Hakko t12 soldering station diagram. Soldering station on STC for Hakko T12 tips

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 rate of heating 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.

I bring to your attention a review of a Chinese soldering station based on an STC controller for Hakko T12 type tips.
I’ll tell you right away how it differs from stations on the STM32 controller. The STC does not have a T12 tip library (which is used for individual tip calibration), therefore there is no individual tip calibration and there is no clock. STM32 allows you to remember 3 calibration points for each of its tips.

I apologize right away, for some reason unknown to me, my photos are not attached to the review (perhaps they are too large, only greatly reduced screenshots are attached) + I simply don’t have a lot of things, I will use other people’s photos.

Station selection.
Studying forums and articles led me to the idea that I needed a soldering iron with temperature control.
There are several options for soldering irons that have a temperature regulator built into the handle; they are relatively cheap and quite suitable for amateur purposes.
But the appetite comes with eating))) I really wanted a high-quality soldering iron and, if possible, with digital adjustment.
Everything is simple here - if it’s inexpensive, then it’s either relative quality or temperature control.
Popular in this category.


A more expensive alternative is soldering stations with 900 series tips, for example, manufactured by Lukey.

There are a lot of such stations, including those with hair dryers (it would be convenient for me to use heat-shrinkable tubes), but budget options have one known disadvantage - a small gap between the heating element and the tip, which prevents rapid heat exchange between them. According to many, this gap is needed to compensate for thermal deformations. They say the problem can be easily treated with a wad of foil or a “file,” but somehow I didn’t like it right away.
They also recommended a soldering iron, it does not have such a gap. I didn’t like the fact that I had to buy an additional power supply and “collectively farm” the connector. It is not included in the kit.

In the end, my choice fell on a soldering station with T12 tips. These tips are also devoid of unnecessary gaps, due to the fact that the heating element, thermocouple and the tip itself are sealed into one housing, but they are more popular and their range is much wider.
Similar tips are used by other manufacturers; they have been known since the mid-70s and have proven themselves in operation.
. By the way, they are similar, but sold in other regions.
Several variants of Chinese stations on T12 tips were discovered, as it turned out later even more than I expected. You can buy them in the form of finished products (that’s what I did), or in parts, combining them as you wish. I chose the ready-made option, so the kit cost about the same money, and I didn’t have another soldering iron to assemble the kits.
They differ in the case, power supply, controller and screen, handle. Well, you can choose any sting. In ready-made options, you can usually ask to invest what you want, they say the Chinese do not refuse.

In the kit I also had a yellow sponge for cleaning the tip, rosin and a power cord with grounding. By the way, the tip is securely connected to the ground.

Station management
There is a switch on the back wall of the case. The station is controlled by rotating the encoder and short and long presses on it.
Below are photos of the menu, working screen, Standby and Sleep modes.

A small addition from 04/03/2017.
The old pen let me down a couple of times, the textolite basket was unsoldered. I decided to buy a new one. Reporting...
The FX-9501 pen I ordered arrived. I looked at it, tested it and... put it aside until better (or worse?) times.
I didn't like her.
The photo above shows my old pen (951) and the new one.

First, about the pros. The main reason I bought a new handle was that the old one had a very unreliable textolite basket:

Everything in the new one is much more modern, more beautiful and more reliable:

That's it with the positives. Not many of them, yes...

Minuses.
First, the rubber seal dangles:


Why this is so is completely unclear. But it is clearly thinner than it should be.

Secondly, the inscription is already worn out from the beginning, “antique”:

The tip is a little loose in the handle, but I don’t think it’s critical.

The tip is not secured with a nut, but is simply inserted into the handle. And it fits deeper than the old handle.
It seems like it should be convenient... For this reason, many people buy it. But there are nuances...
In the old tip, the fixing nut is located relatively further from the tip of the tip, in this part the tip is no longer hot and the nut can be unscrewed by hand during operation. I changed the tip without turning off the soldering iron.
This trick will not work with the new pen. The part of the sting that sticks out is already hot.

As a result of the deep seating of the tip, the part of the handle that you hold on becomes noticeably hot during operation. It's not that it burns, but it's unpleasant. This couldn't happen with the old pen.

Well, one more thing, the new pen doesn’t fit well in the holder:

Well, okay, it will be good for a spare pen.

There is one more strange thing about her. If you turn it upside down, the temperature sensor starts to malfunction, and accordingly the temperature “floats”. If you hold it this way longer, the station displays “?20” instead of the cold junction temperature, which in Chinese means “sensor error.”
In the working position (sting down), such an error does not seem to occur.
This probably has something to do with the fact that the green wire is common to the temperature sensor and the ball position sensor. It’s just not clear why there is no such problem with the old handle, although the wiring and sensors are the same.

In conclusion, I will provide several links to comments in other reviews and simply useful links. The information has not been verified by me, please check its accuracy yourself.

A soldering iron is perhaps the most important tool for a radio amateur. The development of electronic components is moving in the direction of increasing miniaturization. Along with the evolution of electronic components, the means of their installation (and disassembly) also evolve. Soldering guns, infrared soldering irons and soldering ovens are widely used in industrial production. But for a radio amateur, the most popular tool remains an ordinary soldering iron. At the same time, every novice radio amateur faces a choice: buy expensive professional equipment or save money. I also went through this path at one time. For a long time I was unable to switch to soldering SMD components due to the lack of the necessary soldering equipment. Since electronics is primarily a hobby for me, I could not afford to buy professional equipment. A compromise was reached by purchasing a soldering iron with temperature control and a replaceable tip. The main drawback of that soldering iron was hidden in the temperature control itself: it was impossible to set the exact temperature, and when heating massive parts, the temperature of the soldering iron could drop significantly.

Conclusion: professional equipment is not affordable for everyone, and inexpensive equipment often does not meet the requirements of modern electronic components. But there is a compromise. As always, the Chinese industry helped us by offering a soldering iron designer for literally 1000-2000 rubles (depending on the configuration).

I received this designer for review as part of . Delivery directly from China took a month. The box was slightly wrinkled in transit, but this is the fault of our mail (information 146%). Everything inside is intact, and thank you for that. Let's go through the contents. The cost of this soldering iron is about 1500 rubles.

Frame

Nice solid body. There are 2 power sockets, one for 220 volts, the other for 12-24 volts. The second socket (12-24 volts) is switching, that is, it is possible to work both from the internal power supply (which is supplied with 220 volts) and from an external source with a voltage of 12-24 volts (for example, from the on-board network of a car). When the plug is connected to socket 12-24, the internal power supply is turned off (of course, if you decide to use this feature). I was pleasantly surprised by the rubber feet included with the case. There is a switch on the front panel. Unfortunately, I received a set with a faulty switch. Initially, I installed it solely for aesthetic purposes (in other words, to plug a hole), later I managed to revive it by dancing with a tambourine. Among the disadvantages of the case, one can also highlight the crooked light filter installed in front of the indicator. To install it, I had to resort to using the black magic of superglue. I got the feeling that the plastic from which the filter was made was cut by hand with scissors. Lastly, the case is actually not that big. If you decide to take the set along with the case, then immediately add the 24-volt power supply, which recently appeared on the product page, to your cart.

Soldering iron control board.

The soldering iron control board does not require assembly; you just need to solder in the LED and the “aviation” connector. The mounting hole in the case allows for 2 options for installing the connector, and the holes on the board leave only one of these two options: with the key facing up.

The assembly order is as follows:

• glue in a light filter
• insert the connector into the front panel with the key facing upwards and tighten the nut on the reverse side
• insert the LED into the board, do not solder it
• install the printed circuit board, the encoder and connector pins must take the places intended for them
• fix the printed circuit board by tightening the encoder nut
• solder the connector, insert the LED into the hole intended for it in the panel and solder it in the same way.

View of the front panel after assembly.

Soldering iron

The soldering iron itself requires more effort to assemble.

The main difficulty in assembling the soldering iron is that the manufacturer used different pin designations on the control board and on the contact board of the soldering iron. However, the seller's page provides the correct wiring diagram.

It was this scheme that I followed when assembling the soldering iron. Recommendations for installing a vibration sensor are also given. Correct me if I'm wrong, but installing the vibration sensor depends on what kind of soldering iron holder you plan to use. If the standby position of the soldering iron is tip down (most modern soldering iron holders assume this is the position of the soldering iron), then the recommendations given are correct. If you are using a homemade stand on which the soldering iron rests with its tip facing up, then the vibration sensor should be turned over. I don’t know why, but there were two vibration sensors in the box (two sensors are also visible in the photographs from the product page). Please note that the wire in the soldering iron handle is secured with a tie. The caring manufacturer of the soldering iron even added one tie to the set.

Among the advantages of the soldering iron itself, it should be noted that the contact board is sent to the buyer already assembled. In early versions of the soldering iron, this board came in parts, and buyers often got confused when assembling it.

The contact board fits tightly into the soldering iron handle and does not dangle.

The soldering iron wire is soft and does not hold its shape. The assembled soldering iron itself is very light. The tip is a copy of Hakko T12, with a built-in thermocouple. Please note the seller's recommendation: prolonged operation at temperatures above 400 degrees reduces the service life of the tip.

The tip is fixed using a special clamping sleeve and nut.

The handle of the soldering iron is “rubber-coated,” and it’s surprising that the rubber pad doesn’t come off (on the old soldering iron it kept slipping off and it was terribly annoying).

After assembling the soldering iron, you need to connect the board to the power supply (how could it be otherwise); for this purpose, there is a connector at the top of the board. The green wire on the connector is for ground. Pay attention to the inscription in the picture above: connect ground and minus to obtain a more stable temperature.

When choosing a power supply, refer to the table on the product page. The second column of the table shows the required minimum calculated values ​​of the power supply current. I note that my soldering iron consumes a maximum of 1.4 Amps when powered by a 12 volt power supply.

In early versions of this soldering iron, when powered with a voltage above 19 volts, it was recommended to unsolder the resistor, which is marked on the board with a frame. I connected the soldering iron to a power supply from a laptop with a voltage of 20 volts, nothing happened to it.

When the power is turned on with the soldering iron disconnected, the value “000” lights up on the display, which immediately changes to “500”. In addition to temperature, additional information is displayed (see symbols in the image below):

• 3 – heating indication (LED);
• 5 – indication of vibration sensor activation (hereinafter, fractional dots on the indicator act as indicators);
• 6 – indication of activation of the short-term temperature increase mode;
• 7 – sleep mode indication.

Regarding calibration of the soldering iron, I can only say one thing: in my case it was not needed. The error of my multimeter with a thermocouple is ±(1.0%+5) at temperatures up to 400°C. That is, at 100°C the error is ±6°C, at 200°C - ±7°C, at 400°C - ±9°C. I checked the compliance with the temperatures installed and measured by the thermocouple in the range from 200 to 400 degrees in increments of 10 degrees; over almost the entire range, the temperature difference did not exceed the error of the multimeter. In cases where the difference exceeded the error, the difference between the set and measured temperatures did not exceed 15°C.

However, it is possible to calibrate the soldering iron. Firstly: there is a trimming resistor on the front side of the soldering iron, marked “CAL”. Secondly: some calibration is provided from the menu. To enter the settings menu, you need to press the encoder and hold it for a couple of seconds; the transition between menu items is also carried out by pressing the encoder. Let's go through the menu items:

• P00: Restore default settings. 0 – do not reset parameters, 1 – reset parameters. At this point, I scroll through values ​​from 0 to 12.

Points P01-P03 relate to temperature calibration. If you do not understand anything about this, then do not change these parameters. If you still change these parameters incorrectly, you can always reset the values ​​to the default values.

• P01: Operational amplifier gain. Range from 200 to 350, step 1, default 230.
• P02: Op amp bias voltage. Range 0 - 250mV, step 2, default value 100.
• P03: Seebeck coefficient of the thermocouple installed in the soldering iron tip µV/℃. Range 30-50, step 1, default value 41. Note that this coefficient is not a constant value, and changes with temperature changes. In the range of 200-400 degrees, the Seebeck coefficient for a K-type thermocouple increases nonlinearly from 40 to ~46 (see graph on page 188 in the book Encyclopedia of Electronic Components. Volume 3 by Ch. Platt).
• P04: Temperature adjustment step. 0.1, 2.5 or 10 degrees. With a value of 0, the temperature change can be blocked. My soldering iron only has 0, 5 and 10 degrees available.
• P05: This parameter sets how quickly the soldering iron will go into sleep mode. Range 0 - 60 minutes, step 1, 0 – disables sleep mode. When entering sleep mode, the soldering iron reduces the temperature to 200℃, and exits sleep mode based on a signal from the vibration sensor, which is located in the handle of the soldering iron, as well as when you press the encoder.
• P06: Automatic shutdown time. Range: 0 - 180 minutes, 0 to 30 step 1, 30 to 180 step 10, 0 disable shutdown function. During automatic shutdown, the temperature of the soldering iron drops to room temperature, and the display shows 000. Exit from such “deep sleep” is carried out according to the conditions established in paragraph P08. The countdown to shutdown begins from the moment the soldering iron enters sleep mode.
• P07: temperature correction. Range 0 -20 degrees in 1 degree increments. To be honest, I didn’t understand this adjustment. According to the machine translation on the product page, this setting should help if the soldering iron incorrectly sets the temperature and always errs by the same value throughout the entire range of adjustable temperatures. But no matter how I tweaked this setting, the data on the displays of the soldering iron and the multimeter always coincided.
• P08: conditions for exiting deep sleep: 0 by turning/pressing the encoder, 1 – by a signal from the vibration sensor and by turning/pressing the encoder.

The soldering iron has a short-term temperature increase mode, which is activated by briefly pressing the encoder. Parameters P09 and P10 are responsible for setting this parameter.

• P09: The parameter sets how many degrees the temperature of the soldering iron will be increased when this mode is activated. Range 20 - 100 degrees, step 10 degrees.
• P10: Temperature rise duration. Range 10 - 250 seconds, 5 second increments.
• P11: This parameter sets the waiting time in the settings menu. After this time, the settings are saved and the soldering iron exits the settings mode (from 4 to 60 seconds). I recommend immediately setting this value higher so that you have time to think when setting up the soldering iron.

The general impressions when using the soldering iron are good; the variety of power supply methods and voltages gives wide possibilities for using the soldering iron in various conditions, including autonomous ones (for example, in a car or simply from a car battery). The low price is another plus for beginners and those simply on a budget. And the variety of replaceable tips allows you to use the soldering iron for a wide range of tasks.

P.S. I also ordered a power supply, but I won’t be able to describe it in this article (the deadline is running out). So everything regarding the power supply will be added later. I also plan, if possible, to order a full set of stings, I’ll also tell you about them later.

P.P.S. I finally got my hands on a 24 volt power supply from the same seller. On the one hand, the power supply pleased me; the soldering iron heats up in a matter of seconds. On the other hand, the power supply does not fit into the case a little, I had to spend the whole evening and a lot of nerves to solve this problem. So...

First you will have to unsolder the 24 volt output connector. It rests on the 220 volt socket. Then you need to bend all the petal contacts on the 220 volt socket to the side, at the very base, by 90 degrees (that is, press them completely to the socket). I placed the power supply itself backwards to front, that is, the 220 volt input on the power supply is located near the “aviation” connector, and the 24 volt output is near the 220 volt socket. Otherwise, there is no way to push the block in at all. The power supply in the case is not secured in any way, but it is pressed on all sides so that it does not move at all. The lid closes with tension, do not break the back panel of the case. I left the option of dual power supply of the soldering iron both through the 220 volt socket through the internal power supply, and through the 12-24 volt switching socket, that is, the autonomy of the soldering iron was preserved. The switch on the front panel cuts off the low voltage, and the power supply remains connected to the network. I would like to install another switch to disconnect the power supply from 220 volts, but there is no room left in the case.

For my birthday I was given a soldering station with replaceable tips HAKKO T12. The kit included three tips, of which I use 2, and only because of poverty. Now we managed to take a set of stings for review - 10 pieces.

What are the benefits of this type of sting? Firstly, they heat up quickly - they heat up to operating temperature in 12-15 seconds.
Secondly, there is a built-in temperature sensor. If you have a normal soldering iron controller and an external temperature meter, it is possible to adjust it within +-7-10 degrees.
Thirdly, they are quick-release. Replacing one tip with another takes 5 seconds.
Fourthly - assortment

Of course, the Chinese brothers make copies, generally of good quality.

Why do you need such a set? Due to the wide range of parts, it is necessary to keep a wide range of tips. There is a universal type - but of different sizes, there is one for soldering massive parts, a needle type - for small SMD parts, a poker - where it is inconvenient to get to the part...

As a result, if you solder different types of parts, you end up with 5-7 tips, which you use often.
But let's get back to the set.

It arrived in this form, packed in a cardboard box and bubble wrap.

The tips have 3 contacts separated by plastic rings.
The length of the tip in the set ranges from 147 to 154 mm - depending on the type.
Each tip has a sticker with the tip type and code.
Tip diameter 5.5 mm
Supply voltage - 24 volts
Power 70 watts
Temperature - up to 400 degrees (up to 450 is possible - but service life is reduced)
Compatible with lead-free solders

The set contains the following tips:
T12-B
T12-BC2
T12-D4
T12-C1
T12-C4
T12-D08
T12-D24
T12-IL
T12-JL02
T12-K

T12-K - convenient for heating several contacts or a massive part, for non-standard ones - welding polyethylene or cutting synthetic fabric.

T12-D08, similar in shape T12-B and T12-IL differ in diameter and sharpening angle

T12-JL02 - used in hard-to-reach places

T12-D4, T12-D24 - Chisel sharpening

T12-BC2,T12-C1,T12-C4 “hoof” - diameter 1, 2 and 4 mm universal tip sharpening

All tips came with a tinned tip.
They solder well, when soldering with ordinary rosin at a temperature above 300, black carbon deposits form on the tip, it is better to use specialized fluxes.
Personally, the kit lacks a “microwave” tip and one with a recess for soldering lead elements.
After a month of use, I did not find any traces of burnout on the sting. The copper one would have to be sharpened twice already.

Nice set for a reasonable price.

The product was provided for writing a review by the store. The review was published in accordance with clause 18 of the Site Rules.

I'm planning to buy +24 Add to favorites I liked the review +13 +31

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.