I have found it-Duo bulb

[Cody JW]

I have just found what I have been looking for.A bulb for the spot side of the duo to sit next to the 14 LED unit that is brighter than the 120 Lumen apex and seems as bright as the Fennix HP-10. The spot is narrow compared to the fennix but is bright white and compares to the fennix.This gives you the best of both worlds, the perfect "throw" of the 14 LED bulb and the spot of the fennix both inside the housing of what I think is the best cave light ( time tested, sorry sten) the duo.This has a heat sink built in with the bulb so you can use this in a plastic light.The HP-10 is nice but has tunnel vision and does not light up your feet like I think it should but has an awesome spot.The duo 14 lights up around your feet like a carbide but does not have a spot that compares to modern LEDs, problem is now solved with this bulb, you have both, glow and spot.So far this is just one of two made so far as someone on this forum gave me one to try.I hope he can market this.I was shocked when I turned it on and compared it to my 120 Lumen apex and the fennix HP-10.I am going to take the fennix off my ecrin and go back to the duo, a light I used for 14 years with no problem, just upgraded bulbs.I had to take the reflector out so this unit will fit but once I got it in ,all I can say is WOW- finally a duo that compares favorable to modern lights.

[kmstill]

I'd be interested in hearing more - can we get any pics? Is your buddy considering making more?
Kelly

[Scott McCrea]

[Chads93GT]

What i wonder is how efficient it is. What I like about the fenix is how bright it is, and how it will run for 7 hours unlike the apex which goes unregulated after 1.5 hours on high.

[Cody JW]

What i wonder is how efficient it is. What I like about the fenix is how bright it is, and how it will run for 7 hours unlike the apex which goes unregulated after 1.5 hours on high.

Chad I am told six hours, not as good as the fennix but close, much better than the run time on an apex (what is not?)What I like about this is you can still fit the spare bulbs in the head and can replace bulbs in the cave, try that with an apex, sten or fennix.I have the 8 and 14 LED insert and use the 14 but can carry the 8 in my pack as a spare.I also have a spare LED spot bulb, brighter than the halogen that comes with the duo but not near as bright as this bulb.Love the duo, and with this bulb I can hang with todays commercial lights AND service it in the cave without needing a degree in electronics.

[potholer]

Fitted, the unit looks like:

(though yellow/blue wires now switched to all-yellow for cosmetic reasons.)

Regulation is rock-solid until the batteries are pretty much flat - I had a ~6hr10 run on 4x full 2000mAh Eneloops, and the output current on the test unit was 362mA dead, right up to the point the batteries were pretty flat (around 1V/cell).
At the end of that test, the LED was starting to flicker. I had to turn off and leave for an hour to do other things, but when I then tried the cells with a 14LED unit, they seemed to run it OK. Presumably the 14LED would have been less bright if run immediately after the test terminated, but I imagine would still have been usable for long enough to do a battery change somewhere convenient.

The graph below is from that test.
I just checked another 4 units with part-used Eneloops, and they were all pulling 270mA+/-4mA, but I don't know how part-used the cells were - they've mainly been used for brief blips of testing, so could be pretty full. It's probably better to think of 280-290mA as the typical draw from 4xNiMH.
I could get fractionally more driver efficiency, but I chose to add a little bit of bypass to the driver, which means the light would still work (at a reserve power setting) even if the driver failed. It's 'costing' maybe 20mA, so about 7% of power/runtime.
That bypass is kind-of removable, but thinking about it, it would be easy to make it easier to remove, so if it turns out that the drivers really are rock-solid, a tech-happy user could just snip it off. I just have a thing about having redundancy where possible, even in a dual-beam light. The driver should be pretty reliable, since it's being run well under its maximum rating, and I haven't had any using the same chip fail in other similar applications.

There's reverse-voltage protection in the driver, in case of reversed batteries or fitting to older Duos with variable battery polarity.


On the graph, the input current was only measured to the nearest 10mA, which is why it looks flat even as the input voltage falls.
I'll probably do an alkaline test soon-ish, and will wire my better current meter on the input, since it seems like it's rather redundant on the output.

[Scott McCrea]

Where can we I get one?

[Chads93GT]

heh, that optic looks like a stock piece out of an apex............... ie, black plastic "back reflector" and a solid clear plastic slug with a dimple in it, just like that photo, to regulate the throw.

Did you mention what kind of bulb that is yet? because I dont see it.

[Cody JW]

heh, that optic looks like a stock piece out of an apex............... ie, black plastic "back reflector" and a solid clear plastic slug with a dimple in it, just like that photo, to regulate the throw.

Did you mention what kind of bulb that is yet? because I dont see it.

Chad- I ran this up next to the new apex and it was not even close,the apex had a wide spot-wider than the fennix or this.But this bad boy was bright white compared to the apex, the difference was shocking.It was close to the fennix.I know several people out there had the duo and then could not wait to replace it with an apex or maybe the big money sten but I knew that sooner or later ,with so many LED bulbs out there and so many smart people out there ( all the techie cavers) that someone would come out with a bulb like this, the duo is too good of a light and easy to interchange bulbs for this not to happen.Not to mention all that were sold over the years.I held on to mine waiting for this to happen.I already had the duo and did not want to " throw the baby out with the bathwater" and knew all I had to do was purchase a screw base upgrade,I was lucky for potholer to choose me to try this.I hated to take the duo off the ecrin to put on a "better"new light.Well guess what, the "better" new light is comming right off and into my pack as a spare and the duo is going right back on- where it belongs.

[Chads93GT]

Heh what i meant was, what kind of actual LED bulb is used in it. The optic is what looks like its out of a stock apex. I only say that because i modded about 8 of the apex's around here with updated p4's and new optics for better throw. The stock pieces that came out were what i described above and look just like those. How much is a new duo? ive only seen 1 in person, if that gives you an idea on how popular they are with everyone i have caved with, lol.

[Cody JW]

I would be willing to bet money that there are more duos sold in the world (lots outside of USA included) than any cave light in my 30 years of buying lights.

[Cody JW]

Keep in mind, caving is a "niche" obscure sport in The USA,in Europe where Petzl is made it is more mainstream,just like most Americans think the ropewalker is the most used climbing system-not halfway close to the frog worldwide

[potholer]

heh, that optic looks like a stock piece out of an apex............... ie, black plastic "back reflector" and a solid clear plastic slug with a dimple in it, just like that photo, to regulate the throw.

Did you mention what kind of bulb that is yet? because I dont see it.

So far, I've used Q5 Cree XR-Es.
R2 bin often seem harder to get in nice colour bins, and would only be fractionally more efficient. That said, the order I just put in, they did have R2s of the right colour, and they were only fractionally more expensive, so I got those instead, but I'm not sure if it's worth the effort of telling anyone - it'd be like having quarter-pound burgers and 4.25 ounce ones, and making a big deal out of it.

The optic choice largely dictated the LED model choice.
The ones I used give a good tight beam with at least some usable spill (much more than the LED bulb replacements I've seen), and also fit in the available space, which many other similar-sized optics wouldn't, from the viewpoint of depth or of rear diameter (or both).

For a less-tight beam, there could be possibilities with an R5 XP-G, but I've only got a few XP-G optics to try out so far, and the tightest one would have rather less throw. Given the nature of the XP-G, I doubt whether any XP-G+optic combination that would fit would be likely to give a beam as tight as the one I've currently got.
However, I'm open to suggestions at to how tight is too tight for various people.

I just got a decent digital camera with proper manual mode, so I should be able to do some more objective comparisons of LEDs and optics than I could previously.
Unfortunately, those would just be LED+optic shots - I don't have any of the typical US caving headtorches to do comparison shots with.

[potholer]

How much is a new duo? ive only seen 1 in person, if that gives you an idea on how popular they are with everyone i have caved with, lol.

I think lights often have a fairly 'lumpy' distribution.
Even before I surrounded myself with a pretty good local monoculture by making [a different model of] lights for most people in the various clubs I cave with, I didn't personally see many Duos around over here with people I knew, generally only a subset of carbide users who bought their units when Duos were the default electric backup.

However, when going out of my way to cave with other groups, whether being at a loose end and just turning up randomly at the roadhead for a popular large system, or when joining/helping groups that happened to be staying at my [main] club's accommodation, I've often found groups that were largely Duo users.

That said, over here there really isn't much use of Apexes, etc, maybe at least partly down to the poor pricing (UK £ price close to US $ price even when exchange rate is close to £1==$2), and various other historic reasons, so the Duo does generally have a pretty good share of the market in its particular price range.

[Scott McCrea]

The Duo 14 may not be the brightest or longest burning headlight out there, but it is, hands down, the best value at ~$130. Its reliability and durability is top notch. If you can't trust a light in a cave, what good is it? Add a super-bright spot, like this, and it gets even better. And, you can change the batteries without taking your helmet off.