Once, while walking through the expanses of Aliexpress, I saw a USB soldering iron on sale. I was surprised. Can a normal soldering iron be powered from USB, where the supply voltage is only 5 Volts? But out of curiosity, I still ordered this copy.
Convenient small soldering iron. Fits perfectly in the hand.
You can look at this soldering iron for yourself this link.
Weighs only about 20 grams
The kit includes a 1.5 meter cord with the following connectors at the ends:
as well as a stand for the soldering iron itself
All assembled it looks like this:
USB power supply: take a power supply that produces a current of at least 2 Amps
Soldering iron energy consumption
In order to find out the power consumption of USB consumers, I have this device
I connect the soldering iron to the block through this device
When you turn on the soldering iron, the red LED on it lights up
So, the voltage supplied to the soldering iron is 4.9 Volts
The current consumed by the soldering iron is 1.44 Amperes
Therefore, the power consumption of the soldering iron is: P = IU = 1.44 x 4.9 = 7 Watt with kopecks.
Checking the soldering iron in operation
This soldering iron heats up very quickly due to its small dimensions. The fireproof thin nickel tip will serve you faithfully for a long time. As a last resort, you can buy it on Aliexpress without any problems.
The solder melts once and twice!
And of course, the best feature: automatic shutdown. If you do not touch the soldering iron, it will automatically turn off after 25 seconds! As soon as we want to pick it up, the contactless sensor on it is triggered, and the soldering iron is ready for battle again. Well, honestly, I didn’t expect this from the Chinese.
Conclusion
Well, what else can you say about this soldering iron? It is unlikely that you will be able to solder large parts, but various small things will work just fine. Is it possible to power it from Computer USB or laptop? Mmm... Well, I plugged it into a laptop and it worked fine for me, but I strongly do not recommend doing this! Still, it is better NOT to use the USB ports of your computers to power the soldering iron. As you remember, they are intended for other purposes. If you buy a Power Bank in addition to it, you can solder even in an open field. This is much more convenient than using a bulky and smelly gas soldering iron.
Such a soldering iron will be an excellent purchase for young radio amateurs, since many of them forget to unplug the soldering iron from the outlet, and also in such a USB soldering iron there is no voltage of 220 Volts, which in itself is considered unsafe. So, parents, if you still want to buy for your child good soldering iron, take a closer look at this USB soldering iron. I've been using it periodically for a month now. He showed himself with the best side. Reviews on the Internet about it are also good. Further use will show what this soldering iron is capable of in terms of longevity;-)
A USB soldering iron, familiar to many, is a device for soldering parts, powered by a specialized computer connector.
In addition to the device itself, the delivery set of this device includes a connecting cord one and a half meters long, as well as a small metal stand and several coils of solder rolled into a spiral.
Externally, the USB soldering iron looks like a wireless product equipped with a special connecting cord. The mini soldering iron is also equipped with a special plastic plug that protects its working tip from accidental damage.
As for the one and a half meter connecting cord, one of its ends is made in the form of a classic USB connector, and the second ends with a regular 3.5 millimeter “Jack” feeder.
The manufacturer that organizes the supply of portable USB soldering irons to the domestic market guarantees the following performance characteristics:
- small dimensions and compactness of the device, which greatly facilitates its handling during the soldering process;
high speed of heating the tip (this takes no more than 15 seconds); - fairly rapid cooling of the working tip (usually 25-30 seconds is enough);
- the power consumption of the device does not exceed 8 watts;
- operating power - from a USB connector with a voltage of 5 Volts;
- the presence of a timer that automatically turns off the mobile device after a programmed period of time.
The soldering iron is turned on when you touch its body with your hand (due to the built-in touch sensor).
Finalization
The main advantages of a USB soldering iron (almost instantaneous heating and the presence of an automatic switching mode) in practice turn into disadvantages, the elimination of which requires its modification.
These disadvantages are expressed as follows:
- severe overheating of the tip in the absence of forced cooling;
- premature switching on of the soldering iron, associated with increased sensitivity of the sensor and also leading to overheating;
- a delay in turning off the device, in some samples reaching 45 seconds, as a result of which the same overheating and failure of the device are observed.
These deviations from the norm are found in most reviews of work heating devices of this class and require changes to their electronic circuit.
Based on all of the above, independent modification of a soldering USB device should be reduced to the following.
Firstly, it is necessary to slightly reduce the sensitivity of the built-in sensor, which should respond clearly when touched by hand. To do this, it is enough to solder an additional capacitor with a capacity of about 2.2 nF between the touch contact and the ground power bus.
Secondly, the delay time for turning off the soldering iron after returning to the stand should be reduced, which will eliminate dangerous overheating. For this purpose, it is necessary to reduce the value of the timing resistor connected to the NE555 timer from 200 to 47 kOhm.
Upon completion of all these modifications, working with a USB soldering iron is greatly simplified, since after reducing the sensitivity, you can control the heating of the device directly during operation. These improvements also extend the life of the heating element.
Positive reviews
Among the user reviews about the operation of the USB soldering iron, its advantages are especially noted, such as its almost pocket format, which allows you to store it directly in your work clothes.
The advantages of this device also include high speed tip heating and automatic disconnection from the power line. The soldering iron fits comfortably in your hand and allows you to melt solder in any spatial position.
Individual users are not limited to just technical advantages USB soldering iron and also note beautiful design and ease of use of the soldering device.
Particular attention is drawn to the fact that the USB-powered device is quite mobile and can be used to repair the on-board power supply systems of modern cars equipped with the appropriate connectors.
Flaws
Some users attribute the disadvantages of a mini soldering iron to the insufficient power developed by the heating element.
Sometimes it is not enough to warm up the soldering zone and, especially, when working with large and thermally resistant metal products.
An analysis of user reviews showed that many radio amateurs prefer to use a USB soldering iron to work with small details and most often they connect it not to a computer, but to a separate adapter or unit.
And this is explained, first of all, by the fact that it is advisable to use the corresponding computer connector according to its direct purpose, without loading with a sufficiently powerful consumer.
This device is ideal for primary education young radio amateurs, since its circuit does not contain life-threatening high voltage.
In addition, after soldering, children often forget to turn off the normal electric soldering iron from the network, which is in in this case is done automatically.
To summarize all that has been said, we note that in general, the soldering device with a USB connector fully complies with the characteristics stated in its technical description.
However, the greatest return from such a soldering iron can be achieved only after minor modifications to it. electrical diagram, the procedure for which was described earlier.
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 lithium battery with protection based on the TP4056 chip. MT3608 boost DC-DC converter module. A case 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.
Buy battery soldering iron you can 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 case is plastic and so that the ebonite retainer does not melt it, I decided to trim the front part of the case 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 to work in field conditions, then 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 bring the variable resistor to a convenient place 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.
Soldering iron can be used as USB Charger for the 18650 standard this is also a small bonus.
Homemade cordless soldering iron How to make a soldering iron tip
The main advantage of this mini soldering iron is that it is powered by battery voltage 3.7 V. It is not connected to the network and you can easily take it with you. Of course, its power is not great, but it is quite enough to solder wires or solder some fallen radio element.
So, what do you need to make a mini soldering iron?
- Single-core wire with a core diameter of 2 mm.
- A piece of a telescopic antenna.
- Nichrome, wire 0.2 mm. 10 cm long.
- Reinforced fiberglass cambric.
- Rechargeable battery 3.7 V.
- Battery compartment for this battery.
- A piece of round wood.
- Switch.
- Thin single-core wire 0.3-06, diameter (multi-core can be unraveled).
Making a mini soldering iron
Let's take a thick single-core wire with a cross-section of 2 mm in diameter. We will remove the insulation using a clerical knife or another method.
Then we take a telescopic antenna from any receiver, joystick or walkie-talkie and disassemble it. We need to find a tube into which our core from the wire will fit tightly. Once the antenna elbow is selected, the remaining parts can be removed.
Using a machine or manually with a file, we sharpen a thick strand of wire into a cone - this will become a soldering tip.
Cut about 1.8 cm with a hacksaw.
We cut off about 4 cm of the tube that we took from the antenna.
We take nichrome wire and measure 10 centimeters, cut off the rest.
Let's take a wire with a diameter of 1.2-1.8 mm. It is only needed for winding the coil; we will not need it later. The material doesn't matter. We wind the nichrome wire, leaving the ends about 1 centimeter.
Then take a thin strand from a copper wire, fold it in half and twist it with wire cutters.
We will thread the nichrome wire into the resulting eye and twist the end around the copper wire. And let's put it aside for now.
Let's take the tube from the antenna and thread the reinforced fiberglass casing inside the tube. If your cambric turns out to be larger in diameter, you can make a longitudinal cut and adjust it to the diameter of the tube.
We take everything together and put it together.
We thread a nichrome coil with wire into the cambric so that only a 1 cm long wire sticks out from the outside. From this centimeter we make a turn around the thermal insulation. This will be a thermocouple.
We take our tip and insert it into the tube from the antenna.
On the other hand, we insert our thermoelement all the way.
Take a round piece of wood and cut off about 2-3 cm.
Drill a hole in the center for the soldering element.
We mill a groove from this hole using the same drill, see photo.
Insert the soldering tip with the thermoelement assembly. And bend the tail into the groove.
We drill more holes, but with a smaller diameter and a little further from the center.
We take a thin copper wire and make a loop on the tube and bend it. This will be the second contact.
We insert everything into a round piece of wood.
Portable homemade USB soldering iron. Convenient and compact DIY soldering iron, powered by USB. Heats up and cools down quickly. Solder wherever you want by connecting a power bank.
Now there are a lot of different homemade soldering irons on the Internet. I decided to do something average, simple in execution and take the best of the homemade products I looked at.
The goal was to make the soldering iron compact, heat up quickly, lightweight and, most importantly, portable.
I decided to abandon the built-in battery to reduce weight and ease of use. The wire doesn't interfere. You can screw in a light bulb to illuminate the work area with a separate button.
To make a homemade product we will need:
1. Wood block(I took 7cm x 1.5cm x 1.5cm);
2. Copper wire with a diameter of 1 mm and a length of 9 cm (longer is possible);
3. Nichrome wire 7cm long (taken from an old soldering iron);
4. A bolt or self-tapping screw with a flat head (you can add a washer);
5. Switch;
6. 2 thin wires (I took twisted pair);
7. USB plug with a wire of the length you need;
8. Electrical tape, heat shrink and super glue;
9. Fiberglass.
From the tools:
1. Soldering iron;
2. Pliers;
3. Screwdriver for a bolt or self-tapping screw.
Making a soldering iron
The first step is to prepare the block. Adjust the length so that it is comfortable to hold, grind off the corners.
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We take copper wire with a diameter of 1 mm from 9 cm to 12 cm and bend the ring at one end with pliers so that a bolt or self-tapping screw can fit through.
We take a nichrome wire 7cm long and wind it in a spiral (more tightly, but so as not to touch each other) onto the straight end of the copper wire, leaving workplace for soldering. I took the photo in the article when I didn’t have fiberglass on hand. Keep in mind that there must be insulation, although everything worked fine for me without it.
We screw two copper wires to nichrome wire as shown in the photo.
Glue the switch to the block, solder the wires to the switch and wrap the bottom of the block with electrical tape to secure the wires.
We tape the wire to the block with electrical tape and that’s it.
Let's start the soldering iron test.
