November 25, 2004

Product Review: a ‘Cold’ Soldering Iron

NEW YORK -- If you're looking for a good holiday gift for a tinkerer you can hardly give away anything more inventive than the Cold Heat soldering iron.

It redesigns something that's been virtually unchanged for decades and does so by combining high-school level science and cheap materials.

The idea is this: instead of running electric current through the tip of the iron to heat it up, the Cold Heat iron runs the current between the two prongs of its split tip, and thus through the solder. If you make a good connection, the solder is effectively electrocuted and melts in a second.

When the iron's split tip is removed from the solder, it cools down quickly, becoming safe to touch in a few seconds.

And unlike a regular soldering iron, the Cold Heat contains it's own power source, four AA batteries. No need to plug into a wall outlet.

It's not the first cordless soldering iron - there are butane-powered versions, but these cost twice as much as the $20 Cold Heat, take longer to cool and require butane cartridges.

Now you're thinking "Hmm ... I wonder if the Cold Heat works like a cattle prod too?" No, it doesn't.

Remember high-school physics? A low voltage, like the 6 volts produced by 4 AAs, can give a high current when it runs through something that has low resistance, like solder. High current means high heat.

But 6 volts produces only a low current when it flows through something that has high resistance, like skin. In fact, you'll feel nothing if you touch the tip of the Cold Heat to your skin.

The one caveat to using the iron is that if you touch its two prongs to different leads of a sensitive component like a chip, you could burn out the component.

I tried using the Cold Heat for a small electronics project: removing the plastic foot of a camera flash and replacing it with a stronger metal foot. This involved desoldering four leads and soldering two.

I'd done the same operation, on another flash, with a regular $3 soldering iron a while back. That took me more than an hour and resulted in me melting a small part of the plastic shell of the flash. I'd be the last to say I'm a great solderer.

With the Cold Heat, the operation took half the time. The tip did get quite warm in continuos operation, but I burned neither myself nor the flash.

What I appreciated the most was that the Cold Heat tells you when it's heating: it lights a red diode when the circuit between its prongs is closed, and you'll often see bright little sparks at their tips as well. In short, it's easy to use and safer than a regular ion.

So why hasn't anyone come up with this before? Cold Heat, the company, says the tip is made of Athalite, a "proprietary and patented material" that took time to develop.

However, the patents issued to the inventor, Grigore Axinte, are for a cordless soldering iron with a tip of graphite, a common form of carbon used in, among other things, pencils.

The company won't say if Athalite is a form of graphite, but it does look like inventors who were sucking their pencils wondering "What do I invent next?" should have been paying more attention to what they had in their mouths.


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