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  1. #1
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    Rear Light Project - advice required please

    Hi all,
    Im looking to modify an existing rear housing by removing the standard leds within and replacing with something a little brighter.

    I found an article on Indestructibles which used a Luxeon 3-watt red/orange high power led powered by 2xAAA..
    http://www.instructables.com/id/Ulti...o---100-Lumen/

    Ive found that Farrells stock the leds with & without Star board.
    spec of lamp is: LED, LUXEON III, RED, ORANGE
    Series:LUXEON III; LED Colour:Red Orange; Luminous Flux @ Test:190lm; Wavelength Typ:620.5nm; Forward Current @ Test:1.4A; Forward Current If Max:1.54A; Forward Voltage @ Test:2.95V;

    Questions:
    1. Do I need to use the Starboard or can I solder straight to the LED only version to save space? The board doesnt appear to be a heatsink as as Im not going to be running the lamp near max I shouldnt need regulation, and Im thinking heat shouldnt be a problem.

    2. Is there a way I could use more than 1 of these LEDS in the same housing and if so would that mean wiring differently or additional electronics?

    3. Have any of you done something similar or can advise of something better.
    The light is to be used on the road bike, but also when riding to trails. So I need something small & interchangeable between bikes.

    Thanks in advance for any assistance

  2. #2
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    Quote Originally Posted by griffter18
    1. Do I need to use the Starboard or can I solder straight to the LED only version to save space? The board doesnt appear to be a heatsink as as Im not going to be running the lamp near max I shouldnt need regulation, and Im thinking heat shouldnt be a problem.
    Heat will be a problem, especially if you won't use a driver/resistor to limit LED currency (cause LED could drain all the ampers it could get from the power source).
    So, you'll need a driver and/or some radiator.

  3. #3
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    This light could be a great starting point, or this drop-in.
    in a standard host.
    You could get fancy and attach magicshine connectors to the head and a heat-shrink- wrapped battery.

  4. #4
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    I don't think you are going to gain enough intensity to make it worth the cost and effort, since the existing circuitry is not going to feed enough current to the emitters to make it substantially brighter. If you add juice, then you are going to have a heat issue.

    If you enjoy being a "maker," you could make a nice rechargeable taillight out of the following that would be superior to any off-the-shelf lights priced under $100:

    18650 battery Li-Ion (or 2 NiMh) $6 to $20
    Red Cree emitter on a star $9
    Copper pipe cap with a diameter of at least 20mm (plumbing section at hardware store) $1
    Carclo 10mm optic (narrow) $3
    LFlex driver $25
    heat shrink tubing <$1
    6mm tactile switch <$1
    20 or 22 AWG cable and connectors (<$2.00 on DX)*
    Arctic thermal paste
    Lexan sheet (<$1.00 at welding supply store)
    Two-part Epoxy

    You can set the LFflex to flash and have a thermal cut of 50 to 60C.

    Think ahead about your mounting options, since you will probably want to have a bolt or somesuch sticking out, or a locknut glued inside the housing for mounting. Or you could solder an area to allow threading a piece of velcro through to affix to the seat post.

    * - you could spend a few bucks more and get magicshine cables from DX that will be more durable.

    If this sounds like to much work, your next best bet is to buy a $30 PBFlash, or a Mars, or (my favorite) a Danger Zone by Portland Design Works. I use the latter and find it to be adequate.


    It would look something like this when finished:

    Last edited by P220C; 03-19-2011 at 11:34 AM.

  5. #5
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    when I get off my butt and finish building a new bar light, I'm going to make a little sled-style rear light (see Ofroad'bent's XML sled light some threads below) with an old XR-E star, a 350mA AM7135 driver from KD, Magicshine cable and single 18650 cell. I've got plenty of old LED rear lights to scavenge for red lenses and I'll switch it on just by plugging it in.

    I figured that 350mA should give me ~70lm (no idea on XR-E bin though) and excellent battery life. If it's not bright enough I'll just solder another AM7135 chip onto the board to get 700mA as I have several spare drivers..

  6. #6
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    You'll get way more light out of the old luxeon III red-orange (it looks way more red than orange). Lumileds stopped making them last year, but you can still get 'em on a star from: http://ledsupply.com/lxhl-lh3c.php

    Led Supply also carries pretty nice wide optics: http://ledsupply.com/l2-op-025.php

    The next brightest LEDs (at a reasonable price) that are still being manufactured are the amber ones from Osram. They look pretty darn red to me. You can usually find them at mouser.com or digikey.com. The Golden Dragon Plus LEDs have a nice price/performance point. The Diamond Dragons are probably the absolutely brightest until you start looking at something like a red SST-90 (woah 750+ lumens).

    I'd look at running your sled-light around 500 mA or more. Should produce enuff light to be visible in daylight.

    For power, I'd look at using a Li-Ion 18650 or at least a couple of AA NiMH batteries.

    Mark
    Nimium est melior!

  7. #7
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    thanks for the tips mhahn. I'll definitely look into red LEDs for a future one, but at the moment old LED + red lens = free, which is pretty cheap All in cost should be ~$10..

  8. #8
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    If I rode the roads at night, I would use a taillight that had the ability to flash. That seems far more capable of getting a drivers attention than a steady red.

  9. #9
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    Quote Originally Posted by Vancbiker
    If I rode the roads at night, I would use a taillight that had the ability to flash. That seems far more capable of getting a drivers attention than a steady red.
    you know what they say about the word assume I have a perfectly capable flashing LED light already thanks, this steady light would be in addition to that. Plus, I wanted a single mode driver that put out <700mA that would give me long battery life and could be switched on simply by plugging in the battery.

    There are more than enough cheap drivers on DX/ KD that have both steady and flashing modes (unless the OP take P220C's worthy suggestion of an lflex) that others on here have far more experience with than I do. I'm sure the OP would appreciate any suggestions..

  10. #10
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    this is my rough cobbled together rear incorporated into my double xml helmet light



    used 2 red xpes no optics needed and a teapot 350ma driver plenty bright and viewable from a very wide angle .
    one good thing is I never forget to take it with me on a night ride

  11. #11
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    Quote Originally Posted by troutie-mtb
    used 2 red xpes no optics needed and a teapot 350ma driver plenty bright and viewable from a very wide angle .
    one good thing is I never forget to take it with me on a night ride
    that was the very light that set me thinking about making my own rear light I'm sure that if inspirationometer was a word, yours would be bouncing around at no. 10!

  12. #12
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    Quote Originally Posted by griffter18
    Hi all,
    Im looking to modify an existing rear housing by removing the standard leds within and replacing with something a little brighter.

    I found an article on Indestructibles which used a Luxeon 3-watt red/orange high power led powered by 2xAAA..
    http://www.instructables.com/id/Ulti...o---100-Lumen/

    Ive found that Farrells stock the leds with & without Star board.
    spec of lamp is: LED, LUXEON III, RED, ORANGE
    Series:LUXEON III; LED Colour:Red Orange; Luminous Flux @ Test:190lm; Wavelength Typ:620.5nm; Forward Current @ Test:1.4A; Forward Current If Max:1.54A; Forward Voltage @ Test:2.95V;

    Questions:
    1. Do I need to use the Starboard or can I solder straight to the LED only version to save space? The board doesnt appear to be a heatsink as as Im not going to be running the lamp near max I shouldnt need regulation, and Im thinking heat shouldnt be a problem.

    2. Is there a way I could use more than 1 of these LEDS in the same housing and if so would that mean wiring differently or additional electronics?

    3. Have any of you done something similar or can advise of something better.
    The light is to be used on the road bike, but also when riding to trails. So I need something small & interchangeable between bikes.

    Thanks in advance for any assistance
    That was one of the first rear bike light setups I ever built.

    Meanwhile, the one and only that has been serving my needs since 2009 looks like this:




    It is a non-blinking unit. It uses two of these nice bright 9-emitter red LED modules, driven by one 1000mA 3023 non-dimmable BuckPuck. The optics and optic housings are from DealExtreme, they are these ones, but I replaced one of the optics with a longer throw one so it has both a long and narrow throw. The housing is just basic 1" square extruded aluminum, cut in places, and joined together with JB Weld. Really low-tech, and packs a PUNCH!!! Oh yeah, powered by one 14.8V 4400mAh 8-cell 16850 Li-Ion pack. It can be seen for SEVERAL MILES in BROAD DAYLIGHT!!!
    QUOTE from MTBR.COM: You have given Brewtality too much Reputation in the last 24 hours, try again later.

  13. #13
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    Hello guys, I just wonder, have you tried to stand up behind these lights and look into them at night? These constructions are really "selfish" - will make the person following you completely blinded (and thus not seeing holes in street...). So please be kind and add some capability to dim the lights significantly if needed... Thanks

  14. #14
    meep meep !!!
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    Or you could just cycle faster, then you would be in front..................

  15. #15
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    Yeah, I'ts easier to say than to do (esp. after 140km with full baggage) . Just following someone with two Smart Superflash tail lights (and these are far form the DIY ones) was pain in the ass after half an hour... And only one in the group can be the first one....

  16. #16
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    Quote Originally Posted by mattthemuppet
    when I get off my butt and finish building a new bar light, I'm going to make a little sled-style rear light (see Ofroad'bent's XML sled light some threads below) with an old XR-E star, a 350mA AM7135 driver from KD, Magicshine cable and single 18650 cell. I've got plenty of old LED rear lights to scavenge for red lenses and I'll switch it on just by plugging it in.

    I figured that 350mA should give me ~70lm (no idea on XR-E bin though) and excellent battery life. If it's not bright enough I'll just solder another AM7135 chip onto the board to get 700mA as I have several spare drivers..

    How big is the driver? Think we can fit it in a 3/4" tubing?

  17. #17
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    Griffter: Some info on brightness is helpful in planning a tail light. There is not a lot of comparisons when I was looking.

    A pair of DIY non-blinking 100 lumen tailights (a bit brighter than a Dinnote 140 and brighter than a car's brake lights but bigger in perceived size, were the reason for the video comparison. Cost: $37 the pair sans battery pack. You can mount them to a Marwi sliding QR mount and adapt two handle bar mounts for rear mounting to each bike.



    Bodies EL34's Marwi bullet (twin set). LED/driver an MR16 Red K2 Luxeon and 12 volt AC/DC driver integrated in base, from DX Modded MR16 unit to fit in MR11 housing, and kept reflector. I splay them out slightly now. Powered by either a 12 volt NiMH or more usually an 11.1 V 3S2P Lipo pack. A 14.8 would be close to max for the driver.



    At dusk, close to being out of beam too one side of them. Radbots below side firing Supreflashes each side below and forward of the DIY's for comparison.

    On the road (tipped down) to back them off some at night:



    Imperfections in my mod of the aluminum plate set one LED at a slight angle so narrowed its beam.

    A night video with leaning camera under street lights comparing different lights close at 1/8 mile and 1/4 mile under street lights. The DIYs are last. Xenon unknown output, Superflash about 12 lumens, Swerve 12 lumens, Radbot 1000 25 lumens each or 50 lumens for reference.



    In daylight visible at 1/4 mile with a lowering sun washing them out. Bright jacket/vests show at least as well, in those conditions. If you need a lot more, go Leopold's route. These get drivers to give 3 feet or more at night, I need to be brighter if I want them all over 3 feet in daylight, bu most grant me the space, whereas I rarely got them off the fogline before.

    Hope this helps.

  18. #18
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    Hello guys, I just wonder, have you tried to stand up behind these lights and look into them at night? These constructions are really "selfish" - will make the person following you completely blinded (and thus not seeing holes in street...). So please be kind and add some capability to dim the lights significantly if needed... Thanks
    I make my tail-lights dim-able, in case I need to ride in the middle of a pack. Since I typically have the brightest rear lights (300+ lumens) I usually volunteer to ride at the back of the pack and leave the lights on high.

    If you were being bothered by just a couple of superflashes (probably less than 30 lumens), you should have asked the rider to turn them on steady. I assume the blinking is what was bothering you. If the superflashes were on steady and affecting your ability to see road hazards that much, you need a much brighter front light.

    I've had people call my tail-lights "selfish" but I really don't see it that way. Unless the desire to survive is selfish . As long as I have to ride on narrow country 2 lanes with no shoulders, I want something that all the bubbas driving extra-wide pickups and SUVs will notice.

    Mark
    Nimium est melior!

  19. #19
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    rear lights is on my menu too.
    here is some of my rambling:
    most are happy with some blinky, for ease of getting it on and off, and not deal with cabling.
    Some folks commute, and in europe, a hard-wired light, front / rear with a generator is pretty standard. On that line, I think, I like a rear light wired to main battery, as not to forget to charge or change the rear batteries.
    So thinking, what looks darn nice, a truck or schoolbus LED marker.
    Maybe get the smallest one, that's it. little stumbling block, they are all 12V to 24V,..
    but that should do, no blink. I do have a 2" red marker, what's nice.
    by the time you get all the parts together , it gets more expensive.
    so for fixed lights, get the MS or niterider tail light.
    MTB, for mtb night rides, most don't have one, and really bright ones, are annoying for other riders.
    for mtb night riding , smaller is better, best, probably a little red bare bulb. since those usual rear lights, are not much visible from the side. A 360 little light, be probably good, for those riding in hunting season.
    other alternative, for MTB riding, just a little reflective tape, somewhere wrapped around.
    For the Road, don't forget all those little Reflectors the bike came with, they don't require a battery, and they do work. Seen some runners, with those reflective pieces on their shoes, works great. Even have a hunters orange vest with reflective tape.
    one more, got some 360 leds lenses, where I tried with those red tape, to fix turn-lights,
    unfortunately, it does look dim, and not very appealing , to put it mildly. So anything involved with that tape, is bound to be disappointing.
    Oh, those hard core commuters, also like all those cheesy lights, bolted down, so they don't have to take them off, and they don't get stolen.
    The opposite is true , for all those weight weenies, fashion mtb riders, they would not want to be seen, with a light on their bike at daytime at all. Thought, I did have some nice conversation with fellows, because I was too lazy to take them off, at daytime.
    Bonus is, when overcast, or really dense woods, it can give you a little light, if you turn it on.
    Like to see, more hard-wired tail-lights. cheers, Rob

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