DIY Cold Heat soldering iron by photozz
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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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Step 1:

Traditional soldering irons use a heated metal tip to melt solder into electrical joints. This concept works great, but it can have some drawbacks. If the iron is too large or powerful, it can easily overheat the joint and destroy the board or components being soldered.

Its also somewhat dangerous to have a chunk of metal sitting around at a flaming 250-400+ degrees. People can burn themselves, and sometimes others, like that one time in my basement. And once in the garage. And maybe a few times in the attic. Not that anyone can prove anything.

The science behind the Cold Heat concept for soldering is not magic. Its not alien technology. Its not even that mysterious. The scientific principles behind the tool have been used in everything from light bulbs to space heaters to building cars. It's all about the resistance.

Viva la resistance!!
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Eng_enth says: Feb 10, 2013. 1:03 PM
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.
vernors says: May 10, 2012. 9:48 AM
so it would seem that thickness plays an important role in this. the thinner the better.
vernors says: May 9, 2012. 6:35 PM
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.
donmatos says: Apr 21, 2012. 7:39 AM
HOW hobbyist, I did NOT YET IF THE GRAFFITI IS IN CONTACT WITH THE COPPER. THANKS FOR SHARING Great idea
donmatos says: Apr 21, 2012. 8:28 PM
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 Manick says: Apr 13, 2012. 6:58 PM
Awesome instructable. If you want to make a battery powered iron that uses a traditional heating element, check out my Instructable.
http://www.instructables.com/id/Make-a-battery-powered-soldering-iron/
xiro93 says: Apr 10, 2012. 5:29 PM
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.
GamerM says: Jul 29, 2011. 1:51 PM
its more like welding
GamerM says: Jul 29, 2011. 1:16 PM
HOW TO MAKE SOLDERING GUN.

First YOu will need soldering gun.
ilpug says: May 16, 2011. 6:12 PM
very well done. funny and informative.
tamurlane6 says: Feb 23, 2011. 4:44 PM
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.
vignesh1230 says: May 4, 2011. 3:34 AM
that big a tube or just one cut rectangle the same thickness as say... a paper?

tamurlane6 says: May 10, 2011. 7:25 PM
the tube was a rolled up piece of mica. I unrolled it, cut a few strips and placed them between the female molex pins.
vignesh1230 says: May 1, 2011. 2:38 AM
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 m says: Apr 25, 2011. 3:40 PM
not exactly useful for electronics then
luky83 says: Apr 21, 2011. 3:49 PM
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 Woulf says: Feb 23, 2011. 2:50 PM
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)!
turbojet says: Feb 14, 2011. 4:40 AM
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.
Amireallyhere says: Jan 30, 2011. 2:42 PM
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!
turbojet says: Feb 14, 2011. 4:07 AM
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.
turbojet says: Feb 14, 2011. 4:01 AM
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?
andrew101 says: Jan 6, 2009. 2:59 PM
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
photozz (author) says: Jan 6, 2009. 8:11 PM
One problem would be that as soon as the solder starts to melt, it "pools" slightly making a larger bubble of solder at the tip. This would provide less resistance, moving the high-resistance point farther up the solder string. It would then melt, breaking the connection and making a mess on your bench. Also, the work itself needs to be marginally hotter than the solder in order for the melted material to flow into the connection. The method your talking about would never get the work as warm as the solder, so it would never flow. You may be able to get away with puting the solder inside a metal tube, but you would have to find a way to keep the solder from sticking to the tube after it melts at the tip.
andrew101 says: Jan 6, 2009. 9:21 PM
yea i guess it wouldnt work so swell. but there must be a way to do something like that
ste5442 says: Feb 3, 2009. 1:38 PM
I know what you mean but its a bad idea!
Some welders use this method but I cannot remember which type?

You can even get soldering robots: http://www.mta.ch/pages/tbrasage_plateformes_tr300.asp

PCBPolice Electronics Forum - we need some users....please!
your_dragon113 says: Feb 6, 2011. 1:40 PM
I think you're thinking about MEG welders that use the spool to carry the charge as well as act as the "Solder"....
ffsta34 says: Feb 13, 2011. 6:40 AM
MIG welders
PJA says: Jan 7, 2009. 12:39 AM
Instead of struggling to cut grooves in hard, brittle dusty stuff, leave the insulating spacer flat and cut the grooves in the copper.
photozz (author) says: Jan 7, 2009. 5:30 AM
That would work as well. I cut the groves in the plex in an effort to get the two leads as close together as I could.
your_dragon113 says: Feb 6, 2011. 1:38 PM
I used single-sided PCB for mine....worked out VERY nicely, and there's always enough of it to be found ;)
cd41 says: Jan 14, 2009. 2:31 PM
I imagine touch this while on would feel too good, especially with its amps coming out like that
photozz (author) says: Jan 15, 2009. 7:26 AM
I have touched the carbon (pencil leads) without incident. The resistance is too high there to shock you. You will feel it if you touch the copper leads though.
your_dragon113 says: Feb 6, 2011. 1:34 PM
I did notice that the longer the lead is...the higher the resistance. Have we found just how long it should be for the best performance?
ste5442 says: Feb 3, 2009. 1:30 PM
photozz (author) says: Feb 6, 2009. 9:05 PM
it's not the volts that getcha.
jam906 says: Feb 8, 2009. 2:58 AM
yeah, iv had 500,000V through me plenty of times, but at far less than 1 amp! this idea is used in electric fences, it hurts but does no damage!
photozz (author) says: Feb 12, 2009. 1:08 PM
If your doing it enough times to warrant the "Plenty of times" tag, you should possibly re-evaluate your leisure activities.
ste5442 says: Feb 7, 2009. 9:38 AM
I think its a combination of both - some welders supply 100's of amps but you can touch the ends with your fingers since its only at a few volts.
With mains voltages (which are inherently dangerous anyhow) you tend to have ELCBs set at around 15mA - this is considered (along with the 240VAC) to be a ~lethal amount apparently?

PCB Police
croslandjr123 says: Dec 7, 2010. 1:28 AM
hey! Thanks heaps for instructable! You have solved one of my problems with PSU's... I tried to turn it on, and nothing happened. No voltage, no fan running. Now you have told me that I have to short the green and black wires on the large connector to get it going. Yay! thanks, man!
Szajba says: Oct 6, 2010. 7:34 AM
monsta!!! :P where is my torch
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