# Viability of QTC -- is it "over" or is there still some way to make it work reliably?



## xevious (Feb 15, 2019)

*Viability of QTC -- is it "over" or is there still some way to make it work reliably?*

QTC (Quantum Tunneling Composite) seemed like a phenomenal "free lunch" opportunity to achieve a ramping brightness control of a flashlight without the complexity of circuitry. PEAK LED Solutions jumped into using QTC quite a bit, but from all I've been reading it hasn't worked out all that well. All kinds of reliability issues. I had seen some DIY QTC flashlight topics from back around 2011, but they went nowhere...

So what's the upshot on QTC for flashlight use? Was there a "roadblock" reached whereby it was deemed as not a practical device for use in flashlights? I had wondered if there might be some inescapable wear factor... the frequent compressing and decompressing of the QTC material can cause deformation, and perhaps degradation. Is there some other consideration that makes it nonviable? Or is there the potential for a different sort of design that might be able to leverage QTC effectively and reliably for longer periods?


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## archimedes (Feb 15, 2019)

*Re: Viability of QTC -- is it &amp;quot;over&amp;quot; or is there still some way to make it work relia*

Pure compression and decompression is not really the issue, it is that shear forces cause "crumbling" of the substrate sooner or later. Those crumbs then really magnify the jitteriness and "noise" of the resulting output.

Yes, Peak improved their QTC design in succeeding versions, but as a relatively simple electrical "pill" it remains limited in smoothness of response.

There was at least one much more sophisticated (and costly) design modded here on CPF, but I don't recall it progressing to completion and full production, beyond prototypes.

The concept is sound and I think it is a valuable technology, but QTC has been largely dropped, due to lack of both market demand and hobbyist interest :shrug:


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## archimedes (Feb 15, 2019)

*Re: Viability of QTC -- is it "over" or is there still some way to make it work relia*

Here's that link to one of the Fraz Labs threads ...

http://www.candlepowerforums.com/vb...hts-(2nd-run-and-combo-package-now-available)


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## fyrstormer (Feb 15, 2019)

*Re: Viability of QTC -- is it "over" or is there still some way to make it work relia*

I always wondered why nobody tried using the "guts" of a simple carbon-film potentiometer to make a rotary adjustable brightness control, that could be adjusted by turning the head or tail of the flashlight. It wouldn't require compressing anything, so there wouldn't be any thread wear to worry about, and it wouldn't involve any rubber parts that will inevitably oxidize and fail over time.


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## LRJ88 (Feb 16, 2019)

*Re: Viability of QTC -- is it "over" or is there still some way to make it work relia*

My Peak flashlights are working perfectly and dial in to whichever level i want reliably, but i've had them for years now and chances are they're just worn in so well that they don't wiggle out of position etc. too much.


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## fyrstormer (Feb 16, 2019)

*Re: Viability of QTC -- is it "over" or is there still some way to make it work relia*

Alternately you are being more careful when adjusting them than most people are -- not necessarily consciously, but as a matter of habit.

I have a couple QTC Peaks. They're okay, but the lowest settings are incredibly difficult to reach reliably -- it's way too easy to overshoot. I removed the QTC material from one of them and soldered the two halves of the pill together and reinstalled it, using it as a single-mode light. It's much more predictable that way.


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## xevious (Feb 17, 2019)

*Re: Viability of QTC -- is it "over" or is there still some way to make it work relia*



archimedes said:


> Here's that link to one of the Fraz Labs threads ...
> 
> http://www.candlepowerforums.com/vb...hts-(2nd-run-and-combo-package-now-available)


Thanks for your replies, *archimedes*. :twothumbs I think I have a good understanding of it now. Maybe one day if some other composition can be developed that will resist the shearing forces and crumbling, it could actually work.


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## archimedes (Feb 17, 2019)

*Re: Viability of QTC -- is it "over" or is there still some way to make it work relia*



xevious said:


> Thanks for your replies, *archimedes*. :twothumbs I think I have a good understanding of it now. Maybe one day if some other composition can be developed that will resist the shearing forces and crumbling, it could actually work.



You are welcome. It is a very interesting technology, for sure, but does have its quirks.


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## id30209 (Feb 17, 2019)

*Re: Viability of QTC -- is it "over" or is there still some way to make it work relia*

Dang...just read this thread as i got my TheFraz 3rd run...
I like this simplicity, over numerous mods and offers these days.
At the end of the day i just need something simple as QTC. The only thing is bothers me is aluminium housing which is gauged by QTC so brightness transition isn’t smooth anymore. At least pill is still OK so at this time i need to find some thin and hard washer to use over Al body contact lip.


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## xevious (Feb 17, 2019)

*Re: Viability of QTC -- is it "over" or is there still some way to make it work relia*



fyrstormer said:


> I always wondered why nobody tried using the "guts" of a simple carbon-film potentiometer to make a rotary adjustable brightness control, that could be adjusted by turning the head or tail of the flashlight. It wouldn't require compressing anything, so there wouldn't be any thread wear to worry about, and it wouldn't involve any rubber parts that will inevitably oxidize and fail over time.


Sounds interesting -- the current designs aren't as concerned about miniaturization, but I wonder if a different design could be achieved that would be workable in a flashlight.


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## Hoop (Feb 17, 2019)

*Re: Viability of QTC -- is it "over" or is there still some way to make it work relia*

Very fine threads should help with the brightness accuracy. The mechanism can also be designed to transition into true direct drive at maximum crush level. I've designed and modeled a 10mm qtc non-battery-crush pill in 2016. NBC QTC pills can be made very small.

It has been done more times than I had previously thought, as pointed out to me by Calvin at IS: Veleno Quantum, Jetbeam Mini-1, Cooyoo Quantum, Mecarmy Illuminex, Maratac Peanut, and more.


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## fyrstormer (Feb 17, 2019)

*Re: Viability of QTC -- is it "over" or is there still some way to make it work relia*

The Jetbeam Mini-1 uses a metal "bottle cap" switch (I don't know the correct name) that provides two stages of brightness: The low stage engages when the metal "bottle cap" switch comes in contact with a brass pin connected to the positive battery terminal, and the high stage engages when that brass pin pushes the "bottle cap" switch against a contact directly beneath it on the driver board. It's basically a different version of the same two-stage switching mechanism used by the Muyshondt Aeon/Nautilus and the McGizmo PD lights.

The problem with threaded compression switches like Peak's QTC, where you have to pinch the hell out of a little chunk of semi-conductive rubber to get full brightness, is not so much making adjustments when increasing the brightness, but when decreasing the brightness. In that case you're fighting friction between two sets of tightly-meshing threads, and that makes it extremely difficult to avoid overshooting the brightness you want. (yes, even with proper lubrication on the threads; I own a couple.) I've gotten the best results from my Eiger Ultra, because the head is much wider than the threads, so my hand has more leverage to make very fine adjustments when loosening the head to lower the brightness. But it's still less precise than, for example, the control rings on my Jetbeams, which don't build up any compressive force at all when making adjustments.


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## wosser (Feb 27, 2019)

*Re: Viability of QTC -- is it "over" or is there still some way to make it work relia*

How about using a load cell instead of fancy materials? The circuitry may be a bit more complex but the principles of operation and environmental susceptibilities are well understood.

You can even tune a load cell in either hardware (more or less metal in shear/bend) or software (ADC limit / average, temperature compensation).


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## TheFraz (May 25, 2019)

*Re: Viability of QTC -- is it "over" or is there still some way to make it work relia*



archimedes said:


> Here's that link to one of the Fraz Labs threads ...
> 
> http://www.candlepowerforums.com/vb...hts-(2nd-run-and-combo-package-now-available)



I've been gone a while, but it is worth it 

We have some very interesting things about to be available.

-Fraz


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## TheFraz (May 25, 2019)

*Re: Viability of QTC -- is it "over" or is there still some way to make it work relia*



id30209 said:


> Dang...just read this thread as i got my TheFraz 3rd run...
> I like this simplicity, over numerous mods and offers these days.
> At the end of the day i just need something simple as QTC. The only thing is bothers me is aluminium housing which is gauged by QTC so brightness transition isn’t smooth anymore. At least pill is still OK so at this time i need to find some thin and hard washer to use over Al body contact lip.



The flicker that comes with qtc degrading and other imperfections related to the pressures in a twisty type switch were one of the main things that needed to be addressed. That and the material itself. I've been R-and-D-ing for a couple years since the last model released - I feel confident these issues are addressed.

-Fraz


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## id30209 (May 25, 2019)

*Re: Viability of QTC -- is it "over" or is there still some way to make it work relia*



TheFraz said:


> The flicker that comes with qtc degrading and other imperfections related to the pressures in a twisty type switch were one of the main things that needed to be addressed. That and the material itself. I've been R-and-D-ing for a couple years since the last model released - I feel confident these issues are addressed.
> 
> -Fraz



Wow! The Fraz is here[emoji1690]
Are we about to see new improved design?


Sent from Tapatalk


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## TheFraz (May 25, 2019)

*Re: Viability of QTC -- is it "over" or is there still some way to make it work relia*



id30209 said:


> Wow! The Fraz is here[emoji1690]
> Are we about to see new improved design?
> 
> 
> Sent from Tapatalk



Absolutely! 
Good to be back. New engine design that will accept easily user-replaceable smart materials (of the QTC nature). I will update the original thread soon and make a new thread of the new models. All manufacturing is done in-house now, so it will be small batch at first. Four new models currently in operation - 18650, and 3 26350 models (weird, I know). Including what I think is the current shortest nasty thrower (uses a 26350).

-Fraz


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## id30209 (May 25, 2019)

*Re: Viability of QTC -- is it "over" or is there still some way to make it work relia*

Awesome[emoji106][emoji106]


Sent from Tapatalk


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## TheFraz (May 25, 2019)

*Re: Viability of QTC -- is it "over" or is there still some way to make it work relia*



id30209 said:


> Awesome[emoji106][emoji106]
> 
> 
> Sent from Tapatalk



Working on getting a better photo hosting service. Here is a pic of the thrower and 18650 on Instagram: https://www.instagram.com/p/BxLeaavgyfq/

I'll have more and better info soon.

-Fraz


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## id30209 (May 25, 2019)

*Re: Viability of QTC -- is it "over" or is there still some way to make it work relia*

Great design and biggest update in this thread!
Didn’t expect this is going to be in the final stage TBH therefore it makes even more interesting! 
IN for each!!!


Sent from Tapatalk


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## TheFraz (May 25, 2019)

*Re: Viability of QTC -- is it "over" or is there still some way to make it work relia*



id30209 said:


> Great design and biggest update in this thread!
> Didn’t expect this is going to be in the final stage TBH therefore it makes even more interesting!
> IN for each!!!
> 
> ...



Thx! I've learned my lesson . I didn't want to post anything new until everything was ready to go.

-Fraz


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## bla2000 (May 25, 2019)

*Re: Viability of QTC -- is it "over" or is there still some way to make it work relia*

I'm interested in the 18650 design. Welcome back.


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## TheFraz (May 26, 2019)

*Re: Viability of QTC -- is it "over" or is there still some way to make it work relia*



bla2000 said:


> I'm interested in the 18650 design. Welcome back.



Thanks for the interest bla! Here is a link to a video for ya @bla2000 ...Instagram again

https://www.instagram.com/p/Bx6i6NVA3vX/

This is the tech we are using now. Easily user-replaceable QTC or other smart material that works the same way....much like the flint in a lighter. The interesting thing is, we now have a system that keeps the QTC viable long after it has fallen apart and would otherwise be flickery(sp). The full details on our new design will be available soon on these threads and other media. Thanks for your interest!

-Fraz


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## id30209 (May 26, 2019)

*Re: Viability of QTC -- is it "over" or is there still some way to make it work relia*

That’s what i need it in my old “Z”!
This 26350 looks even better then i thought.
Can it be ordered, extra QTC with purchase of new batch or we have to source these pills?


Sent from Tapatalk


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## TheFraz (May 26, 2019)

*Re: Viability of QTC -- is it "over" or is there still some way to make it work relia*



id30209 said:


> That’s what i need it in my old “Z”!
> This 26350 looks even better then i thought.
> Can it be ordered, extra QTC with purchase of new batch or we have to source these pills?
> 
> ...




Thanks id! Yes, the replaceability is paramount in developing one of these lights as it were. But I've always wanted to develop it to the point of the material being broken down to near dust and still working. The light will still work if it's broken down beyond dust...as was in my original design. But now it is user replaceable, and there are more options available of 'smart materials' that are basically pressure sensitive variable resistors. All of these are usable in this engine. And within the quickness of replacement that was shown in that video...hopefully much faster than a zippo lighter. The thing about the 26350 you will like is it's insane throw for a compact size. I loooooved the d-mini. Ill show that soon. 

-Fraz


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## bla2000 (May 26, 2019)

*Re: Viability of QTC -- is it "over" or is there still some way to make it work relia*

Thanks for the vid. It looks like it works fine with the degraded qtc.


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## xevious (May 26, 2019)

*Re: Viability of QTC -- is it "over" or is there still some way to make it work relia*



TheFraz said:


> Thanks id! Yes, the replaceability is paramount in developing one of these lights as it were. But I've always wanted to develop it to the point of the material being broken down to near dust and still working. The light will still work if it's broken down beyond dust...as was in my original design. But now it is user replaceable, and there are more options available of 'smart materials' that are basically pressure sensitive variable resistors. All of these are usable in this engine. And within the quickness of replacement that was shown in that video...hopefully much faster than a zippo lighter. The thing about the 26350 you will like is it's insane throw for a compact size. I loooooved the d-mini. Ill show that soon.
> 
> -Fraz


Sounds fascinating -- thanks for updating with this info, Fraz!


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## JimIslander (May 26, 2019)

*Re: Viability of QTC -- is it "over" or is there still some way to make it work relia*



fyrstormer said:


> I always wondered why nobody tried using the "guts" of a simple carbon-film potentiometer to make a rotary adjustable brightness control, that could be adjusted by turning the head or tail of the flashlight. It wouldn't require compressing anything, so there wouldn't be any thread wear to worry about, and it wouldn't involve any rubber parts that will inevitably oxidize and fail over time.



Voltage dividers are great for applications where you need to vary the voltage, but very inefficient if you want to pass any appreciable current through them. Unless you used the pot to control a power chip (maybe that is what you meant), it would kill your battery pretty fast (and get hot).


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## gunga (May 29, 2019)

*Re: Viability of QTC -- is it "over" or is there still some way to make it work relia*

Interested. I gave up years ago. Looking forward to this.


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## gunga (Jun 27, 2019)

*Re: Viability of QTC -- is it "over" or is there still some way to make it work relia*

And a month later nothing is happening again. 🤔


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## id30209 (Jun 27, 2019)

*Re: Viability of QTC -- is it "over" or is there still some way to make it work relia*

Just about to post similar... lol


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## Obijuan Kenobe (Jun 28, 2019)

*Re: Viability of QTC -- is it "over" or is there still some way to make it work relia*

Love the phat thrower. I was in on the first idea thread...and still listening here.

obi


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## TheFraz (Jun 28, 2019)

*Re: Viability of QTC -- is it "over" or is there still some way to make it work relia*



Obijuan Kenobe said:


> Love the phat thrower. I was in on the first idea thread...and still listening here.
> 
> obi









This one? Pretty compact too. I've always loved the D-Minis of the world.

Finished my favorite design I've ever made today. I'll make a post about it - don't want to hijack this thread. I'll describe in the thread why it has taken so much time from my last models to these new ones. 

-Fraz


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## neutralwhite (Jan 13, 2021)

*Re: Viability of QTC -- is it &amp;quot;over&amp;quot; or is there still some way to make it*

thanks and would this be the case still considering Fraz Labs bringing QTC back in 2021? 
the substrate still an issue ? 



archimedes said:


> Pure compression and decompression is not really the issue, it is that shear forces cause "crumbling" of the substrate sooner or later. Those crumbs then really magnify the jitteriness and "noise" of the resulting output.
> 
> Yes, Peak improved their QTC design in succeeding versions, but as a relatively simple electrical "pill" it remains limited in smoothness of response.
> 
> ...


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## TheFraz (Jan 13, 2021)

*Re: Viability of QTC -- is it &amp;quot;over&amp;quot; or is there still some way to make it*



neutralwhite said:


> thanks and would this be the case still considering Fraz Labs bringing QTC back in 2021?
> the substrate still an issue ?



Not at all - the qtc experiences no shear at all, it's just straight on compression. Compression fine-tuning has been one of the goals of the last year (the piston has always protected from over-compression which can deform the pill but it is a difficult process to find the perfect 'spot'), and that is pretty tuned as well. With the newer engines you can even put in crumbs or odd-cut pieces and get decent ramping.

Now we have more ideas for qtc (and other smart materials as there are others) longevity.


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