QTC flashlight - from scratch (non battery-crush)

[Harry999]

That is exactly why I am interested as well. This looks like a potentially great emergency light. I love simple twisty lights especially those with a progressive UI. With less moving parts I feel more confident in the light.

With a smooth ramping QTC based control it will be a nice EDC as well...

I admire you skills. I could not do any of that. My limit is filing out the holes on a Ti clip to fit it on my Jetbeam E3S.

Sent from my GT-I5800 using Tapatalk 2

[^Gurthang]

Really impressive work Fraz, very well finished. I'm curious where you're sourcing the QTC and waiting to see more of you work.

[PhotonFanatic]

. . .

As far as the way the qtc brightens and dims this prototype, it works very smoothly with no flickering or artifacts. A good example if you have a QTC pill - make a circuit with wires running to and away from an LED. Put the pill on the + end of a battery and the - wire on the negative end of the battery. Press the + wire into the QTC directly, it gives you an idea of what the material is capable of. Ramps like butter when you don't have to worry about movement of the pill or shearing force. I'll try to make a little better video showing the operation if I can get a little time tonight.

. . .

Care to elaborate a bit on the interface you are using between the QTC and the positive and negative leads? How are you avoiding abrasion as you mentioned--is the contact from the +ve end of the battery a piston, i.e., no twisting, just pressure to the QTC?

[TheFraz]

Thanks for the compliments! Sorry it's taken me a bit to respond - been pretty busy lately. To answer your questions, I got the QTC a while back from an online vendor (that I cannot remember the name of lol...although it says "Rapid" on the plastic bag they came in, if that helps). Yes, I'm going for very few moving parts and as little soldering as possible. I want it to be very durable. As for the QTC interface, it has taken a lot of R&D to get it right. All the parts for the user interface/engine have been fabricated. It seems most solutions that look good on paper don't look or feel so good in operation. I'm still working out final bugs on my engine design now (have given it several thousand twists to try for any failures that might happen) and hopefully I can tweak it to the point I feel it very unlikely to have any abnormalities when reproduced (can't go into too much detail yet, but I'll take some pictures of the final engine). The main trick I wanted was to have constant contact with positive and negative springs to the battery so it wouldn't rattle when the light is in the 'off' position.

And since I like pictures, here's the QTC123 next to a LD10 for a size reference:



Now I'm waiting on my parts/aluminum to arrive for my final couple models. I also wanna add some warmer LEDs...I just really like the warmer colors that have come out recently.

[Mattaus]

Use Nichia 219s for your LED. I love those emitters. Any consideration for other metals like copper or even titanium? Sorry if this has been covered....I'm on my phone and searching is a pain.

Also count me in if you produce the CR123 versions.

[TheFraz]

Yeah, I'd definitely like to try the new Nichias out...I haven't seen one being used yet but I've heard nothing but good things. And yes, I'd definitely consider other metals. It shouldn't be too hard to incorporate them once I finalize the design.

[Lumenz]

Any updates on the progress? I will be monitoring this thread. I have been getting the Peak QTC lights but they are not exactly what I was hoping for. I like the smoothness of operation of your flashlight.

[TheFraz]

Any updates on the progress? I will be monitoring this thread. I have been getting the Peak QTC lights but they are not exactly what I was hoping for. I like the smoothness of operation of your flashlight.

Thanks for the interest! Sorry it took a while to respond. Finally got my materials in. Got a chance to get on the lathe tonight and finished the optic holder/heat sink for the next prototype.



On paper the bug fixes look good...we shall see. I've been using the other 2 prototypes like crazy and they are holding up great. Hopefully I can put some pics up later for this model 2.0 light. It should be better in every way than the 1st one.

[Harry999]

Look forward to the pics.

[persco]

Wow. What a great thread. Impressive work, Fraz. I'll keep a close eye on your progress.

[wolfy]

[gunga]

Very cool. I am following this cool thread.

[Phototropin]

Love your work, it's coming along very well.

Does the light flicker at all? I have used QTC at work to make basic pressure sensors, and found that when I apply intermediate pressure I cannot get a stable resistance/conductivity measurement (keeps fluctuating and won't "settle"), so I'm limited to using it basically as an on/off switch instead instead of a variable resistor.

I did a quick google search for "Rapid QTC", and by the results (if it is indeed the same product) it appears to be a similar product to mine (silver nanoparticles in silicone I think). Does your QTC just look like a thin (~1mm) browny grey rubber?

Awesome looking light BTW, I hope you keep the final design as simple as that. (But maybe in Ti, Cu or brass... )

[TheFraz]

Thanks guys. As far as flickering, that was one of the biggest problems to overcome because the QTC reacts to such small changes in pressure. And if there is any binding it readjusts eventually as you are describing and loses stability. It has to be implemented just right to get it to work reliably and in a way that is pleasing to the eye. Lots of ideas seem good...until they are built lol. It's taken me about 13 prototypes to get a couple that work like I had imagined they should. Yes, the raw QTC looks like a tiny wafer of rubber. I plan to keep it simple looking in final stages...well, because I love minimalism . It's just so hard to make something simple with a clean look and design that works, it's frustrating. Below is a video of the smaller of the prototype doing some small incremental brightness shifting to try and show the stability of the engine. The only thing that limits how smooth the light ramps is how smooth your hand can turn it (and as my hands are pretty big I struggle to get fine movements on this tiny light). But to reinforce the idea, I have left it on at around 50% brightness all night, then in the morning slowly ramped it down to see if there is a 'rebound.' There is not - it works great.



-Fraz

[Phototropin]

That's fantastic Fraz, very smooth. I have noticed in my tests that it takes a little while to "break in" the rubber, so will be interesting to see if your max and min output notches (if you were to mark the outside of the flashlight with those intensity bars referred to earlier) change over time as the rubber is put through repeat compression and decompression cycles.

I'll be keeping an eye on this thread, very cool TheFraz, very cool.

[TheFraz]

Finally finished the latest model. This one is quite a bit smaller at 4.5". It also is lighter, brighter, and uses a warmer LED. But the thing I like about it most is that it now requires a full turn to go from full off to full on. Much much better feel. Here are some pics - I'll try to post a video tonight after I grab something to eat (starving lol). The bottom one shows the size difference from the old model. Also, this new light will look different when I 'finish' it...still have a bit of cutting to do on the body before I coat it.




-Fraz

[gunga]

Very cool! I think I want 1!

[XFlash]

Been enjoying this thread, love to watch a custom light in its progress.
I love this design, I want one also.
A low low is important to me, and this light seems to have one.
Thanks

[Walterk]

Looks great!
And I love the idea of low-tech ramping up the output.
It would be easy to build something with the same effect with using resistance wire, a build-in variable resistor.
Wonder how QTC holds over time. QTC is the bomb if they give life-time guarantee. And no losses converted to heat!


How reacts the QTC when you stack 4 pads on top of each other, would that just require more force to get zero resistance?
Then it could also act like a variable resistor, also useful when you don't use QTC for a ramping-switch.
Less losses and easy to incorporate in a build, re-adjustable in case you change to the-led-of-the-moment.

Would love to hear that!

[TheFraz]

Looks great!
And I love the idea of low-tech ramping up the output.
It would be easy to build something with the same effect with using resistance wire, a build-in variable resistor.
Wonder how QTC holds over time. QTC is the bomb if they give life-time guarantee. And no losses converted to heat!


How reacts the QTC when you stack 4 pads on top of each other, would that just require more force to get zero resistance?
Then it could also act like a variable resistor, also useful when you don't use QTC for a ramping-switch.
Less losses and easy to incorporate in a build, re-adjustable in case you change to the-led-of-the-moment.

Would love to hear that!

Thanks! So far the QTC is holding up great, and I've been turning it full off and on several hundred times a day to try and get it to wear out. But if if does eventually wear out, I've designed the engine where it should be very easy to replace the QTC with a new square. Simply take the old one out and drop a new one in - no tools required. However, I really don't think it will wear out during normal use only taking direct vertical (non-shearing) pressure. The company website claims something like one million compressions, and although that sounds a bit optimistic, I don't have any reason to not believe them. I haven't tried stacking the pads on top of each other, but yes I imagine it would work relatively the same but requiring more force to reach zero resistance.

Attached are a couple more videos showing the operation of the latest prototype. It now requires one full turn to reach full brightness. This makes it much easier to obtain a brightness level you're wanting - it also requires much less force to turn. It's a little difficult to tell in the video because of the camera's exposure changing as the light gets brighter (and the iPhone isn't the best camera), but you can get the idea. Also attached is a video showing the light being used outdoors.





-Fraz

[^Gurthang]

Fraz,

I'm even more impressed w/ your abilities, the newest prototype is VERY impressive. I like your idea of a nearly full turn to go from off to full on, an elegant UI. I'll keep watching enviously of your work. Good luck.

[TheFraz]

Thank you for watching the progress ... persistence is definitely paying off on this one. I included a better quality video of the version 2.0 engine on the front post, but here it is again:



I really like the way it is turning out. Feel and size are much better now. I'm eagerly awaiting some new materials to come in for some new and interesting battery and materials combos. I've definitely learned how not to make a QTC light in a few dozen ways.

-Fraz

[Mattaus]

I've been following this thread from the beginning so I'm super keen to see where this heads....but if I can just ask a few questions and make some observations:

1) Awesome UI. The ramping is so smooth!

2) Does it need to be so...'fat'? Seems like the head is way over-sized for the optics, or is that a trade-off for the QTC functionality?

3) What size cell is in use in the light above?

4) You're original design with the matching body sizes and notches was great - will that make a return?

I realise your latest version is a work in progress given the pen marks so I look forward to seeing it nearer completion!

Keep up the good work

- Matt

[TheFraz]

I've been following this thread from the beginning so I'm super keen to see where this heads....but if I can just ask a few questions and make some observations:

1) Awesome UI. The ramping is so smooth!

2) Does it need to be so...'fat'? Seems like the head is way over-sized for the optics, or is that a trade-off for the QTC functionality?

3) What size cell is in use in the light above?

4) You're original design with the matching body sizes and notches was great - will that make a return?

I realise your latest version is a work in progress given the pen marks so I look forward to seeing it nearer completion!

Keep up the good work

- Matt

Thanks for following Matt. To answer your questions,
1)Thanks!
2)It doesn't need to be quite so fat. It is that way now because of a few reasons. It uses a 26650 battery which makes it look a little thick, and it is short at around 4.5" which compounds that look even more (also I like overbuilt walls and tend to make them thicker than most). The head looks large because I am engineering this light a bit different from traditional design. All the guts, optic, heat sink, etc. go in from the tail end, so there is no bezel to screw on the top - I made it this way to limit the number of pieces in the design and the possible points of water ingress as much as possible. For this particular light however, I made the internal threading on the head a bit too long, thus the oversized look. Newer ones will have a shorter top section (I don't like the look of the shorter tail/body section as much).
3) 26650
4) Yes, the original design (or a variation of) will make a return when it is finished. This latest one was mainly an exercise in size reduction and engine tweaking to make it smoother. Aesthetics should look better going forward.

-Fraz

[Mattaus]

Thanks for the answers. I'm still in line for one if and when you decide to sell them

- Matt

[TheFraz]

No problem - glad you still like the way they're going! Finished this latest one...looks different without the raw aluminum. Also the 'volume bars' for the brightness level now work, along with a marker bar on top to tell which level you have selected. Here's a pic:

[Mattaus]

No problem - glad you still like the way they're going! Finished this latest one...looks different without the raw aluminum. Also the 'volume bars' for the brightness level now work, along with a marker bar on top to tell which level you have selected. Here's a pic:

[gunga]

Looks great! Would love to see in another battery type. So, there is no circuit? This is direct drive?

[TheFraz]

Thanks! I've got materials coming in this week for additional battery options - drawing out the plans now. Yes, no circuit board - so it is direct drive voltage-wise, with the QTC controlling amperage. Here is a video of the brightness control bars in action - it is finally a repeatable, stable, sustainable engine that can control the brightness with reasonable accuracy. The longest bar is 'off,' as well as 'high.' All the previous models had ghosts in the machine of some sort and would work correctly, but not exactly repeatable from one use to the next:



Please excuse my horrendous cinematography once again.

[manoloco]

This is a very interesting thread, nice results TheFraz

Very interested to know more of it, specially if you decide to make it in other cell types and regulated.

Thanks for sharing your very nice work!