How to make a power controller soldering iron do it yourself

In order for the soldering to be of high quality, you need to assemble a power controller for the soldering iron with your own hands. Below are the devices that are assembled on thyristors. In some of them, the power of the soldering iron is controlled without galvanic isolation from the electrical network, therefore all current-carrying parts must be carefully insulated.

Diagram of a simple power control for a soldering iron

Diagram of a simple power control for a soldering iron.

Simple thyristor controller

This is the easiest option. It uses the minimum number of parts. Instead of the usual diode bridge, only one diode is used. The temperature is regulated only during the positive half-wave of the current, and during the negative period the voltage goes through the diode without any changes. Therefore, adjusting the power of the soldering iron with your own hands in this case can be carried out in the range from 50 to 100%. If you remove the diode, then it will shift to the range of 0-49%. If a dynistor (KH102A) is inserted into the resistance circuit break, the electrolyte can be exchanged for a conventional capacitor with a capacity of 0.1 microfarad.

To make such a power regulator, it is necessary to use thyristors of the type KU103V, KU201L, KU202M, which operate with a direct voltage of more than 350 V. You can use any of the opposite potential difference of at least 400 volts for the reverse voltage.

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The classic version of the device on the thyristor

Thyristor controller circuit

Thyristor controller circuit.

It gives radio interference to the network and requires the installation of a filter. But it can be successfully used to change the brightness of incandescent lamps or change the temperature of heating elements with a power of 20 to 40 watts.

Such a device works according to the following principle:

  • the device is powered through the device, the temperature or brightness of which must be changed;
  • then the current passes to the diode bridge;
  • it converts alternating current into direct current;
  • through a variable resistor and a filter of two resistances and a capacitor falls on the control output of the thyristor, which opens and passes the maximum current value through a light bulb or a soldering iron;
  • if you turn the knob of the variable resistor, then this process will take place with a delay, which depends on the time of discharge of the capacitor;
  • the level of temperature to which the soldering iron tip will heat up depends on this.
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Soldering iron power controller without radio interference

The difference of this option from the previous one is in the absence of interference in the electrical network. It works in the period when the supply voltage passes through the zero point. It is easy to make such a soldering iron regulator with your own hands, and its efficiency reaches 98%. Well amenable to subsequent modernization.

Soldering iron design

Soldering iron design.

The device works as follows: the network voltage is smoothed by a diode bridge, and the constant component has the form of a sinusoid, which pulses with a frequency of 100 Hz.

After passing through the resistance and the Zener diode, the current has a maximum voltage amplitude of 8.9 V. Its shape changes and becomes pulsed, and it recharges the capacitor.

The microcircuits receive the necessary power, and the resistances are needed to reduce the amplitude of the voltage of about 20–21 V and provide a clock signal for the LSI and separate logic cells 2OR-NOT, which all convert to rectangular pulses. On the other outputs of the microcircuits, the inverting and formation of the pulse clock takes place so that the thyristor cannot influence the logic. When a positive signal is passed to the control output of the thyristor, it opens and it can be soldered.

This power regulator of the soldering iron has a range of 49-98%, which allows you to adjust the tool in the range from 21 to 39 watts.

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Internal installation of the device and its other parts

All parts from which the regulator is assembled are located on a printed circuit board, which is made of fiberglass. This device does not contain galvanic isolation and is directly connected to the mains, so it is better to install the device in a box of any insulating material, such as plastic. It should be no more than an adapter. You will also need an electrical cord with a plug.

The handle of any insulating material, for example, PCB or plastic, should be worn on the axis of the variable resistor. Around her on the case of the power regulator of the soldering iron cause risks with the corresponding figures that will show the degree of heating of the tip.

The cord connecting the regulator with a soldering iron, soldered directly to the board. You can install connectors on the case instead, and then you can connect several soldering irons. The current consumed by the device described above is quite small. It is equal to 2 mA, and this is less than the LED in the backlit switch takes. Therefore, you can not apply any effort to ensure the temperature.

After assembly, the device does not require adjustment. If there are no errors in the installation and all the details are intact, then the power regulator should work immediately after the plug is turned on.

If the above-described device seems to be difficult to manufacture, it can be made simpler, but to reduce radio interference, additional filters will have to be mounted. They are made of ferrite rings, on which are wound coils of copper wire.

You can use similar items taken from computer power supplies, printers, televisions and other similar equipment.

The filter is installed at the entrance to the regulator, between the device and the power cord.

It should be installed as close as possible to the thyristor, which is the source of radio interference. The filter can also be placed in or on the inside of the enclosure. The more coils wound on it, the more secure the network is from interference. In the simplest case, you can wind on the ring 2-3 wires of the power cord. You can remove ferrite cores from computers, useless printers, old monitors, or scanners. The PC system unit is connected to them with a cord that has a thickening. In it and mounted ferrite filter.

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Details from which the power regulator is assembled

  1. Series 176 or lower-power chips, such as 561.
  2. Bridge diodes of any type (for example, KD209), with a breakdown voltage of at least 400 V at a current of 0.6 A, and those near the logic elements are any pulsed that withstand up to 9 volts.
  3. The Zener diode can be taken of any type, for a stabilization voltage of 8.9-11 V.
  4. Capacitors can be used any.
  5. Resistance should be 0.5-1 watts.

Nominal details.

Based on the described designs, you can assemble a dimmer. It will be good to change the brightness of conventional incandescent bulbs from zero to maximum. It is also possible to apply them to heaters in an aquarium. It is also possible to adjust the alternating voltage in networks with ratings of 24 or 36 V, for example, at workplaces in the workshop of a radio factory. In this case, it is necessary to change the numbers on the resistances by an order of magnitude and use another thyristor device, since, for example, at 36 V the current on a soldering iron or a 38 W heater will reach 1.2 A.

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