There are a few light makers that produce QTC flashlights:
Myself I love QTC, it’s extremely simple and works great. I like this from-firefly-to-turbo adjustment better than any non-e-switch UI. And e-switches come with a few issues of their own, especially if one wants a really small light.
Thanks guys. Cool stuff indeed. It’s the first time I’ve seen/heard of it. I can certainly see the appeal of it, at least for lights using batteries that don’t have over-discharge issues.
I was interested so a little more googling shows that “Velostat pressure sensitive conductive sheet” is available from many places such as Tinkersphere $3.99 for 12” x 12” piece. Same stuff available directly from Adafruit, Digikey or Amazon for slightly more. Same properties as QTC???
As I remember from Match the only hitch in using this was getting it to stay at one setting. Need some kind of detent to hold the pressure steady.
Great, now you’ve got me wondering what I can do with Indium Tin Oxide Coated PET Plastic 
It’s only 0.1 mm thick…
Isn’t this possible to make yourself?
I mean like a piece of plastic sponge, soaked with graphite and latex mixture or something?
(i guess i should try that myself ?)
It is difficult enough to get the factory stuff working properly.
So, i guess that’s a no then…
Not at all, you might make something revolutionary, but, more likely, just get a sore head trying
I’ve played around with QTC a fair bit and never got it performing 100% to my liking but it can be useful for smaller builds. I might have another go.
Yeah I cant see how the velostat sheet would work for us being so thin, not compressible?
Didn’t look into it.
I tried some QTC and then gave it away because afaict it only works in single mode lights that are battery crushers (no spring above or below the battery).
I do not own any battery crusher lights…
All my lights have a spring, so the QTC would not work.
Graphite powder would seem like the suitable conducting material though.
I’ll pick up a flask at the hard wear store, see what i can do with it.
Good point.
I would like to try it in my Astrolux M01. (10180 keychain light)
No springs and the minus goes via the threads.
I’ve tried qtc before. I prefer the reliability and feel of infinitely variable control rings but those lights are bigger than qtc lights. I would like to try making a non-battery crush qtc host one day, just for the challenge of it 
I did that with a cooyoo 10180 light.
Separate battery compartment, the head twisted to compress the QTC pill onto a fixed stationary contact not the cell itself.
And did it work?
(i think all those keychain USB charged 10180 lights are the same inside)
I wouldn’t have mentioned it otherwise
Yeah, I mean the light was stripped & heavily modified, just remembered it with pinks comment.
A slightly better way to implement QTC.
So you could have a sprung cell compartment and just the head or tail unit doing the variable thing without crushing the cell.
Found an old pic.
not for me
I tried it with a stock 10180 light
they have a 2 mode switch in the head, that is based on a domed metal disc that gets compressed to access the 2nd mode.
That defeated the QTC, which I wanted to use to get a moonlight mode… Instead the QTC would trigger the high mode. iow, the QTC needed more pressure to work, than the 2 mode switch, which is based on a springy piece of metal that would move with less pressure than the QTC needed…
waste of time
That is not to say that a heavily modified light could not be made… but the QTC definitely did not work for my intended purpose with a 10180 light… They come in many brands, they all work the same 2 mode spring switch…
I also tried it in a Fenix E01 and a Maratac, again hoping to create a sublument mode… Total Fail
Yeah, i replaced the springy triangular(ish) disc in mine for a tiny strip of metal.
Works much better, because that springy disc couldn’t be soldered properly to the PCB, causing problems…
And so the tiny strip will have to be removed again if i want to try a pressure sensitive resistor in stead.
I think it’s wise to sandwich the pressure sensitive medium between thin brass sheet discs or between the PCB and a thin disc, so it won’t deform or damage.
Also can put the QTC in the tail to avoid torsional stress, some of the better mods I did that way.
Why does it avoid torsional stress?
Because of the friction between battery and tube?