Soldering iron with electronic temperature control. A simple soldering iron temperature regulator. Thermostats: simple and complex

Recently, I have often had to do electronics repairs, on orders, and from friends. He even acquired, for these purposes, to carry an instrument, like any decent TV technician), in Soviet times, a small diplomat. There are several soldering irons available, which have become the standard for many beginners, EPSN 25-40 watts, there is also an EPSN 65 watt soldering iron, with a sharpened tip, for desoldering radio components from massive polygons, such as ATX power supplies, wire harnesses, which are standard EPSN 40 watts, Of course you can do it, but it’s less convenient and quick. For home repairs, there is also a soldering station with a hair dryer. But I wanted to try something new that would satisfy all soldering needs in one person, from lead-free boards, from polygons, and SMD small things.

As everyone usually does in such cases, I turned to the site, so beloved by all radio amateurs and electronics engineers, for its relatively low prices for tools and radio components. Half an hour of searching for the optimal option, in terms of price and configuration, and a rather good-looking soldering iron was found. The price is only about 450 rubles.

The use of a soldering iron ensures high-quality and reliable contact. Quite often, when soldering, the use of different temperature conditions is required, and this task is successfully solved by a soldering iron with temperature control. As a result, elements during the soldering process will no longer be destroyed under the influence of too high voltage. Changes in the operating mode are carried out by switching capacities.

How does a soldering iron work?

Normal operation of a soldering iron is possible if two basic conditions are met: it must melt the solder and maintain the most suitable temperature. It is necessary to take into account the wide range of melting temperature 150-320 0 C, as well as the degree of heat resistance of the elements being connected. With prolonged heating, many parts become inoperative, their insulation properties are reduced or completely lost. Connecting elements with a large area and mass increases the dissipation area of the contacts, so in such cases a power and temperature reserve is required.

Conventional unregulated electric soldering irons are not capable of meeting the conditions required for normal soldering. In this regard, increasing or decreasing the temperature is carried out using a special regulator connected directly to the device. It is based on resistors, due to which changes in temperature, voltage and power occur.

During normal soldering, without using parts sensitive to overheating, the tip of the device on average should heat up 10 0 C above the melting point of the solder, when all of it becomes liquid, and not just some part.
In the case of connecting large contacts, it is not the heating that should be increased, but the power of the soldering iron itself. A device with low power, although it maintains a high temperature, will still not be able to overcome dissipation. Compensation for massive parts is carried out due to the appropriate sizes of the tip, heated by high power.
Before soldering, you need to carefully study the technical data sheet for each radio component, which displays the maximum permissible heating temperature of the housing. It is recommended to change the temperature at which soldering is performed by adjusting the power, rather than simply increasing the degrees. This will reduce the contact of the part with the sting to a minimum. That is, in a short period the solder melts, and the temperature of the case only rises slightly.

Thermostats: simple and complex

The degree of complexity of the design of a particular thermostat for a soldering iron primarily depends on its purpose.

They are available in the following versions:

The simplest ones, operating in two ranges. Switching the temperature of the soldering iron and operating modes occurs in two fixed positions - minimum and maximum. In the first position, the heating of the device is simply maintained in the intervals between operations, and in the second, the soldering process itself is performed.
Devices with dimmers connected to a 220 V network through a break in the cable supplying power. Heating adjustment is carried out due to voltage drops. At the same time, there is a reduction in power, which makes this system ineffective.
The regulator, placed in the housing, is installed in soldering irons with a complex heating circuit. The power supply is also located inside the case along with the regulator. The circuit is considered quite efficient, but does not provide high power for operation.
The design of the remote power supply is one of the most productive and efficient. It can operate from a 220 V network and has adjustments over a wide range. If necessary, the exact temperature value is set. Provides any power.
The most multifunctional device is a soldering station. This device can be used not only at home, but also in other conditions. The station is equipped with a control and monitoring module, as well as a spring holder. Additionally, there are tweezers for ease of working with small parts, a hair dryer for heating the soldering area, a heat emitter that warms up the board before group soldering and other elements.

Types of adjustable soldering irons

All devices, depending on the heater, can be divided into two main types.

A copper soldering iron with temperature control includes a heater consisting of copper wire twisted in the form of a spiral. It works with both direct and alternating current, including low voltage generated by small transformers.

A special thermal sensor is installed on the tip of each device to monitor the temperature of the tip. In fact, it uses physical properties. With the onset of a critical temperature, the sensor begins to signal this. Under the influence of the signal, the power changes or the copper spiral is completely turned off.

Designs of this type are made in different versions. In the simplest modification, the spiral is simply wound onto a dielectric body into which the tip is inserted. In more complex designs of soldering irons, the copper wire is insulated using a special material. Due to this, heat losses are significantly reduced.

No less popular is an adjustable soldering iron with a ceramic heater made in the form of rods. When voltage is applied to them, they heat up. These devices are considered the most modern and easy to use. They heat up very quickly and the temperature is adjustable over a wide range. Correct and careful use guarantees a long service life of the device.

Pros and cons of adjustable soldering irons

Quite often you have to make a choice between copper and ceramic models of soldering irons with temperature control. First of all, it is recommended to study the opinions of professional specialists and reviews of other buyers. However, before making a final decision, you need to independently study the general advantages and disadvantages of these devices.

The main advantages of such soldering irons are the following:

Significant energy savings, increasing the service life of the device.
There is no scale on the tip, which is characteristic of excessive temperatures. Cleaning is required much less frequently, thereby reducing metal wear.
Sensitive radio components will not be damaged, and the current-carrying tracks of the circuit board will not peel off.
Changing the solder does not affect the quality of soldering; overheated fluxes smoke less.
For different jobs, it is not necessary to replace the entire soldering iron. On an adjustable device, it is enough to change the temperature.
The combined use of a thermostat and a power supply provides additional protection against high AC voltage and failure of individual microcircuits under the influence. If necessary, it is possible to modify the soldering iron with temperature control.

The disadvantages include the increased fragility of the main elements, their frequent failure as a result of falling on a hard surface. The design of such soldering irons requires exclusively original tips, which cannot always be quickly found on sale.

To perform high-quality soldering of metal products, during which a reliable connection will be ensured, the home craftsman must have a special tool in his arsenal - a soldering iron with temperature control. After all, you often have to solder parts that differ not only in the material of manufacture, but also in their size. This forces the use of different temperatures during operation, otherwise the parts may not withstand the high voltage and will quickly collapse.

A soldering iron with temperature control can prevent such unpleasant situations. It differs from other similar devices in that it allows you to select the required power at any time and thereby adjust the operating temperature of the soldering iron.

general information

For beginner home craftsmen Those who are going to start soldering should first decide which soldering iron to choose. This has not bothered professionals for a long time, because they know that the most practical option is a soldering iron with temperature settings. This equipment is not only convenient to use, but also has high performance. Knowing the operating features of such a device, you can use it to obtain a very high-quality finished product.

Every novice hobbyist can appreciate such an advantage of a soldering iron as thermal stabilization. Selecting the required temperature of the device is quite simple - to do this, just change the power or voltage values. This option makes it very convenient to work with such a soldering iron, because every professional knows that high-quality soldering of various metal elements is possible only at a certain temperature.

To choose a suitable soldering iron based on temperature, you need to pay attention to the control element used in the device . A good device should have, in addition to the toggle switch, which indicates the maximum and minimum temperature values, and mechanisms with which you can set exact values.

You should also find out how power affects this parameter. If the device is turned on and not used for a long time, this will inevitably lead to overheating of the working tip. During operation, where the amount of heat generated plays a big role, it is necessary that the soldering iron allows you to set the required temperature. If you have no desire to purchase such a device, you can easily make it yourself. All you need for this is a regular dimmer.

For most models, operating power does not exceed 80 W. They operate from a regular household power supply with a voltage of 220 V. To select the required temperature, a special toggle switch is used, which allows you to select the temperature in the range from 200 to 400 degrees Celsius. It provides fairly accurate adjustment with an error of only 10 degrees.

Principle of operation

So, we found out that in order to adjust the operating temperature while using a soldering iron, it must be equipped with a regulator. This device will allow you to independently set not only the required temperature, but also power and voltage. All this can be done using special resistors. When new parameters are established, the tip acquires new properties. One turn of the lever on the regulator allows you to adjust only one of the available parameters.

Types of regulators

Modern soldering irons with power and temperature control can be equipped with various devices for adjusting operating parameters:

If you have such a desire, then you can assemble a ceramic soldering iron with your own hands. It will help you do everything right special electrical circuit.

Low frequency devices

Before you decide to purchase this type of device, you should take into account that its performance characteristics are significantly inferior to most standard devices. The following temperature controllers can be installed on these types of soldering irons:

Copper soldering irons

A special feature of such units is the presence of spirally twisted copper wire in their design. It allows direct and alternating current with low voltage, obtained from small-sized transformers, to pass through itself.

Many soldering irons offered in stores today - electric with temperature control - are often equipped with a temperature sensor installed on the working tip. This device allows you to change the heating temperature of the tip if necessary. Typically, the function of such an element is performed by a thermocouple, the reliability of which cannot be doubted. If the tip heats up up to critical temperatures a corresponding signal is received from the sensor. The copper spiral is instantly activated, which either de-energizes the device or changes the power.

Copper electric soldering irons may differ from each other in design. The simplest option looks like a regular spiral wound around the body. The main requirement that such a device must satisfy is to prevent voltage from passing through it. It also has a working tip.. A more complex version of the device also involves the presence of a copper spiral, additionally insulated with a special material. Using this solution allows one to reduce heat loss by an order of magnitude.

Ceramic heaters

Quite often you can find ceramic-type soldering irons in stores. Among the elements of their design are ceramic rods, which heat up when voltage passes through them. This is a very practical option, which differs from other models in the rapid heating of the working tip and the ability to select a more precise temperature among a wide range of levels. This soldering iron can work very long if used carefully.

Advantages and disadvantages

For many novice home craftsmen, the actual problem is choosing a soldering iron. Not every amateur can understand whether he should buy a ceramic one or whether it would be better to choose a copper soldering iron. Trying to find an answer to the question posed, amateurs turn to reviews from other craftsmen, as well as technical documentation of the devices that interest them. However, first of all, when choosing, you need to take into account the opinion of professionals, since due to their extensive experience in the field of soldering, they can give truly valuable recommendations. First of all, you should consider the advantages and disadvantages of each device.

If we talk about copper soldering irons with a temperature controller, they have the following positive aspects:

Resistance to deformation.
Affordable price.

The disadvantages include the following:

Low durability due to constant overheating of the wire, which burns out quite quickly. However, as statistics show, this most often happens if the device is used for a long time without interruption. If you take pauses during operation, then the manifestation of this shortcoming can be avoided even with a Chinese device.
The tip heats up too slowly when the device is turned on.

Ceramic soldering irons with a thermostat have the following advantages:

Because temperature-controlled ceramic soldering irons have a one-piece design, they will never burn out.
It takes much less time to heat the tip than when using copper soldering irons.
High durability provided the device is used carefully.

At the same time, ceramic soldering irons are not without certain disadvantages:

In case of destruction, the tip can only be replaced with original elements.
They do not tolerate mechanical stress. If the device falls, the ceramic case will not withstand such a strong impact and may crack or even break.

Soldering iron cost

Devices equipped with the ability to adjust the temperature are now offered in many hardware stores. The price for them varies from 1 thousand rubles. up to 6 tr. The cost of such devices may vary depending on the manufacturer, brand and technical characteristics. Let us remember that the weakest element of the structure is the tip. If it fails, purchasing a new element will cost the technician approximately 500 rubles.

Soldering iron with a thyristor power regulator built into the handle.

There is no temperature sensor, and, accordingly, there is no regulator feedback, so this regulator is not a thermostat. However, the ability to adjust the power allows you to control the temperature of the tip and avoid overheating, thereby maintaining the required soldering temperature. Limiting power also helps extend the life of the heater and tip, reducing fading of the protective chrome coating.
Power cable with Euro plug, i.e. there is a possibility of grounding.

The main advantage of the soldering iron is the compatibility of the design of the heating element and tip (tip) with the design of soldering irons used in the most popular soldering stations. These are 900M series tips, or as they are also called differently - HAKKO type tips.
It is the prevalence of these soldering tips that is an undeniable advantage. You can always purchase a tip of the required configuration, and for those who have a soldering station with an already formed set of tips, this soldering iron will be a good addition to the station when soldering work away from the workplace.
Just like in soldering stations, the procedure for changing the soldering tip takes just a few seconds.
Tips 900M - chrome-plated, durable, with factory tinning of the tip. Chrome-plated tips do not require sharpening, and if the operating rules are followed, they have a long service life.

The ergonomic handle makes work comfortable.
Initially, in the factory configuration, the soldering iron is equipped with a conical tip with a tip with a diameter of 0.8 mm (i.e., a 0.8 mm cone).

Characteristics:
- supply voltage: 230V, 50Hz
- power: 60 W
- temperature adjustment range: 200°C - 450°C
- power regulator: yes
- quick-change blades: yes
- tip type: 900M
- grounding plug: yes

Completeness:
- soldering iron with an installed tip - 1 pc.
- stand - 1 piece

Lately I've had to repair a lot of small things. However, doing this with the available EPSN-25 soldering iron was not always convenient.
I ordered and received an inexpensive Chinese soldering iron with temperature control from 200 to 450 degrees.

The soldering iron comes with a set of five tips for performing various types of work (Hakko 900 series replicas).
The declared power of the soldering iron is 60 watts. I was a little disappointed by the length of the wire - 1.38 meters. As for me, the wire is a little short, but everything is individual and depends on the organization of the workplace and the location of the sockets.
Before turning it on, I disassembled the soldering iron and inspected its internal world. The soldering is decent, the triac regulator circuit is (a regular dimmer), there is an indicator LED (it only reports the supply of mains voltage).

There is no thermal sensor, but its presence was not expected for such money. The heating element is stated to be ceramic - there is a characteristic step. However, there is a photo of such a broken heater online. And despite the step, there was nichrome wire inside. So, I can’t say that there is a ceramic heater here. Its resistance is 592 Ohms.

It would seem that everything is not bad, but the very first results were very puzzling. The first acquaintance of the soldering iron with rosin led to the Hollywood appearance of a cloud of smoke and cracking of the rosin throughout its entire depth. The adjustment didn't help much. The soldering iron was put aside until the wattmeter and thermometer arrived. At first I tried to take temperature measurements with an immersion kitchen thermometer, but its measurement limit of 300 degrees and its inertia forced me to refuse its services.

The entire procedure of examining the exterior and inner world, turning it on, calling up the magic smoke, and getting out of the stupor took about 20 minutes. The sting (replica 900M-K), the most massive of the set, after that acquired a very pale appearance and refused to make friends with the tin. IT'S BURNED!!!

Since the parcels arrived three weeks apart, as they arrived, measurements were taken first of power consumption and then of temperature. The photos were taken both at home and in a “house in the village”, so the surrounding background in the photo, although different, was taken with my own hands and the same soldering iron appears in them.
SO:

Upon arrival of the wattmeter, I decided to measure the power consumed by the soldering iron and it turned out that it consumes the declared 60 W only at the moment it is turned on (very difficult to capture with a camera). In this case, the temperature regulator is set to the maximum position. I didn’t install the tip – although there are a lot of them in the set, but still.
The wattmeter reading quickly drops to 40 watts and then drops to 30.1 watts.

Then, after letting the soldering iron cool down, I turned the regulator to minimum and again measured consumption.
At the minimum, the start of consumption also starts from the area of 60 watts, but sharply decreases to 25.2 and finally stabilizes at 20.6 watts.

Please note that heating occurs in the second half of the heater, where the tip is located.

But we solder not by power consumption, but by a tip with a certain temperature, and before the thermometer arrived, the soldering iron went back to the bench.
Upon arrival of the thermometer, I took measurements in the same positions of the regulator - maximum and minimum.
At maximum the temperature reached 587 degrees!!! (They slipped me a burner???)

At a minimum - 276 degrees.

I modified the adjustment circuit by adding another capacitor in parallel to the existing capacitor with a total capacity of 47 nanoFarads * 400 Volts.

So with the power consumption everything is already clear, i.e. it is not critical, so I only took temperature measurements at maximum and minimum and already assembled - with the tip:

At maximum it turned out:

At minimum:

Which borders on the heating level of my usual soldering iron EPSN-25.

There is information on the Internet that the heating element can be unsoldered from the board and pushed forward slightly - this should supposedly increase the heat transfer to the soldering iron tip.

I tried it, but didn’t notice a significant difference - the soldering iron didn’t suffer from underheating anyway. In addition, we must not forget about the linear expansion of materials as a result of heating and with such a modification, when assembled, the heater rests against the cold tip, and when heated, due to linear expansion, the heater may collapse. This is indirectly indicated by the fact that after these tests the nut securing the tip turned out to be quite loose. Therefore, I abandoned this modification and returned the heater to its original state.
For practical testing of the tips, I chose the most massive tip (replica 900M-K). Why him? Mass determines heat capacity, and therefore it will cool more slowly. By the way, all the tips are tinned from the factory and are not magnetic. Those. It’s hard to even call it a replica – it’s a pitiful semblance. Later, the most massive tip used at the beginning of testing was put under a needle file and it can be assumed that the tips are made of copper. However, their weight is confusing; for those made of copper they are quite light, although this is my subjective opinion not based on chemical analysis)).

I didn’t experiment with all the tips, but out of habit I chose a replica 900M-T-3S (round with a bevel). I got used to this tip shape using EPSN-25.
But even here a fiasco awaited - even after modifying the soldering iron, the tip was burned at minimum power. I didn’t even bother installing the rest - they would get burned. The price of the entire set speaks for itself.
Since there was nothing left to lose, I remembered the needle file and mercilessly sharpened the T3S tip using the usual technology. I thought it was all in the bucket, but it turned out that in this form the tip is very friendly with tin and soldering took on a new meaning)). I can’t say how long it will last, but so far I’m happy with the result.
EVENTUALLY:
1. A thing for enthusiasts - it’s unlikely to be used without modification;
2. The tips from the set are garbage;
3. Buying new stings is a lottery) because there are a lot of fakes;
4. The tactile sensations from using the soldering iron are the most positive - it fits like a glove in your hand, thanks to the rubber lining, the grip is firmly fixed and there is no slipping of the hand, heating of the upper part of the handle after an hour of use at a temperature of around 250 degrees (soldered donors) is in the “absent” range to “not significant”;
5. The small distance between the working surface of the tip and the soldering iron handle is a definite plus;
6. Fast heating, low solder consumption, undoubted convenience of soldering SMD components, the ability to change tips for different types of work.

Yes, this is not a professional tool for working every day for 8 hours, but for most radio amateurs who are getting their hands on it, it’s just the thing (taking into account the above).
Another quality that I cannot classify as a disadvantage, but thanks to which it differs from using a conventional low-power soldering iron with a conventional tip - rosin does not linger on the tips of the new soldering iron. Those. By the time you bring it to the board, the tip is already dry. This is due to the small size of the tips included in the kit and, as a consequence, the small surface area.
I got out of the situation using Amtech RMA-223 flux. The soldering turns out perfect. The worst results were shown by the alcohol-rosin mixture.
Considering that you need to get used to each tool, I can say that after the experience gained and the adjustments made, I am generally satisfied with the soldering iron. Let everyone decide for themselves.

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