It has long been known that when a soldering iron overheats, the tip becomes covered with oxides and quickly burns out, especially for cheap Chinese ones. Therefore, we will assemble a good power regulator circuit that will control the degree of its heating.
The main element of the circuit is a powerful triac (symmetric thyristor). It works like a thyristor, but does not have an anode and a cathode, the current can flow in it in both directions. The triac is controlled by a symmetrical dinistor or diac, in this case DB3 (the Soviet analogue of KN 102).
A dinistor can be found in an economy lamp ballast, in an electronic transformer, or bought (it costs a penny). A dinistor can be conditionally called a spark gap. It has a certain breakdown voltage and will open only when this value is reached.
According to the datasheet on DB3, this is an average of 28-30V. With each half-wave of the mains voltage, the capacitor C1 is charged through R1 and R2. When the voltage reaches the breakdown value of the dinistor, it will open and voltage will be applied to the control electrode of the triac. The triac will work (open), the current will flow through the load.
Chain VD1, VD2, C2, R3 is designed for normal operation of the thyristor at minimum output power. The principle of operation of all similar circuits is the same: the longer the thyristor turn-on delay, the lower the output power.
This circuit is different in that it works stably at any output power. By replacing only the thyristor with a more powerful one, you can get a regulator capable of switching a load of tens of kilowatts. For example, last winter I used it with a 5kW heater. If the regulator is used for a soldering iron, then you can do without a heat sink. In case of powerful loads, you will need an appropriate heatsink.
The printed circuit board is compact and can fit in a matchbox, you can assemble the regulator even in the handle of a soldering iron. I assembled it in a small case. By the way, many Chinese industrial soldering irons supplemented with such a simple regulator are announced as a “soldering station”.
List of components
- You can buy a ready-made power regulator
- You can buy a triac
- Dinistor 30pcs for $ 0.85 you can buy
- Diodes 1n4007 100 pieces for $ 0.75 you can buy
Old soldering irons, not equipped with additional functionality, heat to the fullest while the plug is in the network. And disconnected - quickly cool down. An overheated soldering iron can ruin the work: it becomes impossible for them to solder something firmly, the flux evaporates quickly, the tip oxidizes and the solder rolls off it. An insufficiently heated tool can completely ruin the parts, since the solder does not melt well, the soldering iron can be overexposed close to the parts.
To make work more comfortable, you can assemble a soldering iron power regulator with your own hands, which will limit the voltage and thereby prevent the tip from overheating.
Mounting options for soldering iron power regulators
Depending on the type and set of radio components, soldering iron power regulators can be of different sizes, with different functionality. It is possible to assemble both a small simple device in which heating is stopped and resumed by pressing a button, or a large-sized device with a digital indicator and program control.
Depending on the power and tasks, the regulator can be placed in several types of housing. The simplest and most comfortable is a fork. For this, they often use Charger smartphone or case of any adapter. It remains only to find a handle and place it in the wall of the case.
DIY power regulator in the plug
If the body of the soldering iron allows (there is enough space), you can place the board with the parts in it. Such a power regulator is always with the soldering iron - it cannot be forgotten or lost.
Another type of housing for simple regulators is a socket. It can be single:
Do-it-yourself power regulator in a single outlet
or be an extension tee. In the latter, it is very convenient to put a pen with a scale.
Power regulator in a household tee
As you can see, in place of one and sockets there is a switch knob with a scale.
There are also many options for mounting a regulator with a voltage indicator with your own hands. It all depends on the ingenuity of the radio amateur and imagination. This can be either an obvious option - an extension cord with an indicator mounted there, or original solutions.
Power outlet regulator with digital indicator
The counter on the body gives accurate figures for work where a strictly defined temperature is important.
Power regulator in the body of a conventional soap dish
The board is fixed inside with screws.
When installing, you must not forget about the safety rules. Parts must be insulated - for example, with heat shrink tubing.
- See also how to do
Variants of soldering iron power regulator circuits
The power regulator can be assembled according to different schemes. Basically, the differences are in the semiconductor part - a device that will regulate the current supply. It can be a thyristor or triac. To more accurately control the operation of a thyristor or triac, a microcontroller can be added to the circuit.
You can make a simple regulator with a diode and a switch - to leave the soldering iron in working order for some (possibly long) time, preventing it from either cooling down or overheating. The remaining regulators make it possible to set the temperature of the soldering iron tip more smoothly - under various needs. The assembly of the device according to any of the schemes is carried out in a similar way. The photos and videos show examples of how you can assemble a power regulator for a soldering iron with your own hands. Based on them, you can make a device with the variations you personally need and according to your own scheme.
Necessary elements for mounting a do-it-yourself soldering iron power regulator
Thyristor - peculiar electronic key. Passes current in only one direction. Unlike a diode, it has 3 outputs - a control electrode, an anode and a cathode. The thyristor opens by applying a pulse to the electrode. It closes when the direction changes or the current flowing through it stops. Thyristor, its main components and display on the diagrams:
Thyristor
A triac, or triac, is a type of thyristor, only unlike this device, it is bilateral, conducts current in both directions. It is, in fact, two thyristors connected together. The main parts, the principle of operation and the method of display on the diagrams. A1 and A2 - power electrodes, G - control gate:
Triac
Depending on its capabilities, the following radio components are also included in the power regulator circuit for a soldering iron:
Resistor - used to convert voltage to current and vice versa.
The appearance of the resistor and the way it is displayed on the diagram
Capacitor - the main role of this device is that it stops conducting current as soon as it is discharged. And it starts to conduct again as the charge reaches the desired value. In regulator circuits, the capacitor is used to turn off the thyristor.
Capacitor
Diode - a semiconductor, an element that passes current in the forward direction and does not pass in the opposite direction.
Diode
So the diode is indicated on the diagrams:
Diode - designation
A zener diode is a subspecies of a diode, used in voltage stabilization devices.
zener diodes
A microcontroller is a microcircuit that provides electronic control device. There are varying degrees of difficulty.
microcontroller
- See also diagram
Scheme of a soldering iron power regulator with a switch and a diode
This type of regulator is the easiest to assemble, with the fewest parts. It can be collected without a fee, by weight. The switch (button) closes the circuit - all the voltage is applied to the soldering iron, opens it - the voltage drops, the tip temperature too. At the same time, the soldering iron remains heated - this method is good for standby mode. A rectifier diode rated for a current of 1 ampere is suitable.
Circuit with switch and diode
Necessary parts and tools for soldering iron power regulator:
- diode (1N4007);
- switch with button;
- a cable with a plug (this can be a soldering iron cable or an extension cable - if there is a fear of ruining the soldering iron);
- wires;
- flux;
- solder;
- soldering iron;
- Strip and tin wires. Tin the diode.
- Solder the wires to the diode. Remove the excess ends of the diode. Put on heat shrink tubing, heat it up. You can also use an electrical insulating tube - cambric.
- Prepare a cable with a plug in the place where it will be more convenient to mount the switch. Cut the insulation, cut one of the wires inside. Leave part of the insulation and the second wire intact. Strip the ends of the cut wire.
- Place the diode inside the switch: minus the diode - to the plug, plus - to the switch.
- Twist the ends of the cut wire and the wires connected to the diode. The diode must be inside the gap.
- Wires can be soldered. Connect to the terminals, tighten the screws.
- Assemble the switch.
Do-it-yourself power regulator on a thyristor
The thyristor regulator allows you to smoothly set the temperature of the soldering iron from 50 to 100%. To expand this scale (from zero to 100%), a diode bridge must be added to the circuit. The assembly of regulators on both the thyristor and the triac is similar. The method can be applied to any device of this type.
Thyristor regulator
We offer 2 power controller circuits to choose from. The first one is with a low-power thyristor:
Circuit with a low-power thyristor and a light indicator
Small power thyristor - inexpensive, takes up little space. Its feature is increased sensitivity. To control it, a variable resistor and a capacitor are used. Suitable for devices up to 40W. Such a regulator does not require additional cooling.
| Thyristor | VS2 | KU101E |
| Resistor | R6 | SP-04 / 47K |
| Resistor | R4 | SP-04 / 47K |
| Capacitor | C2 | 22 mf |
| Diode | VD4 | KD209 |
| Diode | VD5 | KD209 |
| Indicator | VD6 | - |
The second regulator circuit with a powerful thyristor:
The regulator on the thyristor KU202N
The thyristor is controlled by two transistors. The power level is controlled by resistor R2. The regulator, assembled according to this scheme, is designed for loads up to 100 watts.
Necessary components for DIY assembly:
| Thyristor | VS1 | KU202N |
| Resistor | R6 | 100 kOhm |
| Resistor | R1 | 3.3 kOhm |
| Resistor | R5 | 30 kOhm |
| Resistor | R3 | 2.2 kOhm |
| Resistor | R4 | 2.2 kOhm |
| variable resistor | R2 | 100 kOhm |
| Capacitor | C1 | 0.1uF |
| Transistor | VT1 | KT315B |
| Transistor | VT2 | KT361B |
| zener diode | VD1 | D814V |
| rectifier diode | VD2 | 1N4004 or KD105V |
Assembling a thyristor (triac) power controller on a printed circuit board:
- Make a wiring diagram - outline the convenient location of all the parts on the board. If the board is purchased, the wiring diagram is included.
- Prepare parts and tools: printed circuit board(you need to make it in advance according to the scheme or buy it), radio components, wire cutters, a knife, wires, flux, solder, a soldering iron.
- Place the parts on the board according to the wiring diagram.
- Bite off the excess ends of the parts with wire cutters.
- Lubricate with flux and solder every detail - first resistors with capacitors, then diodes, transistors, thyristor (triac), dinistor.
- Prepare the case for assembly.
- Strip, tin the wires, solder to the board according to the wiring diagram, install the board into the case. Insulate the wire connections.
- Check the regulator - connect to an incandescent lamp.
- Assemble the device.
Scheme of a soldering iron power regulator with a thyristor and a diode bridge
Such a device makes it possible to adjust the power from zero to 100%. The scheme uses a minimum of details. On the right in the diagram is a voltage conversion diagram:
Scheme with a thyristor and a diode bridge
| Resistor | R1 | 42 kOhm |
| Resistor | R2 | 2.4 kOhm |
| Capacitor | C1 | 10 microns x 50 V |
| Diodes | VD1-VD4 | KD209 |
| Thyristor | VS1 | KU202N |
Soldering iron power regulator on a triac
It is not difficult to assemble a triac regulator according to this scheme; installation requires a small number of radio components. The device allows you to adjust the power from zero to 100%. The capacitor and resistor will ensure accurate operation of the triac - it will open even at low power. An LED is used as an indicator.
Necessary radio components for DIY assembly:
| Capacitor | C1 | 0.1uF |
| Resistor | R1 | 4.7 kOhm |
| Resistor | VR1 | 500 kOhm |
| Dinistor | DIAC | DB3 |
| Triac | TRIAC | BT136-600E |
| Diode | D1 | 1N4148/16B |
| Light-emitting diode | LED | - |
The assembly of the triac controller according to the above diagram is presented step by step in the following video:
Power regulator on a triac with a diode bridge
The scheme of such a regulator is not very complicated. In this case, the load power can be varied in a fairly large range. With a power of more than 60 W, it is better to put the triac on the radiator. At lower power, cooling is not needed. The assembly method is the same as in the case of a conventional triac regulator.
Scheme of the regulator on a triac with a diode bridge
An example of mounting a regulator on a triac with a diode bridge on a printed circuit board:
Triac Regulator - PCB Mounting Option
Regulator with triac - example of installation in the case:
Regulator with triac and diode bridge - sample
- You may also need a diagram
Do-it-yourself soldering iron power regulator with a triac on a microcontroller
The microcontroller allows you to accurately set and display the power level, provide automatic shutdown regulator if it is not operated for a long time. The installation method of such a regulator does not differ significantly from the installation of any triac regulator. It is soldered on a printed circuit board, which is prefabricated. Such a regulator can replace a soldering station.
- Another fundamental
Tips for checking and adjusting the power regulator for a soldering iron
Before installation, the assembled regulator can be checked with a multimeter. You need to check only with a connected soldering iron, that is, under load. We rotate the knob of the resistor - the voltage changes smoothly.
In the regulators, assembled according to some of the schemes given here, there will already be indicator lights. They can be used to determine if the device is working. For the rest the most simple check- connect an incandescent bulb to the power regulator. Changing the brightness will clearly reflect the level of the applied voltage.
Regulators where the LED is in series with a resistor (as in the low-power thyristor circuit) can be adjusted. If the indicator is off, you need to choose the value of the resistor - take it with a lower resistance until the brightness is acceptable. Too high brightness cannot be achieved - the indicator will burn out.
As a rule, adjustment with a properly assembled circuit is not required. With the power of a conventional soldering iron (up to 100 W, average power- 40 W) none of the regulators assembled according to the above diagrams requires additional cooling. If the soldering iron is very powerful (from 100 W), then the thyristor or triac must be installed on the radiator to avoid overheating.
Triac with heatsink
You can assemble the power regulator for the soldering iron with your own hands, focusing on your own capabilities and needs. There are many variants of regulator circuits with various power limiters and different controls. Here are just the simplest ones that you can do yourself. Tell in:
In order to get high-quality and beautiful soldering, it is necessary to maintain a certain temperature of the soldering tip, depending on the brand of solder used. I offer a home-made soldering iron heating temperature controller, which can successfully replace many industrial ones that are incomparable in price and complexity.
The main difference between the scheme of the presented soldering iron temperature controller and many existing ones is simplicity and the complete absence of radiating radio interference into the electrical network, since all transients occur at a time when the voltage in the supply network is zero.
Electrical circuit diagrams soldering iron temperature controllers
Attention, the following circuits of temperature controllers are not galvanically isolated from the electric network and touching the current-carrying elements of the circuit is life-threatening!
To adjust the temperature of the soldering iron tip, soldering stations are used in which, manually or automatic mode the optimum temperature of the soldering iron tip is maintained. The availability of a soldering station for the home craftsman is limited by the high price. For myself, I solved the issue of temperature control by developing and manufacturing a regulator with manual smooth 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 enough, since the mains voltage is stable and the room temperature too.
Starting to develop a temperature controller for a soldering iron, I proceeded from the following considerations. The scheme should be simple, easily repeatable, components should be cheap and available, high reliability, minimal dimensions, efficiency close to 100%, no radiating interference, the possibility of modernization.
Classic thyristor regulator circuit
The classic thyristor circuit of the soldering iron temperature controller did not meet one of my main requirements, the absence of radiating interference into the mains and the air. And for a radio amateur, such interference makes it impossible to fully engage in what you love. If the circuit is supplemented with a filter, then the design will turn out to be cumbersome. But for many applications, such a thyristor regulator circuit can be successfully used, for example, to adjust the brightness of incandescent lamps and heating appliances with a power of 20-60 watts. That's why I decided to present this scheme.
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 2-5V to the control electrode, depending on the type of thyristor, relative to the cathode (k is indicated in the diagram). After the thyristor has opened (the resistance between the anode and cathode will become 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 (marked a and k in the diagram) becomes close to zero. It's that simple.
The circuit of the classical regulator works as follows. The mains voltage is supplied through the load (an incandescent bulb or a soldering iron winding) to a rectifier bridge circuit made on VD1-VD4 diodes. The diode bridge converts the alternating voltage into a constant, varying according to a sinusoidal law (diagram 1). When the middle terminal of the resistor R1 is in the leftmost position, its resistance is 0, and when the voltage in the network begins to increase, the capacitor C1 begins to charge. When C1 is charged to a voltage of 2-5V, through R2 the current will go to the control electrode VS1. The thyristor will open, short-circuit the diode bridge and the maximum current will flow through the load (upper diagram). When you turn the knob of the variable resistor R1, its resistance will increase, the charge current of the capacitor C1 will decrease and it will take more time for the voltage across it to reach 2-5V, so the thyristor will not open immediately, but after some time. The larger the value of R1, the longer the charge time for C1, the thyristor will open later and the power received by the load will be proportionally less. Thus, by rotating the knob of the variable resistor, the heating temperature of the soldering iron or the brightness of the incandescent light bulb is controlled.
The simplest thyristor regulator circuit
Here is another of the simplest thyristor power controller circuits, a simplified version of the classic controller. The number of parts is kept to a minimum. Instead of four diodes VD1-VD4, one VD1 is used. Its working principle is the same as classical scheme. The schemes differ only in that the adjustment in this temperature controller circuit occurs only according to the positive period of the network, and the negative period passes through VD1 unchanged, so the power can only be adjusted in the range from 50 to 100%. To adjust the heating temperature of the soldering tip, more is not required. If the VD1 diode is excluded, then the power adjustment range will be from 0 to 50%. 
If a dinistor, for example KN102A, is added to the circuit break from R1 and R2, then the electrolytic capacitor C1 can be replaced with an ordinary one with a capacity of 0.1mF. Thyristors for the above circuits are suitable, KU103V, KU201K (L), KU202K (L, M, N), designed for a forward voltage of more than 300V. Diodes are also almost any, designed for a reverse voltage of at least 300V.
The diagrams above thyristor regulators power can be successfully used to control the brightness of the glow of lamps in which incandescent bulbs are installed. It will not work to adjust the brightness of the glow of lamps in which energy-saving or LED bulbs are installed, since such bulbs have built-in electronic circuits, and the regulator will simply violate them normal work. The bulbs will shine at full power or flash and this may even lead to premature failure.
Schemes can be used to adjust the supply voltage in the network alternating current 36V or 24V. It is only necessary 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 watts at a voltage of 36V will consume a current of 1.1A.
Thyristor regulator circuit does not emit interference
Since the regulators that emitted interference did not suit me, and there was no suitable ready-made temperature controller circuit for the soldering iron, I had to take up the development myself. For more than 5 years, the temperature controller has been working flawlessly. 
The temperature controller circuit works as follows. The voltage from the mains 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). Further, 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 received pulses charge the electrolytic capacitor C1 through the VD5 diode, creating a supply voltage of about 9V for the DD1 and DD2 microcircuits. R2 performs a protective function, limiting the maximum possible voltage on VD5 and VD6 to 22V, and ensures the formation of a clock pulse for the operation of the circuit. With R1, the generated signal is fed to the 5th and 6th outputs 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 the 4th output of DD1, the pulses are fed to the 8th output of the D trigger DD2.1, operating in the RS trigger mode. DD2.1, like DD1.1, also performs the function of inverting and signal conditioning (diagram 4). Please note that the signals in diagram 2 and 4 are almost the same, and it seemed that it was possible to apply a signal from R1 directly to pin 5 of DD2.1. But studies have shown that in the signal after R1 there is a lot of interference coming from the mains, and without double shaping, the circuit did not work stably. And it is not advisable to install additional LC filters when there are free logic elements.
On the DD2.2 trigger, a soldering iron temperature controller control circuit is assembled and it works as follows. Rectangular pulses are received at pin 3 DD2.2 from pin 13 DD2.1, which, with a positive edge, overwrite the level at pin 1 DD2.2, which in this moment present at the D input of the microcircuit (pin 5). At pin 2, the signal is the opposite level. Consider the work of DD2.2 in detail. Let's say on pin 2, a logical unit. Through the resistors R4, R5, the capacitor C2 is charged to the supply voltage. Upon receipt of the first pulse with a positive drop, 0 will appear at pin 2 and capacitor C2 will quickly discharge through diode VD7. The next positive drop at pin 3 will set a logical unit at pin 2 and capacitor C2 will start charging through resistors R4, R5. The charge time is determined by the time constant R5 and C2. The larger R5, the longer it will take C2 to charge. Until C2 is charged to half the supply voltage at pin 5, there will be a logical zero and positive pulse drops at input 3 will not change the logic level at pin 2. As soon as the capacitor is charged, the process will repeat.
Thus, only the number of pulses from the supply network specified by resistor R5 will pass to the outputs of DD2.2, and most importantly, these pulses will fluctuate during the transition of the voltage 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 fed 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 the resistor R5 is variable, the adjustment due to the operation of DD2.2 heating the soldering iron is carried out in steps. With R5 equal to zero, 50% of the power is supplied (diagram 5), when turning through a certain angle it is already 66% (diagram 6), then already 75% (diagram 7). Thus, the closer to the rated power of the soldering iron, the smoother the adjustment works, which makes it easy to adjust the temperature of the soldering tip. For example, a 40W soldering iron can be set to 20W to 40W.
The design and details of the temperature controller
All parts of the temperature controller are located on the printed circuit board. Since the circuit does not have galvanic isolation from the mains, the board is placed in a small plastic box, which is also a plug. A plastic handle is put on the rod of the variable resistor R5. 
The cord from the soldering iron is soldered directly to the PCB. 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 drawn by the temperature controller control circuit does not exceed 2 mA. This is less than the consumption of the LED in the lighting circuit of the light switches. Therefore, the adoption of special measures to ensure temperature regime device is not required.
Chips DD1 and DD2 any 176 or 561 series. Any diodes VD1-VD4, designed for a reverse voltage of at least 300V and a current of at least 0.5A. VD5 and VD7 any impulse. Any low-power zener diode VD6 for a stabilization voltage of about 9V. Capacitors of any type. Any resistors, R1 with a power of 0.5 W. The temperature controller does not need to be adjusted. With serviceable parts and without installation errors, it will work immediately.
Mobile soldering iron
Even people who are “you” with a soldering iron are often stopped by the inability to solder wires due to the lack of an electrical connection. If the soldering place is not far away and it is possible to extend the extension cord, then it is not always safe to work with a soldering iron powered by a 220-volt electrical network in rooms with high humidity and temperature, with conductive floors. For the ability to solder anywhere and safely, I offer a simple version of a stand-alone soldering iron.
Powering the soldering iron from the UPS battery of the computer
By connecting the soldering iron to the battery in the following way, you will not be tied to the electrical network and will be able to solder wherever you need without extension cords in compliance with the requirements of the rules for safe work.
It is clear that in order to solder autonomously, you need a battery with a larger capacity. I immediately remember the car. But it is very heavy, from 12 kg. However, there are other battery sizes, for example, used in uninterruptible power supplies (UPS) computer technology. With a weight of only 1.7 kg, they have a capacity of 7 A * h and give out a voltage of 12 V. Such a battery can be easily transported.
In order to make an ordinary soldering iron mobile, you need to take a plywood plate, drill 2 holes in it with a diameter equal to the thickness of the soldering iron support wire and glue the plate to the battery. When the support is bent, the width of the installation site of the soldering iron must be made slightly smaller than the diameter of the tube with the heat of the soldering iron heater. Then the soldering iron will be inserted with an interference fit, and fixed. It will be convenient to store and transport.
For soldering wires with a diameter of up to 1 mm, a soldering iron designed to operate at a voltage of 12 volts and with a power of 15 watts or more is suitable. The time of continuous operation from a freshly charged soldering iron battery will be more than 5 hours. If you plan to solder wires of a larger diameter, then you should already take a soldering iron with a power of 30 - 40 watts. Then the time of continuous operation will be at least 2 hours.
To power the soldering iron, batteries are quite suitable, which can no longer ensure the normal operation of uninterruptible power supplies due to the loss of their capacity over time. After all, to power a computer, you need a power of 250 watts. Even if the battery capacity has decreased to 1 Ah, it will still ensure the operation of a 30-watt soldering iron for 15 minutes. This time is enough to complete the work of soldering several conductors.
In case of a one-time need to perform soldering, you can temporarily remove the battery from the uninterruptible power supply and return it to its place after soldering.
It remains to install connectors on the ends of the soldering iron wire by pressing or soldering, put them on the battery terminals and the mobile soldering iron is ready for use. Chapter.
A temperature-controlled soldering iron is a power tool necessary for soldering various radio components subject to overheating (transistors, resistors, capacitors, microcircuits, diodes). It is used not only by beginners and experienced radio amateurs, home craftsmen, but also by repair specialists. electronic devices. The popularity of such a power tool, which has recently increased significantly, is explained by its many advantages, the possibility of assembling it yourself.
Design
The simplest instrument of this type with thermoregulation consists of the following parts:
- Housing with a printed circuit board inside - a cylindrical hollow handle made of dense plastic
- Control board - controller located inside the hollow handle;
- Regulator - a resistor with a variable resistance, having a rotating round knob indicating the temperature values;
- LED - an indicator that indicates that the sting has heated up to a predetermined temperature;
- Fixing tube with a nut - a fitting with a sting inserted inside it and a movable nut, with which it is screwed to the body;
- The heating element is a tube on which the sting is put on;
- Fireproof tip - a pre-tinned cone-shaped nozzle with a heat-resistant fireproof coating.
In many modern models of this power tool, the regulator is made in the form of two buttons, the temperature value is indicated on a small monochrome liquid crystal display.
Why increase power?
An increase in power, and therefore, in temperature, is necessary in order to solder radio components that are different in terms of resistance to temperature effects and sizes. So, for soldering small thyristors of small capacitance capacitors, the temperature is much lower than for their larger counterparts.
Principle of operation
Heating and maintaining the set temperature of the tip of such an adjustable soldering iron occur as follows:
- When the device is connected to a power source, current flows to the regulator;
- By changing the resistance of the regulator, a certain power level of the heating element is set, which corresponds to the tip temperature pre-calculated and set during testing of the tool;
- Maintaining a strictly defined tip temperature occurs due to the temperature sensor located inside it - a small thermocouple that prevents the tip from overheating.
Due to the presence of a heating control board, a temperature sensor, in the process of working with such a tool, overheating and overheating of radio components that are very sensitive to elevated temperatures are excluded. In addition, unlike unregulated analogues, such tools are completely protected from phase breakdown to the tip.
Varieties of soldering irons with temperature control
All modern devices used as separate power tools, and as part of soldering stations, depending on the type of heating element and the method of heating the tip, are divided into pulsed, devices with a nichrome and ceramic heater.
Pulse soldering iron
Such a soldering iron is a mains-operated device, while lowering the mains voltage, but increasing the frequency of the current. Such a device does not work all the time, only while pressing the button on the handle. Due to this, it is more economical than analogues of other types, it allows you to solder very small and delicate radio components.
With nichrome heater
The classic nichrome heating element of such a device is a metal tube with fiberglass, mica and numerous turns of thin nichrome wire wound around it. When heated, a wire with high resistance heats up a tube with a copper sting inserted into it.
With ceramic heater
In such devices, the sting is put on a tubular ceramic heating element, which has electrical conductivity and high resistance. With the passage of current, this ceramic tube heats up almost instantly, providing the fastest possible heating of the sting installed on it.
Advantages and disadvantages
A soldering iron with a temperature controller has a number of pros and cons.
The benefits of such a tool include:
- The ability to adjust the temperature;
- Complete elimination of the risk of overheating and damage to radio components sensitive to high temperatures;
- Fast heating;
- Affordable price;
- The presence of a set of fireproof tips in the kit for the device - pre-tinned nozzles with a special non-burning coating.
Among the shortcomings of such devices are:
- Low maintainability;
- The high cost of high-quality semi-professional and professional models;
- The fragility of the ceramic heating element.
Also, the disadvantage of cheap models is a fake ceramic heater, which is a hollow ceramic tube, inside of which there is an asbestos rod wound with thin nichrome wire. Due to the small thickness of the wire, such heaters fail very quickly due to thermostriction - rupture of the wire when it cools.
Heat management
To control heating in such devices, an analog or digital (push-button) thermostat, a temperature sensor in the heating element and a control board are used. In some models and advanced simple soldering irons, temperature control occurs thanks to on-off switches, dimmers, electronic blocks management.
Switches and dimmers
To adjust the temperature of the soldering iron tip, devices such as:
- Switches - two-position toggle switches that allow you to switch the tool to standby or maximum heating mode;
- Dimmers are regulators connected to a wire break with a round, smoothly rotating knob, which allow for very fine adjustment of the degree of heating of the tip.
Control units
The control unit is a control board located separately from the device with an adjustable resistor. Some control units also have a built-in step-down transformer.
The most advanced and multifunctional control units, together with soldering irons connected to them, are such a type of device as soldering stations.
Independent production of power regulators for soldering irons
You can not only purchase a power regulator for a soldering iron, but it is also quite easy to assemble it yourself. Mount it in the break of the network cable of the device in cases from small old electrical appliances. For soldering circuits, perforated copper-plated textolite boards are used.
Below are diagrams of the most commonly assembled thermostats based on such radio components as a variable resistor, triac, thyristor.
From a resistor
The simplest temperature controller for a soldering iron based on a variable resistor is assembled according to the diagram below.
From thyristor
The thyristor-based thermostat board has the following circuit diagram.
From triac
The simplest thermostat on semiconductor parts such as triacs can be assembled according to the following scheme.
Regulator circuits
The soldering iron regulator can be assembled according to two schemes: dimmer and stepped.
dimmer
The dimmer circuit includes one regulator (dimmer) connected to the break in the network cable of the device.
stepped
A do-it-yourself power regulator for a soldering iron in a stepwise scheme involves the installation of an additional controller in a plastic case.
Video
Many soldering irons are sold without a power regulator. When connected to the network, the temperature rises to the maximum and remains in this state. To adjust it, you need to disconnect the device from the power source. In such soldering irons, the flux instantly evaporates, oxides are formed and the tip is in a constantly polluted state. It has to be cleaned frequently. Soldering large components requires high temperatures, while small parts can be burned. To avoid such problems, power regulators are made.
How to make a reliable power regulator for a soldering iron with your own hands
The power controls help control how hot the soldering iron is.
Connecting a ready-made heating power controller
If you do not have the opportunity or desire to mess with the manufacture of the board and electronic components, then you can buy a ready-made power regulator in a radio store or order it on the Internet. The regulator is also called a dimmer. Depending on the power, the device costs 100-200 rubles. You may need to modify it a little after purchase. Dimmers up to 1000 W are usually sold without a cooling radiator.
Power regulator without heatsink
And devices from 1000 to 2000 W with a small heatsink.
Power regulator with small heatsink
And only the more powerful ones are sold with larger heatsinks. But in fact, a dimmer from 500 W should have a small cooling radiator, and from 1500 W large aluminum plates are already installed.
Chinese power regulator with a large heatsink
Keep this in mind when connecting the device. If necessary, install a powerful cooling radiator.
Improved power regulator
For correct connection device to the circuit, look at the reverse side of the printed circuit board. The IN and OUT terminals are indicated there. The input is connected to a power outlet, and the output to a soldering iron.
Designation of input and output terminals on the board
The regulator is mounted different ways. To implement them, you do not need special knowledge, and from the tools you only need a knife, a drill and a screwdriver. For example, you can include a dimmer in a soldering iron power cord. This is the easiest option.
- Cut the soldering iron cable into two pieces.
- Connect both wires to the board terminals. Screw the segment with the fork to the entrance.
- Choose a plastic case that is suitable in size, make two holes in it and install the regulator there.
Another easy way: you can install the regulator and socket on a wooden stand.
Not only a soldering iron can be connected to such a regulator. Now consider a more complex, but compact version.
- Take a large plug from an unnecessary power supply.
- Remove the existing board with electronic components from it.
- Drill holes for the dimmer knob and two terminals for the input plug. Terminals are sold in the radio shop.
- If your regulator has indicator lights, make holes for them too.
- Install the dimmer and terminals into the plug housing.
- Take a portable outlet and plug it in. Insert a plug with a regulator into it.
This device, like the previous one, allows you to connect different devices.
Homemade two-stage temperature controller
The simplest power regulator is a two-stage one. It allows you to switch between two values: the maximum and half of the maximum.
Two stage power regulator
When the circuit is open, current flows through diode VD1. Output voltage 110 V. When the circuit is closed by switch S1, the current bypasses the diode, since it is connected in parallel and the output voltage is 220 V. Select the diode according to the power of your soldering iron. The output power of the regulator is calculated by the formula: P = I * 220, where I is the diode current. For example, for a diode with a current of 0.3 A, the power is calculated as follows: 0.3 * 220 \u003d 66 W.
Since our block consists of only two elements, it can be placed in the body of the soldering iron using surface mounting.
- Solder the parts of the microcircuit in parallel to each other directly using the legs of the elements themselves and the wires.
- Connect to chain.
- Fill everything with epoxy, which serves as an insulator and protection against displacement.
- Make a hole in the handle for the button.
If the case is very small, then use the switch for the lamp. Mount it in the soldering iron cord and insert a diode parallel to the switch.
Light switch
On triac (with indicator)
Consider a simple circuit regulator on a triac and make a printed circuit board for it.
Triac power regulator
PCB manufacturing
Since the circuit is very simple, it makes no sense to install it alone because of it. computer program for electrical circuit processing. Moreover, special paper is needed for printing. And not everyone has laser printer. Therefore, let's go by the simplest way of manufacturing a printed circuit board.
- Take a piece of textolite. Cut off the required size for the chip. Sand the surface and degrease.
- Take a marker for laser discs and draw a diagram on the textolite. In order not to be mistaken, first draw with a pencil.
- Next, let's start etching. You can buy ferric chloride, but after it the sink is poorly washed. If you accidentally drip on clothes, stains will remain that cannot be completely removed. Therefore, we will use a safe and cheap method. Prepare a plastic container for the solution. Pour in 100 ml of hydrogen peroxide. Add half a tablespoon of salt and a sachet of citric acid to 50 g. The solution is made without water. You can experiment with proportions. And always make a fresh solution. Copper should be all etched. This takes about an hour.
- Rinse the board under a stream of well water. Dry. Drill holes.
- Wipe the board with an alcohol - rosin flux or a regular solution of rosin in isopropyl alcohol. Take some solder and tin the tracks.
To apply the scheme to the textolite, you can make it even easier. Draw a diagram on paper. Glue it with adhesive tape to the cut out textolite and drill holes. And only after that draw the circuit with a marker on the board and poison it.
Installation
Prepare all the necessary components for installation:
- solder coil;
- pins in the board;
- triac bta16;
- 100nF capacitor;
- 2 kΩ fixed resistor;
- dinistor db3;
- variable resistor with linear dependence at 500 kOhm.
Proceed with the installation of the board.
- Bite off four pins and solder them to the board.
- Install the dinistor and all other parts except for the variable resistor. Solder the triac last.
- Take a needle and a brush. Clean the gaps between the tracks to remove possible short circuits.
- Take an aluminum radiator to cool the triac. Drill a hole in it. The triac with a free end with a hole will be fixed to an aluminum radiator for cooling.
- Clean the area where the element is attached with fine sandpaper. Take the KPT-8 heat-conducting paste and apply a small amount of paste on the radiator.
- Secure the triac with a screw and nut.
- Gently bend the board so that the triac takes a vertical position with respect to it. To keep the design compact.
- Since all parts of our device are under mains voltage, we will use a handle made of insulating material for adjustment. It is very important. Metal holders are life-threatening here. Put the plastic handle on the variable resistor.
- With a piece of wire, connect the extreme and middle terminals of the resistor.
- Now solder two wires to the extreme conclusions. Connect the opposite ends of the wires to the corresponding terminals on the board.
- Take an outlet. Remove the top cover. Connect two wires.
- Solder one wire from the socket to the board.
- And connect the second to the wire of a two-core network cable with a plug. The power cord has one free core. Solder it to the corresponding pin on the PCB.
In fact, it turns out that the regulator is connected in series to the load power circuit.
Scheme of connecting the regulator to the circuit
If you want to install led indicator into the power regulator, then use a different circuit.
Power Regulator Circuit with LED Indicator
Diodes added here:
- VD 1 - diode 1N4148;
- VD 2 - LED (operation indication).
The triac circuit is too bulky to be included in a soldering iron handle, as is the case with a two-stage regulator, so it must be connected externally.
Installation of the structure in a separate housing
All elements of this device are under mains voltage, so you can not use a metal case.
- Take a plastic box. Outline how the board with the radiator will be placed in it and on which side to connect the power cord. Drill three holes. The two extreme ones are needed to mount the socket, and the middle one is for the radiator. The head of the screw to which the radiator will be attached must be hidden under the socket for electrical safety reasons. The radiator has contact with the circuit, and it has direct contact with the network.
- Make another hole on the side of the case for the network cable.
- Install the radiator mounting screw. WITH reverse side put on the puck. Screw on the radiator.
- Drill an appropriately sized hole for the potentiometer, that is, for the knob of the variable resistor. Insert the part into the body and secure with a regular nut.
- Lay the socket on the case and drill two holes for the wires.
- Fix the socket with two M3 nuts. Insert the wires into the holes and tighten the cover with a screw.
- Route the wires inside the case. Solder one of them to the board.
- The other is to the core of the network cable, which is first inserted into the plastic case of the regulator.
- Insulate the joint with electrical tape.
- Connect the free wire of the cord to the board.
- Close the case with a cap and tighten with screws.
The power regulator is connected to the network, and the soldering iron is connected to the regulator outlet.
Video: installation of a regulator circuit on a triac and assembly in a housing
On thyristor
The power regulator can be made on the bt169d thyristor.
Thyristor power regulator
Circuit components:
- VS1 - thyristor BT169D;
- VD1 - diode 1N4007;
- R1 - 220k resistor;
- R3 - 1k resistor;
- R4 - 30k resistor;
- R5 - resistor 470E;
- C1 - capacitor 0.1mkF.
Resistors R4 and R5 are voltage dividers. They reduce the signal, since the bt169d thyristor is low-power and very sensitive. The circuit is assembled in the same way as a regulator on a triac. Since the thyristor is weak, it will not overheat. Therefore, a cooling radiator is not needed. Such a circuit can be mounted in a small box without an outlet and connected in series with the soldering iron wire.
Power regulator in a small package
Scheme on a powerful thyristor
If in the previous circuit we replace the thyristor bt169d with a more powerful ku202n and remove the resistor R5, then the output power of the regulator will increase. Such a regulator is assembled with a thyristor radiator.
Scheme on a powerful thyristor
On the microcontroller with indication
A simple power regulator with light indication can be made on a microcontroller.
Regulator circuit on the ATmega851 microcontroller
Prepare the following components to assemble it:
Using the S3 and S4 buttons, the power and brightness of the LED will change. The circuit is assembled similarly to the previous ones.
If you want the instrument to show the percentage of output power instead of a simple LED, then use a different circuit and appropriate components, including a numeric indicator.
Regulator circuit on the PIC16F1823 microcontroller
The circuit can be mounted in a socket.
The regulator on the microcontroller in the outlet
Checking and adjusting the thermostat block circuit
Before connecting the unit to the instrument, test it.
- Take the assembled circuit.
- Connect it to the mains cable.
- Connect a 220 lamp to the board and a triac or thyristor. Depending on your schema.
- Plug the power cord into a socket.
- Turn the variable resistor knob. The lamp should change the degree of incandescence.
The circuit with the microcontroller is checked in the same way. Only the digital indicator will still show the percentage of output power.
To adjust the circuit, change the resistors. The more resistance, the less power.
Often you have to repair or modify various devices using a soldering iron. The operation of these devices depends on the quality of soldering. If you purchased a soldering iron without a power regulator, be sure to install it. With constant overheating, not only electronic components but also your soldering iron.
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