Surefire A2 findings (long)

[paulr]

I think you'd need fancy electronics, not just a thread adapter or two stage E2 tailcap. Remember that the L4 has a boost regulator. Putting resistance between the batteries and the regulator could confuse the circuit pretty badly. You need a separate circuit for low output, something like what the L1 has.

That's a good point about the A2 reflector losing some light. It makes me a little more interested in the A2.

 

[CM]

[ QUOTE ]
paulr said:
I think you'd need fancy electronics, not just a thread adapter or two stage E2 tailcap. ..

[/ QUOTE ]

Not really, read my post above. "I tried a 10 ohm resistor to close the circuit..."

It does work. Put enough resistance in there and you'll starve the regulator. It will reduce it's output to the LED accordingly. Nothing magic about that technique since that's what the L1 uses. There is only one LED in the L1 and the regulator in there is just a "dumb" regulator just like the L4.

CM

 

[McGizmo]

CM,

Seems like you have described the fabeled L2. /ubbthreads/images/graemlins/grin.gif I'd bet there are protos of just about all you have imagined sitting in a certain fellows office. Purely idle speculation........... carry on.

- Don

 

[CM]

Doh! Is that what an L2 is? I really need to come out of my cage once in a while. /ubbthreads/images/graemlins/grin.gif So the L2 is really along the lines of Unobtanium, then?

CM

 

[Klaus]

Chris,

I think a two stage tailcap for the E2e might be possible using the Z57 clickies - but I´m not sure if a 5W run at low curents wouldn´t get off-color then without a PWM.

If you disassemble a Z57 you´ll see that two little "legs" are making the contacts inside. For "trials" and partly by accident I was bending one of them a little and therefore got the two of those legs making contact after each other and not simultaneously as it should be. Now if one could/would modify the leg making contact first with some added resistance this would possibly results in a hobyist level two stage switch ?

Just an idea ...

Klaus

 

[CM]

Klaus,

The L4 with 10 ohms as described above didn't get off color at all. In fact, I'm wondering what this "underdrive and get green" hoopla is all about. I have not seen it yet. The mantra may be "overdrive and get rid of green" and *not* "underdrive and get green". The L4 using my "low" technique looks like an opalec newbeam on steroids. It's dimmer than normal, but still plenty bright, maybe too bright for a low beam setting. The resistor value will dictate how dim it is.

About the Z57, that sounds worthy of investigation. The resistor must be fairly large since it has to handle an appreciable amount of power. Maybe 1/8W. I tried to get my clickie apart but the d**n thing seems to be welded shut. Klaus, is it possible for you to post a picture of the Z57 taken apart?

CM

 

[kakster]

From my very limited experience with 5 watters, they do not suffer from colour shift nearly as bad as the 1 watt parts. When my 5 watt McLux drops out of regulation, it doesnt change colour, it just gets dimmer. My 1 watt R2H assumes a definate green tinge under the same comditions.

 

[Ray_of_Light]

I put a 47 ohm resistor in series with the batteries, and my L4 is drawing 70 mA, making a very usable light beam with no change in color.
The efficinecy is very low, indeed: the voltage drop across the resistor is 3.2 volt, it means that half of the used power is lost.
This approach is not beneficial, unless the regulator "knows" it has to switch to a lower power mode.

Anthony

 

[chamenos]

it seems only the green-tinted luxeons suffer a more drastic colour change. i had an arc LS that had a slightly green tinted led, which became very green once it dropped out of regulation. the current LS i have has a Q4J luxeon which has a blue/violet tint, and it just gets dimmer when out of regulation.

 

[CM]

Anthony,

I just did that measurement using 27 ohms and getting 100mA. You're right, it's wasted power. The L1 does the same thing, it dumps the power into the resistor. Surefire probably figures that with 3.5watt-hours per 123, they could afford to dump power into the resistor in the L1. The A2 also dumps power into the resistor since the 3 LED's draw about 110 mA by themselves. That's more than half the power lost. The regulator in the A2 is not designed to conserve power when using the LEDs. So a 47 ohm resistor in the L4 is actually not that bad relative to the A2. Take 70mA into 7 watt hours and you get 100 hours theoretically on low. That's a tradeoff I'm willing to make.

CM

 

[paulr]

CM, I missed your description of your 10 ohm resistor experiment at first. It's interesting. So, maybe there's some hope of adapting an L1 tailcap. Another solution is an electronic switch like the Arc LS4's, but that's probably not feasible for most modders to make themselves.

 

[CM]

paulr,

nukiez actually modified a Kroll with an Atmel microcontroller. I was impressed, but I want something the average CPF'er with the right tools can do himself, just like you mentioned. I also wired up the L4 using the 2-stage switch as-is and got about 1/3 brightness on the low setting. That's just a resistor value change. The results were good enough that I now want my L4 to be dimmable. This topic seems to be morphing from the A2 to the L4. I guess switches are applicable to both.

CM

 

[Klaus]

Working on it -- I`ll upate this ASAP -- grrr - the one part not as nice with the Ixus (Digital Elph) is the macro functions for close up shots /ubbthreads/images/graemlins/frown.gif I´ll post what I have in a second and will try to make better ones then - Shelby-San to the rescue /ubbthreads/images/graemlins/smile.gif

 

[CM]

Klaus, you're da man!

CM

 

[Klaus]

Lets try those

I´ll update with better details RSN

Good enough ?

 

[Klaus]

Another possible approach might be to "fill up" the area before the "legs" bent inwards (looking like a sloped capital L) with something sticky to the metal which transmits current but with some resistance - the level of "dimmness" one wants to achieve would be determined by the amount of "something" - maybe something similat to that black stuff on the original Inifinities ? That way some current would flow with slight pressing of the clickie´in an area whch before didn´t made contact - the area making contact now wouldn´t needed to get touched. Maybe some tricky fiddling required - any idea what could be applied ?

Klaus

 

[CM]

Klaus, nice shots! Good enough? You bet. Those two tabs look like they're common electrically? If so one can be made to engage before the other. Works theoretically. Now I gotta get mine apart to try it out to see if it's viable /ubbthreads/images/graemlins/grin.gif

CM

 

[Klaus]

Yes - they are connected - I´ll email you on something else in a minute

All the best

Klaus

 

[CM]

Klaus, I got mine open! Wow is it tight in there. I think it's gonna be some work to do this mod. I need to think about this one, Surefire did not waste any space in there. It's also a pretty intricate mechanism that looks almost fragile. The A2 2 stage must be fairly complex as well. Wouldn't be surprised if the A2 had more piece parts than my Glock pistol /ubbthreads/images/graemlins/grin.gif

CM

 

[paulr]

CM, re the 10 ohm resistor in the L4, did you measure the voltage across it during operation (preferably with a scope because of the PWM regulator)? I wonder how much power got dissipated in the resistor. It might be quite a bit. The best way to dim a LED is to PWM it. I wonder if that's a feasible mod for an L4.