# Playing with QTCs / Fun with QTC / Merged



## PCC (Jan 29, 2011)

Quantum Tunneling Composites, which will only be referred to as QTCs from now on, are small rubber-like pads that conduct electricity, varying its resistance based on how much it is compressed. When static, they provide infinite resistance. As pressure is applied it conducts with lesser and lesser resistance until they reach very little or no resistance. I have not tried measuring this. They can handle up to about 10A of current, though no voltage rating was given for that figure. They come in 3mm X 3mm X 1mm squares that look like small patches of rubber bicycle inner tubing that has been cut into tiny squares.



The Kuku 38DD light uses a QTC to offer infinitely variable brightness levels. I believe there are other lights that use QTCs in them as well.



I really prefer multi-mode lights over single-mode lights because I believe that multi-mode lights are more practical because you can vary the brightness based on the need.



I purchased 100 pieces of QTCs to experiment with and they arrived earlier this past week (please don't PM me asking to sell you any as I fully expect to use all of them and may even need to order more down the road). At first I tried taking the tailcaps off of a few flashlights, putting a QTC on the negative end of the battery, then placing a screwdriver across the bare aluminum of the flashlight contact, pressing down on the QTC to see if I can vary the light's output. For the most part, I was able to vary the output from quite a few of my lights so I know that most of them will work with a QTC mod.



The one light that I have that currently has a QTC in it is a SS Quark Preon ReVO. I removed the rear spring and replaced it with a small piece of aluminum that I turned on my lathe. I reinstalled the rubber retaining ring/spring and dropped a QTC into the body tube, making sure that it sat in the middle, on top of the aluminum piece. I then dropped a battery in the body tube and screwed down the head. What I have now is a light that will come on gently (as opposed to just instantaneously turning on) that I can turn down to moonlight mode or less as needed. I can still turn the light on/off/on to switch modes and I get them, but, I can then slowly loosen the head and the light will dim down. Really cool. It's not perfect as the rubber ring on the negative end of the body and the rubber ring on the head have some torque from the twisting action and this usually means that the light will settle into a brighter or dimmer output after a few seconds, depending on which direction the head was twisted to get to the desired output. Still, it's really nice to be able to use this light in a moonlight mode that makes my Quark 123 Tactical on moonlight mode seem bright. I can get full brightness for whichever mode I'm in by simply tightening the head. The thing is that the circuit board on the light is fighting me when trying to set a low mode and it won't fire the circuit until it's got enough lack of resistance to get about 80% of the power needed to get the normal low mode so it will always start off brighter than I need it to be and needs to be turned down from there. It's been mentioned that the greater stiffness of the QTC setup may eventually lead to a damaged circuit board on the head of my ReVO, and this is duly noted, but, so far so good.



I have a Streamlight BatonLite that I've modified with a Sandwich Shop Mad Max Lite driver and SSC P4 U-bin LED powered by 2 AAA batteries. I removed the tailcap contact assembly and pulled the spring away from the metal washer that makes contact with the end of the body tube to turn on the light. I placed a QTC in between the spring and the washer and reassembled the light. This setup is much easier to set a super low output mode than the ReVO. I can slowly twist the tailcap until the light turns on so dimly that I can barely see any hotspot at all at 3 feet in a completely dark room. From there I can ramp it up to full brightness. I do, occasionally, get a weird quirk where the light will dim before getting brighter, however. I'm not sure why this is. I do worry about rubbing through the QTC because the twisting action is causing the QTC to rub against the end of the body tube.



Other lights that I have tried the QTC on and have acknowledged that it works with them:

Anything direct-drive

Rebel MagLED 2D and 3D

Nite Ize 1-Watt and large dome PR flange drop-ins

Nite Ize 3-LED Mini-Mag drop-in

Sandwich Shop Mad Max Plus and Lite drivers

DatiLED's toroid Joule Thief

ThruNite 3-9V XM-L P60 drop-in

Dereelight SST-50 P60 drop-in pill

SureFire L1 (current version)

SureFire KL4 (120 lumen version)

Quark 123 Tactical

Quark MiNi 123

Quark Preon ReVO



In all cases, I tested by placing the QTC at the tail cap and shorting to the QTC and then applying pressure to the QTC and then observing whether or not I can vary the brightness or not and if it is a smooth transition.



Lights that don't seem to like having the resistance changed at the tailcap:

Solarforce Masterpiece Pro-1 head

Sandwich Shop Shark Buck 2A

SureFire G2X Pro (ramps up but only comes on in low mode, will not switch to high no matter what)



In the case of the Solarforce MPP-1 and the SS Shark Buck 2A, they are either on or off and didn't really dim when applying pressure to the QTC.



I'll post pictures of this stuff later.


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## Beamhead (Apr 10, 2011)

*Fun with QTC*

I just got some QTC and have had some fun, this composite is amazing.
I modded an EZ123 by using a smaller foam donut to hold the QTC in. 






And here is a video comparing the EZ123-QTC to my V10R-Ti.
The EZ12-QTC is on the left, it goes lower than the V10R-Ti but as can be seen it is not as smooth throughout ramping up or down. Excuse the shaking it was cold out.

http://www.youtube.com/watch?v=h8a8KXJxkkw


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## kevinm (Apr 10, 2011)

*Re: Fun with QTC*

Cool! How much does that stuff cost?

Kevin


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## Beamhead (Apr 10, 2011)

*Re: Fun with QTC*

Thanks, I got 10 pcs for $8.00 on CPFMP.


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## jabe1 (Apr 10, 2011)

*Re: Fun with QTC*

Nice Video...had to watch the fish-slapping also :thumbsup:

I've been using QTCs in a few Peaks for a little over a week now and it totally changes the usefulness of the lights. 
I don't have a meter, but I suspect they do suppress the max output a bit.


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## MikeE (Apr 11, 2011)

*Re: Fun with QTC*

HI, I also have been experimenting with peaks and am excited! I just woke up with a vision of a QTC mounted on a Malkoff MD2 retaining ring. IT WORKS! An infinitely variable Malkoff. But I need to design something to prevent friction damage as I tighten the head to adjust levels. Anybody get them to work in anything else yet? They do have some resistance ,so they must be dimmer,but I don't think I can tell for sure just by looking. The trade off is a few lumens for total control and so far I'm thinking it's well worth it. This is coming from someone who likes bright lights. I'm sure the moonmode guys are going to feel the same way.


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## dealgrabber2002 (Apr 11, 2011)

*Re: Fun with QTC*

Beamhead, where did you get those foams for your EZ123? Thanks.


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## Beamhead (Apr 11, 2011)

*Re: Fun with QTC*



dealgrabber2002 said:


> Beamhead, where did you get those foams for your EZ123? Thanks.


They are Arc AAA foam donuts that I got from a generous CPF-er.


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## dealgrabber2002 (Apr 13, 2011)

*Re: Fun with QTC*

Do you think the QTC will work with the E01?


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## shao.fu.tzer (May 10, 2011)

*Re: Playing with QTCs*



PCC said:


> I'll post pictures of this stuff later.


 
Well, did you? I'm fascinated by this new technology and am very curious to see pics and even videos of your mods in action. If you find the time, please do show us, because I'm seriously considering using this material for a forward clicky switch with infinite brightness. The data sheet lists the compression life cycle (depending on the source) as either 1,000,000 or >1,000,000... I imagine no normal clicky would withstand a million presses... Anyway... old thread... I know... pics now please!!! 

Shao


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## JS_280 (May 10, 2011)

Looking forward to more of your findings. I'm really excited about the possibilities available with QTC...


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## Zendude (Jun 25, 2011)

*Re: Fun with QTC*

Hey BH, sorry I'm late to your funtime. ;p

Couple questions: Did you remove the spring? How did you secure the qtc? Conductive adhesive? Or is the doughnut is holding it in place?

@dealgrabber: I had planned on putting some in an E01 but the problem is it only turns on when the head is tightened down all the way. You wouldn't be able to increase or decrease pressure on the pill.:shrug:


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## Beamhead (Jun 25, 2011)

*Re: Fun with QTC*

Just the foam donut, it wont work in my E01 or any base spring type lights.


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## badtziscool (Jun 25, 2011)

*Re: Fun with QTC*

So did you just put the QTC in between the contacts of the head and battery? And the concept is that the more you twist, the more the QTC is compressed, and thus more current is let through? Maybe if it was sandwiched between two metal plates that would allow for a smoother adjustment?


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## TooManyGizmos (Jun 27, 2011)

*Re: Fun with QTC*

~

Hi Beamhead ,

I'm expecting my QTC material tomorrow (monday)...

I have HI expectations of this working WELL in my twistie Fenix LD15 AA ,
which is a 2 level light ... but it starts on Hi .... so it should work.

I explained all the details in Smarkum's QTC thread on MP .

If you have a Fenix LD15 ....... you should give it a go .

Other than Peaks , do you know of any other good "battery crusher" candidates ?
Does the EZAA and EZ123 have a battery spring ? I don't own them .

Thanks / TMG

~


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## Beamhead (Jun 27, 2011)

*Re: Fun with QTC*

The EZ series have a small spring on the PCB for 2 level operation which IMHO make the QTC work better, there is no spring in the body.
I have also used it in Fenix P1CE's not the D , the first I put in the foam ring in the body and it works fine but the pill falls out on battery change so I got a Caig Circuit writer pen at ratshack and "glued" it in place and so far it holds, I tried the same trick on the positive contact but the twisting force pulls the pill loose, an Arc foam ring on the positive contact works great.


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## TooManyGizmos (Jun 27, 2011)

*Re: Fun with QTC*

~

It worked OK in the Fenix LD15 ............

But I'm kinda worried about "parasitic drain" .

I'll be testing for that for a few days.

~


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## Burgess (Jun 28, 2011)

*Re: Playing with QTCs*



JS_280 said:


> Looking forward to more of your findings.
> I'm really excited about the possibilities available with QTC...


 

Me too !


lovecpf
_


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## gswitter (Jun 28, 2011)

*Re: Fun with QTC*

Sounds like a nice replacement for the Fire~Fly 2-stage switch (same functionality as the switch in the Malkoff 2-stage ring).

_Edit: Might work similarly for other twistys that have a spring at the bottom. I'm curious about the direct-drive JIL lights.

Edit [2]: Come to think of it, y'all are focused on the wrong end. Try replacing the spring on just about any tailcap: momentary on (or off) plus variable output.
_


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## Toohotruk (Jun 28, 2011)

*Re: Fun with QTC*

This stuff really looks cool! Can't wait 'til mine shows up later this week! :naughty:

I'm excited that it works in the MD2! Have to think of a way to protect it from damage from twisting. :thinking:


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## kevinm (Jun 29, 2011)

*Re: Fun with QTC*

I was playing with my QTC (thanks Shelby!) and noticed something cool: QTC is magnetic! I have a Matterhorn with the 10180 body that I use with NiMH 1/3AAA's and a slim magnet. It holds the QTC in place! 

Kevin


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## shao.fu.tzer (Jun 29, 2011)

*Re: Fun with QTC*



badtziscool said:


> So did you just put the QTC in between the contacts of the head and battery? And the concept is that the more you twist, the more the QTC is compressed, and thus more current is let through? Maybe if it was sandwiched between two metal plates that would allow for a smoother adjustment?



I always thought the same thing... If you soldered a small spring with a slim metal disc soldered to the end and placed it over the QTC pill, then it would eliminate most of the torquing force on the pill - as the body is twisted, the battery may twist as well, but the spring would just compress - problem solved.


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## Burgess (Jun 29, 2011)

*Re: Fun with QTC*

Great QTC thread !


Thank you, everyone, for the tips and information.


lovecpf
_


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## TooManyGizmos (Jun 29, 2011)

*Re: Fun with QTC*

~

:tinfoil:... Place a circle of Tin Foil over the QTC to eliminate friction ...:tinfoil:

~


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## PCC (Jun 29, 2011)

*Re: Playing with QTCs*

Unfortunately, I've lost interest in trying to do anything with QTCs for the time being. My main reason for using them was to get an extremely low low out of a light or two, but, I've noticed that the light output would drift brighter after setting the light to some rediculously low level after about 30 seconds. I may try putting a QTC in a little project light that I have in the works to see if I can make it work better for me, but, I haven't really done anything with them in a few months and I've even sold most of them off recently.


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## TooManyGizmos (Jun 30, 2011)

*Re: Fun with QTC*

~

Now I'm wondering if I can make this work in ShiningBeam S-Mini's I just acquired ?

The last 2010 model XPG ... w/pill in the head & spring on the PCB + .

any opinions ............... could it work ?


Will I have to remove the PCB spring to make it work ?

Then something solid to take the place of the spring ... inside a foam ring ?

~


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## PCC (Jul 2, 2011)

*Re: Fun with QTC*

No, it shouldn't work. The S-Mini uses a variation on the Shiningbeam Perfect regulation driver and that driver will kick into low mode thinking that the batteries are drained. I'm not sure if you can regulate the voltage in the low mode on that light as my Perfect Regulation driver is now a single-mode light that will switch to low mode only when the battery voltage is low.


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## TooManyGizmos (Jul 8, 2011)

*Re: Fun with QTC*

~

Naaaa ... could not make it work on S-Mini or a Q-mini AA .

Also did not like it's operation in a Fenix LD-15 .... so I removed it .

It changes it's conductive resistance and wavers up/down during use .

Can't really be sure when it's un-screwed enough to not be conducting ?

It can be OFF ...then suddenly after minutes ... the LED starts Glowing !

Can't really find a good application for it .... in the lights that I own .

Too concerned about it eventually becoming a parasitic battery drainer .

Peak lights must be the best application for it ........ don't have any .

~


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## TooManyGizmos (Jul 8, 2011)

*Re: Playing with QTCs*

~

Yes ..... the "Drifting" to higher output after a few seconds or minutes , that you mentioned , is what killed it for me . It wavers too much !

I think I have the light OFF .....then it comes back ON .... !

Battery drainer !!!! ........... I'm done with it .... Can't use it .

~


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## alfa (Jul 8, 2011)

*Re: Playing with QTCs*

I'm playing with QTC on my EZ123, but I've some problem with the drift to higher output. I think it's due to the small elasticity of the battery.

But here some pics:naughty.

First I've made with aluminum sheet a little dish to cover the positive spring and a little shaped washer made of acetylene from a gloss sheet (I don't know if their name is correct...): 













And here the QTC pill stuck in the washer:






And, not shown, all is covered by another dish. The first prototype had aluminum dishes, but the new one has dishes from a thicker sheet of copper.


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## Norm (Jul 8, 2011)

*Re: Playing with QTCs*

Two similar threads Merged. - Norm


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## alfa (Jul 8, 2011)

*Re: Playing with QTCs*



A little video (in Italian) when I show how is possible to dim the output :wave:


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## Beamhead (Jul 8, 2011)

*Re: Playing with QTCs*



TooManyGizmos said:


> ~
> 
> Yes ..... the "Drifting" to higher output after a few seconds or minutes , that you mentioned , is what killed it for me . It wavers too much !
> 
> ...


 
The only drifting I experienced is when trying to get ultra low, you have to sneak up on it.
I guess you don't like it?


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## TooManyGizmos (Jul 8, 2011)

*Re: Playing with QTCs*

~

Beam ... yes , you are correct , I don't really like it .

I can't be sure when it's turned OFF enough - not to come back on .

I don't have any lights that are appropriate for it .

I will be giving my QTC away in MP for other members to try out .

Later / TMG 

~


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## Helmut.G (Jul 9, 2011)

*Re: Playing with QTCs*

hey alfa, thanks for the cool video! I didn't understand a word but the pictures are telling more than enough!


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## alfa (Jul 9, 2011)

*Re: Playing with QTCs*

I could try to do a video with English words... But I think you would understand even less :laughing:


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## smarkum (Jul 10, 2011)

*Re: Playing with QTCs*

I don't get drifiting into higher levels either in the lights I've tried. . . and my 38DD doesn't drift; although, it has the little qtc holder piece. I've not noticed drain but I'm always sure to give mine a good turn prior to putting it in my pocket. 
I just tried it in my Fenix 01 and it worked! Now, why I would want that awful tint and low level any lower . . . but it was fun to try!


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## smarkum (Jul 10, 2011)

*Re: Fun with QTC*



shao.fu.tzer said:


> I always thought the same thing... If you soldered a small spring with a slim metal disc soldered to the end and placed it over the QTC pill, then it would eliminate most of the torquing force on the pill - as the body is twisted, the battery may twist as well, but the spring would just compress - problem solved.


 
You working on this Shao? Sounds like it would eliminate some of the perceived problems . . .


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## flashmenow (Jul 12, 2011)

*Re: Fun with QTC*

Hi all. Here is a short clip of QTC in action in my Peak. Will try to get a better video up. QTC was placed at the bottom of the battery tube on the brass screw center.


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## RCantor (Jul 12, 2011)

*Re: Fun with QTC*



Beamhead said:


> And here is a video comparing the EZ123-QTC to my V10R-Ti.
> The EZ12-QTC is on the left, it goes lower than the V10R-Ti but as can be seen it is not as smooth throughout ramping up or down. Excuse the shaking it was cold out.
> 
> http://www.youtube.com/watch?v=h8a8KXJxkkw



Was the QTC emitting a high pitched sound making the dog upset?


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## RCantor (Jul 12, 2011)

Oh, I knew I had a serious question... 

With the QTC in a single mode light - when you run it on low does the runtime increase or does the extra power turn to heat or both? If both any idea what % goes to heat vs what % is increased runtime? Thanks.


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## houtex (Jul 12, 2011)

*Re: Fun with QTC*

Disclaimer: I'm really dumb when it comes to these kinds of workings.

That said,would this work with an Oveready ZeroRez tailcap? I think that would be the coolest.


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## PCC (Jul 12, 2011)

*Re: Fun with QTC*



houtex said:


> That said,would this work with an Oveready ZeroRez tailcap? I think that would be the coolest.



No, it can't easily be incorporated in a ZeroRez.


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## archimedes (Jul 12, 2011)

RCantor said:


> Oh, I knew I had a serious question...
> With the QTC in a single mode light - when you run it on low does the runtime increase or does the extra power turn to heat or both? If both any idea what % goes to heat vs what % is increased runtime? Thanks.


 
Run-times are very long with QTC set to low output. There is a thread posted in the Peak sub-forum documenting a single CR123 primary cell lasting for over 376 hours in a Logan QTC model.


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## RCantor (Jul 13, 2011)

Wow! Thanks for the reply.


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## shao.fu.tzer (Jul 13, 2011)

Beamhead said:


> The only drifting I experienced is when trying to get ultra low, you have to sneak up on it.
> I guess you don't like it?



Same here... getting a really low low without drifting is tough... It seems to work beautifully in the mid-high range though... 



smarkum said:


> You working on this Shao? Sounds like it would eliminate some of the perceived problems . . .



Yes, along with a few other QTC projects. I've been spending so much time trying to implement this into a clicky, that I haven't had time to list new inventory! I'm determined to master this material! It's interesting - I just checked the Peak thread and saw that they came up with something similar to one of my early QTC pill twisty protectors - a ring of foam cut to the height of the QTC pill with a metal disc glued to the rim of the foam. It protected the pill nicely, but the torque eventually ate up the foam. So now I'm experimenting with springs. I'll keep everyone posted.


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## flashmenow (Jul 13, 2011)

Hi all on the market place I purchased a 12W RED LED to use as a future mod into a light.

Today I was playing around to power it up (crudely) Using a CR123 and placing the QTC square on top of the positive terminal and applying pressure to activate.

When I build this light I am going to facilitate the QTC into a pressure switch to use as well as having a on/off clicky. 

Enjoy the new video. Glenn


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## edc3 (Jul 13, 2011)

Anyone tried this material in a Fenix E05 yet? I've got some QTC on the way and I'm thinking whether I want to spend money on batteries for my EZ CR2 or put that towards an E05 that I can run on Eneloops. A continuously variable floody keychain light for $20 is very appealing to me.


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## Zendude (Jul 27, 2011)

Well, I had a little bit of success with the E01. I cut down a spring from another host and formed it as best I could around a AAA battery. I then placed the spring in the body where the negative terminal on the head mates . I removed the tail spring from the E01 and replaced it with thin washers until the positive terminal was just above the negative contact. I was able to vary the brightness but I still had contact issues.

I had some success with my Ti Quark AA as well. I placed a cut down screw inside the tailcap spring to make it bottom out prematurely, programmed the light for loose/turbo and placed QTC on the positive terminal. I was able to vary brightness while retaining clicky functionality(because it's Ti, you could also keep the head tight and vary the brightness by loosening/tightening the tailcap). It still needs some refining though, because the spring caused inconsistent ramping. I also center punched a penny(to give it a cone shape) and placed it between the tailcap and body. Ramping worked nicely but you loose the clicky.

My hope is this will spark some ideas in a more competent modder.:candle:


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## PCC (Jul 29, 2011)

*Re: Playing with QTCs*

So, I finally got off my lazy behind and finished a QTC mod that I had started months ago. It's a simple aluminum ring that I cut on the lathe that fits between the end of the body of a SureFire 6P and the tail cap. The Z41 tail cap has been converted to a McClicky and the drop-in is the ThruNite low voltage 1.5A three-mode XM-L. The ring has a strip of stick-on foam that is used to prevent the twisting action from torquing on the QTC so that it may prolong the life of it and to help hold it in place as well as to help smooth out the transition as it ramps up or down. The foam itself started off thicker than the QTC, but, has been compressed to the same approximate thickness from being installed in the flashlight. On to the pictures:

QTC ring sitting on the bored 6P ready for me to install the tail cap.






Another shot so that you can see how it fits together. Can you find the QTC in this or the above picture?





Here's an interesting shot. The right light is a Quark 123T on moonlight mode (0.2 lumens), the middle light a Ra Clicky 120 on the lowest low (0.08 lumens), and the left is the 6P on low with the die of the LED barely emitting any light because the QTC is only allowing a trickle of current to the LED.





The only thing about having the light putting out this little light is that it will ramp up on its own slowly over time and the light will be about as bright as the Quark after about a minute or so.


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## Helmut.G (Jul 29, 2011)

*Re: Playing with QTCs*

thank you for posting this, PCC :twothumbs


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## eyeeatingfish (Aug 12, 2011)

*Re: Playing with QTCs*

So where can we buy the QTC material? I found a website in England but shipping is of course a lot to America and there is a minimum order but the QTC pills are relatively inexpensive. You would have to order a lot.


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## emu124 (Aug 12, 2011)

:wave:

Try it here: 

http://www.cpfmarketplace.com/mp/showthread.php?253272-F-S-QTC


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## smarkum (Aug 20, 2011)

I've got PLENTY left if anyone still wants more . . .


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## kramer5150 (Aug 22, 2011)

Does QTC work with Incans?

I have a SF-G2 thats been modded with a rev-clicky and larger 2x O-rings at the tailcap. So even with the tailcap unscrewed its really tight, firm and seals out water from moderate splashes.

thanks!!


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## MosesM (Aug 22, 2011)

kramer: QTCs should work with incans as well since it only affects resistance.


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## Helmut.G (Aug 23, 2011)

In principle they work nicely with incans, but it can be hard to get a light to work with QTCs that wasn't designed for it.


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## Linger (Sep 4, 2011)

re: Incans - there's a chance QTC will be the ideal soft-start medium, slowly ramp-up the energy until the filament lights, gradually tighten towards to overdrive as desired, but little of the associated resister losses of other methods.


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## smarkum (Sep 10, 2011)

I've got *20 packets* of QTC left for those interested . . .


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## jasonck08 (Sep 10, 2011)

I'm wondering if some type of electrically conductive epoxy could be used to secure the QTC's in place. Anyone try that?


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## smarkum (Sep 12, 2011)

jasonck08 said:


> I'm wondering if some type of electrically conductive epoxy could be used to secure the QTC's in place. Anyone try that?


 
There is some info on the electrically conductive epoxy securing QTC in the original 38DD thread started by KUKU 327. . . as I recall, the epoxy idea had some faults.. . . 


18 packets of QTC left.


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## PCC (Sep 20, 2011)

I thought about this quite a bit and came up with another mod incorporating QTCs. I started with mydaughter's 4Sevens Preon with the twisty body. The tail cap can be removed on this light and it only holds a spring. Here's a picture of that light before being modded:







This is the stock tail cap next to the QTC parts:


















Here's the light turned on at a fairly low level. The second picture is the same picture, but, with the flash turned off so that you can see that the flash didn't contribute to the the glow of the emitter:











Here's how the light looks now with the QTC modded tail. The head is tightened down all the way and the tail cap is now used to turn the light on and off.






You can still switch modes using the modded tail cap and tightening the cap tighter will increase brightness to the maximum allowed for whatever mode you are in.


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## Burgess (Sep 21, 2011)

to PCC --


Brilliant !


:thumbsup:



Just wondering . . . .


Any current drain, when the flashlight is "turned off" ? ? ?


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## PCC (Sep 21, 2011)

Not that I'm aware of.


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## borrower (Nov 21, 2011)

Just wanted to share my trials+tribulations... this is an external control for a headlamp using QTC. http://forums.mtbr.com/lights-diy-do-yourself/qtc-infinite-variability-730630.html 

You'll have to read through a couple of failures before getting to the version that worked. 

While the exact construction won't drop right into a flashlight, I hope this can spawn some good ideas.

And for the record, a Lummi Wee with QTC is easy (literally just drop the QTC on the battery and screw it back together) and awesome.


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## PCC (Nov 22, 2011)

Burgess said:


> Just wondering . . . .
> 
> 
> Any current drain, when the flashlight is "turned off" ? ? ?



Turns out that there is current drain if you turn it off but the battery doesn't rattle. My daughter drained two batteries this way before I converted it back to the original configuration.


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