When working with a soldering iron, there is often a need to adjust its power. This is necessary when choosing the optimal temperature of the soldering iron tip, since at too low a temperature the solder does not melt well, and at too high a temperature the tip overheats and is destroyed, and the soldering turns out to be of poor quality.
In addition, an amateur often has to perform various tasks using soldering, which require different soldering iron power.
A large number of different circuits are used to regulate power. Examples include:
- with variable resistor;
- with resistor and diode;
- with a microcircuit and a field-effect transistor;
- with a thyristor.
The simplest power regulator for a soldering iron is a circuit with variable resistor. In this option, a variable resistor is connected in series with the soldering iron. The disadvantage of this scheme is that a lot of power is dissipated by the element, which goes into heat. In addition, a high-power variable resistor is a rather scarce element.
More complex is the method using resistor and rectifying diode. In this scheme there are three operating modes. In maximum mode, the soldering iron is connected directly to the network. In operating mode, a resistor is connected in series with the tool, which determines the optimal operating mode.
When turned on in standby mode, the soldering iron is powered through a diode, which cuts off one half-cycle of the AC mains current. As a result, the power of the soldering iron is reduced by half.
Using microcircuit and field effect transistor The power of the soldering iron can be adjusted not only downwards, but also upwards. In this case, the circuit uses a rectifier bridge, the output voltage of which can reach 300 V. In series with , a powerful field-effect transistor of the KP707V2 type is included in the package.
In addition to the temperature controller, the soldering tool itself is assembled from scrap parts. , it's not difficult to learn. You just need to find all the components and follow a certain assembly order.
One of the most common tools for household electrical work is the . Everyone can use it, but there are some nuances when using different types of such screwdrivers.
The power of the soldering iron is controlled pulse width method. To do this, pulses with an average frequency of 30 kHz are supplied to the gate, generated using a multivibrator assembled on a K561LA7 type chip. By changing the generation frequency, you can adjust the voltage on the soldering iron from ten to 300 V. As a result, the current of the tool and its heating temperature change.
The most common option used to adjust the power of a soldering iron is a circuit using thyristor.
It consists of a small number of non-deficient elements, which makes it possible to design such a regulator in very small dimensions.
Features of the most optimal regulator - with a thyristor
A typical thyristor circuit includes the elements shown in the table. 
The power diode VD2 and thyristor VS1 in the circuit are connected in series with the load - a soldering iron. The voltage of one half cycle is directly supplied to the load. The second half-cycle is regulated using a thyristor, the electrode of which receives a control signal.
On transistors VT1, VT2, capacitor C1, resistors R1, R2, a sawtooth voltage circuit is implemented, which is supplied to the control electrode of the thyristor. Depending on the position of the resistance value of the adjusting resistor R2, the opening time of the thyristor changes to pass through the second half-cycle of the alternating voltage.
As a result, there is a change in the average voltage over the period, and, consequently, in power.
Resistor R5 dampens excess voltage, and the zener diode VD1 is designed to provide power to the control circuit. The remaining components are designed to ensure the operating modes of structural elements. To read the characteristics of such devices, use .
DIY device design
As follows from examining the circuit, it consists of a power section, which should be mounted using surface-mounted installation, and a control circuit on a printed circuit board.
Creation printed circuit board includes making the board design. For this purpose, the so-called LUT, which means laser-iron technology, is usually used at home. The PCB manufacturing method includes the following steps:
- creating a drawing;
- transferring the design to the board blank;
- etching;
- cleaning;
- drilling holes;
- tinning of conductors.
To create an image of a board, the Sprint Layout program is most often used. After receiving the design using a laser printer, it is transferred to the foil getinax using a heated iron. Then the excess foil is etched using ferric chloride and the pattern is cleaned. Holes are drilled in the right places and the conductors are tinning. The elements of the control circuit are placed on the board and they are wired (there are certain recommendations -).
Assembly power section The circuit includes connecting resistors R5, R6 and diode VD2 to the thyristor.
Last stage of assembly– placement of the power section and control circuit board in the housing. The order of placement in the housing depends on its type.
In case of installation of open wiring, in order not to be distracted by additional purchases in the store, you can make one. The difference between such devices is only in the functional component - the lighting switching circuit.
You can read more about the features of pass-through switches in. In addition, other types of switches are gaining increasing popularity in modern lighting control systems - for example.
Since the dimensions of the elements are small and there are few of them, you can use, for example, a plastic socket as a housing. The largest place there is occupied by a variable adjustment resistor and a powerful thyristor. However, as experience shows, all the elements of the circuit, together with the printed circuit board, fit into such a case.
Checking and adjusting the circuit
To test the circuit, connect a soldering iron and a multimeter to its output. By rotating the regulator knob, you need to check the smoothness of the change in the output voltage.
An additional element of the regulator can be an LED.
By turning on the LED at the output of the regulator, you can visually determine the increase and decrease in the output voltage by the brightness of the glow. In this case, a limiting resistor must be installed in series with the light source.
conclusions:
- When working with a soldering iron, it is often necessary to adjust its power.
- There are numerous circuits for adjusting the power of a soldering iron with a resistor, transistor, or thyristor.
- The power control circuit of a soldering iron with a thyristor is simple, has small dimensions and can be easily assembled with your own hands.
Video with tips for assembling a soldering iron temperature controller with your own hands
The main regulating element of many circuits is a thyristor or triac. Let's look at several circuits built on this element base.
Option 1.
Below is the first diagram of the regulator, as you can see it probably couldn’t be simpler. The diode bridge is assembled using D226 diodes; a KU202N thyristor with its own control circuits is included in the diagonal of the bridge.
Here is another similar scheme that can be found on the Internet, but we will not dwell on it.
To indicate the presence of voltage, you can supplement the regulator with an LED, the connection of which is shown in the following figure.
You can install a switch in front of the power supply diode bridge. If you use a toggle switch as a switch, make sure that its contacts can withstand the load current.
Option 2.
This regulator is built on a VTA 16-600 triac. The difference from the previous version is that there is a neon lamp in the circuit of the control electrode of the triac. If you choose this regulator, then you will need to choose a neon with a low breakdown voltage, the smoothness of the soldering iron power adjustment will depend on this. A neon light bulb can be cut out of a starter used in LDS lamps. Capacity C1 is ceramic at U=400V. Resistor R4 in the diagram indicates the load, which we will regulate.
The operation of the regulator was checked using a regular table lamp, see photo below.
If you use this regulator for a soldering iron with a power not exceeding 100 W, then the triac does not need to be installed on the radiator.
Option 3.
This circuit is a little more complicated than the previous ones; it contains a logic element (counter K561IE8), the use of which allowed the regulator to have 9 fixed positions, i.e. 9 stages of regulation. The load is also controlled by a thyristor. After the diode bridge there is a conventional parametric stabilizer, from which the power for the microcircuit is taken. Choose diodes for the rectifier bridge such that their power matches the load that you will regulate.
The device diagram is shown in the figure below:
Reference material for the K561IE8 chip:
Diagram of operation of the K561IE8 chip:
Option 4.
Well, the last option, which we will now consider, is how to make a soldering station yourself with the function of regulating the power of the soldering iron.
The circuit is quite common, not complicated, repeated many times by many, no scarce parts, supplemented by an LED that shows whether the regulator is on or off, and a visual control unit for the installed power. Output voltage from 130 to 220 volts.
This is what the assembled regulator board looks like:
The modified printed circuit board looks like this:
The M68501 head was used as an indicator; these used to be used in tape recorders. It was decided to modify the head a little; an LED was installed in the upper right corner, it will show whether it is on/off, and will highlight the small-to-small scale.
The matter was left to the body. It was decided to make it from plastic (foamed polystyrene), which is used for making all kinds of advertisements; it is easy to cut, well processed, glued tightly, and the paint lays down evenly. We cut out the blanks, clean the edges, and glue them with “cosmofen” (glue for plastic).
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.
In order to obtain high-quality and beautiful soldering, it is necessary to correctly select the power of the soldering iron and ensure a certain temperature of its tip, depending on the brand of solder used. I offer several circuits of homemade thyristor temperature controllers for soldering iron heating, which will successfully replace many industrial ones that are incomparable in price and complexity.
Attention, the following thyristor circuits of temperature controllers are not galvanically isolated from the electrical network and touching the current-carrying elements of the circuit is dangerous to life!
To adjust the temperature of the soldering iron tip, soldering stations are used, in which the optimal temperature of the soldering iron tip is maintained in manual or automatic mode. The availability of a soldering station for a home craftsman is limited by its high price. For myself, I solved the issue of temperature regulation by developing and manufacturing a regulator with manual, stepless temperature control. The circuit can be modified to automatically maintain the temperature, but I don’t see the point in this, and practice has shown that manual adjustment is quite sufficient, since the voltage in the network is stable and the temperature in the room is also stable.
Classic thyristor regulator circuit
The classic thyristor circuit of the soldering iron power regulator did not meet one of my main requirements, the absence of radiating interference into the power supply network and the airwaves. But for a radio amateur, such interference makes it impossible to fully engage in what he loves. If the circuit is supplemented with a filter, the design will turn out to be bulky. But for many use cases, such a thyristor regulator circuit can be successfully used, for example, to adjust the brightness of incandescent lamps and heating devices with a power of 20-60 W. That's why I decided to present this diagram.
In order to understand how the circuit works, I will dwell in more detail on the principle of operation of the thyristor. A thyristor is a semiconductor device that is either open or closed. to open it, you need to apply a positive voltage of 2-5 V to the control electrode, depending on the type of thyristor, relative to the cathode (indicated by k in the diagram). After the thyristor has opened (the resistance between the anode and cathode becomes 0), it is not possible to close it through the control electrode. The thyristor will be open until the voltage between its anode and cathode (indicated a and k in the diagram) becomes close to zero. It's that simple.
The classical regulator circuit works as follows. AC mains voltage is supplied through a load (incandescent light bulb or soldering iron winding) to a rectifier bridge circuit made using diodes VD1-VD4. The diode bridge converts alternating voltage into direct voltage, varying according to a sinusoidal law (diagram 1). When the middle terminal of resistor R1 is in the extreme left position, its resistance is 0 and when the voltage in the network begins to increase, capacitor C1 begins to charge. When C1 is charged to a voltage of 2-5 V, current will flow through R2 to the control electrode VS1. The thyristor will open, short-circuit the diode bridge and the maximum current will flow through the load (top diagram).
When you turn the knob of the variable resistor R1, its resistance will increase, the charging current of capacitor C1 will decrease and it will take more time for the voltage on it to reach 2-5 V, so the thyristor will not open immediately, but after some time. The greater the value of R1, the longer the charging time of C1 will be, the thyristor will open later and the power received by the load will be proportionally less. Thus, by rotating the variable resistor knob, you control the heating temperature of the soldering iron or the brightness of the incandescent light bulb.
Above is a classic circuit of a thyristor regulator made on a KU202N thyristor. Since controlling this thyristor requires a larger current (according to the passport 100 mA, the real one is about 20 mA), the values of resistors R1 and R2 are reduced, R3 is eliminated, and the size of the electrolytic capacitor is increased. When repeating the circuit, it may be necessary to increase the value of capacitor C1 to 20 μF.
The simplest thyristor regulator circuit
Here is another very simple circuit of a thyristor power regulator, a simplified version of the classic regulator. The number of parts is kept to a minimum. Instead of four diodes VD1-VD4, one VD1 is used. Its operating principle is the same as the classical circuit. The circuits differ only in that the adjustment in this temperature controller circuit occurs only over the positive period of the network, and the negative period passes through VD1 without changes, so the power can only be adjusted in the range from 50 to 100%. To adjust the heating temperature of the soldering iron tip, no more is required. If diode VD1 is excluded, the power adjustment range will be from 0 to 50%.
If you add a dinistor, for example KN102A, to the open circuit from R1 and R2, then the electrolytic capacitor C1 can be replaced with an ordinary one with a capacity of 0.1 mF. Thyristors for the above circuits are suitable, KU103V, KU201K (L), KU202K (L, M, N), designed for a forward voltage of more than 300 V. Diodes are also almost any, designed for a reverse voltage of at least 300 V.
The above circuits of thyristor power regulators can be successfully used to regulate the brightness of lamps in which incandescent light bulbs are installed. It will not be possible to adjust the brightness of lamps that have energy-saving or LED bulbs installed, since such bulbs have electronic circuits built in, and the regulator will simply disrupt their normal operation. The light bulbs will shine at full power or flicker and this may even lead to their premature failure.
The circuits can be used for adjustment with a supply voltage of 36 V or 24 V AC. You only need to reduce the resistor values by an order of magnitude and use a thyristor that matches the load. So a soldering iron with a power of 40 W at a voltage of 36 V will consume a current of 1.1 A.
Thyristor circuit of the regulator does not emit interference
The main difference between the circuit of the presented soldering iron power regulator and those presented above is the complete absence of radio interference into the electrical network, since all transient processes occur at a time when the voltage in the supply network is zero.
When starting to develop a temperature controller for a soldering iron, I proceeded from the following considerations. The circuit must be simple, easily repeatable, components must be cheap and available, high reliability, minimal dimensions, efficiency close to 100%, no radiated interference, and the possibility of upgrading.
The temperature controller circuit works as follows. The AC voltage from the supply network is rectified by the diode bridge VD1-VD4. From a sinusoidal signal, a constant voltage is obtained, varying in amplitude as half a sinusoid with a frequency of 100 Hz (diagram 1). Next, the current passes through the limiting resistor R1 to the zener diode VD6, where the voltage is limited in amplitude to 9 V, and has a different shape (diagram 2). The resulting pulses charge the electrolytic capacitor C1 through the VD5 diode, creating a supply voltage of about 9 V for the DD1 and DD2 microcircuits. R2 performs a protective function, limiting the maximum possible voltage on VD5 and VD6 to 22 V, and ensures the formation of a clock pulse for the operation of the circuit. From R1, the generated signal is supplied to the 5th and 6th pins of the 2OR-NOT element of the logical digital microcircuit DD1.1, which inverts the incoming signal and converts it into short rectangular pulses (diagram 3). From pin 4 of DD1, pulses are sent to pin 8 of D trigger DD2.1, operating in RS trigger mode. DD2.1, like DD1.1, performs the function of inverting and signal generation (Diagram 4).
Please note that the signals in diagram 2 and 4 are almost the same, and it seemed that the signal from R1 could be applied directly to pin 5 of DD2.1. But studies have shown that the signal after R1 contains a lot of interference coming from the supply network, and without double shaping the circuit did not work stably. And installing additional LC filters when there are free logic elements is not advisable.
The DD2.2 trigger is used to assemble a control circuit for the soldering iron temperature controller and it works as follows. Pin 3 of DD2.2 receives rectangular pulses from pin 13 of DD2.1, which with a positive edge overwrite at pin 1 of DD2.2 the level that is currently present at the D input of the microcircuit (pin 5). At pin 2 there is a signal of the opposite level. Let's consider the operation of DD2.2 in detail. Let's say at pin 2, logical one. Through resistors R4, R5, capacitor C2 will be charged to the supply voltage. When the first pulse with a positive drop arrives, 0 will appear at pin 2 and capacitor C2 will quickly discharge through the diode VD7. The next positive drop at pin 3 will set a logical one at pin 2 and through resistors R4, R5, capacitor C2 will begin to charge.
The charging time is determined by the time constant R5 and C2. The greater the value of R5, the longer it will take for C2 to charge. Until C2 is charged to half the supply voltage, there will be a logical zero at pin 5 and positive pulse drops at input 3 will not change the logical level at pin 2. As soon as the capacitor is charged, the process will repeat.
Thus, only the number of pulses specified by resistor R5 from the supply network will pass to the outputs of DD2.2, and most importantly, changes in these pulses will occur during the voltage transition in the supply network through zero. Hence the absence of interference from the operation of the temperature controller.
From pin 1 of the DD2.2 microcircuit, pulses are supplied to the DD1.2 inverter, which serves to eliminate the influence of the thyristor VS1 on the operation of DD2.2. Resistor R6 limits the control current of thyristor VS1. When a positive potential is applied to the control electrode VS1, the thyristor opens and voltage is applied to the soldering iron. The regulator allows you to adjust the power of the soldering iron from 50 to 99%. Although resistor R5 is variable, adjustment due to the operation of DD2.2 heating the soldering iron is carried out in steps. When R5 is equal to zero, 50% of the power is supplied (diagram 5), when turning at a certain angle it is already 66% (diagram 6), then 75% (diagram 7). Thus, the closer to the design power of the soldering iron, the smoother the adjustment works, which makes it easy to adjust the temperature of the soldering iron tip. For example, a 40 W soldering iron can be configured to run from 20 to 40 W.
Temperature controller design and details
All parts of the thyristor temperature controller are placed on a printed circuit board made of fiberglass. Since the circuit does not have galvanic isolation from the electrical network, the board is placed in a small plastic case of a former adapter with an electrical plug. A plastic handle is attached to the axis of the variable resistor R5. Around the handle on the regulator body, for the convenience of regulating the degree of heating of the soldering iron, there is a scale with conventional numbers.
The cord coming from the soldering iron is soldered directly to the printed circuit board. You can make the connection of the soldering iron detachable, then it will be possible to connect other soldering irons to the temperature controller. Surprisingly, the current consumed by the temperature controller control circuit does not exceed 2 mA. This is less than what the LED in the lighting circuit of the light switches consumes. Therefore, no special measures are required to ensure the temperature conditions of the device.
Microcircuits DD1 and DD2 are any 176 or 561 series. The Soviet thyristor KU103V can be replaced, for example, with a modern thyristor MCR100-6 or MCR100-8, designed for a switching current of up to 0.8 A. In this case, it will be possible to control the heating of a soldering iron with a power of up to 150 W. Diodes VD1-VD4 are any, designed for a reverse voltage of at least 300 V and a current of at least 0.5 A. IN4007 (Uob = 1000 V, I = 1 A) is perfect. Any pulse diodes VD5 and VD7. Any low-power zener diode VD6 with a stabilization voltage of about 9 V. Capacitors of any type. Any resistors, R1 with a power of 0.5 W.
The power regulator does not need to be adjusted. If the parts are in good condition and there are no installation errors, it will work immediately.
The circuit was developed many years ago, when computers and especially laser printers did not exist in nature, and therefore I made a drawing of the printed circuit board using old-fashioned technology on chart paper with a grid pitch of 2.5 mm. Then the drawing was glued with Moment glue onto thick paper, and the paper itself was glued to foil fiberglass. Next, holes were drilled on a homemade drilling machine and the paths of future conductors and contact pads for soldering parts were drawn by hand.
The drawing of the thyristor temperature controller has been preserved. Here is his photo. Initially, the rectifier diode bridge VD1-VD4 was made on a KTs407 microassembly, but after the microassembly was torn twice, it was replaced with four KD209 diodes.
How to reduce the level of interference from thyristor regulators
To reduce interference emitted by thyristor power regulators into the electrical network, ferrite filters are used, which are a ferrite ring with wound turns of wire. Such ferrite filters can be found in all switching power supplies for computers, televisions and other products. An effective, noise-suppressing ferrite filter can be retrofitted to any thyristor regulator. It is enough to pass the wire connecting to the electrical network through the ferrite ring.
The ferrite filter must be installed as close as possible to the source of interference, that is, to the installation site of the thyristor. The ferrite filter can be placed both inside the device body and on its outside. The more turns, the better the ferrite filter will suppress interference, but simply threading the power cable through the ring is sufficient.
The ferrite ring can be taken from the interface wires of computer equipment, monitors, printers, scanners. If you pay attention to the wire connecting the computer system unit to the monitor or printer, you will notice a cylindrical thickening of insulation on the wire. In this place there is a ferrite filter for high-frequency interference.
It is enough to cut the plastic insulation with a knife and remove the ferrite ring. Surely you or someone you know has an unnecessary interface cable from an inkjet printer or an old CRT monitor.
For many experienced radio amateurs, making a power regulator for a soldering iron with your own hands is quite common. For beginners, due to lack of experience, such designs pose a certain difficulty. The main problem is connecting to a 220 V power supply. If there are errors in the circuit or installation, a rather unpleasant effect can occur, accompanied by a loud sound and a power cut. Therefore, in the absence of experience, it is advisable to first purchase a simple device for adjusting power, and after using it and studying it, based on the experience gained, make your own, more advanced one.
An electric soldering iron is a hand-held tool designed to melt solder and heat the parts being joined to the desired temperature.
To prevent emergency situations, a circuit breaker with a small maximum permissible current and one or two sockets should be installed in the workplace. Sockets should be used for the initial connection of manufactured devices. This security measure will allow you to avoid a general shutdown and trips to the control panel, as well as sarcastic comments from family members.
Step power regulator
To manufacture a control device you need to select:
- a 220 V transformer with a power exceeding the power of the soldering iron by 20-25% (the voltage on the secondary winding must be at least 200 V);
- switch for 3-4 positions, more possible. The maximum permissible current of the contacts must correspond to the current consumption of the soldering iron;
- body of the required size;
- cord with plug;
- socket.
You will also need fasteners, screws, screws and nuts. The secondary winding should be rewound, setting the terminals to voltage from 150 to 220 V. The number of terminals will depend on the type of switch; it is desirable to distribute the voltage at the terminals evenly. A switch and voltage indicator can be installed in the power circuit to indicate on/off status.
The device works as follows. If there is power on the primary winding, a voltage of the appropriate magnitude is generated on the secondary winding. Depending on the position of switch S1, the soldering iron will receive voltage from 150 to 220 V. By changing the position of the switch, you can change the heating temperature. If the parts are available, even a beginner can make such a device.
Regulator with smooth power adjustment
This circuit allows you to assemble a compact, small-sized regulator with smooth adjustment of power consumption. The device can be mounted in a socket or in the housing of a mobile phone charger. The device can operate with a load of up to 500 W. For production you will need:
- thyristor KU208G or its analogues;
- diode KR1125KP2, can be replaced with similar diodes;
- a capacitor with a capacity of 0.1 μF with a voltage of at least 160 V;
- resistor 10 kOhm;
- variable resistor 470 kOhm.
The device is quite simple; if there are no assembly errors, it starts working immediately, without additional adjustment. It is advisable to include a voltage indicator and a fuse in the power circuit. The power consumption of the soldering iron is regulated by a variable resistor. A transformer of the required power can be used to regulate the heating temperature of the soldering iron. The best option is to use a device called “LATR”, but such devices have long been discontinued. In addition, they have significant weight and dimensions; they can only be used permanently.
Regulator with temperature control
The device is a thermostat that turns off the load when a specified parameter is reached. The measuring element should be secured to the soldering iron tip. To connect, you need to use a wire in heat-resistant insulation, connect them to a common connector for connecting a soldering iron. You can use separate connections, but this is inconvenient.
Temperature control is carried out by a thermistor KMT-4 or another with similar parameters. The principle of operation is quite simple. Thermal resistance and control resistor are a voltage divider. The variable resistance sets a certain potential at the midpoint of the divider. When heated, the thermistor changes its resistance and, accordingly, changes the set voltage. Depending on the signal level, the microcircuit outputs a control signal to the transistor.
The low-voltage circuit is powered through a limiting resistor and is maintained at the required level by a zener diode and a smoothing electrolytic capacitor. The transistor opens or closes the thyristor with the emitter current. The soldering iron is connected in series with the thyristor.
The maximum permissible power of the soldering iron is no more than 200 W. If you need to use a more powerful soldering iron, you need to use diodes with a higher maximum permissible current for the rectifier bridge, instead of a thyristor - a trinistor. All power elements of the circuit must be installed on heat-removing radiators made of aluminum or copper. The required size for a power of 2 kW for rectifier bridge diodes is at least 70 cm 2, for a trinistor 300 cm 2.
Regulator for a soldering iron on a triac
The most optimal circuit for adjusting the power of a soldering iron is a triac regulator. The soldering iron is connected in series with the triac. All controls operate on the voltage drop of the power control element. The circuit is quite simple and can be performed by radio amateurs with little experience. The value of the control resistor can be changed depending on the required range at the regulator output. With a value of 100 kOhm, you can change the voltage from 160 to 220 V, with 220 kOhm - from 90 to 220 V. At the maximum operating mode of the regulator, the voltage on the soldering iron differs from the mains voltage by 2-3 V, which distinguishes it for the better from devices with thyristors. The voltage change is smooth, you can set any value. The LED in the circuit is intended to stabilize operation, and not as an indicator. It is not recommended to replace or exclude it from the scheme. The device begins to work unstably. If necessary, you can install an additional LED as a voltage indicator with appropriate limiting elements.
For installation, you can use a regular installation box. Installation can be done using a hinged method or a board can be made. To connect a soldering iron, it is advisable to install a socket at the output of the regulator.
When installing a switch in the input circuit, you must use a device with two pairs of contacts that will disconnect both wires. Manufacturing the device does not require significant material costs and can be done quite simply by novice radio amateurs. Adjustment during operation consists of selecting the optimal voltage range for the operation of the soldering iron. This is done by selecting the value of the variable resistor.
The simplest regulator circuit
The simplest temperature controller for a soldering iron can be assembled from a diode with a maximum forward current corresponding to the power of the soldering iron and the switch. The circuit is assembled very simply - the diode is connected in parallel with the contacts of the switch. Operating principle: when the contacts are open, the soldering iron receives only half-cycles of one polarity, the voltage will be 110 V. The soldering iron will have a low temperature. When the contacts are closed, the soldering iron will receive full mains voltage rated at 220 V. The soldering iron will warm up to maximum temperature in a few seconds. This scheme will protect the tool tip from overheating and oxidation and will help significantly reduce energy consumption.
The design can be anything. You can use a manual switch or install a switch with a lever system on a stand. When the tool is lowered onto the stand, the switch should open its contacts, and when raised, close it.