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"Cold Heat" Soldering Iron

by Bob Scott

As seen in MAKE 02 Toolbox

Type(s): Hand Tool
Tags: solder cold

http://www.radioshack.com/home/index.jsp
$20 (US, estimated) Buy from amazon.com

Tool photo.

"As Seen on TV!" When shopping for quality electronics tools, that's the logo I look for. I was both intrigued and skeptical when I saw this marker-sized gadget in an electronics catalog, along with a brief description that indicated it soldered, while remaining cool to the touch, using just four
AA batteries.

Of course, I had to take it apart to see what was inside. About what you'd expect for 20 bucks: some simple battery holders, snap-fit parts, etc. But, interestingly enough, it also contained a small circuit board complete with an IC that had obviously been "sterilized" by having its markings sanded off.

Equally interesting was the removable soldering tip. Apparently composed of a hard carbon compound, the tip is forked into two electrically isolated tines. To solder, the two tines are shorted across the joint. This allows a large current to flow across the "short," electrically heating it until it's hot enough to melt solder.

The combination of the mysterious circuit and the unusual tip do manage to slam a lot of current through the junction, as witnessed by the impressive spark you get when a good connection is made. Making that connection is critical to the process, and the iron has a dedicated LED that illuminates to indicate that you've hit the mark.

Does it work? Yeah, kinda. The Cold Heat iron seems best suited for small- to medium-sized connections that are mechanically solid and well supported. The pressure required to achieve and maintain a good electrical contact is considerably more than I was used to. I found myself chasing my victim components around the bench until I learned to lock them down before trying to solder them with the Cold Heat iron.

Bottom line: A good buy at the price and handy for your portable tool kit. Since it uses alkaline cells, it's always ready to go, unlike NiCad-powered irons I've owned, which seemed to alternate between dead-from-self-discharge and dead-from-overcharging with no stops in between. The Cold Heat iron is ready to solder quicker than a gas-powered iron, and it cools down seconds after use. If you need a portable iron, the Cold Heat is worth a look, but I wouldn't think of replacing my bench iron with it.

Radioshack stores and online sources.

Discussion

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Cold Heat = Oxymoronic?
Reply

Couldn't pass up on commenting on the coldheat iron. I purchased a few of these on eBay to carry in toolboxes and such after my boss bought one from a TV advert. I followed the instructions, don't press hard and all that, just wouldn't do it for me. If you heat even a small wire too long or do anything too long, the batteries heat up ('cause you're shorting them out) and you lose capacity. I kept on having to rotate the batteries out for a cooler set to finish a job. I finally decided to get a few of the piezo start butane Weller irons from Lowe's. Much better, better heating and same price. Sorry for the rant.....

Posted by Michael123 on July 26, 2006 at 11:50:31 Pacific Time

eh, generally unimpressed, but cordless convenience
Reply

Summary: I only used this a couple of times, but found it hard to use effectively. But it IS cordless and instantly 'on'.

Granted I only have the rather large standard chisel tip, but found it annoyingly difficult to maintain electrical contact on small parts and wires. I definitely didn't trust that it heated everything sufficiently to make good solder joints, but it did work in a pinch. Several times, tiny bits of solder became wedged between the carbon contacts requiring painstaking removal.

With the electrical current involved, I would be weary to use this on static sensitive or in-circuit components, but it can do the job for quickly tinning thick speaker wires and the like.

Posted by dhammy0110 on July 17, 2006 at 14:26:29 Pacific Time

Works pretty well, chisel tip bad for PC work
Reply

I bought one of these a few months ago and recently used it to teach my son to solder (building a miniPOV2 kit to see it in action). I like the convenience of it and if you get the sharp pointed tip instead of the standard chisel tip, it works pretty well for through-hole PC board work and quick fixes.

My biggest gripe was that the iron was $19.95 and the new tip was $9.95...
Posted by cmpalmer on July 14, 2006 at 15:05:40 Pacific Time