I am going to do an occasional commentary on new ideas in technology and designs. First up, QTC.
One of the new technologies filtering its way down from cutting edge custom lights is something called Quantum Tunneling Composite or QTC. It is a really interesting material that, when used in flashlights results in a very simple, durable, easy to use infinite variable output light.
Here is the wikipedia article on QTC. The idea is pretty simple. Imagine a car tire. Now imagine that the car tire is heated up so that you can sprinkle in shavings of metal, lots and lots of shavings, not enough for all of them to be touching, but a lot. Now imagine that tire goes back to its normal temperature and the metal shavings are set in place, "frozen," suspended in the rubber tire. The rubber gives a bit, so if you push hard enough you can make the metal shavings touch. And when they touch you can use these temporarily connected shavings to send an electrical current from one side of the tire to the other. Without pressure there is no touching and without touching there is no transmission of current. With pressure, you have a circuit or part of circuit. Obviously the materials and manufacturing are a bit more sophisticated than this, but the example conveys the general idea.
The cool thing is that because of quantum mechanical principles a linear increase in pressure causes an exponential increase in conductivity. With no pressure the QTC material is an almost perfect insulator. With a lot of pressure is an almost perfect conductor. Awesome, right? But what does this have to do with flashlights?
It allows for a very simple variable brightness control. With a little current the LED burns a little. With a lot it burns a lot. Thus a small amount of pressure, say like the tightening of a twisty switch on a flashlight, allows for a marked increase in brightness. Stop anywhere during the 360 degree twist and you get a different amount of conductivity and thus a different amount of light. It is not only highly controllable, it also allows for a super simple UI. On=twist, brighter=twist more. A review of my preferences in UIs can be found here and QTC would fit in at the upper end of preferred UIs.
Until QTC, infinite variable brightness flashlights relied on complex mechanical or electrical regulating devices, like those seen on the HDS Rotary, the Sunway V-series lights, and the Surefire Titan T1 and T1A. But starting with Steve Ku's beautiful jewel of a light, the 38DD (think what you want, just be careful when typing it into Google at work, I recommend "38DD FLASHLIGHT"), QTC was available. The 38DD was a very limited release and $190 for a keychain light is a bit much for most people, but Steve proved that the technology was viable on a consumer flashlight.
As of this July though, QTC has gone mainstream. Peak flashlights, a semi custom maker, now has QTC on its two most popular models--the Logan (a single cell 123A) and the Eiger (a single cell AAA). Both lights have brass, HA aluminum, and stainless steel body tubes and a variety of other battery options, but now both also have infinite variable brightness in the form of QTC. And here is the cool thing--they are no more expensive than a regular flashlight. The HA aluminum Logan can be had for $69.95. Peak has the worst website in the world (the link for the Logan's price is, in fact, to a distributor, as their main site does not get updated and hasn't been since like 2009), but their lights are very high quality, small batch runs and now with QTC they are at the head of the pack in terms of technology.
I can only see this tech spreading. It is very effective. It is super cheap. And, if sandwiched between metal plates, like it is on the Peak lights, it is very durable. The sweep up and down in intensity is not as smooth as say that of a well made HDS Rotary or the Titan, but it is still pretty good. Here is a good YouTube demonstration.
Imagine what Surefire could do with this tech? A cheaper, smaller Titan sounds really friggin good to me. What about a more mass market 38DD? And there is rumor that the scourge of the flashlight world (not really, but still) Lummi has a light in testing stages that uses QTC.
Be on the look out, QTC is coming to gear near you.