Variable soldering iron heater construction and operation questions

Collapse
X
 
  • Time
  • Show
Clear All
new posts
  • caphair
    Badcaps Legend
    • Nov 2011
    • 1249

    #1

    Variable soldering iron heater construction and operation questions

    I have a variable soldering iron that uses 24v 50w heating elements.

    I'm wondering how the temperature is controlled, is the 24vac constant and pulsed per setting or is it like a light dimmer where it operates in any range up to 24vac?

    Also the heating element itself, I noticed one end has another wire twisted to it which is then spot welded to the wire that is soldered on the PCB of the iron. Curious why only one end is twisted with another wire and not both sides?
    Attached Files
  • capwizard
    Badcaps Legend
    • Jun 2016
    • 1991
    • USA

    #2
    Re: Variable soldering iron heater construction and operation questions

    A good solder station's temperature is control by PID (proportional–integral–derivative) controller.

    Cheap one uses light dimming circuit that has no feedback so the temperature of the soldering iron tip is not precision.

    That wires are thermocouple which is two different kind of metal wires welded together.
    Attached Files
    Last edited by capwizard; 01-30-2019, 12:15 PM.

    Comment

    • caphair
      Badcaps Legend
      • Nov 2011
      • 1249

      #3
      Re: Variable soldering iron heater construction and operation questions

      The wires are coming from the heater element not the thermocouple. The thermocouple wires are the red and blue

      Comment

      • capwizard
        Badcaps Legend
        • Jun 2016
        • 1991
        • USA

        #4
        Re: Variable soldering iron heater construction and operation questions

        I bet you the red and blue wires are heating element. you can distinguish both by using meter test those resistances.

        Thermal copper is almost like a short under one ohm and heating element will be around 6 or 20 ohm.
        Last edited by capwizard; 01-30-2019, 01:59 PM.

        Comment

        • eccerr0r
          Solder Sloth
          • Nov 2012
          • 8675
          • USA

          #5
          Re: Variable soldering iron heater construction and operation questions

          Usually thermocouples aren't wound in a tight spiral like heater elements, but don't know, that solder iron heater looks weird.

          Comment

          • stj
            Great Sage 齊天大聖
            • Dec 2009
            • 30941
            • Albion

            #6
            Re: Variable soldering iron heater construction and operation questions

            interesting picture.

            Comment

            • capwizard
              Badcaps Legend
              • Jun 2016
              • 1991
              • USA

              #7
              Re: Variable soldering iron heater construction and operation questions

              It's not fair, I didn't see it clearly. Because I used my mobile phone at work, I went home and saw it with pc, I found out the heating coil was out side the ceramic tube. WOW....I lost my bet.
              Attached Files

              Comment

              • redwire
                Badcaps Legend
                • Dec 2010
                • 3900
                • Canada

                #8
                Re: Variable soldering iron heater construction and operation questions

                24VAC soldering station controllers use "bang bang" control.

                PID control is not useful because there is a huge delay caused by the thermal resistance from the heating coil to the tip, and the tip has large thermal mass. So the heat transfer is poor (ceramic) and a tip takes a while to heat up.
                There is also error because the thermocouple sort of is in the middle, between heater and tip. None of this is ideal which is why Hakko integrated everything into one cartridge.

                Say, for 50% output or 1/2 heat you pulse the heater on and off every second, compared to using phase-control delaying the TRIAC firing 90°. The time constant for a soldering iron heater+tip is long and it just averages out the same.

                Bang-bang (on/off) control is preferred because the thermocouple signal gets alot of AC hum when the heater is on. It would be worse with phase-control, the noise from the heater pulse can swamp the thermocouple signal. Again, new Hakko stations shut off the heater, sample temperature, and then turn heat back on, to get around this problem.

                This also may be why you see a lop-sided heating coil. The ground side of the heating element can affect noise (hum) the thermocouple picks up, it needs to be closest.

                I see a two-wire tunnel for the thermocouple wires. You can prove it's a thermocouple because (+) lead is magnetic and (-) is not, and pretty much a short circuit. Type J output is only 1.28mV at room temp and 27.4mV at 500°C/932°F.
                Nichrome wire does not solder, so that could explain the spot-welded splices.

                https://cdn.badcaps-static.com/pdfs/...bff0741553.pdf

                Comment

                • caphair
                  Badcaps Legend
                  • Nov 2011
                  • 1249

                  #9
                  Re: Variable soldering iron heater construction and operation questions

                  Yes the outside ceramic tube is removed. And if you notice one end of the heating coil I had another wire twisted around it but the other end doesn’t. That’s what I’m curious about, is there a reason for that?

                  Comment

                  • redwire
                    Badcaps Legend
                    • Dec 2010
                    • 3900
                    • Canada

                    #10
                    Re: Variable soldering iron heater construction and operation questions

                    I can't see the other end, but I think the heater wire is doubled-up for the center run, so it doesn't heat up. You want the outside coil as the heater, not the center run glowing orange hot.
                    It's still odd because there are three wire ends, where is the fourth

                    Comment

                    • capwizard
                      Badcaps Legend
                      • Jun 2016
                      • 1991
                      • USA

                      #11
                      Re: Variable soldering iron heater construction and operation questions

                      Originally posted by redwire

                      24VAC soldering station controllers use "bang bang" control.
                      Thank you for your exquisite explanation.

                      Soldering station controllers, there are two more other methods besides you mentioned, one is OK International SmartHeat soldering irons, another one is brain controled poor-man's soldering iron by me.

                      One day, my friend brought a big black box with a tiny soldering iron. Told me, he paid $1200, that was the SmartHeat soldering iron not even has a temperature display just like my poor-man's soldering iron. Both are simple and powerful.

                      Poorman's soldering iron is the only one in the world could use both AC and DC 24 volt and does bronze brazing job and has self-destructing features if you press more than 20 minutes.


                      Metcal, the original SmartHeat Soldering inventor
                      https://www.youtube.com/watch?time_c...&v=S9Wmqc9O24w

                      Metcal SmartHeat Powered MFR-1110 Soldering and Rework
                      https://www.youtube.com/watch?v=RWU6yT9pb2M

                      ---------------------------------------------------------------
                      OK International Metcal

                      Metcal Smart Heat Provides power on demand in response to the thermal load.

                      SmartHeat soldering irons approach manual soldering in a totally different way: it is the tip temperature that is kept constant and not the power supplied to it, and the power varies automatically. SmartHeat detects the increase in thermal load demanded by the larger heat capacity of a bigger joint and compensates by increasing the power.


                      how SmartHeat really works?
                      http://blog.okinternational.com/metc...rks-a-tutorial
                      Last edited by capwizard; 01-31-2019, 09:18 AM.

                      Comment

                      • Curious.George
                        Badcaps Legend
                        • Nov 2011
                        • 2305
                        • Unknown

                        #12
                        Re: Variable soldering iron heater construction and operation questions

                        Originally posted by redwire
                        PID control is not useful because there is a huge delay caused by the thermal resistance from the heating coil to the tip, and the tip has large thermal mass. So the heat transfer is poor (ceramic) and a tip takes a while to heat up.
                        That's what the D term is for -- "anticipation".

                        Comment

                        • capwizard
                          Badcaps Legend
                          • Jun 2016
                          • 1991
                          • USA

                          #13
                          Re: Variable soldering iron heater construction and operation questions

                          Soldering Iron PID Temperature Controller
                          https://www.google.com/url?sa=t&sour...rzc-m-tn93ZdxS

                          PID temperature controller DIY ArduinoYouTube app
                          https://youtu.be/LXhTFBGgskI
                          Last edited by capwizard; 01-31-2019, 10:11 AM.

                          Comment

                          Related Topics

                          Collapse

                          • kalemaroni
                            Opinions on particular soldering iron tip maintenance product
                            by kalemaroni
                            Has anybody tested this product? Posting this question on a Facebook tech group I'm in got a few responses like "that kind of thing corrodes the tips" and "just using normal solder paste is much better" so I'm not looking for generic responses like that, but rather, does anybody know for certain whether this exact product is good or bad for soldering iron tips?

                            ...
                            04-12-2024, 03:52 AM
                          • tony359
                            Kaiweets USB soldering iron
                            by tony359
                            Hi all,

                            I am testing a USB powered soldering iron. It's made by Kaiweets but I believe it's also sold under other names.

                            As a standard test, I checked whether there was any voltage leak from the tip - that said the thing runs on USB-C power delivery so am I correct that the whole unit is floating and not grounded? If I check, I measure 90V at the tip but I have a feeling that that is not relevant? Maybe caused by that capacitor between primary and secondary inside the PSU? I do not see current flowing at all.

                            In other words, do you think it's expected and...
                            02-06-2024, 12:51 PM
                          • acedogblast
                            Guide to transplant MEC1503 EC chip and EEPROM reprogamming for T14s gen 2 and X13 gen 2
                            by acedogblast
                            This is a guide that I am writing for helping others to replace their MEC1503 EC chip if it breaks (or to get around an inconvenient prompt to the BIOS). This forum has been extremely helpful to me so I would like to contribute to help others. I will tell you right now that this task is very difficult to do. You MUST have experience and tools to do precision micro-soldering, BGA reballing, trace repair, and general laptop repair skills.

                            There are some specialty tools needed to do this task. The replacement MEC1503 chips can be acquired from Aliexpress. Do not buy the bare chips as...
                            11-02-2024, 05:13 PM
                          • edugimeno
                            Vaillant 242 Gas Water heater. Shortcut in board anc compatibility with model 282
                            by edugimeno
                            Hi!!
                            Yesterday I was installing a new Wifi thermostat for my domestic gas water heater model Vaillant 242/2-3, and accidentlly one wire from mains touched one wire from the thermostat output contacts. This shut off the heater so I finished installing the thermostat and then went out to check the heater

                            I found one fuse blown (T2 250V). Replaced it with another equivalent fuse and it blew right away. I measured L-N in mains input and I sometimes got 4K but sometimes, not sure why, I got 100 Ohm...
                            At a certain point, moving stuff around, I put all wires back in place and...
                            03-24-2024, 02:31 PM
                          • datsnow
                            [Baku 702B] Soldering iron not heating up and the temperature doesn't go up
                            by datsnow
                            Hi!

                            I'm owner of a Baku 702B. I do some SMD work with it, and since I have a spare soldering iron that works very well for the little soldering that I do, I hardly use the soldering iron that this station comes with.

                            (To add some info, this station went to RMA some months ago, the hot air gun resistance was changed to a new one.)

                            So, some days I needed to use the soldering iron that comes with the station, but for my surprise, the temperature would not rise. The temperature screen would always show 22/23ºc and no matter what, if I rised or decreased the...
                            06-26-2018, 09:29 AM
                          • Loading...
                          • No more items.
                          Working...