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Thread: Low voltage LED options for the FM C-cell “C” bodies w/ SF KT-2 TH **More Beamshots**

  1. #31

    Default Re: Low voltage LED options for the FM C-cell “C” bodies w/ SF KT-2 TH **More Beamsho

    Quote Originally Posted by Kestrel View Post
    Something like twice the lux perhaps, I can’t recall the numbers you had? That was one of the goals for this – a great thrower with the advantage of high efficiency and long runtimes.
    I think that's right. I'll have to find the numbers.

    Quote Originally Posted by Kestrel View Post
    Hmm… JC evaluated the 2xC system and concluded that he couldn’t boost the current enough to satisfactorily drive an MC-E, but maybe there are some options with 3xC…
    I think we had been looking at how to drive a 2S2P MC-E at full power, which can't be done using 2xC NiMH. You'd need about 6.6V * 1.4A = 9.24W of power delivered to the LED. With 2xC at say 2.4V and a generous 90% board efficiency, that means 4.3A of input current from the batteries to the driver. A 14mm driver, which is what fits in these AW Turbo Towers, will not like 4+ amps of input current. Plus, the BBNG can't boost up to 6.6V anyway (Wayne's spec says 6V max for Vout).

    Now, you could underdrive the MC-E, wiring it in 4P (turning it into a pseudo P7). I don't think we explored that. I like underdriving the P7 more and more since you can still get a lot of lumens out of the emitter with a low forward current (say 250mA or 350mA) and low associated forward voltage.

    I don't like building AW towers using MC-Es though. The fit is very tight and I sweat it out every time I grind the MC-E's case to fit the emitter through the SureFire TH reflector opening. Maybe I'll give it a shot (I have an extra K-bin MC-E) and run it in the FM 3xC body with a GD1000. The negative is that you aren't going to get the throw that you'd get with a single die emitter. The benefit, at least for a K-bin MC-E, is somewhat more lumens out (maybe 20%) with greater LED efficiency (lower Vf). If I had an M-bin, then maybe I could get 30%-40% more lumens.
    Last edited by Justin Case; 05-18-2009 at 01:53 PM.

  2. #32

    Default Re: Low voltage LED options for the FM C-cell “C” bodies w/ SF KT-2 TH **More Beamsho

    Quote Originally Posted by Kestrel View Post
    I am currently doing a runtime test on 2xC alkaline, but without a lightmeter, I’ll just have to use my best guess on when a decline in output occurs.
    If you have a Canon camera, the free firmware CHDK provides a poorman's light meter function.

  3. #33
    Moderator Kestrel's Avatar
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    Default Re: Low voltage LED options for the FM C-cell “C” bodies w/ SF KT-2 TH **More Beamsho

    Update: runtime test.
    Note: lumen outputs are estimates, done by comparisons to other regulated LED flashlights of relatively-known output.

    Runtime for the P4 / BBNG / 2xC alkaline:
    ~200 lumens for ~3 hours
    6 total hours to ~30 lumens
    11 total hours to ~15 lumens (test termination)

    At this point, I could still make out the hotspot at night on a tree over 100 feet away, albeit it was a pretty dim spot at that range.

    Runtime for the Malkoff M30 w/ 2xC alkaline:
    ~130 lumens for ~3 1/4 hours
    6 total hours to ~15 lumens (test termination)

    So things are in the output - runtime department. I expect that the difference might be even more dramatic with 3xC where the BBNG driver may not have to run the cells at maximum to get the full 240 lumens, and that the M30 would be running at a higher wattage condition. Remember, if the cells have less drain, not only do they last longer for the same watt - hours, but the effective watt-hours in the cell actually increase at lower drain rates - this has been measured by SilverFox and demonstrated by JS in his SureFire M6 X-LOLA thread:
    http://www.candlepowerforums.com/vb/...77#post2900877

    I'm actually inclined to not do a runtime test for the 3xC configuration. Too much hassle, and having to make judgement calls on output drops with the gradually declining alkaline chemistry gets a bit annoying. In addition, I don't really intend on the 3xC being actively used in this configuration anyway.

    Quote Originally Posted by Justin Case View Post
    Maybe I'll [run the MC-E] in the FM 3xC body with a GD1000. The negative is that you aren't going to get the throw that you'd get with a single die emitter. The benefit, at least for a K-bin MC-E, is somewhat more lumens out (maybe 20%) with greater LED efficiency (lower Vf). If I had an M-bin, then maybe I could get 30%-40% more lumens.
    From your lumen calculations & lux measurements, I recall that you were approximately doubling the overall lumens with the MC-E compared to your P4 in a SF Turbohead, but halving the maximum measured lux. Losing all that throw makes for a completely different light, and for me the SF Turbohead is all about throw.
    Quote Originally Posted by Justin Case View Post
    If you have a Canon camera, the free firmware CHDK provides a poorman's light meter function.
    Wow, that's an amazing piece of software, I am using a Canon point-and-shoot that this should work on. A lot to digest... mmm... brain swelling...
    Last edited by Kestrel; 05-19-2009 at 08:49 PM. Reason: Runtime test information.
    In the past we have had a light which flickered, in the present we have a light which flames, and in the future there will be a light which shines over all the land and sea.
    - Winston Churchill

  4. #34

    Default Re: Low voltage LED options for the FM C-cell “C” bodies w/ SF KT-2 TH **More Beamsho

    Quote Originally Posted by Kestrel View Post
    From your lumen calculations & lux measurements, I recall that you were approximately doubling the overall lumens with the MC-E compared to your P4 in a SF Turbohead, but halving the maximum measured lux. Losing all that throw makes for a completely different light, and for me the SF Turbohead is all about throw.

    Wow, that's an amazing piece of software, I am using a Canon point-and-shoot that this should work on. A lot to digest... mmm... brain swelling...
    IIRC, those calculations were for a 2S2P MC-E, which would get 500mA per core from an SOB1000. In 4P, each core gets only 250mA (very underdriven) from the boost-buck GD1000.

    You are right on the hot spot lux. The bigger multi-die of the MC-E (and similarly, the P7) just doesn't focus as tightly as a single die emitter for the same reflector. When driving the MC-E at higher drive currents, however, you do get a lot of light. The spill can be impressively bright and ceiling bounce starts to look like you turned on a ceiling light fixture.

    Yeah, CHDK is pretty amazing.
    Last edited by Justin Case; 05-18-2009 at 06:08 PM.

  5. #35

    Default Re: Low voltage LED options for the FM C-cell “C” bodies w/ SF KT-2 TH **More Beamsho

    As a surrogate for underdriving a 4P MC-E at 250mA per core in an AW tower using an SOB1000, I checked my 4C Mag mod that uses a DxxxI-bin SSC P7 driven by an SOB1000. I measured 3.07V for the forward voltage and 0.84A at the Mag tail when using 4xC Energizer alkalines. Daekar's emitter flux Excel spreadsheet estimates over 300 emitter lumens, assuming 250mA per core.

    Based on this, I am tempted to build a 4P MC-E AW Turbo Tower for a KT1/KT2 TH and install it on my 3C FiveMega SureFire C head body. I broke down and ordered some Accupower C NiMH LSD cells. I'd probably use a GD1000 driver from the Shoppe.
    Last edited by Justin Case; 05-22-2009 at 09:29 AM.

  6. #36

    Default Re: Low voltage LED options for the FM C-cell “C” bodies w/ SF KT-2 TH **More Beamsho

    That should be superb! Can't wait to see how it throws.


  7. #37

    Default Re: Low voltage LED options for the FM C-cell “C” bodies w/ SF KT-2 TH **More Beamsho

    I would imagine that it will throw the same as my MC-E/AW Turbo Towers using an SOB1000 and installed on a regular SF 12ZM. Like all of these big, multi-die LEDs, the MC-E doesn't focus as tightly as a single-die LED. The MC-E still has a bright hot spot, though. Just not as bright as something like an SSC P4 U2-bin. But with the increased total lumens, you really get a lot of light in total. So when you hit a room using ceiling bounce, for example, the entire room lights up. My main reason for building such a tower is the ability to use an MC-E based AW Turbo Tower in a low voltage application (in-line with the topic of this thread) -- 3xNiMH. And with the low Vf, I should get that much better run time. i doubt I'd get a Vf that low with an SSC P4 at 1000mA drive current. I also have several towers using the SOB buck driver, so they all run at higher voltages -- 2xLi-ion, etc. Nothing for the low voltage case.

  8. #38

    Default Re: Low voltage LED options for the FM C-cell “C” bodies w/ SF KT-2 TH **More Beamsho

    I had a random thought this morning. Incans seem to excel at generating light to the side. Reflectors bounce this 360 degree sideways light forward and you get throw. LEDs are generally configured face forward, so less of their light goes to the side and less of it hits the reflector, reducing throw. Quad emitters exaggerate this and even less goes to the side, even less throw.

    I wonder what would happen if a central emitter were surrounded by 4-5 others arranged in a circle facing out, at the reflector. Would this mimic incan bulbs enough to create the same kind of throw?

  9. #39
    Moderator Kestrel's Avatar
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    Default Re: Low voltage LED options for the FM C-cell “C” bodies w/ SF KT-2 TH **More Beamsho

    Quote Originally Posted by ElectronGuru View Post
    I had a random thought this morning. Incans seem to excel at generating light to the side. Reflectors bounce this 360 degree sideways light forward and you get throw. LEDs are generally configured face forward, so less of their light goes to the side and less of it hits the reflector, reducing throw. Quad emitters exaggerate this and even less goes to the side, even less throw.

    I wonder what would happen if a central emitter were surrounded by 4-5 others arranged in a circle facing out, at the reflector. Would this mimic incan bulbs enough to create the same kind of throw?
    The problem with that configuration is that it becomes a very large light source, defeating the parabolic shape in the SF TH which best focuses a single point source.

    Looking closely at my P4 (no , so I'm seeing spots as I type this), it seems to do a really good job sending light out pretty evenly from the axial center to the edge of the LED. IIRC many incan bulbs are frosted etc at the tip to reduce the artifacts coming straight out from the filament & potentially-non uniform glass envelope i.e. no OP reflector to even those photons out. I once had a close look at an OLD SureFire L1 (pre-LuxeonIII, LuxI perhaps?), and it had a funky prism-looking configuration just above the actual diode which would appear to send light exclusively to the sides. Interesting.

    JC, I'm looking forward to seeing your FM3xC/MC-E/LSDNiMH configuration, especially beamshot comparisons between the P4 in a SF TH if possible. IMO my 3xC is just too much length for what additional performance it gives me over the 2xC, and I can't justify NiMH for a light I rarely use w/ free Alkaline C's. MC-E/P7 might change the equation though.
    Last edited by Kestrel; 05-22-2009 at 12:43 PM.
    In the past we have had a light which flickered, in the present we have a light which flames, and in the future there will be a light which shines over all the land and sea.
    - Winston Churchill

  10. #40

    Default Re: Low voltage LED options for the FM C-cell “C” bodies w/ SF KT-2 TH **More Beamsho

    I'll post photos and beamshots when completed. I'd prefer a P7, but it is too big to fit through a SF TH reflector opening, unless I did surgery on the TH. An MC-E barely fits, and only after you grind away some of the corners of the LED case and fiddle with the leads that stick out. The clearance is minimal, so all wiring and soldering has to be tidy with no excess space consumed.

  11. #41

    Default Re: Low voltage LED options for the FM C-cell “C” bodies w/ SF KT-2 TH **More Beamsho

    So as not to excessively hijack Kestrel's thread, I will just mention that I finally built the 4P K-bin MC-E AW tower using a GD1000 boost-buck driver (250mA per core), all installed in a KT1/2 TH on top of a FiveMega 3xC body. Power supplied by 3xAccupower LSD NiMH cells, total resting voltage of about 4.03V.

    Got a tailcap draw of 0.865A, hot spot lux of 4700 lux, and midpoint spill lux of 130 lux. Swapping the tower into an SRTH, I got 5000 and 130 lux. In comparison, a 2S2P K-bin MC-E AW tower driven by an SOB1000 buck driver (500mA per core) in a KT4 TH measured 6500 lux and 230 lux, respectively for hot spot and midpoint spill. The same tower in an SRTH measured 7400 and 220 lux. A tower with an SSC P4 U2SWOH-bin instead of a K-bin MC-E in an SRTH measured 13000 and 70 lux.

    I'll post construction details and beam shots later in the Homemade and Modified Lights forum.

  12. #42

    Default Re: Low voltage LED options for the FM C-cell “C” bodies w/ SF KT-2 TH **More Beamsho

    Great thread..

    M30 on 3xC does look a little brighter than M60...

    As I said, I run M30 on 3xAA and at first, the alks are pretty bright but diminish quickly. Of course it rocks on 3xAA L91 Lithiums.

  13. #43
    Moderator Kestrel's Avatar
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    Default Re: Low voltage LED options for the FM C-cell “C” bodies w/ SF KT-2 TH **More Beamsho

    Quote Originally Posted by etc View Post
    Great thread..

    M30 on 3xC does look a little brighter than M60...
    Thanks for the .

    re: the M30/3xC in this thread appears brighter than the M60/2x17500.
    I know, I've been wondering about that exact observation in the 'underexposed' beamshots for quite some time now. Besides the possibility of an underachieving M60 (an older model that I have photos of here (the one on the top): http://www.candlepowerforums.com/vb/...2&postcount=18 ) or an overachieving M30, my other guess is as follows: The tint of my M60 is on the warm side, while this particular M30 is rather cool. Perhaps it might be a tint artifact that photographs differently in beamshots? (I'm only using a point&shoot Canon - set to manual - which tries to outwit me if I'm not paying attention.) Needless to say, I am not able to differentiate the brightness between the two Malkoffs visibly, but the photos suggest differently, as you've observed.

    At any rate, the M60 I am using for a standard in this thread is a beautiful thing during actual use, the best of the five Malkoffs I've seen.

    Edit: I know that the optics are different, but the older M60's supposedly have an optic that provides a smaller hotspot with possibly higher lux. Geez, I don't know... Your opinion on the hotspot size in the pics?
    Last edited by Kestrel; 06-15-2009 at 05:47 PM. Reason: Different optics between the two?
    In the past we have had a light which flickered, in the present we have a light which flames, and in the future there will be a light which shines over all the land and sea.
    - Winston Churchill

  14. #44
    Moderator Kestrel's Avatar
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    Default Re: Low voltage LED options for the FM C-cell “C” bodies w/ SF KT-2 TH **More Beamsho

    Quote Originally Posted by etc View Post
    As I said, I run M30 on 3xAA and at first, the alks are pretty bright but diminish quickly. Of course it rocks on 3xAA L91 Lithiums.
    I've been trying to pursuade a machinist friend of mine to make a 4xC body for his (used to be my) M30. It should be ~280 lumens at that voltage (as measured by MrG on a benchtop power supply). It would also make for a great baton.
    In the past we have had a light which flickered, in the present we have a light which flames, and in the future there will be a light which shines over all the land and sea.
    - Winston Churchill

  15. #45

    Default Re: Low voltage LED options for the FM C-cell “C” bodies w/ SF KT-2 TH **More Beamsho

    Quote Originally Posted by Kestrel View Post
    I've been trying to pursuade a machinist friend of mine to make a 4xC body for his (used to be my) M30.
    How about cannibalizing a Mag 4C tube? Then all he has to make is a M30 -> Mag tube adapter.

  16. #46

    Default Re: Low voltage LED options for the FM C-cell “C” bodies w/ SF KT-2 TH **More Beamsho

    That's a good idea, but I suppose it might also depend on whether you like a tailcap button or a side button.

  17. #47
    Moderator Kestrel's Avatar
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    Default Re: Low voltage LED options for the FM C-cell “C” bodies w/ SF KT-2 TH **More Beamsho

    Quote Originally Posted by ElectronGuru View Post
    How about cannibalizing a Mag 4C tube? Then all he has to make is a M30 -> Mag tube adapter.
    The thing I really like about these FM bodies is that they take a P-series bezel so well, and that the threads on the head & tailcap are really nice, much better than the tailcap threads on those other bodies.

    Edit: You know, thinking about an FM 4xC and then looking at 26650's like in this new thread (3.7v nominal, 4000 mAh LiMn), http://www.candlepowerforums.com/vb/...d.php?t=232520
    What would things be like with an FM 4xC body, three of the above would fit perfectly in a body of that length. There was much gnashing of teeth when the 3300 mAh LiIons left, 3x26650 has approximately the same watt-hours as 4xC(LiIon), but in a safe chemistry. If you could live with the length of a 4xC host, this would provide ~45 watt-hours vs ~20 watt-hours from 4xC alkaline.

    Now if someone had a FM 2xC that, when cut down, could fit one of those 26650's (diameter still could be the issue), that would make a great single-cell host and would blow away the AW IMR26500, providing 80% more runtime over the single 26500 for only 15 mm more body length. It would also provide ~40% more runtime than 2xC alkaline, and would be 35 mm shorter.

    Ahh, the advantages of high voltage that I've eschewed for this build...
    Last edited by Kestrel; 06-17-2009 at 05:08 PM.
    In the past we have had a light which flickered, in the present we have a light which flames, and in the future there will be a light which shines over all the land and sea.
    - Winston Churchill

  18. #48

    Default Re: Low voltage LED options for the FM C-cell “C” bodies w/ SF KT-2 TH **More Beamsho

    Here is a size comparison of a 2C and 3C FM vs a 2C Maglite:

  19. #49
    Moderator Kestrel's Avatar
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    Default Re: Low voltage LED options for the FM C-cell “C” bodies w/ SF KT-2 TH **More Beamsho

    Quote Originally Posted by Justin Case View Post
    Here is a size comparison of a 2C and 3C FM vs a 2C Maglite:
    That's a very nice comparison pic, thank you.
    In the past we have had a light which flickered, in the present we have a light which flames, and in the future there will be a light which shines over all the land and sea.
    - Winston Churchill

  20. #50

    Default Re: Low voltage LED options for the FM C-cell “C” bodies w/ SF KT-2 TH **More Beamsho

    Bump from the past, but was just wondering if there have been any more developments in this area.
    I am a big fan of the 2 cell format and these FM bodies are sweet.
    How does a M31 fare in the 2 C body.

    On a similar note I have been experimenting with similar dimension lights. I picked up a FM Megallenium 26500 x 2 and a custom module for Lumens Factory Seraph P7 TH. The driver is the same 3 mode that LF run in their 4.2v modules. The led is still a P7 with that beautiful creamy neutral tint LF have.
    A great mod for what I wanted. Obviously not a thrower like the high voltage P7 module but it puts out as much light or more as a similarly driven xpg.

    I have been thinking about an MD10 with an M31 driver for a normal M3 bezel. I have a spare bezel lying around and it looks good on the FM body.

  21. #51
    Moderator Kestrel's Avatar
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    Default Re: Low voltage LED options for the FM C-cell “C” bodies w/ SF KT-2 TH **More Beamsho

    Hey there Rat6P.

    Quote Originally Posted by Rat6P View Post
    Bump from the past, but was just wondering if there have been any more developments in this area.
    I am a big fan of the 2 cell format and these FM bodies are sweet. How does a M31 fare in the 2 C body.
    Probably pretty well - I really like the M31 since it is considerably better than the M30 in a number of respects. The thing is that I eventually sold off these setups of mine since I wanted to get away from the 'C' form factor - 18650's and Eneloop AA's are really nice and have gotten the bulk of engineering improvements by various manufacturers. I do agree that these FiveMega bodies seem to be extraordinarily well-made, the only bodies I've seen (personally) that were considerably nicer than any of my SureFire hosts.

    Edit: Looking back at those beamshots, I do miss that throw a little; I don't have anything that does that quite so well ...
    Last edited by Kestrel; 03-03-2012 at 09:42 AM.
    In the past we have had a light which flickered, in the present we have a light which flames, and in the future there will be a light which shines over all the land and sea.
    - Winston Churchill

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