REGULATOR FOR SOLDERING IRON

Surely, among beginners in electronics, there are owners of medium and high power soldering irons. In this case, I mean, of course, the power of the soldering iron for soldering electronics. And sometimes these are not grandfather's monsters, with a sting as thick as a little finger, but quite neat EPSN 40 watts. With such soldering irons, if you sharpen the tip under a sharp cone, it is quite convenient to solder transistors, resistors and other output parts, and if necessary, you can even perform one-time work on soldering SMD parts. If not for one but. In such soldering irons, even if their power is only forty watts, the tip temperature is quite high, and when soldering, there is a high probability of overheating semiconductor parts.

In this case, there is no need to buy a new soldering iron with a power of 25 watts; it is enough to assemble a power regulator on a thyristor or triac. I have, for personal use, a power regulator on a KU201L thyristor. The circuit has been working flawlessly for many years, and allows you to adjust the power from half to the maximum. Today I was contacted by a friend who became interested in radio work, and who has just such a soldering iron. It was decided to help the person, and so that the desire to engage in electronics would not be lost due to financial barriers, I agreed to assemble a power regulator. The necessary parts were purchased, costing only about 70 rubles, and proceeded to the assembly. The assembly itself is so elementary that any person who can distinguish a triac from a resistor can solder this regulator. I assembled everything by surface mounting, connecting the parts for twisting, followed by soldering the joints.
Below is a diagram of the regulator:

There are similar circuits, both on thyristors and on triacs. I stopped at this scheme because in it, unlike the one I collected earlier, the power is regulated to zero, and not to half. An acquaintance also expressed the wish that the device, if necessary, could also be used to adjust the brightness of incandescent lamps. Below is a list of parts needed for assembly:

Let's analyze them in more detail:

First of all, we need a triac capable of regulating power up to 300 watts, so that there is a power reserve, and an operating voltage of 400 volts and above. The pinout of the triac can be seen in the figure below:

For beginners who have not previously encountered triacs, I will give its equivalent circuit:

In other words, here we see 2 counter-parallel mounted thyristors, with a common control electrode. The triac must be attached to the radiator by applying thermal paste. Usually I use the domestic KPT-8.

Such a radiator area will be enough for long-term operation of the triac, even with a significant load power, without worrying about its overheating.

When the device is operating, the LED lights up. Any voltage of 2.5 - 3 volts will do. With a variable resistor engine, we adjust the power from zero to maximum. The top terminal of the variable resistor according to the diagram, this will be the leftmost terminal of the resistor if you turn it facing you. The left and middle terminals of the variable resistor must be connected with a jumper. A variable resistor is suitable with a resistance of 470 - 500 KiloOhm, with a linear relationship. Let me remind you that for domestic resistors, the letter A should be in the marking, for imported ones, the letter B (English C).

The diode for the circuit needs a reverse voltage of 400 - 1000 volts, 1 ampere. The capacitor is ceramic, designed to operate at voltages up to 50 volts. Also in the circuit used Dinistor DB3. A resistor is needed of the MLT type, or a similar imported one, for a power of 0.25 watts.

The dinistor has no polarity. Sometimes a dinistor is also called a four-layer diode. Below is its equivalent circuit:

The entire assembly of the regulator took me less than an hour. Pieces of the mounting wire were cut, the leads of the parts were lengthened, twisted and securely soldered. A device made by surface mounting during operation is no less reliable and durable than one made on a printed circuit board, if the installation itself is carried out in good faith. In this form, the device was after soldering:

All exposed leads of the parts were insulated with electrical tape and adhesive tape, in several layers. I left the design in the case to the customer, because the taste and color, as they say. It remains the most elementary to connect the outlet, the cord with the plug and the device can be used. To test the regulator, I applied 220 volts to the input, connecting it with a wire to a plug, and to crocodiles at the other end. A 200 watt lamp was also connected to the output of the regulator with the help of crocodiles. Adjustment was smooth and I was quite satisfied. In five minutes of operation, the thyristor did not have time to heat up, which indicates that the radiator I used will be more than enough to work in conjunction with a soldering iron. Author AKV.

How to make a power regulator for a soldering iron? Do-it-yourself power regulator for a soldering iron: diagrams and instructions

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Build a simple power regulator for a soldering iron in an hour

This article is about how to assemble the simplest power regulator for a soldering iron or other similar load. http://oldoctober.com/

The circuit of such a regulator can be placed in a power plug or in a case from a burnt out or unnecessary small-sized power supply. It will take an hour or two to assemble the device.

related topics.

Introduction.

I made a similar regulator many years ago when I had to earn extra money repairing a radio at a customer's home. The regulator turned out to be so convenient that over time I made another copy, since the first sample permanently settled as an exhaust fan speed regulator. http://oldoctober.com/

By the way, this fan is from the Know How series, as it is equipped with an air shut-off valve of my own design. Construction description >>> The material can be useful for residents living on the upper floors of high-rise buildings and having a good sense of smell.

The power of the connected load depends on the thyristor used and its cooling conditions. If a large thyristor or triac of the KU208G type is used, then you can safely connect a load of 200 ... 300 watts. When using a small thyristor, type B169D, the power will be limited to 100 watts.

How it works?

This is how a thyristor works in an AC circuit. When the strength of the current flowing through the control electrode reaches a certain threshold value, the thyristor is unlocked and locked only when the voltage on its anode disappears.

The triac (symmetric thyristor) works in approximately the same way, only when the polarity on the anode changes, the polarity of the control voltage also changes.

The picture shows what goes where and where it comes out.

In budget control circuits for KU208G triacs, when there is only one power source, it is better to control the "minus" relative to the cathode.

To check the performance of the triac, you can assemble just such a simple circuit. When the contacts of the button are closed, the lamp should go out. If it does not go out, then either the triac is broken, or its breakdown threshold voltage is below the peak value of the mains voltage. If the lamp does not light when the button is pressed, then the triac is broken. The value of the resistance R1 is chosen so as not to exceed the maximum allowable value of the current of the control electrode.

When testing thyristors, a diode must be added to the circuit to prevent reverse voltage.

Schematic solutions.

A simple power regulator can be assembled on a triac or thyristor. I will talk about those and other circuit solutions.

Power regulator on triac KU208G.

HL1 - MH3 ... MH13, etc.

This diagram shows, in my opinion, the simplest and most successful version of the regulator, the control element of which is the KU208G triac. This knob controls the power from zero to maximum.

Assignment of elements.

HL1 - linearizes the control and is an indicator.

C1 - generates a sawtooth pulse and protects the control circuit from interference.

R1 - power regulator.

R2 - limits the current through the anode - cathode VS1 and R1.

R3 - limits the current through HL1 and the control electrode VS1.

Power regulator on a powerful thyristor KU202N.

A similar circuit can be assembled on the KU202N thyristor. Its difference from the triac circuit is that the regulator power adjustment range is 50 ... 100%.

The diagram shows that the limitation occurs only along one half-wave, while the other passes freely through the VD1 diode to the load.

Power regulator on a low-power thyristor.

This circuit, assembled on the cheapest low-power thyristor B169D, differs from the circuit above, only in the presence of resistor R5, which, together with resistor R4, is a voltage divider and reduces the amplitude of the control signal. The need for this is due to the high sensitivity of low-power thyristors. The regulator regulates the power in the range of 50 ... 100%.

Power regulator on a thyristor with an adjustment range of 0 ... 100%.

VD1. VD4-1N4007

In order for the regulator on the thyristor to control power from zero to 100%, you need to add a diode bridge to the circuit.

Now the circuit works similarly to the triac controller.

Construction and details.

The regulator is assembled in the power supply case of the once popular calculator "Electronics B3-36".

The triac and potentiometer are placed on a steel corner made of 0.5 mm thick steel. The angle is screwed to the body with two M2.5 screws using insulating washers.

Resistors R2, R3 and neon lamp HL1 are dressed in an insulating tube (cambric) and fixed by surface mounting on other electrical elements of the structure.

To increase the reliability of fastening the pins of the plug, I had to solder several turns of thick copper wire on them.

This is what power regulators look like, which I have been using for many years.

And this is a 4-second video that allows you to make sure that it all works. The load is a 100 watt incandescent lamp.

Additional material.

Pinout (pinout) of large domestic triacs and thyristors. Thanks to a powerful metal case, these devices can dissipate 1 ... 2 watts of power without a significant change in parameters without an additional radiator.

The pinout of small popular thyristors that can control the mains voltage at an average current of 0.5 Ampere.

admin October 9th, 2011 at 21:38

Look at the instructions for this soldering iron.

Most likely, you have a soldering iron with a thermostat. The basis of such soldering irons and not only soldering irons are solid-state volumetric heating elements with a non-linear characteristic.

The resistance of such an element depends on temperature. When a certain temperature is reached, the resistance of the element begins to increase and the temperature stabilizes.

Structurally, such an element usually has the form of a bar or a cylinder, into which the leads are either pressed, or tightly pressed with special springs. A well-known problem with such elements is a violation of contact.

I have often seen how such thermistors first began to spark under the influence of mains voltage and only then warm up. If this is so, then it is quite possible that he did not have so long to live.

You can try tapping something hard with your finger. If this affects the measured resistance, then there is a solid-state heater. If not, then perhaps there is a primitive thermostat on the active element, which is located in the handle.

Of course, all these are assumptions, since I didn’t hold your soldering iron in my hands.

Why does a soldering iron based on a solid state non-linear element or an active regulator not work in this circuit?

To unlock a thyristor or triac, a certain minimum current is required, called holding current. For KU208N, this is 150mA. And although for real triacs this current can be two to three times less, still 5 mΩ cannot create a current even close in value.

Try to still connect the soldering iron in parallel with the incandescent light bulb 40-60 watts. I ask you for the third time. If it does not work, turn the soldering iron plug over (in case of an active thermostat). Well, that you don’t have a tee at home, really.

If there is a solid-state element (thermistor), then controlling the temperature of such a soldering iron using a triac controller will be more difficult than with a conventional soldering iron with a heater on a nichrome spiral (the range will narrow). Although, it should still work. If there is another active regulator inside, then it is unpredictable.

Alexey October 10th, 2011 at 13:47

I wrote that it works in parallel with the lamp (in the sense that the lighting of the lamp is regulated). I can’t measure the power on the soldering iron (or current / voltage) yet, later I’ll assemble a construction to measure arbitrary current formats =) Works with any plug positions.
In general, I will work, if I see any changes in power, then everything will be fine, and I will write, if not, I will take another soldering iron and try with it. =)

Alexander November 11th, 2011 at 23:00

Please tell me if it is possible in the circuit "Power controller on a thyristor with an adjustment range of 0 ... 100%." instead of BT169D use KU202N? And how much power do you need to take resistors. Conder should be on what voltage.

admin November 11th, 2011 at 23:16

No, you need to do exactly the opposite. A bridge rectifier must be added to the circuit on the KU202N thyristor. If you yourself do not figure out how to do this, then tomorrow I will draw a diagram. Today I published an article - I'm tired.

Resistors any from 0.25 watts and above. Potentiometer 0.5 watt or more. A 400 volt capacitor, but if not, then a lower voltage one can be used. This scheme is from the category of those that, no matter how you collect it, you still get a Kalashnikov.

Alexander November 12th, 2011 at 16:04

Thanks for the answer. I know how to assemble the bridge, only I will install 1N4007 diodes, there are no others, and I’m not going to connect a soldering iron for more than 60 W yet.

Schemes of simple regulators for a soldering iron.

The main regulating element of many circuits is a thyristor or triac. Let's look at several circuits built on this element base.

Below is the first circuit of the regulator, as you can see, it’s probably easier already and nowhere. The diode bridge is assembled on D226 diodes, the KU202N thyristor with its own control circuits is included in the diagonal of the bridge.

Scheme of the soldering iron power regulator on KU202N

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.

Connecting the LED to a 220 volt network

Before the diode bridge for power, you can embed a switch. If you use a toggle switch as a switch, make sure that its contacts can withstand the load current.

This regulator is built on the VTA 16-600 triac. The difference from the previous version is that there is a neon lamp in the control electrode circuit of the triac. If you stop the choice on this regulator, then the neon will need to be selected with a low breakdown voltage, the smoothness of adjusting the power of the soldering iron will depend on this. A neon bulb can be bitten out of a starter used in LDS lamps. Capacitance C1 - ceramic for U=400V. Resistor R4 in the diagram indicates the load, which we will regulate.

Checking the operation of the regulator was carried out using a conventional table lamp, see the photo below.

Checking the operation of the power regulator with a table lamp

If you use this regulator for a soldering iron with a power of not more than 100 W, then the triac does not need to be installed on a radiator.

This scheme is slightly 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 steps of regulation. The thyristor also controls the load. After the diode bridge, there is a conventional parametric stabilizer, from which power is taken for the microcircuit. Diodes for the rectifier bridge, choose such that their power corresponds to the load that you will regulate.

The device diagram is shown in the figure below:

Scheme of a soldering iron power regulator on a thyristor and a K561IE8 chip

Spam material on the K561IE8 chip:

Conclusions of the K561IE8 chip

Table of operation of the K561IE8 chip:

Diagram of the operation of the K561IE8 chip:

Diagram of the operation of the K561IE8 chip

Well, the last option, which we will now consider, is how to make a soldering station yourself with a soldering iron power control function. This scheme was taken from the website of Vladimir Boldyrev. www.fototank.ru

The scheme is quite common, not complicated, repeated by many more than once, no scarce details, supplemented by an LED that shows whether the regulator is on or off, and a visual control unit for installed power. Output voltage from 130 to 220 volts.

Power regulator for soldering station_scheme

This is what the board of the assembled regulator looks like:

Soldering iron power regulator board assembly

The finalized PCB looks like this:

Soldering Station Power Regulator PCB

The M68501 head was used as an indicator, these used to be in tape recorders. It was decided to modify the head a little, an LED was installed in the upper right corner, it will show on / off, and illuminate the scale little by little.

Soldering station indicator

The case is left to the body. It was decided to make it from plastic (expanded polystyrene), which is used to make all kinds of advertisements, it is easy to cut, well processed, glued tightly, the paint lays down evenly. We cut out the blanks, clean the edges, glue them with “cosmofen” (glue for plastic).

Glue Kosmofen for gluing plastic

Appearance of the glued box:

The appearance of the soldering station box

We paint, collect the “offal”, we get something like this:

Appearance of the finished soldering station

Well, in conclusion, if you are going to use soldering irons of different capacities with this regulator, then in the above diagram it is worth replacing the visual control unit with this one:

Scheme of a modified indicator for a soldering station

With the previous version of the indicator circuit (which is without a transistor), the current consumption of the soldering iron was measured, and when soldering irons of different capacities are connected, the readings are different, which is not good.

Instead of an imported diode assembly 1N4007, you can put a domestic one. for example KTS405a.

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Soldering iron power regulator - a variety of options and manufacturing schemes

The temperature of a soldering iron tip depends on many factors.

• Mains input voltage, which is not always stable;
• Heat dissipation in massive wires or contacts on which soldering is performed;
• Ambient air temperatures.

For high-quality work, it is required to maintain the thermal power of the soldering iron at a certain level. On sale there is a large selection of electrical appliances with a temperature controller, but the cost of such devices is quite high.

Even more advanced are soldering stations. In such complexes there is a powerful power supply, with which you can control the temperature and power over a wide range.

The price matches the functionality.
But what if you already have a soldering iron, and you don’t want to buy a new one with a regulator? The answer is simple - if you know how to use a soldering iron, you can make an addition to it.

DIY soldering iron regulator

This topic has long been mastered by radio amateurs who, like no one else, are interested in a quality soldering tool. We offer you several popular solutions with wiring diagrams and assembly order.

Two stage power regulator

This circuit works on devices powered by an AC voltage of 220 volts. In the open circuit of one of the supply conductors, a diode and a switch are connected in parallel to each other. When the switch contacts are closed, the soldering iron is powered in standard mode.

When open, current flows through the diode. If you are familiar with the principle of alternating current flow, the operation of the device will be clear. The diode, passing the current in only one direction, cuts off every second half-cycle, lowering the voltage by half. Accordingly, the power of the soldering iron is halved.

Basically, this power mode is used for long pauses during work. The soldering iron is in standby mode and the tip does not cool much. To bring the temperature to 100% value, turn on the toggle switch - and after a few seconds you can continue soldering. With a decrease in heat, the copper tip oxidizes less, prolonging the life of the device.

Dual-mode circuit on a low-power thyristor

This soldering iron voltage regulator is suitable for low-power devices, not more than 40 watts. For power control, a thyristor KU101E is used (in the diagram - VS2). Despite its compact size and the absence of forced cooling, it practically does not heat up in any mode.

The thyristor is controlled by a circuit of a variable resistor R4 (a conventional SP-04 with a resistance of up to 47K was used) and a capacitor C2 (electrolyte 22uf).

The principle of operation is as follows:

• Standby mode. Resistor R4 is not set to maximum resistance, thyristor VS2 is closed. The soldering iron is powered through the VD4 diode (KD209), reducing the voltage to 110 volts;
• Operating mode with adjustment. In the middle position of the resistor R4, the thyristor VS2 begins to open, partially passing the current through itself. The transition to the operating mode is controlled by the indicator VD6, which lights up when the voltage at the output of the regulator is 150 volts.

Then you can smoothly raise the power, increasing the voltage to 220 volts.
We make a printed circuit board according to the size of the regulator body. In the proposed version, a case from a charger for a mobile phone is used.

The layout is very simple, can be placed in a smaller case. No ventilation is required, the radio components practically do not heat up.

We assemble the device in the case, bring the handle of the resistor out.

A classic Soviet 40 watt soldering iron easily turns into a soldering station that works more stable than all Chinese counterparts.

Triac power regulator

The option also applies to simple circuits designed for low power devices. Actually, an adjustable soldering iron. usually needed to work with microcircuits or SMD components. And in this case, more power will be redundant.

The circuit solution allows you to smoothly adjust the voltage from almost zero to the maximum value. We are talking about 220 volts. The thyristor VS1 (KU208G) serves as a power control element. Element HL-1 (MH13) gives the control graph a linear form and acts as an indicator. Resistor set: R1 - 220k, R2 - 1k, R3 - 300 Ohm. Capacitor C1 - 0.1 microns.

Scheme on a powerful thyristor

If you want to connect a powerful soldering iron to the regulator, the power block diagram is assembled on the KU202N thyristor. With a load of up to 100W, it does not require cooling, so there is no need to complicate the design with a radiator.

The circuit is assembled on an accessible element base, the details can simply be in your storerooms.

Principle of operation:
The supply voltage of the soldering iron is removed from the anode of the thyristor VS1. Actually, this is an adjustable parameter that controls the temperature. The thyristor control circuit is implemented on transistors VT1 and VT2. The control module is powered by the Zener diode VD1 together with the limiting resistor R5.

The output voltage of the control unit is regulated using a variable resistor R2, which actually sets the power parameters of the connected soldering iron.
In the closed state, the thyristor VS1 does not pass current, and the soldering iron does not heat up. When the control resistor R2 rotates, the power supply produces an increasing control voltage, opening the thyristor.

The installation diagram consists of two parts.

It is more convenient to assemble the control unit on an etched board so that its micro-components are grouped without a wired connection.

But the power module of the thyristor and its service elements are located separately, evenly distributed over the body.

"On the knee" the assembled circuit looks like this:

Before packing into the case, we check the performance with a multimeter.

IMPORTANT! The test is performed under load, that is, with a soldering iron connected.

When the resistor R2 is rotated, the voltage at the input to the soldering iron should change smoothly. The circuit is placed in the case of a surface-mounted socket, which makes the design very convenient.

IMPORTANT! It is necessary to securely insulate the components with a heat shrink tube to prevent a short circuit in the socket housing.

The bottom of the socket is closed with a suitable cover. The ideal option is not just a consignment note, but a sealed street outlet. In this case, the first option is chosen.
It turns out a kind of extension cord with a power regulator. It is very convenient to use it, there are no extra devices on the soldering iron, and the regulator knob is always at hand.

Regulator on microcontroller

If you consider yourself an advanced radio amateur, you can assemble a worthy of the best industrial designs, a digital readout voltage regulator. The design is a complete soldering station with two output voltages - a fixed 12 volts and an adjustable 0-220 volts.

The low-voltage unit is implemented on a transformer with a rectifier, and is not particularly difficult to manufacture.

IMPORTANT! When making power supplies with different voltage levels, be sure to install incompatible sockets. Otherwise, you can disable the low-voltage soldering iron by mistakenly connecting it to the 220 volt output.

The variable voltage control unit is made on the PIC16F628A controller.

The details of the circuit and the enumeration of the element base are useless, everything can be seen on the diagram. Power control is performed on the triac VT 136 600. Power supply control is implemented using buttons, the number of gradations is 10. The power level from 0 to 9 is shown on the indicator, which is also connected to the controller.

The clock generator sends pulses to the controller at a frequency of 4 MHz, this is the speed of the control program. Therefore, the controller instantly responds to changes in the input voltage, and stabilizes the output.

The circuit is assembled on a circuit board; such a device cannot be soldered on weight or cardboard.

For convenience, the station can be assembled in a case for radio crafts, or in any other suitable size.

For safety reasons, sockets for 12 and 220 volts are located on different walls of the case. It turned out safe and secure. Such systems have been worked out by many radio amateurs and have proven their efficiency.

As can be seen from the material, you can independently make an adjustable soldering iron with any possibilities and for any wallet.

For a decent quality of soldering work, a home craftsman, and even more so a radio amateur, will need a simple and convenient temperature controller for the soldering tip. For the first time, I saw a device diagram in the Young Technician magazine of the early 80s, and having collected several copies, I still use it.

To assemble the device you will need:
-diode 1N4007 or any other, with a permissible current of 1A and a voltage of 400 - 600V.
- thyristor KU101G.
- electrolytic capacitor 4.7 microfarads with an operating voltage of 50 - 100V.
-resistance 27 - 33 kilo-ohms with a permissible power of 0.25 - 0.5 watts.
- variable resistor 30 or 47 kilo-ohm SP-1, with a linear characteristic.

For simplicity and clarity, I drew the placement and interconnection of parts.

Before assembly, it is necessary to isolate and mold the leads of the parts. We put on insulating tubes 20 mm long on the conclusions of the thyristor, and 5 mm on the leads of the diode and resistor. For clarity, you can use colored PVC insulation, removed from suitable wires, or heat shrink. Trying not to damage the insulation, we bend the conductors, guided by the drawing and photographs.

All parts are mounted on the terminals of a variable resistor, connected to the circuit with four solder points. We put the conductors of the components into the holes on the terminals of the variable resistor, trim everything and solder it. We shorten the conclusions of the radioelements. The positive terminal of the capacitor, the control electrode of the thyristor, the resistance terminal, are connected together and fixed by soldering. The thyristor case is an anode, for safety, we isolate it.

To give the design a finished look, it is convenient to use the case from the power supply with a power plug.

We drill a hole with a diameter of 10 mm on the upper edge of the case. We insert the threaded part of the variable resistor into the hole and fix it with a nut.

To connect the load, I used two connectors with holes for pins with a diameter of 4 mm. On the case we mark the centers of the holes, with a distance between them of 19 mm. In drilled holes with a diameter of 10 mm. insert connectors, fix with nuts. We connect the plug on the case, the output connectors and the assembled circuit, the soldering points can be protected with heat shrink. For a variable resistor, it is necessary to choose a handle made of insulating material of such a shape and size as to cover the axis and nut. We assemble the case, securely fix the regulator knob.

We check the regulator by connecting an incandescent lamp of 20 - 40 watts as a load. Turning the knob, we are convinced of a smooth change in the brightness of the lamp, from half the brightness to full heat.

When working with soft solders (for example, POS-61), soldering iron EPSN 25, 75% of the power is sufficient (the position of the regulator knob is approximately in the middle of the stroke). Important: on all elements of the circuit there is a supply voltage of 220 volts! Electrical safety measures must be followed.

In order for the soldering to be beautiful and of high quality, it is necessary to choose the right power of the soldering iron, to ensure the temperature of the tip. It all depends on the brand of solder. For your choice, I provide several schemes for thyristor temperature regulators of the soldering iron, which can be made at home. They are simple and easy to replace industrial counterparts, besides the price and complexity will be different.

Carefully! Touching the elements of the thyristor circuit can lead to life-threatening injury!

To regulate the temperature of the soldering iron tip, soldering stations are used, which maintain the set temperature in automatic and manual modes. The availability of a soldering station is limited by the size of the wallet. I solved this problem by making a manually adjustable temperature controller. The scheme can be easily modified to automatically maintain the set temperature. But I concluded that manual adjustment is sufficient, since the room temperature and mains current are stable.

Classic thyristor regulator circuit

The classic regulator circuit was bad in that it had radiating noise emitted on the air and the network. These interference interfere with radio amateurs at work. If you modify the circuit by including a filter in it, the size of the structure will increase significantly. But this circuit can also be used in other cases, for example, if it is necessary to adjust the brightness of incandescent lamps or heating appliances, the power of which is 20-60 watts. Therefore, I present this scheme.

To understand how this works, consider the principle of operation of the thyristor. The thyristor is a semiconductor device of a closed or open type. To open it, a voltage equal to 2-5 V is applied to the control electrode. It depends on the selected thyristor, relative to the cathode (letter k in the diagram). The thyristor opened, a voltage equal to zero formed between the cathode and anode. It cannot be closed through the electrode. It will be open until the voltage value of the cathode (k) and the anode (a) is close to zero. Here is such a principle. The circuit works as follows: through the load (the winding of a soldering iron or an incandescent lamp), voltage is applied to the diode bridge of the rectifier, made by diodes VD1-VD4. It serves to convert alternating current into direct current, which changes according to a sinusoidal law (1 diagram). In the leftmost position, the resistance of the middle terminal of the resistor is 0. When the voltage increases, the capacitor C1 is charged. When the voltage of C1 is 2-5 V, current will flow to VS1 through R2. In this case, the thyristor will open, the diode bridge will short-circuit, the maximum current will pass through the load (diagram above). If you turn the knob of the resistor R1, there will be an increase in resistance, the capacitor C1 will charge longer. Therefore, the opening of the resistor will not happen immediately. The more powerful R1, the longer it will take to charge C1. By turning the knob to the right or left, you can adjust the temperature of the soldering iron tip.

The photo above shows the regulator circuit assembled on the KU202N thyristor. In order to control this thyristor (the current in the passport is 100mA, in reality it is 20 mA), it is necessary to reduce the values ​​​​of the resistors R1, R2, R3, we exclude, we increase the capacitance of the capacitor. Capacitance C1 must be increased to 20 microfarads.

The simplest thyristor regulator circuit

Here is another version of the circuit, only simplified, with a minimum of details. 4 diodes are replaced by one VD1. The difference of this scheme is that the adjustment occurs with a positive period of the network. The negative period, passing through the VD1 diode, remains unchanged, the power can be adjusted from 50% to 100%. If you exclude VD1 from the circuit, the power can be adjusted in the range from 0% to 50%.

If you use the KN102A dinistor in the gap from R1 and R2, you will have to replace C1 with a 0.1 uF capacitor. For this circuit, the following thyristor ratings are suitable: KU201L (K), KU202K (N, M, L), KU103V, with a voltage of more than 300 V for them. Diodes are any, the reverse voltage of which is not less than 300 V.

The above schemes are successfully suitable for adjusting incandescent lamps in fixtures. It will not be possible to regulate LED and energy-saving lamps, as they have electronic control circuits. This will cause the lamp to flicker or run at full power, eventually destroying it.

If you want to use regulators to work on a 24.36 V network, you will have to reduce the resistor values ​​\u200b\u200band replace the thyristor with an appropriate one. If the power of the soldering iron is 40 W, the mains voltage is 36 V, it will consume 1.1 A.

Thyristor regulator circuit does not emit interference

This scheme differs from the previous one in the complete absence of the studied radio interference, since the processes take place at the moment when the mains voltage is 0. Starting to create the regulator, I proceeded from the following considerations: the components must have a low price, high reliability, small dimensions, the circuit itself must be simple, easily repeatable, the efficiency should be close to 100%, there should be no interference. The circuit must be upgradeable.

The principle of operation of the scheme is as follows. VD1-VD4 rectify the mains voltage. The resulting DC voltage varies in amplitude equal to half a sinusoid with a frequency of 100 Hz (diagram 1). The current passing through R1 to VD6 - a zener diode, 9V (diagram 2), has a different shape. Through VD5, the pulses charge C1, creating a 9 V voltage for the microcircuits DD1, DD2. R2 is used for protection. It serves to limit the voltage supplied to VD5, VD6 to 22 V and generates a clock pulse for the operation of the circuit. R1 transmits a signal to 5, 6 output of element 2 or a non-logical digital microcircuit DD1.1, which in turn inverts the signal and converts it into a short rectangular pulse (diagram 3). The impulse comes from the 4th output of DD1 and comes to output D No. 8 of the trigger DD2.1, which operates in RS mode. The principle of operation of DD2.1 is the same as DD1.1 (diagram 4). Having examined diagrams No. 2 and 4, we can conclude that there are practically no differences. It turns out that with R1 you can send a signal to pin No. 5 DD2.1. But this is not so, R1 has a lot of interference. You will have to install a filter, which is not advisable. There will be no stable operation without double formation of the scheme.

The control circuit of the regulator is assembled on the basis of the DD2.2 trigger, it works according to the following principle. From output No. 13 of the trigger DD2.1, pulses are sent to the 3rd output of DD2.2, the level of which is rewritten at the output No. 1 of DD2.2, which at this stage are at the D input of the microcircuit (pin 5). The opposite signal level is at pin 2. I propose to consider the principle of operation of DD2.2. Suppose that on pin 2, a logical unit. C2 is charged to the required voltage through R4, R5. When the first pulse appears with a positive drop, 0 is formed at pin 2, C2 will be discharged through VD7. The subsequent drop on pin 3 will set a logical unit on pin 2, C2 will begin to accumulate capacitance through R4, R5. Charging time depends on R5. The larger it is, the longer it will take to charge C2. Until the capacitor C2 accumulates 1/2 capacitance, the 5th output will be 0. The pulse drop at the 3rd input will not affect the change in the logic level at the 2nd output. When the full charge of the capacitor is reached, the process will be repeated. The number of pulses given by the resistor R5 will go to DD2.2. The pulse drop will occur only at those moments when the mains voltage passes through 0. That is why there is no interference on this regulator. From 1 output DD2.2 to DD1.2 pulses are supplied. DD1.2 eliminates the influence of VS1 (thyristor) on DD2.2. R6 is set to limit the control current of VS1. The soldering iron is energized by opening the thyristor. This is due to the fact that the thyristor receives a positive potential from the control electrode VS1. This regulator allows you to adjust the power in the range of 50-99%. Although the resistor R5 is variable, due to the included DD2.2, the soldering iron is adjusted in a stepwise manner. When R5 = 0, 50% of the power is supplied (diagram 5), if rotated to a certain angle, it will be 66% (diagram 6), then 75% (diagram 7). The closer to the calculated power of the soldering iron, the smoother the operation of the regulator. Let's say there is a 40 W soldering iron, its power can be adjusted in the region of 20-40 W.

The design and details of the temperature controller

The details of the regulator are located on a fiberglass printed circuit board. The board is placed in a plastic case from a former adapter with an electrical plug. The plastic handle is put on the axis of the resistor R5. On the body of the regulator there are marks with numbers that allow you to understand which temperature mode is selected.

The soldering iron cord is soldered to the board. The connection of the soldering iron to the regulator can be made detachable in order to be able to connect other objects. The circuit consumes current not exceeding 2mA. This is even less than the consumption of the LED in the backlight of the switch. Special measures to ensure the operation of the device are not required.

At a voltage of 300 V and a current of 0.5 A, microcircuits DD1, DD2 and series 176 or 561 are used; diodes any VD1-VD4. VD5, VD7 - pulse, any; VD6 is a low-power zener diode with a voltage of 9 V. Any capacitors, a resistor too. The power R1 should be 0.5 watts. Additional adjustment of the regulator is not required. If the parts are correct and there were no errors during the connection, it will work immediately.

The scheme was developed long ago, when there were no laser printers and computers. For this reason, the printed circuit board was made according to the old-fashioned method, chart paper was used, the grid spacing of which was 2.5 mm. Further, the drawing was glued with the "Moment" on paper denser, and the paper itself on foil fiberglass. Why holes were drilled, tracks of conductors and pads were drawn manually.

I have a blueprint for the regulator. The photo shows. Initially, a diode bridge with a nominal value of KTs407 (VD1-VD4) was used. They were torn apart a couple of times, I had to replace them with 4 diodes of the KD209 type.

How to reduce noise from thyristor power controllers

To reduce the interference emitted by the thyristor regulator, ferrite filters are used. They are a ferrite ring with a winding. These filters are found in switching power supplies for TVs, computers and other products. Any thyristor regulator can be equipped with a filter that will effectively suppress interference. To do this, it is necessary to pass a network wire through the ferrite ring.

The ferrite filter should be installed near sources that emit interference, directly at the installation site of the thyristor. The filter can be located both outside the housing and inside. The greater the number of turns, the better the filter will suppress interference, but it is also enough to pass the wire going to the outlet through the ring.

The ring can be removed from the interface wires of computer peripherals, printers, monitors, scanners. If you look at the wire that connects the monitor or printer to the system unit, you can see a cylindrical thickening on it. It is in this place that the ferrite filter is located, which serves to protect against high-frequency interference.

We take a knife, cut the insulation and remove the ferrite ring. Surely your friends or you have an old interface cable lying around for a CRT monitor or an inkjet printer.

A power regulator for a soldering iron is a device that allows you to control the soldering process. The quality of this process can be significantly increased if the main parameters are taken under control. A soldering iron is a necessary tool in the household for a person who likes to do everything with his own hands.

The main characteristic of soldering is the maximum temperature at the tip of the soldering iron. The power regulator for the soldering iron ensures that it changes in the desired mode. This allows not only to improve the quality of the metal connection, but also to increase the service life of the device itself.

What is a regulator for?

Soldering of metals is carried out due to the fact that the molten solder fills the space between the workpieces to be joined and partially penetrates into their material. The strength of the connecting seam largely depends on the quality of the melt, i.e. on its heating temperature. If the soldering iron tip has insufficient temperature, then it is necessary to increase the heating time, which can destroy the material of the parts and lead to premature failure of the device itself. Excessive heating of the filler metal leads to the formation of thermal decomposition products, which significantly reduces the quality of the weld.

The temperature of the working area of ​​the soldering tip and the time it takes to set it depend on the power of the heating element. A smooth change in voltage allows you to choose the optimal mode of operation of the heater. Therefore, the main task that the power regulator for the soldering iron must solve is to set the required electrical voltage and maintain it during the soldering process.

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The simplest schemes

The simplest power regulator circuit for a soldering iron is shown in Fig. 1. This scheme has been known for more than 30 years and has shown itself perfectly at home. It allows you to solder parts with power control in the range of 50-100%.

Such an elementary circuit is assembled at the output ends of the variable resistor R1 and is connected by four soldering points. The positive terminal of the capacitor C1, the leg of the resistor R2 and the control electrode of the thyristor VD2 are soldered together. The thyristor case acts as an anode, so it should be isolated. The whole circuit is small and fits into a case from an unnecessary power supply of any device.

A hole with a diameter of 10 mm is drilled on the case wall, in which a variable resistor is fixed with its threaded leg. As a load, you can use any light bulb with a power of 20-40 watts. The cartridge with the light bulb is fixed in the housing, and the top of the light bulb is brought out into the hole so that the operation of the device can be controlled by its glow.

Parts that should be used in the recommended circuit: diode 1N4007 (any similar one for a current of 1 A and a voltage of up to 600 V can be used); thyristor KU101G; electrolytic capacitor with a capacity of 4.7 microfarads for a voltage of 100 V; resistor 27-33 kOhm with power up to 0.5 W; variable resistor SP-1 with a resistance of up to 47 kOhm. The soldering iron power regulator with such a circuit proved to be reliable with EPSN type soldering irons.

A simple but more modern circuit can be based on the replacement of a thyristor and a diode with a triac, and a neon lamp of the MH3 or MH4 type can also be used as a load. The following parts are recommended: triac KU208G; electrolytic capacitor 0.1 uF; variable resistor up to 220 kOhm; two resistors with a resistance of 1 kOhm and 300 Ohm.

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Design improvement

The power regulator, assembled on the basis of the simplest circuit, makes it possible to maintain the soldering mode, but does not guarantee the complete stability of the process. There are a number of fairly simple designs that allow for stable maintenance and regulation of the temperature at the soldering iron tip.

The electrical part of the device can be divided into a power section and a control circuit. The power function is determined by the thyristor VS1. The voltage from the electrical network (220 V) is supplied to the control circuit from the anode of this thyristor.

The operation of the power thyristor is controlled on the basis of transistors VT1 and VT2. The control system is powered by a parametric stabilizer, which includes resistance R5 (to eliminate excess voltage) and a zener diode VD1 (to limit the increase in voltage). Variable resistor R2 provides manual voltage control at the output of the device.

The assembly of the regulator from the installation of the power section of the circuit occurs as follows. The legs of the diode VD2 are soldered to the conclusions of the thyristor. The R6 resistance legs are connected to the control electrode and the thyristor cathode, and one R5 resistance leg is connected to the thyristor anode, the second leg is connected to the VD1 zener diode cathode. The control electrode is connected to the control unit by connecting to the emitter of the transistor VT1.

The basis of the control unit is silicon transistors KT315 and KT361. With their help, the magnitude of the voltage created on the control electrode of the thyristor is set. The thyristor passes current only if an unlocking voltage is applied to its control electrode, and its value determines the strength of the transmitted current.

The entire circuit of the regulator has a small-sized design and can easily be placed in the case of a surface-mounted socket. A plastic housing should be selected to simplify drilling holes. It is advisable to assemble the power part and the control unit on different panels, and then connect them with three wires. The best option is to assemble panels on textolite coated with foil, but in practice all connections can be made with thin wires and panels can be assembled on any insulating plate (even on thick cardboard).

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Do-it-yourself power regulator assembly

The device is assembled inside the socket housing. The output ends are connected to the socket contacts, which will make it possible to connect the soldering iron by simply inserting its plug into the socket sockets. In the case, first, a variable resistor should be fixed, and its threaded part should be brought out through the drilled hole. Then a thyristor with a mounted power unit should be placed in the housing. Finally, a control panel is installed in any free space. From below the socket is closed by a cover. A cord with a plug is connected to the input of the power unit, which is led out of the socket housing for connection to the electrical network.

Before connecting the soldering iron, the power regulator should be checked. To do this, a voltmeter or multimeter is connected to the outputs of the device (to the socket). A voltage of 220 V is applied to the input of the device. By smoothly rotating the knob of the variable resistor, observe the change in the reading of the device. If the voltage at the output of the regulator increases smoothly, then the device is assembled correctly. The practice of using the device shows that the optimal value of the output voltage is 150 V. This value should be fixed with a red mark indicating the position of the variable resistor knob. It is advisable to note several voltage values.

A soldering iron is a tool that a home craftsman cannot do without, but the device is not always satisfied. The fact is that a conventional soldering iron, which does not have a thermostat and, as a result, heats up to a certain temperature, has a number of disadvantages.

Soldering iron diagram.

If during short work it is quite possible to do without a temperature controller, then for an ordinary soldering iron, which has been connected to the network for a long time, its shortcomings are fully manifested:

• solder rolls off an overheated tip, as a result of which the soldering is fragile;
• scale forms on the sting, which often has to be cleaned;
• the working surface is covered with craters, and they must be removed with a file;
• it is uneconomical - in the intervals between soldering sessions, sometimes quite long, it continues to consume rated power from the network.

The thermostat for the soldering iron allows you to optimize its operation:

Figure 1. Scheme of the simplest thermostat.

• the soldering iron does not overheat;
• it becomes possible to choose the temperature value of the soldering iron, which is optimal for a particular job;
• during breaks, it is enough to reduce the heating of the tip using the temperature controller, and then quickly restore the required degree of heating at the right time.

Of course, LATR can be used as a thermostat for a 220 V soldering iron, and a KEF-8 power supply for a 42 V soldering iron, but not everyone has them. Another way out is to use an industrial dimmer as a temperature controller, but they are not always commercially available.

Do-it-yourself temperature regulator for a soldering iron

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The simplest thermostat

This device consists of only two parts (Fig. 1):

1. Pushbutton switch SA with NC contacts and latching.
2. Semiconductor diode VD, designed for a forward current of about 0.2 A and a reverse voltage of at least 300 V.

Figure 2. Scheme of a thermostat operating on capacitors.

This temperature controller works as follows: in the initial state, the contacts of the switch SA are closed and the current flows through the heating element of the soldering iron during both positive and negative half-cycles (Fig. 1a). When the SA button is pressed, its contacts open, but the semiconductor diode VD passes current only during positive half-cycles (Fig. 1b). As a result, the power consumed by the heater is halved.

In the first mode, the soldering iron warms up quickly, in the second mode, its temperature decreases slightly, overheating does not occur. As a result, you can solder in fairly comfortable conditions. The switch, together with the diode, is connected to the break in the supply wire.

Sometimes the SA switch is mounted on a stand and is triggered when the soldering iron is placed on it. During the breaks between soldering, the switch contacts are open, the heater power is reduced. When the soldering iron is lifted, the power consumption increases and it quickly heats up to operating temperature.

Capacitors can be used as a ballast resistance, with which you can reduce the power consumed by the heater. The smaller their capacitance, the greater the resistance to the flow of alternating current. A diagram of a simple thermostat operating on this principle is shown in fig. 2. It is designed to connect a 40W soldering iron.

When all switches are open, there is no current in the circuit. By combining the position of the switches, three degrees of heating can be obtained:

Figure 3. Schemes of triac thermostats.

1. The lowest degree of heating corresponds to the closing of the contacts of the switch SA1. In this case, capacitor C1 is connected in series with the heater. Its resistance is quite high, so the voltage drop across the heater is about 150 V.
2. The average degree of heating corresponds to the closed contacts of switches SA1 and SA2. Capacitors C1 and C2 are connected in parallel, the total capacitance is doubled. The voltage drop across the heater increases to 200 V.
3. When the SA3 switch is closed, regardless of the state of SA1 and SA2, the full mains voltage is applied to the heater.

Capacitors C1 and C2 are non-polar, designed for a voltage of at least 400 V. To achieve the required capacity, several capacitors can be connected in parallel. Through resistors R1 and R2, the capacitors are discharged after the regulator is disconnected from the network.

There is another version of a simple regulator, which is not inferior to electronic ones in terms of reliability and quality of work. To do this, a variable wire resistor SP5-30 or some other one with a suitable power is switched on in series with the heater. For example, for a 40-watt soldering iron, a resistor rated for 25 W and having a resistance of about 1 kOhm is suitable.

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Thyristor and triac thermostat

The operation of the circuit shown in fig. 3a, the operation of the previously analyzed circuit in Fig. 1. Semiconductor diode VD1 passes negative half-cycles, and during positive half-cycles, the current passes through the thyristor VS1. The proportion of the positive half-cycle, during which the thyristor VS1 is open, ultimately depends on the position of the variable resistor R1 slider, which regulates the current of the control electrode and, consequently, the firing angle.

Figure 4. Scheme of a triac thermostat.

In one extreme position, the thyristor is open during the entire positive half-cycle, in the second it is completely closed. Accordingly, the power dissipated on the heater varies from 100% to 50%. If you turn off the VD1 diode, then the power will change from 50% to 0.

In the diagram shown in fig. 3b, a thyristor with an adjustable firing angle VS1 is included in the diagonal of the diode bridge VD1-VD4. As a result, the regulation of the voltage at which the thyristor is unlocked occurs both during the positive and during the negative half-cycle. The power dissipated on the heater changes when the variable resistor R1 slider is turned from 100% to 0. You can do without a diode bridge if you use a triac instead of a thyristor as a control element (Fig. 4a).

For all its attractiveness, a thermostat with a thyristor or triac as a control element has the following disadvantages:

• with an abrupt increase in current in the load, strong impulse noise occurs, which then penetrates into the lighting network and the air;
• distortion of the mains voltage shape due to the introduction of non-linear distortions into the network;
• power factor reduction (cos ϕ) due to the introduction of a reactive component.

To minimize impulse noise and non-linear distortion, it is desirable to install network filters. The simplest solution is a ferrite filter, which is a few turns of wire wound around a ferrite ring. Such filters are used in most switching power supplies for electronic devices.

A ferrite ring can be taken from the wires connecting the computer system unit to peripheral devices (for example, to a monitor). Usually they have a cylindrical thickening, inside of which there is a ferrite filter. The filter device is shown in fig. 4b. The more turns, the higher the quality of the filter. The ferrite filter should be placed as close as possible to the source of interference - a thyristor or triac.

In devices with a smooth change in power, the regulator slider should be calibrated and its position should be marked with a marker. When setting up and installing, you must disconnect the device from the network.

The schemes of all the above devices are quite simple and they can be repeated by a person with minimal skills in assembling electronic devices.