Pulse soldering iron

I’m always interested in new ways to solder. [SPman] sent in this diy pulse soldering iron. It heats up in 5 seconds on demand, then cools in about 15. The writeup is a bit terse (since it’s translated from Russian), but it would definitely be handy for larger wiring jobs. The transformer is hand wound, and an oscillation driver forms a sort of crude frequency modulation to run the MOSFETS that drive the heating elements. I’d keep it away from delicate electronics unless you’re confidant of the temperature stability. It was designed for 220V, so you’d need to modify the transformer a bit to get similar performance on a 110V circuit.


  1. FlyingAvatar says:

    Isn’t this the same as those “Cold Heat” soldering irons which pretty much suck for real soldering?

  2. deadfool says:

    uuhh id keep it away from pretty much anything but resistors since its not grounded

  3. n3rrd says:

    i’d assume that ‘delicate electronics’ covers anything that is static sensitive…

  4. digidelia says:

    am i the only one that would be afraid to use that thing

    something about holding a homemade 100w transformer in your hand

  5. atrain says:

    Cosmetics: “coating PCB with painting in order to prevent short-circuit (anyway you’ll be holding device in your hands).”

    Don’t worry, if it not go good, your body act as a ground. No trouble! I am actually scared of this guy: one of the few hackers that I would probably avoid meeting in public. (Images of bare wires going into 120v wall sockets come to mind around now)

  6. luigi says:


  7. abbott says:

    interesting concept… no way in hell im using that thing

  8. frodus says:

    Deadfool, all the soldering Irons I’ve worked with aren’t grounded… whats your point? When soldering electronics, you should use a ground strap. Soldering irons are not a source of ground, in fact, can be isolated with transformers.

  9. Spongy says:

    ok, i am honestly scared now, can we remove this or somthing?

    this is so scary.. it makes me think of the early electronics, you know, paper covered lead wire, all sparking and red hot? like in the movies

    i suddenly feel cold


  10. Zengar says:

    Hey, my parents house still has some knob and tube wiring in it, and it hasn’t burned down yet :)

    Yeah, neat idea and I might build one because it looks horifying in a good way, but use it for anything important, heck no.

  11. Bird603568 says:

    its not the temperature that scares me, its that the heating element isn’t grounded. and will is taking about keeping it away because the temp isnt stable.

  12. Bird603568 says:

    awe shit i posted my first post under the wrong name. the 9# post, im referring to the 1st post

  13. Morden says:

    I’m assuming that he either

    A: Forgot to show the ground on schematic

    B: Is an idiot

    All euro outlets are grounded (FOR A GOOD 220v reason), I was also under the impression that most (if not all) european plugs came with the ground connector.

    Heh, I was laughing at all of you freaking out about 120v being ungrounded and not thinking about his 220v connection where he lives.

    But just to freak you out more, when I was REAL young I did pretty much the same thing….and yes, wires will explode in your hands (MYTH CONFIRMED).

  14. sly says:

    don’t even need to use it… just build the thing for freaking out your friends by making your workbench look even more mad scientist… muhahahahahahaha!

  15. Dave says:

    Its really no different than this:


    Which has its uses. Note that anything you make and plug into an electrical outlet will be inherently dangerous without adequate testing. Use common sense.

  16. Bird603568 says:

    dave, ive been told by at a few people not to use the guns because they run current through the tips to heat them up. same thing with the cold heat POS. personally i use this http://www.mpja.com/prodinfo.asp?number=15140+TL which has a grounded tip so there shouldnt be any static and what not.

  17. chupa says:

    best thing i ever did was chuck my radio shack fire starter and get an aoyue soldering station

  18. strider_mt2k says:

    Somebody send this guy a 9.00 soldering kit from Radio Shack before he burns the house down please!

  19. Bird603568 says:

    frodus, the point of a grounded iron is so that it doesnt build up a charge on the iron. the point of a grounded tip isnt so you dont get shocked or you spark on them its so the iron doesnt. and using an anti static band wont do shit for the iron since 99% of irons are plastic (insulator) handles. so unless you are holding it by the shaft its doesnt help the iron

  20. jeicrash says:

    I’ll stick with butane soldering irons for now. But this is cheaper to do than the “DIY” Car kit from yesterday

  21. n00nen0se says:

    In Soviet Russia, iron solders YOU!

  22. HeBD says:

    wow! a dim little light to help you see better.. i wonder what kind of dark little Soviet lab he works in?

    cant say i understand exactly what the chip does in this circet. if 100hz is to high a frequence then he made some mistakes in his memtal arithmatic.

    i dont see what the problem is with the ungrounded tip unless it gets shorted to 220v somehow. realy you could use this for working on live circets.
    also 220v rectified and smoothed looks more like 310v…. i wonder what kind of paint he used? not anything they have in shops in australia!!

    much better that the car building they had yesterday. were was the design download? i wanted to read about how the suspention system was engineered!

  23. atrain says:

    zengar: I trust knob+tube better than what came after it. While the insulation may be paper, at least the wires were usually suspended. I’ve seen houses that were built after knob+tube era was over, but still with paper insulation. Difference is, if loose dry plaster and stuff is at the bottom of the wall where the old burnt wire is lying, better chance of that catching fire then a wire suspended in the air, wrapped in old burnt paper. Both are troublesome, but I think knob+tube has some advantages.

  24. TJhooker says:

    Post apocalyptic electrical engineering at it’s finest.

  25. Wolf says:

    Up next, a matching defibrillator for when you inevitably slip with that thing.

    On a separate note, reminds me of these:


  26. dave says:


    Good point- and you are correct. Any fet input is bound to be extra sensitive to something like this. However, if you need to solder lugs onto #0 or 2/0 jumper cables, then something this thing comes in handy!

  27. DrFel says:

    I don’t see how it’s a hack or any sort of innovation.I had my first weller soldering gun when I was 10 and it still works fine. This might have been a breakthrough in the 1930’s but it’s just a dangerous thing to have around now.

  28. me says:

    I know most of you know this already but.
    Soldering can be used for a lot besides electronics.You can repair glasses and jewelry.I like my soldering gun instead of the iron for anythiung big enough because it heats up so fast.I only use the iron for very small pieces .A propane torch can be used for bigger stuff .You can solder steel with the type of solder they use for car radiators.You have to have the right solder and flux for the right material.For a stronger bond you can move up to brazing ,which requires a hotter gas than propane ,like map gas. For anything stronger you can weld .I’m looking into modifying a 105 amp GM alternator to weld with it. If it works it will save a bunch.

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