that were idle. The second option involves the use of even more common material - an adjustment was added to the conventional unit, perhaps this is a very promising solution in terms of simplicity, despite the fact that the necessary characteristics will not be lost and even the most experienced radio amateur can implement the idea with his own hands. As a bonus, two more options for very simple schemes with all the detailed explanations for beginners. So there are 4 options for you to choose from.

We will tell you how to make an adjustable power supply from an unnecessary computer board. The master took the computer board and sawed out the block that feeds the RAM.
This is how he looks.

Let's decide which parts need to be taken, which ones are not, in order to cut off what is needed so that all the components of the power supply are on the board. Usually, a pulse unit for supplying current to a computer consists of a microcircuit, a PWM controller, key transistors, an output inductor and an output capacitor, an input capacitor. For some reason, there is also an input choke on the board. Left him too. Key transistors - maybe two, three. There is a seat for 3 transistors, but it is not used in the circuit.

The PWM controller chip itself may look like this. Here she is under a magnifying glass.

It may look like a square with small leads on all sides. This is a typical PWM controller on a laptop board.

It looks like a switching power supply on a video card.

The power supply for the processor looks exactly the same. We see a PWM controller and several processor power channels. 3 transistors in this case. Throttle and capacitor. This is one channel.
Three transistors, inductor, capacitor - the second channel. 3 channel. And two more channels for other purposes.
You know what a PWM controller looks like, look at its marking under a magnifying glass, search the Internet for a datasheet, download a pdf file and look at the diagram so as not to confuse anything.
In the diagram we see a PWM controller, but the conclusions are marked along the edges, numbered.

transistors are labeled. This is a choke. This is an output capacitor and an input capacitor. The input voltage ranges from 1.5 to 19 volts, but the voltage supply to the PWM controller should be from 5 volts to 12 volts. That is, it may turn out that a separate power supply is required to power the PWM controller. All wiring, resistors and capacitors, do not be alarmed. You don't need to know. Everything is on the board, you do not assemble a PWM controller, but use a ready-made one. You only need to know 2 resistors - they set the output voltage.

resistor divider. Its whole essence is to reduce the signal from the output to about 1 volt and apply feedback to the input of the PWM controller. In short, by changing the value of the resistors, we can adjust the output voltage. In the case shown, instead of the feedback resistor, the master put a 10 kilo-ohm tuning resistor. This proved to be sufficient to regulate the output voltage from 1 volt to about 12 volts. Unfortunately, this is not possible on all PWM controllers. For example, on our controllers for processors and video cards, in order to be able to adjust the voltage, the possibility of overclocking, the output voltage is supplied programmatically via a multi-channel bus. You can change the output voltage of such a PWM controller only with jumpers.

So, knowing what the PWM controller looks like, the elements that are needed, we can already cut out the power supply. But you need to do this carefully, since there are tracks around the PWM controller that you may need. For example, you can see - the track goes from the base of the transistor to the PWM controller. It was difficult to save it, I had to carefully cut out the board.

Using the tester in continuity mode and focusing on the circuit, I soldered the wires. Also using the tester, I found the 6th output of the PWM controller and the feedback resistors rang from it. The resistor was rfb, it was soldered out and instead of it, a 10 kilo-ohm trimming resistor was soldered from the output to regulate the output voltage, I also found out by calling that the power of the PWM controller is directly connected to the input power line. This means that it will not be possible to apply more than 12 volts to the input, so as not to burn the PWM controller.

Let's see how the power supply looks like in operation

Soldered the plug for the input voltage, voltage indicator and output wires. We connect an external power supply of 12 volts. The indicator lights up. Already set to 9.2 volts. Let's try to adjust the power supply with a screwdriver.

It's time to check out what the power supply is capable of. I took a wooden block and a homemade wire resistor made of nichrome wire. Its resistance is low and, together with the tester probes, is 1.7 ohms. We turn on the multimeter in ammeter mode, connect it in series with the resistor. See what happens - the resistor glows red, the output voltage barely changes, and the current is about 4 amps.

Previously, the master has already made similar power supplies. One is cut out by hand from the laptop board.

This is the so-called duty voltage. Two sources for 3.3 volts and 5 volts. Made him a case on a 3d printer. You can also see an article where I made a similar adjustable power supply, also cut it out of a laptop board (https://electro-repair.livejournal.com/3645.html). This is also a PWM RAM power controller.

How to make a regulating PSU from a regular one, from a printer

We will talk about the canon printer power supply, inkjet. They are left unused for a lot of people. This is essentially a separate device, the printer is held on by a latch.
Its characteristics: 24 volts, 0.7 amperes.

I needed a power supply for a homemade drill. It's just right for the power. But there is one caveat - if you connect it like that, we get only 7 volts at the output. Triple output, connector and we get only 7 volts. How to get 24 volts?
How to get 24 volts without disassembling the block?
Well, the simplest is to close the plus with an average output and get 24 volts.
Let's try to do it. We connect the power supply to the network 220. We take the device and try to measure it. Connect and see the output of 7 volts.
It does not have a central connector. If we take and connect to two at the same time, we see a voltage of 24 volts. This is the easiest way to make sure that this power supply, without disassembling, gives out 24 volts.

A homemade regulator is needed so that the voltage can be regulated within certain limits. 10 volts to max. This is easy to do. What is needed for this? First, open the power supply itself. It is usually glued on. How to open it so as not to damage the case. You don't have to poke or poke anything. We take a piece of wood more massive or there is a rubber mallet. We put it on a hard surface and peel along the seam. The glue comes off. Then they sounded good on all sides. Miraculously, the glue comes off and everything opens up. Inside we see the power supply.

We'll get paid. Such power supplies are easy to convert to the desired voltage and can also be made adjustable. On the reverse side, if we turn it over, there is an adjustable zener diode tl431. On the other hand, we will see the middle contact goes to the base of the q51 transistor.

If we apply voltage, then this transistor opens and 2.5 volts appear on the resistive divider, which are necessary for the operation of the zener diode. And the output appears 24 volts. This is the easiest option. How to start it, you can still - is to throw out the transistor q51 and put a jumper instead of the resistor r 57 and that's it. When we turn it on, the output is always 24 volts continuously.

How to make an adjustment?

You can change the voltage, make it 12 volts. But in particular the master, it is not necessary. It needs to be adjustable. How to do? We discard this transistor and instead of a 57 by 38 kilo-ohm resistor we put an adjustable one. There is an old Soviet one for 3.3 kilo-ohms. You can put from 4.7 to 10, which is. Only the minimum voltage to which it can lower it depends on this resistor. 3.3 is very low and not needed. The motors are planned to be supplied at 24 volts. And just from 10 volts to 24 is normal. Who needs a different voltage, you can use a large resistance trimmer.
Let's go, let's drink. We take a soldering iron, hair dryer. Soldered the transistor and resistor.

Soldered a variable resistor and try to turn it on. I applied 220 volts, we see 7 volts on our device and we begin to rotate the variable resistor. The voltage has risen to 24 volts and smoothly rotate, it drops - 17-15-14, that is, it drops to 7 volts. In particular, it is installed at 3.3 room. And our change turned out to be quite successful. That is, for purposes from 7 to 24 volts, voltage regulation is quite acceptable.

Such an option turned out. Installed a variable resistor. The handle turned out to be an adjustable power supply - quite convenient.

Video channel "Tekhnar".

It is easy to find such power supplies in China. I came across an interesting store that sells used power supplies from various printers, laptops and netbooks. They disassemble and sell the boards themselves, fully serviceable for different voltages and currents. The biggest plus is that they dismantle branded equipment and all power supplies are of high quality, with good details, all have filters.
Photos - different power supplies, cost a penny, almost a freebie.

Simple block with adjustment

A simple version of a home-made device for powering devices with regulation. The scheme is popular, it is distributed on the Internet and has shown its effectiveness. But there are also limitations, which are shown on the video along with all the instructions for making a regulated power supply.

Homemade regulated block on one transistor

What is the simplest regulated power supply you can make yourself? This can be done on the lm317 chip. She already with herself is almost a power supply. On it, you can make both a voltage-adjustable power supply and a flow. This video tutorial shows a device with voltage regulation. The master found a simple scheme. Input voltage maximum 40 volts. Output from 1.2 to 37 volts. Maximum output current 1.5 amps.

Without a heat sink, without a radiator, the maximum power can be only 1 watt. And with a 10 watt heatsink. List of radio components.

Let's start assembling

Connect an electronic load to the output of the device. Let's see how well it holds current. Set to the minimum. 7.7 volts, 30 milliamps.

Everything is regulated. We set 3 volts and add current. On the power supply, we will set the restrictions only more. Move the toggle switch to the top position. Now 0.5 amps. The microcircuit began to warm up. Nothing to do without a heat sink. I found some kind of plate, not for long, but enough. Let's try again. There is a drawdown. But the block works. Voltage regulation is in progress. We can insert a credit for this scheme.

Radioblog video. Solderer video blog.