# Anyone got a triple/quad RED LED?



## deesta (Sep 7, 2008)

Hey guys
I'm doing a rear light and was wondering if anyone had a triple or quad LED board going spare?
Ideally 20-30mm Diameter...anyone got something I can swap for beer tokens?
Steve


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## mattthemuppet (Jul 16, 2004)

don't forget that red LEDs have much lower Vf than white ones, something along the lines of 2V or so.

Just use a piece of red plastic, much easier


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## georges80 (Jan 5, 2010)

mattthemuppet said:


> don't forget that red LEDs have much lower Vf than white ones, something along the lines of 2V or so.
> 
> Just use a piece of red plastic, much easier


Actually the lower Vf would help since Steve wants to use a maxflex from a single li-ion cell.

Also, and this is the REAL point, a white LED has very little energy in the Red spectrum. You really are wasting a lot of lumens, hence runtime (since you'll need the LEDs to be driven at higher current) if you put a red filter/plastic in front of a white LED.... Just look at the spectral power distribution curves of a white LED...

cheers,
george.


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## mattthemuppet (Jul 16, 2004)

I agree about the lower Vf being a plus, just thought it was worth mentioning.

On the subject of efficiency, aren't most red LEDs (XP-E I think is the most recent) far less efficient than current LEDs anyway? Something like [email protected] for Red XP-E (orange-red is ~85) vs. [email protected] for an XP-G2, both for top bins. So, even if 50% of the light from an XP-G2 is wasted going through a red lens, it'll still be more than 50% brighter than a bare red XP-E.


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## georges80 (Jan 5, 2010)

The red from a red LED will be a lot more 'red' than through a filter.

You will lose a LOT more than 50% of the white lumens going through a red filter. Check the spectral power distribution curves of a white LED.... Remember those lumens/watt are across the whole spectrum of the white LED, filter it to Red and you have only a tiny slice of the total lumens/watt...

Here, look at page 6

http://www.cree.com/~/media/Files/C...d Modules/XLamp/Data and Binning/XLampXPE.pdf

Notice how little energy is available at ~630nm on a high efficiency cold white LED. Go to warm white to get more Red and of course you lose lumens/watt and still only get a sliver of the total output.

cheers,
george.


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## mattthemuppet (Jul 16, 2004)

Doh, just realised I was looking at the 700mA values for XP-G2 (smacks forehead)

Taking a warm white XP-G2, 80% of 122 is 97lm, compared with 74lm of a red XP-E. Total consumed power would be 960mW (2.75Vx350mA) vs. 735mW (2.1Vx350mA). Lumens per watt in the red spectrum would then be ~100 for the XP-G2 vs. ~100 for the red XP-E.

Sounds about the same to me, unless I have my maths wrong?


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## deesta (Sep 7, 2008)

My red perspex should be here tomorrow so I'll be able to do a test using a triple XM-L light to see how much red I get from the white LED. I'll try and do some comparison shots..


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## mattthemuppet (Jul 16, 2004)

deesta said:


> My red perspex should be here tomorrow so I'll be able to do a test using a triple XM-L light to see how much red I get from the white LED. I'll try and do some comparison shots..


I wouldn't bother, it'll be too dim to see  (just kidding honest!)


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## troutie-mtb (Sep 20, 2007)

Steve 

I have two red xpes sat on a test heatsink I dont need 
you can have em for the postage and a beer


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## georges80 (Jan 5, 2010)

mattthemuppet said:


> Doh, just realised I was looking at the 700mA values for XP-G2 (smacks forehead)
> 
> Taking a warm white XP-G2, 80% of 122 is 97lm, compared with 74lm of a red XP-E. Total consumed power would be 960mW (2.75Vx350mA) vs. 735mW (2.1Vx350mA). Lumens per watt in the red spectrum would then be ~100 for the XP-G2 vs. ~100 for the red XP-E.
> 
> Sounds about the same to me, unless I have my maths wrong?


Your math is very wrong 

You can NOT compare lumens per watt of a white LED to lumens per watt of a red LED. Lumens are measured across the ENTIRE spectrum of the LED (or light source). In your example above, you certainly do NOT have 97 lumens of RED light in your white warm XP-G2!!! You have 97 lumens across the entire spectrum... The red filter/lens/perspex BLOCKS all light except for Red - so out of that 97 lumens you'll only get a handful of lumens coming through....

USE A RED LED IF YOU WANT RED LIGHT AND GOOD EFFICIENCY... hope I'm not being too subtle 

There is a reason that LED manufactures continue to make monochromatic LEDs versus just sticking a colour lens/filter over a white LED.......

cheers,
george.


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## deesta (Sep 7, 2008)

troutie-mtb said:


> Steve
> 
> I have two red xpes sat on a test heatsink I dont need
> you can have em for the postage and a beer


sounds good to me Chris. I presume they are 20mm stars? Let me know how much and I'll send some beer tokens


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## Toaster79 (Apr 5, 2010)

Matt, this is what the spectrum of an XM-L U2 looks like (and most other CW LEDs)


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## troutie-mtb (Sep 20, 2007)

deesta said:


> sounds good to me Chris. I presume they are 20mm stars? Let me know how much and I'll send some beer tokens


Nope they are on 10 mm squares for a rear you dont need more than 1 and an elliptical optic 
they are very very bright .


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## deesta (Sep 7, 2008)

troutie-mtb said:


> Nope they are on 10 mm squares for a rear you dont need more than 1 and an elliptical optic
> they are very very bright .


Ooh, even better...nice and small :thumbsup: Don't suppose you have any of the aforementioned elliptical beasts?


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## znomit (Dec 27, 2007)

deesta said:


> Ooh, even better...nice and small :thumbsup: Don't suppose you have any of the aforementioned elliptical beasts?


I would recommend holding off on the design until you see one of these lit up. A decent red led at 1W pumps out a lot of light. You don't need to be stingy and use an elliptical, spread the light all over


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## deesta (Sep 7, 2008)

Would 2 x XPE work with the maxFlex? vF of the XPE's is 2.1v, maxFlex will go to 2.5v and battery @ 3.75v?


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## mattthemuppet (Jul 16, 2004)

georges80 said:


> Your math is very wrong
> 
> You can NOT compare lumens per watt of a white LED to lumens per watt of a red LED. Lumens are measured across the ENTIRE spectrum of the LED (or light source). In your example above, you certainly do NOT have 97 lumens of RED light in your white warm XP-G2!!! You have 97 lumens across the entire spectrum... The red filter/lens/perspex BLOCKS all light except for Red - so out of that 97 lumens you'll only get a handful of lumens coming through....
> 
> ...


Oh really? No need to shout 

Check out the relative spectral power distribution on page 3 of
http://www.cree.com/~/media/Files/C... Modules/XLamp/Data and Binning/XLampXPG2.pdf
for the warm white tint.

Relative emission peaks at ~600nm with emission at 630nm being ~80% of that peak. Now taking the total red emission as being 80% of total lumens emitted at 350mA is most likely over simplifying it (as I'm guessing total lumens is the area under the curve), but either way it's clearly not the DIRE SHOUTING WORDS OF DOOM that you keep coming out with. Seriously, I'm not saying red LEDs are crap, I'm just saying that the sweeping dismissive statements you've been making are missing the point.

Sure, in an ideal world, everyone would be hugging each other and using red XP-Es for their tail lights, but if you don't have anyone to hug or a red XP-E to use, you're not consigning yourself to being rear-ended by a semi by using a white LED and red filter.

I have a set up just like that, it's very effective (certainly more than a "handful of lumens"), cars clearly see me and give me a wide berth, the battery lasts for ages, I'm happy. There's no need to take things so personally George.


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## georges80 (Jan 5, 2010)

mattthemuppet said:


> Oh really? No need to shout
> 
> Check out the relative spectral power distribution on page 3 of
> http://www.cree.com/~/media/Files/C... Modules/XLamp/Data and Binning/XLampXPG2.pdf
> ...


Matt, not taking it personally, but YOU are missing the point...

The 80% number you're quoting above for total lumens is NOT how you work it out. Lumens is the integral of ALL the light coming out across the ENTIRE spectrum of the graph. By putting your pseudo-white light of the LED through a filter you are only getting that "sliver" of light energy in THAT BAND that is going through the filter. Furthermore, you have LESS energy in the RED band. So, you have a LOT less lumens coming through the filter as red light. It may still be a lot as far as you are concerned but it is only a SMALL fraction of the total lumens and way LESS that true RED LED.

I'm not shouting doom, I'm just trying to make you and others realise that the output lumens is NOT just the relative level on the curve, it's the relative level on the curve x the integral of power under the red section of the curve... i.e. if you have 100 lumens of white light and the red component is say 70%, you do NOT have 100 x 70% = 70 lumens of red... Say the RED part of the white LED output is 10% of the total white spectrum. What you then have is closer to 100 x 70% x 10% = 7 lumens... Get it??

I'm not saying that a white LED through a LED filter won't give you red light, what I'm saying is that you are giving up a huge amount of efficiency and runtime since you'll be lucky to get 10% of the total lumens coming out as red.

Just trying to educate and clarify your misconception that the efficiency (lumens/watt) of white LED light going through a red filter (to get red light) will be close to a RED LED, which is your original claim...

cheers,
george.


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## mattthemuppet (Jul 16, 2004)

well, if you want someone to increase their understanding of a subject, shouting at them isn't the best way to do it.

My original point was that the decrease in efficiency of a white LED shining through a piece of red plastic is partially off-set by the increase in efficiency of newer tech LEDs. I'm sure you'd be more than happy to keep shouting at me to correct my misconceptions (which have, admittedly, been somewhat reduced by this process), but my real world experience, and that of others, suggests that reality lies somewhat in between the two of us. Perhaps because we aren't using precise band gap filters from a laboratory microscope as red lenses (therefore allowing more of the spectra under that power curve through than you state), perhaps because, horror of horrors, I'm not actually blowing smoke out of my ar$e. Either way, I'm happy to concede to that grey area and I've learnt a lot from the process. However, in the context of the real world, I am not missing the point.


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## georges80 (Jan 5, 2010)

Matt, I use uppercase words in my posts above to highlight the key terms. I'm not shouting...

The real world is about runtime and output. The white LED, especially the common cold white (which are the high efficiency) have little energy in the red spectrum. The result is you'll get maybe 10% of the white lumens as red light coming out, even with some red perspex. So, even if you have 150 lumens per watt, you'll be getting maybe 15 lumens per watt of Red. Obviously if your red filter lets through yellow then fine, you'll get more lumens, but now you have an orange tail light...

Maybe that's ok for your tail light, but I'd rather extend my runtime by 4 to 5X and use a 70 lumen/watt red LED and underdrive it and still get more red light.

Your original statement was:

"On the subject of efficiency, aren't most red LEDs (XP-E I think is the most recent) far less efficient than current LEDs anyway? Something like [email protected] for Red XP-E (orange-red is ~85) vs. [email protected] for an XP-G2, both for top bins. So, even if 50% of the light from an XP-G2 is wasted going through a red lens, it'll still be more than 50% brighter than a bare red XP-E"

And my statement is the loss is a LOT more than 50% going through a Red filter, more likely 90% or more, because you a) are only extracting the red part of the spectrum which is already at a lot lower energy than the green/blue and b) introducing transmissive losses due to the plastic filter. 

Just realise that you are getting a LOT less lumens/watt of red light and even a 2x lumen/watt efficiency of a white versus red is still several several factors less red light. So you would need to run several factors more current and that much less runtime.

Anyhow, I think this horse is sufficiently beaten to death and those that want to use white leds and red filters are free to do so 

cheers,
george.


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## vroom9 (Feb 24, 2009)

Another vote for using an actual red led.



mattthemuppet said:


> I agree about the lower Vf being a plus, just thought it was worth mentioning.
> 
> On the subject of efficiency, aren't most red LEDs (XP-E I think is the most recent) far less efficient than current LEDs anyway? Something like [email protected] for Red XP-E (orange-red is ~85) vs. [email protected] for an XP-G2, both for top bins. So, even if 50% of the light from an XP-G2 is wasted going through a red lens, it'll still be more than 50% brighter than a bare red XP-E.


There is something missing from this analysis.

One thing that I didn't see is a description of what lumens actually are. They are based on the sensitivity of our eyes. This is huge. Our eyes have wild changes in response to various colors. The peak is in the green at about 555nm. At this wavelength one watt of light is 683 lumens. In the red at 680 nm that same watt is only good for about 14 lumens. This is why red leds seem inefficient. It's not the LED that is poor in efficiency, it's your eyes.

Really go with red LEDs. The efficiencies will be at least ten times more than using white with a filter. There is no way that you will get more than 10 lumnes per watt using a filter on a white LED, and I would guess 5.

XP-E's are available in red. Those will work well.



georges80 said:


> Anyhow, I think this horse is sufficiently beaten to death and those that want to use white leds and red filters are free to do so


Sorry I had to get one more blow on that horse.


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## deesta (Sep 7, 2008)

I feel fully educated on the pro's and con's of using red or white LED's.

As I may be having 2 red XPE's off Troutie, I'll give them a go. Also, because they are nice and small it will help keep the housing smaller too..
Would these 2 XPE's be driven ok by the maxFlex 5 I have? I'm planning on using a single 3.75v 18650.
Finally, as I've already ordered it, would the red perspex have a major impact on the light output (colour wise)?? I'm thinking of running them without optics..


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## mattthemuppet (Jul 16, 2004)

georges80 said:


> .. and those that want to use white leds and red filters are free to do so


phew, thanks! I was just about to throw my tail light in the bin!

Thing is, I understand the theory of why red LEDs are better; clearly, emitting light in your desired wavelength is going to be more efficient than emitting a broad spectrum of light and cutting out a big chunk of it. I get that, I'm not stupid.

However, the repeated assertions that doing so will only let a "sliver of light through" and "no more than 10% of the lumens produced" in no way tally with my own personal, empirical experience. There's no way my tail light produces only 10-30 lumens, no way at all. It's many times brighter than the standard PBSF lights and equivalent to a Dinotte 100R. Perhaps because it is orangy-red, I don't care. If our eyes are less responsive to red light, then building a light using exclusively a wavelength we're less responsive to seems dogmatic at best. It's not like drivers see a bright orange-red tail light and are somehow less likely to pay attention to it than a red tail light of equal brightness.

As for real world considerations, if you want to use a single red LED off a single li-ion, then you'll need to use a buck driver otherwise the excess voltage burnt off by using a linear regulator (eg. an Lflex or any of the AMC7135 drivers) otherwise you'll negate some of the efficiency benefits of using a red LED. That raises costs, complexity and adds packaging considerations. Two red LEDs, ditto, but more so. A red triple, ditto. Sure, I'm bet they'd all make awesome lights, most likely better than mine, but they'd also cost a huge amount more too. Besides, all this talk of runtime and the like - these are going to be commuter lights and even my nut job of a brother doesn't commute for more than 30-45min each way - my light would last him a whole week without recharging and when it runs out he'd just have to plug it into a USB port. Plus that's not even with a decent battery.

As for beating a dead horse, someone telling me, an empirical scientist, that fact sheet values trump personal experience, nah, that's not going to happen. In fact, if we're straight on "area under the spectral power curve = total lumens" then the area under the curve of a warm white XP-G2 for the red part of the spectra (620-750nm) is going to be ~25% by eyeball. Extend that out to orange (590nm-620nm) and you're looking at ~45%. Even with a CW tint, that's 15% to ~30%. Neither are a "sliver of light".

BTW, have you even tried a modern white LED behind a piece of red plastic or is this all just theory? Do you even commute by bike at night?


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## mattthemuppet (Jul 16, 2004)

deesta said:


> I feel fully educated on the pro's and con's of using red or white LED's.


it's been a pleasure :thumbsup:


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## mattthemuppet (Jul 16, 2004)

georges80 said:


> Matt, I use uppercase words in my posts above to highlight the key terms. I'm not shouting...


oh, forgot to say, most people, including myself, are suitably proficient at reading comprehension not to need little bits underlying for us. It just comes across as childish or patronising.


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## mattthemuppet (Jul 16, 2004)

vroom9 said:


> There is something missing from this analysis


the correct figures?! For some reason I looked at the 700mA column for the lumens of the XP-G2, instead of the 350mA column  Corrected in later analyses..


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## georges80 (Jan 5, 2010)

The horse is definitely dead. You're convinced your filtered white light is more than 10 lumens and if that's what you believe, good onya. 

I've put LEDs behind filters, that's why I KNOW to use a RED or YELLOW LED when that's the colour I'm after versus a white behind a filter.

Seriously, just look at the spectral charts (those are fact and real world). Now put it over some grid paper an count the grids that are under the RED. Count the grids under the entire spectrum. Divide the RED grid count with the total grid count. That's you RED output - less losses through the filter. That's real world, the math/curves/data IS the factual data.

Your eye is has a peak sensitivity in the yellow/green region, so you may think you're got a lot more light but that is "perception" not fact. The fact is if you had a RED LED you could get as much "perceived" light with a fraction of the current (like 10% or less) than is needed with a white LED and a red filter.

The human eye perceives light on a log scale, so 100 lumens is not 10 times brighter than 10 lumens.... So 10 lumens (especially at night) can still appear like a lot of light. Just to reinforce one more time (since the horse now is starting to smell), putting a RED filter in front of a white LED is blocking (wasting) all those photons that are not in the RED spectrum, the filter doesn't "convert" the light colour... Go get your grid paper and spectral curve out and do the math - that's the real world...

Steve, if you run 2 xpe in series, the total Vf will be maybe around 4 or so volts at lower current, so it'll direct drive through the maxflex if the battery voltage is higher than the Vf (at the set current). 3 series RED LEDs would be a safe configuration and a LOT of red light! You probably want to run the RED LEDs with a power supply and get a feel for their Vf at 100 - 350mA to see if you'll have direct drive issues.

cheers,
george.


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## troutie-mtb (Sep 20, 2007)

I have a 3 red XPE light running from a Maxflex 5 from a 3.7 v source on my hardtail 
and very bright it is 
here is a very shaky vid I took today in daylight

GOPR0006 - YouTube

Question for George 
how well would a pair of red xpes run from a single Li Ion and an Lflex


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## vroom9 (Feb 24, 2009)

mattthemuppet said:


> the correct figures?! For some reason I looked at the 700mA column for the lumens of the XP-G2, instead of the 350mA column  Corrected in later analyses..


I was just trying to add that a lumen is not a measure of power. It's a measurement of apparent brightness through our imperfect eyes. This makes the red LEDs seem to have poor efficiency.

For example a white LED might be 100 lumens/watt and a red one only 30 lumes/watt. If you look instead at the watts of light output the red may well have higher overall efficiency at turning electrical power into photons of light.


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## mattthemuppet (Jul 16, 2004)

vroom9 said:


> I was just trying to add that a lumen is not a measure of power. It's a measurement of apparent brightness through our imperfect eyes. This makes the red LEDs seem to have poor efficiency.
> 
> For example a white LED might be 100 lumens/watt and a red one only 30 lumes/watt. If you look instead at the watts of light output the red may well have higher overall efficiency at turning electrical power into photons of light.


thanks, it was a useful addition to the discussion. I imagine our lower sensitivity to red light is a consequence of it's relative prevalence in daylight/ light reflected off vegetation and the evolution of the eye. No point being super sensitive to something we don't see much of


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## georges80 (Jan 5, 2010)

troutie-mtb said:


> I have a 3 red XPE light running from a Maxflex 5 from a 3.7 v source on my hardtail
> and very bright it is
> here is a very shaky vid I took today in daylight
> 
> ...


Chris,
all depends on the Vf of the Red's, I assume they're up in the 2.1V range (higher and higher current). So to have the lflex in regulation you of course need input voltage to be higher than LED Vf, otherwise the driver just goes 100% and the LEDs will take whatever current they can at that battery voltage.

i.e. if Red LEDs's Vf is say 2.1V at 350mA, then 2 in series is 4.2V. Say you battery is at around 3.7V, then the driver will go to 100% and supply 3.7V to the LEDs and they'll draw less than 350mA...

4 series nimh cells would be a good choice for an lflex and 2 series Red XPE's assuming you don't get 2.5V Vf ones....

cheers,
george.


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## mattthemuppet (Jul 16, 2004)

georges80 said:


> The horse is definitely dead. You're convinced your filtered white light is more than 10 lumens and if that's what you believe, good onya.
> 
> I've put LEDs behind filters, that's why I KNOW to use a RED or YELLOW LED when that's the colour I'm after versus a white behind a filter.
> 
> ...


wow, is this part of some kind of PR drive for Taskled as a company? If it is, I'd fire your PR rep.

well, I broke out my fingers and took off my shoes so I count above 10, and counted all those tricky squares on that pdf thing. Looks like the relative spectral power distribution for an XP-G2 WW is split about 1:1 above and below 590nm. I don't have any grid paper as I'm not at kindergarten any more and my thumbs are too big to hold up to my computer screen, so I'm sure there's some degree of error in there. Now, if I remember correctly 1+1=2, so 1 over 2 must be one half. I got some help and found out that half of 122 is 61, which is an ever so big number and, I'm told, not that much smaller than 74.

Some wag also told me that perception is 9/10 of the law, but I think he was joking


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## troutie-mtb (Sep 20, 2007)

Thanks George 
Quite happy with the triple red and Mflex only charged the battery once last year 
and used it lots .
got to admit it took me by surprise as I originally put a 7.4 volt battery on it and didnot realise the lower vf of the 3 reds ( as a typical male i did not RTFM of the reds ) 
it was very bright when I switched it on 



georges80 said:


> Chris,
> all depends on the Vf of the Red's, I assume they're up in the 2.1V range (higher and higher current). So to have the lflex in regulation you of course need input voltage to be higher than LED Vf, otherwise the driver just goes 100% and the LEDs will take whatever current they can at that battery voltage.
> 
> i.e. if Red LEDs's Vf is say 2.1V at 350mA, then 2 in series is 4.2V. Say you battery is at around 3.7V, then the driver will go to 100% and supply 3.7V to the LEDs and they'll draw less than 350mA...
> ...


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## deesta (Sep 7, 2008)

If only you had 3 not 2 of the xpe's Chris. I'll take the 2 if you've still git them and try and source another one to go with them...


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## deesta (Sep 7, 2008)

*Red filter works but eats lumens..*

I've just had my red perspex arrive so did a quick test to see how it would work...I did take some photo's but they don't really show the difference..To the naked eye, the difference is huge!

With the 3 x XML on low, without filter, it was blinding.
with the red filter, it was bright but I could still see the LED through the light.

Red LED's it is for me then :thumbsup:

edit: just done a couple of quick photo's in the back garden...no proper settings, just phone camera but you can see the difference in the light output. Although I think it would be OK to run red filter on white led's in terms off performance it's got to be red I reckon.


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## deesta (Sep 7, 2008)

Been busy on the machine today....housing nearly finished. Just need to do the led pocket and then wait for the postman with my battery off Smudge and LEDs from cutter....
It's a bit bigger than some back lights but should be plenty bright enough :thumbsup:


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## deesta (Sep 7, 2008)

*Some pics...*

A few pics (without the LED pocket & lens)


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## mattthemuppet (Jul 16, 2004)

interesting pics and the housing looks very pretty. The battery is going inside, right? Are you going to use any optics or have them bare under the lens?

looking forward to the finished product!

btw, used my rear light on the commute this morning, as it was hissing it down and I had to use the road. Helped a great deal with visibility (even with the tag-a-long in the way) and cars gave me a wide berth. Tail lights are not just for the night


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## Goldigger (Nov 6, 2009)

deesta said:


> A few pics (without the LED pocket & lens)


That's some beautiful machining..:thumbsup:

you got me thinking about rear lights now..part of my night route involves a bit on the road..
I'm thinking of a light that clamps round the seatpost..extra heatsinking..
not sure if i will use a single led with a lflex or maybe one of quazzles tripple boards with red leds..


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## deesta (Sep 7, 2008)

*A bit more done..*

Thanks guys. I'm pretty pleased with it, although time will tell if it was wise to go with delrin for the main housing. Hopefully not much heat due to being run on low power and strobe..
The TF battery is only for show, will have a nice new one from Smudge soon


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## wquiles (Aug 22, 2010)

Very nice machining


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## mattthemuppet (Jul 16, 2004)

ah, I didn't realise the housing was delrin, thought it was anodised aluminium. Why the fins though, if it's not going to be playing any role in heat dispersal?


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## deesta (Sep 7, 2008)

mattthemuppet said:


> ah, I didn't realise the housing was delrin, thought it was anodised aluminium. Why the fins though, if it's not going to be playing any role in heat dispersal?


Purely cosmetic (and shave a bit of weight off)...I'm also hoping that, with the red filter visible from the side, some light may be visible from the sides too...maybe??

just waiting for a battery and the red led's to arrive....


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## Ofroad'bent (Jul 10, 2010)

Got my red LED and a driver from KD. I'll just set it up in a P50 drop-in to stick in a rear vent of my helmet.

Now I have to decide between High-Off-10hz flash or High-Off-Med-Off-2Hz flash. I would really prefer just Flash-Off- Flash.

Either one beats the heck out of the High-off-mid-off-low-off-flash-off-SOS I currently have (and hate- too many clicks to get to flash) This will be an upgrade.

Not as pretty as Deesta's of course.


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## ThinkBike (Jun 16, 2010)

Found a double triple XP-E red tail light with a max of 10 watts. Designshine. Uses a Maxflex6. Looks like the guy started out as a DIYer and turned it into a business. I like the fact that the light is also visible from the sides. It certainly looks bright!


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## Vancbiker (May 25, 2005)

ThinkBike said:


> Found a double triple XP-E red tail light with a max of 10 watts. Designshine. Uses a Maxflex6. Looks like the guy started out as a DIYer and turned it into a business. I like the fact that the light is also visible from the sides. It certainly looks bright!


The builder of Designshine posts on MTBR forums as pethelman. He has numerous posts over on the lights and night riding forum


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## Ofroad'bent (Jul 10, 2010)

I just modified a red P60 drop-in with this board.
https://www.kaidomain.com/product/details.S020075


















Set it up for High/10hz strobe. Man, that's eye-catching, even in daylight.
Far better than having to cycle through the 5 modes I had earlier.

I think I'll cut off one of the 4 power chips, so it runs a bit lower on high.

I'm thinking of seeing if I can just wrap the drop-in with heat-shrink and use that in the back vent of my helmet.


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## pethelman (Feb 26, 2011)

Vancbiker said:


> The builder of Designshine posts on MTBR forums as pethelman. He has numerous posts over on the lights and night riding forum


Yes, and I finally found a talented CNC "artist" who can really take the design to the next level. Every interface is now o-ring sealed: Lens-cover to lenses, lens-cover to main body, and lid to body. The lens cover can be removed for changing out the type and/or orientation of the elliptical lens. Check out the new housings... the Philips screws were just temporary. To be replaced with socket head. The head and tail share the same body, but the lid becomes a "visor" for the headlight to protect the rider from the light projected through the side of the lens cover. Anodized housing on left was from build #2 with lid sitting on top, aluminum build #3 prototype on right with integrated lid.

On topic, however, two triple RED XPE definitely like to have this much cooling surface area (roughly 30 sq inches with this housing) when driven to the max , even when flashing. You can get by with less, but I prefer a conservative design that gives a good amount of "buffer zone" so that stopping at intersections for a few minutes on a hot summer day won't get into the thermal protection zone.


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## Wombat (Jan 25, 2004)

That's gorgeous. How long before you'll be selling them?

Tim


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## pethelman (Feb 26, 2011)

Wombat said:


> That's gorgeous. How long before you'll be selling them?
> 
> Tim


I've been taking the slow/steady approach and have been proving out the design, working out better methods of sealing, anodizing, assembly, flash modes, higher power LEDs, etc. over the last year and a half (there are a few user reviews here on MTBR). There're probably 100+ or so running around on the roads at the moment. I started the whole project, like many of the guys here, because I wanted to build my "ideal" taillight, not really thinking about going into business. Of course, then that turned into adding a headlight to the mix and then the "problem" became that they worked really REALLY well. But it's also more work (and TIME) than I ever imagined, and now I don't have the financing or the manpower to take it to a larger scale. I'm currently building around 100 new taillights and 39 headlights, and they're all already pre-sold. So, after this batch, I'm going to take a breather and figure out what needs to happen next. I'd really hate to see the taillight disappear, because I truly believe it could be a real live saver amongst the ever increasingly distracted driver population. Oh well, thanks for letting me wax on...


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## VegasF6 (Jul 15, 2010)

deesta said:


> Purely cosmetic (and shave a bit of weight off)...I'm also hoping that, with the red filter visible from the side, some light may be visible from the sides too...maybe??
> 
> just waiting for a battery and the red led's to arrive....


Pretty slick housing there, really good work.

Do I understand you that the window is going to be red tinted plexi (or perspex  ) ?
Not interested in the flame war going on above, but I do want to point out that the disadvantages associated with filtering white a white led through a red window also exist using a red led with a red window. Maybe to a lesser extent, but it is still a factor. The color spectrum of your led will not perfectly match the filtering properties of window and some output will be lost. Red plexi makes a very imperfect light filter so it will allow a percentage of light to pass even if it isn't within the same spectrum. Same reason why led behind smoke tinted lens will still allow light through. If only the black colored light was escaping you wouldn't be able to see much 
So, in my opinion at least, you will be better off with a clear window. It may only block ~ 10% of visible and invisible light. 
If I misunderstood, forgive me.

Are you concerned with UV resistance at all? I assume you won't be leaving it out in the sun for extended periods of time?


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## Praxis (Apr 30, 2007)

So, not to throw gasoline on this or anything...

If I understand both sides correctly, George is saying "a red lens is WAY worse than a red LED", and Matt is saying "Maybe so, but it's close enough." As is usual, I suspect both sides have a point. My guess is that the red led puts out more light in the narrow red part of the spectrum, and that the lens that Matt is talking about is probably putting out a much wider spectrum which makes it appear otherwise brighter. But I could be wrong; it's just a guess.

Can someone measure the difference? Has anyone measured the difference? It would seem like we'd actually need to measure the brightness at different wavelengths to make it fair.


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## mattthemuppet (Jul 16, 2004)

George is right, the red XP-E behind a clear lens is going to be brighter than a white LED behind a red lens, I was just trying to make the point that the increased efficiency of newer LEDs may close some of that gap, depending on LED tint and the red lens used.

Red XP-Es are somewhat of a pain to use as their Vf doesn't easily match the voltage of a single Li-ion cell (perfect for 2 NiMh AA though), so you need to use a more expensive driver or more LEDs, which can complicate the build, especially if you're building small. So, in an ideal world red XP-E(s) are the way to go (even more so if they release a red XP-E2), but if cost or simplicity is a consideration and you can get the brightness/ runtime you need, a white LED (esp. WW tint) behind a red/amber lens will still make a great light. Note though that a pure red filter, especially a strict band gap filter (say 590-620nm), will cut out far more light than the red(ish) bicycle reflector I scavenged form the bike shop (which also has a cool faceted inner face which sends light towards the front of the bike).

I don't think there's anything too contentious about that


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## pethelman (Feb 26, 2011)

*To filter or not to filter...*

Way back when, I used one of these: 
Maglite red filter lens, which are still available on ebay.

Dremel tooled down to size and put over a 200 lumen flashlight. It did work well, but as documented in this thread, not nearly as efficient as a comparable intensity RED LED.


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## Ofroad'bent (Jul 10, 2010)

Ofroad'bent said:


> I just modified a red P60 drop-in with this board.
> https://www.kaidomain.com/product/details.S020075
> 
> 
> ...


Here's how the little vent light turned out. It's very bright and eye catching, and has only 2 modes, high and 10hz crazy flash.

Here are the various parts:









From right to left- Lens, Little optic to act as diffuser, P60 reflector, Red Cree LED in pill with modified KD driver, plastic cable gland, wire and connector and switch, with heat shrink to cover it all.

I actually used one of EL34's Marwi switches. The parts were all probably under $20, except for the $15 shipping from EL34, which I luckily combined with other stuff.


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## mattthemuppet (Jul 16, 2004)

man, that's going to be insanely bright - 1.5A strobe! I don't think you'll have any trouble getting noticed at all  What battery are you going to run it off - your main one via a Y or a separate one?

good to see the cable gland found a use!


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## deesta (Sep 7, 2008)

*All done...*

Finally got the rest of the bits to put this light together (thanks Mark @cutter and Smudge for the battery) :thumbsup:

Really please with the output and light colour (even through the red lense). Just need darkness to test it properly. External charging works a treat too. Modified a normal 18650 charger to have a 2.5mm male socket and re-wired so that I can plug the light into the charger.
Should be fully waterproof as the front is sealed with an o-ring, the switch is IP67, the charging point has an o-ring sealed cap and the 2 halves are silicon sealed.
Weighs in @ 175g complete too so well happy with that. (I know there are lighter back lights out there but I made this one )


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## Ofroad'bent (Jul 10, 2010)

mattthemuppet said:


> man, that's going to be insanely bright - 1.5A strobe! I don't think you'll have any trouble getting noticed at all  What battery are you going to run it off - your main one via a Y or a separate one?
> 
> good to see the cable gland found a use!


Running it on 1A with one of the chips removed. It'll run from a single waterproofed 18650 battery mounted on the helmet.

Should be good daylight visibility.


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## mattthemuppet (Jul 16, 2004)

deesta said:


> Finally got the rest of the bits to put this light together (thanks Mark @cutter and Smudge for the battery) :thumbsup:
> 
> Really please with the output and light colour (even through the red lense). Just need darkness to test it properly. External charging works a treat too. Modified a normal 18650 charger to have a 2.5mm male socket and re-wired so that I can plug the light into the charger.
> Should be fully waterproof as the front is sealed with an o-ring, the switch is IP67, the charging point has an o-ring sealed cap and the 2 halves are silicon sealed.
> Weighs in @ 175g complete too so well happy with that. (I know there are lighter back lights out there but I made this one )


nice job! No pics = didn't happen though 



Ofroad'bent said:


> Running it on 1A with one of the chips removed. It'll run from a single waterproofed 18650 battery mounted on the helmet.
> 
> Should be good daylight visibility.


ah, that makes sense. Although, if I'm being a pedant (who, me?) that'll be 1140mA


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## deesta (Sep 7, 2008)

mattthemuppet said:


> nice job! No pics = didn't happen though


A few things I learnt along the way:

As it's a all-in-one rear light I used Dean's connectors to make assemble easier. Setting the maxflex (UB2Q) was, initially, a problem as I had to de-solder the battery to make alterations. With the Dean's I could just unplug it.
I can make this quite a bit smaller as the battery is a bit smaller than I thought and I'd allowed extra on the casing. Could loose about 6mm on the overall width. 
Would probably mount the switch and charging point differently on v2.

Here you go then....


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## Goldigger (Nov 6, 2009)

mattthemuppet said:


> nice job! *No pics = didn't happen though *
> 
> ah, that makes sense. Although, if I'm being a pedant (who, me?) that'll be 1140mA


That made me laugh...reminds me of one of the other forums I visit, where the subject of the thread is always a female.. someone always posts "post a pics or she's not real and this thread is BS"..lol


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## mattthemuppet (Jul 16, 2004)

interesting - I completely didn't expect it to look like that for some reason. I'm guessing you still get some visibility out of the sides due to the perspex?


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## deesta (Sep 7, 2008)

mattthemuppet said:


> interesting - I completely didn't expect it to look like that for some reason. I'm guessing you still get some visibility out of the sides due to the perspex?


Yeah, do get some side visibility which I'm pleased about. I think there may be a v2 in the pipeline as I've learnt a few things so should be able to improve size/weight etc...


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