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Thread: Specialised Bike Light Optics

  1. #1
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    Default Specialised Bike Light Optics

    For the last 2 years, I have been running a Luxeon III with a Taskled 700ma CC board, through a narrow beam fraen lens, supplied by a hub dynamo (6V 500mA) and 1N5821 bridge rectifier circuit w/smoothing cap. The system has been very reliable, but the light output to the road is, at best, adequate.
    I'm pretty much happy with the dynamo as the power supply, for various reasons of convenience, reliability etc, so I need to look at other ways to improve the perfomance for my application. My night time riding is all on paved roads, mostly in rural unlit areas, passing through some towns.
    One idea I have is to not rectify the output, instead running each A.C halfwave through a seperate L.E.D, for basically zero unnecessary losses. Also these could be some more modern K2 L.E.Ds.
    The other area I have looked at is the optics. Although the beam is supposedly 10 degrees, there is a large amount of spill noticeable, and to get the spot in a useful, optimal place results in a large amount of light wasted, as the light pointing above this point is not concentrated enough, and is pointing too far away to be of any practical use.
    Commercially available lamps designed for road commuting use address this issue by producing a very tight beam of a certain nature. This has the lions share of the produced light directed forwards towards a point just below the horizon (i.e. down on to the road, in the distance), and tapering off in a downwards direction, i.e. toward the source on the road in front. Any light above this point is sharply attenuated as it serves no purpose and is better off used where it is, as is any side spill. In this way they make the best use of the limited light available.
    Commercially produced L.E.D units of this type are now slowly becoming available, but aside from the fact I'd rather build my own, there are other disadvantages:
    A They are somewhat pricey, although well designed.
    B They are not upgradeable, making them useful only for a short time until they are effectively obselete and underpowered.

    So, basically my question is: Does anyone know where optics like these can be found. The only ones I've ever seen were spot, oval or a wide, flat type of beam.
    Last edited by tspoon765; 02-01-2006 at 03:40 AM.

  2. #2
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    Default Re: Specialised Bike Light Optics

    try a reflector instead of the fraen, maybe an IMS 27 mm.
    Focuses the beam to a narrower spot than the optic.
    Or the original Minimag-Reflector if smaller diameter is needed.

    (beamshots in the "guide to mod a mag"-tread) ((not exact name, but very close, I hope))

    Also use another circuit, as most dynamos are restricted to give 500 mA max.
    For example this one: http://www.led-treiber.de/html/dynamo-treiber.html.
    Use number 2 or 3 on the site, german language, but the circuits speak for themselves, dont they?

    When the dynamo is not restricted, You could power more led also. I have a model where I disassembled the electronics. Powers 2 pcs. Lux 5 in Series at 900 mA at ~20 km/h.
    (just mesure voltage without load; if You receive 15 Volts up, the dyno supposedly will not be restricted)
    Last edited by yellow; 02-01-2006 at 04:24 AM.

  3. #3
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    Default Re: Specialised Bike Light Optics

    Hi tspoon. I do alot of night trail on mountain bike. After much experimenting with reflectors, I find the IMS 17mm to be the most suitable for biking. I build my own bike lights from a cateye bike light body. The configuration is a direct drive 3watt (TYOK), 17mm reflectors, 3 Nimh 2500mah batteries and ofcourse heatsink. the forward voltage of the TYOK led seems to be ideally match with 3 rechargables in series. It blasted a good constant brightness for 2hours.

    Regarding the beam from IMS 17mm reflector, it gives you an ideal balance of spot and spill. The setup could easily illuminate at a distance as well right in front of the front wheel. I have no problem going at moderate speed. With the wrong beam, even riding casually is a problem on a 5watter. Hope this info helps.
    Last edited by Luxson; 02-03-2006 at 03:50 PM.

  4. #4
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    Default Re: Specialised Bike Light Optics

    "Specialised Bike Light Optics"? And i thought it was the company specialized (http://www.specialized.com)

  5. #5

    Default Re: Specialised Bike Light Optics

    Quote Originally Posted by Luxson
    The configuration is a direct drive 3watt (TYOK), 17mm lens, 3 Nimh 2500mah batteries and ofcourse heatsink. the forward voltage of the TYOK led seems to be ideally match with 3 rechargables in series.
    Was a low value resistor used, or was it really directly wired to the AA batteries?

  6. #6
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    Default Re: Specialised Bike Light Optics

    No resistor for high efficiency. The Nimh in series produce 3.6volt which suits the TYOK forward voltage(3.51v to 3.75v) nicely. By the way, I obtained my reflectors and led from Photon fanatic in dealers corner.
    Last edited by Luxson; 02-03-2006 at 03:49 PM.

  7. #7
    Flashaholic MikeHunt79's Avatar
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    Default Re: Specialised Bike Light Optics

    I'm using multiple flashlights for biking... I find having a few with a narrowish beam (5-10 deg) combined with another flashlight for flood beam works well.

    Luxson: What cateye body are you using? Does it cope with riding in the rain ok? I've been after a 3xAA for the same reasons as you - driving a Lux 3.

  8. #8
    Flashaholic* Steve K's Avatar
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    Default Re: Specialised Bike Light Optics

    Quote Originally Posted by tspoon765
    So, basically my question is: Does anyone know where optics like these can be found. The only ones I've ever seen were spot, oval or a wide, flat type of beam.

    hi Tspoon,

    As you have noticed, circular beampatterns are not ideal for bikes! There has been some experimentation with using half of the optic/reflector of a good dynamo headlight. A fellow named Olaf Schultz has published some reports on these experiments. There have been a number of references to this work on the BikeCurrent list. BikeCurrent is dedicated to bike electronics, and is hosted on Topica:
    www.topica.com/lists/bikecurrent

    The basic idea is that a dynamo headlight is sliced vertically down the middle. Using one of these halves, the led is mounted where the bulb was located, and aimed towards the reflector. This works nicely since the led only radiates over half a sphere, instead of nearly a whole sphere like a bulb.

    There is a commercial light built using this principle. It's called the Inoled. It is sold in the US by Peter White. He's taken a number of beamshots comparing it to other dynamo lights, and it compares rather well.
    http://www.peterwhitecycles.com/inoled.asp

    If you were to build your own, I'd recommend using a 5W Luxeon. It's very well matched to dynamos, so that you only need to rectify the AC power and feed it into the led. This will result in the led operating at about 3.5W.

    regards,
    Steve K.

  9. #9
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    Default Re: Specialised Bike Light Optics

    Quote Originally Posted by MikeHunt79
    I'm using multiple flashlights for biking... I find having a few with a narrowish beam (5-10 deg) combined with another flashlight for flood beam works well.

    I used to do that but after getting hold of the right lens, I find using multiple flashlights is not necessary.

    Luxson: What cateye body are you using? Does it cope with riding in the rain ok? I've been after a 3xAA for the same reasons as you - driving a Lux 3.
    Cateye EL-300 and the old HL-330H. For the EL-300, there is 4 AA batteries slots. I simply solder one slot with a wire to bypass.
    As for the HL-330H which originally accomodate 2 x C cells, a ready made 3AA battery adaptor housing fit nicely into it. I haven't figure out how to post picture just yet. I will do so when I got it right.
    The weather integrity is as original, but I did drill some holes for ventillation. Nevertheless, It did survived heavy downpour.

  10. #10
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    Default Re: Specialised Bike Light Optics

    Until we get the next generation of LEDs, I've given up on finding a single LED that can do duty as a lone bike light. Instead I just use 2 to 3 lights - two on the handlebars and one on my helmet. I usually go for a QIII w/R123, SL Jr. LED and a PT EOS on my helmet. That setup provides adequate light for medium speed riding out to maybe 50ft and only the QIII needs a battery change on most rides.

  11. #11
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    Default Re: Specialised Bike Light Optics

    Quote Originally Posted by Mattman
    Until we get the next generation of LEDs, I've given up on finding a single LED that can do duty as a lone bike light. Instead I just use 2 to 3 lights - two on the handlebars and one on my helmet. I usually go for a QIII w/R123, SL Jr. LED and a PT EOS on my helmet. That setup provides adequate light for medium speed riding out to maybe 50ft and only the QIII needs a battery change on most rides.
    In fact, I was directed to CPF while hunting for bicycle light. I laugh at the crazy people and was amused by the existence of flashaholics in CPF. In no time, I find myself to be one From there on in a short period of time , I obtained lots of unnecessary lights but I am sure I am the majority here. Streamlight ( stream dowm and lightened my wallet), Sure Fire ( yeah right ! Wallet sure caught fire) head lights, EDC, throw, flood and whatever light including Fenix the cat, which now flooded my display cabinet. But I like it! Why am I still classified unenlightened? I should be SCORCHED! Ok enough of rant, back to topic:

    Yes, your setup was almost identical to mine previously. Longbow micra, QIII with extention and PT EOS on helmet. QIII on R123 last mostly 30mins. With extension and 1760 lasted 1hr. Run time still not desirable. Beam wise is still consider narrow though kind of evenly bright. Mounting torch on handlebar with most available holder is still a problem for my case. Most can't hold its position after rattling downhill. Trust me on the above mentioned setup. the only light you need together with it is your EOS for those super winding trail.

    For race or high speed ride, I'll will throw in Electrolumen's 2x3watt which also used 17mm reflector.
    Last edited by Luxson; 02-04-2006 at 04:05 AM.

  12. #12
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    Default Re: Specialised Bike Light Optics

    Another good site for dynamo circuits and homebuilt/adapted lights :

    http://www.pilom.com/BicycleElectron...lectronics.htm

    I'm converting a BuschMuller reflector for a 5W WX0S, just bought an M10 brass bolt as an adjustable length heatsink.

    See
    http://www.pilom.com/BicycleElectronics/LumoLed.htm

    LeoW

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    Default Re: Specialised Bike Light Optics

    I came to CPF doing research on bicycle lighting for my recumbent. Been using various configurations over the years centering on the first Luxeon LEDs and R bins in particular. A minimag 500mA current regulated R bin punching through a Fraen LP optic served it's purpose for several years.

    Presently, I have a Fenix L1P as a helmet light and it is good enough to be seen with. A MillerMods L1P that pushes the Luxeon R bin at 500mA is in the mail and I should get it next week. The modded L1P will have a larger and brighter hotspot with 75 to 90 minutes runtime on a NiMH 2500mAH single AA cell. I am going to add a reflective piece over the top of the light about half an inch, it will reflect light coming from the light towards my helmet to make me easier to see. Add a little reflective tape to enhance visibility.

    Built a frame mounted light back in Sept 2003 to get me through the winter. A 2D Mag using a 700 to 800mA voltage regulator to motive the R2H Luxeon. Coupled with the Mag reflector, it punched a beam out 100 meters. The down side was the very narrow beam although the spill was nice.

    Completed construction on a 170 lumen variable LuxeonV 8AA to 2D Mag mod March 2005. It worked well as the hotspot was 4 times larger than the LuxI. I still want a larger hotspot so I have an HA-III 2D Mag and 8AA to 2D battery adapter ordered. Andrew Wynn is working on a 400 lumen, four Luxeon K2 beast for Mags. It takes 90 seconds to mod a Mag of your choice (C or D) I think the four 20mm reflectors split between 400 lumens should make the perfect frame mounted bike light. It should be available in May for $120.

    A 60 lumen single AA Luxeon helmet light and 400 lumen frame light should complete my lighting needs. Since they are mods, I can upgrade the LEDs as they advance in efficiency in the coming years.
    Peak Pacific AAA UP brass (EDC) E01 (keys), Peaks, Arcs, Fenix, Q5 Aspheric HA-III Mag etc.

  14. #14
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    Default Re: Specialised Bike Light Optics

    Hello BentHeadTX,

    Have you ever looked at optics like these? They have some that project an oblong beam that may be useful for bike riding.

    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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    Default Re: Specialised Bike Light Optics

    Hey SilverFox,
    That Carclo 2 degree optic would make my retired BB500 R2H minimag a very interesting light! For most practical purposes, not very useful but it is a retired light after all.
    Since my "bike lights" can be detached as used as flashlights, I prefer not the change the optics in them. Those chrome "shades" they put on low riders seem to do the trick for a 400 lumen light. It should block and reflect down the upper portion of the beam so to not dazzle drivers. The extra reflection will be nice when going through very strange places at low speeds.
    The LuxeonV Mag would benefit from the 25x4 27mm optic though. Not sure were to get one of them though.
    Peak Pacific AAA UP brass (EDC) E01 (keys), Peaks, Arcs, Fenix, Q5 Aspheric HA-III Mag etc.

  16. #16
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    Default Re: Specialised Bike Light Optics

    I have used both rectifier and anti-parallel arrangements in Luxeon bike lights and have a few comments to offer based on my experience.

    While the anti-parallel arragement has no rectifier losses, it does operate the leds a higher peak current compared with two leds in parallel with a rectifier.
    The leds are less efficient at high current so you loose light. Overall, with the same number of leds, I would go for the rectified option.

    Also, at low speed, unless the leds are well matched, visible flicker is worse with anti-parallel leds than with two leds (series or parallel) with a rectifier.
    I know this sounds odd, but believe me, I have done it and this is true - and I leant the light to another guy who also found it too flickery in anti-parallel mode (the light was switchable).

    To get more power from a dynamo, use two 3W luxeons in series with a rectifier - or even four in series for riding fast as the SON hub dynamo can easily produce enough for 4 in series above 12mph.

    'Lossless' active rectifiers are possible. I made one from mosfets and it is pretty close to 100% efficent. Losses are only a few mV.
    However, you cannot use one of these if you use a reervoir capacitor.

    I agree with Steve K that the LuxeonV is an excellent electrical match to a dynamo.
    However, it is a poor optical match to any collimator I know of.

    Reflectors - I have an untested opinion that small anular reflectors of the flashlight type waste an awful lot of light.
    You get a great beam pattern, but it is dimmer.
    The effective alternative would be a rearward-fed or side-fed reflector.

    I believe the best possible bike light would use a side-fed reflector to aim the light into a proper 'bike' beam with little above the horizontal etc.
    [EDIT] - I just checked out the Inoled that Steve K pointed to and that is doing exactly the right thing IMO - and thay beam pattern looks pretty good.

    As we are largely stuck with circularly-symetrical optics, I have used these.

    I did a lot of testing with Fraen '6deg' collimators and found what you found, not enough central 'punch'.

    To brighten the centre I use a '6deg' and a '30mm' collimator together (actually two of each). The 30mm's bright spot is just the job for distant illumination.
    For twisty country lanes, the combined beam could be a little wider and I am thinking about trying a 4x25deg Carclo to boost the width.

    Hella make a collimator-based battery bike light with what appears to be a proper bike pattern with a horizontal cut-off. (Available in the UK from Halfords) - I played with it in a shop and it looked good, but didn't get to ride behind it.
    If I was feeling rich I would buy a couple of these and use them as the basis for a dynamo light.

    Hope this helps.

    I am interesed to know if the switching regulator you use makes the light brighter than just connecting the led directly to the dynamo through a rectifier.

    And does your reservoir capacitor/regulator arrangement cut low-speed flicker? If so, down to what spped and how big is the capacitor?

    Steve
    Last edited by Bandgap; 02-06-2006 at 07:34 AM.

  17. #17
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    Default Re: Specialised Bike Light Optics

    Firstly thanks for all the replies people (I've bookmarked a few of those links). I ordered one of the InoLED 2 watt lamps today so I'll see how that goes.

    (Bandgap) I think the CC regulator I used now is actually probably unnecessary for the dynamo, but I keep it around as I have wired the system up with a little switchbox, which on A/ dynamo feeds LED, B/ Charge 4 x AA battery in my two rear blinkys, or C/ run LED from those batteries with dynamo contributing. (Also has a DC jack I can charge my phone or battery pack for my DAP when on holiday). When I run on C the light goes ever so slightly brighter, telling me that my setup is not supplying 700mA so I'm not even getting 2.6 watts output when on the dynamo. (Actually I measured once at 28km/h I was getting 5.6v and 600ma input to the CC regulator). Maybe I should wire it so the CC regulator is only present when running from the battery. I'm not altogether sure that the reservior cap is really needed either. At walking pace the light is flickering, anything above this is smoothish, but I think thats the same for everybody.
    I actually tried to make a synchronous rectifier and it failed on me twice. I didn't know you can't use a cap with this method, so that's probably why. Anything else I should know about this method ? I would probably hesitate to go back there anyway. The shottky diodes may have more losses but they are reliable.
    Getting back to the InoLED lamp, on the website it mentions that the LED is replaceable but that it needs to go back to germany to do this. I'll be checking out whether its possible to disassemble when it turns up, bearing in mind the cost of the thing of course.
    Lastly, people keep mentioning different sizes of 'IMS' lenses. Sorry to be a total newb, but is IMS a company or do those letters mean something else. Does anyone have a link to some IMS reflectors for sale.

  18. #18
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    Default Re: Specialised Bike Light Optics

    IMS is a company that makes reflectors. You can find them here: http://www.cadresearch.com/
    You can also find the reflectors on sale at theledguy's shop here: http://theledguy.chainreactionweb.com/index.php
    They're in the mod shoppe under opticalware and reflectors.

  19. #19
    Flashaholic* Steve K's Avatar
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    Default Re: Specialised Bike Light Optics

    Quote Originally Posted by tspoon765
    (Bandgap) I think the CC regulator I used now is actually probably unnecessary for the dynamo, but I keep it around as I have wired the system up with a little switchbox, which on A/ dynamo feeds LED, B/ Charge 4 x AA battery in my two rear blinkys, or C/ run LED from those batteries with dynamo contributing. (Also has a DC jack I can charge my phone or battery pack for my DAP when on holiday).
    aahhh, one of my favorite subjects: charging batteries from the dynamo!

    I spent some time fiddling around with using the dynamo to charge 5 AA nicads, and then regulating the power from the batteries to drive an incandescent headlight. Worked quite well, except for the very cold winter months (nicads really aren't in the mood to charge when it's 10F outside).

    I've still got the schematic here somewhere if there is any interest.

    What sort of batteries are you using, and how do you regulate the charge level?


    Steve K.

  20. #20
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    Default Re: Specialised Bike Light Optics

    The batteries are nimh 2300mah, two in each blinky, wired in series for 4.8v. I charge them through a low drop out regulator set to 5.8v. Hopefully this won't overcharge them, as they don't really get much use only ever powering the blinkys. They're pretty much used as an alternative load for the dynamo. I have the Shimano NX30, which is well known for having more drag when switched off above 28 km/h. Even if not drawing much current it may be enough to lessen the drag of the dynamo (which admittedly it negligable anyhow).
    The regulator only really works when the batteries are near full charge. Below this it can't reach 5.8v as the voltage drop from the diodes sees it below that, with the 0.2 dropout voltage dropping it further. However when the battery voltage rises the current should drop, allowing the dynamo voltage to rise, allowing the regulator to work correctly. I have contemplated putting a 25v zener in to protect the regulator but have not got around to it yet..

  21. #21
    Flashaholic* Steve K's Avatar
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    Default Re: Specialised Bike Light Optics

    5.8v float charge seems high for 4 nimh AA's. I used to charge my nicads at 1.35v/cell, and nicads don't mind float or trickle charging. If I were you, I wouldn't change anything right now, but if the batteries don't last long, consider dropping the voltage.

    Using a charger like this can be tricky if you are using a series regulator. At a given speed, when the current decreases, the dynamo voltage increases. For my Schmidt, if I used a 98v zener to clamp the voltage, the dynamo still produced more than a few milliamps of current (at high speeds). If you want to clamp the dynamo voltage, it's best to do it at low voltages. If you clamp at 25v and the dynamo still produces 200mA, then the zener has to dissipate 5 watts instead of the 3 watts that would be dissipated at 6 or 7 volts.

    Steve K.

  22. #22
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    Default Re: Specialised Bike Light Optics

    Before I got my switching sussed out 'properly' I only had one switch and was running the LED through the regulator too - hence the highish voltage. Although on my DAP I can see the voltage across the batteries as they are charging and it is routinely up aroung 5.80 volts, within 2-3 hours of a 12 odd hour charge cycle starting, ending up around 5.87 ish most of the time. As my commuting ride is 90 minutes each way at the most generally I'm not too worried about overcharging. Usually one way of my commute is in darkness so for that 75-90 minutes the blinkies draw their 100mA happily.
    Might be a different story when I go on tour, although then I will be recharging DAP battery packs at a fairly steady rate.
    Good point about the zener voltage too. It hasn't really sustained any damage all the time that I've run it so far, so I'll probably leave that anyway. Its interesting to see what other people have come up with when designing their LED bike lights, particularly the Guy who runs his dynamo up over 10v most of the time anyhow and uses a voltage doubler at low speeds.

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