Homemade miniature low-voltage soldering iron. How to make a soldering iron with your own hands

In many areas of activity, there is a need to ensure strong permanent connections between parts that have the same or different chemical composition. This type of connection includes soldering, which is based on fastening two or more parts using heated solder. The difference in the chemical composition and physical properties of both the parts themselves and the solders used requires different heating temperatures at the joints. Usually soldering is divided into low-temperature and high-temperature. In the first case, it is necessary to ensure that the added solder is heated to a temperature of 450 °C; in the second case, the temperature must be significantly higher than this mark. To implement this technological process, modern manufacturers offer a large number of types of soldering irons. True, such an electrical device as a soldering iron can be made independently at home. The most important thing is to understand the scope of its application, what you plan to solder: microcircuits in electronic equipment or samovars.

Required physical characteristics for a homemade soldering iron

The wide selection of soldering irons on the market today makes it easy to choose a device to solve specific problems. However, many people try to have a homemade soldering iron. To do this, you should consider the required physical characteristics of a homemade soldering iron.

These characteristics are divided into the following quantities:

• voltage supplied to the heating element (for electric soldering irons);
• heating element power;
• the presence of a power regulator;
• the size and shape of the sting;
• solder heating method;
• handle configurations;
• cost.

According to the first parameter, either a standard alternating voltage of 220V, or a constant voltage of 12V, 24V is supplied to the electric soldering iron. The voltage value determines the power of such soldering irons. It has discrete values ​​at 20 W intervals. That is, 40 W, 60 W, 80 W and so on. More advanced devices have a special power regulator for the soldering iron.

The size and shape of the soldering iron tip has a fairly wide range of design solutions. Often, special attachments are used to work with complex radio-electronic devices (for example, for soldering microcircuits, depending on its design).

Modern soldering irons use the following methods for heating solder:

1. Using an electric current applied to a heating element. In this case, the following are used: nichrome wire, ceramic rod, induction coil, pulse converter.
2. Gas apparatus. The solder is heated due to the combustion of the gas jet. You can call it a mini welding machine. Such devices belong to professional equipment.
3. Infrared stations. The solder is heated using infrared radiation. It creates a heating zone from 10 millimeters to 60 millimeters. The size and shape of the heating zone may vary depending on the design of the infrared window.

The most commonly used devices are those that heat the tip using electric current. The small number of elements and the simplicity of the design allow us to say that you can make a soldering iron with your own hands.

The procedure for self-assembly of a soldering iron

The need to have a homemade soldering iron can be dictated by two considerations: the characteristics of existing samples do not meet specific requirements, and the desire to reduce the cost of purchasing a soldering iron. To understand how to make a soldering iron with your own hands, you need to consider its structure.

A typical electric soldering iron includes: a heating element for the soldering iron, a tip, a body, a protective apron, a handle, and a lead wire. All of the listed elements can be made with your own hands or selected from ready-made elements from others, for example, faulty appliances.

Currently, there are a large number of homemade designs of such devices. The most popular are the following:

• changing an existing design or adding necessary parts (for example, changing the diameter of the tip);
• adding a soldering iron heating power regulator;
• homemade micro-soldering iron;
• resistor device.

Changing the design of a soldering iron involves changing the shape of the tip, and thereby reducing the power and time of contact with the part.

There are times when even low-power soldering irons (for example, 25 W or 40 W) are not able to solve the required problem. In this case, a nichrome wire is wound in a spiral onto the finished tip, leaving one end free, as a new tip. Thus, it is possible to significantly reduce the diameter of the tip, which reduces the contact area with the part.

The use of a homemade power regulator in combination makes it possible to obtain improved heating characteristics. In amateur radio literature, you can choose a power regulator circuit based on your requirements, access to the required radio components, and experience in assembling radio devices.

Typically, a thyristor or triac is used as a regulating element. A microcontroller is used to stabilize the output parameter. The choice of body shape remains with the manufacturer. More often, ready-made housings are used: sockets, extension cord housing, housing from a mobile phone power supply, and so on. Therefore, making such a power regulator for a soldering iron yourself is quite simple.

Homemade hammer soldering iron

For soldering large parts, you can make a homemade hammer soldering iron. It received such a specific name due to the tip, which is shaped like a hammer. The power of such a soldering iron can reach 200 watts.

It's not difficult to make. The most important thing is to think over a system for reliable fastening of the tip. Usually it is quite massive. The main problem in manufacturing is the difficulty of finding a blank for the tip.

The simplest miniature soldering iron

For soldering small parts, you can use a micro-soldering iron yourself. To make it, parts from a burning device are used. You will get the simplest miniature soldering iron.

In this case, it is necessary to replace the tip and give it the required configuration. Most often, ordinary copper wire with a diameter of 0.16 mm is used.

Soldering iron with a resistor as a heating element

An interesting design can be implemented using a powerful resistor. With its help, you can make a soldering iron with your own hands. To assemble such a device you will need the following parts:

• Resistor of the PEV series, designed for power up to 10 W, with a rating of 15 to 27 Ohms. It should be taken into account that it will be connected to a 12V or 24V network.
• Copper rod. It will act as a soldering iron tip. It should be taken into account that the outer diameter of the rod must correspond to the inner diameter of the resistor hole. The rod should fit tightly in this hole. You can provide a hole into which a bolt will be screwed to secure the rod.
• A ready-made spiral, which is present in the resistor, is used as a heating element. It is designed for a specific resistance and will provide the necessary dissipation power.
• Power cord with plug.
• Handle for attaching the resistor. It must be made of dielectric material and have high thermal insulating properties. In addition, for convenient operation, the handle must be given an ergonomically sound shape.

If such a device is planned to be used to solve a wide range of problems, it is advisable to connect it to a power regulator.

Soldering iron made from wire resistor

In addition to PEV brand resistors, you can assemble a soldering iron from a wire resistor. Use MLT type resistors. When choosing a resistor, you can calculate the future power of a homemade soldering iron. For example, using a standard 12V power supply and a current of approximately 2.5A, a soldering iron with a power of 30 W is obtained. By decreasing the voltage, the power can be reduced to the required power. For example, with the same circuit parameters, but a voltage of 5V, the power will be 12.5 Watts. This calculation shows that the output is a low-voltage soldering iron, assembled with your own hands. Thus, you can assemble a miniature soldering iron from a non-wire resistor.

This soldering iron can be installed quite easily at home. If everything is done correctly, a soldering iron made from a resistor, assembled with your own hands, will last quite a long time. This technique is usually used to assemble a miniature soldering iron from a non-wire resistor.

Of interest is the homemade design of the so-called pulse soldering iron. Its implementation should be started if you have experience in reading electrical diagrams and experience in their installation and configuration. The advantage of such a soldering iron is its high heating speed (it is 5 seconds). To implement this design, you can use a switching power supply, which is used in fluorescent lamps.

Particular attention should be paid to the area of ​​application. What radio components are planned to be soldered. If these are microcircuits or field-effect transistors, it is necessary to provide for the possibility of grounding the tip. This will remove electrostatic charge and will not lead to breakdown of semiconductor junctions.

Home (and not only) craftsmen are encouraged to assemble a soldering iron with their own hands, first of all, by economic considerations. It is, of course, better to buy a simple 220 V soldering iron for ordinary small soldering work. However, it is also possible to modify it without disassembling it in order to extend the life of the tip. But a 150-200 W “axe”, which can be used to solder metal water pipes, costs not 4.25, but ten times more. And not Soviet rubles, but evergreen conventional units. The same problem arises if you need to solder outside the reach of the power supply from a 12 V car or a pocket lithium-ion battery. How to make a soldering iron yourself for such cases, and not only such, is discussed in today’s publication.

What is smd

Sub Micro Devices, subminiature devices. You can clearly see the SMD by opening your mobile phone, smartphone, tablet or computer. Using SMD technology, tiny (perhaps smaller than the cut of a match) components without wire leads are mounted by soldering onto contact pads, called polygons in SMD terminology. The polygon may have a thermal barrier that prevents heat from spreading along the traces of the printed circuit board. The danger here is not only and not so much in the possibility of the tracks peeling off - the heat may cause the piston connecting the mounting layers to break, which will render the device completely unusable.

A soldering iron for SMD should not only be micro-power, up to 10 W. The heat reserve in its tip should not exceed that which the soldered part can withstand. But long-term soldering with a soldering iron that is too cold is even more dangerous: the solder still doesn’t melt, but the part heats up. And the soldering mode is significantly affected by the outside temperature, and the more, the lower the power of the soldering iron. Therefore, soldering irons for SMD are made either with a limitation of time and/or amount of heat transfer during soldering, or with operational adjustment of the temperature of the tip during the current technological operation. Moreover, you need to keep it 30-40 degrees above the melting temperature of the solder with an accuracy of literally 5-10 degrees; this is the so-called permissible temperature hysteresis of the tip. This is greatly hampered by the thermal inertia of the soldering iron itself, and the main task in designing one is to achieve the lowest heat time constant possible, see below.

It is possible to make a soldering iron at home for any of these purposes. Incl. and powerful for soldering steel or copper water pipes, and a fairly accurate mini for SMD.

Note: Actually, in a soldering iron, the tip is the working (tinned) part of its rod. But, since there are other different rods, for clarity, we will consider the entire rod to be a sting. If the working part of the soldering iron is mounted on a rod, it is called a tip. Let us assume that the tip with the rod is also a sting.

Simplest

Let's not get into the complications for now. Let's say we need a regular 220V soldering iron without any fuss. We go to choose and see that the difference in prices reaches 10 times or more. Let's figure out why. First: heater, nichrome or ceramic. The latter (not “alternative”!) is practically eternal, but if the soldering iron is dropped on a hard floor, it can break. The tip of ceramic soldering irons is necessarily non-replaceable, which means you need to buy a new one. And a nichrome heater, if the soldering iron is not forgotten to be turned on at night, lasts more than 10 years; with occasional use - over 20. And in extreme cases, it can be rewound.

The difference in price has now been reduced to 3-4 times, what else is the matter? In a sting. Nickel-plated copper with special additives is poorly dissolved by solder and burns very slowly in the soldering iron holder, but is expensive. Brass or bronze heats up worse, and it is impossible to solder SMD with it - the temperature hysteresis cannot be brought back to normal due to the thermal conductivity of the material being much worse than that of copper. The red copper tip is eaten by solder and swells quite quickly from copper oxide, but it is cheaper.

Note: a tip made of electrical copper (a piece of winding wire) is unsuitable for a conventional soldering iron - it quickly dissolves and burns. However, for SMD such a sting is just right, its thermal conductivity is the highest possible, and thermal inertia and hysteresis are minimal. True, you will have to change it often, but the sting is about the size of a match or less.

Burning and swelling of the red copper tip can be dealt with simply by being careful: after finishing the work and allowing the soldering iron to cool, take out the tip, peel off the oxide, tapping it on the edge of the table, and blow out the channel of the soldering iron holder. Solder dissolution is worse: sharpening the tip is often inconvenient and it quickly wears out.

You can make a soldering iron tip from ordinary red copper many times more resistant to the action of molten solder by not sharpening its working end, but by forging it to the desired shape. Cold copper can be forged perfectly with an ordinary metalworker's hammer on the anvil of a bench vise. The author of this article has had a forged tip in the ancient Soviet EPSN-25 for more than 20 years, although this soldering iron is in use, if not every day, then certainly every week.

Simple from resistor

Calculation

The simplest soldering iron can be made from a wire resistor; this is a ready-made nichrome heater. It is also easy to calculate: when the rated power is dissipated in free space, the wirewound resistors heat up to 210-250 degrees. With a heat sink in the form of a sting, the “wireworm” maintains a long-term power overload of 1.5-2 times; The temperature of the tip will not be lower than 300 degrees. It can be increased to 400, giving a power overload of 2.5-3 times, but then after 1-1.5 hours of operation the soldering iron will need to be allowed to cool.

Calculate the required resistor resistance using the formula: R = (U^2)/(kP), where:

R – required resistance;

U – operating voltage;

P – required power;

k – the above power overload factor.

For example, you need a 220 V 100 W soldering iron for soldering copper pipes. The heat transfer is large, so we take k = 3. 220^2 = 48400. kP = 3*100 = 300. R = 48400/300 = 161.3... Ohm. We take a 100 W resistor 150 or 180 Ohm, because There are no “wireworms” at 160 Ohms, this rating is from the range of 5% tolerance, and “wireworms” are no more accurate than 10%.

The opposite case: there is a resistor with a power p, what power can you make a soldering iron from it? What voltage should it be powered from? Let's remember: P = U^2/R. Let's take P = 2 p. U^2 = PR. We take the square root of this value and get the operating voltage. For example, there is a 15 W 10 Ohm resistor. The power of the soldering iron is up to 30 W. We take the square root of 300 (30 W * 10 Ohm), we get 17 V. From 12 V, such a soldering iron will develop 14.4 W, you can solder small things with low-melting solder. From 24 V. From 24 V – 57.6 W. The power overload is almost 6 times, but occasionally and for a short time it is possible to solder something large with this soldering iron.

Manufacturing

How to make a soldering iron from a resistor is shown in Fig. higher:

• We select a suitable resistor (item 1, see also below).
• We prepare the parts of the tip and fasteners for it. Use a file to select a groove on the rod for the ring spring. Threaded blind holes are made for the bolt (screw) and the tip, pos. 2.
• We assemble the rod with the tip into the tip, pos. 3.
• We fix the tip in the resistor-heater with a bolt (screw) with a wide washer, pos. 4.
• We attach the heater with the tip to a suitable handle in any convenient way, pos. 5-7. One condition: the heat resistance of the handle is not lower than 140 degrees; the resistor terminals can heat up to this temperature.

Subtleties and nuances

The soldering iron described above made from 5-20 W resistors was made by many (including the author in his pioneer days) and, having tried it, they were convinced that it could not be used seriously. It takes an unbearably long time to heat up, and it only solders small things with a poke - the ceramic layer interferes with the heat transfer from the nichrome spiral to the tip. This is why the heaters of factory soldering irons are wound on mica mandrels - the thermal conductivity of mica is orders of magnitude higher. Unfortunately, it is impossible to roll mica into a tube at home, and rolling 0.02-0.2 mm nichrome is not for everyone either.

But with soldering irons from 100 W (resistors from 35-50 W) the matter is different. The ceramic thermal barrier in them is relatively thinner, on the left in the figure, and the heat reserve in the massive tip is an order of magnitude greater, because its volume grows by the cube of its dimensions. It is quite possible to qualitatively solder a joint of 1/2″ 200 W copper pipes with a resistor soldering iron. Especially if the tip is not prefabricated, but one-piece forged.

Note: wirewound resistors are available for dissipation power up to 160 W.

Only for the soldering iron you need to look for resistors of old types PE or PEV (in the center in the figure, still in production). Their insulation is vitrified and can withstand repeated heating to light red without losing its properties, only darkening as it cools. The ceramic inside is clean. But the resistors C5-35V (on the right in the figure) are painted, and so are the insides. It is completely impossible to remove paint from the channel - ceramics are porous. When heated, the paint becomes charred and the tip sticks tightly.

Soldering iron regulator

The example with a low-voltage soldering iron made from a resistor is given above for good reason. A PE (PEV) resistor from trash or from an iron market most often turns out to be of an inappropriate rating for the current voltage. In this case, you need to make a power regulator for the soldering iron. Nowadays it is much easier even for people who have the vaguest idea about electronics. The ideal option is to buy from the Chinese (well, Ali Express, otherwise) a ready-made universal voltage and current regulator TC43200, see fig. on right; it's inexpensive. Allowable input voltage 5-36 V; output - 3-27 V at a current of up to 5 A. Voltage and current are set separately. Therefore, you can not only set the desired voltage, but also regulate the power of the soldering iron. There is, for example, a 12 V 60 W tool, but now you need 25 W. We set the current to 2.1 A, 25.2 W will go to the soldering iron and not a milliwatt more.

Note: for use with a soldering iron, it is better to replace the standard TC43200 multi-turn regulators with conventional potentiometers with graduated scales.

Pulse

Many people prefer pulse soldering irons: they are better suited for microcircuits and other small electronics (except SMD, but see below). In standby mode, the tip of a pulse soldering iron is either cold or slightly warmed up. Solder by pressing the start button. In this case, the tip quickly, within a fraction of a second, heats up to operating temperature. It is very convenient to control the soldering: the solder has spread, the flux has been squeezed out of a drop, the button has been released, and the tip has cooled just as quickly. You just need to have time to remove it so that it doesn’t get soldered there. With some experience, the danger of burning a component is minimal.

Types and schemes

Pulsed heating of a soldering iron tip is possible in several ways, depending on the type of work and the requirements for workplace ergonomics. In amateur conditions, or for a small individual entrepreneur, a pulse soldering iron will be more convenient and affordable to make one of the traces. schemes:

1. With a current-carrying tip under industrial frequency current;
2. With an isolated tip and forced heating;
3. With a current-carrying tip under high frequency current.

Electrical circuit diagrams of pulsed soldering irons of the indicated types are shown in Fig.: pos. 1 – with a current-carrying tip of industrial frequency; pos. 2 – with forced heating of the insulated tip; pos. 3 and 4 – with a high-frequency current-carrying tip. Next, we will analyze their features, advantages, disadvantages and methods of implementation at home.

50/60 Hz

The circuit of a pulsed soldering iron with a tip under industrial frequency current is the simplest, but this is not its only advantage, and not the main thing. The potential on the tip of such a soldering iron does not exceed a fraction of a volt, so it is safe for the most delicate microcircuits. Until the induction soldering irons of the METCAL system appeared (see below), a significant part of installers in electronics production worked with industrial-frequency pulsers. Disadvantages - bulkiness, significant weight and, as a result, poor ergonomics: shifts last longer than 4 hours. workers got tired and started making mistakes. But there are still a lot of industrial-frequency pulsed soldering irons in amateur use: Zubr, Sigma, Svetozar, etc.

The device of a 50/60 Hz pulse soldering iron is shown in pos. 1 and 2 fig. Apparently, for the sake of saving on production costs, manufacturers most often use transformers on type P cores (magnetic cores) (item 2), but this is far from the optimal option: in order for a soldering iron to solder like EPCN-25, the transformer power needs 60-65 W. Due to the large stray field, the P-core transformer gets very hot in short-circuit mode, and the heating time of the tip reaches 2-4 s.

If the P-core is replaced with an SL from 40 W with a secondary winding made of a copper busbar (items 3 and 4), then the soldering iron can withstand hour-long work with an intensity of 7-8 solderings per minute without unacceptable overheating. To operate in periodic short-term short-circuit mode, the number of turns of the primary winding is increased by 10-15% compared to the calculated one. This design is also advantageous in that the tip (copper wire with a diameter of 1.2-2 mm) can be attached directly to the terminals of the secondary winding (item 5). Since its voltage is a fraction of a volt, this further increases the efficiency of the soldering iron and extends its operating time before overheating.

With forced heating

The circuit diagram of a soldering iron with forced heating does not require any special explanation. In standby mode, the heater operates at a quarter of the rated power, and when you press start, the energy accumulated in the capacitor bank is released into it. By disconnecting/connecting containers to the battery, you can quite roughly, but within acceptable limits, dose the amount of heat generated by the tip. The advantage is the complete absence of induced potential on the tip if it is grounded. Disadvantage: using commercially available capacitors, the circuit can only be implemented for resistor mini-soldering irons, see below. It is used mainly for occasional work on hybrid assembly boards that are not saturated with components, smd + conventional printed circuit boards in through-hole pins.

At high frequency

Pulse soldering irons at high or high frequencies (tens or hundreds of kHz) are very economical: the thermal power at the tip is almost equal to the nameplate electrical power of the inverter (see below). They are also compact and lightweight, and their inverters are suitable for powering constant-heat resistor mini-soldering irons with an insulated tip, see below. Heating the tip to operating temperature in a fraction of a second. Any thyristor voltage regulator 220 V can be used as a power regulator without modifications. They can be powered with a constant voltage of 220 V.

Note: for power over approx. A 50 W HF pulse soldering iron is not worth making. Although, for example Computer power supply units can have a power of up to 350 W or more, but it is almost impossible to make a tip for such power - either it will not warm up to operating temperature, or it will melt on its own.

A serious drawback is that the operating frequencies are affected by the influence of the tip’s own inductance and the secondary winding. Because of this, an induced potential of over 50 V may appear on the tip for a time of more than 1 ms, which is dangerous for CMOS components (CMOS). Another significant drawback is that the operator is exposed to a flow of electromagnetic field (EMF) power. You can work with a pulsed HF soldering iron with a power of 25-50 W for no more than an hour a day, and up to 25 W for no more than 4 hours, but no more than 1.5 hours at a time.

The simplest way of circuit implementation of a 25-30 W pulsed HF soldering iron inverter for ordinary soldering work is based on a 12-volt halogen lamp network adapter, see item. 3 fig. with diagrams. The transformer can be wound on a core of 2 K24x12x6 ferrite rings folded together with a magnetic permeability μ of at least 2000, or on an W-shaped magnetic core made of the same ferrite with a cross-section of at least 0.7 square meters. see Winding 1 - 250-260 turns of enameled wire with a diameter of 0.35-0.5 mm, windings 2 and 3 - 5-6 turns of the same wire. Winding 4 - 2 turns in parallel of wire with a diameter of 2 mm (on a ring) or braid from a television coaxial cable (pos. 3a), also paralleled.

Note: if the soldering iron is more than 15 W, then it is better to replace the MJE13003 transistors with MJE130nn, where nn>03, and put them on radiators with an area of ​​20 square meters or more. cm.

An inverter option for a soldering iron up to 16 W can be made on the basis of a pulse starting device (IPU) for an LDS or the filling of a burnt-out energy-saving light bulb, respectively. power (do not hit the flask, there is mercury vapor!) The modification is illustrated by pos. 4 in Fig. with diagrams. What is highlighted in green may be different in the IPU of different models, but we don’t care about it. We need to remove the starting elements of the lamp (highlighted in red in position 4a) and short-circuit points AA. We get a diagram of the poses. 4b. In it, a transformer is connected in parallel to the phase-shifting inductor L5 on one of the same rings as in the previous one. case or on W-shaped ferrite from 0.5 sq. cm (pos. 4c). Primary winding - 120 turns of wire with a diameter of 0.4-0.7; secondary – 2 turns of wire D>2 mm. The tip (pos. 4g) is made of the same wire. The finished device is compact (item 4d) and can be placed in a convenient case.

Mini and micro on resistors

A soldering iron with a heating element based on an MLT metal film resistor is structurally similar to a soldering iron made from a wire resistor, but is designed for a power of up to 10-12 W. The resistor operates with a power overload of 6-12 times, because, firstly, the heat dissipation through the relatively thick (but absolutely thinner) tip is greater. Secondly, MLT resistors are physically several times smaller than PE and PEV. The ratio of their surface to volume resp. increases and heat transfer to the environment increases relatively. Therefore, soldering irons with MLT resistors are made only in mini and micro versions: when you try to increase the power, the small resistor burns out. Although MLTs for special applications are produced with a power of up to 10 W, it is realistic to make on your own only a soldering iron on the MLT-2 for small discrete components (placers) and small microcircuits, see for example. video below:

Video: micro soldering iron using resistors

Note: the MLT resistor chain can also be used as a heater for a stand-alone cordless soldering iron for ordinary soldering work, see next. video clip:

Video: Cordless mini soldering iron

It is much more interesting to make a mini soldering iron from an MLT-0.5 resistor for smd. The ceramic tube - MLT-0.5 body - is very thin and almost does not interfere with heat transfer to the tip, but will not allow a thermal impulse to pass through at the moment it touches the landfill, which is why SMD components often burn out. Having selected a tip (which requires quite a lot of experience), you can solder SMD with such a soldering iron slowly, continuously monitoring the process through a microscope.

The manufacturing process of such a soldering iron is shown in Fig. Power – 6 W. Heating is either continuous from the inverter described above, or (better) with forced heating with direct current from a 12 V power supply.

Note: how to make an improved version of such a soldering iron with a wider range of applications is described in detail here - oldoctober.com/ru/soldering_iron/

Induction

The induction soldering iron is currently the pinnacle of technical achievements in the field of metal soldering with eutectic solders. In essence, an induction-heated soldering iron is a miniature induction furnace: the HF EMF of the inductor coil is absorbed by the metal of the tip, which is heated by Foucault eddy currents. Making an induction soldering iron with your own hands is not so difficult if you have a source of HF currents at your disposal, for example. computer switching power supply, see e.g. plot

Video: induction soldering iron

However, the quality and economic indicators of induction soldering irons for conventional soldering work are low, which cannot be said about their harmful effects on health. In fact, their only advantage is that the tip stuck to the holder in the body can be torn out without fear of tearing the heater.

Induction mini-soldering irons of the METCAL system are of much greater interest. Their introduction in electronics production made it possible to reduce the percentage of defects due to installer errors by 10,000 times (!) and lengthen the work shift to a normal one, and the workers left after it cheerful and capable in all other respects.

The structure of a METCAL type soldering iron is shown at the top left in Fig. The highlight is the ferronickel coating of the tip. The soldering iron is powered by RF at a precisely maintained frequency of 470 kHz. The thickness of the coating was chosen such that at a given frequency, due to the surface effect (skin effect), Foucault currents were concentrated only in the coating, which gets very hot and transfers heat to the tip. The tip itself turns out to be shielded from EMF and induced potentials do not arise on it.

When the coating warms up to the Curie point, above which the ferromagnetic properties of the coating disappear in temperature, it absorbs EMF energy much weaker, but still does not allow RF into the copper, because maintains electrical conductivity. Having cooled below the Curie point on its own or due to heat transfer to the soldering, the coating again begins to intensively absorb EMF and heats up the tip. Thus, the tip maintains a temperature equal to the Curie point of the coating with an accuracy of literally one degree. The thermal hysteresis of the tip is negligible, because determined by the thermal inertia of the thin coating.

To avoid harmful effects on people, soldering irons are produced with non-replaceable tips, tightly fixed in a cartridge of a coaxial design, through which they are supplied to the RF coil. The cartridge is inserted into the soldering iron handle - a holder with a coaxial connector. Cartridges are available in 500, 600 and 700 types, which correspond to the Curie point of the coating in degrees Fahrenheit (260, 315 and 370 degrees Celsius). Main working cartridge – 600; The 500th is used to solder especially small smds, and the 700th is used to solder large smds and scatterings.

Note: to convert degrees Fahrenheit to Celsius, you need to subtract 32 from Fahrenheit, multiply the remainder by 5 and divide by 9. If you need to do the opposite, add 32 to Celsius, multiply the result by 9 and divide by 5.

Everything is great about METCAL soldering irons, except the price of the cartridge: for “(company name) new, good” – from $40. “Alternative” ones are one and a half times cheaper, but are produced twice as fast. It is impossible to make a METCAL tip yourself: the coating is applied by spraying in a vacuum; Galvanic at the Curie temperature instantly peels off. A thin-walled tube mounted on copper will not provide absolute thermal contact, without which METCAL simply turns into a bad soldering iron. Nevertheless, making an almost complete analogue of the METCAL soldering iron yourself, with a replaceable tip, although difficult, is possible.

Induction for smd

The design of a homemade induction soldering iron for microcircuits and SMD, similar in performance to METCAL, is shown on the right in Fig. Once upon a time, similar soldering irons were used in special production, but METCAL completely replaced them due to better manufacturability and greater profitability. However, you can make such a soldering iron for yourself.

Its secret is in the ratio of the shoulders of the outer part of the tip and the shank protruding from the coil into the inside. If it is as shown in Fig. (approximately), and the shank is covered with thermal insulation, then the thermal focus of the tip will not go beyond the winding. The shank will, of course, be hotter than the tip of the tip, but their temperatures will change synchronously (theoretically, thermohysteresis is zero). Once you have set up the automation using an additional thermocouple that measures the temperature of the tip tip, you can then solder in peace.

The role of the Curie point is played by a timer. It is reset to zero by a signal from the thermostat for heating, for example, by opening the key that shunts the storage tank. The timer is started by a signal indicating the actual start of the inverter operation: the voltage from the additional winding of the transformer of 1-2 turns is rectified and unlocks the timer. If you do not solder with a soldering iron for a long time, the timer will turn off the inverter after 7 seconds until the tip cools down and the thermostat issues a new heating signal. The point here is that the thermal hysteresis of the tip is proportional to the ratio of the times of switched-off and switched-on heating of the tip O/I, and the average power on the tip is proportional to the reverse I/O. Such a system does not maintain the temperature of the tip up to a degree, but it provides +/–25 Celsius with a working tip of 330.

Finally

So what kind of soldering iron should you use? A powerful wirewound resistor is definitely worth it: it costs nothing at all, it doesn’t require eating, but it can help out a lot.

It is also worth making sure that you have a simple soldering iron for SMD from an MLT resistor on your household. Silicon electronics is exhausted, it is at a dead end. The quantum one is already on its way, and the graphene one is clearly looming in the distance. Both do not interface directly with us, like a computer through a screen, mouse and keyboard, or a smart phone/tablet through a screen and sensors. Therefore, silicon frames in future devices will remain, but exclusively SMD, and the current scattering will seem something like radio tubes. And don’t think that this is science fiction: just 30-40 years ago, not a single science fiction writer thought of a smartphone. Although the first samples of mobile phones were already available then. And an iron or a vacuum cleaner “with brains” would never have occurred to the dreamers of that time even in a bad dream.

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How to make a soldering iron with your own hands at home? Today this is quite a pressing issue.

A soldering iron is one of the main tools of a jack-of-all-trades man, along with a hammer, pliers and, of course, a screwdriver.

Of course, soldering irons are different, and their model and functionality differ depending on the purpose.

One type of soldering iron will be needed for the radiator of your car, and a completely different one will easily cope with such everyday tasks as soldering wires when extending them, restoring flying network connectors, etc.

For all this, a small, low-power soldering iron is suitable, just 25-40 watts, which you can make yourself (if you have time and desire).

Its advantage will also be that the quality of such a soldering iron will be an order of magnitude higher than the quality of many consumer goods tools available in retail chains, and the price will be an order of magnitude lower.

Making a small electric soldering iron at home is not particularly difficult.

This tool is useful for working with miniature parts - for example, when soldering various types of microcircuits, electronic watches, and various microelements.

Used in radio electronics; In addition, using a homemade soldering iron you can easily assemble a charger for a mobile phone.

Method number 1. How to make a small soldering iron And how to make a battery-powered soldering iron?

To make an electric soldering iron, we do not need a huge amount of available tools and materials.

All that is needed is a piece of copper wire from which we will make the tip of our soldering iron;

A piece of copper foil, a short length of nichrome wire, and a tin tube (this will serve as the casing of the electric heater).

In addition, you need a heat-resistant plastic handle, a securely insulated electrical cord; ordinary silicate glue and a little talc to create an electrically insulating mass.

Perhaps none of the above, except, perhaps, copper foil, can cause difficulties in acquiring

However, if you were unable to obtain this material, do not despair. Instead of copper foil, foiled fiberglass laminate is quite suitable - the one from which printed circuits and boards are made.

The cost of this material in stores selling radio products is very low (about 200 rubles).

In order to separate the foil from the fiberglass laminate, you need to heat it with an iron: simply hook the edge of the foil, and, following the movement of the iron, wind the foil onto a pre-prepared round rod.

The most important thing is smooth, uniform removal of foil.
Next, we will need electrolyte (gas, of course, is also suitable), ordinary tweezers, pliers, bench pliers, stands for covering parts with adhesive, and a rag for wiping tools and hands.

The power supply for the future electric soldering iron will be an ordinary electrical network, reduced through a 220/12 V converter; the secondary winding of this device must compensate for the electric current of 1A into a 12-ohm load.

For this purpose, we may well be satisfied with the NDR-110K transformer, which is used for the purpose of frame scanning in outdated TVs using tube transistors.

As you understand, we will not need a modern LCD TV.

So, armed with a piece of copper wire, we begin to make a tip for the future miniature soldering iron.

Should be sharpened to the shape of a dihedral angle with radius 40˚ one of the ends of the segment. The edges of the resulting angle, which represent the “cheeks” of the future tip, should be tinned.

The resulting tip will find its application in the heating element of the soldering iron.

The resulting mass must be applied in a thin layer to a cylindrical surface. For this we will use tweezers or a plate as a “brush”.

It should be noted that the mass obtained by kneading is very sticky, and in order to prevent the tool from sticking, it must be sprinkled generously dry talc powder.

Now we’ll “put” a tube (length - 30mm) made of copper foil on our tip.

This will be the basis of our soldering iron heating element (the tip of the tip that will protrude from this tube should be no more than 10 mm long).

The tube must be coated with a thin layer of electrically insulating mass. After this, you need to thoroughly dry it over the gas stove burner (at a temperature of at least 100-150°С) until the electrically insulating mass is completely “sintered”.

So, we have the base of the heating element, which we will wrap with a heating coil made of nichrome wire (length - 350 mm, diameter - 0.2 mm).

This base should be tightened very tightly, turn by turn.

It is important to take into account that the output ends of the wire must be left straight, one – 30 mm long, the other (“turnover”) – 60 mm long.

The winding must be covered with an electrically insulating mass, and again, in the same volume, dried over a fire.

After the insulating layer covering the winding has dried, the long end of the wire must be wrapped back and pressed against the tube.

The result of our activity was the heating element of the electric soldering iron.

The ends of the wire coming out of the heating element should also be covered (50% of the length) with an electrical insulating solution (the free length will subsequently be connected to the cores of the power cord).

This process requires a lot of patience and diligence.

Finally, the last step on the path to creating an electric soldering iron with your own hands is its assembly.

It is necessary to thread a cord in heat-resistant insulation through the heat-resistant handle, and screw the ends of a nichrome electric heater to its bare wires.

The final procedure is another coating and drying.

It is necessary to insulate the exposed ends of the connection between the heating element and the electrical cord. Be careful not to get burned or receive an electric shock.

And finally, we will build our electric heater into a proportionate protective tin case, which we will compatible with the handle. This is followed by a control switching on of the device. This is one of the options for making a miniature soldering iron. To solve other problems, a different device design will be required. Let's look at a number of interesting ideas.

Method number 2. Using a resistor

The most successful and simple solution to the problem of making an electric soldering iron yourself would be to use resistor technology. In this case, you will not need mains voltage. The device will operate in the range from 6 to 24 volts, so power will be provided by both galvanic cells and car batteries. This makes the structure mobile. If the soldering iron is used stationary, then power can be supplied from a regular network through a 220/12V step-down transformer. To make a device with your own hands you will need:

1. A resistor with a power of 7 Watts and a resistance of 20 Ohms.

2. Sheet textolite. It makes a comfortable handle.

3. A circle of copper of various diameters. The larger diameter should match the inner diameter of the hole in the resistor. The smaller rod will serve as the soldering iron tip.

4. Spring corresponding to the outer diameter of the larger rod. Screw and washer.

Making a soldering iron yourself at home involves performing the following operations:

• Drill holes of a larger diameter in the end of the rod and cut a thread to the size of the selected screw. Make a groove according to the thickness of the spring wire. Cut off one ring from the spring; it will serve as a retainer.

• On the other side, in the end of a large diameter rod, drill a hole equal to the outer size of the smaller rod. It will perform the function of a soldering iron tip. To ensure maximum accuracy, it is advisable to perform these works on a lathe. If you don’t have one at hand, you need to show all your skills and knowledge of plumbing.
• Next, we assemble the structure, as shown in the photo.

• We insert the soldering iron rod up to the lock and secure it on the back side with a screw and washer.

• Make a convenient holder from two halves from sheet PCB. To do this, cut out two parts of the same shape. Drill through holes in them for the mounting bolts, then drill holes in one of the plates for the nuts so that they are flush with the surface of the holder. In the inner side of the pads it is necessary to make a selection for the resistor terminals and the supply wire.

• Connect the power wire to the terminals of the heating element.

• Finally assemble the soldering iron and perform a test switch-on.

Another rather exciting idea is the following version of a miniature soldering iron.

Method No. 3. Ballpoint pen - rebirth

Sometimes in the film we see how another agent uses scrap materials to create a unique special tool that can get him out of a seemingly hopeless situation. It turns out that you don’t need to be a super hero to assemble a unique, useful device, a soldering iron, from improvised means in everyday life, which will later help in everyday life.

We use everything that is at hand to construct an electric soldering iron:

1. An ordinary fountain pen.

2. An element with a resistance of 10 Ohms and a power of 0.5 W.

3. A strip of structural materials with electrical insulating properties.

4. Millimeter copper wire.

5. Steel rod with a diameter of 0.8 mm of medium hardness.

6. Power wire.

All this is easy to find in any home workshop. Now a little effort to perform simple DIY soldering iron operations:

• Remove the paint from the resistance element; if this does not work, it is advisable to connect it to a dimmable power source and expose it to heat.
• Take the resistor on one side by cutting, remove the wire and use a drill to make a hole in the end with the diameter of the copper wire. Important! Under no circumstances should the wire come into contact with the resistor cup. Next, you need to countersink the hole with a thicker drill, as shown in the photo. In addition, make a cut on the resistor cup for the current conductor

• Now you need to assemble a soldering iron from a handle. This is a defined elementary operation.

• Place the tip in the prepared place. To avoid burning through the copper wire of the resistor, it is necessary to install a piece of fireproof material between the back wall and the tip as a safety element.

• The final step is to connect the superdevice to a 12 V power supply.

You have managed to assemble a miniature tool with your own hands - an electric soldering iron. The ideas for the following soldering irons are interesting.

Method number 4. High power pulse version

This is a relatively simple electric soldering iron, but to assemble such a model you need to have knowledge in the field of electrical engineering and skills in reading electrical circuits. It was the diagram below that served as the project for creating a powerful impulse model.

This model has the advantage that heating of the working element of the soldering iron occurs within a short time. In just 5 seconds after turning on the power, you can melt solder.

As in the previously proposed options, the main condition is the possibility of making it at home, with your own hands and from scrap materials. In our case, the basis of the future soldering iron will be a modernized switching power supply for a fluorescent lamp. In addition, we will consider other components for our device:

ferrite filter made in the form of a ring from a pulse converter. The primary winding should have 100 - 120 turns of copper wire, 0.5 mm thick, remove the previous secondary winding and independently make one turn of a copper busbar with a diameter of no more than 3.5 mm.

wire with a diameter of 1.5 - 2 mm made of copper for the working element (tip).

Making a soldering iron involves connecting the tip to the secondary winding and the ballast leads to the mains winding of the transformer. That's it, the soldering iron is ready.

Information on how to make a soldering iron stand with a temperature controller with your own hands would be useful. Watch the video

If you need to quickly solder something, in addition to an electric one, you can use a gas soldering iron made from a regular gas lighter, a piece of copper wire and electrical tape. A detailed description of the process is below in the video.

It can be summarized as follows: if you don’t trust electrical equipment manufacturers who flood the market with cheap, low-quality tools, you don’t want to waste your money on it.

What can you do yourself, or are you simply interested in making something with your own hands, namely a soldering iron? By spending a little effort and time, you can easily make a thing “for yourself.”

For your specific purposes and needs, easy to operate and use, which will serve you for a long time and can be easily replaced with a new homemade high-quality tool.

A homemade soldering iron, thanks to the tips and recommendations used here, will serve you for a long time and will allow you to be proud of your own skills and craftsmanship.

Now the question “how to make a soldering iron at home” won't bother you anymore!

You can also watch a video about a DIY super soldering iron

Selected for you:

A soldering iron is an empty phrase for many, but for most men it is an indispensable tool in everyday life. And it doesn’t even matter whether you’re fixing electronics, or whether your inquisitive mind just doesn’t give you rest. In this article we will talk about creating a soldering iron with your own hands from scrap materials. But let’s immediately say that it’s easier to buy, it will be more reliable and safer for your health.

1 ) How to make a soldering iron with your own hands - schematic diagram of a soldering iron

As you can see, the soldering iron is very simple in terms of design and everything you need to assemble it yourself at home can be found in every home.

How to make a soldering iron with your own hands - what you need

Our current soldering iron model will run on a 12-14 volt battery. This is much safer than using a voltage of 220 volts in a homemade soldering iron.

• Li-ion rechargeable battery (quite suitable for a power tool or an old laptop).
• A piece of single-core copper wire with a diameter of about two millimeters and a length of five to six centimeters. We will need it to wind the spiral.
• Heat-resistant fiberglass tubes with different diameters of 3.8 and 1 millimeter to isolate the heating element from the metal casing (you can take it from an electric kettle).
• Nichrome wire with a diameter of 0.3 millimeters (can be taken from an old hair dryer). We will select the length of the wire experimentally depending on the power of the soldering iron and battery.
• A section of a telescopic antenna from a radio receiver with a diameter of 4 millimeters and a length of 3 centimeters.
• A piece of copper single-core wire for the tip, with a diameter of 3.8 millimeters.
• Wire for connecting power to the soldering iron.
• Wooden or plastic tube for the handle.

How to make a soldering iron with your own hands - assembly

• First, we will start making the heating element.
  We wind a nichrome thread around a piece of wire and by selecting the length of the spiral we achieve heating within the range of 300 - 450 degrees Celsius.

• Let's take the same piece of single-core copper wire and put a heat-resistant tube on it.
  We wind the piece of spiral we selected onto the tube.

• We put thinner tubes on the ends of the spiral and place the entire structure inside another, thicker tube. Let's take out the copper wire (it has fulfilled its role and we no longer need it).

• That's it, the heating element is ready. Now all that remains is to insert it inside the copper tube from the antenna and place our tip in it. We fix the tip in the tube with a self-tapping screw.

• Our soldering iron is almost ready. All that remains is to attach the power wire to the ends of the spiral, insert the entire structure into the handle and connect to the power source.

Important: some non-flammable material must be placed between the handle and the antenna tube to avoid a fire. ZMP is quite suitable for this purpose.

Let's summarize all of the above. To create a soldering iron, you do not need any special knowledge or expensive components. But such homemade products should only be done when you need to solder something, but you simply don’t have a soldering iron at hand. And there is simply no time to go shopping to purchase it. In all other cases, it is easier to buy it, especially since it does not cost a lot of money. But in terms of safety, the factory one is much more reliable than any kind of homemade product.

A soldering iron is an attribute of any radio amateur, from a professional to someone who has just started. Today you can find soldering irons or even soldering stations of any size on sale. But they all have one big drawback - they are quite rough and have a long distance from the end of the tip to the edge of the handle. Such dimensions are convenient when soldering large parts, but when working with small elements, such devices are inconvenient due to the fact that they are very heavy position. Having looked at the diagrams of miniature soldering irons on the Internet, I discovered that many of them have some design flaws: a non-replaceable tip, lack of grounding, and much more. So I decided to try to create more modernized“assistant” for a beginning radio amateur based on several instructions. The features of our future soldering iron include: a short distance from the end of the tip to the edge of the handle (~30–40 mm), handle diameter (~15 mm), the ability to replace the tip and heating elements (spare), ease of manufacture, which will not require any special knowledge.

Homemade miniature low-voltage soldering iron - drawing

An ordinary brush was used as a handle, which was previously sanded and varnished.
To secure the wires in the handle well, I used this homemade unit: I made a thread in a hollow rivet and glued it into the handle. Here you can easily fix the cable using a locking screw.
Next I moved on to making mounts for the heat shield. They were also made from hollow rivets, but with a smaller diameter. An M1.6 thread was created in them and the handles were glued into the holes.

The heating element was taken from an ordinary inexpensive Chinese soldering iron; after some manipulations with the dimensions, it fit our device perfectly.

This element has a power of 7 watts and a length of 6.5 mm. Power supply is provided by an adjustable power supply - from 0...18 Volts. In this case, the heating temperature can reach 280 degrees
An ordinary spring was glued into the back of the pen, which can be borrowed from an ordinary ballpoint pen. This part is necessary to protect the power cable from breaking.
The grounding and power wires are threaded into the cambric. A grounding socket is pressed into the main hole of the plug, which is intended for the cable, and the power cables are routed through an additional hole.
As you can see in the picture, the resulting homemade miniature low-voltage soldering iron is barely the same size as an ordinary fountain pen.