I see this mentioned in 4 or 5 threads, including Match's awesome 3*XML but for the life of me I can't find a thread explaining what it is, or how to use it? I just see some sort of pad, I assume resistive in an inverted metal cup in his maglite.
Just do a search for QTC. There are a number of posts related to it.
Hiya VegasF6! As you've mentioned, the qtc pills are used to control current giving a somewhat infinately variable light output. Not a whole lot of specifics on implamentation have been given yet, because it varies from torch to torch. On top of that, even on the mods I've used them on, I'm not completely satisfied with the results...which is why I haven't gone into too many details yet.
For example, on my mini-match (minimag) mod, it works outstanding, but current mounting leads to premature wear. Then on the 3xXM-L build, wear isn't the issue, but linear control is. When adjusting the head, I don't get repeatable output results....it seems to jump around a wee too much for my taste.
Trust me, when I come up with a solid solution that I'm happy with I'll be more than happy to share it in great detail.
Thanks Match. I sure did love that 3*xml candlestick of yours. (did you come up with a name yet? Makes me think of candlestick bowling :) )
I did at least find Don's sales thread so that gave me a starting point.
Prior to that I really had no idea. So I guess you could say it is a variable resistor, a little like an NTC or something, but the amount of resistance is controlled via pressure. Very interesing I have never heard of such a thing! I still trying to gather specs like maximum and minimum resistance and power handling capacity and the effects of temperature, etc etc. I will say I wouldn't try and use it on a switching regulator, but on a linear, I suppose so.
QTC pills are basically pressure-sensitive variable resistors, that don't work like a traditional resistor. Based on pressure, it will vary from an insulator (10^12 ohms) to a conductor ( < 1 ohm), making it an AWESOME lightswitch (and touch/flex/stress sensors, etc, but those don't matter)
As it's basically just silicone rubber with microscopic metal particles in it, it should be ridiculously cheap to mass produce. The closer the metal particles get together, the greater the odds that an electron can tunnel through the surrounding insulator. The number of 'pathways' through the material increases as the material is compressed, lowering the effective resistance.
Since the jumps through the insulating silicone are due to quantum effects, the electrons themselves only see the silicone if they can't make the next jump. To them, they're always sitting happily in a metallic conductor and then "huh?", they've jumped to another metallic conductor. The best part is that with the electrons always in the metal, they don't waste energy causing resistive heating.
If you want to know more, check out:
Are you from Vegas?
Foy
Foy, you seem to have won the random spam prize "SPAM Level: -1" :P
Yep. And I drive an F6 :)
Well, I live in Vegas but I don't drive an F6.
IdriveabeatalltohellZ28Foy