Infinity.... to dim or not to dim.

After failing to locate an appropriate thread, I've decided to just post the question here, and hope that someone will answer it and save me some time.

CMG Infinity, surely many of you will have one and have had it for a while. For me I just received my very first Infinity today along with the Arc-finity adaptor.

Without sounding like another review of the light, it is built like a tank and dimmer than an Arc AAA.

Anyway, to the point. Many of you will know that there is a "hidden" function in this light and that is the dimming function. This is basically acheived by not screwing the head on fully.

Now the question is how does it do this? And what material is that black contact pad on the head? I tested it for resistance and it changes as I change the position of the needles on the black pad.

Hope to hear from someone soon.

YC

I've only had my infinity for about three weeks and did not know that I could do anything other than turn it on or off by turning the head.. Mine also has the black "contact patch" like yours. Is there a hidden feature that I'm not sure how to activate? I did try a lithium AA battery and it was noticably brighter.

Note - It's dark now, so I just compared the infinity with my Arc LE. Both with new batteries, the infinity doesn't seem to be as stupidly dim as people keep saying.

I'm too lazy to take a photo, but it's no where near as dim as this:

Infinity (old?) on left, Arc AAA on right.
(Image borrowed from the Led Museum. Craig, pls let me know if you mind and I'll take it off)

[EDIT] - This is my photo


YC

Take a pencil eraser and clean the top and bottom contacts of the battery and the black pad on the Infinity.

I think you'll find that the "dimmer" setting is gone once you do this. You're probably getting a dimmer light than usual because you aren't getting good contact = higher resistance = lower light output.

Screwing it in tightly gives better contact and you get full brightness.

[EDIT: Hmmmm... Now that I mess with it more, it still dims, but it's brigher in general after the cleaning]

I've had some problems with the Infinity not turning on, or coming on dimly, even when screwed down tight, and I found it was due not to the black contact pad, but the connection of the return to the case, around the perimeter of the PCB. You can check this with an ohmmeter, measuring from one of the solder lands (the one at the base of the Star Trek symbol, not the apex) to the case of the head. There should be 1.2ohms or under if you have a good connection.
I added a circlip fashioned from a paper clip to restore good continuity, which made it reliable. With the connection restored, the apparent "dimmability" aspect of it is greatly reduced, with much more an on/off transition than before. I suspect most of the soft-on problems are caused by this-

If your Infinity turns on and varies brightness with a perceptible rotation of the head, you probably have a problem with the ground connection. The transition zone shouldn't be much more than just a slight rotation, from just-on to full-on.

Even so, I still can coax out a soft transition when lightly screwing it on, unlike the Arc, which is full on or off, so I think the carbon-look material tends to have that characteristic, maybe from a kind of oxidation effect. The Arc has a shiny metal button contact which is either make or break- it shows more of a flicker effect than a dimming effect if you try to get it right at the transition point. As mentioned though, a cleaning of the Infinity contacts does reduce the soft transition range. It's probably best to minimize this by cleaning it.

So does anyone know what the black carbon-look material is? If implemented into the Arcs would that provide the *dimmer* that we always wanted?

YC

I recently tried this and found the dimmer is fully variable. Just turn it real slow. I like this feature. Believe it or not, if it's really dark, and your eyes are well adjusted, full brightness out of the Infinity is not necessary.

I may do a runtme test on this thing at reduced brightness. I wonder how much it would extend battery life? If it extends it a lot, I think this just may be the ultimate backwoods survival light.

Dunno yclo - still looks pretty "stupidly dim" in your photo too! Really there is just no comparison between the two in my book. I'm not saying the CMG is "bad" just certainly not as bright. By a LONG shot. I *like* the dimmness of the CMG for many things.

As for cleaning the contacts to remove the dimming "feature" - I've tried everything, and it still does it. I've never heard a reasonable answer on why it happens. Nor do I know just how bright it *should* be since it just seems to get brighter no matter how hard I crank down on the thing.

I keep my infinity on the nightstand with a glowring attached to it. works great for power outages or just something little to find your way around the house at night. battery cost is negligible.

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by Lux Luthor:
I recently tried this and found the dimmer is fully variable.<HR></BLOCKQUOTE>

I tried mine and got the same results. It's pretty cool actually, and I wouldn't have noticed it if not for reading this here..

I've found that my Infinity has the same dimmer effect. Intentional or not, this has to be 'normal' for an Infinity. Mine is definitely a lot dimmer than my Arc's, also. But personally that's one of the things I like about it - it provides just enough light to get around or read without ruining my night vision or more importantly without waking up the wife so I don't face this !

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by darell:
Nor do I know just how bright it *should* be since it just seems to get brighter no matter how hard I crank down on the thing.<HR></BLOCKQUOTE>

That's a symptom I had when the pcb was poorly grounded - use a DMM to measure the resistance of the ground connection and see if that's the problem. It should read less than 1.5 ohms or so-
It was weird because I would have it on, and not touching it at all, and the light would dim, get brighter, dim, seemingly at random. When it was dim, cranking it down hard still didn't restore it, which indicates to me it wasn't the positive contact, in this case. The positive contact dims it, but the intermittent operation was from the ground return. The black coating adds about 10 to 20 or so ohms to the total (depending how hard you crank down on it); bringing it from about 26 ohms to double that.

Out of my small sample of three, they all developed the intermittent operation problem, until I added the circlip. I returned one to EMS when it eventually wouldn't even light up at all, but that was before I thought to check the power return. I probably could have done the same thing on it instead of returning it for exchange. The replacement worked for a while, then started having that wide squishy turn on characteristic also.
If you have this wide turn on characteristic, that's probably what's happening.
Check the resistance to that solder land and see what you find.

I'm almost sure that's what it is, and I'll check one in moment. What was your fix, exactly?

I had a picture of it posted on this thread:

choosing a mini light

Just take a small paperclip, thinnest one you can find, and use your Leatherman to curl it into a circlip that's a hair larger in diameter than the inner lip of the Infinity case retaining the PCB. Try to make it as circular as possible, and when you slip it into the lip, it should have enough springiness to be retained in there.
The outer edge of the PCB is conductive and part of the ground return node, and by bridging that to the case, the connection is improved. Without the circlip added, I was measuring all different values of resistance to the ground land, probably due to the different pressure on the pcb. Once I added it, (rotate it a bit back and forth as a wiping action), I got a nice 1.2 ohm reading, and the light's soft on transition was very much reduced.
This seems to be more prevalent when the Infinity is not used for long periods at a time, maybe because the high resistance is kept at bay with frequent use, because it pushes the pcb around a bit.

Just give it a try; it's easily reversible and you may get some improvement out of it-

I have just (Right now!) scraped off the black covering. it has taken away the dimming effect! the contact pad is made of copper when the black is removed. the black stuff seems to be a semiconductive covering! as someone posted previously, when the resistance is measured on the black pad, it increases as the distance increases, same thing that happens when you try it on pencil lead. this leads me to believe it is a semiconductive covering. now WHY would CMG do this?? i find that now even when the CMG is just barely tight enough to make a contact, it is all the way bright, basically no more dimming.

I would guess the black coating is there to protect the contact from wear and oxidation, since it's used as a switch contact- The stuff definitely adds contact resistance, though, I figure about at least 10-15 ohms or so. I didn't want to scrape it away just yet though- Brave soul!

Heck, I'm willing to do just about anything to improve a $10 light. No worries there. I'll give all the suggestions a try when I next have use of all my limbs (I have a baby sleeping on my currently).

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by DestructiveLight:
I have just (Right now!) scraped off the black covering. it has taken away the dimming effect! the contact pad is made of copper when the black is removed. the black stuff seems to be a semiconductive covering! as someone posted previously, when the resistance is measured on the black pad, it increases as the distance increases, same thing that happens when you try it on pencil lead. this leads me to believe it is a semiconductive covering. now WHY would CMG do this?? i find that now even when the CMG is just barely tight enough to make a contact, it is all the way bright, basically no more dimming.<HR></BLOCKQUOTE>

I don't know that I'd call it semiconductive, since a semiconductor permits current flow in one direction but not the other. It could though, be a density specific resistance material. If made of a carbon or graphite type material it's resistance would be variable depending on the density change created by the pressure on it. It's reason other than variable resistance could be as a protective coating, inhibiting oxidation.

CMG has been and still is very innovative and original in their offerings. They may not be very vocal about what they're up to, but if their past is any indication, they're going to lead rather than follow.

Maybe you can try scraping away the contact button as Destructive Light said, and solder a tiny wire loop in the center, to serve as a new contact surface- that should be a sort of "renewable" contact if it wears down.
Turbocharge your Infinity!