Make an electronic device with your own hands.  Schemes for the home, do-it-yourself electronics for the house. Spot welding machine

Making electronic homemade products with your own hands gained popularity in the last century, when semiconductor devices appeared. With their help, it was quite easy to assemble devices needed for everyday life from old equipment. Today, repair and assembly of equipment for the home or cottage, for a car or garage can also be solved at home.

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Homemade devices for home and garden

Electrical homemade products for home and garden that use the power of electricity can be made by every electrician. Most devices are created using factory components and require only school knowledge of electricity.

Electric kebab maker

The electric kebab maker can be either horizontal or vertical. Stores usually sell vertical ones, and they do their job well after some modification.

To create a horizontal barbecue grill you will need a heating element and a frame resembling a barbecue. The heating element can be made from a ceramic tube and a nichrome spiral wound around it. The tube is secured through an insulating material in a metal casing. Drawings will be required to assemble the case.

Barbecue grill

An equally interesting idea is a kebab grill with an electric drive for rotating skewers. By adding an electric motor to a regular barbecue, you can get an excellent device that will cook barbecue in autonomous mode. To organize the skewer drive, you can use a motor from windshield wipers, from a washing machine, or any other 12-volt motor. Using a system of pulleys and a belt or gear drive, the rotation of the shaft is transmitted to the skewers, and the meat is slowly turned over the coals.

Homemade WI-FI antenna

This antenna will improve the reception quality and Wi-Fi speed in your home. According to reviews, after connecting it, the signal level rises from 5 to 27 Mbit.

For production you need:

• a small metal sieve or colander;
• Wi-Fi adapter (USB);
• USB cable;
• drill;
• epoxy resin;
• camera tripod;
• plastic clamps.

Manufacturing process:

1. We drill a small hole (14 mm) in the center of the sieve and insert a metal pin into it to secure the adapter.
2. We insert the connector from the USB cable into the prepared hole and secure it with epoxy resin. The USB connector after gluing must be strictly perpendicular to the plane of the sieve, then the device will work more efficiently.
3. Then, using two zip ties, “ears” are made through which the cable is attached.
4. We fix the product on a camera tripod. We drill a hole with a diameter of 12 mm in the antenna and tighten it with a nut.

Necessary materials Insert the pin into the drilled hole Glue the USB cable Securing the cable Tripod Installing the antenna using a tripod

Electrical homemade products for the garage

Let's look at a few projects useful homemade products for the garage.

Homemade chandelier

If in your garage low lighting, then an improvised chandelier will be very useful. To make a bifurcating chuck, you will need a pair of angular chucks, which are sold at a regular hardware store.

Sequencing:

1. We remove the wires from the sockets and fasten them with a plastic tie. We get a socket for two lamps. All that remains is to connect them to the electrical network.
2. To do this, we use the base of a fluorescent lamp. Carefully break out the lamp, then solder the wires from our design to the contacts of the base.
3. We insulate them well and attach the base on top of the cartridges.

The use of ordinary light bulbs in this design is undesirable - the sockets may melt from heating.

LED device

Another lighting option could be a homemade LED lighting device.

To make it you will need:

• old fluorescent lamp;
• LED Strip Light;
• connecting wires.

The manufacturing sequence is as follows:

1. An LED strip is glued to the lamp body in one or several rows.
2. The connecting wires are connected and brought to the lamp switch.
3. The assembled device is tested.

Spot welding machine

A necessary device in the garage will be a homemade spot welding machine, the basis of which is a transformer from an old microwave oven. A necessary condition is that the transformer must be working in order not to rewind all the windings.

The process of assembling the welder is quite simple:

1. The transformer is dismantled.
2. Carefully remove the secondary winding.
3. Two shunts are removed.
4. A secondary winding of two or three turns is made of thick wire (with a diameter of at least 10 mm).
5. Electrodes for resistance welding are made from a copper rod with a diameter larger than the wires.

Homemade spot welding tool

Useful DIY items for fishing

Among the homemade products you can find many interesting ideas for use in camping conditions, as well as hunting and fishing.

Electronic alarm

An example would be an electronic signaling device for fishing with a regular fishing rod or other equipment. A simple biting device can be assembled in just half an hour. For it you will need an old beeper keychain and a strip of plastic 1-2 mm thick.

Alarm assembly:

1. The keychain is attached to the rod.
2. A strip of plastic is glued to the fishing line and inserted between the contacts of the key fob.

Now when the fish bites, the fish will pull the line, the plastic will fly out, the contacts will close and the key fob will work.

Underwater camera for ice fishing

Using a homemade underwater camera for winter fishing, you can see if there is fish under the hole. And this simplifies the fishing process.

To make it you will need:

• small camera;
• sealed camera box;
• small TV;
• car battery to power the camera;
• extension;
• inverter;
• lead for cargo;
• ultraviolet diodes for illumination during underwater shooting;
• superglue, electrical tape, sealant.

Build process:

1. Two holes are made in the upper part of the box. An extension cable is inserted through one. Through the second is the wire that connects the camera to the TV.
2. Several more holes are made in the box into which light bulbs are inserted for illumination. The wires from the light bulbs are soldered into one circuit (for example, with a parallel arrangement), which is connected to a cable that provides power.
3. The holes are sealed with glue and tape for a tight seal.
4. Lead is melted and small elongated bars are poured out of it. They are placed at the bottom of the box.
5. Set up the camera and connect it to the cable. After which it is carefully placed in the box so that it has a clear forward and horizontal direction and transmits a high-quality image. For stability, the chamber is surrounded by soft material.
6. A torso (rope, belt) is attached to the box, which will be used to lower the camera to depth. For convenience, you can combine it, the power cable and the communication wire between the video camera and the TV into one core, secured with electrical tape.
7. Connect the power cable of the video camera to the battery and test the device.

Homemade fish bait

You can make a good bait for fishing yourself. This will be a device assembled based on a simple multivibrator.

You will need:

• sound emitter, for example, from a children's toy;
• wires;
• a small plastic jar, for example, for medicinal tablets;
• electronic board;
• regulator with plastic rod;
• a piece of foam;
• batteries;
• weights for the float;
• volume control.

The bait is assembled as follows:

1. You need to solder the circuit and check it.
2. Two wires are soldered to the sound emitter. Then they are carried inside the case and connected to the board.
3. A regulator with a plastic rod is placed in the lid of the jar.
4. A dense circle cut out of foam plastic is installed on top of the board, which separates the board from the battery.
5. Weights are attached to the bottom of the jar so that the container floats on the water like a float.
6. The regulator sets the frequency and changes the sound.

Bait scheme - 1 Bait scheme - 2

Electronic homemade products for cars

Car enthusiasts create homemade products with their own hands to improve appearance and ease of use of the car.

Electrical auto tester

A simple homemade electrical probe is perfect for a car. It can show the presence of a voltage of 12 volts in an electrical circuit. It is used to check the serviceability of relays, as well as light bulbs and other equipment. You can make such a device from a syringe and LEDs.

Assembly diagram:

1. Two LEDs are soldered with opposite terminals (plus one to the minus of the other and vice versa).
2. A steel probe is connected to one of the solders through a resistance of 300 Ohms. To the other solder there is a contact for batteries.
3. The design is inserted into the syringe so that the probe comes out of the hole for the needles. Most of the probe is insulated with a PVC pipe.
4. 4 LR44 batteries are inserted into the syringe so that one of the poles is connected to the LED contact.
5. The other pole of the batteries is connected to a flexible wire with an alligator clip.

The video explains how to make a syringe tester. Filmed by ILYANOV channel.

Light switch

The scheme for smoothly turning off the lights in the car interior is quite simple to make. Such electronics are suitable for any car. A small board consisting of a capacitor and diodes is soldered parallel to the interior lamp terminals. The drop in electricity voltage will occur gradually and create the effect of a gradually fading light.

Car subwoofer

To make a car subwoofer with your own hands, you must first purchase a speaker. You need to start from its dimensions when calculating the size of the case.

The simplest and most suitable form of a subwoofer for the trunk is a truncated pyramid with a slope similar to that of the rear seats.

LED fog lights

You can make LED car fog lights with your own hands.

For creativity you will need:

• two ten-watt LEDs;
• 2 lenses from an old projector;
• gaskets from plastic pipes;
• LM317T microcircuits;
• resistors.

Instructions for assembling the craft:

1. LEDs are installed on pre-prepared aluminum radiators.
2. The structure is assembled from headlight housings, lenses from projectors, gaskets and diodes on radiators.
3. The fog lights are powered through current stabilizers on LM317T microcircuits and resistors.

Car carrying

A very convenient car carrier is made from a computer USB lamp. It is compact and you can connect the device to any place in the car wiring.

Manufacturing scheme:

1. Remove the contacts from the USB plug.
2. In the plug body we connect the wires of the lamp and the car alligator clips.
3. To mount it in the right place (even horizontally), a magnet is placed on the plug.

For those just starting to take their first steps into electronics, it is important to start somewhere. Well, we invite you to familiarize yourself with ideas that may come in handy in the future and at the same time give you an idea of ​​how something should be done. What to choose if you want to make simple ones with your own hands? Here are options that can be used in everyday life.

Simple power regulator for smooth switching of lamps

This type of device has found wide application. The simplest is a regular diode, which is connected in series with the load. Such regulation can be used to extend the life of an incandescent lamp, as well as to prevent overheating of the soldering iron. They can also be used to change power over a wide range of values. First, there will be the simplest DIY electronic crafts. You can see the diagrams here.

How to protect yourself from mains voltage fluctuations

This device turns off the load if the mains voltage is outside the permissible limits. As a rule, a deviation of up to 10% from the norm is considered normal. But due to the peculiarities of the energy supply system in our country, such limits are not always observed. So, the voltage can be 1.5 times higher, or much lower than necessary. The result is often unpleasant - the equipment fails. Therefore, there is a need for a device that will turn off the load before something has time to burn out. But when creating such a homemade product, you need to be careful, since the work will be carried out with considerable stress.

How to make a safety transformer

Transformerless power supplies are often used in various electronic designs. Typically, such devices have low power, and to avoid electrical injury, they are placed in an insulating plastic case. But sometimes they need to be configured, and then the security is broken. To avoid possible injury, use an isolating safety transformer. It will also be useful when repairing such devices. Structurally, they consist of two identical windings, each of which is designed for the network. As a rule, the power of transformers of this type ranges from 60-100 W, these are the optimal parameters for setting up various electronics.

Simple emergency lighting source

What should you do if you need to ensure that some area remains illuminated in the event of a power outage? The answer to such calls can be an emergency lamp made on the basis of a standard energy-saving lamp, the power of which does not exceed 11 Watts. So if you need light somewhere in the corridor, utility room or workplace, this homemade product will come in handy. Usually, if there is voltage, they operate directly from the mains. When it disappears, the lamp begins to function on battery power. When the mains voltage is restored, the lamp will work and the battery will automatically charge. The best electronic DIY projects have been left for the end of the article.

Boost power regulator for soldering iron

In cases where it is necessary to solder massive parts or the mains voltage often drops, using a soldering iron becomes problematic. And a step-up power regulator can help out of this situation. In these cases, the load (i.e., the soldering iron) is powered using rectified mains voltage. The change is carried out using an electrolytic capacitor, the capacitance of which allows you to obtain a voltage greater than 1.41 network voltage. So, with a standard voltage value of 220 V, it will give 310 V. And if there is a drop, say, to 160 V, then it will turn out that 160 * 1.41 = 225.6 V, which will allow for optimal operation. But this is just an example. You have the opportunity to make a scheme that is suitable specifically for your conditions.

The simplest twilight switch (photo relay)

As new parts are created, fewer components are now needed to make a device. So, for a regular twilight switch, only 3 of them are needed. Moreover, thanks to the versatility of the design, multi-purpose use is possible: in an apartment building; for lighting the porch or courtyard of a private home, or even a separate room. Pointing out the features of such a design as a twilight switch, it is also called a “photo relay”. You can find many implementation schemes that were made either by amateurs or industrialists. They have their own set of positive and negative properties. Negative properties are usually either the need for a constant voltage source or the complexity of the circuit itself. Also, when buying cheap and simple parts or entire sets, people often complain that they simply burn. The functionality of the scheme is based on three components:

1. Photocell. It is usually understood as photoresistors, phototransistors and photodiodes.
2. Comparator.
3. Triac or relay.

When there is daylight, the resistance of the photocell is low and does not exceed the response threshold. But as soon as it gets dark, the structure will be turned on at that very moment.

Conclusion

Here are some interesting electronic crafts you can make with your own hands. The main thing in cases where something doesn’t work out is to keep trying, and then everything will work out. And once you gain experience, you can move on to more complex schemes.

Many people consider themselves far from physics. But even with minimal knowledge (even what you got at school is enough) you can do something interesting and, most importantly, special. We are talking about electronic homemade products with your own hands. Their assembly schemes are usually not complicated. We will consider several simple options for beginning electronics engineers in this article.

Cat's house

Electronic homemade products are a flight of fancy combined with knowledge of electronics. So, for example, you can make an excellent house for a cat from an old computer monitor. To do this you just need to disassemble it. When the bottom and walls of the monitor are separated from the circuit boards, kinescope and all other parts, you just need to twist them back. To make the animal more comfortable, you need to make bedding inside.

Music Box

Electronic homemade items very often serve as objects that bring joy to their owners. A striking example of this is music Box. Moreover, it does not just play music. It completely preserves space for storing small items.

To work you will need:

• the box itself;
• music module with transistor;
• speaker (suitable for a phone or player);
• switch (can be from a wall telephone);
• compartment for AAA batteries (for example, from children's toys or a flashlight).

The first step is to solder the 8050 transistor to the music module (the circuit is shown in the figure above). Next, conductors are soldered to connect the power supply and speaker. It is important to maintain correct polarity when applying power. The speaker and board are attached using glue. The resulting design should fit into the lid of the box.

After this, the switch is installed. A loop is made from the lace and placed over the stem. It is necessary for management. The second end of the lace is glued to the inside of the box. Its length is selected in such a way that the music module is triggered exactly at the moment the lid is fully opened.

The electronic module is hidden with a cut out piece of cardboard or fabric.

Electronic fishing rod

Electronic homemade circuits offer fishermen to make an electronic fishing rod. It runs on a AA battery. It can be thrown to a depth of up to 5 meters. In this case, the operating time is up to 12 hours.

Electronic homemade products of this kind work on a multivibrator circuit. A piece of board 2x6 cm is enough, on which all the elements of the circuit will be attached. The relay is selected with a resistance of up to 2.4 ohms.

Homemade tattoo machine

Electronic homemade circuits in this case provide for the presence of an electric motor with a power of 12-18 W. As a rule, all such motors have a gear on the shaft. It is necessary to glue a medium-sized button with 4 holes to it (they must remain free).

Next, choose a suitable handle. It will be the body of the entire product and guide the needle. A mechanical pencil works well. To connect it to the motor, a bracket is made in the shape of the letter “G”. It can be made from the handle of a spoon (fork).

A needle is cut from a guitar string. Its length should be slightly longer than the pencil tube. It should be from the center of the motor to the tip of the tube. The needle must be boiled for 10 minutes.

We connect the handle and bracket using electrical tape. The long side of the staple runs along the handle. Fold the staple flush with the top end of the pencil. There shouldn't be any swaying. A motor with a button is attached to the smaller side of the bracket. We pass the handle through the pencil to the motor and insert it into the hole of the button. At the last stage, homemade electronic homemade products are connected to a power source.

Stationary lamp

For illuminating the workspace at the table, homemade electronic devices offer many options. One of them involves the use of a fluorescent lamp and a metal profile, which is used to fasten plasterboard sheets.

The profile has the shape of the letter “P” in cross-section. Thanks to this, it will serve not only as a holder, but also to direct (reflect) light from top to bottom.

The profile must be bent. To do this, two sides are cut. After bending, the edges are connected with self-tapping screws to add rigidity. The lamp has a switch. We make a hole in the profile for it. Next, the lamp is attached to the base. Its rectangular version will help increase the strength of the profile. To attach it to the table, screw a metal corner to one edge of the profile.

We do it for our loved ones

When you love, you always want to please your “other half.” And this desire intensifies on the eve of Valentine's Day. Electronic homemade products will help solve the problem of finding a gift. You can prepare a wonderful and amazing gift with your own hands. For example, an LED valentine.

It is assembled from ready-made elements included in a special set. It can be ordered in the online store. The set includes the following parts: transistors (3 pcs.), resistors (6 pcs.), LEDs (18 pcs.), electrolytic capacitor (3 pcs.), printed circuit board.

Assembling the product is easy. To do this, you only need a soldering iron with low power, which is also used to assemble other electronic homemade products with your own hands. Assembly diagrams are included in the kit. They are guided during work. In this case, several points must be observed:

• When installing capacitors, it is necessary to take into account the polarity of the electrodes. The required electrode is marked on the body of the part.

• When installed, resistors must correspond to the specified ratings. They are marked on the body with a color code.

• Next, LEDs are installed.

• For mounting transistors there is a key in the form of a form on the case.

When working, it is important to solder parts quickly, avoiding overheating. The board will be powered by a 3 V battery. There are two wires from the board to the battery compartment, which, by the way, fits from any electronic toy. The battery compartment is attached to the bottom of the back of the board using glue. This will allow the board to be installed in a vertical position.

DIY motion sensor connection diagram

It happens that you need to install lighting in your dacha or in your home. will be triggered by movement or a person or someone else.

A motion sensor, which I ordered from Aliexpress, works well with this function. The link to which will be below. By connecting light through a motion sensor, when a person passes through his field of vision, the light turns on and stays on for 1 minute. and turns off again.

In this article I’ll tell you how to connect such a sensor if it doesn’t have 3 contacts, but 4 like this one.

DIY power supply from an energy-saving light bulb

When to get 12 Volts for LED strip, or for some other purpose, there is an option to make such a power supply with your own hands.

DIY fan speed controller

This regulator allows for smooth adjustment variable resistor fan speed.

The circuit of the floor fan speed controller turned out to be the simplest. To fit into the case from the old charger Nokia phone. The terminals from a regular electrical outlet also fit in there.

The installation is quite tight, but this was due to the size of the case..

DIY plant lighting

DIY plant lighting

There may be a problem with lack of lighting plants, flowers or seedlings, and there is a need for artificial light for them, and this is the kind of light we can provide on LEDs with your own hands.

DIY brightness control

DIY brightness control

It all started after I installed halogen lamps for lighting at home. When turned on, they often burned out. Sometimes even 1 light bulb a day. Therefore, I decided to make a smooth switching on of the lighting based on a brightness control with my own hands, and I am attaching a diagram of the brightness control.

DIY refrigerator thermostat

DIY refrigerator thermostat

It all started when I returned from work and opened the refrigerator to find it warm. Turning the thermostat control did not help - the cold did not appear. So I decided not to buy new block, which is also rare, and make an electronic thermostat yourself on the ATtiny85. The difference with the original thermostat is that the temperature sensor is on the shelf and not hidden in the wall. In addition, 2 LEDs appeared - they signal that the unit is turned on or the temperature is above the upper threshold.

DIY soil moisture sensor

DIY soil moisture sensor

This device can be used for automatic watering in greenhouses, flower greenhouses, flower beds and indoor plants. Below is a diagram on which you can make a simple sensor (detector) of soil moisture (or dryness) with your own hands. When the soil dries out, voltage is applied with a current of up to 90 mA, which is quite enough, turn on the relay.

It is also suitable for automatically turning on drip irrigation to avoid excess moisture.

Fluorescent lamp power supply circuit

Power supply circuit for a fluorescent lamp.

Often when energy-saving lamps fail, it is the power supply circuit that burns out, and not the lamp itself. As is known, LDS with burnt filaments, it is necessary to supply the network with rectified current using a starterless starting device. In this case, the filaments of the lamp are bridged by a jumper and a high voltage is applied to it to turn on the lamp. There is an instantaneous cold ignition of the lamp, with a sharp increase in voltage across it, upon start-up without preheating the electrodes. In this article we will look at starting an LDS lamp with your own hands.

USB keyboard for tablet

USB keyboard for tablet

Somehow, suddenly, I took something and decided to buy a new keyboard for my PC. The desire for novelty cannot be overcome. Changed the background color from white to black, and the letter color from red-black to white. A week later, the desire for novelty naturally disappeared like water into sand (an old friend is better than two new ones) and the new thing was sent to the closet for storage - until better times. And now they came for her, she didn’t even imagine that it would happen so quickly. And therefore the name would be even better suited not which is, but how to connect usb keyboard to the tablet.

DIY clock with IN-14 lamps

DIY clock with IN-14 lamps

I have long wanted to post an article on making DIY watches with IN-14 lamps, or as they say, a watch in the steam punk style.

I will try to present only the most important things step by step and focusing on key points. The clock indication is clearly visible both day and night, and they themselves look very nice, especially in a good wooden case. Anyway, let's get started.

Those who do radio electronics at home are usually very inquisitive. Amateur radio circuits and homemade products will help you find a new direction in your creativity. Perhaps someone will find an original solution to this or that problem. Some homemade products use ready-made devices, connecting them in different ways. For others, you need to completely create the circuit yourself and make the necessary adjustments.

One of the simplest homemade products. More suitable for those who are just starting to craft. If you have an old but working cell phone with a button to turn on the player, you can use it, for example, to make a doorbell for your room. The advantages of such a call:

First you need to make sure that the selected phone is capable of producing a sufficiently loud melody, after which it must be completely disassembled. Basically, the parts are secured with screws or staples, which are carefully folded back. When disassembling, you will need to remember what goes with what, so that later you can put everything back together.

The player's power button is unsoldered on the board, and two short wires are soldered in its place. These wires are then glued to the board so the solder doesn't come off. The phone is going. All that remains is to connect the phone to the call button via a two-wire wire.

Homemade products for cars

Modern cars are equipped with everything you need. However, there are times when homemade devices are simply necessary. For example, something broke, they gave it to a friend, and the like. That’s when the ability to create electronics with your own hands at home will be very useful.

The first thing you can tamper with without fear of damaging your car is the battery. If you don’t have a battery charger at hand at the right time, you can quickly assemble it yourself. To do this you will need:

A transformer from a tube TV is ideal. Therefore, those who are interested in homemade electronics never throw away electrical appliances in the hope that they will be needed someday. Unfortunately, two types of transformers were used: with one and with two coils. To charge a battery at 6 volts, any will do, but for 12 volts only two.

The wrapping paper of such a transformer shows the winding terminals, the voltage for each winding and the operating current. To power the filaments of electronic lamps, a voltage of 6.3 V with a high current is used. The transformer can be remade by removing the extra secondary windings, or you can leave everything as is. In this case, the primary and secondary windings are connected in series. Each primary is rated at 127 V, so combining them produces 220 V. The secondary are connected in series to produce an output of 12.6 V.

Diodes must withstand a current of at least 10 A. Each diode requires a radiator with an area of ​​at least 25 square centimeters. They are connected into a diode bridge. Any electrical insulating plate is suitable for fastening. A 0.5 A fuse is included in the primary circuit, and a 10 A fuse in the secondary circuit. The device does not tolerate short circuits, so the polarity should not be confused when connecting the battery.

Simple heaters

During the cold season, it may be necessary to warm up the engine. If the car is parked where there is electrical current, this problem can be solved using a heat gun. To make it you will need:

• asbestos pipe;
• nichrome wire;
• fan;
• switch.

The diameter of the asbestos pipe is selected according to the size of the fan that will be used. The performance of the heater will depend on its power. The length of the pipe is everyone's preference. You can assemble a heating element and a fan in it, or just a heater. When choosing the latter option, you will have to think about how to allow air flow to the heating element. This can be done, for example, by placing all components in a sealed housing.

Nichrome wire is also selected according to the fan. The more powerful the latter, the larger diameter nichrome can be used. The wire is twisted into a spiral and placed inside the pipe. For fastening, bolts are used that are inserted into pre-drilled holes in the pipe. The length of the spiral and their number are selected experimentally. It is advisable that the coil does not become red hot when the fan is running.

The choice of fan will determine what voltage needs to be supplied to the heater. When using a 220 V electric fan, you will not need to use an additional power source.

The entire heater is connected to the network via a cord with a plug, but it itself must have its own switch. It can be either just a toggle switch or an automatic machine. The second option is more preferable; it allows you to protect the general network. To do this, the operation current of the machine must be less than the operation current of the room machine. A switch is also needed to quickly turn off the heater in case of problems, for example, if the fan does not work. This heater has its disadvantages:

• harmful to the body from asbestos pipes;
• noise from a running fan;
• smell from dust falling on the heated coil;
• fire hazard.

Some problems can be solved by using another homemade product. Instead of an asbestos pipe, you can use a coffee can. To prevent the spiral from closing on the jar, it is attached to a textolite frame, which is fixed with glue. A cooler is used as a fan. To power it, you will need to assemble another electronic device - a small rectifier.

Homemade products bring those who do them not only satisfaction, but also benefits. With their help, you can save energy, for example, by turning off electrical appliances that you forgot to turn off. A time relay can be used for this purpose.

The simplest way to create a time-setting element is to use the charging or discharging time of a capacitor through a resistor. Such a chain is included in the base of the transistor. The circuit will require the following parts:

• high-capacity electrolytic capacitor;
• transistor p-n-p type;
• electromagnetic relay;
• diode;
• variable resistor;
• fixed resistors;
• DC source.

First you need to determine what current will be switched through the relay. If the load is very powerful, you will need a magnetic starter to connect it. The starter coil can be connected via a relay. It is important that the relay contacts can operate freely without sticking. Based on the selected relay, a transistor is selected and it is determined what current and voltage it can operate with. You can focus on KT973A.

The base of the transistor is connected through a limiting resistor to a capacitor, which, in turn, is connected through a bipolar switch. The free contact of the switch is connected through a resistor to the power supply negative. This is necessary to discharge the capacitor. The resistor acts as a current limiter.

The capacitor itself is connected to the positive bus of the power source through a variable resistor with high resistance. By selecting the capacitance of the capacitor and the resistance of the resistor, you can change the delay time interval. The relay coil is shunted by a diode, which turns on in the opposite direction. This circuit uses KD 105 B. It closes the circuit when the relay is de-energized, protecting the transistor from breakdown.

The scheme works as follows. IN original condition The base of the transistor is disconnected from the capacitor and the transistor is turned off. When the switch is turned on, the base is connected to the discharged capacitor, the transistor opens and supplies voltage to the relay. The relay operates, closes its contacts and supplies voltage to the load.

The capacitor begins to charge through a resistor connected to the positive terminal of the power source. As the capacitor charges, the base voltage begins to rise. At a certain voltage value, the transistor closes, de-energizing the relay. The relay switches off the load. In order for the circuit to work again, you need to discharge the capacitor; to do this, switch the switch.