The SF A2 - Part 2

js

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This space reserved.

I will be doing a 2nd part to the first installment of my The SF A2 thread. So I am posting this now because the 1st part is getting up towards 250 posts, well over the 200 post suggested maximum size for a thread.

Continued discussion should continue here, not in part 1.

Thanks!

And again, I will be editing this post to fill it up with lots of good SF A2 technical details--but not for some time. Still, I am going to do it eventually. Just as a teaser, I plan on posting oscilloscope pictures of the LVR in action.
 

JNewell

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One good topic for this continuation thread might be the "low incan" mode (snip from your concluding post on the Part 1 thread below). I think some people would assume that the regulation circuit would boost low battery voltage to the normal level for the incan bulb and then quit completely, rather than permitting the incan bulb to operate at sub-regulation voltage. Another related topic would be whether operation at that level has any operating effect on bulb life.

Also, please note that I just edited the first post as I realized that in the discussion of exactly what is happening during the occurance of an "low incan" mode, I left out the fact that low batteries can cause this and not just extra resistance in the contacts. In fact, I see this every time my batteries get to the point where they will no longer support the incan. The incan doesn't just totally stop. Instead I push to activate it, and get a 1/3 or 1/4 power incan beam, and it has always been fixed by installing new batteries. And I left this possibility out of account in my original discussion. DUH! Too obvious or something.
 

js

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JNewell,

The LVR is a PWM buck only regulator. It can only cut down on the DC equivalent voltage, not increase it. This is why the regulator is 99 percent efficient.

The "dim incan" mode won't hurt the bulb in any way--and besides, it doesn't last for long anyway before the batteries no longer even turn on the regulator at all.

As I said before, the "dim incan" mode occurs because the regulator has a turn-on voltage setpoint, and a lower turn-off voltage set-point. So in certain situations the power source and circuit path can be such that it can turn on the LVR, but not KEEP it on. In that case, you get a ON-OFF-ON-OFF, etc. modulation on top of the usual operation of the regulator.

It's just inherent in the way the dual-mode operation is set up for the A2. Just like how the LED's are on when the incan is on. Some consider this a defect, and perhaps it is, but the fact remains that it would require a TOTAL REDESIGN of all elements of the A2 in order to "fix" this, or the "low incan" mode. These are what they are, but to my mind, they are pretty minor issues, if they are "issues" at all. I don't mind the LED's being on when the incan is on, and if I had to choose, I would choose a regulation scheme where you have some kind of warning before totally losing your high beam.

Anyway, start to think about how a dual mode light could be implemented. Wrack your brain for all the different ways and how you would make it work, and you will see--I think--that the A2 occupies one of the optimal solutions for doing a multi-level light. The other one is, I think, a uC. But in that case, you have a more complicated user interface than the A2 switching operation.
 

buihia

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hmm a question on the A2 LED..

may i know if the LED mode of the A2 will be as bright as the keychain light that Lighthound ships free for every 20 dollar purchase..will it be brighter or dimmer than that ?
 

joema

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buihia said:
...if the LED mode of the A2 will be as bright as the keychain light that Lighthound ships free for every 20 dollar purchase..will it be brighter or dimmer than that ?
One "Photon II clone" tested by FLR had an overall output of 1.2: http://www.flashlightreviews.com/reviews/amart_kph.htm, by comparison an Arc AAA-P had an overall output of 5.2: http://www.flashlightreviews.com/reviews/arc_aaa-p.htm, and the Surfire A2 LED mode (white) also had an overall output of 5.2: http://www.flashlightreviews.com/reviews/surefire_a2.htm.

I have all three of those lights, and the Photon II clone is not as bright as the Arc AAA-P or A2, and the beam is narrower. Keep in mind overall output is a function of both brightness and surface area of the beam at a given distance. Only a little wider beam angle at the same distance translates to a lot more surface area (area = pi * r^2), hence at the same surface brightness a lot more output.

However unlike the FLR test, my A2 LED mode appears somewhat brighter than my Arc AAA-P, especially considering the broader beam. Not hugely so but somewhat.
 

EV_007

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buihia said:
hmm a question on the A2 LED..

may i know if the LED mode of the A2 will be as bright as the keychain light that Lighthound ships free for every 20 dollar purchase..will it be brighter or dimmer than that ?


The freebie keychain is way brighter and whiter than the white LEDs of the A2, HOWEVER, the LED on the keychain light is overdriven and the runtime on the included batteries will be a fraction of the A2's LEDs.

That little keychain rocks! I've given many away to friends and family.
 

JimmyB

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OK, speaking of A2's, anyone notice different beam characteristics on the newer A2's? I have an older A2 with red LED's that I bought right after they came on the market. It has the typical A2 oblong, "football" shaped beam, and is a pretty good thrower.


I just bought a round body A2 (white LED) that has a very round beam, none of the artifacts of the original, and in fact looks very much like an E2E beam (MNO3). The entire beam is very smooth all the way to the edges. It appears to be much more of a flood style although it still reaches out pretty well. Is this an anomaly or have the lights or lamps changed. I'd just swap lamps from the old to new just to test them but I don't have access to my old A2 right now.


I actually prefer the way my new A2's beam looks/works so if it is a fluke, I'm keepin it
icon4.gif
 

Blindasabat

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I have a newer round style body and I have a football beam, but mine is not that new and I don't have an old one to compare to. I do have a new spare lamp, but it's still in sealed packaging, so I never tried it. Let us know how your lamp swap works out. I may have to open my new lamp now...
JimmyB said:
OK, speaking of A2's, anyone notice different beam characteristics on the newer A2's? I have an older A2 with red LED's that I bought right after they came on the market. It has the typical A2 oblong, "football" shaped beam, and is a pretty good thrower.

I just bought a round body A2 (white LED) that has a very round beam, none of the artifacts of the original, and in fact looks very much like an E2E beam (MNO3). The entire beam is very smooth all the way to the edges. It appears to be much more of a flood style although it still reaches out pretty well. Is this an anomaly or have the lights or lamps changed. I'd just swap lamps from the old to new just to test them but I don't have access to my old A2 right now.
 

js

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My guess would be that it is a fluke, and actually is due to the collar on the lamp assembly itself. In other words, if you filed away some of the collar to allow the lamp to protrude into the A2 head a bit more, you might find the beam becoming more oblong.

Or, you can always add some kind of spacer to the collar to effectively pull the lamp back a bit. I would use kapton tape for this, but whatever it is, it should be heat resistant and should stay on the collar and not fall off inside the top of the body/head area and gunk any thing up (or short it out).
 

MacTech

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I'm a relative newcomer to the A2 crowd as well, and i've gone through all the standard phases of A2 ownership;

1; New-Toy-itis; "This is the COOLEST flashlight EVAR!!!!11one!" ;)
2; Second Thoughts; "wait a minute, what does the A2 do specifically that makes it *worth* $150-200?, my <insert flashlight #1> and <insert flashlight #2> do the same things as the A2 and are *less expensive* to boot...."
3; Regret; "this thing was a waste of money, maybe I should *sell* it?..."
4; Usage; "well, if I'm thinking of selling it anyway, maybe I should actually *USE* it for a bit first, see if I really want to sell it and take a loss, or just chalk it up to a learning experience..."
5; Understanding; "I finally *GET IT*, the A2 *IS* an awesome light, it's a perfectly *balanced* illumination tool, low LED puts out just the *right* amount of light for most general use, and the high-beam has a nice balance between flood, throw, and color rendition, it may not be the brightest SureFire, or the longest running, but it's *just right* for 90% of most flashlight needs, it really is a stellar light
and finally....
6; Satisfaction; "Now that I have, use, and understand my A2, I have no "need" to buy any more flashlights, if I get the urge for a new light, I simply look at my A2, ask myself 'what will it do that my A2 won't?', and 90% of the time, the desire for the new light simply vanishes...."

Basically to make a long post longer ;) , the A2 is a rare light, it's something you need to spend *time* with actually *using*, not White Wall Hunting, actually *using* it, if you try to evaluate the A2 on a short-term basis, you'll likely not "get" it, and come away unsatisfied, give it at least 3 weeks to a month of actual *use* before passing judgement on it, it's meant to be a "balanced" light, it's not blisteringly bright like a P61 equipped SF, it's not an ultra-long runner (although the LED's *ARE* pretty darned efficient), and the beam pattern isn't the flawless SF beam pattern so beloved of WWH'ers, it *is* what it *is*, the *perfect*, balanced EDC for those that actually *use* their lights as tools

Now that i've spent a good amount of time maligning and generally badmouthing the A2, but in a good way ;), let me cover it's *good* points, and there are many;

It's the perfect length for EDC, it fits my hand perfectly, the body disappears into my palm, the tail-cap sticks out far enough for comfortable use of the momentary/twisty one-handed, the bezel sticks out far enough from my hand to give an unobstructed beam, by comparison, when holding my G2 and 6P, the bezel of the light is partially hidden by my hand, the knurling on the A2 has the right balance of grippability without being too aggressive, the 6P's knurling is a little smoother, and the G2's checkering is smoother still

The incan is remarkably efficient, i've been using the light pretty much constantly for the past few weeks incan burn-times typically range from momentary to 10-15 minutes at a stretch, i've lost count of the amount of time i've used the LED low-beam, and after all of that, the incan beam is just as bright and white as the day I took it out of the packaging, the batteries ZTS at 60% even after a bunch of heavy use, the regulation circuit, documented so admirably in JS's A2 "Überthread" does a remarkable job of keeping the incan beam bright and white throughout the battery life, I was skeptical, to say the least, of all the vaunted performance numbers of the regulated incan, but they're true, the regulated incan works, is reliable, and is a brilliant bit of engineering

The low-beam LED's on paper are *laughable*, 3 lumens, an artifacty yellow/blue beam, typical of Nichia 5MM's, it's no WWH winner (although the incan beam does throw a kinda' cool "Biohazard"-y beam pattern), but you know what?, in *real life* use, it doesn't matter, the 3 lumen LED beam is in the form of a wide, soft flood with a slightly brighter hotspot, but it clearly leans more towards the floody side than throw, that 3 lumen flood does incredibly well with dark adapted eyes, and is quite usable rooting around in dark computer cases as well, the wide flood is far more usable than you'd think, and the color balance of the Nichias aren't too bad for general use either, and of course, being LED's efficiency is a given, i've been able to take batteries that ZTS at 0% and get usable light out of them with the A2's LED beam

This is my first SureFire with Hard Anodizing, and it's holding up remarkably well, yes there are tiny spots on the "points" of the knurling that are starting to get silvery, but that's expected as HA doesn't adhere well to "edges", it's going to happen with use, and it's less than 1% of the light in total, the other 99% of the light looks as good as the day it came out of the packaging, I even like the slight color mismatch on the bezel ring, bezel and body of the light, gives it a more functional, more stark, "military" look

This is also the first SureFire I don't feel comfortable letting the Unenlightened use, yes part of it is the fact it's a $200 flashlight and I don't think my cow-orkers would treat it with the respect due an expensive tool, but the other part is the fact that it's just such a cool light, and I know for a fact that my cow-orkers wouldn't truly be able to appreciate [Gollum] The Precioussss [/Gollum] the way I would, that's okay, I have a P61'ed 6P and G&P 3W LED'ed G2 that I can hand out as loaners, that is when I don't have my MagLed 3AA on me

If you're willing to give the A2 a chance, not just a quick test, give it an actual *chance*, I think you'll be pleasantly surprised
 

Atomic_Chicken

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Greetings!

JS - I just read through the entire 8-page original thread you started, as well as this one. I just wanted to say "Well Done" to you... thanks for such an informative article and for starting such a great set of replies.

I personally don't think the A2 is for everyone - but I'm quite certain that it is for me! :)

P.S. Love your avatar!

Best wishes,
Bawko
 

cslinger

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You its pretty funny to me that the A2, which is a comparitively old flashlight for this community, is still one of the "cool" useful lights that folks tend to eventually come to. That fact is, it is one of the best most balanced lighting tools I have ever seen. If you are simply looking for the coolest toy or brightest toy or best beam on a wall the A2 is not for you. If you are looking for one of the best lighting "tools" to be used as a "tool" then the A2 is hard to beat.

Chris
 

clipse

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Dangit, now I'm thinking I need to get an A2 again. I really miss mine and wish hadn't have sold it.
 

cslinger

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A2 was a great light...a few years ago

What lighting needs today can the A2 not do vs. a few years ago? Personally I still don't think there is a light on the market that can match the A2s versatility and usefullness. I am predominently a LED kind of guy but a good incan. is still a better tool for several purposes and the A2 just does everything so well.
 
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