How to make a power regulator for a soldering iron? Power regulator for soldering iron by hand: diagrams and instructions

Devices for adjusting the voltage level applied to the heating element are often used by radio amateurs to prevent premature destruction of the soldering tip and improve the quality of the soldering. The most common power regulator circuits for a soldering iron contain two-position contact switches and trinistor devices installed in the stand. These and other devices provide the ability to select the required voltage level. Today self-made and factory installations are applied.

A simple power regulator for a soldering iron

If you need to get 40 watts from a soldering iron for 100 watts, you can apply the circuit to triac BT 138-600. The principle of operation is to trim the sinusoid. The cutoff level and the heating temperature can be adjusted using a resistor R1. Neon light acts as an indicator. You do not have to put it. A triac BT 138-600 is installed on the radiator.

Housing

The entire circuit must necessarily be placed in a closed dielectric housing. The desire to make the device miniature should not affect the safety when using it. Remember that the device works from a 220 V voltage source.

Trinistor power regulator for soldering iron

As an example, you can consider a device designed for a load of several watts to a hundred. The range of regulation of the rated power of such a device varies from 50% to 97%. The device uses a KU103B trinister with a holding current of not more than one milliampere.

Via the diode VD1, negative half-waves of voltage pass unhindered, providing approximately half of the total power of the soldering iron. It can be controlled by the trinistor VS1 during each positive half-cycle. The device is turned on and off diode VD1. The transistor is controlled by the phase-impulse principle. The generator generates pulses arriving at a control electrode consisting of a time-determining circuit R5R6C1 and a unijunction transistor.

The position of the handle of the resistor R5 determines the time from the positive half-cycle. The power regulator circuit requires temperature stability and increased noise immunity. To do this, shunt the control transition resistor R1.

Chain R2R3R4VT3

The generator is powered by pulses of voltage up to 7V and a duration of 10 ms formed by the R2R3R4VT3 circuit. The transition of the transistor VT3 is a stabilizing element. It turns on in the opposite direction. The power dissipated by the resistor circuit R2-R4 will be reduced.

The power regulator circuit includes a capacitor C1KM5, resistors - MLT and R5 - SP-0.4. A transistor can be used either.

Board and housing for the device

For the assembly of this device, a foil-plated fiberglass board with a diameter of 36 mm and a thickness of 1 mm is suitable. For the case, you can use any items, such as plastic boxes or cases of material with good insulation. You will need a base for the plug elements. For this, two nuts M 2,5 can be soldered to the foil in such a way that the pins press the board against the body during assembly.

Disadvantages of trinistors KU202

If the power of the soldering iron is small, regulation is possible only in the narrow half-cycle. In the one where the holding voltage of the trinistor is at least slightly lower than the load current. Temperature stability can not be achieved by using such a power regulator for a soldering iron.

Increasing regulator

Most of the devices for temperature stabilization work only to reduce power. The voltage can be adjusted from 50-100% or from 0-100%. The power of the soldering iron may not be sufficient in the event of a power supply below 220 V, or, for example, if necessary, to drain out a large old board.

The effective voltage is smoothed by an electrolytic capacitor, increases by 1.41 times and feeds the soldering iron. The constant power rectified on the capacitor will reach 310 V at 220 V supply. The optimum heating temperature can be obtained even at 170 V.

Powerful soldering irons do not need step-up regulators.

Necessary parts for the circuit

To assemble a convenient power regulator for a soldering iron with your own hands, you can use the surface mounted method near the outlet. This requires small-sized components. The power of one resistor should be not less than 2 W, and the rest - 0,125 W.

Description of the circuit of the power regulator

The electrolytic capacitor C1 with the bridge VD1 is equipped with an input rectifier. Its operating voltage should not be less than 400 V. The field output transistor IRF840 houses the output of the regulator. With this device, you can use a soldering iron up to 65 W without a radiator. They can be heated above the desired temperature even with reduced power.

The key transistor located on the DD1 chip is controlled by a PWM oscillator, whose frequency is set by the capacitor C2. The parametric stabilizer is mounted on instruments C3, R5 and VD4. It feeds the DD1 chip.

To protect the output transistor from self-induction, a diode VD5 is installed. It can be omitted if the soldering power regulator is not to be used with other electrical appliances.

The possibility of replacing parts in regulators

The DD1 chip can be replaced with K561LA7. The rectifier bridge is made of diodes designed for a minimum current of 2A. The IRF740 can be used as an output transistor. The circuit does not need an overlay, if all the parts are working and there were no errors in its assembly.

Other possible options for voltage dissipation devices

Simple schemes of power regulators for a soldering iron, working on triacs KU208G, are assembled. All their cunning in the condenser and neon light, which, changing its brightness, can serve as an indicator of power. Possible adjustment is from 0% to 100%.

In the absence of a triac or a bulb, a thyristor KU202H can be used. It is a very common device with many analogues. With its use it is possible to assemble a circuit operating in the range from 50% to 99% of the power.

A ferrite ring from a computer cord can be used to make a loop to extinguish possible interference from triac or thyristor switching.

Arrow indicator

A dial indicator can be integrated into the soldering iron power regulator for greater ease of use. It is not difficult to do this. Unused old audio equipment can help with finding such items. Appliances are easy to find in local markets in any city. Well, if one of these is at home without work.

For example, let's consider the possibility of integrating the indicator M68501 with an arrow and digital marks into the power regulator for the soldering iron, which was installed in old Soviet tape recorders. The peculiarity of tuning is the selection of resistor R4. For certain it is necessary to select the device R3 additionally, if other indicator will be used. It is necessary to observe the appropriate balance of resistors when the power of the soldering iron decreases. The fact is that the indicator's arrow can display a power reduction of 10-20% when the actual consumption of soldering iron is 50%, that is, half less.

Conclusion

The power regulator for the soldering iron can be assembled, guided by the set of instructions and articles with the given examples of possible various schemes. From the good solders, fluxes and the temperature of the heating element, the quality of the adhesion largely depends. Complex devices for stabilization or elementary integration of diodes can be used to assemble devices needed to regulate the incoming voltage.

Such devices are widely used to reduce, as well as increase the power supplied to the heating element of the soldering iron in the range from 0% to 141%. It is very convenient. There is a real opportunity to work at a voltage below 220 V. In the modern market, high-quality devices are available, equipped with special regulators. Factory devices only work to reduce power. Increasing regulator will have to be collected independently.