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Thread: Replacement of carbide lamps by LED lamps

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    Flashaholic Tobias Bossert's Avatar
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    Default Replacement of carbide lamps by LED lamps

    Replacement of cavers carbide lamp by LED lamps

    1.Purpose of this treat
    2.Development of a headlamp optimized for caving
    3.Amount of light required
    4.Color temperature and beam pattern
    5.Batteries and electronics
    6.Optics and housing

    1.Purpose of this treat

    Candlepowerforums is substantial work, sometimes too extensive to find exactly what you need. The purpose of this treat is to bring together all those information required to develop an optimized headlamp for utilization in caves.

    I start this treat with a lot of additional information and hope, that I can learn from feedback and proposals the members of Candlepowerforums can give me.

    I’m member of a cavers club in Austria. We plan to build our own headlamps for our club but not to sell them: we have NO commercial interest. But we think the ‘high tech’ products from www.lupine.de and www.scurion.ch are much too expensive for hobby cavers, so one aim is to develop cheep but never the less optimized alternatives.

    2.Development of a headlamp optimized for caving

    When I started my first expedition into a big alpine cave in 1965 I used a carbide hand lamp, as usual at that time. In those days it was impossible to achieve sufficient light output with battery flashlights for expeditions of several days. In the early 1970s cavers changed to carbide headlamps. Up to now most cavers still use carbide lamps, since these are extremely reliable, easy to maintain and provide sufficient light even for large rooms in big caves. Duration of expedition doesn’t matter, its a question of amount of carbide you take along (about 400g per day).

    Since some years, many manufacturers provide battery headlamps based on white LED. Unfortunately none of them really comply with what is required during a several days cave expedition. But indeed the technology is advanced enough to develop a headlamp satisfying these requirements.

    3.Amount of light output required

    The old lamps e.g. combine up to 250g of carbide with about 140g of water to produce an amount of 100g acetylene (~ 100 liters). Four sizes of burners are used commonly, consuming 7, 10, 14 or 21 l/h of acetylene. The flame delivers about 67, 92, 133 or 200 lm at a color temperature of about 2300K. The burner alone would throw a nearly isotropic pattern, only downwards a cone of about 60 degree is shaded by the burner itself. The burner is mounted in front of the helmet and uses a small reflector. During normal use, this reflector gets blackened quickly, so about 60% of the light can be used only. Most cavers in Europe use burners with 14 or 21 l/h providing a total luminous flux of about 80 to 120 lm. These lamps consume about 33 to 50 g/h of carbide. But the carbide lamp itself has an overall weight (carbide/water-container plus tube plus head lamp) of another 1000 g too.

    It would be nice to get the same total luminous flux from the new technique too.

    Actual white LEDs are promoted to deliver 100 lm/W. That’s not true. The following table demonstrates the achievable luminous output of four actual types off SSC P4.


    Table 1 – Achievable luminous output with actual white SSC P4 LEDs

    The electrical power required to replace the good old carbide lamp depends. Carbide lamps deliver a rather uniform spatial pattern, thus you have to compare with bare LED covered by plain glass only. In the worst case using the S_42182_S_SS0_I to replace a burner with 21l/h you will need 3,2 W drawn from the battery and in the best case using the W_42182_U_SVN_I to replace a burner with 14 l/h you will need 1,3W.

    So ‘paulr’ http://www.candlepowerforums.com/vb/...79&postcount=2 was right with his estimations!

    First thought: take SSC U bins, they are brightest! Really?

    4.Color temperature and spatial pattern

    We are not interested in the physiological sensation looking directly into the light source but rather in the amount of light being reflected from the objects we want to see. SSC U bin covers equivalent temperatures from 4500 to 7000K, quite different from our used carbide flame having 2300K. The reflection factor of typical materials found in caves depends on wavelength. Bluish materials are rare, e.g. loam is rather beige. Therefore it might be possible, that the “bright” U bins with 6700K subjectively will be less bright inside a cave than an objectively less bright S2 bin with 3000K.

    Color temperature

    First I tested those five LED types given in table 1 at home. Against a pure white wall indeed all U bins are the brightest subjectively. Against a wall colored with ‘apricot white’ the S bin with 4000K subjectively seems to be at least as bright as the best U bin, in this case 5300K. Against a pine wood ceiling, the S2 bin with 3000K appears brightest.

    Studies are carried out in alpine caves at the moment to determine the subjectively brightest LED type amongst those of table one. The tests cover both, plain LED (uniform spatial pattern) and narrow beam (10 deg), because it is not determined in advance, that the findings will be the same. I will supplement the results when finished!

    >> Questions to everyone:
    Are there better LEDs out for 3000 to 4000K than SSC P4 bin S and S2?
    Where can I buy W_42182_U_SUN_.. or ...SUM..., that’s 4500 to 5000K and nevertheless U bin?

    Spatial pattern

    The carbide lamp didn’t allow realizing a narrow beam. This is one significant improvement using LED technique, now you can look down into deep pits too. But during walking and climbing inside a cave, you rather would prefer uniform spatial pattern than any beam. Everyone who ever tried to make a night walk with a beam lamp knows what I mean: You either risk stumbling or you will get a stiff neck! Therefore the new electric headlamp should provide both, all-round light (covering hemisphere in front of you) and spotlight (as narrow as achievable), switched alternatively.

    5.Batteries and electronics

    In October 2007 I started the project and asked the members of candlepowerforums for applicable converter boards for my project. But this was on the wrong forum I think (flashlight electronics – batteries included). Now I can demonstrate three practical solutions, cheep, efficient and optimized for cavers headlamps. But the optimum solution depends upon the battery type to be used.

    Batteries

    Professional ‘high tech’ headlamps use Li-Ion rechargeable batteries. This is the best solution technically: Li-Ion provide the highest energy density (more than twice of alkaline and Ni-MH) and are able to deliver high drain currents even at low temperatures. But the problem arises from cavers negligence: They use the lamp until it gets dark and after the trip all the stuff ends up in the cellar, neither being cleaned nor recharged – this normally will be made up for 15 minutes before starting to the next expedition. Therefore I decided not to propose them to use Li-Ion rechargeable batteries.

    The second-best solution would be Li-FeS2 primary batteries. But if you start remembering your stuff just some hours in front of leaving to the trip and have not enough batteries at home, you will fail, because there is no shop providing these strange batteries on the way to the cave.

    Alkaline batteries would be the most practical solution in my mind. They are extremely cheep and available everywhere. But the characteristic of alkaline cells depends strongly upon the cell size! As you can derive from the studies of ‘Silver Fox’ http://www.candlepowerforums.com/vb/...ad.php?t=64660 the realistically achievable energy density of alkaline cells drained with low to medium currents is nearly independent of the cell size (50 to 90 Wh/kg depending on brand). This doesn’t surprise because the chemistry is the same for small and large cells. But the realistically achievable power per weight is much higher with smaller cells (AA-size above 20 W/kg but D-size below 8 W/kg only). Thus it makes more sense to use 6 AA cells than 1 D cells having the same weight.

    The achievable energy depends upon the power drained: the heavier the load, the smaller the drainable energy content. I made two tests in my household refrigerator: two battery packs (6 AA and 8 AA in series) were discharged with 1,5 W continuously down to 3,5V. This means, the first pack is loaded by 0,25 W and discharged to 0,6 V each cell and the second pack by 0,188 W and to 0,45 V. The weight of the second pack is 133% of first one, but delivers 142% of total energy. My conclusion is that these additional two cells could be carried much more comfortable in the backpack than in battery belt at the helmet or worn in the chest pocket!

    At the end I decided to propose using batteries of AA size. Most cavers I know will use alkaline types which you can purchase at every supermarket. But the electronics will also accept Li-FeS2 primary and Ni-MH rechargeable batteries of AA size too.

    As estimated above, at least 1,3 W will be required continuously to get an equivalent luminous flax as a carbide lamp. Inside alpine caves temperatures are about 0 to 6°C. Under such circumstances alkaline AA cells deliver about 1,5 to 2,2 Wh when drained with less than 250 mW continuously and if the converter board allows to unload the cells completely. Rough estimation: average cell consumption will be 0,7 to 1 cell per hour when using at least 6 cells in a battery pack. For a 9 hours trip with continuous light you will waste 6 ‘good’ or 9 ‘cheep’ AA alkaline batteries. The consumption expressed in weight is about 18 to 25 g/h. Remember: this will replace 33 to 50 g/h of carbide consumption, a reduction of 50%! And the device itself is much lighter than the carbide lamp too. Additionally we can hope LED efficiency still will increase in future ...

    Electronics

    We need thee levels of output current:
    Working light, about 350 mA, used continuously all over the day
    Pause light, below 35 mA, used during breaks
    Spot light, amara (as much as realistically achievable) used only for short term

    First I tested some of those multi mode buck converter boards from Kaidomain and DealExtreme. But I came back to the single mode types, because these are more flexible for my own modifications. At the end three boards are shortlisted: Taskled CC1W, Kaidomain sku.2982 and Dealextreme sku.3256. All three easily can be modified to match the requirements of cavers headlamps.

    Taskled CC1W

    By far this is the best board tested, but also the most expensive too ($15 + shipping). It has excellent manufacturing quality and George gives extensive support, answering your questions spontaneously! This board also provides the best efficiency. The output current can be varied by paralleling resistors to R2 or R3 labeled on the board.

    I provide you with measured curves for three modes, each of them with shortened polarity protection diode:
    Blue – original board (no resistors in parallel) => I = 350 mA, average efficiency 88%
    Green – dimmed down with R2 || 560 ohm => 35 mA, average efficiency 72%
    Red – boosted with R3 || 180 kohm => up to 620 mA, average efficiency 87%


    Figure 1 – Characteristics of Taskled CC1W

    Original and dimmed current is regulated constant. Boosted current would calculate to 670 mA, but the internal current limiter supersedes and the output current depends upon supply voltage. This is no disadvantage because it makes no sense to demand a boosted current from nearly discharged alkaline batteries. This board accepts supply voltages up to 20V.

    Kaidomain sku.2982

    This medium priced board ($ 3,10, free shipping) also has a good manufacturing quality but its efficiency suffers at higher current levels. This board accepts supply voltages up to 18V. Fortunately this board is now available again.

    Originally the board delivers 750 mA, always o.k. for our boost mode. To reduce output current you will have to unsolder pin 8 (FB) of the integrated circuit PT4105 and insert a resistor (I took 1,8 kohm). With an additional resistor of 56 kohm from FB to LED+ you will get about 350 mA output current, and with about 25 kohm (depends upon Vf of LED) you achieve 35 mA.


    Figure 2 – Characteristics of Kaidomain sku.2982


    Figure 3 – Application of Kaidomain sku.2982 for cavers headlamp


    DealExtreme sku.3256

    This low priced board ($ 1,61, free shipping) has poor manufacturing quality only but its efficiency is good. This board is specified for 1 A output current, but the current is unregulated and depends upon supply voltage and Vf of LED.

    Before you start modifying the output current of this board, you should solder ceramic SMD capacitors in parallel to these strange aluminium electrolytic capacitors, this will increase the efficiency by about 3% (I tried 2,2 or 4,7µF 16V).

    To reduce output current you will have to unsolder pin 4 (ISENSE) of the integrated circuit C300 and insert a resistor. This resistor should range below 100 ohm, because it is in the rf path (I took 39 ohm SMD type and soldered it on empty place “R2” after having cut the lower connection of it to IN-).

    With an additional resistor from ISENSE to ground (IN-) you can divide the sensed voltage and thus increase the output current. With an additional resistor from ISENSE to supply voltage (IN+) you can decrease the output current. But the effect of this manipulation depends upon supply voltage and therefore rotates the output current curve over input voltage clockwise. If you connect the resistor to LED- instead, this rotation will be even stronger. Choosing the optimum relation between resistors to IN- and to IN+ or LED- you can achieve a nearly flat response.

    With resistors of 27 kohm from ISENSE to LED- and of 220 ohm to IN- you will get about 1 A output current almost constant over an input voltage from 4 to 9V.


    Figure 4 – Characteristics of DealExtreme sku.3256 for high current level

    The current spikes in these curves occur when the device transfers from direct mode to switching mode and vice versa. The arrows show the different dynamic behavior for increasing and decreasing supply voltage. The arrows would be vertical with zero source impedance and horizontal with a pure current supply. During use with alkaline batteries you will not encounter these peaks, because the impedance of nearly discharged batteries is too high.

    1 A is not of interest for our project since we require lower currents. It is impossible to decrease the output current much below 100 mA using the original current measurement resistor of 0,020 ohms. You need to unsolder it and replace it by a higher value (I used 0,150 ohm). With this you can achieve flattened curve at 350 mA and 35 mA as demonstrated in the application. In this application the boost level intentionally is not flattened.


    Figure 5 – Application of DealExtreme sku.3265 for cavers headlamp


    Figure 6 – Characteristics of DealExtreme sku.3256 used for cavers headlamp

    The disadvantage of this board is the limited input voltage. Therefore the battery pack is limited to 6 alkaline cells in series or to 7 Ni-MH.

    6.Optics and housing

    Mechanical manufacturing seems to provide more problems than electronics!

    Optics

    Most actual white LED provide a dome with a week spatial concentrating. This is fine for working and pause light and needs no additional optics which would cost 15 to 25% of light anyhow. But at least you will need a plane of glass to protect the LED and the starboard. Even this will cost about 10% of emitted light and restrict the spatial pattern to about 150° (original is 180°). It would be preferable to use a transparent spherical cap, comparable to http://www.khatod.eu/pdf/pljt20_test_report.pdf but not opalescent.

    >> Questions to everyone:
    Where can I buy such transparent caps?

    For spot light we need a reflector or lens optic with low losses, narrow beam and low stray light around the spot. Most of all miniature plastic optics don’t comply with this. The best results so far were achieved with Gaggione LL3 http://www.lednlight.com/LL3.htm, in German forums sometimes called ‘Mobdar’ but as far as I can see, these are from different sources. Unfortunately this collimator needs small modification to allow optimum placement of SSC P4 LED.

    >> Questions to everyone:
    Is there any better optics for SSC P4 LED on the market?

    Housing

    The headlamp mounted at the helmet contains two parts, one for spot light and another one for working light. Spotlight will be similar to http://default.nueb.de/fahrrad/licht/mueller/ but with smaller heat sink. The other one may be a short aluminium tube (diameter 25 mm) covered by a plane of glass at front side and by a small heat sink in the back.

    At the moment four arrangements are under discussion:


    Figure 7 – Four alternative arrangements of battery box and headlamp

    Arrangement a)
    Electronics, both switches and spot light mounted in the battery box; headlamp contains all-round light only; minimum weight and size mounted at helmet.
    Headlamp diameter 25mm, length 15 mm
    Cable with two wires only
    Battery box in the chest pocket 140 x 60 x 20/25 mm; spot light with diameter 40 mm protruding 5 mm out of the flat side; switches and cable outlet flush mounted at the smallest side
    Problem: How to protect spot during crawling?

    Arrangement b)
    Electronics and both switches mounted in the battery box; headlamp contains all-round light and spot light; all switches still safe in the pocket; spot light follows movement of head.
    Headlamp diameter 25mm, length 25 mm plus diameter 40mm, length 25.
    Cable with three wires.
    Battery box in the chest pocket 120 x 60 x 20 mm; both switches and cable outlet flush mounted at the smallest side; alternatively one rotary switch instead of two toggle switches.

    Arrangement c)
    Electronics and only main switch mounted in the battery box; headlamp contains all-round light, spot light and switch to choosing amongst all-round and spot light.
    Headlamp diameter 25mm, length 25 mm plus diameter 40mm, length 25.
    Cable with three wires.
    Battery box in the chest pocket 120 x 60 x 20 mm; main switch (work-off-pause) and cable outlet flush mounted at the smallest side.

    Arrangement d)
    Only batteries in the battery box; headlamp contains all-round light, spot light, electronics and both switches.
    Headlamp diameter 25mm, length 25 mm plus diameter 40mm, length 25 plus diameter 25mm, length 25 mm (containing electronics).
    Cable with two wires only.
    Battery box in the chest pocket 100 x 60 x 20 mm; if desired, battery could be changed together with battery box.

    In any case the battery box is required to be solid enough to accept the barer rests on it at a stony subgrade. The headlamp is required to be solid enough to accept knocking one’s head against the roof. Both parts are required to be waterproof.

    At the moment nothing mechanical is realized; I’m happy not to be the one having to develop this!
    Last edited by Tobias Bossert; 08-19-2009 at 10:03 PM. Reason: we have NO commercial interests - not 'now'! Thank you FriBo for the hint.

  2. #2
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    Default Re: Replacement of carbide lamps by LED lamps

    Hello Tobias,

    Welcome to CPF.

    This looks like quite a project...

    If I may comment on your selection of batteries.

    In the conditions you are going to be using the light, the optimum, in my opinion, power supply to use would be the CR123 primary lithium battery. I don't know how many are in your club, but you could put in a bulk order and have ample cells to power your light.

    I would suggest you explore using 2 of the CR123 cells in series. Back up power could be supplied by a 9 volt battery, if your circuit would allow that, and you could also utilize a 4 AA battery holder for those who like to carry extra weight... or for the use of the Energizer L91 battery.

    Alkaline AA cells work well in the 5 - 10 C temperature range, but it has been my experience that once the temperature drops below 5 C, you need to make provisions to warm your batteries, including your spares.

    Good luck on your project.

    Tom
    Behind every Great man there's always a woman rolling her eyes...

    Most batteries don't die - they are tortured to near death, then murdered...

  3. #3
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    Default Re: Replacement of carbide lamps by LED lamps

    your pictures are over the size limit
    Light is the activity of what is transparent - Aristotle

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    Default

    please, first of all !!!
    make the pics smaller, so that one does not have to scroll sideways to read that whole post
    (I came to 2/3 till got bored and only answer to that parts)



    several points to consider:
    * try to find the TINT of the led You like, not the BIN, thats of prime importance.
    * forget the Seouls and use Crees
    * being picky on normal prices for circuits (15,-- being expensive ) is no use for Your applications.
    * I have seen carbides in caves - there will never be a more appealing short distance area light
    (possibly try sunny white 5mm leds for this)
    * working light @ 350 mA - thats the power my headlamp runs on --> for running and biking. WAY too powerful and unnecessary for normal caveing use imho

    the best TINT-showing tread on CPF: http://www.candlepowerforums.com/vb/...d.php?t=156772


    wenn Euch das interessiert (because Austrian cavers club), kann ich Euch ja mal ein paar meiner gemoddeten Lämpchen zeigen, damit Ihr nen Eindruck bekommt - wenn Ihr Euch in Wiennähe trefft (befinde mich selbst in Baden),
    oder kommt mal zu einem Nightride (gepostet auf bikeboard.at)
    Last edited by yellow; 01-05-2008 at 11:59 AM.

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    Default

    phuaa, now got the whole post - good luck on the project, it sure has arleady given You quite some thoughts, right?

    I read all the usual bad things (what I consider as bad) where ppl make themselves unnecesary probs and new ones with every problem solved (starts with wanting to produce ones own light head, ...)
    Better find Yourself a flashlight that can do what You want except of runtime, then use just its head and make someting to connect the batts with it.
    Or find a cheap light You like from its looks on DX (You know the site already), put the led You like inside, circuit behind, add end plate and method of mounting to housing, connect to batt pack --> ready, including a nice housing, front glass, rubber O-rings, ..., with less work a homemade housing will give


    the part I can totally not understand is how the lights, possibly the whole equipment, is cared and prepared for after and before the uses. Anyway, there is Li-Ion only for You, a pack made from 4 pc. of 18650 will cover at least 20 hours of the 350 mAh draw.
    read more here
    (I would still mod it a bit, f.e. this protection circuit instead of that large Bratbeck, but ...

    or get a light that is meant for 2 pc. CR123a, use just its head and have it run with 7.2 V Camcorder batts - which should ease recharging as most ppl have one.

    ... You main problem will be that most light are aimed on brightness - I see no chance You can do with without modding something
    PS: did I already mention to use Crees instead of the blue Seouls?


    [edit]
    Question: how hard is that temperature problem? Thought cavers wear the batts strapped to the body under the outer clothing? Isnt that a higher temp then?
    Anyone of You uses the common Petzl led models or other commercial led headlamps? Do You all agree on to change to led? (even when only knowing the Petzls?) [/edit]
    Last edited by yellow; 01-05-2008 at 12:03 PM.

  6. #6
    Flashaholic Tobias Bossert's Avatar
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    Default Re: Replacement of carbide lamps by LED lamps

    Quote Originally Posted by yellow View Post
    PLEASE, FIRST OF ALL !!!
    make the pics smaller, so that one does not have to scroll sideways to read that whole post

    Uups!
    I sized the pics to 1200 pix maximum width. This works fine on a screen with 1280 pix width and with browser settings not consuming more than 80 pix on left and right.

    Now I have reduced the pics to a width of 950 pix, this should be visible completely even with a screen width of 1024!

    Please don't forget to empty your browsers cach befor reloading the page, because otherwise you will not see any difference.

    This is no good solution, that there is no autoscaling managing this: So all users have to restrict to the reader with the most narrow screen...

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    Flashaholic Tobias Bossert's Avatar
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    Default Re: Replacement of carbide lamps by LED lamps

    Quote Originally Posted by yellow View Post
    * working light @ 350 mA - thats the power my headlamp runs on --> for running and biking. WAY too powerful and unnecessary for normal caveing use imho

    Hi yellow,
    i'm used to caving since more than 40 years now! Let me say, there are many halls in caves where you blow water into your carbide lamp to increase the flame, but nevertheless it's still too week.
    But even with the normal pressure produced by the water in the tank above the carbide the lamp gives about 80 to 120 lumens all the time. To output 100 lumens from a LED lamp you need more than 350 mA at present, don't forget the losses in the headlamp (glass).
    In caves I frequently pass along tunnels more than 10 m broad, and you realy mean that 350 mA is WAY too powerfull? - It isn't!
    And last but not least: I'm used to have this amount of light in caves for many years and will not reduce my demands now.
    Kind regards
    Tobias

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    Default Re: Replacement of carbide lamps by LED lamps

    Quote Originally Posted by Tobias Bossert View Post
    Are there better LEDs out for 3000 to 4000K than SSC P4 bin S and S2?
    Here are warm white Q2-bin Cree leds that produce at least 87.4lm with 350mA
    http://www.led-tech.de/en/High-Power...64_120_77.html
    At that site you can also find Seoul and Lumileds leds. For maximum light output but with high color temperature i would recommend to use Q5 bin Cree XR-E leds instead of the Seoul leds.

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    Default Re: Replacement of carbide lamps by LED lamps

    Hello Tobias,

    I need to point out that the forum rules state that the maximum picture size is restricted to 800 X 800. You are close, but you need to shrink them down just a little more.

    Thanks.

    Tom
    Behind every Great man there's always a woman rolling her eyes...

    Most batteries don't die - they are tortured to near death, then murdered...

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    Flashaholic Tobias Bossert's Avatar
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    Default Re: Replacement of carbide lamps by LED lamps

    Quote Originally Posted by Jarzaa View Post
    Here are warm white Q2-bin Cree leds that produce at least 87.4lm with 350mA
    Thank you very much!
    Indeed this warm white Cree XRE WHT-L1 5C Q2 is really "warm" (5C = 3700 to 4000K) and much brighter (87 to 93lm @350ma) than everything from SSC in warm or natural white. I'll try them out immediately!
    The other LEDs XRE WHT-L1 WG Q5 you mentioned are too "cool" (WG = 5700 to 6200K), but you are right, they are brighter than the comparable SSC P4 with U luminance.
    I'm still looking for SSC USUM or USUN (4500 to 5000K), but may be your warm white Cree will be the winner!
    Kind regards
    Tobias

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    Default Re: Replacement of carbide lamps by LED lamps

    Quote Originally Posted by SilverFox View Post
    Hello Tobias,

    I need to point out that the forum rules state that the maximum picture size is restricted to 800 X 800. You are close, but you need to shrink them down just a little more.

    Thanks.

    Tom
    SilverFox,
    sorry, indeed I violated the forum rules.
    Now all pictures are max. 800 wide. Is it necessary to formerly reduce the size of some pictures, because the pictures containing two combined diargrams are still higher than 800 pixels?
    Please give me advice in case I should also reduce the hight of all these diagrams to 800 pixels.
    But in this case I should rearange the pictures because the photos and circuitdiagrams mounted into the measurement curves will no more be recognizable.
    Sorry for the trouble I make to you. I will learn and next time avoid such big pictures.
    Kind regards
    Tobias

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    Default Re: Replacement of carbide lamps by LED lamps

    Hello Tobias,

    There has been some discussion amongst the administration if we could make exceptions for graphs. However, this is still in discussion and as it stands right now, the rules state a maximum of 800 X 800.

    Thank you for your cooperation.

    Tom
    Behind every Great man there's always a woman rolling her eyes...

    Most batteries don't die - they are tortured to near death, then murdered...

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    Flashaholic Tobias Bossert's Avatar
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    Default Re: Replacement of carbide lamps by LED lamps

    Quote Originally Posted by SilverFox View Post
    Hello Tobias,
    There has been some discussion amongst the administration if we could make exceptions for graphs. However, this is still in discussion and as it stands right now, the rules state a maximum of 800 X 800.
    Thank you for your cooperation.
    Tom


    done now!

  14. #14
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    Default

    looks like we typed to different topics ...

    - for the "walk around use" the 350 mA for the headlamp is very bright,
    The mountain guide (which I asked to lead us because there were some 1st timers around) had his Aceto running and that 5 meter 360 degrees area light was just great. Dont think anything can make a similar nice light.
    for distance work it was useless (You know that already)
    - for looking at larger distances (better a handheld lamp application?), even my Cree @ 1 A seemed too dim (this summer while visiting the Frauenmauerhöhle), but it was by far the strongest light of the group.

    There is also some other thing that can be annoying, especially with Led-headlamps (compared to the Acetos): being more focused, one tends to blind the person to talk to. At 350 mA or above it will take a bit of time to see again.

    thus the best way is still, if You and Your caving buddies could test some lights inside a cave, possibly with different power levels.
    What if You do all the work, finish the 1st light and then noone likes the more focused beam? Or the other colored light?


    PS: I do understand that You dont want to switch to less light than now
    but how is it possible to compare "100 Lumen" at the Aceto with "100 Lumen" of a Led?
    1st light has no real beam, the other one lives just from its 8 deg. main beam.

    PPS: what kind of lights do You guys use now when You have to reach out far into the dark?
    Because I know no "normal" commercial headlamp that is good in this dept.
    Last edited by yellow; 01-06-2008 at 09:13 AM.

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    Flashaholic Tobias Bossert's Avatar
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    Default Re: Replacement of carbide lamps by LED lamps

    Quote Originally Posted by yellow View Post
    - for the "walk around use" the 350 mA for the headlamp is very bright,
    The mountain guide (which I asked to lead us because there were some 1st timers around) had his Aceto running and that 5 meter 360 degrees area light was just great. Dont think anything can make a similar nice light.
    o.k., now we are near by...
    Most of us use Petzl Aceto with 21l/h burner. You are right, this is a nice ligth, you can walk without needing to decline your head always downwards. It's known, the light output of Aceto is about 80 to 120lm. So it is realistically to achieve the same all-round light electrically. This is the task of my "work light". Indeed, I think we can make a similar nice LED light too!
    Fist tests with different LED headlamps on the market were negative, they cut the beam too narrow! There is one exeption of a verry good commercial headlamp, www.scurion.ch but much to expensive for us. They also use a separate bare LED without any optics as work light and provide additionally a second LED with a narrow beam optics too.

    Quote Originally Posted by yellow View Post
    for distance work it was useless (You know that already)
    - for looking at larger distances (better a handheld lamp application?), even my Cree @ 1 A seemed too dim (this summer while visiting the Frauenmauerhöhle), but it was by far the strongest light of the group.
    PPS: what kind of lights do You guys use now when You have to reach out far into the dark? Because I know no "normal" commercial headlamp that is good in this dept.
    Yes, this is the reason for the second LED with narrow beam optics. The LL3 from http://www.gaggione.it has a beam factor of 30 to 80 cd per lm, depending upon type of emitter. With a SSC P4 U luminance or a Cree XRE 7090 Q5 you will get about 5000 to 10000 cd (5 to 10 million mcd!) @ 700mA.
    At the moment, most of us use commercial halogen headlamps from Petzl for this, but far less strong. I use a self made 10W halogen headlamp with really narrow beam (you see it on my personal photo). The combination LL3 plus LED @ 700mA is still brighter...

    Quote Originally Posted by yellow View Post
    There is also some other thing that can be annoying, especially with Led-headlamps (compared to the Acetos): being more focused, one tends to blind the person to talk to. At 350 mA or above it will take a bit of time to see again.
    That's correct, the acetylene flame is much bigger than the dimension of the emitting area of a bare LED! This is indeed a disadvantage of using a bare emitter. I was thinking about using an optics with diffuser (very wide beam) this would solve this problem, but will cost some 15% of light at least!
    The best way out is yust not found jet...

    Quote Originally Posted by yellow View Post
    but how is it possible to compare "100 Lumen" at the Aceto with "100 Lumen" of a Led?1st light has no real beam, the other one lives just from its 8 deg. main beam.
    You can: The luminous flux of azetylene flames are known (in our case roughly about 100lm). The spatial pattern is nearly uniform. Color temperature is 2320K. So its possible to compare this directly with a bare SSC P4 with 3000K, also having a nearly uniform pattern. Our subjective tests with a selfmade testdevice in a cave some days ago showed, both light sources are comparable with one another!
    Naturally you can't compare subjectively a uniform with a narrow beam light.

    Now I also can provide you with first results of our color tests I anounced before.
    In the past I was convinced of loam and limeston in caves being beige or even reddish brown. That's still true, but not to that extend! This was rather an artefact of the reddish carbide lamps we used in caves. The tests showed, that warm white brings no real improvement over natual white and even onle a small one over pure white, at least for pure white with temperature below 6000K!
    But I will repeat this test again with the new Cree XRE 7090 5C Q2 (~4000K) and 87lm @350mA instead of 54lm.

    Next I will make a testdevice with different spatial pattern for work light. Bare SSC P4 is quite uniform but bare Cree XRE 7090 has a somewhat smaler pattern. This testdevice also will cover combinations of bare emitters and wide beams too. I will post results when available...

    At the end you will see: I do not make me problems which are still solved, as you posted earlier. I think there was nobody before, having solved these problems accurately before starting his design for a new headlamp, isn't it?

    Best regard
    Tobias

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    Flashaholic* uk_caver's Avatar
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    Default Re: Replacement of carbide lamps by LED lamps

    Having compared a Seoul running at a little under a Watt with a few carbide lights, it does certainly seem to be in the same ballpark, though it can't compete with a carbide in 'turbo mode'.

    A wide beam is certainly useful underground, and there is the group aspect of carbide users lighting up the cave all around them for other people to look at.

    However, when it comes to my light lighting up things for me to look at, from experience first with a 'naked' LED with a near 180 degree spread beam, and secondly with a more restricted spread beam, roughly in a 90 degree cone, I barely notice the loss of the extreme wide light, but I definitely appreciate the increase in light within the more limited area, and that seems to be a widely-shared opinion among people I know who've tried both options.

    Though I might be able to use some extreme-wide light in my peripheral vision, with an unmoving head I only have about a 60 degrees sideways range of stereoscopic vision, and a vertical range of about 90 degrees. A 90 degree cone tilted slightly downwards lights up almost anything I need to look at

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    last post in here, just to give an idea for testing ...

    However, when it comes to my light lighting up things for me to look at, from experience first with a 'naked' LED with a near 180 degree spread beam, and secondly with a more restricted spread beam, roughly in a 90 degree cone, I barely notice the loss of the extreme wide light, but I definitely appreciate the increase in light within the more limited area, and that seems to be a widely-shared opinion among people I know who've tried both options.
    I would go even further and say that a led, especially a Seoul of Lux, is totally useless without focusing device.
    Maybe that so-said tighter beam degree of a Cree, but ...
    and
    that 180 deg. led without focusing device disturbs Your opposite very much.
    --> as is commonly known, the smaller the light souce, the higher the glare (right word?).
    I'm just playing around with such a bare led (Seoul) and its totally annoying from anywhere I look at it.

    btw: I tested it with an Elly, modded with a Seoul and head removed
    and this light is why I do this post
    (as I do have the feeling You are not totally sure on what led, what focusing device and what degree to use. And without these, all the rest gives bad results, even when housing or circuits are an irreal 120 % effective).



    PS: the 1st beam pic is with the head screwn out a bit, the full wide beam would be even more

    When modded with the Seoul, the position of the led inside the Elly changes a bit.
    * When the head is screwn in fully, the Seoul is too deep inside the reflector and this leads to a very broad main beam - perfect for checking what I have here in the room, just a few meters away (= area light).
    * When screwn out a bit, its totally focused - much brighter but also very small hotspot
    * Head removed - totally useless area light that not even shows the pieces 2-3 meters away that are good to look at with the wide beam
    and makes me look away, no matter from where I look at the bare led.

    The other plus of this very cheap, very easy to mod Elly is, that one could remove the reflector inside very easy and insert just any optic/reflector, screw in the head and the front glass pushes against that part and holds it in place.
    That way, with getting a few different Led and different degree focusing devices, one can bring a light source along very easy and for cheap, to decide what is best and then use this in the real light.

    Heck, they are so cheap, one could even get a few and mod them differentially - not to have to change the delicate parts

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    Flashaholic Tobias Bossert's Avatar
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    Default Re: Replacement of carbide lamps by LED lamps

    Quote Originally Posted by uk_caver View Post
    However, when it comes to my light lighting up things for me to look at, from experience first with a 'naked' LED with a near 180 degree spread beam, and secondly with a more restricted spread beam, roughly in a 90 degree cone, I barely notice the loss of the extreme wide light, but I definitely appreciate the increase in light within the more limited area, and that seems to be a widely-shared opinion among people I know who've tried both options.
    Though I might be able to use some extreme-wide light in my peripheral vision, with an unmoving head I only have about a 60 degrees sideways range of stereoscopic vision, and a vertical range of about 90 degrees. A 90 degree cone tilted slightly downwards lights up almost anything I need to look at
    Thanks for your information. I got a similar feedback from some cavers in our club. My personal experience is, that it is more comfortable when standing still and looking into a room to have concentrated the light into a cone of about 60 to 90 degrees. All the other light around it is nearely not of interest, because you realize things only in this range. Say: the spill around this cone seems to be lost energy.
    But when you are walking over a rough surface, e.g. bolder stones, you need the spill touching your feet (or you have to incline your head up and down frequently to gather the information), otherwise you might stumble . It's interesting, you don't become aware of the things around your feet intentionally but nevertheless you need it.
    May be, we should look for a non concentrical beam pattern...
    I will put this problem on the back burner at the moment and call up again when finished the studies on required luminance in caves depending upon color temperature.

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    Flashaholic Tobias Bossert's Avatar
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    Default Re: Replacement of carbide lamps by LED lamps

    Quote Originally Posted by yellow View Post
    180 deg. led without focusing device disturbs Your opposite very much.
    You are right, that's why I posted my thoughts on using LED with optics and diffuser instead of bare emitter earlier: This increases the light emitting area tremendously. But it costs efficiency too...

    Thanks for the pictures of this versatile mod of Elly! But I have build my own test device with 10 switchable places for emitters/optics, so I'm able to test 10 different configurations at one cave trip.

    Quote Originally Posted by yellow View Post
    as I do have the feeling You are not totally sure on what led, what focusing device and what degree to use. And without these, all the rest gives bad results, even when housing or circuits are an irreal 120 % effective
    Yes, you are absolutly right! At the moment I do not know which LED and what kind of focussing device to use for working light. That's the reason why I make all these tests and experiments: finding out what I need!
    And that is one of the reasons why I posted this treat: To learn from everyones experience...

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    Default Re: Replacement of carbide lamps by LED lamps

    Quote Originally Posted by Tobias Bossert View Post
    But when you are walking over a rough surface, e.g. bolder stones, you need the spill touching your feet (or you have to incline your head up and down frequently to gather the information), otherwise you might stumble . It's interesting, you don't become aware of the things around your feet intentionally but nevertheless you need it.
    I'd guess that for normal walking, my eyes would be zoned on a point maybe 5 or 6 metres in front of me, with my head tilted accordingly.
    Additionally, I mount my light in a mining lamp headset, which (in conjunction with the helmet bracket) ends up with the lamp axis being tilted somewhat downwards relative to 'helmet horizontal' or 'head horizontal'.
    Finally, I don't usually need to look directly down, I only really need to see the place where my next steps are going to be, and that's a little way in front of me.
    The end result of those three factors is that a 90 degree (full-angle) cone seems to work OK most of the time without needing any obvious extra head-tilting.

    However, the other LED in my setup can also provide quite significant downlighting when it's on, and with uneven floors I'd tend to have that LED running at least at low power, since it's the one that provides distance lighting for route-spotting, so it's possible that there are times when my cone of wide light isn't quite wide enough on it's own that I don't notice.
    Last edited by uk_caver; 09-21-2008 at 03:45 AM. Reason: removing typo

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    build my own test device with 10 switchable places for emitters/optics, so I'm able to test 10 different configurations at one cave trip.
    wow,
    I bet You plan to make more than just one lamp - quite some efforts ...

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    Default Re: Replacement of carbide lamps by LED lamps

    Have you considered trying an Princeton Tec apex and replace the LED with a warmer emitter? The apex is rated to 1M water depth. They now have an exteme version with a remote battery 8AA pack, or you could use our own battery pack with any of the apex varients. The apex mod is easy and you can pick your tint of emitter to use. I love my modded apex.

    BTW, Princeton Tec has no info on the website regarding the apex extreme.

    http://www.brightguy.com/products/Pr...EX_Extreme.php

    6PD with DX Cree drop in *Awesome*, L2D Q5, TK11, PT APEX (My first mod with SSC P4-Thanks CPF!). EDC - FENIX LOD CE & P2 Q5.

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    Flashaholic Tobias Bossert's Avatar
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    Default Re: Replacement of carbide lamps by LED lamps

    Quote Originally Posted by yellow View Post
    wow,
    I bet You plan to make more than just one lamp - quite some efforts ...
    Yes, this is right, we plan to build our own headlamps for some members of our caving club.
    ***We definitly do not plan to sell those lamps***
    Quite the other way round: Any results - failure as well as found optimization - will be posted here. So we hope that some manufacturers will take some ideas from this discussion and develop a new headlamp or optimize an existing model. This would be very helpfull for us and othes too, because everyone can avoid building final lamps by hand!

    But up to now, I know only one really good commercial headlamp for caving (www.scurion.ch) - much too expensive! And even this one could be further improved with respect to color temperature and pattern of its bare emitter working light.
    There is no option at the moment to choose one model on the market and modify it with actual highly efficient LEDs.

    Last but not least: you should calculate neither the time spent to experiment with this things nor the money you spent to build your test-devices and pre-models, it's just our hobby! The efforts you mentioned, that is what enyoys!

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    Flashaholic* uk_caver's Avatar
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    Default Re: Replacement of carbide lamps by LED lamps

    Quote Originally Posted by Tobias Bossert View Post
    But up to now, I know only one really good commercial headlamp for caving (www.scurion.ch) - much too expensive! And even this one could be further improved with respect to color temperature and pattern of its bare emitter working light.
    I guess it depends what you mean by 'improve'.

    White LEDs can seem cold, but yellower ones aren't necessarily much better. In the days when I made luxeon-powered lights, and the LEDs I got weren't sold by colour bin, about half were 'proper' white, 30% yellowish, with the rest a little blue (apart from a couple with a purple tint).
    Going straight from using carbide, the yellowish ones maybe seemed a bit less cold than the white ones, but didn't seem quite as good for actually lighting things up, or for colour accuracy.
    Maybe for a wide beam, a red or amber LED could be added to the mix to give a more carbide-like light, but I'm not sure many people I know would go for that if it meant extra power consumption/loss of efficiency. It'd also be trickier to match in a focussed beam.
    Equally, though there can be initial comments when switching to a 'colder' light, that does seem largely to be a matter of adjustment.
    Commercially, tint doesn't seem to be much of a selling point, and I'd guess that minor complaints would generally be about something being too off-white in any direction (blue, yellow, red, or green).

    Also, 'improving' a wide beam is still a matter of taste. Though I'm happy with what I do regarding narrowing a wide beam somewhat, there are certainly people around here who really want a complete 180 degree spread.
    I haven't had any complaints about my approach, but given it was completely free and easily reversible, there wouldn't be much to complain about, and having 2-3x better forwards throw compared to a naked LED gave it a definite advantage.

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    Default Re: Replacement of carbide lamps by LED lamps

    Hi Tobias

    From my very limited caving experience, I would say arrangement D is the best option as it can be difficult to get your hands to your chest to operate light controls. And the controls would have to stand regular scraping along the ground without adjusting.
    You will have fun squeezing the electronics into that small space.

    I have been debating battery technology for caves.
    Lithium ion seems ideal, except that the contents are inflammable and in amazingly rare circumstances they have been know to burst into flames - from over-charging - not a problem for you - over heating or physical blows, crushing or piercing.

    So A nice strong box with not too much thermal insulation if you are running them hard.

    Also, a question - what cable are you thinking of using and how would you attach the cable at both ends as these seem to snag on rocks ad get pulled hard.

    As for colour rendering - whatever the apparent colour temperature, 'white' leds have very little green and almost no red in their spectrum, so colour rendering is poor compared with a well-driven halogen lamp.
    I suspect, being incandescent, a carbide lamp had plenty of red and also most of the spectrum - at least as far as blue.

    And - my preference and I know some people here disagree strongly - I favour adjustable light output - either by continuous control or in small steps - or at least three level including an I-am-only-eating-my-sandwiches-and-don't-want-to-blind-everyone setting.

    Happy caving

    Steve
    Last edited by Bandgap; 01-18-2008 at 09:45 AM.

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    Flashaholic* uk_caver's Avatar
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    Default Re: Replacement of carbide lamps by LED lamps

    Quote Originally Posted by Bandgap View Post
    As for colour rendering - whatever the apparent colour temperature, 'white' leds have very little green and almost no red in their spectrum, so colour rendering is poor compared with a well-driven halogen lamp.
    I suspect, being incandescent, a carbide lamp had plenty of red and also most of the spectrum - at least as far as blue.

    And - my preference and I know some people here disagree strongly - I favour adjustable light output - either by continuous control or in small steps - or at least three level including an I-am-only-eating-my-sandwiches-and-don't-want-to-blind-everyone setting.
    Steve
    I can't say I've noticed a colour rendition problem with LEDs when caving, whether illuminating rock or other cavers. Even side-by-side with halogen or carbide, the only obvious difference seems to be in terms of colour temperature, not rendition. I guess there just aren't enough things underground where green is important.
    The place where there does seem to be a difference is on the surface, illuminating grass, etc.

    I like having multiple powers, but after playing around, for practical purposes I reckon power steps of less than a factor of 2 or 3 are probably too close to be useful.

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    Default Re: Replacement of carbide lamps by LED lamps

    Quote Originally Posted by uk_caver View Post
    I can't say I've noticed a colour rendition problem with LEDs when caving, whether illuminating rock or other cavers.....

    I like having multiple powers, but after playing around, for practical purposes I reckon power steps of less than a factor of 2 or 3 are probably too close to be useful.
    Just thought I would point out the colour thing in case there are purists wanting to enjoy strata to the full. I suppose limestone is pretty dull wherever you find it.

    As for the steps, I think steps of 2x or 3x brightness are pretty good- as the eye takes the log (or whatever) of this and makes it apparent steps of 1.4 to 1.7 (ish).
    But they do need to go down far enough IMHO.

    Apart from the cable, my biggest quastion was how to make a switch or control robust enough while keeping it small.

    Steve
    Last edited by Bandgap; 01-18-2008 at 10:31 AM. Reason: addition re. switch

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    Default Re: Replacement of carbide lamps by LED lamps

    Quote Originally Posted by Bandgap View Post
    As for colour rendering - whatever the apparent colour temperature, 'white' leds have very little green and almost no red in their spectrum, so colour rendering is poor compared with a well-driven halogen lamp.
    Perhaps you're thinking of blue leds?
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    Default Re: Replacement of carbide lamps by LED lamps

    Quote Originally Posted by Bandgap View Post
    Just thought I would point out the colour thing in case there are purists wanting to enjoy strata to the full. I suppose limestone is pretty dull wherever you find it.
    I'm not sure about dull, but most of the stuff I've seen underground tends to be somewhere between white, black and brown.
    However, to me, the various kinds of red caving gear still look essentilly the same red under white LED lighting as under daylight, so there's enough red light to allow the brain to construct the impression of a full spectrum.
    I don't need any more red than that, though I can understand some mine explorers looking at subtly different minerals might have a different view.
    Quote Originally Posted by Bandgap View Post
    Apart from the cable, my biggest question was how to make a switch or control robust enough while keeping it small.
    I guess a lot comes down to the casing. If you're making your own housing and trying to avoid possible water ingress points, it's certainly possible to do something with internal reed switches/external magnets. With a cylindrical housing, making an external rotating ring with a magnet in, (as some people do with torches) is probably not too hardto at least get working, though making one that looks good may be rather harder (assuming there isn't some objet trouve lying around that does the business).

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    Default Re: Replacement of carbide lamps by LED lamps

    Quote Originally Posted by uk_caver View Post
    I guess it depends what you mean by 'improve'.

    White LEDs can seem cold, but yellower ones aren't necessarily much better. In the days when I made luxeon-powered lights, and the LEDs I got weren't sold by colour bin, about half were 'proper' white, 30% yellowish, with the rest a little blue (apart from a couple with a purple tint).
    Going straight from using carbide, the yellowish ones maybe seemed a bit less cold than the white ones, but didn't seem quite as good for actually lighting things up, or for colour accuracy.
    I think the old luxeons that were essentially cold white LEDs that ended up being "yellowish" by chance were not the same as current-generation warm white Cree LEDs, which appear closer to blackbody and less "greenish" than bin outliers that just happen to be warmer.

    Equally, though there can be initial comments when switching to a 'colder' light, that does seem largely to be a matter of adjustment.
    I believe different color temps suit different applications. For example, or trying to do intensive shop/design work, I like 5000k. For "ambient" light, I like 3000k. In most other cases, I prefer a compromise of ~3500k. I generally don't like to stray outside the range of 3000k-5000k.

    Also, 'improving' a wide beam is still a matter of taste. Though I'm happy with what I do regarding narrowing a wide beam somewhat, there are certainly people around here who really want a complete 180 degree spread.
    If you want a 180% spread, do your buddies a favor and use a diffuser over the LEDs -- this will help with glare immensely. You can buy lenses from Flashlightlens.com with diffusion film and AR-coatings already installed. I'd recommend a shallow reflector, with a diffuser. This will produce a flood light that still has slightly more intensity in the center of the field of vision (similar to what you'd probably get with a "clean" carbide lamp).

    As for colour rendering - whatever the apparent colour temperature, 'white' leds have very little green and almost no red in their spectrum, so colour rendering is poor compared with a well-driven halogen lamp.
    Most current-generation white LEDs emit the majority of their power in what would be considered the "green" portion of the spectrum -- that is where the high lumens ratings come from (green is where the eyes are most sensitive).The reason older LEDs were much more bluish was that phosphor depositing process was less efficient and would impede light extraction too much, so thinner layers were most efficient. That's improving though -- the fact we have Warm Cree LEDs at Q2 efficiency is evidence of that.

    The problem with color rendition is essentially the same as old single-phosphor fluorescents used to have -- the "red" output is actually more like orange, which is enough to counterbalance the blue and make the overall packaging look white, but provides little contrast when distinguishing shades of red/brown. A potential solution to that is to actually use multiple phosphors with the LEDs, just like modern multi-phosphor fluorescents.

    Maybe for a wide beam, a red or amber LED could be added to the mix to give a more carbide-like light, but I'm not sure many people I know would go for that if it meant extra power consumption/loss of efficiency. It'd also be trickier to match in a focussed beam.
    There isn't much advantage to adding amber -- the only real deficiency is deep red wavelengths. Adding a true red (rather than amber or red-orange) to an array of white LEDs, particuarly ones with a "greenish" off-white tint does produce some very good results. Efficiency loss is neglibile, a surprisingly small amount of red is needed to "fill in the gaps" in the spectrum.

    The problem though is with color mixing/packaging. An actual Emitter package that included a red die INSIDE the package would be pretty interesting, but probably not worth the trouble compared to a second phosphor.
    Last edited by 2xTrinity; 01-18-2008 at 04:34 PM.

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