No problem. PM me and we'll sort it out.

The glue turned out to be a bad idea, as I ripped one piece because of the constant friction. Right now the QTC piece I have in my E07 is just being held in place by the friction of the battery. The E07 has polarity protection in the form of a small cavity in the pill where the positive post of the battery goes - it seems to work well enough.

I'll have to think up a sandwich-type holder for the tail section.

That was the problem I came across.

A couple of thin 14-14.8mm conductive discs sandwiching it would be the best bet. I've tried various coins with no success. The material is very soft.

Looking at a UK 5 pence coin, it is a little too large, but close enough I can file it and is thinner than the pill. A 4mm hole in the middle of that might work.

This is just thinking at the keyboard which I was always taught in my Computer Science classes thirty years ago was a Very Bad Thing To Do.

The 38DD had a foam centering ring.

Unless my E07 is unusual, there should be a foam spacing ring at the bottom of the battery tube that keeps the battery from touching the -ve contact when you twist the tail into the locked position. I figure one of these QTC pills would stay put a little better if you were to put it into that ring rather than at the +ve button. It also wouldn't be subject to the head's twisting action if it were glued down there.

Neither of my E07s have those foam rings in them. Would be nice if they had....

Yeah, my E07 doesn't have the foam ring either or that's the route I would've gone. As it is I use the tail lockout switch to turn the light on and off instead of the head. Doing it this way also shields the QTC pill from twisting action. It's the compression force of the battery that causes the friction problem.

That's sad news if I ever want to get another one. I'm not sure how the light would avoid battery rattle when off without it.

The foam ring was the way to go!

Mine is far from pretty, but it works. I just cut a thin piece of foam I had lying around and made a small hole in the middle to hold the QTC pill. Works brilliantly!

Thanks folks, especially frills, for the inspiration.

Told you it wasn't pretty. I put a tiny dot of epoxy on the foam to hold the pill in place. Didn't work all that well. A certain amount of care was required when inserting the foam.

Video uploading as I type.

Head or tail? Any pictures?

Tail. Pictures and YouTube bit uploading as I type. The video may take a while to be available - YouTube can be horribly slow sometimes.

See Post 28 above in a while.

Pics, pics, dozen of pics :p Very, very interesting thing, this QTC :O Thanks for the info.

It's not all that interesting looking - it is a small black square of rubbery material about 4mmx4mmx1.5mm

Yeah, I know. But still... with a small piece of rubbery you have multimode light :D

Is it possible to get a tail current measurement at say light, medium, and full pressure? At light pressure, it should be almost 100% resistance, so the LED won't draw hardly any current and the draw should be low. Then at full pressure, the resistance goes to zero despite the higher current draw. But in between the QTC should get hot from dissipating a significant chunk of voltage at a reasonable current.

How does full brightness compare with and without the QTC? Does the resistance go to zero with a reasonable amount of pressure?

The vF range of the LED is so narrow that the QTC will never be dissapating high current at high voltage.

With the E07, it would be close to impossible to measure current draw.

I can compare maximum outputs though as I have two of them. With NiZn cells I got 436 lux at switch-on in one and 440 in the other. The one with the QTC in it was the 436 lux one. Variations of 5-10% wouldn't surprise me.

Got 410 lux from the one without QTC and 370 from the one that had it, so roughly a 10% drop in output. The absolute numbers would be higher if I'd charged the NiZn cells in the last three weeks.

The one on the left has the QTC in it, the one on the right doesn't. I had to check that repeatedly as my eye couldn't really see a 10% difference even side-by-side.

I'm fairly positive that heat will not be an issue - this stuff either passes current or does not, the probability of its passing current varies according to the degree of compression.

It is like putting a constriction in a pipe so it may not heat up as much as might be expected. I seem to remember that a single pill can handle ten or so amps. I'd need to dig through the MUTR website to find out.

I can probably rig something up to check this at the weekend. I can sandwich a thermocouple between a couple of pills, stick it in a vice and run current through it to see what happens at varying degrees of pressure

Damn awesome idea, Don. I ended up using a circle cut out of craft foam (my wife is an artist and has tons of the stuff). Works really well now.

The manufacturer state that the pills can be used at up to 10A @ 40v, unless they are big fat liers I don't think we're going to have a problem :)

Not sure if it's a good idea, but I'll throw it out there anyway :P

I think the biggest problem would be the pill being ripped over time due to the twisting action. Using conductive glue (here) to attach a very small metal plate to it might help stop that. You could also glue the pill in place.

This would be a nice mod for the ITP EOS A3 too (the one without modes I mean)