How to make a USB fan using improvised materials. Low noise fan How to make a small fan with your own hands

Very often, in the sultry heat, there is not enough air flow in the room. To solve this problem, many people buy table fans; they are convenient and compact, some of them work from USB, that is, they can be connected to any charger, power bank or laptop, so that the coolness is always with you. But why buy something that you can make yourself using available materials? For site readers we have prepared two simple instructions who will clearly explain how to do USB fan at home with your own hands. So, all you need to prepare is a sharp knife, good scissors, electrical tape, an unnecessary USB cord and, in fact, a homemade executive body. As for the latter, it is customary to use one of two options: an old cooler from a computer or a motor from a car or other toy.

Idea No. 1 – Use a cooler

It will take no more than 15 minutes to assemble a USB fan from a cooler. First you need to prepare the cooler. Two wires come out of the device - black and red, and sometimes yellow, even less often - blue. Yellow and blue are of no use to us. We strip the insulation by 10 mm and put the prepared element aside.

Next you need to prepare the USB cable. We cut off one half of it and clean off the insulation at the cut site with a sharp knife; a stationery knife works perfectly. Under it you will see four wires, of which two are necessary: ​​red and black. We also clean them, but it is better to cut off the other two (usually green and white) and insulate them.

Now, as you understand, you need to connect the prepared contacts in pairs, according to: red to red, black to black using twisting. After this, you need to carefully insulate the cable connections using electrical tape or heat shrink and make a stand. As for the stand, it’s up to your imagination. Some people successfully use wire, while others cut out a nest in a cardboard box in a very interesting way.

In the end, a homemade mini fan is connected to a computer or charging unit, and you can enjoy the operation of your own electrical appliance.

Cooler idea

Idea No. 2 – Use a motor

In order to make a USB fan from a motor and a CD, it will take a little more time, but you can still easily make such an electrical device with your own hands in an hour. A motor for such a homemade product should be chosen with an operating voltage of approximately 5 Volts, maybe a little more. If you take the motor to a lower voltage, too much current will flow through the circuit and the motor will quickly fail.

First, we prepare all the elements of the device. In this case, you will need to make an impeller (blades).

To do this, we recommend using an ordinary CD. Let's line it up by 8 equal parts and carefully cut through with good scissors, almost reaching the center. Next, we heat the disk (it’s convenient to do this with a lighter), and when the plastic becomes more elastic, we bend the blades at an equal angle (as shown in the photo).

If the impeller is not bent enough, then no air flow will be created during the rotation of the disk. However, if you overdo it, the homemade product will also work poorly and unstable.

When the blades are ready, move on to creating the main mechanism. Inside the disk you need to insert an ordinary champagne cork, cut to the required size, which must be placed on the motor shaft. Next, we move on to creating a USB fan stand for a laptop.

Here, as in the previous version, everything depends on your imagination. Of all the available means, the option with wire is the most suitable. When homemade USB the fan is ready, we connect the motor wires to the USB cord wires, as in the previous version, carefully isolate the twist and proceed to testing.

Creating air flow with high density possible in several ways. One of the effective ones is a radial type fan or “snail”. It differs from others not only in shape, but also in its operating principle.

Fan device and design

Sometimes an impeller and a power unit are not enough to move air. In conditions of limited space, a special type of exhaust equipment design should be used. It has a spiral-shaped body that acts as an air channel. You can make it yourself or purchase it already finished model.

To form a flow, the design provides a radial impeller. It connects to the power unit. The wheel blades have a curved shape and create a discharged area when moving. Air (or gas) enters it from the inlet pipe. When moving along the spiral body, the speed at the outlet increases.

Depending on the application centrifugal fan snail maybe general purpose, heat-resistant or corrosion-resistant. It is also necessary to take into account the amount of air flow created:

• low pressure. Scope of application: production workshops, household appliances. The air temperature should not exceed +80°C. Mandatory absence of aggressive environments;
• average pressure value. It is part of exhaust equipment for removing or transporting small fraction materials, sawdust, grain;
• high pressure. Forms an air flow into the fuel combustion zone. Installed in many types of boilers.

The direction of movement of the blades is determined by the design, and, in particular, by the location of the outlet pipe. If it is located on the left side, the rotor should rotate clockwise. The number of blades and their curvature are also taken into account.

For powerful models You need to make a reliable base with your own hands to secure the body. The industrial installation will vibrate strongly, which may lead to its gradual destruction.

Self-production

First of all, you need to decide functional purpose centrifugal fan. If it is necessary for ventilation of a certain part of the room or equipment, the housing can be made from scrap materials. To complete the boiler, you will need to use heat-resistant steel or make it from stainless steel sheets yourself.

First, the power is calculated and the set of components is determined. The best option The snail will be dismantled from old equipment - an extractor hood or a vacuum cleaner. The advantage of this manufacturing method is the exact match between the power of the power unit and the body parameters. A snail fan can be easily made with your own hands only for some applied purposes in a small home workshop. In other cases, it is recommended to purchase a ready-made model industrial type or take the old one from the car.

Procedure to make a centrifugal fan with your own hands.

1. Calculation overall dimensions. If the device will be installed in a confined space, special damper pads are provided to compensate for vibration.
2. Manufacturing of the body. In the absence of finished design You can use plastic sheets, steel or plywood. In the latter case special attention is given to sealing joints.
3. Installation diagram of the power unit. It rotates the blades, so you need to choose the type of drive. For small designs, a shaft is used to connect the motor gearbox to the rotor. In powerful installations, a belt type drive is used.
4. Fastening elements. If the fan is installed on the outer casing of, for example, a boiler, mounting U-shaped plates are made. With significant power, it will be necessary to make a reliable and massive base.

This general scheme, which can be used to make a functional exhaust centrifugal unit with your own hands. It may change depending on the availability of components. It is important to comply with the requirements for sealing the housing, as well as to ensure reliable protection of the power unit from possible clogging with dust and debris.

The fan will make a lot of noise during operation. Reducing this will be problematic, since vibration of the housing during the movement of air flows is almost impossible to compensate with your own hands. This is especially true for models made of metal and plastic. Wood can partially reduce background noise, but at the same time it has a short service life.

In the video you can see the process of manufacturing a case from PVC sheets:

Review and comparison of production ready models

Considering radial fan snail, it is necessary to take into account the material of manufacture: cast aluminum body, sheet or stainless steel. A model is selected based on specific needs; consider an example of serial models in a cast case.

Throughout the long winter, we look forward to pleasant summer days, and with the onset of hot weather, for some reason we begin to dream of coolness. How delightfully a light breeze created by a small homemade fan will help restore strength and relieve fatigue. Plus, making it is incredibly fun, right?

We invite you to familiarize yourself with step by step instructions on assembling protozoa effective devices from literally waste raw materials. The article presented to your attention describes in detail how to make a fan with your own hands and what a home craftsman will need for this.

At your disposal is a detailed description of the manufacture of options, the effects of which have been tested in practice. You can make such devices yourself without having any experience at all. For a complete understanding of the information, attached step by step photos and video instructions.

The simplest fan can be made from CD discs. It can be used, for example, for local impact on a user who spends a long time at the computer.

Let's prepare starting materials to do the job:

• CD discs – 2 pcs.;
• low-power motor;
• wine bottle cork;
• cable with USB plug;
• a tube or rectangle made of thick cardboard;
• soldering iron;
• candle or lighter, hot glue;
• pencil, ruler, squared paper.

For our purposes, you can use a motor from an old toy, for example, from a toy car. A toilet paper roll slightly decorated with decorative finishing paper can be used as a cardboard tube.

The main advantage of this model is that almost any do-it-yourself enthusiast will have all the materials necessary for its manufacture.

The assembly process of the mini fan is quite simple.

Let's take one of the CDs and use a marker to divide its surface into eight identical sections. The easiest way to do this is to use a sheet of checkered paper.

Draw a cross on it from a horizontal and vertical line. We divide each of the four resulting right angles in half. Using cells, this is not difficult to do.

Using a very simple method using a checkered piece of paper, we can achieve the perfect layout of the disk into eight equal sectors

We place a disk on our drawing so that the intersecting lines are in the very center of its hole. Alternately applying a ruler to the lines diverging from the center, we make markings on the disk. This way the sections will be the same.

To divide the disk into blades, follow the marking lines with a soldering iron from the transparent part to the edge.

You can also use scissors for cutting, but there is a danger that the workpiece will crack during the process. If you don’t have a soldering iron, you need to use a knife preheated on the stove. When working with a soldering iron, deposited plastic is formed along the edges of the cut, which can be easily removed with a knife.

Cutting a disk with a soldering iron is the most effective method, in which the workpiece will not crack or deform, and the remnants of the deposited plastic can be easily removed with a knife

We heat the surface of the disk over the flame of a burning candle so that the blades can be slightly turned. If you don't have a candle, a lighter or a soldering iron will do.

The central part of the disk should be heated, and all blades should be turned in the same direction. Place in the disc hole wine cork. To fix it better, you need to pre-treat the edges of the hole with hot glue.

The USB cable must be connected to the motor. If we don’t guess the direction of rotation of the propeller, we can swap the reins, that is, change the polarity.

The motor needs to be glued to a cardboard tube, and the tube itself to a second CD, which will act as the base of the stand.

When the plug is installed in the hole, the stand from the second CD and cardboard tube, as well as the connecting device are already assembled, it is very important to correctly fit the propeller onto the motor shaft

Now the propeller needs to be “planted” on the rod of the future fan. We will try to make sure that it is installed strictly in the center. You can secure it in this position using hot glue.

After all work is completed, the fan is ready for use.

Although the construction of this device will not take you much time, the result of the work performed will undoubtedly please you

How to make something similar, but a little more complex design Having included a regulator in the circuit, look at the video posted at the end of this article.

Do you find these homemade instructions complicated? Then you may be interested in information about and rules for choosing them in order to purchase a ready-made device offered by household appliance manufacturers.

Fan based on a plastic bottle

What our craftsmen don’t do from plastic bottles! The time has come to say that they also make a very good fan. It may not ventilate your entire room, but it will definitely help those who have to work at a computer.

We offer two options for creating such a fan model.

Option #1 – hard plastic model

To complete the work we will need:

• plastic bottle with a capacity of 1.5 liters;
• a motor from an old toy;
• small switch;
• Duracell battery;
• marker;
• scissors;
• candle;
• hammer and nail;
• foam;
• hot glue gun.

So, let's take the ordinary one plastic bottle 1.5 liters with plug. At the level of the label line, cut it off top part. This is exactly what we need to make the propeller. We divide the surface of the plastic blank into six parts.

We try to mark it out so that we get equal sectors: the quality of operation of the future device depends on this.

We cut the workpiece along the markings almost to the neck. We bend the blades of the future propeller and cut off every second of them. We are left with a blank with three blades equidistant from each other. The edges of each blade must be rounded. We do this carefully.

To remove those parts of the blades that are closer to the neck of the workpiece, it is better to use a utility knife; do not forget to round the edges of the blades

Now we will need a small candle. Let's light it up. We heat each blade at the base on it to turn it in the direction we need. All blades must be turned in the same direction. Remove the lid from the workpiece and punch a hole in the very center using a nail and hammer.

We place the plug on the rod of a small motor. Such motors can remain from old children's toys. As a rule, getting them is not difficult. Secure the cork with glue.

Now you need to make a base on which the motor will rest. For this purpose, we take, for example, a piece of polystyrene foam. We attach a rectangle to it, which can also be cut out of foam packaging.

Our motor, to which the propeller is attached, will be fixed on the upper surface of this rectangle. To do this, you need to make a recess in the foam that corresponds to the parameters of the motor.

Hot melt adhesive is used to secure the elements of the product. If it is unavailable, other adhesives can be used. It is important that the fastening itself is as reliable as possible.

Let's make a simple fan.
You will need:
1. 3V motor
2. Section for 2 batteries of 1.5 V each. I bought it from the CHIP and DIP store.
3. Switch.
4. Wire 15 cm.
5. Reels from fishing line or ropes, a jar from Polysorb, a jar of gouache.
6. Impeller from the power supply cooler.
7. Soldering iron.
8. Thermal gun.
9. Self-tapping screws 11 pcs. 2 cm long.

1. Take spools of thread with a diameter of 5 mm and a height of 4.5 cm - from fishing line or cord.
Mark a hole for the switch with a marker and cut it nail scissors the hole is slightly smaller than the size of the switch and insert the switch into the reel:

2. Now we form the fan frame: put 3 bobbins together and mark four holes for bolts or screws with a marker on the bottom of the upper bobbins. We burn holes through the edges of two bobbins:

3. Using a lighter, melt and clear the red wire from the section with batteries and attach it to one terminal of the switch, and to the other - the second red wire. To isolate the terminals from contact with each other, fill them with hot glue:

4. We attach the red wire to the plus + of the engine, and the black wire, respectively, to the minus - of the engine:

5. The top can be made from a gouache box: on the lid with a soldering iron we form a hole for the wires and 3 holes for the screws. And on the box itself we cut a hole with nail scissors slightly smaller than the diameter of the engine and place it inside. As in the case of the switch, you can pour hot glue on the outside for reliability.

6. We place the impeller from the cooler on the plug, fill the voids with plasticine or fill it with paraffin, use a screw or an awl to make a hole in the plug, fill it epoxy glue or hot glue, and place it on the engine. If it is epoxy resin, leave it to dry for a day and only then turn it on!

The question is trivial. First, we recommend determining where to install your homemade fan. Two types of engines dominate in technology: commutator (historically the first), asynchronous (invented by Nikola Tesla). The first ones make a lot of noise, switching sections causes a spark, the brushes rub, causing noise. An asynchronous motor with a squirrel-cage rotor is quieter and generates less interference. You will find the start-up protection relay in the refrigerator. By adding a couple of phrases of humorous phrases, we will return the seriousness of the site. How to make a fan with your own hands without scaring your family. Let's try to answer.

Aspects of designing a homemade fan

The design of the fan is so simple that there is no point in telling or describing the insides. What to consider when designing? Remember the growl cyclone vacuum cleaner, volume above 70 dB. Inside brushed motor. Often deprived of the ability to regulate speed. Decide, is a similar sound pressure level acceptable at the installation site of a homemade fan? Having chosen the second, we will concentrate on asynchronous motors; simple models do not require a starting winding. The power is low, the secondary EMF is induced by the stator field.

The drum of an asynchronous motor with a squirrel-cage rotor is cut with copper conductors along the generatrix, at an angle to the axis. The direction of the slope determines the direction of rotation of the engine rotor. Copper conductors are not insulated from the drum material; the conductivity of Olympic metal is superior surrounding material(silumin), the potential difference between adjacent conductors is small. Current flows through copper. There is no contact between the stator and rotor, the spark has nowhere to come from (the wire is covered with varnish insulation).

The noise of an asynchronous motor is determined by two factors:

1. Alignment of stator and rotor.
2. Bearing quality.

By correctly setting up and servicing an asynchronous motor, you can achieve almost complete noiselessness. We recommend considering whether sound pressure level is important. The case concerns a duct fan - it is allowed to use a commutator motor, the requirements will be determined by the location of the section.

The duct fan is placed inside the air duct section and mounted, breaking the duct. The section is removed for maintenance.

Noise loses its dominant role. sound wave, passing through the air duct, it is attenuated. Particularly fast is the part of the spectrum that has inconsistent dimensions relative to the width/length of the path section. Read more textbooks on acoustic lines. The brushed motor can be used in a basement, garage, or unoccupied areas. The neighbors of the cooperative will hear, but will rather be too lazy to pay attention.

What is good about a commutator engine, what are we fighting for the right to use. Three disadvantages of asynchronous:

At the initial moment asynchronous motor does not develop high torque, a number of special design measures are taken. It doesn't matter for the fan. Most household models are equipped with asynchronous motors. In production, the number of phases is increased to three.

Finding a motor for a fan

One YouTube video suggested using a 3 volt DC motor from a hardware store. Tops a USB cord, works by rotating the laser disc blade. Useful invention? If you're tired of the extra port, this will help you survive the heat. It’s easier to take a processor cooler and power it from the system unit. The yellow wire goes to 12 volts (red to 5). The black pair is earth. You can assemble it from an old computer. Citizens of the Russian Federation are simply too lazy to invent, so we throw interesting equipment into a landfill.

Asynchronous fan motors operate without a starting capacitor... The peculiarity of fan motors is that they come directly with a winding. A couple of tips to help you get an engine:

Make a fan impeller

The question of what to make a fan from has not been resolved; the authors kept silent about the impeller. First things first, the refrigerator! The compressor is blown by an impeller. When you get the motor out, remove it. It will come in handy. Regarding washing machine, launch the drum onto an aircraft propeller. Plastic tank It's good to make a body. Heat the bend areas with a hair dryer.

Inspect the blender and equip it with an unnecessary laser disk shaped like an impeller. You can make a fan yourself using available materials. Not required high power, there is no point in trying too hard to hone in on the details. We believe that readers know how to make a fan with their own hands.

Eternal CPU cooler fan

We decided to please our readers by telling you how to make a fan. This is not the first review, I had to dig around to find something worthwhile. The idea of ​​​​creating an eternal fan that spins forever looks great. User mail.ru posted a design that looks attractive. Let's take a closer look, while thinking about how to make a fan that runs forever.

You know, of course, system units work quietly ( modern models). The slightest noise means: the cooler's axis is out of whack, or it's time to lubricate the old fan. They work for hours, the days turn into weeks, system unit will last for years. It became possible thanks to well-thought-out technology. Think about it, noise depends on the magnitude of the friction force. Mechanical energy becomes thermal and acoustic due to the presence of roughness. CPU coolers They rotate easily, just need to blow.

The author of the video - we apologize for the lack of a name, we justify: the video is in English - suggests assembling an eternal fan from an accessory. The fitting accuracy of the parts is high, the blade rotates easily. Costs are reduced to a minimum. The author of the video posted by the deirones channel noted: the processor fan is powered by direct current. I climbed inside and found four coils, equally spaced around the circumference, with their axes directed towards the center of the device.

There are no commutators inside, which means a paradoxical fact: the field of the coils is constant.

If the induction motor of a typical fan is powered by 220 volts alternating voltage, which creates a rotating magnetic field, in our case the picture is constant. You could say: inside the rotor sets in motion a commutator that creates the desired distribution. This is not true, and is confirmed by the author’s further train of thought and the result of experience. Western innovator decides to replace the coil permanent magnet. Indeed, there is no alternating field - why electric current?

The author demonstratively cuts off the power cord and places neodymium magnets ( hard drive) frame perimeter. Each is on the continuation of the coil axis. The work is completed, the blades begin to rotate vigorously. We believe that a principle is simply used that is hushed up in orthodox literature. Trade secret of the patent holder.

The initial movement of the blade is obtained by random air fluctuations. Reminiscent of a magnetron, the oscillations are caused by natural chaotic movement elementary particles. The question arose as to what determines the direction of rotation. The design is absolutely symmetrical. We decided to look into it and express our observations:

Agree, it’s more convenient than messing up USB ports and constantly wasting batteries. The eternal fan operates from an arbitrary position and is devoid of wires. We believe that the strength of the magnets plays a decisive role. The simple rule no longer works: more is better. A golden mean is emerging. When the blades spin from a random air flow, overcoming a field of neodymium pieces. Weak magnets are probably powerless to maintain stable rotation. The field strength must be exactly that created by the coils under the influence of +5 or +12 volts.

Correctly create an eternal fan

We discussed how to make a fan, measure the direction, force magnetic field coils They use special devices. A magnetometer, Teslameter, is formed by a magnetic induction converter, a measuring module. When fields interact, the resulting pattern is called coupling. The converter generates EMF. The size is determined by the measured strength of the magnetic field. Like two fingers! Costs 10,000 rubles.

The magnets will be located at a considerable distance from the axis. The coils are much closer. You need to know how the picture changes with distance. According to Coulomb's law, the force decreases in inverse proportion to the square of the distance, which is true for single charges of arbitrary sign. Magnetic poles individual ones have not yet been found in nature (it is not possible to create them), the cube of distance is included in the law. Let's say the distance to the coil from the axis is 1 cm, the diagonal perimeter is 10. This means that neodymium should be 10 x 10 x 10 = 1000 times stronger than a small coil.

Nobody obliges to place neodymium magnets around the fan perimeter on diagonals. The poles lie crosswise. Adjust the force of influence over a wide range. By placing neodymium magnets in the center of the sides of the fan frame, we significantly increase the field strength. Let's do the calculation. Let's say the hypotenuse of a triangle with a side of 10 cm is a diagonal. The distance to the center of the square will be equal to 10 / √2 = 7 cm. You see, the ratio drops from 1000, reaching 7 x 7 x 7 = 343. We are desperate to find strong neodymium magnets to create an eternal fan.

Let's measure the strength! A compass is suitable (there are custom designs that you can assemble yourself, for example, http://polyus.clan.su/index/indikatory_magnitnogo_polja_svoimi_rukami/0-52). One coil should be connected to the power supply. Then find the position, the arrow brought up will deviate by about 45 degrees (if you don’t like it, take any other azimuth). Then start experimenting with neodymium. Place the piece at different distances, ensuring that the arrow deflection coincides with that obtained when using the processor fan coil. Surely the distance is not equal to the diagonal, half the side, the neodymium will have to be broken and cut.

By sawing one edge along the length, we carefully break the parts on a nail, obtaining the required field strength to create an eternal fan. We assume that the induction is distributed proportionally to the volume. Today we explained clearly how to make a fan with your own hands!

Power supply

Anyone who wants to make a fan with their own hands sees 3 problems: getting a motor, power supply, and making a propeller. The parts must fit together. Three problems solved, you can start making a fan with your own hands. Today there are an abundance of switching power supplies at home. Think about it, it started in the 90s. Game consoles, mobile phones, other equipment. Equipment breaks down, switching power supplies remain. The voltage is sometimes non-standard; most motors operate on any voltage. The revolutions will simply change according to the voltage. There's a broken one lying around at home household appliances– Make a fan yourself immediately.

Homemade fan power supplies

People are constantly trying to make a special fan with their own hands. One issue is often beyond the scope of discussion: the power source. The design of the fan itself is so obvious that there is no point in going into more detail. So, it’s clear that there are an unimaginable number of batteries today. Will they be able to work for a long time? The answer is no. As a last resort, take the “crown”; in Soviet times it was considered a reliable source of energy. The power supply is bad, the power will gradually drop, the speed will decrease, and it will irritate people. Stability without additional effort is important. There is no small 12 volt battery - get ready: let's start looking for how to make a power source for a homemade fan.

The first thing that comes to mind is to screw up the computer. It is known that miniature devices are powered by a USB port. Gadgets are recharging. The USB port is a source of inexhaustible energy. The voltage is low, you will need a low voltage DC motor. We believe you can find it at home or buy it at a hardware store. How much port power will be: according to old standards, 2–3 W. Another thing is to find a host device with an updated version of the interface (2014 was considered a rarity). The developers promised to deliver 50 W (it’s hard to believe even more). True, there will be more wires, the rated voltages will increase. We remind you that according to tradition, power is supplied to the red (+), black (-) wires. White, green - signal.

It’s clear that it’s difficult to expect much power - even if the port supports it, the motor won’t pull it. It is recommended to look for a higher voltage. The motor must be supplied with higher voltage. For example, it is recommended to use a processor cooler. The supply voltage is less than the required 12 volts, the rotation speed will simply decrease. Beware of exceeding it - the motor may burn out.

We are looking for energy, the question is easier to solve than for 3 volts:

12 volt power supply for a homemade do-it-yourself fan

We suggest that you do not assemble a switching power supply, but make a regular one with your own hands. Let us remember that the former are distinguished by small-sized transformers. Therefore, the power supply will be relatively large in size. Will consist of the following parts:

• Step-down transformer. We will not name the number of turns in advance, the voltage is unknown, rectifying it with diodes, we get 12 volts. Of course, you can experiment, like the YouTube video about homemade radios Having captured the reader, we will look for a ready-made solution.
• The bridge is full-wave; by adding three to one diode, we increase the efficiency. Radio components are not very expensive.
• The backbone of the power supply is ready to homemade fan served for a long time, we will straighten the network ripple. After the bridge, we will turn on the low-pass filter and redraw the circuit from the Internet.

The output is a constant voltage with an amplitude of 12 volts. Be careful not to mix up the terminals. Where the “plus” comes out and where the “minus” comes out can be understood by studying the diagram. Below is a drawing of the bridge, look and read the explanations. In radio electronics, the direction of current is indicated opposite to the true one. Charges flow, according to popular belief, in the direction from plus to minus (towards electrons). Reading the diagram, you will see: the emitter of the diode, transistor, marked with an arrow, looks incorrectly. In the direction of movement of positive charges. Each one has marks and is indicated on the diagram by a huge triangle arrow. Consequently, we always find out “plus”, guided by the graphic symbols given in the drawing.

The figure shows: the plus will be on the right, transmitted according to the diode arrow to the lower output terminal. The minus will go up. With alternating voltage (roughly speaking), plus and minus will alternate from left to right, the name of the rectifier will become clear - full-wave. Works on the positive part of the voltage and the negative. Take power, low-frequency diodes. Solid size, power dissipation is relatively high. You can calculate using a simple formula taken from training course physics. We multiply the resistance of the open p-n junction (we leaf through the reference book) by the current consumed by the motor, taking the margin at least 2 times. The motor housing contains an inscription indicating the power, which can be divided by the voltage of 12 volts, simply multiplied by 2 - 3, and taken a diode with equivalent power dissipation (see reference book).

Now let's calculate the transformer... We went here http://radiolodka.ru/programmy/radiolyubitelskie/kalkulyatory-radiolyubitelya/, chose the Trans50 program, we will master it. Please note that there is software that allows you to calculate filter parameters. Do you regret that you decided to make a fan yourself? They offer to choose one of 5 windings. Steel is involved everywhere. You can make do, the losses will be great. The steel forms a magnetic circuit, the energy goes to the secondary winding. It's better to find an old rusty transformer. Times are bad; in the hungry 90s, landfills were littered with plates of scrapped windings. There were no problems with winding the transformers.

It's time to understand what voltage is required for the correct operation of the circuit. A term borrowed from electronics will help: effective voltage AC. The voltage across the active resistance creating a thermal effect is equal to constant voltage effective amplitude. To obtain the required voltage on the secondary winding, you need to divide 12 volts by 0.707 (one divided by the square root of 2). The authors received 17 volts. The engineering calculation has an error of 30%, let's take a small margin (part of the amplitude up to 1 volt will be lost on the diodes).

As for the secondary winding current (required for calculation), type something like “cooler power” into a search engine. Let's do it together with the readers. Smart articles write: the current consumption of the cooler is indicated on the case. Once you have the required parameter, we’ll plug it into the calculator. The author took the voltage of the secondary winding to be 19 volts. The voltage drop across the p-n junctions of powerful silicon diodes is 0.5 - 0.7 volts. Therefore, an appropriate reserve is needed. Smart heads searched and concluded that the processor cooler does not consume more than 5 W, therefore, the current is 5 divided by 12 = 0.417 A. We substitute the numbers into the downloaded calculator, and for the strip core we get the transformer design parameters:

1. The cross-section of the magnetic core for winding is 25 x 32 mm.
2. Window in the magnetic circuit 25 x 40 mm.
3. The magnetic core is finished with a frame for winding wire with a thickness of 1 mm and a cross-section of 27 x 34 mm.
4. The wire is wound along the larger side of the window, leaving a margin of 1 mm from the edges, for a total of 38 mm.

The primary winding is formed by 1032 turns with a diameter of 0.43 mm. The approximate length of the wire is 142 meters, the total resistance is 17.15 Ohms. The secondary winding consists of 105 turns of a copper core with varnish insulation with a diameter of 0.6 mm (length 16.5 meters, resistance 1 Ohm). Now readers understand: the question of what to make a fan from begins to be decided by the core...

How effective are the proposed technical solutions? Fans are known Ancient Egypt. Evidenced by Michael Jackson's video recommending “Remember the time.” The plot was hardly prepared without the consultation of archaeologists and historians. We would like to report that in Mexico, most ladies use fans. The Spaniards know how to deal with the heat; the country lies on the equator. Think about it...