Howstuffworks "How Cold Heat Works"
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How Cold Heat™ Works by Tracy V. Wilson
As an invention, Cold Heat seems to have everything. At first glance, it does something old (soldering) in a new, potentially better way (without a hot soldering iron and the risk of burns). It has the "Why didn't someone do this before?" factor. Cold Heat even has a story -- according to the Web site, its inventor, Grigore Axinte, moved to the United States from Romania in 1991 to "pursue the American dream."
This is the Cold Heat tool we took apart for this article.
The basics look pretty amazing. A Cold Heat soldering tool can melt solder almost instantly, and the tip cools off in seconds. In one TV demonstration, a person uses the tool, then puts the tip on an inflated balloon, and the balloon doesn't pop. But reviewers -- professionals and average users -- either love the tool or hate it, and some people question whether it's really "new" at all. We wanted to know exactly how a Cold Heat tool works, so we took one apart. In this article, you'll learn Cold Heat's secrets, as well as what happened when we tried to use ours.
Joints and Irons: Soldering 101
The first question of soldering is, what is solder, anyway? Solders are typically alloys that melt at fairly low temperatures and harden as they cool, making a sturdy connection. Many solders are made of tin and lead
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Since lead carries certain health risks, lots of companies and organizations have researched and developed lead-free solders. The National Institute for Standards and Technology has compiled a database of lead-free solder properties here. With a soldering iron and some solder, you can connect electrical components, repair jewelry and make stained glass. Usually, the soldering iron plugs into the wall and contains a bit that gets hot enough to melt the solder. The hardened solder and the connection it makes are collectively called a joint. Stained glass artists often refer to it as a bead.
Photo courtesy HowStuffWorks Shopper
A traditional soldering iron
Electrical soldering irons usually have a resistance heating unit, similar to what you would find in a hair dryer or a toaster. Electrical current passes through the heating unit, and electrical resistance causes it to get hot. It takes time for the bit to both heat up and cool off using this process. Burns are an obvious risk when using soldering irons, but they can also damage surfaces, equipment bags and the components being soldered. A Cold Heat tool is different. Instead of plugging it in, waiting for it to heat up and waiting for it to cool off again, you just turn it on, touch the solder and go. To a casual observer, this is the amazing thing about Cold Heat. But tools that do the same thing have been around for quite a while. They're called resistance soldering tools, and you can even get plans for making your own online here. A resistance tool uses two probes that can look like rods, pliers or tweezers. These probes pass a current through the material being soldered. The probes and the solder heat up very quickly because of their resistance to the current passing through them. Removing the solder breaks the circuit, and the tips cool off quickly. The Cold Heat tool might look like magic (some prominent explanations for how it works even feature "magic") but electrical resistance should get all the credit. The tool uses the same principles as a resistance soldering tool, but in a significantly less expensive package. We'll look at this in more detail next.
Soldering Tips Soldering is a fundamental skill for anyone who works with electronics. It's a basic skill, but getting the hang of it -- melting the solder without damaging circuitry or other components and
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getting the right amount of solder in the right location -- can be tricky. NASA's Radio Jove project has a set of instructional videos on soldering technique.
Resistance Isn't Futile
Electricity moves more easily through substances with lots of free electrons, like copper, than it does through substances with fewer free electrons, like carbon. In other words, substances like carbon have greater resistance. Moving current through substances with high resistance takes work, and this work can create heat and sometimes light. This is the same principle that makes light bulbs work. A light bulb has a resistive filament that gets hot and bright when current flows through it.
The Cold Heat tool's wires
The heart of a Cold Heat tool is a broken circuit that runs from a few AA batteries to a tip that has two halves. The tip can look like one solid piece, but a dark insulating material keeps the two halves electrically isolated from one another. When you turn the Cold Heat tool on, the switch closes a circuit that also includes a small light. This light lets you know that the tool is on, and it can illuminate a work surface.
A Cold Heat tip. The dark strip down the center is an insulator. Note that one half of the tip has broken.
But even when the tool is on, a parallel circuit -- the one leading to the tip -- is still broken. This circuit remains broken until you put something conductive, like solder, in contact with both halves of the tip. The solder completes the circuit, also allowing current to pass through a second light. Resistance in both the
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solder and the tip produce heat, and the solder melts. Dry skin doesn't conduct enough electricity to effectively complete the circuit, so the tip stays cool when you touch it.
We'll look at the circuitry and the tip in more detail in the next two sections.
A Closer Look: The Circuitry
We've established that the Cold Heat tool has pretty simple circuitry. The circuit that includes the power switch also includes a small light. A parallel circuit stays broken until both halves of the tip come into contact with a conductive material. A small light on this circuit lights up when it's complete, also. The Cold Heat tool also has some electronic components beyond basic wiring. A small circuit board is at the end opposite the tip. This circuit board has two diodes, several resistors and a 14-pin integrated circuit. When both halves of the tip come into contact with solder, the chip routes power from the batteries through that branch of the circuit.
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The Cold Heat tool has a small circuit board next to the battery contacts.
The flip side of the circuit board So, when you turn the Cold Heat tool on, current flows from the negative pole of the batteries through a wire that leads to a small light. From there, it flows to the circuit board and then to the positive battery terminal. As long as solder isn't in contact with both halves of the tool's tip, that's the end of the process. Once you apply solder, the chip routes lots of power through portion of the circuit that includes the tip. The electricity moves:
1. From the circuit board to one half of the tip 2. Through that half of the tip
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Through the solder Through the other half of the tip Back to the circuit board From the circuit board to the positive battery terminal, passing through another small light on the way
Metal contacts connect the wiring to the halves of the tip.
The tip is as important to the tool's abilities as the circuitry. We'll examine the tip, including what it's made of, next.
A Closer Look: The Tip
According to the Cold Heat Web site, the Cold Heat tip is made from a "patented, revolutionary composite material" called Athalite, named for "Accelerated THermal Action." We suspect it's made from graphite (a form of carbon) or a substance primarily composed of graphite. Here's why: z z z z z
It physically resembles graphite. Carbon has 2500 to 7500 times the resistance of copper, so it can heat up quickly when exposed to electrical current. Some resistance soldering systems use graphite for thicker probes. The company has declined to identify the material, but it has said that it is natural and used in blast furnaces and the locomotive industry [Ref]. Coal, which is mostly carbon, fits that description. The Cold Heat tool's patents describe its tip as graphite. The patents also identify the insulator between the tip's halves as mica.
If the tip is really made from a patented compound, another company owns the patent for it. Hyperion Innovations, maker of the Cold Heat tool and owner of the patents describing it, does not own a separate patent for a compound material. In addition, the only patents that list Grigore Axinte as the inventor are the two that cover the Cold Heat tool.
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Solder: burninated. Tip: broken.
Unfortunately, graphite can be brittle. One of the most common complaints in product reviews and message board posts is that the tip breaks during normal use. Unfortunately, using the recommended light pressure on the tip wasn't sufficient to complete a circuit when we tried to use the tool. Just after we successfully completed a circuit and melted some solder, our tip broke.
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Our broken Cold Heat tip.
We have heard that some people love their Cold Heat tools. We suspect that they have the knack for using just the right amount of pressure at just the right angle, completing a circuit without shorting out any electrical components being soldered or breaking the tip. For lots more information about soldering, electronics and related topics, check out the links on the next page.
Lots More Information Related HowStuffWorks Articles z z z z z
How Electricity Works How Hair Dryers Work How Toasters Work How Light Bulbs Work How Wires, Fuses and Connectors Work
More Great Links z z z z
Resistance Soldering Talking Electronics: Soldering Basic Soldering Guide Georgia State University Hyperphysics: Electricity and Magnetism
Sources
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z z
z z z z z z
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ColdHeat.com http://www.coldheat.com/ Cook, John. "Cold Heat Comes up with a Hot New Way to Solder." Seattle Post-Intelligencer, December 16, 2003. http://seattlepi.nwsource.com/business/152624_coldheat16.html Krakow, Gary. "Cold Heat Soldering Iron Runs Hot and Cold." MSNBC, October 8, 2004. http://www.msnbc.msn.com/id/6151688/ Moon, J. "Cold Heat. Or Was It a Banana?" IGN, February 13, 2005. http://gear.ign.com/articles/590/590411p1.html Resistance Soldering http://www.geocities.com/budb3/arts/meth/sldrrst.html Svensson, Peter. "Cold Heat Soldering Iron." Globe and Mail, November 30, 2004. http://www.globetechnology.com/servlet/story/RTGAM.20041130.gtcoldheatnov30/BNStory/TechReviews United States Patent & Trademark Office: Patent applications 20050247692, 20040149713 and 20020047001, patents 6797924 and 6646228 "Worst Soldering Iron Ever." NewTech, Inc, November 2005. http://newtechinc.blogspot.com/2005/11/coldheat-worst-soldering-iron-ever.html
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