My QTC controlled light

I've had an idea about using QTC for a loss free driver ( If you dont believe that then please RTM on the stuff)

and an idea about how to make it work too.

So here is take 7 or 8. Which is my best so far.

First a few pictures where i show the variable output as best I can with pictures :-)

And all the way up to stupidly blindingly DD XML from 4,11 V trustfire 3000 mAh output with the qtc bypassed.

A different distance/angle/shot because it would not make any sense any way else :-)

How I did it? Stay tuned.

I used a copper pipe OD=10mm ID=8mm final lenght is 8,25mm

A piece of plastic rod OD 8mm center drilled with a 5,5mm drill because that is the closest standard drill size to the diagonal size of the QTC pills.

A copper plate/foil about 0,5mm thick cut and sanded to a circle of 10mm diameter.

Then solder the copper plate to the copper pipe.

Then press fit the plastic piece inside the pipe.

Then i made 2 pieces of OD 5,5mm*0,5mm thick brass discs and one post OD 5,5mm height 4,75mm final length.

Soldered the post to the clickie switch where the spring used to be. I had to try a few time to avoid using too much solder. If I use too much the solder makes a slope up the sides which impedes the function.

Here in the picture you also see two QTC pills all worn out in 1 day. I learnt something by that - do not add any lubricant to the QTC, the brass disc/post or anywhere near that. it will make it less well working and your QTC will be squished flat in no time!! Lesson learned ;-)

Then assemble like this

1st QTC, then brass disc then QTC then last brass disc

Now I build the light and CAREFULLY (at least 2.nd time around :-) place the thingamadoo on the brass post.

Note that nothing prevents the content nor the thingamadoo itself from falling off the post if I tip it.

Here it is before it is put back in the light.

And here inside the light.

And it goes low!


I like it .

I have high hopes for QTC .

After having had this for a few days I've noted some things down.

I often end using the light around the 30-65% area. Rarely lower nor higher.

I am annoyed that the tailcap needs two hands for adjusting brightness if I want to go past 50-55 %.

The threads on the light will most likely give up in a few months. They are suffering and no amount of lube seems able to save them.

There are some large variations in output with very little explanation other than it lies in the "Quantum Tunnels" and the probability of their passing current. What I mean is that a certain amount of twist will not give even nearly the same light output each time.

And in the really low mode the threads have enough slack (and it will get worse) that a press or pull on the tailcap will have a large impact on output. From moon low to maybe 7-9% output. That feels like a LOT OF LIGHT MAN! BLINK BLINK Night vision impaired for a moment.

So am I happy?

Yees well sorta. I hate "modes" in flashlights. I feel I always go

I need low - whooom - the thing goes high-med-low-strobe ( %ยค#!!#!) click - click click

I need high - peep - the thing starts in low. click - click - click

And this is super compared to that c#@p

But the lack of linearity is bugging me and i HATE that it goes from moon low to 10% in a blink of an eye

But there is of course a reason why it is type 7 I am showing and not #1. That was far worse.

This is quite good.

JB weld works great for restoring threads. Apply sparingly to the side w/ the worst threads (after cleaning w/ solvent). apply good release agent to other piece/threads, screw together. I've repaired stripped lawnmower spark plug hole threads this way.

edit: just remember, it isn't a good conductor, so you have to have some exposed aluminum if that's where the electrical path goes...

I know first hand of the inconsistency with QTC. I finally gave it up and decided that even "modes" were not as bad as the ever changing QTC brightness. Wait till it starts to wear more and starts to break up. Then you will see flickering and that was the last straw for me.

Good luck with it. I really hope you find an answer, or someone does. I think in the long run, a "pot" (dimmer), is the only way although it is a heat and power hog.

If you find a driver where you can identify the "sense" resistor then add your pot there.

Will not take but a fraction of the power compared to any direct connection approach :-)

Thanks, I will have to look into that.Smile