Cold Heat soldering iron circuit

[northendtrooper]

1st of all, hi I'm new. I received an A.A.S. in electronics so long ago that I can't remember much... Ok moving on.
I am trying to get 5 amps to my leads to melt solder just like Cold Heat's Soldering Iron.
Here is the circuit that I am trying to replicate. https://science.howstuffworks.com/cold-heat2.htm
I have a couple questions that are bugging me.
Do I really need graphite or can I just use two main metal leads to melt the solder?
How do I get high amperage out of 4 AA batteries?
Can I use basic circuitry (Resistor, Diode, LED, metal leads) and no ICs?
Thanks for any input!

 

[MrAl]

Hi,

No you dont need graphite, you can use metal, but the solder may bridge over it now and then when it is turned off.

Does the 'Cold Heat' soldering iron really only use 5 amps?

A regular soldering gun uses a current transformer, with many turns on the primary and only one turn on the secondary, in order to develop a high current through the tip and the tip is connected in series to that one secondary turn. The thinnest part of the tip is the actual tip and the rest is just the conductors for the tip.

If 5 amps is enough you should be able to get that out of a set of AA alkaline cells or better yet NiCd's. Not sure how long that would last though.

The 'Cold Heat' iron uses the work itself as the tip, the actual 'tip' is just the conductor. In my experience it is absolutely the WORST way to solder something however. It works for small wires but even that leaves a questionable solder joint. A regular iron or gun is best.

If you need fast heat up time a gun works great. Just have to be careful what tip you use and turn the gun off periodically for light work. I wouldnt use this on a circuit board however as it is a little too heavy to control accurately.

 

[4pyros]

No one has said what the IC chip is. In the OP link you can see the number has been scraped off.
I guess its a switching chip.

 

[tcmtech]

Wikipedia has a fairly good description of its design and load of criticism over how it works and wh at all it doesn't work on.

https://en.wikipedia.org/wiki/ColdHeat

That said. If you want to do real resistance based soldering its rather easy to set yourself up with a system and do it. Just take the tip off of your common soldering gun and replace it with two heavy stainless steel or copper electrodes.

I have done it a number of times for doing odd solder joints in heavier materials where the normal tip doesn't conduct it heat away fast enough. In the right applications it does work very well!

Depending on the electrode spacing its possible to be able to solder joints that are far bigger than the normal tip would ever handle.

 

[MrAl]

Hello again,


On that web site they are saying that the main reason that the heat comes about is because the tip itself heats up. That's interesting in itself i guess. But that's not the only way to do it. As we all know, anything with resistance will heat up and do the same thing as proved by replacing the tip with wires. The soldering guns do the same thing, although for the Cold Heat they state that it's mostly the tip itself. No big deal though.

But i think i am starting to see the whole picture here now. The original company came out with a new MATERIAL first, and needed a way to get it to market. Then later they came up with the idea for the "soldering iron". so they were able to use their product in something marketable.

As other web sites note however, the solder joint produced with the Cold Heat is almost always of questionable quality. Usually looks bad although it may still conduct ok for many applications. I cant recommend it however, as other irons even much cheaper ones work much, much better even for a beginner. I know this for a fact because i've watched other people solder with both types.

So does it work at all then? The answer is sometimes, but it's hard to get the tip to heat up sometimes due to work piece contact issues, and the joint is never as good as a regular iron. In it's defense however, i have used it to solder speaker wires. I didnt feel like pulling out the *real* soldering iron when the wires would break off so i would sometimes pull out the Cold Heat *thing*. After some practice i was able to solder the wires, which were always #22 gauge or lighter. Anything too heavy wont heat up, like even some smaller solder lugs.

My suggestion is to buy a regular iron and practice with that. If you are still curious about the Cold Heat thing, borrow one from someone else and see how much you dont like it

I have one sitting on a shelf somewhere that i havent used for many years now. I used it less than 10 times altogether because i dont like the joint it produces. I originally thought it might be good for the car, but most wires in the car are too heavy for the Cold Heat thing and sometimes it is cooler outside so it takes more heat to begin with to heat up a joint. I bought a regular iron that runs on 12vdc and that works great. I also have an inverter that i use with a soldering gun for the real heavy stuff.

If you get a storm and the electric goes out, you can solder small wires with this thing, but that's it. Cant use it for circuit boards period, cant use it for wires over about #22 gauge. So it's only good when there is absolutely no other way to solder in an emergency and then you have to hope it works ok.

So they use a 'chip' in the iron too? If so, that would probably be as a buck converter to get high current at low voltage, but from what the web site says it doesnt sound like they use a converter chip. All the money goes into the production of that specialized tip. Oh yeah, the tip is very fragile too so it can break quite easily.

 

[KeepItSimpleStupid]

OK, resistance soldering.

I knew a guy that was manufacturing train stuff, but was basically "dripping" the solder on his etched pieces. I turned him on the resistance soldering and he was never happier.

American Beauty makes a number of products and two handles in particular, the stripping handle and the pointed handle. I never liked their contacts, and I was extremley happy when I changed to a SS welding rod ground to a canonical point and flattened where they meet.

This is basically a low voltage high current Variac with a foot switch and a hand piece. The SECRET is to make contact to the work first and then hit the foot switch. Remove power and then remove the tool, so it doesn't spark.

The tool is fantastic for soldering pin contacts for cables or soldering Banana Plugs. In fact it's extremely good at stacking banana plugs which are quite massive. You can grip, insert and figure out a way to hold solder remotely or use one hand; grip the banana plug, pass current through it to heat it, solder, release, let it cool. Solder won't stick to the stainless steel.

The Thermo stripper works pretty well for Kynar insulated WW wire and Teflon insulated, but it's still up in the air. You have to choose a stripper carefully.

This is quite difficult to do with a soldering iron.