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  1. #1
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    Help with constructing a [B]Universal triple-LED headlight[/B] greatly appreciated...

    Hi,

    I've taken the plunge and bought some dynohubs, not knowing which were best I've bought a shimano HB-NX30 and a HB-NX32 - seemingly these are the budget end of the shimano range, are they any good ?

    Anyway, I'd like to make some LED headlights as per Pilom.com.

    I would like to make the Universal triple-LED headlight with perhaps a few minor alterations.

    1) Obviously I will need a bridge rectifier - where should I mount it, can it be inside the headlight ?

    2) Same goes for a switch, where should that be best mounted ?

    3) What are the capacitors inside the headlight for ?

    4) Can I run the Universal triple-LED headlight from the dynohub with just a rectifier and no voltage doubler or voltage/current control ?

    Also I am in the UK so I could do with some help with my shopping list.

    Partlist
    • Stainless steel sugar shaker (mesh shaker) - trying local shops, proving tricky to find....
    • Stainless steel mounting bracket - to be arranged
    • Aluminium sheet, 5mm thickness - local engineering company
    • Various bolts - got these !! (well, it's a start)
    • Fraen triple collimator with holder - Luxeonstar.com ?
    • Luxeon Star LEDs (3ea), may be 1W or 2/3W - dealextreme.com ?
    • Heat-conductive glue (I use an Arctic Silver product) - no idea
    • Heatsink compound - pc stuff should work ?
    • Speaker cable - can't be difficult to find
    • Rubber sleeve to fit cable - ditto
    • 1.0 mm acrylic glass (cut from cheap safety goggles) - aren't they polycarbonate ?
    • O-ring 50mm inside diameter, 2mm thickness - any ideas anyone ?
    • Electrolytic capacitors 1000uF 16V (2ea) - maplins ?


    Here's where I am most confused why 1W LEDs ? Isn't the total power more likely to be about 6W ?

    Supposing the LEDs have about 3.5V through each of them @ 500 mA that is still 1.75W ?

    Scott has suggested buying Cree XR-E LEDs from http://www.dealextreme.com/details.dx/sku.2394

    and optics and holder from http://www.luxeonstar.com/fraen-lens...ika1fqislq6a01

    I found this switch in a different thread http://www.batteryspace.com/index.as...OD&ProdID=2656 I tried to order it but they wanted $55 for postage

    Any advice very gratefully received, especially on sourcing parts in the uk.

    TIA.....


  2. #2
    Zoom zoom zoom zoom bonk znomit's Avatar
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    I would recommend the quad or triple MR11 LED from cutter. Around 40US$ for three Q4 XR-E leds and optics, makes mounting very very easy(already on a plate so you don't need the extra aluminium). Narrow optic for the road.

    MR11 size so you have room inside the tin for the capacitors etc.

    The capacitors... the one across the LEDs smooths the output and stops the light flickering. You certainly need this one. The others tune the circuit to help with more light at lower speed. The stuff at pilom.com isn't hard to put together and works exceedingly well. If you're not sure what you're doing stick to the recipe.
    I would make circuit 7.

  3. #3
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    Quote Originally Posted by znomit View Post
    I would recommend the quad or triple MR11 LED from cutter. Around 40US$ for three Q4 XR-E leds and optics, makes mounting very very easy(already on a plate so you don't need the extra aluminium)
    Who is cutter ?

    How big is a MR11 ?

    Quote Originally Posted by znomit View Post
    The capacitors... the one across the LEDs smooths the output and stops the light flickering. You certainly need this one. The others tune the circuit to help with more light at lower speed
    I meant the two capacitors inside the Triple Luxeon LED Bicycle Headlight ?

    As the headlight has two capacitors in it, can I just use this with a bridge rectifier (maybe inside the headlight), a switch and the hub ?


  4. #4
    Zoom zoom zoom zoom bonk znomit's Avatar
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    Quote Originally Posted by Unknown Cyclist View Post
    Who is cutter ?

    How big is a MR11 ?
    Cutter is a reseller for Cree, in australia. They ship all over.

    The MR11 is 36mm diameter.

    See threads in my sig for more details

    Last edited by znomit; 07-31-08 at 02:38 AM. Reason: more detail

  5. #5
    You need a new bike supcom's Avatar
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    You can use a bridge rectifier and feed the three LEDs in series from the rectifier output. You do not need to install a capacitor unless you want to do so. three LEDs will come up to full brightness with imperceptible flicker at pretty low speed. I use no capacitor with a three LED system and have no problems.

    You should be able to find a switch at an electronics store in your area. Or, the easy thing to do it not install the switch and wire the rectifier directly to the dynohub and run the lights all the time. The drag is so low that it's no problem and the LEDs are unlikely to ever burn out. The light from the LEDs will be so bright that it's quite visible in daylight and will add to your safety.

  6. #6
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    Quote Originally Posted by supcom View Post
    You can use a bridge rectifier and feed the three LEDs in series from the rectifier output. You do not need to install a capacitor unless you want to do so. three LEDs will come up to full brightness with imperceptible flicker at pretty low speed. I use no capacitor with a three LED system and have no problems
    36mm or 50mm ?

    Which LEDs are you using ? and which hub ?

    I'd like to order some LEDS so I can get started, but there is too much choice...

    Cheers.

  7. #7
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    Here's an easy way to make the Bridge Rectifier using a terminal strip with 5 terminals.

    This one is designed to be used with a bottle type dynamo using the frame as ground. Hub dynamos typically do not ground to the frame. Soldering one of the output wires to the center tab and ground the mount tab to the frame will allow the frame to become an AC ground connection. Moving the diode leads to the fifth unused tab shown above prevents AC grounding to the frame. Here is a photo of a bridge rectifier connected to a front reflector mount.

    Water proofing is not required due to the fact the diodes are sealed from the elements with epoxy coating protecting the silicone substrate within.
    The Cree XR-E LED starts producing light with very little current. I no longer bother with the voltage doubler and boost capacitors. Older generations of power LED's did need the voltage doubler and boost capacitors. I just run a bridge rectifier and 1000uF capacitor.
    You don't really need a water proof switch. A simple in-line lamp cord switch will work fine. http://www.rd.com/familyhandyman/content/19543/
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  8. #8
    You need a new bike supcom's Avatar
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    Quote Originally Posted by Unknown Cyclist View Post
    36mm or 50mm ?

    Which LEDs are you using ? and which hub ?

    I'd like to order some LEDS so I can get started, but there is too much choice...

    Cheers.
    I modified two CREE LED flashlights by removing the current driver boards and wiring the LEDs to a bridge rectifier that I installed in the barrel of one of the flashlights. I also constructed a taillight from a red CREE emitter and a fan-shaped beam lens all mounted inside a 1" copper pipe cap. Everything is connected to a Schmidt Dynohub.

    One of my flashlights is an Ultrafire C3 light with about a 20mm diameter reflector. This light is used for wide beam close in lighting. The other light has a 50mm diameter reflector oriented to put light far down the road.

    The taillight is insanely bright, but the fan shaped beam reduces the light shining in the eyes of cyclists drafting behind me. But, even in bright sun, the light can be seen from a long way back.

    The flashlights, LEDs, and lenses all were purchased from dealextreme.

  9. #9
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    I'm planning to try a rear light with this 80x10 degree optic, from ledsupply.

    It sits flat on the LED star (no holder), so I'm thinking I'll just mount the star and then optic on some Al plate with epoxy, and seal around it with silicone... Should be as simple as it could possibly be, if not especially pretty.

    I intend to do one or two white ones in front too. I commute well lit streets, I don't really need to see, I just want to be seen, so the 80x10 flare seems a good idea. Possibly one flare and either a medium spot or 20x5 oval up front would be smart.

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    Hi Everyone,

    Thanks for the advice so far.

    For various reasons I'm going to (broadly) stick with the "Pilom Triple Luxeon LED Bicycle Headlight", though I'd like to put the rectifier inside the light and perhaps case mount a switch to the headlight as well.

    In the 'how to' it says: Connect capacitors across the LED-chain (both in parallel).

    Looking at the picture I can't quite see how this is done.

    Are the capacitors across the DC output of the bridge rectifier ?

    Are these capacitors polarised or non-polarised ?

    TIA...

  11. #11
    Member jrafael's Avatar
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    Check http://www.bikeled.org/

    Lots of good info about DIY bike led lights
    Challenges make you discover things about yourself that you never really knew. They're what make the instrument stretch -what makes you go beyond the norm.

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  12. #12
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    Quote Originally Posted by Unknown Cyclist View Post
    Connect capacitors across the LED-chain (both in parallel)
    They are across the LEDs themselves. If you have your rectifier in the light unit, then that is the same thing as the DC output of the rectifier.

    If you have the rectifier separate from the light, while it's the same thing electrically to put them across the rectifier output, if you read his page he points out that this is risky. You can give yourself a nasty shock, and/or destroy your LEDS if they charge up when the LEDS are not connected. Better to have them directly connected across the LEDs so there's no real chance of disconnect.

    Someone who understands it better than me please correct, but that cap can be polarized (C1 in Martin's circuits), since the current is DC, but they have to be connected the right way around. Some people suggest C1 doesn't really make a lot of difference. It can certainly be left out, it just reduces flicker.

    I'm planning to start out with circuit 5 without a C1, since it seems that I can get a non-polarized cap for C2. I'll add a C1 if I find the flicker annoying.
    Last edited by sping; 08-01-08 at 06:51 AM.

  13. #13
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    I visited Maplin's but unfortunately they didn't have anything I wanted in stock.

    However...I did find this:

    http://www.maplin.co.uk/Search.aspx?...source=15&SD=Y (item A18HH)

    and these:

    http://www.maplin.co.uk/Search.aspx?...=N78AL&DOY=1m8

    http://www.maplin.co.uk/Search.aspx?...=LF08J&DOY=1m8

    I'm still not sure which are the best LEDs to order - if I buy the triple collimator from Luxeon, which LEDs will give the best results with it?

    Cheers...

  14. #14
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    Update !!

    I finally found some !!





    Do they look suitable ?


  15. #15
    Velocommuter Commando Sirrus Rider's Avatar
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    Quote Originally Posted by Unknown Cyclist View Post
    I finally found some !!





    Do they look suitable ?

    Well, if you study the original plans you'll see the one they are using is the one with a screen and although I haven't made a set myself. I imgine the rationale is to avoid having to cut the top to make a a lens retaining ring. I'm afraid you are going to have to find a way to cut the top off of one of those lids.
    Riding 19 Years of Specialized Sirrus Tradition.
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  16. #16
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    Quote Originally Posted by Sirrus Rider View Post
    I imgine the rationale is to avoid having to cut the top to make a a lens retaining ring. I'm afraid you are going to have to find a way to cut the top off of one of those lids.
    I tried to find one with a mesh insert, but they don't seem to exist.

    Not even the cookware shop had any, any idea what they are used for ?

    Hopefully the top will come off nicely with a junior hacksaw and a little patience.


  17. #17
    You need a new bike supcom's Avatar
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    The mesh top is for confectioner's sugar.

    Pricey, but here's one example: http://www.kaboodle.com/reviews/will...h-sugar-shaker

  18. #18
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    Unknown
    Google "Stainless Steel Powder Sugar shaker" or "Stainless steel Flour shaker" here is another $9 example http://www.cooking.com/products/shprodde.asp?SKU=117067 lots of options out there, good luck with the build, take lots of photos this is a project I have been considering so I am looking forward to see how it turns out for you.

  19. #19
    Zoom zoom zoom zoom bonk znomit's Avatar
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    I found suitable ones in Kmart and a large hardware store too.
    Might be labelled spice tins.

  20. #20
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    I'm in the UK...

    We don't have Kmart (that I know of)....


  21. #21
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    Quote Originally Posted by znomit View Post
    The capacitors... the one across the LEDs smooths the output and stops the light flickering. You certainly need this one. The others tune the circuit to help with more light at lower speed.
    Hi,

    I was asking about the capacitors in the 'universal triple headlight' I think they are both connected across the rectifier output ?

    TIA.

  22. #22
    Scott n4zou's Avatar
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    Quote Originally Posted by sping View Post

    I'm planning to start out with circuit 5 without a C1, since it seems that I can get a non-polarized cap for C2. I'll add a C1 if I find the flicker annoying.
    Cree XR-E and SSC P4 emitters don't need C2 producing a lot of light at very low speeds. Bottle and Bottom Bracket type dynamos don't need C1 but hub type dynamos do need C1, unless you want the headlight flashing at very low speed making you very visible. It will quit flashing at just a couple miles per hour. Here is the circuit I currently use.



    I can recharge my GPS or cell phone as I pedal along.
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  23. #23
    dabbler
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    Quote Originally Posted by n4zou View Post
    Cree XR-E and SSC P4 emitters don't need C2 producing a lot of light at very low speeds. Bottle and Bottom Bracket type dynamos don't need C1 but hub type dynamos do need C1, unless you want the headlight flashing at very low speed making you very visible.
    Interesting, thanks. Well, I bought a cap for C2 (in fact, a few values, since I will probably be varying the number of LEDs), so I may as well get the boost.

    While I'll use a hub, I am not worried about the flicker, since I'm making a "be seen" light. I'm doing front and rear, and at this stage I'm happy to avoid having to make more of a housing for the lights. I'm using a flare optic which I'll put in some Al U-channel, and no other housing...

    Incidentally, I was just in REI, and they had a few utility/commuter bikes with hub dynamos and generic incandescent bulbs!? Crazy in this day and age, but I suppose it saves $15 or something on the price of the bike.

  24. #24
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    I think I've got nearly everything.....








    The tri-lens is a 'Fraen Narrow Beam Tri-lens for Lambertian LEDs' and has a part number - FT3-HNB1-LL01-H

    However, in the PDF datasheet for this item they show 4 different variations all with differing LED holders.

    The holder I have appears to be for Luxeon I Star, Luxeon I, III or V Emitter and the LED holder part of the tri-lens doesn't fit my Cree LEDs.

    How far should the LEDs go into the Tri-lens ?

    Should I trim the holders down until the LED is inside the tri-lens ?

    Should I buy different LEDs or a different tri-lens ?

    Last edited by Unknown Cyclist; 08-11-08 at 01:58 PM.

  25. #25
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    Hi,

    When these were recommended I assumed that the Cree LEDs fitted straight to the tri-lens, apparently that is not the case - at least not with the tri-lens I've received from Luxeon.

    Here's what Luxeon say:

    To assure the correct focal position of the lens and the Luxeon LED, specific holders have been designed. They can be identified by the shape of the cutout on the bottom of the holder.


    For batwing luxeons measurement A = 26.2 mm
    For lambertian Luxeons Measurement A = 26.7 mm

    For batwing luxeons measurement B = 22 or 22.5 mm
    For lambertian Luxeons Measurement B = 22.7 or 23.3 mm

    Clearly measurement B is the important with a possible difference of up to 1.3 mm.

    How do I make sure my LEDs are in the correct focal position ?

    Any ideas anyone ?

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