Hakko t12 which tips to choose. Soldering station on STC for Hakko T12 tips

Assembling a soldering station on Hakko T12

The article briefly describes the prerequisites for choosing a soldering station specifically based on Hakko T12 tips, then provides a comparative analysis of several versions available on the market, and also discusses some features of assembling the soldering station and its final setup.

Why all the hype around the Hakko T12?

To understand why many radio amateurs have recently become so interested in these Chinese stations, you need to start from afar. If you have already come to this decision yourself, you can skip this chapter.

For anyone starting to learn to solder, the first question that arises is choosing a soldering iron. Many people start with cheap fixed-power soldering irons available at the nearest hardware store. Of course, some simple work, such as soldering wires, can be done even with a Soviet soldering iron with a copper tip, especially if you have the skill. However, anyone who has tried to solder something more technologically advanced with such a soldering iron, the problems become obvious: if the soldering iron is too weak (40W or less) - some parts, for example the leads connected to the ground pad, are very inconvenient to solder, and if the soldering iron is powerful (50W or more) ) - it overheats very quickly and instead of soldering, ritual burning of the tracks occurs. Based on the above, even if you are just learning to solder, it is advisable to still buy a soldering iron with the ability to adjust the temperature. However, more often than not, soldering irons with simple controls built into the handle are products of extremely low quality, so if you are already wondering about choosing a normal soldering iron, you should most likely look in the direction of soldering stations.

Most often, the next question is which soldering station to choose. There may be variations here, since professionals mainly work with rather bulky stations combined with a soldering gun, such as PACE, ERSA, or, at worst, Lukey. I don’t need a hair dryer at home, but at the same time I want to have a reliable, powerful and compact station with the ability to adjust. Since the workplace is not made of rubber, the station must be really small, which is why many stations are outsized. Plus, of course, you always want to stay within a reasonable budget. And here our Chinese friends come onto the scene with their stations designed to work with tips from the Japanese company Hakko. Original soldering stations from this brand cost some inadequate money, but Chinese crafts for these tips, oddly enough, are of fairly high quality, at a very reasonable price.

So, why the stings from Hakko? Their main trump card is a ceramic heater combined with a temperature sensor. Actually, for a finished soldering station, all that remains is to “add” a PID controller and sufficient power to such a tip, which allows you to achieve fast heating and high-quality maintenance of the set temperature. Well, wrap it all in a convenient case. Actually, in soldering station designs, which can be found in abundance on Aliexpress for queries like "diy hakko t12", all this is implemented, and the Chinese usually include one or two Hakko tips in the kit (there is an opinion that these are mostly copies, however, even the copies have the same quality).

Choosing a kit for assembly

If you have already tried to search for a similar soldering iron on Ali, you were probably surprised by the variety of options that the search produces.

At the beginning of 2018, searches on Ali most often come up with offers from the “firms” Quicko, Suhan and Ksger. Moreover, in the descriptions they sometimes even refer to each other, so it is quite obvious that this is essentially the same thing, so further, if possible, I will skip specific names of the “manufacturer”, referring only to the versions of specific stations, because a quick analysis of photographs suggests that if the versions are the same, then the circuit design is approximately the same.

In fact, there are generally not as many variations as it might seem at first glance. I will describe the main significant differences:

An approximate table of soldering iron power, depending on the voltage of the power supply:

• At 12V - 1.5A (18 W)
• At 15V - 1.88A (28 W)
• At 18V - 2.25A (41 W)
• At 20V - 2.5A (50 W)
• At 24V (max!) - 3A (72 W)

note, for some versions it is indicated that when using a power supply higher than 19V, it is advisable to unsolder a 100 Ohm resistor labeled something like “20-30V R-NC”. This resistor is paralleled with a more powerful 330 Ohm resistor and together they form one 77 Ohm resistor connected in front of the 78M05 chip. Having soldered off 100 Ohms, we will leave one resistor at 330. This was done in order to reduce the voltage drop on this regulator at a high input voltage - obviously to increase its reliability and durability. On the other hand, by raising the resistance to 330 we will also limit the maximum current along the +5V line. At the same time, taking into account that the 78M05 itself can easily handle even 30V at the input, I would not solder off 100 Ohms completely, but would replace this resistor with something in the range of 200-500 Ohms (the higher the voltage, the higher the value). Or you can not touch this resistor at all and leave it as is.

So, we’ve decided on the general package, now let’s take a closer look at the boards themselves of various versions.

Comparison of some versions

Nowadays you can find on sale a car from various stations under different names, it is unclear how they differ. I already wrote above that I bought myself a station on STC, so I will only compare the versions on this controller.

The circuit design of all boards is quite similar, minor nuances may differ. I found a diagram online, drawn by a Wwest user from ixbt.com, for the version F. In principle, it is quite enough to understand the operation of the station.

Mini STC T12 ver.F soldering station diagram

To begin with, under the spoilers below are comparative photos of two versions of the Mini STC T12 ver.E And ver.F :

Appearance of Mini STC T12 ver.E

Appearance of Mini STC T12 ver.F

The first thing that catches your eye is the absence of an electrolytic capacitor between the indicator and the encoder in the version F, as well as a slightly smaller number of parts. It seems that the electrolyte was replaced with ceramic closer to the output of the 78M05, but it is difficult to estimate the capacity of the ceramic from a photograph. If there is something like 10 uF or more, then, given the small load power, this is quite acceptable. In the diagram for the version F This capacitor is designated as 47 uF tantalum, probably the author of the circuit had a board from Diymore (see below). Also, in the newer version, the contact pads for the NTC thermistor were changed (in the version E it is designated as R 11) to a larger standard size, and they reduced the number of individual resistors by assembling them into another assembly - this simplifies the purchase of parts, reduces the likelihood of installation errors and increases the overall manufacturability, which can clearly be considered a plus. In addition, the electrolytic capacitor, which could be dispensed with, can also be written down as a minus for the version E.

In summary, the following can be concluded as an intermediate conclusion: if you have the opportunity to replace the electrolyte with a polymer, then it is better to take the version E. If you don’t care what to change, it’s better to buy more capacious ceramics and take the version F. And if you don’t want to change anything at all, then the question comes down to what will fail faster, the electrolyte, or the controller with unstable power supply. Considering that the version F The overall manufacturability is higher, I would probably recommend it.

Two more board options are less common - from Ksger and Diymore, and from them it is clear that the board routing has been further developed.

Appearance of Diymore Mini STC T12 (version unknown)

Appearance of Ksger Mini STC T12 LED (version unknown)

Personally, I like the version from Ksger best - it’s clear that it was created with love. However, the previously mentioned capacitor here is definitely no more than 1206 - there are practically no 10 μF ceramics available on the market for this standard size with a voltage of more than 20 V, so most likely, for the sake of economy, something small is worth it here. This is a minus. In addition, the AOD409 power mosfet was replaced with some kind of transistor in a SOIC package, which, in my opinion, has worse heat transfer.

The version from Diymore contains tantalum and the usual AOD409 in the DPAK case, so despite the fact that it is less visually attractive, it is clearly preferable when choosing. Unless you are ready to solder these elements yourself.

Total: If you don’t care at all what to buy and you don’t want to resolder anything after purchasing, I would advise looking for a version similar to the photo of the board from Diymore, or, if you’re too lazy to look for it, take the version F and change capacitors as described above.

Assembly

In general, assembling the soldering iron is trivial, except for the fact that for assembly you will need another soldering iron (smile). However, as usual, there are several nuances.

Soldering iron handle assembly. The connector contacts on the board and in the handle may have different markings. This is unlikely to be a problem, since there are only five wires anyway:

• Two power wires - plus and minus
• Thermal sensor wire
• Two vibration sensor wires (the order is not important)

On the controller board, the temperature sensor wire is most often labeled with one letter E. One of the vibration sensor contacts is labeled SW, and the second can be soldered to any hole marked minus " − ". In fact, I don’t really understand why there was a separate wire from the handle for the minus of the sensor, given that it still goes to the ground, but perhaps this was done for less noise.

If the contacts on your handle are not labeled in any way, it is enough to know that there are only three contacts on the tip itself: plus (closest to the end on the tip), then there is a minus and the output of the temperature sensor. For clarity, I buried the diagram with Ali.

The Chinese sometimes label the thermocouple output as ground, but in the controller itself E is connected to ground - as far as I understand, this is not entirely correct, although I’m too lazy to figure it out, and I don’t have a ground anyway.

In some versions, in addition to the vibration sensor, you also need to solder a capacitor into the handle. I don’t know for sure, but the condenser may be between the plus and minus of the heater - so that it makes less noise in the RF range. It could also be a conductor between the temperature sensor and the ground - again, so that the temperature sensor readings are smoother and less noisy. I don’t know how practical all this is at all - for example, there was no room for a capacitor in my pen at all. In addition, some users wrote that the accuracy of thermal stabilization with the capacitor terminals closed was higher. In general, if this capacitor is provided in your model, you can try this and that.

Judging by reviews on the Internet, some pens, in addition to a capacitor and a vibration sensor, also had a thermistor, supposedly to control the temperature of the cold end. However, then the manufacturers realized that it was logical to place the cold side sensor directly on the controller board and they no longer suffer from such garbage.

About the vibration sensor. As a vibration sensor in such stations, either SW-18010P vibration sensors (rarely) or SW-200D (mostly) are used. Some craftsmen also use mercury sensors - I am not at all a supporter of using mercury in households, so I will not discuss this approach here.

SW-18010P is a regular spring in a metal case. They write that such a sensor is much less convenient for a soldering iron than the SW-200D, which is a simple metal “cup” with two balls inside. I had two SW-200Ds in my kit, and I advise you to use them too.

A vibration sensor is needed to automatically switch the station to standby mode, in which the temperature of the tip decreases until the soldering iron is picked up again. The function is ultra-convenient, so I highly recommend that you do not give up the sensor.

Judging by the picture with the connection diagram of the handle, the Chinese advise soldering the sensor with a silver pin towards the tip. Actually, that’s exactly what I did and everything works very conveniently for me.

However, for some reason this sensor does not work normally - they write that the soldering iron has to be shaken to wake it up from sleep mode and they explain this with a picture from which it is obvious that if the sensor is tilted towards the handle, there can be no contact until it is not shake it. In general, if in your case the station does not wake up from sleep mode when you just take the soldering iron, try re-soldering the vibration sensor with the reverse side.

There is one more hint - some cunning people advise soldering two sensors in parallel and in different directions, then everything should work in any position of the soldering iron. Indirectly, this assumption is confirmed by the fact that in many kits the Chinese put two sensors, and on the handle itself there are two places nearby where it is very convenient to solder them - most likely for this very purpose. Everything worked right away for me, so I didn’t check the hint.

If you still don’t want to use the auto-shutdown function at all or you don’t like the way the vibration sensor rattles, you can turn it off simply by closing SW and + on the controller board, and do not solder the wires going to the handle at all.

About the body. As I wrote above, I chose the standard aluminum housing that is offered for these stations. And on the whole, I am satisfied with my choice. There are several points to pay attention to.

First, you need to somehow secure the power supply to the case. I solved this simply by drilling four holes in the case and attaching the power supply to the screws. In my case, the power supply was simply a separate board with radiators, and since... The case is aluminum, it was necessary to make some bosses so that the power supply board does not lie directly on the case. To do this, I cut out two strips of plexiglass, in which I drilled two holes for screws, and this solved the problem. You can, for example, cut out insulating rings of the required height from some polymer tube, but it seemed to me that the idea with strips of plexiglass was simpler.

Secondly, I relied on the gloomy Chinese genius and did not check the dimensions of the case and power supply. This was a mistake. As you can judge from the photo below, it turned out that after installing the controller, my unit fits into the case almost flush, which is not good. I had to unsolder the output terminals of the unit and solder the wires to the controller power connector directly onto the power supply board. If there were no connector on the controller board, the unit would have been non-separable, which would have been much less convenient. On the 220V side I added additional insulation with heat shrink and a drop of hot glue. You can also see a strip of hot-melt adhesive on the 220V connector - so that it dangles less.

In general, despite the fact that everything fit with minimal gaps, it turned out acceptable, but a sediment remained.

About the power supply and controller improvements. As I wrote above, I had a version station E with regular electrolyte. Everyone knows that ordinary electrolytes tend to dry out over time, so I replaced the electrolyte with a polymer capacitor that was lying around. I also soldered the encoder contacts - many users noticed that without this the button in the encoder did not work (if you noticed, in the photographs given earlier, you can see that on three of the four boards the central contact of the encoder is not soldered at all).

The power supply that was sent to me complete with the station was defective - one of the diodes of the “hot part” was soldered with the wrong polarity, which is why the power mosfet burned out already the third time the soldering station was turned on and I had to figure out what the reason was, spending another half a day on repairing the power supply . It was also lucky that the PWM Controller did not die after the mosfet. What I mean is that it may make sense to assemble the block yourself, or use one that has already been tested.

As a minimal modification to the power supply, low-capacity ceramics from those lying around were soldered in parallel to the output electrolytes, and the interwinding capacitor was also replaced with a higher voltage one.

After all the fiddling around, the result was a fairly powerful and reliable unit and controller, although clearly more effort was spent than I had planned.

Setup after assembly

The station does not have many settings; most of them can be configured once.

Directly while the soldering iron is operating, you can change the temperature adjustment step and perform software temperature calibration - menu items P10 and P11. This is done as follows - press the encoder knob and hold for about 2 seconds, get to point P10, briefly press to change the order (hundreds, tens, units), turn the knob to change the value, then press again for 2 seconds. hold the encoder knob, the value is saved, and we go to point P11, etc., the next 2s. pressing returns to operating mode.

To get to the extended software menu, you need to hold down the encoder knob and, without releasing it, apply power to the controller.

The most common menu is the following (brief description, default values ​​in parentheses):

• P01: ADC reference voltage (2490 mV - TL431 reference)
• P02: NTC setting (32 sec)
• P03: op-amp input offset voltage correction (55)
• P04: thermocouple gain factor (270)
• P05: PID proportionality gain pGain (-64)
• P06: integration factor PID iGain (-2)
• P07: PID differentiation factor dGain (-16)
• P08: time to fall asleep (3-50 minutes)
• P09:(in some versions - P99) reset settings
• P10: temperature setting step
• P11: thermocouple amplifier coefficient

To move between menu items, you need to briefly press the encoder button.

The following menu configuration is also sometimes encountered:

• P00: restore default settings (select 1 to restore)
• P01: thermocouple amplifier coefficient (default 230)
• P02: thermocouple amplifier bias voltage, I don’t know what it is, the seller advises not to change without measurements (default value 100)
• P03: thermocouple °C/mV ratio (default value 41, it is recommended not to change)
• P04: temperature adjustment step (0 locks tip temperature)
• P05: time to fall asleep (0-60 minutes, 0 - disable falling asleep)
• P06: shutdown time (0-180 minutes, 0 - shutdown function inactive)
• P07: temperature correction (default +20 degrees)
• P08: wake-up mode (0 - to wake up from sleep you can rotate the encoder or shake the knob, 1 - you can only wake up from sleep by rotating the encoder)
• P09: something related to the heating mode (measured in degrees)
• P10: time parameter for the previous item (seconds)
• P11: the time after which the “automatic saving of settings” should work and exit the menu.

It is worth noting that, unlike board tracing, there can be many more firmware options, so there is no single correct description of menu items - there can be many options, even in the same version of the board they can differ. Is it possible to still recommend taking models with a text display, and if it doesn’t exist, look at the recommendations of the seller from whom you bought it.

conclusions

Conditional disadvantages:

1. Out of the box, the temperature of the tip does not necessarily correspond to reality; I had to tinker a little with the thermocouple to get an acceptable result.
2. For each tip you have to calibrate the station again. I don’t change tips often, it’s not critical for me. In addition, some firmware versions provide the ability to save multiple profiles, so this minus is not relevant in some cases.

Total: Overall, the station works great and I think that the hemorrhoids with the assembly are completely worth it. A little later I will compare several different stations, and there I will describe all the advantages/disadvantages.

That's all, thanks for reading!

Reading local reviews, I have repeatedly thought about buying a soldering iron with a T12 tip. For a long time I wanted something portable on the one hand, powerful enough on the other hand, and, of course, maintaining the temperature normally.
I have relatively many soldering irons, purchased at different times and for different tasks:
There are very ancient EPSN-40 and “Moskabel” 90W, a slightly newer EMP-100 (hatchet), and a completely new Chinese TLW 500W. The last two retain temperature especially well (even when soldering copper pipes), but soldering microcircuits with them is not very convenient :). An attempt to use the ZD-80 (a pistol with a button) did not work - neither power nor normal temperature maintenance. Other “electronic” little things like Antex cs18/xs25 are only suitable for very small things, and they don’t have built-in adjustments. About 15 years ago I used den-on's ss-8200, but the tips are very tiny, the temperature sensor is far away and the temperature gradient is huge - despite the stated 80W, the tip doesn't even feel like a third.
As a stationary option, I’ve been using Lukey 868 for 10 years now (it’s practically 702, only with a ceramic heater and some other little things). But there is no portability at all; you can’t take it with you in your pocket or small bag.
Because At the time of purchase, I was not yet sure “whether I needed it”, I took the minimal budget option with a K-tip and a handle that was as similar as possible to the usual soldering iron from Lukey. It is possible that for some it does not seem very convenient, but for me it is more important that the handles of both used soldering irons fit familiarly and equally in the hand.
The further review can be roughly divided into two parts - “how to make a device from spare parts” and an attempt to analyze “how this device and the controller firmware work.”
Unfortunately, the seller removed this particular SKU, so I can only provide a link to a snapshot of the product from the order log. However, there are no problems finding a similar product.

Part 1 - design

After a mock-up performance check, the question arose about choosing a design.
There was an almost suitable power supply (24v 65W), almost 1:1 in height with the control board, slightly narrower than it and about 100mm long. Considering that this power supply fed some kind of dead (not through its fault!) connected and not cheap Lucent piece of hardware, and its output rectifier contains two diode assemblies for a total of 40A, I decided that it is not much worse than the one common here Chinese at 6A. At the same time, there will be no lying around.
Testing on a time-tested load equivalent (PEV-100, twisted to approximately 8 ohms)


showed that the power supply practically does not heat up - after 5 minutes of operation, the key transistor, despite its insulated housing, heated up to 40 degrees (a little warm), the diodes are warmer (but do not burn your hand, it is quite comfortable to hold), and the voltage is still 24 volts with in kopecks. The emissions increased to hundreds of millivolts, but for this voltage and this application this is quite normal. Actually, I stopped the experiment because of the load resistor - about 50W was released on its smaller half and the temperature exceeded a hundred.
As a result, the minimum dimensions were determined (power supply + control board), the next stage was the housing.
Since one of the requirements was portability, even the ability to stuff it into pockets, the option of ready-made cases was no longer needed. The available universal plastic cases were not at all suitable in size, the Chinese aluminum cases for T12 for jacket pockets were also too big, and I didn’t want to wait another month. The option with a “printed” case did not work - neither strength nor heat resistance. Having assessed the possibilities and remembering my pioneer youth, I decided to make one from an ancient one-sided foil fiberglass laminate that had been lying around since the times of the USSR. Thick foil (the micrometer on a carefully smoothed piece showed 0.2mm!) still did not allow etching tracks thinner than a millimeter due to side etching, but for the case it was just right.
But laziness, coupled with a reluctance to create dust, categorically did not approve of sawing with a hacksaw or cutter. After assessing the available technological capabilities, I decided to try the option of sawing textolite using an electric tile cutter. As it turned out, it is an extremely convenient option. The disc cuts fiberglass without any effort, the edge is almost perfect (you can’t even compare it with a cutter, hacksaw or jigsaw), the width along the length of the cut is also the same. And, importantly, all the dust remains in the water. It is clear that if you need to saw off one small piece, then it will take too long to unfold the tile cutter. But even this small body required a meter of cutting.
Next, a case with two compartments was soldered - one for the power supply, the second for the control board. Initially, I didn't plan to split. But, as with welding, plates soldered into a corner tend to reduce the angle as they cool, and an additional membrane is very useful.
The front panel is bent from aluminum in the shape of the letter P. There is a thread cut in the upper and lower bends for fixation in the case.
The result was this (I’m still “playing” with the device, so the painting is still very rough, from the remains of an old spray can and without sanding):

The overall dimensions of the case itself are 73 (width) x 120 (length) x 29 (height). The width and height cannot be made smaller, because... The dimensions of the control board are 69 x 25, and finding a shorter power supply is also not easy.
At the back there is a connector for a standard electrical wire and a switch:


Unfortunately, the black microswitch was not in the trash; I will have to order one. On the other hand, white is more noticeable. But I specifically set the connector to standard - this allows, in most cases, not to take an additional wire with you. Unlike the option with a laptop socket.
Bottom view:

The black rubber-like insulator is left over from the original power supply. It is quite thick (a little less than a millimeter), heat-resistant and very difficult to cut (hence the rough cutout for the plastic spacer - it almost didn’t fit). It feels like asbestos impregnated with rubber.
To the left of the power supply is the rectifier radiator, to the right is the key transistor. In the original PSU, the heatsink was a thin strip of aluminum. I decided to “aggravate” it just in case. Both heatsinks are isolated from the electronics, so they can freely adhere to the copper surfaces of the case.
An additional heatsink for the control board is mounted on the membrane; contact with d-pak cases is ensured by a thermal pad. There is not much benefit, but everything is better than air. To prevent a short circuit, I had to slightly bite off the protruding contacts of the “aviation” connector.
For clarity, a soldering iron next to the body:

Result:
1) The soldering iron works approximately as advertised and fits well in jacket pockets.
2) The following items have been disposed of in the old trash and are no longer lying around: a power supply, a piece of fiberglass from 40 years ago, a can of nitro enamel from 1987, a microswitch and a small piece of aluminum.

Of course, from the point of view of economic feasibility, it is much easier to buy a ready-made case. Even though the materials were practically free, “time is money.” It’s just that the task of “doing it cheaper” didn’t appear on my list of tasks at all.

Part 2 - Operational Notes

As you can see, in the first part I did not mention at all how it all works. It seemed to me advisable not to confuse the description of my personal design (rather “collective-farm homemade” in my opinion) and the functioning of the controller, which is identical or similar for many.

As a bit of a preliminary warning, I want to say:
1) Different controllers have slightly different circuitry. Even outwardly identical boards may have slightly different components. Because I only have one specific device of mine, I can in no way guarantee a match with others.
2) The controller firmware that I analyzed is not the only one available. It is common, but you may have different firmware that functions differently.
3) I do not at all lay claim to the laurels of the discoverer. Many points have already been covered previously by other reviewers.
4) Next there will be a lot of boring letters and not a single funny picture. If you are not interested in the internal structure, stop here.

Design overview

Further calculations will be largely related to the controller circuitry. To understand its operation, an exact diagram is not necessary; it is enough to consider the main components:
1) Microcontroller STC15F204EA. An unremarkable chip from the 8051 family, noticeably faster than the original (the original was 35 years ago, yes). Powered by 5V, has on board a 10-bit ADC with a switch, 2x512 bytes nvram, 4KB program memory.
2) A +5V stabilizer, consisting of 7805 and a powerful resistor to reduce heat generation (?) on 7805, with a resistance of 120-330 Ohms (different on different boards). The solution is extremely cost effective and heat efficient.
3) Power transistor STD10PF06 with wiring. Operates in key mode at low frequency. Nothing special, old man.
4) Thermocouple voltage amplifier. The trimmer resistor regulates its gain. It has input protection (from 24V) and is connected to one of the inputs of the MK ADC.
5) Reference voltage source on TL431. Connected to one of the inputs of the MK ADC.
6) Board temperature sensor. Also connected to the ADC.
7) Indicator. Connected to MK, operates in dynamic indication mode. I suspect that one of the main consumers is +5V
8) Control knob. Rotation adjusts temperature (and other parameters). The button line in many models is not sealed or cut. If connected, it allows you to configure additional parameters.

As you can easily see, all functioning is determined by the microcontroller. I don’t know why the Chinese are installing just this one, it’s not very cheap (about $1, if you take several pieces) and it’s close in terms of resources. In typical Chinese firmware, literally a dozen bytes of program memory remain free. The firmware itself is written in C or something similar (the obvious tails of the library are visible there).

Controller firmware operation

I don’t have the source code, but IDA is still here :). The mechanism of operation is quite simple.
At initial startup, the firmware:
1) initializes the device
2) loads parameters from nvram
3) Checks whether the button is pressed, if it is pressed, it waits for it to be released and launches the advanced parameters settings subsection (Pxx). There are many parameters, if you don’t understand, then it’s better not to touch them. I can post the layout, but I'm afraid of causing problems.
4) Displays “SEA”, waits and starts the main work cycle

There are several operating modes:
1) Normal, normal temperature maintenance
2) Partial energy saving, temperature 200 degrees
3) Complete shutdown
4) Setting mode P10 (temperature setting step) and P4 (thermocouple op-amp gain)
5) Alternative control mode

After startup, mode 1 works.
When you briefly press the button, you switch to mode 5. There you can turn the knob to the left and go to mode 2 or to the right - increase the temperature by 10 degrees.
A long press switches to mode 4.

In previous reviews there was a lot of debate about how to properly install a vibration sensor. Based on the firmware I have, I can say unequivocally - it makes no difference. Entering partial energy saving mode occurs when there is no changes the state of the vibration sensor, the absence of significant changes in the temperature of the tip and the absence of signals from the handle - all this for 3 minutes. Whether the vibration sensor is closed or open is completely unimportant; the firmware only analyzes changes in state. The second part of the criterion is also interesting - if you solder, then the temperature of the tip will inevitably fluctuate. And if a deviation of more than 5 degrees from the set value is detected, there will be no exit to the energy saving mode.
If the energy saving mode lasts longer than specified, the soldering iron will turn off completely and the indicator will show zeros.
Exit from energy-saving modes - by vibration or by the control knob. There is no return from full to partial energy saving.

The MK is engaged in maintaining the temperature in one of the timer interrupts (there are two of them, the second deals with the display and other things. Why this was done is unclear - the interrupt interval and other settings are the same, it would have been possible to get by with a single interrupt). The control cycle consists of 200 timer interrupts. At the 200th interruption, the heating is necessarily turned off (as much as 0.5% of power!), a delay is performed, after which the voltages from the thermocouple, temperature sensor and reference voltage from TL431 are measured. Next, all this is converted into temperature using formulas and coefficients (partially specified in nvram).
Here I will allow myself a small digression. Why there is a temperature sensor in this configuration is not entirely clear. If properly organized, it should provide a temperature correction at the cold junction of the thermocouple. But in this design, it measures the temperature of the board, which has nothing to do with the required one. It either needs to be transferred to a pen, as close as possible to the T12 cartridge (and another question is where in the cartridge the cold junction of the thermocouple is located), or thrown away completely. Perhaps I don’t understand something, but it seems that the Chinese developers stupidly ripped off the compensation scheme from some other device, completely not understanding the principles of operation.

After measuring the temperature, the difference between the set temperature and the current temperature is calculated. Depending on whether it is large or small, two formulas work - one is large, with a bunch of coefficients and delta accumulation (those interested can read about the construction of PID controllers), the second is simpler - with large differences, you need to either heat it up as much as possible or turn it off completely (depending on from the sign). The PWM variable can have a value from 0 (disabled) to 200 (fully enabled) - according to the number of interruptions in the control cycle.
When I just turned on the device (and had not yet gotten into the firmware), I was interested in one thing - there was no jitter of ± a degree. Those. The temperature either remains stable or jumps by 5-10 degrees at once. After analyzing the firmware, it turned out that it apparently always trembles. But if the deviation from the set temperature is less than 2 degrees, the firmware shows not the measured temperature, but the set temperature. This is neither good nor bad - the jittery low order is also very annoying - you just need to keep it in mind.

Concluding the conversation about the firmware, I want to note a few more points.
1) I haven’t worked with thermocouples for about 20 years. Maybe during this time they have become more linear;), but before, for somewhat accurate measurements and if possible, a nonlinearity correction function was always introduced - with a formula or table. Here this is not the case at all. Only the zero offset and slope angle can be adjusted. Maybe all cartridges use high-linearity thermocouples. Or the individual scatter in different cartridges is greater than the possible group nonlinearity. I would like to hope for the first option, but experience hints at the second...
2) For a reason unknown to me, inside the firmware the temperature is set as a fixed-point number with a resolution of 0.1 degrees. It is quite obvious that due to the previous comment, 10-bit ADC, incorrect cold end correction, unshielded wire, etc. The real accuracy of measurements will not be even 1 degree. Those. It looks like it was ripped off again from some other device. And the complexity of the calculations has increased slightly (you have to repeatedly divide/multiply 16-bit numbers by ten).
3) The board has Rx/TX/gnd/+5v pads. As far as I understand, the Chinese had special firmware and a special Chinese program that allows you to directly receive data from all three ADC channels and configure PID parameters. But there is none of this in the standard firmware; the pins are intended exclusively for uploading firmware to the controller. The pouring program is available, works through a simple serial port, only TTL levels are needed.
4) The dots on the indicator have their own functionality - the left one indicates mode 5, the middle one indicates the presence of vibration, the right one indicates the type of temperature displayed (set or current).
5) 512 bytes are allocated to record the selected temperature. The entry itself is made correctly - each change is written to the next free cell. As soon as the end is reached, the block is completely erased, and writing is done to the first cell. When turned on, the farthest recorded value is taken. This allows you to increase the resource by a couple of hundred times.
Owner, remember - by rotating the temperature setting knob, you waste the irreplaceable resource of the built-in nvram!
6) For other settings, the second nvram block is used

Everything is with the firmware, if you have any additional questions, ask.

Power

One of the important characteristics of a soldering iron is the maximum heater power. It can be assessed as follows:
1) We have a voltage of 24V
2) We have a T12 tip. The cold resistance of the tip I measured is just over 8 ohms. I got 8.4, but I cannot claim that the measurement error is less than 0.1 Ohm. Let's assume that the real resistance is no less than 8.3 Ohms.
3) Resistance of the STD10PF06 key in the open state (according to the datasheet) - no more than 0.2 Ohm, typical - 0.18
4) Additionally, you need to take into account the resistance of 3 meters of wire (2x1.5) and connector.

The total resistance of the circuit in a cold state is at least 8.7 Ohms, which gives a maximum current of 2.76A. Taking into account the drop on the key, wires and connector, the voltage on the heater itself will be about 23V, which will give a power of about 64 W. Moreover, this is the maximum power in a cold state and without taking into account the duty cycle. But don’t be too upset - 64 W is quite a lot. And given the design of the tip, it is enough for most cases. When checking the performance in constant heating mode, I placed the tip of the tip in a mug of water - the water around the tip was boiling and steaming very vigorously.

But an attempt to save money using a power supply from a laptop has very questionable effectiveness - an apparently insignificant decrease in voltage leads to the loss of a third of the power: instead of 64 W, about 40 W will remain. Is the $6 saving worth it?

If, on the contrary, you try to squeeze the declared 70W out of the soldering iron, there are two ways:
1) Slightly increase the power supply voltage. It is enough to increase it by only 1V.
2) Reduce the circuit resistance.
Almost the only option to slightly reduce the circuit resistance is to replace the key transistor. Unfortunately, almost all p-channel transistors in the package used and for the required voltage (I wouldn’t risk setting it to 30V - the margin would be minimal) have similar Rdson. And that would be doubly wonderful - at the same time, the controller board would heat up less. Now in maximum heating mode, about a watt is released on the key transistor.

Accuracy/stability of temperature maintenance

In addition to power, stability of temperature maintenance is no less important. Moreover, for me personally, stability is even more important than accuracy, because if the value on the indicator can be determined experimentally - I usually do so (and it is not very important that when the setting is 300 degrees, the real value on the tip is 290), then instability cannot be overcome in this way . However, it feels like the temperature stability on the T12 is noticeably better than on the 900 series tips.

What makes sense to change in the controller

1) The controller is heating up. Not fatal, but more than desirable. Moreover, it is mainly not the power part that heats it, but the 5V stabilizer. Measurements showed that the current at 5V is about 30 mA. 19V drop at 30mA gives approximately 0.6W of continuous heating. Of this, about 0.1 W is released at the resistor (120 Ohm) and another 0.5 W is released at the stabilizer itself. The consumption of the rest of the circuit can be ignored - only 0.15 W, of which a noticeable part is spent on the indicator. But the board is small and there is simply nowhere to put the step-down - unless on a separate board.

2) Power switch with high (relatively high!) resistance. Using a switch with a resistance of 0.05 Ohm would eliminate all problems with its heating and add about a watt of power to the cartridge heater. But the case would no longer be a 2mm dpak, but at least one size larger. Or even change the control to the n-channel.

3) Transfer ntc to pen. But then it makes sense to move the microcontroller, the power switch and the reference voltage there.

4) Expansion of firmware functionality (several sets of PID parameters for different tips, etc.). Theoretically it’s possible, but personally it’s easier (and cheaper!) for me to re-create it on some younger stm32 than to trample it into existing memory.

As a result, we have a wonderful situation - a lot of things can be remade, but almost any rework requires throwing out the old board and making a new one. Or don’t touch it, which is what I’m leaning towards for now.

Conclusion

Does it make sense to switch to T12? Don't know. For now I'm only working with the T12-K tip. For me, it is one of the most universal - both the polygon heats well, and the lead comb can be soldered/unsoldered with an ersatz wave, and a separate lead can be heated with a sharp end.
On the other hand, the existing controller and the lack of means for automatically identifying a specific type of tip complicates working with the T12. Well, what stopped Hakko from putting some identifying resistor/diode/chip inside the cartridge? It would be ideal if the controller had several slots for individual settings of tips (at least 4 pieces) and when changing tips it would automatically load the necessary ones. And in the existing system, you can, at most, make a manual selection of the tip. Estimating the amount of work, you realize that the game is not worth the candle. And the cost of the cartridges is comparable to an entire soldering station (if you don’t buy the ones from China for $5). Yes, of course, you can experimentally display a table of temperature corrections and stick a sign on the lid. But you can’t do this with PID coefficients (on which stability directly depends). They must differ from sting to sting.

If we discard the dream thoughts, the following comes out:
1) If you don’t have a soldering station, but want to, it’s better to forget about 900 and take T12.
2) If you need it cheaply and you don’t really need precise soldering modes, it’s better to take a simple soldering iron with power adjustment.
3) If you already have a soldering station on the 900x, then a T12-K is enough - the versatility and portability are excellent.

Personally, I’m happy with the purchase, but I don’t yet plan to replace all the existing 900 tips with T12 ones.

This is my first review, so I apologize in advance for any roughness.

What is a sting? Hakko T12? This is a cartridge that includes a soldering iron tip, a heater and a thermocouple. Now they are gaining popularity and the Internet is full of articles about them. Due to the fact that they were repeated by the Chinese, prices for them on Ali are around $4, and on sale you can often buy them individually at a price of around $3. The range of these tips is wide, it is claimed that there are more than 80 models. (By the way, T15 are the same tips, fully compatible with T12)

I was also attracted to these stings after watching the reviews. One of the main points is fast heating. When you are debugging or repairing, you often need to solder one wire or replace some part, and waiting every time for the soldering iron to heat up is annoying, and keeping it on all the time, in addition to reducing the resource, does not make the air in the room cleaner. Here the heating takes place literally in ten seconds, i.e. By the time I dropped some flux and took tweezers, the soldering iron was already ready. It’s also not a bad opportunity to warm up large ranges.

Assemble everything correctly with a purchased soldering iron handle with quick replacement, etc. In terms of money, it’s not very justified, since a ready-made station like BK950D costs $35-40 on AliExpress.

Therefore, I decided to simplify everything as much as possible by refusing to change the tips. In principle, as a rule, only a couple of stings are used, rarely three. I decided to just make a couple of soldering irons to make a two-channel soldering station.

So I bought one T12-KU tip for testing for now.

The tip rod at the end has two contact strips, between them a heater with a resistance of 8 Ohms and a thermocouple are connected in series. Supply voltage up to 24V and current up to 3A. Maximum power is about 70W.

If you look from the far side of the heater, then first there is a plus, then a minus, and the body of the cartridge itself is the ground and serves to ground the tip.

I attached the wires to these belts with a simple twist and crimped them with several heat shrinks.

Two thickenings are visible on the sting shaft. After the second thickening from the tip of the sting, the rod has a low temperature, and here you can already handle it with your hands. At this point I wrapped paper with regular stationery glue.

If you have a ready-made handle for a soldering iron or a suitable tube, then you can already glue in the rod. But since I didn’t have anything on hand, I also glued the pen together from office paper.

Of course, after each layer of paper you need to let the glue dry. After complete drying, I crimped heat shrink on top to make it less dirty and more pleasant to hold.

At the back, to increase rigidity, I filled it with glue (there is literally not a large ring of glue there).

The temperature controller was made analog and was based on a circuit from Chinese regulators. The polarity of the heater is not indicated in the diagram; the plus of the heater is on top of the diagram, the minus is connected to the ground of the circuit.

I just remade it to fit the existing parts. I replaced the 7806 stabilizer with LM317, Q1 2N2222, Q2 AO4407 and added a protective diode D3. I provide a drawing of the printed circuit board, it is made on two-sided PCB, the other side is for an earthen polygon. All SMD resistors and ceramic capacitors are size 0805. Additional shunt capacitors are 0.1 µF, but you don’t have to install them. C4 size B.

The only missing part in this circuit is the P-Mosfet.

I also tried to remake the circuit for N-Mosfet, which are much easier to get or pick out.

WARNING. The circuit does not work when using LM358. I managed to launch it using the TL082 op-amp; he provided his version in the comments.

Zener diode D3 and transistor Q2 took the first ones available. Any zener diode for current >20mA and voltage 6V. A transistor for a voltage of more than 40V and a current of more than 6A (for a power supply of less than 20V, you can install Mosfet from old motherboards, they are usually for a voltage of 30V).

Resistor R15 and voltage source V1, this is the heater and thermocouple of the soldering iron.

So far I have assembled the board according to the Chinese version of the circuit and it looks like this when assembled.

Settings

The circuit requires almost no setup, but you need to connect the heater correctly and adjust the temperature range. Debugging must be carried out with the supply voltage reduced to 9 volts, otherwise, if turned on for a long time at 24V, the tip can become red hot. To determine the correct polarity of the heater connection, I broke the circuit near the variable resistor (I did not solder in the substring resistor) and turned on the regulator. If the soldering iron is turned on with the correct polarity, no power is supplied to it and the LED does not light up. Due to the drift of the op-amp zero, this behavior is possible even with incorrect polarity; to check this situation, warm the tip of the tip for half a second with a lighter. If the polarity is not correct, power will be supplied to the soldering iron continuously.

I had a 10k variable resistor available, so the ratings of the adjustment circuit are slightly different from the original; after adjustment, the adjustment range turned out to be from 260º to 390º. Perhaps I’ll decide to expand the range further by reducing the resistance of the low-resistance resistor R2.

Tests

The soldering iron performed quite well in operation. The heating rate turned out to be really high for about ten seconds (I’ll give you a video).

I didn’t see much of a miracle in terms of power, unless of course you compare it with cheap Chinese stations, which for the most part don’t solder, but just pick their snot. And this is quite at the level of simple, but branded stations.

I soldered the adapter with this soldering iron. Although for such a thin sting this is a perversion. Soldering such massive parts cannot be called comfortable; heat transfer is clearly not enough. The video turned out boring and long, so I decided not to post it.

In the end, overall I was quite pleased with the results.

Therefore, I plan to order another sting that is more massive, until I decide which type to choose, type BC or D.

And make a two-channel station from a computer power supply. There are plenty of articles about it; removing 20-24v and 6a from it also doesn’t seem to be a problem. I tried it on, and it seems that after removing unnecessary parts from the power supply board, two regulators will fit into the case. At the same time I'm going to use the unit's fan as an exhaust hood. Now I’m using a 12V fan with a piece of filter from a kitchen hood (the description stated that this felt is like activated carbon), but the thrust of one fan is a little insufficient and I plan to install two.

By the way, here is a view of today's fan that I use as an exhaust hood.

When I get around to doing it, I’ll show you what happened. For now, the soldering iron is simply connected to the laboratory unit. If you power one soldering iron, you can use a power supply, for example, from a laptop; mine from a burnt-out laptop produces 19V and 4.5A, which is quite enough for work.

I also provide a video demonstrating the heating speed of the soldering iron. Of course, for a more massive tip or at a lower supply voltage, the warm-up time may increase.

The list of elements shows the values ​​soldered on the board, the notes indicate the elements on the original circuit.

List of radioelements

Designation	Type	Denomination	Quantity	Note	Shop	My notepad
U1	Operational amplifier	LM358A	1			To notepad
U2	Linear regulator	LM317M	1	LM7806		To notepad
Q1	Bipolar transistor	2N2222A	1	9013		To notepad
Q2	MOSFET transistor	AO4407A	1	IRF9540		To notepad
D1-D3	Rectifier diode	1N4148	3	Diode D3 is missing in the original		To notepad
C2	Capacitor	10 nF	1			To notepad
C3	Capacitor	1 µF	1			To notepad
C4	Capacitor	22 µF	1	1 µF		To notepad
C5	Electrolytic capacitor	470 µF	1			To notepad
R1	Resistor	22 kOhm	1	30 kOhm		To notepad
R2	Resistor	39 Ohm	1	51 Ohm		To notepad
R3	Resistor	100 Ohm	1			To notepad
R4	Resistor	120 kOhm	1	100 kOhm		To notepad
R5, R6, R13	Resistor

Hakko T12 tips have recently become increasingly popular due to their high quality, ease of use and large assortment. In total, there are about 80 varieties of stings (more precisely, their tips), which is enough for absolutely any situation. Most users use at most 5-10 varieties in their work, but if necessary, you can always choose exactly the option that is required at the moment.

Features of Hakko T12 tips for soldering station

Tips of this type are primarily distinguished by a very high heating rate to working condition. On average, when using a more or less normal soldering station, this takes about 15 seconds (sometimes less). In addition, such products are equipped by default with a built-in temperature sensor. That is, if you have a normal soldering iron controller and an external temperature meter, you can configure them so that the temperature varies at a level of 7-10 o C, no more.

The next important point is ease of use. With most other tips, there is often a problem with dismantling. You have to spend quite a lot of time removing the tip and installing a new one. With tips like Hakko T12, this problem does not arise in principle. The entire replacement process takes about five seconds.

Products are supplied in a regular plastic bag. Each of them has three contacts, which are separated from each other by special plastic rings. The length of the sting can vary between 147-154 mm, much depends on the variety. In some cases they may be slightly longer or shorter. Each product has a tip code and its type (a sticker with these characteristics).

To work with a sting with a diameter of 5.5 millimeters, a voltage of 24 volts and a power of 70 watts will be required. They heat up to a temperature of 400 o C, but can be increased by another +50 degrees. True, this will lead to the fact that the sting will serve much less. And what is important, such tips can be easily combined with lead-free solders. All supplied products have tinned tips.

Popular types of Hakko T12 stings

It is simply pointless to list all the varieties of stings from this manufacturer. There are also a lot of options for their use, but there are several types that deservedly enjoy the highest popularity. Let's look at them in a little more detail.

So, the T12-K type tip vaguely resembles the tip of a stationery knife. Great for heating a large part or multiple contacts. You can also use it to cut synthetics and melt polyethylene.

In different sets of stings Hakko T12 There can be a wide variety of product variations. Before purchasing, it is recommended to clarify what exactly is included in the package and make the final decision after receiving such information.

The sharp stings of T12-D08, T12-B and T12-IL are similar to each other. The tip resembles an awl and the only difference lies in the exact sharpening angle of this or that variety and the overall diameter of the tip. Suitable for almost all standard soldering iron applications. Curved tips T12-JL02 vaguely resemble a hook and are used in cases where it is impossible to get close to the part directly. In general, for any hard-to-reach places.

T12-D4 and T12-D24 are devices similar to a chisel in their tip. The scope of application is extremely wide, but they are suitable for almost everything. And the last of the common variations: T12-BC2, T12-C4 and T12-C1. These are universal stings, the only difference between them is the diameter of the tip. They are the ones that are used most often, and therefore they also fail more often.

On the Internet you can find a lot of materials about this wonderful soldering iron. But I will also share my experience in assembling a kit for a soldering station using Hakko T12 tips. And in the next article we will talk about assembling a soldering station with a hair dryer. So, the set comes in the following configuration:

2. The controller itself, a connector for connecting a soldering iron, an LED, a handle for an encoder and two displacement sensors (they are placed in the handle and bring the soldering iron out of sleep mode when removing the soldering iron from the stand, you generally need one, but they sent it with a spare).

3. Cable (in elastic insulation).

4. Handle for installing the tip.

5. Wires and heat shrink (these wires are needed if you plan to install a connector for connecting a soldering iron not on the board, but to take it out).

6. Solder and rosin (to assemble the kit, the seller carefully included some solder and a box of rosin).

Handle assembly

Let's start by assembling the handle for the Hakko T12 soldering iron. She puts it together simply. We install a round textolite washer in the groove and solder it. Soldering areas are provided on one side only. For greater reliability, I stripped the mask on the other side and soldered it there too.

Motion sensor

Next you need to solder the displacement sensor. There are some explanations on it. This sensor is a regular tube with two leads and a metal ball inside. In one position the ball closes these two terminals, and in the other it opens. Connect it to the multimeter in continuity mode and turn first one lead down and then the other. Mark the pin in the downward direction that the sensor is triggered. Now, if in your stand the soldering iron is positioned with the tip down, then this pin needs to be soldered to 2, but if the tip is up, then this pin should be soldered to 1.

Wiring

From the board side we see -,-,SW,+,E. You need to solder like this:

Board Handle
— —
- A
SW B
+ +
E earth

On the side of the handle, the cable is fixed with ties.

DO NOT FORGET TO PLACE THE HANDLE AND CONNECTOR COVER ON THE CABLE BEFORE WIRING!!!

The final assembly of the handle consists of installing the tip and fixing elements.

Board assembly

Now as for assembling the board. Actually, here you just need to solder the LED and the soldering iron socket. But! The nut securing it is located on the terminal side, and if you solder it now, then later, when installing it in the case, you will have to desolder it. The installation sequence in the case, if the socket is not on the wires, is as follows: mark, drill holes in the case, screw the socket, then install the board (the connector pins fit into the mating holes of the board), screw the encoder, and solder the connector. In this case, the calibration resistor will remain covered by the panel. To avoid this, you can make a hole in the panel opposite it, or you can solder it back, which is what I did (but in this case you will have to recalibrate the station later).