Soldering iron made from a 12 volt resistor. Homemade miniature low-voltage soldering iron. Soldering iron assembly steps

Many people use homemade soldering irons. There are quite a lot of implementation options, since these tools are sculpted from what is at hand or can be easily found. The most labor-intensive process is to make a soldering iron, similar to a factory one, but of low power. Here is an example of what and how to make a miniature one at home. It is assumed that the soldering iron will receive power not directly from the network, but through a 220/12 V transformer.

You will need the following materials:

• copper wire with a diameter of 1.5 mm - about 40 mm long
• copper foil - a small rectangle 30x10 mm or a little larger
• nichrome wire 0.2 mm – 350 mm
• a tin tube or piece of tin to make a casing for the heating element
• silicate glue (liquid glass)
• talc for the production of an insulating layer with the addition of silicate glue
• handle made of heat-resistant plastic
• electrical cord with plug

Some auxiliary things will also be required:

• heat source (electric or gas oven)
• standard tools (nippers, tweezers, pliers, file)
• non-standard devices (something in the form of a narrow small spatula - wooden or plastic)
• a lot of rags (remove very sticky insulating mixture from hands and tools)

Sequence of actions for assembling the tool

The description of the process is given schematically, since implementation usually does not cause difficulties.

Important! The finished soldering iron can be connected, as already mentioned, to the network via a transformer or to a 12-volt power supply rated for a current of 1 A.

This soldering iron can work with microcircuits, but care should be taken to protect against static electricity.

An alternative option to such a soldering iron is of interest to those who are unpretentious appearance device that will have to work. The trick of this solution is that a PEV-10 or PEV-7.5 resistor is used as a heating element. All that remains is to insert the tip, which is fixed in copper tube, tightly seated inside the resistor, and take care of good fixation of the resistor contacts, which cannot withstand certain mechanical loads.

Video on how to make a mini soldering iron with your own hands

The following video will help you figure out how to make a homemade mini soldering iron:

For soldering electronic circuits, it is often necessary to observe special caution when heating the terminals of semiconductor elements. They can be very picky about temperature.

In addition, sometimes when debugging a circuit you have to solder with the power connected. In this case, using a regular soldering iron powered by a 220 Volt network is dangerous. For such cases, it is better to use an electric soldering iron that operates on a voltage of 12 volts.

A soldering iron designed for 12 Volts can operate on both AC and DC power.

A soldering iron operating on direct current can even be connected to the vehicle’s on-board network, provided that its power does not exceed the rated power of the vehicle’s electrical wiring.

There are many designs of soldering irons on sale that use low voltage. They can be distinguished by the obligatory inscription on the body and packaging.

This voltage must also be indicated in technical specifications tool. If you have an unnecessary 220-volt soldering iron, you can make a 12-volt one yourself.

Remaking an old soldering iron

In order to remake a standard soldering iron, you need to disassemble it and remove the heating element. Instead, you need to wind a nichrome thread with a thickness of 0.02-0.20 mm on a mica substrate. The thread can be removed from any used electrical appliance, for example, a hair dryer.

The length of the filament is selected experimentally depending on the thickness and the required degree of heating of the soldering iron. When winding the thread, you must ensure that the turns do not touch each other.

The sequence of work is as follows:

• after selecting the length of the wire, the turns are fixed using some heat-resistant glue;
• The thread is connected at both ends by wires to the power source. It could be a 12-volt converter, a power tool battery, or a car battery;
• The body of a new 12-volt soldering iron must be assembled and it will be no different from the previous one.

In order not to accidentally connect the tool to a 220 volt network, it is recommended to make a catchy, clearly visible inscription on the handle - “12v”.

From a resistor

You can make a miniature homemade soldering iron for 12 volts using permanent metal film resistors, for example, MLT-2 with a power of 2 W.

They work even with an overload of up to 6-10 times, so it is not difficult to achieve power output of up to 12-20 W from them. But a significant part of it will be wasted on heat exchange with air due to the relatively large surface area of ​​the resistor. For manufacturing you will need a resistor with a nominal value of 24-27 Ohms.

One of its fairly thick leads will serve as a soldering iron tip, the second – as a contact for the power wire.

The resistor body near the tip contact must be cleaned of paint and tightly wrapped with a second supply wire. The working circuit of the soldering iron is ready.

All that remains is to place it in a case that will be convenient to use. To do this, the resistor is wrapped in a heat-resistant heat-insulating material, for example, fiberglass, and placed in a plastic tube of a suitable diameter.

Car use

There are few components and parts left in modern cars that can be repaired independently, outside of a garage or workshop. Most likely, these could be damaged wire harnesses at the bends.

Such malfunctions are easy to fix on the road. It is enough to remove excess insulation and twist the wires, then protecting the twist with insulating tape.

But the car's wiring works in very difficult conditions. It is subject to vibrations, frequent changes in temperature and humidity, especially in winter.

Under such conditions, contact in the twist may be lost, and when using a conventional single-wire electrical diagram Loss of contact can have unpredictable effects on the vehicle's behavior.

To prevent this undesirable phenomenon, it is recommended to solder the twist. For this you will need a car soldering iron powered by a cigarette lighter.

Almost all car cigarette lighters are powered by a line of wires rated for a current of up to 15 A. This is quite enough to connect a soldering iron with a power of up to 100 Watts. And more is unlikely to be needed. The cigarette lighter itself is also converted into a socket. It turns out to be a miniature infrared hair dryer.

In older vehicles, soldering may be necessary to repair relay and fuse mounting blocks, or to solder terminals to wires that have been broken during use.

The operating voltage of soldering irons can have a different range of values ​​- from 220V and below. The trend towards stricter safety requirements has led to the fact that only powerful soldering irons use full household voltage for operation. It's not just a matter of safety. Malfunction of a high-voltage tool (insulation breakdown, short circuit) can damage radio equipment that is soldered using a soldering iron.

Soldering irons with voltages of 24, 36 and 42V are most widely used for repairing various devices. Such voltages are safe for both people and equipment.

Where is a low-voltage soldering iron needed?

To carry out repair work automotive devices Electric soldering irons are available with lower voltage - 12V. This is the voltage of the car's on-board network. If repairs are carried out far from a service station or garage, then only the car battery can serve as a voltage source. A breakdown of electrical equipment during a trip may result in a tow truck being called if it does not happen while additional equipment(radio, car refrigerator), but in the on-board network itself.

Power restrictions

The use of low-voltage soldering irons encounters a fundamental limitation on the permissible power of the tool, because, according to the elementary law of electrical engineering, with a decrease in voltage, more current is required for the same power. So, a soldering iron with a power of 40 W at a voltage of 36 V consumes a current of slightly more than 1A, and a 12-volt one will require more than 3 amperes. It requires large diameter supply wires, firstly, according to the permissible heating of the wires, and secondly, according to the voltage drop across them.

Connecting a 12V soldering iron

To connect third parties electrical devices In most cars there is only one option - through the cigarette lighter socket.

Before using it to connect a powerful soldering iron, you should study the electrical circuit of the car in terms of the purpose and power of the fuses. Many car models have electrical equipment in which other devices are included in the cigarette lighter power circuit. For example, on popular model VAZ-2109, the rear window heating is included in the cigarette lighter circuit, and exceeding the permissible current consumption can lead to blown fuses and inoperability of some of the vehicle’s electrical equipment.

Thus, a powerful electric soldering iron must be connected directly to the battery. This also achieves a reduction in the voltage drop on the switching elements and connecting wires.

Important! Using a powerful soldering iron for a long time can drain the battery to a critical level. It is necessary to remember this and prevent discharge.

Soldering iron selection

When purchasing a low-voltage soldering iron, you need to imagine the purposes for which it will be used. A tool with a power of up to 40 W can only be used for soldering electronic equipment and thin wires. The car's power wiring has a large cross-section of wires and is an effective heat sink. It is almost impossible to reliably solder such conductors with a low-power 12-volt soldering iron, especially in cold weather.

The temperature of the soldering iron tip should be at least 300-400°C. At a lower temperature, the solder will be difficult to melt. It would be good if the soldering iron is equipped with a power regulator, but such models are much more expensive.

All elements of the soldering iron should look strong and reliable. The tip and handle of the tool should sit tightly in place and not dangle. Connecting wires from a good and quality instrument They have a large thickness and at the same time good flexibility. It is inconvenient to use the tool when soldering miniature radio elements and putting effort into bending the power wires.

DIY soldering iron

If you want to do something with your own hands and have the ability to work with tools, you can make a 12-volt soldering iron yourself. It will look a little unpresentable, but the reliability is much higher than that of cheap Chinese instruments.

To make a homemade soldering iron you need:

• Powerful (at least 10W) ​​wirewound resistor with a resistance of 5-6 Ohms;
• Copper rod with a diameter corresponding to the diameter of the internal hole of the resistor;
• A thinner copper rod for the sting. You can grind a section of a thick rod, but then if the tip burns, you will have to change the entire element completely;
• Insulating material for the soldering iron handle (textolite, plywood);
• Connecting wires with a cross section of 1-1.5 mm2;
• Plug for cigarette lighter socket.

After assembling the heating element, the wires are soldered to it, and the handle is attached using a metal clamp through an asbestos gasket.

Video

A soldering iron designed for 12 Volts from your own autohorse can be made in an hour or two, which can be very useful for a home craftsman. The basis of the heating element will be... you won’t believe it - a resistor PEV-10 or PEV-7.5!
This design is just an example, and the flight of fancy of crazy hands is unlimited here. The main thing here is to have two copper rods of different diameters and the PEV resistor itself.

I found a description of such an original design on the Internet. Damn, live forever and learn! For how many years I have been interested in electronics and various crafts, but I have never heard of this and would not have thought about it myself.

In fact, if you are not in the garage, you will need to solder something into some device in your car, because you will not have 220 volts at hand. So such a homemade soldering iron, made with your own hands in an hour, can really help you out in such a situation. And if you have a powerful old transformer with a 12-volt output lying around, then this miracle soldering iron will also work at home!

PEV resistors

These resistors come in high power. I remember at the factory when I worked as a radio assembler, we had soldering irons at 36 volts and they were regulated in a primitive way: through the sequential connection of such huge resistors into their power circuit, similar to these, but only with cylindrical regulation. For this, resistors of the PPG-25G type were used. As the temperature decreased, part of the energy was dissipated on this resistor, and given that we had 40-watt soldering irons, these resistors got really hot.

What Russian ingenuity! In fact: resistors are made of ceramics, designed for enormous heating (I know, I’m telling you as a practitioner), they are made firmly, reliably - it can be used as a heating element of a soldering iron. The number in the name means the power of the resistor, if you haven’t guessed.

The design of a homemade soldering iron

Well, now all that remains is to fix the soldering iron tip inside the PEV-10 (PEV-7.5) resistor, and attach a handle to its terminals. And, as I mentioned, the conclusions, like everything else in these resistors, are made for centuries - you’ll tear them off!

This is roughly how a sting is made, together with a body that transmits heat, from two copper rods, inserted inside the resistor.

In the large rod, recesses are drilled on both sides: for the tip itself and for the mounting bolt. Then threads are cut into them. The thread is also cut on the tip of the future soldering iron.

On the large rod you need to make a groove for the locking steel ring, then put it on.

After which the structure of the tip and the heating element of the soldering iron are assembled together.

Hehe, cheap and cheerful! 🙂 Similar? Hände hoch!

I’ll add on my own that after assembly, the resistor can be wrapped with asbestos cord to reduce heat loss.

The author made the handle from two identical halves of a textolite plate. Material with a thickness of 3-5 mm is suitable. Grooves are made in the plates for the supply wire.

A little weakness soldering iron - resistor contacts. They are not made of steel, but of copper, unfortunately. Therefore, they have a certain flexibility, and the author of the design speaks about this. So when soldering, don’t press too hard! But if desired and skillful, you can strengthen the fastening by putting two round clamping brackets over the resistor in the contact area, clamping the resistor itself with brackets in this way. And screw their ends to the plates. The brackets can be sealed with fluoroplastic tape.

Well, the finished design!

PEV resistor resistance for soldering iron

For a 40 W soldering iron powered by car battery, the resistance of the resistor should be about 5.1 Ohms (about 30 W of power will be released on it). This takes into account the resistance of the wires (approximately 1 ohm). With this resistance, the soldering iron is normally heated up if the battery voltage is above 12 V and does not overheat at the maximum (14.4 V).

If the soldering iron is supposed to be connected through an automatic temperature regulator (with a thermocouple mounted on the tip), then the resistance of the resistor can be reduced to 3.6...4.7 Ohms. Then it will heat up faster - not 2...3 minutes, but only 40 seconds. And domestic PEVs are practically insensitive to current overloads. For other supply voltages, the resistor resistance should be different, as can be seen from the table.

At 12 volts - necessary tool modern radio electronics in home use. With its help you can quickly solder microcircuits, parts of micro-earphones, handheld electronic watch, fix your phone charger. Many radio amateurs prefer to make an electric soldering iron with their own hands. This work saves money and prevents you from forgetting your school physics course.

Required materials and tools

You don’t need a lot of material to make a soldering iron, and you can easily find it at home. This is copper wire for making a direct soldering base, copper foil, a tin tube (for the casing) and nichrome wire, a handle (preferably plastic), an electrical cord in heat-resistant insulation, silicate glue, talc for electrical insulating mass.

Copper foil can be hard to find. You can use foil fiberglass. It is often used in the manufacture of printed circuits and circuit boards. If you don’t have them at home, you can go to the store and buy them for 200 rubles. required material. To get one sheet of copper foil, you need to heat fiberglass with an ordinary iron and, dividing it into thin plates, pull the corner and wrap it around a round stick.

The main element is a 220/12 volt transformer, through which the soldering iron will receive energy from the mains. TVK-11OL is often used. It can be found in old tube TVs.

The following tools are required:

• tweezers;
• pliers;
• wire cutters;
• plates or boards for coating with adhesive mass;
• stove (electric or gas);
• rags.

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Soldering iron assembly steps

The copper wire you purchased will serve as the tip of the micro-soldering iron. Only 50 mm is needed. It needs to be sharpened in the form of a dihedral angle on one side and the edges must be tinned. The finished tip will be located inside the heating element.

The second stage in the manufacture of a micro-soldering iron will be the preparation of a special electrical insulating mass. To do this, mix talc and liquid glass (silicate glue). Using a board or tweezers, apply the insulation to the cylindrical surface, periodically sprinkling with talcum powder so that the mass does not stick to your hands.

Roll the copper foil into a tube about 35 mm long. This will be the base of the heating element. On one side, the soldering iron tip will be visible from under the tube. This tube must be covered with an insulating mass, as in the first case. The wet mass that you applied must be dried over the stove until it hardens completely. Now you can wind nichrome wire onto the finished base, making a spiral. Its length should not exceed 350 mm. The turns must be laid carefully and very close to each other, while the upper and lower ends of the wire (from 30 to 60 mm) are left as leads. This design Cover it again with the electrical insulation mixture and dry it over the stove.

Now the turning end of the wire needs to be bent back, pressed firmly against the surface of the tube and repeat the application of the mass a third time. Only after this can the heating element of the soldering iron be considered completely ready for use.

The wire that protrudes from under the heating element must be covered with electrical insulating mass. In this case, you need to be patient and, each time applying the mass, do not forget to check the quality of the actions performed.

When the base is completely covered with insulation, you can begin assembling the micro-soldering iron. We connect the ends of the nichrome heater to the handle. To do this, we pull an electrical cord in heat-resistant insulation through the internal plastic cavity. Bare areas need to be insulated with a mixture and dried. After this, we put a protective tin casing on the heater and connect it to the handle. The micro-soldering iron is ready for use.