DIY battery-powered pulse soldering iron. DIY cordless soldering iron. How should the working surface of a soldering iron tip be processed?
When you need to solder in a limited space for work, and there is no suitable power source nearby, a cordless soldering iron will come in handy. There are a great variety of such instruments.
And if in most cases it is more convenient, for example, on the roof of a building to repair an antenna, then when repairing electronic devices, when low temperatures and caution when soldering are required, it is more convenient to use a soldering iron with a battery or batteries.
Despite its compact size, this soldering iron can heat the tip up to 450 ℃. The charge of two batteries is enough for several rations.
Due to the fact that the presence of batteries in the design makes the tool quite heavy, and the time of use is limited, it is not practical to use it in the workshop for everyday installation work. But when repairing radio equipment, when the use of extension cords is impossible, this will be a completely justified decision.
Currently, the choice of battery-powered soldering irons is huge, but the price of models worthy of at least some attention, presented in numerous online stores, is quite high.
If you plan to use an electric soldering iron not very often, it is irrational to pay 1500-2000 rubles for it. It is quite possible to make such a tool yourself.
Of course, such a soldering iron will not be so ergonomic, but it will be able to perform its functions, and the costs of its manufacture will pay off instantly.
Necessary materials for production
So, to make your own mini soldering iron powered by batteries, you need to prepare the following materials:
- a piece of copper wire with a diameter of 4-5 mm and a length of 50 mm;
- a piece of copper foil 30x50 mm;
- nichrome thread with a diameter of 0.2 mm and a length of about 400 mm;
- insulating tape;
- metal tube for electric heater;
- silicate glue or liquid glass;
- talc powder;
- 2 batteries with a voltage of 1.5 V (AA batteries).
You should begin work by making a tip, since the structure of the future soldering iron will be built on it. Using a copper wire for the tip, you need to sharpen its working end in the form flat screwdriver at an angle of 45°.
The width of the tip is determined by the nature of the future work and can vary from 2 to 5 mm. With particularly precise soldering, the tip can be sharpened, giving it almost the shape of an awl.
Insulation and heater
Next, you need to cover the back of the tip, on which the heating element will be located, with a mixture of silicate glue and talc. It is better to prepare it in advance by mixing the ingredients until the consistency of sour cream. The mixture will act as an insulating layer.
After the mixture has dried, it is necessary to wrap a copper foil tube over it on the tip so that the length of the tube is no more than 30 mm, and the tip protrudes from the tube by no more than 10 mm.
Another layer of insulating mass is applied on top and dried at room temperature. It is not recommended to dry it over a fire, as the glue may crack. You can speed up drying by carefully using a hair dryer.
On top of the dried layer of insulating mass you need to wrap nichrome wire, leaving its two ends free. The length of one should be 30 mm, the other - 60.
To make working with a soldering iron more comfortable, it is advisable to experiment with the length of the thread, connecting batteries to it and shortening the wire to the required length, achieving the required temperature.
The finished winding must be covered with an insulating mixture and wait until it hardens. The long winding lead is laid on top of the insulating layer, brought out next to the short one, and the entire winding is once again covered with a layer of insulation.
To connect heating element battery-powered soldering iron to the ends nichrome thread two need to be connected copper wires and insulate the connections with insulating tape.
Housing and switch
The body of a mini soldering iron can be made from a suitable plastic tube with internal diameter 18-20 mm. This is enough to place the batteries and the wires going to them inside. Contact plates can be made from strips of tin.
For the switch, two blade contacts are output to the body, which will close if you hold the soldering iron in your hand. It is advisable to insulate the contacts with the exception of surfaces that will come into contact when switched on. The switch must be connected to the break of one of the supply wires.
Such a simple battery-powered soldering iron can provide a power of 25-40 W. It is quite enough to melt most tin-lead solders used for soldering semiconductor devices, microcircuits, and SMD components.
This review examines a portable soldering iron that runs on batteries and is cordless. The device is fully functional, has its own niche, and can be used in practice. Next is a test.
A few words about “niche”. The device is intended for TROUBLESHOOTING AND MINOR REPAIRS. Not for installation (although you can also use it if there is nothing else). Why is this so - the soldering iron is much heavier than its wired brother and is inferior to it in power supply - it is simply inconvenient to swing it for a long time. On the other hand, it does not intersect in any way with gas soldering irons- those are designed for “climb onto the roof, solder the antenna”; they are not suitable for picking electronics. The idea of such a soldering iron came to me while repairing a TV - Google told me about the treatment - 4 SMD transistor, one of which is rotten and needs to be replaced. Naturally, it turned out to be the last, and I had to do the following routine (since during the repair the box was just lying on the floor - I do not live in a workshop): Disconnect the TV from the network - disconnect the interfering cables - turn on the soldering iron and wait for it to heat up - replace the transistor - turn off soldering iron and take it away so as not to burn the carpet - the cables are in place - the box is in the network. And so 4 times :) If the soldering iron were small and cordless, it would simply lie on the TV chassis, and it would be its tail that would get in the way.
And so, I had to tighten it up 
Set: a protective cap-cover for the tip, a poor but working stand and a spiral of low-melting solder. You put on the cover - the switch-on fuse moves, and the soldering iron cannot be put into operation. 
I’m testing it: I’ve long wanted to replace the red LED in one of the mice with a blue one, the very job for this soldering iron. I swap LEDs along with ballast resistors 
Fine. It's quite possible to work. This is despite the fact that I use refractory solder 
it (according to the scale of a soldering iron with a thermostat) should be heated to 350 degrees, so that it does not have to be spread like plasticine. The soldering iron copes with non-massive terminals.
On the catcher and the beast - I was visiting, the light went out, I confiscated it, opened it - and it was already being repaired :) They changed the ballast. Soldered the flask like this 
As you can see, the near end has fallen off, and HOW it was soldered can be seen on the far end. Kick. I'm correcting 
Warming up the soldering iron tip to operating temperature happens in about twenty seconds. Cooling to “can be removed” temperature - about a minute. For the long-playability test, I took an ancient power supply unit, which I should have thrown away a long time ago, but I was sorry for the parts. And everything there is massive. Well, I sat down and slowly soldered them. Of course, with a hundred-watt soldering iron and the appropriate tip, I would have split it apart in an instant, but, nevertheless, things went on 
In general, with enelupes inside, really, about half an hour real work. (On the blister it says - 1 hour) During repairs, the entire TV can be plowed. Even Soviet. 
It looks like this in the hand 
Please note that in general the case hints that it should be held this way, it’s more convenient 
but then there is nothing to press the button with. The button is a blue, easy-to-press bubble located inside the orange safety slide. Until you move it, you can’t press the button. The activation of heating is indicated by the lighting of the red LED. Even a child can work - it’s easy 
I was unable to neatly solder thick wires (network cable, stranded) with this solder. That is, everything is holding together, everything is strong, but there are lumps and snot due to lack of heating. IN emergency It will do, but then it will have to be redone.
Summary - with soldering of elements on printed circuit boards- it copes with a bang (the fallen wires from the diode on the star were also soldered normally, although it is more difficult than with a network solder), something large - there are already nuances.
The sting looks like this, it is easily removable 
Personally, on the farm, it “suited me.” I'm thinking of trying to convert it to lithium, or what?
Do you think the gadget is free? Well, no - a lot of points have accumulated, it’s time to shake them up a little...
Thank you for attention!
On the Aka Kasyan channel, one of the options for making a cordless soldering iron is discussed. A similar soldering iron in online stores costs from 15 to 50 dollars, but we can’t afford it, so it will be cheaper to make it yourself.
Watch from 1:50 minutes
A sting with a heater, how to make it, is shown in the video at the end of the publication.
Li-ion battery standard 18650, the larger the capacity, the better. Charging board for one can of lithium battery with protection based on the TP4056 chip. MT3608 boost DC-DC converter module. The case is from a cheap charging 18650 battery, in which the filling of the soldering iron will be assembled. A small switch with a lock, as long as the dimensions are compact. Current is about 3 A and higher.
Where to buy radio components, etc.
You can buy a cordless soldering iron in this Chinese store. You will find the DC-DC converter there by typing in the search: MT3608 2A Max DC-DC Step. Buy a charge board by searching for: Li-Ion Professional 5V Micro USB 1A 18650.
Here is a diagram of a soldering iron. Why everything is so complicated, you will understand later.
Battery soldering iron circuit
Making a soldering iron body
At the very beginning we prepare the body. Lightly processed, removed all unnecessary. This option is convenient because the battery can be changed or replaced if necessary. The case may be different, as long as the battery fits. A pair of 20 milliliter medical syringes is perfect.
The working part of the soldering iron had to be somehow adapted. Fixed it on a terminal made of ebonite. If you work with a soldering iron continuously for ten minutes, the ebonite begins to smell slightly. But the advantage of using this button is that it has a brass bushing with a thread and no additional gadgets are needed to fix the working part.
The body is plastic, and to prevent the ebonite retainer from melting it, I decided to trim the front part of the body and replace it with an implant made of fiberglass. Then I glued all these parts together with Chinese epoxy resin.
DC-DC converter
Why is it needed? The fact is that the heater is designed for an operating voltage of about 9 volts. You can do without a converter. if you use 2 batteries connected in series. But in this case the costs increase, dimensions and the weight of the soldering iron. In addition, it will become problematic to charge the soldering iron from a regular USB connector.
Why didn’t the master make a heater tailored for one can of lithium? ion battery, already explained in the first video.
Let's return to the converter. Quite a popular thing. The maximum output voltage can be about 28 volts at a current of up to 2 A. But real tests have shown that it begins to boil already at inflows of 1 A. If the output rectifier diode and the microcircuit heat up ungodly, but at some point the temperature stops rising, then with the inductor In general, things are bad. After a while it starts to stink. Therefore, I decided to replace it. I had a non-working Chinese 3 A voltage stabilizer module at hand. I simply replaced one inductor with another.
Power inverter
Next, we connect the inverter to a lithium battery, or even better, to a laboratory power source. We apply a voltage of 3.8-4 volts during operation. By rotating the line resistor we achieve 9 volts of output voltage.
I did not change anything on the lithium battery charging board. The charging current is around 1 A, which is quite satisfactory. The only thing I did was replace 2 LED indicators. I used a two-color LED, which brought it to a prominent place. By the way, this board is equipped with protection that will turn off the battery when the latter is discharged below a critical level.
If needed for a long time If you work in the field, you can take a couple of charged batteries with you and quickly replace them if necessary.
It is impossible to mix up the connection if you follow the picture above.
In addition to the charge indicator, I added an LED that lights up when the soldering iron is turned on.
Soldering iron testing
And now that the device is assembled, you can test it. The tip can heat up to a temperature of 350 degrees, but the best thing is that the inverter allows you to regulate the output voltage, and therefore the heating temperature of the tip. So, if you wish, you can output a variable resistor to comfortable spot and get a cordless soldering iron with the ability to adjust the temperature. This is one of the advantages of using an inverter.
Of the minuses. We lose 5-10 percent of power for conversion. This is a minus, given that the instrument is portable and every milliwatt in this case is expensive.
The soldering iron can be used as a USB charger for the 18650 standard - also a small bonus.
Homemade cordless soldering iron How to make a soldering iron tip
