Picture of DIY Cold Heat soldering iron
Or, how I learned to love the ohm.
Ohm, .. ohm. get it? its an electrical joke.. see.. never mind.

Yes folks, you too can make your own Cold Heat soldering iron!

Why spend $19.95 of your own hard earned money when you can make your own from the junk you have laying around. As a bonus, the unit you make will most likely be far more powerful than the commercially produced toy and much cheaper to maintain.

I have always been a "why buy it when you could build it" kind of person. I had seen the ads for the Cold Heat product for some time, but never really considered getting one until someone started asking about Christmas gifts (Thanks Matt). I looked up some reviews, and became fascinated in the "how".

We are playing with electricity and heat here. Please take all necessary precautions and be careful. I won't take responsibility for the scorch marks on the cat. Again.

If you're not interested in the science behind all this and just want to get to the meat, skip to step 4.

**NOTE** Many people have had ideas and recommendations (go figure). I'm going to treat this as an open project. I'll be positing improvements and failures at the end or the instructable. Check frame 10 for further developments. Now, back to the story..
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rkrishnan71 month ago

Great Instructable, really enjoyed reading. For the graphite, I wonder if one could cut up old AA,AAA size batteries of the cheapie variety and use the central electrode. Methinks some pyromaniac used it somewhere for a carbon arc furnace. Will probably need to be machined down in dia. to fit.

Joe Byers1 month ago

This is a beautiful instructable. I can't wait to do it.

Biscuitus1 month ago

Dude, that was very funny and informative. If you need cheap graphite, do a search for tool and die or mold making companies. They tend to use sinker EDM (electro discharge machining) and the primary material used for the electrode is....graphite. When the pieces get to be too small to mill into another trode, most shops just chuck it. Ask them nicely and I'm sure they'd give you a bucket full. If not, drop me a message and I'll see what I have around the shop...

Udon1 month ago

Step one: Goto your local scrapyard. Ask the good people where their printers are.

Step two: Goto the same scrapyard a second time, hoping this day they actually had old printers come in.

Step three: Armed with screwdriver, welding gloves, hammer (also known as a Fujianese screwdriver), and a few hours, proceed to bust open old printers and take the motors. You can score a big bagfull on a good day.

Step four: pay for the laughably underpriced motors from said proprietor of said scrapyard.

Step five: Set the stepper motors aside to build a CNC machine or something later. Crack open DC motors and remove the graphite contactors.


Graphite contactors are hard wearing and designed for friction and strength, they conveniently have copper wires attached, and could be very good for this project.

Sun Gear3 years ago
I tried this instructable. I designed and printed a holder for it out of abs palstic. The volt meter checks out and the power supply is functioning correctly, but I have little to no arcing and it barely heats up. Is there a wait time? what am I doing wrong? I'm using grahite that is fairly thick. I also used a 9v battery with a little but more sucess.

It needs to touch both and you need more amps then when its thicker

Dt.Serkan11 months ago

I'll try it ASAP. One idea to supply the high amperage: 40-80C Li-po battery for RC models. 4.2V and a 2A 40C Li-po battery can supply max 80A current and the resistance between the leads should be around 0.5 ohms. Thanks for the presentation.

I would use lead acid, they are much safer, as long you dont need it for hand soldering. (Btw arent lipos drained out fast at that rate?)

schildress46 months ago
could you possibly put a fuse in it to prevent damage to your power supply?

The PSU should have a builtin reversable ntc fuse

ChrisB206 months ago

Most electric heating elements I've seen Do glow. A dull red.

But if it glows like a bulb...

RedstoneM3 months ago

Tip: you can get good graphite from lantern batteries and why 5V? (And must i use solder when i use my 12V battery or would it solder together by melting 2 parts really?)

EisenF4 months ago

Smash any of the following and receive free sheets of mica - toaster, hair dryer, some soldering irons (tube shaped, like brittle cardboard), some curling irons, and heat guns. When in doubt, just smash two... A sledge hammer is great for toasters - a drywall hammer or similar for the rest.

hagar70441 year ago


just to clarify better for a dumb guy, you can add a drawing / diagram of the assembly?

Couple of quick questions:

a) how about using a pair of mechanical pencils for the graphite electrodes? a 2mm mechanical pencil should work pretty well, and the clutch mechanism on some pencils are metal, making it pretty easy to get a good connection to the graphite ('lead'). It'd be pretty easy to insulate the grip, e.g. using rescue tape, liquid latex, etc. There are also mechanical carpenter's pencils, like this one: https://striker1.com/pencil.html

b) is this a similar principle to 'soldering guns'? in which case, would removing the gun's tip and substituting a couple of graphite electrodes work in a similar fashion?

kurshiukas2 years ago
I duno, but using clay for a spacer was my first thought :)
Roshy102 years ago
Thank you so much, I was (as part of another project) trying to get a pc power supply to turn on, after I finally got hold of a small cat I got it working. YAY
agm882 years ago
Kryptonite is real it glows realy cool just google it
Eng_enth2 years ago
Could you use Char-Kole drawing charcoal sticks with a higher voltage to create an iron that will handle large metal pieces?
That is what I am interested in doing.
Sun Gear3 years ago
so it would seem that thickness plays an important role in this. the thinner the better.
donmatos3 years ago
The translation of low quality sometimesconfuses me, and I'm not even sure about the dimensions of the tip, which seem incompatiblewith the pictures of the phases 01.05.10. When in doubt, I continued searching and found another article on this welding system. There are so many experts who attended with manyvaluable information this fabulous tutorial,including the author himself, I feel a little embarrassed for not having added nothing,except to post the link on another article "coldheat" (pardon me if the said link has already been posted in the last 70 comments that have not read) thanks for sharing this precious ideahttp://eletronicos.hsw.uol.com.br/soldador-cold-heat1.htm
Adam Manick3 years ago
Awesome instructable. If you want to make a battery powered iron that uses a traditional heating element, check out my Instructable.
xiro933 years ago
Oh my god thankyou sir. I just finished mine a lol it ago and it works fine. I did it a lil different but I still got the same results still. Once again thank you.
GamerM4 years ago
its more like welding
GamerM4 years ago

First YOu will need soldering gun.
ilpug4 years ago
very well done. funny and informative.
tamurlane64 years ago
just some tips if you are trying this...

1. Pencil lead from a standard No 2 wood pencil fits very nicely into female molex connector pins. Makes tip replacement a snap!

2. after taking apart a wood burner/soldering iron, I noticed that they had wrapped the copper coil around a thin tube of mica. you can use this for the insulation between your contacts.
that big a tube or just one cut rectangle the same thickness as say... a paper?

the tube was a rolled up piece of mica. I unrolled it, cut a few strips and placed them between the female molex pins.
vignesh12304 years ago
With batteries, you could get a cheap 12v drill and take the battery pack out of it. Then get the individual cells and solder a pack in parallel. You get a low voltage but high amperage. I hope.
eric m4 years ago
not exactly useful for electronics then
luky834 years ago
i'm going to try a piece of an old pcb for the dielectric, easy to shape, heat resistant, not sure it's a proper dielectric though
Sky Woulf4 years ago
in face there is a new man made mineral which has great phosforessence(cant spell) which u put under a light for 2 hrs and it glows bright enough to read by for 12 hrs. they call it krypton because it gives off the green glow just like Superman's nemmisiss (again cant spell)!
turbojet4 years ago
If I can have an advice, you should replace the PC power supply with anything else, because it wastes lots of energy (at least ATX does). 10-15 Watts are quite enough for soldering, and since you built a soldering device, the new power supply can be built easily.

You'll need a casing, 230 VAC male connector with a cable, a 230 to 5 volts transformer, 4 diodes (5V 4A) for a graetz-bridge, a Zener connecting the 5V circuit to the ground for your safety, and a - let's say - 4A fuse also for safety. I assume you know how to build a simple power supply out of this. Then you just connect the output of the circuit to the soldering iron through a switch, push-switch, potentiometer, goldfish, goulash, testicles, whatever you want. The power drawn from the network will approximately equal to power used for work, and no power loss on monitoring and control circuitry will be introduced.
this idea is good, i did find some places for improvement for the smaller projects.

what i did was: 
split the two tips into two smaller parts so that i could solder small chip circuits.
it works well but burns the solder leaving it black and non-conductive, im using a Delta Electronics AC adapter for a printer with an output of 30v .83A(too lazy to find a proper adapter) am i using too much current or am i leaving it on there too long?

thanks for the great instructable and any feedback would be great!
I advise you to be very careful with that. Stray current (just like static charge) can damage chips. Although it is relatively rare in practice, it is still not the best idea to risk ruining parts of your application.
turbojet4 years ago
Not bad at all. However it's unfortunatelly useless for practical soldering. When soldering, we do not only want to mount capacitors, wires and such, but we also use lots of semiconductors which aren't resistant to the drawbacks of this technique. Maybe adding a push-switch and connecting the leads with some metal that warms quickly and can hold heat for a few seconds to do the work will do some in our favor. Doesn't it?
andrew1016 years ago
another way is to make the solder into the leads. hear me out connect power to the spool of solder and the other to an alligator clip holding the component o be soldered. the solder will conduct in liquid state to geat the component after its melted :) just use higher gauge solder
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