Build Yourself – Hakko T12 Compatible Soldering Iron Station

One of the fundamental skill needed as electronics enthusiast is that of soldering. For this purpose, you need a common soldering iron that typically has a power rating of 20-30 watts or so, which is fine for most work. But if your interest in electronics is really serious, sooner or later you will need a temperature-controlled soldering iron

The common soldering irons don’t have any form of temperature regulation. This kind of iron has no thermostat, so it’s always on. That’s why it’s hot to the touch, and also why it can’t heat up things very well: if it had any power it would burn up because it is turned on all the time! The tip stays hotter than it needs to be (so it doesn’t cool down too quickly when you do apply solder), so the solder that is on the tip oxidizes quickly. This makes for poor thermal conductivity which makes soldering hard. And when you do apply solder, the tip cools down quickly, and may not have the heat capacity to get a circuit board hot enough to make a good solder joint unless you hold it there for a long time.

A temperature-controlled iron has a thermostat which switches off the heater when the selected temperature is reached. This means it can have a more powerful heating element, so it heats things up faster. When the iron is unused, the element is switched on just enough to maintain the set temperature and does not overheat, maintaining a better tip surface. Plus you can set the temperature to match the kind of solder you are using (hotter for lead-free), turn it down to solder delicate or heat-sensitive parts, or turn it up to work on large or heat-conductive terminals. Beware though, that some irons may look temperature-controlled when they are only “adjustable” — they have a control knob that merely adjusts the power to the element. Since they are open-loop the temperature is not really controlled at all.

Definitely, this sophisticated functionality will cost you more. Although it is completely worth it, there are cheaper Chinese clones of Hakko T-12 soldering station that you can buy on eBay or Aliexpress. You can buy this soldering iron with an enclosure or without, with or without a PSU, as a kit or as an assembled unit. The nice things about it are that

  • quick heating,
  • auto sleeping,
  • take up the iron handle to wake the controller up,
  • get higher temperature by pressing the encoder, and
  • the T-12 tip seems genuine and has a variety of Hakko T12 replacement tips for it.

This kit is fairly popular, here is an introductory link.

Assembling the kit

I bought just the kit without the enclosure nor the PSU. I laser cut the enclosure myself using 3mm MDF and for the PSU I use an idle laptop adaptor found on my desk. Overall it costs me less than $20 for a temperature-controlled iron that has the above-mentioned features.

The kit comes with the following items:

The first step to do is to solder the red LED on to the main control board. The LED has two leads, one longer than the other, the longer lead is the positive (also known as the anode) lead.

The next step is to get the 5 pins male “aviation” connector soldered to the left hand of the board after plug it through the enclosure front panel. Beware the position of the pins!, pin labeled E (Earth/Gnd) should correspond to pin 1 of the female connector below.

Incorrect soldering of this 5 pins male connector will cause the pin numbering and cable coloring convention described in this tutorial will be no longer valid. To correct it, you need to make your own connection convention. It should be easier than desoldering and reposition the 5 pins male connector.

Now take the female “aviation” connector and the silicone cable. Please notice the pins numbering of the female connector as shown below.

Cut back about 25 mm of the outer sleeving from one end of the cable. Roughly determine the length that the wires need to be when the socket is screwed together. Cut and tin the ends of the wires and also the socket pins then solder the wires to the pins. It is important at this step to note down which wire color is soldered to which pin number. It will be needed later when soldering the other end of the wires to the PCB stent. I’m using the following convention:

  • Pin 1 to  Green
  • Pin 2 to  Red
  • Pin 3 to White
  • Pin 4 to Blue
  • Pin 5 to Black

Slide the transparent sleeve over the connections and screw the socket into the housing. Tighten the small screws of the cable clamp.

Solder the vibration switch onto the PCB stent with the “golden” colored lead uppermost i.e. nearest the silicone cable.

Now slide the other end of the cable through the handle. Strip and prepare the wires as before, notice label of the holes in the PCB stent where the wires will be soldered to. Using my convention above:

  1. Green to GND
  2. Red to +
  3. White to B
  4. Blue to A
  5. Black to –

Fix the cable to the PCB stent with the supplied tie wrap.

Slide the PCB stent into the handle and locate in the grooves. Screw on the top of the handle and slide the element and tip inside. Finally, slide over the ferrule and secure with the collet.

Testing the assembled unit.

You need to provide a power supply unit whose specification falls within the range shown in the table below.  The higher the voltage of the power supply you use, the higher the power the iron can produce. I use a 16-volt laptop adapter which will power the iron up to 32 watts.

Connect your power supply to the 3 pin connector on the control board using the provided plug cable. The negative (-) and earth (E or GND) from the controller are connected together to the negative lead of the power supply.

The first test is to power the controller on without the soldering iron connected. The LED temperature display should show 000 then changes to 500 after 0.5 sec. The heating red LED will be off. If all well then connects the iron and perform the final test.

Switch on and rotate the adjustment knob to the desired temperature, in my case 200 degrees. The heating red LED will be flashing. The LED temperature display should show 000 then changes to 200 after 0.5 sec. The T12 tip begins heating and will reach the set temperature in around 12 seconds.

Laser cut enclosure template

With the attached template you can laser cut the enclosure yourself if you have a laser cutter or through a laser cutting service. The template is designed for 3mm material such as MDF, triplex or acrylic and available in Coreldraw 12 and postscript format.